TWI752829B - Decolorization method for dyed fiber cloth - Google Patents

Abstract

A decolorization method for a dyed fiber cloth is provided. The decolorization method for the dyed fiber cloth includes steps of: providing a fiber cloth attached with a dye; extracting the dye on the fiber cloth by an extractant; and applying microwave to evaporate the extractant so as to obtain a dry and discolored fiber cloth. The application of microwave can decrease a loss of the extractant and improve a recovery rate of the extractant.

Description

Decolorization method of fiber cloth

The invention relates to a method for decolorizing fiber cloth, in particular to a method for decolorizing fiber cloth which can effectively recover extraction solvent.

Due to the rising awareness of environmental protection, how to recycle industrial and household waste has become an important topic and business opportunity today. Among the many recyclable products, fiber cloth obviously occupies a place. In the recycling process of fiber cloth, how to effectively remove the dye is an important issue. If the dye cannot be completely removed, the fiber cloth will not be able to carry out subsequent purification treatment.

In order to remove dyes from fiber cloth, extraction solvent is generally added for extraction. The prior art also provides many documents on how to improve the extraction effect, such as selecting a specific solvent or matching a specific extraction method.

In the decolorization process of the whole fiber cloth, the extraction effect of the extraction solvent on the dye is of course important, but in terms of environmental protection concept, how to improve the recovery rate of the extraction solvent and how to reduce the emission of the extraction solvent is also very important. If the extraction solvent is discharged arbitrarily, it will inevitably cause pollution to the environment, but it will go against the original intention of sustainable operation. Therefore, the present invention is devoted to improving the recovery rate of the extraction solvent, and proposes a corresponding improvement method, so that not only the burden on the environment can be reduced, but also the use cost of the extraction solvent can be reduced.

In the traditional fiber cloth decolorization method, after the extraction step is completed, the fiber cloth is mostly dried by hot-air drying or vacuum drying. Extract the gas to recover the extraction solvent. Whether it is hot air drying or vacuum drying, the remaining solvent is taken away by the gas medium to achieve the effect of drying the fiber cloth. However, the extraction solvent is easily lost in the whole drying process, so that the recovery rate of the extraction solvent cannot be effectively improved. Generally speaking, the recovery rate of the extraction solvent in the decolorization method of traditional fiber cloth is at most 80%.

The technical problem to be solved by the present invention is to provide a decolorization method for fiber cloth in view of the deficiencies of the prior art.

In order to solve the above-mentioned technical problems, one of the technical solutions adopted by the present invention is to provide a decolorization method of fiber cloth. The decolorization method of fiber cloth includes the following steps: providing a fiber cloth with a dye attached; using an extraction solvent to extract the dye on the fiber cloth; applying microwaves to vaporize the extraction solvent, and obtaining a dry and processed Decolorized fiber cloth.

In some embodiments of the present invention, the extraction solvent is extracted at a temperature of 70°C to 130°C.

In some embodiments of the present invention, a portion of the extraction solvent is separated by filtration prior to application of the microwaves.

In some embodiments of the present invention, after filtering to separate the part of the extraction solvent, the total weight of the fiber cloth and the extraction solvent remaining on the fiber cloth is 100 weight percent, the 5 to 70 weight percent of the extraction solvent remains on the fiber cloth.

In some embodiments of the present invention, the total weight of the fiber cloth and the extraction solvent remaining on the fiber cloth is 100% by weight, and 0% to 5% by weight of all remaining on the fiber cloth the extraction solvent.

In some embodiments of the present invention, the extraction solvent after vaporization is collected and condensed, and the recovery rate of the extraction solvent is over 90%.

In some embodiments of the present invention, the weight ratio of the extraction solvent to the fiber cloth is 10 to 30.

In some embodiments of the present invention, in the step of applying microwaves, the heat transfer direction and the mass transfer direction of the extraction solvent are the same.

In some embodiments of the present invention, after the microwave is applied, the temperature of the fiber cloth is greater than the boiling point of the extraction solvent.

In some embodiments of the present invention, using the extraction solvent, the dye on the fiber cloth is extracted 1 to 6 times.

One of the beneficial effects of the present invention is that the decolorization method for fiber cloth provided by the present invention can reduce the loss of the extraction solvent and improve the recovery of the extraction solvent through the technical solution of "applying microwaves to vaporize the extraction solvent" Rate.

