IE40274L - Resinous sulphonated polyisocyanates - Google Patents

Description

40274 This invention relates to resinous sulphonated polyisocyanates. British Patent Specification No. 1,383,184 relates to a process for the production of liquid aromatic poiyisocyanates which contain sulphonic acid and/or sulphonate 5 groups, in which liquid multi-component mixtures of aromatic polyisocyanates are mixed with sulphur trioxide, oleum. sulphuric acid or chloro-sulphonic acid and left to react, % nnd the sulphonation products obtained in this way may be partly or completely neutralised with a basic compound. IO During further development of this process, it has surprisingly been found that, at a higher degree of sulphonation, resinous isocyanate sulphonic acids and their salts are obtained which are brittle, solid products at room temperature and which can in many cases be pulverised. 15 It has, in particular, been found that these brittle solid resinous isocyanates are obtained when the - 2 - 40274 • lu.int i ty of sulphur trioxido used for sulphonation is more than 67. and preferably more than 10.1%. Furthermore, it has been found that the functionality of the isocyanate influences the aggregate state of the sulphonation product. 5 Whereas isocyanates with a functionality of 2.0 to 2.2 generally give rise to liquid isocyanate sulphonic acids, isocy.inatcs which have an average functionality of more than 2.2 very rapidly give rise to highly viscous and finally sol Id, resinous products. In the 'solid isocyanate sulphonic lO acids obtained in this way, the proportion of crystalline products is, contrary to expectations, very low and frequently not even detectable, so that even the solid resinous products arc more closely related in crystallographic respect to the 1iquid products of the process according to British Patent 15 Specification No. 1,383,184, than to true solids.

This invention thus relates to a further development of the process for producing aromatic polyisocyanates which contain sulphonic acid and/or sulphonate groups in accordance with British Patent Specification No. 1,383,184, in which 20 1iquid multi-component mixtures of aromatic polyisocyanates which have a viscosity of SO to 100,000 cP at 25°C and an iso-cyanate-content of 6 to 42 percent by weight are reacted at 50 to 200°C with 6 to 32 percent by weight of sulphur trioxide or an equivalent quantity of oleum and the resulting sulphonation 25 products may be completely or partly neutralised with a basic compound.

This invention also relates to the resinous polyisocyanates obtainable by this process which contain sulphonic acid and/or sulphonate groups. 30 For the process according to the invention liquid aromatic polyisocyanate mixtures are used which have an isocyanate-content of 6 to 4 2 percent by weight, preferably 18 to 35 percent by weight and a viscosity at 25°C - 3 - 40274 / of 50 to 1 do,000 and an average isocyanate functionality of aore than 2.2. The following are exaaplea of such polyisocyanates: 1. All the polyiaocyanate aixtnrea desorlbed as starting aaterlala in British Patent Specification No. 1,383,184 which satisfy the above conditions; 2. liquid aroaatio polyisocyanate aixtures within a viscosity range of 10.000 to 100,000 eP at 25°C which repreaent substantially aixtures of higher hoaologa or analogs of the polyisocyanates described in British Patent Specification No. 1,383,184 phosgenatlon produots of aniline foraaldehyde condensates containing at least 50 peroent by weight of trlfunotlonal and higher fanotlonal polylsooyanates, solutions in such phosgenatlon products of distillation residues obtained froa the distillation of coaaercial tolylene dilsocyanate aixtures, which solutions oontain up to 60 peroent by weight of dlatlllatlon residue. Distillation residues of this kind and the corresponding solutions have been desorlbed, for exaaple, In Geraan Offenlegungschrlften No. 2^35,731 and 2, 123,183. 3. Solutions within a visooslty range of 10,000 to 100,000 oP at 25°C of uretdlone polyisocyanates, triaerlsed polyisocyanates, urethane—, biuret- or allophanate-polylsocyanates in liquid phosgenatlon produots of aniline foraaldehyde condensates.

The sulphonating agent which is preferably used in the process acoordlng to the invention is sulphur trioxide, either as suoh or in the fora of oleua with a sulphur trioxide content of 20 to 70 %.

