JP4187299B2 - Titanium dioxide for coating and production method thereof, coating liquid for forming titanium dioxide coating, coating agent and food - Google Patents
Titanium dioxide for coating and production method thereof, coating liquid for forming titanium dioxide coating, coating agent and food Download PDFInfo
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- titanium dioxide
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- dihydrogen phosphate
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Description
【０００１】
【産業上の利用分野】
本発明は、タブレット状の薬剤や食品等の表面を被覆するコーティング層を白色とする二酸化チタンに係り、特に、耐変色性を向上させて白色を長寿命化させる改良に関する。
【０００２】
【従来の技術】
例えば、錠剤の形態をなす薬剤は、薬剤自体の苦みや色を隠蔽して服用しやすくするために、中核錠にコーティング層が被覆された錠剤が多い。このようなコーティング層は、主として、砂糖もしくはセルロースと結合剤および水から構成されるコーティング液を固化させたものが一般的である。なお、以下の説明で、砂糖や白糖含有と特定する場合のコーティング層を糖衣層と称し、セルロース含有と特定する場合のコーティング層をフィルム層と称する。結合剤は、薬剤や食品素材である中核錠との結合力を高めるもので、特開平９−２５２４５号公報に開示されているように、ゼラチン、寒天あるいはアラビアガム等が使用されている。また、コーティング層は、使用目的に応じて様々な色に着色され、そのために着色剤も添加されている。特に薬剤の場合は白色が多く、コーティング層を白色にする着色剤としては、特開平９−２５２４５号公報に開示されているように、馬鈴薯、とうもろこし、小麦粉、米等の澱粉類、炭酸カルシウム、タルク、二酸化チタン等がある。これらの中でも、無機白色顔料である二酸化チタンは、白色度、隠蔽力、着色力などの光学的性質に優れている。この二酸化チタンは、結晶構造の違いからルチル形とアナタース形とに大別され、特にルチル形二酸化チタンは耐候性に富むことから、薬剤用コーティング層の着色剤として広く使用されている。
【０００３】
【発明が解決しようとする課題】
ところが、本発明者によれば、白糖もしくはセルロースと二酸化チタンを水に混合して調整したコーティング液を薬剤等の中核錠に被覆してコーティング錠とし、このコーティング錠を自然光下あるいは紫外線下に放置したところ、経時変化により表面が青灰色に変色する（以下、この青灰色に変色することを単に変色と称する）ものがあることが確認された。この変色は、自然光に含まれる紫外線が二酸化チタンに照射されて二酸化チタンから酸素が脱離し、コーティング層中の二酸化チタンの一部が亜酸化物に変化したためと推定される。すなわち、光学的性質に優れた二酸化チタンをコーティング層の着色剤としても、経時的に変色が生じる場合があり、商品価値の低下を招くおそれがあることが判明した。
よって本発明は、コーティング層が経時変化によって変色せず、長期にわたって白色が保持され得るコーティング用二酸化チタンを提供することを目的としている。
【０００４】
【課題を解決するための手段】
上記のように、コーティング層の変色は二酸化チタンの光触媒作用に喚起されて生じるとの推定に基づき、発明者らは、この光触媒作用を抑制する手段について鋭意研究を重ねた結果、リン酸塩処理した二酸化チタンを添加したコーティング液によりコーティング層を形成したところ、自然光下あるいは紫外線下に放置しても変色が生じないことを見い出した。
本発明はこのような知見に基づいてなされたもので、中核錠のコーティング層を形成するコーティング用二酸化チタンであって、リン酸二水素カリウムまたはピロリン酸ナトリウムで処理され、コーティング中のリン酸二水素カリウムまたはピロリン酸ナトリウムの濃度が０．１〜１．０ｗｔ％であることを特徴としている。
【０００５】
上記リン酸塩の濃度は変色に関わってくるので適切な規定が必要であり、０．１〜１．０ｗｔ％の濃度が好ましく、０．５〜０．９ｗｔ％であればより好ましい。この範囲以下では二酸化チタンが変色し、また、この範囲以上ではリン酸塩自身が変色の原因となる可能性がある。
また、使用される二酸化チタンは微粉状であり、コーティング液に分散・混合されること、着色力、隠蔽力等の顔料特性が求められること、さらには実際に口にふくんだ際の舌触りあるいは嚥下する際に不快感を覚えないことを考慮すると、その粒径は０．１〜０．８μｍ程度が確保されていれば好適であり、０．２〜０．４μｍであればより好ましい。
【０００６】
