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
  • 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
  • D21H17/675—Oxides, hydroxides or carbonates
• • 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
  • D21H17/35—Polyalkenes, e.g. polystyrene
• • 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
  • D21H17/41—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups
  • D21H17/42—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups anionic
  • D21H17/43—Carboxyl groups or derivatives thereof
• • 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
• • 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
  • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
  • D21H23/76—Processes or apparatus for adding material to the pulp or to the paper characterised by choice of auxiliary compounds which are added separately from at least one other compound, e.g. to improve the incorporation of the latter or to obtain an enhanced combined effect
  • D21H23/765—Addition of all compounds to the pulp

Definitions

• the invention is concerned with pigmented, non-woven, fibrous sheets, particularly highly filled sheets having a low fiber content.
• Paper has been described as a sheet material made up of many small discrete fibers (commonly cellulosic) bonded together. Small amounts of latex have been used in the paper making process. Fillers have also been used to improve certain properties of the paper even though the strength of the sheet is thereby reduced. The amount of fillers heretofore used in paper making processes on common equipment such as the Fourdrinier machine generally has not been greater than 30 or 35 percent of the total dry weight of the sheet, although up to 40 percent has been disclosed as operable. The retention of fillers in the sheet during formation has been recognized as a significant problem.
• the process and product of this invention includes the combination of a water-dispersible fiber, a film-forming, water-insoluble, organic polymer and an inorganic filler in the form of a water-laid sheet.
• One method of forming such a sheet is by:
• the preferred highly filled, water-laid, fibrous, asbestos-free sheets are suitable as a replacement or substitute for asbestos sheets in many of their applications but are not restricted to such uses.
• Representative uses of the sheets are as muffler paper, underlayment felt for vinyl floor covering, gasket papers, roofing paper, , sound-deadening paper, pipe wrap, insulation paper, heat deflection papers, cooling tower packing, electrically resistant paper and board products.
• the product and process of this invention requires a water-dispersible fiber, a film-forming, water-insoluble, organic polymer and a finely-divided, substantially water-insoluble, non-fibrous, inorganic filler.
• a flocculating agent also is required.
• the fiber is any water-insoluble, natural or synthetic water-dispersible fiber or blend of such fibers.
• water-dispersibility is provided by a small amount of ionic or hydrophilic groups or charges which are of insufficient magnitude to provide water-solubility.
• Either long or short fibers, or mixtures thereof, are useful, but short fibers are preferred.
• Many of the fibers from natural materials are anionic, e.g., wood pulp.
• Some of the synthetic fibers are treated to make them slightly ionic, i.e., anionic or cationic.
• Fibers chopped glass, blown glass, reclaimed waste papers, cellulose from cotton and linen rags, mineral wool, synthetic wood pulp such as is made from polyethylene, straws, ceramic fiber, nylon fiber, polyester fiber, and similar materials are useful.
• Particularly useful fibers are the cellulosic and lignocellulosic fibers commonly known as wood pulp of the various kinds from hardwood ; and softwood such as stone ground wood, steam-heated mechanical pulp, chemimechanical pulp, semichemical pulp and chemical pulp. Specific examples are unbleached sulfite pulp, bleached sulfite pulp, unbleached sulfate pulp and bleached sulfate pulp.
• the film-forming, water-insoluble, organic polymer useful in the practice of this invention is natural or synthetic and may be a homopolymer, a copolymer of two or more ethylenically unsaturated monomers or a mixture of such polymers. Particularly for ease of processing to make the product and for limiting the loss of pollutants to the surroundings, it is generally advantageous that the polymer is in the form of a latex, i.e., an aqueous colloidal dispersion.
• Organic polymers are natural rubber, the synthetic rubbers such as styrene/butadiene rubbers, isoprene rubbers, butyl rubbers and nitrile rubbers and other rubbery or resinous polymers of ethylenically unsaturated monomers which are film-forming, preferably at room temperature or below, although in a particular instance a polymer may be used which is film-forming at the temperature used in preparing that sheet.
• Non--film-forming polymers may be used in blends provided that the resulting blend is film-forming. Polymers which are made film-forming by the use of plasticizers also may be used.
