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N:
 N21:
  N21H: INDEXING SCHEME RELATING TO PULP COMPOSITIONS, THE PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D, THE IMPREGNATING OR COATING OF PAPER, THE TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G, AND TO PAPER NOT OTHERWISE PROVIDED FOR
   N21H1/00: IPC4 Paper; Cardboard (fibreboard D21J)
   N21H1/02: IPC 4 Multi-ply material finished plies
   N21H1/04: . . IPC 4 by using an adhesive
   N21H1/06: . . IPC 4 Apparatus
   N21H1/08: . . IPC 4 with incorporated laminae of threads or fabric
   N21H3/00: IPC4 Paper or cardboard prepared by adding substances to the pulp or to the formed web on the paper-making machine and by applying substances to finished paper or cardboard (on the paper-making machine), also when the intention is to impregnate at least a part of the paper body
   N21H3/82: IPC 4 by adding insoluble coloured substances, e.g. powders, fibres, pieces of metal, for obtaining different colours in the paper fancy papers; substances characterised by their physical appearance, e.g. form, rather than by their chemical constitution
   N21H3/82B: . . substances having a characteristic form, e.g. powders, disintegrated resin foams
   N21H5/00: IPC4 Special paper or cardboard not otherwise provided for (duplicating or recording paper B41M)
   N21H5/00B: Flame-resistant papers; (complex) compositions rendering paper fire-resistant
   N21H5/00C: Processes or apparatus specially adapted for applying liquids or other fluent materials to finished paper or board, e.g. impregnating, coating applying liquids to surfaces in general B05; treating textile materials by liquids, gases or vapours D06B; processes for adding substances to the wet pulp or to the formed web on the paper-making machine D21D3/00; impregnated or coated fibreboard D21J1/08; apparatus for making patterned paper D21H5/06; printing machines B41F
   N21H5/00C10: . . by contact with a device carrying the treating material C8 and C12 take precedence
   N21H5/00C10B: . . . by a rubbing device, e.g. with brushes or pads
   N21H5/00C10D: . . . with a roller
   N21H5/00C10D2: . . . . Details thereof, e.g. surface characteristics, peripheral speed
   N21H5/00C10D2B: . . . . . the coating material on the applicator roller being subjected to a particular treatment before applying to paper
   N21H5/00C10D2D: . . . . . Reverse roll coating, e.g. applicator surface moving in direction opposite to that of paper
   N21H5/00C10F: . . . the treating material being non-fluent at the moment of transfer, e.g. in form of preformed, at least partially hardened, coating
   N21H5/00C12: . . by pouring or allowing to flow in a continuous stream onto the surface, the entire stream being carried away by the paper
   N21H5/00C12B: . . . Falling curtain method
   N21H5/00C14: . . by spraying or projecting D21H5/00C8D2 takes precedence
   N21H5/00C16: . . involving several different techniques of application treatments in which the characteristics of a single treatment are of interest only, or in which all treatments have characteristics provided for in a single sub-group, see the relevant sub-groups for the single treatment; several superposed coatings D21H19/82; impregnated as well as coated paper D21H5/00K; apparatus for making multi-ply material D21H1/06
   N21H5/00C16B: . . . Plural serial stages
   N21H5/00C16D: . . . Plural parallel stages
   N21H5/00C16F: . . . Apparatus permitting switching from one technique to another
   N21H5/00C18: . . Controlling or regulating controlling or regulating in general G05
   N21H5/00C18B: . . . Regulating the amount or the distribution, e.g. smoothing, of essentially fluent material already applied to the paper; Recirculating excess coating material applied to paper after-treatment D21H25/00 to D21H25/18
   N21H5/00C18B2: . . . . with blades trailing blade D21H5/00C8B2
   N21H5/00C18B4: . . . . with an essentially cylindrical body, e.g. roll or rod
   N21H5/00C18B6: . . . . with a blast of gas or vapour, e.g. air knife
   N21H5/00C2: . . Pretreatment of paper to which liquids or other fluent materials are to be applied
