US20040000383A1 - Process for facilitating the use of high lignin containing waste paper in the manufacture of paper products - Google Patents

Process for facilitating the use of high lignin containing waste paper in the manufacture of paper products Download PDF

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US20040000383A1
US20040000383A1 US10/425,691 US42569103A US2004000383A1 US 20040000383 A1 US20040000383 A1 US 20040000383A1 US 42569103 A US42569103 A US 42569103A US 2004000383 A1 US2004000383 A1 US 2004000383A1
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delta
values
brightness
waste paper
handsheets
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US10/425,691
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Henry Chou
Hazen Thomas
Andrew Palm
Terry Witkowski
Robert Clausing
Stephanie Keen
David DiPietro
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Fort James Corp
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Fort James Corp
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Priority to US10/425,691 priority Critical patent/US20040000383A1/en
Assigned to FORT JAMES CORPORATION reassignment FORT JAMES CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: CHOU, HENRY, WITKOWSKI, TERRY P., THOMAS, HAZEN C., CLAUSING, ROBERT J., KEEN, STEPHANIE, PALM, ANDREW C., DIPIETRO, DAVID J.
Publication of US20040000383A1 publication Critical patent/US20040000383A1/en
Assigned to CITICORP NORTH AMERICA, INC. reassignment CITICORP NORTH AMERICA, INC. SECURITY AGREEMENT Assignors: ASHLEY, DREW & NORTHERN RAILWAY COMPANY, BLUE RAPIDS RAILWAY COMPANY, BLUEYELLOW, LLC, BROWN BOARD HOLDING, INC., BRUNSWICK CELLULOSE, INC., BRUNSWICK PULP LAND COMPANY, INC., CECORR, INC., COLOR-BOX, LLC, CP&P, INC., ENCADRIA STAFFING SOLUTIONS, INC., FORT JAMES CAMAS L.L.C., FORT JAMES CORPORATION, FORT JAMES GREEN BAY L.L.C., FORT JAMES INTERNATIONAL HOLDINGS, LTD., FORT JAMES MAINE, INC., FORT JAMES NORTHWEST L.L.C., FORT JAMES OPERATING COMPANY, GEORGIA-PACIFIC ASIA, INC., GEORGIA-PACIFIC CHILDCARE CENTER, LLC, GEORGIA-PACIFIC FINANCE, LLC, GEORGIA-PACIFIC FOREIGN HOLDINGS, INC., GEORGIA-PACIFIC HOLDINGS, INC., GEORGIA-PACIFIC INVESTMENT, INC., GEORGIA-PACIFIC RESINS, INC., GEORGIA-PACIFIC WEST, INC., GLOSTER SOUTHERN RAILROAD COMPANY, G-P GYPSUM CORPORATION, G-P OREGON, INC., GREAT NORTHERN NEKOOSA CORPORATION, GREAT SOUTHERN PAPER COMPANY, KMHC, INCORPORATED, KOCH CELLULOSE AMERICA MARKETING, LLC, KOCH CELLULOSE, LLC, KOCH FOREST PRODUCTS HOLDING, LLC, KOCH RENEWABLE RESOURCES, LLC, KOCH WORLDWIDE INVESTMENTS, INC., LEAF RIVER CELLULOSE, LLC, LEAF RIVER FOREST PRODUCTS, INC., MILLENNIUM PACKAGING SOLUTIONS, LLC, NEKOOSA PACKAGING CORPORATION, NEKOOSA PAPERS INC., OLD AUGUSTA RAILROAD, LLC, OLD PINE BELT RAILROAD COMPANY, PHOENIX ATHLETIC CLUB, INC., PRIM COMPANY L.L.C., SOUTHWEST MILLWORK AND SPECIALTIES, INC., TOMAHAWK LAND COMPANY, WEST GEORGIA MANUFACTURING COMPANY, XRS, INC.
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    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21GCALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
    • D21G9/00Other accessories for paper-making machines
    • D21G9/0009Paper-making control systems
    • D21G9/0018Paper-making control systems controlling the stock preparation
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H11/00Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
    • D21H11/08Mechanical or thermomechanical pulp
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H11/00Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
    • D21H11/14Secondary fibres
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/34Paper
    • G01N33/343Paper paper pulp
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21CPRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C5/00Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
    • D21C5/02Working-up waste paper
    • D21C5/025De-inking
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21CPRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C9/00After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
    • D21C9/10Bleaching ; Apparatus therefor
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02WCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00Technologies for solid waste management
    • Y02W30/50Reuse, recycling or recovery technologies
    • Y02W30/64Paper recycling

Definitions

  • This application relates to recycling waste paper. Before waste paper can be reused, it is subject to pulping, deinking and bleaching processes. The cost of the waste paper and bleaching processes constitute a major part of the cost of the manufacturing cost for the production of paper products. Prior art methods controlled deinking and bleaching based upon the brightness of the incoming fiber with the attempt being made to deink and then bleach to a target brightness level.
  • This process comprises preparing a pulp from recycle furnish to form secondary fiber and preparing an absorbent sheet from said secondary papermaking fiber, characterizing the initial color of said absorbent sheet, staining said absorbent sheet with a phloroglucinol stain and characterizing the color of said absorbent sheet.
  • the process depends on comparing the color of the stained sheet with initial color and selecting a target paper product based on the comparison.
  • the characterization comprises a parameter selected consisting of a lightness parameter, a red green parameter and a yellow blue parameter.
  • CIE L*, a*, b* and brightness values are used to determine the percent groundwood in the feedstock. This is done by obtaining delta L*, a*, b* and brightness values as shown in FIGS. 1 - 3 , 12 - 15 and 19 - 20 .
  • delta a*, delta b*, delta L* and delta brightness values are suitable in determining untreated groundwood content in the sheet and thus the suitability of the pulp for predetermined commercial applications.
  • Suitable delta a* range is 0-20
  • delta L* range is 0 to 28
  • delta b* range is ⁇ 2 to 17
  • delta brightness range is 5 to 21 to produce 60 to 85 GE brightness pulp.
  • unbleached groundwood content correlates very closely with the change in the delta a*, delta b*, delta L* and delta brightness value using the spectrophotometer before and after staining of the handsheets.
  • a delta a* value of less than 10, 10-20 and over 20 provide guidance as to the bleaching and deinking process to employ to obtain paper products exhibiting GE brightness values of 60 to 85.
  • the delta a* value is 20 or above, the optimum use of the pulp is as unbleached brown stock or semi-bleached stock (having a GE brightness of about 40).
