Note: Descriptions are shown in the official language in which they were submitted.
~64643
This invention relates to a process for the production of
polycondensates containing imide groups by reacting polycarboxylic
acid anhydrides, formic acid and polyisocyanates, and to their
use for coating metals, preferably lacquering wires or for the
production of ~ilms and laminates.
It is known that polyimides and polyamide imides can be ob-
tained by reacting polyfunctional isocyanates with polycarboxylic
acid anhydrides (German Auslegeschrift 1,256,418 and French Patent
1,375,461).
These polymers are used, for example, as binders for anti-
corrosive and decorative lacquers as wire lacquering and as insu-
lating films by virtue of their thermal stability, their extreme
hardness coupled with high elasticity, by the complete absence of
thermoplasticity, by their extremely high resistance to solvents
and by their good adhesion to metals, especially aluminium. Unfor-
tunately, the strong natural colour of poly(amide)imides and the
inadequate covering power of pigmented one-coat lacquers produced
from them have proved to be disadvantageous in the field of deco-
rative coatings. Brilliant colours, ~specially white lacquer fi-
ni~hes, cannot be obtained. In addition, the gloss of the lac~uer
~inishes is only just adequate.
; Moreover, the extremely hi~h viscosity of the polymer solu-
tions obtained by the various known processes lS a considerable
disadvantage for wire lacquering. Accordingly, only solu- ~
tions having a low solids contant can be used without diffi- ;
culty for lacquering. This results in a high consumption of sol-
vents which is undesirable not only in regard to economy, but
also in regard to pollution. Reducing the viscosity by reducing
the size o~ the molecules of the polymers present in solution has
not proved to be practical, because a longer stoving time is
,
Le A 15 953 - 1 - ~
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,.", , .,,, . . , . . , ~
,
~ )646~3
required for building up the molecule to the sizes requlred for
good lacquers. In addition, a considerable part o~ the conden-
sation reaction, which otherwise takes place in solution, takes
place on the wire, so that the lacquer film is in greater danger
of being permeated by small gas bubbles. Therefore only relative
low lacquering rates are possible by using the polyamide imides
obtained by conventional processes. Accordingly, in cases where
poly(amide)imides are used for surface lacquering, difficulties
are always involved in adapting the stoving conditions of the
base lacquer to those of the surface lacquer.
It has now surprisingly been found that the disadvantages
referred to above can be obviated by using, for the production
of lacquers, imide-group containing polycondensates, preferably
poly(amide)imides, obtained by polycondensing polycarboxylic acid
anhydrides, polyisocyanates and formic acid.
Accordingly, the present i~ve~tion relates to a process
~or the production o~ polycondensation products linked by cyclic
imide groups, wherein at least one organic polyisocyanate or
masked polyisocyanate9 formic acid and at least one cyclic di-
carboxylic acid anhydride compound which, in addition to the
cyclic anhydride group, are substituted at least once b~ another
cyclic anhydride, carboxyl, ester or S03H-group, are polycon-
densed, optionally in a solvent, at temperatures in the range
from 0 to 450C~ ~
The invention also relat~s to the use of these imide-group- ~`
containing polycondensates for lacquering metals, especially
wires, ~or the production o~ ~ilms or laminates.
It has been ~ound that the condensation products containing
imide groups according to the invention are far more suitable
~or use as binders ~or metal coatings than conventional polyamide
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.. .. : ' , ,: . :
1~64643
imides. Lacquers produced from the polycondensates according to
the invention are distinctly lighter and show outstanding gloss
wlthout any deterioration in their mechanical properties. In addi-
tion, it is possible to produce lacquers having more brilliant
colours, and the colour retention of the coating under the effect
of thermal ageing is also better. In this connection, it was not
possible to detect any reduction in hardness, thermoplasticity,
- mechanical properties and adhesion to metals. Owing to the rela-
tively low viscosity of the polymers it is possible not only to
use lacquer solutions having a high solids content, but also, con-
trary to expectation, to obtain much higher lacquering rates than
is possible in the case of non-regulated polycond~nsates. Accor-
dingly, it is possible owing to this higher lacquering rate to
apply coatings to base lacquers o~ the type which are normally -~
; 15 unable to withstand the temperatures required for stoving poly
(amide)imide lacquer solutions. Accordingly, the selection o~ -
multi-layer lacquered based on polyvinyl acetals, poly~rethanes,
epoxide reqins, polyamides, polyamide phenolic re~ins or acrylo-
nitrile copolymers, may be provided with ~urface lacquers of poly-
amide imides or polyimides without detrimentally a~ecting the
necessary stoving process.
