PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
the shortness of Ti resource and its relatively high value, low-cost synthesis techniques for TiO 2 pigment have been investigated. Moreover, phase control in TiO 2 synthesis is an interest for many research groups. Here we report on the preparation of titanium dioxide nanopigments with various morphologies by two methods namely; hydrothermal and hydrolysis at room temperature. A comparison between the characteristics of the produced titanium dioxide nanopigments from both routes is explored. Moreover, the use of the produced titanium dioxide nanostructures as a pigment in paper coating is also investigated. Experimental Materials The materials used in the present study to prepare nano titanium dioxide particles were, Titanium (IV) isopropoxide (C 12 H 28 O 4 Ti, TTIP, 97%, Aldrich), Tetrabutyl-orthotitanate (C 16 H 36 O 4 Ti, 97%, Fluka), as titanium precursor. Hydrochloric acid (HCl, assay 30%, Sic) was used as a hydrolysing agent. Ethyl alcohol (C 2 H 5 OH, 95%, Adwic) was used as washing, drying and non-aqueous media agent. Urea (NH 2 .CO.NH 2 , 99%, Adwic) was also used as a structure directing agent. All reagents were of chemical grade and were used as received without any further treatment. Acrylic copolymer latex (Acronal S801, BASF), clay pigment (EMAK company) and sodium hexametaphosphate dispersant (99%, Fine chemical company) were used for preparation of coating mixture. Preparation of titanium dioxide nanopigments Titanium dioxide nanopowders were prepared using two methods namely: (i) hydrothermal method and (ii) hydrolysis method at room temperature. In the case of hydrothermal method, a clear solution was obtained through addition of 0.2 molar of titanium isopropoxide dropwise into a mixture of 0.79 molar ethanol and 0.58 molar concentrated hydrochloric acid under magnetic stirring. Then the above mixture was diluted by adding distilled water. After stirring for half an hour, the mixture was transferred into Teflon-lined stainless steel autoclave. The autoclave was sealed and subjected to heat treatment at a temperature ranges from 100 to 140°C for 24 h. In the case of hydrolysis method at room temperature, the typical experimental procedure was as follows: 0.02 molar of tetrabutyl orthotitanate [Ti(OC 4 H 9 ) 4 ] was dissolved in 1.59 molar ethanol. After stirring for half an hour, the resulting solution was added dropwise into a 100ml of 0.25 molar urea in an ice bathed diluted hydrochloric acid aqueous solution under vigorous stirring to form a misty mixture. After further stirring for 4h, the mixture was allowed to stand at room temperature for almost 2 weeks. The obtained products from the two methods were washed several times with distilled water and then were centrifuged and kept in the suspension status for further paper coating applications. Application of the prepared nano TiO 2 pigment in paper coating Preparation of coatings The basic coating formula used in this study consisted of 100pph clay pigment, 15 pph binder and 0.3 parts of dispersant (pph = part per 100 parts of dry pigment). This sample
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Article 3 – Titanium Coating Pigments
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