Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
PREPARATION OF I,IGMOCELLULOSIC-ISOCYA~ATE MULLED
COMPOSITIONS USING A TERPOL~MER OF A FU~J~TIO~
POLYSILOXANE-ISOCYANATE-CARBOX~LIC SUE OP. SALT
THEREOF AS RELEASE AGENT
BACKGROUND OF TOE INVENTION
The present invention relates to the compression
molding of lignocellulosic materials into composite bodies,
sheets and the like and more particularly to a method for
the preparation of particle or flake board with a pulse-
Senate binder and the use of a terpolymer which is the no-
action product of a functional polysiloxane, an isocyanate,
and a hydroxyl substituted monocarboxylic acid or metal salt
thereof as a release agent capable of providing an ease of
release and multiple release from the forming mold surfaces.
The molding of lignocellulosic and lignocellulosic-
containing fibers, particles or layers to form composite en-
tides is known. Organic dip and polyisocyanates as useful
binders for lignocellulose materials have been known for some
time and give to particle board products increased stability
and mechanical strength; see, for example, US. Patents Nos.
3,428,592; 3,4~0,189; 3,557,263; 3,636,199; 3,870,665; 3,919,
017 and 3,930,110. It is also known in the art that the
isocyanate binders are mixed with the wood particles
,~, ....
utilized as tune base for the particle ode. h wooded phi
or particle and isocyanate binder mixture i, then formed
into a mat and molded with pressure and temperature to
the desired size or shoe. water emulsion polyisocyan~te
binder systems for use with lignocellulosis particles
to prepare particle board are also Known. A reinitial
disadvantage of the use of isocyanates in the preparation
of particle 'Hoard is dye to their excellent adhesive
properties. Thus, isocyanate systems, either the
water emulsion or the straight polyisocyanate binders,
stick tenaciously to the metal caulk plates which
are employed to support the wood particles during
transporting and the pressing or molding processes.
Such poor release of the molded particle board
from the caulk or mold surface creates difficulty
in the cleaning and automatic handling of the caulk.
In order to prevent the sticking problem, external
release agents have been developed and applied to the
caulk plates or platens or mat surface as described for
example in U. S. Patent No. 4,110,397~ Other convent
tonal release agents such as oils, waxes, polishes,
silicones Ann polytetrafluoroethylene have been ~nsatis-
factory as have the specialized urethane release agents
including those used in structural foam applications.
Another method to overcome the sticking problem has
been to overlay the isocyanate bound lignocellulosic
particles with a veneer of wood as shown, for example,
in US. Patent Nos. 3,39~,110; 4,197,219 and 3,919,017,
or with the US I a release paper. These methods have
the disadvartta~e of either adding more cost to the
--2--
product or of not fully utilizing the sup wrier ox
the isocyanate binder. Many of the release agent
developed to date have to be applied during edgier
composite production cycle in large quantities to be
effective.
SUMMARY OF THE INVASION
The present invention provides for the
preparation of lignocellulosic composite articles or
sheets which comprises shaping in a mold or between
mold surfaces a mixture of lignocellulosic particles
and a polyisocyanate based binding agent, there being
provided on the mold surface or surfaces a terpolymer
of a functional polysiloxane, an isocyanate and a
hydroxyl substituted monocarboxylic acid or metal salt
thereof as a release agent, which release agent may
also be admixed with an organopolysiloxane fluid as a
delineate.
It is an object of the present invention to
provide novel compositions which serve as release agents
and provide for multiple release of the molded articles.
Another object it to provide release agents
which are readily applied and adhere to the mold surfaces.
A further object is to provide release agents
which need only be applied in small amounts.
These and other objects and advantages of this
invention will become apparent from the description of
the invention and from the claims.
