US 2658828 A
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Patented Nov. 10, 1953 PROCESS OF COMBINING SYNTHETIC RESINS AND OTHER MATERIALS WITH CELLULOSE Donald K. Pattilloch, New York, N. Y., assignor to Ohemloch Corporation, Springfield, Mass., a corporation of Massachusetts No Drawing. Application September 15, 1948, Serial No. 49,465
3 Claims. (01. 92-21) I This invention relates to the making of webs of cellulosic fibres, notably paper, paper board, and similar paper products by conventional paper-making procedures, as typified by the conventional single and multi-cylinder, Fourdrinier, Yankee, Harper and Wet machines.
The primary object of the invention is to incorporate With the cellulosic fibres which make up the stock for the production of the paper materials, thermoplastic or thermosetting resins or mixtures thereof.
While various methods have been suggested heretofore, the industry, to a large extent, still resorts to impregnating the preformed web, as distinguished from incorporating the resins with the stock prior to web formation. The reason for this is that when the resin is incorporated with the stock a number of problems arise in connection with the paper-making operation, the most important of which is the difficulty of preventing coagulation of the resin and the consequent sticking to the paper-making wire, felts, clothing, pressing and drying cylinders, i. e., preventing coagulation out in the liquid phase.
I have discovered that the difficulties heretofore encountered may be readily overcome by a simple procedure which does not interfere with or add substantially to the usual operations in the paper mill. According to my discovery, the mechanically treated paper fibres, e. g., in the beater, are pretreated with a cationic surface active agent in an amount which will render the fibres cationically active but not substantially in excess of such amount.
Further, I have found that it is necessary to treat the pretreated, i. e., cationic fibres, with a water soluble salt of a trivalent metal in order to obtain substantially complete pick-up of the subsequently added resin. The amount of the salt which is introduced to the pretreated fibres is critical, the amount of said salt being not greater than an amount which will be completely exhausted on the cationic active fibres. In this connection, in the event there were excess cationic surface active agent present in the aqueous phase, the effectiveness of the metallic salt would be reduced in that part of the same would necessarily be dissipated in neutralizing the free cationic surface active agent. It is to be understood, of course, that both the cationic surface active agent and the metallic salt are of a type which may neutralize each other.
An essential feature of the invention, a will be appreciated from the foregoing, is the sequence in which the cationic surface active agent and the metallic salt are included in the aqueous fibre dispersion. That is to say, the cationic surface active agent must first be included, and thereafter the metallic salt is introduced. If this is not done, it has been my experience that the cationic surface active agent, where the salt has been first added, will simply neutralize the salt, or vice versa, and there will be substantially no resin pick-up when the latter is subsequently introduced.
Aside from the critical sequence of steps, as just pointed out, and the critical amounts of cationic surface active agent and metallic salt which are introduced in such critical sequence, it is highly preferable to introduce the anionic resin dispersion at the point after the mechanical treatment of the paper fibres has been completed and just prior to the flow of the paper stock to the web-forming wire or device. In other words, whether the mechanical working of the fibres is accomplished by jordaning, beating, hy dropulping, or hydrofining or a combination of these operations, the introduction of the cationic surface active agent and the metallic salt is accomplished either during or after such mechanical working, and the anionic resin dispersion is introduced after such mechanical working, preferably at a point immediately before the stock is flowed to the paper-making wire.
The cellulosic felted Web obtained by carrying out this invention before the same has been heated to flow and set the resin, can be readily identified by the presence of substantially all of the resin added on or in the individual fibres. In other Words, such a web, prior tothe flowing and setting of the resin, is to be distinguished from impregnated webs which characteristically will collect or entrap increased amounts of resin in the voids between adjacent fibres.
A distinction between the web produced by this invention and the saturated or impregnated webs, is that when webs of the present invention are laminated under heat and pressure there is substantially no exudation of the resin from the laminated structure. On the other hand, as well known, when impregnated or saturated webs are laminated, one of the great problems has been the extrusion of the resin from the laminated structure which is very observable along the edges of the same. 'This latter situation i due, of course, to the fact that the resin introduced into the preformed sheets finds its way into the voids therein and under pressure it necessarily is expressed from said voids and from the sheets. With the webs produced according to the present invention where substantially all of the resin incorporated with the aqueous disperscn of paper stock is integrally bonded to the external and internal surfaces of the individualfibres this very objectionable condition is overcome, and while I do not want to be lim: ited in any way, I believe that the resin forms as an integral sheath upon the surfaces of the fibres. As will be appreciated, the'extent of the integral coating of the fibres will depend upon the amount of mechanical worlgingand, therefore, the area of fibre surfacewhich is exposed for contact with the resin.
