OFFICE WASTEPAPER DEINKING PROCESS

Abstract: This invention related to a process for the deinking of office wastepaper stocks which comprises: a) converting the wastepaper to a pulp, b) contacting the pulp with an aqueous medium of alkaline pH containing between 0.05 and 2 percent by weight, calculated on a dry weight basis of the pulp, of a deinking agent comprising a first component comprising at least one ethylene oxide adduct of a detergent-range alcohol having in the range of from 8 to 20 carbon atoms and an average of from 3 to 20 oxyethylene units per molecule of alcohol, a second component selected from the group consisting of one or more detergent-range olefins having from 8 to 22 carbon atoms, one or more saturated hydrocarbons having from 8 to 20 carbon atoms, and mixtures thereof and optionally a third component comprising a detergent-range alcohol having from 8 to 20 carbon atoms, and c) treating the resulting pulp-containing medium by washing or flotation to remove suspended ink therefrom.

Description: OFFICE WASTEPAPER DEINKING PROCESS This invention relates to a process for the removal of ink from printed office wastepaper in the course of reclaiming the fiber content of the waste for reuse in the manufacture of new paper. More particularly, the invention relates to a process for the deinking of office wastepaper containing xerographically printed paper or paper printed using a laser printer. Wastepaper has long served as a source of the raw fiber materials used in papermaking. Traditionally, fiber from wastepaper was utilized only in the production of low grade paper and paperboard products. Today, however, greater utilization of reclaimed fiber has provided incentive for taking steps to upgrade the reclaimed product. These steps include treatment to effectively remove ink from waste fibers in order to permit their use in the manufacture of newsprint and high quality papers. Increasing amounts of office waste paper are becoming available. Because of the high quality cellulose fiber in office waste paper, efficient ink removal is particularly desirable since excellent quality, high value products can be prepared from this deinked pulp. In the course of the conventional paper reclamation process of interest, deinking procedures include steps for converting the wastepaper to pulp and contacting the pulp with an alkaline aqueous deinking medium containing a chemical deinking agent. The physical pulping and the alkalinity of the aqueous medium cause the partial detachment of ink from the cellulose paper fibers and the deinking agent completes this removal and produces an aqueous suspension and/or dispersion of the ink particles thus detached from the paper cellulose fibers. The _ 4 _ adduct of a detergent-range alcohol having in the range of from 8 to 20 carbon atoms and an average of from 3 to 20 oxyethylene units per molecule of alcohol, and a second component selected from the group consisting of one or more detergent-range olefins, one or more saturated hydrocarbons and mixtures thereof, and c) treating the resulting pulp-containing medium by washing or flotation to remove suspended ink therefrom. The present invention is generally applicable to the deinking of the office wastepaper stocks, in particular those comprising xerographically printed, laser printed and/or ledger printed wastepaper, and also to practices and procedures conventionally employed for their processing. Generally, any such process comprises three principal steps: the first, a step to reduce the wastepaper feed to pulp, the second, a contact between the pulp and an alkaline aqueous medium containing the deinking agent to produce a suspension or dispersion of the ink, and, the third, a treatment of the resulting pulp containing medium to remove suspended or dispersed ink particles therefrom. The first two steps of the process, however, may be combined. The present invention centers upon the composition and performance of the deinking agent . For purposes of the invention, the deinking agent has at least two components, with the first component being an ethoxylated detergent-range alcohol and the second component being selected from the group consisting of one or more detergent-range olefins, one or more saturated hydrocarbons and mixtures thereof . The components are typically blended together using conventional means prior to use in a deinking process. The first component of the deinking agent is one or more oxyethylene adducts (or ethoxylates) of an aqueous medium containing a surfactant as a deinking agent. For example, it is known from U.S. Patent No. 4,561,933, that xerographically printed wastepaper can be deinked using a mixture of one or more C5 to C20 alkanols and nonionic surfactant. It is also known in the paper deinking art (for example, U.S. Patent No. 4,162,186) to employ chemical agents which are ethylene oxide adducts ("ethoxylates") of detergent-range alcohols or alkyl-substituted phenols containing an average of about 7 to about 15 oxyethylene units per molecule of alcohol. It is further known from U.S. Patent No. 4,518,459 to use surfactants for deinking which are hydroxy-terminated or benzyl ether-terminated ethylene oxide-propylene oxide adducts (ethoxypro- poxylates) of high molecular weight or long chain alcohols. It has now been found that a combination of one or more ethoxylated detergent-range alcohols and one or more detergent-range olefins and/or saturated hydrocarbons is very usefully applied as a deinking agent in process for the deinking of office wastepaper. Processes applying this deinking agent are found to offer a high level of performance from the standpoint of the overall brightness and low level of residual visible ink particle of papers prepared from the deinked pulp. In addition, the invention provides for low foaming and high bio- degradability without adverse influence upon deinking performance and reclaimed paper product brightness. The invention therefore relates to a process for the deinking of office wastepaper stocks which comprises: a) converting the wastepaper to a pulp, b) contacting the pulp with an aqueous medium of alkaline pH containing between 0.05 and 2.0 percent by weight, calculated on a dry weight basis of the pulp, of a deinking agent comprising a first component comprising at least one ethylene oxide registered trademark of product manufactured and sold by Shell Chemical Company) , the C^ _ to C15 alcohol blends available as NEODOL 45 Alcohol, the