JP3991857B2 - Thermosensitive recording medium containing crystal modification of developer n-butyl = 4- (3- (p-toluenesulfonyl) ureido) benzoate for thermal recording medium - Google Patents

Description

により表わされ、かつ、そのＸ線回折図において、Ｃｕ−Ｋα線による回折角（２θ）が５．７０°に強いピークを示し、かつ、１８ . １５°、２５ . ６０°に中間強度のピークを示す結晶形Ｉを有するｎ−ブチル＝４−（３−（ｐ−トルエンスルホニル）ウレイド）ベンゾエートの結晶変態を含有する感熱記録層を支持体上に設けた感熱記録体。
【００１０】
本発明者はＴＵＢＥが種々の安全性試験を高いレベルでクリアした、環境適性の高い顕色剤であるという特徴も見出した。
【００１１】
ＴＵＢＥは、特開２０００―３５５１６７号公報（特許文献１）において既に顕色剤として有用であることが開示されている。しかし、工場レベルの量産を行なうためには、顕色剤分散液の粘度等の物性が安定していることが必須であるが、同じ化学構造式を有するＴＵＢＥの中でも分散液が安定であるものと、増粘または凝固してしまうものが存在することが明らかになった。ここで、ＴＵＢＥが結晶変態を有し、その変態によって、物性が異なることが初めて明らかになった。
その後の研究により、ＴＵＢＥは少なくとも３種の結晶変態を有し、そのうちの２種は、それを用いて水系分散液を作成した場合、長期の保存や、高温下での保存でも安定性を失わないのに対し、１種の結晶変態は、前記の処理で安定性を失い、激しく凝集するという特性を有することを発見した。
【００１２】
すなわち、上記結晶形Ｉは、Ｘ線回折においてＣｕ−Ｋα線による回折角（２θ）が、５．７０°において強いピークを示し、かつ、１８.１５°、２５.６０°に中間強度のピークを示す結晶形を有するもので、安定な分散液を形成する。上記結晶形IIは、６.９０°において強いピークを示し、かつ１４.９０°、１９.５０°において中間強度のピークを示す結晶形を有するもので、安定な分散液を形成する。一方結晶形IIIはＸ線回折においてＣｕ−Ｋα線による回折角（２θ）が、８.２０°において強いピークを示し、かつ、１８.０５°に中間強度のピークを示す結晶形を有するもので、これは安定な分散液を形成しない。この分散液は、長期の保存では数ヶ月で，あるいは高温の保存では１日から数日で著しく増粘しあるいは分散液全体が固化する挙動を示し、感熱記録体用の塗工液調成に著しい問題を呈する。従って、事実上、工場レベルでの製造に適するものは、結晶形Ｉのものと、結晶形ＩＩのもの又は、それらの混合物を含有するものである。
【００１３】
ＴＵＢＥは、結晶形Ｉ、結晶形II、あるいは結晶形IIIを用いて分散液を調成し、それから感熱記録体を作成しても、その感熱記録体にはほとんど差がない。いずれも高性能の感熱記録体の特性を示す。同時に研究過程において結晶形ＩまたはIIを加熱するとさらに相転移を起こし、第４の結晶形IV（Cu−Kα線による回折角（２θ）が１９.５°に強いピークを示し、かつ、８.２５°、２２.０５°に中間強度のピークを示す）となる事がわかった。
従って、結晶形Ｉ、IIから出発しても画像印字操作（加熱）により結晶形IVに相転移をした後、融解し染料と反応して発色を生じている可能性もある。
【００１４】
本発明者らは、ＴＵＢＥにはいくつかの合成法があるが、その合成法と得られる結晶形態の間に強い相関関係があることを発見した。例えば、ブチル＝ｐ−アミノベンゾエートとｐ−トルエンスルホニルイソシアナートをアセトニトリル溶媒中で反応させて得られたＴＵＢＥは、結晶形ＩまたはIIの形態をとる。これに対して、同様の反応をたとえばトルエン中またはキシレン中で行なうと結晶形IIIの形態をとりやすい。
【００１５】
次にＴＵＢＥの結晶変態をＸ線回折図において解説する。図１〜３はＣｕ−Ｋα線による粉体Ｘ線回折法において、回折角（２θ）をシンチレーションカウンターを使用して記録したＸ線回折図である。
【００１６】
図１は結晶形ＩのＸ線回折図であり、回折角（２θ）の５．７０°に強いピークを示し、かつ１８.１５°、２５.６０°に中間強度のピークを示す。
【００１７】
図２は結晶形IIのＸ線回折図であり、回折角（２θ）の６.９０°に強いピークを示し、かつ１４.９０°、１９.５０°に中間強度のピークを示す。
【００１８】
