KR19990035963A - Synthetic Cationic Polymer as Accelerator for Ace Sizing - Google Patents

Abstract

Synthetic cationic polymers are used as accelerators for alkenyl succinic anhydride sizing. The addition of certain synthetic cationic polymers reactive with alkenyl succinic anhydrides appears to improve the sizing efficiency of hydrophobic, cellulose sizing materials in papermaking. Synthetic cationic polymers replace starch as an effective promoter in papermaking.

Description

Synthetic Cationic Polymer as Accelerator for Ace Sizing

In the papermaking process, sizing agents are used to promote reduced water and ink absorption in paper products and to withstand aqueous acid and alkaline solutions. As used herein, the term “paper” is intended to include sheet-like lumps and moldings made from fibrous cellulose materials that can be derived from natural and synthetic sources.

Paper is often sized with various materials to increase resistance to water and other types of aqueous solutions. Such materials are referred to as size or sizing and they may be introduced during the actual papermaking process. Alternatively, the size or sizing can be applied to the finished web or sheet.

One example of a sizing agent is alkenyl succinic anhydride ("ASA"). ASAs useful for sizing cellulosic materials have had considerable commercial success in papermaking, especially as a replacement for conventional rosin-alum sizing systems. The use of ASA as a sizing agent is described in the literature; Farley and Wasser, "Sizing with Alkenyl Succinic Anhydride" in The Sizing of Paper, W.F. Reynolds, Ed., TAPPI, 1989, Chapter 3, are well known in the art. See also US Pat. No. 3,968,005, which is incorporated herein by reference.

ASA is insoluble in water and unstable in hydrolysis. Therefore, it must be emulsified in the paper mill prior to use. Specifically, the art requires the use of a sizing agent in parallel with a substance that is capable of producing cationic or one or more cations or other groups that are positively charged for retention. Emulsification is typically accomplished by passing ASA and protective colloids, starch and / or synthetic polymers through devices such as homogenizers, high shear turbine pumps, and the like.

Cationic starch plays several important roles in ASA sizing. First, it assists in the production of small particle size ASA emulsions. Small particle sizes in the micrometer range are required for good sizing efficiency. Second, it imparts good physical stability to the emulsion. Once added to the paper feed, the ASA emulsion should be stable to prevent deposition and press picking. Third, it retains emulsion on the fiber surface and promotes sizing efficiency. It has been found that as the amount of cationic starch in the pulp feed increases, the sizing level for a given amount of ASA increases several times. Usually, cationic starch is used at a ratio of 2 to 4 times that of ASA to give optimum sizing efficiency.

However, certain problems arise from the use of cationic starch. For example, starch must be cooked in a manufacturing plant, thus requiring large cooking equipment and storage tanks. More importantly, starch is biologically prone to degradation, thus causing the production of mucus and deposition in paper mill equipment, resulting in performance issues in the form of press picking, felting, filling and poor cylindrical density control.

In some cases, it may be desirable to function the ASA sizing system independently of cationic starch. Changes in starch viscosity and solids per batch, and the need to cool the starch prior to emulsification, can lead to undesired changes in ASA emulsion particle size. Some paper mills do not want to use starch due to difficult cooking and processing requirements. Other paper mills that are currently grading fine paper and using large amounts of ASA size require cationic starch for dry strength, but the paper mill prefers to use low-cost cationic corn starch. In general, more expensive cationic starch produces better results in ASA sizing.

