JP4084022B2 - Near-infrared transmitting black azo pigment and pigment composition - Google Patents

Description

（なお、式中のＲは炭素数１〜３の低級アルキル基および炭素数１〜３の低級アルコキシル基からなる群から選ばれた少なくとも１種の基であり、ｎは１〜５の整数であり、ｎが２以上のときはＲは同じでも異なってもよい。）
【０００７】
【発明の実施の形態】
次に好ましい実施形態を挙げて本発明をさらに具体的に説明する。本発明の黒色アゾ顔料は、上記の一般式（１）で表される黒色アゾ顔料であり、その結晶形態が薄片紐状で、近赤外線を高透過率で透過することが特徴である。
【０００８】
上記の一般式（１）で示される黒色アゾ顔料自体は公知（特公平４−１５２６５号公報参照）であり、この顔料の結晶形態は、短い短冊状で、Ｘ線回折による回折角（２θ）２６°付近に最大の回折強度を示す。また、この結晶形態の顔料は、近赤外線の反射率は大きいが、透過率は小さい。
【０００９】
一方、本発明の黒色アゾ顔料は、Ｘ線回折による回折角（２θ）２６°付近には強い回折強度はなく、回折角（２θ）１３°〜１４°の間および２７°付近に強い回折強度を示し、近赤外線の反射率は小さいが、透過率は大きく、上記の公知の黒色アゾ顔料とは、結晶形態および近赤外線に対する挙動が相違する。
【００１０】
上記の公知の黒色アゾ顔料は、顔料合成時にジアゾ成分とカップリング成分を過不足なく使用し、カップリング成分を１種類用いて得られるものである。一方、上記の如き特徴を有する本発明の黒色アゾ顔料は、例えば、顔料合成時にジアゾ成分およびカップリング成分を、いずれか一方の成分が過剰又は不足となる比率で使用したり、複数の種類のカップリング成分を同時にカップリングさせることなどにより得ることができる。
【００１１】
本発明で使用する下記の式（２）で示されるジアゾ成分をジアゾ化する方法は、従来公知の芳香族アミンのジアゾ化法に準じて行なうことができる。例えば、上記ジアゾ成分の塩酸塩などの鉱酸塩の冷水溶液に亜硝酸ソーダ溶液を加えてジアゾ化する方法などの公知の方法が使用できる。
【００１２】
また、カップリング成分は、下記の一般式（３）で示される２−ヒドロキシ−１１Ｈ−ベンゾ［ａ］−カルバゾール−３−カルボキシフェニルアミドが使用される。置換基（下記の一般式（３）におけるＲ）およびその数（ｎ）は前記の通りである。カップリング成分の具体例としては、例えば、２−ヒドロキシ−Ｎ−（２′−メチル−４′−メトキシフェニル）−１１Ｈ−ベンゾ［ａ］−カルバゾール−３−カルボキシアミド、２−ヒドロキシ−Ｎ−（４′−メトキシフェニル）−１１Ｈ−ベンゾ［ａ］−カルバゾール−３−カルボキシアミド、２−ヒドロキシ−Ｎ−（２′−エチルフェニル）−１１Ｈ−ベンゾ［ａ］−カルバゾール−３−カルボキシアミドなどが挙げられる。
【００１３】

