WO1994004752A1 - Acid-to-alkaline papermaking process - Google Patents
Acid-to-alkaline papermaking process Download PDFInfo
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- WO1994004752A1 WO1994004752A1 PCT/US1993/000320 US9300320W WO9404752A1 WO 1994004752 A1 WO1994004752 A1 WO 1994004752A1 US 9300320 W US9300320 W US 9300320W WO 9404752 A1 WO9404752 A1 WO 9404752A1
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Classifications
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- 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
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/63—Inorganic compounds
- D21H17/70—Inorganic compounds forming new compounds in situ, e.g. within the pulp or paper, by chemical reaction with other substances added separately
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- 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
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/03—Non-macromolecular organic compounds
- D21H17/05—Non-macromolecular organic compounds containing elements other than carbon and hydrogen only
- D21H17/07—Nitrogen-containing compounds
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- 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
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/03—Non-macromolecular organic compounds
- D21H17/05—Non-macromolecular organic compounds containing elements other than carbon and hydrogen only
- D21H17/13—Silicon-containing compounds
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- 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
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/63—Inorganic compounds
- D21H17/66—Salts, e.g. alums
Definitions
- This invention relates to a fundamentally new papermakin process, based on a fundamentally new flocculation mechanis different from charge-neutralization or polymer-bridging know in the prior art. Specifically, this invention relates to a process for th manufacture of novel and improved paper, board and other wet laid products from furnishes comprising cellulosic and/or syn thetic fibers, optionally also comprising inorganic and organ ic filler pigments, water-soluble and water-disperse polyme adhesives, color dyes and other adjuvants, treated with com plex functional microgel cements.
- the complex functional microgel cements are synthesize in situ (in the furnish) from transient, chemically reactiv subcolloidal sodium-silico-aluminate or similar hydrosol cross-linked with bivalent and/or multivalent inorganic salts optionally also using organic, cationically active chemica compounds having at least two reactive groups in each molecul as auxiliary (additional) cross-linking agents.
- Paper as a web of cellulosic fibers, is made in princi ple by dewatering aqueous suspensions (furnishes) of partiall crushed (refined) cellulosic fibers on stationary or movin screens and drying the resultant screen residue.
- High-molecular-weight organic cationi polymers are often employed as auxiliary flocculants, i proportions of from 1 to 4 lbs. per ton of furnish solids, t increase the efficiency of solids retention.
- auxiliary flocculants i proportions of from 1 to 4 lbs. per ton of furnish solids, t increase the efficiency of solids retention.
- the alkaline papermaking process whose wet-end chemistry relies upon the use of special func- tional high-molecular-weight polymers (retention aids) , is carried out as a rule at a furnish pH ranging from about 7 to 8, although somewhat higher or lower pH levels are not uncom ⁇ mon.
- the fundamental colloid-chemical mechanism employed for furnish flocculation in the latter process is based on "poly- er bridging," according to which the relatively long macro- molecular chains of the above-mentioned high-molecular-weight polymeric retention aids become attached directly to receptive sites on the surface of cellulosic fibers and/or filler parti ⁇ cles.
- polymer bridging manifested by the "tying" of adjacent particulates with polymer chains, ensem ⁇ bles of flocculated matter are formed which can be retained efficiently on the forming wire of a paper machine.
- the papermaking process of the present invention relie on an instantaneous (for all practical purposes) , indiscrimi nate and complete flocculation of any and all particulate present in papermaking furnishes with the aid of in-sit synthesized multicomponent, functional complex microgel disclosed by the applicant in the co-pending Patent Applica tion Serial No. 07/775,025 ("Functional Complex Microgel with Rapid Formation Kinetics") , Filed October 11, 1991, incorporated herein by reference.
- the complex microgels i question are synthesized in principle by cross-linking in situ-formed transient, chemically reactive sodium-silico aluminate and similar subcolloidal hydrosols with the aid o bivalent and/or multivalent inorganic salts.
- step (b) flocculating the optimally dispersed particulat components of papermaking furnishes from step (a) instantane ously (for all practical purposes) , indiscriminately and com pletely to retain an equivalent statistically uniform distri bution of furnish particulates in the resultant floes;
- the wet-end chemistr of an "ideal" papermaking proces ⁇ should also provide, in ad dition to the flocculating action, an intrinsic mechanism fo enhancing the resultant paper products' mechanical strength and even for imparting desirable functional properties.
- the wet-en chemistries of the acidic and alkaline papermaking processe of the prior art have, for all practical purposes, none of th above-mentioned "ideal" features which represent but a few o the many attractive and important benefits provided by th versatile papermaking process of the present invention.
- an object of the invention t provide a working description of the wet-end chemistry of th papermaking process under discussion, relying on the use o the complex functional microgel ⁇ disclosed in the co-pendin Patent Application Serial No. 07/775,025 ("Functional Comple Microgels with Rapid Formation Kinetics") , Filed October 11 1991, applicable to a whole spectrum of tasks extending fro laboratory-scale handsheet making up to full-fledged produc tion runs on even the fastest paper machines.
- a still further object of the invention to provid novel approaches to the manufacture of webs readily acceptin (dissipating) both water and organic liquids.
- a yet further object of the invention is to provide nove approaches to the manufacture of cellulosic webs whose dry an wet strengths surpass those attainable with similar webs mad with the aid of the acidic or alkaline papermaking processe of the prior art.
- a still further object of the invention is to provid novel approaches to manufacturing extra-high-strength cellu losic and other wet-laid products from furnishes optionall comprising, besides cellulosic and/or synthetic fibers, one or more of additional ingredients such as synthetic microfibrils, extraneously prepared novel cellulosic microfibrils, novel ultrafine polymer-emulsion adhesives and novel waterborne rub- ber cements.
- a yet further object of the invention is to provide novel approaches for manufacturing ultraopaque paper (with an opacity of at least 98%) for high-resolution, two-sided com ⁇ puter printout and office reproduction.
- a yet further object of the invention is to provide a general blueprint for custom designing novel approaches to the manufacture of a variety of paper, board and other wet-lai products on a paper machine, having better quality and/or being made fa ⁇ ter and more economically than analogous prod- ucts made with the aid of the acidic and alkaline processes of the prior art, as well as to provide novel approaches to mak ⁇ ing entirely new types of paper, board and other wet-laid products whose manufacture was hitherto not feasible with the aid of the technologies and materials known in the prior art.
- the present invention relates to a fundamentally ne acid-to-alkaline process for manufacturing paper, board and other wet-laid products on a paper machine, from aqueous fur ⁇ nishes having a pH of from 4.5 to 12 (the alkaline and near- ⁇ ubalkaline pH range being preferred for practicing the pres ⁇ ent invention) , wherein said process comprises the following steps: (a) blending an aqueous solution of an alkali-metal or quaternary ammonium silicate, and a second aqueous solution of an alkali-metal aluminate and/or alkali-metal zincate, with a paper, board or wet-laid-nonwoven furnish to form in situ transient, chemically reactive subcolloidal hydrosol, wherei each of said solutions is employed in said furnish at a con centration of from 0.01% to 2.0%, by weight; (b) blending an aqueous solution of at lea ⁇ t one cross linking agent selected from the group consist
- cross-linking agent selected from first group consisting of bivalent and multivalen inorganic salts, employed in a proportion of fro 0.4% to 10.0%, by weight, in relation to the tota mass of paper, board or other wet-laid products and, optionally, at lea ⁇ t one auxiliary cross-link ing agent selected from a second group consisting o organic, cationically active chemical compounds hav ing at least two reactive groups in each molecule employed in a proportion of up to 0.5%, by weight in relation to the total mass of paper, board o other wet-laid products, the ratio of said cross linking agents to said chemically reactive, subcol loidal hydrosols being from 1:10 to 10:1.
- the above-mentioned furnishe ⁇ for makin paper, board and other wet-laid product ⁇ optionally compris at least one of the following materials in proportions speci fied below in relation to furnish solids:
- filler pigments up to more than 50%, by weight
- color dyes up to 5.0%, by weight
- thermoplastic adhesives up t 20.0%, by weight
- novel and improved paper, board and other wet-laid prod ucts are manufactured on paper machines from aqueous furnishe comprising cellulosic and/or synthetic fibers, optionally als comprising at least one functional ingredient such as inorgan ic and organic pigments, organic polymer adhesive ⁇ , color dye and other adjuvant ⁇ u ⁇ eful in papermaking, di ⁇ per ⁇ ed and/o dissolved in said furnishes, by flocculating all particulat furnish ingredients instantaneously, indiscriminately and com pletely with the aid of the above-mentioned, in-situ-synthe sized complex functional microgels which, in terms of second ary functions, also contribute (by virtue of their cementin properties) to the dry and wet strengths of the resultan cellulosic or wet-laid nonwoven webs.
