JP3558342B2 - Lightweight clay and method for producing the same - Google Patents

Description

【００５７】
［式（１）中、記号Ｍは、水素、アルカリ金属、またはアンモニウムおよびアミンイオンで表されるいずれかの陽イオン、ＸおよびＹは、相互に独立の置換基であって、ＮＨ_２、Ｎ（Ｃ_２Ｈ_４ＯＨ）_２、Ｎ（ＣＨ_２ＣＨ（ＯＨ）ＣＨ_３）_２、またはＮＲ^１Ｒ^２（Ｒ^１およびＲ^２は、水素または炭素数１〜２０の炭化水素基である。）で表されるいずれかの置換基である。］
【００５８】
【式２】

【００５９】
［式（２）中、記号ＸおよびＹは、相互に独立の置換基であって、ＳＯ_２Ｍ（記号Ｍは、水素、アルカリ金属、またはアンモニウムおよびアミンイオンで表されるいずれかの陽イオン）、ＮＨ_２、Ｎ（Ｃ_２Ｈ_４ＯＨ）_２、Ｎ（ＣＨ_２ＣＨ（ＯＨ）ＣＨ_３）_２、またはＮＲ^１Ｒ^２（Ｒ^１およびＲ^２は、水素または炭素数１〜２０の炭化水素基である。）で表されるいずれかの置換基である。］
【００６０】
【式３】

【００６１】
［式（３）中、記号Ｘは、ＮＨ_２、Ｎ（Ｃ_２Ｈ_４ＯＨ）_２、Ｎ（ＣＨ_２ＣＨ（ＯＨ）ＣＨ_３）_２、またはＮＲ^１Ｒ^２（Ｒ^１およびＲ^２は、水素または炭素数１〜２０の炭化水素基である。）で表されるいずれかの置換基である。］
【００６２】
（２）密度
また、蛍光増白剤の密度を０．９〜２．０ｇ／ｃｍ^３（測定温度：２０℃、以下同様である。）の範囲内の値とすることが好ましい。
この理由は、かかる蛍光増白剤の密度がこのような範囲外の値となると、軽量粘土中に均一に混合することが困難となる場合があるためである。したがって、蛍光増白剤の密度を１．０〜１．６ｇ／ｃｍ^３の範囲内の値とすることがより好ましく、１．１〜１．４ｇ／ｃｍ^３の範囲内の値とすることがさらに好ましい。
【００６３】
（３）粘度
また、蛍光増白剤の粘度を５〜１，０００ｍＰａ・ｓ（測定温度：２０℃、以下同様である。）の範囲内の値とすることが好ましい。
この理由は、かかる蛍光増白剤の粘度が５ｍＰａ・ｓ未満の値となると、軽量粘土中に均一に混合することが困難となる場合があるためである。一方、かかる蛍光増白剤の粘度が１，０００ｍＰａ・ｓを超えると、凝固して取り扱いが困難となるばかりか、軽量粘土中に均一に混合することが困難となる場合があるためである。
したがって、蛍光増白剤の粘度を１０〜５００ｍＰａ・ｓの範囲内の値とすることがより好ましく、３０〜２００ｍＰａ・ｓの範囲内の値とすることがさらに好ましい。
【００６４】
（４）ｐＨ
また、蛍光増白剤のｐＨを７．１〜１０の範囲内の値とすることが好ましい。この理由は、かかる蛍光増白剤のｐＨが７．１未満の値となると、軽量粘土が過度にゲル化して、保存安定性が乏しくなる場合があるためである。一方、かかる蛍光増白剤のｐＨが１０を超えると、取り扱いが困難となる場合があるためである。
したがって、かかる蛍光増白剤のｐＨを７．５〜９．５の範囲内の値とすることがより好ましく、８〜９の範囲内の値とすることがさらに好ましい。
【００６５】
（５）添加量
また、蛍光増白剤の添加量を、全体量に対して、０．００１〜５重量％の範囲内の値とすることが好ましい。
この理由は、かかる蛍光増白剤の添加量が０．００１重量％未満となると、添加効果が発現せず、軽量粘土のＬ値の調整が困難となる場合があるためである。一方、かかる蛍光増白剤の添加量が５重量％を超えると、軽量粘土のＬ値が飽和するとともに、蛍光増白剤が外部にブリードする場合があるためである。
したがって、蛍光増白剤の添加量を、全体量に対して、０．０１〜３重量％の範囲内の値とすることがより好ましく、０．０５〜１重量％の範囲内の値とすることがさらに好ましい。
【００６６】
また、蛍光増白剤の添加量を、有機中空微小球を基準にして、決定することも好ましい。すなわち、有機中空微小球の添加量をＦ１とし、蛍光増白剤の添加量をＦ２としたときに、Ｆ１／Ｆ２の値を１〜１００の範囲内の値とすることが好ましい。
この理由は、かかるＦ１／Ｆ２の値が１未満の値になると、軽量粘土のＬ値が飽和するとともに、軽量粘土の軽量化が困難となる場合があるためである。一方、かかるＦ１／Ｆ２の値が１００を超えると、軽量粘土のＬ値の調整が困難となる場合があるためである。
したがって、かかるＦ１／Ｆ２の値を２〜５０の範囲内の値とすることがより好ましく、５〜３０の範囲内の値とすることがさらに好ましい。
【００６７】
７．ゲル化剤
（１）種類
また、ポリビニルアルコール等の主剤に対して、ゲル化剤を添加することが好ましい。このようにゲル化剤を添加することにより、軽量粘土の取り扱い性や成型性を著しく向上させることができるためである。
このようなゲル化剤としては、硼酸、硼砂、コンゴーレッド、レゾルシノール、カテコール、フロログルシノール、パンサン、没食子酸、クロム酸（三価）、重クロム酸、チタン酸、バナジン酸等の一種単独または二種以上の組み合わせが挙げられる。これらのうち、硼酸および硼砂は、特にポリビニルアルコールのゲル化の制御が容易なことから好ましいゲル化剤である。
【００６８】
（２）添加量
また、ゲル化剤の添加量は、軽量粘土の取り扱い性や成型性を考慮して定めることが好ましいが、例えば、ポリビニルアルコール１００重量部に対して、０．０１〜１０重量部の範囲内の値とすることが好ましい。
この理由は、かかるゲル化剤の添加量が０．０１重量部未満の値となると、添加効果が発現しない場合があるためである。一方、かかるゲル化剤の添加量が１０重量部を超えると、軽量粘土におけるポリビニルアルコールのゲル化の制御が困難となる場合があるためである。
したがって、かかるゲル化剤の添加量を、ポリビニルアルコール１００重量部に対して、０．０５〜５重量部の範囲内の値とすることがより好ましく、０．１〜１重量部の範囲内の値とすることがさらに好ましい。
【００６９】
８．フィラー
（１）種類
また、軽量粘土中に、有機フィラーや無機フィラーを添加することが好ましい。この理由は、このようなフィラーを添加することにより、軽量粘土の造形性や軽量性、あるいは白色度にさらに優れた軽量粘土を得ることができるためである。
このようなフィラーとしては、例えば、ポリメチルメタクリレート、ポリエチルアクリレート、ポリスチレン、スチレン−アクリロニトリル共重合体、スチレン−酢酸ビニル共重合体、ポリ酢酸ビニル、エチレン−酢酸ビニル共重合体、ポリエチレン、エチレン−アクリル酸共重合体、ポリプロピレン、ポリ塩化ビニリデン、塩化ビニリデンーアクリロニトリル共重合体、フェノール樹脂、グアナミン樹脂、尿素樹脂、炭酸カルシウム、タルク、酸化チタン、シリカ、マイカ、ジルコニウム、アルミナ、酸化クロム、酸化スズ、酸化鉛、酸化インジウム、カーボン、ガラス、アラミド繊維等が挙げられる。
特に、タルクは、安価であって、しかも平均粒径が適当であることから取り扱いやすく、軽量粘土の造形性や軽量性の調整において好ましいフィラーである。
【００７０】
（２）添加量
また、かかるフィラーを添加する場合、その添加量を、軽量粘土の全体量を１００重量％としたときに、０．１〜２０重量％の範囲内の値とすることが好ましい。
この理由は、かかるフィラーの添加量が０．１重量％未満の値になると、添加効果が発現しない場合があるためである。一方、かかるフィラーの添加量が２０重量部以上になると、軽量粘土の造形性や軽量性が逆に低下する場合があるためである。
したがって、フィラーの添加量を、軽量粘土の全体量を１００重量％としたときに、０．５〜１５重量％の範囲内の値とすることがより好ましく、１〜１０重量％の範囲内の値とすることがさらに好ましい。
【００７１】
９．白色度
（１）白色度（ＷＬ）
また、ＪＩＳ Ｌ ０８０３に準拠して測定される軽量粘土の白色度（ＷＬ）を７０以上の値とすることを特徴とする。
この理由は、かかる軽量粘土の白色度（ＷＬ）が７０未満の値になると、美的外観性が低下し、また、色素を添加した場合に、混濁して、発色性が著しく低下するためである。ただし、かかる白色度（ＷＬ）の値が高くなりすぎると、使用可能な構成材料の種類等が過度に制限される場合がある。
したがって、かかる有機中空微小球の白色度（ＷＬ）を７０〜９９．９の範囲内の値とすることが好ましく、８０〜９９の範囲内の値とすることがさらに好ましい。
【００７２】
ここで、図４および図５に示す特性図を参照して、軽量粘土の白色度（ＷＬ）と、発色性の評価結果との関係を説明する。図４は、横軸に軽量粘土の白色度（ＷＬ）の値を採って示してあり、縦軸に、発色性の評価結果（相対値）を採って示してある。また、黒丸（●）の特性曲線が、青色色素を０．０２重量％添加した場合であって、黒三角（▲）の特性曲線が、黄色色素を０．１重量％添加した場合である。なお、発色性の評価結果（相対値）は、実施例１に示す評価◎を評価点５、○を評価点４、△を評価点２、×を評価点１、××を評価点０としたものである。
このような図４に示す特性曲線から、青色色素および黄色色素を添加したそれぞれ軽量粘土において、白色度（ＷＬ）が高い程、発色性評価点が高い傾向があり、特に、白色度（ＷＬ）が５０以上であれば、良い評価点が得られることが理解される。
また、図５は、横軸に蛍光増白剤の添加量（重量％）を採って示してあり、縦軸に、青色色素を０．０２重量％添加した場合の発色性の評価結果（相対値）を採って示してある。また、黒丸（●）が、軽量粘土の白色度（ＷＬ）が５０以上の場合（ＷＬ＝６０）であり、黒三角（▲）が、軽量粘土の白色度（ＷＬ）が５０未満の場合（ＷＬ＝０）である。結果から理解されるように、軽量粘土の白色度（ＷＬ）が５０以上の場合には、０．０５〜０．１重量％程度の蛍光増白剤を添加することによって、３以上の評価点が得られている。それに対して、軽量粘土の白色度（ＷＬ）が５０未満の場合には、０．３〜０．５重量％程度の多くの蛍光増白剤を添加した場合であっても、評価点は１以下の低いままである。
よって、軽量粘土の白色度（ＷＬ）を５０以上の値とすることにより、蛍光増白剤を少量添加した場合であっても、優れた発色性が得られることが理解される。
【００７３】
（２）白色度（ＷＢ）、白色度（ＷＬ）、視感明度（Ｌ値）
また、ＪＩＳ Ｌ ０８０３に準拠して測定される白色度（ＷＬ）に類似した白色度の指標として、青色反射率による白色度（ＷＢ）、ハンター方式による白色度（ＷＨ）、および視感明度（Ｌ値）がある。
これらの白色度は、ＪＩＳ Ｌ ０８０３に準拠した白色度（ＷＬ）とは独立に測定される値であるが、軽量粘土の白色性をこれらの白色度で表した場合、例えば、青色反射率による白色度（ＷＢ）であれば、６０〜９５の範囲内の値であることが好ましい。同様に、ハンター方式による白色度（ＷＨ）であれば、７０〜９８の範囲内の値であることが好ましく、さらに視感明度（Ｌ値）であれば、８０〜９９の範囲内の値であることが好ましい。
【００７４】
１０．他の添加物
軽量粘土中に、添加剤として、上述した添加物以外に、防カビ剤、抗菌剤、酸化防止剤、紫外線吸収剤、油類、ワックス類、グリセリン、増粘剤、可塑剤、界面活性剤、有機溶剤等の一種単独、または二種以上の組み合わせを添加することも好ましい。
【００７５】
１１．製造方法
（１）混合工程
有機中空微小球、色素、極性化合物、繊維、および水等の配合原料を均一に混合する工程である。例えば、これらの配合原料を均一に混合分散できるように、プロペラミキサー、ニーダー、プラネタリーミキサー、三本ロール、ボールミル等を使用することが好ましい。
特に、有機中空微小球は軽くて、混練している間に破壊されやすい一方、分散にばらつきが生じやすいために、ニーダーを使用して、回転数１０〜１，０００ｒｐｍ、時間１〜６０分の条件で、押し出し混練することが好ましく、より好ましくは、回転数３０〜３００ｒｐｍ、時間１０〜３０分の条件で、押し出し混練することである。
また、色素についても、均一に混合分散できるように、予め、水やアルコールに分散させて溶液状に調整するとともに、その溶液が凝集しないように、アルカリ剤等を添加して、ｐＨを７以上の値に調整しておくことが好ましく、８〜１０の範囲内の値に調整しておくことがより好ましく、８．５〜１０の範囲内の値に調整しておくことがさらに好ましい。
また、配合原料を混合する際には、例えば、３０〜７０℃の範囲内の温度に維持することが好ましい。
この理由は、かかる混合温度が３０℃未満となると、配合原料が均一に混合しない場合があるためであり、一方、混合温度が７０℃を超えると、得られる軽量粘土の伸びがなくなり、もろくなる場合があるためである。
したがって、配合原料を混合する際の混合温度を３５〜６０℃の範囲内の温度に維持することがより好ましく、４０〜５５℃の範囲内の温度に維持することがさらに好ましい。
【００７６】
（２）粘度調整工程
また、軽量粘土の粘度を調整する工程である。水やアルコール、あるいは有機溶剤を添加して、軽量粘土の粘度を、例えば、１×１０^３〜１×１０^９ｍＰａ・ｓ（測定温度：２５℃、以下同様である。）の範囲内の値とすることが好ましい。この理由は、かかる軽量粘土の粘度が１×１０^３ｍＰａ・ｓ未満の値となると、表面のべたつきが多くなり、取り扱い性が低下する場合があるためであり、一方、軽量粘土の粘度が１×１０^９ｍＰａ・ｓを超えると、得られる軽量粘土の伸びがなくなり、もろくなり、逆に取り扱い性が低下する場合があるためである。したがって、かかる軽量粘土の粘度を１×１０^４〜１×１０^８ｍＰａ・ｓの範囲内の値とすることがより好ましく、１×１０^５〜１×１０^７ｍＰａ・ｓの範囲内の値とすることがさらに好ましい。
【００７７】
（３）パッケージング工程
作成した軽量粘土を小分けして、パッケージングする工程を設けることが好ましい。すなわち、通常、軽量粘土は、水やアルコール等を比較的多量に含んでいるため、軽量粘土における含水量を維持して、取り扱い性を維持するために、防湿性材料、例えば、ポリエチレンやポリプロピレン等のプラスチック材料で包装することが好ましい。
ただし、未発泡の有機中空微小球における脱ガスによる膨張問題を低下させるために、包装材料に通気孔を設けておくか、あるいはガス透過性材料から包装材料を構成することが好ましい。
この場合、軽量粘土における含水量の維持と、膨張問題の低下とのバランスを採るため、通気孔の大きさを０．０１〜１００μｍの範囲内の値とすることが好ましく、０．０５〜５０μｍの範囲内の値とすることがより好ましく、０．１〜２０μｍの範囲内の値とすることがさらに好ましい。
【００７８】
【実施例】
［実施例１］
（１）軽量粘土の作成
容量１００リットルのニーダー内に、以下の配合材料を収容した後、回転数４０ｒｐｍで、ニーダーを回転させて、軽量粘土を作成した。

