There is provided a maintenance liquid, which is used in maintenance of a device equipped with a discharge head for discharging an ultraviolet ray curable-type composition containing the acyl phosphine oxide-based photopolymerization initiator toward an attachment object, including a polymerizable compound in which a saturation solubility of an acyl phosphine oxide-based photopolymerization initiator at 20° C. is equal to or greater than 5.0% by mass.

An actinic ray-sensitive or radiation-sensitive resin composition contains a resin (A) and a resin (B) which include a repeating unit having an acid-decomposable group, and the acid-decomposable group in the resin (A) and the acid-decomposable group in the resin (B) have the same structures. Regarding the resin (A) and the resin (B), |G.sub.A−G.sub.B| is from 5% by mole to 20% by mole, S.sub.A/S.sub.B is 10/90 to 90/10, |Mw.sub.A−Mw.sub.B| is from 100 to 5,000, and |Mw.sub.A/Mn.sub.A−Mw.sub.B/Mn.sub.B| is 0.05 or more.

An actinic ray-sensitive or radiation-sensitive resin composition contains a resin (A) and a resin (B) which include a repeating unit having an acid-decomposable group, and the acid-decomposable group in the resin (A) and the acid-decomposable group in the resin (B) have the same structures. Regarding the resin (A) and the resin (B), |G.sub.A−G.sub.B| is from 5% by mole to 20% by mole, S.sub.A/S.sub.B is 10/90 to 90/10, |Mw.sub.A−Mw.sub.B| is from 100 to 5,000, and |Mw.sub.A/Mn.sub.A−Mw.sub.B/Mn.sub.B| is 0.05 or more.

Provided are a photoacid generator, a photoresist composition including the same, and a method of forming a pattern by using the photoacid generator. The photoacid generator includes a copolymer of a monomer that generates an acid upon exposure to light and an acid-labile monomer of which solubility with respect to a developing solvent is changed by decomposition by an acid, wherein the copolymer is represented by Formula 1:

##STR00001## wherein, in Formula 1, x, y, L, A.sup.−, B.sup.+, R.sub.1, R.sub.2, and R.sub.3 are each the same as described in the detailed description.

A positive resist composition is provided comprising a base polymer end-capped with a salt consisting of an ammonium cation linked to a sulfide group and a fluorinated anion. Because of controlled acid diffusion, a resist film of the composition forms a pattern of good profile with a high resolution and reduced edge roughness or dimensional variation.

An inkjet ink contains a pigment, a specific polymer, a water-soluble organic solvent, and water. The specific polymer includes at least one first repeating unit, at least one second repeating unit, at least one third repeating unit, and at least one fourth repeating unit. The first repeating unit is a repeating unit derived from a monomer having a salt-forming group. The second repeating unit is a repeating unit derived from a styrene-based monomer. The third repeating unit is a repeating unit derived from a styrene-based macromer having a polymerizable functional group at one end thereof. The fourth repeating unit is a repeating unit derived from nonionic acrylic acid ester or nonionic methacrylic acid ester.

A self-crosslinked polymeric dispersant including a self-crosslinked polymeric dispersant comprising: a copolymer comprising: an acid group; a base group; a hydrophobic group; and a steric hydrophilic group.

Disclosed herein is a bio-based copolymer comprising in polymerized form (i) at least one polymerizable bio-based monomer containing one phenolic hydroxyl group which has been derivatized to provide at least one polymerizable functional group which is an ethylenically unsaturated functional group (such as a [meth]acrylate group), where the precursors of the polymerizable bio-based monomers are derived from raw lignin-containing biomass, and (ii) at least one ion-conducting co-monomer other than the bio-based monomer. Also disclosed herein are binders comprising the bio-based copolymer, electrodes comprising the binder, polymer electrolytes comprising the bio-based copolymer and an electrochemical device comprising an electrode in electrical contact with a polymer electrolyte, wherein at least one of the electrode and the polymer electrolyte comprises the bio-based copolymer.

Disclosed herein is a bio-based copolymer comprising in polymerized form (i) at least one polymerizable bio-based monomer containing one phenolic hydroxyl group which has been derivatized to provide at least one polymerizable functional group which is an ethylenically unsaturated functional group (such as a [meth]acrylate group), where the precursors of the polymerizable bio-based monomers are derived from raw lignin-containing biomass, and (ii) at least one ion-conducting co-monomer other than the bio-based monomer. Also disclosed herein are binders comprising the bio-based copolymer, electrodes comprising the binder, polymer electrolytes comprising the bio-based copolymer and an electrochemical device comprising an electrode in electrical contact with a polymer electrolyte, wherein at least one of the electrode and the polymer electrolyte comprises the bio-based copolymer.

Provided are a photosensitive composition including a coloring material A including a pigment, a pigment derivative B, and a dispersant C, in which the pigment derivative B includes a pigment derivative B1 in which a maximum value of a molar absorption coefficient in a wavelength range of 400 to 700 nm is 3000 L.Math.mol.sup.−1.Math.cm.sup.−1 or less, the dispersant C includes a dispersant C1 having an ethylenically unsaturated bond-containing group, and a total content of the coloring material A and the pigment derivative B in a total solid content of the photosensitive composition is 50% by mass or more; a film formed of the photosensitive composition; an optical filter, a solid-state imaging element; and an image display device.