-->制浆造纸工艺技术

Effects of Alkali Dosage on the Mechanical Properties of Sisal Pulp Fibers During NaOH-AQ Cooking Process

LI Jie,LIU Mengru,LI Hailong,LI Yage,QIN Xiao — 2024/10/8 10:57:08

This study systematically evaluated the mechanical properties of sisal pulp fibers under different alkali dosages during the NaOH-AQ cooking process. It also analyzed the fiber morphology， microfibril angle， crystallinity， and lignin content to explore their synergistic effect on the mechanical properties of individual fibers. The results showed that as the alkali dosage increased from 12% to 30%， the elastic modulus of sisal pulp single fibers decreased from 12.60 GPa to 6.99 GPa， the softness index increased from 0.54×10¹⁷/（N·m²）to 3.15×10¹⁷/（N·m²）， the cell wall hardness reached its maximum value of 449.20 MPa at alkali dosage of 18%， and the zero-span tensile index of the fibers reached its maximum value of 177 N·m/g at alkali dosage of 15%.

Research on the Mechanism of Sinocalamus Affinis Kraft Cooking

CHEN Huiqin,LI Bingyun,LI Hailong — 2024/10/8 10:57:09

In this paper， the chemical components of sinocalamus affinis were analyzed. The lignin content， holocellulose content， and pentoan content during kraft cooking were studied， and the cooking process was revealed. The results showed that the content of cellulose， lignin， and hemicellulose were 44.35%， 25.88%， and 28.27%， respectively. Indicating that sinocalamus affinis was an excellent non-wood papermaking fiber raw material. The delignification process of sinolalamus affinis kraft cooking could be divided into three stages including the stage of bulk delignification， the stage of supplementary delignification， the stage of residual delignification. In the stage of bulk delignification， the delignification rate reached to 46.40%， the carbohydrate degradation rate reached to 28.11%， and the pentosan dissolution rate reached to 48.63%. In the stage of supplementary delignification， the delignification rate reached to 89.72%， the carbohydrate degradation rate was 38.71% and the pentosan dissolution rate was 97.93%. In the stage of residual delignification， the delignification rate was 96.14%， the carbohydrate degradation rate was 38.82%， and the pentosan dissolution rate was 94.39%.

Microwave-assisted Choline Chloride/Lactic Acid Deep Eutectic Solvents Pulping to Produce Wood Fibers with High Degree of Polymerization

HUANG Pan,YANG Dongjie,ZHOU Jie,LI Yujie,FANG Zhiqiang — 2024/10/8 10:57:11

Wood fibers with high cellulose polymerization degree （DP） were prepared via microwave-assisted deep eutectic solvents pulping method using spruce wood chips as material and choline chloride/lactic acid as reaction liquid， and the effects of molar ratio of choline chloride to lactic acid， reaction temperature， reaction time， and water content on cellulose DP were investigated. The results showed that microwave heating shortened the time for delignification， which decreased the acid hydrolysis of cellulose in the acidic medium and maintained high cellulose DP of wood fiber. The as-prepared wood fibers had cellulose DP of 1 998 under conditions， which were molar ratio of choline chloride to lactic acid of 1∶11， reaction temperature of 140 ℃， reaction time of 45 min， water content of 3%， as well as zero-distance tensile strength of 261.9 N·m/g， and the paper made by these fibers also exhibited excellent tensile strength of 51.6 MPa and toughness of 2.0 MJ/m³.

Synthesis and Application of Highly Cationic Starch-based Styrene-acrylate Copolymeric Emulsion for Papermaking

LIU Yi,WANG Lijun,FU Wenhui,JIA Ding,LAI Yifan,MARTIN Ekman,TOM Schauman — 2024/10/8 10:57:12

Soap-free emulsion polymerizations of styrene-acrylate surface sizing agent for papermaking were carried out using styrene （St）， n-butyl acrylate （BA）， and tert-butyl acrylate （tBA） as monomers， H₂O₂-FeSO₄ as initiator， and a series of highly cationic starches （HCS） as emulsifiers. The effects of dosage， molecular weight （characterized by intrinsic viscosity）， and degree of substitution of the HCS on the emulsion polymerization were discussed. A variety of methods were used to evaluate the physical and chemical properties as well as the application performance of the emulsions. The prepared styrene-acrylate emulsion had a small average particle size of colloidal particles （126.2 nm）， and strong positive charge properties （Zeta potential was 25.8 mV） and had excellent storage stability， when it was applied to corrugated base paper， the Cobb value of the sized paper was 21.6 g/m²， and the water droplet contact angle reached 121.6°. A mechanistic explanation for the reason why it could give paper better surface sizing effects was also provided.

