GB2133019A - Rapid curing adhesive composition - Google Patents

Abstract

A rapidly curing adhesive composition comprises 100 parts by weight of polymerizable methacrylic acid ester, at least 0.5 part by weight of the salt of o-benzoic sulphimide and a tetrahydroquinoline, 0.05-2.0 parts by weight of a hydroperoxide and at least 0.5 part by weight of water.

Description

SPECIFICATION Rapid curing adhesive composition This invention relates to a rapid curing adhesive composition which cures in a very short period of time at ambient temperature in a narrow gap between two adjoining surfaces, in particular between metal surfaces, to provide a strong bond and good sealing effect. More particularly, this invention relates to an adhesive composition able to adhere to clean metal surfaces defining a narrow gap within one minute and thereafter reaching a working strength within a short time of several minutes to several tens of minutes.

It has become increasingly commom to construct or seal parts of electrical components and machinery using acrylic solventless adhesives to simplify operation and reduce the production costs over those incurred when employing a mechanical connection, particularly by enabling a series of operations in a line to be carried out with resulting increased efficiency. When performing operations in a line, a sufficient adhesive strength is naturally required before the next operation is to be carried out and hence it is important that the adhesion work be simple, the curing rate of the adhesives be very high, and the use of large amounts of adhesive does not irritate the human body, in particular an eye, the nose, and the skin of the person carrying out the bonding operations.However, cyanoacrylate adhesives and anaerobic adhesives which are typical acrylic solventless adhesives do not meet these requirements sufficiently satisfactorily.

Thus, cyanoacrylate series adhesives possess sufficiently rapid curing rate but since they irrititate the mucous membrane of the eye, nose, etc., when a large amount of such adhesive is used for in line work, a ventilator is required. Moreover, because such adhesives possess inadequate heat resistance and water resistance, they are unsuitable for construction uses.

On the other hand, since anaerobic adhesives are mainly composed of polyacrylate and the cured products of the adhesives are three-dimensionally crosslinked resins, they possess excellent adhesive strength, heat resistance, water resistance oil resistance, etc. However, since the curing rate is low, they cannot be used as such for in line work. More particularly, various anaerobic adhesives are proposed in for example Japanese Patent Publication No. 26,659/'72 and U.S. Patent No. 3,634,379. However, when using these adhesives, several tens of minutes are required for setting and it takes several hours or more to obtain a useful cured strength. if rapid curing of the adhesives is needed a complicated operation such as high-temperature heating and the use of a primer is required.Moreover, when the adhesives are used in large quantities in in line work, organic peroxides present in the adhesives as hardening agents, give off irritant vapours which cause irritation to the skin, eye and nose and have an undesirable smell. Accordingly, such adhesives are generally undesirable for practical use.

In general, an anaerobic adhesive is a one-part type adhesive mainly composed of polymethacrylate to which is added a hardening agent, a curing accelerator and a stabilizer for achieving satisfactory curing rate and stability on storage. A rapidly curing adhesive may generally be obtained using a strongly curing accelerator. However, an adhesive containing such a strongly curing accelerator possesses poor stability on storage and hence is unsuitable for practical use. It is possible to add a strongly curing accelerator directly before using the adhesive, but such a method is not only unsatisfactory to carry out but also gives rise to problems connected with the durability of the bond produced and the preservability of the adhesive after the addition of the curing accelerator.

As an alternative, the present inventors have already proposed anaerobic adhesive compositions having a relatively high curing rate and which do not contain irritating organic peroxides.

Instead these compositions contain a salt of o-benzoic sulphimide and the amine of general formula (1)

wherein R, and R2 independently represent a hydrogen atom or a methyl group. Such compositions are disclosed in Japanese Patent Publications Nos 39,480/'78; 47,266/'78, 28,176/'79; and 1958/'80. These adhesive compositions are able to give rise to bonding in a narrow space between metal surfaces within several minutes, with a working strength being reached in several hours.

However, as a result of various investigations for improving further the rapid curability of the adhesive compositions, it has been found that when a small amount of a hydroperoxide and an amount of water are added to the adhesive compositions, the compositions show an astonishingly high bonding speed such that a bond is formed in 10-60 seconds despite the composition being a one-part type adhesive composition.

