JP3564082B2 - Low molecular weight (meth) acrylic acid (salt) -based polymer, its production method and use - Google Patents

Description

【０１０７】
（ハーゼンの測定方法）
▲１▼ 重合体水溶液のハーゼンは、分光式色差計ＳＥ−２０００（日本電色工業製）を用いて測定した。
【０１０８】
（カルシウムイオン捕捉能）
▲１▼ まず、検量線用カルシウムイオン標準液として、塩化カルシウム２水和物を用いて、０．０１ｍｏｌ／ｌ、０．００１ｍｏｌ／ｌ、０．０００１ｍｏｌ／ｌの水溶液をそれぞれ５０ｇ調製し、４．８％ＮａＯＨ水溶液でｐＨを９〜１１の範囲に調整し、さらに４ｍｏｌ／ｌの塩化カリウム水溶液（以下４Ｍ−ＫＣｌ水溶液と略す）を１ｍｌ添加した後、マグネチックスターラーを用いて十分に攪拌して検量線用サンプル液を作成した。また、試験用カルシウムイオン標準液として、同じく塩化カルシウム２水和物を用いて、０．００１２ｍｏｌ／ｌの水溶液を必要量（１サンプルにつき５０ｇ使用）調製した。
【０１０９】
▲２▼ 次いで、１００ｃｃビーカーに試験サンプル（重合体）を固形分換算で１０ｍｇ秤量し、▲１▼で調製した試験用のカルシウムイオン標準液５０ｇを添加しマグネチックスターラーを用いて十分に攪拌した。さらに、検量線用サンプル液と同様に、４．８％ＮａＯＨ水溶液でｐＨを９〜１１の範囲に調整し、４Ｍ−ＫＣｌ水溶液を１ｍｌ添加して試験用サンプル液を作成した。
【０１１０】
▲３▼ このようにして作成した検量線用サンプル液、試験用サンプル液を、オリオン社製イオンアナライザーＥＡ９２０を用いて、オリオン社製カルシウムイオン電極９３−２０により測定を行った。
【０１１１】
▲４▼ 検量線及び試験用のサンプル液の測定値から、サンプル（重合体）が捕捉したカルシウムイオン量を計算により求め、重合体固形分１ｇ当りの捕捉量を炭酸カルシウム換算のｇ数で表わし、この値をカルシウムイオン捕捉能値とした。
【０１１２】
（高硬度水下におけるクレー分散能）
▲１▼ まず、グリシン６７．５６ｇ、塩化ナトリウム５２．６ｇ、１ｍｏｌ／ｌのＮａＯＨ水溶液６０ｍｌにイオン交換水を加えて６００ｇとしたグリシン緩衝溶液を調製した。
【０１１３】
▲２▼ 塩化カルシウム２水和物を０．３２６８ｇ、▲１▼の調製液６０ｇを取って、純水を加えて１０００ｇとし、分散液を調製した。また、固形分換算で０．１％の重合体水溶液を調製した。
【０１１４】
▲３▼ 約３０ｃｃの実験に用いる一般的な試験管に、ＪＩＳ試験用粉体Ｉ，８種（関東ローム，微粒：日本粉体工業技術協会）のクレー０．３ｇを入れ、▲２▼の分散液２７ｇ、重合体水溶液３ｇを添加した。この時、試験液のカルシウム濃度は炭酸カルシウム換算２００ｐｐｍとなっている。
【０１１５】
▲４▼ 試験管をパラフィルムで密封した後、クレーが全体に分散するように軽く振り、さらに上下に２０回振った。この試験管を直射日光の当たらないところに２０時間静置した後、分散液の上澄みをホールピペットで５ｍｌ採取した。
【０１１６】
▲５▼ この液をＵＶ分光器を用いて、波長３８０ｎｍの条件で、１ｃｍのセルで吸光度（ＡＢＳ）を測定し、この値を高硬度水下におけるクレー分散能値とした。
【０１１７】
次に、本発明の具体的な実施例について説明する。
【０１１８】
（実施例１−１）
温度計、攪拌機、及び還流冷却器を備えた容量２．５リットルのＳＵＳ製セパラブルフラスコにイオン交換水（以下純水と記す）１９３．０ｇを初期仕込し、攪拌下、該純水を沸点還流状態まで昇温した。次いで、攪拌下、還流状態を維持しながら、８０％アクリル酸水溶液（以下８０％ＡＡと記す）４５０．０ｇを重合開始から１８０分間に渡って、３５％過酸化水素水溶液１１４．３ｇ（以下３５％Ｈ_２Ｏ_２と記す）を重合開始から６０分間に渡って、１５％過硫酸ナトリウム水溶液（以下１５％ＮａＰＳと略す）１３３．３ｇを重合開始から１９０分間に渡って、４８％水酸化ナトリウム水溶液（以下４８％ＮａＯＨと記す）３３３．３ｇを重合開始から１８０分に渡って、それぞれ別々の滴下ノズルから連続的に均一速度で滴下した。さらに全ての滴下終了後２０分間に渡って、沸点還流状態を維持して、重合を完了した。
【０１１９】
重合終了後、沸点還流状態を３０分間維持したまま４８％ＮａＯＨ ６２．５ｇを攪拌下、反応溶液に徐々に滴下して中和した。このようにして、固形分濃度３９．５％、最終中和度９５％のポリアクリル酸ナトリウム１−１（以下、重合体１−１とする）を得た。得られた重合体１−１の重量平均分子量Ｍｗ、過酸化水素含有量、ハーゼン、カルシウムイオン捕捉能、および、クレー分散能を測定した。その結果を表１に示す。
【０１２０】
（実施例１−２）
実施例１−１において３５％Ｈ_２Ｏ_２添加量を５７．１ｇとした以外は、同様に重合を行った。その後、沸点還流状態を３０分間維持したまま４８％ＮａＯＨ ６２．５ｇを攪拌下、反応溶液に徐々に滴下して中和した。このようにして、固形分濃度４１．５％、最終中和度９５％のポリアクリル酸ナトリウム１−２（以下、重合体１−２とする）を得た。得られた重合体１−２の重量平均分子量Ｍｗ、過酸化水素含有量、およびハーゼン、カルシウムイオン捕捉能、および、クレー分散能を測定した。その結果を表１に示す。
【０１２１】
（実施例１−３）
実施例１−２において３５％Ｈ_２Ｏ_２を重合開始から９０分にわたって連続的に均一速度で滴下した以外同様に重合を行った。その後、沸点還流状態を３０分間維持したまま４８％ＮａＯＨ ６２．５ｇを攪拌下、反応溶液に徐々に滴下して中和した。このようにして、固形分濃度４１．７％、最終中和度９５％のポリアクリル酸ナトリウム１−３（以下、重合体１−３とする）を得た。得られた重合体１−３の重量平均分子量Ｍｗ、過酸化水素含有量、ハーゼン、カルシウムイオン捕捉能、および、クレー分散能を測定した。その結果を表１に示す。
【０１２２】
（実施例１−４）
実施例１−１において３５％Ｈ_２Ｏ_２滴下量を８５．７ｇとし、重合開始から１５０分にわたって連続的に均一速度で滴下した以外は同様に重合を行った。その後、沸点還流状態を３０分間維持したまま４８％ＮａＯＨ ６２．５ｇを攪拌下、反応溶液に徐々に滴下して中和した。このようにして、固形分濃度４０．５％、最終中和度９５％のポリアクリル酸ナトリウム１−４（以下、重合体１−４とする）を得た。得られた重合体１−４の重量平均分子量Ｍｗ、過酸化水素含有量、ハーゼン、カルシウムイオン捕捉能、および、クレー分散能を測定した。その結果を表１に示す。
【０１２３】
（実施例１−５）
実施例１−４において３５％Ｈ_２Ｏ_２滴下量を６８．６ｇとした以外は同様に重合を行った。その後、沸点還流状態を３０分間維持したまま４８％ＮａＯＨ ６２．５ｇを攪拌下、反応溶液に徐々に滴下して中和した。このようにして、固形分濃度４１．０％、最終中和度９５％のポリアクリル酸ナトリウム１−５（以下、重合体１−５とする）を得た。得られた重合体１−５の重量平均分子量Ｍｗ、過酸化水素含有量、ハーゼン、カルシウムイオン捕捉能、および、クレー分散能を測定した。その結果を表１に示す。
【０１２４】
（実施例１−６）
実施例１−５において４８％ＮａＯＨ滴下量を３７５．０ｇとした以外は同様に重合を行った。その後、沸点還流状態を３０分間維持したまま４８％ＮａＯＨ２０．８ｇを攪拌下、反応溶液に徐々に滴下して中和した。このようにして、固形分濃度４１．３％、最終中和度９５％のポリアクリル酸ナトリウム１−６（以下、重合体１−６とする）を得た。得られた重合体１−６の重量平均分子量Ｍｗ、過酸化水素含有量、ハーゼン、カルシウムイオン捕捉能、および、クレー分散能を測定した。その結果を表１に示す。
【０１２５】
（実施例１−７）
実施例１−６において３５％Ｈ_２Ｏ_２滴下量を１１４．３ｇとした以外は同様に重合を行った。その後、沸点還流状態を３０分間維持したまま４８％ＮａＯＨ ２０．８ｇを攪拌下、反応溶液に徐々に滴下して中和した。このようにして、固形分濃度３９．９％、最終中和度９５％のポリアクリル酸ナトリウム１−７（以下、重合体１−７とする）を得た。得られた重合体１−７の重量平均分子量Ｍｗ、過酸化水素含有量、ハーゼン、カルシウムイオン捕捉能、および、クレー分散能を測定した。その結果を表１に示す。
【０１２６】
（実施例１−８）
実施例１−４において１５％ＮａＰＳ滴下量を８３．３ｇ、および４８％ＮａＯＨ滴下量を３７５．０ｇとした以外は同様に重合を行った。その後、沸点還流状態を３０分間維持したまま４８％ＮａＯＨ ２０．８ｇを攪拌下、反応溶液に徐々に滴下して中和した。このようにして、固形分濃度４２．１％、最終中和度９５％のポリアクリル酸ナトリウム１−８（以下、重合体１−８とする）を得た。得られた重合体１−８の重量平均分子量Ｍｗ、過酸化水素含有量、ハーゼン、カルシウムイオン捕捉能、および、クレー分散能を測定した。その結果を表１に示す。
【０１２７】
（実施例１−９）
温度計、攪拌機、及び還流冷却器を備えた容量２．５リットルのＳＵＳ製セパラブルフラスコに純水１９５．９ｇを初期仕込し、攪拌下、該純水を沸点還流状態まで昇温した。次いで、攪拌下、還流状態を維持しながら、８０％ＡＡ ２６０．９ｇを重合開始５分後から１７５分間に渡って、３７％アクリル酸ナトリウム水溶液（以下３７％ＳＡと記す）５３３．８ｇを重合開始３０分後から１５０分間に渡って、３５％Ｈ_２Ｏ_２ ５４．９ｇを重合開始から１５０分間に渡って、１５％ＮａＰＳ １０６．７ｇを重合開始から１９０分間に渡って、４８％ＮａＯＨ ２００．０ｇを重合開始５分後から１８０分に渡って、それぞれ別々の滴下ノズルから連続的に均一速度で滴下して重合を完了した。
【０１２８】
重合終了後、沸点還流状態を３０分間維持したまま４８％ＮａＯＨ ２０．８ｇを攪拌下、反応溶液に徐々に滴下して中和した。さらに沸点還流状態を６０分間維持しながら反応溶液を濃縮し、固形分濃度４０．０％、最終中和度９５％のポリアクリル酸ナトリウム１−９（以下、重合体１−９とする）を得た。得られた重合体１−９の重量平均分子量Ｍｗ、過酸化水素含有量、ハーゼン、カルシウムイオン捕捉能、および、クレー分散能を測定した。その結果を表１に示す。
【０１２９】
（実施例１−１０）
温度計、攪拌機、及び還流冷却器を備えた容量２．５リットルのＳＵＳ製セパラブルフラスコに純水２３１．３ｇを初期仕込し、攪拌下、該純水を沸点還流状態まで昇温した。次いで、攪拌下、還流状態を維持しながら、８０％ＡＡ ４５０．０ｇを重合開始５分後から２３５分間に渡って、３５％Ｈ_２Ｏ_２ ６１．１ｇを重合開始から１８０分間に渡って、１５％ＮａＰＳ １０６．７ｇを重合開始から２５０分間に渡って、４８％ＮａＯＨ ３７５．０ｇを重合開始５分後から２３５分に渡って、それぞれ別々の滴下ノズルから連続的に均一速度で滴下して重合を完了した。
【０１３０】
重合終了後、沸点還流状態を３０分間維持したまま４８％ＮａＯＨ ２０．８ｇを攪拌下、反応溶液に徐々に滴下して中和した。さらに沸点還流状態を９０分間維持し、固形分濃度４０．１％、最終中和度９５％のポリアクリル酸ナトリウム１−１０（以下、重合体１−１０とする）を得た。得られた重合体１−１０の重量平均分子量Ｍｗ、過酸化水素含有量、ハーゼン、カルシウムイオン捕捉能、および、クレー分散能を測定した。その結果を表１に示す。
（実施例１−１１）
温度計、攪拌機、及び還流冷却器を備えた容量２．５リットルのＳＵＳ製セパラブルフラスコに純水２７２．３ｇを初期仕込し、攪拌下、該純水を沸点還流状態まで昇温した。次いで、攪拌下、還流状態を維持しながら、８０％ＡＡ ４５０．０ｇを重合開始から２４０分間に渡って、３５％Ｈ_２Ｏ_２ ５７．２ｇを重合開始１５分後から１８５分間に渡って、１５％ＮａＰＳ ８３．３ｇを重合開始から２５０分間に渡って、４８％ＮａＯＨ ３７５．０ｇを重合開始から２４０分に渡って、それぞれ別々の滴下ノズルから連続的に均一速度で滴下して重合を完了した。
【０１３１】
重合終了後、沸点還流状態を３０分間維持したまま４８％ＮａＯＨ ２５．０ｇを攪拌下、反応溶液に徐々に滴下して中和した。さらに沸点還流状態を９０分間維持し、固形分濃度３９．６％、最終中和度９６％のポリアクリル酸ナトリウム１−１１（以下、重合体１−１１とする）を得た。得られた重合体１−１１の重量平均分子量Ｍｗ、過酸化水素含有量、ハーゼン、カルシウムイオン捕捉能、および、クレー分散能を測定した。その結果を表１に示す。
（実施例１−１２）
温度計、攪拌機、及び還流冷却器を備えた容量２．５リットルのＳＵＳ製セパラブルフラスコに純水２５８．８ｇを初期仕込し、攪拌下、該純水を沸点還流状態まで昇温した。次いで、攪拌下、還流状態を維持しながら、８０％ＡＡ ４５０．０ｇを重合開始から２４０分間に渡って、３５％Ｈ_２Ｏ_２ ５８．９ｇを重合開始１５分後から１６５分間に渡って、１５％ＮａＰＳ １０２．８ｇを重合開始から２５０分間に渡って、４８％ＮａＯＨ ３７５．０ｇを重合開始から２４０分に渡って、それぞれ別々の滴下ノズルから連続的に均一速度で滴下して重合を完了した。
【０１３２】
重合終了後、沸点還流状態を３０分間維持したまま４８％ＮａＯＨ ２５．０ｇを攪拌下、反応溶液に徐々に滴下して中和した。さらに沸点還流状態を９０分間維持し、固形分濃度３９．６％、最終中和度９６％のポリアクリル酸ナトリウム１−１２（以下、重合体１−１２とする）を得た。得られた重合体１−１２の重量平均分子量Ｍｗ、過酸化水素含有量、ハーゼン、カルシウムイオン捕捉能、および、クレー分散能を測定した。その結果を表１に示す。
（実施例１−１３）
温度計、攪拌機、及び還流冷却器を備えた容量２．５リットルのＳＵＳ製セパラブルフラスコに純水１３８４．８ｇを初期仕込し、攪拌下、該純水を沸点還流状態まで昇温した。次いで、攪拌下、還流状態を維持しながら、８０％ＡＡ ４５０．０ｇを重合開始５分後から２３５分間に渡って、３５％Ｈ_２Ｏ_２ ６１．１ｇを重合開始から１８０分間に渡って、１５％ＮａＰＳ １０６．７ｇを重合開始から２５０分間に渡って、４８％ＮａＯＨ ３７５．０ｇを重合開始５分後から２３５分に渡って、それぞれ別々の滴下ノズルから連続的に均一速度で滴下して重合を完了した。
【０１３３】
重合終了後、沸点還流状態を３０分間維持したまま４８％ＮａＯＨ ２５．０ｇを攪拌下、反応溶液に徐々に滴下して中和した。さらに沸点還流状態を９０分間維持し、固形分濃度２０．６％、最終中和度９６％のポリアクリル酸ナトリウム１−１３（以下、重合体１−１３とする）を得た。得られた重合体１−１３の重量平均分子量Ｍｗ、過酸化水素含有量、ハーゼン、カルシウムイオン捕捉能、および、クレー分散能を測定した。その結果を表１に示す。
（実施例１−１４）
温度計、攪拌機、及び還流冷却器を備えた容量２．５リットルのＳＵＳ製セパラブルフラスコに純水１７９．１ｇを初期仕込し、攪拌下、該純水を沸点還流状態まで昇温した。次いで、攪拌下、還流状態を維持しながら、８０％ＡＡ ４１８．５ｇを重合開始５分後から１７５分間に渡って、３７％ＳＡ ８９．２ｇを重合開始５分後から１７５分間に渡って、３５％Ｈ_２Ｏ_２ ６８．６ｇを重合開始から１２０分に渡って、１５％ＮａＰＳ １３３．３ｇを重合開始から１９０分に渡って、４８％ＮａＯＨ ２６２．４ｇを重合開始５分後から１７５分に渡って、それぞれ別々の滴下ノズルから連続的に均一速度で滴下して重合を完了した。
【０１３４】
重合終了後、沸点還流状態を３０分間維持したまま４８％ＮａＯＨ １０４．２ｇを攪拌下、反応溶液に徐々に滴下して中和した。さらに沸点還流状態を６０分間維持し、固形分濃度４０．１％、最終中和度９５％のポリアクリル酸ナトリウム１−１４（以下、重合体１−１４とする）を得た。得られた重合体１−１４の重量平均分子量Ｍｗ、過酸化水素含有量、ハーゼン、カルシウムイオン捕捉能、および、クレー分散能を測定した。その結果を表１に示す。
（実施例１−１５）
温度計、攪拌機、及び還流冷却器を備えた容量２．５リットルのＳＵＳ製セパラブルフラスコに純水２３１．８ｇを初期仕込し、攪拌下、該純水を沸点還流状態まで昇温した。次いで、攪拌下、該純水の温度を９８℃に維持したまま、８０％ＡＡ ４５０．０ｇを重合開始５分後から１７５分間に渡って、３５％Ｈ_２Ｏ_２８５．７ｇを重合開始から１２０分に渡って、１５％ＮａＰＳ ６６．７ｇを重合開始から１９０分に渡って、４８％ＮａＯＨ ３７５．０ｇを重合開始５分後から１７５分に渡って、それぞれ別々の滴下ノズルから連続的に均一速度で滴下して重合を完了した。
【０１３５】
重合終了後、反応溶液の温度を９８℃に３０分間維持したまま４８％ＮａＯＨ２０．８ｇを攪拌下、反応溶液に徐々に滴下して中和した。さらに沸点還流状態まで昇温して６０分間維持し、固形分濃度４０．３％、最終中和度９５％のポリアクリル酸ナトリウム１−１５（以下、重合体１−１５とする）を得た。得られた重合体１−１５の重量平均分子量Ｍｗ、過酸化水素含有量、ハーゼン、カルシウムイオン捕捉能、および、クレー分散能を測定した。その結果を表１に示す。
【０１３６】
なお、上記各実施例における反応条件をまとめて表２に示した。
【０１３７】
【表１】