• polymers which are readily available in latex form are preferred -- especially hydrophobic polymers which are prepared by emulsion polymerization of one or more ethylenically unsaturated monomers.
• hydrophobic polymers which are prepared by emulsion polymerization of one or more ethylenically unsaturated monomers.
• Representative of such latexes are those described in United States Patent No. 3,640,922, David P. Sheetz, from column 1, line 61, to column 2, line 34. That passage (particularly column 2, lines 2-9) indicates a preference for latexes of polymers and copolymers not having a substantial proportion of hydrophilic groups.
• the latexes preferably have some ionic hydrophilic groups but must be devoid of sufficient non-ionic colloidal o stabilization which would interfere with formation of the fibrous agglomerate.
• non-ionic, colloidal stabilization could be provided by non-ionic emulsifiers or by the presence of copolymerized monomers having the kinds of hydrophilic groups as are found in non-ionic emulsifiers, for example, hydroxyl and amide groups.
• monomers having such hydrophilic groups are polymerized constituents of the latex polymers, such monomers will be present in small proportions such as less than about 10 percent, usually less than about 5 percent of the polymer weight for best results.
• non--ionic emulsifiers can be tolerated in some compositions, their use ordinarily is not advantageous and they should not be used in amounts sufficient to interfere with the destabilization step of the process.
• Latex compositions for use in this invention are selected from latexes in which a polymer of the foregoing description is maintained in aqueous dispersion by ionic stabilization.
• ionic stabilization is obtained, for example, by use of an ionic surfactant or small amounts of a monomer containing an ionic group during emulsion polymerization to prepare the latex.
• the small amount of ionic groups which are bound to the polymer generally will provide less than about 0.7 milliequivalent of charge per gram of polymer in the latex.
• the latex component for this invention have a charge bound to the polymer of from about 0.03 to about 0.4, especially from about 0.09 to about 0.18, milliequivalent per gram of polymer in the latex, particularly when the charge is provided by carboxylic salt groups.
• bound to the polymer with respect to ionic groups or charges refers to ionic groups or charges which are not desorbable from the polymer.
• Materials containing such ionic groups or charges may be obtained as noted above by copolymerization of a monomer containing ionic groups or by other ways such as grafting, by attachment (through covalent bonds) of catalyst fragments to the polymer, especially sulfate groups from persulfate catalysts, or by the conversion to ionic groups of non-ionic groups already attached to the polymer by covalent bonds.
• the ionic groups advantageously are the carboxyl salt groups, especially the alkali metal and ammonium carboxylate groups, or quaternary ammonium salt groups, but other anionic and cationic groups are useful; for example, sulfate, sulfonate and amino groups. Carboxyl salt groups are especially advantageous.
• the ionic stabilization is provided by adsorbed ionic surfactants. Small amounts of ionic surfactant can be used with latexes having bound ionic groups but increasing amounts of surfactants above the amounts required for adequate stabilization tend to make proper selection of other components of the system more critical and complicate the formulation.
• Anionic and cationic surfactants are well known in the art and suitable materials of those classes can be selected, for example, from among those listed in the annual issues of "McCutcheon's Detergents and Emulsifiers" such as the 1973 issue, published by McCutcheon's Division, Allured Publishing ° Corporation, Ridgewood, NJ. Examples of non-ionic surfactants are also provided in the above-noted reference.
• the especially preferred latexes (i.e., latexes having from about 0.09 to about 0.18 milliequivalent of bound charge per gram,of polymer) generally work best in the process and provide overall the best composite sheet.
• these especially preferred latexes are used in the process, the procedure for the colloidal destabilizing step as well as the selection of the amount and kinds of the other ingredients within the limits described herein are less demanding.
• observation of the behavior during the process provides guidance for selections of the various other components for use when it is desired to use latexes within the preferred and operable limits but outside the especially preferred limits.
• the appearance and nature of the resulting flocculated material when using the especially preferred latexes will guide the skilled in the art in the critical selection of the other components when a latex outside the especially preferred but within the operable limits is used -- especially with the higher bound charge latex.
