臥式離心氣流干燥機(jī)的設(shè)計(jì)

臥式離心氣流干燥機(jī)的設(shè)計(jì),臥式離心氣流干燥機(jī)的設(shè)計(jì),臥式,離心,氣流,干燥機(jī),設(shè)計(jì) 附錄一 外文譯文 無(wú)鈷干燥系統(tǒng)的發(fā)展過(guò)程 Johan H.bieleman Sasol Servo BV ,the Netherlands 摘要 在空氣干燥機(jī)用于干燥涂層系統(tǒng)，以催化聚合的過(guò)程，其中鈷羧酸是使用最廣泛的干燥劑。然而，化合物鈷很可能是在美國(guó)國(guó)家毒理學(xué)計(jì)劃中研究的致癌因素，例如硫酸亞鐵鈷。因此，德國(guó)已不再給含鈷油漆授予藍(lán)色天使獎(jiǎng)。其他過(guò)渡金屬羧酸如錳 或鐵基很低的催化效果表明，鈷不能平等作為自氧化聚合反應(yīng)的催化劑。干涂料的實(shí) 驗(yàn)調(diào)查的各種有機(jī)螯合配體對(duì)自氧化過(guò)程中的錳催化性能的影響。錳的活動(dòng)受有機(jī)配體的強(qiáng)烈影響。 新錳基于無(wú)鈷，顯示良好的干燥性能和改進(jìn)的顏色保留干涂料的配位化合物。 1．簡(jiǎn)介 空氣干燥醇酸涂料包含除了主要成分、 醇酸、 色素和溶劑少量的干燥劑。 在干燥加快的漆膜，在自氧化的不飽和脂肪酸含量存在的醇酸樹(shù)脂成分作為基于氧化交聯(lián)過(guò)程。 烘干機(jī)，也指在解決方案中，防水劑添加劑是有機(jī)物溶劑和粘合劑中可溶性有機(jī)金屬化合物?；瘜W(xué)，屬于金屬皂類(lèi)的干燥和它們添加到吹干涂料系統(tǒng)，以加速或促進(jìn)后應(yīng)用固體階段在一個(gè)適當(dāng)?shù)臅r(shí)間內(nèi)從液膜轉(zhuǎn)化。 轉(zhuǎn)換發(fā)生的的聯(lián)編程序系統(tǒng)一個(gè)的過(guò)程將金屬陽(yáng)離子的陰離子的干燥機(jī)、催化氧化交聯(lián)作為承運(yùn)人聯(lián)編程序系統(tǒng)中的一部分。 鈷數(shù)十年來(lái)一直活動(dòng)主要的干燥機(jī)使用中干涂料。但是最近的研究與七水合鈷硫 酸事務(wù)局療效為鈷化合物會(huì)遵守重新分類(lèi)程序。繼最近公布委托指令 2001 年 /59/Ecof 歐洲共同體。 氧化物分類(lèi)使用以下風(fēng)險(xiǎn)提示：R 22/R 43/R 50/R 53。相關(guān)的 鈷烘干機(jī)烘干機(jī)沒(méi)有更改還，因?yàn)樗巧胁磺宄绻衿咚镶捔蛩?，水溶性化合物毒性?shù)據(jù)作為找到的鈷的分類(lèi)。 37 臥式離心氣流干燥機(jī)的設(shè)計(jì) 干燥機(jī)制造商已啟動(dòng)幾個(gè)測(cè)試程序以收集數(shù)據(jù)的生物利用度鈷，用作涂料。還是一個(gè)干燥機(jī)、無(wú)鈷替代方案以取代鈷烘干機(jī)的壓力。在某些情況下含鈷成分不會(huì)獲得批準(zhǔn)獲得環(huán)境獎(jiǎng)項(xiàng)，如德國(guó)藍(lán)色天使獎(jiǎng)。 2．干燥過(guò)程及干燥影響 醇酸漆的干燥過(guò)程是緩慢蒸發(fā)中揮發(fā)性的結(jié)果，在第二個(gè)步驟中化學(xué)干燥會(huì)發(fā)生。 醇酸樹(shù)脂的氧化交聯(lián)過(guò)程發(fā)生的 H-原子中的自由基反應(yīng)從亞油酸的雙亞甲組提取的葡萄酒，結(jié)果基采取了大氣氧和從過(guò)氧化物。在過(guò)氧化物與鈷催化劑降低到烷氧基和 過(guò)氧自由基。 這些自由基窗體交聯(lián)的重組過(guò)程稱為"自氧化交聯(lián)過(guò)程"(圖 2)。 圖 1 “自氧化”反應(yīng)方程式 顯然"自氧化"一詞已被定義為一個(gè)無(wú)催化氧化反應(yīng)的過(guò)程。 圖 2 在自氧化交聯(lián)過(guò)程中醇酸樹(shù)脂的反應(yīng)變化 38 臥式離心氣流干燥機(jī)的設(shè)計(jì) 但是，自氧化反應(yīng)發(fā)生重大率僅在面前的一種催化劑，如過(guò)渡金屬提涂料的干燥、自氧化過(guò)程通過(guò)添加烘干機(jī)的加速。沒(méi)有這些干燥的催化劑漆層可能要幾個(gè)月后才能完成干燥。 更詳細(xì)化學(xué)干燥氧化法可以通過(guò)結(jié)合在一起的四個(gè)步驟來(lái)表示: l 步驟 1： 誘導(dǎo)期 l 步驟 2：過(guò)氧化物形成 l 步驟 3: 過(guò)氧化物分解自由基 l 步驟 4: 聚合 從這種涂料應(yīng)用直到電影開(kāi)始吸收空氣中的氧的時(shí)間測(cè)量誘導(dǎo)步驟。吸收的氧窗 體過(guò)氧化物跨聯(lián)編程序(步驟 2) 中的共軛雙鍵。 當(dāng)該過(guò)氧化物開(kāi)始分解時(shí)，就形成了交聯(lián)站點(diǎn)。交聯(lián)在聚合過(guò)程中隨著粘度迅速增加。 第 2 和第 4 步最有效地進(jìn)行樹(shù)脂含共軛的雙鍵 ；但是，非共軛樹(shù)脂顯示還有些反應(yīng)。在這種情況下多個(gè)的雙鍵可能會(huì)導(dǎo)致激活的各種亞甲組重新排列位置的非共軛雙鍵、取決于雙鍵的原始位置。 步驟 1 和 2 使干燥的速度大大提高。 由于他們對(duì)氧化還原反應(yīng)的敏感性的氧進(jìn)行作為干燥機(jī)系統(tǒng)中的金屬。烘干機(jī)也激活的過(guò)氧化物形成；假定是多價(jià)金屬是以雙鍵，增加氧化易感性的關(guān)聯(lián)。鈷干燥機(jī)的增加減少了能源所需使一個(gè)不飽和樹(shù)脂氧吸收激活。 