  • Table 1 provides the approximate bleaching process selection based on delta a*, delta b*, delta L*, and delta brightness values: TABLE 1 Bleaching Process Selection Based on delta a*, delta b*, delta L*, and delta brightness Bleaching Process delta a* delta b* delta L* delta brightness Conventional Hypo ⁇ 10 ⁇ 7 ⁇ 14 ⁇ 21 Non-delignified 10-20 7-17 14-28 21-31 Semi-bleaching >20 >17 >28 >31
  • Another aspect of our invention is to control the bleaching of unbleached fibers to maintain the pulp fed to a deinking and bleaching process within the targeted range to achieve the predetermined brightness levels of the paper products.
  • the primary advantage of our process is the speed with which the delta a*, delta b*, delta L* and delta brightness results can be obtained, usually in ten minutes or less, 5-7 minutes being the normal range.
  • the spectrophotometric and staining process of this invention is able to distinguish between modified and unmodified lignins.
  • TAPPI Method T236-OM-99 lumps useful BCTMP lignins with unmodified lignins thus causing higher processing costs.
  • the aforementioned TAPPI Method requires twenty minutes to be carried out while our process can be carried out in 5 to 10 minutes.
  • BCTMP processes shift the spectral response into the invisible region making their use acceptable without additional bleaching to produce paper products having commercially acceptable brightness values.
  • the TAPPI Method T236-OM-99 measures only gross lignin content and thus under predicts brightness attainable with the pulp stream containing modified lignins.
  • TAPPI Method of determining lignin content is used to control the amount of the higher grade waste papers added to the waste paper stream, more expensive higher grades will be used than is necessary to achieve the targeted brightness of the paper products.
  • Our process avoids this costly waste as the amount of high grade waste paper required to reach the targeted brightness is predicted more accurately and the bias toward mixing in too much high grade waste paper can be substantially reduced.
  • a very important aspect of our invention is that it enables a more precise control of finished stock brightness.
  • Our process predicts the finished product more accurately and therefore will usually result in less variation of the finished stock brightness and higher usage of the groundwood containing waste paper to meet the same target brightness.
  • GE brightness values 60 to 85.
  • FIG. 1 is a graph illustrating the relationship between delta a* values and percent groundwood.
  • FIG. 2 is a graph illustrating the relationship between a* and percent groundwood.
  • FIG. 3 is a graph illustrating the relationship between the estimated percent groundwood and delta a*.
  • FIG. 4 is a graph illustrating the relationship between a* and reaction time. This graph demonstrates that a* value for handsheets can be obtained within five minutes after the handsheet is treated with phloroglucinol.
  • FIG. 5 is a graph illustrating the relationship between delta a* and kappa numbers obtained using TAPPI Method T236-OM-99.
  • FIG. 6 is a graph illustrating the relationship between kappa numbers and percent total groundwood using TAPPI Method T236-OM-99.
  • FIG. 7 is a graph illustrating the relationship between delta a* and kappa number. It should be noted that TAPPI Method T236-OM-99 includes in kappa numbers BCTMP treated groundwood fibers while the delta a* excludes these fibers and other fibers which have been chemically treated.
  • FIGS. 8 and 9 are graphs showing the relationship between the kappa number and percent of total groundwood.
  • FIG. 10 is a graph illustrating the relationship between a* and kappa numbers obtained by using TAPPI Method T236-OM-99.
  • FIG. 11 is a graph illustrating the relationship between delta b* and kappa numbers obtained by using TAPPI method T236-OM-99.
  • FIG. 12 is a graph illustrating delta b* versus percent groundwood.
  • FIG. 13 is a graph illustrating b* versus percent groundwood.
  • FIG. 14 is a graph illustrating the relationship between b* and Kappa numbers obtained by using TAPPI Method T236-OM-99.
  • FIG. 15 is a graph which illustrates the relationship between delta L* and percent groundwood.
  • FIG. 16 is a graph illustrating L* versus percent groundwood.
  • FIG. 17 is a graph illustrating the relationship between delta L* and Kappa numbers obtained by using TAPPI Method T236-OM-99.
  • FIG. 18 is a graph illustrating the relationship between L* and Kappa number obtained by using TAPPI Method T236-OM-99.
  • FIG. 19 is a graph illustrating delta brightness and percent groundwood.
  • FIG. 20 is a graph illustrating brightness and percent groundwood.
  • FIG. 21 is a graph illustrating the relationship between delta brightness and Kappa numbers obtained by using TAPPI Method T236-OM-99;
  • FIG. 22 is a graph illustrating the relationship between brightness and Kappa numbers obtained by using TAPPI Method T236-OM-99;
  • FIG. 23 is a graph illustrating transformed brightness versus percent groundwood.
  • FIG. 25 is a secondary fiber plant flow diagram.
  • FIG. 26 is a graph illustrating the relationship between delta a* and the kappa number.
  • Suitable CIE L*, a*, b* and brightness values are used to determine the percent groundwood in the feedstock. This is done by obtaining the delta L*, a*, b* and brightness values.
  • the Kappa number is the volume (in millimeters) of 0.1N potassium permanganate solution consumed by one gram of moisture-free pulp the results are corrected to 50% consumption of the permanganate added.
  • L*, a* and b* and brightness parameters are suitably measured using TAPPI Method T-524-OM-94. These are called Hunter color values.
  • a and b designate color as follows:
  • L denotes lightness increasing from 0 for black to 100 for perfect white
  • a shows redness when plus, green when minus and zero for grey
  • b represents yellowness when plus, blueness when minus and zero when grey.
  • the delta b* values versus percent groundwood are illustrated in FIG. 12. To obtain GE brightness values in the paper product of about 60 to 85 the delta b* values should be in the range of about ⁇ 2 to 17.
  • the delta L* values versus percent groundwood are illustrated in FIG. 15. To obtain GE brightness values in the paper product of about 60 to 85 the delta L* values should be about 0 to 28.
  • the delta brightness values versus percent groundwood are illustrated in FIG. 19. To obtain GE brightness values in the paper product of about 60 to 85 the delta brightness value should be about 5 to 21.
  • our invention provides a rapid process for determining chemically untreated groundwood in pulp derived from waste paper prior to it being charged to the deinking/bleaching system.
  • handsheets are made from the pulp undergoing evaluation and staining these handsheets with phloroglucinol stain This solution consists of 8.0 grams phloroglucinol, dihydrate, 100 ml ethyl alcohol and 100 ml concentrated hydrochloric acid.