As an alternative to cationic starch for ASA emulsification, in detail synthetic polymers have been studied to overcome the problems associated with cationic starch. As a substitute for starch, synthetic cationic polymers in the art do not react with ASA. For example, US Pat. No. 4,657,946 teaches improved emulsification of ASA sizing agents by using water-soluble vinyl addition polymers that are charged with cations. The '946 patent teaches paper sizing methods and emulsions using cationic charged, water soluble vinyl addition polymers and condensation polymers that provide improved emulsification of alkenyl succinic anhydride sizing agents. US Pat. No. 5,224,993 teaches saponification sizing agents for papers derived from dehydrating condensed alkenyl succinic anhydrides and organic carboxylic acids with polyalkylene polyamines and saponifying the remaining carboxyl groups with alkalis after dehydration condensation. US Pat. No. 4,629,655 teaches a size composition as a solid product produced by mixing a cationic polymer suitable to act as a size retention aid with a size suitable for sizing the substrate. Methods for sizing a substrate in the '655 patent include dispersing a solid in an aqueous mixture, applying the resulting mixture to a substrate, thereby allowing the size to be fixed to the substrate. However, synthetic cationic polymers in the art have been only slightly successful as a suitable substitute for starch. None of these synthetic cationic polymers contain functional groups that react with ASA. Synthetic cationic polymers in the art that serve as additives and co-emulsifiers for ASA sizing do not enhance sizing (or do not act as good promoters).

Various patents describing polymers reactive with ASA do not teach their use for promoting the efficiency of sizing agents. For example, this patent includes US Pat. No. 5,232,553, which teaches a papermaking process in which paper products obtained from pulp slurries use polyvinylamines containing fine particles of material. The '553 patent relates to the use of poly (vinylamine) and aldehydes to increase the retention of micromaterials in paper products.

In developing alternatives to starch in ASA emulsions, it has generally been found that the production of synthetic cationic polymers with high viscosity to act as retention aids to produce small particle size emulsions is not particularly difficult. The difficulty lies in the development of synthetic cationic polymers that promote the sizing efficiency of ASA by providing ASA reactive groups capable of immobilizing ASA on the fiber surface.

Various other patents use similar synthetic cationic polymers but do not teach an increase in sizing efficiency in papermaking. US Pat. No. 4,217,214 teaches the use of high molecular weight polyvinylamine hydrochloride for the aggregation of solids suspended in water purification or wastewater purification systems. US Pat. No. 4,957,977 teaches flocculants and paper strength enhancers using vinylamine copolymers and methods of producing vinylamine polymers. GB 2,268,758A has amine-functional poly (vinyl alcohol) and 4 or 5 membered cyclic esters or at least one alkyl or alkenyl substituent of at least 4 carbon atoms and at least a total of 8 carbon atoms in the substituent Teaching paper wet strength improvement by wet- or dry-end addition of cellulose reactive sizes, anhydrides with In fact, patents on synthetic cationic polymers in the art are not specifically related to increasing the efficiency of paper sizing.

Although synthetics in the art have had some success, it has been necessary in the paper industry to create more effective cationic agents useful as accelerators for sizing to avoid problems generally associated with cationic starch. Such cationic agents will be reactive with ASA and will significantly enhance sizing efficiency.

The present invention relates to emulsions using synthetic cationic polymers as accelerators for alkenyl succinic anhydride (ASA) sizing, more particularly emulsions containing alkenyl succinic anhydrides and synthetic cationic polymers to enhance sizing efficiency and use thereof. It is about a method.

Summary of the Invention

In the present invention, a papermaking method for improving the sizing efficiency of a hydrophobic cellulose sizing material comprising adding a synthetic cationic polymer reactive with the sizing material is provided. Groups reactive with ASA include primary amines and hydroxyls. Preferred sizing materials are alkenyl succinic anhydrides. Preferred synthetic cationic polymers include copolymers of primary amines. Also provided are synthetic cationic polymers containing one or more non-sizing reactive monomers, in particular non-ASA reactive monomers such as acrylic acid. For the purposes of the present invention, the term non-sizing reactive monomer (or non-ASA reactive monomer) means a monomer that does not cause significant reaction with the sizing material. The synthetic cationic polymer may be a copolymer of vinyl alcohol and vinylamine. The synthetic cationic polymer may also be a copolymer of acrylamide and vinylamine.

It also provides a papermaking method for improving the sizing efficiency of hydrophobic cellulose sizing materials comprising adding an effective amount of synthetic cationic polymer containing hydroxyl and / or primary amine groups to the cellulose sizing agent. Preferably the polymer comprises about 50 to about 99 mol% vinyl alcohol and about 50 to 1 mol% vinylamine.

