There is provided a cellulose based fiber made of a i) cellulose dissolving pulp, and ii) a recycled cellulose textile, which is treated to swell the cellulose with a reducing additive and a) bleached with oxygen at alkaline conditions with a pH in the range 9-13.5 and/or b) bleached with ozone at acid conditions below pH 6, wherein the cellulose based fiber is manufactured with one selected from a Viscose process and a Lyocell process. Advantages include that the tensile strength of the fiber is improved and it is possible to manufacture improved cellulose fibers which comprise a fraction of recycled material.

There is provided a cellulose based fiber made of a i) cellulose dissolving pulp, and ii) a recycled cellulose textile, which is treated to swell the cellulose with a reducing additive and a) bleached with oxygen at alkaline conditions with a pH in the range 9-13.5 and/or b) bleached with ozone at acid conditions below pH 6, wherein the cellulose based fiber is manufactured with one selected from a Viscose process and a Lyocell process. Advantages include that the tensile strength of the fiber is improved and it is possible to manufacture improved cellulose fibers which comprise a fraction of recycled material.

Provided is a method for producing pulp fibers to be saccharified, whereby it becomes possible to reduce the amount of a highly water-absorbable polymer and therefore increase the collection efficiency in the production of a saccharified solution when pulp fibers for a saccharified liquid is produced from a dirty absorbent article. The method is a method for producing pulp fibers to be saccharified, from pulp fibers in a dirty absorbent article. The method includes: a solid-liquid separation step (S18) of crushing up a highly water-absorbable polymer while separating an inactivated aqueous solution containing pulp fibers and the highly water-absorbable polymer both separated from a dirty absorbent article into a solid material (98) containing the pulp fibers and the highly water-absorbable polymer and a liquid material (E) containing the highly water-absorbable polymer and the inactivated aqueous solution; and a removal step (S21) of washing away the remaining highly water-absorbable polymer by washing the separated solid pulp fibers in a solution or another means to produce pulp fibers to be saccharified.

A method of producing conifer-derived pulp fibers for paper includes a beating step of beating conifer-derived material pulp fibers in the presence of a liquid including water; and an ozone treatment step of treating, with ozone water, the beaten conifer-derived material pulp fibers.

The invention relates to a method for bleaching pulp formed from recycled textile material comprising cellulose, said method comprising ozone bleaching (3; 13a, 13b) of said pulp by means of adding ozone at a charge of at least 12 kg/odt, wherein said ozone bleaching (13a, 13b) is performed as two subsequent steps, each comprising adding ozone at a charge such that the overall charge is at least 12 kg/odt.

The invention relates to a method for bleaching pulp formed from recycled textile material comprising cellulose, said method comprising ozone bleaching (3; 13a, 13b) of said pulp by means of adding ozone at a charge of at least 12 kg/odt, wherein said ozone bleaching (13a, 13b) is performed as two subsequent steps, each comprising adding ozone at a charge such that the overall charge is at least 12 kg/odt.

The present invention provides a method which, in the process of manufacturing recycled pulp fibers from a mixture of pulp fibers and a high water-absorption polymer, enables efficient manufacturing of the recycled pulp fibers while properly removing the high water-absorption polymer from the pulp fibers. This method comprises: a supply step (S19-2a) for supplying an aqueous solution containing a mixture (98) to a driving fluid supply port (DI) of an ejector (107) and simultaneously supplying, to a suction fluid supply port (AI) of the ejector, a gaseous substance (Z2) which is capable of degrading a high water-absorption polymer so as to make the degraded polymer dissolvable; and a treatment step (S19-2b) for discharging, from a mixed fluid discharge port (CO) of the ejector that is connected to a lower part of a treatment tank (105), a mixed liquid, which is formed when the aqueous solution and the gaseous substance are mixed within the ejector, into a treatment liquid (P2) within the treatment tank, so as to lessen the high water-absorption polymer in the mixture.

A recycled pulp that is reusable sanitary products is efficiently manufactured by recovering pulp fiber from used sanitary products containing the pulp fiber and a polymer absorbent. The method of the present invention comprises: a step applying a mechanical force to the used sanitary products in an aqueous solution containing a polyvalent metal ion or an acidic aqueous solution with a pH of 2.5 or lower and thus degrading the used sanitary products into the pulp fiber and other materials; a step separating the pulp fiber from the mixture of the pulp fiber and other materials that has been formed in the degradation step; and a step treating the pulp fiber thus separated with an ozone-containing aqueous solution with a pH of 2.5 or lower.

A recycled pulp that is reusable sanitary products is efficiently manufactured by recovering pulp fiber from used sanitary products containing the pulp fiber and a polymer absorbent. The method of the present invention comprises: a step applying a mechanical force to the used sanitary products in an aqueous solution containing a polyvalent metal ion or an acidic aqueous solution with a pH of 2.5 or lower and thus degrading the used sanitary products into the pulp fiber and other materials; a step separating the pulp fiber from the mixture of the pulp fiber and other materials that has been formed in the degradation step; and a step treating the pulp fiber thus separated with an ozone-containing aqueous solution with a pH of 2.5 or lower.

The application relates to a method for preparing dissolving pulp by totally chlorine-free bleaching of poplar kraft pulp, including: preparing poplar kraft pulp by pre-hydrolysis kraft process with poplar as raw material; ZOQP bleaching of poplar kraft pulp to obtain dissolving pulp, wherein Z denotes ozone bleaching, O denotes oxy delignification, Q denotes chelation treatment, and P denotes hydrogen peroxide bleaching. In this way, washing and bleaching wastewater can be recycled in entire preparation process described above, achieving zero discharge. The dissolving pulp prepared by the method has no residual toxic substances, and exhibits that all indexes exceed the requirements of qualified products in dissolving pulp industry standard (QB/T 4898-2015), and most of indexes meet those of excellent products; thus, it can replace imported dissolving pulp. The use of the method significantly solved the problems of large pollution in the production and shortage of raw materials for viscose fibers.