活性氧滲透傾向于過(guò)氧化物的形成。不久，過(guò)氧化被形成及其烷氧基催化反應(yīng)中 的分解(圖 3) 圖 3 自氧化交聯(lián)過(guò)程中的反應(yīng) 39 臥式離心氣流干燥機(jī)的設(shè)計(jì) 基于長(zhǎng)油醇酸樹(shù)脂的環(huán)境照顧裝飾涂料的干燥系統(tǒng)通常使用一個(gè)鈷/鋯/鈣組合干 燥機(jī)。鈷是活性干燥劑, 但是，為了改善通過(guò)干燥、硬度和穩(wěn)定性，鋯和鈣的輔助干燥中正在使用鈷結(jié)合。 鈷烘干機(jī)的潛在替代產(chǎn)品的基本特征。 基本上，干燥機(jī)金屬可分為兩個(gè)組：活動(dòng)烘干機(jī)和輔助干燥。這種差異應(yīng)視為任意它們之間不存在大量的重疊。 在環(huán)境溫度氧攝取、過(guò)氧化形成和過(guò)氧化分解推廣活動(dòng)烘干機(jī)。 輔助烘干機(jī)不顯示催化自己在周?chē)臏囟认?，但提高活?dòng)的干燥機(jī)金屬的活動(dòng)。原發(fā)性干燥機(jī)性能報(bào)告了各種過(guò)渡金屬。 但是，僅錳找到了大量的實(shí)際使用。 沒(méi)有該替代烘干機(jī)-為金屬羧酸-類(lèi)似于中鈷的性能。 但是，反應(yīng)以及對(duì)顏色相同的過(guò)渡金屬的影響等屬性與主要是有關(guān)化學(xué)成分的復(fù) 合金屬。由于"自由金屬陽(yáng)離子"并不存在于解決方案，這是可以理解的。金屬離子始終圍繞陰離子、溶劑分子或其他配體組。 純羧酸的大多是數(shù)商業(yè)烘干機(jī)。但是，對(duì)于某些應(yīng)用程序錳基于強(qiáng)螯合配體與組成如找到了商業(yè)使用、配體將扮演重要的角色的這種化合物催化氧化干燥。強(qiáng)螯合配體對(duì)催化活性通過(guò)改變電子密度的復(fù)雜的離子等金屬中心及其潛在的氧化還原。 下一節(jié)將對(duì)干燥機(jī)的各種錳的成分，使用有機(jī)配體。 3．實(shí)驗(yàn)性 3.1 過(guò)程和使用的材料 對(duì)涂料的各種干燥的影響已被計(jì)算，使用不同干等體系的涂料。在指定為標(biāo)準(zhǔn)漆 的長(zhǎng)油油漆組成如表 1 所示。干燥劑被添加到下階段。 這兩個(gè)商用油漆無(wú)干燥機(jī)由這次測(cè)試的廠商提供，以及準(zhǔn)備進(jìn)行系統(tǒng)"新鮮色漆 和清漆用漆基"已被使用。 干燥性能已確定根據(jù) ASTM 或使用干燥的錄像機(jī)的類(lèi)似過(guò)程。下面的過(guò)程使用了： 1．干燥的錄音機(jī)。干燥條件：23℃/50℃ 相對(duì)濕度。使用的儀器是直線的錄像機(jī)。 后干燥階段被考慮。 階段 a：涂料流一起、 濕邊緣時(shí)間。 階段 b：一條線是可見(jiàn)，油漆開(kāi)始聚合：無(wú)塵。階段 c：使翻錄電影：以自由或表面干。 階段 d：表面路徑： 通過(guò)干或總干。 2．干燥進(jìn)一步成立的"拇指測(cè)試"，并根據(jù) ASTM D1640。 40 臥式離心氣流干燥機(jī)的設(shè)計(jì) 電影的 Konig 硬度被評(píng)估通過(guò)鐘擺阻尼測(cè)試根據(jù) DIN53157。一個(gè)玻璃面板是 涂有 60 濕膜，在 23℃，相對(duì)濕度 50％，硬度條件下保持發(fā)展的時(shí)間與一科尼格擺監(jiān)測(cè)。振蕩時(shí)間的測(cè)量，以減少?gòu)淖畛醯?6 °?3 °是在幾秒鐘內(nèi)給出偏轉(zhuǎn)。 鈷-鋯-鈣干燥機(jī)組合已作為參考，使用金屬比率后，除非另有說(shuō)明。 0.06 Co 0.3zr 0.1Ca 這種組合是基于對(duì) 10 鈷，鋯，鈣 18 10 商用級(jí)別的混合物。這兩個(gè)商業(yè)，以及金屬配合物作為實(shí)驗(yàn)已被使用。詳情將載于表和數(shù)字。 3.2 結(jié)論和討論 3.2.1 鈷與錳干燥機(jī) 在下面的表 1 中顯示演示與干燥機(jī)在白宮漆，制定根據(jù)這種標(biāo)準(zhǔn)的漆，表 1 中 的錳鈷催化作用直接比較。 表 1 在白色醇酸樹(shù)脂漆中 Mn 與 Co 效果 活潑的干 輔助干燥 無(wú) 塵 ( 小 無(wú) 軌 ( 小 總共干燥 白度指數(shù) 硬度(s/k) 燥劑 劑 時(shí)) 時(shí)) 時(shí)間 0.08Co 0.4zr 1.30 2.00 3.30 78 52 0.2Ca 0.08Mn 0.4zr 7.15 9.45 15.15 73 29 0.2Ca 鈷與錳在同一金屬劑量對(duì)干燥機(jī)干燥性能有不利影響，白度和硬度。顯然 不宜以改變。出于實(shí)際應(yīng)用的 7 個(gè)小時(shí)以上的無(wú)塵時(shí)間將導(dǎo)致塵埃粒子附著在干燥涂層。此外，長(zhǎng)期粘性，無(wú)干燥時(shí)間的增加，總的賠償風(fēng)險(xiǎn)增加。 3.2.2 錳-聯(lián)吡啶配合物 錳配合物已被報(bào)告為有效干涸。錳化合物和螯合劑的化合物得到了廣泛的商業(yè)應(yīng)用，在聚氨酯清漆醇酸樹(shù)脂的實(shí)例，以及在水性醇酸樹(shù)脂漆。這些錳的化合物，而不是鈷催干劑使制定的淺色聚氨酯醇酸清漆。最近，錳的復(fù)雜活動(dòng)特殊性已被確定，作 者對(duì) Mn-bipy 復(fù)雜的結(jié)構(gòu)，提出了投影圖 4。 41 臥式離心氣流干燥機(jī)的設(shè)計(jì) 圖 4 Mn-biby 的結(jié)構(gòu) 在鈷催干劑與聚氨酯配合使用清晰的深色清漆醇酸樹(shù)脂和光的原因是缺乏吸引 力。