Pad-steam bleaching method for fabric based on TBLC-activated hydrogen peroxide system

Abstract

The present disclosure discloses a pad-steam bleaching method based on a TBLC-activated hydrogen peroxide system, and belongs to the field of pretreatment processing of textiles. According to the pad-steam bleaching method based on the TBLC-activated hydrogen peroxide system, TBCC and H.sub.2O.sub.2 are compounded with a weak base to prepare a TBCC/H.sub.2O.sub.2/weak base system for performing near-neutral bleaching on cotton fabrics; the fabrics are padded and then steamed to be bleached. By the method disclosed by the present disclosure, the whiteness of fabric treated for 2 minutes by a TBCC/H.sub.2O.sub.2/sodium citrate padding and steaming system is significantly superior to that of fabric treated for 60 minutes by an H.sub.2O.sub.2/NaOH dip bleaching system. The CIE whiteness of the fabric reaches 77 and above, the fabric wettability after treatment is also improved, the damage of the fabric is smaller, and the amount of water used by the method is small. The fabric only needs to have a certain wet pick-up, and a large amount of fabric can be treated by a certain volume of solution, which effectively reduces waste water treatment, saves energy and protects the environment; the method requires a short treatment time and has high bleaching efficiency.

Claims

1. A method for pad-stream bleaching of fabric, which comprises: dipping a fabric in a solution system comprising an activator N-[4-(trialkylammoniummethylene)benzoyl]lactam chloride (TBLC), H.sub.2O.sub.2, and a weak base, cold padding the fabric immediately following the dipping, steaming the fabric for 2-6 min, and washing the fabric in water, wherein the concentration of TBLC is 25-100 g/L, and the weak base is sodium citrate.

2. The method according to claim 1, wherein the structural formula of the activator TBLC (N[4-(trialkylammoniummethylene)benzoyl]lactam chloride) is as follows, wherein n is 1-5, and R.sub.1, R.sub.2 and R.sub.3 are hydrogen atoms or alkyl groups containing 1-7 carbon atoms: ##STR00003##

3. The method according to claim 1, wherein the solution system is prepared by adding the activator TBLC and H.sub.2O.sub.2 to a water solution containing a sufficient amount of sodium citrate, wherein the molar ratio of the H.sub.2O.sub.2 to TBLC is (10:1)-(1:1).

4. The method according to claim 1, wherein the molar ratio of H.sub.2O.sub.2 to TBLC is (2:1)-(1:1).

5. The method according to claim 1, wherein the solution system further comprises a stabilizer and a penetrant.

6. The method according to claim 1, wherein steaming is performed at atmospheric pressure for 2 min.

7. The method according to claim 1, wherein the fabric comprises pure or blended fabric selected from the group consisting of: (i) cotton, (ii) viscose fiber, (iii) bamboo fiber, (iv) hemp fiber, silk, wool, polyester, nylon, acrylic, polypropylene, and vinylon.

8. The method according to claim 1, wherein the mass of the fabric is 1%-100% of the mass of the solution system, and the pick-up is 10%-110%.

Description

DETAILED DESCRIPTION

(1) (1) Measurement of Whiteness

(2) The CIE whiteness index (WI) of the fabric is measured according to AATCC Test Method 110-2011. A sample is folded twice and placed on a Datacolor 650 spectrophotometer to measure the CIE whiteness of the fabric, then the sample fabric is measured again when rotated by 90 degrees for 4 times, and the results are averaged.

(3) (2) Wettability

(4) The wettability of the fabric is measured in accordance with the AATCC Test Method 79-2010 Hygroscopicity of Textiles test method. Specifically, a test sample is placed in a constant temperature and humidity chamber for 24 hours, and the parameters of the constant temperature and humidity chamber are set to, humidity: 65%, temperature: 21 C. A drop of water is dropped from a certain height onto the surface of the fabric, and the time the water droplet takes to completely disappear is recorded. The cloth surface needs to be flat. Four relatively uniform points are selected, and the recorded data is averaged. The shorter the time required for the water droplet to completely disappear is, the better the water absorbancy of the fabric is.

