Note: Descriptions are shown in the official language in which they were submitted.
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WATER REPELLENT COMPOSITIONS, PROCESSES AND
APPLICATIONS THERE<'OR
BRIEF SUMMARY OF THE INVENTION
This invention relates to water repellent compositions and objects which have
been
s treated with said water repellent compositions. This invention also relates
to a process for
producing a water repellent composition, a process for imparting water
resistance to an
object and a process for producing a water resistant object. This invention
also relates to
objects and applications utilising said compositions and processes.
BACKGROUND OF THE INVENTION
io Water repellent compositions are useful for imparting water resistance to a
variety
of objects. In particular, these objects include panels and blocks used in the
building
industry. The panels and blocks used in the building industry include gypsum
board,
plaster board, wall board, gypsum fibreboard, large hollow-core wall panels,
bricks,
blocks and the like. However, it will be appreciated that water repellent
compositions are
~ 5 also useful for a wide variety of objects including foodstuffs, cosmetics,
packaging
materials and other items.
In particular, the aforesaid panels and blocks suffer from the disadvantage
that upon
water absorption there is a loss of desired properties such as strength, fire
retardancy,
sound shielding properties, etc.
zo In particular, building panels and blocks such as plasterboard, gypsum
board or
wallboard as it is otherwise known, gypsum fibreboard, hollow-core panels and
blocks
are produced by the reaction of anhydrous calcium sulphate or calcium sulphate
hemihydrate with water and allowing the mixture to hydrate or set as calcium
sulphate
dihydrate which is relatively hard.
z~ Building panels such as plasterboard, gypsum board or wallboard usually are
formed from a core of set gypsum which is positioned between a pair of outer
liners
which form the respective outer faces of the building panel. The pair of outer
liners are
~~enerally made from paper or fibreglass.
Gypsum fibreboard is formed from a core of set gypsum which contains a fibrous
ao reinforcement of randomly dispersed cellulosic or glass fibres or the like.
The gypsum
core may be positioned on one liner of paper or fibreglass, or positioned
between two
liners, or cast on a belt without any liners whatsoever, in which case the set
gypsum
composition forms the surfaces of the finished panel.
Large scale hollow-core panels are formed from a core of set gypsum which may
or
3s may not contain fibrous reinforcement, and may or may not be cast on a
liner or
positioned between two liners. The panel is cast in a mould with hollow tubes
positioned
in it that are removed after the gypsum has set. These large scale hollow-core
panels are
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WO 00/63294 2 - PCT/AU00/00331
commonly used as structural load-bearing wall components for internal and
external
walls.
Bricks and blocks are formed from set gypsum which may contain cellulosic or
tibreglass reinforcement or the like. The bricks or blocks are cast in moulds.
s In use, these building panels and blocks are commonly exposed to water and
since
set gypsum readily absorbs water, such water absorption leads to the
deleterious effect
mentioned previously, i.e. loss of strength, fire retardancy, etc.
Whilst there are water repellent compositions known to coat such products, it
has
heen surprisingly discovered that the use of the water repellent composition
of this
~ o invention provides enhanced water resistance to objects. Further, the use
of the water
repellent composition of this invention can lead to the benefit of increased
throughput of
production of building panels which are water resistant since less water may
be required
in the formation of the panel.
This invention seeks to ameliorate the disadvantages of the known water
repellent
~ ~ compositions by imparting improved water resistance, or at least provide a
useful
alternative.
SUMMARY OF THE INVENTION
According to a first embodiment of this invention, there is provided a water
repellent composition comprising:
Zo a) a wax; and
h) a styrene (meth)acrylic copolymer comprising at least some active hydrogen.
According to a second embodiment of this invention, there is provided a water
repellent composition comprising:
a) a wax;
2s h) a styrene (meth)acrylic copolymer comprising at least some active
hydrogen; and
c) a protective colloid compound.
The water repellent composition of the first or second embodiment may further
comprise
d) an alkaline compound.
ao In particular, according to a third embodiment of this invention, there is
provided a
water repellent composition comprising:
a) a wax;
b) a styrene (meth)acrylic copolymer comprising at least some active hydrogen;
c) a protective colloid compound; and
s5 d) an alkaline compound.
According to a fourth embodiment of this invention, there is provided a water
repellent composition comprising:
a) a wax;
b) a styrene (meth)acrylic copolymer comprising at least some active hydrogen;
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c) a polyvinyl alcohol having a saponiftcation degree of at least 75 mol % ;
and
d) an alkaline compound.
The water repellent compositions of the invention may further comprise
e) a hydrocarbon resin.
s In particular, according to a fifth embodiment of this invention, there is
provided a
water repellent composition comprising:
a) a wax;
b) a styrene (meth)acrylic copolymer comprising at least some active hydrogen;
c) a polyvinyl alcohol having a saponification degree of at least 75 mol % ;
i o d) an alkaline compound; and
e) a hydrocarbon resin.
According to a sixth embodiment of this invention, there is provided a water
resistant object comprising an object and the water repellent composition
according to any
one of the first to fifth embodiments of this invention.