【０１３８】
【表２】

【０１３９】
表１の結果から明らかなように、本発明にかかる重合体１−１〜１−１５は、全て重量平均分子量が２００００以下であり、高濃度の条件下であっても一段重合により低分子量かつ、分散度および高硬度水下におけるクレー分散能も良好な重合体が得られることがわかった。また、各重合体水溶液のハーゼンは３００以下であり、非常に色調のよい重合体を得られることがわかった。
【０１４０】
以下では、実施例１−１〜１−１５で得られた本発明の重合体について洗剤組成物としての用途の評価を行うため、次に示す通りの方法により再汚染防止能について測定を行った。その結果を表３にまとめた。
【０１４１】
＜再汚染防止能＞
▲１▼ 洗濯科学協会より入手したＪＩＳ−Ｌ０８０３綿布を５ｃｍ×５ｃｍに切断し、白布を作成した。この白布を予め日本電色工業社製の測色色差計ＮＤ−１００１ＤＰ型を用いて、白色度を反射率にて測定した。
【０１４２】
▲２▼ 塩化カルシウム２水和物０．２９４ｇに純水を加えて５０００ｇとし、硬水を調製した。硬水とすすぎ用の水道水を２５℃の恒温槽につけておいた。
【０１４３】
▲３▼ ターゴットメーターを２５℃にセットし、硬水１Ｌとクレー１ｇをポットに入れ、１００ｒｐｍで１分間攪拌した。その後、白布１０枚を入れ１００ｒｐｍで１分間攪拌した。
【０１４４】
▲４▼ ５％炭酸ナトリウム水溶液４ｇ、５％直鎖アルキルベンゼンスルホン酸ナトリウム塩（以下ＬＡＳと略す）水溶液４ｇ、ゼオライト０．１５ｇ、固形分換算で１％の重合体水溶液５ｇをポットに入れ、１００ｒｐｍで１０分間攪拌した。
【０１４５】
▲５▼ 手で白布の水を切り、２５℃にした水道水１Ｌをポットに入れ、１００ｒｐｍで２分間攪拌した。これを２回行った。
【０１４６】
▲６▼ ▲３▼から▲５▼を３回繰り返した。
【０１４７】
▲７▼ 白布に当て布をして、アイロンでしわを伸ばしながら乾燥させた後、上記測色色差計にて再度白布の白度を反射率にて測定した。
【０１４８】
▲８▼ 以上の測定結果から下式（式２）により再汚染防止率を求めた。
【０１４９】
【数２】

【０１５０】
【表３】

【０１５１】
表３から明らかなように、本発明の製造方法で得られる重合体は、優れた再汚染防止能を有している。
【０１５２】
以下では、実施例１−１〜１−１５で得られた本発明の重合体について洗剤組成物としての用途の評価をさらに行うため、次に示す通りの方法により洗浄能について測定を行った。その結果を表４にまとめた。
【０１５３】
＜洗浄能＞
▲１▼ 洗濯科学協会より入手したＪＩＳ−Ｌ０８０３綿布を５ｃｍ×５ｃｍに切断し、白布を作成した。また湿式人工汚染布も洗濯科学協会より入手した。白布および汚染布を予め日本電色工業社製の測色色差計ＮＤ−１００１ＤＰ型を用いて、白色度を反射率にて測定した。
【０１５４】
▲２▼ 塩化カルシウム２水和物０．２９４ｇに純水を加えて５０００ｇとし、硬水を調製した。硬水とすすぎ用の水道水を２５℃の恒温槽につけておいた。
【０１５５】
▲３▼ ターゴットメーターを２５℃にセットし、硬水５００ｍｌと汚染布５枚、白布５枚をポットに入れ、１００ｒｐｍで１分間攪拌した。
【０１５６】
▲４▼ ５％炭酸ナトリウム水溶液２ｇ、５％ＬＡＳ水溶液２ｇ、ゼオライト０．０７５ｇ、固形分換算で１％の重合体水溶液１０ｇをポットに入れ、１００ｒｐｍで１０分間攪拌した。
【０１５７】
▲５▼ 手で白布と汚染布の水を切り、２５℃にした水道水５００ｍｌをポットに入れ、１００ｒｐｍで２分間攪拌した。これを２回行った。
【０１５８】
▲６▼ 白布と汚染布に当て布をして、アイロンでしわを伸ばしながら乾燥させた後、上記測色色差計にて再度白布と汚染布の白度を反射率にて測定した。
【０１５９】
▲７▼ 以上の測定結果から下式（式３）により洗浄率を求めた。
【０１６０】
【数３】

【０１６１】
【表４】

【０１６２】
表４から明らかなように、本発明の製造方法で得られる重合体は、優れた洗浄能を有している。
【０１６３】
表３と表４の結果を合わせることにより、本発明の洗剤組成物が非常に優れていることが明らかとなった。
【０１６４】
以下では、実施例１−１〜１−１５で得られた本発明の重合体について、水処理剤としての用途の評価を行うため、次に示す通りの方法により炭酸カルシウムスケール防止能について測定を行った。その結果を表５にまとめた。
【０１６５】
＜炭酸カルシウムスケール防止能＞
▲１▼ まず、塩化カルシウム２水和物の１．５６％水溶液および３．０％の炭酸水素ナトリウム水溶液、固形分換算で０．２％の重合体の水溶液を調製した。
【０１６６】
▲２▼ 次に、容量２２５ｍｌのガラス瓶に純水を１７０ｇ入れ、１．５６％塩化カルシウム２水和物水溶液を１０ｇ、固形分換算で０．２％重合体の水溶液３ｇを混合し、さらに炭酸水素ナトリウム水溶液１０ｇおよび塩化ナトリウム７ｇを加えて、全量を２００ｇとした。
【０１６７】
▲３▼ 得られた炭酸カルシウム５３０ｐｐｍの過飽和水溶液を密栓して７０℃で加熱処理を行った。
【０１６８】
▲４▼ 冷却した後、沈殿物を０．１μｍのメンブランフィルターで濾過し、濾液をＪＩＳのＫ０１０１に従い、分析を行った。
【０１６９】
▲５▼ 以上の測定結果から下式（式４）により炭酸カルシウムスケール抑制率（％）を求めた。
【０１７０】
【数４】