【発明の実施の形態】
以下、本発明のより好ましい実施の形態について説明する。
（１）二酸化チタン
コーティング層を構成する二酸化チタンは、体内に摂取されるため、日本薬局方の規定を満足する高純度二酸化チタンが要求される。本発明においても、日本薬局方の基準を満足した高純度二酸化チタン粉（東邦チタニウム社製）を使用した。また、二酸化チタンの好ましい平均粒径は０．２〜０．４μｍであり、コーティング液への十分な分散・混合性や、実際に口にふくんだ際の舌触りあるいは嚥下する際に不快感を覚えないことを満足するレベルが確保されている。なお、粒径は電子顕微鏡写真に基づいて測定した。
【０００７】
（２）リン酸塩およびリン酸塩による二酸化チタンの表面処理
二酸化チタンの表面処理用として、本実施の形態では、リン酸塩の中でも食品添加物に指定されているリン酸水素カリウム、具体的にはリン酸二水素カリウムを使用した。また、その二酸化チタン中の濃度は０．１〜１．０ｗｔ％の範囲にあればよいが、０．５〜０．９ｗｔ％の範囲にある方がよりいっそう好ましい。二酸化チタン中のリン酸二水素カリウムの濃度が０．１ｗｔ％以下では二酸化チタンが変色し、また１．０ｗｔ％以上の場合にはリン酸二水素カリウム自身が変色の原因となる。また、本実施の形態で使用したリン酸二水素カリウムの水溶液の濃度は、５〜１０ｗｔ％が好ましい。この範囲以下であると二酸化チタン粒子へのリン酸二水素カリウムの歩留まりが悪く、逆にこの範囲を超えると二酸化チタン粒子の凝集が起こる。本実施の形態では、二酸化チタンに対するリン酸二水素カリウムの濃度が０．１〜１．０ｗｔ％の含有率になるよう処理回数を調整した。
【０００８】
二酸化チタンをリン酸二水素カリウムで表面処理するには、攪拌槽の中で二酸化チタン粉を３００〜３５０℃まで加熱し、攪拌状態にある二酸化チタン粉にリン酸二水素カリウムの水溶液をスプレー処理する。３００〜３５０℃の温度域では、二酸化チタン粒子にスプレー処理されたリン酸二水素カリウム中の水分は短時間で揮発除去され、リン酸二水素カリウムのみが二酸化チタンの表面に吸着し、表面処理が完了する。
【０００９】
本実施の形態では、リン酸二水素カリウムを表面処理剤として使用したが、本発明の効果を得るには、これに限るものではなく、リン酸二水素ナトリウム、ピロリン酸カリウム、ピロリン酸ナトリウムあるいはピロリン酸水素ナトリウム、あるいは、ヘキサメタリン酸ナトリウム、ヘキサメタリン酸カリウム、あるいはまたポリリン酸のナトリウム塩やカリウム塩を使用してもよい。
二酸化チタンに前記のリン酸塩を表面処理するに際し、本実施の形態では攪拌槽を用いたが、二酸化チタンが十分に分散可能であれば、本装置に限るものではなく、例えば流動槽を用いてもよい。また、二酸化チタンの加熱温度は、特に制限はないが、水分の揮発除去性と経済性を考慮すると、１１０〜４００℃の範囲に設定する方が好ましい。
【００１０】
二酸化チタンに対するリン酸塩処理は、以上の方法で行ったが、二酸化チタンへのリン酸塩処理を水溶液中で行ってもよい。例えば二酸化チタンを分散させた水溶液中に、前記のリン酸塩水溶液あるいはリン酸塩自身を直接添加した後、乾燥することでも二酸化チタンへのリン酸塩処理を行うことができる。
【００１１】
（３）コーティング液の調整
コーティング液は、糖衣層用の白糖の水溶液に、上記のようにしてリン酸塩により表面処理された二酸化チタンを混合して得られる。白糖水溶液における白糖の濃度は５０〜８０ｗｔ％の範囲が好ましい。この範囲以下であると粘度が低くて中核錠への付着性が悪く、逆にこの範囲を超えると粘度が高まり中核錠への分散性が低下する。また、コーティング液がフィルム層用の場合、セルロース（例えばヒドロキシプロピルメチルセルロース）の水溶液に上記のリン酸塩処理した二酸化チタンを混合して得られる。セルロースの水溶液におけるセルロースの濃度は、中核錠への歩留まりと分散性の点で５〜２０ｗｔ％の範囲が好ましい。
上記コーティング液に、リン酸塩で表面処理された二酸化チタンを混合し、コーティング液とする。上記のリン酸塩処理した二酸化チタンの濃度は、１〜１０ｗｔ％の範囲が好ましく、中核錠の色調に応じて濃度を適宜に変更すればよい。
【００１２】
（４）コーティング層の形成
上記のようにして調整されたコーティング液を、中核錠の表面に吹き付けてコーティング層を形成する。本実施の形態においては、コーティング液を中核錠の表面にスプレー噴射して中核錠を被覆し、この後、１１０℃で大気乾燥することにより固化し、コーティング層を形成する。コーティング液のスプレー噴射と大気乾燥は、中核錠の固有の色に応じて適宜回数繰り返し行い、中核錠の色調を完全に隠蔽する。
【００１３】
このようにして得られた中核錠のコーティング層は、経時変化によっても変色せず、長期にわたって白色が保持される。
本発明の二酸化チタンは、薬剤を被覆するコーティング層のみならず、チョコレート等のタブレット状の食品のコーティング層などの着色剤としても使用可能である。
【００１４】
【実施例】
次に、本発明をより明らかにした実施例を説明する。
（１）糖衣層の実施例
［実施例１］
