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    Surface Modification of Nano Calcium Carbonate and Its Application in Papermaking
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                Abstract: The nano calcium carbonate as a functional material with excellent physical and chemical properties, has been widely used in the paper industry. In this paper, nano-calcium carbonate surface modification methods, and applications of nano calcium carbonate in the paper industry were reviewed in order to provide a reference for related research.
    Keywords: Nano Calcium Carbonate Surface Modification modifier Paper
    Nanomaterials since the advent of the 1980s, in the chemical, electronics, defense, ceramics and other industrial areas has been amply demonstrated that it is in the field of pillar industries and high-tech application of enormous potential, causing the world's polar scientists Great attention. Nanotechnology is the study of the 10 ~ 100nm scale space electrons, atoms, molecules, and movement of high-tech nature, have been countries in the world, especially in Western countries as the focus of basic and applied research in the 21st century. Rohrer Nobel laureate once said: 70s (last century) emphasis micron countries now have become a developed country, now pay attention to nanotechnology countries are likely to become an advanced country in the 21st century [1]. Nanotechnology is the world's research and development focus in China is still in its infancy, most of the achievements still remain in the laboratory, but nanometer superfine calcium carbonate can be one of the industrialization of the few species. Nano calcium carbonate because of its source material readily available, low cost, low toxicity, low pollution, high whiteness, good filling and mixing process large performance characteristics such as rubber, plastic, paper and the largest amount of light One of filler.
    Nano calcium carbonate having a small particle size high surface energy, easily reunion, oleophobic and hydrophilic surface characteristics strongly polar, non-uniform dispersion in an organic medium. Nano calcium carbonate used directly in organic medium has two drawbacks: First, the intermolecular forces reunion, electrostatic, hydrogen bonding caused by calcium carbonate powder. The large surface area of ??nano calcium carbonate, easily adsorbed gas, media, or its role, which lost its original surface properties, resulting in adhesion and agglomeration, or because of a high surface energy and a larger contact surface, the grain growth accelerated; Also the nano mutually coupled quantum tunneling effect, charge transfer and interfacial atoms of calcium carbonate to interact and because of the solid phase reaction reunion. The second is a hydrophilic inorganic nano-calcium carbonate compound, its surface more hydrophilic hydroxyl, was strongly alkaline, it deteriorates the affinity with the organic polymer, easy to form aggregates, resulting in high copolymer dispersed unevenly, causing defects in the interface between the two materials, direct application ineffective. With the increasing amount of nano calcium carbonate, these shortcomings more obvious, overfilling even make products not use [2-4]. Therefore, the need for surface modification of nano calcium carbonate to the surface can be reduced, the dispersion is improved, the surface was lipophilic, thereby increasing the affinity of nano calcium carbonate and polymers. In this paper, nano-calcium carbonate surface modification methods, and applications of nano calcium carbonate in the paper industry were reviewed in order to provide a reference for related research.
    Surface Modification 1 nanometer calcium carbonate
    Surface modification of nano calcium carbonate is by physical or chemical adsorption method of surface treatment agent (or reaction) in the nano calcium carbonate surface, forming an envelope, to activate the surface, thereby improving the surface properties of nanometer calcium carbonate. By modifying the surface of the nano calcium carbonate, can achieve the purpose of the following aspects of the [5-8] :( 1) reduce the cohesion between particles, improve and enhance the dispersion of nano calcium carbonate; (2) increasing Nano carbonate Surfactants of calcium; (3) to improve the nano calcium carbonate and other substances compatibility; (4) increasing the acid resistance of nano calcium carbonate; (5) Preparation of specific crystalline calcium carbonate, used in different industries. Surface treatment agent according to the present structure and properties can be divided into a surfactant, a coupling agent, and inorganic polymers.
    1.1 Surfactant
    Chang-Jian et al [9] studied the effect of various types of anti-surfactant aggregates of nano calcium carbonate, and the results show that the surface-active agent to improve the dispersion effect of the merits of the order of anionic, nonionic, cationic, polymer, surfactant compound improving effect with a single type of material is superior to surfactant. Currently the application of more surfactants are fatty acid (salt), a polymer compound and phosphate (salt).
