MXPA01003657A - Improved paper sizing agents and methods of making the agents and sizing paper - Google Patents

Abstract

Sizing agents comprised of dispersed synthetic polymers in an aqueous solution are provided, as well as methods for making these sizing agents and methods for using these sizing agents to size paper. The polymers are prepared by copolymerizing styrene which optionally may be substituted and certain acrylates in the presence of a stabilizing agent. Improved sizing is obtained by including recurring units of methyl acrylate, ethyl acrylate, and/or propyl acrylate in the synthetic polymers.

Description

PAPER APPRESSANT AGENTS AND IMPROVED METHODS FIELD OF THE INVENTION This invention relates to improvements in the sizing of products based on cellulose, for example paper. More specifically, it relates to a method for preparing a sizing agent, consisting in copolymecting a mixture of ethylenically unsaturated monomers in the presence of water to form a sizing dispersion, with agents aprestantes that can be obtained by this method and with sizing methods of products based on cellulose using these aprestantes agents. BACKGROUND OF THE INVENTION Synthetic polymers are widely used as agents available for products based on cellulose, for example paper, cardboard, etc. When added or applied during the papermaking process or at the end of the paper, the prepping agents generally improve paper properties such as printability, imparting a The hydrophobic character to the surface of the paper and thereby avoiding or reducing the flow of ink to, or through, the surface of the paper. Polymers that impart these characteristics to paper generally have a nature hydrophobic and, therefore, can be soluble or insoluble in aqueous solution, depending on the level of hydrophobicity incorporated. When they are soluble in water, they can be supplied to the user in the form of an aqueous solution. When they are insoluble in water, they can be conveniently supplied to the user in the form of aqueous dispersions or emulsions, wherein small particles or droplets of the sizing polymer are dispersed through an aqueous solution. These aqueous dispersions or emulsions are formed, in In general, polymerizing or copolymerizing monomers in the presence of water. To facilitate the formation of a dispersion or emulsion and to prevent the forming polymer from coagulating immediately into a large mass, there is often the presence of emulsifiers and surfactants during the polymerization for help in the formation of the dispersion and / or stabilize the final product. For example, in WO 97/37078 it is said that anionic, cationic, amphoteric and nonionic emulsifiers can be used. However, in some cases the use of surfactants and / or emulsifiers may result in indentable foaming and a lower sizing when they are present during the papermaking process. Many conventional polymeric surfactants contain repeating units of an ethyleneically comonomer.

The unsaturated compound containing carboxylic acid or sulfonic acid groups or salts thereof, see, for example, WO 97/37078 and U.S. Patent Nos. 5,240,771, 5,231,145, 5,139. 614, 5,138,004, 4,115,331, 4,030,970 and 4,001,193, all of which are incorporated herein by reference, however, since salt and acid forms often have different solubilities, the inclusion of these repetitive units in surface sizes can having the undesirable effect of increasing the pH sensitivity of the sizing agent, in some cases so much that the ability of the squeezing agent to function for its intended use is greatly altered.In recent years, other preventative agents have been developed, example styrene / acrylate emulsions, which do not include repeating units of an ethylenically unsaturated comonomer containing carboxylic acid or sulphonic acid groups or their salts, however, even for preparing agents in which the inclusion of these units is optional, see for example the USA. No. 4,835,212, there is still a problem, in the sense that it is desired to further improve its sizing capacity and / or dispersion stability. Therefore, there is a problem in that existing precursor agents often contain undesirable levels of surfactants, emulsifiers and / or acidic repeat units - see US. 5,258,466. The simple elimination of these components of the formulation has proved unsatisfactory, since the elimination frequently causes undesirable reductions in the squeezing capacity and / or the dispersion stability. Therefore, the problem of reducing the levels of surfactants, emulsifiers and / or acidic components in the precursor agents is complicated by the need to retain or improve the squeezing capacity and stability of the dispersion. Surprisingly, it has now been discovered that prepping agents can be prepared by polymerizing the monomeric components of a monomer mixture, where the mixture contains effective amounts of methyl acrylate, ethyl acrylate or propyl acrylate, and a stabilizing agent in the presence of water. and in the absence of both (a) ethylenically unsaturated carboxylic and sulfonic acids and their salts and (b) emulsifier or surfactant with a molecular weight of less than about 1,000, to obtain dispersions having the ability to impart a degree of sizing to the cellulose-based products as good as that of comparable products containing acidic and / or emulsifier or surfactant repeating units and / or lacking effective amounts of methyl acrylate, ethyl acrylate or propyl acrylate. Surprisingly, the present dispersions of the present invention also exhibit the improved physical characteristic frequently associated with the ethylenically unsaturated carboxylic and sulfonic acids and their salts and / or the emulsifier or surfactant without the use of these components. SUMMARY OF THE INVENTION The present invention relates to a method for preparing a sizing agent, comprising: (I) forming a mixture composed of (A) 5-40% by weight, based on the total weight, of ethylenically unsaturated monomers , composed of (1) 20-80 mole%, based on the total moles of monomers, of at least one monomer selected from the group consisting of styrene, styrene substituted with C? -C alkyl, alpha-methylstyrene and halogenated tireno in the ring; (2) 0-80 mole%, based on the total moles of monomers, of at least one monomer of C 4 -C 2 alkyl (meth) acrylate; (3) 5-50 mole%, based on the total moles of monomers, of at least one monomer selected from the group consisting of methyl acrylate, ethyl acrylate and propyl acrylate, and (B) a stabilizing agent selected from the group consisting of polysaccharide and synthetic water-soluble polymer with a weight-average molecular weight of 1,000 or greater, wherein the ratio of said (A) to said (B) in said mixture is in the range of about 0.6 : 1 to about 1.7: 1 and wherein said mixture is substantially free of both (i) ethylenically unsaturated carboxylic and sulfonic acids and their salts and (ii) emulsifier or surfactant with a molecular weight of less than 1,000, and ( II) copolymerizing said ethylenically unsaturated monomers in the presence of water to form a dispersion. The present invention also relates to a sizing agent composed of: (A) 5-40% by weight, based on the total weight, of a synthetic polymer composed of (1) 20-80 mole%, based on the total moles of repeating units, of at least one repeating unit selected from the group consisting of styrene, styrene substituted with alkyl C C4, alpha-methylstyrene and halogenated styrene in the ring, (2) 0-80 mol%, based on the total moles of repeating units, of at least one repeating unit of C4 alkyl (meth) acrylate. -C? 2; (3) 5-50 mole%, based on the moles of repeating units, of at least one repeating unit selected from the group consisting of methyl acrylate, ethyl acrylate and propyl acrylate, and ( B) a stabilizing agent selected from the group consisting of polysaccharide and synthetic water-soluble polymer with a weight-average molecular weight of 1,000 or greater, wherein the weight ratio of said (A) to said (B) in said sizing agent is in the range from about 0.6: 1 to about 1.7: 1, where I gave The sizing agent is substantially free of emulsifier or surfactant with a molecular weight of less than 1,000 and wherein said synthetic polymer is substantially free of repetitive acid units. The present invention also relates to a method for preparing paper, consisting of: (a) having a stock of paper, (b) disposing of the squeezing agent described above, (c) forming a web with said stock of paper and (d) ) mixing said sizing agent with said paper stock or applying said sizing agent to said web, in an amount effective to squeeze the paper formed from said web. DETAILED DESCRIPTION The precursor agents of this invention are generally dispersions of water insoluble polymers in aqueous solutions. The dispersed polymer particles or droplets can be obtained by polymerization of the corresponding monomers in the presence of water. The polymerization is generally carried out by forming a mixture consisting of water and about 5% to about 40%, preferably about 8% to about 30%, more preferably about 10% to about 5 to 25%, by weight, based on the total weight of the dispersion, of ethylenically unsaturated monomers and subjecting the mixture to polymerization conditions, preferably with stirring and, preferably, in the presence of a stabilizing agent. The resulting dispersion or squeezing agent, such As those terms are used herein, it is an aqueous dispersion composed of dispersed hydroinsoluble polymer particles finely divided in aqueous solution, which preferably contain a stabilizing agent. The ethylenically unsaturated monomers are generally constituted by two or three types of monomers, listed here as (1), (2) and (3). Thus, ethylenically unsaturated monomers are generally constituted by (1) about 20% to about 80%, preferably about 30% to about 75%, more preferably about 40% to about 60%, molar based on the total moles of monomers, of at least one monomer selected from the group consisting of styrene, alpha-methylstyrene, styrene substituted with alkyl A ^? ki ^^ lo C? -C / for example vinyltoluene, and halogenated styrene in the ring, for example chlorostyrene. Stretch is preferred. The ethylenically unsaturated monomers can also be composed of (2) about zero (0%) to about 80%, preferably 10% to about 60%, more preferably about 20% to about 50%, molar based to the total moles of monomers, of at least one monomer of C -C 2 alkyl (meth) acrylate. Suitable monomers include: n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, neopentyl (meth) acrylate, hexyl (meth) acrylate, (met) cyclohexyl acrylate, 2-ethylhexyl (meth) acrylate, heptyl (meth) acrylate, octyl, (meth) acrylate, decyl (meth) acrylate, palmityl (meth) acrylate and (meth) acrylate of stearyl. Butyl acrylate is preferred. The ethylenically unsaturated monomers also generally contain (3) from about 5% to about 50%, preferably from about 8% to about 30%, more preferably from about 10% to about 20%, molar in based on the total moles of monomers, of at least one selected monomer The group consisting of methyl acrylate, ethyl acrylate and propyl acrylate is preferred, methyl acrylate and ethyl acrylate are particularly preferred. methyl, ethyl acrylate and / or pro-pyl acrylate generally allows the formation of suitable agents which provide satisfactory or improved sizing effects without the need for ethylenically unsaturated carboxylic and sulphonic acids and their salts or emulsifier or surfactant with a molecular weight of less than about 1000. In addition to the ethylenically unsaturated monomers of (1), (2) and (3), other ethylenically unsaturated monomers may also be included, as examples of other suitable monomers which may be copolymerized with the monomers of (1), (2) and (3) include (meth) acrylamide, alkyl (meth) acrylamide and hydroxy functional monomers, for example hydroxyethyl methacrylate and hydroxyethyl acrylate. the acril-amide. The amounts of these other ethylenically unsaturated monomers are generally about 20% or less, preferably 10% or less, molar based on the total moles of monomers. In terms of amounts, the molar percentages of the ethylenically unsaturated monomers (1), (2), (3) and other monomers always add up to 100.

