Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • 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
  • B29C55/023—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets using multilayered plates or sheets
  • B29C55/026—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets using multilayered plates or sheets of preformed plates or sheets coated with a solution, a dispersion or a melt of thermoplastic material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D7/00—Producing flat articles, e.g. films or sheets
  • B29D7/01—Films or sheets
• • 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
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/0427—Coating with only one layer of a composition containing a polymer binder
• • 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
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/043—Improving the adhesiveness of the coatings per se, e.g. forming primers
• • 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
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/048—Forming gas barrier coatings
• • 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
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/052—Forming heat-sealable coatings
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/62—Record carriers characterised by the selection of the material
  • G11B5/73—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
  • G11B5/739—Magnetic recording media substrates
  • G11B5/73923—Organic polymer substrates
  • G11B5/73927—Polyester substrates, e.g. polyethylene terephthalate
  • G11B5/73929—Polyester substrates, e.g. polyethylene terephthalate comprising naphthalene ring compounds, e.g. polyethylene naphthalate substrates
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/62—Record carriers characterised by the selection of the material
  • G11B5/73—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
  • G11B5/739—Magnetic recording media substrates
  • G11B5/73923—Organic polymer substrates
  • G11B5/73927—Polyester substrates, e.g. polyethylene terephthalate
  • G11B5/73931—Two or more layers, at least one layer being polyester
• • 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
• • 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

Definitions

• This invention relates to improved biaxiaUy oriented copolyester films, especially PENBB films.
• this invention relates to improving the surface, tensile strength, modulus and dimensional stability of thermoplastic films.
• polyester films do not readily retain printing ink im ⁇ pressions nor do they tend to form strong bonds to coatings for other films to be heat sealed to them. Polyester films also tend to acquire static char- ges.
• PET films are very useful for wrapping, especially when oriented. PET films are also used as a base for, e.g. photo ⁇ graphic films, magnetic recording tapes or impact or thermal transfer printer ribbons. However, there is still a need for further improvement of the base films' tensile strength, modulus and dimensional stability, which then would allow the use of thinner film, which in turn would increase the capacity. In addition, PET films show poor adherance to printing inks, magnetic, photogra ⁇ phic coatings and the like. It was therefore an object of the present invention to provide a thermoplastic base film with improved tensile strength, stiffness (tensile modulus), dimensional stability and strong adherance to coc tings.
• U.S. Patent No. 3,008,934 discloses copolyesters containing as acid derived units 4,4'-bibenzoate and a host of other dicarboxylates including 2,6-naphthalic dicarboxylate. It also discloses oriented fibers and films prepa ⁇ red from these copolyesters, however, biaxiaUy oriented PENBB films are not disclosed or envisioned. In particular, those films with improved stiffness
• thermo- stability tensile modulus
• UV stability tensile strength
• hydrophobicity tensile strength
• dimensional stability tensile strength
• impermeability toward gases in comparison to PET film are not disclosed in U.S. Patent No. 3,008,934.
• one or both surfaces of an orient- able PENBB film are covered with a thermoplastic polymer and the coated film is then stretched to produce a biaxiaUy oriented coated PENBB film, the total thickness of the coating layer being at least 50 times thinner than the thick ⁇ ness of the base layer.
• the final covering of thermoplastic polymer of this invention may be very thin, i.e. down to molecular thicknesses. There may even be gaps in the coverings but, of course, it is a requirement that the coverings should provide a substantially uniform effect over the film.
• Very thin coverings are best applied to the PENBB films as solution or dispersion. Any suitable coating technique may be used; a convenient method of applying a thin liquid coat is by means of roller coating, spray coating, gravure coating, slot coating, or immersion coating. They are most easily applied at room temperature or at not unduly elevated temperature, so that the solvent or dispersion medium does not tend to evaporate during the application stage.
• Dispersions in water are the least expensive form of providing the thermoplastic polymer and these can give uniform coverings if the polymer is fluid at the drawing temperature and forms a film.
• Concentrated aqueous dispersions are preferred, i.e. those containing 30 percent dry weight of the polymer because the energy required to heat the film to its stretching temperature is then normally sufficient to evaporate the small amount of water in the covering.
