U.S. patent application number 14/152513 was filed with the patent office on 2014-07-17 for air and water barrier.
The applicant listed for this patent is Dow Corning Corporation. Invention is credited to William Johnson, Andrea Watts.
Application Number | 20140196396 14/152513 |
Document ID | / |
Family ID | 50031583 |
Filed Date | 2014-07-17 |
United States Patent
Application |
20140196396 |
Kind Code |
A1 |
Watts; Andrea ; et
al. |
July 17, 2014 |
Air And Water Barrier
Abstract
A method for decreasing the vapour permeability of a water and
air barrier treated substrate that includes treating the substrate
with a liquid applied, vapour permeable air and water barrier
coating composition comprising a cross-linked polysiloxane
dispersion composition.
Inventors: |
Watts; Andrea; (Alexandria,
VA) ; Johnson; William; (Midland, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dow Corning Corporation |
Midland |
MI |
US |
|
|
Family ID: |
50031583 |
Appl. No.: |
14/152513 |
Filed: |
January 10, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61905465 |
Nov 18, 2013 |
|
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|
61824152 |
May 16, 2013 |
|
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61751428 |
Jan 11, 2013 |
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Current U.S.
Class: |
52/408 ;
524/425 |
Current CPC
Class: |
C08K 3/01 20180101; C08L
2312/08 20130101; C08K 2003/265 20130101; C08K 2003/2241 20130101;
C08K 3/26 20130101; C08L 83/04 20130101; C09D 7/61 20180101; C09D
183/06 20130101; C08G 77/16 20130101; C08K 5/06 20130101; C08K
2003/2237 20130101; E04B 1/66 20130101; C08K 5/0008 20130101; C08K
3/36 20130101; C08L 2312/00 20130101; E04C 2/44 20130101; C08L
2201/52 20130101; C09D 183/04 20130101; C09D 183/04 20130101; C08K
2003/265 20130101; C08K 2003/2237 20130101 |
Class at
Publication: |
52/408 ;
524/425 |
International
Class: |
C09D 7/12 20060101
C09D007/12; E04B 2/00 20060101 E04B002/00 |
Claims
1. A method for decreasing the vapour permeability of a water and
air barrier treated substrate by treating a substrate with a liquid
applied, vapour permeable air and water barrier coating composition
comprising a cross-linked polysiloxane dispersion composition
comprising: (i) a crosslinked polysiloxane dispersion of: a
reaction product of (a) a siloxane polymer having at least two --OH
groups per molecule, or polymer mixture having at least two --OH
groups per molecule, having a viscosity of between 5,000 to 500,000
mPas at 25.degree. C., and (b) at least one self catalyzing
crosslinker reactive with (a), and additionally comprising (c) a
surfactant and (d) water; together with one or more of the
following ingredients: (ii) one or more fillers selected from the
group of colloidal silica, fumed silica, precipitated silica,
diatomaceous earths, ground quartz, kaolin, calcined kaolin,
wollastonite, hydroxyapatite, calcium carbonate, hydrated alumina,
magnesium hydroxide, carbon black, titanium dioxide, aluminium
oxide, vermiculite, zinc oxide, mica, talcum, iron oxide, barium
sulphate and slaked lime; (iii) one or more stabilizers; and (iv)
one or more rheology modifiers.
2. The method in accordance with claim 1 characterised in that the
cross-linked polysiloxane dispersion composition is applied on to a
substrate at a wet thickness of from 20 to 50 mil and dries
subsequent to application to a dry thickness of from 10 to 25
mil.
3. The method in accordance with claim 1 characterised in that the
cross-linked polysiloxane dispersion composition, once dried on a
substrate, meets the requirements of ASTM E2178-11, Standard Test
Method for Air Permeance of Building Materials, having an Air
Permeance (L/s per m.sup.2) of less than 0.006 at a differential
pressure of 75 Pa at thicknesses of both 10 and 15 mil.
4. The method in accordance with claim 1 characterised in that the
cross-linked polysiloxane dispersion composition, once dried on a
substrate meets Water Vapour Transmission Dry Cup Desiccant Method
in accordance with ASTM E96/E96M-10, Standard Test Method for Water
Vapour Transmission rate of Materials of greater than 10 US Perm,
and Water Vapour Transmission Wet Cup Water Method in accordance
with ASTM E96/E96M-10, Standard Test Method for Water Vapour
Transmission rate of Materials of greater than 20 US Perm, for
coatings of 15 mil thickness.
5. The method in accordance with claim 1 characterised in that the
cross-linked polysiloxane dispersion composition, once dried on a
substrate, passes the Self Sealability (Head of Water) Test
described in Section 8.9 of ASTM D1970-09.
6. The method in accordance with claim 2 wherein the substrate is
selected from construction sheathing substrate(s), masonry
substrate(s), metal substrate(s), galvanized metal substrate(s),
and wood framing substrate(s), and any combination thereof.
7. The method in accordance with claim 1 wherein the substrate is a
masonry substrate.
8. A wall assembly comprising a liquid applied, vapour permeable
air and water barrier coating composition comprising a cross-linked
polysiloxane dispersion composition comprising: (i) a crosslinked
polysiloxane dispersion of: a reaction product of (a) a siloxane
polymer having at least two --OH groups per molecule, or polymer
mixture having at least two --OH groups per molecule, having a
viscosity of between 5,000 to 500,000 mPas at 25.degree. C., and
(b) at least one self catalyzing crosslinker reactive with (a), and
additionally comprising (c) a surfactant and (d) water; together
with one or more of the following ingredients: (ii) one or more
fillers selected from the group of colloidal silica, fumed silica,
precipitated silica, diatomaceous earths, ground quartz, kaolin,
calcined kaolin, wollastonite, hydroxyapatite, calcium carbonate,
hydrated alumina, magnesium hydroxide, carbon black, titanium
dioxide, aluminium oxide, vermiculite, zinc oxide, mica, talcum,
iron oxide, barium sulphate and slaked lime; (iii) one or more
stabilizers; and (iv) one or more rheology modifiers.
9. The wall assembly in accordance with claim 8 characterised in
that the cross-linked polysiloxane dispersion composition is
applied on to a substrate at a wet thickness of from 20 to 50 mil
and dries subsequent to application to a dry thickness of from 10
to 25 mil.
10. The wall assembly in accordance with claim 8 characterised in
that the cross-linked polysiloxane dispersion composition, once
dried on a substrate, meets the requirements of ASTM E2178-11,
Standard Test Method for Air Permeance of Building Materials,
having an Air Permeance (L/s per m.sup.2) of less than 0.006 at a
differential pressure of 75 Pa at thicknesses of both 10 and 15
mil.
11. The wall assembly in accordance with claim 8 characterised in
that the cross-linked polysiloxane dispersion composition, once
dried on a substrate, meets Water Vapour Transmission Dry Cup
Desiccant Method in accordance with ASTM E96/E96M-10, Standard Test
Method for Water Vapour Transmission rate of Materials of greater
than 10 US Perm, and Water Vapour Transmission Wet Cup Water Method
in accordance with ASTM E96/E96M-10, Standard Test Method for Water
Vapour Transmission rate of Materials of greater than 20 US Perm,
for coatings of 15 mil thickness.
12. The wall assembly in accordance with claim 8 characterised in
that the cross-linked polysiloxane dispersion composition, once
dried on a substrate, passes the Self Sealability (Head of Water)
Test described in Section 8.9 of ASTM D1970-09.
13. The wall assembly in accordance with claim 8 comprising a
substrate selected from construction sheathing substrate(s),
masonry substrate(s), metal substrate(s), galvanized metal
substrate(s), and wood framing substrate(s) and any combination
thereof.
14. The wall assembly in accordance with claim 8 comprising a
masonry substrate.
15. A liquid applied, air and water barrier coating composition
comprising: (i) a crosslinked polysiloxane dispersion of: a
reaction product of (a) a siloxane polymer having at least two --OH
groups per molecule, or polymer mixture having at least two --OH
groups per molecule, having a viscosity of between 5,000 to 500,000
mPas at 25.degree. C., and (b) at least one self catalyzing
crosslinker reactive with (a), and additionally comprising (c) a
surfactant and (d) water; together with one or more of the
following ingredients: (ii) one or more fillers selected from the
group of colloidal silica, fumed silica, precipitated silica,
diatomaceous earths, ground quartz, kaolin, calcined kaolin,
wollastonite, hydroxyapatite, calcium carbonate, hydrated alumina,
magnesium hydroxide, carbon black, titanium dioxide, aluminium
oxide, vermiculite, zinc oxide, mica, talcum, iron oxide, barium
sulphate and slaked lime or a mixture thereof; (iii) one or more
stabilizers; and (iv) one or more rheology modifiers.
16. The liquid applied, air and water barrier coating composition
in accordance with claim 15 characterised in that the cross-linked
polysiloxane dispersion composition, once dried on a substrate,
meets the requirements of ASTM E2178-11, Standard Test Method for
Air Permeance of Building Materials, having an Air Permeance (L/s
per m.sup.2) of less than 0.006 at a differential pressure of 75 Pa
at thicknesses of 10 mil (0.254 mm) and 15 mil (0.381 mm).
