郝芬 荊麗麗 杜金梅 蔣陽 許長海
摘要: 分散染料堿性染色工藝已經獲得應用和推廣,為了提供一種簡單易行的評定分散染料耐堿性能的方法,本文探討了高溫高壓染色條件下分散染料的耐堿性能。結果表明,升溫速率2 ℃/min,染色溫度130 ℃,保溫時間30 min,分別采用常規(guī)弱酸性條件(pH值約為4.8),2 g/L的CH3COONa、2 g/L的Na2CO3和2 g/L的NaOH的染浴上染滌綸織物,依據堿性條件與常規(guī)弱酸性條件染色織物的色差ΔECMC,可有效鑒定出不同分散染料的耐堿性,并根據等級劃分將分散染料分為高耐堿性(優(yōu))、一般耐堿性(良)、弱耐堿性(中)、不耐堿性(差)四級。
關鍵詞: 分散染料;耐堿性;滌綸織物;染色;評定;高溫高壓
中圖分類號: TS190.9 ? ?文獻標志碼: A ? ?文章編號: 1001-7003(2022)01-0064-05
引用頁碼: 011110DOI: 10.3969/j.issn.1001-7003.2022.01.010
滌綸織物的前處理通常在堿性浴中完成,而分散染料染色是在酸性浴中進行。前處理后的滌綸織物必須通過洗滌去除堿劑,否則染色過程中染浴pH值會產生波動,導致染色缸差、色光不正或色光變化等疵病,影響織物質量[1-2]。同時,滌綸織物在酸性浴染色時會析出低聚物,引發(fā)產品質量下降、染色設備難以清洗等一系列問題[3]。如果滌綸織物的分散染料染色能夠在堿性條件下進行,就能夠實現前處理、堿減量及分散染料染色一浴一步工藝,可有效避免酸性染色所帶來的弊端并能減少廢水排放、縮短工藝流程[4-5]。
滌綸染色常用的分散染料在堿性條件下會發(fā)生水解,染色無法順利實施。所以,滌綸堿性染色技術的關鍵是分散染料的耐堿性[6]。如果不掌握分散染料的耐堿性,而直接進行堿性條件染色,易引起染色質量問題[7-9]。由于染料結構與其耐堿性的關系尚未確定,以及缺乏分散染料的耐堿程度評判方法和堿性染色的分散染料選用標準,從而導致染整工作者選擇染料時沒有針對性。
根據印染廠滌綸堿性染色出現的實際問題,本文探索了染色工藝條件、堿劑種類及質量濃度對分散染料耐堿性的影響,并且以實驗結果為分析依據,確定了快速評估分散染料耐堿性的實驗方法,可用于堿性染色的分散染料篩選工作,有助于最大化提高工廠生產效率。
1 實 驗
1.1 材料和儀器
材料:滌綸平紋針織布(市售),平方米質量為188 g/m2。
試劑:分散紅HA-R、分散紅GS、分散黃HE-3R、分散黃BRA、分散藍H-GLW、分散藍HGL、耐堿勻染劑均為工業(yè)品(蓬萊嘉信染料化工有限公司),氫氧化鈉(NaOH)、醋酸鈉(CH3COONa)、碳酸鈉(Na2CO3)、保險粉(Na2S2O4)均為分析純(國藥集團化學試劑有限公司)。
儀器:Rapid高溫高壓小樣染色機(廈門瑞比精密機械儀器有限公司),UV2600紫外-可見分光光度儀(島津儀器蘇州有限公司),Datacolor-650反射分光光度儀(美國德塔顏色科技有限公司),pH值計STARTER 3100(奧豪斯儀器上海有限公司)。
1.2 染色工藝
采用分散紅HA-R、分散紅GS、分散黃HE-3R、分散黃BRA、分散藍H-GLW、分散藍HGL六種染料,對滌綸針織物進行染色。
1.2.1 染色處方
分散染料質量分數為1%(相對織物質量),染色溫度為115、120、125、130、135 ℃,時間為20、30、40、50、60 min,升溫速率為0.5、1、1.5、2、2.5 ℃/min,pH 4.8緩沖液為15 mL,勻染劑質量濃度為2 g/L,浴比為1 ︰ 50。
1.2.2 還原清洗處方
保險粉質量濃度為2 g/L,NaOH質量濃度為2 g/L,溫度為85 ℃,時間為20 min,浴比為1 ︰ 30。
1.2.3 工藝流程
工藝流程如圖1所示。
1.3 染色性能
使用Datacolor-650反射分光光度儀(D65光源,10°視角下)測定試樣K/S值及色差(ΔECMC)。以堿性條件染色與常規(guī)弱酸性條件(pH 4.8)染色織物的色差ΔECMC變化判斷其色變等級,分析堿性條件下分散染料的染色性能。