The polymerization of the ethylenically unsaturated monomers is generally carried out by stirring the monomers in water in any way and subjecting the monomers to polymerization conditions. The polymerization can be initiated, preferably in the absence of oxygen and in the presence of an inert gas, for example nitrogen, by adding a suitable polymerization initiator. Initiators include conventional initiators, such as ammonium persulfate, hydrogen peroxide, hydroperoxide, benzoyl peroxide, organic peroxides and azo-type initiators, for example 2, 2'-azobisisobutyronitrile (AIBN), as well as redox systems, such as sulfur dioxide / hydrogen peroxide, sulfur dioxide / t-butyl hydroperoxide, sulfur dioxide / sodium bromate, iron (II) / hydrogen peroxide, iron (II) / sodium persulfate, iron ( II) / potassium persulfate, iron (II) / ammonium persulfate, ammonium persulphate / sodium metabisulfite, sodium persulphate / sodium metabisulfite, potassium persulfate / sodium metabisulfite and peroxy redox initiators. Iron (II) / hydrogen peroxide is preferred. Ultraviolet radiation can be used to initiate polymerization. The polymerization temperatures are generally in the range of about 20 ° C to about 100 ° C, depending on the type of initiator, • > -i? 6í i & * »jÍ & a. .-? & e, ^^^ ... ^. ^ ¿-aaaa although occasionally higher or lower temperatures may be suitable. For example, the polymerization temperature can be adjusted to avoid undesirable volatilization of monomers during polymerization. Preferably, a conventional initiator, more preferably hydrogen peroxide, is added at the end or near the end of the polymerization to reduce the residual monomer content of the resulting aqueous dispersion. The polymerization process can be carried out in batch form or by feeding the monomers continuously or in stages, or in any combination thereof. Water can also be added at any time during the polymerization process, as well as additional aliquots of initiator or other polymerization aids. Preferably, the polymerization of the ethylenically unsaturated monomers is conducted in the presence of a stabilizing agent, which stabilizes the final product. For example, a mixture composed of the monomers, a suitable stabilizing agent and water can be prepared and the monomers then polymerized as described herein to form a sizing dispersion. The amount of stabilizing agent is preferably from about 8% to about 30%, more preferably from about 10% to about 20%, by weight based on the total weight of the dispersion. The weight ratio of ethylenically unsaturated monomers to stabilizing agent in the mixture is generally in the range of from about 0.6: 1 to about 1.7: 1, preferably from about 0.8: 1 to about 1.5: 1, more preferably from about 0.9: 1 to about 1.2: 1. Since the complete conversion of monomers into polymers is generally achieved by the practice of the present invention, the weight ratio of ethylenically unsaturated monomers to stabilizing agent in the mixture is generally equivalent to the weight ratio of polymer formed to stabilizing agent. in the resulting squeezing dispersion. A suitable stabilizing agent is a polysaccharide. The polysaccharide can be a water-soluble alginate (sodium or potassium), carboxymethylcellulose, hydroxyethylcellulose or a starch, preferably a starch. Suitable starches include: barley, wheat, potato, corn, waxy corn, rice, tapioca, sorghum or wheat, preferably waxy corn. The starch can be converted, for example, with enzymes, acids, thermochemically and by oxidation, preferably by oxidation. The starch can also be modified, for example, with acid and pregelatinization. The starch can also be chemically treated, for example by etherification, esterification, crosslinking and ionic treatment, for example cationic, anionic and amphoteric, preferably cationic. Starches that have been treated by a combination of the aforementioned treatments, as well as the mixtures of the aforementioned starches, can also be used. A preferred starch is cationic, more preferably oxidized cationic waxy corn starch. Another suitable, although less preferred, stabilizing agent is a water-soluble synthetic polymer having a weight-average molecular weight of about 1,000 or greater, preferably about 5,000 or greater, even more preferably greater than about 15,000, more preferably about 20,000 or greater. Molecular weights are weight means, measured by conventional high pressure size exclusion chromatography techniques, using suitable molecular weight standards, for example, pullulan polysaccharide standards. Suitable water-soluble synthetic polymers include polymers such as polyvinyl alcohol and polyacrylamide. Preferably, said water-soluble synthetic polymers are not acid-containing copolymers; for example, they are preferably substantially free of repeating units of monomers containing acid.