• the charge/mass ratio expressed herein as milliequivalents of charge per gram of polymer in the latex, does not necessarily (and generally does not) correspond, for example, to the proportion of milliequivalents of monomer containing an ionic group which is copolymerized with the non-ionic, hydrophobic monomers by emulsion polymerization to form the latex.
• the ionic monomer may homopolymerize or copolymerize to form varying amounts of water-soluble polymers, or (3) in some instances the ionic monomer does not polymerize as completely as the other monomers.
• the proportion of the ionic monomer in relation to the total monomer increases, the proportion of the ionic groups of the ionic monomers which are on the surface of the particle decreases and the amount buried within the latex particles or which forms ionic water-soluble polymers increases.
• Latexes of any conveniently obtainable particle size are useful in the practice of this invention but average particle diameters of from about 1000 to about 2600 angstroms are preferred -- especially from about 1200 to about 1800 angstroms. Since the latex is diluted during the process, the solids content of a latex as supplied is not critical.
• a chain transfer agent of known kinds such as, but not restricted to, the various long chain mercaptans, bromoform, and carbon tetrachloride.
• the fillers which are used in the practice of this invention are finely-divided, essentially water--insoluble, inorganic materials.
• Such materials include, for example, titanium dioxide, amorphous silica, zinc oxide, barium sulfate, calcium carbonate, calcium sulfate, aluminum silicate, clay, magnesium silicate, diatomaceous earth, aluminum trihydrate, magnesium carbonate, partially calcined dolomitic limestone, magnesium hydroxide and mixtures of two or more of such materials.
• Magnesium hydroxide runs particularly well on common, available paper-making equipment to form a product having good properties, contributes to flame resistance and to resistance to microbiological attack and is preferred.
• the particle size of the fillers is such that the preponderant proportion i is below 50 microns in diameter.
• the average diameter is generally above about 0.1 micron and preferably is from about 0.1 to about 20 microns.
• the fillers should be free of asbestos contaminants.
• a flocculating agent or destabilizing agent (sometimes also called a deposition aid) is highly advantageous.
• Such flocculating agents are water-dispersible, preferably water-soluble, ionic compounds or polymers, i.e., compounds or polymers having a positive or a negative charge.
• a flocculating agent is chosen which has a charge opposite in sign to the ionic stabilization of the latex. If the latex has a negative charge, the flocculating agent will have a cationic charge and vice versa.
• combinations of two or more flocculating agents are used, not all of them are necessarily opposite in charge to the initial charge of the latex.
• Representative flocculants are cationic starch; water-soluble, inorganic salts such as alum, aluminum sulfate, calcium chloride and magnesium chloride; an ionic latex having a charge opposite in sign (+ or -) to that of the binder latex, e.g., a cationic latex or an anionic latex; water-soluble, ionic, synthetic, organic polymers such as poly- ethylenimine and various ionic polyacrylamides such as carboxyl-containing polyacrylamides; copolymers of acrylamide with dimethylaminoethyl methacrylate or diallyldimethyl ammonium chloride; polyacrylamides modified other than by copolymerization to have ionic groups; and combinations of two or more of the above, added simultaneously or in sequence. Quaternized polyacrylamide derivatives are especially advantageous when the latex which is used is anionic. Polymeric flocculants are preferred because they are more efficient, tend to produce less water-sensitive products and provide better shear
• the preferred process for making the products of this invention is particularly adaptable to be carried out on handsheet-forming apparatus or common, continuous paper-making equipment such as a Fourdrinier machine, a cylinder machine, suction machines such as a Rotaformer, or on millboard equipment.
• 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 the practice 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 several plies which can comprise a finished board.
• the preferred process requires the following steps:
• the fibrous material is 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 for this invention ordinarily are refined to a Canadian Standard Freeness (CSF) at 0.3 percent consistency of from about 300 milliliters to about 700 milliliters, preferably from about 400 milliliters to about 600 milliliters.
• CSF Canadian Standard Freeness
• Synthetic fibers are similarly mechanically treated but unless specially treated do not fibrillate to give the same degree of dispersion as is obtained with cellulosic pulps so that the Canadian Standard Freeness test is not particularly adapted to such materials.
