JP4111701B2

JP4111701B2 - Modified titanium oxide particles

Info

Publication number: JP4111701B2
Application number: JP2001304959A
Authority: JP
Inventors: 義憲若宮; 広泰西田; 嗣雄小柳; 通郎小松
Original assignee: 触媒化成工業株式会社
Priority date: 2001-10-01
Filing date: 2001-10-01
Publication date: 2008-07-02
Anticipated expiration: 2021-10-01
Also published as: JP2003112923A

Description

【０００１】
【発明の技術分野】
本発明は、塗料、光学材料、化粧用材料などの用途に有用な新規な酸化チタン粒子に関する。
【０００２】
【発明の技術的背景】
酸化チタン粒子は、その化学的、物理的特性を利用した用途が広く、白色顔料、酸化還元触媒あるいは触媒担体として、また紫外線の遮蔽力・隠蔽力を利用した化粧料、プラスチックの表面コート剤として、さらには高屈折を利用した反射防止コート材、導電性を利用した帯電防止材等として用いられたり、これらの効果を組み合わせて機能性ハードコート材に用いられたり、さらに高いバンドギャップに基づく光触媒機能、防菌剤、防汚剤、超親水性被膜、太陽電池などに用いられている。
このような酸化チタン粒子としては、通常ルチル型の酸化チタン粒子、アナターゼ型の酸化チタン粒子、ブルッカイト型の酸化チタン粒子およびこれら結晶性酸化チタンを修飾した酸化チタン粒子が用いられているが、塗料、化粧料、ハードコート材料等にこれらの酸化チタンを用いる場合、特に油脂や有機樹脂等の有機物と組み合わせて用いる場合には、酸化チタンが紫外線を吸収して活性化し、有機物の酸化を惹起して耐候性、耐光性、耐久性等を低下させることがあり、塗料が変色したり、樹脂レンズ基材が劣化する等の問題が指摘されている。
【０００３】
特開平２−２６４９０９号公報、特開平３−６８９０１号公報、特開平５−２１０２号公報には、酸化チタンにＣｅＯ₂あるいはＦｅ₂Ｏ₃を複合化した粒子を用いることにより耐候性が増し、基材樹脂レンズの劣化が抑制されることが開示されている。
また、本願出願人は、特開平８−４８９４０号公報にて、高屈折率プラスチックレンズの表面コート膜に、酸化チタンとＺｒＯ₂、Ａｌ₂Ｏ₃、ＳｉＯ₂等を複合化した粒子を用いることにより耐光性が増し、基材樹脂レンズの劣化が抑制されることを開示している。しかしながら、耐候性が改善したものの、いまだ不十分であり、長期間の使用により変色したり着色する問題があった。
【０００４】
塗料等に顔料として用いる場合についても、酸化チタン基体粒子をスズの水和酸化物およびジルコニウムの水和酸化物で被覆し、さらにアルミニウムの水和酸化物で被覆した二酸化チタン顔料が開示されている（特開昭５７−０８５８５９号公報）。
また、中核酸化チタン粒子をスズの含水酸化物およびジルコニウムの含水酸化物で被覆し、ついでチタンの含水酸化物で被覆し、さらにアルミニウムの含水酸化物で被覆した二酸化チタン顔料が開示されている（特開昭６１−２８１０１８号公報）。
さらに、特開平６−４９３８７号公報、特開平７−２９２２７７号公報には酸化ランタンで被覆したり、シリカ、酸化錫、酸化ジルコニウム、アルミナで被覆することが開示されている。
【０００５】
しかしながら、これらも耐候性が向上したものの、いまだ不十分であり、長期間の使用により変色したり着色する問題があった。このためさらに酸化チタンの活性を抑制することが求められており、用途によっては実質的に不活性にすることが求められている。
このような状況のもと、本発明者らは、さらに鋭意研究を重ねた結果、酸化チタン粒子の表面をシリカ系複合酸化物と例えばアルカリ土類金属酸化物とからなる酸化物で被覆することにより酸化チタンの活性を抑制できることを見出して本発明を完成した。
【０００６】
【発明の目的】
本発明は、実質的に不活性で、塗料、化粧料、ハードコート材等として好適に用いることのできる、表面がシリカ系複合酸化物と他の無機酸化物からなる被覆層で被覆された改質酸化チタン粒子を提供することを目的としている。
【０００７】
【発明の概要】
本発明は、シリカ系複合酸化物（Ａ）と無機酸化物（Ｂ）からなる被覆層で表面が被覆された酸化チタン粒子であって、シリカ系複合酸化物（Ａ）が下記式（１）で表される元素Ｍと珪素の複合酸化物であり、無機酸化物（Ｂ）がＣｕ、Ａｇ、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｚｎ、Ｌａ、Ｃｅ、Ａｌ、Ｚｒ、Ｐｂ、Ｓｎ、Ｎｂ、Ｔａ、Ｓｂ、Ｍｏ、Ｆｅ、およびＮｉからなる元素群から選ばれたＭ以外の元素の酸化物の１種または２種以上であることを特徴とするものである。
ＳｉＯ₂・ｎＭ_2/VＯ・・・（１）
（但し、Ｍ：Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ａｌ、Ｔｉ、Ｚｒ、Ｓｂ、またはＭｏであり、Ｖ：元素Ｍの原子価であり、ｎ：０. １〜１である。）
前記シリカ系複合酸化物（Ａ）の含有量が１〜４５重量％の範囲にあり、前記無機酸化物（Ｂ）の含有量が０. １〜１０重量％の範囲にあることが好ましい。前記シリカ系複合酸化物（Ａ）を構成する元素Ｍは、ＡｌまたはＺｒのいずれかであることが好ましい。
前記無機酸化物（Ｂ）を構成する元素は、Ｍｇ、Ｃａ、Ｓｒ、Ｂａから選ばれる１種または２種以上であることが好ましい。
前記無機酸化物（Ｂ）を構成する元素は、Ｂａ、Ｌａ、Ｓｎから選ばれる１種または２種以上であることが好ましい。
前記被覆層が、シリカ系複合酸化物（Ａ）の層に無機酸化物（Ｂ）が分散した複合化被覆層であることが好ましい。
特に、無機酸化物（Ｂ）を構成する金属元素のカチオンがイオン交換によりシリカ系複合酸化物（Ａ）の層に分散してなることが好ましい。
【０００８】
【発明の具体的な説明】
以下、本発明に係る改質酸化チタン粒子について具体的に説明する。
酸化チタン粒子
本発明に用られる酸化チタン粒子としては、塗料、化粧料、ハードコート材等に顔料、紫外線吸収剤、高屈折率材料等として用いられる従来公知の酸化チタン粒子が挙げられる。酸化チタン粒子の結晶形に関するアナターゼ型、ルチル型、ブルッカイト型、無定型などの制約は特にないが、ルチル型酸化チタンはアナターゼ型のものに比べて屈折率が高く活性が低いので好適である。また、粒子の大きさ、形状等についての特別の制限もないが、通常５ｎｍ〜１０μｍのものが用いられる。
【０００９】
シリカ系複合酸化物（Ａ）
被覆層を構成するシリカ系複合酸化物（Ａ）は、シリカを主成分とし、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ａｌ、Ｔｉ、Ｚｒ、Ｓｂ、およびＭｏの中から選ばれるいずれかの元素の酸化物とからなる複合酸化物である。このようなシリカを主成分とする複合酸化物は酸化チタン粒子を緻密に被覆することができ、かつこれら複合酸化物はシリカの珪素原子の一部が前記元素で置換された構造を有し、このため多くの場合、シリカの酸素原子に配位された置換原子部分は負電荷となり、この負電荷を中和する形でカチオンが配位できるようになる。このときのカチオンとしては、複合酸化物層を形成する過程で存在するカチオン、例えばＮａ⁺等が存在する。このようなカチオンの存在により、後述する無機酸化物（Ｂ）を構成する元素のカチオンをイオン交換する形で複合酸化物層に付着、担持させることができ、本発明の被覆層が形成される。
