The reaction perfluorinated hydroxyl terminated polyether with diisocyanate to form polyurethane is discussed. Data are given on the resin's oxidation stability, chemical resistance, and low temperature flexibility

Rochow, S. E.

Stump, E. C., Jr.

English

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ATTN OF: GP
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
WASHINGTON. D.C. 20546
(UASA-Case-NPO-1076 7-1). HIGHLY
FLUOBINATBD POLYUBETHANES Patent
(Peninsular ChemHesearch, Inc.) H p
N73-33076
TOt
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United States Patent
Fletcher et al.
[in 3,755,265
[45] Aug. 28, 1973
[ 54] HIGHLY FLUORINATED POLYURETHANES
[76] Inventors: James C. Fletcher, Administrator of
the National Aeronautics and Space
Administration with respect to an
Invention of; Eugene C. Stump,
Gainesville, Fla.; Stephen Eugene
Rochow, Ann Arbor, Mich.
[22] Filed: Apr. 4, 1972
[21] Appl. No.: 241,061
Related U.S. Application Data
[63] Continuation-in-part of Ser. No. 770,417, Oct. 24,
1968,abandoned.
[52] U.S. Cl 260/77.5 AP
[51 ] Int. Cl C08g 22/14
[58] Field of Search 260/77.5 AP
[56] References Cited
UNITED STATES PATENTS
3,574,770 4/1971 Paine 260/77.5 AP
Primary Examiner—Donald E. Czaja
Assistant Examiner—M. J. Welsh
Attorney—John R. Manning. Monte F. Mott and
Wilfred Grifka
[57] ABSTRACT
Polyurethanes having the repeating unit:
T o o -|
-|-CH!(CF(CFi)O(CFi)pOCF(CFj)]nCHiOCNHRNHCO-j-
where
n is an integer of 1 to 12,
p is an integer of 2 to 23,
y is an integer of 1 to 1000, and
R is any radical suitable to link isocyanate groups
and is preferably selected from the group
consisting of alkylene and halogen substituted
alkylene radicals of four to 12 C atoms, substituted
and unsubstituted phenylene groups of up to 20 C
atoms.
7 Claims, No Drawings
3,755,265
HIGHLY FLUORINATED POLYURETHANES
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of U.S. ap-
plication Ser. No. 770,417 filed Oct. 24, 1968, now 5
abandoned.
Other objects will be apparent from the following de-
tailed description and examples.
BRIEF SUMMARY OF THE INVENTION
This invention relates to new polyurethanes having
the formula:
ORIGIN OF THE INVENTION
The invention described herein was made in the per-
formance of work under a NASA contract and is sub-
ject to the provisions of Section 305 of the National
Aeronautics and Space Act of 1958, Public Law
83-568 (72 Slat. 435; 42 USC 2457).
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is in the field of polymers. More partic-
ularly, the invention relates to new highly fluorinated
polyurethane polymers.
2. Description of the Prior Art
Polyurethane resins, also known as isocyanate resins,
are a well known class of synthetic polymers. They may
be either thermoplastic or thermosetting. The polyure-
thane resins are made into flexible or rigid foams and
flexible and stiff fibers. They are also utilized as coat-
ings, linings, and as elastomers. The polymer units are
formed from the reaction of a diisocyanate with a diol.
Polyethers have been the most important source of hy-
droxyl groups. One of the most popular polyethers uti-
lized is polyoxypropylene. Toluene diisocyanate and
diphenylmethane-4,4'diisocyanate are two of the more
prevalent diisocyanates reacted to form the polyure-
thane resins. ;
In the herein invention, a perfluorinated hydroxy ter-
minated polyether having the general formula
HOCH2[CF(CF3)O(CF2)BOCF(CF3)]BCH2OH
where n is an integer of 1 to 12,
and p is an integer of 2 to 23
is reacted with a diisocyanate to form the polyurethane.
In U.S. Pat. No. 3,250,807, there is disclosed the basic
monomeric ether structure utilized. However, the pa-
tent discloses the ether terminated with acid or acid flu-
oride groupings rather than hydroxyl groupings. In. U.
S. Pat. No. 3,637,842 of Jan. 25, 1972, there is dis-
closed a method of polymerizing the ethers disclosed in
the aforementioned patent such that n is equal to at
least 2 to 12. Additionally, the copending application
further discloses converting the acid fluoride termi-
nated polyethers to hydroxy terminated ones. It is these
hydroxy terminated perfluoropolyethers that are con-
templated as the starting materials utilized herein.
Though, as indicated, there are several polyurethane
resins available on the commercial market, none would
possess the same thermal properties, non-flammability
and the like, of polyurethanes using perfluorinated
ethers.
OBJECTS OF THE INVENTION
An object of this invention is to provide new polyure-
thane resins having improved oxidative stability.
Another object of this invention is to provide new
polyurethane resins having outstanding chemical resis-
tance and low temperature flexibility.
A further object of this invention is to provide highly
fluorinated polyurethanes.
F °
-LcHi[CF(CFi)0(CF))pOCF(CFi)]BCHiOCNHRNHeO-j-
l— _Jr
o n\ I
10
where