• the synthetic fibers generally have a fiber length up to about 3/8 inch, preferably from about 1/8 inch to about 1/4 inch.
• the consistency (percentage by weight of dry fibrous material) of the stock thus obtained ordinarily is from about 0.1 percent to about 6 percent, preferably from about 0.5 percent to about 3 percent.
• additional water is included to reduce the consistency of the resulting furnish to a value ordinarily within the range of from about 0.1 percent to about 6 percent, preferably from about 1 percent to about 5 percent.
• Part of the water of dilution advantageously is white water, or process water, recycled from later steps in the sheet-making process.
• some of the process water can be used in the step of refining the fiber.
• the filler, the dilution water and the latex generally prediluted to a lower solids content than at which it was manufactured, are added (usually but not necessarily in that order) to the fiber dispersion with agitation.
• At least some of the required colloidal destabilization can occur simultaneously with the mixing of the fiber, filler and latex either through interaction of the required components or through the concurrent addition of other optional wet-end additives such as those mentioned below.
• the mechanical shear caused by mixing and by transfer of the materials through the equipment used can cause, or assist in, the destabilization.
• the combination of the mixing and the destabilization steps produce a fibrous agglomerate in aqueous suspension, which at a concentration of 100 grams of solids in 13,500 milliliters of the aqueous suspension, should drain in a time of from about 4 seconds to about 120 seconds, especially from about 15 seconds to about 60 seconds and preferably from about 30 seconds to about 45 seconds in a 10-inch by 12-inch Williams Standard Sheet Mould, having a 2-inch outlet and a 30-inch water leg and fitted with a standard 100-mesh, stainless steel screen (wire size, 0.0045 inch) to provide in one pass at least 85 percent retention of solids which contain at least 60 percent by weight of filler.
• the drainage water is substantially clear.
• An effective and preferred method of carrying out (or completing the carrying out) of the destabilization is the mixing with the other components a flocculating agent, i.e., a water-dispersible or water-soluble, ionic compound having a charge opposite in sign (+ or -) to that of the ionic stabilization in a sufficient amount, such an amount generally being less than about 1 percent, based on the total dry weight of the components.
• a flocculant is added so that the destabilization can take place before the distributing and draining step.
• the flocculant is added at the stock chest or at such a point in the stock transfer portion of the apparatus that there is sufficient time for the desired action to take place yet not so much that the resulting flocculated stock is subjected to undue shear.
• the wet web obtained After distributing and draining the resulting aqueous dispersion, the wet web obtained thereby optionally is wet-pressed and then dried with equipment conventionally used in paper-making.
• the temperature of the process through the step of forming the wet web usually is in the range of from about 40°F (4.4°C) to about 130°F (54°C) although temperatures outside those ranges can be used provided that they are above the freezing point of the aqueous dispersion and are below the temperature at which the latex polymer being used would soften unduly. Sometimes temperatures above ambient conditions promote faster drainage.
• Such materials include antioxidants, various hydrocarbon and natural waxes, particularly in the form of anionic or cationic emulsions; cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose; water-soluble organic dyestuffs, water-insoluble but water-dispersible coloring pigments such as carbon black, vat colors and sulfur colors; starch, natural gums such as guar gum and locust bean gum, particularly their anionic and cationic derivatives; non-ionic acrlyamide polymers; strength improving resins such as melamine-formaldehyde resins, urea-formaldehyde resins and curing agents of various types such as the sulfur-containing vulcanizing agents and accessory compounds. Further quantities and/or kinds of anionic or cationic surfactants may also be added in small amounts at various points in the process if desired. Non-ionic surfactants should be antioxidants, various hydrocarbon and natural waxes, particularly in the form of anionic or cationic emulsions
• the densities of the products obtained from the above-described process cover a wide range, such as from about 30 pounds per cubic foot to about 150 pounds per cubic foot. Since the filler constitutes such a high proportion of the weight of the products, the identity of the filler selected for a particular product has considerable effect on the density and other properties of the product.
• the thickness of the sheet which is produced can vary from about 3 mils to about 125 mils, the preferred value depending somewhat upon the proposed use. However, the thickness generally is from about 15 mils to about 65 mils.