2 結果與分析
2.1 染色工藝優(yōu)化
2.1.1 染色溫度的影響
滌綸需要在高溫下才能上染,因此以織物的顏色深度K/S值為衡量標準,探究溫度對織物染色效果的影響。按1.2染色工藝進行滌綸染色,其中染色升溫速率2 ℃/min,保溫40 min。染色織物的K/S值如圖2所示。
由圖2可以看出,采用常規(guī)弱酸性條件染色時(pH 4.8),隨著染色溫度的升高,各支染料染色織物的K/S值會不同程度提高,而溫度達到130 ℃后,織物K/S值不再變化。這是因為滌綸無定形區(qū)分子鏈段隨著染色溫度的提高熱運動增強,形成更多可容納染料的孔隙,吸附在纖維表面的染料擴散進入孔隙完成染色,所以織物K/S值增大。但是通過分子鏈運動形成的孔隙的數量及體積受到滌綸高分子聚集態(tài)結構的限制,不會無限增大,故織物K/S值不隨染色溫度升高而無限增大,基本在130 ℃會有較好的染色效果。
2.1.2 保溫時間的影響
按1.2染色工藝,以2 ℃/min的升溫速率,130 ℃的染色保溫溫度探究保溫時間對滌綸染色性能的影響,處理后染色織物的K/S值如圖3所示。由圖3可知,隨著保溫時間的延長,分散紅HA-R、分散紅GS、分散黃HE-3R、分散黃BRA、分散藍H-GLW和分散藍HGL所得染色織物的K/S值基本不變,且保溫染色30 min后織物色深幾乎保持穩(wěn)定,說明染料在該染色時間內基本完成染色。
2.1.3 升溫速率的影響
其他染色條件不變,探究升溫速率對染色所得織物K/S值的影響,結果如圖4所示。由圖4可知,升溫速率對織物K/S值的影響規(guī)律同保溫時間對織物的影響,即升溫速率對織物K/S值的影響不大。對比六種染料在不同升溫速率下所得織物K/S值可知,大部分染料以較高的升溫速率染色仍可以獲得較穩(wěn)定的得色量,考慮到升溫速率與能源節(jié)省及勻染性之間的關系,升溫速率宜選擇2 ℃/min。
2.2 分散染料耐堿性能評價
2.2.1 分散染料對CH3COONa堿調節(jié)劑溶液的耐受性
分別將分散紅HA-R、分散紅GS、分散黃HE-3R、分散黃BRA、分散藍H-GLW、分散藍HGL按1.2染色工藝對滌綸織物進行染色,其中升溫速率為2 ℃/min,染色溫度為130 ℃,保溫時間為30 min,僅改變CH3COONa質量濃度。通過與常規(guī)弱酸性條件(pH 4.8)染色織物對比,以色差ΔECMC為衡量指標,獲取以上染料染色時對含不同質量濃度的CH3COONa堿調節(jié)劑溶液的耐受性,實驗結果如圖5所示。
當兩個染色滌綸織物樣品的色差小于1.0時,可認為兩個顏色幾乎無差別。對于同一支染料,僅改變染色酸堿性,其他參數不變,如果織物色差小于或盡可能接近1.0,則說明染料在該條件下穩(wěn)定[10]。由圖5可知,以pH值為4.8的染色滌綸織物做對照樣,除分散藍HGL外,其他染料在不同CH3COONa質量濃度下均具有小于1的色差。分散藍HGL染色時,無論CH3COONa質量濃度為多大,色差都明顯大于1,說明染料色光發(fā)生了改變,即該染料在非酸性條件下不穩(wěn)定。隨著CH3COONa質量濃度的增大,溶液pH值增大,在CH3COONa達到2 g/L時不再改變(pH 8),屬于弱堿性??梢砸源速|量濃度為染料是否耐受CH3COONa堿調節(jié)劑溶液的臨界點,作為評判染料是否屬于耐堿性的標準。據此,可認為分散藍HGL為不耐堿性染料,而分散紅HA-R、分散紅GS、分散黃HE-3R、分散黃BRA、分散藍H-GLW耐受弱堿可進一步增加染色溶液堿性以明確其耐堿程度。
2.2.2 分散染料對Na2CO3堿調節(jié)劑溶液的耐受性
將分散紅HA-R、分散紅GS、分散黃HE-3R、分散黃BRA、分散藍H-GLW按1.2染色工藝對滌綸織物進行染色,其中升溫速率為2 ℃/min,染色溫度為130 ℃,保溫時間為30 min,僅改變Na2CO3質量濃度,通過與常規(guī)弱酸性條件(pH 4.8)染色織物對比,以色差ΔECMC為衡量指標,獲取以上染料染色時對含不同質量濃度的Na2CO3堿調節(jié)劑溶液的耐受性,實驗結果如圖6所示。