気相法で得られた平均粒径が０．２μｍの高純度二酸化チタン（東邦チタニウム社製）３００ｇを攪拌槽中において３５０℃に加熱しながら攪拌し、攪拌状態の該二酸化チタンに、リン酸二水素カリウム水溶液を一様にスプレー噴射して表面処理を施した。二酸化チタンの平均粒径は電子顕微鏡写真に基づいて測定した。リン酸二水素カリウム水溶液におけるリン酸二水素カリウムの濃度は、二酸化チタン１００ｇに対してリン酸二水素カリウムが０．５ｇの割合で添加され得る濃度とした。また、リン酸二水素カリウム水溶液の濃度は８ｗｔ％とした。
次に、このリン酸二水素カリウムで表面処理した二酸化チタンと６５ｗｔ％の白糖水溶液を、５０：１０００の重量割合で混合して糖衣液を製造した。続いて、この糖衣液を、表面が灰色の１０錠の薬剤にスプレーして平均厚さ０．５ｍｍの糖衣層をそれぞれ形成し、１０錠の糖衣錠を得た。
以上の工程を５回行って、１０錠ずつ５ロットの糖衣錠を製造し、ロットごとのサンプルＡ1 〜Ａ5 を得た。
【００１５】
［比較例１］
実施例１に対する比較例１として、二酸化チタンの表面処理を行わず、これ以外は上記実施例１と同様にして、糖衣錠のサンプルＢ1 〜Ｂ5 を製造した。
【００１６】
［実施例２］
気相法で得られた平均粒径が０．４μｍの高純度二酸化チタン（東邦チタニウム社製）５００ｇを攪拌槽に入れた２０００ｇの水中に分散させ、さらにピロリン酸ナトリウム３ｇを投入して攪拌混合した後、二酸化チタンを含む同水溶液を加熱して水分を揮発除去して表面処理を施した。次に、このピロリン酸ナトリウムで表面処理した二酸化チタンと６５ｗｔ％の白糖水溶液を、４０：１０００の重量割合で混合して糖衣液を製造した。続いて、この糖衣液を、表面が灰色の１０錠の薬剤にスプレーして平均厚さ０．５ｍｍの糖衣層をそれぞれ形成し、１０錠の糖衣錠を得た。
以上の工程を５回行って、１０錠ずつ５ロットの糖衣錠を製造し、ロットごとのサンプルＣ1 〜Ｃ5 を得た。
【００１７】
［比較例２］
実施例２に対する比較例２として、二酸化チタンの表面処理を行わず、これ以外は上記実施例２と同様にして、糖衣錠のサンプルＤ1 〜Ｄ5 を製造した。
【００１８】
（２）フィルム層の実施例
［実施例３］
上記実施例１の白糖に代えて１０ｗｔ％セルロース溶液を使用し、これ以外は実施例１と全く同一条件で薬剤にセルロース含有のフィルム層を形成し、１０錠のコーティング錠を得た。この工程を５回行って、１０錠ずつ５ロットのコーティング錠を製造し、ロットごとのサンプルＥ1 〜Ｅ5 を得た。
［比較例３］
実施例３に対する比較例３として、二酸化チタンの表面処理を行わず、これ以外は上記実施例３と同様にして、コーティング錠のサンプルＦ1 〜Ｆ5 を得た。
【００１９】
上記実施例１，２，３および比較例１，２，３の各サンプルを、出力２０Ｗの紫外線ランプの下に一週間連続して置く曝露試験を行い、変色の度合いを目視により調べ、実用に供することができるか否かの評価を行った。その結果を表１、表２および表３に示す。なお、変色の評価は次の通りである。
変色の評価 ◎：変色なし
○：変色が僅かに認められるが実用上問題ない
△：変色は軽度であるが実用上問題あり
×：変色が激しく実用上問題あり
【００２０】
【表１】
【表２】
【表３】
表１、表２および表３から明らかなように、二酸化チタンをリン酸塩により表面処理した実施例１，２，３の各サンプルについては、実用上問題がないことが確かめられた。一方、二酸化チタンをリン酸塩により表面処理しない比較例１，２の各サンプルは、いずれも実用上問題のあるレベルまで変色が生じており、リン酸塩による表面処理の効果が確かめられた。また、比較例３においては、実用上問題の生じないものもあったが、実施例３のように二酸化チタンをリン酸塩により表面処理した方が明らかに耐変色性に優れることが判った。
【００２４】
【発明の効果】
以上説明したように、本発明の二酸化チタンを白色着色剤としてコーティング層を形成することにより、経時変化によるコーティング層の変色が長期にわたって防止され、コーティング錠としての商品価値が維持される。[0001]
[Industrial application fields]
The present invention relates to titanium dioxide having a white coating layer covering the surface of a tablet-like drug or food, and more particularly to an improvement in which whitening is prolonged by improving discoloration resistance.
[0002]
[Prior art]
