GB2155487A - Catalyzed urethanation of polymers - Google Patents

Abstract

Bicyclic tertiary amines are used as catalysts in the manufacture of urethane-modified phenol- formaldehyde resins. The products are especially useful in the manufacture of photosensitive materials, for example, positive-acting lithographic plates.

Description

SPECIFICATION Catalyzed urethanation of polymers This invention relates to a process for the manufacture of urethane-modified phenolic resins, to resins produced by the process and to compositions, especially light-sensitive compositions, comprising the resins. More especially, the invention provides an improved catalytic process for the manufacture of the resins.

It has been proposed to use 1,4-diaza-bicyclo [ 2,2,2 ] octane, also known as triethylenediamine, as a catalyst for preparing polyurethane foams, as shown in U.S. Patent 3,770,671 and 3,598,771. It has also been proposed to synthesize polyurethanes by reaction of isocyanates with organic hydroxy compounds using triethylenediamine, or 1-aza-bicyclo [2,2,2] octane, also known as quinuclidine, as a catalyst, as shown in U.S. Patents 3,167, 518, 3,036,121 and 2,939,851.

The reaction of isocyanates with simple hydroxy compounds in the presence of triethylenediamine or quinuclidine as catalyst proceeds extremely slowly. Accordingly, such processes have not been used in practical commercial production. Metal alkyl catalysts in general, especially organotin compounds, and dibutyltin dilaurate (DBTDL) in particular, are known to accelerate urethanation as shown in U.S. Patents 4,124,573 and 3,853,795. Studies have established that DBTDL is a superior catalyst for this reaction. Such studies have appeared in Kirt-Othmer, Encyclopedia of Polymer Science and Technology, 2nd ed., Vol. 1 1963, Johm Wiley a Sons, Inc. and in Advances in Urethane Science and Technology, Vol. 3. 1974, Technomic Publishing Co..The literature cites the merits of using the metal complexes alone or in admixture with tertiary amines which synergistically enhace the catalytic activity. In all cases, the catalytic rate of the metal complexes has been greater than that of the tertiary alicyclic or aliphatic amines as shown by S. L. Reegen and K. C. Frisch, Catalysis in Isocyanate Reactions, Adv. in Urethane Sci. 8 Tech, Vol. 1, 1971; G. Huynh-Ba G. R. Jerome, Urethane Chem. & pp., Paper 16, p.

205, 1981. The relative superiority of the activity of DBTDL compared to triethylenediamine for urethanation from isocyanates and hydroxy compounds has been shown to be from almost 2:1 up to approximately 840: 1, depending upon the selection of the components reacted. In many applications, a rapid reaction is desirable and necessary. For example, the commercial preparation of polyurethane foam depends on a rapid, one-step procedure. The metal catalysts, in particular the tin compounds such as DBTDL, are used throughout the industry for this purpose. It has now surprisingly been found that in the process for the manufacture of urethanemodified phenolic resins, bicyclic tertiary amines are effective catalysts, indeed more effective than the organotin catalysts.

The present invention accordingly provides a process for the manufacture of urethane modified phenolic resins, which comprises reacting an organic isocyanate and a phenol förmaldehyde resin in the presence of a catalytic amount of a bicyclic tertiary amine.

Advantageously each ring of the amine is six-membered. Triethylenediamine and, especially, quinuclidine are preferred bicyclic tertiary amines. The reaction is advantageously carried out in a dispersion, more especially a solvent, which is preferably non-hydroxylic and moisture-free. In the urethane modification of phenol-formaldehyde resins, according to the invention, the bicyclic tertiary amines save time, for example, both in preparing batches of solid modified resins and in the in situ formation of these resins for an end-use coating solution application. In the latter case, the phenol-formaldehyde resin may, for example, be dissolved in a non-hydroxylic solvent and the appropriate percentage of isocyanate added along with the catalyst.As soon as the available isocyanate has reacted, the remaining ingredients of the coating solution may be added and the solution used for coating without direct isolation of the modified resin. The reaction time between the resin and the isocyanate is important to the overall batch preparation time. The efficiency of the bicyclic tertiary amines as catalysts results in cost saving in plant equipment use. In addition, the amine catalysts are considerably less expensive on a weight basis, resulting in further cost saving. A further advantage of the bicyclic tertiary amines is that partially or completely modified phenolic resins having specific functional properties may be made more rapidly and efficiently by this process by providing an appropriate urethane content.

