ANTHRAQUINONE COMPOSITIONS AND PREPARATIONS THEREOF CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Patent Application No. 62/357,671, filed July 1, 2016, which is hereby incorporated by reference in its entirety.

Background

[0002] Anthraquinone (AQ) is a solid that is insoluble in water. There is a need to provide not only a stable and homogeneous suspension of anthraquinone to be used in pulping processes to provide pulp having good papermaking quality, but also a pumpable suspension of anthraquinone, especially when the temperatures in or outside a pulping mill are tropical-like (e.g., at least 30°C). In addition, there is a need to use few components or ingredients in the AQ compositions to keep the costs to prepare such compositions as low as possible. A further need is to use a larger mean particle size of AQ in the AQ compositions compared to current particle sizes for ease of handling and safety. Grinding to finer particle sizes is costly, and finely ground AQ has a tendency to adhere to anything it comes into contact with, including those who work with such a material. "Pulping" generally refers to the reduction or break-down of a bulk fiber source material into its component fibers. Wood and other plant materials used to make pulp generally contain three main components (apart from water): cellulose fibers (desired for papermaking), lignin (a three-dimensional polymer that binds the cellulose fibers together) and hemicelluloses (shorter branched carbohydrate polymers). Fiber sources include wood fibers, e.g., soft woods and hard woods and mixtures thereof, and non-wood fibers obtained from agricultural productions, such as without limitation, bagasse, wheat straw, rice straw, corn stover (stalks, leaves and husks), soy residuals, coconut tissues, cotton stalks, palm baskets, kenaf, industrial hemp, seed flax straw, textile flax straw, sisal, hesperaloe, rye grass, and mixtures thereof. Summary of Drawings

[0003] Figure 1 is a block flow diagram showing the preparation of an AQ composition according to an aspect of the disclosure.

[0004] Figure 2 is a visual showing the stability over 1 week of four AQ compositions prepared according to an aspect of the disclosure.

[0005] Figure 3 is a visual showing the stability over 1 week of AQ compositions prepared according to an aspect of the disclosure.

Detailed Description

[0006] A more detailed description of the present disclosure will be rendered by reference to specific embodiments thereof. Other features and advantages of the present disclosure will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating the preferred embodiments of the present disclosure, are given by way of illustration only, since various changes and modifications within the spirit and scope of the present disclosure will become apparent to those skilled in the art from this detailed description.

[0007] One aspect of the present disclosure relates to an AQ composition comprising

AQ having a mean particle size from about 0.1 micron to about 200 microns, a water soluble or water dispersible polysaccharide, and water, wherein the AQ composition is a substantially homogeneous and stable suspension at room temperature in a closed container from about 24 hours to about 1 year. Further, the AQ composition is also pumpable at temperatures from about 10 to 80°C or about 15 to 70°C, such as, for example, about 20 to 60°C, about 22 to 50 °C, about 23 to 40°C, about 25 to 30°C. Further, the AQ composition can optionally comprise one or more metal ions and additive(s).

[0008] Another aspect is an AQ composition comprising AQ having a mean particle size from about 0.1 micron to about 200 microns, a water soluble or water dispersible polysaccharide, one or more metal ions, preferably water soluble, such as calcium salts and magnesium salts, and water, wherein the composition is a substantially homogeneous and stable suspension at room temperature in a closed container from about 24 hours to about 1 year. Further, the AQ composition is also pumpable at temperatures from about 10 to 80°C or about 15 to 70°C, such as, for example, about 20 to 60°C, about 22 to 50 °C, about 23 to 40°C, about 25 to 30°C. Further, the AQ composition can optionally comprise an additive(s).

[0009] Yet another aspect of the disclosure is the use of the AQ composition in pulping processes. Another aspect of the disclosure is paper products made from the pulping process using the AQ compositions disclosed herein.

[00010] As used herein, the term "substantially homogeneous and stable" means the AQ in the "substantially homogeneous and stable" suspension is dispersed evenly and the AQ does not settle during extended storage for at least 24 hours to one year, even at tropical-like temperatures (i.e., at least 30°C). The settling of AQ in the suspension is determined visually by tilting the container containing the composition and observing its flow properties and looking for settling of AQ at the bottom of the container.

[00011] As used herein, a suspension is "pumpable" when it can be pumped using any pumps used for pumping liquids, such as positive displacement pumps, centrifugal pumps, diaphragm pumps, gear pumps, peristaltic pumps, piston pumps, and syringe pumps.

