CA1062073A - Light-sensitive composition of diazo compound and isocyanate graft polymer - Google Patents

Abstract

Abstract of the Disclosure A light-sensitive coating composition and a light-sensitive photomechanical structure, such as a printing plate or a photoresist is produced by coating a suitable planar substrate with a condensation product of an organic i-socyanate and a polymeric resin having functional groups reactive with the isocyanate, such as phenol-formaldehyde resin, and a light-sensitive diazo compound, such as the esters and amides of quinone and naphthoquinone diazides, the coating being softenable by exposure to light and sub-sequent treatment with a conventional liquid printing plate developer, such as an aqueous alkaline solution and/or an organic solvent.

Description

106~ 73 J LIGHT-SENSITIVE COMPOSITION OF DIAZO COMPOUND

AND ISOCYANATE GRAFT POLYMER
..... _ , Back~round of the Inventlon ;
The present inventlon relates to llght-sensitlve compounds and compositlons suitable for use in the graphlc arts. More par-tlcularly, the present inventlon relates to the use of the conden-sation products of organlc lsocyanates and polymeric materials, carrylng functlonal groups whlch are capable of reactlng wlth the organlc lsocyanates, ln the manufacture of printing plates and photoresists.
In the manufacture of posltlve-worklng prlntlng plate s and photoreslsts, derlvatlves of naphthoqulnone dlazldes, as disclos-ed ln U. S. Patents Nos. 3,046,110-119, 3,046,121-124, 3,106,465, 3,148,983, 3,180,733, and 3,188,210, are wldely used as llght-sensltlve materlals. These naphthoqulnone dlazldes are generally soluble ln certaln organlc solvents but are not ' soluble ln water, weak aclds and weak alkalles. Coatlng solu-tions can be prepared utllizing one or more of these naphthoqui-none dlazide llght-sensltlve composltlons ln organlc solvents and `--the solution then coated on a suitable substrate such as alumi-num, zinc, copper, plastics, paper, etc. The cholce of the substrate depends on the intended use of the structure. When ^
a substrate, coated with one of these light-sensitive composl-tions, is exposed to light through an imaged transparency, naphthoqulnone diazides, in the exposed areas, are believed to be decomposed to the indene carboxyllc aclds, which are soluble in a weak alkaline solution. Therefore, through the iB -1-~ AZ 745 106~073 action o~ the light, a solubility differential between the exposed and unexposed areas results. The image can then be developod out by treatment with a prope~ weak alkaline deve-loper solution and removal of the solubilized non-image areas.
The compounas described in the above-mentioned U. S. patents, many of which have been reported elsewhere, are low molecular weight esters and acid amides of quinone ~r naphthoquinone diazide. ,If such a compound is used in-dividually, for instance, in the manufacture of lithographic printing plates, it is deposited in crystalline form, which results in lowering the mechanical strength of the image obtained and making long pres~ runs difficult to attain.
Accordingly; a 5uitable polymeric resinous material is usu-ally used as a carrier for the light-sensitive compound to prevent it from crystallizing and to compensate for any weak-ening of the mechanical strength. Suitable polymeric ma-terials, which are employed for thi~ purpose, are alkali-~s~luble resins such as shellac, styrene-maleic anhydride copolymers, hydrophobic thermoplastic polyurethanes (U. S.
Patent No. 3,660,097) and, especiaily, low molecular weight ~ondensation products of phenol and formaldehyde, the so-called 'novolaks' (U S. Patent Nos. 3,148,983 and 3,188,210 and many others). However, when an alkali-soluble resin, such as the novolak available under the trademark of "Alno-vol PN 430", manufactured by Chemische Werk Albert, Wiesbaden-Biebrich, Germany, is used as recommended in the prior art, the unexposed areas of the sensitized coating do not possess -the requisite adhesion to the substrate and tend to separate therefrom. Such a tendency becomes particularly manife~t 106~073 during the development operation, i.e., those instances wherein the plate is subjected to continued and prolonged immersion in the developer solution. Therefore, the image contrast and edge sharpness as well as press performance deteriorate. In cases where good plate performance is re-quired, it is necessary to heat-treat the developed plates at an elevated temperature so that a more durable printing surface can be obtained. However, such treatment usually yields a surface with many pinholes and spots. Therefore, the commercial value of such a system is greatly reauced.
Conversely, when a hydrophobic polymeric material, such as the Estane~ thermoplastic polyurethanes sold by B. F.
Goodrich Company, is used as a carrier (U. S Patent No.
3,660,097~ or the light-sensitive compounds, considerable difficulty is encountered in removing the exposed area of the sensitized coating, since the aqueous developer so-lution is uniformly repelled from the surface. Therefore, a preponderance of light-sensitive compounds would have to be incorporated in the coating compositions so that the sensitized layer will be more permeable to the alkaline developer. Use of a high percentage of sensitizer, in this manner, yields coatings which require long exposure time and are slow to develop, besides being unduly costly. In many instances, it is necessary to add a small amount of organic solvents to the alkaline developer to speed up the removal of the hydrophobic polymeric layer. In such cases, the resistance of the image areas to the alkaline developer is greatly reduced.
B