• These dispersions do not usually contain more than 55 percent dried weight of polymer because of the practical difficulties of preparing stable, mobile dispersions with a higher dry weight content, in some cases it may, however, be necessary to decrea ⁇ se the solid content of the dispersions to obtain the desired thinness of covering.
• the coverings according to this invention on the drawn PENBB film are usually at least 3 nm thick.
• the total thickness of the coverings is preferably at least 200 times thinner than the PENBB base layer if both sides are covered, and 400 times thinner if only one side is covered.
• thermoplastic polymers for the coverings according to this invention include polyethylene, polyvinylacetate, hydrolyzed and partially hydrolyzed polyvinylacetate, copolymers of butadiene with, for instance, acrylonitrile or methylmethacrylate, copolymers of styrene with, for instance, butadiene, methacrylic acid, acrylic acid, or esters thereof and low molecular weight poiyamides.
• Very suitable thermoplastic polymers according to this invention are the copolymers of vinylidene chloride, for instance those with one or more of acrylonitrile, vinyl chloride, alkyl acrylates, itaconic acid, methacrylic acid and acrylic acid.
• thermoplastic polymers for use for these coverings are polyurethanes, polystyrenes and aliphatic acid salts such as alkali metal salts of unsaturated fatty acids having from 10 to 18 carbon atoms, or alkali earth metal salts of fatty acids having from 10 to 18 carbon atoms.
• Suitable polyurethanes are for instance those wherein the carboxyl groups are introduced by esterifying the terminal hydroxyl groups and amidizing any terminal amine groups of the poiyurethane with a dicarbox- ylic acid anhydride.
• the most generally useful thermoplastic polymers as coverings are those having at least one carbon atom with a polar substituent per every 6 carbon atoms of the polymer chain.
• Polyethylene may be used though it normally requires an oxidation treatment, e.g. a corona treatment, before it is suitable for bonding printing inks or other coatings on the base film.
• PENBB as mentioned hereinbefore is a copoiyester containing as acid- derived unit at least 5 mole percent of a radical of the formula
• PENBB is a copoiyester wherein at least 80 mole percent of the acid derived units (NBB) consist of bibenzoate (20 to 80 mole percent, preferably 40 to 60 mole percent) and naphthalate (80 to 20 mole percent, preferably 60 to 40 mole percent). The remaining 20 or less mole percent may consist of other acid derived units, which e.g.
• the diol-derived units Preferably at least 80 mole percent of the diol-derived units consist of -O(CH 2 ) 2 -O-units. The remaining 20 or less mole percent consist of other diol-derived units, which e.g. may also affect the melting point or the crystallization kinetics. It may also be desirable to replace minor amounts of the acid- and/or diol-derived units with hydroxycarboxylic-acid-derived units, e.g. such derived from p-hydroxyben- zoic acid.
• the inherent viscosity of the polymer is above 0.5 dl/g and preferably between 0.55 and 1 .7 dl/g (measured at a concentration of 0.1 weight percent in a 1 : 1 mixture by weight of pentafluorophenol and hexafluoroiso- propanol at 25 * C).
• the copoiyester is obtained by polycondensation of the corresponding mixture of diacids or lower dialkyl diesters and the corresponding diol. Both components should preferably be employed in equimolar ratios. It may, however, be advantageous to employ one of the components -- especially the diol - in excess, for instance in order to influence the reaction kinetics or to serve as a solvent.
• the polycondensation is carried out according to known processes used, e.g. in the production of polyethylene terephthalate (PET).
• Useful stabilizers and catalysts can be polyphosphates, triorganyl phosphates, antimony trioxi- de or tetraalkoxy titanate(IV) or mixtures of triphenylphosphate and antimony trioxide.
• a preferred process for the production of such copolyesters is described in U.S. Patent Application Serial No. 07/735,553 which is incorpo ⁇ rated herein by reference.
• a further increase in molecular weight can be achieved by solid phase polycondensation at a temperature just below the melting point under vacuum, or a stream of dry air or inert gas.
• the polymer melt is extruded through a die onto a chill roll where it solidifies, is then biaxially oriented, heat set, optionally post treated and wound on a roll.
• a chill roll For a multilayer film known methods for coextrusion, in-line or off-line coating can be used.
• the solidified film as extruded on the chill roll should be obtained in an essentially amorphous state.
