WO2009085655A1

WO2009085655A1 - Repulpable paper compositions

Info

Publication number: WO2009085655A1
Application number: PCT/US2008/086571
Authority: WO
Inventors: Ti Chou; Martin A. Cohen
Original assignee: Lubrizol Advanced Materials, Inc.
Priority date: 2007-12-20
Filing date: 2008-12-12
Publication date: 2009-07-09

Abstract

Conventional latexes for paper saturants are modified to enhance repulpability. They can be modified with high acid content polymers or they can be polymerized with increased amounts of ethylenically unsaturated monomers with acid groups. The resulting paper for such saturants/binders has sufficient physical properties but the paper is more easily recycled using high shear mixers at elevated pH values. These saturants, when formed into films, are characterized by reduced stress to break after soaking in pH 10.

Description

REPULPABLE PAPER COMPOSITIONS

FIELD OF THE INVENTION

[0001] The present invention relates to the inclusion of a modified paper saturant/binder including elevated levels of repeat units from copolymeri/able unsaturated acid monomers for treating paper/nonwovens so that the treated paper/nonwoven is repulpable under moderate to high shear. Thus, once the paper/nonwovens are treated with compositions of the present invention, they can be repulped either before actual use, for example scrap during start-up or shut down, as well as after some intermediate processing steps, such as after an elevated temperature cure.

BACKGROUND OF THE INVENTION

[0002] Historically, paper and nonwovens after being saturated with a polymeric binder in latex or dispersion form and dried are not readily repulpable. Thus, scrap paper from start-up, shut-down, non-stable operating conditions, conversion scrap, recovered trimming and cutting are disposed of in landfills. That is, the paper cannot be re- dispersed into individual fibers or small groups of -fibers suitable for paper manufacturing and fed back into the paper making process as a raw material (pulp). A variety of fibers (often from cellulose sources but not limited to cellulose) are available for papermaking and the particular characteristics of each fiber group has a significant influence on the strength and flexibility of the resulting paper. Long flexible fibers give high strength and good flexibility (desirable properties in paper), Short inflexible fibers are less desired and typically give lower strength. Recovered fibers from paper products often have shorter length and more fiber fragments than virgin fibers. [0003] Conventional paper saturants/binders generally survive moderate or high shear better than the fibers. Said fibers being more brittle and having higher aspect ratios than saturant/binder tend to fragment into shorter fibers. Thus, subjecting a commercial binder treated paper to high shear results in fiber breakage until one is left with shorter fibers and some cluster of short fibers extending from branch points adhered firmly by saturant/binder. Thus, conventional logic is that recycled fibers from one paper type may be suitable to form a paper tolerant of shorter fibers but cannot easily be used to make a paper of equivalent physical strength and flexibility to a paper from virgin fibers. [0004] Alkali soluble polymers are known and have been used as the entire saturant binder in U.S. Patent 6,458,230 to BASF and U.S. Patent 4,278,727 to Wacker-Chemie. The concept behind these patents is to get high paper wet strength at neutral pH and have the saturant/binder dissolve at higher pH to allow separation of the saturant binder without having to apply high shear, These patents were an improvement over the prior art where the saturant binder was subjected to high pH and high temperature to degrade the polymer into alkali or acidic water soluble species. Then, the water soluble binder could be separated from the fiber. The improvement allowed the dissolution of the binder/saturant polymer at a moderate pH (e.g., about 10 or 1 1} at lower temperatures than prior art polymer chemical degradation processes to render the polymer alkali or acidic water soluble.

[0005] U.S. Patent 5,133,833 relates to a process for repulping or reclaiming fibers from latex-impregnated materials such as latex impregnated papers. The process involves treating the latex-impregnated material with an alkali solution for a sufficient period of time to separate the latex polymer from the fibers. This is followed by a washing step to rinse away the latex polymer thereby leaving the reclaimed fibers for subsequent use such as the formation of new paper stock.

SUMMARY OF THE INVENTION

[0006] Alkali sensitive acrylate, or styrene-butadiene, or styrene-acrylate, or vinyl chloride, or vinylidene chloride, or vinyl acetate copolymers are used as a component in paper or nonwoven binder/saturant to render the resulting paper and/or nonw ovens repulpable under moderate to high shear. That is, during manufacture, after manufacture and after use the papcr/nonwoven can be disseminated or dispersed into small groups or individual pulp/fibers at elevated pH whereupon the pulp/fibers of the paper/nonwoven, along with any attached polymer can be commercially recycled. The alkali sensitive acrylate, or styrene-butadiene, or styrcnc- acrylate, or vinyl chloride, or vinylidene chloride, or vinyl acetate binder composition is generally a copolymer derived from at least an unsaturated acid monomer and a) one or more alkyl (alk)acrylates monomers and/or b) styrene-butadiene monomers c) styrene-acrylate monomers d) vinyl chloride monomers e) vinylidene chloride monomers f) vinyl acetate monomers optionally one or more other unsaturated monomers such as vinyl esters, vinyl ethers, acrylamides or the like, Repulpable nonwoven/paper sources include abrasive paper, vacuum bags, wipes, book covers, wallcoverings, and the like,

DETAILED DESCRIPTION OF THE INVENTION

[0007] Various types of paper and nonwovens are conventionally treated with a saturant/binder which generally is a latex (anionic, nonionic, or cationic) reinforcing polymer and optionally containing crosslinking agents. Saturant/Binder is able to enhance physical properties (such as Tensile Strength, Fold Endurance, Tear Resistance, Bursting Resistance, etc.), chemical resistance, and durability to the treated paper/nonwovens. The network of fibers in generic paper generally comprises at least about 50 percent by weight of cellulosic fibers. In specialty nonwovens, the percentage of non-cellulosic fibers can be much higher than in generic paper. Thus, non-cellulosic fibers such as mineral and synthetic fibers may be included, if desired. Examples of non- cellulosic fibers include, by way of illustration only, glass wool and fibers prepared from thermosetting and thermoplastic polymers.

[0008J In many paper embodiments, substantially all of the fibers present in the paper will be cellulosic fibers. Sources of cellulosic fibers include, by way of illustration only, woods, such as softwoods and hardwoods; straws and grasses, such as rice, esparto, wheat, rye, and sabai; bamboos; jute; flax; kenaf; linen; ramie; abaca; sisal; bagasse; and cotton and cotton linters. Softwoods and hardwoods are the more commonly used sources of cellulosic fibers in North America and in Europe. The cellulosic fibers may be obtained by any of the commonly used pulping processes, such as mechanical, chemi- mechanical, semi-chemical, and chemical processes. For example, softwood and hardwood Kraft pulps are desirable for toughness and tear strength, but other pulps, such as recycled fibers, sulfite pulp, and the like may be used, depending upon the application. [0009] Typically, a saturant/binder in the saturated paper/nonwoven is at a level of from about 5 to about 100 percent, based on the dry weight (solids/nonvolatiles) of the fibrous web (typically 100% fiber at this stage). For example, the saturant may be present in the saturated paper at a level of from about 10 to about 70 weight percent. As another example, the saturant may be present in the saturated paper at a level of from about 15 to about 60 weight percent. f 00 IG] Generally, many saturants/binders known to the art and to the literature can be the starting point for an improved saturant for repulpable paper. Such saturants often include from about 70 to about 98 or 100 percent, on a dry weight basis, of an addition synthetic polymer (e.g., latex or dispersion) having a glass transition temperature of from about -4O⁰C to about 7O⁰C. By way of example, the solids content of the saturant/binder when applied may be from about 4 to about 80 percent of the applied saturant. Further, by way of example, the addition polymer dispersion reinforcing polymer may have glass transition temperature of from about -15⁰C to about 15⁰C. The saturant/binder can be combined with the fibers or fibrous web by any conventional method such as beater addition, saturation, impregnation, spray, coating, etc. Also, by way of example, substantially all of the fibers of the paper can be cellulosic fibers. The latex reinforcing polymer may be anionic, nonionic. catϊonic and/or mixtures.