n is an integer of 1 to 12,
p is an integer of 2 to 23,
y is an integer of 1 to 1000, and
IS R is any radical suitable to link isocyanate groups and
is preferably selected from the group consisting of
alkylene and halogen substituted alkylene radicals
of four to 12 C atoms, substituted and unsubsti-
tuted phenylene groups of up to 20 C atoms.
20 The polyurethane results from the reaction of a diol
having the formula HOCH2[CF(CF3)O(CF2.
)pOCF(CF3)]nCH2OH, where p and n are as defined
above, with a suitable diisocyanate such as tetrafluoro-
m-phenylene diisocyanate. The formation of the final
25 polyurethane product merely involves heating the two
reactants over a wide temperature range for varying
lengths of time to obtain products having different
properties of hardness, strength and the like. The resul-
tant polyurethanes can be used for films, sheets, seals,
30
 and many other applications where good chemical re-
sistance, low temperature flexibility and non-flamma-
bility is desired. It is believed the invention will be fur-
ther understood from the following detailed description
and examples.
35
40
DESCRIPTION OF PREFERRED EMBODIMENTS
As indicated, the starting diol prepolymer material
utilized to form the polyurethanes of this invention hav-
ing the general formula
L
45
50
55
-j-CH,[CF(CFi)0(CF,)pOCF(CFOJ.CH)OCNHENHCO-|-
L _Jr
where
n is an integer of 1 to 12,
p is an integer of 2 to 23,
y is an integer of 1 to 1000, and
R is any radical suitable to link isocyanate groups and
is preferably selected from the group consisting of
alkylene and halogen substituted alkylene radicals
of four to 12 C atoms, substituted and unsubsti-
tuted phenylene groups of up to 20 C atoms, is dis-
closed in the above-mentioned U.S. Pat. No.
3,637,842. Briefly, these diols are derived from an
acid fluoride terminated corresponding perfluoro-
ether which has first been polymerized and then re-
duced to change the terminal groups from acid flu-
oride to hydroxyl. As indicated in the co-pending
application, it is preferable that the diols have a
molecular weight range of about 1500 to 2000 to
provide ease of handling and to produce satisfac-
tory end products.
The diisocyanate utilized has the general formula:
OCNRNCO where R is as defined in the above gen-
eral formula for products of this invention. The halogen
substitutions are generally either chlorine or fluorine
atoms. The substituted phenylene groups include halo-
3,755,265
gen substitutions, alkyl, aryl and alkaryl groups. To
practice this invention, any diisocyanate previously and
conventionally utilized to produce polyurethane resins
is contemplated. Examples of conventional diisocya-
nates include toluene diisocyanate, including mixtures 5
of its isomers such as the 2,4 and 2,6 isomer, di-
phenylmethane-4, 4'-diisocyanate and hexamethylene
diisocyanate.
Particularly, it is desirable in the herein invention to
utilize diisocyanates containing a maximum amount of 10
fluorine atoms. The extremely good chemical resis-
tance, non-flammability and the like can be attribut-
able to the presence of fluorine atoms in the polymer
chain. This, if the diisocyanate also contains a high sub-
stitution of fluorine atoms like the diol utilized, one ob- 15
tains a polymer containing the desired content of fluo-
rine. Thus, it is preferred to utilize diisocyanates such
as tetrafluoro-m-phenylene diisocyanate, tetrafluoro-p-
phenylene diisocyanate, and the like.
The resultant polymers of this invention will range 20
from sticky semi-solids to tough brittle sheets, depend-
ing upon the amount of diisocyanate utilized in the ex-
tension and cross linking reaction that transpires be-
tween it and the diols. It should be noted that although
the hardness of the resultant polymers increases with 25
increasing ratio of diisocyanate to diol, the glass tem-
perature of the resultant polyurethanes is not adversely
affected. Thus, it is contemplated to utilize a mole ratio
of diisocyanate to diol of from 1:1 up to about 3:1. The
preferred mole ratio range of the diisocyanate to diol 30
is between 1:1 and 2:1.
The time and temperature of the polymerization re-
action is dependent upon the molecular weight of the
prepolymer and the type of diisocyanate used. Comple-
tion of the polymerization for the given diol and diiso- 35
cyanate can be determined by the increase in viscosity
of the melt polymer. Generally, the temperature of cur-
ing can vary from 25° to 100°C, while the time of the
cure can range from 10 to 30 minutes.
the good thermal, oxidative, and chemical resistance
properties of other known highly fluorinated materials
such as Teflon, which is tetrafluorethylene, yet are elas-
tomeric materials and can be utilized as expulsion blad-
der materials, seals, gaskets, coatings and other similar
application.
It is believed the invention will be better understood
