US008317974B2

(12) United States Patent (10) Patent No.: US 8,317.974 B2 Duggirala et al. (45) Date of Patent: *Nov. 27, 2012

(54) DEINKING ACELLULOSIC SUBSTRATE (51) Int. Cl. USING MAGNESUM HYDROXDE D2C5/02 (2006.01) 52) U.S. Cl...... 162/8: 162/4; 162/5 (75) Inventors: Prasad Y. Duggirala, Naperville, IL (52) O A O s s (US); Michael J. Murcia, DeKalb, IL (58) Field of Classification Search ...... 162/4-8 (US s s See application file for complete search history. (73) Assignee: Nalco Company, Naperville, IL (US) (56) References Cited (*) Notice: Subject to any disclaimer, the term of this U.S. PATENT DOCUMENTS past list: G adjusted under 35 8,133,351 B2* 3/2012 Duggirala et al...... 162/8 M YW- y yS. * cited by examiner This patent is Subject to a terminal dis claimer. Primary Examiner — Anthony Calandra (21) Appl. No.: 13/366,644 (74) Attorney, Agent, or Firm — Califee, Halter & Griswold LLP (22) Filed: Feb. 6, 2012 (65) Prior Publication Data (57) ABSTRACT US 2012/O135908A1 May 31, 2012 A composition and method for deinking is disclosed. The composition and method contain an activated magnesium Related U.S. Application Data hydroxide or a magnesium hydroxide. (63) Continuation of application No. 12/169,900, filed on Jul. 9, 2008, now Pat. No. 8,133,351. 3 Claims, 2 Drawing Sheets

Witeness

78 FS f4

F.

38 8383-2 $g 38-33 3: d Siksia: 3-3E OA afi: higi 3-3

U.S. Patent Nov. 27, 2012 Sheet 1 of 2 US 8,317.974 B2

is 3. 2.340 8. 88: 1586 49. 493 is 24 it

3: i

FIG RE

SO Brightness

4.32

SR -- -:

FCGRE 2 U.S. Patent Nov. 27, 2012 Sheet 2 of 2 US 8,317.974 B2 23.4.8.878S. $43-33 as gf8:

FGRE 3

Whiteness

8 :hic38. kg 3-32 Ag3-3 aid is: S&c. 8-2 s

FIGRE US 8,317,974 B2 1. 2 DENKINGA CELLULOSC SUBSTRATE The present invention further provides for a method of USING MAGNESUM HYDROXDE removing ink from a cellulosic containing Substance com prising: (a) adding to the Substance a composition compris This application is a continuation application of U.S. ing: (1) magnesium hydroxide, (2) a Suspending agent for patent application Ser. No. 12/169,900, filed Jul.9, 2008, now said magnesium hydroxide, (3) water, and (4) optionally an U.S. Pat. No. 8,133,351. emulsifier; (b) optionally excluding adding caustic soda to the cellulosic containing Substance; and (c) optionally excluding FIELD OF THE INVENTION adding hydrogen peroxide to the cellulosic containing Sub Stance. The invention pertains to compositions and methods for 10 deinking a cellulosic Substrate. BRIEF DESCRIPTION OF THE DRAWINGS BACKGROUND OF THE INVENTION FIG. 1 shows residual ink data after the application of an activated magnesium hydroxide and emulsified TOFA for Efficiently removing ink from secondary fiber without 15 mulation to fiber. impacting fiber quality is one of the major challenges in paper FIG. 2 shows ISO brightness after the application of an recycling. Currently, the most widespread method of remov activated magnesium hydroxide and emulsified TOFA for ing ink from secondary fiber is an alkaline process that uses mulation to fiber. Sodium hydroxide, Sodium silicate, hydrogen peroxide, Sur FIG. 3 shows sheet yellowness after the application of an factants and chelants. The caustic is used to elevate the pH in activated magnesium hydroxide and emulsified TOFA for the repulper causing the fiber to Swell, which assists in ink mulation to fiber. detachment, but also yellows the fiber due to interaction with FIG. 4 shows fiber whiteness after the application of an lignin in mechanical grades, resulting in a brightness loss. activated magnesium hydroxide and emulsified TOFA for Peroxide is added to reduce fiber yellowing, and chelant is mulation to fiber. added to prevent peroxide degradation by metals. Surfactants 25 are used to manage the detached ink and prevent redeposition DETAILED DESCRIPTION OF THE INVENTION onto the fiber. While the conventional method of deinking is effective for A. Definitions ink removal, it has disadvantages. When the cost of the chemicals needed to overcome the unwanted effects of caus 30 "Suspending agent’ means one or more agents that pre tic is considered, the alkaline method is quite expensive. vents precipitation of a stabilized dispersion of colloidal par Aside from the high cost of the chemicals used, handling ticles in solution. caustic can be hazardous, and it is critical to maintain the 'Activated magnesium hydroxide' means a formulation proper balance of caustic, peroxide and silicate to produce that includes magnesium hydroxide plus one or more com fiber with the desired optical properties. Moreover, any ponents that provides additional deinking performance over residual fiber yellowing, or chromophoric generation, that is 35 the magnesium hydroxide alone, e.g. oil added as formulation caused by caustic and cannot be removed with bleaching is with magnesium hydroxide. For example, if the magnesium balanced blue dye to the fiber. While this is effective for hydroxide is mixed with an oil and that oil meets the require achieving a neutral color balance, it reduces ISO brightness, ments of providing additional deinking performance, then the making it difficult to reach brightness targets. In addition, a magnesium hydroxide is an activated magnesium hydroxide. recent study showed that fiber strength and tensile index was 40 “Recycling process' means any process that involves the reduced for secondary fiber deinked under alkaline condi handling of secondary fibers. tions. Finally, the elevated pH in the pulper saponifies adhe “TOFA' means tall oil fatty acid. sives, thereby introducing more Stickies into the papermaking “%' means percent by weight of the composition. system, which cause runnability problems for the paper machine. 45 B. Compositions An improved methodology is therefore desired. As stated above, the present invention provides for a com SUMMARY OF THE INVENTION position comprising: (a) activated magnesium hydroxide; (b) optionally a Suspending agent for said activated magnesium The present invention provides for a composition compris 50 hydroxide; (c) water; (d) optionally an emulsifier; (e) option ing: (a) activated magnesium hydroxide; (b) optionally a sus ally excluding adding caustic Soda; and (f) optionally exclud pending agent for said activated magnesium hydroxide; (c) ing hydrogen peroxide. The present invention also provides water; (d) optionally an emulsifier; (e) optionally excluding for a composition comprising: (a) magnesium hydroxide; (b) caustic soda, and (f) optionally excluding hydrogen peroxide. a suspending agent for said magnesium hydroxide; (c) water; The present invention also provides for a composition (d) optionally an emulsifier; (e) optionally excluding caustic comprising: (a) magnesium hydroxide; (b) a Suspending 55 Soda; and (f) optionally excluding hydrogen peroxide. agent for said magnesium hydroxide; (c) water; (d) optionally In one embodiment, the Suspending agent is a thickening an emulsifier; (e) optionally excluding caustic Soda; and (f) agent. optionally excluding hydrogen peroxide. In another embodiment, the thickening agent is selected The present invention also provides for a method of remov from the group consisting of galactomannans, guar gum, ing ink from a cellulosic containing Substance comprising: (a) 60 locust bean gum, Xanthan gum, para gum, cellulosics; adding to the Substance a composition comprising: (1) acti hydroxypropyl methylcellulose; hydroxypropyl cellulose; vated magnesium hydroxide, (2) water, (3) optionally a sus carrageean; alginates; Sodium alginates; potassium alginates, pending agent for said activated magnesium hydroxide, and ammonium salt alginates; and a combination thereof. (4) optionally an emulsifier; (b) optionally excluding adding In another embodiment, the composition contains from caustic soda to the cellulosic containing Substance; and (c) 65 about 5% to about 70% of said activated magnesium hydrox optionally excluding adding hydrogen peroxide to the cellu ide/magnesium hydroxide, based upon weight of the compo losic containing Substance. sition. US 8,317,974 B2 3 4 In another embodiment, the composition contains about from the resulting deinked fiber. In addition to optical prop 47% of said activated magnesium hydroxide/magnesium erties, an ink speck count measurement is used to evaluate the hydroxide, based upon weight of the composition. efficiency with which the ink is removed. Residual ink can be In another embodiment, the composition contains from expressed in terms of speckS/unit area, percent coverage of about 0.05% to about 20% of said suspending agent, based ink specks on an area, or effective residual ink concentration upon weight of the composition. (ERIC), which is commonly expressed in ppm. In another embodiment, the composition contains about In one embodiment, the cellulosic Substance is located 0.4% of said Suspending agent, based upon weight of the anywhere in a recycling process up through one or more composition. flotation accepts. In another embodiment, the composition comprises an oil. 10 In another embodiment, the emulsifier is added separately In another embodiment, the composition contains from to the cellulosic containing Substance. about 2% to about 55% of said oil based upon the weight of In another embodiment, the Suspending agent is a thicken the composition. ing agent. In another embodiment, the composition contains about In another embodiment, the thickening agent is selected 30% of said oil based upon the weight of the composition. 15 from the group consisting of galactomannans, guar gum, In another embodiment, the oil contains a fatty acid. locust bean gum, Xanthan gum, para gum, cellulosics; In another embodiment, the oil is used to form an oil and water emulsion. hydroxypropyl methylcellulose; hydroxypropyl cellulose; In another embodiment, the composition contains from carrageean; alginates; Sodium alginates; potassium alginates, about 0.5% to about 20% of said emulsifier. ammonium salt alginates; and a combination thereof. In another embodiment, the composition contains about In another embodiment, the composition contains from 3% of said emulsifier. about 5% to about 70% of said activated magnesium hydrox In another embodiment, the emulsifier is a Surfactant. ide/magnesium hydroxide, based upon weight of the compo In another embodiment, the fatty acid contains a tall oil sition. fatty acid. In another embodiment, the composition contains about In another embodiment, the emulsifier is selected from the 25 47% of said activated magnesium hydroxide/magnesium group consisting of Sorbitol derivatives; polysorbate 80; Sor hydroxide, based upon weight of the composition. bitan monolaurate; polysorbate 20; ethoxylated alcohols; In another embodiment, the composition contains from Sodium laureth Sulfate; polyethylene glycol, Sulfate esters; 0.05% to about 20% of said suspending agent, based upon Sodium lauryl Sulfate; and a combination thereof. weight of the composition. In another embodiment, the composition comprises: (a) 30 In another embodiment, the composition contains about activated magnesium hydroxide/magnesium hydroxide; (b) 0.4% of said Suspending agent, based upon weight of the Xanthan gum; (c) tall oil fatty acid; (d) sodium lauryl Sulfate; composition. and (e) water. In another embodiment, the composition further com In a further embodiment, the composition is