【００１４】
上記のジアゾ成分のジアゾニウム塩と上記のカップリング成分とを常法に従い、水媒体あるいはｏ−ジクロルベンゼンなどの有機溶媒媒体中で両者をカップリングさせることにより、上記の一般式（１）で表される黒色アゾ顔料が得られる。カップリングに際しては、上記のジアゾ成分およびカップリング成分はそれぞれ１種類が選択されて使用されるほか、２種類以上のカップリング成分を併用することができる。
【００１５】
前記の公知の黒色アゾ顔料は、カップリング反応時に上記のジアゾ成分のジアゾニウム塩とカップリング成分とを等当量で使用し、カップリング成分を１種類用いて得られるものである。一方、本発明の黒色アゾ顔料は、カップリング反応時に上記のカップリング成分をジアゾ成分の当量よりも不足する量又は過剰な量で使用するか、又はカップリング成分として置換基の異なる２種類以上を混合して使用することによって得られる。
【００１６】
いずれの場合も、例えば、ｏ−ジクロルベンゼン中でカップリングし、その後１７０℃にて４時間加熱して結晶化処理することによって本発明の黒色アゾ顔料が得られる。前記の公知の黒色アゾ顔料は、大小混在した短い短冊状の結晶形態を示し、Ｘ線回折による回折角（２θ）２６°付近に強い回折ピークを示すが、本発明の黒色アゾ顔料の結晶形態は、細い揃った薄片紐状を示し、回折角（２θ）１３°〜１４°の間および２７°付近に強い回折ピークを示す。本発明の黒色アゾ顔料の結晶形態は、長さが約０．５〜１μｍ、幅が約０．０３μｍの薄片紐状の結晶である。また、平均アスペクト比（長さ／幅）は１０以上である。
【００１７】
結晶形態が、短冊状から、薄片紐状に変わることにより、本発明の黒色アゾ顔料の近赤外線に対する透過率が向上することを見出した。この透過率の向上により、本発明の顔料を含む塗膜などを有する物体に近赤外線レーザーを照射した時、物体中を透過してレーザーの受光器に到達する光量は増加する。そのため受光器自体の感度が小さくても、レーザー光の検出感度は高くなって、レーザー光を十分感知でき、増幅やＳ／Ｎ比などの電気的制御が不必要となり、電気的な制御の要素を小さくすることができる。
【００１８】
また、例えば、カーボンブラックで着色された黒色インキと、カーボンブラック以外の黒色顔料で着色された黒色インキを併用して、肉眼では判別し得ない同一の黒色文字又は絵柄を印刷し、偽造防止用印刷物を印刷する場合がある。この場合、偽造されたと思われる印刷物の真贋の判定には、赤外線を照射してその反射率を測定する方法が使用される。すなわち、本物は、カーボンブラックで着色された黒色インキの印刷部分と、カーボンブラック以外の黒色顔料で着色された黒色インキの印刷部分（両者は肉眼では判別不能）とで、赤外線の反射率が異なるので本物と判断される。一方、カーボンブラックで着色された黒色インキのみで印刷された偽造物は、赤外線の反射率の差が認められない。このようにして印刷物の偽造防止が図られている。
【００１９】
上記の如き印刷物において、赤外線透過率が高い本発明の黒色アゾ顔料により着色されたインキによる印刷部分は、該印刷部分に赤外線が照射されると、赤外線は印刷層を透過して、下地（通常白色の紙など）で反射され、印刷層を再度通過して赤外線受光器で検出される。このように赤外線透過率の大きい本発明の黒色アゾ顔料を用いたインキは偽造防止用インキとして有用である。
【００２０】
また、本発明の黒色アゾ顔料を着色剤として使用した黒色塗料を建築物などの外壁や天井に塗布して塗膜を形成すると、太陽光線中の近赤外線が塗膜を通過して、白色の下地により反射され、再度塗膜を通過して外部に放散されるので、建築物などの室内の温度上昇を抑える遮熱塗料として使用することができる。
【００２１】
本発明の近赤外線透過性黒色アゾ顔料組成物は、上記の本発明の黒色アゾ顔料と赤外線透過性材料とを担体として含む顔料組成物であり、該顔料組成物の各種塗料、印刷インキあるいは記録材料などの製造に使用される。なお、本発明の顔料組成物には、本発明の目的が阻害されない範囲で、本発明の黒色アゾ顔料を補色するために、有彩色色素、白色顔料、他の黒色顔料又は体質顔料などを添加することができる。
【００２２】
有彩色色素として使用される色素としては、従来公知の有彩色顔料および有彩色染料が挙げられ、これらから適切に選択して使用する。具体的には、例えば、アゾ系顔料、アントラキノン系顔料、フタロシアニン系顔料、キナクリドン系顔料、ペリレン系顔料、アゾメチン系顔料、ピロール系顔料などの有機顔料などが挙げられる。
【００２３】
また、本発明の顔料組成物の担体として使用される近赤外線透過性材料としては、塗料、印刷インキなどの製造に従来から使用されているビヒクルなどが挙げられ、これらビヒクルは上記の用途で従来から使用されているものがいずれも使用可能であり、特に限定されるものではない。ビヒクル用樹脂としては、印刷インキにおいては、例えば、乾性油、ロジン、ギルソナイトなどの天然樹脂、石油樹脂、フェノール樹脂、アルキッド樹脂、ビニル樹脂、ポリアミド樹脂、アクリル樹脂、ニトロセルロースなどが使用される。