The polymeric materials prepared in accordance with the present invention by urethane modification of phenolic resins have improved resistance to alkali or solvent attack because of the partial reaction to the phenolic hydroxyl function. The modified resins may be used, for example, as varnishes, lacquers or binders, alone or in conjunction with other suitable polymeric materials. They are especially useful as carriers for light-sensitive compounds, for example, diazo compounds, usually quinone diazides, in a light-sensitive composition, as revealed in U.S Patent 4,189,320, the disclosure of which is herein incorporated by reference. Such light-sensitive compositions are useful in the preparation of positive-acting lithographic plates, based on oquinione diazides.Such lithographic plates may, for example, be prepared by dissolving a urethane-modified phenolic resin and a light-sensitive naphthoquinone diazide derivative in an organic solvent, for example, acetone, methyl ethyl ketone, methyl Cellosolve, methyl Cellosolve acetate, tetrahydrofuran or mixtures thereof in suitable proportions, and applying the solution onto a suitable base sheet or substrate, preferably an aluminium-containing sheet. ("Cellosolve" is a trade mark!) The coating may be appliedby any appropriate method, for example, immersion, casting and draining, casting and centrifuging the excess solution, brushing, swabbing or roller coating by means well known in the art. The coating is then dried at room temperature or at an elevated temperature.

The coating solution should preferably contain at least about one part by weight of the lightsensitive compounds per 100 parts of the organic solvent and at least about one part by weight or the urethane-modified resin per 100 parts of the organic solvent, more preferably about 2 to about 20 parts and most preferably about 3 to about 10 parts. The urethane-modified phenolic resin may be used in an amount of up to about 10 times by weight of the amount of the lightsensitive compounds. Desirably, the resin is used in an amount of at leasyt about 0.1 part by weight per part of the light-sensitive compound, and, more preferably, in an amount of from about 0.5 to about 5 parts by weight of polymeric material per part of light-sensitive compound.

Lithographic printing plates prepared with urethane-modified phenolic resins in the coating composition show substantially increased press runs, significantly improved adhesion, wear and abrasion resistance and greater resistance to prolonged immersion in an alkaline aqueous developer than the corresponding printing plates made with the corresponding unmodified phenol4ormaldehyde resin in the formulation, and yet remain easy to develop as demonstrated in U.S. 4,189,320. Additionally as shown in U.S. 4,189,320, in those cases where the developed plates are subjected to a burning-in or heating treatment at the elevated temperatures known in the art, undesirable pinholes and spots are greatly reduced in number or completely eliminated.

As mentioned above, it has been found that in reacting isocyanates and phenolic resins to produce the urethane-modified polymers, the catalytic activity of triethylenediamine and quinuclidine is, surprisingly and unexpectedly, much greater than the catalytic activity of DBTDL in terms of the speed of reaction. As shown below, DBTDL is a superior catalyst when isocyanates are being treated with simple alcohols or low molecular weight hydroxy compounds as compared to triethylenediamine or quinuclidine. This fact is also shown in U.S. Patent 3,853,795 and in Advances in Urethane Science and Technology, Vol. 3, 1974, Technomic Publishing Co. When isocyanates are reacted with phenolic resins, however, a different result is noted.

The phenolic resins utilized in the process of the present invention are preferably phenolformaldehyde resins and, most preferably, cresol- or phenol-formaldehyde resins of the novolak or resole type. Exemplary of the novolak-type resins useful in this process are Alnovol PN-429 and Alvonol PN-430, both manufactured by Hoechst AG, West Germany, and cresol-formaldehyde copolymers manufactured by Polyrez Corporation of Woodbury, New Jersey, U.S.A.

Exemplary of the resole-type resins useful in the process of this invention is Schenectady SP 1 34 manufactured by Schenectady Chemical, Incorporated of Schenectady, New York, U.S.A.

