Classification and characteristics of several water-based resins

Water-based acrylic emulsions
water-based acrylic emulsions (
PA
) are early applications and are still widely used. In preparation, different monomers, adjust dosages, and improve processes to control the distribution of polymer molecules in emulsion particles are used to obtain emulsions at different glassing temperatures (
Tg
) or different minimum film-forming temperatures (
MFFT
).
Among them, water-based acrylic resins have a variety of different classifications:
according to raw materials, in the preparation of acrylic emulsions, by adding styrene can improve the hardness of the paint film and reduce costs
(but will affect the film's yellowing
resistance);
different emulsification agents according to the application, there are also different ion types.
Water-based acrylic emulsion made of paint film has good weather resistance, not easy to yellow change, good hardness, high gloss characteristics;
application of self-interlinking, nuclear shell structure, soap-free polymerization and other technologies can significantly improve the performance of acrylic emulsions.
Among them, the self-interlinking polymerization technology can improve the solvent resistance, hardness, anti-scratch and other properties of the paint film, the nuclear shell structure makes the paint film effectively take into account the hardness and film-forming properties, soap-free polymerization technology can improve the luster of the paint film, water resistance and so on by reducing or not using emulsifiers.
can be distinguished from curing methods and can be divided into thermoplastic curing and thermostasteric curing, i.e. we commonly use single-group water-based acrylic emulsions and water-based hydroxypropyl acrylic dispersions.
Single-group water-based acrylic emulsion paint, long storage period, convenient construction, cost-effective, and widely used, but by its formation of thermoplastic coating film tightness is low, coating water resistance, solvent resistance, wear resistance in general, can meet the performance requirements of general products, not suitable for some high-end products.
hydrohydroxypropyl acrylic dispersion can prepare water-based two-part self-drying paint and water-based single-part baking paint, through cross-linking reaction to form a network-like cross-linking structure, greatly improving the density of the paint film. These dense coating film obviously improves the hardness of the paint film, scratch resistance, but also can hinder the role of water, organic solvents, greatly improve the materialization performance of the coating film.
water-based polyurethane dispersion
water-based polyurethane dispersion (
PUD
) is a more high-grade category of products. Usually made of isocyanate and polyol by polygasing reaction, given the diversity of isocyanate and polyols, there is a wide range of adjustments when preparation.
there are also many different categories:
can be distinguished from isocyanate species, can be divided into two categories of fat and aromatic. The paint film of the fat family has excellent weather resistance and yellowing resistance, which can be used for outdoor coating, while the aromatic family is used in interior decoration paint due to the lack of yellowing resistance.
from the types of polyols, mainly polyester and polyethers are more common. Most of the water-based polyurethane dispersions have excellent flexibility after filming.
polyester type has better stretching performance, flexibility, resistance to damage, solvent resistance and high temperature resistance. Polyether type has the characteristics of high strength, hydrolytic resistance and high elasticity, low temperature performance.
the process of synthesizeing water-based polyurethanes, hydro-based groups or hydro-water chain segments must be introduced. The most common are anionic carboxyl and sulfonate, there are also cations of seasonal ammonium ions, or non-ion polyoxyethylene long chains, hydrohydroxymethyl, etc.
is precisely because of the molecular structure of hydro-based groups, so many products made of paint film water-resistant, solvent-resistant performance is lacking. Most can be coupled with crosslinkers in the membrane process to further cross-link, so as to obtain a comprehensive performance of excellent products.
addition, there are also a large number of introductions in the synthesis process
-OH
or
-COOH
and other hydrophosphate groups into water-based hydroxy polyurethane dispersion products. This type of product with curing agent made of two-parts (
2K
) water-based paint comprehensive performance is even better.
water-based acrylic modified polyurethane dispersion
water-based acrylic resin in the film, often in terms of hardness and toughness is difficult to balance, glass temperature (
Tg
) is too high easy to film bad, too low is easy to anti-stick;
so often mix the two resins to obtain a product that combines the advantages of both.
a better way to do this is to make a nuclear shell structure particle with acrylic as its core and polyurethane as its shell by using nuclear shell structure technology during preparation. In this way, products with high hardness and low film temperature can be obtained.
at the same time, through acrylic, polyurethane raw materials adjusted, can obtain in film-forming, hardness, anti-adhesion, flexibility, adhesion and other performance of more balanced and excellent products.