According to a seventh embodiment of this invention, there is provided a water
resistant gypsum composition comprising gypsum and the water repellent
composition
according to any one of the first to fifth embodiments of this invention.
According to an eighth embodiment of this invention, there is provided a
shaped
uhject comprising the water repellent composition according to any one of the
first to fifth
zo embodiments of this invention.
According to a ninth embodiment of this invention, there is provided a panel
comprising the water repellent composition of any one of the first to fifth
embodiments of
this invention.
According to a tenth embodiment of this invention, there is provided a panel
zs comprising the water repellent composition of any one of the first to fifth
embodiments of
this invention wherein the panel is plasterboard, gypsum board, wallboard,
gypsum
fihreboard, large hollow-core gypsum panel or the like.
According to an eleventh embodiment of this invention, there is provided a
layered
product comprising:
ao i) at least one liner; and
ii) a water resistant set gypsum comprising the water repellent composition of
any one of the first to fifth embodiments of this invention.
According to a twelfth embodiment of this invention, there is provided a
layered
product comprising:
35 1) a first liner and a second liner;
ii) a water resistant set gypsum comprising the water repellent composition of
any one of the first to fifth embodiments of this invention positioned such
that the water
resistant ;ypsum is between the first liner and the second liner.
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According to a thirteenth embodiment of this invention, there is provided a
panel
comprising the layered product of either the eleventh or twelfth embodiments
of this
invention.
According to a fourteenth embodiment of this invention, there is provided a
s plasterboard comprising the layered product of the eleventh or twelfth
embodiments of
this invention.
According to a fifteenth embodiment of this invention, there is provided a
process
for forming a water resistant object comprising the steps of applying a water
repellent
composition according to any one of the first to fifth embodiments of this
invention to an
~ o object.
According to a sixteenth embodiment of this invention, there is provided a
process
t«r torming a water resistant panel comprising the steps of applying a water
repellent
composition according to any one of the first to fifth embodiments of this
invention to a
panel.
~ s According to a seventeenth embodiment of this invention, there is provided
a
process for forming a water resistant plasterboard, gypsum board or the like
comprising
the steps of applying the water repellent composition according to any one of
the first to
fifth embodiments of this invention to a plasterboard, gypsum board or the
like.
According to an eighteenth embodiment of this invention, there is provided a
zo process for producing a gypsum plasterboard comprising the steps of
(i) forming a stucco slurry from gypsum rock; and
(ii) adding a water repellent composition of any one of the first to fifth
embodiments of this invention to the stucco slurry to form a treated stucco
slurry;
and
2~ (iii) forming a gypsum plasterboard from the treated stucco slurry.
According to a nineteenth embodiment of this invention, there is provided a
water
resistant object formed from applying the water repellent composition of any
one of the
first to fifth embodiments of this invention to an object.
Typically a surfactant is added as a further component to the composition of
any one
so ~f the first to fifth embodiments of this invention.
DETAILED DESCRIPTION OF THE INVENTION
Throughout this specification, unless the context clearly indicates otherwise,
the
words "comprise", "comprises", "comprising" or other variations thereof shall
be
understood as meaning that the stated integer is included and does not exclude
other
35 inte~~ers from being present even though those other integers are not
explicitly stated.
As used herein, the expression "styrene (meth)acrylic acid copolymer" refers
to
collymers which predominantly comprise copolymerised styrene and acrylic acid
and/or
methacrylic acid, and includes within its meaning such copolymers which
include other
cumonomers and/or in which the carboxyl groups of the acrylic or methacrylic
acid residues
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WO 00/63294 5 ~ PCT/AU00/00331
are partially esterified. Thus the styrene (meth)acrylic copolymer includes at
least some free
carboxyl groups and therefore includes at least some active hydrogen.
As used herein, the expression "water resistant" refers to an object which has
been
treated so that when contacted with water the object does not degrade as
rapidly as would
s the same object which had not been so treated.
Typically, the component a) wax in the water repellent composition is a
paraffin
wax, slack wax, polyolefin wax, ozokerite wax, ceresin wax. Still typically,
the wax has
a melting point in the range of 40 to 90° Celsius. Still more
typically, the wax is a
paraffin wax or polyolefin wax. The wax acts as a primary waterproofing agent
in the
~ o water repellent composition. The component a) wax may also be a mixture of
two or
more of the aforesaid types of waxes.
Typically, the component b) styrene (meth)acrylic copolymer comprising at
least
some active hydrogen in the water repellent composition is a copolymer of
styrene and
acrylic acid or methacrylic acid. The acrylic acid or methacrylic acid may be
partially
~ ~ esterified. The esteritication of the styrene (meth)acrylic acid copolymer
is achieved by
use of fatty acid alcohols, typically C1-C15 fatty acid alcohols.
Typically, the weight average molecular weight of the styrene (meth)acrylic
acid
copolymer is S00 to 100,000, still more typically 1000 to 90,000, 1500 to
50,000, 1500
to 30.000, 1500 to 20,000, or 1500 to 10,000 and more typically 1800 to 8500.