The phenolic resin utilized in the present invention may be present in the range of from 0.1 % up to 100% by weight of the solvent depending upon the solubility desired for the final product.

The organic isocyanate may be any suitable organic monoisocyanate or polyisocyanate, including isocyanate polymers. Exemplary of organic isocyanates useful in the practice of this invention are butyl isocyanate and hexyl isocyanate and Mondur HC polyisocyanate available from Mobay Chemical Company of Pittsburgh, Pennsylvania, U.S.A. Mondur HC is an aliphatic/aromatic polyisocyanate copolymer dissolved in ethylene glycol diacetate and xylene.

The isocyanate group content of Mondur HC is 10.9-12.1%. When a polyisocyanate is used, cross-linking in the mqdified resin may occur because the multi-functional isocyanate groups may react with hydroxy groups from two different polymer chains. The concentration of the organic isocyanate or polyisocyanate may, for example, be from 0.1 % up to 100% by weight of the amount of the phenolformaldehyde resin present, preferably from about 0.1 % to about 20% and, most preferably, from 0.1% to about 10%. In a preferred embodiment, the isocyanate is present in an amount of 8% by weight of the resin.

The catalysts of the present invention are bicyclic tertiary amines, and are, particularly, 1,4diaza-bicyclo [ 2,2,2 ] octane, also known as triethylenediamine, andl-aza-bicyclo [ 2,2,2 ] octane, also known as quinuclidine.

The catalyst may be present at a concentration of from about 0.1 % of the phenolformaldehyde resin up to the solubility limit of catalyst in the system, and preferably from about 1 % to about 10% by weight of the phenol-formaldehyde resin.

The urethane-modified polymers described herein may be prepared by reacting the hydroxyl groups on the phenolic resin with the organic isocyanate. The reaction is preferably run at ambient temperatures, but reaction temperatures from ambient to reflux are possible. Heating is optional and necessary only to increase reaction rate. High temperatures, however, are hazardous, especially when low flash point solvents such as tetrahydrofuran are used. Secondary reactions may also occur at elevated temperatures. All reagents are desirably substantially waterfree. The solvent is advantageously a non-hydroxylic, moisture-free solvent, for example, tetrahydrofuran (THF) or n-butyl acetate.

In the preferred process of this invention a novolak or resole resin at a concentration of 1-30% by weight of the solvent is reacted with a mono isocyanate or a polyisocyanate at a concentration of 8% by weight of the resin, in the presence of the triethylenediamine or quinuclidine at a concentration of 3% by weight of the resin in the solvent tetrahydrofuran.

The mechanism by which the catalysts used in the process of this invention achieve their unexpected activity is presently known.

Catalysts are often chosen specifically to give desired functional properties. These result from the property distribution of products obtained from a reaction using one catalyst as opposed to another. Certain catalysts favor dimerization or trimerization of the isocyanate, others favor the reaction with water. In order to confirm that the catalysts of the present invention result in the same product distribution as the metal catalysts of the prior art, experimental batches are made and tested. The results indicate that products isolated from either the metal- or amine-catalyzed reactions were comparable by all measurable criteria. This is demonstrated by the following: Samples of urethane-modified cresol formaldehyde resin prepared with DBTDL and triethylenediamine are each isolated to verify that the products are comparable.The procedure used is a follows: Two solutions, A and B, each containing 0.1 mole (based on monomeric unit) of cresol formaldehyde resin are prepared in 100 ml dry tetrahydrofuran (THF). 0.1 mole hexyl isocyanate is added to each. To solution A, 1g triethylenediamine is added. To solution B, 1g DBTDL is added. Solutions are stirred under ambient conditions overnight. IR spectra indicate that no residual N = C = 0 remains, indicating 100% reaction.

Each reaction product is isolated in the same way. Excess THF is distilled off under vacuum.

The resultant syrup is taken up in a minimal amount of acetone and then poured slowly into water in a blender. After blending for 1 minute, the water is decanted and fresh water added and the cycle repeated. The solids are filtered off isolating 85-90% yields in each case.