以 Mn - hipy 色彩，而不是在相當(dāng)大的改進(jìn)合作的結(jié)果。這種改善只是在液體清漆可見(jiàn); 沒(méi)有在硬化涂層的差異已被發(fā)現(xiàn)。相對(duì)于錳羧酸在干燥速度顯著改善可以看到(見(jiàn)表 2)。該錳 hipy 復(fù)雜也適用于水性涂料的基礎(chǔ)上的短油醇酸樹(shù)脂乳液。 這兩種樹(shù)脂體系，聚氨酯醇酸樹(shù)脂和短油醇酸樹(shù)脂乳液，有共同的物理干燥是非常重要的，而交聯(lián)的膜的形成和硬度的貢獻(xiàn)是相當(dāng)?shù)停鴮?duì)勞醇酸樹(shù)脂為基礎(chǔ)的系統(tǒng)。 表 2 Mn-bipy 在含有基醇酸聚氨酯的家具中的影響 活潑的干燥劑 輔助干燥劑 總共干燥時(shí)間(小時(shí)) 固體漆 0.06Co 0.3Zr 0.1Ca 2.00 15 0.06Mn 0.3Zr 0.1Ca 5.30 6 0.03Mn-bipy 0.3Zr 0.1Ca 1.30 6 干燥速度使用錳 hipy 已記錄在色素漆的基礎(chǔ)上，聚氨酯醇酸樹(shù)脂(見(jiàn)表 3)相似的積極影響。然而，Mn-hipy 有負(fù)面影響的白度。 42 臥式離心氣流干燥機(jī)的設(shè)計(jì) 表 3 在白色醇酸樹(shù)脂漆中 Mn-bipy 在聚氨酯醇酸樹(shù)脂中的影響效果 活潑的干燥劑 輔助干燥劑 總共干燥時(shí)間(小時(shí)) 白度 0.06Co 0.3Zr 0.1Ca 4.45 79 0.06Mn 0.3Zr 0.1Ca 9.30 77 0.03Mn-bipy 0.3Zr 0.1Ca 4.15 73 此外，比較數(shù)據(jù)已被記錄在一個(gè)標(biāo)準(zhǔn)的白色油漆，醇酸樹(shù)脂的基礎(chǔ)上 (見(jiàn)表 4)。 盡管在干燥時(shí)間可以看到同樣的改善，但整體表現(xiàn)仍然不足，需要進(jìn)一步改善。像在聚氨酯醇酸樹(shù)脂漆，一個(gè)復(fù)雜的聯(lián)吡啶上的白度產(chǎn)生負(fù)面影響已經(jīng)確定，也是在勞醇 酸油漆。此外，漆膜仍太軟。 表 4 在白色醇酸樹(shù)脂漆中 Mn-bipy 在羅醇氨樹(shù)脂中的影響效果 活潑的 總共干燥時(shí) 白度指 硬 輔助干燥劑 無(wú)塵(小時(shí)) 無(wú)軌(小時(shí)) 度 干燥劑 間 數(shù) (s/k) 0.08Co 0.3Zr 0.1Ca 2.00 2.30 4.45 80 36 0.08Mn 0.3Zr 0.1Ca 10.00 13.00 15.15 78 29 0.03 0.3Zr 0.1Ca 5.00 7.00 10.00 72 21 Mn-bipy 顯然，錳催化效率提高利用聯(lián)吡啶配體。但是，進(jìn)一步的改善是必要的，以便能夠使用和錳，鈷，而不是基于干燥器。 3.2.3 錳-聚配體復(fù)合物 配體與配體成分變化大評(píng)估。聯(lián)吡啶是一種典型的強(qiáng)場(chǎng)配體，形成穩(wěn)定的復(fù)合物與錳。在干燥特性的進(jìn)一以步改善將達(dá)到使用兩個(gè)或兩個(gè)以上配體組成：通常是強(qiáng)場(chǎng)配體和一個(gè)弱場(chǎng)配體。下一步改善干燥特性的另一個(gè)優(yōu)點(diǎn)是使用混合配體儲(chǔ)存穩(wěn)定性 的改善，低粘度，使高濃度達(dá)到少雨成分，而在復(fù)雜的金屬濃度為 6％錳。 下面的測(cè)試結(jié)果證明了“聚配型錳配合物”的“錳小巴指出”起生效。對(duì)干燥，硬度以及顏色速度是積極的影響使用聚配體為基礎(chǔ)，而不是僅僅聯(lián)吡啶錳(表 5) 43 臥式離心氣流干燥機(jī)的設(shè)計(jì) 表 5 在白色醇酸樹(shù)脂漆中 Mn-Plb 在聚氨酯醇酸樹(shù)脂中的影響效果 活潑的 輔助干燥劑 無(wú)塵(小時(shí)) 無(wú)軌(小時(shí)) 總共干燥時(shí) 白 度 指 硬 干燥劑 間 數(shù) 度 (s/ k) 0.06Co 0.3Zr 0.1Ca 2.00 2.30 4.45 80 36 0.06Mn 0.3Zr 0.1Ca 10.00 13.00 15.15 78 29 0.03 0.3Zr 0.1Ca 5.00 7.00 10.00 76 21 Mn-bipy 0.03 0.3Zr 0.1Ca 4.20 5.45 8.00 77 24 Mn-blp 醇酸樹(shù)脂涂料在羅湖干燥仍稍遜使用錳，鈷。進(jìn)一步改善完成修改樹(shù)脂組成;利 用介質(zhì)油醇酸或勞混合醇酸樹(shù)脂和醇酸樹(shù)脂莫。 在密蘇里州的干燥特性醇酸樹(shù)脂涂料是為錳，鈷作為干燥器乘客聯(lián)絡(luò)小組(表中 的提法比較 6 和 7)。利用與錳乘客聯(lián)絡(luò)小組一起輔助干燥器作用是有限的使用劑量不能保證在評(píng)估這些醇酸樹(shù)脂涂料莫。因此，在干燥催化劑總額可能減少 2.4％至 0.3％ (表 6)。 表 6 白漆在中期油基醇酸 干燥機(jī) 固體中 干燥原 S．b=2 總共干 3 月后 硬 度 W-I 中活躍 活躍的 料成本 9.7% 燥時(shí)間 在 23℃ (s/k) 的干燥 干燥劑 指數(shù) 的干燥 劑 時(shí)間 Co-Zr- 1.2%Co 0.075 100 1.86 4.30 7 63 80 Ca Mn-plg 6%Mn 0.04 60 0.40 5 6 57 81.5 44 臥式離心氣流干燥機(jī)的設(shè)計(jì) 表 7 半光澤黑色漆的基礎(chǔ)上，連鎖停止中等油醇酸樹(shù)脂 干 燥 機(jī) 固 體 中 干 燥 原 S ．