Effect of Metal Ion and Non-silicon Stabilizer on the Stability of Hydrogen Peroxide in Chemi-mechanical Pulp Bleaching Process

LIU Xiaoxiao,XIE Qingyu,YANG Lei,ZHA Wangmin,WU Xiaomin — 2024/10/8 10:57:13

The effects of five metal ions （Ca²⁺， Mg²⁺， Fe³⁺， Cu²⁺ ，and Mn²⁺） and six non-silicon stabilizers on residual H₂O₂ content in chemi-mechanical pulp bleaching process were studied. The results showed that Ca²⁺ and Mg²⁺ could increase the residual H₂O₂ content， while Fe³⁺，Cu²⁺， and Mn²⁺ reduced the residual H₂O₂ content significantly. The calcium and iron chelation values of hydroxyethyl diphosphonic acid （HEDP） were the highest in non-silicon stabilizer， with calcium chelation value of 434.0 mg/g and iron chelation value of 243.6 mg/g. Diethylenetriamine pentamethylene phosphonic acid （DTPMP） could effectively inhibit the ineffective decomposition of H₂O₂ in the bleaching process， the residual H₂O₂content was up to 4.0%， and the whiteness of the pulp was 69.9%，when Mn²⁺ mass concentration was 1 mg/kg.

Analysis Method on the Improvement of Appearance Quality of Coated White Cardboard

WANG Chao,YANG Xue,JIA Wenling,HAN Chenxiao,LI Wei,LI Bin — 2024/10/8 10:57:15

This article focused on the study of coated white cardboard， grounded in modern quality management theory， analyzed paper quality issues using analysis tools such as Pareto chart and Fishbone diagram， and clarified that the improvement target for appearance quality was the scraper line. The use of statistical methods and the Minitab tool facilitated a detailed examination of factors potentially causing scraper lines， leading to the proposal of corresponding improvement measures. Ultimately， by refining the production process， the issue of scraper lines was ameliorated. The evaluation of the improvement’s effectiveness in reducing scraper lines confirmed the efficacy of the quality improvement measures taken.

Study on the Morphology and Structural Characteristics of Ten Species of Wild Bamboo Fiber in Guangxi

2024/5/30 14:33:22

The fiber morphology and structure of ten species of wild bamboo in Guangxi （Bambusa textilis， Schizostachyum funghomii， Bambusa pervariabilis， Bambusa grandis， Bambusa Validus， Dendrocalamus sapidus， Dendrocalamus minor var. amoenus， Bambusa surrecta， Schizostachyum auriculatum， Bambusa remotiflora） were studied. The results showed that the fibers of the ten species of wild bamboo were straight and slender， of which the longest fiber was the Dendrocalamus minor var. amoenus （3.19 mm）. The fiber density of ten species of wild bamboo ranged from 1.20 to 1.45 g/cm³. Among them， the density of Bambusa textilis fiber （1.21 g/cm³） was the smallest. The microfibril angles of ten wild bamboo fibers were between 8° and 11°.