Paper products made according to this invention have a multiplicity of uses, notably, for the production of special papers, bag papers, high wet strength papers, artificial leather or textile replacements for both fabric or spun and twisted threads; the productiohof floor coverings, the pmautuon'or di-electric material; the production'of waterproof backing materials; the production ofoil-resistant gasket materials; the production of inner soling and middle soling for shoes; the production of overlay materials for plywood manufacture; the production of base material for structure uses such as table tops, wall panelling and furniture; the production of tiling, convolute piping,'insulation panels and many other purposes in which the cellulosicplastic complexes, either as single webs or laminated structures, are advantageous.
' It is to be understood that the invention includes not only the concept of incorporating relatively large amounts of resinous material with the cellulosic fibres, whereby to produce products of the types hereinabove described, but also includes the concept of incorporating relatively smaller amounts of resinous material with the cellulosic fibres'for. the production of papers having special properties, e. g., enhanced wet st en et As will be later set forth more particularly, the'invention is useful in connection with various and innumerable types of fibres and pulps, cationic agents, water soluble salts of trivalent z'netals and resins. Therefore, it is not possible to specifically recite the proportions of these various "constituents which would be utilized in producing products such as those above-described.
"One of the great advantages of the present invention lies in the fact that its use is not re stricted to any particular resin or group of resins s'inc'e'I have found that substantially all of those commercially available can be successfully employed. As i well known, only a relatively few resins will lend themselves to saturation or impregnation of preformed cellulosic fibres. Also, by reason of the present invention, it is much easier to control uniform distribution of resin through the fibrous structure and the amount t ere n the we It is well known that in the ir npregnation or saturation of preformed webs the caliper of the paper base must be relatively low in order to get the desired resin incorporation. In fact, it has been called to my attention that present-day impregnation or saturation methods do not permit the successful use of sheets of greater caliper than from 9 to 11 points. The present invention has been successfully employed in sheets having a thickness of from about .030 to .050, i. e., 30 to, 50 points.
4 The invention has been successfully demonstrated by as many as fifty experimental runs, of which the following example is illustrative:
EXA PL I Five hundred and forty pounds of oven dry, unbleached Swedish kraft pulp Kemi-grade were furnished to the beater with 1850 gallons of water, the beater stock then having a consistency of 3.50% bone dry. The initial freeness of the stock on the Canadian Green standard was 770. The pulp was beaten with a normal roll action to a finished freeness of 500 Canadian Green standard.
The stock was suitably tested as by titration to determine the amount of cationic surface activeagent which it could exhaust. This test revealed that theoretically 9% of the cationic surface active agent, based on the dry weight of the pulp, could be included. However, in the interest of safety, and to assure that there would be no possibility of an excess amount of cationic surface active agent being present in the liquid phase where it might coagulate the subsequently added resin, I have found it desirable to use about 2% less than that which theoretically could be included. In the present run exactly 7% of a cationic surface active agent" is employed, the same being an ionizable compound which, upon ionization, gives a wateresoluble anion and a larger waterfinsoluble organic cation. That is to say, it is a polar substance having a positively charged water-soluble portion and a more or less complex water-insoluble surtace active portion which usually is or in.- cludes a relatively long alkyl chain. The specific substance used in this example is a cationically acting wetting agent or cationic surfaceactive agent comprising reaction products of mono.- amyl' amine with an acid serich mixture of oxidized hydrocarbons derived from 36 to 40 Be. fuel oil by controlled liquid phase oxidation of the latter, said mixture having an acid num-, ber from about 118 to about and containing a substantial proportion (one-half or more) of aliphatic carboxylic acids ranging from Cm to C15 (average C12) in aliphatic chain length. The process by which the acids mixture was derived, and by which the amine reaction products were produced therefrom, is generally described in United States Patents Nos. 2,330,524 and 2,330,525.
