U.S. patent application number 09/381174 was filed with the patent office on 2002-06-27 for impregnating, casting and coating compounds for electrotechnical and/or electronic components and for carrier materials for plane insulating materials.
Invention is credited to BLUM, RAINER, EICHHORST, MANFRED, HEGEMANN, GUNTHER, LIENERT, KLAUS-WILHELM.
Application Number | 20020082314 09/381174 |
Document ID | / |
Family ID | 7823878 |
Filed Date | 2002-06-27 |
United States Patent
Application |
20020082314 |
Kind Code |
A1 |
BLUM, RAINER ; et
al. |
June 27, 2002 |
IMPREGNATING, CASTING AND COATING COMPOUNDS FOR ELECTROTECHNICAL
AND/OR ELECTRONIC COMPONENTS AND FOR CARRIER MATERIALS FOR PLANE
INSULATING MATERIALS
Abstract
The subject of the present invention is the use of a resin
composition (A) comprising A1) at least one unsaturated polyester
resin, A2) at least one vinyl ether having a viscosity of less than
4000 mpa.multidot.s at 25.degree. C., A3) if desired, at least one
further polymer and/or oligomer, A4) if desired, at least one
curing accelerator, A5) if desired, at least one ethylenically
unsaturated reactive diluent, and A6) if desired, further customary
additives, as impregnating, casting and coating compositions for
electrical and/or electronic components and for carrier materials
for sheetlike insulating materials. The present invention
additionally relates to coating compositions suitable for this
purpose which can be cured with low emissions.
Inventors: |
BLUM, RAINER; (LUDWIGSHAFEN,
DE) ; EICHHORST, MANFRED; (OSTSTEINBEK, DE) ;
HEGEMANN, GUNTHER; (HAMBURG, DE) ; LIENERT,
KLAUS-WILHELM; (HAMBURG, DE) |
Correspondence
Address: |
PILLSBURY WINTHROP LLP
1600 TYSONS BOULEVARD
MCLEAN
VA
22102
US
|
Family ID: |
7823878 |
Appl. No.: |
09/381174 |
Filed: |
February 2, 2000 |
PCT Filed: |
March 16, 1998 |
PCT NO: |
PCT/EP98/01513 |
Current U.S.
Class: |
522/111 |
Current CPC
Class: |
H01G 4/224 20130101;
Y02P 20/582 20151101; C09D 167/07 20130101; C08L 67/07 20130101;
C09D 167/06 20130101; C08L 67/06 20130101 |
Class at
Publication: |
522/111 |
International
Class: |
C08J 003/28 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 19, 1997 |
DE |
197 11 410.5 |
Claims
1. The use of a resin composition (A) comprising A1) at least one
unsaturated polyester resin, A2) at least one vinyl ether having a
viscosity at 25.degree. C. of less than 4000 mPa.multidot.s, A3) if
desired, at least one further polymer and/or oligomer, A4) if
desired, at least one curing accelerator, A5) if desired, at least
one ethylenically unsaturated reactive diluent, and A6) if desired,
further customary additives, as impregnating, casting and coating
compositions for electrical and/or electronic components and for
carrier materials for sheetlike insulating materials.
2. The use as claimed in claim 1, wherein the unsaturated
polyesters employed as component (A1) feature, as structural units,
dihydrodicyclopentadiene units of the formula (I) 7and/or
oligodihydrodicyclopentadiene units of the formula (II) 8where n=1
to 10.
3. A solvent-free coating composition which can be cured with low
emissions, comprising A1) at least one unsaturated polyester (A1)
which features, as structural units, dihydrodicyclopentadiene units
of the formula (I) 9.cndot.and/or oligodihydrodicyclopentadiene
units of the formula (II) 10.cndot.where n=1 to 10, A2) at least
one oligomeric and/or polymeric vinyl ether (A2) having a viscosity
at 25.degree. C. of less than 4000 mPa.multidot.s, A3) if desired,
at least one further polymer and/or oligomer, A4) if desired, at
least one accelerator, A5) if desired, at least one ethylenically
unsaturated reactive diluent, and A6) if desired, further customary
additives.
4. The use as claimed in claim 1 or 2 or coating composition as
claimed in claim 3, wherein the component (A3) features, as
structural units, dihydrodicyclopentadiene units of the formula (I)
11and/or oligodihydrodicyclopentadiene units of the formula (II)
12where n=1 to 10.
5. The use or coating composition as claimed in one of claims 1 to
4, wherein the vinyl ethers employed as component (A2) have a
viscosity at 25.degree. C. of less than 2000 mPa.multidot.s and/or
a vapour pressure at 25.degree. C. of less than 5 mbar and/or a
number-average molecular weight of from more than 72 to less than
4000.
6. The use or coating composition as claimed in one of claims 1 to
5, wherein the vinyl ethers employed as component (A2) have a
viscosity at 25.degree. C. of less than 100 mPa.multidot.s and/or a
vapour pressure at 25.degree. C. of less than 1 mbar, preferably
less than 0.2 mbar, and/or a number-average molecular weight of
from more than 250 to less than 2000, preferably less than
1000.
7. The use or coating composition as claimed in one of claims 1 to
6, wherein the dihydrodicyclopentadiene structural units in the
component (A1) and/or in the component (A3) have been incorporated
in the form of esters of the dihydrodicyclopentadienol as in
formula (III) 13and/or wherein the oligodihydrodicyclopentadiene
structural units have been incorporated in the form of esters of
the oligodihydrodicyclopentadienol of formula (IV) 14where n=1 to
10.
8. The use or coating composition as claimed in one of claims 1 to
7, wherein the dihydrodicyclopentadiene structural units in the
component (A1) and/or in the component (A3) have been incorporated
by concomitant use of compounds of the formula (V) 15and/or wherein
the oligodihydrodicyclopentadiene structural units have been
incorporated by concomitant use of compounds of the formula (VI)
16where n=1 to 10.
9. The use or coating composition as claimed in one of claims 1 to
8, wherein the resin composition comprises A1) from 5 to 95% by
weight, preferably from 30 to 80% by weight and, with particular
preference, from 40 to 70% by weight of component (A1), A2) from 1
to 70% by weight, preferably from 5 to 50% by weight and, with
particular preference, from 10 to 40% by weight of component (A2),
A3) from 1 to 80% by weight, preferably from 3 to 30% by weight
and, with particular preference, from 5 to 20% by weight of
component (A3), A4) from 0 to 10% by weight, preferably from 2 to
5% by weight, of component (A4), A5) from 0 to 20% by weight,
preferably from 2 to 10% by weight, of component (A5), and A6) from
0 to 20% by weight, preferably from 0.5 to 10% by weight, of
component (A6), the percentages by weight being based in each case
on the overall weight of the resin composition, and the sum of the
proportions by weight of components (A1) to (A6) being in each case
100% by weight.
