Note: Descriptions are shown in the official language in which they were submitted.
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A System Using a Drywall Board and a Jointing Compound,
Coating for Wall construction
Field of the Invention
[0001] Compatible coating formulation and jointing material systems for
improved drywall installation are provided, as well as a coating and coating
formulation for improved drywall installation. A method for constructing
interior
walls including applying the coating and jointing material systems and
interior
construction systems formed with the use of the coating and jointing materials
are further provided, as well as a method for constructing interior walls
including
applying the coating and jointing material systems and interior construction
systems formed with the use of the coating.
Back round
[0002] Interior walls typically are installed by use of flat, prefabricated
boards
which are assembled with the use of jointing material such as joint compounds,
sealing coats, joint coats and/or joint-pointing coats. The prefabricated
elements can be gypsum fiberboards, cement fiberboards, gypsum wallboards
or plaster boards and the like. The flat, prefabricated boards typically
include at
feast one sheet of lining paper, at least one outer layer of which has a
visible
outer face ready to be decorated. Generally, in the construction of interior
walls, flat prefabricated elements, or drywall elements, are fastened to wall
frames by, for example, nails or screws, and the joints taped or plastered
with a
jointing material. The prefabricated elements are assembled together,
optionally with a jointing material and the joints are finished with a sealing
coat,
joint coat and/or joint-pointing coat, so as to obtain an overall visible
outer
surface which is relatively uniform or plane, including in the region of the
joints.
[0003] After the interior assembly work has been completed, the preparation
generally involves covering the overall surface obtained, i.e., the lining of
the flat
prefabricated elements plus the joints, with one or more layers of a paint or
priming or finishing coat. The overall visible outer surface of the flat,
prefabricated boards typically needs to be prepared, before receiving any
surface decoration, such as by application of one or more layers of a film
covering of the paint or lacquer type or a wallpaper. This preparation is
necessitated especially by the shade or colour differences existing between
the
CONFIRMATION COPY
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visible outer surface of the flat prefabricated elements, for example
plasterboards, and the visible outer surface of the joints.
[0004] The preparation operation represents an appreciable additional cost,
for example in a complete process for the construction of a building. And, in
some cases, it is still insufficient for obtaining an overall decorated
surface of
uniform appearance, particularly in view of the physico-mechanical differences
prevailing between the joints and the flat prefabricated elements.
Summary
[0005] Coating formulation for drywall application and systems for drywall
application are provided which simplify the installation of interior walls by
substantially eliminating the need for a final skim coat on the drywall.
[0006] In one embodiment, the invention provides a construction assembly
for interior walls, comprising: (i) skim coated drywall elements comprising
drywall elements having at least one skim coat deposited on the drywall
element, the skim coat being formed from a coating formulation comprising
water, a binder, a filler comprising at least about 60% by weight CaCO3, and a
noncellulosic thickener; and (ii) at least one jointing material jointing the
skim
coated drywall elements to form a substantially plane outer surface.
[0007] In one embodiment, the invention provides an interior construction
system comprising: (i) one or more prefabricated drywall elements; (ii) at
least
one skim coat deposited on the one or more prefabricated drywall elements
from a coating formulation comprising water, a binder, a mineral filler and a
noncellulosic thickener; and (iii) at least one jointing material for
assembling the
one or more prefabricated drywall elements by jointing the drywall elements to
form a substantially plane outer surface, wherein the jointing material, when
dry,
substantially matches the skim coat.
[0008] In one embodiment, the invention provides a method for the
construction of interior walls comprising: (i) assembling skim coated
prefabricated drywall elements, wherein the skim coated prefabricated drywall
elements have a coating layer formed from a coating formulation comprising
water, a binder, a filler comprising at least about 60% by weight CaC03, and a
noncellulosic thickener, and are formed of at least one skim coat deposited on
the prefabricated drywall elements by a coating device; (ii) jointing adjacent
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prefabricated drywall elements with a jointing material to form joints; and
(iii)
drying the jointing material.
[0009] In one embodiment, the invention provides a method for the
construction of interior walls comprising: (i) assembling skim coated
prefabricated drywall elements, wherein the skim coated prefabricated drywall
elements have a coating Layer of at least one skim coat deposited on the
prefabricated elements by a coating device, the skim coat formed from a
coating formulation comprising water, a binder, a mineral filler, and a
noncellulosic thickener; (ii) jointing adjacent prefabricated elements with at
least
one jointing material wherein the jointing material, when dry, substantially
matches the skim coat; and (iii) drying the jointing material.
[0010] In one embodiment, the invention provides a coating formulation for
drywall application comprising water, a binder, a filler comprising at least
about
60% by weight CaC03, and a noncellulosic thickener.
[0011] In one embodiment, the invention provides a skim coated drywall
element having at least one skim coat deposited on the drywall element, the
skim coat being formed from a coating formulation comprising water, a binder,
a
filler comprising at least about 60% by weight CaC03, and a noncellulosic
thickener.
[0012] Specific embodiments are towards the following features:
- the filler comprises at least about 60%, preferably about 75% by weight
CaC03.
