GB2225577A - Fluoroalkyl 2-cyanoacrylate and curable compositions - Google Patents

Description

n - 1 -77 2 225b 1 - 1 Fluoroalkyl 2-eyanoacrylate and curable composition

The present invention relates to a novel 2cyanoacrylate compound which is curable at ambient temperature and excellent in water resistance and moisture resistance. The present compound can be utilized in a wide range of industrial fields. For example, the present compound can be used as an adhesive, a coating agent, a potting agent and the like. Also, the polymer of the present compound can be used as positive type resists and optical-path forming clad materials.

lkyl 2-cyanoacrylates have been conventionally used as a material for oneliquid type instantaneous adhesives which polymerize and cure at ambient temperature in the presence of a very small amount of moisture on an adherend. Such adhesives have been widely used for bonding metals, plastics, rubbers, woods, ceramics, living tissues and the like.

However, a disadvantage of conventional instantaneous adhesives comprising alkyl 2-cyanoacrylates is that when those adhesives are brought into contact with water for a long period after curing, their bonding strength is deteriorated.

Various attempts have been made to improve alkyl 2-cyanoacrylate adhesives in water resistance and moisture resistance. One of them is to introduce fluorine into the alkyl group of an alkyl 2-cyanoacrylate. This technique is disclosed, for example, in United States Patents Nos. 3,639,361 and 3,540,126. The former discloses an alkyl 2cyanoacrylate the alkyl group of which is simply fluorinated. The latter discloses a 2-cyanoacrylate the carboxyl group of which is bonded via its ether linkage with a fluoroalkyl group.

- - 2 - However, a problem of the former compound is that its raw material, namely, cyanoacetate cannot be obtained by ordinary esterification from an acid and an alcohol,'and thus has to be synthesized by a process from an acid chloride and an alcohol at low production. Its further problem is that the step in which 2-eyanoacrylate is synthesized from cyanoacetate is also low in production so that it cannot be utilized in an industrial scale.

The latter compound can be synthesized by an ordinary process at relatively high production. However, it is still insufficient in water resistance and moisture resistance.

It is an object of the present invention to provide a novel fluoroalkyl 2eyanoacrylate which is useful as a material for water- and humidresistant adhesives, coating agents and the like.

As a result of intensive researches in an attempt to solve the above-mentioned problems, the present inventors have found a novel fluoroalkyl 2-eyanoacrylate.

The present invention provides a fluoroalkyl 2- cyanoacrylate wherein the fluoroalkyl group contains 3 to 12 carbon atoms and further characterized in that the number 1 and number 2 carbon atoms of the fluoroalkyl group are fluorine free.

The present invention also provides a curable composition which comprises the above-mentioned fluoroalkyl 2-cyanoacrylate and another 2-eyanoacrylate.

The fluoroalkyl 2-eyanoacrylate of the present invention is one the fluoroalkyl group of which contains 312 carbon atoms. In the fluoroalkyl group, neither the -.3 - 1 darbon atom at 1. position nor the carbon atom at 2-position should be fluorinated. In other words, the fluoroalkyl group has to be fluorinated at a carbon atom at 3-12 positions. In order to solve the above-mentioned problems 5 better, it is preferred that the fluoroalkyl group is an alkyl group in which 30 % or more of the hydrogen atoms attached to the carbon atoms at 3-12 positions are substituted with fluorine atoms. It is more preferred that the fluoroalkyl group is one in which 100 % of the hydrogen atoms attached to the carbon atoms at 3-12 positions are substituted with fluorine atoms.

