測(cè)定水性涂料中VOC的幾點(diǎn)建議

1、百家論壇測(cè)定水性涂料中VOC 的幾點(diǎn)建議尹建武(北京微量化學(xué)研究所分析測(cè)試中心, 100091摘要:不同標(biāo)準(zhǔn)和測(cè)試方法會(huì)引起VOC 值的差異, 針對(duì)水性涂料的特點(diǎn), 對(duì)影響VOC 測(cè)定的因素作了試驗(yàn), 提出測(cè)試步驟和合理方法, 并統(tǒng)一計(jì)算方法, 消除這些差異。關(guān)鍵詞:水性涂料; VOC ; 測(cè)定1不同的標(biāo)準(zhǔn)引起VOC 值的差異VOC 一項(xiàng)指標(biāo), 論的國(guó)家強(qiáng)制性和業(yè)水性涂料標(biāo)準(zhǔn) (G B18582-2001室內(nèi)裝飾裝修材料內(nèi)墻涂料中有害物質(zhì)限量、G B 50325-2001民用建筑工程室內(nèi)環(huán)境污染控制規(guī)范、HBC12-2002環(huán)境標(biāo)志產(chǎn)品認(rèn)證技術(shù)要求水性涂料 , 由于其中對(duì)VOC 值的定義不同,

2、 同樣的產(chǎn)品因采用不同的標(biāo)準(zhǔn)計(jì)算出的VOC 值相差很大, 消費(fèi)者無(wú)法從中判別那一種產(chǎn)品更有利于環(huán)保, 它們的差別體現(xiàn)在VOC 的計(jì)算公式上。例如國(guó)標(biāo)G B18582-2001及G B50325-2001對(duì)內(nèi)墻涂料VOC 的計(jì)算公式為VOC =(V -103, 此種方法的VOC 值為揮發(fā)性有機(jī)V H 2o 化合物與樣品體積的比值。而國(guó)家環(huán)保局頒布的HBC12-2002對(duì)內(nèi)墻涂料的VOC 的計(jì)算公式為( TVOC =103, 這種方( 100%-H 2O %c /w法與美國(guó)ASTM D3960-98對(duì)VOC 的定義和計(jì)算方法相同, 均為揮發(fā)性有機(jī)化合物與扣除水分后的樣品體積的比值。兩種計(jì)算方法的結(jié)

3、果相差近一倍, 以下為兩種方法計(jì)算VOC 值的比較。表1水性涂料樣品中加入不同水后各測(cè)定值的變化及VOC 值的變化試樣原樣加入10%水加入20%水揮發(fā)分/%56 圖1從表1和圖1中的數(shù)據(jù)可得出以下結(jié)論:第一, 從表1中可看出, 用HBC12-2002方法計(jì)算的VOC 值不因水分的多少而改變。而按國(guó)標(biāo)計(jì)算的VOC 值因含水量的增加而降低。第二, 如果按國(guó)家強(qiáng)制性安全標(biāo)準(zhǔn)對(duì)VOC 的限值200g/L 計(jì)算, 那么內(nèi)墻涂料中有機(jī)揮發(fā)物含量將近20%, 只比溶劑型涂料VOC 限值500g/L低60%, 這與研制水性涂料的初衷(減少對(duì)環(huán)境的污染 相悖。由此得出, 若非內(nèi)墻涂料的VOC 指標(biāo)制定的不合理,

4、 就是計(jì)算方法不合理。2不同測(cè)試方法造成VOC 的差異除上述因計(jì)算方法造成VOC 的差異外, 測(cè)定方法的不同也是造成VOC 差別的一大因素。VOC 是揮發(fā)分、密度、水分這三項(xiàng)測(cè)定結(jié)果計(jì)算得出的, 下面就不同標(biāo)準(zhǔn)對(duì)這三項(xiàng)的測(cè)定結(jié)果進(jìn)行比較。從表 2中列出的測(cè)定結(jié)果看, 揮發(fā)分(最大相對(duì)偏差1162% 、密度(最大相對(duì)偏差2102% 以不同標(biāo)準(zhǔn)測(cè)定的結(jié)果相符合, 而水分(最大相對(duì)偏差水分密度按HBC12-2002按國(guó)際計(jì)算計(jì)算VOC/g/L217217217VOC/g/L 958577中國(guó)涂料242003年第1期百家論壇18142% 的測(cè)定結(jié)果相差較大, 雖然這兩種方法都能測(cè)定水分, 但是對(duì)不同的

5、產(chǎn)品是有選擇的。G B 606-88水分測(cè)定通用方法(K arl Fischer 法 中規(guī)定了此測(cè)定方法的適用范圍, 適用于部分固體和液體有機(jī)試劑中游離水或結(jié)晶水的測(cè)定。不適用于能與卡爾費(fèi)休試劑的主要成分反應(yīng)并生成水的樣品, 以及能還原碘或氧化碘化物的樣品中水分的測(cè)定。表2測(cè)定結(jié)果執(zhí)行標(biāo)準(zhǔn)測(cè)定項(xiàng)目揮發(fā)分樣品編號(hào)W -02-014W -02-044W -02-005W -02-011W -02-004W -02-045HBC 12-2001G B 18582-2001VOC /g/L 866714862密度水分注2揮發(fā)分相對(duì)偏差/%密度相對(duì)水分相對(duì)偏差/%偏差/%注:1-表3實(shí)驗(yàn)結(jié)果樣品編號(hào)RW