- the binder is present in an amount of about 0.5 to about 30%, preferably
to about 15%.
- the binder is a latex binder, preferably an acrylic latex binder.
the coating formulation comprises about 40 to about 70% by weight of
filler, preferably about 45 to about 65% by weight.
- the filler further comprises magnesium carbonate, dolomite, gypsum,
anhydrite, or mixtures thereof.
- the thickener is present in an amount of about 0.05 to about 50% by
weight, preferably about 0.1 to about 5.0% by weight.
- the thickener comprises a copolymer of an acrylic acid and an acrylic
este r.
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- the coating formulation further comprises a dispersant, preferably about
2.0 to about 9.0% by weight of a dispersant,
- the dispersant comprises a sodium poiyacrylate.
- the coating formulation further comprises about 0.1 to about 20% by
weight anti-cracking agent.
- the coating formulation further comprises about 0.1 to about 5% by
weight workability agent.
- the anti-cracking agent is mica.
- the workability agent is clay.
- water is in an amount sufficient to provide a viscosity for the formulation
of about 250 to about 1200 cps, more preferably about 300 to about 450 cps.
- the at least one jointing material and the at least one skim coat form, in
the dry state, a substantially homogeneous outer surface on the substantially
plane outer surface.
- the substantially homogeneous outer surface comprises a level 5 finish.
- at least one of the parameters in the group consisting of coloration,
reflectance factor and surface water absorption is substantially homogeneous
over the substantially plane outer surface.
- the at least one jointing material and the at least one skim coat exhibit
substantially the same surface water absorption when dry.
- the at least one jointing material and the at least one skim coat, each
exhibits when dry, a surface water absorption, as measured by the drop test,
of
at least 45 minutes.
- the at least one jointing material and the at least one skim coat, each
exhibits when dry, a surface water absorption, as measured by the drop test,
of
at least 15 minutes.
- the drywall elements are flat, prefabricated elements.
- the flat, prefabricated elements are gypsum wallboard.
- the drywall elements comprise a core of plaster or gypsum having at
least one sheet of lining paper and a coating layer formed of the at least one
skim coat deposited on the lining paper.
- the skim coat when dry has a thickness of between about 5 and about 60
mil.
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- the skim coat is deposited on the prefabricated drywall element by a
. coating device.
- the skim coat is deposited on the prefabricated drywall element by
spraying during prefabrication of the drywall element.
5 - the drywall elements are gypsum wallboard.
- the jointing material comprises substantially the same solids as the
coating formulation, and wherein the amount of water in the jointing material
is
from about 10% to about 60% less than the amount of water in the coating
formulation.
- the jointing material comprises about 25 to about 45% water, about 40 to
about 70 % of a mineral filler which is the same or different from the mineral
filler of the coating formulation, about 1.0 to about 3.0% anti-cracking
agent,
about 1.0 to about 4.0% clay, about 0.1 to about 1.0% thickener and water
retention agent, about 1.0 to 5.0% talc, about 0.5 to about 20%, preferably to
about 3%, of a binder which is the same or different as the binder of the
coating
formulation, and about 0.1 to about 1.0% starch.
- the thickener and water retention agent in the jointing material comprise
hydroxypropyl methylcellulose.
- the jointing material comprises 50 to 35% of a mineral filler which is the
same or different from the mineral filler of the coating formulation; 1 to 20%
of
an organic binder dispersible in an aqueous phase; 1 to 15% of a silicate-
based
agent; 0.2 to 5% of a hydrophobic agent which is a silicone derivative; 0.05
to
5% of polyvinyl alcohol; and water to make up to 100%.
- the jointing material comprises a binder and wherein the binder in the
coating formulation and the binder in the jointing material is the same.
Detailed Description of the Preferred Embodiments
[0013) The coating formulation and coating and jointing material systems
provided afford improved drywall installation efficiency and improvements in
texture, absorption characteristics, sanding characteristics, processing
characteristics and final performance characteristics. The coated drywall
products produced using the coating formulations, jointing material and
methods disclosed preferably provide a final surface for the drywall that in
some
embodiments substantially equals a level 5 skim-coated finish. The drywall
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finish levels as used herein refer to the Levels of Gypsum Board Finish of GA
274-96: Recommended Levels of Gypsum Board Finish published in 1996. A
level 5 finish is typically recommended for areas where severe lighting
conditions exist and areas that are to receive gloss, semi-gloss, enamel or
non
textured flat paints.
[0014 As used herein, the term "drywall" means any wall structure
especially for interior application, wherein the wall structure may be
prefabricated or not prefabricated material and includes gypsum fiberboards,
cement fiberboards, cement wallboards, plasterboards and the like. Drywall
elements typically are made of a gypsum or plaster core sandwiched or faced in
paper or cardboard and produced like sheets which may be fastened to wall
frames such as with nails or screws. The drywall has a surface usually placed
outwardly in an interior construction such that there is a visible outer
surface or
face ready to be decorated.