A papermaking process for improving the sizing efficiency of alkenyl succinic anhydrides comprising adding a synthetic cationic polymer of about 20 to about 90 mol% acrylamide and about 80 to about 10 mol% vinylamine.

The present invention describes an alkaline sizing emulsion for improving sizing efficiency in papermaking comprising a hydrophobic cellulose sizing material and a copolymer of cationic vinylamine reactive with the sizing material. Preferably, the sizing material is alkenyl succinic anhydride. It is preferred to obtain as a copolymer comprising a synthetic polymer of about 20 to about 90 mole percent acrylamide and about 80 to about 10 mole percent vinylamine. It is also preferred to obtain as a copolymer comprising a synthetic polymer of about 50 to about 99 mol% vinyl alcohol and about 50 to about 1 mol% vinylamine.

Also provided is an alkaline sizing emulsion comprising an effective amount of a synthetic cationic polymer reactive with a sizing material, containing an alkenyl succinic anhydride sizing material and hydroxyl and / or primary amine groups.

As provided herein, the term “effective amount” is defined as the amount of material required to increase the sizing efficiency of the sizing agent.

Detailed Description of the Preferred Embodiments

Various synthetic cationic polymers are evaluated as replacements for the cationic starch commonly used in ASA paper sizing methods. Cationic starch has been shown to be a good sizing promoter for ASA.

To account for the effects of various synthetic cationic polymers on ASA sizing, the facilitation performance based on the increase in sizing efficiency using cationic starch is evaluated in comparison to various other synthetic cationic polymers. It should be noted that starch is distinct from synthetic cationic polymers because starch is a natural rather than synthetic material.

Paper handsheets containing the size and promoter are prepared and used for sizing evaluation. In the intention of the present invention, the handsheet consists of pulp, filler, sizing agent (ASA) and promoter (cationic starch or synthetic cationic polymer).

Emulsification of ASA Using Cationic Polyacrylamide

For each handsheet evaluation, the ASA emulsion is prepared in deionized water. The emulsification procedure proceeds as follows: 24.0 g of deionized water is weighed and placed in a small (about 35 ml capacity) stainless steel blender jar. Add about 1 g of ASA (weighed by difference) and run the blender at high speed for 5 minutes. Based on the calculated ASA concentration, the sample is immediately diluted to 0.25% with cold pH 3 deionized water to minimize hydrolysis. Samples are kept on ice until used for handsheet evaluation. The particle size was evaluated to be in the range of 1.5 to 2 μm.

Various synthetic cationic polymers containing amide and amine groups and copolymers of alcohol and amine groups are included within the scope of the present invention. Each polymer and copolymer is selected for evaluation because it contains functional groups (eg, primary amines or hydroxyls) that can react with ASA.

Cationic polyvinyl alcohol contains 6 mol% vinylamine groups (PVOH / PVA) and has a molecular weight ranging from 80 to 140 k daltons. The polymer is prepared by hydrolysis of a copolymer of vinyl acetate and N-vinyl formamide.

Polyvinylamine (PVA) and polyvinylamine. HCl (PVA / HCl) are believed to be useful in the present invention. PVA is low molecular weight and is supplied as a 12.8% solution. PVA.HCl may be a medium molecular weight powder.

Polyallylamine. HCl (PAA) and copolymers of allylamine and diallylamine.HCl (PAA / PDAA) are also contemplated as being useful in the present invention. PAA has an average molecular weight of about 100 k Daltons and is supplied as a 40% aqueous solution. PAA / PDAA has an average molecular weight of 50 k Daltons.

Hoffman decomposition of polyacrylamides using sodium hypochlorite introduces primary amines and carboxyl groups. Using four different molecular weight polyacrylamide samples ranging from 14 to 200 k Daltons using the procedure from Tanaka [H. Tanaka, J. Polymer Science: Polymer Letters Edition 16, 87-89 (1978)]. A sample containing about 40 mol% primary amine is prepared.

Table 1 shows the Hoffman decomposition products of polyacrylamides. Analysis of the amine and carboxyl content of Hoffmann's degradation products showed that the change in molecular weight did not significantly change the amine content, carboxyl content or isoelectric pH.

