[1]2 1 7 6 5 @ 2 2 8 Util'ted States Pateiit Office Patented Or-t. 2, 1956 2,765,228 CELLULOSIC FIBROUS PRODUCTS AND YIETHODS OF PRODUCLNG TFiEi'vli 5 Arthur D. Jordan, Jr., Moorestown, N. J., assignor to Rohm & Haas Company, Philadelphia, Pa., a corporation of Delaware No Drawing. Application March 3,1955, 10 Serial No. 492,041 19 CWms. (Cl. 92-3) This invention relates to improved fibrous products 1,5 containing synthetic linear resins which are characterized by increased dry strengths, particularly increased dry burst, tear, and tensile strengths. It is particularly concerned witli the production of resin-containing fibrous products, such as papers, felts, or other molded fibrous 20 products having increased dry strengths and methods of producing them. in the past, various materials have been applied to fibrous products, especially to aqueous dispersions of paper-making or felt-making fibers prior to the wet lay- 25 ing of such dispersions for the purpose of improving the dry strengths thereof. For example, latices of polychloroprene have been introduced into fiber dispersions, such as in the beater, and the paper or other fibrous products obtained have been choracterized by improved dry 30 strengths. However, the appl-@cation of this type of material also increas,-s tne wet strength so that it prevents "broke" recovery. This characteristic may be an advantao.e where wet strength is desired. However, in many cases, such as in the case (yf pap,-rs or felts intedded 35 for use in suen appl-.Cations as backing or floorin-. or roofing materials ,vhere the sheeted product is subsequently coated or impregnated, high wet strength is unnecessary and the prevention of "broke" recovery because of such wet strength is undesirable. 40 It has now been found that the introduction of relatively smah amounts of water-soluble condensation products of lower alkylene oxides with a polymer of monoethylenically unsaturated monomer molecules comprising carboxylcontaining units are hi.-hly effective for tne improvement 45 of dry strengths of such fibrous products when they are anchored to the fibers forniing the sheet by a polycationic hi.-h molecular weight organic flocculating agent previously adsorbed on the fib@@rs. It has already be@-n suggested that water-insoluble resins and the like can 50 be effectively deposited on paper fibers by s,,ich polycationic agents for improving the stren@.th of paders or the like made therefron. However, to obtain substantial improvements in strength 'Lrom such prior treatments, a comparatively lar.-c amour-t of th.- wat--r-insoluble resin 55 had to be applied, on the order of at least about 10% of the weight of the fiber. In accordance with the present invention, it has been found that from 0.5 to 2% of th@- water-soluble condensates of the present invention impart stren.-th improve- 60 ments that ordin-arily required 10% or more of the heretofore used water-insoluble materials. The use of the water-soluble condensates of the present invention is accompanied by other economies as well, such as the fact that no emulsifier is needed for dispersing them in water. 65 Also, wet strength is not increased excessively so tnat the conden3ates of the present invention do not interfere with broke recovery. While more than 2% of the condensates may be applied, such as up to 10% or 20% of the weight of dly fiber, the use of the hi.-her amounts 70 generally results in no greater benefit and frequently produe,ps diin@hed returns. 