[0015 Conventionally, one of the sheets of paper used for making drywall
elements has a dark color which can vary between a gray color and a chestnut
color, since it is composed of cellulose fibers which have not undergone any
particular purifying treatment. Traditionally, this so-called grey paper is
obtained from unbleached chemical pulp and/or from mechanical pulp, and/or
from thermomechanical pulp and/or from semi-chemical pulp. By mechanical
pulp, it is usually meant a pulp obtained entirely by mechanical means from
various raw materials, essentially wood, which can be provided by salvaged
products originating from wood, such as old cardboard boxes, trimmings of
kraft
paper and/or old newspapers. Thermomechanical pulp means a pulp obtained
by thermal treatment followed by a mechanical treatment of the raw material.
By semi-chemical pulp is meant a pulp obtained by eliminating some of the non-
cellulose components from the raw material by means of chemical treatment
and requiring a subsequent mechanical treatment in order to disperse the
fibers.
[0016] The other sheet of a drywall element has a visible face, called a
lining
face, which may be of a color generally lighter than the gray sheet. To obtain
this lighter color, the layer or layers of this face are based on chemical
pulp, if
appropriately bleached, composed of recycled and/or new cellulose fibers,
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and/or on mechanical pulp, if appropriately bleached. By chemical pulp is
meant a pulp obtained by eliminating a very large proportion of the non-
cellulose components from the raw material by chemical treatment, for example,
by cooking in the presence of suitable chemical agents, such as soda or
bisulfites. When this chemical treatment is completed by bleaching, a large
part
of the colored substances is eliminated, as well as the substances which risk
decomposing by ageing and giving unpleasant yellow shades associated with
the presence of, for example, lignin. The coating provided preferably is
applied
to this face of the drywall; however, the coating may be applied to any type
of
paper or outer surface utilized in the manufacture of drywall, including
printed
paper and the like. The jointing material is applied upon installation to
finish the
construction of the interior walls using the coated drywall elements.
[0017] Generally, the coating is applied to all or a portion of the surface of
the drywall either during prefabrication of the drywall elements or boards or
after
installation in the interior of a structure. The coating has a composition
compatible with the jointing material and is applied as a skim coat or film
coat of
relatively low thickness on the visible surface of the drywall. One or more
coats
may be applied. The coating preferably provides a substantially homogeneous
appearance to the drywall even after the joints are prepared as is known in
the
art. The characteristics of the coating are such that the coating and other
materials, especially jointing materials, utilized in the installation of
drywall
compatibly provide a substantially homogeneous appearance. The drywall
installation is simplified since one or more layers of primer or paint or
finishing
coats are not required to complete the preparation of the wall for decoration.
Specifically, in preferred embodiments, when the coating is applied to
drywall,
an additional skim coat or finishing coat is not required to obtain a level 5
finish.
[0018] Any commercially available jointing material may be used to complete
the construction of the interior surface of the interior structure installed
with
coated drywall. In one embodiment, the jointing materials described herein are
used to complete the construction of the interior surface of the interior
structure
installed with coated drywall. The jointing material may be used for any
purpose for which such materials are known such as jointing compounds,
sealing coats, joint coats or joint-pointing coats.
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[0019] After the coating and jointing material system has been applied to
drywall, the jointing material jointing the skim coated drywall elements and
the
skim coated drywall elements form a substantially plane outer surface
comprising a surface of the jointing material and a surface of the skim coated
drywall elements. This surface may then be decorated as is known in the art by
application of a paint or wallpaper covering.
The Coating Formulation
[0020] The coating provides a smoothing of the texture of the drywall such
that the fibers typically seen under primer or paint after installation of the
drywall
are substantially covered. Moreover, the coating changes the characteristics
of
the drywall to provide a surface with an absorbance closer to the absorbance
of
the jointing material surface when dry, which surface is thus visually
substantially uniform. The coating also provides a durable surface such that
the
sanding on the jointing material does not easily remove or damage the coating
surface. Thus, the coating preferably provides a durable surface with a
sufficiently smooth texture and absorbance to be substantially compatible with
the jointing material.
[0021] The coating typically is a drying type coating and the coating
formulation comprises water, mineral filler, binder and thickener. The coating
preferably also includes a dispersant. The water is provided in an amount
effective to provide a suitable viscosity to the coating formulation such that
the
coating formulation may be applied by any desirable means to the drywall
material.
[0022] The mineral filler may be any of the fillers known in the art for use
in
surface coating compositions or a combination thereof. Preferably, the mineral
filler is of light color, preferably white with a grain size or particle size
distribution
wherein the mean diameter D50 is between about 5 and about 35 pm, as
determined by light scattering techniques. Too large a grain size of the
filler
gives rise to overall surface defects, such as a reflection of light radiation
on the
surface of the coat which is different from that on the surface of the
drywall,
bringing about differences in tone and brightness of the shade. Too large a
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grain size also gives rise to differences in physical appearance which are
associated with the differences in roughness between the board and the
coating.