b=29 總 共 干 3 月后在 硬 度 中 活 躍 活 躍 的 料 成 本 .7% 燥時(shí)間 23℃ 的 (s/k) 的 干 燥 干燥劑 指數(shù) 干 燥 時(shí) 劑 間 Co-Zr- 1.2%Co 0.09 100 2.78 4 4 106 Ca Mn-plg 6%Mn 0.09 106 1.11 9 6 113 4. 結(jié)論 有機(jī)配合物的前途在于提供錳鈷催化劑作為替代的功能。在測(cè)試的配方，新錳聚配體干燥介質(zhì)提供了類(lèi)似的石油總干醇酸樹(shù)脂涂料的特點(diǎn)，而不會(huì)造成液體或固化涂料的不利影響。新的干燥性能優(yōu)于傳統(tǒng)的錳對(duì)干燥器。 45 臥式離心氣流干燥機(jī)的設(shè)計(jì) 附錄二 外文原文 Progress in the Development of Cobalt-free Drier Systems Johan H.bieleman Sasol Servo BV ,the Netherlands Summary Driers are used in air-drying coating systems to catalyze the polymerization process. cobalt-carboxylates are the most widely used driers . However , cobalt cornpounds may indirectly be implicated as carcinogen suspects as aresult of studies in the U.S.A , in the national toxicology program using cobalt sulphate heptahydrate . Hence , Germany is no longer granting the Blue Angel award to cobalt-containing paints . Other transition metal carboxylates such as based on manganese or iron show much lower catalytic effects and cannot equalize cobalt as a catalyst in autoxidation polymerization reactions . The effect of various organic chelating ligands on the catalytic properties of manganese in autoxidation processes was investigated experimentally in air-drying paints . The activity of manganese is strongly effected by organic ligands . New manganese based coordination compounds enable the formulation of co-free air-drying paints , which show good drying performances and improved color retention . 1 Introduction Air drying alkyd paints contain besides the main constituents , alkyd resins(binders) , pigment and solvents small amounts of driers . The driers speed up the oxidative cross-linking process of a paint film , based on the autoxidation of the unsaturated fatty acids , which are present as constituents of alkyd resins . Driers , also referred to as siccatives when in solution , are organo-metallic compounds soluble in organic solvents and binders . Chemically , driers belong to the class of metal soaps and they are added to air-drying coating systems to accelerate or promote after application the transformation from the liquid film into the solid stage within an appropriate time . The transformation occurs by oxidative cross-linking of the binder system , a process , which is catalysed by the metallic cation of the drier .The anionic part of the drier molecule serves as the carrier , to solubilize the drier in the binder system . For deCADes cobalt has been the main active drier used