17. The liquid applied, air and water barrier coating composition
in accordance with claim 15 characterised in that the cross-linked
polysiloxane dispersion composition once dried, has a Water Vapour
Transmission of greater than 7 US Perm (400.5 ng.s.sup.-1m.sup.-2
Pa.sup.-1), according to the Dry Cup Desiccant Method of ASTM
E96/E96M-10 for both the 10 mil (0.254 mm) and 15 mil (0.381 mm)
thicknesses; and, Standard Test Method for Water Vapour
Transmission rate of Materials and in accordance with Water Vapour
Transmission Wet Cup Water Method of ASTM E96/E96M-10, Standard
Test Method for Water Vapour Transmission rate of Materials of
greater than 30 US Perm (1716.41 ng.s.sup.-1m.sup.-2 Pa.sup.-1) for
coating of 10 mil (0.254 mm) thickness and greater than 24 US Perm
(1373.12 ng.s.sup.-1m.sup.-2 Pa.sup.-1) for coatings of 15 mil
(0.381 mm) thickness.
18. The liquid applied, air and water barrier coating composition
in accordance with claim 15 characterised in that the cross-linked
polysiloxane dispersion composition, once dried on a substrate,
passes the Self Sealability (Head of Water) Test described in
Section 8.9 of ASTM D1970-09.
19. The liquid applied, air and water barrier coating composition
in accordance with claim 15 characterised in that the cross-linked
polysiloxane dispersion composition comprises, excluding additives
(on the basis that the (product of (a)+(b))+(c)+(d) is 100% by
weight), 70 to 90% by weight of the reaction product of (a)+(b), 3
to 10% by weight of (c) and 7 to 20% by weight of component
(d).
20. The liquid applied, air and water barrier coating composition
in accordance with claim 15 characterised in that the cross-linked
polysiloxane dispersion composition is applied on to a substrate at
a wet thickness of from 20 to 50 mil and dries subsequent to
application to a dry thickness of from 10 to 25 mil.
Description
RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent
Application No. 61/751,428, filed on Jan. 11, 2013; U.S.
Provisional Patent Application No. 61/824,152, filed on May 16,
2013; and U.S. Provisional Patent Application No. 61/905,465, filed
on Nov. 18, 2013, the contents of each are hereby incorporated by
reference in their entirety.
TECHNICAL FIELD
[0002] This disclosure relates to the use of a cross-linked
polysiloxane dispersion composition as a vapour permeable air and
water barrier in the construction industry.
BACKGROUND
[0003] A wide variety of air and water bather systems are used in
both new building and remedial construction applications. These
barrier systems are designed to eliminate uncontrolled air and
water leakage through e.g. exterior walls and/or facades enabling
the control of e.g. temperature, humidity levels, moisture levels
and air quality throughout a building thereby minimising, for
example, the possibility of damp problems and/or the chance of
mould growth and poor air quality.
[0004] Air barriers are designed to minimise and potentially
exclude the passage of air through, e.g., walls. Water barriers are
intended to minimise or exclude the ingress of liquid water from
entering a building through a wall or facade or the like e.g. via
capillary action through cracks, holes or porous materials. The
application of such barrier systems to constructions, e.g. cavity
wall systems, results in energy cost savings and may significantly
reduce the ingress of airborne pollutants by substantially reducing
the amount of air leakage through the exterior walls or facades of
a building.
[0005] A single material can function as an air and water barrier.
Air and water barriers are typically found in two forms, sheet
materials and liquid coating compositions. Each type is usually
designed to be either (water) vapour permeable or impermeable.
Vapour Impermeable Air and water barrier coatings effectively block
the transfer of water vapour through the coating, whilst vapour
permeable Air and water barrier coatings control the amount of
(water) vapour diffusing through a wall due to variable vapour
pressures. Unless prevented or controlled, water vapour will
naturally move from a high concentration to a lower concentration
until it is in balance. Hence, if the vapour pressure is high
outside the wall and low inside the wall, vapour will be directed
inward (and vice versa).
[0006] The use of liquid-applied vapour permeable air and water
bathers for wall assemblies has only recently significantly
increased, not least because air leakage has become recognized as a
potential source of moisture accumulation in walls. This type of
air and water barrier is designed to allow moisture vapour to pass
through the membrane, promoting diffusion. Determining whether to
use a vapour permeable or vapour impermeable air and water barrier
(and indeed the degree of vapour permeability in a selected
barrier) is determined through local climate of the building and
the wall design itself i.e. the inter-relationship of the air/water
barrier and the insulation layer are located in relation to each
other in the wall.
[0007] Liquid-applied Vapour permeable, air and water barrier
coatings can be formed by applying a liquid coating composition
onto a suitable internal building construction surface.
Liquid-applied air and water barriers are rolled, sprayed or
trowelled onto substrates and become part of the internal
structural wall. Because of the way they are applied, there are no
fastener holes from the installation where water penetration may
occur, and there is no potential for mislapping or tearing, as with
many sheet materials.
[0008] Another important distinction of a liquid-applied air and
water barrier in wall assemblies is that they can minimize
application error and unintentional air infiltration caused by the
over-lapping of sheet applied materials. The liquid-applied
materials are applied and dry or cure as a monolithic membrane
around the building envelope.
[0009] A variety of both vapour permeable and impermeable air and
water barrier coatings are commercially available with the vast
majority being organic based coatings. Unfortunately however, these
organic based coatings have compatibility issues with silicone
based materials, such as caulks and weather sealants. The lack of
compatibility may lead to the inability to use such silicone
materials or the need for complex and potentially additional layers
of adhesives, primers and/or adhesion promoters prior to
application of silicone caulks and/or sealants etc. This renders
the construction process more expensive and complicated as it may
necessitate additional labour and more complicated application
processes in order to provide a "weather-tight" building.
[0010] Another disadvantage with organic coatings of the type
currently used for currently typically used is that they have poor
UV stability (unlike silicone based materials) and as such cannot
be exposed to UV radiation for extended periods of time during
construction without necessitating re-application of one or more
additional coating layer(s), which obviously adds to the cost of
the process. WO2012/064611 proposes a silicone based fluid applied
silicone air and water barrier system.
SUMMARY OF INVENTION
[0011] It has been surprisingly identified that a one-component
cross-linked polysiloxane dispersion composition may be used as a
liquid applied, vapour permeable air and water barrier coating
composition for application to internal wall assemblies.
[0012] There is provided herein the use of a cross-linked
polysiloxane dispersion composition comprising [0013] (i) a
crosslinked polysiloxane dispersion of a reaction product of (a) a
siloxane polymer having at least two --OH groups per molecule, or
polymer mixture having at least two --OH groups per molecule,
having a viscosity of between 5,000 to 500,000 mPas at 25.degree.
C., and (b) at least one self catalyzing crosslinker reactive with
(a), and additionally comprising (c) a surfactant and (d) water;
together with one or more of the following ingredients: [0014] (ii)
one or more fillers selected from the group of colloidal silica,
fumed silica, precipitated silica, diatomaceous earths, ground
quartz, kaolin, calcined kaolin, wollastonite, hydroxyapatite,
calcium carbonate, hydrated alumina, magnesium hydroxide, carbon
black, titanium dioxide, aluminium oxide, vermiculite, zinc oxide,
mica, talcum, iron oxide, barium sulphate and slaked lime; [0015]
(iii) one or more stabilizers; [0016] (iv) one or more rheology
modifiers as a liquid applied, vapour permeable air and water
barrier coating composition.
[0017] There is also provided herein a method for decreasing the
vapour permeability of a water and air barrier treated substrate by
treating said substrate with a liquid applied, vapour permeable air
and water barrier coating composition comprising a cross-linked
polysiloxane dispersion composition comprising [0018] (i) a
crosslinked polysiloxane dispersion of a reaction product of (a) a
siloxane polymer having at least two --OH groups per molecule, or
polymer mixture having at least two --OH groups per molecule,
having a viscosity of between 5,000 to 500,000 mPas at 25.degree.
C., and (b) at least one self catalyzing crosslinker reactive with
(a), and additionally comprising (c) a surfactant and (d) water;
together with one or more of the following ingredients: [0019] (ii)
one or more fillers selected from the group of colloidal silica,
fumed silica, precipitated silica, diatomaceous earths, ground
quartz, kaolin, calcined kaolin, wollastonite, hydroxyapatite,
calcium carbonate, hydrated alumina, magnesium hydroxide, carbon
black, titanium dioxide, aluminium oxide, vermiculite, zinc oxide,
mica, talcum, iron oxide, barium sulphate and slaked lime; [0020]
(iii) one or more stabilizers; and [0021] (iv) one or more rheology
modifiers
[0022] There is also provided herein a wall assembly comprising a
liquid applied, vapour permeable air and water barrier coating
composition comprising a cross-linked polysiloxane dispersion
composition comprising [0023] (i) a crosslinked polysiloxane
dispersion of a reaction product of (a) a siloxane polymer having
at least two --OH groups per molecule, or polymer mixture having at
least two --OH groups per molecule, having a viscosity of between
5,000 to 500,000 mPas at 25.degree. C., and (b) at least one self
catalyzing crosslinker reactive with (a), and additionally
comprising (c) a surfactant and (d) water; together with one or
more of the following ingredients: [0024] (ii) one or more fillers
selected from the group of colloidal silica, fumed silica,
precipitated silica, diatomaceous earths, ground quartz, kaolin,
calcined kaolin, wollastonite, hydroxyapatite, calcium carbonate,
hydrated alumina, magnesium hydroxide, carbon black, titanium
dioxide, aluminium oxide, vermiculite, zinc oxide, mica, talcum,
iron oxide, barium sulphate and slaked lime; [0025] (iii) one or
more stabilizers; and [0026] (iv) one or more rheology
modifiers.
