~'T~3ERGLASS NONWOVEN BINDER
The present invention is directed towards binder compositions. More particularly, the present invention is directed towards fiberglass non-woven binder compositions s having at least one carboxy-functional copolymer binder crosslinker and at least one compound capable of forming a hydrogen-bonding complex with the carboxy-functional copolymer binder.
Fiberglass insulation products are generally formed by bonding glass fibers together with a polymeric binder. Typically, an aqueous polymer binder is sprayed onto matted glass fibers soon after they have been formed and while they are stih hot. The polymer binder tends to accumulate at the junctions where fibers cross each other, thereby holding the fibers together at these points. bleat from the hot fibers vaporizes most of the water in the binder. The fiberglass binder must be flexible so that the final fiberglass product can be compressed for packaging and shipping and later recover to its full vertical t 5 dimension when installed.
phenol-formaldehyde binders have lien the primary polymeric binders used in the past in manufacturing fiberglass insulation. These binders are low-cost, easy to apply and readily cured. They provide a strong bond while maintaining elasticity and good thickness recovery so that full insulating value is obtained. Still, phenol-formaldehyde 2o binders release significant levels of forr~naldehyde into the environment during manufacture and therefore constitute an environmental and health risk. Once cured, the resin can continue to xelease formaldehyde in use, especially when exposed to acidic conditions.
As formaldehyde exposure can create adverse health effects in animals and 2s humans, fiberglass binders have been developed that provide reduced emissions of formaldehyde. These developments include a mixture of phenol formaldehyde binders with carboxylic acid polymer binders. Still, formaldehyde emissions remain a concern.
Other formaldehyde-free binder systems have been developed using alternative chemistries. These alternative chemistries have considered three different parts. The first 3o part is a polymer that can be copolymerized with other ethylenically unsaturated monomers, e.g., a polycarboxyl, polyacid, polya~crylic, or anhydride. The second part is a crosslinker that includes an active hydrogen compound such as trihydrie alcohol, triethanolamine, beta-hydroxy alkyl amides or tzydroxy alkyl urea. The final part C
considered for providing a formaldehyde-free birder system is a catalyst or accelerator such as a phosphorous containing compound or a fluomboratc compound.
These alternative binder compositions work well; however, a deficiency of the current cross-linker systems is that they require relatively high temperatures to first drive s off the water and then chemically convert the raw materials to a crosslinked gel.
Temperatures needed to drive this esterification reaction can range 'from about 200°C to about 250°C. Accordingly, there is a need for a fiberglass binder composition that cures at lower temperatures. Fyn~ther, there is a net for alternative fiberglass binder systems that provide the performance advantages of phenol-formaldehyde resins in formaldehyde ~ o free systems.
Polysaccharides such as starch have also been used in binder systems. These polysacebiarides form hydrogen bonding complexes with polyacrylic acid, as well as with themselves. Additionally, these materials can be crosslinked by chemistries known in the art. However, these materials tend to have high molecular weights, which can lead to is clumping and sticking of the glass fibers during processing. As a consequence of this clumping and sticking of the fibers, insulation is produced that can be unfit for commercial use. Accordingly, there is a need for a hydrogen bonding coaoriplex that does not have the disadvamages of the above mentioned polysaccharides.
The binder composition of the present invention provides a strong, yet flexible 2o bond allowing a compressed fiberglass mat to easily expand once compression is released. This binder composition can be a fiberglass non-woven binder composition having at least one carboxy-functional copolymer binder crosslinker and at least one compound capable of forming a hydrogen-bonding complex with the carboxy-functional copolymer binder. In this manner the binder composition is capable of being cwled at 25 lower cure temperatures than with conventional cmsslinkers.
The binder composition can be in the form of an aqueous solution having a polymeric binder and at least one compound capable of forming a hydrogen-bonding complex with the binder. The polymeric binder includes from about 30 to about percent by weight of one or more acid functional monomer units.
