Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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sACKGROUND OF THE INVENTION
It has been known that polyester and
polyesterimi~e resins synthesized from acids, di~unctional
alcohols, and higher poly-functional alcohols are
particularly use~ul as an insulating coating for
electrical wires. An noted in U.S. Patent No. 2,936,296
- issued May 10, 1960 - Precopio et al, the insulating
material to be employed for these purposes must be able
to withstand extreme mechanical, chemical and electrical
stresses. More particularly, as increased currents are
passed through the ~ires extreme heating takes place
which will cause the insulation to break downO As is
noted in U.S. Patent No. 3,345,429 - issued October 3,
1967 - Sattler, the addition of higher poly-functional
alcohols ~e.g., those alcohols having three or more
hydro~yl groups) to the composition, results in the
polyester having a higher degree of thermal stability.
~owever, the poly-functional alcohols lack the flexibility
which is desired for insulated or enameled wires.
Therefore, in the past, synthetic resins were formed with
a mixture of both di-functional and higher polyfunctional
alcohols. Examples of the prior art include U.S. Patent
No 3,374,114 - issued March 19, 1968 - Wiener and U.S.
Patent No~ 3r378,402 - issued April 16, 1968 - Wiener,
U.S. Patent No. 3,449,467 - issued June 10, 1969 - Winstra,
U.S. Patent No. 3,296,024 - issued January 3, 1967 -
Jordan et al, U.S. Patent No. 3,426,098 ~ issued February
4, 1969 - Meyer et al, and U.SO Patent No. 3l310,512 -
issued March 21r 1967 - Curtice. As can be determined from
the above cited patents, many attempts have been made to
synthesize a polyester or a polyesterimide resin coating
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composition having the requislte characteristics for the
wire coatings in electrical devices.
In order to determine whether the composition
has the required thermal stability and flexibility, the
resin is applied to copper wire and convenkional tests
are performed. These tests are discussed in U.S. Patent
No. 2,936,296 - issued May lO, 1960 - Precopio et al,
cited above~ More particularly, thermal stability is
measured by "cut through" temperature which is the
temperature at which electrical contact can be estahlished
between two coated wires. The coated wires are placed
perpendicular to each other, and a load oE l,000 grams is
placed at the intersection of the wires. ~ potential of
llO volts is applied to the end of each wire and a suitable
indicator such as a buzzer is connected to the circuit.
The temperature of the crossed wires is increased at the
rate of 3C per minute until the insulator coating softens
sufficiently so that electrical contact is made between the
tw,o wires thereby causing the buzzer to actuate. The
temperature at which this occurs is measured as the "cut
through" temperature~ Typical "cut through" temperatures
~or polyester or polyesterimide resins made from a
combination of di-functional and tri-functional alcohols
are in the range of 200~300C.
As was noted above, an increase in the percentage
of tri-functional alcohols verses di-functional alcohols will
increase the thermal stability of the coatin~ but will
substantially impair its flexibility. The flexibi,lity of a
resi,n coa1ing is determined by stretching the wire conductor
an additional 25% of it,s original lenyth and wrapping the
wlre around à mandrel. The wire is then studied under a
mic~roscope to determine if there are any imperfections in the
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enamel. The degree of lexibility is measured by determining
the smallest diameter mandrel which the wire may be wound
around withou-t exhibitlny imperfections. Conventional
mandrel diameters are measured in multiples of -the wire
diameter such that a 3X mandrel has a diameter three times
the diameter of -the wire being tested. It is necessary for
wires used in applications such as those noted-above to
have a flexibility of at least 25% elongation on a 3X mandrel.
Another important consideration in the formation
o~ a resin, is that the polyester of polyesterimide resin
be dissolvable in readily available, inexpensive solvents.
The solvents most often employed in the prior art were
acidic organic solvents such as cresol and cresylic acid.
However, when these types of solvents are employed, the
us~al fire and health hazards as well as the corrosive,
acidic effect on the environment, and the cost factor
associated with such organic solvents were inevitable
present. It was suggested in the U.S. Patent No. 3,310,512
- issued March 12, 1967 - Curtice, that a water solvent be
employed to obviate this problem. German Patent
Publication No. 1,036~426 ~8/14/1952) also suggests water
solvent to obviate health and fire hazards. Others have
suggested the use of glycol ethers or glycol esters.