,
Starting components suitable ~or the inventive process are
aliphatic, cycloaliphatic, araliphatic9 aromatic and heterocyclic
polyisocyanate~ (cf. Annalen 562, pages 75 to 136), for example
ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexa-
methylene diisocyanate, 1,12-dodecane diisocyanate, cyclobutane-
1,3 diisocyanate, cyclohexane-1,3- and -1,4-diisocyanate and any ~ -
mixtures of these isomers, 1-isocyanato 3,3,5-trimethyl-5-isocya-
nato methyl cyclohexane (German Auslegeschri~t 1,202,785), 2,4-
and 2,6-hexahydro tolylene diisocyanate and any mixtures of these
~ ~ 3 -
.
}.. .. . . . .. ... ..
~0646~3
isomers, hexah~dro-1,3- and/or 1,4-phenylene diisocyanate, per-
hydro-2,4'- and/or -4,4~-diphenyl methane diisocy~ate, 1 J 3- and
1,4-phenylene dii~ocyanate, 2,4- and 2,6-tolylene diisocyanate
and any mixtures o~ these isomers, diphenyl methane-2,4~-
and/or -4,45-diisocyanate, naphthylene-1,5-diisocyanate,
triphenyl methane-4,4~,4"-triisocyanate, polyphenyl-poly-
methylene polyisocyanates of the type obtained by condensing
aniline with formaldehyde, followed by phosgenation, and
described in, for example, British Patent Specifications
874,430 and 848,671, perchlorinated aryl polyisocyanates of
the type dsscribed in, for example, German Auslegeschrift
1,157,601, polyisocyanates containing carbodiimide groups
of the type described in German Patent Specification
1,092,007, diisocyanates of the type described in US Patent
Specification 3,492,330, polyisocyanates containing allophanate
groups of the type described in, for example, British
Patent Specification 994,890~ Belgian Patent Specification
761,626 and published Dutch Patent Application 7,102~524,
polyisocyanates containing lsocyanurate groups of the type
described in, for example, German Patent Specifications
1,022,789; 1,222,067 and 1,027,394 and German Of~enlegungss-
chrifts 1,929,034 and 2,004,048, polyisocyanates containing
urethane groups of the type described in, for example,
Belgian Patent Specification 752,261 or US Patent `
Specification 3,394,164, polyisocyanates containing acylated
urea groups according to German Patent Specification 1,230,778,
polyisocyanates containing biuret groups of the type described
in, for example, German Patent SpeciIication 1,101,394, British
Patent Specification 889,050 and French Patent Specification
3 7,017,514, polyisocyanates produced by telomerisation reactions
Le A 15 953 _ 4 _
1~64~3
of the type described in, for examplc, Belgian Patent
Specification 7239640, polyisocyanates containing ester
groups of thc type described in, for example, British Patent
Specifications 956,474 and 1,072,956, US Patent Specification
3,567?763 and German Patent Specification 1,231,688 and
rcaction products of the above-mentioned isocyanates with
acetals accorfling to German Patent Specification 1~072,385.
It is also possible to use the distillation residues
containing isocyanate groups which accumulate during the
commercial production of isocyanates, optionally in solution
in one or more o~ the above-mentioned polyisocyanates.
Any mixtures of the above-mentioned polyisocyanates may
also be used.
