Note: Descriptions are shown in the official language in which they were submitted.
- I 334606
Mo-2984
PU-243B
USE OF ESTER GROUP CONTAINING
POLYOLS IN A RIM PROCESS
BACKGROUND OF THE INVENTION
Polyester polyols produced from dicarboxylic
acid anhydrides, polyols and polyepoxides are known. In
U.S. Patent 4,403,093, such polyester polyols are
produced by first reacting a 1,2-dicarboxylic acid
anhydride with a polyol under conditions sufficient to
form a half-ester with substantially no polyester-
ification product. The resultant half-ester is then
reacted with a polyepoxide under conditions sufficient to
form an ungelled polyester oligomer. The resultant
polyester oligomers are described as being useful as
resinous binders in high solid containing compositions.
Polyester polyols produced from aromatic acids
and polyoxyethylene glycols are also known and are
described as being useful in the production of rigid
polyurethane foams (see, e.g., U.S. Patent 4,039,487 and
German Auslegeschrift 1,155,908).
Finally, in the known polyurethane/urea
reaction injection molding (RIM) process, a wide variety
of different polyols have been suggested (see e.g., U.S.
Patents 3,726,952, 4,218,543, 4,288,564, 4,442,235,
4,519,965, 4,581,396 and British Patent 1,534,258, and
Canadian Application Serial No. 557,202, filed January
22, 1988. Similarly, polyester polyols of various types
have been suggested for use in the RIM process (see,
e.g., U.S. Patents 4,481,309, 4,590,219 and 4,595,705).
DESCRIPTION OF THE INVENTION
30 The present invention is directed to the
discovery that when certain polyester polyols are used
in the RIM process, the resultant part exhibits
unexpectedly improved flame properties. More
particularly, the present invention is directed to an
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improved process for the production of polyurethane
moldings by reacting a reaction mixture comprising
a) a polyisocyanate,
b) an isocyanate-reactive material having a
molecular weight of from about 840 to about
5,000 and
c) a chain extender and/or cross-linker,
said reaction mixture being processed as a
one-shot system by the RIM process at an
isocyanate index of from about 70 to about 130,
the improvement wherein component b) comprises
a polyester polyol selected from the group
consisting of
(i) polyester polyol having the idealized
structure
O
~I 11
R-~ O-C-R'-C-O-X t OH)n]m
(ii) a polyester polyol having the idealized
structure
O O
H- O-X'-O-C-R"-C -p O-X'-OH , and
(iii) mixtures thereof,
wherein
R represents the residue of a polyepoxide after ring
opening with a carboxylic acid group,
R' represents the residue of a cyclic anhydride,
25 R" represents the residue of an aromatic anhydride or
aromatic dicarboxylic acid,
X and X' independently represent the organic residue of
a polyol,
m represents the number of epoxy groups of the
polyepoxide ring opened with carboxylic acid groups,
n is an integer of from 1 to 7, and
p is a number of from 1 to 15.
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1 334606
In the preferred embodiments X-~OH)n
represents the structure
R"'
--tCH2-CH-o ~ H
and X' represents the structure
R"' R"'
t CH2-1H-o )y 1 CH2-1H-
where R"' represents hydrogen (-H) or methyl (-CH3), and
y is a number of from 4 to 25. In the most preferred
embodiments, m is 2 or 3 and most preferably 2, and p is
from 1 to 7.
The polyesters of the formula (i) are made in a
manner similar to that described in U.S. Patent
4,403,093. In the first step, a cyclic dicarboxylic acid
anhydride is reacted with a polyol (preferably a
polyoxyethylene or polyoxypropylene glycol having a
15 molecular weight of from about 200 to about 1500) under
conditions sufficient to form a half-ester with
substantially no polyesterification product. The
resultant half-ester is then reacted with a polyepoxide
under conditions to form the resultant polyester.
In preparing the formula (i) polyesters, a
cyclic l,2-dicarboxylic acid anhydride is reacted with a
polyol under conditions sufficient to ring open the
anhydride, forming the half-ester with substantially no
polyesterification occurring (i.e., both carboxyl groups
25 f the anhydride esterified by polyol in a recurring
manner).
In bringing an anhydride and a polyol together
under suitable reaction conditions, reaction can occur in
at least two ways. The desired reaction mode involves
30 opening the anhydride ring with hydroxyl, i.e.,
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!:
-- C --C I ~!
\ - C - C - OR
O + HOR > ¦C - C - C - C - OH
O l O
Alternately, carboxyl groups formed by opening
of the anhydride ring can react with hydroxyl groups to
give off water. The latter reaction is not desired
since it can lead to polycondensation reactions
resulting in products with broad molecular weight
distributions.