For a further understanding of the features and technical content of the present invention, please refer to the following detailed descriptions and drawings of the present invention. However, the drawings provided are only for reference and description, and are not intended to limit the present invention.

The following are specific specific examples to illustrate the embodiments of the "decolorization method for fiber cloth" disclosed in the present invention, and those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of the present invention. In addition, the drawings of the present invention are merely schematic illustrations, and are not drawn according to the actual size, and are stated in advance. The following embodiments will further describe the related technical contents of the present invention in detail, but the disclosed contents are not intended to limit the protection scope of the present invention. In addition, the term "or", as used herein, should include any one or a combination of more of the associated listed items, as the case may be.

In order to overcome the problem that the solvent is not easy to recover in the prior art, the present invention provides a method for decolorizing fiber cloth, which mainly includes providing dyed fiber cloth (step S1), extracting dyes on the fiber cloth (step S2), and drying the fiber cloth (Steps S3, S4) Three parts.

It is worth noting that, in the part of drying the fiber cloth, the present invention applies energy (for example: microwave) to the fiber cloth to directly heat the fiber cloth and achieve the drying effect, rather than through other heat sources (for example: hot air), to indirectly heat the fiber cloth.

When the temperature of the fiber cloth is higher than the boiling point of the extraction solvent, the entrained or residual extraction solvent in the fiber cloth will vaporize. Therefore, the vaporized extraction solvent can be collected and condensed to achieve the effect of recovering the extraction solvent. Since the present invention does not use other gaseous medium to heat the fiber cloth, the concentration of the extraction solvent will not be diluted by the gaseous medium, and high-concentration extraction solvent gas can be directly collected, thereby reducing the risk of the extraction solvent escaping.

Referring to FIG. 1 , the present invention provides a method for decolorizing fiber cloth, which includes the following steps: providing a dyed fiber cloth (step S1 ); using an extraction solvent to extract dyes on the fiber cloth (step S2 ) ; separate a part of the extraction solvent by filtration (step S3 ); and apply microwaves in a closed tank to vaporize another part of the extraction solvent and obtain a dry and decolorized fiber cloth (step S4 ). The fiber cloth decolorization method of the invention can not only decolorize the fiber cloth, but also recover more than 90% of the extraction solvent, so as to avoid environmental pollution caused by the extraction solvent.

In step S1, the dyed fiber cloth is a fiber cloth with a dye attached.

The fiber cloth can be a fiber cloth made of polyester material, and the polyester material can be polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate ester (PBT) or polyarylate (PAR). In addition, the polyester material can also be mixed with other components, such as cotton and nylon, but the present invention is not limited thereto.

In step S2, an extraction solvent is used to extract the dyes on the fiber cloth. The mixing method of the extraction solvent and the fiber cloth is not limited, as long as the extraction effect can be achieved, it is within the protection scope of the present invention.

In some embodiments, the extraction solvent is directly contacted with the fiber cloth in a liquid state to extract the dyes in the fiber cloth. Specifically, the extraction solvent and the fibers can be arranged in a decolorizing tank, and the extraction solvent can be continuously contacted with the fiber cloth through continuous stirring and mixing, thereby achieving the effect of extracting the dyes in the fiber cloth. In this operation mode, the concentration of dye in the extraction solvent will gradually increase with time. When the concentration of dye in the extraction solvent reaches saturation, the extraction effect of the extraction solvent will decrease, and the problem of back-staining may occur. Therefore, in the process of extraction, it is necessary to add clean extraction solvent.

In other embodiments, the extraction solvent first contacts the fiber cloth in a gaseous state, and extracts the dyes in the fiber cloth. Specifically, the extraction solvent is first heated to form an extraction vapor, and then the extraction vapor is contacted with the fiber cloth to extract the dyes in the fiber cloth. In this operation mode, high-purity extraction steam is used to contact the fiber cloth, so the extraction effect is not limited by the concentration of the dye in the extraction solvent, and there is no problem of back dyeing.

The present invention also further controls extraction temperature to be 70 DEG C to 130 DEG C, preferably, extraction temperature is 110 DEG C to 130 DEG C, extracts during above-mentioned temperature range, can have better extraction effect. In addition, the fiber cloth can be extracted for 1 to 6 times to completely decolorize the fiber cloth, and a fiber cloth with a whiteness (L value) greater than 75 can be obtained.