2o Typically, the styrene (meth)acrylic acid copolymer is in its salt form.
The styrene (meth)acrylic acid copolymer acts as a dispersing agent which
provides
hotter dispersion in the water repellent composition. The styrene
(meth)acrylic acid
copolymer typically forms a substantially insoluble water impervious film on
an object
thereby imparting water resistance to the object. Typically, in applications
utilising
z~ panels such as gypsum board, wall board and plaster board, the styrene
(meth)acrylic acid
copolymer also enhances the bonding of liner papers to the core of the panel.
The use of
styrene (meth)acrylic acid copolymer is compatible with other dispersants and
additives
used in water repellent compositions.
Cxamples of alkali soluble, acid containing copolymers useful as the styrene
ao (meth)acrylic acid copolymer in the compositions of this invention are:
styrene-acrylic acid
copolymers, styrene-methacrylic acid copolymers, styrene-acrylonitrile-acrylic
acid
copolymers. styrene-butyl acrylate-acrylic acid copolymers, and the like. The
styrene may
he partially replaced with other hydrophobic monomers such as alpha-
methylstyrene; alkyl
substituted styrenes such as vinyl toluene; acrylonitrile; vinyl chloride:
acrylic- and
3~ methacrylic esters. such as butyl acrylate, methyl methacrylate and the
like, or mixtures
thereon: vinyl esters. such as vinyl acetate or vinyl laurate: fumarate
esters, such as dibutyl
f'umarate: itaconate esters, such as dibutyl itaconate; olefins, such as
ethylene, and the like,
or mixtures thereof. In place of part of the acrylic or methacrylic acid,
other
copolvmerizable, unsaturated acids may be used in the synthesis of styrene
(meth)acrylic
ao acid copolymer. Examples of such copolymerisable unsaturated acids are
crotonic acid,
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WO 00/63294 6 PCT/AU00/00331
itaconic acid and the like. Unsaturated sulfonic acids, such as vinyl sulfonic
acid or styrene
sulfonic acid and the like may also be used.
The acid number of the styrene (meth)acrylic acid copolymer is at least 100
and
generally ti-om 100 to 400, preferably from 190 to 250. When a styrene-acrylic
acid
s copolymer is used in the compositions of this invention the weight ratio of
styrene to acrylic
acid is generally from about 6:1 to about 1.5:1, preferably from about S:1 to
about 2.5:1.
The styrene (meth}acrylic acid copolymer can be any of the commercially
available
products. such as Morez I01, sold by Morton Chemical Company, or Flexbond 25,
sold by
the Air Products Co., or Joncryl 678 sold by S. C. Johnson Company. Some of
these
io commercial copolymers are available as aqueous solutions and can be used in
the
compositions of the invention as such. If they are in a solid form they have
to be dissolved
in an alkaline medium at elevated temperature. Alkali compounds such as
ammonium
hydroxide. sodium hydroxide, potassium hydroxide, soda ash and the like, as
well as water
soluble mono-, di- and trialkyl- or hydroxyalkyl amines, such as methyl or
ethyl amine or
~ ~ monoethanolamine, may be employed to solubilize the styrene (meth}acrylic
acid
copolymer. The pH of the solution of the styrene (meth)acrylic acid copolymer
is generally
about from G to 10, preferably from about 7.5 to 9. The aqueous styrene
(meth}acrylic acid
copolymer solution generally has a solids level of from 20 to 40% w/v.
Typically, the water repellent composition further comprises other additives
such as
zo dispersing agents, emulsifiers, buffers, surfactants, wetting agents,
thickeners, etc.
Typically, the dispersant is selected from the group such as lignosulphonates
and aldehyde
based dispersants. Suitable buffering agents include potassium carbonate,
sodium
carbonate and lithium carbonate. Suitable surfactants include sulfonated
petroleum
derivatives and their salts, sulfonated carboxylic acids and their salts,
ethylene oxide
z~ modified surfactants, and fluorine modified surfactants.
Typically, the water repellent composition further comprises one or more
wetting
agents selected from fluorine modified wetting agents, silicon containing
wetting agents
and ethylene oxide modified wetting agents.
Typically, the water repellent composition further comprises one or more
thickeners
3o selected from natural or modified gums, methyl, ethyl or propyl cellulose,
hydroxyethylcellulose and hydroxypropyl cellulose.
Typically, the component c) protective colloid compound in the composition of
the
second and third embodiments is a polyvinyl alcohol, a natural or modified
gum. The
polyvinyl alcohol is more typically a partially or fully hydrolysed alcohol,
still more
35 typically in the range of 75 to 100% hydrolysed. The typical viscosity of
the polyvinyl
alcohol is 3 to 50 centipoise when tested as a 4 % aqueous dispersion.
