Note: Descriptions are shown in the official language in which they were submitted.
1 15S863
-- 1 --
3-11498/1-5/D
CANADA
Sensitizers for_photopolymerisation
The invention relates to the use of aromatic
aliphatic ketones which are substituted in the ~-position
as sensitizers for the photopolymerisation of unsaturated
compounds or for the photochemical crosslinking of poly-
olefins, as well as to the photopolymerisable and cross-
linkable systems which contain such sensitizers.
Photochemical polymerisation processes have
attained substantial importance in the art, especially in
those cases where thin layers have to be hardened in a
short time, for example in the hardening of varnish coat-
ings or in the drying of printing inks. Compared with con-
ventional hardening methods, UV irradiation in the presence
of photosensitizers has a number of advantages, the most
important of which is the great speed of the photohardening.
The speed is heavily dependent on the photosensitizer em-
ployed and there has been no lack of attempts to replace
the conventional sensitizers by ever better and more effec-
tive compounds. Among the most effective photosensitizers
are derivatives of benzoin, in particular the benzoin
esters described for example in German patent specification
Al ~
1~5~63
1,694,149, derivatives of ~-hydroxymethylbenzoin described
in German Offenlegungsschrift 1,923,266, and the dialkoxy-
acetophenones and benzil monoketals described for example
in German Offenlegungsschrift 2,261,383 or 2,232,365.
~-Aminoacetophenones and ~-diaminoacetophenones have re-
cently been proposed as photosensitizers in US patent speci-
fication 4,04~,034and a-hydroxy-a-alkylolacetophenones and
their ethers in German Offenlegungsschrift 2,357,866. The
shortcomings of these known photosensitizers are in some
cases an insufficient storage life in the dark of the photo-
polymerisable systems mixed with such sensitizers. A number
of benzoin derivatives tend to cause yellowing of the har-
dened compositions. Other sensitizers are insufficiently reac-
tive - a feature which is observed in the relatively lengthy
hardening times - or their solubility in the photopolymeri-
sable systems is too low or they are rapidly rendered in-
active by atmospheric oxygen. There is therefore a need in
the art for photosensitizers which are readily soluble in
the substrate and, while having a good storage life in the
dark, initiate the photopolymerisation more rapidly and
give a higher polymer yield per unit of time than the known
photosensitizers. By using such improved photosensitizers
it would be possible to exploit better the expensive in-
dustrial UV irradiation plants.
It has been found that compounds of the follow-
ing formula I possess the required properties as photo-
sensitizers. In particular, they effect a rapid photo-
polymerisation and do not have the shortcomings referred
to or possess them to a much lesser degree than the known
photosensitizers. Furthermore, they are suitable for
the photochemical crosslinking of polyolefins. The
invention relates to a compound of the formula I,
1 15S863
Rl O O R
11 11
X - C - C - Ar - C - C - X (I)
R2 R2
wherein Ar represents arylene of 6 to 12 carbon atoms or
a phenylene-T-phenylene group, wherein T represents
-O-, -S-, -SO2-, -CH2- or -CH=CH-, X represents -NR R ,