Example Molecular Weight (k Daltons) Mol% amine Mol% carboxyl Isoelectric pH One 200 40 14 9 2 77 47 24 9 3 47 60 24 8 4 14 47 14 8.5

In addition to ASA-reactive synthetic cationic polymers, various non-ASA-reactive synthetic cationic polymers, such as acrylamide / methacryloxyethyltrimethyl ammonium chloride (acrylamide / Q6) copolymers, polyethyleneimine (mostly 2 Polymers having an average molecular weight of from 50 to 60 k daltons), Mannich quaternary salts of polyacrylamide, and terpolymers of acrylamide, acryloxyethyltrimethylammonium chloride (Q9) and alkyl methacrylate Is considered as.

The predominantly used ASA is ACCOSIZE 18 (obtained from Cytec Industries Inc.).

Promotion of ASA Sizing

The sizing level achievable with ASA increases significantly (promotes) as the amount of cationic starch in the system increases. The magnitude of the increase and its sizing continue to increase even with the use of relatively large cationic starches with a ratio of starch to ASA of less than 3: 1. Because of this effect, high ratios of starch to ASA are used in current commercial practice. It does not matter whether the cationic starch is part of the ASA emulsion or added separately to the feed. As exemplified herein, the sizing level of the ASA sizing agent can also be significantly increased by increasing the concentration of synthetic cationic polymer that is reactive with ASA.

Handsheet Evaluation of Polymers as ASA Promoters

Handsheet experiments are performed using the following procedure. The feed is a 50/50 mixture of bleached hardwood and softwood kraft pulp at 500 Canadian Standard Freeness, with 15% by weight precipitated calcium carbonate and pH adjusted to 7.5. While stirring, batches of 0.6% consistency stocks containing 10 g of fiber are treated in the order of promoter, ASA emulsion of predetermined volume, followed by 1.0 lb / ton of anionic polyacrylamide retention aid. Allow 15 seconds of contact time between each addition. A 3-2.8 g handsheet (50 lb / Tappi ream) is formed, pressed to 1-1 / 2 weight and dried for 1 minute in a rotary drum dryer at 240 ° F.

After conditioning at 23 ° C. and 50% R.H. for at least 24 hours, the basis weight and sizing are measured on the sheet. Handsheets are tested for ink penetration using a sizing test of the type described in Tappi Standard T-530 pm-83. After one side of the paper is contacted with the ink, the time elapsed while the reflectance of the opposite side drops to 80% of the initial value is measured. The ink is as described in T-530 pm-83 but contains no formic acid and is buffered to pH 7. The test is normalized to a 50 lb / Tappi ream basis weight, assuming that the sizing is proportional to the cube of the basis weight.

While it is apparent that the invention described herein has been well calculated to describe the above-described invention, it should be understood that many variations and aspects can be modified by those skilled in the art, and the claims are intended to relate to the true spirit of the invention. It is intended to cover modifications and aspects falling within the scope.

Examples 5-14 (comparative)

Example 5 in Table 2 shows the evaluation results of the ink penetration of the ASA emulsion made with the 90/10 molar ratio AMD / Q6 copolymer. This same emulsion is then post-diluted with additional AMD / Q6 copolymer (synthetic cationic polymer) or cationic starch. The ASA dose is 0.15% fibrous in all examples. Post-dilution with additional AMD- / Q6 copolymers (Examples 6-9) indicate that the sizing efficiency does not increase significantly since the copolymer is not reactive with ASA. Examples 10-14 show that AMD / Q6 copolymers post-diluted with cationic starch provide a significant increase in sizing efficiency. As used herein, ink penetration is provided after a few seconds. This indicates that the increasing effect of sizing efficiency is due to cationic starch (ASA-reactive) and not to AMD / Q6 copolymer (which is non-ASA-reactive).

