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Use of fines-enriched chemical pulp to increase CTMP strength, TAPPI Journal April 2021
ABSTRACT: In this study, fines-enriched pulp (FE-pulp)—the fine fraction of highly-refined kraft pulp—was benchmarked against highly-refined kraft pulp (HRK-pulp) as a strength agent in eucalyptus chemithermomechanical pulp (CTMP). Both the FE-pulp and the HRK-pulp were produced from unbleached softwood kraft pulp, and equal amounts of those strength agents were added to the original CTMP, as well as to washed CTMP, where most of the fines had been removed. The effects of the added strength agents were evaluated with laboratory handsheets.The FE-pulp proved to be twice as effective as HRK-pulp. Both HRK-pulp and FE-pulp increased the strength of the CTMP handsheets. The bulk of the handsheets decreased, however, as well as the drainability. The addition of 5% FE-pulp resulted in the same strength increase as an addition of 10% HRK-pulp, as well as the same decrease in bulk and CSF. For the handsheets of washed CTMP, the strengths were not measurable; the CTMP lost the sheet strength when the CTMP-fines content was reduced through washing. The reduced strength properties were compensated for by the addition of chemical pulp fines that proved to be an efficient strength agent. The addition of 5% FE-pulp restored the strength values, and at a higher bulk and higher drainability.
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Formic acid pulping process of rice straw for manufacturing of cellulosic fibers with silica, TAPPI Journal August 2021
ABSTRACT: Emerging technology has the potential to develop entirely new approaches for producing cellulose fiber-based materials along with fuels and chemical raw materials like lignin and furfural. Rice straw is a rich source of cellulosic fibers and inorganic micronic-sized particles termed as ash. They can prove helpful in development of new or enhanced agricultural residue-based materials and products that offer cost effective substitutes for nonrenewable materials used in different domestic and industrial applications. Lignocellulose is an abundant material that is submicronic at the basic level. Rice straw is a fibrous lignocellulosic material obtained as agricultural residue, but it differs from most crop residues in its high content of silicon dioxide (SiO2). Ash content on a dry weight basis ranges from 13% to 20%, varying according to the state of conservation of the straw after harvest. The ash in rice straw has nearly 75% SiO2. The particle size analysis shows variation from a few microns to hundreds of microns for inorganic residues left after burning at high temperatures above 550°C. Proximate analysis of rice straw shows that it contains 54% to 56% holocellulose and 15% to 18% lignin, both of which are natural biopolymers. The compound analysis shows the different compounds present in rice straw ash.Rice straw is available in hundreds of million tons in India and other Asian countries, so suitable technologies are required to convert rice straw from a biomass waste to useful bioproducts like pulp, paper, and paperboard. This research paper is intended to obtain pulp with fibers having inherent silica present in it to give high opacity paper and better bonding between fibers.
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Technological evaluation of Pinus maximinoi wood for industrial use in kraft pulp production, TAPPI Journal August 2021
ABSTRACT: This study characterized Pinus maximinoi wood and evaluated its performance for pulp production. Samples of Pinus taeda wood were used as reference material. For both species, wood chips from 14-year-old trees were used for the technological characterization, pulping, bleaching process analysis, and pulp properties. A modified kraft pulping process was carried out targeting kappa number 28±5% on brownstock pulp. The bleaching sequence was applied for bleached pulp with final brightness of 87±1 % ISO. Refinability and resistance properties were measured in the bleached pulps. Compared to P. taeda wood, P. maximinoi showed slightly higher basic density (0.399 g/cm³) and higher holocellulose (64.5%), lignin (31.1%), and extractives content (4.5%), along with lower ash content (0.16%). P. maximinoi tracheids showed greater wall thickness (6.4 µm) when compared to P. taeda tracheids. For the same kappa number, P. maximinoi and P. taeda resulted in similar screened yield, with an advantage observed for P. maximinoi, which resulted in lower specific wood consumption (5.281 m³/o.d. metric ton), and lower black liquor solids (1.613 metric tons/o.d. metric ton). After oxygen delignification, P. maximinoi pulp showed higher efficiency on kappa reduction (67.2%) and similar bleaching chemical demand as P. taeda pulp. Compared to P. taeda pulps, the refined P. maximinoi pulps had similar results and the bulk property was 10% higher. Results showed that P. maximinoi is an interesting alternative raw material for softwood pulp production in Brazil.
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Can carbon capture be a new revenue opportunity for the pulp and paper sector?, TAPPI Journal August 2021
ABSTRACT: Transition towards carbon neutrality will require application of negative carbon emission technologies (NETs). This creates a new opportunity for the industry in the near future. The pulp and paper industry already utilizes vast amounts of biomass and produces large amounts of biogenic carbon dioxide. The industry is well poised for the use of bioenergy with carbon capture and storage (BECCS), which is considered as one of the key NETs. If the captured carbon dioxide can be used to manufacture green fuels to replace fossil ones, then this will generate a huge additional market where pulp and paper mills are on the front line. The objective of this study is to evaluate future trends and policies affecting the pulp and paper industry and to describe how a carbon neutral or carbon negative pulp and paper production process can be viable. Such policies include, as examples, price of carbon dioxide allowances or support for green fuel production and BECCS implementation. It is known that profitability differs depending on mill type, performance, energy efficiency, or carbon dioxide intensity. The results give fresh understanding on the potential for investing in negative emission technologies. Carbon capture or green fuel production can be economical with an emission trade system, depending on electricity price, green fuel price, negative emission credit, and a mill’s emission profile. However, feasibility does not seem to evidently correlate with the performance, technical age, or the measured efficiency of the mill.
