BS EN 12877-3:2000 – Colouring materials in plastics一 Determination of colour stability to heat during processing of colouring materials in plastics – Part 3: Determination by oven test
4 Materials
4.1 Test medlum,旧be agreed between the interested prtes.
When evaluating pigments in polyinyl chloide, the test medium shall be adequately sabilzed to heat,. The therelr
colour stability of the test medium when subjected to heat shall therefore be tested with and without 6 doxide pigment, using the same procedure. f thare are changes, these shall be taken into account when expressing 1est resultst
4.2 Titanium dioxide pigment, grade as recomm nded for use in plastcs.
5 Apparatus
5.1 Air eirculating oven, cepoble of maintaining temperetures up to 260心preferbly to wihin+1 C, but .
not exeding +3 C.
The oven shall be capable of regaining the test temperatures within 30 s ater the specimen has been plaoed in i. It shall be fited with focd-ventitio equipment Shelves shall be such that they llow the free circulation of air within the owen. To regain the test temperature in the specifed time, the ar oven may be provided with a drawer in the door and/or a metal block for higher heat apacity.
5.2 Temperature-measuring device. for measuring the tempereture in the oven as ckse as possible t如o the specimens.
5.3 Aluminlum sheets, uncoated and degreased, of thickness 0,2 mm to 0.4 mm, The sheets shall be a few cenfimelers sma ler than the sheves or drawers of the oven. The front edge of the sheets nay be bent upwards to fcitatle hand ing
5.4 Plate press, provded wh a heating and coolng system.
5.5 Spectrophotometer or tritimulus colorimeter, for colour measurements in acordance with 1IS0 77242.
6 Sampling
See EN 12877-1.
7 Test specimens
7.1 Form and dmiensions
Unless otherwtse specthed or agreed, test specimens of dmensions 50 mmx 50mm x 1 mm, sullable for colorimeltry, shall be used.
7.2 Concentration of colouring material
The colouring mrial shall be tested in reduced shade (72.1) and/or in ull shade 722).
7.2.1 For testing in reduced shade, the concentration of the colouring malerial in the test medium shall correspond toc
a) 1/3 standard depth of shade (SD) in BcCordance with EN 177-1999. annex A or
b) 125 standard dapth ol shade (SD) in accordance with EN 126771:1999 annex A or
q) an agreed redution ratio.
For a lest specimen ticoness of 1 mm 5 % of taniuim dioxide pigment is nessry to obtein full hiding.
7.2.2 For testing in full shade, the concentration of the coloring materal in the lest medum shall crrespond to 7.2.1孙Altemathely, a concentration of 0.1 % (pefernd for organic pigments and dhestufs), or 2 % (referred for inorganic pigments) or another agreed appropriate concenration shall be taken.
BS EN 12877-3:2000 – Colouring materials in plastics一 Determination of colour stability to heat during processing of colouring materials in plastics – Part 3: Determination by oven test