Paper sizing composition

[0001] The present invention relates to the improvement of paper sizing with aqueous dispersions of ketene dimers and the dispersion stability of ketene dimers containing vinylamine-containing polymers.

BACKGROUND OF THE INVENTION [0002] Weisgerber (US 2,961,366) describes the use of polyvinylamine to improve retention of ketene dimer by paper fibers, where increased retention increases the amount of sizing. In his document, Weisgerber indicates that polyvinylamine can be added separately from the sizing agent to the pulp suspension, however, the preferred way to add it is to add the ketene dimer to the aqueous emulsion immediately before adding the ketene dimer to the paper machine.

[0003] Speaking of adding polyvinylamine to the ketene dimer aqueous emulsion immediately before adding the emulsion to the paper machine, Weisgerber is not concerned with the long-term stability of the blend. However, for water-based alkyl ketene dimer emulsions to be economically viable, they must be stable for a long time. Aqueous ketene dimer emulsions must be both physically and chemically stable. Physical stability means a sufficiently stable viscosity, so that the emulsions remain pumpable and diluted until added to the paper machine. Chemical stability means maintaining the ketene dimer content of the emulsion at a high level until added to the paper machine.

[0004] The physical stability of ketene dimer emulsions is the subject of many patents. For example, Edwards et al. (US 4,861,376) disclose that the combination of small amounts of low molecular weight carboxylic acids with cationic starch, sodium lignosulfonate and aluminum sulfate increases the colloidal stability of the ketene dimer dispersion to over four weeks at 32 ° C. Schmid et al. (US2008 / 0041546 A1) further disclose stable compositions for sizing reactive sizing agents. The emulsions of their invention are stabilized with a cationic starch mixture having a DS value> / = 0.05, an anionic dispersant and a linear nitrogen-containing polymer. Although their physical stability is demonstrated, chemical stability is not discussed.

[0005] Stable starch-stabilized ketene dimer dispersions are well known in the industry, see for example US 4,861,376, for Edwards et al. Or US 4,964,915, for Blixt, et al. Simple blends of such starch-stabilized ketene dimer dispersions with commercially available polyvinylamine physically unstable products that gel in a few minutes. Mixtures of starch-stabilized ketene dimer and polyvinylamine dispersions whose pH has been adjusted as disclosed in US2008 / 0041546 A1 are also physically unstable and solidify on storage (see example US 52008/0041546 A1).

SUMMARY OF THE INVENTION [0006] It has been found that ketene dimer dispersions containing vinylamine-containing polymers such as polyvinylamine that are both physically and chemically stable can be prepared by simply adding vinylamine-containing polymer to the ketene dimer dispersion with appropriate pH adjustment polymer containing vinylamine. Stable blends are obtained using vinylamine-containing polymers such as polyvinylamine whose pH has been adjusted to below 3.3. It has further been found that conditioning such sizing compositions for some time before adding to the paper machine can improve sizing performance.

[0007] A paper sizing composition is disclosed. This composition contains a dispersion of ketene dimer and a pH-corrected vinylamine-containing polymer that are stable and provide increased sizing efficiency, wherein the pH of the pH-corrected vinylamine-containing polymer is lower than 3.3.

[0008] A method for preparing a permanent sizing composition is disclosed. This method includes 1) adjusting the pH of the vinylamine-containing polymer to below 3.3, and 2) mixing the pH-corrected vinylamine-containing polymer with a ketene dimer dispersion.

[0009] A method of sizing paper is disclosed. This method includes 1) adjusting the pH of the vinylamine-containing polymer to a value below 3.3, 2) mixing the pH-corrected vinylamine-containing polymer with a ketene dimer dispersion, 3) maintaining the vinylamine-containing polymer blend and ketene dimer dispersion for at least one hour; and 4) adding the vinylamine-containing polymer blend and ketene dimer dispersion to the pulp suspension in the papermaking process or applying in a size press.

[0010] In a preferred embodiment of the invention, the ketene dimer dispersion is a starch-stabilized ketene dimer dispersion.