- aqueous furnishe comprising cellulosic and/or synthetic fibers
- optionally als comprising at least one functional ingredient such as inorgan ic and organic pigment
- microgel ⁇ microge cement ⁇
- the microgel ⁇ (microge cement ⁇ ) in que ⁇ tion are formed in two distinct process stages a different polymerization mechanism being active in each stage
- two separate reagent solu ⁇ tions are introduced into an aqueous furnish comprising cellu ⁇ losic and/or synthetic fibers, optionally also containing fil ⁇ ler pigments, water-disperse and/or water-soluble adhesives, dyes and other water-disperse and/or water-soluble adjuvants (auxiliary functional materials) .
- One of these reagent solu ⁇ tions contains an alkali-metal or quaternary ammonium sili ⁇ cate, preferably sodium silicate.
- the other reagent solution contains an alkali-metal aluminate and/or alkali-metal zinc- ate, preferably ⁇ odium aluminate.
- An immediately commencing addition polymerization of the above "primary" subcolloidal- hydrosol-forming reagents leads to the formation of sodium- silico-aluminate (zincate) dimers, trimers and higher-rank oligomers.
- These transient, chemically reactive anionic polymer precursors remain, for a limited period, in a very specific state of solution, for which the objectively fitting term "subcolloidal hydrosol ⁇ " ha ⁇ been employed herein.
- an aqueous solution contain ⁇ ing at least one cross-linking agent selected from the group consi ⁇ ting of e ⁇ sentially colorless, bivalent and/or multi- valent salts of calcium, magnesium, barium, aluminum, zinc and zirconium, preferably calcium chloride or nitrate, i ⁇ intro ⁇ quizd into the above-mentioned furnish containing the subcol ⁇ loidal hydrosol formed in the first process stage.
- cross-linking agent selected from the group consi ⁇ ting of e ⁇ sentially colorless, bivalent and/or multi- valent salts of calcium, magnesium, barium, aluminum, zinc and zirconium, preferably calcium chloride or nitrate, i ⁇ intro ⁇ quizd into the above-mentioned furnish containing the subcol ⁇ loidal hydrosol formed in the first process stage.
- the colloidal consequence of synthesizing the complex microgel cements used in practicing the present invention in in- ⁇ itu, in the furni ⁇ h, is an instantaneous, indiscriminate and complete flocculation (coflocculation) of any and all par ⁇ ticulates present in the furnish.
- the tenacity of the evolv ⁇ ing floes can often be enhanced, improving the efficiency of fines retention on the forming wire, by incorporating sma proportions of cationic polyelectrolytes into the solutions the above-mentioned inorganic bivalent and/or multivale cross-linking salts.
- the primary reagents used the fir ⁇ t stage of the process of the formation of the compl microgels i.e., sodium silicate and sodium aluminate (zin ate)
- the subcolloidal sodium- ⁇ ilic aluminate (zincate) hydro ⁇ ol ⁇ which, along with the inorgan cros ⁇ -linking salts, are the factual microgel-forming agent mu ⁇ t be con ⁇ idered as "higher-rank" reagents synthesized situ from the primary, lower-rank reagents, i.e., sodium sil cate and sodium aluminate (zincate) .
- the product ⁇ of ⁇ uch reactio would be merely ⁇ u ⁇ pen ⁇ ion ⁇ , or precipitate ⁇ , of ⁇ olid, mo or less crystalline particles of bico ponent calcium silica and calcium aluminate (zincate) , respectively, but not micr gels, let alone complex microgels which, by definition, mu contain at lea ⁇ t three different chemical building blocks their macromolecular make-up.
- the complex functional microgels used in practicing t present invention are formed virtually instantaneously, t chemical reaction of polycondensation between the above-me tioned low-molecular-weight subcolloidal hydro ⁇ ols and t bivalent and multivalent inorganic salts being estimated occur in less than one microsecond.
- organi polymeric flocculant ⁇ have relatively narrow molecular-weigh di ⁇ tribution ⁇ and are thu ⁇ incapable of ⁇ ati ⁇ fying "acr ⁇ s ⁇ the-board" the highly differentiated flocculation requirement inherent to ⁇ uch pronouncedly heterodi ⁇ per ⁇ e and polydi ⁇ per ⁇ ⁇ ystems a ⁇ the contemporary furni ⁇ hes for making paper an other wet-laid products.
- the complex micro gel ⁇ under di ⁇ cu ⁇ ion po ⁇ ess ⁇ uch an across-the-board (uni versal) flocculating ability in that, being ⁇ ynthesized i situ and growing continuou ⁇ ly from the very ⁇ malle ⁇ t dimen sions, they sweep through an enormously broad molecular-weigh range. It would obviously be impos ⁇ ible to introduce analo gou ⁇ extraneou ⁇ high-molecular-weight polymeric flocculant into a paper (nonwoven) furnish becau ⁇ e of insolubility.
- chemi cal compounds characterized by di ⁇ tinct phy ⁇ ical and colloid chemical propertie ⁇
- ju ⁇ t one or tw of the four simple, ea ⁇ ily available reagents i.e., ⁇ odiu ⁇ ilicate, ⁇ ilicic acid, ⁇ odium aluminate and alum, has ab ⁇ o lutely no precedent in the inorganic chemi ⁇ try.
- colloidal systems are not always formed in reac tions capable of producing sols; they are formed only (under lining added by the applicant) at definite concentrations o the initial substances, at definite order of their mixing an temperature, and when some other condition ⁇ are met.”
- the preferred tran ⁇ ient, chemically reactive ⁇ ubcolloida hydro ⁇ ol ⁇ used in practicing the present invention are solubl ⁇ odium-alumino- ⁇ ilicates which form ⁇ pontaneously when solu tion ⁇ of sodium silicate and sodium aluminate are blended int aqueou ⁇ ⁇ lurrie ⁇ of particulate raw material ⁇ (furnishes) use for the manufacture of cellulo ⁇ ic or wet-laid nonwoven prod uct ⁇ by the papermaking process under discussion.
- dimer ⁇ , trimer ⁇ and higher-rank oligomers evolve sequentially and continuously into very-low-molecular weight sodium-alumino-silicate macromolecule ⁇ of an anioni polyelectrolyte type. Due to the relatively low concentration of the reagent ⁇ employed, but mo ⁇ tly due to the prompt cro ⁇ linking of the transient subcolloidal hydro ⁇ ol ⁇ (terminatin their further molecular growth) , the evolving ⁇ odium-alumino silicate macromolecules are very ⁇ mall, their e ⁇ timated dimen ⁇ ion ⁇ being at mo ⁇ t only ⁇ lightly larger than 1 nm (10 A) .
- Such highly di ⁇ perse sy ⁇ tem ⁇ represent special borderlin solution ⁇ cla ⁇ ified dimen ⁇ ionally above ⁇ olution ⁇ of cry ⁇ tal loid ⁇ ( ⁇ imple molecule ⁇ or ion ⁇ ) , but below colloidal ⁇ olu tion ⁇ , e.g., those of starch, protein or polyacrylamides.
- ⁇ cientifically appropriate term " ⁇ ubcolloidal hydro ⁇ ol ⁇ " ha been systematically used herein in referring to the above ⁇ y ⁇ tem ⁇ , which ⁇ hould be di ⁇ tingui ⁇ hed from aqua ⁇ ol ⁇ (hydro ⁇ ol ⁇ ) of the prior art which are aqueous suspensions of solid par ticles with diameters of from about 5 nm to 100-200 nm.
- colloidal ⁇ y ⁇ tem ⁇ became traditional ly the domain of ultramicro ⁇ copical inve ⁇ tigation ⁇ and thei clas ⁇ ification as "ultramicroscopic," with particle dimen ⁇ ion ranging from 5 nm to 200 nm, still has a great deal of valid ity for most practical applications.
- some les rigorous colloid textbooks still routinely list the colloida dimensions as extending from 1 nm to 500 nm, or even 1000 nm.
- the dimen ⁇ ions of individual molecule ⁇ of ⁇ ome of th above-mentioned material ⁇ are larger than 1 nm (10 A) , con ⁇ idered a ⁇ the conventional upper limit of cry ⁇ talloid par ticles, but smaller than 5 nm (50 A) , considered as a prac tical lower limit for typical colloidal particles. Since th behavior of such sy ⁇ tem ⁇ overlaps the domains of both crystal loid ⁇ and colloid ⁇ , ⁇ ome authors have introduced the rathe artificial term "semicolloids" to deal with these unusua solutions.
