Title of Invention

AN ENZYME COMPOSITION FOR INK REMOVAL FROM RECYCLED PAPER COMPOSITION

Abstract

An enzyme composition for ink removal from recycled paper composition comprising 45- 55 % by weight of cellulase; 30- 35 % by weight of xy1anase; 5-10 % by weight of pectinase; 5-10 % by weight of amylase and the balance if any a surfactant upto 100 % by weight. The present invention also comprises a enzymatic process for ink removal from recycled paper- pulp using the said novel enzyme composition to obtain a regenerated pulp having a high brightness degree and a low content of residual ink.

Full Text

Field of invention The present invention relates to a novel enzyme composition for removal of ink from paper. This invention is particularly useful to the papermaking industry using recycled pulp as the raw material for making paper. More specifically its object is a new method for treating recycled paper pulp using a novel enzyme composition to remove ink particles from the pulp fiber and obtain a regenerated pulp having a high brightness degree and a low content of residual ink and having the desired SR degree. Background of invention Wastepaper has long served as a source of raw fiber material for papermaking. It has been standard practice in the art to reclaim wastepaper to allow the reclaimed paper fibers to be used as part or all of the stock of subsequent production of a variety of paper and paperboard products. Today, 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 wastepaper are becoming available with the increased participation by businesses in recycling. Because of the high quality cellulose fiber in office wastepaper, efficient ink removal is particularly desirable since excellent quality, high value products such as office stationery can be prepared. In the course of conventional paper reclamation, ink-removing procedures include steps for converting the wastepaper to pulp and contacting the pulp with an alkaline aqueous ink-removing medium containing, a chemical ink-removing agent. The physical pulping and the alkalinity of the aqueous medium cause the partial removal of ink from the pulp fiber. The ink-removing agent completes this removal and produces an aqueous suspension and/or dispersion of the ink particles. The resulting mixture is subsequently treated to separate the suspended/dispersed ink from the pulp. The separation is done by flotation and/or washing techniques known in the art. Conventional ink-removing chemicals comprise a complex mixture of chemicals, e.g., sodium hydroxide, sodium silicate, chelating agents, hydrogen peroxide, surfactants, dispersants, collector chemicals and agglomeration chemicals. Generally, including a significant amount of alkaline material is standard in the art. It is believed that the alkaline material is needed for good saponification and hydrolysis of the ink resins as well as enhancement of fiber flexibility. The pH of the pulp during the ink-removing process is usually from 9.5 to about 11. Exposing the cellulosic fibers to this degree of alkalinity tends to cause yellowing of the fibers; so, it is generally necessary to add an oxidative or reductive bleaching agent such as peroxide, formamidine sulfinic acid or sodium hydrosulfite. The use of this complex and highly alkaline mixture of chemicals is undesirable since the liquor that results from the ink-removing process presents significant environmental disposal problems. There is a need for a method of ink-removing that operates under slightly acidic to slightly alkaline or preferably neutral pH conditions and utilizes a simple combination of chemicals. Such a method could result in waste liquors with significantly reduced disposal problems. Conventional processes have not been particularly successful in specific application to xerographically printed and laser printed paper found in office wastepaper. The difficulty encountered in the ink-removal of these fused toner papers (laser and Xerox produced) has been attributed to the character of the electrostatic ink, specifically to the binder, which is fundamentally different from that used in other printing processes. For example, in distinction to the common oil or resin binders of other inks, the electrostatic ink binder is typically a polymeric material, e.g., polystyrene and polybutadiene, which during the printing process is fixed to the paper by application of pressure and heat. It is the ink-fusing action of the copier or laser printer that upon repulping results in large, plate-like structures which are typically too large to be removed by washing or flotation and too flat to be removed by screens and cleaners. The