図３は参考までに結晶形IIIのＸ線回折図であり、回折角（２θ）の８.２０°に強いピークを示し、かつ１８.０５°に中間強度のピークを示す。
【００１９】
これらＸ線回折図はＴＵＢＥの結晶変態を示し、各結晶変態の相違を明確に表示している。各結晶変態のＴＵＢＥは、通常はいずれも白色粉末状態であり、肉眼で見ただけではどの結晶変態なのか識別することは困難であるが、得られたものについてＸ線回折測定をすることによって明確に区別することができる。
【００２０】
不思議なことに、ＴＵＢＥは各結晶変態によってその融点はほとんど変わらない。この事実により、ＴＵＢＥの結晶変態は見逃されていた。
【００２１】
【実施例】
下記に実施例を示し、本発明を具体的に説明する。特に断らない限り、「部」および「％」は、それぞれ「重量部」および「重量％」を表す。
【００２２】
＜実施合成例１＞ ＴＵＢＥ結晶形Ｉの合成
滴下ロート、および温度計を装着した三口フラスコに、１９.３ｇ（０.１mol ）ブチル＝ｐ−アミノベンゾエートを入れ、これを１５０mlのアセトニトリルに溶解した。この溶液を撹拌しながら、これに滴下ロートより、ｐ−トルエンスルホニルイソシアナート２１.７ｇ（０.１１mol ）を滴下した。滴下開始と同時に発熱反応がおこった。得られた反応混合液を更に１時間７０℃加熱撹拌し、冷却後析出した白色結晶を濾過して３５．１ｇの目的物を得た。この白色結晶について、理学電機株式会社製のＸ線回折装置（商標：ガイガーフレックスＲＩＮＴ−２２００）により分析を行った。Ｃｕ−Ｋα線による粉体Ｘ線回折法で、回折角（２θ）をシンチレーションカウンターを使用して記録すると、図１に示されるようなＸ線回折図を与え、その融点は１５６.６℃であった。
【００２３】
＜実施合成例2 ＞ＴＵＢＥ結晶形IIの合成
滴下ロート、および温度計を装着した三口フラスコに、１９.３ｇ（０.１mol ）ブチル＝ｐ−アミノベンゾエートを入れ、これを１５０mlのアセトニトリルに溶解した。この溶液を撹拌しながら、これに滴下ロートより、ｐ−トルエンスルホニルイソシアナート２１.７ｇ（０.１１mol ）を滴下した。滴下開始と同時に発熱反応がおこった。得られた反応混合液を更に１時間７０℃加熱撹拌する。反応終了後、直ちに反応器を氷中につけ急冷し、冷却後析出した白色結晶を濾過して３６.２ｇの目的物を得た。この白色結晶について、理学電機株式会社製のＸ線回折装置（商標：ガイガーフレックスＲＩＮＴ−２２００）により分析を行った。Ｃｕ−Ｋα線による粉体Ｘ線回折法で、回折角（２θ）をシンチレーションカウンターを使用して記録すると、図２に示されるようなＸ線回折図を与え、その融点は１５４.０℃であった。
【００２４】
＜比較合成例１＞ ＴＵＢＥ結晶形IIIの合成
滴下ロート、および温度計を装着した三口フラスコに、１９.３ｇ（０.１mol ）ブチル＝ｐ−アミノベンゾエートを入れ、これを２００mlのトルエンに分散した。この懸濁液を撹拌しながら、これに滴下ロートより、ｐ−トルエンスルホニルイソシアナート２１.７ｇ（０.１１mol ）を滴下した。滴下開始と同時に発熱反応がおこった。得られた反応混合液を更に１時間１００℃加熱撹拌し、冷却後析出した白色結晶を濾過して３８.２ｇの目的物を得た。この白色結晶について、理学電機株式会社製のＸ線回折装置（商標：ガイガーフレックスＲＩＮＴ−２２００）により分析を行った。Ｃｕ−Ｋα線による粉体Ｘ線回折法で、回折角（２θ）をシンチレーションカウンターを使用して記録すると、図３に示されるようなＸ線回折図を与え、その融点は１５６.４℃であった。
【００２５】
＜比較合成例２＞ ＴＵＢＥ結晶形IIIの合成（その２）
滴下ロート、および温度計を装着した三口フラスコに、１９.３ｇ（０.１mol ）ブチル＝ｐ−アミノベンゾエートを入れ、これを２００mlのキシレンに分散した。この懸濁液を撹拌しながら、これに滴下ロートより、ｐ−トルエンスルホニルイソシアナート２１.７ｇ（０.１１mol ）を滴下した。滴下開始と同時に発熱反応がおこった。得られた反応混合液を更に１時間１００℃加熱撹拌し、冷却後析出した白色結晶を濾過して３７.８ｇの目的物を得た。この白色結晶について、理学電機株式会社製のＸ線回折装置（商標：ガイガーフレックスＲＩＮＴ−２２００）により分析を行った。Ｃｕ−Ｋα線による粉体Ｘ線回折法で、回折角（２θ）をシンチレーションカウンターを使用して記録すると、図3に示されるようなＸ線回折図を与え、その融点は１５６.４℃であった。
【００２６】
上記各ＴＵＢＥを用い、以下の手順により水系分散液を作成した。