l~Z~73 AZ 745 In accordance with the present invention, these drawbacks of the prior art can be overcome, or at least considerably minimized, by using polymeric materials which have been especially chemically modified for photographic reproduction applications.
One object of this invention i9 to provide such novel chemically-modified polymeric materials.
An additional object is to provide light-sensitive , compositions containing isocyanate-modified polymeric materials.
A further object is to provide light-sensitive compositions, based on isocyanate-modified polymeric materi-al~, and systems using these compo~itions to prepare litho-graphic printing plates, photoresists, and similar photo-mschanical images.
A still further object is to provide light-sensi-tive alements with improved image adhesion and developer re-sistance.
- Additional objects will,be apparent to those skilled in the art rrom the following detailed description of the present invention.
Detailed Description of the Invention In accordance with the present invention, there is provided a novel class of isocyanate-modified polymeric materials. The polymeric materials of this invention can ,, be obtained by conventional methods of reacting organic isocyanates with suitable organic solvent-soluble polymers, bearing functional groups which are reactive ~oward the _4_ ... . . . .

106~Z073 Organic isocyanates. The organic solvents chosen as the reaction medium are inert toward and non-reactive with iso-cyanates, yet wiil readily dissolve the polymers to he modi-fied. The polymeric materials obtained after such isocyanate modification, can be used, alone or in conjunction with other suitable polymeric materials, as carriers for light-sensi- -~
tive quinone diazide compounds in a light-sensitive compo- -~
sition.
A detailed listing of the different functional groups which are reactive with organic isocyanates can be found in Chemical Reviews, vol. 57, pp. 47-76, 1957. Among the reactive groups mentioned, hydroxy, amino and thio groups are especially valuable, although other groups are not to be excluded. The~e functional groups may be substituted direct-ly on the main polymer chain as well as on side chains.
The organic solvent-soluble polymeric material, carrying reactive groups, may be a natural polymer, a chemically-modified natural polymer, a synthetic polycon-densation polymer or a polyaddition polymer, etc., provided it is organic solvent-soluble. The following polymers are also found to be useful: hydroxy-rontaining acrylic resins, such as copolymers containing hydroxyethyl methacrylate;
polyesters of polyhydroxy intermediates, such as trimethylol propane, glycerol and sorbitol, which have hydroxyl groups remaining after incorporation in thé polymer chain; amino-aryl- and hydroxyarylaldehyde resins, such as aniline-for-maldehyde resin and phenol-formaldéhyde resin; and the like.

