Adhesive Compositions Comprising a Substituted Olefin and a Cation Exchange Resin

1335726 10 15 20 25 30 PATENT SPECIFICATION NO DRAWINGS (22) Filed 14 Dec. 1971 (31) Convention Application No. P 21 00 026.0 (21) Application No. 5793 7/71 (32) Filed 2 Jan. 1971 in (33) Germany (DT) (44) Complete Specification published 31 Oct. 1973 (51) International Classification C07C 121 /40 (52) Index at acceptance CZC 658 66X 79X MC BSK 3 200 20Y 220 221 225 ZZY 30Y 326 366 368 656 (11) (54) ADHESIVE PREPARATIONS COMPRISING A SUBSTITUTED OLEFIN AND A CATION EXCHANGE RESIN (71) We, SCHERING AKTIEN- GESELLSCHAFT, a Body Corporate organ- ised according to the laws of Germany, of Berlin and Bergkamen, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particu- larly described in and by the following state- ment:—- The present invention provides a prepara- tion which comprises a substituted olefin of the general formula (I) X / (1) wherein X represents a —CN group or a group of the formula —COOR, Y represents a halogen atom, a —CN group, or a group of the formula —COOR or —SO,R, and R represents an alkyl group having up to 20 carbon atoms, a cycloalkyl group or a phenyl group, and a strongly acidic cation exchange resin. The invention also provide a prepara- tion which comprises a substituted olefin of the general formula (I) X / CH2 = C (I) '/ Y wherein X represents a —-CN group or a group of the formula -——-COOR, Y represents a halogen atom, a —CN group, or a group of the formula —COOR or —SO_,R, and R represents an alkyl group having up to 20 carbon atoms, a cycloalkyl group or a phenyl group, and an amount of a strongly acidic cation exchange resin that is sufiicient to .....__\ stabilize (as hereinbefore defined) the sub- stituted olefin and a process for stabilizing an adhesive which comprises a substituted ole- fin of the general formula (I) given above, which comprises adding to the adhesive, or adding the adhesive to, an amount of a strongly acidic cation exchange resin that is sufficient to stabilize (as hereinafter defined) the substituted olefin. The substituted olefin used in accordance with the invention is said to be “stabilized” by the cation exchange resin if it remains liquid at room temperature (25°C) longer when mixed with the resin than when it is not mixed with the resin. It is known that a small quantity of an acid gas, for example sulphur dioxide and of a radical acceptor, for example hydroquinone, is capable of stabilizing monomeric cyano- acrylic acid esters against polymerisation (United States Patent Specifications Nos. 2,794,788 and 2,765,332). Sulphur-IV-oxide, S0,, has been the mose widely used stabilizer for inhibiting anionic polymerisation of cyan- acrylic acid esters (that is, polymerisation catalysed by bases). The use of sulphur dioxide has, however, a number of grave dis- advantages. Firstly, a concentration of SO, from 0.001 to 0.01% by weight: must be maintained. As the SO‘, concentration increases, the set- ting speed of the cyanoacrylates drops rapidly. When the concentration is low, the cyano- acrylates are not sufliciently stabilized. Because of the gaseous state of the stabilizer and its low concentration, its quantity is very diflicult to adjust and to determine analytically. Secondly, the monomeric cyanoacrylates are generally obtained by the depolymeriza- tion of polycyanoacrylates. In this manufac- turing process it is advantageous to add in the gas phase more of the acid stabilizer gas than is needed for stabilization. After cooling, the excess of S0,, must be removed by time- 1335726 35 40 45 50 55 60 65 70 75 10 15 20 25 30 35 40 45 50 55 2 1,335,726 consuming operations to obtain a product having the required stability equilibrium and setting speed. Continual measuring of the S02 content cannot be avoided. Finally, a polymeric product obtained from monomers stabilized using SO, releases gas (50,) in certain conditions which is often a nuisance and undesirable. To overcome the afore-mentioned disadvan- tages of sulphur dioxide, German Offen- legungsschrift, No. 1,807,895 proposes the use as stabilizer of, for example, propane sultone. According, however, to a leaflet of Shell AG (July, 1968) this stabilizer