JP4197367B2

JP4197367B2 - Powder coating composition

Info

Publication number: JP4197367B2
Application number: JP15070798A
Authority: JP
Inventors: 昭彦石井; 圭一山本; 修三阿部
Original assignee: Shinto Paint Co Ltd
Current assignee: Shinto Paint Co Ltd
Priority date: 1998-05-13
Filing date: 1998-05-13
Publication date: 2008-12-17
Anticipated expiration: 2018-05-13
Also published as: JPH11323203A

Description

【０００１】
【発明の属する技術分野】
本発明は、１コートで厚膜が得易く、通常使用に耐える物性を持ちながら、ショットブラスト等で膜が剥がれやすい特徴を持つ塗膜を要求するガスボンベ用に適する粉体塗料組成物に関するものである。
【０００２】
【従来の技術】
従来、ガスボンベ等には溶剤型塗料を塗装していたが、作業性・公害等により現在粉体塗料に置き換わってきており、粉体塗料は物性が非常に良く、また膜厚も厚く付き易いと言う利点はある。
【０００３】
【発明が解決しようとする課題】
従来の溶剤型塗料では、必要とする膜厚を得るために、２回塗りを行う必要があり作業性に問題が出てくる。また溶剤を使用しているため、環境汚染等の問題が発生する。また通常粉体塗料では、一定期間使用後のガスボンベ等の塗り替え時に、前の塗膜を剥離するためのショットブラストで落ちにくく、前の塗膜が残ってしまう不具合が発生する。
【０００４】
【課題を解決するための手段】
そこで、本発明者は形成された塗膜の物性が従来の溶剤型塗料に比べ優れており、なおかつ、ショットブラストによる塗膜の剥離性が通常の粉体塗料に比べ優れている新規な粉体塗料の開発を行った。
【０００５】
その結果、粉体塗料の物性・塗装性はそのままで、ショットブラストによる塗膜の剥離性を良くし、今までのショットブラストの機械による１回の塗膜剥離で、前の塗膜が完全に剥離できる粉体塗料組成物を見いだしたものである。
【０００６】
すなわち、本発明は水酸基末端ポリエステル樹脂（主材樹脂）とブロックイソシアネート（硬化剤）を含有する粉体塗料であって、硬化剤を硬化剤の反応基の数が主材樹脂の水酸基の数の４５〜９０％、好ましくは５５〜８５％になるように含有し、体質顔料を２０ＰＨＲ以上１００ＰＨＲ以下、好ましくは４０ＰＨＲ以上８５ＰＨＲ以下含有すること、また数平均分子量が５００〜５０００の直接硬化に関与しない熱硬化性樹脂あるいは熱可塑性樹脂であり、軟化点が８０〜１５０℃の樹脂を単独あるいは、併用して主材樹脂の５〜４０重量％、好ましくは１０〜２５重量％含有することを特徴とする粉体塗料組成物である。
【０００７】
【発明の実施の形態】
本発明の粉体塗料組成物は、前記のように、主材水酸基末端ポリエステル樹脂、硬化剤樹脂、体質顔料、熱可塑性樹脂、直接硬化に関与しない熱硬化性樹脂等を含有してなるものであり、硬化剤を硬化剤の反応基の数が主材樹脂の水酸基の数の４５〜９０％、好ましくは５５〜８５％となるように含有する。硬化剤の反応基の数が主材樹脂の水酸基の数の４５％未満の時は、ショットブラストによる剥離性は良いが、一般物性が悪く通常の使用に耐えない塗膜となり、逆に９０％を超えるときは、一般物性は良いがショットブラストによる剥離性が非常に悪くなり、いずれも好ましくない。また、体質顔料は２０ＰＨＲ以上１００ＰＨＲ以下、好ましくは４０ＰＨＲ以上８５ＰＨＲ以下含有してなり、含有量が２０ＰＨＲ未満のときは、ショットブラストによる塗膜の剥離が悪くなり、逆に１００ＰＨＲを超えるときは塗膜の剥離は良くなるが、塗膜外観が悪い物となってしまい、いずれも好ましくない。また熱可塑性樹脂及び又は直接硬化に関与しない熱硬化性樹脂は、主材樹脂の５〜４０重量％、好ましくは１０〜２５重量％含有するがこれらの含有量が５重量％未満のときは、ショットブラストによる剥離性が悪く、逆に４０重量％を超えるときは、ショットブラストによる塗膜の剥離性は良いが、一般物性が悪い塗膜となってしまい、好ましくない。
