Study on the preparation and performance of two-part water-based epoxy coatings

Two-group water-based epoxy coating preparation and performance research
Shi Jiaxuan, Cui Cancan, Guo Xiaojun, Han Zhongzhi, Sun Zhaoxing, Wang Lei, Ding Chao, Li Shi, Kang Shaoxuan, Duan Shaoming
(China Petroleum Group Engineering and Technology Research Co., Ltd., Tianjin 300451)
Abstract
: Through a series of screening and comparative tests of water-based epoxy emulsion system, curing agent system,
n
(epoxy base):
n
(live hydrogen), pigmentation system and additive system, a two-component water-based epoxy coating with good mechanical performance and excellent corrosion resistance is obtained.
keywords:
water-based epoxy emulsion; mechanical properties; corrosion-resistant properties; two components; Paint
0
Introduction
With the increasingly strict control of volatile organic matter (
VOC), domestic and foreign research efforts on water-based coating raw materials, finished products
and applications have been unprecedentedly improved. Water-based epoxy coatings are widely used because of their good construction adaptability, high adhesion to many kinds of substrates, and the ability to cure at room temperature and in humid

. But the water-based epoxy coating itself is also defective: first, due to the large surface pressure of water, water-based epoxy coating for steel wetting is poor, easy to shrink holes, poor adhesion problems; The introduction of a large number of hydro-hydrogenic groups on the chain section will greatly reduce the cross-link density of the water-based epoxy coating, thus affecting the bonding strength of the coating, while the introduction of a large number of hydro-hydroprosive groups and the reduction of cross-linking density will result in a decrease in the corrosion resistance of the coating.
this study from the water-based epoxy emulsion, water-based epoxy curing agent, pigments and other aspects of research, through corrosion-resistant performance testing and testing, developed a good corrosion-resistant performance of the two-component water-based epoxy coating formula.
1
test part
1.1main raw materials
and equipment
water-based epoxy emulsion
A, B, C
; water-based epoxy curing agent
D (highly active polyamine), E (modified fat addition)
, a resin company;
ethyl glycol butyl ether
1, wet molybric mica powder, molybric acid, talcum powder, gas phase silicon dioxide, Tianjin Jiangtian Chemical
Technology Co.,
Ltd.;
QXD
coating fine meter,
FED115 oven
,
FA2004N
electronic balance, high-speed dispersion machine and so on.
1
.2coating
preparation
according to the amount in table 1 formulation, first add deionized water, dispersants, deblisters and moisturizers, stir well at high speed, and then add wet molybric mica, molybric acid, talcum powder, gas phase silicon dioxide and graphene, stirred evenly, grinding, until the fineness of the hydrated water is less than 60 m. A flash rust inhibitor, fungicide and epoxy emulsion (speed less than 1,000 r/min, temperature below 60 degrees C) is then added to the ground water slurry, and the thickener regulation system viscosity is added to the mixing side. Finally, 200 mesh filter is used to get the A-part. The water-based epoxy curing agent and propylene glycol methyl ether were mixed evenly, and the 200 mesh filter was prepared to obtain the B-part.
1 Water-based epoxy coating formulation
raw materials
fastraw materials
surface percentage/%
A parts
thypolic acid
15.0-20.0
deionized water
20.20. 0 to 25.0
talcum powder
15.0 to 20.0
dispersants
0.5 to 1.0
gas phase silica
0.2 to 0.3
Wetting agent
0.1 to 0.5
Graphene
0.3 to 1.0
debostering agent
0.1 to 0.5
aluminum tripolyphosphate
1.0 to 5.0
leveling agent
0.1 to 0.5
zinc phosphate
3.0 to 8.0
anti-flash rust agent
0.3 to 0.5
epoxy emulsion
30.0 to 40.0
microbicides
0.3 to 0.5
B parts
thickeners
0.3 to 0.5
water-like epoxy curing agents
60.0 to 80.0

wet moth mica
10.0 to 20.0
glycol butyl ether
20.0 to 40.0
1.3 model
preparation
in accordance with the standard requirements, preparation of horse mouth iron sheet, blast steel plate and test rod. After mixing the A and B parts prepared in 1.2 according to a certain proportion, set aside 20 min to remove the bubbles, and then carry out the construction work. The coating thickness for testing the performance of the coating is 25 m, and the coating thickness for testing corrosion resistance is more than 200 m (3 to 4 channels). Place the model at room temperature to maintain 7 d, followed by a performance test.
2
Results and Analysis
2.1 Water-based
Epoxy Emulsion and
Hydration
Eoxy curing agent determination
, B, C and curing agent D, E in accordance with the epoxy base and lively hydrogen material ratio of 1:1 for the test, by comparing the comprehensive performance of varnish, screening the best comprehensive performance of the resin curing agent system, the test results can be seen in Table 2.
table 2 varnish comprehensive performance
performance
AD
BD
CD
AE
BE
CE
table dry time/min
5
10