- the period of aging nece ⁇ ary to initiate ⁇ uch tran ⁇ formation may extend from less than a second up to sever al days, or even weeks or months, depending on the concentra tion of ⁇ odium ⁇ ilicate and sodium aluminate (zincate) in th reaction medium (furnish) , and i ⁇ manife ⁇ ted by the appearanc of the Tyndall effect.
- tho ⁇ e ⁇ killed in the art th chemical reactivity of the tran ⁇ ient ⁇ ubcolloidal hydro ⁇ ol ⁇ i question, i.e., the ability to form the complex microgels a the foundation of the present invention by a process of chemi cal cross-linking carried out with the aid of bivalent (multi valent) inorganic salt ⁇ , decay ⁇ with the increa ⁇ ing degree o polymerization (aging) .
- the chemical reactivity i ⁇ lo ⁇ t almos completely when the ⁇ olute particles of the above subcolloida hydrosol ⁇ polymerize beyond the ⁇ olubility limit ⁇ transformin into solid colloidal particles of conventional sols.
- the above cro ⁇ -linking can be carried ou within a period ranging from ⁇ everal ⁇ econd ⁇ to a couple o minute ⁇ , counting from the moment the solutions of sodiu silicate and sodium aluminate are added to furnishes fo making paper, board and other wet-laid product ⁇ .
- the primary purpo ⁇ e of the in- ⁇ itu ⁇ ynthe ⁇ ized comple functional microgels under discussion is to induce an instan taneous, indiscriminate and complete flocculation (cofloccula tion) of all di ⁇ per ⁇ e raw material ⁇ pre ⁇ ent in paper, board o wet-laid-nonwoven furni ⁇ he ⁇ .
- Flocculation phenomena play fundamental role in the manufacture of cellulo ⁇ ic and wet-lai nonwoven product ⁇ ; however, the flocculation proce ⁇ e ⁇ u ⁇ e in the acidic and alkaline papermaking proce ⁇ e ⁇ of the prio art are ⁇ low, detrimentally ⁇ elective (rather than indiscrimi nate) and incomplete.
- the ⁇ e proce ⁇ se ⁇ are no well ⁇ uited for the manufacture of advanced paper, board an wet-laid nonwoven product ⁇ (especially at high paper machin speed ⁇ ) that are free of detrimental con ⁇ equence ⁇ of a ⁇ elec tive flocculation and fractionation of furni ⁇ h component according to specie ⁇ and size, manifested in more or les pronounced performance deficiencies of the resultant product ⁇ .
- each di ⁇ per ⁇ e component of a hetero disperse ⁇ ystem has different surface-chemical properties electrical-charge density, dispersion stability, and ⁇ o forth hence, al ⁇ o a different re ⁇ istance to flocculation.
- coar ⁇ e filler fractions e.g., those with an equivalent spher ical diameter larger than 2 ⁇ m
- coar ⁇ e filler fractions are relatively resistant t colloid-chemical flocculation their retention in the web bein affected primarily by mechanical factors ⁇ uch as turbulence, gravitational settling, or filtration.
- the flocculation o intermediate-size fractions is effecte mainly by the neutralization of electrical charges on fille particles and by polymer bridging.
- the ultrafine filler frac tions i.e., those with an equivalent ⁇ pherical diameter ⁇ mal ler than 0.1 ⁇ m, are hardly affected by the flocculation mech ani ⁇ m ⁇ employed in the acidic and alkaline papermaking proce ⁇ ses of the prior art.
- many ultrafine particulate ⁇ such as color dye ⁇ or polymer-emul ⁇ ion adhe ⁇ ive ⁇ , are largel immune to flocculation by alum or organic polymer ⁇ .
- Another detrimental ⁇ ide effect of the slow and selectiv flocculation of heterodisper ⁇ e and polydisperse furni ⁇ h compo nent ⁇ in the acidic and alkaline papermaking proce ⁇ es of th prior art is the formation of aggregates of the undesirabl ⁇ egregated [...fiber/fiber...] or [...filler/filler...] type ⁇ .
- the latter ⁇ egregation in turn, i ⁇ the rea ⁇ on for a reduce retention of filler particle ⁇ on the forming wire, deteriora tion of web-formation quality, and reduction of the optical performance efficacy of filler particle ⁇ retained in the web.
- the slow and selective flocculation is particularly detrimen tal to the optical-performance efficacy of the expensiv titanium dioxide (Ti0 2 ) pigments, which are virtually alway employed in combination with less expensive, low-refractive index extender pigments intended to function as phy ⁇ ica ⁇ pacer ⁇ .
- Ti0 2 titanium dioxide
- the rea ⁇ on for this reduced optical-performanc efficacy of Ti0 2 is that, because of the inefficient (slow an selective) flocculation proce ⁇ ses of the prior art, the pre dominantly formed filler-particle aggregates are of the opti cally inferior [...Ti0 2 /Ti0 2 ...] and [...extender/extender...
- novel and unu ⁇ ual type of paper, board and nonwoven product ⁇ can be prepared fro even the mo ⁇ t exotic, extremely heterodisperse and polydi ⁇ per ⁇ e furnishes, without incurring even a trace of selectivit (fractionation) or incomplete flocculation.
- furni ⁇ hes of th above-mentioned type could not be used in the papermakin proce ⁇ es of the prior art without incurring unacceptabl material losses and operational difficulties, not to mentio potentially di ⁇ astrous ecological con ⁇ equence ⁇ .
- the exotic furni ⁇ he ⁇ under discus ⁇ ion may contain, amon other thing ⁇ , cellulosic fibers; synthetic organic fibers inorganic fibers; reinforcing synthetic microfibrils an extraneously prepared cellulo ⁇ ic microfibrils; magnetic an electroconductive metal powders; mineral as well as plasti filler pigments with particle dimensions ranging from abou 0.1 ⁇ m up to 20 ⁇ m e.s.d.; non-film-forming (nonfu ⁇ ing, o fu ⁇ ing only at elevated temperatures) emulsion polymers wit particles as small a ⁇ 30 nm in diameter; novel ultrafin polymer-e ul ⁇ ion adhesives with particles smaller than 55 n in diameter and glass-transition temperatures ranging betwee -60°C and +20°C; novel waterborne rubber cements; commer cial water-soluble paper adhesive ⁇ ; microparticulate thermo pla ⁇ tic adhe ⁇ ive ⁇ ; color pigments; and carbon black wit particles even ⁇ maller
- th above particulate ⁇ may have relative den ⁇ itie ⁇ ranging fro about 1 g/cm 3 for organic polymer ⁇ up to 4.2 g/cm 3 for titaniu dioxide pigment ⁇ , or yet con ⁇ iderably higher for metal pow der ⁇ , while their ⁇ urface-chemical propertie ⁇ may range fro very hydrophilic to extremely hydrophobic.
- the ⁇ econdary purpose of the complex functional microgel is to provide, by virtue of their inherent cementing proper ties, an increased level of mechanical ⁇ trength to paper, board and wet-laid nonwoven product ⁇ made by the proce ⁇ o the present invention.
- the adhesive action of the ⁇ e microgel can be controlled by both the dosage employed and a purposefu optimization of their chemical composition, much in the sam way as i ⁇ cu ⁇ tomary in optimizing the bonding ⁇ trength o contemporary indu ⁇ trial inorganic cement ⁇ .
- the principal mechanical ⁇ trength is derived fro hydrogen bonds formed between functional group ⁇ exposed at th surface of fibrillated (refined) cellulosic fibers, the actin range of ⁇ uch bond ⁇ extending merely over a di ⁇ tance of a fe of Angstroms.
- a secondary reinforcement of cellulosic web made by the prior-art papermaking processes is presentl obtained with the aid of water- ⁇ oluble polymer ⁇ , main ⁇ tarch, added directly to the papermaking furni ⁇ h.
- any and all inorganic pa ticulates embedded between cellulosic fibers invariably i hibit the formation of clo ⁇ e-range hydrogen bond ⁇ by phy ⁇ ical ly ⁇ eparating the fiber ⁇ , thus weakening the resultant web ⁇
- the microgel part cles must be extremely ⁇ mall (ultrafine) , ⁇ uch a ⁇ are inde obtained with the aid of the high ⁇ hearing force ⁇ u ⁇ ed in ⁇ y the ⁇ izing these microgels, in ⁇ itu, in paper, board and we laid-nonwoven furni ⁇ he ⁇ .
