Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/76—Photosensitive materials characterised by the base or auxiliary layers
  • G03C1/795—Photosensitive materials characterised by the base or auxiliary layers the base being of macromolecular substances
  • G03C1/7954—Polyesters
• • 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
  • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
  • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
  • B29C55/04—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique
  • B29C55/06—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique parallel with the direction of feed
• • 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
  • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
  • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
  • B29C55/10—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial
  • B29C55/12—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial biaxial
  • B29C55/14—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial biaxial successively
  • B29C55/143—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial biaxial successively firstly parallel to the direction of feed and then transversely thereto
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/36—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using a polymeric layer, which may be particulate and which is deformed or structurally changed with modification of its' properties, e.g. of its' optical hydrophobic-hydrophilic, solubility or permeability properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/40—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used characterised by the base backcoat, intermediate, or covering layers, e.g. for thermal transfer dye-donor or dye-receiver sheets; Heat, radiation filtering or absorbing means or layers; combined with other image registration layers or compositions; Special originals for reproduction by thermography
  • B41M5/41—Base layers supports or substrates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/502—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording characterised by structural details, e.g. multilayer materials
  • B41M5/508—Supports
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
  • C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2033/00—Use of polymers of unsaturated acids or derivatives thereof as moulding material
  • B29K2033/18—Polymers of nitriles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2067/00—Use of polyesters or derivatives thereof, as moulding material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/0005—Condition, form or state of moulded material or of the material to be shaped containing compounding ingredients
  • B29K2105/0032—Pigments, colouring agents or opacifiyng agents
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/0088—Blends of polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/04—Condition, form or state of moulded material or of the material to be shaped cellular or porous
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2711/00—Use of natural products or their composites, not provided for in groups B29K2601/00 - B29K2709/00, for preformed parts, e.g. for inserts
  • B29K2711/12—Paper, e.g. cardboard
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
  • B29K2995/0018—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds having particular optical properties, e.g. fluorescent or phosphorescent
  • B29K2995/0025—Opaque
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M2205/00—Printing methods or features related to printing methods; Location or type of the layers
  • B41M2205/02—Dye diffusion thermal transfer printing (D2T2)
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M2205/00—Printing methods or features related to printing methods; Location or type of the layers
  • B41M2205/12—Preparation of material for subsequent imaging, e.g. corona treatment, simultaneous coating, pre-treatments
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
  • C08J2367/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
  • C08K3/013—Fillers, pigments or reinforcing additives
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L25/00—Compositions of, homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Compositions of derivatives of such polymers
  • C08L25/02—Homopolymers or copolymers of hydrocarbons
  • C08L25/04—Homopolymers or copolymers of styrene
  • C08L25/08—Copolymers of styrene
  • C08L25/12—Copolymers of styrene with unsaturated nitriles
• • 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
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
  • Y10S430/165—Thermal imaging composition
• • 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
  • Y10T156/00—Adhesive bonding and miscellaneous chemical manufacture
  • Y10T156/10—Methods of surface bonding and/or assembly therefor
• • 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.]
  • Y10T428/24802—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
• • 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.]
  • Y10T428/24802—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
  • Y10T428/24893—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.] including particulate material
• • 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
  • Y10T428/249921—Web or sheet containing structurally defined element or component
  • Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]
• • 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
  • Y10T428/249921—Web or sheet containing structurally defined element or component
  • Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]
  • Y10T428/249978—Voids specified as micro
• • 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
  • Y10T428/249921—Web or sheet containing structurally defined element or component
  • Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]
  • Y10T428/249987—With nonvoid component of specified composition
  • Y10T428/249991—Synthetic resin or natural rubbers
  • Y10T428/249992—Linear or thermoplastic
• • 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
  • Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
  • Y10T428/254—Polymeric or resinous material
• • 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
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31786—Of polyester [e.g., alkyd, etc.]
• • 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
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  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31855—Of addition polymer from unsaturated monomers

Definitions

• the present invention concerns non-transparent microvoided axially stretched films, a production process therefor.
• U.S. Pat. No. 3,755,499 discloses a synthetic sheet for writing purposes which consists essentially of a linear polyester selected from the group consisting of polyethylene terephthalate, polyethylene isophthalate, and copolymers of ethylene terephthalate and ethylene isophthalate, and a high polymer having a higher glass transition point than that of said linear polyester at a mixing ration of from 7 to 35% by weight of the latter with respect to the polymer mixture, which high polymer is selected from the group consisting of a polymethylmethacrylate, a copolymer of acrylonitrile an styrene, a copolymer of acrylonitrile, butadiene and styrene, said synthetic sheet having a very finely coarsened surface due to said high polymer which is uniformly dispersed in said linear polyester to constitute the nuclei for the irregular surface thereof.
• thermoplastic resin to be mixed may or may not have compatibility with the linear polyester, provided that it can be substantially uniformly mixed with and dispersed in the linear polyester at the time of forming, that the formed film, regardless of whether it is transparent or not, may produce a uniform mat surface upon being stretched and the film thus obtained is heat-shrinkable, acceptable in its writing properties, and possesses adequate opacity and that in order to further improve stability in the film size at a high temperature, it may be heat-treated at a temperature above the stretching temperature of the linear polyester and below the melting point of both mixing thermoplastic resin and the linear polyester.
• EXAMPLE 2 exemplifies the mixing of a copolymer of acrylonitrile and styrene having a glass transition temperature of 100 to 105° C. with polyethylene terephthalate in concentrations of 7 and 35% by weight and the forming of 150 ⁇ m thick film samples by melt-extrusion through a T-die. These film sheets were then stretched simultaneously by a biaxial stretching machine at a stretch ratio twice as large as the original length of the film in the longitudinal as well as transverse directions thereof at 85° C. and also stretched simultaneously biaxially three times longitudinally and three times transversely at 85° C. The resulting films were reported to have the following properties:
• U.S. Pat. No. 4,174,883 discloses a rear projection screen which comprises a light scattering member composed of a melted mixture consisting essentially of a dispersion medium polymer and a dispersed phase polymer dispersed therein, said melted mixture being obtained by melting and then mixing said polymers, wherein the absolute value of the difference between the refractive index of the dispersion medium polymer and the maximum refractive index of the dispersed phase polymer is from 0.01 to 0.25, and wherein the dispersion medium polymer is a member selected from high density polyethylene, low density polyethylene, polypropylene, 6,6-nylon, polyethylene terephthalate and polystyrene and the dispersed phase polymer is at least one member selected from the group consisting of high density polyethylene, low density polyethylene, polypropylene, polyethylene terephthalate, 6-nylon, 6,6-nylon, 6,10-nylon, polymethyl methacrylate, polymethyl acrylate, polyvinyl chloride resins
• U.S. Pat. No. 4,128,689 discloses a process for preparing thermoplastic sheets or webs, which process comprises the steps of: (i) extruding a foamable thermoplastic polymer mixture through the die of a screw extruder to produce a foamed extrudate in sheet or web form, the foamable thermoplastic polymer mixture containing at least a first and a second thermoplastic polymer, the first thermoplastic polymer being substantially crystalline and having a higher melting point than, and being substantially immiscible with, the second thermoplastic polymer, and the temperature of extrusion being equal to or greater than the melting point of the first thermoplastic polymer; (ii) stretching the foamed extrudate from step (i) in the direction of extrusion as it leaves the die to rupture most of the cells of the foamed extrudate and to elongate the walls of the collapsed cells in the direction of stretch; (iii) compressing the stretched extrudate from step (ii) while it remains plastic; and (iv) cooling and foam
• thermoplastic polymer is preferably selected from high density polyethylene, polypropylene, polybutene-1, poly 4-methylpentene-1, polyethylene terephthalate, nylon 6, nylon 66 and nylon 11 and the second thermoplastic polymer is preferably a non-crystalline thermoplastic polymer preferably selected from cellulose acetate, cellulose propionate, cellulose acetate butyrate, ethyl cellulose, polystyrene, styrene-acrylonitrile copolymers, polycarbonates, styrene and methyl styrene copolymers and phenylene oxide polymers.