To achieve reaction, the anhydride and polyol
are contacted together, usually by mixing the two
ingredients together in a reaction vessel. Preferably,
the reaction is conducted in the presence of an inert
atmosphere such as nitrogen.
For the desired ring-opening and half-ester
formation reaction, a cyclic 1,2-dicarboxylic acid
anhydride is used. Reaction of a polyol with a
carboxylic acid instead of an anhydride would require
esterification by condensation to eliminate water which
would have to be removed by distillation which, under
these conditions, would promote undesired polyester-
ification.
The reaction temperature is preferably low,that is, no greater than 160C and usually within the
range of 60C to 160C, and preferably from 100C to
140C. Temperatures greater than 160C are undesirable
because they promote polyesterification, whereas
temperatures less than 60C are undesirable because of
sluggish reaction.
The time of the reaction can ~Jary depending
upon the temperature of reaction. Usually, the reaction
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time will be from as low as 10 minutes to as high as 24
hours.
The molar ratio of anhydride to polyol is
usually from about 0.5 to 1.5:1, and is preferably about
5 1:1 to obtain a maximum conversion with maximum purity.
Ratios less than 0.5:1 are undesirable because they
result in unreacted polyol. Ratios greater than 1.5:1
are not preferred because of increased formation of high
molecular weight polyesters.
Among the cyclic anhydrides which can be used
in the practice of the invention are those which,
exclusive of carbon atoms in the anhydride moiety,
contain from about 2 to 30 carbon atoms. Substituted
cyclic anhydrides can also be used provided the
15 substituents do not adversely affect the reactivity of
the anhydride or the properties of the resultant
polyester. Examples of substituents would be chloro and
alkoxy. Examples of anhydrides include maleic
anhydride, succinic anhydride, glutaric anhydride,
20 phthalic anhydride, tetrahydrophthalic anhydride,
methyltetrahydroph~halic anhydride, hexahydrophthalic
anhydride, methylhexahydrophthalic anhydride,
tetrachlorophthalic anhydride, endomethylene
tetrahydrophthalic anhydride, and chlorendic anhydride.
The polyols used to prepare the half-ester are
preferably polyoxyethylene or polypropylene glycols
having molecular weight of from about 200 to about 1500,
and preferably from about 200 to about 1000. However,
substantially any polyol may be used. Among the polyols
30 which can be used are those which contain from about 2
to 20 carbon atoms. Preferred are aliphatic polyols,
particularly aliphatic diols or triols, most preferably
those containing from 2 to 10 carbon atoms. Examples
include ethylene glycol, 1,2-propanediol,
35 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol,
glycerol, 1,2,3-butanetriol, 1,6-hexanediol, neopentyl
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glycol, diethylene glycol, dipropylene glycol,
trimethylolpropane, 2,2,4-trimethylpentane-1,3-diol,
2,2-dimethyl-3-hydroxypropyl 2,2-dimethyl-3-hydroxy-
propionate, and 1,4-cyclohexanedimethanol. Preferred are
those aliphatic diols or triols selected from the class
consisting of neopentyl glycol, 2,2,4-trimethylpentane-
1,3-diol, 2,2-dimethyl-3-hydroxypropyl 2,2-dimethyl-3-
hydroxypropionate, diethylene glycol, dipropylene glycol,
1,6-hexanediol and trimethylolpropane. Higher
functionality polyols such as tetrols can be used but
they are not preferred. An example would be
1,2,3,4-butanetetrol. Alkoxylated products of such
polyols can also be used. In general, it is preferred
that the molecular weight of the polyol range from 62 to
2000, and preferably from about 200 to about 1000.
After the anhydride and polyol are reacted
together, the resultant half-ester is further reacted
with a polyepoxide to chain extend the half-ester to form
a liquid polyester oligomer. Chain extension occurs
through reaction of the carboxylic acid groups of the
half-ester with the epoxy groups of the polyepoxide.
Although the structure of the final product is not known
with certainty, the major product (i.e. greater than 50
percent by weight based on total weight) is believed to
be of the structure:
R -[0 -IC- R'-ICl O ~xtH)n]m
O O
where R, R', X, n and m are as defined earlier.
The half-ester and the polyepoxide are reacted
together by contacting under conditions sufficient to
form the polyester. Preferably, the half-ester and the
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1 334606
polyepoxide are reacted in the presence of an inert
atmosphere such as nitrogen.
