KR101814180B1 - Dyeing method of natural leather using cochineal extract - Google Patents

Abstract

A method of dyeing natural leather using cochineal extract is disclosed. The method for dyeing natural leather using the cochiney extract comprises the steps of preparing a salt solution containing a cochineal extract component (step of producing a saline solution), and dipping the natural leather in the saline solution to dye the natural leather (dyeing step) .

Description

[0002] Dyeing method of natural leather using cochineal extract [

A method of dyeing natural leather using cochineal extract is disclosed.

The present invention was derived from the research conducted by the Small and Medium Business Administration (Project No. C0248912, development of highly sensitive leather fashion products using natural dyes) as part of the industry-university cooperation technology development project of 2014 by the Small and Medium Business Administration.

Most natural leather processing and manufacturing companies are currently conducting dyeing processes with synthetic dyes. Wastewater generated during the process is highly biodegradable (BOD) and chemical oxygen demand (COD), and contains heavy metals It causes serious environmental pollution problem by generating degradable malignant waste water. In addition, the compound of synthetic dyes used in the dyeing of natural leather causes the final natural leather product to lose its affinity with human body, causing problems such as various skin rashes, allergies or dermatitis. Therefore, There are often reports of side effects that may cause catastrophic harm.

Accordingly, in order to meet the needs of consumers who prefer environmentally friendly and harmless products as a means for preventing the above-mentioned problems, the natural leather processing and the use of synthetic dyes such as azo dyes, carcinogenic dyes, To the extent that the natural leather has been produced. However, in the case of infants and elderly people who are sensitive to the skin, there have been problems such as the occurrence of various skin diseases including atopic dermatitis even by use of general synthetic dyes.

As a typical method for producing natural leather, raw leather is prepared through a preparation process, a tanning process, a dyeing process and a painting process. The preparation process is a process for removing unnecessary hairs, fat, soluble proteins, etc. in the leather production under the alkaline condition by inputting the raw material blood, and the tanning process is a process of removing collagen protein and a tanning agent such as chromium, vegetable, aluminum and aldehyde, To make a stable fiber structure. Through these processes, the dyeing process, which is one of the important factors for determining the product value by giving various colors according to the commerciality of the natural leather products and the desire of the consumers and imparting flexibility to the leather, is carried out, And the coating process proceeds according to the tendency.

The conventional dyed natural leather is mostly dyed with synthetic dyes, so there is no beauty of the beautiful colors. In the synthetic dyestuff production stage, refractory malignant wastewater is generated. In the dyeing process of natural dyes, There is a problem that the environmental impact value of the leather manufacturing process is suddenly increased and the skin allergy is caused in the case of a soft infant or an elderly person.
The background of the present invention is disclosed in a study on the texture of leather by cochineal staining (Seo Jung-hee, dissertation request for master's degree from Ewha Womans University, 2010).

One embodiment of the present invention provides a method of dyeing natural leather using cochineal extract.

According to an aspect of the present invention,

Preparing a saline solution containing the cochineal extract component (saline preparation step); And

And a step of dyeing the natural leather by immersing the natural leather in the saline solution (dyeing step). The present invention also provides a method for dyeing natural leather using the cochiney extract.

The step of preparing the saline solution may include dispersing the cochineal extract powder in the liquid medium.

The liquid medium may comprise water, acetic acid, methanol, ethanol, ethyl acetate, acetone, or a combination thereof.

The natural leather may include bovine, sheep, sheep, crocodile or combinations thereof.

The dyeing step may be carried out under the conditions of a bath ratio of 1: 100, a pigment concentration of 10 to 300% (o.w.f.), a dyeing time of 20 to 120 minutes, a dyeing temperature of 40 to 90 ° C and a pH of 2 to 11.

The dyeing step may be carried out under the conditions of a bath ratio of 1: 100, a dye concentration of 300% (o.w.f.), a dyeing time of 40 minutes, a dyeing temperature of 40 캜 and a pH of 5.

