A novel reactive dyestuff range with excellent color yield in Continuous and Cold Pad-Batch dyeing

Transcription

1 A novel reactive dyestuff range with excellent color yield in Continuous and Cold Pad-Batch dyeing Summary : Bao-Kun Lai, Wen-Jang Chen, Jung-Fang Yeh Everlight Chemical Industrial Corporation 6th Fl, 77, Tun Hua South Road, Sec. 2, Taipei, 106, Taiwan Since their introduction Everzol ED dyes have gained rapid and worldwide acceptance. The dyes display good build-up, economy and ECO efficiency. This article describes how these particular technical features of the Everzol ED range have been successfully applied to the cold pad-batch and Emoistfix processes, to satisfy consumers demands for higher productivity and competitiveness. The future change of textile dyeing and finishing industry On Jan 1, 2005, textile quotas were lifted. As well as the need for high quality, low cost and reliable delivery, products with quick response to customers requirements will be increasingly demanded in the printing and dyeing industry. Under pressure from rising costs in manpower, water, energy, complicated production technology and high waste water treatment, the printing and dyeing industry has invested heavily in equipment for continuous and cold pad-batch dyeing. Thus, in order survive tight environmental and competition pressures, the dyeing and printing industry has already moved partially towards the cold padbatch and Emoistfix processes, with their reduced production costs, good dyeing quality allied with high productivity and lower effluent. Demand for reactive dyes in printing and dye markets The industry has already moved largely from traditional patterns, for example time-consuming processes, to right-first time production, high reproducibility and increasingly to products and processes with environmental and ecological benefits. Ultimately the design of reactive dyes will be directed towards nontoxic, easy waste water treatment, high fixation, high color yield, easy washing off and low energy consumption. The Everzol ED ranges are designed to meet these requirements, providing a route to reduced production costs and improved ecological performance. A novel reactive dyestuffs range Everzol ED dyes were first developed by Everlight Chemical Industry Corporation in 2000 and have since gained widespread commercial acceptance. They show

2 excellent build-up, economy and Eco efficiency in customer s dyehouses. Additionally, Everzol ED dyes have been applied to pad dyeing, in order to satisfy customers demands, especially in cold pad-batch and continuous dyeing. Furthermore, Everzol Yellow ED, Everzol Yellow ED-R, Everzol Red ED, Everzol Red ED-2B and Everzol Black ED are inventions of Everlight R&D which have been patented and notified in the EU. Customers can expect to satisfy the demands of dyeing industry with excellent dyeing properties and fastness, coupled with productivity and competitiveness. In the past few years, the dyeing industry has invested heavily in equipment suitable for cold pad-batch and Emoistfix dyeing, especially in Europe and Turkey. This article will illustrate the application of Everzol ED dyes to these processes. Features of Everzol ED ranges in continuous dyeing and cold pad-batch Everzol ED dyes are suitable for continuous dyeing procedures with the main outlets, at present, being cold pad-batch, pad-dry-chemical pad-steam, pad-drybaking, etc. Meanwhile, in the light of new dyeing technology, such as the Emoistfix process, Everlight Group has further investigated Everzol ED dyes in these application processes and excellent dyeing results have been obtained. Everzol ED dyes exhibit the following features and advantages in continuous dyeing and cold pad-batch: Simple dyeing operation Same operation methods with conventional dyes used in cold pad-batch, excellent compatibility with the Everzol C range. Low cost of dyestuffs Half the usage of dyestuffs compared with conventional dyes applied in cold pad-batch. High color yield and fixation Everzol ED ranges display outstanding build-up compared with conventional dyes. Low waste after dyeing Less unfixed dye remains in the waste stream. Excellent reproducibility Consistent dyeing results under a wide variety of dyeing conditions. The application and dyeing conditions for cold pad-batch and Emoistfix process are described below: Cold pad-batch dyeing Three kinds of alkalis are recommended in the cold pad-batch method: Method A, silicate free