[OGIl] The improved saturant of this disclosure can be prepared by any process. Two preferred processes will be referred to as either the one-component saturant or the two-component saturant. The two-component saturant is a blend of two separate polymers wherein the blend has the requisite properties (including alkali sensitivity) due to a lesser amount on a weight basis of a second high acid content polymer. The high acid content polymer contributes alkali sensitivity to the blend in the two-component saturant. The other polymer in the two-component blend is any of the conventional latexes used as paper saturants. The one-component saturant uses higher amounts of acid monomers in a recipe to make a conventional latex paper saturant. The acid monomers, when used in appropriate amounts, make the one-component saturant as sensitive to alkali as the two-component saturant. We will refer to the two-component saturant and the one-component saturant as being alkali sensitive. The one-component and two-component systems can be used interchangeably in making saturant for repulpable paper. Either method of imparting alkali sensitivity gives similar properties, i.e., it produces a repulpable paper. [0012] The high acid content polymer used in the two-component saturant can be a solution in aqueous phase, a latex, or a dispersion. Generally, these high acid polymers comprise about 4 to about 20 wt% of repeating units from an ethylenically unsaturated monomer(s) having one or more acid groups (preferably carboxylic acid, but including sufonic acid, phosphoric or phosphonic acid, etc.), These repeating units can be in the acid form or in the form of a neutralized salt of the acid. Commercial examples of the above noted alkali sensitive or dispersions that can impart alkali sensitivity into a conventional saturant/binder latex are available as Carboset® resins made by Lubrizol Advanced Materials, Inc., Brecksville, Ohio, their headquarters. Desirably, the Carboset 500 series can be utilized and include Carboset 51 1 , Carboset 514H, Carboset 514A, Carboset 515, Carboset 519, Carboset 527, Carboset 537, and Carboset 552 with Carboset 511, 527, 537, 514H, 514W, 515, and 552 being preferred. Alternatively, a hydrosol with similar monomer composition may be utilized. Desirably, these Carboset type polymer dispersions are blended as the 5 to 40 weight % substitution level on a dry basis with the polymer of a conventional saturant/binder (i.e., 5 to 40 weight percent of the polymer of the saturant would be replaced with 5-40 weight percent of a high acid content polymer). Generally, any type of polyacid polymers, such as Carbosperse K-700 from The Lubrizol Corporation, can be used to replace 5 to 40 percent weight of saturant/binder and to impart alkali sensitivity of the blend.

[0013] Alternatively, the acid monomers associated with the pH sensitivity could be included in the polymerization recipe of a commercial or conventional saturant or binder to make a one-component saturant/binder with alkali sensitivity. For example, polymer with a composition of 91 ,5 ethyl acrylate / 3.0 acrylonitrile < 1.0 N-methylol aerylamide / 4.5 acrylic acid, or 92.0 ethyl acrylate / 0.7 aerylamide / 4.5 acrylic acid / 1.9 itaconic acid are alkali sensitive saturant/binder,

[0014] Described below are fairly conventional latex saturants for use in papermaking. These latexes may be used as described as the major component in a two- component repulpable latex saturant with alkali sensitivity according to the invention. If a single component latex saturant is desired, these latexes below could be polymerized with the appropriate amount of ethylenically unsaturated acid containing monomers substituted for a portion of the conventional monomers to these recipes. If the substitution of cthylenically unsaturated acid containing monomers were to be made to prepare a one-component alkali sensitve saturant, then the amount of conventional monomers would have to be reduced by an amount from about 1 to about 7 wt.% to allow the substitution.

[0015] Examples of suitable latex reinforcing polymers include acrylate polymers or copolymers, styrene-butadienc copolymers, vinyl-acetate polymers or copolymers, styrene-acrylate copolymers, vinyl chloride copolymers, vinylidene chloride copolymers, or a vinyl acetate- ethylene copolymer. These polymers may be anionicaily, nonionicaJly, and/or cationically stabilized colloidal dispersions or blends thereof. Suitable polyacrylates include alkyl (alk)acrylate polymer wherein the alkyl has from 1 to about 15 carbon atoms (such that the (alk)acrylic acid ester has from 4 to 18 carbon atoms) such as ethyl acrylate, butyl acrylate, etc., along with blends of various other polymers such as acrylonitrile polymers, styrene-butadiene copolymers, styrene-acrylate copolymers, vinyl chloride copolymers, vinylidene chloride copolymers, vinyl acetate copolymers, ethylene-vinyl chloride copolymers and the like. When the saturant/binder is an acrylate polymer dispersion desirably from about 50 to about 98 weight % of the repeating units of said polymer are C₄-Ci₈ (alk)acrylate monomers and in another embodiment from about 70 to about 98 wt.% of said repeating units are said (alk)acrylate monomers. Desirably, the alkyl portion of said monomers is a Cl to Cl 5 alkyl group without heteroatoms such as oxygen or nitrogen. In still another embodiment, the alkyl (alk)acrylate have from 4 to 1 1 carbon atoms, more desirably from 4 to 7 carbon atoms. The residual monomers forming repeating units can be selected from the unsaturated monomers listed later in this document,

[0016] When the saturant/binder is a styrene-butadiene polymer dispersion (meaning it is formed from a styrenic type monomer as listed beiow and a conjugated diene monomer) desirably from about 30 to about 70 weight % of said polymer is repeating units derived from a styrenic monomer and from about 29 to about 70 weight % repeating units derived from polymerizing a conjugated diene monomer of 4 to 6 carbon atoms. In another embodiments, from about 35 to about 65 weight % of the repeating units are derived from a styrenic monomer and from about 34 to about 65 weight percent of repeating units are derived from polymerizing a conjugated diene of 4 to 6 carbon atoms. In a preferred embodiment, the styrenic monomer is styrene. In a preferred embodiment, the diene monomer comprises butadiene and/or is substantially butadiene. Other ethylenically unsaturated monomers can be copolymerized with the styrenic monomer and diene monomer as is well known to the art.