Examples of the fluoroalkyl 2-cyanoacrylates of the present invention are 3,3,3-trifluoropropyl 2- cyanoacrylate, 3,3,4,4,4-pentafluorobutyl 2-cyanoacrylate, 3,3,4,4,5,5,5heptafluoropentyl 2cyanoacrylate, 3,3,4,4,5,5,6,6,6- nonafluorohexyl 2-cyanoacrylate, 3,3,4,4,5,5,6,6,7,7,8,8,8- tridecafluorooetyl 2cyanoacrylate, 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,1020 heptadecafluorodecyl 2-cyanoacrylate, 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, 11,11,12,12,12eicosafluorododecyl 2-cyanoacrylate, 2trifluoromethylpropyl 2-cyanoacrylate, 2-methyl-3,3,4,4,4 pentafluorobutyl 2-cyanoacrylate, 2methyl-3,3,4,4,5,5,5heptafluoropentyl 2-cyanoacrylate, 2-methyl3,3,4,4,5, 5,6,6,6-nonafluorohexyl 2-eyanoacrylate, 2methyl-3,3,4,4,5,5,6,6,7,7,8,8, 8-tridecafluorooetyl 2cyanoacrylate, 2-methyl3,3,4,4,5,5,6,6,7,7,8,8,9,9, 10,10,10-heptadecafluorodecyl 2-cyanoacrylate, and 2-methyl3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12, 12,12heneicosafluorododecyl 2-eyanoacrylate.

The fluoroalkyl 2-eyanoacrylate of the present invention can be synthesized at a good yield in the same way as has been conventionally used for production of 1 ordinary alkyl 2-cyanoacrylates.

For example, flubroalkyl cyanoacetate, which is a raw material of the present fluoroalkyl 2-eyanoacrylate, is 5 synthesized from corresponding fluoroalkyl alcohol and cyanoacetic acid by ordinary esterification reaction in the presence of acid catalyst, or from corresponding fluoroalkyl alcohol and ethyl cyanoacetate by interesterification reaction in the presence of acid 10. catalyst. Then, after neutralization of residual acid catalyst and cyanoacetic acid followed by distillation, pure fluoroalkyl cyanoacetate is obtained. Next, fluoroalkyl cyanoacetate is condensed with paraformaldehyde in a solvent such as toluene and trichloroethylene in the presence of base catalyst such as piperidine. Then, after removal of low boiling point components such as water and solvent under atmospheric or reduced pressure, depolymerization is conducted at high temperature under reduced pressure by use of a non-volatile acid such as phosphorus pentoxide as a catalyst, to give fluoroalkyl 2cyanoacrylate. Further, purity of fluoroalkyl 2cyanoacrylate thus obtained may be increased to 99 % or wore by distillation.

While the fluoroalkyl 2-eyanoacrylate thus obtained polymerizes and cures in the presence of a very small amount of moisture at ambient temperature like the conventional alkyl 2-eyanoacrylate, the former is quite superior in water resistance and moisture resistance to the latter, when hardened.

Therefore, the fluoroalkyl 2-cyanoacrylate of the present invention solves the above-mentioned problems, and thus can be quite effectively used for an excellent material of one-liquid type instantaneous adhesives and coating agents.

-.5 - As stated above, the fluoroalkyl 2-cyanoacrylate of the present invention is a compound which anionicpolymerizes in the presence of a very small amount of moisture or Lewis base such as pyridine on a solid surface like conventional alkyl 2-cyanoacrylates. Therefore, when the present fluoroalkyl 2-cyanoacrylate refined by distillation is preserved, it is preferable that a small amount of a suitable anionic polymerization inhibitor is added thereto. The anionic polymerization inhibitor includes sulfur dioxide, sulfonic acids and boron trifluoride. Addition amount of the anionic polymerization inhibitor may be varied depending upon the type thereof, but is usually 1-10000 ppm.

When the present fluoroalkyl 2-cyanoacrylate is used for an adhesive or coating agent, radical polymerization inhibitor, thickening agent, cure accelerating agent, plasticizer, dye or the like may, be added thereto in combination with anionic polymerization inhibitor. The radical polymerization inhibitor includes hydroquinone, hydroquinone monomethyl ether, catechol, pyrogallol and the like. Addition amount of the radical polymerization inhibitor is usually 1- 10000 ppm. The thickening agent includes polymethylmethacrylate, cellulose acetate and the like. The cure accelerating agent includes polyethylene glycol and its derivatives, crown ethers and the like.

