JPH04248875A - Resin composition for powdery coating compound and its production - Google Patents

Abstract

PURPOSE:To obtain a resin composition for powdery coating compound having excellent stability during preservation, providing a coating film by using a product of this invention by powdery coating, having the surface showing the same flexibility as that of thermoplastic resin in single use, excellent heat resistance and surface hardness. CONSTITUTION:A mixture of (A) a thermoplastic resin containing hydroxyl group and/or amino group and (B) a block isocyanate is dissolved in a solvent heated to a temperature of <=block dissociation temperature of the component B, then the mixture is precipitated by recrystallization method or blending with a poor solvent to give a resin composition for round powder coating compound having 0.3-500mu average particle diameter, where the blending ratio of the component A to the component B is 0.05-1.5 equivalent isocyanate group produced after block dissociation of the component B based on 1 equivalent isocyanate group and/or amino group of the component A, and a method of producing the composition is shown.

Description

【発明の詳細な説明】 【０００１】 【産業上の利用分野】本発明は，可とう性，耐熱性，耐
薬品性等に優れた粉体塗料用樹脂組成物とその製法であ
り，その用途は流動浸漬法，静電塗装法によって金属及
び窯業の物体の被覆に使用するものである。 【０００２】 【従来の技術】従来より可とう性と耐薬品性に優れた熱
可塑性樹脂，特にオレフイン系樹脂をベースとする粉体
塗料は，金属製品の腐食防止，耐薬品性等の付与目的で
広く使用されている。これらの例としては，ベット用バ
ネ，冷蔵庫内網棚，水切り棚，自転車前かご，野菜かご
等日頃我々が目にする所である。しかし，上記のような
耐熱性を要求されない日用品的な分野では，オレフイン
系樹脂のコーテイングで充分上記の目的を達成すること
ができるが，自動車のエンジンルーム，給湯管などのよ
うに金属製品が高温条件で使用される場合，耐熱性が不
十分である。このため耐熱性を要求されるような目的で
は，熱硬化性アクリル，熱硬化性エポキシ等の熱硬化性
樹脂の粉体塗装への使用が増加している。 【０００３】しかし，熱硬化性樹脂は貯蔵時の安定性に
難点があるばかりなく，その塗膜は一般に固く，可とう
性（柔軟性）を要求される用途には不向きである。又，
金属に粉体塗装を施す場合，塗膜の伸びは重要な要素の
一つである，例えば，塗膜の伸びが悪いと，金属製品の
角の部分にエッジ切れが生じたり，複雑な形状の場合に
は，僅かな応力や衝撃によって塗膜が破断し易い。しか
も，粉体樹脂の製造は，通常，常温もしくは液体窒素な
どで冷却しながら機械的に粉砕することにより得られる
。 【０００４】これは，脆性破壊により粉末化する方法で
あるので，その形状が突起を持つものであったり，針状
であったりして形状が不均一となり，これを流動浸漬法
に用いた場合，流動槽内での粉体流動性が悪く，特に薄
層塗装が困難となる。更に金属板と金属パイプを組み合
わせた複雑な形状の塗装の際，塗膜厚さの異なる塗膜面
の均一な製品となり易い。又，静電塗装法に於いても，
粉体の流動性が劣ると粉体貯槽より塗装ガンまで空気に
より物体を移送することが困難となるばかりでなく，帯
電した粉体粒子が均一に被塗装物に付着せず，優れた塗
膜を得ることが出来ない。このような粉末の流動性を改
良する目的で，粉末化した熱可塑性樹脂に微粉末（例：
無機フイラー，特許公開６２−１４３９８０号）を添加
する方法もあるが，この場合流動性は向上するものの得
られる塗膜の光沢が低下し，表面平滑性が著しく低下し
てしまう。 【０００５】 【発明が解決しようとする課題】本発明は，上記したよ
うな機械的粉砕法により得られる粉末樹脂の欠点を改良
し，流動性に優れ薄肉塗装が可能であり，金属表面や窯
業表面に対する密着性に優れると共に，耐熱性，可とう
性（柔軟性）に優れる塗膜を与える粉体塗料用樹脂組成
物を提供することをその課題とする。 【０００６】　 【課題を解決するための手段】本発明者等は，上述のよ
うな改良について検討を重ねた結果，水酸基および／又
はアミノ基を有する熱可塑性樹脂とブロックイソシアネ
ートの混合物を，ブロックイソシアネートの解離温度よ
り低い温度で溶剤に溶解した後，冷却もしくは貧溶剤の
混合により析出したものを粉体塗料用樹脂として使用し