従って、シリカ系複合酸化物（Ａ）を構成するシリカ以外の成分としては、シリカの珪素原子と置換可能な元素であればよいが、置換がより多くできる元素（Ｍ）として前記Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ａｌ、Ｔｉ、Ｚｒ、Ｓｂ、およびＭｏが挙げられ、特に、Ａｌ、Ｔｉ、Ｚｒ、およびＭｇが好ましい。
【００１０】
このようなシリカ系複合酸化物（Ａ）中のシリカ以外の成分の含有量は前記式（１）に置いてｎが０. １〜１. ０、好ましくは０. １５〜０. ８５、より好ましくは０. ２〜０. ５の範囲である。ｎが０. １未満の場合は、シリカ以外の成分の格子置換が少なく、後述する無機酸化物（Ｂ）を構成する元素のカチオンの付着量が少なくなり、酸化チタンの活性の抑制が不充分となる。一方、ｎが１.０を越えても、シリカ以外の成分の格子置換がさらに増加することはなく、無機酸化物（Ｂ）構成する元素のカチオンの付着量は減少するようになったり、また、シリカ以外の成分の種類にもよるが緻密なシリカ系複合酸化物（Ａ）層が形成できない場合があり、このため酸化チタンの活性の抑制が不充分となる。
【００１１】
無機酸化物（Ｂ）
被覆層を構成する無機酸化物（Ｂ）は、Ｃｕ、Ａｇ、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｚｎ、Ｌａ、Ｃｅ、Ａｌ、Ｚｒ、Ｐｂ、Ｓｎ、Ｎｂ、Ｔａ、Ｓｂ、Ｍｏ、Ｆｅ、Ｎｉからなる元素群（Ｅ）から選ばれる１種または２種以上の元素の酸化物からなり、前記シリカ系複合酸化物（Ａ）の層に前記元素のカチオンが付着（以下、イオン交換ということがある）して構成されている。即ち、無機酸化物（Ｂ）は、シリカ系複合酸化物（Ａ）に均一に分散し、シリカ系複合酸化物（Ａ）と複合化した被覆層を構成しているものと考えられる。
上記シリカ系複合酸化物（Ａ）に無機酸化物（Ｂ）を導入した複合被覆層が酸化チタンの活性を抑制することができる原因については必ずしも明らかではないが、次のような理由が考えられる。
▲１▼被覆層が太陽光等の光を遮蔽する。
▲２▼無機酸化物（Ｂ）を構成するイオンが、酸化チタン粒子内で生成する電子（ｅ^-）または正孔（ｈ⁺）の生成を抑制するか電気的に中和して消滅させる。
▲３▼前記▲１▼および／または▲２▼に加えて、被覆層により有機物等と隔絶される。
前記元素群（Ｅ）の中では、Ｍｇ、Ｃａ、Ｓｒ、およびＢａが好ましく、この種のアルカリ土類金属を用いると酸化チタンの活性をより効果的に抑制することができる。
【００１２】
次に、改質酸化チタン粒子中のシリカ系複合酸化物（Ａ）の含有量は１〜４５重量％、さらには５〜３０重量％の範囲にあることが好ましい。この含有量が１重量％未満の場合は、酸化チタン粒子の表面の全面を被覆できないことがあり、できたとしても、無機酸化物（Ｂ）の導入量が不充分となり、酸化チタンの活性を抑制する効果が充分得られないことがある。含有量が４５重量％を越えると、酸化チタンの含有量が低下し、高屈折率、白色酸化チタン顔料など酸化チタン独自の特性が低下し、酸化チタンの使用目的を充分達成することができない場合がある。
また、改質酸化チタン粒子中の無機酸化物（Ｂ）の含有量は、０. １〜１０重量％、さらには１〜５重量％の範囲にあることが好ましい。この含有量が０. １重量％未満の場合は酸化チタンの活性を抑制する効果が充分得られないことがある。他方、含有量が１０重量％を越えて導入することは困難であり、できたとしても酸化チタンの活性を抑制する効果がさらに増すこともない。
【００１３】
改質酸化チタン粒子の製造方法
続いて、前記改質酸化チタン粒子の製造方法を説明する。
〔シリカ系複合酸化物層の形成〕
先ず、前述した酸化チタン粒子を水に分散させて酸化チタンの水分散液を調製する。分散液の酸化チタン粒子濃度はＴｉＯ₂として０. １〜１０重量％、特に０. ２〜５重量％の範囲にあることが好ましい。酸化チタン粒子の濃度が０. １重量％未満の場合は、濃度が低すぎて、次工程におけるシリカ系複合酸化物前駆体の酸化チタン粒子表面上への析出が効率的に起きず、また後工程で濃縮する際の効率も悪い。酸化チタン粒子の濃度が１０重量％を越えると、濃度が高すぎて酸化チタン粒子が凝集することがあるので好ましくない。
【００１４】
次に、分散液にアルカリを加えて分散液のｐＨを９〜１２、特に９. ５〜１１. ５の範囲に調整する。アルカリとしては、ＮａＯＨ、ＫＯＨなどのアルカリ金属水酸化物の他、アンモニア、４級アミン等の塩基性窒素化合物を用いることができる。分散液のｐＨが上記範囲にあると、緻密なシリカ系複合酸化物による被覆が得られ、酸化チタンと有機物の接触が効果的に遮断されるので、酸化チタンの活性を抑制することができる。
ついで、分散液にシリカ源としてアルカリ金属珪酸塩水溶液と、前記元素（Ｍ）の可溶性金属塩水溶液とを、同時に、連続的にまたは断続的に添加してシリカ系複合酸化物の前駆体水和物を酸化チタン粒子表面上に析出させる。
前記アルカリ金属珪酸塩としては珪酸ナトリウム、珪酸カリウムなどが用いられ、元素（Ｍ）の可溶性金属塩としては塩化マグネシウム、アルミン酸ナトリウム、塩化チタン、塩化ジルコニウム、塩化アンチモン、硫酸モリブデンなどが挙げられる。
【００１５】
このとき分散液の温度は通常５０〜１００℃、さらには６５℃〜９５℃の範囲とすることが好ましく、アルカリ金属珪酸塩と元素（Ｍ）の可溶性金属塩の添加量比は、前記式（１）において所定のモル比ｎとなるようにする。
両水溶液の添加速度は、分散液の温度やシリカ系複合酸化物を含む被覆層の形成割合等によって適宜選択することができ、分散液がゲル化したりあるいは酸化チタン粒子が凝集することのない範囲でゆっくり添加し、酸化チタン粒子表面上に選択的にシリカ系複合酸化物前駆体を析出させることが重要である。
前記水溶液の添加終了後、さらに緻密なシリカ系複合酸化物層を形成し、酸化チタンの活性抑制効果を向上させるために、前記分散液を熟成することが好ましい。熟成は、前記水溶液の添加時の温度より高くすることが可能であり、例えば１５０℃程度のオートクレーブ中で、概ね１０分から２時間の範囲で行うことができる。
次に、分散液を洗浄し、必要に応じて濃縮し、ついで５０〜１５０℃の範囲で乾燥してシリカ系複合酸化物層を形成した酸化チタン粒子を得る。洗浄方法は、ｐＨ調整剤や原料に由来するカチオンおよびアニオンを除去することができれば特に制限はなく、例えば、限外濾過膜法、イオン交換樹脂法、イオン交換膜、脱水濾過洗浄法などが好適である。
【００１６】
〔無機酸化物（Ｂ）成分の導入〕
上記で得たシリカ系複合酸化物層が形成された酸化チタン粒子の水分散液を調製する。このときの酸化チタン粒子の濃度は酸化物として０. １〜３０重量％、特に１〜２０重量％の範囲にあることが好ましい。酸化チタン粒子の濃度が０.１重量％未満の場合は、濃度が低すぎて生産効率が低く、酸化チタン粒子の濃度が３０重量％を越えると、濃度が高すぎて酸化チタン粒子が均一に分散できないことがあり、無機酸化物（Ｂ）成分前駆体の導入が不均一になる傾向がある。
ついで、元素群（Ｅ）中の金属塩（塩酸塩、硫酸塩、硝酸塩等）であって前記シリカ系複合酸化物（Ａ）の形成に用いた可溶性金属塩を除く金属塩水溶液を添加し、通常３０〜９５℃の温度範囲で、１分〜６０分程度撹拌する。このとき前述したように、金属塩の金属カチオンが主にイオン交換によりシリカ系複合酸化物に均一に担持される。
