JP3588419B2 - Zinc oxide-based particles, production method and use thereof - Google Patents

Description

【００７３】
τ（λ）：８００〜１８００ｎｍにおける各透過率
◎：ＴＩＲ＜４５％
○：４５％≦ＴＩＲ＜６５％
△：６５％≦ＴＩＲ＜８０％
×：ＴＩＲ≧８０％
＜透明性＞
濁度計（日本電色工業（株）製ＮＤＨ−１００１ ＤＰ）によりヘイズ（実測値）を測定した。
＜無色性＞
目視で無色性を判定し、下記の評価基準にしたがって評価した。
◎：着色なし
○：僅かに着色、実用上、問題にならない程度
△：若干着色
×：着色目立つ
＜表面抵抗＞
塗膜表面に、金の櫛形電極を蒸着（厚み３０ｎｍ±５ｎｍ）し、温度２５℃、相対湿度５０％、遮光条件下で１時間放置した後、ケスレー社製エレクトロメーター６１７型を用いて、同条件下における表面抵抗値を測定（印加電圧０．１Ｖ）した。
＜耐候性＞
ＪＩＳ Ｂ ７７５３−９３に記載のサイシャインカーボンアーク灯式耐光性および耐候性試験機を用いて、促進耐候性試験を行った。初期１００時間後のヘイズ値および色相を基準にして、さらに２４０時間試験後のヘイズ値および色相を比較して、下記の評価基準にしたがって評価した。
Ａ：ヘイズの変化が２％未満で、且つ、着色（変色）がない。
Ｂ：ヘイズの変化が２％以上、および／または、着色（変色）がある。
＜耐汚染性＞
試験片を屋外で１０日間曝し、表面（塗膜形成側）の汚れ具合を相対評価した。
【００７４】
−実施例１−１−
撹拌機、添加口、温度計、留出ガス出口、窒素ガス導入口を備えた、外部より加熱し得る耐圧１００リットルステンレス（ＳＵＳ３１６）製反応器、および、添加口にボールバルブを介して直結する添加槽、留出ガス出口に直結する冷却器および留出液トラップを備えた反応装置に、ベンジルアルコール２１６３部を仕込み、１５０℃に昇温し、水１．８ｇを混合した。この反応器に添加槽より酢酸亜鉛無水物粉末（関東化学社製、工業用）２０２部およびアルミニウムｓｅｃ−ブトキシド１．２３部を含有するベンジルアルコールスラリー（Ｚｎ添加液）５００部を３０秒かけて混合し、昇温して、２００℃到達後、１時間この温度を保って、粒子分散液１０１７部が得られた。Ｚｎ添加液を混合した時に溶液に含まれる含水量は、Ｚｎに対しモル比で０．１であった。また、昇温過程のボトム温度が１７０℃に達した時点で、カプロン酸を３０重量％含有するベンジルアルコール溶液１９部を１分間かけて、添加槽からボトムに添加した。
【００７５】
得られた分散液（ｄ１）は、表３〜４に示す物性の酸化亜鉛系粒子（Ｐ１）８．０重量％含有するものであった。分散液（ｄ１）の物性および膜透明性を表５に示した。また、分散液（ｄ１）の溶媒は、主に、ベンジルアルコールであったが、この他に酢酸ベンジルが２１重量％含まれていた。分散液中の水分量は、０．１重量％未満であった。
−比較例１−１−
実施例１−１で用いたＺｎ添加液を、酢酸亜鉛２水和物粉末２２０部、アルミニウムｓｅｃ−ブトキシド１．２３部、酢酸４１部、イオン交換水５４部およびベンジルアルコール１８３．７７部を混合した添加液５００部に変更する以外は、実施例１−１と同様に反応を行い、粒子濃度１０重量％の分散液（ｃｄ１）を得た。Ｚｎ添加液を混合した時に溶液に含まれる含水量は、Ｚｎに対しモル比で５．１であった。分散液（ｃｄ１）は、表３〜４に示す物性の酸化亜鉛系粒子（ＣＰ１）を含有するものであった。分散液（ｃｄ１）の物性および膜透明性を表５に示した。
【００７６】
−実施例１−２−
実施例１−１で、アルミニウムｓｅｃ−ブトキシド１．２３部の代わりに、酢酸インジウム２水和物１０．７５部を用いる以外は、実施例１−１と同様に反応を行い、粒子濃度７．５重量％の分散液（ｄ２）を得た。Ｚｎ添加液を混合した時に溶液に含まれる含水量は、Ｚｎに対しモル比で０．１８であった。分散液（ｄ２）は、表３〜４に示す物性の酸化亜鉛系粒子（Ｐ２）を含有するものであった。分散液（ｄ２）の物性および膜透明性を表５に示した。
−比較例１−２−
比較例１−１で、アルミニウムｓｅｃ−ブトキシド１．２３部の代わりに、酢酸インジウム２水和物１０．７５部を用いる以外は、比較例１−１と同様に反応を行い、粒子濃度９．７重量％の分散液（ｃｄ２）を得た。Ｚｎ添加液を混合した時に溶液に含まれる含水量は、Ｚｎに対しモル比で５．２であった。分散液（ｃｄ２）は、表３〜４に示す物性の酸化亜鉛系粒子（ＣＰ２）を含有するものであった。分散液（ｃｄ２）の物性および膜透明性を表５に示した。
【００７７】
−実施例１−３〜１−１１−
実施例１−１と同様の反応器を用いて、表１〜２に示した亜鉛化合物、温度条件等で、反応を行い、それぞれ、酸化亜鉛系粒子（Ｐ３）〜（Ｐ１１）を含有する分散液（ｄ３）〜（ｄ１１）を得た。
上記で得られた酸化亜鉛系粒子（Ｐ３）〜（Ｐ１１）の物性を、それぞれ、表表３〜４に示した。分散液（ｄ３）〜（ｄ１１）およびその膜透明性を、それぞれ、表５に示した。
酸化亜鉛系粒子（Ｐ７）〜（Ｐ１１）は、表２に記載の表面処理剤で処理されており、その表面は光触媒不活性な水酸化物モノマー、オリゴマーまたは酸化物の薄い膜で処理されている。
【００７８】
【表１】

【００７９】
【表２】

【００８０】
（表１および２の注）
＊１：酢酸水溶液を含有したベンジルアルコール
１．亜鉛化合物として用いた酢酸亜鉛無水物は、市販品を粉砕した後に使用した。その比表面積は、１３ｍ^２／ｇであった。
２．上記混合方法は、亜鉛化合物と、金属元素（Ｍ）の化合物と、アルコールとを混合する方法であり、以下のＡ〜Ｅのいずれかの方法で行った。
Ａ：アルコールに亜鉛化合物を添加した後、酸化亜鉛系粒子が析出するまでの間にＭの化合物をさらに添加する。
Ｂ：亜鉛化合物およびＭの化合物を混合して得られた混合物を、アルコールに添加する。
Ｃ：アルコール中にＭの化合物を溶解させておいて、亜鉛化合物をさらに添加する。
Ｄ：アルコールに亜鉛化合物を添加した後、酸化亜鉛系粒子が析出するまでの間に、Ｍの化合物およびＭ’の化合物（Ｍ’の酢酸塩）をさらに添加する。
Ｅ：亜鉛化合物、Ｍの化合物およびＭ’の化合物（Ｍ’の酢酸塩）を混合して得られた混合物を、アルコールに添加する。
【００８１】
３．表面処理剤は、溶媒と同じアルコールに溶解させ、５０％の濃度に調製し、粒子が析出してから１時間後に添加する。
４．添加剤はカルボキシル基含有化合物であり、溶媒と同じアルコールに溶解させ、３０％の濃度に調製し、粒子が析出してから５分後に添加する。添加量はＺｎに対し５モル％である。
５．亜鉛化合物の添加形態が懸濁液の場合は、亜鉛化合物の固形分濃度が、４０重量％のスラリーを用いた。
【００８２】
【表３】

【００８３】
【表４】

【００８４】
不純物Ｈの量は、いずれの粒子もＺｎに対し０．００１モル％未満であった。
【００８５】
【表５】

【００８６】
−実施例２−１−
実施例１−１で得られた分散液（ｄ１）を遠心分離して、粒子濃度５０重量％のケーキを得た。このケーキをトルエン中に粒子濃度７重量％となるように再分散させ、再び、遠心分離して、再度得られたケーキをトルエンに分散させて、粒子濃度４０重量％のトルエン分散体（ＤＥ１）を調製した。
−実施例２−２〜２−８および比較例２−１〜２−２−
表６に示した分散液および溶媒を用い、表６に示す調製方法で、それぞれ、分散体を調製した。なお、実施例２−８では、可塑剤を溶媒して用いた。
【００８７】
【表６】

【００８８】
−実施例３−１−
分散体（ＤＥ１）にバインダー樹脂として、表７に示すアクリル樹脂溶液（Ｂ１）を添加混合し、サンドミルを用いて分散処理した。さらに、硬化剤としてのイソシアヌレート変性ヘキサメチレンジイソシアナートを添加混合し、２５℃で３０分間攪拌して、塗料（１）を調製した後、これをＰＥＴフィルムに塗布し、熱風乾燥機で９０℃で２分間乾燥して、フィルム状の塗工品（１）を得た。塗工品（１）の評価結果を表８に示した。
−実施例３−２〜３−３および比較例３−１〜３−２−
実施例３−１と同様にして、表７に示したバインダー樹脂、実施例２で製造した各分散体、必要に応じて硬化剤、硬化触媒からなる、塗料（２）〜（３）および塗料（ｃ１）〜（ｃ２）を調製し、実施例３−１と同様にして、フィルム状の塗工品（２）〜（３）および塗工品（ｃ１）〜（ｃ２）を得た。これらの塗工品の評価結果を表８に示した。
【００８９】
【表７】

【００９０】
【表８】

【００９１】
（表８の注）
１．硬化剤としてイソシアヌレート変性ヘキサメチレンジイソシアナートを使用し、バインダー樹脂の水酸基量と当量となるように添加した。
２．各塗料中に含まれる固形分濃度は、いずれも、５０重量％である。
３．塗料を塗布後、いずれも、９０℃で２分間、熱風乾燥した。
表８から、塗工品（１）は、塗工品（ｃ１）と比較して、紫外線遮蔽性および透明性に優れる。塗工品（２）は、塗工品（ｃ２）と比較して、紫外線遮蔽性、熱線遮蔽性および透明性に優れる。塗工品（３）は、紫外線遮蔽性、熱線遮蔽性および透明性に優れ、さらに、耐候性にも優れる。
【００９２】
また、塗工品（１）〜（３）の塗膜側の表面抵抗を評価した結果、塗工品（１）では１０^１３Ω／□オーダー、塗工品（２）では帯電防止レベル（１０^６〜１０^９Ω／□オーダー）、塗工品（３）では静電防止レベル（１０^１０〜１０^１１Ω／□オーダー）であった。
−実施例３−４〜３−５−
実施例３−１と同様にして、分散体（ＤＥ５）にバインダー樹脂として、表７に示すフッ素樹脂溶液（Ｂ３）を添加混合し、サンドミルを用いて分散処理した。さらに、硬化剤としてのイソシアヌレート変性ヘキサメチレンジイソシアナートを添加混合し、２５℃で３０分間攪拌して、塗料（４）〜（５）を調製した後、これをフッ素フィルムに塗布し、熱風乾燥機で１０５℃で２分間乾燥して、フィルム状の塗工品（４）〜（５）を得た。これらの塗工品の評価結果を表９に示した。
【００９３】
−比較例３−３−
分散体（ＤＥ５）を用いない以外は実施例３−４と同様にして、塗料（ｃ３）を調製し、実施例３−４と同様にして、フィルム状の塗工品（ｃ３）を得た。これらの塗工品の評価結果を表９に示した。
塗工品（ｃ３）は絶縁性であったが、塗工品（４）〜（５）は、帯電防止性および静電防止性を有していた。また、耐汚染性は、塗工品（４）＞塗工品（５）＞塗工品（ｃ３）の順番に低下した。
−実施例３−６−
表９に示す塗料（６）を、実施例３−４と同様にして調製し、塩化ビニルフィルムに塗布し、熱風乾燥機で１０５℃で２分間乾燥して、フィルム状の塗工品（６）を得た。これらの塗工品の評価結果を表９に示した。
【００９４】
塗工品（６）は、帯電防止性を有し、塗膜が形成されていない塩化ビニルフィルム（比較例３−４）と比較して、耐汚染性が改善された。
【００９５】
【表９】