【０１７１】
【表５】

【０１７２】
表５から明らかなように、本発明の製造方法で得られる重合体は、非常に優れたスケール防止能を有している。そのため、水処理剤としても有効に利用できることがわかった。
【０１７３】
以下では、実施例１−１〜１−１５で得られた本発明の重合体について、顔料分散剤としての用途の評価を行うため、次に示す通りの方法によりＢ型粘度計を用いて無機顔料分散液の粘度の測定を行った。その結果を表６にまとめた。
【０１７４】
＜分散液の調製とその粘度の測定＞
▲１▼ まず、１０ｗｔ％重合体水溶液を調製した。
【０１７５】
▲２▼ 次に、６００ｍｌポリ容器に純水１５０ｇを入れ、特殊機化工業製のＴＫホモミクサー（撹拌部はラボディスパーＭＲ−Ｌ型を使用）を用い１０００ｒｐｍで攪拌しながら、軽質炭酸カルシウム７０ｇ、重質炭酸カルシウム１０５ｇ及びアルファコート１７５ｇをこの順に徐々に添加した。添加中、顔料が分散しにくくなれば上記１０ｗｔ％重合体水溶液を適宜加えた。
【０１７６】
▲３▼ すべての顔料を添加後、上記１０ｗｔ％重合体水溶液を総量で１０．５ｇになるよう加え、３０００ｒｐｍでさらに１５分間攪拌した。
【０１７７】
▲４▼ 攪拌後２５℃の恒温槽に３０分入れた。その後、Ｂ型粘度計を用い、３分間ローターを回転させて粘度を測定した。
【０１７８】
【表６】