【００２７】
上記組成物をアイメックス社製６筒式サンドグラインダーを用い、０.８ｍｍのビーズを分散媒体とし、平均粒径が１μｍ以下（粒径は島津製作所製 SALD-2000Jにより測定）になるまで粉砕した。
分散終了後、ビーズを分離してＴＵＢＥの水系分散液１を得た。この分散液を３ヶ月間室温で静置し、３ヵ月後に状態を観察した。また、一部をガラス製の器に移し、栓をして６０℃のチャンバーに１昼夜放置し、その後状態を観察した。結果を表１に示す。
【００２８】
＜実施例分散液Ｂ２の作成と安定性試験＞
実施例分散液B１の調成と同様の操作、試験を行なった。ただし、ＴＵＢＥは実施合成例２で合成され、 図２のＸ線回折図を与える結晶形IIのものを用いた。結果を表１に示す。
＜比較分散液Ｂ３の作成と安定性試験＞
実施例分散液１の調成と同様の操作、試験を行なった。ただし、ＴＵＢＥは比較合成例１で合成され、 図３のＸ線回折図を与える結晶形IIIのものを用いた。結果を表１に示す。
＜比較分散液Ｂ４の作成と安定性試験＞
実施例分散液１の調成と同様の操作、試験を行なった。ただし、ＴＵＢＥは比較合成例２で合成され、 図３のＸ線回折図を与える結晶形IIIのものを用いた。結果を表１に示す。
【００２９】
＜感熱記録紙作製実施例１＞
下記操作により感熱記録紙を作製した。
（１）顔料下塗り紙の調製焼成クレイ（商標：アンシレックス、ＥＮＧＥＬＨＡＲＤ社製）８５部を水３２０部に分散して得られた分散物に、スチレン／ブタジエン共重合物エマルジョン（固形分５０％）４０部と、１０％酸化でんぷん水溶液５０部とを混合して塗液を調製した。この塗液を４８ｇ／ｍ² の原紙の上に乾燥後の塗布量が７．０ｇ／ｍ² になるように塗工して、顔料下塗り紙を作製した。
【００３０】