The method for dyeing natural leather using the cochineal extract may further include treating the natural leather with a mordant before the dyeing step (pre-dyeing step).

The method for dyeing natural leather using the cochineal extract may further include treating the natural leather with a mordant after the dyeing step (post-mordanting step).

The mordant may include alum (AlK (SO ₄ ) ₂ ), copper sulfate (CuSO ₄ .5H ₂ O), ferrous sulfate (FeSO ₄ .7H ₂ O), or combinations thereof.

The method of dyeing the natural leather may further include dyeing the natural leather dyed with the cochineal extract with an additional dye.

The additional dyes may include yellow, white, green, or combinations thereof.

The natural leather may be colored in the colors of Purple (P), Red purple (RP), Yellow red (YR), Blue (B) or Purple blue (PB).

The method of dyeing natural leather using Cochiney extract according to one embodiment of the present invention can provide natural dyed natural leather which is harmless to the human body, environmentally friendly, excellent in dyeability, and has various colors.

FIG. 1 is a graph showing a change in the total amount of salt (K / S) according to the concentration of a dye.
2 is a graph showing a change in the total amount of salt (K / S) according to the dyeing temperature.
FIG. 3 is a graph showing a change in the total amount of salt (K / S) according to dyeing time.
4 is a graph showing the change in total salt amount (K / S) according to the pH of the salt bath.
FIG. 5 is a graph showing the change in the total amount of salt (K / S) according to the concentration of the mordant in the case of the pre-mordanting method.
FIG. 6 is a graph showing a change in the total amount of salt (K / S) according to the concentration of the mordant in the case of the postmeetting method.

Hereinafter, a method for dyeing natural leather using cochineal extract according to one embodiment of the present invention will be described in detail.

The method of dyeing natural leather using the cochineal extract (hereinafter simply referred to as " dyeing method ") comprises a step of preparing a saline solution containing a cochineal extract component (a step of producing a saline solution) And a step of dyeing natural leather (dyeing step).

As used herein, " cochineal extract " means a male of a cocus cucti and a red dye derived therefrom. The cochineal extract has also been applied to ancient Inca fabrics and has been exported to Europe after Columbus discovered the American continent and has been used as an important red-colored animal dye. However, research on the use of the cochineal extract for the dyeing of natural leather has hardly been attempted yet.

The step of preparing the saline solution may include dispersing the cochineal extract powder in the liquid medium. That is, the saline means a mixture of cochineal extract powder and a liquid medium. In this specification, the term " saline solution " is also referred to as " salt bath ".

The cochineal extract powder may be prepared by adding a crude cochineal extract to a liquid medium such as distilled water and acetic acid, and then heating to extract the cochineal extract component, followed by filtration, concentration, and lyophilization.

The liquid medium may comprise water, acetic acid, methanol, ethanol, ethyl acetate, acetone, or a combination thereof.

The natural leather may include bovine, sheep, sheep, crocodile or combinations thereof.

The dyeing step may be carried out under the conditions of a bath ratio of 1: 100, a pigment concentration of 10 to 300% (o.w.f.), a dyeing time of 20 to 120 minutes, a dyeing temperature of 40 to 90 ° C and a pH of 2 to 11.

In the present specification, the term "bath ratio" means the weight of the natural leather to the weight of the saline solution (or the mordant solution), and the "dye concentration" means the concentration of the dye component in the saline solution. Further, "o.w.f." in terms of the dye concentration means "on the weight of fiber" and means the weight of the natural leather.

For example, the dyeing step may be performed under the conditions of a bath ratio of 1: 100, a dye concentration of 300% (o.w.f.), a dyeing time of 40 minutes, a dyeing temperature of 40 캜 and a pH of 5.

The dyeing method may further include a step of treating the natural leather with a mordanting agent (pre-dyeing step) before the dyeing step. Alternatively, the dyeing method may further comprise treating the natural leather with a mordant after the dyeing step (post-mordanting step).