}0017| If the saturant binder is a vinyl acetate polymer, desirably from about 20, 30 or 50 to about 98 or 99 weight percent of the repeating units of the polymer are derived from polymerizing vinyl ester monomers of 4 to 20 carbon atoms such as vinyl acetate and other monomers where the acetate is replaced by other carboxylic acids. To avoid a situation where the vinyl acetate polymer might also be characterized as an acrylate polymer, the vinyl acetate polymer desirably has less than 50 weight percent of the repeating units of alkyl acrylates as previously described. If more than 50 weight percent of the repeating units are from alkyl acrylates, the polymer will be called an acrylate polymer. The other repeating units of the vinyl acetate polymer are any of the other ethylenically unsaturated monomers listed in this disclosure. The acetate polymer will be appropriately modified to be a one-component or two-component material with alkali sensitivity.

[0018] If the saturant is a vinyl chloride polymer, desirably from about 20, 50, 60, 70 or 80 to about 98 or 99 weight percent of the repeating units are derived from polymerizing vinyl chloride monomer. The residual monomers can be any of the ethylenically unsaturated monomers listed in this disclosure that readily co-polymerizc with the vinyl chloride monomer.

[0019] If the saturant is a vinylidene chloride polymer, desirably from about 35, 50, 60, 70 or 80 to about 98 or 99 weight percent of the repeating units are derived from polymerizing vinylidene chloride monomer. Since vinylidene chloride homopolymer can be highly crystalline, it is often desirable to use relatively large amounts of co- monomers to disrupt crystal Unity. The residual repeating units can be derived from polymerizing any of the other ethylenically unsaturated monomers listed in this disclosure that readily copolymerize with vinylidene chloride. Examples of copolymerizable monomers with vinylidene chloride include acrylates, methacrylates, acrylonitrile. and the vinyl carboxylic acids such as acrylic acid, itaconic acid, and maleic anhydride or its diacid form. [0020J The saturated paper of the present invention may be made in accordance with any known procedures. Briefly, and by way of illustration only, the web may be made by preparing an aqueous suspension of fibers, optionally with at least about 50 percent, by dry weight, of the fibers being cellulosic fibers; distributing the suspension on a forming wire; removing water from the distributed suspension to form a paper; and treating the paper with the saturant. In general, the aqueous suspension is prepared by methods well known to those having ordinary skill in the art. Similarly, methods of distributing the suspension on a forming wire and removing water from the distributed suspension to form a paper also are well known to those having ordinary skill in the art. The web can also be made by a well known airlaid nonwoven process. The drylaid or airlaid web is treated with binder using spray process.

[0021] The expressions "by dry weight" and "based on the dry weight of the cellulosic fibers" refer to weights of fibers, e.g., cellulosic fibers, or other materials which are essentially free of water in accordance with standard practice in the papermaking art (dried to constant weight at 105⁰C). When used, such expressions mean that weights were calculated as though no water were present.

[0022] If desired, the paper formed by removing water from the suspension of fibers may be dried prior to the treatment of the paper with the saturant. Drying of the paper may be accomplished by any known means. Examples of known drying means include, by way of illustration only, convection ovens, radiant heat, infrared radiation, forced air ovens, and heated rolls or cans. Drying also includes air drying without the addition of heat energy, other than that present in the ambient environment.

[0023] In addition to non-cellulosic fibers, the aqueous suspension may contain other materials or additives as is well known in the papermaking art. For example, the suspension may contain acids and bases to control pH, such as hydrochloric acid, sulfuric acid, acetic acid, oxalic acid, phosphoric acid, phosphorous acid, sodium hydroxide, potassium hydroxide, ammonium hydroxide or ammonia, sodium carbonate, sodium bicarbonate, sodium dihydrogcn phosphate, disodium hydrogen phosphate, and trisodium phosphate: alum; sizing agents, including cationic starches, alkyl ketene dimers, rosin and rosin acids, various styrene-acrylate emulsions, copolymers of styrene and maleic anhydride, and the like: dry strength adhesives, such as natural and chemically modified starches and gums; cellulose derivatives such as carb ox ym ethyl cellulose, methyl cellulose, and hemicellulose; synthetic polymers, such as phenolics, polyamines, and polyacrylamides; wet strength resins, such as urea-formaldehyde resins, melamine- formaldehyde resins, and polyamides; fillers, such as clay, talc, calcium carbonate, and titanium dioxide; coloring materials, such as dyes and pigments; retention aids; fiber deilocculants; soaps and surfactants; defoamers; drainage aids; optical brighteners; pitch control chemicals; slimicides; and specialty chemicals, such as corrosion inhibitors, flame-proofing agents, and anti-tarnish agents. Processing agents are also generally utilized in fairly large amounts and the same includes various defoamers, retention aids which enhance flocculation of fiber slurry so that very fine fibers are agglomerated and thus form a flock which is more easily processed. Various dyes and pigments can also be utilized. Examples of optional cationic polymers include, by way of illustration only, polyamides, amide-epichlorohydrin resins, polyethylcneimines, polyacrylamides, and urea- formaldehyde resins.

[0024] The above conventional latexes or saturants containing conventional additives while generally producing paper having suitable properties did not permit the paper to be recycled or repulped as set forth herein or by conventional means. [0025] In order to obtain repulpable paper, it is an important aspect of the present invention that a higher acid monomer content be present in the saturant/binder. In the one components system, a portion of the repeating units of a conventional saturant latex are replaced with repeating units from unsaturated acid monomers. In the two- component saturant approach, this can be accomplished by substituting from about 5 to about 40 weight percent, in one embodiment from 5 to about 30 weight percent, in still another embodiment from about 5 to about 25 percent by weight of a convention acrylate, or styrene-butadiene, or styrene-acrylate, or vinyl chloride, or vinylidene chloride, or vinyl acetate latex copolymers with polymers high in repeating units derived from ethylenically unsaturated acid monomers.

[0026] An important aspect of the present invention is utilization of alkali sensitive repeating units/polymers for saturating paper, cellulose, and the like using either the one- component or two-component saturant. The alkali sensitive polymers are copolymers derived from at least two or optionally three or more different monomers with at least one of the monomers being an unsaturated acid. The paper, cellulose, etc., is generally made repulpable by the substitution of alkali sensitive addition polymer dispersion, desirably having the specified percentages of repeating units derived from unsaturated carboxylic acid monomers. Preferred copolymers are derived from unsaturated acid monomers, one or more alkyl (alk)acrylates, styrene-butadiene, styrene-acrylate, vinyl chloride, vinylidene chloride, or vinyl acetate or derivatives thereof. Desirable copolymers include any of the above one or more monomers with at least one unsaturated acid. Dispersion is a broader term than latex in this description and is used to indicate one or more polymers in a media, wherein at least one of the polymers is in a dispersed phase. An additional polymer(s) may be present as a dispersed and/or dissolved phase.