3o The binder composition further includes at least one compound capable of forming a hydrogen-bonding complex with the carboxy-functional copolymer binder. In one aspect those hydrogen-banding complex-forming compounds include polysaccharides. It is desirable that the polysaccharides be of low molecular weight so that they form low viscosity solutions, thereby avoiding the problems detailed above.
These polysaccharides have art additional benefit in that they are able to form hydrogen-bonding complexes with themselves. Ftuther, the polysaccharides can crosslink with themselves using techniques well lczrown in the art.
In one aspect, the polysaccharides are starches having water fluidity (' WF') of s about 20 to about 90 can be used as part of the fiberglass binder, (A
description of water fluidity can be found in U.S. Patent No. 4,499,11b.) In another aspect, starches having WF of about 50 to about 90 can be used. In a third aspect, starches having WF
of about 70 to about 90 can be used. In addition, Ivw molecular weight starch derivatives such as dextrins, maltodextrins, corn syrups and combinations thereof can also be used.
According to the invention lower temperature curing can be obtained by using a crosslinker containing a compound capable of forming a hydrogen-bonding complex with the carboxy-functional copolymer binder. This hydrogen-bonding complex forms erosslinks without chemical reaction and therefore can be cured at lower temperatures, e.g,, about 150°C. This results in both energy and time saving during the xnanufaoturiztg is process.
Conventional fiberglass binder systems using triethanol amine compounds are hygroscopic and tend to adsorb moisture in the end-use application In contrast, by using the hydrogen-bonding complex according to the present invention, the novel binder composition overcomes this major problem.
zo 'The present invention is also directed towards a bonded fiberglass mat bonded with a polymer binder composition containing an acid-functional polymer binder and a compound capable of forming a hydrogen-bonding complex with the polymer.
The present invention provides a non-woven bindtr composition having a carboxy-functional polymer and a compound capable of forming hydrogen-bonding 25 complexes with that polymer, The earboxy-functional polymer can be synthesized from one or more carboxylic acid monomers. Iz~ one embodiment, the acid monomer makes up from about 30 to about 100 molt percent of the carboxyl polymer. In another embodiment, the acid monomer makes up from about 50 to about 95 mole percent of the carboxyl polymer. 1n an additional embodiment, the acid monomer makes up from about 30 60 to about 90 mole percent of the carboxyl polymer.
Examples of carboxylic acid monomers useful in forming the polymer of the invention include acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, fumaric acid, malefic acid, cinnamie acid, 2-methyl malefic acid, itaeonic acid, 2-methy itaconic acid, sorbic acid, a ~-methylene glutaric acid, malefic anhydride, itaconie anhydride, acrylic anhydride, methacrylic anhydride. In one aspect, the acid monomor used in synthesizing the polymer is malefic acid, acrylic acid, methacrylic acid or a mixtwe thereof. The carboxyl groups can also be formed tn situ, such as isopropyl esters of acrylates sad methacrylates that form acids by hydrolysis of the esters when the isopropyl group leaves. The carboxylic acid monomer also includes anhydrides that form carboxyl groups i~ situ.
Other ethylenically unsaturated monomers can also be used in forming the carboxyl polymer at a level of up to about 70 weight percent based on total monomer. In another aspect, these ethylenically unsaturated monomers can be used at a level of about 0.1 to about 50 weight percent. These monomers can be used to obtain desirable properties of the copolymer in ways known in the art. For example, hydrophobic monomers can be used to increase the water-resistance of the non-woven"
Monomers can also be use to adjust the glass transition temperature ('Ts') of the carboxyl polymer to meet end-use application requirements. Useful monomers include is but are not limited to (mcth)aerylates, maleates, (meth)acrylamides, vinyl esters, itaconates, styrenics, acrylonitrile, nitrogen functional monomers, vinyl esters, alcohol functional monomers, and unsaturated hydrocarbons.
Low levels of up to a few percent (e.g., up to about 2 weight % based on total monomer) of crosslinking monomers can also tx used iu forming the carboxyl polymer.