Example Cationic Polymer Roe Dilution (ratio to ASA) Dilution with cationic starch (ratio to ASA) Ink penetration (seconds) 5 (initial emulsion) 0.13 - 70 6 0.5 - 138 7 1.0 - 117 8 2.0 - 64 9 3.0 - 86 10 - 0.5 187 11 - 1.0 254 12 - 2.0 329 13 - 3.0 349 14 - 4.0 396

Examples 15-23 (comparative)

Table 3 shows evaluation results similar to those shown in Table 2. The 90/10 molar ratio AMD / Q6 copolymers of these examples are prepared by reverse tanning techniques. Example 15 shows the sizing obtained with ASA emulsion prepared using the AMD / Q6 copolymer. The ASA dose is 0.15% fibrous in all examples. This same emulsion is post-diluted with additional AMD- / Q6 copolymers (Examples 16-18)) or cationic starch (Examples 19-23). These examples (Examples 15-18) show that the addition of the reverse tanning AMD- / Q6 copolymer does not increase the sizing efficiency since the copolymer is not reactive with ASA. Examples 19-23 show that the reverse AMD / Q6 copolymer diluted with cationic starch provides a significant increase in sizing efficiency. It is shown that the increasing effect of sizing efficiency is due to cationic starch (ASA-reactivity) and not to AMD / Q6 copolymer (non-ASA-reactivity).

Example Post dilution with cationic polymer (ratio to ASA) Dilution with cationic starch (ratio to ASA) Ink penetration (seconds) 15 (initial emulsion) 0.13 - 62 16 0.5 - 78 17 1.0 - 35 18 2.0 - 11 19 - 0.5 130 20 - 1.0 189 21 - 2.0 257 22 - 3.0 290 23 - 4.0 340

Examples 24 to 32 (comparative)

Table 4 shows evaluation results similar to those shown in Tables 2 and 3. In this case, the synthetic cationic copolymer is AMD / Q6 at molar ratio 99/1. The ASA emulsion of Example 24 is prepared using only water. The ASA dose is 0.125% fibrous in all examples. This same emulsion is post-diluted with AMD- / Q9 copolymers (Examples 25-27) or cationic starch (Examples 28-32). This example shows that the addition of the AMD- / Q9 copolymer does not increase the sizing efficiency since the copolymer is not reactive with ASA. Post dilution with cationic starch provides a significant increase in sizing efficiency. It indicates that the effect of increasing the sizing efficiency is due to cationic starch (ASA-reactive) and not to AMD / Q9 copolymer (non-ASA-reactive).

Example Cationic Polymer Roe Dilution (ratio to ASA) Dilution with cationic starch (ratio to ASA) Ink penetration (seconds) 24 (initial emulsion) - - 6 25 0.5 - 8 26 1.0 - 4 27 2.0 - 5 28 - 0.35 40 29 - 0.6 77 30 - 1.2 89 31 - 2.4 157 32 - 4.8 179

Examples 33-41 (comparative)

Table 5 shows the evaluation results of the sizing as a function of accelerator capacity for the various accelerators. Each example of Table 5 is carried out using 0.2% fibrous of ASA. Examples 33 to 35 use an 18/20/2 mole% terpolymer of acrylamide / Q9 / n-dodecylmethacrylate terpolymer. This is a non-ASA reactive polymer. Examples 36 to 38 use cationic potato starch as promoter. Examples 39-41 use PVOH / PVA as promoter. Ink penetration is provided after a few seconds. This example shows that the facilitating effect of PVOH / PVA, ASA-reactive polymers increases the sizing efficiency by increasing the dose.

Example Capacity of cationic polymer (fibrous%) Ink penetration (seconds) 33 0.05 2 34 0.10 2 35 0.20 2 36 0.05 10 37 0.10 5 38 0.20 58 39 0.05 44 40 0.10 48 41 0.20 195

Examples 42-49 (comparative)

Table 6 shows the evaluation results of sizing as a function of accelerator capacity for various accelerators. Each example of Table 6 is carried out using 0.15% fibrous of ASA. Examples 42-45 use cationic potato starch as promoter. Examples 46-49 use PVOH / PVA as promoter. Other parameters of this analysis are similar to those of Table 5 (Examples 33-41). Table 6 shows that PVOH / PVA is more effective than cationic potato starch (over the range of 0.075 to 0.45 lb / ton). This example shows that accelerator efficiency is a function of accelerator concentration. PVOH / PVA is much more effective here than cationic potato starch when the concentration of cationic polymer (synthetic cationic polymer or starch) is about 0.45% fibrous.