10. The use or coating composition as claimed in claims 1 to 9,
wherein component (A1) comprises chemically bonded photoinitiators
which feature xanthone, thioxanthone and/or phenone structures.
11. The use as claimed in one of claims 1 or 2 or 4 to 10, wherein
the resin compositions are cured with high-energy radiation,
especially with UV radiation, the photoinitiators that may be
necessary either being present in chemically bonded form in the
resin composition and/or having been added to the resin
composition.
12. The use as claimed in one of claims 1 or 2 or 4 to 9, wherein
the resin compositions are cured with peroxides, with or without
reaction-accelerating co-initiators, at room temperature or at
elevated temperature, possibly first of all up to a partially cured
B-stage, before being cured to completion later on.
13. The use as claimed in one of claims 10 to 12, wherein the resin
systems are cured both thermally and with high-energy radiation.
Description
[0001] The present invention relates to the use of unsaturated
polyester resins as impregnating, casting and coating compositions
for electrical and/or electronic components and for carrier
materials for sheetlike insulating materials.
[0002] The present invention also relates to coating compositions
suitable for this purpose which can be cured with low levels of
emissions.
[0003] By impregnating, casting and coating compositions are meant,
according to the present application, resin compositions that are
employed in electrical engineering by the commonly known methods of
dip impregnation, the trickle technique, the dip-rolling technique,
the flooding technique and the process of casting for the
impregnation of windings or the like, these methods possibly being
assisted by the application of reduced and/or superatmospheric
pressure. This term also embraces the impregnation of carrier
materials for sheetlike insulating materials, such as glass fibres,
mica tapes and other absorbent materials, and combinations thereof,
and in this context one option is to terminate curing at the
B-stage in order to obtain curable prepregs.
[0004] The windings of electrical machines are customarily
impregnated by saturation. The function of this impregnation is to
induce a mechanical strengthening of the winding, so that the
winding is able to absorb mechanical and electromechanical forces,
so that the winding is protected against harmful external
influences, such as, for example, the deposition of dust particles,
collector abrasion, humidity, salts and solvents, so that
mechanical damage due to particles sucked in, for example, by the
fan is prevented and so that the heat which develops when the
electrical machines are operated can be dissipated by ohmic and
dielectric losses from the winding to the surrounding cooling
devices, which contributes to prolonging the service life of the
electrical device.
[0005] The impregnation of these windings, or the
coating/impregnation of other electrical and/or electronic
components, is usually carried out by means of resins or lacquers
which cure to form thermosets. Since firstly the requirements on
the long-term thermal stability of these thermosets are very high
and secondly the properties set out above, especially the
electrical insulation capacity, must be provided, there are a range
of lacquers and resins that are tailored to the specific fields of
use.
[0006] In the case of the solvent-containing lacquers, whose
solvent fraction must be removed prior to the curing operation, the
penetrative extent of impregnation of the electrical windings is
generally poor in the case of a single application. This hinders
the dissipation, already referred to above, of ohmic and dielectric
heat losses from the interior of the windings. In addition, the
removal of the solvent often necessitates long preheating periods
and complex temperature regimes for the curing of the lacquer. With
the solvent-containing lacquers, moreover, expensive apparatus is
required for cleaning the waste air, since otherwise there is
considerable pollution of the environment as a result of solvent
vapours.
[0007] For this reason the lacquers in the electrical industry,
aside from special cases, have been replaced by solvent-free
resins. Here, the unsaturated polyester resins in particular have
come to occupy a broad area, since they have considerable
advantages over other thermosetting resin systems. For example, the
properties required can to a large extent be met by molecular
tailoring of the unsaturated polyester resins: for example, the
selection of specific monomer building blocks or the establishment
of specific molecular weights. In addition, the reactivity of the
unsaturated polyester resins can be influenced in such a way as to
permit short and hence cost-effective production processes for
windings of electrical machines.
[0008] The unsaturated polyester resins, and especially the
unsaturated polyesterimide resins, have particularly outstanding
properties with respect to the requirement of long-term heat
resistance in particular.
[0009] In general, the unsaturated polyester resins are constructed
on the one hand from base resins consisting, for example, of
alpha,beta-unsaturated dicarboxylic acids, further, modifying
mono-, di- and/or polycarboxylic acids, di- and/or polyols and, in
the case of polyesterimides, from imide-functional hydroxyl- and
carboxyl-containing building blocks, and on the other hand from
comonomers which react with the alpha,beta-unsaturated dicarboxylic
acid units of the base resin and are able to lead to thermosets. A
preferred comonomer is styrene, which owing to its good dissolution
properties is also used to establish the processing viscosity.
Under appropriate conditions in the course of curing, the
comonomers are fully copolymerized. A solvent-free system of this
kind is dubbed an impregnating resin. As with the impregnating
lacquers, the vapour pressures of the comonomers give rise at
application temperature to evaporation losses, although generally
lower than those in solvent-containing systems (50%, based on
amount of solvent employed, evaporation loss with
solvent-containing impregnating lacquers, from 10 to 30%
evaporation loss with impregnating resins).
[0010] Nevertheless, even when using impregnating resins based on
unsaturated polyesters there is still a need for the waste air to
be cleaned, although such waste-air units can be given a lower
design cleaning capacity than when impregnating lacquers are used,
since by suitable resin formulations and process adaptations it is
possible to reduce the monomer losses.
[0011] The use of other resin systems, such as epoxy resins, for
example, has the disadvantages that long curing times are
necessary, that the possibilities for adapting the processing
properties to the production processes are small without seriously
impairing the dielectric properties, and that some resin
constituents, such as, in the case of epoxy resins, for example,
the highly heat-resistant cycloaliphatic types and, in the case of
the curing agents, the amines, may have a high toxicity.
[0012] German Patent Application P 195 425 64.2, then, which is not
a prior publication, describes a process for impregnating
electrically conducting substrates which uses free-radically curing
resin systems which in addition to a resin that can be cured
free-radically to form a thermoset, a hardener and, if desired, an
accelerator may also include, if desired, comonomer-free vinyl
ethers. Details of suitable vinyl ethers, however, are not given in
this document.
[0013] German Patent Applications P 196 00 136.6 and P 196 00
137.4, likewise not prior publications, disclose solvent-free
coating compositions comprising polyesters having
dihydrodicyclopentadienyl end groups. These coating compositions in
accordance with German Patent Application P 196 00 136.6 are used
for coating or for printing metal containers, and the coating
compositions in accordance with German Patent Application P 196 00
137.4 are employed, in particular, as printing inks.
[0014] Furthermore, German Patent Applications P 196 00 149.8 and P
197 07 492.8, both not prior publications, disclose the use of
polyester resins having dihydrodicyclopentadiene end groups as
impregnating, casting and coating compositions for electrical and
electronic components. The additional use of vinyl ethers in the
resin compositions is not described in these applications.