The ethylenically unsaturated monomers are generally polymerized, preferably in the presence of a stabilizing agent, in the presence of about 30% to about 85% water, preferably about 55% to about 80% by weight based on the total weight , to form a squeezing dispersion. The monomer mixture is substantially free of acrylic acid, methacrylic acid and other ethylenically unsaturated carboxylic acids, sulfonic acids and their salts. Surprisingly, it has been found that a better sizing can be obtained even when these acidic monomers are not included in the polymerization system. In addition, the mixture is, in general, substantially free of emulsifier or surfactant. In this context, the emulsifiers or surfactants are generally non-polymeric, preferably with a molecular weight of less than about 1,000, more preferably less than about 800. The distressing dispersions prepared as described herein are therefore constituted by a water-insoluble polymer that is dispersed in an aqueous solution, which preferably contains a stabilizing agent. Although, in theory, the water-insoluble polymer could be prepared by some other method and then dispersed in water to obtain jttMím? a + í Qftftft ÉÉEááál f! It is much more preferred to prepare these precursor agents by polymerization of the corresponding monomers as described herein. Therefore, the appressing dispersions of the present invention generally contain the amounts of the various components that are described herein as being present during the polymerization process or, in the case of the monomers, the resulting polymers thereof. For example, since the total conversion of the monomers into polymer is generally obtained by the practice of the present invention, the water-insoluble polymer generally contains repeating units in the same amounts as those described herein for the corresponding monomers in the polymerization mixture. The types and amounts of repeating units in the water-insoluble polymer are, therefore, described herein in terms of the corresponding monomers; for example, the water-insoluble polymer generally contains repeating units of monomers (1), (2) and (3) and, optionally, other repeating units, as described herein. Similarly, the water-insoluble polymer is preferably substantially free of acidic repeat units as described above, since the monomer mixture itself from which the polymer is preferably formed is preferably free of carboxylic acids and ethylenically unsaturated sulfonic acids and their you go out. The present prepping agents are generally free of emulsifier or surfactant with a molecular weight of less than 1,000, preferably they contain a stabilizing agent as described above and the weight ratio of water insoluble polymer to stabilizing agent in the sizing agent is generally in the same range as that specified above, for example in the range of from about 0.6: 1 to about 1.7: 1, preferably from about 0.8: 1 to about 1.5: 1, more preferably from about 0.9: 1 to about 1.2: 1. Likewise, the amount of water in the aqueous dispersions is generally from about 30% to about 85%, preferably from about 55% to about 80%, by weight based on the total weight, as described here. The present dispersions of the present invention generally exhibit good physical stability. Although there may be cases in which good physical stability is not required, for example when the size dispersion is used shortly after its preparation, in most cases a good physical stability is preferred. A dispersion of sizing is stable, for the purposes of this ^ invention, when the dispersed particles or droplets of polymer do not sediment and / or coagulate before use. Preferably, the dispersed polymer particles or droplets do not sediment and / or coagulate before 1 week has elapsed since the preparation of the dispersion, more preferably about 1 month, more preferably about 3 months. The precursor agents of this invention are generally used to prepare cellulose-based products. For example, the appressing agents of this invention can be mixed with a paper stock, the paper stock can be shaped into a web and the paper can be formed from the web. In addition, the preparing agents of this invention can be applied to the framework formed with the paper stock and paper can be formed with the finished fabric. In general, the amount of sizing agent is effective for sizing the paper formed from the lattice. Suitable amounts of sizing agent vary between about 0.05% and 5%, preferably between 0.1% and 0.4%, by weight of dry polymer based on the total weight of cellulose-based dry product. The conventional means known in the art can be used to apply the sizing agent to the cellulose based product. For example, the sizing agent may be sprayed onto the lattice, or a sizing press may be used to apply the sizing agent to the paper, or it may be applied as part of the conversion process using conventional coating techniques. The precursor agents of this invention can be used in conjunction with other additives conventionally used in the production of cellulose-based products or serially therewith. When practiced according to the present invention, the paper formed from a lattice to which the present prepping agents have been applied has a degree of sizing greater than when a sizing agent is used that does not contain repetitive units selected from the group consisting of acrylate. of methyl, ethyl acrylate and propyl acrylate in place of the sizing agent of the invention. A better sizing can be manifested by observing, for example, a lower ink shift, a sharper image of the letter, a better optical density and / or contrast, less color shift and / or better adhesion of the toner, - We penetrate the ink, shorter drying time, etc. Other advantages of the present agents of this invention include less foaming in their use, being usable over a wider range of pH, and a greater pear- transition of the vitreous state, which often results in reduced tackiness. The polymerization process of ethylenically unsaturated monomers also tends to proceed more rapidly and the process product can generally be prepared at a higher level of polymer solids and with a smaller particle size and narrower particle size distribution, providing a product less expensive and more uniform. The process also often gives a product that has less residual monomer and less clot. In many cases, one or more improved properties can be obtained simultaneously in a given product, but in other cases it may be desirable, for economic or other reasons, to obtain a product that has better properties in one area and equivalent or even diminished properties in another. area. For example, very high sizing levels may be desirable in making cardboard, even when the sizing level begins to affect in a detrimental way a property that is normally associated with a good sizing, such as printability. Thus, those skilled in the art realize that, in the context of actual production, it is often necessary or desirable to balance the benefits of various refinements against their costs, depending on the particular circumstances. The invention is further illustrated in the following examples, which are not to be taken as limiting the scope of the invention. All parts and percentages are by weight 5 based on total weight, unless otherwise indicated. General Gelatin Sizing Process A typical commercial oxidized starch is boiled for 20% by weight sizing press operations for 20 minutes, diluted to 3% by weight and then a NaOH solution is added to obtain a starch solution with a pH of 7.1-7.8. Various amounts of sizing agent are added to samples of this starch solution to produce staking solutions having slightly less than 3% by weight of starch. Cut heavy sheets of prepared paper Inside, which has a weight of about 70 grams / meter2, at a suitable size, they are immersed in the various appendant solutions, pressed at a pressure of 1.5 lbs, and then dried at 240 ° F for 30 seconds. The sheets are weighed after drying, and then the sizing levels are given in units of Ib / ton, that is, pounds of dry polymer per ton of dry paper. Testing the effectiveness of the dressing The effectiveness of the agents that were prepared was determined of different form carrying out tests of Penetration of the Ink, Quality of Impression, Density of Color, Densidad Óptica, Time of Drying and Adhesion of Toner on the prepared paper. The Foam Test was also used to measure the effectiveness of the dressing agents in terms of the tendency of the agents to foam during its application. The general procedures for these tests are provided below. Ink Penetration The ink penetration test method is similar to the TAPPI Method T 530 pm-89, except for the use of an instrument as described in the USA. 5,483,078. The test measures the time (in seconds) for the reflectance of the paper on the face opposite the one that contacts the ink to decrease to 80% of the initial value. The ink is a 1.95% Naftol Green B dye solution buffered at pH 7. The test values are normalized to the basis weight of the paper assuming the values vary as the base weight cube. The results are expressed below in units of seconds. Longer times are generally indicative of a better sizing. Quality of printing Print quality (CI) tests were carried out by first printing six 9-point Courier letters (e, o, j, m, v and d) on the paper using a commercial inkjet printer. The areas of the six letters were then measured using a commercial image analysis system 5 equipped with morphometric application, stereomicroscope with variable focus with CCD camera and ring fiber optic illumination. The images of the six characters were added to obtain a total area of letters. A smaller area of letters is usually indicative of a better sizing, since corresponding to less extension or wicking effect of the inked area. The results are expressed below in units of mm2. Color density The color density (DC) was determined by measuring the areas of composite black characters printed on a yellow background. The measurement procedure was similar to the one used to measure the areas of the letters in the print quality test, except for the fact that the yellow letters were printed on a black background using a color ink jet printer. . The results are expressed below in units of inverse mm2. A higher color density value is generally indicative of a better sizing.