Furthermore, the present fluoroalkyl 2- cyanoacrylate may be combined with at least one of the conventionally used 2-cyanoacrylates, for example, a 2cyanoacrylate of the class conventionally employed in cyanoacrylate adhesives, in order to the provide an adhesive or coating agent which maintains the advantages of both 2-cyanoacrylates. Examples of the conventional 2cyanoacrylates which can be combined therewith are alkyl 2 1 eyanoacrylates such as methyl 2-cyanoacrylate, ethyl 2cyanoacrylate, propyl 2-eyanoacrylate, isopropyl 2cyanoacrylate, butyl 2-cyanoacrylate, isobutyl 2cyanoacrylate and sec-butyl 2-cyanoacrylate, cycloalkyl 2cyanoacrylates such as cyclopentyl 2-eyanoacrylate, cyclohexyl 2cyanoacrylate and cycloheptyl 2-cyanoacrylate, alkenyl 2-cyanoacrylates such as ally 2-eyanoacrylate and methacryl 2-eyanoacrylate, and propargyl 2cyanoacrylate, methoxyethyl 2-cyanoacrylate, ethoxyethyl 2-cyanoacrylate, and chloroethyl 2cyanoacrylate. These conventional 2cyanoacrylates preferably constitute up to 98 % by weight, most preferably up to 90 % by weight of the total of the conventional 2-cyanoacrylates and the present fluoroalkyl 2-cyanoacrylate.

The only difference in chemical structure between the present fluoroalkyl 2-eyanoacrylate and the conventional 2-eyanoacrylate of United States Patents No. 3,639,361 which has a simply fluorinated alkyl group, is that the fluoroalkyl group of the former is not fluorinated at a carbon atom at 1- or 2- position. In spite of this slight difference, it was unexpected that the present fluoroalkyl 2-cyanoacrylate could be synthesized at a high yield in the same manner as ordinary alkyl 2- cyanoacrylates while the mechanism of this synthesis has been unknown.

Furthermore, whilst the fluoroalkyl 2cyanoacrylate of the present invention polymerizes and cures in the presence of a very small amount of moisture at ambient temperature like conventionally employed alkyl 2 cyanoacrylates, it provides a hardened body which Is excellent in water resistance and moisture resistance unlike the conventional alkyl 2-cyanoacrylates.

That is why the present fluoroalkyl 2 cyanoacrylate solves the above-mentioned problems and thus 7 1 can effectively be used as a material for one-liquid type instantaneous adhesives or coating agents.

Hereinafter, the present invention will be set forth in more detail by way of the following non-limitative examples.

Example 1

Synthesis of 3,3,4,4,5,5,6,6,6nonafluorohexyl 2-cyanoacrylate in a three-neck round bottom flask equipped with astirrer, a thermometer, a Dean-Stark water separator and a dropping funnel, were put 19.6 grams of paraformaldehyde with a purity of 92 %, 0.18 gram of piperidine and 60 milliliters of toluene. The mixture was heated to about 80 OC while being stirred. Under the same temperature, 198.6 grams of 3,3,4,4,5,5,6,6,6nonafluorohexyl cyanoacetate was added through the dropping funnel to the mixture for 60 minutes. After the mixture was further heated for eight hours under stirring to azeotropically remove water produced, it turned to a slightly viscous reddish brown liquid. After solvent was removed under atmospheric pressure, 3.6 grams of phosphorus pentoxide and 1.8 gram of hydroquinone were added thereto, and the resultant mixture was thoroughly mixed together. Solvent was removed under reduced pressure, and the mixture was then heated and depolymerized at 160 - 200 OC under a reduced pressure of 4 mmHg to give 129 grams of fractions; b.p.:90 - 99 OC/4 mmHg. Then, the fractions were distillated in the presence of a small amount of phosphorus pentoxide and hydroquinone to give 94 grams of refined monomer; b.p.:94 - 98 OC/4 mmHg. Figures I-A shows 1H-NNIR spectrum of the obtained 31- refined monomer, and Figure I-B is a 16 times magnification of a part of Figure 1-A. Figure 2 shows infrared 8 - 1 absorption spectrum of the obtained refined monomer.

1H-MR spectrum (internal standard acetone in acetone - d6) 67.12 ppm (s, 1H) 66.92 ppm (s, 1H) 64.66 ppm (t, J=6.0 Hz, 2M 62.51 - 3. 52 (m, 2H) Infrared absorption spectrum 1620 cm-1 (>C=CH2) 1760 cml (>C=O) 2260 em-1 (-CEN) To each the refined monomer and a mixture of the refined monomer and ethyl 2-cyanoacrylate in a ratio of 90/10 (weight/weight), were added 30 ppm of sulfur dioxide and 200 ppm of hydroquinone to obtain adhesive compositions. In accordance with JIS-K-6861, set times of the former and latter compositions for hard vinyl chloride were respectively determined to be 30 and 10 seconds. Further, tensile adhesion strengths of the former and latter compositions for 18-8 stainless steel were respectively determined to be 240 kgf/cm2 and 290 kgf/cm2.