• U.S. Pat. No. 4,243,769 discloses a method for providing a grossly homogeneous, permanently miscible mixture of polymers which has properties not evident in a simple blend of the polymers and which does not separate spontaneously into the component polymers, which comprises uniformly mixing (a) a polymer component containing a nitrile functionality with (b) a polymer component containing hydroxyl or esterified hydroxyl functional groups condensable with nitrites, said polymer components (a) and (b) tending to spontaneously separate from a simple blend thereof, in the presence of from about 0.001 to 8 percent by weight of the mixture of polymers and acid of an acid compatibilizing agent and for a period sufficient to provide the aforesaid permanently miscible mixture of polymers which, at ambient temperature, is in the form of a solid.
• the nitrile group material is preferably selected from the group consisting of polyacrylonitrile, polymethacrylonitrile, methacrylonitrile-acrylonitrile-vinyl acetate terpolymer, styrene-acrylonitrile copolymer, acrylonitrile-acrylic ester copolymer, acrylonitrile-butadiene-styrene terpolymer, acrylonitrile-styrene-alpha methyl styrene terpolymer, nitrile rubber, polycaprolactam-acrylonitrile graft copolymer, polyethylene-acrylonitrile graft copolymer, polyethylene terephthalate-acrylonitrile graft copolymer, cyano-styrene-methylmethacrylate copolymer, acrylonitrile-methyl vinyl ether copolymer, methacrylonitrile-
• U.S. Pat. No. 4,342,846 discloses a blend comprising: (1) a polyester resin formed by reaction of a dicarboxylic acid and a diol, preferably poly(ethylene terephthalate); and (2) an impact resistant interpolymer comprising crosslinked (meth)acrylate, crosslinked styrene-acrylonitrile, and uncrosslinked styrene-acrylonitrile polymeric components.
• EP 0 436 178A2 discloses a polymeric shaped article characterized in that said article is comprised of a continuous oriented polymer matrix having dispersed therein microbeads of a cross-linked polymer which are at least partially bordered by void space, said microbeads being present in an amount of 5-50% by weight based on the weight of said oriented polymer, said void space occupying 2-60% by volume of said article.
• EP 0 436 178A2 further discloses that said cross-linked polymer preferably comprises polymerizable organic material which is a member selected from the group consisting of an alkenyl aromatic compound having the general formula Ar—C(—R) ⁇ CH 2 wherein Ar represents an aromatic hydrocarbon radical, or an aromatic halohydrocarbon radical of the benzene series and R is hydrogen or the methyl radical; acrylate-type monomers including monomers of the formula CH 2 ⁇ C(—R′)—C(—OR) ⁇ O wherein R is selected from the group consisting of hydrogen and an alkyl radical containing from about 1 to 12 carbon atoms and R′ is selected from the group consisting of hydrogen and methyl; copolymers of vinyl chloride and vinylidene chloride, acrylonitrile and vinyl chloride, vinyl bromide, vinyl esters having the formula CH 2 ⁇ CH—O—C(—R) ⁇ O wherein R is an alkyl radical containing from 2 to 18 carbon atoms; acrylic acid, methacrylic acid
• EP-A 0 654 503 (which corresponds to U.S. Pat. No. 5,457,018) discloses a shaped article prepared from a polymer blend of 50 to 97 wt. % of a linear polyester and 3 to 50 wt. % of a polymer containing styrene e.g. a graft polymer of acrylonitrile, butadiene and styrene (ABS), a styrene-acrylonitrile copolymer or a high impact polystyrene (HIPS), wherein the percentages relate to the sum of the polyester and the polymer containing styrene.
• ABS graft polymer of acrylonitrile, butadiene and styrene
• HIPS high impact polystyrene
• EP-A 0 654 503 further discloses that a preferred polyester contains at least 80 wt. % polyethylene terephthalate and may contain up to 20 wt. % polyethylene isophthalate and the support material according to the invention may contain further additives, for example pigments, in particular TiO 2 , BaSO 4 , CaCO 3 , optical whiteners or blue dyes, which further increase covering power and improve sharpness, in particular 0.5 to 10 wt. %, related to the total weight of the constituent used, preferably 2 to 10, preferably 3.5 to 6.5 wt. % of TiO 2 pigment, preferably of the anatase type, are added.
• pigments in particular TiO 2 , BaSO 4 , CaCO 3
• optical whiteners or blue dyes which further increase covering power and improve sharpness
• Example 3 discloses the blending of 15 wt % related to the whole weight of constituents used, of a copolymer prepared from 72 wt % of styrene and 28 wt % acrylonitrile with an M w of approximately 115,000 and M w /M n ⁇ 3 then drying at 75° C. followed by melting in a PET extruder, extrusion through a slot, longitudinal stretching, application of a subbing layer, transverse stretching and heat-setting for 1 minute at 160° C.
• JP 09-255806A discloses a void-containing polyester film suitable for use in recording paper containing a number of minute voids produced by mixing a polyester with a thermoplastic resin incompatible with the polyester and orienting the obtained polymer mixture in at least one direction with the thermoplastic resin incompatible with the polyester being present in the film in the form of particles having a major axis diameter of 1-50 ⁇ m, a thickness of ⁇ 10 ⁇ m and a major axis/thickness ratio of 2-100.
• JP 09-255806A further discloses that the thermoplastic resin incompatible with the polyester may be polyethylene, polypropylene, polymethyl pentene and such polyolefin type resins, ionomer resin EP rubber and such copolymer polyolefin resins, polystyrene, styrene-acrylonitrile copolymers, styrene-butadiene-acrylonitrile copolymers and such polystyrene type resins, polyacrylate resins, polycarbonate resins or polyacrylonitrile type resins.
• JP 09-255806A exemplifies opaque and translucent biaxially stretched poly(ethylene terephthalate) using polystyrene or poly(methylpentene) as the incompatible thermoplastic resin and pigmentation with titanium dioxide.
• JP 2004-196951A discloses a polyester film, which is a film consisting of 78 to 55 weight % of a polyester (1) with butylene terephthalate repeating units as main component and 22 to 45 weight W of acrylonitrile-styrene copolymer (2), having as distinctive feature that the acrylonitrile-styrene copolymer (2) is dispersed in particle shape inside the polyester (1), the average particle length in major axis direction of those dispersed particles is 3 to 50 ⁇ m, the average particle length in minor axis direction is less than 5 ⁇ m, the average aspect ratio is 2.0 or more, the film's tear strength in the direction orthogonal to the major axis direction of the dispersed particles (T( ⁇ )) and the tear strength in the major axis direction (T(s)) are in a relation of T ( ⁇ )/T (s)>1.0, and it has easy tear property in the direction orthogonal to the major axis direction of the dispersed particles.
• U.S. Pat. No. 6,703,193 discloses an image recording element comprising a microvoided layer comprising a continuous phase polyester matrix having dispersed therein crosslinked organic microbeads and non-crosslinked polymer particles that are immiscible with the polyester matrix of said microvoided layer.
• U.S. Pat. No. 6,703,193 further discloses that if only non-crosslinked polymer particles that are immiscible with the polyester matrix are used in the microvoided layer of a silver halide display media the raw material and manufacturing cost is low, as a compounding step is not required, but the image sharpness is very poor due to the relatively large voids that result.
• the voided layer may contain white pigments which are known to improve the photographic responses such as whiteness or sharpness such as titanium dioxide, barium sulfate, clay, calcium carbonate or silica; and that addenda may be added to the layers to change the color of the imaging element.
