EP0198058A1

EP0198058A1 - Photosensitive polymers, preparation thereof and film-forming compositions containing them for photoengraving

Info

Publication number: EP0198058A1
Application number: EP19850905412
Authority: EP
Inventors: Gérard CHIRON; Guy Levesque
Original assignee: Centre National de la Recherche Scientifique CNRS
Current assignee: Centre National de la Recherche Scientifique CNRS
Priority date: 1984-10-29
Filing date: 1985-10-29
Publication date: 1986-10-22
Also published as: FR2572408A1; FR2572408B1; JPS62501036A; WO1986002743A1

Abstract

Polymères filmogènes photosensibles obtenus par action d'agents alkylants, tels que halogénures ou sulfates d'alkyle et de benzyle, sur des dérivés d'alcools polyvinyliques, Ces derniers résultent de l'estérification de l'alcool par des acides carboxyliques ou sulfoniques comportant un groupe azido ou azidosulfonylphényle, telle que des fonctions acides libres soient présentes. L'estérification a lieu avec une aminopyridine comme catalyseur. Ces polymères sont utilisés dans des compositions pour photogravure sur métaux.Photosensitive film-forming polymers obtained by the action of alkylating agents, such as alkyl and benzyl halides or sulfates, on derivatives of polyvinyl alcohols, the latter result from the esterification of the alcohol by carboxylic or sulfonic acids comprising a azido or azidosulfonylphenyl group, such that free acid functions are present. The esterification takes place with an aminopyridine as catalyst. These polymers are used in compositions for photoengraving on metals.

Description

Photosensitive polymers, their preparation and film-forming compositions containing them for photoengraving.

The present invention relates to photosensitive polymers, derived from a polyvinyl alcohol, their preparation process and the film-forming compositions which contain them, usable in the chemical photoengraving of metals.

Cellulose azidophthalates and polyvinyl alcohols, acetylated or not, have been described in patents US-A 2948610 and US-A 3002003, issued respectively on August 9, 1960 and September 26, 1961. US patent 2948610 relates to a photographic reproduction process consisting in exposing a film-forming polymer, soluble in an aqueous basic medium or in an organic solvent and which will be insolubilized by crosslinking with light, then in dissolving the unexposed areas in an optionally organic ammoniacal solution. Among the polymers mentioned are polyvinyl alcohol derivatives comprising from 10 to 1Θ0% of basic units:

in which R is H or COOH, the latter alone being soluble in basic medium.

Patent US 3002003 also describes film-forming polymers containing N ₃ groups and in particular those resulting from the esterification of a polyvinyl alcohol with an azidophthalic anhydride. These compounds are reputed to be particularly advantageous because of their solubility in alkalis, even before their crosslinking by light. The Applicant has found that these polymers were stable in an oxidizing medium and could thus be used in photoengraving on metals, which was not shown in the prior documents.

In current photogravure processes, a- near exposure to light, through the chosen mask, of the metal plate coated with the photosensitive film-forming composition and the elimination by dissolution of the non-crosslinked areas, the exposed metal is attacked, either by an acid oxidizing solution, in particular of ferric perchloride for copper plates, or by a basic oxidizing solution, such as that used in the Endura-Etch * process (HUNT-CHEMICALS) and described in FR- A 2 493 330.

However, the Applicant has found that, if polyvinyl hydrogen phthalates carrying azide groups of the type of those previously described, have good film-forming properties and resist oxidizing agents, they have the drawback of not swelling. negligible after crosslinking during the development operation, that is to say when removing the non-crosslinked polymer with a solvent; this swelling weakens the film formed; moreover, and above all, these polymers cannot be used in an etching process in a basic medium since even the crosslinked polymer would then be dissolved in the etching bath.

The present invention eliminates these drawbacks; in addition, the new photosensitive polymers give particularly flexible films. which makes it possible to reduce the amounts of plasticizer in the film-forming compositions, and of prolonged stability so that the metal plates coated with these compositions are preserved for quite a long time without alteration.

The invention relates to photosensitive film-forming polymers, derived from polyvinyl alcohols, for example partially esterified with acids with a phenyl ring carrying a group -N ₃ or -S0 ₂ N_, the acids being able to be:

1) monoacids, such as benzoic acids of formula:

N_ S0 ₂ _ ₃

2) the sulfonic acids of formula:

3) kinetic acids of formula

NOT,

in which R represents H, an alkyl group

^C l *** ^C 4 ' ^a halogen and, in these first three cases, the polyvinyl alcohol is also esterified with a phenylcarboxylic acid, such as the phthalic acids of formula I: in which R represents H, halogen, O ₂ , C 1 to C alkyl. and n is 0 to 4,

4) diacids, such as phthalic acids of formula:

in which R represents H or a C 1-6 alkyl group. and in this case, the polyvinyl alcohol may optionally be further esterified with a phenylcarboxylic acid, such as the phthalic acids of formula I, cinnaic acid, and furylacrylic acid.

