Direct dye? What is it? The direct dye is the class of dyestuff which is used directly to the substrate in the alkaline or neutral bath. They create full shapes on linen and cotton without mordanting and can also be useful to silk, wool or rayon. It gives bright colors but exhibits poor wash.
Different after treatments are useful for improving the wash fastness of these direct dyes and these dyes are considered as the after treated direct colors. These are molecules that adhere to the fabric molecules without any help from other chemicals. These are defined as the anionic dyes with substantively for cellulosic fibers that is simply applied from the aqueous dye bath having sodium chloride or sodium sulfate and an electrolyte.
The process of dying with direct eyes is very simple, the direct dye is the process that is carried out in the slight alkaline dye bath at or near the boiling point but it has the different after treatment like cationic dye fixing, for enhancing wet fastness which has been needed for most direct dyeing. And in this field, vipul organics is known as one of the best direct dyes manufacturers because they have deep knowledge.
Direct dyes are useful on wool, leather, paper, silk, cotton, and nylon. They are also useful as pH indicators and as biological stains.
Do you know about the paper industry?
Paper industries are broadly using the forms of dyes last hundreds of years. By seeing the growth in the industry of paper, it can be safely assumed that dyes for the paper industry have a very promising future. Given below is the comprehensive list of different grades of paper that are open to dyeing.
- Writing and printing paper
- Copier papers
- Decorative paper
- Tissues such as toilet, towel, napkin or facial
- Boards and cover papers
- Envelopes
- Label, laundry bags, and posters
- Packaging papers
The useful dyes have cationic direct dyes and sulfur dyes. Other than these two options, acid dyes and basic dyes are also useful. Sulfur dyes are decreased alkaline solutions. For an instance to get the Direct Black color – their professionals do few chemical reactions and bring the dye color. So if talking about cationic direct dye, few features make it suitable towards the use in the paper are –
- A planar molecular structure
- An extended conjugation
- An excess of positive charge over the negatively charged surface groups
What are the criteria to choose dye?
- Proper shade
- Affinity
- Showing light fastness
- Showing bled fastness
- Offers stability to humidity and temperature
- Lower or not at all metamerism
- Safe to handle
- No effect to any other paper process or parameters
What are the new trends that are followed in the paper dyeing industry?
- The trend goes towards the new coloration strategies which are fueled, pressures from environmental watch doges, and production price.
- Sophisticated high-speed machines are driving the reduction in uses of traditional simple dyes and raising demand to the modified basic and direct dyes.
- The perfect shift to continue size, dyeing, and press dyeing (for ex – Direct Black 22).
- New opportunities seeing new applications such as carbon fewer papers and thermal papers
You can now turn and go forward towards eco-friendly dyes –
- Dyes which are free of dangerous amines (like Direct Black 22)
- Dyes which are rid of heavy metals.
- Biodegradable dyes