【０１７９】
表６から明らかなように、本発明の製造方法で得られる重合体は、非常に優れた無機顔料分散能を有している。そのため、顔料分散剤としても有効に利用できることがわかった。
【０１８０】
【発明の効果】
本発明によれば、重合に際し、中和度を９９ｍｏｌ％以下にすることにより、製造設備の腐食を回避し、低分子量重合体を高濃度で効率よく製造することができる。また、過硫酸塩と過酸化水素を併用することにより、添加量を大幅に低減し良好に純度の高い低分子量の重合体を製造することができる。さらに、過酸化水素投入条件を規定することにより重合停止反応を抑制し、低分子量の重合体を得ることができる。
【０１８１】
本発明の方法で得られる低分子量重合体は、洗剤組成物や水処理剤、顔料分散剤などの用途に、好適に用いることができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a novel method for obtaining a low-molecular-weight (meth) acrylic acid (salt) -based polymer at a high concentration, a polymer obtained by the method and its use, that is, a detergent containing the polymer. It relates to a composition and the like.
[0002]
[Prior art]
Conventionally, low molecular weight acrylic acid polymers and the like have been known to be very useful for applications as detergent builders, scale inhibitors, and chelating agents.
[0003]
Production methods for obtaining this low molecular weight acrylic acid polymer at a high concentration include (I) JP-A-62-270605, (II) JP-A-5-86125, (III) JP-A-4-268304, Many production methods are disclosed in (IV) JP-A-6-287208 and (V) JP-A-4-266904.
[0004]
In the method disclosed in the above-mentioned publication (I), (meth) acrylic acid and 10% by weight or less of a copolymerizable ethylenic monomer are mixed with 0.01 to 5% by weight of an inorganic phosphoric acid (salt). In the presence, polymerization is carried out using a solvent containing at least 40% by weight of alcohol.
[0005]
In the method disclosed in the above-mentioned publication (II), 95 mol% or more of acrylic acid or acrylate is prepared by maintaining aqueous solution of acrylic acid or acrylate in a pH range of 6 to 9 and introducing nitrogen into the solution. Water-soluble polymer having At this time, the average molecular weight of the polymer is 300 to 10000, and the degree of dispersion is 1.3 to 2.3.
[0006]
In the method disclosed in the above-mentioned publication (III), a monomer mainly composed of (meth) acrylic acid is polymerized while being added to a heated alkaline aqueous solution together with a peroxide-based polymerization initiator. An example is shown in which an aqueous solution of caustic soda is initially charged, the temperature is raised to 90 ° C., and the remaining raw materials are added dropwise to carry out polymerization. By using this method, a low molecular weight polymer having a number average molecular weight of 200 to 2600 can be obtained.
[0007]
In the above-mentioned publication (IV), as a method for producing a polyacrylic acid-based polymer, a method in which acrylic acid is polymerized in an aqueous solution using hypophosphorous acid or a salt thereof as a chain transfer agent is disclosed. By using this method, a polymer having a weight average molecular weight of 20,000 or less and a narrow dispersity can be obtained.
[0008]
In the method disclosed in the above-mentioned publication (V), a monomer mainly composed of (meth) acrylic acid is polymerized while neutralizing with an alkali in an aqueous solution, and the polymerization medium is heated by heat generated in the reaction system. Certain water is distilled off outside the reaction system to obtain a low molecular weight (meth) acrylate polymer.
[0009]
[Problems to be solved by the invention]
However, even with the above-described methods, it has not yet been possible to efficiently produce a low molecular weight (meth) acrylic acid (salt) polymer at a high concentration.
[0010]
Specifically, in the technique disclosed in the above-mentioned publication (I), it is necessary to distill off the alcohol used as the solvent at the end of the polymerization. , Leading to an increase in manufacturing costs. Since inorganic phosphoric acid (salt) is used as a polymerization catalyst, there is also a problem of eutrophication described later.
[0011]
In the technique disclosed in the above-mentioned publication (II), polymerization is carried out while blowing nitrogen. However, this involves scattering of monomers, initiators, chain transfer agents, etc., and causes various problems in the production operation. Occurs.
[0012]
In the technique disclosed in the above-mentioned publication (III), polymerization is carried out under strongly alkaline conditions. In such a neutralized polymerization, when the solid content of the reaction system is increased, the viscosity of the reaction solution in the aqueous solution increases remarkably as the polymerization proceeds, and the molecular weight of the obtained polymer is significantly increased. Tend to increase. In addition, it is reported that corrosion does not occur in the embodiments, and details of the corrosion prevention measures are unknown, but there is a problem that corrosion must be always prevented.
[0013]
In the technique disclosed in the above-mentioned publication (IV), hypophosphorous acid or a salt thereof is used as a chain transfer agent. However, in recent years, in order to prevent eutrophication of rivers and lakes, it has not been used in detergent builders. There is a problem that it tends to phosphatize and goes against this tendency.
[0014]
In the technique disclosed in the above-mentioned publication (V), the polymerization is carried out while evaporating and distilling off the water of the polymerization medium, and the polymerization solid content changes depending on the amount of distilled water. Is difficult. In addition, the number of processes for treating distilled water is increased, and control is performed from the aspect of manufacturing facilities and equipment such as recovery facilities.
[0015]
In addition, there is a method using a sulfite as a chain transfer agent. However, in such a method, impurities such as bowing nitrate are generated, so that the pure content of the polymer is reduced. In addition, equipment for treating sulfurous acid gas generated during polymerization is required, which limits the production facilities and equipment.
[0016]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a low-molecular-weight (meth) acrylic acid (salt) -based polymer having a good color tone on a production facility or an apparatus such as an apparatus for corrosion. Without the need to remove large amounts of alcohol or water, without the need to blow nitrogen, and to provide an efficient manufacturing method that is environmentally friendly. is there. Another object of the present invention is to provide a suitable use of the polymer obtained by the method.
[0017]
[Means for Solving the Problems]
The inventors have conducted intensive studies to solve the above-mentioned conventional problems. As a result, for example, a monomer containing (meth) acrylic acid of 95 mol% or more was neutralized at a degree of neutralization of 99 mol% or less, and hydrogen peroxide was used as an initiator. A low molecular weight (meth) acrylic acid (salt) polymer with good color tone can be obtained by polymerizing together with a persulfate and by carefully controlling the addition conditions of hydrogen peroxide during this polymerization. The present inventors have found that high-concentration production can be performed efficiently, and completed the present invention.
[0018]
That is, the low molecular weight (meth) acrylic acid (salt) polymer according to the present inventionMade ofThe production method includes a monocarboxylic acid (salt) having 3 to 6 carbon atoms, a monoethylenically unsaturated monomer (a) 100 to 95 mol%, and a monoethylenically unsaturated monomer copolymerizable with the monomer (a). A monomer component comprising 0 to 5 mol% of the monomer (b) (the total amount of (a) and (b) is 100 mol%) is prepared by using a polymerization catalyst in the presence of an alkali substance. And a method of polymerizing an aqueous solution at a high concentration, wherein a persulfate and hydrogen peroxide are used in combination as the polymerization catalyst, and the total amount of the alkaline substance neutralizes all the acid groups of the monomer component. So that the dropping of the hydrogen peroxide is terminated at least 10 minutes earlier than the dropping time of the monomer component.And the monomer (a) and the monomer (b) are added to the reaction system by substantially continuously dropping at least 70% by weight based on the total amount used.It is characterized by doing.
[0020]
In the method of the present invention, the dropping of the hydrogen peroxide is completed at least 10 minutes earlier than the dropping time of the monomer component, and the charging of the hydrogen peroxide until the start of the monomer component dropping is performed. The amount may be suppressed so as to be 10% or less of the total input amount, and may be simultaneously performed.
[0021]
The above inventionWhoAccording to the method, by setting the degree of neutralization to 99 mol% or less, corrosion of the production equipment can be avoided and the production can be performed efficiently. Also, by using a combination of a persulfate and hydrogen peroxide, it is possible to significantly reduce the amount of addition and produce a high-purity low-molecular-weight polymer with good purity. Further, by controlling the amount of hydrogen peroxide input conditions as described above, the polymerization termination reaction can be suppressed, and a low-molecular-weight polymer can be obtained at a high concentration.
[0022]
In the above method of the present invention, the final concentration of the polymer is not less than the value obtained by multiplying the weight average molecular weight by 0.002 when the weight average molecular weight is less than 20,000, and 0.08 to the weight average molecular weight when the weight average molecular weight is not less than 20,000. It can be greater than or equal to the square root of the multiplied value. That is, the concentration can be high according to the weight average molecular weight. Also, the final concentration of the polymer can be 30% by weight or more.
[0023]
According to the method of the present invention, a monocarboxylic acid (salt) having 3 to 6 carbon atoms, a monoethylenically unsaturated monomer (a) 100 to 95 mol% and copolymerizable with the monomer (a) Low molecular weight (meta) obtained by polymerizing a monomer component composed of 0 to 5 mol% of monoethylenically unsaturated monomer (b) (the total amount of (a) and (b) is 100 mol%) ) Acrylic acid (salt) based polymers having a weight average molecular weight of 1,000 to 30,000, a dispersity of 1.5 to 5.0, and a hydrogen peroxide concentration of 40% by weight aqueous solution of the polymer being 5 And the Hazen of a 40% by weight aqueous solution of the polymer is 300 or less.The clay dispersibility under high hardness water is 0.47 or more.A low molecular weight (meth) acrylic acid (salt) polymer can be obtained. The polymer is a low molecular weight polymer having good color tone by containing 500 ppm or less of hydrogen peroxide.
[0024]
According to the present invention, a high-performance detergent composition, water treatment agent and pigment dispersant can be obtained by incorporating the polymer obtained by the method of the present invention.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
The method for producing a low molecular weight (meth) acrylic acid (salt) -based polymer and the detergent composition containing the polymer obtained by the method according to the present invention and other uses will be described in detail below. explain.
[0026]
<Low molecular weight (meth) acrylic acid (salt) polymer>
First, the low-molecular-weight (meth) acrylic acid (salt) -based polymer, which is an object in the production method of the present invention, will be described.
[0027]
The low molecular weight (meth) acrylic acid (salt) -based polymer in the present invention refers to a monocarboxylic acid (salt) having 3 to 6 carbon atoms, a monoethylenically unsaturated monomer (a) of 100 to 95 mol%, and the monomer A monomer component comprising a monoethylenically unsaturated monomer (b) 0 to 5 mol% (provided that the total amount of (a) and (b) is 100 mol%) copolymerizable with the compound (a). It is obtained by polymerization.
[0028]
The weight average molecular weight is from 1,000 to 30,000, preferably from 2,000 to 20,000, more preferably from 3,000 to 18,000, particularly preferably from 5,000 to 15,000. If the weight-average molecular weight is less than 1000, the chelating ability is reduced, so that it is not preferable.
[0029]
The low molecular weight (meth) acrylic acid (salt) -based polymer of the present invention preferably has a dispersity of 1.5 to 5.0, preferably 2.0 to 5.0, and more preferably 2.0 to 5.0. -4.0, more preferably 2.5-4.0, and is excellent in the ability to prevent re-contamination when used as a detergent builder. It is preferable that the degree of dispersion is 1.5 or more, because the production of the (meth) acrylic acid (salt) -based polymer does not become complicated, the productivity is good, and the calcium ion trapping ability is increased. A value of 0 or less is preferable because performances such as calcium ion capturing ability, clay dispersing ability, and scale preventing ability are increased.
[0030]
The method for determining the weight average molecular weight and the molecular weight distribution will be described in the examples.
[0031]
In the present invention, the (meth) acrylic acid (salt) -based polymer refers to a (meth) acrylic acid-based polymer in which the carboxyl group is an acid type, a partial salt type, a complete salt type, or a mixture thereof. The partial salt form and the complete salt form are simply described as (salt) hereinafter. Examples of the salt include an alkali metal salt such as sodium and potassium; an alkaline earth metal salt such as calcium and magnesium; an ammonium salt; an organic amine salt such as monoethanolamine and triethanolamine. These salts may be used alone or as a mixture of two or more. When the salt is used, a preferred form is an alkali metal salt such as sodium or potassium, and particularly preferably a sodium salt.
[0032]
<Method for producing low molecular weight (meth) acrylic acid (salt) -based polymer>
Next, a method for producing a low molecular weight (meth) acrylic acid (salt) polymer which is the most important and essential part in the present invention will be described.
[0033]
The method for producing a low molecular weight (meth) acrylic acid (salt) -based polymer according to the present invention is characterized in that the degree of neutralization with respect to an acid is 99 mol% or less by uniform stirring polymerization in an aqueous solvent.
[0034]
Hereinafter, each component in the method for producing a low molecular weight (meth) acrylic acid (salt) -based polymer according to the present invention will be described in further detail.
[0035]
As the monomer (a), specifically, monocarboxylic acid monoethylenically unsaturated monomers such as acrylic acid, methacrylic acid, crotonic acid and α-hydroxyacrylic acid; A salt obtained by partially neutralizing a saturated monomer with an alkali metal such as sodium or potassium, or a salt obtained by completely neutralizing the above monocarboxylic acid monoethylenically unsaturated monomer with ammonia or monoethanolamine or triethanolamine. And partially neutralized salts with organic amines, and (meth) acrylic acid (salt), particularly preferably acrylic acid (salt).
[0036]
The monomer (b) is not particularly limited as long as it is a monoethylenically unsaturated monomer copolymerizable with the monomer (a), and is preferably a water-soluble monomer. For example, maleic acid, fumaric acid, dicarboxylic acid monoethylenically unsaturated monomers such as itaconic acid; salts obtained by partially neutralizing the dicarboxylic acid monoethylenically unsaturated monomer with an alkali metal such as sodium or potassium; Or a salt completely neutralized; a salt obtained by partially neutralizing the above monoethylenically unsaturated dicarboxylic acid monomer with ammonia or an organic amine such as monoethanolamine or triethanolamine, or a salt completely neutralized; vinyl sulfone Monoethylenically unsaturated monomers having a sulfonic acid group, such as acid, allylsulfonic acid, and 3-allyloxy-2-hydroxypropanesulfonic acid; A salt obtained by partially neutralizing a monoethylenically unsaturated monomer having an acid group with an alkali metal such as sodium or potassium, or a salt obtained by completely neutralizing the monoethylenically unsaturated monomer having a sulfonic acid group; Or a salt partially neutralized or completely neutralized with an organic amine such as monoethanolamine or triethanolamine; 3-methyl-2-buten-1-ol (prenol), 3-methyl-3-butene And unsaturated monomers having a hydroxyl group such as -1-ol (isoprenol), 2-hydroxyacrylate and 2-hydroxymethylacrylate; and among the above compounds, monoethylenically unsaturated dicarboxylic acid is more preferable. Monomers, monoethylenically unsaturated monomers containing sulfonic acid groups, and their moieties or Is one or more kinds of compounds selected from all neutralized salt.
[0037]
<Method of adding monomer>
A method for adding a monomer in the method for producing a polymer of the present invention will be described.
[0038]
The monomer (a) and the monomer (b) are reacted by dropping substantially continuously 70% by weight or more, preferably 90% by weight or more, particularly preferably the total amount, of the total amount used, in a substantially continuous manner. Add to system. When the dropping ratio is less than 70% by weight (that is, the initial charge amount is more than 30% by weight), there is a possibility that the monomer (a) or (b) may be polymerized in a block manner at the initial stage of polymerization, and may have a high molecular weight. Therefore, any one of calcium ion trapping ability, clay dispersing ability in high hardness water, and scale preventing ability is adversely affected, which is not preferable. The dropping time of the monomers (a) and (b) is 30 to 360 minutes, preferably 60 to 240 minutes, particularly preferably 90 to 180 minutes. If the dropping time is shorter than 30 minutes, the monomers (a) and (b) are polymerized in a block manner. If the dropping time is longer than 360 minutes, not only is the production facility / equipment restricted, but also the production cost increases. Invite. Any of these is undesirable because it adversely affects the ability to capture calcium ions, the ability to disperse clay in high hardness water, and the ability to prevent scale. The degree of neutralization will be described later.
[0039]
<Polymerization initiator>
In the present invention, as the initiator system used for polymerizing the monomers (a) and (b), one or two or more kinds of persulfates and hydrogen peroxide are used in combination. ing. In some cases, a chain transfer agent or a polyvalent metal ion may be used (here, the polyvalent metal ion acts as a decomposition accelerator for the initiator), or both of them may be used simultaneously. Hereinafter, a specific description will be given.
[0040]
(Radical polymerization initiator)
Specific examples of the persulfate include sodium persulfate, potassium persulfate, and ammonium persulfate. Preferably, it is sodium persulfate.
[0041]
The amount of the hydrogen peroxide to be added is preferably 2.0 to 10.0 g, more preferably 3.0 to 8.0 g, per 1 mol of the monomer. If the amount of hydrogen peroxide is less than 2.0 g, the resulting (meth) acrylic acid (salt) -based polymer tends to have a high polymerization average molecular weight. On the other hand, if the addition amount exceeds 10.0 g, the effect of hydrogen peroxide cannot be obtained as the addition amount increases, and further adverse effects such as an increase in the amount of remaining hydrogen peroxide are caused.
[0042]
The addition amount of the persulfate is preferably 1.0 to 5.0 g, more preferably 2.0 to 4.0 g, per 1 mol of the monomer. If the amount of the persulfate is too small, the molecular weight of the resulting (meth) acrylic acid (salt) polymer tends to increase. On the other hand, if the addition amount is too large, the effect of the persulfate is not obtained as the addition amount is increased, and further, adverse effects such as a decrease in the purity of the obtained (meth) acrylic acid (salt) -based polymer are caused. Become.
[0043]
The weight ratio of the hydrogen peroxide and the persulfate is preferably 0.1 to 5.0 when the weight of the hydrogen peroxide is 1 and the weight of the hydrogen peroxide is 0.1 to 5.0, and the weight ratio is 0.5 to 0.5. It is more preferable that it is 3.0. When the weight ratio of the persulfate is less than 0.1, the weight average molecular weight of the obtained (meth) acrylic acid (salt) polymer tends to increase. On the other hand, if the weight ratio of the persulfate exceeds 5.0, the persulfate is wasted in the polymerization reaction system in a state where the effect of reducing the molecular weight by the addition of the persulfate is not obtained as much as the addition. Will be.
[0044]
In addition, as a method of adding hydrogen peroxide, the amount of substantially continuous dropping is preferably 85% by weight or more of the required predetermined amount, particularly preferably 90% by weight or more based on the total amount used. Most preferably, the whole amount is dropped. Hydrogen peroxide is continuously dropped, but the dropping speed may be changed.
[0045]
It is preferable that 10% or less of the required predetermined amount be dropped by the time when the dropping of the monomer is started under the conditions of the polymerization temperature and the pH at the time of the polymerization described below, more preferably 7 %, More preferably 5% or less, particularly preferably 3% or less. It is further preferable to start dropping at the same time as the monomer dropping start time, and it is more preferable to start dropping while 5 to 60 minutes have passed from the monomer dropping start time, and 10 to 30 minutes have passed. It is particularly preferred to start dropping in between. If hydrogen peroxide exceeding 10% of the required amount is added by the time when the dropping of the monomer is started, the ratio of the concentration of hydrogen peroxide to persulfate increases due to the difference in decomposition rate, and the polymerization may be stopped. is there. On the other hand, if the reaction is started later than 60 minutes from the start time of the dropping of the monomer, a chain transfer reaction due to the addition of hydrogen peroxide does not occur, and the molecular weight increases from the beginning of polymerization.
[0046]
The completion time of the dropping of hydrogen peroxide is determined under the following conditions: polymerization temperature, pH at the time of polymerization.,singleIt may end 10 minutes or more earlier than the end time of the monomer droppingNecessary, End earlier than 30 minutesIs goodGood. In addition, even if the polymerization is completed later than the completion time of the dropping of the monomer, it does not particularly adversely affect the polymerization system. However, since the added hydrogen peroxide is not completely decomposed by the end of the polymerization, the effect as hydrogen peroxide cannot be obtained, and it is wasted. This is not preferred because it may adversely affect the thermal stability of the polymer obtained.
[0047]
The method of adding the persulfate is not particularly limited in view of its decomposability and the like, but the amount of the persulfate dripped substantially continuously is 50% by weight or more of the required amount with respect to the total amount used. It is particularly preferable that the content is 80% by weight or more, and it is most preferable to drop the whole amount. The persulfate is dropped continuously, but the rate of drop may be varied.
[0048]
The dropping time is not particularly limited, but under the conditions of the polymerization temperature and the pH during the polymerization described below, ammonium persulfate, potassium persulfate, persulfates such as sodium persulfate, etc. It is preferable to drop the monomer until the end of the dropping of the monomer, more preferably within 30 minutes after the end of the dropping of the monomer, particularly preferably within 5 to 20 minutes after the dropping of the monomer. preferable. As a result, the effect of significantly reducing the remaining amount of the monomer in the polymer can be found. Note that, even before the completion of the dropping of the monomer, even if the dropping of these initiators is completed, the polymerization is not particularly adversely affected, and may be set according to the remaining amount of the monomer in the obtained polymer. It is good.
[0049]
For these initiators that are relatively quick to decompose, a preferred range is described only for the dropping end time, but the dropping start time is not limited at all and may be set as appropriate. For example, in some cases, the initiator dripping may be started before the monomer dripping is started, or, particularly, in the case of a combined system, one initiator is started to be dripped and a certain time elapses. After that, or after the termination, the dripping of another initiator may be started. Any of them may be appropriately set according to the decomposition rate of the initiator and the reactivity of the monomer.
[0050]
The concentration of the radical polymerization initiator at the time of addition is not particularly limited, but is preferably 5 to 60% by weight, and particularly preferably 10 to 50% by weight. When the concentration of the initiator is less than 5% by weight, the monomer concentration during the polymerization becomes extremely low as a result. Becomes very large. In addition, the efficiency and productivity of transportation and the like are lowered, which is not preferable from the economical viewpoint. On the other hand, when the content exceeds 60% by weight, there is a problem in terms of safety and easy dropping.