[0023] Preferably, the mineral filler comprises more than about 60% calcium
carbonate, more preferably more than about 75%, and most preferably greater
than about 90% calcium carbonate. Other fillers may also be used in lesser
amounts, such as magnesium carbonate, dolomite, gypsum, anhydrite and the
like. By way of example, calcium carbonate filler such as Pulpro 15 from OMYA
may be used. The mineral filler represents about 40 to about 70% of the total
weight of the coating formulation. Preferably, the mineral filler represents
about
45 to about 65% of the total weight of the coating formulation.
[0024] The coating formulation preferably further comprises a dispersant.
The dispersant provides cohesion for the formulation, holding the components
of the formulation in suspension even where the viscosity of the coating
formulation is relatively low for a coating material. The dispersant may
include
any dispersant or mixtures thereof which function as desired, preferably any
polyacrylate or polymeric acrylic salt or mixtures thereof, more preferably a
salt
of polyacrylate such as a sodium polyacrylate. By way of example, Acumer~
9300 or Acumer~ 9400 produced by Rohm and Haas Company may be used.
[0025] The dispersant preferably represents about 0.5 to about 15.0% of the
total weight of the coating formulation. More preferably, the dispersant
represents about 1.0 to about 5.0% of the total weight of the coating
formulation.
[0026] The coating formulation also comprises an organic binder, preferably
dispersible in aqueous phase, preferably in a proportion of between about 0.5
and about 30%, preferably about 0.5 and about 15.0%, and more preferably
between about 1.0 and about 4.0%, of the total weight of the coating
formulation. The binder preferably imparts sufficient flexibility to the coat
to
withstand mechanical stresses, and has both an adhesive capacity for obtaining
a good bond on the overall surface and good resistance to attacks of
ultraviolet
tight. In addition, the binder typically will function to harden the surface
of the
coating after application.
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[0027] The binder in the coating formulation preferably will be a Latex
binder,
or a mixture of such binders. In a preferred embodiment, the binder is an
acrylic latex binder. By way of example, an acrylic latex such as AC-630 from
Rohm and Haas Company may be used.
5 [0028] The coating formulation further comprises a thickening agent which
provides an increase in viscosity and functions to aid in holding the
components
of the coating formulation in suspension. The thickening agent preferably is
primarily a noncellulosic thickener or a mixture of noncellulosic thickeners.
In
some embodiments, other thickeners known in the art such as cellulosic
10 thickeners may be included in the formulation as part of a mixture of
thickening
agents. By way of example, noncellulosic thickeners generally identified as
alkali soluble emulsions or hydrophobically modified alkali soluble emulsions
may be used. More preferably, the thickener is a polymeric nonceliulosic
thickener such as a polyacrylate, especially a copolymer of an acrylic acid
and
an acrylic ester. In a most preferred embodiment, the thickener is a copolymer
of acrylate and methacrylic acid. By way of example, ASE-60, a polyacrylate of
the alkali soluble emulsion category, or TT-615, a polyacrylate of the
hydrophobically modified alkali soluble emulsion category, both from Rohm and
Haas Company, may be used.
[0029] The thickener generally is used in a proportion of about 0.05 to about
50%, and preferably of about ~ 0.1 to about 5.0%, of the total weight of the
coating formulation.
[0030] In addition to the water, mineral filter, dispersant, binder and
thickener, at least one workability agent may be included in the composition
of
the coating formulation, especially a clay, in the proportion of about 0.1 to
about
5.0%, and preferably of about 1.0 to about 2.0%, of the total weight of the
coating formulation. The workability agent is preferably one or more silicate
derivatives and, more preferably, a clay of the attapulgite type, such as
M3214
from Engelhard.
[0031] An anti-cracking material may also be desirable in the coating
formulations. Such materials are known in the art and may include materials
such as mica. By way of example, MW 200 from Oglebay Norton may be used.
The anti-cracking agent may represent about 0.1 to about 20% of the total
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weight of the coating formulation. Preferably, the anti-cracking agent will
represent about 1.0 to about 2.0% of the total weight of the coating
formulation.
[0032] Other components, such as biocides, anti-foaming agents,
preservatives, water treatment agents and pigments may also be incorporated
in the composition of the coating formulation in. the conventional way. For
example, a water treatment agent may be needed to adjust the pH of the
coating formulation depending on the water used or the ultimate use of the
formulation. Such water treatment agent may be bicarbonate, which may be
used in certain embodiments to ensure the pH is above about 8. Preservatives
are known in the art and include such materials as hexahydro-1,3,5-tris(2
hydroxyethyl)-s-triazine. By way of example, Troysan 165 from Troy
Corporation may be used. The additional components such as biocides, anti
foaming agents, preservatives, water treatment agents and pigments are
typically used in relatively minor amounts, generally less than about 1.0% of
the
of the total weight of the coating formulation.
[0033] The coating formulation, by way of example, may be prepared by
combining a first fraction of water with the binder and dispersant and mixing
the
combination. If a water treatment agent such as bicarbonate is to be added,
such agent may be included in the first mixing step. The viscosity of the
formulation should be kept as high as possible for as long as possible in
order
to effectively optimize the mixing process.