   N21H5/00C4: . . by treating paper or board in discontinuous form, e.g. separate sheets, blanks, paper rolls, or the like
   N21H5/00C8: . . by bringing paper into contact with an excess of fluids, the paper carrying away only a part of the fluid material e.g. by passing through liquids, gases or vapours
   N21H5/00C8B: . . . only one side of the paper being in contact with the treating medium, e.g. paper carried by support
   N21H5/00C8B2: . . . . Trailing blade coaters, e.g. blade engaging paper and forming bottom wall of reservoir
   N21H5/00C8D: . . . the paper being at least partly surrounded by treating medium on both sides
   N21H5/00C8D2: . . . . treating medium being a gas or vapour
   N21H5/00D: Anti-slip papers
   N21H5/00F: Anti-friction, anti-abrasive or release paper (processes for obtaining an anti-friction or anti-adhesive surfaceB05D5/08; adhesive materials on paper characterised by the release coating compositionC09J7/04H)
   N21H5/00G: Transparent papers, e.g. paper treated with transparent-rendering compositions or glassine paper prepares from well-hydrated stock paper with watermarks B41M3/10; watermaking devices D21F1/44
   N21H5/00H: characterised by the use of special fibrous materials as well as special compounds use of special fibrous materials D21H5/12; adding substances to the pulp or to the formed web D21H3/00
   N21H5/00M: Wall papers printed wallpapers B41M3/18; pregummed wall paper C09J7/04
   N21H5/00P: Paper for surface-protection and decorative purposes, e.g. pressure laminates wall paper D21H5/00M; multi-ply material D21H1/02
   N21H5/00P4: . . Aspect concerning the core layer(s)
   N21H5/00P6: . . Aspect concerning the anchor layer(s)
   N21H5/00R: Post-treated paper after-treatment following application of substances to finished paper D21H25/00 to D21H25/18, D21H5/00C18B; after-treatment of printed works B41M7/00; working paper B31F; paper from fibres which can be modified D21H5/12R
   N21H5/00R2: . . with means capable of destructing or weakening the paper structure, e.g. cellulose decomposing agents working-up waste paper D21C5/02
   N21H5/00R4: . . with means restoring or reinforcing the paper-structure preserving paintings B44D7/00; multi-ply material with incorporated laminae of threads or fabric D21H1/08
   N21H5/02: IPC 4 Patterned paper
   N21H5/02B: . . Webs provided with apertures
   N21H5/04: . . IPC 4 marbled
   N21H5/06: . . IPC 4 Apparatus
   N21H5/08: IPC 4 Vegetable parchment
   N21H5/12: IPC 4 characterised by the use of special fibrous materials
   N21H5/12B: . . of protein fibres
   N21H5/12D: . . of crimped or crimpable fibres
   N21H5/12F: . . of polysaccharide fibres other than cellulosic, e.g. alginate fibres
   N21H5/12G: . . of fibres which have been treated to render them suitable for sheet formation, e.g. fibrillatable fibres
   N21H5/12H: . . of long or continuous filaments
   N21H5/12M: . . of fibres which have been treated to improve their dispersion in the paper-making furnish
   N21H5/12P: . . of fibres which have been swollen
   N21H5/12R: . . of fibres which can be physically or chemically modified during or after web formation after treatment of coated or impregnated papers D21H25/00 to D21H25/18
   N21H5/12R2: . . . by chemical treatment
   N21H5/12R4: . . . by thermal treatment
   N21H5/14: . . IPC 4 of cellulose fibres only
   N21H5/14B: . . . of fibrous cellulose derivatives
   N21H5/14B4: . . . . grafted or encapsulated cellulose
   N21H5/14B8: . . . . cellulose esters
   N21H5/14B8B: . . . . . cellulose acetate
   N21H5/14D: . . . viscose
   N21H5/16: . . . IPC 4 Tobacco or cigarette paper
   N21H5/18: . . IPC 4 of inorganic fibres with or without cellulose fibres
   N21H5/18D: . . . of asbestos fibres
   N21H5/18G: . . . of mica fibres or flakes
   N21H5/20: . . IPC 4 of organic non-cellulosic fibres too short for spinning, with or without cellulose fibres
   N21H5/20D: . . . polyolefins
   N21H5/20P: . . . acrylic fibres
   N21H5/20R: . . . polyester fibres
   N21H5/22: IPC 4 Fungicidal, bactericidal, insecticidal, disinfecting, antiseptic, or corrosion-inhibiting paper antistatic, antioxygenic paper toilet paper A47K10/16