• the method of this invention results in production of water-laid, self-supporting sheets at high filler loading with a high proportion of the filler which is added being retained in the sheets.
• water-laid sheet refers to a sheet which is deposited from a dilute aqueous suspension, usually having a solids content of four percent or less. While the filler constitutes the major proportion of the sheet, the latex and fiber are also retained in the sheet in high proportions. Retention in the sheet of all of the solids used in the process generally is greater than 85 percent by weight and in the preferred embodiments is greater than 95 percent.
• the process and product of this invention has many advantages. In comparison with paper sheets of the prior art, there is less moisture in the sheet when it comes off the wet end of the machine. Hence, with the same bases weight of the sheet, less energy is required to dry the sheet and the machine can be run faster or a thicker sheet can be dried.
• the new process can be carried out using presently designed and available equipment of the kind commonly owned by paper manufacturers. Readily available raw materials are used. A large proportion of the raw materials is inexpensive filler and the total cost is low. The density can be altered simply by the choice of filler. The preferred embodiments also are asbestos-free.
• the indicated fiber if cellulosic is pulped to a Canadian Standard Freeness (CSF) of 500 milliliters and a consistency of about 1.2 percent by weight.
• CSF Canadian Standard Freeness
• the synthetic fibers are dispersed in water with a TAPPI disintegrator (600 counts) but a Canadian Standard Freeness measurement is not made. With a sufficient quantity of the resulting aqueous dispersion to provide 5 grams of the fiber, dry basis, is mixed an additional precalculated amount of water to give a final volume of 2000 milliliters.
• the freeness sample is returned to the furnish which is then diluted to 13,500 milliliters and a sheet is formed in a 10-inch by 12-inch Williams Standard Sheet Mould and the drainage time on a 100-mesh screen is recorded.
• the resulting wet sheet is couched from the wire in a press at approximately 10 pounds per square inch using two blotters to absorb water from the sheet.
• the sheets are stacked alternately with blotters and wet pressed at 500 pounds per square inch.
• the partially dried sheets are then weighed and dried on a sheet dryer at a platen temperature of 240° to 250°F (116° to 121°C), alternating sides of the sheet against the platen at.0.5 to 1-minute intervals.
• the resulting dried sheets are weighed to determine the total solids which are retained in the sheet. Since sufficient materials are used to make a 100-gram sheet on complete retention, the dry weight also represents the percent retention.
• Handsheets are prepared from the designated latex, unbleached southern pine kraft and the designated fillers using Flocculant A by the standard procedure described above except as indicated.
• the data for the preparation of the sheets are shown in Table I.
• the properties of the sheets are shown in Table II.
• Handsheets are prepared from the designated latex, the designated kind of fiber pulped to the designated Canadian Standard Freeness (CSF), the designated filler and the designated flocculant by the standard procedure described above except as indicated. Sheet preparation data are shown in Table III and the sheet properties in Table IV.
• Handsheets are prepared by the standard procedure described above wherein the fiber is Fiber D, and the filler, latex and flocculant are the kinds specified in Table V. Sheet properties are shown in Table VI.
• Handsheets are prepared by the standard procedure described above wherein the fiber is unbleached softwood kraft, the latex is Latex B, the filler is Filler A, and the flocculant is as specified. In addition of the flocculant, the indicated amount of alum was added first and stirred for one minute, then a sufficient amount of the other flocculant to complete flocculation was added. Data for preparation of the handsheets are shown in Table VII. 'Properties of the sheets are shown in Table VIII.
• Handsheets are prepared by the standard procedure described above wherein the fiber, latex, and flocculant are as shown and the filler is Filler A in the amount as shown. Data for the sheet preparation are shown in Table IX. Samples of the sheets are placed in a tropical chamber maintained at 100 percent relative humidity and 90°F (32.2°C) which has previously been inoculated with organisms including Aspergillus niger, Trichoderma viridie, Aureobasidium pullulans, Chaetomium globosum and unidentified species of Penicillium. At the end of 21 days and 49 days, the samples are checked for visible evidence of microbiological attack and room temperature tensile loss values are meaured on strips 3 inches long over a one-inch span of the samples.
