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Patented Oct. \22, 1946’
2,409,629
UNITED STATES PATENT OFFICE
MANUFACTURE OF coa'ran BOARD
Clark 0. Heritage, Cloquet, Minn.,a'ssignor to
Wood Conversion Company, Cloquet, Minn., a
corporation of Delaware
No Drawing. Application September 9, 1939,
‘Serial No. 294,213 ’
1
'
6 Claims._ (Cl. 92—40)
The present invention relates generally to coat
ing compositions and to the use thereof. In par
ticular it relates to the‘manufacture of arti?cial
board with a coating thereon. It also relates par
>
2
It is also an object of the invention to provide
a coating composition for wallboard, which may
be used in process of manufacture or after manu
facture of the ?nished board per se, which main
ticularly to such a coating applied during the
tains its applied position and its covering power
manufacture of the board.
for ?bers.
It is a particular object of the invention to
Heretofore, considerable di?iculty has been en
countered in attempts to produce coats on inher
provide an aqueous coating composition so that
ently rough surfaced ?ber boards, of vegetable
it may be used compatibly with wet stock in the
?ber, of natural mineral ?ber, or ‘of synthetic 10 manufacture of board.
mineral ?ber. To secure the desired color and
It is also an object of the invention to use a
permanence, it is necessary to cover entirely all
coating composition which will withstand a high
of the exposed surface ?bers. This may be done
temperature such as to permit it to be dried
by loading the surfaces to ?ll all the interstices
simultaneously with a wet sheet carrying it in
and to cover all the ?bers. However, this is waste 15 forming a board, and which is highly bene?ted
by the action of heat on such drying.
ful of coating material, and in addition it hides
the texture of the uncoated board, which texture
It is another object of the ‘invention to use a
is often desired, not in the natural ?ber color
permanent white pigment to form a coated board
but in the same or other colors which may be of
of high light re?ectance.
more varied and permanent‘ character.
It is'also an objectiof ‘the invention to provide
20
a coating composition and a coated board which
Heretofore, formed ?ber boards, that is dry
boards after formation, have been treated with ’ is washable with soap and water; which is re
coating compositions in attempts to give new
surface colors. There, are disadvantages in such
sistant to scuff; which may be easily painted
later with oil-paints without high absorption of
practices. The composition either soaks in, or 25 the oil; which resists absorption of water; which
if it ‘does not take well, the fibers are not wholly
will not spot with water, and may be later painted
covered. A fractional area of exposed vegetable
?ber readily affects the appearance and perma
nence of the color in spite of the fact that the
added color itself may be permanent in char
acter. This is due to a change in color in vege
table ?ber when it is exposed to light. Also, on
with a water‘ paint; which will not cause warping
of the board; which is cleanable with wall paper
cleaners; which lacks odor; and which has gen
erally desirable characteristics to provide and to
maintain pigmented colored ‘walls or ceilings in
a home, o?ice, hall or like quarters.
»
drying liquid coating compositions applied to dry
Various other and ancillary objects and advan
board, the board may be pulled into a warp by
tages of the invention will become apparent from
"stresses produced in the coat, if there is no vre 35 the following description and explanation of the
straint in drying. Particularly, boards which are
invention.
made water-resistant when dry, do not take well
The boards for which the coating compositions
are most desirable are these-called insulating
any aqueous composition applied to surface,
unless it is copiously applied. A copious applica
wall boards. For their practical uses, such boards
40 are required to be water-proofed or water-resist
' tion increases the warping tendency.
The present invention provides a composition
which may be applied to boards while they are
ant. This is commonly done in process of manu
facture by using an emulsion of a water-proo?ng
agent such as a fat, oil, wax or metallic soap, ’
wet in process of manufacture, which takes well
in both light and heavy usages to assure covering
which will e?ect the result desired. Where wax
45
all the exposed ?bers, and which may be used
is used as an emulsion, the emulsion is precipi
in small quantity to leave the texture and coat
tated, as with alum, and the precipitated'par
the ?bers, or in higher quantity to coat the ?bers
ticles on the ?ber do not attain their ultimate
and partially ?ll the interstices, thus exhibiting
function until the board is dry. Thus, a so—
texture, or in still higher quantity which may 50 treated board when dry is resistant to an aqueous
coating composition. Yet the same board in
hide the ?bers and the interstices to form a
smooth coat, practically hiding texture.