- the ultrafine microg particles must be "strategically" depo ⁇ ited at the very co tact area ⁇ between adjacent fiber ⁇ .
- the microg particle ⁇ mu ⁇ t have an inherent deformability to ⁇ pread in t form of di ⁇ crete, ultrathin layer ⁇ between the adjacent fibe to be cemented.
- the latte adhe ⁇ ive ⁇ encompa ⁇ ing primarily acrylic polymer ⁇ and co polymers, have average particle diameters smaller than 55 n and glas ⁇ -tran ⁇ ition temperature ⁇ (T g ) ranging from -60°C t +20°C.
- T g glas ⁇ -tran ⁇ ition temperature
- poly ⁇ mer-emulsion adhe ⁇ ive ⁇ have found thus far no application as direct furni ⁇ h additive ⁇ in the prior-art acidic and alkalin papermaking proce ⁇ s, since they cannot be acceptably floccu lated (retained with furnish solid ⁇ ) by the latter.
- fine ⁇ t conventional latexe ⁇ , u ⁇ ed a ⁇ wet-end addi tive ⁇ are too coar ⁇ e to provide any mea ⁇ urable interfibe bonding until the relative weight-content of latex in the we exceed ⁇ about 15%.
- commercial latexes are used only to saturate paper or wet-laid nonwoven webs tha have already been preformed.
- the ⁇ e functional characteri ⁇ tic ⁇ ar derived from the microgel ⁇ ' own highly diversified physica and surface-chemical properties, which can be controlled to large extent by a purpo ⁇ eful modification of the microgels chemical composition to ⁇ uit the intended end-u ⁇ e application of the re ⁇ ultant paper or wet-laid nonwoven product ⁇ .
- intrin ⁇ ically ⁇ ized paper can be manufactured i accordance with the pre ⁇ ent invention by incorporating mino proportions of organic, cationically active chemical compound with at least two reactive groups in each molecule into th solution ⁇ of bivalent and multivalent inorganic cro ⁇ -linkin salts.
- the resultant complex microgels made up of hybri macromolecule ⁇ of an inorganic/organic polymer-polyconden ⁇ at type, are inter ⁇ persed throughout the consolidated cellulo ⁇ i web ⁇ in a statistically uniform fashion, providing a ⁇ teri matrix of di ⁇ crete hydrophobic ⁇ ite ⁇ , thus also a controlle level of intrinsic sizing.
- the surface-chemical properties of the resultant webs ca also be modified indirectly with the aid of the complex func tional microgels under discu ⁇ sion, by coflocculating wit other furnish ingredients ⁇ uch powerful ⁇ urface-chemi ⁇ try modifying agents in their own right as polymer-emulsion adhe sive ⁇ (having a dual organophilic/hydrophilic character) organophilic or even hydrophobic organic dye ⁇ , polar minera pigment ⁇ , or organic polymer ⁇ of controlled polarity.
- the principal reagent ⁇ of commercial significance for th synthe ⁇ i ⁇ of the complex (multicomponent) functional microgel u ⁇ ed in practicing the present invention are as follows:
- water- ⁇ oluble e ⁇ entially colorless, bivalent an multivalent ⁇ alt ⁇ of calcium, magnesium, barium, aluminum zinc, and zirconium, preferably calcium chloride or calciu nitrate.
- calcium nitrate alone or in blends wit calcium chloride, i ⁇ beneficial during hot ⁇ ea ⁇ on ⁇ when man paper mill ⁇ encounter problem ⁇ of aggravated bacterial conta mination and ⁇ lime growth.
- the use of aluminum sulfate, alone or in combination with calcium chloride and/or other equivalen cros ⁇ -linking ⁇ alt ⁇ , may be advantageou ⁇ in tho ⁇ e in ⁇ tance ⁇ i which it i ⁇ de ⁇ irable to lower the pH of a flocculated pape furni ⁇ h, particularly one containing groundwood fibers.
- an other common acidifying agents can also be u ⁇ ed for the abov purpo ⁇ e.
- the proportion ⁇ of acidifying agent ⁇ needed to lowe the furni ⁇ h pH to a de ⁇ ired level mu ⁇ t be a ⁇ essed beforehand e.g., by flocculating an aliquot ⁇ ample of the furni ⁇ h with a unadulterated (alkaline) complex microgel and then titratin the resultant flocculated furnish with a solution of the acid ifying agent(s) to be employed.
- the ⁇ e microgels are used a ⁇ a rule only i proportion ⁇ nece ⁇ ary to accomplish the intended tasks.
- microgel content ranging from about 0.4% to 10%, b weight, a ⁇ determined by a ⁇ hing, wa ⁇ found to be adequate fo many type ⁇ of paper, board and wet-laid nonwoven product ⁇
- the preferred microgel contents for most commercial paper board and wet-laid nonwoven products range from about 4% t 10%, by weight, as determined by a ⁇ hing after wa ⁇ hing out th electrolyte byproducts of the cros ⁇ -linking reaction, ⁇ uch a NaCl, NaN0 3 , or Na 2 S0 4 .
- the reagent dosage ⁇ encompa ⁇ ed 3 of ⁇ odium silicate, 3 g of sodium aluminate and 6 g of calci chloride per 100 g of dry furnish mas ⁇ . From the standpoi of both lowering the reagent-consumption requirement ⁇ a attaining better end re ⁇ ult ⁇ , it i ⁇ advantageous to use t highest pos ⁇ ible furni ⁇ h- ⁇ olid ⁇ concentrations, e.g., of up 20% or even 30%, by weight. Furni ⁇ he ⁇ with a ⁇ olid ⁇ conce tration appreciably lower than 2%, by weight, may requi higher microgel dosage ⁇ than those recommended above.
- the acceptable ratio of sodium silicate to sodi aluminate, sodium silicate to sodium zincate, or sodi silicate to the combined mas ⁇ of ⁇ odium aluminate and ⁇ odi zincate employed in forming the above ⁇ ubcolloidal hydro ⁇ o can be varied from 1:10 to 10:1, by weight.
- the preferred concentration of sodium silicate in t furni ⁇ h ranges from 0.01% to 2.0%, by weight, the same ran of concentration ⁇ being preferred with ⁇ odium aluminat ⁇ odium zincate or combination ⁇ thereof.
- concentratio of the above reagent ⁇ in the furni ⁇ h exceed 2%, by weight, accelerated molecular-weight growth of ⁇ odium-silico-alumina (zincate) macro olecules sets in, reducing the latters' chemi cal reactivity toward the inorganic cro ⁇ -linking salts.
- the ratio of calcium chloride or equivalent inorgani cro ⁇ -linking ⁇ alt(s) to the combined mas ⁇ of the tran ⁇ ient chemically reactive ⁇ ubcolloidal hydro ⁇ ol ⁇ to be cross-linke can vary from 1:10 to 10:1, by weight, but the simple ratio o 1:1 wa ⁇ found to be most sati ⁇ factory for ⁇ ynthe ⁇ izing in sit complex functional microgels with adequate flocculating effichee ⁇ and for providing a subsequent marked enhancement o the dry and wet strength of the resultant webs.
- the amount o calcium or equivalent bivalent and multivalent ions present i the reaction medium should optimally exceed by at least 50 the quantity of ⁇ uch ions bound chemically by the above-men tioned transient subcolloidal hydro ⁇ ols.
- the latte organic compounds ⁇ elected from the group comprising cationi surfactant ⁇ , organometallic Werner complexes and cationi polyelectrolytes, ⁇ hould be added in only relatively mino proportion ⁇ to the ⁇ olutions of inorganic cross-linking salt to the extent needed for imparting the de ⁇ ired ⁇ urface-chemi cal modification to the in- ⁇ itu ⁇ ynthesized complex microgels thus indirectly also to the re ⁇ ultant paper, board and wet laid nonwoven products.
- reactive group in each molecule nece ⁇ ary for a particular functional pur po ⁇ e, e.g., ⁇ urface-chemical modification of paper, board o wet-laid nonwoven webs, must be determined empirically fo each individual agent and the intended end-product applica tion, e.g., with the aid of contact angle determinations ⁇ izing te ⁇ t ⁇ , and ⁇ o forth.
- the in-situ formation of complex functional microgel used in practicing the pre ⁇ ent invention i ⁇ practicall independent of the temperature of the reaction medium.
- the above microgels can be formed withi the entire temperature interval in which water remain ⁇ fluid provided that the ⁇ tability of the reagent ⁇ i ⁇ not affected a elevated reaction temperature ⁇ .