Preferred polyisocyanates correspond to the general
formula:
R (-NC0)5
in ~hich R2 represents an optionally substituted alkyl
radical having 1 to 20 carbon atoms, an aryl radioal
having 5 to 12 carbon atoms, a cycloalkyl radical having 5
to 12 carbon atoms, an alkyl aryl radical having 6 to 20 ~: .
carbon atoms and an aryl or cycloalkyl radical having 5 to 12
carbon atoms con~aining hetero atoms such as N, 0 or S, and -
z is an integer from 2 to 4, preferably 2 or 3. ~ :
It is preierred to use the commercially readily
available mixtures of tolylene diisocyanates, m-phenylene
diisocyanate, also phosgenated condensates of aniline and ~ :
~ormaldehyde having a polyphenylene methylene structure and
the symmetrical compounds 4,4'-diisocyanato diphenyl methane,
4,4~-diisocyanato diphenyl ether, p-phe~ylene diisocyanate,
4,4~-diisocyanato diphenyl dimethyl methane, analogous
Le A 15 953 - 5 -
~06~643
hydroaromatic diisocyanates and allphatic diisocyanates ha~ing
2 to 6 carbon atom~, such as hexamethylene diisocyanate.
The isocyanates may be used in free form and also partly or
completely masked in the ~orm of their derivatives obtained by
reaction with compounds containing reactive hydrogen which can
be used as isocyanate donors under the reaction conditions.
Preferred donors~ masked isocyanates, are the carbamic acid
esters obtained from aromatic and aliphatic mono- and polyhydroxy
compounds which correspond, for example, to the general ~ormulae:
~2(NE-C-O~A)z and ~ -C-NH-R2-NH-C-0-B-0-
:' o O O
_ _ n
in which R2 and z are as de~ined above, A represents the organic
radical of a monohydroxy compouncl and B the organic radical o~ a ~
bis- or tris-functional hydroxy compound9 preferably an alkyl ra- ~ -
dical having 1 to 10 carbon atoms, a cycloalkyl radical havlng
5 to 10 carbon atoms, an alkyl aryl radical having 7 to 12 carbon
atoms or an aryl radical having 6 to 12 carbon atoms, n is an in-
teger from l to looo pre~erably l to 500~. The radioals may also be
substituted.
` Examples of carbamic acid esters of this kind are the carb-
amic esters of phenol, isomeric cresols, their commercial-grade
mixtures and similar aromatic hydroxyl compounds, aliphatic mono-
alcohols such as methanol, ethanol, propanol, isopropanol, buta-
nol, isobutanol, cyclohexanol, benzyl alcohol and aliphatic diols
or polyols, such as ethylene glycol and trimethylol propane.
The 0-alkyl urethanes may either be used as such or may be
~0 produced in situ by reaction with alcohols.
Instead of using the above-mentioned polyisocyanates, it is
- 6 ~
,
.~.. .. . . . . . . . . .
...
1064643
also pos3ible to use the analogous polyisothiocy~nates as starting
materlals.
Pre.~erred cyclic dicarboxylic acid anhydride compounds are
cyclic dicarboxylic acid anhydr~de compounds corresponding to the
general formula:
.. .
R / \ o
" \ /
0
in which R1 represents an optionally substituted aliphatic9 cyclo~
aliphatic 7 heterocyclic ? aliphatic-aromatic or aromatic radical
which, in addition to the cyclic anhydride group, is substituted
at least once be another ~unctional group, such as a cyclic anhy~
dride group, a carboxyl, a carbalkoxy, a carbaroxy or S03H-group.
The following are examples of the carboxylic acid anhydrides
which may be used: . ~
200~ 0\ 0 0 o 0 ~:
H2 C ~ C - C - CH2 ~ C~
o~ b'~ ~ o o ~ o
,0~0~o O O O
o ~ ~ N ~ C ~ C
3 0 ~ 0 ~ HOOC 0
~ L~ 2~ - 7 ~
IL~64~i43
o o
,. ..
~c ~ ~ C~ X = -o-, ~S-, -S02-,
\ ~ X J~ C/O -C-, -N=N-,
~ ~. O
O
C ~,~ ~ X = --NH-C4~-C-NH~ ,
XJ~ COOH O
-C-N~ C,
'. O O
N~ O ~N
O
. . .
