1. An initiator system comprising:
(a) at least one substance capable of absorbing IR radiation,
(b) at least one compound capable of forming free radicals, and
(c) at least one 1,4-dihydropyridine derivative of the formula (I)
wherein
R1 is selected from a hydrogen atom, \u2014C(O)OR7, an optionally substituted alkyl group, an optionally substituted aryl group and an optionally substituted aralkyl group,
R2 and R3 are independently selected from optionally substituted alkyl groups, optionally substituted aryl groups. CN and a hydrogen atom, R4 and R5 are independently selected from \u2014C(O)OR7, \u2014C(O)R7, \u2014C(O)NR8R9 and CN,
or R2 and R4 together form an optionally substituted phenyl ring or a 5- to 7-membered carbocyclic or heterocyclic ring, wherein the unit
is present in the carbocyclic or heterocyclic ring adjacent to position 5 of the dihydropyridine ring and wherein the carbocyclic or heterocyclic ring optionally comprises additional substituents,
or both R2 and R4 as well as R3 and R5 form either optionally substituted phenyl rings or 5- to 7-membered carbocyclic or heterocyclic rings, wherein the unit
is present in the carbocyclic or heterocyclic rings adjacent to positions 3 and 5 of the dihydropyridine ring and wherein the carbocyclic or heterocyclic rings optionally comprise additional substituents,
or one of the pairs R2R4 and R3R5 forms a 5- to 7-membered carbocyclic or heterocyclic ring, wherein the unit
is present in the carbocyclic or heterocyclic ring adjacent to position 5 or 3 of the dihydropyridine ring and wherein the carbocyclic or heterocyclic ring optionally comprises additional substituents and the other pair forms an optionally substituted phenyl ring,
or R2 and R1 or R3 and R1 form a 5- to 7-membered heterocyclic ring which can optionally comprise one or more substituents and which, in addition to the nitrogen atom it shares with the 1,4-dihydropyridine ring, optionally comprises additional nitrogen atoms, \u2014NR13 groups, \u2014S\u2014 or \u2014O\u2014,
R6 is selected from an alkyl group optionally substituted with a halogen atom or a \u2014C(O) group, an optionally substituted aryl group, an optionally substituted aralkyl group, an optionally substituted heterocyclic group and the group
Y is an alkylene group or an arylene group,
R7 is a hydrogen atom, aryl group, aralkyl group or alkyl group, wherein the alkyl group and the alkyl unit of the aralkyl group optionally comprise one or more C\u2014C double andor C\u2014C triple bonds,
and R8 and R9 are independently selected from a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aryl group and an optionally substituted aralkyl group.
2. The initiator system according to claim 1, wherein component (a) is a cyanine dye.
3. The initiator system according to claim 1 wherein the at least one substance capable of absorbing IR radiation is an IR dye of the formula II
wherein
each X independently represents S, O, NR or C(alkyl)2;
each R\u2032 independently represents an alkyl group, an alkylsulfonate group or an alkylammonium group;
R\u2033 represents a halogen atom, SR, OR or NR2;
each R\u2032\u2033 independently represents a hydrogen atom, an alkyl group, \u2014COOR, \u2014OR, \u2014SR, \u2014NR2 or a halogen atom; R\u2032\u2033 can also be a benzofused ring;
A\u2212 represents an anion,
— represents an optionally present carbocyclic five- or six-membered ring;
R represents a hydrogen atom, an alkyl or aryl group;
each n can independently be 0, 1, 2 or 3.
4. The initiator system according to claim 1 wherein the IR absorber is
2-2-2-thiophenyl-3-2-(1,3-dihydro- 1,3,3-trimethyl-2H-indole-2-ylidene)-ethylidene-1-cyclohexene-1-yl-ethenyl-1,3,3-trimethyl-3H-indoliumchloride,
2-2-2-chloro-3-2-(1,3-dihydro-1,3,3-trimethyl-2H-indole-2-ylidene)-ethylidene-1-cyclohexene-1-yl-ethenyl-1,3,3-trimethyl-3H-indolium-tosylate or
2-2-2-chloro-3-2-ethyl-3H-benz-thiazole-2-ylidene)-ethylidene-1-cyclohexene-1-yl-ethenyl-3-ethyl-benzthiazolium-tosylate.
5. The initiator system according to claim 1 wherein component (b) is a polyhalogenalkyl-substituted compound.
6. The initiator system according to claim 1 wherein component (b) is
2-phenyl-4,6-bis-(trichloromethyl)-s-triazine,
2-(4-methoxyphenyl)-4,6-bis(chloromethyl)-s-triazine,
tribromomethyiphenylsulfone or
2,4,6-tri-(trichloromethyl)-s-triazine.
