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
  • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
  • D21H13/36—Inorganic fibres or flakes
  • D21H13/38—Inorganic fibres or flakes siliceous
  • D21H13/40—Inorganic fibres or flakes siliceous vitreous, e.g. mineral wool, glass fibres
• • 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
  • D21H13/36—Inorganic fibres or flakes
  • D21H13/38—Inorganic fibres or flakes siliceous
  • D21H13/44—Flakes, e.g. mica, vermiculite
• • 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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
• • 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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/36—Polyalkenyalcohols; Polyalkenylethers; Polyalkenylesters
• • 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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/37—Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
• • 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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/63—Inorganic compounds
  • D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
  • D21H17/68—Water-insoluble compounds, e.g. fillers, pigments siliceous, e.g. clays

Definitions

• This invention provides non-asbestos alternatives to asbestos papers.
• Asbestos papers contain asbestos fibres as the predominant raw material, these fibres being bound together with small amounts of hydrolysed starch, acrylic resin, or polyvinyl acetate to provide the necessary strength and flexibility.
• Such papers find use for a variety of purposes, e.g. as high temperature flexible insulation in electrical equipment. They are commonly made in the form of flexible sheet of thickness 0.1-1.5 mm. on conventional paper-making machines such as the Fourdrinier. In the process an aqueous slurry of the ingredients which are to compose the product is progressively dewatered as a layer on a water-permeable conveyor (usually of wire mesh), the dewatered layer being subsequently compressed and dried.
• a water-permeable conveyor usually of wire mesh
• the present invention provides non-asbestos flexible sheet material which has flexibility and toughness such that it is specially suited to conversion to corrugated form, suitable for use as thermally insulating material for pipes, domestic hot water boilers and the like.
• non-asbestos flexible sheet material of thickness 0.1-1.5 mm. comprises a matrix of unfired ball clay which is reinforced by organic web-forming fibres and by either
• Ball clay provides a flexible cohesive matrix.
• Ball clay is a fine-grained, highly plastic, mainly kaolinitic sedimentary clay.
• 'kaolinitic' and 'kaolinite' are mineralogical ones, indicating chemical composition and chemical structure; they are not to be confused with the term 'kaolin', used to denote a highly refractory clay which approaches the mineral kaolinite in chemical composition and structure but which - by contrast with ball clay - is hardly plastic at all.
• Various types of ball clay have varying proportions of kaolinite, micaceous material, and quartz, with small amounts of organic matter and other minerals.
• Ball clays are used mainly in the manufacture of pottery and refractories, in admixture with other clays (such as the kaolin mentioned earlier) to impart plasticity to them and to increase the green strength of the unfired ware.
• the function of the organic web-forming fibres is primarily to enable the paper to be formed on conventional paper-making machinery, but additionally those fibres impart strength to the ball clay matrix of the finished paper, just as do the vitreous fibres derived from wool-form material or the non-fibrous charged-layer-silicate mineral (the primary reinforcement).
• the organic web-forming fibres are preferably cellulose. fibres, but may alternatively be polyethylene or polypropylene fibres of the kind commercally available under the name PULPEX. In the preparation of the aqueous slurry to be dewatered, the web-forming fibres are employed at a freeness of 60-90° Schopper-Riegler.
• vitreous fibres derived from wool-form material provide the primary reinforcement
• the material may be mineral wool or glass wool. If glass wool is used, it is preferably employed in a form which has been treated with a silane coupling agent (e.g. gamma-aminopropyl triethoxysilane).
• a silane coupling agent e.g. gamma-aminopropyl triethoxysilane.
• the wool-form vitreous fibre material employed has fibres which are predominantly in the range 0.25-5mm in length.
• the particles should be capable of passing a sieve of aperture 250 um.
• the non-fibrous charged-layer-silicate mineral employed is preferably a mica or a chlorite.
• the chlorites have structures containing infinite two-dimensional ions of opposite electrical charge, the negatively charged layers having compositions ranging from [Mg 3 (AlSi 3 O 10 )(OH) 2 ]- to [Mg 2 Al(Al 2 Si 2 O 10 )(OH) 2 ]-, the positively charged layers having the composition [Mg 2 Al(OH) 6] +.
• Such non-fibrous charged-layer-silicate minerals are to be distinguished from non-fibrous layer silicate minerals such as kaolinite, talc and pyrophyllite, where the infinite 2-dimensional layers (e.g. A1 2 (OH) 4 Si 2 O 5 in kaolinite) are uncharged.
• the binder employed consists essentially of a synthetic resin, said resin being of the acrylic or polyvinyl acetate variety.
• Suitable acrylic resins are available in the form of synthetic polymeric latices consisting of a fine suspension in water of a copolymer based on an acrylic ester as the principal monomer.
• Suitable polyvinyl acetate resins are also available as synthetic resin emulsions consisting of a fine suspension in water of a polymer based on vinyl acetate.
• the paper may also contain a small proportion, suitably in the range of 1-10% of rayon fibres, to impart green strength to the sheet material between the dewatering and drying operations, and also to impart additional strength to the finished paper.
• the density of the paper will ordinarily be within the range 700-1100 kg/m 3 , its tensile strength at least 3 MPa and its burst strength at least 40 KPa.
• the paper can be corrugated in a corrugating machine of standard construction, and withstands very well the stresses imposed by passage between the corrugating rollers of the machine.
• the stock (slurry) of A above was made into flexible sheet material is an entirely conventional way on a Fourdrinier flat wire paper machine, such as is described in chapters 10 and 11 of "Paper and Board Manufacture” by Julius Grant, James H. young, and Barry G. Watson (Publishers: Technical Division, the British Paper and Board Industry Frederation, London 1978).
• the slurry is progressively dewatered as it travels on the water-permeable conveyor of the machine, and the dewatered material is consolidated by pressing between rollers, and then dried to low moisture content (suitably 2% by weight).
• the finished paper can at once or .later be submitted to a corrugating process as described, for example, in Chapter 24 (page 262ff) of "Paper - Its Merchanting and Usage", Editor S. Carter Gilmour (publ. The National Association of Paper Merchants, with Longmans, Green & Co.).

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• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Dispersion Chemistry (AREA)
• Paper (AREA)

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Citations (3)

• 1981
  • 1981-11-26 EP EP81305598A patent/EP0055033A1/fr not_active Withdrawn
  • 1981-11-30 ZA ZA818291A patent/ZA818291B/xx unknown
  • 1981-12-18 JP JP56205047A patent/JPS57128299A/ja active Pending

Patent Citations (3)

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