• the melt film must be pinned to the chill roll by a known method such as electrostatic pinning or vacuum, air knife or the like.
• the biaxial orientation of the film is achieved by stretching the film at elevated temperature in the machine (MD) and transverse direction (TD). This stretching can be either simultaneous or sequential.
• the first stretching step can be in either MD or TD, followed by stretching in the other direction.
• the orientation in MD can also be achieved in several steps, either one after another prior to stretching in TD, or before and after the TD stretching.
• Preferred temperatures for stretching lie bet ⁇ ween the glass transition temperature and about 30 * C above the cold cry ⁇ stallization temperature of the PENBB copolymer composition in use (both temperatures can easily be measured on amorphous films by DSC).
• the total stretch ratios ( ⁇ ) in MD and TD lie between 1 : 2 and 1 : 10, preferably between 1 : 2.5 and 1 : 5.
• the product of the total stretch ratios should be between 1 to 30 preferably between 5 to 20.
• Biaxial drawing is performed such that the birefringeance is ⁇ 0.2, preferably ⁇ 0.1 to ensure adequately isotropic properties.
• Birefringeance as mentioned herein is the absolute value of the difference between the maximum and minimum refractive indices in the plane of the film, as measured on common instruments such as Abbe refractometer, optical bench or compensators.
• relaxation steps can be included in the orientation and heat setting processes.
• the heat setting takes place at a temperature between the cold crystal- lization temperature and the melt temperature of the copolymer composition.
• the film Prior to coating the PENBB film surface with the thermoplastic coating composition, the film may be surface treated in a conventional manner by exposure to, e.g., an electric corona discharge, plasma, or flame treatment. It is preferred to apply the covering layer before the film is drawn transversely, i.e. after the longitudinal stretching step. This process is prefer ⁇ red to coating the PENBB film before drawing in either direction because coating before any drawing involves drawing the film at an elevated tempera ⁇ ture between tensioning rollers running at different speeds and when such a process is applied to coated film there is a tendency for the coating to stick to the drawing rolls.
• an electric corona discharge, plasma, or flame treatment It is preferred to apply the covering layer before the film is drawn transversely, i.e. after the longitudinal stretching step. This process is prefer ⁇ red to coating the PENBB film before drawing in either direction because coating before any drawing involves drawing the film at an elevated tempera ⁇ ture between tensioning rollers running at different speeds and when such a process is applied to coated film there is a tendency for the
• the coated PENBB films according to this invention have the advantage that, as the coverings are so thin, the PENBB films can be recovered by the normal method of scrap recovery involving, for instance, compression and melting, without the thermoplastic polymer of the covering causing a significant contamination of the PENBB.
• This is an important ad ⁇ vantage because, in the production of oriented films, scrap film is inevitably produced and the recovery of this scrap is necessary for economy in the pro- duction of oriented films.
• the process according to this invention has the advantage of simplicity and, therefore, cheapness.
• the coverings of this invention may be applied, for example, to improve the retention of printing ink impressions to the film or the covering may form bonds of improved strength with further coatings embossed on the films.
• the covering may also serve to render the film heat sealable to itself and other thermoplastic polymer layers, this being of great importance if the film is used for packaging purposes.
• Suitable covered surfaces of the PENBB films according to this invention may be used as a base on which various top coatings may be applied, e.g. coatings to render the film heat sealable, barrier coatings to form laminated films of low permeability to gases and vapors, e.g.
• coatings of vinylidene chloride copolymers coatings containing ferroma ⁇ gnetic materials to form magnetic recording tapes, coatings to form photogra ⁇ phic films, the photosensitive layer containing either, for instance, silver or diazo compounds sensitive to light, coatings to form pressure sensitive adhesive films, coatings to form impact or thermal ribbon for printers.
• These films show the desired combined features of tensile strength, stiffness (tensile modulus), dimensional stability and excellent adhesion toward other functional layers as mentioned above.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Dispersion Chemistry (AREA)
• Laminated Bodies (AREA)

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• 1992
  • 1992-12-09 WO PCT/US1992/010683 patent/WO1994013480A1/en not_active Application Discontinuation
  • 1992-12-09 EP EP93901008A patent/EP0674590A4/de not_active Withdrawn

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