Flax fiber is a bast fiber obtained from plant stems and has the highest strength (for example 2-3 times that of cotton) and low elasticity among vegetable fibers. Due to the waxes in its structure, these fibers show a natural shine. Linen fabrics wrinkle easily, but can also be easily ironed.
Since these fibers have a good heat insulation feature, they show a cool-keeping feature and are therefore preferred especially in summer clothes.
Jute fibers are also bast fibers like linen, and due to the difficulty in bleaching, the usage areas of these fibers are packaging material, carpets, etc. has been limited to
Thanks to the changes made in jute by chemical processes, these fibers can be mixed with wool, polyester and viscose for special areas of use.
At the same time, they are preferred to be used instead of polypropylene or polyurethane as packaging material in foreign countries due to their ecological (environmental) nature.
Both flax and jute fibers are used for dyeing cotton fibers. It can be dyed with direct, sulfur, reactive and pigment dyestuffs.
As it is known, flax consists of fiber bundles, not fibers alone, and these bundles are interconnected with pectin.
Since this pectin substance will be broken down by the effect of strong bases, fiber bundles are also broken down in a strongly basic environment, especially at high temperatures.
Therefore, Working with hot basic liquors should be avoided when dyeing linen..
Another point to be noted is that due to the hardness of the flax fibers, it is difficult for the dyestuff to penetrate them completely and properly.
For this reason, the following points should be considered while dyeing the fibers in question;
1- For tightly woven fabrics that will be dyed in one color, first dyeing the threads instead of the fabric and weaving the fabric with these threads.
2-Using auxiliary substances that increase the ability of the dyestuff to penetrate into the fibers and support uniform dyeing.
3-Using dyestuffs that do not have much affinity for fibers.
4-Do not go above 80°C in order not to cause hardening of the fibers during drying.
An issue that has gained importance in linen dyeing in recent years is the effect of enzymatic processes on color yield.
The controlled enzymatic treatment of linen fabric with cellulases provides partial removal of pectic materials from the flax fiber.
The more open structure of the fiber ensures that the aqueous solutions of the dyestuffs and chemicals used in the finishing processes are more absorbed.
Non-enzymatically treated fabrics are dyed more slowly with direct and reactive dyestuffs than those treated with cellulases under various conditions.
In a research done The effect of using ultrasound during pretreatment and subsequent dyeing of linen fabrics with sodium perborate was investigated.
It was determined that the whiteness degrees of the bleached fibers in the presence of ultrasound were higher.
Color yields obtained at 50°C in the presence of ultrasound were even slightly higher than those obtained with the conventional method at 80°C.
In addition, an increase was detected in the wet fastness of the samples stained in the presence of ultrasound.
In another study, the dyeing properties of flax fibers treated with chitosan were examined.
According to the findings, it was determined that the dyeing speed of the fibers increased significantly, and the rubbing and washing fastnesses increased.
Linen can be dyed in bobbin or fabric form.
Dyestuffs, dyeing method and the device to be used are selected according to the place where the finished product will be used.
To obtain yarn-dyed woven fabric, linen yarns are dyed in the form of bobbins.
Coils must be loosely wound.
Otherwise, the dye liquor cannot penetrate the inside of the bobbin sufficiently and as a result, it cannot be dyed.
In addition, the winding frequency of the coils in the same batch should be homogeneous.
It is recommended to use special (telescope or elastic) bobbins for cross bobbin dyeing.
If, after bleaching, the packages are subjected to an intermediate drying and then dyed, it is better that the dye penetrates every part of the yarns.
Linen dyeing involves many highly technical processes: composition of dye liquor, temperature, contact time with fabric, rinsing, soaping, drying techniques, etc.
Different methods and devices can be used for dyeing linen fabrics.
Dyeing in jet and overflow type machines is not recommended due to the risk of fabric abrasion and breakage.
The most commonly used device is the jigger, which has the ability to work with a fabric with a width of 2,5 meters.
However, the impregnation method is preferred for dyeing thick fabrics.
Two processes are recommended to obtain reproducible dyeings with the best rendering properties of Life;
- For reactive dyestuffs: After applying the dyestuff according to the impregnation method and keeping it in the cold, the process should be done in an open-width washing machine.
- For cube dyestuffs: Pad-jig method should be preferred.
Since the amount of foreign matter contained in flax fibers is high, it is essential to remove them before dyeing in order to obtain good fastnesses.
This can be done by boiling the linen with soda solution before dyeing it or even bleaching it afterwards.
These fibers can be dyed with dyestuffs that dye cellulose (direct, reactive, etc.) to give good wet fastnesses.
