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Formulating
and Processing Guide
The
information here is given as a guide to existing and potential users
of Plexinate and represents just a little of the in-house research
and development conducted by the Plexinate company. Please contact
us with any questions regarding your existing or potential application.
Use
the quicklinks below to jump to a particular section.
HAND
LAY-UP/ SPRAY-UP
Introduction
MEKP Room Temperature Cured Laminating Resin
UV Curing Laminating Resin
PULTRUSION
Introduction
P100/P200 Combinations
Copper Naphthenate for Thick Section Curing
13/16ths( 20.6 ml) Diameter Rod Formulation
Filler Free Pultrusion
Highly Filled Systems for Economy
Pultruding Low Cost Tube
HAND LAY-UP/ SPRAY-UP
Introduction
Plexinate
P100 may be formulated for hand lay up in much the same way as conventional
unsaturated polyester or vinyl ester. Plexinate P100 will chemically
bond to the uncured surface of polyester gelcoats and in turn will
leave an uncured surface for subsequent lamination, even when UV
curing is used.
MEKP
Room Temperature Cured Laminating Resin
Formulation
100.0 pts Plexinate P100
.5 pts Cobalt Octoate 6% (promoter)
.2 pts Byk A515 (air release agent)
.4 pts Benathix or Aerosil (thixotroping agents)
Mixing Instructions
Disperse ingredients in order of formulation until free from lumps.
Directions for Use
Stir in 1-2% MEKP (or cumyl hydroperoxide for better surface cure)
and mix thoroughly. Resin can then be rolled onto glass or directly
onto polyester gelcoat. Adhesion to gelcoat is outstanding. Potlife
is about 15-30 mins @25oC depending on initiator addition. This
formulation is also suitable for spray application with a chopper
gun.
UV Curing Laminating Resin
Formulation
100.0 pts Plexinate P100
.1 pts Irgacure 819 (photoiniator)
.2 pts Byk A515 (air release agent)
.4 pts Benathix or Aerosil (thixotroping agents)
Mixing Instructions
Disperse ingredients in order of formulation until free from lumps.
Directions
for Use
Lay onto fibreglass and roll out thoroughly. When laminate is ready
to be cured expose to UV light. Sunlight is excellent but common
low power tanning lamps are a more practical and convenient indoor
method.
PULTRUSION
Introduction
Plexinate requires no modifications to either equipment or processing
for use in pultrusion. It is compatible with common polyester glass
sizing and coupling agents. It is compatible with common fillers
(calcium carbonate, clay, ATH) and uses the same peroxide initiators
for curing as conventional unsaturated polyesters. (Perkadox 16,
Alkenox p100, TBPB, BPO, etc.) Polyester pigment pastes are also
suitable for use with Plexinate, as are the common internal release
agents. Plexinate can be used with a normal wet out bath or directly
injected into the die.
P100/P200 Combinations
P100 can be use either on it’s own or with P200. P200 is added
at between 10-30% on P100 depending on the part. P200 is especially
useful at aiding overall processability and can eliminate both internal
and external cracking as well as improving surface quality.
Copper Naphthenate for Thick Section Curing
A recent development with Plexinate has been the successful utilisation
of copper naphthenate for the supression of peak exotherm in thick
pultruded sections. Copper naphthenate is interesting in this process
because it acts as both a promoter and exotherm supressant in combination
with Perkadox 16 or Alkenox p100. It does however, interact with
other components in the formulation such as fillers and mould release
agents. Sometimes this may result in undercure and require the use
of additional alternative initiators like TBPB. Generally the part
will require more heat down the die length to cure, and it is this
feature that leads to elimination of a runaway exotherm resulting
in internal and external cracking.
When experimenting with copper naphenate in the first instance,
stick to the formulation below as we have proven this to work and
know that the interaction of these raw materials lead to full cure
without runaway exotherm. Copper naphthenate is usefull for unidirectional
parts thicker than 10mm and filler free parts. Copper naphthenate
is sold at many hardware stores as a rope, wood and canvas preservative.