[0015] DE-A-31 07 450 describes unsaturated polyester with
oligomers of dicyclopentadiene as end groups, which are used as
solutions in ethylenically unsaturated monomers to produce
mouldings and coatings. The ethylenically unsaturated monomers
employed as reactive diluents are, in general, problematic owing to
their high vapour pressure at room temperature and at processing
temperature, and to the emission problems which this entails.
[0016] EP-A-0 101 585 describes unsaturated polyester resins which
are modified by the addition of cyclopentadiene onto the double
bonds of the unsaturated units of the polyester and are then
dissolved in vinyl monomers as reactive diluents. Again a problem
is the use of vinyl monomers as reactive diluents, from an
ecological and toxicological standpoint.
[0017] EP-A-623 660 discloses free-radically curable coating
compositions comprising unsaturated polyester resins dissolved in
vinyl ether compounds having an average molecular weight of from 72
to 1000. The use of polyesters with dihydrodicyclopentadiene units,
however, is not described. In addition, the coating compositions of
EP-A-623 660 are used as furniture varnish. The mandatory inclusion
of waxes that is prescribed by EP-A-623 660, moreover, makes the
coating compositions unusable for electrical insulation
applications owing to disruptions to the homogeneity in the
component.
[0018] Finally, U.S. Pat. No. 5,252,682 discloses resin
compositions which comprise polyesters having
dihydrodicyclopentadiene units, monomeric vinyl ethers, such as
triethylene glycol divinyl ether and dimethanolcyclohexane divinyl
ether, for example, and cationic initiator. Information on the end
uses of these resin compositions, however, is not described in U.S.
Pat. No. 5,252,682. In particular, there are no references to the
use of these resin compositions in the field of the coating of
electrical/electronic components. Furthermore, the resin
compositions described therein are poorly suited to this field of
use, since the elimination products of the metallic, cationic
initiators, which remain in the cured compositions, unacceptably
impair the dielectric properties of the cured compositions.
[0019] The present invention is therefore based on the object of
providing impregnating, casting and coating compositions for
electrical and/or electronic components and for carrier materials
for sheetlike insulating materials, which compositions do not have
the abovementioned disadvantages of the prior art. In particular,
therefore, these compositions should be able to be cured with low
emissions and should as far as possible be able to be labelled as
monomer-free. Nevertheless, these compositions should have a very
high reactivity, rendering them curable within short times at
curing temperatures that are not too high, so that decomposition
phenomena in the resins, and instances of damage to the materials,
are avoided. Moreover, these compositions must not give off
elimination products to any notable extent under the processing and
curing conditions.
[0020] This object is surprisingly achieved by employing a resin
composition (A) which comprises
[0021] A1) at least one unsaturated polyester resin,
[0022] A2) at least one vinyl ether having a viscosity at
25.degree. C. of less than 4000 mPa.multidot.s,
[0023] A3) if desired, at least one further polymer and/or
oligomer,
[0024] A4) if desired, at least one curing accelerator,
[0025] A5) if desired, at least one ethylenically unsaturated
reactive diluent, and
[0026] A6) if desired, further customary additives.
[0027] The present invention also provides coating compositions
that are suitable for this utility and can be cured with low
emissions.
[0028] In the text below, then, the individual components of the
resin composition will be elucidated further:
[0029] Polyester component (A1)
[0030] As component (A1) the resin compositions used in accordance
with the invention comprise one or more unsaturated polyesters
containing optionally imide-functional building blocks. Of these
constituents, unsaturated polyester resins are fundamentally known.
Imide-functional unsaturated polyester resins are described, for
example, in DE-A-15 70 273, DE-A-17 20 323 and DE-A-24 60 768.
[0031] The unsaturated polyesters are prepared in a known manner
from di- and/or polyfunctional carboxylic acids and di- and/or
polyfunctional alcohols, alone or together with monocarboxylic
acids and/or monoalcohols.
[0032] In addition to maleic and/or fumaric acid, which are
employed with preference, examples of suitable poly-carboxylic
acids are phthalic acid, isophthalic acid, terephthalic acid,
tetrahydro- and/or hexahydrophthalic acid,
endomethylenetetrahydrophthalic acid, malonic acid, succinic acid,
adipic acid, suberic acid, glutaric acid, sebacic acid, azelaic
acid, trimellitic acid, pyromellitic acid, di- and/or
polycarboxylic acids having ethylenically unsaturated structural
units, such as itaconic acid and citraconic acid, for example,
mono- or polyunsaturated fatty acids, such as the fatty acids of
coconut oil, groundnut oil, castor oil, wood oil, soya bean oil,
linseed oil, cottonseed oil or safflower oil, and/or the anhydrides
of the said polycarboxylic acids insofar as they can be
synthesized.
[0033] It is also possible of course, instead of the free acids, to
employ the corresponding esters with lower alcohols or with allyl
alcohol or with other alcohols [lacuna] partially esterified di-
and/or polycarboxylic acids, such as monoallyl trimellitate and
diallyl pyromellitate, for example.
[0034] Examples of diols suitable for preparing the polyesters are
ethylene glycol, propanediols, butanediols, hexanediols, allyl
alcohol, neopentyl glycol hydroxypivalate, neopentyl glycol,
diethylene glycol, cyclohexanediol, cyclohexanedimethanol,
trimethylpentanediol and ethylbutylpropanediol. Also suitable,
furthermore, are aliphatic polyetherdiols, such as linear or
branched poly(oxyethylene) glycols, poly(oxypropylene) glycols
and/or poly(oxybutylene) glycols, and mixed polyetherdiols, such as
poly(oxyethyleneoxypropylene) glycols. The polyetherdiols usually
have a molar mass Mn of from 400 to 3000.
[0035] Other diols which can be employed, furthermore, are aromatic
or alkylaromatic diols, such as, for example,
2-alkyl-2-phenyl-propane-1,3-d- iol, bisphenol derivatives with
ether functionality, hydrogenated bisphenols, and so on.
[0036] Other suitable diols include esters of hydroxycarboxylic
acids with diols, where the diol employed can be the abovementioned
diols. Examples of hydroxycarboxylic acids are hydroxypivalic acid
or dimethylol-propanoic acid.
[0037] Examples of suitable polyols are ditrimethylolpropane,
trimethylolethane, trimethylolpropane, glycerol, pentaerythritol,
homopentaerythritol, dipentaerythritol, trishydroxyethylisocyanate,
1,2,4 butanetriol [sic], propane- and hexane-triols,
trihydroxycarboxylic acids, such as
trishydroxymethyl(ethyl)ethanoic acids, trimethylolethane monoallyl
ether, trimethylolpropane monoallyl ether, trimethylolethane
diallyl ether, trimethylolpropane diallyl ether, pentaerythritol
monoallyl ether, pentaerythritol diallyl ether. The polyols having
at least 3 OH groups can be employed alone or as a mixture. If
desired, the triols can be employed together with monofunctional
alcohols, such as, for example, butanol, octanol, lauryl alcohol,
cyclohexanol, tert-butylcyclohexanol, ethoxylated and/or
propoxylated phenols.
