Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
1999-07-29
2001-06-12
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, C560S205000, C560S215000
Reexamination Certificate
active
06245829
ABSTRACT:
The invention relates to a radiation-curable composition.
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 composition according to the invention comprises a mono or multi valent carboxylic ester of a &bgr;-hydroxyalkylamide group containing compound, in which the carboxylic ester is derived from an &agr;,&bgr;-ethylenically unsaturated carboxylic acid.
The composition according to the invention results in high maximum polymerization rates.
According to a preferred embodiment of the invention the compound is according to formula (I):
where:
A=hydrogen, or a monovalent or polyvalent organic group which is derived from a saturated or an unsaturated (C
1
-C
60
) alkyl group, or derived from an (C
6
-C
10
) aryl group,
Y=hydrogen, an (C
1
-C
8
) alkyl group or
R
1
, R
2
, R
3
, R
4
are, identical or different, hydrogen or a linear, branched or cyclic (C
1
-C
8
) alkyl chain,
R
5
=hydrogen, (C
1
-C
5
)alkyl, —CH
2
OH or CH
2
COOX,
R
6
, R
7
=hydrogen, (C
1
-C
8
) alkyl, (C
6
-C
10
)aryl or COOX
X=hydrogen or (C
1
-C
8
) alkyl and
p=1 or 2
R
1
, R
2
or R
3
may form part of a cycloalkyl group.
The organic groups in A may be substituted with, for example, ethers, esters, hydroxyl, amides, acids, amines or ketones.
Preferably, ester- or hydroxylgroups are applied as substitutents.
Preferably, A is a monovalent organic group which is derived from a saturated (C
1
-C
12
) alkyl group.
According to another preferred embodiment of the invention A is a polyvalent organic group derived from a saturated (C
2
-C
10
) alkyl group or a C
6
-aryl group.
Preferably, Y is hydrogen or methyl.
Preferably, R
1
, R
2
, R
3
and R
4
are hydrogen or methyl.
R
5
is preferably hydrogen or (m)ethyl.
R
6
and R
7
are preferably hydrogen.
The compound applied in the invention generally has a number-average molecular weight (Mn) of between 140 and 2500, and preferably of between 450 and 1000.
The compound can be obtained, for instance, by an esterification reaction between a &bgr;-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, citaconic acid, mesaconic acid and fumaric acid.
Suitable &bgr;-hydroxyalkylamides include, for example, N,N′-bis(di-&bgr;-hydroxyethyl)-1,6-hexanediamide, N-di-&bgr;-hydroxyethyl acetamide, N,N-bis(di-p-hydroxypropyl)-1,6-hexanediamide, N-di-&bgr;-hydroxypropyl acetamide, N-di-&bgr;-hydroxyethyl benzamide and N-di-&bgr;-hydroxypropyl benzamide. The compound applied in the invention can also be obtained by the reaction between of a &bgr;-hydroxyalkyl amide and an unsaturated carboxylic acid chloride, anhydride or ester.
The reaction between the amide and the unsaturated chloride or anhydride preferably takes place at temperature between 0° C. and 30° C. in a solvent in the presence of a base. Suitable solvents include, for example, tetrahydroferan, water, dichloromethane or diethylether. Suitable bases include, for example, pyridine or triethylamine.
Suitable chlorides, anhydrides or esters include the chlorides, anhydrides and esters of the in the foregoing mentioned carboxylic acid.
The reaction between the amide and the unsaturated ester, preferably, 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.
Another process for the preparation of the compound applied in the invention is the reaction between an oxazoline and an unsaturated carboxylic acid.
Such a reaction can, for example, take place between 50° C. and 140° C.
Suitable oxazolines include, for instance, oxazoline and (C
1
-C
20
) alkyloxazolines, for instance, ethyl oxazoline and undecyloxazoline.
Suitable unsaturated carboxylic acids include, for example, (meth)acrylic acid and derivatives, crotonic acid, (semi-ester of) itaconic acid, maleic acid, citaconic acid, mesaconic acid and fumaric acid. Preferably, methacrylic acid and acrylic acid are used.
The compound applied in 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 formule (I) can range between 0.01% by weight and 100% by weight in the 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, fumarate units, itaconate units, vinylester units and/or vinylether units.
Due to the relatively high cure speeds the present compounds can also be applied as additives for enhancing the cure speed of a formulation. In general such additives are used in amounts ranging between 0.01% and 25% by weight and preferably in amounts between 0.5% and 10% by weight relatively to the total amount of all ingredients.
After curing the coatings according to the invention have many desired properties such as for example good chemical properties (resistance to solvents, acids, alkalis and mois
Dias Aylvin J. A. A.
Houweling Marten
Jansen Johan F. G. A.
Meij Theodoor H.
Van Benthem Rudolfus A. T. M.
Berman Susan W.
DSM NV
Pillsbury & Winthrop LLP
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