The pre-mordanting step and the post-mordanting step may be carried out at a bath ratio of 1: 100, a mordant concentration of 1 to 5% (o.w.f.), a mordanting time of 20 to 120 minutes, and a mordant temperature of 40 to 90 ° C. For example, the pre-mordanting step and the post-mordanting step may be carried out under the conditions of a bath ratio of 1: 100, a mordant concentration of 5% (o.w.f.), a mordant time of 40 minutes, and a mordant temperature of 40 ° C.

The mordant may include alum (AlK (SO ₄ ) ₂ ), copper sulfate (CuSO ₄ .5H ₂ O), ferrous sulfate (FeSO ₄ .7H ₂ O), or combinations thereof.

The dyeing method may further comprise dyeing the natural leather dyed with the cochineal extract with an additional dye.

The additional dyes may include yellow, white, green, or combinations thereof.

In the dyeing method, the natural leather may be colored with a color of Purple (P), Red purple (RP), Yellow red (YR), Blue (B) or Purple blue (PB).

Hereinafter, the present invention will be described with reference to the following examples, but the present invention is not limited thereto.

Samples and reagents

The commercially available bark was refined and used as a sample. Amur cork tree, Cochinil, Gromwell and Indigo were purchased and used as dyes. The first class reagent was used as the mordant alum (AlK (SO ₄ ) _{2 12} H ₂ O), ferrous sulfate (FeSO ₄ .7H ₂ O), copper sulfate (CuSO ₄ .5H ₂ O) and other reagents.

Manufacture of dyes

50 g of cochineal was added to 1 L of distilled water, and then 5 ml of acetic acid was added to prepare a saline solution and the saline solution was heated. When the salt solution started to boil, the solution was further heated for about 60 minutes at a low temperature, and then filtered. The filtrate was concentrated by using a vacuum rotary evaporator at 40 ° C for 5 hours and then dried in a freeze dryer to obtain a dye (that is, a coloring matter powder).

dyeing

The thus prepared dyes were subjected to dyeing with an IR stainer (Daelim Starlet) at a ratio of 1: 100, dye concentration of 10 to 300% (owf), dyeing time of 20 to 120 minutes, dyeing temperature of 30 to 70 DEG C, (Dye concentration), dyeing temperature, dyeing time, and pH were evaluated by comparing total dyeing amount (K / S) after dyeing by using a dyeing machine (Model: Engineering, Model DL-6000) Here, a liquid mixture of distilled water and acetic acid was used as the liquid medium in the saline solution.

Mordant

Alum (AlK (SO _{4) 2)} as a mordant, copper sulfate (CuSO _{4 and} 5H ₂ O) or ferrous sulfate (FeSO _{4 and} 7H ₂ O) to to, yokbi 1 used: 100, from 40 ℃ 20 bungan line mordant Or afterwards. Mordant type, mordant concentration 1 to 5% (owf), or mordant salt amount was evaluated.

Salt loading  And surface color measurement

The surface reflectance was measured at intervals of 10 nm in the range of 400 nm to 700 nm using a handy-type color difference meter (Color System Co., Model JX 777), and the K / S value was calculated by the following formula (Kubelka-Munk equation) And the sum of the measured K / S values (Total K / S) was compared in order to exclude the color change factor.

[Equation 1]

K / S = (1-R) ² / 2R

R: surface reflectance, K: extinction coefficient, S: scattering coefficient

The change of color according to the dyeing condition, the type of mordant and the concentration of the mordant was measured by using the L ^* , a ^* , b ^* values and the hue (Hue) of the CIELAB color system using a handy type colorimeter (Color System Co., Model JX 777) ), Brightness (Value), and chroma (Chroma).