【０００８】
本発明に用いる主材樹脂としては、通常の粉体塗料に用いられる水酸基末端ポリエステル樹脂が好ましい、水酸基価等量としては２５〜５５の物が使用され、例えば日本エステル社製ＥＲ６６１０・ＥＲ６６２０・ＥＲ６５７０・ＥＲ６８００・ＥＲ６６４０・ＥＲ６６５０・ＥＲ７４００・ＥＲ７３００等、大日本インキ化学工業社製Ｍ８０５０・Ｍ８０１０・Ｍ８１００・Ｍ８０５１・Ｍ８０２０・Ｍ８０７５・Ｍ８０２１等、日本ユピカ社製ＧＶ１２０・ＧＶ１５０・ＧＶ７００・ＧＶ７４０・ＧＶ７４６・ＧＶ５００・ＧＶ１１０・ＧＶ１５２等、またそれ以外の粉体塗料用水酸基末端ポリエステル樹脂も使用できる。かかる、水酸基末端ポリエステル樹脂の硬化剤としてはブロックイソシアネートを使用する。イソシアネートとしては脂肪族、芳香族等が使用できＩＰＤＩ・水添ＭＤＩ・ＴＤＩ・ＭＤＩのブロックされた物等が使用できる、例えばヒュルス社Ｂ１５３０・Ｂ１３００マックウォーター社２４ー２４００・２４ー２４３０・２４ー２４３１・２４ー２４５０バイエル社ＣｒｅｌａｎＵＩＣｒｅｌａｎＶＰＬＳ２１５１ＣｒｅｌａｎＶＰＬＳ２００７ＣｒｅｌａｎＶＰＬＳ２１２２ヘキスト社製ＶＸＬ９９３５・ＶＸＬ９９４６等である。
【０００９】
本発明に用いる体質顔料としては、通常塗料に用いられる体質顔料であれば特に制限されないが、硫酸バリウム、炭酸カルシウム等が好ましい。
【００１０】
本発明に用いる熱可塑性樹脂としては、数平均分子量が５００〜５０００であり、常温で固形で８０〜１５０℃で溶融する熱可塑性樹脂であれば特に制限されないが、石油樹脂、キシレン樹脂等脆い樹脂が適している。また、本発明に用いる直接硬化に関与しない熱硬化性樹脂は、数平均分子量が５００〜５０００であり、常温で固形で８０〜１５０℃で溶融する硬化剤と直接硬化反応を起こさないか、ほとんど反応をしない熱硬化性樹脂が使用出来る。ほとんど反応をしない熱硬化性樹脂としては例えば本願硬化剤のイソシアネート基との反応性がポリエステル樹脂の末端水酸基より低いカルボキシル基等を含有する樹脂あるいは固形のエポキシ樹脂等が挙げられる。
本発明の粉体塗料組成物には、上記各成分の外に、通常の粉体塗料において用いられる着色顔料、流動性調整剤、ブロッキング防止剤、紫外線吸収剤、紫外線安定剤、表面調整剤、ワキ防止剤、帯電制御剤、硬化促進剤、エポキシ樹脂等を含有することが出来る。
【００１１】
本発明の粉体塗料組成物の製造方法は、通常の粉体塗料の製造方法と同様で、樹脂、硬化剤、顔料、添加剤等をミキサー等でプレブレンドを行い、次に混練り機を通すことにより、溶融ブレンドを行った後、冷却、粗粉砕、微粉砕を行い後添加の必要なものは後添加を行い、濾過を行って調整することができる。
【００１２】
粉体塗装は、公知の静電粉体塗装方法で塗装することが出来る、例えば、コロナ帯電方式、摩擦帯電方式等により被塗物に塗装することが出来る。コロナ帯電方式の荷電量は、それぞれの塗装物に合わせて設定する。
塗膜形成（焼付）法は、通常の粉体塗料の焼付と同じくそれぞれの塗料に適した焼き付け温度、焼き付け時間に合わせて設定する。
塗装膜厚は、４０〜９０μｍの範囲が好適である。
【００１３】
【実施例】
以下実施例及び比較例に基づいて本発明を説明する。
表１、表２、表３に示す配合組成の実施例１〜８、比較例１〜４の粉体塗料を前記した製造方法で製造し、前記した塗装法及び塗膜形成（焼付）法で塗膜を作成した。
これらの塗膜の性能を試験したところ表１、表２、表３に示すように各実施例の粉体塗料は、通常塗膜物性を測定する、碁盤目試験、衝撃試験、エリクセン試験等において通常の使用に対して、特に問題のある結果は出なかった、また塗膜をショットブラストで剥離するテストでは、塗膜が容易に剥離できガスボンベ用塗料としての要求を充分満たすことが出来た。
表１、表２、表３に示す配合組成の実施例及び比較例
【００１４】
【表１】

