PULP COMPOSITIONS

**Definition:** This place covers:

Pulp compositions and preparation thereof including after-treatment not covered by subclasses D21B , D21C , D21D : (a) from cellulose or lignocellulose fibres of natural origin, (b) from synthetic cellulose or non-cellulose fibres or web-forming material, or (c) non-fibrous material added to the pulp.

Coated paper characterised by: (a) coating material, (b) paper substrate, or (c) comprising more than one coating.

Processes or apparatus for adding material to the pulp or to the paper (processes for making continuous lengths of paper D21F11/00 ).

Treatment of finished paper not covered by class B31 or subclass D21G .

Special paper not otherwise provided for, i.e. paper with special properties or applications which are only partially or not at all provided for elsewhere in the classification, e.g. made by multi-step processes. Whenever possible, however, these papers are classified according to the criteria used in the other groups of this subclass.

Paper-impregnating material characterised by its constitution.

**Glossary:** - binder or binding agent: usually a macromolecular product used to bind the paper-making fibres together in order to give cohesion to the final paper sheet, e.g. starchy materials, latexes, etc. - coating: layer of material applied to the paper substrate. Although part of this material may penetrate through the substrate, a coated paper is characterised by the presence of said layer on its surface. - fibres: under paper-making fibres are meant short fibres (maximum length in the range of the mm). Papers also comprising long fibres or filaments are classified in D21H15/00 . - filler or pigment: usually designating fine particles added to the pulp (very often inorganic materials such as talc, kaolin, silica, calcium carbonate, etc.). - finished paper: paper after passing to the finishing process, creating a surface characteristic of a sheet created by either on-machine or off-machine papermaking processes. Popular text and cover finishes include smooth, vellum, felt, laid, and linen. - impregnation: application of a liquid material to a paper substrate wherein the liquid material penetrates substantially the substrate, e.g. by submerging the substrate into a bath containing the liquid material. - pulp: a dispersion e.g. an aqueous suspension comprising paper-making fibres and optional additives, which is to be processed, and covers the term "paper stock"; it also means dry paper-making fibres which are to be made into paper by either wet or dry processes. - sizing agent or hydrophobising agent: substances used during paper manufacture to reduce the paper's tendency when dry to absorb liquid, allowing inks and paints to remain on the surface of the paper and to dry there, rather than be absorbed into the paper or agent added in order to increase the hydrophobicity of the paper. - paper stock: term used to define pulp after mechanical (refining or beating) and/or chemical treatment (sizing, loading, dyeing, etc.) in the paper making process, e.g. the pulp ready to make paper.