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
  • D21H5/18—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of inorganic fibres with or without cellulose 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

Definitions

• This invention relates to fibrous sheet composites and a process for the preparation of such composites. More particularly, this invention relates to sheet composites and a process for the preparation thereof, such composites containing asbestiform crystalline calcium M phosphate fibers wherein M is a metal cation selected from the group consisting of sodium and lithium, and mixtures thereof.
• the sheet composites are suitable for use as a replacement or substitute for asbestos sheet composites in applications where fibrous materials are needed.
• Representative uses of the sheet composites are as muffler paper, underlayment felt for vinyl floor coverings, backing for decorative wall covering, gasket papers, roofing paper, sound-deadening paper, pipe wrap, insulation paper, heat deflection papers, electrically resistant paper, board products, and the like.
• U.S. Patent 4,225,343 discloses a nonwoven fibrous, highly filled sheet containing a water dispersible asbestos-free fiber, a film-forming water-insoluble, organic polymer, and a water insoluble, non- fibrous, inorganic filler, and a method of preparation thereof.
• the sheets reportedly are characterized by good runnability on common paper-making equipment and excellent strength properties.
• a flooring felt which reportedly possesses excellent strength properties.
• the felt contains glass fibers, cellulosic fibers, synthetic organic fibers, particulate inorganic filler, latex binder, and calcium hydroxide.
• U.S. Patent 4,395,306 discloses a method for the preparation of reportedly improved nonwoven fibrous mats or sheets from a thickened fibrous suspension of synthetic fibers and an aqueous suspending medium thickened with a synthetic carboxamide polymer. The improvement results from cross-linking the carboxamide polymer by reaction with hypohalite.
• Another object of this invention to provide a process for preparing novel sheet composites containing asbestiform crystalline calcium M phosphate fibers wherein M is a metal cation selected from the group consisting of sodium and lithium, and mixtures thereof, which are highly effective as a replacement or substitute for asbestos sheet composites in applications where fibrous materials are needed.
• sheet composites which comprise:
• novel sheet composites and a process for the preparation of same, are provided which are suitable for use as a replacement or substitute for asbestos sheet composites in applications where fibrous materials are needed.
• These sheet composites comprise:
• the sheet composites are prepared by a process which comprises:
• the asbestiform crystalline calcium M phosphate fibers wherein M is a metal cation selected from the group consisting of sodium and lithium, and mixtures thereof, are high molecular weight phosphates [CaM(PO 3 ) 3 ] n wherein n is a number representing the number of repeating CaM(P0 3 ) 3 units.
• such fibers have an aspect ratio (length-to-average diameter ratio, L/D) of at least 30:1 and an average diameter in the range of from about 0.5 micron ( ⁇ m) to about 20 ⁇ m.
• Preferred fibers are those having an aspect ratio of from about 40:1 to about 100:1 and an average diameter from about 1 ⁇ m to about 10 ⁇ m.
• particularly preferred are calcium M phosphate fibers wherein M is sodium.
• Auxiliary fibers suitable for use to prepare the sheet composites of the instant invention are those which provide the desired physical properties in the final product and permit processing on paper-making equipment.
• Such fibers are water insoluble and water dispersible and advantageously are capable of being fibrillated. Included among such fibers are naturally occurring fibers, synthetic fibers, and mixtures thereof. Usually, water dispersibility is provided by a small amount of ionic or hydrophilic groups or charges which are of insufficient magnitude to provide water solubility. Fibers from natural materials -- wood pulp, for example -- are anionic. Many synthetic fibers, on the other hand, are treated to make them slightly ionic.
• synthetic fibers means auxiliary fibers that are synthesized from simple chemical molecules, and includes inorganic substances extruded in fibrous form and regenerated fibers.
• auxiliary fibers suitable for use in the sheet composites of the instant invention are cellulosic (including lignocellulosic) fibers commonly used in the manufacture of felt and paper.
