NL7810366A - METHOD FOR MANUFACTURING PAPER - Google Patents

Description

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The B.F. Goodrich Company, Akron. Ohio, United States of America.

Method of manufacturing paper.

Sheet-shaped paper products are made from all kinds of fibers using the "fat-laid" method on paper machine-type equipment, where the fibers are ground in water in a hollander and the resulting fiber suspension is applied to a moving sieve, where 5 the water is sucked out of the fibers and the screen, which carries the wet fiber mat, is passed over one or more drying rollers and / or the wet fiber mat is transferred to a felt, that it is placed over the drying rollers arranged behind it and / or wear the finishing equipment arranged behind it. As a rule, high-strength, long-fiber cellulose pulp is used to make strong fabrics and paper. However, it is increasingly desirable to use low-grade pulp and / or wood pulp for papermaking, and it is increasingly desirable to make papermaking requiring high strength or other special chemical and / or physical properties. In such cases, a binder is incorporated into the fibers before or during the formation of the web. Many types of non-cellulose fibers, such as ceramic fibers and / or synthetic textile fibers, generally require the use of a binder because of the low adhesion between the fibers in the wet or dry fiber mat. Usually quite long Hollander times are required without binder to achieve a desired tensile strength for the sheet, and the really high tensile strengths required for many applications are not achieved without binder addition.

The "fat-laid" method of papermaking, in which binder latices or coagulated binder latices are added in the Hollander in the form of a suspension of binder particles, has caused all kinds of problems. Direct addition of binder latices in the Hollander usually involved the Dutchman adding a solution of papermaker's alum or other salt-type coagulant, after which the binder latex was added The coagylate, which is "caught" in the fibers after such a procedure, is often too soft and sticky. so that binder contaminates the sieve and felts of the paper machine and 7810366

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"2 and often the binder is not distributed homogeneously in the fibers. Often too much fiber and binder material is lost in the witvater of the wet screen area of the machine and presents major problems in recovery. Other salt-type coagulants are already known, such as, for example, the combination of sodium citrate and sodium lignosulfonate, which is proposed in U.S. Pat. No. 2,759,813. These known coagulant systems use some metal salt and suffer from the same problems as alum. All such coagulants yield paper contaminated with salt type residues, which often cannot be tolerated in the final paper product. For example, ceramic papers used as support for combustion catalysts in automobile exhaust converters must be free of alum to avoid catalyst deactivation and short converter life.

Additives have been used to improve the treatment in the Dutch. For example, in U.S. Pat. No. 3,7 ^ 8,223 there is a better retention of the solids from the binder latex in that an anionic water-soluble polymer, such as polyacrylic acid or its salt, is added to the binder latex before it is added in the hollander. added. This method has the drawback that the binder latex becomes less stable and, furthermore, the method is not generally applicable. US Pat. No. 3,861 + .288 states that the quaternized polymers of epihalohydrin polymers could be used as "additives for paper and non-textile fabrics", but for what purposes it is not entirely clear.

U.S. Patent Application Serial No. 573,977 discusses adding in the Hollander a water-soluble anionic polymer or its salts of acrylic acid to asbestos fibers so that the grinding degree "Canadian Standard Freeness" (hereinafter referred to as "CSF") is controlled or set. The latter addition is believed to involve the underline action of the anionic polymer and ions on the normally cationic surface of the asbestos fibers. With the exception of asbestos, many of the said and other additives with known coagulation with alum of the binder latex were used.

According to the invention, an improved method of papermaking has been found, with which better papermaking products are obtained. In such a process, binder latices are added directly into the wood along with an ionic binder coagulation system, which operates without metal-type impurities. The novel ionic coagulation system of the invention utilizes polycationic and polyanionic polymeric additives with opposite electrical sign of the ions. First, the fibers in the hollander are rendered cationic by the addition of the polycationic additive to attract the binder, and then the polymeric additive is added so that the binder latex solids are destabilized and an ionically controlled binder deposit is deposited. the fibers of the cargo are brought about in the hollander.