(5) (3) Degree of Polymerization

(6) The degree of polymerization (DP) can be used to measure the molecular weight of cotton fibers. According to the change of the degree of polymerization of the cotton fabric before and after the treatment, the damage of the fabric after the cotton fabric is treated can be judged. Generally, if the degree of polymerization of the sample after treatment is reduced as compared with the original sample, the fiber is damaged, and the higher the degree of polymerization is reduced, the more serious the damage of the fiber is.

(7) (4) Dyeing Property of Fabric

(8) The purpose of bleaching is to provide a good white matrix for subsequent dyeing and finishing. The fabric has to have good whiteness to obtain a corresponding color when the fabric is dyed into light colored fabric. The wettability of the fabric largely affects the dyeing property of the fabric. If the wettability of the fiber is poor, the speed of the dye moving from a dyeing liquid to the fabric is slow. If the wettability of the fabric is not uniform, the dye molecules on the fabric will be unevenly distributed, the color difference will be large, and dyeing will be uneven. If the fabric is subjected to large damage during the bleaching process, in the subsequent treatment, overlarge tension or chemical reagent influence may cause holes and defects in the fabric. Thus, the dyeing property of the fabric can further measure the bleaching effect of the fabric. The dyeing property can more fully reflect the treatment effect of the fabric. In this experiment, the fabrics with the same whiteness after bleaching treatment by different systems are selected, and the fabrics are placed in the same dyeing solution, and subjected to the same dyeing process. Finally, the dyeing properties of the fabrics are judged according to the color difference of the fabrics and the color characteristic values. Reactive dyes can form a covalent bond with cellulose, have good color fastness and are suitable for dyeing cotton fabrics. In this experiment, two different gray colors are prepared from the three primary color reactive dyes of Wande, and the same bath is used for competitive dyeing.

Example 1

(9) Fabric: Cotton knitted fabric (133 g/m.sup.2).

(10) Formula: TBCC, H.sub.2O.sub.2 and sodium citrate in mol ratio of 1:1.2:1.4, wherein the TBCC is 50 g/L, the stabilizer DM-1403 is 1 g/L and the penetrant JFC is 1 g/L.

(11) Pick-up: 110%.

(12) Steaming: Respectively performing treatment for 2 min, 4 min and 6 min, and measuring the fabric bleaching effects of treatment for different time.

(13) The results are as shown in table 1.

Example 2

(14) Fabric: Cotton knitted fabric (133 g/m.sup.2).

(15) Formula: TBCC, H.sub.2O.sub.2 and sodium citrate in mol ratio of 1:1.2:1.4, wherein the stabilizer DM-1403 is 1 g/L, the penetrant JFC is 1 g/L, and the TBCC is respectively 25 g/L and 75 g/L.

(16) Pick-up: 100%.

(17) Steaming time: 2 min.

(18) The results are as shown in table 1.

(19) TABLE-US-00001 TABLE 1 Bleaching Effects of Steaming for Different Time. Degree of Whiteness Polymer- Samples (CIE) ization Wettability, s Raw fabric 30.30 4152 30 4-6 Example 1, steaming for2 min 80.45 4050 52 <1 Example 1, steaming for 4 min 82.34 3942 28 <1 Example 1, steaming for 6 min 82.12 3867 31 <1 Example 2, TBCC 25 g/L 74.13 4111 22 <1 Example 2, TBCC 75 g/L 83.09 3998 28 <1 Sodium bicarbonate group 72.78 4002 22 <1 Conventional hydrogen 73.28 2365 74 <1 peroxide bleaching, 60 min

(20) In the sodium bicarbonate group, sodium citrate in Example 1 is replaced with sodium bicarbonate, steaming is performed for 2 min, and other conditions are the same as those in Example 1. As can be seen from Table 1, the whiteness of the fabric treated with the TBCC/H.sub.2O.sub.2/sodium citrate system is increased by about 12% compared with the TBCC/H.sub.2O.sub.2/NaHCO.sub.3 system.