    1.1.1 fatty acid (salt)
    Fatty acid for surface treatment of nano calcium carbonate mainly containing hydroxyl, amino fatty acid salts of fatty acids, or aryl group [10]. About fatty acid (salt) on the mechanism of nano calcium carbonate, model Vold, argues that the fatty acid (salt) in the periphery of the particles form a shell, increases the nearest distance between two particles, reducing the van der Waals attraction to each other the role of the dispersion is stabilized [11]. Currently the most used, the best fatty acid (salt) is stearic acid (salt). Duzhen Xia et al [12] with stearic acid modified nano calcium carbonate were studied and found that the modifier adsorbed on the surface of nano calcium carbonate, and incorporated ionic bond. Transmission electron microscopy analysis showed that modified nano calcium carbonate in cyclohexane dispersion significantly improved particles are monodisperse state, the lipophilic property, in a non-polar dispersion medium is improved. Han Yuexin et al. [13] The use of nano calcium stearate Surface Modification by IR analysis indicates the formation of a strong bond between stearic acid and calcium carbonate. Zhubu Yao Gu Ti al. [14] The two-stage model of the modified activity of calcium carbonate content and the amount of S-curve modifiers explained more successful. The first stage is an individual modifier molecules or ions with a solid surface by van der Waals attraction interact directly be adsorbed. The second stage, modifier molecules or ions through hydrophobic interactions between the hydrocarbon chains micelle-forming surface adsorption sharp rise, then the first phase adsorption monomer to form a center of the surface of the micelles. According to the model theory, one of the fundamental physical and chemical characteristics of the surfactant micelles in aqueous solution generated above a certain concentration in. Modifier molecules adsorbed on the surface of calcium carbonate does not change its amphiphilic, still exhibits hydrophobic hydrocarbon chain effect. Above certain concentrations, these amphiphilic molecule adsorbed on the surface of calcium carbonate compounds involved in the formation of hydrophobic association, and more modifiers fixed at the interface, resulting in increased adsorption capacity [11]. Chapter Masahiro and other tests were performed [15] human presence adsorption isotherm rapidly rising phase, further validates the two-stage model.
    1.1.2 polymer compound
    In general, the available multi-polymer compound containing a sulfonic acid group or a carboxylic acid group and the like, basically a number of ionizable groups. These groups and nanoparticles of a particular element to form a strong ionic bonds, thus stabilizing the particles plays a vital role. In addition, most polar molecules may also play a similar protective effect [16]. Liu cited Feng et al. [17-19] The polymer compound having a hydroxyl group, an amine, carbonyl and carboxyl groups as polar dispersant also received good results. Compared with the band may polymer compound ionizable groups, polar polymer compound also has some unique advantages. [20] Chen Huijuan and other research shows that when the relative molecular mass of 3000 to 4000, sodium polyacrylate dispersion stabilizing effect of nano-calcium carbonate is better. Zhang Na, etc. [21] and Ren Jun [22] self-designed and synthesized respectively and ND426 ND polymer dispersant having a colorless, odorless characteristics of ultra-fine calcium carbonate suspension dispersion and rheology better, and has no effect on the whiteness of the white powder, it helps to improve the quality Superfine calcium carbonate. In addition, the use of a polymer compound as a dispersant not only because of its protective effect, but also want to use a polymer compound itself good optical properties and excellent physical properties make nanomaterials with a polymer compound complex, you can have the new optical characteristics and excellent molding characteristics.
    1.1.3 phosphates (salt)
    With phosphate surface modification of nano calcium carbonate is mainly calcium phosphate nano surface reaction of calcium phosphate is deposited or coated on the surface of nano calcium carbonate particles, so that the surface was hydrophobic nano calcium carbonate [ twenty three]. In phosphate nano calcium carbonate as a surface modifier, not only can make processability and physical properties of the composites is significantly improved, and for acid resistance and flame retardance improving effect is more apparent.陳小萍 et al [24] studied the series of phosphate ester surfactant modification effect of nano calcium carbonate, and the results showed that modified nano calcium carbonate surface by the hydrophilic to lipophilic, thereby significantly reducing the nanometer calcium carbonate with neighbors The viscosity of the paste dioctylphthalate (DOP), reduced oil absorption of nano calcium carbonate; modifying effect monoester than double ester. Yanhai Biao et al [25] studied the PVC / new phosphate-modified nano calcium carbonate composite microstructure and physical properties of PVC found Modified Nano composites have significant toughening effect, can improve the physical properties. Zhang et al [26] studies have indicated that in the selection of modifiers should be selected with a similar modifier to be filled according to the characteristics of the molecular structure of polymer systems.
