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Description  |
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BACKGROUND OF THE INVENTION
Polyurethane foams are made from polyfunctional isocyanates and
hydroxyl-containing polymers, along with the catalysts necessary to
control the rate and type of reaction, foaming agents, and other additives
necessary to control the surface chemistry of the process. The methods of
production of polyurethane foams are well known. The Kirk-Othmer
Encyclopedia of Chemical Technology, John Wiley and Sons, Third Edition
and Saunders and Frisch, Polyurethanes, Krieger Publishing, are excellent
references for the chemistry of polyurethane foams. The uses of
polyurethane foams are also well known. For example, foamed polyurethane
compositions have found widespread use in the fields of insulation and
structural reinforcement. Flexible polyurethane foams are used as
cushioning in furniture and automobiles and as acoustical deadening layers
in cabinets such as computer housings Melamine crystal is frequently used
in these polyurethane foams to make the foams fire retardant U.S. Pat.
Nos. 4,385,131 and 4,221,875 describe the incorporation of melamine into
foams for resistance to both smoldering combustion and flaming combustion.
One commercial process for formulation of a fire resistant polyurethane
foam consists of blending a first steam combining polyol and melamine with
a second stream combining isocyanate and foaming agent with a third stream
combining water, surfactant and reaction catalyst. The first, second and
third streams are mixed in a multi-stream "mixing head". On exiting from
the mixing head the polyurethane forms in a foamed state. In this process,
other known materials, such as extenders, fillers and pigments are
commonly employed as well.
Several major difficulties are encountered when combining polyol and
melamine in a mixing tank to prepare the first stream in this commercial
process. When a blend having a 1 to 1 weight ratio of polyether polyol to
melamine is prepared the viscosity levels are excessively high for
conventional commercial equipment and the uniformity of the blend is only
temporary, the melamine separates out and settles to the bottom of the
mixing tank. In the mixing tank, the viscosity of the melamine-polyol
blends, measured at typical shear levels of 10 to 20 seconds.sup.-1,
ranges from 7,000 to 15,000 centipoise, while in the pipe network system
the viscosity measured at typical shear levels of 50.sup.-1 to 100
seconds.sup.-1 ranges from 6000 to 9000 centipoise. These viscosities are
too high for the equipment in existing foam manufacturing facilities where
high viscosities lead to excessive pressure drops that cannot be handled
by conventional pumping systems and also lead to excessively slow flow
rates for production. It is preferred to have viscosities less than 6000
centipoise at shear levels of 50.sup.-1 seconds. If agitation of the blend
is interrupted, as for example, by equipment malfunction, the melamine
settles out forming a compact dense sediment which cannot be resuspended
by mixing. Attempts to use an impeller to resuspend the sediment can
result in damage to the impeller motor when the sediment is deep enough to
cover the blades. If the compacted dense sediment layer of melamine forms
in a tank, its removal is difficult and may even require workers to enter
the tank to remove it manually. The settling out of melamine also creates
a severe specific gravity gradient from the top to the bottom of the
mixing tank which leads to non-uniform distribution of melamine in the
final flexible foam product. Major problems are thus encountered in
production which are directly caused by the inability to create and
maintain a stable suspension of melamine and polyol.
OBJECT OF THE INVENTION
It is accordingly an object of this invention to provide a stable melamine
polyol suspension. Another object of this invention is to provide a
solution to the problem of excessive viscosities of the polyether
polyol-melamine blend and a solution to the problem of non-uniform
melamine distribution. Another object of this invention is the attaining
of high concentrations of fine melamine particles in the foam product for
optimum fire retardancy properties without excessive viscosities in the
polyether-polyol melamine blend.
SUMMARY OF THE INVENTION
In accordance with the present invention a novel process is provided in
which polyether-polyol melamine blends show lowered viscosities
appropriate for conventional commercial equipment and are stable
suspensions having uniform melamine distribution. The polyether
polyol-melamine blend made by the process of the present invention
incorporates higher concentrations of fine melamine particles at
acceptable viscosity levels than polyol-melamine blends made
conventionally. The resulting foam products have substantially superior
fire retardancy because they contain a higher concentration and uniform
distribution of melamine.