[00012] As used herein, the term "about" means a range of ±10%, ±5% or ±1%.

[00013] As used herein, the term "polysaccharides" refers to polymeric carbohydrate molecules composed of long chains of monosaccharide units bound together by glycosidic linkages and on hydrolysis give the constituent monosaccharides or oligosaccharides.

Polysaccharides range in structure from linear to highly-branched. Examples include storage polysaccharides such as starch and glycogen, and structural polysaccharides such as cellulose, hemicellulose, and chitin. Depending on the molecular weight and structure, polysaccharides can dissolve completely in water (i.e., water soluble) giving a clear solution, or be dispersed as a powder (i.e., dry fine particles) in water (i.e., water dispersible or not necessarily completely dissolved in water). Typically, water-dispersible polysaccharides require agitation to keep them suspended in water in the absence of other compounds, such as dispersants, that promote suspension.

[00014] When used in an AQ composition, the concentration of the polysaccharides in the AQ composition is from about 0.001% to about 10%, from about 0.01% to about 5%, or from about 0.1% to about 1%.

[00015] The mean particle size of AQ in the AQ composition is about 200 microns, 150 microns or less, about 135 microns or less, about 125 microns or less, about 100 microns or less, about 75 microns or less, about 50 microns or less, about 25 microns or less, about 20 microns or less, about 15 microns or less, about 10 microns or less, about 8 microns or less, about 5 microns or less, about 3 microns or less, about 1 micron or less, about 100 microns to about 1 micron, about 75 microns to about 2 microns, about 50 microns to about 3 microns, about 25 microns to about 4 microns, about 20 microns to about 5 microns, about 10 microns to 6 microns.

[00016] The AQ composition can include a concentration of AQ of at least about 40 wt % or at least about 50 wt %. In one aspect, the AQ concentration can range from about 40 wt % to about 70 wt %, from about 40 wt % to about 60 wt %, from about 40 wt % to about 50 wt %, from about 45 wt % to about 55 wt %, from about 50 wt % to about 70 wt %, from about 50 wt % to about 65 wt %, 50 wt % to about 60 wt %, and from about 50 wt % to about 55 wt %. In another aspect, the AQ concentration is about 40 wt %. In another aspect, it is about 50 wt %.

[00017] Metal ions and dispersants may be used in the AQ composition. If used, the metal ions and the dispersants are water soluble. The one or more metal ions may be monovalent, divalent, trivalent, tetravalent, their salts thereof, and mixtures thereof. The divalent metal ion salts include, without limitation, calcium salt(s) and magnesium salt(s), and they may be any water soluble salt, e.g. chlorides, bromides, nitrates.

[00018] If used in an AQ composition, the concentration of the one or more metal ions is from about 0.01 wt % to about 1 wt %. In one aspect, the total weight of the metal ion salts is about 1.2%. In another aspect, the molar ratio of calcium to magnesium in the AQ composition is about 1:1, about 1.1:0.9, or about 0.9:1.1.

[00019] The dispersant may be a cationic dispersant, an anionic dispersant, or a nonionic dispersant. In one aspect, the anionic dispersant is, for example and without limitation, an aromatic sulfonate, such as a naphathalene sulfonate, and preferably a dialkylnaphthalene sulfonate dispersant. Examples of dialkylnaphathalene sulfonate include, without limitation, sodium salts of dialkylnaphthalene sulfonic acid. In one aspect, the dispersant is sodium diisopropylnaphthalene sulfonate, for example Naxan® DIL dispersant, purchased from the Nease Corporation.

[00020] If used in an AQ composition, the concentration of the dispersant in the AQ composition is from about 0.01% to about 5%, from about 0.05% to about 3% or from about 0.1 to about 2%.

[00021] In one aspect, the molar ratio of AQ to the total calcium in the AQ

composition is about 50:1, about 51:1 to about 49:1, or about 55:1 to about 45:1.

[00022] The AQ composition comprising from about 40 wt % to about 50 wt % AQ as disclosed herein has an initial viscosity at 25 °C from about 500 cP to about 50,000 cP, from about 1,000 cP to about 40,000 cP, from about 2,000 cP to about 35,000 cP, from about 2,400 cP to about 31,000 cP, and from about 2,400 cP to about 25,000 cP. In one aspect, the initial viscosity is from about 3,000 cP to about 25,000 cP, and from 3,200 cP to about 19,000 cP. [00023] The AQ composition as disclosed herein remains stable at room temperature in a closed container for at least about 24 hours, at least about 1 week, at least about 1 month, at least about 3 months, or at least about 6 months. In some aspects, the AQ composition is stable up to about a year.