comprised of prises: an oil. about 47% of said activated magnesium hydroxide/magne 35 In another embodiment, the composition contains from sium hydroxide; about 0.395% xanthan gum; about 30% tall about 2% to about 55% of said oil based upon the weight of oil fatty acid; and about 3% sodium lauryl sulfate. the composition. In another embodiment, the composition excludes caustic In another embodiment, the composition contains about Soda, optionally comprising rosin wherein the content of 30% of said oil based upon the weight of the composition. rosin in the composition is from greater than 0% to about 30% In another embodiment, the composition contains from based upon weight of the fatty acid. 40 about 0.5% to about 20% of said emulsifier. These compositions may be applied in methods of remov In another embodiment, the composition contains about ing ink from a cellulosic containing Substance/substrate. In 3% of said emulsifier. the next section, various embodiments of these applications In another embodiment, the oil contains a fatty acid. are discussed. In another embodiment, the oil is used to form an oil and 45 water emulsion. C. Methods In another embodiment, the emulsifier is a Surfactant. In another embodiment, the fatty acid contains a tall oil As stated above, the present invention provides for a fatty acid. method of removing ink from a cellulosic containing Sub In another embodiment, the emulsifier is selected from the stance comprising: (a) adding to the Substance a composition 50 group consisting of Sorbitol derivatives; polysorbate 80; Sor comprising: (1) activated magnesium hydroxide, (2) water, bitan monolaurate; polysorbate 20; ethoxylated alcohols; (3) optionally a Suspending agent for said activated magne Sodium laureth Sulfate; polyethylene glycol; Sulfate esters; sium hydroxide, and (4) optionally an emulsifier; (b) option Sodium lauryl Sulfate; and a combination thereof. ally excluding adding caustic Soda to the cellulosic contain In another embodiment, the composition excludes caustic ing Substance; and (c) optionally excluding adding hydrogen Soda. peroxide to the cellulosic containing Substance. The present 55 In another embodiment, the composition further comprises invention also provides for a method of removing ink from a rosin, optionally wherein the content of rosin in the compo cellulosic containing Substance comprising: (a) adding to the sition is from greater than 0% to about 30% based upon Substance a composition comprising: (1) magnesium hydrox weight of the fatty acid. ide, (2) a Suspending agent for said magnesium hydroxide, (3) In another embodiment, the method of removing ink from water, and (4) optionally an emulsifier; (b) optionally exclud 60 a cellulosic containing Substance comprises: (a) adding to the ing adding caustic soda to the cellulosic containing Sub Substance a composition comprising: (1) activated magne stance; and (c) optionally excluding adding hydrogen peroX sium hydroxide/magnesium hydroxide, (2) Xanthan gum, (3) ide to the cellulosic containing Substance. tall oil fatty acid, (4) sodium lauryl sulfate, and (5) water; (b) The performance of a deinking process can be measured in optionally excluding the addition of caustic soda to the cel a variety of ways. Typically, optical properties such as bright 65 lulosic containing Substance; and (c) optionally excluding the ness (B), whiteness (L), red/green color balance (a) and yel addition of hydrogen peroxide to the cellulosic containing low/blue color balance (b) are measured on a sheet formed Substance. US 8,317,974 B2 5 6 In a further embodiment, the composition is comprised of Upon complete repulping, the disintegrated secondary about 47% of said activated magnesium hydroxide/magne fiber was diluted and placed into a floation cell where sium hydroxide; about 0.395% xanthan gum; about 30% tall detached ink was separated from the fiber using an agitator oil fatty acid; and about 3% sodium lauryl sulfate. and air bubbles passing from the bottom to the top of the cell, The methodologies of the present invention can be applied 5 collecting dislodged ink particles. This creates a froth that to a paper recycling process, when deinking is desired. carries the ink and was removed from the top of the floatation In one embodiment, the composition is added to a paper cell. Typical floatation temperatures range from 35-60° C. recycling process in at least one of the following locations: a Upon completion of the floatation stage, the deinked fiber was pulper, dilution stage; flotation cell thickening stage; and a collected and residual ink and optical measurements are kneader. made. In another embodiment, the composition is added in a 10 Measurement Methods: pulper of a paper recycling process. For this study, optical properties of deinked fiber were In another embodiment, the composition is added at a measured using a Technidyne Colortouch 2 on handsheets dilution stage of a paper recycling process. prepared according to TAPPI method T218. In the interest of In another embodiment, the composition is added at a reducing effects of sample preparation, ink speck counts were thickening stage of a paper recycling process. 