DETAILED DESCRIPTION OF THE INVENTION [0011] The present invention relates to paper sizing compositions containing ketene dimer dispersions and a vinylamine-containing polymer, such as polyvinylamine, which are stable and provide increased sizing performance. Stable paper sizing compositions include a vinylamine-containing polymer, a dispersant system, and an alkyl ketene dimer. Such sizing compositions are obtained by 1) adjusting the pH of the polymer to less than 3.3 before mixing with the ketene dimer dispersion, and then 2) mixing the polymer with the ketene dimer dispersion, and 3) optionally conditioning this blend before entering the paper machine to obtain optimal sizing parameters. The ketene dimer dispersion is preferably stabilized by starch.

[0012] The sizing compositions of the present invention are both physically and chemically stable. For the purposes of this patent, a dispersion is considered to be physically stable if its viscosity does not exceed 4 g / cm 3 s (400 cps) when stored for 4 weeks at 32 ° C. The dispersion is considered to be chemically stable if the reduction in content does not exceed 10% over the same storage period for 4 weeks at 32 ° C. Content means the amount of ketene dimer in the initial emulsion formulation. The ketene dimer may react with water over time to form a compound usually referred to as diketone, resulting in a reduction in content. Diketon is not an effective sizing agent, so it is desirable that the losses are as low as possible.

[0013] Examples of diketones include 16-hentriacontanone, dipentadecyl ketone, palmiton, pentadecyl ketone, 18-pentatriacontanone, di-n-heptadecyl ketone, diheptadecyl ketone, heptadecyl ketone, stearon and mixtures thereof.

[0014] Any of the ketene dimers known in the art can be used in the method of the present invention. Ketene dimers used as sizing agents are dimers with the following formula:

R1-CH = C-CH-R2 ii

OC = O wherein R1 and R2 are alkyl radicals which may be saturated or unsaturated and have from 6 to 24 carbon atoms, preferably more than 10 carbon atoms and most preferably from 14 to 16 carbon atoms. R1 and R2 may be the same or different. Such ketene dimers are well known, for example from US Patent No. 2,785,067.

[0015] Suitable ketene dimers include decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, eicosyl, docosyl, tetracosyl, ketene dimers, as well as ketene dimers derived from palmitoleoleic acid, oleic acid, ricinoleoleic acid, ricinoleoleic acid Eleostearic acid. The ketene dimer may be a single substance or may contain a mixture of substances. The most preferred ketene dimers are alkyl ketene dimers obtained from linear, natural, C12-C22 saturated fatty acids, oleic acid, isostearic acid or mixtures thereof.

[0016] Suitable ketene dimers used as sizing agents are also known as: 4-heptadecylidene-3-hexadecyl-2-oxetanone; 2-hexadecyl-3-hydroxy-3-eicosenoic acid, β-lactone (6Cl); cetyl ketene dimer; hexadecyl ketene dimer; palmitylketene dimer; 4-heptadecylideno-3-tetradecyl-2-oxetanone; 3-hexadecyl-4-pentadecylideno-2-oxetanone; 4-pentadecylideno-3-tetradecyl-2-oxetanone; myristyl ketene dimer; tetradecylketene dimer; 4- (15-metyloheksadecylideno) -3- (14-metylopentadecylo) -2-oxetanone; isostearyl ketene dimer; 4- (8Z) -8-heptadecen-1-ylidene-3- (7Z) -7heksadecen-1-yl-2-oxetanone; 4- (8-heptadecenylideno) -3- (7-heksadecenylo) -2-oxetanone; 4- (8Z) -8-heptadecenylidene-3- (7Z) -7-hexadecenyl-2-oxetanone (9Cl); olein ketene dimer and mixtures thereof.

[0017] Starch-stabilized ketene dimer dispersions are well known in the art. Such dispersions contain cationic starch, anionic dispersant and may contain some aluminum sulfate or polyaluminium salt. Cationic starch is any water-soluble starch that contains a sufficient number of cationic amino groups for the starch to be positively charged in solution. The degree of substitution is preferably less than 0.05 and more preferably less than 0.048 and greater than 0.042. Preferred starches are cationic waxy maize starches with quaternary amine groups as a charge source, such as StaLok 169 (available from Tate & Lyle). Suitable anionic dispersants include lignosulfonates, polynaphthalenesulfonates and polymers containing styrene sulfonate. Sodium lignosulphonate is preferred. Examples of such dispersions are given in US Patent No. 4,964,915, for Blixt et al., In US Patent No. 4,861,376, for Edwards et al. And in US Patent No. 3,223,544 for Savina.

