Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2001-01-08
2002-08-20
Berman, Susan W. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S173000, C560S115000, C560S205000, C560S215000
Reexamination Certificate
active
06437016
ABSTRACT:
The invention relates to a radiation-curable compound and a composition comprising this compound.
During radiation curing processes the transformation of the fluid applied film to a solid crosslinked network can be considered to progress through three distinct stages being induction, polymerisation and attainment of maximum cure plateau. (Chemistry and Technology of UV and EB formulations, Volume IV, Oldring, 1991, pages 8-12).
Factors which improve or inhibit cure rate are, for example, the lamp system (UV-dose, intensity, wavelength, IR-content) and the chemical system (reactivity, absorption, coating weight, pigmentation, temperature, oxygen inhibition and substrate).
For commercial coating operations, it is necessary that the coating achieves a tackfree surface within seconds or less, because the interval between application of the coating and stacking or rewinding of the coated substrate is very short. Failure of the coating to achieve a non-tacky surface in this brief interval will result in the layers of coated substrate (in a stack or roll) sticking together (“blocking).
It is the object of the present invention to provide a coating composition having a high cure rate or rate of polymerisation and having the desired chemical and mechanical properies.
The radiation curable compound according to the invention is a mono or multi valent carboxylic ester of a compound containing a hydroxyalkylamidegroup and a hydroxygroup in which the carboxylic ester is derived from an &agr;,&bgr;-ethylenically unsaturated carboxylic acid.
A radiation curable composition comprising the compound according to the invention results in high maximum polymerization rates.
According to a preferred embodiment of the invention the compound is a compound according to formula (I):
where:
Y=hydrogen, an (C
1
-C
8
) alkyl group or
R
1
, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
, R
8
are, identical or different, hydrogen or a lineair, branched or cyclic (C
1
-C
8
) alkyl chain,
R
9
=hydrogen, (C
1
-C
5
)alkyl, —CH
2
OH or CH
2
COOX,
R
10
, R
11
=hydrogen, (C
1
-C
8
) alkyl, (C
6
-C
10
)aryl or COOX,
X=hydrogen or (C
1
-C
8
) alkyl,
m=1-10,
p=1-4 and
n=1-10
R
1
, R
2
or R
3
may form part of a cycloalkyl group.
Preferably n=1-4.
Because of the resulting excellent reactivity characteristics m is preferably 1-4.
Preferably, p is 1 or 2
Preferably, Y is hydrogen.
Preferably, R
1
, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
and R
8
are hydrogen or methyl.
R
9
is preferably hydrogen or (m)ethyl.
R
10
and R
11
are preferably hydrogen.
The compound can be obtained, for instance, by an esterification reaction between a hydroxy functional hydroxyalkylamide and an unsaturated carboxylic acid, at a temperature between, for example, 80° C. and 140° C.
Preferably, 1-1.5 mol of acid are used per mole of hydroxide.
Preferably, the reaction takes place in the presence of an organic solvent, such as, for example, xylene, toluene or tetrahydrofuran.
Preferably, the reaction takes place in the presence of a stabilizing compound which prevents polymerization of the unsaturated ester groups under the conditions used for effecting this reaction. The stabilising compound or a mixture of stabilising compounds is generally used in amounts between about 50 and about 2000 ppm and preferably between 75 and 1000 ppm. They can be used in aerobic or anaerobic conditions depending on the stabilising compound.
Suitable stabilizing compounds include, for example, hydroquinone, monomethylhydroquinone, anthraquinone, &bgr;-nitrostyrene, phenothiazine and 2,6-di-tert-butyl-4-methyl-phenol (BHT).
The esterification reaction may take place in the presence of a catalyst. Suitable catalysts include strong acids, for example, sulphur-containing organic acids like alkane sulphonic acids and methane sulphonic acid.
Suitable unsaturated carboxylic acids include, for example, (meth)acrylic acid and derivatives, crotonic acid, (semi-ester of) itaconic acid, maleic acid, citraconic acid, mesaconic acid and fumaric acid.
