Download The story of V

S TA C
Industrial Coatings
The story of V
V : Vinyl-Ester systems: 1-component with initiators
Vinyl-Ester systems: 1-component free-radical catalysed co-polymerisation reaction of Vinyl-Ester resins.
The reaction is started with initiators, called “catalyst” and “accelerator”. The “accelerator” activates the
“catalyst” (breaks it in radicals) and the latter initiate the cross-linking co-polymerisation of the vinyl-ester
pre-polymers with styrene. They form a 3D-PEPS (three dimensional polyester-polystyrene) matrix.
Hmmm..? : You can compare it with a wood fire. You need a match and a matchbox. Rub the match over
the matchbox to put it on flame. Insert the burning match in the woodpile. If the wood pieces
are proportional, well-arranged and not (too) wet, they will catch fire and the pile will burn
completely. If it’s colder you use a bigger flame.
Vinyl-Ester systems have the highest chemical-thermal resistance (even higher than polyesters) because they
do not have left reactive groups in the matrix: no reactive end groups (-OH, -COOH), no unreacted carboncarbon double bonds (= unsaturated, (vinyl group = ethenyl group = unsaturated end-group)).
Vinyl-Ester (VE) systems, like most resin systems, shrink during the curing (polymerisation). The volume of
the solid form is smaller than the liquid form. VE systems, like unsaturated polyester (UP) and epoxy (E)
systems, are not very elastic and thus the shrink creates a lot of internal tension (stress). The thicker the layer
the more significant this becomes. That’s why often in thick systems shrinkage joints are made to avoid it
will burst during the curing. If it doesn’t burst during the curing, a lot of internal tension is present, so a
thermal and/or mechanical chock will make it crack. Mostly the problem is “solved” by inserting fillers
(quartz, mats, fibers, pigments,…) into the resin to decrease the relative portion of the resin and to proportionally decrease the shrinkage. Nevertheless the systems stay under serious tension.
STAC-V Systems: STAC managed to solve this big problem by developing a tailor made technology, modifying the formulation and curing process, to make it shrink-free. This was a major step forwards and the
main reason of creating the company.
How is it made? : If you really want to know, hold tide and start reading!
How is it made?
Vinyl-Ester resins: mixture of mainly vinyl-ester pre-polymers and styrene.
Vinyl-Ester pre-polymers: esterification of poly-epoxy resins with unsaturated monocarboxylic acids.
Epoxy resins: mixture of mainly poly-glycidyl-ether pre-polymers.
Remark: mostly “poly” is “di”.
Poly-glycidyl-ether pre-polymers: 2-component addition reaction between polyols and epichlorohydrin.
Polyols: mostly aromatic, mainly:
CH3
Bisphenol-A = BPA = 2,2-bis(4-hydroxyphenyl)propane
=
HO–
–C–
CH3
–OH
H
Bisphenol-F = BPF = bis(4-hydroxydiphenyl)methane
=
HO–
–C–
H
OH
Novolac = “poly-BPF” = phenol-formaldehyde prepolymer
Let S TA Ckle those corrosion problems!
=
–OH
OH
CH2
CH2
The story of V
Edition: January 2017 (cancels and replaces the preceding ones)
n
Page 1 of 6
S TA C
Industrial Coatings
epoxide group
= oxirane group
O
H2C–CH–CH2–Cl
Epichlorohydrin: = ECH = chloromethyloxirane = glycidyl chloride =
= glycidyl group
Epoxy resins: Poly-glycidyl-ether pre-polymers = addition of polyols and epichlorohydrin.
Most common reaction:
bisphenol-A
–C–
CH3
di-epoxy resin
O
CH3
(n+1) HO–

epichlorohydrin
+
–OH
(n+2) H2C–CH–CH2–Cl
+
↓ + NaOH
CH3
–C–
CH3
O
H2C–CH–CH2–O–
OH
–O–CH2–CH–CH2–O–
n
CH3
–C–
CH3
O
–O–CH2–HC–CH2
= glycidyl-ether
+ NaCl + H2O
Example: n =0 = BADGE = bisphenol-A di-glycidyl-ether
Unsaturated monocarboxylic acids: mainly vinyl monocarboxylic acids.