7. The initiator system according to claim 1 wherein a 1,4-dihydropyridine derivative of formula (I) is used wherein R1 is a hydrogen atom.
8. The initiator system according to claim 1 wherein a derivative with R2\u2550R3 and R4\u2550R5 is used.
9. The initiator system according to claim 1 wherein R2 and R3 are independently selected from optionally substituted alkyl groups, optionally substituted aryl groups, CN and a hydrogen atom, and R4 and R5 are independently selected from \u2014C(O)OR7, \u2014C(O)R7, \u2014C(O)NR8R9 and CN, arid R7, R8 and R9 are as defined in claim 1.
10. The initiator system according to claim 1 wherein the 1,4-dihydropyridine derivative is a compound of formula (Ia)
wherein R1 and R6 are as defined above,
the groups R8a to R8d and R9a to R9d are independently selected from a hydrogen atom, alkyl groups and aryl groups, wherein two groups R8 andor two groups R9 of adjacent ring carbon atoms can also form a saturated or unsaturated carbocyclic or heterocyclic ring or fused aromatic ring together,
each Z is independently selected from CR132, O, S and NR13 and
each R13 independently represents a hydrogen atom, alkyl, aryl or aralkyl group,
of formula (Ib)
wherein R1 and R6 are as defined above, and
R10a to R10d and R11a to R11d are independently selected from a hydrogen atom, alkyl groups, aryJ groups, aralkyl groups, halogen atoms, CN, NR132, C(O)OR13 and OR13, wherein each R13 is independently selected from a hydrogen atom, aryl, alkyl or aralkyl, wherein two groups R11 andor two groups R10 of adjacent ring carbon atoms can also form an unsaturated carbocyclic or heterocyclic ring or fused aromatic ring together,
of formula (Ic)
wherein R1, R3, R5 and R6 are as defined above and the groups R9a to R9f are defined as are groups R9a to R9d of formula (Ia),
of formula (Id)
wherein each R1, R2, R3, R4 and R5 independently is as defined above and Y is selected from alkylene and arylene,
of formula (le)
wherein R2, R4, R5 and R6 are as defined above and groups R9a to R9f are as defined above for formula (Ic),
of formula (If)
wherein R2, R4, R5 and R6 are as defined above and groups R9a to R9h are defined as are groups R9a to R9d of formula (Ia) above
or of formula (Ig)
wherein R2, R4, R5 and R6 are as defined above and the groups R11a to R11d are independently selected from a hydrogen atom, alkyl groups, aryl groups, aralkyl groups, halogen atoms, CN, NR132, C(O)OR13 and OR13, wherein two groups R11 of adjacent ring carbon atoms can also form an unsaturated carbocyclic or heterocyclic ring or fused aromatic ring together and each R13 is independently selected from hydrogen, alkyl, aryl and aralkyl.
11. An IR-sensitive composition comprising:
(i) a free-radical polymerizabie system comprising unsaturated monomers or prepolymers that are free-radical polymerizable and an initiator system according to claim 1 and
(ii) a polymeric binder.
12. The composition according to claim 11, additionally comprising at least one additive selected from contrast dyes, exposure indicators, plasticizers, surfactant, leuco dyes and mercapto compounds.
13. The composition according to claim 11 wherein the polymeric binder has an acid number of >40 mg KOHg.
14. An imageable element comprising a substrate and a coating with the composition of claim 11 and optionally an oxygen-impermeable overcoat.
15. The imageable element according to claim 14 wherein the substrate is an optionally pretreated aluminum plate or foil.
16. The imageable element according to claim 14 that is a printing plate precursor.
17. A process for the production of an imageable element comprising:
(a) providing an optionally pretreated substrate,
(b) providing the IR-sensitive composition of claim 11,
(c) applying the IR-sensitive composition onto the substrate and optionally
(d) applying an oxygen-impermeable overcoat.
18. A process for imaging an imageable element comprising:
(a) providing the imageable element of claim 14,
(b) image-wise exposure of the imageable element to radiation of a wavelength selected from the range of 750 to 1,300 nm, and
(c) removing the unexposed areas of the exposed element by means of an aqueous alkaline developer.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A roller bearing cage in which a cylindrical cage is split along any diametral plane thereof into a pair of two semicircular cage halves that are arranged in opposition to each other with their mating ends coming into abutment against each other: comprising that the semicircular cage halves are each composed of semicircular rims arranged in a way spaced axially apart from each other and extended circumferentially in parallel with each other, and cage bars positioned between the semicircular rims at regular intervals around curved surfaces of the rims and made integrally with the rims to form a pocket between any two adjacent cage bars, in which a roller is accommodated for rotation; the semicircular cage halves are chamfered off at any outer peripheral areas nearby the mating ends thereby to form chamfered even areas; and the chamfering operation is done preparatory to cutting off the cylindrical cage into two semicircular cage halves.