【００１７】
【発明の効果】
本発明の酸化チタン粒子は、シリカ系複合酸化物（Ａ）と特定の元素の無機酸化物（Ｂ）からなる被覆層で被覆されているために酸化チタンとしての高い屈折率や紫外線遮蔽性・隠蔽性を有していながら、その活性が効果的に抑制されている。従って、この改質酸化チタン粒子は、耐光性・耐候性等に優れた塗料、化粧料、ハードコート材、合成樹脂レンズ等に好適に用いることができる。
【００１８】
【実施例】
以下、実施例により説明するが、本発明はこれらの実施例により限定されるものではない。
〔実施例１〕
酸化チタン粒子（TITANIX 社製：CR-90 、ルチル型酸化チタン、平均粒子径０. ２５μｍ）２０ｇを純水３. ９８ｋｇに均一に分散させ、分散液に濃度２０重量％のＮａＯＨ水溶液５ｇを加えて分散液のｐＨを１０. ５とした。ついで、分散液の温度を９０℃に昇温し、３０分間撹拌した後、ＳｉＯ₂としての濃度が１. ５重量％の希釈３号水硝子３００ｇとＡｌ₂Ｏ₃としての濃度が０. ５重量％のアルミン酸ソーダ３００ｇとを同時に、連続的に４. ５時間で添加した。ついで、１時間熟成した後、常温に冷却し、限外濾過膜法で洗浄と濃縮を行い酸化物としての濃度が２０重量％のＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子分散液を得た。この分散液を１５０℃で乾燥してＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子２４ｇを得た。
【００１９】
得られたＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子３. ０８ｇを純水５８. ５２ｇに均一に分散させ、これに濃度１０重量％のＢａＣｌ₂水溶液３. ０ｇを加え、３０℃で１時間撹拌した後、限外濾過膜法で流出液の電導度が５０μＳ／ｃｍ以下となるまで洗浄し、ついで酸化物として濃度２０重量％に濃縮した。ついで、１５０℃で乾燥してＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子にＢａＯを担持した改質酸化チタン粒子（Ａ）２. ６ｇを得た。得られた粒子の組成を表１に示す。
また、酸化チタン粒子の活性としての耐ＵＶ性を評価し、その結果を表１に示した。耐ＵＶ性の測定は、改質酸化チタン粒子（Ａ）１ｇとアクリル樹脂３ｇとをメノウ乳鉢で混合し、これをルツボに採取し高圧水銀ランプ（ＨＢ−１０００−Ａ）により紫外線を照射し、樹脂が着色するまでの時間を測定した。
【００２０】
〔実施例２〕
酸化チタン粒子（TITANIX 社製：CR-90 、ルチル型酸化チタン、平均粒子径０. ２５μｍ）１８. ８ｇを純水３. ９８ｋｇに均一に分散させ、分散液に濃度２０重量％のＮａＯＨ水溶液４. ７ｇを加えて分散液のｐＨを１０. ５とした。ついで、分散液の温度を９０℃に昇温し、３０分間撹拌した後、ＳｉＯ₂としての濃度が１. ５重量％の希釈３号水硝子１５０ｇとＡｌ₂Ｏ₃としての濃度が０.５重量％のアルミン酸ソーダ１５０ｇとを同時に、連続的に３時間で添加した。ついで、１時間熟成した後、常温に冷却し、限外濾過膜法で洗浄と濃縮を行い酸化物としての濃度が２０重量％のＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子分散液を得た。この分散液を１５０℃で乾燥してＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子１９. ４ｇを得た。
得られたＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子２. ４９ｇを純水５８. ５２ｇに均一に分散させ、これに濃度１０重量％のＢａＣｌ₂水溶液１２. １ｇを加え、３０℃で１時間撹拌した後、限外濾過膜法で流出液の電導度が５０μＳ／ｃｍ以下となるまで洗浄し、ついで酸化物として濃度２０重量％に濃縮した。ついで、１５０℃で乾燥してＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子にＢａＯを担持した改質酸化チタン粒子（Ｂ）２. ６ｇを得た。得られた粒子の組成を表１に示し、また耐ＵＶ性を評価し、結果を表１に示した。
【００２１】
〔実施例３〕
酸化チタン粒子（TITANIX 社製：CR-90 、ルチル型酸化チタン、平均粒子径０. ２５μｍ）１７. ４ｇを純水３. ９８ｋｇに均一に分散させ、分散液に濃度２０重量％のＮａＯＨ水溶液４. ３５ｇを加えて分散液のｐＨを１０. ５とした。ついで、分散液の温度を９０℃に昇温し、３０分間撹拌した後、ＳｉＯ₂としての濃度が１. ５重量％の希釈３号水硝子３００ｇとＡｌ₂Ｏ₃としての濃度が０. ５重量％のアルミン酸ソーダ３００ｇとを同時に、連続的に４. ５時間で添加した。ついで、１時間熟成した後、常温に冷却し、限外濾過膜法で洗浄と濃縮を行い酸化物としての濃度が２０重量％のＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子分散液を得た。この分散液を１５０℃で乾燥してＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子２１. ８ｇを得た。
得られたＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子２. ８ｇを純水５８. ５２ｇに均一に分散させ、これに濃度１０重量％のＢａＣｌ₂水溶液２７. ３ｇを加え、３０℃で１時間撹拌した後、限外濾過膜法で流出液の電導度が５０μＳ／ｃｍ以下となるまで洗浄し、ついで酸化物として濃度２０重量％に濃縮した。ついで、１５０℃で乾燥してＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子にＢａＯを担持した改質酸化チタン粒子（Ｃ）３. １ｇを得た。得られた粒子の組成を表１に示し、また耐ＵＶ性を評価し、結果を表１に示した。
【００２２】
〔実施例４〕
酸化チタン粒子（TITANIX 社製：CR-90 、ルチル型酸化チタン、平均粒子径０. ２５μｍ）２４. ６ｇを純水３. ９８ｋｇに均一に分散させ、分散液に濃度２０重量％のＮａＯＨ水溶液６. １６ｇを加えて分散液のｐＨを１０. ５とした。ついで、分散液の温度を９０℃に昇温し、３０分間撹拌した後、ＳｉＯ₂としての濃度が１. ５重量％の希釈３号水硝子１００ｇとＡｌ₂Ｏ₃としての濃度が０. ５重量％のアルミン酸ソーダ１００ｇとを同時に、連続的に１. ５時間で添加した。ついで、１時間熟成した後、常温に冷却し、限外濾過膜法で洗浄と濃縮を行い酸化物としての濃度が２０重量％のＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子分散液を得た。この分散液を１５０℃で乾燥してＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子２３ｇを得た。
得られたＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子２. ９６ｇを純水５８. ５２ｇに均一に分散させ、これに濃度１０重量％のＢａＣｌ₂水溶液１４. ４ｇを加え、３０℃で１時間撹拌した後、限外濾過膜法で流出液の電導度が５０μＳ／ｃｍ以下となるまで洗浄し、ついで酸化物として濃度２０重量％に濃縮した。ついで、１５０℃で乾燥してＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子にＢａＯを担持した改質酸化チタン粒子（Ｄ）３. １ｇを得た。得られた粒子の組成を表１に示し、また耐ＵＶ性を評価し、結果を表１に示した。
【００２３】
〔実施例５〕
酸化チタン粒子（TITANIX 社製：CR-90 、ルチル型酸化チタン、平均粒子径０. ２５μｍ）１４. ５ｇを純水３. ９８ｋｇに均一に分散させ、分散液に濃度２０重量％のＮａＯＨ水溶液３. ６ｇを加えて分散液のｐＨを１０. ５とした。ついで、分散液の温度を９０℃に昇温し、３０分間撹拌した後、ＳｉＯ₂としての濃度が１. ５重量％の希釈３号水硝子４５０ｇとＡｌ₂Ｏ₃としての濃度が０.５重量％のアルミン酸ソーダ４５０ｇとを同時に、連続的に６時間で添加した。ついで、１時間熟成した後、常温に冷却し、限外濾過膜法で洗浄と濃縮を行い酸化物としての濃度が２０重量％のＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子分散液を得た。この分散液を１５０℃で乾燥してＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子２３ｇを得た。
得られたＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子２. ９６ｇを純水５８. ５２ｇに均一に分散させ、これに濃度１０重量％のＢａＣｌ₂水溶液１４. ４ｇを加え、３０℃で１時間撹拌した後、限外濾過膜法で流出液の電導度が５０μＳ／ｃｍ以下となるまで洗浄し、ついで酸化物として濃度２０重量％に濃縮した。ついで、１５０℃で乾燥してＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子にＢａＯを担持した改質酸化チタン粒子（Ｅ）３. １ｇを得た。得られた粒子の組成を表１に示し、また耐ＵＶ性を評価し、結果を表１に示した。
【００２４】
〔実施例６〕
酸化チタン粒子（TITANIX 社製：CR-90 、ルチル型酸化チタン、平均粒子径０. ２５μｍ）１８. ８ｇを純水３. ９８ｋｇに均一に分散させ、分散液に濃度２０重量％のＮａＯＨ水溶液４. ７ｇを加えて分散液のｐＨを１０. ５とした。ついで、分散液の温度を９０℃に昇温し、３０分間撹拌した後、ＳｉＯ₂としての濃度が１. ５重量％の希釈３号水硝子３００ｇとＺｒＯ₂としての濃度が０. ５重量％の塩化ジルコニウム３００ｇとを同時に、連続的に４. ５時間で添加した。ついで、１時間熟成した後、常温に冷却し、限外濾過膜法で洗浄と濃縮を行い酸化物としての濃度が２０重量％のＳｉＯ₂・ＺｒＯ₂被覆酸化チタン粒子分散液を得た。この分散液を１５０℃で乾燥してＳｉＯ₂・ＺｒＯ₂被覆酸化チタン粒子２３ｇを得た。
得られたＳｉＯ₂・ＺｒＯ₂被覆酸化チタン粒子３. ０８ｇを純水５８. ５２ｇに均一に分散させ、これに濃度１０重量％のＢａＣｌ₂水溶液１５ｇを加え、３０℃で１時間撹拌した後、限外濾過膜法で流出液の電導度が５０μＳ／ｃｍ以下となるまで洗浄し、ついで酸化物として濃度２０重量％に濃縮した。ついで、１５０℃で乾燥してＳｉＯ₂・ＺｒＯ₂被覆酸化チタン粒子にＢａＯを担持した改質酸化チタン粒子（Ｆ）３. ２ｇを得た。得られた粒子の組成を表１に示し、また耐ＵＶ性を評価し、結果を表１に示した。
【００２５】
〔実施例７〕
酸化チタン粒子（TITANIX 社製：CR-90 、ルチル型酸化チタン、平均粒子径０. ２５μｍ）１７. ４ｇを純水３. ９８ｋｇに均一に分散させ、分散液に濃度２０重量％のＮａＯＨ水溶液４. ３ｇを加えて分散液のｐＨを１０. ５とした。ついで、分散液の温度を９０℃に昇温し、３０分間撹拌した後、ＳｉＯ₂としての濃度が１. ５重量％の希釈３号水硝子３００ｇとＺｒＯ₂としての濃度が０. ５重量％の塩化ジルコニウム３００ｇとを同時に、連続的に４. ５時間で添加した。ついで、１時間熟成した後、常温に冷却し、限外濾過膜法で洗浄と濃縮を行い酸化物としての濃度が２０重量％のＳｉＯ₂・ＺｒＯ₂被覆酸化チタン粒子分散液を得た。この分散液を１５０℃で乾燥してＳｉＯ₂・ＺｒＯ₂被覆酸化チタン粒子２１. ８ｇを得た。
得られたＳｉＯ₂・ＺｒＯ₂被覆酸化チタン粒子２. ８ｇを純水５８. ５２ｇに均一に分散させ、これに濃度１０重量％のＢａＣｌ₂水溶液２７. ３ｇを加え、３０℃で１時間撹拌した後、限外濾過膜法で流出液の電導度が５０μＳ／ｃｍ以下となるまで洗浄し、ついで酸化物として濃度２０重量％に濃縮した。ついで、１５０℃で乾燥してＳｉＯ₂・ＺｒＯ₂被覆酸化チタン粒子にＢａＯを担持した改質酸化チタン粒子（Ｇ）３. １ｇを得た。得られた粒子の組成を表１に示し、また耐ＵＶ性を評価し、結果を表１に示した。
【００２６】
〔実施例８〕
実施例５と同様にしてＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子２３ｇを得、この被覆酸化チタン粒子２. ９６ｇを純水５８. ５２ｇに均一に分散させ、これに濃度１０重量％のＬａＣｌ₃水溶液１４. ４ｇを加え、３０℃で１時間撹拌した後、限外濾過膜法で流出液の電導度が５０μＳ／ｃｍ以下となるまで洗浄し、ついで酸化物として濃度２０重量％に濃縮した。ついで、１５０℃で乾燥してＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子にＬａ ₂ Ｏ ₃を担持した改質酸化チタン粒子（Ｈ）３. １ｇを得た。得られた粒子の組成を表１に示し、また耐ＵＶ性を評価し、結果を表１に示した。
【００２７】
〔実施例９〕
実施例５と同様にしてＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子２３ｇを得、この被覆酸化チタン粒子２. ９６ｇを純水５８. ５２ｇに均一に分散させ、これに濃度１０重量％のＳｎＣｌ₄水溶液１４. ４ｇを加え、３０℃で１時間撹拌した後、限外濾過膜法で流出液の電導度が５０μＳ／ｃｍ以下となるまで洗浄し、ついで酸化物として濃度２０重量％に濃縮した。ついで、１５０℃で乾燥してＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子にＳｎＯ ₂を担持した改質酸化チタン粒子（Ｉ）３. １ｇを得た。得られた粒子の組成を表１に示し、また耐ＵＶ性を評価し、結果を表１に示した。
【００２８】
〔比較例１〕
酸化チタン粒子（TITANIX 社製：CR-90 、ルチル型酸化チタン、平均粒子径０. ２５μｍ）について耐ＵＶ性を評価し、結果を表１に示した。
【００２９】
〔比較例２〕
実施例１で調製したＳｉＯ₂・Ａｌ₂Ｏ₃被覆酸化チタン粒子について耐ＵＶ性を評価し、結果を表１に示した。
【００３０】
〔比較例３〕
実施例７で調製したＳｉＯ₂・ＺｒＯ₂被覆酸化チタン粒子について耐ＵＶ性を評価し、結果を表１に示した。
【００３１】
【表１】

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to novel titanium oxide particles useful for applications such as paints, optical materials, and cosmetic materials.
