AU2020100238A4 - Process for preparing paper-based material by ultrasonic-assisted ionic liquid treatment of ecf bleached kraft pulp - Google Patents
Process for preparing paper-based material by ultrasonic-assisted ionic liquid treatment of ecf bleached kraft pulp Download PDFInfo
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP 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
- D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
- D21H11/02—Chemical or chemomechanical or chemothermomechanical pulp
- D21H11/04—Kraft or sulfate pulp
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
- B01J19/10—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing sonic or ultrasonic vibrations
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-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
- D21C9/001—Modification of pulp properties
- D21C9/002—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives
- D21C9/005—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives organic compounds
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-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
- D21C9/001—Modification of pulp properties
- D21C9/007—Modification of pulp properties by mechanical or physical means
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-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
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/1005—Pretreatment of the pulp, e.g. degassing the pulp
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C3/00—Pulping cellulose-containing materials
- D21C3/02—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes
- D21C3/022—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes in presence of S-containing compounds
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C3/00—Pulping cellulose-containing materials
- D21C3/22—Other features of pulping processes
- D21C3/26—Multistage processes
- D21C3/266—Multistage processes the same pulping agent being used in all stages
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-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
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/1057—Multistage, with compounds cited in more than one sub-group D21C9/10, D21C9/12, D21C9/16
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-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
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/12—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds
- D21C9/14—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds with ClO2 or chlorites
- D21C9/144—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds with ClO2 or chlorites with ClO2/Cl2 and other bleaching agents in a multistage process
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-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
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/147—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-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
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/16—Bleaching ; Apparatus therefor with per compounds
- D21C9/163—Bleaching ; Apparatus therefor with per compounds with peroxides
Abstract
The present invention discloses a process for preparing a paper-based material by ultrasonic assisted ionic liquid treatment of ECF bleached kraft pulp, where ultrasonic-assisted ionic liquid pretreatment is performed on an unbleached kraft pulp, then the obtained kraft pulp is subjected to ECF bleaching. In view of a problem about low physical strength of bleached pulp caused by serious fiber degradation due to poor selectivity of oxygen delignification during the bleaching process, the present invention presents a process for ultrasonic-assisted ionic liquid pretreatment. In the process, physical cavitation of ultrasonic wave and chemical treatment effect of ionic liquid are used to loosen the pulp fiber structure to improve the swelling and fibrillation of the pulp fiber and allow an easy delignification during the bleaching process, thereby avoiding oxidative damage of fiber in the bleaching process. This can improve physical strength properties of hardwood paper-based materials as well as brightness thereof. P10311.AU Specification 18/02/2020
Description
PROCESS FOR PREPARING PAPER-BASED MATERIAL BY ULTRASONICASSISTED IONIC LIQUID TREATMENT OF ECF BLEACHED KRAFT PULP
TECHNICAL FIELD
The present invention relates to the technical field of papermaking, and in particular to a process for preparing a paper-based material by ultrasonic-assisted ionic liquid treatment of ECF bleached eucalyptus kraft pulp.
BACKGROUND
The descriptions herein merely provide background information related to the present disclosure and may not constitute the prior art.
The pulp and papermaking industry is one of the most important basic industries in China’s national economy, which has always played an important role in global industrial manufacturing industry. Levels of production and consumption of paper and paperboard have been a vital measure of economic development level and social progress in a country. Since 2012, China’s total output of paper and paperboard has exceeded 1/4 of the global output, ranking the first place in the world. At present, the global paper industry mainly depends on wood resources; among papermaking raw materials, wood fiber has reached a proportion of 94%, and particularly, the proportion of such hardwood as poplar and eucalyptus is gr a sequence owing in the pulp and paper industry. With the emphasis on sustainable cleaner production in papermaking technology, most of papermaking enterprises adopt clean delignification techniques, e.g., total chlorine free (TCF) and elemental chlorine free (ECF) bleaching techniques, thereby reducing the organic pollutant content of wastewater greatly. However, ECF bleaching is principally achieved by oxidation; in particular, the oxygen bleaching easily leads to degradation of carbohydrates, lowering the degree of polymerization of cellulose to influence physical properties of pulp paper, e.g., low tensile strength.