in air-drying paints . However as the result of recent studies with cobalt sulphate heptahydrate , cobalt compounds are subject to reclassification procedures . Following the recently published commission 46 臥式離心氣流干燥機(jī)的設(shè)計(jì) Directive 2001 /59/Ecof the European Community . Cobalt oxide is classified using following risk phrases : R 22/R 43/R 50/R 53 . The classification for cobalt driers have not been changed yet , as it is still unclear if the toxicity data as found for water soluble compounds like Cobalt sulphate heptahydrate , are relevant for cobalt driers . Drier manufacturers have initiated several test-procedures in order to collect data for the bioavailability of cobalt , used as a drier in paints .Nevertheless , the pressure to replace cobalt driers with cobalt-free alternatives is growing . In some case cobalt-containing compositions will not be granted for environment awards ,like for the Blue Angel Germany . 2 The drying process and the effect of driers The drying process of alkyd paint is the result of the slow evaporation of the volatile compoments and in a second step chemical drying takes place . The oxidative cross-linking process of alkyd resins occurs vin a radical reaction in which H-atoms are abstracted from the double methylene group of linoleic acid . The resulting radicals take up atmospheric oxygen and from hydroperoxides . The hydroperoxides degrade with cobalt catalyst into alkoxy and peroxy radicals . These radicals form cross-links by recombination . This process is known as “the autoxidation cross-link process” (figure 2) . Apparently the term “ autoxidation ” has been defined as an non-catalyzed oxidation reaction of a substrate exposed to the oxygen of the air . Figure 1.General reactions for “autoxidation ” reactions . 47 臥式離心氣流干燥機(jī)的設(shè)計(jì) Figure 2.Schematic presenation of the autoxidation cross-linking process of alkyd resins However , autoxidation reactions occur at significant rates only in presence of a catalysts , such as a transition metal [ ref . 1 , 3 , 4 ] .The autoxidation process referring to the drying of paints is accelerated by addition of driers . Without these drying catalysts the paint layer may dry only after some months ; with driers this is accomplished within a few hours . More in a detail , chemical drying by oxidation can be through as a combination of four steps : l Step 1 : Induction period l Step 2 : Peroxide formation l Step 3 : Peroxide decomposition into free radicals l Step 4 : Polymerization The induction step is measured from the time the coating is applied until the film begins to absorb oxygen from the air . The absorbed oxygen forms peroxides across the conjugated double bonds in the binder (Step 2) . When the peroxides start to decompose , active cross-linking sites are formed . As crosslinking proceeds during the polymerisation , the viscosity increases rapidly . 