OR , -O-Si(R )(R7)2, hydroxymethoxy, (Cl-C4 alkoxy)methoxy,
(C2-C8 acyloxy)methoxy or together with Rl represents
(C C alkyl)-O(CH2)1 2-' -OCH(C6 C14 y
OCH(Cl-C8 alkyl)- or -OCH(C6-C14 aryl)-, R represents
alkyl of 1 to 8 carbon atoms optionally substituted by OH,
Cl-C4 alkXY~ C2-C8 aCyloxy~ ~Coo-(cl-c4)alkyl or -CN,
or represents cycloalkyl of 5 to 6 carbon atoms or phenyl-
alkyl of 7 to 9 carbon atoms, R2 has one of the meanings
assigned to Rl or represents allyl, methallyl, 2-carbamoyl-
ethyl, 2-(N-Cl-C4 alkylcarbamoyl)ethyl, 2-(N,N-di-Cl-C4
alkylcarbamoyl)ethyl, 2-(2-pyridyl)ethyl, 2-l2-oxo-1-
pyrrolidinyl)ethyl or 2-(di-O-Cl-C4 alkylphosphono)ethyl,
or R and R together represent alkylene of 4 to 6 carbon
atoms or oxaalkylene or azaalkylene of 3 to 4 carbon
atoms, or R and R are both hydroxymethyl, R3 represents
hydrogen, alkyl of 1 to 12 carbon atoms, alkyl of 2 to 4
carbon atoms which is substituted by -OH or -Oalk, or
represents allyl, cyclohexyl, phenylalkyl of 7 to 9 carbon
atoms, phenyl or phenyl which is substituted by Cl or
alk, R4 represents alkyl of 1 to 12 carbon atoms, alkyl
of 2 to 4 carbon atoms which is substituted by -OH or
-Oalk, or represents allyl, cyclohexyl, phenylalkyl of
7 to 9 carbon atoms, phenyl or phenyl which is substituted
by Cl, alk, OH~ -Oalk or -COOalk, wherein alk is a lower
alkyl radical of 1 to 4 carbon atoms, R represents alkyl
1 15$863
of l to 12 carbon atoms, alkyl of 2 to 4 carbon atoms
which is substituted by -OH or -Oalk, or represents
allyl, cyclohexyl or phenylalkyl of 7 to 9 carbon atoms,
or together with R represents alkylene of 4 to 5 carbon
atoms which can be interrupted by -O-, -NH- or -Nalk-, or
together with R2 represents alkylene or phenylalkylene
of 1 to 9 carbon atoms or oxaalkylene or azaalkylene
of 2 to 3 carbon atoms, and R6 and R7 are the same or
different and represent alkyl of l to 4 carbon atoms or
phenyl.
Of the substituents listed above, Rl and R
can be alkyl of l to 8 carbon atoms, for example methyl,
ethyl, propyl, butyl, hexyl or octyl. R4 and R as alkyl
can be unbranched or branched alkyl of 1 to 12 carbon
atoms, for example methyl, ethyl, isopropyl, tert.-buty],
isoamyl, n-hexyl, 2-ethylhexyl, n-decyl or n-dodecyl.
Alk represents a lower alkyl radical of 1 to 4 carbon
atoms, for example methyl, ethyl, isopropyl, n-butyl
or tert.-butyl.
Rl and R2 as hydroxyalkyl, alkoxyalkyl or acyl-
oxyalkyl can be for example hydroxymethyl, l-hydroxy-
ethyl, 2-hydroxyethyl, 2-isopropoxyethyl, l-hydroxyiso-
butyl, l-acetyloxybutyl, l-acryloyloxyhexyl, l-hydroxy-
octyl, 3-benzoyloxypropyl, methoxymethyl or isobutyloxy-
methyl. The acyl radical can be the radical of an aliphatic
or aromatic carboxylic acid. Preferably they are l-hydroxy-
alkyl radicals and their ethers or esters. R , R4 and R
as hydroxyalkyl or alkoxyalkyl can be for example 2-
hydroxyethyl, 2-butoxyethyl, 2-methoxypropyl, 3-hydroxy-
propyl or 2-ethoxybutyl. Preferably they are 2-hydroxy-
alkyl radicals and the ethers thereof.
R and R2 as CN-substituted alkyl can be for
115~863
example 2-cyanoethyl, 2-cyanopropyl, 4-cyanobutyl, cyano-
methyl, 2-cyanohexyl or 4-cyanooctyl. The 2-cyanoethyl
radical is preferred.
R and R2 as alkyl substituted by -COOalk can
be for example -CH2COOC2H5, -CH2CH2COOCH3, -(CH2)3-
COOCH3 or -CH2-CH(C2H5)-COOC4Hg.