Example Capacity of cationic polymer (fibrous%) Ink penetration (seconds) 42 0.075 160 43 0.15 157 44 0.30 194 45 0.45 222 46 0.075 251 47 0.15 269 48 0.30 315 49 0.45 214

Examples 50-55 (comparative)

Table 7 shows the evaluation results of sizing as a function of accelerator capacity for various promoters, as in Table 5 (Examples 33-41). The emulsions in Table 7 are prepared in the presence of PVOH / PVA or cationic potato starch at a ratio of 0.5 / 1 to ASA. After emulsification, additional PVOH / PVA or cationic starch is added to the feed to produce a fibrous 0.075, 0.15 or 0.3% capacity. Examples 50-52 use cationic potato starch as promoter. Examples 53-55 use PVOH / PVA, ASA-reactive polymers as promoters. This example illustrates that the accelerator efficiency is a function of the sizing concentration and the reactivity of the accelerator with the sizing material.

Example Capacity of cationic polymer (fibrous%) Ink penetration (seconds) 50 0.075 140 51 0.15 232 52 0.30 171 53 0.075 208 54 0.15 254 55 0.30 314

Examples 56-70 (comparative)

Table 8 shows the evaluation results of sizing as a function of accelerator capacity for various promoters, as in Table 6 (Examples 42-49). Examples 56-59 use polyethyleneimine as promoter. Examples 60-63 use Hoffman decomposition products as accelerators (Table 1, Example 1). Examples 67-70 use PVOH / PVA as promoter. This example shows that ASA-reactive synthetic cationic polymers (both PVOH / PVA and Hoffman degradation products) provide a facilitating effect on ASA sizing. Polyethylenimine that is non-ASA-reactive does not provide a promoting effect.

Example Capacity of cationic polymer (fibrous%) Ink penetration (seconds) 56 0.075 2 57 0.15 4 58 0.30 2 59 0.45 2 60 0.075 28 61 0.15 92 62 0.30 242 63 0.45 184 64 0.075 111 65 0.15 144 66 0.45 282 67 0.075 225 68 0.15 285 69 0.30 434 70 0.45 350

Examples 71-82 (comparative)

Table 9 shows the evaluation results of sizing as a function of accelerator capacity for various promoters, as in Table 6 (Examples 42-49). The dose of ASA is 0.2% on dry fibres. Examples 71-73 use Mannich quaternary salts of polyacrylamide as accelerators. Examples 74-76 use cationic potato starch as promoter. Examples 77-79 use PVOH / PVA as promoter. Examples 80-82 use Hoffman decomposition products as promoters (Table 1, Example 1). This experiment shows that two ASA-reactive synthetic cationic polymers (PVOH / PVA and Hoffman degradation products) provide a facilitating effect on sizing. Mannich quaternary salts of non-ASA-reactive polyacrylamides do not provide a promoting effect.

Example Capacity of cationic polymer (fibrous%) Ink penetration (seconds) 71 0.075 2 72 0.15 2 73 0.30 2 74 0.15 7 75 0.30 24 76 0.45 101 77 0.0375 40 78 0.075 45 79 0.15 129 80 0.075 73 81 0.15 72 82 0.30 177

Examples 83-106 (comparative)

Table 10 shows the evaluation results of sizing as a function of accelerator capacity for various promoters, as in Table 6 (Examples 42-49). Fibrous 0.15% ASA is used. Examples 83-85 use PAA / PDAA of 50 k Dalton molecular weight as promoter. Examples 86-88 use PAA of 100 k Dalton molecular weight as promoter. Examples 89-91 use Hoffman decomposition products (Table 1, Example 4) of 14 k Dalton molecular weight as accelerators. Examples 92-94 use Hoffman decomposition products (Table 1, Example 3) of 47 k Dalton molecular weight as accelerators. Examples 95-97 use Hoffman decomposition products (Table 1, Example 2) of 77 k Dalton molecular weight as accelerators. Examples 98 to 100 use Hoffman decomposition products (Table 1, Example 1) of 200 k Dalton molecular weight as accelerators. Examples 101-103 use cationic potato starch as promoter. Examples 104-106 use PVOH / PVA as promoter. This example shows that the facilitating effect of Hoffman degradation products increases with increasing molecular weight. This example also shows that the facilitating effect of Hoffman degradation products increases with increasing sizing agent along with the sizing material.

