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
  • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
  • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
  • D21H23/04—Addition to the pulp; After-treatment of added substances in the pulp
  • D21H23/06—Controlling the addition
  • D21H23/14—Controlling the addition by selecting point of addition or time of contact between components
  • D21H23/18—Addition at a location where shear forces are avoided before sheet-forming, e.g. after pulp beating or refining
• • 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
  • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
  • D21H23/22—Addition to the formed paper
  • D21H23/24—Addition to the formed paper during paper manufacture
  • D21H23/26—Addition to the formed paper during paper manufacture by selecting point of addition or moisture content of the paper
  • D21H23/28—Addition before the dryer section, e.g. at the wet end or press section

Definitions

• the present invention relates to paper sizing methods and is more particularly concerned with the sizing of paper using rosin-based sizing compositions at relatively high pH values.
• the invention also relates to sizing compositions per se, for use in carrying out such methods, and the resultant sized paper products.
• the present invention is based upon the unexpected discovery of a difference in behaviour if a pre-mix of rosin and an aluminium salt is made when or just before it is in fact used, as compared with known methods where it is made a considerable time before its use.
• a paper sizing method in which paper is made from a pulp system containing chalk or otherwise having a neutral or alkaline and therefore high pH, in which a pre-blended composition containing a rosin-based size and an aluminium compound is used or the rosin-based sizing composition and the aluminium compound are added separately but simultaneously and are pre-mixed just prior to addition at an appropriate selected point in the paper machine wet-end.
• a pre-blended paper sizing composition comprising a rosin-based size and an aluminium compound and suitable for use on or immediately after its formulation.
• Particular optional but preferred features of the proposed one-shot paper sizing composition of the present invention may include the incorporation into the composition of a higher than normal amount of aluminium salt, a higher than normal amount of the rosin-based size or the inclusion of at least one polyelectrolyte.
• the weight ratio of the rosin size to the aluminium compound, used in carrying out the method and accordingly present in the one-shot composition, on a dry basis lies in the ratio 1:0.01 to 5.
• the ingredients added to the paper machine wet-end in carrying out the method of the invention, either during operation or as a one-shot pre-mix include at least one urea-based extender.
• another aspect consists in the use of pre-mixed compositions and techniques, of the kind indicated above, in the surface sizing of paper which has already been manufactured, whether or not a rosin-based sizing composition has been used in its manufacture up to that stage.
• a further aspect of the present invention consists of any paper or paper-­like product made by a method according to the present invention or made using a paper-sizing composition according to the invention.
• a pre-mixed rosin-based sizing composition for use in carrying out the present invention may contain, in addition to the rosin and the aluminium compound, one or more other additives useful in the making of paper, for instance for optimising the sizing function of the rosin-based component per se.
• additional and optional additives include cationic and anionic polyelectrolytes, and also cationic starches.
• the pre-mix can contain one or more of cationic and anionic polyacrylamides, polyethyleneimine, polydialkyl dimethyl ammonium chloride (DADMAC) or polyamide/epichlorohydrin condensates, as well as dicyandiamide/formaldehyde condensation products.
• DADMAC polydialkyl dimethyl ammonium chloride
• dicyandiamide/formaldehyde condensation products can contain one or more of cationic and anionic polyacrylamides, polyethyleneimine, polydialkyl dimethyl ammonium chloride (DADMAC) or polyamide/epichlorohydrin condensates, as well as dicyandiamide/formaldehyde condensation products.
• pre-mixed one-shot sizing products such as are available commercially, in the form of products made and supplied by chemical companies, are difficult to use, particularly in neutral or alkaline pH circumstances
• the mixing device In order to carry out the method of the invention in practical terms, it is necessary to employ some form of mixing device, so as to control the degree of dispersion of the aluminium salt and the rosin size, which in turn affects its distribution amongst the paper fibres, with optimisation of sizing efficiency.
• the mixing device is suitably associated with the wet-­end of the paper machine and its proper use ensures that the dispersion serves to control the degree of agglomeration of the fibres in the pulp.
• the rosin-based size component employed by being formulated into a pre-mix with an aluminium compound, can be based on rosin or rosin modifications, prior to conversion into a stable emulsion form.
• gum rosin formaldehyde-treated gum rosin or tall oil rosin, fumaric acid-treated gum rosin or tall oil rosin, disproportionated rosin, maleic anhydride-­treated gum rosin or tall oil rosin such as the compounds or any combination of untreated or treated rosin, such as the compounds of the kinds just mentioned.
• esters or part esters of any of any of the above-mentioned forms of rosin, formed with straight chain or polyhydric alcohols can also be used.
• a third possibility is to use any appropriate mixture of any of the aforementioned untreated or treated forms of rosin, including disproportionated rosin and tall oil rosin, together with any one or more of the esters or part esters just described.
• resinous materials other than rosin per se or chemically-modified rosin compounds.
• hydrocarbon resins both of the aromatic and aliphatic varieties, can be used when suitably formulated, in order to carry out the paper-making methods of the present invention.
• Paraffin waxes and microcrystalline waxes may be used in conjunction with any of the above-mentioned rosin or resin-based types of sizing compositions, the particular use of one or other of the possible waxes depending largely upon the properties which may be required in the eventual paper product.
• any appropriate rosin-based sizing emulsion may incorporate one or more extenders.
• extenders may be employed for this purpose.
• Such extenders are disclosed for example in US-A-4022634, 4093779, 4141750, 4025354, 4437894 and 4605445.
• Any appropriate rosin emulsion may also be extended with emulsions of alkyl ketene dimers, prior to or subsequent to pre-­ mixing with the aluminium compound.
• the alkyl ketene dimer emulsions may be stabilised with either cationic starch or cationic or anionic polymers.
• the aluminium compound incorporated in the one-shot pre-mix of the invention or otherwise employed in carrying out paper sizing methods according to the present invention is selected from polyaluminium chlorides, aluminium chlorohydrate, aluminium sulphate (paper makers alum) and any mixture of two or more of the foregoing.
• At least one stabilising agent which may take the form of one or more surface active agents or surfactants.
• Mixtures of stabilising agents or surfactants also can be used. A very wide range of possibilities is available as to the nature of such materials, which can be anionic, non-ionic, cationic or amphoteric.
• One particular class of stabilised emulsion comprises essentially a rosin soap and a protective colloid.
• the rosin-based component namely the rosin soap, can be a sodium, potassium or ammonium soap of rosin or of a modified rosin, together with amine salts of rosins or modified rosins, for instance the amine salts formed with mono-, di- or triethanolamine.
• These stabilisers can be added separately or formed in situ when making up the rosin-based emulsion composition.
• Colloids which can be used to stabilise the resultant product include casein, starch, soya protein and cellulose derivatives, the former being the most preferred, as well as certain polymers, such as polyvinyl pyrrolidone or polyvinyl alcohol (PVA).
• a preferred form of stabilised emulsion consists essentially of the potassium or sodium soap of the rosin or rosin derivative and casein as the stabilising colloid.
• surface active agents or surfactants which can be used in formulating the compositions of this invention include:
• Cationic resin dispersant systems may also be used to stabilise the rosin dispersions of this invention.
• suitable materials include water-soluble polyaminopolyamide/epichlorohydrin resins, water-soluble alkylene-­polyamine/ephichlorohydrin resins and poly(diallyl­amine)/epichlorohydrin resins.
• a pilot Fourdrinier paper machine was used which was operated to produce paper of 85 gsm at 16 kg per hour from softwood/hardwood Kraft furnish loaded with 10% chalk.
• Pre-mixes of the rosin size and aluminium salt were made using a laboratory mixer and were metered just prior to the flow box.
• sheets were made using Kraft pulp containing 10% of chalk.
• the size and the PAC were added separately to the pulp and held for 30 minutes before sheets were made.
• a commercial paper machine producing envelope paper at the rate of 6.8 tonnes per hour with a chalk content varying from 5.8 to 7.8 per cent was sized by pre-blending free rosin size and alum and adding the pre-mix to the forward side of the thick stock head-­box. Throughout the run, the amount of size used (dry basis) was 0.45% and the amount of alum used (dry basis) was 1.93%.
• the invention thus represents a substantial and surprising advance on previous paper sizing methods and compositions.