由圖6可知,分散黃BRA、分散藍H-GLW染料所染織物的色差明顯大于1,分散紅HA-R、分散紅GS、分散黃HE-3R均小于1??烧J為分散黃BRA、分散藍H-GLW不耐受Na2CO3作為堿調節(jié)劑的染色,而分散紅HA-R、分散紅GS、分散黃HE-3R可耐受Na2CO3溶液的染色。由圖6還可見,不耐受Na2CO3堿調節(jié)劑溶液的染料隨Na2CO3質量濃度的增大,所得織物色差持續(xù)增大,但當Na2CO3質量濃度大于2 g/L后,色差增大幅度減小。由于2 g/L的Na2CO3溶液的pH值約為11.30,繼續(xù)增大Na2CO3質量濃度,染浴pH值基本不變,因此可以將2 g/L的Na2CO3作為染料是否耐受Na2CO3堿調節(jié)劑溶液染色的臨界點,以此作為鑒定染料是否屬于一般耐堿性。據此,可認為分散黃BRA、分散藍H-GLW屬于耐弱堿性染料,而分散紅HA-R、分散紅GS、分散黃HE-3R屬于一般耐堿性染料,可進一步增加染色溶液堿性以明確其耐堿程度。
2.2.3 分散染料對NaOH堿調節(jié)劑溶液的耐受性
將分散紅HA-R、分散紅GS、分散黃HE-3R按1.2染色工藝對滌綸織物進行染色,其中升溫速率為2 ℃/min,染色溫度為130 ℃,保溫時間為30 min,僅改變NaOH質量濃度,通過與常規(guī)弱酸性條件(pH 4.8)染色織物對比,以色差ΔECMC為衡量指標,獲取以上染料染色時對含不同質量濃度的NaOH堿調節(jié)劑溶液的耐受性,實驗結果如圖7所示。
由圖7可知,隨著NaOH質量濃度的增大,分散紅GS和分散黃HE-3R所得染色織物的色差顯著增大,且在NaOH質量濃度達到2 g/L時色差都超過了1;分散紅HA-R在NaOH質量濃度小于2 g/L時,織物色差均小于1,超過2 g/L時,織物色差ΔECMC趨向于1,但變化不明顯。因此可選2 g/L的NaOH溶液作為染料是否屬于高耐堿性的臨界點。據此,可認為分散紅GS、分散黃HE-3R屬于一般耐堿性,而分散紅HA-R為高耐堿性染料。
2.2.4 評價等級的確定
通過改變染色體系堿性,確定了評定染料耐堿性應選用的堿劑種類及質量濃度,分別為2 g/L CH3COONa、2 g/L Na2CO3、2 g/L NaOH。以染料在不同堿性條件下染色所得織物與常規(guī)弱酸性條件(pH 4.8)染色織物的色差ΔECMC為衡量指標,滿足ΔECMC≤1.0所對應的最高堿性條件為該染料的耐堿程度。分散染料按耐堿性強弱可分為優(yōu)、良、中、差四級,其中優(yōu)為高耐堿性(2 g/L NaOH條件下ΔECMC≤1.0),良為一般耐堿性(2 g/L Na2CO3條件下ΔECMC≤1.0,但2 g/L NaOH條件下ΔECMC>1.0),中為弱耐堿性(2 g/L CH3COONa條件下ΔECMC≤1.0,但2 g/L Na2CO3條件下ΔECMC>1.0),差為不耐堿性(2 g/L CH3COONa條件下ΔECMC>1.0)。分散紅HA-R、分散紅GS、分散黃HE-3R、分散黃BRA、分散藍H-GLW、分散藍HGL評價等級見表1。分散藍HGL在高溫及2 g/L CH3COONa條件下染色的滌綸織物色差ΔECMC>1,耐堿性評為差;分散黃BRA、分散藍H-GLW在2 g/L的CH3COONa條件下染色的織物色差ΔECMC<1,而在2g/L的Na2CO3條件下染色織物色差ΔECMC>1,耐堿性評為中;分散紅GS、分散黃HE-3R在2 g/L的CH3COONa、Na2CO3條件下染色的織物色差ΔECMC<1,而在2 g/L的NaOH條件下染色織物色差ΔECMC>1,耐堿性評為良;分散紅HA-R在2 g/L的CH3COONa、Na2CO3、NaOH條件下染色織物色差ΔECMC<1,耐堿性則評為優(yōu)。
3 結 論
本文探討了分散染料在不同堿性條件下對滌綸織物進行高溫高壓染色的性能,根據染色滌綸織物的色差分析了分散染料的耐堿性,得出如下結論:
1) 不同分散染料的耐堿性能差異較大。
2) 判定分散染料耐堿性能的合適實驗條件為:染色溫度130 ℃,升溫速率2 ℃/min,保溫時間30 min。