process, while moist and lbefore drying, is not re
It is an object of the invention to provide a
sistant to such a composition. This is a very
pigmented surface appearance on board with
important distinction where low usage of coating
complete coverage. of ?ber surface by the pig w material is desired. Under such conditions of
ment, and with varying e?ects in appearance of
low usage, the board surface (viewed microscopi
texture due to variations in usage.
cally) presents a brush-heap‘appearance, with
2,409,029
3
individual ?bers raised high from the body, and
Example 2
with deep recesses de?ned by other matted ?bers
of the brush-heap appearance. A‘ thin coat of
material must adhere to the entire surface of the
?bers. Dry water-resistant ?bers tend to repel
the composition leaving un'coated portions of
?bers, and forcing the composition to span the
inter-?ber spaces. No perfect continuous color
results, because of the uncoated portions of ?bers
showing through. Such a board is not stable in
color because of the photochemical and atmos
pherically induced change of color in the exposed
?ber. To avoid uncoated spots on ?bers, high
usage is required, which also has a ?lling action
Parts by weight
“Aquaplex" No. A-90 ____________________ __ 24
Water _____ __
39
Pigment (such as titanium dioxide) _____ _'___ 36
Example 3
' ,
Parts by weight
“Aquaplex" No. A-90 ____ ___ _____________ _.. 34
Water _
34
Calcium carbonate ___________ ____________ __ 32
The above composition of Example 1 is pre
ferred. It contains about 45% water, and the
on the pores or interstices.
15 proportions of solids to water are made such as
Accordingly, it is most important to provide a
coating composition which is susceptible to use
to render the composition suitable for the process
of application, which is speci?cally the use of a
roll pressing on wet board (60% water) behind
which roll there is a pool of the composition.
for entirely covering all the exposed ?bers at very
low usage.
The composition requires a. pigment to give the 20
In the preferred composition of Example 1
color, and a vehicle therefor containing binder
there are about 11 parts of binder to 44 parts of
for binding pigment particles to each other and '
pigment, which makes a coating residue of about -
to the ?ber. Mineral pigments are preferred, but
20% binder. These proportions are by no means
any pigment which withstands the action of heat
limitations, because the amount of water depends
where it is encountered in the procedure chosen, 25 in part upon the workability of the process, and
as for example, where the wet coated board is
the proportion of binder to pigment depends in
oven dried.
part upon the kind and form of pigment. The
The vehicle is essentially aqueous to assure a
pigment however, should predominate, inasmuch
loss of vehicle substance in drying the coating,
as the intended coat is one of particles cemented
to assure mutual wetting of wet ?bers and the 30 to each other and to ?ber, rather than a ?lm of
composition, to avoid vapors of organic solvent
vehicle in which the pigment is dispersed.
material, and to lessen cost.
With reference to the above pneferred ex
The binder for the present invention is one
ample, it is to be noted that the “Aquaplex"
which may be dispersed in an aqueous vehicle,
emulsion is diluted about 100% with water, and
and which is set as a, binder at normal tempera 35 the pigment is ultimately dispersed in the diluted
ture when dry, being either thermo-plastic or
emulsion. The binder and the pigment are each
heat-hardening. In other words, resins which
largely suspended independently of each other in
set on heating, as well as thermoplastic materials,
the aqueous vehicle.
are included. The binder may be water-soluble,
The composition has high adherence and uni
water-emulsi?able, or otherwise dispersible- in 40 form spreading power over wet ?bers, with or
water. It may be a synthetic resin not in ?nal
without a latent water-proo?ng compound, such
reacted form, a condensation product capable of
as paraf?n precipitated from emulsion in the ?ber
further reaction with itself or some other ingredi
slurry which forms the board. In high usage it
ent, or it may be a mixture of materials which
also has adherent power to dried ?bers with or
react after application to the board. For exam 45 without the water-proo?ng treatment. But in
ple, it may be monomethylol urea, or dimethylol
low usage it does not adhere uniformly to the
,urea, or some water-soluble mixture or product
’ of urea and formaldehyde. It may be an emul
dried water-proofed board.
By applying the preferred composition to moist
sion of phenol-aldehyde resin, or the alkyd resins
or wet board before the ?rst drying, light to
which are thermo-setting with increasing tem 50 heavy usage may be employed with variable re
perature. Certain polymerized esters of alcohols
sults as desired. By drying the coating and the
and acrylic acid are water-soluble before the
board together, the tensions resulting are such
water is driven off, and insoluble thereafter, and
that the coating, even though it is thick, does not
hence, although thermoplastic, are suitable for
pull the board into a warp.
use.
