JP3707933B2 - Vinyl chloride resin granules for paste processing and manufacturing method thereof - Google Patents
Vinyl chloride resin granules for paste processing and manufacturing method thereof Download PDFInfo
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Description
【0001】
【発明の属する技術分野】
本発明は、ペースト加工用塩化ビニル系樹脂顆粒及びその製造方法に関する。さらに詳しくは、本発明は、粉体流動性に優れ、ペースト調製に際して可塑剤への分散性の良好なペースト加工用塩化ビニル系樹脂顆粒及びその製造方法に関するものである。
【0002】
【従来の技術】
ペースト加工用塩化ビニル系樹脂を梱包している袋の開袋時の粉塵の発生などによる作業環境の悪化を防止するとともに、従来は困難であったペースト加工用塩化ビニル系樹脂粉体の自動計量供給を可能にするために、乳化重合又は微細懸濁重合して得られる一次粒径0.1〜5μm程度の塩化ビニル系重合体の水性分散液を噴霧乾燥処理して造粒し、平均粒径50〜250μm程度の塩化ビニル系樹脂顆粒とする方法が知られている。
この塩化ビニル系樹脂顆粒は、ペースト加工に際しては、そのまま粉砕することなく用いられる。すなわち、ペースト加工用塩化ビニル系樹脂顆粒は、可塑剤と、その他必要に応じて熱安定剤や充填剤などの配合剤と混合してプラスチゾルとされる。
このペースト加工用塩化ビニル系樹脂顆粒の製造方法として、様々な提案がなされている。例えば、特開平2−133410号公報には、噴霧乾燥において入口空気温度100℃以下、出口空気温度50℃以下で運転して、粉体特性が良好でかさ比重の大きい塩化ビニル樹脂顆粒として、全質量中に占める直径20μm以上の球状顆粒の割合が60重量%以上である球状塩化ビニル樹脂顆粒が提案されている。
また、特開平2−225529号公報には、流れ性がよく、微粉が少なく粉塵発生の問題も少ない粒子状ペースト加工用塩化ビニル樹脂の製造法として、絶対湿度0.007〜0.014kg水/kg空気の空気を用い、乾燥用空気入口温度を100℃以下、乾燥用空気出口温度を53℃以下として粒子状樹脂を得る方法が提案されている。しかし、これらの製造法は、いずれも低温で乾燥を行うために生産性が著しく低く、噴霧滞空時間を長く確保するために、乾燥機の大型化やエネルギーコストの増大を伴うなどの問題を有している。
【0003】
【発明が解決しようとする課題】
本発明は、このような事情のもとで、粉体流動性に優れ、かつペースト調製に際して可塑剤への分散性の良好なペースト加工用塩化ビニル系樹脂顆粒を効率よく製造する方法、及びこの方法により得られた上記性状を有するペースト加工用塩化ビニル系樹脂顆粒を提供することを目的としてなされたものである。
【0004】
【課題を解決するための手段】
本発明者らは、前記の好ましい性状を有するペースト加工用塩化ビニル系樹脂顆粒の製造方法について鋭意研究を重ねた結果、特定の粒径範囲と粒径分布を有する塩化ビニル系重合体を所定の濃度で含有する水性分散液を、好ましくは100℃より高い温度の乾燥用加熱空気を用いて噴霧乾燥処理することにより、その目的を達成しうることを見出し、この知見に基づいて本発明を完成するに至った。
すなわち、本発明は、
(1)レーザー回折法の測定による重合体粒子の粒径が、少なくとも0.2〜5μmの範囲に連続的に分布し、頻度に二つの極大値を有し、小粒子の群の極大値を与える粒径が0.2〜0.6μmの範囲に、大粒子の群の極大値を与える粒径が1.0〜4.0μmの範囲にそれぞれあり、全体の平均粒径が0.6〜3.0μmであって、粒径0.1〜0.7μmの粒子と粒径0.8〜5μmの粒子との比率が5〜40重量%対60〜95重量%である粒径分布を有し、該樹脂100重量部とジ−2−エチルヘキシルフタレート60重量部とを混合して得られるペーストの未分散粒子率が0.1重量%以下で、セーバーズ流出量が30g/100秒以上であることを特徴とするペースト加工用塩化ビニル系樹脂顆粒、
(2)レーザー回折法の測定による重合体粒子の粒径が、少なくとも0.2〜5μmの範囲に連続的に分布し、頻度に二つの極大値を有し、小粒子の群の極大値を与える粒径が0.2〜0.6μmの範囲に、大粒子の群の極大値を与える粒径が1.0〜4.0μmの範囲にそれぞれあり、全体の平均粒径が0.6〜3.0μmであって、粒径0.1〜0.7μmの粒子と粒径0.8〜5μmの粒子との比率が5〜40重量%対60〜95重量%である粒径分布を有する塩化ビニル系重合体55〜75重量%を含有する水性分散液を噴霧乾燥処理することを特徴とするペースト加工用塩化ビニル系樹脂顆粒の製造方法、及び、
(3)噴霧乾燥処理に100℃より高い温度の乾燥用加熱空気を使用する第(2)項記載のペースト加工用塩化ビニル系樹脂顆粒の製造方法、
を提供するものである。
さらに、本発明の好ましい態様として、
(4)噴霧乾燥処理に供する塩化ビニル系重合体の水性分散液が、微細懸濁重合により得られた水性分散液と乳化重合により得られた水性分散液との混合物である第(2)項又は第(3)項記載のペースト加工用塩化ビニル系樹脂顆粒の製造方法、
を挙げることができる。
【0005】
【発明の実施の形態】
本発明のペースト加工用塩化ビニル系樹脂顆粒の製造方法は、塩化ビニル系重合体の水性分散液を噴霧乾燥処理する方法であって、上記塩化ビニル系重合体の水性分散液としては、下記の粒径及び粒度分布を有する塩化ビニル系重合体を含有するものを用いることが必要である。
まず、該塩化ビニル系重合体は、レーザー回折法の測定による重合体粒子の粒径が、少なくとも0.2〜5μmの範囲に連続的に分布し、頻度に二つの極大値を有し、小粒子の群の極大値を与える粒径が0.2〜0.6μmの範囲に、大粒子の群の極大値を与える粒径が1.0〜4.0μmの範囲にそれぞれあることが必要である。次に、全体の平均粒径が0.6〜3.0μm、好ましくは1.0〜2.5μmであり、粒径0.1〜0.7μmの粒子と粒径0.8〜5μmの粒子との比率が5〜40重量%対60〜95重量%、好ましくは15〜30重量%対70〜85重量%である粒径分布を有することが必要である。ここにおいて、粒径0.1〜0.7μmの粒子の比率と粒径0.8〜5μmの粒子の比率との合計は100重量%である。粒径分布及び平均粒径が上記で規定する範囲を逸脱するものでは、所望の性状を有する塩化ビニル系樹脂顆粒が得られない。なお、本発明におけるレーザー回折法による粒径分布及び平均粒径の測定法は、後で示す。
さらに、本発明において用いられる塩化ビニル系重合体の水性分散液は、前記の性状を有する塩化ビニル系重合体を55〜75重量%の濃度で含有することが必要である。この塩化ビニル系重合体の含有量が上記範囲を逸脱すると所望の性状を有する塩化ビニル系樹脂顆粒が得られない。
本発明方法により製造されるペースト加工用塩化ビニル系樹脂顆粒は、噴霧液滴の水分が乾燥により除去されることによって形成される重合体粒子の球状の集合体である。ここに球状とは、真球状のものに限られず、長軸:短軸の比が1:1〜1:0.8程度の回転楕円体や回転楕円体のある程度変形したものをも含むものである。球状の重合体粒子を用いることにより、顆粒の流動性を良好なものとすることができる。
【0006】
本発明方法に用いる塩化ビニル系重合体の水性分散液の調製方法としては、前記の粒径分布及び粒径を有する塩化ビニル系重合体を所定の濃度で含有する水性分散液が得られる方法であればよく、特に制限はないが、例えば以下に示す方法が好ましく用いられる。すなわち、塩化ビニル単独又は塩化ビニルを主体とし、これと共重合しうる共単量体との混合物を微細懸濁重合し、得られた塩化ビニル系重合体の水性分散液に、上記と同様の単量体を乳化重合して得られた塩化ビニル系重合体の水性分散液を混合することにより、所望の塩化ビニル系重合体の水性分散液を、効率よく調製することができる。
なお、上記乳化重合には播種乳化重合が含まれ、微細懸濁重合には、播種微細懸濁重合が含まれるものとする。
本発明方法において、塩化ビニルを主体としこれと共重合し得る共単量体との混合物は、混合物中の塩化ビニルの量が50重量%以上であることが好ましく、75重量%以上であることがより好ましい。塩化ビニルと共重合し得る共単量体としては、例えば、エチレン、プロピレンなどのオレフィン系化合物;酢酸ビニル、プロピオン酸ビニルなどのビニルエステル;アクリル酸、メタクリル酸などの不飽和モノカルボン酸;アクリル酸メチル、アクリル酸エチル、アクリル酸−n−ブチル、アクリル酸−2−ヒドロキシエチル、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸−N,N−ジメチルアミノエチルなどの不飽和モノカルボン酸エステル;アクリルアミド、メタクリルアミドなどの不飽和アミド;アクリロニトリル、メタクリロニトリルなどの不飽和ニトリル;マレイン酸、フマール酸などの不飽和ジカルボン酸;これらのエステル及びこれらの無水物;N−置換マレイミド類;ビニルメチルエーテル、ビニルエチルエーテルなどのビニルエーテル;さらに塩化ビニリデンなどのビニリデン化合物などを挙げることができる。
【0007】
塩化ビニル単独又は塩化ビニルを主体としこれと共重合し得る共単量体との混合物を微細懸濁重合するに際しては、まず水性媒体中に、塩化ビニル単独又は塩化ビニルを主体としこれと共重合し得る共単量体との混合物、油溶性重合開始剤、乳化剤、必要に応じて高級アルコール、高級脂肪酸及びそのエステル、塩素化パラフィンなどの分散助剤、その他の添加剤を加えてプレミックスし、ホモジナイザにより均質化処理して油滴の粒径調節を行う。ホモジナイザとしては、例えば、コロイドミル、振動撹拌機、二段式高圧ポンプなどを用いることができる。均質化処理した液を重合器に送り、緩やかに撹拌しながら重合器内の温度を上げて重合反応を開始し、以後所定の転化率に達するまで重合を行うことができる。重合温度は、30〜80℃であることが好ましい。播種微細懸濁重合においては、重合器に純水、粒子中に重合開始剤が残存する種子重合体などを仕込み、重合器内の脱気あるいは必要に応じて窒素などの不活性気体による置換を行ったのち、塩化ビニル単独又は塩化ビニルを主体としこれと共重合し得る共単量体との混合物を仕込み、緩やかに撹拌しながら重合器内の温度を上げて重合を進めることができる。重合温度は、30〜80℃であることが好ましい。播種微細懸濁重合の場合は、重合開始剤を新たに添加しなくてもよい。