    1.2 coupling
    Coupling portion of the molecule groups can be various functional groups reactive mineral surfaces and form a strong chemical bond; another part groups can chemical reactions or physical wound with an organic polymer material occurs, thereby Two Different minerals and organisms great material firmly joined, namely nano calcium carbonate surface molecules by means of coupling the bridge, so that the nano calcium carbonate and organic polymer material compatibility is improved [3]. Money Zhimian et al [27] that the coupling occurs at the surface of inorganic adsorption, or play a role in the role of some of the function keys, so that the coupling agent capable of forming a surface covering inorganic filler. Cheng Shui-lin [28] that the modifier and inorganic filler surface is mainly Ca2 +, hydroxyl and other active groups chemical adsorption or physical adsorption, coated on the surface of the filler. Increasing the amount of filler coupling can also improve the rheological properties of the system.湯志松 et al. [29] By examining the process of modification of the specific route proposed activation - Orientation - equilibrium adsorption assumption that the coupling agent dispersed nano-calcium carbonate suspension after adsorption occurs with the free OH- and in a specific direction in nano-calcium carbonate surface adsorption, and finally to two adsorption equilibrium. Since surface adsorption of nano-calcium carbonate is formed micelles, adsorption greater resistance, so the absorption of nano calcium carbonate surface have a comparative advantage. Currently coupling agents for nano calcium carbonate are mainly titanate coupling agent, aluminum coupling agent and a composite coupling agent.
    1.2.1 titanate coupling agent
    Titanate coupling agent 1974 US Kenrich company first invention is an inorganic filler such as calcium carbonate widely used surface modifiers, rubber and thermoplastics modified better. 1977 MonteSJ et al [31 to 33] proposed a titanate coupling agent to form a single molecular layer are arranged in the filler surface. HanCD et al. [33, 34] proposed a titanate coupling agent having a plasticizing effect and interfacial bonding role in filling the system, after titanate coupling agent modified nano calcium carbonate surface covered with a monomolecular film, thereby nano calcium carbonate radically alter the surface properties [35]. According to the mechanism of molecule and coupling agent, it has the practical application of titanate coupling main monoalkoxy type, monoalkoxy pyrophosphate type, chelating ligand type and size. Titanate coupling agent modification is better, has been widely used, but its impact on the environment and human health have been more and more attention in developed countries, the United States has for the titanate coupling agent in rubber nipples and products in the content and toys made strict rules. China also titanate coupling a lot of research, Zhaixiong Wei et al. [36] The titanate coupling NDZ2101, NDZ2201 and NDZ2311 modified nano calcium carbonate-filled rigid PVC, when the mass fraction of nano calcium carbonate sample 0.3, the notched impact strength than the coupling agent is not added, respectively, by 56%, 36% and 46%. Rossby equality [37] The titanate coupling TSC modified PCC filled NR, when calcium carbonate mass fraction of 15%, the tensile strength of rubber increased from unmodified when 17.4MPa to 19.4MPa, filled with silica gel (19.9MPa) close. Wang Xun Qiu et al [38] who make the complex coupling agents, titanium esters and stearic acid compound modification, calcium carbonate can be stably dispersed in xylene after modification, for use in coating the foundation, which can greatly broaden the applications of Nano CaCO3.