However, as noted in the Curtice patent, unless some
di-functional alcohols are employed in the synthesis,
problems arise with regard to the flexibility and toughness
of the resin.
In contrast, U.S. Patent ~o. 3,342,780 - issued
September 19, 1967 - Meyer suggests the forma-tion of a
polyester coating made from -tris-2-hydroxyl-ethyl-isocyanurate,
a poly-functional alcohol. And U.S. Patent No. 3,426,098 -
issued February 4, 1969 - Meyer et al. makes the identical
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suggestion with respect to polyesterimides. In U.S. Patent
No. 3,342,780 - issued September 19, 1967 - Meyer, and in
U.S. Patent No. 3,426,098 - issued February 4, 1969 - Meyer,
an acidic organic solvent, cresylic acid, is used to
disperse the mixture. As noted above in U.S. Patent No.
3,310,512 - issued March 12, 1967 - Curtice, in general/
an organic solvent is required to be employed in the formation
of a resin in order to maintain acceptable characteristics
of the resulting resin. More particularly, water, the
safer and less expensive solvent, may be used only when
the synthesis includes some amounts of di-functional
alcohols.
Therefore, it is an object of the subject invention
to provide a new and improved polyes-ter or polyesterimide
composition wherein the alcohols are all higher poly-
functional alcohols. It is a further object of -the subject
invention to provide a polyester or polyesterimide
composition which is characterized by both flexibility and
high thermal stability. It is another object of -the subject
invention to provide a polyester of polyesterimide resin
which can be aispersed in a water or normally liquid
nonacidic organic solvent, and yet maintain high thermal
stability and flexibility.
DESCRIPTION OF THE INVENTION
According to the present invention, there is
provided a new and improved polyester or polyesterimide,
dispersed in a water or non-acidic organic solvent. The
polyesterimide resin is a combination of an acid having at
least two carboxyl groups and a tri-functional or higher
-functional alcohol. Alcohols which may be employed in
the synthesis are represented by the formula:
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OH
HO - R - O~
wherein R may represent any aromatic, alkyl, cyclo alkyl or
any combination thereof. X may be a fourth hydroxyl y,oup
or a hydrogen or any other radical. Typical examples of
suitable alcohols are glycerine, tri-methylol propane,
triethanol propane, tris-~2-hydroxylethyltisocyanurate or
any combination thereof. The tri-functional or higher
functional alcohol is combined with a carboxylic acid, which
can be a dibasic acid such as terephthalic, isophthalic
or adipic. The acid can also be a mi~ture containing a
dibasic acid and a tri-functional acid or even a tetra-
functional acid such as trimellitic acid, its anhydride.
In a preferred feature of the invention, the
polyester or polyesterimide will be prepared in the presence
of a monofunctional alcohol, especially preferably a
monoether of a glycol or a polyglycol, e.g~, a Cl-C6 ether
of a Cl-C6 aklylene glycol or Cl-C6 alkylene polyglycol,
ethylene glycol mono methyl ether or diethylene glycol
monomethyl ether or diethylene glycol mono n-butyl ether,
~o mixtures of any of the foregoing, and the like.
To improve the abrasion properties of the
polyesterimide, small amounts of metal additives are employed.
A typical metal additive is tetra-isopropyl titanate. The
poly-functional alcohol, the acid and a metal additive are
combine.s and heated. The poly-functional alcohol will
genexally have a small percentage of water which should be
distilled off during heatlng. When the mixture reaches a
suitable acid number, e.~., below about 100, pxeferably
helow about 60, it is cooled, whereupon a co-solvent such
as butanol may be added. Xt is desirable -to use a small
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amount of co-solvent to produce a more stable dispersion
of the polyester, or polyes-terimide, especially when the
primary solvent comprises water. Generally the co-solvent
can be added prior to, during, or after neutralization. To
this mixture an amine, preferahly a tertiary amine, such as
dimethylethanolamine, is added to neutralize the mixture.
Thereafter, water or a non-acidic organic solvent such as
glycol ether or a glycol ester, e.g., diethylene ~lycol
monomethyl ether, is added to obtain sufficient dispersability.
The viscosity and the percent solids of the mixture are
adjusted based on the particular application of the resin.