[0038] As di- and/or polyol building blocks it is also possible to
employ oligomeric and/or polymeric di- and/or polyols, such as, for
example: hydroxyl-modified polybutadienes, hydroxyl-containing
polyurethanes or hydroxyl-containing epoxy resins.
[0039] Also suitable for preparing the polyesters are compounds
which have a group that is reactive towards the functional groups
of the polyester. As modifying component it is possible to use
diepoxide compounds, alone or with monoepoxide compounds. Suitable
components are, for example, those described in DE-A-40 24 204 on
page 4, lines 4 to 9. Also suitable are unsaturated glycidyl
compounds, such as glycidyl undecenoate, (meth)acrylicization
products of epoxy resins, allyl glycidyl ether, vinyl glycidyl
ether and, preferably, glycidyl (meth)acrylate. These glycidyl
compounds can be included at the synthesis stage
or--preferably--are added subsequently.
[0040] Compounds suitable for preparing the polyesters include
those possessing, in addition to a group that is reactive towards
the functional groups of the polyester, a tertiary amino group as
well, for example monoisocyanates having at least one tertiary
amino group or mercapto compounds of at least one tertiary amino
group. For details reference is made to DE-A-40 24 204, page 4,
lines 10 to 49.
[0041] Through the (additional) use of di- and/or polyfunctional
amines, such as ethylene diamine, 1,2- and 1,3-propylenediamine,
hexamethylenediamine, phenylenediamine or melamine, for example, it
is also possible to obtain polyesters having amide groups.
[0042] The molecular weight of the polyesters of the invention can
be regulated using monofunctional compounds, such as alcohols, for
example butanol, hexanol or else (oligo)dihydrodicyclopentadienol,
monofunctional amines, for example propylamine or aniline, and
monofunctional carboxylic acids, such as acetic acid or benzoic
acid, for example.
[0043] The polyesters (A) are prepared by the known methods of
esterification, as is described, for example, in DE-A-40 24 204,
page 4, lines 50 to 65.
[0044] This reaction usually takes place at temperatures between
180 and 280 degrees C., possibly in the presence of an appropriate
esterification catalyst such as, for example, lithium octoate,
dibutyltin oxide, dibutyltin dilaurate, para-toluenesulphonic acid,
hydrophosphorous [sic] acid and the like. Non-metallic catalysts
are preferably employed.
[0045] Usually, the preparation of the polyesters is carried out in
the presence of small amounts of an appropriate solvent as
entrainer. Examples of entrainers employed are aromatic
hydrocarbons, such as in particular xylene, and (cyclo)aliphatic
hydrocarbons, for example cyclohexane. In addition, however, it is
also possible to prepare the polyesters without solvent (reaction
in bulk).
[0046] The synthesis of polyesters of the invention that satisfy
specific requirements in relation, for example, to hardness,
elasticity or processing viscosity takes place in accordance with
rules that are known to the skilled worker. For example, the
elasticity of the polyesters can be varied via the chain length of
the incorporated polyols and/or polycarboxylic acids between the
ester linkage points: polyesters with hexanediol and/or adipic acid
building blocks, for example, are more elastic than polyesters with
ethylene glycol and/or phthalic acid building blocks.
[0047] Furthermore, the skilled worker is aware that by
incorporating tri- or higher polyfunctional polyols and/or
polycarboxylic acids, and the associated introduction of branching
points in the polyester molecule, it is possible to influence
critically the properties, especially the viscosity, of the
polyester resins.
[0048] Particular preference is given to the use as component (A1)
of unsaturated polyesters which comprise, as structural units,
dihydrodicyclopentadienyl units of the formula (I) and/or
oligodihydrodicyclopentadienyl units of the formula (II): 1 2
[0049] where n=1 to 10.
[0050] The dihydrodicyclopentadienyl units and/or the
oligodihydrodicyclopentadienyl units are preferably esters of
dihydrodicyclopentadienol, as in formula (III), or esters of
oligodihydrodicyclopentadienol, as in formula (IV): 3
[0051] where n=1 to 10.
[0052] Particularly preferred dihydrodicyclopentadiene units and/or
oligodihydrodicyclopentadiene units are monoesters of
dihydrodicyclopentadienol with maleic acid and/or fumaric acid, as
in formula (V), or monoesters of oligodihydrocyclopentadienol with
maleic acid and/or fumaric acid, as in formula (VI): 4
[0053] where n=1 to 10.
[0054] The dihydrodicyclopentadienyl and the
oligodihydrodicyclopentadieny- l structural units of the formulae
(I) to (VI) are all derived from the starting material
dicyclopentadiene, which in turn is a dimerization product of
cyclopentadiene (regarding the synthesis of cyclopentadiene
compare, for example, Ullmanns Enzyklopdie der technischen Chemie,
4th ed., volume 9, pages 699 to 704, Verlag Chemie, Weinheim,
1975).
[0055] Cyclopentadiene dimerizes spontaneously at room temperature
to form dicyclopentadiene. At temperatures above 100.degree. C.,
preferably at temperatures between 170 and 300.degree. C. and under
pressure, cyclopentadiene reacts with itself, via dicyclopentadiene
as intermediate, to form oligodicyclopentadiene, by the mechanism
of the Diels-Alder reaction. When catalysts are added, such as, for
example, the halides of aluminium, antimony, boron, iron, bismuth
or tin, cyclopentadiene polymerizes in the absence of oxygen to
form polycyclopentadiene with molecular weights of up to more than
10,000 daltons.
[0056] The dihydrodicyclopentadiene and/or
oligodihydrodicyclopentadiene units present in the coating
compositions of the invention are based on the corresponding
dihydrodicyclopentadienol of formula (VII): 5
[0057] or on the corresponding oligodihydrocyclopentadienol of the
formula (VIII): 6
[0058] where n=1 to 10.
[0059] The compounds of the formulae (VII) and (VIII) are available
commercially and are obtainable, for example, from
dicyclopentadiene and oligodicyclopentadiene, respectively, by
adduct formation with water, with or without acid catalysis.
[0060] In the preparation of the binders of the invention the
(oligo)dihydrodicyclopentadienols of the formulae (VII) and (VIII)
can also be employed per se as a synthetic building block.
[0061] The structural units of the formulae (III) and (IV) are
preferably obtainable by reacting dicyclopentadiene or
oligodicyclopentadiene with acids, preferably with carboxylic acids
and, with particular preference, with polycarboxylic acids. Very
particular preference is given to the use as acid of maleic and/or
fumaric acid in amounts such that the corresponding monoesters of
the formulae (V) and (VI) are obtained as structural units. To
prepare the synthetic building blocks according to the formulae
(III) to (VI), the dicyclopentadiene or the oligodicyclopentadiene
is preferably reacted with the (poly)carboxylic acid in the
presence of water at preferably elevated temperature.