3 Everzol ED Dyestuff(s) 38 0 B'e NaOH 8+X/5 ml/l Glauber s salt ( Neutral salt) 30 g/l X g/l Method B, Sodium silicate Table 1: Chemical consumption with sodium silicate Everzol ED dyestuff usage Na2SiO3 <=20g/l 30g/l 40g/l 50g/l (g/l) 38 0 B'e NaOH (ml/l) 60g/l >70g/l 37~40 0 B'e ~42 0 B'e ~50 0 B'e ~60 0 B'e Method C, Sodium silicate (modified) Table 2: Chemical consumption of the sodium silicate modified method Everzol ED dyestuff usage Na2SiO3 <=10g/l 20g/l 30g/l 40g/l (g/l) 38 0 B'e NaOH (ml/l) 50g/l >60g/l 37~40 0 B'e ~42 0 B'e ~50 0 B'e ~60 0 B'e Note: The purpose of using reduced alkali is to obtain consistent stability, with respect to the dependence of pick-up rate, and batch time under high temperature. More than 16 hours of batching time is essential. Fixation procedure in cold pad-batch In this procedure dyeing is conducted at ambient temperature (preferably close to the temperature of padding liquors). The lowest fixation time must accord with the character of the dyestuff (refer to table 3). In general production, silicate-free and sodium silicate methods are recommended, with fixation times of more than 12 hours for Everzol ED. In color matching, when different dyestuffs classifications are used together, fixation time must be based on the longest fixation time of any of the dyestuffs. Table 3 lists lowest fixation times; these should not be taken as the upper limit of batching time. Consistency of shade and dyeing properties will not be affected by a longer batching time (48 hours) at ambient temperature.

4 Table 3: Lowest fixation times for Everzol C and Everzol ED dyestuffs: Shade Class I II III IV Yellow C-GL Yellow C-3RF Yellow C-3RS H/C Yellow C-4G Yellow Yellow C-GR Yellow ED-R Yellow ED Yellow C-RN Orange C-3R Red C-3BS H/C Red ED Rubine ED Red Red C-3B Red C-RB 133% Red ED-2B Red ED-3B Navy C-GG 133% Blue C-R s/p Black C-B 133% Navy C-GB H/C Blue Navy C-FB Blue C-BB 133% Navy C-BDF Navy ED Turquoise C-G 133% Blue ED Blue ED-G Black C-RL Other Black C-N 150% Black C-GSP Black ED Fixation time ~4hrs ~8hrs ~12hrs ~16hrs If the fixation temperature is reduced, the minimum fixation time must be lengthened. If the fixation temperature is much higher than ambient temperature, the modified sodium silicate method is recommended and the batching time is more than16 hours. The longest batching time should not exceed 24 hours if method A or method B are adopted at higher batching temperature. Emoistfix dyeing process The development of the Emoistfix process. The purpose of the Emoistfix dyeing process is to reduce the consumption of chemicals such as urea and alkali. The Emoistfix dyeing process is costeffectiveness, simple, easy to operate, energy and labour efficient, ecologically attractive and provides easy control in continuous dyeing. The Emoistfix dyeing process comprises of a passage of fabric through the padding liquor, followed by oven drying and wet treatment, by steam. Fabrics are passed through a padding liquor that contains both dyestuffs and alkali, followed by the dyestuff migration, drying and fixation, steam. The Emoistfix dyeing process is one step. In exhaustion dyeing, dyestuffs are adsorbed and desorbed simultaneously repeatedly. However the Emoistfix process yields high fixation and allows control of dye migration to give level dyeings.

5 Conditions for Everzol ED application in the Emoistfix dyeing process Everzol ED Dyestuffs X g/l Penetration (or wetting) agent 0-2g/l Reduction inhibitor 5-10g/l Migration inhibitor 0-1g/l Urea (optional) 0-25g/l Neutral salt and alkali See table 4 Table 4: Alkali demand in Emoistfix process The amount of dye g/l < 20 20~40 40~60 60~80 80~100 > B'e NaOH ml/l Na 2 CO 3 g/l 20 Salt g/l 0-30 Padding liquor temperature: 20-25, Mixing pump is recommended. Fixation procedure of Emoistfix process: Padded fabrics are dried for 2-3 minutes at 120~130 with humidity at 25-30%. Continuous washing procedure In reactive dyeing, the efficiency of the washing off process is vital to the fastness properties of dyed fabrics, thus any unfixed dye must be thoroughly removed. The use of hot water in sufficient amounts, is the key to any efficient washing process. Furthermore the use of sufficient water, with an overflow system, to dilute the concentration of unfixed dyestuff improves washing off. A soaping process at 90~95, consequently yields excellent results. The general continuous washing procedure is described as follows a. Cold rinsing (with overflow) one tank 30~40 b. Warm rinsing one tank 50~60 (or neutralizing, alkali without sodium silicate) c. Hot rinsing two tanks 90~95 d. Soaping two tanks 90~95 e. Warm rinsing one tank 50~60 f. Cold rinsing one tank 30~40 (Neutralization, ph value set at 6~7)

