bronchitis英语科技论文写作结课论文

2021年1月20日发(作者：簿)



英语科技论文写作结课论文


The Preparation and Research Of
Epoxy Resin Modified Water-bone
Polyurethane Emulsion










1. Introduction

There are various types of raw materials for synthetic water-bone polyurethane
emulsion, including not only main raw materials such as isocyanates of polyurethane
resin
、
polyhydric alcohols or polyamine , but also auxiliary raw materials like chain
extender
、
catalytic agent
、
neutralizer. By different synthetic processes and compound
designs
we
can
produce
water-bone
polyurethanes
with
different
properties
[1]
.
The
great advantage of water-bone polyurethane is using water as dispersion medium, the
method we use to compose water-bone polyurethane is self-emulsification method, as
it need not to add emulsification. As the epoxy resin has many excellent properties:
great binding power and intensity, and it has hydroxide radical which can react with
–
NCO
in
polyurethane
then
reach
the
aim
of
modifying
polyurethane
[2]
.
This
modification
overcomes
the
polyurethane
’
s
shortcoming
to
a
large
extent
[3]
.
In
our
experiment
,
we
discussed
the
temperature
and
time
of
pre-polymerization
、
the
temperature of emulsification
、
the R value
、

the addition of DMPA
、
the molecular
weight of PEG
、
the addition of BDO and EDA, then make sure the best matching.
Afterwards we use epoxy resin to modify PU, and discussed the addition of DMPA
、
the
different
kinds
of
epoxy
resins
and
the
addition
to
affect
the
properties
of
water-bone PU, then determine the best matching of the addition of DMPA and epoxy
resin which enhanced the properties of PU the greatest degree
[4]
.
2. Experiment




We first studied the reaction temperature, reaction time on the properties of
water-bone polyurethane emulsion. Then in the best reaction temperature and time we
discussed
different
ratio
of
raw
materials
affected
the
water-bone
polyurethane
emulsion
’
s appearance
、
storage stability and the waterproof
、
the mechanical property
and the heat endurance of the coating. From this we obtained the best formula.
The
preparation
of
epoxy
resin
modified
water-bone
polyurethane
emulsion
mainly
divided
into
two
stages[5]:
The
first
stage
is
pre- polymer,
and
the
main
reaction is the
–
NCO in MDI react with
–
OH in PEG to produce Carbamic acid ester
bond, when added DMPA then
–
COOH added, afterwards added BDO to increase the
length of the chain, the last adding the
–
OH to bring in the epoxy groups; The second
stage is
neutralization emulsification. We
cooled the pre-polymer
to
30
°
, then add
TEA
to
neutralize
–
COOH,
followed
under
the
action
of
high-speed
shearing
join
EDA aqueous emulsion, among this the epoxy ring opening to
–
OH. At last the epoxy
resin modified water-bone polyurethane emulsion made.
The picture in the following is the analysis of FTIR of the epoxy
、
the water-bone
polyurethane emulsion and the epoxy modified water-bone polyurethane emulsion.