Hmmm..? : Vinyl is a molecule that contains at one end a double bound: R-CH=CH2
Monocarboxylic acid is a molecule containing one carboxyl group: R-COOH
Vinyl monocarboxylic acids: mainly:
H
Acrylic acid
=
CH2=C–COOH
Methacrylic acid =
CH2=C–COOH
CH3
Vinyl-Ester pre-polymers: esterification of epoxy resins with unsaturated monocarboxylic acids.
Epoxy resin
O
CH3
–C–
H2C–CH–CH2–O–
OH
–O–CH2–CH–CH2–O–
CH3
Simplified:

vinyl monocarboxylic acid
+
x
O
O
H2C–CH–R–HC–CH2
n
DVDE (divinyl-diester) prepolymer
CH3
–C–
O
–O–CH2–HC–CH2
O
+ CH2=CH–C–OH
CH3
O
+
2x CH2=CH–C–OH
↓
OH
OH
O
O
CH2=CH–C–O–CH2–HC–CH–R–HC–CH2–O–C–CH=CH2
Let S TA Ckle those corrosion problems!
= vinyl-ester group
The story of V
Edition: January 2017 (cancels and replaces the preceding ones)
Page 2 of 6
S TA C
Industrial Coatings
Vinyl-Ester resins: mixture of DVDE (divinyl-diester) pre-polymers and vinyl monomer, mainly styrene.
OH
OH
O
O
CH2=CH–C–O–CH2–HC–CH–R–HC–CH2–O–C–CH=CH2
H
+n
H
H
CH=CH2
H
H
Simplified:
Vinyl-Ester systems: 1-component systems, based on Vinyl-Ester resins, resulting from a free-radical catalysed co-polymerisation reaction of DVDE (divinyl-diester) pre-polymers and styrene. The reaction is started
with initiators, called “catalyst” and “accelerator”.
Initiation
The “accelerator” activates the “catalyst”. The “catalyst” is a peroxide which is broken in 2 by the “accelerator” to create 2 molecules with an oxygen with a free electron in surplus, commonly called “free radical”.
Initiation, part 1:
R−O−O−R
accelerator
2 R−O°
These unpaired electrons (on the radicals) will be quite discontent with being alone and still want to be
paired. If they can find ANY electron to pair up with, they will do so. The carbon-carbon double bond in a
vinyl monomer, or in a DVDE, has a pair of electrons which is very easily attacked by the free radical. The
unpaired electron, when it comes near the pair of electrons, can't help but swipe one of them to pair with
itself. This new pair of electrons forms a new chemical bond between the initiator fragment and one of the
double bond carbons of the vinyl monomer or DVDE. The other electron of the double bond (vinyl group)
attaches to the other carbon atom of a double bond (the C that is not bonded to the initiator fragment).
Now we have a new free radical.
This two steps process, namely first the decomposition of the initiator into a pair of free radicals and secondly
the reaction of the free radical with present vinyl groups (double bonds) from styrene or DVDE, is called
“initiation” of the free radical (co)polymerisations.
Chain propagation
The new radical, created in the initiation step, reacts with another vinyl monomer or DVDE in the exact
same way as the initiator fragment did. Because we keep remaking a radical, which recombines (reacts) with
a double bond (vinyl group) either from a DVDE or a styrene, we can keep adding more and more vinyl
monomers or DVDE’s, and build a long chain of them. Self-perpetuating reactions like this one are called
chain reactions.
Termination
The polymer chain propagation will tend to terminate. Radicals are unstable, and eventually they are going
to find a way to become paired without generating a new radical. Then the chain reaction will come to a
halt. This happens in several ways.
The simplest way is that the radical sites of two growing chains find each other. The two unpaired electrons
then join to form a pair and a new chemical bond in made, joining their respective chains. This is called
coupling or recombination.
Another way in which our unpaired electrons can shut down the polymerization is called disproportionation.