approach that several chemical companies have taken is to chemically modify the surface of the toner flakes such that agglomeration will occur. The substantially larger particles will then be removed by slotted pressure screens and forward centrifugal cleaners. In the papermaking industry a certain number of methods are known which call for enzyme compositions. US 5,231,022 and 5,318,905 teach the use of highly alkaline cellulase enzymes for use in the ink-removal of waste newspaper. The enzyme optimally operates at a pH of about 9.5 to about 10.5. Japan Published Application No. 59009299 teaches a method for ink-removal from waste newspaper and magazine print. The method involves the combined use of a surfactant with an enzyme. Cellulase enzymes are suggested for use, particularly those, which operate effectively under basic pH conditions (i.e., pH of 8.0 to 11.5). The reference does not disclose nor suggest that its teachings can be utilized for ink-removal of mixed office waste, which utilizes inks and print processing conditions that far differ from those used in newsprint and magazine print. Despite the above teachings, there exists a clear need in the art for a method, which effectively functions to remove ink from a mixed furnish of recycled paper. The instant innovation is operative at slightly acidic to slightly neutral pH aqueous environments. SUMMARY OF THE INVENTION Removing ink from recycled paper pulp derived from various sources to get the a pulp substantially free of ink and having desired pulp freeness value of 22°SR can be achieved by an alternate method to conventional chemical treatment of the pulp, which involves enzymatic treatment of the pulp. The method in accordance with the instant invention is applied to recycled paper furnish of various origin. In accordance with the invention, a novel enzyme composition containing Cellulase, Xylanase, Pectinase, Amylase and optionally a surfactant and Filler-rest; is reacted with recycled paper pulp. It has been noted that, such treatment enables the efficient removal of ink from the pulp and gives it an increased degree of brightness while the degree of SR of the treated pulp to be brought to the desired level of 22°SR. At the same time have no undesirable effect on the mechanical characteristics of the papers manufactured from such pulp. The enzyme is seen to reduce the energy required for processing the recycled pulp. It also improves the drainage rates of the fibres over the paper machine wire. Addition of the said enzyme is done in the pulper, while slushing of pulp-sheets, to ensure uniform mixing of enzyme with pulp. The treated pulps can be intended for the most varied uses in the papermaking field. Mixed recycled paper furnish of Coated base stock (CBS)/un-printed white paper, plastic window envelopes (PWE) and Money folder color ledger(MCL)/sorted color ledger(SCL)/sorted white ledger(SWL) was diluted with machine backwater to about 10% consistency and treated with the enzyme composition of Reference Example 1 and Filler-rest. The slurry was transferred to a pulper and slushed (without) load for about 7 minutes with the enzyme composition dosed at 0.3 Kg/T and 0.5g/T of the pulp. The slurry was allowed to stand at 55°C at a pH of 6.5 and provided the desired reaction time of 30 to 45 min. At the end of the reaction time the released ink was separated from the pulp slurry by froth flotation or water washing or a combination of both. EXAMPLE 2 Mixed recycled paper furnish of Coated base stock (CBS)/un-printed white j ; paper, sorted office packs (SOP) and Money folder color ledger ,(MCL)/sorted color ledger(SCL)/sorted white ledger(SWL) was diluted with .machine backwater to about 8% consistency and treated with the enzyme of Reference Example 1 and Filler-rest, The slurry was transferred to a pulper and slushed (without) load for about 7 minutes with the enzyme composition dosed at 0.3 Kg/T and 0.4Kg/T of the pulp. The slurry was allowed to stand at 50°C at a pH of 6.7 and provided the desired reaction time of 20 to 45 min. At the end of the reaction time the released ink was separated from the pulp slurry by froth flotation, water washing or a combination of both. EXAMPLE 3 The recycled paper furnish of various origin such as sorted office packs (SOP) or Coated base stock (CBS)Ain-printed white paper or plastic window envelopes (PWE) or Light printed solid bleached sulphate (LPBS). A mixed furnish of the above was diluted with machine backwater to about 8% consistency and treated with the enzyme composition of Reference Example 1 and Filler-rest. The slurry was transferred to a pulper and slushed (without) load for