• white pigments which are known to improve the photographic responses such as whiteness or sharpness such as titanium dioxide, barium sulfate, clay, calcium carbonate or silica; and that addenda may be added to the layers to change the color of the imaging element.
• addenda may be added to the layers to change the color of the imaging element.
• U.S. Pat. No. 6,703,193 fails to disclose the influence of image-wise heating on the opaque microvoided films disclosed therein.
• the prior art non-transparent microvoided axially stretched film has suffered from insufficient opacity together with a lack of dimensional stability or sufficient dimensional stability and insufficient opacity. Moreover, for particular applications the whiteness of the non-transparent microvoided axially stretched film was insufficient.
• a film consisting essentially of a continuous phase linear polyester matrix having dispersed therein a non-crosslinked random SAN-polymer and dispersed or dissolved therein at least one ingredient from the group of ingredients consisting of inorganic opacifying pigments, whitening agents, colorants, UV-absorbers, light stabilizers, antioxidants and flame retardants, wherein the film is white, microvoided, non-transparent and axially stretched; the linear polyester matrix has monomer units consisting essentially of at least one aromatic dicarboxylate, at least one aliphatic dimethylene and optionally at least one aliphatic dicarboxylate; and the weight ratio of the linear polyester to the non-crosslinked SAN-polymer is in the range of 2.0:1 to 19.0:1, wherein one of said at least one aromatic dicarboxylate monomer units is isophthalate and said isophthalate is present in said polyester matrix in a concentration of 15 mole % or less of all the dicar
• an image recording element comprising the above-described non-transparent microvoided axially stretched film, wherein the image is a non-photographic image.
• aspects of the present invention are also realized by a process for preparing a non-transparent microvoided axially stretched film comprising the steps of: i) mixing at least one linear polyester having monomer components selected from the group consisting of at least one aromatic dicarboxylic acid, at least one aliphatic diol and optionally at least one aliphatic dicarboxylic acid, a non-crosslinked random SAN-polymer and at least one ingredient from the group of ingredients consisting of inorganic opacifying pigments, whitening agents, colorants, UV-absorbers, light stabilizers, antioxidants and flame retardants in a kneader or an extruder to produce a mixture comprising the non-crosslinked random SAN-polymer in a polyester matrix, ii) forming the mixture produced in step i) in a thick film followed by quenching; and iii) stretching said thick film at a stretching tension of >2.5 N/mm 2 at a temperature between the glass transition temperature of said
• aspects of the present invention are also realized by a process for obtaining a transparent pattern comprising the step of: image-wise application of heat optionally supplemented by the application of pressure to the above-described non-transparent microvoided axially stretched film.
• voids or microvoids means microcells, minute closed cells, cavities, bubbles or pores or cellulation, which, for example, can be formed in an oriented polymeric film during stretching as the result of a void-initiating particle initiated by particles that are immiscible with the polyester matrix.
• the voids or microvoids can be unfilled or filled with air or a vapour of some sort. Even if initially unfilled the voids or microvoids may over time become filled with air or a vapour of some sort.
• opaque means a percentage opacity to visible light of greater than 90% as determined according to ASTM D589-97 or according to opacity test T425m-60 as published by TAPPI, 360 Lexington Avenue, N.Y., USA.
• foam as used in disclosing the present invention, means a substance that is formed by trapping many gas bubbles in a liquid or solid.
• film is an extruded sheet of a particular composition or a sheet consisting of a multiplicity of films with the same or different compositions produced by co-extrusion of liquids with the same or different compositions in contact with one another.
• film is also applied to axially and biaxially stretched films.
• film and foil are used interchangeably in the present disclosure.
• non-photographic image means a image which is not produced with a conventional silver halide gelatinous emulsion.
• dicarboxylate monomer unit in a linear polyester means a monomer unit derived either from a dicarboxylic acid or an ester thereof.
• dimethylene aliphatic monomer unit in a linear polyester means a monomer unit derived from a dimethylene aliphatic diol or an ether thereof, wherein the term aliphatic includes alicylic.
• linear polyester as used in disclosing the present invention, means a polyester comprising hydrocarbon dimethylene and dicarboxylate monomer units.
• linear aromatic polyester as used in disclosing the present invention, means a polyester comprising aliphatic dimethylene and aromatic dicarboxylate monomer units.
• inorganic opacifying pigment means a pigment capable of opacifying (i.e. rendering more opaque) which includes substantially white inorganic pigments having a refractive index of at least 1.4 and pigments, which as a dispersion in a polymer are capable upon stretching of causing opacity due to microvoiding.
• whitening agent means a white/colourless organic compound which exhibits a blue luminescence under the influence of ambient UV-light.
• support means a “self-supporting material” so as to distinguish it from a “layer” which may be coated as a solution or dispersion, evaporated or sputtered on a support, but which itself is not self-supporting. It also includes an optional conductive surface layer and any treatment necessary for, or layer applied to aid, adhesion.
• overprintable means capable of being overprinted by conventional impact and/or non-impact printing processes.
• conventional printing processes includes but is not restricted to ink-jet printing, intaglio printing, screen printing, flexographic printing, offset printing, stamp printing, gravure printing, dye transfer printing, thermal sublimation printing and thermal and laser-induced processes.
• pattern means a non-continuous layer which can be in any form of lines, squares, circles or any random configuration.
• layer means a (continuous) coating covering the whole area of the entity referred to e.g. a support.
• non-transparent film means a film capable of providing sufficient contrast to a transparent image to make the image clearly perceptible.
• a non-transparent film can be an “opaque film”, but need not necessarily be completely opaque in that there is no residual translucence i.e. no light penetration through the film.
• Optical density in transmission as measured with a MacBeth TR924 densitometer through a visible filter can provide a measure of the non-transparency of a film.
• ISO 2471 concerns the opacity of paper backing and is applicable when that property of a paper is involved that governs the extent to which one sheet visually obscures printed matter on underlying sheets of similar paper and defines opacity as “the ratio, expressed as a percentage, of the luminous reflectance factor of a single sheet of the paper with a black backing to the intrinsic luminous reflectance factor of the same sample with a white reflecting backing.
• 80 g/m 2 copy paper for example, is white, non-transparent and has an optical density of 0.5 as measured with a MacBeth TR924 densitometer through a yellow filter according to ISO 5-2 and metallized films typically have an optical density ranging from 2.0 to 3.0.
• transparent means having the property of transmitting at least 50% of the incident visible light without diffusing it and preferably at least 70% of the incident visible light without diffusing it.
• flexible means capable of following the curvature of a curved object such as a drum e.g. without being damaged.
• colorant means dyes and pigments.
• die as used in disclosing the present invention, means a colorant having a solubility of 10 mg/L or more in the medium in which it is applied and under the ambient conditions pertaining.
• pigment is defined in DIN 55943, herein incorporated by reference, as an inorganic or organic, chromatic or achromatic colouring agent that is practically insoluble in the dispersion medium under the pertaining ambient conditions, hence having a solubility of less than 10 mg/L therein.
• a film consisting essentially of a continuous phase linear polyester matrix having dispersed therein a non-crosslinked random SAN-polymer and dispersed or dissolved therein at least one ingredient from the group of ingredients consisting of inorganic opacifying pigments, whitening agents, colorants, UV-absorbers, light stabilizers, antioxidants and flame retardants, wherein the film is microvoided, non-transparent and axially stretched;
• the linear polyester matrix has monomer units consisting essentially of at least one aromatic dicarboxylate, at least one aliphatic dimethylene and optionally at least one aliphatic dicarboxylate; and the weight ratio of the linear polyester to the non-crosslinked SAN-polymer is in the range of 2.0:1 to 19.0:1, wherein one of said at least one aromatic dicarboxylate monomer units is isophthalate and said isophthalate is present in said polyester matrix in a concentration of 15 mole % or less of all the dicarboxy
• the non-transparent film is a white film.