Evaluation results

<Change in total amount of salt (K / S) according to dye concentration>

FIG. 1 shows changes in the total salt amount (K / S) according to the dye concentration when dyeing at a bath temperature of 1: 100, a dyeing time of 40 minutes, a dyeing temperature of 40 ° C and a pH of 5.

Referring to FIG. 1, the total amount of salt (K / S) tends to increase as the dye concentration increases, and it has been found that the dye has a maximum value at a dye concentration of 300% (o.w.f.). This is because as the concentration of the dye in the salt bath increases, more dyes migrate to the skin and become dyed, resulting in a stronger color depth.

<Change in total dyeing amount (K / S) according to dyeing temperature>

(K / S) according to the dyeing temperature when dyeing under the conditions of 1: 100, dye concentration of 300% (o.w.f.), dyeing time of 40 minutes and pH of 5 is shown in FIG.

Referring to FIG. 2, the total dyeing amount (K / S) was increased as the dyeing temperature was increased, and reached a maximum at a dyeing temperature of 70 ° C. This is because the aggregates of the pigment molecules decrease as the dyeing temperature increases, and the pigments rapidly and easily diffuse into the inner skin. However, when the dyeing temperature is 50 ° C or higher, the skin tends to become harder and the dyeing temperature of 40 ° C is judged to be appropriate.

<Change in total dyeing amount (K / S) according to dyeing time>

(K / S) according to dyeing time when dyeing at a dyeing temperature of 40 ° C and a pH of 5 is shown in FIG.

 Referring to FIG. 3, as the dyeing time was increased, the total amount of salt (K / S) was increased and the maximum value was found at 120 minutes of dyeing time. However, when the dyeing time is longer than 60 minutes, the skin tends to become harder and the dyeing time of 40 minutes is appropriate.

<Change in total salt amount (K / S) according to pH of salt bath>

4 shows changes in the total amount of salt (K / S) according to the pH of the dye bath when dyeing under the conditions of a bath ratio of 1: 100, a dye concentration of 300% (o.w.f.), a dyeing temperature of 40 캜 and a dyeing time of 40 minutes.

Referring to FIG. 4, the total salt amount (K / S) was increased as the salt bath was changed to acidic, and the maximum value was obtained at pH 2. However, when dyed in a salt bath having a pH of 5 or less, that is, at a pH of 2 to 3, the whiteness tends to become very hard, and it is judged that a pH of around 5 is a proper acidity.

&Lt; Variation of total manganese content (K / S) according to mordant type, mordant concentration and mordanting method >

Changes in the total salt amount (K / S) according to the type of mordant, mordant concentration and mordanting method are shown in FIG. 5 and FIG.

FIG. 5 is a graph showing the change in the total salt amount (K / S) of the pre-mildew. In this case, the dyeing conditions were 300% (o.w.f.) of cochineal extract pigment, 40 ° C for dyeing temperature, 40 minutes for dyeing and pH 5. Total manganese (K / S) tended to increase with increasing concentration of mordant in the case of myeon by myeongbang, showing the maximum value at 5% (o.w.f.). The maximum salt concentration (K / S) was found at the mordant concentration of 3% (o.w.f.) in the case of manganese sulfate. In the case of ferrous sulfate fermentation, the total amount of salt (K / S) at 1% (o.w.f.) showed the maximum value, and then decreased at 1% (o.w.f.).

6 is a graph showing the change in the total salt amount (K / S) in the case of post-mordant treatment. In this case, the dyeing conditions were 300% (o.w.f.) of cochineal extract pigment, 40 ° C for dyeing temperature, 40 minutes for dyeing and pH 5. In the case of post mordant by alum, the total salt amount (K / S) was the maximum at the mordant concentration of 5% (o.w.f.). The total salt content (K / S) was the highest at the mordant concentration of 5% (o.w.f.) in the post mordants by copper sulfate. In the case of post mordantation with ferrous sulfate, the total salt concentration (K / S) was the maximum at the mordant concentration of 4% (o.w.f.).

