WO2019199248A1

WO2019199248A1 - Decolorizing method

Info

Publication number: WO2019199248A1
Application number: PCT/TR2018/050355
Authority: WO
Inventors: Kevin Jin Youn; Fuat GÖZAÇAN
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-04-10
Filing date: 2018-07-10
Publication date: 2019-10-17
Anticipated expiration: 2020-10-10

Abstract

The present invention relates to a decolorization method that provides specific desired effect on fabric denim by measuring the moisture content of fabric scraps and comprises the following process steps; a step of treating said textile product, a step of weighing dry fabric scraps, a step of wetting dry fabric scraps, a step of determining weight difference between dry fabric scraps and wet fabric scraps, a step of exposing said textile product and said fabric scraps together to ozone gas in tumbler.

Description

INNOVATION IN DECOLORIZING METHOD

Technical Field

This invention relates to a method for decolorizing a garment used in textile industry.

This invention particularly relates to a decolorization method that provides specific desired effect on fabric denim by measuring the moisture content of fabric scraps.

The Prior Art

Blue Jean or denim is one of the most popular fashion apparel in present days. Despite the long history of Indigo dye, the real commercialization of blue jean started during the 1860s for miners and, lumberjacks due to its durability. As denim started to incorporate washes in their fabric, more people started to wear. Now, denim has become a staple in majority of people’s wardrobe regardless of their social, racial or economic differences.

Jeans were initially worn rigid (non-washed) as this was sufficient for the early workers. As a move to increase its attraction and comfort, notable denim companies started to offer stone washed jeans during the 1950s.

With the increased demand for washed denim, denim finishing and wash dramatically developed over the last 30 years. Several dry processes were introduced like sand blasting (currently banned by many countries including Europe), whiskering, hand sanding, grinding (rip and tear) to make the garment more attractive to buyers. Along with the dry process, most laundries use wash techniques which uses pumice stone, enzyme, bleach, potassium permanganate, and laccase by themselves or a combination of these to achieve different colors and characters of the jeans. The most common denim washes are achieved by using stone, enzyme, bleach, potassium, and some with laccase.

Commonly used wash techniques:

Stone Wash

It creates a worn-out look (abrasion (high and low of blue)) using pumice stone in rotating wash machine. Stone is commonly used to chip out indigo, using its own gravity, hitting the garment’s surface, softening the fabric as well. The effects of the abrasion are most noticeable around the seam areas where the highs and lows are more pronounced due to the combination of fabric shrinkage and the stitching the holds the garment together. Since this does not oxidize the indigo, one would notice that the pocket lining is often dirty when a garment is washed using this method.

Bleach Wash or Potassium Permanganate

Bleach is a strong oxidizing agent. In the wash industry, the most widely used chemicals are sodium hypo-chlorite, calcium hypo-chlorite, hydrogen per oxide and potassium permanganate. These are used to oxidize the indigo dye which in turn brings the indigo tone down. Most bleach that are used is liquid that is why only it can only be removed evenly in a water bath. This method does not create a dirty pocket lining like stone wash.

Enzyme wash

This process gives denim a softer and worn-in look by breaking down the cellulose molecules naturally found in denim and several other materials with indigo and/or other dyes. It is very common for stone washes to be combined with this technique to speed up the process of creating a vintage look.

All these wash techniques involve many chemicals, used to either clean and neutralize the oxidant. Examples of the chemicals used are peroxide, pocket white, HAS, Sodium metabisulphite etc.

Due to the character of the Indigo dye and finishing of the Denim fabric, these wash methods commonly must use a lot of water along with chemicals and stone to process it. Sadly, almost the same amount of water used to process jeans goes back to mother earth, polluted with indigo dye, sludge from pumice stones and/or harmful chemicals.

Moreover, there was poor predictability in achieving the desired look in the prior art. The desired effect and color are sometimes not achieved. The variables affecting the desired look were not examined and were not completely understood. All these are due to the absence of a specified method which could improve accuracy in achieving the desired look. Some applications are encountered in the Patent research made about decolorizing textile product.The application found with no FR689377A is the initial discovery of the oxidation power of Ozone with moisture.