Optical density Solid black areas of 1 cm2 were printed on the sheet to be studied. The optical density (OD) of the printed areas was measured with a commercial Macbeth machine room densitometer. The values given below are the average of four measurements in each of two areas and are given in units of inverse mm2. A higher value of optical density is generally indicative of a better fit. Toner adhesion test The toner adhesion test measures the adhesion of toner to cellulose-based products, for example paper. The test is performed by copying a standard toner adhesion test pattern consisting of nine small black blocks onto a sample sheet using a commercial photocopier. The samples are then folded and taped with a 5-pound roller and lightly brushed the crease to remove excess toner. The image analyzer used for the print quality test is then used to obtain a measurement of the total object area by measuring the amount of white produced by the fold that removes the image. Since this test measures the area in which the toner is removed, a lower value of total object area is generally more desirable. The results are given below in units of mm2. Drying time The drying time is a measurement of the time necessary for the ink to dry after being applied to a product based on cellulose, for example paper. The test is carried out by first printing a grid on the left side of a piece of paper and then printing a thick black line on the right side of the paper. The paper is then quickly folded and pressure is applied to the paper with a 5-pound roller. If the ink dries very quickly, the ink of the thick black line will not transfer to the grid. However, if the ink dries slowly, at least a portion of the thick black line will be transferred to the grid. The drying time is determined by measuring the length of the black line transferred on the grid and is then given in units of length (centimeters) . Foam test The results of the foam test are used as an indication of the amount of foaming that can be expected during papermaking. It is carried by adding 125 parts of sizing solution (prepared by intermixing primer and starch as described in the general gelatin sizing procedure given above) and 5 drops of a neutral blue ink to a commercial grade laboratory mixer, making operate the mixer at the highest speed for 10 seconds and then stop the mixer. The height of the foam is recorded immediately after stopping the mixing and the time is recorded for the foam to fall to a specified height. The results given below appear in units of minutes and seconds. A shorter time usually corresponds to a lower foaming. Measurements of particle size and distribution of particle size Microscopy: A commercially available electron microscope, equipped with automated image analysis, was used to examine specimens of appressing agents by coating a grid with carbon, placing a dilute drop of squeezing agent on the charcoal and then leaving the solution evaporated to deposit the polymer particles on the grid. The results are given below as the average diameter of the particles in units of nanometers (surface-volume method). Light scattering: A commercial particle analyzer by light scattering (Horiba) was used to determine the particle size of samples of appressing agents. The results are given below as the median particle size, in units of microns, and as the percentage of particles that have a diameter of less than one miera. Example A - Preparation of Stabilizing Agent A stabilizing agent was prepared as follows: Approximately 61.0 parts of water were added to a suitable vessel equipped with stirrer, followed by 0.8 parts of ammonium per-sulfate and 15.8 parts. parts of a commercial cationic waxy maize starch, for a total of 77.6 parts. The starch was oxidized by heating at 90 ° C for 130 minutes and then cooling. Example B - Preparation of Stabilizing Agent A stabilizing agent was prepared as follows: Approximately 134.3 parts of water was added to a suitable vessel equipped with a stirrer, followed by 2.7 parts of ammonium per-sulfate and 59.3 parts of water. a commercial cationic waxy corn starch. The starch was oxidized by heating at 90 ° C for 130 minutes and then cooling. Example C - Preparation of Stabilizing Agent A stabilizing agent was prepared as follows: Approximately 165.0 parts of water were added to a suitable vessel equipped with stirrer, followed by 2.2 parts of ammonium per-sulfate and 45.2 parts of a commercial cationic waxy corn starch, to obtain a total of approximately 212.5 parts. The starch was oxidized by heating at 90 ° C for 130 minutes and then cooling. Example 1 A sizing agent was prepared as follows: Approximately 0.1 part ferrous sulfate heptahydrate was added to about 76.4 parts of a stabilizing agent prepared as in Example A, followed by 7.4 parts of styrene, 8.8. parts of n-butyl acrylate and 1.4 parts of methyl acrylate. The reaction vessel was heated to about 57 ° C under a nitrogen atmosphere. Approximately 0.4 part of hydrogen peroxide and about 3.4 parts of water were added in the course of about 2.5 hours, while maintaining the temperature at 58 ° ± 2 ° C. About 0.03 parts of hydrogen peroxide and 0.27 parts of water were then added to reduce the residual monomer, followed by 0.3 parts of sodium hydroxide and 0.3 parts of water. The resulting sizing agent was an aqueous dispersion having a 17, 6% polymer solids formed and 15.7% stabilizing agent by weight, based on total weight (ratio 1.12: 1). Example 2C (Comparative) A comparative sizing agent was prepared without using methyl acrylate as follows: Approximately 0.1 part ferrous sulfate heptahydrate and 0.3 part water were added to about 76.4 parts of a stabilizing people prepared as described in Example A, followed by 8.1 parts of styrene and 9.5 parts of n-butyl acrylate. The reaction vessel was heated to about 57 ° C under a nitrogen atmosphere. Approximately 0.4 part of hydrogen peroxide and about 1.5 parts of water were added in the course of about 2.5 hours while maintaining the temperature at about 58 ° ± 2 ° C. About 0.03 parts of hydrogen peroxide and about 0.13 parts of water were then added to reduce the residual monomer, followed by about 0.3 part of sodium hydroxide and 0.8 part of water. The resulting comparative sizing agent was an aqueous dispersion having 17.6% polymer solids formed and 15.7% stabilizing agent by weight, based on the total weight (ratio 1, 12: 1). Example 3 The preparing agents prepared as in Examples 1 and 2C were used to prepare paper by the general gelatin sizing procedure described above. The effectiveness of sizing was determined by means of the print quality test (at 2 lb / ton and 4 lb / ton sizing levels) and by the ink penetration test (at a sizing level). 4 lb / ton), as described above. Next, the results are shown in Table 1 and these show that the sizing agent of the The present invention offered both better print quality and better ink penetration. Table 1 Example 4 A sizing agent was prepared as follows: Approximately 0.1 part ferrous sulfate heptahydrate was added to about 76.4 parts of a preparative stabilizing agent. as in Example A, followed by 8.1 parts of styrene, 6.9 parts of n-butyl acrylate and 2.6 parts of methyl acrylate. The reaction vessel was heated to about 58 ° C under a nitrogen atmosphere. Approximately 0.4 part of hydrogen peroxide and about 3.4 parts of water were added in the course of about 2.5 hours, while maintaining the temperature at 58 ° ± 2 ° C. Approximately 0.03 parts of hydrogen peroxide and 0.27 parts of water were then added to reduce the residual monomer, followed by 0.3 parts of sodium hydroxide and 0.8 parts of water. The resulting sizing agent was an aqueous dispersion having 17.6% polymer solids formed and 15.7% stabilizing agent by weight, based on the total weight (ratio 1.12: 1). Example 5 Stabilizing agents as in Examples 4 and 2C were used to prepare paper by the general gelatin sizing procedure described above, at a level of sizing agent of 4 lb / ton. The drying times were determined for the papers prepared by the drying time procedure described above. The results shown below in Table 2 show that the precuring agents of the present invention provide faster drying times than comparative tableting agents. Table 2 Example 6 A sizing agent was prepared as follows: Approximately 0.1 part of ferrous sulfate heptahydrate was added to about 76.4 parts of a stabilizing agent prepared as in Example A, followed by 8.7 parts of styrene, 7, 0 parts of n-butyl acrylate and 2.2 parts of methyl acrylate. The reaction vessel was heated to about 58 ° C under a nitrogen atmosphere. Approximately 0.4 part of hydrogen peroxide and about 3.4 parts of water were added over the course of about 2.5 hours while maintaining the temperature at about 60 ° ± 3 ° C. About 0.03 parts of hydrogen peroxide and 0.27 parts of water were then added to reduce the residual monomer, followed by 0.3 parts of sodium hydroxide and 0.8 parts of water. The resulting sizing agent was an aqueous dispersion having 17.6% polymer solids formed and 15.7% stabilizing agent by weight, based on the total weight (ratio 1.12: 1). Example 7 Preparative agents prepared as in Examples 6 and 2C were used to prepare paper by the general gelatin sizing procedure described above, at a level of sizing agent of 2 lb / ton. The effectiveness of sizing was determined by means of the toner adhesion test (at a sizing level of 2 lb / ton) and by means of the foam test (at a sizing level of 4 lb / ton), according to It has been described above. The results shown below in Table 3 show that the precuring agents of the present invention provide better toner adhesion and better foam time than the comparative finishing agents. Table 3 Example 8 A sizing agent was prepared as follows: Approximately 0 was added, 1 part ferrous sulfate heptahydrate to about 76.4 parts of a stabilizing agent prepared as in Example A, followed by 8.9 parts of styrene, 3.7 parts of n-butyl acrylate and 5.0 parts of acrylate of methyl. The reaction vessel was heated to about 58 ° C under a nitrogen atmosphere. Approximately 0.4 part of hydrogen peroxide and about 3.4 parts of water were added over about 2.5 hours, while maintaining the temperature at about 60 ° ± 3 ° C. About 0.03 parts of hydrogen peroxide and 0.27 parts of water were then added to reduce the residual monomer, followed by 0.3 parts of sodium hydroxide and 0.8 parts of water. The resulting sizing agent was an aqueous dispersion having 17.6% polymer solids formed and 15.7% stabilizing agent by weight, based on the total weight (ratio 1.12: 1). Example 9 Preparative agents prepared as in Examples 8 and 2C were used to prepare paper by the general gelatin sizing process described above. The effectiveness of sizing was determined by means of the print quality test (at 2 lb / ton and 4 lb / ton sizing levels) and through the ink penetration test (at ink sizing levels). 2 lb / ton and 4 lb / ton), as described above. The results are given below in Table 4 and show that the sizing agent of the present invention provides both better print quality and better ink penetration. Table 4 Example 10 A sizing agent without a monomer of (2) was prepared as follows: Approximately 0.1 part ferrous sulfate heptahydrate was added to about 76.4 parts of a stabilizing agent prepared as in Example A, followed by 9.6 Styrene parts and 7.9 parts of methyl acrylate. The reaction vessel was heated to about 58 ° C under a nitrogen atmosphere. Approximately 0.4 part of hydrogen peroxide and about 3.4 parts of water were added in the course of about 2.5 hours while maintaining the temperature at about 60 ° ± 3 ° C. About 0.03 parts of hydrogen peroxide and 0.27 parts of water were then added to reduce the residual monomer, followed by 0.3 parts of sodium hydroxide and 0.8 parts of water. The resulting sizing agent was an aqueous dispersion having 17.6% polymer solids formed and 15.7% stabilizing agent by weight, based on the total weight (ratio 1.12: 1). Example 11 Preparative agents prepared as in Examples 10 and 2C were used to prepare paper by the general gelatin sizing process described above. The effectiveness of sizing was determined by means of the ink penetration test (at sizing levels of 2 Ib / ton and 4 lb / ton), as described above. The results are given below in Table 5 and show that the sizing agent of the present invention provides better penetration of the ink.