Study on the High-consistency Refining Process of Bleached Softwood and Hardwood Mixed Pulps for Tissue Paper Production

CHEN Xuemei,ZHANG Quan,CHEN Linghua,ZHANG Hongjie,ZHANG Xue,CHENG Yun,HOU Leilei — 2024/5/30 14:33:25

The effects of different refining processes on the fiber properties of mixed pulp of bleached softwood pulp and bleached hardwood pulp （mass ratio of 30∶70） and the physical properties of handsheets for tissue paper were investigated by four processes： high-consistency refining on production line （HC pulp）， high-consistency refining on production line + low-consistency refining on lab （HC+LC pulp）， low-consistency refining on production line （LC pulp）， low-consistency refining on lab （lab pulp）. Through these four refining processes， the HC pulp， HC+LC pulp， LC pulp， and lab pulp were obtained， respectively. The results showed that compared with the LC pulp， the HC pulp contained fewer fine fibers， the fiber kink index was more obvious， and the prepared handsheet had better bulk， softness and water absorption. HC+LC pulp had a higher fiber kink index and a lower content of fine fibers than LC pulp. Among them， the tensile index， bulk， softness and water absorption of HC+LC handsheet were better than that of LC handsheet when the pulp concentration of high-consistency refining on production line was 18%， and the tensile index and water absorption of HC+LC handsheet （long fiber ratio of 30%， refining degree 23 °SR） were similar to those of the lab handsheet（long fiber ratio of 35%， refining degree 23 °SR）， with 5.7% higher bulk and 27.6% lower softness.

Study on APMP Pulping Property of De-oiled Camphor Woodchips

2024/5/30 14:33:27

Chemical components of de-oiled camphor woodchips were analyzed. Laboratory and pilot scale trials on APMP pulping properties of de-oiled camphor woodchips were performed.The bleaching property of alkalire H₂O₂ of de-oiled camphor wood APMP pulp was investigated. The results showed that under the conditions of NaOH dosage 60 kg/t pulp， H₂O₂ dosage 50 kg/t pulp， temperature 90 ℃ and pulp consistency 25%， physic strengths of camphor wood APMP pulp were higher than eucalypt APMP pulp， but lower than poplar APMP pulp， however its bleachability was lower than both above. In terms of total COD of wastewater， the APMP pulping process of camphor wood was twice that of poplar wood and eucalyptus wood. As the H₂O₂ dosage of 70 kg/t pulp， camphor pulps could be produced at a brightness level of 75.0% with a yield of 82.5%. Results of pilot trials of camphor woodchips chemimechanical pulping showed that， at the H₂O₂ dosage of 27 kg/t pulp， camphor woodchips APMP pulps were produced with a brightness of 35.9%. Papers were prepared from camphor woodchips APMP pulp at beating degree of 44.0 °SR， with tensile strength of 28.5 N·m/g and bulk of 2.57 cm³/g， which was acceptable as furnish for mid-high grade of packaging papers.

Preparation of Highly Dispersed Aqueous Carbon Fibers

2024/4/22 15:38:59

In this study， chitosan hydrochloride （CHI） and sodium dodecyl sulfate （SDS） were used to prepare modifier （CHI&SDS） that used to impregnate and modify the surface of BMH3 carbon fibers， in order to enhance the dispersing ability of the BMH3 carbon fibers in water. The effects of CHI/SDS mass ratio， mass concentration of CHI&SDS modifier， and fiber length on the dispersibility of modified BMH3 carbon fibers in water were systematically investigated， and the chemical structure and surface wettability of the modified BMH3 carbon fibers were characterized and tested by X-ray photoelectron spectroscopy and dynamic contact angle test. The results showed that the dispersion rate of modified BMH3 carbon fibers with fiber length of 5 mm in water could reach 96.2%， which was 87.5 percentage points higher compared with that of unmodified BMH3 carbon fibers， after modified with a solution of CHI/SDS mass ratio =25∶1 at CHI&SDS modifier mass concentration of 0.15%. The number of oxygen-containing functional groups on the surface of the modified carbon fiber was significantly increased， and the water contact angle was significantly reduced， which was the reason for the improved dispersion of the carbon fiber and the basis for the successful preparation of highly dispersed aqueous carbon fiber.

Research Progress on Machine Applicability of Paper-based Cigarette Packaging Materials

2024/4/22 15:39:01

Paper-based cigarette packaging materials are the important parts of cigarette products. The applicability of it on cigarette machines is directly related to the quality， production efficiency and material cost of cigarette products. This paper analyzed the common problems of 5 types of main paper cigarette packaging materials in the production process of cigarette products， including cigarette paper， tipping paper， inner liner， label paper and inner frame. The studies on the applicability of paper-based cigarette packaging materials on the machine were summarized, to provide reference for cigarette enterprises and paper-based cigarette packaging material manufacturers , and improve the applicability of the materials on the machine.