DESCRIPTION
[0027] The liquid applied, vapour permeable air and water barrier
coating composition as hereinbefore described is applied at a wet
thickness of from 20 mil (0.508 mm) to 50 mil (1.27 mm), or from 20
to 60 mil (1.524 mm) and dries subsequent to application to a dry
thickness of from 10 mil (0.254 mm) to 25 mil (0.635 mm), or from
10 to 30 mil (0.762 mm). Depending on temperature, humidity and
wind conditions, the average drying time of the composition is from
about 4 to 12 hours and full adhesion and physical properties will
be present after only a few days.
[0028] The liquid applied, vapour permeable air and water barrier
coating composition as hereinbefore described, once dried on a
substrate, meets the requirements of ASHRAE 90.1-2010 for ASTM
E2178-11, Standard Test Method for Air Permeance of Building
Materials, having an Air Permeance (L/s per m.sup.2) of less than
0.006 at a differential pressure of 75 Pa at thicknesses of both 10
mil (0.254 mm) and 15 mil (0.381 mm)
[0029] The liquid applied, vapour permeable air and water barrier
coating composition, once dried, has a Water Vapour Transmission of
greater than 7 US Perm (400.49 ng.s.sup.-1m.sup.-2 Pa.sup.-1),
greater than 10 US Perm (572.135 ng.s.sup.-1m.sup.-2 pa.sup.-1), or
greater than 15 US Perm (858.2035 ng.s.sup.-1m.sup.-2 Pa.sup.-1),
according to the Dry Cup Desiccant Method of ASTM E96/E96M-10 for
both the 10 mil (0.254 mm) and 15 mil (0.381 mm) thicknesses,
Standard Test Method for Water Vapour Transmission rate of
Materials and in accordance with Water Vapour Transmission Wet Cup
Water Method of ASTM E96/E96M-10, Standard Test Method for Water
Vapour Transmission rate of Materials of greater than 20 US Perm
(1144.27 ng.s.sup.-1m.sup.-2 pa.sup.-1), greater than 24 US Perm
(1373.12 ng.s.sup.-1m.sup.-2 pa.sup.-1), greater than 25 US Perm
(1430.3375 ng.s.sup.-1m.sup.-2 Pa.sup.1), or greater than 30 US
Perm (1716.41 ng.s.sup.-1 m.sup.2 Pa.sup.-1) for coatings of 10 mil
(0.254 mm) thickness and for coatings of 15 mil (0.381 mm)
thicknesses.
[0030] Furthermore, the liquid applied, vapour permeable air and
water barrier coating composition as hereinbefore described, once
dried passes the Self Sealability (Head of Water) Test described in
Section 8.9 of ASTM D1970-09.
[0031] The wall assembly described herein can comprise the use of
the liquid applied, vapour permeable air and water barrier coating
composition as an adhesive to bond elastomer material(s) to
construction sheathing substrate(s), metal substrate(s) such as
painted or unpainted aluminium substrates, galvanized metal
substrate(s), wood framing substrate(s) and the like. Other
suitable substrates include, for the sake of example, concrete,
oriented strand board (OSB), exterior sheathing, preformed panels,
plywood and wood or steel stud walls.
[0032] All viscosity measurements of siloxane materials are made at
25.degree. C. using a recording Brookfield viscometer with Spindle
3 at 2 rpm according to ASTM D4287-00 (2010) unless otherwise
indicated.
[0033] The liquid applied, vapour permeable air and water barrier
coating composition comprises a crosslinked polysiloxane dispersion
containing a reverse phase emulsion of: [0034] (i) a reaction
product of (a) a siloxane polymer having at least two --OH groups
per molecule, or polymer mixture having at least two --OH groups
per molecule, having a viscosity of between 5,000 to 500,000 mPas
at 25.degree. C., and (b) at least one self catalyzing crosslinker
reactive with (a), additionally comprising (c) a surfactant and (d)
water; together with one or more of the following ingredients:
[0035] (ii) one or more fillers selected from the group of
colloidal silica, fumed silica, precipitated silica, diatomaceous
earths, ground quartz, kaolin, calcined kaolin, wollastonite,
hydroxyapatite, calcium carbonate, hydrated alumina, magnesium
hydroxide, carbon black, titanium dioxide, aluminium oxide,
vermiculite, zinc oxide, mica, talcum, iron oxide, barium sulphate
and slaked lime; [0036] (iii) one or more stabilizers; and [0037]
(iv) one or more rheology modifiers.
[0038] The reaction product (i) may additionally comprise one or
more additives such as in-situ resin reinforcers, stabilizers, e.g.
pH stabilizers, fillers and the like may also be added to the
mixture. The dispersion is produced by mixing the above components
at a sufficiently high shear to transform the mixture into a gel
phase and by then diluting the gel with water to the desired
silicone content.
[0039] The siloxane polymers or polymer mixtures (a) used as
starting materials for the reaction product (i) above have a
viscosity between 5,000 to 500,000 mPas. at 25.degree. C. using a
recording Brookfield viscometer with Spindle 3 at 2 rpm according
to ASTM D4287-00 (2010). The siloxane polymers are described by the
following molecular Formula (1)
X.sub.3-nR.sub.n--YO--(R.sup.1.sub.2SiO).sub.z--Y--R.sub.nX.sub.3-n
(1)
where n is 0, 1, 2 or 3, z is an integer from 500 to 5000
inclusive, X is a hydrogen atom, a hydroxyl group and any
condensable or any hydrolyzable group, Y is a Si atom or an
Si--(CH.sub.2).sub.m--SiR.sup.1.sub.2 group, R is individually
selected from the group consisting of aliphatic, alkyl, aminoalkyl,
polyaminoalkyl, epoxyalkyl, alkenyl or aromatic aryl groups and
R.sup.1 is individually selected from the group consisting of X,
aliphatic, alkyl, alkenyl and aromatic groups.
[0040] The siloxane polymer (a) can be a single siloxane
represented by Formula (1) or it can be mixtures of siloxanes
represented by the aforesaid formula or solvent/polymer mixtures.
The term "polymer mixture" is meant to include any of these types
of polymers or mixtures of polymers. As used herein, the term
"silicone content" means the total amount of silicone in the
dispersed phase of the dispersion, from whatever source, including,
but not limited to the silicone polymer, polymer mixtures, self
catalytic crosslinkers, in situ resin reinforcers and
stabilizers.
[0041] Each X group may be the same or different and can be a
hydrogen atom, hydroxyl group and any condensable or hydrolyzable
group. The term "hydrolyzable group" means any group attached to
the silicon which is hydrolyzed by water at room temperature. The
hydrolyzable group X includes hydrogen atom, halogen atoms, such as
F, Cl, Br or I; groups of the Formula --OT, where T is any
hydrocarbon or halogenated hydrocarbon group, such as methyl,
ethyl, isopropyl, octadecyl, allyl, hexenyl, cyclohexyl, phenyl,
benzyl, beta-phenylethyl; any hydrocarbon ether radical, such as
2-methoxyethyl, 2-ethoxyisopropyl, 2-butoxyisobutyl,
p-methoxyphenyl or --(CH.sub.2CH.sub.2O).sub.2CH.sub.3; or any
N,N-amino radical, such as dimethylamino, diethylamino,
ethylmethylamino, diphenylamino or dicyclohexylamino. X can also be
any amino radical, such as NH.sub.2, dimethylamino, diethylamino,
methylphenylamino or dicyclohexylamino; any ketoxime radical of the
formula --ON.dbd.CM.sub.2 or --ON.dbd.CM' in which M is any
monovalent hydrocarbon or halogenated hydrocarbon radical, such as
those shown for T above and M' is any divalent hydrocarbon radical,
both valences of which are attached to the carbon, such as
hexylene, pentylene or octylene; ureido groups of the formula
--N(M)CONM''.sub.2 in which M is defined above and M'' is hydrogen
atom or any of the above M radicals; carboxyl groups of the formula
--OOCMM'' in which M and M'' are defined above or carboxylic amide
radicals of the formula --NMC.dbd.O(M'') in which M and M'' are
defined above. X can also be the sulphate group or sulphate ester
groups of the formula --OSO.sub.2(OM), where M is as defined above;
the cyano group; the isocyanate group; and the phosphate group or
phosphate ester groups of the formula --OPO(OM).sub.2 in which M is
defined above.
[0042] The most preferred X groups of the invention are hydroxyl
groups or alkoxy groups. Illustrative alkoxy groups are methoxy,
ethoxy, propoxy, butoxy, isobutoxy, pentoxy, hexoxy and
2-ethylhexoxy; dialkoxy radicals, such as methoxymethoxy or
ethoxymethoxy and alkoxyaryloxy, such as ethoxyphenoxy. The most
preferred alkoxy groups are methoxy or ethoxy.
[0043] R is individually selected from the group consisting of
aliphatic, alkyl, aminoalkyl, polyaminoalkyl, epoxyalkyl, alkenyl
organic and aromatic aryl groups. Most preferred are the methyl,
ethyl, octyl, vinyl, allyl and phenyl groups.