In some embodiments, the weight ratio of extraction solvent to fiber cloth is 10 to 30. If the content of the extraction solvent is too low, a longer extraction time is required, and new extraction solvent needs to be continuously replenished, which is not conducive to the progress of the process. If the content of the extraction solvent is too high, a large amount of extraction solvent containing dyes needs to be processed in subsequent steps, which will increase the cost.

In some embodiments, the extraction solvent can be selected according to the material of the fiber cloth and the type of dye, for example, the extraction solvent can be selected from the group consisting of: ethylene glycol monomethyl ether (EM, boiling point 124°) C), diethylene glycol monomethyl ether (DEM, boiling point 194°C), triethylene glycol monomethyl ether (TEM, boiling point 122°C/10mmHg), ethylene glycol monoethyl ether (EE, boiling point 135.6°C) , Diethylene glycol monoethyl ether (DE, boiling point 201.9°C), ethylene glycol monobutyl ether (EB, boiling point 171°C), ethylene glycol propyl ether (EP, boiling point 151.3°C), propylene glycol monomethyl ether ( PM, bp 120°C), dipropylene glycol monomethyl ether (DPM, bp 190°C), propylene glycol monoethyl ether (PE, bp 132.8°C), dipropylene glycol monoethyl ether (DPE, bp 223.5°C), propylene glycol monobutyl ether Ether (PNB, bp 171.1°C), dipropylene glycol monobutyl ether (DPNB, bp 222°C), propylene glycol propyl ether (PP, bp 149°C) and dipropylene glycol propyl ether (DPP, bp 243°C). However, the present invention is not limited to this.

Preferably, the extraction solvent is one or more of ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether or propylene glycol monoethyl ether. In a preferred embodiment, the extraction solvent is propylene glycol monomethyl ether. When propylene glycol monomethyl ether is used to extract the fiber cloth of polyester material, it can have a better extraction effect.

In the part of drying the fiber cloth, the present invention will firstly separate a part of the extraction solvent by means of filtration (step S3 ), and then separate the remaining extraction solvent by means of microwave heating (step S4 ). In this way, the time spent on the overall recovery can be saved and an excellent recovery of extraction solvent can be achieved. It should be noted that step S3 is an optional step, and it can be determined whether to omit step S3 according to the actual operation process.

In some embodiments, when the extraction solvent is directly in contact with the fiber cloth in a liquid state for extraction, a filtration step (step S3 ) is usually performed to separate a part of the extraction solvent, and then microwaves are applied to completely dry the fibers cloth (step S4) to reduce the energy consumption of applying microwaves.

In other embodiments, when the extraction solvent is first contacted with the fiber cloth in a gaseous state, and then condensed on the fiber cloth to extract the dyes in the fiber cloth, it is not necessary to go through the step of filtering (step S3) first, but it can be Microwaves are directly applied to completely dry the fiber cloth (step S4).

In step S3, a part of the extraction solvent is separated by filtration. In some embodiments, a filter screen with a pore size of less than 1 cm is used to separate the solid fiber cloth and the liquid extraction solvent by means of gravity filtration. In other embodiments, centrifugal filtration can also be used to separate the fiber cloth and the extraction solvent, but the present invention is not limited to this.

After the filtration step (step S3 ), the total weight of the fiber cloth and the extraction solvent remaining on the fiber cloth is 100 weight percent (wt %), and 5 to 70 weight percent of the extraction solvent remains on the fiber cloth. In a preferred embodiment, 5 to 60 weight percent of the extraction solvent remains on the fiber cloth.

In step S4, microwaves are applied in a closed tank to vaporize another part of the extraction solvent, and a dry and decolorized fiber cloth is obtained. After the drying step (step S4), the total weight of the fiber cloth and the extraction solvent remaining on the fiber cloth is 100% by weight, and 0% to 5% by weight of the extraction solvent remains on the fiber cloth.

The invention selects the method of applying microwave to heat the fiber cloth and the extraction solvent, which can not only dry the fiber cloth, but also improve the recovery rate of the extraction solvent.

The present invention uses microwave heating to achieve the effect of heating the fiber cloth and the extraction solvent without passing through other media. Specifically, after absorbing microwaves, the extraction solvent can directly convert electromagnetic energy into thermal energy. After the thermal energy is stored, the temperature of the extraction solvent will gradually increase. Once the boiling point of the extraction solvent is reached, the extraction solvent will vaporize to form a gas, which will react with the extraction solvent. The fiber cloth is separated to achieve the effect of drying the fiber cloth.