--3--
RETAILED Description I THE INVENTION
The present invention comprises a method or
the preparation of lignocellulosic composite molded
articles, particularly particle board, by hounding
together wood chips or other lignocellulosic or organic
material using heat and pressure with an organic polyp
isocyanate employed as the binding agent and with tune
application of a film of release agent by dipping,
spraying or wiping of terpolymer formed by reacting a
functional polysiloxane, an isocyanate and a hydroxyl
substituted monocarboxylic acid or metal salt thereof
to the mold surface or surfaces. A functional polyp
selection hazing the formula
(Chihuahuas I OOZE So oSi(CH3)3
wherein n is an integer ox from 5 to 30, m is an integer
of from 1 to 20 and x is a group selected from -SHEA,
SUE
-SHEA, -COO, -KIWI or I is reacted with a hydroxyl
SHEA SHEA
substituted monocarboxylic acid or a hydroxyl substitute
metal salt ox the monocarboxylic acid having the formula
CH3-(CH2)~-COOz wherein hydrogen, Nay H, Cay Be, Cud, My,
K or Fe which in turn is reacted with an isocyanate having
the formula R-NCO wherein R is a group selected
from CH3-CH2)y~ -C~2(CH2)Y~CO' Al, Al or
Al Al NO
< I<
SUE -NO, Pal being hydrogen or an alkyd
on group having from 1 to 6 carbon atoms and y is an integer
of from 1 to I to form the terpol~mer release agent of
the present invention. For essentially permanent I as
or longer production use cycles the molt surface or
surfaces with film applied may be 'netted to between 75C.
and 200C. for from 1 to 5 minutes before use.
The molded lignocellulosic composite such as,
for example, particle board or Lowe board is generally
prepared by spraying the particles Whitney the polyisocyanate
binder as they are being mixed or agitated in suitable and
conventional equipment such as a blender. Suitably, the
polyisocyanate binder use levels, hosed on the weight of
oven dried (0% moisture content) lignocellulosic material
is from about 1.5 to 12 and preferably 2.5 to 5.5 weight
percent. Other materials such as fire retardants may also
be added to the particles or sprayed with the binder
during the blending or mixing step.
After forming a uniform mixture the coaxed
lignocellulosic particles are formed into a loose mat or
felt in the desired proportions onto a caulk plate of
poll hod aluminum or steel which serves to carry tune
"cake into the heated press to consolidate the wood
particles into a board of desired thickness. Temperatures
of the press are generally between about 143~ and 220C.
and pressures ox from about 100 to ~00 Sue Pressing times
are from about 1 to in preferable 3 to 5 minutes. pressing
times, temperature and pressures vary widely depending on
the thickness ox the board produced thy desired density
ox the board, the size of the lignocPllulosic particles
used, and other factors well known in the art.
on The isocyanate binding agent will generally be
I _
an organic polyisocyanate used alone jut may also ye in
admixture with another type of binding agent, e.g. a
synthetic resin glue, or in admixture with delineates Such
as propylene carbonate. the isocyanate my be applied
in liquid form as a solution in an inert solvent or
in the form of an aqueous emulsion.
The polyisocyanate component which is used in
the present invention in the binder system can ye any
organic polyisocyanate and include aliphatic, alicyclic
lo and aromatic polyisocyanates that contain at least two
isocyanate groups per molecule. Such polyisocyanates
include the diisocyanates and higher functionality
isocyanates. Mixtures ox polyisocyanates may be used
winch for example are the mixtures of dip and higher
functional polyisocyanates produced by phosgenation of
aniline-formaldehyde condensate or as described in
US. Patent Nos. 3,962,302 and 3,~19,279. The organic
polyisocyanates may be isocyanate-ended prepolymers made
by reacting under standard known conditions, an excess of
a polyisocyanate with polyol which on a polyisocyanate
to polyol basis may range from about 20:1 to 2:1 and
include for example polyethylene glycol, polypropylene
glycol, triethylene glossily, etc. as well as glycols or
polyglycols partially esterified with carboxylic acids
including polyester polyols and polyether polyols.
Illustrative of organic polyisocyanates which may be
employed include for example, Tulane- and 2,6-
diisocyanates or mixtures thereof, diphenylmethane
diisocyanate, m- and p-phenylene diisocyanates or
pa mixtures thereof, m- and p-diphenylene diisocyanates,
--6--
polyethylene polyphenyl isocyanates, naphthalene-l,
5-diisocyanate, chlorophenylene diisocyanate, I -x~lene
diisocyanate, triphenylmethane triisocyanate~ hex-
ethylene diisocyanate, 3,3'-ditolylene-4,4-diisocyanate,
battalion 1,4-diisocyanate, octylene-1,8-diisocyanate, 1,4-,
1,3- and 1,2-cyclohexylene diisocyanate and in general the
polyisocyanates disclosed in US. Patent No. 3,577,358,
3,012,008 and 3,097,191. The preferred polyisocyanates are
the di~henylmethane diisocyanate 2,4' and 4,4' isomers
including the 2,2' isomer and the higher functional
polyisocyanate and polyethylene polyphenyl isocyana~e
mixtures, which may contain from about 20 to 85 weight
percent of the diphenylmethane diisocyanate isomers.