The beater roll was raised from the bed plate and the treating cycle with cationic surface active agent continued for one hour. At the con,- clusion of this treating cycle exactly 5.5% of paper makers alum in an approximate 5% solids aqueous solution was added to the beater, and after a five to ten minute contact period the treated pulp was pumped to the paper machine chest preparatory to flowing to the paperforming wire.
The amount of alum to be added was determined in the same manner as in the case of the cationic surface active agent, and in the present run the titration indicated that 5.7%, based on the dry weight of the pulp, could be added, and I, therefore, in the interest of preventing coagulation, added a slightly less amount, as indicated. The stock was pumped to the machine chest of a standard Fourdrinier machine.
The activated stock from the beater prepa:
ration was first run over the paper machine to establish a base for operation:
Machine speed, 20 F. P. M.
Machine deckle, 20 inches Machine suction, normal Machine pressing action, normal Sheet weight 120 24x36, 500 (sheets) Oven dry consistency machine head box, 2.23 Freeness factor machine head box, 480 cc. Production, 88# per hour Operation troubles, none Having established the above base conditions for operation, an aqueous dispersion of plasticized polystyrene resin made up on the basis of 5% plastic solids was added to the treated stock at the machine head box through a me tering device without changing the operating conditions on the machine wire. The amount of resin solids added was equal to about 100% Of the weight of the cellulose fibres. The approximate contact time of the treated stock and the plasticized polystyrene resin dispersion in the head box was ten seconds. Upon the addition of the plasticized polystyrene resin to the stock, a complete pick-up of the resin on the fibre was observed. There was no evidence of co-.
agulation or flocculation of the resin and no evidence either in the plastic-cellulose mixture in the wet web, in the supernatant water on the machine wire and in the white water draining from the machine wire of any particles of coagulated or flocculated material.
There was no sticking at any point on the machine wire, on the machine press rolls, on the machine felts, or on the machine dryers. The machine run was of five hours duration from 12:00 noon to 5:00 p. m. The exact conditions of this run are as below:
Machine speed, 20 F. P. M.
Machine deckle, 20 inches Machine suction, normal Machine pressing action, normal Sheet weight 24x36, 500 238# Sheet gauge, 20.5 to 21.0
Oven dry consistency flow box, 0.814% Stock freeness flow box, 475 cc. Production per hour, 173# Reels #4, #5, #6 made on this run Oven dry consistency head box, 2.16% to 2.41 Sticking tendencies, none Foaming troubles, none Operating troubles, none Samples of this product whichwere made under normal machine operating conditions were subsequently laminated under commercial conditions to give a satisfactory laminate.
As stated above, about fifty successful experimental runs similar to the above have been made using various pulps, cationic agents, metal salts and resinous materials.
EXAMPLE II(A) The pulp used as starting material in this machine run was a bleached, Finnish kraft pulp, 100 parts (dry weight) thereof were beaten, in water, in a 100-pound experimental beating engine, operated so as to give a medium to hard beater roll action, for 1% hours to a slowness of 450 cc. (Canadian Green) at a beater consistency of 3.29% (oven dry).
Thereupon, 5 parts by weight of the cationic surface active agent used in the run of Example I were added to the beaten pulp, the same technique of addition and mixing being observed in this step as was observed in the corresponding pretreating step of Example I. After the one hour of circulation of the pretreated stock there was added 5 parts of alum in the form of a concentrated aqueous solution of that salt. The fiber completely exhausted the alum from the liquid phase after a few minutes circulation of the stock in the beating engine. Then, the treated, or activated, stock was pumped to the machine chest and there stored over night (approximately 16 hours). Thereupon, to the stock was added 5 parts by weight of a negatively charged aqueous emulsion or dispersion of a water-soluble (actually, readily waterdispersible) urea-formaldehyde resinous condensation product, and the stock was well agitated to effect homogeneous dispersion of the resin emulsion with the fibers.
A portion of this resin emulsion-treated stock was then diluted and run over the Fourdrinier wire. The machine data follow:
Machine speed, 20.5 F. P. M.
Machine deckle, 19.5 inches Oven dry mixing box consistency, 2.41 Mixing box freeness, 430 cc.
Sheet weight 53# 24x36, 500
Sheet gauge, 5
Production per hour, 36#
The product was a well formed paper sheet devoid of visible particles of coagulated or flocculated resin.