This invention is a method of manufacturing polyurethane foams wherein a
first reaction stream containing polyol and melamine is combined with a
second reaction stream containing isocyanate and foaming agent and a third
reaction stream containing surfactant, catalyst and water, the improvement
which comprises the addition of an effective stabilizing amount of an
amine compound selected from the group consisting of diethanolamine,
ethanolamine, trihexylamine or mixtures thereof to said first reaction
stream creating a stable polyol-melamine suspension stream. In one
embodiment this invention further comprises the addition of
trichlorofluoromethane to said first reaction stream.
It has been discovered that this addition of certain amine compounds to the
polyol-melamine stream has a dramatic effect on the stability of the
polyol-melamine suspension. Useful amine compounds include diethanolamine,
ethanolamine and trihexylamine. The preferred amine compound is
diethanolamine. Heretofore no one has added the amine compound to the
polyol-melamine stream to make a stable polyol-melamine suspension which
also has viscosities which conventional equipment tolerates even at high
levels of melamine to polyol.
The literature contains numerous references to the use of amine compounds
for various other purposes in polyurethane reactions. Among these
references; Soviet Patent No. 891,698 shows the use of tetrahydroxy
propylene diamine in the production of a polyurethane foam made from; a
polyether containing chloro-hydroxyl groups, polyisocyanate and melamine.
The abstract of No. 891,698 does not address the question of
melamine-polyol suspension stability. Soviet Patent No. 891,698 apparently
uses the tetrahydroxy propylene diamine compound as a catalyst for the
formation of polyurethane foam.
U.S. Pat. No. 4,500,655, using diethanolamine in a different way, is
directed to polyols for use in polyurethane foams, the polyols being
prepared by first reacting phenol, formaldehyde and diethanolamine to make
a Mannich condensate. This condensate is then propoxylated with propylene
oxide. The propoxylation product is reacted with melamine and a lower
alkylene carbonate to make the polyol component for use in subsequent
polyurethane foam manufacture. This reference thus uses diethanolamine as
a reactant in the preparation of the polyol component. U.S. Pat. No.
4,145,488 similarly describes the use of the oxyalkylated Mannich reaction
product of phenol, formaldehyde and diethanolamine as the polyol component
of a polyurethane foam composition. The problem of polyol-melamine
suspension stability is not addressed by either U.S. Pat. No. 4,500,655 or
U.S. Pat. No. 4,145,488.
U.S. Pat. No. 4,296,213 describes the preparation of a polyurea polymer
polyol by reacting a hydroxyl-containing amine, a polyether polyol and an
organic polyisocyanate. For example, toluene diisocyanate was added to a
mixture of polyether triol and diethanolamine to form a polyurea polymer
polyol. The polyurea polymer polyol was then reacted with additional
polyisocyanate to form a polyurethane product. This reference did not
relate to the stability of melamine-polyol suspensions.
U.S Pat. No. 3,438,908 describes the addition of a stabilizing tertiary
amine to a blend of polyol and tertiary amine catalyst. Thus stabilized
the polyol-catalyst blend can be stored until used with polyisocyanate and
retains full catalytic activity during storage. The stabilizing tertiary
amines had half the catalytic activity of the catalytic tertiary amines.
This reference did not relate to the stability of melamine-polyol blends
nor did it mention diethanolamine.
U.S. Pat. Nos. 3,399,151 and 4,221,875 and British Pat. No. 1,384,771
describe the use of tertiary amines as reaction catalysts for the
production of polyurethane from polyols and polyisocyanates.
Diethanolamine is among the compounds well known as catalysts for the
production of polyurethane foams according to British Pat. No. 1,384,771.