   N21H5/24: IPC 4 having enhanced flexibility or extensibility produced by mechanical treatment of the unfinished paper
   N21H5/24B: . . obtained by compressing the (moist) paper in directions lying in, and optionally perpendicular to, the paper plane, e.g. plain-surfaced Clupak papers
   N21H5/26: IPC 4 Special paper or cardboard manufactured by dry method; Apparatus or processes for forming webs by dry method from mainly short-fibre or particle material, e.g. paper pulp making board from wood, e.g. lignocellulosic, particles or fibres B27N1/00 and subgroups; making non-woven fabrics from textile fibres D04H1/72; machines for forming diapers A61F13/15M2; lap-forming devices in preliminary treatment of fibres, e.g. for spinning D01G25/00
   N21H5/26B: . . Pretreatment and individualisation of the fibres, formation of the mixture fibres-gas and laying the fibres on a forming surface manufacture of a pulp sheet or dewatered pulp D21C9/18B
   N21H5/26B2: . . . Detachment of the fibres from their compressed state, e.g. by disintegration of a pulpboard mechanical treatment of fibrous raw materials by dry methods D21B1/06
   N21H5/26B4: . . . Distribution of the fibres in the gas stream and on the forming surface
   N21H5/26B6: . . . Formation of a product from several constituents, e.g. blends of various types of fibres, fillers and/or binders or formation from various sources and/or streams or fibres mixing non-fibrous materials with fibres as a preliminary treatment of fibres, e.g. for spinning D01G13/00
   N21H5/26B6B: . . . . forming a final homogeneous product
   N21H5/26B6D: . . . . forming a final non-homogeneous product
   N21H5/26D: . . Treatment of the formed web
   N21H5/26D2: . . . Consolidation
   N21H5/26D2B: . . . . Addition of a binder, e.g. synthetic resins or water
   N21H5/26D2D: . . . . Compression of the web, optionally with the use of a binder
   N21H5/26F: . . Manufacture of layered products (assembly of superposed sheets), comprising the consolidation of such a structure formation of a web by dry method directly on to other webs formed solely by dry method D21H5/26B6 and subgroups
   N21H5/26F2: . . . by dry method on to a web or on or between several preformed webs, at least one of which has been formed by another method, e.g. by wet method
   N21H5/26F4: . . . Assembly of several preformed webs, at least one of which has been formed by dry method
   N21H11/00: Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
   N21H11/02: Chemical, chemomechanical or chemothermomechanical pulp
   N21H11/04: . . Kraft or sulfate pulp
   N21H11/06: . . Sulfite or bisulfite pulp
   N21H11/08: Mechanical or thermomechanical pulp
   N21H11/10: Mixtures of chemical and mechanical pulp
   N21H11/12: Pulp from non-woody plants or crops, e.g. cotton, flax, straw, bagasse
   N21H11/14: Secondary fibres
   N21H11/16: modified by a particular after-treatment
   N21H11/18: . . Highly hydrated, swollen or fibrillatable fibres
   N21H11/20: . . Chemically or biochemically modified fibres
   N21H11/22: . . . cationised
   N21H13/00: Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
   N21H13/02: Synthetic cellulose fibres
   N21H13/04: . . Cellulose ethers
   N21H13/06: . . Cellulose esters
   N21H13/08: . . from regenerated cellulose
   N21H13/10: Organic non-cellulose fibres
   N21H13/12: . . from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
   N21H13/14: . . . Polyalkenes, e.g. polystyrene
   N21H13/16: . . . Polyalkenylalcohols; Polyalkenylethers; Polyalkenylesters
   N21H13/18: . . . Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylonitriles
   N21H13/20: . . from macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
   N21H13/22: . . . Condensation polymers of aldehydes or ketones
   N21H13/24: . . . Polyesters
   N21H13/26: . . . Polyamides; Polyimides
   N21H13/28: . . from natural polymers
   N21H13/30: . . . Non-cellulose polysaccharides
   N21H13/32: . . . . Alginate fibres
   N21H13/34: . . . Protein fibres
   N21H13/36: Inorganic fibres or flakes