Sulphonation is carried out as described in British Patent Specification No. 1,383,184, as is the neutralisation which nay be carried out after sulphonation. Sulphonation is 4027 4 preferably carried out by gasifying the reaction alxture with sulphur trioxide at 50 to 200°C, In particular 80 to 180°C» This Is achieved e.g. by passing a streaa of nitrogen through a 65 % oleua and oonductlng the gas alxture 5 into or over the reaction alxture. The reaction with sulphur trioxide Is practically instantaneous. Inert solvents say be Included if Beans are provided for removing then at the end of the reaction.

If the degree of sulphonation is high, e.g. with aore 10 than 15 f of sulphur trioxide, part of the solvent (e.g. 10 to 50 based on the sulphonated isocyanate) oay be left in the product, provided that the product reoalns a resinous solid in spite of its solvent content. The use of solvents has the advantage that the sulphonation of even highly viscous 15 products can be carried out at rooa temperature.

Oleua with a sulphur trloxlde-content of 20 to 70 % aay also be used for sulphonation, particularly if only low degrees of sulphonation of not aore than 12 percent by weight of sulphonic acid groups are desired. The use of oleua has, 20 however, the disadvantage coapared with the use of pure sulphur trioxide,that it causes a reduction in the isocyanate functionality owing to the side reaction between sulphuric acid and Isocyanates. Sulphuric acid and chlorosulphonic acid rrviy also used but ure less preferred for the purpose of this invention. 25 The neutralisation of the Isocyanate sulphonic acids first foraed Is often accompanied by an lnorease In viscosity. It Is only when tertiary amines are used that a fall in viscosity can be observed. Furtheraore, both the hydrophilic character and the reactivity of the products lnorease 30 considerably. In aany cases, this results In a reduction in the stability In storage.

If neutralisation is required, it Is therefore advisable - 5 - 40274 to carry It out only shortly before the produet Is to be used. Furtheraore, it has been found advantageous to carry out only a partial neutralisation, e.g. of 5 to 40 %, based on the theoretical quantity of SO^H-groups (calculated 5 froa the sulphur content). If aalnes or strong alkalis are used for neutralisation, a degree of neutralisation of 5 to 20 £ is preferred. It is only when neutral salts or weak bases which have the charaoter of fillers are used as neutralising agents, such as aagneslua carbonate, calelua 10 carbonate, bariua oarbonate, zinc carbonate, oalolua acetate, oalclua oxalate, aagneslua oxide, sino oxide, iron hydroxide or oeaent that the neutralising agent aay, without risk, be used in excess.

Neutralisation is preferably oarried out by adding the 15 above aentioned solid neutralising" agents, which have the character of a filler, after the produet has been cooled in order to facilitate pulverisation of the produot. If spray pulverisation is 6aployed, the already pulverised produot aay be alxed with neutralising fillers. 20 If lnorganlo neutralising agents are used, care should be taken to ensure that the water liberated in the neutralisation reaction reaets with the isocyanate groups, in particular to fora urea groups. If it is desired to avoid the resulting reduotlon in lsooyanate-content, it is 25 advisable to use tertiary aalnes as neutralising agents, e.g. trlethylaalne or pyridine.

The sulphur content of the products of the process is always lower than the quantity calculated froa the quantlby of sulphur trioxide put into the reaction beoause, In the 30 presence of dlphenylaethane derivatives, part of the sulphur is lost by the evolution of sulphur dioxide. Because of the relatively high teaperature, preferably 80 to 180°C, at which the process according to the invention is carried - 6 - 4027 J out, the products of the process contain, besides sulphonio acid groups, varying proportions of by-products, in particular of the kind formed by the reaction between sulphonic acid groups and Isocyanate groups at elevated temperatures. 5 The products obtained by usfe of the process according to the Invention, however, are invariably soluble or at least dispersible, in aqueous alkalis at 60 to 100°C because of their free sulphonio acid groups or, if the sulphonic acid groups have already been partly or completely neutralised, 10 the products are soluble or at least dispersible in water.