2 By "water-soluble" herein is meant to refer to soliibility of the type Nvhich results in colloidal solutions without the aid of a dispersing agent as well as true solubility. The use of emulsifiers or emulsion stabilizing agents of anionig character has the disadvantage that whenever polyvalent metal ions come into contact with the dispersions, whether by accident or otherwise, the dispersions become unstablie and the resin is deposited as flocs or adhesive masses in the pipe lines and tanks which serve for storing and conveying such dispersions. it is an object of the present invention to provide modifie. synthetic linear resins which are flocculated and a-@ichored by the direct action of groups in the polymer upon the poly-cationic flocculating material. In this system, the cationic member not only flocculates the resin but serves to anchor it to the fiber by the formation of a direct bond between the poly-cationic anchoring member and the resin, and by the affinity of the poly-cationic material with the fiber, especially when the fiber is of cellulosic character. Other objects and advantages wffl be apparent from the description hereinafter. In accordance with the present invention, the fibrous material is first treated with a poly-cationic high molecular weight organic nitro.-en compound and then a watersoluble lower alkylene oxide condensate of a synthetic linear polymer compris;ng carlooxyl groups or salts thereof such as those of animonium hydroxide or the alkali metals, such as scdium and potassium or the I-ike, is applied in the form of an aqueous solution formed without the aid of dispersing agents. One or more of the cationic nitrogen atoms of the poly-cationic nitrogen c(3mpound, being positive in character, is b.-lieved to be adsorbed by the cellulosic fiber of negat;@ve character, and another or others o'L 'Lhe cationic nitrogen aloms is believed to combine with a carboxyl group or possibly a hydroxyl group of the linear polymer so as not only to precipitate the polymer, but also by virttie of the affinity between the fiber and poly-cationic and between poly-cationic and-resin, to anchor the resin to the fiber. VVhen the poly-cationic contains more than two cationic nitrogen atoms, several such atoms may be attracted to the groups on one or more cellulose molecules, and other cationic nilrogen atoms may be attracted to the carboxyl groups of one or more resin mol.-cules. -it has been found that the retention of the resin effected by this bonding or anchoring action is substantially stoichiometric. This results in thorough distribution of the resin among the fibers and prevents irregular "grape bunch" deposition. One type of poly-cationic compounds that may be used for carrying out the iniention are water-soluble subresinous to resinous condensation products, having a moleuclar weight or averag-- molecular weight of 500 to 10,000 or higl-.er,- preferably 600 to 3,000, of polyalkylenepolyaniines -@,v3th poly-functional aliphatic dihalides or halohyd-ins which may or may not be further reacted w-ith urea or with primary urea-formaldehyde condensation products, such as dimethylolurea, the final product being in any evedt water-soluble. Examples of polyfunctional aliphatic compounds are ethylenedichloride, alphadichlorohydrin, dibromohydrin, di-iodohydrin, epichlorchydrin, epibromohydrin, epi-iodohydrin, diepiiodohydrin. The all@ylenepolyamines used in preparing the poly-cationic reaction products er@iployed in practicing our invent;on are well-known compounds corresponding to the formula H2N(C.H2..I-IN).H in which x is one or more. Typical amines of this class are the alkylenediamires such as c',hylc,,nediam@@ne and 1,3-propylenediamine and polyalkylenepolyamines such as diethylenetriamine, triethylenetetrawine, tetraet@qylenepeiitaniine and the corresponding poly-propylenepolyamines and polybutylenepolyamines. The halohydrins are derivatives of glycerol
[2]2,765,228 in -which one terinin-,ll hydroxy group is substituted by a halogen atom; i. e., by c'florine, brow-ine and the like. It has been found that the products wh,.ch they form by reactIon with alkylenez)olyam;nes contain qaaternary ammonium groups, ajd this is probably the reasod "Iihy 5 these products are substantive to cellulose fib@ers. Tl'ic boly-catibl-,ic ype ma be those pod,,icts of ih;s t y disclosed in Yost and A,,iteii U. S. Patent 2,616,874. As disclcsed therein, t@.,-y may be prepired by reacting one mole of a polyamine, and prefe!--ably an alkylene-@-oly- 10 @mine such as ethylenediamine or a pblyal@!-yier@ei3o@YE;.mine such as diethylenetriarnine or tetraefaylenepentariiine with I to 3 moles, preferably 1 to 1.6 moles, of a polyfunctional hal6hyd-rin or aliphatic d'@halide, such as ethyl@ne dichloride d--pending upon the particula-r polyamipe. 