SUMMARY
To address the defects existing in the prior art, preferred embodiments of the present invention provide a process for preparing a paper-based material by ultrasonic-assisted ionic liquid treatment of ECF bleached eucalyptus kraft pulp. This process can improve the physical strength properties of finished paper made from bleached kraft pulp, as well as the brightness of 30 the bleached kraft pulp.
To achieve the above objective, the technical solution adopted by the present invention is:
P10311.AU Specification 18/02/2020
2020100238 27 Feb 2020
The first aspect of the present invention provides a process for preparing a paper-based material by ultrasonic-assisted ionic liquid treatment of ECF bleached kraft pulp, where the ultrasonic-assisted ionic liquid pretreatment is performed on an unbleached kraft pulp, then the obtained kraft pulp is subjected to ECF bleaching.
The ionic liquids are molten salts fully composed by cations and anions, which presents as liquid at room temperature, featuring good thermal stability, recyclability, non-volatility, and excellent solubility. Treatment of plant fibers with ionic liquid has effects on both crystallinity and crystalline form of cellulose, improves the swelling of fibers, increases specific surface areas thereof, and enhances the interaction between fibers. In addition, the ionic liquid may also allow selective separation of chemical components of lignocellulose, to improve the bleachability and enhance the physical strength of the fiber.
Ultrasonic treatment features low energy consumption, non-pollution, safety, and low cost. The high pressure and shock waves produced by ultrasonic cavitation act on the fiber surface to allow stress and strain concentration, leading to changes in interior fibrous structure, dislocating microcrystals, loosing fibers, increasing specific surface area, decreasing crystallinity, enlarging amorphous regions, enhancing interactions between fibers, and improving physical and optical properties of a pulp. Meanwhile, sonicated fibers exhibit good water retention value and accessibility. The ultrasonic-assisted ionic liquid treatment can modify both surface charge density and specific surface area of plant fibers, thereby improving the tensile, tear, and bursting strengths of the pulp.
The design concept of the present invention is as follows: In view of a problem about low physical strength of bleached pulp caused by serious fiber degradation due to poor selectivity of oxygen delignification during the bleaching process, the present invention presents a process for ultrasonic-assisted ionic liquid pretreatment. In the process, physical cavitation of ultrasonic 25 wave and chemical treatment effect of ionic liquid are used to loosen the pulp fiber structure to improve the swelling and fibrillation of the pulp fiber and allow an easy delignification during the bleaching process, thereby avoiding oxidative damage of fibers in the bleaching process. This can improve not only physical strength properties of hardwood paper-based materials, but also brightness thereof.
The second aspect of the present invention provides a paper-based material prepared by the preceding process. The paper-based material has an improved physical strength and brightness.
The beneficial effects of preferred embodiments of the present invention are as follows:
P10311.AU Specification 18/02/2020
2020100238 27 Feb 2020 (1) Through ultrasonic-assisted ionic liquid pretreatment, the present invention may enable the prepared paper-based material to have such advantages as high folding endurance, tensile strength, bursting strength, and tearing strength, which is suitable to prepare a plurality of types of paper-based materials.
(2) In the present invention, ionic liquid pretreatment may protect plant fibers, alleviates alkaline degradation thereof in the subsequent bleaching process, and improves pulp fiber quality; moreover, the ionic liquid used is structurally stable, non-volatile, recyclable, and environmentally friendly.
(3) The pretreatment of the present invention may improve the bleachability of hardwood pulp, lowers dosages of bleaching chemicals and agents, improves bleaching efficiency, and reduces pollution load.
(4) The treatment of the present invention can be simple, strongly practicable, and easy to generalize.
DETAILED DESCRIPTION
It should be noted that the following detailed description is exemplary and aims to further describe the present invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art.
It should be noted that the terms used herein are merely used for describing the specific embodiments, but is not intended to limit exemplary embodiments of the present invention. As used herein, the singular form is also intended to include the plural form unless otherwise indicated obviously from the context. Furthermore, it should be further understood that the terms includes and/or including used in this specification specify the presence of stated features, steps, operations, elements, components and/or their groups.
In view of the defect that ECF bleaching leads to a decrease in the degree of polymerization 25 of cellulose through oxidation bleaching and thus influences physical properties of pulp paper, and to solve the above technical problem, the disclosure presents a process for preparing a paperbased material by ultrasonic-assisted ionic liquid treatment of ECF bleached kraft pulp.