【００９６】
（表９の注）
１．実施例３−４〜３−５および比較例３−３では、硬化剤としてイソシアヌレート変性ヘキサメチレンジイソシアナートを使用し、バインダー樹脂の水酸基量と当量となるように添加した。
２．各塗料中に含まれる固形分濃度は、いずれも、４０重量％である。
３．基材の厚みは、フッ素フィルムでは７０μｍ、塩化ビニルフィルムでは１００μｍであった。
４．塗料を塗布後、いずれも、１０５℃で２分間、熱風乾燥した。
【００９７】
−実施例３−７〜３−９−
表１０に示す塗料（７）〜（９）を、実施例３−４と同様にして調製し、基材に塗布し、乾燥して、塗工品（７）〜（９）を得た。これらの塗工品の評価結果を表１０に示した。
これらの塗工品は、いずれも、紫外線遮蔽性、熱線遮蔽性、透明性および無色性に優れるものであった。
【００９８】
【表１０】

【００９９】
（表１０の注）
１．実施例３−７では硬化触媒としてジブチルスズジラウレートを用い、実施例３−９では硬化剤としてメラミン樹脂を用いた。
２．基材の厚みは、ポリカーボネート樹脂板（ＰＣ板）では３ｍｍ、ガラス板では１．５ｍｍであった。
３．塗料を塗布後、実施例３−７では、１）常温６０時間後、２）１００℃で２時間乾燥した。実施例３−８では、１）常温６０時間後、２）１００℃で２時間乾燥し、３）窒素雰囲気下、３００℃で１時間焼き付けた。実施例３−９では、１８０℃で２０分間焼き付けた。
【０１００】
−実施例３−１０−
実施例２−８で得られた分散体（ＤＰ１１）２１部を、ジオクチルフタレート２０部に混合し、この混合物をポリビニルブチラール樹脂１００部に混合、混練して、粒子を１．５重量％分散含有した樹脂組成物を得た。この樹脂組成物を押出し成形機で成形し、厚み０．８ｍｍのポリビニルブチラールシートを得た。
このシートを厚み３ｍｍの板ガラスに挟み、減圧下、１００℃で１時間保持した後、常温にしてからオートクレーブ装置に入れ、圧力８ｋｇ／ｃｍ^２、温度１３０±７℃で、３０分間処理して、積層ガラスを得た。
【０１０１】
この積層ガラスは、紫外線遮蔽性の透明合わせガラスであり、紫外線遮蔽性が◎、可視光透過性が◎、透明性がヘイズ０．３％であった。
−実施例３−１１−
実施例２−４で得られた分散体（ＤＥ６）にテトラエトキシシランを、酸化亜鉛系粒子／ＳｉＯ_２＝９５／５（重量比）、全固形分濃度２０重量％の塗布液を調製した。この塗布液を、予め、シリカ膜が形成されたガラス板に塗布し、１００℃で、乾燥した後、窒素雰囲気下、６００℃で１時間加熱処理して、酸化物膜が形成されたガラス板を得た。
【０１０２】
このガラス板は、膜厚１．６μｍであり、表面抵抗が４×１０^８Ω／□、紫外線遮蔽線が◎、熱線遮蔽性が◎、透明性がヘイズ０．１％以下、無色性が◎であった。
−実施例３−１２−
実施例２−５で得られた水系の分散体（ＤＥ９）とアクリル樹脂エマルションを混合して、塗料を調製した。この塗料に含まれる固形分中の粒子の濃度は、２０重量％であった。この塗料にナイロン繊維を浸漬し、乾燥させて、粒子目付量３ｇ／ｍ^２の繊維を得た。この繊維は、帯電防止性および耐候性に優れるものであった。
【０１０３】
−実施例３−１３−
実施例１−４で得られた分散液（ｄ４）をエバポレーターを用いて減圧濃縮して、さらに乾固させて、８０℃で真空乾燥させて、粒子粉体を得た。この粒子粉体３部およびポリカーボネート樹脂ペレット１０００部を溶融混練して、粒子が０．３重量％分散含有した組成物を得た。この組成物をシート状に押出し成形して、厚さ３ｍｍのポリカーボネートシートを得た。
得られたポリカーボネートシートは、紫外線遮蔽性が◎、可視光透過性が○、熱線遮蔽性が◎であった。
【０１０４】
−実施例３−１４−
実施例２−５で得た分散体（ＤＥ６）２５０部と、アクリル樹脂（ＯＨＶ５０／樹脂、固形分樹脂濃度５０重量％）６０部、硬化剤樹脂（イソシアヌレート変性ヘキサメチレンジイソシアナート、ＮＣＯ基２３重量％含有）５部からなる塗料を調製した。この塗料を厚さ２５μｍのＰＥＴフィルム（基材フィルム）の片面（コロナ処理済）に、グラビアコート法で、乾燥膜厚４．３μｍＪなるように成膜、乾燥（９５℃、２分間）して、粒子分散被膜を設けたＰＥＴフィルムを得た。
【０１０５】
次に、この粒子分散被膜を設けたＰＥＴフィルムの分散膜側に、アクリル系粘着剤をコンマコーターで、乾燥膜厚１６μｍとなるように塗工した。この塗工面に、離型処理したＰＥＴフィルム（剥離フィルム、厚み５０μｍ）を張り合わせて基材フィルム、酸化亜鉛系微粒子分散層、粘着剤層、剥離フィルム層からなる積層フィルムを得た。
この積層フィルムは、紫外線遮蔽性に優れた粘着性の積層フィルムであり、紫外線遮蔽性が◎、可視光透過性が○、熱線遮蔽性が◎、透明性がヘイズ４％未満、無色性が◎であった。
【０１０６】
−実施例３−１５−
実施例３−１４において、基材フィルムとして、あらかじめ、紫外線硬化型のウレタンアクリレート樹脂からなるハードコート層（被膜厚２μｍ）を形成してなるＰＥＴフィルムを使用し、ハードコート層の片面に、実施例３−１４と同様にして、順次、酸化亜鉛系微粒子分散層、粘着剤層、剥離フィルム層を形成した積層フィルムを得た。この積層フィルムは、紫外線遮蔽性、熱線遮蔽性、透明性、耐光性、耐候性および耐擦傷性に優れるものであった。
【０１０７】
【発明の効果】
本発明にかかる酸化亜鉛系粒子は、紫外線遮蔽性または熱線遮蔽性に優れた新規な粒子である。
本発明にかかる酸化亜鉛系粒子の製造方法は、上記酸化亜鉛系粒子を再現性良く、しかも、効率よく製造することができる。
本発明にかかる酸化亜鉛系粒子含有組成物は、紫外線遮蔽性または熱線遮蔽性に優れた塗膜等を形成できる。
本発明にかかる塗装品は、紫外線遮蔽性または熱線遮蔽性に優れる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to novel zinc oxide-based particles, a method for producing the same, and uses.
[0002]
[Prior art]
2. Description of the Related Art Zinc oxide particles having conductivity and heat-ray shielding properties have been known, and applications to conductive paints and heat-ray shielding paints have been proposed. However, all of these particles are manufactured by doping a group 3B or group 4B metal element in order to impart conductivity and heat ray shielding property to zinc oxide. There is a problem that the ultraviolet ray shielding property, which is a physical property of the composition, is reduced.
In order to solve this problem, the present inventors have developed zinc oxide-based particles containing a 3B or 4B metal element.Crystallizing in the liquid phaseIt was manufactured (see JP-A-8-253317). These particles have high heat-ray shielding properties, and the problem of ultraviolet shielding properties is slightly improved. However, when these particles are incorporated into a paint or the like, it is necessary to make the coating thicker or increase the amount of zinc oxide-based particles contained in the paint to improve the ultraviolet shielding property. For this reason, the coating cost was increased, and the problem of ultraviolet shielding properties was not completely solved.
[0003]
On the other hand, there is a problem that the zinc oxide-based particles have a bluish hue with respect to heat ray shielding properties. In recent years, there has been a high demand for satisfying both high transparency to visible light and high shielding to heat rays.
[0004]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a novel zinc oxide-based particle excellent in ultraviolet ray shielding property or heat ray shielding property, a method for producing the same, and a use thereof.
[0005]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above-mentioned problems. As a result, in order to enhance the ultraviolet shielding property, the ultraviolet transmission end TI by powder diffuse reflectance measurement was measured._uvIs required to be 370 nm or more. In addition, the inventors have found that it is necessary to set the reflectance at a wavelength of 1000 nm to the maximum reflectance at a wavelength of 380 to 780 nm in a certain range in order to enhance the heat ray shielding property, and completed the present invention.
That is, the present inventionAcidZinc oxide-based particles are trivalent and / or tetravalent metal elements (M) And Zn as metal components, and exhibiting zinc oxide crystallinity in X-ray diffraction.MIs 0.1 to 20 atomic% with respect to Zn, and an ultraviolet transmission end TI obtained by powder diffuse reflectance measurement._uvBut TI_uv≧ 370 nm.
[0006]
According to the present inventionAcidZinc oxide-based particles areIn the above,The reflectance at a wavelength of 1000 nm obtained by powder diffuse reflectance measurement is R (1000), and the maximum reflectance at a wavelength of 380 to 780 nm is R (λ)._max), R (1000) / R (λ_maxSatisfies <0.8Is preferred.
The method for producing a zinc oxide-based particle according to the present invention is characterized in that a zinc compound and / or a hydrolytic condensate thereof and a trivalent and / or tetravalent metal element (MIn the method for producing zinc oxide-based particles, wherein the zinc oxide-based particles are precipitated from a solution obtained by mixing the compound and / or a hydrolyzed condensate thereof and an alcohol, the solution is a zinc compound represented by the following general formula: The compound represented by (I) is used,MIs 0.1 to 20 atomic% with respect to Zn, and the water content is adjusted to be 4 or less in molar ratio with respect to Zn.
[0007]
Zn (O)_k(OCOR)_x(OH)_y(OR ')_z      (I)
(However, R is at least one selected from a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group and an aralkyl group; R ′ is at least one selected from an alkyl group, a cycloalkyl group, an aryl group and an aralkyl group One kind; k, x, y and z satisfy k = (2-xyz) / 2, x + y + z ≦ 2, 0 <x ≦ 2, 0 ≦ y <2, and 0 ≦ z <2. )
The zinc oxide-based particle-containing composition according to the present invention contains the zinc oxide-based particles and a binder component, and the ratio of the zinc oxide-based particles to the total solid content of the two is 0.1 to 99% by weight. A composition.
[0008]
The first coated body according to the present invention is a coated body obtained by forming a coating film obtained from the composition containing zinc oxide particles on the surface of a substrate.
The second coated body according to the present invention is a coated body formed by applying a liquid containing the above zinc oxide-based particles and a solvent to the surface of a base material and heating the base material to form a thin film.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
(Zinc oxide particles)
The zinc oxide-based particles of the present invention exhibit ultraviolet ray shielding properties by absorbing the inherent ultraviolet rays of the zinc oxide-based particles, visible light transmittance, heat ray shielding properties, conductivity, colorless transparency, etc., and dispersibility. High particles.
Zinc oxide-based particles are trivalent and / or tetravalent metal elements (M) And Zn are metal components.MIs preferably 0.1 to 20%, more preferably 1 to 10%, further preferably 2 to 8%, and most preferably the ratio of the number of M atoms to the total number of Zn atoms. 3-6%. Exceeding the above range makes it difficult to obtain fine particles having a high degree of uniformity in composition, crystal size, and the like, and below the above range results in insufficient heat ray shielding properties.
[0010]
Examples of the additive element M include B, Al, Ga, In, Tl, C, Si, Ge, Sn, Pb, and other Group III / B and IVB elements, as well as Sc, Y, Ti, Zr, and Hf. , V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Rh, Ir, La, Ce, Sb and the like. Among these, at least one selected from Al, Ga and In is preferable, and the conductivity and the heat ray shielding property are enhanced. Compared to the case of adding each alone by a synergistic effect, since colorless transparency, heat ray shielding properties and conductivity are further increased,MIs preferably two or more, more preferably at least one selected from Al, Ga and In, most preferably two selected from Al, Ga and In.
[0011]
The content of M in the zinc oxide-based particles is not particularly limited, but is preferably 0.1 to 8 atomic%, more preferably 0.4 to 4 atomic% based on Zn.MIf the content is less than 0.1 atomic%, the conductivity and the heat ray shielding property may be reduced. On the other hand,MIf the content exceeds 8 atomic%, secondary aggregation is likely to occur, and the dispersibility may be reduced. Zinc oxide particles with excellent heat ray shielding propertiesMThe content is 0.8 to 5 atomic% based on Zn.
MIs composed of two types,MThe total content is preferably 0.4 to 5 atomic% with respect to Zn.MOne ofM ₁The otherM ₂As each compounding ratio (M ₁andM ₂Of the total atomic weight ofM ₁Is preferably 10 to 90 atomic%.
[0012]
In the present invention, the ultraviolet transmitting end TI_uvIs defined as the wavelength at which the reflectance is [R (350) +2] (%), where R (350) (%) is the reflectance at 350 nm obtained by powder diffuse reflectance measurement. The powder diffuse reflectance measurement will be described in detail below. In the zinc oxide particles of the present invention, TI_uv≧ 370 nm, preferably TI_uv≧ 372 nm, more preferably TI_uv≧ 374 nm. TI_uvIf it is less than 370 nm, the ultraviolet shielding properties will decrease.
In the zinc oxide-based particles of the present invention, the reflectance at a wavelength of 1000 nm obtained by powder diffuse reflectance measurement is R (1000), and the maximum reflectance at a wavelength of 380 to 780 nm is R (λ)._max), R (1000) / R (λ_max) <0.8. Here, R (1000) / R (λ_max) Is preferably R (NIR) <0.6, more preferably R (NIR) <0.3. When R (NIR) is 0.8 or more, the heat ray shielding property when included in a coating film or the like is reduced.
[0013]
In the zinc oxide-based particles of the present invention, the reflectance at a wavelength of 780 nm obtained by powder diffuse reflectance measurement is R (780), and the maximum reflectance at a wavelength of 380 to 780 nm is R (λ)._max), R (780) / R (λ_max)> 0.3. Here, R (780) / R (λ_max) As R (BL), more preferably R (BL)> 0.4, still more preferably R (BL)> 0.6, particularly preferably R (BL)> 0.8. When R (BL) is 0.3 or less, even if it is transparent when included in a coating film or the like, it may be colored blue and the colorless transparency may be reduced.
[0014]
In the zinc oxide-based particles of the present invention, 800 kg / cm²Is preferably ρB <1 × 10⁹Ω · cm, more preferably 1 × 10³Ω · cm <ρB <1 × 10⁷Ω · cm, most preferably 1 × 10⁴Ω · cm <ρB <1 × 10⁵Ω · cm. ρB is 1 × 10⁹If it is Ω · cm or more, the conductivity may be reduced.
The zinc oxide-based particles need to exhibit zinc oxide crystallinity in X-ray diffraction, and it is preferable that the primary particles of the zinc oxide-based particles are dispersed without secondary aggregation.
The dispersed particle size Dd of the zinc oxide-based particles is 0.5 μm or less from the viewpoint of high transparency and substantially not affecting the hue of the composition containing the zinc oxide-based particles, and from the viewpoint of the efficiency of shielding infrared rays. Is preferred. It is more preferably 0.1 μm or less, and further preferably 0.05 μm or less. In particular, it is preferably 0.03 μm or less. It is preferable that the monodispersity is high from the viewpoints of colorless transparency and infrared shielding properties. The monodispersity is defined by a ratio R (Dd / Dw) between the crystallite diameters Dw and Dd described below, and R is preferably 4 or less, more preferably 2 or less, and particularly 1.5 or less. Is preferred.
[0015]
The dispersed particle diameter Dd is a weight-based average particle diameter that can be measured by a dynamic light scattering method, a centrifugal sedimentation method, or the like. When it is less than 0.1 μm, the former value is measured, and when it is 0.1 μm or more, the latter value is measured.
The zinc oxide-based particles include those in which a polymer forms a matrix and particles are dispersed in the matrix (polymer composite particles). Become. The content of the zinc oxide-based particles in the particles is not particularly limited, but is preferably in the range of 1 to 90% by weight based on the total amount of the composite particles in terms of zinc oxide.
[0016]
Examples of the polymer used for the composite include an acrylic resin polymer, an alkyd resin polymer, an amino resin polymer, a vinyl resin polymer, an epoxy resin polymer, a polyamide resin polymer, a polyimide resin polymer, a polyurethane resin polymer, and a polyester. In addition to resin-based polymers, phenolic resin-based polymers, organopolysiloxane-based polymers, acrylic silicone resin-based polymers, polyalkylene glycols, etc., polyolefin-based polymers such as polyethylene and polypropylene, polystyrene-based polymers, fluoroplastic-based thermoplastics and the like Curable resin; synthetic rubber or natural rubber such as ethylene-propylene copolymer rubber, polybutadiene rubber, and acrylonitrile-butadiene rubber; and polysiloxane group-containing polymer. It can be.
[0017]
The shape of the composite particles is preferably spherical or elliptical spherical. Regardless of the outer shape of the particles, it is preferable that the surface has rich irregularities. This is because if the surface has irregularities, the affinity for the binder component and the like in the coating film and the like containing the composite particles increases. The average particle size of the composite particles is not particularly limited, but is usually in the range of 0.001 to 10 μm.
Zinc oxide-based particles are monovalent or divalent metal elementsM 'ToTrivalent and / or tetravalent metal element MAgainstM '0.00001 ≦M '/MIt is preferable that it is contained in the range of ≦ 1. 0.0001 ≦M '/MMore preferably, it is in the range of ≦ 0.4. The atomic ratio to zinc is preferably in the range of 0.0001 to 2%.M 'Is present in the ZnO crystalMIs contained homogeneously (in a more monomeric state), the crystal surface is stabilized, and secondary aggregation and coarse crystal growth are suppressed. Therefore, it becomes a fine crystal with high monodispersity,MBy increasing the amount, it is also possible to improve infrared shielding properties while being excellent in colorless transparency.M 'If the amount is too small, the effect does not appear,M 'If the amount is too large, the weather resistance of the coating containing the particles may decrease. Monovalent or divalent metal elementM 'Is an alkali metal element and / or an alkaline earth metal element, such as lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium and the like. Of these, alkaline earth metal elements are preferred.
[0018]
The zinc oxide-based particles contain ions and / or atoms of halogen elements other than F (that is, chlorine Cl, bromine Br, iodine I) and sulfate SO₄ ^2-And nitrate NO₃ ⁻(Hereinafter, may be referred to as impurity H) in the ratio of the number of atoms to zinc (calculated as the number of S atoms in the case of sulfate, and the number of N atoms in the case of nitrate). Preferably it is 0.5% or less. It is more preferably at most 0.1%, further preferably at most 0.01%, particularly preferably at most 0.001%. This includes the case where no impurity H is contained. Only when the impurity H is not contained or does not exceed this range even if the impurity H is contained, particles having excellent infrared shielding properties can be obtained.
[0019]
Conventionally, as a measure of the size and colorless transparency of the fine particles, the particle size or specific surface area measured by an electron microscope has been used as the primary particle size, but is a diffraction peak unique to crystalline zinc oxide, Diffraction peaks are shown at lattice planes (100), (002), and (101). When the following crystallite parameters are satisfied, visible light transmission is good, coloring is suppressed, and colorless transparency is increased. It was revealed.
Zinc oxide-based particles are available from Scherrer.) LawIn Cauchy(Cauchy) function approximationIs used to determine the size Ds (hkl) of the crystallite in the direction perpendicular to each diffraction plane (hkl), it satisfies Ds (002) / Ds (100) <1.5, preferably Ds (002) / Ds (100) <1.2, more preferably Ds (002) / Ds (100) <1.1, even more preferably 0.2 <Ds (002) / Ds (100) <1.0. , And most preferably 0.4 <Ds (002) / Ds (100) <0.8. This is because, when it is in this range, the visible light transmittance and the colorless transparency are excellent.
[0020]
Ds (002) is not particularly limited, but is preferably 1 nm <Ds (002) <30 nm, more preferably 5 nm <Ds (002) <20 nm, and most preferably 5 nm <Ds (002) <15 nm.
