Basic knowledge of waterborne epoxy resin

Epoxy resin refers to a class of polymers containing more than two epoxy groups in a molecule.
water-based epoxy resin refers to a stable dispersion system in which epoxy resin is dispersed in the form of particles or droplets in a dispersing medium with water as its continuous phase.
what is epoxy
Epoxy resin refers to a class of polymers containing more than two epoxy groups in a molecule

.
because of the chemical activity of epoxy base, a variety of compounds containing active hydrogen can be used to open the ring, curing cross-linking to create a mesh structure, so it is a thermoso-solid resin.
classification of epoxy resins
Epoxy resins can be divided into several categories according to molecular structure type:
1
, shrunk glycerol ether epoxy
2
, shrunk glyceride epoxy
3
, shrunk glyceroid Amine epoxy resin
4
, line fat family epoxy resin
5
, lipid cycloethylene epoxy resin
among them, shrinking glyceline ether epoxy resin is composed of lively hydrogen-containing phenols or alcohols and epoxy chloropropane. It is currently the most widely used and dosed species, of which biphenol-based propane-type epoxy
resins (BPA
A
-type epoxy resins) are used the most.
was followed by shrinking glyceline epoxy resins.
characteristics of
epoxy resin (in the case of BPA type A) have many advantages:
1
, high regeneration performance
epoxy resin has a strong cohesion force, molecular structure dense. After curing, the epoxy system has excellent methic performance.
2
, strong adhesion
epoxy resin molecular chain contains the presence of polar hydroxyl and ether bonds, so that its curing material on metals, ceramics, glass, coagulants, wood and other substances have a high adhesion. Epoxy resins are lowly constricted when cured, resulting in low internal stress, which also helps to increase the adhesion strength.
3
chemical resistance
ethers, benzene rings and fatty hydroxyls in curing systems are not susceptible to acid-base erosion. In seawater, oil, kerosene,
10% H2SO4
,
10% HCl
,
10% HAc
,
10% NH3
,
10% H3PO4
and
3 The 0% Na2CO3
can be soaked for two years, while the
50% H2SO4
and
10% HNO3
are soaked at room temperature for half a year, and the
10% NaOH
(
100
degrees C) is soaked for one month and the performance remains the same.
4
, low curing shrinkage
cure shrinkage is generally
1
% to
2
%. It is one of the species with the smallest curing shrinkage in thermoso-solid resin.
5
, crafts good
epoxy resin curing basically does not produce low-molecular volatiles, so can be low-pressure molding or contact pressure molding. Can be paired with a variety of curing agents, product size is stable, good resistance and low water absorption.
6
, excellent electrical insulation
epoxy resin can be more than
35kv/mm
, is one of the thermooenstic resin intermediary electrical performance of one of the best varieties.
7
, good mold resistance
cured epoxy resin system resistant to most mold, can be used under harsh conditions.
it also has certain disadvantages:
1, most
several epoxy resin contains aromatic ether bonds, after exposure to sunlight easy to break the chain, so the weather resistance is poor.
2,
low temperature curing performance is not good, 10 degrees C or less may cure slowly, as far as possible to
ensure a certain curing temperature
;
4,
after curing is more brittle, elongation rate is small.
5,
resistance to mechanical shock and thermal impact difference.
water-based epoxy resin
water-based epoxy resin refers to a stable dispersion system in which epoxy resin is dispersed in the form of particles or droplets in a dispersion medium with water as a continuous phase.
conventional epoxy resin is diluted with organic solvents as a dispersion medium, which is not only costly, but also harmful to human body and environment during construction. To this end, the development of environmentally friendly water-based epoxy resin system has become a hot research topic.
according to the preparation method, epoxy resin hydration has several methods:
1
, mechanical method
that is, direct emulsification. Epoxy resin with ball mill, collage grinding, homogenizer and other grinding, through the role of emulsifiers, in a certain process to prepare water-based emulsion.
2
, the opposite method
by changing the volume of the water phase, the polymer from the oil-packed water
(W/O)
state to the water-packed oil
(O/W)
state, is a more effective method for the preparation of polymer resin emulsion.
3
, curing agent emulsification method
curing agent emulsification method is not an emulsifying agent, but the use of emulsification effect of curing agent to emulsify epoxy resin. This kind of curing agent is both cross-linking agent and emulsifier.
4
, chemical modified method
chemical modified method also known as self-emulsification method, the introduction of some hydro-hydrogenic groups into the epoxy resin molecular chain, or insertion or branching, so that epoxy resin to obtain the nature of self-emulsification.
according to the type of hydro-water-based group introduced, the hydroponic epoxy emulsion of chemically modified legal system can be divided into anion type, cation type and non-ion type.