上記組成物をサンドグラインダーを用い、平均粒径が１μｍ以下になるまで粉砕した。
【００３１】

上記組成物をサンドグラインダーを用い、平均粒径が１μｍ以下になるまで粉砕した。
【００３２】
（４）発色層の形成
感熱発色層の形成上記Ａ液６０部、上記分散液Ｂ１を１２０部、およびＣ液１２０部に、炭酸カルシウム顔料２６部、２５％ステアリン酸亜鉛分散液１２部、３０％パラフィン分散液１０部、および１０％ポリビニルアルコール水溶液８０部を混合、撹拌し、塗布液とした。この塗布液を、顔料下塗り紙の顔料塗工面に、乾燥後の塗布量が５．０ｇ／ｍ² となるように塗布乾燥して感熱発色層を形成し、感熱記録紙を作製した。
【００３３】
（５）スーパーカレンダー処理
カレンダー処理上記の様にして得られた感熱記録紙をスーパーカレンダーによって処理し、その表面の平滑度を８００〜１２００秒とした。
【００３４】
（６）発色試験
こうして得られた感熱記録紙の試料について、ハンター白色度計（東洋精機製作所）で白色度を測定した。次に大倉電機製動的感熱発色シミュレーターＴＨＰＭＤ（印字電圧２１．７Ｖ）を用い、印加パルス幅０.６ｍｓと１．０ｍｓの印字条件で試料を市松模様状に発色させた。発色濃度はマクベス反射濃度計ＲＤ−９１４で測定し、これを記録感度を代表する値とした。テスト結果を表２に示す
【００３５】
＜感熱記録紙作製実施例２＞
感熱記録紙作製例１と同様の操作を行なった。但し、分散液Ｂ１の代わりに分散液Ｂ２を用いた。テスト結果を表２に示す。
【００３６】
＜感熱記録紙作製比較例１＞
感熱記録紙作製例１と同様の操作を行なった。但し、分散液Ｂ１の代わりに分散液Ｂ３を用いた。テスト結果を表２に示す。
【００３７】
＜感熱記録紙作製比較例２＞
感熱記録紙作製例１と同様の操作を行なった。但し、分散液Ｂ１の代わりに分散液Ｂ４を用いた。テスト結果を表２に示す。
【００３８】
【表１】

「分散液凝固」とは、分散液全体が固化する状態をいう。
【表２】

安定性試験（高温処理、長時間保管）を行なわずに感熱記録塗料を調製し、感熱記録体を作成して試験した。
【００３９】
前記表１から明らかなように、本発明のＴＵＢＥの結晶形ＩおよびIIを用いた場合、水系分散液は長期の保存および高温の保存でも安定に存在する。しかし、結晶形IIIのＴＵＢＥを用いた場合、水系分散液は、長期の保存または高温の保存下で著しく増粘または、凝固し、塗料の調製ができない。しかし、表２より明らかなように、結晶形IIIのＴＵＢＥを用いても、分散後短時間は分散液は安定であり、それを用いて作成した感熱紙は結晶形Ｉ、またはIIを用いて作成した実施例の感熱紙同様、高い白色度と、高い発色感度を示し、顕色剤としての適性を示した。
【００４０】
【発明の効果】
本発明のＴＵＢＥの２種の新規な結晶変態は、それを用いて作成した水系分散液の安定性に優れ、かつその分散液を用いて作成した感熱紙の特性も高く、実用上極めて有用なものである。本発明の顕色剤は直接手に触れる感熱紙、オーバーコートを設けない感熱紙等にも用いることができる。
【図面の簡単な説明】
【図１】 図１は本発明顕色剤結晶形ＩのＸ線回折図であり、回折角（２θ）の５．７０°に強いピークを示し、かつ１８.１５°、２５.６０°に中間強度のピークを示す。
【図２】図２は本発明顕色剤結晶形IIのＸ線回折図であり、回折角（２θ）の６.９０°に強いピークを示し、かつ１４.９０°、１９.５０°に中間強度のピークを示す。
【図３】図３は本発明外顕色剤結晶形IIIのＸ線回折図であり、回折角（２θ）の８.２０°に強いピークを示し、かつ１８.０５°に中間強度のピークを示す。[0001]
BACKGROUND OF THE INVENTION
The present invention provides a novel crystal modification of n-butyl = 4- (3- (p-toluenesulfonyl) ureido) benzoate (hereinafter abbreviated as TUBE), which has a high industrial utility value as a developer for a thermal recording material. The present invention relates to a heat-sensitive recording material comprising a heat-sensitive recording layer contained on a support .
[0002]
[Prior art]
The heat-sensitive recording material is generally a color developing material such as an electron donating leuco dye and a color developing material such as an organic acid material such as an electron accepting phenolic compound on a support such as paper, synthetic paper or plastic film. Is provided as a main component, and a recorded image can be obtained by reacting them with heat energy. Such heat-sensitive recording materials are disclosed in, for example, Japanese Patent Publication No. 43-4160 and Japanese Patent Publication No. 45-14039, and are widely put into practical use.
[0003]
Because the recording device is compact, inexpensive, and easy to maintain, thermal recording media can be used for cash register sheets, transportation tickets, commuter pass tickets, handy terminal output papers, betting tickets, boat tickets, or ultrasound diagnostic image output. Widely used in paper.
In recent years, for the purpose of improving various properties related to the formation of this image, development and invention of a developer, that is, a so-called developer has been performed. They are disclosed in, for example, JP-A-5-32061, JP-A-5-147357, JP-A-8-333329, and JP-A-2000-355167 (Patent Document 1) and are put into practical use. Yes.
[0004]
Among these, when TUBE disclosed in Patent Document 1 is used as a developer, a heat-sensitive recording material having high recording sensitivity and high image storage stability can be produced.
[0005]
As described above, TUBE has excellent features as a developer for a thermal recording material, but it has been found that the physical properties of the resulting compound differ depending on the synthesis method and the like. This is considered to be a polymorphism / transformation phenomenon of crystals, but a clear characterization is required to produce a stable product. Furthermore, it is also important to create a technical base for manufacturing a heat-sensitive recording material having characteristics by actively utilizing the difference in physical properties between the crystals.
Crystal polymorphism is an unusual phenomenon, but it is not rare. Substances related to heat-sensitive recording materials are disclosed in Patent Documents 2 and 3 and the like. However, it is extremely difficult to predict which substance will cause crystal transformation, and the fact is that it depends on experimental facts.
[0006]
[Patent Document 1]
JP 2000-355167 A (page 2, claim 2)
[Patent Document 2]
JP-A-5-220301 (second page, claim 1)
[Patent Document 3]
Japanese Unexamined Patent Publication No. 7-278098 (second page, claim 1)
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a heat-sensitive recording material in which a heat-sensitive recording layer containing a novel crystal modification of TUBE useful as a color developing material of the heat-sensitive recording material is provided on a support .
[0008]
[Means for Solving the Problems]
The present invention includes the following embodiments.
[1] The following structural formula (I):
[Chemical formula 2]