AndWilson (Wilson)When the size of the crystallite obtained by the method is Dw, it is preferably in the range of 1 nm <Dw <30 nm, more preferably 5 nm <Dw <20 nm, and still more preferably 5 nm <Dw <15 nm. If Dw is too small, the ultraviolet ray shielding properties and infrared ray shielding properties decrease, and if it is too large, the colorless transparency decreases. When Dw is in the above range, the colorless transparency, infrared ray shielding property and ultraviolet ray shielding property are excellent.
[0021]
Wilson (Wilson)When the lattice distortion of the crystallite obtained by the method is defined as Aw, it is preferable to satisfy 0% ≦ Aw ≦ 1%, more preferably 0% ≦ Aw ≦ 0.5%. When Aw is within the above range,MIs considered to be more monomerically contained, but the infrared shielding property is highest.
The morphology of the zinc oxide particles used in the present invention, such as the shape and particle diameter, is not particularly limited.
Specific examples of the shape include a flaky shape such as a spherical shape, an elliptical spherical shape, a cubic shape, a rectangular shape, a pyramid shape, a needle shape, a column shape, a rod shape, a tubular shape, a scale shape, a (hexagonal) plate shape, and the like. Preferably, the crystallite morphology is in the above-mentioned range, that is, it is flaky.
[0022]
The zinc oxide-based particles of the present invention preferably contain a carboxylic acid (residual) group. The carboxylic acid (residue) group in the present invention means a -COO- group, and specifically, a carboxyl group (-COOH), a carboxylate group (-COO-^-), And an ester group that produces a carboxyl group and / or a carboxylate group by hydrolysis.
Carboxylic acid (remaining) groups are present on the surface of the zinc oxide particles by adsorption and / or chemical bonding, etc., whereby secondary aggregation is suppressed, dispersibility is improved, and transparency is obtained when used as a paint or the like. Will be higher.
[0023]
As the carboxylic acid (residual) group, a saturated fatty acid (remaining) group is preferable, a fatty acid (remaining) group having 1 to 4 carbon atoms is more preferable, and an acetoxy group (CH₃COO-) is most preferred.
The content of the carboxylic acid (residual) group is preferably 0.01 to 7%, more preferably 0.1 to 4%, as a molar ratio to Zn. The presence of the carboxylic acid (residual) group on the particle surface suppresses secondary aggregation, increases colorless transparency, and enhances ultraviolet shielding properties and heat ray shielding properties. On the other hand, when the amount of the carboxylic acid (remaining) group is too large, the infrared shielding property is reduced. When the amount of the carboxylic acid (residual) group is in the above range, both monodispersity and infrared shielding performance are excellent. Further, the zinc oxide-based particles may contain a carbonate group in a weight ratio to ZnO of 10% or less, preferably 3% or less.
[0024]
The zinc oxide particles may be treated with a surface treatment agent for the purpose of reducing the photocatalytic activity of the zinc oxide and imparting weather resistance.
As the surface treatment agent, the above-mentioned polymers can be used, but for the purpose of imparting weather resistance, at least one selected from metal carboxylate and metal alkoxide is preferable. As metal elements in metal carboxylate and metal alkoxide, corresponding (hydr) oxides such as Si, Zr, Al, La, Y, Mg, Ca, Sr, Ba, Be, In, and Sn are in the visible region. A metal element which does not absorb and is easily available is preferred.
As the metal carboxylate, a carboxylate is preferable. Further, as the metal alkoxide, a compound represented by the following general formula (1) is preferable.
[0025]
M^a(OR^a)_mnR^b _m      (1)
(However, M^aIs a metal atom; R^aIs at least one selected from a hydrogen atom, an optionally substituted alkyl group, a cycloalkyl group, an acyl group, an aralkyl group, and an aryl group;^bIs at least one selected from a hydrogen atom, an optionally substituted alkyl group, a cycloalkyl group, an acyl group, an aralkyl group, an aryl group and an unsaturated aliphatic residue; n is a metal atom M^aAnd m is an integer in the range of 0 to 3. )
In the general formula (1), R^aIs a hydrogen atom and / or an optionally substituted alkyl group;^bIs preferably at least one selected from an optionally substituted alkyl group, cycloalkyl group, acyl group, aralkyl group, aryl group, and unsaturated aliphatic residue,R ^a Is more preferably at least one selected from a hydrogen atom, a methyl group and an ethyl group. Also, M^aIs preferably aluminum, zirconium, or silicon, and more preferably silicon, so that weather resistance is imparted.
[0026]
Degree of condensation in metal alkoxides and their derivatives such as (partially) hydrolyzed condensates (M in one molecule^a-O bond number) is preferably 1 to 1,000.
As the composition of the metal alkoxide, M^aIs a valence N, the molar ratio is M^a(OR^a)_N: M^a(OR^a)_N-1: M^a(OR^a)_N-2= 100: 0 to 10000: 0 to 1000 is preferred.
The method for producing the zinc oxide-based particles of the present invention is not particularly limited, but preferred examples include a production method described in detail below.
(Production method of zinc oxide particles)
The zinc compound used in the production method of the present invention has a structure represented by the following general formula (I). Since the zinc compound has this structure, the obtained zinc oxide-based particles have improved ultraviolet shielding properties and heat ray shielding properties.
[0027]
Zn (O)_k(OCOR)_x(OH)_y(OR ')_z      (I)
(However, R is at least one selected from a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group and an aralkyl group; R ′ is at least one selected from an alkyl group, a cycloalkyl group, an aryl group and an aralkyl group One kind; k, x, y and z satisfy k = (2-xyz) / 2, x + y + z ≦ 2, 0 <x ≦ 2, 0 ≦ y <2, and 0 ≦ z <2. )
As R and R 'in the general formula (I), an alkyl group having 1 to 4 carbon atoms such as a methyl group is preferable, a methyl group is more preferable, and zinc oxide particles having high dispersibility can be easily obtained.
[0028]
In the general formula (I), x preferably satisfies 1 ≦ x ≦ 2, y preferably satisfies 0 ≦ y <1, and z preferably satisfies 1 ≦ z <1. Zinc oxide-based particles having high properties are easily obtained.
The zinc compound preferably has a high dissolution rate, and particles having excellent dispersibility can be obtained. The dissolution rate is the time t until 2 parts of the zinc compound are mixed with 200 parts of ion-exchanged water (pH 5 to 8) at 25 ± 3 ° C. at 25 ° C. and completely dissolved to obtain a transparent solution. Defined. The dissolution rate of the zinc compound is preferably within 2 minutes, more preferably within 1 minute, and most preferably within 30 seconds.
[0029]
The hydrolyzed condensate of a zinc compound is a hydrolyzate and / or condensate obtained by hydrolyzing and / or condensing a zinc compound having a structure represented by the general formula (I). Up to the compound. The condensate is a metalloxane-bonded chain of zinc (Zn) and oxygen (O) — (Zn—O)_n(Where n is 1 or more). The degree of condensation of the condensate is not limited, and the degree of condensation (average) is preferably 100 or less, more preferably 10 or less, in order to obtain zinc oxide-based particles having a uniform crystallite size and shape. .
Metal elements used in the production method of the present invention (MThe compound of the formula (1) is not particularly limited, but preferably has a structure represented by the following general formula (II). Metal elements (MWhen the compound of (1) has this structure, the obtained zinc oxide-based particles have enhanced heat ray shielding properties.
[0030]
M(O)_{k '}(OCOR¹)_{x '}(OH)_{y '}(OR²)_{z '}      (II)
(However,MIs an m-valent (trivalent or tetravalent) metal; R¹Is at least one selected from a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group and an aralkyl group;²Is at least one selected from an alkyl group, an alkoxyalkyl group, a cycloalkyl group, an aryl group and an aralkyl group; k ′, x ′, y ′ and z ′ are k ′ = (mx′−y ′ -Z ′) / 2, x ′ + y ′ + z ′ ≦ m; when y ′ and z ′ may be 0, 0 <x ′ ≦ m, 0 ≦ y ′ <m, 0 ≦ z ′ <m; x When 'and z' may be 0, 0≤x '<m, 0 <y'≤m, 0≤z' <m; when x 'and y' may be 0, 0≤x '<m , 0 ≦ y ′ <m and 0 <z ′ ≦ m. )
In the general formula (II)MExamples of the element include the elements exemplified above, and among these, at least one selected from Al, Ga, and In is preferable, and the conductivity and the heat ray shielding property are enhanced. Two or more of them, including at least one of themMIn particular, when two of Al, Ga, and In are used in combination, the colorless transparency, the heat ray shielding property, and the conductivity are further enhanced as compared with the case of using each alone due to a synergistic effect.
[0031]
R in the general formula (II)¹Is preferably an alkyl group having 1 to 4 carbon atoms, and particularly preferably a methyl group. R²Is preferably an alkyl group or an alkoxyalkyl group having 1 to 4 carbon atoms. It is preferable that k '= 0, that is, x' + y '+ z' = m. In such a case, the metal element (M) Is contained in the zinc oxide crystal in a monomeric form,M, The effect of improving the conductivity and heat ray shielding properties can be obtained.
Metal elements (M) Is a hydrolyzate and / or condensate obtained by hydrolyzing and / or condensing a compound having a structure represented by the general formula (II), Up to the compound. The condensate is a metal element (M) And oxygen (O) are metalloxane-linked-(M-O)_n(Where n is 1 or more). The degree of condensation of the condensate is not limited, and the degree of condensation (average) is preferably 10 or less, more preferably 2 or less, in order to obtain zinc oxide-based particles having excellent conductivity and heat ray shielding properties.
[0032]
The alcohol used in the production method of the present invention is not particularly limited. For example, aliphatic monohydric alcohols (methanol, ethanol, isopropyl alcohol, n-butanol, t-butyl alcohol, stearyl alcohol, etc.), and aliphatic alcohols Saturated monohydric alcohol (allyl alcohol, crotyl alcohol, propargyl alcohol, etc.), alicyclic monohydric alcohol (cyclopentanol, cyclohexanol, etc.), aromatic monohydric alcohol (benzyl alcohol, cinnamyl alcohol, methyl phenyl carbyl) And monohydric alcohols such as heterocyclic monohydric alcohols (furfuryl alcohol and the like); alkylene glycols (ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,5-pentanediodiol) , 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, pinacol, diethylene glycol, triethylene glycol, etc.), aliphatic glycols having an aromatic ring (hydrobenzoin, benzpinacol, phthalyl) Alcohols), alicyclic glycols (cyclopentane-1,2-diol, cyclohexane-1,2-diol, cyclohexane-1,4-diol, etc.), polyoxyalkylene glycols (polyethylene glycol, polypropylene glycol, etc.), etc. Glycols: propylene glycol monoethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, 3-methyl-3-methoxybutanol , Ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, triethylene glycol monomethyl ether, derivatives of the above glycols such as ethylene glycol monoacetate such as monoethers and monoesters; hydroquinone, resorcinol, 2,2-bis (4-hydroxy Aromatic diols such as phenyl) propane and monoethers and monoesters thereof; trihydric alcohols such as glycerin and monoethers, monoesters, diethers and diesters thereof; used. As the alcohol, those having a boiling point under normal pressure of more than 100 ° C. are preferable.
[0033]
In the production method of the present invention, first, a zinc compound and / or a hydrolytic condensate thereof (hereinafter, sometimes simply referred to as a zinc-based compound) and a metal element (M) And / or a hydrolytic condensate thereof (hereinafter simply referred to asMIt may be called a system compound. ) And an alcohol to prepare a solution. Here, a zinc compound or a zinc compoundMThe mixture with the system compound may be in a completely dissolved state in the solution, or in a suspended or emulsified state. In order to improve the dispersibility of the resulting zinc oxide-based particles, before the particles are precipitated, the solution is heated to a zinc-based compound, or a zinc-based compound.MIt is preferable that the mixture with the system compound is completely dissolved.
[0034]
With zinc compoundsMThe system compound may be mixed with the alcohol at the same time or separately with the alcohol. In addition, a zinc-based compoundMThe composition may be mixed with the alcohol before preparing the composition mixed with the system compound. Preferably, the zinc-based compound is mixed with heated alcohol, in which case the alcohol isMIt may or may not contain a system compound.
The above solution isMIn systemic compoundsMIs adjusted to be 0.1 to 20 atomic% with respect to Zn in the zinc-based compound.MIs less than 0.1 atomic% with respect to Zn, the heat ray shielding property becomes insufficient. On the other hand,MIs more than 20 atomic% with respect to Zn, it is difficult to form particles having high uniformity in composition, crystal size, and the like, and the ultraviolet shielding property is reduced.
[0035]
The amount of the alcohol is not particularly limited, but is preferably 1 to 30 times, more preferably 5 to 25 times the molar ratio of the zinc compound to the zinc atom.
With zinc-based compoundsMWhen mixing the alcohol with the system compound, the alcohol is heated under normal pressure or under pressure, and the temperature is preferably 100 to 250 ° C, more preferably 120 to 200 ° C, and most preferably 150 to 200 ° C. . When alcohol is heated, zinc compounds andMThe conversion reaction rate from the system compound to the zinc oxide system particles is increased, so that secondary aggregation is suppressed, and particles having a uniform crystallite diameter can be obtained with high productivity. Further, after mixing the zinc-based compound with the alcohol, the temperature until the particles are formed, preferably 100 ° C. or more, more preferably 120 ° C. or more, most preferably 150 ° C. or more, the same as above Preferred for reasons. Here, when the zinc-based compound is mixed with the heated alcohol, the temperature of the alcohol is reduced by the sensible heat effect. As a method of suppression, it is preferable to previously heat the zinc-based compound or a solution containing the zinc-based compound, and the heating temperature is preferably 50 to 100 ° C. May be.
[0036]
The above solution is a monovalent or divalent metal elementM 'Is preferable, and the atomic ratio to zinc is more preferably in the range of 0.01 to 0.2%. Monovalent or divalent metal elementM 'Examples thereof include the above-mentioned ones, and similarly to the above, an alkali metal element and / or an alkaline earth metal element are preferable, and an alkaline earth metal element is more preferable.
Metal elementM 'Before the zinc oxide-based particles precipitate, especially with zinc-based compoundsMAlcohol before mixing the alcohol compound and the alcohol, zinc compound andMIt is preferable to contain it in any of the system compounds. In addition, zinc compounds and / orMIt may be compounded in the system compound. Metal elementM 'Is preferably added as its acetate.
[0037]
The solution is a zinc-based compound,MA compound containing components such as a carboxyl group-containing compound other than the system compound and the alcohol may be used.
Examples of the carboxyl group-containing compound include compounds having only one carboxyl group in the molecule such as a monocarboxylic acid compound. Specific examples of monocarboxylic acid compounds include saturated fatty acids (saturated monocarboxylic acids) such as formic acid, acetic acid, propionic acid, isobutyric acid, caproic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, and stearic acid; Unsaturated fatty acids (unsaturated monocarboxylic acids) such as methacrylic acid, crotonic acid, oleic acid, and linolenic acid; cyclic saturated monocarboxylic acids such as cyclohexanecarboxylic acid; aromatic monocarboxylic acids such as benzoic acid, phenylacetic acid, and toluic acid Carboxylic acid; anhydrides of the above monocarboxylic acids such as acetic anhydride; halogen-containing monocarboxylic acids such as trifluoroacetic acid, monochloroacetic acid and o-chlorobenzoic acid; compounds such as lactic acid; Used above. Preferred monocarboxylic acid compounds are saturated fatty acids having a boiling point of 200 ° C. or less at 1 atm, and saturated fatty acids having 1 to 20 carbon atoms. Specifically, formic acid, acetic acid, propionic acid, butyric acid, and isobutyric acid are preferable in that particles having excellent monodispersity can be easily obtained. This saturated fatty acid is preferably used in a range of 60 to 100 mol%, more preferably in a range of 80 to 100 mol%, based on the total amount of the monocarboxylic acid compound. If it is less than the above range, the crystallinity of the zinc oxide-based particles obtained may be low.
[0038]
The carboxyl group-containing compound is obtained by adding a zinc-based compound andMWhen a zinc oxide-based particle is produced by blending a system-based compound and heating the solution as it is, it may be dissolved in alcohol, and the zinc-based compound andMIt may be added to a system compound. Also, the solution may be heated and mixed before, after or simultaneously with the generation of zinc oxide-based particles. The mixing ratio of the carboxyl group-containing compound contained in the solution is preferably 1 mol or less, more preferably 0.5 mol or less, in terms of molar ratio to zinc, in order to enhance the dispersibility of the zinc oxide-based particles. Preferably it is 0.01 to 0.3 mol or less.