Example Capacity of cationic polymer (fibrous%) Ink penetration (seconds) 83 0.075 11 84 0.15 40 85 0.30 29 86 0.075 2 87 0.15 One 88 0.30 3 89 0.075 2 90 0.15 One 91 0.30 7 92 0.075 2 93 0.15 2 94 0.30 2 95 0.075 15 96 0.15 20 97 0.30 111 98 0.075 71 99 0.15 194 100 0.30 236 101 0.15 236 102 0.30 312 103 0.45 373 104 0.075 308 105 0.15 491 106 0.30 389

Examples 107 to 130 (comparative)

Table 11 shows the evaluation results of sizing as a function of accelerator capacity for various promoters, as in Table 10 (Examples 83-106). Examples 107-109 use Hoffman decomposition products of 14 k Dalton molecular weight (Table 1, Example 4) as promoters, and Examples 110-112 use Hoffman decomposition products of 47 k Dalton molecular weight (Table 1, Example) as accelerators. Use 3). Examples 113-115 use Hoffman decomposition products (Table 1, Example 2) of 77 k Dalton molecular weight as accelerators. Examples 116-118 use a 200 k Dalton molecular weight (Table 1, Example 1) Hoffman decomposition products as promoters. Examples 119-121 use PVA as an accelerator. Examples 98-100 use a 200 k Dalton molecular weight (Table 1, Example 1) Hoffman decomposition products as promoters. Examples 119-121 use PVOH / PVA as promoter. Examples 128-130 use cationic potato starch as promoter. This example shows that PVA and PVA.HCl are effective promoters for ASA. It is also shown that PVOH / PVA is an effective promoter and that the efficiency of Hoffman degradation products increases with increasing molecular weight.

Example Capacity of cationic polymer (fibrous%) Ink penetration (seconds) 107 0.30 4 108 0.45 5 109 0.60 60 110 0.30 One 111 0.45 One 112 0.60 One 113 0.15 6 114 0.30 24 115 0.45 127 116 0.075 194 117 0.15 153 118 0.225 240 119 0.15 258 120 0.30 449 121 0.45 260 122 0.15 129 123 0.30 477 124 0.45 406 125 0.0375 178 126 0.075 280 127 0.15 337 128 0.15 108 129 0.30 334 130 0.45 326

Examples 131 to 154 (comparative)

Table 12 shows further comparative evaluation of PVOH / PVA as sizing promoter for ASA. The performance of PVOH / PVA polymers as sizing promoters is comparable to the use of cationic starch as accelerators. The synthetic polymers are evaluated while varying the mole percent of PVA in the PVA / PVOH polymer and also changing the molar weight and capacity of the PVA / PVOH polymer. Each evaluation is performed using 0.15 mole percent fibrous of ASA. The higher the PVA mole% content, the more effective the PVA / PVOH promoter was than the cationic starch. At PVA levels of 3 mol% or less, the copolymer is not effective as an accelerator. It was also shown that higher efficiency yields higher molecular weight samples.