6 Dyeing Behavior of Everzol ED dyes in cold Pad-Batch Everzol ED dyes achieve superior fastness properties in the cold pad-batch process due to a combination of advantages. Medium Substantivity Evrezol ED dyes are especially designed to be of medium substantivity and provide adequate levelling and non-tailing (prevent tailing effectively). Figure 1: Influence of Colour Strength upon Tailing 110% Relative colour strength (%) 105% 100% 95% Formulation-1 Formulation-2 90% 0% 10% 20% 30% 40% 50% Consumption of dyeing liquor (%) Consumption of dyeing liquor (%) Beginning 10% 25% 35% 50% Formulation-1 100% 99.9% 99.9% 99.9% 99.4% Formulation-2 100% 99.8% 99.5% 99.4% 99.1% Formulation-1 Formulation-2 Everzol Yellow ED 10g/l Everzol Yellow ED 20g/l Everzol Red ED 10g/l Everzol Red ED 20g/l Everzol Blue ED 10g/l Everzol Blue ED 20g/l Alkali Alkali

7 Sodium Silicate (48 o B e) 100g/l Sodium Silicate (48 o B e) 100g/l NaOH(38 o B e) 20ml/l NaOH(38 o B e) 25ml/l Dyeing method : Cold pad-batch process Substrate : Mercerized cotton Dyeing temperature : 25 o C Batching time : 16 hours According to Figure 1, which depicts the influence of colour strength upon tailing, the colour strength of Everzol ED dyes stay stable during the consumption of dyeing liquor. For achieving stable dyeing quality, the addition of dyeing liquor is suggested allowing continuous exchanging in order to achieve dynamic balance. Colour Strength and Fixation Everzol ED dyes are cost-effective with extremely high colour strength, excellent reproducibility, and with full and very easy wash off of unfixed dye. This special design allows minimum consumption of water and energy, thus not only decreasing the amount of wasted water but also any adverse effects on the environment. Moreover, Everzol ED dyes achieve the same colour strength with lower amounts of dye (Table 5). Table 5: Consumption of dyes and chemical to reveal the same colour strength Dye composition Dye Consumption (g/l) Alkali Combination Sodium silicate Yellow Red Navy Yellow Red Navy (48 o B e) + NaOH(38 o B e) Dyeing Concentration (g/l) Difference of Consumption Everzol ED Y-ED R-ED N-ED g/l + 15ml/l 30 standard Reactive Y-206 R-228 B g/l + 20ml/l % Reactive Or-107 R-198 B g/l + 20ml/l % Reactive Y-145 R-195 B g/l + 25ml/l % Matching shade : Pantone TC. Dyeing method : Cold pad-batch process Batching Condition : 25 o C for 16 hours Combinations of Everzol ED dyes, in accordance with Table 5, show high fixation

8 and excellent washing fastness as follows. (a) Fixation test By measuring the optical absorbance of the dyebath before dyeing and the total effluent (unfixed dyes with washing process) of Everzol ED dyes, it is possible to calculate the fixation by the formula Fixation(% ) = A(Absorbance before dyeing)- B(Absorbance of effluent) A(Absorbance before dyeing) x 100% Washing process: (1)40 o C for 2 minute Cold rinsing (2)60 o C for 2 minute Warm rinsing (3)95 o C for 2 minute Hot rinsing (4)95 o C for 2 minute Hot rinsing (5)95 o C for 2 minute Soaping (6)95 o C for 2 minute Soaping (7)60 o C for 2 minute Warm rinsing (8)40 o C for 2 minute Cold rinsing The absorbance of the wash liquor for each step of the washing process is listed in Table 6. Table 6:The absorbance of liquor before dyeing and effluent Washing Process Total Before dyeing Effluent Fixation(% ) = x 100% = 91.23% (b) Washing test The absorbance of effluent (unfixed dyes for each step of washing process) of Everzol ED dyes is measured. The percentage of unfixed dye removed at any washing stage is given by the formula below. For example % unfixed dye removed during washing steps 1 to 4.