[0039]
The total content of impurities H in the solution is 0.5% or less in terms of the number of atoms with respect to zinc (however, calculated as the number of S atoms for sulfate groups and the number of N atoms for nitrate groups), When the content is more preferably 0.1% or less, further 0.01% or less, particularly 0.001% or less, zinc oxide-based particles having a small amount of impurities H can be easily obtained. The solution may not contain any impurity H.
In the production method of the present invention, the solution is prepared so that the water content thereof is 4 or less in molar ratio with respect to Zn, preferably 2 or less, more preferably 1 or less. Done. If the above molar ratio is more than 4, the resulting zinc oxide-based particles will have reduced ultraviolet ray shielding properties and heat ray shielding properties, as well as reduced dispersibility and reduced colorless transparency. The lower limit of the water content of the solution is higher when the water content is 0.01 or more in molar ratio to Zn than when the solution is completely anhydrous.
[0040]
In the production method of the present invention, zinc oxide-based particles can be precipitated by heating the solution to a reaction temperature of 100 ° C. or higher. When the reaction temperature is less than 100 ° C., the obtained zinc oxide-based particles have reduced ultraviolet ray shielding properties and heat ray shielding properties, and also have low dispersibility and low colorless transparency.
In the production method according to the present invention, it is preferable that the particles after the precipitation are subjected to a surface treatment with a surface treating agent for the purpose of reducing the photocatalytic activity of zinc oxide and imparting weather resistance. Examples of the surface treatment agent include those described above. The surface treatment is performed, for example, by adding the surface treatment agent to a reaction solution precipitated by heating.
[0041]
ADVANTAGE OF THE INVENTION According to the manufacturing method concerning this invention, the zinc oxide type particle excellent in ultraviolet-ray shielding property and heat ray shielding property can be manufactured simply and with good reproducibility. Furthermore, since zinc oxide-based particles can be obtained in the liquid phase, the growth of the primary particles and the secondary aggregation are suppressed compared with the conventional production method in which high-temperature sintering is performed. Even with the same specific surface area diameter, colorless transparency is excellent.
(Zinc oxide-based particle-containing composition)
The zinc oxide-based particle-containing composition according to the present invention is a composition containing the above-described zinc oxide-based particles and a binder component. Since this composition contains the zinc oxide-based particles according to the present invention, the composition has excellent ultraviolet ray shielding properties and heat ray shielding properties, and has high dispersibility and transparency.
[0042]
The zinc oxide-based particle-containing composition according to the present invention is used as a coating composition or a composition for a molding material. Hereinafter, the coating composition and the composition for a molding material will be described in detail in this order.
Paint composition
The zinc oxide-based particle-containing composition of the present invention can be used as a coating composition. Since the coating composition contains the zinc oxide-based particles of the present invention, the coating composition is excellent in ultraviolet ray shielding properties and heat ray shielding properties, and can provide a coating film having high dispersibility, transparency, colorlessness, and flexibility. Further, when the zinc oxide-based particles are subjected to a surface treatment, a coating film having higher weather resistance can be obtained.
[0043]
Examples of the binder component used in the coating composition include thermoplastic or thermosetting (including thermosetting, ultraviolet curable, electron beam curable, moisture curable, and combinations thereof) and various kinds of synthetic resins and natural resins. Organic binders and inorganic binders.
Examples of the synthetic resin include alkyd resin, amino resin, vinyl resin, acrylic resin, epoxy resin, polyamide resin, polyurethane resin, thermosetting unsaturated polyester resin, phenol resin, chlorinated polyolefin resin, silicone resin, and acrylic silicone resin. , A fluororesin, a xylene resin, a petroleum resin, a ketone resin, a rosin-modified maleic resin, a liquid polybutadiene, a coumarone resin, and the like, and one or more of these are used. Examples of the natural resin include shellac, rosin (pine resin), ester gum, cured rosin, bleached shellac, white shellac, and the like, and one or more of these are used.
[0044]
As the synthetic resin, a natural or synthetic rubber such as ethylene-propylene copolymer rubber, polybutadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene copolymer rubber, or the like may be used. Examples of components used in combination with the synthetic resin include cellulose nitrate, cellulose acetate butyrate, cellulose acetate, ethyl cellulose, hydroxypropylmethyl cellulose, and hydroxyethyl cellulose.
The form of the binder component used in the coating composition is not particularly limited, and examples thereof include a solvent-soluble type, a water-soluble type, an emulsion type, and a dispersion type (any solvent such as water / organic solvent).
[0045]
Examples of the water-soluble binder component include a water-soluble alkyd resin, a water-soluble acryl-modified alkyd resin, a water-soluble oil-free alkyd resin (water-soluble polyester resin), a water-soluble acrylic resin, a water-soluble epoxy ester resin, and a water-soluble melamine. Resins and the like can be mentioned.
Examples of the emulsion-type binder component include alkyl (meth) acrylate copolymer dispersion; vinyl acetate resin emulsion, vinyl acetate copolymer resin emulsion, ethylene-vinyl acetate copolymer resin emulsion, and acrylate (co) polymer resin. Emulsions, styrene-acrylate (co) polymer resin emulsions, epoxy resin emulsions, urethane resin emulsions, acryl-silicone emulsions, fluororesin emulsions, and the like can be given.
[0046]
Examples of the inorganic binder include metal alkoxides such as silica gel, alkali silicic acid, and silicon alkoxide, condensates (hydrolysis) thereof, and phosphates.
When the coating composition is used for the production of an ultraviolet absorbing film described below, for example, the film forming conditions such as the film forming temperature, and the viewpoint of the flexibility and weather resistance of the obtained film, the binder component used in the coating composition. For example, a polyurethane resin, an acrylic resin, a fluororesin, or the like is preferable.
The proportion of the zinc oxide-based particles in the coating composition is from 0.1 to 99% by weight, and preferably from 10 to 90% by weight, based on the total solid content of the zinc oxide-based particles and the binder component. When the proportion of the zinc oxide-based particles is less than 0.1% by weight, the ultraviolet ray shielding property and the heat ray shielding property are reduced. On the other hand, when the proportion of the zinc oxide-based particles exceeds 90% by weight, the transparency and the flexibility are reduced. When the zinc oxide-based particles contained in the coating composition are conductive, and the coating film obtained from the coating composition is used as a functional film such as a conductive film or an antistatic film, the zinc oxide-based particles in the coating composition may be used. The ratio is more preferably 50 to 90% by weight, and most preferably 70 to 85% by weight, based on the total solid content of the zinc oxide-based particles and the binder component.
[0047]
The coating composition contains zinc oxide-based particles and a binder component as essential components, and in addition to these, according to required performance, a curing agent such as a crosslinking agent; a curing catalyst such as a curing aid; a plasticizer; an antifoaming agent / leveling agent. Thixotropic agents; Matting agents; Surfactants; Flame retardants; Pigment wetting agents / dispersants; Lubricants; UV absorbers; Light stabilizers; Antioxidants; Other (heat) stabilizers; An anti-algal agent; an anti-corrosion / rust inhibitor; a dye;
When the coating composition is used for producing a film containing zinc oxide particles, weather resistance is improved if the coating composition contains a light stabilizer. When the coating composition contains a polyisocyanate as a curing agent, the versatility is high. Regarding the method of curing the coating composition when producing a film, the heat curing method is economically preferable.
[0048]
The coating composition may contain a solvent, and is appropriately selected depending on the purpose of use of the coating composition and the type of the binder component. Examples of the solvent include organic solvents such as alcohols, aliphatic and aromatic carboxylic esters, ketones, ethers, ether esters, aliphatic and aromatic hydrocarbons, and halogenated hydrocarbons; Mineral oil; vegetable oils, wax oils, silicone oils and the like, and one or more of these are used.
As a method for producing a coating composition, for example, a method of adding a zinc oxide-based particle to an organic solvent to form a slurry, and then mixing a binder component with the slurry containing the zinc oxide-based particle to produce a coating composition, etc. Can be mentioned.
[0049]
The coating composition can be applied to a surface of a base material described later such as an inorganic substance such as glass and ceramics, and an organic substance such as a resin.
Composition for molding material
The composition containing zinc oxide particles of the present invention can be used as a composition for a molding material. Since the composition for a molding material contains the zinc oxide-based particles of the present invention, it is excellent in ultraviolet ray shielding property and heat ray shielding property, and a molded article having high dispersibility, transparency, weather resistance and flexibility can be obtained. .
As the binder component used in the composition for a molding material, polyamide (6-nylon, 66-nylon, 12-nylon, etc.), polyimide, polyurethane, polyolefin (polyethylene, polypropylene, etc.), polyester (PET, PBT, PEN, etc.) ), Thermoplastic resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polystyrene, (meth) acrylic resin, ABS resin, silicone resin, fluororesin and monomers used as raw materials; Thermosetting resins such as formalin resins, cresol / formalin resins), epoxy resins, amino resins (urea resins, melamine resins, guanamine resins, etc.) and monomers used as raw materials for these resins. One or two or more are used.
[0050]
Examples of the binder component used in the molding material composition include soft resins or hard resins such as polyvinyl butyral, polyurethane, ethylene-vinyl acetate copolymer, and ethylene- (meth) acrylate copolymer. And one or more of these are used.
As the binder component used in the composition for a molding material, the above-mentioned inorganic binder component may be used.
The proportion of the zinc oxide-based particles in the molding material composition is from 0.1 to 99% by weight, preferably from 0.3 to 10% by weight, based on the total solid content of the zinc oxide-based particles and the binder component. is there. When the proportion of the zinc oxide-based particles is less than 0.1% by weight, the ultraviolet ray shielding property and the heat ray shielding property are reduced. On the other hand, when the proportion of the zinc oxide-based particles exceeds 99% by weight, strength, transparency and flexibility are reduced.
[0051]
The composition for a molding material contains zinc oxide-based particles and a binder component as essential components, and in addition to these, according to required performance, a curing agent, a curing accelerator, a coloring agent, a release agent, a coupling agent, a silicone compound, a reaction compound. It may contain additives such as a water-soluble diluent, a plasticizer, a stabilizer, a flame-retardant aid, and a crosslinking agent.
A curing agent may be required when using a thermosetting resin as a binder component. For example, when an epoxy resin is used as a binder component, polyamides, aliphatic polyamines, cycloaliphatic polyamines, aromatic polyamines or partially modified amines, acid anhydrides, dicyandiamides, imidazole , Amine imides, hydrazides, phenol novolaks, novolak-based curing agents such as cresol novolak, and the like, and one or more of these are used. When a phenol resin is used as the binder component, urotropin, formal, and the like can be used, and one or more of these are used. These amounts are used in appropriate amounts with respect to the binder component.
[0052]
The plasticizer is for further improving the processability of the composition, and includes, for example, phosphates, phthalates, aliphatic or dibasic esters, dihydric alcohol esters, oxyacid esters. And polyglycols. Particularly, when an epoxy resin is used as a binder component, polyglycols are preferable.
The stabilizer suppresses decomposition of the binder component, and examples thereof include lead stearate and zinc stearate.
Examples of the flame retardant aid include organic phosphorus compounds such as phosphates, phosphites, acid phosphates, and phosphonium salts. These additives can be used in appropriate amounts.
[0053]
Examples of the method for producing the molding material composition include a method of uniformly mixing the zinc oxide-based particles and the binder component using a mixing device such as a roll, a kneader, and a mixer.
Examples of the method of molding the composition for a molding material include extrusion molding, injection molding, casting, compression molding, low-pressure transfer molding, and cast molding.
The composition for a molding material may be formed into a film, for example, and the obtained film is excellent in ultraviolet shielding property, transparency, heat ray shielding property and the like.
[0054]
A laminated glass can be obtained by sandwiching a zinc oxide-based particle-containing sheet obtained by molding the composition for a molding material with a transparent plate such as a glass plate and curing it appropriately. The thickness of the zinc oxide-based particle-containing sheet is preferably 0.1 to 2 mm, more preferably 0.5 to 1 mm.
〔Painted〕
The coated product according to the present invention (hereinafter, sometimes referred to as coated product A) is obtained by forming a coating film obtained from the coating composition (composition containing zinc oxide particles) on the surface of a substrate. . The coated article A has excellent transparency, ultraviolet ray shielding property, heat ray shielding property, etc., because it has a coating film obtained from the coating composition on its surface. This coating film is useful for an ultraviolet shielding film, a heat ray shielding film, an antistatic film, a photocatalytic film, an infrared radiation film, a thermoelectric conversion film and the like.
[0055]
Examples of the substrate include, for example, inorganic materials such as glass and ceramics, and substrates such as organic materials such as resins, and in particular, a coating film obtained by applying a coating composition to the surface of an organic substrate, High weather resistance and excellent flexibility. The shape of the inorganic or organic material is not particularly limited, and examples thereof include a film shape, a sheet shape, a plate shape, and a fiber shape. Among these, it is useful for films, fibers and the like.
There is no particular limitation on the material of the resin used as the base material. For example, LDPE, HDPE, amorphous polyethylene, OPP (stretched polypropylene), polypropylene such as CPP (crystallized polypropylene), and polyolefins such as polyisobutylene; EVA ( Ethylene-vinyl acetate copolymer); polystyrene; soft or hard polyvinyl chloride; EVOH (ethylene-vinyl alcohol copolymer); PVA (vinylon); PVDC (polyvinylidene chloride); polyethylene terephthalate; Polyesters such as polyethylene naphthalate and polybutylene naphthalate; polycarbonates; polyurethanes; polyamides; polyimides; polyacrylonitriles; polysulfones; Polysulfide, polyarylate, polyetherimide, aramid, (meth) acrylic, polyetheretherketone, tetrafluoroethylene / ethylene copolymer, tetrafluoroethylene / hexafluoropropylene copolymer, polytetra Fluoroethylene, polytrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, polyvinyl fluoride, tetrafluoroethylene / hexafluoropropylene / perfluoroalkyl vinyl ether copolymer, polychlorotrifluoro A fluorine-based resin such as ethylene can be used.
[0056]
When used in applications requiring extremely high visible light transmittance and transparency, such as optical lenses, PMMA, MMA-styrene random copolymer, polycarbonate, transparent polypropylene, MMA and α-methylstyrene or cyclohexyl methacrylate, etc. , ABS resin MMA modified type, polystyrene, polyarylate, polysulfone, polyethersulfone, transparent epoxy resin, poly-4-methylpentene-1, fluorinated polyimide, amorphous fluororesin, transparent phenoxy resin Various resins such as an amorphous nylon resin and a fluorene-based resin can be used as the base material.
