Provided is a 4-oxoquinoline compounds of the formula (I) (I) wherein A is selected from diradicals of the formulae (A.1), (A.2), (A.3), (A.4), (A.5) and (A.6), (A.1) (A.2) (A.3) (A.4) (A.5) (A.6) wherein R.sup.1, R.sup.2a, R.sup.2b, R.sup.3, R.sup.3a, if present R.sup.4a, R.sup.4b, R.sup.5a, R.sup.5b, R.sup.6a, R.sup.6b, R.sup.6c, R.sup.6d, R.sup.n1, R.sup.n2, R.sup.n3, R.sup.n4, R.sup.m5, R.sup.m6, R.sup.m7, R.sup.m8, R.sup.7, R.sup.8a, R.sup.9 and R.sup.9a are as defined in the claims and in the description. Also provided is a method for their preparation and their use.

##STR00001## ##STR00002##

A 4-hydroxquinoline compound has the formula (I)

##STR00001## wherein A is selected from diradicals of the formulae (A.1), (A.2), (A.3), (A.4), (A.5), and (A.6) wherein R.sup.1, R.sup.2a, R.sup.2b, R.sup.3, if present R.sup.4a, R.sup.4b, R.sup.5a, R.sup.5b, R.sup.6a, R.sup.6b, R.sup.6c, R.sup.6d, R.sup.n1, R.sup.n2, R.sup.n3, R.sup.n4, R.sup.m5, R.sup.m6, R.sup.m7, R.sup.m8, R.sup.7, R.sup.8a, R.sup.9 are as defined in the description.

Disclosed is a photochromic composition comprising a naphthopyran-based photochromic compound having a specific structure and an oligomer.

Disclosed is a photochromic composition comprising a naphthopyran-based photochromic compound having a specific structure and an oligomer.

The present disclosure provides an encapsulated pigment dispersion and an inkjet ink comprising an ink vehicle and an encapsulated pigment dispersion thereof. In particular, the encapsulated pigment dispersion includes a pigment selected from TiO.sub.2 pigment, fluorescent pigment, phosphorescent pigment, and mixtures thereof. The present disclosure also provides a process for producing the aqueous pigment.

The present disclosure provides an encapsulated pigment dispersion and an inkjet ink comprising an ink vehicle and an encapsulated pigment dispersion thereof. In particular, the encapsulated pigment dispersion includes a pigment selected from TiO.sub.2 pigment, fluorescent pigment, phosphorescent pigment, and mixtures thereof. The present disclosure also provides a process for producing the aqueous pigment.

A preparation method of pearlescent pigment coating materials is provided. The method of the present invention lies in that titanium-iron ions in ilmenites are dissolved by using a hydrochloric acid at a certain temperature and pressure, and then ferrous chloride in the acidolysis solution is precipitated by adding hydrogen chloride gas, the remaining titanium-iron ions are separated from other colored ions by means of co-extraction using an extractant upon oxidation, and an enriched titanium oxydichloride solution and ferrous hydrous oxide are obtained by employing a fractional back extraction and enrichment method, the titanium oxydichloride solution can be used for mica-titanium based pearlescent pigment coating materials, and can also be used for preparing titanium dioxide; and the acidified ferrous hydrous oxide and the oxidized ferrous chloride can be used as iron based pearlescent pigment coating materials or used for preparing iron oxide pigments.

A preparation method of pearlescent pigment coating materials is provided. The method of the present invention lies in that titanium-iron ions in ilmenites are dissolved by using a hydrochloric acid at a certain temperature and pressure, and then ferrous chloride in the acidolysis solution is precipitated by adding hydrogen chloride gas, the remaining titanium-iron ions are separated from other colored ions by means of co-extraction using an extractant upon oxidation, and an enriched titanium oxydichloride solution and ferrous hydrous oxide are obtained by employing a fractional back extraction and enrichment method, the titanium oxydichloride solution can be used for mica-titanium based pearlescent pigment coating materials, and can also be used for preparing titanium dioxide; and the acidified ferrous hydrous oxide and the oxidized ferrous chloride can be used as iron based pearlescent pigment coating materials or used for preparing iron oxide pigments.

Provided are thermochromic color-memorizing composition and thermochromic color-memorizing microcapsule pigment encapsulating the same, the thermochromic color-memorizing composition including: (a) an electron-donating color-developing organic compound; (b) an electron-accepting compound; and (c) an ester compound represented by the following formula (1) as a reaction medium which controls color reaction between the components (a) and (b):

##STR00001##

Provided are thermochromic color-memorizing composition and thermochromic color-memorizing microcapsule pigment encapsulating the same, the thermochromic color-memorizing composition including: (a) an electron-donating color-developing organic compound; (b) an electron-accepting compound; and (c) an ester compound represented by the following formula (1) as a reaction medium which controls color reaction between the components (a) and (b):

##STR00001##