    1.2.2 aluminum coupling agent
    1986 Zhang Wen Gong et al. [39] invented the aluminum coupling agent. Free proton alkoxy aluminum nano calcium carbonate surface easily hydrolyzed ester molecule chemical reaction, and the other end group and polymer molecular chain molecules occurs wound or cross-linking. Domestic production of primary aluminum coupling agent has DL2411 and DL2451 series. Far Ren et al. [40] The aluminum coupling agent modified nano calcium carbonate filled PVC DL24112A found elongation at break and impact strength of the composites compared with unmodified nano calcium carbonate has improved significantly. Lin Meijuan et al. [41] The aluminum coupling agent DL24112D modified nano calcium carbonate having an oil absorption value and water absorption decreases, in an organic medium with good distribution. In addition, 徐偉平 et al [42] studied the molecular coupling of surface modified nano calcium carbonate, the results showed the macromolecular coupling can significantly improve the processing performance filling system.
    1.3 Polymer
    Orientable polymer adsorbed on the surface of calcium carbonate, calcium carbonate having a charge characteristics, and physical and chemical adsorption layer formed on the surface thereof, agglomerated calcium carbonate particles to prevent caking and improve the dispersibility. Generally it believed that polymer-coated calcium carbonate can be divided into two categories: one is the first polymerization monomers adsorbed on the surface of calcium carbonate, then initiated polymerization to form a thin polymer layer on its surface; the other The polymer is dissolved in a suitable solvent and adding calcium carbonate to exclude when the polymer is gradually absorbed on the surface of calcium carbonate solvent to form a capsule. Now the use of this polymer dispersion have synthesized a number of uniform size, good dispersion of nanoparticles [43]. PMMA polymer wrapped treated nano calcium carbonate can reach nano-dispersion level, to play a toughening PP enhance the role [44].何濤波 et al. [45] people covered with polymethyl methacrylate calcium carbonate, after tests showed that, PMMA is grafted on the surface by the action of CaCO3 C atoms occur. In addition, with an alkyl group, styrene - styrene sulfonic acid copolymers of nano calcium carbonate surface treatment can also improve the dispersion of nano calcium carbonate. The polyolefin oligomer nano inorganic fillers such as calcium carbonate have better infiltration, adhesive effect. Maleic anhydride-grafted modified polypropylene, polyacrylic acid (salt), alkoxy styrene, polyethylene glycol and a reactive cellulose can better improve the wetting properties of nano calcium carbonate. Such polar oligomers can be directionally adsorbed on the surface of the nano calcium carbonate to have charge characteristics and the formation of the adsorbed layer to prevent agglomeration, thus increasing its dispersion.
    1.4 inorganics
    Inorganic electrolyte dispersant nano calcium carbonate surface adsorption, one can significantly increase the absolute value of the surface potential of nano calcium carbonate, resulting in a strong electric double layer electrostatic repulsion; on the other hand, the adsorption layer can induce a strong steric repulsion effect. Meanwhile inorganic electrolytes may also enhance the degree of surface wetting of nano calcium carbonate for water, thus effectively preventing agglomeration of nano calcium carbonate in the water has condensed such inorganic phosphate, sodium aluminate, sodium silicate, alum, etc. [3]. Due to the presence of nano calcium carbonate acid poor surface pH value and other shortcomings, limiting the expansion of its range of use. Using condensed phosphoric acid for surface treatment of nano calcium carbonate to form a condensed phosphoric parcel layer on its surface, thereby improving the acid resistance [46].李凱奇 et al [47] studied a new type dispersing agent A-type zeolite, sodium tripolyphosphate when it is used in conjunction with the nano calcium carbonate has a good dispersion. The dispersant is insoluble in water, there is no bonding properties when dry, to solve the problem of nano calcium carbonate dry good help.
    2 Nanometer Calcium Carbonate in Papermaking
    2.1 calcium carbonate as a filler paper
    As the papermaking process shift from acidic to alkaline sizing sizing, application of nano calcium carbonate provides a huge potential market. Plus use of nano calcium carbonate filler has many advantages [50]: ① has a high opacity, high brightness, paper products can improve the whiteness and opacity. ② enable paper mills to use more filler and less pulp, can greatly reduce the production cost. ③ Nano Calcium carbonate fine and even a small paper machine wear, and enable the production of paper products more uniform and smooth. ④ oil absorption of nano calcium carbonate is high, can improve color fastness of pigment paper. ⑤ when using nano calcium carbonate filled neutral paper or cardboard, paper or cardboard can be improved tightness. Thus, nano calcium carbonate as filler paper has a high bulk density, good plasticity and softness, delicate surface of the paper, can greatly improve the performance of paper. You can reach to a higher level of fill rate coefficient. The amount can be as high as nearly 30 percent. Opaque paper is mainly used for the production of higher grades to reduce production costs, so paper-making enterprises to achieve significant economic benefits.