The method of the invention comprises adding three essential polymeric additives in the Hollander in the following order only: 1) an aqueous solution or dispersion of a polycationic hydrophilic, water-soluble or dispersible quaternary salt of a polymer that polymer-bonds quaternizing groups belonging to halide and monoamino groups; (2) a binder latex and (3) an aqueous solution of a polyaminionic hydrophilic, water-soluble polymer belonging to the carboxylic and alkali metal, ammonium and amine salt forms of a polymerized acrylic acid. Only after the third of said three additives has been added does the milky charge become clear because the binder latex solids deposit on the fibers in an orderly, controlled manner. The batch can then be transferred to the wet screen section of a paper machine, where the binder-containing batch is turned into a web and the web is dried to provide paper.

It has been found that the total Dutch time for obtaining paper with a certain tensile strength in the dry state is markedly shortened and that it is possible with the aforementioned system of additives to obtain paper with a very high tensile strength in the dry state in shorter Holland times. than with already known methods, in which coagulants of a metal salt type are used.

Furthermore, the ionic coagulation system of the invention makes the charge much less critical of the pH in the case of most fibers, and in particular of cellulose fibers. Indeed, the total system of 7810366 * k additives as such has a relatively small effect on the charge pH, whatever the natural or starting pH of the original fiber slurry and binder latex. This relative insensitivity to pH effects makes it possible to use binder latices, which have a wide range of native pH, ranging from sheet 9 * 5 to rather acidic binder latices with a pH of only 3 or U or even lower.

Furthermore, the final sheet papers obtained, which are made by the process of the invention, are relatively free of metal salt type impurities and have better physical properties, such as better stability and better chemical, electrical and other properties. .

With the method of the invention, losses of solids in the witvater (serum) are considerably reduced and the losses, which still exist, are easily recycled into the hollander in the process without any adverse effect. It is believed that any additives remaining in the witvate interact in some way ionically, so that returning them in the process has little ionic or pH effect on the next batch, those with water, including in the process returned witvater, is made.

Although it is not intended to be bound by any theory, it seems that deposition of the polycationic additive on the fibers makes it much more susceptible to the binder solids. Normally, it is difficult to cause the ionically neutral to anionic fibers of the invention to absorb typical binder solids by any mechanism other than physical scavenging when the binder solids are freshly coagulated and have a soft, tacky surface . Therefore, the distribution of binder in paper made by salt coagulation methods is generally not homogeneous. In the process of the invention, the last additive, ie the polyanionic polymer, does not seem to suddenly cause a phase reversal of the dispersed in the undispersed state, as is the case with the known salt coagulants -type. Rather, the deposition of the binder after the addition of the third or polyanionic additive is a gradual deposition of binder on the fibers as if mixing the polyanionic material with the dispersed 781036®% 5 fibers causes the polyanionic coated fibers to attract the mixture. .

The method of the invention can be applied to natural and / or synthetic fibers with a surface which is neutral to anionic in nature. Fibers of this category include cellulose fibers, which are usually nearly neutral in nature and which, when watered in Water, generate at least a slightly alkaline aqueous phase; glass and ceramic fibers, which are essentially ionically neutral for all applications and purposes; the synthetic textile fibers, such as nylon, polyesters and acrylic fibers, which are also essentially ionically neutral in water; and other naturally occurring fibers, such as those of leather, cotton, linen and full. The method can be used in particular in the case of glass and ceramic fibers, but its greatest use may be in cellulose fibers and in particular in the least grades of paper pulp, which may contain greater or lesser levels of wood pulp.

Polycationic additive

In the process of the invention, hydrophilic, water-soluble or dispersible polymeric quaternary salts obtained by a polymer containing a polymer-bound quaternizing group such as halide or monoamine groups can be reacted with a suitable quatemizing agent, such as tertiary monoamines and organomonohalides. As a rule, about 1-5 moles of the quaternizing agent per mole of polymer-bound quatemizing group in the polymer are used if the quaternary salt is formed in solution 25 and at most about 25 moles of substance per mole of polymer-bonding quatemizing group may be required when the major reaction is carried out. The quateraized polymer should contain at least 10, preferably at least 5, and most preferably at least 90, polymer-bonded quaternizing groups which have been converted into quaternary salt. The quaternizing reaction is usually conducted at temperatures of 50 -120 ° C, and preferably from 60-100 ° C.