[0057]
In addition, due to the problem of disposal, it is increasingly important to use a biodegradable resin as a base material in order to meet the demand for biodegradability. In such a case, for example, poly-3-hydroxybutyrate, chitin / chitosan, polyamino acid, cellulose, polycaprolactone, alginic acid, polyvinyl alcohol, aliphatic polyester, saccharide, polyurethane, polyurethane It is preferable to use an ether-based biodegradable plastic or the like as a base material.
As the substrate, a substrate in which an ultraviolet absorbing film is disposed in advance on the above substrate, or a substrate in which a primer layer or the like is disposed in advance for the purpose of enhancing the adhesion between the coating film obtained from the coating composition and the substrate, etc. Good.
[0058]
Among these resins used as the base material, among plastic films and sheets, fluorine-based resins, polyester-based resins, (meth) acrylic-based resins, and polycarbonate-based resins are preferable because of their high weather resistance.
The coated article A can be manufactured, for example, by applying a coating composition on the surface of the base material and curing the coating composition.
The method of applying the coating composition to the substrate surface is not particularly limited, and includes a dipping method, a roll coater method, a flow coat method, a screen printing method, a bar coater method, a spin coater method, a brush coating method, a spray method, and the like. Can be mentioned.
[0059]
After the coating composition is applied, heat curing (including room temperature curing), moisture curing, and ultraviolet light are performed to improve physical properties such as water resistance, solvent resistance, acid resistance, alkali resistance and other chemical resistance, and abrasion resistance. It is preferable to cure by a method such as curing and electron beam curing.
The dry film thickness of the coating film obtained from the coating composition is not particularly limited, and is preferably from 0.1 to 50 μm. When this coating is used for the purpose of shielding ultraviolet rays, the dried film thickness of the coating is more preferably 0.5 to 30 μm, and most preferably 1 to 10 μm. In this case, the dried film thickness of the coating film is more preferably 1 to 20 μm, most preferably 2 to 15 μm. The film thickness is more preferably from 0.2 to 5 μm, most preferably from 0.5 to 2 μm.
[0060]
After coating and forming a coating composition, heat curing (including room temperature curing), moisture curing, and ultraviolet curing, from the viewpoint of chemical resistance such as water resistance, solvent resistance, acid resistance, and alkali resistance, and abrasion resistance. It is preferable to form a cured film by a curing method such as electron beam curing.
In order to impart a sufficient heat ray shielding property to the coated product A, the coating film contains 5 to 15 g / m 2 of zinc oxide-based particles.²It is preferable to apply the coating composition to the substrate such that
The surface resistance ρ of the coating film obtained from the coating composition is not particularly limited, but is preferably 10 when it is desired to impart antistatic / antistatic properties or stain resistance.¹¹Ω or less, more preferably 10⁹Ω or less.
[0061]
The haze of the coating film obtained from the coating composition is not particularly limited, but is preferably 3% or less, more preferably 1% or less, and most preferably 0.5% or less. Haze is a value obtained by measuring with a turbidimeter.
A laminated glass can be obtained using a coated transparent plate having an intermediate film formed by applying the coating composition to a transparent plate such as a glass plate. This laminated glass can be manufactured by stacking an adhesive sheet so as to be sandwiched between a coated transparent plate and a separately prepared transparent plate. The interlayer of the coated transparent plate and the adhesive sheet are overlapped.
Examples of the adhesive sheet include a sheet made of a soft resin or a hard resin such as a polyvinyl butyral resin, a polyurethane resin, an ethylene-vinyl acetate copolymer resin, and an ethylene- (meth) acrylate copolymer resin. And a soft resin is preferred. The thickness of the adhesive sheet is preferably 0.1 to 2 mm, more preferably 0.5 to 1 mm.
[0062]
When a film is used as a substrate, the obtained coated product A is a film containing zinc oxide particles. The thickness of the substrate film is not particularly limited, and is preferably 5 to 500 µm, more preferably 10 to 200 µm.
The method for applying the coating composition on the surface of the base film, the dry film thickness, and the like are not particularly limited, and those described above are preferable.
The zinc oxide-based particle-containing film is not particularly limited as long as the coating film obtained from the coating composition is formed on the substrate film, and may be further processed according to the application, required characteristics, and the like. The film containing the zinc oxide particles is coated on the surface of the coating film not in contact with the base film and / or the surface of the base film not in contact with the coating film with an adhesive layer or a protective layer (a hard coat for imparting scratch resistance). Film) or a laminated film laminated with another film.
[0063]
The ultraviolet transmittance of the film containing zinc oxide particles is not particularly limited, but is preferably 50% or less, more preferably 10% or less. The ultraviolet transmittance is a value obtained by an apparatus and a measuring method described in JIS R 3106.
The visible light transmittance of the film containing zinc oxide particles is not particularly limited, but is preferably 70% or more, and more preferably 80% or more. The visible light transmittance is a value measured in a wavelength range of 380 to 780 nm and obtained by an apparatus, a measuring method, and a calculating method described in JIS R 3106.
The haze of the film containing zinc oxide particles is not particularly limited, but is preferably 10% or less, more preferably 5% or less, and most preferably 3% or less. Haze is a value obtained by measuring with a turbidimeter.
[0064]
The weather resistance of the zinc oxide-based particle-containing film was determined by performing an accelerated weather resistance test using a cyshine carbon arc lamp-type light resistance and weather resistance tester described in JIS B 7753-93. When the haze value and the hue after the 240-hour test are further compared with each other based on the value and the hue, the change in haze is preferably less than 2%, and more preferably no change in color (discoloration).
Another coated article according to the present invention (hereinafter, sometimes referred to as coated article B) is a liquid containing zinc oxide-based particles and a solvent (the dispersion containing the above-described zinc oxide-based particles) is coated on the surface of the substrate. And a thin film is formed on the surface of the base material by coating and heating. The thin film consists of zinc oxide and metal elements (MThe coated product B has excellent ultraviolet shielding property and heat ray shielding property, and the thin film has high weather resistance and high colorless transparency because the oxide of (1) is an essential component. This thin film is useful as an ultraviolet shielding film, a heat ray shielding film, an electromagnetic shielding film, a conductive film of a transparent electrode, an antistatic film, a photocatalytic film, an infrared radiation film, a thermoelectric conversion film and the like.
[0065]
The dispersion used in the coated product B may contain a binder component that is converted into a metal oxide by thermal decomposition or the like when heated. There is no particular limitation on the amount of the binder component, but high conductivity due to the contact between the zinc oxide-based particles, electromagnetic shielding properties, and thermal shielding properties due to the formation of a polycrystalline film or a single crystal film, etc. In order to obtain a functional film, it is preferable that the particle concentration is high, and the amount is preferably less than 25% by volume with respect to the thin film when the binder component is converted into metal oxide. When the binder component is not substantially left in the obtained thin film due to thermal decomposition or combustion by heating of the organic binder or the like, the blending ratio of the binder component in the dispersion is not particularly limited, but the remaining binder component In order to form a thin film that is less likely to be colored by an object or the like and has excellent functionality, the content is preferably 25% by volume or less.
[0066]
The heating temperature at the time of the heating is not particularly limited, but is preferably 300 to 1600 ° C, more preferably 400 to 1000 ° C. If the heating temperature is lower than 300 ° C., a thin film may not be easily formed. On the other hand, if the heating temperature exceeds 1600 ° C., it becomes impractical. In some cases, heating is preferably performed in an oxidizing gas atmosphere such as in air to promote thermal decomposition and combustion, but ultimately, in an inert gas atmosphere such as nitrogen or a reducing gas such as hydrogen. It is preferably performed under an atmosphere or under vacuum.
The thickness of the thin film is not particularly limited, but is preferably 0.1 to 10 μm, more preferably 0.5 to 4 μm, and most preferably 1 to 2 μm.
[0067]
The ultraviolet shielding properties of the coated products A and B are not particularly limited, and the wavelength λa at which the spectral transmittance becomes 2% is preferably 365 nm or more, more preferably 368 nm or more, and most preferably 370 nm or more.
The heat ray shielding properties of the coated products A and B are not particularly limited, and the calculation method described in 4.4 of JIS R3106-1985 (the coefficient Dλ · Vλ is the value shown in Appendix Table 2), and the heat ray transmittance (TIR) obtained according to the exemplified formula is preferably less than 80%, more preferably less than 65%, and most preferably less than 45%. is there.
[0068]
In the coated products A and B, the zinc oxide-based particles of the present invention are used, so that even with a small amount of application, the coating products are higher than the coated products described in Japanese Patent Application Nos. 9-124550 and 9-1491108. Ultraviolet ray shielding property and heat ray shielding property are obtained.
[0069]
【Example】
Hereinafter, Examples of the present invention are shown together with Comparative Examples, but the present invention is not limited to the following Examples. Note that “%” means “% by weight” and “parts” means “parts by weight”.
Evaluation and the like in this example were performed by the following method.
1. Evaluation of zinc oxide particles
<Powder sample preparation method>
After the fine particles in the obtained dispersion are separated by a centrifugal separation operation, washing with methanol and washing with acetone are sufficiently performed, followed by vacuum drying at 30 ° C. for 1 day and further vacuum drying at 80 ° C. for 1 day. The volatile components were completely removed to obtain fine particle powder, which was used as a powder sample.
<Carboxylic acid (residual) group content (acetoxy group content)>
1 g of the powder sample was mixed with a 0.01 N aqueous sodium hydroxide solution, stirred for 3 days, and then the supernatant obtained by centrifugation was measured by ion chromatography.
<Crystallinity>
It was evaluated by powder X-ray diffraction.
<Crystallite diameter Ds (hkl), Dw>
The powder sample was measured by powder X-ray diffraction measurement.
[0070]
Ds (hkl):ScherrerLaw (Cauchy(By function approximation), the crystallite diameter in the direction perpendicular to each of the obtained diffraction planes (hkl)
Dw:WilsonOf crystallites and lattice strain obtained by using the method
<Amount of impurity H>
The content of halogen elements other than F was determined by X-ray fluorescence analysis of the powder sample, and the content of nitrate and sulfate was determined by ion chromatography in the same manner as the analysis of the content of acetoxy group.
<UV shielding>
Diffuse reflectance measurement is performed on the powdered sample, and the reflectance at 350 nm at which the reflectance becomes substantially 0% in the wavelength range of 300 to 400 nm is defined as R (350) (%), and the reflectance is [R (350). ) +2] (%) to the ultraviolet transmission end TI_uvAnd The diffuse reflectance measurement was performed using a self-recording spectrophotometer (UV-3100 manufactured by Shimadzu Corporation) in which an integrating sphere attachment device (ISR-3100 manufactured by Shimadzu Corporation) was attached to the sample chamber. The ultraviolet shielding property was evaluated according to the following evaluation criteria.
：: TI_uv≧ 374 nm
：: 370 nm ≦ TI_uv<374 nm
×: TI_uv<370 nm
<Heat shielding properties>
The reflectance at a wavelength of 1000 nm obtained by powder diffuse reflectance measurement is R (1000), and the maximum reflectance at a wavelength of 380 to 780 nm is R (λ)._max), R (NIR) = R (1000) / R (λ_max) Was calculated.
<Colorless>
The reflectance at a wavelength of 780 nm obtained by powder diffuse reflectance measurement is R (780), and the maximum reflectance at a wavelength of 380 to 780 nm is R (λ)._max), R (BL) = R (780) / R (λ_max) Was calculated.
<Monodispersity>
With respect to the dispersion obtained by the particle formation reaction, the number average particle diameter Ddn was determined by a dynamic light scattering method using the following measuring device and measuring method, and the following evaluation criteria were determined based on the ratio to Dw (r = Ddn / Dw). Was evaluated according to
[0071]
Measuring apparatus: DLS-700 dimic light diffuser manufactured by Otsuka Electronics Co., Ltd.
Measuring method: The dispersion was heated and concentrated under reduced pressure to a metal oxide (zinc oxide) concentration of 25% by weight, and a cake was obtained by a centrifugal separation operation. A cake containing 0.5 g of oxide (zinc oxide concentration of 50 to 70% by weight) %) Was weighed, mixed with 10 g of a toluene solution in which 0.15% by weight of the polyester polyamine was dissolved, stirred for 1 hour with a magnetic stirrer, and then measured. Upon measurement, toluene was used as a diluting solvent.
A: r <1.5
B: 1.5 ≦ r <3
C: 3 ≦ r <5
D: 5 ≦ r
<Particle concentration in dispersion>
A part of the dispersion was weighed in a crucible, vacuum-dried at a temperature 40 ° C. lower than the boiling point of the solvent for 24 hours, and then heated at 600 ° C. for 1 hour in the air to obtain an ash content.
<Powder resistance>
800 kg / cm²The measurement was carried out under the pressurized condition.
<Metal elementsMandM 'Content and Surface Treatment Agent Content>
It was determined by X-ray fluorescence analysis, atomic absorption analysis, plasma emission analysis, gravimetric analysis, and elemental analysis.
<Film transparency>
The dispersion containing the zinc oxide-based particles is concentrated to 20% by weight, and the obtained concentrate is mixed with an acrylic resin binder having the same weight as the particles in terms of solid content, stirred for 3 hours, and then, using a bar coater. It was applied on a transparent glass plate so as to have a dry film thickness of 5 μm, and dried at 100 ° C. to obtain a film-coated glass having a particle dispersion film on the surface. The haze of the film-coated glass was measured, and less than 1% haze was evaluated as ○, and more than 1% haze was evaluated as x.
2. Method for producing zinc oxide-based particles
<Water content>
A zinc (system) compound was mixed in methanol, and water released was measured by the Karl Fischer method. When water of crystallization exists and is not released at room temperature, the zinc (system) compound is suspended in ethylene glycol monomethyl ether acetate, and the suspension is heated at 120 ° C. for 1 hour, and the released water is measured. The sum of the water contained in the other raw materials and the water measured above was determined, and the molar ratio to Zn was calculated.
3. Evaluation of coated products and resin molded products obtained in Examples
<Spectral characteristics>
The ultraviolet shielding property and the visible light transmittance were evaluated by measuring the spectral transmittance for light having a wavelength in the range of 300 to 800 nm using the above-mentioned spectrophotometer (with an integrating sphere).
UV shielding
The wavelength λa at which the spectral transmittance was 2% was determined and evaluated according to the following evaluation criteria.
A: λa ≧ 370 nm
：: 365 nm ≦ λa <370 nm
×: λa <365 nm
Visible light transmission
According to the method described in JIS R 3106-1985, the visible light transmittance Tv was calculated using the transmittance and the weighting factor for light of each wavelength, and evaluated according to the following evaluation criteria.
：: Tv ≧ 80%
Δ: 70% ≦ Tv <80%
×: Tv <70%
Heat shielding
Applying the calculation method described in 4.4 of JIS R3106-1985 (coefficients Dλ and Vλ for each wavelength light use the values in Appendix Table 2) to the transmittance of light having a wavelength of 800 to 1800 nm according to the following equation , Heat ray transmittance (TIR) and evaluated according to the following evaluation criteria.
[0072]
(Equation 1)