O O
" "
n = 1 4, preferably 2 -c-o(-cEI2)n-o-c-
O O
. " "
-C-O~O-C~
; ' ~;:
H~--O--R '' 1~ C ~:
H2-C O-R "
O
., j.
:
~ - 8 - .
1~6~ 3
Instead of uCing the c~rboxylic acid anhydrides~ it is
al~o po~sible to use other acid derivative~ or ~he polycarboxylic
acid i-tself, for example the correspondlng phenyl e~ters which
ma~ be converted during the reaction into acid anhydrides~ Tri-
mellitic acid anhydride is preferably used. The reaction accor-
ding to the invention may be carried out in inert solvents which
do not react under the reaction conditions or which form only
those loose addition compounds which further react.
Suitable solvents are optionall~ halogenated hydrocarbon~,
phenols, esters, ketones, ethers, substituted amides;
nitriles, phosphoric acid amides, sulphoxides and sulphones, .;
for example xylenes, o-dichloroben~ene, phenol, cresols,
acetophenone, cyclohexanone, glycol monomethyl ether acetate,
N methyl pyrrolidone, dimethyl formamide, dimethyl acetamide,
benzonitrile, hexamethyl phosphoric acid triamide9 dimethyl
QZulphoxide, tetramethylene sulphone and mixtures thereof.
., It is preferred to use dimethyl ~ormamide, dimethyl acetamide,
N-methyl pyrrolidone and aromatic alkyl compounds.
The process according to the inventlon is carried out
by keeping the reaction components for a few minutes to
several hours at temperatures in the range from 0 to 450C
in the presence or absence of a solvent. The reacticn is
over when th~ evolution of ga~ stop~ and viscosity increases.
In some cases, it is advantageou~ to carry out the reaction
in several stages or to add the individual component3 in a
different order or at di~ferent temperatures. Thus, an
adduct or condensate may be prepared in a first stage, for
example in a sol~ent, and may be subsequently converted into
the high molecular weight condensation product at elevated
temperatures with evaporation o~ any solvent present, and
'
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~L~6~6~3
chain extension or cross-linking.
In some ca~es, it i~ advisable to carry out the reactlon
under an inert gas atmesphere, such as nitrogen or argon. The
reaction may be carried out either continuously or in batches,
or even under pressure in an autoclave, for example in order to
reach a higher reaction temperature.
Generally it is advantageous to react the polyisocyanates
and the polycarboxylic acid anhydride~ in equivalent amounts to
the reactive groups or to an excess of up to 10 % of isocyanate
or carboxylic acid groups, although even fairly considerably de-
viations from these stoichiometric ratios are also possible. -
The formic acid is used in quantities o~ from 0.1 to 40
mol % and preferably in quantities of from 2 to 15 mol %, based
on the isocyanate. In addition, the condensation products may be
modi~ied by using and incorporating, ~or example, polyols, p~ly-
carboxylic acids, polycarbamic acid esters and also polyesters
and polyethers. Examples include o~thylene glycol, trimethylol
propane, isophthalic acid, trimesic acid, a polycarbamic acid
ester of 2,~-tolylene dii~ocyanate and ethylene glycol, a poly- ;~
ester o~ terephthalic acid, ethylene gl~col and glycerol and a
polyether o~ bis-(hydroxy phenyl)-propane and epichlorhydrin.
~he reaction according to the invention may be influenced
by catalysts, for example boron tri~luoride and its adducts,
ami~es such as triethylamine, l,4-diaza-bicyclo-(2,~,2~-octane,
N-ethyl morpholine and N-methyl imida~ole, phenols such as
phenol and m-cresol and organic and inorganic metallic
compounds, especially of iron, lead, zinc, tin, copper, cobalt
and titanium, such as iron(III)chloride) cobalt acetate,
lead oxide, zinc octoate, dibutyl tin dilaurate, copper
acetyl acetonate and titanium tetrabutylate, and phosphorus
~ - 10 -
~ ' ' ' ! ~ , '
~:D64~ 3
compounds such as trialkyl phosphine and 1-methyl phospholine
oxide.