   N21H13/38: . . siliceous
   N21H13/40: . . . vitreous, e.g. mineral wool, glass fibres
   N21H13/42: . . . Asbestos
   N21H13/44: . . . Flakes, e.g. mica, vermiculite
   N21H13/46: . . Non-siliceous fibres, e.g. from metal oxides
   N21H13/48: . . . Metal or metallised fibres
   N21H13/50: . . . Carbon fibres
   N21H15/00: Pulp or paper, comprising fibres or web-forming material characterised by features other than their chemical constitution
   N21H15/02: characterised by configuration
   N21H15/04: . . crimped, kinked, curled or twisted fibres
   N21H15/06: . . Long fibres, i.e. fibres exceeding the upper length limit of conventional paper-making fibres; Filaments
   N21H15/08: . . Flakes
   N21H15/10: . . Composite fibres
   N21H15/12: . . . partly organic, partly inorganic
   N21H17/00: Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
   N21H17/00B: Micro-organisms or enzymes
   N21H17/01: Waste products, e.g. sludge
   N21H17/02: Material of vegetable origin
   N21H17/03: Non-macromolecular organic compounds
   N21H17/04: . . Hydrocarbons
   N21H17/05: . . containing elements other than carbon and hydrogen only
   N21H17/06: . . . Alcohols; Phenols; Ethers; Aldehydes; Ketones; Acetals; Ketals
   N21H17/07: . . . Nitrogen-containing compounds
   N21H17/08: . . . . Isocyanates
   N21H17/09: . . . Sulfur-containing compounds
   N21H17/10: . . . Phosphorus-containing compounds
   N21H17/11: . . . Halides
   N21H17/12: . . . Organo-metallic compounds
   N21H17/13: . . . Silicon-containing compounds
   N21H17/14: . . . Carboxylic acids; Derivatives thereof
   N21H17/15: . . . . Polycarboxylic acids, e.g. maleic acid
   N21H17/16: . . . . . Addition products thereof with hydrocarbons
   N21H17/17: . . . Ketenes, e.g. ketene dimers
   N21H17/18: . . . forming new compounds in situ, e.g. within the pulp or paper, by chemical reaction with itself, or other added substances, by grafting on the fibres
   N21H17/19: . . . . by reactions only involving carbon-to-carbon unsaturated bonds
   N21H17/20: Macromolecular organic compounds
   N21H17/21: . . of natural origin; Derivatives thereof
   N21H17/22: . . . Proteins
   N21H17/23: . . . Lignins
   N21H17/24: . . . Polysaccharides
   N21H17/25: . . . . Cellulose
   N21H17/26: . . . . . Ethers thereof
   N21H17/27: . . . . . Esters thereof
   N21H17/28: . . . . Starch
   N21H17/29: . . . . . cationic
   N21H17/30: . . . . Alginic acid or alginates
   N21H17/31: . . . . Gums
   N21H17/32: . . . . . Guar or other polygalactomannan gum
   N21H17/33: . . Synthetic macromolecular compounds
   N21H17/34: . . . obtained by reactions only involving carbon-to-carbon unsaturated bonds
   N21H17/35: . . . . Polyalkenes, e.g. polystyrene
   N21H17/36: . . . . Polyalkenyalcohols; Polyalkenylethers; Polyalkenylesters
   N21H17/37: . . . . Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
   N21H17/37B: . . . . . Poly(meth)acrylamide
   N21H17/38: . . . . containing crosslinkable groups
   N21H17/39: . . . . . forming ether crosslinkages, e.g. alkylol groups
   N21H17/40: . . . . . unsaturated
   N21H17/41: . . . . containing ionic groups
   N21H17/42: . . . . . anionic
   N21H17/43: . . . . . . Carboxyl groups or derivatives thereof
   N21H17/44: . . . . . cationic
   N21H17/45: . . . . . . Nitrogen-containing groups
   N21H17/45B: . . . . . . . comprising tertiary amine or being at least partially quaternised
   N21H17/46: . . . obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
   N21H17/47: . . . . Condensation polymers of aldehydes or ketones
   N21H17/48: . . . . . with phenols
   N21H17/49: . . . . . with compounds containing hydrogen bound to nitrogen
   N21H17/50: . . . . . . Acyclic compounds
   N21H17/51: . . . . . . Triazines, e.g. melamine
   N21H17/52: . . . . Epoxy resins
   N21H17/53: . . . . Polyethers; Polyesters
   N21H17/54: . . . . obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen
   N21H17/55: . . . . . Polyamides; Polyaminoamides; Polyester-amides
   N21H17/56: . . . . . Polyamines; Polyimines; Polyester-imides
   N21H17/57: . . . . . Polyureas; Polyurethanes