A preferred group of polycationic additives are quaternary salts belonging to quatemized polymers, which provide 50-100 wt.% Of a combined epihalohydrin and up to 50 wt. 2 "7" contains and quaternized polymers containing 50-100 parts by weight of a combined monoaminoalkanol ester of an acrylic acid and up to 50% by weight of one or more non-amino monovinylidene monomers.

A more preferred polycationic additive is a quaternized polymer containing 60-100 wt.% Of an epihalohydride and at the most of a mono-epoxy monomer having the structure HCl -CH2-2/2 such as an alkylene oxide.

The epihalohydrin polymers that can be used in the process of the invention are prepared by using a monomeric material

,. . H C_CIL-CHJC

Sew that an epihalohydrin of the structure 2/2/2 wherein X is a halogen atom such as fluorine, chlorine, bromine or iodine. Much more preference is given to epihalohydrin monomers of said structure, wherein X is chlorine or bromine. From the point of view of price and availability, epichlorohydrin is most preferably used.

Other halogen-containing epoxide monomers which can be used as a partial replacement of up to 30-40% by weight of the epihalohydrin include H-chloro-1,2-epoxybutane, lt-bromo-1,2-epoxybutane 1- (1,3-dichloroisopropoxy) -2,3-epoxy-propane, 1-bromoethylglycidyl ether and many others.

Epihalohydrin copolymers which can be used in the process of the invention include those which are approximately 50-100 wt.% Of a combined epihalohydrin and up to 50 wt.% Of one or more halogen-free mono-epoxy monomers containing said structure, such as, inter alia, alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, octylene oxide and others; cycloaliphatic oxides, such as cyclohexene oxide, vinyl cyclohexene oxide, and others; glycidyl ethers, such as methyl glycidyl ether, ethyl glycidyl ether, and many others; aromatically substituted alkylene oxides, such as styrene oxide, and others. Preferred halogen-free epoxy monomers are the alkylene oxides of 2-8 carbon atoms. Most preferred is ethylene oxide.

The polycationic additive should be from a polymer having an average molecular weight of about 5000 to up to 200,000 or more before quaternization. Such a molecular weight can be achieved by direct polymerization and also, as far as epi- 7810366 is concerned. 7 halophaydrine polymers of such molecular weight, which are obtained by slightly crosslinking a polymer of lower molecular weight, by reaction with a polyamine, as described in U.S. Pat. No. 3,886,288. This patent contains detailed information about monomers, polymers and their preparation, as well as about the cross-linking and quaternization reaction and reactive components.

As is known, the quaternization reaction sometimes results in a certain loss in molecular weight of the starting polymer, depending on the time (in particular), temperature and other conditions used in the quaternization reaction. Such a loss in molecular weight is not important in the higher molecular weight polymers, but may be this sheet in the lower molecular weight polymers, since it is not carefully folded.

The best and cheapest results are achieved here with poly-15 cationic materials, relative to original polymers, from 10,000 to 25,000 or slightly higher.

As has already been mentioned, the quaternary salts of polymers of a monoaminoalkanol ester of an acrylic acid are effective and very useful in the practice of the invention. Such polymers are prepared by a monoaminoalkanol ester of an acrylic acid, alone or together with one or more not -amino monovinylidene monomers having the structure ΟΟ ^ ΟΟ, such as, inter alia, alkyl esters of an acrylic acid, such as ethyl acrylate and methyl methacrylate, vinyl acetate, aerylonitrile, styrene, vinyl chloride, vinylidene chloride and others. The polymers should contain about 50-100 parts by weight of the aminoalkanol ester and at most about 50 parts by weight of the non-amino monomers. When more than about 50 parts by weight of the comonomer is added, the efficiency of the transfer becomes less. The polymers are quaternized by reaction with an organomonohalide containing less than 5 carbon atoms, such as ethyl chloride, ethyl bromide, propyl bromide, butyl bromide, and others.