なお、均一に配合材料を混合した後、全体量に対して、タルク（密度：２．８２ｇ／ｃｍ^３）を８重量％の割合で添加し、実施例１の軽量粘土とした。また、軽量粘土の白色度をカラーメーターＴＣ−１８００ＭＫ２（東京電色社製）を用いて測定したが、その場合には、上記配合から、イエロー顔料色素を除いた軽量粘土の配合とした。
【００７９】
（２）軽量粘土の評価
得られた軽量粘土につき、以下のような造形性（成膜性）、軽量性、発色性、べたつき性および膨張性（保管性）の評価をそれぞれ行った。得られた結果（ｎ数＝５の平均評価）を表１に示す。
【００８０】
▲１▼造形性
軽量粘土の造形性（成膜性）を、以下の基準で評価した。なお、○以上の評価が得られれば、軽量粘土に適した造形性を有していると言える。
◎：ロールを用いて厚さ０．２ｍｍ以下のフィルムを成膜することができる。
○：ロールを用いて厚さ１ｍｍ以下のフィルムを成膜することができる。
△：ロールを用いて厚さ５ｍｍ以下のフィルムを成膜することができる。
×：ロールを用いても、厚さ５ｍｍ以下のフィルムを成膜することができない。
【００８１】
▲２▼軽量性
軽量粘土の軽量性を、以下の基準で評価した。なお、○以上の評価が得られれば、軽量粘土として十分な軽量性を有していると言うことができる。
◎：密度が０．３ｇ／ｃｍ^３以下の値である。
○：密度が０．５ｇ／ｃｍ^３以下の値である。
△：密度が０．７ｇ／ｃｍ^３以下の値である。
×：密度が０．７ｇ／ｃｍ^３を超える値である。
【００８２】
▲３▼発色性
軽量粘土の発色性を、以下の基準で評価した。なお、○以上の評価が得られれば、軽量粘土の発色性が良好であると言うことができる。
◎：透明感のある鮮明な色である。
○：鮮明な色である。
△：少々鮮明な色である。
×：不鮮明な色である。
××：混濁しており、添加した色素とは異なる色である。
【００８３】
▲４▼べたつき性
軽量粘土のべたつき性を、指触して、以下の基準で評価した。なお、○以上の評価が得られれば、軽量粘土のべたつき性が良好であると言うことができる。
◎：べたつきがほとんど無い。
○：少々のべたつきがある。
△：顕著なべたつきがあるが、軽量粘土が指に転写はしない。
×：顕著なべたつきがあり、軽量粘土が指に転写する。
【００８４】
▲５▼膨張性
１００ｇの軽量粘土を長方形に成形し、その周囲を厚さ１００μｍのポリエチレンフィルムで包装した。この状態で、４０℃のオーブンに１週間放置した後、容積を測定し、初期容積との関係から以下の基準で膨張性（保管性）を評価した。なお、○以上の評価が得られれば、軽量粘土に適した膨張性（保管性）を有していると言える。
◎：容積変化率が３％未満である。
○：容積変化率が１０％未満である。
△：容積変化率が３０％未満である。
×：容積変化率が３０％以上である。
【００８５】
▲６▼耐候性
軽量粘土の耐候性を、以下の基準で評価した。なお、○以上の評価が得られれば、軽量粘土に適した耐候性を有していると言える。
◎：紫外線を１０００ｍＪ／ｃｍ^２照射しても、変色しない。
○：紫外線を５００ｍＪ／ｃｍ^２照射しても、ほとんど変色しない。
△：紫外線を５００ｍＪ／ｃｍ^２照射した場合に、わずかに変色する。
×：紫外線を５００ｍＪ／ｃｍ^２照射した場合に、顕著に変色する。
【００８６】
▲７▼耐ブリード性
軽量粘土における色素顔料の耐ブリード性を、以下の基準で評価した。なお、○以上の評価が得られれば、軽量粘土に適した耐ブリード性を色素顔料が有していると言える。
◎：軽量粘土を５分間、手でこねた場合でも、色素顔料が手に付着しない。
○：軽量粘土を５分間、手でこねた場合でも、ほとんど色素顔料が手に付着しない。
△：軽量粘土を５分間、手でこねた場合に、色素顔料が少々手に付着する。
×：軽量粘土を５分間、手でこねた場合に、色素顔料が顕著に手に付着する。
【００８７】
［実施例２〜４、および比較例１〜３］
表１に示すように、有機中空微小球の種類（実施例４および比較例１〜３では、平均粒径１００μｍ、白色度（ＷＬ）およびＬ値がそれぞれ５０未満、酸性の茶色有機中空微小球を使用）、平均粒径、添加量を変えるとともに、繊維や水の添加量を変えて、実施例１と同様に軽量粘土を作成した。得られた軽量粘土につき、実施例１と同様に評価した。得られた結果を表１に示す。
結果から容易に理解されるように、有機中空微小球の添加量が６重量％を超えると、軽量粘土における造形性や発色性、あるいは膨張性の評価が著しく低下することが判明した。
また、一方、繊維材の添加量が１０重量％未満であっても、従来の知見と異なり、軽量粘土において、十分な軽量化を図れることが判明した。
さらに、水の添加量についても、従来の知見と異なり、水の添加量が６０重量％を超えても、軽量粘土におけるベタツキ性について適当な値に十分調節できることが判明した。
【００８８】
【表１】

【００８９】
［実施例５〜８、および比較例１〜３］
表１に示すように、全体量（１００重量％）に対する蛍光増白剤（アニオン性スルホン酸スチルベン化合物、性状：液体、密度：１．２２ｇ／ｃｍ³、ｐＨ：８〜９、粘度：３０〜５０ｍＰａ・ｓ（測定温度：２０℃））の添加量、およびＣＭＣとＰＶＡの配合比を変えた以外は、実施例１と同様に軽量粘土を作成した。次いで、得られた軽量粘土につき、実施例１と同様に評価した。得られた結果を表２に示す。結果から容易に理解されるように、蛍光増白剤を所定量添加することにより、得られる軽量粘土の白色度（ＷＬ）を７０以上の値に容易に調整できるようになった。また、蛍光増白剤を所定量添加することにより、耐候性や発色性についても、著しく改良できるようになった。したがって、成形した軽量粘土を窓際の日が当る場所に長時間置いていたとしても、優れた発色性を維持することが期待される。
【００９０】
【表２】