Study on Preparation and Strength Properties of Corrugated Medium Using Bamboo Pulp and Camphor Residue Pulp

2024/4/22 15:39:03

In this study， the commercially available natural bamboo pulp was sieved， the short-fibre bamboo pulp with partide size<0.6 mm and oil evaporation of camphor residue pulp were selected to prepare corrugated medium. The results showed that when 25% soft wood pulp， 0.5% cationic starch （CS）， 0.4% cationic polyacrylamide （CPAM），and 1.8% polyamide epichlorol resin （PAE， concentration of 9.5%） were added， short-fibre bamboo pulp （unbeaten） and camphor residue pulp were used to prepare paper with the mass ratio of 10∶90 without cure treatmeut， the paper splitting length was 2.66 km， the cyclic compression index was 5.60 N·m/g， which met the requirements for the qualified products of GB/T 13023—2008.When the short-fibre bamboo pulp was beat to a degree of 35.8 °SR， and the camphor residue pulp was added with the mass ratio of 30∶70， after cure treatment 110 ℃ for 15 min， the paper was obtained with splitting length of 4.75 km， cyclic compression index of 8.24 N·m/g，breakage resistance index of 2.80 kPa·m²/g， folding resistance of 15， of which the splitting length and the cyclic compression index reached the requirements for the superior grade of GB/T 13023—2008 ， breakage resistance index and folding resistance indicators were up to the requirements for qualified products of GB/T 13024—2016.

Application Problems and Solutions of Recycled Fiber in Tissue Paper

2024/4/22 15:39:06

Efficient utilization of renewable resources is an important way for ecological civilization. Recycled fiber had received extensive attention in the pulp and paper industry in recent years due to its advantages of low consumption and pollution. This paper briefly described the existing problems and solutions of the of recycled fiber application in tissue paper. The development of recycled fiber in the tissue paper production was also prospected.

Research on Design Analysis for the Core Material for Central Heated Tobacco

ZHANG Wenjun,WU Jianlin,CHEN Yuchao,ZHOU Jun,WANG Xiaosheng,LI Zhongren — 2024/4/22 15:39:08

In order to further investigate the structure and design of core material for central heated tobacco， six kinds of central heated tobacco core materials of Marlboro IQOS brand were selected to analyze the microstructure， physicochemical properties， and inorganic element content of samples. The results showed that core material was composed of a mixed slurry system stacked under certain pressure， with lower average fiber length and width， but higher fine fiber content， percentage of fine fiber area， and fiber coarseness， The cutting width of the core material was 0.5 mm， and the filling density reached 0.615 g/cm³. The content of hot water soluble substances in core material ranged from 61.51% to 67.99%， with an average value of 63.69%. The organic chemical composition of core material was relatively low except for total alkaloids， and the high content of total alkaloids was artificially added. The average ash content of the core material was 9.98%， and inorganic element analysis indicated that it may contain combustion regulators and heat transfer materials containing metal salts such as magnesium and aluminum. Glycerol and propylene glycol were the main smoke generating agents for core material， with an average total amount of 13.79%. The sensory quality of the core material was relatively more dependent on artificially added volatile aroma compounds.

Feasibility Study of Lithium Slag as Filler in Papermaking

2024/2/29 11:22:27

The physical and chemical properties of two types of lithium slag were investigated， and the effect of lithium slag content on paper properties was explored. The results showed that the micro-morphology of lithium slag was irregular gravel-like， with a large internal surface area of the porous structure. The particle size of lithium slag was large and widely distributed. The brightness of 1^# lithium slag and 2^# lithium slag was 66.4% and 76.5%， respectively. The brightness of the paper was reduced after filling the lithium slag. The strength performance of the paper filled with lithium slag was better than the paper filled with PCC. At 18 wt% filler content， the tensile index of the paper filled with 1^# lithium slag was 38% higher than that of the paper filled with PCC. At 12 wt% filler content， the tear index of the paper filled with 2^# lithium slag was 41% higher than that of the paper filled with PCC. In addition， the water resistance of the paper filled with 2^# lithium slag was comparable to that of the paper filled with PCC， which could meet the requirements of water resistance of paper. Therefore， lithium slag could be used in packaging paper with lower whiteness requirements.