The thermoplastic binders are not so uni
55
versally useful as the heat-setting resins, since
the former call for too careful action at the ele
vated temperatures where the binder is soft.
Preferably, the heat-setting products are used
which harden at high temperatures.
60
Emulsions of resins which are heat-setting are
available on the market. One such is termed
The coating may be applied by brushing, by
spraying, by roll transfer, by roll and pool, or by
doctor blade, according to desire. The viscosity of
the coating is pertinent to the method of applica
tion, and it may be controlled by varying the wa
ter content, or the binder content, or both, or the
kind or form of the pigment. For example, a
composition which is suitable for application by
“Aquaplex” No. A-90, manufactured by Resinous
a pool behind a roll, is suitable for application
Products 8: Chemical Company, Inc., of Philadel
by spraying, but every composition which is suit
phia, Pennsylvania, and it is a glycerol-phthalate 85 able for spray-coating is not suitable for the roll
carried in aqueous suspension of 40% solids. It
and pool method.
sets on losing water, as by drying, to an irreversi
The effect of viscosity is exempli?ed by refer
ble form. At elevated temperature setting prop
ence
to the use of a pool behind a roll. In such
erty is enhanced.
use the moist mat approaches downwardly the
70 nip of two rolls and passes through with the
Example 1
formation of a pool of coating composition on the
Parts by weight
mat behind the top roll. The moisture in the mat
“Aquaplex” No. A-90 ___________________ __ 28
and ?bers assures that the ?bers are wettable
Water ___
by the composition, and the covering pool assures
28
Pigment (such as titanium dioxide) _______ __ 44
75 perfect contact.
2,409,029
.
The pressure of the upper roll is controllable in
the degree-with which it compresses the mat.
Thus it effects a forcing of the composition well
into the surface, controls the amount which is
squeezed back into the pool, and hence controls
the amount left on the mat. The ?bers at the
top spring back and carry with them a perfect
coat of pigment. In such springing back, the
pores tend to suck in any free liquid. Where a
6 ‘ _
(thick-boiled as in laundering) may be used as
an under-coat, ?lling the pores and sizing the
?bers, and while the board is still wet with such
starch solution, the pigmented aqueous composi
tion may be applied, as if no sizing were present.
In the speci?cation and accompanying claims
where reference is made to binding the particles
of pigment to the ?ber, it is to be understood that
the ?ber may be sized before or after the mat is
light usage is employed, the ?bers rather than the 10 formed, as described, or not at all.
void spaces select the composition. Where heavy
From the foregoing it will be understood how
coats are used, the interstices are comparably
the invention may be varied within the scope of
?lled.
»~
the appended claims.
In drying, the mass and the ?bers shrink in suf
. I claim:
?ciently close degree to maintain a complete coat 15
1. The method of making a coated rigid porous
on the ?bers, and to ?ll the interstices as the
structural ?ber board which comprises ‘coating a
quantity permits. In practice the coated mat is
wet structural-board-forming mat of ?bers with
dried at 310° F. to 345° F. Thus, moisture is prac
a composition having su?icient pigment to hide
tically boiled out of the board. In light usages,
the surface ?bers, and having an aqueous vehicle
the interstices being not sealed, permit the water 20 in which is dispersed a heat-reactive binding ma
vapor to escape. Where the composition is pre
terial capable of binding the pigment to the ?ber
sent to such an extent as to seal the pores, micro
and to itself, said binding material after reaction
scopic craters may be found where the steam
by heat being set when dry at normal temperature
blows out. However, these craters do_ not alter
and exerting anadhesive action at an elevated
the continuous colored or white appearance of 25 temperature at least prior to completed thermal
the surface.
reaction, and drying the mat and the coat thereon
The drying of the preferred composition at the
simultaneously at an elevated ‘temperature to
elevated temperatures sets the binder to insoluble
form the board.
'
infusible resin form. Where the given composi
2. The method of making a coated rigid porous
tion is spread upon the board at a usage of 57 lbs. 30 structural ?ber board which comprises coating a
of composition (or 25 lbs. of pigment) per 1000
wet structural-board-forming mat of ?bers with
sq. feet, a board is obtained as follows:
a composition having sufficient pigment to hide
the surface ?bers, and having an aqueous vehicle
. Initial light-re?ectivity is 78%.
in which is dispersed heat-hardening binding
. Color-high white.