A typical embodiment of the present disclosure provides a process for preparing a paperbased material by ultrasonic-assisted ionic liquid treatment of ECF bleached kraft pulp, where 30 ultrasonic-assisted ionic liquid pretreatment is performed on an unbleached kraft pulp, then the obtained kraft pulp is subjected to ECF bleaching.
P10311.AU Specification 18/02/2020
2020100238 27 Feb 2020
The design concept of the present disclosure is as follows: In view of a problem about low physical strength of bleached pulp caused by serious fiber degradation due to poor selectivity of oxygen delignification during the bleaching process, embodiments of the present invention present a process for ultrasonic-assisted ionic liquid pretreatment. In the process, physical cavitation of ultrasonic wave and chemical treatment effect of ionic liquid are used to loosen the pulp fiber structure to improve the swelling and fibrillation of the pulp fiber and allow an easy delignification during the bleaching process, thereby avoiding oxidative damage of fiber in the bleaching process. This can improve not only the physical strength properties of hardwood paperbased materials, but also brightness thereof.
According to the inventive concept of the present disclosure, particularly, the ultrasonicassisted ionic liquid pretreatment is performed on a eucalyptus kraft pulp, followed by ECF bleaching during the bleaching process, and a pulp with good physical strength properties and brightness can be obtained.
In one or more examples of the implementation, the unbleached kraft pulp is a pulp obtained by kraft cooking of eucalyptus.
In one or more examples of the implementation, sonication time is 55 min.
In one or more examples of the implementation, a dosage of the ionic liquid is 9 wt%.
In one or more examples of the implementation, anions in the ionic liquid include any one of HSO4· or Cl ion, or a mixture thereof, and cations include any one of l-butyl-3methylimidazolium or triethylammonium ion, or a mixture thereof.
The l-butyl-3-methylimidazolium ion has the following structural formula:
N
N
The triethylammonium ion has the following structural formula:
Pl0311.AU Specification 18/02/2020
Η
2020100238 27 Feb 2020
In one or more examples of the implementation, a sequence of the ECF bleaching is OADiEopD2, including steps of: firstly, conducting a pretreated pulp on oxygen delignification (O stage), and washing the pulp after the O stage; then conducting acid treatment (A stage), and washing the pulp after the A stage; then conducting chlorine dioxide bleaching (Di stage), and washing the pulp after the Di stage; then conducting hydrogen peroxide bleaching (Eop stage), and washing the pulp after the Eop stage; then conducting chlorine dioxide bleaching (D2 stage), and washing the pulp after the D2 bleaching stage, to obtain a bleached pulp.
Detailed process conditions of the OADiEopD2 bleaching sequence include: oxygen delignification (O stage): 10% pulp consistency, 3 wt% NaOH, 0.6% MgSCU, at a temperature of 100 °C for 60 min under oxygen pressure of 0.5 MPa; acid treatment (A stage): at a pH of 3.5 to
4.5 for 120 min; chlorine dioxide bleaching (Di stage): 0.7 wt% chlorine dioxide, 10 wt% pulp consistency, at a pH of 2 to 3 and a temperature of 70 °C for 30 min; hydrogen peroxide bleaching (Eop stage): 1 wt% hydrogen peroxide, 10 wt% pulp consistency, at a pH of 11 to 12 and a temperature of 90 °C for 60 min under oxygen pressure of 0.4 MPa; chlorine dioxide bleaching (D2 stage): 0.8 wt% chlorine dioxide, 10 wt% pulp consistency, at a pH of 2 to 3 and a temperature of 75 °C for 120 min.
In one or more examples of the implementation, a more effective process for preparing a paper-based material by ultrasonic-assisted ionic liquid treatment of ECF bleached kraft pulp is 20 provided, including the following steps of:
(1) cooking: placing and cooking eucalyptus chips in a digester, followed by washing completely and screening, to obtain a eucalyptus kraft pulp, where a Kappa number of the pulp ranges from 12 to 16;
(2) ultrasonic-assisted ionic liquid pretreatment, where a dosage of the ionic liquid is 9 wt%, 25 and sonication time is 55 min;
(3) ECF bleaching: conducting the preceding ultrasonic-assisted ionic liquid pretreated pulp on ECF bleaching, where the bleaching sequence is OAD1EOPD2: firstly, conducting the ultrasonic-assisted ionic liquid pretreated pulp onto oxygen delignification (O stage), and
Pl0311.AU Specification 18/02/2020
2020100238 27 Feb 2020 washing the pulp after the O stage; then conducting acid treatment (A stage), and washing the pulp after the A stage; then conducting chlorine dioxide bleaching (DI stage), and washing the pulp after the DI stage; then conducting hydrogen peroxide bleaching (Eop stage), and washing the pulp after the Eop stage; then conducting chlorine dioxide bleaching (D2 stage), and washing the pulp after the D2 bleaching stage, to obtained a bleached pulp; and (4) preparing handsheet with the OAD1EopD2 bleached pulp.