For example, drugs in the form of tablets are often tablets in which a core tablet is coated with a coating layer in order to conceal the bitterness and color of the drug itself and make it easier to take. Such a coating layer is generally obtained by solidifying a coating liquid mainly composed of sugar or cellulose, a binder, and water. In the following description, the coating layer when specified as containing sugar or sucrose is referred to as a sugar coating layer, and the coating layer specified as containing cellulose is referred to as a film layer. The binder enhances the binding force with the core tablet, which is a drug or food material, and gelatin, agar, gum arabic, or the like is used as disclosed in JP-A-9-25245. The coating layer is colored in various colors according to the purpose of use, and a colorant is also added for that purpose. In particular, in the case of a drug, the white color is many, and as a colorant that makes the coating layer white, as disclosed in JP-A-9-25245, potato, corn, wheat starch, starch such as rice, calcium carbonate, There are talc and titanium dioxide. Among these, titanium dioxide, which is an inorganic white pigment, is excellent in optical properties such as whiteness, hiding power, and coloring power. This titanium dioxide is roughly classified into a rutile type and an anatase type due to the difference in crystal structure. In particular, rutile type titanium dioxide is widely used as a colorant for a coating layer for drugs because of its high weather resistance.
[0003]
[Problems to be solved by the invention]
However, according to the present inventor, a coating liquid prepared by mixing sucrose or cellulose and titanium dioxide in water is coated on a core tablet such as a drug to form a coated tablet, and the coated tablet is left under natural light or ultraviolet light. As a result, it has been confirmed that there are those whose surface changes to blue-gray due to a change with time (hereinafter, the change to blue-gray is simply referred to as discoloration). This discoloration is presumed to be because the ultraviolet rays contained in the natural light were irradiated on the titanium dioxide, oxygen was desorbed from the titanium dioxide, and a part of the titanium dioxide in the coating layer was changed to a suboxide. That is, it has been found that even when titanium dioxide having excellent optical properties is used as a colorant for the coating layer, discoloration may occur over time, leading to a reduction in commercial value.