Represented by, and, in its X-ray diffraction pattern, shows strong peaks at diffraction angles (2 [Theta]) is 5.70 ° by Cu-K [alpha line, and, 18. 15 °, 25. 60 ° to the intermediate intensity A heat-sensitive recording material, wherein a heat-sensitive recording layer containing a crystal modification of n-butyl = 4- (3- (p-toluenesulfonyl) ureido) benzoate having a crystal form I exhibiting a peak is provided on a support.
[0010]
The present inventor has also found out that TUBE is a developer with high environmental suitability that has cleared various safety tests at a high level.
[0011]
TUBE has already been disclosed in JP 2000-355167 A (Patent Document 1) as being useful as a developer. However, in order to carry out mass production at the factory level, it is essential that the physical properties such as the viscosity of the developer dispersion are stable, but among the TUBEs having the same chemical structural formula, the dispersion is stable. It became clear that there was something that thickened or coagulated. Here, it became clear for the first time that TUBE has a crystal transformation and the physical properties differ depending on the transformation.
Subsequent research shows that TUBE has at least three crystal transformations, two of which lose stability when stored for long periods of time or at high temperatures when they are used to make aqueous dispersions. while no one crystalline modification loses stability before Symbol treatment, it was found to have the property of violently aggregation.
[0012]
That is, the crystal form I shows a strong peak in the X-ray diffraction when the diffraction angle (2θ) by Cu-Kα ray is 5.70 °, and the intermediate intensity peaks at 18.15 ° and 25.60 °. And form a stable dispersion. The crystal form II has a strong peak at 6.90 ° and a peak of intermediate intensity at 14.90 ° and 19.50 °, and forms a stable dispersion. On the other hand, the crystal form III has a crystal form in which the diffraction angle (2θ) by Cu-Kα ray in X-ray diffraction shows a strong peak at 8.20 ° and an intermediate intensity peak at 18.05 °. This does not form a stable dispersion. This dispersion shows the behavior of thickening or solidifying the whole dispersion in several months for long-term storage or in one to several days for storage at high temperatures. Presents significant problems. Accordingly, those that are practically suitable for manufacturing at the factory level are those that contain crystalline Form I, crystalline Form II, or mixtures thereof.
[0013]
Even if TUBE prepares a dispersion using crystalline form I, crystalline form II, or crystalline form III, and makes a thermal recording body therefrom, there is almost no difference in the thermal recording body. Both show the characteristics of high-performance thermal recording media. At the same time, when the crystalline form I or II is heated in the course of the research, further phase transition occurs, and the fourth crystalline form IV (the diffraction angle (2θ) by Cu-Kα ray shows a strong peak at 19.5 °, and 8. It was found that the intermediate intensity peaks were observed at 25 ° and 22.05 °).
Therefore, even if starting from crystal forms I and II, there is a possibility that after phase transition to crystal form IV by image printing operation (heating), it melts and reacts with the dye to cause color development.
[0014]
The present inventors have found that there are several synthesis methods for TUBE, and there is a strong correlation between the synthesis method and the obtained crystal form. For example, TUBE obtained by reacting butyl = p-aminobenzoate and p-toluenesulfonyl isocyanate in an acetonitrile solvent takes the form of crystalline form I or II. On the other hand, when the same reaction is carried out in toluene or xylene, for example, it is easy to take the form of crystal form III.
[0015]
Next, the crystal transformation of TUBE will be explained using an X-ray diffraction diagram. 1 to 3 are X-ray diffraction diagrams in which a diffraction angle (2θ) is recorded using a scintillation counter in a powder X-ray diffraction method using Cu-Kα rays.
[0016]
FIG. 1 is an X-ray diffraction pattern of crystal form I, which shows a strong peak at a diffraction angle (2θ) of 5.70 °, and shows intermediate intensity peaks at 18.15 ° and 25.60 °.
[0017]
FIG. 2 is an X-ray diffraction diagram of crystal form II, showing a strong peak at a diffraction angle (2θ) of 6.90 °, and intermediate intensity peaks at 14.90 ° and 19.50 °.
[0018]
FIG. 3 is an X-ray diffraction diagram of crystal form III for reference, showing a strong peak at a diffraction angle (2θ) of 8.20 ° and a medium intensity peak at 18.05 °.
[0019]
