Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05F—STATIC ELECTRICITY; NATURALLY-OCCURRING ELECTRICITY
  • H05F3/00—Carrying-off electrostatic charges

Definitions

• the invention relates to a table or workbench covering, which consists of a first electrically conductive layer with a specific resistance in the range from 5 x 10 6 ⁇ cm to 5 x 10 9 ⁇ cm and a second electrically conductive layer with a specific resistance in the range of 5 x 10 4 ⁇ cm to 5 x 10 7 ⁇ cm, which are each made of rubber compounds and which contain antistatic and / or electrically conductive particles, and are connected by calendering and vulcanization.
• Table coverings used in the electronics industry have two main functions. On the one hand, due to their specific resistance, they are able to render electrostatic charges on workpieces harmless due to their electrical conductivity, and on the other hand, their surface should avoid mechanical damage to electronic parts that are processed on them.
• Two-layer table coverings with a typical leakage resistance R G of 10 4 ⁇ 10 7 ⁇ are known from the Warmbier brochure. With the increasing demands on the storage density of hard disks, more and more demands are made regarding contamination-free production. In particular, this affects ionic contamination, which can cause corrosion on the hard drives in connection with moisture. Distracting have proven among other sulfate ions. Previous rubber table coverings show sulfate values which, determined by extraction with deionized water and ion chromatography, are in the order of 200-800 ⁇ g / cm 2 surface.
• the invention has for its object to provide a table or workbench covering of the type mentioned, the volume resistance measured according to the standard IEC 61340-4-1 about 10 7 ⁇ and the surface resistance is about 5 x 10 7 ⁇ and its extractable Sulfate content is reduced to an uncritical range.
• the object is achieved by a table or workbench covering, consisting of a first electrically conductive layer with a specific resistance in the range from 5 ⁇ 10 6 ⁇ cm to 5 x 10 9 ⁇ cm and a second electrically conductive layer with a specific resistance in the range of 5 x 10 4 ⁇ cm to 5 x 10 7 ⁇ cm, whereby the layers each consist of a rubber mixture, which contain antistatic and / or electrically conductive particles and are calendered together and connected by vulcanization and which have a sulfate content ⁇ 100 ⁇ g / cm extractable with deionized water 2 have.
• Such table or workbench coverings allow the production of computer hard disks with a very high storage density, since the corrosion effect of extractable sulfate ions depends on the amount of extractable sulfate ions and this is reduced by at least 50% compared to the known table or workbench coverings.
• the first layer is preferably the table or workbench coverings according to the invention light-colored and contains 5 -12% by weight of antistatic agents to produce the electrical conductivity.
• Glycol esters for example, are used as antistatic agents and / or quaternary ammonium compounds used.
• the second layer preferably contains the table or Workbench coverings 5 - 10% by weight of electrically conductive particles and / or fibers to generate electrical conductivity.
• the table or workbench coverings according to the invention consist of rubber mixtures, selected from the classes styrene-butadiene rubber (SBR) and / or acrylonitrile butadiene rubber (NBR) and contain 0 to 50% by weight mineral fillers, 0 to 10% by weight pigments and 0.2 to 10% by weight a peroxide crosslinking agent.
• SBR styrene-butadiene rubber
• NBR acrylonitrile butadiene rubber
• Processing aids are preferably used to facilitate processing such as stearic acid or zinc stearate added.
• Table or workbench coverings whose layers 2 to are particularly preferred Contain 7 wt .-% organic peroxides as crosslinking agents.
• Continuous layers are advantageously produced and these are produced continuously calendered and vulcanized together.
• the table or workbench coverings according to the invention are advantageously in the field of manufacturing electronic devices, especially in the Used in the field of computer hard drive manufacturing.
• the table or workbench covering according to the invention consists of a light-colored first layer which has limited electrical conductivity and a black, second layer which has good electrical conductivity and which are integrally connected to one another.
• the first layer consists of a rubber mixture based on polymers of the acrylonitrile-butadiene rubber (NBR) class, into which mineral fillers of the silicate class, antistatic agents for generating electrical conductivity, pigments for coloring and organic peroxides as crosslinking agents are mixed.
• the second layer consists of the same polymers and the same additives as the first layer with the difference that carbon black is added as an electrically conductive filler instead of the pigments.
• Both mixtures are mixed in each case in an internal mixer and the raw mixtures obtained are calendered to a final thickness of approx. 1.2 mm each.
• the webs of the first and second layers are laid one on top of the other and vulcanized in a continuous vulcanization machine at 100 to 190 ° C. under a specific pressure of 5 to 30 bar and joined together in one piece.
• Analysis of the sulfate ion concentrations extractable from finely chopped material with the aid of deionized water showed 65 ⁇ g / cm 2 of the table or workbench covering according to the invention.
• the composition of the individual layers is given in Table 1 below.

Landscapes

• Laminated Bodies (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Elimination Of Static Electricity (AREA)
• Paints Or Removers (AREA)

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Publications (1)

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ID=7706168

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Citations (2)

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• 2001
  • 2001-11-17 DE DE10156635A patent/DE10156635B4/de not_active Expired - Fee Related
• 2002
  • 2002-06-28 EP EP02014403A patent/EP1313355A1/de not_active Withdrawn
  • 2002-07-11 TW TW091115431A patent/TW544399B/zh not_active IP Right Cessation
  • 2002-08-21 CN CNB021305005A patent/CN1199785C/zh not_active Expired - Fee Related
  • 2002-09-02 ZA ZA200207032A patent/ZA200207032B/xx unknown
  • 2002-10-15 US US10/272,043 patent/US6959652B2/en not_active Expired - Fee Related
  • 2002-10-30 SK SK1546-2002A patent/SK15462002A3/sk unknown
  • 2002-10-31 BR BR0206281-0A patent/BR0206281A/pt not_active IP Right Cessation
  • 2002-11-05 CZ CZ20023654A patent/CZ20023654A3/cs unknown
  • 2002-11-12 MX MXPA02011129A patent/MXPA02011129A/es unknown
  • 2002-11-14 PL PL02357122A patent/PL357122A1/xx unknown
  • 2002-11-15 KR KR10-2002-0071016A patent/KR100486822B1/ko not_active IP Right Cessation
  • 2002-11-15 CA CA002411902A patent/CA2411902C/en not_active Expired - Fee Related
  • 2002-11-18 JP JP2002333304A patent/JP2003178898A/ja active Pending

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