US1553042A disclosed how bleach is used to oxidize fabric.

CN1284896C use ozone to recycle the dyed cotton and direct oxidation is utilized.

In US6024766A, Ozone used to kill the enzyme that was used to wash jeans.

US201 10083282A1 focuses on the apparatus producing ozone gas, controlling ozone concentration as well as oxygen generation at the end of each cycle.

CN102071509A is related recycling scraps of denim and removing impurities using ozone In the document JP2008240224A, machine used to do bleach textile using Ozonated Water.

CN1287035C is about direct water transfer to garment and removing moisture (dehydration). Garment is exposed to ozone after removing some moisture from the garment.

US5241720A explained waste water treatment using ozone.

JP09031840A is about pre-treatment using ozone instead of hot water & chemicals.

As it can be understandable from these documents that they use ozone oxidation in their documents either direct oxidation or with the help of machinery. Finally, none of them is related to a catalyst to enable the slow moisture transfer of water to garment.

Consequently, the requirement to eliminate the disadvantages of the state of the art techniques being currently used for the decolorizing method for fabric denim has made it necessary to have an advancement in the related technical field. Purpose of the Invention

The invention relates to a decolorizing method for fabric denim developed to eliminate the abovementioned disadvantages and to meet the abovementioned requirements.

The main object of the invention is to give denim specific desired look. Because of the method which is the subject of the present invention, denim products having desired color, abrasion and effect are obtained.

Another object of the invention is to provide sustainable and repeatable method. In the prior art applications, the desired effect and color cannot be achieved consistently. The invention aims to overcome this problem.

Another object of the invention is to understand the relationship between moisture of fabric scraps, different fabric dye content and the ozone exposure time to obtain the desired look.

The details of this present invention will be discussed in the following sections. All these should be taken into consideration when assessment is made regarding the present invention.

Brief Description of The Figures

Figure 1 is a graphic showing average L values of all the fabrics which represents the lightness and darkness of the color for 3 different conditions.

Figure 2 is a graphic showing average L values of all the fabrics which represents the lightness and darkness of the color for 3 different exposure times.

Figure 3 is a graphic showing L values which represents the lightness and darkness of the color of Fabric A for 3 conditions.

Figure 4 is a graphic showing L values which represents the lightness and darkness of the color of Fabric A for 3 different exposure times.

Figure 5 is a graphic showing L values which represents the lightness and darkness of the color of Fabric B for 3 conditions. Figure 6 is a graphic showing L values which represents the lightness and darkness of the color of Fabric B for 3 different exposure times.

Figure 7 is a graphic showing L values which represents the lightness and darkness of the color of Fabric C for 3 conditions.

Figure 8 is a graphic showing L values which represents the lightness and darkness of the color of Fabric C for 3 different exposure times.

Figure 9 is a graphic showing L values which represents the lightness and darkness of the color of Fabric D for 3 conditions.

Figure 10 is a graphic showing L values which represents the lightness and darkness of the color of Fabric D for 3 different exposure times.

Figure 1 1 is a graphic showing L values which represents the lightness and darkness of the color of Fabric E for 3 conditions.

Figure 12 is a graphic showing L values which represents the lightness and darkness of the color of Fabric E for 3 different exposure times.

Figure 13 is a graphic showing L values which represents the lightness and darkness of the color of Fabric F for 3 conditions.

Figure 14 is a graphic showing L values which represents the lightness and darkness of the color of Fabric F for 3 different exposure times.

Figure 15 is a graphic showing L values which represents the lightness and darkness of the color of Fabric G for 3 conditions.

Figure 16 is a graphic showing L values which represents the lightness and darkness of the color of Fabric G for 3 different exposure times.

Figure 17 is a graphic showing L values which represents the lightness and darkness of the color of Fabric H for 3 conditions.

Figure 18 is a graphic showing L values which represents the lightness and darkness of the color of Fabric H for 3 different exposure times.