【0008】
微細懸濁重合に使用する油溶性重合開始剤としては、例えば、アセチルパーオキシド、3,5,5−トリメチルヘキサノイルパーオキシド、ラウロイルパーオキシド、ベンゾイルパーオキシド、ナフトイルパーオキシドなどのジアシルパーオキシド;メチルエチルケトンパーオキシドなどのケトンパーオキシド;t−ブチルパーオキシピバレート、テトラメチルブチルネオデカネート、クミルパーオキシネオデカネートなどのパーオキシエステル;ジイソプロピルパーオキシジカーボネート、ジエチルヘキシルパーオキシジカーボネートなどのパーオキシジカーボネート;アセチルシクロヘキシルスルホニルパーオキシドなどのスルホニルパーオキシドなどの有機過酸化物;2,2'−アゾビスイソブチロニトリル、2,2'−アゾビス(2−メチルブチロニトリル)、2,2'−アゾビス(2,4−ジメチルバレロニトリル)、2,2'−アゾビス(4−メトキシ−2,4−ジメチルバレロニトリル)などのアゾ化合物などを挙げることができる。また使用する乳化剤としては、アニオン性界面活性剤又はノニオン性界面活性剤が挙げられる。ここで、アニオン性界面活性剤としては、例えば、ドデシルベンゼンスルホン酸ナトリウムなどのアルキルベンゼンスルホン酸塩;ラウリル硫酸ナトリウム、テトラデシル硫酸ナトリウムなどのアルキル硫酸塩;ジオクチルスルホコハク酸ナトリウム、ジへキシルスルホコハク酸ナトリウムなどのスルホコハク酸塩;ラウリン酸ナトリウム、半硬化牛脂脂肪酸カリウムなどの脂肪酸塩;ポリオキシエチレンラウリルエーテルサルフェートナトリウム塩、ポリオキシエチレンノニルフェニルエーテルサルフェートナトリウム塩などのエトキシサルフェート塩;アルカンスルホン酸塩;アルキルエーテル燐酸エステルナトリウム塩などを挙げることができる。また、ノニオン性界面活性剤としては、例えば、ポリオキシエチレンノニルフェニルエーテル、ポリオキシエチレンソルビタンラウリルエステルなどを挙げることができる。乳化剤の使用量は、適用される重合法により異なるが、通常は単量体100重量部当たり0.2〜2.5重量部であることが好ましい。
【0009】
この微細懸濁重合により、一次粒子の粒径が0.05〜5μm程度の広い範囲に連続して分布し、山形の頻度分布を有する球形の重合体粒子の塩化ビニル系重合体の水性分散液を得ることができる。また、播種微細懸濁重合により、一次粒子の粒径が0.3〜10μm程度の広い範囲に連続して、頻度が山形の粒径分布を有する球形の重合体粒子の塩化ビニル系重合体の水性分散液を得ることができる。ここで、本発明においては、塩化ビニル系重合体の粒径分布や平均粒径をレーザー回折法により測定する。
一方、塩化ビニル単独又は塩化ビニルを主体としこれと共重合し得る共単量体との混合物を乳化重合するに際しては、重合器に純水、乳化剤、水溶性重合開始剤などを仕込み、重合器内の脱気あるいは必要に応じて窒素などの不活性気体による置換を行い、塩化ビニル単独又は塩化ビニルを主体としこれと共重合し得る共単量体との混合物を仕込み、撹拌して単量体を可溶化した乳化剤ミセル層を形成しつつ、重合器内の温度を上げて重合を進める。反応速度や粒子径の制御のために、乳化剤、開始剤、還元剤などを重合反応中に添加することもできる。重合温度は30〜80℃の範囲が好ましい。
この乳化重合により、平均粒径が0.2〜0.7μm程度で、分布範囲が平均粒径±0.2〜0.4μmの単一モードで、狭い粒径分布をもつ重合体の水性分散液を得る。
播種乳化重合法においては、乳化重合により得られた重合体を種子として、水媒体中でこれを単量体の重合により肥大化させ、重合体粒子を安定化するためのアニオン性界面活性剤からなる乳化剤を、重合体粒子表面を覆うに必要な量を超えないように重合反応の進行に調和させて添加しつつ、水溶性重合開始剤を用いて重合する。重合温度は、30〜80℃の範囲が好ましい。この播種乳化重合により、種子を肥大化した平均粒径が0.9〜2.0μm程度で、分布範囲が平均粒径±0.3〜0.5μmの1つの尖鋭な粒径頻度分布をもつ大粒子が生成する。この大粒子の他に、平均粒径0.2〜0.4μm程度の副生した小粒子を20重量%以下の割合で含んで2モードの粒径分布を有することもしばしばある。
【0010】
使用する乳化剤としては、前記の微細懸濁重合に使用するものと同様のものを挙げることができる。また、使用する水溶性重合開始剤としては、例えば過硫酸カリウム、過硫酸アンモニウム、過酸化水素などの水溶性過酸化物、これらの過酸化物又はクメンヒドロパーオキシド、t−ブチルヒドロパーオキシドなどのヒドロパーオキシドに、酸性亜硫酸ナトリウム、亜硫酸アンモニウム、アスコルビン酸、第1鉄イオンのエチレンジアミン四酢酸ナトリウム錯塩、ピロリン酸第1鉄などの還元剤を組み合わせたレドックス系開始剤、2,2'−アゾビス(2−メチルプロピオンアミジン)二塩酸塩などの水溶性アゾ化合物などを挙げることができる。
乳化重合、播種乳化重合、微細懸濁重合又は播種微細懸濁重合によって得られる塩化ビニル系重合体の水性分散液の固形分濃度は、通常は35〜55重量%程度である。このような水性分散液は、限外ろ過や蒸発により40〜65重量%程度に濃縮することができるが、60重量%以上に濃縮すると水性分散液の流動性が変化しやすいので、通常は60重量%より低い濃度の水性分散液を噴霧乾燥処理に供していた。しかし、本発明方法においては、塩化ビニル系重合体に本発明に係る特定の粒径分布をもたせることにより、重合体粒子をより密な充填ができるためか、濃縮しうる濃度の上限を引き上げることができる。例えば、微細懸濁重合により得られた粒径0.05〜5μm程度の広い山形の粒径分布を有する重合体粒子を含有する水性分散液か、又は播種微細懸濁重合により得られた粒径0.3〜10μm程度の広い山形の粒径分布を有する重合体粒子を含有する水性分散液と、乳化重合により得られた粒径0.2〜0.3μm程度の狭い粒径分布を有する重合体粒子を含有する水性分散液とを、重合体の重量比で、60:40ないし90:10程度の割合で混合することにより、本発明に係る特定の粒径分布を有する重合体の水性分散液を得ることができる。また、微細懸濁重合に際して、分散助剤又は重合開始剤をエマルジョン状で、単量体や水と共にプレミックスしてホモジナイズする方法によっても、粒径が0.2〜約10μmに連続して分布し、0.2〜0.4μm程度の位置と、0.5〜3μm程度の位置とにモードを有する、本発明に係る特定の粒径分布をもつ重合体の水性分散液を得ることができる。あるいは、特開平10−87707号公報に開示されているような、微細懸濁重合による重合体水性分散液に対し、乳化重合による重合体分散液を、重合体重量比0.5〜2で混合したものを種子として肥大化重合することによっても、本発明に係る特定の粒径分布をもつ重合体の調製を図ることができる。このような特定の粒径分布をもつ重合体であれば、固形分濃度を55〜75重量%、好ましくは60〜70重量%に濃縮しても流動性のある重合体水性分散液を調製することができる。
【0011】
この塩化ビニル系重合体の水性分散液の濃縮方法としては、例えば透析膜や限外ろ過膜を用いた濃縮、真空蒸発器による濃縮、薄膜蒸発器による濃縮などを挙げることができる。これらの中で、膜濃縮に使用する膜には特に制限はなく、例えば、酢酸セルロース系膜、ポリスルホン系膜、ポリアミド系膜、ポリアクリロニトリル系膜、フッ素樹脂系膜などを挙げることができる。
本発明方法においては、上記の特定の粒径分布を有する塩化ビニル系重合体の固形分濃度が55〜75重量%、好ましくは60〜70重量%の塩化ビニル系重合体の水性分散液を噴霧乾燥処理する。使用する噴霧乾燥機に特に制限はなく、例えば、噴霧形式としては、回転円盤型アトマイザー、二流体ノズル型アトマイザー、加圧ノズル型アトマイザーなどを挙げることができるが、これらの中で回転円盤式アトマイザーは、水性分散液の流量、密度、粘度などの変動に広く対応できるので好適に使用することができる。熱風と液滴群の接触方式にも特に制限はないが、併流方式が樹脂顆粒の熱履歴分布を小さくする上で好ましい。乾燥用空気は、大気から採取することができ、ことさらに湿度の調整を行う必要はないが、調湿を制限するものではない。乾燥用空気の入口温度は高いほど乾燥能率の上昇が望めるが、200℃を超えると樹脂顆粒のゾル分散性が悪化する。しかし、従来技術のように100℃以下の低い温度が必須ではなくて、100℃より高く200℃以下でよく、特に、110〜170℃の範囲が好ましい。また、乾燥用空気の出口温度は、40〜70℃の範囲が好ましく、45〜55℃の範囲がより好ましい。乾燥の程度は、乾燥された顆粒に含まれる水分が0.05〜1.5重量%であることが好ましく、0.1〜1.0重量%であることがより好ましい。乾燥用空気の出口温度と、乾燥された顆粒の水分率は、塩化ビニル系重合体の水性分散液の供給速度と、乾燥用熱風の温度と風量を制御することにより調整することができる。噴霧液滴径は、塩化ビニル系重合体の水性分散液の供給速度や固形分濃度と、回転円盤型アトマイザーでは円盤回転数により、二流体ノズル型アトマイザーではアトマイズ空気圧と風量により、加圧ノズル型アトマイザーでは圧力を主たる因子として制御することができる。塩化ビニル系重合体の水性分散液の噴霧乾燥により、通常は平均粒径20〜150μmの顆粒を得ることができる。
【0012】
本発明方法においては、固形分濃度が55〜75重量%、好ましくは60〜70重量%の塩化ビニル系重合体の水性分散液を噴霧乾燥処理することにより、高温の乾燥用空気を用いても、粉体流動性に優れるとともに、ペースト調製に際して可塑剤への分散性の良好な塩化ビニル系樹脂顆粒を得ることができる。本発明方法により製造されるペースト加工用塩化ビニル系樹脂顆粒の可塑剤への分散性が良好である理由は明らかではないが、次のような機構によるものであろうと推定される。すなわち、噴霧乾燥機において噴霧された水性分散液の液滴から乾燥の過程で水分が蒸発するに際し、液滴の内部から液滴の表面に水が移動するとき、水性分散液の固形分濃度が低い場合は、粒径0.05〜0.2μm程度の微細粒子が、水の動きに乗って液滴表面に配列する。表面が微細粒子で覆われた樹脂顆粒は、乾燥時の加熱により堅固な表面が形成され、そのために樹脂顆粒を可塑剤と混合するときほぐれにくくなる。これに対して本発明方法により製造されたペースト加工用塩化ビニル系樹脂顆粒は、噴霧乾燥にかけられる水性分散液の固形分濃度が高いので、液滴の内部の水が液滴表面に移動するときに微細粒子を同伴できるほどの流れがもはや生じがたい。したがって、樹脂顆粒の表面には微細粒子の配列が存在しにくいので、顆粒表面が堅固でなく、顆粒は可塑剤に容易に分散し、後述の実施例において測定法を示す未分散粒子率が0.1重量%以下、好ましくは0.02〜0.08重量%の状態になる。