These X-ray diffractograms show the crystal transformation of TUBE, and clearly show the difference between each crystal transformation. The TUBE of each crystal modification is usually in a white powder state, and it is difficult to identify which crystal modification is by visual observation. However, the obtained TUBE is measured by X-ray diffraction measurement. It can be clearly distinguished.
[0020]
Strangely, the melting point of TUBE hardly changes with each crystal transformation. Due to this fact, the crystal transformation of TUBE was overlooked.
[0021]
【Example】
The present invention will be specifically described with reference to the following examples. Unless otherwise specified, “parts” and “%” represent “parts by weight” and “% by weight”, respectively.
[0022]
Example Synthesis Example 1 19.3 g (0.1 mol) butyl = p-aminobenzoate was placed in a three-necked flask equipped with a TUBE crystal form I dropping funnel and a thermometer, and this was dissolved in 150 ml of acetonitrile. . While stirring this solution, 21.7 g (0.11 mol) of p-toluenesulfonyl isocyanate was added dropwise thereto from a dropping funnel. An exothermic reaction occurred simultaneously with the start of dropping. The obtained reaction mixture was further heated and stirred at 70 ° C. for 1 hour, and the white crystals deposited after cooling were filtered to obtain 35.1 g of the desired product. The white crystal was analyzed with an X-ray diffractometer (trademark: Geigerflex RINT-2200) manufactured by Rigaku Corporation. When the diffraction angle (2θ) is recorded using a scintillation counter by powder X-ray diffraction method using Cu-Kα ray, an X-ray diffraction diagram as shown in FIG. 1 is obtained, and its melting point is 156.6 ° C. there were.
[0023]
Example Synthesis Example 2 Synthesis of TUBE crystal form II 19.3 g (0.1 mol) of butyl p-aminobenzoate was placed in a three-necked flask equipped with a dropping funnel and a thermometer, and this was dissolved in 150 ml of acetonitrile. . While stirring this solution, 21.7 g (0.11 mol) of p-toluenesulfonyl isocyanate was added dropwise thereto from a dropping funnel. An exothermic reaction occurred simultaneously with the start of dropping. The resulting reaction mixture is further heated and stirred at 70 ° C. for 1 hour. Immediately after completion of the reaction, the reactor was put into ice and quenched, and the white crystals deposited after cooling were filtered to obtain 36.2 g of the desired product. The white crystal was analyzed with an X-ray diffractometer (trademark: Geigerflex RINT-2200) manufactured by Rigaku Corporation. When the diffraction angle (2θ) is recorded using a scintillation counter by powder X-ray diffraction method using Cu-Kα ray, an X-ray diffraction diagram as shown in FIG. 2 is obtained, and its melting point is 154.0 ° C. there were.
[0024]
Comparative Synthesis Example 1 19.3 g (0.1 mol) butyl = p-aminobenzoate was placed in a three-necked flask equipped with a TUBE crystal form III dropping funnel and a thermometer, and this was dispersed in 200 ml of toluene. . While this suspension was stirred, 21.7 g (0.11 mol) of p-toluenesulfonyl isocyanate was added dropwise thereto from a dropping funnel. An exothermic reaction occurred simultaneously with the start of dropping. The resulting reaction mixture was further heated and stirred at 100 ° C. for 1 hour, and the white crystals deposited after cooling were filtered to obtain 38.2 g of the desired product. The white crystal was analyzed with an X-ray diffractometer (trademark: Geigerflex RINT-2200) manufactured by Rigaku Corporation. When the diffraction angle (2θ) is recorded using a scintillation counter by powder X-ray diffraction method using Cu-Kα ray, an X-ray diffraction diagram as shown in FIG. 3 is obtained, and its melting point is 156.4 ° C. there were.
[0025]
<Comparative Synthesis Example 2> Synthesis of TUBE crystal form III (part 2)
In a three-necked flask equipped with a dropping funnel and a thermometer, 19.3 g (0.1 mol) butyl p-aminobenzoate was placed and dispersed in 200 ml of xylene. While this suspension was stirred, 21.7 g (0.11 mol) of p-toluenesulfonyl isocyanate was added dropwise thereto from a dropping funnel. An exothermic reaction occurred simultaneously with the start of dropping. The resulting reaction mixture was further heated and stirred at 100 ° C. for 1 hour, and the white crystals deposited after cooling were filtered to obtain 37.8 g of the desired product. The white crystal was analyzed with an X-ray diffractometer (trademark: Geigerflex RINT-2200) manufactured by Rigaku Corporation. When the diffraction angle (2θ) is recorded using a scintillation counter by the powder X-ray diffraction method using Cu-Kα rays, an X-ray diffraction diagram as shown in FIG. 3 is obtained, and its melting point is 156.4 ° C. there were.
[0026]
Using each of the above TUBEs, an aqueous dispersion was prepared by the following procedure.