[0018] The pH of the starch-stabilized ketene dimer emulsion used in the present invention is preferably less than 5.0, more preferably less than 4.5, and most preferably is 4.3 or lower.

[0019] The term emulsion technically means a two-phase system with liquid droplets in a continuous liquid medium, and the term dispersion means a two-phase system with solid particles in a continuous liquid medium. The physical state of the alkyl ketene dimer depends on the system temperature and the fatty acids used to prepare the ketene dimer; The alkyl ketene dimer in commercially available sizing agents may be liquid or solid. As a result, both terms are used interchangeably with commercially available sizing agents in the industry and in this patent.

[0020] These emulsions may contain other additives typical of sizing emulsions, such as biocides, defoamers etc.

[0021] The term "vinylamine-containing polymers" is intended to mean homopolymers of vinylamine (eg, polyvinylamine or fully hydrolyzed polyvinylformamide), copolymers of vinylamine with other comonomers, partially hydrolyzed polyvinylformamide, partially hydrolyzed vinylformamide copolymers, vinylpolymer homopolymerized copolymers acrylamide polymers. Examples of such polymers are given in US Patent No. 6,159,340 to Niessner et al.

[0022] The vinylamine-containing polymer used in the methods of the present invention is preferably selected from the group consisting of a vinylamine homopolymer (i.e. polyvinylamine) vinylamine copolymers, vinylamine terpolymers, vinylamine homo- and copolymers produced by Hofmann modification of acrylamide polymers or chemically modified vinylamine polymers after polymerization. The vinylamine-containing polymer used in the methods of the present invention is most preferably polyvinylamine.

[0023] The molecular weight of the polymers of the present invention is important for their use as additives in the production of paper. If the molecular weight is too low, the polymer may be weakly retained on the fibers of the pulp. If the molecular weight is too high, the polymer tends to coagulate before binding to the fiber, resulting in reduced polymer efficiency. The molecular weight (Mw) of the vinylamine-containing polymers used in carrying out the present invention ranges from 4000; 10000; 20000; 50000; 75000; 100000; 150,000 or 200,000 to 400,000; 450000; 500000; 600000; 700000; 800,000 or 1,000,000; preferably from 4,000 to 1,000,000 daltons, more preferably from 10,000 to 1,000,000 daltons, more preferably in the range from 20,000 to 800,000 daltons, more preferably in the range from 50,000 to 700,000 daltons, more preferably in the range from 75,000 to 600,000 daltons, more preferably in the range from 100,000 to 500,000 daltons. more preferably in the range of 150,000 to 450,000 daltons and most preferably in the range of 200,000 to 400,000 daltons.

[0024] The vinylamine-containing polymer used in the methods of the present invention may be fully or partially hydrolyzed polyvinylformamide. The percent hydrolysis of polyvinylformamide, for example, to prepare the vinylamine-containing polymers used in carrying out the present invention ranges from 10; twenty; thirty; 40 or 50 to 60; 70; 80; 90 or 100; preferably from 30 to 100%, more preferably from 40 to 100%, more preferably in the range from 50 to 100%, more preferably in the range from 60 to 100%, more preferably in the range from 70 to 100%, more preferably in the range from 80 to 100, most preferably in the range from 90 to 100%.

[0025] In addition to primary amine moieties, partially hydrolyzed polyvinylformamide and vinylamine copolymers usually contain randomly distributed amidine functional groups. The level of amidine functional groups depends on hydrolysis conditions such as time, temperature, corrosive content and other factors.

[0026] In order to obtain the sizing composition of the present invention, the pH of a vinylamine-containing polymer, such as polyvinylamine, must first be adjusted to a stable value below 3.3. A pH below 3.0, more preferably below 2.5 is preferred, and a pH of 2.1 to 2.5 is most preferred. The pH-corrected vinylamine-containing polymer must be a transparent, homogeneous solution. The pH adjustment can be carried out with mineral or organic acids. The preferred acid for such a pH correction is hydrochloric acid, which produces transparent, homogeneous solutions at a target pH value. The use of sulfuric acid, for example, gives a heterogeneous polyvinylamine solution that is unusable. Organic acids (e.g. formic acid) can also be used. Other commercially available acids include methylsulfonic acid, hydrobromic acid, phosphoric acid and nitric acid.