C 12 to C_ _ alcohol blends available as Tergitol 24L (a registered trademark of product manufactured and sold by Union Carbide Corporation) , and the C^2 to c i3 alcohol blends available, for example, as NEODOL 23 Alcohol (Shell) . Suitable alcohol ethoxylates can be prepared by adding to the alcohol or mixture of alcohols to be ethoxylated a calculated amount, e.g., from 0.1 to 0.6, preferably from 0.1 to 0.4 percent by weight, based on total alcohol, of a strong base, typically an alkali metal or alkaline earth metal hydroxide such as sodium hydroxide or potassium hydroxide, which serves as a catalyst for ethoxylation. The resulting mixture is dried, as by vapour phase removal of any water present, and an amount of ethylene oxide calculated to provide the desired number of moles of ethylene oxide per mole of alcohol is then introduced and the alcohol ethoxylate is allowed to react until the ethylene oxide is consumed, the course of the reaction being followed by the decrease in reactor pressure. Preferred alcohol ethoxylate components for use in the deinking agents in the present invention include ethoxylated fatty alcohols, preferably linear primary alcohols with Cg to C20. preferably C12 to Cι_ alkyl groups, and an average of from 3 to 20, more preferably in the range of from 3 to 13 , and most preferably in the range of from 3 to 7 moles of ethylene oxide per mole of alcohol. A particularly preferred class of alcohol ethoxylates is represented by the condensation product of a fatty alcohol having from 12 to 15 carbon atoms and from 3 to 13 moles of ethylene oxide per mole of fatty alcohol. Suitable species of this class of ethoxylates include: the condensation product of C]_2 _C 15 oxo-alcohols and detergent-range alcohols having from 3 to 20 oxyethylene units per molecule of alcohol . Such alcohol ethoxylates are represented by the formula R-0- (CH 2 -CH 2 0) n -H (I) wherein R is a straight-chain or branched-chain alkyl group having in the range of from 8 to 20 carbon atoms, preferably from 12 to 18 carbon atoms, or an alkylaryl group having an alkyl moiety having from 8 to 12 carbon atoms and n represents the average number of oxyethylene groups per molecule and is a number in the range of from 3 to 20, preferably in the range of from 3 to 13, and more preferably in the range of from 3 to 7. The alkyl group can have a carbon chain which is straight or branched. Preferably, about 80 percent of the R groups in the alcohol ethoxylates utilized in the instant invention are straight-chain. It is understood that R can be substituted with any substituent which is inert such as, for example, halogen groups. Ethoxylates within this class are conventionally prepared by the addition of ethylene oxide to the corresponding alcohol (ROH) in the presence of a catalyst. The alcohol ethoxylate component of the deinking agent in the instant invention is preferably derived by ethoxylation of primary or secondary, straight-chain or branched alcohols. The most common ethoxylates in this class and the ones which are particularly useful in this invention are the primary alcohol ethoxylates, i.e., compounds of formula I in which R is an alkyl group and the -O- (CH2-CH2O) n -H ether substituent is bound to a primary carbon of the alkyl group. Alcohols which are suitable for ethoxylation to form the alcohol ethoxylate component of the deinking agent of the instant invention include coconut fatty alcohols, tallow fatty alcohols, and the commercially available synthetic long-chain fatty alcohol blends, e.g., the Cτ_2 to C]_5 alcohol blends available as NEODOL 25 Alcohol (a - 8 - suitable linear olefins from ethylene are described in U.S. Patent Nos. 3,676,523, 3,686,351, 3,737,475, 3,825,615 and 4,020,121. While most of such olefin products are comprised largely of alpha-olefins, higher linear internal olefins are also commercially produced, for example, by the chlorination-dehydrochlorination of paraffins, by paraffin dehydrogenation, and by iso erization of alpha-olefins. Linear internal olefin products in the Cβ to C22 range are marketed by Shell Chemical Company and by Liquichemica Company. These commercial products, whether predominantly internal or alpha-olefins typically contain about 70 percent by weight or more, most often about 80 percent by weight or more, linear mono-olefins in a specified carbon number range (e.g., C 10 to C X 2, C X1 to C 15 , C 1 to Cτ_3, C 15 to Cig, etc.) , the remainder of the product being olefin of other carbon number or carbon structure, diolefins, paraffins, aromatics, and other impurities resulting from the synthesis process. Olefins in the C±2 to C^g range are considered most preferred for use as the olefin component in the deinking agent in the present invention. Saturated hydrocarbons suitable for use as a second component in the deinking agent generally contain from 8 to 20 carbon atoms, and preferably from 12 to 16 carbon atoms. Examples of suitable saturated hydrocarbons include decane, dodecane, tetradecane, hexadecane, octadecane and the like, and mixtures thereof. Other deinking agents may be present as a third component in addition to the alcohol ethoxylate and olefin and/or saturated hydrocarbon deinking agent, such as, for example, alcohols, particularly detergent-range alcohols having 8 to 20 carbon atoms, propoxyethoxylates, glycols, fatty acids, fatty acid propoxyethoxylates and the like. Particularly good results have been obtained with glycols, such as, for example, hexylene glycol. 3 moles of ethylene oxide; the condensation product of narrow cut C 1 4-C15 oxo-alcohols and 7 moles of ethylene oxide per mole of fatty (oxo) alcohol; and the condensation of a narrow cut _2 ~ ~13 fatty (oxo) alcohol and 6.5 moles of ethylene oxide per mole of fatty alcohol. The fatty oxo-alcohols, while primarily linear, can have, depending upon the processing conditions and raw material olefins, a certain degree of branching. The second component of the deinking agent is selected from the group consisting of one or more detergent-range olefins, one or more saturated hydrocarbons and mixtures thereof. The ratio of the first component to the second component is typically in the range of 10:1 to 1:1, preferably from 10:1 to 3:1, and more preferably from 9:1 to 3:1. Olefins which are suitable for use as the second component in the deinking agents in the present invention are detergent-range olefins. These olefins can be alpha olefins or internal olefins and they may be