• the non-transparent film is a coloured film.
• At least one aliphatic dicarboxylate is present in the polyester matrix in a concentration of less than 20 mole % of all dicarboxylate units in the linear polyester matrix.
• the film is a biaxially stretched film.
• the weight ratio of the linear polyester to the non-crosslinked SAN-polymer is in the range of 2.3:1 to 13:1, with a range of 2.5:1 to 10:1 being preferred and a range of 2.7:1 to 9.0:1 being particularly preferred.
• the weight ratio of the linear polyester to the non-crosslinked SAN-polymer is in the range of 2.85:1 to 7.0:1, with a range of 3.0:1 to 5.5:1 being preferred and a range of 3.2:1 to 4.9:1 being particularly preferred.
• the non-transparent microvoided axially stretched self-supporting film is provided with at least one of alphanumeric characters, an embossed pattern, an optionally embossed hologram and a continuous, half-tone or digital image.
• the film is provided on at least one side with a transparent overprintable layer i.e. suitable for impact or non-impact printing.
• This transparent overprintable layer can be provided over at least one of alphanumeric characters, an embossed pattern, an optionally embossed hologram and a continuous, half-tone or digital image on a surface of the non-transparent microvoided axially stretched self-supporting film.
• the film is provided on at least one side with a transparentizable porous overprintable layer i.e. suitable for impact or non-impact printing e.g. ink-jet printing.
• a transparentizable porous overprintable layer i.e. suitable for impact or non-impact printing e.g. ink-jet printing.
• Transparentizable porous layers transparentized by the application of a liquid with an appropriate refractive index, which can also be applied image-wise, are as disclosed in EP-A 1 362 710 and EP-A 1 398 175.
• This transparentizable overprintable layer can be provided over at least one of alphanumeric characters, an embossed pattern, an optionally embossed hologram and a continuous, half-tone or digital image on a surface of the non-transparent microvoided axially stretched self-supporting film with a transparent pattern.
• Transparentization of part of the transparentizable porous receiving layer can itself produce an image or the non-transparentized area of the opaque porous receiving layer can itself represent an image.
• the transparent pattern can, for example, be part of a banknote, a share certificate, a ticket, a credit card, an identity document or a label for luggage and packages.
• the non-transparent microvoided axially stretched self-supporting film has a thickness in the range from about 15 ⁇ m to about 500 ⁇ m, with from about 25 ⁇ m to about 300 ⁇ m being preferred, from about 50 ⁇ m to about 200 ⁇ m being particularly preferred and from about 75 to about 150 ⁇ m being especially preferred.
• the non-transparent microvoided axially stretched self-supporting film is provided with a subbing layer.
• the film is exclusive of foam.
• the film is exclusive of foaming agent and/or decomposition products of a foaming agent.
• the non-transparent microvoided axially stretched self-supporting film further contains an electroconductivity enhancing additive e.g. a metallic salt which ionizes in the melt giving enhanced electroconductivity such as magnesium acetate, manganese salts and cobalt sulphate. Suitable salt concentrations are about 3.5 ⁇ 10 ⁇ 4 moles/mole polyester.
• Enhanced polyester melt viscosity enables improved pinning of the melt on the chilling roller maintained at a temperature of 5 to 25° C. (preferably 15 to 30° C.) to cool the extrudate thereby enabling higher stretching forces to be realized and hence enhanced void-forming and a higher degree of opacification.
• aspects of the present invention are also realized by a process for preparing a non-transparent microvoided axially stretched film comprising the steps of: i) mixing at least one linear polyester having monomer components selected from the group consisting of at least one aromatic dicarboxylic acid and at least one aliphatic diol, a non-crosslinked random SAN-polymer and at least one ingredient from the group of ingredients consisting of inorganic opacifying pigments, whitening agents, colorants, UV-absorbers, light stabilizers, antioxidants and flame retardants in a kneader or an extruder to produce a mixture comprising the non-crosslinked random SAN-polymer in a polyester matrix, ii) forming the mixture produced in step i) in a thick film followed by quenching e.g.
• the quenched extruded film has a thickness of approximately 10 ⁇ m to approximately 6000 ⁇ m, with a thickness of approximately 100 to approximately 5000 ⁇ m being preferred, a thickness of approximately 200 ⁇ m to approximately 3000 ⁇ m being particularly preferred and a thickness of approximately 500 ⁇ m to approximately 2000 ⁇ m being especially preferred.
• the non-transparent microvoided axially-stretched film is produced by orienting the thick film by stretching e.g. in the machine direction or in a direction perpendicular to the machine direction (the transversal direction).
• Longitudinal orientation in the direction of extrusion can be carried out with the aid of two rolls running at different speeds corresponding to the desired stretching ratio by setting the surface speed V2 of the rotating rollers relative to the linear extrusion speed V1 so that the stretch ratio is V2/V1.
• the longitudinal stretching ratio should be sufficient to create voids.
• the longitudinal stretching operations known in the art to produce axially and biaxially oriented polyester film may be used.
• the combined film layers are passed between a pair of infra red heaters which heats the layers to a temperature above the glass transition temperature of the polyester (about 80° C. for polyethylene terephthalate) in the region where the stretching occurs.
• the stretching temperatures should be close to the glass transition temperature of the continuous phase polymer in order to improve opacity.
• the stretching temperatures should be below the glass transition temperature of the PETSAN-polymer.
• the longitudinal stretching is generally carried out at from about 80 to about 130° C.
• longitudinal stretching opacity is realized as a result of the voids produced in the film extending longitudinally from each particle of dispersed polymer.
• Transverse stretching is carried out at an angle substantially 90° to the direction of longitudinal stretching, with the angle being typically between about 70° and 90°.
• the angle being typically between about 70° and 90°.
• For transverse orientation use is generally made of an appropriate tenter frame, clamping both edges of the film and then drawing toward the two sides by heating the combined layers with the primer layer(s) thereon by, for example, passing through hot air heaters which heat the film above the glass transition temperature.
• the transverse stretching is carried out at from about 80 to about 170° C., preferably from about 90 to about 150° C.
• the transverse stretching of the film causes the voids to extend transversely.
• the stretching of the thick film is performed at a stretching tension >2.5 N/mm 2 , with a stretching tension >5.0 N/mm 2 being preferred and a stretching tension >7.0 N/mm 2 being particularly preferred.
• the stretching tension increases with decreasing stretching temperature.
• the film is biaxially stretched.
• the process comprises a further step, step (iv), in which the film is subjected to a further stretching process at an angle substantially 90° to the first stretching process to at least twice the initial length at a stretching tension of >2.5 N/mm 2 , with a stretching tension of >4.0 N/mm 2 being preferred.
• the process comprises a further step, step (iv), in which the film is subjected to a further stretching process at an angle substantially 90° to the first stretching process to at least twice the initial length at a stretching tension of >2.5 and step iv) is performed at a temperature at or below 30° C. above the glass transition temperature of the linear polyester matrix, with a temperature at or below 20° C. above the glass transition temperature of the linear polyester matrix being preferred and a temperature at or below 10° C. above the glass transition temperature of the linear polyester matrix being particularly preferred.
• the realizable stretching tension increases with decreasing stretching temperature.
• steps iii) and iv) are performed simultaneously e.g. with an apparatus produced by Brückner.
• the process further comprises, as a fifth step, a thermal fixation step.
• the stretching ratio for longitudinal stretching is between about 2 and about 6, with between about 2.5 and about 5 being preferred and between 3 and 4 being particularly preferred.
• the transverse stretching ratio is in the range of from about 2 to about 6, with a range of 2.5 to about 5 being preferred and a range of from about 3 to about 4 being particularly preferred.