Figure 19 is a graphic showing L values which represents the lightness and darkness of the color of Fabric I for 3 conditions.

Figure 20 is a graphic showing L values which represents the lightness and darkness of the color of Fabric I for 3 different exposure times.

Figure 21 is a graphic showing L values which represents the lightness and darkness of the color of Fabric J for 3 conditions. Figure 22 is a graphic showing L values which represents the lightness and darkness of the color of Fabric J for 3 different exposure times.

Figure 23 is a graphic showing L values which represents the lightness and darkness of the color of Fabric K for 3 conditions.

Figure 24 is a graphic showing L values which represents the lightness and darkness of the color of Fabric K for 3 different exposure times.

Figure 25 is a graphic showing L values which represents the lightness and darkness of the color of Fabric L for 3 conditions.

Figure 26 is a graphic showing L values which represents the lightness and darkness of the color of Fabric L for 3 different exposure times.

Figure 27 is a graphic showing showing average L values of the fabrics which represents the lightness and darkness of the color for 3 different conditions when using polyester/nylon blend microfiber pieces.

Detailed Description of the Invention

In this detailed description, preferred embodiments of the invention are explained for a better understanding of the subject by creating no restrictive effect.

Most denim is yarn-dyed fabric with the warp yarn dyed with indigo dye and the filling yarns left undyed. The properties of the indigo dye account for the wide variety of color designs that are available on denim materials. Indigo is unique as a major textile dye, because it has a very low affinity for the cotton fiber.

Indigo dye in its normal form is a vibrant blue, it is insoluble in water, and it will not dye cotton fiber. In order for commercial Blue denim to be made and to obtain deep blue indigo dyed yarns, the color must be built in layers. The dye is layered by using multiple passes of the rope of yarn into the soluble dye and then exposing it to the air for oxidation. This multiple passing of yarn into dye is called dips. Normally, this process is repeated from three to twelve times to build up a deep indigo blue color.

When even darker shades are desired, a sulfur black or blue dye can be applied to the yarn before indigo dyeing. This is known as a sulfur bottom. If the sulfur dye is applied after the yarn has been indigo dyed, it is known as a sulfur top. Unlike indigo, the sulfur dye can penetrate into the core of the cotton fiber/yarn. The purpose of this process is to give the indigo dyed yarns a much deeper and darker shade or to slightly change the shade of the blue yarn to make it unique.

Sulfur colors can be yellow, grey, blue, green and more and they can be applied below or above indigo on the fabric. Blue jeans are blue but after the wash process, assorted color casts may be revealed due to the different combinations of dyes used. The beauty of indigo comes from its unique continuous fading while people wear it thus Denim laundries seek to create this look with various finishing techniques to make it more attractive to consumers. However, a lot of chemicals are used to do this. A major drawback of the wash process is the contamination of water created, but it manufacturers just accepted it as part of the process of making jeans.

Ozone has been used by denim laundries as an oxidizing agent when it comes in contact with moisture/ water. It was able to oxidize indigo and many different dyes, but the results looked flat, dull and gray and consequently not welcomed. This was because previous applications were not successful in selectively slowly transferring moisture to the garment in order for ozone to react with that moisture. These methods only involved a direct water application which does not create abrasion has proven to be unsuccessful in creating that vintage look.

At this point, it was found from the present invention that it is important and essential that the moisture should be transferred gently to the garment. In order to transfer gently to the garment, the fabric scraps can be used as the third element (catalyst). The fabric scraps (as known as the third elements or catalyst) are the cotton or cotton blend fabric scraps or polyester/ nylon blend microfiber fabric scraps which contain moisture.

The textile product means the garments which want to be decolorized. The fabric scraps (as known as the third elements or catalyst) oxidizes indigo in a way that creates the authentic vintage look (abrasion) and connects the dry garments to ozone. In this way, the fabric scraps as a superior wash element has the ability to completely replace bleach, stone, enzyme, laccase and potassium permanganate in the decolorization process without generating toxic elements that pollute the environment.