Referring to FIG. 5 and FIG. 6, the case of pre-dyeing showed a higher dyeability (that is, a total amount of salt (K / S)) than that of post-dyeing.

&Lt; Variation of surface color depending on the type of mordant, mordant concentration and mordanting method >

Table 1, Table 2 and Table 3 show changes in surface color depending on the mordant type, the mordant concentration and the mordanting method for the skin dyed with the cochineal extract pigment. The following Table 1 shows the case of pre-mordanting, the following Table 2 shows the case of post-mordanting, and the following Table 3 shows the case of mixed dyeing. In order to obtain the results shown in Table 3, first, a cochineal extract pigment was used to perform dyestuff dyestuffing, and then 10%, 30%, and 50% of one of the other three dyes (yellowish, , 70%, 90% and 100% (owf), respectively. In the following Tables 1, 2 and 3, L ^* represents lightness, the + a ^* direction represents a hue change to red, the -a ^* direction represents a hue change to green, and the + b ^* It indicates the color variation of a, -b * direction indicates a change in color of blue, ΔE ^* _ab denotes a color difference, H denotes a color (Hue), V represents the lightness (Value), C is chroma ( Chroma). In the following Tables 1 and 2, Al represents alum, Cu represents copper sulfate, and Fe represents ferrous sulfate.

L ^* a ^* b ^* ΔE ^* ab H V / C Non-mordant salt 35.82 32.12 8.78 58.08 3.89R 3.48 / 6.35 Mordant Concentration (%, o.w.f.) Al One 33.99 23.96 -6.83 60.12 4.46 RP 3.24 / 5.00 2 32.36 24.26 -7.61 61.65 4.12 RP 3.08 / 5.03 3 32.04 24.82 -9.02 62.16 3.61 RP 3.05 / 5.10 4 28.13 25.02 -9.17 65.19 3.30 RP 2.67 / 5.18 5 24.27 26.29 -9.22 68.93 3.12 RP 2.29 / 5.31 Cu One 33.50 28.01 -3.83 62.59 6.55 RP 3.19 / 5.74 2 31.48 32.82 -5.59 68.06 5.67 RP 2.99 / 6.78 3 31.07 33.38 -6.08 68.32 5.41 RP 2.95 / 6.92 4 32.42 31.49 -5.74 66.23 5.50 RP 3.08 / 6.58 5 32.56 31.01 -4.88 65.63 5.98 RP 3.10 / 6.42 Fe One 27.33 11.94 -11.87 68.14 2.94P 2.63 / 2.10 2 27.56 10.33 -11.96 67.73 3.80P 2.65 / 2.12 3 31.07 10.28 -11.92 64.75 4.05P 2.99 / 2.19 4 31.35 10.26 -11.36 64.61 4.69P 3.01 / 2.20 5 31.59 9.53 -10.37 64.15 5.26P 3.04 / 2.27

Referring to Table 1, in the case of the lightness (L ^* ), the whitening resistance of all mordants was lower than that of untreated whitening (i.e. In the case of the color sensibility index (a ^* ), it was found that the greenishness of the mushroom treated with all mordants decreased compared with that of the untreated greenish mushroom (ie, mushroom greenhouse). In the case of the color sensibility index (b ^* ), the tendency to increase blue tended to be decreased with respect to all mordants in comparison with that of untreated wool (ie, untreated wool). In the case of color (H), red purple (RP) system color was observed at the preblending with alum and copper sulfate, and Purple (P) system color at the prebasing with ferrous sulfate.