• the higher the stretching ratio the higher is the opacity.
• the higher in %/min the stretching rate the higher the opacity.
• the linear polyester does not have butylene terephthalate as the main component.
• the axially or biaxially stretched film is finally passed through a second set of hot air heaters which blow hot air at a temperature of between 160 and 240° C. onto the film layers to heat-set or thermofix the film layers.
• the heat-set temperature must be sufficient to obtain crystallization of the polyester but care must be taken not to overheat the layers since the voids can collapse.
• increasing the heat-set temperature improves the dimensional stability of the film.
• An appropriate mix of properties can be obtained by varying the heat-set temperature.
• the preferred heat-set or thermofixation temperature in the case of polyethylene terephthalate or polyethylene naphthalate is at least 140° C. and preferably at least 150° and particularly preferably at least 175° C.
• a first subbing layer Before or after longitudinal stretching a first subbing layer, called a primer layer, may be applied to the non-voided polyester layer by a coating means such as an air knife coating system.
• the first subbing layer is for example formed from a (meth)acrylate copolymer, a poly(meth)acrylate, a polyurethane, a sulphonated polyester or a chloride containing copolymer such as vinylidene chloride copolymer in latex form having some hydrophilic functionality through the presence of a copolymerized unsaturated carboxylic acid which is applied as an aqueous dispersion.
• the optical density of the film measured in transmission with a visible filter due to microvoids is obtained by measuring the optical density of the film without void-producing ingredients as a function of film thickness to provide comparative values.
• the optical density of a film measured in transmission with a visible filter due to voids is then obtained by biaxially stretching a composition to which has been added the void-inducing ingredient and subtracting the measured optical density measured in transmission with a visible filter from the optical density measured in transmission with a visible filter for the film composition without void-inducing ingredient for the film thickness expected on the basis of the longitudinal and transverse drawing ratios.
• the linear polyester comprises at least one aromatic polyester resin e.g. poly(ethylene terephthalate) or a copolymer thereof.
• aromatic polyester resin e.g. poly(ethylene terephthalate) or a copolymer thereof.
• the different linear polyester resins present will undergo metathesis, condensing and decondensing so as to evolve upon sufficiently long heating into a single resin.
• the linear polyester comprises isophthalate monomer units in a concentration in respect of the total concentration of dicarboxylate monomer units of at least 1 mole %, with at least 3 mole % being preferred and at least 5 mole % being particularly preferred.
• the linear polyester comprises isophthalate monomer units in a concentration in respect of the total concentration of dicarboxylate monomer units of 12 mole % or less.
• the linear polyester is a copolymer of polyethylene terephthalate.
• the linear polyester comprises polyethylene terephthalate and a copolymer of ethylene terephthalate and ethylene isophthalate.
• Suitable polyesters include those produced from aromatic, aliphatic, or cyclo-aliphatic dicarboxylic acids or their esters, the dicarboxylate group having 4-20 carbon atoms, and aliphatic (including alicyclic) glycols or ethers thereof, the aliphatic dimethylene groups having 2-24 carbon atoms, and mixtures thereof.
• suitable aromatic dicarboxylates include terephthalate, isophthalate, phthalate, naphthalene dicarboxylates and sodiosulfoisophthalate.
• Suitable aliphatic dicarboxylates include succinate, glutarate, adipate, azelaiate (from azelaic acid), sebacate, fumarate, maleate (from maleic acid) and itaconate.
• suitable alicylic dicarboxylate are 1,4-cyclohexane-dicarboxylate, 1,3-cyclohexane-dicarboxylate and 1,3-cyclopentane-dicarboxylate.
• Suitable aliphatic dimethylenes include ethylene, propylene, methylpropylene, tetramethylene, pentamethylene, hexamethylene, neopentylene [—CH 2 C(CH 3 ) 2 —CH 2 ], 1,4-cyclohexane-dimethylene, 1,3-cyclohexane-dimethylene, 1,3-cyclopentane-dimethylene, norbornane-dimethylene, —CH 2 CH 2 (OCH 2 CH 2 ) n —, where n is an integer with 1 to 5 being preferred, and mixtures thereof.
• polyesters are well known in the art and may be produced by well-known techniques, for example, those described in U.S. Pat. No. 2,465,319 and U.S. Pat. No. 2,901,466.
• the linear polyester is a polymer having aromatic dicarboxylic acids selected from the group consisting of terephthalic acid, isophthalic acid and naphthalene dicarboxylic acid.
• the linear polyester is a polymer having aliphatic diols selected from the group consisting of ethylene glycol, 1,4-butanediol, neopentyl glycol, 2-endo, 3-endo norbornane dimethanol and 1,4-cyclohexanedimethanol, with a combination of ethylene glycol and 1,4-cyclohexanedimethanol being preferred.
• the linear polyester comprises polyethylene terephthalate and a copolymer of ethylene terephthalate and 1,4-cyclohexylene dimethylene terephthalate.
• At least 1 mole % of the aliphatic dimethylene monomer units in the linear polyester are neopentylene or 1,4-cyclohexanedimethylene monomer units, with at least 3 mole % being preferred and at least 5 mole % being particularly preferred.
• the number average molecular weight of the linear polyester is 10,000 to 30,000.
• poly(ethylene terephthalate modified by small amounts of other monomers is especially preferred.
• suitable polyesters include liquid crystal copolyesters formed by the inclusion of a suitable amount of a co-acid component such as stilbene dicarboxylic acid. Examples of such liquid crystal copolyesters are those disclosed in U.S. Pat. No. 4,420,607, U.S. Pat. No. 4,459,402 and U.S. Pat. No. 4,468,510.
• the linear polyester has a glass transition temperature from 40 to 150° C., preferably from 50 to 120° C. and particularly preferably from 60 to 100° C.
• the linear polyester is orientable.
• the linear polyester has an inherent viscosity determined in a 0.5 g/dL solution of 60 wt % phenol and 40 wt % ortho-dichlorobenzene at 25° C. of at least 0.45 dl/g with an inherent viscosity of 0.48 to 0.9 dl/g being preferred and an inherent viscosity of 0.5 to 0.85 dl/g being particularly preferred and an inherent viscosity of 0.55 to 0.8 dl/g being especially preferred.
• the linear polyester does not have butylene terephthalate as the main component.
• polyesters undergo metathesis during mixing in the melt resulting in a copolymer being formed with the overall composition of the mixture.
• a suitable matrix include a blend comprising poly(ethylene terephthalate) and poly(1,4-cyclohexylene dimethylene terephthalate).
• the concentration of SAN-polymer is at least 5% by weight, with at least 10% by weight being preferred and at least 15% by weight being particularly preferred.
• the concentration of SAN-polymer is 35% by weight or less, with 30% or less being preferred and 25% by weight or less being particularly preferred.
• the concentration of AN-monomer units in the SAN-polymer is 15 to 35% by weight, with 18 to 32% by weight being preferred and 21 to 30% by weight being particularly preferred.
• the SAN polymer additive of the present composition is a known genus of polymer consisting essentially of a styrenic monomer component, including styrene as well as an alpha-lower alkyl-substituted styrene or mixtures thereof and an acrylonitrilic monomer component including acrylonitrile as well as an alpha-lower alkyl substituted acrylonitrile or mixtures thereof.
• lower-alkyl is meant a straight or branched chain alkyl group of 1 to 4 carbon atoms exemplified by the methyl, ethyl, isopropyl and t-butyl groups.
• the styrene component is generally styrene, alpha-straight chain alkyl substituted styrene, typically alpha-methyl-styrene, or mixtures thereof with styrene being preferred.
• the acrylonitrile component is generally acrylonitrile, alpha-methyl-acrylonitrile or mixtures thereof with acrylonitrile being preferred.