  • Gretag MacBeth Color Eye 3100 spectrophotometer is used to measure the color value of the stained handsheet sample and compare it to unstained handsheet sample. The MacBeth spectrophotometer is calibrated to provide CIE L*, a* and b* measurements.
  • FIGS. 1 and 3 illustrate the correlation between percent chemically untreated groundwood and delta a*. Those values are very important to the paper manufacturer since if the delta a* value is less than 10 then conventional hypobleaching processes may be used to produce 60 to 85 GE brightness paper products. If the unbleached groundwood content incoming pulps is in the medium range as indicated by an average delta a* of 10 to 20, then a non-delignified bleaching technique, such as peroxide and/or hydrosulfide bleaching processes may be used to produce the 60 to 85 GE brightness paper products.
  • a non-delignified bleaching technique such as peroxide and/or hydrosulfide bleaching processes may be used to produce the 60 to 85 GE brightness paper products.
  • the pulp can be used for semi-bleached or unbleached stock generally known as brown stock.
  • delta a*, b*, L* and brightness values which give us control on what deinking/bleaching process to utilize. This, of course, depends on the amount of chemically untreated groundwood in the incoming pulp. Alternatively, we can use this same information to blend pulps to maximize the amount of groundwood utilized to achieve a paper product having commercially acceptable brightness properties. 60 to 85 GE brightness pulps are used to produce absorbent paper products such as tissues.
  • Our invention includes a process for utilizing chemically treated groundwood in addition to untreated groundwood. Since our delta values do not include chemically treated groundwood or groundwood which is derived from BCTMP treated waste paper. Thus, using TAPPI Method T236-OM-99, the kappa values for groundwood obtained in FIGS. 5, 7 and 8 overstate the amount of groundwood in the pulp since the chemically treated and BCTMP derived groundwood is reported as untreated groundwood. This reporting error results in the use of a more expensive wastepaper and deinking/bleaching process than would be required if our claimed process would be utilized to produce paper products exhibiting commercially acceptable brightness. These values usually are a 60 to 85 GE brightness value.
  • FIG. 25 shows the operation of the secondary fiber plant flow diagram.
  • Waste paper 100 is fed to pulper 101 and charged to drop tanks 1 ( 102 ), 2 ( 103 ) and 3 ( 104 ).
  • the ratio of the pulps from the three drop tanks is combined into the blend chest 106 .
  • the delta a* or alternatively the delta L* or delta b* or delta brightness testing is conducted on samples coming from the blend chest at point 107 .
  • the deinking system 108 is adjusted for the severity of ink removal treatment.
  • the severity of the bleaching system 109 is adjusted.
  • the deinked and bleached pulp is stored in the finished stock tank 110 from which it is fed into the paper making machines.
  • the regular unbleached pulp had the delta a* ranged from 11 to 19 and averaged 13.5 in one deinking process. This corresponds to a groundwood fiber content of 5% to 20%, averaging about 8%.
  • an improvement was made to control the pulp from the blend chest 106 having a delta a* value in the range of 16-18, and still maintained the same finished product brightness.
  • groundwood content 4% to 13% in the wastepaper furmish.
  • the groundwood content should be increased to about 15-20% when the deinked pulp from 108 is fed into the bleaching system 109 using Eopy bleach processes. This corresponds to a delta a* value of 16-18.
  • the delta a* can be obtained by subtracting initial a* from the final a* reading.
  • sample glass should be cleaned with methanol and a different portion of blotter stock should be used to remove the excess stain.

Abstract

This invention relates to a rapid process for determining groundwood pulp derived from waste paper. The process comprises (a) preparing a pulp from recycle furnish to form secondary papermaking fiber; and (b) preparing an absorbent sheet from said secondary papermaking fiber, characterizing the initial color of the absorbent sheet and staining the absorbent sheet with a phloroglucinol stain, characterizing the color of the absorbent sheet and comparing the color of the stained sheet with the initial color and selecting a target paper product based on the comparison.
The process also comprises determining CIE, L*, a*, b* and brightness values. The delta L*, a*, b* and brightness values are used to produce products having commercially acceptable properties.

Description

    CLAIM FOR PRIORITY
  • This non-provisional application claims the benefit of the filing date and is identical to U.S. Provisional Patent Application Serial No. 60/377,068, of the same title, filed May 1, 2002.[0001]
  • BACKGROUND FIELD OF INVENTION AND PRIOR ART
  • This application relates to recycling waste paper. Before waste paper can be reused, it is subject to pulping, deinking and bleaching processes. The cost of the waste paper and bleaching processes constitute a major part of the cost of the manufacturing cost for the production of paper products. Prior art methods controlled deinking and bleaching based upon the brightness of the incoming fiber with the attempt being made to deink and then bleach to a target brightness level. [0002]
  • This approach is not very successful with waste paper grades containing substantial amounts of groundwood fiber, also known as high lignin containing fiber. In recent years, waste paper costs have increased and the availability of low lignin waste paper has decreased. Thus, to continue economic operations of the large mills, the relatively plentiful high lignin containing waste paper and pulp feedstock has to be employed, especially with respect to economy or away-from-home tissue and towel products. [0003]
  • We have discovered a spectrophotometric and staining process which can be utilized in a short period of time, usually less than ten minutes in a commercial setting to enable us to evaluate what deinking and bleaching process to employ on the pulp. It should be noted that our process does not register colorless chemically treated fibers as groundwood. This is one shortcoming of the commonly used TAPPI Method T236-OM-99 for determining kappa numbers. The TAPPI Method does not distinguish between untreated and treated lignin in fibers and therefore forces the use of excess chemical treatment for pulp which is suitable for the manufacture of absorbent paper products. This is particularly problematic since bleached-chemithermomechanical pulp (BCTMP) constitutes a significant part of the recycle fiber supply. The TAPPI Method also takes more than twice as long as the process claimed herein to determine the amount of groundwood in the pulp. The TAPPI Method is therefore impractical for use in large scale paper making operations. [0004]
  • Illustrating the state-of-the-art are RE36,424 to Clement; U.S. Pat. No. 4,780,179 to Clement; U.S. Pat. No. 5,562,802 to Wang; U.S. Pat. No. 5,755,926 to Hankin et al.; U.S. Pat. No. 6,001,593 to Tourbollet et al. and U.S. Pat. No. 6,019,872 to Kurle. [0005]
  • SUMMARY OF THE INVENTION
  • We have discovered a process for increasing the amount of readily available and inexpensive high lignin containing waste paper which can be used in the manufacture of paper products exhibiting a targeted GE brightness number. Our process comprises staining handsheets of incoming pulp from waste paper with phloroglucinol and then measuring the color value of the stained handsheet using conventional MacBeth Spectrophotometer to provide CIE L*, a* and b* color measurements and brightness numbers. We have discovered a process for the manufacture of absorbent paper sheets from pulp derived from waste paper. This process comprises preparing a pulp from recycle furnish to form secondary fiber and preparing an absorbent sheet from said secondary papermaking fiber, characterizing the initial color of said absorbent sheet, staining said absorbent sheet with a phloroglucinol stain and characterizing the color of said absorbent sheet. The process depends on comparing the color of the stained sheet with initial color and selecting a target paper product based on the comparison. Advantageously the characterization comprises a parameter selected consisting of a lightness parameter, a red green parameter and a yellow blue parameter. [0006]
  • Suitably CIE L*, a*, b* and brightness values are used to determine the percent groundwood in the feedstock. This is done by obtaining delta L*, a*, b* and brightness values as shown in FIGS. [0007] 1-3, 12-15 and 19-20.