[0027] In this specification, the term alkyl (alk)acrylate will refer to alkyl acrylates and/or alkyl alkacrylates where alkyl refers to the alcohol based moiety reacted with the carboxylic acid and the (alk) refers to an optional alkyl group on the beta carbon of the unsaturated monomer. While these can be made in various ways, they are often referred to as esters of the reaction between acrylic acid or (alk)acrylic acid and various alcohois. A preferred embodiment of the saturant/binder latex is aikyl (alk)acrylate polymers with high percentages e.g., above 51 or 70 weight % of repeating units from alkyl (alk)acrylates with 4-18 carbon atoms. When referring to these minimal percentages of alkyl (aJk)aerylates in the latex, we will be referring to such monomers without heteroatoms such as nitrogen in the R¹ group as shown below. When referring to other alkyl (alk)acrylates that may be present in smaller amounts within any of the polymers, we will be using the broader definition of alkyl (alk)acrylates which include things like cyanoalkyl, hydroxyalkyl, epoxyalkyl, etc. in the R¹ group. [0028J The various alkyl acrylates (or esters or acrylic acid) have the formula

O CH₂=CH-C-OR' _{foraiula l}

where R¹ is an alkyl group containing 1 to about 15 carbon atoms, an alkoxyalkyl group containing a total of 1 to about 10 carbon atoms, a cyanoalkyl group containing 1 to about 10 carbon atoms, or a hydroxy alkyl group containing from 1 to about 18 carbon atoms. The alkyl structure can contain primary, secondary, or tertiary carbon configurations and normally contains 1 to about 10 carbon atoms with 2 to 8 carbon atoms being preferred. Examples of such acrylic esters include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-pentyl acryiate, isoamyl acrylate, n-hexyl acrylate, 2-methylpentyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-decyl acrylate, n-dodecyl acrylate, n-octadecyl acrylate, and the like. Preferred examples include ethyl acrylate, butyl acrylate, 2-ethyl hexyl acrylaie, and the like. [0029] The various alkyl alkacrylates (or esters of alkacrylic acid) have the formula

R² O

I!

CH ,=c- -C-OR Formula 2

wherein R¹ is as set forth above with respect to Formula 1 and R² is an alkyl having from 1 to about 4 carbon atoms, desirably 1 or 2 carbon atoms with methyl being especially preferred. Examples of various alkyl (aik)acrylates include methyl methacrylate, ethyl methacrylate, methoxymethyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, butoxy ethyl acrylate, ethoxypropyl acrylate, and the like. Derivatives include hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, and the like. Mixtures of two or more of the above monomers can also be utilized. [0030] An important aspect of the present invention is a utilization of ethylenically unsaturated acids in the formation of a) a one-component saturant such as an alkali sensitive acrylate, styrene-butadiene, styrene- acrylate, vinyl chloride, vinylidene chloride, or vinyl acetate latex polymers or b) a high acid content polymer blended with a conventional paper saturant polymer. Such acids are unsaturated acids and include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, 2-carboethyl acrylate and the like. Acrylic acid is preferred. Half esters of the above earboxylic acids can also be used as monomers wherein the ester portion is desirably an alkyl having from 1 to about 10 carbon atoms and specific examples include mono methyl maleate, mono methyl fumerate, mono methyl itaconate, and the like. [0031 ] The amount of repeating units from the one or more unsaturated acids is very important in forming the one-component alkali sensitive latex polymers. The amount of add monomer varies somewhat depending on how oleophilic the other monomers in the addition polymer dispersion/latex (saturant/binder) are. For acrylate polymers and vinyl acetate polymers generally about 2 to about 4,5 or 6 weight %. in another embodiment from about 2.4 or 2.6 to about 5 or 6 weight % of the total dry weight of the alkali sensitive addition polymer dispersion is said repeating units from unsaturated acid monomers. For styrene-butadiene polymers, vinyl chloride polymers, and vinylidene chloride polymers generally about 1 to about 7 weight %, in another embodiment from about 1.4 or 1.6 to about 3, 4, 5 or 6 weight % of the total dry weigh to the alkali sensitive addition polymer dispersion is said repeating units from acid monomers. The preferred unsaturated acid monomer is unsaturated mono or dicarboxylic acid monomers. In one embodiment, the unsaturated acid monomers include unsaturated sulfonic acid monomers and/or unsaturated phosphonic or phosphoric acid monomers. The amount of acid may need to be adjusted slightly with the particular type of acid and the particular type of copolymer formed for optimal performance. Care should be taken not to use excessive amounts of acid inasmuch as the paper will become water sensitive. [0032] The polymer from at least one alkyl (alk)acrylate, vinyl chloride, vinylidene chloride, vinyl acetate, styrene-butadiene, or styrene-acrylate monomers along with the one or more unsaturated acid monomers form a preferred alkali sensitive latex copolymer for the addition polymer dispersion. While other monomers can be utilized to form the copolymer or other different copolymers, the amount of dry weight of the repeating units from acrylate, alkyl (alk)acrylate, vinyl chloride, vinylidene chloride, vinyl acetate, styrene, butadiene, vinyl acetate and unsaturated acid repeat groups along with any/all the alkali sensitive latex polymers (utilized in a two-component system) is generally a majority and desirably at least about 70 or at least about 75 percent by weight of the total polymers in the saturant/binder on a dry weight basis.

[0033 j Other co-polymerizable (ethyl enical Iy unsaturated) monomers in lesser amounts may be utilized to make the one or more alkali sensitive latex copolymers including styrenic monomers {as a co-monomer in the acrylate latex), vinyl chloride type monomers, acrylonitrile type monomers, various vinyl ester monomers, various acryl amides monomers, various alkynol acrylamides and the like. Considering the styrenic monomers (as both a primary monomer in styrene-bυtadiene polymers or a co- monomer in acrylate polymers), they are often referred to as vinyl substituted aromatic compounds (styrenic monomers) and include styrene, alkyl substituted styrene 1- vinylnaplϊthalene, 2-vinyInaphthalene, and the alkyl, cycloalkyl, aryl, alkaryl and aralkyl derivatives thereof in which the total number of carbon atoms in the combined substituents is generally from 8 to about 12. Examples of such compounds include 3- methyl styrene vinyltoluene; alpha-methylstyrene; 4-n-propyl styrene. 4-t-butylstyrene, 4- dodecyl- styrene. 4-cyclohexylstyreπe; 2-ethyl-4-benzylstyrene; 4-methoxy- styrene; 4- dimethylaminostyrene; 3,5-diphenoxystyrene; 4-p-toIyIstyrene; 4-phenylstyrene; 4,5- dimethyl-l-vinylnaphthalene; 3-n-propyl-2-vinyl- naphthalene, and the like. Styrene is preferred,

[0034] The vinyl chloride type monomers include vinyl chloride, vinylidene chloride, and the like. [0035] The vinyl esters can generally be represented by the following formula

_{Formu]a 3}

where R³ is an alkyl generally having from 1 to about 10 or 12 carbon atoms with from about 1 to about 6 carbon atoms being preferred. Accordingly, suitable vinyl esters include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, and the like. Vinyl esters with larger R groups include the vinyl versatate monomers, such as Veo VA-P, Veo Va-IO, and Veo Va-1 1. |00361 The various vinyl ethers can be represented by the formula

