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
  • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
  • D21H27/002—Tissue paper; Absorbent paper
  • D21H27/004—Tissue paper; Absorbent paper characterised by specific parameters
  • D21H27/005—Tissue paper; Absorbent paper characterised by specific parameters relating to physical or mechanical properties, e.g. tensile strength, stretch, softness
• • 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
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
  • D21H21/22—Agents rendering paper porous, absorbent or bulky
• • 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
  • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
  • D21H27/30—Multi-ply
• • 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
  • D21H17/03—Non-macromolecular organic compounds
  • D21H17/05—Non-macromolecular organic compounds containing elements other than carbon and hydrogen only
  • D21H17/07—Nitrogen-containing compounds
• • 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
  • D21H19/00—Coated paper; Coating material
  • D21H19/10—Coatings without pigments
  • D21H19/12—Coatings without pigments applied as a solution using water as the only solvent, e.g. in the presence of acid or alkaline compounds
• • 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
  • D21H19/00—Coated paper; Coating material
  • D21H19/10—Coatings without pigments
  • D21H19/14—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12
  • D21H19/24—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12 comprising macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H19/32—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12 comprising macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds obtained by reactions forming a linkage containing silicon in the main chain of the macromolecule

Definitions

• This invention relates, in general, to tissue paper products. More specifically, it relates to tissue paper products containing chemical softening agent.
• Sanitary paper tissue products are widely used. Such items are commercially offered in formats tailored for a variety of uses such as facial tissues, toilet tissues and absorbent towels.
• tissue and toweling products are offered to aid in the task of removing from the skin and retaining the before mentioned discharges for disposal in a sanitary fashion.
• the use of these products does not approach the level of cleanliness that can be achieved by the more thorough cleansing methods, and producers of tissue and toweling products are constantly striving to make their products compete more favorably with thorough cleansing methods.
• the term “chemical softening agent” refers to any chemical ingredient which improves the tactile sensation perceived by the consumer who holds a particular paper product and rubs it across the skin. Although somewhat desirable for towel products, softness is a particularly important property for facial and toilet tissues. Such tactile perceivable softness can be characterized by, but is not limited to, friction, flexibility, and smoothness, as well as subjective descriptors, such as lubricious, velvet, silk or flannel, which imparts a lubricious feel to tissue.
• basic waxes such as paraffin and beeswax and oils such as mineral oil and silicone oil as well as petrolatum and more complex lubricants and emollients such as quaternary ammonium compounds with long alkyl chains, functional silicones, fatty acids, fatty alcohols and fatty esters.
• Strength is the ability of the product, and its constituent webs, to maintain physical integrity and to resist tearing, bursting, and shredding under use conditions. Achieving a high softening potential without degrading strength has long been an object of workers in the field of the present invention.
• the present invention provides for a tissue paper product having at least one ply wherein only one outer surface of the tissue paper product has a chemical softening agent applied and substantially affixed thereto.
• the chemical softening agent provides the tissue paper product with a raw dispensing dust value.
• the dust value is at least about 13.6 percent less than the raw dispensing dust value of a tissue paper product not having the chemical softening agent applied and substantially affixed thereto.
• the present invention also provides for a through-air dried tissue paper product having at least one ply wherein only one outer surface of the tissue paper product has a chemical softening agent applied and substantially affixed thereto.
• the chemical softening agent provides the tissue paper product with a raw dispensing dust value of less than out 6485 particles.
• water soluble refers to materials that are soluble in water to at least 3%, by weight, at 25° C.
• tissue paper web, paper web, web, paper sheet and paper product are all used interchangeably to refer to sheets of paper made by a process comprising the steps of forming an aqueous papermaking furnish, depositing this furnish on a foraminous surface, such as a Fourdrinier wire, and removing the water from the furnish as by gravity or vacuum-assisted drainage, forming an embryonic web, transferring the embryonic web from the forming surface to a transfer surface traveling at a lower speed than the forming surface. The web is then transferred to a fabric upon which it is through air dried to a final dryness after which it is wound upon a reel.
• a foraminous surface such as a Fourdrinier wire
• multi-layered tissue paper web, multi-layered paper web, multi-layered web, multi-layered paper sheet and multi-layered paper product are all used interchangeably in the art to refer to sheets of paper prepared from two or more layers of aqueous paper making furnish which are preferably comprised of different fiber types, the fibers typically being relatively long softwood and relatively short hardwood fibers as used in tissue paper making.
• the layers are preferably formed from the deposition of separate streams of dilute fiber slurries upon one or more endless foraminous surfaces. If the individual layers are initially formed on separate foraminous surfaces, the layers can be subsequently combined when wet to form a multi-layered tissue paper web.