Table 5 Example 12 A sizing agent was prepared as follows: Approximately 0.1 part of ferrous sulfate heptahydrate was added to about 76.4 parts of a stabilizing agent prepared as in Example A, followed by 8.1 parts of styrene, 8.6 butyl acrylate portions and 0.9 parts ethyl acrylate. The reaction vessel was heated to about 58 ° C under a nitrogen atmosphere. Approximately 0.4 part of hydrogen peroxide and about 3.4 parts of water were added in the course of about 2.5 hours while maintaining the temperature at about 60 ° ± 3 ° C. About 0.03 parts of hydrogen peroxide and 0.27 parts of water were then added to reduce the residual monomer, followed by 0.3 parts of sodium hydroxide and 0.8 parts of water. The resulting sizing agent was an aqueous dispersion having 17.6% polymer solids formed and 15.7% polymer solids formed and 15.7% stabilizing agent by weight, based on the total weight (ratio 1.12: 1). Example 13 Preparative agents prepared as in Examples 12 and 2C were used to prepare paper by the general gelatin-sizing process described above. The effectiveness of sizing was determined by means of the print quality test (at 2 lb / ton and 4 lb / ton sizing levels) and by the ink penetration test (at ink sizing levels). 2 lb / ton and 4 lb / ton), as described above. The results are given below in Table 6 and show that the sizing agent of the present invention provides both better print quality and better ink penetration. Table 6 Example 14 A sizing agent was prepared as follows: about 0.1 part ferrous sulfate heptahydrate to about 76.4 parts of a stabilizing agent prepared as in Example A, followed by 8.1 parts of styrene, 7. 3 parts of butyl acrylate and 2.1 parts of ethyl acrylate. The reaction vessel was heated to approximately 58 ° C under a nitrogen atmosphere. Approximately 0.4 part of hydrogen peroxide was added and approximately 3. 4 parts of water in the course of approximately 2.5 hours, while maintaining the temperature at approximately 60 ° ± 3 ° C. Then, approximately 0.03 parts of hydrogen peroxide were added and, 27 parts of water to reduce the residual monomer, followed by 0.3 parts of sodium hydroxide and 0.8 parts of water. The resulting sizing agent was an aqueous dispersion having 17.6% polymer solids formed and 15.7% stabilizing agent by weight, based on the total weight (Reason Example 15) Preparative agents prepared as in the Examples were used 14 and 2C for sizing paper by the general gelatin sizing procedure described above The sizing effectiveness was determined by the print quality test (at 2 lb / ton and 4 lb / s sizing levels). ton) and by means of the ink penetration test (at sizing levels of 2 lb / ton and 4 lb / ton), as described above. The results are given below in Table 7 and show that the sizing agent of the present invention provides both better print quality and better ink penetration.