Typically, the component d) alkaline compound in the composition of the third,
fourth and fifth embodiments is a water soluble compound and is selected from
the group
of alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and
potassium
ao hydroxide; alkali metal carbonates such as sodium carbonate and potassium
carbonate;
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ammonia; ammonium hydroxide; amines such as dimethylamine, trimethylamine and
triethylamine; and ethanolamines such as triethanolamine, diethanolamine,
dimethylethanolamine and methyldiethanolamine. Typically, the alkaline
compound is
added in an amount of from 0.3 to 3 times the amount required for neutralising
the
s styrene (meth)acrylic acid copolymer.
Typically, the component e) hydrocarbon resin in the composition of the fifth
embodiment is a petroleum resin such as a coumarone-indene resin having a
molecular
weight of from 500 to 3000 obtainable by polymerising a Cg aromatic
hydrocarbon or CS
aliphatic hydrocarbon fraction obtained from the refinery of petroleum or from
a process
~ o of a petroleum chemical industry, by way of a Friedel-Crafts catalyst; a
terpene resin
having a molecular weight of from 500 to 3000 obtainable from turpentine oil;
rosin; a
homopolymer or copolymer of ethylene, propylene, butene, isobutylene or
styrene having
a molecular weight of from 500 to 30 000 and a melting point of at least
95° C, or
asphalt. The hydrocarbon resins used in the present invention may also
includes other
~ ~ atoms such as oxygen.
The weight percent of component a) wax in respect of the total weight of
components a) to e) of the water repellent compositions is:
typically 20 to 99.5 percent by weight,
more typically 25 to 99.5 percent by weight,
zo still more typically 30 to 95 percent by weight,
even more typically 35 to 90 percent by weight,
yet more typically 40 to 85 percent by weight.
The following Table A provides typical weight ratios of the component a) wax
to
the component b) styrene (meth)acrylic copolymer in the water repellent
composition of
z5 this invention.
Table A
Wax (parts Styrene (meth)acrylic copolymer containing at least
by some active
weight) hydrogen (parts by weight)
1 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02,
0.03, 0.04, 0.05,
0.06, 0.07, 0.08, 0.09, 0.10, 0.15, 0.20, 0.25,
0.30, 0.40, 0.50,
0.60, 0.70, 0. 80, 0. 90, 1.0, 1.1, 1.2
Typically, the weight ratio of the component a) wax to the component b)
styrene
(meth)acrylic copolymer of this invention is selected within the range of from
1 to 0.005
to 1 to 0.3, more typically 1 to 0.005 to 1 to 0.2, still more typically 1 to
0.01 to 1 to
so 0.1.
The weight percentage range of component b) styrene (meth)acrylic acid
copolymer
in respect of the total weight of components a) to e) of the water repellent
compositions
ls:
typically 0.5 to 60 percent by weight,
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more typically 0.5 to 50 percent by weight,
still more typically 0.5 to 40 percent by weight,
even more typically 0.5 to 30 percent by weight,
yet more typically 0.5 to 20 percent by weight,
s most typically 1.0 to 10 percent by weight.
The weight percentage range of component c) protective colloid compound, when
present, in respect of the total weight components a) to e) of the water
repellent
compositions is:
typically 0.1 to 20 percent by weight,
more typically 0.5 to 15 percent by weight,
still more typically 0.75 to 10 percent by weight,
even more typically 0.75 to 7.5 percent by weight
yet more typically 1.0 to 5 percent by weight.
The weight percentage range of component d) alkaline compound, when present,
in
~ ~ respect of components a) to e) of the total weight of the water repellent
compositions is
typically 0 to 10 percent by weight,
more typically 0.1 to 10 percent by weight,
still more typically 0.1 to 7.5 percent by weight,
even more typically 0.1 to 5.0 percent by weight.
zo The weight percentage range of component e) hydrocarbon resin, when
present, in
respect of the total weight of components a} to e) of the water repellent
compositions is
typically 0 to 10 percent by weight,
more typically 0.1 to 10 percent by weight,
still more typically 0.5 to 7.5 percent by weight,
zs even more typically 0.5 to 5.0 percent by weight,
and yet more typically is dependent upon the required water resistance for the
desired
ohject to be treated with the water repellent composition.
Typically, further compatible waxes, polymers, resins and additives may be
added
to the water repellent composition to achieve desired properties as may be
envisaged for
so various types of objects. More typically, a water soluble polymer such as a
polyacrylamide, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose
or
hydroxypropylcellulose may be incorporated into the water repellent
composition.
In an illustrative process for preparing one water repellent composition of
the
invention, paraffin wax with a melting point between 40°C and
90°C is heated in a tank to
a~ 1?0°C and a petroleum resin with a softening point of 95 to
100°C is dissolved in it. In a
second tank, polyvinyl alcohol is dispersed in water and heated to 95°C
to dissolve it. A
solution of styrene acrylic resin dissolved in water with the aid of an
alkaline compound is
added to the polyvinyl alcohol solution, together with such other additives as
may be
reduired to impart further desirable properties to the emulsion to be formed.
Preferred
ao syrene acrylic resins are commercially available as JONCRYL 678 or JONCRYL
682 (S.