IR spectra as KBr discs of the product obtained from the individual reactions with the two catalysts respectively are superimposable on each other. GPC curves of the two reaction products show the expected shift to higher molecular weight fractions with only slight differences in the overall spectra.

In each of the following examples, tetrahydrofuran is placed in a brown bottle provided with a magnetic stirrer. To this is added the phenol4ormaldehyde resin with rapid agitation until the resin is completely dissolved. The bottle is capped to prevent evaporation. The isocyanate is then added, followed by the catalyst. An aliquot of the solution is placed in an infrared cell (Nacl IR solution cell) and scanned between 2500 and 2000 cm - in an infrared spectrophotometer to note the original concentration of isocyanate as evidenced by the absorption peak nominally at 2250 cm-' (t=0).

The reaction is monitored by taking an aliquot in an NaCI IR solution cell (0.20mm) and scanning the isocyanate stretch region in the infrared (2500-2000 cm - ') until the peak disappears. This indicates a complete reaction. The isocyanate stretch at approximately 2250 cm 1 is monitored against time and the time needed for reaction completion is estimated from this absorption. Complete IR scans are run when the reaction is complete to verify the expected urethane absorption peaks.

The urethane-modified resin thus produced can either be isolated or used directly in situ as discussed above. To isolate the product, excess solvent is evaporated off by heating slightly under reduced pressure on a rotary evaporator in a 100 ml round bottom flask. The viscous residue is poured into 100 ml of rapidly agitated cold water using a blender. The solids can then be filtered and dried under high vacuum for subsequent use.

More commonly, the urethane-modified resin may be used directly in situ. In this case, the solution is used as it is with further ingredients added to prepare photosensitive coating solutions for aluminum or polyester film applications useful for lithographic purposes.

The following examples illustrate the invention.

EXAMPLE I As a control, 0.25g of hexyl isocyanate is mixed with 0.05g of DBTDL in tetrahydrofuran and monitored for loss of isocyanate. If water is present in the system, there should be a loss of isocyanate as a result of the following reaction:

After 24 hours, little change is observed in the IR absorption between 2500 and 2000 cm-'.

EXAMPLE la As a further control, 0.25g of hexyl isocyanate is mixed with 0.05g of triethylenediamine in tetrahydrofuran and monitored for loss of isocyanate. After 24 hours, little change is observed in the IR absorption between 2500 and 2000 cm-' EXAMPLE II Hexyl isocyanate is treated with benzyl alcohol in the presence of DBTDL in 30 ml of tetrahydrofuran in the following proportions: 3.0g benzyl alcohol 0.3g DBTDL 3.4g hexyl isocyanate When IR scans indicate that the reaction is complete and the expected urethane absorption peaks are present, the urethane product is isolated.

EXAMPLE lla The same components as in Example II are caused to react in the same proportions, except that the catalyst is triethylenediamine in place of DBTDL. The urethane product is again verified by IR scan as above and isolated.

The results of both Examples II and Ila are shown in Table EXAMPLE 111 Hexyl isocyanate is treated with methanol in the presence of presence of DBTDL in 25 ml of tetrahydrofuran in the following proportions: 3.2g methanol 0.3g DBTDL 12.0g hexyl isocyanate When IR scans indicate that the reaction is complete and the expected urethane absorption peaks are present, the urethane is isolated as product.

EXAMPLE Illa The same components as in Example Ill are used in the same proportions, except that the catalyst is triethylenediamine in place of DBTDL. The urethane product is again verified by IR scans as above and isolated.

The results of both Examples III and Illa are shown in Table I.

EXAMPLE IV Hexyl isocyanate is treated with isopropanol in the presence of DBTDL in 25ml of tetrahydrofuran in the following proportions: 6.0g isopropanol 0.3g DBTDL 12.0g hexyl isocyanate When IR scans indicate that the reaction is complete and the expected urethane absorption peaks are present, the urethane product is isolated as product.

EXAMPLE IVa The same components as in Example IV are used in the same proportions, except that the catalyst is triethylenediamine in place of DBTDL. The urethane product is again verified by IR scans as above and isolated.