[0062] The structural building blocks (III) to (VI), which contain
ester groups, can of course also be obtained by reacting the
corresponding dihydrodicyclopentadienol (VII) or the corresponding
oligodihydrodicyclopentadienol (VIII) with acids, preferably with
carboxylic acid, with particular preference with polycarboxylic
acids and, with very particular preference, with maleic and/or
fumaric acid.
[0063] In a further embodiment of the invention the binders
employed in accordance with the invention are prepared as
follows:
[0064] In a first stage a polyester resin, polyesteramide resin or
polyesterimide resin (prepolyester) is synthesized which features
no structural units of the formula (I) and of the formula (II) but
instead as an excess of free acid groups, resulting from a specific
proportion of hydroxyl groups to acid groups during the polyester
synthesis. In the following stage, the prepolyester is reacted with
dicyclopentadiene, optionally in the presence of catalysts, in a
polymer-analogous manner to give the polyesters having the
structural units of the formulae (I) and/or (II). In the case of
unsaturated prepolyesters having ethylenically unsaturated double
bonds, the addition of cyclopentadiene onto the double bonds occurs
as a side reaction, leading in the case of maleic acid units, for
example, to the formation of endomethylenetetrahydrophthalic acid
structural units.
[0065] It may also be desirable to introduce the
oligodihydro-dicyclopenta- diene structures of formula (II) in
higher proportions in order, for example, to raise the hardness of
the end products.
[0066] Component (A1) is employed in the resin compositions that
are employed in accordance with the invention preferably in an
amount of from 5 to 95% by weight, with particular preference from
30 to 80% by weight and, with very particular preference, from 40
to 70% by weight, based in each case on the overall weight of resin
composition.
[0067] Vinyl Ether Component (A2)
[0068] It is essential to the invention that the resin compositions
employed in accordance with the invention comprise as component
(A2) one or more vinyl ethers having a viscosity at 25.degree. C.
of less than 4000 mPa.multidot.s, preferably less than 2000
mPa.multidot.s and, with particular preference, less than 100
mPa.multidot.s. The vinyl ethers that are employed as component
(A2) preferably, moreover, have a number-average molecular weight
of more than 72 to less than 4000, preferably of more than 250 to
less than 2000 and, with particular preference, of from 300 to less
than 1000. The addition of these vinyl ethers normally on the one
hand reduces the viscosity of the resin compositions and on the
other hand increases the reactivity.
[0069] Examples that may be mentioned of vinyl ethers which can be
used in accordance with the invention are: ethyl vinyl ether,
(iso-)propyl vinyl ether, (iso-)butyl vinyl ether, octadecyl vinyl
ether, ethylene glycol mono- and divinyl ether, diethylene glycol
mono- and divinyl ether, butanediol divinyl ether, hexanediol mono-
and divinyl ether, triethylene glycol vinyl ether,
cyclohexanedimethanol vinyl ether, ethylhexyl vinyl ether,
cyclohexyl vinyl ether, (iso)amyl vinyl ether, trimethylolmono-,
trimethyloldi-, and trimethyloltrivinyl [sic] ether, aminopropyl
vinyl ether and diethylaminoethyl vinyl ether.
[0070] It is preferred as component (A2) to employ vinyl ethers
which have a very low vapour pressure at 25.degree. C., preferably
a vapour pressure at 25.degree. C. of less than 5 mbar, with
particular preference of less than 1 mbar and, with very particular
preference, of less than 0.2 mbar.
[0071] Very particular preference is given, therefore, to the use
of oligomeric and/or polymeric vinyl ethers. These substances
generally have the desired low vapour pressure and are not
hazardous working materials and comply with the statutory
provisions for polymers (cf. e.g. EU Official Journal of 5.6.92,
No. L 154/3).
[0072] Examples that may be mentioned of suitable oligomeric and/or
polymeric vinyl ethers are the following compounds: polyethylene
glycol mono- and polyethylene glycol divinyl ether, polypropylene
glycol mono- and polypropylene glycol divinyl ether, monoalkyl
polyethylene glycol monovinyl ethers, monoalkyl polypropylene
glycol monovinyl ethers, polytetrahydrofuran mono- and
polytetrahydrofuran divinyl ether, monoalkyl polytetrahydrofuran
monovinyl ethers, vinyl ethers of oxalkylated branched polyols,
such as oxalkylated trimethylolpropane or oxalkylated
pentaerythritol.
[0073] The vinyl ethers are employed in the resin compositions in
an amount such that the particular desired processing viscosity and
the desired light sensitivity is achieved. They are therefore
commonly employed in an amount of from 1 to 70% by weight,
preferably from 5 to 50% by weight, and, with particular
preference, from 10 to 40% by weight, the percentages by weight
being based on the overall weight of the resin composition.
[0074] Further Polymer (A3)
[0075] The resin compositions employed in accordance with the
invention preferably comprise in addition one or more further
polymers and/or oligomers. Particularly suitable such polymers
and/or oligomers are those that are reactive under the prevailing
curing conditions. Also suitable, however, are compounds of this
kind that are not reactive. Furthermore, the so-called organic
fillers and/or organic white pigments are also suitable as
component (A3).
[0076] It is particularly preferred to employ, as component (A3),
compounds which are different from component (A1) but which
likewise have the dihydrodicyclopentadiene structural units of the
formula (I) and/or the oligodihydrocyclopentadiene structural units
of the formula (II).
[0077] Such substances employed preferably as component (A3) are
derived from monofunctional alcohols or polyfunctional hydroxy
compounds having more than two hydroxyl groups per molecule, some
or all of which have been esterified with monocarboxylic acids of
the formulae (V) and/or (VI), but which may also in part have been
esterified with other substances or etherified.
[0078] Furthermore, the substances suitable for component (A3) can
be derived from monofunctional or polyfunctional amine compounds
which have been reacted either in whole or else in part with
monocarboxylic acids of the formulae (V) and/or (VI) to form amides
or salts.
[0079] Furthermore, the substances suitable for component (A3) can
be derived from monofunctional or polyfunctional epoxide compounds
which have been reacted either in whole or else in part with
monocarboxylic acids of the formulae (V) and/or (VI).
[0080] Examples that may be mentioned are substances suitable as
component (A3) are the esters of compounds of the formula (V)
and/or (VI) with mono- and polyalcohols, such as butanol, hexanol,
butanediol, hexanediol, polyethylene glycol monoalkyl ethers,
polypropylene glycol monoalkyl ethers, trimethylolpropane,
pentaerythritol or more highly functionalized hydroxyl compounds or
hydroxyl-functional diene oils. Other suitable polyols for
esterification with substances of the formulae (V) and/or (VI) are
hydroxyl-functional saturated polyesters. The substances suitable
as component (A3) may also be obtained from carboxy-functional
saturated polyesters or other hydroxyl-reactive mono- or
polyfunctional compounds, which are reacted with
(oligo)dihydrodicyclopentadienyl alcohol of the formulae (VII)
and/or (VIII). Also of particular importance are the esters of the
ethoxylation and propoxylation products of hydroxyl compounds, and
also polyester- and polyetherpolyols of the polyethylene oxide,
polypropylene oxide, polytetrahydrofuran and polycaprolactone
type.