Rolyesters or polyesterimides synthesized according
to the subject invention will have increased thermal
stability and high flexibility. The cut-through temperature
of the polyesterimides of the subject i-nvention is in the
order o~ over 300C. The polyester or polyes-~erimide
enameled wire will pass a 2X flex test a~ter a 25% elongation.
In addition, since the resin is dispersed in a non-acidic
medium, health hazards, as ~ell as costs, are minimized.
DESCRIPTIO~ OF THE PREFERRED EMBODIMENTS
Examples of polyester and polyesterimide resins
synthesized in accordance with the subject invention is
giYen below. They do not limit the inventionn
-EX~U~LE 1
To make a water dispersed polyesterimide a
flask is charged with thé following: - gms.
Trimellitic anhydride 22~
~ethylenedianiline 116
Tris-~2-hydroxylethyltisocyanurate 222
Isophthalic acid 150
M-pyrol* 180
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Trimethylol propane 206
Tetraisopropyl titanate 18
* Also known a N-methyl pyrrolidone
The above contents are stirred and heated to a
maximum of 217C., while excess water is distilled in a
Dean Stark trap. Heating is continued until an acid number
o~ 35 is reached and then the contents are allowed to cool
to 170C., whereupon 153 grams of the co-sol~ent butanol
are slowly added. The mixture is then neutralized by the
addition of 145 grams of dimethylethanolamine. The mixture
is then dispersed with 1300 grams of water. The result is
a clear solution with a percent solids of 35% and a viscosity
o~ 25C. of 1643 centipoise.
The resulting enamel was applied in a 10 foot
electric tower and run at speeds of 3Z and 35 feet per
minute. Standard 18 AWG copper wire having an enamel
thickness of between 2~9 - 3.1 mils is tested.
Each run passes the flexibility test of 25%
elongation wrapped around a 2~ mandrel. In addition, each
run passes both the sudden snap test and the 70/30 alcohol/
toluene solvent resistance test. Cut-through ls measured
~t 353C. and 335C. for the 32 and 35 feet per minute runs,
respectively. The wire is subjected to the standard repeat
scrape tests using a knife edye and a 780 gram load. The
test results indicate high abrasion resistance with the 32
and the 35 feet per minute runs withstanding 52 and 62
scrapes, respectively.
EX~PLE 2
To make a water dispersed polyester a flas]~ is
charged with the ~ollowing:
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ms
Tris~2-hydroxyethyltisocyanurate 222
Isophthalic acid 150
Terephthalic acid 242
Trimethylolpropane 206
Tetraisopropyl titanate 18
M-pyrol 180
The contents are heated slowly with the evolution of water
to a maximum temperature of 212C., whlle excess water is
distilled into a Dean Stark trap~ Heating is continued
until an acid number of 35 is reached. The contents are
then cooled to 17QC. and 244.5 grams of a co-solvent,
n-butanol, is slowly added. The mixture is then
neutralized by the addition of 165 grams of
dimethylethanolamine. The mixture is then dispersed with
1450 grams of water. The resultant clear solution has a
percent solids of 28.13% and a viscosity at 25 C~ of 931 cs.
This enamel is applied at a maximum temperature
of 915 F. in a 10-foot electric tower at 55 ft/min. using
seven passes on 18 AWG copper wire. The following results
are obtained.
Flexibility, 25% 2x
Continuity (Breaks/200 ft.) 2
Sol~ent Resistance (70 alcohol/
30 toluene) Pass
Dissipation Factor (170 C.) 7.0
Cut Through C., 2000 ym 384
Heat Age (100 hrs. at 175 C.) lx
Heat Shock 0%-30 min. at 155 C. 2x
Dielectric Strenyth (kv) 10.3
Burnout OF'M (O~erload Figure of
~erit) 7.52
Repeat Scrape 61.2 avg.
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_X~MP~E 3
To make a glycol ether-dipersed polyester a
flask is charged with the following: gmg
Tris~2-hydroxyethyltisocyanurate 222
Isophthalic acid 150
Terephthalic acid 242
Trimethylolpropane 206
Tetraisopropyl titanate 18
M-pyrol 180
The contents are slowly heated with the evolution of water
to a maximum temperature of 207C., while excess water is
distilled into a Dean Stark trap. Heatin~ is continued
unt~l an acid number of 3I.7 is reached. The contents are
then cooled to 170C. and 153 grams of n-butanol, 571 grams
of diethylene glycol mono methyl ether, and 190 grams of
Solvesso 100 are added. The resultant clear solution has a
percent solids of 39.75% and a viscosity at 25C. of 978 cs.