R and R as cycloalkyl can be cyclopentyl or
cyclohexyl. Rl, R , R3, R and R as phenylalkyl can be
for example benzyl, phenylethyl or dimethylbenzyl.
R and R together can represent alkylene or oxa-
alkylene or azaalkylene. In this case, Rl and R together
with the carbon atom to which they are attached form a
cyclopropane, cyclobutane, cyclopentane, cyclohexane,
cycloheptane, tetrahydrofurane, tetrahydropyrane, pyrroli-
dine or piperidine ring.
R2 and R together can represent alkylene or
phenylalkylene of 1 to 9 carbon atoms or oxaalkylene or
azaalkylene. In this case, R2 and R5 together with the
carbon atom to which R is attached and the nitrogen atom
to which R is attached form a 3- to 6-membered ring, for
example an aziridine, azetidine, pyrrolidine, imidaz-
olidine, piperidine, piperazine or morpholine ring.
R4 and R5 together can represent alkylene of
4 to 5 carbon atoms which can be interrupted by -O- or
-NR14-. In this case, R4 and R5 together with the nitrogen
atom to which they are attached form a pyrrolidine, piperi-
dine, morpholine, 4-alkylpiperazine, 4-cyanoethyl-
piperazine or 4-alkoxycarbonylethylpiperazine ring.
,~ '';
~1SS863
6 --
X and R together can represent a -OC~I(Cl-C8
Y ~ 2)1-2 ~ OCH(C6-C14 aryl)-O-(CH2)1 2-~ -OCH-
(Cl-C8 alkyl)- or -OCH(C6-C14 aryl)-group. In this
case, R and X together with the carbon atom to which they
are attached form an oxirane, oxetane, oxolane, tetrahydro-
pyrane, 1,3-dioxolane or 1,3-dioxane ring which can be
substituted by alkyl or aryl.
Ar can be arylene of 6 to 12 carbon atoms, for
example phenylene, naphthylene or diphenylene.
Examples of compounds of the formula I are:
4,4'-bis-(a-hydroxy-isobutyryl~-diphenyl oxide, 4,4'-bis-
(a-hydroxy-isobutyryl)-diphenyl, 4,4'-bis-(a-hydroxy-
-isobutyryl)-diphenyl sulfide, 4,4'-bis-(a-hydroxy-iso-
butyryl)-diphenyl methane, 4,4'-bis-(a-piperidino-iso-
butyryl)-diphenyl oxide, 4,4'-bis-[a-(isopropylamino)-
isobutyryl]-diphenyl, 4,4'-bis-(a-benzoyloxy-isobutyryl)-
diphenyl. oxide, 4,4'-bis-(a-hydroxy-isobutyryl)-diphenyl
ethene~
~ he compounds of the formula I can be prepared
from aromatic-aliphatic ketones by the following reaction
steps:
Ar [CO-CHR R ]2 ~ Ar--~CO-CBrR R ]2
~ C33 12 ~ R 2
~5863
-- 7 --
~ s HX it is possible to use amines [C.L. Stevens,
Ch. Hung Chang, J. Org. Chem. 27 (1962), 4392] or water or
carboxylic acids [C.L. Stevens, E. Farkas, J. Am. Chem. Soc.
74 (1952), 618 and C.L. Stevens, S.J. Dykstra, J. Am. Chem.
Soc. 75 (1953), 5976].
In many cases the direct reaction of the ~-bromo-
ketones to give compounds of the formula I
O Rl
Ar ~ CO CBrRl~ ] ~ Ar ~ C - C- X ]
is also possible, for example with amines, alkali hydroxides
or alkali phenoxides. Instead of bromine compounds it is
also possible to use the corresponding chlorine compounds.
The resulting hydroxyketones of the formula I
(X=OH) can be etherified or O-silylated by the conventional
methods.