【００１５】
【表２】

【００１６】
【表３】

【００１７】
※ １大日本インキ社製水酸基末端ポリエステル樹脂
※ ２日本ユピカ社製水酸基末端ポリエステル樹脂
※ ３日本エステル社製水酸基末端ポリエステル樹脂
※ ４大日本インキ社製水酸基末端ポリエステル樹脂
※ ５日本ユピカ社製酸末端ポリエステル樹脂
※ ６三井石油化学工業社製熱可塑性樹脂
※ ７ヒュルス社製ＩＰＤＩブロックイソシアネート硬化剤
※ ８モンサントン社製フロー剤
※ ９ベンゾインであれば、特に製造会社を問わない。
※１０東都化成社製エポキシ樹脂
※１１日本エステル社製水酸基末端ポリエステル樹脂
※１２大日本インキ社製水酸基末端ポリエステル樹脂
※１３日本エステル社製水酸基末端ポリエステル樹脂
※１４日本エステル社製酸末端ポリエステル樹脂
※１５日本ゼオン社製熱可塑性樹脂
※１６三共有機合成社製ジオクチル錫マレート
※１７シェル社製エポキシ樹脂
※１８マックウオーター社製水添ＭＤＩブロックイソシアネート樹脂
＊１．配合組成における数値は重量部を表す。
＊２．試験法の説明
碁盤目試験Ｋ５４００８．５の方法で残った個数を表示。
衝撃性試験Ｋ５４００８．３．２のデュポン式で評価。
エリクセン試験Ｋ５４００８．２．２の破断距離法。
＊３．上記配合中、水酸基末端ポリエステル樹脂、酸末端ポリエステル樹脂、
ブロックイソシアネート、熱可塑性樹脂等は上記本文中に列記
した樹脂やその他メーカーの同等製品が使用出来る。
＊４．総合判断 ◎：良好 ×：不良
【００１８】
【発明の効果】
本発明の粉体塗料をガスボンベに塗装した場合、今までの粉体塗料では、塗り替え時のショットブラストで、塗膜を完全にはがすのが困難であったが、この粉体塗料で塗装したボンベは、簡単に塗膜の剥離が出来塗り替えが出来る。また通常要求される物性、耐食性も、今まで使用していた溶剤塗料に比べ優れている。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a powder coating composition suitable for a gas cylinder that requires a coating film having a characteristic that a film can be easily peeled off by shot blasting, etc. is there.
[0002]
[Prior art]
Conventionally, solvent-type paints have been applied to gas cylinders, etc., but they are now being replaced by powder paints due to workability, pollution, etc. There is an advantage to say.
[0003]
[Problems to be solved by the invention]
In the conventional solvent-type paint, in order to obtain a required film thickness, it is necessary to apply twice, which causes a problem in workability. Moreover, since a solvent is used, problems such as environmental pollution occur. Moreover, in the case of a normal powder coating, when the gas cylinder or the like after use for a certain period of time is repainted, it is difficult to remove by shot blasting for peeling off the previous coating film, and the previous coating film remains.
[0004]
[Means for Solving the Problems]
Therefore, the present inventor has developed a new powder in which the physical properties of the formed coating film are superior to those of conventional solvent-based coatings, and the coating film peelability by shot blasting is superior to that of ordinary powder coating materials. The paint was developed.
[0005]
As a result, the physical properties and paintability of the powder paint remain the same, and the peelability of the paint film by shot blasting is improved, and the previous paint film is completely removed with a single film peel by the conventional shot blasting machine. A powder coating composition that can be peeled is found.
[0006]
That is, the present invention is a powder coating containing a hydroxyl group-terminated polyester resin (main material resin) and a blocked isocyanate (curing agent), wherein the number of reactive groups of the curing agent is the number of hydroxyl groups of the main material resin. It is contained in an amount of 45 to 90%, preferably 55 to 85%, and an extender pigment is contained in an amount of 20 PHR or more and 100 PHR or less, preferably 40 PHR or more and 85 PHR or less, and does not participate in direct curing having a number average molecular weight of 500 to 5000. It is a thermosetting resin or a thermoplastic resin, characterized by containing 5 to 40% by weight, preferably 10 to 25% by weight of the main material resin alone or in combination with a resin having a softening point of 80 to 150 ° C. The powder coating composition.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
As described above, the powder coating composition of the present invention comprises a main material hydroxyl group-terminated polyester resin, a curing agent resin, an extender pigment, a thermoplastic resin, a thermosetting resin not directly involved in curing, and the like. Yes, the curing agent is contained so that the number of reactive groups of the curing agent is 45 to 90%, preferably 55 to 85% of the number of hydroxyl groups of the main material resin. When the number of reactive groups in the curing agent is less than 45% of the number of hydroxyl groups in the main resin, the releasability by shot blasting is good, but the general physical properties are poor and the coating film cannot withstand normal use. When it exceeds 1, general physical properties are good, but peelability by shot blasting becomes very bad, and neither is preferable. The extender pigment contains 20 PHR or more and 100 PHR or less, preferably 40 PHR or more and 85 PHR or less. When the content is less than 20 PHR, peeling of the coating film by shot blasting deteriorates, and conversely, when the content exceeds 100 PHR, the coating film Although the peeling of the film is improved, the appearance of the coating film is deteriorated, which is not preferable. Further, the thermoplastic resin and / or the thermosetting resin not directly involved in curing is contained in an amount of 5 to 40% by weight, preferably 10 to 25% by weight of the main resin, but when these contents are less than 5% by weight, If the peelability by shot blasting is poor and, on the other hand, it exceeds 40% by weight, the peelability of the coating film by shotblasting is good, but the coating film has poor general physical properties, which is not preferable.
