TECHNICAL FIELD

The present invention relates to glitter pigments, and particularly relates to a glitter pigment including a flaky substrate, optical interference film formed on the surface of the flaky substrate, and fine particles attached to the optical interference film. The present invention also relates to a composition containing a glitter pigment and to a painted product having a paint film containing a glitter pigment.

BACKGROUND ART

Glitter pigments are added to various products such as paints, cosmetics, and so on to allow the products to reflect light with sparkles. A typical property required of glitter pigments is high brightness. Glitter pigments each including a flaky substrate are suitable for achieving this desirable property. Glitter pigments each including an optical interference film present pearly gloss due to an optical interference effect. A typical optical interference film is a titanium oxide film. Glitter pigments allowed to present a desired color by attachment of fine metal particles are also known. Typical fine metal particles are fine gold particles presenting color by surface plasmon resonance.

It has been proposed to improve the vividness of reflected light by making interference color presented by an optical interference film and color presented by fine metal particles similar to each other. Patent Literature 1 discloses a red or yellow glitter pigment with improved vividness. Examples 1 to 4 of Patent Literature 1 disclose glitter pigments each including: a flaky substrate having a surface on which a titanium oxide film with a thickness at which interference color is red is formed; and red fine gold particles attached to the titanium oxide film. Example 5 of Patent Literature 1 discloses a glitter pigment including: a flaky substrate having a surface on which a titanium oxide film with a thickness at which interference color is yellow is formed; and yellow fine silver particles attached to the titanium oxide film.

Patent Literature 2 discloses a technique for enhancing the vividness of a blue or green reflected color by using fine gold particles which have been used as a red-color former. The glitter pigment of Patent Literature 2 includes: a titanium oxide film formed on the surface of a flaky substrate to have a thickness at which interference color is blue or green; and fine gold particles attached to the titanium oxide film and then heated to change the aggregation state. The heating changes the aggregation state of the fine gold particles, which thus become a color former that improves the vividness of a blue or green reflected light.

CITATION LIST

Patent Literature

Patent Literature 1: JP 2006-299051 A

Patent Literature 2: WO 2016/194352 A1

SUMMARY OF INVENTION

Technical Problem

Reflected color presented by glitter pigments and resulting from optical interference varies depending on the angle at which the glitter pigments are observed. For example, an optical interference film can be designed to be able to present a reflected color close to a human skin color in a direction of regular reflection of incident light. However, when a film including a glitter pigment including this optical interference film is observed from a different direction, a slightly greenish reflected color can sometimes be observed. Such a shift of color (which may hereinafter be referred to as “color shift”) is desirably reduced because such a shift of color can be a cause of an unnatural impression in some applications typified by cosmetics.

In the case of glitter pigments in which fine metal particles are attached to an optical interference film, an observation angle-dependent color shift of reflected light is reduced thanks to colors of the fine metal particles. However, as disclosed in Patent Literatures 1 and 2, glitter pigments each including an optical interference film and fine metal particles have conventionally been designed with the aim of enhancing the vividness of reflected light in a regular reflection direction. Because of this, the brightness of reflected light from these glitter pigments greatly varies depending on the angle of observation. In this respect, the unnatural impression has not yet been removed sufficiently.

Therefore, the present invention aims to provide a glitter pigment suitable for imparting high brightness to reflected light toward a regular reflection direction and reducing the unnaturalness caused by an observation angle-dependent variation in reflected light.

Solution to Problem

The present invention provides a glitter pigment including:

a flaky substrate;

an optical interference film formed on a surface of the flaky substrate; and

fine light scattering particles attached to the optical interference film, wherein

reflected light, as measured using illuminant D65, is represented by an L* (15) value of more than 100, a ΔL*(h−s) value of less than 30, and a Δh(h−s) value of less than 40° in an L*C*h color system, wherein

the L*(15) value is an L* value of the reflected light toward a 15° direction based on an angular representation in which, when the illuminant is disposed so that an incident angle of incident light from the illuminant is 45°, an angle at which the incident light is regularly reflected is defined as 0° and an incident direction of the incident light is defined as 90°,

the ΔL*(h−s) value is a difference obtained by subtracting an average value L*(s) of an L*(75) value of the reflected light toward a 75° direction and an L* (110) value of the reflected light toward a 110° direction from an average value L* (h) of the L*(15) value of the reflected light toward the 15° direction and an L*(25) value of the reflected light toward a 25° direction when the directions are based on the angular representation, and

the Δh (h−s) value is an angular difference between an average value h (h), expressed in angle, of a h (15) value of the reflected light toward the 15° direction and a h (25) value of the reflected light toward the 25° direction and an average value h (s), expressed in angle, of a h (75) value of the reflected light toward the 75° direction and a h (110) value of the reflected light toward the 110° direction when the directions are based on the angular representation.

Advantageous Effects of Invention

The present invention provides a glitter pigment suitable for maintaining a brightness level of reflected light observed in a regular reflection direction and suitable for reducing an observation angle-dependent variation in reflected light, specifically, variations in brightness and color of reflected light.