Moreover, it has been observed that changes in fabric scraps’ moisture can create looks that are hard to achieve in traditional methods and not have all the harmful by-products.

The first step of the method disclosed in the present invention is the selection of fabric. Because combination of dyes can affect tone and character or wash, it is important to understand the dye combination used in the fabric of garment in order to get the specific desired look. In case of heavy abraded look, dark colored fabric of garment is preferred. If a light wash is desired, a lighter colored fabric of garment is recommended. After choosing the fabric, dry process is performed on garments to achieve used or worn out look, and dry process includes hand sand, whisker, grinding and laser operation.

The next step is the desize process. The desize process is conducted to remove starch from the raw fabric of garment. In this process, enzymes, lubricant and/or wetting may be applied to the fabric of garment. And then, fabric of garment is rinsed and dried.

While the garments are being dried and cooled down, the fabric scraps are prepared for use. In this step, the cotton or cotton blend pieces can be used as fabric scraps to perform as a catalyst (the third element) for gentle moisture transfer. This is the critical stage in solving the problem of control moisture of fabric scraps. In this stage, the fabric scraps’ moisture is measured by the help of determining the weights of wet fabric scraps and fabric scraps.

First of all, the dry fabric scraps are filled in the bucket and weighed. It is important to make sure that none of the fabric scraps remain in the bucket after weighing. Then, by using a washer or any wetting method that can fully saturate the fabric scraps, fabric scraps is wetted. After saturating the fabric scraps, the fabric scraps are exposed to spin cycle to do extraction. Extraction can be performed with either a rotator or a press extract after wetting/saturating. While using the washer or perform any wetting method, setting a timer is crucial. In this way, according to desired effect and abrasion, time arrangements can be made. After extraction the wet fabric scraps are transferred back to the container to be weighed. Again making sure that none of the wet fabric scraps remain inside is important. Then, the wet fabric scraps are weighed. The amount of moisture content has a direct effect on denim look. This moisture content can vary between 10%- 100% depending on the look desired.

In the sample study, extraction time was set up at 3 minutes, and dry fabric scraps and wet fabric scraps are measured as 20 lbs (9,07 kg) and 35.55 lbs (16,12 kg) respectively. The percentage of weight differences due to the moisture is found 56 %. The amount of moisture can be increased by changing the wetting time and extraction time to get the desired effect and abrasion level.

There is a treatment process for the ozone decolorization process to obtain an aesthetically pleasing decolorized look or fashionably faded look in the fabric. The dry ozone treatment process includes loading the textile product and fabric scraps into a drum wherein the cotton fabric scraps are wetted with water (supplying and stirring ozone gas inside the drum, and rotating the air-tight drum.)

This study was made to understand how the different moisture contents of fabric scraps, dye composition of garment/ leg panel material and exposure time affects the resulting wash tone of the garment.

Below are the components/ elements included in the study:

Constant/ Fixed Elements¹

Ozone machine: 600grams per hour, 6% concentration of ozone

Tumbler: 300lbs

Variable Elements

Fabric Scrap Moisture (Starting from 10 lbs of dry fabric scraps)

Condition 1

50% moisture

¹ The different ozone concentration and tumbler size will also change the look of the garment as well as the time required for the oxidation to take place but for the purposes of this study, so this study limited to this ozone machine and tumbler size for focusing on the effects of the fabric scraps’ moisture, garment dye composition and exposure time only. 15 lbs (6,8 kg) after water bath and extraction

Flat/ clean look

Condition 2²

72% moisture

17.2 lbs (7,8 kg) after water bath and extraction

Regular stone/ Enzyme look

Condition 3

100% moisture

20 lbs (9,1 kg) after water bath and extraction

High Abrasion/ Acid look

Exposure Time³ (per leg panel, per condition)

Dark Wash = 15 mins

Medium Wash = 30 mins

Light Wash = 1 hours

Garment/ Leg Panel Dye Composition

Pure/ Regular Indigo

Indigo with Sulfur Top or Bottom

Pre-Reduced Indigo

Pre-Reduced Indigo with Sulfur Top or Bottom

A colorimeter/ spectrophotometer⁴ has used to have a consistent color reading as compared to reading based on human eye that is subject to human error and inconsistent color perception and/or light conditions.