about 7 minutes with the enzyme composition dosed at 0.3 Kg/T and 0.5Kg/T of the pulp. The slurry was allowed to stand at 45°C at a pH of 6.2 and provided the desired reaction time of 30 to 45 min. At the end of the reaction time the released ink was separated from the pulp slurry by flotation, water washing or a combination of both. The recycled paper furnish of various origin such as sorted office packs ,(SOP) or Coated base stock (CBS)/un-printed white paper or Indian records(IR) or post consumer(PC) or a mixed furnish of the above is was diluted with machine backwater to about 8% consistency and treated with the enzyme composition of Reference Example 1 and Filler-rest. The slurry was transferred to a pulper and slushed (without) load for about 7 minutes with the enzyme composition dosed at 0.3 Kg/T and 0.5g/T of the pulp. The slurry was allowed to stand at 55°C at a pH of 6.7 and provide the desired reaction time of 30 to 45 mins. At the end of the reaction time the released ink was separated from the pulp slurry by flotation, water washing or a combination of both. We Claim 1. An enzyme composition for ink removal from recycled paper comprising: - 45- 55 % by weight of cellulase - 30- 35 % by weight of xylanase - 5-10 % by weight of pectinase - 5-10 % by weight of amylase and the balance if any surfactant upto 100% by weight 2. An enzyme composition as claimed in claim 1 wherein the ingredients are added in the following proportions: - 51. 7 % by weight of cellulase - 34. 5 % by weight of xylanase - 6.9 % by weight of pectinase and - 6.9 % by weight of amylase 3. An enzyme composition as claimed in claim 1 wherein the ingredients are added in the following proportions: - 44.1 % by weight of cellulase - 29.4 % by weight of xylanase - 5.9 % by weight of pectinase - 5.9 % by weight of amylase and - 14. 7 % by weight of surfactant. 4. A novel enzyme composition as claimed in claim 1 or 3 wherein said surfactants is non-ionic surfactants. 5. A process for ink removal from recycled paper pulp using the enzyme composition as claimed in any preceding claims, which comprises the step of- (a) preparing slurry of paper pulp from recycled paper, (b) subjecting the slurry of recycled paper pulp to the enzyme composition at 20°C-80°C for 15-60 min at a pH of 5.0-8.0, (c) removing the ink particles from the pulp slurry by froth floatation or washing, and (d) obtaining a regenerated pulp. 6. A process as claimed in claim 5, wherein the enzyme composition includes a filler. 7. A process as claimed in claim 5, wherein the enzyme composition comprises: - 45- 55 % by weight of cellulase - 30- 35 % by weight of xylanase - 5-10 % by weight of pectinase - 5 -10 % by weight of amylase and the balance if any a surfactant upto 100% by weight 8. A process as claimed in claim 5, wherein the enzyme composition comprises: 44.1 % by weight of cellulase 29.4 % by weight of xylanase 5.9 % by weight of pectinase 5.9% by weight of amylase and 14. 7 % by weight of surfactant. 9. A process as claimed in claim 5 wherein, the enzyme composition treatment is followed by filtration. 10. A process as claimed in claim 5 wherein, the enzymatic treatment of the said pulp with the enzyme composition is done at 45 °C- 55°C. 11. A process as claimed in claim 5 wherein, the recycled paper pulps is selected from sorted office packs (SOP), Coated base stock (CBS or un-printed white paper), plastic window envelopes (PWE), Indian records (1R), post consumer (PC), Light printed solid bleached sulphate (LPBS), Money folder color ledger (MCL), sorted color ledger (SCL), sorted white ledger(SWL) or a mixture of one or more of these. 12. A process as claimed in claim 5 wherein in step (a), the slurry of paper-pulp is made to a consistency of 8%-10%. 13. A process as claimed in claim 5 wherein in step (a), the paper-pulp is treated with the enzyme composition for 20-45 mins. 14. A process as claimed in claim 5 wherein, the paper- pulp is treated with the enzyme composition at a pH of 6.2-6.7. 15. An enzyme composition substantially as herein described with reference to the fore-going examples. 16. A process for ink removal from recycled paper pulp using the enzyme composition substantially as herein described with reference to the fore-going examples.

Documents:

645-mas-2002- abstract.pdf

645-mas-2002- claims duplicate.pdf

645-mas-2002- claims original.pdf

645-mas-2002- correspondence others.pdf

645-mas-2002- correspondence po.pdf

645-mas-2002- description complete duplicate.pdf

645-mas-2002- description complete original.pdf

645-mas-2002- form 1.pdf

645-mas-2002- form 13.pdf

645-mas-2002- form 26.pdf

645-mas-2002- form 3.pdf