Example PVA (mol%) Cationic starch (fibrous%) Molar weight (k Daltons) Capacity (fibrous%) Ink Penetration (sec) 131 <1 - 50-120 0.15 One 132 <1 - 50-120 0.30 One 133 <1 - 50-120 0.45 One 134 3 - 50-120 0.15 One 135 3 - 50-120 0.30 One 136 3 - 50-120 0.45 One 137 6 - 36 0.0375 5.5 138 6 - 36 0.075 21 139 6 - 36 0.15 48 140 6 - 95 0.0375 One 141 6 - 95 0.075 23 142 6 - 95 0.15 98 143 6 - 80-140 0.0375 47 144 6 - 80-140 0.075 119 145 6 - 80-140 0.15 378 146 18 - 75 0.0375 30 147 18 - 75 0.075 259 148 18 - 75 0.15 204 149 - 0.15 - - 34 150 - 0.15 - - 13.6 151 - 0.30 - - 239 152 - 0.30 - - 271 153 - 0.45 - - 275 154 - 0.45 - - 540

Examples 155-159 (comparative)

The paper used in the examples in Table 13 was prepared on a pilot paper machine. ASA is emulsified with a copolymer of acrylamide / methyl chloride quaternary salt of dimethylaminoethyl methacrylate (AMD / Q6) or cationic potato starch. The emulsion is added to the pulp at the down leg of the raw material box. The ASA dose is kept constant at 0.175%. The feed is hardwood / softwood 70/30 bleached with 25% addition precipitated CaCO ₃ . In Example 155, the AMD / Q6 copolymer is provided at a final ratio of 0.13 / 1 for ASA. In Example 156, the total AMD / Q6 copolymer is provided as in Example 155, but additional polymer is added so that the final ratio of AMD / Q6 to ASA is 1.0 / 1. In Example 157, the ASA emulsion is prepared using a 90/10 AMD / Q6 reverse emulsion copolymer with a final polymer / ASA ratio of 0.13 / 1. The results of these three examples show that the average sizing for Examples 155, 156 and 157 is 20, 41 and 5 seconds, respectively. This indicates that the sizing is low for standard emulsions. Increasing the copolymer level from 0.13: 1 to 1: 1 causes only a small increase in sizing. This shows that when the polymer does not react with the sizing material, the synthetic cationic polymer does not impart sizing (or increase sizing efficiency). In comparison, Examples 158 and 159 are ASA emulsions prepared at a ratio of 2.1 / 1 to ASA using cationic starch. Much higher sizing values show the facilitating effect of ASA reactive cationic starch.

Example Ratio of cationic starch Ratio of cationic polymer Ink Penetration (sec) 155 - 0.13 20 156 - 1.0 41 157 - 0.13 5 158 2.1 - 225 159 2.1 - 219

Claims (10)

Papermaking process for improving the sizing efficiency of alkenylsuccinic anhydride comprising adding a synthetic cationic polymer reactive with anhydride. The method of claim 1 wherein the cationic polymer comprises a copolymer of primary amines. The method of claim 1 wherein the cationic polymer is a copolymer of about 50 to about 99 mol% vinyl alcohol and about 50 to 1 mol% vinylamine. The method of claim 1 wherein the cationic polymer is a copolymer of about 20 to about 90 mole percent acrylamide and about 80 to 10 mole percent vinylamine. A papermaking method for improving the sizing efficiency of a hydrophobic, cellulose sizing material comprising adding an effective amount of a synthetic cationic polymer containing hydroxyl or primary amine groups to a cellulose sizing agent. A papermaking method for improving the sizing efficiency of alkenylsuccinic anhydride comprising adding a synthetic cationic polymer comprising from about 50 to 99 mol% vinyl alcohol and from about 50 to about 1 mol% vinylamine. A papermaking process for improving the sizing efficiency of alkenylsuccinic anhydride comprising adding a synthetic cationic polymer of about 20 to about 90 mol% acrylamide and about 80 to about 10 mol% vinylamine. A. alkenylsuccinic anhydrides; And B. Alkaline sizing emulsion for improving sizing efficiency in papermaking comprising a copolymer of cationic vinylamine reactive with a sizing material. The alkaline sizing emulsion of claim 8 wherein the synthetic polymer comprises a copolymer of about 20 to about 90 mole percent acrylamide and about 80 to about 10 mole percent vinylamine. The alkaline sizing emulsion of claim 8 wherein the synthetic polymer comprises a copolymer of about 50 to about 99 mol% vinyl alcohol and about 50 to about 10 mol% vinylamine.