EXAMPLE II(B) To the portion of resin emulsion-treated stock remaining from the machine run recited in Example II(A) there was added a further amount of the same resin emulsion suiiicient to yield a paper product containing 15% resin based on the dry weight of the fiber content thereof, and the stock was again made homogeneous by mixing.
The resulting stock was then formed into a paper web on the Fourdrinier machine in the same manner as that recited in Example II(A) above. No mechanical or operating difiiculties were encountered. No visible particles of coagulated or fluocculated resin were formed, nor was there any evidence of sticking or dirtying of the paper machine parts.
EXAMPLE III The pulp used in this machine run was a special grade of dry Ontario unbleached sulfite pulp, similar to that used in the manufacture of some grades of glassine papers. The pulp is classified as a hard, tough, sulfite pulp. One hundred pounds (oven dry basis) of the pulp were beaten, in water, in a l00-pound experimental beating engine operated so as to give a hard roll action, for about 4.5 hours to a stock slowness of cc. (Canadian Green standard). It was intended to prepare a stock closely approaching a glassine stock in characteristics, but as beating continued it was found that the beater tackle was much too sharp to duplicate the rubbing action, characteristic of glassine stock preparation, and that the stock was becoming increasingly shorter with decreasing freeness. The stock so prepared can be considered an abnormally hard beaten stock, closely approaching glassine in its freeness factor. The beater consistency (oven dry) was 3.5%, and the stock had a pI-I of 6.8. The pH of the mill water was 7.8.
" Although the activating chemical demand of the beaten pulp was determined, by electrometric titration, to be about 9.6% there was added and mixed with the pulp, by the technique described in Example I, only of the cationic surface active wetting agent recited in Example I, the reduction in the amount of pretreating agent being occasioned by the fact that a comparatively small amount of resin was, in this case, to be incorporated and fixed on the P p The alum demand of the so-pretreated pulp was determined to be about 5 To the pretreated stock in the beater there was added an aqueous solution of alum in an amount corresponding to 5 pounds of the salt, and, after about 10 minutes further circulation of the stock, there was also added to the contents of the beating engine a negatively charged, dilute soluble urea-formaldehyde resinous condensation product. After the stock was further circulated for a few minutes to efiect homogeneous dispersion of the resin composition therethrough, the latter was pumped to the machine chest, and (after dilution to about 0.2% consistency) thence to the mixing box and onto the Fourdrinier wire. No mechanical or operating difiiculties were encountered in producing from this stock a dense, compact, well-formed sheet having the characteristics of an extremely hydrated sheet, similar in many ways to a glassine paper. There was no coagulation or flocculation of resin, no foaming, and no Sticking or dirtying of the machine parts. The machine data were as follows:
Machine speed, 20.5 F. P. M. Machine deckle, inches Machine production per hour, 224"; Sheet weight 32# 24x36, 500 Sheet gauge, 0.027
pI-I machine fiowbox, 4.6
EXAMPLE IV One hundred pounds (bone dry weight) of a bleached sulfate pulp was divided into four portions and the portions were beaten, in water,
in as many experimental beating engines, as follows:
1st portion: 2nd portion: 3rd portion: 4th portion:
45 minutes, slowness 560 minutes, slowness 590 15 minutes, slowness 685 15 minutes, slowness 680 to yield a composite containing fibers of different lengths. The pH of the composite 7.1.
Eight pounds of the aforesaid cationic surface active agent was then added to the beaten pulp and homogeneously dispersed therethrough during protracted. circulation of the pulp suspension. The pH of the so-pretreated pulp was 6.2. Thereupon, 5.33 pounds of paper makers alum, in the form of a concentrated aqueous solution, was added to the pretreated pulp and admixed with the latter. The pH of the alumtreated pulp was 4.5. Finally, there was added to the alum-treated pulp a negatively charged (10%), aqueous dispersion of Wateraqueous dispersion of unplasticized polystyrene resin in an amount to provide pounds of said resin.