[0002]
TECHNICAL BACKGROUND OF THE INVENTION
Titanium oxide particles are widely used for their chemical and physical properties, and are used as white pigments, redox catalysts or catalyst carriers, and as cosmetics and plastic surface coating agents that use UV shielding and hiding power. Furthermore, it is used as an antireflection coating material using high refraction, an antistatic material using electrical conductivity, etc., or used in a functional hard coating material by combining these effects, or a photocatalyst based on a higher band gap. It is used for functions, antibacterial agents, antifouling agents, super hydrophilic coatings, solar cells and the like.
As such titanium oxide particles, rutile type titanium oxide particles, anatase type titanium oxide particles, brookite type titanium oxide particles, and titanium oxide particles modified with these crystalline titanium oxides are used. When these titanium oxides are used for cosmetics, hard coat materials, etc., especially when used in combination with organic substances such as oils and fats, organic oxides, etc., the titanium oxide absorbs ultraviolet rays and activates to cause oxidation of the organic substances. In some cases, the weather resistance, light resistance, durability, and the like are lowered, and the paint is discolored and the resin lens base material is deteriorated.
[0003]
In JP-A-2-264909, JP-A-3-68901, and JP-A-5-2102, there is CeO in titanium oxide.₂Or Fe₂O_ThreeIt is disclosed that the weather resistance is increased and the deterioration of the base resin lens is suppressed by using the composite particles.
In addition, the applicant of the present application disclosed in Japanese Patent Application Laid-Open No. H8-48940 on the surface coating film of a high refractive index plastic lens by titanium oxide and ZrO.₂, Al₂O_Three, SiO₂It is disclosed that light resistance is increased and deterioration of the base resin lens is suppressed by using particles in which the above are compounded. However, although the weather resistance has been improved, it is still insufficient, and there has been a problem of discoloration or coloring due to long-term use.
[0004]
Also when used as a pigment in paints and the like, a titanium dioxide pigment in which titanium oxide base particles are coated with a hydrated oxide of tin and a hydrated oxide of zirconium and further coated with a hydrated oxide of aluminum is disclosed. (Japanese Unexamined Patent Publication No. 57-085859).
Also disclosed is a titanium dioxide pigment in which medium nucleic acid-modified titanium particles are coated with a hydrated oxide of tin and a hydrated oxide of zirconium, then coated with a hydrated oxide of titanium, and further coated with a hydrated oxide of aluminum ( JP, 61-281018, A).
Further, JP-A-6-49387 and JP-A-7-292277 disclose coating with lanthanum oxide or coating with silica, tin oxide, zirconium oxide, and alumina.
[0005]
However, although these also have improved weather resistance, they are still insufficient, and there has been a problem of discoloration or coloring due to long-term use. For this reason, it is calculated | required to suppress the activity of a titanium oxide further, and it is calculated | required making it substantially inactive depending on a use.
Under these circumstances, the present inventors have conducted further research and as a result, coated the surface of the titanium oxide particles with an oxide composed of a silica-based composite oxide and, for example, an alkaline earth metal oxide. Thus, it was found that the activity of titanium oxide can be suppressed, and the present invention was completed.
[0006]
OBJECT OF THE INVENTION
The present invention is substantially inactive, and can be suitably used as a paint, cosmetic, hard coat material, etc. The surface is coated with a coating layer composed of a silica-based composite oxide and other inorganic oxides. It aims to provide quality titanium oxide particles.
[0007]
SUMMARY OF THE INVENTION
The present invention is a titanium oxide particle whose surface is coated with a coating layer comprising a silica-based composite oxide (A) and an inorganic oxide (B), wherein the silica-based composite oxide (A) is represented by the following formula (1): And an inorganic oxide (B) containing Cu, Ag, Mg, Ca, Sr, Ba, Zn, La, Ce, Al, Zr, Pb, Sn, Nb, It is one or more oxides of elements other than M selected from the element group consisting of Ta, Sb, Mo, Fe, and Ni.
SiO₂・ NM_{2 / V}O (1)
(However, M is Mg, Ca, Sr, Ba, Al, Ti, Zr, Sb, or Mo, V is the valence of element M, and n is 0.1 to 1.)
It is preferable that the content of the silica-based composite oxide (A) is in the range of 1 to 45% by weight and the content of the inorganic oxide (B) is in the range of 0.1 to 10% by weight. The element M constituting the silica-based composite oxide (A) is preferably either Al or Zr.
It is preferable that the element which comprises the said inorganic oxide (B) is 1 type, or 2 or more types chosen from Mg, Ca, Sr, and Ba.
It is preferable that the element which comprises the said inorganic oxide (B) is 1 type, or 2 or more types chosen from Ba, La, and Sn.
The coating layer is preferably a composite coating layer in which an inorganic oxide (B) is dispersed in a silica-based composite oxide (A) layer.
In particular, it is preferable that cations of metal elements constituting the inorganic oxide (B) are dispersed in the layer of the silica-based composite oxide (A) by ion exchange.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the modified titanium oxide particles according to the present invention will be specifically described.
Titanium oxide particles
Examples of the titanium oxide particles used in the present invention include conventionally known titanium oxide particles used as pigments, ultraviolet absorbers, high refractive index materials, etc. in paints, cosmetics, hard coat materials and the like. There are no particular restrictions on the crystal form of the titanium oxide particles such as anatase type, rutile type, brookite type, and amorphous type, but rutile type titanium oxide is preferred because it has a higher refractive index and lower activity than anatase type. Moreover, although there is no special restriction | limiting about the magnitude | size of a particle, a shape, etc., a thing of 5 nm-10 micrometers is normally used.
[0009]
Silica-based composite oxide (A)
The silica-based composite oxide (A) constituting the coating layer is composed mainly of silica, and is oxidized by any element selected from Mg, Ca, Sr, Ba, Al, Ti, Zr, Sb, and Mo. It is a complex oxide consisting of a product. Such a composite oxide mainly composed of silica can densely coat titanium oxide particles, and these composite oxides have a structure in which a part of silicon atoms of silica is substituted with the above elements, For this reason, in many cases, the substitution atom portion coordinated to the oxygen atom of silica becomes a negative charge, and the cation can be coordinated in a form that neutralizes this negative charge. The cations at this time include cations existing in the process of forming the composite oxide layer, such as Na⁺Etc. exist. Due to the presence of such cations, the cations of the elements constituting the inorganic oxide (B) described later can be attached and supported on the composite oxide layer in the form of ion exchange, and the coating layer of the present invention is formed. .
Therefore, as a component other than silica constituting the silica-based composite oxide (A), any element that can be substituted with a silicon atom of silica may be used, but as the element (M) that can be more substituted, the Mg, Ca, Sr, Ba, Al, Ti, Zr, Sb, and Mo are mentioned, and Al, Ti, Zr, and Mg are particularly preferable.
[0010]
The content of components other than silica in such a silica-based composite oxide (A) is 0.1 to 1.0, preferably 0.15 to 0.85, in the formula (1). Preferably it is the range of 0.2-0.5. When n is less than 0.1, there are few lattice substitutions of components other than silica, the amount of cations of the elements constituting the inorganic oxide (B) described later is small, and the activity of titanium oxide is not sufficiently suppressed. It becomes. On the other hand, even if n exceeds 1.0, the lattice substitution of components other than silica does not increase further, and the adhesion amount of cations of the elements constituting the inorganic oxide (B) decreases. Depending on the type of component other than silica, a dense silica-based composite oxide (A) layer may not be formed, and thus the activity of titanium oxide is not sufficiently suppressed.