[0081] By way of the nature of the alkoxylating agents and the
degree of alkoxylation it is also possible to control properties of
the end products such as, for example, hardness, hydrophilicity and
elasticity. It is also possible for such polyols to have been only
partly esterified with compounds of the formulae (V) and (VI), the
remaining hydroxyl groups either remaining free or being able to be
etherified or esterified with other substances or to be reacted
with other, hydroxyl-reactive substances. Examples of suitable such
substances are isocyanates or epoxides. Hydroxyl-containing natural
oils, such as castor oil, for example, are also of importance.
[0082] Further substances suitable as component (A3) include
adducts of compounds of the formula (V) and/or (VI) with
epoxides.
[0083] Further substances of the type mentioned are reaction
products of carboxylic acids of the formulae (V) and/or (VI) with
mono- or polyfunctional amines. These reaction products can be
saltlike adducts, but are preferably amides. Examples are the
reaction products of amino-functional polyethylene oxides,
polypropylene oxides or diene oils with compounds of the formula
(V) and/or (VI).
[0084] The compounds that are employed as component (A3) are
preferably prepared separately and then mixed with the polyesters
(A1) employed in accordance with the invention, optionally with
curing accelerators (A4), optionally with reactive diluents (A5)
and optionally with auxiliaries (A6) to form ready-to-use
electrical insulating compositions. In many cases, however, it is
also possible to prepare such substances in situ in the course of
the polyester preparation by appropriate adjustment of the
stoichiometric proportions.
[0085] In the resin compositions employed in accordance with the
invention, component (A3) is preferably employed in an amount from
1 to 80% by weight, with particular preference from 3 to 30% by
weight and, with very particular preference, from 5 to 20% by
weight, based in each case on the overall weight of the resin
composition.
[0086] Curing Accelerator (A4)
[0087] As component (A4), the resin compositions employed in
accordance with the invention include from 0 to 10% by weight,
preferably from 2 to 5% by weight, based on the overall weight of
the resin composition, of curing accelerators for catalyzing the
free-radical polymerization. These curing accelerators are
generally compounds which by photolytic and/or thermal means form
free radicals for initiating the free-radical polymerization.
[0088] Examples suitable for photolytic initiation of the
free-radical polymerization are benzoin, benzoin ethers,
substituted benzoins, alkyl ethers of substituted benzoins, such as
alpha-methylbenzoin alkyl ethers or alpha-hydroxymethylbenzoin
alkyl ethers, for example; benzils, benzil ketals, such as benzil
dimethyl ketal or benzil methyl benzyl ketal, for example;
ketone-based initiators, such as, for example, acetophenone and its
derivatives, such as diethoxy-acetophenone or m-chloroacetophenone,
benzophenone and its derivatives, such as
4,4'-dimethylaminobenzophenone or 4,4'-diethylaminobenzophenone,
propiophenone, hydroxycyclohexyl phenyl ketone,
2-hydroxy-2-methyl-1-phenyl-propan-1-one; antraquinone [sic] and
its derivatives, and also thioxantone [sic] and its derivatives,
and also mixtures of different curing accelerators.
[0089] In this context, the curing accelerators can also be bonded
chemically to the components of the resin composition, and
especially to component (A1). The curing accelerators with H
acceptor groups are preferably used in a form in which they are
bonded polymerically to the polyesters; for example, by the
concomitant use of pure-condensable phenone, xanthone and/or
thioxanthone compounds, such as, for example, hydroxy- or
bishydroxybenzophenone or benzophenone carboxylic acids and/or
benzophenonecarboxylic esters, in the course of the
polycondensation of the polyester resins.
[0090] Examples suitable for the thermal initiation of the
free-radical polymerization are conventional peroxides,
hydroperoxides, azo compounds, azides or thermally labile C--C
compounds, such as highly substituted ethanes, for example.
[0091] A considerable acceleration in the curing, or reduction in
the curing temperature, is possible using metal co-initiators, such
as cobalt manganese, iron, nickel or lead compounds.
[0092] Alternatively, the coatings can be cured thermally and/or by
means of UV or electronic radiation, preferably UV radiation,
without the use of photoinitiators.
[0093] For the curing of the coating compositions of the invention
it is possible, furthermore, to employ mixtures of thermal and
photolytic initiators.
[0094] The preferred use of stabilizers in combination with the
curing accelerators is favourable for good stability of the resin
compositions in the course of processing. Particularly suitable in
this context are the stabilizers of the type of the hydroquinones,
of the quinones, of the alkylphenols and/or alkylphenol ethers.
Examples hereof are hydroquinone, methylhydroquinone,
p-benzoquinone, secondary and tertiary methylphenols, tertiary
butylphenols, tertiary amylphenols, octylphenols, butylated
xylenols and butylated cresols.
[0095] It is particularly favourable in this context to employ the
stabilizers as mixtures. In this case at least 2 of the stated
stabilizers should be employed in order to ensure firstly that the
impregnating resins are thermally stable up to a temperature of
50.degree. C. over a prolonged period and secondly that reaction of
the impregnating resin compositions is no longer prevented at a
curing temperature of 100.degree. C. The stabilizers are used in
customary amounts. The overall amount of the stabilizers employed
can amount, for example, to from 0.005 to 0.5% by weight,
preferably from 0.01 to 0.1 and, with particular preference, from
0.01 to 0.05% by weight, based on the overall composition. The
quantitative ratios between the stabilizers can vary within broad
ranges; in the case of the use of 2 stabilizers, for example, they
may lie at a ratio of from 1:1 to 20:1, preferably from 1:1 to 10:1
and vice versa. Similar ranges are possible when more than 2
stabilizers are employed. Mixtures of stabilizers of the quinone
type with those of the alkylphenol type are particularly
suitable.
[0096] Reactive Diluents (A5)
[0097] In addition it is technically possible to employ in minor
amounts--preferably in an amount from 0 to 20% by weight, and with
particular preference from 2 to 10% by weight, based on the overall
weight of the resin composition--the known ethylenically
unsaturated reactive diluents, examples being styrene,
vinyl-toluene, allyl ethers, allyl esters, .alpha.-methylstyrene,
vinylcarbazole, vinylcaprolactam, vinylpyrrolidone, mono- and
oligomeric, mono- and/or polyfunctional acrylates and vinyl esters.
Hence it is possible, for example, to formulate low-styrene
compositions while obtaining the other good properties of the
compositions of the invention, in order, for example, to keep below
statutory limits on the concentrations or emissions of styrene.
[0098] Additives (A6)
[0099] If desired, the resin compositions may also comprise
customary additives (A6) in customary amounts, preferably in an
amount of from 0 to 20% by weight and, with particular preference,
from 0.5 to 10% by weight.
