Image forming material

1. An image forming material comprising:

a perimidine-substituted squarylium dye that has a structure represented by the following formula (I) and shows diffraction peaks at least at Bragg angles (2θ±0.2°) of 17.7°, 19.9°, 22.1°, 23.2° and 24.9° in its X-ray powder diffraction spectrum measured by irradiation with X rays generated from a Cu target with a wavelength of 1.5405 angstroms:

2. The image forming material as described in claim 1 , wherein

the perimidine-substituted squarylium dye is obtained by mixing a perimidine-substituted squarylium dye having the structure represented by the formula (I) and a solution of sodium dodecylbenzenesulfonate and then subjecting the mixed solution to a treatment for conversion into pigment.

3. The image forming material as described in claim 1 , wherein

the perimidine-substituted squarylium dye is in a state of a crystalline particle having a median diameter d50 of about 10 nm to about 300 nm.

4. The image forming material as described in claim 1 , wherein the perimidine-substituted squarylium dye is contained in an amount of about 0.05% by weight to about 3% by weight.

5. The image forming material as described in claim 1 , which is an electrophotographic toner; an inkjet printer ink; or an ink for letterpress printing, offset printing, flexographic printing, gravure printing or silk-screen printing.

6. The image forming material as described in claim 1 , which satisfies conditions represented by the following expressions (II) and (III):

0 ≦ΔE≦ 16  (II)

(100− R )≧75  (III)

wherein

in the expression (II), ΔE represents a color difference in the CIE1976 L*a*b* color specification system, which is given by the following expression (IV):

Δ E =√{square root over (( L 1 −L 2 )+( a 1 −a 2 ) 2 +( b 1 −b 2 ) 2 )}{square root over (( L 1 −L 2 )+( a 1 −a 2 ) 2 +( b 1 −b 2 ) 2 )}{square root over (( L 1 −L 2 )+( a 1 −a 2 ) 2 +( b 1 −b 2 ) 2 )}  (IV)

wherein

in the expression (IV), L 1 , a 1 and b 1 represent values of L, a and b, respectively, of a recording material surface, on which no image is formed yet, and

L 2 , a 2 and b 2 represent values of L, a and b, respectively, in a formed image part of the recording material surface, where a fixed image having an adhered amount is 4 g/m 2 is formed by use of the image forming material, and

in the formula (III), R (unit: %) represents a reflectance of infrared radiation with the wavelength of 850 nm on the formed image part.