Therefore, an object of the present invention is to provide a titanium dioxide for coating which can keep a white color over a long period of time without causing the coating layer to change color with time.
[0004]
[Means for Solving the Problems]
As described above, based on the assumption that the discoloration of the coating layer is caused by the photocatalytic action of titanium dioxide, the inventors have conducted extensive research on means for suppressing the photocatalytic action, and as a result, the phosphate treatment When a coating layer was formed with a coating solution containing added titanium dioxide, it was found that no discoloration occurred even when left under natural light or ultraviolet light.
The present invention has been made on the basis of such findings, and is a coating titanium dioxide forming a core tablet coating layer, which is treated with potassium dihydrogen phosphate or sodium pyrophosphate , and diphosphate phosphate in the coating. The concentration of potassium hydrogen or sodium pyrophosphate is 0.1 to 1.0 wt% .
[0005]
Since the concentration of the phosphate is related to discoloration, appropriate regulation is necessary, and a concentration of 0.1 to 1.0 wt% is preferable, and 0.5 to 0.9 wt% is more preferable. Below this range, the titanium dioxide changes color, and above this range, the phosphate itself may cause discoloration.
In addition, the titanium dioxide used is in the form of fine powder, and is required to have pigment properties such as dispersion and mixing in the coating liquid, coloring power, hiding power, and even when actually touching the mouth. In consideration of not feeling uncomfortable when swallowing, it is preferable that the particle size is about 0.1 to 0.8 μm, and more preferably 0.2 to 0.4 μm.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, more preferred embodiments of the present invention will be described.
(1) Since titanium dioxide constituting the titanium dioxide coating layer is taken into the body, high-purity titanium dioxide that satisfies the regulations of the Japanese Pharmacopoeia is required. Also in the present invention, high-purity titanium dioxide powder (manufactured by Toho Titanium Co., Ltd.) that satisfies Japanese Pharmacopoeia standards was used. Moreover, the preferable average particle diameter of titanium dioxide is 0.2 to 0.4 μm, and sufficient dispersibility / mixability in the coating solution, as well as discomfort when touching or swallowing when actually swallowed in the mouth. A level that satisfies what you do not remember is secured. The particle size was measured based on an electron micrograph.
[0007]
(2) Surface treatment of titanium dioxide with phosphate and phosphate For surface treatment of titanium dioxide, in this embodiment, potassium hydrogen phosphate designated as a food additive among phosphates, specifically For this, potassium dihydrogen phosphate was used. Further, the concentration in titanium dioxide may be in the range of 0.1 to 1.0 wt%, but it is more preferable to be in the range of 0.5 to 0.9 wt%. When the concentration of potassium dihydrogen phosphate in the titanium dioxide is 0.1 wt% or less, the titanium dioxide is discolored, and when it is 1.0 wt% or more, the potassium dihydrogen phosphate itself causes discoloration. The concentration of the aqueous solution of potassium dihydrogen phosphate used in the present embodiment is preferably 5 to 10 wt%. If it is below this range, the yield of potassium dihydrogen phosphate on the titanium dioxide particles is poor, and conversely if it exceeds this range, aggregation of the titanium dioxide particles occurs. In this Embodiment, the frequency | count of a process was adjusted so that the density | concentration of the potassium dihydrogen phosphate with respect to titanium dioxide might become a content rate of 0.1-1.0 wt%.
[0008]
To surface-treat titanium dioxide with potassium dihydrogen phosphate, heat the titanium dioxide powder to 300-350 ° C in a stirring tank and spray the aqueous solution of potassium dihydrogen phosphate onto the titanium dioxide powder in the stirring state. To do. In the temperature range of 300 to 350 ° C., water in potassium dihydrogen phosphate sprayed onto titanium dioxide particles is volatilized and removed in a short time, and only potassium dihydrogen phosphate is adsorbed on the surface of titanium dioxide, surface treatment. Is completed.
[0009]
In this embodiment, potassium dihydrogen phosphate is used as a surface treatment agent. However, in order to obtain the effects of the present invention, the present invention is not limited to this. Sodium dihydrogen phosphate, potassium pyrophosphate, sodium pyrophosphate or Sodium hydrogen pyrophosphate, sodium hexametaphosphate, potassium hexametaphosphate, or sodium salt or potassium salt of polyphosphoric acid may be used.
