Pulp fiber containing little ash is effectively recovered from a used sanitary product containing the pulp fiber and a polymer absorbent. The method according to the present invention comprises: a step for treating the used sanitary product with an ozone-containing gas and thus decomposing and removing at least a portion of the polymer absorbent in the used sanitary product; and a step for stirring the used sanitary product, that has been treated with the ozone-containing gas, in water or an aqueous solution containing an antiseptic and thus decomposing the used sanitary product into constituents. If required, the method may further comprise a step for separating the pulp fiber from the decomposition product obtained by the decomposition step.

A feedstock includes feedstock paper and non-paper material. The feedstock paper includes lignin and cellulose. A method includes cooking the feedstock in cooking liquor to dissolve at least a portion of the lignin from the feedstock paper and to at least partially dissolve the non-paper material in the cooking liquor, thereby yielding a cooked pulp. The method further includes washing the cooked pulp to yield washed pulp and spent cooking liquor, regenerating the spent cooking liquor to yield regenerated cooking liquor, and bleaching the washed pulp.

The invention relates to the use of polyesters for increasing the surface tension and improving the hydrophilic behavior of hydrophobic surfaces, wherein said polyesters are obtainable by polymerization of a) one or more unsulfonated aromatic dicarboxylic acids and/or salts thereof and/or anhydrides thereof and/or esters thereof, and b) ethylene glycol, c) 1,2-propylene glycol, and d) one or more polyalkylene glycols, and e) one or more compounds of formula (1)
R.sup.1O(CHR.sup.2CHR.sup.3O).sub.nH  (1) where R.sup.1 is a linear or branched, saturated or unsaturated alkyl group of 1 to 22 carbon atoms, preferably methyl, R.sup.2 and R.sup.3 are each independently hydrogen or an alkyl group of 1 to 4 carbon atoms, preferably hydrogen and/or methyl, and n is from 1 to 50, f) in the presence or absence of one or more crosslinking compounds having 3 to 6 functions capable of polycondensation, especially acid, alcohol or ester functions,
with the proviso that said components d) are used in weight quantities <80%, based on the weight quantity of the polyesters obtained by the polymerization.

The present invention involves an environmentally friendly process and apparatus for the delignification of lignin-containing materials, such as cardboard newspaper or agricultural or tree pruning wastes. This process produces cellulose using low temperatures and low concentrations of hydrogen peroxide. It can be performed using a column fitted with a semipermeable gasket that pressurizes the column by retaining oxygen released by action of the hydrogen peroxide on a lignin-containing material.

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 invention related to an apparatus for recycling of lignocellulosic fibres from a fibreboard comprising compressed lignocellulosic fibres bonded together by a binding agent. The apparatus comprises a transport device arranged within a closed housing, wherein the housing is arranged for steaming pieces of the fibreboard at super-atmospheric pressure to decompress and release the lignocellulosic fibres by hydrating them, as well as hydrolysing the binding agent, and the transport device is arranged for transporting the fibreboard pieces, upon being steamed, from an inlet of the housing, at which the fibreboard pieces are fed to the housing, to an outlet of the housing, at which steamed portions comprising released lignocellulosic fibres exit the housing. Further, the apparatus comprises a steam generator in communication with the housing, whereby the fibreboard pieces may be steamed at super-atmospheric pressure in the housing to provide the steamed portions comprising released lignocellulosic fibres, an inlet pressure lock configured to receive the fibreboard pieces at atmospheric pressure and to deliver them to the housing, via the inlet, at super-atmospheric pressure, and an outlet pressure lock configured to receive steamed portions comprising released lignocellulosic fibres via the outlet and ejecting recycled lignocellulosic fibres during a sudden expansion of super-atmospheric pressure.

The purpose of the present disclosure is to provide a method for producing pulp fibres for saccharification from the pulp fibres of used sanitary items, said pulp fibres for saccharification having low lignin contents distributed within a narrow range, and enabling the production of pulp fibres for saccharification having superior saccharification properties. The production method according to the present disclosure is characterised by comprising the following: a step for supplying a mixed solution (51) containing pulp fibres and highly-absorbent polymers sourced from used sanitary items to a treatment tank (31) via a mixed-solution supply port (32); a step for supplying an ozone-containing gas (53) to a treatment solution (52) within the treatment tank (31) via an ozone-containing-gas supply port (43); a step for lifting the ozone-containing gas (53) whilst lowering the pulp fibres and highly-absorbent polymers within the treatment tank (31), thereby bringing the ozone-containing gas (53) into contact with the pulp fibres and highly-absorbent polymers, and forming pulp fibres for saccharification from the pulp fibres; and a step for discharging the treatment solution (52) via a treatment-solution discharge port (33). The method is further characterised in that the pulp fibres for saccharification have lignin contents of 0.1% or less.

The purpose of the present invention is to provide a method for producing recycled pulp fibers such that articles using the recycled pulp fibers can easily achieve a uniform whiteness and users are not prone to feel psychological resistance to articles using the recycled pulp fibers. This method is described below. The method is characterized by involving: a step for supplying, from a mixed solution supply port (32) to a treatment tank (31), a mixed solution (51) which contains superabsorbent polymers and pulp fibers derived from multiple types of used sanitary products; a step for supplying an ozone-containing gas (53) from an ozone-containing gas supply port (43) to a treatment solution (52) inside of the treatment tank (31); a step in which, by raising the ozone-containing gas (53) while lowering the superabsorbent polymers and pulp fibers in the treatment tank (31), the ozone-containing gas (53) is brought into contact with the superabsorbent polymers and the pulp fibers, and the pulp fibers are bleached to form recycled pulp fibers; and a step for discharging the treatment solution (52) from a treatment solution discharge port (33), wherein the recycled pulp fibers have a 0-10 ΔYI with respect to a standard white plate.

The objective of the present disclosure is to provide a method for easily evaluating the degree of cleanliness of recycled material derived from used sanitary products. The evaluation method according to the present disclosure has the following configuration. This method for evaluating a degree of cleanliness of recycled material derived from used sanitary products includes: a preparation step of preparing a dispersed aqueous solution in which the recycled material is dispersed in water; a separation step of subjecting the dispersed aqueous solution to centrifugal separation to separate the dispersed aqueous solution into a liquid component and a solid component; and a measuring step of measuring the concentration of protein in the liquid component using a protein measuring means.

Removal of stickies from waste paper and paperboard is obtained with the use of a modified kaolin-based stickies removal composition. The modified kaolin-based stickies removal composition is produced by modifying the kaolin clay, separating the modified kaolin clay from the non-reactive kaolin clay, and then adding a nonionic surfactant to the modified kaolin-based particles. Removal of stickies is improved by the use of this modified kaolin-based stickies removal composition during the recycling of the waste paper and paperboard.