- Jan 02, 2018 -
The rising voice of ecological protection is promoting a new change in the leather industry, and that is why synthetic leather is becoming more and more pupular .
However , synthetic leather is easy to wear and tear when compared to genuine leather . In order to increase the gloss level and property and feeling , people began to research and produce synthetic leather finishing agent .
Leather finishing agent is the general name of a kind of leather auxiliaries for leather surface finishing and beautifying leather.Leather finishing agent can increase the appearance of leather, extend the use time of leather, significantly improve the quality and grade of leather products and increase the trade value, which is an important achievement in synthetic leather industry .
The leather finishing agent is made with film forming material, coloring material, solvent and auxiliary agent in a certain proportion, in which the film forming material is the basis of the leather finishing agent. PU leather finishing agent is that kind of agent which is placed polyurethane as the matrix of film forming material.Polyurethane is a kind of polymer with space network structure, which contains -NHCOO- repeat structure units. It is made up of isocyanate (monomer) and hydroxyl compound. Because of polyurethane molecules containing strong polar urethane, usually containing ester bond and ether bond, urea bond, allophanate bonds and other structures, so it has good oil resistance, toughness, wear resistance and aging resistance properties of leather finishing agent in many talent shows itself.
There are many polyisocyanates used in polyurethane synthesis, including TDI, MDI, NDI, HDI, HMDI and IPDI. The polyurethane made from aromatic diisocyanate, such as (TDI, MDI), contains the conjugated group that is easy to hair color. It is not light - resistant, poor weatherability, and the film is easy to yellowing.In order to fundamentally solve the problem of polyurethane yellowing and adapt to the use of white leather and light colored leather, polyurethane based leather finishing agent based on aliphatic diisocyanate HMDI and IPDI is the first choice for manufacturers.
In addition to having excellent yellowing resistance can, with suitable reaction activity, using HMDI/IPDI as a reactive polyurethane leather finishing agent of matrix synthesized is easier to control, reduce equipment requirements and process control difficulty, also make the products with higher stability, especially suitable for the preparation of waterborne leather finishing agent, has the development prospects broad.
In addition, the aliphatic ring structure with HMDI and IPDI in the molecular structure, a certain extent make up for the disadvantages of the inherent mechanical properties of aliphatic isocyanate due to the absence of a rigid benzene ring, the coating film of fast drying, high hardness, and has good chemical resistance and wear resistance.