- a ⁇ pecial con ⁇ ideration, fo example, ⁇ hould be given to the limited thermal ⁇ tability o ⁇ olution ⁇ of ⁇ odium aluminate.
- a ⁇ et of handsheets wa ⁇ prepared by treating a chemic pulp con ⁇ i ⁇ ting of a 50:50 softwood/hardwood blend with brightnes ⁇ of 86%, u ⁇ ing the previou ⁇ ly de ⁇ cribed in- ⁇ itu (the furni ⁇ h) ⁇ ynthe ⁇ ized calcium- ⁇ ilico-aluminate microgel ⁇ the papermaking (wet-end) chemical ⁇ .
- the hand ⁇ heet ⁇ , havi dimen ⁇ ion ⁇ of 20 cm x 20 cm and a ba ⁇ i ⁇ weight of 60 g/m 2 were prepared with the aid of a ⁇ heet mold, u ⁇ ing a procedu developed specifically for laboratory applications of t papermaking process of the present invention.
- the minibatch of flocculated furnish was transferred fr the blender into a 2-liter beaker and, after an aging peri ranging from a few minutes to about 2 hours, diluted wi water (under stirring) to the full capacity of the beaker a poured into the mold to form a handsheet.
- the wet handsheet were fir ⁇ t pressed to a solid ⁇ level of about 35% and the dried on a rotating heated drum covered with a felt.
- Analogous handsheets were prepared with the aid of a typical acidic paper making proces ⁇ using alum and Percol 292 (a high-molecular weight cationic polyacrylamide flocculant) in proportions 20 lbs. and l lb., respectively, per ton of pulp.
- Some of th control hand ⁇ heet ⁇ were prepared from a furni ⁇ h containin only fiber ⁇ while ⁇ ome additional control hand ⁇ heets were pre pared from the same furnish to which increa ⁇ ing proportion ⁇ o starch were being added.
- the principal handsheet ⁇ were characterized by a vastl better formation quality, significantly higher dry and we strengths as well as stiffne ⁇ , more pronounced “rattle” an ⁇ lightly higher brightne ⁇ and opacity than analogou ⁇ contro hand ⁇ heet ⁇ made without the use of web-strength-reinforcin ⁇ tarch.
- the undersized pigmen fraction ⁇ with particles smaller than about 0.1 ⁇ m e.s.d. ar referred to in the trade a ⁇ ultrafine. or subpigmentary. sinc their inadequate light-scattering efficacy disqualifie ⁇ the as pigments in the conventional (commercial) sen ⁇ e.
- the di ⁇ crete microgel re ⁇ idue ⁇ embedded in the hand ⁇ heet ⁇ are dimen ⁇ ionally yet much ⁇ maller than typical ⁇ ubpigmentar particle ⁇ .
- a ⁇ is well known to those skilled in the art, th principal hand ⁇ heet ⁇ would be automatically brighter by abou 3-4 percentage points and more opaque by about 8-10 percentag points if the microgel residue in the ⁇ heet ⁇ were replace with an equivalent proportion (i.e., 7%, by weight) of a extraneou ⁇ ⁇ ynthetic filler pigment, ⁇ uch a ⁇ precipitate calcium ⁇ ilicate or an in- ⁇ itu (in the furnish) precipitate alumino-silicate filler pigment of the type di ⁇ clo ⁇ ed in U.S Patent No. 2,757,085 to Paquin.
- the wet ⁇ trength of hand ⁇ heet ⁇ wa ⁇ found to b 600% higher with the principal ⁇ ample than with the corre ⁇ ponding control ⁇ ample ⁇ .
- th high-wet- ⁇ trength propertie ⁇ can be imparted to cellulo ⁇ i web ⁇ by the in- ⁇ itu ⁇ ynthe ⁇ ized complex microgel ⁇ only becau ⁇ the di ⁇ crete microgel depo ⁇ it ⁇ , inter ⁇ per ⁇ ed throughout th fibrou ⁇ ⁇ tructure, are both ultrathin. causing no interferenc with the formation of close-range hydrogen bonds betwee cellulosic fibers, and strategically located at the intimat fiber-to-fiber contact areas.
- the only practi cally feasible ways of increasing the dry or wet strength o cellulosic web ⁇ known in the prior art are through the addi tion of organic water- ⁇ oluble "glue ⁇ " to the fiber furni ⁇ h.
- An out ⁇ tanding feature of the papermaking proce ⁇ of th pre ⁇ ent invention inherently related to the in ⁇ tantaneous indiscriminate and complete flocculation mechanism, i ⁇ tha all particulate furni ⁇ h ingredients become coflocculated in stati ⁇ tically o ⁇ t uniform fa ⁇ hion, regardle ⁇ of the ⁇ e parti culate ⁇ ' dimen ⁇ ion ⁇ , morphology, relative densities, surfac chemistry or colloidal characteristic ⁇ .
- particulate ingredient ⁇ contained i heterodi ⁇ per ⁇ e and polydisperse papermaking furni ⁇ he ⁇ , such a cannot be avoided in the papermaking processes of the prio art, i ⁇ , for all practical purposes, totally eliminated in th papermaking proces ⁇ of the pre ⁇ ent invention.
- Th first control batch, designated “AC” (acidic) wa ⁇ dilute right away to a con ⁇ i ⁇ tency of 0.7% and then flocculated i accordance with typical prior-art acidic-papermaking proce dure ⁇ , u ⁇ ing alum and Percol 292 in proportions of 20 lbs.
- the principal batch settled to the bottom of the ja in the form of a ⁇ ingle floe ("monofloc") re ⁇ embling a large fluffy cotton ball ⁇ urrounded by a cry ⁇ tal-clear ⁇ upernatant the monofloc in question being characterized by an extremel uniform micrograin structure.
- monofloc ⁇ ingle floe
- pa per and board are made from very dilute furnishes, containin only about 0.5-0.7%, by weight, of solid matter.
- ⁇ olids concentrations in the furnis could be increa ⁇ ed 2 or 3 time ⁇ abov the cu ⁇ tomary level ⁇ with only minor modification ⁇ of the con temporary headbox de ⁇ ign ⁇ .
- furni ⁇ h con ⁇ i ⁇ tencies e.g., of up to 4 or 5 times higher than those currently u ⁇ ed are likely to be fea ⁇ ible with ⁇ omewhat more radically modi fied headbox de ⁇ ign ⁇ .
- Example II The total coflocculation of cellulosic fibers and minera filler particles by the in-situ ⁇ ynthesized complex microgel is another important finding made in Example II.
- a ⁇ i ⁇ wel known to those skilled in the art, the uniformity of web for mation in the acidic and alkaline papermaking proces ⁇ e ⁇ of th prior art improves with increasing filler-loading levels, u to about 20%, by weight.
- signi ficant proportions of valuable furnish ingredients are sy ⁇ te matically and irretrievably pa ⁇ ed into wa ⁇ te-water ⁇ tream when the acidic or alkaline papermaking proce ⁇ ses of the prio art are employed, cau ⁇ ing ⁇ ub ⁇ tantial material lo ⁇ e ⁇ a ⁇ wel a ⁇ ⁇ eriou ⁇ ecological problem ⁇ .
- the tota (100% complete) flocculation of particulate furni ⁇ h ingre transce ⁇ attained with the aid of the papermaking proce ⁇ s of th present invention enables one to recover 100% of the particu late matter from spent furni ⁇ hes before the latter are pas ⁇ e to wa ⁇ te-water stream ⁇ .
- the complete elimination of particu late contaminant ⁇ from wa ⁇ te-water streams, using filtration cycloning and other easy methods for separating ⁇ olid ⁇ fro liquid ⁇ , provide ⁇ a clear economical and ecological advantag over the papermaking proce ⁇ e ⁇ of the prior art.
- the total coflocculation of fiber ⁇ and filler particle by the in-situ-synthesized complex functional microgels offer the attractive possibility of attaining a true "self-extin guishing" process loop on a paper machine.
- a self-extin guishing loop can be realized preferably by replacing th conventional water- ⁇ oluble ⁇ tarch adhesives in papermakin furnishe ⁇ with particulate (polymer-emul ⁇ ion) adhe ⁇ ive ⁇ an flocculating these furnishes at very-high solid ⁇ , e.g., of u to 10-30%, by weight, with the aid of the in- ⁇ itu synthesize complex functional microgels.
