KR100731584B1 - Dyeing method of polylacticacid fiber - Google Patents

Abstract

A method for dyeing a PLA(Poly Lactic Acid) fiber is provided to improve the dyeability, by selecting dyes suitable for the PLA fiber and determining dyeing temperature suitable for the PLA fiber. A PLA fiber is dyed by disperse dyes selected from C.I. Disperse Yellow 42, C.I. Disperse Yellow 86, C.I. Disperse Orange 30, C.I. Disperse Red 54, C.I. Disperse Red 74, C.I. Disperse Blue 56, and C.I. Disperse Blue 374. The maximum dye temperature is a range of 100-110°C when the PLA fiber is dyed by the selected disperse dyes. The pH of a dye bath is controlled within a range of 4-6 when the PLA is dyed by the selected disperse dyes.

Description

Dyeing method of PolyLacticAcid fiber

1 is a chemical structural formula of PLA fiber,

Figure 2 is a chemical structural formula showing the combination of PLA fibers and dispersion dyes,

Figure 3a is a view showing the dyeing process of PLA fiber according to the present invention, Figure 3b is a view showing the dyeing process of PET fiber.

The present invention relates to a PLA fiber, and more particularly, to select a disperse dye having excellent dyeing resistance to PLA fiber among the conventional disperse dyes for PET fibers, and also set the dyeing temperature and pH according to the characteristics of PLA fibers weak to heat The present invention relates to a PLA fiber dyeing method for improving the dyeing property and stability of the fabric to PLA fiber, which had a problem in dyeability when dyed with a general dispersion dye for PET.

As consumers' living standards increase, human-friendly fibers are required in consideration of basic clothes, aesthetic and cultural functions, and even health.

In addition, as various environmental regulations are strengthened, cellulose-based regenerated fibers (recycled fibers including lyocells), chitosan fibers, soybean fibers, tencels, spider webs, bamboo fibers, and polylactic acids obtained from corn are obtained from natural raw materials ( Eco-friendly material fibers having excellent biodegradability such as PLA) fiber are emerging.

Here, biodegradation refers to conversion to low molecular weight compounds by enzymes secreted by microorganisms existing in light (ultraviolet) or nature during a process of decomposition. In the decomposition of the polymer material, first, the degrading enzyme secreted by the microorganisms out of the cells is adsorbed onto the surface of the polymer material, and the chemical bonds such as ester bonds, glycoside bonds and peptide bonds of the polymer chain are cleaved by the hydrolysis reaction. The hydrolysis mechanism of lactic acid polymer is initiated by addition of water molecules to the carbonyl group at the end of the fiber. As the molecular weight of the high molecular material decreases, the material collapses, and the product becomes a low molecular weight decomposition product of monomer units, that is, monomers or dimers, by enzymatic decomposition.

As shown in Figure 1, PLA fibers do not have a benzene structure of polyester, but have a structure similar to polyester in that the -COO- group is a repeating hydrophobic fiber.

As such, PLA fibers are connected by ester bonds similarly to PET fibers, and as shown in FIG. 2, dyeing is possible by hydrogen bonding with a disperse dye. Here, the hydrogen bond refers to a hydrogen (H) atom that is bonded to an element having a high electronegativity through an intermolecular bond, and electrostatically interacts with an atom (N, O, F) having a high electronegativity. This bond is easily formed with a relatively weak bond (about 8.4 to 41.9 kJ / mol or 2 to 10 kcal / mol) and can also be easily broken. In addition to the hydrogen bond, the PLA fiber and the dispersion dye are bonded to the hydrophobic bond, which is somewhat weaker than the PET fiber.

Meanwhile, PLA fiber (Lacton) has a higher melting point (Tm) and excellent Young's modulus than other biodegradable polymers. However, as shown in Table 1, PLA fibers have a lower melting point (Tm) and glass transition temperature (Tg) than PET fibers, and thus are subject to temperature constraints in dyeing, heat treatment, and ironing.

[Table 1] Comparison of properties of PLA fiber and PET fiber

Lacton polyester Gravity (g / cm 3)  1.27  1.38 Tm (℃)  175  260 Tg (℃)   57   70 Strength (g / d)  4.5 to 5.5  4.5 to 5.5 Stress (%)   30   30 Modulus (kg / ㎡)  400-600  1,200

In addition, PLA fibers are similar to polyester in that they are hydrophobic fibers, and are suitable for dyeing with disperse dyes. As shown in Table 1, due to the PLA fiber properties, dyeing properties of dyes are not similar to those of PET fibers. And the glass transition temperature is significantly lower than the PET fiber, the conventional dyeing method that has been used for PET fiber has a problem that is not suitable to reduce the physical properties of the PLA fiber.