【００９１】
［実施例５〜８、および比較例１〜３］
本発明の軽量粘土によれば、有機中空微小球の平均粒径を１５〜１５０μｍの範囲内の値とするとともに、かかる有機中空微小球の添加量を、全体量に対して、０．１〜６重量％の範囲内の値とし、かつ、ＪＩＳ Ｌ ０８０３に準拠して測定される軽量粘土の白色度（ＷＬ）を７０以上の値とすることにより、発色性、造形性、および軽量性に優れ、しかも、包装材で被覆して長期間保管した場合や、夏季等に周囲温度が上昇して、高温状態になった場合であっても膨張問題を解消して優れた保管性が得られるとともに、製造コストが安価である軽量粘土を提供することが可能になった。
また、本発明の軽量粘土において、ＣＭＣとＰＶＡの配合比を１００：４０〜１００：５００の範囲内の値にすることにより、所定形状への造形が容易であるとともに、従来の軽量粘土では困難であった薄膜化、例えば厚さ０．１ｍｍ以下のフィルム化が可能となり、装飾材料や折り紙等の用途にも使用することが可能となった。
また、本発明の軽量粘土において、０．０５〜０．２μｍの平均粒径を有し、かつ、粒度分布における標準偏差を０．０５μｍ以下の値にした色素顔料を所定量添加することにより、極めて優れた発色性を有するとともに、優れた耐光性や色素顔料の耐ブリード性が得られるようになった。
さらにまた、本発明の軽量粘土の製造方法によれば、平均粒径が１５〜１５０μｍの範囲内の値である有機中空微小球を使用するとともに、ニーダーを用いて混練し、有機中空微小球の添加量を、全体量に対して、０．１〜６重量％の範囲内の値とし、かつ、ＪＩＳ Ｌ ０８０３に準拠して測定される軽量粘土の白色度（ＷＬ）を７０以上の値とすることにより、発色性、造形性、および軽量性に優れ、しかも、保管性（膨張性）にも優れた軽量粘土を安価に提供することが可能になった。
【００９２】
【図面の簡単な説明】
【図１】軽量粘土における有機中空微小球の添加量と、軽量粘土の軽量性および造形性との関係を示す特性図である。
【図２】軽量粘土における有機中空微小球の添加量と、膨張性評価結果との関係を示す特性図である。
【図３】軽量粘土における有機中空微小球の添加量と、製造原価割合との関係を示す特性図である。
【図４】軽量粘土における白色度（ＷＬ）と、発色性との関係を示す特性図である。
【図５】軽量粘土における蛍光増白剤の添加量と、発色性との関係を示す特性図である。
【図６】（ａ）本発明の軽量粘土における色素顔料の平均粒径と、光の透過性（発色性）との関係を説明するために供する図である。
（ｂ）従来の軽量粘土における色素顔料の平均粒径と、光の透過性（発色性）との関係を説明するために供する図である。
【図７】（ａ）本発明の軽量粘土における色素顔料の添加量と、光の透過性（発色性）との関係を説明するために供する図である。
（ｂ）従来の軽量粘土における色素顔料の添加量と、光の透過性（発色性）との関係を説明するために供する図である。
【００９３】
【符号の説明】
１０：色素顔料
１２：有機中空微小球
１４、１６、２４、２６：光[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a lightweight clay and a method for producing the same, and more particularly, to a lightweight clay which has appropriate lightness and formability, is excellent in color development, and is inexpensive to produce, and a method for producing the same.
[0002]
[Prior art]
Clays used for conventional arts and crafts and school teaching materials are mainly made of granular materials or disintegrated plant bodies, and a binder, fragrance, pigment, moisture, and oil for binding the granular materials to this main material. In many cases, additives such as additives are added. Therefore, there was a problem that the conventional clay was heavy and inconvenient to use.
For this reason, Japanese Patent Publication No. 51-893 discloses a lightweight clay composed mainly of powdered styrene foam and added with pulp material, water and the like.
However, the powdered polystyrene foam has a large number of voids on its surface due to its structure, and when water or the like penetrates into these voids, it becomes rich in water or liquid. For this reason, there remains a problem in weight reduction that the weight of the entire lightweight clay is not reduced so much. In addition, there was also a manufacturing problem that it was not easy to miniaturize the polystyrene foam and it was difficult to uniformly mix the polystyrene with the compounding material.
[0003]
JP-B-59-50615 discloses that 30 to 40% by weight of fine hollow particles made of a foamed inorganic material having a particle size of less than 150 μm and a bulk specific gravity of 0.6 or less, and a fiber length of 10 mm or less. 3-13% by weight of fiber powder, 31-60% by weight of talc powder having a particle size of 150 μm or less, 3-8% by weight of water-soluble synthetic paste alone or in combination, and water A glazing molding clay having a penetration adjusted to 100 to 350 is disclosed, and a sculpture material having a similar structure is disclosed in Japanese Patent Publication No. 57-16356.
However, such molding clays and sculptures are difficult to mix and disperse due to the large amount of fine hollow particles or rock powder made of expanded inorganic material. However, there was a problem that the handling and the formability were poor and the manufacturing cost was high.
[0004]
JP-A-2-123390 discloses that organic hollow microspheres whose outer shell is made of a copolymer containing acrylonitrile or vinylidene chloride are 3 to 20% by weight based on the total amount of a synthetic binder (carboxymethylcellulose). ) Is 5 to 20% by weight, fiber powder is 10 to 30% by weight, and water is 50 to 60% by weight, so that it is lightweight, has high whiteness, and can be easily incinerated. Has been proposed.
That is, for example, when the blending ratio of the organic hollow microspheres is less than 3% by weight, a predetermined target weight cannot be achieved. On the other hand, when the blending ratio of the organic hollow microspheres exceeds 20% by weight, the weight of the lightweight clay is reduced. It is said that the property as is impaired. Further, when the blending ratio of the fiber powder is less than 10% by weight, the function as a binder becomes insufficient. On the other hand, when the blending ratio of the fiber powder exceeds 30% by weight, a large amount of water is stored. It is said that the weight reduction is impaired.
Further, when the mixing ratio of water is less than 50% by weight, the molding operation becomes difficult. On the other hand, when the mixing ratio of water is more than 60% by weight, the water softens and the moldability becomes poor, and furthermore, It is said that weight reduction is impaired.
However, in such a lightweight clay, the addition amount of the organic hollow microspheres is as large as 20% by weight, so that the mixing and dispersion of the organic hollow microspheres is not easy, and the obtained lightweight clay is excessively lightweight. There were problems such as poor handling and formability, and high manufacturing costs.
In addition, since such lightweight clay has a large amount of organic hollow microspheres to be added, there is a problem that so-called unfoamed organic hollow microspheres in which a foaming gas (foaming liquid) remains are present. It was observed. Therefore, when the lightweight clay is covered with a packaging material such as polyethylene film and stored for a long time, or when the ambient temperature rises and becomes high temperature in summer or the like, the residual foaming gas causes There was a problem that the coated lightweight clay expanded to a volume of about 1.2 to 3 times the initial volume (hereinafter referred to as expansion problem).
Furthermore, such a lightweight clay has a problem that, because of the large amount of organic hollow microspheres added, when a pigment is added, the dispersibility of the pigment is inhibited, and excellent color development cannot be obtained. .
[0005]
JP-A-10-268755 discloses that 30 to 70 parts by weight of glass micro hollow spheres having a particle size of 1 to 200 μm, 30 to 60 parts by weight of fiber powder, 10 to 50 parts by weight of carboxymethyl cellulose, A lightweight clay having a light weight, a short drying time, and a small shrinkage by being mixed at a ratio of 400 parts by weight (based on the total amount of glass micro hollow spheres, fiber powder, and carboxymethyl cellulose) is disclosed.
That is, for example, if the mixing ratio of the glass micro hollow spheres is less than 30 parts by weight, it is not possible to achieve a predetermined weight reduction, while if the mixing ratio of such glass micro hollow spheres exceeds 70 parts by weight, This is because shrinkage and cracking in the lightweight clay are increased.
Further, if the compounding ratio of the fiber powder is less than 30 parts by weight, the shrinkage and cracking in the lightweight clay become large, while if the compounding ratio of the fiber powder exceeds 60 parts by weight, a large amount of water is stored. This is because weight reduction is impaired.
Further, when the mixing ratio of the water is less than 200 parts by weight, it is difficult to perform a molding operation on the lightweight clay. On the other hand, when the mixing ratio of the water exceeds 400 parts by weight, the water softens and the molding property is poor. And furthermore it is easy to adhere to the hand.
However, such a lightweight clay has a problem that the glass micro hollow spheres and the fiber powder are added in an excessively large proportion, so that the moldability is poor and the production cost is high. In addition, since such a lightweight clay has a large amount of glass organic hollow microspheres added, when a pigment is added, there is also a problem that the dispersibility of the pigment is inhibited, and excellent color development cannot be obtained. .
[0006]
[Problems to be solved by the invention]
Therefore, the inventors of the present invention examined the average particle size and whiteness (WL) of the organic hollow microspheres in the lightweight clay, or the amount of the organic hollow microspheres to be added in a range where a problem was conventionally caused. It has been found that it exerts an effect and influences the whiteness (WL), color development, formability, lightness, or expansion problem of the lightweight clay.
That is, the present invention is excellent in color development, formability, lightness, and when stored for a long time covered with a packaging material, or when the ambient temperature rises in the summer or the like and the temperature becomes high. It is another object of the present invention to provide a lightweight clay and a method for producing the same, which can solve the problem of swelling, provide excellent storage properties, and have a low production cost.
[0007]
According to the present invention, in the lightweight clay containing the organic hollow microspheres and the binder resin, the average particle diameter of the organic hollow microspheres is set to a value in the range of 15 to 150 μm, and the amount of the organic hollow microspheres added. Is a value of 6% by weight or less based on the total amount, and the whiteness (WL) of the lightweight clay measured according to JIS L 0803 is a value of 70 or more. Is provided, and the above-mentioned problem can be solved.
In other words, by controlling the average particle size of the organic hollow microspheres in a certain range and controlling the whiteness (WL) of the lightweight clay, the aesthetic appearance is improved, and a pigment or the like is used for colorization. When added, excellent color developability can be obtained.
In addition, since the amount of the organic hollow microspheres is relatively small, even when a dye is added for colorization, the dispersibility of the dye is not hindered, and a more excellent coloring property is obtained. Can be.
In addition, by setting the addition amount of the organic hollow microspheres in the conventional lightweight clay to a value considerably smaller than the upper limit (20% by weight), a sufficient and appropriate weight reduction can be achieved and a lightweight clay excellent in formability can be obtained. Obtainable.
Furthermore, since the amount of organic hollow microspheres to be added is relatively small, not only is it easy to mix and disperse lightweight clay, but also to reduce the amount of unfoamed organic hollow microspheres and use expensive organic hollow microspheres. Since the amount can be reduced, excellent storage properties (expandability) can be obtained, and the production cost can be kept low.
[0008]
Further, when constituting the lightweight clay of the present invention, it is preferable that the whiteness (WL) of the organic hollow microspheres measured according to JIS L 0803 is a value of 50 or more.
By using such organic hollow microspheres having a whiteness (WL) of 50 or more and having a high whiteness, not only the whiteness (WL) of the lightweight clay can be easily adjusted, but also the coloring property is further improved. You can get lightweight clay.
[0009]
In constituting the lightweight clay of the present invention, a fluorescent whitening agent is contained, and the amount of the fluorescent whitening agent is set to a value within a range of 0.001 to 5% by weight based on the total amount. Is preferred.
With such a configuration, not only is it easy to adjust the L value of the lightweight clay, but also because the fluorescent whitening agent can effectively absorb ultraviolet light, the weather resistance of the lightweight clay can be significantly improved. Can be. Further, by including the fluorescent whitening agent, the whiteness (WL) of the lightweight clay can be set to a value within a predetermined range even when the whiteness (WL) of the organic hollow microspheres is less than 50.
[0010]
Further, in constituting the lightweight clay of the present invention, it is preferable that the surface of the organic hollow microsphere is subjected to a surface treatment with the fluorescent whitening agent.
With such a configuration, the whiteness (WL) of the lightweight clay can be easily adjusted to a value in a desired range by using a relatively small amount of the optical brightener.
[0011]
Further, in constituting the lightweight clay of the present invention, when the addition amount of the organic hollow microspheres is F1 and the addition amount of the fluorescent whitening agent is F2, the value of F1 / F2 is in the range of 1 to 100. It is preferable to use a value.
By considering the relationship between the addition amount of the organic hollow microspheres and the addition amount of the fluorescent whitening agent, not only the adjustment of the whiteness (WL) in the lightweight clay becomes easy, but also the coloring property is more excellent. You can get lightweight clay.
[0012]
In constituting the lightweight clay of the present invention, the density of the constituent materials other than the organic hollow microspheres is 0.5 to 0.8 g / cm. ² If it is less than 0.1%, the amount of the organic hollow microspheres is set to a value within the range of 0.1 to less than 3% by weight based on the total amount, and the density of the constituent materials other than the organic hollow microspheres is 0.8%. ~ 5g / cm ² In this case, the amount of the organic hollow microspheres added is preferably set to a value within the range of 0.1 to 6% by weight based on the total amount. In this way, by determining the amount of the organic hollow microspheres to be added in consideration of the density of the constituent materials other than the organic hollow microspheres, for example, the binder resin and other additives, a lightweight clay having a desired density can be economically manufactured. Can be provided.
[0013]
In addition, in constituting the lightweight clay of the present invention, a hydroxyl group-containing compound and a carboxyl group-containing compound, or any one of the polar compounds, are further contained, and the amount of the polar compound to be added is 0.1 to the total amount. The value is preferably in the range of 1 to 30% by weight.
By using a polar compound in such a range, it is possible to obtain a lightweight clay having more excellent formability and coloring.
[0014]
Further, in constituting the lightweight clay of the present invention, as the hydroxyl group-containing compound and the carboxyl group-containing compound, carboxymethylcellulose and polyvinyl alcohol are contained, and when the fluorescent whitening agent is not contained, the carboxymethylcellulose and polyvinyl alcohol are blended. The ratio (weight ratio) is set to a value within the range of 100: 40 to 100: 500, and when a fluorescent whitening agent is contained, the mixing ratio (weight ratio) of the carboxymethyl cellulose and polyvinyl alcohol is 100: 550 to 100. : Preferably in the range of 2,000.
With such a configuration, it is possible to obtain a lightweight clay which is excellent in touch and also excellent in formability and coloring. The reason why the mixing ratio (weight ratio) of carboxymethylcellulose and polyvinyl alcohol is changed depending on the presence or absence of the fluorescent whitening agent is that carboxymethylcellulose and the fluorescent whitening agent may react.
[0015]
Further, in constituting the lightweight clay of the present invention, it is preferable that the fibers are further contained and the amount of the fibers added is within a range of 1 to 10% by weight or less based on the total amount.
By using the fibers in such a range, a lightweight clay having more excellent formability and lightness can be obtained.
As described above, conventionally, when the amount of the added fiber is less than 10% by weight with respect to the total amount, it is said that the function as the binder becomes insufficient. By taking into account both the average particle size and the amount added, the restrictions on the amount of such fibers can be greatly relaxed.
[0016]
Further, in constituting the lightweight clay of the present invention, it is preferable that water is further contained and the amount of the water added is a value within the range of 61 to 85% by weight based on the total amount.
By using water in such a range, it is possible to obtain a lightweight clay having more excellent formability and coloring.
As described above, conventionally, when the added amount of water exceeds 60% by weight based on the total amount, it is said that the water is softened, the formability is poor, and the weight reduction is impaired. However, by taking into account both the average particle size and the amount of organic hollow microspheres, such a restriction on the amount of water can be greatly relaxed.
[0017]
Further, in constituting the lightweight clay of the present invention, it is preferable that a pigment is further contained and the amount of the pigment added is within a range of 0.1 to 10% by weight based on the total amount.
By using a pigment in such a range, it is possible to easily colorize and obtain a lightweight clay excellent in coloring properties.
[0018]
In constituting the lightweight clay of the present invention, the average particle size of the pigment is set to a value in the range of 0.05 to 0.2 μm, and the standard deviation in the particle size distribution is set to a value of 0.05 μm or less. Is preferred.
By using such a pigment, it is possible to easily colorize with a small amount of pigment, and it is possible to obtain a lightweight clay excellent in coloring properties.
[0019]
Further, in constituting the lightweight clay of the present invention, when the average particle size of the pigment is D1 and the average particle size of the organic hollow microspheres is D2, the ratio of D2 / D1 is in the range of 10 to 50,000. Is preferable.
By considering the relationship between the pigment and the average particle diameter of the organic hollow microspheres in this way, it is possible to easily colorize with a small amount of pigment and to obtain a lightweight clay excellent in coloring properties.
[0020]
In constituting the lightweight clay of the present invention, the lightweight clay further contains a filler, and the added amount of the filler is set to a value within a range of less than 1 to 20% by weight based on the total amount. Is preferred.