[0044] R.sup.1 is individually selected from the group consisting
of X, aliphatic, alkyl, alkenyl and aromatic aryl groups. Most
preferred are methyl, ethyl, octyl, trifluoropropyl, vinyl and
phenyl groups.
[0045] When the siloxane polymer of formula (1) has an average of
more than two condensable or hydrolyzable groups per molecule which
are self catalytic, it is not necessary to have the self catalytic
crosslinker present separately to form a crosslinked polymer. The
condensable or hydrolyzable groups on the different siloxane
molecules can react with each other to form the required
crosslinks.
[0046] The siloxane polymer (a) can be a mixture of different kinds
of molecules, for example, long chain linear molecules and short
chain linear or branched molecules. These molecules may react with
each other to form a crosslinked network. Such siloxanes, which can
take the place of more conventional crosslinkers, are illustrated
by low molecular weight organosilicon hydrides, such as
polymethylhydrogensiloxane, low molecular weight copolymers
containing methylhydrogensiloxy and dimethylsiloxy groups,
--(OSi(OEt).sub.2)--, (ethylpolysilicate),
(OSiMeC.sub.2H.sub.4Si(OMe).sub.3).sub.4 and
(OSi--MeON.dbd.CR'.sub.2).sub.4, where Me is methyl and Et is
ethyl.
[0047] Advantageously, the siloxane polymer (a) also comprises
mixtures of siloxane polymers of formula (1), exemplified by, but
not limited to, mixtures of .alpha.,.omega.-hydroxysiloxy
terminated siloxanes and of .alpha.,.omega.-bis(triorganosiloxy)
terminated siloxanes, mixtures of .alpha.,.omega.-hydroxylsiloxy
terminated siloxanes and of .alpha.-hydroxy,
.omega.-triorganosiloxy terminated siloxanes, mixtures of
.alpha.,.omega.-dialkoxysiloxy terminated siloxanes and of
.alpha.,.omega.-bis(triorganosiloxy) terminated siloxanes, mixtures
of .alpha.,.omega.-dialkoxysiloxy terminated siloxanes and of
.alpha.,.omega.-hydroxysiloxy terminated siloxanes, mixtures of
.alpha.,.omega.-hydroxysiloxy terminated siloxanes and of
.alpha.,.omega.-bis(triorganosiloxy) terminated
poly(diorgano)(hydrogenorgano)siloxane copolymers. The siloxane
polymer of the invention can also comprise mixtures of siloxane
polymers of formula (1) as described above with liquid, branched
methylpolysiloxane polymers ("MDT fluids") comprising a combination
of recurring units of the formulae:
(CH.sub.3).sub.3SiO.sub.1/2("M")
(CH.sub.3).sub.2SiO("D")
CH.sub.3SiO.sub.3/2("T")
and containing from 0.1 to 8% hydroxyl groups. The fluids may be
prepared by co-hydrolysis of the corresponding chloro- or
alkoxy-silanes, as described, for example, in U.S. Pat. No.
3,382,205. The proportion of MDT fluids added should not exceed 50
parts, preferably of 1 to 20 parts by weight, per 100 parts by
weight of the polymer of Formula (1), to achieve improved physical
properties and adhesion of the resultant polymers. The siloxane
polymer of the present invention can also comprise mixtures of
siloxane polymers of Formula (1) with liquid or solid, branched
methylsiloxane polymeric resins comprising a combination of
recurring units of the formulae:
(CH.sub.3).sub.3SiO.sub.1/2("M")
(CH.sub.3).sub.2SiO("D")
CH.sub.3SiO.sub.3/2("T")
SiO.sub.4/2("Q")
and containing from 0.1 to 8% hydroxyl groups, the fluids may be
prepared by co-hydrolysis of the corresponding chloro- or
alkoxy-silanes, as described, for example in U.S. Pat. No.
2,676,182. The MDTQ fluid/resin may be added in a proportion not
exceeding 50 parts, preferably of 1 to 10 parts by weight, per 100
parts by weight of the polymer of Formula (1) to improve physical
properties and adhesion of the resultant polymers. MDTQ
fluids/resins can also be mixed with MDT fluids and the polymers of
Formula (1).
[0048] Finally, the siloxane polymer (a) can comprise mixtures of
siloxane polymers of Formula (1) with compatible organic solvents,
to form organic polymer/solvent mixtures. These organic solvents
are exemplified by organophosphate esters, alkanes, such as hexane
or heptane; higher paraffins; and aromatic solvents, such as
toluene or benzene. The polymer solvent mixtures can also be added
with MDT fluids and/or MDTQ fluids to the polymer of Formula (1).
Any of the above mixtures of polymers or polymer/solvents can be
prepared by mixing the ingredients prior to emulsification or by
emulsifying them individually and then mixing the prepared
emulsions.
[0049] The at least one self catalytic crosslinker (b) reactive
with (a) to form reaction product (i) is present in the amount of 1
to 5 parts by weight per 100 parts of siloxane polymer. The term
"self catalytic crosslinker" means a molecule that has at least one
group serving as the catalytic species. While in certain
circumstances only one self catalytic crosslinker may be needed to
produce an elastomer having the desired physical properties, those
skilled in the art will recognize that two or more self catalytic
crosslinkers may be added to the reaction mixture to achieve
excellent results. In addition, the self catalytic crosslinker or
crosslinkers may be added with a conventional catalyst. However,
adding the self catalytic crosslinker with a conventional catalyst
is not required for the practice of this invention and the
compositions contemplated by this invention may in fact be free of
said conventional catalysts.
[0050] Typical self catalytic crosslinkers include tri or tetra
functional compounds, such as R--Si-(Q).sub.3 or Si-(Q).sub.4,
where Q is carboxylic, OC(O)R.sup.4, e.g., acetoxy and R.sup.4 is
an alkyl group of 1 to 8 carbon atoms inclusive, preferably methyl,
ethyl or vinyl. Other preferred Q groups are the hydroxylamines,
ON(R.sup.4).sub.2, where each R.sup.4 is the same or different
alkyl group of 1 to 8 carbon atoms inclusive, e.g.,
ON(CH.sub.2CH.sub.3).sub.2. Q may also be an oxime group, such as
O--N.dbd.C(R.sup.4).sub.2, where each R.sup.4 is the same or
different alkyl group of 1 to 8 carbon atoms inclusive, e.g.,
O--N.dbd.C(CH.sub.3)(CH.sub.2CH.sub.3). Further, Q may be an amine
group, such as N(R.sup.5).sub.2, where R.sup.5 is the same or
different alkyl group of 1 to 8 carbon atoms inclusive or cyclic
alkyl group, e.g., N(CH.sub.3).sub.2 or NH(cyclohexyl). Finally, Q
may be an acetamido group, NRC(O)R.sup.4, where R.sup.4 is an alkyl
group of 1 to 8 carbon atoms inclusive, e.g.
N(CH.sub.3)C(O)CH.sub.3.
[0051] In addition, partial hydrolysis products of the
aforementioned compounds may also function as self catalytic
crosslinkers. This would include dimers, trimers, tetramers and the
like, for example, compounds of the formula:
##STR00001##
where Q and R.sup.4 are defined in the preceding paragraph.
[0052] Also useful as self catalytic crosslinkers are those
polymeric or copolymeric species containing 3 or more (Q) sites
located at either pendant or terminal positions or both on the
backbone of a polydiorganosiloxane molecule. Examples of the
pendent group include compositions of the following formula:
##STR00002##
where R.sup.4 is the same or different alkyl group of from 1 to 8
carbon atoms inclusive and a is 0 or a positive integer and b is an
integer greater than 2. In general, polymeric compositions having
either pendent or terminal Q groups may be used in the practice of
the present invention, in particular, compounds of the formula:
Q.sub.3-nR.sup.6.sub.nSiO(R.sup.6.sub.2SiO).sub.zSiR.sup.6.sub.nQ.sub.3--
n
where n is 0, 1, 2 or 3, z is a positive integer, R.sup.6 is Q or
independently the same or different alkyl chain of 1 to 8 carbon
atoms inclusive as long as there are at least three Q groups on the
molecule. Q is as described above.
[0053] Effective self catalytic crosslinkers are those compounds
which form tack free elastomers when mixed with functional silicone
polymers in the absence of additional catalysts such as tin
carboxylates or amines. In the self catalytic crosslinkers, the
acetoxy, oxime, hydroxylamine (aminoxy), acetamide and amide groups
catalyze the formation of Si--O--Si bonds in the reactions
contemplated by this invention.
[0054] One skilled in the art would recognize that the starting
polymer itself could be pre-endblocked with self catalytic
crosslinking moieties. Optionally, further self-catalytic
crosslinkers can be added to such compositions.
[0055] The surfactant (c) may be selected from nonionic
surfactants, cationic surfactants, anionic surfactants, amphoteric
surfactants or mixtures thereof. The surfactant (c) is present in
our composition in an amount of 0.5 to 10 parts by weight of
siloxane polymer (a) and is preferably present in the amount of 2
to 10 parts.