linear or branched, but are preferably linear or lightly branched. Single cut olefins or mixtures of olefins may also be used. In a particularly preferred embodiment, the olefin is an alpha olefin containing from 12 to 18 carbon atoms. Preferred olefins for use in the second component of the deinking agent are, for practical reasons of availability, the commercial olefin products in the Cg to C22 range. While commercial production of such olefins may be carried out by the cracking of paraffin wax, commercial production is more commonly accomplished by the oligomerization of ethylene using procedures well known in the art. The resulting oligomerization products are substantially of linear structure. Commercial olefin products manufactured by ethylene oligomerization are marketed in the United States by Chevron Corporation and Albermarle, and by Shell Chemical Company under the trademark NEODENE. Specific procedures for preparing - 10 - selected from the group consisting of a detergent-range olefin, a Cg to C20 saturated hydrocarbon and mixtures thereof, and optionally, a detergent-range alcohol component, to wastepaper which is necessarily in the form of a pulp, that is, to wastepaper which has first been substantially reduced to the individual fibers. Pulping is suitably conducted using any of the various conventional processes and equipment designed for this purpose. Most conveniently, the wastepaper process feedstock is treated in a device known as a "hydrapulper" , which produces a slurry of the fibers in water having a pH of 8 to 12. After the pulping step, the resulting fibers are contacted in an aqueous medium with the deinking agent. This contacting step may suitably be carried out in the pulping equipment, for example, by simply adding deinking agent and caustic to the aqueous slurry of the hydra¬ pulper. This may be done either before or after addition of the wastepaper to the hydrapulper. Alternatively, the contact may be carried out using separate processing equipment such as for example, kneaders and dispergers, which provides for agitation of the aqueous pulp slurry. For the contact step, the solids content of the pulp is present in a quantity typically between 0.5 and 30.0 percent by weight, calculated as the dry weight of the wastepaper feed relative to total weight of the slurry formed. In a preferred embodiment, the slurry contains between 5 and 20 percent by weight paper fiber. The amount of deinking agent present in the slurry is suitably between 0.05 and 2.0 percent by weight, calculated basis dry fiber weight. In a preferred embodiment, the quantity of deinking agent utilized is between 0.1 and 1.0 percent by weight, with between 0.2 and 0.5 percent by weight being particularly preferred. During contact between the pulp fiber and the deinking agent, it is preferable that the aqueous contact However, detergen -range alcohols are preferred as third component . The optional third component of the deinking agent of the present invention comprises one or more detergent-range alcohols having from 8 to 20 carbon atoms, preferably from 8 to 15 carbon atoms, and more preferably from 9 to 11 carbon atoms. Preferably, the alcohols have a carbon structure which is linear (straight chain) or only moderately branched. Predominantly linear alcohols are preferred for reasons relating to biodegradability in process effluents rather than to deinking performance. Similarly, primary alcohols are preferred, although the invention may be suitably practiced using secondary or tertiary alcohols. Alcohols which are suitable as a third component in the deinking agent in the instant invention include coconut fatty alcohols, stearyl fatty alcohols, tallow fatty alcohols, and the commercially available synthetic long-chain fatty alcohol blends, e.g., the C]_2 to C15 alcohol blends available as NEODOL 25 Alcohol (a registered trademark of product manufactured and sold by Shell Chemical Company) , the Cg to C ] _ι_ alcohol blends available as NEODOL 91 Alcohol, the C14 to C15 alcohol blends available as NEODOL 45 Alcohol, the Cχ2 o C 14 alcohol blends available as Tergitol 24L (a registered trademark of product manufactured and sold by Union Carbide Corporation) , and the Cχ2 to C13 alcohol blends available, for example, as NEODOL 23 Alcohol (Shell) . In the present invention, the ratio of the first component (alcohol ethoxylate) to the second component (olefin) to the third component of the deinking agent is typically in the range of from 10:1:1 to 2:1:1, preferably in the range of from 8:1:1 to 7:3:3, most preferably 7.5:1:1.5. The invention applies the deinking agent comprising a detergent-range alcohol ethoxylate component, a component - 12 - 15 minutes to one hour, and more preferred that the contact time be in the range of from 20 to 50 minutes. Following the contact step between the pulp and the aqueous medium containing the deinking agent, the mixture is treated for separation between the pulp fibers and the ink particles which are both dispersed, or suspended, in the medium. Separation of one or the other from the medium is suitably carried out by techniques commonly applied in conventional deinking practices, including those treatments known in the art as washing and flotation. In washing, the ink particles are rinsed from the pulp by contact with a flow of water, usually a countercurrent flow relative to the pulp. Among the devices commercially used for washing and suitable for use in the practice of the present invention are the sidehill screen, the gravity decker or drum washer, the inclined screw extractor, the screw press, and the twin wire press. Centrifugal cleaners of various designs may also be used to separate the ink from the pulp. Flotation methods of ink isolation generally involve bubbling a stream of air or another gas through the pulp. The air bubbles rise to the surface and carry the ink particles with them thereby generating foam which can be separated. It will be understood that in addition to pulping, contact and ink removal steps described herein, the invention may be practiced using other process steps as are employed in wastepaper reclamation operations in general and office wastepaper in particular. The invention will be illustrated below by the following examples. Example 1 This example illustrates the deinking of xerographically printed paper carried out using a deinking agent comprising a 3:1 ratio of NEODOL 25-3 (a mixture of Cι_2 to C15 predominantly linear and