Table 7 Example 16 A sizing agent was prepared as follows: Approximately 16.5 parts of water and 0.1 part of ferrous sulfate heptahydrate were added to about 52.9 parts of the stabilizing agent of Example B at about 68 ° C, followed by 18, 0 parts of styrene, 3.6 parts of n-butyl acrylate and 2.4 parts of methyl acrylate. The reaction vessel was maintained at about 68 ° C and placed under a nitrogen atmosphere. About 0.4 part of hydrogen peroxide and about 3.2 parts of water were added in the course of about 2.5 hours while maintaining the temperature at about 68 ° ± 3 ° C. About 0.03 parts of hydrogen peroxide and 0.3 parts of water were then added to reduce the residual monomer, followed by 0.4 parts of sodium hydroxide and 1.8 parts of water. The resulting sizing agent was an aqueous dispersion having 24% polymer solids formed and 16% stabilizing agent by weight, based on the total weight (1.5: 1 ratio). Example 17 A sizing agent was prepared as follows: Approximately 0.1 part ferrous sulfate heptahydrate was added to about 78.5 parts of the stabilizing agent of Example B at about 65 ° C, followed by 8.5 parts of styrene, 6, 9 parts of n-butyl acrylate and 2.1 parts of methyl acrylate. The reaction vessel was cooled to about 58 ° C and placed under a nitrogen atmosphere. Approximately 0.4 part of hydrogen peroxide and about 1.4 parts of water were added in the course of about 2.5 hours while maintaining the temperature at about 60 ° ± 3 ° C. Approximately 0.03 parts of hydrogen peroxide and 0.3 parts of water were then added to reduce the residual monomer. dual, followed by 0.3 parts of sodium hydroxide and 1.3 parts of water. The resulting sizing agent was an aqueous dispersion having 17.6% polymer solids formed and 15.7% stabilizing agent by weight, based on the total weight (ratio 1.12: 1). The following Examples 18-26 illustrate how the comonomer content, the total monomer content and the stabilizing agent content of the targeting agents can be varied within the scope of the present invention. Example 18 Preparative agents prepared as in Examples 16 and 17 were used to prepare paper by the general gelatin sizing process described above. The effectiveness of sizing was determined by means of the print quality test, by means of the ink penetration test, by means of the optical density test and by means of the color density test. , each at 2 lb / ton and 4 lb / ton sizing levels and carried out as described above. The results are given below in Tables 8 and 9 and show the effects of the variation of the comonomer content and the content of total monomers on the effectiveness of the sizing.

