Imaged members and method of preparation thereof

Details Imaged members and method of preparation thereof Imaged members and method of preparation thereof

2001-08-17

2003-05-13

Chu, John S. (Department: 1752)

Radiation imagery chemistry: process, composition, or product th

Imaged product

Including resin or synthetic polymer

C430S175000, C430S176000, C430S281100, C430S288100, C430S313000, C430S314000, C430S318000, C430S323000, C430S324000

Reexamination Certificate

active

06562527

ABSTRACT:

BACKGROUND OF INVENTION
1. Field of the Invention
This invention relates to methods of preparing relief-treated imaged members and members prepared thereby, using negative working photosensitive compositions.
2. Background Information
Imagable members, such as lithographic printing form precursors, electronic part precursors and mask precursors, conventionally comprise a substrate onto which is coated a film-forming radiation-sensitive composition. After image-wise exposure of the precursor to radiation of suitable wavelength, and development of the imaged precursor, an imaged article is produced.
Negative working imagable members have a radiation sensitive coating, which, when image-wise exposed to radiation of a suitable wavelength, hardens in the exposed areas. On development, the non-exposed areas of the coated compositions are removed, leaving behind the desired image.
The coatings are normally applied as solutions in organic solvents, which are removed by evaporation. Conventionally, ultra-violet or visible radiation has been employed to image compositions sensitive to those wavelengths.
Radiation-sensitive coatings for use in lithographic printing forms desirably have certain physical and chemical properties. In particular in negative working lithographic printing forms the radiation-sensitive coatings employed must be relatively less soluble in a desired developer liquid after exposure with suitable radiation, compared with the pre-exposure solubility of the coating. Furthermore the coatings should desirably have excellent mechanical attrition.
Some negative-working radiation-sensitive compositions used in coatings on lithographic printing forms employ polymers having pendent acetal moieties. Such polymers have been shown to exhibit useful properties when used in conjunction with photosensitive components. The resultant photosensitive compositions, when coated on lithographic printing form precursors, exhibit good developability and mechanical attrition resistance.
EP 752 430 discloses binders for use in lithographic printing plates and precursors. These binders comprise alkyl acetal moieties and carboxylic acid-bearing acetal moieties, and are described as having desirable characteristics for use in coatings on lithographic printing forms.
U.S. Pat. No. 5,700,619 discloses photosensitive compositions comprising the binders of EP 752 430 and a diazonium polycondensation product or free radial polymerizable system, or both. These photosensitive compositions have good development characteristics when used in a coating on a lithographic printing plate precursor.
U.S. Pat. No. 5,925,491 discloses photosensitive compositions comprising a radical polymerizable system and a binder having acetal moieties and amido moieties. The polymeric binders disclosed therein exhibit improved ink acceptance, developability and image resolution when used in coatings on lithographic printing forms.
EP 996 037 discloses binders comprising polyvinyl acetal moieties and imido-substituted acetal moieties, and their use in photosensitive compositions coated onto lithographic printing form precursors. These binders exhibit good adhesion to printing form substrates and good developability and ink acceptance.
U.S. Pat. No. 5,849,842 discloses binders comprising alkyl acetal moieties and sulfonamido substituted acetal moieties, and their use in photosensitive composition used as coatings on lithographic printing form precursors. These binders exhibit good ink acceptance, developability and mechanical attrition resistance, and improve the number of prints produced from the printing form vis-à-vis compositions described in the state of the art.
It has now been found that binders containing pendent acetal and substituted acetal moieties currently used in coatings on lithographic printing forms also exhibit excellent resistance to relief-treatment agents commonly used to relief-treat imaged members such as printed circuit boards (PCBs). Thus binders containing pendent acetal and substituted acetal moieties can be used in photosensitive compositions used as coatings on imagable members which are image-wise exposed and relief-treated, and the coatings exhibit improved relief-treatment agents resistance vis-à-vis prior art relief-treatment agent resistant coatings.
It has also now been found that coatings employing binders containing pendent acetal and substituted acetal moieties may be coated at much lower coating weights compared to prior art coatings used in etch resist applications. Prior art coatings such as the IMAGELINE XV750 coating produced by Coates Circuit Products, the PHOTOPOSIT SN35 Coatings produced by Shirley and the MICROTRACE LIQUID RESIST produced by MacDermid are all coated at weights of around 10 gm
−2
. Coatings of this invention employing binders containing pendent acetal and substituted acetal moieties may be coated at lower weights and still retain excellent relief-treatment agent resistance, after image-wise development of the imagable article. In addition, coatings of this invention also exhibit reduced development times, reduced exposure times, and the need to rub off the unexposed coating after imaging and development is mitigated.
SUMMARY OF THE INVENTION
According to the present invention, a method of manufacturing a selectively relief-treated imaged member comprises:
(a) providing a precursor of the imaged member, the precursor comprising a surface having an image-forming layer comprising a photosensitive resist composition comprising:
(i) a polymerizable material, and
(ii) a binder comprising the units A, B, C and D, wherein A is present in an amount of 5 to 80 mole % of the binder and is of the formula:
 B is present in an amount of 10 to 60 mole % of binder and is of the formula
 C is present in an amount of 0.1 to 30 mole % of the binder and is of the formula:
 D is present in an amount of 1 to 70 mole % of the binder and is selected from the group consisting of:
 wherein
R
1
represents a hydrogen atom, alkyl group, aryl group or alkenyl group,
R
2
represents a hydrogen atom or alkyl group,
R
3
and R
4
are independently selected from a hydrogen atom or an alkyl group,
L represents either the group —NH CO—R
12
—CO—NH—R
13
, wherein R
12
is selected from a hydrogen atom, an alkyl group, an alkenyl group, or an acryl group, optionally substituted by a carboxyl group, and R
13
is a C
1
-C
6
hydrocarbon group, optionally substituted by one or more hydroxyl, C
1
-C
3
ether or amino, mono C
1
-C
3
alkyl amino, di-C
1
-C
3
alkylamino or carboxyl groups, or an aryl group having at least one carboxyl or sulfonic acid group,
R
5
and R
6
are independently selected from a hydrogen atom and an alkyl group and n is an integer from 1 to 3,
R
7
is selected from an alkyl group, aryl group or alkenyl group,
R
8
and R
9
are independently selected from a hydrogen atom or an alkyl group, or R
8
and R
9
, together with the two carbon atoms they are attached to, represent a 5 or 6 membered carbocyclic ring,
Y is selected from the group consisting of OC—Z—COOR
10
and SO
2
R
11
,
wherein R
10
is selected from a hydrogen atom or an alkyl group,
R
11
is selected from an alkyl group, an alkenyl group or an aryl group,
and Z is a saturated or unsaturated chain or ring-shaped spacer group;
(b) delivering radiation image-wise to the precursor;
(c) developing the precursor in a developer to selectively remove the image-forming layer in regions in which the radiation was not delivered image-wise in step (b); and
(d) contacting the image-wise exposed member with a relief-treatment material, to selectively relief-treat regions of the surface of the member in which the image-forming layer was removed on development in step (c).
DETAILED DESCRIPTION OF THE INVENTION
As used herein, “relief-treatment” refers to any treatment which removes material from or deposits material on a developed precursor in the regions where the image-forming layer has been removed on development. The effect of such a relief-treatment is to form depressions or projections from the pl

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