The results of both Examples IV and IVa are shown in Table I.

EXAMPLE V Hexyl isocyanate is treated with phenol in the presence of DBTDL in 100 ml of tetrahydrofuran in the following proportions: 25.0g phenol 0.05g DBTDL 0.25g hexyl isocyanate When IR scans indicate that the reaction is complete and the expected urethane absorption peaks are present, the urethane product is isolated as product.

EXAMPLE Va The same components as in Example V are used in the same proportions, except that the catalyst is triethylenediamine instead of DBTDL. The urethane product is again verified by IR scans as above and isolated.

The results of both Examples V and Va are shown in Table I.

EXAMPLE VI Hexyl isocyanate is treated with polyethylene glycol in the presence of DBTDL in 25 ml of tetrahydrofuran in the following proportions: 3.8g polyethylene glycol 0.5g DBTDL 2.5g hexyl isocyanate When IR scans indicate that the reaction is complete and the expected urethane absorption peaks are present, the urethane polymer is isolated as product.

EXAMPLE Vla The same components as in Example VI are used in the same proportions, except that the catalyst is triethylene-diamine in place of DBTDL. The urethane polymer is again verified by IR scans as above and isolated.

The results of both Examples VI and Vla are shown in Table EXAMPLE VII Hexyl isocyanate is treated with poly(p-vinyl phenol), obtained from Polyscience, Inc. of Warrington, Pennsylvania, in the presence of DBTDL in 25 ml of tetrahydrofuran in the following proportions: 10.0g poly(p-vinyl phenol) 0.5g DBTDL 2.0g hexyl isocyanate When IR scans indicate that the reaction is complete and the expected urethane absorption peaks are present, the urethane-modified polymer is isolated as product.

EXAMPLE Vlla The same components as in Example VII are used in the same proportions, except that the catalyst is triethylenediamine in place of DBTDL. The urethane-modified polymer is again verified by IR scans as above and isolated.

The results of both Examples VII and Vlla are shown in Table EXAMPLE VIII Hexyl isocyanate is treated with a phenol-formaldehyde resin, Alnovol PN-429 obtained from Hoechst AG of Frankfurt, West Germany, in the presence of DBTDL in 100 ml of tetrahydrofuran in the following proportions: 50. or phenol-formaldehyde resin 0.5g DBTDL 2.5g hexyl isocyanate When IR scans indicate that the reaction is complete and the expected urethane absorption peaks are present, the urethane-modified polymer is isolated as product.

EXAMPLE VIlla The same components as in Example VIII are used in the same proportions, except that the catalyst is triethylenediamine in place of DBTDL. The urethane-modified polymer is again verified by IR scans as above and isolated.

The results of both Examples VIII and VIlla are shown in Table I.

EXAMPLE IX Mondur HC, obtained from Mobay Chemical Company of Pittsburgh, Pennsylvania, an aliphatic/aromatic polyisocyanate copolymer dissolved in ethylene glycol diacetate and xylene, is treated with Alnovol PN-429 in the presence of DBTDL in 50 ml of tetrahydrofuran in the following proportions: 25.0g phenol4ormaldehyde resin 0.05g DBTDL 1 .5g Mondur HC When IR scans indicate that the reaction is complete and the expected urethane absorption peaks are present, the urethane-modified polymer is isolated as product.

EXAMPLE IXa The same components as in Example IX are used in the same proportions, except that the catalyst is triethylenediamine in place of DBTDL. The urethane-modified polymer is again verified by IR scans as above and isolated.

The results of both Examples IX and IXa are shown in Table I.

EXAMPLE X Hexyl isocyanate is treated with a phenol-formaldehyde resin, Alnovol PN-430 obtained from Hoechst AG of Frankfurt, West Germany, in the presence of DBTDL in 25 ml of tetrahydrofuran in the following proportions: 10.0g phenol formaldehyde resin 0.5g DBTDL 5.0g hexyl isocyanate When IR scans indicate that the reaction is complete and the expected urethane absorption peaks are present, the urethane-modified polymer is isolated as product.