[0051]
Further, in addition to the above-mentioned persulfate and hydrogen peroxide, another radical polymerization initiator may be used in combination. Other radical polymerization initiators include, for example, 2,2′-azobis (2-amidinopropane) dihydrochloride, 4,4′-azobis-4-cyanovaleric acid, azobisisobutyronitrile, 2,2 ′ Azo compounds such as -azobis (4-methoxy-2,4-dimethylvaleronitrile), organic peroxides such as benzoyl peroxide, lauroyl peroxide, peracetic acid, di-t-butyl peroxide, cumene hydroperoxide, etc. Is raised.
[0052]
(Chain transfer agent)
If necessary, a chain transfer agent may be used in combination with a radical polymerization initiator as a polymer molecular weight modifier within a range that does not adversely affect the polymerization. Examples of the chain transfer agent include sulfites, bisulfites, hypophosphites, mercaptopropionic acid, thioglycolic acid, and the like, but are not particularly limited, and these may be used alone or two kinds. A combination of the above may be used.
[0053]
The amount used is preferably within twice the amount of the initiator by weight. Even if it is used more than twice, the effect of addition is no longer exhibited, and the pure content of the polymer is undesirably reduced. The method of adding the chain transfer agent and the time of the dropping are not particularly limited as long as the solution is dropped, and may be appropriately set according to the case.
[0054]
(Polyvalent metal ion)
Further, if necessary, a polyvalent metal ion may be used in combination as a decomposition accelerator of the radical polymerization initiator. Effective polyvalent metal ions that can be used include Fe²⁺, Fe³⁺, Cu²⁺, Cu⁺, V²⁺, V³⁺, VO²⁺Etc., but preferably Fe²⁺, Fe³⁺It is. These may be used alone or in combination of two or more.
[0055]
The method of adding these polyvalent metal ions is not particularly limited, but it is preferable to add them before the completion of the dropwise addition of the monomer, and it is particularly preferable to initially charge the entire amount. Further, the amount used is preferably 100 ppm or less, more preferably 70 ppm or less, further preferably 50 ppm or less, particularly preferably 30 ppm or less, based on the total amount of the reaction solution. If it exceeds 100 ppm, the effect of the addition will no longer be seen, and the resulting polymer will be too colored and may not be used when used as a detergent composition, which is not preferred.
[0056]
The supply form of the polyvalent metal ion is not particularly limited, and any metal compound or metal may be used as long as it can be ionized in the polymerization reaction system. Examples of such metal compounds and metals include vanadium oxytrichloride, vanadium trichloride, vanadium oxalate, vanadium sulfate, vanadic anhydride, ammonium metavanadate, ammonium hypovanadas [(NH₄)₂SO₄・ VSO₄・ 6H₂O], ammonium sulfate vanadas [(NH₄) V (SO₄)₂・ 12H₂O], copper (II) acetate, copper (II) bromide, copper (II) acetyl acetate, cupric chloride, copper ammonium chloride, copper carbonate, copper (II) chloride, copper (II) citrate, copper formate (II), copper (II) hydroxide, copper nitrate, copper naphthenate, copper (II) oleate, copper maleate, copper phosphate, copper (II) sulfate, cuprous chloride, copper (I) cyanide , Copper iodide, copper (I) oxide, copper thiocyanate, iron acetylacetonate, ferric ammonium citrate, ferric ammonium oxalate, ferrous ammonium sulfate, ferric ammonium sulfate, iron citrate, fumaric acid Water-soluble metal salts such as iron, iron maleate, ferrous lactate, ferric nitrate, iron pentacarbonyl, ferric phosphate, and ferric pyrophosphate, vanadium pentoxide, copper (II) oxide, ferric oxide Metal oxides such as ferrous and ferric oxides, copper sulfide II), mention may be made of metal sulfides such as iron sulfide, copper powder, iron powder or the like. It may be a metal eluted from the device.
[0057]
The monomer composition for polymerization used in the present invention contains the above-mentioned monomers, a polymerization initiator, a chain transfer agent, and additives such as polyvalent metal ions. In addition, besides, as long as the polymerization reaction of the present invention is not inhibited, as long as the physical properties of the resulting water-soluble polymer are not inhibited, other additives other than the exemplified additives may be contained in the monomer composition. I don't care.
[0058]
<Polymerization neutralization degree and its adjustment method>
The degree of neutralization during the polymerization (that is, during dropping of the monomer) is 99 mol% or less, preferably 50 to 95 mol% or less, based on the total amount of the acid amounts of the monomer (a) and the monomer (b). It is. If the degree of neutralization is less than 50 mol%, decomposition of hydrogen peroxide does not sufficiently occur, and the weight average molecular weight tends to increase. On the other hand, if the content exceeds 99 mol%, corrosive conditions of strong alkali may occur, so that the production equipment may be corroded at high temperatures, and furthermore, hydrogen peroxide may be decomposed by the alkali, resulting in an increased amount of addition. There is also. The degree of neutralization after the completion of the polymerization (that is, after the completion of the dropping of the monomer) is determined by the sum of the acid amounts of the monomers (a) and (b) in order to promote the decomposition of the remaining hydrogen peroxide. Is preferably 80 mol% or more, more preferably 90 mol% or more, and still more preferably 95 mol% or more.
[0059]
Examples of the monomer neutralizing agent include hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide; hydroxides of alkaline earth metals such as calcium hydroxide and magnesium hydroxide: ammonia; Organic amines such as triethanolamine are exemplified. These may be used alone or as a mixture of two or more. Preferred are hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide, and particularly preferred is sodium hydroxide. Hereinafter, in the present invention, these are simply described as "neutralizing agents".
[0060]
Neutralization may be performed in advance before supplying the monomer to the reactor, or neutralization may be performed in the reactor by separately supplying the monomer and the neutralizing agent to the reactor. good. Further, the degree of neutralization from the start of polymerization to the end of polymerization need not be constant as long as it is within the above range, and specifically, the degree of neutralization may be lowered in the first half of polymerization, or Alternatively, the degree of neutralization may be increased in the latter half of the polymerization.
[0061]
The concentration of the neutralizing agent at the time of addition is not particularly limited, but is preferably 10 to 70% by weight, particularly preferably 30 to 50% by weight. When the concentration of the neutralizing agent is less than 10% by weight, as a result, the concentration of the monomer during the polymerization becomes very low, so that the polymerizability of the monomer becomes very poor, and the monomer content in the obtained polymer is reduced. The amount of body remaining becomes very large. In addition, the efficiency and productivity of transportation and the like are lowered, which is not preferable from the economical viewpoint. Conversely, if it exceeds 70% by weight, it is not preferable in terms of safety and simple dropping.
[0062]
<Other polymerization conditions>
Other polymerization conditions in the method for producing a polymer of the present invention include temperature, concentration, pressure, and solvent during polymerization. These will be specifically described in order.
[0063]
(Polymerization temperature)
The temperature at the time of polymerization is not particularly limited at the time of the initial preparation, and is from the start of polymerization due to the start of the dropping of the monomer or the polymerization initiator to the end of the polymerization (that is, when the dropping of all the monomer and the polymerization initiator is completed). In some cases, the temperature is preferably 60 ° C. or higher, more preferably 90 ° C. or higher, particularly preferably near the boiling point of the polymerization solvent, and most preferably the boiling point of the polymerization solvent until the aging time is set after the completion of the dropping. When pH and concentration are adjusted after the completion of the polymerization, the adjustment is not particularly limited and may be appropriately performed.
[0064]
If the temperature at the time of the polymerization is lower than 60 ° C., the decomposition efficiency of the polymerization initiator is deteriorated, and the residual amount of the monomer in the obtained polymer may be undesirably increased. Further, it is very preferable to carry out the polymerization at the boiling point, since the temperature control becomes very easy, the reproducibility of the polymerization is good, and the quality of the obtained polymer is very stable. However, when there is large foaming, the temperature is preferably lower than the boiling point.
[0065]
(Polymerization concentration)
The final concentration of the obtained polymer is represented by the following inequality.
[0066]
When Mw is less than 20,000, C ≧ A × Mw
When Mw is 20,000 or more, C ≧ (B × Mw)^1/2
Where C = final concentration of polymer obtained; A = 0.002 and B = 0.08, preferably A = 0.0025 and B = 0.125, more preferably A = 0.003 and B = 0.18; Mw = weight average molecular weight of the obtained polymer.
Alternatively, the final concentration of the obtained polymer is preferably 30% by weight or more, more preferably 33% by weight or more, further preferably 35% by weight or more, even more preferably 37% by weight or more, and particularly preferably 40 to 70% by weight. %, And the concentration of the droplet is adjusted so as to match this. When the final concentration of the polymer is less than the above range, the concentration during the polymerization becomes extremely low as a result, so that the residual amount of the monomer in the obtained polymer becomes extremely poor in the polymerizability of the monomer. Will be very much. In addition, the efficiency and productivity of transportation and the like are lowered, which is not preferable from the economical viewpoint. Conversely, if it exceeds 70% by weight, the concentration during the polymerization becomes extremely high, so that the reaction solution has a very high viscosity, does not form a uniform polymerization, and may have a very high molecular weight. Further, the solution viscosity of the obtained polymer becomes extremely high, which is not preferable from the viewpoint of handling. The final concentration of the polymer after completion of the polymerization may be appropriately adjusted by concentration or dilution.
[0067]
(Polymerization pressure)
The pressure during the polymerization is not particularly limited, and any of pressurization, normal pressure (atmospheric pressure), and reduced pressure may be used.
[0068]
(solvent)
As the solvent in the method for producing a polymer of the present invention, an organic solvent may be appropriately added as necessary, in a range that does not adversely affect the polymerization, in order to improve the solubility of the monomer used in the polymerization in the solvent. , Preferably an aqueous solvent, preferably 80% by weight or more of water, and particularly preferably water alone.
[0069]
Specific examples of the organic solvent include lower alcohols such as methanol, ethanol and isopropyl alcohol, lower ketones such as acetone, methyl ethyl ketone and diethyl ketone, ethers such as dimethyl ether, diethyl ether and dioxane, and dimethyl formaldehyde and the like. Examples thereof include amides and the like. These may be used alone or as a mixture of two or more, but isopropyl alcohol is preferred. Isopropyl alcohol has an effect as a chain transfer agent, and can lower the molecular weight of the polymer. These organic solvents may be removed after completion of the polymerization.
[0070]
The solvent is preferably initially charged at least 10% by weight, more preferably at least 12% by weight, based on the total amount of the monomers, neutralizers, polymerization initiators and other additives and solvents used, It is particularly preferable to initially charge 15% by weight or more. If it is less than 10% by weight, the monomer concentration at the start of the polymerization will be high, and the molecular weight may be increased.
[0071]
<Low molecular weight (meth) acrylic acid (salt) polymer with good color tone>
In the present invention, the low molecular weight (meth) acrylic acid (salt) polymer having a good color tone is defined as a monocarboxylic acid (salt) having 3 to 6 carbon atoms and a monoethylenically unsaturated monomer (a) of 100 to 95 mol%. And a monomer component comprising 0 to 5 mol% of a monoethylenically unsaturated monomer (b) copolymerizable with the monomer (a), which is obtained by polymerization at 40% by weight. The Hazen of the aqueous polymer solution is 300 or less.
[0072]
The weight average molecular weight is from 1,000 to 30,000, preferably from 2,000 to 20,000, more preferably from 3,000 to 18,000, particularly preferably from 5,000 to 15,000. If the weight-average molecular weight is less than 1000, the chelating ability is reduced, so that it is not preferable.
[0073]
The dispersity is from 1.5 to 5.0, preferably from 2.0 to 5.0, more preferably from 2.0 to 4.0, particularly preferably from 2.5 to 4.0, and as a detergent builder. Excellent ability to prevent re-contamination when used. A (meth) acrylic acid (salt) -based polymer having a dispersity of less than 1.5 is not preferable because production becomes complicated, productivity is deteriorated, and the ability to capture calcium ions is lowered. It is not preferable because the performance such as the ion trapping ability, the clay dispersing ability and the scale preventing ability is reduced.
[0074]
The hydrogen peroxide concentration of the aqueous polymer solution at 40% by weight is 5 to 500 ppm, preferably 5 to 300 ppm, more preferably 5 to 200 ppm, and particularly preferably 5 to 100 ppm. If the concentration of hydrogen peroxide is less than 5 ppm, the effect of suppressing the coloring of the polymer cannot be obtained, and therefore, it is not preferable.
[0075]
Hazen is 300 or less, preferably 200 or less, more preferably 100 or less, even more preferably 90 or less, and particularly preferably 80 or less. When the Hazen exceeds 300, the coloring of the composition to which the polymer is added becomes remarkable, which is not preferable.
Clay dispersibility under high hardness water is 0.47 or more, preferably 0.47 to 0.60.
[0076]
The weight average molecular weight,Degree of dispersionDispersibility in water, hydrogen peroxide concentration, Hazen and high hardness waterThe method for determining is described in the section of Examples.
[0077]
<Preferred use of low molecular weight (meth) acrylic acid (salt) -based polymer obtained by the production method of the present invention>
(Detergent composition)
In the detergent composition of the present invention, the compounding amount of the polymer of the present invention is 1 to 20% by weight of the whole detergent composition, and the compounding amount of the surfactant is 5 to 70% by weight of the whole detergent composition. In some cases, the enzyme may be added in a range of 5% by weight or less.
[0078]
If the blending amount of the polymer of the present invention is less than 1% by weight, the effect of addition does not appear, and if it exceeds 20% by weight, the effect of addition does not lead to improvement in detergency and is disadvantageous economically, which is not preferable. On the other hand, if the amount of the surfactant, which is the main component of the detergent composition, is out of the above range, the balance with other components may be lost and the detergency of the detergent composition may be adversely affected. When the enzyme is added, it contributes to the improvement of the detergency. However, if it exceeds 5% by weight, the effect of the addition is no longer exhibited, and it is economically disadvantageous, which is not preferable.
[0079]
As the surfactant, at least one selected from the group consisting of an anionic surfactant, a nonionic surfactant, an amphoteric surfactant and a cationic surfactant can be used. The anionic surfactant is not particularly limited. For example, alkyl benzene sulfonate, alkyl or alkenyl ether sulfate, alkyl or alkenyl sulfate, α-olefin sulfonate, α-sulfo fatty acid or ester salt, alkane sulfone Examples thereof include acid salts, saturated or unsaturated fatty acid salts, alkyl or alkenyl ether carboxylate salts, amino acid surfactants, N-acyl amino acid surfactants, alkyl or alkenyl phosphate esters and salts thereof.
[0080]
The nonionic surfactant is not particularly limited, but includes, for example, polyoxyalkylene alkyl or alkenyl ether, polyoxyethylene alkyl phenyl ether, higher fatty acid alkanolamide or an alkylene oxide adduct thereof, sucrose fatty acid ester, alkyl glycooxide, Fatty acid glycerin monoester, alkylamine oxide and the like can be mentioned.
[0081]
The amphoteric surfactant is not particularly limited, but includes, for example, a carboxy-type or sulfobetaine-type amphoteric surfactant, and the cationic surfactant is not particularly limited. Ammonium salts and the like can be mentioned.
[0082]
As the enzyme to be added to the detergent composition of the present invention, protease, lipase, cellulase and the like can be used. Particularly, protease, alkaline lipase and alkaline cellulase having high activity in an alkaline washing solution are preferable.
[0083]
Further, if necessary, the detergent composition of the present invention may contain a known alkali builder, chelate builder, anti-redeposition agent, soil release agent, color transfer inhibitor, softener, fluorescent agent, bleaching agent, bleaching aid. Ingredients commonly used in detergent compositions such as fragrances and the like may be blended. Further, zeolite may be blended.
[0084]
Silicates, carbonates, sulfates and the like can be used as the alkali builder. As the chelate builder, diglycolic acid, oxycarboxylate, EDTA (ethylenediaminetetraacetic acid), DTPA (diethylenetriaminepentaacetic acid), citric acid, and the like can be used as needed. Alternatively, a known water-soluble polycarboxylic acid-based polymer may be used as long as the effects of the present invention are not impaired.
[0085]
(Water treatment agent)
The water treatment agent is preferably composed of only the polymer of the present invention, and if necessary, as another compounding agent, a composition containing a polymerized phosphate, a phosphonate, an anticorrosive, a slime control agent, and a chelating agent. It can also be a thing. In any case, it is useful for scale prevention in a cooling water circulation system, a boiler water circulation system, a seawater desalination apparatus, a pulp digester, a black liquor concentrator, and the like. Further, a known water-soluble polymer may be contained within a range not affecting the performance and the effect.
[0086]
(Pigment dispersant)
The pigment dispersant preferably comprises only the polymer of the present invention, and if necessary, other compounding agents such as polymerized phosphoric acid and salts thereof, phosphonic acid and salts thereof, and polyvinyl alcohol may be used.
[0087]
In any case, this dispersant exhibits good performance as a dispersant for inorganic pigments such as heavy or light calcium carbonate and clay used for paper coating. For example, by adding a small amount of the pigment dispersant of the present invention to an inorganic pigment and dispersing it in water, it has a low viscosity and high fluidity, and has good aging stability of its performance, Highly concentrated inorganic pigment slurries such as calcium carbonate slurries can be produced.
[0088]
The amount of the pigment dispersant used is preferably 0.05 to 2.0 parts by weight based on 100 parts by weight of the pigment. If the amount is less than 0.05 part, a sufficient dispersing effect cannot be obtained. Conversely, if the amount exceeds 2.0 parts by weight, the effect corresponding to the added amount can no longer be obtained, which may be economically disadvantageous. It is not preferable because there is.
[0089]
(Fiber treatment agent)
As the fiber treatment agent, the polymer of the present invention may be used alone, but may also be used as a composition containing additives such as a dye, a peroxide, and a surfactant. Examples of the additives include those usually used in fiber treatment agents. Although the ratio of the polymer of the present invention and the additive is not particularly limited, the additive is preferably 0.1 to 100 parts by weight, more preferably 0.1 to 100 parts by weight, based on 1 part by weight of the polymer of the present invention. Is blended in a ratio of 0.2 to 80 parts by weight, more preferably 1 to 50 parts by weight. If the amount of the additive is less than 0.1 part by weight, the effect of addition tends to be insufficient, and if it exceeds 100 parts by weight, the effect of the polymer of the present invention tends not to be exhibited. In addition, the fiber treating agent containing the polymer of the present invention may further contain a polymer other than the polymer of the present invention as long as the performance and the effect are not impaired. The content of the polymer of the present invention in the fiber treatment agent is not particularly limited, but is preferably 1 to 100% by weight, more preferably 5 to 100% by weight, based on the whole fiber treatment agent.
[0090]
The fibers which can be used for the fiber treating agent containing the polymer of the present invention are not particularly limited. For example, cellulosic fibers such as cotton and hemp; chemical fibers such as nylon and polyester; animal fibers such as wool and silk; Semi-synthetic fibers such as silk, and woven and blended products thereof.
[0091]
When the fiber treating agent containing the polymer of the present invention is used in the refining step, it is preferable to blend the polymer of the present invention with an alkali agent and a surfactant. When applied to the bleaching step, it is preferable to blend the polymer of the present invention, a peroxide and a silicic acid-based agent such as sodium silicate as a decomposition inhibitor of an alkaline bleaching agent.
[0092]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In the following, “%” indicates “% by weight”. The measuring methods of the physical properties are as follows.
[0093]
<Physical property measurement method>
(Method of measuring weight average molecular weight (Mw))
(1) It was measured by GPC (gel permeation chromatography). The column used for the measurement was GF-7MHQ (manufactured by Showa Denko), and the mobile phases were 34.5 g of disodium hydrogen phosphate dodecahydrate and 46.2 g of sodium dihydrogen phosphate dihydrate (both were reagents). Pure water was added to a special grade (reagents used in the following measurements were all used) to make the total amount 5000 g, and then an aqueous solution filtered through a 0.45 micron membrane filter was used.
[0094]
{Circle around (2)} The pump used was L-7110 (manufactured by Hitachi), the flow rate of the mobile phase was set to 0.5 ml / min, and the detector was UV with a wavelength of 214 nm (model 481 manufactured by Nippon Waters). At that time, the column temperature was kept constant at 35 ° C.
[0095]
{Circle around (3)} As a calibration curve, a sodium polyacrylate standard sample (manufactured by Soka Kagaku) was used.
[0096]
{Circle around (4)} The sample was diluted with the solvent of the mobile phase to prepare a 0.1% by weight sample solution. From the calibration curve and the sample solution, the weight average molecular weight of the polymer was measured.
[0097]
(Method of measuring solid content concentration)
{Circle around (1)} About 1 g of a sample was placed in an aluminum cup precisely weighed to 0.1 mg and precisely weighed.
[0098]
{Circle around (2)} The aluminum cup was placed in a dryer set at 110 ° C. and dried for 2 hours.
[0099]
{Circle around (3)} After drying, the aluminum cup was transferred to a desiccator, allowed to cool to room temperature for 10 minutes, and then precisely weighed.
[0100]
{Circle around (4)} The value obtained by dividing the weight of the sample after drying by the weight of the sample before drying and multiplying by 100 was defined as the solid content concentration.
[0101]
(Method of measuring hydrogen peroxide content)
{Circle around (1)} 2.0 g of potassium iodide was placed in a 200 ml Mayer flask, 100 ml of pure water was added, the mixture was stirred with a magnetic stirrer, and after dissolution, covered with light-shielding paper.
[0102]
(2) 30 ml of 9 mol / l sulfuric acid was added with a whole pipette.
[0103]
(3) Next, 5 g of the test sample (polymer) was added to the flask of (2) and stirred for 2 minutes.
[0104]
{Circle around (4)} A 0.01 mol / l aqueous solution of sodium thiosulfate was added dropwise until the yellow color became pale. Further, 1 ml of a 1% starch solution was added, and titration was performed until the iodine starch color disappeared.
[0105]
{Circle around (5)} From the above measurement results, the hydrogen peroxide content was determined by the following equation (Equation 1).
[0106]
(Equation 1)