As the polycationic material, the polymeric quaternary salts which are obtained by reacting a tertiary monoamine with a polymer of vinyl or vinylidene chloride can also be used. Binder latex 35 Any synthetic polymer latex may be used as bindmi ddellat ex in the practice of the invention. For example, the binder can be a latex of any resinous or rubbery or elastomeric polymeric material, including homopolymers and copolymers of two or more of vinyl chloride, styrene, vinyl acetate, vinylidene chloride, aerylonitrile, acrylic esters, conjugated dienes, chloroprene, and many others. Particularly suitable are latices of rubbery alkyl acrylate polymers, such as that of ethyl acrylate with no other comonomers, and with or without built-in curing sites and / or self-curing properties. Another particularly suitable category of binder polymers are the co-10 polymers with 1 + 5-90% by weight of combined butadiene-1,3 and 10-55% by weight of combined aerylonitrile, and these are oil resistant synthetic rubbers. Similar copolymers of butadiene and styrene (type SBR) are another type of rubber latex that can be used when oil resistance is not required. The butadiene-derived binder elastomers can terminate in carboxyl to give the binder additional hydrophilicity and / or other special properties to the fiber web.

Excellent results are achieved with many acrylic polymers, which are self-curing or with chain gaps containing a small number of monomer units, which can serve as a curing site.

Particularly preferred self-curing acrylic materials are copolymers of an alkyl acrylate ester in which the alkyl group contains at most 8 carbon atoms, at 0.5-20 parts by weight, and preferably 0.5-10 parts by weight. of one or more acrylamide monomers, such as acrylamide, methacrylamide, tert-butyl acrylamide, and others; the N-alkylolamides of an acrylic acid, such as N-methylolacrylamide, N-methylolmethacylamide, and others; N-alkoxyalkylacrylamides, such as N-ethoxyacrylamide, N-ethoxymethacylamide, and others. Such self-curing acrylic materials can contain one or more other monovinylidene monomers such as aerylonitrile, methyl methacrylate, styrene, vinyl acetate and many others. Self-curing acrylic materials should contain about 55-80 wt.% Of the alkyl acrylate, including monomers in the stated concentrations of the self-curing material and any residual 25-41 + / v. one or more monovinylidene monomers, as already mentioned.

Other curable acrylic binders that can be used are acrylic copolymers which contain curing sites at intervals in their chain and which are reactive with an added curing agent. Such copolymers contain about 55-90 wt% of one or more alkyl acrylate esters, wherein the alkyl group contains up to 8 carbon atoms, and about 0.2-10 wt%, more preferably about 0.2-5 wt%, of 5 a halogen-containing monovinylidene monomer such as 2-chloroethyl vinyl ether, vinyl benzyl chloride and others. All acrylic materials of this type can be monomer mixtures, which are incidentally similar to those of the aforementioned self-curing acrylic materials.

Preferred binder agents are those which are ionically neutral or anionic in nature and have a latex pH of about 4-8.

Polyanionic additive

The polyanionic additive is based on a polymer of an acrylic acid with an average molecular weight not below about 10,000 and preferably above about 2,000,000. Polymers with an average molecular weight between about 80,000 and 200,000 are preferred.

The polyanionic additive can be any polymer of an acrylic acid with up to 5 carbon atoms, such as acrylic acid, methacyl acid or ethacrylic acid.

The polyanionic additive may consist of the non-neutralized carboxylic acid form or its partially or completely neutralized salt forms, wherein the base is an alkali metal hydride, a monoamine or ammonium hydroxide. The carboxylic acid form of the polyanionic additive is most preferably used because there are no metal salt residues. Polyacrylic acid solutions with 10-50 wt% solids in total have a pH of 2-3 · Eat more or less completely neutralized sodium salt of polyacrylic acid in similar concentrations in water, but shows a pH of 7-9 * Partial or complete neutralization of the polyanionic additive can be used for low pH control in the hollander, if desired.

