The polyurethane resin used in the ink is generally made of a polyester/polyether polyol and an isocyanate, and has a molecular force of about 20,000 to 40,000. Its solvents are mainly benzene, ketone, ester solvents as the main solvent. In the research and development process, according to the environmental requirements of the ink factory and the printing factory, the corresponding benzene-free ink resin can be prepared by using a keto ester solvent or an alcohol ester solvent.

Ink polyurethane resin features：

1. Excellent adhesion fastness to film substrates
Polyurethane resin ink segment contains polar groups such as carbamate, allophanate ester, ester bond, ether bond, and polar groups formed on the surface of many polar substrates such as PET, PA, etc. Hydrogen bonds, in turn, form a linker with a certain degree of linking strength. After the polyurethane resin is made into an ink, it is printed on a polar plastic substrate surface with excellent adhesion fastness.

2. Good affinity and wettability with pigments
Polyurethane resins for inks are generally prepared from polyester or polyether polyols, alicyclic diisocyanates and diamine/diol chain extenders and have a molecular weight of about tens of thousands. Due to the introduction of the urea bond in the PU resin, a polyurethane-urea resin (PUU) is formed so that it has good dispersion wetting properties to the pigment.

3. Good resin compatibility
The polyurethane resin for ink has good compatibility with aldehyde and ketone resin, vinyl resin, etc. The user can add it according to the actual situation and his own craft formula to improve the ink's overall performance.

4. Excellent yellowing resistance
In the preparation process, the polyurethane resin for printing ink mainly uses aliphatic polyester and aliphatic isocyanate as the main raw materials for synthesis. Compared with aromatic polyurethane, it has excellent optical stability, and the film has excellent yellowing resistance after film formation.

5. Excellent film formation
Ink polyurethane resins are structurally different from polyurethane resins used in other fields. Traditional polyurethanes mainly react with polyester polyols/polyether polyols with isocyanic acid to produce hydroxyl terminated polyurethane resins. The polar groups in the molecular structure are carbamates. Mainly ester, molecular cohesion is insufficient to meet the filming performance requirements of ink resin. Therefore, the use of polyurethane resins for inks to introduce urea groups on the basis of conventional polyurethanes greatly improves the cohesive strength and film-forming properties of the resins themselves.

6. Wide compatibility of organic solvents and good solvent release

Solubility of the organic solvent to the resin is achieved by the polarity of the solvent molecule attracting solute molecules, which is commonly known as the same type of miscibility; traditional polyurethane resin has extensive compatibility with organic solvents, ketones, esters, benzenes, etc. Non-alcoholic organic solvents are excellent solvents.