The present disclosure relates to Quinacridone pigment and a process of preparation thereof. The Quinacridone pigment of the present disclosure exhibit higher chemical resistance to solvents, higher stability and higher resistance to acid and alkali.

A quinacridone solid solution pigment that allows a colored product to have high chroma and a properly yellowish hue and has a controlled particle diameter, and a method for producing the quinacridone solid solution pigment. In the method, a water-containing crude quinacridone solid solution is produced by a co-cyclization reaction of a diarylaminoterepththalic acid and a dialkylarylaminoterephthalic acid in polyphosphoric acid, then the resulting water-containing crude quinacridone solid solution having a mass ratio of unsubstituted quinacridone to a 2,9-dialkylquinacridone of 85:15 to 60:40 is dried, thereby obtaining a powdery, crude quinacridone solid solution having a water content of less than 1%. Then, the resulting powdery, crude quinacridone solid solution is heated in a liquid medium that does not dissolve the crude quinacridone solid solution. Also, a pigment dispersion liquid and an inkjet ink each containing the obtained quinacridone solid solution pigment are provided.

A quinacridone solid solution pigment that allows a colored product to have high chroma and a properly yellowish hue and has a controlled particle diameter, and a method for producing the quinacridone solid solution pigment. In the method, a water-containing crude quinacridone solid solution is produced by a co-cyclization reaction of a diarylaminoterepththalic acid and a dialkylarylaminoterephthalic acid in polyphosphoric acid, then the resulting water-containing crude quinacridone solid solution having a mass ratio of unsubstituted quinacridone to a 2,9-dialkylquinacridone of 85:15 to 60:40 is dried, thereby obtaining a powdery, crude quinacridone solid solution having a water content of less than 1%. Then, the resulting powdery, crude quinacridone solid solution is heated in a liquid medium that does not dissolve the crude quinacridone solid solution. Also, a pigment dispersion liquid and an inkjet ink each containing the obtained quinacridone solid solution pigment are provided.

A photosensitive coloring composition includes a magenta pigment having an average primary particle diameter of 50 nm or less, a polymerizable compound, a photopolymerization initiator, and an ultraviolet absorber, in which the magenta pigment has a maximum absorption wavelength in a range of 500 to 600 nm, and in a case where an absorbance of the maximum absorption wavelength is 1, a wavelength at which an absorbance is 0.5 is 450 nm or more on a side where a wavelength is shorter than the maximum absorption wavelength and is 650 nm or less on a side where a wavelength is longer than the maximum absorption wavelength.

A photosensitive coloring composition includes a magenta pigment having an average primary particle diameter of 50 nm or less, a polymerizable compound, a photopolymerization initiator, and an ultraviolet absorber, in which the magenta pigment has a maximum absorption wavelength in a range of 500 to 600 nm, and in a case where an absorbance of the maximum absorption wavelength is 1, a wavelength at which an absorbance is 0.5 is 450 nm or more on a side where a wavelength is shorter than the maximum absorption wavelength and is 650 nm or less on a side where a wavelength is longer than the maximum absorption wavelength.

The present disclosure relates to magenta inkjet inks having a quinacridone pigment and an azo pigment. The azo pigment has at least one azo compound having the formula (I), in which R.sub.a is selected from H, aryl and C.sub.1 to C.sub.4 alkyl, and R.sub.b, R.sub.c and R.sub.d are each independently selected from H, a C.sub.1 to C.sub.4 alkyl, an oxygen-containing, a nitrogen-containing and a sulphur-containing functional group. Where R.sub.a is aryl, the aryl is not a phenyl group having at least one hydrogen atom that has been substituted with a chlorine atom. ##STR00001##

The present disclosure relates to magenta inkjet inks having a quinacridone pigment and an azo pigment. The azo pigment has at least one azo compound having the formula (I), in which R.sub.a is selected from H, aryl and C.sub.1 to C.sub.4 alkyl, and R.sub.b, R.sub.c and R.sub.d are each independently selected from H, a C.sub.1 to C.sub.4 alkyl, an oxygen-containing, a nitrogen-containing and a sulphur-containing functional group. Where R.sub.a is aryl, the aryl is not a phenyl group having at least one hydrogen atom that has been substituted with a chlorine atom. ##STR00001##

Quinacridone pigments that are surface-functionalized with glycidyl methacrylate, maleic anhydride, or 4-methacryloxyethyl trimellitic anhydride to create a functionalized pigment. The functional groups are then activated to bond hydrophobic polymers, thereby coating the pigment with the hydrophobic polymers. The quinacridone pigments can be used for a variety of applications. They are well-suited for use in electro-optic materials, such as electrophoretic media for use in electrophoretic displays.

Quinacridone pigments that are surface-functionalized with glycidyl methacrylate, maleic anhydride, or 4-methacryloxyethyl trimellitic anhydride to create a functionalized pigment. The functional groups are then activated to bond hydrophobic polymers, thereby coating the pigment with the hydrophobic polymers. The quinacridone pigments can be used for a variety of applications. They are well-suited for use in electro-optic materials, such as electrophoretic media for use in electrophoretic displays.

A polysiloxane-substituted quinacridone pigment is produced by a quinacridone pigment with an epoxy-terminated polysiloxane under conditions effective to cause the epoxy group on the polysiloxane to react with, and bond the polysiloxane to, the quinacridone pigment. The quinacridone pigment thus produced has the polysiloxane grouping bonded to one of the quinacridone nitrogen atoms via a hydrocarbon linking group, which bears a hydroxyl group on a carbon atom or to the quinacridone nitrogen atom. These quinacridone pigments are useful in electrophoretic displays.