[0034] After sufficiently mixing the binder and dispersant with the first
fraction of water, the mineral filler such as calcium carbonate is added,
followed
by the mica and the clay. If a preservative is to be used, the preservative
may
be added in this step, along with other optional components known to those of
skill in the art. The coating formulation is further mixed prior to addition
of the
thickener. The remaining water preferably is added last; however, if the
coating
formulation mixture after addition of the mineral filler has a high viscosity,
e.g.,
the coating formulation mixture is too thick, some water may be added prior to
adding the thickener. Any water remaining may be added after addition of the
thickener.
[0035] Typically, the viscosity of the coating formulation will be about 250
to
about 1200 cps, more preferably about 300 to about 450 cps, as determined by
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a Brookfield viscometer at room temperature. By way of example, the viscosity
may be measured for the coating formulation using T-bar spindle number S91
with 100 rpm. The viscosity of a jointing material may be measured, for
example, using T-bar spindle number S94 with 2.5 rpm. The viscosity may be
adjusted by any means known in the art to provide a coating formulation
suitable for the desired application.
[0036] The coating formulation preferably is used on prefabricated drywall
elements, preferably flat prefabricated elements such as gypsum fiberboards,
cement fiberboards, gypsum wallboards, plaster boards and the like.
[0037] The coating formulation preferably is applied as a skim coat, or film
coat of relatively low thickness on the outer surface of drywall made from
prefabricated elements. The coat may be applied before or after the drywall is
sent through a drier. Preferably, however, the coat will be applied prior to
the
drier so that the coat may be dried as the core is dried.
[0038] The skim coat may be applied, by way of example, in the plant by, for
instance, roll coating, curtain coating, vacuum coating, spraying or the like
via a
coating device, on the prefabricated element so that the skim-coated
prefabricated element is delivered to the assembly site already with a skim
coat
on it. Alternatively, the coating formulation may be supplied to the user for
application to the drywall or boards after the drywall or boards are placed
into
position during interior construction. The skim coat from the coating
formulation
provides a substantially uniform or plane surface with the joint compound used
to install the drywall or boards upon which the skim coat is placed.
[0039] The coating formulation preferably is applied using a spraying device,
which is operated under standard conditions for coating a product onto a
board.
The dimensions, rotating speed, feeding, temperature, and any other operating
conditions are within the skill of a person of ordinary skill in the art. In a
preferred embodiment, the coating is applied in a manufacturing line for
boards.
Said manufacturing line may comprise: (i) a conveyor for moving gypsum
boards in a line; (ii) a spray arm having a pivot at one end thereof for
supporting
the spray arm in a pivotable manner; (iii) a base frame mounted adjacent the
conveyor; (iv) a support for the pivot mounted on the base frame so that the
spray arm can be pivoted from an operative position wherein the spray arm
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extends over the conveyor to an inoperative position; (v) a plurality of spray
nozzles arranged on the spray arm for spraying a coating on gypsum boards on
the conveyor; and (vi) a pump system on the frame to deliver the coating to
the
plurality of spray nozzles.
[0040] By way of example, drywall material such as gypsum board is
prepared according to standard practices, including depositing a calcined
gypsum slurry between two sheets. Methods of producing gypsum board,
including coated gypsum board, are described for example in WO-A-02058902,
incorporated herein by reference in its entirety. The coating formulation may
be
applied after the gypsum sets but prior to the gypsum being completely dry.
Thereafter, the gypsum wallboard is dried in conventional driers which dry
both
the coating and the gypsum. It has been discovered that the coating is
sufficiently permeable to allow moisture in the gypsum to be satisfactorily
eliminated through the paper and the coating thereon. An impermeable
substance applied to the paper cover sheet of the gypsum wallboard when the
core is still wet may cause the paper sheet to separate or delaminate from the
core as moisture is driven off in the drier. The coating formulation provided,
however, may be advantageously applied during manufacture of the drywall
without substantially negatively affecting the drying characteristics of the
core
material or time required for drying the core material.
[0041] The final thickness of the coat from the coating formulation, as
determined when dry, is generally between about 5 and about 60 mil, preferably
between about 10 and about 15 mil.
[0042] In one embodiment, the jointing material also comprises a system
including water, binder, thickener, dispersant, and filler, particularly
CaC03, in
amounts resulting in a material with properties suitable for a jointing
material
and which provides a substantially similar surface to the coating as to
texture
and absorbance, enabling the coating and jointing material when dry to
preferably provide a level 5 finish without application of a skim or final
coat.
Thus, a final skim coat may be eliminated from the preparation of the wall,
saving time and money when constructing interior walls. Preferably, the
jointing
material used is as disclosed below. In other preferred embodiments, the
jointing material may be as disclosed in U.S. Patent Application Publication
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Nos. 200310153651 and 2003/0084633, both of which are hereby incorporated
by reference in their entireties.
