WO2002096650A1 - Frame preparation for screen printing - Google Patents
Frame preparation for screen printing Download PDFInfo
- Publication number
- WO2002096650A1 WO2002096650A1 PCT/GB2002/002165 GB0202165W WO02096650A1 WO 2002096650 A1 WO2002096650 A1 WO 2002096650A1 GB 0202165 W GB0202165 W GB 0202165W WO 02096650 A1 WO02096650 A1 WO 02096650A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- frame
- heating
- carried out
- frames
- screen printing
- Prior art date
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41F—PRINTING MACHINES OR PRESSES
- B41F35/00—Cleaning arrangements or devices
- B41F35/003—Cleaning arrangements or devices for screen printers or parts thereof
- B41F35/005—Cleaning arrangements or devices for screen printers or parts thereof for flat screens
Definitions
- This invention relates to frame preparation for screen printing and in particular to a process for regenerating used frames.
- Screen printing is a process in which ink is forced through open areas of a stencil onto a substrate using a squeegee.
- the stencil is supported on a taught mesh, usually of nylon or polyester, attached to a rigid frame, usually of aluminium or steel.
- the adhesive can also be removed from the frames by blasting the frames using a number of different media (e.g. sand blasting).
- blasting will also deteriorate the frames when it is done repeatedly and there will come a point when the frames will have to be replaced with new frames.
- both grinding and blasting create airborne particles. These airborne particles cannot be allowed to contaminate the finished product of the printing process and hence the grinding or blasting facility has to be maintained in an isolated, air-cleaned room and ideally at another site. When blasting, large storage bins are also required to hold the blasting media.
- the adhesive can also be removed from the frames by soaking the frames in a chemical solution.
- the chemicals used to remove the adhesives typically take 30 minutes or longer to loosen up the adhesives and even then the adhesive may have to be removed by scraping. These chemicals are often very hazardous and carcinogenic in nature. These chemicals can be very expensive and difficult to handle and must be disposed of according to stringent environmental regulations.
- the frames may require an additional process, i.e. grinding or blasting. This is especially true for frames which have had the adhesive removed by chemical means.
- the present invention provides a process for regenerating used screen printing frames contaminated with residues from the screen printing process comprising heating the used frame at a sufficient temperature and for sufficient time to thermally degrade the residues.
- the residue is one or more of a mesh, an adhesive, a printing ink, or residual paint.
- the heating is carried out at from 150°C to below the distortion point of the frame. More preferably the frame consists substantially of aluminium and heating is carried out at 150 to 425°C or the frame consists substantially of steel and heating is carried out at 150 to 650°C. More preferably the heating is carried out at 315 to 425°C. Most preferably the heating is carried out at 370°C.
- heating is carried out for 30 min to 8 hours, particularly preferably for 1 to 2 hours.
- the heating is carried out until the residues are degraded to a dry ash.
- the process further comprises the application of a powder coating to the frame, particularly preferably the powder coating is an epoxy or polyester based formulation.
- the present invention relates to a heat-cleaning process to remove mesh, adhesive, printing ink and/or residual paint from the frames.
- the frames are then powder coated to prevent them from rusting and to provide a consistent/uniform profile to which mesh can be attached.
- the mesh, adhesive and printing ink applicable to this invention are not critical to the success and are well known in the art. As long as these are primarily organic materials, if residue remains they can be converted to gaseous decomposition products. Any minority inorganic components remain as a dry ash which can easily be removed.
- the mesh may be any manufactured from polyester or nylon yarns and typically those manufactured by the companies Saati and Sefar Inc.
- the adhesive can be any of the proprietary adhesives normally used in the art. Examples include polyester urethane solvent based adhesives, e.g. Serifix manufactured by Sericol, or Cyanoacrylate solvent based adhesives or solvent-free UV curable adhesives. These materials degrade well below the melting point of the frame.
- the frames used in screen printing are steel or aluminium. Temperatures over 650°C (1200°F) are required to distort the steel frames and temperatures over 425°C (800°F) are required to distort aluminium frames. (Aluminium melts at 600 to 650°C (1100 to 1200°F))
- the heat-cleaning process of the present invention thermally degrades the mesh, adhesive, printing ink and any old paint on the frames reducing them to a non- hazardous dry ash.