The imide~group-containing polycondensates according to the
invention, pre~erably poly(amide)imides which may be optionally
modified by admixture with polyesters, are eminently suitable ~or
the production of high-temperature~resistant metal coatings. The
; lacquers according to the invention may be applied to metal plate
o~ any kind in known manner. Aluminium or steel plate is prefe-
rably coated. They are also eminently suitable for the production
of high-temperature-resistant wire lacquers, films or laminates
which may optionally be modified by admixture with polyesters.
The films and laminates are produced by known methods by casting
the polymer solution onto a substrate and evaporating the sol-
vent. In wire lacquering, the wire generally passes through a
lacquer bath subsequent to which the excess lacquer is stripped
of~ by means of a special stripper system. The stripper system
may consist o~ two felts pressed onto one another through which
the wire is guided. However, this required a lacquer of relatively
low viscosity, as is the case with polycondensates regulated in
in accordance with the invention. Accordingl~, a solids content
of up to about 40 %, preferably ~rom 20 to ~0 %, is desirable.
The diameter of the wire to be lacquered is also an important
factor. The increases in the diameter of the wire obtained by
lacquering are laid down in DIN Speci~idcations 46 453 and 46 435.
2$ A solution with a relatively high solids content is normally
stripped b~ means o~ metallic str;pper nozzles. The wire then
passes through a stoving oven in ~hich the solvent is evaporated
and the lacquer film hardened under the effect of heat. This
process is repeated until the required layer thickness has been
obtained. From 6 to 8 passes are generally required ~or this
purpose.
Le A 15 953
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6~3
EXAMPLE 1
a) 192 g of tri~ellitic ~cid anhydride, 253 g of
4,4l-diisocyanatodiphenyl methane and 4.6 g of formic acid
are introduced into 501 g of N-methyl pyrrolidone, followed
by stirring for 4 hours at 85C. Sondensation is acoompanied
by the evolution of gas and i9 completed over a periad of
4 hours at 120~C and 1 hour at 140C. ~he reaction
`~ product is obtained in the form of a brown ~iscous
solution and, its infrared spectrum, shows bands
characteristic of imide groups at 1720 cm 1 and
1775 cm 1. The solution has a viscosity of 25~800 mPa s
at 20C. :
The solution thus obtained is diluted to a solids
content of 30 % with a solvent mixture of N-methyl
pyrrolidone and xylene in a ratio of 1:9. The dilute
solution h~s a viscosity of 950 mPa s.
A 0.7 mm diameter copper wire is lacquered with this
solution to a diameter of 0.75 ~m in a wire lacquering
machine.
~urnace length: 4 metres ~.
furnace temperature: 400C
strlpper system: nozzles
number of passesa 6
Under these conditions, the take-off rate of the
wire can be increased up to 19 metres per minute without
any deterioration in the properties of the lacquer~
especially its softening temperature. The lacquer has
a softening tempera-ture of 380C, as measured in
accordance with DIN 46 453/5.2.3.
b). Comparison Example without formic acid:
~ - 12 - .
.. . . . . . ....
~64~3
500 g of 4,4~-diisocyanatodiphenyl methane are
added to a solution of 384 g o~ trimell~tic acid anhydride
in 1680 g of N-methyl pyrrolidone, and the mi~ture stirred
for 6 hours at 80C and for another 6 hours at 200C.
A light brown solution having a solids content of approx-
imately 30 ~ is obtained, its viscosity amounting to 15,000
mPa s.
In order to obtain a viscosity suitable for processing,
the solution has to be dlluted to a solids content of at
least 24 %. The maximum take-off rate of the wire which
; can be obtained during lacquering amounts to 14 metres per
minute.
EXAMPLE 2
a) For lacquering a 0.1 mm diameter wire, the lacquer
solution prepared in accordance with Example la) is diluted
to a solids content of 23 ~ with a solvent mixture of
N-methyl pyrrolidone and xylene in a ratio o~ 1:2.