Due to the method of applying microwave to dry the fiber cloth, energy does not need to be transmitted through other gaseous media (such as hot air), so the loss of energy during transmission can be reduced, and better drying efficiency can be achieved.

In addition, when collecting the vaporized extraction solvent, since the use of the gas medium is excluded, the vaporized extraction solvent is less likely to be lost in the process of entrainment by the gas medium, thereby improving the problem of low recovery rate of the extraction solvent in the past.

Microscopically, through the operation of applying microwaves, the temperature of the extraction solvent itself will increase and be higher than the surrounding environment, so the direction of heat transfer is outward. When the extraction solvent is vaporized, the mass transfer direction of the extraction vapor is also outward. That is, for the extraction solvent, the direction of heat transfer is the same as that of mass transfer. In this way, the operation of applying microwaves can accelerate the rate of drying, and the use of heat transfer media can be omitted.

In contrast, the traditional method of drying the fiber cloth with hot air and introducing hot air can also heat the extraction solvent to increase its temperature, but for the extraction solvent, the direction of heat transfer is inward. When the temperature of the extraction solvent increases, it will vaporize to form a gas, so the mass transfer direction of the extraction vapor is outward. That is, for the extraction solvent, the direction of heat transfer is opposite to that of mass transfer.

In this embodiment, the power supplied by the microwave is 50 W to 500 W, and preferably, the power supplied by the microwave is 100 W to 400 W. In this embodiment, the time for applying the microwave is 5 minutes to 30 minutes, preferably, the time for applying the microwave is 10 minutes to 30 minutes. But it is not limited to this, and the time for applying the microwave can be adjusted correspondingly according to the power supplied by the microwave.

In this embodiment, after the microwave is applied, the temperature of the fiber cloth is higher than the boiling point of the extraction solvent. Specifically, after applying the microwave, the temperature of the fiber cloth is 130°C to 160°C. Preferably, after the microwave is applied, the temperature of the fiber cloth is 140°C to 150°C.

[Extraction solvent recovery rate test]

In order to prove that the method of applying microwaves in the present invention has the effect of improving the recovery rate of the extraction solvent, please refer to the following Examples 1 to 8 and Comparative Examples 1 to 4.

[Examples 1 to 4]

100 grams of PET fiber cloth and 1500 grams of propylene glycol monomethyl ether (extraction solvent) were placed in a flask, and the mixture was stirred at a temperature of 120 ° C for 1 hour for extraction to extract the dyes in the PET fiber cloth. Next, the propylene glycol monomethyl ether and the PET fiber cloth were separated by filtration. And repeat the aforementioned extraction and filtration steps 2 times to completely remove the dye.

After the filtration step (step S3), the PET fiber cloth is weighed, and the residual amount of the extraction solvent on the PET fiber cloth is calculated. The weight of the PET fiber cloth after filtration and the residual amount of the extraction solvent in Examples 1 to 4 are listed in Table 1. As can be seen from Table 1, 25 to 150 grams of propylene glycol monomethyl ether remained on the PET fiber cloth. That is to say, after the filtering step, the total weight of the PET fiber cloth and the residual propylene glycol monomethyl ether on the PET fiber cloth is 100 weight percent, and the residual amount of the extraction solvent of the PET fiber cloth is 20 weight percent to 60 weight percent.

Next, microwaves were applied at a power of 300W, and the surface of the PET fiber cloth was maintained at a temperature of 145 ° C for 20 minutes to vaporize propylene glycol monomethyl ether to dry the PET fiber cloth and obtain a dry and decolorized fiber The whiteness (L value) of the dry and decolorized fiber cloth is greater than 75%.

After the drying step (step S4), the PET fiber cloth is weighed, and the residual amount of the extraction solvent on the PET fiber cloth is calculated. The weight of the dried PET fiber cloth and the residual amount of the extraction solvent in Examples 1 to 4 are listed in Table 1.

The propylene glycol monomethyl ether of vaporization is collected by condenser condensation, after the condensate is cooled to 25 DEG C, measure the weight of the extraction solvent that collects, and can calculate the amount of the extraction solvent lost in the vaporization and condensation process. Loss of extraction solvent after drying = (residual amount of extraction solvent after filtration - residual amount of extraction solvent after drying - amount of condensation of extraction solvent after drying). In Examples 1 to 4, the condensed amount of the extraction solvent and the amount of extraction solvent lost in the dried PET fiber cloth are listed in Table 1.