30 Blame them

As a rule, additives for a Dutchman must be diluted before they are added to the Hollander. The fiber slurry or "load" in the hollander usually contains about 0.5-0.3 wt.% Solid fiber material in water. Additives preferably also serve up to 0.5-20 Jf, more preferably up to 0. 5-10, or even better to 0.5-5, total solids to be diluted 7810366 10 before being added in the hollander The polycationic additive is generally prepared as a dry liquefying solid and must be Dissolved or dispersed in the concentration mentioned above in water. Binder latices as commercially available contain about 25-60% by weight or slightly more of total solids of the dry latex as a control gel and they can also be diluted, as indicated, The polyaniozene additive is prepared and sold as a dry solid or as an aqueous solution, containing 15-5% solids in total, if the latter contains the higher concentrations, it should be esterified 10 thin, as stated for the best possible addition.

In the practice of the method of the invention, the fibers are added to water in the hollander and grinding is started.

Once a suitable slurry-like consistency has been achieved and as grinding or stirring is continued, the solution or dispersion of the polycationic additive is added and the mixture is left for at least a short time, usually about 30 seconds to 1 or 2 minutes or more, ground or stirred, before the additive is carefully and homogeneously mixed with the entire volume of the load in the hollander. While the appearance of the charge does not change significantly during or after the addition of the polycationic additive, it has been concluded that the incorporation of the polycationic additive by the fibers is generally very rapid. If this is not true, it should be noted that coagulate had formed in the serum phase after binder and polyanionic material were added, but this has never been the case.

As already mentioned, the binder latex can be added soon after the addition of the polycationic additive. When the binder is added, the charge in the hollander becomes milky and little deposition on the fibers is observed. Again, grinding or stirring must be continued for a short time to allow the latex to distribute homogeneously throughout the amount of the charge.

At this point of the stepwise order of addition, a curing agent, if desired or necessary for the binder or other additive, should be added before the polyanionic additive is added. Such curing agents and additives should be prepared as an aqueous solution, an aqueous dispersion or as a mixed solution / dispersion in water so that they are homogeneously dispersed in the serum phase of the batch and in the next step. in which polyanionic additive is added can be precipitated or coagulated together with the binder latex. Again, the batch should be ground or stirred in the hollander until a good distribution of the curing agent and additives is achieved.

When adding the polyanionic additive, there is as a rule no sudden change in the appearance of the charge. However, as stirring or grinding is continued, a gradual decrease in milkiness is observed (especially in laboratory tests, which are done in glass). As a rule, the milkiness disappears almost completely in two to five minutes, indicating coagulation of the binder and deposition on the fibers. This is confirmed by making a sheet, taking a sample of the "white water" drawn from the wet fiber mat and analyzing it for total solids content. Although the batch can still be ground after the coagulation and is not disadvantageous, once the milky milk has disappeared, the batch is ready for sheet formation and can be transferred to the wet screen section of the paper machine.

Several tests have been carried out, which are further explained in the examples given below, comparing the meals with the dry tensile strength of the final fiber fabric and with and without the three essential additives of the invention. With bleached "Southern" kraft pulp and without additives, but with the known method, before or after adding a solution of papermakers alum 25 with a total solid content of 10%, the binder latex was added, it was found that the dry tensile strength moderate and continues to rise with a total meal of 600 seconds in a Waring type laboratory mixer. At the same conditions and with the same pulp, but using the system of three essential additives of the invention, the dry tensile strength of the sheet after 30-100 seconds is as high or higher than was achieved at 300-600 seconds without additives and no binder or without additives, but with a known alum-coagulated binder.

As in known processes, any desired amount of total solids of the polymeric binder may be added in the process of the invention up to about 50% dry matter by weight of the total dry fiber weight. The addition of 20-1 * 0 wt.% Solid binders is very common. It will be clear here that both the polycationic and the polyanionic additives are polymeric in nature and have at least a certain binding effect. It is extremely rigorous to add the weight of the polymeric additives to the weight of the binder. In view of what is usual in practice because in each case the amount of additives is small, the weight of required binder is stated separately. In the process of the invention, as a rule, between about HO and 50 weight percent solid binder materials are added without other polymeric additives.