[0043] The selection of the jointing material used with the coating may be
made such that the jointing material, when dry, substantially matches the
coating on the drywall element or board. Since the composition of the jointing
material and the coat are adapted to match each other, the jointing material
and
the coat form, both in a dry state, a substantially homogeneous outer surface
having over substantially all its surface at least one of the parameters
comprised in the group consisting of coloration, reflectance factor and
surface
water absorption which ~is substantially homogeneous over the surface. For
instance, the at least one of the parameters differs by no more than 10%,
preferably no more than 5%, at different parts of the overall surface, so that
at
least 90°l°, preferably at least 95%, homogeneity is achieved.
In other words,
as an example, when the jointing material and the prefabricated elements are
dry, the at least one of the parameters of the visible surface of the jointing
material can differ by not more than 10%, preferably not more than 5%, from
the
corresponding parameter of the visible surface of the prefabricated elements.
Alternatively, each parameter may be adjusted so that each parameter is at
least a given value.
[0044] The characteristics of the surfaces may be compared by the following
tests: (A) Color. The color deviations delta E* are measured on a spectro-
colorimeter according to the standard DIN 6174 at an angle of 8°,
illuminant
D65 as a bright specular, included in the system L*, a*, b*, in which L* is
the
luminance, a* represents the transition from green to red, and b* represents
the
transition from blue to yellow. A point E* in this system, the said point
being a
function of L*, a*, b*, defines the colorimetry of a sample and the deviation
is
measured in relation to a reference point. In general terms, a color deviation
beyond 2 becomes discernible to the naked eye. (B) Degree of whiteness or
reflectance factor R obtained according to standard NFQ 03038 with a
wavelength of 457 nm. This degree represents the a reflected radiation of the
body in question and that of a perfect diffuser under the same conditions.
Preferably the whiteness is between 70 and 80%, most preferably between 72
and 76%. (C) Surface water absorption determined by the drop test. A drop of
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distilled water of a volume of approximately 0.05 cm3 at 23°C. is
deposited on
the surface (conditioned atmosphere). It is important that the drop be
deposited
and not allowed to fall from a variable height which consequently would crush
it
to a greater or lesser extent, thus falsifying the result. The duration in
minutes
5 (time for the glossy surface to disappear) represents the surface absorption
of
the tested area.
[0045] According to a preferred embodiment, the jointing material and the
coating exhibit substantially the same surface water absorption or
absorbability.
In one embodiment, the surface water absorption, as measured by the drop
10 test, is at least 15 minutes for both the joint and the board, preferably
at least 45
minutes and more preferably at least 60 minutes. Preferably, the jointing
material and the coating exhibit also substantially the same coloration andlor
reflectance factor. In another embodiment, each of the joint and the board
exhibits a surface water absorption, as measured by the drop test, of at least
45
15 minutes for each of the joint and the board, preferably at least 60
minutes,
where values measured on the joint and on the board may differ by more than
10%.
[0046] A suitable jointing material may be selected according to the
preceding description and/or may be selected from the embodiments of jointing
material set forth below.
Jointing Material - Preferred Embodiment No. 1
[0047] In one embodiment, the jointing material preferably used with the
coating described is derived from the components of the coating formulation.
Thus, the jointing material in this embodiment comprises water, mineral
filler,
binder, thickener, and optionally, dispersant. This jointing material provides
a
substantially similar surface as the coating as to texture and absorbance,
enabling the coating and jointing material when dry to preferably provide a
level
5 finish without application of a skim or final coat. Thus, a final skim coat
may
be eliminated from the preparation of the wall, saving time and money when
constructing interior walls.
[0048] The jointing material of this embodiment preferably is formulated to
comprise substantially the same components as the coating formulation, with
variations in the amounts of each component according to the desired
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16
characteristics. Since the jointing material and the coating formulation
comprise
substantially the same components, the properties of the coating and jointing
material are compatible and preferably provide the desired substantially
homogeneous surface for the drywall construction.
[0049) Preferably, the jointing material of this embodiment will comprise
about 40 to about 70% mineral filler, wherein the mineral filler is greater
than
about 60% calcium carbonate, about 0.5 to about 30%, preferably to about
15%, binder, about 0.05 to about 50% noncellulosic thickener, optionally about
0.5 to about 15.0% dispersant, about 0.1 to about 5.0% workability agent and
about 0.1 to about 20% anti-cracking agent, all by weight. Other components
may also be present in minor amounts as discussed for the coating formulation.
Water is provided in an amount to make up 100% of the jointing material.
(0050) Water is present in the jointing material in an amount effective to
provide a suitable viscosity to the jointing material such that the jointing
material
may be applied by any desirable means to effect assembly of the drywall
elements. Since the jointing material typically has a higher viscosity than a
coating composition, the jointing material will preferably include less water
than
the coating formulation. The coating formulation may, in a preferred
embodiment, be a diluted version of the jointing material. For example,
compared to the jointing material such as the joint-pointing coat, the
coating,
when applied (for example, when the coating is applied to the prefabricated
elements, or when the skim coated prefabricated elements are assembled), will
comprise more water than initially present in the jointing material. It will
thus
generally comprise additional water, e.g., about 10 to 60%, preferably about
15
to 40%, more preferably about 25°I°, more water than initially
present in the
jointing material. By "water initially present in the jointing material", it
means the
amount of water present in the jointing material when the jointing material is
applied to the skim coated prefabricated elements, before the jointing
material is
in a dry state.