Any of a variety of organic isocyanates can be - employed in preparing the present isocyanate-modified poly-mers, including aromatic, aliphatic and cycloaliphatic mono-isocyanates, diisocyanates and polyisocyanates and combina-tions thereof. Representative specific compounds, include;
ethyl i90cyanate, 2-chloroethyl isocyanate, butyl isocyanate, t-butyl isocyanate, hexyl isocyanate, octyl isocyanate, dodecyl isocyanate, phenyl isocyanate, o , m-, p-chloro-phenyl isocyanates, o-, m-, p-methoxyphenyl-isocyanates, o-, m-, p-nitrophenyl isocyanates, o-, m-, p-tolyl isocyan- ;
ates, cyclohexyl isocyanate, l-naphthyl isocyanate, 2,4-tolu-ene diisocyanate, m-phenylene diisocyanate, 1,4-tetramethyl-ene diiaocyanate, 1,6-hexamethylene diisocyanatff, 1,4-cyclo-hexyle~e diisocyanate, 1,5-tetrahydronaphtharene diisocyanate, trimethylhexamethylene diisocyanate, tris (4-isocyanatophen-yl), the ester of thionophosphoric acid, toluene diisocyanate-trimethylol propane adduct, the reaction product of toluene diisocyanate and hexamethylene diisocyanate (3:2), and the like. The choice of the isocyanate to be utilized depends on the type of polymer to be modified, and the end result -to be expected, as is known to those skilled in the art.
The isocyanate-modified polymers of this invention can be prepared by reacting the hydroxyl, amino or thio groups on the polymers with the organic isocyanates. The reaction is typically carried out in an organic solvent which is complete]y inert toward the organic lsocyanates, such as te-trahydrofuran, dioxane, acetone, methyl ethyl ketone, and like, at room temperature, or at reflux temperature. Usual , 106~073 catalysts for the isocyanate reaction, such as dibutyltin dilaurate, are optionally added.
A suitable method for preparing a lithographic printing plate is to dissolve the isocyanate-modified polymers and the light-sensitive naphthoquinone diazide derivatives in an organic solvent, such as acetone, methyl ethyl ketone, methyl cellosolve ,methyl cellosolve~acetate, tetrahydrofuran or mixtures thereof in various proportions, and to apply the solution onto a suitable base sheet or sub-strate, preferably an aluminum sheet. The coating may be applied, e.g. by immersion or casting and draining, or by casting and centrifuging off the excess of the solution, by brushing, by swabbing, by roller-coating, or by any other method Xnown of application. The coating thus applied i9 then dried at room temperature or at an elevated temperature.
The coating solution ~hould contain at least about one part by weight of each of the light-sensitive compounds and the isocyanate-modified polyméric materials per 100 parts of the organic solvent, desirably about 2 to about 20 parts, and preferably about 3 to about 10 parts. The isocyanate-modified polymers can be used in an amount of up to about 10 times by weight of the amount of the light-sensitive compounds.
Desirably, the polymer is used in an amount of at least about 0.1 part by weight per part of the light~sensitive compound, and, preferably, in an amount of about 0.5 to about 5 parts by weight of polymeric material per part of light-sensitive com-pound.
It is desirable to include in the coating a small -7_ ~ ,~ AZ 745 amount of indicator to show the image area on the developed plate, for example, a dye that changes color upon light ex- ¦
posure or upon decomposition of the naphthoquinone diazide '-~
compounds, such as diethylaminoazobenzene, thus making it easy to distinguish the image area from the non-image area immediately upon exposure of the plate.
Significantly improved lithographic printing plates can be obtained by modifying a phenol-formaldehyde resin, such asthe "AlnovolPN 430" ~ widely usedin priora~, with organic isocyanates. The amount of the isocyanates is de-sirably in the range of 0.1 part to 60 parts by weight per 100 parts by weight of the resin, if a monoisacyanate is u~ed; and from 0.1 part to 15 parts by weight per 100 parts by weight of the resin, if a diisocyanate or polyisocyanate is used, The pr~ferred range is from about 2 to 35 parts by weight of monoisocyanate per 100 parts by weight of the re-sin, and from 0 1 part to 10 parts by weight of diisocyanate or polyisocyanate per 100 parts by weight of the resin. Lith-ographic printing plates, prepared with these isocyanate-modified phenol-formaldehyde resins in the coating formula-tions, show sub9tantially increa9ed pre99 run9, significant-ly improved adhesion, wear and abrasion resistance and great-er resistance to prolonged immersion in an alkaline-aqueou9 developer than the corresponding printing plates with unmodi-fied resin in the formulation, and yet are still easy to develop. Also, in those cases where the developsd plates are subjected to heat treatment at an elevated temperature suffi-cient to cause melting of the coating, it is observed that ~A

.. . . .