本発明方法によって得られるペースト加工用塩化ビニル系樹脂顆粒の表面には、熱によって堅固に融着する微粒子層が生じにくいので、噴霧乾燥用空気の入口温度が100℃より高い温度にして乾燥の生産性を上げた操業によっても、可塑剤に対してほぐれやすいのである。
この噴霧乾燥処理により得られた樹脂顆粒には、大きな球状集合粒子や乾燥機内壁などに付着していた粉体層が剥がれて生じた断片など、ペースト加工に用いるには可塑剤にほぐれにくいような粗粒が含まれていることがある。本発明のペースト加工用塩化ビニル系樹脂顆粒の製造方法においては、噴霧乾燥処理に続いてこれらの粗粒を除去するために分級することが好ましい。本発明方法において、分級工程の形式には特に制限はないが、顆粒をこわさないように、振動篩特に超音波振動篩を好適に使用することができる。
また、本発明のペースト加工用塩化ビニル系樹脂顆粒は、表面に微粒子層が生じにくいためか、その上低温乾燥によらずに製造された場合は一層その傾向が大きいが、表面が研磨され難く、そのため乾燥直後の良好な粉体流動性の良さが長く保たれる。嵩密度は0.48〜0.60g/cm3、好ましくは0.50〜0.58g/cm3、安息角は36〜46度、好ましくは39〜45度のものとなる。
【0013】
本発明はまた、前記製造方法により得られた塩化ビニル系樹脂顆粒であって、該塩化ビニル系樹脂顆粒100重量部とジ−2−エチルヘキシルフタレート60重量部とからなるペーストのセーバーズ流出量が30g/100秒以上、好ましくは40g/100秒以上であるペースト加工用塩化ビニル系樹脂をも提供するものである。
このセーバーズ流出量が多いほど、高剪断速度下でのゾル粘度が低いことを示す。なお、上記ペーストのセーバーズ流出量の測定方法は、後で示す。
本発明方法により得られるペースト加工用塩化ビニル系樹脂顆粒を用いてプラスチゾルを調製する方法には特に制限はなく、従来塩化ビニル系樹脂プラスチゾルの調製において慣用されている公知の方法を採用することができる。例えば、ペースト加工用塩化ビニル系樹脂顆粒に、可塑剤及び所望により用いられる各種添加剤成分、例えば、熱安定剤、充填剤、発泡剤、発泡促進剤、界面活性剤、粘度調節剤、接着性付与剤、着色剤、希釈剤、紫外線吸収剤、酸化防止剤、補強剤、その他の樹脂などを配合し、プラネタリーミキサー、ニーダー、ロール、擂潰機などを用いて、均質になるように十分に混練することにより、プラスチゾルを調製することができる。
【0014】
プラスチゾルの調製に用いる可塑剤には特に制限はなく、従来塩化ビニル系樹脂プラスチゾルの可塑剤として慣用されているものを使用することができる。このような可塑剤としては、例えば、ジメチルフタレート、ジエチルフタレート、ジブチルフタレート、ジイソブチルフタレート、ジヘプチルフタレート、ジ−2−エチルヘキシルフタレート、ジ−n−オクチルフタレート、ジノニルフタレート、ジイソデシルフタレート、ジウンデシルフタレート、ジトリデシルフタレート、ジシクロヘキシルフタレート、ブチルベンジルフタレート、ジフェニルフタレート、ジベンジルフタレートなどのフタル酸エステル系可塑剤;ジメチルイソフタレート、ジ−2−エチルヘキシルイソフタレート、ジイソオクチルイソフタレートなどのイソフタル酸エステル系可塑剤;ジ−2−エチルヘキシルテトラヒドロフタレート、ジ−n−オクチルテトラヒドロフタレート、ジイソデシルテトラヒドロフタレートなどのテトラヒドロフタル酸エステル系可塑剤;ジ−n−ブチルアジペート、ジ−2−エチルヘキシルアジペート、ジイソノニルアジペート、ジイソデシルアジペートなどのアジピン酸エステル系可塑剤;ジ−n−ヘキシルアゼレート、ジ−2−エチルヘキシルアゼレート、ジイソオクチルアゼレートなどのアゼライン酸エステル系可塑剤;ジ−n−ブチルセバケート、ジ−2−エチルヘキシルセバケートなどのセバシン酸エステル系可塑剤;ジ−n−ブチルマレエート、ジメチルマレエート、ジエチルマレエート、ジ−2−エチルヘキシルマレエートなどのマレイン酸エステル系可塑剤;ジ−n−ブチルフマレート、ジ−2−エチルヘキシルフマレートなどのフマル酸エステル系可塑剤;トリ−n−ヘキシルトリメリテート、トリ−2−エチルヘキシルトリメリテート、トリ−n−オクチルトリメリテート、トリイソオクチルトリメリテート、トリイソノニルトリメリテート、トリイソデシルトリメリテートなどのトリメリット酸エステル系可塑剤;テトラ−2−エチルヘキシルピロメリテート、テトラ−n−オクチルピロメリテートなどのピロメリット酸エステル系可塑剤;トリエチルシトレート、トリ−n−ブチルシトレート、アセチルトリエチルシトレート、アセチルトリ−2−エチルヘキシルシトレートなどのクエン酸エステル系可塑剤;モノメチルイタコネート、モノブチルイタコネート、ジメチルイタコネート、ジエチルイタコネート、ジブチルイタコネート、ジ−2−エチルヘキシルイタコネートなどのイタコン酸エステル系可塑剤;ブチルオレエート、グリセリルモノオレエート、ジエチレングリコールモノオレエートなどのオレイン酸エステル系可塑剤;メチルアセチルリシノレート、ブチルアセチルリシノレート、グリセリルモノリシノレート、ジエチレングリコールモノリシノレートなどのリシノール酸エステル系可塑剤;n−ブチルステアレート、グリセリンモノステアレート、ジエチレングリコールジステアレートなどのステアリン酸エステル系可塑剤;ジエチレングリコールモノラウレート、ジエチレングリコールジペラルゴネート、ペンタエリスリトールの各種脂肪酸エステルなどのその他の脂肪酸エステル系可塑剤;トリエチルホスフェート、トリブチルホスフェート、トリ−2−エチルヘキシルホスフェート、トリブトキシエチルホスフェート、トリフェニルホスフェート、クレジルジフェニルホスフェート、トリクレジルホスフェート、トリキシレニルホスフェート、トリス(クロロエチル)ホスフェートなどのリン酸エステル系可塑剤;ジエチレングリコールジベンゾエート、ジプロピレングリコールジベンゾエート、トリエチレングリコールジベンゾエート、トリエチレングリコールジ−2−エチルブチレート、トリエチレングリコールジ−2−エチルヘキサノエート、ジブチルメチレンビスチオグリコレートなどのグリコール系可塑剤;グリセロールモノアセテート、グリセロールトリアセテート、グリセロールトリブチレートなどのグリセリン系可塑剤;エポキシ化大豆油、エポキシブチルステアレート、エポキシヘキサヒドロフタル酸ジ−2−エチルヘキシル、エポキシヘキサヒドロフタル酸ジイソデシル、エポキシトリグリセライド、エポキシ化オレイン酸オクチル、エポキシ化オレイン酸デシルなどのエポキシ系可塑剤;アジピン酸系ポリエステル、セバシン酸系ポリエステル、フタル酸系ポリエステルなどのポリエステル系可塑剤、あるいは部分水添ターフェニル、接着性可塑剤、さらにはジアリルフタレート、アクリル系モノマーやオリゴマーなどの重合性可塑剤などを挙げることができる。
【0015】
本発明方法により製造されたペースト加工用塩化ビニル系樹脂顆粒は、粉体流動性が良好で、空気による輸送やローリー輸送、自動計量など物流、加工工程の省人化に有効である。さらに、高温において効率的に噴霧乾燥することができ、なおかつペースト調製に際して可塑剤への分散性が良好であり、粗粒が少ないので、プラスチゾルを薄いコーティング用途に使用してもすじ引きや粒状凸起を起こしにくい。
【0016】
【実施例】
以下に、実施例を挙げて本発明をさらに詳細に説明するが、本発明はこれらの実施例によりなんら限定されるものではない。
なお、実施例において、測定及び評価は下記の方法により行った。
(1)重合体粒子の粒径分布および平均粒径の測定
レーザー回折粒度分布測定装置[BROOKHAVEN INSTRUMENT CORP.製、BI−DCP]を用い、1,200rpmで回転しているディスクにスピン液として15mlのイオン交換水を入れ、次いでバッファ液としてメタノール1mlを、続いて試料濃度1重量%水分散液0.25mlを注入し、測定時間2時間にて塩化ビニル系重合体水性分散液の粒子又は乾燥により得られた顆粒の累積粒径分布を測定し、50重量%に相当する粒径を平均粒径とした。
(2)嵩密度(ゆるめ)
(株)細川粉体工学研究所製パウダーテスターを使用して、JIS K 6721に準じて測定した。
(3)安息角
(株)細川粉体工学研究所製パウダーテスターを使用し、振動する目開き710μmの篩面上に試料を供給し、シュート下に積もった粉体の裾の角度を測定した。安息角の値が小さいほど、粉体流動性が良好であることを意味する。
(4)ペースト粘度
25℃、相対湿度60%の雰囲気で、ペースト加工用塩化ビニル樹脂顆粒100重量部及びジ−2−エチルヘキシルフタレート(DOP)60重量部を擂潰機にて混練し、得られたプラスチゾルを真空脱泡し、25℃にて1時間放置したのち、ブルックフィールド型粘度計[(株)トキメック製、BM型(E−B8M)]により、ローター番号3、回転数6rpmにて測定した。
(5)未分散粒子率(250メッシュ篩上量)
試料粉体100gとジ−2−エチルヘキシルフタレート60gと内径85mmの円筒容器に入れて、その平面中央に図1に示す、回転軸中心からの翼長aが35mm、水平方向の翼幅bが20mm、厚さcが0.7mmの花弁状の平板翼2を、径8mmの撹拌軸4の下端の固定環3(環の高さdが14mm、外径eが13mm)に十字状に4枚配列してなる撹拌翼1を、翼の下面が容器底面から5mmとなる位置に据え付けて、回転速度500rpmにて5分間撹拌混合して得られるプラスチゾルを、ミネラルスピリット100gで希釈してJIS62μm標準篩(呼称250メッシュ)でろ過し、メタノールで重量既知のシャーレ上に洗い落し、メタノールを揮散させてシャーレ上の樹脂の重量を求め、試料粉体100gに対する%値で表示する。上記%値が小さいほどゾル分散性が良いことを意味する。
(6)セーバーズ流出量
23℃、相対湿度60%の雰囲気で、ペースト加工用塩化ビニル系樹脂顆粒100重量部及びジ−2−エチルヘキシルフタレート60重量部を擂漬機にて混練して得られたプラスチゾルを真空脱泡し、23℃にて1時間放置したのち、セーバーズ流量計(カスター社製、Model A−100)を用い、長さ50mm、径1.56mmのノズルから、95psiの圧力下で流出させ、100秒間のゾル流出量(g)を測定する。流出量が多いほど、高剪断速度下でのゾル粘度が低いことを示す。
【0017】
製造例1(微細懸濁重合による塩化ビニル重合体水性分散液の製造)