たところ，各種の優れた効果が得られること知見したの
である。 【０００７】即ち，本発明は（Ａ）水酸基及び／又はア
ミノ基を有する熱可塑性樹脂及び（Ｂ）ブロックイソシ
アネート化合物を，（Ｂ）成分のブロック解離温度以下
の温度で加熱した溶剤に溶解した後，析出して得られる
平均粒子径が０．３〜５００μの丸みを帯びた粉体であ
り，（Ａ）成分の水酸基及び／又はアミノ基１当量に対
し（Ｂ）成分のブロック解離後生じるイソシアネート基
が０．０５〜１．５当量からなることを特徴とする粉体
塗料用樹脂組成物である。 【０００８】本発明の粉体塗料用樹脂組成物の製造法は
，二通りあり，第一の方法は第１請求項記載の（Ａ）成
分及び（Ｂ）成分を，（Ｂ）成分のブロック解離温度以
下の温度に加熱した溶剤中で攪拌して（Ａ）成分を溶解
した後，攪拌を継続しながら加熱した後に，減圧して溶
剤を回収しつつ得られる粉末であり，（Ａ）成分の水酸
基及び／又はアミノ基１当量に対して（Ｂ）成分のイソ
シアネート基が０．０５〜１．５当量からなる平均粒子
径が０．３〜５００μの丸みを帯びた粉末であることを
特徴とする粉体塗料用樹脂組成物の製造法である。 【０００９】又，第二の方法は，第一請求項記載の（Ａ
）成分及び（Ｂ）成分を，（Ｂ）成分のブロック解離温
度以下の温度に加熱した良溶剤中で攪拌して（Ａ）成分
を溶解した後，攪拌を継続しながら加熱を停止後に貧溶
剤を加え沈澱して得られる粉末であり，（Ａ）成分の水
酸基及び／又はアミノ基１当量に対して（Ｂ）成分のイ
ソシアネート基が０．０５〜１．５当量からなる平均粒
子径が０．３〜５００μの丸みを帯びた粉末であること
を特徴とする粉体塗料用樹脂組成物の製造法である。 【００１０】本発明で使用する（Ａ）成分の水酸基又は
アミノ基を有する熱可塑性樹脂としては，ポリビニルア
ルコール，エチレン酢酸ビニル共重合体の鹸化物，ブチ
ラール樹脂，ポリエステル，ポリアミド，セルローズ誘
導体等が挙げられる。アミノ基を有する樹脂としてはポ
リアミド，熱可塑性ウレタン等が挙げられる。特に，エ
チレン酢酸ビニル共重合体の鹸化物は，塗膜の諸物性及
びイソシアネート基との反応性等に優れており，（Ａ）
成分として好ましい。尚，エチレン酢酸ビニル共重合体
鹸化物は，酢酸ビニル含有量が３〜５０％，鹸化度が１
０〜１００％のものが好ましい。 【００１１】本発明で使用する（Ｂ）成分のブロックイ
ソシアネート化合物とは，１分子中に少なくとも２以上
のイソシアネート官能基を有する多官能化合物で複数の
イソシアネート官能基が互いに可逆的な形で結合される
か及び／又はイソシアネート官能基がブロック化剤と呼
ばれる適当な化合物を介して結合されたものである。こ
のポリイソシアネートは，脂肪族，脂環式，芳香族及び
複素環式多官能イソシアネートの中から選ぶことが出来
るが，最も良く知られたものとしては，トルエンジイソ
シアネート，ジフェニルメタンジイソシアネート，ヘキ
サメチレンジイソシアネート，イソホロンジイソシアネ
ート等が好ましい。又，これらに付加するブロック化剤
としては，２，６−ジ第３ブチル−４−メチルフエノー
ル，４−第３ブチルフエノール，ｍ−クレゾール，４．
４−チオビス（３−メチル）−６−第３ブチルフエノー
ル，ε−カプロラクタム，ベンゾフエノオキシム，メチ
ルエチルケトンオキシム等を挙げることが出来る。　　
　　　　　　　　　　　　　　　　　　【００１２】尚
，本発明で使用する溶剤としては，使用する（Ａ）成分
の樹脂が溶解する有機溶剤を任意に使用して良く，例え
ば，エチレン酢酸ビニル共重合体及びポリエステル樹脂
は，塩素系の溶剤トリクロロエチレン，四塩化炭素，ト
ルエン，キシレン等が挙げられる。又，本発明での良溶
剤とは，上記のトリクロロエチレン，四塩化炭素，トル
エン，キシレン等のようにそのものを単独で加温するこ
とで容易に（Ａ）成分を溶解する溶剤であり，貧溶剤と
はそのもの単独では（Ａ）成分を溶解する能力を持たな
いものでメタノール，エタノール，イソプロピルアルコ
ール，水等が挙げられる。尚，溶剤の使用量は，使用す
る（Ａ）成分により異なるが，通常（Ａ）成分１重量部
につき２〜１０重量部が適当である。 【００１３】本発明の粉体塗料用樹脂組成物の製造法で
得られる粉末は，平均粒子径が０．３〜５００μで丸み
帯びたものであり，機械粉砕で得られる突起のある樹脂
粉末より優れた流動性値を示し，流動浸漬用樹脂粉末と
して最適である。特に，製造の際には加熱終了後も，樹
脂の溶解した溶液を攪拌しながら，次の操作に移行する
と最良の粉末が得られる。 【００１４】本発明での（Ａ）成分と（Ｂ）成分の配合
割合は，（Ａ）成分の水酸基及び／又はアミノ基１当量
に対し（Ｂ）成分のブロック解離後生じるイソシアネー
ト基が０．０５〜１．５当量となるように配合する。（
Ｂ）成分が０．０５当量より少ないと耐熱性が向上せず
好ましくない，又，１．５当量より多いと貯蔵安定性が
低下し，得られる塗膜も硬くなり過ぎて好ましくない。 尚，使用目的に応じて，各種の添加剤，例えば顔料，無
機フイラー等を任意に混合した粉体塗料用樹脂組成物と
して使用しても良い。以下に，実施例及び比較例を述べ
る。 【００１５】 【実施例１】容量２リットルの加熱及び減圧が可能な攪
拌容器内に，（Ａ）ＭＩ値３０，酢酸ビニル含有量４２
％のエチレン酢酸ビニル共重合体鹸化物（鹸化度９０％
）を２００ｇと（Ｂ）イソホロンジイソシアネートのε
−カプロラクタムブロック化物を１４ｇ，及び，溶剤と
してトリクロロエチレン１ｋｇを仕込み８０℃まで加熱
し，（Ａ）成分を完全に溶解した。その後，攪拌を継続
しながら加熱を停止すると同時に，溶剤を減圧下で除去
し，析出した粉末を濾別，乾燥すると，得られた粉末は
（Ａ）成分の水酸基１当量に対し（Ｂ）成分のイソシア
ネート基が０．１当量の割合からなり，平均粒径５０μ
の丸みを帯びたものであり，かさ比重が０．４８ｇ／ｃ
ｃで（Ａ）成分の水酸基１当量に対し（Ｂ）成分のイソ