[0073]
τ (λ): transmittance at 800 to 1800 nm
◎: TIR <45%
：: 45% ≦ TIR <65%
Δ: 65% ≦ TIR <80%
×: TIR ≧ 80%
<Transparency>
Haze (actually measured value) was measured with a turbidity meter (NDH-1001 DP manufactured by Nippon Denshoku Industries Co., Ltd.).
<Colorless>
The colorlessness was visually determined and evaluated according to the following evaluation criteria.
◎: No coloring
：: slight coloring, practically no problem
△: slightly colored
×: Conspicuous coloring
<Surface resistance>
A gold comb electrode was deposited on the surface of the coating film (thickness: 30 nm ± 5 nm), allowed to stand at a temperature of 25 ° C. and a relative humidity of 50% for 1 hour under light-shielding conditions, and then subjected to the same process using an electrometer 617 manufactured by Kesley. The surface resistance under the conditions was measured (applied voltage: 0.1 V).
<Weather resistance>
An accelerated weather resistance test was carried out using a cyshine carbon arc lamp type light resistance and weather resistance tester described in JIS B 7753-93. Based on the haze value and the hue after the initial 100 hours, the haze value and the hue after the 240-hour test were further compared and evaluated according to the following evaluation criteria.
A: Haze change is less than 2% and there is no coloring (discoloration).
B: Haze change is 2% or more and / or coloring (discoloration) occurs.
<Stain resistance>
The test piece was exposed outdoors for 10 days, and the degree of contamination on the surface (coating side) was relatively evaluated.
[0074]
-Example 1-1
Externally heatable 100 liter stainless steel (SUS316) reactor equipped with a stirrer, addition port, thermometer, distillate gas outlet and nitrogen gas inlet, and directly connected to the addition port via a ball valve. A reactor equipped with an addition tank, a condenser directly connected to a distillate gas outlet, and a distillate trap was charged with 2163 parts of benzyl alcohol, heated to 150 ° C., and mixed with 1.8 g of water. To this reactor, 500 parts of a benzyl alcohol slurry (Zn-added liquid) containing 202 parts of anhydrous zinc acetate powder (manufactured by Kanto Chemical Co., industrial) and 1.23 parts of aluminum sec-butoxide were added over 30 seconds from the addition tank. After mixing and raising the temperature to 200 ° C., the temperature was maintained for 1 hour to obtain 1017 parts of a particle dispersion. When the Zn-added liquid was mixed, the water content in the solution was 0.1 in molar ratio to Zn. When the bottom temperature of the heating process reached 170 ° C., 19 parts of a benzyl alcohol solution containing 30% by weight of caproic acid was added from the addition tank to the bottom over 1 minute.
[0075]
The obtained dispersion (d1) contained 8.0% by weight of zinc oxide-based particles (P1) having physical properties shown in Tables 3 and 4. Table 5 shows the physical properties and film transparency of the dispersion liquid (d1). Further, the solvent of the dispersion liquid (d1) was mainly benzyl alcohol, and further contained 21% by weight of benzyl acetate. The water content in the dispersion was less than 0.1% by weight.
-Comparative Example 1-1
The Zn-added liquid used in Example 1-1 was mixed with 220 parts of zinc acetate dihydrate powder, 1.23 parts of aluminum sec-butoxide, 41 parts of acetic acid, 54 parts of ion-exchanged water, and 183.77 parts of benzyl alcohol. The reaction was carried out in the same manner as in Example 1-1, except that the addition liquid was changed to 500 parts, to obtain a dispersion (cd1) having a particle concentration of 10% by weight. When the Zn-added liquid was mixed, the water content contained in the solution was 5.1 in molar ratio to Zn. The dispersion (cd1) contained the zinc oxide-based particles (CP1) having the physical properties shown in Tables 3 and 4. Table 5 shows the physical properties and film transparency of the dispersion liquid (cd1).
[0076]
-Example 1-2
The reaction was carried out in the same manner as in Example 1-1 except that indium acetate dihydrate (10.75 parts) was used instead of aluminum sec-butoxide (1.23 parts) in Example 1-1, and the particle concentration was 7. A 5% by weight dispersion (d2) was obtained. When the Zn-added liquid was mixed, the water content contained in the solution was 0.18 in molar ratio to Zn. The dispersion (d2) contained the zinc oxide-based particles (P2) having the physical properties shown in Tables 3 and 4. Table 5 shows the physical properties and film transparency of the dispersion liquid (d2).
-Comparative Example 1-2
The reaction was conducted in the same manner as in Comparative Example 1-1 except that indium acetate dihydrate (10.75 parts) was used instead of aluminum sec-butoxide (1.23 parts) in Comparative Example 1-1. A 7% by weight dispersion (cd2) was obtained. When the Zn-added liquid was mixed, the water content contained in the solution was 5.2 in molar ratio to Zn. The dispersion (cd2) contained the zinc oxide-based particles (CP2) having the physical properties shown in Tables 3 and 4. Table 5 shows the physical properties and film transparency of the dispersion liquid (cd2).
[0077]
-Examples 1-3 to 1-11-
Using the same reactor as in Example 1-1, a reaction was performed under the zinc compounds and temperature conditions shown in Tables 1 and 2, and the dispersions containing zinc oxide-based particles (P3) to (P11), respectively. Liquids (d3) to (d11) were obtained.
The physical properties of the zinc oxide-based particles (P3) to (P11) obtained above are shown in Tables 3 and 4, respectively. The dispersions (d3) to (d11) and their film transparency are shown in Table 5, respectively.
The zinc oxide particles (P7) to (P11) have been treated with the surface treatment agents shown in Table 2, and the surfaces thereof have been treated with a thin film of a photocatalytically inactive hydroxide monomer, oligomer or oxide. I have.
[0078]
[Table 1]

