Solvent dye dissolution method

Solvent dyes are a type of non-ionic dyes. Their molecular structure usually does not contain strong hydrophilic groups (such as sulfonic acid groups or carboxylic acid groups), so they are insoluble in water, but easily soluble in organic solvents or non-polar media (such as oils, waxes, plastics, fuels, etc.). The following is a detailed method for dissolving solvent dyes.

1. Basic characteristics of solvent dyes

Solubility:

Insoluble in water: Due to the lack of hydrophilic groups, it cannot form hydrogen bonds with water.

Soluble in organic solvents: such as alcohols (ethanol, methanol), ketones (acetone), esters (ethyl acetate), hydrocarbons (toluene, xylene), chlorinated hydrocarbons (dichloromethane), etc.

Application areas:

Ink, plastic coloring, fuel dyeing, wax products, metal markings, etc.

2. Methods for dissolving solvent dyes

1. Choose a suitable organic solvent

Match the solvent according to the polarity of the dye:

Polar solvents: acetone, ethanol, DMF (dimethylformamide), DMSO (dimethyl sulfoxide) are suitable for solvent dyes with slightly stronger polarity.

Non-polar solvents: Toluene, xylene, and mineral oil are suitable for non-polar dyes.

Examples of commonly used solvents:

Ethanol/methanol: Suitable for some polar solvent dyes (such as solvent red and solvent blue).

Acetone: Good solubility for most solvent dyes.

Toluene/xylene: Used for high-temperature dissolution requirements in plastics or inks.

2. Heating to promote dissolution

Method: Heat the solvent to 40-80°C (adjusted according to the boiling point of the solvent), and slowly add the dye while stirring.

Note:

Avoid exceeding the boiling point of the solvent (such as acetone boiling point 56°C, toluene 110°C).

High temperature may cause some dyes to decompose, please refer to the product manual.

3. Use mixed solvents

Applicable situations: When the solubility of a single solvent is insufficient, you can try mixed solvents (such as ethanol + acetone, toluene + isopropanol).

Example:

Solvent Yellow 43: Soluble in a mixture of toluene and n-butanol (4:1).

4. Adding cosolvents or plasticizers

Cosolvents:

Benzyl alcohol, glycol ether: Enhance the solubility of polar dyes.

Phthalates (such as DOP): Used as plasticizers when coloring plastics.

Plasticizers: In plastic processing, plasticizers (such as DOP, DOA) can help dyes disperse evenly.

5. Grinding or pre-dispersion

Nano-scale dispersion: For poorly soluble dyes, they can be ground into micro powders with dispersants (such as polyethylene wax) and then dispersed in solvents.

Premixing technology: The dye is mixed with a small amount of solvent to make a high-concentration mother liquor, and then diluted to the required concentration.

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