from the following detailed examples:
EXAMPLE I
A hydroxy terminated perfluoro polyether having the
formula HOCHZ[CF(CF3)O(CF,)SOCF(CF3)].CH2OH
and prepared in accord with the method described in
the above mentioned U.S. Pat. No. 3,637,842 was uti-
lized. This prepolymer had a molecular weight of about
1500. 10.5 grams or .0068 moles of the polyether was
added together with 2.35 grams or .0101 mole of
tetrafluoro-m-phenylene diisocyanate to a 100 ml.
resin kettle equipped with a stirrer, N2 inlet and outlet.
The diisocyanate was previously prepared in accord
with the procedure set forth by R. Gosnell and J. Hol-
lander in the Journal of Macromolecular Science
(Physics) Bl(4), 831 (1967). After 20 minutes of stir-
ring at room temperature, the reactants had balled
about the stirrer. The material was then removed and
placed in a press between 10 mil shims at 3000 psi and
160°C for Vfe hour. This produced a yellow, flexible
sheet of the resultant polymer. The glass transition tem-
perature was — 80°C and the Shore A hardness was 79.
The above was repeated varying the amounts of pre-
polymer and diisocyanates as well as the temperature
and time of heating. Hydroxy terminated per-
fluoropolyether prepolymer of varying molecular
weights ranging from 1500 to 2193 was utilized. The
results of the various preparations indicating the glass
transition temperature Tg and the Shore A hardness,
together with an indication as to the type of product,
are indicated in the following table:
TABLE I
Polyurethanes from HOCU![CF(CF3)O(CFi)sOCF(CFj))nCH!OH and Tetrafluoro-m-phenylene Diisocyanate
Pre-
polymer
Exp. No. M. wt.
160.1
160.2
1603
160.4
160.5
1606
160.7
160.8
160.9
160.10 ...
2,193
2,193
2,193
,500
.500
,500
,500
,500
,500
,500
Mole ratio
Grams Grams diiso-
pre- diiso- cyanate/
polymer cyanate prepolymer
10.63
11.7
10.6
11.35
9.90
10.1
9.05
11.25
10.15
10.0
2.24
1.24
3.43
4.17
1.82
1.56
2.10
2.09
2.35
3.09
2/1
1/1
3/1
2.38/1
1.2/1
1/1
1.5/1
1.2/1
1.5/1
2/1
Temp.,
° C.
150
140
140
50-70
55-80
39
25-30
25-30
25-30
25-30
Glass
temper-
Time ature
(min.) Tg (° C.)
90
180 --.
120
30
10
20
10
-73 ,--
—5
-16
-80
-79
Hard-
ness b
59
62
79
90
Remarks
Brown, flexible film.
Sticky, semi-solid.
Weak, elastomeric film.
Brittle, yellow, slightly flexible sheet.
Weak, elastomeric solid.
Yellow, elastomeric film, decomposes at 234'. •
Yellow, elastomeric sheet.
Do.
Yellow, flexible sheet.
Yellow slightly flexible sheet.
• By differential scanning calorimeter.b
 Shore A.
It can be appreciated that the end groups of the poly-
mers of this invention are not readily determined. The
polymers can be hydroxy or isocyanate terminations,
' depending upon the stoichiometry of the reaction, re-
action conditions, and the like. Further, since the resul-
tant higher polyurethanes formed are infusible, one
cannot determine their molecular weight through avail-
able techniques. Thus, a practical upper limit of y =
1000 is given in the general formula for the products,
though the infusible polymers resulting could well have
a weight significantly less than that.
As can be seen, the polymers of this invention pro-
vide highly fluorinated structures which have many of
60
Though the materials prepared in the foregoing table
were all pressed to form sheets of the polymer of this
invention, it should be understood that the material can
be formed into various other shapes such as seals, hoses
and various forms of coatings.
What is claimed is:
1. Polyurethanes having the repeating unit:
65 I oCH,[CF(CFi)0(CF,)0OCF(CFi)],CH,OCiNHRNH(!oaO
J,
where
n is an integer of 1 to 12,
3,755,265
p is an integer of 2 to 23,
y is an integer of I to 1000, and
R is any radical suitable for linking isocyanate
groups.
2. The polyurethane of claim 1 where R is selected
from the group consisting of alkylene and halogen sub-
stituted alkylene groups of four to 12 C atoms, substi-
tuted and unsubstituted phenylene groups of up to 20
C atoms.
3. A polyurethane formed from the reaction at a 1:1
to 3:1 mole ratio of a diisocyanate with a diol having
the formula:
HOCH2[CF(CF3)0(CF2)pOCF(CF3)]nCH2OH
where
n is from I to 12 and
p is from 2 to 23.
10
15
4. The polyurethane of claim 3 where the mole ratio
of diisocyanate to diol is from 1:1 to 2:1 .
5. The polyurethane of claim 3 where the diisocya-
nate has the general formula:
OCNRNCO, where
R is selected from the group consisting of alkylene
and halogen substituted alkylene groups of four to
12 C atoms, substituted and unsubstituted phenyl-
ene groups of up to 20 C atoms.
6. The polyurethane of claim 3 wherein the diisocya-
nate is selected from the class consisting of tetrafluoro-
m-phenylene diisocyanate and tetrafluoro-p-phenylene
diisocyanate.
7. The polyurethane of claim 3, where p = 5.
20
25
30
35
40
45
50
55
60
65


Highly fluorinated polyurethanes

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