Finally, in order to prove that the method of applying microwaves in the present invention can improve the recovery rate of the extraction solvent, the recovery rate of the extraction solvent is calculated according to the following formula: the condensation amount of the extraction solvent after drying/the residual amount of the extraction solvent after filtration×100%. The extraction solvent recoveries for Examples 1 to 4 are listed in Table 1.

Table 1 Example 1 Example 2 Example 3 Example 4 Net weight of fiber cloth (g) 100 100 100 100 After S3 step Total weight of fiber cloth (g) 125 142.9 166.7 250 Residual amount of extraction solvent (g) 25 42.9 66.7 150 Extraction solvent residue (wt%) 20 30 40 60 After S4 step Total weight of fiber cloth (g) 100.2 100.4 101.1 101.5 Residual amount of extraction solvent (g) 0.2 0.4 1.1 1.5 Extraction solvent residue (wt%) 0.2 0.4 1.1 1.5 Extraction solvent condensation amount (g) 24.7 42.3 65.2 148.0 Extraction solvent loss (g) 0.1 0.2 0.4 0.5 Extraction solvent recovery rate (%) 98.8 98.6 97.8 98.7

[Examples 5 to 8]

Examples 5 to 8 are similar to Examples 1 to 4, the main difference is that in Examples 5 to 8, in the drying step (step S4), the surface of the PET fiber cloth was maintained at a temperature of 145°C for 10 minutes.

100 grams of PET fiber cloth and 1500 grams of propylene glycol monomethyl ether (extraction solvent) were placed in a flask, and the mixture was stirred at a temperature of 120 ° C for 1 hour for extraction to extract the dyes in the PET fiber cloth. Next, the propylene glycol monomethyl ether and the PET fiber cloth were separated by filtration. And repeat the aforementioned extraction and filtration steps 2 times to completely remove the dye.

After the filtration step (step S3), the PET fiber cloth is weighed, and the residual amount of the extraction solvent on the PET fiber cloth is calculated. The weight of the PET fiber cloth after filtration and the residual amount of the extraction solvent in Examples 5 to 8 are listed in Table 2. As can be seen from Table 2, 25 to 150 grams of propylene glycol monomethyl ether remained on the PET fiber cloth. That is to say, after the filtering step, the total weight of the PET fiber cloth and the residual propylene glycol monomethyl ether on the PET fiber cloth is 100 weight percent, and the residual amount of the extraction solvent of the PET fiber cloth is 20 weight percent to 60 weight percent.

Next, microwaves were applied at a power of 300W, and the surface of the PET fiber cloth was maintained at a temperature of 145 ° C for 10 minutes to vaporize propylene glycol monomethyl ether to dry the PET fiber cloth and obtain a dry and decolorized fiber The whiteness (L value) of the dry and decolorized fiber cloth is greater than 75%.

After the drying step (step S4), the PET fiber cloth is weighed, and the residual amount of the extraction solvent on the PET fiber cloth is calculated. The weight of the dried PET fiber cloth and the residual amount of the extraction solvent in Examples 5 to 8 are listed in Table 2.

The propylene glycol monomethyl ether of vaporization is collected by condenser condensation, after the condensate is cooled to 25 DEG C, measure the weight of the extraction solvent that collects, and can calculate the amount of the extraction solvent lost in the vaporization and condensation process. Loss of extraction solvent after drying = (residual amount of extraction solvent after filtration - residual amount of extraction solvent after drying - amount of condensation of extraction solvent after drying). In Examples 5 to 8, the condensed amount of extraction solvent and the amount of extraction solvent lost in the dried PET fiber cloth are listed in Table 2.

Finally, in order to prove that the method of applying microwaves in the present invention can improve the recovery rate of the extraction solvent, the recovery rate of the extraction solvent is calculated according to the following formula: the condensation amount of the extraction solvent after drying/the residual amount of the extraction solvent after filtration×100%. The extraction solvent recoveries for Examples 5 to 8 are listed in Table 2.