Example 2

Synthesis of 3,3,4,4,5,5,6,6,7,7,8,8,8tridecafluorooctyl 2cyanoacrylate In a three-neck round bottom flask equipped with stirrer, a thermometer, a Dean-Stark water separator and dropping funnel, were put 15.1 grams of paraformaldehyde with a purity of 92 %, 0.14 gram of piperidine and 100 milliliters of toluene. And, the mixture was heated to about 80 OC while being stirred. Under the same 1 - 9 temperature, 200 grams of 3,3,4,4,5,5,6,6,7,7,8,8,8tridecafluorooctyl cyanoacetate was added through the dropping funnel to the mixture for 60 minutes. After the mixture was further heated for 12 hours under stirring to azeotropically remove water produced, it turned to a viscous reddish brown liquid. After solvent was removed under atmospheric pressure, 2.8 grams of phosphorus pentoxide and 1.4 gram of hydroquinone were added thereto, and the resultant mixture was thoroughly mixed together.

Solvent was removed under reduced pressure, and the mixture was then heated and depolymerized at 170 - 200 OC under a reduced pressure of 4 mmHg to give 127 grams of fractions; b.p.:93 - 112 OC/4 mmHg. Then, the fractions were -distillated in the presence of a small amount of phosphorus pentoxide and hydroquinone to give 92 grams of refined monomer; b.p.:96 - 100 OC/4 mmHg, m.p.:35.0 - 35.7 OC. Figures 3 and 4 respectively show 1H-NMR spectrum and infrared absorption spectrum of the refined monomer.

'H-NMR spectrum (internal standard tetramethylsilane in CF3COOH,) 67.30 ppm (s, 1H) 66.91 ppm (s, 111) 4.73 ppm (t, J=6.0 Hz, 2H) 62.38 - 2.97 (m, 2H) Infrared absorption spectrum 1620 em-1 (>C=CH2) 1770 cm-1 (>C=O) 2260 cm-1 (CEN) To a mixture of the refined monomer and ethyl 2- cyanoacrylate in a ratio of 50/50 (weight/weight), were added 30 ppm of sulfur dioxide and 200 ppm of hydroquinone.

In accordance with JIS-K-6861, set time of the mixture for hard vinyl chloride was determined to be 10 seconds.

1 Further, tensile adhesion strength of the mixture for 188 stainless steel was determined to be 316 kgf/cm2.

Example 3

Synthesis of 3,3,4,4,5,5,6,6,7,7,8,8,9,9, 10.10.10-heptadecafluorodecyl 2eyanoacrylate In a three-neck round bottom flask equipped with a stirrer, a thermometer, a Dean-Stark water separator and a dropping funnel, were put 12.1 grams of paraformaldehyde with a purity of 92 %, 0. 11 gram of piperidine and 100 milliliters of toluene. And, the mixture was heated to about 80 OC while being stirred. Under the same temperature, a solution of 200 grams of 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, 10-heptadecafluorodecy1 cyanoacetate in 100 milliliters of toluene was added through the dropping funnel to the mixture for 60 minutes. After the mixture was further heated under stirring for 12 hours to azeotropically remove water produced, it turned to a liquid containing reddish brown solid. After the solution was cooled to room temperature and the reddish brown solid was picked up and vacuum-dried, 2. 26 grams of phosphorus pentoxide and 1.13 gram of hydroquinone were added to and mixed thoroughly with the reddish brown solid. Then, the mixture was heated and depolymerized at 180 - 200 OC under a reduced pressure of 4 mmHg to give 110 grams of fractions; b.p.:100 - 112 OC/4 mmHg. Then, the fractions were distillated in the presence of a small amount of phosphorus pentoxide and hydroquinone to give 82 grams of refined monomer; b.p.:110 - 115 OC/5 mmHg, m.p.:43.9 45.2 OC. Figures 5 and 6 respectively show 1H-NMR spectrum and infrared absorption spectrum of the obtained refined monomer.