Thus, according to the present invention, there is provided a rapidly curing adhesive composition which comprises 100 parts by weight of a polymerisable methacrylic acid ester, at least 0.5 parts by weight of a salt of o-benzoic sulphimide and an amine represented by the following general formula (1)

wherein R, and R2 independently represents a hydrogen atom or a methyl group, 0.05-2.0 part by weight of a hydroperoxide, and at least 0.5 part by weight of water.

The salt of o-benzoic sulphimide and the amine possessing the general formula (1) (hereinafter, the salt is referred to as s-amine) can be prepared by the methods described in the foregoing Japanese patent specifications of the present inventors. A typical example of the production method for a s-amine is shown in the preparative example which follows herein, although in general the s-amine can be easily obtained by performing an addition reaction between o-benzoic sulphimide and the amine of general formula (1) in almost equimolar amounts in an inert solvent such as ethanol and methyl ethyl ketone.

The amount of the s-amine used in the compositions of this invention is generally 0.5-5.0 parts by weight, preferably 1.0-3.0 parts by weight, per 100 parts by weight of the polymerizable methacrylic acid ester. If the amount of s-amine is less than 0.5 part by weight, the adhesive property of the composition is reduced and if the amount is over 5.0 parts by weight, no further improvement of the adhesive property is obtained.

Specific amines which may be present in the s-amine, are 1 ,2,3,4-tetrahydroquinoline, 6 methyl-i ,2,3,4-tetrahydroquinoline and 1 ,2,3,4-tetrahydroquinaldine. The s-amine has a polymerization initiating property when no organic peroxide is present and it has been discovered that the catalytic faculty of the s-amine is greaty increased in the presence of a small amount of a hydroperoxide and water.

The amount of hydroperoxide added is generally from 0.05-1.0 part by weight, preferably 0.1-0.6 part by weight per 100 parts by weight of the polymerizable methacrylic acid ester. In this invention a sufficient effect is obtained with such a small amount of hydroperoxide and it is unnecessary to add the hydroperoxide in an amount over 2.0 parts by weight as would be the case with conventional anaerobic adhesives. If the amount of the organic peroxide used is over 2.0 parts by weight, the adhesive composition emits a foul odour as well as being a major source of irrittation to the skin of the human body. Accordingly, it has hitherto been considered to be desirable to reduce the amount of the organic peroxide added to as low a value as possible, in particular, to less than 1.0 part by weight.Hoever, if the amount of the organic peroxide added is reduced below 0.05 part the bonding speed is reduced and the quality of the bonding strength is reduced, as in conventional adhesive compositions.

On the other hand, the adhesive composition of this invention undergoes very rapid curing and yields good bonding strengths even if the amount of the organic peroxide added is less than 0.5 part by weight. This is obviously very advantageous from the point of view of industrial hygiene.

Examples of the hydroperoxides which may be used in this invention are t-butyl hydroperoxide, p-menthane hydroperoxide, cumene hydroperoxide and diisopropylbenzene hydroperoxide.

Whilst in principle organic peroxides other than hydroperoxides may be used, in view of the small amounts to be used in such case the bonding rate is often unsatisfactory.

The amount of water added is generally from 0.5-5.0 parts by weight per 100 parts by weight of the polymerizable methacrylic acid ester and the addition of such relatively large amounts of water to a conventionally solventless adhesive imparts a rapid curability of the order of seconds to the adhesive composition of this invention. If the amount of water added is over 5.0 parts by weight, the bonding speed is not further increased and indeed the bonding strength tends to be reduced. Also, if the amount of water added is less than 0.5 part by weight, the rapid curability of the order of seconds is not obtained. A commercially available polymerizable methacrylic acid ester may indeed contain amounts of water as impurities.

However, these amounts of water have no effect on improving the bonding speed.

Particularly preferred polymerizable methacrylic acid esters for use in the compositions of this invention are the following systems (a), (b), and (c): System (a): The compounds represented by the following general formula (2) are used

wherein R3 repressents an alkylene group having 2-4 carbon atoms and n is an integer of 3-5.

