Skip to content
Search Classifications
Search for IPC and CPC classification codes or keywords
IPC Subclass
D21G

CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES

Introduced: September 1968

Classification Context

Section:
TEXTILES; PAPER
Class:
PAPER-MAKING; PRODUCTION OF CELLULOSE
Subclass:
CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES

Description

D21G encompasses calendering equipment used in paper manufacturing to compress, smooth, and finish paper sheets, along with auxiliary devices integrated into papermaking lines. This includes calender rolls, nip structures, heating systems, and control mechanisms for regulating pressure, temperature, and sheet feed to achieve desired paper properties such as thickness uniformity, gloss, and density. The classification covers both standalone calendering units and machine components designed specifically to support the calendering process within integrated paper production systems.

5 direct subcodes

Child Classifications

Navigate with arrow keys, Enter to open

Top Applicants

Top 10 applicants by patent filingsfor class D21, 2013–2023, worldwide · Source: EPO PATSTAT

  1. VOITH PATENT DE 1,809
  2. STORA ENSO FI 1,467
  3. KEMIRA FI 1,086
  4. KIMBERLY-CLARK CORPORATION US 935
  5. VALMET TECHNOLOGIES FI 924
  6. VALMET SE 904
  7. P&G (PROCTER & GAMBLE COMPANY) US 862
  8. OJI HOLDINGS CORPORATION 696
  9. OMYA INTERNATIONAL CH 584
  10. SOUTH CHINA UNIVERSITY OF TECHNOLOGY 571