6、 -02-101RW -02-103RW -02-84試樣質(zhì)量碘溶液加入量/ml 10105空白消耗硫代硫酸鈉(011015mol/l 的量/ml樣品消耗硫代硫酸鈉(011015mol/l 的量/ml樣品還原碘的量mmol/g以下三個(gè)理由, 說(shuō)明在測(cè)定VOC 時(shí)利用KarlFischer 法測(cè)水是不合理的。水性涂料中的體質(zhì)顏料如白炭黑、云母粉、高嶺土、滑石粉、膨潤(rùn)土都含有一定量的結(jié)晶水。如果涂料的配方中含有這些體質(zhì)顏料, 其結(jié)果包含了涂料中的水及這部分結(jié)晶水;表3列出的實(shí)驗(yàn)結(jié)果表明水性涂料中存在著能還原碘的物質(zhì);在用Karl Fischer 試劑滴定試樣時(shí), 試樣溶液出現(xiàn)結(jié)塊、結(jié)片現(xiàn)象, 對(duì)此

7、現(xiàn)象還找不出原因(無(wú)法做出解釋 , 在不能確定其是否影響水的測(cè)定之前應(yīng)慎重使用此法。3影響VOC 測(cè)定的因素樣品均勻性對(duì)測(cè)定VOC 準(zhǔn)確性的影響:由于水性涂料的特點(diǎn), 測(cè)定時(shí)所取試樣是否能代表涂料整體就成為影響VOC 值準(zhǔn)確性的主要因素。如何使水性涂料樣品均勻, 立邦涂料有限公司提供了如下試驗(yàn)結(jié)果:分別在5L 、1L 包裝的白色涂料中加入一定量的顏料, 用振動(dòng)混合機(jī)(型號(hào):SO -40a 0175功率/kW 混勻樣品和人工混勻樣品進(jìn)行比較。均勻程度是以下述試驗(yàn)判斷的:在1L 、5L 包裝乳膠漆中加入1%的黑色漿 , 并進(jìn)行混樣。取不m 涂布器在13cm 15cm 同時(shí)間混樣的涂料用150的白紙

8、卡上刮卡, 流平5min 后放入55的鼓風(fēng)干燥箱中干燥15min , 用CE -7000A 儀器進(jìn)行測(cè)試(光源為D65光源 。相鄰兩個(gè)時(shí)間段的涂料色差平均值相比0105則認(rèn)為混樣均勻。振動(dòng)混樣器耗時(shí)3分鐘混勻樣品, 人工耗時(shí)(5L 包裝 25分鐘、(1L 包裝 6分鐘混勻樣品。根據(jù)上述結(jié)果要求從整包裝抽取涂料樣品時(shí), 尤其是從大包裝(5L 以上的包裝 抽取樣品時(shí)要考慮上述實(shí)驗(yàn)結(jié)果的要求。如果送到檢測(cè)單位是大包裝涂料(5L 以上的包裝 實(shí)驗(yàn)人員應(yīng)考慮測(cè)試樣品的均勻性。VOC 值是否合理依據(jù)測(cè)試步驟是否合理, 也就是說(shuō)在保障樣品均一性的同時(shí), 采用合理的測(cè)試方法, 并統(tǒng)一VOC 值的計(jì)算方法, 以

9、消除因不同標(biāo)準(zhǔn)造成的VOC 值的差異。收稿日期2002-09-20中國(guó)涂料252003年第1期SUMMARIES N e w Year MessageWang Zuo (1In this new year , all enterprises should behave well than ever. Every one should make hard exercise in the management of the enterprise and do hard work to develop high-level products.The concept of the technical

10、service in coatings sales in foreign countries is introduced. the principle , connotation and resource disposition of technical ser 2vice in coatings sales are studied. We have a long way to go while conpared with coatings industry in services. how to technical service , and as a whole , the author

11、thoughts on them.Analysis on the competing status nese titanium dioxide 2An outline of and developing trend of the world dioxide industry is given. whether foreign and domestic companies may or may not invest in the industry are analyzed. Introduction on those enterprises with ten thousand tons per

12、year capacity , their developing mode , and their competing strength are made.To strengthen the strategical management is a necsssityJai Bo-ru (19So called strategical management includes the work out , the implementation and the control of the managing strategy of a enterprise. The author feels tha

13、t those entrepreneurs of domestic enterprises are lack of strategical thinkings , like to make decision at will , therefore he suggests that those entrepreneurs should put emphasis on the work out and implemen 2tation of the managing strategy and for this , one must try to establish necessary regula

14、tions.The developing trend of the marine paints for w arshipsFu Da-hai and Cao Jing-yi (10An introduction on the features of those coatings used on warships is made. focal developing directions of the marine paints for warships are bringing for 2ward.B road domain net w ork establishment in coat 2io

15、ngs sales managementHu Shu-peng and his colleagues (21The necessity and thinking of establishing this broad domain network are discussed. Technical issues which our readers may concern are introduced.Thinking aroused from a la wsult on the V OC restriction of coatings products happened in the U nite

16、d StatesHuang Tian-yuan (14Two enforceable state standards on architectural coatings products became effective last year. Strong controversy was happened because of the execution of these standards. Same thing happened in the United States. The situation became even more serious , a controversy beca

17、me a lawsuit. Which is right ? Which is wrong , this article may give us some enlighten 2ments.Several points of opinions on the measurement of the V OC of the w ater -based paintsY in Jian-wu (24Difference in VOC value may arise while you use different standard and different method of determina 2tion. By considering the feathers of the water-based paints , tests were made on the factor