primary alcohols, i.e., about 28 %wt . C 12 , 30 %wt. C 13 , 22 %wt . medium be maintained at alkaline pH. A pH value greater than 7 is preferred, a pH between 7 and 13 is more preferred, and a pH between 8 and 10 is generally most preferred. The alkalinity is generally maintained by the addition of base such as, for example, caustic or sodium silicate, to the aqueous contact medium. Typically, the amount of base added to the contact medium is in the range of from 1 to 4 percent by weight calculated basis the dry weight of the pulp fiber. In addition to water, pulp, base and deinking agent, the contact slurry may further contain other substances conventionally employed in deinking processes such as, for example, brighteners, solvents, antifoam agents, water softeners and the like. These substances, if present, along with additional deinking agents, if present, may be added to the pulper when the deinking agent comprising a detergent-range alcohol ethoxylate component and a detergent-range olefin and/or a saturated hydrocarbon component, is added or they may be added to separate process equipment. However, neither the use of these substances nor the use of additional deinking agents is necessary. Processing of the pulp slurry during contact with the deinking agent is preferably carried out at elevated temperatures, particularly temperatures in the range of from 30 °C to 95 °C. The invention has been found to be particularly effective at a temperature in the range of from 35 °C to 70 °C, while a temperature in the range of from 40 °C to 60 °C is considered especially preferred. The contact time for the wastepaper pulp and the aqueous deinking medium is not critical for purposes of this invention. However, a contact time of greater than 10 minutes is preferred from the standpoint of deinking performance. For purposes of process efficiency, it is preferred that the contact time be in the range of from - 14 - The pulp slurry was added to the container and diluted to a total volume of 2.5 litres using additional 40°-45 °C tap water. Pulp slurry consistency was about 0.8% by weight. This mixture was stirred for 10 minutes at 900 revolutions per minute while slurry foam was skimmed off and collected. The slurry was decanted from the flotation cell without pulp loss. Paper Making. Deinking process performance was measured by making paper from the deinked pulp and analyzing the paper for brightness and visible ink particles. The standard of comparison for determining the percent of visible ink particle removed was the paper sheets made immediately after pulping. The pulp was divided into four portions so that at least three, and preferably four, handsheets each weighing 2-4 grams could be made. Each portion of pulp was dispensed in 40°-45 °C tap water and poured into a Buchner funnel fitted with Whatman Number 40 filter paper and placed in a vacuum flask connected to a house vacuum line. In the Buchner funnel, pulp was deposited forming a wet sheet, through which water drained rapidly. The sheet thus formed was covered with two pieces of thick dry filter paper (two above and two below) and the several layers then squeezed by rolling with a 13.6 kg rolling pin. The layers were next removed from the apparatus and the prepared sheet separated from the filter papers. Finally, the prepared sheet was placed between four thick filter papers (two above and two below) , pressed with a force of 445 kPa, and dried between fresh thick filter papers at room temperature in the dark for about 24 hours. The papers ("Buchner funnel pads") thus prepared were analyzed for brightness. Brightness measurements were made on the basis of percent light reflection from the sheet, using a standardized Technidyne Technibrite ERIC C ] _4 and 20 %wt . Cι_ , containing an average of 3 oxy¬ ethylene units per molecule) to NEODENE 10 (at least 97% C ] _o and at least 96% normal alpha olefin) . NEODOL and NEODENE are trademarks of Shell Oil Company. To test the performance of the invention, the following procedures were carried out for the deinking of xerographically printed wastepaper. Sample Preparation. Xerographically printed paper was aged at least three days and then shredded by hand and mixed well. Multiple copies of the same printed page were used. Hydrapulping and Deinking. Deionized water was heated to 40-45 °C. Sodium hydroxide pentahydrate was added to adjust the pH to about 9. To this was added 0.5 grams of the deinking agent (0.25% weight calculated on the weight of the pulp) . This was added as a 1% solution or dispersion in deionized water. A slurry of about 5% consistency was prepared by adding 20 grams of shredded xerographically printed paper. This slurry was mixed for 30 minutes in a Hamilton-Beach mixer on the high speed stir setting. This slurry was separated into two equal portions. One portion of the slurry was made into sheets using Buchner funnel filtration. The other portion was subjected to flotation. Flotation. Deionized water was heated to 40°-45 °C and 2 litres placed in a Denver Flotation Machine. This unit consists of a stir motor, an impeller shaft and stirrer blade and a container for the pulp slurry. As the slurry is stirred, air is drawn down the hollow stirrer shaft and exits at the stirrer blades through small holes. The air bubbles created in the fashion rise through the pulp slurry taking ink particles with them. The froth at the top of the container is removed to separate the ink particles from the pulp slurry. - 16 - NEODOL 25-3 (a mixture of C 12 to C 15 predominantly linear and primary alcohols, i.e., about 28 %wt . C 12 , 30 %wt . C;L3, 22 %wt . C 14 and 20 %wt . C^, containing an average of 3 oxyethylene units per molecule) to NEODENE 16 (at least 92% C g and at least 94% normal alpha olefin) . The results are presented in Table I . Example 5 The procedures of Example 1 were repeated with the exception that the deinking agent used was a 3:1 ratio of NEODOL 25-3 (a mixture of C 12 to C 15 predominantly linear and primary alcohols, i.e., about 28 %wt. C 72 » 30 %wt. C13, 22 %wt . C]_4 and 20 %wt . C15, containing an average of 3 oxyethylene units per molecule) to NEODENE 2024 (at least 40% C 2 0- at least 38% C 2 2. at least 8% C 2 4, and at least 90% normal alpha olefin) . The results are presented in Table I . Example 6 The procedures of Example 1 were repeated with the exception that the deinking agent used was a 3:1 ratio of NEODOL 25-3 (a mixture of C 12 to C 15 predominantly linear and primary alcohols, i.e., about 28 %wt . C12, 30 %wt. C13, 22 %wt . C]_4 and 20 %wt.'Cτ_5, containing an average of 3 oxyethylene units per molecule) to NEODENE 1518 internal olefin (at least 19% C1 . 