[0079]
[Table 2]

[0080]
(Notes for Tables 1 and 2)
* 1: Benzyl alcohol containing acetic acid aqueous solution
1. The anhydrous zinc acetate used as the zinc compound was used after pulverizing a commercial product. Its specific surface area is 13m²/ G.
2. The mixing method described above uses a zinc compound and a metal element (M) And an alcohol, and were performed by any of the following methods A to E.
A: After adding the zinc compound to the alcohol and before the zinc oxide-based particles precipitateMIs further added.
B: zinc compound andMThe mixture obtained by mixing the above compounds is added to alcohol.
C: In alcoholMIs dissolved, and a zinc compound is further added.
D: After the zinc compound is added to the alcohol and before the zinc oxide-based particles precipitate,MCompounds andM 'Compound (M 'Is added.
E: zinc compound,MCompounds andM 'Compound (M 'Is added to the alcohol.
[0081]
3. The surface treatment agent is dissolved in the same alcohol as the solvent, to a concentration of 50%.Preparation1 hour after the particles have precipitated.
4. The additive is a carboxyl group-containing compound, dissolved in the same alcohol as the solvent, to a concentration of 30%.Preparation5 minutes after the particles have precipitated. The addition amount is 5 mol% based on Zn.
5. When the addition form of the zinc compound was a suspension, a slurry having a zinc compound solid concentration of 40% by weight was used.
[0082]
[Table 3]