By adding a filler in addition to the organic hollow microspheres as described above, a lightweight clay having more excellent formability, lightness, or whiteness can be obtained.
[0021]
In constituting the lightweight clay of the present invention, the lightweight clay further contains inorganic hollow microspheres, and the addition amount of the inorganic hollow microspheres is 0.01 to 10% by weight based on the total amount. It is preferable to set the value within the range.
By adding inorganic hollow microspheres in addition to organic hollow microspheres in this way, lightweight clay with even better formability and lightness can be obtained, and expansion problems caused by unfoamed organic hollow microspheres And the problem of reduced color developability can be effectively reduced.
[0022]
According to another aspect of the present invention, in the method for producing a lightweight clay containing organic hollow microspheres and a binder resin, the amount of the organic hollow microspheres having an average particle size of 15 to 150 μm is added. To a value of 6% by weight or less based on the total amount, kneading the organic hollow microspheres and the binder resin using a kneader, and measuring the whiteness (WL) of the lightweight clay measured according to JIS L 0803. ) Is 70 or more.
When implemented in this manner, a lightweight clay having excellent shaping properties and lightness, as well as excellent whiteness and further coloring properties when a pigment is added, can be efficiently obtained.
[0023]
An embodiment of the present invention is a lightweight clay containing organic hollow microspheres, a binder resin composed of a polar compound, fibers, water, and a dye, and has an average particle diameter of 15 １５０150 μm, and the amount of the organic hollow microspheres is set to a value of 6% by weight or less based on the total amount, and the whiteness of the lightweight clay is measured according to JIS L 0803. A lightweight clay having a degree (WL) of 70 or more and a method for producing the same.
Hereinafter, the description will be made separately for components such as organic hollow microspheres and polar compounds.
[0024]
1. Organic hollow microspheres
(1) Type 1
The organic hollow microspheres can be suitably used as long as they have an outer shell (shell wall) made of an organic material and have voids therein.
As such organic hollow microspheres, for example, the outer shell is made of vinylidene chloride-acrylonitrile copolymer resin, vinyl acetate-acrylonitrile copolymer resin, methyl methacrylate-acrylonitrile copolymer resin, acrylonitrile resin, etc. , And those containing gas or liquid are preferable.
Among these organic hollow microspheres, in particular, organic hollow microspheres having an outer shell made of vinylidene chloride-acrylonitrile copolymer resin are easy to manufacture, but can be expanded to a desired size when heated. preferable. However, organic hollow microspheres having a shell made of vinylidene chloride-acrylonitrile copolymer resin are colored brown or dark brown when the temperature at the time of foaming is high or when the temperature distribution is uneven, and white. Note that the degree (WL) may be less than 50 in some cases.
Organic hollow microspheres having an outer shell made of vinyl acetate-acrylonitrile copolymer resin, methyl methacrylate-acrylonitrile copolymer resin, acrylonitrile resin, and the like have high whiteness and easy adjustment of whiteness (WL). This is more preferable.
[0025]
(2) Type 2
It is also preferable to use, in addition to the organic hollow microspheres, inorganic hollow microspheres whose outer shell is made of an inorganic material, for example, a glass material.
Such inorganic hollow microspheres are colorless and transparent and have high pressure resistance, for example, 750 psi (1 psi = 6.90 × 10 9 psi). ³ N, 1 kgf = 9.807 N / cm ² The residual ratio when pressurized by the measurement pressure of ()) is 90 to 92 (VOL%) and is light.
Therefore, by using the organic hollow microspheres and the inorganic hollow microspheres together, the weight per unit volume of the lightweight clay can be remarkably reduced, and the organic hollow microspheres exist around the inorganic hollow microspheres. By doing so, the inorganic hollow microspheres can be effectively prevented from being destroyed and the dispersibility of the inorganic hollow microspheres can be further improved by serving as a cushion material.
In addition, by using the organic hollow microspheres and the inorganic hollow microspheres in combination in this manner, in relation to the pigment, the coloring property is increased, the shape retention of the lightweight clay is increased, and the shrinkage rate is reduced. can do.
Furthermore, by using the organic hollow microspheres and the inorganic hollow microspheres in this manner, the amount of the organic hollow microspheres can be relatively reduced. The swelling problem can be effectively prevented, and more excellent storability can be obtained.
[0026]
(3) Whiteness
Further, it is preferable that the color of the organic hollow microspheres is white or a color close thereto. That is, the whiteness (WL) of the organic hollow microspheres measured according to JIS L0803 is preferably set to a value of 50 or more.
The reason for this is that, among the various organic hollow microspheres, the whiteness (WL) of the lightweight clay is easily adjusted by using the organic hollow microspheres having high whiteness (WL) of 50 or more. In addition to the above, it is possible to obtain a lightweight clay which is more excellent in color development when a pigment is added. Conversely, when the whiteness (WL) is less than 50, the organic hollow microspheres have a brownish color and become turbid when added to the lightweight clay together with a pigment, particularly a white pigment or a yellow pigment. This is because coloring properties may be significantly reduced.
However, if the value of the whiteness (WL) is too high, the constituent materials of the organic hollow microspheres may be excessively limited.
Therefore, the whiteness (WL) of such organic hollow microspheres is preferably set to a value in the range of 70 to 99.9, and more preferably to a value in the range of 80 to 99.
In order to adjust the value of the whiteness (WL), white particles such as titanium oxide and silica are added to the outer shell of the organic hollow microspheres, or the periphery is coated with these white particles. Can be achieved more easily. Further, the amount of vinyl chloride resin, vinylidene chloride resin, or formaldehyde resin (phenol resin, melamine resin, guanamine resin, urea resin) or the like used in the outer shell of the organic hollow microspheres is reduced. It can also be easily achieved by setting the value to not more than% by weight. Furthermore, whiteness (WL) can also be easily adjusted by adding or applying a fluorescent color enhancer described below to the outer shell of the organic hollow microspheres.
The whiteness (WL) of such organic hollow microspheres and the whiteness (WL) of a lightweight clay described later can be measured in accordance with JIS L0803, and more specifically, the reflectance is (For example, TR-1000D or TC-1800MK2, manufactured by Tokyo Denshoku Co., Ltd.).
[0027]
(4) Average particle size 1
The average particle diameter of the organic hollow microspheres is set to a value within the range of 15 to 150 μm.
The reason is that when the average particle size of the organic hollow microspheres is less than 15 μm, the formability and whiteness (WL) of the lightweight clay are reduced, and it is difficult to reduce the weight when a predetermined amount is added. This is because there are cases where On the other hand, if the average particle size of the organic hollow microspheres exceeds 150 μm, mixing and dispersion may be difficult, or the formability of the lightweight clay may be reduced.
Therefore, the average particle diameter of the organic hollow microspheres is more preferably set to a value within a range of 50 to 130 μm, and further preferably set to a value within a range of 70 to 120 μm.
The average particle size of the organic hollow microspheres can be calculated using an image processing apparatus by capturing an image of the organic hollow microspheres with an optical microscope and then using the image.
[0028]
(5) Average particle size 2
In determining the average particle size of the organic hollow microspheres, it is preferable to consider the average particle size of the dye described below.
That is, when the average particle size of the dye is D1 and the average particle size of the organic hollow microspheres is D2, the ratio of D2 / D1 is preferably set to a value within the range of 10 to 50,000.
The reason for this is that if the ratio of D2 / D1 is less than 10, the dye is not uniformly dispersed, and the organic hollow microspheres may hinder color development. On the other hand, if the ratio of D2 / D1 exceeds 50,000, the dye is likely to aggregate, and may not be uniformly dispersed, resulting in a decrease in color developability.
Therefore, in order to improve the color developability of the pigment, the ratio of D2 / D1 is more preferably set to a value within the range of 50 to 10,000, and more preferably to a value within the range of 100 to 1,000. More preferred.
[0029]
(6) Addition amount
Further, the addition amount of the organic hollow microspheres is set to a value within the range of 0.1 to 6% by weight based on the total amount.
The reason for this is that if the amount of the organic hollow microspheres is less than 0.1% by weight, it is difficult to reduce the weight of the lightweight clay. On the other hand, when the added amount of the organic hollow microspheres exceeds 6% by weight, the formability and handling of the lightweight clay are remarkably reduced, and the remaining unfoamed organic hollow microspheres increase. This is because, when covered and stored for a long period of time, or when the ambient temperature rises in summer or the like, the packaging material expands and the storage properties are significantly reduced. Further, since the organic hollow microspheres are extremely expensive, if the added amount exceeds 6% by weight, the cost of the obtained lightweight clay becomes extremely expensive.
Therefore, the balance between the formability and expansibility of the lightweight clay, the lightness, and the like becomes better, so that the addition amount of the organic hollow microspheres is set to a value within the range of 0.5 to 4% by weight. More preferably, the value is within a range of less than 1 to 3% by weight.
[0030]
Further, the amount of the organic hollow microspheres added is preferably determined in consideration of the density of the binder resin. That is, by determining the addition amount of the organic hollow microspheres in consideration of the density of the binder resin, it is possible to economically provide a lightweight clay finally having the same density.
More specifically, the density of the constituent materials other than the organic hollow microspheres is 0.5 to 0.8 g / cm. ² If it is less than 0.1%, the amount of the organic hollow microspheres is set to a value within the range of 0.1 to less than 3% by weight based on the total amount, and the density of the constituent materials other than the organic hollow microspheres is 0.8%. ~ 5g / cm ² In this case, the amount of the organic hollow microspheres added is preferably set to a value within the range of 0.1 to 5% by weight based on the total amount.
[0031]
Here, with reference to FIGS. 1 to 3, the relationship between the amount of the organic hollow microspheres to be added, the lightness, the formability, and the expandability of the lightweight clay, and the relationship with the production cost will be described in detail.
FIG. 1 is a numerical representation of the data of lightness and formability in Table 1, with 5 points for ◎, 3 points for ○, 1 point for Δ, and 0 points for ×. Was calculated.
The horizontal axis of FIG. 1 shows the addition amount (% by weight) of the organic hollow microspheres, and the left vertical axis shows the lightness (relative value). Curve A shows the relationship. Is shown. On the other hand, the right vertical axis in FIG. 1 shows the formability (relative value), and the curve B shows the relationship with the addition amount (% by weight) of the organic hollow microspheres.
As can be understood from the characteristic curve shown in FIG. 1, as the amount of the organic hollow microspheres added increases, the evaluation of the lightness of the lightweight clay is improved. It is necessary to set the amount of the added microspheres to a value of 0.1% by weight or more. On the other hand, with respect to the evaluation of the formability of the lightweight clay, on the other hand, it extremely decreased at the addition amount of 3% by weight, the evaluation decreased to 1 at 5% by weight, and further decreased to almost 0 at 7% by weight. I have.
Therefore, by setting the addition amount of the organic hollow microspheres to a value in the range of 0.1 to 6% by weight, a good balance can be achieved between the lightness of the lightweight clay and the formability, and By setting the amount of the organic hollow microspheres to a value within the range of less than 1 to 3% by weight, it can be understood that these characteristics can be more excellently balanced.
[0032]
FIG. 2 is a numerical representation of the expandability data of Table 1, with 5 points for ◎, 3 points for ○, 1 point for Δ, and 0 points for ×. Numerical values were calculated.
The horizontal axis of FIG. 2 shows the addition amount (% by weight) of the organic hollow microspheres, and the left vertical axis shows the expandability (relative value).
As can be understood from the characteristic curve shown in FIG. 2, as the amount of the organic hollow microspheres added increases, the evaluation result of the swelling property decreases. The evaluation is extremely reduced, and the evaluation is reduced to about 1 at 5% by weight, and further reduced to almost 0 at 7% by weight.
Therefore, by taking the results shown in FIGS. 1 and 2 into consideration, by setting the amount of the organic hollow microspheres to a value within the range of 0.1 to 6% by weight, only the lightness and the formability of the lightweight clay can be obtained. In addition, a good balance can be achieved with the problem of swelling during storage. Further, by setting the addition amount of the organic hollow microspheres to a value within a range of less than 1 to 3% by weight, these characteristics can be improved. It can be understood that a better balance can be obtained.
[0033]
FIG. 3 shows the addition amount of the organic hollow microspheres in the lightweight clay, and the production cost of the lightweight clay in the case where the addition amount of the organic hollow microspheres is 2% by weight, assuming 100%. The relationship between the production cost ratio in lightweight clay is shown.
As can be understood from the characteristic curve shown in FIG. 3, as the amount of the organic hollow microspheres increases, the production cost ratio in the lightweight clay tends to increase. When the addition amount is 6% by weight, the production cost ratio increases to about 150%, and when the addition amount is 7% by weight, the production cost ratio increases to about 220%.
Therefore, taking into account the results shown in FIGS. 1 to 3, the addition amount of the organic hollow microspheres is set to a value within the range of 0.1 to 6% by weight. Of the organic hollow microspheres in a range of less than 1 to 3% by weight, thereby further improving these properties. It can be understood that a good balance can be obtained.
[0034]
(7) Bulk density
Further, the bulk density of the organic hollow microspheres is 0.001 to 0.5 g / cm. ³ It is preferable to set the value within the range.
The reason is that the bulk density of such organic hollow microspheres is 0.001 g / cm. ³ When the value is less than the above, it may be difficult to uniformly mix and disperse the compound in the lightweight clay. On the other hand, the bulk density of such organic hollow microspheres is 0.5 g / cm. ³ If the ratio exceeds the above range, the ductility of the lightweight clay may be reduced or the weight may be difficult to reduce.
Therefore, the bulk density of the organic hollow microspheres is 0.005 to 0.2 g / cm. ³ Is more preferably within a range of 0.01 to 0.1 g / cm. ³ It is more preferable to set the value within the range.
The bulk density of such organic hollow microspheres can be measured according to JIS K 5101 (pigment test method).
[0035]
(8) pH value
Further, the pH value of the organic hollow microspheres is preferably set to a value within the range of 3 to 11.
The reason for this is that when the pH value of such organic hollow microspheres is less than 3, a hydroxyl group-containing compound or a carboxyl group-containing compound may be added and gelled when stored for a long period of time.
On the other hand, if the pH value of the organic hollow microspheres exceeds 11, mixing and dispersion and handling may be difficult.
Therefore, organic hollow fine
The pH value of the globules is preferably in the range of 6 to 10.5, and more preferably the pH value is in the range of 7 to 10.5 from neutral to weakly alkaline.
[0036]
(9) Surface treatment
It is preferable that the surface of the organic hollow microspheres is surface-treated with a fluorescent whitening agent described later.
The reason for this is that even when the whiteness (WL) of the organic hollow microspheres is low, the L value of the lightweight clay can be easily adjusted to a desired range with a relatively small amount of the optical brightener. .
It is also preferred that the surface of the organic hollow microspheres is surface-treated with white particles. The reason for this is that by adding white particles such as titanium oxide, silica, alumina, soot, zinc oxide, zinc sulfide, and antimony oxide to the organic hollow microspheres, the L value of the organic hollow microspheres can be adjusted. This is because the dispersibility and the mechanical properties can be improved as well as easily.
Further, it is also preferable to perform a surface treatment around the organic hollow microspheres with a silane coupling agent, a titanium coupling agent or an aluminum coupling agent. The reason for this is that the dispersibility and mechanical properties of the organic hollow microspheres can be remarkably improved by such a treatment with the coupling agent.