【００２４】
塗料におけるビヒクル用樹脂としては、例えば、上記の天然樹脂、アルキッド樹脂、アミノ樹脂、エポキシ樹脂、不飽和ポリエステル樹脂、ビニル樹脂、アクリル樹脂、ポリウレタン樹脂などが挙げられ、それぞれ従来から使用されている溶剤系および水性の形で使用する。これらの透明性担体と、本発明の黒色アゾ顔料との使用割合も、上記の各用途における各種顔料とビヒクルとの使用割合と同様であり、特に限定されない。
【００２５】
【実施例】
次に実施例および比較例を挙げて本発明を具体的に説明する。なお、文中、「部」または「％」とあるのは重量基準である。
【００２６】
実施例１
３．７５部（０．０１モル）の前記式（２）の化合物を、氷酢酸１１．３部に懸濁させ、これに濃塩酸３．７部を加えて攪拌した。これに水２．６部を加え、温度を０〜５℃に保ち、４０％亜硝酸ナトリウム水溶液２．０部を加え、約３０分間、同温度にて攪拌して黄色のジアゾニウム塩の溶液を得た。これに酢酸ナトリウム３水和物４．８部を加えてジアゾニウム塩の溶液を調製した。
【００２７】
一方、前記一般式（３）において置換基Ｒを有するフェニル基が２′−メチル−４′−メトキシフェニルである化合物３．５６部（０．００９モル）をｏ−ジクロルベンゼン２５０部中に懸濁させ、これに２０〜３０℃で上記ジアゾニウム塩溶液を加え、３０〜４０℃に保って氷酢酸２０部を加えた。この温度に５〜６時間保ってカップリングを行い、その後１７０℃にて４時間加熱して結晶化処理を行った。次いで、ろ過、メタノール洗浄、水洗、乾燥および粉砕して本発明の黒色アゾ顔料を得た。
【００２８】
この黒色アゾ顔料の結晶形態は、図１の３万倍透過型電子顕微鏡写真に示される薄片紐状であり、そのＸ線回折の結果は、回折角（２θ）１３．３５°および２６．８５°に強い回折ピークを示した（図４）。結晶の平均アスペクト比は１５であった。
【００２９】
比較例１
前記一般式（３）において置換基Ｒを有するフェニル基が２′−メチル−４′−メトキシフェニルである化合物の使用量を３．９６部（０．０１モル）に変える以外は実施例１と同様にして比較例の黒色アゾ顔料を得た。この黒色アゾ顔料は、図２の３万倍透過型電子顕微鏡写真に示される短い短冊状の結晶であり、Ｘ線回折の結果、回折角（２θ）２６．３０°に強い回折ピークを示した（図５）。結晶の平均アスペクト比は５であった。
【００３０】
実施例２
３．７５部（０．０１モル）の前記式（２）の化合物を、氷酢酸１１．３部に懸濁させ、これに濃塩酸３．７部を加えて攪拌した。これに水２．６部を加え温度を０〜５℃に保ち、さらに４０％亜硝酸ナトリウム水溶液２．０部を加え、約３０分間、同温度にて攪拌して黄色のジアゾニウム塩の溶液を得た。これに酢酸ナトリウム３水和物４．８部を加えてジアゾニウム塩の溶液を調製した。
【００３１】
一方、前記一般式（３）において置換基Ｒを有するフェニル基が２′−メチル−４′−メトキシフェニルである化合物２．７７部（０．００７モル）および前記一般式（３）において置換基Ｒを有するフェニル基が４′−メトキシフェニルである化合物１．５３部（０．００４モル）をｏ−ジクロルベンゼン２５０部中に懸濁させ、この懸濁液に２０〜３０℃で上記ジアゾニウム塩溶液を加え、３０〜４０℃に保って氷酢酸２０部を加えた。この温度に５〜６時間保ってカップリングを行い、その後１７０℃にて４時間加熱して結晶化処理を行った。次いで、ろ過、メタノール洗浄、水洗、乾燥および粉砕して本発明の黒色アゾ顔料を得た。
【００３２】
この黒色アゾ顔料の結晶形態は、図３の３万倍透過型電子顕微鏡写真に示される薄片紐状であり、Ｘ線回折の結果、回折角（２θ）１３．８５°および２６．９５°に強い回折ピークを示した（図６）。結晶の平均アスペクト比は２０であった。
【００３３】
使用例１
実施例１、２および比較例１の黒色アゾ顔料をそれぞれ用い、下記の配合処方に従って配合し、常法に従いガラスビーズを加えてペイントシェーカーを用いて分散させて３種の黒色塗料を作製した。実施例１の顔料を用いたものを塗料１とし、実施例２の顔料を用いたものを塗料２とし、比較例１の顔料を用いたものを塗料３とした。各塗料を、それぞれ石英ガラス板に２ｍｉｌアプリケーターで塗布し、常法に従い乾燥させて黒色塗膜を得た。この黒色塗膜の近赤外線（波長７００〜１，２００ｎｍ）透過率を３３０型自記分光光度計（日立製作所製）にて測定し、表１に示す結果が得られた。
【００３４】
＜配合処方＞
・黒色アゾ顔料（実施例１、２および比較例１の何れか１種） ５部
・アルキド樹脂（フタルキッド１３３−６０、日立化成社製） ６０部
・メラミン樹脂（スーパーベッカミンＪ８２０、大日本インキ社製） ２５部
・炭化水素系溶剤 １０部
合計 １００部
【００３５】