3) 分別選用2 g/L CH3COONa、2 g/L Na2CO3、2 g/L NaOH堿性條件染色,依據與常規(guī)弱酸性條件(pH 4.8)染色織物的色差ΔECMC,評價染料耐堿程度。滿足ΔECMC≤1.0所對應的最高堿性條件為該染料的耐堿程度。耐堿性強弱可分為優(yōu)、良、中、差四級,其中優(yōu)為高耐堿性,良為一般耐堿性,中為弱耐堿性,差為不耐堿性。
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[10]HUSEYIN A E, PERVIN A. Dye selections for alkaline one-step disperse/reactive dyeing of polyester/cotton blends[J]. AATCC Review, 2004, 4(7): 23-27.
Abstract: Conventionally, the pretreatment process of polyester fabric is completed in alkaline condition, but polyester fabric dyeing process is usually carried out in acidic condition. Therefore, multiple washing and acid pickling before dyeing are required to remove the residual alkali agent on the fabric, otherwise it would easily cause pH fluctuation of dyeing bath and affect the dyeing quality of fabric. In addition, due to the low solubility of the oligomer precipitated in acid bath, the dyeing fabric and dyeing equipment will be affected.
The above problems can be solved to a certain extent by using alkaline dyeing, which essentially depends on the alkali resistance of disperse dyes. However, it is difficult for dyeing and finishing workers to choose targeted dyes for alkaline dyeing because of the undetermined relationship between the dye structure and its alkali resistance, as well as the lack of alkali resistance evaluation methods for disperse dyes. To address the practical problems of alkaline dyeing of polyester fabric, we explored the impact of dyeing process conditions, types and dosages of alkali agents on the alkali resistance performance of disperse dyes and determined a simple and rapid evaluation method of the alkali resistance performance of disperse dyes with the experimental results as the analysis basis.