- di ⁇ per ⁇ ant ⁇ e.g., from filler ⁇ and adhe ⁇ ive ⁇
- the rea ⁇ on for the above-mentioned rever ⁇ al of filler retention trend ⁇ is a bette utilization of the fiber fines generated during refining o cellulosic pulps.
- the discrete cellulosic fiber fines gener ated by refining are "short-lived,” reattaching themselve readily to the comparatively much larger full-fledged fiber after a relatively ⁇ hort period of aging, or, particularly during the cour ⁇ e of furni ⁇ h flocculation by the slow an inefficient flocculation mechanism ⁇ of the acidic and alkalin papermaking proce ⁇ e ⁇ of the prior art.
- th latter fiber fine ⁇ contribute little or nothing to reinforcin the re ⁇ ultant fibrou ⁇ network ⁇ or to facilitating the reten tion of filler particle ⁇ .
- fre ⁇ hly refined fibe furni ⁇ hes still containing freely floating, unattached fibe fines
- the in-situ synthe ⁇ ized complex micro gel ⁇ inducing an in ⁇ tantaneou ⁇ flocculation of all particu late ⁇ pre ⁇ ent in the furni ⁇ h
- the numerically abundant fibe fine ⁇ become intricately coflocculated with full-fledge fiber ⁇ , ⁇ ignificantly contributing to the reinforcement of th re ⁇ ultant fibrou ⁇ network ⁇ .
- Paper product ⁇ of th latter type e.g., those having a relative filler content i exces ⁇ of 25%, by weight, are referred to in the trade a "high-a ⁇ h" papers.
- Regardles ⁇ of the obviou ⁇ ecological an economical benefit ⁇ offered by high-ash paper products how ever, tangible technological advances in implementing routin ma ⁇ production of the latter are ⁇ till in the ⁇ tate of rela tive infancy.
- the mo ⁇ t important rea ⁇ ons for the abov apparent lack of succe ⁇ are the exce ⁇ ive deterioration o ⁇ heet ⁇ trength at high level ⁇ of filler loading, relativel high abra ⁇ ivity of the conventional filler pigments, as wel as the deterioration of ⁇ heet-formation quality a ⁇ ociate with the har ⁇ h colloid-chemical mea ⁇ ure ⁇ which mu ⁇ t be under taken to effectively flocculate, retain and affix the ma ⁇ iv proportion ⁇ of filler ⁇ contained in high-a ⁇ h paper ⁇ .
- the ⁇ har ⁇ h measures pertain, most of all, to employing high dosage of polymeric flocculants to obtain an adequate flocculation o filler particles in high-ash furnishes along with employin high proportions of water-soluble adhesives to compensate fo the exces ⁇ ive fiber debonding resulting from high filler loading levels.
- Novel promi ⁇ ing approaches applicable to the manufactur of high-ash paper products have been opened, however, by th papermaking proces ⁇ of the present invention.
- One suc approach is applicable to the manufacture of moderately-high- ash paper, containing up to 25%, by weight, of conventional mineral filler pigments in combination with the novel ultra fine polymer-emulsion adhe ⁇ ive ⁇ di ⁇ cu ⁇ ed previou ⁇ ly.
- the papermaking proce ⁇ s of the present invention is als suitable for manufacturing very-high-ash paper with filler loading levels ranging from 25% to more than 50%, by weight
- the manufacture of the above paper grades require ⁇ , however that both the previou ⁇ ly mentioned novel functional fille pigment ⁇ and ultrafine polymer-emul ⁇ ion adhe ⁇ ive ⁇ be ⁇ imulta neou ⁇ ly employed.
- the fille pigment ⁇ in que ⁇ tion are made in principle by a controlle aggregation of very-fine-particle- ⁇ ize kaolin clay ⁇ (ofte referred to in the trade a ⁇ high-glo ⁇ ing clay ⁇ ) combined wit other functional ingredient ⁇ , such as the novel ultrafin polymer-emulsion adhe ⁇ ive ⁇ , for reducing fiber debonding i paper-filling application ⁇ , and/or with ⁇ ynthetic and/o cellulosic microfibrils, for reducing fiber debonding an increasing filler-retention efficiency.
- the latter fille pigment ⁇ are uniquely qualified for very-high-a ⁇ h fillin application ⁇ in that, among other thing ⁇ , the ⁇ e pigment ⁇ optical-performance efficacy doe ⁇ not decay at even th highe ⁇ t filler-loading level ⁇ and their unu ⁇ ually low abra ⁇ ivity rarely approache ⁇ 0.5 mg on the Einlehner te ⁇ ter.
- the unique ⁇ uitability of the novel ultrafine polymer emul ⁇ ion adhe ⁇ ive ⁇ for the manufacture of high-ash papers ca be understood readily con ⁇ idering that their average particl diameter ⁇ are ⁇ maller than 55 nm.
- the averag particle diameters of the overwhelming majority of polymer emul ⁇ ion adhe ⁇ ives (latexes) used in the paper industry rang from about 150 to 200 nm.
- the averag particle diameters of the overwhelming majority of polymer emul ⁇ ion adhe ⁇ ives (latexes) used in the paper industry rang from about 150 to 200 nm.
- the dimen ⁇ ion ⁇ of the "glue line" (adhe ⁇ ive between two adhint ⁇ ) ⁇ houl be con ⁇ iderably ⁇ maller than the dimen ⁇ ions of the adhint them ⁇ elve ⁇ , particle ⁇ of conventional latexes being as a rul too large to form proper microadhe ⁇ ive joint ⁇ of fiber/fille or filler/filler type ⁇ .
- both commercial latexes an the novel ultrafine polymer-emul ⁇ ion adhe ⁇ ives are totall (100%) flocculated by the in-situ- ⁇ ynthe ⁇ ized complex func tional microgel ⁇ used in practicing the present invention, th use of such adhesives as wet-end additive ⁇ pre ⁇ enting none o the above-mentioned runnability problem ⁇ .
- Ultraopaque printing paper is understood herein as having a opacity of at least 98.0%, necessary to eliminate the dis turbing show-through of high-optical-density laser prints fro the opposite sheet side.
- the ultraopaque, color-coded handsheets under discu ⁇ io were prepared using the procedures and fiber-furnish compo ⁇ ition de ⁇ cribed in Example I, except that Hydraid 777 ( commercial polyelectrolyte retention aid) in a proportion o 0.75 lb ⁇ .
- the furni ⁇ h for makin hand ⁇ heet ⁇ al ⁇ o contained the previou ⁇ ly mentioned ultrafin polymer-emul ⁇ ion adhe ⁇ ive in a proportion of 1.5 g per 100 of furni ⁇ h ⁇ olid ⁇ ; a blue dye (Victoria blue) in a proportio of 0.075 g per 100 g of furni ⁇ h ⁇ olids (equivalent to 2 lbs of dye per ton of furnish ⁇ olids) ; and the previously men tioned aggregate filler pigment, used in ⁇ uch proportion ⁇ a to obtain a filler-loading level of at lea ⁇ t 35%, by weight in the re ⁇ ultant hand ⁇ heet ⁇ .
- furni ⁇ h component ⁇ including the polymer-emul ⁇ io adhe ⁇ ive and dye, were coflocculated uniformly and completel by the in- ⁇ itu- ⁇ ynthe ⁇ ized hybrid inorganic/organic comple microgel ⁇ , the ⁇ upernatant (filtrate) being completely clea and colorle ⁇ .
- the hand ⁇ heet ⁇ had a ba ⁇ i ⁇ weight of 51.9 lb ⁇ per 3000 ft 2 ; a filler-loading level of 35.0%, by weight; a opacity of 98.0%.; a brightne ⁇ of 82.3%; and a lightne ⁇ o 85.0%.
- the hand ⁇ heets had satisfactory strength, handling an rattle, a very light pastel blue color, and a most attractiv ⁇ urface appearance re ⁇ embling that of a coated paper.
- the extra-high opacity of the above very-high-ash hand ⁇ ⁇ heet ⁇ made it po ⁇ ible to print high-optical-density images on both sides, using a la ⁇ er printer, without any print ⁇ how- through from the oppo ⁇ ite side being noticeable.
- the hand ⁇ heet ⁇ were also found to be most suitable for desktop-publi ⁇ hing applica ⁇ tions requiring high-resolution, high-fidelity, high-contra ⁇ t reproduction of delicate halftone ⁇ cale ⁇ .
- a typical low leve of a mineral filler mechanically delaminated clay
- the above brightness reversal can b reduced, or even eliminated, by partially or totally replacin calcium chloride (as the cros ⁇ -linking agent) with alum and/o adding a predetermined proportion of acid to the solution o the cross-linking agent(s) .