[0056] Most preferred are nonionic surfactants known in the art as
being useful in emulsification of polysiloxanes. Useful nonionic
surfactants are polyoxyalkylene alkyl ethers, polyoxyalkylene
sorbitan esters, polyoxyalkylene esters, polyoxyalkylene
alkylphenyl ethers, ethoxylated amides and others. The surfactants
useful in the instant invention may be further exemplified by
TERGITOL.RTM. TMN-6, TERGITOL.RTM. 15S40, TERGITOL.RTM. 15S9,
TERGITOL.RTM. 15S12, TERGITOL.RTM. 15S15 and TERGITOL.RTM. 15S20,
and TRITON.RTM. X405 produced by The Dow Chemical Company of
Midland, Mich.; BRIJ.RTM. 30 and BRIJ.RTM. 35; MAKON.RTM. 10
produced by STEPAN COMPANY, (Chicago, Ill.); and ETHOMID.RTM. O/17
produced by Akzo Nobel Surfactants (Chicago, Ill.).
[0057] Cationic and anionic surfactants known in the art as being
useful in emulsification of polysiloxanes are also useful as the
surfactant in the instant invention. Suitable cationic surfactants
are aliphatic fatty amines and their derivatives, such as
dodecylamine acetate, octadecylamine acetate and acetates of the
amines of tallow fatty acids; homologues of aromatic amines having
fatty chains, such as dodecylanalin; fatty amides derived from
aliphatic diamines, such as undecylimidazoline; fatty amides
derived from disubstituted amines, such as oleylaminodiethylamine;
derivatives of ethylene diamine; quaternary ammonium compounds,
such as tallow trimethyl ammonium chloride, dioctadecyldimethyl
ammonium chloride, didodecyldimethyl ammonium chloride and
dihexadecyldimethyl ammonium chloride; amide derivatives of amino
alcohols, such as beta-hydroxyethylstearyl amide; amine salts of
long chain fatty acids; quaternary ammonium bases derived from
fatty amides of di-substituted diamines, such as
oleylbenzylaminoethylene diethylamine hydrochloride; quaternary
ammonium bases of the benzimidazolines, such as methylheptadecyl
benzimidazole hydrobromide; basic compounds of pyridinium and its
derivatives, such as cetylpyridinium chloride; sulfonium compounds,
such as octadecylsulfonium methyl sulphate; quaternary ammonium
compounds of betaine, such as betaine compounds of diethylamino
acetic acid and octadecylchloromethyl ether; urethanes of ethylene
diamine, such as the condensation products of stearic acid and
diethylene triamine; polyethylene diamines and
polypropanolpolyethanol amines.
[0058] Cationic surfactants commercially available and useful in
the instant invention include ARQUAD.RTM. T27W, ARQUAD.RTM. 16-29,
ARQUAD.RTM. C-33, ARQUAD.RTM. T50, ETHOQUAD.RTM. T/13 ACETATE, all
manufactured by Akzo Nobel Surfactants (Chicago, Ill.).
[0059] Suitable anionic surfactants are carboxylic, phosphoric and
sulfonic acids and their salt derivatives. The anionic surfactants
useful in the instant invention are alkyl carboxylates; acyl
lactylates; alkyl ether carboxylates; n-acyl sarcosinate; n-acyl
glutamates; fatty acid-polypeptide condensates; alkali metal
sulforicinates; sulfonated glycerol esters of fatty acids, such as
sulfonated monoglycerides of coconut oil acids; salts of sulfonated
monovalent alcohol esters, such as sodium oleylisethionate; amides
of amino sulfonic acids, such as the sodium salt of oleyl methyl
tauride; sulfonated products of fatty acids nitriles, such as
palmitonitrile sulfonate; sulfonated aromatic hydrocarbons, such as
sodium alpha-naphthalene monosulfonate; condensation products of
naphthalene sulfonic acids with formaldehyde; sodium
octahydroanthracene sulfonate; alkali metal alkyl sulphates, ether
sulphates having alkyl groups of 8 or more carbon atoms and
alkylarylsulfonates having 1 or more alkyl groups of 8 or more
carbon atoms.
[0060] Anionic surfactants commercially available and useful in the
instant invention include POLYSTEP.RTM. A4, A7, A11, A15, A15-30K,
A16, A16-22, A18, A13, A17, B1, B3, B5, B11, B12, B19, B20, B22,
B23, B24, B25, B27, B29, C-OP3S; ALPHA-STEP.RTM. ML40, MC48;
STEPANOL.TM. MG; all produced by STEPAN CO., Chicago, Ill.;
HOSTAPUR.RTM. SAS produced by HOECHST CELANESE; HAMPOSYL.RTM. C30
and L30 produced by W.R.GRACE & CO., Lexington, Mass.
[0061] Suitable amphoteric surfactants are glycinates, betaines,
sultaines and alkyl aminopropionates. These include
cocoamphglycinate, cocoamphocarboxy-glycinates,
cocoamidopropylbetaine, lauryl betaine,
cocoamidopropylhydroxysultaine, laurylsulataine and
cocoamphodipropionate.
[0062] Amphoteric surfactants commercially available and useful in
the instant invention are REWOTERIC.RTM. AM TEG, AM DLM-35, AM B14
LS, AM CAS and AM LP produced by SHEREX CHEMICAL CO., Dublin,
Ohio.
[0063] Specifically, anionic surfactants include monovalent alkyl
carboxylates; polyvalent alkyl carboxylates; acyl lactylates; alkyl
ether carboxylates; n-acyl sarcosinate; n-acyl glutamates; and
fatty acid polypeptide condensates. Other anionic surfactants are
ester linked sulfonates, such as alkyl sulfo esters; taurates;
sulfosuccinates, such as monoester, diester (both symmetrical and
unsymmetrical), ethoxylated monoalkyl sulfosuccinates, alkyl amide
1/2 ester sulfosuccinate; sulfosuccinamates; sulfonated ethers, (Na
cocoglycerol ether sulfonate); linear alkylbenzenesulfonates;
benzene, toluene, xylene, cumene sulfonate; ligninsulfonates, such
as sulfonated polymers having number average molecular weights of
1,000-20,000; petroleum sulfonates, such as petroleum fractions of
differing molecular weights reacted with oleum or H.sub.2SO.sub.4
to sulfonate; paraffin sulfonates, such as sulfoxidation of
n-paraffins via UV/SO.sub.3 secondary alkane sulfonates
C.sub.14-C.sub.18 (e.g. HOECHST.TM. SAS); [alpha]-olefin
sulfonates; alkylnapthalene-sulfonates; diphenyl oxide sulphonates
and linear alkylpolyethersulfonates.
[0064] Specific non-ionic surfactants include ethoxylated alcohols,
ethoxylated esters, polysorbate esters, ethoxylated amides;
polyoxypropylene compounds, such as propoxylated alcohols,
ethoxylated/propoxylated block polymers and propoxylated esters;
alkanolamides; amine oxides; fatty acid esters of polyhydric
alcohols, such as ethylene glycol esters, diethylene glycol esters,
propylene glycol esters, glyceryl esters, polyglyceryl fatty acid
esters, sorbitan esters, sucrose esters and glucose esters.
[0065] Specific cationic surfactants include monoalkyl quaternary
ammonium salts, which are hydroxylated or ethoxylated,
propoxylated; dialkyl quaternary ammonium compounds; amidoamines;
and aminimides. Specific amphoteric surfactants include
N-substituted alkyl amides (i.e. fatty acid plus
aminoethanolamines, e.g., cocoamphoglycinate or
cocoamphocarboxyglycinate); N-alkyl betaines, including alkyl
amidobetaines; sulfobetaines, such as laurylsultaine,
cocoamidopropylhydroxysultaine; N-alkyl-b-aminopropionates, such as
lauraminopropionic acids.
[0066] Specific silicone surfactants which improve high temperature
stability include branched or linear polyoxyalkylenes. Specific
fluorosurfactants include those selected from anionics (such as
carboxylates and sulfonics), non-ionics and amphoterics.
[0067] The selection of the surfactant in the present invention
also influences the clarity of the elastomeric film resulting from
the evaporation of water from the dispersion. To obtain clear
elastomers from silicone lattices, the refractive index must be
matched in the final film between the crosslinked siloxane phase
and the surfactant/residual water phase. The term "crosslinked
siloxane phase" refers to the plurality of crosslinked siloxane
particles remaining after water has evaporated to form an
elastomeric film The term "surfactant/residual water phase" refers
to amount of residual surfactant and water remaining in the
elastomeric film after the evaporation of substantially all the
water from the dispersion.
[0068] In addition to adding the surfactant to the siloxane
polymer, the mixture also includes a predetermined amount of water.
The water is present in the mixture in an amount of 0.5 to 30 parts
by weight of siloxane polymer and is preferably present in the
amount of 2 to 10 parts. Water may also be added after mixing, in
any amount, to dilute the gel phase.
[0069] The reaction product (i) may additionally comprise one or
more additives such as in-situ resin reinforcers, stabilizers,
e.g., pH stabilizers, fillers and the like may also be added to the
mixture. The reaction product (i) is produced by mixing the above
components at a sufficiently high shear to transform the mixture
into a gel phase and by then diluting the gel with water to the
desired silicone content.