9 Washing property(%) = Sum of effluent absorbance for steps one to four Total effluent absorbance for eight steps According to Table 6: The sum of effluent absorbance for steps one to four = =765.5 x 100% Total effluent absorbance for eight steps = Washing property(%) = x 100% = 91.0% i.e. 91% of unfixed dye removed during washing steps 1 to 4. Dye reproducibility and compatibility Everzol ED dyes, Everzol C dyes and some of the Everzol dyes are highly compatible and have superior reproducibility in continuous processes, the Emoistfix process and cold pad-batch processing. Combinations of dyes and their suitability for different dyeing processes are listed in Table 8. <Table 8> Combinations of dyes and their suitability for different dyeing processes Dyeing Process Yellow ED-2G Yellow ED-R Yellow ED Orange ED-2R Red ED Red ED-2B Red ED-3B Cold pad-batch Pad-Dry-Pad-Steam Pad-Dry- Baking Pad-Steam Emoistfix Dyeing Process Rubine ED Blue ED Blue ED-G Navy ED Black ED Black ED-2R Cold-pad batch Pad-Dry-Pad-Steam Pad-Dry- Baking Pad-Steam Emoistfix Meaning of symbols : : suitble : selective usage : not recommend

10 Dyeing fastness and dependency on process stability Everzol ED dyes have good alkali-solubility and alkali liquor stability which allows high fastness and reproducibility. During the cold pad-batch process, dyeing liquor is at high ph after the addition of alkali. Even under high ph, excellent dye liquor stability ensures the quality of the dyeing process as demonstrated in Figure 2, with Everzol Black ED. During the pad-dry-pad-steam process, Everzol ED dyes are not susceptible to hydrolysis, limiting the impact of pad-steam time variation on dyeing results (Figure 3). Figure 2: Dyeing liquor stability 110 Colour Strength (%) oC 35oC Time (minute) Colour Time (minutes) strength (%)

11 25 o C o C Dyeing Method : Cold pad-batch process Dye : Everzol Black ED 60g/l Substrate : Mercerized cotton Dyeing temperature : 25 o C Rolling Time : 16 hours Alkali : Sodium Silicate(48 o B e) 100g/l NaOH(38 o B e) 20ml/l Figure 3: Dependency on pad-steam time variation

12 120 Colour Strength (%) Alkali-A Alkali-B Time (second) Colour Time (seconds) strength (%) Alkali-A Alkali-B Dyeing Method : Pad-dry-Pad-steam process Dye : Everzol Black ED 60g/l Substrate : Mercerized cotton Alkali : Alkali-A NaOH(38 o B e) 20ml/l Na 2 SO 4 250g/l Alkali-B Sodium Silicate(48 o B e) 70% NaOH(38 o B e) 20ml/l Steaming : Saturated steam at 102 o C Dyes fastness properties Everzol ED dyes have superior solubility in water and alkali and readily provide desired levels of fastness.

13 Table 9: Dyes fastness properties fastness Solubility Alkali-solubility NaOH + Na 2 SO 4 NaOH + Sodium Silicate Washing-off ISO 105 C02 Perspiration ISO 105 E04 Color change CO PA Color change CO PA Color change Rubbing 105 X 12 CO PA Dry Wet Light ISO 105 B02 (blue scale) Everzol ED Yellow ED-R >6 Yellow ED >6 Red ED Red ED-2B Red ED-3B Rubine ED Blue ED-G >6 Blue ED Navy ED Black ED Note : Dyeing concentration for all dyes is 30g/l except Everzol Black ED 60g/l. Conclusion Developments in the printing industry have promoted the development of new dyestuffs, as well as technical processes. Business survival depends on environmental protection and social responsibility, demanded of businesses, consumer consciousness and government policy. Everzol ED dyes are designed to meet these requirements and provide optimised environmentally-efficient products. The changing pattern of global textile demand has aided the cooperation between the printing and dyestuff industries. The R&D, technical service and marketing groups of Everlight are always concerned about the demand of the Printing Industry and are continually researching and developing high quality dyestuffs and sharing the latest information and technical service with customers. Though Everzol ED dyes achieve the level of fastness required by both exhaust and pad batch customers, Everlight will extend the next generation of Everzol ED dyes to include the printing business.