. Permanent against discoloration.
.
. A substantial retention of porosity and sound
absorbency (due to craters).
~
. Matted surface is retained, giving dull effect
lacking glare.
‘
. Texture is unaltered by coating.
35 material capable of binding the pigment to the
?ber and to itself, and drying the mat and the
coat thereon simultaneously at an elevated tem
perature to form the board.
3. The method of making a coated water-resist
40 ant rigid porous structural vegetable ?ber board
. Surface readily redecorated with oil or water
which comprises forming a water slurry of wet
vegetable ?bers carrying a water-proo?ng agent
deposited thereon, forming said slurry into a wet
9. Coating is continuous except for microscopic
the exposed ?bers of said mat and having an
. Surface is resistant to cleaning, washing, and
scu?lng.
structural-board-making mat, coating said wet
.base paints, lacquers, etc., without undue ab
45 mat with a composition having pigment to cover
sorption.
aqueous vehicle in which is dispersed heat-re
craters.
active binding material capable of binding the
There are commercially available water-dis
pigment to the ?ber and to itself, said binding
persible compositions of other resins suitable for 60 material after reaction by heat being set when dry
use in the present invention. Heat-hardening
at normal temperature and exerting an adhesive
phenol-aldehyde resins are so available. Heat
action at an elevated temperature at least prior
hardening urea-formaldehyde resins are also
to completed thermal reaction, and drying the mat
available.
.
and the tcoat thereon simultaneously at an ele
It is a practice in making boards to add ?ller 55 vated temperature to form the board.
or sizing material to the stock so as to leave the
4. The method of making a coated water-resist
same in the ?nished board, for example, a col
ant rigid porous structural vegetable ?ber board
loidal starch. This may be done with the stock
which comprises forming a water slurry of wet
of which the mat is to be coated, without in any
vegetable ?bers carrying a water-proo?ng agent
way interfering with the invention as described. 60 deposited thereon, forming said slurry into a wet
Also, where such filler is or is not present, the
'structural-board-making mat, coating said wet
surface of the wet mat may be sized with the
mat with a composition having pigment to cover
same'e?'ect by wetting the formed board with a
the exposed ?bers of said mat and having an aque
thickened sizing solution, such as gelatine or
ous vehicle in which is dispersed heat-hardening
other protein, or starch or the like. This pene 65 binding material capable of binding the pigment
trates into the surface for a limited distance, so
to the ?ber and to itself, and drying the mat and
that on drying the board, the so-treated surface
the coat thereon simultaneously at an elevated
is harder and more resistant to scu?‘. Such size
temperature to form the board.
more readily enters the board than the coating
5. The method of making a coated water-resist- .
composition with its load of pigment. By using 70 ant rigid porous structural vegetable ?ber board
such size preliminarily to using the composition,
which comprises forming a water slurry of wet
more of the binder of the composition remains in
vegetable ?bers carrying a water-proo?ng agent
the pigment coat. Thus, where a more expensive
deposited thereon, forming said slurry into a wet
binder, such as synthetic resin is employed, its
structural-board-making mat, coating said wet
quantity may be reduced. A starch solution 75 mat with a composition having pigment to cover
2,409,629
8
the exposed ?bers of said mat and having an aque
ous vehicle in which is dispersed heat-hardening
alkyd resin capable of binding the pigment to the
?ber and to itself, and drying the mat and the
mat with a composition having pigment to cover
the exposed ?bers of said mat and having an
aqueous vehicle in which is dispersed heat-hard
coat thereon at an elevated temperature to form
to itself and to the ?bers, the quantity of com
the board.
6. The method of making a coated water-resist
ening alkyd resin capable of binding the pigment
position applied being su?icient when dry to seal
the pores of the board, and drying the mat and
the coat thereon simultaneously under conditions
ant rigid porous structural vegetable ?ber board
which comprises forming a. water slurry of wet
to boil oil’ water in the mat, whereby microscopic
vegetable ?bers carrying a water-proo?ng agent 10 steam craters are formed and set in an other
deposited thereon, forming said slurry into a wet
wise continuous coat on said board.
structural-board-making mat, coating said wet
CLARK C. HERITAGE.
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