[0008]
The main resin used in the present invention is preferably a hydroxyl-terminated polyester resin used in ordinary powder coatings, and a hydroxyl value equivalent of 25 to 55 is used. For example, ER6610, ER6620, ER6570 manufactured by Nihon Ester Co., Ltd. -ER6800, ER6640, ER6650, ER7400, ER7300, etc. M8050, M8010, M8100, M8051, M8020, M8075, M8021, etc. made by Dainippon Ink & Chemicals, Inc. GV110 / GV152, etc., and other hydroxyl-terminated polyester resins for powder coatings can also be used. Block isocyanate is used as a curing agent for the hydroxyl group-terminated polyester resin. As the isocyanate, aliphatic, aromatic, etc. can be used, and blocked IPDI, hydrogenated MDI, TDI, MDI, etc. can be used. For example, Huls B1530 / B1300 McWater 24-24400-24-2430-24 2431 / 24-2450 Bayer's CrelanUI CrelanVPLS2151 CrelanVPLS2007 CrelanVPLS2122 VXL9935 / VXL9946 manufactured by Hoechst.
[0009]
The extender pigment used in the present invention is not particularly limited as long as it is an extender pigment usually used in paints, but barium sulfate, calcium carbonate and the like are preferable.
[0010]
The thermoplastic resin used in the present invention is not particularly limited as long as it is a thermoplastic resin having a number average molecular weight of 500 to 5000 and solid at room temperature and melted at 80 to 150 ° C., but is a brittle resin such as petroleum resin and xylene resin. Is suitable. Moreover, the thermosetting resin which does not participate in the direct curing used in the present invention has a number average molecular weight of 500 to 5,000 and does not cause a direct curing reaction with a curing agent which is solid at room temperature and melts at 80 to 150 ° C. A thermosetting resin that does not react can be used. Examples of the thermosetting resin that hardly reacts include a resin containing a carboxyl group whose reactivity with the isocyanate group of the curing agent of the present application is lower than the terminal hydroxyl group of the polyester resin, or a solid epoxy resin.
In addition to the above-mentioned components, the powder coating composition of the present invention includes a coloring pigment, a fluidity modifier, an antiblocking agent, an ultraviolet absorber, an ultraviolet stabilizer, a surface modifier, It can contain a crack inhibitor, a charge control agent, a curing accelerator, an epoxy resin, and the like.
[0011]
The production method of the powder coating composition of the present invention is the same as the production method of the ordinary powder coating, and the resin, the curing agent, the pigment, the additive, etc. are pre-blended with a mixer etc., and then the kneading machine is used. By passing the mixture, after melt blending, cooling, coarse pulverization, fine pulverization, and post-addition can be performed, and filtration can be performed for adjustment.
[0012]
The powder coating can be applied by a known electrostatic powder coating method, for example, it can be applied to an object by a corona charging method, a friction charging method or the like. The amount of charge in the corona charging method is set according to each paint.
The coating film forming (baking) method is set in accordance with the baking temperature and baking time suitable for each paint, as in the ordinary powder paint baking.
The coating film thickness is preferably in the range of 40 to 90 μm.
[0013]
【Example】
Hereinafter, the present invention will be described based on examples and comparative examples.
The powder coating compositions of Examples 1 to 8 and Comparative Examples 1 to 4 having the blending compositions shown in Table 1, Table 2, and Table 3 are manufactured by the manufacturing method described above, and the coating method and coating film formation (baking) method described above are used. A coating was created.
When the performances of these coating films were tested, as shown in Table 1, Table 2, and Table 3, the powder coating materials of each example were usually used in cross-cut tests, impact tests, Erichsen tests, etc. There were no particularly problematic results for normal use, and in the test for peeling the coating film by shot blasting, the coating film could be easily peeled off and the requirements for a gas cylinder paint could be fully satisfied.
Examples and Comparative Examples of Formulation Compositions Shown in Table 1, Table 2, and Table 3
[Table 1]