In the series of embodiments, detailed procedures of the cooking in step (1) include steps of: selecting 15 to 25 mm long, 10 to 20 mm wide, 3 to 5 mm thick, relatively uniform Australia eucalyptus chips to air-dry naturally, and then cooking to obtain a hardwood eucalyptus kraft pulp, under the following cooking process conditions: 21 wt% alkali (on a Na2O basis, relative to over dried raw material), at 25% sulfidity, a 1:5 liquid ratio, and a maximum cooking temperature of 170 °C; gassing off at 105 °C for 15 min, heating up for 90 min, and holding the temperature for 90 min; after cooking, fully washing and screening the pulp to obtain an unbleached eucalyptus kraft pulp.
Another embodiment of the present disclosure provides a paper-based material prepared by the preceding process. The paper-based material possesses not only presents better physical strength properties, but also higher brightness.
To enable those skilled in the art to understand the technical solutions of the present disclosure more clearly, the technical solutions of the present disclosure will be further described in detail in combination with specific embodiments.
Analytical methods used in embodiments are as follows:
Determination of brightness: After a pulp is dispersed in a defibrator, paper is formed and pressed into a handsheet on a handsheet former (Austria) and determined by YQ-Z-48B brightness meter.
Folding number is determined by an MIT folding tester (MIT, China).
Burst index is determined by a burst tester (L&W, Sweden).
Tensile strength is determined by an XLWA(B) Intelligent Electronic Tensile Testing Machine (Labthink, China).
Tear index is determined by an MIT tear tester (MIT, China).
The remaining experimental methods unspecified are all conventional in the art.
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The principles of the present disclosure are as follows: The ionic liquid is used to destroy a hydrogen-bonded network of fiber to dissolve out lignin, loosening the fiber structure, increasing the degree of fiber swelling, improving morphology of fines components, and enhancing the interaction between fibers. Ultrasonic cavitation is used to improve accessibility of pulp fiber. Meanwhile, ultrasonic-assisted ionic liquid pretreatment is less destructive for the hydrocarbon framework, promotes the permeation of subsequent bleaching agents, the destruction of chromophoric groups in the pulp, and the diffusion and dissolution of bleaching reaction products, and further improves properties of bleached pulp paper materials.
Embodiment 1.
Steps are as follows:
(1) Cooking conditions were: 21 wt% alkali (on aNa2O basis), at 25% sulfidity, a 1:5 liquid ratio, and a maximum cooking temperature of 170 °C; gassing off at 105 °C, heating up for 90 min, and holding the temperature for 90 min. After cooking, a pulp was fully washed and screened to obtain an unbleached pulp.
(2) Ultrasonic-assisted ionic liquid pretreatment: One bag (25 g) of pulp (on an over dry stock basis) was accurately weighed, and 9 wt% triethylammonium hydrogen sulfate (TEA-HSO4) ionic liquid was charged into the pulp in a polyethylene (PE) bag, where pulp consistency was adjusted to 10%. After curlating until well mixed, the pulp was treated in ultrasonic equipment for 55 min at an ultrasonic power of 250 W.