The preferred products according to the invention are characterised by a) a softening point according to DIN 53 460 of at least 35°C (under a load of 1 kp), 15 b) an lsocyanate-content of 3 to 20, preferably 3 to 8, percent by weight and c) a sulphur content of 2.2 to 10, and preferably 2.6 to 6.5,percent by weight.

The sulphur content of the products of the process 20 can be determined by elementary analysis in known manner.

The isocyanate-content can be determined by the conventional method with dlbutylamine. When determining the lsocyanate-oontent, however, it is necessary to take into account the consumption of dlbutylamine by the neutralisation reaction 25 with free sulphonio acid groups, which in turn can be determined quantitatively by potentlometrio titration.

In the process according to the Invention, it is preferred to operate within two restricted ranges because resins or resinous powders with exceptionally advantageous 30 properties are then obtained: 1. Sulphonation of Isocyanate mixtures which have a viaooslty of 50 to 10,000 cP (25°C) with 12 to 32 - 7 - 4 0 2 7 4 percent by weight of sulphur trioxide. 2. Sulphonation of Isocyanate aixtures which have a viscosity of between about 15>000 and 100,000 cP (25°C) with 6 to 20 percent by weight of sulphur 5 trioxide.

As already nentloned above, particularly preferred produots are pulverulent sulphonated polyisooyanates with an lsocyanate-content of 3 to 8 percent by weight and a sulphur content. Introduced by aeans of sulphonatlng agents, 10 of 2.6 to 6.5 percent by weight, and a softening range above 35°C.

Products of this kind are obtained when liquid Isocyanate aixtures which have an average functionality of aore than 2.2, an lsocyanate-content of 18 to 35 percent by weight and a 15 viscosity of 400 te 10,000 cP at 25°C are nixed with 12 to 20 percent by weight of sulphur trioxide or an equivalent quantity of high-percentage oleua with a sulphur trioxide oontent of 20 to 70 $ In such a way that the tenperature at the end of the nixing process is between 80° and 20 180°C, and the brittle-solid resin formed after cooling is pulverised or sprayed hot, the spray mist being obtained in the forn of a powder when cold, the produot being optionally oonpletely or partly neutralised before or after cooling. The terns "sulphonated polyisocyanates" and "aromatic 25 polyisocyanates which contain sulphonic acid groups and/or sulphonate groups" also include of course the equilibrlun aixtures which are formed in known manner by the reaction of sulphonic acid groups with isooyanate groups and which coaprise in particular the adducts which contain mixed 30 anhydride groups and their secondary products. The only essential requlrenent for the purpose of this Invention is that the products should behave as Isocyanate sulphonic - 8 - 40^74 aoids, I.e. they should both enter Into typical isocyanate reactions (reaotion with Zerewltlnoff-actlve secondary aalnes or aloohols, evolution of carbon dioxide on addition of water) and behave like acids (pH below 2 In water, 5 capable of being neutralised with bases). A feature which is of aajor laportance for their practical application and characteristic of thea is the ease with which they can be eaulslfled without eaulsifying agent in alkaline aqueous aedla, e.g. in 1 to 10 % sodlua hydroxide or sodiua sllloate 10 solution at 60 to 100°C.

The solid and preferably pulverulent products obtainable by the process according to the invention are new and versatile in their application. They are readily soluble or dispersible in water or aqueous alkalis even when they 15 are still in the fora of free sulphonic acids but especially in the fora of their salts. Because of their hydrophllic charaoter they are easily hardened by ataospherie aolsture. This hardening reaction is accoapanled by chain-lengthening or crosslinking resulting In the foraation of polyureas. 20 Because of these properties, the products are suitable for use as eaulslflers or wetting agents, for the production of ion exchangers, as hydraulic binders, as thickeners in aqueous systeas, as surface-coating agents and as orossllnklng agents for vinyl polyaers, polyurethanes, 25 polyureas and polyaaides.