- Inten ⁇ ely colored paper ⁇ can al ⁇ o be obtained with th aid of the papermaking proce ⁇ s of the present invention b ⁇ imply increa ⁇ ing the proportion ⁇ of dye ⁇ added to th furni ⁇ h.
- Analogous intensely colored paper ⁇ can not be mad by the acidic or alkaline papermaking processe ⁇ of the prio art without ⁇ evere dye lo ⁇ e ⁇ and the accompanying unavoidabl ⁇ erious contamination of waste-water stream ⁇ .
- th ⁇ evere degradation of ⁇ trength of inten ⁇ ely colored paper mad by the papermaking proce ⁇ e ⁇ of the prior art can be curtaile or even eliminated with the papermaking proce ⁇ of the pre ⁇ en invention by incorporating the highly efficient novel ultra fine polymer-emul ⁇ ion adhe ⁇ ive ⁇ and/or novel waterborne rubbe cement ⁇ into the ⁇ tarting furni ⁇ he ⁇ .
- the opacifying power of carbon blac obtained from ⁇ uch dispersions is about 100-150 times highe than the opacifying power of titanium dioxide.
- An additiona proces ⁇ ing of the commercial carbon-black di ⁇ per ⁇ ion ⁇ with th aid of the ma ⁇ ter-batch method in que ⁇ tion ⁇ till furthe increases the above-mentioned opacifying power by a factor o 20 to 50.
- the former mu ⁇ t be employed in combination with latexe ⁇ o ultrafine polymer-emul ⁇ ion adhe ⁇ ive ⁇ , or with novel waterborn rubber cement ⁇ obtained by underpolymerization of the latte ultrafine emul ⁇ ion adhe ⁇ ive ⁇ .
- the papermaking proce ⁇ of the pre ⁇ ent invention can al ⁇ be u ⁇ ed for the manufacture of very-high-a ⁇ h printing paper with filler-loading level ⁇ approaching or even ⁇ urpa ⁇ ing 50% by weight, while con ⁇ iderably reducing these papers' basi weight and pre ⁇ erving the nece ⁇ ary ⁇ heet ⁇ trength.
- the lat ter ta ⁇ k can be realized by incorporating up to 2%, by weight of ⁇ ynthetic microfibril ⁇ and/or extraneou ⁇ ly prepared nove cellulo ⁇ ic microfibril ⁇ with a length ranging from about 10 ⁇ to 200 ⁇ m in combination with 1-5%, by weight, of the nove ultrafine polymer-emulsion adhesive ⁇ and/or waterborne rubbe cements into furnishe ⁇ for making the above-mentioned very high-ash paper products.
- the novel (extraneou ⁇ ) cellulo ⁇ ic microfibrils should b distingui ⁇ hed from ordinary fiber fine ⁇ generated (in ⁇ itu during mechanical refining of cellulo ⁇ ic pulp ⁇ , the latte fine ⁇ being defined a ⁇ miniature fibers pa ⁇ ing through a 200 me ⁇ h ⁇ creen.
- the extraneou ⁇ cellulosic microfibrils who ⁇ a ⁇ pect ratio (the ratio of length to diameter) is 10 to 100 times higher than that of fiber fines, can be obtained exclu sively by the process referred to hereinafter as well as i the claims to follow as the "cascade-microfibrillation" pro ce ⁇ .
- cellulosic fibers derive preferably from cotton or well-fibrillating cellulosic pulp undergo the following consecutive proce ⁇ ing ⁇ teps: (a) dry or wet chopping of fibers to a length preventin a hydraulic ⁇ pinning during the ⁇ ub ⁇ equent wet refining, th re ⁇ ultant length being dependent upon both the furni ⁇ h ⁇ olid and type of refining equipment to be employed in ⁇ ub ⁇ equen proce ⁇ ing; (b) preliminary refining of chopped fibers resultin from ⁇ tep (a) at the highe ⁇ t practically fea ⁇ ible ⁇ olids con centration ⁇ , e.g., of up to 30-35%, by weight, preferably i the pre ⁇ ence of ⁇ odium ⁇ ilicate, Congo red and/or other inor ganic and organic fibrillation-enhancing agents; (c) additional refining of the fiber ⁇ re ⁇ ulting fro ⁇ te
- the process of the present invention i ⁇ also most suit able for the manufacture of advanced wet-laid nonwoven prod uct ⁇ on a paper machine.
- Contemporary nonwovens as a clas of material ⁇ , are manufactured in two con ⁇ ecutive proce ⁇ sin step ⁇ .
- the fir ⁇ t ⁇ tep involve ⁇ preforming of unbounded fibe webs (mats) u ⁇ ing either a wet-laid approach or the currentl predominant dry-forming approach.
- the preformed web ⁇ made up mainly of ⁇ ynthetic fiber ⁇ have no cohe ⁇ ive ⁇ trength ⁇ uitable adhe ⁇ ive ⁇ mu ⁇ t be incorporated into the web ⁇ in th ⁇ econd proce ⁇ ing ⁇ tep to e ⁇ tabli ⁇ h adhe ⁇ ive joints betwee adjacent fibers.
- the principal method of imparting the desired level o cohesive ⁇ trength to the preformed webs is by saturating the with acrylic latexes to attain an adhesive content of up t 20%, by weight, followed by drying.
- Another method relies o "blowing" a relatively coarse thermopla ⁇ tic adhe ⁇ ive powder ⁇ u ⁇ pended in air, into the preformed mat u ⁇ ing electrostati as ⁇ i ⁇ t, followed by a thermal fu ⁇ ing of adhe ⁇ ive particle depo ⁇ ited between the fiber ⁇ .
- the method of the papermaking proce ⁇ of the present invention makes it pos ⁇ ible to manufacture novel and improved wet-laid nonwoven product ⁇ with unique functional propertie ⁇ and material characteri ⁇ tic ⁇ , not attainable with the aid of the nonwoven-manufacturing technologie ⁇ of the prior art.
- the latter advancement ⁇ are realized by floccu ⁇ lating ⁇ pecially de ⁇ igned multico ponent nonwoven furni ⁇ he ⁇ with the in- ⁇ itu synthesized complex functional microgels and forming wet-laid nonwoven webs on a paper machine.
- the above multicomponent furnishes can be incomparably more diversified and complex than furnishe ⁇ u ⁇ ed in the nonwoven-manufacturing technologie ⁇ of the prior art, comprising, among other things, synthetic fibers; ⁇ ynthetic reinforcing microfibrils; polymer- emul ⁇ ion adhe ⁇ ive ⁇ , particularly the previously mentioned novel acrylic ultrafine polymer-emulsion adhesives; novel waterborne rubber cements; aqueou ⁇ dispersions of fine- particle-size thermoplastic adhesive powders with a preferred average particle diameter of about 0.5 ⁇ m; organic dyes; and bioactive material ⁇ ; the advantage ⁇ of the above functional additive ⁇ being explained in more detail hereinafter.
- the overpowering flocculation mechani ⁇ m a the foundation of the papermaking proce ⁇ s of the presen invention allows one to u ⁇ e well-di ⁇ per ⁇ ed, highly diver ⁇ ifie furni ⁇ h compo ⁇ ition ⁇ , invariably generating extremely unifor micrograin ⁇ tructure ⁇ in the flocculated furni ⁇ he ⁇ .
- very uniform wet-laid nonwoven web ⁇ can be preforme at considerably higher paper machine speed ⁇ , u ⁇ ing longe fiber ⁇ , than are fea ⁇ ible in the nonwoven-making technologie of the prior art.
- the manufacture of raw wet-laid nonwoven webs is greatl facilitated by incorporating into the furnish up to 5%, b weight, in relation to furnish solid ⁇ , of the novel ultrafin polymer-emul ⁇ ion adhe ⁇ ive ⁇ and/or novel waterborne rubbe cement ⁇ with pronounced wet-tack propertie ⁇ .
- the second process stage in making wet-laid nonwovens ca be eliminated completely with the papermaking process of th present invention by incorporating thermoplastic adhesive pow ders directly into nonwoven furnishe ⁇ .
- the adhesive powder in que ⁇ tion employed in the form of fine-particle- ⁇ iz aqueou ⁇ di ⁇ per ⁇ ion ⁇ , are retained in raw wet-laid nonwove web ⁇ on the forming ⁇ creen in exactly the ⁇ ame manner a ordinary filler pigment ⁇ are retained in paper webs, withou contaminating paper-machine felts.