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C. Johnson & Co.) or MOREZ 100 or MOREZ 101 (Morton Polymers) The water
solution
containing polyvinyl alcohol and styrene acrylic resin, and the wax solution
containing
petroleum resin are combined to form an emulsion with the aid of suitable
emulsification
equipment.
s Typical processes for production of the water repellent composition comprise
phase
reversal emulsification or mechanical emulsification. These methods may be
used alone
or in combination. The mechanical emulsification may be conducted by a
homomixer, a
valve homogenises, a colloid mill or a supersonic method, or any other
suitable method.
The water repellent composition is useful for improving the water resistance
of
~ o objects including fibres, papers, cardboard, wood materials or synthetic
wood materials
(particle boards and fibreboards); cosmetics; aggregate materials such as
concrete, gravel
or the like; and foodstuffs such as fruit, particularly apples. Typically, the
water
repellent composition is used for plasterboard, wallboard or gypsum board,
gypsum
tibreboard, large scale hollow-core gypsum panels, and gypsum bricks and
blocks.
~ s In the processes of the fifteenth, sixteenth, seventeenth and nineteenth
embodiments
of the present invention the step of applying the water repellent composition
may involve
any convenient application method. For example, the application may be by
spraying,
rolling, brushing, dipping or curtain coating. If desired, selected areas of
objects such as
panels may have the water repellent composition applied to them by printing
techniques
zo such as transfer rolling or screen printing.
Typically, the water repellent composition is an aqueous emulsion and a
sufficient
amount of water is added to the components a), b) and c) to e) when present,
as required
for the particular application required. Usually, the ratio of the weight of
water to the
total weight of components a) to e) is about 1:1 but this may be varied to
suit the desired
zs application. Typically, suitable solubilisers to effect the solution of the
styrene
(meth)acrylic copolymer for use in the emulsion include alkali metal or
ammonium
hydroxides and are typically employed in an amount of 0.05 to 10% , by weight,
of the
emulsion.
The following Table B provides a typical blend proportion of gypsum to the
water
ao repellent composition of any one of the first to fifth embodiments, in a
water resistant
gypsum composition of the seventh embodiment of this invention. Table B
illustrates for
entries numbered 1-24 the blend proportion of gypsum:water repellent
composition iri
parts by weight.
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Table B
Entry Gypsum Water
Repellent
Composition
(parts
by weight)
(parts
by
weight)
1 10 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
2 9.80 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
3 9.75 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
4 9.50 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
9.25 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
6 9.0 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
7 8.75 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
8 8.50 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
9 8.25 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
8.00 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
I1 7.75 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45Ø5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
12 7.50 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
13 7.25 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
14 7.00 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
6.75 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
16 6.50 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
17 6 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
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WO 00/63294 ~ ~ PCT/AU00/00331
18 5.75 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
19 5.5 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
20 5 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
21 4 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5, 2Ø
1.75,
22 3 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5,1.0,1.25,
0.1,
1.5.
23 2 0.05, 0.15,0.2,0.25,0.3,0.35,0.4,
0.1, 0.45,
0.5,
1Ø
24 1 0.05,0.1,0.15,0.2,0.25,0.3,0.35,0.4,0.45,0.5.
Typically, gypsum is added to a water repellent composition of this invention
comprising the following components:
a) a wax having a melting point of 40 to 90° C;
h) a styrene (meth)acrylic acid copolymer;
s c) a protective colloid compound; and
d) an alkaline compound.
More typically e) a hydrocarbon resin is also added.
Typically, the gypsum is added in an amount of 50 to 99.5 % by weight, more
typically GO to 99.5 % by weight, still more typically 70 to 99.5 % by weight,
even more
~ o typically 80 to 99.5 % by weight, yet more typically 90 to 99.5 % by
weight, most
typically 92 to 95% by weight, based on the total weight of gypsum and water
repellent
composition.
Gypsum compositions of this invention are settable by hydration to form a
water
resistant gypsum product. Typically the gypsum product is gypsum plaster,
plasterboard,
~ 5 wall board. gypsum fibreboard, large hollow-core gypsum panel, gypsum
brick or block,
or the like.
Typically, gypsum is selected from naturally occurring forms of calcium
sulphate,
tlue gas desulphurisation plant wastes, phosphoric acid manufacturing wastes,
hydrochloric acid manufacturing wastes ete. More typically the gypsum is
extracted from
zo mines or quarry as gypsum rock. Still more typically the gypsum rock is
crushed,
blended with gypsumboard waste and then is screened. During the crushing
process, or
after crushing and screening, the gypsum is dried by suitable means such as
passing
heated air through the crushing mill, or drying in a rotating kiln or oven so
as to
evaporate any surface moisture on the gypsum. Dry gypsum is ground by crushers
or
zs rollers to form a desired particulate size of gypsum.
Usually, the dried gypsum is then calcined by suitable means to remove
chemically
combined water, and so form gypsum hemihydrate.