• Such fibers include those commonly known as wood pulp of the various kinds from hardwood and softwood such as groundwood pulp, steam-heated mechanical pulp, chemi- mechanical pulp, semichemical pulp, and chemical pulp. Specific examples are unbleached (acid) sulfite pulp, bleached (acid) sulfite pulp, unbleached (alkaline) kraft or sulfate pulp, and bleached (alkaline) kraft or sulfate pulp.
• Representative synthetic fibers useful in the practice of the instant invention include glass, rayon, graphite, polyamides (e.g., nylon and aramid), polyesters, polyolefins (e.g., polyethylene and polypropylene), poly(vinyl chloride), and the like.
• Suitable auxiliary fibers preferably will have nominal lengths within the range of from about 0.5 millimeters (mm) to about 20 mm, and most preferably from about 1 mm to about 10 mm, and nominal diameters within the range of from about 3 ⁇ m to about 20 pm, and most preferably from about 4 ⁇ m to about 10 ⁇ m.
• auxiliary fibers are subjected to mechanical action in the presence of water in a manner variously described in the paper-making art as pulping, beating, or refining.
• Cellulosic fibers (naturally occurring auxiliary fibers) useful in the practice of this invention preferably are refined to a Canadian Standard Freeness (CSF) at 0.3% consistency (percentage by weight of dry fibrous material) of from about 300 milliliters (ml) to about 700 ml, most preferably from about 400 ml to about 600 ml.
• CSF Canadian Standard Freeness
• CSF Canadian Standard Freeness
• Synthetic fibers in a manner similar to that employed for cellulosic fibers, are mechanically treated to cause fibrillation. Normally, however, such fibers do not provide the same degree of dispersion as is obtained with cellulosic fibers. As a result, the Canadian Standard Freeness test is not particularly adapted to such materials.
• auxiliary fibers suitable for use in the sheet composites of the instant invention preferred fibers are cellulosic fibers. Most preferred, as previously noted, are cellulosic fibers refined to a Canadian Standard Freeness of 0.3% consistency of from about 400 ml to about 600 ml.
• Water insoluble organic polymeric binder materials useful in the practice of the instant invention are not narrowly critical. Any of the wide variety of natural and synthetic latexes (i.e., aqueous colloidal dispersions) generally known for use in felt and paper manufacture may be used. Conventional styrene-butadiene rubber (SBR) latex is preferred with carboxylated styrene-butadiene rubber (carboxylated SBR) being especially preferred. Other suitable latexes include natural rubber, poly(vinyl acetate), poly(vinyl chloride), polyacrylate, and neoprene latexes. Mixtures of such latexes may also be used.
• SBR styrene-butadiene rubber
• carboxylated styrene-butadiene rubber carboxylated styrene-butadiene rubber
• Other suitable latexes include natural rubber, poly(vinyl acetate), poly(vinyl chloride), poly
• the latexes suitable for use as the water insoluble organic polymeric binder in the instant invention may be used either alone or, as discussed hereinbelow, in combination with conventional curatives, antioxidants, and pigments.
• the water insoluble organic polymeric binder i.e., the latex
• the water insoluble organic polymeric binder can be of any conveniently obtainable particle size. Average particle diameters of from about 1000 Angstroms (R) to about 3000 R are preferred. Especially preferred are particle diameters from about 1500 R to about 2500 ⁇ . Since the latex employed in the practice of the instant invention is diluted during the preparation of the sheet composites, the solid content of the latex as supplied is not critical.
• the phosphate fibers are advantageously treated with a cationic resin prior to admixture with the auxiliary fibers and the water insoluble organic binder in order to ensure compatibility of the nominal ionic charge associated with the phosphate fibers with that of the water insoluble organic binder.
• Cationic resins are resins of high cationic character. Included among such resins are two general types of products -- polymeric amines and quaternary ammonium polymers.
• the former group is comprised of polyethylenimines; high Mannich-substituted polyacrylamides; polymers of cationic monomers, especially poly(dimethylamino-ethyl methacrylate); and polyalkylene polyamines.
• the latter group includes poly(vinylbenzyltrimethyl- ammonium chloride), poly(diallyldimethylammonium chloride), poly(glycidyltrimethylammonium chloride) and poly(2-hydroxypropyl-1,1-N-dimethylammonium chloride).
• the sheet composites will comprise from about 60% to about 95% by weight of the phosphate fibers, from about 1% to about 15% by weight of auxiliary fibers, and from about 5% to about 30% by weight of a water insoluble organic polymeric binder.