The different leg panels, after washing with the said conditions and exposure times, were read in 2 areas wherein the color is the most consistent (usually darker spot). These two values where then averaged to get the L value which represents the lightness⁵ and darkness⁶ of the color.

² Mostly used condition

³ Oxidation Time. How long garment/ leg panel was exposed to ozone

⁴ Nix Color Pro. App Version 2.5.13; llluminant, D50; Observer, 2

⁵ 100 Value =White

⁶ 0 Value = Black It should be noted that for the light shade, it could have some variation due to the high and lows, the area that has the more consistent color has only chosen to read thus images of the actual leg panels provide better understanding on the wash changes.

Presentation of Results

Via visual observation of the average values of all the fabrics using Line Chart A (Figure 1 ) and Column Chart B (Figure 2), one can see that the progression of the change in wash color/ tone is much more pronounced when the fabric scraps have moisture that goes beyond around roughly 80% to 85%, such in the case in Condition 3.⁷ The slope of the line is the steepest in Condition 3 as compared to Condition 1 and 2 which were flatter in their slopes. This is not to disregard the slightly steeper slope of Condition 2 compared to Condition 1 as Condition 2 does have a noticeable abrasion⁸ not very apparent in Condition 1 . The graphics provided will also show that the contrast that is achieved becomes much higher as the fabric scraps are more saturated with water. Thus, if the 3 conditions should have ranked based on contrast, Condition 3 ranks the highest then Condition 2 comes in second and lastly, Condition 1 has the lowest contrast. Moreover, the value change from the different exposure times were a lot more significant in Condition 3. What one can deem from this is that the moisture transfer in Condition 3 is no longer as incremental as the two other conditions. It is no longer like a mist transfer but more of a shower of water being transferred.

Exposure time is a factor in making the entire garment closer to the lightest possible value but is not the main factor in achieving the distinct abrasion that our process is able to produce. The fabric scrap moisture is the key element in providing the pronounced change in wash color/ contrast. Condition 1 having low moisture⁹ in the fabric scraps produces a flat /clean look. Condition 2¹⁰ having a relatively higher moisture in the fabric scraps produces the more regular stone/ enzyme wash look. Condition 3¹¹ having the highest moisture concentration produces a more aggressive look like an acid wash feel.

⁷ Stronger ozone machine generator might lower this value, and can also depend on fabric scraps’ weight

⁸ The contrast between the lightest color to the darkest color of the garment.

⁹ 50% Saturation

¹⁰ 72% Saturation

¹¹ 100% Saturation Regarding the dye composition, what have discovered in Condition 3 is that regardless of the dye used and/or whether sulfur was used, the process according to invention is able to achieve the heavy abrasion with only the use of water and ozone. Condition 3 will be very hard to achieve in the context of Traditional washes. This type of contrast was only possible using a combination of pumice stones, corrosive chemicals, special techniques and / or very labor-intensive processes. The Dye composition differences are noticeable when less exposure time is applied with Condition 3 as the colors of the ones with sulfur top or bottom will be revealed in the dark and medium washes. However, when it goes to the light wash with the 3^rd condition, the dye differences are almost negligible.¹² Should a darker or medium wash be preferred while still having the distinct abrasion, a clean-up process can be done wherein the garment/ leg panels will go through an additional oxidation process using Condition 1 and having an exposure time of 10 to 15 mins. The experiment did not go beyond the 15 mins mark due to the high probability that the base color might noticeably fade with a longer exposure time. The cleanup process is targeted towards making the lightest portion of the garment become brighter by removing the residual sulfur/ indigo dye that was not removed during the initial wash with short exposure time and Condition 3 as well as minimizing the overall fade in base color.