The resin-treated pulp thereupon was diluted to machine consistency and formed into a paper web on a Fourdrinier machine, 20 inch deckle, operating at a machine speed of 30 ft/min. The machine slowness at the headbox was 360. No foaming or flocculation of resin was ob served. The web was well formed and free from visible particles of resin. The dry weight of the resin-containing sheet was 200 lbs/ream, the basis weight being 100 lbs/ream. V
The above product laminated well, at 240-250 F. and a pressure of 1500-2000 lbs/sq. in.
In a series of experiments similar to those above described, the following results have been obtained:
EXAMPLE V An experimental beater was furnished with kraft pulp and water, and beaten sufliciently to defiber the pulp. The beaten pulp was electrometrically titrated with a cationic surface active agent to determine its absorption demand. The requisite amount of the previously described cationic surface active agent was added, the beater roll raised, and the stock allowed to oilculate for 60 minutes to efiect a complete exhaustion of the added material. Thereafter the pretreated pulp was electrometrically titrated with an aqueous solution of paper makers alum, and again the absorption demand determined. The required amount of alum, 6%, in solution was added, the beater circulated for approximately 10 minutes to complete the reaction, after which the activated cellulose fibers were in condition for combination with added nega tively charged dispersions or emulsions of plastics.
Step A To a portion of the above conditioned cellulose fibers a water soluble phenol-formaldc= hyde condensation product was added, in an amount to give a l to 1 ratio of cellulose and plastic solids, and a sheet made from the mixture.
The sheet formed well, with no indication of sticking to or dirtying of the forming wire, the felts, or the drying cylinder. Examination of the sheet stock under the microscope showed no unattached resin particles, no evidence of flocculation or coagulation, the resin particles being attached to the fiber walls. The retention of the plastic was substantially complete.
Step B To another portion of the conditioned cellulose fibers as prepared above an aqueous disper sion of a water soluble urea-formaldehyde resinous condensation product was added, in an amount to give a ratio of 3 parts of resin solids to 1 part of cellulose fiber, or, expressed percentagewise, a 300% addition of resin solids to the fiber base.
The sheet formed well, with no indication of sticking to or dirtying of the forming wire, the felts or the dryer drum. The sheet was placed in a Carver press, and heat and pressure applied to convert the resinous content of the combination. The resulting product was an extremely hard, horny material, almost completely translucent, and having no resemblance to paper. It was very brittle, and hard, as would be expected from the characteristics of the resin employed.
7 Examination of the sheet stock, under the microscope, showed a complete'absence of unattached particles and no evidence of either coagulation or flocculation. The resin: particles were attached to the fibers in a thick sheath, to give a fiber of greatly enlarged dimensions as compared with the untreated fiber. Retention of the added resinous product was substantially complete.
Step C To still another portion of the conditioned cellulose fibers as prepared above there was added, in aqueous dispersion, an emulsified form of a phenol-formaldehyde resinous condensation product prepared by the emulsification of a solid type of phenol-formaldehyde casting resin, the dispersion carrying an anionic charge. The addition of the resin was made to effect a 1 to 1 ratio of resin solids and cellulose fiber. 7 Sheets made from this product formed well, with no indication of sticking to or dirtying of the forming wire, felts or dryer drums. Several of the sheets were placed in a Carver press and laminated with a platen temperature of 325 degrees Fahrenheit, and a pressure on the platens of 1200 pounds per square inch. The press was "blown several times during the pressing cycle to remove excess volatile matter, the platens cooled at the end of a -minute pressing cycle, and the laminate removed. The sheets laminated well. There was no evidence of extrusion from the sheet, and the laminate was homogeneous and non-grainy.
Examination of the sheet stock under the microscope showed no unattached resin particles and no evidence of coagulation or flocculation. The retention of the added resinous material was substantially complete.
Step D To still another portion of the conditioned cellulose fibers as prepared above there was added in aqueous dispersion a water soluble urea-formaldehyde resinous condensation product, the dispersion carrying an anionic charge, in an amount to give a 1 to 1 ratio of resin solids and cellulose fibers.
The sheets made from this product formed well, with no sticking to or dirtying of the forming wire, felts or dryer drum. The finished sheet was extremely hard and tough, and was Water repellent.
Examination of the sheet stock under the microscope showed no unattached resin particles and no evidence of coagulation or flocculation. Retention of the added resinous material was substantially complete.
This product is of value in the fabrication of high strength, high water resistance, corrugated container board, and solid container board. It is also worthy of mention that such a product has great wet rigidity because of the characteristics of the plastic material employed.