(21) In the conventional hydrogen peroxide bleaching method, the H.sub.2O.sub.2 (30% w/v) is 6 g/L, the NaOH is 3 g/L, the penetrant JFC is 1 g/L, the stabilizer DM-1403 is 1 g/L, the temperature is 95 C., the rotation speed is 30 r/min, the bath ratio is 1:20, and treatment is performed for 10 min, 20 min, 30 min, 40 min, 50 min and 60 min. After the experiments are completed, the samples are thoroughly cleaned with a large amount of deionized water to prevent the residual surfactant from adversely affecting the subsequent performance test, and dried under natural conditions for later use; wherein the whiteness after treatment for 10 min, 20 min, 30 min, 40 min and 50 min are 55.72, 64.34, 68.91, 71.22 and 72.78, respectively.

(22) In addition, the disclosure compares the effects of different padding and steaming systems on the bleaching effects. Among them, refined fabrics (CIE whiteness is 30.30) are respectively bleached by a TBCC/H.sub.2O.sub.2/sodium citrate padding and steaming system and an H.sub.2O.sub.2/NaOH padding and steaming system. The process parameters and conditions of the two systems are shown in Table 2, and the amount of H.sub.2O.sub.2 (30%, w/v) in the two systems is always consistent. The results show that the whiteness of the fabric bleached by the H.sub.2O.sub.2/NaOH padding and steaming system is significantly higher than that before bleaching, and the whiteness increases with the steaming time. When the steaming time is prolonged to 10 minutes, the whiteness can reach 61.96, while the whiteness can reach 80.65 by steaming for 2 minutes by the TBCC/H.sub.2O.sub.2/sodium citrate padding and steaming system.

(23) TABLE-US-00002 TABLE 2 Process Formulae and Conditions of TBCC/H.sub.2O.sub.2/Sodium Citrate Padding and Steaming System and H.sub.2O.sub.2/NaOH Padding and Steaming System. Amount used TBCC/H.sub.2O.sub.2/ sodium citrate padding and H.sub.2O.sub.2/NaOH padding Reagents etc. steaming system and steaming system H.sub.2O.sub.2 (30%, w/v) (g/L) 18.4 18.4 NaOH, g/L 0 5.6 TBCC (g/L) 50 0 Sodium citrate (g/L) 56 0 Penetrant JFC (g/L) 5 Stabilizer DM--1403 (g/L) 5 Pick-up (%) 100%-110%

Example 3

(24) Fabric: Cotton knitted fabric (133 g/m.sup.2).

(25) Formula: TBCC, H.sub.2O.sub.2 and weak base in a mol ratio of 1:1.2:1.4, wherein the TBCC is 50 g/L, the stabilizer DM-1403 is 1 g/L and the penetrant JFC is 1 g/L.

(26) Pick-up: 110%.

(27) Steaming time: 2 min.

(28) The used weak bases are respectively sodium acetate, sodium carbonate, ethylamine and triethylamine.

(29) The fabric bleaching effects under different conditions are measured, and the results are shown in Table 3.

(30) TABLE-US-00003 TABLE 3 Bleaching Effects under Different Weak Bases. Weak Bases Whiteness (CIE) Sodium acetate 70.72 Sodium carbonate 70.63 Ethylamine 67.22 Triethylamine 68.29

Example 4

(31) Fabric: Regenerated bamboo viscose fiber (139 g/m.sup.2).

(32) Formula: TBCC, H.sub.2O.sub.2 and sodium citrate in a mol ratio of 1:1.2:1.4, wherein the stabilizer DM-1403 is 5 g/L, the penetrant JFC is 5 g/L, and the TBCC is respectively 25 g/L and 100 g/L.

(33) Pick-up: 100%.

(34) Steaming time: 2 min.

(35) The results are shown in table 4, wherein the conventional hydrogen peroxide bleaching method is consistent with Table 1.

(36) TABLE-US-00004 TABLE 4 Bleaching Effects under Different Treatment Conditions. Whiteness Degree of Samples (CIE) Polymerization Raw fabric 10.77 419 Bleaching according to the 64.85 380 example Conventional hydrogen 59.29 206 peroxide bleaching

(37) The disclosure described and claimed herein is not to be limited in scope by the specific aspects herein disclosed. Any person skilled in the art can make modifications without departing from the spirit and scope of the disclosure. The scope of protection of the present disclosure should therefore be defined by the claims.