• handsheets are prepared from 85 parts of asbestos (Johns Manville, Paperbestos No. 5) and 15 parts of Latex C (Comparative Example A-1) and 85 parts of asbestos and 15 parts of Latex B (Comparative Example A-2). Test data are shown in Table X.
• the visual rating is based on an arbitrary scale for visible evidence of microbiological attack as follows:
• Handsheets are prepared by the standard procedure described above except that different ratios of fiber, latex and filler are used.
• the fiber is unbleached softwood kraft
• the latex is Latex B
• the filler is Filler B
• the flocculant is Flocculant A. Data are shown in Table XI.
• a handsheet (Example 61) is prepared from unbleached softwood kraft, Latex F, Filler 0 and Flocculant A by the standard procedure described above.
• Another handsheet (Example 62) is prepared in the same manner except that 0.25 part of a cationic polyamide--epichlorohydrin resin (Kymene 557) is added as a 0.132 percent aqueous solution to the aqueous fiber dispersion before mixing with the filler and latex. Data are shown in Table XII.
• Handsheets are prepared from Latex N, Fiber R, and the designated filler using Flocculant E in the indicated amount according to the standard procedure except that a wet-strength additive, which is a cationic polyamide-epichlorohydrin resin having 12.8 percent nitrogen, is added after the filler in the amount shown in Table XIII, and 1 percent total solids basis, of an anionic emulsified hydrocarbon wax is added after the latex.
• a wet-strength additive which is a cationic polyamide-epichlorohydrin resin having 12.8 percent nitrogen
• handsheets are prepared from the designated latex, Fiber E and Filler Q using Flocculant E in the proportions shown in Table XIV for the latex, fiber and flocculant and the amount of filler is the difference between 100 percent and the total of latex and fiber, all on a dry solids basis. Also the amounts are chosen such as to provide handsheets theoretically weighing 75 grams rather than 100 grams and the dilution water of the furnish is reduced correspondingly. Data are shown in Table XIV.
• Latex R-1 With a portion of Latex R is blended 8 percent (based on the solids content of the latex) of carbon tetrachloride. The resulting product is centrifuged. The aqueous serum is removed and the remaining solids are washed with water. The resulting damp solids are redispersed in water by subjecting the solids and water to vigorous agitation for from 30 minutes to one hour. The resulting dispersion is Latex R-1 and has a pH of 3.8.
• the standard process for preparing handsheets is used with each of Latex R and Latex R-1 in a proportion of 15 percent of the respective latex, 15 percent of Fiber E and 75 percent of Filler K (solids basis, calculated on the weight of latex, fiber and filler) using 127 milliliters of a 0.1 percent aqueous solution of Flocculant E.
• Damp handsheets are formed with each of Latex R-1 (Example 71) and Latex R (Comparative Example 71-C) with a drainage time of 20 seconds and 29 seconds, respectively.
• Example 71 there is only a barely detectable amount of scum in preparation of the furnish with only slight sticking of the sheet to the wire when the damp handsheet is dried. During the addition of the flocculant, the progression of flocculation is easily observed. However, in comparative Example 71-C, a large amount of scum and froth appears in the preparation of the furnish. Such severe sticking of the dried handsheet to the wire and blotter occurs that a sheet cannot be separated from the wire.
• Latex R and Latex R-1 The bound charge on Latex R and Latex R-1 is the same because the procedure to prepare Latex R-1 from Latex R would not alter the existing bound charge (from carboxyl groups).
• the significant difference is the removal from Latex R of water soluble components, e.g., surfactants and acrylic acid polymers or copolymers of sufficiently low molecular weight and high enough carboxyl content to be water soluble.
• An aqueous dispersion of fiber is prepared at about 4 percent consistency from bleached southern pine kraft and water in a Black Clawson Hydrapulper.
• the crude dispersion is pumped to a refiner chest and refined to a Canadian Standard Freeness of 500 milliliters by recirculation through a Sprout-Waldron Twin-Flow Refiner.