No references were identified which relate to the use of amine stabilizing
agents with melamine-polyol blends.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram of the commercial process in which this invention is
practiced Melamine crystal in the delumper (1) is supplied through the
continuous feeder (2) to mixing tank (6) which is provided with impeller
blades operated by motor (7). Polyol enters tank (6) through line(3), the
diethanolamine of this invention enters tank (6) through line (4) and
trichlorofluoromethane optionally enters tank (6) through line (5). The
melamine-poluol suspension first reaction stream exits tank (6) through
line (8) which contains a pump and a recirculation line (9) having an
optional in-line mixer. the melamine-polyol suspension first reaction
stream is then combined in mixing head (12) with the second reaction
stream of blowing agent and polyisocyanate in line (11) and with the third
reaction stream of surfactant, catalysts and water in line (10). The fire
retardant polyurethane foam exits line (13) in a foamed state.
FIG. 2 graphically portrays the viscosity in centipoise versus shear rate
in reciprocal seconds for the formulations of Examples 1, 2 and 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In a preferred embodiment the amine added to the first reaction stream
containing polyol and melamine is an alkyl hydroxyl amine. In the most
preferred embodiment the amine added to the first reaction stream to make
the stable suspension is the secondary amine diethanolamine. In another
preferred embodiment the foaming agent trichlorofluoromethane and
diethanolamine are both added to this first reaction stream containing
polyol and melamine to make the stable suspension.
The remainder of the process for making foams is conventional. In this
process the first reaction stream is combined with a second reaction
stream containing polyisocyanate and foaming agent and a third reaction
stream containing surfactant, reaction catalyst and water. The polyol
component of the first stream and the polyisocyanate, foaming agent,
surfactant, and reaction catalyst of the second and third streams may be
any which have been used in the production of polyurethane foam.
As the polyol component there may be used: polyesters made by reaction of
an acid such as adipic acid and a polyhydric alcohol, polyethers made by
the addition of an alkylene oxide such as ethylene oxide or propylene
oxide to ethylene glycol, glycerol, propylene glycol, diethylene triamine,
aromatic diamines, sucrose, sorbital and the like and other compounds
having two terminal hydroxyl groups. The preferred polyol for use in this
invention is Pluracol Polyol C-133 available from BASF Wyandotte Corp.,
Parsippany, N.J., a polyether polyol made from propylene glycol and
ethylene glycol in a mole ratio of 2.7 to 1.0. The Pluracol Polyol C-133
has a hydroxyl number of 36.0 mg KOH/gm and an acid number of 0.015.
Although in the preferred embodiment of the invention 100 parts polyol are
combined with 100 parts melamine it is also acceptable to use from 20 to
120 parts melamine with 100 parts polyol depending on the degree of fire
retardancy desired.
As polyisocyanates there may be used aromatic isocyanates such as
tolylenediisocyanate, diphenylmethane diisocyanate, alicyclic isocyanates
such as hydrogenated tolylene diisocyanate, or aliphatic isocyanates such
as hexamethylene diisocyanate.
The melamine crystal used was that obtained from Melamine Chemicals, Inc.
(MCI), Donaldsonville, La. This melamine is available in different grades
having varying amounts of fine particles. "Fines" are defined as those
particles passing through a 325 mesh sieve. Unground MCI Melamine has
about 20% fines. Superfine MCI melamine has about 85% fines.
In the manufacture of fire resistant polyurethane foam maximizing the
concentration of fine melamine particles consistent with acceptable
viscosity is highly desired to obtain good flame retardant properties in
the foam product. In the past, melamine with more than 20% concentrations
of fine particles have led to unstable melamine-polyol blends of excessive
viscosity. With the process of this invention melamine with concentrations
of fine particles greater than 30 percent can be suspended in polyol
without such excessive viscosity. It is even possible to use melamine with
64% fine particles to make foams when using the additives and process of
this invention. Melamine is used in the preferred embodiment in the amount
of 100 parts melamine to 100 parts polyol, however from 20 parts to 120
parts melamine may be used with 100 parts polyol.