• single-ply tissue product means that it is comprised of one ply of uncreped tissue; the ply can be substantially homogeneous in nature or it can be a multi-layered tissue paper web.
• multi-ply tissue product means that it is comprised of more than one ply of uncreped tissue.
• the plies of a multi-ply tissue product can be substantially homogeneous in nature or they can be multi-layered tissue paper webs.
• the term “substantively affixed chemical softening agent” is defined as a chemical agent which imparts lubricity or emolliency to tissue paper products and also possesses permanence with regard to maintaining the fidelity of its deposits without substantial migration when exposed to the environmental conditions to which products of this type are ordinarily exposed during their typical life cycle.
• Waxes and oils for example are capable of imparting lubricity or emolliency to tissue paper, but they suffer from a tendency to migrate because they have little affinity for the cellulose pulps which comprise the tissue papers of the present invention.
• the substantively affixed chemical softeners of the present invention are believed to interact with the cellulose by covalent, ionic, or hydrogen bonding any of which are sufficiently potent to stem migration under normal environmental conditions.
• the substantively affixed chemical softening agents comprise quaternary ammonium compounds.
• Preferred quaternary compounds have the formula:
• each R 1 is methyl and X ⁇ is chloride or methyl sulfate.
• each R 2 is C 16 -C 18 alkyl or alkenyl, most preferably each R 2 is straight-chain C 18 alkyl or alkenyl.
• the R 2 substituent can be derived from vegetable oil sources.
• Such structures include the well-known dialkyldimethylammonium salts (e.g. ditallowdimethylammonium chloride, ditallowdimethylammonium methyl sulfate, di(hydrogenated tallow)dimethyl ammonium chloride, etc.), in which R 1 are methyl groups, R 2 are tallow groups of varying levels of saturation, and X ⁇ is chloride or methyl sulfate.
• dialkyldimethylammonium salts e.g. ditallowdimethylammonium chloride, ditallowdimethylammonium methyl sulfate, di(hydrogenated tallow)dimethyl ammonium chloride, etc.
• tallow is a naturally occurring material having a variable composition.
• Table 6.13 in the above-identified reference edited by Swern indicates that typically 78% or more of the fatty acids of tallow contain 16 or 18 carbon atoms. Typically, half of the fatty acids present in tallow are unsaturated, primarily in the form of oleic acid. Synthetic as well as natural “tallows” fall within the scope of the present invention. It is also known that depending upon the product characteristic requirements the saturation level of the ditallow can be tailored from non hydrogenated (soft) to touch, partially or completely hydrogenated (hard). All of above-described levels of saturations are expressly meant to be included within the scope of the present invention.
• each R 1 substituent is preferably a C 1 -C 3 , alkyl group, with methyl being most preferred.
• each R 3 is C 13 -C 17 alkyl and/or alkenyl, more preferably R 3 is straight chain C 15 -C 17 alkyl and/or alkenyl, C 15 -C 17 alkyl, most preferably each R 3 is straight-chain C 17 alkyl.
• the R 3 substituent can be derived from vegetable oil sources.
• X ⁇ can be any softener-compatible anion, for example, acetate, chloride, bromide, methylsulfate, formate, sulfate, nitrate and the like.
• X ⁇ is chloride or methyl sulfate.
• ester-functional quaternary ammonium compounds having the structures detailed above and suitable for use in the present invention may include the diester dialkyl dimethyl ammonium salts such as diester ditallow dimethyl ammonium chloride, monoester ditallow dimethyl ammonium chloride, diester ditallow dimethyl ammonium methyl sulfate, diester di(hydrogenated)tallow dimethyl ammonium methyl sulfate, diester di(hydrogenated)tallow dimethyl ammonium chloride, and mixtures thereof. Diester ditallow dimethyl ammonium chloride and diester di(hydrogenated)tallow dimethyl ammonium chloride are particularly preferred. These particular materials are available commercially from Witco Chemical Company Inc. of Dublin, Ohio under the tradename “ADOGEN SDMC”.
• tallow half of the fatty acids present in tallow are unsaturated, primarily in the form of oleic acid. Synthetic as well as natural “tallows” fall within the scope of the present invention. It is also known that depending upon the product characteristic requirements, the saturation level of the ditallow can be tailored from non hydrogenated (soft) to touch, partially or completely hydrogenated (hard). All of above-described levels of saturations are expressly meant to be included within the scope of the present invention.
• substituents R 1 , R 2 and R 3 may optionally be substituted with various groups such as alkoxyl, hydroxyl, or can be branched.
• each R 1 is methyl or hydroxyethyl.
