99results about "Pulping with halogen compounds" patented technology

An omnibus process of pulping and bleaching lignocellulosic materials in which a charge of a lignocellulosic material is biopulped and/or water extracted prior to pulping and bleaching. The lignocellulosic material may be mechanically pulped and bleached in the presence of an enzyme that breaks lignin-carbohydrate complexes. The aqueous extract in embodiments including a water extract step is separated into acetic acid and hemicellulose sugar aqueous solutions.

The present invention discloses methods of bleaching chemical pulp that combine xylanase enzymes with hydrogen peroxide, peracids, or a mixture. The method comprises the steps of carrying out a chemical pulping operation, optionally followed by delignifying the pulp with oxygen, then combining xylanase enzymes with hydrogen peroxide, peracids, or a mixture to bleach the pulp. The method allows the mill to use both xylanase and peracids in a single bleaching tower to decrease the usage of chlorine dioxide and other bleaching chemicals. The pulp bleaching method of the present invention may be performed in a pulp mill as part of a complex pulp bleaching process.

Oxidative compositions and processes that preserve and enhance the brightness and improve color of pulp or paper when applied during different stages of the papermaking process are identified. The oxidative composition and method maintains and/or enhances brightness, prevents yellowing, and enhances the performance of paper products. Used in combination with optical brighteners and/or chelants the oxidative agents produce a synergistic effect not previously identified in the paper process.

A high pH and a low pH process for reducing the degree of polymerization of a pulp having a hemicellulose content of at least 7%. The high pH is greater than 8, and the low pH process is 2 to 8. The high pH process reduces the degree of polymerization without substantially increasing the copper number. The low pH process requires a subsequent treatment with alkali to reduce the copper number of the pulp to less than 2. The process can be practiced in pulp mills with a bleaching sequence having one or more E or D stages. At the end of the bleach sequence, a pulp having a degree of polymerization of 200 to 1100, a copper number of less than 2, and a hemicellulose content of at least 7% is provided. The pulp can be used to make lyocell fibers.

This invention provides a process for treating chemical woodpulp, or chemical cellulose including cotton linter, including the step of applying an electron processing technology (EPT) step to chemical woodpulp, or chemical cellulose, as the case may be, on an in-line basis to provide control of pulp viscosity or degree of polymerisation (DP). The invention also provides a method of process control in treating the aforementioned woodpulp or cellulose, including the step of using radiation dose-viscosity relationship curve for applying an EPT step on an in-line basis. The in-line EPT step may, in one form of the invention, replace and hence eliminate a chemical DP reduction step.

Described herein are processes for the production of a cellulose pulp and processes for isolating cellulose from cellulose-containing biomass. The processes of the invention comprises contacting the biomass with a source of anions and a source of cations, the source of anions and the source of cations being selected to react exothermically with the biomass and with each other. The processes of the invention have the particularity of generating exothermic reactions through enthalpies of reaction and mixture. Accordingly, the processes of the invention do not require any supply of external energy since the required energy is provided by chemical reagents that are already present in the biomass or added as needed. The invention also relates to isolated cellulose obtained from these processes and the use of same in various materials.

The invention discloses a method for manufacturing nanofiber transparent paper from straw, belonging to the field of papermaking. According to the invention, with adoption of oxidized fiber of a 1,3-dihydroxyacetone oxidization system, the electrostatic repulsive force among nano-cellulose is enhanced, so that the cellulose can be separated from cell walls completely, and the transparent paper has higher transparency and excellent mechanical strength. Sodium hypochlorite can be used as an oxidizing agent, has a bleaching function due to strong oxidizing property, and can react with little lignin left in original fiber to remove the lignin so as to improve light transmission. The raw materials are readily available, and the transparent paper is biologically degradable and cheap.

The invention relates to a method of bleaching cellulose pulp in a bleach line having at least two bleaching steps D1, D2 of alkaline or acidic type, and a bleaching line for the method, in which the filtrate distribution is led up through the bleaching line in counter-current to the flow of cellulose pulp established in the bleaching line. Instead of a conventional filtrate distribution including filtrate tanks, a single joint main conduit 1 is used for the bleaching steps of the same type. Wash filtrate obtained from the wash steps of the same type used after or before the bleaching step, is led to a branch point A2, A4, A6 on the main conduit 1, that is positioned after the branch point for drawing off of wash and/or dilution liquor for the wash step in question A1, A3, A5, A7. All branch points in the joint main conduit are in open communication with each other in the main conduit, at least as seen in a direction from the last bleaching step. Hereby, a simplified and improved filtrate distribution system with an improved runnability is obtained.

A method of bleaching chemical pulp with xylanase after chemical bleaching is provided. The method comprises the steps of exposing chemical pulp to a chlorine dioxide bleaching stage to produce a partially bleached pulp, treating the partially bleached pulp with a xylanase in an enzyme treatment stage at a pH of about 3 to about 8, then carrying out an alkaline extraction of the pulp. The pulp bleaching method of the present invention may be performed in a pulp mill as part of a complex pulp bleaching process.

The invention discloses a method for utilizing straw and waste paper pulp to prepare high strength corrugated base paper, and relates to the field of utilizing cellulose to make paper. After the strawis dried, straw husk is removed to separate out straw medulla, the straw medulla is pulverized, the straw medulla powder is mixed with a NaOH and/or KOH solution of which the mass concentration is 1-10% till the mass concentration of the material is 0.5-5%, after being soaked, the material is washed to be neutral, and water is added to obtain straw medulla pulp, wherein the concentration of the straw medulla is 0.5-5%; then peroxyacetic acid is added into the straw medulla pulp till the mass concentration of peroxyacetic acid is 1-8%, or a hydrochloric acid solution is added into the straw medulla pulp to adjust the pH value of the straw medulla pulp to be 2 or below, then chlorine dioxide is added till the mass concentration of chlorine dioxide in the straw medulla pulp is 1-8%; then thestraw medulla pulp is stirred or oscillated, after being washed to be neutral, the straw medulla pulp is mixed with the waste paper pulp, the mass percentage of the straw medulla in mixed paper pulpis 10-30%, and the mixed paper pulp is utilized to make the corrugated base paper.

Process for bleaching of pulps following cooking of the lignocellulosic material with soda and anthraquinone. The process may produce a whiteness on par with the bleaching of kraft pulp when using a similar bleaching sequence. In some instances, the bleaching sequence may be O-A-Do-Eop-D, O-A-ZDo-Eop-D, A-Do, or A-ZDO.