Amines useful in the practice of this invention include tertiary amines
such as trihexylamine and alkanol amines such as diethanolamine and
ethanolamine. Diethanolamine is particularly preferred. From 0.5 to 5.0
parts diethanolamine are used with 100 parts polyol in a preferred
embodiment, while from 1.0 to 2.0 parts diethanolamine are used with 100
parts polyol in a more preferred embodiment.
Trichlorofluoromethane, available from DuPont, Wilmington, Del. under the
trademark FREON, is the preferred foaming agent used in the practice of
this invention. Other foaming agents useful in this invention include the
halogenated hydrocarbons difluorodichloromethane,
1,1,2-trichloro-1,2,2-trifluoroethane, methylene chloride, chloroform and
carbon tetrachloride. In a preferred embodiment from 2 to 10 parts
trichlorofluoromethane, sold as FREON R-11, are used with 100 parts
polyol.
The following Examples show how the present invention has been practiced
but should not be construed as limiting. In this application, all
proportions and percentages are by weight unless otherwise expressly
indicated. Also, all citations referenced herein are expressly
incorporated herein by references.
Examples 1 through 7 will establish the effectiveness of alkyl amines such
as diethanolamine, ethanolamine and trihexylamine in providing stable
polyol-melamine suspensions having commercially practical viscosities.
Examples 1 and 1A demonstrate the problems encountered in conventional
polyol-melamine mixtures. Example 2 demonstrates the improvement in
accordance with this invention utilizing diethanolamine (DEOA) Example 3
demonstrates the improvement in accordance with this invention utilizing
the foaming agent trichlorofluoromethane and diethanolamine. The results
of Examples 1, 2 and 3 are reported in FIG. 2 where the viscosity in
centipoise is shown versus shear rate in reciprocal seconds. Example 4
demonstrates the improvement utilizing trihexylamine. Example 4A
demonstrates the improvement utilizing trichlorofluoromethane and
trihexylamine. Example 5 demonstrates the excessive viscosities
encountered in the absence of diethanolamine and the acceptable
viscosities attained with diethanolamine at from 8% to 33% levels of fine
particles of melamine. Example 6 provides comparative testing of related
amine compounds. Example 7 provides the commercial embodiment of this
invention.
EXAMPLE 1
(4371-90)
A control experiment was run in which the ingredients combined were the
polyol and melamine. Neither trichlorofluoromethane nor amine were used.
To a 2 liter reaction flask having an impeller of 5.8 cm diameter and
calculated shear rate of 33 sec.sup.-1 ("low shear") containing BASF
polyol C-133 in the amount of 400 grams, 400 grams of unground MCI
melamine containing 19.2% fines was added in 100 gram portions over a 10
minute interval while mixing at 200 RPM. Mixing was continued for an
additional 20 minutes. The viscosity measured at 50.sup.-1 sec. was 7000
centipoise. A 500 ml. portion was stored in a 500 ml. graduated cylinder.
After seven days storage examination of the stored blend showed a hard,
compact layer of sediment reaching the 60 ml. level. The suspension also
showed a large gradient in specific gravity from the top (1.13 gm/cc) to
the bottom (1.31 gm/cc) of the cylinder. The sediment layer would not
redisperse using ordinary mixing methods. The blend prepared without
trichlorofluoromethane or amine was shown to be unstable and non- uniform.
EXAMPLE 1A
(4371-87)
A further experiment was run to evaluate the effect of shear rate during
addition of melamine to polyol on the stability of the melamine-polyol
suspensions. Following the procedure of Example 1 melamine was added to
polyol in a flask having an impeller of 5.8 cm diameter and a calculated
shear rate of 167 sec.sup.-1 ("high shear"). After seven days storage
examination of the stored blend showed a layer of sediment reaching the
107.5 ml level in a 500 ml graduated cylinder (4371.87). A comparison of
the results from "low shear" mixing of Example 1 and "high shear" mixing
of Example 1A shows that low shear mixing produces less sediment in a
stored melamine-polyol blend.