The half-ester and polyepoxide can be contacted
together by simply mixing the two togeth~r. It is
preferred to add the polyepoxide to the half-ester
incrementally so as to better control the reaction and to
obtain higher yields of the desired liquid polyester
oligomer. The proportions of the half-ester and the
polyepoxide are such that the equivalent ratio of epoxy
to carboxylic acid is from about 1:1 to 2.5:1. To obtain
maximum conversion to the desired polyester, the
equivalent ratio of epoxy to carboxylic acid is chosen so
that the acid number is reduced to acceptable low value
(e.g., less than 2.0). A preferred ratio is from 1:1 to
1.10:1, and is most preferably about 1.05:1. Ratios less
than 1:1 result in less than the optimum amount of
product, whereas ratios greater than 1.1:1 may result in
unreacted epoxy, which is undesirable.
The temperature of reaction should be less than
220C and usually within the range of about 60C to
220C, and preferably 140C or less. Temperatures higher
than 140C are generally undesirable because of
competition between the hydroxyl groups and epoxy groups
for reaction with carboxyl groups and between hydroxyl
groups and carboxyl groups for reaction with epoxy
groups, resulting in undesirable polyesterification
reactions. Reaction temperatures less than 60 C are
undesirable because of sluggish reaction.
Further a catalyst (such as organophosphine) is
preferably used. Examples of suitable catalyst of this
include triarylphosphines such as triphenylphosphine.
Examples of other catalysts include amines such as
triethylamine and inorganic bases such as potassium
hydroxide. When catalyst is used, it is used in amounts
of about 0.1 to 2 percent by weight, based on total
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weight of the reactants. The presently preferred
catalyst is one sold as Cordova Accelerator A~C-2,
available from Cordova Chemical Company and belie~Jed to
be a chromium octoate.
The time of reaction depends on how tne
reactants are contacted, the temperature of reaction and
the presence or absence of catalyst. In general,
reaction times will vary from about 30 minutes to 24
hours.
The polyepoxides which are used are those
having 1,2-epoxy equivalency greater than 1, preferably
2 and up to about 3Ø Higher functionality
polyepoxides, i.e., greater than 3, are not preferred
because of considerable chain branching and gelation
15 problems. The preferred polyepoxides are polyglycidyl
ethers of polyhydric phenols such as bisphenol A. These
polyepoxides can be produced by etherification of a
polyhydric phenol with an epichlorohydrin such as
epichlorohydrin in the presence of an alkali. Examples
20 of polyphenols other than bisphenol A are halogenated
bisphenol A; 1,1-bis-(4-hydroxyphenyl)ethane;
2-methyl-1,1-bis-(4-hydroxyphenyl)propane;
2,2-bis-(4-hydroxy-3-tertiarybutylphenyl)propane;
bis-(2-hydroxynaphthyl)methane; 1,5-dihydroxy-
25 naphthalene; and the like. While polyhydric phenols arepreferred, other cyclic polyols can be used.
Cycloaliphatic polyols such as 1,2-cyclohexanediol,
1,4-cyclohexanediol, 1,2-bis-(hydroxymethyl)-cyclo-
hexane, and hydrogenated bisphenol A, can be used.
Polyglycidyl ethers of polyhydric alcohols such
as ethylene glycol, diethylene glycol, 1,2-propylene
glycol, and 1,4-butylene glycol can also be used.
Polyglycidyl esters of polycarboxylic acids
which are produced by the reaction of epichlorohydrin or
35 a similar epoxy compound with an aliphatic or aromatic
polycarboxylic acid can also be used. Examples of
Mo-2984 - 8 -
1 334~05
polycarboxylic acids are dicarboxylic acids such as
adipic acid, succinic acid, glutaric acid, terephthalic
acid, dimerized linoleic acid and the like.
Also useful as the polyester polyol are those
having the idealized structure
O Q
Il 11
H--O-X ' -O-C-R"-C p O--X ' -OH
where R" represents the residue of an aromatic anhydride
or aromatic dicarboxylic acid and X' represents the
organic residue of a polyol, and p is a number of from
from 1 to 15. Such polyester polyols are prepared by
reacting an aromatic anhydride or acid with a dihydroxy
material. Suitable diols are those of the type mentioned
relative to preparation of the formula (i) polyesters.
Similarly, the anhydrides usable are those aromatic
anhydrides described or useful in the preparation of the
formula (i) polyesters. Acids such as isophthalic and
terephthalic acids, as well as dimethyl esters of these
acids produced via transesterification, are also useful.