[00024] Another aspect of the present disclosure relates to an AQ composition comprising AQ having a mean particle size of about 200 microns or less, a polysaccharide, one or more metal ions, a dispersant, and water. One aspect is a composition comprising AQ having a mean particle size of about 150 microns or less, a polysaccharide, one or more calcium salts, one or more magnesium salts, a salt of diisopropylnaphthalene sulfonate, and water. In certain embodiments, the mean particle size of AQ in the AQ composition is about 200 microns or less, about 135 microns or less, about 125 microns or less, about 100 microns or less, about 75 microns or less, about 50 microns or less, about 25 microns or less, about 20 microns or less, about 15 microns or less, about 10 microns or less, 200 microns to about 1 micron, about 100 microns to about 1 micron, about 50 microns to about 1 micron, about 25 microns to about 1 micron, about 20 microns to about 1 micron, about 15 microns to about 1 micron, about 10 microns to about 1 micron, about 8 microns to about 1 micron, about 5 microns to about 1 micron, and about 3 microns to about 1 micron. In certain aspects, AQ is added slowly in small portions with agitation to enable rapid dispersion of AQ in the first solution.

[00025] Yet another aspect of the disclosure relates to a method for preparing the AQ composition as disclosed herein, comprising:

a. providing a first solution comprising water and a polysaccharide, either water soluble or water dispersible;

b. adding AQ of mean particle size from 0.1 micron to 200 microns to the first solution with agitation at a speed such that the first solution forms a substantially homogeneous and stable suspension to obtain a second solution of the AQ composition (i.e., a substantially homogenous and stable suspension of the AQ composition). In certain aspects, when the AQ is added to the first solution, it is added slowly in small portions with agitation to enable rapid dispersion of the AQ.

[00026] The metal ion salts (e.g., calcium and magnesium salts), and the dispersant (e.g., a salt of diisopropylnaphthalene sulfonate), may be added separately or together into water to provide the first solution. Alternatively, the metal ion salts, and the dispersant may be provided as individual solutions and then mixed together to provide the first solution. This be done prior to, or after, adding the polysaccharide.

[00027] In one aspect, the AQ composition is prepared according to the flow chart shown in Figure 1, comprising the following steps:

a. adding water into a tank equipped with an agitator;

b. adding polysaccharide (e.g., scleroglucan, xanthan gum, methylcellulose, guar gum) into the water, and stirring until the polysaccharide dissolves or is dispersed well; c. optionally, adding metal ion salt(s) into the polysaccharide solution prepared in step b., and stirring until all salt(s) dissolve, wherein the metal ion salt(s) may be added together or separately;

d. optionally, adding a dispersant (e.g., a dialkylnaphathalene sulfonate, such as sodium diisopropylnaphthalene sulfonate) into the solution prepared in step c, and stirring until the dispersant dissolves;

e. optionally, adding other additives (e.g., a viscosifier, an emulsifier, a surfactant, an inert material) into the solution in step d., and stirring until the additive dissolves;

f . adding AQ having mean particle size from 0.1 micron to 200 microns into the solution prepared in step (e) slowly and in small portions with agitation to provide a substantially homogeneous AQ composition; and g. optionally, adding a dye or colorant into the substantially homogeneous AQ composition of step f. to provide a substantially homogeneous AQ composition with dye or colorant.

[00028] The above steps b., c, d., e., and g., can be added to the water in any order, and preferably AQ is added in the final step to avoid the formation of clumps. Other compounds that can be used in a pulping process can also be added to the substantially homogeneous AQ composition.

Examples

Materials:

AQ, xanthan gum, guar gum, scleroglucan, methylcellulose, NAXAN-DIL dispersant and CaC and MgCk.ethO were purchased from commercially available sources.

Example 1. Preparation and Testing of AQ compositions at Room Temperature

[00029] AQ compositions having formulations listed in Tables 1-4 were prepared according to the block flow diagram in Figure 1, and the following procedure:

1. A beaker containing the desired amount of water was placed beneath a table top mixer (Model IKA RW20DZM). Any table top mixer that enables the dispersion of AQ may be used.

2. The water-soluble or water-dispersible polysaccharide was added to the water and stirred for about 15 minutes at an appropriate speed until all of the polysaccharide completely dissolved or dispersed uniformly. Clumps of undispersed polysaccharide were avoided. If clumps formed, the solution was agitated longer.