ステンレス製の撹拌機及びジャケットを備えた耐圧反応器に、脱イオン水82重量部、ドテシルベンゼンスルホン酸ナトリウム2重量部、ラウリルアルコール1重量部及びラウロイルパーオキシド0.2重量部を仕込み、窒素加圧と窒素放出を2回繰り返したのち減圧脱気した。次いで、塩化ビニル100重量部を仕込み、30分激しく混合したのちホモジナイザーにかけて、同様に窒素置換後脱気したステンレス製の撹拌機及びジャケットを備えた別の反応器に移送し、ゆっくり撹拌しつつ、62℃にて重合反応を行った。反応器の圧力が5.5kg/cm2Gまで降下した時点で冷却し、未反応単量体を回収して塩化ビニル重合体水性分散液Aを得た。
塩化ビニル重合体水性分散液Aは、固形分濃度53.0重量%であり、1次粒子は粒径2.1μmの位置に頂点があり、0.2〜5.2μmの範囲に広く連続的に分布する山形の粒径分布を有していた。
製造例2(乳化重合による塩化ビニル重合体水性分散液の製造)
ステンレス製の撹拌機及びジャケットを備えた耐圧反応器に、脱イオン水167重量部、ステアリン酸0.2重量部、過硫酸カリウム0.02重量部及びラウリン酸ナトリウム0.01重量部を仕込み、窒素加圧と窒素放出を2回繰り返したのち減圧脱気した。次いで、塩化ビニル100重量部を仕込み、撹拌しながら昇温し、60℃にて重合反応を行った。重合転化率5〜85重量%の期間に、3重量%ラウリン酸ナトリウム水溶液16重量部を一定速度で添加し、反応器の圧力が5.0kg/cm2Gまで降下した時点で冷却し、5重量%ラウリン酸ナトリウム水溶液20重量部を添加し、未反応単量体を回収して塩化ビニル重合体水性分散液Bを得た。
塩化ビニル重合体水性分散液Bは、固形分濃度31.0重量%であり、1次粒子は粒径0.3μmの位置に頂点があり、0.1〜0.4μmの狭い範囲に粒径が分布していた。
【0018】
製造例3(塩化ビニル重合体水性分散液の濃縮)
塩化ビニル重合体水性分散液AをNaCl阻止率10%のナノフィルター膜で限外ろ過にかけ、固形分濃度60.5重量%の塩化ビニル重合体水性分散液A2を得た。
製造例4(塩化ビニル重合体水性分散液の混合及び濃縮)
塩化ビニル重合体水性分散液A80重量部と、塩化ビニル重合体水性分散液B20重量部とを混合して固形分濃度48.6重量%の塩化ビニル重合体水性分散液Cを得た。
さらに、塩化ビニル重合体水性分散液CをNaCl阻止率10%のナノフィルター膜で限外ろ過にかけ濃縮して、固形分濃度65.5重量%の塩化ビニル重合体水性分散液C2を得た。
製造例5(塩化ビニル重合体水性分散液の混合及び濃縮)
塩化ビニル重合体水性分散液A76重量部と塩化ビニル重合体水性分散液B24重量部とを混合して固形分濃度47.7重量%の塩化ビニル重合体水性分散液Dを得、これをNaCl阻止率10%のナノフィルター膜で限外ろ過にかけ濃縮して、固形分濃度69.5重量%の塩化ビニル重合体水性分散液D2を得た。
製造例6(塩化ビニル重合体水性分散液の混合及び濃縮)
塩化ビニル重合体水性分散液A42重量部と塩化ビニル重合体水性分散液B58重量部とを混合して固形分濃度40.3重量%の塩化ビニル重合体水性分散液Eを得、これをNaCl阻止率10%のナノフィルター膜で限外ろ過にかけ濃縮し、固形分濃度48.0重量%の塩化ビニル重合体水性分散液E2を得た。
製造例7(播種乳化重合による塩化ビニル重合体水性分散液の製造及び濃縮)
ステンレス製の撹拌機及びジャケットを備えた耐圧反応器に、脱イオン水105重量部、中心粒子径0.55μmの塩化ビニル重合体種子35重量%を含む水性分散液20重量部および過硫酸カリウム0.1重量部を仕込み、窒素加圧と窒素放出を2回繰り返したのち減圧脱気した。次いで、塩化ビニル100重量部を仕込み、撹拌しながら昇温し、55℃、反応器圧力8.0kg/cm2Gにて重合反応を開始した。重合転化率が5重量%になった時点から、ラウリル硫酸ナトリウム5重量%水溶液を添加開始し、重合転化率85重量%の時点まで合計8重量部を添加した。反応器圧力が4.5kg/cm2Gに低下した時点で、ラウリル硫酸ナトリウム25重量%水溶液0.6重量部を添加後冷却し、未反応単量体を回収して固形分濃度42.0重量%の塩化ビニル重合体水性分散液Fを得た。
塩化ビニル重合体水性分散液FをNaCl阻止率10%のナノフィルター膜で限外ろ過にかけ濃縮し、固形分濃度56重量%の塩化ビニル重合体水性分散液F2を得た。
実施例1
内径1,200mm、高さ800mmの円柱部と、その下の高さ780mmの円錐部とをチャンバーとし、その頂部内中央に直径12cm、回転数12,000rpmの回転円盤式アトマイザーを有する噴霧乾燥機を用い、乾燥用空気の入口温度167℃、乾燥用空気の出口温度55℃の条件で、塩化ビニル重合体水性分散液C2を噴霧乾燥した。
水性分散液の処理速度は32.3kg/hrであり、顆粒の平均粒径は50μm、嵩密度(ゆるめ)は0.54g/cm3、安息角は41度であった。また、ペースト粘度は1,640cpであり、未分散粒子率は0.054重量%、セーバーズ流出量は50g/100秒であった。
【0019】
実施例2
乾燥用空気の入口温度を90℃、乾燥用空気の出口温度50℃とした以外は、実施例1と同じ条件で噴霧乾燥を行った。
水性分散液の処理速度は10.0kg/hrであり、顆粒の平均粒径は41μm、嵩密度(ゆるめ)は0.52g/cm3、安息角は41度であった。また、ペースト粘度は1,660cpであり、未分散粒子率は0.034重量%、セーバーズ流出量は49g/100秒であった。
実施例3
塩化ビニル重合体水性分散液C2の代わりに、塩化ビニル重合体水性分散液D2を用いて、実施例1と同様に噴霧乾燥を行った。
水性分散液の処理速度は34.3kg/hrであり、顆粒の平均粒径は52μm、嵩密度(ゆるめ)は0.50g/cm3、安息角は41度であった。また、ペースト粘度は1,750cpであり、未分散粒子率は0.050重量%、セーバーズ流出量は52g/100秒であった。
比較例1
塩化ビニル重合体水性分散液C2の代わりに、塩化ビニル重合体水性分散液Cを用いて、実施例1と同様に噴霧乾燥を行った。
水性分散液の処理速度は29.0kg/hrであり、顆粒の平均粒径は32μm、嵩密度(ゆるめ)は0.43g/cm3、安息角は55度であった。また、ペースト粘度は1,640cpであり、未分散粒子率は0.408重量%、セーバーズ流出量は49g/100秒であった。
【0020】
比較例2
塩化ビニル重合体水性分散液C2の代わりに、塩化ビニル重合体水性分散液Aを用いて、実施例1と同様に噴霧乾燥を行った。
水性分散液の処理速度は29.1kg/hrであり、顆粒の平均粒径は34μm、嵩密度(ゆるめ)は0.42g/cm3、安息角は54度であった。また、ペースト粘度は2,100cpであり、未分散粒子率は0.342重量%、セーバーズ流出量は10g/100秒であった。
比較例3
塩化ビニル重合体水性分散液C2の代わりに、塩化ビニル重合体水性分散液E2を用いて、実施例1と同様に噴霧乾燥を行った。
水性分散液の処理速度は29.0kg/hrであり、顆粒の平均粒径は28μm、嵩密度(ゆるめ)は0.43g/cm3、安息角は53度であった。また、ペースト粘度は4,000cpであり、未分散粒子率は0.822重量%、セーバーズ流出量は12g/100秒であった。
比較例4
塩化ビニル重合体水性分散液C2の代わりに、塩化ビニル重合体水性分散液F2を用いて、実施例1と同様に噴霧乾燥を行った。
水性分散液の処理速度は30.0kg/hrであり、顆粒の平均粒径は34μm、嵩密度(ゆるめ)は0.42g/cm3、安息角は54度であった。また、ペースト粘度は4,300cpであり、未分散粒子率は0.313重量%、セーバーズ流出量は30g/100秒であった。
参考例1
塩化ビニル重合体水性分散液C2の代わりに、塩化ビニル重合体水性分散液Cを用いて、実施例2と同様に噴霧乾燥を行った。
水性分散液の処理速度は6.6kg/hrで乾燥の生産性が低かった。顆粒の平均粒径は22μm、嵩密度(ゆるめ)は0.43g/cm3、安息角は53度であった。また、ペースト粘度は1,620cpであり、未分散粒子率は0.034重量%、セーバーズ流出量は50g/100秒であった。
実施例1〜3の結果を第1表に、比較例1〜4及び参考例1の結果を第2表に示す。
【0021】
【表1】
【0022】
【表2】
【0023】
実施例1〜3の方法により得られた本発明の要件を備えたペースト加工用塩化ビニル系樹脂顆粒は、いずれも嵩密度0.5g/cm3以上、安息角41度の優れた粉体流動性を有し、またペーストの粘度も低く、かつ未分散粒子率が極めて小さい。
比較例1においては、実施例1と同じ粒径分布の重合体分散液ではあるが、固形分濃度が48.6重量%と低いため、これを乾燥して得られた樹脂顆粒は、粉体流動性、ゾル分散性共に悪いものであった。
比較例2においては、重合体粒子の小さい粒子径に極大が無く、比較例3においては、重合体粒子の大小粒子の比率が不適で、また、比較例4においては、重合体粒子径に0.2〜5μmの範囲で分布の断続があり、得られた樹脂顆粒はいずれも粉体流動性およびゾル分散性の劣るものであった。
参考例1は、乾燥温度条件を入口90℃、出口50℃と低温にしたほかは、比較例1と同様に行った生産性の極めて低いケースであり、未分散粒子率は小さく、低粘度のペーストを与える樹脂顆粒が得られた。
【0024】
【発明の効果】
本発明によれば、粒径範囲と粒径分布を規定した塩化ビニル系重合体を特定の濃度で含有する水性分散液を、好ましくは100℃より高い温度の乾燥用加熱空気を用いて噴霧乾燥処理することにより、粉体流動性に優れ、かつペースト調製に際して可塑剤への分散性の良好なペースト加工用塩化ビニル系樹脂顆粒を効率よく製造することができる。
【図面の簡単な説明】
【図1】図1は、実施例及び比較例において、塩化ビニル樹脂顆粒の未分散粒子率を測定するための撹拌装置の詳細図であって、(A)は側面図、(B)は平面図である。
【符号の説明】
1 撹拌翼
2 花弁状平板翼
3 固定環
4 撹拌軸[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vinyl chloride resin granule for paste processing and a method for producing the same. More specifically, the present invention relates to a vinyl chloride resin granule for paste processing having excellent powder flowability and good dispersibility in a plasticizer during paste preparation, and a method for producing the same.