Interaction between Printed Cigarette Packet Packaging Paper and Adhesive and Its Influence on Adhesion Strength

2024/2/29 11:22:28

On the basis of analyzing the performance of typical printed cigarette packet packaging paper and cigarette packaging adhesive， the contact angle and width changes of adhesive droplets on the surface of the adhesive area of packet packaging paper were studied， and the effect of adhesive opening time on the adhesion strength was explored. The results showed that when packaging adhesive droplets were added to the surface of packet packaging paper， whether on the printed or non-printed surface， the contact angle continued to decrease and the droplet width continued to increase over time. The time for the two to reach equilibrium was different. The decrease in droplet contact angle was the result of the joint action of expansion and penetration， while the change in droplet width was only related to expansion. Different combinations of packet packaging paper and packaging adhesive had different changes in droplet contact angle and width， as well as different opening time windows for gluing. It was related to the viscosity and solid content of the adhesive， as well as the expansion and permeability of the packet packaging paper. The wettability of water on packet packaging paper was significantly different from that of adhesives， and the wettability of water on the surface of the paper should not be used to determine the behavior of adhesives.

Research Progress on Thermogravimetry and Pyrolysis Behavior and Aerosol Release Characteristics of Heated-not-burn Cigarette Tobacco Material

2024/2/29 11:22:30

Heated-not-burn cigarette tobacco material is the source of nicotine and flavor components. Heat-not-burn reconstituted tobacco is the most commonly used for heated-not-burn cigarette at present， and its production processes mainly include papermaking， dry papermaking， thick pulp， and roll pressing， etc. However， compared with traditional cigarette reprocessed tobacco， there are great differences in physical and chemical properties and sensory quality. The aerosol release characteristics of heated cigarettes， which are smoked by consumers at low temperature， are also significantly different from those of traditional cigarettes. In this paper， the manufacturing process， thermal properties， and aerosol release characteristics of heated-not-burn cigarette material were studied to provide reference for the design， development and quality improvement of heated-not-burn cigarette products.

Effect of Fiber Properties on Water Vapor Barrier Performance of Paper

HU Xiaoli,ZHANG Xue,ZHANG Hongjie,HOU Leilei,CHENG Yun,TIAN Chao — 2024/1/20 0:00:00

In this study， paper with different physicochemical properties were prepared by using different types of pulp fibers with different degrees of pulping treatment and silane modification to regulate the three-dimensional structure of paper. From the viewpoint of the effects of fiber physical properties and chemical hydrophobic modifications on paper structure， the effects of fiber properties （beating degree， fiber length and distribution， water retention value， fiber morphology and hydrophilic/hydrophobic property） on the water vapor barrier performance of paper were investigated. The results showed that the water vapor barrier performance of the paper was influenced by the beating degree and hydrophilic/hydrophobic of the fibers. Under the testing conditions of （23±0.5）℃ and （50±1）%RH， the water vapor transmission rate of the paper with a basis weight of 60 g/m² was reduced from 954.5 to 93.77 g/（m²·d）， when the beating degree of the unbleached pine pulp was increased from 13.5 to 90 °SR. The water vapor transmission rate of the paper prepared by hydrophobic modified fiber was reduced by 11.6% compared with that of unmodified fiber when the test conditions were （23±0.5） ℃ and （75±1）%RH. The water vapor transmission rate of paper was influenced by the mixing proportion of hydrophobic modified fiber.

Study on the Repulping Performance of Monosaccharide or Disaccharide for Paper-based Packaging Materials

KUI Minghong,CHENG Dong,SHEN Chao — 2024/1/20 0:00:00

This paper aimed to achieve a collaborative strategy by changing the types and proportions of barrier coatings and auxiliary materials， in order to construct green flexible packaging materials with good heat sealing， water resistance， oil resistance， and easily repulpable. The results showed that the barrier coating introduced the monosaccharides or disaccharides as auxiliary could significantly improve the recyclability of paper based materials. When the mass fraction of monosaccharides or disaccharides reached 10% （relative to barrier coatings）， more than 90% of paper-based packaging materials could be easily repulped without affecting their performance.