Typical of the preferred polyisocyanates are those sold
commercially as "Rubinate-M" (~ubicon Chemicals, Ionic.
In general the organic polyisocyanates will have a
molecular weight in the range between about 100 and 10,000.
The aqueous organic polyisocyanate or isocyanate-terminated
pr~polymer emulsions are generally prepared by using any
20 of the technique known in the art for the preparation of
aqueous emulsions or dispersions prior to use of the
compositor as binder. In general the polyisocya~ate is
dispersed in water in the presence of an emulsifying or
surface active agent which may be any ox the emulsifying
agents also known in the art including anionic and non ionic
agents. Preparation of the aqueous emulsions may be
carried out as described in US. Patent Nos. 3,996,154;
4,143,014 and 4,2S7,995.
The lignocellulosic materials employed to
prepare the molded compositions using polyisocyanate
* Trade Mark
41~
binders include wood ants wood iris, sh~Jings,
sawdust, wood wool, cork bark and the like prefects from
the woodworking industry. iris, particles, etc. prom
other natural products which are lignocellulosic sun us
strati, flax residues, dried weeds and grasses, nut shells,
hulls from cereal crops such as rice and oats and tune like
may be used. In addition, the lignocellulosic materials
may be mixed with inorganic flakes or Fibrous material
suck as glass gibers or wool, mica and asbestos as well
as with rubber and plastic materials in particulate form.
the lignocellulose may contain a moisture (water) content
ox up to 25 percent by weight but prefer~ly contains
between 4 and 12 percent by weight muzzler.
The release agents of the resent invention
consisting of a terpolymer of a functional polysiloxane
an isocyanate and a hydroxyl substituted monocarboxylic
acid or metal salt thereon may be prepared by reacting,
with or without an inert solvent such as aromatic or
aliphatic hydrocarbons, e.g., Tulane, zillion, Bunyan,
Hutton, hexane, to to control and maintain solution
viscosity, at a temperature ox from about 5~C. to lSQC.
and preferably ~0C. to 110C. an excess of a sullenly
terminated functional polvsiloxane having the formula
Iffy ! IH3\
(C~1313SitOI i7toSi~OSi(CH3)3
jC~3 n X m
wherein n is from 5 to 30, m is prom 1 to I and x is
1~3
a group selected prom -Clue, -foe, -COO, -fox or -OH,
on C1~3 SHEA
with a hydroxyl substituted monocarooxylic acid or
hydroxyl substituted metal salt of one monocar~oxylic
acid having the formula CH3-(CH2)y~COOz -wherein y is an
integer of from 5 to 24 and z is a group selected fro.
hydrogen, Nay H, Cay Be, Cud, My, K or Fe thus forming
a copolymeric reaction product Russia is then reacted at
a temperature of from about 50C. to 150C. preferably
90C. to 110C. with no more than a stoichiome~ric amount
of an isocyanate having the formula RANCH wherein R
is a group selected from -CH2(CH2)yNCO~ Schick
Al Al Al Al
Al being hydrogen or an alkyd group having from l to 6
cartoon atoms and y is an integer of from 1 to 20 to form
the terpolymer. The condensation reaction to form the
terpolymer release agent may be considered completed when
no free NO can be detected by known analytical methods
such as Infer Red. The reaction with the isocyanates and
copolymer reaction product may be carried out in the
presence of from 0 to 50 weight percent inert aqueous
free (dry) solvents containing no hyroxyl groups sun as
the aromatic or aliphatic hydrocarbons, e.g. Tulane,
zillion, Hutton, hexane etc. to maintain and control
solution viscosity. 5 to 50% solids solutions may be
prepared by the condensation process but are preferably
prepared and applied as 10 to 20% solids solutions.
