Study on Polyurethane Adhesive for High Temperature Glass Ink

High temperature glass ink is composed of dyes, pigments, linkers, additives and other ingredients. As a carrier of pigments, solid particles such as powdered pigments can be mixed and connected, and the adhesive pigments can finally be attached to the surface of the printed matter. It should have good solubility, good pigment dispersion and high substrate adhesion. Polyurethane resin has excellent flexibility, adhesion and dispersion of pigments, so it has a wide range of applications in high temperature glass ink linkers. At the same time, with the enhancement of people's awareness of environmental protection, the requirements for food packaging bags are also increasing, and they need to be able to undergo high temperature treatment and kill all bacteria. Therefore, the polyurethane adhesive attached to it must also have a certain high temperature resistance. Performance.

Using self-made aromatic polyester polyols as soft segments, and BDO, NPG, MPD, CHDM and MDI as hard segments, polyurethane granules for high temperature resistant glass ink binders were synthesized by one-step method, and dissolved into adhesives with a solid content of 15%. The effects of the type and molecular weight of polyester polyols, the type and amount of chain extenders, the type of isocyanate and the isocyanate index on the properties of polyurethane adhesives were discussed. The results show that:

Polyurethane adhesives for high temperature glass inks require transparency and good anti-back tack, and the relative molecular mass of polyols has a certain influence on the properties of polyurethane adhesives. Adhesives made of polyesters with different molecular weights have a great influence on the bonding properties. The higher the molecular weight of polyester, the greater the viscosity of its glue, but too high the molecular weight of polyester will be detrimental to the permeability and bonding properties of the glue. It is very necessary to choose appropriate polyester molecular weight to improve the bonding strength of high temperature glass inks. The influence of the relative molecular weight of the polyol on the performance of the polyurethane adhesive is that when the relative molecular weight of the polyester polyol is small, the anti-stick performance of the polyurethane is poor; with the increase of the molecular weight of the soft satin, the sequence length is prolonged, and the macromolecules are flexible. The molecular arrangement can be fully carried out, and it is easy to be tightly packed to form crystals, and the transparency is poor. Therefore, it is advisable to first set the molecular weight to about 2000.

In the synthesis of polyurethane, active low molecular weight functional group compounds play the role of molecular chain extension when used together with isocyanates. They affect the relationship between the hard and soft segments of polyurethane, and thus affect the final properties of high temperature glass ink products. Adding chain extenders can correspondingly increase the content of polyurethane groups, increase their cohesive strength, polarity, and activity, so that the polyurethane adhesive and the bonded material can form material adsorption and chemical bonding, and increase the bond strength and heat resistance of polyurethane adhesives.

The self-made aromatic polyester polyol with a molecular weight of about 2000 is used as the soft segment, and BDO, NPG, MPD and MDI are used as the hard segment to synthesize the polyurethane adhesive. It can meet the requirements of high temperature resistant glass ink binder in terms of transparency, anti-back tack, hardness, softening point, adhesion, etc.