Instead of the particular pulp mentioned in the example, any of the following or mixtures thereof may be successfully employed: unbleached Swedish kraft, unbleached northern kraft, unbleached southern kraft from both southern pine and gum-wood, semi-bleached Swedish kraft, semi-bleached northern kraft, semi-bleached southern kraft from southern pine, bleached Swedish kraft, bleached northern kraft and bleached southern kraft from southern pine, unbleached semi-chemical pulp (neutral sulfite bleached and caustic cooked cotton rag stock; bleached and caustic cooked cotton rag stock, cotton linter pulp, unbleached and cooked hempfibres, unbleached and cooked jute fibres, unbleached and cooked caroa fibres, unbleached and cooked bagasse fibres, unbleached and cooked flax fibres, unbleached and cooked manila fibres, unbleached and cooked sisal, mechanical pulp,
both deciduous and coniferous, old newspaper stock not de-inked, old newspaper stock de-inked,
kraft envelope cuttings, kraft corrugated cuttings, No. 1 mixed paper stock, mill wrapper stock, old corrugated stock, envelope cuttings, and box board cuttings, assorted old kraft papers, shoe cuts half stock, alpha pulp, unbleached and caustic cooked cotton linters, strawboard stock, and, in fact, any cellulosic fibre that is capable of being formed into a web on a conventional type of paper-making equipment,
Instead of the particular cationic agent mentioned in the example, any of the following or mixtures thereof may be successfully utilized: lauryl pyridinium bromide; lauryl pyridinium sulfate; lauryl pyridinium chloride; cetyl pyridinium bromide; cetyl pyridinium sulfate; cetyl pyridinium chloride; cetyl pyridinium acetate; diethyl amino ethyl oleyl amido acetate; trimethyl benzyl ammonium chloride; lauryl amide ethyl phosphate, lauryl amido dimethyl sulfate; lauryl amido ethyl sulfate; 1, 2, 3 triamino benzyl acetate, phosphate or chloride; acid salts or tri azine aldehyde condensates as disclosed in United States Patents Nos. 2,345,543, 2,356,718 and 2,350,719; lauryl trimethyl ammonium chloride or bromide; cetyltrimethyl ammonium chloride or bromide; stearyl trimethyl ammonium chloride or bromide; oleyl trimethyl ammonium chloride or bromide; salts of acidic oxygenated hydrocarbons and aliphatic amines as described in United States Patents Nos. 2,330,524 and 2,330,525; hydroxy ethyl ethanol stearamido hydrochloride; diethanol stearamido hydrochloride; fatty acid salt of substituted oxazoline; octyl pyridinium iodide; octyl pyridinium bromide; octyl pyridinium chloride; dodecyl pyridinium bromide; dodecyl pyridinium chloride; toluene azo-phenyl-trimethyl ammonium chloride; diethyl dodecyl sulphonium hydroxide; triethyl dodecyl phosphonium chloride; dipropyl lauryl sulphonium bromide; beta diethyl amino ethyl oleyl amide acetate; beta diethyl amino ethyl oleyl amide hydrochloride; trimethyl ammonium methyl sulfate or amino oleyl ethylene diamine; water-soluble or acid solution soluble compounds of amino cellulose such as chitosan acetate; beta stearamido phenyl trimethylammonium methyl sulfate and a glyoxalidine compound of the formula:
oleyl-C CH t H 2H4OH and salts of the general formulae:
, 11 and:
n H o-o RN/ on X where R=aliphatic or alkyl aryl group and X=halide, sulfate, phosphate, or salt-forming acidic group; and:
o H R| -C PH47N4H X Y where R=aliphatic straight chain X=salt-forming acidic group Y=alkyl group Instead of the paper makers alum, any watersoluble salt of a trivalent metal or mixtures thereof may be employed as long as it contains trivalent metallic ions in combination with chlorides, sulphates, acetates, formates, phosphates, or nitrates which are water-soluble; examples 5 of the metallic ions are chromium, aluminum, nickel, ferric ion and gold.