[0002]
[Prior art]
Automatic measurement of vinyl chloride resin powder for paste processing, which was difficult in the past, while preventing deterioration of the work environment due to dust generation when opening the bag packing the vinyl chloride resin for paste processing In order to enable supply, an aqueous dispersion of a vinyl chloride polymer having a primary particle size of about 0.1 to 5 μm obtained by emulsion polymerization or fine suspension polymerization is spray-dried and granulated to obtain an average particle size. A method of making vinyl chloride resin granules having a diameter of about 50 to 250 μm is known.
This vinyl chloride resin granule is used without being pulverized as it is during paste processing. That is, the vinyl chloride resin granule for paste processing is mixed with a plasticizer and other compounding agents such as a heat stabilizer and a filler as necessary to form a plastisol.
Various proposals have been made as methods for producing this vinyl chloride resin granule for paste processing. For example, in Japanese Patent Application Laid-Open No. 2-133410, in a spray drying, an operation is performed at an inlet air temperature of 100 ° C. or less and an outlet air temperature of 50 ° C. or less, and the total mass is obtained as a vinyl chloride resin granule having good powder characteristics and a large bulk specific gravity. Spherical vinyl chloride resin granules are proposed in which the proportion of spherical granules having a diameter of 20 μm or more is 60% by weight or more.
Japanese Patent Application Laid-Open No. 2-225529 discloses an absolute humidity of 0.007 to 0.014 kg water / as a method for producing a vinyl chloride resin for processing a particulate paste with good flowability, less fine powder and less dust generation. There has been proposed a method of obtaining particulate resin by using air of kg air and setting the drying air inlet temperature to 100 ° C. or lower and the drying air outlet temperature to 53 ° C. or lower. However, these production methods are all low in productivity because they are dried at a low temperature, and have problems such as an increase in the size of a dryer and an increase in energy costs in order to ensure a long spray dwell time. are doing.
[0003]
[Problems to be solved by the invention]
Under such circumstances, the present invention is a method for efficiently producing a vinyl chloride resin granule for paste processing having excellent powder flowability and good dispersibility in a plasticizer during paste preparation, and this The object of the present invention is to provide a vinyl chloride resin granule for paste processing having the above properties obtained by a method.
[0004]
[Means for Solving the Problems]
As a result of intensive studies on a method for producing a vinyl chloride resin granule for paste processing having the above-mentioned preferred properties, the present inventors have determined that a vinyl chloride polymer having a specific particle size range and particle size distribution is a predetermined one. It has been found that the object can be achieved by spray-drying the aqueous dispersion containing the concentration, preferably using heating air for drying at a temperature higher than 100 ° C., and the present invention has been completed based on this finding. It came to do.
That is, the present invention
(1) The particle size of polymer particles measured by laser diffraction method is continuously distributed in a range of at least 0.2 to 5 μm, has two maximum values in frequency, and the maximum value of a group of small particles. The particle size given is in the range of 0.2 to 0.6 μm, the particle size giving the maximum value of the group of large particles is in the range of 1.0 to 4.0 μm, and the average particle size of the whole is 0.6 to The particle size distribution is 3.0 μm, and the ratio of the particles having a particle size of 0.1 to 0.7 μm and the particles having a particle size of 0.8 to 5 μm is 5 to 40% by weight to 60 to 95% by weight. The paste obtained by mixing 100 parts by weight of the resin and 60 parts by weight of di-2-ethylhexyl phthalate has an undispersed particle ratio of 0.1% by weight or less and a Savers outflow of 30 g / 100 seconds or more. Vinyl chloride resin granules for paste processing,
(2) The particle size of the polymer particles measured by the laser diffraction method is continuously distributed in a range of at least 0.2 to 5 μm, has two maximum values in frequency, and the maximum value of a group of small particles. The particle size given is in the range of 0.2 to 0.6 μm, the particle size giving the maximum value of the group of large particles is in the range of 1.0 to 4.0 μm, and the average particle size of the whole is 0.6 to The particle size distribution is 3.0 μm, and the ratio of the particles having a particle size of 0.1 to 0.7 μm and the particles having a particle size of 0.8 to 5 μm is 5 to 40% by weight to 60 to 95% by weight. A method for producing a vinyl chloride resin granule for paste processing, characterized by spray-drying an aqueous dispersion containing 55 to 75% by weight of a vinyl chloride polymer; and
(3) A method for producing a vinyl chloride resin granule for paste processing according to (2), wherein heating air for drying at a temperature higher than 100 ° C. is used for the spray drying treatment,
Is to provide.
Furthermore, as a preferred embodiment of the present invention,
(4) Item (2), wherein the aqueous dispersion of the vinyl chloride polymer to be subjected to the spray drying treatment is a mixture of an aqueous dispersion obtained by fine suspension polymerization and an aqueous dispersion obtained by emulsion polymerization. Or a method for producing a vinyl chloride resin granule for paste processing according to item (3),
Can be mentioned.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The method for producing vinyl chloride resin granules for paste processing of the present invention is a method of spray-drying an aqueous dispersion of a vinyl chloride polymer, and the aqueous dispersion of the vinyl chloride polymer includes the following: It is necessary to use one containing a vinyl chloride polymer having a particle size and a particle size distribution.
First, in the vinyl chloride polymer, the particle size of polymer particles measured by laser diffraction method is continuously distributed in a range of at least 0.2 to 5 μm, and has two maximum values in frequency, The particle size giving the maximum value of the group of particles needs to be in the range of 0.2 to 0.6 μm, and the particle size giving the maximum value of the group of particles should be in the range of 1.0 to 4.0 μm. is there. Next, the average particle size of the whole is 0.6 to 3.0 μm, preferably 1.0 to 2.5 μm, and particles having a particle size of 0.1 to 0.7 μm and particles having a particle size of 0.8 to 5 μm. It is necessary to have a particle size distribution in which the ratio is 5 to 40% by weight to 60 to 95% by weight, preferably 15 to 30% by weight to 70 to 85% by weight. Here, the total of the ratio of particles having a particle diameter of 0.1 to 0.7 μm and the ratio of particles having a particle diameter of 0.8 to 5 μm is 100% by weight. When the particle size distribution and the average particle size deviate from the ranges specified above, vinyl chloride resin granules having desired properties cannot be obtained. The method for measuring the particle size distribution and the average particle size by the laser diffraction method in the present invention will be described later.
Furthermore, the aqueous dispersion of the vinyl chloride polymer used in the present invention needs to contain the vinyl chloride polymer having the above properties at a concentration of 55 to 75% by weight. If the content of the vinyl chloride polymer deviates from the above range, vinyl chloride resin granules having desired properties cannot be obtained.
The vinyl chloride resin granule for paste processing produced by the method of the present invention is a spherical aggregate of polymer particles formed by removing water from spray droplets by drying. Here, the spherical shape is not limited to a true spherical shape, and includes a spheroid having a major axis: minor axis ratio of about 1: 1 to 1: 0.8 and a spheroid that is deformed to some extent. By using spherical polymer particles, the fluidity of the granules can be improved.
[0006]
As a method for preparing an aqueous dispersion of a vinyl chloride polymer used in the method of the present invention, an aqueous dispersion containing a vinyl chloride polymer having a particle size distribution and a particle size at a predetermined concentration can be obtained. There is no particular limitation, but for example, the following method is preferably used. That is, vinyl chloride alone or a mixture of co-monomers mainly composed of vinyl chloride and copolymerizable therewith is subjected to fine suspension polymerization, and the resulting vinyl chloride polymer aqueous dispersion is the same as described above. By mixing an aqueous dispersion of a vinyl chloride polymer obtained by emulsion polymerization of monomers, a desired aqueous dispersion of a vinyl chloride polymer can be efficiently prepared.
The emulsion polymerization includes seeding emulsion polymerization, and the fine suspension polymerization includes seeding fine suspension polymerization.
In the method of the present invention, the amount of vinyl chloride in the mixture is preferably 50% by weight or more, and preferably 75% by weight or more in the mixture of vinyl chloride as a main component and a comonomer that can be copolymerized therewith. Is more preferable. Examples of comonomers that can be copolymerized with vinyl chloride include olefinic compounds such as ethylene and propylene; vinyl esters such as vinyl acetate and vinyl propionate; unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid; acrylics Unsaturated monocarboxylic esters such as methyl acrylate, ethyl acrylate, acrylic acid-n-butyl, acrylic acid-2-hydroxyethyl, methyl methacrylate, ethyl methacrylate, methacrylic acid-N, N-dimethylaminoethyl; acrylamide , Unsaturated amides such as methacrylamide; unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated dicarboxylic acids such as maleic acid and fumaric acid; esters and anhydrides thereof; N-substituted maleimides; vinyl methyl ether , Vinyl ethyl ether And vinyl ethers such as vinyl; and vinylidene compounds such as vinylidene chloride.
[0007]
When fine suspension polymerization is performed on vinyl chloride alone or a mixture of vinyl chloride as a main component and a copolymerizable monomer, first, vinyl chloride alone or vinyl chloride as a main component is copolymerized in an aqueous medium. Premixed with a mixture of comonomer that can be added, oil-soluble polymerization initiator, emulsifier, if necessary, higher alcohol, higher fatty acid and its ester, dispersing aid such as chlorinated paraffin, and other additives. The particle size of the oil droplets is adjusted by homogenization with a homogenizer. As the homogenizer, for example, a colloid mill, a vibration stirrer, a two-stage high-pressure pump, or the like can be used. The homogenized liquid is sent to the polymerization vessel, the temperature in the polymerization vessel is raised while gently stirring to start the polymerization reaction, and then the polymerization can be carried out until a predetermined conversion rate is reached. The polymerization temperature is preferably 30 to 80 ° C. In seeding fine suspension polymerization, pure water and seed polymer in which the polymerization initiator remains in the particles are charged into the polymerization vessel, and deaeration in the polymerization vessel or replacement with an inert gas such as nitrogen as necessary. Thereafter, the polymerization can be advanced by charging vinyl chloride alone or a mixture of vinyl chloride as a main component and a comonomer that can be copolymerized therewith, and gradually raising the temperature in the polymerization vessel while stirring gently. The polymerization temperature is preferably 30 to 80 ° C. In the case of seeding fine suspension polymerization, a polymerization initiator may not be newly added.