3. Magnesium chloride was added to solution followed by calcium chloride. The mixture was stirred for 5 to 10 minutes at an appropriate speed until both salts dissolved completely. 4. Optionally, other components may be added at this stage, with continued stirring for 5 to 10 minutes at an appropriate speed after each component was added, making sure the components dissolved completely or were dispersed uniformly.

5. The AQ powder was then added in small portions with agitation to provide a dispersed suspension, and stirred for another 10 to 15 minutes at an appropriate speed to ensure the AQ was well-dispersed. The dispersion obtained was visually homogeneous.

Table 1 : AO Composition Formulation with Scleroglucan (wt %)

Table 2: AO Composition Formulation with Xanthan Gum (wt %)

5X used 3 micron AQ

Table 3: AO Composition Formulation with Methylcellulose (wt %)

Table 4: AO Composition Formulation with Guar Gum (wt %)

[00030] The concentration of the AQ in Table 1 through Table 4 varied from either 40 wt % or 50 wt % (i.e., a range of from about 40 wt % to about 50 wt %) and the

polysaccharide ranging from 0.1 wt % to about 0.25 wt %. In each of Tables 1-4, metal ion salts were used for a total weight of 1.2%.

Sample Preparation:

[00031] After mixing, samples of suspensions of the different AQ compositions were slowly poured into glass vials. The headspace above the surface of the sample remained clear. The vial was capped tightly. The viscosity of the samples was taken soon after preparation. After 7 days, the phase stability and pourability of the formulations was observed visually, and the viscosities measured again.

[00032] AQ with a mean particle size of 10 microns was used in all the AQ composition formulations except in the xanthan gum formulation 5X for which AQ of particle size 3 microns was used.

[00033] The calcium chloride and magnesium chloride used in the formulation can be anhydrous or hydrates. The amount of water used in the formulation is adjusted accordingly.

[00034] The viscosity of each formulation at room temperature was measured on a Brookfield Viscometer, Model RBDV III plus, with a #5 Spindle at 5 rpm. The viscosity was measured when the formulations were initially prepared (i.e., initial viscosity), and after the vials sat at room temperature for 7 days. The results are shown in Table 5. [00035] The pourability of these formulations at room temperature was tested by tilting the containers holding these formulations sideways and determining if the formulations flowed or did not flow. The results are shown in Table 5.

Table 5: Viscosity and Pourability of AO Composition Formulations at Room Temperature

NA = Not tested

[00036] The formulations prepared with scleroglucan and methylcellulose were not stable as syneresis was observed after 7 days. The viscosities of formulations prepared with xanthan gum decreased after 7 days and were stable, as observed by their pourability, except formulation 5X. Similarly, the formulation prepared with guar gum was stable, along with a reduction in viscosity.

[00037] Phase separation was observed by pouring formulations, as soon as they were prepared, into glass vials and observing them visually over several days. Figures 2 and 3 are visuals showing such phase separation or lack of phase separation. As discussed above, the formulations prepared with scleroglucan and methylcellulose exhibited syneresis after 7 days. The xanthan gum formulation 5X also exhibited syneresis after 7 days.

[00038] Xanthan gum IX, 2X, 3X, and 4X showed the best results compared to the other polysaccharides tested. Example 2. Preparation and Testing of AQ Compositions at 50°C

[00039] The AQ composition formulations in Tables 1-4 were prepared and placed in an oven at 50°C. Two additional AQ composition formulations were prepared as controls, one containing only water and AQ, and the other water, AQ and Mg/Ca salts. Table 6 shows the stability and pourability of the samples that were observed after 1 week.

Table 6: Stability and Pourability of AQ Composition Formulations at 50°C

[00040] As observed in Table 6, formulations without a polysaccharide were not pourable at all. There was no improvement in the formulations that contained scleroglucan and methylcellulose after heating at 50°C, compared to their behavior at room temperature. The formulation containing guar gum was stable, but became thicker, thus affecting its pourability. Doubling the amount of xanthan gum from 0.1 to 0.2 wt % (comparing IX and 2X) increased the viscosity significantly and decreased its pourability. A dispersant, in this case NAXAN DIL dispersant, is not necessary component as the 3X showed better results than 4X. Xanthan gum IX, 2X, 3X, and 4X at 50°C showed the best results compared to the other polysaccharides tested. In addition, xanthan gum performed similarly at room temperature and at 50°C.