2. A roller bearing cage constructed as defined in claim 1, wherein the chamfered even areas on the outer peripheral areas are roughly normal to the mating ends of the semicircular cage halves and also lying on planes that extend in parallel with each other in diametral opposition.
3. A roller bearing cage constructed as defined in claim 1, wherein the cage bar having the mating end thereon is roughly equal in circumferential width with other cage bar.
4. A roller bearing cage constructed as defined in claim 1, wherein the cage bars are arranged with their outside surfaces being in flush relation with the outside peripheries of the rims.
5. A roller bearing cage constructed as defined in claim 1, wherein the cage bar has an inside surface that is sunk at an axial middle area thereof to form a recess extending in depth radially outwardly beyond a diameter across pitch circle on the rollers and in axial length shorter than the pocket, so that the cage bar is made slender at the middle area thereof on account of the recess, with leaving axially opposing ends thereof thick, and circumferentially opposing cheeks of the thick ends provide guide surfaces on which the roller rolls.
6. A roller bearing cage constructed as defined in claim 5, wherein on the thick ends of the cage bar there are provided outside retainer lugs that jut into the pocket to keep the roller against outward escape out of the associated pocket and inside retainer lugs that also jut into the pocket to keep the roller against inward escape out of the associated pocket.
7. A roller bearing cage constructed as defined in claim 5, wherein an annular corner where the inside peripheral surface and any one end of the axially opposing end surfaces of the semicircular rims merge with each other is chamfered off into a depth reaching one-third an axial thickness of the associated rim to form a slant annular surface, which slopes to a plane normal to an axial direction of the rim, with an angle less than 45 deg.
8. A roller bearing cage constructed as defined in claim 1, wherein the edge where the outer periphery of the semicircular rim and the cage bar merges with the associated mating end is chamfered off.
9. A roller bearing cage set constructed as defined in claim 1, wherein a corner where the axial end surface of the semicircular rim merges with the outside periphery of the semicircular rim is slightly rounded.
10. A roller bearing cage wherein a cylindrical cage is composed of a pair of annular rims arranged in a way spaced axially apart from each other and extended circumferentially in parallel with each other, and cage bars positioned between the annular rims at regular intervals around curved surfaces of the rims and made integrally with the rims to form a pocket between any two adjacent cage bars, in which a roller is accommodated for rotation; the cage bars are arranged with their outside surfaces being in flush relation with the outside peripheries of the rims; the cage bar has an inside surface that is sunk at an axial middle area thereof to form a recess extending in depth radially outwardly beyond a diameter across pitch circle on the rollers and in axial length shorter than the pocket, so that the cage bar is made slender at the middle area thereof on account of the recess, with leaving axially opposing ends thereof thick, and circumferentially opposing cheeks of the thick ends provide guide surfaces on which the roller rolls, and further wherein on the thick ends of the cage bar there are provided outside retainer lugs that jut into the pocket to keep the roller against outward escape out of the associated pocket and inside retainer lugs that also jut into the pocket to keep the roller against inward escape out of the associated pocket.
11. A roller bearing cage constructed as defined in claim 10, wherein an annular corner where the inside peripheral surface and any one end of the axially opposing end surfaces of the annular rims merge with each other is chamfered off into a depth reaching one-third an axial thickness of the associated rim to form a slant annular surface, which slopes to a plane normal to an axial direction of the rim, with an angle less than 45 deg.
12. A roller bearing cage constructed as defined in claim 10, wherein a corner where the axial end surface of the annular rim merges with the outside periphery of the annular rim is slightly rounded.
13. A roller bearing cage constructed as defined in claim 5, wherein the slender area of the cage bar is defined in a manner having an inside surface of an axial length extending over a range of from 50% to 80% of an axial length of the pocket.
14. A roller bearing cage constructed as defined in claim 5, wherein a slant surface connecting the slender area and any one of the thick ends is set to slope to a plane normal to the slender area, with an angle less than 45 deg.
15. A roller bearing cage constructed as defined in claim 6, wherein the outside retainer lugs formed on the thick ends of the cage bar are designed in such a manner that their radially outside tops are held in flush relation with the outer periphery of the cage bar.
16. A roller bearing cage constructed as defined in claim 1, wherein an axially middle area of the cage bar is reduced sidewise on circumferentially opposing cheeks thereof to enlarge widthwise the pocket.
17. A roller bearing cage constructed as defined in claim 1, wherein the cage is made in an outside guide construction in which the outside periphery thereof is guided along a bore surface in a rod end of a connecting rod.