Therefore, there is a need for a technical presentation on the selection, dyeing and processing of dispersion dyes suitable for PLA fiber.

The present invention has been made in order to solve the problems described above, it is an object of the present invention as a dye for PLA fiber dyeing by selecting a dye having excellent dyeability to PLA fiber among the dispersion dyes used for PET fibers.

In addition, it is an object of the present invention to provide a dyeing method that can improve the dyeability of the disperse dyes for PLA fibers by presenting suitable process conditions for applying the dye to the PLA fibers.

In order to achieve the above object, according to an aspect of the present invention, in the PLA fiber dyeing method, the dye for dyeing the PLA fiber, C.I. Disperse Yellow 42, C.I. Disperse Yellow 86, C.I. Disperse Orange 30, C.I. Disperse Red 54, C.I. Disperse Red 74, or C.I. Disperse Blue 56, C.I. Disperse Blue 374 It provides a PLA fiber dyeing method, characterized in that any one of the dyes.

In the PLA fiber dyeing method, the highest temperature at which the dyeing proceeds provides a PLA fiber dyeing method characterized in that it has a temperature range of 100 ~ 110 ℃.

In addition, the pH of the dye bath at the time of dyeing is adjusted in the range of 4 ~ 6, the R / C temperature has a temperature range of 50 ~ 60 ℃, the amount of alkali / reduction bleach used in R / C is 1/1 when PET fiber dyeing 2, the final setting is characterized by having a temperature range of 120 ~ 140 ℃.

Hereinafter, the dyeing process of the PLA fiber according to the preferred embodiment of the present invention will be described in detail.

1. Dyes and Samples

PLA fiber is a fiber obtained by the condensation reaction of lactic acid, and its structure is similar to that of PET fiber, and thus has a dyeing property with a disperse dye. Therefore, as shown in Table 2 below, after dyeing and analyzing the PLA fibers for 20 kinds of dispersion dyes for PET fibers, among them propose a suitable disperse dye for PLA fibers.

At this time, as a result of comparing the dyeing rate, color fastness, color, etc., a dye having a high dyeing degree of 75% or more is also selected for PLA fiber, and considering that PLA fiber is weaker in heat and alkali than PET fiber, Stain under mild conditions.

[Table 2] Disperse Dyes Used

Dye Energy type Dye category C.I. Disperse Yellow 42 Low Nitro C.I. Disperse Yellow 86 Low Nitro C.I. Disperse Yellow 126 Azo C.I. Disperse Yellow 211 Medium AZO C.I. Disperse Orange 30 AZO C.I. Disperse Orange 31 AZO C.I. Disperse Orange 44 Medium AZO C.I. Disperse Orange 80 AZO C.I. Disperse Brown 1 AZO C.I. Disperse Red 5 AZO C.I. Disperse Red 50 Medium AZO C.I. Disperse Red 54 AZO C.I. Disperse Red 74 Medium C.I. Disperse Red 177 AZO  C.I. Disperse Violet 33 AZO C.I. Disperse Blue 56 Low C.I. Disperse Blue 148 High Anthraquinon C.I. Disperse Blue 284 AZO C.I. Disperse Blue 319 AZO C.I. Disperse Blue 374

In addition, the PLA fiber is provided with a woven fabric using 100% PLA yarn (75D / 36 fil), Na ₂ CO ₃ 2g / l and Kierlon jet B con. (Non-ionic surfactant) 0.5g / l Pretreat at 60 ° C. for 20 minutes. In this case, in order to compare the PLA fiber and the dyeability, standard white PET fiber (75D / 36fil) is provided and used without a special pretreatment process.

2. Dyeing and Reduction Conditions

Figure 3a is a view showing the dyeing process of PLA fiber according to the present invention, Figure 3b is a view showing the dyeing process of PET fiber.

Here, since the PLA fiber is a hydrophobic fiber, it uses a disperse dye and dyes it at a high temperature and high pressure, so that it is dyed by a method similar to PET fiber (see FIG. 3B) using an IR dyeing machine.