(3) ECF bleaching: The preceding ultrasonic-assisted ionic liquid pretreated pulp was bleached according to an OADiEopD2 bleaching sequence. Firstly, oxygen delignification (O stage) was conducted on a eucalyptus kraft pulp under the following process conditions: 10% pulp consistency, 3 wt% NaOH, 0.6 wt% MgSCM, at a temperature of 100°C for 60 min under oxygen pressure of 0.5 MPa; the pulp was washed after that. Then acid treatment (A stage) was conducted under the following process conditions: at a pH of 3.5 to 4.5 for 120 min; the pulp was washed after treatment. Chlorine dioxide bleaching (Di stage) was conducted under the following process conditions: 0.7 wt% chlorine dioxide, 10 wt% pulp consistency, at a pH of 2 to 3 and a temperature of 70 °C for 30 min; the pulp was washed after bleaching. Subsequently, hydrogen peroxide bleaching (Eop stage) was conducted under the following process conditions: 1 wt% 30 hydrogen peroxide, 10 wt% pulp consistency, at a pH of 11 to 12 and a temperature of 90 °C for 60 min under oxygen pressure of 0.4 MPa; the pulp was washed after treatment. Subsequently, chlorine dioxide bleaching (D2 stage) was conducted under the following process conditions: 0.8
P10311.AU Specification 18/02/2020
2020100238 27 Feb 2020 wt% chlorine dioxide, 10 wt% pulp consistency, at a pH of 2 to 3 and a temperature of 75 °C for 120 min, the pulp was washed after bleaching.
(4) Handsheet: The OADiEopD2 bleached pulp was beaten to 60 °SR; the pulp was then dispersed with water and formed 80 g/m2 paper-based material on a handsheet former.
(5) Meanwhile, OADiEopD2 bleached pulp without ultrasonic-assisted ionic liquid pretreatment was selected to beat to 60 °SR; the pulp was then dispersed with water and formed 80 g/m2 paper-based material on a handsheet former.
(6) Performance of the paper-based materials obtained is shown in Table 1. With the same pulp fiber raw material, all performance indexes of the ultrasonic-assisted ionic liquid pretreated paper-based material were superior to those of the untreated paper-based material bleached under conventional conditions.
Table 1 Performance indexes of paper-based materials manufactured by OADiEopD2 bleached eucalyptus pulp with ultrasonic-assisted TEA-HSO4 treatment and that without ultrasonic-assisted ionic liquid treatment.
| Example | Type of ionic liquid | Folding endurance /Time | Tensile strength /kN -m | Tear index /mN Tru-g’1 | Burst index / kPa»m2»g'1 | Brightness / %ISO |
| Embodiment 1 | TEA-HSO4 | 349 | 5.01 | 7.99 | 4.31 | 75.9 |
| Conventional | - | 115 | 4.35 | 6.75 | 4.06 | 75.2 |
j Results: After determination, performance indexes of the bleached eucalyptus pulp without pretreatment are as follows: brightness 75.2%ISO, tensile strength 4.35 N-nrg’1, tear index 6.75 mN-m2-g·', burst index 4.06 kPa-m2-g_|, and folding endurance 115 times. Compared with the bleached pulp pretreated with ultrasonic-assisted ionic liquid treatment under the same bleaching process conditions, performance indexes of the pulp pretreated in 9 wt% (on an over dry pulp 20 basis) triethylammonium hydrogen sulfate (TEA-HSO4) ionic liquid with ultrasonication for 55 min increase: folding endurance increases by 203.5%, tensile strength by 15.2%, tear index by 18.4%, burst index by 6.2%, and brightness by 0.9%. Evidently, both bleachability and physical strength properties of the ultrasonic-assisted ionic liquid pretreated pulp are improved.
Embodiment 2:
Steps are as follows:
P10311.AU Specification 18/02/2020
2020100238 27 Feb 2020 (1) Cooking conditions were: 21 wt% alkali (on aNa2O basis), at 25% sulfidity, a 1:5 liquid ratio, and a maximum cooking temperature of 170 °C; gassing off at 105 °C, heating up for 90 min, and holding the temperature for 90 min. After cooking, a pulp was fully washed and screened to obtain an unbleached pulp.
(2) Ultrasonic-assisted ionic liquid pretreatment: One bag (25 g) of pulp (on an over dry stock basis) was accurately weighed, and 9 wt% l-butyl-3-methylimidazolium hydrogen sulfate (BMIM-HSO4) ionic liquid was charged into the pulp in a polyethylene (PE) bag, where pulp consistency was adjusted to 10%. After curlating until well mixed, the pulp was treated in ultrasonic equipment for 55 min at an ultrasonic power of 250 W.