  • We have discovered that delta a*, delta b*, delta L* and delta brightness values are suitable in determining untreated groundwood content in the sheet and thus the suitability of the pulp for predetermined commercial applications. Suitable delta a* range is 0-20, delta L* range is 0 to 28, delta b* range is −2 to 17 and delta brightness range is 5 to 21 to produce 60 to 85 GE brightness pulp. [0008]
  • As stated above, we have discovered that unbleached groundwood content (high lignin containing fiber) correlates very closely with the change in the delta a*, delta b*, delta L* and delta brightness value using the spectrophotometer before and after staining of the handsheets. A delta a* value of less than 10, 10-20 and over 20 provide guidance as to the bleaching and deinking process to employ to obtain paper products exhibiting GE brightness values of 60 to 85. For example, when the delta a* value is 20 or above, the optimum use of the pulp is as unbleached brown stock or semi-bleached stock (having a GE brightness of about 40). When the unbleached groundwood content of the incoming pulp is very low, having a delta a* of 10 or less then a conventional hypochlorite bleaching process is used to produce 60 to 85 GE brightness paper products. When the unbleached groundwood content of the incoming pulp has a delta a* of about 10-20, then a non-delignified bleaching process is used to produce a 60 to 85 GE brightness paper product. The following Table 1 provides the approximate bleaching process selection based on delta a*, delta b*, delta L*, and delta brightness values: [0009]
    TABLE 1
    Bleaching Process Selection Based on delta
    a*, delta b*, delta L*, and delta brightness
    Bleaching Process delta a* delta b* delta L* delta brightness
    Conventional Hypo <10 <7 <14 <21
    Non-delignified 10-20 7-17 14-28 21-31
    Semi-bleaching >20 >17 >28 >31
  • Another aspect of our invention is to control the bleaching of unbleached fibers to maintain the pulp fed to a deinking and bleaching process within the targeted range to achieve the predetermined brightness levels of the paper products. [0010]
  • In either application or in a combination of both applications, the primary advantage of our process is the speed with which the delta a*, delta b*, delta L* and delta brightness results can be obtained, usually in ten minutes or less, 5-7 minutes being the normal range. The spectrophotometric and staining process of this invention is able to distinguish between modified and unmodified lignins. TAPPI Method T236-OM-99 lumps useful BCTMP lignins with unmodified lignins thus causing higher processing costs. In addition, the aforementioned TAPPI Method requires twenty minutes to be carried out while our process can be carried out in 5 to 10 minutes. [0011]
  • It should be noted that the BCTMP processes shift the spectral response into the invisible region making their use acceptable without additional bleaching to produce paper products having commercially acceptable brightness values. [0012]
  • In Table 2 the relationship between percent groundwood and delta a*, b*, L* brightness are set forth. [0013]
    TABLE 2
    Relationship Between Percent Groundwood and delta a*, b*, L* brightness
    % Delta
    Gmdwd Kappa Kappa L* a* b* Brightness Delta L* Delta a* Delta b* Brightness
    0 0.4 0.4 94.82 −0.44 6.24 79.25 1.23 0.48 −2.08 5.52
    0 0.4 94.66 −0.50 6.07 79.04 1.47 0.47 −2.09 6.15
    10 14.9 15.3 71.78 14.81 −5.24 47.76 21.97 15.88 13.43 26.97
    10 15.7 15.3 73.34 14.13 −4.76 49.86 20.64 15.41 12.91 25.43
    20 28.1 28.1 63.29 19.60 −7.26 37.00 28.86 20.55 17.56 32.00
    20 28.1 64.06 19.40 −7.35 38.13 28.23 20.47 17.62 31.19
    30 42.2 42.2 59.39 22.03 −8.73 33.02 31.36 22.53 19.12 33.09
    30 42.2 60.48 21.94 −8.79 34.43 31.04 22.78 18.50 34.00
    40 55.7 55.7 55.15 24.68 −9.57 28.53 35.11 25.22 20.64 35.93
    40 55.7 56.68 24.13 −9.84 30.50 34.05 24.86 20.34 35.50
    50 69.6 70.15 52.44 26.43 −10.17 25.94 36.84 26.82 22.11 35.73
    50 70.7 70.15 54.37 26.21 −10.48 28.29 35.21 26.78 22.25 34.14
    60 84.2 84.2 50.05 28.10 −10.56 23.72 38.69 28.49 22.86 36.59
    60 84.2 51.45 27.49 −10.85 25.34 37.98 28.19 22.73 36.71
    70 103.9 103.9 48.29 29.25 −10.91 22.18 40.07 29.59 23.32 37.34
    70 103.9 48.93 29.36 −11.07 22.90 39.29 29.83 23.63 36.24
    80 124 124 46.48 30.72 −10.95 20.50 41.01 30.98 23.52 37.29
    80 124 47.40 30.30 −11.39 21.60 40.42 30.74 24.06 36.70
    90 137 137 44.33 31.88 −11.18 18.74 43.53 32.74 23.68 39.80
    90 137 45.17 31.66 −11.58 19.66 42.89 32.50 24.14 39.20
    100 150.2 153.05 41.45 33.61 −11.20 16.35 40.03 34.15 25.12 38.39
    100 155.9 153.05 42.86 32.96 −11.69 17.74 44.77 33.92 26.22 38.38
  • The TAPPI Method T236-OM-99 measures only gross lignin content and thus under predicts brightness attainable with the pulp stream containing modified lignins. Thus, if the aforementioned TAPPI Method of determining lignin content is used to control the amount of the higher grade waste papers added to the waste paper stream, more expensive higher grades will be used than is necessary to achieve the targeted brightness of the paper products. Our process avoids this costly waste as the amount of high grade waste paper required to reach the targeted brightness is predicted more accurately and the bias toward mixing in too much high grade waste paper can be substantially reduced. [0014]
  • A very important aspect of our invention is that it enables a more precise control of finished stock brightness. Our process predicts the finished product more accurately and therefore will usually result in less variation of the finished stock brightness and higher usage of the groundwood containing waste paper to meet the same target brightness. Thus, resulting in greater savings and also facilitating the use of waste paper which may not have been used to produce paper products having GE brightness values of 60 to 85.[0015]
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 is a graph illustrating the relationship between delta a* values and percent groundwood. [0016]
  • FIG. 2 is a graph illustrating the relationship between a* and percent groundwood. [0017]
  • FIG. 3 is a graph illustrating the relationship between the estimated percent groundwood and delta a*. [0018]