This extra crosslinking improves the strength of the bonding. However, at higher levels this can negatively affect the flexibility of the resultant material. The erossli~~king moieties cart be latent crosslinkers. By 'latent crosslinkers' it is meant that the crosslinking reaction takes place not during polymerization, but during curing of the binder.
Chain-transfer agents known in the art can also be used for regulating chain length and molecular weight. The chain transfer agents can be multifunctional whereby star-type polymers can bE produced.
The carboxyl polymer can also be co-synthesized with one or more substituted amide, silanol, or amine oxide tonal monomers for improved glass adhesion.
These 3o functional monomers are used at a level of from about 0 to about 10 percent by vvcight based on tire total monomer. In another aspect the functional monomers arc used at a level of from about O.OI to about 10 percent. In one aspect the functional monomers are used at a level of from about 0.1 to about S percent. Examples of substituted amide monomers include, but are not limited to N-methylol acrylamide, N-ethanol acrylamide, N-propaaol acrylamide, N-methylol methacrylamide, N,N-dimcthyl acrylamide, N,N-diethyl acrylamide, N-isopropyl aerylamide, N-hydroxyethyl acrylamide, N-hydroxypropyl acrylanude, N-octyl aerylamide, N-lauryl aerylamide aad dimethyl aminopropyl (meth)acrylamida 1n one aspect the substituted amide is di-subststuDed, e.g:, s N,N-dimethyl acrylamide and N,N-diethyl xcrylamide.
Examples of silanol monomers include vinyl trisisopropoxy silane, vinyl trisethoxy silane, vinyl trlsmethoxy silane, vinyl trls(2-methoxyethoxy) silane, vinyl methyl dimethoxy silane, y-mcthacryl oxypropyl trimethoxysilane and vinyl triaeetoxy silane. These monomers ate typically copolymerized with acrylic acid in wator.
They to hydrolyze in situ to form the silanol linkages and liberate the corresponding alcohol, which can then be distilled off.
The amine oxide monomers are typically incorporated by copolymerizing an amine-containing monomer, e.g., 2-vixiyl pyridine, 4-vinyl pyridine, dimethyl aminoethyl methacrylate, and then oxidizing the amine functionality to the amine oxide.
The amine l5 can also be oxidized to amine oxide prior to polymerization.
Similarly, the substituted amide and silanol funcdonalities can be introduced into the carboxyl polymer by other mtans. For example, the silanol functionality can be incorporated by using a chain transfer agent such as y-mereaptopropyl trimethoxy silane.
Also, a polymer containing acrylamide groups can be functionalixed, for example, with 2o dimethyl amine to give a substituted amide derivative. Copolymers of amino acids, such as a copolymer of aspartic acid and sodium aspartate as disclosed in U.S.1'atant Number 5,981,691, are useful. These polymers contain amide functionality in the backbone (e.g., Reactin AS 11 from Folia, Inc., Birmingham, Alabama). Furthermore, these copolymers have imide funcdonality. This imide functionality can be reacted with art amine reagent 25 such as di-ethanol amine to form a polymer with amide side chains.
A carboxyl polymer can further be formed from the hydroxyl group of amine monomers as described in U.S, Patent Publication Number 200410082240. Those amine monomers provide an internal cmsslinlcer and partially or fully eliminate the need for additional crosslinket. The binder composition can also be formulated with erosslinker(s) 3o typically used in fiberglass binder compositions, such as hydroxyl, polyol, or araine components. Useful hydroxyl compounds include, but era not limitod to;
trihydric alcohol; ~-hydroxy alkyl amides; polyols, especially those having molecular weights of less than 10,000; ethanol amines such as triethauol amine: hydroxy alkyl urea;
and oxazolidone. UseRii amixles include triethanol amine, dicthylene triamine, tetratGthylene _5.
pentarnine, and polyethylene imine. In addition to providing additional crosslinking, the polyol or amine also serves in plasticizing the polymer film.