シアネート基が０．１当量の割合である本発明の塗料用
樹脂組成物を得る。　 【００１６】 【実施例２】実施例１と同じ（Ａ）成分及び（Ｂ）成分
に溶剤としてトリクロロエチレンと使い同一の方法で溶
解した後，冷却過程中でメチルアルコール５００ｇを徐
々に添加して粉末を析出させた。これを濾別，乾燥して
本発明の粉体塗料用樹脂組成物を得た。この粉末は，（
Ａ）成分の水酸基１当量に対し（Ｂ）成分のイソシアネ
ート基が０．１当量の割合であり，平均粒径が７５μの
丸みを帯びたものであり，かさ比重０．５１ｇ／ｃｃで
ある本発明の粉体塗料用樹脂組成物を得る。 【００１７】 【実施例３】実施例１攪拌容器に１９０℃での溶融粘度
が１．５００ｐｏｉｓｅ，ヒドキシル価５のポリエステ
ル樹脂２００ｇ（日本合成化学商品名：ＫＥ−７１０）
とジフエニルメタンジイソシアネートのメチルエチルケ
トオキシム・ブロック化合物１ｇ，及び溶剤としてトリ
クロロエチレン１ｋｇを仕込み８０℃まで加熱し，樹脂
を溶解させた後，実施例１と同様な手順で樹脂粉末を得
た。出来た粉体は，（Ａ）成分の水酸基１当量に対し（
Ｂ）成分が０．２当量であるかさ比重０．６３ｇ／ｃｃ
で平均粒径が６５μの丸みを帯びた本発明の粉体塗料用
樹脂組成物を得る。 【００１８】 【比較例１】イソホロンジイソシアネートのブロック化
物を除いた以外は，実施例１と同様な手順で樹脂粉末を
得た。粉末の形状は，平均粒径が６５μで丸み帯びたも
のである。 【００１９】 【比較例２】イソホロンジイソシアネトのブロック化物
を１．４ｇとした以外は，実施例１同様な手順で樹脂粉
末を得た。粉末の形状は，平均粒径が７２μで丸み帯び
たものである。 【００２０】 【比較例３】実施例１で用いたエチレン酢酸ビニル共重
合体の鹸化物１００ｇとイソホロンジイソシアネートの
ブロック化物を１５０℃の２本ロール上で５分間混練し
た。 その際，　　粘度が上がってしまい溶融しなくなったの
で粉末樹脂の製造を断念した。 【００２１】 【比較例４】実施例１で使用の（Ａ）成分を，グライン
ドミルで粉砕した粒径２００μものであり，その粒形は
不定形の粉末である。 【００２２】以上，実施例１〜３で得られた本発明の粉
体塗料用樹脂組成物と，比較例１〜４で得られた粉体樹
脂組成物について，次に示す条件で塗膜の伸び率，接着
力及び表面の平滑性を測定し，その結果を【表１】 の測定結果に示す。 （イ）　　塗膜の伸び率及び強度 ２００℃に調節したプレスヒータ上に，予め離型剤とし
てシリコングリースを塗布した縦１５０ｍｍ，横１５０
ｍｍ，厚さ１０ｍｍの鋼板上に，各実施例及び比較例で
得られた粉末樹脂組成物を厚さ５ｍｍに均一に散布し，
塗膜を形成させた。 その塗膜の厚みは約２ｍｍであり，その塗膜を剥離して
ＪＩ−Ｋ−７１１３に従って伸び率（％）及び強度（ｋ
ｇ／ｃｍ２）を測定した。 （ロ）耐熱性 流動浸漬法により厚さ０．８ｍｍ×５０ｍｍ×１５０ｍ
ｍの鉄板を用いて得られた試料を２００℃のオーブン中
に２時間吊り下げ放置後，その表面を目視により測定す
る。　　尚，流動浸漬は，通常の方法で多孔板を通して
流動室に空気を吹き込み，粉末樹脂を流動させ，基材を
懸垂して塗装する。 【００２３】（ハ）　　表面平滑性 流動浸漬法により得られた（ロ）の試料の塗膜の表面状
態を目視によって測定し，その結果を下記の様に表す。 （ニ）　　接着力 流動浸漬法により得られた（ロ）の試料の塗膜表面に，
２５ｍｍ幅に平行ノッチを入れ，引張試験機を用いて５
０ｍｍ／分の引張速度にて，９０度剥離させた時の接着
力（ｋｇ／１０ｍｍ）で示した。 【００２４】 【表１】 【００２５】 【発明の効果】以上に述べたように，本発明は，従来流
動浸漬法に使用が不適当とされていたイソシアネート化
合物をブロック処理を施した（Ｂ）成分と，（Ａ）水酸
基を有する熱可塑性樹脂を加熱した溶剤中で配合するこ
とにより，金属や窯業表面の塗布のための粉体塗料用樹
脂組成物を提供するものである。本発明を実施すること
により，次のような優れた効果が奏される。 【００２６】１．熱硬化性樹脂を含有した粉体塗料用樹
脂組成物であるが，粉体樹脂の製造工程で高温にならな
い為，得られる本発明の粉体塗料用樹脂組成物は，貯蔵
安定性に優れ，長期間保存しても物性が変化しない。 ２．樹脂粉末は，丸みを帯び，粒径のバラッキが小さく
，このため塗装時の粉体の流動性が良く，光沢のある平
滑な塗装面を容易に得ることが出来る。 ３．（Ｂ）成分の使用により，粉体塗装の際の加熱で（
Ａ）成分と（Ｂ）成分の間に架橋を生じ，耐熱性の優れ
た塗膜が得られる。 【００２７】４．塗膜は金属や窯業の表面を保護するに
充分な堅牢性を持つのみならず，柔軟性も備えている。 そのため，複雑な形状をした金属製品にも応用が可能で
ある。 ５．塗膜と金属表面との接着性が強固で高温条件化でも
，接着力が低下することがない。 ６．化学粉砕法で製造するため，ＭＩ値の低い強靱な樹
脂も使用可能であり，エッジカバー性，耐摩擦性に優れ
た塗膜が得られる。以上のような優れた長所を持ち合わ
せた本発明品は，これを流動粉体として，高温に保った