[0027] The pH-corrected polymer is added to the dispersion of the ketene alkyl dimer with vigorous stirring at a level that allows obtaining adequate sizing parameters. A level of 0.5% to 100% polymer relative to the alkyl ketene dimer may be used. A level of 5% to 50% polymer relative to the alkyl ketene dimer is preferred. A higher level of polymer provides a higher level of adhesive formation. The pH of the final emulsion should be lower than 3.

[0028] The sizing compositions of the present invention can be used immediately, however, it has been found that optimal sizing parameters for mixtures are obtained if they are held or conditioned for several hours before use. Conditioning the sizing composition significantly increases the amount of adhesive formed for a given amount of the alkyl ketene dimer and polymer, which greatly increases the sizing efficiency. The minimum holding time for conditioning the composition is preferably one hour and more preferably three hours. The holding time is preferably from 3 hours to 8 hours. The composition can be kept for more than 8 hours. Retention time exceeding 8 hours does not give a significant additional improvement in parameters.

[0029] The sizing agents obtained by the present invention can be used for mass sizing in which the sizing dispersions are added to the pulp suspension at the wet end of the papermaking process, or surface sizing in which the sizing dispersions are used in a press for sizing or in a coating machine. The present invention may further be used in one or both parts of a two-part sizing system. For example, one part can be mixed with pulp and the other part can be used in a size press, which is typical practice in paper production.

[0030] The amount of sizing agent added in bulk or used as surface adhesive is from 0.005 to 5% by weight of the reactive sizing agent relative to the dry weight of the charge, i.e. fibers and optionally filler, and preferably from 0.01 to 1% by weight. The dose depends mainly on the quality of the pulp or paper to be sized, the sizing compound used and the desired sizing level. [0031] Chemicals conventionally added to the charge in the production of paper or cardboard, such as processing aids (e.g. retention agents, drainage agents, anti-pollution additives etc.) or other functional additives (e.g. additives providing wet or wet strength) (dyes, optical brighteners, etc.) can be used together with the sizing agents of the present invention.

EXAMPLES [0032] The following examples are given to illustrate the present invention. Unless otherwise stated, all parts and percentages are based on weight. [0033] In the following examples, sizing was assessed using a semi-technical scale paper machine designed for the simulation of an industrial flat-screen machine, including batch preparation, comminution and storage. The charge was fed by gravity from the machine box to a constant level feed tank. From it, the charge was pumped into a series of built-in mixers, in which additives were introduced at the wet end, and then to the mass pump. The batch was diluted with white water on a mass pump to a solids content of 0.2%. Further chemicals can be added to the charge fed to or leaving the mass pump. The charge was pumped from the main mass pump to the additional mass pump, in which chemicals could be added to the input, and then to the flow spreader and the stacking bar on which it was deposited on a 12-inch wide screen. Immediately after settling onto the sieve, the sheet was vacuum dehydrated using three vacuum boxes; the density on the wringing press was 14-15%. [0034] The wet sheet was transferred from the wringing press to the motorized wet receiving felt. At this point, the water was removed from the sheet and felt under vacuum using Uhle felt suction cups fed from a vacuum pump. The sheet was further dehydrated on a single-felt press; it left the press section with a solids content of 38 - 40%. [0035] An assessment was made in a simulated pulp for recycling cardboard, using a mixture of recycled charge (80%) and recycled newsprint (20%) with a lean weight in standard Canadian units of 350 cm³ with 2.75% sodium lignosulphonate added to simulate anionic impurities. Hardness and basicity were 126 ppm and 200 ppm, respectively. The addition levels for all additives are in weight percentages relative to dry pulp. 0.3% cationic corn starch horse tooth (Sta-Lok 300, Tate & Lyle) was added to the thick stock before adding the sizing agent. No other additives were used at the wet end. The batch temperature was maintained at 55 ° C. The infusion box pH was controlled at 7.5 using a strong base.

[0036] A sheet of 171 g / m2 was produced² (ream 105 lb / 3000 ft²) and dried in seven drying chambers to a water content of 7% (surface temperature of the drying chamber 90 ° C) and passed through a single pressure roller of a smoothing machine with 5 pressure rollers and 6 rollers. Sizing was measured by the HST and Cobb method on a naturally conditioned board in an air-conditioned room (50% WW, 25 ° C) for at least 7 days.