[0008]
Examples of oil-soluble polymerization initiators used for fine suspension polymerization include diacyl peroxides such as acetyl peroxide, 3,5,5-trimethylhexanoyl peroxide, lauroyl peroxide, benzoyl peroxide, and naphthoyl peroxide. Ketone ketones such as methyl ethyl ketone peroxide; peroxyesters such as t-butyl peroxypivalate, tetramethylbutyl neodecanate, cumyl peroxyneodecanate; diisopropyl peroxydicarbonate, diethylhexylperoxydicarbonate, etc. Peroxydicarbonates; organic peroxides such as sulfonyl peroxides such as acetylcyclohexylsulfonyl peroxide; 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutoxide And azo compounds such as 2,2'-azobis (2,4-dimethylvaleronitrile) and 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile). Moreover, as an emulsifier to be used, an anionic surfactant or a nonionic surfactant is mentioned. Examples of the anionic surfactant include alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate; alkyl sulfates such as sodium lauryl sulfate and sodium tetradecyl sulfate; sodium dioctyl sulfosuccinate and sodium dihexyl sulfosuccinate. Sulfosuccinates; fatty acid salts such as sodium laurate and semi-cured tallow fatty acid potassium; ethoxy sulfate salts such as polyoxyethylene lauryl ether sulfate sodium salt and polyoxyethylene nonylphenyl ether sulfate sodium salt; alkane sulfonates; alkyl ethers A phosphoric acid ester sodium salt etc. can be mentioned. Examples of nonionic surfactants include polyoxyethylene nonyl phenyl ether and polyoxyethylene sorbitan lauryl ester. The amount of the emulsifier used varies depending on the polymerization method to be applied, but it is usually preferably 0.2 to 2.5 parts by weight per 100 parts by weight of the monomer.
[0009]
By this fine suspension polymerization, an aqueous dispersion of a vinyl chloride polymer of spherical polymer particles in which the primary particle diameter is continuously distributed over a wide range of about 0.05 to 5 μm and has a mountain-shaped frequency distribution. Can be obtained. Further, by the seeding fine suspension polymerization, the vinyl chloride polymer of the spherical polymer particles having a particle size distribution having a mountain-shaped distribution continuously in a wide range where the particle size of the primary particles is about 0.3 to 10 μm. An aqueous dispersion can be obtained. Here, in the present invention, the particle size distribution and average particle size of the vinyl chloride polymer are measured by a laser diffraction method.
On the other hand, when emulsion polymerization is performed on vinyl chloride alone or a mixture of vinyl chloride as a main component and a comonomer that can be copolymerized therewith, the polymerizer is charged with pure water, an emulsifier, a water-soluble polymerization initiator, and the like. Degassing inside or substituting with an inert gas such as nitrogen as necessary, charging vinyl chloride alone or a mixture of vinyl chloride as a main component and a comonomer that can be copolymerized with this, and stirring to a single amount While forming the emulsifier micelle layer solubilized by the body, the polymerization is carried out by raising the temperature in the polymerization vessel. In order to control the reaction rate and particle size, an emulsifier, an initiator, a reducing agent and the like can be added during the polymerization reaction. The polymerization temperature is preferably in the range of 30 to 80 ° C.
By this emulsion polymerization, an aqueous dispersion of a polymer having a narrow particle size distribution in a single mode having an average particle size of about 0.2 to 0.7 μm and a distribution range of an average particle size ± 0.2 to 0.4 μm. Obtain a liquid.
In the seeding emulsion polymerization method, an anionic surfactant is used to stabilize the polymer particles by using the polymer obtained by emulsion polymerization as a seed and enlarging it in an aqueous medium by polymerizing monomers. The resulting emulsifier is polymerized using a water-soluble polymerization initiator while being added in accordance with the progress of the polymerization reaction so as not to exceed the amount necessary to cover the surface of the polymer particles. The polymerization temperature is preferably in the range of 30 to 80 ° C. By this sowing emulsion polymerization, the seeds are enlarged with an average particle size of about 0.9 to 2.0 μm and a distribution range of one sharp particle size frequency distribution with an average particle size of ± 0.3 to 0.5 μm. Large particles are produced. In addition to the large particles, by-product small particles having an average particle size of about 0.2 to 0.4 μm are often included in a proportion of 20% by weight or less, and the particles often have a bimodal particle size distribution.
[0010]
Examples of the emulsifier used include those similar to those used for the fine suspension polymerization. Examples of the water-soluble polymerization initiator used include water-soluble peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide, these peroxides or cumene hydroperoxide, t-butyl hydroperoxide, and the like. Redox initiator, 2,2'-azobis (2,2'-azobis), which is a combination of hydroperoxide and a reducing agent such as acidic sodium sulfite, ammonium sulfite, ascorbic acid, ferric ion sodium ethylenediaminetetraacetate complex, ferrous pyrophosphate And water-soluble azo compounds such as 2-methylpropionamidine) dihydrochloride.
The solid content concentration of the aqueous dispersion of the vinyl chloride polymer obtained by emulsion polymerization, seeding emulsion polymerization, fine suspension polymerization or seeding fine suspension polymerization is usually about 35 to 55% by weight. Such an aqueous dispersion can be concentrated to about 40 to 65% by weight by ultrafiltration or evaporation, but if concentrated to 60% by weight or more, the fluidity of the aqueous dispersion is likely to change. An aqueous dispersion having a concentration of less than% by weight was subjected to a spray drying process. However, in the method of the present invention, the specific particle size distribution according to the present invention is given to the vinyl chloride polymer, so that the polymer particles can be packed more densely, or the upper limit of the concentration that can be concentrated is raised. Can do. For example, an aqueous dispersion containing polymer particles having a broad chevron particle size distribution of about 0.05 to 5 μm obtained by fine suspension polymerization, or a particle size obtained by seeding fine suspension polymerization An aqueous dispersion containing polymer particles having a broad chevron particle size distribution of about 0.3 to 10 μm, and a weight having a narrow particle size distribution of about 0.2 to 0.3 μm obtained by emulsion polymerization. An aqueous dispersion of a polymer having a specific particle size distribution according to the present invention is mixed with an aqueous dispersion containing coalesced particles at a weight ratio of the polymer of 60:40 to 90:10. A liquid can be obtained. Also, in the case of fine suspension polymerization, the particle size is continuously distributed from 0.2 to about 10 μm by a method of homogenizing by dispersing the dispersion aid or polymerization initiator in the form of emulsion with monomers and water. In addition, it is possible to obtain an aqueous dispersion of a polymer having a specific particle size distribution according to the present invention having modes at a position of about 0.2 to 0.4 μm and a position of about 0.5 to 3 μm. . Alternatively, as disclosed in JP-A-10-87707, a polymer dispersion by emulsion polymerization is mixed with a polymer aqueous dispersion by fine suspension polymerization at a polymer weight ratio of 0.5 to 2. The polymer having a specific particle size distribution according to the present invention can also be prepared by subjecting the resulting product to enlargement polymerization as a seed. With such a polymer having a specific particle size distribution, a polymer aqueous dispersion that is fluid even if the solid content concentration is concentrated to 55 to 75% by weight, preferably 60 to 70% by weight is prepared. be able to.
[0011]
Examples of the concentration method of the aqueous dispersion of the vinyl chloride polymer include concentration using a dialysis membrane or an ultrafiltration membrane, concentration using a vacuum evaporator, and concentration using a thin film evaporator. Among these, the membrane used for membrane concentration is not particularly limited, and examples thereof include a cellulose acetate membrane, a polysulfone membrane, a polyamide membrane, a polyacrylonitrile membrane, and a fluororesin membrane.
In the method of the present invention, an aqueous dispersion of a vinyl chloride polymer having a specific particle size distribution of the vinyl chloride polymer having a solid content concentration of 55 to 75% by weight, preferably 60 to 70% by weight is sprayed. Dry. There is no particular limitation on the spray dryer to be used. For example, examples of the spray type include a rotary disk atomizer, a two-fluid nozzle atomizer, and a pressure nozzle atomizer. Among these, a rotary disk atomizer is included. Can be suitably used because it can widely cope with fluctuations in the flow rate, density, viscosity and the like of the aqueous dispersion. There is no particular limitation on the contact method between the hot air and the droplet group, but the combined flow method is preferable for reducing the thermal history distribution of the resin granules. The drying air can be collected from the atmosphere, and it is not necessary to adjust the humidity. However, humidity adjustment is not limited. The higher the inlet temperature of the drying air, the higher the drying efficiency can be expected. However, when the temperature exceeds 200 ° C., the sol dispersibility of the resin granules deteriorates. However, a low temperature of 100 ° C. or lower as in the prior art is not essential, and may be higher than 100 ° C. and 200 ° C. or lower, and a range of 110 to 170 ° C. is particularly preferable. Moreover, the range of 40-70 degreeC is preferable and, as for the exit temperature of drying air, the range of 45-55 degreeC is more preferable. The degree of drying is preferably 0.05 to 1.5% by weight, more preferably 0.1 to 1.0% by weight, of water contained in the dried granule. The outlet temperature of the drying air and the moisture content of the dried granules can be adjusted by controlling the supply rate of the aqueous dispersion of the vinyl chloride polymer and the temperature and air volume of the drying hot air. The spray droplet diameter depends on the supply rate and solid content of the aqueous dispersion of the vinyl chloride polymer, the rotational speed of the disk for the rotary disk type atomizer, the atomizing air pressure and the air volume for the two-fluid nozzle type atomizer, and the pressurized nozzle type. In the atomizer, pressure can be controlled as a main factor. By spray-drying an aqueous dispersion of a vinyl chloride polymer, granules having an average particle diameter of 20 to 150 μm can be usually obtained.
[0012]
In the method of the present invention, high temperature drying air can be used by spray-drying an aqueous dispersion of a vinyl chloride polymer having a solid concentration of 55 to 75% by weight, preferably 60 to 70% by weight. In addition, it is possible to obtain vinyl chloride resin granules having excellent powder fluidity and good dispersibility in a plasticizer during paste preparation. The reason why the vinyl chloride resin granules for paste processing produced by the method of the present invention have good dispersibility in the plasticizer is not clear, but is presumed to be due to the following mechanism. That is, when water is evaporated from the droplets of the aqueous dispersion sprayed in the spray dryer in the course of drying, when the water moves from the inside of the droplets to the surface of the droplets, the solid content concentration of the aqueous dispersion is When it is low, fine particles having a particle size of about 0.05 to 0.2 μm are arranged on the surface of the droplets along the movement of water. Resin granules whose surfaces are covered with fine particles form a firm surface by heating during drying, and therefore are difficult to loosen when the resin granules are mixed with a plasticizer. On the other hand, the vinyl chloride resin granules for paste processing produced by the method of the present invention have a high solid content concentration of the aqueous dispersion subjected to spray drying, so that the water inside the droplet moves to the droplet surface. There is no longer a flow enough to entrain fine particles. Therefore, since the arrangement of fine particles is unlikely to exist on the surface of the resin granule, the granule surface is not firm, and the granule is easily dispersed in the plasticizer, and the undispersed particle ratio indicating the measurement method in the examples described later is 0. 0.1 wt% or less, preferably 0.02 to 0.08 wt%.
On the surface of the vinyl chloride resin granules for paste processing obtained by the method of the present invention, it is difficult to form a fine particle layer that is firmly fused by heat, so that the temperature of the spray drying air inlet is higher than 100 ° C. Even operations that increase productivity tend to loosen up against plasticizers.