System (b): A mixed system containing the compound shown by foregoing general formula (2) and less than 90% by weight of the system being constituted by a compound of general formula (3)

wherein R4 and R5 independently represent an alkylene group having 2-4 carbon atoms and 1 and m are independently 1 or 2, with 1 + mv 3.

System (c): A mixed system of 10-70% by weight of a compound possessing general formula (4)

wherein R6 represents an alkylene group having 2-4 carbon atoms and p is an integer of 1-8 and 90-30% by weight of the compound possesing foregoing general formula (3).

The compounds of general formula (2) in system (a) are the dimethacrylates of polyalkylene glycols and may be uniformly dissolved in the water which is a necessary component of the composition of this invention. Moreover, the compounds of general formula (3) serve to improve the heat resistance of the adhesive, but it is difficult to dissolve or disperse water uniformly in the compound alone and when the compound is mixed with the compound of general formula (2) at the mixing ratio shown for system (b), water can be uniformly dissolved or dispersed in the mixture. With an adhesive composition of this invention using the system (b), a particularly rapid curing is obtained when 1 + m 3, and if 1 + m > 3, the bonding speed tends to be reduced to some extent.

The compounds of general formula (4) in the mixed system (c) are hydroxyalkyl methacrylates or monomethacrylates of polyalkylene glycols. The compounds are used for the same reason as the compound of general formula (2) and are monomers particularly suitable for improving the bonding strength.

Practical examples of compounds of the general formula (2) are triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, pentaethylene glycol dimethacrylate, tripropylene glycol dimethacrylate, etc. Practical examples of compounds possessing general formula (3) are the dimethacrylate of an addition product of bisphenol A and 2 mols of ethylene oxide, the dimethacrylate of an addition product of bisphenol A and 3 moles of ethylene oxide, the dimethacrylate of an addition product of bisphenol A and 2 mols of propylene oxide and the dimethacrylate of an addition product of bisphenol A and 2 mols of butylene oxide.

The polymerizable methacrylic acid esters of the foregoing systgems (a), (b), and (c) are particularly preferred in this invention but other polymerizable methacrylic acid esters may also be used. Examples of such other polymerizable methacrylic acid esters are polymethacrylates of polyhydric alcohols, such as trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, glycerol trimethacrylate, neopentyl glycol dimethacrylate, ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; monomethacrylates, for example methoxy polyethylene glycol methacrylate, tetrahydrofurfuryl methacrylate and lauryl methacrylate; epoxy methacrylates and urethane polymethacrylates.Since these polymerizable methacrylic acid esters other than methoxy polyethylene glycol methacrylate cannot dissolve or disperse water uniformly therein, it is preferred to use the polymerizable methacrylic acid ester together with the compound of foregoing general formula (2) or (4).

The anaerobic adhesive compositions of this invention as described above are one-part type adhesive compositions having very rapid curability, which is almost as rapid as that of a cyanoacrylate series adhesive, when positioned in the gap between two clean metal surfaces in a closely abutting relationship, and can be suitably used in line work. For example, the adhesive composition of this invention has an instantaneous bonding property such that it can be used when bonding polished metal surfaces to each other or when bonding a polished bearing and a polished shaft, a polished rotor and a polished shaft, when bonding takes place within one minute at ambient temperature and working bonding strengths are obtained in 5-15 minutes.

The adhesive compositions of this invention also show a remarkable rapid curing when used in a threaded assembly having a relatively large clearance, unlike when using a conventional anaerobic adhesive, and also prove to be able to strongly bond for example plated articles or stainless steels the bonding of which is normally difficulft without the use of a primer when using conventional adhesives. In each case bonding in a very short period of time is achieved.

Furthermore, in spite of curing very rapidly the adhesive compositions of this invention have a good stability on storage without the need to employ any specific preserving method as is necessary with cyanoacrylate adhesives. The compositions of this invention can indeed be stably preserved for a long period of time without undergoing change in their properties thereof by merely placing the composition in a light-shielding polyethylene container in an amount occupying about half of the volume of the container. Finally, the adhesive compositions of this invention are comfortable to work with since they do not contain a large amount of organic peroxides or free amines giving rise to irritation and unpleasant odours.