H H₂C=CO-R⁴ _{Foπmjla 4}

where R⁴ is desirably an alkyl having from 1 to about 10 carbon atoms. Specific examples include methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, and the like with methyl vinyl ether being preferred. {0037] The acrylonitrile type monomers include acrylonitrile, or methacrylonitrile, or ethacrylonitrile, and the like can be utilized, Acrylamide monomers which can be polymerized to form an alkali sensitive latex copolymer generally have the following formula

wherein R⁵ is H or methyl and R⁶ is generally hydrogen or an alkyl, straight chain or branched, having from 1 to about 18 carbon atoms. Specific examples include acrylamide, ethyl acrylamide, butyl acrylamide, tert-octyl acrylamide, and the like. Unlike the other optional monomers the one or more acrylamides can be utilized in large amounts such as up to about 20 percent by weight of the alkali sensitive latex copolymer and desirably from about 0.5 to about 10 percent by weight. [0038] The alkenol acrylamides can generally have the formula

R⁷ ° H

Formula 6 wherein R⁷ is H or methyl, R⁸ can be hydrogen and preferably is an alkyl, straight chain or branched, having from 1 to about 18 carbon atoms and desirably from 1 to 10 carbon atoms. Specific examples of alkenol acrylamides include methanol acrylamide, ethanol acrylamide, propanol acrylamide, methylol methacrylamide, and the like. [0039] Functionalized acrylamides can also be utilized to increase latex colloidal stability, to enhance latex hydrophilicity, and to improve the durability of the treated paper. Examples of such acrylamides include AMPSO?), i.e., acrylamidotnethylpropane sulfonic acid, DMAPMA, i.e., dimethylaminopropyl methacry amide, and the like. [0040] The polymers from the above one or more alky! (alk)acrylate monomers, styrenc-butadiene monomers, styrene-acrylate monomers, vinyl chloride monomers, vinylidene chloride monomers, and/or vinyl acetate monomers along with at least one unsaturated acid monomer and optionally one or more of any of the less desired above noted monomers can be polymerized by one or more free radical initiators to form one or more different alkali sensitive copolymers of the present invention. Conventionally free radical initiators known to the art and to the literature can be utilized to initiate polymerization of the various above-noted monomers or comonomers to form a polymer or copolymer. Such free radical initiators generally include the persulfates, the peroxides, and azo compounds, as well as redox combinations and radiation sources. Examples of preferred persulfate initiators include potassium persulfate, sodium pεrsulfate, or ammonium persulfate, and the like. The free radical polymerization can be an emulsion, bulk, solution, dispersion, etc., polymerization.

|0041] Generally, any type of peroxide, azo, redox system, or related initiator system can be utilized. Peroxide systems inlude dicumyl peroxide, cumene hydroperoxide, t- butyl perbenzoate, bis(t-butylperoxy) diisopropyl benzene, diisopropyi benzene hydroperoxide and n-butyl 4,4-bis(t-butylperoxy) valerate, as well as benzoyl peroxide, and t-butyl hydroperoxide, and the like. Cumene hydroperoxide, t-butyl hydroperoxide and diisopropyl benzene hydroperoxide are preferred. Azo initiators include 2,2'- azobis(isobutyronitrile)(AlBN) and related azo initiators.

[0042] Alkali sensitive acrylate polymers or copolymers, styrene-butadiene copolymers, vinyl-acetate polymers or copolymers, styrene-acrylate copolymers, vinyl chloride copolymers, vinyiidene chloride copolymers, or vinyl acetate-ethyl ene copolymers can be made by utilizing chain-transfer agents/polymer physical property modifiers. Conventional chain-transfer agents can be utilized such as various mercaptans, for example, thiocthanoi mercaptan, hydroxyl ethyl mercaptan, various reaction products of alkyl esters of mercaptan with acidic acid or with thiogylcolic acid, and the like wherein the alkyl group has from about 2 to about 20 carbon atoms. Another suitable chain transfer agent is beta mercapto propanionic acid and its esters such as butyl-3-mercaptoproρrinate.

[0043] Inasmuch as alkali sensitive latex copolymers are desired, the above noted polymers are generally not crosslinked. However, small amounts of crosslinkable monomers can be utilized such as from about 0.1 to about 10.0 and generally from about 0.3 to 5.0 weight percent based upon the total of all the alkali sensitive latex copolymers utilized. Typically, crosslinking monomers include methylene bisacrylamide and the like. Another class of suitable crosslinking agents is the various diacrylates and polyacrylates such as trimethylol propane triacrylate, pentaerythritol triacrylate, polyallyl compounds such as pentaerythritol tri-allyl ether, and the like.

[0044] The alkali sensitive copolymers of the present invention made from the above noted monomers in order to be suitable for use in the present invention desirably are sensitive to strong alkali solutions, have high, amounts of acid repeat units therein. The alkali sensitive copolymers (irrespective of whether they are a one-component or two- component saturant) are generally sensitive in solutions having a pH of from about 7,0 to about 12, desirably from about 8.0 to about 1 1 and preferably from about 8.5 to about 10. The polymer Tg is desirably less than about 70⁰C, and preferably from about -20⁰C to about 55°C. High Tg values are avoided inasmuch as the polymer is too stiff. While only one alkali sensitive copolymer can be utilized (e.g., a one-component system), it is an aspect of the present invention that blends of two or more such copolymers can be utilized so long as they are compatible with one another (e.g., a two or high component system).

[0045] Recovery of fibers (e.g., paper pulp) can occur in several different manners. One method is to collect unused nonwoven or paper, such as scrap, off spec paper, trims, cut-outs, etc., and/or used paper which has been treated with effective amounts of the alkali sensitive acrylate. styrene-acrylate, styrene-butadiene, vinyl chloride, vinylidene chloride, or vinyl acetate latex copolymer dispersions and place them in a large vat or tank with added water and base. The nonwoven or paper can be pre-shredded to a lesser or greater extent to facilitate addition of the fibers to the tank, stirring, or other handling. The tank can contain any volume but volumes in the amounts of about 4,000 to 5,000 gallons arc common in the industry. Treatment can occur for longer times at ambient temperature or the contents may be heated to a warm temperature such as from about 80⁰F to about 15O⁰F, in another embodiment from about 9O⁰F to about 14O⁰F, and in a third embodiment from about 100⁰F to about 130⁰F. Higher temperatures are avoided. [0046] The aqueous solution is adjusted to a higher pH by the addition of high pH compounds thereto, such as ammonium hydroxide, sodium hydroxide and the like. Target pH values are at least 7.0 or from 8,0 to about 1 1 , and in another embodiment from about 8.5 to about 10. The saturant binder quickly becomes weakened by the alkali solution and is ready to be subjected to mechanical shear. In laboratory tests reported later, the paper to be recycled was blended in a Waring Blender for one to three minutes. It is desired that the tank contain a blender or impeller so that the nonwoven/paper is mixed, agitated, and subjected to shear. The paper and fibers may be allowed to remain in the tank before or after shearing the paper into fibers.