EXAMPLE 2
(4509-17)
In this experiment the effect of adding a secondary dialkanol amine to the
polyol-melamine blend was examined. To a 2 liter reaction flask was added
BASF polyol C-133 in the amount of 400 grams and Union Carbide
diethanolamine in the amount of 4.8 grams. After mixing at 200 RPM for one
minute 400 grams unground MCI melamine containing 19.2% fines was added in
100 gram portions over a nine minute interval. Mixing was continued for an
additional twenty minutes The viscosity measured at 50.sup.-1 sec was 5650
centipoise. A 500 ml portion was stored and inspected after 7 days. No
sediment was detected at the bottom of the cylinder. A 35 ml puddle of
clearer polyol had separated at the surface of the sample. The specific
gravity of this material at the top of the stored suspension was 1.04; the
specific gravity of the remaining 465 mls of material at the bottom of the
stored suspension ranged from 1.189 at the top to 1.22 at the bottom. The
very modest mixing accomplished by simple single inversion of the cylinder
restored the sample to a uniform suspension. The blend prepared from
polyol, diethanolamine and melamine was found to be storage stable.
EXAMPLE 3
(4509-18)
In this experiment the effect of combining polyol, melamine, secondary
dialkanol amine and trichlorofluoromethane was examined BASF Polyol C-133
in the amount of 400 grams and 4.8 grams Union Carbide diethanolamine were
added to a 2 liter flask. After 1 minute blending 400 grams unground
melamine containing 19.2% fines was added in 100 gram portions over a 9
minute interval. Mixing at 200 RPM was continued for 5 minutes.
Trichlorofluoromethane in the amount of 20 grams was added and mixing was
continued for 8 minutes. The viscosity measured at 50.sup.-1 was 4880
centipoise. A 500 ml. portion was stored and inspected after 7 days. There
was no measurable sediment on the bottom of the cylinder. A 15 ml puddle
of clearer polyol appeared on the surface of the sample. The specific
gravity between the 485 ml mark and the bottom of the suspension ranged
from 1.196 to 1.246. Very modest mixing accomplished by a simple single
inversion of the cylinder restored the sample to a uniform suspension. The
blend prepared from polyol, melamine, secondary amine and
trichlorofluoromethane was found to be storage stable
The viscosities of the blends made in Examples 1, 2 and 3 were measured at
varying shear rates and are reported in FIG. 2. At shear rates from
10.sup.-1 sec. to 100.sup.-1 seconds the Example 1 product had the highest
viscosities. The effect of the diethanolamine on lowering viscosity in
Example 2 is apparent. The lowest FIG. 2 viscosities at shear rates
between 10.sup.-1 sec and 100 sec are those from Example 3 where
diethanolamine and trichlorofluoromethane were both added to the
melamine-polyol blend.
Example 3A illustes the effect of using trichlorofluoromethane alone with
the melamine-polyol blend.
EXAMPLE 3A
(4509-14)
In this experiment BASF Polyol C-133 in the amount of 400 grams and 5.6
grams Dow Corning surfactant 4053 were blended in a 2 liter reaction
flask and mixed for 5 minutes at 200 RPM. Unground melamine having 19.2%
fines was added in the amount of 400 grams in 100 gram portions over a 10
minute interval. Trichlorofluoromethane in the amount of 20 grams was
added. The viscosity measured at 50 sec was 4390 centipoise. A 100 ml
portion was stored and inspected after 3 days. An extensive layer of soft
mushy sediment reaching to between the 45 ml and the 50 ml marks was
noted. The blend prepared by combining polyol, melamine and
trichlorofluoromethane was found to be unstable on storage.