[0037] AKD emulsion: Hercon® 100 sizing agent, cationic alkyl dimer emulsion stabilized with cationic starch (Hercules Incorporated, Wilmington DE). The required pH for this product is 2.1 - 4.2.

[0038] Polyvinylamine 1: a cationic polymer obtained by hydrolysis of poly-N-vinylformamide with a degree of hydrolysis of 100%. The polymer contains vinylamino, amidine and vinylformamide groups. Available from Hercules Incorporated as Hercobond® 6363 (Hercules Incorporated, Wilmington DE).

[0039] Polyvinylamine 2: a cationic polymer obtained by hydrolysis of poly-N-vinylformamide with a degree of hydrolysis of 50%. The polymer contains vinylamino, amidine and vinylformamide groups. Available from Hercules Incorporated as Hercobond® 6350 (Hercules Incorporated, Wilmington DE).

[0040] Example 1: Adjusting the pH of the polymer to a low pH ensures the stability of the pH correction of the blend in the case of polyvinylamine resin:

[0041] 35% HCl was slowly added to polyvinylamine 1 with vigorous stirring. As HCl was added, the pH was monitored. The amount of HCl added was corrected to obtain the appropriate target pH. The pH was checked again after a few hours to see if it was stable. Corrected as necessary with additional acid or polymer to obtain the target pH.

Preparation of the mixture:

[0042] pH corrected polyvinylamine was slowly added to the starch-stabilized AKD emulsion with stirring. An amount of pH corrected polyvinylamine was added to obtain a 12.5% ​​polymer relative to the alkyl ketene dimer.

[0043] The physical and chemical stability of these mixtures was determined immediately after receipt and after conditioning for 2 and 4 weeks in an oven at 32 ° C. Viscosity was used as a measure of physical stability. Viscosity was measured using a Brookfield viscometer at 60 rpm using a suitable spindle. Chemical stability was determined by the infrared method to determine the level of active ketene dimer in emulsions.

Table 1. Effect of polymer pH on the physical and chemical stability of the sizing composition using hydrochloric acid for pH correction.

<td></td><td colspan="3">Physical persistence</td><td colspan="4">Chemical stability</td>

<td>pH PVAm after correction</td><td colspan="3">Brookfield viscosity at 60 rpm</td><td colspan="4">Dimer content</td>

<td></td><td>p^aboutreceiving g / cm ^ s (Cps)</td><td>2 weeks at 32 ° C g / cnrs (cps)</td><td>4 weeks at 32 ° C g / cm ^ s (cps)</td><td>p^aboutreceipt (% wt)</td><td>2 weeks at 32 ° C (weight%)</td><td>4 weeks at 32 ° C (weight%)</td><td>reduction content %</td>

<td> 2,1</td><td> 0,96 (96)</td><td> 1,3 (130)</td><td> 1,18 (118)</td><td> 10,4</td><td> 10</td><td> 9,6</td><td> 8%</td>

<td> 2,5</td><td> 0,76 (76)</td><td> 1,08 (108)</td><td> 0,96 (96)</td><td> 10,2</td><td> 9,6</td><td> 9,4</td><td> 8%</td>

<td> 2,9</td><td> 1,24 (124)</td><td> 1,69 (169)</td><td> 1,76 (176)</td><td> 10,4</td><td> 10,0</td><td> 9,5</td><td> 9%</td>

<td> 3,3</td><td> 2,6 (260)</td><td> 4,48 (448)</td><td> 3,88 (388)</td><td> 10,6</td><td> 9,8</td><td> 9,4</td><td> 11%</td>

<td> 3,7</td><td> 3,75 (375)</td><td> 5,22 (522)</td><td>(582); some gel</td><td> 10,7</td><td> 9,80</td><td> 9,6</td><td> 10%</td>

<td> 5,0</td><td> 3,12 (312)</td><td>gelation</td><td>5.82 gelation</td><td> 10,9</td><td> 8,80</td><td> --</td><td> 19%</td>

<td>No correction</td><td>gelation</td><td> --</td><td> --</td><td> --</td><td> --</td><td> --</td><td> --</td>

[0044] It is undoubtedly that at pH 3.3 and higher, there was an increase in viscosity and loss of physical stability of emulsions containing PVAm resin ("polyvinylamine"). Chemical stability was low at pH 5. It is preferable to correct the PVam value to 3.0 before mixing with the ketene dimer.