(0051) In a most preferred embodiment, the jointing material and the coating
formulation preferably have substantially the same solids formulation, the
coat
when applied having a solids content lower than the jointing material when
applied. Thus, in this preferred embodiment, substantially the same filler,
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17
binder, thickener and other optional components of the coating formulation are
present in the jointing material.
Jointing Material - Preferred Embodiment No. 2
[0052] In another embodiment, a jointing material comprising water, mineral
filler, binder, thickeners and rheologic agents, and an anti-cracking agent is
provided.
[0053] The filler may be any of the fillers known for jointing materials such
as
such as calcium carbonate, magnesium carbonate, dolomite, gypsum, anhydrite
and the like, including combinations thereof. Preferably, the filler will
comprise
at least about 60% calcium carbonate. The filler, by way of example, may by
Pulpro 15.
[0054] The binder may be an acrylic polymer typically used as a binder. One
example of a suitable binder is AC630 from Rohm and Haas Company.
[0055] The thickeners and rheologic agents may be selected from one or
more silicate compounds or from starches. Particularly, one or more clays,
such as attapulgite, may be used. By way of example, Engelhard M8214 or
Attagel 30 may be used. Another silicate, talc, may also preferably be used as
a rheologic agent, preferably in conjunction with one or more clay components.
For example, Luzenac TC100 may be used. Starch may also preferably be
used as an additional thickener and rheologic agent. As an example, Starpol
136, 767 or 600, amylopectin hydrogen phosphate 2-hydroxypropyl ether, may
be used. In a most preferred embodiment, the jointing material includes each
of a clay, talc and a starch as rheologic and thickening agents.
[0056] Preferably, a thickener and water retention agent is also used, such
as a cellulose compound or mixture of cellulose compounds. Suitable cellulose
compounds include hydroxypropyl methylcellulose compounds such as Dow
Chemical Methocel 240S, Methocel 40320 or Samsung PMC40US.
[0057] The anti-cracking agent may be any agent known for this purpose.
Preferably, the anti-cracking agent is mica such as Georgia Mineral SG75 or
Oglebay Norton MW200.
[0058] Preferably, the jointing material comprises:
water- about 25 to about 45%
filler- about 40 to about 70
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anti-cracking agent - about 1.0 to about 3.0%
clay - about 1.0 to about 4.0%
thickener and water retention agent - about 0.1 to about 1.0%
talc - about 1.0 to 5.0%
binder - about 0.5 to about 20%,
preferably about 0.5 to about 3.0%
starch - about 0.1 to about 1.0
Jointing Material - Preferred Embodiment No. 3
[0059] In another embodiment, the jointing material described in U.S. Patent
Application Publication No. 2003/0153651, incorporated herein by reference in
its entirety, may be employed as the jointing material.
[0060] The jointing material or plaster described in the '651 publication is
directed to a composition of
- 50 to 85% of a mineral filler;
- 1 to 20% of an organic binder dispersible in an aqueous phase;
- 1 to 15% of a silicate-based agent;
0.2 to 5% of a hydrophobic agent which is a silicone derivative;
- 0.05 to 5% of polyvinyl alcohol; and
- water to make up to 100%.
[0061] As mineral filler, any mineral filler commonly employed for the
manufacture of a jointing compound or plaster may be used. In general, the
mineral filler will be light in color, preferably white, and the mean diameter
d50 of
which is in general between 5 and 35 microns as determined by light scattering
techniques, so that the jointing material after drying gives a smooth finish
corresponding to that of the facing of the board.
[0062] As examples of mineral filler, mention may be made of calcium
carbonate, anhydrous or dihydrated calcium sulphate, magnesium carbonate,
dolomite, silicas, silicates, aluminates and other such materials.
[0063] Preferably, calcium carbonate CaC03 is used.
[0064] The mineral filler preferably represents between 50 and 70% of the
total weight of the jointing material.
[0065] According to one embodiment, the binder/silicate-based agent weight
ratio is between 0.5 and 2.
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[0066] According to one embodiment, the binder/hydrophobic agent weight
ratio is between 1.5 and 10.
[0067] According to an advantageous embodiment, the mineral filler
furthermore includes perlite, preferably expanded and even more preferably
hydrophobic perlite. The amount of perlite is then generally between 2 and 5%.
[0068] As organic binder dispersible in an aqueous phase, mention may be
made of polyvinyl acetate homopolymers (plasticized or unplasticized),
ethylene/vinyl acetate copolymers (plasticized or unplasticized EVAs),
ethylene/vinyl versatate copolymers, vinyl acetate/vinyl versatate copolymers,
polyacrylics, vinyl acetate/acrylic copolymers, styrene/acrylic copolymers,
styrene/butadiene copolymers, vinyl acetate/vinyl versatate/vinyl maleate
terpolymers, vinyl acetate/vinyl versatate/acrylic terpolymers, acrylic
terpolymers, acrylic polymers or homopolymers, and blends thereof.