L ^* a ^* b ^* ΔE ^* ab H V / C Non-mordant salt 35.82 32.12 8.78 58.08 3.89R 3.48 / 6.35 Mordant Concentration (%, o.w.f.) Al One 41.04 17.81 -6.29 49.48 4.19 RP 3.93 / 3.62 2 40.89 16.07 -6.68 49.93 3.56 RP 3.92 / 3.21 3 40.72 15.80 -7.61 49.96 2.68RP 3.90 / 3.15 4 40.37 15.74 -8.07 50.84 0.00RP 3.87 / 0.00 5 38.83 15.43 -8.69 52.26 0.00RP 3.71 / 0.00 Cu One 37.69 14.63 -7.51 50.48 0.00RP 3.60 / 0.00 2 37.52 13.62 -8.80 51.43 0.00RP 3.58 / 0.00 3 36.23 11.87 -8.89 51.84 0.00RP 3.46 / 0.00 4 35.78 11.15 -9.73 52.42 0.00RP 3.41 / 0.00 5 34.46 10.80 -9.98 52.83 0.00RP 3.28 / 0.00 Fe One 27.76 4.98 -4.49 55.83 8.70P 2.56 / 0.53 2 27.05 3.74 -4.83 56.21 6.16P 2.49 / 0.38 3 26.27 3.67 -4.75 57.47 4.36P 2.37 / 0.32 4 21.78 2.56 -4.24 60.50 0.12P 2.05 / 0.10 5 25.08 3.26 -3.47 54.37 3.84P 2.63 / 0.27

Referring to the above Table 2, in the case of lightness (L ^* ), the hue of the alum and copper sulfate was generally increased as compared with the untreated hue, and the color tended to be brighter. However, And the color tended to decrease. In the case of color sensitivity index (a ^* ), the tendency to increase green tended to decrease with the decrease in post hue. The color sensibility index (b ^* ) decreased in comparison with the untreated wool, indicating a tendency to increase blue color. In the case of hue (H), the color of the RP series was observed at the postmulsion by alum and copper sulfate, and the color of the P series was observed at the postmulsion by the ferrous sulfate.

L ^* a ^* b ^* ΔE ^* ab H V / C Cochin Neal 35.82 32.12 8.78 50.08 3.89R 3.48 / 6.35 dyes Concentration (%, o.w.f.) Yellowish white 10 62.19 12.03 5.28 10.89 1.70YR 6.05 / 2.38 30 60.60 12.00 7.80 13.24 3.30YR 5.89 / 2.62 50 60.29 10.30 12.11 17.44 7.17YR 5.86 / 2.87 70 60.06 10.11 12.48 17.88 7.49YR 5.84 / 2.89 90 58.55 9.65 14.13 19.85 8.25YR 5.69 / 3.05 100 57.74 8.76 18.88 24.08 9.17YR 5.61 / 3.59 Flesh 10 59.85 15.43 -3.83 4.58 6.78 RP 5.82 / 2.84 30 49.64 15.50 -4.50 12.71 5.75 RP 4.81 / 2.99 50 47.44 16.13 -4.61 15.03 5.56 RP 4.60 / 3.04 70 44.71 18.24 -4.63 17.18 5.35 RP 4.34 / 3.39 90 44.16 19.15 -4.95 17.67 4.90 RP 4.28 / 3.57 100 57.04 17.14 -4.55 5.57 5.80 RP 5.54 / 3.37 side 10 57.58 4.64 -9.44 16.86 6.75PB 5.59 / 1.42 30 49.75 -3.94 -16.62 29.81 8.00B 4.82 / 3.48 50 44.65 -3.83 -18.01 30.80 8.65B 4.33 / 3.70 70 44.01 -3.45 -18.16 32.82 8.91B 4.27 / 3.77 90 23.76 2.71 -19.70 45.58 3.64PB 2.32 / 4.13 100 18.59 6.04 -21.44 48.31 5.89PB 1.80 / 3.74

Referring to Table 3, when mixed with yellowish white, the lightness (L ^* ) was increased compared with that of a single Cochinil stain, and the hue became brighter. The color sensibility index (a ^* ) was decreased by yellowish white mixed dyeing, and the greenish trend increased with increasing yellowish white pigment concentration. The color sensitivity index (b ^* ) was increased by yellowish white dyeing, and the yellowish coloring tendency increased with increasing yellowish white pigment concentration. The color difference (ΔE ^* ab) was lower than that of single staining, and increased gradually with increasing dye concentration in mixed staining. Color (H) was R color in cochineal single staining and Yellow red (YR) color was main color in yellowish white mixed staining.