• the styrene component is present in a major weight proportion, i.e. in a weight proportion of greater than 50%, typically about 65% to about 90%, especially about 70% to about 80%, based on the combined weight of the styrene component and the acrylonitrile component.
• the acrylonitrile component is present in a minor proportion, i.e. in a weight proportion of less than 50%, typically about 10% to about 35% especially about 20% to 30% based on the combined weight of the styrene monomer component and the acrylonitrile monomer component.
• SAN polymer class is more particularly identified and described in R. E. Gallagher, U.S. Pat. No. 3,988,393, issued Oct. 26, 1976 (especially at Column 9, lines 14-16 and in claim 8), in “Whittington's Dictionary of Plastics”, Technomic Publishing Co., First Edition, 1968, page 231, under the section headed “Styrene-Acrylonitrile Copolymers (SAN)”, and R. B. Seymour, “Introduction to Polymer Chemistry”, McGraw-Hill, Inc., 1971, page 200, (last two lines) to page 201 (first line).
• the number average molecular weight of the non-crosslinked random SAN-polymer is 30,000 to 100,000, with 32,000 to 80,000 being preferred, 35,000 to 70,000 being particularly preferred and 40,000 to 60,000 being especially preferred.
• Typical SAN-polymers have number averaged molecular weights of 45,000 to 60,000 and polymer dispersities (M w /M n ) of 1.2 to 2.5.
• the weight average molecular weight of the non-crosslinked random SAN-polymer is in the range of 50,000 to 200,000, preferably in the range of 75,000 to 150,000.
• the dispersed SAN-polymer has a number averaged particle size of 1.5 ⁇ m. The smaller the particle size of the dispersed SAN-polymer, the higher the opacity.
• the concentration of inorganic opacifying pigment is ⁇ 0.1% by weight, with ⁇ 1% by weight being preferred.
• the inorganic opacifying pigment is present in a concentration of ⁇ 10% by weight, with ⁇ 3% by weight being preferred.
• the film comprises ⁇ 10% by weight of inorganic opacifying pigment each with a refractive index of less than 2.0, with ⁇ 3% by weight being preferred.
• the film comprises ⁇ 10% by weight of inorganic opacifying pigment each with a refractive index of at least 1.5.
• the film further comprises an inorganic opacifying pigment having a number averaged particle size between 0.1 and 10 ⁇ m, with 0.2 to 2 ⁇ m being preferred and 0.2 to 1 ⁇ m being particularly preferred.
• the film further comprises an inorganic opacifying pigment selected from the group consisting of silica, zinc oxide, zinc sulphide, lithopone, barium sulphate, calcium carbonate, titanium dioxide, aluminium phosphate and clays.
• the titanium dioxide may have an anatase or rutile morphology and may be stabilized by alumina oxide and/or silicon dioxide.
• the aluminium phosphate can be an amorphous hollow pigment e.g. the BiphorTM pigments from BUNGE.
• Addition of an inorganic opacifying pigment has the advantage of stabilizing the orientation of the polyester, so that the non-transparent microvoided axially stretched self-supporting film can be stabilized at temperatures of 175° C. without substantially affecting the opacity of the non-transparent microvoided axially stretched self-supporting film.
• an inorganic opacifying pigment such as BaSO 4 or TiO 2
• thermofixing of the polyester is possible, but only at the expense of some of the opacity of the non-transparent microvoided axially stretched self-supporting film.
• pigments with a refractive index below 2.0, such as BaSO 4 do not of themselves provide substantial opacity due to the small refractive index differences between the pigment and the polymer matrix.
• Titanium dioxide particles dispersed in polymer films have of themselves been found not to induce microvoiding upon stretched the films.
• the concentration of whitening agent is ⁇ 0.5% by weight, with ⁇ 0.1% by weight being preferred, ⁇ 0.05% by weight being particularly preferred, ⁇ 0.035% by weight being especially preferred.
• the film further comprises a whitening agent selected from the group consisting of bis-benzoxazoles e.g. bis-benzoxazolyl-stilbenes and bis-benzoxazolyl-thiophenes; benzotriazole-phenylcoumarins; naphthothiazole-phenylcoumarins; triazine-phenylcoumarins and bis(styryl)biphenyls.
• a whitening agent selected from the group consisting of bis-benzoxazoles e.g. bis-benzoxazolyl-stilbenes and bis-benzoxazolyl-thiophenes; benzotriazole-phenylcoumarins; naphthothiazole-phenylcoumarins; triazine-phenylcoumarins and bis(styryl)biphenyls.
• Suitable whitening agents are:
• UVITEX ® OB CIBA UVITEX ® OB-ONE CIBA Eastobrite OB 2,5-thiophenediylbis(5-tert- Eastman Chemical butyl-1,3-benzoxazole) bis-benzoxazolyl-stilbene bis-benzoxazolyl-thiophene
• the film further comprises a flame retardant.
• the film further comprises a flame retardant selected from the group consisting of: brominated compounds; organophosphorus compounds; melamine; melamine-derivatives, e.g. melamine salts with organic or inorganic acids such as boric acid, cyanuric acid, phosphoric acid or pyro/poly-phosphoric acid, and melamine homologues such as melam, melem and melon; metal hydroxides e.g. aluminium hydroxide and magnesium hydroxide; ammonium polyphosphates and zinc borate e.g. with a composition of xZnO.yB 2 O 3 .zH 2 O such as 2ZnO.3B 2 O 3 .3.5H 2 O.
• a flame retardant selected from the group consisting of: brominated compounds; organophosphorus compounds; melamine; melamine-derivatives, e.g. melamine salts with organic or inorganic acids such as boric acid, cyanuric acid, phosphoric
• Suitable flame retardants include:
• the film further comprises an antioxidant.
• the film further comprises an antioxidant selected for the group consisting of organotin derivatives, sterically hindered phenols, sterically hindered phenol derivatives and phosphites.
• Suitable flame retardants include:
• ETHANOX ® 310 Organotin catalyzed penta-erythritol Albemarle Corporation tetrakis (3-(3,5-di-t-butyl-4- hydroxyphenyl)-propionate)
• ETHANOX ® 314 1,3,5-tris(3,5-di-tert-butyl-4- Albemarle Corporation hydroxybenzyl)-1,3,5-tria-zine- 2,4,6(1h,3h,5h)-trione
• ETHANOX ® 330 1,3,5-trimethyl-2,4,6-tris (3,5-di- Albemarle Corporation tert-butyl-4-hydroxy-benzyl) benzene
• the film further comprises a light stabilizer.
• the film further comprises a hindered amine light stabilizer.
• Suitable light stabilizers include:
• the film further comprises a UV-absorber.
• the film further comprises an UV-absorber selected from the group consisting of benzotriazole derivatives and triazine derivatives.
• Suitable UV-absorbers include:
• an image recording element comprising the non-transparent microvoided axially stretched film, according to the present invention.
• the film is provided on at least one side with a transparent overprintable layer i.e. for impact and non-impact printing.
• the film is provided on at least one side with a non-transparent overprintable layer i.e. suitable for at least one impact and non-impact print technique.
• the film is provided on at least one side with a non-transparent transparentizable overprintable layer i.e. i.e. suitable for at least one impact and non-impact print technique.
• the film is provided on at least one side with an ink-jet receiving layer.
• Typical receiving layers are either porous in the case of aqueous or solvent inks or pastes to enable rapid drying to the touch or are non-porous in the case of phase-change inks or curable inks e.g. radiation curable inks.
• Porous receiving layers typically comprise at least one pigment such as silica or alumina; at least one binder, such as an ammonium salt of a styrene-acrylate-acrylic acid terpolymer; a surfactant e.g. an anionic surfactant such as an aliphatic sulphonate; optionally a levelling agent, such as polydimethylsiloxane, and optionally a mordant.