15 performed using a PAPRICAN InkScanner by Op-Test on the In another embodiment, the composition is added in a same sheets used for optical characterization. flotation cell of a paper recycling process. Sample Results: In another embodiment, the composition is added in a As shown in FIG. 1, the residual ink remaining after the kneader of a paper recycling process. deinking process was measured on handsheets made from In another embodiment, the Substance contains one or deinked fiber. The efficacy of the activated magnesium more paper fibers. hydroxide and emulsified TOFA formulation is clear when In another embodiment, the paper fibers are secondary compared to the variations on the formulation and the con fibers in a paper recycling process. ventional caustic deinking benchmark. The following examples are not meant to be limiting. As shown in FIG. 2, the ISO brightness was measured on handsheets made from deinked fiber. The data shows that the Examples 25 disclosed deinking formulation is capable of outperforming the conventional caustic deinking treatment in brightness A formulation for the removal of ink from secondary fiber ga1n. using under reduced alkalinity conditions can best be realized As shown in FIG. 3, the sheet yellowness, as measured on by thickening a sample of deionized (“DI) water with Xan handsheets prepared from deinked fiber, is slightly higher for than gum at 2.0% by weight with gentle stirring. Adding a 30 the disclosed formulation, but is not too high to overshadow 50/50 mixture of polysorbate 80 and polysorbate 20 at 2.5% the benefits of the formulation has for ink removal and the by weight for the combined surfactant to the Xanthan gum other optical properties. enables the emulsification of tall oil fatty acid at 5.15% by As shown in FIG. 4, the fiber whiteness was measured on weight with mixing of the solution. While mixing, magne fiber deinked with the experimental formulations. Similar to sium hydroxide particles with 1 micron particle size were 35 the trend observed in the brightness measurements, the pro added to the emulsion at a concentration of 5.15% by weight. posed invention outperforms the conventional caustic deink To achieve a stable formulation while maintaining a fluid ing treatment. Viscosity capable of being pumped, the overall Solids in the We claim: formulation were in the range of 15%, but can be increased to 1. A method of removing ink from a cellulosic containing higher Solids percentages. 40 Substance comprising: For example, 0.4 g of Xanthan gum was added to 20 ml of (a) blending a composition comprising: (1) magnesium DI water with gentle stirring to assist in dissolving the pow hydroxide, (2) a Suspending agent for said magnesium der. 0.25 g of polysorbate 20 and 0.25 g of polysorbate 80 hydroxide, (3) an emulsifier, (4) water, and (5) tall oil were added to the xanthan gum solution. 1.2 g of TOFA was fatty acid; added and emulsified with gentle stirring, along with 1.2 g of wherein the composition contains from about 5% to magnesium hydroxide, resulting in a stable emulsified slurry 45 about 70% by weight magnesium hydroxide: of activated magnesium hydroxide and TOFA. The prepared (b) adding the composition to the cellulosic containing sample was Suitable to remove ink from 120g of secondary Substance; fiber. (c) optionally excluding the addition of caustic soda to the The deinking treatment can then be added to secondary cellulosic containing Substance; and fiber in the repulping process at a high consistency of fiber 50 (d) optionally excluding the addition of hydrogen peroxide and an elevated temperature (-35-60° C.) where the sheets to the cellulosic containing Substance. were disintegrated into fiber. To assist in producing a sheet 2. The method of claim 1, wherein said cellulosic contain with higher brightness, peroxide was added to the pulper ing Substance is located anywhere in a recycling process up upon the addition of the disclosed formulation. Traditionally, through at least one flotation accept. hydrogen peroxide was added to the pulper in caustic deink 55 3. The method of claim 1, wherein the composition is ing at a ratio of 0.6:1 caustic to hydrogen peroxide. Given that added to a paper recycling process in at least one of the when replacing caustic (Sodium hydroxide) with magnesium following locations: a pulper, dilution stage; flotation cell hydroxide, the replacement ratio is 1.0:0.73 NaOH:Mg thickening stage; and a kneader. (OH), hydrogen peroxide was added at a ratio of 2.28:1.0 hydrogen peroxide to activated magnesium hydroxide. k k k k k