Dyestuffs with high durability and good penetration properties should be used in dyeing.
Different types of dyestuffs can be used, but the performance of each is different.
The place where the textile product will be used should be considered in the selection of dyestuff.
The properties of the dyestuff groups most commonly used in dyeing these fibers are given below.
Direct Dyes:
These dyestuffs are water-soluble and have low color fastnesses.
For this reason, direct dyestuffs can be preferred in cases where color fastness is not very important.
Cube Dyes:
These dyestuffs have good color fastnesses and high resistance to light and bleaching.
Dissolving them is a delicate process and can lead to uneven uptake by the fibres.
Pigment or cube acid methods are generally used in dyeing linen with cube dyestuffs.
Reactive Dyes:
Reactive dyes are used to obtain bright colors.
They show good resistance to light, with few exceptions they have low resistance to bleaching.
The point to be considered when dyeing linen fabric is that these fabrics shrink when exposed to high temperatures. For this reason, reactive dyestuffs that dye in the cold should be preferred.
As a dyeing method, two-step method is generally recommended.
Before dyeing the fabric, finishing processes such as dirt repellency, softening, water repellency should be avoided,
because they are very difficult to remove and at the same time they can cause abrasion in dyeing.
DYEING OF JUTE FIBERS
Cotton and jute rank first and second in world cellulose fiber production.
Compared to cotton, the various applications of jute are inconvenient due to the inherent deficiencies of the fiber.
In recent years, serious studies have been carried out for the production of special and value-added jute.
When it comes to dyeing these fibers, direct, sulfur, reactive and pigment dyestuffs can be used.
The use of sulfur dyestuffs of jute materials and the most suitable reducing agent, Na2S, is undesirable for ecological reasons.
In the study, the use of an environmentally friendly liquid jaggery (a brown colored sugar obtained from the sap of the palm plant) was investigated instead of Na2S as a reducing agent for ecological dyeing.
In the same study, it was determined that the K/S values of the dyeing processes made with sulfur dyestuffs using sodium sulfide (Na2S) and liquid jaggery were comparable to washing, rubbing and light fastnesses.
Jute/cotton blends are important as the main starting point in the upholstery and apparel textile industry, which is a completely new sector for jute.
In order to benefit more from jute and jute/cotton blended products, commercially viable technologies need to be developed that can eliminate the processing problems of these fibers. One of the problems that limit the application to jute products is color change under light, ie fading.
Very few dyestuffs can reach the light fastness of cotton in jute.
Fastness values in jute are generally 0,5-1,5 points lower than cotton, and sometimes the decrease can reach 2-3 points.
In the blending of jute with cotton, the problem is alleviated due to the cotton component; however, especially if the jute ratio is high, the blended fabric itself cannot meet the features expected from clothing and upholstery fabrics.
In order to obtain high light resistance in products containing jute; Due to the very good light fastness of dyed polyamide fibers, 1:2 metal complex dyes, which have come to the fore again, have been used for dyeing jute and jute/cotton mixed fabrics.
In one study, chemical modification was applied using a cationizing agent to give cotton the ability to be dyed with 1:2 metal complex dyestuffs.
It has been stated that this process improves light and washing fastness.
In addition, it was determined that post-treatments with polyquaternary amine derivative-based cationic substance after dyeing improved the washing fastnesses and did not affect the light fastnesses much.
In another study, the effects of various dyestuffs and finishing processes on the UV protection properties of jute/cotton blended fabrics were investigated.
It has been determined that bleaching with H2O2 makes fabrics more permeable to UV rays.
From the spectral analysis, it was observed that monochlortriazine-based reactive dyestuffs containing cyanuric chloride as a nucleophile group were more effective in UV protection.
Both flax and jute fibers It can be dyed with direct, sulfur, reactive and pigment dyestuffs used in dyeing cotton fibers.
In the selection of dyestuff, the place where the textile product will be used should be taken into consideration.
In addition, appropriate dyeing methods should be selected considering the differences in the structures of these fibers.
The most important problem in linen dyeing is that these fibers become brittle at high temperatures and are damaged by strong bases (in the presence of air oxygen).
This problem can be eliminated by using cold dye dyes and taking care not to rise above 80°C during drying.
One of the most important problems in jute dyeing is insufficient light fastness.
For this reason, the use of 1:2 metal complex dyestuffs with high light fastnesses, which we have recently known from PA dyeing, in jute dyeing is being investigated.
It is stated that a light fastness value as high as 6 can be obtained in modified and dyed jute.
It is also said that an increase in dye uptake and an improvement in washing fastness are observed in modified jute.
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