Resin granules obtained by this spray-drying process are not easily loosened by plasticizers for use in paste processing, such as large spherical aggregate particles or fragments formed by peeling off the powder layer attached to the inner wall of the dryer. Coarse grains may be included. In the method for producing a vinyl chloride resin granule for paste processing of the present invention, it is preferable to classify in order to remove these coarse particles following the spray drying treatment. In the method of the present invention, the type of the classification step is not particularly limited, but a vibrating sieve, particularly an ultrasonic vibrating sieve can be preferably used so as not to break the granules.
In addition, the vinyl chloride resin granules for paste processing of the present invention are more likely to have a fine particle layer on the surface, or even when manufactured without using low-temperature drying, but the surface is less likely to be polished. Therefore, good powder flowability immediately after drying is maintained for a long time. Bulk density is 0.48 ~ 0.60g / cm Three , Preferably 0.50 to 0.58 g / cm Three The angle of repose is 36 to 46 degrees, preferably 39 to 45 degrees.
[0013]
The present invention also provides a vinyl chloride resin granule obtained by the above-described production method, wherein a paste containing 100 parts by weight of the vinyl chloride resin granule and 60 parts by weight of di-2-ethylhexyl phthalate has a Savers outflow amount of 30 g. The present invention also provides a vinyl chloride resin for paste processing that is at least / 100 seconds, preferably at least 40 g / 100 seconds.
The greater the Savers runoff, the lower the sol viscosity at high shear rates. In addition, the measuring method of the saver outflow amount of the said paste is shown later.
There is no particular limitation on the method of preparing plastisol using the vinyl chloride resin granules for paste processing obtained by the method of the present invention, and it is possible to adopt a known method conventionally used in the preparation of vinyl chloride resin plastisol. it can. For example, plasticizer and various additive components used as required for vinyl chloride resin granules for paste processing, such as heat stabilizers, fillers, foaming agents, foaming accelerators, surfactants, viscosity modifiers, adhesiveness Addition agent, coloring agent, diluent, UV absorber, antioxidant, reinforcing agent, other resin, etc. are blended, and enough to be homogeneous using planetary mixer, kneader, roll, crusher, etc. A plastisol can be prepared by kneading into the above.
[0014]
There is no restriction | limiting in particular in the plasticizer used for preparation of plastisol, What is conventionally used as a plasticizer of vinyl chloride-type resin plastisol can be used. Examples of such plasticizers include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, di-n-octyl phthalate, dinonyl phthalate, diisodecyl phthalate, diundecyl phthalate. Phthalate plasticizers such as ditridecyl phthalate, dicyclohexyl phthalate, butyl benzyl phthalate, diphenyl phthalate and dibenzyl phthalate; isophthalic acid esters such as dimethyl isophthalate, di-2-ethylhexyl isophthalate and diisooctyl isophthalate Plasticizer; di-2-ethylhexyl tetrahydrophthalate, di-n-octyl tetrahydrophthalate, diisodecyl tetrahydrophthalate Tetrahydrophthalate plasticizers such as di-n-butyl adipate, di-2-ethylhexyl adipate, diisononyl adipate, diisodecyl adipate and the like; di-n-hexyl azelate, di-2- Azelaic acid ester plasticizers such as ethylhexyl azelate and diisooctyl azelate; Sebacic acid ester plasticizers such as di-n-butyl sebacate and di-2-ethylhexyl sebacate; di-n-butyl maleate and dimethyl maleate Maleate ester plasticizers such as diate, diethyl maleate and di-2-ethylhexyl maleate; fumarate plasticizers such as di-n-butyl fumarate and di-2-ethylhexyl fumarate; tri-n- Hexyl trimellitate, Tri-2- Trimellitic ester plasticizers such as tilhexyl trimellitate, tri-n-octyl trimellitate, triisooctyl trimellitate, triisononyl trimellitate, triisodecyl trimellitate; tetra-2-ethylhexyl pyro Pyromellitic ester plasticizers such as melitrate and tetra-n-octylpyromellitate; citric acids such as triethyl citrate, tri-n-butyl citrate, acetyl triethyl citrate, acetyl tri-2-ethylhexyl citrate Ester plasticizers; Itaconic acid ester plasticizers such as monomethyl itaconate, monobutyl itaconate, dimethyl itaconate, diethyl itaconate, dibutyl itaconate, di-2-ethylhexyl taconate; butyl oleate, glycerin Oleic acid ester plasticizers such as rumonooleate and diethylene glycol monooleate; ricinoleic acid ester plasticizers such as methyl acetyl ricinoleate, butyl acetyl ricinolate, glyceryl mono ricinolate and diethylene glycol mono ricinolate; n-butyl stearate , Stearic acid ester plasticizers such as glycerin monostearate and diethylene glycol distearate; other fatty acid ester plasticizers such as diethylene glycol monolaurate, diethylene glycol dipelargonate and various fatty acid esters of pentaerythritol; triethyl phosphate, tributyl phosphate , Tri-2-ethylhexyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, credit Phosphate ester plasticizers such as diphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, tris (chloroethyl) phosphate; diethylene glycol dibenzoate, dipropylene glycol dibenzoate, triethylene glycol dibenzoate, triethylene glycol di-2- Glycol plasticizers such as ethyl butyrate, triethylene glycol di-2-ethylhexanoate, and dibutylmethylene bisthioglycolate; Glycerin plasticizers such as glycerol monoacetate, glycerol triacetate, and glycerol tributyrate; Bean oil, epoxy butyl stearate, di-2-ethylhexyl epoxy hexahydrophthalate, diisodecyl epoxy hexahydrophthalate, epoxy Epoxy plasticizers such as xytriglyceride, epoxidized octyl oleate, and epoxidized decyl oleate; polyester plasticizers such as adipic acid polyester, sebacic acid polyester, phthalic polyester, or partially hydrogenated terphenyl, adhesive And polymerizable plasticizers such as diallyl phthalate, acrylic monomers and oligomers.
[0015]
The vinyl chloride resin granule for paste processing produced by the method of the present invention has good powder flowability and is effective for labor saving of logistics and processing processes such as air transportation, lorry transportation, and automatic weighing. In addition, it can be efficiently spray-dried at high temperatures, has good dispersibility in plasticizers when preparing pastes, and has few coarse grains. Hard to get up.
[0016]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
In the examples, measurement and evaluation were performed by the following methods.
(1) Measurement of particle size distribution and average particle size of polymer particles
Using a laser diffraction particle size distribution measuring apparatus [BROOKHAVEN INSTRUMENT CORP., BI-DCP], 15 ml of ion-exchanged water is added as a spin liquid to a disk rotating at 1,200 rpm, and then 1 ml of methanol is used as a buffer liquid. Then, 0.25 ml of a 1% by weight aqueous dispersion of the sample concentration was injected, and the cumulative particle size distribution of the particles of the vinyl chloride polymer aqueous dispersion or the granules obtained by drying was measured at a measurement time of 2 hours. The particle diameter corresponding to% was defined as the average particle diameter.
(2) Bulk density (loose)
Measurement was performed according to JIS K 6721 using a powder tester manufactured by Hosokawa Institute of Powder Technology.
(3) Angle of repose
Using a powder tester manufactured by Hosokawa Powder Engineering Laboratory Co., Ltd., a sample was supplied on a vibrating sieve screen having a mesh opening of 710 μm, and the hem angle of the powder accumulated under the chute was measured. The smaller the angle of repose, the better the powder flowability.
(4) Paste viscosity
In an atmosphere of 25 ° C. and a relative humidity of 60%, 100 parts by weight of vinyl chloride resin granules for paste processing and 60 parts by weight of di-2-ethylhexyl phthalate (DOP) were kneaded with a crusher, and the resulting plastisol was vacuum degassed. After foaming and allowing to stand at 25 ° C. for 1 hour, measurement was performed with a Brookfield viscometer [manufactured by Tokimec, BM type (E-B8M)] at a rotor number of 3 and a rotational speed of 6 rpm.
(5) Undispersed particle ratio (250 mesh sieve amount)
Sample powder 100g, di-2-ethylhexyl phthalate 60g, and inside diameter 85mm cylindrical container, the blade length a from the center of the rotation axis shown in Fig. 1 is 35mm, and the blade width b in the horizontal direction is 20mm. 4 pieces of petal-like
(6) Savers outflow
The plastisol obtained by kneading 100 parts by weight of vinyl chloride resin granules for paste processing and 60 parts by weight of di-2-ethylhexyl phthalate in a pickling machine in an atmosphere of 23 ° C. and 60% relative humidity is vacuum degassed. The sample was allowed to stand at 23 ° C. for 1 hour, and then was allowed to flow out from a nozzle having a length of 50 mm and a diameter of 1.56 mm under a pressure of 95 psi using a Savers flow meter (manufactured by Custer, Model A-100) for 100 seconds. Measure sol efflux (g). The larger the amount of effluent, the lower the sol viscosity at high shear rate.
[0017]
Production Example 1 (Production of vinyl chloride polymer aqueous dispersion by fine suspension polymerization)
A pressure resistant reactor equipped with a stainless steel stirrer and jacket was charged with 82 parts by weight of deionized water, 2 parts by weight of sodium dodecylbenzenesulfonate, 1 part by weight of lauryl alcohol and 0.2 part by weight of lauroyl peroxide, and nitrogen. After repeating pressurization and nitrogen release twice, vacuum deaeration was performed. Next, 100 parts by weight of vinyl chloride was charged, mixed vigorously for 30 minutes, then passed through a homogenizer, transferred to another reactor equipped with a stainless steel stirrer and jacket that was similarly degassed after nitrogen substitution, and slowly stirred, The polymerization reaction was performed at 62 ° C. The reactor pressure is 5.5 kg / cm 2 When the temperature dropped to G, the system was cooled, and unreacted monomers were recovered to obtain a vinyl chloride polymer aqueous dispersion A.
The vinyl chloride polymer aqueous dispersion A has a solid content concentration of 53.0% by weight, and the primary particles have a peak at a particle size of 2.1 μm and are wide and continuous in the range of 0.2 to 5.2 μm. It had a chevron-shaped particle size distribution.
Production Example 2 (Production of aqueous dispersion of vinyl chloride polymer by emulsion polymerization)
A pressure resistant reactor equipped with a stainless steel stirrer and jacket was charged with 167 parts by weight of deionized water, 0.2 part by weight of stearic acid, 0.02 part by weight of potassium persulfate and 0.01 part by weight of sodium laurate, Nitrogen pressurization and nitrogen release were repeated twice, followed by degassing under reduced pressure. Next, 100 parts by weight of vinyl chloride was charged, the temperature was increased while stirring, and a polymerization reaction was performed at 60 ° C. During a period of 5 to 85% by weight of polymerization conversion, 16 parts by weight of 3% by weight aqueous sodium laurate solution was added at a constant rate, and the reactor pressure was 5.0 kg / cm. 2 When the temperature dropped to G, the mixture was cooled, 20 parts by weight of a 5% by weight aqueous sodium laurate solution was added, and unreacted monomers were recovered to obtain an aqueous vinyl chloride polymer dispersion B.
The vinyl chloride polymer aqueous dispersion B has a solid content concentration of 31.0% by weight, and the primary particles have a peak at a position of 0.3 μm in particle size, and a particle size in a narrow range of 0.1 to 0.4 μm. Was distributed.