J0047] The material in the tank is used as is as a source/supplement of pulp for papermaking. It contains at various levels of dispersion, e.g., individual fibers with or without saturant/binder thereon along with various other forms of fibers such as small bundles of 2, 3, or 4 fibers connected by saturant/binder. Generally, no attempt need be made to separate any free saturant/binder from the recycled fibers (i.e., any saturant/binder attached to the recycled fibers goes back into the next nonwoven/paper). In one embodiment, it is desirable to blend the recycled nonwoven/paper fibers with virgin fibers. In this embodiment, the fibers going into the paper/noπwoven production process can be from 1 to about 50 weight % recycled fibers (by this process) on a dry fiber basis of the total fibers going into the nonwoven/paper. In another embodiment, the recycled fibers can be from about 5 or 10 to about 30 or 40 weight % of the total fibers in the new nonwoven/paper. In still another embodiment, the recycled fibers are from about 15 to about 30 weight % of the total fibers.

[0048] The benefit of blending virgin fibers and recycled fibers is that if the recycled fibers change any of the physical properties of the finished nonwoven/paper, blending virgin fibers with the recycled fibers dilutes or minimizes those potential changes in physical properties. Lot to lot variation is minimized while utilizing a fiber source that would otherwise be costly scrap.

[0049] The recyclable or repulpable nonw ovens/papers suitable for use in the present invention generally include industrial type paper, such as filtration media; vacuum bags; industrial wipes; book covers; abrasive paper substrates; paper substrates for adhesives, paper wallcoverings; durable paper; tapes; protective masking; decorative paper; crepe tape; label paper; stationary, nonwovens for personal care items, and the like. [0050] The following examples serve to illustrate the invention but not to limit the same. It was desired to develop a family of paper/nonwoven saturants/binders that would exhibit good physical properties but that could be converted to paper/nonwovens that could be recycled. The initial experiments involved adding polymers that were very sensitive to pH changes to conventional paper saturants to see what types and what levels of additives would be needed to allow the paper/nonwoven to be broken down into individual fibers for recycling. Thin films of conventional paper saturants were made. It was observed that addition of polymers very sensitive to pH to conventional saturants made the films weaken upon exposure to pH 10 but not to dissolve. These additizεd paper saturants were then tested to see if such saturants would allow recycling of paper/nonwovens by a simple pH adjustment in combination with moderate to high shear.

[0051] Saturated paper was made from the additized paper saturants. The virgin pulp source was typically a non-saturated cellulose fiber mass called base paper. Three base papers have been used for lab saturation studies. They are characterized by 13.9 lb/1300 ft² (53 g/m²), nominally 5 rails thick, 0.42 g/cm³ density; 13.3 lb/1300 ft² (50 g/m²), nominally 4 mils thick, 0,49 g/cin³ density; or 13.4 lb/1300 ft², nominally 3.5 mil thick. If base paper was to test saturants, the paper could be saturated as received. If base paper was to be blended with recycled paper, both the base paper and the recycled paper were dispersed in water and formed into a hand sheet of similar dimensions and weight to base paper in the laboratory. Generally, it was the intent to add about 25 parts by weight of polymeric saturant for every 100 parts by weight of fibers.

10052] For the purposes of these experiments, if repulped saturated paper was to be used, it was blended with base paper on a 25:75 or 10:90 weight basis based on the weight of the dry fibers. The repulping procedure was to cut the paper to be recycled into small squares and dilute to 2 wt.% solids with water. The pH was adjusted to about 9 with ammonium hydroxide and heated to 130-140⁰F, Then, it was agitated for 1, 2, or 3 minutes in a Waring Blender. Using a standard 12x12 inches lab sheet mold, Handsheets were formed in the laboratory from the repulped material and evaluated for appearance, and then some of these were dried and tested for physical properties. The physical properties of virgin sheets with and without pH sensitive additives were analyzed to determine if the additives were affecting paper physical properties. The physical properties from handsheets from recycled saturated paper were tested. Some of -19-

the saturated paper was just dried to dryness while others were post cured at 300⁰F ( 149°C) to fully activate self-crosslinking moieties in the paper saturant (If present). [0053] When making one-component saturants, the monomers of the high acid content polymers were substituted into the polymerization recipe of conventional paper saturants in comparable amounts to the presence of those monomers in the blends of conventional saturants and the high acid content polymers. These were evaluated for physical properties of the resulting paper and in paper made from repulped saturated paper.

Table Al HYCAR* 2671 Commercial Carboxylated Self-Crosslinking Acrylate Emulsion (Saturant)

First Paper Formed from Base Paper Physical Test Results With Different Levels of a Second High Acid Number Polymer

Level 1 means substituting 5 wt.% of Carboset 5 Ϊ4H for the Hycar 2671 Level 2 means substituting 10 wt.% of Carboset 514H for the Hycar 2671 Level 3 means substituting 15 wt.% of Carboset 5 J4H for the Hycar 2671 Level 4 means substituting 20 wt.% of Carboset 514H for the Hycar 2671 Table A2 HYCAR^® 2671 Commercial Carboxylated Setf-Crosslinking Acrylate Emulsion

First Paper Formed, More Physical Test Results With Different Levels of a Second High Acid Number Polymer

Table A3 HYCAIT >® 2671 Commercial Carboxylated Self-Crosslinking Acrylate Emulsion

Quality of Handsheet from Recycled Fiber Dispersion With Different Levels of a Second High Acid Number Poϋymer

0 No sheet created

S Able to form sheet from recycle, but most paper pieces intact

2 Mixture of fibers and paper pieces

3 Dispersed fibers and a few paper pieces

4 Dispersed fibers and very few pieces and clumps

5 Fully dispersed fibers (no paper pieces) -21-

[0054] These results with Hycar 2671 as a paper saturant illustrate that additions of 10, 15, and 20 wt.% of highly pH sensitive polymer increases the speed and ability to repulp saturated paper into individual fibers and doesn't significantly adversely affect physical properties of the paper.

Table Bl HYCAR ,®^* .26469 Commercial Carbσxylated NOB Self-Crosslinkmg A cry late Emulsion

First Paper Formed Physical Test Results With Different Levels of a Second High Acid Number Polymer

Level I means substituting 5 wt.°/o of Carboset 5 I4H for the Hycar 26469 Level 2 means substituting 10 wt,% of Carboset 514H for the Hycar 26469 Level 3 means substituting 15 wt.% of Carboset 514H for the Hycar 26469 Level 4 means substituting 20 wt.% of Carboset 514H for the Hycar 26469 Tabie B2 HYCAR^® 26469 Commercial Carboxylated Non Self-Crosslinking Acrylate Emulsion

Table B3 HYCAR >®^* .26469 Commercial Carboxylated Non Self-Crosslinking Acrylate Emulsion

Quality of Handsheet from Recycled Fiber Dispersion With Different Levels of a Second High Acid Number Polymer

0 No sheet created

1 Able to form sheet from recycle, but most paper pieces intact

2 Mixture of fibers and paper pieces

3 Dispersed fibers and a few paper pieces

4 Dispersed fibers and very few pieces and clumps

5 Fully dispersed fibers (no paper pieces) [00551 Results for Hycar 26469 indicate the additive does not significantly affect paper physical properties and the additive favorable affects the ability to recycle the saturated paper into individual fibers.