15 When the higher proportiois of the polyflinctional hitiohydrin or aliphat-.c dl:halide are ased, froi-.i 1.3 to 9 mgles &r. mole'c@i"i)olyamine, the reaction sholld be carried out- in fWo, three or more sleps or stages with 6n'@y a part of the halohydrin or dihalide present in each siage. 20 B&tween stages, the hydro,-Cn halide is preferably n.-utralized by a base, e. g. sodium hydroxide or -sodium carbon@ite. This reaction is pro.Lerably carried out in an @queous, alcoholic, or aqueous alcoholic solution at temperattires belo,,v the boiling @oint of the mixt,,ire, ustially 25 .@,bout 50' to 70', C. vihen a halolaydri-n is employed, or at femperatiires of about 60' to 1501 C. ,vhen an aliphatic dihalide is-used, in order to permit the use of relati@,ely coi@centrated solutions while ebtaining the product in a hydrophilic or water-dilutable condit-ion. Usual'IY the 30 halohydiin or dihalide is added slow'IY to the polyariine, which is preferably dissolved in water or a water-miscible @olvent such as alcohol, at a rate such that the reactio@i temperature is maintained at the desired temoerature. When a therrrosetti-.i.@ poly-cationic pre-duct ol,' th;s type 35 is desir6d the reaction prod,,ict of the polyamine with the haloh@dri., th.- Ikyl,.c dichloiide or tile like, after the initial exotherrpic react,'@on, ipay be maintained at 60' lo 70' C. until an incre,,ise in viscosity is noted, iiidicating that the second stage of the resin-forming reaction 40 has set in, after which it is cool-ed ai:d diluted with water if necessary to form a stable syrup. In some cases, and particularly where a dihalohydrin is beiiig used, s.ufficient alkdli such as sodium hydroxide, sodium or potassium carbonate, or soditim or potassium phosphate may b,- added before or during the second stage of the reaction to he@,,- 45 tralize thd syrup by combinin,@ with any hydrol-.alide that . . is not taken up by the polyamine. This alkali additio-q also frequently gives improved results when conden@ina polyarbine, of relatively low n-iolecil-lar weight, such as etliylenediamine, diethylenetriamine, or triethylenctetra- r)O mine with several molecular pro-ooi-tions of a monohalohydrin such as epichlorohydrin in the preparation of a therm6setting resin. If desired, the syrup may be subjected to a 'Vacuum distihation after the first stage of the reaction is complet6d to remove any unreacted e,3ichloro- 55 hydrin dichlorohydrin or other Dolyftinctional halohydrin. Anoiher thermosetting type m-ay be prepared by reacting the condensation product of the polyan-iine and a halohydrin or aliphatic dihalide with urea. For example, triethylenetettamine (i - mble) is condensed with ethylene 60 dichloride (I n@(ile) and the resultiilg prod-act -is further cohdensed with 0.6 mole of additional ethyle-,ic dichloride. The resulting product, after removal of water, is condensed ,vith 0.2 to 1.5 mo'.e of urea per -NH- -rbup available, for reaction by fusion -,t 100-200' C., the, pre- 65 ferred range being 120-150' C. until a solution viscosity of B-M is obtained (Gard.,lcr-Holdt on a 50% aqu-lous solution). The resulting condei-isate -m-ay be u-,ed as su--Ii or, if desired, it mi ay be reactell further,@vith forinaldehyde, for example, usin.- 0.6 to 1.5 mole cf forma'@dehyde per 70 hydro.-en on nitrogen atom as d-.Leriph-ied by cz,,Icul.ation from the amounts of polyeL'iylcneDolyamin-- a-iid urv, iised. In this calculation it is assumed that each unreacted -@-NH- group provides one hydroge-Ti ar@d @hctt each rea@ted mol6 of urea provides 2 hydrogeiis. 75 4 Anothcr poly-cationic riiaterial that may be used is polyethylcneimine wnich always co-@ita-ins catio-bic 'gtddp@ either as positively charged ammonium salt groups -CH2CH2N+@q2- or as quaternary ammonium S. The poly-cationic compotinds that may be used include the polymers or copolyi-iiers of styrene, vinyltoluene, or the cumarone-indene class vvhich have been chloroalkylated, such as chloroethylated or chloromethylated, to intro.