The polymers according to the invention result from the action of an alkylating agent on these partially esterified polyvinyl alcohols.

The starting polyvinyl alcohols have molecular weights between 1000 and 100,000. They can result from the hydrolysis of the corresponding polyvinyl acetates; this hydrolysis can be partial, in which case the starting polyalcohols are partially acetylated; compounds having up to 60% of acetylated hydroxyl functions are suitable, but those having from 10 to 20% of acetylation are preferred.

The amount of ester groups having azido functions is not critical; it will be chosen to ensure good sensitivity to the photosensitive composition and a moderate cost price, knowing that the azido derivatives are expensive. It is generally preferred to block approximately 20% of the OH functions of the starting polyvinyl alcohol by esterification with such groups. Insofar as only part of the OH functions is thus blocked, the alcoholic polymer is further esterified with a phenylcarboxylic diacid of formula I. This acid is generally used in an amount of 1 to 4 times (in moles) that of l acid carrying azido groups.

The alkylation reaction is carried out with an alkylating agent chosen from C 1 -C 4 alkyl or benzyl halides or sulfates. Particularly preferred (CH ₃ ) ₂ S0 .. The alkylation is carried out in an aprotic solvent such as dimethylformamide or dimethyl acetamide, di ethyl sulfide, tetrahydrofuran or dio-xane, acetone or cyclohexanone, and in the presence of a base low, such as tertiary, such as triethylamine, sodium acetate or mixtures thereof. Under these conditions, there is esterification of a part of the carboxylic acid functions of the groups of formula I fixed on the polymer as well as etherification of a small part of the free hydroxy¬ functions of the. polyvinyl alcohol chain. According to the invention, 40 to 90% of the acid functions can be blocked in the form of esters, and in general, more than 80% of these functions will be blocked, to limit the solubility and swelling in a solvent medium, particularly at basic pH. It is known that the esterification reactions of polyvinyl alcohols are quite difficult and it is another advantage of the invention to be able to carry out es¬ terification at room temperature in the presence of a small amount of a catalyst, in general expensive. According to the invention, polyvinyl alcohol, for example whether acetylated or not, and the chloride or anhydride of the acid chosen, are dissolved in a polar aprotic solvent, such as dimethylformamide, dimethylsulfoxide, hexamethylphosphoramide, and are introduced into the medium. reaction of 0.5 to 3 mol%, relative to the phenylcarboxylic acid derivative, of an aminopyridine and at least one equivalent in mol, relative to the suitable acid derivative, of a weak base, such as a tertiary amine - such as triethylamine, diisopropylamine - such as an alkali carbonate - such as Li ₂ C0 ₃ , Na ₂ C0 ₃ , NaHC0 ₃ , such as an alkaline carboxylate such as CH ^ COONa - or a mixture thereof . Particularly preferred is 4-dimethylamino pyridine and 4-pyrrolidino pyridine, and as the weak base triethylamine or sodium acetate.

The preferred hydrogen phthalate is that resulting from the reaction of a weakly acetylated polyvinyl alcohol, approximately 10%, with a mixture in the ratio approximately 1/3, in moles, of azidophthalic anhydride and substituted phthalic anhydride or no and such that the starting reaction medium contains approximately 0.5 mole of phthalic anhydrides per OH function of polyvinyl alcohol.

Another object of the invention consists of the film-forming compositions containing at least one of the photosensitive polymers previously described, preferably in combination with a photosensitizer and a plasticizer usually used in these compositions, the whole being in solution in a solvent. Among the volatile solvents of the polymer, mention may be made of tetrah drofuran, acetone, alcohols, onoethers or diethers of glycol and diethylene glycol, methylene chloride, trichloroethane, and their mixtures. The concentration of photosensitive solutions will depend on the molecular weight of the polymer, its degree of esterification, of the nature of the coating equipment, but will generally be between 10 and 45% (weight / volume). The thickness of the deposited layer will be between 0.5 and 10 μm approximately, which will correspond to a deposit of 0.5 g to approximately 5 g of polymer per square meter of surface.