Preferably (meth)acrylic acid is applied.
The compound applied in the invention can also be obtained by the reaction between a hydroxy functional hydroxyalkylamide and an unsaturated carboxylic acid chloride, anhydride or ester.
Preferably, the reaction between the amide and the unsaturated chloride or anhydride takes place at temperatures between 0° C. and 30° C. in a solvent in the presence of a base. Suitable solvents include, for example, tetrahydrofuran, dichloromethane and diethylether. Suitable bases include, for example, pyridine and triethylamine.
Suitable chlorides, anhydrides or esters include the chlorides, anhydrides and esters of the in the foregoing mentioned carboxylic acids.
Preferably, the reaction between the amide and the unsaturated ester takes place at temperatures between 80° C. and 140° C. in the presence of a Lewis acid. Preferably, an excess of the unsaturated ester is applied. The ester functions both as solvent and as reactant. Suitable Lewis acids are, for example, tetra alkyl titanate and sulphuric acid.
According to a preferred embodiment of the invention the preparation of the compound according to the invention takes place by reaction between a hydroxy functional oxazoline and an unsaturated carboxylic acid.
Such a reaction can, for example, take place at a temperature between 50° C. and 140° C.
Suitable hydroxy functional oxazolines include, for instance, hydroxy functional (C
1
-C
20
) alkyloxazolines, for instance, &bgr;-hydroxy ethyl oxazoline and &OHgr;-hydroxy undecyloxazoline.
Suitable unsaturated carboxylic acids include, for example, (meth)acrylic acid and derivatives, crotonic acid, (semi-ester of) itaconic acid, maleic acid, citraconic acid, mesaconic acid and fumaric acid. Preferably, (meth)acrylic acid is used.
Preferably the hydroxy functional oxazolines are prepared from, for instance, a lactone and an ethanolamine or 2-propanolamine. Suitable lactones are for instance propiolactone, butyrolactone, valerolactone and caprolactone.
An advantage of the hydroxy functional compound according to the invention is that the hydroxy group gives the possibility for attaching this compounds to a polymer. A suitable method to obtain the attachment is to react first the hydroxyl functional compound with a diisocyanate and to react subsequent with an hydroxy functional polymer. Suitable diisocyanates are, for example, toluene diisocyanate, hexane diisocyanate, isophorone diisocyanate or 3,4-isocyanate methyl-1-methyl cyclohexyl isocyanate (IMCI). Suitable hydroxy functional polymers are, for example, hydroxy functional polyethylene, polypropylene, polyester, poly(meth)acrylate, polyamide, polyether, polyisobutylene, polyacrylonitrile, polyurethane and polylactone.
Additives can also be connected via the hydroxy functionality of the hydroxy functional compound according to the present invention.
Suitable additives include for example, adhesion promoters, disperging agents, photo initiators and synergists.
The compound according to the invention can be cured by means of a free-radical reaction. In these reactions the free radicals can be obtained by radiation initiation.
Radiation-curing preferably takes place by means of, for example, a photochemical process such as, for example, ultraviolet radiation (UV) or a radiation-chemical process such as electron beam (EB).
UV and EB radiation are explained in greater detail by for example Bett et al. in the article entitled “UV and EB curing” (Jocca 1990 (11), pages 446-453).
The amount of the compound according to the invention can range between 0,01% by weight and 100% by weight in a composition according to the invention.
Generally, the radiation curable composition according to the invention is substantially solvent free.
The composition according to the invention can be used, for example, in coating compositions, inks and adhesives.
If desired and depending on the application, the compound can be combined with oligomers or polymers which are based, for example, on (meth)acrylate units, maleate units, fumarat
Dias Aylvin J. A. A.
Jansen Johan F. G. A.
Tijssen Pascal M. H. P.
Berman Susan W.
DSM N.V.
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