The carboxyl polymer can be synthesized by known polymerization methods suds as solution, emulsion, suspension and Inverse emulsion ~lymerization methods.
In one embodiment, the polymer is formed by solution polymcrixation in an aqueous medium, The aqueous medium can be water or a mixod water/water-miscible solvent system such as a water/alcohol solution. The polymerization cats be batch, sari-batch, or continuous.
The polymers are typically prepared by free radical polymerization; however, condensation polymerization can also be used to produce a polyrnscr containing the io desired moieties. The monomers can be added to the initial charge, added on a delayed basis, or a combination.
In one embodiment, the carboxyl polymer is formed at a solids level in the range of about 15 to about 60 peroctst. In another embodiment, the polymer is formed at a solids level in the range of about 25 to about 50 percent.
In one embodiment, the carboxyl polymer can have a pH in the range of from about 1 to about 5. In another embodiment, the polymer can have a pH in the range of about 2 to about 4. Preferably, the pH is greater than 2 for the hazard classi$cation it vSrill be afforded.
The carboxyl polymer cars be partially neutralized, which is commonly done with 2o sodium, potassium, or ammonium hydroxides. However, it is not necessary to neutralize the carboxyl polymer. The choice of base and the partial-salt formed affects the glass transition temperature ('T$'~ of the copolymer. The use of calcium or magzsesiutn base for neutratizadon produces partial salts having unique solubility characteristics, making them quite useful depending on end-use application.
2s The carboxyl polymer may be random, block, star, or other known polymer architecture. Random polymers are preferred due to the economic advantages;
however other architectures could be useful in certain end-uses. Copolymers useful as fiberglass binders have weight avers;e molecular weights in the range of about 1,000 to about 300,000. In anc aspect, the weight average molecular weight of the copolymer is in the 3o range of about 2,000 to about 15,000. In another aspect, the wtight average molecular weight of the copolymer is in the range of about 2,500 to about 10,000. In one aspect, the weight average molecular weight of the copolymer is in the range of about 3,400 to about 6,000.
The binder composition of the invention also contains compounds capable of forming hydrogen bonding complexes with the carboxyl polymer. This allows for crosslinking at lower temperatures. These cmsslinking compounds can be used in conjunction with the functional copolymers of the presont invention, but are also used with polymer and copolymezs currently used as fiberglass binders. They can also be used in combination with the conventional crosslinking compounds listed prc°viously.
Examples of hydrogen-bonding eomplexing agents include, but are not limited to polyslkylene glycol, polyvinyl pyrrolidone, polysaccharides, polyethylene amine, or mixtures thtreof. In orse embodiment the polyalkylene glycol is polyethylene glycol.
t o Polysaccharide that can be useful in the present invention can be derived from plant; animal and microbial sources. Examples of such polysaccharides include starch, cellulose, gums (e_g., gum arabic, guar and xanthan), alginates, pectin and gellan.
Starches include those derived from maize and conventional hybrids of maize, such as waxy maize and high amylose (greater than 40"h amylose) maize, potato, tapioca, wheat, is rice, pea, sago, oat, barley, rye, amaranth including conventional hybrids or genetically engineered materials.
Also included are hemicellulose or plant cell wall polysaccharides such as ~
xylans. Examples of plant cell wall polysaccharides include arabino-xylans such as corn fiber gum, a component of com fiber. An important feature of these polysaccharides is 2o the abundance of hydroxyl groups. These hydroxyl groups provide sites for crosslinldng.
Some polysacchacidea also contain other functionality such as carboxyl groups, which can be ionically crosslinl~ed as well. Amylose containing starches can associate through hydrogen bonding or can complex with a wide variety of nnaterials including polymers, The polysaccharides can be modified or derivatizcd by ctherification (e.g., via 25 treatment with propylene oxide, ethylene oxide, 2,3-epoxypropyltrimethylammonium chloride), esterification (for example, via reaction with acetic anhydride, oetenyl succinic anhydride ('4SA')), acid hydrolysis, dextrinization, oxidation or enzyme treatment (e.g., starch modified with a-amylase, ~-amylase, pullanase, isoamylase or glucoamylase), or various combinations of these treatments.