The lightness (L ^* ) was higher than that of Cochinil single staining in the mixed dyeing. In the case of color sensitivity index (a ^* ), the tendency to reddish was decreased in mixed dyeing compared to that in single dyeing, but the tendency to increase in red color tended to increase with increasing concentration of seed coloring. In the case of color sensitivity index (b ^* ), the tendency to yellow tended to decrease, while the tendency to increase blue tended to increase with increasing concentration of child coloring matter. Color (H) showed the color of RP series.

(L ^* ) was higher than that of Cochinil single staining. However, when the concentration of the dye was higher than 90% (owf), it decreased and the color became darker. In the case of color sensitivity index (a ^* ), green tendency was increased by mixed dyeing, and red tendency decreased with increasing dye concentration, but then increased again. In the case of color sensitivity index (b ^* ), blue tendency increased, and blue tendency increased with increasing concentration of the side pigment. In the case of color difference (ΔE ^* ab), it was lower than that in single staining and gradually increased as the concentration of dye in mixed staining increased. In the case of saturation (C), it was lower than that of single dyeing and increased with increasing dye concentration. Colors showed purple blue (PB) and blue (B) colors.

From the above results, it can be confirmed that the use of cochineal extract as natural dye for fashion material production can be confirmed, and cochineal extract can be utilized for fashion leather product development by applying it to natural leather dyeing for fashion clothing product production, It is expected that it will contribute to the development of fashion natural leather.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, . Accordingly, the scope of protection of the present invention should be determined by the appended claims.

Claims (12)

Preparing a saline solution containing the cochineal extract component (saline preparation step);
Dipping natural leather in the salt solution to dye the natural leather (dyeing step); And
Dyeing the natural leather dyed with the cochineal extract with an additional dye,
Wherein said additional dye comprises yellow, white, foliar, or a combination thereof. &Lt; RTI ID = 0.0 &gt; 18. &lt; / RTI &gt; The method according to claim 1,
Wherein the step of preparing a saline solution comprises dispersing a cochineal extract powder in a liquid medium. 3. The method of claim 2,
Wherein the liquid medium comprises water, acetic acid, methanol, ethanol, ethyl acetate, acetone or a combination thereof. The method according to claim 1,
Characterized in that said natural leather comprises bovine, sheep, sheep, crocodile or a combination thereof. The method according to claim 1,
Wherein the dyeing step is carried out under the conditions of a bath ratio of 1: 100, a dye concentration of 10 to 300% (owf), a dyeing time of 20 to 120 minutes, a dyeing temperature of 40 to 90 DEG C and a pH of 2 to 11 Method of dyeing natural leather used. 6. The method of claim 5,
Wherein the dyeing step is carried out under a condition of a bath ratio of 1: 100, a dye concentration of 300% (owf), a dyeing time of 40 minutes, a dyeing temperature of 40 캜 and a pH of 5. The method according to claim 1,
Further comprising a step of treating the natural leather with a mordanting agent before the dyeing step (preliminary dyeing step). The method according to claim 1,
Further comprising the step of treating the natural leather with a mordant after the dyeing step (post-mordanting step). 9. The method according to claim 7 or 8,
Wherein the mordant extract comprises a cochineal extract characterized by comprising alum (AlK (SO ₄ ) ₂ ), copper sulfate (CuSO ₄ .5H ₂ O), ferrous sulfate (FeSO ₄ .7H ₂ O) Method of dyeing natural leather used. delete delete The method according to claim 1,
Characterized in that the natural leather is colored in the colors of Purple (P), Red purple (RP), Yellow red (YR), Blue (B) or Purple blue (PB) Way.

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