Table 2 Example 5 Example 6 Example 7 Example 8 Net weight of fiber cloth (g) 100 100 100 100 After S3 step Total weight of fiber cloth (g) 125 142.9 166.7 250 Residual amount of extraction solvent (g) 25 42.9 66.7 150 Extraction solvent residue (wt%) 20 30 40 60 After S4 step Total weight of fiber cloth (g) 100.4 100.8 102.2 103.6 Residual amount of extraction solvent (g) 0.4 0.8 2.2 3.6 Extraction solvent residue (wt%) 0.4 0.8 2.2 3.5 Extraction solvent condensation amount (g) 24.5 42.0 64.1 146.0 Extraction solvent loss (g) 0.1 0.1 0.4 0.4 Extraction solvent recovery rate (%) 98.0 97.9 96.1 97.3

From the results in Table 1 and Table 2, it can be known that the method of applying microwave to vaporize the extraction solvent can greatly reduce the loss of the extraction solvent, thereby improving the recovery rate of the extraction solvent. Specifically, after the drying step (step S4 ), the loss of the extraction solvent is less than 1 g, preferably, the loss of the extraction solvent is less than 0.5 g. Moreover, the recovery rate of the extraction solvent is more than 90%, preferably, the recovery rate of the extraction solvent is more than 95%, and more preferably, the recovery rate of the extraction solvent is more than 96%.

After the filtration step (step S3 ), the smaller the residual amount of the extraction solvent, the smaller the residual amount of the extraction solvent after the drying step (step S4 ). Specifically, controlling the residual amount of the extraction solvent on the fiber cloth after the filtration step (step S3) to be 20% to 60% by weight can reduce the residual amount of the extraction solvent on the fiber cloth after the drying step (step S4) to 0% by weight to 5 weight percent.

[Comparative Examples 1 to 4]

Comparative Examples 1 to 4 are similar to Examples 1 to 4, and the main difference is that in Comparative Examples 1 to 4, the PET fiber cloth is dried by hot air, rather than microwaves.

In Comparative Examples 1 to 4, 100 g of PET fiber cloth and 1500 g of propylene glycol monomethyl ether (extraction solvent) were placed in a flask, and were stirred for 1 hour at a temperature of 120° C. for extraction to extract the PET fiber cloth dyes in. Next, the propylene glycol monomethyl ether and the PET fiber cloth were separated by filtration. And repeat the aforementioned extraction and filtration steps 2 times to completely remove the dye.

After the filtration step, the PET fiber cloth was weighed, and the residual amount of the extraction solvent on the PET fiber cloth was calculated. The weight of the PET fiber cloth after filtration and the residual amount of the extraction solvent in Comparative Examples 1 to 4 are listed in Table 3. Taking the total weight of the PET fiber cloth and the residual propylene glycol monomethyl ether on the PET fiber cloth as 100 weight percent, after the filtering step, 20 to 60 weight percent propylene glycol monomethyl ether remains on the PET fiber cloth.

Then, ^{hot air was introduced at a volume flow rate of 10 Nm 3} /min to keep the surface of the PET fiber cloth at a temperature of 145 ° C for 20 minutes to vaporize propylene glycol monomethyl ether to dry the PET fiber cloth and obtain a Dry and decolorized fiber cloth, the whiteness (L value) of the dry and decolorized fiber cloth is greater than 75%.

After the drying step, the PET fiber cloth was weighed, and the residual amount of the extraction solvent on the PET fiber cloth was calculated. The weight of the PET fiber cloth after drying and the residual amount of the extraction solvent in Comparative Examples 1 to 4 are listed in Table 3.

The propylene glycol monomethyl ether of vaporization is collected by condenser condensation, after the condensate is cooled to 25 DEG C, measure the weight of the extraction solvent that collects, and can calculate the amount of the extraction solvent lost in the vaporization and condensation process. Loss of extraction solvent after drying = (residual amount of extraction solvent after filtration - residual amount of extraction solvent after drying - amount of condensation of extraction solvent after drying). The solvent condensation amount and solvent loss amount of the PET fiber cloth after drying in Comparative Examples 1 to 4 are listed in Table 3.