It will often be at about 10% in mineral spirit. The addition level
we have found effective is about 1 part of this mixture to 100 parts
of resin, resulting in an effective addition of 0.1%. Alternatively,
copper naphthenate may be purchased directly through a manufacturer
or distributer. They will normally quote the effective copper content
rather than the copper naphthenate content. Use this mixture to
end up with an effective copper level of 0.01% to 0.02% on resin.
13/16ths(
20.6 ml) Diameter Rod Formulation
100 parts Plexinate P100
10 parts Plexinate P200
1 part Copper Naphthenate 10% solution
30 parts Filler (Omyacarb 3, Calcium carbonate)
1 part Perkadox 16
1 part Mould Release (Axel INT-PS125)
108 ends. Die settings @ 135/145/145oC.(275/293/293oF) No internal
or external cracking. Line speed of .550 meters / minute. Full internal
and external cure with Barcol reading of 70. Die length was 4 feet.
(1.22 meters)
The gel onset temperature of this formulation is 110oC (230oF) and
the peak exothem is below 170oC (338oF). These temperatures were
determined by feeding a thermocouple through the die with the part.
The initial temperature rise from 110-130oC (230-266oF) is fairly
rapid with a slow rise then to 150oC (302oF) approx. where it holds
before slowly rising again to 160oC (320oF) approx. It is the slow,
controlled ramp up of the part during cure that keeps the internal
and external part temperatures closer together thereby preventing
internal and external cracks.
Filler Free Pultrusion
Plexinate can be pultruded without any filler at all. This results
in a fantastic increase in overall part strength. Generally a higher
glass content is required to compensate for the absence of filler
during processing. Copper naphthenate is usefull here too, in contributing
to an early gel and preventing a runaway exotherm. Becauce the filler
is absent, there is obviously no interaction between it, the copper
naphthenate and the Perkadox 16. It is therefore necessary to add
a small amount of TBPB to finish the reaction. Please see the formulation
below for filler free rod. For very small filler free profiles,
copper naphthenate is unnecessary and a more conventional initiator
system may be employed.
8mm
Filler Free Rod Formulation
100 parts Plexinate P100
30 parts Plexinate P200
1 part copper naphthenate (10% solution)
0.5 parts Perk 16
0.5 parts Trig C
1 part Mould Release (Int 125)
18-20 ends. Die settings @ 130/130/130oC.(266/266/266oF) No internal
or external cracking. Line speed of 1.1 meters (44 inches) / minute.
Full internal and external cure with Barcol reading of 70. Die length
was 3 feet.(.914 meters)
The flexural bending strength of this rod was in excess of 30% greater
than an analogous filled Plexinate rod.
Highly Filled Systems for Economy
Plexinate P100 can accept large amounts of filler and still remain
at an acceptable viscosity for pultrusion. Up to 120% on resin for
even smaller particle sized filler. From the work we have done,
these highly filled systems are still stronger than analogous, less
filled polyester parts. The economics work out in favor of this
approach, even when taking into account the high specific gravity
of most fillers and calculating on a volumetric basis.
Pultruding Low Cost Tube
Die Dimensions
OD 1.265 inch ID 1.090
48 inches long
Reinforcements
36 ends of 4400 Tex continuous roving
Internal and external continuous strand mat (Owens Corning type
8146)
Xanax surface veil
Resin Formulation [Parts By Wt]
Plexinate P100 [100.0]
Perk 16 [0.5]
Trig C [0.5]
Mould Release (Axel Int 125) [1.0]
Filler (Omyacarb 3) [100.0]
Pigment Paste [5.0]
Processing
Die Settings 170 /170/170 oC
Line Speed 66 inches / min
Surface Appearance Glossy
Barcol Hardness 70
Flexural Strength Comparison with Competitive Polyester Tube
This test measures the amount of weight supported by the tube in
the middle of a 45 inch span before failure.
Competitive Polyester Tube 352 lbs
Plexinate P100 Tube 495 lbs
Cost Comparison
The Plexinate tube costs only about 10% more than the competitive
polyester tube because of the higher filler level tolerated by the
Plexinate polyurethane without detrimental effects. The polyester
tube used a low cost ortho priced at around $0.75 lb with a filler
level of 50% on resin. The Plexinate cost was based on standard
8 drum delivered cost.
The cost benefits of increased speed and lower scrap rates by the
Plexinate were not considered.
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