    2.2 calcium carbonate in Surface Sizing
    Nano calcium carbonate with high brightness, large surface area, high surface activity, excellent strength and high hardness properties. Addition of nano calcium carbonate in surface sizing, you can get a high gloss and high ink absorption of paper, and improve the smoothness of the paper [52]. As the advantages of nano calcium carbonate pigment surface sizing paper mainly in the following several important physical and chemical indicators: (1) improve the IGT nap strength; (2) to improve the whiteness; (3) improve the K & N ink absorption; (4 ) improve the smoothness of the paper. Chuan Shan et al. [53] who use ultra-fine calcium carbonate pigment surface sizing, improved paper quality. Zhang Heng TRANSACTIONS et al [54, 55] studied the nano CaCO3 coatings and coated paper Properties of the appropriate amount of nano-CaCO3 can improve the performance of the coated paper surface strength and ink absorption, but with excessive, if dispersed poor agglomeration of particles coated paper will result in performance degradation.肖仙英 et al. [56] The nano calcium carbonate for paper coating experiment conclude that in the case of the same adhesive, dispersant amount, to the general coating formulations incorporating small amounts of calcium carbonate, can improve strength of the coating, smoothness, while absorbing properties of the ink also has some improvement.
    3 Conclusion
    Nano calcium carbonate is one of the largest cases of nanomaterials and nano calcium carbonate of relatively simple products, product quality is relatively low. Therefore, strengthening the research and development of high-grade calcium carbonate, increase the development of ultra-fine, ultra-pure nano-calcium carbonate is of great significance, the use of the rich resources of the favorable conditions, the original manufacturers for the production of precipitated calcium carbonate production technology and techniques transformation, and further improve the quality of the calcium carbonate product. It is foreseeable that gravity technology nano calcium carbonate product quality improvement, and greatly reduce the cost of production, further development and modification of nano calcium carbonate, more excellent properties of nano calcium carbonate will be found and applied, so that nano calcium carbonate having a broader market prospects. Disclaimer:
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    Currently rotary machine utilizing waste paper as raw material to produce toilet paper and cardboard factories, high consumption of whole fiber acupuncture blanket, blankets are not due to wear, but because of pollutants deposited on the blanket, resulting in poor dehydration, causing crush and embossing paper sick, we can not continue to use the felt as early as the next machine. A good wash blanket measures that can be done to minimize the occurrence of the above question.
    To solve a single problem between blocking blanket is not enough to rely on mechanical methods, it must be mechanical and chemical treatment and use.
    In the papermaking process the paper and cardboard, waste paper stickies contamination is the main reason for a blanket, so the use of chemicals must have a strong degumming to weaken the adhesive and wool fiber, the blockage of pores stick together force, and then dissolve the glue emulsion, to create conditions for flushing the pores of the blockage.