[0045] Example 2: Organic acids can also be used to adjust the pH.

[0046] The pH adjustment of the resin and preparation of the mixtures was carried out in the same way as in Example 1, however, formic acid was used instead of hydrochloric acid.

Table 2. Effect of polymer pH on the physical and chemical stability of the sizing composition using formic acid for pH correction.

<td></td><td colspan="3">Physical persistence</td><td colspan="4">Chemical stability</td>

<td></td><td colspan="3">Brookfield viscosity at 60 rpm</td><td colspan="4">Dimer content</td>

<td>pH PVAm after correction</td><td>p^aboutreceiving g / cm ^ s (Cps)</td><td>2 weeks at 32 ° C g / cm ^ s (cps)</td><td>4 weeks at 32 ° C g / cnrs (cps)</td><td>p^aboutreceipt (% wt)</td><td>2 weeks at 32 ° C (weight%)</td><td>4 weeks at 32 ° C (weight%)</td><td>Content reduction,%</td>

<td> 3,8</td><td> 1,48 (148)</td><td> 3,47 (347)</td><td>half-hearted gelation</td><td> 10,1</td><td> 9,5</td><td> 9,0</td><td> 11%</td>

<td> 2,1</td><td> 0,76 (76)</td><td> 0,84 (84)</td><td> 0,85 (85)</td><td> 10,6</td><td> 9,8</td><td> 9,6</td><td> 9%</td>

[0047] As with hydrochloric acid, pH correction to low pH ensured physical stability.

[0048] An attempt was made to adjust the pH of the PVAm resin with sulfuric acid, but the resin was unusable becoming a non-homogeneous, viscous mass at a pH below about 5.

[0049] Example 3: The sizing parameters for the sizing compositions of the present invention are much better for mixtures obtained by mixing the resin with the sizing agent at the point of addition:

[0050] A sizing composition was prepared as described in Example 1 using polyvinylamine 1, whose pH was adjusted to 2.1. The sizing composition was assessed using a paper machine on a semi-technical scale as described above after conditioning for 1 hour, 5 hours and 24 hours. It was compared with a Hercon 100 sizing agent without a polymer and with a polymer added at the addition site (addition site testing) with the same ratio of the ketene alkyl dimer used in the sizing compositions (12.5% ​​relative to dimer). Sizing was determined using the Hercules sizing test (Tappi T 530 method) and Cobb test (Tappi T 441 method). In the Hercules sizing test, higher values ​​(longer penetration times) indicate an improvement in sizing parameters. In the Cobb test, lower values ​​(lower water absorption) indicate an improvement in sizing parameters. The results are shown in Table 3.

Table 3. Conditioning the sizing compositions of the present invention significantly increases sizing efficiency.

<td></td><td></td><td>HST</td><td>20% FA paint</td><td>COBBA TEST</td><td>WATER</td>

<td></td><td></td><td>5 reps</td><td>80% REFL.</td><td>2 reps</td><td>SOAKING FOR 2 MIN</td>

<td></td><td>dimer</td><td>seconds</td><td></td><td>g / m²</td><td></td>

<td></td><td>Appendix,%</td><td>Average</td><td>Deviation standard</td><td>Average</td><td>Deviation standard</td>

<td>Without PVAm</td><td> 0,100</td><td> 3</td><td></td><td> 321</td><td> 3,54</td>

<td>Without PVAm</td><td> 0,200</td><td> 12</td><td></td><td> 161</td><td> 7,07</td>

<td>Without PVAm</td><td> 0,300</td><td> 39</td><td> 1,48</td><td> 66</td><td> 2,83</td>

<td></td><td></td><td></td><td></td><td></td><td></td>

<td>PVAm added at the addition site</td><td> 0,050</td><td> 2</td><td></td><td> 332</td><td> 3,54</td>

<td>PVAm added at the addition site</td><td> 0,150</td><td> 22</td><td> 1,41</td><td> 74</td><td> 1,41</td>