• each R 2 is C 12 -C 18 alkyl and/or alkenyl, most preferably each R 2 is straight-chain C 16 -C 18 alkyl and/or alkenyl, most preferably each R 2 is straight-chain C 18 alkyl or alkenyl.
• R 3 is C13-C17 alkyl and/or alkenyl, most preferably R 3 is straight chain C 15 -C 17 alkyl and/or alkenyl.
• X ⁇ is chloride or methyl sulfate.
• ester-functional quaternary ammonium compounds can optionally contain up to about 10% of the mono(long chain alkyl) derivatives, e.g., (R 2 ) 2 —N+—((CH 2 ) 2 OH) ((CH 2 ) 2 OC(O)R 3 ) X ⁇ as minor ingredients. These minor ingredients can act as emulsifiers and can be useful in the present invention.
• ester-functional quaternary ammonium compounds can also be used, and are meant to fall within the scope of the present invention. These compounds have the formula:
• each R 1 is a C 1 -C 6 alkyl or hydroxyalkyl group
• R 3 is C 11 -C 21 hydrocarbyl group
• n is 2 to 4
• X ⁇ is a suitable anion, such as a halide (e.g., chloride or bromide) or methyl sulfate.
• each R 3 is C 13 -C 17 alkyl and/or alkenyl, most preferably each R 3 is straight-chain C 15 -C 17 alkyl and/or alkenyl, and R 1 is a methyl.
• ester moiety(ies) of the quaternary compounds provides a measure of biodegradability. It is believed the ester-functional quaternary ammonium compounds used herein biodegrade more rapidly than do conventional dialkyl dimethyl ammonium chemical softeners.
• the plasticizer can be added during the quaternizing step in the manufacture of the quaternary ammonium ingredient or it can be added subsequent to the quaternization but prior to the application as a chemical softening agent.
• the plasticizer is characterized by being substantially inert during the chemical synthesis, but acts as a viscosity reducer to aid in the synthesis and subsequent handling, i.e. application of the quaternary ammonium compound to the tissue paper product.
• Preferred pasticizers are comprised of a combination of a non-volatile polyhydroxy compound and a fatty acid.
• Preferred polyhydroxy compounds include glycerol and polyethylene glycols having a molecular weight of from about 200 to about 2000, with polyethylene glycol having a molecular weight of from about 200 to about 600 being particularly preferred.
• Preferred fatty acids comprise C 6 -C 23 linear or branched and saturated or unsaturated analogs with isostearic acid being the most preferred.
• preferred substantively affixed chemical softening agents comprise well-known organo-reactive polydimethyl siloxane ingredients, including the most preferred—amino functional polydimethyl siloxane.
• a most preferred form of the substantively affixed softening agent is to combine the organo-reactive silicone with a suitable quaternary ammonium compound.
• the organo-reactive silicone is preferred to be an amino polydimethyl siloxane and is used at an amount ranging from 0 up to about 50% of the composition by weight, with a preferred usage being in the range of about 5% to about 15% by weight based on the weight of the polysiloxane relative to the total substantively affixed softening agent.
• the soft tissue paper of the present invention preferably has a basis weight ranging from between about 5 g/m 2 and about 120 g/m 2 , more preferably between about 10 g/m 2 and about 55 g/m 2 , and even more preferably between about 10 g/m 2 and about 30 g/m 2 .
• the soft tissue paper of the present invention preferably has a density ranging from between about 0.01 g/m 3 and about 0.19 g/cm 3 , more preferably between about 0.03 g/m 3 and about 0.6 g/cm 3 , and even more preferably between about 0.1 g/cm 3 and 0.2 g/cm 3 .
• the soft tissue paper of the present invention further comprises papermaking fibers of both hardwood and softwood types wherein at least about 50% of the papermaking fibers are hardwood and at least about 10% are softwood.
• the hardwood and softwood fibers are most preferably isolated by relegating each to separate layers wherein the tissue comprises an inner layer and at least one outer layer.
• the tissue paper product of the present invention is preferably creped, i.e., produced on a papermaking machine culminating with a Yankee dryer to which a partially dried papermaking web is adhered and upon which it is dried and from which it is removed by the action of a flexible creping blade.
• Creping is a means of mechanically compacting paper in the machine direction. The result is an increase in basis weight (mass per unit area) as well as dramatic changes in many physical properties, particularly when measured in the machine direction. Creping is generally accomplished with a flexible blade, a so-called doctor blade, against a Yankee dryer in an on machine operation.
• a Yankee dryer is a large diameter, generally 8-20 foot drum which is designed to be pressurized with steam to provide a hot surface for completing the drying of papermaking webs at the end of the papermaking process.