  • FIG. 4 is a graph illustrating the relationship between a* and reaction time. This graph demonstrates that a* value for handsheets can be obtained within five minutes after the handsheet is treated with phloroglucinol. [0019]
  • FIG. 5 is a graph illustrating the relationship between delta a* and kappa numbers obtained using TAPPI Method T236-OM-99. [0020]
  • FIG. 6 is a graph illustrating the relationship between kappa numbers and percent total groundwood using TAPPI Method T236-OM-99. [0021]
  • FIG. 7 is a graph illustrating the relationship between delta a* and kappa number. It should be noted that TAPPI Method T236-OM-99 includes in kappa numbers BCTMP treated groundwood fibers while the delta a* excludes these fibers and other fibers which have been chemically treated. [0022]
  • FIGS. 8 and 9 are graphs showing the relationship between the kappa number and percent of total groundwood. [0023]
  • FIG. 10 is a graph illustrating the relationship between a* and kappa numbers obtained by using TAPPI Method T236-OM-99. [0024]
  • FIG. 11 is a graph illustrating the relationship between delta b* and kappa numbers obtained by using TAPPI method T236-OM-99. [0025]
  • FIG. 12 is a graph illustrating delta b* versus percent groundwood. [0026]
  • FIG. 13 is a graph illustrating b* versus percent groundwood. [0027]
  • FIG. 14 is a graph illustrating the relationship between b* and Kappa numbers obtained by using TAPPI Method T236-OM-99. [0028]
  • FIG. 15 is a graph which illustrates the relationship between delta L* and percent groundwood. [0029]
  • FIG. 16 is a graph illustrating L* versus percent groundwood. [0030]
  • FIG. 17 is a graph illustrating the relationship between delta L* and Kappa numbers obtained by using TAPPI Method T236-OM-99. [0031]
  • FIG. 18 is a graph illustrating the relationship between L* and Kappa number obtained by using TAPPI Method T236-OM-99. [0032]
  • FIG. 19 is a graph illustrating delta brightness and percent groundwood. [0033]
  • FIG. 20 is a graph illustrating brightness and percent groundwood. [0034]
  • FIG. 21 is a graph illustrating the relationship between delta brightness and Kappa numbers obtained by using TAPPI Method T236-OM-99; [0035]
  • FIG. 22 is a graph illustrating the relationship between brightness and Kappa numbers obtained by using TAPPI Method T236-OM-99; [0036]
  • FIG. 23 is a graph illustrating transformed brightness versus percent groundwood. [0037]
  • FIG. 24 is a graph illustrating normalized derivatives of L*, a*, b*, brightness, delta L*, delta a*, delta b* and delta brightness*. [0038]
  • FIG. 25 is a secondary fiber plant flow diagram. [0039]
  • FIG. 26 is a graph illustrating the relationship between delta a* and the kappa number.[0040]
  • DESCRIPTION OF THE INVENTION
  • In recent years, the cost of waste paper has escalated. There is limited availability for good quality waste paper. The present invention answers a long felt need for utilizing waste paper having high lignin or groundwood content. It also was determined that TAPPI Method T236-OM-99 fails to recognize that modified lignins such as those created by the BCTMP processes do not need the rigorous deinking and bleaching regiments required of waste paper pulp having high groundwood content. The TAPPI Method also takes about 20 minutes for determining the amount of groundwood in waste paper pulp while in our process this is done in less than 10 minutes, usually 5 to 7 minutes. The claimed process overcomes all these disadvantages of the prior art groundwood determination methods and provides a fast and reliable method for determining the amount of chemically untreated groundwood fiber present in the pulp being charged to the deinking and bleaching system. [0041]
  • We have discovered a process for the manufacture of absorbent paper sheets from pulp derived from waste paper. This process comprises preparing a pulp from recycle furnish to form secondary fiber and preparing an absorbent sheet from said secondary papermaking fiber, characterizing the initial color of said absorbent sheet with a phloroglucinol stain and characterizing the color of said absorbent sheet. The process depends on comparing the color of the stained sheet with the initial color and selecting a target paper product based on the comparison. Suitably the characterization comprises a parameter selected consisting of lightness parameter, a red green parameter and a yellow blue parameter. [0042]
  • Suitable CIE L*, a*, b* and brightness values are used to determine the percent groundwood in the feedstock. This is done by obtaining the delta L*, a*, b* and brightness values. [0043]
  • The delta a values versus percent groundwood are illustrated in FIGS. 1 and 3. The relationship between delta* and Kappa number is shown in FIG. 5. It should be noted that Kappa numbers using TAPPI Method T236-OM-99 give a higher groundwood content since that method cannot distinguish between chemically treated or untreated groundwood. The Kappa number is defined as follows in TAPPI Method T236-OM-99P: [0044]
  • The Kappa number is the volume (in millimeters) of 0.1N potassium permanganate solution consumed by one gram of moisture-free pulp the results are corrected to 50% consumption of the permanganate added. [0045]
  • It should be noted that L*, a* and b* and brightness parameters are suitably measured using TAPPI Method T-524-OM-94. These are called Hunter color values. In the Hunter Color Scheme L, a and b designate color as follows: [0046]
  • L denotes lightness increasing from 0 for black to 100 for perfect white, a shows redness when plus, green when minus and zero for grey, b represents yellowness when plus, blueness when minus and zero when grey. [0047]
  • The delta b* values versus percent groundwood are illustrated in FIG. 12. To obtain GE brightness values in the paper product of about 60 to 85 the delta b* values should be in the range of about −2 to 17. [0048]
  • The delta L* values versus percent groundwood are illustrated in FIG. 15. To obtain GE brightness values in the paper product of about 60 to 85 the delta L* values should be about 0 to 28. [0049]