    Alkali can play with grease, ink, gum rosin and a variety of additives saponification, removing strong, with good results when used in the early days. But there are a lot of insoluble adhesive still remaining in the blanket, with the gradual accumulation of blankets under pressure compaction, clogged pores, single use of the base is not enough, we must join with a penetration, wetting, solubilization, emulsification and dispersion comparison Strong surfactants how to measure the pros and cons of the surfactant, except for comparison in practical applications, it can be judged from the performance characteristics of the surfactant: ① Surface tension: lower surface tension has good wetting performance, the solution quickly penetrate into the adhesive inside .② solubilization: surfactants must have stickies have wetting, penetration, emulsification, dispersion and other effects, its monks aqueous surfactant micelle particles are being solubilized to form a transparent stable solution .③ charge repellence: fibers in an aqueous solution of negatively charged, stickies mostly negatively charged anionic surfactant to increase the density of the negative charge repulsion between the wool fibers and the adhesive is increased, thus speeding wash out from a blanket, so the use of an anionic surfactant. Anionic surfactants hydrocarbon chain length of decontamination influential, strong chain length decontamination ability, but relatively speaking chain elderly wetting, penetration ability poor, which is less than the anionic surfactant place. Can both take into account the non-ionic surfactant, superior performance than the anionic surfactant by reference to the following formula: non-ionic surfactant, such as sulfonated poly (ethylene oxide) ether, or TX-10 (octyl phenol ethoxylates a 10) .3500. 500 NaOH, water 94. "% aqueous dubbed, the temperature is not lower than 500C. by glue at higher temperatures are more soluble in water and easy to emulsify, lower the viscosity of water, In the vacuum dewatering box more in use especially stressed that the cleaning solution to penetrate into the felt, typically 20 minutes and then rinse. for extremely dirty and the plane of the acoustic blanket, use detergent soak 2 hours on again machine.
    Vary due to raw material and machine, in the formulation of cleaning solution, we must first identify the type of sediment clogging the perforations blanket. Then by testing the best mechanical and chemical treatment, to determine the best solution to determine the amount and timing of chemicals. Practice shows that dirty blanket after cleaning, machine speed can be increased by 5 wai, reduce steam consumption by 500, the yield genuine rise, reducing downtime for mill brings profit. Disclaimer:
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    Abstract: The Kappa number of 17.1 fast-growing eucalyptus kraft wood pulp was DQP and (DQ) P bleaching. The results showed that the amount of active chlorine 4.0%, H2O2 amount of 2.5% when, DQP bleached pulp brightness reached 85.4%, (DQ) P bleached whiteness 85.3%; and the pH value (DQ) paragraph 2 ~ Whiteness between 4 little change on the pulp. Both bleached pulp strength are good, at the same freeness DQP bleached pulp has a higher breaking length and burst index; and (DQ) P bleached pulp is higher tear index, and the required beating less energy consumption.
    Keywords: eucalyptus kraft pulp; DQP bleaching; (DQ) P bleaching
    CLC: TS74 Document code: A Article ID: 0254-508X (2007) 06-0065-02
    Multi-stage bleaching equipment of high investment, water and more energy to make bleached pulp costs high. In this study, conventional eucalyptus kraft pulp were (DQ) P two bleach (ie added DTPA bleaching in the D segment, the D, Q have been merged), explores the (DQ) segment available chlorine dosage and the final pH Effect of bleached pulp whiteness; and the effects of drift in the D segment segment DQP3 amount of active chlorine bleach final whiteness.
    1.1 Materials
    Eucalyptus is provided by Guangdong Leizhou Forestry Bureau, the Eucalyptus grandis (EucalyptusGrandis) and jarrah (EucalyptusCamaldulensis) crossbreeding, age of 6 years. Raw materials cut into 30mm × 20mm × 5mm of wood, air-dried after screening store spare.
    1.2 Cooking
    The improved US M / K609-2-10 computer control digester. Conventional kraft cooking conditions: pot installed capacity 1000g (absolutely dry), 23% of the amount of active alkali (as NaOH dollars), a 25% degree of vulcanization, liquid ratio of 1: 4, the maximum temperature of 165 ℃, heating time 125min, holding time 120min. The resulting slurry of 17.1 kappa number, brightness 33.1%, viscosity 909mL / g, fine pulp yield 50.4%.
    1.3 Bleaching
    Polyethylene plastic bag bleached pulp consistency of 10%. Drugs added to the slurry and rub evenly after the bag sealed in a water bath reaction, bleached pulp was washed with deionized water.
    D segment: active chlorine dosage 2.5% ~ 4.0%, 70 ℃, 45min, the final pH of 3.5 to 4.0.
    Q group: There DTPA dosage 0.3%, 70 ℃, 30min, final pH of about 4.
    (DQ) group: active chlorine dosage of 2.5% ~ 4.0%, DTPA amount of 0.3%, 70 ℃, 45min.