This is a rather complicated way in which two growing polymer chains solve the problem of their unpaired
electrons. The mechanism takes place through transfer of a hydrogen atom from one polymer chain radical
to another.
Let S TA Ckle those corrosion problems!
The story of V
Edition: January 2017 (cancels and replaces the preceding ones)
Page 3 of 6
S TA C
Industrial Coatings
O
O
CH2=CH–C–O–R’–O–C–CH=CH2
Initiation, part 2:
+
R−O°
R
O
O
O
CH2−C°H–C–O–R’–O–C–CH=CH2
Chain propagation:
CH=CH2
R
O
O
O
CH2−CH–C–O–R’–O–C–CH=CH2
CH−CH2
CH=CH2
R
O
O
O
CH2−CH–C–O–R’–O–C–CH=CH2
CH−CH2
CH−CH2
Cross-linking:
styrene
~ ~
~ ~
styrene
styrene
styrene
styrene
DVDE
styrene
styrene
DVDE
styrene
styrene
~ ~
~ ~
styrene
styrene
Styrene bridge
styrene
~ ~
styrene
~ ~
styrene
styrene
styrene
styrene
styrene
DVDE
styrene
~ ~
styrene
styrene
styrene
~ ~
DVDE
styrene
styrene
Let S TA Ckle those corrosion problems!
The story of V
Edition: January 2017 (cancels and replaces the preceding ones)
Page 4 of 6
S TA C
Industrial Coatings
Vinyl-Ester resin types
Solution in styrene of pre-polymers, e.g.:
BPA VE:
bisphenol-A VE
vinyl-esterified epoxidised bisphenol-A
NOV VE:
novolac VE
vinyl-esterified epoxidised novolac
BPA VEU:
bisphenol-A VEU
modified vinyl-esterified epoxidised bisphenol-A urethane
Initiators: “Accelerator” and “Catalyst” types
Accelerators: Activators of the “Catalysts”, vb.:
Cobalt salts:
cobalt naphthenate
cobalt octoate (=cobalt(II)-2-ethylhexanoate)
Amines:
DMA
DEA
DMPT
dimethylanaline
diethylanaline
dimethyl-para-toluidine
UV light
Heat
Catalysts:
Initiators of the co-polymerisation, mostly organic peroxides, e.g.:
Organic peroxides:
MEKP
AAP
CuHP
BPO
methyl ethyl ketone peroxide
acetyl acetone peroxide
cumene hydroperoxide
dibenzoyl peroxide.
Ps: If you want to know the formula’s: see appendix.
You want to know the full story?
See
“Synthesis of 3D-PEPS according to 2 related pathways.”
Let S TA Ckle those corrosion problems!
The story of V
Edition: January 2017 (cancels and replaces the preceding ones)
Page 5 of 6
S TA C
Industrial Coatings
Appendix: formulas of initiators
Accelerators (activators of the “Catalysts”)
Cobalt salts:
cobalt naphthenate
O
C
O
cobalt octoate (= 2-ethylhexanoate)
O
-
C
+2
Co
-
O
O
+2
Co
-
O
C
C
O
O
Amines:
DMA (dimethylanaline)
N
DEA (diethylanaline)
CH3
N
CH3
CH2−CH3
CH2−CH3
DMPT (dimethyl-para-toluidine)
H3C
N
CH3
CH3
Catalysts (initiators of the co-polymerisation)
Peroxides:
MEKP (methyl ethyl ketone peroxide)
AAP (acetyl acetone peroxide)
CH3
CH3
HO−O−C−O−O−C−O−OH
CH2−CH3
CH3−CH2
O HO
CH3−C−C−C−CH3
O
O
CH3−C−C−C−CH3
O HO
CuHP (cumene hydroperoxide)
CH3
C−O−OH
CH3
Let S TA Ckle those corrosion problems!
BPO (dibenzoyl peroxide)
O
C−O−O−C.
O
The story of V
Edition: January 2017 (cancels and replaces the preceding ones)
Page 6 of 6