As shown in FIG. 3A, the temperature of the dye bath starts at 50 ° C. and is raised by 2 ° C. per minute until 110 ° C. (2 ° C./min). Then, when the temperature reaches 110 ℃ is maintained for 40 minutes and cooled to 2.5 ℃ per minute until 70 ℃ (-2.5 ℃ / min) to complete the dyeing. At this time, the amount of dye used is 4% of the fiber weight (for example, dye 4% owf for 5g PLA fiber), the pH of the salt bath is set to 5 using AcOH / NaOAc buffer (buffer), The amount is 10 times the weight of the fiber (bath ratio 10: 1).

After dyeing, reducing washing (R / C) is carried out to remove dyes that do not penetrate into the fiber and are only on the outside. NaOH 0.5g / l and Na ₂ S ₂ O ₄ Treat with an IR dyeing machine at 60 ° C. for 20 minutes using 0.5 g / l (alkali / reducing bleach), wherein the amount of solution is used by the amount of the salt bath.

Referring to Figure 3a and Figure 3b, comparing the dyeing process of PLA fiber according to the present invention compared to the conventional PET fiber dyeing process, because the glass transition temperature and melting point lower than PET fibers in the properties of PLA fiber does not harm the physical properties of the fiber after dyeing They must be dyed at lower temperatures.

Therefore, in the present invention, the maximum temperature at which dyeing proceeds is lowered from 130 ° C. (PET fiber) to 110 ° C. (PLA fiber), and the R / C temperature is lowered from 80 ° C. to 60 ° C.

In addition, in the case of reduction washing (R / C), in consideration of the fact that PLA fiber is weaker in temperature and alkali than PET fiber, the amount of preparation used in the R / C is reduced by half (that is, NaOH 1.0g / l and Na ₂ S ₂ O ₄ NaOH 0.5 g / l and Na ₂ S ₂ O ₄ at 1.0 g / l 0.5 g / l, reducing the amount of alkali / reduced bleach by one half).

In addition, even in the final setting (F / Setting, final setting) PLA fiber is treated at 130 ℃, PET fiber at 160 ℃ each 60 seconds to lower the F / Setting treatment temperature.

Here, reduction washing (R / C) refers to an operation of removing dyes attached to the surface without using a reducing agent and a cleaning agent after staining of synthetic fibers, in particular, polyester fibers, by using a reducing agent and a cleaning agent together.

In addition, the bath ratio refers to the amount of the salt solution (water + dye + preparation, etc.) to the weight of the fiber.

In addition, the final setting refers to a treatment method of fixing the shape of a thread or fabric by heat treatment in the presence of moisture, and also includes heat fixation using thermoplastics such as twisting of a thread and synthetic fibers, so that color is better expressed after dyeing. do.

Although the dyeing process of the PLA fiber according to the present invention has been described above, the maximum temperature at which the dyeing proceeds is not limited to 110 ° C., and a temperature range of 100 to 110 ° C. is preferred.

In addition, the pH of the salt bath is not limited to 5 can be adjusted in the range of pH 4-6.

In addition, the R / C temperature is not limited to 60 ° C. and may have a temperature range of 50 ° C. to 60 ° C., and is not limited to 130 ° C. even in the final setting, and may have a temperature range of 120 ° C. to 140 ° C.

The dyeing evaluation through the dyeing process (see FIG. 3a) and the staining evaluation through the measurement of the dye absorption rate of the dyeing PLA fiber, the wash fastness and daylight fastness through the following process.

3. Colorimetric Data of Dye

The colorimetric degree of the dyed fabric was measured using a Datacolor SF 600 plus spectrophotometer (Datacolor International), and a D65 light source, 10 degree observer, was used.

4. Draining rate and fixation rate of dye

Based on the Kubelka-Munk theory, the K / S value is determined from the reflection value to determine the density of the dyeing concentration. Then, the adsorption amount of the dye using a UV-visible spectrophotometer establish the absorbance at the maximum absorption wavelength for each dye, the proportion (% E) of the dye absorption in the salt bath is Eq. Calculate from 1

% Reduction = (A ₀ -A ₁ ) / A ₀ × 100 ( Eq .1 )

At this time, A ₀ and A ₁ represent the absorbances of the initial salt bath and the residual bath at the maximum absorption wavelength, respectively.

5. Color fastness evaluation

The fastness of washing is based on the M & S C4A method, and 10 iron beads are added using 4 g / l of ECE detergent and 1 g / l of sodium perbirate, and the degree of contamination of the multifiber is evaluated by experimenting at 60 ° C. for 30 minutes.