As indicated herein above organopolysiloxane
fluid may be employed along with the terpolymer release
agents as a delineate and are use in amounts of from 0 to 25
weight percent, preferably from lo to 20 weight percent
selection fluid mixture. The organopol~silox~ne fly
suitable for use in this invention are generally alp
terminated polysiloxane fluids having from 1 to 18 carbon
atoms bonded to the silicon atom. Examples of suitably
organopolysiloxane fluids are those having alkali radicals
such as methyl, ethyl, propel, bottle, Huxley, oxt~l, dozily,
dedecyl, tetradecyl, hexadecyl, octadecyl and the like;
aureole radicals such as phenol and naphthyl and mixtures
thereof. Generally, it is preferred that the organopoly-
selection be free of terminal-hydroxyl groups; however, a
small number of terminal-hydroxyl groups will not
materially affect the mold release composition. The
organopolysiloxane may have a minor proportion of
molecules with only one hydroxyl group or there may be
a small number of molecules present carrying in excess of
two hydroxyl groups. However, as mentioned previously, it
is preferred that the organopolysiloxane be substantially
free of hydrox~l groups. In general, the polysiloxane
fluids should have a molecular weight of between about
3,000 and 90,000 which is equivalent to a viscosity of
between about 50 and 100,000 centipoises, preferably from
about 100 to 5,000 centipoises. Optimum results have been
obtained in the lower portion of these ranges such as from
about 200 to S00 centipoises. In addition, it is possible
to combine high and low viscosity fluids to form a fluid
having the desired viscosity range.
The organopolysiloxane fluids used in accordance
with this invention may be represented by the formula
-10-
R' r R' R'
R-Si-¦ Ooze- I Ooze
l l l l l
I y
wherein OR and R" which may be the same or different
represent organic grouts having from 1 to I carbon atoms,
preferably alkyd groups having prom 1 to 4 carbon atoms,
and y has a value of from 80 to about 150,0~0.
The novel mold release agents of the instant
invention, whether the polysiloxane-monocarboxylic acid
or salt-isoc~anate terpolymer alone or the terpolymer
admixed with an organopolysiloxane fluid, may be employed
in a liquid organic solvent which would preferably be
sufficiently volatile to vaporize during the application
process. Preferred solvents include Tulane, zillion,
Bunyan, naphtha type solvents, higher I to C10 alcohols
such as isobutanol and hydrocarbon solvents such as
perchloroethylene.
The functional polysiloxane-monocarboxylic acid
or salt-isocyanate terpolymer release aunt may be applied
to the mold surfaces as a concentrated or dilute solution
or as a dispersion. It is preferred that the release
agent composition be dissolved in a volatile organic
solvent such as a mixture ox Tulane and isobutanol an
then sprayed, wiped or brushed onto the mold surfaces in
the form of a thin elm. This may best be obtained by
rubbing the mold surface or surfaces with a swab saturated
with a solution of the release composition. However, when
practical, the mold surfaces may be sprayer with the
I composition to form a thin film thereon.
Once the release composition nay teen Apple
to the mold surfaces, it may be used immediately.
however, it is preferred that the coating be dried
especially when an organic solvent has been used. -lore
preferably, as indicated hereinbe~ore the coated mold
surfaces are heated to between about 75 to 200C. for
from 1 to 5 minutes to fill all pores and openings and
to provide for an essentially permanent release or longer
production use cycles.
The following examples are provided to illustrate
the invention in accordance with the principles of this
invention, including examples ox a comparative nature,
but are not to be construed as limiting the invention
in any way except as indicated by the appended claims.
EXAMPLE 1
580 grams of pine wood chips dried to a
moisture content of 6 percent were placed in an open
tumbler-mixer. During tumbling 16 grams ox a diphenyl-
methane diisocyanate-polyme~hylene polyphenylisocyanate
(PMDI) mixture having a 46.S percent diphenylmethane
diisocyanate content as a binder was sprayed evenly onto
the wood chips by an air pressurized system. two new
aluminum caulk plates 12" x 12" x 3/16" were wiped with
a cloth saturated with a terpolymer release agent mixture
of 10 parts by weight of a polymerization reaction product
of a sullenly (-SHEA) terminated polydimetnyl selection,
having a molecular weight ox 28,000, 12-hydroxy Starkey
acid, and a diphenylmethane diisocyan~te-polymethylene
polyPhenyl isocyanate (PMDI) mixture having a 46.5~
diphenylmethane diisocyanate content and 90 parts by
-12-
weight Tulane. the terpolymer Teas prepared by charging
50 grams of silanol(-CH2OH) terminated polydimethyl
siloxane(MW 2~,000) and 6 grams 12-hydroxy Starkey acid
into a 250ml reaction flask in 50% by weight Tulane.