上記表１の結果から、本発明の黒色アゾ顔料は、近赤外線に対して高い透過率を示すことが分かる。
【００３６】
次に上記の各塗装ガラス板を用い、白バック（酸化マグネシュウム板）および黒バック（カーボンブラック板）で近赤外線（波長７００〜１，２００ｎｍ）反射率を３３０型自記分光光度計（日立製作所製）にて測定した。結果を表２に示す。なお、白バック反射率は、塗膜表面の反射率と塗膜を通った光の白バック面からの反射率との合計値であり、黒バック反射率は塗膜表面のみの反射率を示す。
【００３７】

上記表２の結果から、本発明の黒色アゾ顔料は、近赤外線に対して高い透過率を示し、赤外線反射率は低いことが分かる。
【００３８】
比較例２
使用例１と同様の方法でカーボンブラックを用いて黒色塗料４を作製した。
使用例２
前記塗料１、３および４をアルミ板（１５０ｍｍ×７０ｍｍ×０．１ｍｍ）にバーコーターＮｏ．４０を用いて塗布し、常法に従い乾燥させて３種の塗装板１、３および４を形成した。発泡スチロール製昇温テスト装置上に上記３種の黒色塗装板１、３および４を乗せ、該テスト板上の４００ｍｍ上から光（２５０Ｗ赤外線ランプ）を照射し、１、５、１０、２０および３０分間テスト板と槽内の温度を測定した。試験結果を表３に示す。本発明の顔料からなる塗装板１は、赤外線の透過率が塗装板３および４より大きいことにより、下地アルミ板での反射が大きく、塗装板３および４よりテスト板温度および槽内温度ともに低く遮熱性が大きい。
【００３９】

【００４０】
使用例３
下記処方にてオフセット平版印刷用黒色インキ１を調製した。
・実施例１で得た黒色アゾ顔料 ３０．０部
・オフセット平版インキ用調合ワニス ６１．７部
・ドライヤー ０．８部
・インキソルベント ７．５部
・合計 １００．０部
上記においてオフセット平版インキ用調合ワニスは、ロジン変性フェノール樹脂、乾性油変性イソフタル酸アルキッドおよび乾性油を主成分とし、インキソルベントおよびアルミニウムキレートを加えたものである。
【００４１】
別に下記の処方にてオフセット平版印刷用黒色インキ２を調製した。
・ファーネスタイプカーボンブラック ２３．０部
・オフセット平版インキ用調合ワニス ７１．２部
・ドライヤー ０．８部
・インキソルベント ５．０部
・合計 １００．０部
上記で得たインキ１および２を用いてアート紙にオフセット印刷機にて、スクリーン線数を１５０線で平網濃度１００％にて全面印刷し、黒色の印刷紙１および２を得た。
【００４２】
この印刷紙１および２は見た目には同じ黒色であるが、赤外線フィルムで撮影すると印刷紙１はほぼ白色に撮影され、一方、印刷紙２は黒色に撮影される。このように印刷紙１および２は可視光線では同じ黒色であるが、赤外線フィルム撮影では明らかに異なる白色と黒色とに撮影される。この特性を利用し、本発明の顔料は偽造防止目的のインキの顔料として有用である。
【００４３】
【発明の効果】
以上の本発明によれば、化学構造が同一の公知の黒色アゾ顔料（近赤外線反射率が大きく、近赤外線透過率は小さい）とは異なり、近赤外線反射率が小さく、近赤外線透過率が大きい黒色アゾ顔料が提供される。
本発明の黒色アゾ顔料は、自動車や建材などの昇温防止用塗料や農業用寒冷紗用の塗料や電子部品の塗料用の着色剤として、また、赤外線通信、赤外線迷彩、光学フィルター、偽造防止目的の着色剤などとして有用である。
【図面の簡単な説明】
【図１】 実施例１の黒色アゾ顔料の透過型電子顕微鏡写真。スケールは１μｍを表わす。
【図２】 比較例１の黒色アゾ顔料の透過型電子顕微鏡写真。スケールは１μｍを表わす。
【図３】 実施例２の黒色アゾ顔料の透過型電子顕微鏡写真。スケールは１μｍを表わす。
【図４】 実施例１の黒色アゾ顔料のＸ線回折図。
【図５】 比較例１の黒色アゾ顔料のＸ線回折図。
【図６】 実施例２の黒色アゾ顔料のＸ線回折図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a near-infrared transmissive black azo pigment and a black azo pigment composition containing the same. In the present invention, “near infrared” refers to light having a wavelength of 800 to 2,000 nm.
[0002]
[Prior art]
Conventionally, carbon black, aniline black, iron oxide black, and the like have been used as black pigments. These pigments absorb light of wavelengths from the ultraviolet region to the far infrared region, are not transmissive to near infrared light, are easy to absorb infrared rays, that is, heat rays, and objects colored with these pigments are directly irradiated. It tends to become hot due to sunlight. Further, these conventional black pigments have a property of poor electrical insulation when used as a colorant for paints for electronic parts.
[0003]
In recent years, with the development of lasers, particularly semiconductor lasers and sensors therefor, there has been an increasing demand for black pigments having properties that are not found in black pigments such as carbon black and aniline black that have been conventionally used. For example, such fields include infrared communication using black pigments, infrared camouflage, optical filters, anti-counterfeiting printing, etc., paints for electronic components, paints for preventing temperature rise of automobiles or building materials, agricultural refrigeration And the coloring agent field.
[0004]
[Problems to be solved by the invention]
Carbon black, aniline black, etc. absorb light of wavelengths from the ultraviolet region to the far infrared region, and have been used as a black pigment for various coloring applications. However, they have poor electrical insulation and are used for coloring electrical components. There was a disadvantage that was not suitable. Such properties are essential to these pigments themselves and cannot be improved, and there is a demand for black pigments that do not have such drawbacks, that is, have high near-infrared transmittance.
[0005]
Accordingly, an object of the present invention is to provide a black pigment that can be used for coloring electrical components and the like and transmits near infrared rays with high transmittance, and a pigment composition using the black pigment as a colorant.
As a result of intensive studies to achieve the above object, the present inventor has made the crystal form of a specific black azo pigment into a thin string, so that even if the long diameter (length) is 1 μm or more, the transmission of near infrared rays The inventors have found that the rate is increased, and have completed the present invention based on this finding.
[0006]
[Means for Solving the Problems]
The above object can be achieved by the present invention described below. That is, the present invention provides a near-infrared transmissive black azo pigment represented by the following general formula (1) and characterized in that the crystal form is a thin string, and a pigment composition containing the pigment.