In the present embodiment, a stirring tank was used in the surface treatment of the above phosphate to titanium dioxide. However, the titanium dioxide is not limited to this apparatus as long as titanium dioxide can be sufficiently dispersed. For example, a fluidized tank is used. May be. In addition, the heating temperature of titanium dioxide is not particularly limited, but it is preferable to set the temperature within a range of 110 to 400 ° C. in consideration of water volatilization removability and economy.
[0010]
Although the phosphate treatment for titanium dioxide was performed by the above method, the phosphate treatment for titanium dioxide may be performed in an aqueous solution. For example, the phosphate treatment of titanium dioxide can be performed by directly adding the above-mentioned phosphate aqueous solution or phosphate itself to an aqueous solution in which titanium dioxide is dispersed, and then drying.
[0011]
(3) Preparation of coating liquid A coating liquid is obtained by mixing titanium dioxide surface-treated with a phosphate as described above into an aqueous solution of white sugar for a sugar coating layer. The sucrose concentration in the sucrose aqueous solution is preferably in the range of 50 to 80 wt%. If it is below this range, the viscosity is low and the adhesion to the core tablet is poor, and conversely if it exceeds this range, the viscosity increases and the dispersibility to the core tablet decreases. Moreover, when a coating liquid is for film layers, it is obtained by mixing the above-mentioned phosphate-treated titanium dioxide with an aqueous solution of cellulose (for example, hydroxypropylmethylcellulose). The concentration of cellulose in the aqueous cellulose solution is preferably in the range of 5 to 20 wt% in terms of yield and dispersibility in the core tablet.
Titanium dioxide surface-treated with phosphate is mixed with the coating solution to obtain a coating solution. The concentration of the above-mentioned phosphate-treated titanium dioxide is preferably in the range of 1 to 10 wt%, and the concentration may be appropriately changed according to the color tone of the core tablet.
[0012]
(4) Formation of coating layer The coating liquid prepared as described above is sprayed onto the surface of the core tablet to form a coating layer. In the present embodiment, the coating liquid is sprayed onto the surface of the core tablet to coat the core tablet, and then solidified by air drying at 110 ° C. to form a coating layer. The spraying of the coating liquid and air drying are repeated as many times as necessary according to the unique color of the core tablet, thereby completely hiding the color tone of the core tablet.
[0013]
The coating layer of the core tablet thus obtained does not change color even with aging and remains white for a long time.
The titanium dioxide of the present invention can be used not only as a coating layer for coating a drug but also as a colorant for a coating layer of a tablet-like food such as chocolate.
[0014]
【Example】
Next, an embodiment in which the present invention is clarified will be described.
(1) Examples of sugar coating layers [Example 1]
300 g of high-purity titanium dioxide (manufactured by Toho Titanium Co., Ltd.) having an average particle size of 0.2 μm obtained by the vapor phase method was stirred while being heated to 350 ° C. in a stirring vessel, and phosphoric acid was added to the stirred titanium dioxide. Surface treatment was performed by spraying a potassium dihydrogen aqueous solution uniformly. The average particle diameter of titanium dioxide was measured based on an electron micrograph. The concentration of potassium dihydrogen phosphate in the aqueous potassium dihydrogen phosphate solution was such that potassium dihydrogen phosphate could be added at a ratio of 0.5 g to 100 g of titanium dioxide. The concentration of the potassium dihydrogen phosphate aqueous solution was 8 wt%.
Next, the titanium dioxide surface-treated with this potassium dihydrogen phosphate and a 65 wt% sucrose aqueous solution were mixed at a weight ratio of 50: 1000 to produce a sugar coating liquid. Subsequently, the sugar-coating liquid was sprayed on 10 tablets with a gray surface to form a sugar-coating layer with an average thickness of 0.5 mm to obtain 10 sugar-coated tablets.
The above process was performed 5 times to produce 5 lots of sugar-coated tablets of 10 tablets, and samples A 1 to A 5 for each lot were obtained.
[0015]
[Comparative Example 1]
As Comparative Example 1 with respect to Example 1, the surface treatment of titanium dioxide was not performed, and samples B 1 to B 5 of sugar-coated tablets were produced in the same manner as in Example 1 except for this.