As highly sulphonated isocyanates they are alaost ooapletely non-toxlo and the substances obtained when the polyaers foraed froa the products undergo degradation are also non-toxic. - 9 - 40274 Exaaple 1 1000 g of a orude phosgenatlon produet of an aniline foraaldehyde condensate froa which sufficient dlnuelear constituent was distilled off to result in a distillation 5 residue with a visoosity of 400 eP were gasified with sulphur trioxide at 100 to 110°C. 98 g of sulphur trioxide (9*8 % based on the isocyanate) were taken up In 18 hours. The produot was poured out at 140°C and solidified when oold to a brittle resin. The theoretical sulphonio acid 10 group content, calculated froa the sulphur oontent of 3.3%, ;was 8.2%. The resin could be crushed to a powder in a mortar. Exaaple 2 ;A slailar phosgenatlon product which had a viscosity of 2000 was sulphonated with 92 g of sulphur trioxide at 15 100 to 140°C. The highly vlsoous reaotlon alxture solidified to a brittle resin at rooa teaperature. The theoretical sulphonic acid group content calculated froa the sulphur content of 2.6 ^ was 6.5%. ;Exaaple 3 ;20 100 g of a 25 % solution of a distillation residue froa the distillation of coaaerclal tolylene dllsocyanate In the orude phosgenatlon product of an aniline foraaldehyde condensate (visoosity at 25°C: 15 000 cP; isocyanate-content 28 peroent by weight) were gasified with 12 g of 25 sulphur trioxide while the teaperature gradually rose froa ;40°C to 160°C. The highly viscous aass was poured out at 150°C and solidified to fora a springy-hard resin which could be pulverised at rooa teaperature. The sulphonic aold group content was calculated froa the sulphur content 10 of 3.3 $ to be 8.2. Pulverisation was facilitated by oarrylng it out in the presence of 40 g of caloiua carbonate. ;- 10 - ;40274 ;Exaaple k ;The procedure was the saae as in Exaaple 3 but it was carried out with the addition of 200 g of tetraoh-1oroethane and 26 g of sulphur trioxide (26 %). The 5 product was passed through an evaporator screw and ground up. ;Exaaple 5 ;The procedure was the saae as that described in Exaaple 3 but using only 6.5 g (6.5 %) of sulphur trioxide. An 10 aaorphous, hard resin was again obtained in this experiment. ;Exaaple 6 ;When 130 g of sulphur trioxide were used instead of 98 g in Exaaple 1, the teaperature had to be raised to 15 150°C during the sulphonation process. A resin which could very easily be pulverised was then obtained. When on the other hand, only 40 g of sulphur trioxide were added, the resulting resin could not be pulverised. ;Exaaple 7 ;20 The saae prooedure was used as in Exaaple 1 but 125 g of sulphur trioxide were used (12.5 %, based on the Isocyanate). 32 g (0.156 aol * 10 % of the theory) of N,N-dlbutyl aniline were then stirred in dropwlse. This resulted In a slight decrease in viscosity. The product 25 was poured out at 140°C and solidified to a brittle resin when oold. The sulphur content was 3.9 $.

Exaaple 8 The product produced according to Exaaple 1 could be pulverised considerably more easily if, after the addition 30 of sulphur trioxide, 56 g of calciua oxide were stirred into the mixture in a finely powdered form. This was accompanied by an Increase in viscosity. - 11 - 40274 Kxaaple 9 900 g of a crude phosgenatlon produot of an aniline foraaldehyde condensate, froa which dinuolear constituents were distilled off until the distillation residue had a viscosity of 100 cP, and 100 g of tolylene dllsooyanate (isoaeric alxture 65:35) were gasified with sulphur trioxide, first at rooa teaperature and then with gradual heating to 120°C. A total of 150 g of sulphur trioxide was taken up in 10 hours. The product was poured out while still hot and solidified to a brittle, glassy aass when cold. Sulphur content 4.6 %.

Exaaple 10 50 g of the resin obtained in Exaaple 9 were finely powdered with the addition of 10 g of calclua oxide. The alxture was alxed to a paste with 30 g of cyclohex-anone at 150°C and this alxture was then rapidly and vigorously alxed with 40 g of saturated soda solution at 20°C, a thick, allky white liquid eaulsion (V/O-type) being obtained which hardened to a crosslinked, diphasic synthetic resin within 2 ainutes.