• the paper web which is first formed on a foraminous forming carrier, such as a Fourdrinier wire, where it is freed of the copious water needed to disperse the fibrous slurry is generally transferred to a felt or fabric in a so-called press section where de-watering is continued either by mechanically compacting the paper or by some other de-watering method such as through-drying with hot air, before finally being transferred in the semi-dry condition to the surface of the Yankee for the drying to be completed.
• a foraminous forming carrier such as a Fourdrinier wire
• uncreped tissue paper is also a satisfactory substitute and the practice of the present invention using uncreped tissue paper is specifically incorporated within the scope of the present invention.
• Uncreped tissue paper a term as used herein, refers to tissue paper which is non-compressively dried, most preferably by throughdrying. Resultant through air dried webs are pattern densified such that zones of relatively high density are dispersed within a high bulk field, including pattern densified tissue wherein zones of relatively high density are continuous and the high bulk field is discrete.
• an embryonic web is transferred from the foraminous forming carrier upon which it is laid, to a slower moving, high fiber support transfer fabric carrier. The web is then transferred to a drying fabric upon which it is dried to a final dryness.
• Such webs can offer some advantages in surface smoothness compared to creped paper webs.
• Tissue paper webs are generally comprised essentially of papermaking fibers. Small amounts of chemical functional agents such as wet strength or dry strength binders, retention aids, surfactants, size, chemical softeners, crepe facilitating compositions are frequently included but these are typically only used in minor amounts.
• the papermaking fibers most frequently used in tissue papers are virgin chemical wood pulps. Additionally, filler materials may also be incorporated into the tissue papers of the present invention.
• Embodiments of the present invention wherein the substantively affixed softening agent comprises a quaternary ammonium compound further comprise from about 1% to about 50% of a polyhydroxy compound and from about 0.1% to about 10% of a fatty acid, each as a percentage of the weight of the quaternary ammonium compound.
• Polyhydroxy compounds useful in this embodiment of the present invention include polyethylene glycol, polypropylene glycol and mixtures thereof.
• Fatty acids useful in this embodiment of the present invention comprises C 6 -C 23 linear, branched, saturated, or unsaturated analogs.
• the most preferred form of such a fatty acid is isostearic acid.
• One particularly preferred chemical softening agent contains from about 0.1% to about 70% of a polysiloxane compound.
• Polysiloxanes which are applicable to chemical softening compositions of the present invention include polymeric, oligomeric, copolymeric, and other multiple monomeric siloxane materials.
• polysiloxane shall include all of such polymeric, oligomeric, copolymeric, and other multiple-monomeric materials. Additionally, the polysiloxane can be straight chained, branched chain, or have a cyclic structure.
• Preferred polysiloxane materials include those having monomeric siloxane units of the following structure:
• R 1 and R 1 for each siloxane monomeric unit can independently be any alkyl, aryl, alkenyl, alkaryl, aralkyl, cycloalkyl, halogenated hydrocarbon, or other radical. Any of such radicals can be substituted or unsubstituted.
• R 1 and R 2 radicals of any particular monomeric unit may differ from the corresponding functionalities of the next adjoining monomeric unit. Additionally, the radicals can be either a straight chain, a branched chain, or have a cyclic structure.
• the radicals R 1 and R 2 can, additionally and independently be other silicone functionalities such as, but not limited to siloxanes, polysiloxanes, and polysilanes.
• the radicals R 1 and R 2 can also contain any of a variety of organic functionalities including, for example, alcohol, carboxylic acid, and amine functionalities.
• Reactive, organo-functional silicones, especially amino-functional silicones are preferred for the present invention.
• Preferred polysiloxanes include straight chain organopolysiloxane materials of the following general formula:
• each R 1 -R 9 radical can independently be any C 1 -C 10 unsubstituted alkyl or aryl radical, and R 10 of any substituted C 1 -C 10 alkyl or aryl radical.
• each R 1 -R 9 radical is independently any C 1 -C 4 unsubstituted alkyl group those skilled in the art will recognize that technically there is no difference whether, for example, R 9 or R 10 is the substituted radical.
• the mole ratio of b to (a+b) is between 0 and about 20%, more preferably between 0 and about 10%, and most preferably between about 1% and about 5%.
• R 1 -R 9 are methyl groups and R 10 is a substituted or unsubstituted alkyl, aryl, or alkenyl group.
• Such material shall be generally described herein as polydimethylsiloxane which has a particular functionality as may be appropriate in that particular case.
• Exemplary polydimethylsiloxane include, for example, polydimethylsiloxane having an alkyl hydrocarbon R 10 radical and polydimethylsiloxane having one or more amino, carboxyl, hydroxyl, ether, polyether, aldehyde, ketone, amide, ester, thiol, and/or other functionalities including alkyl and alkenyl analogs of such functionalities.
