Azo Lake Pigments - Azo Lake Pigments

...When organic pigments are classified based on their chemical structure, there are azo pigments, which are mainly yellow to red, and phthalocyanine pigments, which are mostly blue to green. Others include metal complex pigments, triphenylmethane pigments, and modern pigments, the development of which has been vigorously pursued in recent years.
[Azo pigments]
Pigments containing the azo group -N=N- as a chromophore are classified into insoluble azo pigments that do not have hydrophilic groups such as carboxyl groups -COOH or sulfo groups -SO ₃ H in the molecule, and azo lake pigments that have water-soluble azo dyes that have these in the molecule and are insoluble in the form of calcium salts or barium salts. (1) Insoluble azo pigments (a) A series in which a diazo component without a hydrophilic group is coupled to β-naphthol, 2-hydroxy-3-naphthoic acid and its anilides (naphthol AS series) (Figure 1-a) These red to purple pigments have greater water and alkali resistance than azo lake pigments that have hydrophilic groups, and are also quite lightfast. …

*Some of the terminology that refers to "azo lake pigments" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…　有機顔料を化学構造から分類すると，黄色～赤色系の主体をなすアゾ顔料と，青色～緑色系のフタロシアニン系が多く，ほかに金属錯塩型顔料，トリフェニルメタン系顔料，また近年その開発が精力的に進められているモダンピグメントmodern pigmentsがある。
［アゾ顔料］
　発色団としてアゾ基－N＝N－を含む顔料で，カルボキシル基－COOH，スルホ基－SO₃Hなどの親水基を分子内にもたない不溶性アゾ顔料と，これを分子内にもつ水溶性アゾ色素をカルシウム塩，バリウム塩の形で不溶化したアゾレーキ顔料に分類される。(1)不溶性アゾ顔料　(a)親水基をもたないジアゾ成分をβ‐ナフトール，2‐ヒドロキシ‐3‐ナフトエ酸およびそのアニリド(ナフトールAS類)にカップリングした系統(図1-a)　赤色～紫色顔料で，親水基をもつアゾレーキに比べ耐水･耐アルカリ性が大きく，耐光性もかなり高い。…

※「アゾレーキ顔料」について言及している用語解説の一部を掲載しています。

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