~6~073 ~
the number of pinholes and spots is greatly reduced, or completely eliminated.
The compositions of the diazo sensitizers and organic isocyanates used in the appended examples are given in the following Tables I and II, respectively. Table III gives specifications of the novolak resins used in the examples.
TABIE I
Diazo Sensitizers Diazo I 2,2' Bis lnaphthoquinone-(1,2)-diazide-(2)-~ulfonyl-hydroxy-(5)3-dinaphthyl-(l,l')-methane Diazo II 2,4-Bis- rnaphthoquinone-(1,2) diazide-(2J~
~ulfo~yl hydroxy-(S)]-dihydroxybenzophenone Diazo III Ester of naphthoquinone-(1,2)-diazide-(2)-sul~onic acid-(5) and 1,2,3-trihydroxybenzophenone Diazo TV Naphthoquinone (1,2)-diazide-(2) sulfonic-acid chloride (4) Diazo V Naphthoquinone-(1,2)-diazide-(2)-sulfonylhydroxy-(4)-phenylcumene TABLE II
Isocyanates 1. Trimethyl hexamethylene diisocyanate

2. Toluene diisocyanate trimethylol propane adduct

3. Reaction product of toluene diisocyanate and hexamethyl-ene diisocyanate (3:2)

4. Tris (4-isocyanatophenyl) ester of thionophosphoric acid

5. Butyl isocyanate

6. Tonco'~' 70(%)(0ctadecylisocyanate-Technical - Upjohn Co.)

7. Tonco 90(%)(Octadecylisocyanate-Technical - Upjohn Co.)

8. Cyclohexylisocyanate A~ 745

9. P-methoxyphenylisocyanate

10. Hexamethylene diisocyanate TABLE III
Alnovol Novolak Phenolic Resins _ novol No. Meltinq Point Acid No Densit P~ 320 83 - 88C 1 ca. 1.25 ;
PN 430 110-120C 1 1.2 The following examples illustrate preferred embodi- -ments of the invention and are not to be considered as limit-ing the scope of the present invention. Unle~s otherwise stated, percentages and parts are all by weight.
ExamPle 1 An electrolytically-roughened aluminum foil is coated, for example on a whirler, with a solution containing 6.5 parts of butyl isocyanate-modified phenolic resin and 2.2 p3rts of Diazo III in 100 parts of methyl cello~olve.
The coated aluminum foil is then dried, exposed to light under a positive master, developed with a 3.5 percent solu-tion of trisodium phosphate adjusted to pH 12.8 with sodium -20 hydroxide, rinsed with water and sub~equently made ready for printing by wiping with a 1 psrcent solution of pho~phoric acid. Prolonged immersion of the plate in the developer solution for 15 minutes caused practically no 1099 of the image. The plate was then run on a press, and showed no wear up to 65,000 impressions.
A butyl isocyanate-modified phenolic resin is prepared as follows:
100 parts of finely pulverized novolak (e.g. the product marketed under the trademark "Alnovol PN 430")is dissolved in 200 parts of tetrahydrofuran. 7.5 parts of butyl isocyanate and 0.5 part of dibutyltin dilaurate are added, The mixture is refluxed for 2 hours, then vacuum distilled, The residue is cooled down to room temperature, finally pulverized and then dried in a vacuum oven. The polymer melt temperature is 105C, The infra-red spectrum showed no isocyanate absorption at 2260 cm~l, Example 2 The procedure of Example 1 wos followed to prepare a lithographic plate with a coating containing the following-ingredients.
~ Parts Diazo III 2.2 "Tonco 70"_phenolic resin condensation pro-duct 6.5 Methyl cellosolve 100.0 5-(p-Diethylamino-benzylidene) rhodamine 0.2 The plate-was satisfa~ctorily exposed and developed as described in Example 1, and had a useful life of over 45,000 impressions.
A "Tonco 70"-modified phenolic resin is prepared as follows:
100 parts of finely pulverized novolak ("Alnovol PN 430") is dissolved in 200 parts of tetrahydrofuran. 7.5 parts of Tonco 70 (technical grade octadecyl-isocyanate marketed by the Upjohn Company, Polymer Chemicals Div., La-porte, Texas, U.S.A.) and 0.5 parts of dibutyltindilaurate 106~073 AZ 745 are added, The mixture is refluxed for 2 hours, 400 p3rts ~
of methanol is than added and the mixture is added dropwise - -to 3 liters of water, The precipitate is collected by fil-; tration, and then dried in a vacuum oven. The polymar melt temperature is 98C.
ExamPle 3 The procedure of Example 1 was followed to preparea lithographic plate with a coating containing the following ingredients:
Parts Diazo III 2.2 Cyclohexyl isocyanate-modified phenolic resin 6,5 Methyl Cellosolve ~ 100.0 4-diethylaminoazobenzene 0.3 The plate was satisfactorily exposed and developed as described in Example 1, and had a useful press life of over 45,000 impressions.
A cyclohexyl isocyanate-modified phenolic resin is prepared according to the general procedure described in Example 2.
Example 4 The procedure of Example 1 was followed to prepare a lithographic plate with a coating containing the following ingredients. -Parts Diazo III 2.2 P-methoxyphenyl isocyanate-modified phenolic resin 6.5 ~ AZ 745 Methyl cellosolve ~062073 loo.o 4-Diethylaminoazobenzene 0.3 , ,, ' The plate was satisfactorily exposed and developed ~' as described in Example 1, and had a useful press life of over ~,~
55,000 impressions.
A p-methoxyphenyl isocyanate-modified phenolic , regin i8 prepared according to the general procedure described in Example 2.
ExamPle S
, The procedure of Example 1 was followed to prepare '~
a lithographic plate with a coating containing the following ~, in,gred~ents. ' ,'~