Landscapes

• Paper (AREA)
• Polymerisation Methods In General (AREA)
• Basic Packing Technique (AREA)
• Making Paper Articles (AREA)
• Medicinal Preparation (AREA)
• Adhesives Or Adhesive Processes (AREA)
• Medicines That Contain Protein Lipid Enzymes And Other Medicines (AREA)

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• 1988
  • 1988-03-18 GB GB888806432A patent/GB8806432D0/en active Pending
• 1989
  • 1989-03-07 EP EP89302253A patent/EP0333368B1/fr not_active Expired - Lifetime
  • 1989-03-07 ES ES89302253T patent/ES2087862T3/es not_active Expired - Lifetime
  • 1989-03-07 AT AT89302253T patent/ATE139281T1/de not_active IP Right Cessation
  • 1989-03-07 DE DE68926632T patent/DE68926632T2/de not_active Expired - Fee Related
  • 1989-03-10 NZ NZ228297A patent/NZ228297A/en unknown
  • 1989-03-13 FI FI891184A patent/FI94974C/fi not_active IP Right Cessation
  • 1989-03-14 ZA ZA891925A patent/ZA891925B/xx unknown
  • 1989-03-15 NO NO891116A patent/NO180345C/no not_active IP Right Cessation
  • 1989-03-17 PT PT90040A patent/PT90040B/pt not_active IP Right Cessation
  • 1989-03-17 JP JP1063988A patent/JP2656830B2/ja not_active Expired - Fee Related
  • 1989-03-17 AU AU31429/89A patent/AU619260B2/en not_active Ceased
  • 1989-03-17 CA CA000594070A patent/CA1325500C/fr not_active Expired - Fee Related
  • 1989-03-17 DK DK198901318A patent/DK173063B1/da not_active IP Right Cessation

Patent Citations (6)

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