The v1900sity of the dilute solution, amounting to
38 seconds (DIN 55 211, number 4 eup), en~bles the felt
stripper system to be used. Under the following lacquering ~.
conditions:
horlzontal furnace: 125 metres long
furnace temperature: inlet 450C, outlet 500C
number of passes: 6
it was possible to obtain wire with excellent properties
up to a take-off rate o~ 130 metres per minute. The
wires thus lacquered had a softening temperature o~ 380C,
as measured in accordance with DIN 46 453/5.2.3.
b) The comparison lacquer obtained in accordance with
lb) has to be diluted to a solids content of approximately
Le A 15 953 - 13 -
~64~j43
17 % ln order to reach the same ~iscosity suitable for
l~cquerlng~ However, the maximum take-off rate which can be
obtained with this solution amounts to only 80 metres per minute.
EXAMPLE ~
: 5 A 0.108 mm diameter polyurethane lacquered wire is
lacquered in two passes to a diameter o$ 0.112 mm with the
lacquer solution obtained in accordance wi$h Example 2a)
having a solids content of 23 % without the polyurethane
film undergoing ~ny heat damage. The stoving conditions
are the same as in Example 2b). The lacquer has a
: softening temperature of 380C, as measured in accordancewith DIN 46 453/5.2.3~ ;-
EXAMPLE 4
A 0.7 mm diameter lncquered wire is provided in a
single operation with 4 coats of lacquer A and then with
2 coats of lacquer Bo
Lacquer A is obtained by dilutin~ a mixture of :`
100 parts by weight of polyvinyl formal having an OH-content
of 5 to 6 ~
60 parts by weight of masked polyisocyanate, obtained by
reaeting tolylene diisocyanate, trimethylol propane,
butylene glycol and phenol, ~
5 parts by weight of a melamine-formaldehyde resin, ::
5 parts by weight of a phenol-formaldehyde resin
: 25 into a 22 ~ solution with a solvent mixture o~ cresol and
xylene in a ratio of 7~
Lacquer ~ is obtained by diluting 1000 parts by weight ~ .
of the lacquer solution obtained in accordance with Example la)
with 400 parts by weight of xylene. The ~ilute solution
has a viscosity of 800 mPa s. The solution may be used in
~ - 14 -
~1~64643
this concentr~tion for wire lacquering.
furnace length: 4 metres
furnace temperature: 400~C
application system: nozzles
take-o~f rate: 11-15 m/min
increase in diameter by
lacquering 55 ~m
In this case, the heat effect required for
hardening the polyamide imide film does not damage the
base by virtue of the high take-off rate. The softening
temperature amounts to 380C~ as measured in accordance
with DIN 46 453/5.2.3.
EXAMPLE 5
80.1 g of phenylene-1,3-diisocyanate, 126.1 g of
4,4~-diisocy~natodiphenyl ether, 192 g of trimellitic
acid anhydride and 6.9 g of formic acid9 are introduced
into 470 g of N-methyl pyrrolidone, followed by stirring
for 4 hours at 80C ~or 4 hours at 120C and for 2 hours
at 140C, The reaotion produot is a brown Vi900US
solution having a visoosity of 1100 mPa s. A woven glass-
filament ~abric i9 impregnated with the solution and dried~
in air. This is ~ollowed by preoondensation ~or 20 minutes
at approximately 150C. Several fabrics impregnated in this
way are then placed one on top of the other and hardened
under pressure at elevated temperature in a press. The
pressure should not exceed 50 kg/cm2 during the first few
minutes, and may then be increased to approximately
150 kg/cm2, The temperature of the press is between
180 and 200C. The total residence time in the press
is goYerned by the number of layers. It amounts to
1e A 15 953 - 15 -
~-- .
10~46~3
abou-t 10 minutes for a panel approximately 3 mnl thick.
A solid heat-resistant laminate ~s obtained.
