Advances have been made in the study of the durability of polyurethane/polyurethane coatings

Progress in the study of durability of polyurethane
/
polyurethane coating
Lin Jing, Song Yulong, Car Kaiyuan, Ma Liang
(Qingdao University of Technology School of Civil Engineering, ShandongQingdao
266033)
Recept:
Polyurethane
/
Polyurethane coating is one of the most commonly used coatings in the research of protective coating technology, as a new type of
elastomer material, with fast reaction, instantaneous curing, ultra-strong wear resistance, strong corrosion resistance and other characteristics
, and is moving towards
low cost, high performance and
environment-friendly
direction
. The excellent
of
/polyurethane coating itself has a significant effect on the durability of concrete structures. The good
durability
polyurethane coating has been widely concerned since its inception and has been widely
china
. This paper mainly summarizes the current research status of polyurethane
/
polyurethane coating anti-chloride ion permeability, corrosion resistance and aging, and briefly introduces the relevant models on durability that have been established so far.
key words:
polyurethane
/
polyurethane coating, durability, anti-chloride ion penetration, corrosion resistance, aging
0
Introduction
Polyurethane
/
Polyurethane coating with its own excellent corrosion resistance, impact resistance, wear resistance and aging resistance and other properties, in the protection process, fully demonstrated the
0
VOC
emissions
,
in line with the requirements of the national environmentally friendly materials,
this new type of green
material
has been widely used in the field of concrete coating protection
,
has
been used in a variety of large-scale
.
spray polyphosphate elastomer technology in the
20th century
1990s
90s

in the
The first successful research and development in the United States, China's polypropyl
/
polyurethane coating research started late,
1995
, yellow microwave and so on began the research and development of polyonium technology, after more than ten years of continuous development, polypropyl materials in its application area has made a great breakthrough.
as an organic coating, polyurethane
/
polyurethane coating
also faces a variety of corrosion and aging problems in
service
environment. Therefore, the aging behavior
, anti-chloride ion penetration and media corrosion of polyurethane
/
polyurethane
coating can be studied to better predict the service life of polyurethane coating
. At present, polyurethane
/
polyurethane coating has been successfully applied to large-scale construction projects such as the Beijing-Shanghai high-speed railway, the Hong Kong-Zhuhai-Macao Bridge, the Qingdao Hangzhou Bay and the Gelzhou Bay Bridge.
1
Durability Study
1.1
Anti-chloride Ion Permeability Study
Yellow Microwave, etc.
Permeation of polycetamol and polyurethane-coated concrete antichloride ions through natural immersion and wet and dry circulation
The performance was studied, and the results of the
test
of
120 d
showed that the concrete
D
a
coated with polysaccharged concrete was

67.9%
, polyurethane-coated concrete
D
a
reduced
67.8%


;
test
results show that the polyester-coated concrete
D
a
is
76.7%
less than uncoated concrete and polyurethane-coated concrete is reduced
D
a
76.6
%
. It can be seen that both polyurethane and polyurethane can play a good antichloride ion penetration performance on concrete.
Sun Congtao, etc.
conducted anti-chlorine ion permeability, breathability and permeability tests on composite coatings, membrane-forming epoxy coatings, permeable silane and membrane-forming polyurethane coatings, and the results showed that different types of anti-chloride ion permeability were found. The effect of the coating is different, among which, the effect of the film-forming coating and the composite coating is obviously better than that of the permeable coating, the effect of the poly-ion coating is the most excellent, and the diffusion coefficient of chloride ions is reduced by
95.8%
to
97.2%
.
Bo Zhongwei
compared the anti-chloride ion penetration properties of polycarbonate, epoxy and chlorinated rubber-coated mortar in
3.5%
sodium chloride solution, and the results showed that after soaking
90d
, polypropyl, epoxy and chlorinated rubber were found in
90d
compared to blank samples.