Research Progress on Improving the Purity of Dissolving Pulp

ZHANG Lanhao,YU Dongmei,CHEN Yehong,WU Chaojun — 2024/1/20 0:00:00

Dissolving pulp was a bleached pulp with α-cellulose content higher than 90%， as a raw material for the manufacturing of various cellulose industrial products， was not only an important additive in pharmaceuticals， food， cosmetics， and other industrial fields， but also used to make materials such as mobile phone screens. Therefore， the purity and quality requirements for dissolving pulp were constantly improved. Purification of dissolving pulp through physical and chemical methods to improve α-cellulose content， removal of hemicellulose， lignin carbohydrate （LCC）， and other impurities in dissolving pulp were effective methods to improve the purity of dissolving pulp. This review compared and analyzed the purification methods of dissolving pulp， including biological， chemical， and their combination methods. It also analyzed the mechanisms of various purification technologies， summarized the advantages and disadvantages of each technology in purifying dissolving pulp， and proposed ideas and methods for preparing high-purity dissolving pulp.

Effect of Tobacco Powder Particle Size and Its Distribution on Properties of Slurry-type Reconstituted Tobacco Leaf

2024/1/20 0:00:00

Five groups of cigarette powder with different particle sizes were used to prepare slurry-type reconstituted tobacco leaf （RTL）. The impact characteristics cigarette powder with single mesh size and continuously graded mixed cigarette powder on the properties of slurry and RTL were revealed， the effects of particle size distribution on RTL properties were analyzed， to find out optimal particle size and grading scheme of cigarette powder. The results showed that， as the particle size of tobacco powder decreased， the viscosity of the slurry decreased， and the density and tensile strength of RTL increased. Using small particle size tobacco powder could prepare RTL with better strength but excessively high density. Mixed four particle sizes of tobacco powder from 80 mesh to ≥200 mesh with a grading coefficient of 0.2， the tensile strength and thickness of RTL were suitable. Comparing tobacco powder with the same average particle size but different size distribution， a wider particle size distribution was more conducive to the strength property of RTL. Taking into account the properties of slurry and RTL， the optimal mixing conditions for tobacco powder were as follows： the proportion of four particle sizes of tobacco powder from 80 to ≥200 mesh was 32.2%， 13.0%， 12.8%， and 42.0%， respectively， the density was 0.72 g/cm³， and the tensile strength was 0.549 kN/m.

Study on the Effect of Tobacco Powder Addition on Solid-Liquid Coupling Coating of Reconstituted Tobaceo

ZHAO Jintao,LIN Yu,ZHANG Yunlong,ZHANG Linlin,DONG Gaofeng,HE Liang,PENG Lincai — 2024/1/20 0:00:00

In order to investigate the effect of tobacco powder addition on the coating effect of solid-liquid coupling， this study mainly discussed the effects of tobacco powder addition on coating effect and physical and chemical indexes of reconstituted tobacco through the analysis of tobacco powder properties. The results showed that the addition of tobacco powder led to an increase in density， solid content， and viscosity of the coating solution， and the viscosity increased the fastest， and the dosage affected the coating solution more than the particle size. The addition of tobacco powder caused an increase in tensile strength and a decrease in softness and air permeability of the reconstituted tobacco leaves. The appropriate proportion of added tobacco powder should be less than 9%， and the particle size was about 500 mesh.

Research on Improving the Performances of Recycled Fibers with Mechanically Refining of Chemical Pulp

2024/12/23 9:07:49

The bleached kraft hardwood pulp was used to simulate the paper recycling process， and the PFI refining was used to study its effects on the recycled fiber properties and the physical properties of resulted paper. The results showed that mechanically refining treatment during fiber recycling could significantly improve the performances of fibers and their papers. Compared with fibers without mechanically refining treatment， the decrease in water retention value and degree of hornification of fibers after mechanically refining treatment were reduced. The tensile index， tearing index， and bursting index of paper were increased， respectively. The specific surface area， average pore volume， and pore size of fibers were higher than those without mechanically refining treatment. Moreover， after being recycled for six times， the fibers treated with mechanically refining still retained more fine fibers on their surface， resulting good bonding between the fibers.