基材を浸漬し被覆させる流動浸漬法に最適である。Detailed Description of the Invention [0001] [Industrial Application Field] The present invention is a resin composition for powder coatings having excellent flexibility, heat resistance, chemical resistance, etc., and a method for producing the same. is used for coating metal and ceramic objects by fluidized dipping and electrostatic coating methods. [Prior Art] Powder coatings based on thermoplastic resins, especially olefin resins, which have superior flexibility and chemical resistance, are used for the purpose of preventing corrosion and imparting chemical resistance to metal products. widely used in Examples of these are things we see every day, such as bed springs, racks inside refrigerators, draining racks, bicycle baskets, and vegetable baskets. However, in the fields of daily necessities that do not require heat resistance, such as those mentioned above, coating with olefin resin is sufficient to achieve the above purpose. Heat resistance is insufficient when used under certain conditions. Therefore, for purposes requiring heat resistance, thermosetting resins such as thermosetting acrylic and thermosetting epoxy are increasingly being used for powder coating. [0003] However, thermosetting resins not only have shortcomings in stability during storage, but also have coatings that are generally hard, making them unsuitable for applications that require flexibility. or,
When applying powder coating to metal, the elongation of the paint film is one of the important factors. For example, if the elongation of the paint film is poor, edge cuts may occur at the corners of the metal product, or problems with complex shapes may occur. In some cases, the coating film is likely to break due to slight stress or impact. Furthermore, powdered resin is usually produced by mechanically pulverizing it at room temperature or while cooling with liquid nitrogen or the like. [0004] Since this is a method of powdering by brittle fracture, the shape may be uneven because it has protrusions or has a needle shape, and if this is used in the fluidized immersion method, , Powder fluidity in the fluidized tank is poor, making thin layer coating particularly difficult. Furthermore, when painting a complicated shape that combines a metal plate and a metal pipe, it is easy to obtain a product with a uniform coating surface having different coating thicknesses. Also, in the electrostatic coating method,
If the fluidity of the powder is poor, it will not only be difficult to transport the object from the powder storage tank to the coating gun using air, but also the charged powder particles will not adhere uniformly to the object being coated, resulting in a poor coating film. I can't get it. In order to improve the fluidity of such powders, fine powder (e.g.