-d,-,c-, onc chlo@-,oalkyl gr,)up, such as a chloroethyl or chloromethyl group for each I to 5 monomeric tin-.tsjin the polymer, and subsequently quaternized by he@iting with a teriiary amine s,.ich as tritia@thyiarnine, tribthanolamine, dihexylmethylamine, benzyldimethylamine, pyridine. triethvlamine phenyldimethylamine, and so on. The I cornpoi,-nds of this group are par-ticularly valuable because they can be derived from resinous materials of initial low cost, of which the resins of the cumarone-ihddne class are especially importar-,t, and they can be represented geiie@-ally by the folloaing struct-oral formula: R (C H2) @ p -1,T@x RI R2 where P is the residue of the Polymer or coaolymer of the styrene, vinyl toluer,.e a-id cumarone-indene class, n is an integer having values of I to 4 or more but preferably no more than 2, ni has such a value in the preferred group that the compound contains at least one quaternary ammonium group per I to 5 mor@omeric units in the residue P, X is OH, or a negativ,-, salt-forming rad@.cal, such as chlorine, R, RI and R2 are each selected individually from the class consisting of aliphatic (e. g., methyl, 6thyl), alicycl;c (e. g., cyclohexyl), aryl (e. g., phenyl), arylaliphat@c (e. g., benzyl), avd heterocyclic groijps, except that at le'ast two of R, RI and R2 may together constitute with the N atom a h,-terocyclic group. The quaternized polymers of the cumarone-indene class are disclosed and claimed in the application of Earl W. Lane, Serial No. 410,43 1, filed o.1 February 15, 1954 and in the hands of a common assignee. A preferred group of flo.-culai-its because of their colorr less character and tlicir high efficiency are the watersoluble linear polymers (and their quaternaries) of at least 10 mole percent, and preferably at least 50 mole percent (of the total polymerized units therein) of monomeric units having the Formula 1: I -C H2-C RY-A-NEIR2 whete R is H or CT--I3 Y is 0, COO, or CONH A is -C2H4-, -(CH2)3-, Or -i@142CH((@H3)- R' is H, CH3 or C2H5 and R2 is H, CH3 or C2H5 The molecular weights may be from 20 to 20,000 mbnomeric units or even higher. The preferred p(ilyindr -bf this group are those in which Y is COO, R is CH3, A;is - C2F@4-1 R' and R2 are both methyl grc)ups and -the w-olecular weight is at least abolit 100,000 or higher. The qi@atemaries of this preferred grou@ of the compounds may be those obtained by quaternization w-ith a lower alkylene oxide, such as ethylene oyide 'or prdpylene oxide, or any all,.ylating agent,,such as benzyl chloride, methyl chloride r(iethyl sulfate. Any of the water-soluble polymeric amines, or quate rnaries'thereof, that are disclosed in the copending applications in the hands of a comrlon assignee, Serial No. 441,643 filed July 6, 1954; Serial No. 461,285 filed October 81 1954;@and Se-rial NO; 467,872j filed Noveiiiber 9, 1954, may be employed as the -p6ly-@atioiiic-iidi@hbiihg
[3]agent for the water-soluble alkylene oxide condensates used in the present invention. Representative examples include: homopolymers (and copolymers of at least 10 mole percent) of 3-dimethylaminopropyl acrylate, methacrylate, acrylamide or methacrylamide, quaternized with ethylene oxide or propylene oxide, methyl chloride, benzyl chloride or the like; corresponding polymers of diinethylaniinoethyl acrylate, methacrylate, acrylamide, or methacrylamide quatemized with ethylene oxide or propylene oxide, methyl chloride, benzyl chloride or the like; and correspondin.