48 臥式離心氣流干燥機(jī)的設(shè)計(jì) Step 2 and 4 proceed most effectively with resins containing conjugated double bonds ; however , non-conjugated but poly-unsaturated resins show also some reactivity . In such a case the multiple double bonds may cause the activation of the various methylene groups , to rearrange the position of the non- conjugated double bonds , depending on the original position of the double bonds . The step 1 and 2 are accelerated dramatically by the presence of driers . The mutivalent metals in the drier system act as oxygen carries because of their susceptibility to redox reactions . Driers also activate the formation of peroxides ; assumed is the multivalent metal is associated to the double bonds , increasing the oxidation susceptibility . The addition of cobalt drier reduces the energy , which is necessary for the activation of the oxygen absorption by an unsaturated resin , with a factor 10 [ ref . 1 , 5] . The penetration of activated oxygen into the film favors the peroxide formation . As soon as peroxide are formed their decomposition in a metal-catalysed reaction to alkoxy (RO · ) and peroxy radicals (ROO · ) takes palace (figure 3) . Figure 3 . Reactions during the autoxidation cross-linking process 49 臥式離心氣流干燥機(jī)的設(shè)計(jì) Drier systems for ambient cared decorative paints based on long oil alkyd resins are usually siccativated using a cobalt / zirconium / calcium combination drier . Cobalt is the active drier . However , in order to improve through-drying , hardness and stability , auxiliary driers , like zirconium and calcium , are being used in conjunction with cobalt . General characteristics of potential alternatives to cobalt driers . Essentially , drier metals can be divided into two groups : active driers and auxiliary driers . This difference should be considered arbitary as a considerable amount of overlap exists between them . Active driers promote at ambient temperatures oxygen uptake ,peroxide formation and peroxide decomposition . Auxiliary driers do not show catalytic themselves at ambient temperatures , but enhance the activity of the active drier metals . Next to cobalt ,various transition metals