• an amino functional alkyl group as R 10 could be an amino functional or an aminoalkyl-functional polydimethylsiloxane.
• the exemplary listing of these polydimethylsiloxanes is not meant to thereby exclude others not specifically listed.
• Viscosity of polysiloxanes useful for this invention may vary as widely as the viscosity of polysiloxanes in general vary, so long as the polysiloxane can be rendered into a form which can be applied to the tissue paper product herein. This includes, but is not limited to, viscosity as low as about 25 centistokes to about 20,000,000 centistokes or even higher. High viscosity polysiloxanes which themselves are resistant to flowing can be effectively deposited by emulsifying with a surfactant or dissolution into a vehicle, such as hexane, listed for exemplary purposes only.
• the tactile benefit efficacy is related to average molecular weight and that viscosity is also related to average molecular weight. Accordingly, due to the difficulty of measuring molecular weight directly, viscosity is used herein as the apparent operative parameter with respect to imparting softness to tissue paper.
• references disclosing polysiloxanes include U.S. Pat. Nos. 2,826,551; 3,964,500; 4,364,837; 5,059,282; 5,529,665; 5,552,020; and British Patent 849,433.
• wood pulp in all its varieties will normally comprise the tissue papers with utility in this invention.
• other cellulose fibrous pulps such as cotton linters, bagasse, rayon, etc.
• Wood pulps useful herein include chemical pulps such as, sulfite and sulfate (sometimes called Kraft) pulps as well as mechanical pulps including for example, ground wood, ThermoMechanical Pulp (TMP) and Chemi-ThermoMechanical Pulp (CTMP). Pulps derived from both deciduous and coniferous trees can be used.
• Hardwood pulps and softwood pulps may be employed as papermaking fibers for the tissue paper of the present invention.
• the term “hardwood pulps” as used herein refers to fibrous pulp derived from the woody substance of deciduous trees (angiosperms), whereas “softwood pulps” are fibrous pulps derived from the woody substance of coniferous trees (gymnosperms).
• Blends of hardwood Kraft pulps, especially eucalyptus, and northern softwood Kraft (NSK) pulps are particularly suitable for making the tissue webs of the present invention.
• a preferred embodiment of the present invention comprises the use of layered tissue webs wherein, most preferably, hardwood pulps such as eucalyptus are used for outer layer(s) and wherein northern softwood Kraft pulps are used for the inner layer(s). Also applicable to the present invention are fibers derived from recycled paper, which may contain any or all of the above categories of fibers.
• the furnish containing the papermaking fibers which will be contacted by the particulate filler is predominantly of the hardwood type, preferably of content of at least about 80% hardwood.
• aqueous papermaking furnish or the embryonic web can be added to the aqueous papermaking furnish or the embryonic web to impart other characteristics to the product or improve the papermaking process so long as they are compatible with the chemistry of the substantively affixed softening agent and do not significantly and adversely affect the softness, strength, or low dusting character of the present invention.
• the following materials are expressly included, but their inclusion is not offered to be all-inclusive.
• Other materials can be included as well so long as they do not interfere or counteract the advantages of the present invention.
• a cationic charge biasing species it is common to add a cationic charge biasing species to the papermaking process to control the zeta potential of the aqueous papermaking furnish as it is delivered to the papermaking process.
• a cationic charge biasing species is alum. More recently in the art, charge biasing is done by use of relatively low molecular weight cationic synthetic polymers preferably having a molecular weight of no more than about 500,000 and more preferably no more than about 200,000, or even about 100,000. The charge densities of such low molecular weight cationic synthetic polymers are relatively high.
• charge densities range from about 4 to about 8 equivalents of cationic nitrogen per kilogram of polymer.
• One example material is Cypro 514.®., a product of Cytec, Inc. of Stamford, Conn. The use of such materials is expressly allowed within the practice of the present invention.
• the group of chemicals including polyamide-epichlorohydrin, polyacrylamides, styrene-butadiene latices; insolubilized polyvinyl alcohol; urea-formaldehyde; polyethyleneimine; chitosan polymers and mixtures thereof can be added to the papermaking furnish or to the embryonic web.
• Polyamide-epichlorohydrin resins are cationic wet strength resins which have been found to be of particular utility. Suitable types of such resins are described in U.S. Pat. Nos. 3,700,623 and 3,772,076.
• One commercial source of useful polyamide-epichlorohydrin resins is Hercules, Inc. of Wilmington, Del., which markets such resin under the mark Kymene 557H.®.).