E~AMPLE 6
. ~ _
18.l~ g of a 10 ~ solution of formic acid in dimethyl
acetamide are added dropwi.se at 70C to a solution Or 340 g
of tolylene-(~,4)-diisocyanate and 384 g of trimelliti( acid
anhydride in 1280 g of N-methyl pyrrolidone. This is followed
by stirr~ng for 5 hours at 80C, for 4 hours at 120C and
for 2 hours at 130C. A light brown solution of the
condensation product is obtained. Imide bands: 1720 cm 1
and 1780 cm 1. Viscosity ~ 20: 4460 mPa s.
The solution thus prepared i9 applied using iR ca~ting
; machine in a predetermined thickness to a heat-resistant
substrate which may consist, for example, of metal or glass
and ~rom which the completed film may readily be removed.
The solvent is evaporated and the film hardened to completion
by heating to a temperature of ~rom 140 to 200C. The film
thus produced show~ ~avourable mechanical properties and high
thermal stability.
The imide-group-containing polycondensates according
; to the invention~ pre~erably poly(amide)imides which may be
optionally modified by admixture with polyesters, are
eminently suitable for the production of high-temperature-
; resistant metal coatings. The lacquers according to the
invention may be applied to metal plate of any kind in
kno~ manner. Aluminlum or steel plate is preferiably
coated.
EXAMPLE 7
I a) 192 g Or trimellitic acid anhydride, 250 g of 4,4~-
diisocyanato diphenyl methane and 2.8 g of ~ormic acid are
,
Le A 15 953 - 16 -
. . . . . . . . . . . .. ., - ..... . . . .. .
11)6~64;3
stirred in 365 g of dimethyl acetamide for 1 hour at 65C,
for 4 hours at 85C and for 4 hour~ at 120 ~ A light
viscous solution of the imide-group-containing condensation
product is obtained. The infrared spectrum of the
condensation product shows the typical imide bands at
1720 cm 1 and 1775 cm 1. After dilution with 485 g of
N-methylpyrrolidone to form an approximately 30% solution,
the viscosity ~ 20 amounts $o 1800 mPa s.
b) 150 g of a 30% solution of the reaction product in
N-m~thyl pyrrolidone/dimethyl acetamide in a ratio of 4.5:6
are stirred with 33.7 g oi rutile TiO2 (Bayertitan ~ R-FD~
followed ~y dilution to a solids content of 3909% with
71 g of a solvent mixture of N-methyl pyrrolidone ~nd
dimethyl acetamide (4.5:6). The resulting solution has a
flow-out time o~ 50 seconds, as measured in accordance with
DIN 53 211.
The lacquer is sprayed onto an aluminium or Erichsen
plate and stoved for 10 minute~ at 250~Co The lacquer
is the~ tested for gloss according to Gardner at 60C
Erich~en value (E) according to DIN 53 156, pencil hardness
j according to DIN 46 453 and impact indentation using a
type 304 Gardner ball impact tester. The results are
shown in Table 1.
c) 150 g o~ a 30% solution of the condens~tion product
obtained as described above in N-methyl pyrrolidone/dimethyl
acetamide(4.5:6) are stirred with 33.7 g of rutile TiO2
~Bayertitan ~ R-FD~I) and the resulting solution diluted
with 60.2 g of di~ethyl formamide to form a solution with
a solids content of 32.3~.
This B0 lution has a flow-out time o~ 50 seconds~ as
Le A 15 953 - 17 -
''
, - , ,, , ............... .,, ~ ~ . . . .
.
1~64~43
measured in accordance with DIN 53 211.
The lacquer solution is sprayed onto an aluminium or
Erichsen plate and stoved for 10 minutes at 250C. The
properties of the lacquer, determined as described above,
are set out in Table 1.
II a) Comparison Example without formic acid:
500 g ~f 4,47-diisocyanato diphenyl methane are added
to a solution of 384 g of trimellitic acid anhydride in
1680 g of N-methyl pyrrolidone, and the mixtures stirred for
6 hours at B0C and then for another 6 hours at 200C~ A
30~ light-brown solution is obtained. ~ ~;
b) 33~7 g of ru$ile TiO2 (Bayertitan ~ R-FD-I) are
stirred into 150 g of this solution, followed by dilution
with 140 g of dimethyl acetamide to form a solution having a
: 15 solids content of 24~3%o This solution has a flow-out
time of 50 seconds~ as measured tn accordance with DIN 53 211.