[0070] The reaction product of (a) a siloxane polymer having at
least two --OH groups per molecule, or polymer mixture having at
least two --OH groups per molecule, having a viscosity of between
5,000 to 500,000 mPas at 25.degree. C., and (b) at least one self
catalyzing crosslinker reactive with (a), additionally comprising
(c) a surfactant and (d) water; typically comprises, excluding
additives (i.e. on the basis that the (product of (a)+(b))+(c)+(d)
is 100% by weight), 70 to 90% by weight of the reaction product of
(a)+(b), 3 to 10% by weight of (c) and 7 to 20% by weight of
component (d). Alternatively, excluding additives (i.e. on the
basis that the (product of (a)+(b)+(c)+(d) is 100% by weight), 80
to 90% by weight of the reaction product of (a)+(b), 3 to 8% by
weight of (c) and 7 to 15% by weight of component (d).
[0071] In addition, in situ resin reinforcers, such as
methyltrimethoxy silane, vinyltrimethoxy silane, tetraethyl
orthosilicate (TEOS), normal propylorthosilicate (NPOS) may be
added with the self catalyzing crosslinker. It is believed that
adding in situ resin reinforcers to the polydiorganosiloxane/self
catalytic crosslinker mixture forms an in situ resin having a
highly branched and crosslinked structure, which results in
improved physical properties of the elastomer, particularly the
tensile, elongation and hardness properties. It also results in
improved clarity of the resulting elastomer.
[0072] Stabilizers may also be added to the composition. These may
comprise any suitable stabilizer, for example a pH stabilizer or
any aminosilane containing polymeric or neat aminosilane will
function as a stabilizer. Neat aminosilanes include compounds of
the formula
(R.sup.4O).sub.3-nR.sup.4.sub.nnsiQ.sup.1NR.sup.4.sub.yH.sub.2-y
where n and y are independently 0, 1 or 2; R.sup.4 is the same or
different alkyl chain of 1 to 8 carbon atoms inclusive, Q.sup.1 is
(CH.sub.2).sub.z or {(CH.sub.2).sub.zN(R.sup.4)}.sub.w, where z is
an integer from 1 to 10 and w is from 0 to 3 inclusive.
[0073] Polymeric amino silanes may also be used in the practice of
the present invention, such as reaction products of silanol
functional siloxane fluids and aminosilanes or silanol functional
siloxane fluids and alkoxysilanes and aminosilanes. For example,
one useful polymeric amino siloxane particularly useful has the
formula:
##STR00003##
where z is from 3 to 40.
[0074] To prepare the compositions of the instant invention,
siloxane polymer (a) and the self catalyzing crosslinker (b) are
mixed. Water (d) and surfactant (c) are then added to the siloxane
polymer (a) and the self catalyzing crosslinker (b) is mixed in
until a high solids gel phase is formed. Any type of mixing
equipment may be used including low shear mixing equipment, such as
Turrello(.TM.), Neulinger(.TM.) or Ross(.TM.) mixers. The gel will
also exhibit excellent shelf stability and may be stored for long
periods of time or even transported if required. The other
ingredients of the composition may be introduced during the
preparation of the pre-cured dispersion or alternatively may be
added into the composition in any suitable order prior to use and
after mixing, the resulting composition may be diluted with water
to the desired silicone content. Both the dispersion alone and the
composition may be stored for long periods of time and will exhibit
excellent freeze/thaw stability.
[0075] The cross-linked polysiloxane dispersion composition may
then be mixed with the other ingredients prior to use or dispensed
and will form an elastomeric film upon the evaporation of water.
The method of treating a substrate may include applying the
cross-linked polysiloxane dispersion to the substrate. As such, the
method of treating a substrate may further comprise evaporating
water from the cross-linked polysiloxane dispersion composition
after the cross-linked polysiloxane dispersion composition is
applied to the substrate to form a silicone latex elastomer on the
substrate. The step of evaporation of water may be performed under
ambient, or atmospheric conditions at the location of the substrate
when the cross-linked polysiloxane dispersion composition is
applied. Alternatively, the step of evaporation of water may be
performed under artificially heated conditions, produced by one or
more heaters.
[0076] Once prepared, the aforementioned reaction product (i) may
be mixed with the other ingredients of the composition in any
suitable order. It will be appreciated that all compositions
determined by wt % add up to a total of 100 wt %. The cross-linked
polysiloxane dispersion composition will typically comprise from 30
to 80 wt %, alternatively 30 to 60 wt %, alternatively 35 to 50 wt
% of reaction product (i) as hereinbefore described.
[0077] The cross-linked polysiloxane dispersion composition also
comprises one or more fillers. Suitable fillers include, for the
sake of example, colloidal silica, silica powders made by
combustion (fumed silica) and precipitation (precipitated silica),
semi-reinforcing agents, such as diatomaceous earths or ground
quartz. Nonsiliceous fillers may also be added, such as, calcium
carbonate, hydrated alumina, magnesium hydroxide, carbon black,
titanium dioxide, aluminium oxide, vermiculite, zinc oxide, mica,
talcum, iron oxide, barium sulphate, slaked lime, kaolin, calcined
kaolin, wollastonite, and hydroxyapatite.
[0078] Other fillers which might be used alone or in addition to
the above, include aluminite, calcium sulphate (anhydrite), gypsum,
calcium sulphate, magnesium carbonate, clays such as aluminium
trihydroxide, graphite, copper carbonate, e.g., malachite, nickel
carbonate, e.g., zarachite, barium carbonate, e.g., witherite
and/or strontium carbonate, e.g., strontianite; aluminium oxide,
silicates from the group consisting of olivine group; garnet group;
aluminosilicates; ring silicates; chain silicates; and sheet
silicates. The olivine group comprises silicate minerals, such as,
but not limited to, forsterite and Mg.sub.2SiO.sub.4. The garnet
group comprises ground silicate minerals, such as, but not limited
to, pyrope; Mg.sub.3Al.sub.2Si.sub.3O.sub.12; grossular; and
Ca.sub.2Al.sub.2Si.sub.3O.sub.12. Aluninosilicates comprise ground
silicate minerals, such as, but not limited to, sillimanite;
Al.sub.2SiO.sub.5; mullite; 3Al.sub.2O.sub.3.2SiO.sub.2; kyanite;
and Al.sub.2SiO.sub.5. The ring silicates group comprises silicate
minerals, such as but not limited to, cordierite and
Al.sub.3(Mg,Fe).sub.2[Si.sub.4AlO.sub.18]. If necessary, liquid
alkoxysilanes which are soluble in the siloxane polymer (a) may
also be added with the filler to compatibilise the filler with the
siloxane polymers.
[0079] The selection and addition of particular fillers to our
compositions, such as certain types of silicas, may improve the
physical properties of the resulting elastomer, particularly
tensile properties, elongation properties, hardness and heat
stability.
[0080] Typically the filler(s), when present are present in an
amount of from 10 to 200 weight parts of filler per 100 wt parts of
siloxane polymer (a), alternatively from 15 to 100 weight parts of
filler per 100 wt parts of siloxane polymer (a). Hydrophobing
agents may be provided to treat the aforementioned filler(s) to
render them hydrophobic and therefore more easily mixed with
reaction product (i) the hydrophobing agents may be for example
silanes, e.g., alkoxy silanes, silazanes and or short chain (2-20)
organopolysiloxanes or alternatively stearates or the like.
[0081] Elastomers containing ammonium stabilized silicas are heat
stable, while sodium stabilized silicas are not. Acidic silicas,
(those containing H.sup.+as a stabilizer) also yield heat stable
elastomers. In general, colloidal or dispersed silica which is not
stabilized by Group IA or IIA elements of the periodic chart, will
also yield heat stable elastomers. Volatile organic amines and
volatile inorganic bases are useful as stabilizers for silicas that
would yield heat stable elastomers, e.g.,
(R.sup.7).sub.3-xN(H).sub.x, where x=0, 1, 2 or 3, R.sup.7 is an
alkyl or aryl group, such as (CH.sub.3).sub.2NH or R.sup.7 is an
alcohol group, such as N(CH.sub.2CH.sub.2OH).sub.3 or
NH(CH.sub.2CH.sub.2OH).sub.2. The volatile organic amines include
cyclohexylamine, triethylamine, dimethylaminomethylpropanol,
diethylaminoethanol, aminomethyl propanol, aminobutanol,
monoethanolamine, monoisopropanolamine, dimethylethanolamine,
diethanolamine, aminoethylpropanediol, aminomethylpropanesiol,
diisopropanolamine, morpholine, tris(hydroxymethyl)aminomethane,
triisoproanolamine, triethanolamine, aniline and urea. In addition
to the volatile organic amines, volatile inorganic bases, such as
ammonia and ammonium carbonate, also yield heat stable
elastomers.
[0082] The composition may also contain one or more rheology
modifiers, such as, natural and modified natural materials, such
as, for example starch, modified starch, cellulose, modified
cellulose, proteins, and modified proteins. Alternatively, the
rheology modifiers may be synthetic including, for example,
(optionally hydrophobically treated) alkali swellable emulsions of
homo-polymers of (meth)acrylic acids and copolymers thereof with
methacrylate esters, hydrophobically modified ethoxylated urethane
resin, dimeric and trimeric fatty acids and/or imidazolines.
Furthermore, the rheology modifiers, when utilized, are present in
an amount of from 0.25 wt % to 5 wt % of the composition.