12
30
40
80
shock resistance/cm
40
40
40
40
50
50
Bend/mm
2
2
2
2
1
1
Adhesion/Class
2
2
2
1
1
1
50 g/L NaCl
(normal temperature)
3 d after foaming
3 d after foaming after br 5 d after foaming after 8 d
12 d after foaming
5 d after foaming
from table 2 results can be seen: curing agent D activity is higher, table drying speed is faster, coating strength is faster, but the coating is more brittle, flexibility and impact resistance is poor; However, C's molecular weight is too large, resulting in poor corrosion resistance, and water-based epoxy A has a small molecular weight and relatively poor flexibility. Therefore, this paper selects water-based epoxy emulsion B and curing agent E as resin curing agent system.
Then the water-based epoxy emulsion B and the water-based epoxy curing agent E were tested in the (0.8 to 1.2):1.0 range according to the quantity ratio of epoxy-based and active hydrogen, and the comprehensive properties of varnish were tested, and the test results were found in Table 3.
3 Comprehensive performance of varnish
test item
n
(epoxy base):
n
(vibrant hydrogen)
0.8
:
1.0
1.1. 0
:
1.0
1.1
:
1.0
1.2
:
1.0
shock resistance/cm
a
40
50
40
bending performance/mm
2
1
1
2
rowing test/stage
2
1
1
2
50 g/L NaCl (room temperature, 240 h)
foaming
no change
no change
no change

> SO
4
(room temperature, 24 h)
blistering
no change
no change
no change
50g/L NaOH
(normal temperature, 168 h)
blistering
no change
no change
blistering
salt-resistant fog (300 h)
blistering
no change

no
no change
according to Table
3,
:
n
(epoxy base)
:
n
(active hydrogen) is

0.8:1.0
, the media resistance performance of the coating film is not ideal, because of the excessive curing agent, excess amino content, resulting in a decrease in the performance of the media resistance, at the same time, excessive curing agent will also affect the mechanical performance of the coating film.
n
(epoxy base)
:
n
(active hydrogen) is
1.2:1.0
, the epoxy group excessive more, reducing the cross-link density of the coating film, thereby affecting the corrosion resistance of the coating film. Taking into account,
,
film system selected
n
(epoxy base)
:
n
(live hydrogen) for
1.0 to 1.0
.
2.2 Choice of pigment filling system
Water-based epoxy anti-corrosion coating system should choose a paint filler system with low oil absorption, chemical stability and good water resistance. Graphene has the advantages of good thermal stability, chemical resistance, good thermal conductivity and high hardness, adding graphene to the coating can improve the heat resistance, impact resistance and wear resistance of the coating. At the same time, flaky graphene in the coating drying process will be directional arrangement, overlapping each other cover, effective shielding
H
2
O, CO
2
,
Cl
-1
so that it can not directly through the scales, forced to penetrate back, slow down the penetration speed of ions, play a
maze effect", and cut off the capillary microchannel in the coating, reduce the pass rate, improve the corrosion resistance of the coating
. Aluminum tripophosphate has a
"double rust-proof" mechanism, and the de-polyphosphate root ions (P
3
O
10
5-
) have a strong co-ordination against
Fe
3 plus
, forming a passivation film with excellent corrosion resistance on the surface of the substrate to prevent further corrosion of the metal substrate. Zinc phosphate can form a formation sediment layer with
Fe
3 plus
when the metal is corroded, while zinc ions react with cathode
OH
-
,
Zn(OH)
2
is obtained to act as cathode polarization, while also being able to bond with the polar groups in the coating, improving the adhesion between the coating and the substrate and the corrosion resistance of the coating. The study used the above
3
fillers for a compounding test (see Table
4) to arrive at the best addition formula
(see Table
5
) based on a combination of mechanical and corrosion resistance. As can be seen from the results of Table
5, the addition of aluminum tripolyphosphate, zinc phosphate and graphene is too large, which will cause the fillers to form a reunion in the coating, affecting the coating performance. Scenario 4 is used in this study.
4 Filler Add Ortho Test%
Test No
Filler
Aluminium tripolyphosphate
Zinc Phosphate

1
1
3
0.3
2
1
5
0.5
3
1
8
1.0

33

0.5
5
3
5
1.0
6
3
8