2. 2
The older technology sealants used for filling gaps and joints in
building exteriors and other structures are being replaced with the
new and greener hybrid sealants using Silane Terminated Polymers
for improved performance.
The sealant in the joints needs to be flexible and compress and
elongate as the wall panels or the building sections move with
weather conditions and even traffic caused vibrations when used on
bridges and car parking buildings.
The joints can be between expensive stone panels on the outside of
new buildings , as well as inside buildings in foyers, bath rooms and
kitchens. They can be coloured to match the stone or the sealant can
be made crystal clear so it looks like there is no sealant.
The sealant needs to not change colour when exposed to sunlight and
pollution , and the hybrid sealants have better UV resistance when
compared to the older Polyurethane technology sealants.
The new hybrid sealants based on trimethoxy silane terminated
polyether's are better for applications currently using common
silicone sealants, where the oils used to make silicone sealants come
out of the sealant and stain the stone or concrete and make the face
look dirty and poor quality.
The sealants based on a low viscosity 25000 MW polyether have the
benefits of both silicone and polyurethane technology, so a true hybrid
technology that removes the disadvantages of the older products.
The trimethoxy silane capped polyether polymers are ideal for making
crystal clear sealants when thickened with fumed silica.
The trimethoxy silane capped polyether polymers can be catalysed
with a tin free catalyst package for markets where tin catalyst is a
problem..
CONSTRUCTION
SEALANTS
3. 3
STP polymers are based on the new generation
polyether polyols ,that are the same as used for PU
sealants and capped with reactive silanes that are the
same as used by silicone sealants, and this is where
the hybrid name comes from.
The polyether chain is about twice the strength of the
polysiloxane chain used in silicone sealant and lets
the sealant have better recovery from movement and
is also more compatible when mixed with plasticizers
that do not come out of the sealant.
The crosslinking of the sealant to form the one part
curing sealant uses the same Trimethoxy silane
chemistry as used by some silicone sealants. The
adhesion is excellent and in most cases with stone or
concrete there is no need for primers.
The other big advantage over polyurethane sealant is
that there are no bubbles formed when the hybrid
sealant cures.
Si polyether Polyol
OCH3
OCH3
OCH3
OCH3
OCH3
Si
OCH3
CH3O
CH3O
CH3O
Si
+ H2O
- HOCH3
OCH3
Si
OCH3 CH3O
O
The polymer is ideal for crystal clear sealants
Trimethoxy 25000MW polymer ADVANTAGES
Softest long chain polyether for lower shore A 25
sealants with high movement capacity to 20% ASTM
standards.
Enables bubble free curing at normal temperature &
humidity levels
Formulations have excellent adhesion to porous
stone and concrete panels
Excellent adhesion to aluminium with no primers
and a wash with green dimethyl carbonate solvent
Sealant has excellent UV and chemical resistance
and can be painted to match decoration changes
Sealant formulations can use the cheaper coated
PCC fillers now available to make thick sealant
Sealants are solvent and isocyanate free and
safer for tradesman and DIY consumers.
Sealants can be made in the factory with maximum
mixer temperatures of 60 degree C and low energy use
The trifunctional polymer is catalysed with low levels
of tin containing chemical like DBTDK or DBTDL.
No hazard warning labels on the sealant product
when displayed in retail stores.
Sealants can be thickened with fumed silica or
cheaper urea thickeners
Si
OCH3
OCH3
OCH3
Design of SILANE
TERMINATED Polymers
Si
OCH3
4. 4
Starting Formulation
25000 MW trimethoxy silane capped
polymer in Construction sealants
Test Results
MANUFACTURING GUIDELINES.
Construction sealants with sufficient plasticizer are easily manufactured in a low temperature process .In the first
stage the calcium carbonate and pigments are mixed with plasticizer such as DIDP or 2000MW diol . These are
dispersed under high shear and high vacuum to get to 60 degree Centigrade. .Some inexpensive dry methanol can
be added to help remove moisture that is on the particle surface and comes off easily. At 50 degree C when moisture
is about 500 ppm the more expensive vinyl silane is added to remove the harder to get moisture locked inside the
calcium carbonates.
Once the powders are dry with the DIDP or other plasticizers ,the resin can be added safely under a dry nitrogen
blanket .Then the thickener and other additives can be added .The catalyst with vinyl silane is the final addition
before the sealant is filled into cardboard cartridges or sausage packs that are lined with aluminium foil.
The sealants made with trimethoxy terminated polymer are very reactive , need low levels of tin catalysts and it is not
recommended they be filled into thin wall HDPE cartridges.