   N21H17/58: . . . . obtained by reactions forming in the main chain of the macromolecule a linkage containing sulfur
   N21H17/59: . . . . obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon
   N21H17/60: Waxes
   N21H17/61: Bitumen
   N21H17/62: Rosin; Derivatives thereof
   N21H17/63: Inorganic compounds
   N21H17/64: . . Alkaline compounds
   N21H17/65: . . Acid compounds
   N21H17/66: . . Salts, e.g. alums
   N21H17/67: . . Water-insoluble compounds, e.g. fillers, pigments
   N21H17/67B: . . . Oxides, hydroxides or carbonates
   N21H17/68: . . . siliceous, e.g. clays
   N21H17/69: . . . modified, e.g. by association with other compositions prior to incorporation in the pulp or paper
   N21H17/70: . . forming new compounds in situ, e.g. within the pulp or paper, by chemical reaction with other substances added separately
   N21H17/71: Mixtures of material
   N21H17/72: . . of organic material
   N21H17/73: . . of inorganic material
   N21H17/74: . . of organic and inorganic material
   N21H19/00: Coated paper; Coating material
   N21H19/02: Metal coatings
   N21H19/04: . . applied as foil
   N21H19/06: . . applied as liquid or powder
   N21H19/08: . . applied as vapour, e.g. in vacuum
   N21H19/10: Coatings without pigments
   N21H19/12: . . applied as a solution using water as the only solvent, e.g. in the presence of acid or alkaline compounds
   N21H19/14: . . applied in a form other than the aqueous solution defined in group N21H19/12
   N21H19/16: . . . comprising curable or polymerisable compounds
   N21H19/18: . . . comprising waxes
   N21H19/20: . . . comprising macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
   N21H19/22: . . . . Polyalkenes, e.g. polystyrene
   N21H19/24: . . . comprising macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
   N21H19/26: . . . . Aminoplasts
   N21H19/28: . . . . Polyesters
   N21H19/30: . . . . Polyamides; Polyimides
   N21H19/32: . . . . obtained by reactions forming a linkage containing silicon in the main chain of the macromolecule
   N21H19/34: . . . comprising cellulose or derivatives thereof
   N21H19/36: Coatings with pigments
   N21H19/38: . . characterised by the pigments
   N21H19/38B: . . . Oxides, hydroxides or carbonates
   N21H19/40: . . . siliceous, e.g. clays
   N21H19/42: . . . at least partly organic
   N21H19/44: . . characterised by the other ingredients, e.g. the binder or dispersing agent
   N21H19/46: . . . Non-macromolecular organic compounds
   N21H19/48: . . . . Diolefins, e.g. butadiene; Aromatic vinyl monomers, e.g. styrene; Polymerisable unsaturated acids or derivatives thereof, e.g. acrylic acid
   N21H19/50: . . . Proteins
   N21H19/52: . . . Cellulose; Derivatives thereof
   N21H19/54: . . . Starch
   N21H19/56: . . . Macromolecular organic compounds or oligomers thereof obtained by reactions only involving carbon-to-carbon unsaturated bonds
   N21H19/58: . . . . Polymers or oligomers of diolefins, aromatic vinyl monomers or unsaturated acids or derivatives thereof
   N21H19/60: . . . . Polyalkenylalcohols; Polyalkenylethers; Polyalkenylesters
   N21H19/62: . . . Macromolecular organic compounds or oligomers thereof obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
   N21H19/64: . . . Inorganic compounds
   N21H19/66: Coatings characterised by a special visual effect, e.g. patterned, textured
   N21H19/68: . . uneven, broken, discontinuous
   N21H19/70: . . with internal voids, e.g. bubble coatings
   N21H19/72: Coated paper characterised by the paper substrate
   N21H19/74: . . the substrate having an uneven surface, e.g. crÍped or corrugated paper
   N21H19/76: . . the substrate having specific absorbent properties
   N21H19/78: . . . being substantially impervious to the coating
   N21H19/80: Paper comprising more than one coating
   N21H19/82: . . superposed
   N21H19/82B: . . . two superposed coatings, both being pigmented
   N21H19/82D: . . . two superposed coatings, both being non-pigmented
   N21H19/82F: . . . two superposed coatings, the first applied being pigmented andthe second applied being non-pigmented