This enamel is applied at a maximum temperature
of 90Q F. in a ten-foot electric tower at 45 ft./min. using
2Q seVen passes on 18 AWG copper wire. The following results
are obtained:
Flexibility/ 25% 2x
Continuity (Breaks/200 ft.~ 2
Solvent Resistance (50 Alcohol/
50 Toluenel Pass
Dissipation Factor (170 C.) 4.8
Cut Through C., 2000 g 415
Heat Shock 0~ - 30 min. at 155 C. 2X
Dielectric Strength (kv~ 8.9
Burnout OFM 7.64
Repeat Scrape 203.0 avg.
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The enamel is applied again in five passes (2.4
mil. build) with an amide-imide top coat, two passes (0.Ç
mil build). Maximum temperature 900 F. in a ten--foot
electric ~ower at 45 ft./min. on 18 AWG copper wire. The
following results are obtained.
Flexibility, 25~ 2x
Continuity (Breaks/200 ft.) 2
Solvent Resistance (50 Alcohol/50
Toluenel Pass
lU Dissipation Factor (I70 C) 5.2
Cut Through C., 2000 g 411
Heat Shock 0% - 30 min. at 155 C. 2x
Dielec-tric Strength (kv) 10.3
Burnout OFM 7.74
Repeat Scrape 153.4 av~.
EXAMPLE 4
To make a glycol ether dispersed polyesterimide
in the presence of a mono-unctional ether glycol a flask
is charged with the following: gms.
Trimellitic anhydride 224
Methylene dianiline 116
Tris~2-hydroxyethyl~isocyanurate 222
Isophthalic acid 150
Texephthalic acid 145
Trimethylolpropane 206
Tetraisopropyltitanate 18
Diethylene glycol mono n-butyl 180
ether
The contents are heated slowly with the evolution of
water to a maximum temperature of 215 C. The excess water
being distilled into a Dean Stark trap. Heating is
continued until an acid nur~er o~ 30 is reached. The contents
are then cooled to 180C. and 220g. o* Solvesso 100 is added.
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When -the batch has further cooled to 150 C. 660 g. of
diethylene glycol monomethyl ether is added. To this
solution is also added 57.2 g. blocked isocyanate (Mondur SH),
23.6g. tetraisopropyl titanate in 75 g. diethylene ylycol
monomethyl ether and 25 g. Solvesso 100, 585 g.
diethylene glycol monomethyl ether, and 195 g. Solvesso 100.
The resultant solution has a percent solids of 37.71~ and a
viscosity at 25C. of 1525 cs.
This enamel is applied to 18 AWG copper wire at a
maximum temperature of 900F. in a ten-foot electric tower at
40 ft./min. in fi~e passes 2.4 mil. build) with an amide~imide
top coat, two passes (0.6 mil. build). The following results
are obtained.
Flexibility, 25% 3x
Continuity (Breaks/200 ft.) 0
Solvent Resistance ~50 Alcohol/50
Toluene) Pass
Dissipation Factor (220 C.) 11.9
Cut Through C.I 2000 g. 368
Heat Shock 0~ - 30 min. at 200 C. 2x
Dielectric Strength ~kv~ 8.2
Repeat Scrape 195 avg.
The foregoing demons-trates that the present
i~vention proyides a new and improved polyester or
polyesterimide resin ha~ing increased thermal stability and
a high degree o~ flexibility. The polyester or
polyesterimide resins o~ the subject invention are synthesized
with alcohols which are highly polyfunctional. In addition,
the polyester or polyesterimide resins are dispersible in
water and/or non-acidic organic solvents and this therefore
reduces manufacturing costs, while minimizing safety hazards
durin~ synthesis and transportation.
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It is to be understood that changes may be made
in the par-ticular embodiments of the i.nvention in liyhk oE
the above teachings and that these will be within the full
scope oE the invention as de:Eined by the appended claims.