The lacquer solution is app:lied as described in I b)
and the properties of the lacquer determined in accordance
with I b), are set out in 'rable :l.
c) 47.5 g of rutile TiO2 (Bayertitan ~ R-FD~I~ are
stirred into 200 g of a 30~ solution of the polyamide imide
obtained as described above, and the solution dlluted to
~ a solids content of 25~1 % with 240 g of a solvent mixture ~:
/ of 20 parts of N-methyl pyrrolidone, 10 parts of xylene,
3 parts of ethyl glycol and 3 parts of methanol, This
solution has a flow-out time of 50 seconds.
The solution is stoved to form a lacquer in the same
way as described in I b), the properties of this lacquer
being set out in Table 1.
: Le A 15 953 - 18 -
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1~64~i43
Table 1
__ _ _
colour lacquer layer gloss E-value hardnessimpact indent-
thick- 60% [mm] 2QC 180 C ation ten-
ness Gardner compres~ sile
4m] sion zone zone
light~rI b) lO 75 6~8 > 7H > 7H 34in _ 34
~arkerII b) 9-10 57 7.1 ~ 7H ~ 7H 34 40
_ . . .......... ._ . _
lighter I c) 13 lO0 6.8 7H 7H 34 34
~arker1I c~ 8 57 7.1 7H 7H 34 38
~ .
EXAMPLE 8
192 g of trimellitic acid anhydride, 253 g of 4,4'-diisocyanato
diphenyl methane and 4.6 g of ~ormic acid are introduced into S01 g of
N-methyl pyrrolidone, followed by stirring for 4 hours at 85C, Condensation
is accompanied by the evolution of gas and is completed over a period of
4 hours at 120C and 1 hour at 140C. The reaction product is obtained in
the form of a brown viscous solution and in its infrared spectrum, shows
bands characteristic of imide groups at 1720 cm 1 and 1775 cm 1. The
solution has a viscosity of 25800 mPa s at 20C
EXA~LE 9
18.4 g of a 10~ solution of formic acid in dimethyl acetamide -
are added dropwise at 70C to a solution of 340 g of tolylene-2,4-
diisocyanate and 384 g of trimellitic acid anhydride in 1280 g of N-methyl
pyrrolidone. This is followed by stirring for S hours at 80C, for 4
hours
'`
-19 `~ .
. .. .
, . . . . . . ..
at 120C and ~or 2 hours at 130C. A light brown
solution of the condensation product is obtained.
Imide bands: 1720 cm 1 and 1780 cm 1
Viscosity: ~ 20 = 4460 m Pa s.
EXAM O
96 g of trimellitic aeid anhydride, 1.4 g of fo~ic
acid and 140.4 g of bis-L4-isocyanato phenyl]-propane are
stirred in 250 g of N methyl pyrrolidone and 192 g of
di.methyl acetamide for 6 hours at 80C, for 4 hours at
120C and for 2 hours at 130C. A light brown viscous
lacquer solution with a viscosity of 960 m Pa s is
obtained. The solution is diluted with xylene and stoved
at 200 and 300C to form an elastie laequer film. ?
EXAMpLE 11
80,1 g of phenylene-(1,3)-diisoeyanate, 126.1 g of
4,49-diisoeyanatodiphenyl ether, 192 g of trimellitio aeid
~: anhydride and 6.9 g of ~ormio aeid are introduoed into
470 g of N-meth~l pyrrolidone, ~ollowed by stirring for
4 hours at 80C, for 4 hours at 120C and ~or 2 hours at
140C. The reaetion produet is a brown viseous solution
whieh is eoated onto a plate and stoved ~irst at 200C
and then at 300C to form a clear elastie laequer film.
The:solution is eharaeterised by imide bands at 1715 em 1
and 1775 cm 1. Yiseosity: ~ 20 = 1100 m Pa s.
' . ~
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Le~A 15 953 - 20 -
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