Firstly, we investigated the factors affecting the alkali resistance of disperse dyes under high-temperature and high-pressure conditions and chose the optimal process conditions for evaluating the alkali resistance performance of disperse dyes. K/S value was used as a measurement standard to explore the impact of temperature, heat preservation time and heating rate on the dyeing effect of polyester fabric. It was found that the K/S values of polyester fabrics were stable after dyeing at 130 ℃ for 30 minutes with a heating rate of 2 ℃/min with a dye concentration of 1% (o.w.f) and this process conditions met the requirements of alkali resistance performance test.
Secondly, we discussed the stability of disperse dyes in different alkaline solutions, and analyzed the feasibility of evaluation indexes. Disperse dyes, Red HA-R, Red GS, Yellow HE-3R, Yellow BRA, Blue H-GLW and Blue HGL were used to dye polyester fabrics under different concentrations of CH3COONa, Na2CO3 and NaOH according to above optimum dyeing process. Color difference ΔECMC between the dyed fabrics under different concentrations of different alkali agents and the dyed fabrics under conventional weak acid condition (pH 4.8) was used as a measurement index to obtain the alkali resistance of the above dyes. The results show that color differences of the 6 disperse dyes have significant differences under alkaline conditions of 2 g/L CH3COONa, 2 g/L Na2CO3, 2 g/L NaOH, respectively. ΔECMC of polyester fabrics dyed with Blue HGL disperse dye is higher than 1.00 under 2 g/L CH3COONa (pH 8.00), and ΔECMC of polyester fabrics dyed with the other five disperse dyes is all lower than 0.50 under this condition. ΔECMC of polyester fabrics dyed with Yellow BRA and Blue H-GLW disperse dyes is higher than 1.00 under 2 g/L Na2CO3 (pH 11.30), while that of Red GS Yellow HE-3R disperse dyes is higher than 1.00 only under 2 g/L NaOH (pH 12.62). ΔECMC of polyester fabrics dyed with Red HA-R disperse dye is still lower than 1.00 under 2 g/L NaOH. Therefore, alkali resistance performance of disperse dyes can be evaluated according to the color difference ΔECMC and alkaline conditions of 2 g/L CH3COONa, 2 g/L Na2CO3, 2 g/L NaOH, respectively.
Finally, the test method for evaluating the alkali resistance performance of disperse dyes was established and verified. Through dyeing under alkaline conditions of 2 g/L CH3COONa, 2 g/L Na2CO3 and 2 g/L NaOH, respectively, according to the color difference ΔECMC between the dyed fabrics and the conventional weak acid condition (pH 4.8), the alkali resistance degree of the dyes was evaluated. The highest alkaline condition meeting ΔECMC≤1.0 was determined as the alkali resistance of the dye, which can be classified in four levels: high alkali resistant (excellent), medium alkali resistant (good), weak alkali resistant (medium) and non-alkali resistant (poor). According to the established evaluation method, the alkali resistance performance of 6 disperse dyes was evaluated. The results show that Red HA-R disperse dye is evaluated as high alkali-resistant type, which can withstand dyeing with at least 2 g/L NaOH alkali regulator concentration; Red GS and Yellow HE-3R disperse dyes are medium alkali resistant; Yellow BRA and Blue H-GLW disperse dyes are weak alkali-resistant and Blue HGL is not alkali-resistant and cannot be dyed under alkaline conditions.
This evaluation method is expected to be used for evaluating the alkali resistance performance of disperse dyes with unknown evaluation structure and for the screening of disperse dyes for alkaline dyeing, and it can help maximize the production efficiency of related factories.
Key words: disperse dyes; evaluation method of alkali resistance performance; alkaline dyeing; dyeing process; polyester; alkali resistant disperse dyes