The polyesters of formula (ii) are produced by
art recognized techniques.
The polyesters of the present invention are
liquid and are eminently suitable for use in a reaction
injection molding process (RIM) to produce parts having
excellent flame properties. As is known, the RIM process
is a filling technique in which the highly active, liquid
components are rapidly injected into a closed mold.
Substantially any of the isocyanates, chain extenders,
and cross-linkers known in the art can be used in
addition to the polyesters described herein.
The invention is further illustrated but is not
intended to be limited by the following examples, in
which all parts and percentages are by weight unless
otherwise specified.
M~-2984 ~9~
EXA~LES 1 334606
Example 1
4850 parts of a polyoxyethylene glycol of about
400 molecular weight were added to a 12 liter flask.
5 1796 parts of phthalic anhydride were added over a
period of about 15 minutes. The flask was heated to
130C and held at that temperature for 1 1/2 hours.
About 81 parts of AMC-2 (an accelerator available from
Cordova Chemical Company and believed to be a chromium
10 octoate) were then added. 2377 parts of Epon 828 (a
liquid bisphenol-A e'poxy resin available from Shell
Chemical Company, having a maximum Gardner Color of 4, a
viscosity at 25C of 100-160 poises and a weight per
epoxide of 185-192) were then added and the reaction
15 mixture was held at'130C for 1 1/2 hours. The
resultant product had an OH number of 149 and an acid
number of 0.1.
Example 2
4950 parts of CarbowaX 600 (a polyoxyethylene
20 glycol of about,600 molecular weight) were added to a
flask. Over a period of about one hour, about 1222
parts of phthalic anhydride were added, during which
time the temperature gradually rose to 110C. After
another ten minutes, the temperature had risen to 130C.
25 The temperature was held at 130C for 2 1/2 hours. 62
parts of- AMC-2-were then added. About 1540 parts of
Epo~ 828 were then added over a period of about 15
minutes. The temperature was held at about 125C for
about one hour. An additional 57 parts of Epon*828 were
30 then added and the temperature was held at 125C for
2 1/2 hours. Heating was stopped and the product,
having an OH number of 118 and an acid number of 0.1,
was stored at room temperature.
Example 3
2800 parts of Carbowax 200 (a polyethylene
glycol of 200 molecular weight) were weighed into a
Mo-2984 - 10 -
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1 334606
- flask and heated to 80C. Over a period of about 20
minutes, 2074 parts of phthalic anhydride were added.
The temperature gradually rose during the addition, and
after a total time of about 50 minutes, reached a
5 temperature of 145C. The temperature was then
maintained at 130C for about 5 hours. 49 parts of
AMC-2 were then added. About 2437 parts of Epon 828
were added over a period of about 55 minutes, after
which time, the temperature had reached 165C. The
10 temperature was then adjusted to 130C. After about 8
hours, 203 parts of Epon 828 were added, and the
temperature was kept at 130C for another 5 hours. 107
parts of Epon*828 were then added and the temperature
was kept at 130C for another 5 hours, after which time
15 the product was cooled to room temperature. The product
had an OH number of 187 and an acid number of 2.2.
Example 4
A 12 liter, 3 neck flask was charged with 4506
parts of Carbowa~ 400 (a polyoxyethylene glycol of 400
20 molecular weight) and heated to 100C with stirring.
2028 parts of resin 565 (the diether of propylene glycol
and bisphenol-A) and 4.8 parts of Fascat 4102 (butyltin
tricarboxylate available from M~T) were then added.
Phthalic anhydride (1668 parts) was then added over a
25 period of about 10 minutes. The ~emperature was then
raised to 210C and held at that temperature for about
9 1/2 hours with removal of water. The resultant
product had an OH number of 77 and an acid number of
0.3.
30 Example 5
A 12 liter, 3 neck flask was charged with 5600
parts of Carbowax*200 and heated to 100C with stirring.
2962 parts of phthalic anhydride and 5 parts of Fascat*
4102 were then added and the temperature was raised to
35 210C. The temperature was maintained at 210C for
about 7 hours with removal of water. The resultant
Mo-2984 - 11 -
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1 334606
product had an OH number of 100 and an acid number of
0.2.
Example 6
A 12 liter! 3 neck flask was charged with 5195
S parts of Carbowax 200 and heated to 120C. 3193 parts
of phthalic anhydride and 2.1 parts of Fascat ~102 were
then added. The temperature was raised to 210C, ~nd
held at that temperature for about 14 hours with removal
of water. The resultant product had an O~. number of 60
- 10 and an acid number of 1.0
Examples 7 through 18
In these examples various parts were made via
the RIM process. The components used were as follows:
POLYOL A - a glycerine-initiated polypropylene oxide
15 product having an OH number of about 1050.