Tabϊe Cl HYCAIT 26469

Latex + 1 Part of Melaraine Formaldehyde Crosslmking Agent

Level 2 means substituting 10 wt.% of Carboset 552 for the {Hycar 26469 + 1 Part of Melamine Formaldehyde Resin)

Level 4 means substituting 20 wt.% of Carboset 552 for the (Hycar 26469 + 1 Part of Melamine Formaldehyde Resin)

Table C2 HYCAI 1T® .26469 Latex + 1 Part of Meiamine Formaldehyde Crossliϋking Agent

Table C3 HYCAR »®^* 26469

Latex + 1 Part Melaimne Formaldehyde Crosslinking Agent

Quality of Handsheet from Recycled Fiber Dispersion

Table D ϊ Hycar® 26469 Latex + 5 Parts Melamine Formaldehyde Crossϊinking Agent

First Paper Formed Physical Test Results With Different Levels of a Second High Acid Number PIymer

Level 2 means substituting 10 wt.% of Carboset 552 far the (Hycar 26469 + 5 Part of Melamine Formaldehyde Resin) Level 4 means substituting 20 wl.% of Carboset 552 for the (Hycar 26469 + 5 Part of Melamine Formaldehyde Resin)

Table D2 Hycar® 26469 Latex + 5 Parts MeJamine Formaldehyde Crosslinking Agent

Table D3 Hycar® 26469

Latex+ 5 Part Melamiπe Formaldehyde Crosslinking Agent Quality of Handsheet from Recycled Fiber Dispersion

Table El 913-620-123 Experimental Carboxylated Non Self-Crosslinking Acrylate Emulsion

Table E2 913-620-123 Experimental Carboxylated Non Seif-Crosslinkiπg Acrylate Emulsion

Table E3 913-620-123 Experimental Carboxylated Non Self-Crosslϊnking Acrylate Emulsion

Quality of Handsheet from Recycled Fiber Dispersion With Different Levels of a Second High Acid NumberPolymer

0 No sheet created

1 Able to form sheet from recycle, but most paper pieces intact

2 Dispersed fibers and paper pieces

3 Dispersed fibers and a few paper pieces

4 Dispersed fibers and very few pieces and clumps

5 Fully dispersed fibers (no paper pieces)

[0056] Results indicate that the saturant/binder can be more easily fractured so that recycling of the fibers is more efficient at higher loadings of the very pH sensitive polymer.

Tabϊe Fl Recycled Fibers from 913-620-123 and Carboset 514H

Saturated and Cured Paper Compare Physical Properties of 100% Recycled

Base Paper with 25% Recycled and Cured 913-620-123 Paper/75% Recycled Base

Paper First Paper Formed Physical Test Results

[0057] The data immediately above illustrates that the use of 25 wt.% recycled fibers from a non self-crosslinking binder saturated paper even after curing at 149°C does not. materially degrade the tensile and other physical properties.

Table Gl 913-620-123 Experimental Carboxylated Non SeH-Crosslinking Acrylate Emulsion

Level 2 means substituting 10 wt.% of Hydrosol 515 for the 913-620- 123 Level 4 means substituting 20 wt.% of Hydrosol 515 for the 913-620- 123

TabIe G2 913-620-123 Experimental Carboxylated Non Self-CrossUnking Acrylate Eulsion

Level 2 means substituting 10 wt.% of Hydrosol 515 for the 913-620-123 Level 4 means substituting 20 wt.% of Hydrosol 515 for the 913-620-123

Table Hl Recycled Fibers from 913-620-123 and Hydrosol 514

Saturated and Cured Paper

Compare Physical Properties of 100% Recycled Base Paper with

10% Recycled and Cured 913-620-123 Paper/90% Recycled Base Paper

Paper Formed Physical Test Results

Table Il Some Test of Hycar 2671, 913-620-104, 913-620-123, and 913-793-105

Table 12

Some Test of Hycar 2671, 913-620-104, 913-620-123, and 913-793-105 Quality of Handsheet from Recycled Fiber Dispersion

-31-

Table Jϊ STYCAR 1168 Latex Commercial Carboxylated Self-Crossiϊriking Styrene-Butadiene Emulsion

First Formed Saturated Paper Physical Properties With Different Levels of a Second High Acid Number Polymer

Level 1 means substituting 5 wt.% of Carboset 514H for the Sfycar 1 168 Level 2 means substituting 10 vvt.% of Carboset 5 I4H for the Sty car 1 168 Level 3 means substituting 15 wt.% of Carboset 514H for the Stycar 1 168 Level 4 means substituting 20 wt.% of Carboset 514H for the Stycar 1 168

Table J2 STYCAR 1168 Commercial Carboxylated Self-Crosslinking Styrene-Butadiene Dispersion

First Formed Saturated Paper, More Physical Properties With Different Levels of a Second High Acid Number Polymer

Tabie J3 STYCAR 1168 Commercial Carboxylated Seif-Crosslinking Styrene-Butadiene Dispersion

0 No sheet created

1 Able to form sheet from recycle, but most paper pieces intact

2 Mixture of fibers and paper pieces

3 Dispersed fibers and a few paper pieces

4 Dispersed fibers and very few pieces and clumps

5 Fully dispersed fibers (no paper pieces)

[0058 j The recycling of crosslinked Stycar polymers is improved by the addition of polymers sensitive to pH. -33-

Tabie Kl 25% Repulped Cured Stycar™ 1168 Latex Sheet Properties

Table Ll VYCAR VA-0450 Commercial Non-Carboxyiated Self-Crossliπking Vinyl-Acetate Emulsion

Formed Saturated Paper Physical Properties With Different Levels of a Second High Acid Number Polymer

Table L2 VYCAR VA-0450 Commercial Non-Carboxyiated Self-Crossllnking Vinyl-Acetate Emulsion

0 No sheet created

1 Able to form sheet from recycle, but most paper pieces intact

2 Mixture of fibers and paper pieces

3 Dispersed fibers and a few paper pieces

4 Dispersed fibers and very few pieces and clumps

5 Fully dispersed fibers (no paper pieces)

-35-

Tabϊe Ml Vycar® 460x45 Latex Commercial Carboxylated Self-Crosslinking Vinyl Chloride Emulsion

Paper Formed from Base Paper Test Results With Different Levels of a Second High Acid Number Polymer

Level 2 means substituting 10 wt.% of Carboset 552 for the Vycar 460x45 Level 4 means substituting 20 wt.% of Carboset 552 for the Vycar 460x45

Table M2 Vycar® 460x45 Latex Commercial Carboxylated Self-Crossϊinking Vinyl Chloride Emulsion

Paper Formed from Base Paper, More Physical Test Results With Different Levels of a Second High Acid Number Polymer

TaWe M3 Vycar® 460x45 Latex Commercial Carboxylated Self-Crosslinking Vinyl Chloride Emulsion

0 No sheet created

1 Able to form sheet from recycle, but most paper pieces intact

2 Mixture of fibers and paper pieces

3 Dispersed fibers and a few paper pieces

4 Dispersed fibers and very few pieces and clumps

5 Fully dispersed fibers (no paper pieces)

Table Nl Vycar® 578 Latex Commercial Non-Carboxyϊated Non Self-Crosslinking Vinyl Chloride Emulsion

Paper formed from Base Paper Physical Test Results With Different Levels of a Second High Acid Number Polymer

Level 2 means substituting 10 wt.% of Carhoset 552 for the Vycar 578 Lovei 4 means substituting 20 wt.% of Carbosei 552 for the Vycar 578 Tabie N2 Vycar® 578 Latex Commercial Non-Car boxylated Non S elf- C ros slinking Vinyl Chloride Emulsion

0 No sheet created

1 Able to form sheet from recycle, but most paper pieces intact

2 Mixture of fibers and paper pieces

3 Dispersed fibers and a few paper pieces

4 Dispersed fibers and very few pieces and clumps

5 Fully dispersed fibers (no paper pieces)

[0059] The non-crosslinked Vycar vinyl chloride polymer seems to result in papers/nonwovcns that recycle very well. The crosslinked Vycar vinyl chloride and vinyl-acetate polymers result in papers/nonwovens that recycle better with the addition of polymers sensitive to pH.