5, 27% C 16 , 30% C 17 at least 21% C]_g, and at least 14% carbon chain branching) . The results are presented in Table I . Comparative Example A The procedures of Example 1 were repeated with the exception that no deinking agent was used. The results are presented in Table I. Comparative Example B The procedures of Example 1 were repeated with the exception that the deinking agent used was a 3:1 ratio of NEODOL 25-3 (a mixture of Cη_2 to C_5 predominantly linear and primary alcohols, i.e., about 28 %wt . C^2 ■ 30 %wt. C13, 22 %wt . C14 and 20 %wt . 0^5, containing an average 950 meter (Technidyne Technibrite is a Trademark) . Eight measurements were made for each sheet, one at the center of each of four quadrants on both sides, and the eight values averaged for the sheet. Normally, the eight separate measurements varied over a range of no more than 1%. Reported brightness readings were the average of the brightness results for at least three similarly processed sheets. The hand sheets were inspected for visible ink particles using an image analysis method. Images of the entire sheet were directly input into an Applied Vision Systems ASA 2000 Image Analyzer. The visible ink particle count (in parts per million) was determined for particles larger in area than 0.02 square millimetres. The results of these tests are presented in Table I. Example 2 The procedures of Example 1 were repeated with the exception that the deinking agent used was a 3:1 ratio of NEODOL 25-3 (a mixture of C12 to C^ predominantly linear and primary alcohols, i.e., about 28 %wt . C^2' 30 ^ t • C13, 22 %wt . C 14 and 20 %wt . C- ζ , containing an average of 3 oxyethylene units per molecule) to NEODENE 14 (at least 95% C14 and at least 94% normal alpha olefin) . The results are presented in Table I . Example 3 The procedures of Example 1 were repeated with the exception that the deinking agent used was a 9:1 ratio of NEODOL 25-3 (a mixture of C12 to C15 predominantly linear and primary alcohols, i.e., about 28 %wt. C12, 30 %wt . Cι_3 , 22 %wt. C]_4 and 20 %wt . C15, containing an average of 3 oxyethylene units per molecule) to NEODENE 14 (at least 92% C14 and at least 94% normal alpha olefin) . The results are presented in Table I. Example 4 The procedures of Example 1 were repeated with the exception that the deinking agent used was a 3:1 ratio of - 18 - Example IQ The procedures of Example 1 were repeated with the exception that the deinking agent used was a 4:4:2 ratio of NEODOL 45-7 (a mixture of C14 to C 15 predominantly linear and primary alcohols, i.e., about 52 %wt . C 14 and 48 %wt . - _ , containing an average of 7 oxyethylene units per molecule) to NEODENE 14 (at least 95% C 1 and at least 94% normal alpha olefin) to hexylene glycol. The results are presented in Table I . Comparative Example D The procedures of Example 10 were repeated with the exception that the deinking agent contained a NEODOL 45 alcohol component in place of the NEODENE 14 olefin component . The results are presented in Table I. of 3 oxyethylene units per molecule) to NEODOL 25 (a mixture of C 12 to C15 predominantly linear and primary alcohols, i.e., about 28 %wt. C 1 , 30 %wt. Cη^, 22 %wt . C 14 and 20 %wt . C 15 ) . The results are presented in Table I . Comparative Example C The procedures of Example 1 were repeated with the exception that the deinking agent used contained a NEODOL 1 (a mixture of C^Q predominantly linear and primary alcohol) alcohol component in place of the alcohol ethoxylate component . The results are presented in Table I . Example 7 The procedures of Example 1 were repeated with the exception that the deinking agent used was a 3:1 ratio of NEODOL 45-7 (a mixture of C^ _ to C15 predominantly linear and primary alcohols, i.e., about 52 %wt . C_4 and 48 %wt. C15, containing an average of 7 oxyethylene units per molecule) to NEODENE 16 (at least 92% C 16 and at least 94% normal alpha olefin) . The results are presented in Table I. Example 8 The procedures of Example 7 were repeated with the exception that the deinking agent contained a saturated hydrocarbon component, tetradecane, in place of the NEODENE 16 olefin component. The results are presented in Table I . Example 9 The procedures of Example 1 were repeated with the exception that the deinking agent used was a 6:2:2 ratio of NEODOL 45-7 (a mixture of Cχ4 to C ] _5 predominantly linear and primary alcohols, i.e., about 52 %wt. C 14 and 48 %wt . C15, containing an average of 7 oxyethylene units per molecule) to NEODENE 16 (at least 92% C 16 and at least 94% normal alpha olefin) to hexylene glycol. The results are presented in Table I . - 20 - - 22 - blend with NEODOL 25-3. Results indicate a very high flotation efficiency in removing visible ink particles. No additional visible ink particles were removed in the subsequent washing step. The brightness values in Example 6 were significantly less than obtained in Examples 1-5 using alpha-olefins in the deinking agent. This indicates that 3:1 blends of NEODOL 25-3 and the internal olefin 10 1518 were less effective in providing high brightness deinked pulp. Compared to Examples 1-5, more bleaching agent would be needed to provide a given target brightness value. No deinking agent was in Comparative Example A. Not surprisingly, residual ink surface area was much higher and ink removal efficiency was lower than in Examples 1-6. Brightness was also significantly lower in the absence of a deinking agent. In Comparative Example B, the highly effective deinking agent was taken from U.S. Patent 4,561,933. A predominantly linear alcohol, NEODOL 25 was substituted for the alpha-olefins used in Examples 1-5. Deinking agents of this type used in Comparative Example B are used commercially to deink office waste paper containing paper printed with electrostatic inks. Comparative Example B indicates that flotation ink removal was quite high, comparable to that obtained in Examples 1-5. However, deinked pulp brightness was significantly lower than obtained in Examples 1-5. This indicates more microscopic ink particles remain in the Comparative Example B pulp. Higher levels of costly bleaching agents would be required to attain a target brightness with the Comparative Example B deinked pulp than with the deinked pulp of Examples 1-5. Thus, the