• the binder materials can be chosen from the group consisting of dialdehyde starch or other resins with aldehyde functionality such as Co-Bond 1000.® offered by National Starch and Chemical Company, Parez 750.® offered by Cytec of Stamford, Conn. and the resin described in U.S. Pat. No. 4,981,557 issued on Jan. 1, 1991, to Bjorkquist and incorporated herein by reference.
• surfactants may be used to treat the tissue paper webs of the present invention.
• the level of surfactant if used, is preferably from about 0.01% to about 2.0% by weight, based on the dry fiber weight of the tissue paper.
• the surfactants preferably have alkyl chains with eight or more carbon atoms.
• Exemplary anionic surfactants are linear alkyl sulfonates, and alkylbenzene sulfonates.
• Exemplary nonionic surfactants are alkylglycosides including alkylglycoside esters such as Crodesta SL-40.® which is available from Croda, Inc. (New York, N.Y.); alkylglycoside ethers as described in U.S. Pat.
• the present invention is further applicable to the production of multi-layered tissue paper webs.
• Multilayered tissue structures and methods of forming multilayered tissue structures are described in U.S. Pat. Nos. 3,994,771; 4,300,981; 4,166,001; and European Patent Publication No. 0 613 979 A1.
• the layers preferably comprise different fiber types, the fibers typically being relatively long softwood and relatively short hardwood fibers as used in multi-layered tissue paper making.
• Multi-layered tissue paper webs resultant from the present invention comprise at least two superposed layers, an inner layer and at least one outer layer contiguous with the inner layer.
• the multi-layered tissue papers comprise three superposed layers, an inner or center layer, and two outer layers, with the inner layer located between the two outer layers.
• the two outer layers preferably comprise a primary filamentary constituent of relatively short paper making fibers having an average fiber length between about 0.5 and about 1.5 mm, preferably less than about 1.0 mm. These short paper making fibers typically comprise hardwood fibers, preferably hardwood Kraft fibers, and most preferably derived from eucalyptus.
• the inner layer preferably comprises a primary filamentary constituent of relatively long paper making fiber having an average fiber length of least about 2.0 mm. These long paper making fibers are typically softwood fibers, preferably, northern softwood Kraft fibers.
• the majority of the particulate filler of the present invention is contained in at least one of the outer layers of the multi-layered tissue paper web of the present invention. More preferably, the majority of the particulate filler of the present invention is contained in both of the outer layers.
• the tissue paper products made from single-layered or multi-layered uncreped tissue paper webs can be single-ply tissue products or multi-ply tissue products.
• dust is used herein to refer to the tendency of a tissue paper web to release fibers or particulate fillers as measured in a controlled abrasion test, described infra. Dust can be related to strength since the tendency to release fibers or particles is directly related to the degree to which such fibers or particles are anchored into the structure. As the overall level of anchoring is increased, the strength will be increased. However, it is possible to have a level of strength which is regarded as acceptable but have an unacceptable level of dust. This is because dust can be localized. For example, the surface of a tissue paper web can be prone to dust, while the degree of bonding beneath the surface can be sufficient to raise the overall level of strength to quite acceptable levels.
• the strength can be derived from a skeleton of relatively long papermaking fibers, while fiber fines or the particulate filler can be insufficiently bound within the structure.
• the tissue paper webs of the present invention are relatively low in lint. Levels of lint below about 12 are preferable, and below about 10 are more preferable.
• the multi-layered tissue paper webs of to the present invention can be used in any application where soft, absorbent multi-layered tissue paper webs are required. Particularly advantageous uses of the multi-layered tissue paper web of this invention are in toilet tissue and facial tissue products. Both single-ply and multi-ply tissue paper products can be produced from the webs of the present invention.
• chemical softening agents may be applied to a paper web by any application method known in the industry such as, for example, spraying, printing, extrusion, brushing, by means of permeable or impermeable rolls and/or pads.
• the claimed softening agent may be applied to a paper web with a slot die.
• the chemical softening agent may be extruded onto the surface of a paper web via a heated slot die.
• the slot die may be any suitable slot die or other means for applying chemical softening agent to the paper web.
• the slot die or other glue application means may be supplied by any suitable apparatus.
• the slot die may be supplied by a heated hopper or drum and a variable speed gear pump through a heated hose.
• the chemical softening agent is preferably extruded onto the surface of the paper web at a temperature that permits the chemical softening agent to bond to the paper web.
• the chemical softening agent can be at least partially transferred to rolls in a metering stack (if used) and then to the paper web.
• the chemical softening agent may be applied to a paper web by an apparatus comprising a fluid transfer component.
• the fluid transfer component preferably comprises a first surface and a second surface.