(3) ECF bleaching: The preceding ultrasonic-assisted ionic liquid pretreated pulp was bleached according to an OADiEopD2 bleaching sequence. Firstly, oxygen delignification (O stage) was conducted on a eucalyptus kraft pulp under the following process conditions: 10% pulp consistency, 3 wt% NaOH, 0.6 wt% MgSCM, at a temperature of 100 °C for 60 min under oxygen pressure of 0.5 MPa; the pulp was washed after that. Then acid treatment (A stage) was conducted under the following process conditions: at a pH of 3.5 to 4.5 for 120 min; the pulp was washed after treatment. Chlorine dioxide bleaching (Di stage) was conducted under the following process conditions: 0.7 wt% chlorine dioxide, 10 wt% pulp consistency, at a pH of 2 to 3 and a temperature of 70 °C for 30 min; the pulp was washed after bleaching. Subsequently, hydrogen peroxide bleaching (Eop stage) was conducted under the following process conditions: 1 wt% hydrogen peroxide, 10 wt% pulp consistency, at a pH of 11 to 12 and a temperature of 90 °C for 60 min under oxygen pressure of 0.4 MPa; the pulp was washed after treatment. Subsequently, chlorine dioxide bleaching (D2 stage) was conducted under the following process conditions: 0.8 wt% chlorine dioxide, 10 wt% pulp consistency, at a pH of 2 to 3 and a temperature of 75 °C for 120 min, the pulp was washed after bleaching.
(4) Handsheet: The OADiEopD2 bleached pulp was beaten to 60 °SR; the pulp was then dispersed with water and formed 80 g/m2 paper-based material on a handsheet former.
(5) Meanwhile, OADiEopD2 bleached pulp without ultrasonic-assisted ionic liquid pretreatment was selected to beat to 60 °SR; the pulp was then dispersed with water and formed 80 g/m2 paper-based material on a handsheet former.
(6) Performance indexes of the paper-based material obtained are shown in Table 2. With the same pulp fiber raw material, all performance indexes of the ultrasonic-assisted ionic liquid
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2020100238 27 Feb 2020 pretreated paper-based material were superior to those of the untreated paper-based material bleached under conventional conditions.
Table 2 Performance indexes of paper-based materials manufactured by OADiEopD2 bleached eucalyptus pulp with ultrasonic-assisted BMIM-HSO4 treatment and that without ultrasonic-assisted ionic liquid treatment
| Example | Type of ionic liquid | Folding endurance /Time | Tensile strength /kN -m | Tear index /mN Tru-g’1 | Burst index / kPa»m2,g·1 | Brightness / %ISO |
| Embodiment 2 | BMIM-HSO4 | 281 | 4.55 | 7.92 | 4.24 | 75.7 |
| Conventional | - | 115 | 4.35 | 6.75 | 4.06 | 75.2 |
Results: After determination, performance indexes of the bleached eucalyptus pulp without pretreatment are as follows: brightness 75.2%ISO, tensile strength 4.35 N-nrg’1, tear index 6.75 mN-m2-g·*, burst index 4.06 kPa-m2-g_|, and folding endurance 115 times. Compared with the bleached pulp pretreated with ultrasonic-assisted ionic liquid under the same bleaching process conditions, performance indexes of the pulp pretreated in 9 wt% (on an over dry stock basis) 1butyl-3-methylimidazolium hydrogen sulfate (BMIM-HSO4) ionic liquid with ultrasonication for 55 min increase: folding endurance increases by 144.3%, tensile strength by 4.6%, tear index by 17.3%, burst index by 4.4%, and brightness by 0.6%. Evidently, both bleachability and physical strength properties of the ultrasonic-assisted ionic liquid pretreated pulp are improved.
The foregoing is merely illustrative of the preferred embodiments of the present invention and is not intended to limit the present invention, and various changes and modifications may be made by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention should be included within the protection scope of the present invention.
Claims (5)
- What is claimed is:1. A process for preparing a paper-based material by ultrasonic-assisted ionic liquid treatment of ECF bleached kraft pulp, wherein ultrasonic-assisted ionic liquid pretreatment is performed on an unbleached kraft pulp, then the obtained kraft pulp is subjected to ECF bleaching, and in the pretreatment process, a dosage of the ionic liquid is 9 wt%, and sonication time is 55 min.