There is also a method of adding an inorganic filler (Japanese Patent Publication No. 62-143980), but in this case, although the fluidity is improved, the gloss of the resulting coating film is reduced and the surface smoothness is significantly reduced. [Problems to be Solved by the Invention] The present invention improves the drawbacks of the powdered resin obtained by the mechanical pulverization method as described above, has excellent fluidity and can be coated thinly, and is suitable for use on metal surfaces and ceramics. The object of the present invention is to provide a resin composition for powder coating that provides a coating film that has excellent adhesion to a surface, as well as excellent heat resistance and flexibility. [Means for Solving the Problems] As a result of repeated studies on the above-mentioned improvements, the present inventors have made a mixture of a thermoplastic resin having a hydroxyl group and/or an amino group and a blocked isocyanate into a blocked isocyanate. They found that various excellent effects could be obtained by using the resin for powder coatings after dissolving it in a solvent at a temperature lower than the dissociation temperature of the compound and precipitating it by cooling or mixing with a poor solvent. That is, the present invention provides a method for dissolving (A) a thermoplastic resin having a hydroxyl group and/or an amino group and (B) a blocked isocyanate compound in a solvent heated at a temperature below the block dissociation temperature of component (B). , is a rounded powder with an average particle diameter of 0.3 to 500μ obtained by precipitation, and isocyanate generated after block dissociation of component (B) per equivalent of hydroxyl group and/or amino group of component (A). This is a resin composition for powder coating, characterized in that the group contains 0.05 to 1.5 equivalents. There are two methods for producing the resin composition for powder coatings of the present invention. The first method is to combine the components (A) and (B) described in the first claim with a block of component (B). It is a powder obtained by dissolving component (A) by stirring in a solvent heated to a temperature below the dissociation temperature, then heating while continuing stirring, and recovering the solvent by reducing the pressure. It is characterized by being a rounded powder with an average particle size of 0.3 to 500μ, consisting of 0.05 to 1.5 equivalents of isocyanate groups in component (B) per 1 equivalent of hydroxyl and/or amino groups in This is a method for producing a resin composition for powder coating. [0009] Furthermore, the second method is based on (A) described in the first claim.