Effects of Transition Metal Ions in Raw Materials on the Bleachability of Chemical Mechanical Pulps

2024/12/23 9:07:50

In this study， three kinds of eucalyptus woods and three kinds of poplar woods， which were mainly used in the production of chemical mechanical pulp， were compared with the difference of transition metal ion content in the pulp and the pre-impregnated residues. The effects of transition metal ions in the pulp on the bleachability and the effects of metal ions in the pre-impregnated residues on oxidation resistance were analyzed. The results showed that high contents of Mn²⁺ in eucalyptus and the high contents of Fe³⁺ in poplar resulted in poor bleachability of the pulp. The high contents of Fe³⁺ in eucalyptus and poplar pre-impregnated residues led to the strong antioxidant properties， which resulted in high chemical consumption in actual production. For the completely removal of pre-impregnated residues， increasing the dosage of chelating agent had no significant effect on the bleachability of poplar， but had certain improvement on the bleachability of eucalyptus. For fully retained pre-impregnated residues， increasing the dosage of chelating agent had more obvious improvement on the bleachability than increasing the dosage of hydrogen peroxide.

Research on the Improvement of Papermaking Performance of Wikstroemia delavayi Lecomte Bark by Bio-enzymes

XU Qiao,ZHANG Chunhui,LIU Yanping — 2024/11/22 15:48:30

This study used pectinase， hemicellulase， pectinesterase， and a composite enzyme composed of these enzymes to pretreat the raw materials of Wikstroemia delavayi Lecomte bark. The removal effect of the biocatalyst on non-fiber substances was evaluated by reducing sugar content， and the effects of different bio-enzymes on the papermaking performance of Wikstroemia delavayi Lecomte bark were evaluated by testing some indices such as the pulp yield， Kappa value， and physical properties of the paper. The results showed that the D₁ enzyme compounded by pectinase（10 mL）， hemicellulase（10 mg）， and pectinesterase（10 mL） had the best removal effect， and the reducing sugar content of the D₁ enzyme pretreatment solution was 7.4%. The Kappa value of the pulp obtained from cooking after D₁ enzyme pretreatment decreased by 5.3% and the whiteness of paper increased by 10.3% compared with the control sample A₀. The D₁ enzyme pretreated 20 days and non-enzymatic pretreated raw materials were cooked at 5% and 6% K₂CO₃ （in Na₂O）， respectively， and folding endurance， tensile index， and tear index of the pretreated papers were increased by 30.3%， 14.8%， and 11.2%， respectively， which indicated that the bio-enzymatic pretreatment was able to reduce the amount of chemicals used in the cooking process and improve the physical properties of the paper.

Annealing Treatment Assisted Amylase Hydrolysis for Preparation of Surface Sizing Starch and Its Impact on Mechanical Properties of Paper

WU Zikun,LIU Liqin,LU Bin,CHENG Zhengbai,LYU Xiaofeng,CAO Haibing,AN Xingye — 2024/11/22 15:48:32

In this study， corn starch was first subjected to the annealing treatment， and then the surface-sized starch was prepared by amylase hydrolysis method. This study specifically discussed the physicochemical properties of modified starch and its impact on the mechanical properties of paper. The results showed that annealing treatment could significantly regulate the content of amylose and the crystalline structure of starch. Compared with corn starch， the surface-sized starch prepared from annealed 75% moisture content，60 ℃ for 24 h could effectively improve the mechanical property of paper， with a maximum increase of approximately 3.7% in ring crush index， 10.5% in transverse tensile index， 3.4% in longitudinal tensile index， and 10% in burst index. The innovative research results provided a deep understanding of the enhanced mechanism of surface-sized starch on the mechanical properties of paper in terms of short-range order， which provided theoretical basis and technical support for the preparation of surface-sized starch assisted by annealing treatment.