Compounds of the formula I, wherein R is a sub-
stituted alkyl group, can be obtained from the compounds
of the formula Ar-~CO-CH(R )-X]2 by reaction with aldehydes
(Rl = hydroxyalkyl) or with a vinyl compound which is cap-
able of addition, for example with acrylates or acrylonit-
rile. If both R and R are substituted alkyl, then both
substituents can be introduced jointly by reaction of a
compound Ar-~CO-CH2-X]2 with at least 2 moles of an aldehyde
or a vinyl compound. The corresponding alkoxyalkyl and acyl-
oxyalkyl groups can be obtained from the hydroxyalkyl groups
R and/or R by etherification or esterification.
11S5863
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According to the invention, the compounds of the
formula I can be used as sensitizers for the photopoly-
merisation of unsaturated compounds or systems which contain
such compounds.
Such compounds are for example unsaturated mono-
mers, such as esters of acrylic or methacrylic acid, for
example methylacrylate, ethylacrylate, n- or tert-butyl-
acrylate, isooctylacrylate or hydroxyethylacrylate, methyl-
or ethylmethacrylate, ethylene diacrylate, neopentyl dia-
crylate, trimethylolpropane trisacrylate, pentaerythritol
tetraacrylate or pentaerythritol trisacrylate; acrylo-
nitrile, methacrylonitrile, acrylamide, methacrylamide,
N-substituted acrylamides and methacrylamides; vinyl esters,
such as vinyl acetate, vinyl propionate, vinyl acrylate or
vinyl succinate; other vinyl compounds, such as vinyl
ethers, styrene, alkyl styrenes, halostyrenes, divinyl
benzene, vinyl naphthalene, N-vinylpyrrolidone, vinyl
chloride or vinylidene chloride; allyl compounds, such as
diallyl phthalate, diallyl maleate, triallyl isocyanurate,
triallyl phosphate or ethylene glycol diallyl ether and the
mixtures of such unsaturated monomers.
Photopolymerisable compounds are in addition un-
saturated oligomers or polymers and the mixtures thereof
with unsaturated monomers. These include thermoplastic
resins which contain unsaturated groups, such as fumaric
acid ester groups, allyl groups or acrylate or methacrylate
groups. These unsaturated groups are usually bound through
functional groups to the main chain of these linear poly-
mers. Mixtures of oligomers with simply and poly-unsaturated
monomers are very important. Example~ of such oligomers are
unsaturated polyesters, unsaturated acrylic resins and iso-
,,,~ ~;,,
,", ~,,,
~155~63
cyanate or epoxide modified acrylate oligomers as well aspolyether acrylate oligomers. Examples of poly-unsaturated
compounds are in particular the acrylates of diols and poly-
ols, for example hexamethylene diacrylate or pentaerythri-
tol tetracrylate. Acrylates are also preferred as simply
unsaturated monomers, for example butyl acrylate, phenyl
acrylate, benzyl acrylate, 2-ethylhexyl acrylate or 2-
hydroxypropyl acrylate. By choosing from the different
representatives of the three components, the opportunity
is afforded to vary the consistency of the unpolymerised
mixture as well as the plasticity of the polymerised resin.
In addition to these three-component mixtures,
two-component mixtures especially are of great importance
among the polyester resins. These usually consist of an un-
saturated polyester and a vinyl compound. The unsaturated
polyesters are oligomer esterification products of at least
one unsaturated dicarboxylic acid, for example maleic,
fumaric or citraconic acid, and usually of at least one
saturated dicarboxylic acid, for example phthalic acid,
succinic acid, sebacic acid or isophthalic acid, with
glycols, for example ethylene glycol, propanediol-1,2,
di- or triethylene glycol or tetramethylene glycol r whilst
monocarboxylic acids and monoalcohols are generally also
used concurrently for the modification. These unsaturated
polyesters are normally dissolved in a vinyl or allyl com-
pound, styrene being preferably used for this purpose.
