Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H5/00—Special paper or cardboard not otherwise provided for
  • D21H5/12—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials
  • D21H5/20—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of organic non-cellulosic fibres too short for spinning, with or without cellulose fibres
  • D21H5/202—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of organic non-cellulosic fibres too short for spinning, with or without cellulose fibres polyolefins
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
  • D21H13/10—Organic non-cellulose fibres
  • D21H13/12—Organic non-cellulose fibres from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H13/14—Polyalkenes, e.g. polystyrene polyethylene

Definitions

• Olefin polymer films particularly ethylene polymer films, are used in commerce in large volume. By reason of their volume usage, the art is continuously seeking (1) olefin polymer films having improved properties and (2) more economical processes for the manufacture of olefin polymer films.
• the web is laid down from an aqueous dispersion of the olefin polymer fibrils and the web is melted by being passed through heated calender rolls.
• the olefin polymer may be a polymer of ethylene or propylene.
• olefin polymer fibrils employed in the practice of the invention constitute a recognized class of materials known and described in the art. Such fibrils are prepared by precipitating an olefin polymer from an organic solvent solution thereof under conditions of high shear. Representative U.S. patents disclosing preparation of such fibrils include the following:
• the olefin polymer fibrils employed in the invention resemble in appearance natural fibres such as cotton anti staple fibres of solution spun polymers such as nylon and the like.
• fibrils When examined microscopically, however, fibrils have grossly irregular shapes, including segments which appear to be film-like in nature. See for example Fig. 4 of U.S. 3,391,499. It's believed possible that these particular physical characteristics may play a role in the function of the olefin polymer fibrils in the present invention.
• the majority of the olefin polymer fibrils employed in the practice of the invention are small in size, with the largest dimension not exceeding about 10 mm.
• the fibrils have a large surface to weight ratio of at least about 2 m 2 /gram as determined by nitrogen absorption/desorpt- ion methods.
• the olefin polymer fibrils employed in the invention are prepared from an ethylene or propylene polymer having a weight average molecular weight of at least about 1 million and preferably at least about 1.5 million. Such polymers will have an intrinsic viscosity of at least 3.5, preferably at least 5.0, and most especially at least 10,0.
• a listing of suitable olefin polymers and olefin polymer mixtures is set forth in U.S. 4,013,751, which description is incorporated herein by reference.
• the web of randomly-dispersed olefin polymer fibrils employed in the invention can be prepared by numerous techniques known and reported in the art.
• the preferred method is to prepare a xater-laid web by the techniques known and used in the paper making arts.
• the fused film is prepared by heating the web to a temperature above the holding point of the olefin polymer and subjecting the web to pressure to compress the melted polymer to form a fused film.
• the pressure required and the duration of the required heating cycle will depend upon a multiplicity of factors including the thickness and bulk density of the web, the melting point of the olefin polymer, and the heat transfer characteristics of the press surfaces.
• the proper combination of temperature and pressure to be employed for a given web in a particular press can be readily established through a few routine experiments.
• a desirable feature of the invention is that the fused film can be prepared at high rates of speed at low cost in a continuous process.
• the random web of fibrils is laid down continuously on a paper making machine.
• the web then is passed over drying rolls and passed through a stack of heated calender rolls.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Casting Or Compression Moulding Of Plastics Or The Like (AREA)
• Compositions Of Macromolecular Compounds (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=25478994

Family Applications (1)

Country Status (2)

Citations (3)

• 1979
  • 1979-06-29 EP EP79301268A patent/EP0009300A1/fr not_active Withdrawn
  • 1979-09-18 JP JP11889879A patent/JPS5542898A/ja active Pending

Patent Citations (3)

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