In summary, thus, the adhesive compositions of this invention contribute greatly to increased efficiency and safeness when carrying out bonding work. The ahdesive compositions of this invention can contain appropriate Amounts of additives such as colouring agents, thickeners, thixotropic agents, stabilisers and plasticisers.

The invention will now be further described in detaii by the following examples which include a preparative example and comparative examples. Unless otherwise indicated, all parts and percentages are expressed on a weight basis.

Preparative example 1 mole of o-benzoic sulphimide was added to 1 litre of ethanol and after heating the mixture to 40"C, 1.1 mils of 1,2,3,4-tetrahydroquinoline was gradually added thereto with stirring. The resultant mixture was then further stirred for one hour and then allowed to stand overnight at 5"C to precipitate a crystalline salt. Ethanol and excess 1 ,2,3,4-tetrahydroquinoline were removed from the reaction mixture by filtration and the residue was dried under reduced pressure to provide the 1,2,3,4-tetrahydroquinoline salt of o-benzoic sulphimide (hereinafter, the salt is referred to as STQ). The structural formula of STQ is shown below.

The 6-methyl-l ,2,3,4-tetrahydroquinoline salt of o-benzoic sulphimide (hereinafter, the salt is referred to as SMQ) and the 1 ,2,3,4-tetrahydroquinaldine salt of obenzoic sulphimide (hereinafter, the salt is referred to as SOYA) were obtained respectively by following the same procedure as above but using 6-methyl-1,2,3,4-tetrahydroquinoline and 1,2,3,4-tetrahydroquinaldine in place of 1 ,2,3,4-tetrahydroquinoline.

The salts thus obtained were all lemon-yellow crystals and the elemental analysis values thereof coincided well with the calculated values shown in Table 1, Table 1 Salt Carbon (%) Hydrogen (%) Nitrogen (%) Found Calc. Found Calc. Found Calc.

STQ 60.75 60.74 5.00 5.10 8.80 8.85 SMQ 61.60 61.80 5.27 5.49 9.00 8.48 SQA 61.30 61.80 5.40 5.49 8.60 8.48 EXAMPLE 1 1.5 Parts of an s-amine prepared in the preparative example were dissolved in 100 parts of tetraethylene glycol dimethylacrylate (hereinafter, referred to as TEDM) with heating and the solution was then cooled to room temperature. 0.3 Part of cumene hydroperoxide and 2.0 parts of water were added to the solution which was then subjected to sufficient stirring to produce an adhesive. The setting time, the shear strength after 1 5 minutes, the final shear strength, and the days required for gelling the adhesive at 50"C (gelling days) were measured for the adhesives obtained and the results are shown in Table 2.

Table 2 Adhesive s-amine Setting Shear Final Gelling present time strength shear days at (sec.) after 1 5 strength 50"C min. (kg/cm2) (kg /cm2) 1 STQ < 15 200 210 > 14 2 SMQ < 15 190 262 > 14 3 SQA < 15 160 229 > 14 It is clear from the results shown in the above table, that the setting times were less than 1 5 sec. in all cases and the shear strength after 1 5 minutes already reached 1/2 of the final shear strength (practical strength). The respective properties were measured by the following methods according to the standard JAI-6-1979 of the Society of the Adhesive Industry of Japan.

Setting time: An adhesive is coated on a degreased iron shaft 1 5 mm in diameter, the iron shaft thus coated with the adhesive is inserted into a degreased bearing (NTN 6202) and bonded thereto.

They are allowed to stand at 23"C, and the period of time required until the shaft is not easily withdrawn by hand is measured, this time relating to the initiation time of bonding.

Shearing strength after 15 minutes and final shearing strength: After allowing the bearing shaft bonded as described above to stand for 1 5 minutes at 23"C, the compressive shear strength was measured. The final shear strength was the shear strength after 24 hours. In addition, the measurement was performed at a punching rate of 100 mm/min.