1 1. 1 - 1 -'H-MR spectrum (internal standard tetramethylsilane in CF3COOH,) 67.30 ppm (s, 1H) 66.92 ppm (s, 1H) 64.73 ppm (t, J=6.0 Hz, 2H) 62.36 - 3.02 (m, 2H) Infrared absorption spectrum 1630 cm-1 (>C=CH2) 1760 cm-1 (>C=O) 2270 cm-1 (-C=N) To a mixture of the refined monomer and ethyl 2cyanoacrylate in a ratio of 50/50 (weight/weight), were added 30 ppm of sulfur dioxide and 200 ppm of hydroquinone. In accordance with JIS-K-6861, set time of the mixture for hard vinyl chloride was determined to be 10 seconds. Further, tensile adhesion strength of the mixture for 18-8 stainless steel was determined to be 280 kgf/cm2.

Example 4

By use of the fluoroalkyl 2-cyanoacrylate refined monomers obtained in Examples 1, 2 and 3 and their compositions with ethyl 2-cyanoacrylate as well as ethyl 2- cyanoacrylate alone as adhesives, 18-8 stainless steels were bonded together to obtain specimens. Tensile adhesive strength was determined after the specimens were immersed in hot water at 50 OC for 10 days. The results are shown in Table.

Further, the same adhesives were each applied in 10 microns thickness to each 18-8 stainless steel plate and polymerized under N,N-dimethyl-ptoluidine atmosphere. Then, contact angles of water to the resultant coatings at 25 OC were determined. Also, adhesion of the coatings to the plates was evaluated with cross cut test initially and 1 af:ter the coatings were immersedIn hot water at 50 OC for 10 days cross cut test. The results are also shown in Table.

Further, the same adhesives were each applied to each glass substrate treated with N,N-dimethyl-p-toluidine. Then, index of refraction each of the resultant polymer films at 20 OC was determined. The results are also shown in Table.

1 Table 1 (Performances of Adhesives used.in Example 4) -T- I I i Tensile adhesive I Contact IComposittonsl Set time I strength (kgf/cm2 I angle I of I I I After 10 days'l I monomers J(hard PVC)l I hot water I I (degree) Unitial 1 1 1Initial 1 immersion Cross cut test 1 Index of 1 Irefractloni 1 After 10 days'I 1 hot water 1 n20 1 i Immersion 1 D i i i i i 1 A 100 1 20 see. 1 240 1 220 1 97 1 100 1 100 1 1.3 902 1 i i i -1 - -- -F-- -- --i.1 [ A 90 1 10 see. 1 290 1 260 1 99 1 100 i 100 1 1-4357 11 1 E 10 1 1 1 1 1 1 1 1 W 1 B 50 1 10 see. 1 316 1 280 1 95 1 100 1 100 1 1.4312. 1.

1 E 50 1 1 1 1 1 1 1 1 c 50 1 1.0 see. 1 280 1 250 1 92 1 1.00 1 100 1 1.4331.1 1 E 50 1 1 1 1 1 1 1 i i i j i i i i 1 E 100 1 5 see. 1 350 1 150 1 75 j 1.00 1 0 1 1.4842 1 Notes: Monomer A Monomer B Momoner C Momoner E 3,3,4,4,5,5,6,6,6-nonafluorohexy1 2-eyanoacrylate 3,3,4,4,5,5,6,6,7,7,8,8, 8-trldecafluorooety1 2-eyanoacrylate 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,1.0, 10-heptadecafluorodecyl 2-eyanoacrylate ethyl 2-cyanoacrylate 14 - The fluoroalkyl 2-eyanoacrylate of the present invention can provide an instantaneous adhesive, a coating agent and a potting agent which are curable at ambient temperature and excellent in water resistance, and can be widely used even in a field where conventional 2cyanoacrylate instantaneous adhesives could not be used.

The polymer of the present fluoroalkyl 2cyanoacrylate is low in index of refraction owing to the effect of fluorine atoms contained therein, and thus can be used as optical-path forming clad materials.