[0083]
[Table 4]

[0084]
The amount of the impurity H was less than 0.001 mol% with respect to Zn in all the particles.
[0085]
[Table 5]

[0086]
-Example 2-1
The dispersion (d1) obtained in Example 1-1 was centrifuged to obtain a cake having a particle concentration of 50% by weight. This cake was re-dispersed in toluene so as to have a particle concentration of 7% by weight, centrifuged again, and the obtained cake was dispersed again in toluene to obtain a toluene dispersion (DE1) having a particle concentration of 40% by weight. Was prepared.
-Examples 2-2 to 2-8 and Comparative examples 2-1 to 2-2
Using the dispersion and the solvent shown in Table 6, dispersions were prepared by the preparation methods shown in Table 6, respectively. In Example 2-8, a plasticizer was used as a solvent.
[0087]
[Table 6]

[0088]
-Example 3-1
An acrylic resin solution (B1) shown in Table 7 was added to the dispersion (DE1) as a binder resin, mixed, and dispersed using a sand mill. Further, isocyanurate-modified hexamethylene diisocyanate as a curing agent is added and mixed, and the mixture is stirred at 25 ° C. for 30 minutes to prepare a paint (1). The paint (1) is applied to a PET film, and is applied to a hot air drier. The coating was dried at 2 ° C. for 2 minutes to obtain a film-like coated product (1). Table 8 shows the results of the evaluation of the coated product (1).
-Examples 2-2 to 3-3 and Comparative examples 3-1 to 3-2-
In the same manner as in Example 3-1, paints (2) to (3) and paints comprising a binder resin shown in Table 7, each dispersion prepared in Example 2, and a curing agent and a curing catalyst as required. (C1) to (c2) were prepared, and in the same manner as in Example 3-1, film-like coated products (2) to (3) and coated products (c1) to (c2) were obtained. Table 8 shows the evaluation results of these coated products.
[0089]
[Table 7]

[0090]
[Table 8]

[0091]
(Note for Table 8)
1. Isocyanurate-modified hexamethylene diisocyanate was used as a curing agent, and was added in an amount equivalent to the amount of hydroxyl groups in the binder resin.
2. The solid content contained in each paint is 50% by weight.
3. After applying the coating materials, each was dried with hot air at 90 ° C. for 2 minutes.
From Table 8, the coated product (1) is superior to the coated product (c1) in ultraviolet shielding properties and transparency. The coated product (2) is superior to the coated product (c2) in ultraviolet shielding property, heat ray shielding property and transparency. The coated product (3) is excellent in ultraviolet ray shielding property, heat ray shielding property and transparency, and also excellent in weather resistance.
[0092]
In addition, as a result of evaluating the surface resistance of the coated products (1) to (3) on the coating film side, 10% was obtained for the coated product (1).^ThirteenΩ / □ order, anti-static level (10⁶-10⁹Ω / □ order), anti-static level (10¹⁰-10¹¹(Ω / □ order).
-Examples 3-4 to 3-5
In the same manner as in Example 3-1, a fluororesin solution (B3) shown in Table 7 was added to the dispersion (DE5) as a binder resin, mixed, and dispersed using a sand mill. Further, isocyanurate-modified hexamethylene diisocyanate as a curing agent is added and mixed, and the mixture is stirred at 25 ° C. for 30 minutes to prepare paints (4) to (5). The film was dried at 105 ° C. for 2 minutes in a drier to obtain film-like coated products (4) and (5). Table 9 shows the evaluation results of these coated products.
[0093]
-Comparative Example 3-3-
A coating material (c3) was prepared in the same manner as in Example 3-4 except that the dispersion (DE5) was not used, and a film-like coated product (c3) was obtained in the same manner as in Example 3-4. . Table 9 shows the evaluation results of these coated products.
The coated product (c3) was insulating, but the coated products (4) and (5) had antistatic properties and antistatic properties. The stain resistance decreased in the order of the coated product (4)> the coated product (5)> the coated product (c3).
-Example 3-6
The coating material (6) shown in Table 9 was prepared in the same manner as in Example 3-4, applied to a vinyl chloride film, and dried at 105 ° C. for 2 minutes with a hot air drier to obtain a film-like coating product (6). ) Got. Table 9 shows the evaluation results of these coated products.
[0094]
The coated product (6) had antistatic properties and improved stain resistance as compared with a vinyl chloride film having no coating film (Comparative Example 3-4).
[0095]
[Table 9]

[0096]
(Note for Table 9)
1. In Examples 3-4 to 3-5 and Comparative Example 3-3, isocyanurate-modified hexamethylene diisocyanate was used as a curing agent and added so as to be equivalent to the hydroxyl group amount of the binder resin.
2. The solid content concentration in each paint is 40% by weight.
3. The thickness of the substrate was 70 μm for the fluorine film and 100 μm for the vinyl chloride film.
4. After applying the coating materials, each was dried with hot air at 105 ° C. for 2 minutes.
[0097]
-Examples 3-7 to 3-9-
Coatings (7) to (9) shown in Table 10 were prepared in the same manner as in Example 3-4, applied to a substrate, and dried to obtain coated products (7) to (9). Table 10 shows the evaluation results of these coated products.
All of these coated articles were excellent in ultraviolet ray shielding property, heat ray shielding property, transparency and colorlessness.
[0098]
[Table 10]

[0099]
(Note for Table 10)
1. In Example 3-7, dibutyltin dilaurate was used as a curing catalyst, and in Example 3-9, a melamine resin was used as a curing agent.
2. The thickness of the substrate was 3 mm for a polycarbonate resin plate (PC plate) and 1.5 mm for a glass plate.
3. After application of the paint, in Example 3-7, 1) after 60 hours at room temperature, and 2) drying at 100 ° C. for 2 hours. In Example 3-8, 1) after 60 hours at room temperature, 2) drying at 100 ° C. for 2 hours, and 3) baking under nitrogen atmosphere at 300 ° C. for 1 hour. In Example 3-9, baking was performed at 180 ° C. for 20 minutes.
[0100]
-Example 3-10-
21 parts of the dispersion (DP11) obtained in Example 2-8 was mixed with 20 parts of dioctyl phthalate, and this mixture was mixed and kneaded with 100 parts of a polyvinyl butyral resin to contain 1.5% by weight of particles dispersed therein. The obtained resin composition was obtained. This resin composition was molded with an extrusion molding machine to obtain a polyvinyl butyral sheet having a thickness of 0.8 mm.
This sheet is sandwiched between 3 mm-thick glass sheets, kept at 100 ° C. for 1 hour under reduced pressure, then cooled to room temperature and then placed in an autoclave, and the pressure is set to 8 kg / cm.²At a temperature of 130 ± 7 ° C. for 30 minutes to obtain a laminated glass.
[0101]
This laminated glass was an ultraviolet-shielding transparent laminated glass, and the ultraviolet-shielding property was ◎, the visible light transmittance was ◎, and the transparency was 0.3% haze.
-Example 3-11-
Tetraethoxysilane was added to the dispersion (DE6) obtained in Example 2-4, and zinc oxide-based particles / SiO₂= 95/5 (weight ratio), and a coating solution having a total solid content of 20% by weight was prepared. This coating solution is applied in advance to a glass plate on which a silica film has been formed, dried at 100 ° C., and then heat-treated at 600 ° C. for 1 hour in a nitrogen atmosphere to form a glass plate on which an oxide film has been formed. Got.
[0102]
This glass plate has a thickness of 1.6 μm and a surface resistance of 4 × 10⁸Ω / □, ultraviolet ray shielding line was 線, heat ray shielding property was ◎, transparency was 0.1% or less of haze, and colorlessness was ◎.
-Example 3-12-
A coating material was prepared by mixing the aqueous dispersion (DE9) obtained in Example 2-5 with an acrylic resin emulsion. The concentration of the particles in the solid content contained in the paint was 20% by weight. A nylon fiber is immersed in this paint and dried to obtain a particle weight of 3 g / m.²Fiber was obtained. This fiber was excellent in antistatic properties and weather resistance.
[0103]
-Example 3-13-
The dispersion (d4) obtained in Example 1-4 was concentrated under reduced pressure using an evaporator, further dried, and vacuum-dried at 80 ° C to obtain a particle powder. 3 parts of this particle powder and 1000 parts of polycarbonate resin pellets were melt-kneaded to obtain a composition containing 0.3% by weight of particles dispersed therein. This composition was extruded into a sheet to obtain a polycarbonate sheet having a thickness of 3 mm.
The obtained polycarbonate sheet had an ultraviolet ray shielding property of ◎, a visible light transmittance of ○, and a heat ray shielding property of ◎.
[0104]
-Example 3-14-
250 parts of the dispersion (DE6) obtained in Example 2-5, 60 parts of an acrylic resin (OHV50 / resin, solid content resin concentration 50% by weight), a curing agent resin (isocyanurate-modified hexamethylene diisocyanate, NCO group) A coating composition consisting of 5 parts (containing 23% by weight) was prepared. This paint was formed on one side (corona treated) of a 25 μm-thick PET film (base film) by a gravure coating method so as to have a dry film thickness of 4.3 μmJ and dried (95 ° C., 2 minutes). Thus, a PET film provided with a particle dispersion coating was obtained.
[0105]
Next, an acrylic pressure-sensitive adhesive was applied to the dispersion film side of the PET film provided with the particle dispersion coating with a comma coater so as to have a dry film thickness of 16 μm. A release film-treated PET film (release film, thickness: 50 μm) was attached to the coated surface to obtain a laminated film including a base film, a zinc oxide-based fine particle dispersion layer, an adhesive layer, and a release film layer.
This laminated film is an adhesive laminated film excellent in ultraviolet ray shielding property, and has ultraviolet ray shielding property of ◎, visible light transmittance of ○, heat ray shielding property of ◎, transparency of less than 4% haze, and colorlessness of ◎. Met.
[0106]
-Example 3-15-
In Example 3-14, as a base film, a PET film in which a hard coat layer (film thickness of 2 μm) made of an ultraviolet-curable urethane acrylate resin was used in advance, and one side of the hard coat layer was used. In the same manner as in Example 3-14, a laminated film in which a zinc oxide-based fine particle dispersion layer, an adhesive layer, and a release film layer were sequentially formed was obtained. This laminated film was excellent in ultraviolet ray shielding property, heat ray shielding property, transparency, light resistance, weather resistance and scratch resistance.
[0107]
【The invention's effect】
The zinc oxide-based particles according to the present invention are novel particles excellent in ultraviolet ray shielding property or heat ray shielding property.
The method for producing zinc oxide-based particles according to the present invention can produce the zinc oxide-based particles with good reproducibility and efficiently.
The zinc oxide-based particle-containing composition according to the present invention can form a coating film or the like excellent in ultraviolet shielding property or heat ray shielding property.
The coated article according to the present invention is excellent in ultraviolet ray shielding property or heat ray shielding property.

Claims (9)

Zinc oxide-based particles which contain a trivalent and / or tetravalent metal element ( M ) and Zn as metal components and exhibit zinc oxide crystallinity by X-ray diffraction,
M is contained at 0.1 to 20 atomic% with respect to Zn,
Zinc oxide-based particles characterized in that the UV transmission end TI _uv obtained by powder diffuse reflectance measurement satisfies TI _uv ≧ 370 nm. When the reflectance at the wavelength 1000nm obtained by powder powder diffuse reflectance measurement and R (1000), the maximum reflectance at a wavelength of 380~780nm was R (λ _max),
R (1000) / R (λ _max ) <0.8
Satisfied, zinc oxide-based particles according to claim 1. When the crystallite size Ds (hkl) in the vertical direction is obtained for two lattice planes (100) and (002) using the Scherrer method (Cauchy function approximation),
Ds (002) / Ds (100) <1.5
The zinc oxide-based particles according to claim 1 or 2, which satisfy the following. The zinc oxide-based particles according to any one of claims 1 to 3, which are surface-treated with at least one surface treatment agent selected from a metal carboxylate and a metal alkoxide. Zinc oxide is obtained from a solution obtained by mixing a zinc compound and / or a hydrolytic condensate thereof, a compound of a metal element ( M ) which is trivalent and / or tetravalent and / or a hydrolytic condensate thereof, and an alcohol. In the method for producing zinc oxide-based particles to precipitate the system-based particles,
In the solution, a compound represented by the following general formula (I) is used as a zinc compound, and M is 0.1 to 20 atomic% with respect to Zn, and a water content is 4 or less with respect to Zn in a molar ratio. A method for producing zinc oxide-based particles, which is prepared.
Zn (O) _k (OCOR) _x (OH) _y (OR ') _z (I)
(However, R is at least one selected from a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group and an aralkyl group; R ′ is at least one selected from an alkyl group, a cycloalkyl group, an aryl group and an aralkyl group One kind; k, x, y and z satisfy k = (2-xyz) / 2, x + y + z ≦ 2, 0 <x ≦ 2, 0 ≦ y <2, and 0 ≦ z <2. ) The method for producing zinc oxide-based particles according to claim 5, wherein the particles after the precipitation are subjected to a surface treatment with at least one surface treatment agent selected from a metal carboxylate and a metal alkoxide. An oxide comprising the zinc oxide-based particles according to any one of claims 1 to 4 and a binder component, wherein the ratio of the zinc oxide-based particles to the total solid content of the two is 0.1 to 99% by weight. A composition containing zinc-based particles. A coated body obtained by forming a coating film obtained from the zinc oxide-based particle-containing composition according to claim 7 on a surface of a substrate. A coated article formed by applying a liquid containing the zinc oxide-based particles according to any one of claims 1 to 4 and a solvent to a substrate surface and heating the liquid to form a thin film.