• Highly filled sheets for Examples 72 and 73 are prepared from portions of the fiber dispersion, a latex and a filler as identified and in the proportions shown in Table XV by use of a 31-inch Fourdrinier paper machine having a phosphor bronze, long crimp wire, four flat suction boxes between the breast roll and a suction couch roll, a first wet press, a reverse press, a multi-section dryer with a size press between sections and a 7-roll calendar stack.
• the fiber dispersion, filler, water, and the latex diluted to 25 percent solids are added to a machine chest, in that order, with the amount of added water being calculated to provide 4 percent consistency.
• the resulting stock is transferred with the aid of a stock pump through a stock valve and then through a fan pump to the headbox.
• the flocculant shown in Table XV is added between the stock pump and the stock valve and some white water from the later stages of the process is returned to the system between the stock valve and the fan pump so that the consistency of the furnish in the headbox is as shown in Table XV.
• the furnish from the headbox is fed onto the wire moving at 20 feet per minute where white water drains to form a wet sheet from which additional water is removed by means of the four suction boxes before the sheet is removed from the wire at the suction couch roll. After the two press stages have reduced the water-content still further, the sheet is fed through the dryer and calendar stack. Data for the process and property data for the highly filled sheets thus formed are shown in Table XV.
• An aqueous dispersion of fiber is prepared at about 4 percent consistency from unbleached northern softwood kraft and water in a Black Clawson Hydrapulper.
• the crude dispersion is pumped to a refiner chest and refined to a Canadian Standard Freeness of 500 milliliters by recirculation through a Sprout-Waldron Twin-Flow Refiner.
• Highly filled sheets for Example 74 are prepared from the fiber dispersion, a latex, a filler as identified and a wet strength additive which is a cationic polyamide-epichlorohydrin resin having 12.8 percent nitrogen and a viscosity at 25°C between 40 and 65 centipoises, all in the proportions shown in Table XVI by use of a Fourdrinier Paper Machine having (a) a 36-inch wide plastic wire, (b) a headbox equipped with a manifold type inlet, a homogenizer roll and a Neilson slice, (c) a suction couch roll, (d) a straight-through plain press, (e) a plain reversing press, (f) 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 (g) a calendar stack consisting of 8 rolls with the intermediate rolls bored for steam.
• a Fourdrinier Paper Machine having (a) a 36-inch
• the fiber dispersion, filler, wet strength additive, water and the latex diluted to 25 percent solids are added to a machine chest, in that order, with the amount of added water being calculated to provide 4 percent consistency.
• the resulting stock is transferred with the aid of a stock pump through a stock valve and then through a fan pump to the headbox.
• the flocculant shown in Table XVI is added between the stock pump and the stock valve and some white water from the later stages of the process is returned to the system between the stock valve and the fan pump so that the consistency of the furnish in the headbox is as shown in Table XVI.
• the furnish from the headbox is fed onto the wire moving at 40 feet per minute where white water drains to form a wet sheet from which additional water is removed by means of suction boxes before the sheet is removed from the wire at the suction couch roll.
• the sheet is fed through the dryer and calendar stack. Data for the process and property data for the highly filled sheets thus formed are shown in Table XVI.
• the value, in milliliters, is determined according to TAPPI Standard T 227-M-58 on a sample containing 3 grams of solids diluted with water to 1000 milliliters.
• test is carried out according to TAPPI method T414-ts-65. Results are shown as an average of at least 3 samples.
• the L.O.I. is determined according to test method ASTM D 2863-74.
• the TAPPI test method D 403-os-76 is followed except the test is applied to thicker sheets.
• the results shown are an average of 4 or 5 samples.
• the materials for the handsheets are added in amounts sufficient to provide sheets weighing 100 grams.
• the dry weight of the product also represents the percent retention of solids in the sheet.
• the percent retention relates to the proportion of filler retained in the sheet.
• Combustion of test samples is carried out under conditions such as to retain the residue of the filler (calculated as percent ash) but to remove the other components.
• the percent ash is multiplied by an appropriate factor for changes in the filler caused by combustion (e.g., Mg(OH) 2 ⁇ MgO) to determine the percent filler in the sheet. From the percent filler found in the sheet and the percent filler added (solids basis), the percent retained in the sheet is calculated as an average of three samples.