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Generally, the gypsum hemihydrate is mixed with water, a water repellent
composition of this invention, and such other additives as may be required, to
form a
gypsum slurry. The gypsum slurry so formed is then placed in a mould or
positioned in a
layered product.
s Typically, the settable gypsum composition is set so as to form a set gypsum
product which is water resistant and layered with at least one liner to form a
layered
product. Typically, the water resistant gypsum is positioned in a layered
product
comprising:
a) a first liner;
~ o b) the water resistant gypsum;
c) a second liner.
The layered product may be formed into a shaped product most typically a
panel.
Accordingly, there is also provided a panel comprising:
a) a first liner;
> > b) the water resistant gypsum according to this invention: and
c) a second liner.
Typically, the water resistant gypsum is sandwiched between the first and
second
liners so as to form a layered product and more typically a panel such as
plasterboard,
wallboard or the like. Typically, the first and second liners may be selected
from paper,
2o fibreglass, wood, laminates or other materials commonly used in layered
products. The
shaped products such as panels are useful in the construction industry as
building panels
such as walls, ceilings, etc.
Thus, in another form of this invention, there is provided a method of forming
a
layered product comprising the steps of:
2~ (i) forming a layer of a water resistant gypsum which has been treated with
the
water repellent composition according to any one of the first to fifth
embodiments of this
invention on a first liner;
(ii) disposing a second liner on the water resistant gypsum so that the first
liner is
in an opposed relationship to the second liner and whereby the water resistant
gypsum is
3o positioned between the first and second liners; and
(iii) drying said layered product so as to allow hydration of the gypsum.
Typically, the layered product is formed into a shaped product. More
typically, the
layered product is formed into a panel. Still more typically, the layered
product is formed
into a board especially adapted for the construction industry.
35 Typically, the formation of a panel incorporating the water resistant
gypsum
comprises the following steps:
a) mixing gypsum rock with or without recycled plasterboard;
b) crushing and screening the mixture of gypsum rock and plaster board;
c) drying the gypsum rock and plasterboard to remove excess water;
4o d) calcining the gypsum to form gypsum hemihydrate;
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e) mixing the water repellent composition of any one of the first to fifth
embodiments of this invention with water to form a dispersion; and
t) mixing the gypsum hemihydrate and the dispersion from step (e) to form a
stucco slurry;
g) spreading the slurry between liner papers;
h) allowing the slurry to set to form a panel; and
i) kiln drying the panel.
Still typically, further additives may also be incorporated in the dispersion
of step e)
to provide further strength, fire retardancy, ease of manufacture etc.
~o Advantages in the production of wet area gypsum plasterboard containing the
water
repellent composition of this invention may include reduced water requirement
to obtain a
stucco slurry of suitable consistency, improved bond of the set gypsum core to
the liner
papers covering said core, reduced drier temperatures, reduced energy costs,
improved
hoard quality due to reduced end-burn of boards during drying.
,s BRIEF DESCRIPTION OF TWE DRAWINGS
Figure 1 is a graphical representation of comparative water absorption over
periods of
two hours and twenty four hours in 2.5 centimetre cube specimens of set gypsum
composition containing either Emulsion A or Emulsion D described in the
following
Preparation Examples, or one of two commercially available wax emulsion
waterproofing
zo compounds.
Figure 2 is a graphical representation of comparative water absorption in 2.5
centimetre
cuhe specimens of set gypsum composition containing Emulsion A described in
the
following Preparation Examples or a commercially available wax emulsion
waterproofing
compound.
zs Fi~~ure 3 is a graphical representation of comparative water absorption in
2.5 centimetre
cuhe specimens of set gypsum composition containing Emulsion D described in
the
Hollowing Preparation Examples or either of two commercially available wax
emulsion
waterproofing compounds (Freemulsion 754 and Rhenium).
EXAMPLES
so This invention will now be described, by way of illustration only, with
reference to
the following examples. The examples should not be construed as limiting the
generality
of the above description.
Preparation Example 1
One hundred and ninety six parts of paraffin wax having a meltin l; point of
58°C and
35 ~~ parts of a C~, aromatic petroleum resin with a softening point of
98°C and a bromine
value of 30 were melted at 130°C and the temperature was lowered to
120°C. Separately, 12
parts of polyvinyl alcohol with a saponification degree of 89% were dispersed
in 222 parts
ol~ water and heated to 95°C. To this was added a solution comprised of
4 parts styrene
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WO 00/63294 ~ 4 PCT/AU00/00331
acrylic resin with a molecular weight of 8700 and an acid number of 215, and 1
part of
potassium hydroxide, both dissolved in 15 parts of water. The wax and water
solutions
were combined in a closed dispersion mixer and the mixture was emulsified by
passing it
through a piston type pressure homogenises at 1050 psi (7300kPa). The
emulsified mixture
was then cooled to obtain an emulsion A with a solids content of 50%.
Preparation Example 2
An emulsion having a solids content of 50% was prepared in the same manner as
in
Preparation Example 1, except that 2.5 parts of potassium carbonate were added
to the water
phase prior to combining the wax and water phases to obtain an emulsion B.