is strongly ca11cero- genie; the use of a sultone as stabilizer is therefore hazardous and adhesives stabilized with it cannot be used in surgery. This preparation of the present invention does not share the above-mentioned disadvan- tages and risks of preparations containing sul- phur dioxide or a sultone. The substituted olefin used in the process of the invention is preferably an ester of a--cyanoacrvlic acid, which ester has the general formula ( I 1') CN / CI-I, = C Ex CO——OR (H) in which R has the meaning given above. Pre- ferred esters are a--cyanoacrylic acid esters of the general formula (II) in which R represents an alkyl group containing 1 to 5 carbon atoms or the cyclohexyl group. The methyl ester of a--cyanoacrylic acid (R=methyl) is especially advantageous. The monomeric cyanoacrylic acid esters used as adhesives are obtained by the depoly- merisation of poly-cyanoacrylic acid esters which themselves are manufactured in a known manner by condensing formaldehyde and cyanic ester in the presence of a catalyst, for example piperidine. One or more monomeric esters of n:-cvanoacrvlic acid may be used in the preparation of the invention. The ion exchange resins used according to this invention as stabilizers for the adhesives are inexpensive commercial products. In general. they are condensates and polymers insoluble in water and many other chemical substances, containing groups capable of exchanging ions. Preferred strongly acidic cation exchangers are cross-linked polystyrene, phenol resin or vinyl resin, all of which con- tain sulphonic acid groups (see Ullmanns Enzyklooaedie der technischen Chemie, volume 8 [1957] page 816). The great superiority of the stabilizers according to this invention can be seen in the properties and handling possibilities men- tioned below. The cation exchange resins used according to this invention as stabilizers for adhesives are solid substances and may be added to the monomers in a simple manner. There is no need for time—consuming opera- tions such as those required to remove any excess of sulphur dioxide, and involved analytical methods. When it is to be used, the adhesive can be simply decanted or siphoned oft’ the stabilizer. The setting speed of the substituted ole- fins, for example the cyanoacrylates, is, when the ion exchange resin has been removed, in no way impaired by stabilization in accord- ance with this invention. As the ion exchange resins are insoluble in the substituted olefins, the adhesives stabilized according to this invention have the same setting speed as a completely unstabilized product. The setting speed is considerably greater than that of cyanoacrylates that contain a stabilizer in a dissolved form. Thus it is very simple to satisfy the user’s demand for a cyanoacrylate adhesive which sets very rapidly. There is no physiological risk involved in cyanoacrylates stored over a cation exchange resin because they can be used in the pure form without any additive. They could well, therefore, be very valuable for cementing work in surgery. The invention also provides a process for sticking a first surface of a substrate to a second surface of the same or a different substrate which comprises removing the cation exchange resin from a preparation according to the invention, applying the substituted ole- fin to one or both of the surfaces, placing the surfaces together with the substituted olefin sandwiched between them, and curing the sub- stituted olefin at room temperature or, if desired, at an elevated temperature and an assembly so made. In the manufacture of preparations of the invention, the cation exchange resins may be dried at room temperature or. preferably, at an elevated temperature which is below the maximum temperature indicated by the manu- facturer, and added to the cyanoacrylate or, if desired, they may be so added without first having been dried. When the mono- meric ester has been manufactured in the manner described above with distillation of the monomer the cation exchange resin may be introduced directly into the container in which the condensed, monomeric ester is col- lected. In this way the ester is stabilized immedi. tely and no polymerization is possible. To