Cl
-1
content at the depth of 6
mm
is
3.41%
,
4.64%
and
5.72%
, respectively, so that the anti-chlorine ion penetration performance of the polycarp coating is significant than that of the other two coatings.
Yang Lin
, etc.
using natural immersion and
RCM
method to spray polychloride anti-chloride ion penetration performance, the results show that: painted
80 μ
m
of fatty polysaccharide concrete and aromatic polysaccharide concrete in natural immersion
100
,
D


49.39%
and
44.14%
, respectively, and brushing increased from
80 μ
m

the μof the above two polycarp-coated concrete in the rapid chloride ion penetration test, the adipose poly-coated concrete
D
a
decreased by
25.19 percent
, aromatic polyp coated concrete
D
a

53.80%
reduction, and it can be seen that the anti-chloride ion penetration performance of the adipose polycyclyc coating is better than that of the aromatic polycyclysis coating.
1.2
Media Corrosion Study
Lue Equality
the resistance of polycarbonate coating to ion corrosion by seawater immersion, sulphuric acid immersion and sodium hydroxide immersion was studied and
The SEM
further observed the morphological characteristics of the surface after the aging of the polycarp coating, and the results showed that after the sea water soaked
180 d
, the extrusion strength of the polysaccharine coating decreased by only
After 4%
, when sulphuric acid is soaked
60 d
, the stretch strength of the coating is reduced by
30%
, but remains at
15 M After
holes appeared in the coating surface above Pa, sodium hydroxide was soaked
60 d
, and the stretch strength was reduced by
25%
and remained at
17MPa
above, it can be seen that the sea water has little effect on the performance of the coating, while the corrosion resistance of the polysaccharide coating is reduced under the immersion of sulphuric acid and sodium hydroxide.
Li Haiyang and other
studied and analyzed the corrosion resistance of epoxy cloud iron
,
polyurethane
and polyurethane
coatings under the immersion of
5% NaCl
solution. The results showed that after soaking
90 d
, the loss rate of polyurethane, epoxy cloud iron and polyurethane coating was
4.2%
and
19.1% respectively


16.7%
, adhesion decreased
17.65%
,
52.94%
and
55.11 %
;
SEM
image found that the polyurethane coating appears whitening phenomenon, epoxy cloud iron coating appears slight cracks, while the polyurethane coating remains well attached, the coating structure remains tight, the metal substrate appears slightly corroded, Good protection.
luping
and other
through media immersion
-test
to the bridge support protection material corrosion-resistant performance of the study, the results show that
: after
90 d

5%
sulphuric acid,
5%
sodium hydroxide and
3.5%
sodium chloride soaked, polycarbonate coating stretching Intensity decreased by
13.73%
,
8.13%
and
12.44%
, respectively, with small changes in coating hardness The results of theFT-IR
test show that only a small part of the surface chemical bonds break after the aging of the
polycarp coating, but the internal structure of the
coating
does not change much
, and the coating still has strong corrosion resistance.
Liu Peili, etc.
studied the media resistance of aromatic polyphosphonate, and the results showed that alkali had little effect on the strength of polycarbonate, and that high concentrations of acid had a great effect on the extrusion strength of polysaccharide coating, which was completely out of performance after soaking
2
d
in
50%
of nitric acid.
Ping Lu

a polytethandonol polyurethane polyurethane coating for a single
Na
C
l
solution immersion, load and
Na
C
l
solution immersion The performance of concrete was studied, and the results showed that the content of chlorine ions in coated concrete was significantly higher than that of chloride ions in single
Na
C
l
solution immersion under the joint action of load and

Na
C
l
solution
immersion. 1.3
Aging Performance Study
Yellow Microwave,
Using
FT-IR
,
DSC
and other
-test
methods, the durability of
pure polypropyl re-corrosion coating in the ocean atmosphere was studied, and the results of
test
showed that: natural exposure in the outdoor environment
6 after d
, the gloss of pure polyazine heavy anti-corrosion coating changed greatly, decreasing by
94.53%
, and the coating's 000 h
was basically unchanged;
FT-IR
,
DSC
The test results show that the chemical bonds of dye molecules on the surface of the coating break, fade or darken only in the two environments of natural exposure and artificial accelerated aging, and the molecular structure inside the coating remains stable and the coating maintains good protective properties. Forking
tests
on pure polyproxyl heavy anti-corrosion coatings that are naturally exposed to
6
months in open seawater pools show that pure poly-poly-poly-heavy anti-corrosion coatings are more effective than other heavy anti-corrosion coatings.
He Yushan
studied the performance of bridge steel strands and support protective coatings under natural sun exposure, UV artificial accelerated aging and corrosion media immersion, and the results showed that the protective performance of polysaccharina coatings was the best.
Rue Equality
systematically studied the accelerated aging behavior of polytianmen's gyrosine polycycline coating through
SEM
,
AFM
and
FT-IR
methods