[0011]
Inorganic oxide (B)
The inorganic oxide (B) constituting the coating layer is Cu, Ag, Mg, Ca, Sr, Ba, Zn, La, Ce, Al, Zr, Pb, Sn, Nb, Ta, Sb, Mo, Fe, Ni. It consists of an oxide of one or more elements selected from the element group (E) consisting of, and cations of the elements adhere to the layer of the silica-based composite oxide (A) (hereinafter referred to as ion exchange). It is configured. That is, it is considered that the inorganic oxide (B) is uniformly dispersed in the silica-based composite oxide (A) and constitutes a coating layer combined with the silica-based composite oxide (A).
The reason why the composite coating layer in which the inorganic oxide (B) is introduced into the silica-based composite oxide (A) can suppress the activity of titanium oxide is not necessarily clear, but the following reasons are conceivable. .
(1) The coating layer shields light such as sunlight.
{Circle around (2)} Electrons generated in the titanium oxide particles by ions constituting the inorganic oxide (B) (e^-) Or holes (h⁺) Is suppressed or eliminated by electrical neutralization.
(3) In addition to the above (1) and / or (2), they are isolated from organic substances by the coating layer.
Among the element group (E), Mg, Ca, Sr, and Ba are preferable, and when this type of alkaline earth metal is used, the activity of titanium oxide can be more effectively suppressed.
[0012]
Next, the content of the silica-based composite oxide (A) in the modified titanium oxide particles is preferably 1 to 45% by weight, more preferably 5 to 30% by weight. If this content is less than 1% by weight, the entire surface of the titanium oxide particles may not be covered, and even if it can, the amount of inorganic oxide (B) introduced will be insufficient, and the activity of titanium oxide will be reduced. There may be a case where a sufficient suppression effect cannot be obtained. When the content exceeds 45% by weight, the content of titanium oxide decreases, the characteristics of titanium oxide such as high refractive index and white titanium oxide pigments deteriorate, and the intended use of titanium oxide cannot be sufficiently achieved. There is.
The content of the inorganic oxide (B) in the modified titanium oxide particles is preferably in the range of 0.1 to 10% by weight, more preferably 1 to 5% by weight. When this content is less than 0.1% by weight, the effect of suppressing the activity of titanium oxide may not be sufficiently obtained. On the other hand, it is difficult to introduce the content exceeding 10% by weight, and even if possible, the effect of suppressing the activity of titanium oxide is not further increased.
[0013]
Method for producing modified titanium oxide particles
Then, the manufacturing method of the said modified titanium oxide particle is demonstrated.
[Formation of silica-based composite oxide layer]
First, the titanium oxide particles described above are dispersed in water to prepare an aqueous dispersion of titanium oxide. The concentration of titanium oxide particles in the dispersion is TiO₂Is preferably in the range of 0.1 to 10% by weight, particularly 0.2 to 5% by weight. When the concentration of the titanium oxide particles is less than 0.1% by weight, the concentration is too low, and precipitation of the silica-based composite oxide precursor on the titanium oxide particle surface in the next step does not occur efficiently. The efficiency when concentrating in the process is also poor. When the concentration of the titanium oxide particles exceeds 10% by weight, the concentration is too high and the titanium oxide particles may be aggregated, which is not preferable.
[0014]
Next, an alkali is added to the dispersion to adjust the pH of the dispersion to a range of 9 to 12, particularly 9.5 to 11.5. As the alkali, in addition to alkali metal hydroxides such as NaOH and KOH, basic nitrogen compounds such as ammonia and quaternary amines can be used. When the pH of the dispersion is in the above range, a dense silica-based composite oxide coating is obtained, and the contact between titanium oxide and organic matter is effectively blocked, so that the activity of titanium oxide can be suppressed.
Next, an alkali metal silicate aqueous solution as a silica source and a soluble metal salt aqueous solution of the element (M) are added simultaneously or intermittently to the dispersion to simultaneously hydrate the precursor of the silica-based composite oxide. The product is deposited on the surface of the titanium oxide particles.
Examples of the alkali metal silicate include sodium silicate and potassium silicate. Examples of the soluble metal salt of the element (M) include magnesium chloride, sodium aluminate, titanium chloride, zirconium chloride, antimony chloride, and molybdenum sulfate.
[0015]
At this time, the temperature of the dispersion is usually 50 to 100 ° C., more preferably 65 to 95 ° C., and the addition ratio of the alkali metal silicate and the soluble metal salt of the element (M) is the above formula ( In 1), a predetermined molar ratio n is set.
The addition rate of both aqueous solutions can be appropriately selected depending on the temperature of the dispersion, the formation ratio of the coating layer containing the silica-based composite oxide, and the like, in a range where the dispersion does not gel or agglomerate titanium oxide particles. It is important that the silica-based composite oxide precursor is selectively deposited on the surface of the titanium oxide particles.
After the addition of the aqueous solution, it is preferable to age the dispersion in order to form a denser silica-based composite oxide layer and improve the activity suppression effect of titanium oxide. The aging can be performed at a temperature higher than the temperature at the time of adding the aqueous solution, and can be performed in an autoclave at about 150 ° C. for about 10 minutes to 2 hours.
Next, the dispersion is washed, concentrated as necessary, and then dried in the range of 50 to 150 ° C. to obtain titanium oxide particles having a silica-based composite oxide layer. The washing method is not particularly limited as long as it can remove cations and anions derived from pH adjusters and raw materials. For example, an ultrafiltration membrane method, an ion exchange resin method, an ion exchange membrane, and a dehydration filtration washing method are preferable. It is.
[0016]
[Introduction of inorganic oxide (B) component]
An aqueous dispersion of titanium oxide particles on which the silica-based composite oxide layer obtained above is formed is prepared. The concentration of the titanium oxide particles at this time is preferably in the range of 0.1 to 30% by weight, particularly 1 to 20% by weight as oxide. When the concentration of the titanium oxide particles is less than 0.1% by weight, the concentration is too low and the production efficiency is low. When the concentration of the titanium oxide particles exceeds 30% by weight, the concentration is too high and the titanium oxide particles are uniform. In some cases, the inorganic oxide (B) component precursor may not be uniformly introduced, and the introduction of the inorganic oxide (B) component precursor tends to be uneven.
Then, a metal salt aqueous solution excluding the metal salt (hydrochloride, sulfate, nitrate, etc.) in the element group (E) and excluding the soluble metal salt used for forming the silica-based composite oxide (A), Usually, stirring is performed for about 1 to 60 minutes in a temperature range of 30 to 95 ° C. At this time, as described above, the metal cation of the metal salt is uniformly supported on the silica-based composite oxide mainly by ion exchange.
[0017]
【The invention's effect】
The titanium oxide particles of the present invention are coated with a coating layer composed of a silica-based composite oxide (A) and an inorganic oxide (B) of a specific element. Its activity is effectively suppressed while having concealability. Therefore, the modified titanium oxide particles can be suitably used for paints, cosmetics, hard coat materials, synthetic resin lenses and the like having excellent light resistance and weather resistance.
[0018]
【Example】
Hereinafter, although an example explains, the present invention is not limited by these examples.
[Example 1]
20 g of titanium oxide particles (made by TITANIX: CR-90, rutile titanium oxide, average particle size of 0.25 μm) are uniformly dispersed in 3.98 kg of pure water, and 5 g of 20% by weight NaOH aqueous solution is added to the dispersion. The pH of the dispersion was adjusted to 10.5. Next, the temperature of the dispersion was raised to 90 ° C. and stirred for 30 minutes.₂300 g of diluted No. 3 water glass with a concentration of 1.5% by weight and Al₂O_ThreeAs a result, 300 g of sodium aluminate having a concentration of 0.5% by weight was continuously added in 4.5 hours. Next, after aging for 1 hour, it is cooled to room temperature, washed and concentrated by the ultrafiltration membrane method, and the oxide concentration is 20 wt% SiO.₂・ Al₂O_ThreeA coated titanium oxide particle dispersion was obtained. This dispersion is dried at 150 ° C. to obtain SiO₂・ Al₂O_Three24 g of coated titanium oxide particles were obtained.
