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Patent

Novel paper sizing process

TL;DR: In this article, a sizing agent consisting of a cyclic dicarboxylic acid anhydride of formula where R represents a di- or tri-methylene radical and R1 is a hydrophobic group containing more than 5 carbon atoms selected from alkyl, alkenyl, aralkyl or aralkenyl groups.
Abstract: The water resistance of paper is improved by dispersing in the paper pulp a sizing agent consisting of a cyclic dicarboxylic acid anhydride of formula where R represents a di- or tri-methylene radical and wherein R1 is a hydrophobic group containing more than 5 carbon atoms selected from alkyl, alkenyl, aralkyl or aralkenyl groups Substituted succinic and glutaric acid anhydrides fall within the above formula Intimate and uniform dispersion of the sizing agent within the paper pulp is important and may be achieved by agitation, by addition of the sizing agent of the form of an emulsion or by the simultaneous addition of a dispersing agent The sizing agent is preferably added to the pulp in conjunction with a cationic agent which improves the retention in the paper pulp of the sizing agent as well as serving to bring it into intimate contact with the fibres The cationic agent agent may advantageously fulfill the additional function of emulsifier for the sizing agent and suitable compounds for this purpose include primary, secondary, tertiary, and quaternary amine-modified starches, certain nitrogen substituted starch derivatives as well as certain sulphonium and phosphonium starch derivatives Other cationic agents include alum, aluminium chloride, long chain fatty amines, sodium aluminate, polyacrylamide, chomic sulphate, animal glue, certain thermosetting resins and polyamide polymers Non-cationic emulsifiers which may be used to emulsify the sizing agents include such hydrocolloids as ordinary starches, non-cationic starch derivatives, dextrines, carboxymethyl cellulose, gum arabic, gelatin and polyvinyl alcohol In addition certain surfactants such as polyoxyethylene sorbitan trioleate polyoxyethylene sorbitol hexaoleate, polyoxyethylene sorbital laurate, and polyoxyethylene sorbitol oleate laurate may be used as emulsifiers The sizing agents are normally added in amounts ranging from 005 to 5% of the dry weight of the pulp and the cationic agents in amounts ranging from 05 to 20 parts per 10 part by weight of the sizing agent The water resistance of the paper may be further improved by post curing of the finished paper sheet The sizing agents may be used in conjunction with other sizing agents, fillers, pigments or additives such as alum Specification 765,880 is referred to
Citations
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Journal ArticleDOI
TL;DR: A review of the literature related to internal sizing agents can be found in this article, where a variety of studies have quantified ways in which internal sizing treatments tend to be inefficient, compared to what is theoretically possible.
Abstract: This review considers research related to internal sizing agents Such chemicals, when added as emulsions or in micellar form to slurries of cellulosic fibers before paper is made, can make the product resist water and other fluids Significant progress has been achieved to elucidate the modes of action of alkylketene dimer (AKD), alkenylsuccinic anhydride (ASA), rosin products, and other sizing chemicals Recent findings generally support a traditional view that efficient hydrophobation requires that the sizing chemicals contain hydrophobic groups, that they are efficiently retained on fiber surfaces during the papermaking process, that they become well distributed on a molecular scale, and that they need to be chemically anchored A variety of studies have quantified ways in which internal sizing treatments tend to be inefficient, compared to what is theoretically possible The inefficient nature of chemical and physical processes associated with internal sizing, as well as competing reactions and some interfering or contributing factors, help to explain apparent inconsistencies between the results of some recent studies

165 citations

Patent
09 Feb 1976
TL;DR: In this paper, a size mixture comprising a substituted cyclic dicarboxylic acid anhydride and polyoxyalkylene alkyl or alkyls-aryl ether or the corresponding mono- or di-ester is used to size paper products.
Abstract: A size mixture comprising a substituted cyclic dicarboxylic acid anhydride and polyoxyalkylene alkyl or alkyl-aryl ether or the corresponding mono- or di-ester is used to size paper products. In accordance with a preferred embodiment the liquid size mixture is added directly to the paper stock system without prior emulsification.

112 citations

Patent
David H. Dumas1
07 Jul 1983
TL;DR: In this article, sizing compositions in the form of aqueous dispersions comprising a hydrophobic cellulose-reactive sizing agent such as a ketene dimer, fortified rosin and a water-soluble, nitrogen-containing cationic dispersing agent are described.
Abstract: Described are sizing compositions in the form of aqueous dispersions comprising a hydrophobic cellulose-reactive sizing agent such as a ketene dimer, fortified rosin and a water-soluble, nitrogen-containing cationic dispersing agent The compositions are highly efficient internal or surface sizing agents for paper and maximize the advantages of each sizing component while minimizing the disadvantages

76 citations

Patent
28 Nov 1986
TL;DR: A paper size having the ability to be prepared under low shear conditions and having sizing properties superior to the sizes of the prior art may be prepared comprising water and 0.1 to 15% by weight of at least one hydrophobic sizing agent.
Abstract: A paper size having the ability to be prepared under low shear conditions and having sizing properties superior to the sizes of the prior art may be prepared comprising water and 0.1 to 15% by weight of at least one hydrophobic sizing agent and 0.4 to 30% by weight of a jet cooked dispersion of a long chain alkyl derivative of starch or a dispersion of a corresponding gum derivative.

71 citations

Patent
31 Jan 1983
TL;DR: In this article, a composite paper particularly adapted for use as cover sheets in the production of gypsum wallboard is presented, the paper being sufficiently porous to permit better drainage and more rapid drying in production of the paper, and when applied to the surfaces of a gypsuma slurry for forming wallboard, permits less heat to be utilized in the wallboard conversion, thereby saving energy in the board production required for drying the board.
Abstract: A composite paper particularly adapted for use as cover sheets in the production of gypsum wallboard, the paper being sufficiently porous to permit better drainage and more rapid drying in the production of the paper, and when applied to the surfaces of a gypsum slurry for forming wallboard, permits less heat to be utilized in the wallboard conversion, thereby saving energy in the board production required for drying the board. The paper comprises in weight percent: (A) cellulosic fibers in an amount of from about 65% to about 90% and preferably having a fiber freeness of from about 300 ml to about 550 ml Canadian Standard Freeness, (B) calcium sulfate as a filler in an amount of from about 10% to about 35%, (C) a binder in an amount from about 1% to about 31/2%, (D) a flocculant in an amount of from about 0.1% to about 0.2%, (E) a buffering agent in an amount from about 0.25% to about 10%, (F) a neutral sizing agent in an effective amount to prevent water penetration, (G) an anionic polymer in an amount suitable for retaining said filler in said paper, and (H) a cationic starch when a succinic anhydride is used as the neutral sizing agent. In a preferred embodiment, after the paper is treated with a neutral internal sizing agent during its formation, it is subsequently treated with a surface sizing agent after formation of the paper, in order to provide certain properties including better adhesion to the gypsum core when used to make gypsum wallboard.

70 citations

References