   N21H19/82H: . . . two superposed coatings, the first applied being non-pigmented and the second applied being pigmented
   N21H19/84: . . on both sides of the substrate
   N21H21/00: 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
   N21H21/02: Agents for preventing deposition on the paper mill equipment, e.g. pitch or slime control
   N21H21/04: . . Slime-control agents
   N21H21/06: Paper forming aids
   N21H21/08: . . Dispersing agents for fibres
   N21H21/10: . . Retention agents or drainage improvers
   N21H21/12: . . Defoamers
   N21H21/14: characterised by function or properties in or on the paper
   N21H21/14B: . . Agents preventing ageing of paper, e.g. radiation absorbing substances
   N21H21/14D: . . CrÍping adhesives
   N21H21/16: . . Sizing or water-repelling agents
   N21H21/18: . . Reinforcing agents
   N21H21/20: . . . Wet strength agents
   N21H21/22: . . Agents rendering paper porous, absorbent or bulky
   N21H21/24: . . . Surfactants
   N21H21/26: . . Agents rendering paper transparent or translucent
   N21H21/28: . . Colorants, pigments or opacifying agents
   N21H21/28B: . . . insoluble
   N21H21/30: . . Luminescent or fluorescent substances, e.g. for optical bleaching
   N21H21/32: . . Bleaching agents
   N21H21/34: . . Ignifugeants
   N21H21/36: . . Biocidal agents, e.g. fungicidal, bactericidal, insecticidal agents
   N21H21/38: . . Corrosion-inhibiting agents or anti-oxidants
   N21H21/40: . . Agents facilitating proof of genuineness or preventing fraudulent alteration, e.g. for security paper
   N21H21/42: . . . Ribbons or strips
   N21H21/44: . . . Latent security elements, i.e. detectable or becoming apparent only by use of special verification or tampering devices or methods
   N21H21/46: . . . . Elements suited for chemical verification or impeding chemical tampering, e.g. by use of eradicators
   N21H21/48: . . . . Elements suited for physical verification, e.g. by irradiation
   N21H21/50: characterised by form
   N21H21/52: . . Additives of definite length or shape
   N21H21/54: . . . being spherical, e.g. microcapsules, beads
   N21H21/56: . . Foam
   N21H23/00: Processes or apparatus for adding material to the pulp or to the paper
   N21H23/02: characterised by the manner in which substances are added
   N21H23/04: . . Addition to the pulp; After-treatment of added substances in the pulp
   N21H23/06: . . . Controlling the addition
   N21H23/08: . . . . by measuring pulp properties, e.g. zeta potential, pH
   N21H23/10: . . . . . at least two kinds of compounds being added
   N21H23/12: . . . . by measuring properties of the formed web
   N21H23/14: . . . . by selecting point of addition or time of contact between components
   N21H23/16: . . . . . Addition before or during pulp beating or refining
   N21H23/18: . . . . . Addition at a location where shear forces are avoided before sheet-forming, e.g. after pulp beating or refining
   N21H23/20: . . . Apparatus therefor
   N21H23/22: . . Addition to the formed paper
   N21H23/24: . . . during paper manufacture
   N21H23/26: . . . . by selecting point of addition or moisture content of the paper
   N21H23/28: . . . . . Addition before the dryer section, e.g. at the wet end or press section
   N21H23/30: . . . Pretreatment of the paper
   N21H23/32: . . . by contacting paper with an excess of material, e.g. from a reservoir or in a manner necessitating removal of applied excess material from the paper
   N21H23/34: . . . . Knife or blade type coaters
   N21H23/36: . . . . . Knife or blade forming part of the fluid reservoir, e.g. puddle-type trailing blade or short-dwell coaters
   N21H23/38: . . . . . the fluid material being applied with a special device, e.g. with a roll in a flooded-nip inverted blade coater
   N21H23/40: . . . . only one side of the paper being in contact with the material
   N21H23/42: . . . . Paper being at least partly surrounded by the material on both sides
   N21H23/44: . . . . . Treatment with a gas or vapour
   N21H23/46: . . . Pouring or allowing the fluid to flow in a continuous stream on to the surface, the entire stream being carried away by the paper
   N21H23/48: . . . . Curtain coaters