  • The delta brightness values versus percent groundwood are illustrated in FIG. 19. To obtain GE brightness values in the paper product of about 60 to 85 the delta brightness value should be about 5 to 21. [0050]
  • Our invention provides a rapid process for determining chemically untreated groundwood in pulp derived from waste paper prior to it being charged to the deinking/bleaching system. In our process handsheets are made from the pulp undergoing evaluation and staining these handsheets with phloroglucinol stain This solution consists of 8.0 grams phloroglucinol, dihydrate, 100 ml ethyl alcohol and 100 ml concentrated hydrochloric acid. Gretag MacBeth Color Eye 3100 spectrophotometer is used to measure the color value of the stained handsheet sample and compare it to unstained handsheet sample. The MacBeth spectrophotometer is calibrated to provide CIE L*, a* and b* measurements. We have discovered that chemically untreated groundwood content correlates very closely to the change or delta in the a*, L* and b* values obtained using the spectrophotometer before and after staining with phloroglucinol. In FIG. 4 the graph shows the relationship between a* and reaction time. From FIG. 4 it can be determined that reliable delta a* values can be obtained within five minutes after staining with phloroglucinol. [0051]
  • FIGS. 1 and 3 illustrate the correlation between percent chemically untreated groundwood and delta a*. Those values are very important to the paper manufacturer since if the delta a* value is less than 10 then conventional hypobleaching processes may be used to produce 60 to 85 GE brightness paper products. If the unbleached groundwood content incoming pulps is in the medium range as indicated by an average delta a* of 10 to 20, then a non-delignified bleaching technique, such as peroxide and/or hydrosulfide bleaching processes may be used to produce the 60 to 85 GE brightness paper products. If the unbleached groundwood content in the incoming pulp is in the high range as indicated by a delta a* value of greater than about 20, then the pulp can be used for semi-bleached or unbleached stock generally known as brown stock. This same relationship holds for specific delta b*, delta L* and delta brightness values. By utilizing the phloroglucinol staining process and spectrophotometer analysis of the treated and untreated handsheets we obtain delta a*, b*, L* and brightness values which give us control on what deinking/bleaching process to utilize. This, of course, depends on the amount of chemically untreated groundwood in the incoming pulp. Alternatively, we can use this same information to blend pulps to maximize the amount of groundwood utilized to achieve a paper product having commercially acceptable brightness properties. 60 to 85 GE brightness pulps are used to produce absorbent paper products such as tissues. [0052]
  • Our invention includes a process for utilizing chemically treated groundwood in addition to untreated groundwood. Since our delta values do not include chemically treated groundwood or groundwood which is derived from BCTMP treated waste paper. Thus, using TAPPI Method T236-OM-99, the kappa values for groundwood obtained in FIGS. 5, 7 and [0053] 8 overstate the amount of groundwood in the pulp since the chemically treated and BCTMP derived groundwood is reported as untreated groundwood. This reporting error results in the use of a more expensive wastepaper and deinking/bleaching process than would be required if our claimed process would be utilized to produce paper products exhibiting commercially acceptable brightness. These values usually are a 60 to 85 GE brightness value.
  • FIG. 25 shows the operation of the secondary fiber plant flow diagram. [0054] Waste paper 100 is fed to pulper 101 and charged to drop tanks 1 (102), 2 (103) and 3 (104). The ratio of the pulps from the three drop tanks is combined into the blend chest 106. The delta a* or alternatively the delta L* or delta b* or delta brightness testing is conducted on samples coming from the blend chest at point 107. After the delta a* or alternatively delta L* or delta b* or delta brightness values are obtained, the deinking system 108 is adjusted for the severity of ink removal treatment. Similarly, the severity of the bleaching system 109 is adjusted. The deinked and bleached pulp is stored in the finished stock tank 110 from which it is fed into the paper making machines.
  • The relationship between delta a* and percent groundwood as shown in FIG. 6 was an exponential curve for 0 percent to 30 percent groundwood range and a straight line for greater than 50 percent groundwood. A possible explanation of this shape was that MacBeth spectrophotometer mainly measures the color intensity of the surface of phloroglucinol-stained handsheet. The rapid color development may be assigned principally to the fast reaction between the phloroglucinol and the reactive lignin in the surface of the handsheet. Once most of the reactive lignin in the surface of the handsheet is saturated with phloroglucinol, the reaction slows down quickly and the relationship between color intensity and groundwood content follows a linear function with a much lower slope than the initial stage. This surface phenomena of the staining method may provide a better prediction of bleachability of the groundwood containing pulp than other lignin determination methods. [0055]
  • In one experiment the regular unbleached pulp had the delta a* ranged from 11 to 19 and averaged 13.5 in one deinking process. This corresponds to a groundwood fiber content of 5% to 20%, averaging about 8%. In the trial an improvement was made to control the pulp from the [0056] blend chest 106 having a delta a* value in the range of 16-18, and still maintained the same finished product brightness.
  • This corresponded to an increase in groundwood for fiber usage from 8% to about 15%. [0057]
  • It was observed that existing operations in one facility had a groundwood content of 4% to 13% in the wastepaper furmish. For reasons of economy and raw material utilization the groundwood content should be increased to about 15-20% when the deinked pulp from [0058] 108 is fed into the bleaching system 109 using Eopy bleach processes. This corresponds to a delta a* value of 16-18.