- polymers of diinethylaminoethyl vin-YI ether or of dimethylaminopropyl vinyl ether quatemized with ethylene oxide or propylene oxide, methyl chloride, benzyl chloride or the like. T'he synthetic linear polymer that is to be anchored to the fibers of the products include the condensates of lower alkylene oxides with polymers of acrylic acid, metbacrylic acid and itaconic acid, having average molecular weights of 1,000 to 300,000 or higher. Homopolymers of these acids and copolymers thereof containing at leas,, 35 molar percent of one or more of these acids as the substituent monomer units may be condensed with the ethylene oxide,. propylene oxide, or mixtures thereof. It is preferred to employ homopolymers or copolymers containing at least 50 mole percent of one or more of thes-. acids so that the alkylene oxide condensates of the polymer are readily soluble in water. Other polymerizable com-oounds containing a single vinylidene group that may be copolymerized with one or more of the acids above or with salts of such acids inelude the following esters of acrylic acid or methacrylic acid and monohydric alcohols such as methyl, ethyl, butyl, oetyl, dodecyl, cyclohexyl, cyanoethyl, aminoethyl, and the like; esters of itaconic acid and the above alcohols; esters from maleic, fumaric or citraconic acids, and the above alcohols; vinyl esters of carboxylic acids such as acetic, propionic, butyric, and the like; vinylo-yalkyl esters such as vinyloxvethyl acetate, etc.; vinyl ethers such as ethyl vinyl ether, butyl vinyl ether, octyl vinyl ether, hydroxyethyl vinyl ether, aminoethyl vinyl ether, aminopropyl vinyl ether, dimethylaminoethyl vinyl ether, vinylo.xyethox37ethano'l, vinvioxypropoxyethanol; methacrylonitrile or acrylonitrile; acrylamide, or methaerylamide, and N-substituted amides of these types; vinyl chloride, vinyl bromide, vinyliden-- chloride, vinylidene ffuoride, vinylidene cvanide, 1-chloro-l-fluoroethylene, ethylene, styrene, 2-v'mylpyridine, 4-vinylpyridine, 2-methyl-5- vinylpyridine, and st@rene. The carboxvl-contai).i-ing polymer that is to be condensed with alkylene oxide may be made by dissolving a free radical iiaitiator, s,,ich as ammonium or an alkali metal p--rsulfate in water, heating to about 85' to 100' C., then aradually adding the monomeric acid or the mixture of monomers containing at least about 35 mole percent of the monomeric acid while maintaining the temperature in the above range and refluxing any monomer vapor. The initiator is used in an amount of about 0.5 to 3% on the -.,@ieight of monomers. It may be added in portions at intervals instead of all at once as previously menti(>ned ' ihe aqueous solution of the linear polymer thereb y obtained and @containing free -COOH groups is then reacted with the allylene oxide. If desired, a sma]J amount of an acid such as hydrochloric or sulfuric acid or a small amount of an alkaline material, such as NAOH, KOH, or NH40H may be added to accelerate the reaction but such additions are unpecessary. The reaction may be effected at room tew-perature to about 60' C. in about I to 4 hours. NVhen ethylene oxide is used, a closed pressure vessel is convenient for the reaction, the oxide being introdliced continuously or in successive portions as desired. The proportion of alkylene oxide introduced may vary from I mole percent of the carboxyl-containing units -of the polym.-r to 250 mole percent thereol Preferably 6 equivalent to 10 mole percent to 95 mole perceiftt of the carboxyl-containing uniis of the polymer. Partic ularly valuab le resin conde nsates are obtain ed from a copoly mer of a mixtlr e of (a) one or more monomeric esters of acrylic and/or methacr ylic acid and (b) at least 35 mole percent, and prefp-rablv 50 to 100 mole p-- rcent of, monomeri-- acrylic, methacrylic and itaconic acid or mixtures of these acids. The monomeric esters of acrylic and methaeryec acids, which have proven to be 10 most satisfact ory, are the alkyl. esters in which the alkyl gro-,ip one to eight carbon atoms and which are exemt)lif ie@ by the following : methvi, ethyl, npropyl, isopropyl , n-butyl, isobutyl, se.--- butyl, tertbutyl, isoamyl, tertamyl, hexyl, hept@rl, n-octyl, and 2- ethylhex yl acry15 lat.-s and methacr, ,Iates and isomers of thes.-. The tvjo-stage treating process of the present invention nay be knplied to forined fiber products even after drying thereof, but preferab ly before such drying. Whenev er the productforming operatio n involves the handling of a 20 fiber dispersio n or suspensi on, it is preferab le to apply the treatme nt to the fibers while in such a suspensi on. Thus, in paperforming operatio ns, it is preferre d to apply the twosta.ae treatme nt to the aqueous dispersio n of the fibers, such as in the beater, at the Jordan, in the fan pump, in 25 the stuffbox or in the headbox or in any conduit or channel throu,-h which the - .,qber suspensi on must pass in proc-- cding 'rom ore to another of ' h-. devices mention ed. Tile twosta.