) component and (B) component are stirred in a good solvent heated to a temperature below the block dissociation temperature of component (B) to dissolve component (A), then the poor solvent is added after stopping the heating while continuing stirring. It is a powder obtained by adding and precipitating, and the average particle size is 0.05 to 1.5 equivalents of isocyanate groups in component (B) per 1 equivalent of hydroxyl and/or amino groups in component (A). This is a method for producing a resin composition for powder coating, characterized in that it is a rounded powder with a diameter of 3 to 500 microns. [0010] Examples of the thermoplastic resin having a hydroxyl group or an amino group as component (A) used in the present invention include polyvinyl alcohol, saponified products of ethylene vinyl acetate copolymer, butyral resin, polyester, polyamide, cellulose derivatives, etc. It will be done. Examples of the resin having an amino group include polyamide, thermoplastic urethane, and the like. In particular, the saponified product of ethylene vinyl acetate copolymer has excellent physical properties of the coating film and reactivity with isocyanate groups, and (A)
Preferred as a component. The saponified ethylene vinyl acetate copolymer has a vinyl acetate content of 3 to 50% and a saponification degree of 1.
0 to 100% is preferred. The blocked isocyanate compound as component (B) used in the present invention is a polyfunctional compound having at least two or more isocyanate functional groups in one molecule, and a plurality of isocyanate functional groups are bonded to each other in a reversible manner. and/or isocyanate functional groups are bonded via suitable compounds called blocking agents. The polyisocyanate can be selected from aliphatic, cycloaliphatic, aromatic, and heterocyclic polyfunctional isocyanates, but the most well-known are toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. Diisocyanates and the like are preferred. Blocking agents added to these include 2,6-di-tert-butyl-4-methylphenol, 4-tert-butylphenol, m-cresol, 4.
Examples include 4-thiobis(3-methyl)-6-tert-butylphenol, ε-caprolactam, benzophenoxime, methyl ethyl ketone oxime and the like.
[0012] As the solvent used in the present invention, any organic solvent that dissolves the resin of component (A) used may be used. For example, ethylene vinyl acetate copolymer and polyester resin are Solvents include trichloroethylene, carbon tetrachloride, toluene, xylene, etc. In addition, a good solvent in the present invention refers to a solvent that easily dissolves component (A) when heated alone, such as the above-mentioned trichlorethylene, carbon tetrachloride, toluene, xylene, etc., and a poor solvent. Components that do not have the ability to dissolve component (A) by themselves include methanol, ethanol, isopropyl alcohol, water, and the like. The amount of the solvent to be used varies depending on the component (A) used, but is usually 2 to 10 parts by weight per 1 part by weight of the component (A). [0013] The powder obtained by the method for producing the resin composition for powder coating of the present invention has an average particle size of 0.3 to 500μ and is rounded, and is more round than the resin powder with protrusions obtained by mechanical pulverization. It exhibits excellent fluidity and is ideal as a resin powder for fluidized dipping. In particular, during production, the best powder can be obtained if the solution containing the resin is stirred even after heating is completed before proceeding to the next step. In the present invention, the blending ratio of components (A) and (B) is such that the amount of isocyanate groups generated after block dissociation of component (B) is 0.1 to 1 equivalent of hydroxyl group and/or amino group of component (A). Blend so that the amount becomes 0.05 to 1.5 equivalents. (
If the amount of component B) is less than 0.05 equivalent, the heat resistance will not be improved, which is not preferable, and if it is more than 1.5 equivalent, the storage stability will decrease and the resulting coating film will become too hard, which is not preferable. Incidentally, depending on the purpose of use, various additives such as pigments, inorganic fillers, etc. may be optionally mixed to form a resin composition for powder coating. Examples and comparative examples are described below. [Example 1] In a stirring vessel with a capacity of 2 liters that can be heated and depressurized, (A) MI value 30, vinyl acetate content 42
% saponified ethylene vinyl acetate copolymer (degree of saponification 90%)
) and ε of (B) isophorone diisocyanate.
- 14 g of caprolactam blocked product and 1 kg of trichlorethylene as a solvent were charged and heated to 80°C to completely dissolve component (A). Thereafter, heating is stopped while stirring is continued, and at the same time, the solvent is removed under reduced pressure, and the precipitated powder is filtered and dried. isocyanate groups in a proportion of 0.1 equivalent, and the average particle size is 50μ
It is rounded and has a bulk specific gravity of 0.48g/c.