[0019]
  Obtained SiO₂・ Al₂O_ThreeCoated titanium oxide particles (3.08 g) were uniformly dispersed in pure water (58.52 g).₂After adding 3.0 g of an aqueous solution and stirring at 30 ° C. for 1 hour, it was washed by an ultrafiltration membrane method until the electric conductivity of the effluent became 50 μS / cm or less, and then concentrated as an oxide to a concentration of 20% by weight. Then, it is dried at 150 ° C. and SiO 2₂・ Al₂O_ThreeCoated titanium oxide particlesBaO2.6 g of modified titanium oxide particles (A) supporting γ were obtained. Table 1 shows the composition of the obtained particles.
  Further, the UV resistance as the activity of the titanium oxide particles was evaluated, and the results are shown in Table 1. The UV resistance is measured by mixing 1 g of modified titanium oxide particles (A) and 3 g of acrylic resin in an agate mortar, collecting this in a crucible, and irradiating it with ultraviolet light using a high pressure mercury lamp (HB-1000-A). The time until the resin was colored was measured.
[0020]
[Example 2]
  18.8 g of titanium oxide particles (manufactured by TITANIX: CR-90, rutile type titanium oxide, average particle size 0.25 μm) are uniformly dispersed in 3.98 kg of pure water, and an aqueous NaOH solution 4 having a concentration of 20% by weight is dispersed in the dispersion. 7 g was added to bring the pH of the dispersion to 10.5. Next, the temperature of the dispersion was raised to 90 ° C. and stirred for 30 minutes.₂150g of diluted No. 3 water glass with a concentration of 1.5% by weight and Al₂O_Three150 g of sodium aluminate having a concentration of 0.5% by weight was continuously added in 3 hours. Next, after aging for 1 hour, it is cooled to room temperature, washed and concentrated by the ultrafiltration membrane method, and the oxide concentration is 20 wt% SiO.₂・ Al₂O_ThreeA coated titanium oxide particle dispersion was obtained. This dispersion is dried at 150 ° C. to obtain SiO₂・ Al₂O_Three19.4 g of coated titanium oxide particles were obtained.
  Obtained SiO₂・ Al₂O_Three2. 49 g of coated titanium oxide particles were uniformly dispersed in 58.52 g of pure water, and this was added with 10% by weight of BaCl.₂After adding 12.1 g of an aqueous solution and stirring at 30 ° C. for 1 hour, it was washed by an ultrafiltration membrane method until the conductivity of the effluent became 50 μS / cm or less, and then concentrated as an oxide to a concentration of 20% by weight. Then, it is dried at 150 ° C. and SiO 2₂・ Al₂O_ThreeCoated titanium oxide particlesBaO2.6 g of modified titanium oxide particles (B) carrying succinate were obtained. The composition of the obtained particles is shown in Table 1, UV resistance was evaluated, and the results are shown in Table 1.
[0021]
Example 3
  17.4 g of titanium oxide particles (manufactured by TITANIX: CR-90, rutile type titanium oxide, average particle size of 0.25 μm) are uniformly dispersed in 3.98 kg of pure water, and an aqueous NaOH solution 4 having a concentration of 20% by weight is dispersed in the dispersion. 35 g was added to bring the pH of the dispersion to 10.5. Next, the temperature of the dispersion was raised to 90 ° C. and stirred for 30 minutes.₂300 g of diluted No. 3 water glass with a concentration of 1.5% by weight and Al₂O_ThreeAs a result, 300 g of sodium aluminate having a concentration of 0.5% by weight was continuously added in 4.5 hours. Next, after aging for 1 hour, it is cooled to room temperature, washed and concentrated by the ultrafiltration membrane method, and the oxide concentration is 20 wt% SiO.₂・ Al₂O_ThreeA coated titanium oxide particle dispersion was obtained. This dispersion is dried at 150 ° C. to obtain SiO₂・ Al₂O_Three21.8 g of coated titanium oxide particles were obtained.
  Obtained SiO₂・ Al₂O_Three2.8 g of coated titanium oxide particles are uniformly dispersed in 58.52 g of pure water, and this is added with 10% by weight of BaCl.₂After adding 27.3 g of an aqueous solution and stirring at 30 ° C. for 1 hour, it was washed by an ultrafiltration membrane method until the electric conductivity of the effluent became 50 μS / cm or less, and then concentrated as an oxide to a concentration of 20% by weight. Then, it is dried at 150 ° C. and SiO 2₂・ Al₂O_ThreeCoated titanium oxide particlesBaO3.1 g of modified titanium oxide particles (C) carrying succinate were obtained. The composition of the obtained particles is shown in Table 1, UV resistance was evaluated, and the results are shown in Table 1.
[0022]
Example 4
  24.6 g of titanium oxide particles (manufactured by TITANIX: CR-90, rutile type titanium oxide, average particle size 0.25 μm) are uniformly dispersed in 3.98 kg of pure water, and an aqueous NaOH solution 6 having a concentration of 20% by weight is dispersed in the dispersion. 16g was added to bring the pH of the dispersion to 10.5. Next, the temperature of the dispersion was raised to 90 ° C. and stirred for 30 minutes.₂As a concentration of 1.5% by weight of diluted No. 3 water glass 100g and Al₂O_ThreeAs a result, 100 g of sodium aluminate having a concentration of 0.5% by weight was continuously added in 1.5 hours. Next, after aging for 1 hour, it is cooled to room temperature, washed and concentrated by the ultrafiltration membrane method, and the oxide concentration is 20 wt% SiO.₂・ Al₂O_ThreeA coated titanium oxide particle dispersion was obtained. This dispersion is dried at 150 ° C. to obtain SiO₂・ Al₂O_Three23 g of coated titanium oxide particles were obtained.
  Obtained SiO₂・ Al₂O_Three2. 96 g of coated titanium oxide particles are uniformly dispersed in 58.52 g of pure water, and 10% by weight of BaCl is added thereto.₂After adding 14.4 g of an aqueous solution and stirring at 30 ° C. for 1 hour, it was washed by an ultrafiltration membrane method until the electric conductivity of the effluent became 50 μS / cm or less, and then concentrated as an oxide to a concentration of 20% by weight. Then, it is dried at 150 ° C. and SiO 2₂・ Al₂O_ThreeCoated titanium oxide particlesBaO3.1 g of modified titanium oxide particles (D) carrying succinate were obtained. The composition of the obtained particles is shown in Table 1, UV resistance was evaluated, and the results are shown in Table 1.
[0023]
Example 5
  14.5 g of titanium oxide particles (manufactured by TITANIX: CR-90, rutile type titanium oxide, average particle size 0.25 μm) are uniformly dispersed in 3.98 kg of pure water, and an aqueous NaOH solution 3 having a concentration of 20% by weight is dispersed in the dispersion. 6 g was added to bring the pH of the dispersion to 10.5. Next, the temperature of the dispersion was raised to 90 ° C. and stirred for 30 minutes.₂As a concentration of 1.5% by weight of diluted No. 3 water glass 450g and Al₂O_ThreeIn addition, 450 g of sodium aluminate having a concentration of 0.5% by weight was continuously added in 6 hours. Next, after aging for 1 hour, it is cooled to room temperature, washed and concentrated by the ultrafiltration membrane method, and the oxide concentration is 20 wt% SiO.₂・ Al₂O_ThreeA coated titanium oxide particle dispersion was obtained. This dispersion is dried at 150 ° C. to obtain SiO₂・ Al₂O_Three23 g of coated titanium oxide particles were obtained.