Material Parts by Weight
1. Prepolymer Trimethoxy 25000MW 100
2. Plasticiser DIDP or 2000MW Diol 70
3. Filler Omyacarb 2T 170
4. Pigment TIO2 20
5. Drying Agent A171 and dry methanol 5
6. Thixotropic Agent Aerosil R202 10
7.Stabilizer and UV
inhibitor
Tinuivin 765 and Irganox 1076 2
8. Adhesion Promoter Secondary amino silane KBM603 2
9. Catalyst DBTDL or DBTDK 0.5
Total 379.5
Standard
Tack free time 60 minutes
Shore A penetration 34 ISO 868
Tensile strength at break 1.2 Mpa ISO 37
Elongation at break 320 percent ISO 37
5. 5
Sealant applications
The main requirements for exterior sealants are:
• Low modulus even at low temperatures
• Excellent UV resistance
• High colour stability and no colour change
• Good adhesion to porous and non-porous substrates
• High tear resistance
• Paint ability when needed
• Resistance to cleaning procedures
• Bubble free Curing
•No surface tack that gathers
dust and dirt
•Hybrid sealants based on Trimethoxy silane
terminated polymers meet the above
requirements.
Construction joint or gap sealants have specific requirements:
•Good adhesion to damp or dry porous and non-porous
substrates
•Compatibility to various substrates including plastics, paints
and coatings
•High colour stability and UV resistance with no chalking
•Good dust and pollution resistance
•Paintability when concrete is painted or redecorated
Polymer for Adhesive requirements
Adhesives for hard floors such as sports arenas require:
•High mechanical strength and recovery ,low creep.
•High vibration resistance
•Good chemical resistance
•Excellent adhesion properties
•.Moisture resistance
•Hard sports surfaces such as these are placed on concrete
slabs and the products required are :
•.moisture resistant membrane based on 25000 MW Trimethoxy
resin
•.adhesive layer based on 16000 MW Trimethoxy resin
•.expansion joints in the wood floor based on above construction
sealant.
6. 6
Adhesives based on trimethoxy 16000 MW
polymer
Starting formulation
Properties
Manufacturing Instructions
The basic manufacturing process is the same low temperature method as for the construction sealant above where
the PCC and GCC blend is dried with the plasticizer before addition of other additives. As floor adhesives are thinner
and there is a need to spread easily, the viscosity and slump can be adjusted by the amount of PCC added to a
coarser particle GCC like Omyacarb 5. Other thickeners are not needed.
As floor adhesive are normally sold in 15 litre pails, It is normal to adjust the open time with vinyl silane and a little
dry DMC solvent for the applicator and temperature conditions on application.
Where fast cure adhesive is needed, we recommended to add a catalyst pack as an additive addition that is mixed
into the drum before application.
.
Material Parts by Weight
1. Prepolymer Trimethoxy 16000 MW 100
2. Plasticiser Diisodecyl phthalate 80
3. Calcium carbonates PCC and Omyacarb 5 blend 200
4. Pigment Iron oxide brown 2
5. Drying Agent Silquest A-171 4
6. Stabilizers Tinuivin 765 and Irganox 1076 4
7. Adhesion Promoter Secondary amino silane KBM603 2
8. Catalyst DBTDL(also fungal agent) 2
Total 394
Standard
Tack free time (min) 50 adjust with A171
Shore A hardness 45 ISO 868
Tensile strength (MPa) 2.5 ISO 37
Elongation at break (%) 250 percent ISO 37
7. 7
Adhesives for buildings and
Saunas
The adhesive needs to be elastic and allow some movement of the wood
floor or wood clad wall to reduce the noise that is generated by walking
in hotel foyers or department stores. and running of sports people in
sports arenas.
The careful formulation for hardness and recovery of the adhesive
softens the impact of walking and running on the hard floor surface
and makes sport more comfortable and less strain on the knees
and ankles of sports people.
.For Bonding of furniture and other wood joints such as stairs, much
harder adhesives are needed with higher shore A hardness and less
elongation .This can be achieved by adding 25 to 50 percent of shorter
chain triol trimethoxy polymer, which is lower viscosity with a higher
crosslinking density. The use of 100 percent PCC filler also makes the
adhesives harder , yet still allows some movement capacity.
A significant innovation is the ability to use Trimethoxy silane terminated
resins as a clear adhesive with DIDP and fumed silica like Aerosil R972
as the only thickening agent that also gives the polymer strength . This
lets the bonding of expensive timbers where the adhesive fills the
expansion joints or seams and is not detracting from the wood
appearance.
Wood is a particular problem as a construction material as it absorbs
moisture and wants to move and expand. so adhesives need to allow for
this movement and softer sealant is used in expansion joints around the
Perimeter.
For Sauna applications high humidity causes mould and fungus
growth ,and it is advised that the sealants and adhesive use
DBTDL catalyst as this also at the same time provides fungal
protection at the adhesive face with the wood surface.
Advantages of adhesives
based on Trifunctional 16000
MW polymer
8. Please Contact vladimyr@wolantech.com for
discussions on licensing options for the low viscosity
polymers suitable for Construction applications shown
above.