Other polysaccharides useful hydrogen-bonding materials include maltodcxtrins, which are polymers having n-glucose units linked primarily by a-1,4 bonds and have a dextrose equivalent ('DE') of less than about 2Q. Maltodextrins are available as a white powder or concentrated solution and are prepared by the partial hydrolysis of starch with acid andlor enzymes.
Polysaccharides have the additional advantage of forming hydrogen bonding complexes) with themselves. Accordingly, tha binder composition can include the polysaccharides) without the carboxyl polymer. 'This polysaccharide can be further crosslinkcd using crossiinking agents known in the art. Such crosslanking agents include s but are not limited to phosphorus oxychloride, epichlorohydrin, sadiutn trimetaphosphate, or adipic-acetic anhydride.
The hydrogcn~bonding complex to polymer binder weight xatio is from about 1:99 to about 99;1. In one aspect the hydrogen-bonding complex to polymer hinder weight ratio is from about 1 ~0 to about 20:1. ~ another aspect the hydrogen-bonding catnplac to polymer binder weight ratio is from about 5: 1 to about 1:5.
The binder composition can form strong bonds without the need for a catalyst or accelerator. One advantage of not using a catalyst in the binder composition is that catalysts tend to produce films that cast discolor and/or release phosphorous-containing vapors. An accelerator or catalyst can be combined with the copolymer binder in oz~der to is decrease the cure time, increase the crosslinking density, and/or decrease the water sensitivity of the cured binder. Catalysts useful with the binder are known in the art, such as allcali metal salts of a phosphorous-containing organic acid, e_g., sodium hypophosphate, sodium phosphate, potassium phosphate, disodium pyrophosphate, tetrasodium pyrophosphate, sodium tripolyphosphate, sodium hexamctaphosphate, 2o potassium polyphosphate, potassium tripolyphospate, sodium trimetaphosphate, sodium tetrametaphosphate; fluoroborates, and mixtures thereof. The catalyst could also be a Lewis acid, such as magnesium cattate or magnesium chloride; a Lcwis bast; or a fret radical generator, such as a peroxide. The catalyst is present in the binder formulation at from Q to 25 percent by weight, $nd more preferably from 1 to 10 percent by weight 25 based on the copolymer binder.
The carboxyl polymer, compound capable of forming hydrogen-bonding, and optional catalyst are blended together to form a f bcrglsss binder composition.
The binder composition can optionally be formulated with one or more adjuvants such a5 coupling agents, dyes, pigments, oils, fillers, tl~ert~nal stabilizers, emulsifiers, 3o curing agents, wetting agents, biocides, plasticizers, anti-foaming agents, waxes, enzymes, surfactants, release agents, corrosion inhibitors, additives to t:ninimiu leaching of glass, flame-retarding agents, and lubricants. The adjuvants are generally added at levels of less than 20 percent based on the weight of the copolymer binder.
-g_ The poiymer binder composition is useful for bonding fibrous substrates to form a formaldehyde-free non-woven material. The copolymer bitader of the invention is especially usefirl as a binder fox heat-resistant non-wovens, e.g., aramid fibers, ceramic fibers, metal fibers, polyrayon fibers, polyester fibers, carbon fibers, polyimide fibers, and mineral fibers such as glass fibers.
The copolymer binder composition is generally applied to a fiber glass mat as it is being formed by means of a suitable spray applicator, The spray applicator aids in distributing the binder solution evenly throughout the formed fiberglass mat.
Solids are typically present in the aqueous solution in amounts of about 5 to 25 percent by weight of 1o total solution. The binder may also be applied by other means known in the art, including, but not limited to, airless spray, air spray, padding, saturating, and roll coating.