EXAMPLE 4
(4509-3)
In this experiment the effect of combining polyol, melamine and
trihexylamine was examined BASF polyol C-133 in the amount of 400 grams,
Dow Corning 193 Surfactant in the amount of 5.6 grams and 4.8 grams
trihexylamine were added to a 2 liter reaction flask and mixed for 20
minutes. Unground melamine containing 19.2% fines in the amount of 400
grams was added over a 9 minute interval while mixing at 250 RPM. Mixing
was continued for 18 additional minutes A 500 ml. portion was stored and
inspected after 7 days. There was a 70 ml. puddle of clearer liquid at the
top of the sample with a specific gravity of 1.046. There was no
measurable sediment at the bottom of the sample. The specific gravity for
the remaining 430 mls of the suspension ranged from 1.239 at the top of
the sample to 1.263 at the bottom. The blend prepared by combining polyol,
melamine and tertiary alkyl amine was found to be storage stable.
Example 4 A illustrates the effect of adding both the tertiary amine,
trihexylamine, and trichlorofluoromethane to the melamine-polyol blend.
EXAMPLE 4A
(4509-2)
Following the procedure of Example 4 400 grams unground melamine containing
19.2% fines was added over a 9 minute internal to 400 grams BASF polyol
C-133 and 5.6 grams Dow Corning 193 surfactant. After 25 minutes mixing 20
grams trichlorofluoromethane were added followed by 4.8 grams
trihexylamine. A 500 ml. portion was stored and inspected after 7 days.
There was a 40 ml. puddle of clearer liquid with a specific gravity of
1.046 at the top of the sample. There was no sedimentation at the bottom
of the sample. The specific gravity for the remaining 460 mls of the
suspension ranged from 1:176 at the top of the sample to 1.209 at the
bottom. The blend prepared by combining polyol, melamine, tertiary alkyl
amine (trihexylamine) and trichlorofluoromethane was found to be storage
stable.
EXAMPLE 5
In this experiment the effect of using melamine having differing levels of
"fines" was examined "Fines" are defined as those particles passing
through a 325 mesh sieve. The procedure of Example 1 was followed in those
tests where no amine was used. The procedure of Example 2 was followed in
those tests where diethanol amine (DEOA) was used. The different melamine
samples tested were first measured for the level of "fines" using standard
screen tests. (ASTM Number D 1921-63 reapproved 1975). Four hundred gram
portions of each type of melamine were added to polyol as described in
Examples 1 and 2 as appropriate. The viscosities of the suspensions were
measured and 500 ml examples of the suspensions were examined for
stability 7 days after preparation. The results appear in Table 1 below.
It can be concluded that the viscosities of melamine-polyol suspensions
made without diethanolamine are excessively high for conventional
commercial equipment. The suspensions made with diethanolamine have lower
and useful viscosities at the high levels of melamine fines desirable for
optimium fire retardant properties in the polyurethane foam product. The
concentration of fine particles in the melamine can be varied from 8% to
64% with little change in the viscosity of the polyol-melamine suspension
when diethanolamine is used to stabilize the polyol-melamine suspension.
Without use of diethanolamine stabilizer the use of melamine having from
8% to 85% fine particles provides only unstable melamine-polyol blends.
TABLE 1
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Level of Fines in Melamine and the
Viscosity of the Polyol-Melamine Suspension
with and without Diethanolamine
Without DEOA With DEOA
Mel- % Viscosity
Suspension
Viscosity
Suspension
amine Fines 50 sec-1 Stability
50 sec-1
Stability
______________________________________
MCI 7.9 6580 Unstable
6,500 Stable*
Un- 4509-70** 4509-22
ground 19.2 7,000 Unstable
5,670 Stable
4371-90 4509-8
33.2 7,100 Unstable
5,510 Stable
4509-70 4509-8
MCI 64 7,100 Unstable
6,000 Stable
Ground 4371-84 4509-4
MCI 85.4 13,000 Unstable
10,500 Stable
Superfine 4371-83 4509-11
______________________________________
*Definition of "Stable": No layer of sediment in sample on standing 7
days, specific gravity gradient is very small, there may be a small amoun
of polyol that has separated and risen to the surface of the sample but
very minimal agitation is required to redisperse this polyol and yield a
uniform suspension.