(In the formula, R is at least one group selected from the group consisting of a lower alkyl group having 1 to 3 carbon atoms and a lower alkoxy group having 1 to 3 carbon atoms, and n is an integer of 1 to 5). Yes, when n is 2 or more, R may be the same or different.)
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described more specifically with reference to preferred embodiments. The black azo pigment of the present invention is a black azo pigment represented by the above general formula (1), and is characterized in that its crystal form is a thin string and transmits near infrared rays with high transmittance.
[0008]
The black azo pigment itself represented by the above general formula (1) is known (see Japanese Patent Publication No. 4-15265), and the crystal form of this pigment is a short strip, and the diffraction angle (2θ) by X-ray diffraction. The maximum diffraction intensity is shown around 26 °. Further, this crystal form pigment has a high near-infrared reflectance but a low transmittance.
[0009]
On the other hand, the black azo pigment of the present invention has no strong diffraction intensity near the diffraction angle (2θ) of 26 ° by X-ray diffraction, and strong diffraction intensity between the diffraction angle (2θ) of 13 ° to 14 ° and around 27 °. The reflectance of the near infrared ray is small, but the transmittance is large, and the behavior of the crystal form and the near infrared ray is different from the known black azo pigment.
[0010]
The known black azo pigment is obtained by using a diazo component and a coupling component without excess or deficiency during pigment synthesis and using one type of coupling component. On the other hand, the black azo pigment of the present invention having the above-described characteristics can be obtained by using, for example, a diazo component and a coupling component at a ratio in which either one component is excessive or insufficient at the time of pigment synthesis, It can be obtained by coupling the coupling components simultaneously.
[0011]
The method of diazotizing the diazo component represented by the following formula (2) used in the present invention can be carried out according to a conventionally known diazotization method of an aromatic amine. For example, a known method such as a method of diazotization by adding a sodium nitrite solution to a cold aqueous solution of a mineral salt such as hydrochloride of the diazo component can be used.
[0012]
As the coupling component, 2-hydroxy-11H-benzo [a] -carbazole-3-carboxyphenylamide represented by the following general formula (3) is used. The substituents (R in the following general formula (3)) and the number (n) are as described above. Specific examples of the coupling component include, for example, 2-hydroxy-N- (2′-methyl-4′-methoxyphenyl) -11H-benzo [a] -carbazole-3-carboxamide, 2-hydroxy-N—. (4'-methoxyphenyl) -11H-benzo [a] -carbazole-3-carboxamide, 2-hydroxy-N- (2'-ethylphenyl) -11H-benzo [a] -carbazole-3-carboxamide, etc. Is mentioned.
[0013]