Table 8 Table 9 Example 19 A sizing agent was prepared as follows: Approximately 51.2 parts of water and 0.04 parts of ferrous sulfate heptahydrate were added to about 37.7 parts of the stabilizing agent of Example B at about 48 ° C, followed by 3, 5 parts of styrene, 3.1 parts of n-butyl acrylate and 2.0 parts of methyl acrylate. The reaction vessel was maintained at about 48 ° C and placed under a nitrogen atmosphere. About 0.1 part hydrogen peroxide and about 1.2 parts water were added in the course of about 2 hours., 5 hours, while maintaining the temperature at approximately 48 ° ± 3 ° C. About 0.03 parts of hydrogen peroxide and 0.3 parts of water were then added to reduce the residual monomer, followed by 0.2 part of sodium hydroxide and 0.6 part of water. The resulting sizing agent was an aqueous dispersion having 8.6% polymer solids formed and 11.4% stabilizing agent by weight, based on the total weight (ratio 0.75: 1). EXAMPLE 20 Preparative agents prepared as in Examples 19 and 17 were used to prepare paper by the general gelatin sizing process described above. The effectiveness of sizing was determined by means of the optical density test and by means of the color density test, each of them at sizing levels of 2 lb / ton and 4 lb / ton and carried out as described previously. The results are given below in Table 10 and show the effect of the variation of the comonomer content and the content of total monomers on the effectiveness of the sizing.

Table 10 Example 21 A sizing agent was prepared as follows: Approximately 0.1 part of water and 0.1 part of ferrous sulfate heptahydrate were added to about 75.3 parts of the stabilizing agent of Example B at about 58 ° C, followed by 6 hours. , 9 parts of styrene, 6.2 parts of n-butyl acrylate and 4.1 parts of methyl acrylate. The reaction vessel was cooled to about 48 ° C and placed under a nitrogen atmosphere. Approximately 0.5 part of hydrogen peroxide and about 4.7 parts of water were added in the course of about 2.5 hours, keeping the the same time the temperature at approximately 51 ° ± 3 ° C. About 0.03 parts of hydrogen peroxide and 0.3 parts of water were then added to reduce the residual monomer, followed by 0.3 parts of sodium hydroxide and 1.4 parts of water. The resulting squeezing agent was a dispersion Aqueous solution that had 17.2% polymer solids formed and 22.8% stabilizing agent by weight, based on total weight (ratio 0.75: 1). Example 22 Preparative agents prepared as in Examples 21 and 17 were used to prepare paper by the general gelatin-sizing process described above. The effectiveness of sizing was determined by means of the optical density test and by means of the color density test, each of them at a sizing level of 2 lbs / ton and carried out as described with anteriority. The results are given below i in Table 11 and show the effect of the variation of the content of comonomers and of the stabilizing agent content on the effectivity of the sizing. Table 11 Example 23 A sizing agent was prepared as follows: Approximately 56.6 parts of water and 0.1 part of ferrous sulfate heptahydrate were added to approximately 26.4 'parts of the stabilizing agent of Example B at about 68 ° C, followed by 4.8 parts of styrene, 4.3 parts of n-butyl acrylate and 2.9 parts of methyl acrylate. The reaction vessel was maintained at about 68 ° C and cooled under a nitrogen atmosphere. About 0.4 part of hydrogen peroxide and about 3.2 parts of water were added in the course of about 2.5 hours while maintaining the temperature at about 68 ° ± 3 ° C. Approximately 0.03 parftes of peroxide of Hydrogen and 0.3 parts of water to reduce the residual monomer, followed by 0.2 parts of sodium hydroxide and 0.8 parts of water. The resulting sizing agent was an aqueous dispersion having 12% polymer solids formed and 8% stabilizing agent by weight, based on total weight (ratio 1.5: 1). Example 24 Preparative agents prepared as in Examples 23 and 17 were used to prepare paper by the general procedure. gluing with gelatin. before described. The effectiveness of sizing was determined by means of the print quality test, by means of the ink penetration test, by means of the optical density test and by means of the color density test, each one of them at sizing levels of 2 lb / ton and 4 lb / ton and carried out as described above. The results are given below in Tables 12 and 13 and show the effect of the content variation on comonomers and of the stabilizing agent content on the effectiveness of sizing. Table 12 fifteen Table 13 Example 25 A priming agent was prepared as follows: Approximately 10.2 parts of water and 0.1 part of ferrous sulfate heptahydrate were added to about 63.0 parts of the stabilizing agent of Example C at about 58 ° C, followed by of 15.0 parts of styrene, 3.9 parts of n-butyl acrylate and 1.2 parts of methyl acrylate. The reaction vessel was maintained at about 58 ° C and placed under a nitrogen atmosphere. Approximately 0.4 parts of hydrogen peroxide were added and approximately 3.9 parts of water over the course of approximately 2.5 hours, while maintaining the temperature at approximately 58 ° + 2 ° C. Then, approximately 0.04 parts of hydrogen peroxide and 0.4 parts of water were added to reduce the residual monomer, followed by 0.4 parts of sodium hydroxide. and 1.2 parts of water. The resulting sizing agent was an aqueous dispersion having 20% polymer solids formed and 13.4% stabilizing agent by weight, based on the total weight (ratio 1.5: 1). Example 26 Staining agents prepared as in Examples 25 and 6 were used to prepare paper by the general gelatin sizing process described above. The effectiveness of sizing was determined by means of the print quality test (at 2 lb / ton and 4 lb / ton sizing levels) and by the ink penetration test (at ink sizing levels). 2 lb / ton and 4 lb / ton), as described above. The results are given below in Table 14 and show the effect of the variation of the comonomer content on the effectiveness of the sizing. Table 14 Example 27 The particle sizes of the precursor agents of Examples 2C and 17 were determined by transmission electron microscopy and by light scattering, as described above. Next, the results are shown in Table 16. These results show that the particle size and particle size distribution of the sizing agent of Example 17 are lower than those of the comparative sizing agent of Example 2C.

