D21H PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
Description
D21H covers pulp compositions and their formulation methods that fall outside the scope of more specific pulp-focused subclasses (D21C–D21G), including additives, fillers, and processing modifications to cellulose fibers. It also encompasses surface treatments, impregnation, and coating techniques applied to finished paper that are not addressed in other classes or subclasses, as well as specialized paper types and post-production treatments not elsewhere classified. This subclass serves as a catch-all for paper and pulp innovations that do not fit neatly into dedicated mechanical, chemical, or conversion-specific categories. Examples include paper sizing, wet-strength additives, specialized coatings, and novel pulp blends.
Filing statistics
CPC subclass D21H recorded 50,846 patent applications worldwide between 2013 and 2023. Annual filings declined from 3,964 in 2013 to 3,670 in 2023 (-7%), peaking at 5,497 applications in 2018. The most active applicants in class D21 are VOITH PATENT (1,857 applications), STORA ENSO (1,552 applications) and KEMIRA (1,173 applications).
Source: EPO PATSTAT, worldwide filings
12 direct subcodes
Child Classifications
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- D21H 11/00 Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
- D21H 13/00 Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material (chemical features in the manufacture of artificial fibres D01F)
- D21H 15/00 Pulp or paper, comprising fibres or web-forming material characterised by features other than their chemical constitution
- D21H 17/00 Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H 19/00 Coated paper (coated fibreboard D21J1/08); Coating material (recording sheets characterised by the coating used to improve ink, dye or pigment receptivity B41M5/50)
- D21H 21/00 Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
- D21H 23/00 Processes or apparatus for adding material to the pulp or to the paper (applying liquids or other fluent material to surfaces, in general B05; processes for making continuous lengths of paper D21F11/00)
- D21H 25/00 After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
- D21H 27/00 Special paper not otherwise provided for, e.g. made by multi-step processes
Top Applicants
Top 10 applicants by patent filingsfor class D21, 2013–2023, worldwide · Source: EPO PATSTAT
- VOITH PATENT DE 1,857
- STORA ENSO FI 1,552
- KEMIRA FI 1,173
- KIMBERLY-CLARK CORPORATION US 1,107
- VALMET TECHNOLOGIES FI 965
- VALMET SE 943
- P&G (PROCTER & GAMBLE COMPANY) US 941
- OMYA INTERNATIONAL CH 821
- UPM-KYMMENE CORPORATION FI 512
- SEIKO EPSON CORPORATION JP 501