As mentioned previously, these film-forming compositions are particularly useful for the photo-etching of metals by conventional methods, given their photoreactivity, their adhesion qualities, whatever the treatment medium and their cost. And unlike non-alkylated intermediate polymers, they are particularly suitable for the preparation of printed circuits, since very fine lines, 0.2 mm wide, and 0.05 mm apart, can be engraved on a copper plate.

In what follows, there are described examples of embodiment and implementation of the invention. EXAMPLE 1 Esterification of a Polyvinyl Alcohol with Different Phthalic Acids: a) A solution is prepared, in 30 ml of dimethyl sulfoxide, of 2.45 g of polyvinyl alcohol of molecular weight approximately 10,000, 12% acetylated, pro ¬ product sold by Rhône-Poulenc under the brand Rhodoviol ^, and the reference 4/125. Then introduced into the solution 3.5 ml of triethylamine, 70 mg of 4-dimethylamino pyridine, 1.57 g of 3-azido phthalic anhydride and 2.47 g of phthalic anhydride. After 2 hours at room temperature, with stirring, the reaction medium is poured into 300 ml of water containing 20 ml of methanol and the solution is acidified by addition of a solution of N hydrochloric acid; 5.5 g of final product precipitate. After drying, the polymer thus obtained contains 3.2 illiëquivalents of acid per gram. b) 2.45 g of Rhodoviol ^ 4/125 are dissolved in 30 ml of dimethyl sulphoxide and 3.5 ml of triethylamine, 70 mg of dimethylaminopyridine, 1.19 g of 3-phthalic anhydride, 0.925 g of phthalic anhydride and 2.36 are introduced into the solution. g 3-phthalic azido anhydride. After treatment as in a), 5.8 g of a polymer are isolated which contains 3.3 meq / g of acid function.

This polymer adheres particularly well to a metal surface due to the presence of the NO ₂ groups. c) Using the procedure described in a), a more hydrophobic polymer than the previous ones is prepared from 2.45 g of Rhodoviol® 4/125, 0.945 g of 3-phthalic azido anhydride, 0.71 g of tetrachlorophthalic anhydride, 2.59 g of phthalic anhydride, 3.5 ml of triethylamine and 70 mg of 4-dimethylamino pyridine. ^* d) To a solution of 2.45 g of Rhodoviol ^ 4/125 in 40 ml of diethylsulfoxide, 1.84 g of 3-benzoyl azidosulfonyl chloride, 2.6 g of phthalic anhydride are added , 4 ml of triethylamine and 100 mg of dimé¬ thylamino-4 pyridine, the isolation of the final product is done as above. Example 2: Esterifications of a polyvinyl alcohol followed by the reaction with an alkylating agent: a) A solution of 95.7 g of Rhodoviol ^ - ^{** 1} 4/125 is introduced into 1100 ml of dimethylsulfoxide, 67 ml of triethylamine, 40 g anhydrous sodium acetate, 1 g. of 4-dimethylamino pyridine and 109 g ^* of phthalic anhydride and 46 g of 3-azido phthalic anhydride. After 4 hours, with stirring, at room temperature, 37 ml of dimethyl sulfate are introduced into the medium. The mixture is stirred for 16 h 30 at room temperature, then 800 ml of methanol are introduced and dropwise, the solution is poured into 5 liters of acid. of 0.6N hydrochloric acid. The precipitate formed is isolated and then dried. 248 g of final polymer are thus obtained which carries 3.5 milliequivalents of phthalyl groups per gram of starting product and therefore approximately 35% of the acid functions have been methylated. b) The same mixture is prepared as in a) in dimethylsulfoxide, but after 5 hours of agitation at room temperature 800 ml of methanol are introduced into the medium and acidified by addition of hydrochloric acid. The precipitate formed is isolated and dried, then 200 g of it are dissolved in 400 ml of dimethyl sulfoxide containing 103 ml of triethylamine. 70.3 ml of dimethyl sulphate are then added and the mixture is stirred at room temperature for 3 h 30 min. 600 ml of acetone, 200 ml of methanol, 1 l of water are then introduced into the medium. then 125 ml of concentrated hydrochloric acid (12 N) with vigorous stirring. The final product precipitates. After drying, 205 g of product are obtained in which 84% of the acid functions of the phthalic groups are methylated. c) 1 g of polyvinyl alcohol hydrogen phthalate prepared as in the first part of Example 2b is dissolved in 1 ml of diethylsulfoxide in the presence of 1 ml of triethylamine. Then introduced into the medium 0.2 ml of benzyl chloride and left for about 1 night with stirring. The final product precipitates by acidification of the medium. After purification by dissolving in 15 ml of acetone and precipitation by addition in 100 ml of 1N hydrochloric acid, then drying, it contains 1.48 milliequivalents of acid functions / g, which means that about 50% of the acid functions of phthalate groups have been esterified. EXAMPLE 3 Photosensitive compositions for the photogravure of copper: a) 100 g of polymer obtained are dissolved as in 10.