[0027]
The above composition was pulverized using an Imex 6-cylinder sand grinder using 0.8 mm beads as a dispersion medium until the average particle size was 1 μm or less (the particle size was measured by SALD-2000J manufactured by Shimadzu Corporation).
After the dispersion was completed, the beads were separated to obtain an aqueous dispersion 1 of TUBE. This dispersion was allowed to stand at room temperature for 3 months, and the state was observed after 3 months. In addition, a part was transferred to a glass vessel, stoppered and left in a 60 ° C. chamber for one day, and then the state was observed. The results are shown in Table 1.
[0028]
<Preparation of Example Dispersion B2 and Stability Test>
The same operation and test as in the preparation of Example dispersion B1 were performed. However, TUBE was synthesized in Example of Synthesis Example 2 and used the crystal form II that gives the X-ray diffraction diagram of FIG. The results are shown in Table 1.
<Preparation of comparative dispersion B3 and stability test>
The same operation and test as in the preparation of Example Dispersion 1 were performed. However, TUBE was synthesized in Comparative Synthesis Example 1 and used was crystal form III which gives the X-ray diffraction diagram of FIG. The results are shown in Table 1.
<Preparation of comparative dispersion B4 and stability test>
The same operation and test as in the preparation of Example Dispersion 1 were performed. However, TUBE was synthesized in Comparative Synthesis Example 2 and used the crystal form III that gives the X-ray diffraction diagram of FIG. The results are shown in Table 1.
[0029]
<Thermal recording paper production example 1>
A thermal recording paper was prepared by the following operation.
(1) Preparation of pigment undercoat paper A styrene / butadiene copolymer emulsion (solid content 50%) was prepared by dispersing 85 parts of calcined clay (trade name: Ansilex, manufactured by ENGELHARD) in 320 parts of water. A coating solution was prepared by mixing 40 parts with 50 parts of a 10% aqueous oxidized starch solution. This coating solution was applied onto a 48 g / m ² base paper so that the coating amount after drying was 7.0 g / m ² , thereby preparing a pigment undercoat paper.
[0030]