make manipulation easier and to prolong the potlife of substituted olefins (for example cyanoacrvlates) in partly emptied storage con- tainers, the ion exchange resin may be addi- tionally deposited in the spout or closure of the container. The amount of ion exchange resin added to the substituted olefin is not critical and may be varied within wide limits. An addi- tion of 5?.) by weight will be found quite 60 65 75 80 85 90 95 100 105 110 115 120 10 15 20 30 35 40 45 50 55 60 1,335,726 adequate in most cases. In many cases even a smaller quantity will sutfice to bring about the desired potlife of the adhesive. To summarize, it may be said that the stabilizers used according to this invention are much more reliable, suitable for many more uses, simpler and less hazardous than the hitherto known products for stabilizing cyanoacrylates. The substituted olefins stabil- ized according to this invention are more stable and cure more rapidly than the hitherto known mixed cyanoacrylate stabilizers. Though it is not absolutely necessary, it may be desirable to incorporate in the pre- paration of the invention or in the substituted olefin or cation exchange resin used in making the preparation, an inhibitor for free radical polymerisation, since the cyanoacrylates are also capable of undergoing free radical poly- merisation. Such inhibitors are, for example, quinone, hydroquinone, and para—methoxy- phenol. These inhibitors may be added in a concentration ranging from about 0.001 to 1 % calculated on the weight of the substituted olefin. It is, of course, also possible to modify the adhesives with a view to improving cer- tain properties. For example, their viscosity may be increased by the addition of a thicken- ing agent. Possible modifications are described in the literature. The following Examples illustrate the inven- tion: Example 1 100 Grams of u--cyanoacrylic acid methyl ester (prepared by depolymerisation of poly- cyanoacrylic acid methyl ester) containing 0.0-1 % by weight of hydroquinone were mixed with 5 grams of dried “Ion exchange resin I” (Messrs. Merck, Darrnstadt). The liquid incorporating the ion exchange resin is shown in the following tests to be an efficient, stabil- ized adhesive: (a) To test the setting speed a drop of the adhesive is put on the cut end of a rubber section (Nitril rubber). The cut end is then brought into contact with a second cut end and the two faces are pressed together for about 3 seconds after which time the two piece of rubber are firmly cemented together. (b): To test the stability of the adhesive over a long period of time a specimen of the stabilized product was kept in an oven heated at 55°C. In this test the adhesive stabilized according to this invention was, even after 40 days’ storage, a clear liquid and in the setting speed test described above it produced bonds which rapidly became firm. Comparative test When a specimen of cyanoacrylic ester from the same charge as that used in Example 1 was kept at 55°C without addition of ion exchange resin its stability was only a few hours and at room temperature it had a stability of 3 days. Example 2 In the experiment described in Example 1 the as-cyanoacrylic acid methyl ester was replaced wholly or partially by a C2- to C1,- alkyl, -phenyl or -cyclohexyl ester of cyano- acrylic acid or by a mixture of such esters. On the whole, the results obtained were simi- lar to those obtained in Example 1; the adhe- sives were stable at room temperature for at least 3 months and, on rubber, metal and many other surfaces, produced bonds which rapidly become firm. Example 3 The “Ion exchange resin I” (Merck) used in Example 1 was replaced by other ion exchange resins, for example “Permutite RS” (Permutit AG, Berlin-Duisburg) and “Dowex 50 WX 2” (Dow Chemical Comp., Midland, Mich., U.S.A.) “Permutite” and “Dowex” are Trade Marks. The results obtained were sub- stantially similar to those described in Example 1: the adhesives were stable over long periods of time both at room temperature and at 55°C and, on rubber, metal and many other materials, gave bonds which rapidly became firm. WHAT WE CLAIM IS:—— 1. A preparation which comprises a sub- stituted olefin of the general formula (I) (1) wherein X represents a —-CN group or a group of the formula ——-COOR, Y represents a halogen atom, a —-CN group, or a group of the formula ——COOR or ——S0,R, and R represents an alkyl group having up to 20 carbon atoms, a cycloalkyl group or a phenyl group, and a strongly acidic cation exchange resin. 