Residual heat from the fibers volatiz~es water away from the binder. The resultant high-solids binder-coated fiberglass mat is allowed to expand vertically due to the resiliency of the glass fibers. The fiberglass mat is then heatod to cure the binder.
is Typically, curing ovens operate at a temperature of from 130°C to 325°C. However, the binder composition of the present invention can be cored at lower temperatures of from about 110°C to about 1 SO°C. In one aspect, the binder composition can be cured at about 120°C. The fiberglass mat is typically cured Exam about 5 seconds to about 15 minutes.
In one aspect the fiberglass mat is cured from about 30 seconds to about 3 minutes. Tlte 2o cure temperature anti aura time also depend on both the temperature and level of catalyst used. The fiberglass mat can then be compressed or rolled for shipping. An important property of the fiberglass mat is that it returns substantially to its full vertical height once the compression is removed. The copolymer binder produces a flexible film that allows the fiberglass insulation to bounce back when the roll is unwrapped and placed in walls z5 andlor ceilings.
Fiberglass or other non-woven treated with the copolymer binder composition is useful as insulation for heat or sound in the form of rolls or baits; as a reinforcing mat for roofing and flooring products, ceiling tiles, flooring tiles, as a mieroglass-based substrate for printed circwit boards and 'battexy separators; for filter stock and tape stock and for 3o reinforcements in both non-cementatious and cementatious masonry coatings.
The following examples are presented to further illustrate and explain the present invention and should not be taken as limiting in any regard.
E~,1~PLE 1 The following farmulataons ware mined together to form insulation sizing resins.
50 grams of a 50% solids solution of polyacrylic acid was blended with 26 grams of 50°l0 solutions of the listed crossliaker producing 7f> grams of a 50% solids nonwovezt binder s composition. Curing was measured by qualitatively measuring the strength of the resulting film.
The testing protocol was as follows, 20 grams of each of solution was poured into PMP petri dishes and placed vverniglat in a forced air oven set at 60°C. The film was then cured by being placed fox 10 minutes in a forced air oven set at 150°C. After 1 o cooling, the cure of the resulting films was evaluated in terms of physical appearance, flexibility, and tensile strength.
FacampiaAmount co-ingredientAmount Performance of # of of insulation polyacrylic co-ingredientsizing re:in acid i5o96 solution 1 a 50 Triethanol 13 Control (cured amine at 220C) nom bve _ 50 Polyethylene 13 Cured better compared 1 b glycol to 800 conventional main in 1a 1 c 50 Polyethylene 13 Cured better compared glycol to 6000 conventional resin in is id 50 Polyvinyl 10 Cured better compared pyrrolidone to conventional resin in 1 a _ 50 Polyethylene 10 Cured better compared 1e amine to conventional resin in 1a While not being bound by any theory, it is bolieved that the resins in lb to 1e form 15 hydrogen bonding complexes. Hence, they cure at much lower temperatures than the conventional resin in la. This is because the conventional resin needs to undergo an esterification reaction beivvecn the polyacrylic acid and the TEA after all the water in the system is driven off. In contrast, after driving the water off in 1b to lc, hydrogen-bonding complexes are formed, which lower energy costs and save processing time:
F.X,AMPLE 2 Copolymer binders containing glass-adhesion promoting comonomers were synthesized as follows --A reactor containing 200 grams of water and 244 grams of isopmpanol was heated to 85°C. A monomer solution containing 295 grams of acrylic acid and 4.1 grams of N,N-dimethyl acrylamide was added to the reactor over a period of 3.0 hours.
An initiator solution comprising 15 grams of sodium persulfate in 100 grams of deioniud water was simultaneously added to the reactor over a period of 3.5 hours. The reaction product was held at 85°C far an additional hour. The isopropanol was then distilled using a Dean-Stark trap.
is ~ 2B
A reactor containing 200 grams of water and 244 grams of isopropanol was heated to 85°C. A monomer solution containing 295 grams of acrylic acid and 5 grams of vinyl trisisopropoxy silane (available as CoatOSil~ 170b from GE Silicones, Wiltvn, Connecticut) was added to the reactor over a period of 3.0 hours. An initiator solution 2o comprising of 15 grams of sodium persulfate in 100 grams of deionized water was simultaneously added to the reactor over a period of 3.5 hours. The reaction product was held at 85°C for as additional hour, Tho isopropanol was then distilled using a Dean-Stark trap. The isopmpdxy silane is attached to the copolymer via the vinyl linkage.