[0014]
By coupling the diazonium salt of the diazo component and the coupling component in an aqueous medium or an organic solvent medium such as o-dichlorobenzene according to a conventional method, the above general formula (1) The black azo pigment represented is obtained. In coupling, one kind of each of the diazo component and the coupling component is selected and used, and two or more kinds of coupling components can be used in combination.
[0015]
The known black azo pigment is obtained by using the diazonium salt of the diazo component and the coupling component in an equivalent amount during the coupling reaction, and using one type of coupling component. On the other hand, the black azo pigment of the present invention uses the above-mentioned coupling component in an amount that is deficient or in excess of the equivalent of the diazo component during the coupling reaction, or two or more types having different substituents as the coupling component Can be obtained by mixing and using.
[0016]
In either case, for example, the black azo pigment of the present invention can be obtained by coupling in o-dichlorobenzene, followed by crystallization by heating at 170 ° C. for 4 hours. The known black azo pigment has a short strip-like crystal form mixed in size and exhibits a strong diffraction peak near a diffraction angle (2θ) of 26 ° by X-ray diffraction, but the crystal form of the black azo pigment of the present invention Shows a thin and uniform thin string shape, and shows a strong diffraction peak at diffraction angles (2θ) between 13 ° and 14 ° and in the vicinity of 27 °. The crystal form of the black azo pigment of the present invention is a thin string-like crystal having a length of about 0.5 to 1 μm and a width of about 0.03 μm. The average aspect ratio (length / width) is 10 or more.
[0017]
It has been found that the transmittance of the black azo pigment of the present invention to near infrared rays is improved by changing the crystal form from a strip shape to a thin string shape. By improving the transmittance, when an object having a coating film containing the pigment of the present invention is irradiated with a near-infrared laser, the amount of light transmitted through the object and reaching the laser receiver increases. Therefore, even if the sensitivity of the photoreceiver itself is small, the detection sensitivity of the laser beam is high, the laser beam can be sufficiently detected, and electrical control such as amplification and S / N ratio is unnecessary, and the electrical control element Can be reduced.
[0018]
Also, for example, using black ink colored with carbon black and black ink colored with a black pigment other than carbon black, the same black letters or patterns that cannot be discerned with the naked eye are printed to prevent counterfeiting. A printed material may be printed. In this case, a method of measuring the reflectance by irradiating infrared rays is used to determine the authenticity of the printed matter that seems to be forged. In other words, the reflectance of infrared rays is different between the printed part of black ink colored with carbon black and the printed part of black ink colored with a black pigment other than carbon black (both are indistinguishable with the naked eye). So it is judged to be genuine. On the other hand, a counterfeit printed with only black ink colored with carbon black shows no difference in infrared reflectance. Thus, forgery prevention of printed matter is achieved.
[0019]
In the printed matter as described above, when a printed portion of the ink colored with the black azo pigment of the present invention having a high infrared transmittance is irradiated with infrared rays, the infrared rays are transmitted through the printing layer and the base (usually normal White paper, etc.), passes through the printed layer again, and is detected by the infrared receiver. Thus, the ink using the black azo pigment of the present invention having a large infrared transmittance is useful as an anti-counterfeit ink.
[0020]
Moreover, when a black paint using the black azo pigment of the present invention as a colorant is applied to an outer wall or ceiling of a building or the like to form a coating film, near infrared rays in sunlight pass through the coating film, Since it is reflected by the groundwork, passes through the coating film again, and is diffused to the outside, it can be used as a thermal barrier paint that suppresses the temperature rise in the room such as a building.
[0021]
The near-infrared transmissive black azo pigment composition of the present invention is a pigment composition comprising the above-described black azo pigment of the present invention and an infrared transmissive material as carriers, and various paints, printing inks or recordings of the pigment composition. Used for manufacturing materials. In addition, to the pigment composition of the present invention, chromatic dye, white pigment, other black pigment or extender pigment, etc. are added in order to complement the black azo pigment of the present invention within the range where the object of the present invention is not hindered. can do.
[0022]
Examples of the chromatic colorant include conventionally known chromatic color pigments and chromatic color dyes, which are appropriately selected and used. Specific examples include organic pigments such as azo pigments, anthraquinone pigments, phthalocyanine pigments, quinacridone pigments, perylene pigments, azomethine pigments, and pyrrole pigments.
[0023]
Further, examples of the near-infrared transmitting material used as the carrier of the pigment composition of the present invention include vehicles conventionally used in the production of paints, printing inks, etc., and these vehicles are conventionally used in the above-mentioned applications. Any of those used from the above can be used, and is not particularly limited. As the vehicle resin, for example, natural resins such as drying oil, rosin, and gilsonite, petroleum resins, phenol resins, alkyd resins, vinyl resins, polyamide resins, acrylic resins, and nitrocellulose are used in printing inks.