~ o Preparation Example 3
An emulsion having a solids content of 50% was prepared in the same manner as
in
Preparation Example 2, except that 1 part of a proprietary diphenol oxide
sulfonate solution
AEROSOL DPOS-45 (Cytec) was added to the water phase prior to combining the
wax and
water phases to obtain an emulsion C.
Preparation Example 4
An emulsion having a solids content of 50% was prepared in the same manner as
in
Preparation Example 1, except 22 parts of a mixed Cy aromatic/Cs aliphatic
petroleum
resin with a softening point of 97°C were dissolved in the wax phase
instead of the C9
aromatic petroleum resin to obtain an emulsion D.
2o Water Absorption
The quantity of water required to prepare a gypsum slurry of normal
consistency
was determined. Gypsum slurries were prepared using various emulsion
waterproofing
additives at 5 % of the dry stucco weight mixed with a suitable amount of
water to give
the same ratios of total liquid to dry stucco, and 25 millimetre cube
specimens were cast
z~ frUnl the prepared slurries. The cubes were dried in an oven at
180°C until they had
reached 75 %a of their initial mass, and then dried at 45 °C for 20
hours. The dried weight
of the specimens was recorded, and they were immersed in water at 23°C.
After 2 hours,
the specimens were reweighed, and the water absorption was determined. The
results are
shown in table C. The gypsum hemihydrate used to prepare the specimens was
from a
ao ~~ypsum plasterboard plant in New Zealand.
2 Hr WATER ABSORPTION
EMULSION DOSE RATE ABSORPTION
EMULSION A 5 % 0.6 %
FREEMULSION 759 5 % 2.2 %n
DIAPROOF GX 5 % 0.7 %
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WO 00/63294 ~ 5 PCT/AU00/00331
.able C
A similar experiment was conducted in which 2.5 cm cubes cast from gypsum
slurries, containing Emulsion A or Emulsion D as described in ,the above
Preparation
Examples or containing Freemulsion 754 or Freemulsion 759, were dried as
described
above and immersed in water for 24 hours. In each case amount of waterproofing
additive was 5 % by weight based on the weight of dry stucco. The water
absorption of
the immersed cube was measured after 2 and 24 hours and the results are set
out in Table
D below and otted in Figure
are pl 1.
Percent
(w/w)
water
absorption
after:
2 hours 24 hours
Freemulsion 754 1.0 8.6
Freemulsion 759 1.1 11.1
Emulsion D 0.8 1.5
Emulsion A 0.8 1.4
Table D
1o Fi~~ure 2 is a graphical representation of comparative water absorption,
over a period of
up to 72 hours, in 2.5 centimetre cube specimens of set gypsum composition
containing
Emulsion A described in the Preparation Examples or Freemulsion 754. Both
emulsions
were dosed at the rated of 8.3 % by weight of dry stucco. The results are set
out in Table
E.
Percent
(wlw)
water
absorption
after:
2 hours 24 hours 48 hours 72 hours
Freemulsion 754 2.1 9.2 10.8 12.8
Emulsion A 1.0 3.1 4.1 4.8
Table E
Freeri~ulsions 754 and 759 are proprietary wax emulsion waterproofing
additives for
plasterboard marketed by PCA Hodgson Chemicals. Diaproof is a proprietary wax
emulsion waterproofing additive produced by Mitsubishi Chemical Corporation,
and
disclosed in Japanese Patent Application Number JP 42164/89 dated February 22,
1989,
zo and subsequent European Patent Application number EP 0 384 322 A1 tiled
February 16,
1990, and United States Patent number 5,098,943 dated March 24, 1992.
Fi'zure 3 is a graphical representation of comparative water absorption in 2.5
centimetre
cube specimens of set gypsum composition containing Emulsion D described in
the
Preparation Examples or either of two commercially available wax emulsion
z5 waterproofing compounds (Freemulsion 754 and Rhenium, a proprietary wax
emulsion
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WO 00/63294 ~ g PCT/AU00100331
waterproofing additive produced by Rhenium Co.) The results are set out in
Table F.
The waterproofing additives were added in amounts of 5 % , 7.5 % or 10 % by
weight of
rhP drv ctuccn_ as indicated.
TreatmentWaterproofing additivePercent
(w/w)
water
absorption
after:
2 hours 24 hours 48 hours72 hours
1 Freemulsion 754 6.6 20.0 21.2 22.6
at 5%
2 Freemulsion 754 2.7 10.4 11.8 12.0
at 7.5%
3 Freemulsion 754 2.0 4.2 5.3 5.6
at 10%
4 Emulsion D at 5% 1.9 3.9 5.0 5.8
Emulsion D at 7.5% 2.3 3.6 4.2 4.9
6 Emulsion D at 10% 2.3 3.9 4.9 5.4
7 Rhenium at 5% 9.0 33.8 22.3 35.3
8 Rhenium at 7.5% 4.8 15.6 10.1 17.3
9 Rhenium at 10% 4.5 7.8 10.6 15.1
Table F
Dispersion
Emulsion based waterproofing additives tend to thicken gypsum slurries,
increasing
the quantity of water required in the mix to achieve normal consistency. This
excess
water must be removed in the drying process, and increases the porosity of the
finished
plasterboard. The dispersing effect observed with waterproofing emulsions
prepared
~ o according to this invention reduces the quantity of water required to
produce a gypsum
slurry of normal consistency.