POLYOL B - a glycerine initiated polypropylene oxide
product having an OH number of about 28, and having
ethylene oxide tips.
EG - Ethylene Glycol
20 ADDITIVE A - a quaternary ammonium salt of tall oil and
the amide prepared from tall oil and N,N-dimethyl-1,3-
propane diamine.
~C 193 - a silicone surfactant commercially available
~from Dow Corning.
25 PC 8 - Polycat--8 - N,N-dimethylcyclohexylamine,
available-from Air Products.
T-12 - dibutyl tin dilaurate.
AB 19 - Antiblaze l9, a cvclic phosphate ester flame
retardant available from Albri~ht & Wilson Americas Inc.
30 Iso - a 50/50 blend of Mondur*PF and Mondur MR*(two
commercially available isocyanates from Miles Inc.)
-~ having an isocyanate group content of
about 27~.
The components and the amounts thereof were as
35 indicated in Table I.
~o-2984 - 12 -
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1 334606
RIM plaques were prepared using a laboratory
piston metering unit and clamping unit. The metering
unit was a two component instrument having a maximum
metering capacity of 0.6 liters. A rectangular mold,
5 300 mm x 200 mm x 8 mm, was used to mold the samples
under the following conditions:
Component A Temp 32C
Component B Temp 40C
Isocyanate Index 110
10 A/B Weight Rates (125-140)/100
Mold temperature 60C
Impingement Pressure 2646 psi
External Mold Release Agent Silicone spray
designated MR 515,
available from
Chemtrend
Demold time 2 minutes
No post cure.
Various physical properties and flame
20 properties were tested, with the results as set forth in
Table I. Example 7 was a comparative test.
Mo-2984 - 13 -
1 334606
o
o ,,
f O 1
O ~1
O
O
O ~1
O
O ~1
O
O C~
O I I I u~ ~i 0 ,~
O
C`~ r--
o
CQ ~ t
g
~ ~ O O O O O O
P~ O O O O O O O O .,
o o c~ o o ~o o po~ o ~
Mo-2984 - 14 -
,f~';~L
1 334606
g C~
o
'~ o~ ' .J r-- O H E~
~ co ,~ ~ z c~
c~i o
r~ C~l ~ ^ ~ o o~
co ~ ~; ~ o ~ o c~
~D r1 C~ CO r1 r~ :~
o
~ g ~ C~
o ,~cr~ ^ o cq
rl ~ . CJ~ O U~ O
CCOj CiO O O C~r~
~_ O
O
v cr coco ^co O
C`~o ~ O
C~ ~o C~l ~ I` r~ ~ o
H O
g~ a~
U~ CS` ^ o U~
Cl~ o r~ ~J C~l O
J cr ,~
o
o u~ c)
c~ c~l 1~ c~l O
or~ o ~D ~
rl
.,~
,~ o. v
~q
r H r
V ~ ~ ~C `~.
~ ~ r -`
C ~ ~-- G
:~ n o c~
r~ C~
~ C~ p~,C
C i~ ~ O
v
U~
C~l O CO C~l CO CO
~: a c~
Mo-2984 - 15 -
TABLE I (Cont'd)
ASTM Test Example 13 14 15 16 17 18
D 792 Density, pcf 70~0 68.8 70.0 67.5 71.4 69.4
D256 Charpy Impact ft-lb/in2 13.49 5.05 17.58 18.88 19.27 13.60
D 790 Flex. Mod. @ RT, psi 395,000 410,000 390,000 3Y5,000 405,000 394,000
Heat Distortion
D 648 C (60 psi~ 93.9 74 88 66.1 96.5 70.5
Radiant Panel Test
E 162 (Flame Spread Index) 110 119 103 133 215 124
D 638 Tensi]e, psi lQ200 3100 9125 9550 10200 8950
~, D 638 Elongation, /O 5 2 2 4 8 5
a~ ~1
I Flammability 30 sec 30 sec 32 sec 28 sec 23 sec 38 sec
UL 94 V-0 V-0 V-0 V-0 V-O V-0 ~
o
1 334hO6
Although the invention has been described in
detail in the foregoing for the purpose of illustration,
it is to be understood that such detail is solely for
that purpose and that variations can be made therein by
those skilled in the art without departing from the
spirit and scope of the invention except as it may be
limited by the claims.
Mo-2q84 - 17 -