[0015]
[Table 2]

[0016]
[Table 3]

[0017]
* 1 Hydroxyl-terminated polyester resin manufactured by Dainippon Ink Co., Ltd. * 2 Hydroxyl-terminated polyester resin manufactured by Nippon-Eupika Co., Ltd. * 3 Hydroxyl-terminated polyester resin manufactured by Nippon Ester Co., Ltd. * 4 Hydroxyl-terminated polyester resin manufactured by Dainippon Ink Co., Ltd. Polyester resin * 6 Thermoplastic resin manufactured by Mitsui Petrochemical Co., Ltd. * 7 IPDI blocked isocyanate curing agent manufactured by Huls * 8 Flow agent manufactured by Monsanton * 9 No particular manufacturing company as long as it is benzoin.
* 10 Epoxy resin manufactured by Toto Kasei Co., Ltd. * 11 Hydroxyl-terminated polyester resin manufactured by Nihon Ester Co., Ltd. * 12 Hydroxyl-terminated polyester resin manufactured by Dainippon Ink Co., Ltd. * 13 Hydroxyl-terminated polyester resin manufactured by Nihon Ester Co., Ltd. 15 Thermoplastic resin manufactured by Nippon Zeon Co., Ltd. * 16 Dioctyl tin maleate manufactured by Sansha Co., Ltd. * 17 Epoxy resin manufactured by Shell Co., Ltd. * 18 Hydrogenated MDI block isocyanate resin manufactured by McWater Co., Ltd. * 1. Numerical values in the composition indicate parts by weight.
* 2. Test method description
The number remaining by the method of the cross cut test K5400 8.5 is displayed.
Impact test K5400 8.3.2 Evaluation by DuPont type.
Eriksen test K5400 8.2.2 fracture distance method.
* 3. During the above formulation, hydroxyl-terminated polyester resin, acid-terminated polyester resin,
Block isocyanates, thermoplastic resins, etc. are listed in the text above.
Resin and other manufacturers' equivalent products can be used.
* 4. Comprehensive judgment ◎: Good ×: Bad [0018]
【The invention's effect】
When the powder coating material of the present invention is applied to a gas cylinder, it has been difficult to completely remove the coating film by shot blasting at the time of repainting with the conventional powder coating material. Can be easily peeled off and repainted. Also, the physical properties and corrosion resistance normally required are superior to the solvent paints used so far.

Claims

A powder coating containing a hydroxyl group-terminated polyester resin (main material resin) and a blocked isocyanate (curing agent), wherein the number of reactive groups of the curing agent is 45 to 90% of the number of hydroxyl groups of the main material resin. A powder coating composition characterized by containing an extender pigment in an amount of 20 PHR to 100 PHR.

The powder according to claim 1, wherein the hardener is contained so that the number of reactive groups of the hardener is 55 to 85% of the number of hydroxyl groups of the main resin, and the extender pigment is contained in an amount of 40 PHR to 85 PHR. Body paint composition.

It is a thermosetting resin or thermoplastic resin having a number average molecular weight of 500 to 5000 that does not participate in direct curing, and contains a resin having a softening point of 80 to 150 ° C. alone or in combination and 5 to 40% by weight of the main resin. The powder coating composition according to claim 1 or 2, characterized by the above.

It is a thermosetting resin or thermoplastic resin having a number average molecular weight of 500 to 5,000 that does not participate in direct curing, and a resin having a softening point of 80 to 150 ° C. is used alone or in combination and contains 10 to 25% by weight of the main resin. The powder coating composition according to claim 3, wherein: