Color Matching And Hue Analysis Of Iron Oxide Red Pigments

Iron oxide pigment is an important inorganic pigment,and its output is the second of the world's inorganic pigments,which is the largest amount of color pigments.Iron oxide red is a kind of the greatest demand of iron oxide pigments.Currently,controlling the quality of the hue and color uniform is the most closely monitored technical indicators and the difficulties for industrial enterprises.In this paper,the characterization of various mixed iron oxide red pigments prepared by a ‘mix acids method' is carried out.And the effect of oxidation reaction time on the hue of iron oxide red is studied.Microstructure and hue value of iron oxide red pigments are investigated using XRD,SEM,and Chroma Meter,respectively.L,a,b values of iron oxide red pigments at different reaction time are determined,and the relationship between a value and b value of iron oxide red is tested by a linear regression equation.Then,the color matching software of iron oxide pigment is compiled to forecast the types and proportion for mixing of iron oxide red according to the formula of color mixing equation and the least square method.Finally,the hue value(?L,?a,?b)of various iron oxide red is by statistics.And the correlation analysis is carried out using SPSS software.Hue evaluation program is constructed according to the actual production,which the program includes the hue pass rate,the hue values(?L,?a,?b)distribution percentage,and change trends of ?a value related to the saturation of pigments.The following conclusions can be drawn from the study.SEM test showes that the morphology of the synthesized iron oxide red pigment is spherical and the size distribution is ununiform.It can be obtained that iron oxide red is have a pure Fe2O3 phase through XRD analysis prepared by a different oxidation time.With the increase of reaction time,the particle size of iron oxide red increases,and the L value decreases first and then increases,while the a value and b value show a decreasing trend.Each type of pigment has a linear relationship of a value and b value,with the linear equation: b=1.60853a-30.18734,and the correlation coefficient of R2=0.8757.Linear regression curve represents average quality of hue value of synthesized iron oxide red pigment,above of line illustrates the red phase of pigment is insufficient,and below of line illustrates the red phase is higher than the average level.Through the analysis of red phase difference of [a] for iron oxide red pigment with the point within standard curve has the same b value,the quality classification of various pigments,especially equivalent yield of high red phase products(R70/R90/R150)and low red phase products(R40/R50/R80/R60/R140)can be calculated by the coefficient of ?a.The color matching software can be used to calculate the mixing of actual pigment powders,and to fast calculate the types and proportion of required iron oxide red according to the target color pigment,which can also be used for blending unknown color paste,can well meet the actual needs of industrial applications.And small batch of products are available through mixing by other types of iron oxide,which can be used for enterprises to optimize the layout of production varieties of iron oxide red.In addition,the color of the pigment product can be controlled accurately by the mixing of pigments,and the color consistency of the batch products can be maintained.Correlation analysis of hue value(?L,?a,?b)for various batches of iron oxide red products is carried out by SPSS software.The result shows that ?a and ?b is highly or moderately correlated,and ?L and ?b is not related,which is helpful to simplify the controlling parameter and improve the qualified rate of the hue for products.Through the construction of color evaluation scheme of iron oxide red pigment for monthly monitoring the change trend of the hue value,which can effectively manage the color quality of pigment for enterprise.The qualified rate of the hue and ?a(>0)ratio are two important indexes to evaluate the quality of color for pigment products,which can be considered to calculate the equivalent yield of workshop as a reference value,to promote the quality of products for workshop of pigments.