presence of the alpha-olefin results in economic advantages associated with reduced bleaching costs. Discussion of the Results of Examples 1-10 and Comparative Examples A-D As can be seen in Table I, 3:1 blends of NEODOL 25-3 and NEODENE alpha-olefins (Examples 1-5) provided very high visible ink particle removal after sequential flotation - wash deinking. With the exception of entry 2, ink removal efficiency in the flotation step was greater than 99%. The high brightness values indicate that few microscopic ink particles remain. (The significant economic advantage compared to other electrostatic ink deinking agents (Comparative Example B) is that significantly less bleaching agent would be required to increase pulp brightness to a target value. Examples 1-5 indicate that 3:1 NEODOL 25-3 blends with alpha-olefins having carbon numbers from 10 to 20-24 were highly effective in removing visible ink particles while producing a high brightness pulp. In some examples, additional ink was removed in the post flotation washing step. Why this occurred in some examples and not others is not presently understood. The losses of fiber and filler particles in the washing step may account for the increased residual ink content after washing compared to after flotation. Deinked pulp residual ink surface area of 5 ppm or less is considered more than adequate to use the pulp in making high value printing and writing paper. Deinked pulp residual ink surface area of 50 ppm or less is considered adequate to produce tissue products from the pulp. The residual ink surface area obtained in entries 4 and 5 indicate this deinked pulp can be used to produce high value printing and writing paper. The deinked pulp produced in the other tests can be used to produce tissue products. In Example 6 of Table, I, an internal olefin, IO 1518, was used instead of an alpha-olefin in a 3:1 - 24 - alpha-olefins can provide highly effective deinking agents . Hexylene glycol is an additive that may be used to both improve product liquidity at low temperatures and, as comparison of Example 9 and Example 7 indicate, to increase ink removal efficiency. In Example 9, 1 part of hexylene glycol was added to the 3:1 blend of NEODOL 45-7 and NEODENE 16 used in Example 7. In Example 9, no visible ink particles could be detected after flotation. The residual ink particle surface area permits this deinked pulp to be used to manufacture high value printing and writing paper. The deinked sheet brightness is equivalent to that of the unprinted paper, indicating that virtually no pulp bleaching would be required. The high brightness value suggests that little, if any, microscopic ink particles are present in the deinked pulp. The increase in performance over Example 7, particularly increased brightness, could be attributed to the presence of the hexylene glycol in the deinking agent. In Example 9 and Example 10, the hexylene glycol comprises 20% of the deinking agent. However, the ratio of NEODOL 45-7:NEODENE olefin was changed from 3:1 to 1:1. In addition, the NEODENE olefin was changed from NEODENE 16 in Example 9 to NEODENE 14 in Example 10. Visible ink particle removal remained excellent despite those changes. The residual ink surface area after flotation was low enough in Example 10 for this pulp to be used to produce high value printing and writing paper. However, the Example 10 brightness level, while quite high, was significantly less than obtained in Example 9. Comparison of Examples 9 and 10 suggests that the right amount of alpha-olefin and the alpha-olefin carbon number are both important in maximizing brightness when using In Comparative Example C, a predominantly linear and primary alcohol (NEODOL 1) was used instead of a predominantly linear and primary alcohol ethoxylate. Comparison to Example 2 which used the same alpha-olefin, NEODENE 14, indicated much lower ink removal efficiency and consequently a much higher residual ink surface area were obtained in Comparative Example C. Comparison of these examples indicates that, for high effectiveness, the alcohol ethoxylate is a required component of the deinking agent. In Example 7, a water soluble alcohol ethoxylate was used instead of the oil soluble NEODOL 25-3 used in Example 4. Very high ink removal efficiency was obtained and the residual ink surface area was more than adequate for the deinked pulp to be used in the manufacture of tissue products. The residual ink surface area suggests that, with a modest amount of additional processing, residual ink content could be reduced enough to manufacture high value printing and writing grade paper from the pulp. The Example 7 deinked pulp brightness value, while significantly less than obtained in Example 4, was still quite high. In Example 8, a linear saturated hydrocarbon containing no olefinic carbon - carbon double bonds was used instead of the predominantly linear alpha-olefin used in Example 7. Visible ink particle removal efficiency was very high and the residual ink particle surface area was low enough that his pulp could be used to manufacture high value printing and writing paper. Deinked pulp brightness was quite high indicating that only relatively small amounts of expensive bleaching chemicals would be needed to process this pulp. Example 8 suggests that, in combination with alcohol ethoxylates, linear saturated hydrocarbons as well as - 26 - Hydrapulping and Deinking. Deionized water was heated to 40-45 °C. Sodium hydroxide pentahydrate was added to adjust the pH to about 9. To this was added 0.75 millilitres of the deinking agent (0.25% weight calculated on the weight of the pulp) . A slurry of about 12% consistency was prepared by adding 150 grams of shredded xerographically printed paper and 150 grams of shredded ledger printed paper. This slurry was mixed for 30 minutes in an Adirondack, Formax 450 pulper on the high speed stir setting. This slurry was separated into two equal portions. One portion of the slurry was made into sheets using Buchner funnel filtration. The other portion was subjected to flotation. Flotation. Deionized water was heated to 40-45 °C and 2 litres placed in a Denver Flotation Machine. This unit consists of a stir motor, an impeller shaft and stirrer blade and a container for the pulp slurry. As the slurry is stirred, air is drawn down the hollow stirrer shaft and exits at the stirrer blades through small holes. The air bubbles created in the fashion rise through the pulp slurry taking ink