Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
1999-11-17
2002-11-26
Reddick, Judy M. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S015000, C522S016000, C522S017000, C522S018000, C522S020000, C522S021000, C522S025000, C522S026000, C522S027000, C522S028000, C522S029000, C522S075000, C522S077000, C522S079000, C522S081000, C522S083000, C522S090000, C522S092000, C522S096000, C522S100000, C522S103000, C522S172000, C524S701000, C524S718000
Reexamination Certificate
active
06486225
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a photocurable composition, more specifically, the present invention relates to a photocurable composition capable of completely curing through the interior of the composition even when the composition contains a pigment or color dye having high hiding power, has a large thickness or contains a material having poor light transmittance.
BACKGROUND OF THE INVENTION
In recent years, from the standpoint of quick curability, cold curability, employing a solventless system and energy savings, radial photopolymerization and cationic photopolymerization are being noticed and are being used in diversified uses such as printed board fabrication, resist or photomask formation, wood painting, optical fiber coating, hard coating on plastics or can coating.
At present, photocuring is dominated by ultraviolet curing where a polymerizable monomer is abruptly cured by irradiation with an ultraviolet ray of from 200 to 400 nm. However, an ultraviolet ray of 400 nm or less is poorly transmitted into a material and has a problem in that in the case of a composition containing a color pigment or color dye in a high concentration, the surface thereof is cured but the interior is not satisfactorily cured. Even a transparent system free of pigment, color dye or the like has a similar problem in that when the curing system has a large thickness or contains a material having poor ultraviolet transmittance, the interior of the curing system is not satisfactorily cured.
In order to solve this problem, JP-B-63-40799 (the term “JP-B” as used herein means an “examined Japanese patent publication”) discloses an acylphosphine oxide-type initiator and JP-A-6-298818 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) discloses a bisacylphosphine oxide-type initiator. These photopolymerization initiators can be decomposed not only by an ultraviolet ray of 400 nm or less but also by a visible light of from 400 to 450 nm to generate radicals, therefore, a relatively large thickness can be obtained after curing even if the composition contains a material having poor ultraviolet transmittance, however, the thickness is still not sufficiently large. Furthermore, the initiators are disadvantageous in that depending on the hue of the color pigment present in the composition, the thickness after the curing greatly varies.
JP-A-6-75374 and JP-A-10-81838 disclose a photocurable composition containing a color pigment, where a radical photopolymerization initiator comprising a near infrared absorbing cationic dye or visible light absorbing cationic dye and an organic borate-type sensitizer are added to increase internal curability. By using this composition, a sufficiently large thickness may be cured but the greater part of radicals generated from the organic borate-type sensitizer are consumed in a decolorization reaction of the cationic dye and the absolute amount of radicals participating in the polymerization is small. As result, the degree of curing of the cured product is disadvantageously deficient.
JP-A-10-195119 discloses a photopolymerizable composition comprising (a) a compound having a urethane skeleton within the molecule, which is an addition polymerizable compound having at least one ethylenic double bond, (b1) a dye cation and (b2) a borate anion represented by a specific formula. JP-A-3-111402 discloses a near infrared photopolymerization initiator comprising a dye cation and a borate anion and JP-A-5-194619 discloses a near infrared photopolymerization initiator comprising a dye cation compound and a borate anion compound, in which examples of the urethane acrylate containing such a near infrared photopolymerization initiator (a compound having a double bond and a urethane bond within the molecule) are described but none of them provides satisfactory cured thickness and degree of curing.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a photocurable composition suitable for use in the field of coating material, adhesive, pressure sensitive adhesive, ink, a hologram material and the like, the photocurable composition being sufficiently curable through the interior of the composition even in a curing system containing a coloring material having hiding power, such as a color pigment or a color dye, or containing a material having a low ultraviolet transmittance, which system is heretofore difficult to photocure.
In order to solve this problem, the present inventors have made extensive investigations on a photocurable composition using a combination of a cationic dye having an absorption maximum wavelength in the wavelength region of from 400 to 1,200 nm and a quaternary borate-type compound as a sensitizer thereof and have found that when a specific urethane (meth)acrylate oligomer is used as the radical polymerizing component, the photocurable composition obtained can provide a sufficiently large cured thickness and a high curing degree even when the composition contains a color pigment or color dye having hiding power. The present invention has been accomplished based on this finding.
More specifically, the present invention provides:
1) a photocurable composition comprising (A) 100 parts by weight of a compound having an ethylenically unsaturated group, (B) from 0.001 to 5 parts by weight of a cationic dye having an absorption maximum wavelength in the wavelength region of from 400 to 1,200 nm, represented by formula (1):
D
+
·A
1
−
(1)
wherein D
+
represents a cation having an absorption maximum wavelength in the wavelength region of from 400 to 1,200 nm, and A
1
−
represents an anion and (C) from 0.005 to 10 parts by weight of a quaternary borate-type compound represented by formula (2):
wherein R
1
, R
2
, R
3
and R
4
each independently represents an alkyl group, an aryl group, an aralkyl group, an alkenyl group, an alkynyl group, a silyl group, a heterocyclic group or a halogen atom, and Z
+
represents a cation, wherein from 5 to 95 wt % of (A) the compound having an ethylenically unsaturated group is a urethane (meth)acrylate oligomer obtained by the reaction of a polyisocyanate having three or more isocyanate groups within one molecule with a hydroxyl group-containing (meth)acrylic acid ester;
2) the photocurable composition as described in 1) above, wherein from 3 to 40 wt % of the compound having an ethylenically unsaturated group is occupied by an N-vinylamide-type compound;
3) the photocurable composition as described in 2) above, wherein the N-vinylamide-type compound is one or more compound selected from the group consisting of N-vinylformamide, N-vinylacetamide and N-methyl-N-vinylacetamide;
4) the photocurable composition as described in 1) to 3) above, wherein the cation (D
+
) having an absorption in the region of from 400 to 1,200 nm is one or more compound selected from the group consisting of polymethine-, xanthene-, acridine-, azine-, oxazine-, thiazine-, diarylmethane- and triarylmethane-type compounds;
5) the photocurable composition as described in 4) above, wherein the polymethine compound is a compound represented by formula (3):
wherein R
5
, R
6
, R
7
, R
8
and R
9
each independently represents a hydrogen atom, an alkyl group, an aryl group or a halogen atom;
6) the photocurable composition as described in 1) to 5) above, which further contains from 0.1 to 10 parts by weight of an ultraviolet radical photopolymerization initiator capable of generating a radical by absorbing light at a wavelength of from 200 to 400 nm;
7) the photocurable composition as described in 1) to 6) above, wherein the polyisocyanate having three or more isocyanate groups within one molecule is one or more compound selected from the group consisting of an isocyanurate form of diisocyanate, a biuret form of a diisocyanate and an adduct form of a diisocyanate with a polyol;
8) the photocurable composition as described in 7) above, wherein the diisocyanate is one or more compound selected from the group consisting of aliphatic diisocy
Kamata Hirotoshi
Koshikawa Toshio
Ooga Kazuhiko
Watanabe Takeo
Reddick Judy M.
Showa Denko Kabushiki Kaisha
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