• Taber Stiffness (g-cm) is determined according to TAPPI standard method T 489-os-76 except that test results from three samples are averaged unless otherwise stated. The value obtained is corrected to a value for 30 mils thickness by multiplying by the factor:
• TAPPI method is sometimes referred to herein as "Taber Stiffness, Reg.”
• the DOP stiffness (g-cm) is determined in the same manner as the Taber Stiffness except that the sample is soaked in dioctyl phthalate for 18-24 hours before testing and the reported value is the average of 2 samples.
• the water stiffness is determined in the same manner as the Taber Stiffness except that the sample is soaked in water for 18-24 hours before testing and the reported value is the average of two samples.
• Sheets are cut into 1-inch by 8-inch strips and the minimum thickness over the test area is determined.
• the strip being tested is placed in an instron test machine having a 6-inch span. While the Instron is operated at a head speed of one inch per minute, the elongation and pounds at break are recorded.
• the pounds per square inch (psi) at break are calculated by dividing the tensile at break by the thickness of the sample. Results are reported as an average of 3 samples.
• the hot tensile is tested in the same manner as room temperature tensile except that just before the test, the test specimen is heated at a temperature of 350°F (177°C) for one minute while clamped in the jaws of the test machine.
• the DOP tensile is tested in the same manner as the room temperature tensile except that the test sample is soaked in dioctyl phthalate for 24 hours before testing.
• the water tensile is determined in the same manner as the DOP tensile, except the soaking is in water.
• a suitable specimen (2 inches by 4 inches) is soaked for 15 seconds in toluene, the weight pickup is recorded and the pickup in percent by weight is calculated.
• the kerosene pickup is measured in the same manner as the toluene pickup except the soaking is in kerosene.
• the water pickup is determined in the same manner as the toluene pickup except that the soaking is in water for 24 hours.
• the water swell is determined in the same kind of specimen as used for the water pickup and is calculated on the increase in length of the specimen resulting from soaking in water for 24 hours.
• the bound charge per gram of polymer in a latex is measured by conductometric titration after the water-soluble ionic materials have been removed. If sufficient bound charge is present, the latex can be centrifuged, often after adding, for example, 3 percent (based on the latex solids) of carbon tetrachloride, the serum phase is separated, the remaining solids are washed and then redispersed by vigorous agitation in water. The conductometric titrations are made on the redispersed solids. Ion exchange methods also may be used to remove the ionic water--soluble materials from latexes having sufficient bound charge to remain stable until the conductometric titration is completed. For latexes having insufficient bound charge to remain stable, small amounts of non-ionic surfactants are added before the ion exchange procedure.

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• 1978
  • 1978-12-20 NO NO784302A patent/NO154350C/no unknown
  • 1978-12-20 CA CA318,286A patent/CA1112006A/en not_active Expired
  • 1978-12-21 FI FI783958A patent/FI64675C/fi not_active IP Right Cessation
  • 1978-12-21 DE DE7878101807T patent/DE2862076D1/de not_active Expired
  • 1978-12-21 EP EP78101807A patent/EP0003481B1/de not_active Expired
  • 1978-12-21 JP JP15842278A patent/JPS54106605A/ja active Granted
  • 1978-12-21 BE BE192481A patent/BE872966A/xx not_active IP Right Cessation
  • 1978-12-21 CH CH1303578A patent/CH640026A5/de not_active IP Right Cessation
  • 1978-12-21 IT IT52400/78A patent/IT1110869B/it active
  • 1978-12-22 DK DK580378A patent/DK153575C/da active
  • 1978-12-28 FR FR7836629A patent/FR2416291A1/fr active Granted
  • 1978-12-29 AU AU42981/78A patent/AU524468B2/en not_active Expired
• 1979
  • 1979-01-04 NZ NZ189303A patent/NZ189303A/xx unknown
  • 1979-01-05 BR BR7900060A patent/BR7900060A/pt unknown
  • 1979-01-11 ES ES476778A patent/ES476778A1/es not_active Expired
• 1981
  • 1981-06-11 JP JP56090168A patent/JPS57112500A/ja active Pending

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