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Methods to improve the performance of polyurethane resins

Update Time:2011-05-27   Writer:Arima
Polyurethane with a lot of advantages, they were widely used in: paint, ink, adhesives, leather finishing agents, leather, gloves, lubricant and so on. Leather finishing agent as an example: the manufacturing process of leather finishing is an important part. It can increase the beauty and durability of leather to improve the quality, variety and expand the scope of use. One film-forming polyurethane coating agent performance, hiding power, firmly bonded, excellent physical properties of the coating can greatly improve the level of leather, this highly regarded and extensive attention.
Most water-based PU is mainly prepared from the emulsion, containing hydrophilic groups of the PU as the main curing ingredients, dry film can not be effective if the hydrophilic component into the crosslinked network, the dried coating formed by water Easy swelling. In addition it lacks the two-component solvent-based PU film can be cross-linking density and high molecular weight, so the water dispersion coating water resistance, solvent resistance, heat resistance and gloss of the poor, serious limiting the scope of its use. Therefore, often used to improve the crosslinking density of the coating to improve the water resistance of the coating emulsion.
Commonly used cross-linked in two ways: one is the synthesis of PU prepolymer, adding functionality greater than 2, polyols, raw deal directly associated PU prepolymer, the prepolymer will be well dispersed water and macromolecular chain extension, and finally the formation of emulsion.
This method is also called before the cross-linking method, the shortcoming is easy to make pre-polymer viscosity increases, the more difficult to disperse in the water, affecting the stability of emulsion. In recent years, new multi-functional groups of crosslinking agent and chain extender and the synthesis of the screening is very active, has become a water-based PU to improve mechanical properties and water resistance of one of the main. Another way to cross-linking method, the use of PU anions with carboxyl emulsion crosslinking, the crosslinking reaction occurred in the PU carboxyl molecules, there is aziridine, imine carbon and metal salts, carried out at room temperature crosslinking. Such crosslinking agents typically are added in the use of PU emulsion,
Because of its fast rate of crosslinking reaction, gelation and emulsion breaking short period of time. Cross-linking method can be successfully resolved hydrophilic PU emulsion coating problems, but additional cross-linking agent to form a two-component coating agent to the construction inconvenience, this method uses less.
We are now a series of modified silicone resin introduced into the PU leather, polyurethane coating agents, polyurethane adhesives, shoe materials, polyurethane coatings, printing ink to go, found by contrast test engineers can solve the current water-based PU PU and oil products problems exist. A copy of the products described below:
First, the adhesive:
The series for the modified silicone crosslinking agent, can enhance the synthetic leather and polyurethane substrates with different adhesion between the coating material to a corresponding increase in coating and adhesive, bringing water solution and smoothness of feeling. Can replace more toxic aziridine crosslinker.
Second, the wetting agent:
This series of products designed to improve between the polyurethane and polyurethane coating materials and different coating materials, the wettability between the substrate and also can be used as foam polyurethane synthetic leather conditioning agents and leveling agents.
Third, the uniform pore-forming agent:
The series products are mainly used to improve the coating into the muscle, thereby improving the final touch of leather and surface mobility. The series does not contain hydroxyl groups, can serve as an effective and uniform pore wetting agent.
Fourth, leveling agent:
This series of products can give surface roughness of polyurethane synthetic leather. Wet process to improve the surface water vapor permeability bass, leveling; dry process, the increase in anti-sticking of PU leather, and a silky feel.
V. foam regulator:
The series is designed for wet slurry into the leather of polyurethane foam in the process control, cell structure to a homogeneous cluster hole vertical slab type. As well as anti-foaming effect, providing smooth layer of the epidermis, or bass.
VI, PU resin modifier:
The products contain active groups, or hydroxyl terminated polyether terminated silicone modifiers, can be directly involved in the reaction slurry can also be used as functional additives added to give the polyurethane synthetic leather bass and better surface water vapor permeability, air permeability, better low-temperature deflection, better anti-sticking, higher wear resistance, excellent surface smoothness, good foam stability or processability. At the same time with the polar solvents, non-polar solvent, polyol and isocyanate in a very good compatibility.