Daylight fastness was assessed by Gray Scale after 20 or 40 hours of light irradiation using Xenon-arc (ATLAS Ci-4000) according to ISO 105 B02.

Looking at the results measured according to the method as follows.

6. Key Results

Table 3 shows the extraction rate of 20 dispersion dyes for PLA fiber. Referring to Table 3, C.I. Disperse Yellow 211, C.I. Disperse Orange 80, C.I. Disperse Brown 1, C.I. Disperse Red 177, C.I. Disperse Blue 319 had a low dyeing rate of less than 30%, and C.I. Disperse Yellow 42, C.I. Disperse Yellow 86, C.I. Disperse Orange 30, C.I. Disperse Red 54, C.I. Disperse Red 74, C.I. Disperse Blue 56, C.I. Disperse Blue 374 shows an excellent dyeing amount of 75 to 90%, showing the potential as a disperse dye for PLA fibers.

[Table 3] Removal rate of 20 dispersion dyes for PLA fiber

Table 4 shows the chemical structural formulas of seven kinds of dispersion dyes suitable for PLA fibers showing the potential as a dispersion dye for PLA fibers.

Table 4 Seven Dyes Suitable for PLA Fibers

 Dye Structure Molecular formula Molecular Weight (M.W) C.I. Disperse Yellow 86

C ₁₈ H ₁₅ N ₃ O ₄ S 369.40 C.I. Disperse Yellow 86

C ₁₆ H ₁₉ N ₃ O ₅ S 365.41 C.I. Disperse Orange 30

C ₁₉ H ₁₇ C ₁₂ N ₅ O ₄ 450.27 C.I. Disperse Red 54

C ₁₉ H ₁₈ ClN ₅ O ₄ 415.83 C.I. Disperse Red 74

C ₂₂ H ₂₅ N ₅ O ₇ 471.46 C.I. Disperse Blue 56

C ₁₅ H ₁₃ BrN ₂ O ₄ 365.18 C.I. Disperse Blue 374 - - -

Table 5 is a table comparing the dyeing shades of PLA and PET fibers, and shows seven dyes having excellent dyeing properties (CI Disperse Yellow 42, CI Disperse Yellow 86, CI Disperse Orange 30, CI Disperse Red 54, CI). Disperse Red 74, CI Disperse Blue 56, CI Disperse Blue 374) is shown comparing the brightness, saturation, color of the PLA fiber and PET fiber.

[Table 5] Color comparison between PLA fiber and PET fiber

 Dye Fiber L * a * b * C * H * Yellow 42 PLA 85.8 -5.1 82.8 83.0 93.5 PET 81.9 6.5 80.2 80.5 85.3 Yellow 86 PLA 79.4 13.6 87.6 88.6 81.2 PET 74.6 23.8 71.0 74.9 71.4 Orange 30 PLA 53.8 49.1 62.4 79.4 51.8 PET 48.4 42.6 47.2 63.6 48.0 Red 50 PLA 45.1 57.9 48.0 75.2 39.7 PET 39.1 51.1 30.8 59.7 31.1 Red 54 PLA 48.5 58.7 54.6 80.2 43.0 PET 46.3 53.6 43.8 69.2 39.3 Red 74 PLA 40.3 55.0 42.4 69.4 37.6 PET 38.8 48.5 26.0 55.0 28.2 Blue 56 PLA 32.5 19.0 -50.1 53.6 290.8 PET 32.4 6.2 -40.9 41.4 278.6 Blue 284 PLA 23.8 17.5 -40.0 43.6 293.6 PET 21.6 11.1 -29.4 31.4 290.7 Blue 374 PLA 21.3 2.5 -21.2 21.4 276.7 PET 28.0 -6.3 -21.9 22.8 254.0

Where C.I. The L and C values of all dyes except DisperseBlue 374 showed PLA fiber higher than PET fiber, indicating that PLA fiber is brighter and closer to pure color than PET fiber.

In addition, the yellow color of PLA fiber was clearer than PET fiber (greener, yellower), and the orange and red color PLA fiber was clearer than PET fiber (yelllower, redder), and the blue color was Except for Blue 374, PLA fiber was clearer than PET fiber (bluer, redder).

Table 6 is a table comparing the wash fastness of PLA fiber and PET fiber, the wash fastness of the seven dyes with excellent dyeability is C.I. Disperse Yellow 42, C.I. Disperse Red 74, and C.I. In the dyes except Disperse Blue 374, PLA fiber was 0.5 ~ 1 grade lower than PET fiber.