    P segment: H2O2 dosage 2.5%, NaOH dosage 1.5%, MgSO4 amount of 0.05%, 90 ℃, 240min
    1.4 refining, paper making and testing
    Bleached pulp mill were carried out on two refiner with PFI, refining concentration of 10%. Paper-making, according to the national standard method for determining the performance of paper on standard paper shaper after refining.
    Results and Discussion
    Optimization 2.1DQP and (DQ) P amount available chlorine bleach
    Previous studies have shown [1], non-wood pulp bleaching sequence using DQP, at a lower dosage of active chlorine and H2O2 can be wheat straw, reed pulp, bagasse and bamboo drift to more than 80% of whiteness. Table 1 shows the same Q, under P condition that affects the amount of available chlorine eucalyptus kraft pulp properties.
    From Table 1, in the same amount of active chlorine, (DQ) P bleached pulp brightness can be at or slightly above the whiteness DQP bleached pulp. Two bleached pulp brightness stability are good, increase the amount of available chlorine to improve the stability of the whiteness of bleached pulp. (DQ) P DQP can be achieved with the same bleaching effect. Two investment bleaching equipment, power consumption and operating costs less than 3 segments drift, therefore, has obvious advantages and potential applications.
    Optimization 2.2 (DQ) segment end pH value
    The pH has a significant effect on the DTPA chelating treatment and ClO2 effect. Active chlorine dosage of 4.0%, the effect (DQ) paragraph final pH of the pulp properties are shown in Table 2.
    Table 2 shows, in an amount of 4.0% available chlorine, it will be the final pH (DQ) segment increased from 2.02 to 3.97, bleached pulp almost unchanged, except for a slight yellowing value increases. Lower pH will DTPA chelating ability of metal ions weakened, but under acidic conditions ClO2 has a strong oxidation resistance, capable of oxidizing metal ions, on the subsequent P-stage bleaching favorable. Therefore, (DQ) final pH value segment bleaching will not have much effect on the bleached pulp from 2 to 4:00; Recommendation (DQ) segment endpoint pH of about 4.
    2.3DQP and (DQ) P refiner bleached pulp papermaking performance comparison
    The amount of active chlorine were 4.0% of refining DQP and (DQ) P bleached pulp, Table 3 shows the number of revolutions pulp properties under different refining.
    From Table 3, after refining the two bleached pulp strength properties were improved, including the breaking length and burst index with the increase of freeness and increased freeness arrive later this trend 48oSR He began to weaken; bleached pulp after beating two tear index also increased significantly, and remained unchanged or slightly lower. At the same freeness, breaking length and burst index DQP bleached pulp than (DQ) P pulp; and when the beating is greater than 30oSR, (DQ) P bleached pulp has a higher tear index. Overall, after beating two bleached pulp strength properties are good. To achieve the same degree of beating, refining revolutions (DQ) P bleached pulp require less than DQP bleached pulp, which requires less refining energy.
    3 Conclusions
    3.1 Kappa number of 17.1 unbleached eucalyptus kraft pulp in active chlorine dosage of 4.0%, H2O2 amount of 2.5% when, DQP and (DQ) P bleached pulp can reach more than 85% of whiteness, and has a relatively Good whiteness stability. Endpoint pH (DQ) stage is about 4 better.
    3.2 At the same freeness, breaking length and burst index DQP bleached pulp than (DQ) P bleached pulp; higher than when beating 30oSR, (DQ) P tear index higher than DQP; to achieve the same pulp freeness, (DQ) P lower bleached pulp refining energy. Disclaimer:
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    2, site reproduced works are indicate the source, such as violations of authorship reproduced works, not because this site deliberately, after receiving notice from the relevant rights will be corrected.
    Some plant-based pulp is processed, it is the basic raw material for papermaking. Commonly used to feed the pulp plant can be divided into four categories: the stem fiber, bast fiber, seed hair fiber and wood fiber. Particularly in the wood fiber is the most important. At present China's timber resources can not meet the growing needs of the pulp and paper industry. To compensate for the lack of raw materials, imported from abroad every year a considerable amount of pulp.
    Pulping process

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