Further, the polymer of the present fluoroalkyl 2-eyanoacrylate can be used as positive resists which ar sensitive to electron beam and X-ray.

is Accordingly, the present invention is consider to produce much effect on a wide range of industries.

ed 0

Claims (13)

1. A fluoroalkyl 2-cyanoacrylate wherein the fluoroalkyl group contains 3-12 carbon atoms and further characterised in that the number 1 and number 2 atoms of the fluoroalkyl group are fluorine free.
2. 2. A fluoroalkyl 2-cyanoacrylate according to Claim 1, wherein said fluoralkyl group is an alkyl group in which 100% of the hydrogen atoms attached to the carbon atoms of 3-12 positions are substituted with fluorine atoms.
3. 3. A curable composition which comprises a fluoroalkyl 2-cyanoacrylate as defined in Claim 1 and another 2-cyanoacrylate.
4. 4. The following compounds either individually or in admixture with one another or in admixture with another 2-cyanoacrylate:

   3,3,3-trifluoropropyl 2-cyanoacrylate; 1 - 16..--- 3, 3,4,4,4-pentafluorobutyl 2-cyanoacrylate; k 3, 3,4,4,5,5,5-heptafluoropentyl 2-cyanoacrylate; 3,3,4,4,5,5,6,6,6-nonafluorohexyl 2-cyanoacrylate; 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl 2-cyano- acrylate; 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluoro- decyl 2-cyanoacrylate; 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-eico safluorododecyl 2-cyanoacrylate; is 2-trifluoromethylpropyl 2-cyanoacrylate; 2-methyl-3,3,4,4,4-pentafluorobutyl 2-cyanoacrylate; 2-methyl-3,3,4,4,5,5,5-heptafluoropentyl 2-cyanoacry- late; 2-methyl-3,3,4,4,5,5,6,6,6-nonafluorohexyl 2-cyanoac- rylate; 17 2-methyl-3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl 2-cyanoacrylate; 2-methyl-3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl 2cyanoacrylate; and 2-methyl-3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12, 12,12- heneicosafluorododecyl 2-cyanoacrylate.
5. 5. A method for making a fluoroalkyl 2-cyanoacrylate wherein the fluoroalkyl group contains 312 carbon atoms and the number 1 and number 2 carbon atoms of the fluoroalkyl group are fluorine free, saidmethod comprising; esterifying a fluoroalkyl alcohol in which the fluoroalkyl group contains 3-12 carbon atoms and the number 1 and 2 atoms of the fluoralkyl group are fluorine free with cyanoacetic acid to form a fluoroalkyl cyanoacetate; condensing the fluoroalkyl cyanoacetate with paraformaldehyde and depolymerising the resulting product to give the fluoroalkyl 2- cyanoacrylate.
6. 6. Amethod for making a fluoroalkyl 2-cyanoacry- 18 late according to Claim 2 substantially as described in Example 1, 2 or 3.
7. 7. A polymer containing recurring units derived from a fluoroalkyl 2cyanoacrylate wherein the fluoroalkyl group contains 3-12 carbon atoms and the number 1 and number 2 carbon atoms of the fluoroalkyl group are fluorine free.
8. 8. A method for forming a water resistant coating on an article which comprises applying to the article a curable composition containing a fluoroalkyl 2cyanoacrylate as claimed in Claim 1, 2 or 4.
9. 9. A potting agent comprising a fluoroalkyl 2cyanoacrylate wherein the fluoroalkyl group contains 3-12 carbon atoms and the number 1 and number 2 carbon atoms of the fluoroalkyl group are fluorine free.
10. 10. A positive resist that is sensitive to electron beams or X-rays and contains recurring units derived from a fluoroalkyl 2-cyanoacrylate wherein the fluoroalkyl group contains 3-12 carbon atoms and the number 1 and number 2 carbon atoms of the fluoroalkyl group are fluorine free.

    1,9
11. 11. An adhesive composition comprising a compound as claimed in any one of Claims 1, 2 or 4, another 2cyanoacrylate, an anionic polymerisation inhibitor and a radical polymerisation inhibitor.
12. 12. An adhesive composition according to Claim 11 comprising sulphur dioxide and hydroquinone.
13. 13. An adhesive composition substantially as described in any of Examples 1-3.