The amount of the polycationic and of the polyanionic additives added into the holander can vary widely, but very good results are obtained with about 0.05-7 wt. 5% dry matter relative to the total dry weight fiber. More preferably, and often also with better results, between about 0.1 and 5 parts by weight of each additive can be used on the same basis. As a rule, good results are obtained with between about 0.1 and 1% by weight of each additive, counted as dry material. As a rule, the total weight of additives is very small relative to the total weight of fibers or relative to the amount of binder polymer used.

The weight ratio of polycationic additive to polyanionic additive can vary widely between 15: 1 and 1: 5, but better results are achieved with narrower ratios between 10: 1 and 1: 2. The slightest white water losses appear to be achieved at even narrower ratios of about 3: 1 to about 1: 1.

The invention will now be further illustrated by the examples below, which are intended to be illustrative only.

In the examples below, a standard laboratory sheet-making technique was used, using a Waring type laboratory mixer instead of a conventional papermaker mill to better observe the fiber slurry during its preparation. In the method, first the Canadian Standard Freeness was determined and then the slurry was processed into a sheet in a Williams Standard Pulp Testing Appara-35.

7810366 \ 13

The procedure was as follows: 1. Add 35 grams of fiber and 1500 ml cold {25 ° C) tap water in a Waring mixer of approximately 5 liters. These quantities gave a slurry of M.

5 2. Mix at low speed for 30 seconds.

3. Pour the slurry into an open beaker of k liters and dilute with cold tap water to 3 * 75 liters.

k. Add approximately 50 ml of a 5J polycationic solution to the slurry in the beaker and stir again at 250 rpm for 1 minute. Here also add any curing agent and stir again. Determine the pH.

5. Add 10.5 grams (dry weight) of a binder latex and stir for 1 minute. 30 wt.% Solid binder materials are added with this amount. Determine the pH.

6. Add KO ml of a 55 * solution of the polyanionic additive.

7. Continue stirring until the serum vessel is clear. The deposition of the binder on the fibers is usually complete in 1-5 minutes.

decorated. Determine the pH.

8. Add 10 ml of the fiber slurry in a calibrated measuring cylinder of 20 1 liter and dilute with cold tap water to 1 liter. Invert the measuring cylinder three times to properly disperse the fibers and pour the dispersed contents of the measuring cylinder into a Canadian Standard Freeness (CSF) device. Measure the volume of flooded water in milliliters and record its value. The volume thus found in ml is the CSF value.

25 9. Add 10 liters of cold tap water into the Williams Standard Pulp

Testing Apparatus and then add the rest of the fiber slurry to this device.

Stir to disperse the fibers. Open the drain valve and simultaneously turn on a timer. Stop this device when the surface water disappears from the formed sheet. The time 30 thus found in seconds is dewatering time.

10. Remove the fiber sheet from the device and cut out a piece of 25 x 25 cm. Place this piece between unbleached cotton twill cloth.

Press the assembly for 30 seconds in a press at approximately 280,000 kPa.

11. Dry the pressed-out sheet in an air oven at about 135 ° C for 20 minutes. Determine the thickness and density of the dried sheet.

7810366 t 1¾.

12. Cut 2.5 x 15 cm strips from the dried sheets and determine the dry tensile strength of three such strips with an Instron device at 2.0 kg and a crosshead speed of 30 cm / min. For three such strips, the dry tensile strength and mean values are calculated, so that the mean, which counts as the dry tensile strength of the sheet, is found.

Example I

In this example, three comparisons were made between (1) sheets of paper made without additives and without binder, (2) sheets of paper made with a binder latex of a butadiene-acrylonitrile copolymer, which is approximately 65 weight percent combined butadiene and 35 weight percent Acrylonitrile contained and was made with mixed fatty acid and synthetic anionic emulsifiers, such as with known coagulation with alum as with the anionic coagulation system of this invention and (3) sheets of paper made using a self-curing ( heat-reactive acrylic binder latex, which is commercially available under the trademark "Hycar 2600 x 210" and consists of a copolymer of n-butyl acrylate and an acrylamide co-monomer manufactured by The BF Goodrich Company, Chemical Division, Cleveland,

Ohio is marketed and coagulated by the ionic coagulite system of the invention. The fiber consisted in all cases of Southern bleached kraft pulp. The polycationic additive was in all cases a trimethylamine (TMA) quaternary ammonium salt of a copolymer containing about 68 parts by weight epichlorohydrin and 32 parts by weight ethylene oxide.

