Estimating Hansen solubility parameters of organic pigments by group contribution methods

The Hansen solubility parameters(HSP)are frequently used for solvent selection and characterization of polymers,and are directly related to the suspension behavior of pigments in solvent mixtures.The performance of currently available group contribution(GC)methods for HSP were evaluated and found to be insufficient for computer-aided product design(CAPD)of paints and coatings.A revised and,for this purpose,improved GC method is presented for estimating HSP of organic compounds,intended for organic pigments.Due to the significant limitations of GC methods,an uncertainty analysis and parameter confidence intervals are provided in order to better quantify the estimation accuracy of the proposed approach.Compared to other applicable GC methods,the prediction error is reduced significantly with average absolute errors of 0.45 MPa^(1/2),1.35 MPa^(1/2),and 1.09 MPa^(1/2) for the partial dispersion(δD),polar(δP)and hydrogen-bonding(δH)solubility parameters respectively for a database of 1106 compounds.The performance for organic pigments is comparable to the overall method performance,with higher average errors forδD and lower average errors forδP andδH.

Preparation and properties of rare earth luminous fiber containing red organic fluorescent pigment

Rare earth luminous fiber was prepared by method of melt spinning. X-ray diffraction （XRD）, scanning electron micros-copy （SEM）, and fluorescence spectrophotometer as well as afterglow brightness tester were used to characterize the resulting sam-ples. Results from XRD and SEM demonstrated that the phase of SrA12O4：Eu2＋,Dy3＋in the fiber was not destroyed in the manufac-turing process and the as-formed luminous fiber consisted of irregular particles. Under ultraviolet excitation, the luminous fiber exhib-ited a yellow-green and orange-red emission band with a maximum at 520 nm and around 600 nm originating from SrAl2O4：Eu2＋, Dy3＋and red organic fluorescent pigments. The energy transfer process was further studied. Furthermore, the emission colors of lu-minous fibers could be tuned from yellow-green to orange-red easily by doping red organic fluorescent pigment, making the materials have potential application in many areas.

A core-shell composite pigment with rutile TiO_(2) intensification for UV inhibition

Organic pigments generlly have bright colors but poor ultraviolet(UV)resistance.To improve the UV for UVinhibition is proposed by afacile sol-gel method inthis work.Acore-shellstructure,witha homo resistance and extend the applications,a core-shell composite pigment with rutile Tio intensification geneous sol-gel TiO_(2) shell containing additional nanosized rutile TiO2 particles and with the pigment as the core,was established taking advantage of UV resistance of TiO2 and binding ability of sol-gel.While the sol-gel TiO2 shell alone has already shown obvious ultraviolet shielding effect,as tested over different sol-gel aging times and Tio2 loadings,the UV resistance of the fluorescent pigments was further enhanced by binding the nanosized rutile TiO2 in the sol-gel shell At a sol-gel TiO2 to rutile TiO2 ratio of 2:1,the UV exposure time is extended about eight times compared with that of the original pigment and twice as that of the modifed pigment with pure sol-gel TiO2 for the same color change.Therefore,the novel core-shell composite pigment intensified with nanosized rutile Tio2 particles is proved to be effcient in improving the uV resistance of organic pigments.