[0018]
Production Example 3 (Concentration of vinyl chloride polymer aqueous dispersion)
The aqueous dispersion of vinyl chloride polymer A was subjected to ultrafiltration with a nanofilter membrane having a NaCl rejection of 10% to obtain an aqueous dispersion of vinyl chloride polymer A2 having a solid content concentration of 60.5% by weight.
Production Example 4 (Mixing and Concentration of Vinyl Chloride Polymer Aqueous Dispersion)
80 parts by weight of an aqueous vinyl chloride polymer dispersion A and 20 parts by weight of an aqueous vinyl chloride polymer dispersion B were mixed to obtain an aqueous vinyl chloride polymer dispersion C having a solid concentration of 48.6% by weight.
Further, the aqueous vinyl chloride polymer dispersion C was subjected to ultrafiltration with a nanofilter membrane having a NaCl rejection of 10% and concentrated to obtain an aqueous vinyl chloride polymer dispersion C2 having a solid content concentration of 65.5% by weight.
Production Example 5 (mixing and concentration of vinyl chloride polymer aqueous dispersion)
76 parts by weight of vinyl chloride polymer aqueous dispersion A and 24 parts by weight of vinyl chloride polymer aqueous dispersion B were mixed to obtain a vinyl chloride polymer aqueous dispersion D having a solid concentration of 47.7% by weight, which was blocked by NaCl. The solution was subjected to ultrafiltration with a nanofilter membrane having a rate of 10%, and concentrated to obtain a vinyl chloride polymer aqueous dispersion D2 having a solid content concentration of 69.5% by weight.
Production Example 6 (mixing and concentration of vinyl chloride polymer aqueous dispersion)
42 parts by weight of vinyl chloride polymer aqueous dispersion A and 58 parts by weight of vinyl chloride polymer aqueous dispersion B were mixed to obtain a vinyl chloride polymer aqueous dispersion E having a solid concentration of 40.3% by weight, which was blocked by NaCl. The resultant was subjected to ultrafiltration with a nanofilter membrane having a rate of 10%, and concentrated to obtain an aqueous vinyl chloride polymer dispersion E2 having a solid content concentration of 48.0% by weight.
Production Example 7 (Production and concentration of vinyl chloride polymer aqueous dispersion by seeded emulsion polymerization)
In a pressure-resistant reactor equipped with a stainless steel stirrer and jacket, an aqueous dispersion containing 105 parts by weight of deionized water, 35 parts by weight of a vinyl chloride polymer seed having a center particle diameter of 0.55 μm, and potassium persulfate 0 .1 part by weight was charged, nitrogen pressurization and nitrogen release were repeated twice, and then degassed under reduced pressure. Next, 100 parts by weight of vinyl chloride was charged, the temperature was increased while stirring, and the reactor pressure was 8.0 kg / cm at 55 ° C. 2 At G, the polymerization reaction was started. When the polymerization conversion rate reached 5% by weight, the addition of a 5% by weight aqueous solution of sodium lauryl sulfate was started, and a total of 8 parts by weight was added until the polymerization conversion rate reached 85% by weight. Reactor pressure is 4.5 kg / cm 2 At the time when the amount dropped to G, 0.6 part by weight of a 25% by weight aqueous solution of sodium lauryl sulfate was added and cooled, and the unreacted monomer was recovered to obtain an aqueous vinyl chloride polymer dispersion having a solid content of 42.0% F was obtained.
The aqueous vinyl chloride polymer dispersion F was subjected to ultrafiltration with a nanofilter membrane having a NaCl rejection of 10% and concentrated to obtain an aqueous vinyl chloride polymer dispersion F2 having a solid content of 56% by weight.
Example 1
A spray dryer having a cylindrical part having an inner diameter of 1,200 mm and a height of 800 mm and a conical part having a height of 780 mm below the chamber, and a rotary disk atomizer having a diameter of 12 cm and a rotational speed of 12,000 rpm in the center of the top. The vinyl chloride polymer aqueous dispersion C2 was spray-dried under the conditions of an inlet temperature of drying air of 167 ° C. and an outlet temperature of drying air of 55 ° C.
The processing speed of the aqueous dispersion is 32.3 kg / hr, the average particle size of the granules is 50 μm, and the bulk density (loose) is 0.54 g / cm. Three The angle of repose was 41 degrees. The paste viscosity was 1,640 cp, the undispersed particle ratio was 0.054% by weight, and the saver spillage was 50 g / 100 seconds.
[0019]
Example 2
Spray drying was performed under the same conditions as in Example 1 except that the drying air inlet temperature was 90 ° C. and the drying air outlet temperature was 50 ° C.
The treatment speed of the aqueous dispersion is 10.0 kg / hr, the average particle size of the granules is 41 μm, and the bulk density (loose) is 0.52 g / cm. Three The angle of repose was 41 degrees. The paste viscosity was 1,660 cp, the undispersed particle ratio was 0.034% by weight, and the saver spillage was 49 g / 100 seconds.
Example 3
Spray drying was performed in the same manner as in Example 1 using the vinyl chloride polymer aqueous dispersion D2 instead of the vinyl chloride polymer aqueous dispersion C2.
The processing speed of the aqueous dispersion is 34.3 kg / hr, the average particle size of the granules is 52 μm, and the bulk density (loose) is 0.50 g / cm. Three The angle of repose was 41 degrees. The paste viscosity was 1,750 cp, the undispersed particle ratio was 0.050% by weight, and the saver spillage was 52 g / 100 seconds.
Comparative Example 1
Spray drying was performed in the same manner as in Example 1 except that the vinyl chloride polymer aqueous dispersion C2 was used instead of the vinyl chloride polymer aqueous dispersion C2.
The treatment speed of the aqueous dispersion is 29.0 kg / hr, the average particle size of the granules is 32 μm, and the bulk density (relaxed) is 0.43 g / cm. Three The angle of repose was 55 degrees. The paste viscosity was 1,640 cp, the undispersed particle ratio was 0.408% by weight, and the saver spillage was 49 g / 100 seconds.
[0020]
Comparative Example 2
Spray drying was performed in the same manner as in Example 1 using the vinyl chloride polymer aqueous dispersion A instead of the vinyl chloride polymer aqueous dispersion C2.
The processing speed of the aqueous dispersion is 29.1 kg / hr, the average particle size of the granules is 34 μm, and the bulk density (relaxed) is 0.42 g / cm. Three The angle of repose was 54 degrees. Further, the paste viscosity was 2,100 cp, the undispersed particle ratio was 0.342% by weight, and the saver spillage was 10 g / 100 seconds.
Comparative Example 3
Spray drying was performed in the same manner as in Example 1 using the vinyl chloride polymer aqueous dispersion E2 instead of the vinyl chloride polymer aqueous dispersion C2.
The processing speed of the aqueous dispersion is 29.0 kg / hr, the average particle size of the granules is 28 μm, and the bulk density (relaxed) is 0.43 g / cm. Three The angle of repose was 53 degrees. The paste viscosity was 4,000 cp, the undispersed particle ratio was 0.822 wt%, and the saver spillage was 12 g / 100 seconds.
Comparative Example 4
Spray drying was performed in the same manner as in Example 1 using the vinyl chloride polymer aqueous dispersion F2 instead of the vinyl chloride polymer aqueous dispersion C2.
The processing speed of the aqueous dispersion is 30.0 kg / hr, the average particle size of the granules is 34 μm, and the bulk density (loose) is 0.42 g / cm. Three The repose angle was 54 degrees. Further, the paste viscosity was 4,300 cp, the undispersed particle ratio was 0.313 wt%, and the saver spillage was 30 g / 100 seconds.
Reference example 1
Spray drying was performed in the same manner as in Example 2 using the vinyl chloride polymer aqueous dispersion C instead of the vinyl chloride polymer aqueous dispersion C2.
The processing speed of the aqueous dispersion was 6.6 kg / hr, and the drying productivity was low. The average particle size of the granules is 22 μm, and the bulk density (loose) is 0.43 g / cm. Three The angle of repose was 53 degrees. The paste viscosity was 1,620 cp, the undispersed particle ratio was 0.034% by weight, and the saver spillage was 50 g / 100 seconds.
The results of Examples 1 to 3 are shown in Table 1, and the results of Comparative Examples 1 to 4 and Reference Example 1 are shown in Table 2.
[0021]
[Table 1]
[0022]
[Table 2]
[0023]
Each of the vinyl chloride resin granules for paste processing having the requirements of the present invention obtained by the methods of Examples 1 to 3 has a bulk density of 0.5 g / cm. Three As described above, it has excellent powder flowability with an angle of repose of 41 degrees, the paste has a low viscosity, and the undispersed particle ratio is extremely small.
In Comparative Example 1, although it is a polymer dispersion having the same particle size distribution as in Example 1, the solid content concentration is as low as 48.6% by weight. Both fluidity and sol dispersibility were poor.
In Comparative Example 2, there is no maximum in the small particle diameter of the polymer particles. In Comparative Example 3, the ratio of the large and small polymer particles is inappropriate. In Comparative Example 4, the polymer particle diameter is 0. Distribution was intermittent in the range of 2 to 5 μm, and the obtained resin granules were inferior in powder flowability and sol dispersibility.
Reference Example 1 is a case of extremely low productivity performed in the same manner as Comparative Example 1 except that the drying temperature conditions were 90 ° C. at the inlet and 50 ° C. at the outlet, and the undispersed particle ratio was small and the viscosity was low. Resin granules giving a paste were obtained.
[0024]
【The invention's effect】
According to the present invention, an aqueous dispersion containing a specific concentration of a vinyl chloride polymer having a specified particle size range and particle size distribution is preferably spray-dried using heated air for drying at a temperature higher than 100 ° C. By the treatment, vinyl chloride resin granules for paste processing having excellent powder fluidity and good dispersibility in a plasticizer during paste preparation can be efficiently produced.
[Brief description of the drawings]
FIG. 1 is a detailed view of a stirring device for measuring the undispersed particle ratio of vinyl chloride resin granules in Examples and Comparative Examples, where (A) is a side view and (B) is a plan view. FIG.
[Explanation of symbols]
1 Stirring blade
2 Petal-like flat wings
3 Fixed ring
4 Stirring shaft
Claims (3)
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JP18493398A JP3707933B2 (en) | 1998-06-30 | 1998-06-30 | Vinyl chloride resin granules for paste processing and manufacturing method thereof |
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JP18493398A JP3707933B2 (en) | 1998-06-30 | 1998-06-30 | Vinyl chloride resin granules for paste processing and manufacturing method thereof |
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JP3707933B2 true JP3707933B2 (en) | 2005-10-19 |
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JP5081366B2 (en) * | 2003-05-15 | 2012-11-28 | 東ソー株式会社 | Polyvinyl chloride resin granules for paste processing |
JP4526843B2 (en) * | 2004-03-19 | 2010-08-18 | 新第一塩ビ株式会社 | Vinyl chloride resin particles for paste and composition thereof |
JP5077396B2 (en) * | 2010-07-14 | 2012-11-21 | 東ソー株式会社 | Method for producing polyvinyl chloride resin granules for paste processing |
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