Photopolymerisable systems which are used for
the different purposes usually contain, in addition to the
photopolymerisable compounds and the photosensitizer, a
number of other ingredients. It is therefore often customary
to add heat inhibitors in order to prever,t a premature poly-
merisation, especially during the preparation of the systems
11S5863
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by mixing the components. E~ydroquinone, llydroquinone deriva-
tives, p-methoxyphenyl, ~-naphthylamine or ~-naphthols are
used for example for this purpose. Furthermore, small
amounts of UV absorbers can be added, for example those of
the benztriazole or benzophenone type.
To increase the storage life in the dark, it is
possible to add copper compounds, such as copper naphthenate,
copper stearate or copper octoate, phosphorus compounds,
such as triphenylphosphine, tributylphosphine, triethyl
phosphite, triphenyl phosphite or tribenzyl phosphate,
quaternary ammonium compounds, such as tetramethylammonium
chloride or, trimethylbenzylammonium chloride, or hydroxyl-
amine derivatives, for example N-diethylhydroxylamine. In
addition, the photopolymerisable systems can contain chain
transfer agents, for example N-methyl-diethanolamine, tri-
ethanolamine or cyclohexene.
In order to exclude the inhibiting action of
atmospheric oxygen, paraffin or similar wax-like substances
are frequently added to photohardening systems. On account
of their poor solubility in the polymer, these substances
float at the beginning of the polymerisation and form a
transparent surface layer which prevents the entry of air.
The atmospheric oxygen can also be deactivated by introduc-
ing autoxidisable groups, for example allyl groups, into
the resin to be hardened.
Depending on the end-use, photopolymerisable
systems also contain fillers, such as silicic acid, talc or
gypsum, pigments, dyes, fibres, thixotropic agents or level-
ling agents.
1155863
11 -
Combinations with known photosensitizers, such as
benzoin ethers, dialkoxy acetophenones or benzyl ketals,
can also be used. Combinations of the photosensitizers of
the invention with amines and/or aromatic ketones can be
used especially for the photopolymerisation of thin layers
and printing inks. Examples of amines are triethylamine,
N-methyldiethanolamine, N-dimethylethanolamine or p-di-
methylaminobenzoate. Examples of ketones are benzophenone,
substituted benzophenone derivatives, Michler's ketone,
anthraquinone and anthraquinone derivatives, as well as
thioxanthone and the derivatives thereof.
Photohardening is of great importance for print-
ing inks, since the drying time of the binder is a decisive
factor in the production speed of printing products and
should be in the order of fractions of seconds. The sensi-
tizers of the invention are also very suitable for photo-
hardening systems for the manufacture of printing plates.
Mixtures of soluble linear polyamides with photopolymeris-
able monomers, for example acrylamides, and a photosensi-
tizer, are usually employed for this purpose~ Films or
plates prepared from these systems are exposed vla the
negative (or positive) of the original and the unhardened
portions are subsequently eluted with a solvent.
A further field of use of UV hardening is metal
coating, for example in the varnish coating of metal sheeting
for tubes, cans or bottle caps, as well as the UV hardening
of plastic coatings, for example of floor or wall coverings
based on PVC.
Exemplary of the UV hardening of paper coatings
is the colourless varnish coating of labels, gramophone
1 155863
record sleeves or book jackets.
According to the invention, the compounds of the
formula I can also be used as sensitizers
for the photochemical crosslinking of polyolefins, for
example polypropylene, polybutene, polyisobutylene and also
copolymers, for example ethylene/propylene copolymers, but
preferably polyethylene of low, medium or high density.
The photosensitizers are advantageously used for
the above fields of use in amounts of 0.1 to 20% by weight,
preferably about 0.5 to 5% by weight, based on the photo-
polymerisable or crosslinkable system. The term "system"
is to be understood as meaning the mixture of the photo-
polymerisable or crosslinkable compound, the photosensitizer
and the other fillers and additives, as it is used in the
respective application.
The addition of the photosensitizers to the photo-
polymerisable systems is accomplished in general by simple
stirring, since most of these systems are fluid or readily
soluble. Usually the sensitizers of the invention dissolve
in the system, thereby ensuring their uniform distribution
and the transparency of the polymers.