• the fluid transfer component further preferably comprises pores connecting the first surface and the second surface. The pores are disposed upon the fluid transfer component in a non-random pre-selected pattern.
• a fluid supply is operably connected to the fluid transfer component such that a fluid (such as the chemical softening agent) may contact the first surface of the fluid transfer component.
• the apparatus further comprises a fluid motivating component.
• the fluid motivating component provides an impetus for the fluid to move from the first surface to the second surface via the pores.
• the apparatus further comprises a fluid receiving component comprising a paper web.
• the paper web comprises a fluid receiving (or outer) surface.
• the fluid receiving surface may contact droplets of fluid formed upon the second surface. Fluid may pass through pores from the first surface to the second surface and may transfer to the fluid receiving surface.
• the fluid transfer component may comprise a hollow cylindrical shell.
• the cylindrical shell may be sufficiently structural to function without additional internal bracing.
• the cylindrical shell may comprise a thin outer shell and structural internal bracing to support the cylindrical shell.
• the cylindrical shell may comprise a single layer of material or may comprise a laminate.
• the laminate may comprise layers of a similar material or may comprise layers dissimilar in material and structure.
• the cylindrical shell comprises a stainless steel shell having a wall thickness of about 0.125 inches (3 mm).
• the fluid transfer component may comprise a flat plate.
• the fluid transfer component may comprise a regular or irregular polygonal prism.
• the fluid application width of the apparatus may be adjusted by providing a single fluid transfer component of appropriate width. Multiple individual fluid application components may be combined in a series to achieve the desired width.
• a plurality of stainless steel cylinders each having a shell thickness of about 0.125 inches (3 mm) and a width of about 6 inches (about 15 cm) may be coupled end to end with an appropriate seal—such as an o-ring seal between each pair of cylinders.
• an appropriate seal such as an o-ring seal between each pair of cylinders.
• the number of shells combined may be increased until the desired application width is achieved.
• the fluid transfer component preferably further comprises pores connecting the first surface 110 and the second surface. Connecting the surfaces refers to the pores each providing a pathway for the transport of a fluid from the first surface 110 to the second surface.
• the pores may be formed by the use of electron beam drilling as is known in the art. Electron beam drilling comprises a process whereby high energy electrons impinge upon a surface resulting in the formation of holes through the material.
• the pores may be formed using a laser.
• the pores may be formed by using a drill bit.
• the pores may be formed using electrical discharge machining as if known in the art.
• an array of pores may be disposed to provide a uniform distribution of fluid droplets to maximize the ratio of fluid surface area to applied fluid volume. In one embodiment, this may be used to apply a chemical softening agent in a pattern of dots to maximize the potential for adhesion between two surfaces for any volume of applied chemical softening agent.
• the pattern of pores upon the second surface may comprise an array of pores having a substantially similar diameter or may comprise a pattern of pores having distinctly different pore diameters.
• the array of pores may comprise a first set of pores having a first diameter and arranged in a first pattern.
• the array further comprises a second set of pores having a second diameter and arranged in a second pattern.
• the first and second patterns may be arranged to interact each with the other.
• the chemical softening agent may be sprayed directly onto the surface of a paper web using equipment suitable for such a purpose and as well known to those of skill in the art.
• the density of multi-layered tissue paper is the average density calculated as the basis weight of that paper divided by the caliper, with the appropriate unit conversions incorporated therein.
• Caliper of the multi-layered tissue paper is the thickness of the paper when subjected to a compressive load of 95 g/in 2 (15.5 g/cm 2 ).
• Dust is measured using a particle counter commercially available (Sympatec QICPIC, Sympatec GmbH, Am Pulverhaus 1, 38678 Clausthal-Zellerfeld, Germany).
• the instrument is used according to the manufacturer's recommendation and a frame rate of 400 frames/sec is selected.
• the particle size range is set to 20 to 10,000 micrometers.
• Sympatec's standard chute for guiding particles into the instrument was modified by removing the flights within the chute and by attaching a funnel to the top of the chute.
• the funnel is constructed of stainless steel and has 4 trapezoidal sides, 14 inches across the wide part (top), tapering to 2 inches wide at the bottom, i.e. point of attachment with the chute.
• the trapezoid sides are 12 inches long.
• a vacuum is attached to the exit of the instrument to create an air flow through the instrument, and consequently the chute and the funnel.
• the vacuum is sufficient to create an airspeed entering the funnel of 470 feet/min.
• the airspeed is measured using an Extech Instruments ThermoAnemometer Model 407113 and Anemometer metal probe, SN Q138487.
• the probe was mounted in a plastic tube in a square of foam (necessitated by the square shape of the funnel).