[0107]
(Measurement method of Hazen)
{Circle around (1)} The Hazen of the aqueous polymer solution was measured using a spectroscopic color difference meter SE-2000 (manufactured by Nippon Denshoku Industries).
[0108]
(Calcium ion trapping ability)
{Circle around (1)} First, 50 g of an aqueous solution of 0.01 mol / l, 0.001 mol / l, and 0.0001 mol / l were prepared using calcium chloride dihydrate as a calcium ion standard solution for a calibration curve. The pH was adjusted to a range of 9 to 11 with an aqueous 0.8% NaOH solution, and 1 ml of a 4 mol / l aqueous potassium chloride solution (hereinafter abbreviated as 4M-KCl aqueous solution) was added. Then, the mixture was sufficiently stirred using a magnetic stirrer. Thus, a sample solution for a calibration curve was prepared. A required amount of a 0.0012 mol / l aqueous solution (using 50 g per sample) was also prepared using calcium chloride dihydrate as a test calcium ion standard solution.
[0109]
{Circle around (2)} Then, 10 mg of the test sample (polymer) was weighed in terms of solid content in a 100 cc beaker, and 50 g of the test calcium ion standard solution prepared in <1> was added, and the mixture was sufficiently stirred using a magnetic stirrer. . Further, similarly to the sample solution for the calibration curve, the pH was adjusted to a range of 9 to 11 with a 4.8% NaOH aqueous solution, and 1 ml of a 4M-KCl aqueous solution was added to prepare a test sample solution.
[0110]
{Circle around (3)} The calibration curve sample solution and the test sample solution thus prepared were measured with an Orion calcium ion electrode 93-20 using an Orion ion analyzer EA920.
[0111]
{Circle around (4)} The amount of calcium ions captured by the sample (polymer) is calculated from the calibration curve and the measured value of the sample liquid for the test, and the captured amount per gram of the polymer solid content is expressed in terms of g of calcium carbonate. This value was used as the calcium ion trapping ability value.
[0112]
(Clay dispersing ability under high hardness water)
{Circle around (1)} First, a glycine buffer solution was prepared by adding 67.56 g of glycine, 52.6 g of sodium chloride and 60 ml of a 1 mol / l NaOH aqueous solution to 600 g by adding ion-exchanged water.
[0113]
(2) A dispersion was prepared by taking 0.3268 g of calcium chloride dihydrate and 60 g of the prepared solution of (1), and adding pure water to make 1000 g. Further, a 0.1% polymer aqueous solution in terms of solid content was prepared.
[0114]
{Circle around (3)} In a general test tube used for an experiment of about 30 cc, put 0.3 g of clay of JIS test powder I, 8 kinds (Kanto Rohm, fine particles: Japan Powder Industry Technology Association), and 27 g of the dispersion and 3 g of the aqueous polymer solution were added. At this time, the calcium concentration of the test solution was 200 ppm in terms of calcium carbonate.
[0115]
{Circle around (4)} After the test tube was sealed with parafilm, the clay was gently shaken so as to be dispersed throughout, and further shaken up and down 20 times. After the test tube was allowed to stand for 20 hours in a place out of direct sunlight, 5 ml of the supernatant of the dispersion was collected with a whole pipette.
[0116]
{Circle around (5)} The absorbance (ABS) of this solution was measured using a UV spectrometer at a wavelength of 380 nm in a 1 cm cell, and this value was taken as the clay dispersing ability value under high hardness water.
[0117]
Next, specific examples of the present invention will be described.
[0118]
(Example 1-1)
Initially, 193.0 g of ion-exchanged water (hereinafter referred to as pure water) was charged into a 2.5-liter SUS separable flask equipped with a thermometer, a stirrer, and a reflux condenser, and the pure water was heated to a boiling point under stirring. The temperature was raised to the reflux state. Then, while maintaining the reflux state under stirring, 450.0 g of an 80% aqueous solution of acrylic acid (hereinafter referred to as 80% AA) was added to 114.3 g of a 35% aqueous solution of hydrogen peroxide (hereinafter referred to as 35%) over 180 minutes from the start of polymerization. % H₂O₂133.3 g of a 15% aqueous sodium persulfate solution (hereinafter abbreviated as 15% NaPS) over a period of 60 minutes from the start of the polymerization, and a 48% aqueous sodium hydroxide solution (hereinafter a 48% 333.3 g of NaOH) was continuously dropped at a uniform rate from separate dropping nozzles over a period of 180 minutes from the start of the polymerization. Further, the boiling point reflux state was maintained for 20 minutes after the completion of all the dropwise additions to complete the polymerization.
[0119]
After the completion of the polymerization, while maintaining the boiling point reflux state for 30 minutes, 62.5 g of 48% NaOH was gradually added dropwise to the reaction solution with stirring to neutralize. Thus, sodium polyacrylate 1-1 (hereinafter, referred to as polymer 1-1) having a solid content of 39.5% and a final degree of neutralization of 95% was obtained. The weight average molecular weight Mw, hydrogen peroxide content, Hazen, calcium ion trapping ability, and clay dispersing ability of the obtained polymer 1-1 were measured. Table 1 shows the results.
[0120]
(Example 1-2)
35% H in Example 1-1₂O₂Polymerization was carried out in the same manner except that the amount added was 57.1 g. Then, while maintaining the boiling point reflux state for 30 minutes, 62.5 g of 48% NaOH was gradually added dropwise to the reaction solution with stirring to neutralize. Thus, sodium polyacrylate 1-2 (hereinafter, referred to as polymer 1-2) having a solid content of 41.5% and a final degree of neutralization of 95% was obtained. The weight average molecular weight Mw, hydrogen peroxide content, Hazen, calcium ion trapping ability, and clay dispersing ability of the obtained polymer 1-2 were measured. Table 1 shows the results.
[0121]
(Example 1-3)
35% H in Example 1-2₂O₂Was polymerized in the same manner except that was continuously dropped at a uniform rate over 90 minutes from the start of polymerization. Then, while maintaining the boiling point reflux state for 30 minutes, 62.5 g of 48% NaOH was gradually added dropwise to the reaction solution with stirring to neutralize. Thus, sodium polyacrylate 1-3 (hereinafter, referred to as polymer 1-3) having a solids concentration of 41.7% and a final degree of neutralization of 95% was obtained. The weight average molecular weight Mw, hydrogen peroxide content, Hazen, calcium ion scavenging ability, and clay dispersing ability of the obtained polymer 1-3 were measured. Table 1 shows the results.
[0122]
(Example 1-4)
35% H in Example 1-1₂O₂The polymerization was carried out in the same manner except that the amount of dropwise addition was 85.7 g and the dropwise addition was continued at a uniform rate over 150 minutes from the start of polymerization. Then, while maintaining the boiling point reflux state for 30 minutes, 62.5 g of 48% NaOH was gradually added dropwise to the reaction solution with stirring to neutralize. Thus, sodium polyacrylate 1-4 (hereinafter, referred to as polymer 1-4) having a solid content of 40.5% and a final degree of neutralization of 95% was obtained. The weight average molecular weight Mw, hydrogen peroxide content, Hazen, calcium ion trapping ability and clay dispersing ability of the obtained polymer 1-4 were measured. Table 1 shows the results.
[0123]
(Example 1-5)
35% H in Example 1-4₂O₂Polymerization was carried out in the same manner except that the amount of the dropwise addition was 68.6 g. Then, while maintaining the boiling point reflux state for 30 minutes, 62.5 g of 48% NaOH was gradually added dropwise to the reaction solution with stirring to neutralize. Thus, sodium polyacrylate 1-5 (hereinafter, referred to as polymer 1-5) having a solid content of 41.0% and a final degree of neutralization of 95% was obtained. The weight average molecular weight Mw, hydrogen peroxide content, Hazen, calcium ion trapping ability, and clay dispersing ability of the obtained polymer 1-5 were measured. Table 1 shows the results.
[0124]
(Example 1-6)
Polymerization was carried out in the same manner as in Example 1-5 except that the amount of the 48% NaOH dropped was 375.0 g. Thereafter, while maintaining the boiling point reflux state for 30 minutes, 20.8 g of 48% NaOH was gradually dropped into the reaction solution with stirring to neutralize. Thus, sodium polyacrylate 1-6 (hereinafter, referred to as polymer 1-6) having a solid content of 41.3% and a final degree of neutralization of 95% was obtained. The weight average molecular weight Mw, hydrogen peroxide content, Hazen, calcium ion trapping ability, and clay dispersing ability of the obtained polymer 1-6 were measured. Table 1 shows the results.
[0125]
(Example 1-7)
35% H in Example 1-6₂O₂Polymerization was carried out in the same manner except that the amount of the dropwise addition was 114.3 g. Then, while maintaining the boiling point reflux state for 30 minutes, 20.8 g of 48% NaOH was gradually added dropwise to the reaction solution with stirring to neutralize. Thus, sodium polyacrylate 1-7 (hereinafter, referred to as polymer 1-7) having a solid content of 39.9% and a final degree of neutralization of 95% was obtained. The weight average molecular weight Mw, hydrogen peroxide content, Hazen, calcium ion trapping ability, and clay dispersing ability of the obtained polymer 1-7 were measured. Table 1 shows the results.
[0126]
(Example 1-8)
Polymerization was carried out in the same manner as in Example 1-4 except that the amount of the 15% NaPS dropped was 83.3 g and the amount of the 48% NaOH dropped was 375.0 g. Then, while maintaining the boiling point reflux state for 30 minutes, 20.8 g of 48% NaOH was gradually added dropwise to the reaction solution with stirring to neutralize. Thus, sodium polyacrylate 1-8 (hereinafter referred to as polymer 1-8) having a solid content of 42.1% and a final degree of neutralization of 95% was obtained. The weight average molecular weight Mw, hydrogen peroxide content, Hazen, calcium ion trapping ability, and clay dispersing ability of the obtained polymer 1-8 were measured. Table 1 shows the results.
[0127]
(Example 1-9)
195.9 g of pure water was initially charged into a 2.5-liter SUS separable flask equipped with a thermometer, a stirrer, and a reflux condenser, and the temperature of the pure water was raised to a boiling point reflux state with stirring. Then, while stirring and maintaining the reflux state, 263.8 g of 80% AA was polymerized with 533.8 g of a 37% aqueous solution of sodium acrylate (hereinafter referred to as 37% SA) from 5 minutes after the initiation of polymerization to 175 minutes. 35% H for 30 minutes from the start 30 minutes₂O₂  54.9 g of 150% of 15% NaPS over 190 minutes from the start of polymerization, 200.0 g of 48% NaOH over 180 minutes from the start of polymerization, and 200.0 g of 48% NaOH over 180 minutes from the start of polymerization. The polymerization was completed by dropping continuously at a uniform speed from the dropping nozzle.
[0128]
After the completion of the polymerization, while maintaining the boiling point reflux state for 30 minutes, 20.8 g of 48% NaOH was gradually dropped into the reaction solution with stirring to neutralize. Further, the reaction solution was concentrated while maintaining the boiling point reflux state for 60 minutes to obtain sodium polyacrylate 1-9 (hereinafter referred to as polymer 1-9) having a solid content of 40.0% and a final degree of neutralization of 95%. Obtained. The weight average molecular weight Mw, hydrogen peroxide content, Hazen, calcium ion trapping ability, and clay dispersing ability of the obtained polymer 1-9 were measured. Table 1 shows the results.
[0129]
(Example 1-10)
231.3 g of pure water was initially charged into a 2.5-liter SUS separable flask equipped with a thermometer, a stirrer, and a reflux condenser, and the temperature of the pure water was raised to a boiling point reflux state with stirring. Next, while maintaining the reflux state under stirring, 450.0 g of 80% AA was added to 35% H from 5 minutes after the initiation of polymerization to 235 minutes.₂O₂  61.1 g were separately separated from each other for 106.7 g of 15% NaPS over 250 minutes from the start of polymerization, and 375.0 g of 48% NaOH over 235 minutes from 5 minutes after the start of polymerization. The polymerization was completed by dropping continuously at a uniform speed from the dropping nozzle.
[0130]
After the completion of the polymerization, while maintaining the boiling point reflux state for 30 minutes, 20.8 g of 48% NaOH was gradually dropped into the reaction solution with stirring to neutralize. Further, the boiling point reflux state was maintained for 90 minutes to obtain sodium polyacrylate 1-10 (hereinafter referred to as polymer 1-10) having a solid content of 40.1% and a final degree of neutralization of 95%. The weight average molecular weight Mw, hydrogen peroxide content, Hazen, calcium ion trapping ability, and clay dispersing ability of the obtained polymer 1-10 were measured. Table 1 shows the results.
(Example 1-11)
To a 2.5-liter SUS separable flask equipped with a thermometer, a stirrer, and a reflux condenser, 272.3 g of pure water was initially charged, and the temperature of the pure water was raised to a boiling point reflux state with stirring. Then, while maintaining the reflux state under stirring, 450.0 g of 80% AA was added to 35% H for 240 minutes from the start of polymerization.₂O₂  57.2 g of 15% NaPS over 8 minutes from the start of polymerization, 83.3 g of 15% NaPS over 250 minutes from the start of polymerization, and 485.0% NaOH, 375.0 g over 240 minutes from the start of polymerization. The polymerization was completed by dropping continuously at a uniform speed from the dropping nozzle.
[0131]
After completion of the polymerization, 25.0 g of 48% NaOH was gradually added dropwise to the reaction solution with stirring while maintaining the boiling point reflux state for 30 minutes for neutralization. Further, the boiling point reflux state was maintained for 90 minutes to obtain sodium polyacrylate 1-11 (hereinafter, referred to as polymer 1-11) having a solid content of 39.6% and a final degree of neutralization of 96%. The weight average molecular weight Mw, hydrogen peroxide content, Hazen, calcium ion trapping ability, and clay dispersing ability of the obtained polymer 1-11 were measured. Table 1 shows the results.
(Example 1-12)
To a 2.5-liter SUS separable flask equipped with a thermometer, a stirrer, and a reflux condenser, 258.8 g of pure water was initially charged, and the pure water was heated to a boiling point reflux state with stirring. Then, while maintaining the reflux state under stirring, 450.0 g of 80% AA was added to 35% H for 240 minutes from the start of polymerization.₂O₂  58.9 g of 15% NaPS over 15 minutes from the start of polymerization over 165 minutes, 102.8 g of 15% NaPS over 250 minutes from the start of polymerization, and 485.0% NaOH at 375.0 g over 240 minutes from the start of polymerization. The polymerization was completed by dropping continuously at a uniform speed from the dropping nozzle.
[0132]
After completion of the polymerization, 25.0 g of 48% NaOH was gradually added dropwise to the reaction solution with stirring while maintaining the boiling point reflux state for 30 minutes for neutralization. Further, the boiling point reflux state was maintained for 90 minutes to obtain sodium polyacrylate 1-12 (hereinafter referred to as polymer 1-12) having a solid content of 39.6% and a final degree of neutralization of 96%. The weight average molecular weight Mw, hydrogen peroxide content, Hazen, calcium ion trapping ability, and clay dispersing ability of the obtained polymer 1-12 were measured. Table 1 shows the results.
(Example 1-13)
1384.8 g of pure water was initially charged into a 2.5-liter SUS separable flask equipped with a thermometer, a stirrer, and a reflux condenser, and the temperature of the pure water was raised to a boiling point reflux state with stirring. Next, while maintaining the reflux state under stirring, 450.0 g of 80% AA was added to 35% H from 5 minutes after the initiation of polymerization to 235 minutes.₂O₂  61.1 g were separately separated from 180% of the polymerization for 180 minutes, 106.7 g of 15% NaPS over 250 minutes from the start of polymerization, and 375.0 g of 48% NaOH from 235 minutes after 5 minutes from the start of polymerization. The polymerization was completed by dropping continuously at a uniform speed from the dropping nozzle.
[0133]
After completion of the polymerization, 25.0 g of 48% NaOH was gradually added dropwise to the reaction solution with stirring while maintaining the boiling point reflux state for 30 minutes for neutralization. Further, the boiling point reflux state was maintained for 90 minutes to obtain sodium polyacrylate 1-13 (hereinafter referred to as polymer 1-13) having a solid content of 20.6% and a final degree of neutralization of 96%. The weight average molecular weight Mw, hydrogen peroxide content, Hazen, calcium ion trapping ability, and clay dispersing ability of the obtained polymer 1-13 were measured. Table 1 shows the results.
(Example 1-14)
179.1 g of pure water was initially charged into a 2.5-liter SUS separable flask equipped with a thermometer, a stirrer, and a reflux condenser, and the temperature of the pure water was raised to a boiling point reflux state with stirring. Then, while maintaining the reflux state under stirring, 418.5 g of 80% AA was added from 5 minutes after the initiation of polymerization to 175 minutes, and 89.2 g of 37% SA was added from 5 minutes after the initiation of polymerization to 175 minutes. 35% H₂O₂  68.6 g were separated over 120 minutes from the start of polymerization, 133.3 g of 15% NaPS over 190 minutes from the start of polymerization, and 262.4 g of 48% NaOH over 175 minutes from 5 minutes after the start of polymerization. The polymerization was completed by dropping continuously at a uniform speed from the dropping nozzle.
[0134]
After completion of the polymerization, 104.2 g of 48% NaOH was gradually dropped into the reaction solution with stirring while maintaining the boiling point reflux state for 30 minutes for neutralization. Further, the boiling point reflux state was maintained for 60 minutes to obtain sodium polyacrylate 1-14 (hereinafter referred to as polymer 1-14) having a solid content of 40.1% and a final degree of neutralization of 95%. The weight average molecular weight Mw, hydrogen peroxide content, Hazen, calcium ion trapping ability, and clay dispersing ability of the obtained polymer 1-14 were measured. Table 1 shows the results.
(Example 1-15)
231.8 g of pure water was initially charged into a 2.5-liter SUS separable flask equipped with a thermometer, a stirrer, and a reflux condenser, and the temperature of the pure water was raised to a boiling point reflux state with stirring. Then, under stirring, while maintaining the temperature of the pure water at 98 ° C., 450.0 g of 80% AA was added to 35% H from 5 minutes after the initiation of polymerization to 175 minutes.₂O₂85.7 g of the 15% NaPS over 6 minutes from the initiation of polymerization, 66.7 g of 15% NaPS over 190 minutes from the initiation of polymerization, and 375.0 g of 48% NaOH over 5 minutes after the initiation of polymerization over 175 minutes. The polymerization was completed by dropping continuously at a uniform speed from the dropping nozzle.
[0135]
After the completion of the polymerization, while maintaining the temperature of the reaction solution at 98 ° C. for 30 minutes, 20.8 g of 48% NaOH was gradually dropped into the reaction solution with stirring to neutralize. The temperature was further raised to the boiling point reflux state and maintained for 60 minutes to obtain sodium polyacrylate 1-15 (hereinafter referred to as polymer 1-15) having a solid content of 40.3% and a final degree of neutralization of 95%. . The weight average molecular weight Mw, hydrogen peroxide content, Hazen, calcium ion trapping ability, and clay dispersing ability of the obtained polymer 1-15 were measured. Table 1 shows the results.
[0136]
Table 2 summarizes the reaction conditions in each of the above examples.
[0137]
[Table 1]