EXAMPLE Xa The same components as in Example X are used in the same proportions, except that the catalyst is triethylenediamine in place of DBTDL. The urethane-modified polymer is again verified by IR scans as above and isolated.

The results of both Examples X and Xa are shown in Table I.

EXAMPLE Xl Butyl isocyanate is treated with Alnovol PN-430 in the presence of DBTDL in 25 ml of tetrahydrofuran in the following proportions: 10 .or phenol-formaldehyde resin 0.5g DBTDL 5.0g butyl isocyanate When IR scans indicate that the reaction is complete and the expected urethane absorption peaks are present, the urethane-modified polymer is isolated as product.

EXAMPLE Xla The same components as in Example Xl are used in the same proportions, except that the catalyst is triethylenediamine in place of DBTDL. The urethane-modified polymer is again verified by IR scans as above and isolated.

The results of both Examples XI and Xla are shown in Table I.

EXAMPLE XII Hexyl isocyanate is treated with a resole resin, namely Schenectady SP-134 obtained from Schenectady Chemical Incorporated, S'chenectady, New York, in the presence of DBTDL in 25 ml of tetrahydrofuran in the following proportions: 10.0g resole resin 0.5g DBTDL 5.0g hexyl isocyanate When IR scans indicate that the reaction is complete and the expected urethane absorption peaks are present, the urethane-modified polymer is isolated as product.

EXAMPLE Xlla The same components as in Example XII are used in the same proportions, except that the catalyst is triethylenediamine in place of DBTDL. The urethane-modified polymer is again verified by IR scans as above and isolated.

The results of both Examples XII and Xlla are shown in Table I.

EXAMPLE XIII Hexyl isocyanate is treated with a cresol-formaldehyde resin in the presence of DBTDL in 25 ml of tetrahydrofuran in the following proportions: 10.0g cresol-formaldehyde resin 0.3g DBTDL 5.0g hexyl isocyanate When IR scans indicate that the reaction is complete and the expected urethane absorption peaks are present, the urethane-modified polymer is isolated as product.

EXAMPLE Xlila The same components as in Example XIII are used in the same proportions, except that the catalyst is triethylenediamine in place of DBTDL. The urethane-modified polymer is again verified by IR scans as above and isolated.

The results of both Examples XIII and Xlila are shown in Table I.

EXAMPLE XIV Hexyl isocyanate is treated with a cresol-formaldehyde copolymer in the presence of triethylenediamine in 25 ml of tetrahydrofuran in the following proportions: 10.0g cresol-formaldehyde resin 0.3g triethylenediamine 5.0g hexyl isocyanate When IR scans indicate that the reaction is complete and the expected urethane absorption peaks are present, the urethane-modified polymer is isolated as product.

EXAMPLE XIVa The same components as in Example XIV are used in the same proportions, except that the catalyst is quinuclidine in place of triethylenediamine. The urethane-modified polymer is again verified by IR scans as above and isolated.

The results of both Examples XIV and XIVa are shown in Table I.

EXAMPLE XV Butyl isocyanate is treated with a cresol-formaldehyde copolymer in the presence of DBTDL in 50 ml of tetrahydrofuran in the following proportions: 1 2.0g cresol-formaldehyde copolymer 0.79 DBTDL 10.0g butyl isocyanate When IR scans indicate that the reaction is complete and the expected urethane absorption peaks are present, the urethane-modified polymer is isolated as product.

EXAMPLE XVa The same components as in Example XV are used in the same proportions, except that the catalyst is triethylamine, an aliphatic non-cyclic tertiary amine, in place of DBTDL. The urethanemodified polymer is again verified by IR scans as above and isolated.

The results of both Examples XV and XVa are shown in Table I.

T A B L E I Examples DBTDL triethylenediamine quinuclidine triethylamine II + IIa 0.5 hr. c 7 hr. inc. III + IIIa 0.25 hr. c 2 hr. inc.

IV + IVa 0.25 hr. c 7 hr. inc.

V + Va 1 hr. c 4 hr. c VI + VIa 2 hr. c 7 hr. inc.

VII + VIIa 5 hr. c 7 hr. inc.