- 2. The process according to claim 1, wherein the unbleached kraft pulp is a pulp obtained by kraft cooking of eucalyptus; wherein anions in the ionic liquid comprise any one of HSOC or CT ion, or a mixture thereof, and cations comprise any one of l-butyl-3-methylimidazolium or triethylammonium ion, or a mixture thereof; wherein a sequence of the ECF bleaching is OADiEopD2, comprising steps of: firstly, conducting a pretreated pulp on oxygen delignification (O stage), and washing the pulp after the O stage; then conducting acid treatment (A stage), and washing the pulp after the A stage; then conducting chlorine dioxide bleaching (Di stage), and washing the pulp after the DI stage; then conducting hydrogen peroxide bleaching (Eop stage), and washing the pulp after the Eop stage; then conducting chlorine dioxide bleaching (D2 stage), and washing the pulp after the D2 bleaching stage, to obtain a bleached pulp, preferably, wherein detailed process conditions of the OADiEopD2 bleaching sequence comprise: oxygen delignification (O stage): 10% pulp consistency, 3 wt% NaOH, 0.6% MgSCf, at a temperature of 100 °C for 60 min under oxygen pressure of 0.5 MPa; acid treatment (A stage): at a pH of 3.5 to4.5 for 120 min; chlorine dioxide bleaching (Di stage): 0.7 wt% chlorine dioxide, 10 wt% pulp consistency, at a pH of 2 to 3 and a temperature of 70 °C for 30 min; hydrogen peroxide bleaching (Eop stage): 1 wt% hydrogen peroxide, 10 wt% pulp consistency, at a pH of 11 to 12 and a temperature of 90 °C for 60 min under oxygen pressure of 0.4 MPa; chlorine dioxide bleaching (D2 stage): 0.8 wt% chlorine dioxide, 10 wt% pulp consistency, at a pH of 2 to 3 and a25 temperature of 75 °C for 120 min.
- 3. The process according to claim 1, comprising the following steps of: (1) cooking: placing and cooking eucalyptus chips in a digester, washing completely and screening after cooking, to obtain a eucalyptus kraft pulp, wherein a Kappa number of the pulp ranges from 12 to 16; (2) ultrasonic-assisted ionic liquid pretreatment; (3) ECF bleaching: conducting the ultrasonic-30 assisted ionic liquid pre treated pulp onto ECF bleaching, wherein the bleaching sequence is OAD1EOPD2: firstly, conducting the ultrasonic-assisted ionic liquid pretreated pulp onto oxygen delignification (O stage), and washing the pulp after the O stage; then conducting acid treatment (A stage), and washing the pulp after the A stage; then conducting chlorine dioxide bleaching (DiP10311.AU Specification 18/02/20202020100238 19 Feb 2020 stage), and washing the pulp after the Di stage; then conducting hydrogen peroxide bleaching (Eop stage), and washing the pulp after the Eop stage; then conducting chlorine dioxide bleaching (D2 stage), and washing the pulp after the D2 bleaching stage, to obtained a bleached pulp; and (4) preparing handsheet with the OADiEopD2 bleached pulp.
- 4. The process according to claim 1, wherein detailed procedures of the cooking in step (1) comprise steps of: selecting 15 to 25 mm long, 10 to 20 mm wide, 3 to 5 mm thick, relatively uniform Australia eucalyptus chips to air-dry naturally, and then cooking to obtain a hardwood eucalyptus kraft pulp, under the following cooking process conditions: 21 wt% alkali, at 25% sulfidity, a 1:5 liquid ratio, and a maximum cooking temperature of 170 °C; gassing off at 105 °C for 15 min, heating up for 90 min, and holding the temperature for 90 min; after cooking, fully washing and screening the pulp to obtain an unbleached eucalyptus kraft pulp.
- 5. A paper-based material prepared by the process according to any one of claims 1 to 4.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111826984A (en) * | 2020-07-09 | 2020-10-27 | 天津科技大学 | Method for improving softness of high-yield bamboo pulp fibers through ultrasonic-assisted ozone treatment |
| CN113524821A (en) * | 2021-07-13 | 2021-10-22 | 东北林业大学 | Shell-structure-simulated ultrahigh-content cellulose-reinforced polymer composite material and preparation method thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111826984A (en) * | 2020-07-09 | 2020-10-27 | 天津科技大学 | Method for improving softness of high-yield bamboo pulp fibers through ultrasonic-assisted ozone treatment |
| CN113524821A (en) * | 2021-07-13 | 2021-10-22 | 东北林业大学 | Shell-structure-simulated ultrahigh-content cellulose-reinforced polymer composite material and preparation method thereof |
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