A resin composition for coating of the present invention is obtained in which the ratio of isocyanate groups in component (B) is 0.1 equivalent to 1 equivalent of hydroxyl group in component (A) in c. [Example 2] The same components (A) and (B) as in Example 1 were dissolved in the same manner using trichlorethylene as a solvent, and then 500 g of methyl alcohol was gradually added during the cooling process to form a powder. was precipitated. This was filtered and dried to obtain a resin composition for powder coating of the present invention. This powder is (
The ratio of the isocyanate group of component (B) to 1 equivalent of hydroxyl group of component A) is 0.1 equivalent, the average particle size is rounded with an average particle size of 75 μ, and the bulk specific gravity is 0.51 g/cc. A resin composition for powder coating of the invention is obtained. [Example 3] Example 1 200 g of polyester resin with a melt viscosity of 1.500 poise at 190°C and a hydroxyl value of 5 (Nippon Gosei Kagaku brand name: KE-710) was placed in a stirring vessel.
1 g of a methyl ethyl ketoxime block compound of diphenylmethane diisocyanate and 1 kg of trichloroethylene as a solvent were charged and heated to 80° C. to dissolve the resin, followed by the same procedure as in Example 1 to obtain a resin powder. The resulting powder has a ratio of (
B) Bulk specific gravity of 0.2 equivalent of component: 0.63 g/cc
A resin composition for powder coating of the present invention having a rounded average particle size of 65 μm is obtained. Comparative Example 1 A resin powder was obtained in the same manner as in Example 1 except that the blocked isophorone diisocyanate was removed. The shape of the powder is round with an average particle size of 65μ. Comparative Example 2 A resin powder was obtained in the same manner as in Example 1, except that 1.4 g of blocked isophorone diisocyanate was used. The shape of the powder is round with an average particle size of 72μ. [Comparative Example 3] 100 g of the saponified ethylene vinyl acetate copolymer used in Example 1 and a blocked product of isophorone diisocyanate were kneaded for 5 minutes on two rolls at 150°C. At that time, the viscosity increased and it became impossible to melt, so we gave up on producing powdered resin. [Comparative Example 4] Component (A) used in Example 1 was ground with a grind mill to have a particle size of 200 μm, and the particle shape was irregular powder. As described above, the powder coating resin compositions of the present invention obtained in Examples 1 to 3 and the powder resin compositions obtained in Comparative Examples 1 to 4 were tested under the following conditions. The elongation rate, adhesive strength, and surface smoothness were measured, and the results are shown in Table 1. (b) Elongation rate and strength of the coating film On a press heater adjusted to 200°C, silicone grease was applied as a mold release agent in advance.
The powdered resin compositions obtained in each example and comparative example were uniformly spread to a thickness of 5 mm on a steel plate with a thickness of 10 mm and a thickness of 5 mm.
A coating film was formed. The thickness of the coating film is approximately 2 mm, and after peeling off the coating film, the elongation rate (%) and strength (k) are determined according to JI-K-7113.
g/cm2) was measured. (b) Thickness 0.8mm x 50mm x 150m by heat-resistant fluidized dipping method
After suspending the sample obtained using a steel plate of 200° C. for 2 hours in an oven at 200° C., the surface of the sample is visually measured. In the fluidized dipping, air is blown into a fluidizing chamber through a perforated plate to flow the powdered resin, and the substrate is suspended and coated. (c) Surface smoothness The surface condition of the coating film of the sample (b) obtained by the fluidized dipping method was visually measured, and the results are expressed as follows. (d) Adhesive force On the coating surface of the sample (b) obtained by the fluidized dipping method,
Parallel notches were made in the width of 25 mm, and 5 mm was tested using a tensile tester.
It was expressed as the adhesive strength (kg/10 mm) when peeled at 90 degrees at a tensile speed of 0 mm/min. [Table 1] [Effects of the Invention] As described above, the present invention provides block treatment for isocyanate compounds that were conventionally considered inappropriate for use in the fluidized dipping method (B). By blending the components and (A) a thermoplastic resin having a hydroxyl group in a heated solvent, a resin composition for a powder coating for coating on metal or ceramic surfaces is provided. By implementing the present invention, the following excellent effects can be achieved. 1. Although the resin composition for powder coatings contains a thermosetting resin, the resulting resin composition for powder coatings of the present invention has excellent storage stability because high temperatures are not raised during the manufacturing process of the powder resin. Physical properties do not change even after long-term storage. 2. The resin powder is rounded and has small variations in particle size, so the powder has good fluidity during painting, and a glossy and smooth painted surface can be easily obtained. 3. By using component (B), heating during powder coating (
Crosslinking occurs between component A) and component (B), resulting in a coating film with excellent heat resistance. 4. The coating is not only tough enough to protect metal and ceramic surfaces, but also flexible. Therefore, it can be applied to metal products with complex shapes. 5. The adhesiveness between the paint film and the metal surface is strong, and the adhesive strength does not decrease even under high temperature conditions. 6. Since it is manufactured using a chemical pulverization method, tough resins with low MI values can also be used, and a coating film with excellent edge coverage and abrasion resistance can be obtained. The product of the present invention, which has the above-mentioned excellent advantages, is most suitable for the fluidized dipping method, in which a substrate kept at a high temperature is dipped and coated in the form of a fluidized powder.