[0083] The composition may also comprise one or more pigments, such
as carbon black or titanium dioxide, and may also be added as
fillers. Since these fillers are only intended to affect the color
of the cured silicone latex elastomer, they are typically added at
0.1 to 20 weight parts, preferably from 0.5 to 10 weight parts, per
100 weight parts of siloxane polymer. Titanium dioxide has been
found to be particularly useful as an ultraviolet light screening
agent.
[0084] The composition may also comprise additional additives, such
as preservatives, buffers, fire retardants, coalescents,
disinfectants, corrosion inhibitors, antioxidants, antifoams and
biocides (optionally encapsulated), antifreeze materials, such as
polypropylene glycol and/or buffers.
[0085] Those skilled in the art will recognize that these
crosslinked, oil in water dispersions may be prepared in other
ways. For instance, the siloxane polymer and self catalytic
crosslinker mixture may be added to a surfactant and water solution
and then emulsified using colloid mills, homogenizers, sonolaters
or other high shear devices as described in U.S. Pat. Nos.
5,037,878 and 5,034,455.
[0086] The dispersion may be formed by either a batch process, as
described above, or a continuous process. If a continuous process
is used, then a low shear dynamic mixer or static mixer is
preferred.
[0087] The liquid coating may be spray-applied, brushed, rolled,
trowelled or otherwise coated onto a substrate although spraying
techniques are preferred. Once applied as a coating on the
substrate the composition will form an elastomeric film upon the
evaporation of water although it is to be noted that no cure
reaction takes place upon application to a substrate the coating
merely dries on the substrate surface, typically through water
evaporation.
[0088] Also given that the siloxane is pre-cured it was believed
that such compositions would be unable to successfully pass tests
such as the Self Sealability (Head of Water) Test described in
Section 8.9 of ASTM D1970-09 because it was not expected that the
film would be able to self-heal in order to maintain its integrity
and prevent water ingress etc. In both cases the composition as
hereinbefore described has unexpectedly proven to meet the
necessary requirements for these two matters. Furthermore, the
coating as described herein has the added advantage over many
currently available air/water barrier coatings in that it is
compatible with other silicone based products such as adhesives,
caulks and sealants.
[0089] Hence, the present composition may be used as a vapour
permeable air and water barrier coating in any building requiring
same, for example, cavity wall systems in climatic regions where
the provision of air and water barriers which are permeable to
(water) vapour are beneficial and when the structure of the cavity
wall is designed appropriately. As the skilled man appreciates,
cavity wall systems vary in structure to accommodate the local
climate, i.e., the relative positions of the insulation and
air/water barrier in the cavity wall system as the coating is
provided to enable the diffusion of water vapour through the
coating and is intended to be applied on a substrate with a view to
prevent the risk of moisture getting trapped in the wall cavity.
The composition herein is particularly suited for environments in
which high levels of (water) vapour permeability are advantageous
because of the surrounding climate. As will be seen below the
composition herein has a better Water Vapour Transmission in
accordance with ASTM E96/E96M-10 Dry Cup Desiccant Method, of
greater than 7 US Perm (400.49 ng.s.sup.-1m.sup.-2 pa.sup.-1) and a
Wet Cup Method of greater than 24 US perms for coatings of 15 mil
(0.381 mm) It is particularly to be noted that these dry cup
results for coatings of 15 mil (0.381 mm) thickness are
surprisingly different from the product described in
WO2012/064611.
[0090] The composition herein may be used as a vapour permeable
air/water barrier on any suitable substrate, such as for example
masonry substrates, such as concrete block, fluted block, brick,
stucco, synthetic stucco, poured concrete, precast concrete,
insulation finish systems (EIFS), shotcrete, gypsum as well as
gypsum board, wood, plywood and any other interior surfaces
requiring said barrier coating. The substrate may be located on
either the interior or exterior of load bearing supports of a wall
assembly. Indeed the substrate may be the aforementioned load
bearing support, e.g., a concrete masonry unit (CMU). Before the
cross-linked polysiloxane dispersion composition described above is
dried, the wall assembly comprises cross-linked polysiloxane
dispersion composition disposed on the substrate as described
above. However, after the cross-linked polysiloxane dispersion
composition is dried, the wall assembly comprises a vapour
permeable air and water barrier coating formed from drying or
evaporating the cross-linked polysiloxane dispersion composition
described above.
[0091] It is known that silicones have excellent overall
durability, including ultraviolet radiation exposure on buildings.
An air barrier needs to withstand a certain amount of ultraviolet
radiation during the time period after installation and before the
exterior building facade is installed. Some air barriers have a
limited exposure time before the manufacturer recommends covering
the air barrier with the building facade. As the current invention
is a silicone-based material the ultraviolet durability allows the
air barrier to be exposed indefinitely to the atmosphere or for at
least a long period of time which could enable greater flexibility
during construction or in the event of delays on the jobsite.
[0092] Many vapour permeable air and water barrier coatings are
organic solvent based and therefore have problems meeting today's
increasingly stringent environmental volatile organic compounds
requirements. The fact that the composition as hereinbefore
described is a water based material results in the present
composition avoiding such problems. Coating materials must meet the
ever increasingly stringent environmental requirements in order to
be allowed to be placed on the market in countries and states
around the world. In the United States specific limits must be met
for volatile organic compounds (VOCs). At the time of writing, the
strictest of these limits is the South Coast Air Quality Management
District Rule 1113. In order to meet the requirements of this Rule,
liquid applied, vapour permeable air and water barrier coatings
must have VOCs less than 50 g/L in order to be used in areas
regulated by SCAQMD. The material as hereinbefore described has a 1
gram of VOCs per litre of material when measured using the
exclusive method and 2 g/L inclusively. Many other materials
(especially those which are solvent based) do not meet this
requirement, but the present composition has a VOC of <2 g per
litre in accordance with (US Environmental Protection Agency (EPA)
Method 24.
[0093] Whilst the majority of commercially available coatings cure
to a minimum 40 mil (1.016 mm) thickness and often require even
thicker coatings the present invention may be coated on a substrate
at a thickness of 10 mil (0.254 mm) to 30 mil (0.762 mm) and still
meets all necessary tests as will be noted in the following
examples avoiding problems encountered with many commercial
alternatives which require significantly thicker coatings (e.g.,
>50 mil (1.27 mm)) especially as it is recognised that very
thick coatings of air/water barriers can interfere with diffusion.
It is to be noted that the present composition contains a pre-cured
polysiloxane network prior to application and as such the coating
is applied and merely dries on the substrate rather than having the
additional need to cure. The composition as hereinbefore described
is suitable for providing an evenly distributed coating across the
whole surface of a substrate, even when said substrate has an
uneven surface and/or is porous.
[0094] The coating composition as described herein, when applied
onto a substrate, provides substrates with long-term protection
from air and water infiltration, normal movement imposed by
seasonal thermal expansion and/or contraction, ultra-violet light
and the weather. It maintains water protection properties even when
exposed to sunlight, rain snow or temperature extremes. Indeed the
composition when tested in accordance with ASTM 1970-09, section
8.6 for low temperature flexibility using a sample having a 15 mil
(0.381 mm) coating thickness, passed the test proving that the
composition, once applied, remains flexible at low
temperatures.
[0095] One particular advantage over other products is that the
coating composition as described herein, when applied onto a
substrate, may be exposed for an extended or even indefinite period
of time prior to the application of exterior cladding.
[0096] The present invention will now be described in detail by way
of the following Examples in which all viscosity measurements were
taken at 25.degree. C. using a recording Brookfield viscometer with
Spindle 3 at 2 rpm according to ASTM D4287-00 (2010) unless
otherwise indicated.
Preparation of Composition
[0097] The preformed silicone latex emulsion was prepared by
introducing about 2 parts by weight of
##STR00004##
(where each R.sup.4 group is a methyl group) into 100 parts by
weight of a hydroxyl dimethyl silyl terminated polydimethylsiloxane
having a viscosity of 50,000 mPas at 25.degree. C. using a
recording Brookfield viscometer with Spindle 3 at 2 rpm according
to ASTM D4287-00 (2010) in a Turrello mixer. 4 parts of a 1:1
solution of water and surfactant (TERGITOL TMN-10) were then added
and the resulting mixture was mixed until a high solids emulsion
gel was formed. The resulting pre-formed silicone latex emulsion
was then suitable for mixing with the other ingredients of the
composition.
[0098] A composition as hereinbefore described was then prepared by
mixing the following ingredients together:
40.8 wt % of the previously prepared preformed silicone latex
emulsion 23.14 wt % of colloidal silica 9.72 wt % ultrafine calcium
carbonate 9.72 wt % Dupont Ti-PURE.RTM. R-706 titanium dioxide
pigment 14.3 wt % water 0.75 wt % TERGITOL TMN-10 surfactant 0.91
wt % of rheology modifier 0.66 wt % of antifoam
[0099] Once the composition was thoroughly intermixed it was
de-aired under vacuum and filtered prior to use.
Air Permeance
[0100] Samples of the composition prepared as described above were
then applied onto an air permeable polyethylene (PE) substrates in
the case of 8 mil (0.2032 mm) samples and polyethylene substrates
in the case of 15 mil (0.381 mm) thickness samples and allowed to
dry to the thickness values identified in Table 1 below. The
resulting dry silicone elastomeric coatings were removed from
respective substrates and tested according to ASTM E2178-11,
Standard Test Method for Air Permeance of Building Materials (i.e.
the rate of air flow (L/s), per unit area (m.sup.2) of a material
per unit static pressure differential (Pa)), however the test
pieces used for the 8 mil (0.02032 mm) thickness samples had an
overall size of 360 mm length.times.360 mm (width) instead of
1m.times.1m specified. A scaled pressure chamber with an internal
opening of 305 mm.times.305 mm was therefore used to conduct the 8
mil (0.2032 mm) thickness samples. The 15 mil (0.381 mm) thickness
samples were measured in complete accordance with ASTM E2178-11,
Standard Test.