@e treatme nt may be applied to fiber dispersio ns of any consiste ncy, especiall y including those con30 taning 0.5 to 6% of fiber in copventi onal papermaking prac' ice. if desired, after ititrodtiction of the polycationic icompound and the resin, the fiber dispersion may be dillted to I(Ywer concentrations such as to 0.001 to 0.5% in preparation for the sheeting operation @,vhich may take S5 place on any suitable equipme nt, such as on the wire of a convention al Fctirdrin ier paper machine. The;condensate in preferred instances contains residual free - carboxyl gro,ips unco@- nbined with alkylene oxide. SLich pre,'erred cordensates m. ay be applied to the paper 40 fib@-rs either as the free acid or in the fortn of watersol uble salts such as of ammoni um or of the alkali metals. The amouit of alkylen e oxide coiade nsate deposi ted on the fibrous produc t may be from 0.5 to 2% by weight of the fiber. For most purpos es, a propor tion of about 45 1% condensat e on this basis is - oreferred. For anchorin.- the coidensat e to the fiber, a proportio n of 0.2 to 2% by weight of the fiber, of the poly-cationic nitro-,en comt)ound may be used. The ratio between the condensate and the cationic compourd is in most cas@-s abc)ut ro 1:1, such as from 7:10 to iO:7 but when th,- preferred group of f!occolant s (Foi,iiLq 1) are emoloyed, the proper'tio n of anchoring agent may be rediiced to as low as onefourth of the amount of condensat e with good results. The pH during depositio n, that is at the time of r),5 introdlcti on of the condensat e into the polycationiccomround-treated fiber, may be within the range of 4 to 9.5, but in most cases, it has beeii found that a range of' 7 to 8.5 is qliite si-iitable, and because of the nonacid,.ty of this rarge, it is preferred. The pH may be (;o cortrolled, not only at the point of depositio n as defined hereinabove, but also throlighout the subsequent har@dling of the treated fiber mass, particularly to the point o:L' slieet formation or molding. In the following examples, whch are illustrative of (35 tiie invention, the tercent of ancho'riTi. @ P.@ent and of ccndensat e are bqs.-d 'en the weight of the fiber; tiae strengths @,"VeTi are all based on a dry product conditioned over a per-.od of at least twelve hours at 50% relative humidity at a temperatu re of about 75' F.; the burst strength 70 (Mullen) is in lbs./sq. in.; the edge tear is in lbs.; the tensile strength is in pounds per square inch. Example I To a bleached sulfite pulp having a consis*ency of 1% the amount of alkylene oxide reacted with the polymer is 75 dry fiber and lightly beaten to a Canadian Standard free-
[4]7 n sof 615@:nil. there is added in an amount of 1%:on es the dry weight of puld a cationic anchoring agent obtained by the condensation of diethylenetriamine with 1.88 moles of ethylenedichloride effected in three stages a@ follows: ,e 'In the frst sta@ , diethylet -ietriamine (1 mole) was heated to about 105' C. and 0.7 mole Oll ethyienedichloride was added while the temperatlire was kept at 105' to 110' C. 'Ihe mixture was heated to 1201 C. and held at this temperature uiatil the viscosity of P sample diluted with water in a ratio of 21.1 was betweep D@aiid E (25' C.) on the Gardner-Holdt scale. The mixture was cooled, and 50% aqueous NAOH added to destroy hydrohal:de. The m-ixture was then heated to 105' C. and 0.6 mo "ie-ethyle,iedichlo-ide added wh;le the temperatiire was kept between 105' lnd 110' C. Th-mixture was heated at 112' C. u-@itil the prod-,ict had a viscosity of W to W+ (Gardner-Foldt). it was then cooled to 100' C., and hydrohalides neutralized by addition of 50% aqueous N;@0H. The reaction inixture was a.