Aqueous pigment dispersions having monomers in the polymeric dispersant capable of interacting with cellulose are described. These monomers include the ones having a structure of Formula (I): ##STR00001## wherein W is O or NH; R.sup.1 is C.sub.1-C.sub.8 alkyl; and R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are independently H or C.sub.1-C.sub.5 alkyl.

The present invention relates to an ink-jet printing method that is capable of obtaining good printed characters or images which are free of occurrence of white lines or streaks irrespective of irradiation with an active energy ray. The present invention provides an ink-jet printing method including the steps of ejecting at least one ink A selected from the group consisting of a black ink and chromatic inks onto a low-liquid absorbing printing medium and then ejecting a white ink thereonto, in which the ink A contains at least one pigment selected from the group consisting of a black pigment and chromatic pigments, and a polymer dispersant containing a constitutional unit derived from a polyalkylene glycol (meth)acrylate; and the white ink contains titanium oxide and a polymer dispersant containing a constitutional unit derived from a polyalkylene glycol (meth)acrylate.

The present invention relates to an ink-jet printing method that is capable of obtaining good printed characters or images which are free of occurrence of white lines or streaks irrespective of irradiation with an active energy ray. The present invention provides an ink-jet printing method including the steps of ejecting at least one ink A selected from the group consisting of a black ink and chromatic inks onto a low-liquid absorbing printing medium and then ejecting a white ink thereonto, in which the ink A contains at least one pigment selected from the group consisting of a black pigment and chromatic pigments, and a polymer dispersant containing a constitutional unit derived from a polyalkylene glycol (meth)acrylate; and the white ink contains titanium oxide and a polymer dispersant containing a constitutional unit derived from a polyalkylene glycol (meth)acrylate.

A printing ink formulation includes a functional material and a solvent being evaporable from the printing ink formulation to form a functional material thin film. The solvent is formed by mixing at least two organic solvents including a first solvent and a second solvent. The solvent system containing at least two solvents can effectively dissolve the functional material without the need of adding an additive, and can also effectively prevent the occurrence of a “coffee-ring effect”, and accordingly, the thin film containing a uniform thickness and a strong electron transmission capability can be obtained.

A printing ink formulation includes a functional material and a solvent being evaporable from the printing ink formulation to form a functional material thin film. The solvent is formed by mixing at least two organic solvents including a first solvent and a second solvent. The solvent system containing at least two solvents can effectively dissolve the functional material without the need of adding an additive, and can also effectively prevent the occurrence of a “coffee-ring effect”, and accordingly, the thin film containing a uniform thickness and a strong electron transmission capability can be obtained.

To provide a film-forming ink and a film formation method, capable of making the dimensional accuracy of a film to be formed excellent by increasing the apparent liquid droplet amount of a film-forming ink to be supplied as a liquid droplet into an opening part included in a partition wall, and also to provide a device with a film and an electronic apparatus, each of which has a film formed using the film formation method. A film-forming ink of the invention includes a film-forming material and a liquid medium in which the film-forming material is dissolved or dispersed, wherein the liquid medium contains a first component which has a boiling point at an atmospheric pressure of 200° C. or higher and a second component which has a boiling point at an atmospheric pressure lower than the first component.

To provide a film-forming ink and a film formation method, capable of making the dimensional accuracy of a film to be formed excellent by increasing the apparent liquid droplet amount of a film-forming ink to be supplied as a liquid droplet into an opening part included in a partition wall, and also to provide a device with a film and an electronic apparatus, each of which has a film formed using the film formation method. A film-forming ink of the invention includes a film-forming material and a liquid medium in which the film-forming material is dissolved or dispersed, wherein the liquid medium contains a first component which has a boiling point at an atmospheric pressure of 200° C. or higher and a second component which has a boiling point at an atmospheric pressure lower than the first component.

Provided is an ink containing water, a coloring material, and a copolymer, wherein the copolymer contains a structural unit represented by any one of general formulae (1a), (1b), and (1c) below and a structural unit containing an anionic group,

##STR00001##

where R.sub.1 represents a hydrogen atom or a methyl group, a represents an integer of from 6 through 10, and b represents an integer of 0 or 1,

##STR00002##

where R.sub.2 represents a hydrogen atom or a methyl group, c represents an integer of 3 or 4, and d represents an integer of 0 or 1,

##STR00003##

where R.sub.3 represents a hydrogen atom or a methyl group and e represents an integer of from 2 through 10.

Provided is an ink containing water, a coloring material, and a copolymer, wherein the copolymer contains a structural unit represented by any one of general formulae (1a), (1b), and (1c) below and a structural unit containing an anionic group,

##STR00001##

where R.sub.1 represents a hydrogen atom or a methyl group, a represents an integer of from 6 through 10, and b represents an integer of 0 or 1,

##STR00002##

where R.sub.2 represents a hydrogen atom or a methyl group, c represents an integer of 3 or 4, and d represents an integer of 0 or 1,

##STR00003##

where R.sub.3 represents a hydrogen atom or a methyl group and e represents an integer of from 2 through 10.

The present invention relates to an organic light emitting diode using a p-type oxide semiconductor containing gallium, and a preparation method therefor. According to the present invention, provided is an organic light emitting diode comprising an anode, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer and a cathode, wherein the hole injection layer is a p-type oxide semiconductor containing Ga.