have been reported as having primary drier properties . However , only manganese has found substantial practical use . None of the alternative driers-as metal carboxylates-resemble in performance to cobalt . The limitations of the alternatives in relation to the application in paints are summarized as follows : However , the reactivity as well as properties like effect on colour of the same transition metal are largely related to the chemical composition of the metal compound [ref . 6 ] . This is understandable as “ free metallic cations ” do not exist in solution . The metal ions are always surrounded by anions , by solvent molecules or by other ligand groups . Most commercial driers are pure carboxylates . However , for some applications manganese based compositions with strong chelating ligands such as bipyridine have found commercial use .The ligand plays an important role in the catalytic oxidative drying of these compounds (ref . 7) . Strongly chelating ligands effect the catalytic reactivity by altering the electron density at the metallic center of a complex ion and so its redox potential . 50 臥式離心氣流干燥機(jī)的設(shè)計(jì) Next section will be addressed to the performance as a drier various manganese based compositions , using organic ligands . 3 Experimental 3.1 Procedure and used materials The effect of various driers on the drying of paints has been evaluated , using different air-drying paint systems . The composition of the long-oil paint , designated as standard paint , is shown in table 1 . The drier is added to the paint during the let-down stage . As paint systems both commercially available paints , supplied by the manufacturer for this test without drier , as well as prepared “ fresh paints and varnishes ” have been used . The drying performance was determined according to ASTM or similar procedures , using a drying recorder . Following procedures have been used : 1: the drying recorder . Drying condition : 23℃/50℃ relative humidity . The used instrument is a straight-line recorder . Following drying stage are being considered : Stage a – the paint flows together , the wet-edge time . Stage b – a line is visible , the paint begins to polymerize : dust-free . Stage c – ripped film : take-free or surface-dry . Stage d – surface path : through dry or total dry . 