[0138]
[Table 2]

[0139]
As is clear from the results in Table 1, the polymers 1-1 to 1-15 according to the present invention all have a weight average molecular weight of 20,000 or less, and have a low molecular weight and , DispersionAnd clay dispersibility under high hardness waterIt was found that a good polymer was obtained. Further, the Hazen of each polymer aqueous solution was 300 or less, and it was found that a polymer having a very good color tone could be obtained.
[0140]
Hereinafter, in order to evaluate the use of the polymer of the present invention obtained in Examples 1-1 to 1-15 as a detergent composition, the ability to prevent re-contamination was measured by the following method. . Table 3 summarizes the results.
[0141]
<Re-contamination prevention ability>
{Circle around (1)} A JIS-L0803 cotton cloth obtained from the Laundry Science Association was cut into 5 cm × 5 cm to prepare a white cloth. The whiteness of the white cloth was measured in advance by using a colorimetric colorimeter ND-1001DP manufactured by Nippon Denshoku Industries Co., Ltd. in terms of reflectance.
[0142]
{Circle around (2)} Pure water was added to 0.294 g of calcium chloride dihydrate to make 5000 g, and hard water was prepared. Hard water and tap water for rinsing were placed in a thermostat at 25 ° C.
[0143]
{Circle around (3)} The turgot meter was set at 25 ° C., 1 L of hard water and 1 g of clay were put in a pot, and stirred at 100 rpm for 1 minute. Thereafter, 10 white cloths were put and stirred at 100 rpm for 1 minute.
[0144]
{Circle around (4)} 4 g of a 5% aqueous sodium carbonate solution, 4 g of a 5% aqueous solution of sodium linear alkylbenzene sulfonate (hereinafter abbreviated as LAS), 0.15 g of zeolite, and 5 g of a 1% polymer aqueous solution in terms of solid content are put into a pot, and 100 rpm. For 10 minutes.
[0145]
{Circle around (5)} The water on the white cloth was drained by hand, and 1 L of tap water at 25 ° C. was put into a pot and stirred at 100 rpm for 2 minutes. This was done twice.
[0146]
(6) The steps (3) to (5) were repeated three times.
[0147]
{Circle around (7)} After applying a cloth to the white cloth and drying it while wrinkling with an iron, the whiteness of the white cloth was measured again by the reflectance using the above colorimeter.
[0148]
{Circle around (8)} From the above measurement results, the recontamination prevention rate was determined by the following equation (Equation 2).
[0149]
(Equation 2)

[0150]
[Table 3]

[0151]
As is clear from Table 3, the polymer obtained by the production method of the present invention has an excellent ability to prevent re-contamination.
[0152]
Hereinafter, in order to further evaluate the use of the polymer of the present invention obtained in Examples 1-1 to 1-15 as a detergent composition, the cleaning ability was measured by the following method. Table 4 summarizes the results.
[0153]
<Cleaning ability>
{Circle around (1)} A JIS-L0803 cotton cloth obtained from the Laundry Science Association was cut into 5 cm × 5 cm to prepare a white cloth. Wet artificially stained cloth was also obtained from the Laundry Science Association. The whiteness and the contaminated cloth were measured in advance for reflectance using a colorimetric colorimeter ND-1001DP manufactured by Nippon Denshoku Industries Co., Ltd. in terms of reflectance.
[0154]
{Circle around (2)} Pure water was added to 0.294 g of calcium chloride dihydrate to make 5000 g, and hard water was prepared. Hard water and tap water for rinsing were placed in a thermostat at 25 ° C.
[0155]
{Circle around (3)} The tergot meter was set at 25 ° C., 500 ml of hard water, 5 contaminated cloths and 5 white cloths were placed in a pot, and stirred at 100 rpm for 1 minute.
[0156]
{Circle around (4)} 2 g of a 5% aqueous sodium carbonate solution, 2 g of a 5% aqueous LAS solution, 0.075 g of zeolite, and 10 g of a 1% polymer aqueous solution in terms of solid content were placed in a pot and stirred at 100 rpm for 10 minutes.
[0157]
{Circle around (5)} The water of the white cloth and the contaminated cloth was drained by hand, 500 ml of tap water at 25 ° C. was put into a pot, and the mixture was stirred at 100 rpm for 2 minutes. This was done twice.
[0158]
{Circle around (6)} The white cloth and the contaminated cloth were applied to each other, and dried while the wrinkles were stretched with an iron. Then, the whiteness of the white cloth and the contaminated cloth was measured again by the reflectance using the above colorimeter.
[0159]
{Circle around (7)} From the above measurement results, the cleaning rate was determined by the following equation (Equation 3).
[0160]
(Equation 3)

[0161]
[Table 4]

[0162]
As is clear from Table 4, the polymer obtained by the production method of the present invention has excellent cleaning ability.
[0163]
By combining the results of Tables 3 and 4, it became clear that the detergent composition of the present invention was very excellent.
[0164]
In the following, with respect to the polymers of the present invention obtained in Examples 1-1 to 1-15, in order to evaluate the use as a water treatment agent, the ability to prevent calcium carbonate scale was measured by the following method. went. Table 5 summarizes the results.
[0165]
<Calcium carbonate scale prevention ability>
{Circle around (1)} First, a 1.56% aqueous solution of calcium chloride dihydrate and a 3.0% aqueous sodium hydrogen carbonate solution, and an aqueous solution of a polymer having a solid content of 0.2% were prepared.
[0166]
{Circle around (2)} Next, 170 g of pure water was placed in a glass bottle having a capacity of 225 ml, 10 g of a 1.56% calcium chloride dihydrate aqueous solution, 3 g of a 0.2% polymer solution in terms of solid content were mixed, and carbonic acid was further added. 10 g of an aqueous sodium hydrogen solution and 7 g of sodium chloride were added to make the total amount 200 g.
[0167]
{Circle around (3)} The obtained 530 ppm supersaturated aqueous solution of calcium carbonate was sealed and heated at 70 ° C.
[0168]
{Circle around (4)} After cooling, the precipitate was filtered with a 0.1 μm membrane filter, and the filtrate was analyzed according to JIS K0101.
[0169]
(5) From the above measurement results, the calcium carbonate scale inhibition rate (%) was determined by the following equation (Equation 4).
[0170]
(Equation 4)

[0171]
[Table 5]

[0172]
As is clear from Table 5, the polymer obtained by the production method of the present invention has a very excellent scale preventing ability. Therefore, it was found that it can be effectively used as a water treatment agent.
[0173]
In the following, in order to evaluate the use of the polymer of the present invention obtained in Examples 1-1 to 1-15 as a pigment dispersant, an inorganic material was prepared using a B-type viscometer by the following method. The viscosity of the pigment dispersion was measured. Table 6 summarizes the results.
[0174]
<Preparation of dispersion and measurement of its viscosity>
{Circle around (1)} First, a 10 wt% polymer aqueous solution was prepared.
[0175]
{Circle around (2)} Next, 150 g of pure water was placed in a 600 ml plastic container, and 70 g of light calcium carbonate was stirred with a TK homomixer manufactured by Tokushu Kika Kogyo Co., Ltd. using a lab disper MR-L type at 1000 rpm. 105 g of heavy calcium carbonate and 175 g of alpha coat were gradually added in this order. During the addition, if it became difficult to disperse the pigment, the above 10 wt% polymer aqueous solution was appropriately added.
[0176]
{Circle around (3)} After all the pigments were added, the above 10 wt% aqueous polymer solution was added to a total amount of 10.5 g, and the mixture was further stirred at 3000 rpm for 15 minutes.
[0177]
{Circle around (4)} After stirring, the mixture was placed in a thermostat at 25 ° C. for 30 minutes. Then, the viscosity was measured by rotating the rotor for 3 minutes using a B-type viscometer.
[0178]
[Table 6]

[0179]
As is evident from Table 6, the polymer obtained by the production method of the present invention has very excellent inorganic pigment dispersing ability. Therefore, it turned out that it can also be used effectively as a pigment dispersant.
[0180]
【The invention's effect】
According to the present invention, by controlling the degree of neutralization to 99 mol% or less during polymerization, corrosion of production equipment can be avoided, and a low-molecular-weight polymer can be efficiently produced at a high concentration. Also, by using a combination of a persulfate and hydrogen peroxide, it is possible to significantly reduce the amount of addition and produce a high-purity low-molecular-weight polymer with good purity. Furthermore, the polymerization termination reaction can be suppressed by defining the hydrogen peroxide supply conditions, and a low molecular weight polymer can be obtained.
[0181]
The low molecular weight polymer obtained by the method of the present invention can be suitably used for applications such as detergent compositions, water treatment agents, and pigment dispersants.

Claims (7)

A monocarboxylic acid (salt) having 3 to 6 carbon atoms, a monoethylenically unsaturated monomer (a) of 100 to 95 mol% and a monoethylenically unsaturated monomer copolymerizable with the monomer (a) ( b) a monomer component consisting of 0 to 5 mol% (the total amount of (a) and (b) is 100 mol%) in the presence of an alkali substance, using a polymerization catalyst and at a high concentration; An aqueous solution polymerization method, wherein persulfate and hydrogen peroxide are used in combination as the polymerization catalyst, and the total amount of the alkaline substance is necessary to neutralize all the acid groups of the monomer component. with a 99 mol% of the amount or less, the dropping of the hydrogen peroxide as the ends earlier than 10 minutes from the dropping end time of the monomer component, and the monomer (a) and monomer (b ) Is substantially 70% by weight or more based on the total amount used. Is characterized by adding to the reaction system by dropwise addition continue to method for producing a low molecular weight (meth) acrylic acid (salt) polymer. If the final concentration of the polymer is less than 20,000, the weight average molecular weight is not less than the value obtained by multiplying the weight average molecular weight by 0.002, and if the weight average molecular weight is not less than 20,000, the final concentration is not less than the square root of the value obtained by multiplying the weight average molecular weight by 0.08. The method for producing a low molecular weight (meth) acrylic acid (salt) polymer according to claim 1 . The method for producing a low molecular weight (meth) acrylic acid (salt) polymer according to claim 1 , wherein the final concentration of the polymer is 30% by weight or more. Obtained by the method according to any one of claims 1 to 3, low molecular weight (meth) acrylic acid (salt) polymer. A monocarboxylic acid (salt) having 3 to 6 carbon atoms, a monoethylenically unsaturated monomer (a) of 100 to 95 mol%, and a monoethylenically unsaturated monomer copolymerizable with the monomer (a) ( b) A low molecular weight (meth) acrylic acid (salt) polymer obtained by polymerizing a monomer component consisting of 0 to 5 mol% (the total amount of (a) and (b) is 100 mol%). Having a weight average molecular weight of 1,000 to 30,000, a dispersity of 1.5 to 5.0, a hydrogen peroxide concentration of a 40% by weight aqueous solution of the polymer of 5 to 500 ppm, Ri der Hazen 300 following 40 wt% aqueous solution, clay dispersibility in high-hardness water, characterized in der Rukoto 0.47 or more, a low molecular weight (meth) acrylic acid (salt) polymer. The low molecular weight (meth) acrylic acid (salt) -based polymer according to claim 5, wherein the clay dispersing ability under high hardness water is 0.47 to 0.60. A detergent composition comprising the low molecular weight (meth) acrylic acid (salt) -based polymer according to any one of claims 4 to 6 .