Parts "' .
Diazo III 2.2 Hexamethylene diisocyanate-modified phenolic resin 6.5 Methyl cellosolve 100.0 ; ,, 4-Diethylaminoazobenzene 0.3 The plate i5 exposed to light under a positive ""
master, developed with a 2 percent solution of trisodium phosphate, rinsed with water and sub~equently made ready for printing by wiping with 1 percent solution of phosphoric acid. The developed plate is then exposed briefly to light ' and then heated to 250C in an oven for 10 minutes, The printing surface is found to be free of pinholes and spots.
A hexamethylene diisocyanate-modified phenolic resin is prepared as follows:
100 parts of finely pulverized novolak ("Alnovol P~ 430") is dissolved in 200 parts of tetrahydrofuran and 4 parts of hexamethylene diisocyanate and 0.5 part of dibutyltin ~13-106.'~ 73 dilaurate are added. The mixture is agitated at room tem- -perature until it is completely in solution. It is then set overnight. 200 parts of methyl alcohol is added to the ;
mixture. The solution i9 then added dropwise to 5 liters of water. The precipitate is collected by filtration and then dried in an oven. The polymer melt temparature is 110-145C.
In the following examples, diazo sensitizers, isocyanates, and novolaks are selected from Tables I-III, respectively. In addition, novolaks are reacted with isocyan-ates to form isocyanate-modified resins according to the for-mulas enumerated in Table IV, The general procedure for the preparation of resins 1 - 9 in Table IV, follows.
Example 6 In a 3-necked flask, equipped with a stirrer, reflux condenser and drying tube, tetrahydrofuran is introduced and then the appropriate novolak resin added in one or two por-tions. The isocyanate and four drops of cobalt naphthenate are added with concurrent heating *o 60C. The reaction time is three hours at 60C. Next, the solution i5 cooled to room temperature with continued stirring and stored until used.
TABLE IV
IsocYanate Modified Novolak Resins The resins are the products of the reaction of the ingredients shown. (All weights are in grams~

1. Alnovol PN 430 144.18 Butyl isocyanate 4 96 Toluene diisocyanate-trimethylolpropane adduct 1.86 .

^^ AZ 745 2. Alnovol PN 430 96.2 .
Diphenylmethan-4,4'-diisocyanate 2.5 -3. Alnovol PN32 0 173.0 Reaction product of toluene diisocyanate and hexamethylene diisocyanate ( 3: 2) 17.4 4, Alnovol PN 43 0 140.0 Toluene diisocyanate- ;
trimethylolpropane adduct6.56 -~

5. Alnovol PN 43 0 2 3 3 . O .~ ~;
Trimethyl hexamethylene diisocyanate 5 . 25 ~ -6. Alnovol PN 43 0 187.0 Reaction product of toluene diisocyanate and hexamethy-lene diisocyanate (3:2) 8.59 7. Alnovol PN 43 0 144 . O .
Tris (4-isocyanatophenyl) egter o~ thionophosphoric acid 4.65 8. Alnovol PN 430 144.18 Butyl isocyanate 4.96 9. Alnovol P~ 43 0 187.0 Toluene diisocyanate-trimethylolpropane adduct6.56 Exampie 7 Wire brushed aluminum was coated with a light-sensitive solution of the following composition:
3`0 0.5 g Diazo I
1. 5 g Diazo II
6.0 g Resin 1 0.07g Dimethylaminoazobenzene in a solvent mixture of 5 parts tetrahydrofuran, 4 parts of methylglycol, and 1 part of butyl acetate. A coating thickness of 2 g/m2 was obtained.