[0016]
[Example 2]
500 g of high-purity titanium dioxide (manufactured by Toho Titanium Co., Ltd.) having an average particle size of 0.4 μm obtained by the vapor phase method is dispersed in 2000 g of water in a stirring tank, and 3 g of sodium pyrophosphate is further added and stirred. After that, the aqueous solution containing titanium dioxide was heated to volatilize and remove moisture, and surface treatment was performed. Next, the titanium dioxide surface-treated with sodium pyrophosphate and a 65 wt% sucrose aqueous solution were mixed at a weight ratio of 40: 1000 to produce a sugar coating liquid. Subsequently, the sugar-coating liquid was sprayed on 10 tablets with a gray surface to form a sugar-coating layer with an average thickness of 0.5 mm to obtain 10 sugar-coated tablets.
The above process was repeated 5 times to produce 5 lots of sugar-coated tablets of 10 tablets, and samples C 1 to C 5 for each lot were obtained.
[0017]
[Comparative Example 2]
Comparative Example 2 for Example 2, without performing the surface treatment of titanium dioxide, other in the same manner as in Example 2 was used to prepare the samples D 1 to D 5 dragees.
[0018]
(2) Example of film layer [Example 3]
A 10 wt% cellulose solution was used in place of the sucrose of Example 1, and a cellulose-containing film layer was formed on the drug under exactly the same conditions as in Example 1 to obtain 10 coated tablets. This process was repeated 5 times to produce 5 lots of coated tablets of 10 tablets, and samples E 1 to E 5 for each lot were obtained.
[Comparative Example 3]
As Comparative Example 3 with respect to Example 3, the surface treatment of titanium dioxide was not performed, and the samples F 1 to F 5 of coated tablets were obtained in the same manner as in Example 3 except that.
[0019]
An exposure test was conducted in which the samples of Examples 1, 2, 3 and Comparative Examples 1, 2, 3 were placed under an ultraviolet lamp with an output of 20 W for one week continuously, and the degree of discoloration was visually examined to make it practical. An evaluation was made as to whether or not it could be provided. The results are shown in Table 1, Table 2 and Table 3. In addition, the evaluation of discoloration is as follows.
Evaluation of discoloration ◎: No discoloration ○: Slight discoloration is observed but no problem for practical use Δ: Discoloration is mild but practically problematic ×: Discoloration is severe and practically problematic [0020]
[Table 1]
[Table 2]
[Table 3]
As is clear from Tables 1, 2 and 3, it was confirmed that there was no practical problem with respect to the samples of Examples 1, 2 and 3 in which titanium dioxide was surface-treated with phosphate. On the other hand, each sample of Comparative Examples 1 and 2 in which titanium dioxide was not surface-treated with phosphate was discolored to a level that had a practical problem, and the effect of surface treatment with phosphate was confirmed. Further, in Comparative Example 3, although there were some which did not cause a problem in practice, it was found that the surface treatment of titanium dioxide with phosphate as in Example 3 was clearly superior in discoloration resistance.
[0024]
【The invention's effect】
As described above, by forming a coating layer using the titanium dioxide of the present invention as a white colorant, discoloration of the coating layer due to aging is prevented over a long period of time, and the commercial value as a coated tablet is maintained.
Claims (12)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03678598A JP4187299B2 (en) | 1998-02-03 | 1998-02-03 | Titanium dioxide for coating and production method thereof, coating liquid for forming titanium dioxide coating, coating agent and food |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03678598A JP4187299B2 (en) | 1998-02-03 | 1998-02-03 | Titanium dioxide for coating and production method thereof, coating liquid for forming titanium dioxide coating, coating agent and food |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11222442A JPH11222442A (en) | 1999-08-17 |
| JP4187299B2 true JP4187299B2 (en) | 2008-11-26 |
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| JP03678598A Expired - Lifetime JP4187299B2 (en) | 1998-02-03 | 1998-02-03 | Titanium dioxide for coating and production method thereof, coating liquid for forming titanium dioxide coating, coating agent and food |
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| CN103096888B (en) * | 2011-08-08 | 2014-08-27 | 株式会社三和化学研究所 | Coated preparation containing azosemide as active ingredient |
| CN113933128A (en) * | 2021-11-26 | 2022-01-14 | 攀钢集团重庆钛业有限公司 | Method for detecting whiteness of titanium dioxide in paint |
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