VIII + VIIIa 7 hr. inc. 2 hr. c IX + IXa 7 hr. inc. 2 hr. c X + Xa 7 hr. inc. 2 hr. c XI + XIa 7 hr. inc. 2 hr. c XII + XIIa 7 hr. inc. 2 hr. c XIII + XIIIa 7 hr. inc. 2 hr. c XIV + XIVa 1.5 hr. c 0.5 hr. c XV + XVa 5 hr. c 5 hr. inc. indicates reaction runs to completion within indicated time indicates reaction does not run to completion within indicated time, but does run to completion within 24 hours no reaction of components is observed within time indicated As Table I clearly indicates, the catalysis of the urethanation of simple alcohols (methanol, isopropanol, polyethylene glycol) proceeds faster in the presence of DBTDL than in the presence of triethylenediamine. This is also true of the catalysts of the urethanation of other relatively simple hydroxy compounds such as phenol and poly(p-vinyl phenol), as shown in Table I.It is apparent, however, that the catalysis of phenolic resins is significantly more rapid in triethylenediamine and quinuclidine than in DBTDL. This is completely surprising and unexpected in the light of the prior art. Further, Table I also establishes that the catalysts used in the process of this invention must be cyclic tertiary amines since triethylamine, an aliphatic non-cyclic tertiary amine, does not exhibit the increased catalytic activity.

Surprisingly, quinuclidine appears to be a more active catalyst than triethylenediamine in this context. The basicities of the two catalysts are comparable yet statistically one might expect the doubled effective concentration of nitrogen atoms to prevail in the case of the bifunctional molecule, triethylenediamine, over quinuclidine. Apparently bifunctionality on the same molecule is counterproductive in comparison to the mono-functional bicyclic tertiary amine.

Claims (21)

1. A process for the manufacture of a modified phenol-formaldehyde resin, which comprises treating a phenol-formaldehyde resin with an organic isocyanate in the presence of a catalytic quantity of a bicyclic tertiary amine.

2. A process as claimed in claim 1, wherein the phenol in the phenol-formaldehyde resin is phenol itself.

3. A process as claimed in claim 1, wherein the phenol in the phenol-formaldehyde resin is cresol.

4. A process as claimed in any one of claims 1 to 3, wherein the isocyanate is a monoisocyanate.

5. A process as claimed in any one of claims 1 to 3, wherein the isocyanate is an polyisocyanate.

6. A process as claimed in claim 5, wherein the isocyanate is an isocyanate-containing copolymer.

7. A process as claimed in any one of claims 1 to 6, wherein each ring of the amine is 6membered .

8. A process as claimed in any one of claims 1 to 6, wherein the amine is triethylenediamine.

9. A process as claimed in any one of claims 1 to 6, wherein the amine is quinuclidine.

10. A process as claimed in any one of claims 1 to 9, wherein the isocyanate is present in a proportion of 0.1 to 20% by weight, based on the weight of the phenolformaldehyde resin.

11. A process as claimed in any one of claims 1 to 10, wherein the catalyst is present in a proportion of 0.1 to 10% by weight, based on the weight of the phenol-formaldehyde resin.

12. A process as claimed in any one of claims 1 to 11, carried out in a solvent.

13. A process as claimed in claim 12, wherein the solvent is a non-hydroxylic moisture-free solvent.

14. A process as claimed in claim 1, carried out substantially as described in any one of Examples Vllla, IXa, Xa, Xla, Xlla, Xllla, XIV, or XlVa.

15. A urethane-modified phenol-formaldehyde resin, whenever produced by a process as claimed in any one of claims 1 to 14.

16. A varnish, lacquer or binder comprising a resin as claimed in claim 15.

17. A light-sensitive composition comprising a resin as claimed in claim 15 and a photosensitive material.

18. A light-sensitive composition comprising a resin as claimed in claim 15 and an quinone diazide.

19. A lithographic plate having a photosensitive composition comprising a resin as claimed in claim 15 as carrier or binder.

20. A positive-acting lithographic plate having as light-sensitive material a quinone diazide in a resin as claimed in claim 15.

21. Any new or novel feature or combination of features hereinbefore described.