[0100] Examples that may be mentioned of suitable compounds are:
surface-active substances, such as ionic and nonionic surfactants,
for example, and also fluorinated surfactants, antifoams,
plasticizers, such as phthalates, adipates and phosphates, and the
like.
[0101] If desired, the resin compositions may also include soluble
and insoluble colorants in customary amounts. furthermore, the
resin compositions can if desired also comprise fillers and/or
pigments in customary amounts.
[0102] Using the Resin Compositions
[0103] The impregnating, casting and coating compositions of the
invention are applied by the processes, widely known in electrical
engineering, of dip impregnation, the trickle technique, the
dip-rolling technique, the flooding technique and the process of
casting for the impregnation of windings or the like. Details of
these techniques are as follows:
[0104] the impregnation of the substrate that is to be impregnated,
and which may have been preheated, takes place in general by
dipping it into the liquid resin composition (A), leaving the
substrate that is to be impregnated in the resin composition for a
time, until the resin composition has reached all areas to be
impregnated and, possibly, until the resin that has penetrated the
substrate gels, emersing the impregnated substrate and allowing it
to drip dry, and then curing the resin composition (A) that has
been taken up.
[0105] The trickling of the resin composition (A) onto the
substrate that is to be impregnated takes place by trickling the
resin composition (A) onto the substrate, which may have been
preheated, by means of appropriate pumps, (A3) if desired and (A6)
if desired being metered in by means of suitable mix-metering
devices prior to the trickle application of the resin composition
(A1) or the resin composition (A) being activated already
beforehand by addition of the hardener (A3).
[0106] Flooding with the resin composition (A) takes place by
causing a rising bath of the resin composition (A) to flood the
optionally preheated substrate in such a way that sufficient
impregnation of the substrate takes place, then leaving the resin
composition (A), possibly until the resin that has penetrated the
substrate has gelled, allowing the substrate to drip dry, and then
curing the resin composition (A) that has been taken up by the
substrate.
[0107] Dip-rolling with the resin composition (A) takes place by
the optionally preheated substrate being rolled through the
activated resin composition (A) in such a way that, in the case of
windings of electrical machines as substrate, only the winding and
the winding-bearing part of the susbtrate are covered by the resin
composition (A), until the winding has been sufficiently
impregnated, and then curing the resin composition that has been
taken up by the substrate (by the winding), preferably with
rotation.
[0108] The casting of the substrates in a reusable or consumed
mould with a preactivated resin composition (A) or, using an
appropriate mix-metering system, by admixing (A4) if desired and
(A6) if desired, directly prior to casting.
[0109] To improve the quality of impregnation, the impregnating
technique set out above can preferably be conducted under vacuum or
else in alternation between vacuum and overpressure.
[0110] The preheating of the substrate can be carried out, for
example, by means of Joule heat (heating by electrical resistance),
induction heating, microwave or infrared heating and by passing
them through a conventional thermal oven.
[0111] The resin composition which adheres to the substrate
following impregnation can be cured thermally: for example, in the
case where the substrates are preheated, by means of Joule heat,
induction heating, microwave or infrared heating and by passage
through a conventional thermal oven, or by means of high-energy
radiation, examples being UV radiation or electron beams.
Preference, however, is given to a combination of thermal curing
and radiative curing, it being possible to carry out both cures
simultaneously or in any desired order of supply of energy. The
inner regions of the components are cured preferably either by
further supply of current and/or by post-curing in the oven, and
curing on the substrate surface is preferably assisted by
additional irradiation; for example, IR, UV or electron beams.
[0112] The examples which follow are intended to illustrate the
invention further. All percentages relate, unless stated otherwise,
to percent by weight.
EXAMPLES
Example 1
[0113] Preparing an Unsaturated Polyester Resin (A1-1)
[0114] 312 g of neopentyl glycol (3.0 mol) and 125 g of propylene
glycol (1.2 mol) are heated to to [sic] 140.degree. C. under
nitrogen in a customary laboratory stirred apparatus, 332 g of
isophthalic acid (2.0 mol) are added in portions, and then the
mixture is heated at 180.degree. C. with distillative removal of
the water of condensation in 2 hours. It is then cooled to
120.degree. C., 232 g of maleic anhydride (2.0 mol) are added, and
the mixture is heated in 2 hours to 200.RTM. C., with a vacuum
being applied in the last 30 minutes. The resulting melt is cast
onto aluminium foil and soldifies to give a resin having an acid
number of 17 mg of KOH/g.
Example 2
[0115] Preparing a Component (A3-1)
[0116] 1586.52 g of dicyclopentadiene (12.0 mol) and 1176.72 g of
maleic anhydride (12.0 mol) are weighed out into a stirred flask
with heater and reflux condenser. The mixture is heated to
125.degree. C. under a gentle stream of nitrogen, and then 226.00 g
of water (12.0 mol+10 g) are added by way of a dropping funnel in 1
hour. The mixture is allowed to react at 125.degree. C. for one
hour. A reaction mixture is obtained comprising predominantly a
monocarboxylic acid of the formula (V). The contents of the flask
are cooled to 70.degree. C., and then 715.00 g of 1,6-hexanediol
(6.05 mol), 4.00 g of dibutyltin dilaurate (DBTL) and 0.50 g of
hydroquinone are added.
[0117] The mixture is rapidly heated to 120.degree. C. under a
gentle stream of nitrogen. Then, over 6 hours, the temperature is
gradually raised to 190.degree. C., during which the water of
condensation that forms is removed by distillation. A viscous resin
is obtained which has an acid number of 24 mg of KOH/g and a
viscosity of 3650 mPas at 50.degree. C.
Example 3
[0118] Preparing a Component (A3-2)
[0119] 661.10 g of dicyclopentadiene (5.0 mol) and 490.30 g of
maleic anhydride (5.0 mol) are weighed out into a stirred flask
with heater and reflux condenser. The mixture is heated to
125.degree. C. under a gentle stream of nitrogen, and then 95.00 g
of water (5.0 mol+5 g) are added by way of a dropping funnel in one
hour. The mixture is allowed to react at 125.degree. C. for one
hour. The result is a reaction mixture comprising predominantly a
monocarboxylic acid of the formula (V). The contents of the flask
are cooled to 70.degree. C., and then 1859.00 g of TP 200 (5.5
mol-equivalent --OH), 3.00 g of dibutyltin dilaurate (DBTL) and
0.30 g of hydroquinone are added. TP 200 is an ethoxylation product
of 1 mol trimethylolpropane and 20 mol of ethylene oxide.
Esterification is carried out as in Example 2 to give a viscous,
liquid resin having an acid number of 21 mg of KOH/g and a
viscosity of 9340 mPa.multidot.s at 25.degree. C. and of 1560
mPa.multidot.s at 75.degree. C.