  • In another run the groundwood in waste paper was increased to 17-25%. Thus, previously discarded waste paper could be utilized. At these higher groundwood levels still commercially preferred GE brightness targets of greater than 60 were met. [0059]
  • The following is the procedure for the rapid determination of groundwood in handsheets: [0060]
  • Apparatus/Materials: [0061]
  • Drying Fan and Sample Stand, available from: [0062]
  • Georgia-Pacific [0063]
  • Neenah Technical Center [0064]
  • 920-729-8496 [0065]
  • Gretag MacBeth Color Eye 3100 Spectrophotometer Settings: [0066]
  • Reflectance [0067]
  • Spectral Component Excluded [0068]
  • UV Component Excluded [0069]
  • Large Area View [0070]
  • Measurements with white body [0071]
  • [0072] Glass Plate 5″×5″×¼″
  • Timer [0073]
  • 1 Kg weight [0074]
  • Blotter Stock (Pulp Testing Paper), 8″×8″[0075]
  • Methanol [0076]
  • Phloroglucinol Stain Solution [0077]
  • 8.0 g Phloroglucinol, Dihydrate [0078]
  • 100 ml Ethyl Alcohol [0079]
  • 20 ml Concentrated Hydrochloric Acid [0080]
  • Notes: [0081]
  • Light sensitive, store in amber bottle. [0082]
  • Solution good for 2 months if protected from light and kept in a sealed container. [0083]
  • Use extreme caution when using concentrated Hydrochloric Acid. [0084]
  • Specimen Preparation: [0085]
  • A 2 g Handsheet was used for testing [0086]
  • Procedure: [0087]
  • 1. Calibrate the MacBeth 3100. [0088]
  • 2. Place the handsheet over the sample port holding it in place with the white body [0089]
  • 3. Take an initial color reading, recording the a* value. [0090]
  • 4. Set the timer for 5 minutes. [0091]
  • 5. Place the handsheet on the glass plate. [0092]
  • 6. Dispense 0.30 ml of the Phloroglucinol Stain Solution to the handsheet about 2 inches from its edge. [0093]
  • 7. Start the timer. [0094]
  • 8. Let the stain spread on the handsheet for 30 seconds. (Note: A 1.5″ diameter stain is needed to take the final a* reading.) [0095]
  • 9. Place the handsheet between two pieces of blotter stock and press on the stained area with the 1-Kg weight for 5-10 seconds to remove excess stain. [0096]
  • 10. Remove the handsheet from between the blotter stock and hang it from the clip that is on the front of the drying fan. The stained side should face the fan. [0097]
  • 11. After the 5 minutes is up, take a final a* reading of the stained area being sure that the stained portion of the handsheet covers the entire sample port. [0098]
  • 12. the delta a* can be obtained by subtracting initial a* from the final a* reading. [0099]
  • 13. For additional repeats the sample glass should be cleaned with methanol and a different portion of blotter stock should be used to remove the excess stain. [0100]
  • The estimated percent groundwood vs. delta a* is set forth in FIG. 3 and the formula derived from FIG. 3 shows that percent groundwood=(0.8383+0.0504 delta a*)[0101] 5.
  • Modifications to specific features illustrated above within the spirit and scope of the present invention, set forth in the appended claims, will be readily apparent to those of skill in the art. [0102]

Claims (53)

What is claimed is:
1. A process for the manufacture of absorbent paper sheets from pulp derived from waste paper said process comprising:
(a) preparing a pulp from recycle furnish to form secondary papermaking fiber;
(b) preparing an absorbent sheet from said secondary papermaking fiber;
(c) characterizing the initial color of said absorbent sheet;
(d) staining said absorbent sheet with a phloroglucinol stain;
(e) characterizing the color of said absorbent sheet; and
(f) comparing the color of said stained sheet with initial color and selecting a target paper product based on the comparison
2. The process of claim 1, wherein the characterization comprising a parameter selected consisting of a lightness parameter, a red green parameter and yellow blue parameter.
3. The process of claim 1, wherein the groundwood percent range is preselected.
4. The process of claim 1, said process comprising conducting a spectrophotometric analysis of absorbent sheets made from waste paper feedstock before and after treatment of the sheets with phloroglucinol, the spectral analysis including CIE a* color measurements and determining delta a* values between the untreated and treated sheets and using the delta a* value to select deinking and bleaching processes.
5. The process of claim 1, said process comprising conducting a spectrophotometric analysis of absorbent sheets made from waste paper feedstock before and after treatment of the sheets with phloroglucinol, the spectral analysis including CIE L* color measurements and determining delta L* values between the untreated and treated sheets and using the delta L* value to select deinking and bleaching processes.
6. The process of claim 1, said process comprising conducting a spectrophotometric analysis of absorbent sheets made from waste paper feedstock before and after treatment of the sheets with phloroglucinol, the spectral analysis including CIE b* color measurements and determining delta b* values between the untreated and treated sheets and using the delta b* value to select deinking and bleaching processes.
7. The process of claim 1, said process comprising conducting a spectrophotmetric analysis of absorbent sheets made from waste paper feedstock before and after treatment of the sheets with phloroglucinol, the spectral analysis including CIE brightness measurements determining the delta brightness values to select deinking and bleaching processes.
8. The process of claim 4, wherein the delta a* values are about 0 to 20.
9. The process of claim 5, wherein the delta L* values are about 0 to 28.
10. The process of claim 6, wherein the delta b* values are about −2 to 17.
11. The process of claim 7, wherein the delta brightness values are about 5 to 21.
12. A method of making absorbent sheet from recycle furnish comprising:
(a) pulping waste paper to form papermaking fiber;
(b) preparing an absorbent sheet from said secondary papermaking fiber;
(c) characterizing said absorbent sheet by way of analytical technique comprising applying a phloroglucinol thereto and determining the color thereof; and
(d) based upon the characterization of step (c) selecting a target product for said secondary papermaking fiber.
13. A process for increasing the amount of inexpensive high lignin containing waste paper used as feedstock in the manufacture of paper products exhibiting GE brightness value of about 60 to 85, said process comprising conducting a spectrophotometric analysis of handsheets made from waste paper feedstock before and after treatment of the handsheets with phloroglucinol, the spectral analysis including CIE a* color measurement and determining delta a* values between the untreated and treated handsheets and using the delta a* values to select deinking and bleaching processes and controlling the amount of high lignin fiber feedstock which is to be utilized to produce absorbent paper products exhibiting GE brightness of about 60 to 85.
14. The process of claim 13, wherein the delta a* values between untreated and treated handsheets are determined in less than 10 minutes.
15. The process of claim 13, wherein the delta a* is less than 20.
16. The process of claim 15, wherein the delta a* is between 10 and 20.
17. The process of claim 15, wherein the delta a* is less than 10.
18. The process of claim 13, wherein the GE brightness value is about 60 to 85.
19. A process for tailor blending high lignin waste paper pulp with other waste paper pulp to produce paper products having predetermined commercially acceptable brightness properties comprising conducting a spectrophotometric analysis of handsheets from pulps derived from various waste paper sources before and after treatment with phloroglucinol, the spectral analysis including CIE a* color measurements and determining the delta a* values of the untreated and treated handsheets and using the delta a* values in blending the combination of waste paper pulp for appropriate deinking and bleaching treatment and to produce paper having the desired brightness while including the maximum amount of the low cost high lignin containing groundwood fiber.
20. The process of claim 19, wherein the groundwood fiber comprises substantial amounts of bleached chemithermochemical pulp (BCTMP) fiber.