Table 16 Example 28C (Comparative) A sizing agent was prepared as follows: Approximately 0.4 part of ferrous sulfate heptahydrate was added to about 78.2 parts of the stabilizing agent of Example A at about 58 ° C, followed by 8.2 parts. of styrene and 9.5 parts of n-butyl acrylate. The reaction vessel was maintained at about 58 ° C and placed under a nitrogen atmosphere. Approximately 0.4 part of hydrogen peroxide and about 1.5 parts of water were added in the course of about 150 minutes while maintaining the temperature at about 60 ° ± 3 ° C. About 0.03 parts of hydrogen peroxide and 0.1 part of water were then added to reduce the residual monomer, followed by 0.3 parts of sodium hydroxide and 1.4 parts of water. The resulting sizing agent was an aqueous dispersion having 17.7% polymer solids formed and 15.8% stabilizing agent by weight, based on the total weight (ratio 1.12: 1). Example 29 Preparative agents prepared as in Examples 6, 8, 10, 12, 13 and 28C were prepared as previously described. During the preparation, the initiation time was determined by measuring the time elapsed between the time when the initiator was first added and i the moment when the temperature began to rise, as registered by a thermocouple inserted into the reaction mixture. The time necessary to reach the maximum temperature was also determined by measuring the time elapsed since the tempera- The temperature first began to rise until the temperature reached a maximum. Then, in Table 17, the initiation times and the necessary times are given until reaching the maximum temperature. These results demonstrate the best production rates that can be achieved by practicing the present invention.

Table 17 EXAMPLE 30 During the preparation of the precursor agents of Example 17 and 2C, monomer conversion was monitored as a function of time, as shown below in Table 19. These results show that the conversion is faster and more complete for Example 17 that for Comparative Example 2C. Table 19

Claims (20)

Claims

1. A method for preparing a sizing agent, consisting of 5 (I) forming a mixture composed of (A) 5-40% by weight, based on the total weight, of ethylenically unsaturated monomers, composed of (1) a 20-80 % molar, based on the total moles of monomers, of at least one monomer selected from the group consisting of styrene, styrene substituted with C 1 -C 4 alkyl, alkymethylstyrene and halogenated styrene in the ring; (2) 0-80 mole%, based on the total moles of monomers, of at least one monomer of C4-C2alkyl (meth) acrylate; (3) 5-50 mole%, based on the total moles of monomers, of at least one monomer 20 selected from the group consisting of methyl acrylate, ethyl acrylate and propyl acrylate, and (B) a stabilizing agent selected from the group consisting of ^^^^^ ^^^^^ g ^^^^^^^^^^^^ group consisting of polysaccharide and synthetic water-soluble polymer with a weight-average molecular weight of 1,000 or higher, where the ratio of said (A) said (B) in said mixture is in the range of about 0.6: 1 to about 1.7: 1 and wherein said mixture is substantially free of both (i) ethylenically unsaturated carboxylic and sulfonic acids and their salts and ( ii) emulsifier or surfactant with a molecular weight of less than 1,000, and (II) copolymerizing said ethylenically unsaturated monomers in the presence of water to form a dispersion.

2. A method as claimed in Claim 1, wherein said (1) is styrene, said (2) is butyl acrylate and said (3) is methyl acrylate.

3. A method as claimed in Claim 1, wherein said weight ratio of said (A) to said (B) in said mixture is in the range of about 0.8: 1 to about 1.5: 1.

4. A method as claimed in Claim 1, wherein the amount of said (1) is 40-60 mole% based on the total moles of monomers.

5. A method as claimed in Claim 1, wherein the amount of said (2) is 20-50 mol% based on the total moles of monomers.

6. A method as claimed in Claim 1, wherein the amount of said (3) is 10-20 mol% based on the total moles of monomers.

7. A method as claimed in Claim 1, wherein said stabilizing agent is a polysaccharide.

8. A method as claimed in Claim 1, further including the addition of a polymerization initiator at or near the end of said copolymerization to reduce the residual monomer content of said aqueous dispersion.

9. A sizing agent composed of (A) 5-40% by weight, based on the total weight, of a synthetic polymer composed of repetitive units of (1) 20-80 mol%, based on the total moles of repeating units , of at least one repeating unit selected from the group consisting of styrene, styrene substituted with C 1 -C 4 alkyl, alpha-methylstyrene and halogenated styrene in the ring; (2) 0-80 mole%, based on the total moles of repeating units, of at least one repeating unit of C 4 -C 2 alkyl (meth) acrylate; (3) 5-50 mole%, based on the moles of repeating units, of at least one repeating unit selected from the group consisting of methyl acrylate, ethyl acrylate and propyl acrylate, and (B) a stabilizing agent selected from the group consisting of polysaccharide and synthetic water-soluble polymer with a weight-average molecular weight of 1,000 or greater, ", Where the weight ratio of said (A) to said (B) in said squeezing agent is in the range of about 0.6: 1 to about 1.7: 1, where said squeezing agent is substantially free of emulsifier or surfactant with a molecular weight of less than 1,000 and wherein said synthetic polymer is substantially free of repetitive acid units.

10. A sizing agent as described in Claim 9, wherein said (1) is styrene, said (2) is butyl acrylate and said (3) is methyl acrylate.

11. A sizing agent as described in Claim 9 wherein said stabilizing agent is a cationic waxy corn starch.

12. A sizing agent as described in Claim 9, wherein said weight ratio of said (A) to said (B) in said sizing agent is in the range of from about 0.9: 1 to about 1.2: 1.

13. A sizing agent as described in Claim 9, wherein the amount of said (1) is 30-75 mole% based on the total moles of monomers.

14. A sizing agent as described in Claim 9, wherein the amount of said (2) is 10-60 mole% based on the total moles of monomers.

15. A sizing agent as described in Claim 9, wherein the amount of said (3) is 8-30 mol% based on the total moles of monomers.

16. A squeezing agent as described in Claim 9, wherein the amount of said (1) is 40-60%, the amount of said (2) is 20-50% and the amount of said (3) is 10 -20% molar based on the total moles of repetitive units.

17. A sizing agent as described in Claim 9, wherein said weight ratio of said (A) to said (B) in said sizing agent is in the range of about 0.8: 1 to about 1.5: 1 and where the amount of said (1) is 40-60%, the amount of said (2) is 20-50% and the amount of said (3) is 10-20% molar based on the total moles of units repetitive

18. A method for sizing the paper, consisting of (a) disposing of stock of paper, 5 (b) disposing of the sizing agent of Claim 9, (c) forming a framework with said stock of paper, and (d) mixing said squeezing agent. with said stock of paper or applying said priming agent to said lattice, in an effective amount to prepare the paper that is formed from said lattice.

19. A method as claimed in Claim 15 18, wherein said squeezing agent is applied to said lattice by a method selected from the group consisting of spraying and sizing press.

20. A method as claimed in Claim 20, wherein said paper that is formed from said lattice has a degree of sizing greater than the degree of sizing obtained when a sizing agent is used that does not contain repetitive units selected from the group consisting of in methyl acrylate, ethyl acrylate and propyl acrylate in place of the sizing agent of Claim 9.