**Laboratory notebook reference
This Example 6 illustrates the results obtained when comparative testing is
done on a number of compounds related to diethanolamine.
EXAMPLE 6
(4509-59)
The procedure of Example 2 was followed substituting various
amine-containing compounds for the diethanolamine of Example 2. The
compounds tested and amounts used are reported in Table 2 below along with
the results obtained. After 7 days storage the quality of the suspension
was measured by attempting to empty the graduated cylinder in which the
suspension was stored. The level at which the suspension was too stiff to
pour out from the cylinder was recorded.
TABLE 2
______________________________________
Testing of Amine Compounds
Amine Compound
Suspension Quality of
g./400 g. polyol Level of
Sediment in 500 ml stored
Suspension after 7 days
______________________________________
4509-59-1
Ethanolamine 2.8 g 300 ml
4509-68-4
Ethanolamine 5.6 g 0 ml
4509-65-1
Ethanolamine 2.8 g 0 ml
4509-68-1
Ethanolamine 2.8 g 0 ml
4509-59-2
Isopropanolamine 3.4 g 300 ml
4509-65-2
Isopropanolamine 3.4 g 0 ml
4509-68-2
Isopropanolamine 3.4 g 270 ml
4509-59-3
2-Amino, 2-Methyl-Propanol
4.8 g 290 ml
amine
4509-65-3
2-Amino, 2-Methyl-Propanol
4.8 g 250 ml
amine
4509-59-4
Amino, Trimethoxy Methane
5.5 g 275 ml
4509-65-4
Amino, Trimethoxy Methane
5.5 g 260 ml
4509-59-5
Diisopropanolamine
7.2 g 275 ml
4509-65-6
Diisopropanolamine
7.2 g 250 ml
4509-61-1
Diethanolamine 4.8 g 0 ml
4509-65-6
Diethanolamine 4.8 g 0 ml
4509-68-3
Diethanolamine 4.8 g 0 ml
4371-90 Control: omit amine 60 ml
______________________________________
The results are that, among the compounds related to diethanolamine, the
ethanolamine compound was effective in producing a stable polyol-melamine
blend in three of four trials. The fourther unsuccessful trial (4509-59-1)
is believed to be anomalous and is reported here for the sake of
completeness. Two of three trials with isopropanolamine showed no
stabilizing effect on the polyol-melamine mixture. The third successful
trial (4509-65-2) with isopropanolamine is believed to be anomalous and is
reported here for the sake of completeness. The effective stabilizing
compounds which form stable polyol-melamine suspensions are, therefore,
diethanolamine, ethanolamine and trihexylamine (see Example 4). The
Example 6 tests reveal that the other amine compounds tested;
isopropanolamine, 2-amino, 2 methylpropanolamine, amino, trimethoxymethane
and diisopropanolamine do not act as stabilizing agents when added to
polyol-melamine mixtures. There is no apparent explanation of the
stabilizing effect of diethanolamine, ethanolamine and trihexylamine or of
the absence of that stabilizing effect with isopropanolamine, 2 amino 2
methyl propanolamine, amino trimethoxymethane and diisopropanolamine.
This Example 7 illustrates the pilot plant commercial embodiment of this
invention.
EXAMPLE 7
A mixing tank must be used which is capable of handling a suspension with a
high solids content. The power density of the mixing equipment should be
at least 3 horsepower/100 gallons. To 100 parts BASF Pluracol Polyol C-133
are added 1 part diethanolamine. After blending is complete 100 parts
melamine are added in separate increments amounting to 25% of the total
charge in each increment. Each increment must be dispersed before adding
the next increment. After the melamine is charged and dispersed blending
must continue until a representative sample is smooth and free of clumps.
Minimum pilot plant blending times have been 2 to 4 hours.
Tests at high power densities of 15 horsepower/1000 gallons resulted in
suspensions having greater sediment and less stability than tests at low
power densities of 5 horsepower/1000 gallons. Recommended power densities
should be at least 3 horsepower/1000 gallons up to about 10
horsepower/1000 gallons.
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