2. A preparation which comprises a sub- stituted olefin of the general formula (I) X / CI-I,=C (I) .\ Y where X represents a —CN group or a group of the formula —-COOR, Y represents a halogen atom, 3. —CN group, or a group of the formula —-COOR or —SO,R, and R represents an alkyl group having up to 20 carbon atoms, a cycloalkyl group or a phenyl group, and an amount of a strongly acidic 65 70 75 80 85 90 95 100 105 110 10 15 20 30 35 410 1,335,726 cation exchange resin that is sufiicient to stabilize (as hereinbefore defined) the sub- stituted olefin. 3. A preparation as claimed in claim 1 or claim 2, wherein the substituted olefin is an ester of a--cyanoacrylic acid, which ester has the general formula (II) CN / CH._.=C .\ CO-OR (H) in which R has the meaning given in claim 2. 4. A preparation as claimed in claim 3, wherein, in general formula (II), R represents an alkyl group having up to 5 carbon atoms or a cyclohexyl group. 5. A preparation as claimed in claim 3 or claim 4, wherein the substituted olefin is the methyl ester of c.»-cyanoacrylic acid. 6. A preparation as claimed in any one of claims 1 to 5, wherein the strongly acidic cation exchange resin comprises crosslinked polystyrene containing sulphonic acid groups, a phenol resin containing sulphonic acid groups, or a vinyl resin containing sulphonic acid groups. 7. A preparation as claimed in any one of claims 1 to 6, which contains up to 50.1. by weight, based on the weight of the substituted olefin, of the strongly acidic cation exchange resin. 8. A preparation as claimed in any one of claims 1 to 7, which also comprises a free radical polymerisation inhibitor. 9. A preparation as claimed in claim 8, wherein the inhibitor is quinone, hydroquinone or p-methoxyphenol. 10. A preparation as claimed in claim 8 or claim 9, wherein the concentration of inhibitor is from 0.001 to 1",’, by weight, calculated on the weight of the substituted olefin. 11. A preparation as claimed in claim 2 and described in any one of the Examples herein. 12. A process for stabilizing an adhesive which comprises a substituted olefin of the general formula (1) given in claim 1, which comprises adding to the adhesive, or adding the adhesive to, an amount of a strongly acidic cation exchange resin that is suflicient to stabilize, as hereinbefore defined) the sub- stituted olefin. 13. A process as claimed in claim 12, wherein the substituted olefin is as specified in any one of claims 3 to 5. 14. A process as claimed in claim 12 or claim 13, wherein the resin is as specified in claim 6. 15. A process as claimed in any one of claims 12 to 14, wherein up to 5% by weight of resin, based on the weight of the sub- stituted olefin, is used. 16. A process as claimed in any one of claims 12 to 15, wherein a free radical poly- merisation inhibitor is mixed with either the resin or the adhesive, or the mixture obtained from them. 17. An adhesive preparation whenever obtained by a process as claimed in any one of claims 12 to 16. 18. A process for sticking a first surface of substrate to a second surface of the same or a difl°erent substrate which comprises remov- ing the cation exchange resin from a pre- paration as claimed in any one of claims 1 to 11 and 17, applying the substituted olefin to one or both of the surfaces, placing the surfaces together with the substituted olefin sandwiched between them, and curing the substituted olefin at room temperature or, if desired, at an elevated temperature. 19. An assembly whenever produced by a process as claimed in claim 18. ABEL & IMRAY, Chartered Patent Agents, Northumberland House, 303-306. High Holborn, London, W.C.1. Pt'inter_l for Her Maiesty’s Statiorteigv Office. by the ('nurier Press. Leamington Spa. I973. Pttblislsed by The Patent Ofiice. Soutlianipton Buildings, London. \\'(,'i.‘A IAY, from which copies may he obtained. 4 50 55 60 65 70 75 80 85 "\