particles with them. The froth at the top of the container is removed to separate the ink particles from the pulp slurry. The pulp slurry was added to the container and diluted to a total volume of 2.5 litres using additional 40°-45 °C tap water. Pulp slurry consistency was about 1.0% by weight. This mixture was stirred for 3 minutes at 1200 revolutions per minute while slurry foam was skimmed off and collected. The slurry was decanted from the flotation cell without pulp loss. Paper Making. Deinking process performance was measured by making paper from the deinked pulp and analyzing the paper for brightness and visible ink deinking agents containing alcohol ethoxylate, alpha-olefin and hexylene glycol. In Comparative Example D, a predominantly linear alcohol, NEODOL 45, was used instead of the alpha-olefin used in Example 10. Comparison of the two examples indicates that omission of the alpha-olefin from the deinking agent composition reduced visible ink particle removal efficiency. Unlike the deinked pulp after the Example 10 flotation, the Comparative Example D pulp could not be used to manufacture high value printing and writing paper although pulp quality was adequate to manufacture tissue product. The comparison of Example 10 and Comparative Example D indicates that the alpha-olefin is a required component of the deinking agent for maximum removal of visible ink particles to be achieved. Example ll This example illustrates the deinking of a 50:50 mixture of xerographically printed and ledger printed paper carried out using a deinking agent comprising a 7.5:1:1.5 ratio of NEODOL 45-7 (a mixture of C 14 to C 15 predominantly linear and primary alcohols, about 52 %wt . c 14 anc ^ 48 ^ t - c 15' containing an average of 7 oxyethylene units per molecule) to NEODENE 14 (at least 95% C j _4 and at least 94% normal alpha olefin) to NEODOL 45 (a mixture of C]_4 to C15 predominantly linear and primary alcohols, about 52 %wt . C^ _ and 48 %wt. C_ $ ) . To test the performance of the invention, the following procedures were carried out for the deinking of mixed xerographically printed and laser printed wastepaper. Sample Preparation. Mixed xerographically printed and laser printed paper was aged at least three days and then shredded by hand and mixed well. Multiple copies of the same printed page were used. - 28 - Systems ASA 2000 Image Analyzer. The visible ink particle count (in parts per million) was determined for particles larger in area than 0.02 square millimetres. The results of these tests are presented in Table II. Example 12 The procedures of Example 11 were repeated with the exception that the deinking agent used was a 8:1:1 ratio of NEODOL 45-7 (a mixture of Cχ to C3.5 predominantly linear and primary alcohols, about 52 %wt. C14 and 48 %wt . C15 containing an average of 7 oxyethylene units per molecule) to NEODENE 14 (at least 95% C 14 and at least 94% normal alpha olefin) to NEODOL 45 (a mixture of C ] _4 to C ] _5 predominantly linear and primary alcohols, about 52 %wt. C14 and 48 %wt . C 15 ) . The results are presented in Table II. Example 13 The procedures of Example 11 were repeated with the exception that the deinking agent used was a 7:2:1 ratio of NEODOL 45-7 (a mixture of C14 to C15 predominantly linear and primary alcohols, about 52 %wt . C14 and 48 %wt . C ] _5 containing an average of 7 oxyethylene units per molecule) to NEODENE 14 (at least 95% C 14 and at least 94% normal alpha olefin) to NEODOL 45 (a mixture of C14 to C ] _5 predominantly linear and primary alcohols, about 52 %wt . C 1 and 48 %wt . C 15 ) . The results are presented in Table II. Example 14 The procedures of Example 11 were repeated with the exception that the deinking agent used was a 5.1:1.0:0.7:0.8 ratio of NEODOL 45-7 (a mixture of C 14 to C__ predominantly linear and primary alcohols, about 52 %wt . C ] _4 and 48 %wt . C^s containing an average of 7 oxyethylene units per molecule) to NEODENE 14 (at least 95% C 14 and at least 94% normal alpha olefin) to NEODOL 45 (a mixture of C14 to C15 predominantly linear particles. The standard of comparison for determining the percent of visible ink particle removed was the paper sheets made immediately after pulping. The pulp was divided into four portions so that at least three, and preferably four, handsheets each weighing 2-4 grams could be made. Each portion of pulp was dispensed in 40°-45 °C tap water and poured into a Buchner funnel fitted with Whatman Number 40 filter paper and placed in a vacuum flask connected to a house vacuum line. In the Buchner funnel, pulp was deposited forming a wet sheet, through which water drained rapidly. The sheet thus formed was covered with two pieces of thick dry filter paper (two above and two below) and the several layers then squeezed by rolling with a 13.6 kg rolling pin. The layers were next removed from the apparatus and the prepared sheet separated from the filter papers. Finally, the prepared sheet was placed between four thick filter papers (two above and two below) , pressed with a force of 445 kPa, and dried between fresh thick filter papers at room temperature in the dark for about 24 hours. The papers ("Buchner funnel pads") thus prepared were analyzed for brightness. Brightness measurements were made on the basis of percent light reflection from the sheet, using a standardized Technidyne Technibrite ERIC 950 meter. Eight measurements were made for each sheet, one at the center of each of four quadrants on both sides, and the eight values averaged for the sheet. Normally, the eight separate measurements varied over a range of no more than 1%. Reported brightness readings were the average of the brightness results for at least three similarly processed sheets. The hand sheets were inspected for visible ink particles using an image analysis method. Images of the entire sheet were directly input into an Applied Vision and primary alcohols, about 52 %wt. C_4 and 48 %wt . C ι5 ) to hexylene glycol . The results are presented in Table II. Comparative Example E The procedures of Example 11 were repeated with the exception that no deinking agent was used. The results are presented in Table II. Comparative Example F The procedures of Example 1 were repeated with the exception that the deinking agent used was a 3:1 ratio of NEODOL 45-7 (a mixture of C 14 to C 5 predominantly linear and primary alcohols, about 52 %wt . C 14 and 48 %wt. C- 1 5 containing an average of 7 oxyethylene units per molecule) to NEODOL 45 (a