The reaction was run for 3 1/2 hours at 90C. in nitrogen
with steady stirring. The reaction was cooled and .23
grams of diphenylmethane diisocyanate-pol~ymethylene
polyphenyl isocyanate (PMDI) having 46.5~ diphenylmet'n~n~
diisocyanate was charged into the reaction flask. The
complete mixture of materials was reacted for 4 additional
hours at 100C. in nitrogen under steady stirring at which
time no tree NO could be detected by infer red analysis.
Tulane was added to make a solution of 10% 501 its. Tune
polyisocyanate coated wood chips were then preformed in
a box 10.5 inches square and 12 inches high which was
supported by one of the terpolymer release agent coated
caulk plates and repressed to form a thick mat. The box
; was then taken out and the second coated caulk plate placed
on top ox the mat. Thy whole assembly way subjected to
a temperature of 190C.~ pressed to stops at a thickness
of 13mm and Hoyle for 4 minute and the pressure released.
The lignocellulosic (wood chip board) composite was easily
released from the caulk plates r The board making procedure
as above way repeated four additional times using the same
originally coated caulk plates with easy release ox the
composite.
EXAMPLE 2
he procedure ox Example 1 was repeated except
that the aluminum caulk plots wiped with the sullenly
terminated poly~imethyl selection hyrax Starkey acid-
I
isocyanate terpolymer release agent mixture was ~atedat l76C. for 3 minutes prior to use. Six repeated cycles
ox board reparation and release a l30C. were recorded.
EXAMPLES 3 to _
Various terpolymers of sullenly terminated
pol~dimethyl selections, molecular weight 28,0~0, -with a
monocarboxylic acid or metal salt thereof were Prepared
by reacting l part by weight of toe sullenly and l part by
weight of the acid or metal salt in a 250 ml reaction
lo flask with 50~ by weight Tulane. The siloxane-acid
reaction was run for four hours at ~5C. in nitrogen
with stirring, cooled and then reacted with l part by
weight of di~henylmethane diisocyanate-polymethylene
polyisocyanate (PMDI) hazing 46.5% diphenyl methane
diisocyanate which reaction was run for 4 hours at 100C.
in nitrogen with stirring until no free NO could be
detected by infer red analysis. ~oluene was added to
provide a lo solids solution. The procedure of Example 1
was repute to Produce particle hoar using the release
agents and giving the release cycles as indicated below.
Terpolymer Release Cycles
E ample No. Release Agent at 190C.
3 ,Silanol(-CH2OH) terminated
Polydimethyl Selection and
12-Hydroxy Calcium Stewart 4
with PMDI
4 Sullenly (-SHEA) terminated
Polydimethyl Selection and
12-Hydroxy Iron turret 5
with PMOI
Cardinal (-COIN) terminated
Polydim2thyl Selection and
2-Hydroxy Potassium Owlet 6
with PMDI
Terpol~mer Release I 5
Example Jo. Release Agent at lgOC,
6 Car boxy (-COO) terminated
Polydimethyl Selection and
12-~ydroxy Static Acid 7
with PMDI
7 Sullenly (-C~20H) terminated
Polydimethyl Selection with
2-~y~roxy Caprice (decanoic)
Acid and phenylisocyanate 5
8 Sullenly (-~H20H) terminated
Pol~dimethyl Selection with
12-~ydroxy Palmitic (hexadecanoic)
and hexamethylene diisocyanate
EXAMPLE 9
The procedure of Example 2 was repeated
employing 85% of the terpolymer of example 1 mixed with
15~ polysiloxane fluid and diluted to a 10% solids
solution with Tulane. Six repeated cycles of particle
board preparation and release at 190C. were recorded.
EXAMPLE lo
The procedure of Example 2 was repeated
employing an ~0:20 mixture of the terpolymer of Example 5
an polydimethyl selection fluid diluted to 10% in a 50:50
mixture of Tulane and isobutanol. five repeated suckle
ox particle board preparation and release at 190C. were
recorded.
EXAMPLE if CONTROL
I__
Example l was repeated except that no release
agent way applied to the caulk plates. The pressed lingo-
cellulosic composite could not be released even after
cooling down.
EXAMPLE 12 CONTROL
Examples 1 and were repeated except that the
on caulk plate in three composite preparations were wipe
--15--
with a 15% solution of zinc Stewart, aluminum st~arag~
and lithium Stewart in isobutanol, Only on cycle of
release was recorded with each when hot (19~C,).