• the film is provided on at least one side with an imaging layer e.g. a photographic layer e.g. a silver halide emulsion layer; a photothermographic element and a substantially light-insensitive thermographic element; and the dye receiver layer of a dye thermal transfer system.
• an imaging layer e.g. a photographic layer e.g. a silver halide emulsion layer
• a photothermographic element and a substantially light-insensitive thermographic element e.g. a substantially light-insensitive thermographic element
• the dye receiver layer of a dye thermal transfer system e.g. a dye thermal transfer system.
• the film is provided on at least one side with a writable layer e.g. with a pencil, ball-point pen and fountain pen.
• a writable layer e.g. with a pencil, ball-point pen and fountain pen.
• a process for obtaining a transparent pattern comprising the step of: image-wise application of heat optionally supplemented by the application of pressure to a non-transparent microvoided axially stretched film consisting essentially of a continuous phase linear polyester matrix having dispersed therein a non-crosslinked random SAN-polymer and at least one ingredient from the group of ingredients consisting of inorganic opacifying pigments, whitening agents, colorants, UV-absorbers, light stabilizers, antioxidants and flame retardants, wherein the linear polyester has monomer components consisting essentially of at least one aromatic dicarboxylic acid, at least one aliphatic diol and optionally at least one aliphatic dicarboxylic acid, the weight ratio of the non-crosslinked SAN-polymer to the linear polyester is in the range 3.0 to 5.5 and wherein the concentration of AN-monomer units in the SAN-polymer is 18 to 35% by weight.
• the film is a biaxially stretched film.
• the concentration of inorganic opacifying pigment is ⁇ 0.1% by weight, preferably ⁇ 1% by weight.
• the concentration of whitening agent is ⁇ 0.05% by weight, with ⁇ 0.035% by weight being preferred.
• the heat is applied by a heated or hot stamp, a thermal head, a heated or hot bar or a laser.
• the heating can be carried out from one or both sides of the film.
• the proportionate transparentization realized upon obtaining a transparent pattern, according to the present invention increases with decreasing film thickness, with thicknesses of 100 ⁇ m or less being preferred. Optical density changes of at least 0.4 can be readily realized or up to 40% without significant changes in film thickness.
• the transparentization effect realized by the process for obtaining a transparent pattern, according to the present invention results from a combination of heat supplied by a heat source, the pressure between the heat source and the film and the time the heat source is applied.
• the heat has to be applied for at least 1 ms either continuously or non-continuously.
• Heating with a thermal head can be with a single heat pulse, but multiple short heating pulses are preferred to avoid overheating of the heating elements.
• a foil can be used between the thermal head and the non-transparent microvoided axially stretched self-supporting film during the heating process e.g. a 6 ⁇ m thick PET-film can be interposed between the non-transparent microvoided film and the thermal head to prevent possible contamination of the thermal head.
• Thermal head printers such as the DRYSTAR-printers supplied by AGFA-GEVAERT N.V., can be used produce the transparent pattern of the present invention e.g. as personalized watermarks.
• This transparentization effect is accompanied by a relief pattern, which can be detected by touch i.e. in a tactile manner, and by changes in glossiness.
• This relief pattern is more pronounced the higher the temperature of the heat source, this embossing effect increasing with temperature between 110° C. and the melting point of the linear polyester matrix.
• the tactile relief obtained by applying a hot stamp to a non-transparent microvoided axially stretched self-supporting film is much more pronounced than that obtained using a thermal head.
• the degree of transparency realized depends upon the stamp/thermal head printing conditions: time, temperature and pressure.
• the thermofixation history of the material is also important.
• the heated-induced transparentization of the non-transparent microvoided axially stretched self-supporting film can be carried out before or after the optional application of a layer, such as an ink-jet receiving layer and before or after transparentization.
• the relative positioning of the transparentized areas and transparency in the support can be of value as an additional security measure.
• the heat is applied non-continuously.
• a transparent overprintable layer is provided on the film prior to the image-wise application of heat.
• a transparent overprintable layer is provided on the film after the image-wise application of heat.
• Non-transparent microvoided axially stretched films can be used as synthetic paper for printing and other applications, as a support for non-photographic imaging materials e.g. impact and non-impact (e.g. electrophotography, electrography and ink jet) receiving materials, photothermographic recording materials, substantially light-insensitive thermographic recording materials, dye sublimation printing, thermal transfer printing, etc., in security and anti-counterfeiting applications e.g. in tickets, labels, tags, an ID-card, a bank card, a legal document, banknotes and packaging and can also be integrated into packaging.
• non-photographic imaging materials e.g. impact and non-impact (e.g. electrophotography, electrography and ink jet) receiving materials, photothermographic recording materials, substantially light-insensitive thermographic recording materials, dye sublimation printing, thermal transfer printing, etc.
• security and anti-counterfeiting applications e.g. in tickets, labels, tags, an ID-card, a bank card, a legal document, banknotes and packaging
• POLYESTER MFI 270° C./ Inherent PET- 1.20 kg viscosity** T g nr [cm 3 /10 min] [ ⁇ ] [dl/g] [° C.] 01 T03* polyethylene terephthalate 34.8 0.60 80.5 02 T04* polyethylene terephthalate 34.8 0.60 80.5 03 WP75# polyester of 98.5 mol % 0.77 80 terephthalate, 1.5 mol % isophthalate and 100 mol % ethylene units 04 DP9990# polyester of 90 mol % 0.60 terephthalate, 10 mol % isophthalate and 100 mol % ethylene units 05 DP9970# polyester of 70 mol % terephthalate, 30 mol % isophthalate and 100 mol % ethylene units 06 RADICRON polyester of 100 mol % 1480# terephthalate, 73 mol % ethylene and 27 mol % neopentylene units *AGFA-GEVAERT
• Extrudates 1 to 4 were produced by mixing the respective parts of PET 01, PET 03, of the particular SAN used, BaSO 4 and UVITEX OB-one given in Table 1, drying the resulting mixture at 150° C. for 4 hours under vacuum ( ⁇ 100 mbar), melting them in a PET-extruder and finally extruding them through a sheet die and cooling the resulting extrudates.
• Extrudates 1 to 4 were axially stretched longitudinally with an INSTRON apparatus in which the extrudates are heated in an oven mounted on the apparatus under the conditions given in Table 2 to yield the axially stretched films of EXAMPLES 1 to 23, EXAMPLES 24 to 35, EXAMPLES 36 to 46 and EXAMPLES 47 to 58 respectively.
• the stretching speed was not found to have a significant influence upon the optical density observed, although the results appear to show that it has a minor effect as does the stretching tension. Particularly high opacities appeared to be obtained for stretching tensions greater than 4 N/mm 2 .
• the PET-types and SAN-types used for producing the extrudate used in producing of the films of EXAMPLES 59 to 78 are given in Table 3.
• the PET, SAN, BaSO 4 and UVITEX OB-one in the weight percentages given in Table 3 were mixed and then dried at 150° C. for 4 hours under vacuum ( ⁇ 100 mbar), the mixtures then melted in a PET-extruder and extruded through a sheet die and cooled to produce the extrudates 1, 2 and 5 to 22.
• Tables 6 and 7 demonstrate the stability of the non-transparent microvoided axially stretched self-supporting films comprising ⁇ 3% by weight of inorganic opacifying pigment each with a refractive index of less than 2.0 subjected to the image-wise heating process of the present invention to provide a transparent pattern, according to the present invention.
• the film of INVENTION EXAMPLE 72 was mounted in an Instron 4411 apparatus and was heated at temperatures between 138 and 200° C. for 5 seconds with a soldering iron in the upper clamp making contact with the film at a pressure of 0.5 N/mm 2 .
• the optical densities of the film after the test were measured in transmission with a MacBeth TR924 densitometer with a visible filter. The results are summarized in Table 8 below.