Claims (4)

【特許請求の範囲】[Claims] 【請求項１】　　（Ａ）水酸基及び／又はアミノ基を有
する熱可塑性樹脂及び（Ｂ）ブロックイソシアネート化
合物を，（Ｂ）成分のブロック解離温度以下の温度で加
熱した溶剤に溶解した後，析出させて得られる平均粒子
径が０．３〜５００μの丸みを帯びた粉体であり，（Ａ
）成分の水酸基及び／又はアミノ基１当量に対し（Ｂ）
成分のイソシアネート基が０．０５〜１．５当量の割合
からなることを特徴とする粉体塗料用樹脂組成物。Claim 1: (A) a thermoplastic resin having a hydroxyl group and/or an amino group and (B) a blocked isocyanate compound are dissolved in a solvent heated at a temperature below the block dissociation temperature of component (B), and then precipitated. It is a rounded powder with an average particle diameter of 0.3 to 500μ, obtained by (A
) per equivalent of hydroxyl group and/or amino group of component (B)
A resin composition for a powder coating, characterized in that the isocyanate groups of the components are in a proportion of 0.05 to 1.5 equivalents. 【請求項２】　　第１請求項記載の（Ａ）成分がエチレ
ン酢酸ビニル共重合体鹸化物である粉体塗料用樹脂組成
物。2. A resin composition for powder coating, wherein the component (A) according to claim 1 is a saponified ethylene-vinyl acetate copolymer. 【請求項３】　　第１請求項記載の（Ａ）成分及び（Ｂ
）成分を，（Ｂ）成分のブロック解離温度以下の温度の
溶剤中で攪拌して（Ａ）成分を溶解した後，攪拌を継続
しながら加熱を停止しすると同時もしくは冷却後，減圧
して溶剤を回収しつつ得られる粉末であり，（Ａ）成分
の水酸基及び／又はアミノ基１当量に対して（Ｂ）成分
のイソシアネート基が１．５当量からなる平均粒子径が
０．３〜５００μの丸みを帯びた粉末であることを特徴
とする粉体塗料用樹脂組成物の製造法。Claim 3: Component (A) and (B) according to claim 1.
After stirring the component (B) in a solvent at a temperature below the block dissociation temperature of the component (B) to dissolve the component (A), the heating is stopped while stirring is continued, and at the same time or after cooling, the pressure is reduced and the solvent is dissolved. It is a powder obtained while recovering, and has an average particle size of 0.3 to 500μ, consisting of 1.5 equivalents of isocyanate groups in component (B) per 1 equivalent of hydroxyl and/or amino groups in component (A). A method for producing a resin composition for powder coating, which is characterized by being a rounded powder. 【請求項４】　　第一請求項記載の（Ａ）成分及び（Ｂ
）成分を，（Ｂ）成分のブロック解離温度以下の温度の
良溶剤中で攪拌して（Ａ）成分を溶解した後，攪拌を継
続しながら加熱を停止後に，貧溶剤を加え沈澱させて得
られる粉末であり，（Ａ）成分の水酸基及び／又は１当
量に対して（Ｂ）成分のイソシアネート基が０．０５〜
１．５当量からなる平均粒子径が０．３〜５００μの丸
みを帯びた粉末であることを特徴とする粉体塗料用樹脂
組成物の製造法。Claim 4: Component (A) and (B) described in the first claim.
) component is stirred in a good solvent at a temperature below the block dissociation temperature of component (B) to dissolve component (A), and after stopping heating while continuing stirring, a poor solvent is added and precipitated. It is a powder in which the isocyanate group of component (B) is 0.05 to 1 equivalent of the hydroxyl group and/or of component (A).
A method for producing a resin composition for a powder coating, characterized in that the powder is a rounded powder having an average particle size of 0.3 to 500μ and consisting of 1.5 equivalents.