The polymerisation is carried out by the known
methods of polymerisation by irradiation with light which
is rich in shortwave radiation. Suitable light sources are
for example mercury medium pressure, high pressure and low
pressure lamps, as well as superactinic fluorescent tubes,
the emission peaks of which are in the range between 250
and 400 nm.
863
- 13 -
The following Examples describe the manufacture
and use of compounds of the formula I in more detail. Parts
and percentages are by weight.
Example l: Manufacture and properties of the compounds of
formula I
The compounds listed in Table l were obtained by
one or more of the methods A to K.
Method_ A Chlorination of aromatic-aliphatic ketones
Ar~C0-CR R H]n + n Cl2 _ Ar~C0-CR R Cl]n + n HCl
The ketone is dissolved in an inert solvent, preferably in
tetrachloromethane, and the calculated amount of chlorine
is introduced into the solution at 40-80C. Nitrogen is
then introduced to remove dissolved HCl. Finally, the sol-
vent is distilled off. Purification of the chloroketone is
usually not necessary and the product can subsequently be
reacted by method D, F or H.
Method B Bromination of aromatic-aliphatic ketones
Ar~CO-CRlR2H]n + n Br2 ~--~Ar~C0-CR R Br3n + n HBr
The calculated amount of bromine is added dropwise at room
temperature to a solution of the ketone, for example in
CCl4. Working up and further processing are effected as in
Method A.
Method C Chlorination with sulfuryl chloride
1 15S863
- 14 -
Ar~CO-CRlR2H~ 2 C12 ~ Ar~CO-CRlR--Cl]n
+ n S02 ~ n HCl
The sulfuryl chloride is added dropwise at 40C to a solu-
tion of the ketone in CC14. Working up and further process-
ing as in Method A.
Method D ~reparation of the epoxide intermediate
Ar~CO-CRlR Hal] n + n NaOCH3 -~ArfC - CR R ] n + n NaHal
OCH3
Hal = Cl or Br
The haloketone is dissolved in methanol and a solution of
the stoichiometric amount of sodium methoxide in methanol
is added dropwise at reflux temperature. The methanol is
then distilled off and the residue is poured into ice-water
and extracted with ether. The ethereal solution is washed
with water, dried over Na2S04, dried and concentrated. The
residue is purified by recrystallisation or vacuum distil-
lation. The epoxide can subsequently be reacted bv Method E
or G.
Method E Hydrolysis of the epoxide
1 .
Ar ~C \CRlR2~ + n H20 H ~ Ar~co-cRlR2oH] +n CH30H
OCH3
The epoxide is covered with 2 to 5 times its weight of water
and the mixture is refluxed for 1 to 2 hours with the addi-
tion of a catalytic amount of mineral acid. After cooling,
the reaction mixture is extracted with ether. The ethereal
1 155863
- 15 -
solution is washed with water, dried over Na2S04, and con-
centrated. The residue (crude hydroxyke,one) is purified
by distillation or crystallisation or column chromatography.
The properties of the pure a-hydroxyketones are indicated
in Table 1.
Method F a-Hydroxyketones from a-haloketones
Ar~CO-CR R Hal~n + n NaOH _ Ar~CO-CR R OH]n + n NaHal
The a-haloketone is refluxed in dilute or concentrated
sodium hydroxide solution (20% excess of NaOH~. When the
hydrolysis is complete (check by chromatography), the crude
hydroxyketone is isolated and purified as described in
Method E. The pure hydroxyketones are listed in Table 1.
Method G a-Aminoketones from the epoxides
Ar~C - CRlR ] n +n R R5NH ~ Ar~CO-CRlR2-~R4R5] +n CH30H
OCH3
, _
The epoxide is treated with the stoichiometric amount of the
amine, either without a solvent or with the addition of a
small amount of toluene or xylene, and reacted for about
10 to 20 hours at 100-200C. When using low boiling amines,
for example dimethylamine or diethylamine, the reaction is
carried out in an autoclave. The reaction mixture is diluted
with benzene and extracted with dilute hydrochloric acid.