In the case where such a surface treatment is performed, if an optical brightener is used, the amount of the optical brightener is set to a value within the range of 0.01 to 1% by weight based on the total amount. Is preferred. Similarly, if white particles are used, the amount of the white particles to be added is preferably in the range of 0.1 to 10% by weight based on the total amount. Further, if the coupling agent treatment is similarly performed, the amount of the coupling agent to be added is preferably set to a value within the range of 0.05 to 5% by weight based on the whole amount.
[0037]
2. Polar compounds
(1) Type
The polar compound as the binder resin is preferably, for example, a hydroxyl group-containing compound or a carboxyl group-containing compound.
In addition, there are compounds such as polyacrylic acid and polyvinyl alcohol each containing both a hydroxyl group and a carboxyl group in the molecule, but for the sake of convenience, the description will be made separately for any one.
[0038]
(1) Hydroxyl-containing compound
Examples of the hydroxyl group-containing compound include polyvinyl alcohol, polyvinyl formal, polyvinyl butyral, polyethylene vinyl acetate, urea resin, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, and the like.
This is because the addition of such a hydroxyl group-containing compound facilitates the adjustment of the malleability and creep resistance of the lightweight clay. In addition, since these hydroxyl group-containing compounds are usually water-soluble, excellent compatibility can be obtained even when water is added to lightweight clay.
In particular, polyvinyl alcohol has a large amount of hydroxyl groups contained per unit weight, and therefore, by adding a relatively small amount, it is possible to effectively improve the malleability and handleability of the lightweight clay, and therefore, a more preferable hydroxyl group-containing compound. It is.
In addition, polyvinyl formal and polyvinyl butyral are resins obtained by acetalizing polyvinyl alcohol with formaldehyde and butyraldehyde, respectively, and are effective when used for obtaining excellent creep resistance and heat resistance in lightweight clay. It is.
Further, polyvinyl acetate is a raw material before saponifying polyvinyl alcohol, but is an effective hydroxyl group-containing compound when a lightweight clay having more excellent malleability is desired.
[0039]
(2) Carboxyl group-containing compound
Examples of the carboxyl group-containing compound include carboxymethyl cellulose (CMC), acrylic acid, and polyvinyl acetate.
Here, when carboxymethylcellulose is used, carboxymethylcellulose having a degree of etherification within a range of 0.1 to 2 is preferable.
The reason for this is that if the degree of etherification of carboxymethylcellulose is less than 0.1, the lightweight clay becomes sticky and handling may be difficult. On the other hand, when the degree of etherification of carboxymethyl cellulose exceeds 2, the ductility of the lightweight clay is reduced, and it may be difficult to form a thin film.
[0040]
(2) Addition amount
The amount of the polar compound to be added is preferably set to a value within the range of 0.1 to 30% by weight based on the total amount (100% by weight) of the lightweight clay.
The reason for this is that if the amount of the polar compound is less than 0.1% by weight, the handling properties and moldability of the lightweight clay may be significantly reduced. On the other hand, when the amount of the polar compound exceeds 30% by weight, the malleability of the lightweight clay may be reduced, or the mixing and dispersion may be difficult.
Therefore, the balance between the handleability and moldability of the lightweight clay and the malleability of the lightweight clay becomes better, so that the amount of the polar compound to be added is set to 0.1 to the total amount of the lightweight clay (100% by weight). The value is preferably in the range of 5 to 20% by weight, more preferably in the range of 1 to 15% by weight, and still more preferably in the range of 2 to 10% by weight.
[0041]
3. fiber
(1) Type
In addition, the type of fiber (pulp) as an additive is not particularly limited, and for example, it is preferable to use hardwood and softwood as raw materials.
However, it can be said that it is more preferable to use a fiber made of hardwood. The reason for this is that fibers made from hardwood are usually shorter in fiber length and averaged than fibers made from softwood, and can be easily dispersed when making lightweight clay. .
[0042]
(2) Average fiber length
Further, the average fiber length of the fibers is preferably set to a value within the range of 0.01 to 20 mm.
The reason for this is that if the average fiber length of such fibers is less than 0.01 mm, the ductility of the lightweight clay may be reduced, or it may be difficult to reduce the weight. On the other hand, if the average fiber length of such fibers exceeds 20 mm, it may be difficult to uniformly mix and disperse the fibers in lightweight clay.
Therefore, since the balance between the malleability of the lightweight clay and the mixing and dispersibility becomes better, it is more preferable to set the average fiber length of the fibers to a value in the range of 0.1 to 10 mm, More preferably, it is set to a value within the range of 5 to 5 mm.
[0043]
(3) Addition amount
Further, the amount of the fiber to be added is preferably determined in consideration of the handleability and moldability of the lightweight clay, or the ease of manufacturing the lightweight clay. For example, the value is preferably in the range of less than 1 to 10% by weight based on the total amount.
The reason for this is that if the amount of such fiber is less than 1% by weight, the effect of addition may not be exhibited. On the other hand, if the amount of the fiber is 10% by weight or more, it may be difficult to control the spreadability and manufacture of the lightweight clay. Therefore, it is more preferable that the amount of the fiber added is in the range of 2 to 9% by weight based on the total amount, and it is further preferable that the amount is in the range of 3 to 8% by weight.
[0044]
4. water
The water is preferably determined in consideration of handleability and moldability of the lightweight clay or ease of manufacturing the lightweight clay. For example, the value is preferably in the range of 61 to 85% by weight based on the total amount.
The reason for this is that if the amount of water added is less than 61% by weight, the effect of addition is not exhibited, and it may be difficult to adjust the lightweight clay. On the other hand, if the amount of such water exceeds 85% by weight, it may be difficult to control the ductility and creep resistance of the lightweight clay.
Therefore, it is more preferable that the amount of the water added be a value within the range of 65 to 83% by weight, more preferably a value within the range of 67 to 80% by weight, based on the total amount.
[0045]
5. Pigment
(1) Type
The type of the pigment is not particularly limited, but may be any pigment that has been conventionally used in the fields of inks, paints, and the like, and examples include organic pigments, inorganic pigments, and dyes.
Such organic pigments include azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, chelated azo pigments, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, and isoindolinones. Examples include pigments, polycyclic pigments such as quinophthalone pigments, dye lakes, and the like.
Examples of the inorganic pigment include oxides such as titanium oxide, red iron oxide, chromium oxide, and iron black, cadmium yellow, chrome vermilion, navy blue, ultramarine blue, carbon black, yellow iron oxide, and pearl pigment.
Furthermore, when more vivid colors are required, plastic type organic pigments based on formalin condensed resin, acrylic resin, guanamine resin, etc., and zinc sulfide, zinc silicate, zinc cadmium sulfide, etc. were sintered. It is also preferable to use an inorganic pigment or the like.
[0046]
(2) Average particle size
Further, it is preferable that the average particle size of the dye is set to a value within a range of 0.01 to 0.2 μm.
The reason for this is that when the average particle size of the pigment is less than 0.01 μm, the pigment tends to agglomerate significantly, making it difficult to uniformly mix and disperse the pigment in lightweight clay, and reducing the color developability. It is. On the other hand, if the average particle size of the pigment exceeds 0.2 μm, the synergistic effect with the organic hollow microspheres is not exerted, and the color developability of the lightweight clay is reduced.
Accordingly, since the balance between the cohesiveness of the dye and the color forming property is better, the average particle size of the dye is more preferably set to a value within the range of 0.06 to 0.18 μm, and 0.07 to 0. More preferably, the value is in the range of 0.12 μm.
It has been found that the smaller the particle size of the pigment, the higher the surface activity and the easier it is to adhere around hollow microspheres having a larger average particle size. However, as will be described in detail below, in the lightweight clay of the present invention, even when the pigment is attached to the hollow microspheres and coats the periphery, compared with the conventional lightweight clay, even if the pigment is adhered to the hollow microspheres, the light clay is more externally exposed. It has been found that it does not interfere much with light.
[0047]
Here, with reference to FIGS. 6A and 6B, the relationship between the average particle size of the dye pigment and the like and the light transmittance, that is, the color forming property will be described in more detail.
FIG. 6A is a schematic diagram showing the relationship between the pigment 10, the organic hollow microspheres 12, and the external light 14 and 16 in the lightweight clay of the present invention. FIG. 6B is a schematic diagram showing the relationship among the pigment 20, the organic hollow microspheres 22, and the external light 24, 26 in the conventional lightweight clay.
As can be understood from FIG. 6 (a), in the lightweight clay of the present invention, the average particle size of the pigment 10 is preferably set to a value less than の of the wavelength of light, and the standard deviation of the particle size distribution. Is further adjusted to a value within a predetermined range, so that even if the pigment 10 adheres to the hollow microspheres 12 and coats the surroundings, the light 14 and 16 from outside are less hindered.
On the other hand, in FIG. 6B, since the average particle size of the pigment 20 is equal to or larger than the wavelength of light, when the pigment 20 adheres to the organic hollow microspheres 22 and covers the periphery, the external In some cases, the transmission of the light 24, 26 from the light may be hindered.
Therefore, in the lightweight clay of the present invention, preferably, light scattering in the organic hollow microspheres 12 is effectively prevented by combining the specific organic hollow microspheres 12 with the pigment pigment 10 having a specific average particle size or the like. As a result, it is possible to obtain a vivid and transparent color developing property.
[0048]
(3) Particle size distribution 1
Further, regarding the particle size distribution of the dye, the standard deviation is preferably set to a value of 0.05 μm or less.
The reason for this is that if the standard deviation of such a dye exceeds 0.05 μm, light scattering becomes large or cohesion is remarkably liable to occur, so that the coloring property of the dye may be reduced.
However, if the standard deviation of such a dye is too small, the production cost may increase due to control.
Therefore, since the balance between the coloring property of the dye and the production cost is better, the standard deviation in the particle size distribution of the dye is more preferably set to a value within the range of 0.04 to 0.01 μm, and 0.03 to 0.01 μm. More preferably, it is set to a value within the range of 0.01 μm.
The standard deviation in the particle size distribution of the dye can be measured, for example, using a laser type particle counter.
[0049]
(4) Particle size distribution 2
Further, it is preferable that 95% of the particle diameter of the dye exists within a range of ± 10% of the average particle diameter.
The reason for this is that by using a pigment having such a narrow particle size distribution, it is possible to obtain a lightweight clay excellent in color developability and formability. Conversely, if 95% of the particle size of the dye exceeds ± 10% of the average particle size, the dye is likely to aggregate, and it is difficult to exhibit a synergistic relationship with the organic hollow microspheres. This is because there is a case where it becomes. Therefore, when the particle size distribution of the dye is widened, the coloring property of the dye may be reduced.
Therefore, in order to obtain more excellent coloring properties with the dye, it is more preferable that 95% of the particle size of the dye exists within the range of ± 8% of the average particle size, and ± 5% of the average particle size. More preferably, it is in the range of%.
The 95% particle size distribution in the average particle size of the dye can be measured, for example, using a laser type particle counter.
[0050]
(5) Addition amount
Further, the amount of the dye added is preferably set to a value within the range of 0.01 to 10% by weight based on the total amount.
The reason for this is that if the amount of the dye is less than 0.01% by weight, the coloring effect of the dye may be reduced without exhibiting the effect of addition or synergy with the organic hollow microspheres. On the other hand, if the added amount of the dye exceeds 10% by weight, light scattering becomes large or coagulation becomes remarkable, and conversely, the coloring property may be reduced.
Therefore, since the coloring property of the dye is improved, the amount of the dye added is more preferably set to a value within the range of 0.05 to 8% by weight, and more preferably to a value within the range of 0.1 to 5% by weight. More preferably,
[0051]
Here, with reference to FIGS. 7A and 7B, the relationship between the amount of the pigment added and the coloring property will be described in more detail.
FIG. 7A is a schematic diagram showing the relationship between the pigment 10, the organic hollow microspheres 12, and the external light 14 and 16 in the lightweight clay of the present invention. FIG. 7 (b) shows the pigment pigment 10, the organic hollow microspheres 22, and the external light 24, 26 when the pigment pigment 10 used in the lightweight clay of the present invention is excessively added. It is a schematic diagram which shows the relationship of.
As can be understood from FIG. 7 (a), in the lightweight clay of the present invention, the amount of the pigment pigment 10 added is such that even if the pigment pigment 10 adheres to the periphery of the organic hollow microspheres 22, it is partially covered. As a result, external light 14 and 16 are less hindered.
On the other hand, in FIG. 7B, the amount of the pigment pigment 10 added is larger than the predetermined range, and the pigment pigment 10 adheres to the periphery of the organic hollow microsphere 22 tightly and sometimes double. , 26 may be impeded.
Therefore, in the lightweight clay of the present invention, preferably, by combining the specific organic hollow microspheres 12 and the pigment pigment 10 in a specific addition amount, light scattering in the organic hollow microspheres 12 is effectively prevented, and the bright clay is vivid. Thus, it is possible to obtain a color developing property having a further transparent feeling.
[0052]
(6) Water dispersibility
Further, the pigment is preferably water-dispersible (including alcohol-dispersible), that is, hydrophilic.
The reason is that by using a pigment having such properties, even when the lightweight clay contains water or alcohol, the pigment can be obtained without coloring and excellent color developability and formability can be obtained. Further, if the dye is water-dispersible, even if the dye is fine particles, it can be stored in water, and further, it can be blended in the storage state of the solution.
[0053]
Further, in order to make the pigment water-dispersible, it is preferable that the acid value of the resin constituting the pigment is in the range of 50 to 300.
The reason for this is that if the acid value of such a resin is less than 50, the water dispersibility of the resulting dye may be significantly reduced, while if the acid value of such a resin exceeds 300, it is obtained. This is because the dye may be easily aggregated. Therefore, since the balance between the water dispersibility of the obtained dye and the cohesiveness is better, the acid value of the resin constituting the dye is more preferably set to a value within the range of 70 to 250, and 90 to 200. It is more preferable to set the value within the range.
Note that the resin constituting the dye preferably has a hydrophilic group such as a carboxyl group, a sulfonic acid group, or a hydroxyl group in the molecule in order to control the acid value within the above range. That is, it is preferable to use a styrene-maleic acid copolymer resin, a styrene-sulfonic acid copolymer resin, a styrene-acrylic acid copolymer resin, or the like.
[0054]
Further, in order to make the dye water-dispersible, it is preferable to use an emulsion containing a surfactant such as an anionic surfactant or a nonionic surfactant as its form.
Examples of such a surfactant include sodium dodecylbenzenesulfonate, sodium lauryl sulfate, ammonium salts of polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, Polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamines, polyoxyethylene alkylamides, and acetylated products thereof may be used alone or in combination of two or more.
[0055]
6. Optical brightener
(1) Type
Examples of the fluorescent whitening agent added to the lightweight clay include a stilbene compound, a stilbene derivative, a stilbene sulfonate compound, a thiophene compound, and a thiophene derivative.
In particular, the stilbene sulfonate compounds represented by the following formulas (1) to (3) are each anionic and water-soluble, are easy to handle, and are excellent even when added in a relatively small amount. It is a preferred fluorescent whitening agent because of its high fluorescent whitening effect.
[0056]
(Equation 1)