-ain@ heated to 105' to 110' C; and 0.58 @nole ethyle@-edichloride added over a 2.5 hour period. Follriwing this, the mixture was beated at 112' C. und@-r rei9ux until the viscosity of the mixtlire (salt first removed by centrifuging) w,-.s abolit X (,Ga;7dner---Llcidt). Th-, product was cooled@and treated with 50% aqueous NAOH to liberate generated hydrohalide. Then 1% of the reaction product of propylene oxide on polyacrylic acid (about 0.6 mole of the oxide per acid unit) having an av,-rage molecular weigh, of around 50,000 is added. The mixture is sheeted on the papermaking wire or screen and dried at about 200' F. in about 2 minutes. The paper had a weight of 40 lbs. per ream. The iinished treited paper and a control sheet obtained in the same way but without the anchorin.a agent and polyacrylic acid derivative had the followin.propi@rties. Dry Dry Edgo MTT Paper Burst Tengile Teir Fold lztroi2gth Strengtb Strength No. Treated ---------------------- 24 16 4.0 57 Control ---------------------- 12 11 3. 4 9 - Example 2 -The procedure of Eyample I was repeated with the same anchoring agent but t@le alkylene ox@.de condensate was replaced with the reaction p@-oduc@ of polymethacrylic acid with about ')O mole p-.rcent of prc@,oylene oxide (that is 0.5 mole of propylene oxide per acidcontaining unit of the polymer). D Ig Dry Edge MIT ilaper B t TI.Iii Tear Fold Sltrength Strengt.@h Stren,@th No. Treated ---------------------- 22 14 I., 26 Control ---------------------- 9 8 2.5 4 E,rample 3 The proc,-dtire of Example I was follow.-d excei)t the water-soluble condensate was obtained by reacting a 1: 1 molar ethyl acry'late: methaeryl@c acid copolymer w@@th 0.6 n@o'@e of ethylene oxide per -COI,-,Hcoitair@;rg polymer unit. !,Iry Dry F(Ig@, MIT Paper Bu,,,t Toiasile Te,@r Fold Strergth @'trcn,,,th Strength No. Finished ----- 18 11 3.9 23 ---------------- Control ---------------------- 8 7 2.8 3 8 @,Examp @4 'The Procddure Of @Example I was'f6llowed except'that the water-soluble alkylene oxide condensate used was replac6d with the condensate obtained by reacting a m copolv er of 40 mole p.-rcent of methyl rnethacryl@te with 60 mole-percent of methacrylic acid and 0 '6 - mole of propylene oxide percarboxyl-cori-laining unit of the polymer. 10 Dry Dry Edge MIT Paper Burst Ten,,ilp Tear Fold Strength Strength Streiigth No. - rinished --------------------- 21 @ll 30 15 ("troi ---------------------- 8 7 2'8 3 Example 5 The procedtire 6f-Example I was followed except that 20 the water-soltible alkylene oxide condensate was replaced with the reaction product of a cqoolymer of 25 mole percent methyl acrylate with 75 m6le percent of ac,rylic acid and 0.63 m6le of propylene oxide per carboxylcentaining unit. '2 Dry Dry Edge @ilIT Paper Burst @Tenqile Tear Fold Strength Strength Strength No. 30 Finished --------------------- 24 13 4. 5 46 Control ------------------ 8 7 2.8 3 Example 6 3,5 The procedure of Example I was repeated except that the water-soluble alkylene oxide condensate was replaced with the reaction product of a copolymer of 50 mole percent of ethyl acrylate with a mixture of 25 n@ ole percentmethacrylic acid with 25 mole percent of acrylic 4( acid and 2.5 -moes of propyl-,ne oxide per carboxylC ontaining unit. Dr Dry Edge MIT y Paper Burst Tensile Tear Fold 45 Strength Strength Strength No. Finisbed --------------------- 17 10 3.6 17 Control --------- ------------ @8 7 2; 8 3 50 .Example 7 The, procedure of Exarnple 2 was repeated except that the anchoring agent and the watersoluble propylene oxide coiidensate were each used in amounts of 2% on the 65 weight of the 'dry pul@. Dry Dry Edge MIT Paper Burst Tensile Tear Fold Streiagth Strength Strength NO. (;o Finished --------------------- 28 19 3. 0 .114 Control ------- -------------- 8 9 3.2 3 Example 8 65 The proc6dure of-Example 1 was followed except that the viater-solub.'te alkylene oxide condensate was replaced Nvith 0.5 percent of a propylene oxide condensate with polymethacrylic acid in which 0.5 mole of propylene, oxidelwas reacted-for each carboxyl-containing unit and 70 the anchoririg agent was replaced with 0.5%, of a homopolymer of dimethylaminoethyl methaerylate quatemized with ethylene oxide to @ the extent of about 85% of the amine-containing groups in @the polymer. The molecular weight of the anchoring agent was, on the order of 75 900,000- to- 300,000.