- Attractive, novel, uniquely ⁇ trong nonwoven product ⁇ ca be obtained with the aid of the papermaking proce ⁇ of t pre ⁇ ent invention from furni ⁇ he ⁇ containing well-di ⁇ per ⁇ ⁇ ynthetic fiber ⁇ , reinforcing ⁇ ynthetic microfibril ⁇ , ultra fine acrylic polymer-di ⁇ per ⁇ ion adhe ⁇ ive ⁇ and/or waterbor rubber cement ⁇ , a ⁇ well a ⁇ the previou ⁇ ly mentioned aqueo dispersions of fine-particle-size thermopla ⁇ tic adhe ⁇ i powder ⁇ .
- the functional propertie ⁇ under di ⁇ cu ⁇ ion mu be imparted to nonwoven product ⁇ by way of ⁇ pecial, ⁇ epara aftertreatment ⁇ .
- a certain level of intrins hygro ⁇ copic properties is imparted automatically to wet-la nonwoven products made with the aid of the in-situ synthesiz complex microgels, by virtue of these microgels' pronounced polar nature, while yet higher levels of hygroscopic prope ties are obtained by adding hydrophilic anionic or nonioni polymers directly to wet-laid-nonwoven furnishes or by addin hydrophilic cationic polymers to the solution ⁇ of calciu chloride or equivalent cro ⁇ -linking ⁇ alts.
- Bio ⁇ tatic and/o biocidal propertie ⁇ can ⁇ imilarly be imparted to wet-laid non woven product ⁇ by adding ⁇ uitable bio ⁇ tatic and/or biocida material ⁇ into wet-laid-nonwoven furni ⁇ he ⁇ .
- the papermaking proce ⁇ of the pre ⁇ ent invention i ⁇ al ⁇ uniquely ⁇ uitable for manufacturing wet-laid nonwoven web re ⁇ i ⁇ tant to high temperature ⁇ , u ⁇ ing furnishes comprisin thermally re ⁇ i ⁇ tant inorganic fiber ⁇ .
- u ⁇ ing furnishes comprisin thermally re ⁇ i ⁇ tant inorganic fiber ⁇ .
- paper and wet-laid nonwoven webs containin intrinsically deposited magnetic powders are uniquely suite for printing of counterfeit-proof, virtually inde ⁇ tructibl (when made of nonwoven ⁇ ) banknotes, the magnetic respon ⁇ e o ⁇ uch banknote ⁇ being measurable quickly and conveniently wit the aid of inexpensive countertop detectors.
- the paper (nonwoven) process of the present invention may be executed in actual paper mill operations in several differ ent fashions.
- paper, board or wet laid-nonwoven furnishes are flocculated with the aid of in situ synthesized complex functional microgels immediatel before entering the chest or after leaving the chest on th way to the headbox.
- hydrogen peroxide is preferably incorporated into th furnish prior to, or ⁇ imultaneou ⁇ ly with, the addition of th highly alkaline solutions of sodium silicate and sodium alumi nate (zincate) .
- the most preferable approach is to carry out the furnis flocculation in a fully continuous mode, using in-line mixers reactors, exemplified by the following consecutive ⁇ tep ⁇ :
- Both above half ⁇ tream ⁇ are recombined in the ⁇ ubsequent processing statio (in-line mixer-reactor) to form, in situ, the transient chemi cally reactive subcolloidal hydrosol, the solution of t cross-linking agent(s) being injected into the recombine halfstreams in the subsequent processing station to form, i situ, the complex functional microgel cements.
- statio in-line mixer-reactor
- th sequence of the individual proces ⁇ ing steps in the genera proces ⁇ of the pre ⁇ ent invention may be rever ⁇ ed by addin ⁇ olution ⁇ of bivalent and/or multivalent inorganic cro ⁇ linking ⁇ alt ⁇ to the furni ⁇ h in ⁇ tep (a) ; separately pre paring the transient reactive ⁇ ubcolloidal ⁇ odium- ⁇ ilico aluminate or ⁇ imilar hydrosols in step (b) ; and blending i ⁇ tep (c) the ⁇ y ⁇ tem ⁇ re ⁇ ulting from ⁇ tep ⁇ (a) and (b) to for in ⁇ itu a complex functional calcium- ⁇ ilico-aluminate or ⁇ imi lar microgel cement and flocculate the furni ⁇ h instantaneous ly, indiscriminately and completely, thus obtaining a maxim suitable for making paper, board and other wet-laid product on a paper machine.
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- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Paper (AREA)
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU34728/93A AU666168B2 (en) | 1992-08-20 | 1993-01-12 | Acid-to-alkaline papermaking process |
EP93903481A EP0658229A4 (en) | 1992-08-20 | 1993-01-12 | Acid-to-alkaline papermaking process. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US07/932,663 | 1992-08-20 | ||
US07/932,663 US5240561A (en) | 1992-02-10 | 1992-08-20 | Acid-to-alkaline papermaking process |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1994004752A1 true WO1994004752A1 (en) | 1994-03-03 |
Family
ID=25462688
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1993/000320 WO1994004752A1 (en) | 1992-08-20 | 1993-01-12 | Acid-to-alkaline papermaking process |
Country Status (7)
Country | Link |
---|---|
EP (1) | EP0658229A4 (en) |
CN (1) | CN1082132A (en) |
AR (1) | AR246992A1 (en) |
AU (1) | AU666168B2 (en) |
CA (1) | CA2142367A1 (en) |
TW (1) | TW283178B (en) |
WO (1) | WO1994004752A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6004928A (en) * | 1997-05-13 | 1999-12-21 | Biomeasure, Incorporated | Method of treating hyperlipidemia |
EP2062914A2 (en) | 2001-06-08 | 2009-05-27 | Ipsen Pharma | Somatostatin-dopamine chimeric analogs |
WO2014197938A1 (en) | 2013-06-13 | 2014-12-18 | Antisense Therapeutics Ltd | Combination therapy |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102628240A (en) * | 2012-04-24 | 2012-08-08 | 陕西科技大学 | Multilayer starch coated wheat straw chemical pulp method |
CN108999032B (en) * | 2018-09-07 | 2021-01-05 | 宿州学院 | Preparation method of modified plant fiber filter paper |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3128223A (en) * | 1960-10-28 | 1964-04-07 | Hoechst Ag | Process for improving the retention of mineral fillers in the formation of paper fleeces |
US4954220A (en) * | 1988-09-16 | 1990-09-04 | E. I. Du Pont De Nemours And Company | Polysilicate microgels as retention/drainage aids in papermaking |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5116418A (en) * | 1984-12-03 | 1992-05-26 | Industrial Progress Incorporated | Process for making structural aggregate pigments |
-
1993
- 1993-01-12 WO PCT/US1993/000320 patent/WO1994004752A1/en not_active Application Discontinuation
- 1993-01-12 EP EP93903481A patent/EP0658229A4/en not_active Ceased
- 1993-01-12 CA CA 2142367 patent/CA2142367A1/en not_active Abandoned
- 1993-01-12 AU AU34728/93A patent/AU666168B2/en not_active Ceased
- 1993-04-16 TW TW82102906A patent/TW283178B/zh active
- 1993-05-29 CN CN 93106423 patent/CN1082132A/en active Pending
- 1993-05-31 AR AR32504893A patent/AR246992A1/en active
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3128223A (en) * | 1960-10-28 | 1964-04-07 | Hoechst Ag | Process for improving the retention of mineral fillers in the formation of paper fleeces |
US4954220A (en) * | 1988-09-16 | 1990-09-04 | E. I. Du Pont De Nemours And Company | Polysilicate microgels as retention/drainage aids in papermaking |
Non-Patent Citations (1)
Title |
---|
See also references of EP0658229A4 * |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6004928A (en) * | 1997-05-13 | 1999-12-21 | Biomeasure, Incorporated | Method of treating hyperlipidemia |
EP2062914A2 (en) | 2001-06-08 | 2009-05-27 | Ipsen Pharma | Somatostatin-dopamine chimeric analogs |
WO2014197938A1 (en) | 2013-06-13 | 2014-12-18 | Antisense Therapeutics Ltd | Combination therapy |
Also Published As
Publication number | Publication date |
---|---|
AR246992A1 (en) | 1994-10-31 |
EP0658229A4 (en) | 1997-10-08 |
CA2142367A1 (en) | 1994-03-03 |
AU666168B2 (en) | 1996-02-01 |
CN1082132A (en) | 1994-02-16 |
TW283178B (en) | 1996-08-11 |
EP0658229A1 (en) | 1995-06-21 |
AU3472893A (en) | 1994-03-15 |
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