21. The process of claim 13 or claim 19 wherein the delta a* values obtained determine the bleaching and deinking process used.
22. The process of claim 21, when delta a* values exceed 20, the pulp is deinked but unbleached or semibleached.
23. The process of claim 21, when the delta a* values are in the range of about 10 to 20, a peroxide, hydrosulfide or a combination of both processes are used to deink and bleach the pulp to produce feedstock for the manufacture of paper products which exhibit a GE brightness of at least 60.
24. The process of claim 23, wherein the paper products exhibit a GE brightness of about 65-80.
25. The process of claim 21, when the delta a* values are 10 or below, a hypo deinking bleaching process is used to produce feedstock for the manufacture of paper products exhibiting a GE brightness of at least 60.
26. The process of claim 25, wherein the paper products exhibiting a GE brightness of about 65 to 80.
27. An economical high speed process for increasing the amount of inexpensive and readily available high lignin containing waste paper used in the manufacture of paper products exhibiting commercially acceptable brightness, said process comprising conducting in less than ten minutes a spectrophotometric analysis of handsheets from waste paper pulp before and after treatment of the handsheets with phloroglucinol, the spectrophotometric analysis including CIE a* color measurement and determining the delta a* values between the untreated and treated handsheets and using the delta a* values to select the deinking and bleaching process and controlling the amount of high lignin fiber feedstock which can be utilized to produce paper products having predetermined commercially acceptable brightness properties.
28. The process of claim 27, wherein the delta a* values obtained determine the bleaching and deinking process.
29. The process of claim 28, when delta a* values are in the range of about 10 to 20, a peroxide, hydrosulfide or a combination of both processes are used to deink and bleach the pulp to produce feedstock for the manufacture of paper products having acceptable brightness.
30. The process of claim 29, when the delta a* values are 10 or below a hypo deinking bleaching process is used to produce feedstock for the manufacture of paper products having commercially acceptable brightness.
31. The process of claim 27, wherein the delta a* values are obtained within 7 minutes.
32. A rapid process for determining groundwood in pulp derived from waste paper, said process comprising conducting a spectrophotometric analysis of handsheets made from said pulp before and after treatment of the handsheets with phloroglucinol, the spectral analysis including CIE a* color measurements and determining delta a* values between the untreated and treated handsheets.
33. The process of claim 32, wherein delta a* values below 10 indicate that the pulp is of very high quality.
34. The process of claim 32, wherein the delta a* values of 10-20 indicate that the pulp is suitable for production of paper products exhibiting a GE brightness value of at least 76.
35. The process of claim 32, wherein the delta a* values in excess of 20 indicate that the paper products produced should be unbleached stock, known as brown stock, or semi-bleached stock.
36. The process of claim 32, wherein bleached chemithermal mechanical pulp (BCTMP) fibers are not analyzed as untreated groundwood and included in delta a* values.
37. The process of claim 32, wherein the delta a* values are determined within 10 minutes.
38. The process of claim 37, wherein the delta a* values are determined in about 5 to 7 minutes.
39. An economical high speed process for increasing the amount of inexpensive and high lignin containing waste paper used in the manufacture of paper products exhibiting commercially acceptable brightness, said process comprising conducting in less than ten minutes a spectrophotometric analysis of handsheets from waste paper pulp before and after treatment of the handsheets with phloroglucinol, the spectrophotometric analysis including CIE L* color measurements and determining the delta L* values between the untreated and treated handsheets and using the delta L* values to select the deinking and bleaching process and controlling the amount of high lignin fiber feedstock which can be utilized to produce paper products having predetermined commercially acceptable brightness properties.
40. An economical high speed process for increasing the amount of inexpensive and high lignin containing waste paper used in the manufacture of paper products exhibiting commercially acceptable brightness, said process comprising conducting in less than ten minutes a spectrophotometric analysis of handsheets from waste paper pulp before and after treatment of the handsheets with phloroglucinol, the spectrophotometric analysis including CIE b* color measurements and determining the delta b* values between the untreated and treated handsheets and using the delta b* values to select the deinking and bleaching process and controlling the amount of high lignin fiber feedstock which can be utilized to produce paper products having predetermined commercially acceptable brightness properties.
41. The process of claim 39, wherein the delta L* values are about 0 to 28.
42. The process of claim 40, wherein the delta b* values are about −2 to 17.
43. An economical high speed process for increasing the amount of inexpensive high lignin containing waste paper used in the manufacture of paper products exhibiting commercially acceptable brightness, said process comprising conducing in less than ten minutes a spectrophotometric analysis of handsheets from waste paper pulp before and after treatment of the handsheets with phloroglucinol the spectrophotometric analysis including CIE brightness measurements and determining the delta brightness values between the untreated and treated handsheets and using the delta brightness values to select the deinking and bleaching process and controlling the amount of high lignin fiber feedstock which can be utilizing to produce paper products having predetermined commercially acceptable brightness properties.
44. The process of claim 43, wherein the delta brightness values are about 5 to 21.
45. The process of claim 2, wherein the groundwood percent range is preselected.
46. The process of claim 2, said process comprising conducting a spectrophotometric analysis of absorbent sheets made from waste paper feedstock before and after treatment of the sheets with phloroglucinol, the spectral analysis including CIE a* color measurements and determining delta a* values between the untreated and treated sheets and using the delta a* value to select deinking and bleaching processes.
47. The process of claim 2, said process comprising conducting a spectrophotometric analysis of absorbent sheets made from waste paper feedstock before and after treatment of the sheets with phloroglucinol, the spectral analysis including CIE L* color measurements and determining delta L* values between the untreated and treated sheets and using the delta L* value to select deinking and bleaching processes.
48. The process of claim 2, said process comprising conducting a spectrophotometric analysis of absorbent sheets made from waste paper feedstock before and after treatment of the sheets with phloroglucinol, the spectral analysis including CIE b* color measurements and determining delta b* values between the untreated and treated sheets and using the delta b* value to select deinking and bleaching processes.
49. The process of claim 2, said process comprising conducting a spectrophotometric analysis of absorbent sheets made from waste paper feedstock before and after treatment of the sheets with phloroglucinol, the spectral analysis including CIE brightness measurements determining the delta brightness values to select deinking and bleaching processes.
50. The process of claim 46, wherein the delta a* values are about 0 to 20.
51. The process of claim 47, wherein the delta L* values are about 0 to 28.
52. The process of claim 48, wherein the delta b* values are about −2 to 17.
53. The process of claim 49, wherein the delta brightness values are about 5 to 21.
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