<td>PVAm added at the addition site</td><td> 0,250</td><td> 165</td><td> 8,00</td><td> 35</td><td> 0,71</td>

<td></td><td></td><td></td><td></td><td></td><td></td>

<td>Example 1: conditioning for 1 hour</td><td> 0,050</td><td> 4</td><td></td><td> 288</td><td> 4,95</td>

<td>Example 1: conditioning for 1 hour</td><td> 0,150</td><td> 60</td><td> 2,77</td><td> 34</td><td> 0,00</td>

<td>Example 1: conditioning for 1 hour</td><td> 0,250</td><td> 276</td><td> 14,30</td><td> 31</td><td> 0,00</td>

<td></td><td></td><td></td><td></td><td></td><td></td>

<td>Example 1: conditioning for 5 hours</td><td> 0,650</td><td> 5</td><td></td><td> 269</td><td> 9,90</td>

<td>Example 1: conditioning for 5 hours</td><td> 0,150</td><td> 83</td><td> 0,58</td><td> 35</td><td> 2,12</td>

<td>Example 1: conditioning for 5 hours</td><td> 0,250</td><td> 379</td><td> 19,60</td><td> 30</td><td> 0,00</td>

<td></td><td></td><td></td><td></td><td></td><td></td>

<td>Example 1: conditioning for 24 hours</td><td> 0,050</td><td> 5</td><td></td><td> 273</td><td> 3,54</td>

<td>Example 1: conditioning for 24 hours</td><td> 0,150</td><td> 84</td><td> 2,30</td><td> 33</td><td> 0,00</td>

<td>Example 1: conditioning for 24 hours</td><td> 0,250</td><td> 383</td><td> 13,15</td><td> 30</td><td> 0,71</td>

[0051] This example confirms the improvement of the sizing parameters of the sizing composition of the present invention. According to Weisgerber's description, adding PVAm to the emulsion

AKD improves sizing parameters; just compare the values ​​"Without PVAm" and "PVAm added at the place of addition". With the sizing compositions of the present invention, it is possible to achieve an even greater level of sizing with the same amounts of alkyl ketene dimer and polymer; just compare the values ​​of "PVAm added at the addition site" with any of the data from Example 1.

[0052] Example 4: A sizing composition was prepared as described in example 1 using polyvinylamine 2, the polyvinylamine pH adjusted to 2.1. This product, referred to as example 4, was compared with example 1 in a semi-technical scale paper machine as described above after conditioning the sizing composition for several days. The results are shown in Table 4.

Table 4. Polyvinylamine with a lower degree of hydrolysis can also be used in the sizing compositions of the present invention.

<td></td><td></td><td>HST</td><td></td><td>COBBA TEST</td><td></td>

<td></td><td></td><td>5 reps</td><td></td><td>2 reps</td><td></td>

<td></td><td></td><td>20% paint FA / 80% Refl</td><td></td><td>2 min / WATER</td><td></td>

<td></td><td>dimer</td><td>seconds</td><td></td><td>g / m²</td><td></td>

<td></td><td>Appendix,%</td><td>Average</td><td>Deviation standard</td><td>Average</td><td>Deviation standard</td>

<td>Without PVAm</td><td> 0,1</td><td> 5</td><td> 0,00</td><td> 257,0</td><td> 5,66</td>

<td>Without PVAm</td><td> 0,2</td><td> 15</td><td> 0,84</td><td> 129,5</td><td> 0,71</td>

<td>Without PVAm</td><td> 0,3</td><td> 49</td><td> 3,29</td><td> 61,5</td><td> 2,12</td>

<td></td><td></td><td></td><td></td><td></td><td></td>

<td>Example 4</td><td> 0,05</td><td> 5</td><td> 0,00</td><td> 198,0</td><td> 8,49</td>

<td>Example 4</td><td> 0,15</td><td> 74</td><td> 4,51</td><td> 37,0</td><td> 2,83</td>

<td>Example 4</td><td> 0,25</td><td> 345</td><td> 11,90</td><td> 29,0</td><td> 1,41</td>

<td></td><td></td><td></td><td></td><td></td><td></td>

<td>Example 1</td><td> 0,05</td><td> 6</td><td> 0,00</td><td> 137,5</td><td> 2,12</td>

<td>Example 1</td><td> 0,15</td><td> 118</td><td> 6,89</td><td> 30,0</td><td> 0,00</td>

<td>Example 1</td><td> 0,25</td><td> 390</td><td> 34,15</td><td> 26,5</td><td> 0,71</td>

[0053] Both polyvinylamines resulted in a significant improvement in sizing, as indicated by both higher HST sizing values ​​and lower Cobb test values.