• thermofixated stretched film was heated at a temperature of 175° C. for 5 seconds at different pressures between 0.1 N/mm 2 to 1.50 N/mm 2 in the Instron apparatus with the results shown in Table 9 below.
• thermofixated stretched film was heated at a temperature of 175° C. and a pressure of 0.5 N/mm 2 in the Instron apparatus for different times between 2 and 300 seconds with the results shown in Table 10 below.
• a 8 inch (203.2 mm) by 10 inch (254 mm) piece of the film of INVENTION EXAMPLE 65 (120 ⁇ m thick and with an optical density of 0.92) was fed into a standard DRYSTAR DS5500 printer from AGFA-GEVAERT N.V. with a Toshiba thermal head and a rectangular area printed at a line time of 4.3 ms with the maximum power of 49.5 mW.
• the printed area had an optical density of 0.80 as measured with a MacBeth TR924 densitometer with a visual filter.
• the low reduction in optical density is probably due to a too low pressure between the sheet and the thermal head due to the DS5500 printer being designed for film ca. 200 ⁇ m thick with a 175 ⁇ m thick support rather than the 100 ⁇ m thick film used in the experiment.
• Transparentization tests were carried out on the film of INVENTION EXAMPLE 77 as described in INVENTION EXAMPLE 79.
• the transparentization was determined at various temperatures between 120 and 190° C. at a contact pressure of 0.5 N/mm 2 and a contact time of 5 seconds as described for INVENTION EXAMPLE 79 with the results given in Table 12.
• the PET-types and SAN-types used for producing the extrudates used in producing of the films of EXAMPLES 83 to 87 and COMPARATIVE EXAMPLES 1 to 3 are given in Table 16.
• the PET, SAN, TiO 2 and UVITEX OB-one in the weight percentages given in Table 13 were mixed and then dried at 150° C. for 4 hours under vacuum ( ⁇ 100 mbar), the mixtures then melted in a PET-extruder and extruded through a sheet die and cooled to produce INVENTION EXTRUDATES 22 to 26 and COMPARATIVE EXTRUDATES1 to 3.
• optical densities of the films of INVENTION EXAMPLES 83 to 87 and the films of COMPARATIVE EXAMPLES 1 to 3 were measured in transmission with a MACBETH TR924 densitometer with a visible filter and the results given in Tables 14 and 15 for the films of INVENTION EXAMPLES 86 to 90 and those of COMPARATIVE EXAMPLES 1 to 3 respectively.
• the films of INVENTION EXAMPLES 84, 85 and 87 and COMPARATIVE EXAMPLES 1 to 3 were each mounted in an Instron 4411 apparatus and were heated at various temperatures between 120 and 190° C. for 5 seconds with a soldering iron in the upper clamp making contact with the film at a pressure of 0.5 N/mm 2 .
• the optical densities of the film after the tests were measured in transmission with a MacBeth TR924 densitometer with a visible filter and the film thicknesses were also measured. The results are summarized below in Tables 16 and 17 respectively.
• the 1083 ⁇ m thick extrudate of COMPARATIVE EXAMPLE 5 with a composition of 2% by weight of titanium dioxide, 100 ppm UVITEX OB-one and 98% by weight of PET02 was produced as described for EXAMPLES 1 to 58 and had an optical density measured with a MacBeth TR924 densitometer in transmission mode with a visible filter of 1.35.
• the extrudate was stretched in the length direction as described in EXAMPLES 1 to 58 under the conditions given in Table 20.
• This relationship provides the optical density attributable to a 2% by weight concentration of the titanium dioxide pigment used as a function of film thickness.
• the ca. 1100 ⁇ m thick extrudates of EXAMPLES 88 to 105 all with 2% by weight of titanium dioxide and 15% by weight of SAN 06 were produced by mixing the ingredients in Table 22 in the proportions given in Table 22 and then drying the mixture at 150° C. for 4 hours under vacuum ( ⁇ 100 mbar) before melting in a PET-extruder, extrusion through a sheet die and cooling to produce the extrudates of EXAMPLES 88 to 108 having a density of ca. 1.3 g/mL as summarized in Table 22 together with the isophthalate (IPA):terephthalate (TPA) ratio.
• IPA isophthalate
• TPA terephthalate
• Table 24 gives the measured thickness; the expected thickness i.e. thickness if no void-forming based on the extrudate thickness, the longitudinal stretch ratio and the transversal stretch ratio; the measured optical density with the MacBeth TR924 densitometer in transmission mode with a visible filter, the expected optical density, i.e. the optical density calculated using the relationship disclosed in COMPARATIVE EXAMPLE 5 using the theoretical layer thickness values, and the difference between the observed optical density and the optical density expected due to a 2% by weight concentration of the particular titanium dioxide pigment used, ⁇ OD.
• Transversal stretching was then performed on the longitudinally stretched films with a stretch time of 30 s and stretching speed of 1000%/min under the conditions given in Table 25.
• the density, measured thickness and the expected thickness, i.e. thickness if no void-forming based on the extrudate thickness, the longitudinal stretch ratio and the transversal stretch ratio, are also given in Table 25.
• Table 26 gives the measured thickness, the expected thickness, the measured optical density with the MacBeth TR924 densitometer in transmission mode with a visible filter, the expected optical density, i.e. the optical density calculated using the relationship disclosed in COMPARATIVE EXAMPLE 4 using the theoretical layer thickness values, and the difference between the observed optical density and the optical density expected due to a 2% by weight concentration of the particular titanium dioxide pigment used, ⁇ OD.
• the 1100 ⁇ m thick extrudate of INVENTION EXAMPLE 113 having a composition of 2% by weight of titanium dioxide, 100 ppm of UVITEX OB-one [ppm], 15% by weight of SAN 06 and 83% by weight of PET04 was produced as described for EXAMPLES 1 to 58. Stretching in the length direction was carried out for the extrudate as described in EXAMPLES 1 to 58 under four different sets of conditions as given in Table 36. The expected thickness is the thickness based on the extrudate thickness and longitudinal as observed for non-voided films.
• Biaxial stretching reduced the density of the films with the density decrease being greater the lower the transversal stretching temperature.
• the decrease in density is smaller than would be expect simply based on the measured thicknesses compared with the expected thicknesses. This can be partly explained by the combination of two effects: the decrease in the density due to void forming on the one hand being to a degree compensated by the increase in the crystallinity of the polyester matrix due to biaxial stretching on the other.
• Table 38 gives the measured thickness, the expected thickness, i.e. thickness if no void-forming, the optical density measured with a MacBeth TR924 densitometer in transmission mode with a visible filter, the expected optical density, i.e. the optical density calculated using the relationship disclosed in COMPARATIVE EXAMPLE 5 using the theoretical layer thickness values, and the difference between the observed optical density and the optical density expected due to a 2% by weight concentration of the particular titanium dioxide pigment used, ⁇ OD, together with the temperature at which the transversal stretching was carried out.
• Table 39 summarizes the stretch conditions, the thickness, expected thickness, optical density, expected optical density and non-attributable increase in optical density as a result of void-forming for different films obtained at a stretch temperature of approximately 110° C.
• the ca. 1100 ⁇ m thick extrudate of COMPARATIVE EXAMPLE 6 (SP54) with 2% by weight of titanium dioxide, 15% by weight of TPX® DX820, poly(4-methylpentene), 33.3% by weight of PET02 and 49.7% by weight of PET04 having an IPA:TPA molar ratio of 0.0636 was produced as described for EXAMPLES 1 to 58. Stretching in the length direction was carried out for each extrudate as described in EXAMPLES 1 to 58 under the conditions given in Table 47. The expected thickness is the thickness based on the extrudate thickness and longitudinal as observed for non-voided films.

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