Example 4
[0120] Preparing an Unsaturated Polyester Resin (A1-2)
[0121] 661.10 g of dicyclopentadiene (5.0 mol) and 490.30 g of
maleic anhydride (5.0 mol) are weighed out into a stirred flask
with heater and reflux condenser. The mixture is heated to
125.degree. C. under a gentle stream of nitrogen, and then 95.00 g
of water (5.0 mol+5 g) are added by way of a dropping funnel in 1
hour. The mixture is allowed to react at 125.degree. C. for one
hour. A monocarboxylic acid of formula (V) is formed. The contents
of the flask are cooled to 70.degree. C., and then 245.15 g of
maleic anhydride (2.5 mol), 116.00 g of fumaric acid (1.0 mol),
272.70 g of neopentyl glycol (2.5 mol), 413.20 g of 1,6-hexanediol
(3.5 mol), 4.00 g of dibutyltin dilaurate (DBTL) and 0.50 g of
hydroquinone are added.
[0122] The mixture is rapidly heated to 120.degree. C. under a
gentle stream of nitrogen. Then, over 3 hours, the temperature is
gradually raised to 190.degree. C., and the water of condensation
that forms is removed by distillation. After a further 3 h, the
condensation is terminated. The result is a liquid resin having an
acid number of 31 mg of KOH/g and a viscosity of 32,350 mPas at
25.degree. C.
Example 5
[0123] Preparing an Unsaturated Polyester Resin (A1-3)
[0124] 661.10 g of dicyclopentadiene (5.0 mol) and 490.30 g of
maleic anhydride (5.0 mol) are weighed out into a stirred flask
with heater and reflux condenser. The mixture is heated to
125.degree. C. under a gentle stream of nitrogen, and then 95.00 g
of water (5.0 mol+5 g) are added by way of a dropping funnel in one
hour. The mixture is allowed to react at 125.degree. C. for 1 hour.
The result is a reaction mixture comprising predominantly a
monocarboxylic acid of formula (V). The contents of the flask are
cooled to 70.degree. C., and then 245.15 g of maleic anhydride (2.5
mol), 116.00 g of fumaric acid (1.0 mol), 272.70 g of neopentyl
glycol (2.5 mol), 436.60 g of 1,6-hexanediol (3.7 mol), 4.00 g of
dibutyltin dilaurate (DBTL) and 0.50 g of hydroquinone are
added.
[0125] The mixture is rapidly heated to 120.degree. C. under a
gentle stream of nitrogen. Then, over 3 hours, the temperature is
gradually raised to 190.degree. C., and the water of condensation
that forms is removed by distillation. After a further 3 h, the
condensation is terminated and the batch is left to cool to
70.degree. C. The result is a liquid resin having an acid number of
18 mg of KOH/g and a viscosity of 16,880 mPas at 25.degree. C. To
the hot resin there are added 64.40 g of
benzophenonetetracarboxylic dianhydride (0.20 mol), 70.00 g of
gycidyl [sic] methacrylate (0.50 mol) and 10.00 g of
triphenylphosphine as catalyst. The temperature is raised to
105.degree. C. and maintained for 2.5 h. Then the mixture is
cooled. The result is a liquid resin having an acid number of 11 mg
of KOH/g and a viscosity of 53,650 mPas at 25.degree. C.
Example 6
[0126] Preparing an Unsaturated Polyester Resin (A1-4)
[0127] 245.15 g of maleic anhydride (2.5 mol), 290.00 g of fumaric
acid (2.5 mol), 272.70 g of neopentyl glycol (2.5 mol), 107.00 g of
trimethylolpropane monoallyl ether (0.5 mol), 87.00 g of
trimethylolpropane diallyl ether (0.5 mol), 206.50 g of
1,6-hexanediol (1.75 mol), 4.00 g of dibutyltin dilaurate (DBTL)
and 0.50 g of hydroquinone are weighed out into a stirred flask
with heater and reflux condenser. The mixture is heated rapidly to
120.degree. C. under a gentle stream of nitrogen. Then, over 3
hours, the temperature is gradually raised to 190.degree. C.,
during which the water of condensation that forms is removed by
distillation. After a further 3 h the condensation is terminated.
The result is a liquid resin having an acid number of 32 mg of
KOH/g and a viscosity of 36,750 mPas at 25.degree. C.
Example 7
[0128] Curing Experiments
[0129] The substances of Examples 1 to 6 are used to prepare liquid
compositions (M1 to M6) which can be cured both thermally and with
UV light. For this purpose the resin compositions are weighed out
into closeable bottles, heated to about 50.degree. C. in a drying
oven and mixed with a glass rod. After cooling, the curing
accelerators are added, the bottles are sealed and the mixtures are
homogenized overnight on a roller bed. This results in slightly
viscous, clear, homogeneous resin formulations.
1TABLE 1 Composition and viscosity of the resin compositions M1 to
M6 M1 M2 M3 M4 M5 M6 A1-1 100 100 -- -- -- -- A1-2 -- -- -- -- 100
100 A1-3 -- -- 100 -- -- -- A1-4 -- -- 10 100 -- -- A3-1 20 -- --
-- -- -- A3-2 -- 15 15 20 20 -- P-490 35 35 35 35 35 35 TBPB 2 2 2
2 2 2 BDK 3 3 -- 3 3 3 Visc. 4140 2950 2680 3360 2840 3070
[0130] Key to Table 1:
[0131] A1-1 to A1-4 and A3-1 and A3-2 are the above-described
resins of Examples 1 to 6
[0132] P-490 is an experimental product of the company BASF AG,
Ludwigshafen, a polytetrahydrofuran divinyl ether (vinylation
product of polytetrahydrofuran) having a viscosity of 21
mPa.multidot.s at 25.degree. C. and an average molecular weight of
about 490, and corresponds to the legal definition of "polymer"
(cf. EU Official Journal of 5.6.92, No. L 154/3)
[0133] TBPB is tert-butyl perbenzoate (peroxide catalyst)
[0134] BDK is benzil dimethyl ketal (photoinitiator)
[0135] Visc. is the viscosity of the resin compositions M1 to M6 at
25.degree. C. in mPa.multidot.s
[0136] 65 g of each of the resin compositions M1 to M6 are
introduced into metal lids of 60 mm in diameter, are heated to
80.degree. C. on a thermostated hot plate and are exposed with a
mercury vapour lamp for 3 min at this temperature. The lamp has a
radiation maximum at about 360 nm and at the height of the sample
surface supplies an energy of 21 mW/cm.sup.2. After exposure, a
tack-free skin beneath which there is still liquid resin has formed
on all samples. The metal lids are then after-cured at 130.degree.
C. in a drying oven for 2 hours. This results in light-brownish,
hard, crack-free, clear resin blocks. The resins blocks are
back-weighed in order to determine the curing emissions. For all
samples these emissions are below 0.5%.
[0137] A second series of samples was exposed at 90.degree. C. for
25 min. Thereafter, all of the samples had undergone complete
through-curing, and for all samples the curing emissions were below
0.25%.
* * * * *