[0054] Example 5. Variation in the ratio of ketene dimer to polyvinylamine.

[0055] Sizing compositions were prepared according to example 1 by changing the ratio of polyvinylamine to dimer. In all cases, polyvinylamine 1 was used, whose pH was adjusted to 2.1 with hydrochloric acid. The sizing compositions were tested using a paper machine on a semi-technical scale as described above. The results of sizing tests on the resulting cardboard are given in Table 5.

Table 5. Increasing the amount of polyvinylamine resin improves sizing parameters.

<td></td><td></td><td colspan="2">HST</td><td>TEST C.</td><td>Obba</td>

<td></td><td></td><td colspan="2">20% FA paint</td><td colspan="2">Soaking for 2 min</td>

<td></td><td></td><td colspan="2">80% reflectance</td><td colspan="2">water</td>

<td>% PVAm</td><td></td><td colspan="2">seconds</td><td colspan="2">g / m²</td>

<td>relative to dimer</td><td>% dimer</td><td>Average</td><td>Deviation standard</td><td>Average</td><td>Deviation standard</td>

<td> 0</td><td> 0,100</td><td> 8</td><td> 1</td><td> 236</td><td> 4,95</td>

<td></td><td> 0,200</td><td> 39</td><td> 2</td><td> 79</td><td> 3,54</td>

<td></td><td> 0,300</td><td> 133</td><td> 3</td><td> 41</td><td> 0,71</td>

<td> 5</td><td> 0,050</td><td> 10</td><td> 1</td><td> 158</td><td> 39,60</td>

<td></td><td> 0,150</td><td> 128</td><td> 6</td><td> 33</td><td> 1,41</td>

<td></td><td> 0,250</td><td> 831</td><td> 10</td><td> 32</td><td> 1,41</td>

<td> 10</td><td> 0,050</td><td> 7</td><td> 0</td><td> 240</td><td> 2,12</td>

<td></td><td> 0,150</td><td> 152</td><td> 5</td><td> 35</td><td> 2,12</td>

<td></td><td> 0,250</td><td> 966</td><td> 45</td><td> 27</td><td> 0,00</td>

<td> 19</td><td> 0,050</td><td> 7</td><td> 0</td><td> 220</td><td> 2,83</td>

<td></td><td> 0,150</td><td> 172</td><td> 4</td><td> 34</td><td> 1,41</td>

<td></td><td> 0,250</td><td> 1608</td><td> 147</td><td> 31</td><td> 2,83</td>

[0056] These data prove that increasing the polyvinylamine content of the blend results in improved sizing parameters, however, significant increases are observed in the case of relatively low polymer levels.

[0057] Example 6:

[0058] A sizing composition was prepared as described in Example 1 using polyvinylamine 1, whose pH was adjusted to 2.1. The sizing composition was evaluated using an industrial paper machine after conditioning for 1 week. It was compared with a Hercon 118 sizing agent emulsion of an alkyl ketene dimer with a promoter (Hercules Incorporated, Wilmington DE). Sizing was measured using the Cobb test. The results are shown in Table 6. The sizing composition of the present invention met the sizing requirements at an addition level of 24% lower than that of an existing product.

Table 6. Evaluation in industrial conditions confirms the improvement of effectiveness.

<td></td><td>Content of added AKD,%</td><td>2 min, Cobb, g / m², average</td><td>30 min, Cobb, g / m2, average</td><td>Improvement,%</td>

<td colspan="5">Species: white top cover carton No. 42</td>

<td>Hercon 118</td><td> 0,175</td><td> 43</td><td> 107</td><td></td>

<td>Example 6</td><td> 0,133</td><td> 46</td><td> 113</td><td> 24,1</td>

[0059] This example shows that the amount of sizing adhesive used for the material according to the invention is about 24% less than commercially available material, while the correct Cobb test results are still obtained.