Example 2 a) in 400 ml of a 1: 1 (v / v) mixture of butyl glycol and ethyl glycol and 4 g of nitroacenaphthene and 5 g of a plasticizer based on polyvinyl methyl ether are added marketed under the brand name Lutonal ^ - 'by BASF. Coated copper coated plates

2 (35 / u thick), approximately 2 m in surface, with this solution, so that approximately 2 g of dry matter are deposited per square meter of surface, then the film is dried by passing through a tunnel heated to around 60 ° C. After exposure of the plate thus treated, through a mask, for 4 minutes, under ultraviolet radiation of wavelength 350 to 420 mm, it is developed by treating with an aqueous basic solution of pH less than 10 and containing 2% of trisodium phosphate. After rinsing with water, the copper is etched by attack with a solution of ferric perchloride of concentration 200 g / 1 and for a contact time of the order of a few minutes.

After rinsing, stripping, or elimination of the crosslinked polymer, is carried out by. treatment with a sodium metasilicate solution of concentration 10 to 20 g / 1. Under these conditions, the resolution - that is to say the minimum distance of the lines that can be engraved is 0.05 mm for a line width equal to this distance. b) Dissolve 60.4 ^'g of the polymer obtained in Example 3 b) in 225 ml ethylglycol with 3 g of ni- tro-5 acenaphthene and 1 g of Lutonal ^v -'.

The coating of the copper plates is effected as before at the rate of 2 g of polymer per 2 m of plate. After sunshine, development is carried out by treatment with a solvent mixture of ethyl¬ glycol and ethanol (2/1 - v / v).

The etching is carried out according to the alkaline etching process with continuous regeneration, known under the name of Endura-Etch®, and marketed by HUNT CHEMI- CALS. The oxidizing baths have a pH of 8 to 9 and the treatment temperature is between 43 and 54 ° C. Under these conditions, the crosslinked polymer remains perfectly adherent. Stripping is carried out by a 1: 1 mixture

(v / v) acetone / ethanol.

The resolution is 0.05 mm.

Claims

12. CLAIMS

1. Photosensitive film-forming polymer, derived from a polyvinyl alcohol partially esterified with acids chosen from carboxylic acids or sul-

5 foniques comprising an azido or azidosulfonylphé¬ nyle group, in which case the polyvinyl alcohol is further es¬ terified by a phenylcarboxylic acid, and among the azido and sulfonylazido-phthalic acids, in which case the polyvinyl alcohol is, optionally in addition, 10 esterified with a phenylcarboxylic acid, photosensitive polymer characterized in that it results from the ac¬ tion of an alkylating agent on said partially esterified polyvinyl alcohol.

2. Polymer according to claim 1, characterized in that from 1% to 25% of the hydroxyl groups of

'the starting polyvinyl alcohol are acetylated.

3. Polymer according to one of claims 1 or 2, characterized in .this that the alkylating agent ^is a logénure- ha- sulfate or alkyl C, -C ₅ or benzyl.

4. Polymer according to any one of the preceding claims, characterized in that the phenylcarboxylic acid is chosen from phthalic acid, 3-phthalic acid or tetrachlorophthalic acid.

25 - 5. Process for the preparation of a compound according to any one of the preceding claims, characterized in that: a) reacting on polyvinyl alcohol, partially acetylated or not, in an aprotic solvent

30 that polar, a chloride or anhydride of carboxylic or sulfonic acid or of a mixture of acids in the presence of - a catalyst composed of a weak base and of a amiopyridine of formula I: _.

in which R- and R ₂ represent independently a C 1 -C alkyl group or taken together with N represent a C ₅ -C heterocycle. b) An alkylating agent is reacted on the hydrogenophthalates obtained, in the presence of a base.

6. Process according to claim 5, characterized in that the catalyst is composed of a mixture of atopyridine of formula I and of a base chosen from tertiary amines, carbonates and alkaline carboxylates.

7. Photosensitive film-forming composition for photoengraving on metals, characterized in that it comprises at least one polymer according to any one of claims 1 to 4.