The aqueous acid solution is made alkaline with NaOH and
extracted with ether. The ethereal solution is washed with
water, dried over Na2S04 and concentrated. The crude product
is purified by distillation or crystallisation. The a-amine-
ketones are listed in Table 1.
}'~",'
1 155863
- 16 -
Method_H ~-Aminoketones from the ~-halo~etones
Ar~CO-CR R Hal] + 2n R R NH ~ Ar~CO-CR R -NR R ] n
4 5
+ n R R NH2Hal
The ~-haloketone, undiluted or diluted with toluene, is
mixed with 2 molar equivalents of the amine and the mixture
is heated for 10 to 20 hours to 100-200C. When using low
boiling amines, for example dimethylamine or diethylamine,
the reaction is carried out in an autoclave. Isolation and
purification are effected as in Method G.
Method I Introduction of a carbalkoxyethyl group
CH2CH2CAlk
Ar~CO-CHR -X]n + n CH2 = CH-COOAlk _ Ar~CO-CRl-X ] n
The ketone is dissolved in dimethyl sulfoxide. To the solu-
tion are then added 1.1 molar equivalents of NaOH in the
form of 4N sodium hydroxide solution and, with cooling,
1.1 molar equivalents of acrylate are added dropwise at
room temperature. The reaction mixture is diluted with ice-
water and extracted with toluene. The toluene solution is
washed neutral with water, dried over Na2S04 and concentra-
ted. The crude product is purified by column chromatography
or crystallisation.
Method K Etherification of hydroxyketones
Ar~CO-CRlR -OH] + n R Hal + n NaOH Ar~CO-CR R -OR ]n
+ n NaHal
1 1558~3
- 17 -
The ~-hydroxyketone is dissolved in about 4 times its weight
of dimethyl sulfoxide and, while cooling to 10-20C and
with stirring, 1 molar equivalent of the alkyl halide R6Hal
and 1 molar equivalent of concentrated sodium hydroxide
solution are added dropwise simultaneously from two drip
funnels. The reaction mixture is then stirred for 3 hours
at room temperature. Precipitated sodium halide is then
removed by filtration, the filtrate is washed with water,
dried over Na2S04 and concentrated. The crude product is
purified by column chromatography, crystallisation or
vacuum distillation. Examples of eligible halogen compounds
are methyl iodide, isopropyl bromide, allyl bromide, cyclo-
hexyl bromide, benzyl chloride or ethyl chloroacetate.
Instead of using an alkyl halide, it is also possible to use
a dialkyl sulfate or alkylaryl sulfonate as etherifying
reagent.
1 1SS863
-- 18 --
~ .
_ O o
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rl ~ O
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~ O Q~ X
P-~ R 3 e
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V V V :~
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o=y o= C~
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o=~ o= '
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E~
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,h
1 1~5863
-- 19 --
Example 2: Use as photoinitiator
A resin mixture consisting of 70 parts of Ebercyl
593 (polyester acrylate available from UCB, Belgium), 30
parts of trimethylolpropane trisacrylate, O.S part of ByK
300 ~levelling assistant available from ByK-Mallinchrodt,
West Germany) and 3 parts of the compound No. l, is
applied to glass plates in a layer of 30 - 40,u. After
brief exposure to air, hardening is effected with a UV
laboratory device (model PPG/QC-processer) with a UV
lamp of 80 watts/cm. After the UV hardening, the plates are
stored for 1/2 hour under normal climatic conditions and
then the hardness of the layers is determined using the
pendulum device of Konig. If the conveyor belt in the
irradiation device has a transpo~tation speed ad 10 m/min
the film sample showed a pendulum hardness of 155 sec.
At a speed of 25 m/min the pendulum hardness is 143 sec.