[Table 6] Comparison of washing fastness of PLA fiber and PET fiber

Wash fasteness stainig to Acetate (PLA / PET) Nylon (PLA / PET) Yellow 42 4-5 / 4-5 4-5 / 4-5 Yellow 86 3-4 / 4 3/4 Orange 30 3-4 / 4-5 3-4 / 4-5 Red 54 3/4 3/4 Red 74 3-4 / 3-4 3-4 / 3-4 Red 56 3-4 / 4 3 / 3-4 Blue 374Z 4-5 / 4-5 4-5 / 4-5

Table 7 shows the DE *, DL *, DC * values and grades of PLA and PET fibers before and after exposure, and the light fastness is C.I. Disperse Yellow 42, C.I. Disperse Yellow 86, C.I. Disperse Orange 30, and C.I. Disperse Red 54 was irradiated for 40 hours, C.I. Disperse Blue 56 and C.I. Disperse Blue 374 was irradiated for 20 hours.

[Table 7] DE *, DL *, DC * values and grades of PLA and PET before and after exposure

Disperse Dyes Grade (PLA / PET) DE * (PLA / PET) DL * (PLA / PET) DC * (PLA / PET) Yellow 42 4-5 / 4-5 3.92 / 2.72 -1.99 / -1.11 -2.17 / -0.50 Yellow 86 4-5 / 4-5 0.37 / 1.49 -0.23 / 0.22 -0.19 / -1.48 Orange 30 4-5 / 4-5 1.35 / 0.44 -0.08 / -0.24 -1.34 / -0.07 Red 54 4-5 / 4-5 2.10 / 1.55 -0.31 / -0.13 -2.07 / -1.46 Blue 56 4-5 / 4-5 4.31 / 1.84 -0.29 / 0.42 -4.25 / -1.66 Disperse Blue 374 2-3 / 2 5.24 / 2.94 3.81 / 2.33 3.16 / 0.78

Where C.I. In all dyes with the exception of Disperse Blue 374, PLA fibers showed relatively good light fastness compared to PET fibers, and C.I. Disperse Blue 374 has a low daylight fastness of 2 to 2.5 grades for both PLA and PET fibers.

In addition, C.I. In the other dyes except for Disperse Yellow 86, PLA fiber has a larger color difference before and after light irradiation than PET fiber, so that the daylight fastness of PLA fiber is slightly lower than that of PET fiber.

Although the dyeing method of the PLA fiber according to the present invention has been described above, the dyeing conditions (dyeing temperature, pH, etc.) and the selected disperse dye in the above method are not limited to the PET and PLA fibers, and are applicable to hydrophobic fibers. And other environmentally friendly textile materials.

As described above, the PLA fiber method according to the present invention shows a high dyeing property to the PLA fiber by selecting a dye suitable for PLA fiber from the existing dispersion dyes for PET dyeing properties that have been pointed out as a problem in using PLA fiber To improve.

In addition, by suggesting the dyeing conditions (dyeing temperature and pH, etc.) suitable for PLA fiber, it is possible to expand the range of use of PLA fiber, which is spotlighted as an environment-friendly, high value-added material.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above-described embodiments, which can be variously modified and modified by those skilled in the art to which the present invention pertains. Modifications are possible.

Accordingly, the spirit of the present invention should be understood only by the claims set forth below, and all equivalent or equivalent modifications thereof will belong to the scope of the present invention.

Claims (5)

In the PLA fiber dyeing method, The dye for dyeing the PLA fiber, C.I. Disperse Yellow 42, C.I. Disperse Yellow 86, C.I. Disperse Orange 30, C.I. Disperse Red 54, C.I. Disperse Red 74, or C.I. Disperse Blue 56, C.I. Using any of Disperse Blue 374 disperse dyes, When dyeing using the dye, PLA dyeing method, characterized in that the highest temperature at which the dye proceeds has a temperature range of 100 ~ 110 ℃. The method of claim 1, PLA dyeing method characterized in that the pH of the salt bath during dyeing using the dye is adjusted in the range of 4-6. The method of claim 1, When dyeing using the dye R / C temperature is 50 ~ 60 ℃ temperature range, the amount of alkali / reduction bleach used in R / C is NaOH 0.5g / l and Na ₂ S ₂ O ₄ 0.5g / l PLA fiber dyeing method characterized in that. The method of claim 1, When the final setting using the dye PLA fiber dyeing method characterized in that it has a temperature range of 120 ~ 140 ℃. delete

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