[5]9 Dry idry Edge MI T Paper Burst Tensile Tea r Fold Strength Strength Strength No. Finished 24 16 3.0 70 9 8 3.0 3 Example 9 To an unbleached kraft pulp having a consistency of 1% dry fiber and lightly beaten to a Canadian Standard freeness of 680 ml. there is added 1% on the dry weight of pulp of a homopolymer of dimethylaminoethyl methacrylate. Then 1% of the reaction product of polymethacrylic acid with 0.5 mole ol' propylene oxide per carboxyl-containing units of the polymer was added. Dry Dry Edge MIT Paper Burst Tensile Tear Fold Strength Strength StreDgth No. Finished --------------------- 37 19 3.9 533 Control ---------------------- 13 11 4.0 9 Example I 0 To a bleached sulfite pulp having a consistency of 1% dry fiber and lightly beaten to a Canadian Standard freeness of about 615 ml. there is added 0.25% by weight, on the weight of the dry pulp, of a polymer of dimethylaminoethyl methaerylate. Then there was added 1% by weight, on the weight of the dry fiber of the reaction product of polymethacrylic acid with 0.5 mole of propylene oxide per carboxyl unit of the polymer. The treatment is adapted to improve the dry strengths of aH types of fiber stocks, especially those of poor quality, such as of oak, poplar, and yellow birch, and those of extremely short fiber length, as well as those of Ion-. fiber length and of good quaety derivation, such as from spruce and hemlock. Any fibrous cellulosic material (capable of adsorbing cationic polyamine/halohydrin resin from an aqueous solution thereof) may be coated ot impregnated by the process of the invention. A wide variety of fibrous cehulosic material used in the preparation of paper, board, moulded resin fillers and the like may be used, such as kraft pulp, rag pulp, soda, sulfate, ground-wood, sulfite pulp and alpha pulp. Similarly, other forms of fibrous cellulose such as cotton linters, and the like may be employed. These materials may be used alone or in admixture with fibers from other sources,. such as jute, hemp, sisal, strin-s, chopped canvas, and other material, either cellulosic or noncehulosic, that may improve the impact resistance, mechanical strength or other properties of the formed or moulded impregnated material. The process of the present invention is adapted to produce papers and other fibrous products having increased strengths. The papers and felts obtained may be used for making paperboards, paper bags of the single waR or multi wall type, backings for flooring such az- linoleum, roofing felts, waterproof or moisture-vaporproof paper, paper or board containers or cartons for milk, butter, foods, etc., resin-impregnated laminatin.@ paper, abrasives r-omposed of resin-impregnated paper coated with abrasive particles, moulded articles, premoulded articles, electrical insulators, filter paper, beatinsulating paper, or loose masses of unfelted and unmoulded impregnated cellulose stock used for air filters, dust filters, heat-insulation and the like. As pointed out above, the poly-cationic compound ccntrols the distribution on deposition of the resin, assuring substantiafly uniform and thorough distribution while avoiding irregular, objectionable, "grape-bunch" effects that would occur with alum or the like. In addition, the condensates are anchored by direct affinity between carboxyl and/or hydroxyl groups therein and the cationic nuclei in the anchoring agent which, in tum, 10 is anchored to thd cellulosic fibers by other cationic nuclei. The adsorption or affinity of the condensate relative to the anchor minimizes the amount of resin lost in the "white water" drained during sheet operations. The condensates of the present invention also impart no Pppreciable increase in wet strength, which allows recovery of "broke." It is to be understood that changes and variations may be made without departing - 'Lrom the spirit and scope 10 of the invention as defined in the appended claims.