mixture of C 14 to C15 predominantly linear and primary alcohols, about 52 %wt . C 14 and 48 %wt. C 15 ) . The results are presented in Table II. Comparative Example G The procedures of Example 1 were repeated with the exception that the deinking agent used was a 3 :1 ratio of NEODOL 45-7 (a mixture of C 14 to C 15 predominantly linear and primary alcohols, about 52 %wt . C14 and 48 %wt . C^ containing an average of 7 oxyethylene units per molecule) to NEODENE 14 (at least 95% C 14 and at least 94% normal alpha olefin) . The results are presented in Table II. - 32 - surface area obtained with Comparative Example F was much higher than that obtained with ternary systems. In Comparative Example G, a binary system with a 3:1 NEODOL 45-7:NEODENE 14, was used. Brightness obtained with this system was much lower than with the ternary systems in Example 11, Example 12, and Example 13. No significant ink removal was observed with this system. The comparison of Example 11, Example 13, and Example 14 with Comparative Examples F and G indicate that all three components are necessary in the deinking agent in order for maximum removal of visible ink particles to be achieved. Discussion of the Results of Examples 11-14 and Comparative Examples E-G As can be seen in Table II, ternary blends of NEODOL 45-7, NEODENE 14 and NEODOL 45 provided very high visible ink particle removal after flotation in comparison to binary system 3:1 NEODOL 45-7 and NEODENE 14 (Comparative Example G) . Examples 11, 12, and 13 indicate that these ternary blends are highly effective in removing visible ink particles while producing a high brightness pulp. A ternary blend with ratio 7.5:1,0:1.5, NEODOL 45-7; NEODENE 14:NEODOL 45 (Example 11) was found to be optimum for removing visible ink. Deinked pulp residual ink surface was also lower for ternary systems versus binary systems. No deinking agent was used in Comparative Example E. Not surprisingly, residual ink surfactant was much higher and no visible ink was removed. Brightness was also significantly lower in the absence of a deinking agent. Hexylene glycol was added to increase liquidity and stability of formula at lower temperatures and to increase ink removal efficiency. Hexylene glycol was added to a deinking agent containing the optimum ratio for surfactant system (7.5:1.0.0:1.5, NEODENE 14; NEODOL 45) . In Example 14, 2.8 parts of hexylene was added to 6.8 parts of Example 11. Example 14 gave an equal visible ink removal equal to optimum system (Example 11) , but showed a significant improvement in residual ink surface area. In Comparative Example F, a binary system with 3:1 NEODOL 45-7 and NEODOL 45 was used. Brightness obtained with this system was comparable to brightness obtained with ternary systems. The visible ink removal for this system was significantly lower than the ternary systems of Example 11 and Example 13. Also, the residual ink - 34 - 5. The process of claim 3 wherein said second component is a saturated hydrocarbon selected from the group consisting of decane, dodecane, tetradecane, hexadecane, octadecane and mixtures thereof. 6. The process of claim 1 wherein said deinking agent has a ratio of first component to second component in the range of from 10:1 to 1:1. 7. The process of claim 1 wherein the aqueous medium contains between 0.5 and 30 percent by weight of pulp and step b) of the process is carried out at a temperature in the range of from 30 °C to 95 °C. 8. The process of claim 1 wherein the aqueous medium of alkaline pH has a pH in the range of from 8 to 10. 9. The process of claim 1 wherein in step b) said deinking agent is added in a quantity between 0.1 to 1.0 percent by weight. 10. The process of claim 1 wherein said deinking agent additionally contains a third component selected from the group consisting of alcohols, propoxyethoxylates, • glycols, fatty acids and fatty acid propoxyethoxylates having from 8 to 20 carbon atoms, and mixtures thereof. 11. The process of claim 10 wherein said third component is a detergent-range alcohol component having from 8 to 20 carbon atoms. 12. The process of claim 10 or 11 wherein said deinking agent has a ratio of first:second:third component in the range of from 10:1:1 to 2:1:1.

Claims: C I M S 1. A process for the deinking of office wastepaper stocks which comprises: a) converting the wastepaper to a pulp, b) contacting the pulp with an aqueous medium of alkaline pH containing between 0.05 and 2 percent by weight, calculated on a dry weight basis of the pulp, of a deinkinq agent comprising a first component comprising at least one ethylene oxide adduct of a detergent-range alcohol having in the range of from 8 to 20 carbon atoms and an average of from 3 to 20 oxyethylene units per molecule of alcohol, and a second component selected from the group consisting of one or more detergent-range olefins having from 8 to 22 carbon atoms, one or more saturated hydrocarbons having from 8 to 20 carbon atoms, and mixtures thereof, and c) treating the resulting pulp-containing medium by washing or flotation to remove suspended ink therefrom. 2. The process of claim 1 wherein said first component is an ethylene oxide adduct of a detergent-range alcohol having from 12 to 18 carbon atoms and an average of from 3 to 13 oxyethylene units per molecule of alcohol. 3. The process of claim 1 wherein said second component is selected from the group consisting of one or more detergent-range olefins having from 12 to 18 carbon atoms, one or more saturated hydrocarbons having from 12 to 16 carbon atoms, and mixtures thereof. 4. The process of claim 3 wherein said second component is a detergent-range olefin having from 12 to 18 carbon atoms. ., iformaQon on patent family members Patent document Publication Patent family Publication ciled in search report date member(s) date EP-A-0510954 28-10-92 US-A- 5200034 06-04-93 US-A- 5141598 25-08-92 AU-B- 657747 23-03-95 AU-A- 1477192 29-10-92 CA-A- 2065712 26-10-92 NZ-A- 242280 25-02-94 US-A- 5248388 28-09-93 US-A- 5302242 12-04-94 US-A- 5282997 01-02-94 US-A-4311552 19-01-82 CA-A- 1144310 12-04-83 JP-A- 55116891 08-09-80 US-A-3501373 17-03-70 NONE Form PCT.1SA 3I0 (paunt ramily annex) (July 1 2)

Inventors: BLANCO RUTH JAVIER, BORCHARDT JOHN KEITH, BLANCO, RUTH, JAVIER, BORCHARDT, JOHN, KEITH
Applicants: SHELL CANADA LTD, SHELL INT RESEARCH, SHELL CANADA LIMITED, SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V.
Application year: 1996
Main classification: D21C5
IPC codes: D21C5