The water required to prepare a gypsum slurry of normal consistency was
determined by hand mixing gypsum hemihydrate powder with water. The prepared
slurry
was poured into a cylindrical mould 35 millimetres in diameter with a height
of 51
~5 millimetres. The mould was lifted one minute from the addition of the
gypsum
hemihydrate powder to the water, and the diameter of the resulting pat of
gypsum slurry
was measured. Normal consistency was defined as the quantity of water required
to
produce a pat of 10013 millimetres in diameter.
Gypsum slurries were prepared using emulsion based waterproofing additives
mixed
zo with the water to give the same total liquid content as had been previously
determined to
yield a slurry of normal consistency. The diameter of the gypsum paste
resulting from
these slurries indicates the dispersing effect of emulsions prepared according
to this
invention. The results are shown in Table G. The gypsum hemihydrate used was
obtained from a gypsum plasterboard plant in Chile.
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DISPERSION
EMULSION DOSE RATE TOTAL LIQUID DIAMETER
Blank 59g 100m
EMULSION A 5 % 59g 109mm
FREEMULSION 754 5 % 59g 65tnm
Table G
Stucco slurry incorporating the Wax/Styrene acrylic Emulsion has increased
fluidity
when compared to stucco slurry without the emulsion, or when compared to
stucco slurry
containing a commercially available waterproofing wax emulsion. The increased
fluidity
will allow production of wet area gypsum plasterboard with reduced water
content,
improved production efficiencies such as faster line speed and reduced end-
burn of boards
in the drying kiln, and reduced energy costs in the drying kiln due to the
lower drying
temperature required to remove the excess water from the gypsum plasterboard.
~ o Similar slurries were prepared by the same method using gypsum hemihydrate
from
Th 1 ' dd d d t f 5 % b fight of the
Australian sources. a wax
emu sons were a a at a
ose ra a o o y we
dry stucco in each case.
The results are shown in
Table H.
DISPERSION
AUSTRALIAN STUCCO
STUCCO 1 STUCCO 2
BLANK 100mm 100mm
EMULSION A 120mm 103mm
EMULSION B 117mm
EMULSION C 123mm 116mm
EMULSION D 120mm
EMULSION D 112mm
FREEMULSION 754 68mm
FREEMULSION 754 73mm
Table H
Stucco slurries containing emulsions made with styrene acrylic Resin
(Emulsions A
~ ~ to D) clearly show an increase in dispersion when compared to those
containing a
commercially available proprietary wax emulsion waterproofing compound, or
when
compared to stucco slurries containing no wax emulsion. The stucco slurries
will require
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WO 00/63294 ~ g PCT/AU00/00331
less water to attain a suitable consistency for plasterboard production, and
hence the
plasterboard will require less energy to dry.
Production of Gypsum Wallboard
A preferred aspect of this water repellent composition is to form water
resistant
s gypsum plasterboard or wallboard. The following description of an example
illustrates a
typical method of producing wallboard or plasterboard which is water
resistant.
a) Gypsum rock is extracted from a suitable source for example a mine or a
quarry. The extracted gypsum rock is then transported to a plant where the
gypsum rock
is inserted into crushers, blended with reclaimed wasteboard and screened to a
suitable
~ o size typically no more than Scm in diameter.
b) After crushing and screening, the gypsum rock is dried by suitable means
such
as a rotating kiln or oven which evaporates the surface moisture from the
gypsum rock.
c) Once the gypsum rock is dried the gypsum is ground by suitable means such
as rollers.
s d) Plaster is calcined or heated to remove excess water which is chemically
hemded to the gypsum in a kettle calciner or flash calciner to form stucco.
e) Once the stucco is formed it is suitably mixed with other desired additives
such as pearlite, starch, fibreglass or vermiculite so as to provide a range
of properties,
for example, fire retardancy, sound proofing, etc.
2o t) Water is then added together with the water repellent composition as
described
in any one of the Preparation Examples 1 to 4 above, and soap foam and
accelerators in a
mixing vessel at the beginning of a board forming line after suitable mixing.
The resulting slurry is disposed between two paper sheets which also act as a
mould.
2s h) The stucco slurry is sandwiched between the two paper sheets and allowed
to
set su as to form the water resistant gypsum layer between the two outer
sheets or liners.
i) The resulting layered product is formed into a long continuous sheet or
wallboard and placed on a conveyor and roller where it is cut after the stucco
slurry has
hardened.
3o j) The cut boards are subjected to further drying and heating in a multi-
stage
kiln.
k) The resulting wallboard is then ready for transportation.
Modifications and variations such as would be apparent to a skilled addressee
are
deemed to be within the scope of this invention. It is also understood that
the scope of
35 this invention should not be limited to the examples or drawings
illustrated above.