The average molecular weight of the epichlorohydrin copolymer was 10,000-20,000. The polyanionic additive was an aqueous solution of polyacrylic acid with an average molecular weight of 100,000-220,000; a solution thereof with a total of 15 µl solid has a pH of 2-3 and a viscosity of 8000 cos (Brookfield RVT at 20 rpm).

The pulp-only slurry had a pH 7.3-7.5. After the addition of a 105 alum solution, the slurry had a pH of 3.3. When 1 + 0 was added, 30% by weight of the described butadiene-acrylonitrile binder latex (pH 9 * 5), the pH of the suspension rose to only bt5. Thus, with the known alum / binder system, the slurry clearly remained on the acidic side of neutrality, even when a high concentration of a strongly alkaline binder latex was used.

However, upon addition of the polycationic additive of the invention 7810366, the pH of the slurry dropped from about 7.3 to 7 * 0. When an alkaline binder latex (pH 9.5) was added, the slurry's pH returned to 7.6. Finally, upon addition of the highly acidic solution of the polyanionic polyacrylic acid, the final pH of the slurry was lowered to 5.2. However, when the slightly acidic reactive acrylic hindrance latex described above (pH M) was added to the slurry, which already contained the polycationic additives, the slurry pH only dropped from 7.3 to 7.2.

After addition of the polyacrylic acid, the final slurry had a pH kf2 and this week in veins did not differ from that of the alum coagulated slurry. The table below lists the meals, defroster times, CSF values, field thickness, density and dry tensile strength of all sheets of the above three comparative tests.

7810368 16

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These data show that when milling without binder is sufficient to obtain a sheet of paper with good dry tensile strength, the dewatering times have increased considerably, indicating that dewatering is likely in the sieve portion of a particular paper machine less complete, which means a greater load on the dryer rollers. With an alum-coagulated binder, this chance is less likely, but the meal is still great. When the ionic coagulation system of the invention is used, the meal is reduced by 10% or less with the same binder relative to the known alum coagulation. What is particularly important from No. 10 shows where an improved or more modern binder is used; it appears that a sheet of paper with a very high dry tensile strength is obtained with very short total meals and with a short dewatering time. These data show that the method of the invention consumes little energy compared to known methods.

Example II

In this example, another efficient reactive acrylic binder of the type used in the previous example was used at different charges to demonstrate that by the process of the invention and using the same polycationic and the same poly- anionic additives as in the previous example, although in other molar amounts, less binder can be used. 17th known method as described was used, only the amounts of the 25 components were varied in the manner mentioned below. Unbleached Southern kraft pulp was used in these experiments.

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From the data of Table B "it appears that a dry tensile strength of about 1,000 kPa was obtained with an amount of binder of only 20 parts by weight dry latex solids compared to the dry weight of fibers, that is, a saving of 50 by weight binder relative to the butadiene / acrylonitrile binder as used in the previous example The same data shows that a very high dry tensile strength of about 21000-60000 kPa was obtained in sheets containing the more usual amounts of Contains 30 binder and this was the case with a lower quality pulp than was used in the previous Example 10. The data also shows that with an effective adjustment of the weight ratios between polycationic additive and polyanionic additive white water losses to very low values can be reduced, because smaller losses are favored by the lower ratios.

Example III

In this example, the polycationic quaternary salts of various homopolymers and copolymers of epichlorohydrin were examined; these were prepared with trimethylamine (TMA) or piperidine as a quaternizing agent. Also, a quaternary salt of dimethylaminoethyl methacrylate reacted with ethyl chloride was used for comparison. The pulp used in all cases was the same as used in Example II; its amount was 5.71 JÉ at a 1: 1 weight ratio between polycationic additive and polyanionic additive. The binder used was the reactive acrylic binder "Hycar 2600 x 210" used in Example I.