106~073 AZ 745 Exam~le 8 Mechanically brushed aluminum was coated with a light-sensitive solution of the following composition: .-0,5 g Diazo I .
1.5 g Diazo II
6.0 g Resin 2 0.1 g Crystal violet :
0.07g Dimethylaminoazobenzene - - -in the same solvent mixture, resulting in the same coating thickness aæ in Example 1.
Example 9 Wire brushed aluminum was coated with:
0,5 g Diazo I ~.
1,5 g Diazo II
6.0 g Resin 3 0.1 g Crystal violet 0,07g Dimethylaminoazobenzene, in asolvent mixture as in Example 7, to a coating thick-ness of 1.55 g/m2.
ExamPle 10 Wire brushed aluminum was coated with a solu~
tion of:
1.3 g Diazo III
0.7 g Diazo I
7,0 g Resin 4 0.1 g ~ Crystal violet 0.06g Dimethylaminoazobenzene as in Example 7.

10621)73 Example 11 ,.. .:
Wet brushed aluminum was coated with a solu- ~
,~, r tion of the following composition:
2.0 g Diazo II
0.5 g Diazo IV
8.0 g Resin 5 0.2 g EponlO01 ~ (ShellChemical Co bisphenol A-epichlorohydrin reac-tion product) 0.08g Crystal violet, in the previous solvent mixture. A coating thickness of 2.3 g/m2 was obtained.
ExamPle 12 Electrochemically grained, anodized aluminum was coated with the ~ollowing composition:
1.3 g Diazo V
0.65g Diazo I
7.8 g Resin 6 ~' 0.2 g Epon lOOi 0.045g Crystal violet O.09 g Diazo IV.
A coating thickness of 4.10 g/m2 was obtained.
The coatings of Examples 7-12 were imaged as follows:
They were exposed under a positive transparent pattern so that step 4 of the UGRA stepwedge was just clean when the coating was developed with an aqueous alkaline developer of U. S. 3,110,596. After a rinse with dilute phosphoric acid, the plate was mounted on an offset printing press.
~A~ ~

~ AZ 745 106~()73 Example 13 -An aluminum/copper/chromium trimetal plate was coated with the following composition:
2,5 g Diazo III
4.2 g Resin 7 ~ -0,84g Polyvinyl acetate, Hoechst AG - -0.17g Crystal violet, from the usual solvent mixture, resulting in a coating thickness of 1.9 g/m2.
The coating was exposed through a negative transparent pattern and developed with an aqueous alkali- ;
soluble developer. The developed plate was etched with 7 a mixture of sluminum and zinc chlorides containing phos-phoric acid. The residual coating was removed with an alcoholic solution of sulfuric acid.
Example 14 ~. i A dimensionally-stable polye~ter film was coated with the solution of the following, in the same solvent mixtures used in Example 7:
0.81g Diazo III
0.4 g Resin 8 0.4 g Zapon Fast Red (made by BASF) 0.4 g Zapon Fast Red BB
A coating thickness of 1 g/m2 resulted. After exposure, the coating was developed with a diluted aqueous alkali solution of phosphates and metasilicate salts.
_ample 15_ A copper foil-phenolic resin laminate, conven-.

,. : .