[0069] The proportion of organic binder is preferably between 2 and 12% of
the total weight of the jointing material.
[0070] The silicate-based agent (different from the mineral filler) preferably
comprises talc and/or mica andlor a clay. Preferably, a mixture of talc and
mica
is used.
[0071] The proportion of silicate-based agent is preferably between 3 and
10% of the total weight of the jointing material.
[0072] The hydrophobic agent is a silicone derivative. As silicone
derivatives, mention may be made of siliconates, silanes, hydrogenated
silicone
oils, silicone emulsions, aminosilicone emulsions, alkylsiloxane resins, such
as
hydrogenomethyl-polysiloxane and aminated polydimethyl-siloxane, and
mixtures thereof.
[0073] Preferably, a resin of the aminated polydimethyl-siloxane type is used
as silicone derivative.
[0074] The proportion of silicone derivative is preferably between 0.5 and 3%
of the total weight of the jointing material.
[0075] Advantageously, the proportion of silicone derivative is chosen so as
to allow a joint to be produced which has the same surface properties as those
of the facing paper. These surface properties are decolouration or colouration
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owing to the efFect of the natural color, reflectance and surface water
absorption. These properties are described above.
[0076] The proportion of polyvinyl alcohol is preferably between 0.05 and 1
of the total weight of the jointing material.
5 [0077] According to an advantageous embodiment, the jointing material
furthermore includes starch and/or a starch derivative.
[0078] The proportion of starch and/or starch derivative is in general
between 0.05 and 5%, preferably between 0.1 and 1 %, of the total weight of
the
jointing material.
10 [0079] The jointing material may be prepared by mixing its constituents in
any order.
[0080] Of course, provided that the proportions assigned to each of the
essential constituents are respected, it is possible to introduce into the
jointing
material according to the invention, as secondary ingredients, additives
15 normally used to facilitate the processing of the other constituents or for
conferring additional particular properties on the jointing material. By way
of
examples of such additives, mention may be made of water-retaining agents or
thickeners, slip agents, dispersants, antigels, pigments, biocides and
antifoams.
These additives are described, for example, in the application WO-A-9702395,
20 incorporated herein by reference.
[0081] Embodiments of the invention will now be more fully explained by the
following examples. However, the scope of the invention is not intended to be
limited to these examples.
Example 1
[0082] A coating formulation according to an embodiment as set forth in
Table 1 was prepared as follows:
[0083] To the first part of the water, bicarbonate, binder, and dispersant
were
added and mixed. The calcium carbonate was then added and mixed, followed
by the mica, clay and preservative, which were also mixed. The thickener then
was added and mixed into the formulation. The remaining water was added
after the thickener was mixed into the formulation.
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TABLE 1
Material Name Pounds Dry Solids
Water 294.68 21.8
Bicarbonate 0.42 100 0.03
AC-630 resin, binder (acrylic latex)25.79 50 1.91
Acumer 9400, dispersant (sodium 27.09 42.5 2.00
polyacrylate)
Calcium carbonate 771.28 100 57.06
Mica 26.43 100 1.96
Clay 19.32 100 1.43
ASE-60, thickener (copolymer acrylate1.62 28 0.12
and
methacrylic acid)
Water 185.00 13.6
Total Pounds 1351.63
Weight solids (%) 61.40
% Dispersant - total formulation 2.00
thickener - total formulation 0.12
binder - total formulation 1.91
Example 2
[0084] A coating formulation according to Table 2 was prepared according to
the procedures of Example 1.
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TABLE 2
Material Name Pounds Dry Solids
Water 297.56 21.80
Bicarbonate 0.43 100 0.03
AC-630 resin, binder (acrylic latex)26.25 50 1.92
Acumer 9300, dispersant (sodium 27.38 45 2.00
polyacrylate)
Calcium carbonate 784.89 100 57.51
Mica 26.90 100 1.97
Clay 19.66 100 1.44
TT-615, thickener (copolymer acrylate1.64 30 0.12
and
methacrylic acid)
Water 180.00 13.19
Total Pounds 1364.71
Weight solids (%} 61.90
Dispersant - total formulation 2.00
thickener - total formulation 0.12
% binder - total formulation 1.92
Example 3
[0085] A jointing material according to preferred embodiment no. 2 was
prepared with the following composition:
water - 33.0%
limestone (CaC03) - 57.0%
mica - 2.0%
clay attapulgite - 2.5%
hydroxypropyl methylcellulose - 0.5%
talc - 3.0%
acrylic polymer- 1.5%
starch - 0.5%
[0086] While the preferred embodiments of the invention have been
disclosed in detail, it will be apparent to one skilled in the art that
various
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changes and modifications can be made without departing from the spirit and
scope .thereof.