I~owever, it hydrolyzes during the reaction forming silanol groups and isopropanol. The 2s isopropanol formed is distilled with the rest of tl~ isoprapanol added to the initial charge.
Additional water is added to the reaction to dilute it to 50% solids.
A reactor containing 200 grams of water and 244 gams of isopmpanol was heated 30 tv 85°C. A monomer solution containing 295 grams of acrylic acid and 5 grams of vinyl triethoxy silane (available as Silquest~ A 151 from GE Silicones, Wilton, Gonnecticut) was added to the reactor over a period of 3.0 hours. An initiator solution comprising of grams of sodium persulfate in 100 grams of deionized water was simultsaeously added to the reactor over a period of 3.5 hours. The reaction product was held at 85°C for an additional hour, The isopmpanol was then distilled using a Dean,Stark trap.
The isopmpoxy silane is attached to the copolymer via the vinyl linkage. ~Iowever, it hydrolyzes during the reaction to form sila~tol groups and ethanol. The ethanol formed is distilled with the rest of the isopropanol added to the inititat charge.
Additional water is s added to the reaction to dilute it to 50 percent solids.
A reactor containing 200 grams of water and 244 grams of isopropanol was heated to 85°C. A monomer solution containing 295 grams of acrylic acid and S
grams of 4 t 0 vinyl pyridine was added to the reactor over a period of 3.0 hours. An initiator solution comprising of 15 grams of sodium persulfate in 100 grams of deioni~ed water was simultaneously added to the reactor over a period of 3.5 hours. The reaction product was held at 85°C for an additional hour. The isopropanol was then distilled using a Dean-Stark trap. The vinyl pyridine moiety was then oxidized to amine oxide by treating tl~e polymer ~ 5 with hydrogen peroxide in the presence of sodium molybdate.
Solutions were prepared by dissolving 25 gxams of a polyecrylic acid (available as Alcosperse~ 602A from Alco Chemical, Chattanooga, Tennessee), and a low viscosity 2o starch solution in the amount detailed in Table 2 below. The solutions were diluted to 10%, and the viscosities of these 10% starch-containing solutions were measured. As a comparison, the viscosity of a similar solution containing triethanol amiae (a conventional crosslinker known in tho art) was also measured, ExamploCrosslinking agent rams of orosslinkingscosity WF of of a agent added 10% fiberglassstarch to polyacrylic sizing solution avid solution 3a Triethanol amine 4.3 18 ' -3b Acid corwerted waxy28.9 19.7 85 mafiz!
substituted with hydroxypropyl rou 30 % solids 3c Ac converted waxy 18 19.6 85 maize substituted with hydroxypropyl rou 50 % solids 3d Acid converted waxy2fi.8 18.8 Bknd mane of octenyl svccinabe 40 WF
I waxy maize dextrin blend (30% g~mh solids) and dextrin p~ ~n~~ ~y ~~ 1g 20.8 Blend of octenyi succinate 40 WF
I waxy maize dextrin blend (5096 $~~h solids]
and dextrin 3f AGd converted waxy 16 _ B3 maize 20.0 octen I succinate 50% solids 3g Beta amylase converted16 16.5 85 waxy m8ize octenyl succinate (50%
solids 3h Acid converted waxy28.9 45.3 40 mains substituted with hydroxypropyl rou s 30 % solids 3i Regular high molecular3 2000 5 weight starch The data indicate that the viacosities of the starch/polyacrylic acid solutions with water fluiditics ('WF') from 40 to 85 are in the range of the viscosity of the conventional polyacrylic acid-triethanol amine system, However, a traditional unmodified starch has a very high viscosity and cannot be used in this system.