TABLE-US-00001 TABLE 1a Air Permeance Results at a variety of
differential Pressures for 8 mil (0.2032 mm) thickness sample:
Differential Pressure (Pa) Air Permeance (L/s per m.sup.2) 25
0.0012 50 0.0021 75 0.0029 100 0.0037 150 0.0052 300 0.0096 100
0.0038 75 0.0029 50 0.0020
[0101] Current building codes typically set the value required to
be below is 0.02 L/s per m.sup.2 at a pressure differential of 75
Pa and as such it will be appreciated that the composition as
hereinbefore described even at significantly higher differential
pressures serves as an air barrier. It should also be appreciated
that the thickness of the material at which this coating meets this
standards is thinner than a majority of the typical materials used
in this market.
TABLE-US-00002 TABLE 1b Air Permeance Results at a variety of
differential Pressures for 15 mil (0.381 mm) thickness sample:
Differential Pressure (Pa) Air Permeance (L/s per m.sup.2) 25
0.00144 50 0.00312 75 0.00494 100 0.00682 150 0.01086 300 0.02428
100 0.00688 75 0.00504 50 0.00326
[0102] As with the 8 mil (0.2032 mm) thickness samples it will be
appreciated that the composition as hereinbefore described even at
significantly higher differential pressures serves as an air
barrier. In this instance the sample was prepared on an air
permeable fibreboard in order to withstand the rigors of the test.
It will be appreciated that there is a higher probability of
pin-holes in the fibreboard material that will result in the higher
air permeability. Also, due to the nature of the fibreboard, it is
more difficult to ensure such a thin film thickness. Fibreboard
absorbs some of the material.
Water Vapour Transmission Rate
[0103] In addition the same silicone latex emulsion was tested
according to ASTM E96/E96M-10, Standard Test Method for Water
Vapour Transmission Rate of Materials (i.e. the steady water vapor
flow in unit time through unit area of a body, normal to specific
parallel surfaces, under specific conditions of temperature and
humidity at each surface.
TABLE-US-00003 TABLE 2a Water Vapour Transmission Results using a
sample as hereinbefore described in accordance with ASTM
E96/E96M-10: Water Vapour Transmission Water Vapour Transmission
Thickness Dry Cup Desiccant Method Wet Cup Water Method (mil/(mm))
(US Perm (ng/Pa s m.sup.2)) (US Perm (ng/Pa s m.sup.2)) 10 (0.254)
7.16 (409.65) 30.34 (1735.86) 15 (0.381) 7.03 (402.21) 24.26 (1388)
20 (0.508) 4.77 (272.91) 19.97 (1142.56)
[0104] The above values were compared with published values for
commercial products according to the publically available data from
the Air Barrier Association of America in relation to water vapour
transmission values measured in accordance with ASTM E96/E96M-10
which are provided in Table 2b below:
TABLE-US-00004 TABLE 2b Water Vapour Transmission Results of
Commercial Products inaccordance with ASTM E96/E96M-10 as available
from the Air Barrier Association of America: Water Vapour
Transmission Water Vapour Transmission Dry Cup Desiccant Method Wet
Cup Water Method Commercial Product (US Perm (ng s.sup.-1 m.sup.-2
Pa.sup.-1)) (US Perm (ng s.sup.-1 m.sup.-2 Pa.sup.-1)) Momentive
SilShield AWB 4.273 (244) 5.493 (314) @ 26 mils (0.66 m) (wet) WR
Grace Penn-A-Barrier VP 0.60 (34.39) 12.9 (741.6) @ 40 mils (1.016
mm) (dry) Henry Air Bloc 31 MR 0.57 (32.0) 36.12 (2066) @ 44 mils
(1.12 mm) (dry) Henry Air Bloc 32MR 0.23 (13.0) 1.02 (58) @ 118
mils (3.00 mm) (wet) Henry Air Bloc 33 MR 0.34 (19.0) 11.4 (652) @
59 mils (1.50 mm)(dry) Henry Air Bloc 06 WB 0.34 (19.0) 11.4 (652)
@ 59 mils (1.50 mm) (dry) Carlisle Barritech VP 0.719 (41.1) 14.295
(817) @ 60 mils (1.524 mm) (wet) [40 mils (1.016 mm) (dry)] BASF
Enershield HP 0.10 (5.81) 17.6 (1004) @ 10 mils (0.254 mm) (wet)
Dupont - Tyvek Fluid Applied 11.48 (656) 24.23 (1384) WB @ 10 mils
(0.254 mm) (wet) Prosoco R-Guard Spray Wrap .RTM. 0.12 (6.86) 3.54
(202) 12 mils (0.305 mm) (wet) Warnock Hersey Sto Gold 0.12 (6.86)
3.54 (202) Coat @ 12 mils (0.305 mm) (wet)
[0105] It is important to note that the Water Vapor Permeance value
of the material as depicted in Table 2a, when tested using the
desiccant cup method, is greater than other materials in the market
(depicted in Table 2b), including the material found in Momentive
SilShield.TM. which is believed to be the commercial product
manufactured by the proprietors of WO2012/064611, Industry
scientists have argued that the desiccant method is more realistic
than the wet cup method because it relies on the transfusion of
vapour from the air through the material and not on a standing cup
of water to ensure diffusion of water through the material. The wet
cup method allows water droplets to form on the underside of the
material being tested; this allows vapour to move through the
material via direct contact. The material is not typically found in
areas with standing water in this application. ICC-ES AC38 for
building wrap materials used in the same application require only
the desiccant test method for these same reasons.
Self Sealability
[0106] Further samples of coated substrate were analysed in
accordance with the Self Sealability (Head of Water) Test described
in Section 8.9 of ASTM D1970-09. This test describes nail
sealability requirements of bituminous roofing systems but is a
commonly used standard for air barrier materials. The test was
carried out on samples prepared as required by the Test Method, at
several coating thicknesses of the dried coating as hereinbefore
described and each coating passed the test as indicated in Table 3
below:
TABLE-US-00005 TABLE 3 Thickness mil (mm) Self Sealability 10
(0.254) Pass 15 (0.381) Pass 20 (0.508) Pass
[0107] Elastomeric materials do not innately have a self-sealing
property. By definition, elastomeric materials will return to their
original state after being stressed within its elastic range, but
that does not mean that the material will return back to its
original state after the elastic range has been surpassed and the
material has torn. The fact that the material as hereinbefore
described is a pre-cured silicone emulsion that dries and does not
cure upon application, was originally considered to render it very
likely to fail the above test because it was not anticipated that
the material would keep a tight enough seal to maintain the
required water head once the dried matrix of the material was
broken by a nail applied during the test, especially at such low
thicknesses as depicted in Table 3 above. In comparison the
material described in WO2012/064611 differs in that it is a
material which cures subsequent to application.
Flame Spread and Smoke Developed Indices Based Upon a Single Test
Conducted in Accordance with ASTM E 84-12a The method, designated
as ASTM E 84-12a "Standard Method of Test for Surface Burning
Characteristics of Building Materials", is designed to determine
the relative surface burning characteristics of materials under
specific test conditions. Results are expressed in terms of Flame
Spread Index (FSI) and Smoke Developed (SD).
[0108] A composition as hereinbefore described was applied onto a
0.25 inch (6 mm) reinforced fibreglass cement board substrate to a
thickness of approximately 15 mil (0.381 mm) The following tests
were carried out in accordance with ASTM E 84-12a excepting that
whilst Section 5.1.9.1 of ASTM E 84-12a specifies a single
combination of lamp and photocell to create the requisite
photometer system, in the present test a specially-designed, modern
photometer system that is utilized by many other tunnel systems
worldwide was used.
Test Results
[0109] Flame Spread Index (FSI) gave a value of 10 and Smoke
Developed (SD) gave a value of 85.
[0110] The air leakage of a sample air barrier comprising the
composition as hereinbefore described was determined in accordance
with ASTM E2357-11 (standard test method for determining air
leakage of air barrier assemblies in US) and it gave the results of
0.000007 cfm/ft.sup.2 at 1.57 psf (75.2 Pa) and 0.00003 L/s per
m.sup.2 at 75 Pa. The assembly was also tested in accordance with
CAN/ULC-5742 and it gave the results of a Class 1A rating. ASTM
E2357-11 is utilized in an attempt to mimic real world conditions
by preparing two exterior wall mock-ups with one mock-up being a
simple wall assembly with sheathing joints and the other being
constructed with sheathing joints; roof and foundation tie-ins;
brick ties, window openings; and electrical, pipe and ductwork
penetrations. Each of the tie-ins and penetrations is fully sealed
with sealant and/or pre-cured extrusions and flashed to the air
barrier assembly to ensure it can withstand the simulated
conditions. Then both wall mock-ups were exposed to positive and
negative sustained wind loads as identified within the test
method.
* * * * *