2: the drying was further established by the “ thumb-test ” and according to ASTM D1640 . The Konig hardness of the films was assessed by using the pendulum damping test according to DIN53157 . A glass panel was coated with a 60 mm wet film ,kept under conditions of 23℃ and 50% RH and the hardness development in time was monitored with a Konig pendulum . The oscillation time measured to reduce the deflection from initial 6°to 3°is given in seconds . A cobalt-zirconium-calcium drier combination has been used as reference , using following metal ratio , unless otherwise indicated . 0.06 Co 0.3zr 0.1Ca This combination is based on a mixture of commercially available grades of Co 10 , Zr 18 and Ca 10 . 51 臥式離心氣流干燥機(jī)的設(shè)計(jì) Both commercial as well as experimental metal complexes have been used . Details will be presented in the tables and figures . 3.2 Results and discussion 3.2.1 Co vs Mn drier A direct comparison demonstrating the catalytic effect of Co versus Mn drier in a white house paint , formulated according to the standard paint according to table 1 is shown in following table 1 . Replacing Co drier with Mn drier at same metal dosage has a detrimental effect on the drying performance , whiteness and hardness .Obviously Mn is unsuitable to replace Co drier . For practical application a dust-free time of over 7 hours will result in adhesion of dust particles in the dried coating . Moreover , the long tack-free and total dry time increase the risk of damages to the paint film and the appearance . 3.2.2 Manganese-bipyridine complexes Manganese complexes have been reported as effective dries [ ref . 6 ] . Compounds of Mn and chelating compounds , like 1 , 10-phenantroline and bipyridine , have found widespread commercial application , for instance in urethane alkyd varnishes as well as in waterborne alkyd paints . The application of these manganese compounds instead of cobalt driers enables the formulation of light colored urethane alkyd varnishes . Recently the active speciesc of the Mn-bipy complex has been determined as being [Mn4O2 (2ethylhexanoate)6 (bipy)2 ] [ref . 7] . A projection of the structure of the Mn-hipy complex is presented in figure 4 . 52 臥式離心氣流干燥機(jī)的設(shè)計(jì) Figure 4 . Structure Mn-hipy complex . The use of Co driers in conjunction with clear urethane alkyd resins in dark colored varnishes and are for optical reasons less attractive . Using Mn-hipy instead of Co results in considerable improvement in color . This improvement is just visible in the liquid varnish ; no Differences in the hardened coating have been found . Compared to the Mn carboxylate remarkable improvement in drying speed can be noticed (table 2 ) . The Mn-hipy complex is also applicable in waterborne coating , based on