[0057]
[In the formula (1), the symbol M is hydrogen, an alkali metal, or any cation represented by ammonium and an amine ion, X and Y are mutually independent substituents, ₂ , N (C ₂ H ₄ OH) ₂ , N (CH ₂ CH (OH) CH ₃ ) ₂ , Or NR ¹ R ² (R ¹ And R ² Is hydrogen or a hydrocarbon group having 1 to 20 carbon atoms. )). ]
[0058]
[Equation 2]

[0059]
[In the formula (2), the symbols X and Y are mutually independent substituents, ₂ M (symbol M is hydrogen, an alkali metal, or any cation represented by ammonium and amine ions), NH ₂ , N (C ₂ H ₄ OH) ₂ , N (CH ₂ CH (OH) CH ₃ ) ₂ , Or NR ¹ R ² (R ¹ And R ² Is hydrogen or a hydrocarbon group having 1 to 20 carbon atoms. )). ]
[0060]
[Equation 3]

[0061]
[In the formula (3), the symbol X is NH ₂ , N (C ₂ H ₄ OH) ₂ , N (CH ₂ CH (OH) CH ₃ ) ₂ , Or NR ¹ R ² (R ¹ And R ² Is hydrogen or a hydrocarbon group having 1 to 20 carbon atoms. )). ]
[0062]
(2) Density
Further, the density of the optical brightener is set to 0.9 to 2.0 g / cm. ³ (Measurement temperature: 20 ° C., the same applies hereinafter).
The reason for this is that if the density of such a fluorescent whitening agent is out of such a range, it may be difficult to uniformly mix it in the lightweight clay. Therefore, the density of the optical brightener is adjusted to 1.0 to 1.6 g / cm. ³ Is more preferably within a range of 1.1 to 1.4 g / cm. ³ It is more preferable to set the value within the range.
[0063]
(3) Viscosity
The viscosity of the fluorescent whitening agent is preferably set to a value within the range of 5 to 1,000 mPa · s (measuring temperature: 20 ° C., the same applies hereinafter).
The reason for this is that if the viscosity of such a fluorescent whitening agent is less than 5 mPa · s, it may be difficult to mix it uniformly in lightweight clay. On the other hand, if the viscosity of the fluorescent whitening agent exceeds 1,000 mPa · s, not only coagulation and handling becomes difficult, but also it may be difficult to mix uniformly in the lightweight clay.
Therefore, the viscosity of the fluorescent whitening agent is more preferably set to a value in the range of 10 to 500 mPa · s, and still more preferably to a value in the range of 30 to 200 mPa · s.
[0064]
(4) pH
Further, the pH of the fluorescent whitening agent is preferably set to a value within the range of 7.1 to 10. The reason for this is that if the pH of the optical brightener is less than 7.1, the lightweight clay may be excessively gelled and the storage stability may be poor. On the other hand, if the pH of the fluorescent whitening agent exceeds 10, handling may be difficult.
Therefore, the pH of the fluorescent whitening agent is more preferably set to a value within the range of 7.5 to 9.5, and even more preferably to a value within the range of 8 to 9.
[0065]
(5) Addition amount
Further, it is preferable that the addition amount of the fluorescent whitening agent is a value within the range of 0.001 to 5% by weight based on the total amount.
The reason for this is that if the amount of the fluorescent whitening agent is less than 0.001% by weight, the effect of adding the fluorescent whitening agent is not exhibited, and it may be difficult to adjust the L value of the lightweight clay. On the other hand, if the amount of the fluorescent whitening agent exceeds 5% by weight, the L value of the lightweight clay is saturated, and the fluorescent whitening agent may bleed to the outside.
Therefore, the addition amount of the fluorescent whitening agent is more preferably set to a value within the range of 0.01 to 3% by weight, and more preferably to a value within the range of 0.05 to 1% by weight, based on the total amount. Is more preferable.
[0066]
It is also preferable to determine the amount of the fluorescent brightener to be added based on the organic hollow microspheres. That is, when the addition amount of the organic hollow microspheres is F1 and the addition amount of the fluorescent whitening agent is F2, the value of F1 / F2 is preferably set to a value within the range of 1 to 100.
The reason for this is that when the value of F1 / F2 is less than 1, the L value of the lightweight clay is saturated, and it may be difficult to reduce the weight of the lightweight clay. On the other hand, if the value of F1 / F2 exceeds 100, it may be difficult to adjust the L value of the lightweight clay.
Therefore, it is more preferable to set the value of F1 / F2 to a value in the range of 2 to 50, and more preferably to a value in the range of 5 to 30.
[0067]
7. Gelling agent
(1) Type
In addition, it is preferable to add a gelling agent to a main agent such as polyvinyl alcohol. By adding the gelling agent in this way, the handleability and moldability of the lightweight clay can be significantly improved.
Examples of such a gelling agent include boric acid, borax, congo red, resorcinol, catechol, phloroglucinol, pansan, gallic acid, chromic acid (trivalent), dichromic acid, titanic acid, and vanadic acid. A combination of two or more types may be mentioned. Of these, boric acid and borax are preferred gelling agents, particularly because the control of gelation of polyvinyl alcohol is easy.
[0068]
(2) Addition amount
Further, the addition amount of the gelling agent is preferably determined in consideration of the handleability and moldability of the lightweight clay, for example, with respect to 100 parts by weight of polyvinyl alcohol, in the range of 0.01 to 10 parts by weight. It is preferable to use a value.
This is because if the amount of the gelling agent is less than 0.01 part by weight, the effect of the addition may not be exhibited. On the other hand, if the amount of the gelling agent exceeds 10 parts by weight, it may be difficult to control the gelation of polyvinyl alcohol in the lightweight clay.
Therefore, the amount of the gelling agent to be added is more preferably in the range of 0.05 to 5 parts by weight, and more preferably in the range of 0.1 to 1 part by weight, based on 100 parts by weight of polyvinyl alcohol. More preferably, it is set to a value.
[0069]
8. Filler
(1) Type
Further, it is preferable to add an organic filler or an inorganic filler to the lightweight clay. The reason for this is that by adding such a filler, it is possible to obtain a lightweight clay that is more excellent in the formability and lightness of the lightweight clay or the whiteness.
Examples of such a filler include polymethyl methacrylate, polyethyl acrylate, polystyrene, styrene-acrylonitrile copolymer, styrene-vinyl acetate copolymer, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyethylene, and ethylene- Acrylic acid copolymer, polypropylene, polyvinylidene chloride, vinylidene chloride-acrylonitrile copolymer, phenol resin, guanamine resin, urea resin, calcium carbonate, talc, titanium oxide, silica, mica, zirconium, alumina, chromium oxide, tin oxide , Lead oxide, indium oxide, carbon, glass, aramid fiber and the like.
In particular, talc is inexpensive and easy to handle due to its appropriate average particle size, and is a preferable filler in adjusting the formability and lightness of lightweight clay.
[0070]
(2) Addition amount
In addition, when such a filler is added, the addition amount is preferably set to a value within the range of 0.1 to 20% by weight, when the total amount of the lightweight clay is 100% by weight.
The reason for this is that if the amount of the filler added is less than 0.1% by weight, the effect of addition may not be exhibited. On the other hand, when the amount of the filler is 20 parts by weight or more, the formability and the lightness of the lightweight clay may be deteriorated.
Therefore, when the total amount of the lightweight clay is 100% by weight, the amount of the filler is more preferably in the range of 0.5 to 15% by weight, and more preferably in the range of 1 to 10% by weight. More preferably, it is set to a value.
[0071]
9. Whiteness
(1) Whiteness (WL)
Further, the whiteness (WL) of the lightweight clay measured according to JIS L0803 is set to a value of 70 or more.
The reason for this is that when the whiteness (WL) of such a lightweight clay is less than 70, the aesthetic appearance is reduced, and when a pigment is added, the clay becomes turbid and the color development is significantly reduced. . However, if the value of the whiteness (WL) is too high, the types of constituent materials that can be used may be excessively limited.
Therefore, the whiteness (WL) of such organic hollow microspheres is preferably set to a value in the range of 70 to 99.9, and more preferably to a value in the range of 80 to 99.
[0072]
Here, the relationship between the whiteness (WL) of the lightweight clay and the evaluation result of the coloring property will be described with reference to the characteristic diagrams shown in FIGS. 4 and 5. In FIG. 4, the abscissa indicates the value of the whiteness (WL) of the lightweight clay, and the ordinate indicates the evaluation result (relative value) of the coloring property. The characteristic curve of a black circle (●) is the case where 0.02% by weight of the blue dye is added, and the characteristic curve of the black triangle (▲) is the case where 0.1% by weight of the yellow dye is added. The evaluation results (relative values) of the coloring properties were as follows: evaluation ◎ shown in Example 1 was evaluated at evaluation point 5, ○ was evaluated at evaluation point 4, Δ was evaluated at evaluation point 2, × was evaluation point 1, and XX was evaluation point 0. It was done.
From the characteristic curves shown in FIG. 4, in each of the lightweight clays to which the blue pigment and the yellow pigment are added, the higher the whiteness (WL), the higher the color development evaluation point tends to be. Particularly, the whiteness (WL) It is understood that a good evaluation score can be obtained if is 50 or more.
In FIG. 5, the abscissa indicates the addition amount (% by weight) of the fluorescent whitening agent, and the ordinate indicates the evaluation results of the color developability when the blue pigment was added at 0.02% by weight (relative). Value). A solid circle (●) indicates a case where the whiteness (WL) of the lightweight clay is 50 or more (WL = 60), and a solid triangle (▲) indicates a case where the whiteness (WL) of the lightweight clay is less than 50 ( WL = 0). As can be understood from the results, when the whiteness (WL) of the lightweight clay is 50 or more, by adding about 0.05 to 0.1% by weight of a fluorescent whitening agent, three or more evaluation points are obtained. Is obtained. On the other hand, when the whiteness (WL) of the lightweight clay is less than 50, the evaluation score is 1 even when many fluorescent whitening agents of about 0.3 to 0.5% by weight are added. Stay below low.
Therefore, it is understood that by setting the whiteness (WL) of the lightweight clay to a value of 50 or more, excellent color developability can be obtained even when a small amount of a fluorescent whitening agent is added.
[0073]
(2) Whiteness (WB), whiteness (WL), luminosity (L value)
As an index of whiteness similar to whiteness (WL) measured according to JIS L0803, whiteness (WB) based on blue reflectance, whiteness (WH) based on a Hunter method, and visual luminosity ( L value).
These whitenesses are values measured independently of the whiteness (WL) in accordance with JIS L 0803. When the whiteness of lightweight clay is represented by these whitenesses, for example, the whiteness is determined by the blue reflectance. The whiteness (WB) is preferably a value within the range of 60 to 95. Similarly, in the case of whiteness (WH) by the Hunter method, the value is preferably in the range of 70 to 98, and in the case of visual luminosity (L value), the value is in the range of 80 to 99. Preferably, there is.
[0074]
10. Other additives
In lightweight clay, as additives, in addition to the above-mentioned additives, antifungal agents, antibacterial agents, antioxidants, ultraviolet absorbers, oils, waxes, glycerin, thickeners, plasticizers, surfactants, It is also preferable to add one kind of organic solvent or the like or a combination of two or more kinds.
[0075]
11. Production method
(1) Mixing process
This is a step of uniformly mixing compounding raw materials such as organic hollow microspheres, a dye, a polar compound, a fiber, and water. For example, it is preferable to use a propeller mixer, a kneader, a planetary mixer, a three-roll mill, a ball mill, or the like so that these ingredients can be uniformly mixed and dispersed.
In particular, the organic hollow microspheres are light and easily broken during kneading, while dispersion tends to occur. Therefore, using a kneader, the number of rotations is 10 to 1,000 rpm, and the time is 1 to 60 minutes. It is preferable to carry out extrusion kneading under the conditions, and more preferable to carry out extrusion kneading under the conditions of a rotation speed of 30 to 300 rpm and a time of 10 to 30 minutes.
In addition, the pigment is also preliminarily dispersed in water or alcohol to prepare a solution so that the pigment can be uniformly mixed and dispersed, and an alkali agent or the like is added so that the solution does not aggregate, and the pH is adjusted to 7 or more. Is preferably adjusted to a value within the range of 8 to 10, more preferably to a value within the range of 8.5 to 10.
In addition, when mixing the compounding raw materials, it is preferable to maintain the temperature, for example, in the range of 30 to 70 ° C.
The reason for this is that if the mixing temperature is lower than 30 ° C., the compounded raw materials may not be uniformly mixed. On the other hand, if the mixing temperature is higher than 70 ° C., the obtained lightweight clay loses elongation and becomes brittle. This is because there are cases.
Therefore, it is more preferable to maintain the mixing temperature at the time of mixing the compounding raw materials at a temperature in the range of 35 to 60 ° C, and it is even more preferable to maintain the temperature in the range of 40 to 55 ° C.
[0076]
(2) Viscosity adjustment process
This is a step of adjusting the viscosity of the lightweight clay. By adding water, alcohol, or an organic solvent, the viscosity of the lightweight clay is reduced to, for example, 1 × 10 ³ ~ 1 × 10 ⁹ The value is preferably within a range of mPa · s (measuring temperature: 25 ° C., the same applies hereinafter). The reason is that the viscosity of such lightweight clay is 1 × 10 ³ When the value is less than mPa · s, the tackiness of the surface increases and the handleability may decrease, while the viscosity of the lightweight clay is 1 × 10 ⁹ If the viscosity exceeds mPa · s, the obtained lightweight clay loses elongation, becomes brittle, and on the contrary, the handleability may decrease. Therefore, the viscosity of such lightweight clay is 1 × 10 ⁴ ~ 1 × 10 ⁸ More preferably, the value is in the range of mPa · s. ⁵ ~ 1 × 10 ⁷ More preferably, the value is in the range of mPa · s.
[0077]
(3) Packaging process
It is preferable to provide a step of subdividing the produced lightweight clay and packaging it. That is, usually, lightweight clay contains a relatively large amount of water, alcohol, etc., so that the moisture content in the lightweight clay is maintained, and in order to maintain handleability, a moisture-proof material, for example, polyethylene or polypropylene. It is preferable to package with a plastic material.
However, in order to reduce the expansion problem due to degassing of the unfoamed organic hollow microspheres, it is preferable to provide ventilation holes in the packaging material or to configure the packaging material from a gas-permeable material.
In this case, in order to balance the maintenance of the water content in the lightweight clay and the reduction of the expansion problem, it is preferable to set the size of the vents to a value in the range of 0.01 to 100 μm, and 0.05 to 50 μm. Is more preferably set in the range of 0.1 to 20 μm, and still more preferably set in the range of 0.1 to 20 μm.
[0078]
【Example】
[Example 1]
(1) Creation of lightweight clay
After the following compounding materials were placed in a kneader having a capacity of 100 liters, the kneader was rotated at a rotation speed of 40 rpm to produce a lightweight clay.