- the operator should ensure that dry ash dust meets the relevant EPA and solid waste disposal standards (e.g. in the USA those governed by the RCRA/SARA).
- the upper temperature limit is determined by the stability of the frame material.
- the frame must not be heated above the point at which the frame distorts (the 'distortion point') thereby rendering the treated frame unsuitable for use in subsequent screen printing processes.
- the upper temperature limit at which the frame distorts will vary depending on the metal from which the frame is constructed. For example, an aluminium frame must not be heated above 425°C (800°F). A person skilled in the art would be able to adjust the temperature, and duration, of the heating process depending on the frame material.
- the duration of heating the frame to remove contaminants will vary depending on the temperature of the oven. This may be from 30 min at 650°C (1200°F) to 8 hours at 150°C (300°F). Typically, for a steel frame, heating would be for 2 hours or less at 370°C (700°F)
- the present process may be performed repeatedly (50 times or more) without deteriorating the frame.
- any toxic fumes created in the process are converted by an after burner into clean, environmentally safe, odourless gases.
- the hot stack gases discharged to the atmosphere consist primarily of excess oxygen, nitrogen, water vapour and carbon dioxide. This assures compliance with the most stringent World Environmental Standards such as in the US EPA and regional air pollution standards, and in Europe, regulations governed by the European Environmental Protection Acts.
- the frames are then preferably painted with a powder coat to prevent them from rusting and to provide the same consistent profile (via the powder coat) on all frames. By applying a powder coating, the mesh can be easily and consistently attached to every frame.
- Powder coatings are known in the art, for example epoxy resin, such as Sherwin Williams Powdura Card i.e. Iron Gate #EBS2-C000 or Herberts O'Brien product Pac Black #EFB- 408-S3 or polyester resin, such as Sherwin Williams Low Cure Black Polyester TGIG #01T-0152 PBS2, but may be any number of the commercially available powder coatings which give good adhesion to frame and glue to powder coat, and chemical resistance to the chemicals used in the screen printing process.
- epoxy resin such as Sherwin Williams Powdura Card i.e. Iron Gate #EBS2-C000 or Herberts O'Brien product Pac Black #EFB- 408-S3
- polyester resin such as Sherwin Williams Low Cure Black Polyester TGIG #01T-0152 PBS2
- Example 1 Steps in the present process for heat-cleaning carbon steel frames are:
- Steps in the present process for heat-cleaning aluminium frames are:
- Example 2 The same process was carried out as for Example 1 except with aluminium frames the temperature of the bake-off oven is ramped up to 315°C (600°F) in 30 minutes and then held at 315°C (600°F) for approximately 90 minutes.
- Polyester coating "Sherwin Williams Low Cure Black Polyester TGIG #01T-0152/PBS2" is used as the powder coating.
- the surface temperature of the powder coated frame is heated to 205°C (400°F) for approximately 10 minutes.
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/478,712 US20040163553A1 (en) | 2001-10-19 | 2002-05-10 | Frame preparation for screen printing |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US29441401P | 2001-05-29 | 2001-05-29 | |
US60/294,414 | 2001-05-29 | ||
GB0125193A GB0125193D0 (en) | 2001-05-29 | 2001-10-19 | Frame preparation for screen printing |
GB0125193.3 | 2001-10-19 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2002096650A1 true WO2002096650A1 (en) | 2002-12-05 |
Family
ID=26246679
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB2002/002165 WO2002096650A1 (en) | 2001-05-29 | 2002-05-10 | Frame preparation for screen printing |
Country Status (1)
Country | Link |
---|---|
WO (1) | WO2002096650A1 (en) |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3916374A (en) * | 1973-09-27 | 1975-10-28 | Siemens Ag | Traffic signaling system |
-
2002
- 2002-05-10 WO PCT/GB2002/002165 patent/WO2002096650A1/en not_active Application Discontinuation
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3916374A (en) * | 1973-09-27 | 1975-10-28 | Siemens Ag | Traffic signaling system |
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