• Preferred concentrations, however, for the phosphate fibers will range from about 75% to about 85%, for the auxiliary fibers, from about 3% to about 10%, and for the water insoluble organic polymeric binder, from about 10% to about 20%, all by weight.
• the sheet composites exhibit excellent characterizing properties and paper machine runnability. It will be apparent, however, that other concentrations may be employed in the production of the sheet composites of the instant invention, especially those intended fcr certain specialized end-use applications although, in practice, the stated concentrations are desirable.
• the preparation of the sheet composites of the instant invention can be carried out on handsheet- forming apparatus or, preferably, on common, continuous paper-making equipment such as a Fourdrinier machine, a cylinder machine, suction machines such as a Rotaformer, or on millboard equipment.
• Suitable also for use in preparing the sheet composites of this invention are other well-known modifications of such equipment, for example, a Fourdrinier machine with secondary headboxes or multicylinder machines in which, if desired, different furnishes can be used in the different cylinders to vary the composition and the properties of one or more of the plies which can comprise a finished board.
• the sheet composites of the instant invention are prepared by forming an aqueous dispersion of asbestiform crystalline calcium sodium phosphate fibers having an aspect ratio of at least 30:1 and an average diameter of from about 0.5 ⁇ m to about 20 pm, preferably having an aspect ratio of from about 40:1 to about 100:1 and an average diameter from about 1 ⁇ m to about 10 ⁇ m.
• a cationic resin is added to the aqueous dispersion to provide a nominal positive charge to the phosphate fibers in order to ensure compatibility with the latex which normally is anionic.
• the resulting dispersion is admixed with cellulosic fibers refined to a Canadian Standard Freeness of from about 300 ml to about 700 ml, preferably from about 400 ml to about 600 ml, and a water-insoluble organic polymeric binder.
• the aqueous dispersion is formed or prepared to provide a sheet composite containing (on a dry weight basis) from about 65% to about 90%, most preferably from about 70% to about 85%, of phosphate fibers, from about 3% to about 7% of cellulosic fibers (auxiliary fibers), and from about 10% to about 20% of latex (the water-insoluble polymeric binder).
• the aqueous dispersion is distributed and drained on a porous substrate such as a wire to form a wet web or wet sheet composite which is subsequently pressed and dried.
• additional water may be added as necessary to reduce the consistency of the resulting furnish to a value suitable for paper making.
• This value may conveniently range from about 0.1% to about 6%, preferably from about 1% to about 3%.
• Part of the water of dilution advantageously is white water, or process water, recycled from later steps in the sheet-making process. Alternatively, or additionally, some of the white water can be used as necessary in any required refining step for the auxiliary fibers.
• the temperatures employed through the step of forming the wet web usually is in the range from about 20° C (68° F) to about 40° C (104° F) although temperatures outside the stated range can be employed so long as such temperatures are above the freezing point of the aqueous dispersion and are below the temperature at which the latex polymer being employed would soften unduly. Temperatures above ambient conditions may at times be advantageously employed to promote faster drainage.
• Such materials include antioxidants; sizings; various hydrocarbons and natural waxes, particularly in the form of anionic or cationic emulsions; particulate inorganic, essentially water-insoluble fillers having a particle diameter less than 50 ⁇ m such as titanium dioxide, amorphous silica, zinc oxide, barium sulfate, calcium carbonate, calcium sulfate, aluminum silicate, clay, magnesium silicate, diatomaceous earth, aluminum hydroxide (aluminum trihydrate), magnesium carbonate, partially calcined dolomitic limestone, magnesium hydroxide, and mixtures thereof; cellulose derivatives such as carboxymethyl cellulose and carboxyethyl cellulose; water soluble organic dye stuffs, water-insoluble but water dispersible coloring pigments such as carbon black, vat colors, and sulfur colors; strength improving resins such as melamine- formaldehyde resins, urea-formaldehyde resins, aminopolyamide-epichlorohydrin resins, and polymeric
• the thickness of the sheet composites of the instant invention can vary from about 7.62 x 10 -3 cm (3 mils) to about 3.175 x 10 -1 cm (125 mils), the preferred value depending upon the proposed use of the sheet composites. In general, however, the thickness will range from about 3.81 x 10 cm (15 mils) to about 1.65 x 10- 1 cm (65 mils).