Magazine articles
Deinking Difficulties Related to Ink Formulation, Printing P
Deinking Difficulties Related to Ink Formulation, Printing Process and Type of Paper
Journal articles
Magazine articles
Predicting strength characteristics of paper in real time using process parameters, TAPPI Journal March 2022
ABSTRACT: Online paper strength testing methods are currently unavailable, and papermakers have to wait for manufacture of a complete reel to assess quality. The current methodology is to test a very small sample of data (less than 0.005%) of the reel to confirm that the paper meets the specifications. This paper attempts to predict paper properties on a running paper machine so that papermakers can see the test values predicted in real time while changing various process parameters. This study was conducted at a recycled containerboard mill in Chicago using the multivariate analysis method. The program provided by Braincube was used to identify all parameters that affect strength characteristics. Nearly 1600 parameters were analyzed using a regression model to identify the major parameters that can help to predict sheet strength characteristics. The coefficients from the regression model were used with real-time data to predict sheet strength characteristics. Comparing the prediction with test results showed good correlation (95% in some cases). The process parameters identified related well to the papermaking process, thereby validating the model. If this method is used, it may be possible to predict various elastic moduli (E11, E12, E22, etc.) in the future as the next step, rather than the traditional single number “strength” tests used in the containerboard industry, such as ring crush test (RCT), corrugating medium test (CMT), and short-span compression strength test.
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Tetraethyl orthosilicate-containing dispersion coating — water vapor and liquid water barrier properties, TAPPI Journal September 2021
ABSTRACT: An aqueous styrene-butadiene latex dispersion coating containing in-situ processed tetraethyl orthosilicate (TEOS) applied on paperboard demonstrated improved water barrier performance. Coatings containing TEOS equivalent to 0.8% silicon dioxide (SiO2; dry basis) exhibited water vapor performance of < 25 g/m2/day (23°C, 50% relative humidity [RH]) and liquid water barrier performance Cobb 1800 s of < 6 g/m2, when applied as a single-layer 18 g/m2 coating. Cobb 1800 s barrier performance was still good (< 11 g/m2) at coat weights of 7–10 g/m2. The use of filler materials such as kaolin improved the vapor barrier properties of the coating, but this was not critical to the liquid water barrier properties.
Journal articles
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Effects of phosphogypsum whiskers modification with calcium stearate and their impacts on properties of bleached softwood paper sheets, TAPPI Journal September 2021
ABSTRACT: By combining the structural properties and characteristics of phosphogypsum whiskers, a preliminary study on the modification of phosphogypsum whiskers and their application in papermaking was carried out. The effects of reaction temperature, reaction time, and reaction concentration on the solubility and retention of modified phosphogypsum whiskers and the effects of phosphogypsum whiskers on the physical properties of paper under different modified conditions were explored. The research results show that, after the phosphogypsum whiskers are modified with calcium stearate, a coating layer will be formed on the surface of the whiskers, which effectively reduces the solubility of the phosphogypsum whiskers. The best modification conditions are: the amount of calcium stearate relative to the absolute dry mass of the phosphogypsum whisker is 2.00%; the modification time is 30 min, and the modification temperature is 60°C. The use of modified phosphogypsum whiskers for paper filling will slightly reduce the whiteness, folding resistance, burst resistance, and tensile strength of the paper, but the tearing degree and retention of the filler will be increased to some extent.
Journal articles
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A guide to eliminating baggy webs, TAPPI Journal June 2021
ABSTRACT: Slack or baggy webs can cause misregistration, wrinkles, and breaks in printing and converting operations. Bagginess appears as non-uniform tautness in the cross direction (CD) of a paper web. The underlying cause is uneven CD tension profiles, for which there are few remedies once the paper is made. Precision measurements of CD tension profiles combined with trials on commercial paper machines have shown that uniform CD distribution of moisture, basis weight, and caliper profiles at the reel are key to avoiding bagginess. However, the most important but infrequently measured factor is the CD moisture profile entering the dryer section. Wetter areas entering the dryers are permanently elongated more than dry areas, leading to greater slackness in the finished paper. In storage, wound-in tension can amplify baggy streaks in paper near the surface of a roll and adjacent to the core. Unwrapped or poorly wrapped rolls exposed to low humidity environments may have baggy centers caused by moisture loss from the roll edges.All of the factors that impact bagginess have been incorporated in a mathematical model that was used to interpret the observations from commercial trials and can be used as a guide to solve future problems.
Journal articles
Magazine articles
Guest Editorial: Research and development in the post COVID-19 era, TAPPI Journal June 2021
Science and technology occupy prominent roles in solving global problems. The ongoing COVID-19 pandemic has reinforced the importance of science regarding decision-making, saving lives, and safeguarding the environment. While information technology (IT) and IT-based tools have garnered much needed attention in the past few decades, other areas such as manufacturing engineering, biotechnology, and pharmaceuticals are finding their right places in gaining public and political support and attention--thanks to COVID-19! Such public attention has highlighted vulnerabilities due to lack of investments in manufacturing and materials engineering, as well as the need for strategic investments in these areas.