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From these data it is very clear that the cationic additive must be polymeric and not monameric in nature. The data also shows that there is no clear difference between either of the tertiary monoamines used as the ternating agent or between the homopolymer and copolymer forms of epichlorohydrin polymers.

Furthermore, the quaternary salt of the copolymer of dimethylaminoethyl methacrylate and stearyl methacrylate is a polycationic additive which compares favorably with the quaternized epichlorohydrin polymers in efficiency.

Example IV

In this example, a number of experimental polycationic additives of the invention were examined at 0.57% by weight and the sheets were compared to those made with various commercially available polycationic paper additives according to the manufacturer's directions were added to the pulp slurry. Where a binder was used, it was the same reactive acrylic binder used in Example I and in all cases the latter was added in an amount of 30%. Where used, 5.7% by weight of the polyanionic additive of the previous examples was used in all cases. In . In all cases, the grinding time was 30 seconds.

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The data shows that a polycationic additive used without a binder or a polyanionic additive gives very poor results and high white water losses. It has also been found that of the aminoacrylate polymers, the homopolymer is the best and that no more than 50 µt of the aminoacrylate monomer can be replaced by a non-amino monomer. All polycationic additives 1 through 5 yielded small losses of vitvater.

Example V

In this example, the method of the invention was used to make paper from a ceramic fiber under the name "Fiberfax" by Carborumdum Ine. is placed on the market. Approximately 70 grams of the fiber was ground in water in a Waring blender according to the standard method described. The product was a thick loose sheet of 2.5 microns thick, well formed and of the type vas used in automobile converters.

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Claims (6)

1. A method of manufacturing paper using the "wet-laid" method from fibers of a neutral or anionic nature, wherein a latex of polymer binder is added in the hollander, characterized in that the fiber in the hollander is at least three polymeric additives are added in the following order: (1) an aqueous solution or dispersion of a polycationic hydrophilic, water-soluble or dispersible polymer quaternary salt, which polymer-bonded quaternizing groups, belonging to halide and monoamino groups; (2) a binder latex and (3) an aqueous solution of a polyanionic hydrophilic, water-soluble polymer, belonging to the carboxylic, and alkali, ammonium and amine salt forms of a polymerized acrylic acid, after which the resulting binder, batch 15 is converted into a sheet and the sheet is dried to obtain paper. 2. Process according to claim 1, characterized in that the additive of step (1) is a quaternary salt formed by reaction of a polymer containing 50-500 wt.% Of a combined epihalohydrin and 20 wt.% of a combined alkylene oxide containing from 2 to 8 carbon atoms per molecule, with from 1 to 25 moles of a tertiary monoamine per mole, polymer-bound halogen may be present in the polymer. 3. Process according to claim 1, characterized in that the additive of step (1) is also a quaternary salt formed by reaction of an organohalide quaternizing agent and a polymer of a monoaminoalkanol ester of an acrylic acid and the latter mentioned polymer no more than 50 weight percent of the ester is replaced with a non-amino monovinylidene monomer. 4. Process according to claim 1, characterized in that the additive of step (1) is also a quaternized salt, formed by reaction of a polymer, which combines about 60-100 wt.% Epichlorohydrin and at most about wt. combined ethylene oxide, with 1-25 moles of a tertiary monoamine per mole of combined chlorine in the polymer, the additive of step (2) being about 10-50 wt.% (as dry matter) relative to the dry weight of the fiber in the charge and the 7810366 2 6 / additive in step (3) is polyacrylic acid with an average molecular weight of 10000-20000, the additives in steps (1) and (3) each in an amount of 0.05-7 % by weight (calculated as dry matter) relative to the dry weight of fiber in the batch are added. Paper produced using the method according to any one of the preceding claims. r% 78 1 0 3 6 S 'I "V -Si ¥ Improvement of errata in the description associated with patent application No. 78.10366 Ned proposed by applicant dated November 1, 1978_________ Page 20, Table C: penultimate line: that is, <" delete. IJff / lH Λ /! 1 '«Ij J ·' 1I1 ü" 7810366