• the sheet composites of the instant invention possess excellent strength properties, smooth surface characteristics, dimensional stability, resistance to microbiological growth, resistance to moisture effects, and paper machine runnability.
• the sheet composites are processable into sheet vinyl flooring in a conventional manner.
• the melt was held at 1000° C for 24 hr, cooled to 740° C, at which time several small seed crystals of [CaNa(PO 3 ) 3 ] n were added to the surface of the melt which was held at 740° C for 72 hr to crystallize.
• the temperature was reduced to 720° C and held for an additional 72 hr to complete the crystallization, after which the crystallized mass was slowly cooled to room temperature and removed from the crucible.
• the crystallized mass was broken apart, passed through a mechanical jaw crusher, and then fiberized by dry milling in an air classification mill. Fibers from several different batches were combined to provide a composite sample of 2.27 x 10 2 kg (500 lb) of fibers for testing.
• the fibers had an average aspect ratio of 64.5, an average diameter of 2.09 ⁇ m, and a surface area of 6773 cm 2 / g .
• the phosphate fiber sheet composites were prepared by use of a Four- dinier Paper Machine having (a) a 91.44-centimeter (36-inch) wide plastic wire, (b) a headbox equipped with a manifold type inlet, homogenizer and distributor rolls, and a Neilson slice, (c) a suction couch roll, (d) a straight-through plain press, and a plain reversing press, the rolls being cast iron with rubber and stonite covers, (e) a dryer section consisting of 7 and 5 driers with integrally cast journals and 2 felt driers on the bottom and top first section felts and (f) a calendar stack consisting of eight rolls with the intermediate rolls bored for steam.
• the machine was also equipped with a 91.44-cm (36-inch) diameter Pope type reel with a 91.44-cm face capable of winding rolls up to 101.6 cm (40 inches) in diameter.
• aqueous slurry was charged in series 13.1 kg [28.8 lb, 33.7 1 (8.9 gal)] of a wet strength paper additive (a cationic thermosetting polyamine-epichlorohydrin resin sold commercially as Santo-Res CM by Monsanto Company), 56.7 kg [125 lb, 1.14 x 10 2 1 (30 gal)] of an aqueous dispersion of a carboxylated styrene-butadiene rubber latex [in admixture with 3 percent of polymeric hindered phenol-thioester blend antioxidant (available commercially from Textile Rubber & Chemical Co.
• a wet strength paper additive a cationic thermosetting polyamine-epichlorohydrin resin sold commercially as Santo-Res CM by Monsanto Company
• T-4114 having 46 percent solids and an average particle diameter of 1900 R (available commercially from Dow Chemical Company as XD-30192.00), and 10.0 kg (22 lb) of common bleached softwood kraft refined to a Canadian Standard Freeness of 485 ml.
• the resulting furnish or aqueous dispersion was pumped from the machine chest through a flow controller valve to the suction of a fan pump where the thick furnish was diluted with white water from the wire to the required paper-making consistency. (A consistency of about 1% to about 2.5% was employed although higher consistencies, for example, about 4% to about 6% may be employed, if desired.)
• the diluted furnish was pumped from the fan pump to the headbox of the Fourdrinier Machine through a five-pipe manifold inlet.
• the furnish from the headbox was fed onto the wire moving at 12.7 cm/sec (25 ft/min) where white water drained to form a wet sheet from which additional water was removed by means of the suction boxes before the sheet was removed from the wire at the suction couch roll.
• the sheet was fed through the dryer and calendar stack and collected as rolls.
• the rolls were slit and trimmed to yield three rolls of phosphate fiber sheet composite -- 1 roll, 38.1 cm wide x 83.8 m long (15 in wide x 275 ft long); 1 roll, 38.1 cm wide x 53.3 m long (15 in wide x 175 ft long); and 1 roll, 33.02 cm wide x 83.8 cm long (13 in wide x 275 ft long, all having a nominal thickness of 7.62 x 10 -2 cm (30 mils).
• Property data for the sheet composites are tabulated in Table 1.

Landscapes

• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Paper (AREA)

Applications Claiming Priority (4)

Publications (1)

Family

ID=27103624

Family Applications (1)

Country Status (3)

Citations (4)

• 1985
  • 1985-12-23 BR BR8506447A patent/BR8506447A/pt unknown
  • 1985-12-23 EP EP85870197A patent/EP0187131A1/fr not_active Withdrawn
  • 1985-12-23 AU AU51564/85A patent/AU5156485A/en not_active Abandoned

Patent Citations (4)

Also Published As

Similar Documents

Legal Events