[0060] Modified 913-620- 123, after being soaked in pH 10.0 water for 15, 30 or 60 minutes, films became much weaker (because of modification), both film tensile and % elongation were much lower than un-soaked film. Paper, if saturated with this binder, can be repulpable if soaked in high pH water. While for 913-620-123 control (unmodified), film tensile and elongation were not affected by soaking in high pH water, there were minimum change in film tensile and %elongation.

Table Ol

[00613 While in accordance with the patent statutes, the best mode and preferred embodiment have been set forth, the scope of the invention is not limited thereto, but rather by the scope of the attached claims.

Claims

WHAT IS CLAIMED IS:

1. A method for preparing recyclable fibrous composites, comprising: a) preparing a bonding agent comprising an aqueous addition polymer dispersion characterized by having sufficient acidic functional groups that reduce the physical integrity of a film of polymer derived from drying said bonding agent, but insufficient acidic functional groups in number or strength to promote dissolution of the bonding agent, when exposed to aqueous solutions above pH 7.0; b) combining in any manner a fibrous composite with said bonding agent thereby forming a fibrous composite product bound with the bonding agent.

2. A method according to claim 1 further including a step of drying the aqueous bonding agent forming a polymeric film that bonds some of the interstices of the fibers.

3. A method according to claim 1, wherein said aqueous addition polymer comprises: a) from about 30 to about 70 wt.% repeating units derived from styrene type monomers, from about 29 to about 70 wt.% repeating units derived from an conjugated diene of 4 to 6 carbon atoms, and from 1 to about 7 wt.% repeating units derived from polymerizing acid containing monomer, or b) from about 51 to 98 wt.% repeating units of 4 to 18 carbon atoms from esters of (alk)acrylic acid with monohydric alcohols and from about 2 to about 6 wt.% repeating units derived from an acid containing unsaturated monomer or blends, c) from about 20 to about 99 wt.% repeating units from polymerizing vinyl chloride and/or about 35 to 99 wt.% repeating units from vinylidene chloride and about 1 to about 7 wt.% repeating units from polymerizing acid containing monomer, d) from about 20 to about 98 or 99 weight percent of repeating unites from polymerizing vinyl ester monomers and about 2 to about 6 wt.% repeating units from polymerizing an acid containing monomer, or combinations from a), b), c), and d).

4. A method according to claim 3, wherein said bonding agent comprises a blend of at least two different aqueous addition polymers at least one of which is in the form of a dispersion,

5. A method according to claim 3, wherein said bonding agent consists essential of a single aqueous addition polymer dispersion or latex.

6. A method according to claim 3, wherein the polymeric portion of said bonding agent comprises from about 30 to about 70 wt% of repeating units derived from a styrene type monomer, from about 29 to about 70 wt.% repeating units derived from a conjugated diene of 4 to 6 carbon atoms and from about 1 to about 6 wt.% of repeating units derived from polymerizing an unsaturated acid containing monomer.

7. A method according to claim 6, wherein repeating units from said acid containing monomer is from about 1.4 to about 6 wt.% of said bonding agent on a dry weight (solids) basis.

8. A method according to claim 3, wherein the polymeric portion of said bonding agent comprises from about 70 to about 98 wt.% repeating units with 4 to 18 carbon atoms derived from esters of (alk)acrylic acid with monohydric alcohols and from about 2 to about 6 wt.% repeating units derived from an unsaturated acid containing monomer.

9. A method according to claim 3, wherein said repeating units from an unsaturated acid containing monomer is from about 2.4 to about 4.5 wt.% on a dry weight basis of said bonding agent.

10. A composition comprising a fibrous mat and a polymeric binder, said fibrous mat being in a sheet or roll form and having a thickness of between 25 μm and 25 mm and comprising fibers with a length to diameter ratio of at least five to one, said polymeric^, binder comprising a bonding agent comprising an aqueous addition polymer dispersion characterized by having acidic functional groups that reduce the physical integrity of a film of the bonding agent, but do not dissolve a film of the bonding agent, when exposed to aqueous solutions above pH 7.0.

11. A composition according to claim 10, wherein said aqueous addition polymer dispersion comprises: a) from about 30 to about 70 wt.% repeating units derived from styrene type monomers, from about 29 to about 70 wt% repeating units derived from an conjugated diene of 4 to 6 carbon atoms, and from 1 to about 7 wt.% repeating units derived from polymerizing acid containing monomer, b) from about 51 to 98 wt.% repeating units of 4 to 18 carbon atoms from esters of (alk)acrylic acid with monohydric alcohols and from about 2 to about 6 wt.% repeating units derived from an acid containing unsaturated monomer, c) from about 50 to about 98 or 99 wt.% repeating units from polymerizing vinyl chloride and/or vinylidene chloride and about 1 to about 7 wt.% repeating units from polymerizing acid containing monomer, d) from about 20 to about 98 or 99 weight percent of repeating unites from polymerizing vinyl ester monomers and about 2 to about 6 wt.% repeating units from polymerizing an acid containing monomer, or combinations from a), b), c), and d).

12. A composition according to claim 11, wherein said aqueous addition polymer dispersion comprises from about 30 to about 70 wt.% of repeating units derived from a styrene type monomer, from about 29 to about 70 wt.% repeating units derived from a conjugated diene of 4 to 6 carbon atoms and from about 1 to about 6 wt.% of repeating units derived from polymerizing an unsaturated acid containing monomer.

13. A composition according to claim 1 1, wherein said aqueous addition polymer dispersion comprises from about 70 to about 98 wt.% repeating units with 4 to 18 carbon atoms derived from esters of (alk)acrylic acid with monohydric alcohols and from about 2 to about 6 wt.% repeating units derived from an unsaturated acid containing monomer.

14. A method of recycling fibrous composites comprising: a) preparing a bonding agent comprising an aqueous addition polymer dispersion characterized by having acidic functional groups that reduce the physical integrity of the bonding agent, but do not dissolve the bonding agent, when exposed to aqueous solutions above pH 7.5; b) mixing a fibrous composite with said bonding agent thereby forming a fibrous composite product bound with the bonding agent; c) after said a and b steps optionally drying said bonding agent onto said fibrous composite.