   N21H23/50: . . . Spraying or projecting
   N21H23/52: . . . by contacting paper with a device carrying the material
   N21H23/54: . . . . Rubbing devices, e.g. brush, pad, felt
   N21H23/56: . . . . Rolls
   N21H23/58: . . . . . Details thereof, e.g. surface characteristics, peripheral speed
   N21H23/60: . . . . . . the material on the applicator roll being subjected to a particular treatment before applying to the paper
   N21H23/62: . . . . . . Reverse roll coating, i.e. applicator roll surface moving in direction opposite to that of the paper
   N21H23/64: . . . . the material being non-fluent at the moment of transfer, e.g. in form of preformed, at least partially hardened coating
   N21H23/66: . . . Treating discontinuous paper, e.g. sheets, blanks, rolls
   N21H23/68: . . . . whereby the paper moves continuously
   N21H23/70: . . . Multistep processes; Apparatus for adding one or several substances in portions or in various ways to the paper, not covered by another single group of this main group
   N21H23/72: . . . . Plural serial stages only
   N21H23/74: . . . . Apparatus permitting switching from one technique to another
   N21H23/76: 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
   N21H23/76B: . . Addition of all compounds to the pulp
   N21H23/78: Controlling or regulating not limited to any particular process or apparatus
   N21H25/00: After-treatment of paper not provided for in groups N21H17/00 to N21H23/00
   N21H25/00B: Mechanical treatment
   N21H25/02: Chemical or biochemical treatment
   N21H25/04: Physical treatment, e.g. heating, irradiating
   N21H25/06: . . of impregnated or coated paper
   N21H25/08: Rearranging applied substances, e.g. metering, smoothing; Removing excess material
   N21H25/10: . . with blades
   N21H25/12: . . with an essentially cylindrical body, e.g. roll or rod
   N21H25/14: . . . the body being a casting drum, a heated roll or a calender
   N21H25/16: . . with a blast of vapour or gas, e.g. air knife
   N21H25/18: of old paper as in books, documents, e.g. restoring
   N21H27/00: Special paper not otherwise provided for, e.g. made by multi-step processes
   N21H27/00B: Release paper
   N21H27/00D: Tissue paper; Absorbent paper
   N21H27/00D2: . . characterised by specific parameters
   N21H27/00D2B: . . . relating to physical or mechanical properties, e.g. tensile strength, stretch, softness
   N21H27/00D2B2: . . . . relating to absorbency, e.g. amount or rate of water absorption, optionally in combination with other parameters relating to physical or mechanical properties
   N21H27/00D4: . . characterised by inhomogeneous distribution or incomplete coverage of properties, e.g. obtained by using materials or chemical compounds
   N21H27/02: Patterned paper
   N21H27/04: . . marbled
   N21H27/06: Vegetable or imitation parchment; Glassine paper
   N21H27/08: Filter paper
   N21H27/10: Packing paper
   N21H27/14: Paper having stable form or dimension; Curl-resistant paper
   N21H27/16: Pure paper, i.e. paper lacking or having low content of contaminants
   N21H27/18: Paper- or board-based structures for surface covering
   N21H27/20: . . Flexible structures being applied by the user, e.g. wallpaper
   N21H27/22: . . Structures being applied on the surface by special manufacturing processes, e.g. in presses
   N21H27/24: . . . characterised by the surface to be covered being phenolic-resin paper laminates, vulcan fibre or similar cellulosic fibreboards
   N21H27/26: . . . characterised by the overlay sheet or the top layers of the structures
   N21H27/28: . . . . treated to obtain specific resistance properties, e.g. against wear or weather
   N21H27/30: Multi-ply
   N21H27/32: . . with materials applied between the sheets
   N21H27/34: . . . Continuous materials, e.g. filaments, sheets, nets
   N21H27/36: . . . . Films made from synthetic macromolecular compounds
   N21H27/38: . . at least one of the sheets having a fibrous composition differing from that of other sheets
   N21H27/40: . . at least one of the sheets being non-planar, e.g. crÍped
   N21H27/42: . . comprising dry-laid paper