The composition was pulverized using a sand grinder until the average particle size became 1 μm or less.
[0031]

The composition was pulverized using a sand grinder until the average particle size became 1 μm or less.
[0032]
(4) Formation of color-forming layer Formation of heat-sensitive color-developing layer 60 parts of liquid A, 120 parts of dispersion B1 and 120 parts of liquid C, 26 parts of calcium carbonate pigment, 12 parts of 25% zinc stearate dispersion, 30 10 parts of a paraffin dispersion and 80 parts of a 10% polyvinyl alcohol aqueous solution were mixed and stirred to obtain a coating solution. This coating solution was applied and dried on the pigment coated surface of the pigment undercoat paper so that the coating amount after drying was 5.0 g / m ² to form a heat-sensitive color forming layer, thereby producing a heat-sensitive recording paper.
[0033]
(5) Super calendar process calendar process The thermal recording paper obtained as mentioned above was processed with the super calendar, and the smoothness of the surface was made into 800-1200 second.
[0034]
(6) Color development test The sample of the thermal recording paper thus obtained was measured for whiteness with a Hunter whiteness meter (Toyo Seiki Seisakusho). Next, using a dynamic thermal coloring simulator THPMD (printing voltage 21.7 V) manufactured by Okura Electric, the sample was colored in a checkered pattern under printing conditions of applied pulse widths of 0.6 ms and 1.0 ms. The color density was measured with a Macbeth reflection densitometer RD-914, and this was a value representative of recording sensitivity. The test results are shown in Table 2. [0035]
<Example 2 for making thermal recording paper>
The same operation as in thermal recording paper preparation example 1 was performed. However, dispersion B2 was used instead of dispersion B1. The test results are shown in Table 2.
[0036]
<Thermal recording paper production comparative example 1>
The same operation as in thermal recording paper preparation example 1 was performed. However, dispersion B3 was used instead of dispersion B1. The test results are shown in Table 2.
[0037]
<Thermal recording paper production comparative example 2>
The same operation as in thermal recording paper preparation example 1 was performed. However, dispersion B4 was used instead of dispersion B1. The test results are shown in Table 2.
[0038]
[Table 1]

“Dispersion solidification” refers to a state in which the entire dispersion is solidified.
[Table 2]

A heat-sensitive recording paint was prepared without performing a stability test (high temperature treatment, long-term storage), and a heat-sensitive recording material was prepared and tested.
[0039]
As is apparent from Table 1, when the TUBE crystal forms I and II of the present invention are used, the aqueous dispersion stably exists even during long-term storage and high-temperature storage. However, when TUBE of crystalline form III is used, the aqueous dispersion is significantly thickened or solidified under long-term storage or storage at high temperature, and the paint cannot be prepared. However, as is apparent from Table 2, even when crystal form III TUBE is used, the dispersion is stable for a short time after dispersion, and the thermal paper made using the crystal form I or II uses crystal form I or II. Similar to the heat-sensitive paper of the prepared examples, it showed high whiteness and high color development sensitivity, and showed suitability as a developer.
[0040]
【The invention's effect】
The two new crystal modifications of TUBE of the present invention are excellent in stability of an aqueous dispersion prepared using the same, and have high characteristics of thermal paper prepared using the dispersion, and are extremely useful in practice. Is. The developer of the present invention can also be used for thermal paper that directly touches the hand, thermal paper without an overcoat, and the like.
[Brief description of the drawings]
FIG. 1 is an X-ray diffraction pattern of developer crystal form I of the present invention, showing a strong peak at 5.70 ° of diffraction angle (2θ) and at 18.15 ° and 25.60 °. A medium intensity peak is shown.
FIG. 2 is an X-ray diffraction pattern of the developer crystal form II of the present invention, showing a strong peak at a diffraction angle (2θ) of 6.90 °, and at 14.90 ° and 19.50 °. A medium intensity peak is shown.
FIG. 3 is an X-ray diffraction pattern of a developer crystal form III outside the present invention, showing a strong peak at a diffraction angle (2θ) of 8.20 ° and a medium intensity peak at 18.05 °. Indicates.

Claims (1)

The following structural formula (I):

In the X-ray diffraction diagram, the diffraction angle (2θ) by Cu-Kα ray shows a strong peak at 5.70 °, and 18 . 15 °, 25 . Thermal recording in which a thermal recording layer containing a crystal modification of n-butyl = 4- (3- (p-toluenesulfonyl) ureido) benzoate having a crystal form I showing an intermediate intensity peak at 60 ° is provided on a support. body.

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