  Obtained SiO₂・ Al₂O_Three2. 96 g of coated titanium oxide particles are uniformly dispersed in 58.52 g of pure water, and 10% by weight of BaCl is added thereto.₂After adding 14.4 g of an aqueous solution and stirring at 30 ° C. for 1 hour, it was washed by an ultrafiltration membrane method until the electric conductivity of the effluent became 50 μS / cm or less, and then concentrated as an oxide to a concentration of 20% by weight. Then, it is dried at 150 ° C. and SiO 2₂・ Al₂O_ThreeCoated titanium oxide particlesBaO3.1 g of modified titanium oxide particles (E) supporting s were obtained. The composition of the obtained particles is shown in Table 1, UV resistance was evaluated, and the results are shown in Table 1.
[0024]
Example 6
  18.8 g of titanium oxide particles (manufactured by TITANIX: CR-90, rutile type titanium oxide, average particle size 0.25 μm) are uniformly dispersed in 3.98 kg of pure water, and an aqueous NaOH solution 4 having a concentration of 20% by weight is dispersed in the dispersion. 7 g was added to bring the pH of the dispersion to 10.5. Next, the temperature of the dispersion was raised to 90 ° C. and stirred for 30 minutes.₂300g of diluted No. 3 water glass with a concentration of 1.5% by weight and ZrO₂As a result, 300 g of zirconium chloride having a concentration of 0.5% by weight was continuously added in 4.5 hours. Next, after aging for 1 hour, it is cooled to room temperature, washed and concentrated by the ultrafiltration membrane method, and the oxide concentration is 20 wt% SiO.₂・ ZrO₂A coated titanium oxide particle dispersion was obtained. This dispersion is dried at 150 ° C. to obtain SiO₂・ ZrO₂23 g of coated titanium oxide particles were obtained.
Obtained SiO₂・ ZrO₂Coated titanium oxide particles (3.08 g) were uniformly dispersed in pure water (58.52 g).₂After adding 15 g of an aqueous solution and stirring at 30 ° C. for 1 hour, it was washed by an ultrafiltration membrane method until the electric conductivity of the effluent became 50 μS / cm or less, and then concentrated as an oxide to a concentration of 20% by weight. Then, it is dried at 150 ° C. and SiO 2₂・ ZrO₂Coated titanium oxide particlesBaOThus, 3.2 g of modified titanium oxide particles (F) carrying s were obtained. The composition of the obtained particles is shown in Table 1, UV resistance was evaluated, and the results are shown in Table 1.
[0025]
Example 7
  17.4 g of titanium oxide particles (manufactured by TITANIX: CR-90, rutile type titanium oxide, average particle size of 0.25 μm) are uniformly dispersed in 3.98 kg of pure water, and an aqueous NaOH solution 4 having a concentration of 20% by weight is dispersed in the dispersion. 3 g was added to bring the pH of the dispersion to 10.5. Next, the temperature of the dispersion was raised to 90 ° C. and stirred for 30 minutes.₂300g of diluted No. 3 water glass with a concentration of 1.5% by weight and ZrO₂As a result, 300 g of zirconium chloride having a concentration of 0.5% by weight was continuously added in 4.5 hours. Next, after aging for 1 hour, it is cooled to room temperature, washed and concentrated by the ultrafiltration membrane method, and the oxide concentration is 20 wt% SiO.₂・ ZrO₂A coated titanium oxide particle dispersion was obtained. This dispersion is dried at 150 ° C. to obtain SiO₂・ ZrO₂21.8 g of coated titanium oxide particles were obtained.
  Obtained SiO₂・ ZrO₂2.8 g of coated titanium oxide particles are uniformly dispersed in 58.52 g of pure water, and this is added with 10% by weight of BaCl.₂After adding 27.3 g of an aqueous solution and stirring at 30 ° C. for 1 hour, it was washed by an ultrafiltration membrane method until the electric conductivity of the effluent was 50 μS / cm or less, and then concentrated as an oxide to a concentration of 20% by weight. Then, it is dried at 150 ° C. and SiO 2₂・ ZrO₂Coated titanium oxide particlesBaO3.1 g of modified titanium oxide particles (G) carrying succinate were obtained. The composition of the obtained particles is shown in Table 1, UV resistance was evaluated, and the results are shown in Table 1.
[0026]
Example 8
  Similar to Example 5, SiO₂・ Al₂O_Three23 g of coated titanium oxide particles were obtained, and 2.96 g of the coated titanium oxide particles were uniformly dispersed in 58.52 g of pure water, to which LaCl having a concentration of 10% by weight was added._ThreeAfter adding 14.4 g of an aqueous solution and stirring at 30 ° C. for 1 hour, it was washed by an ultrafiltration membrane method until the electric conductivity of the effluent became 50 μS / cm or less, and then concentrated as an oxide to a concentration of 20% by weight. Then, it is dried at 150 ° C. and SiO 2₂・ Al₂O_ThreeCoated titanium oxide particlesLa ₂ O _Three3.1 g of modified titanium oxide particles (H) carrying s were obtained. The composition of the obtained particles is shown in Table 1, UV resistance was evaluated, and the results are shown in Table 1.
[0027]
Example 9
  Similar to Example 5, SiO₂・ Al₂O_Three23 g of coated titanium oxide particles were obtained, and 2.96 g of the coated titanium oxide particles were uniformly dispersed in 58.52 g of pure water, and 10 wt% SnCl was added thereto._FourAfter adding 14.4 g of an aqueous solution and stirring at 30 ° C. for 1 hour, it was washed by an ultrafiltration membrane method until the electric conductivity of the effluent became 50 μS / cm or less, and then concentrated as an oxide to a concentration of 20% by weight. Then, it is dried at 150 ° C. and SiO 2₂・ Al₂O_ThreeCoated titanium oxide particlesSnO ₂3.1 g of modified titanium oxide particles (I) carrying strontium was obtained. The composition of the obtained particles is shown in Table 1, UV resistance was evaluated, and the results are shown in Table 1.
[0028]
[Comparative Example 1]
The UV resistance of titanium oxide particles (manufactured by TITANIX: CR-90, rutile type titanium oxide, average particle diameter of 0.25 μm) was evaluated, and the results are shown in Table 1.
[0029]
[Comparative Example 2]
SiO prepared in Example 1₂・ Al₂O_ThreeThe coated titanium oxide particles were evaluated for UV resistance, and the results are shown in Table 1.
[0030]
[Comparative Example 3]
SiO prepared in Example 7₂・ ZrO₂The coated titanium oxide particles were evaluated for UV resistance, and the results are shown in Table 1.
[0031]
[Table 1]

Claims

Titanium oxide particles having a surface coated with a coating layer composed of a silica-based composite oxide (A) and an inorganic oxide (B), wherein the silica-based composite oxide (A) is represented by the following formula (1) One or two oxides of elements other than M, which is a complex oxide of element M and silicon, and the inorganic oxide (B) is selected from the element group consisting of Mg, Ca, Sr, Ba, La, and Sn Modified titanium oxide particles characterized by being more than seeds.
SiO ₂ · nM _{2 / V} O (1)
(However, M is Mg, Ca, Sr, Ba, Al, Ti, Zr, Sb, or Mo, V is the valence of element M, and n is 0.1 to 1.)

The content of the silica-based composite oxide (A) is in the range of 1 to 45% by weight, and the content of the inorganic oxide (B) is in the range of 0.1 to 10% by weight. The modified titanium oxide particles according to claim 1.

The modified titanium oxide particles according to claim 1, wherein the element M constituting the silica-based composite oxide (A) is either Al or Zr.

The modified titanium oxide particles according to claim 1, wherein the coating layer is a composite coating layer in which the inorganic oxide (B) is dispersed in the silica-based composite oxide (A) layer.

The modified titanium oxide particles according to claim 4, wherein the metal element constituting the inorganic oxide (B) is introduced by ion exchange and dispersed in the layer of the silica-based composite oxide (A).