[0024]
Examples of the vehicle resin in the paint include the above-mentioned natural resins, alkyd resins, amino resins, epoxy resins, unsaturated polyester resins, vinyl resins, acrylic resins, polyurethane resins, and the like. Used in system and aqueous form. The use ratio of these transparent carriers and the black azo pigment of the present invention is also not particularly limited, and is the same as the use ratio of various pigments and vehicles in each of the above applications.
[0025]
【Example】
Next, the present invention will be specifically described with reference to examples and comparative examples. In the text, “part” or “%” is based on weight.
[0026]
Example 1
3.75 parts (0.01 mol) of the compound of the formula (2) was suspended in 11.3 parts of glacial acetic acid, and 3.7 parts of concentrated hydrochloric acid was added thereto and stirred. 2.6 parts of water was added thereto, the temperature was kept at 0 to 5 ° C., 2.0 parts of 40% aqueous sodium nitrite solution was added, and the mixture was stirred at the same temperature for about 30 minutes to prepare a yellow diazonium salt solution. Obtained. To this was added 4.8 parts of sodium acetate trihydrate to prepare a diazonium salt solution.
[0027]
On the other hand, 3.56 parts (0.009 mol) of the compound in which the phenyl group having the substituent R in the general formula (3) is 2'-methyl-4'-methoxyphenyl is added to 250 parts of o-dichlorobenzene. The diazonium salt solution was added to the suspension at 20 to 30 ° C, and 20 parts of glacial acetic acid was added while maintaining the temperature at 30 to 40 ° C. Coupling was carried out while maintaining at this temperature for 5 to 6 hours, and then crystallization was performed by heating at 170 ° C. for 4 hours. Subsequently, the black azo pigment of the present invention was obtained by filtration, washing with methanol, washing with water, drying and grinding.
[0028]
The crystal form of the black azo pigment is a thin string shown in the 30,000 times transmission electron micrograph of FIG. 1, and the X-ray diffraction results are as follows: diffraction angles (2θ) of 13.35 ° and 26.85. A strong diffraction peak was shown at ° (FIG. 4). The average aspect ratio of the crystal was 15.
[0029]
Comparative Example 1
Example 1 except that the amount of the compound in which the phenyl group having the substituent R in the general formula (3) is 2'-methyl-4'-methoxyphenyl is changed to 3.96 parts (0.01 mol) Similarly, a black azo pigment of a comparative example was obtained. This black azo pigment is a short strip-like crystal shown in the 30,000 times transmission electron micrograph of FIG. 2, and showed a strong diffraction peak at a diffraction angle (2θ) of 26.30 ° as a result of X-ray diffraction. (FIG. 5). The average aspect ratio of the crystals was 5.
[0030]
Example 2
3.75 parts (0.01 mol) of the compound of the formula (2) was suspended in 11.3 parts of glacial acetic acid, and 3.7 parts of concentrated hydrochloric acid was added thereto and stirred. To this was added 2.6 parts of water, the temperature was kept at 0 to 5 ° C., and 2.0 parts of 40% sodium nitrite aqueous solution was further added, and stirred at the same temperature for about 30 minutes to obtain a yellow diazonium salt solution. Obtained. To this was added 4.8 parts of sodium acetate trihydrate to prepare a diazonium salt solution.
[0031]
On the other hand, 2.77 parts (0.007 mol) of the compound in which the phenyl group having the substituent R in the general formula (3) is 2′-methyl-4′-methoxyphenyl and the substituent in the general formula (3) 1.53 parts (0.004 mol) of a compound in which the phenyl group having R is 4'-methoxyphenyl is suspended in 250 parts of o-dichlorobenzene, and the above diazonium is suspended in this suspension at 20-30 ° C. A salt solution was added and 20 parts of glacial acetic acid was added, keeping at 30-40 ° C. Coupling was carried out while maintaining at this temperature for 5 to 6 hours, and then crystallization was performed by heating at 170 ° C. for 4 hours. Subsequently, the black azo pigment of the present invention was obtained by filtration, washing with methanol, washing with water, drying and grinding.
[0032]
The crystal form of the black azo pigment is a thin string shown in the 30,000 times transmission electron micrograph of FIG. 3, and as a result of X-ray diffraction, diffraction angles (2θ) of 13.85 ° and 26.95 ° are obtained. A strong diffraction peak was shown (FIG. 6). The average aspect ratio of the crystal was 20.
[0033]
Example 1
Using each of the black azo pigments of Examples 1 and 2 and Comparative Example 1, they were blended according to the following blending recipe, glass beads were added according to a conventional method, and dispersed using a paint shaker to prepare three kinds of black paints. The paint using the pigment of Example 1 was named paint 1, the paint using the pigment of Example 2 was paint 2, and the paint using the pigment of Comparative Example 1 was paint 3. Each paint was applied to a quartz glass plate with a 2 mil applicator and dried according to a conventional method to obtain a black coating film. The near-infrared (wavelength 700 to 1,200 nm) transmittance of this black coating film was measured with a 330-type self-recording spectrophotometer (manufactured by Hitachi, Ltd.), and the results shown in Table 1 were obtained.
[0034]
<Combination prescription>
Black azo pigment (any one of Examples 1 and 2 and Comparative Example 1) 5 parts Alkyd resin (Phthalkid 133-60, manufactured by Hitachi Chemical Co., Ltd.) 60 parts Melamine resin (Super Becamine J820, Dai Nippon Ink) 25 parts)
・ Hydrocarbon solvent 10 parts Total 100 parts