In addition, after mixing the compounding materials uniformly, talc (density: 2.82 g / cm ³ ) Was added at a ratio of 8% by weight to obtain a lightweight clay of Example 1. The whiteness of the lightweight clay was measured using a color meter TC-1800MK2 (manufactured by Tokyo Denshoku Co., Ltd.). In this case, the lightweight clay was prepared by removing the yellow pigment from the above composition.
[0079]
(2) Evaluation of lightweight clay
With respect to the obtained lightweight clay, evaluations of the following shaping properties (film forming properties), lightweight properties, coloring properties, stickiness and swelling properties (storage properties) were respectively performed. Table 1 shows the obtained results (average evaluation of n = 5).
[0080]
▲ 1 ▼ Moldability
The formability (film forming property) of the lightweight clay was evaluated according to the following criteria. In addition, if the evaluation of (circle) or more is obtained, it can be said that it has the moldability suitable for lightweight clay.
A: A film having a thickness of 0.2 mm or less can be formed using a roll.
：: A film having a thickness of 1 mm or less can be formed using a roll.
Δ: A film having a thickness of 5 mm or less can be formed using a roll.
X: Even if a roll is used, a film having a thickness of 5 mm or less cannot be formed.
[0081]
(2) Lightweight
The lightness of the lightweight clay was evaluated according to the following criteria. In addition, if the evaluation of ○ or more is obtained, it can be said that the clay has sufficient lightness as a lightweight clay.
A: Density is 0.3 g / cm ³ The following values.
：: density 0.5 g / cm ³ The following values.
Δ: Density 0.7 g / cm ³ The following values.
×: Density 0.7 g / cm ³ Is greater than
[0082]
(3) Color development
The color development of the lightweight clay was evaluated according to the following criteria. In addition, if the evaluation of ○ or more is obtained, it can be said that the light clay has good color developability.
：: Clear color with a sense of transparency.
：: Vivid color.
Δ: Slightly clear color.
X: Unclear color.
XX: cloudy, different color from the added dye.
[0083]
4) Stickiness
The tackiness of the lightweight clay was evaluated by the following criteria by touching it. In addition, if the evaluation of ○ or more is obtained, it can be said that the tackiness of the lightweight clay is good.
A: Almost no stickiness.
：: There is some stickiness.
Δ: Notable stickiness, but light weight clay does not transfer to fingers.
X: There is remarkable stickiness, and lightweight clay is transferred to the finger.
[0084]
(5) Expandability
100 g of lightweight clay was formed into a rectangle, and the periphery thereof was wrapped with a 100 μm-thick polyethylene film. After being left in an oven at 40 ° C. for one week in this state, the volume was measured, and the swelling property (storage property) was evaluated based on the following criteria in relation to the initial volume. In addition, if the evaluation of (circle) or more is obtained, it can be said that it has the expandability (storage property) suitable for lightweight clay.
A: Volume change rate is less than 3%.
：: Volume change rate is less than 10%.
Δ: Volume change rate is less than 30%.
X: Volume change rate is 30% or more.
[0085]
▲ 6 ▼ Weather resistance
The weather resistance of the lightweight clay was evaluated according to the following criteria. In addition, if the evaluation of 有 し or more is obtained, it can be said that it has weather resistance suitable for lightweight clay.
◎: UV light at 1000 mJ / cm ² It does not discolor when irradiated.
：: UV light at 500 mJ / cm ² Almost no discoloration upon irradiation.
Δ: UV rays at 500 mJ / cm ² Slightly discolors when irradiated.
×: UV rays of 500 mJ / cm ² When irradiated, the color changes significantly.
[0086]
7) Bleed resistance
The bleed resistance of the pigment in the lightweight clay was evaluated according to the following criteria. In addition, if an evaluation of ○ or more is obtained, it can be said that the dye pigment has bleed resistance suitable for lightweight clay.
：: The pigment does not adhere to the hand even when the lightweight clay is kneaded by hand for 5 minutes.
：: Even when the lightweight clay is kneaded by hand for 5 minutes, almost no pigment is attached to the hand.
Δ: When the lightweight clay is kneaded by hand for 5 minutes, the pigment is slightly attached to the hand.
×: When the lightweight clay is kneaded with the hand for 5 minutes, the pigment is remarkably adhered to the hand.
[0087]
[Examples 2 to 4 and Comparative Examples 1 to 3]
As shown in Table 1, the types of organic hollow microspheres (in Example 4 and Comparative Examples 1 to 3, the average particle diameter was 100 μm, the whiteness (WL) and the L value were each less than 50, and the acidic brown organic hollow microspheres were different. ), The average particle size and the amount of addition were changed, and the amounts of fiber and water added were changed to produce a lightweight clay in the same manner as in Example 1. The obtained lightweight clay was evaluated in the same manner as in Example 1. Table 1 shows the obtained results.
As can be easily understood from the results, it was found that when the added amount of the organic hollow microspheres exceeded 6% by weight, the evaluation of the shaping property, the coloring property, and the swelling property of the lightweight clay was remarkably reduced.
On the other hand, even if the amount of the fiber material added is less than 10% by weight, it has been found that, unlike the conventional knowledge, it is possible to sufficiently reduce the weight of the lightweight clay.
Further, it has been found that, unlike the conventional knowledge, even when the amount of water added exceeds 60% by weight, the tackiness of the lightweight clay can be sufficiently adjusted to an appropriate value.
[0088]
[Table 1]