• the probe assembly was placed in the funnel so that the foam sealed against the funnel walls and the anemometer was centered above the shaft opening.
• the linear flow was calculated for the bottom of the funnel where the drop shaft begins (the 2′′x2′′ opening).
• sanitary tissue product is dispensed, i.e. pulled apart at the perforations, manually at the top of the funnel to release dust.
• the force to rupture the product at the perforations is a function of the dispensing tensile and the operator merely applies enough force directly in tension across the perforations to dispense the product in a manner typical of tissue dispensing. Care should be taken not to tear the product across any perforations, rather it should be dispensed by pulling directly in tension across the perforations.
• the dust fibers and/or particles so liberated are directed into a modified Sympatec chute and the chute, delivers them to the measurement zone of the instrument by gravity and vacuum.
• the QICPIC measures the number of particles passing through the measurement zone using dynamic image analysis. Five perforations are separated per measurement and the Raw Dispensing Dust value is simply the total number of particles counted.
• the raw data needs to be normalized for width of the product at the perforations.
• the Raw Dispensing Dust value is multiplied by the width of the product at the perforations in inches and divided by 4.27. This result is the Dispensing Dust value.
• Products more than about 6′′ wide should be precut in width with scissors to 4.27 inches wide prior to testing to prevent being too wide to dispense properly in tension.
• the Normalized Dispensing Dust value is determined by any one of the following relationships: 1) Dispensing Dust value divided by Dispensing Tensile and multiplied by 150 yields the Tensile Normalized Dispensing Dust value; 2) Dispensing Dust Value divided by Lint test result and multiplied by 7 yields the Lint Normalized Dispensing Dust value; and 3) Dispensing Dust value divided by the product Density and multiplied by 0.08 yields the Density Normalized Dispensing Dust value.
• the calculated dust valves as related to the application rate to the paper web (in lb/ton) and application method (spray, extrusion, or printing) compared to a non-treated paper web area provided in Table 1 below.
• the paper samples to be tested should be conditioned according to Tappi Method #T4020M-88.
• samples are preconditioned for 24 hours at a relative humidity level of 10 to 35% and within a temperature range of 22° to 40° C.
• samples should be conditioned for 24 hours at a relative humidity of 48 to 52% and within a temperature range of 22° C. to 24° C.
• the softness panel testing should take place within the confines of a constant temperature and humidity room. If this is not feasible, all samples, including the controls, should experience identical environmental exposure conditions.
• Softness testing is performed as a paired comparison in a form similar to that described in “Manual on Sensory Testing Methods”, ASTM Special Technical Publication 434, published by the American Society for Testing and Materials 1968 and is incorporated herein by reference. Softness is evaluated by subjective testing using what is referred to as a Paired Difference Test. The method employs a standard external to the test material itself. For tactile perceived softness two samples are presented such that the subject cannot see the samples, and the subject is required to choose one of them on the basis of tactile softness. The result of the test is reported in what is referred to as Panel Score Unit (PSU). With respect to softness testing to obtain the softness data reported herein in PSU, a number of softness panel tests are performed.
• PSU Panel Score Unit
• each test ten practiced softness judges are asked to rate the relative softness of three sets of paired samples.
• the pairs of samples are judged one pair at a time by each judge: one sample of each pair being designated X and the other Y.
• each X sample is graded against its paired Y sample as follows:
• a grade of plus one is given if X is judged to may be a little softer than Y, and a grade of minus one is given if Y is judged to may be a little softer than X;
• a grade of plus two is given if X is judged to surely be a little softer than Y, and a grade of minus two is given if Y is judged to surely be a little softer than X;
• a grade of plus four is given to X if it is judged to be a whole lot softer than Y, and a grade of minus 4 is given if Y is judged to be a whole lot softer than X.
• the grades are averaged and the resultant value is in units of PSU.
• the resulting data are considered the results of one panel test. If more than one sample pair is evaluated then all sample pairs are rank ordered according to their grades by paired statistical analysis. Then, the rank is shifted up or down in value as required to give a zero PSU value to which ever sample is chosen to be the zero-base standard. The other samples then have plus or minus values as determined by their relative grades with respect to the zero base standard.
• the number of panel tests performed and averaged is such that about 0.2 PSU represents a significant difference in subjectively perceived softness.
• the tensile strength should be converted into a “specific total tensile strength” defined as the sum of the tensile strength measured in the machine and cross machine directions, divided by the basis weight, and corrected in units to a value in meters.

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• 2007
  • 2007-05-03 US US11/799,890 patent/US20080271867A1/en not_active Abandoned
• 2008
  • 2008-04-28 WO PCT/IB2008/051643 patent/WO2008135901A2/en not_active Ceased
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