Exaaple 11 500 g of a orude phosgenatlon product of an aniline foraaldehyde oondensate froa which the required quantity of dlnuelear constituent had been distilled off to result in a distillation residue with a viscosity of 170 cP were diluted with 250 g of 1,2-dichloroethane. A solution of 72 g of sulphur trioxide in 144 g of dlchloroethane waB added dropwlse at rooa teaperature over a period of 2 hours, the teaperature rising to 37°C. The product was filtered froa alnor quantities (about 5 g) of precipitate and free froa solvent by heating to 60°C in a vaccua. A bard, brittle resin was obtained on cooling. A saaple - 12 - of the resin in a snail quantity of dichloroetbane could easily be eaulsified in a 2£-solution of sodiua hydroxide at 80°C. i A few drops of triethylaalne were added to another 5 saaple of the resin in a saall quantity of dichloroetbane, and the resin could then easily be eaulsified in hot water by shaking.

Exaaple 12 The procedure was the saae as in Exaaple 11 but 10 138 g of sulphur trioxide (27.6 f based on the isocyanate) in 530 g of dichloroetbane were used. The produot was a springy-hard resin at rooa teaperature even when it still contained about 200 g of dichloroetbane.

Exaaple 13 15 A solution of 30 g of sulphur trioxide in 100 g of dichloroetbane was added dropwlse at 60°C to 500 g of a crude phosgenatlon product of an aniline foraaldehyde condensate, froa which the required quantity of dlnuelear constituents had been distilled off to result in a 20 distillation residue with a viscosity of 80,000 oP, and aost of the solvent was then distilled ofrunder vacuus at 90 to 100°C. The product solidified to a hard resin on cooling. A saaple of the resin could be eaulsified in a 2Jl-solution of sodiua hydroxide at 90°C. A solution of 25 the produot in diohloroethane or cyclohexanone was suitable for lapregnatlng or coating concrete. - 13 - 4 0274

Claims (1)

1. CLAIMS: 1. A process for the production of a solid aromatic polyisocyanate which contains sulphonic acid and/or sulphonate groups in which a liquid multi-component mixture of aromatic 5 polyisocyanates which has a viscosity of 50 to 100,000 cP at 25°C and an isocyanate content of 6 to 42 percent by weight is reacted at 50 to 200°C with 6 to 32 percent by weight of sulphur trioxide or an equivalent quantity of oleum. 2. A process as claimed in Claim 1 in which the sul-10 phonated product is completely or partly neutralised with a basic compound. 3. A process as claimed in Claim 1 or Claim 2 in which the aromatic polyisocyanate mixture has an isocyanate content of 18 to 35%. 15 4. A process as claimed in any of Claims 1 to 3 in which the aromatic polyisocyanate mixture has an average isocyanate functionality of more than 2.2. 5. A process as claimed in any of Claims 1 to 4 in which the aromatic isocyanate mixture has a viscosity of from 20 10,000 to 100,000 cP at 25°C. 6. A process as claimed in any of Claims 1 to 5 in which the sulphonation is carried with sulphur trioxide or oleum with a sulphur trioxide content of 20 to 70%. 7. A process as claimed in any of Claims 1 to 6 25 in which the sulphonation is carried out by gasifying the reaction mixture with sulphur trioxide at 50 to 200°C. 8. A process as claimed in Claim 7 in which the reaction mixture is gasified with sulphur trioxide at 80 to 180°C. - 14 - ft 40274 0. A procojw .»h cl.iiim'd in Claim 7 «»r Claim 8 in which .1 stream of nitrogen is passed through a 65% oleum and the gas mixture is conducted into or over the reaction mixture. 5 lO. A process as claimed in any of Claims 1 to 9 in which the sulphonation is carried out in the presence of an inert solvent. 11. A process as claimed in Claim 1 substantially as herein described with reference to any of the Examples. lO 12. An aromatic polyisocyanate which contains sulphonic acid and/or sulphonate groups when prepared by a process as claimcd In any of Claims I to 11. I 1. A polyisocyanate as claimed in Claim 12 substantially as herein described with reference to any of the Examples. F. R. KELLY S CO. AGENTS FOR THE APPLICANTS. - 15 -