Finally, in order to prove that the method of applying microwaves in the present invention can improve the recovery rate of the extraction solvent, the recovery rate of the extraction solvent is calculated according to the following formula: the condensation amount of the extraction solvent after drying/the residual amount of the extraction solvent after filtration×100%. The recoveries of the extraction solvents in Comparative Examples 1 to 4 are listed in Table 3.

table 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Net weight of fiber cloth (g) 100 100 100 100 After S3 step Total weight of fiber cloth (g) 125 142.9 166.7 250 Residual amount of extraction solvent (g) 25 42.9 66.7 150 Extraction solvent content (wt%) 20 30 40 60 After S4 step Total weight of fiber cloth (g) 100.3 100.5 101.1 101.4 Residual amount of extraction solvent (g) 0.3 0.5 1.1 1.4 Extraction solvent residue (wt%) 0.3 0.5 1.1 1.4 Extraction solvent condensation amount (g) 20.0 34.8 54.1 128 Extraction solvent loss (g) 4.7 7.6 11.5 20.6 Extraction solvent recovery rate (%) 80.0 81.1 81.1 85.3

According to the content of Table 3, it can be known that the method of passing hot air to vaporize the extraction solvent will cause more extraction solvent to be lost, so the recovery rate of the extraction solvent cannot be improved. Specifically, after the drying step, the loss of the extraction solvent is 4 g to 21 g, and the recovery rate of the extraction solvent is 80% to 86%.

Therefore, according to the contents of Tables 1 to 3, it can be known that the operation mode of applying microwaves to vaporize the extraction solvent and dry the fiber cloth in this case can effectively reduce the loss of the extraction solvent and improve the recovery rate of the extraction solvent. Compared with the traditional operation method of drying the fiber cloth with hot air, it can have a better recovery rate of the extraction solvent.

[Advantageous effects of the embodiment]

One of the beneficial effects of the present invention is that the decolorization method for fiber cloth provided by the present invention can reduce the loss of the extraction solvent and improve the recovery of the extraction solvent through the technical solution of "applying microwaves to vaporize the extraction solvent" Rate.

Further, the decolorization method of fiber cloth provided by the present invention can pass the technical solution of "separating a part of the extraction solvent by filtration before applying the microwave", and firstly separate a part of the extraction solvent to reduce Energy consumption required for subsequent application of microwaves.

Further, the decolorization method of the fiber cloth provided by the present invention can reduce the loss of the extraction solvent through the technical scheme of "in the step of applying microwaves, the heat transfer direction and the mass transfer direction of the extraction solvent are the same", And improve the recovery rate of extraction solvent.

The contents disclosed above are only preferred feasible embodiments of the present invention, and are not intended to limit the scope of the present invention. Therefore, any equivalent technical changes made by using the contents of the description and drawings of the present invention are included in the application of the present invention. within the scope of the patent.

Fig. 1 is the step flow chart of the decolorization method of the fiber cloth of the present invention.

Claims (9)

A method for decolorizing fiber cloth, comprising: providing a fiber cloth with a dye attached; using an extraction solvent to extract the dye on the fiber cloth; applying microwaves to vaporize the extraction solvent, and obtaining a dry and The decolorized fiber cloth; and the extraction solvent collected, condensed and vaporized, and the recovery rate of the extraction solvent is more than 90%. The method for decolorizing fiber cloth according to claim 1, wherein the extraction solvent is extracted at a temperature of 70°C to 130°C. The method for decolorizing fiber cloth according to claim 1, further comprising: separating a part of the extraction solvent by filtration before applying the microwave. The method for decolorizing fiber cloth according to claim 3, wherein after filtering to separate the part of the extraction solvent, the total weight of the fiber cloth and the extraction solvent remaining on the fiber cloth is 100 weight percent, 5 to 70 weight percent of the extraction solvent remains on the fiber cloth. The method for decolorizing fiber cloth according to claim 1, wherein after applying microwaves, the total weight of the fiber cloth and the extraction solvent remaining on the fiber cloth is 100 weight percent, and the fiber cloth is 0 to 5 weight percent of the extraction solvent remains. The method for decolorizing fiber cloth according to claim 1, wherein the weight ratio of the extraction solvent to the fiber cloth is 10 to 30. The method for decolorizing fiber cloth according to claim 1, wherein, in the step of applying microwaves, the heat transfer direction and the mass transfer direction of the extraction solvent are the same. The method for decolorizing fiber cloth according to claim 1, wherein after applying the microwave, the temperature of the fiber cloth is higher than the boiling point of the extraction solvent. The method for decolorizing fiber cloth according to claim 1, wherein the dye on the fiber cloth is extracted 1 to 6 times using the extraction solvent.

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