Included in the appendix is the data that shows all the fabrics that were tested in the different fabric scraps’ moisture conditions and exposure time. Coton or coton blend fabric starps used in the tests. Line and column charts with data tables to provide quantifiable proof of the varying color, tone and contrast that goes along with the change in fabric scraps’ moisture conditions and exposure times. Information regarding each fabric dye composition is also provided for reference.

A test of polyester/ nylon blend microfiber fabric pieces provided an alternative material apart from cotton or cotton blend pieces. In the test, the moisture content used were Condition 1 , 2 and 3 and each had an exposure time of 30 mins in ozone, which is categorized in this case as a“light wash”. The L value of Condition 1 through 3 as seen in Figure 27 shows the same pattern as with the cotton/ cotton blend fabric. However, it should be noted that since this type of material absorbs much more water than the cotton or cotton blend scraps, extraction time needs to be longer to result in the desired fabric moisture. Moreover, this material also releases/ transfer moisture to the garment faster thus processing using this material should be closely monitored to avoid staining the garment.

¹² This is referring to the lightest portion of the garment/ leg panel. The color is very close to white in most of the fabric that we tested. The slight variation will appear slightly yellowish or grayish if one would closely inspect the garment/leg panel. Fabric Dye Compositions

Fabric A (Figure 3.4)

Pure Indigo

Medium Depth Indigo

Fabric B (Figure 5.6)

Sulfur Bottom

Vibrant deep Indigo

Fabric C (Figure 7,8)

Pure Indigo

Medium Depth Indigo with Red Cast

Fabric D (Figure 9.10)

Sulfur Bottom

Medium/ Heavy Depth Deep Indigo with Gray Cast

Fabric E (Figure 1 1 .12)

Pure Indigo

Medium Depth Indigo with Red Cast

Fabric F (Figure 13,14)

Pure Indigo

Light/ Medium Depth Indigo

Fabric G (Figure 15,16)

Pre-Reduced Indigo with Light Brown Sulfur Top Medium Depth Indigo with Soft Muddy Appearance

Fabric H (Figure 17,18)

Pre-Reduced Indigo

Heavy Depth of Indigo with a slight Red Cast Fabric I (Figure 19,20)

Pure Indigo with Blue/Black Sulfur Bottom

Light/ Medium Depth of Indigo with slight Soft Grey / Blue Cast Fabric J (Figure 21 ,22)

Pure Indigo

Medium Depth of Indigo

Fabric K (Figure 23,24)

Pure Indigo

Medium/ Heavy Depth of Indigo

Fabric L (Figure 25,26) Pre-reduced Indigo

Heavy Depth of Indigo with a slight Red Cast

Claims

1 . A method for decolorizing a textile product, characterized in comprising the following process steps;

• a step of treating said textile product;

• a step of weighing dry fabric scraps;

• a step of wetting dry fabric scraps;

• a step of extracting wetted fabric scraps after wetting dry fabric scraps;

• a step of determining weight difference between dry fabric scraps and wet fabric scraps in order to determine moisture content;

• a step of exposing said textile product and said fabric scraps together to ozone gas.

2. The method for decolorizing a textile product according to claim 1 , characterized in that the textile product is denim.

3. The method for decolorizing a textile product according to claim 1 , characterized in that a step of treating said textile product selected from individual or/and groups consisting hand sand, whisker, grinding and laser operation.

4. The method for decolorizing a textile product according to claim 1 , characterized in that said extraction step takes place in rotator.

5. The method for decolorizing a textile product according to claim 4, characterized in that said extraction step takes place in press extract.

6. The method for decolorizing a textile product according to claim 1 , wherein said fabric scraps are the cotton or cotton blend pieces.

7. The method for decolorizing a textile product according to claim 1 , wherein said fabric scraps are polyester/ nylon blend microfiber fabric pieces.

8. The method for decolorizing a textile product according to claim 1 , characterized in that said exposing step takes place in tumbler.

9. The method for decolorizing a textile product according to claim 8, characterized in that said tumbler is rotary tumbler.

10. The method for decolorizing a textile product according to claim 1 , characterized in that said wetted fabric straps have a moisture content of 10%-100%.