Instead of polystyrene resin, any of the following resins or mixtures thereof may be incorporated in the stock; negatively charged aqueous emulsions or dispersions in which the resin particles are in the inner phase with the water constituting the outer phase, examples being as follows: phenol formaldehyde, urea formaldehyde, detone aldehyde, and modifica- 5 tions thereof, cresol formaldehyde, resorcinol formaldehyde, alkyds, modified alkyds, alkyl resins such as alkyl phthalate, polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyril copolymers, acrylic resins and acrylo-nitrile resins, butadiene, butadiene styrene, iso-butyle'ne styrene, maleic anhydride, polyethylene, thiodal, neoprene, GRS type resins, hycar, natural resins including asphalt, vinsol, rosin, natural rubber latex, methyl cellulose, ethyl cellulose, cuma'rone-indene, phenolic varnishes, resin pigment dispersions, polymerized vinylidine chloride and copolymers and numerous others. It is to be understood that these resins ma contain plasticizers which are nonnally combined with individual resins or they may be used in the absence of plasticizers in order to adjust the characteristic formation of the form web.
It will be understood, of course, that after the web is formed it is treated in accordance with customary paper-making practice, namely, pressing, drying and calendering in accordance with conventional practice, and this forms no part of the present invention, For the purpose of flowing and setting the resin, it is subjected to a suitable temperature and pressure recommended for the purpose.
It will'be further understood that the resins may or may not be plasticized with conventional 55 plasticizers, and that they will be introduced as a negatively charged aqueous dispersion in which the resin particles are present in the inner phase and the water constitutes the outer phase.
This application is a continuation-in-part of my copending applications Serial Nos. 531,114, filed April 14, 1944; 536,898, filed May 23, 1944; 570,788, filed December 30, 1944; and 765,490, filed 12 August 1, 1947, all now abandoned, and thedisclosures thereof are hereby incorporated by reference in this application.
I claim: 1. The stepwise process of incorporating sub stantial amounts of thermoplastic and thermo setting resins with cellulosic pulp fibers to the formation of resin-containing paper webs, which consists in pretreating the cellulosic fibers in an aqueous suspension with a cationically active wetting agent which is normally active to coagulate subsequently added resin dispersions, said cationically active wetting agent being an ioniza= ble polar substance having a positively charged water-soluble portion and a larger water -insolwble surface active portion which includes a reia= tively long alkyl chain, the amount of such cationic active wetting agent, from about 5 to about 9.6% by weight based on the dry weight of the cellulosic fibers, being sufficient to render the fibers cationic active but not substantially in excess of such amount, treating the cationic active fibers in aqueous suspension with a watersoluble salt of a trivalent metal of the group con sisting of the water-soluble chlorides, sulphates, acetates, formates, phosphates and nitrates of chromium, aluminum, nickel, ferric ion and gold, the amount of said salt, from about 5 to about 6% by weight based on the dry weight of the cellulosic fibers, being not greater than an amount which will be completely exhausted on the cationic active fibers, thereafter admixing an aqueous suspension of the so-treated fibers, free from trivalent metal salt in the liquid phase, with a negatively charged aqueous dispersion of the resin, the amount of resin being from 5% to 300% by weight based on the dry weight of the fibers, and forming a paper web from the resulting paper stock.
2. The process defined in claim 1, in which the cationic active wetting agent and the salt are added, stepwise, during mechanical treatment of the cellulosic fibers in aqueous suspension.
3. The process defined in claim 1, in which the resin dispersion is added after mechanical treatment of the cellulosic fibers has been completed.
DONALD K. PAT'IILLOCH.
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,315,675 Trommsdorf Apr. 6, 1943 2,325,302 Britt July 2'7, 1943 2,330,524 Shields Sept. 28, 1943 2,330,525 Shields Sept. 28, 1943 2,338,602 Schur Jan. 4, 1944 2,345,543 Wohnsiedler et al. Mar. 28, 1944 2,350,719 Bright et al. June 6, 1944 2,356,718 Wohnsiedler et al. Aug. 22, 1944 2,369,992 Treacy Feb. 20, 1945. 2,394,009 Pollard 1 Feb. 5, 1946 2,407,376 Maxwell Sept. 10, 1946 2,456,567 Scott Dec. 14, 1948 2,484,315 Scott 11 Oct. 11, 1949 2,492,702 Neub'ert et al. Dec. 27, 1949' 2,563,897 Wilson et al. Aug. 14, 1951