~ AZ 745 106~073 ~
tionally used for printed circuit manufacture, was coated with the following: `~
3.0 g Diazo III
10.0 g Resin 9 0.3 g Castor oil 0.5 g Methylviolet BB, ~
in the usual solvent mixture. After the customary exposure ~-and development with the solution of Example 14, the copper-board wa-~ etched with a concentrated ferric chloride solution.
Éxample 16 A dimensionally-stable polyester film was coated with the following:
3.5 g Diazo V
12.0 g Resin 10 3,0 g Copolymer of vinyl acetate and crotonic acid 5.0 g Polyglycol (mol. wt. 2000 - 4.5 g Terpolymer of n-hexylmethacrylate, methyl methacrylate, and methacrylic acid 0.05g Crystal violet ~ "
12.0 g PlexisolB-574 (low viscosity polyethylacrylate-4~/O solution [made by Roehm AG Darmstadt~) A cover foil of polyethylene was placed in contact with the dried coating. To make a printed circuit, the surface of a copper board was cleanedj the cover oil was stripped on and the coating surface laminated to the copper surface at about 120C; the polyester film was removed; and the transferred coating was post dried at 100C, exposed and developed in an aqueous alkaline developer having a pH

~A~
, . --19--.

_~ AZ 745 10f~;~073 :
of 13.6. The coating is well suited as an etch resist for copper with strong ferric chloride solutions and as a :
plating resist.
It will be obvious to those skilled in the art that many modifications may be made within the scope of the pres~nt invention without departing from the spirit thereof, and the invsntion includes 311 such modifications.

Claims (19)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A positive-working, light-sensitive coating composition com-prising at least one condensation product of an organic isocyanate and a phenolformaldehyde novolak resin, in admixture with at least one light-sensitive diazo compound selected from the group con-sisting of esters and amides of o-quinone diaides and mixtures thereof, said composition being soluble in aqueous alkaline de-veloper solution after exposure to light.

2. A composition in accordance with claim 1 wherein the ratio of isocyanate to novolak resin is within the range of about 0.1 to 60 parts by weight of isocyanate per 100 parts by weight of novolak resin.

3. A composition in accordance with claim 1 wherein the or-ganic isocyanate is selected from the group consisting of a diisocyanate and polyisocyanate and is present in the range of about 0.1 to 15 parts by weight per 100 parts by weight of novolak resin.

4. A composition in accordance with claim 1 wherein said organic isocyanate is a mono-isocyanate.

5. A composition in accordance with claim 4 wherein the ratio of isocyanate to novolak resin is within the range of about 0.1 to 60 parts by weight of isocyanate per 100 parts by weight of novolak resin.

6. A composition in accordance with claim 5 wherein the ratio of mono-isocyanate to novolak resin is within the range of about 2 to 35 parts by weight of mono-isocyanate per 100 parts by weight of novolak resin.

7. A composition in accordance with claim 1 wherein said condensation product is present in the range of about 0.1 to 10 parts by weight per part by weight of said light-sensitive diazo compound.

8. A composition in accordance with claim 1 wherein the developer is an aqueous alkaline solution.

9. A composition in accordance with claim 1 wherein the developer is an organic solvent.

10. A composition in accordance with claim 1 wherein the developer solution is a mixture of an aqueous alkaline solution and an organic solvent.

11. A light-sensitive material comprising a supported, positive-working, light-sensitive coating composition comprising at least one condensation product of an organic isocyanate and a phenol-formaldehyde novolak resin, in admixture with at least one light-sensitive diazo compound selected from the group consisting of esters and amides of o-quinone diazides and mixtures thereof, said composition being soluble in aqueous alkaline developer solution after exposure to light.

12. A light-sensitive material in accordance with claim 11 in which the organic isocyanate is a mono-isocyanate.

13. A material in accordance with claim 11 wherein the material is a printing plate.

14. A material in accordance with claim 13 wherein the support is an aluminum plate.

15. A material in accordance with claim 11 wherein the material is a photoresist.

16. A material in accordance with claim 11 wherein the support is an aluminum/copper/chromium trimetal plate.

17. A material in accordance with claim 11 wherein the support is a copper foil-phenolic resin laminate.

18. A material in accordance with claim 11 wherein the support is a copper board.

19. A method which comprises exposing a supported, light-sensitive coating composition to light under a pattern and devel-oping the resulting image with an aqueous alkaline solution and/or organic solvent which removes the light-exposed areas of the coating, said coating comprising at least one condensation product of an organic isocyanate and a phenol-formaldehyde novolak resin, in admixture with at least one light-sensitive diazo compound selected from the group consisting of esters and amides of o-quinone diazides and mixtures thereof.