[0089]
[Examples 5 to 8, and Comparative Examples 1 to 3]
As shown in Table 1, a fluorescent brightener (anionic stilbene sulfonate compound, property: liquid, density: 1.22 g / cm) based on the total amount (100% by weight) ^Three , PH: 8-9, viscosity: 30-50 mPa · s (measuring temperature: 20 ° C.)), except that the mixing ratio of CMC and PVA was changed, and a lightweight clay was prepared in the same manner as in Example 1. . Next, the obtained lightweight clay was evaluated in the same manner as in Example 1. Table 2 shows the obtained results. As can be easily understood from the results, the whiteness (WL) of the obtained lightweight clay can be easily adjusted to a value of 70 or more by adding a predetermined amount of the fluorescent whitening agent. Also, by adding a predetermined amount of the fluorescent whitening agent, the weather resistance and the color development can be remarkably improved. Therefore, even if the molded lightweight clay is left for a long time in the place where the sun hits the window, it is expected that excellent color developability is maintained.
[0090]
[Table 2]

[0091]
[Examples 5 to 8, and Comparative Examples 1 to 3]
According to the lightweight clay of the present invention, the average particle diameter of the organic hollow microspheres is set to a value within the range of 15 to 150 μm, and the amount of the organic hollow microspheres added is 0.1 to By setting the value within a range of 6% by weight and setting the whiteness (WL) of the lightweight clay measured in accordance with JIS L 0803 to a value of 70 or more, the coloring property, the formability, and the lightness are improved. Excellent, and even when stored for a long time after being covered with a packaging material, or when the ambient temperature rises in the summer or the like and the temperature becomes high, the problem of expansion is eliminated and excellent storage properties can be obtained. At the same time, it has become possible to provide a lightweight clay whose production cost is low.
Further, in the lightweight clay of the present invention, by setting the mixing ratio of CMC and PVA to a value within the range of 100: 40 to 100: 500, molding into a predetermined shape is easy and difficult with the conventional lightweight clay. It has become possible to reduce the film thickness, for example, to a film having a thickness of 0.1 mm or less, and to use it for decorative materials and origami.
Further, in the lightweight clay of the present invention, by adding a predetermined amount of a pigment pigment having an average particle size of 0.05 to 0.2 μm, and a standard deviation in the particle size distribution to a value of 0.05 μm or less, In addition to having extremely excellent coloring properties, excellent light fastness and bleeding resistance of dye pigments can be obtained.
Furthermore, according to the method for producing a lightweight clay of the present invention, while using the organic hollow microspheres having an average particle size within a range of 15 to 150 μm, the organic hollow microspheres are kneaded using a kneader, and The addition amount is set to a value within the range of 0.1 to 6% by weight based on the total amount, and the whiteness (WL) of the lightweight clay measured according to JIS L 0803 is set to a value of 70 or more. By doing so, it became possible to provide inexpensively a lightweight clay excellent in coloring property, formability, and lightness, and also excellent in storage property (expandability).
[0092]
[Brief description of the drawings]
FIG. 1 is a characteristic diagram showing the relationship between the amount of organic hollow microspheres added to a lightweight clay and the lightness and formability of the lightweight clay.
FIG. 2 is a characteristic diagram showing the relationship between the amount of organic hollow microspheres added to lightweight clay and the results of swelling evaluation.
FIG. 3 is a characteristic diagram showing the relationship between the amount of organic hollow microspheres added to lightweight clay and the production cost ratio.
FIG. 4 is a characteristic diagram showing a relationship between whiteness (WL) and coloring properties in lightweight clay.
FIG. 5 is a characteristic diagram showing the relationship between the amount of a fluorescent whitening agent added to a lightweight clay and the color developing property.
FIG. 6 (a) is a diagram provided to explain the relationship between the average particle size of the pigment in the lightweight clay of the present invention and light transmittance (color-forming property).
FIG. 3B is a diagram provided to explain the relationship between the average particle size of the pigment in conventional lightweight clay and light transmission (coloring).
FIG. 7A is a diagram provided to explain the relationship between the amount of a pigment added to the lightweight clay of the present invention and light transmittance (color-forming property).
(B) A diagram provided to explain the relationship between the amount of a pigment added in a conventional lightweight clay and light transmittance (color-forming property).
[0093]
[Explanation of symbols]
10: Dye pigment
12: Organic hollow microsphere
14, 16, 24, 26: Light

Claims (16)

In the lightweight clay containing the organic hollow microspheres and the binder resin, the average particle size of the organic hollow microspheres is set to a value in the range of 15 to 150 μm, and the amount of the organic hollow microspheres added to the total amount is reduced. A lightweight clay having a value of 6% by weight or less and a whiteness (WL) of the lightweight clay measured in accordance with JIS L 0803 of 70 or more. The lightweight clay according to claim 1, wherein whiteness (WL) of the organic hollow microspheres measured according to JIS L0803 is a value of 50 or more. The fluorescent whitening agent is contained, and the amount of the fluorescent whitening agent is set to a value within a range of 0.001 to 5% by weight based on the total amount. Lightweight clay. The lightweight clay according to claim 3, wherein the surface of the organic hollow microsphere is surface-treated with the fluorescent whitening agent. The value of F1 / F2 is set to a value within a range of 1 to 100 when the addition amount of the organic hollow microspheres is F1 and the addition amount of the fluorescent whitening agent is F2. The lightweight clay according to 3 or 4. When the density of the constituent material other than the organic hollow microspheres is less than 0.5 to 0.8 g / cm ² , the amount of the organic hollow microspheres to be added is 0.1 to 3 wt. %, And when the density of the constituent materials other than the organic hollow microspheres is 0.8 to 5 g / cm ² , the amount of the organic hollow microspheres to be added to the total amount is The lightweight clay according to any one of claims 1 to 5, wherein the value is in the range of 0.1 to 6% by weight. The lightweight clay further contains, as the binder resin, a hydroxyl group-containing compound and a carboxyl group-containing compound, or one of the polar compounds, and the amount of the polar compound to be added is 0.1 to The lightweight clay according to any one of claims 1 to 6, wherein the value is within a range of 30% by weight. When the hydroxyl group-containing compound and the carboxyl group-containing compound contain carboxymethylcellulose and polyvinyl alcohol and do not contain the fluorescent whitening agent, the mixing ratio (weight ratio) of the carboxymethylcellulose and polyvinyl alcohol is 100: 40 to When the fluorescent whitening agent is contained, the mixing ratio (weight ratio) of the carboxymethyl cellulose and polyvinyl alcohol is set to a value within the range of 100: 550 to 100: 2,000. The lightweight clay according to any one of claims 1 to 7, characterized in that: The light-weight clay further contains fibers, and the amount of the fibers to be added is set to a value within a range of less than 1 to 10% by weight based on the total amount. The lightweight clay according to claim 1. The said lightweight clay further contains water, The addition amount of the said water is made into the value in the range of 61-85 weight% with respect to the whole quantity, The any one of Claims 1-9 characterized by the above-mentioned. The lightweight clay according to claim 1. The said lightweight clay further contains a pigment | dye, The addition amount of the said pigment | dye is made into the value in the range of less than 0.01-10 weight% with respect to the whole quantity. The lightweight clay according to any one of the above. The light weight according to claim 11, wherein the average particle size of the dye is set to a value within a range of 0.05 to 0.2 µm, and the standard deviation in the particle size distribution is set to a value of 0.05 µm or less. clay. The ratio of D2 / D1 is a value within the range of 10 to 50,000, where D1 is the average particle size of the dye and D2 is the average particle size of the organic hollow microspheres. Item 13. The lightweight clay according to item 11 or 12. The said lightweight clay further contains a filler, The addition amount of the said filler is made into the value in the range of less than 0.1-20 weight% with respect to the whole quantity, The Claims 1-13 characterized by the above-mentioned. The lightweight clay according to any one of the above. The lightweight clay further contains inorganic hollow microspheres, and the amount of the inorganic hollow microspheres is set to a value within the range of 0.01 to 10% by weight based on the total amount. The lightweight clay according to any one of claims 1 to 14. In the method for producing a lightweight clay containing organic hollow microspheres and a binder resin, the addition amount of the organic hollow microspheres having an average particle diameter in a range of 15 to 150 μm is 6% by weight or less based on the total amount. And kneading the organic hollow microspheres and the binder resin using a kneader, and setting the whiteness (WL) of the lightweight clay measured according to JIS L 0803 to a value of 70 or more. To make lightweight clay.

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