From the results of Table 1 above, it can be seen that the black azo pigment of the present invention exhibits high transmittance to near infrared rays.
[0036]
Next, using each of the painted glass plates described above, a white back (magnesium oxide plate) and black back (carbon black plate) with a near infrared (wavelength 700 to 1,200 nm) reflectivity of 330 type self-recording spectrophotometer (manufactured by Hitachi, Ltd.) ). The results are shown in Table 2. The white background reflectance is the total value of the reflectance of the coating film surface and the reflectance from the white background surface of the light passing through the coating film, and the black background reflectance represents the reflectance of only the coating film surface. .
[0037]

From the results in Table 2 above, it can be seen that the black azo pigment of the present invention exhibits high transmittance for near infrared rays and low infrared reflectance.
[0038]
Comparative Example 2
A black paint 4 was produced using carbon black in the same manner as in Use Example 1.
Example 2
The paints 1, 3 and 4 were coated on an aluminum plate (150 mm × 70 mm × 0.1 mm) with a bar coater No. 40 was applied and dried according to a conventional method to form three kinds of coated plates 1, 3 and 4. The above three kinds of black painted plates 1, 3 and 4 are placed on a temperature rising test device made of polystyrene foam, and light (250 W infrared lamp) is irradiated from 400 mm above the test plate, and 1, 5, 10, 20 and 30 are applied. The temperature in the test plate and the tank was measured for a minute. The test results are shown in Table 3. The coated plate 1 made of the pigment of the present invention has a higher infrared transmittance than the coated plates 3 and 4, so that the reflection on the base aluminum plate is large, and both the test plate temperature and the bath temperature are lower than the painted plates 3 and 4. Great heat insulation.
[0039]

[0040]
Example 3
A black ink 1 for offset lithographic printing was prepared according to the following formulation.
-Black azo pigment obtained in Example 1 30.0 parts-Formulation varnish for offset lithographic ink 61.7 parts-Dryer 0.8 parts- Ink solvent 7.5 parts -Total 100.0 parts The compound varnish is composed mainly of rosin-modified phenolic resin, drying oil-modified isophthalic acid alkyd and drying oil, and is added with ink solvent and aluminum chelate.
[0041]
Separately, black ink 2 for offset lithographic printing was prepared according to the following formulation.
-Furnace type carbon black 23.0 parts-Formulation varnish for offset lithographic ink 71.2 parts-Dryer 0.8 parts- Ink solvent 5.0 parts -Total 100.0 parts Using inks 1 and 2 obtained above Black paper 1 and 2 were obtained by printing the entire surface of art paper with an offset printer at a screen line number of 150 and a flat screen density of 100%.
[0042]
The printed papers 1 and 2 are visually the same black, but when photographed with an infrared film, the printed paper 1 is photographed almost white, while the printed paper 2 is photographed black. Thus, although the printing papers 1 and 2 are the same black in visible light, they are photographed in white and black that are clearly different in infrared film photography. Utilizing this characteristic, the pigment of the present invention is useful as a pigment for ink for the purpose of preventing counterfeiting.
[0043]
【The invention's effect】
According to the present invention described above, unlike known black azo pigments having the same chemical structure (high near-infrared reflectance and low near-infrared transmittance), the near-infrared reflectance is small and the near-infrared transmittance is large. A black azo pigment is provided.
The black azo pigment of the present invention is used as a colorant for paints for preventing temperature rise of automobiles, building materials, agricultural refrigeration paints, and electronic parts, and for infrared communication, infrared camouflage, optical filters, anti-counterfeiting. It is useful as a coloring agent.
[Brief description of the drawings]
1 is a transmission electron micrograph of the black azo pigment of Example 1. FIG. The scale represents 1 μm.
2 is a transmission electron micrograph of the black azo pigment of Comparative Example 1. FIG. The scale represents 1 μm.
3 is a transmission electron micrograph of the black azo pigment of Example 2. FIG. The scale represents 1 μm.
4 is an X-ray diffraction pattern of the black azo pigment of Example 1. FIG.
5 is an X-ray diffraction pattern of a black azo pigment of Comparative Example 1. FIG.
6 is an X-ray diffraction pattern of the black azo pigment of Example 2. FIG.

Claims (5)

A near-infrared transmissive black azo pigment represented by the following general formula (1), wherein the crystal form is a thin string shape.

(In the formula, R is at least one group selected from the group consisting of lower alkyl groups having 1 to 3 carbon atoms and lower alkoxyl groups having 1 to 3 carbon atoms, and n is an integer of 1 to 5) , N may be the same or different when n is 2 or more.) The black azo pigment according to claim 1, which exhibits a strong diffraction intensity at a diffraction angle (2θ) of 13 ° to 14 ° and around 27 ° by X-ray diffraction. The black azo pigment according to claim 1, wherein the average aspect ratio of the crystal is 10 or more. A near-infrared transmissive black azo pigment composition containing the black azo pigment according to claim 1 and having a near-infrared transmissive material as a carrier. Furthermore, the pigment composition of Claim 4 containing the pigment chosen from a chromatic color pigment, a white pigment, another black pigment, and an extender pigment.

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