Gelling days at 50"C 50g of an adhesive are placed in a polyethylene container having a volume of 100 ml, the container containing the adhesive is allowed to stand in a drying oven at 50"C, and the days required until the adhesive becomes viscous or is gelled are measured. If the adhesive shows no unusual change lasting more than 10 days, the adhesive is estimated to be stable longer than a half year to one year at ambient temperatures.

EXAMPLE 2 and Comparative Examples 1, 2, and 3 By following the same procedure as in Example 1 and using compositions composed of 100 parts of TEDM, 1.5 parts of STQ, 0.05 to 1.0 part of cumene hydroperoxide, and 2.0 parts of water, adhesives were prepared and the properties of the adhesives were measured as in Example 1, the results thus obtained being shown in Table 3. In addition, as comparative examples, the same procedure as above was followed using the systems containing 0, 0.03 part, and 2.0 parts of cumene hydroperoxide and the results obtained are also shown in Table 3.

Table 3 Adhesive Amount of Setting Shear Final Gelling No. cumene time strength shear days at hydro- (sec.) after 1 5 strength 50C peroxide min. (kg/cm2) (part) (mg/cm2) 4 0.05 30 1X 210 > 14 5 0.10 < 15 153 220 > 14 6 0.30 < 15 153 220 > 14 7 0.60 < 15 183 230 > 14 8 1.0 < 15 166 240 > 14 Comparative Example 1 0 < 300 0 10 > 14 Comparative Example 2 0.03 65 20 200 4 Comparative Example 3 2.0 < 15 188 240 > 14 It is clear from the results shown in Table 3 that when the amount of cumene hydroperoxide was below 0.05 part, the setting time was over one minute and when the amount thereof was over 1.0 part, no further increase in properties was observed and, on the contary, in such a case the adhesives emitted an irritating odour.When the amount of cumene hydroperoxide was more than 0.05 part, the time for achieving full bonding was long and the adhesives tended to be easily gelled.

EXAMPLE 3 and Comparative Examples 4, 5 and 6 The same procedure as in Example 1 was repeated using compositions composed of 100 parts of TEDM, 0.5-5.0 parts of STQ, 0.3 part of cumene hydroperoxide, and 2.0 parts of water, and the properties of the adhesive prepared were measured. The results obtained are shown in Table 4. In addition, the same procedure as above was followed in comparative examples, using 0, 0.3 part and 6 parts of STQ. The results obtained are shown in Table 4.

Table 4 Adhesive Amount Setting Shear Final Gelling No. of STQ time strength shear days at (part) (sec.) after 15 strength 50C min. (kg/cm2) (ks/cm2) 9 0.5 25 207 200 > 14 10 1.0 < 15 158 200 > 14 11 3.0 < 15 202 240 > 14 12 5.0 < 15 165 230 > 14 Comparative Example 4 0 < 300 0 0 > 14 Comparative Example 5 0.3 110 132 200 > 14 Comparative Example 6 6.0 < 15 242 240 1 As is clear from the results shown in Table 4, when the amount of STO added was less than 0.5 part, a setting time of less than 1 minute was not obtained and if the amount was over 5.0 parts, the properties of the adhesive were further improved and, on the contrary, the adhesive showed a readily gelling tendency. In the system containing no STQ the adhesive did not show bonding even after 24 hours.

EXAMPLE 4 and Comparative Examples 7, 8 and 9 The procedure of Example 1 was repeated using 100 parts of TEDM, 1.5 parts of STQ, 0.3 part of cumene hydroperoxide, and 0.5-3.0 parts of water to produce adhesive compositions.

The properties of these compositions were measured as in Example 1, the results being shown in Table 5. The same procedure as above was followed using systems containing 0, 0.1 part, and 6.0 parts of water and the results obtained are also shown in Table 5.

Table 5 Adhesive Amount Setting Shear Final Gelling No. of time strength shear days at water (sec.) after 1 5 strength 50"C (part) min. (kg/cm2) (kg/cm2) 13 0.5 ' 55 192 250 > 14 14 0.8 50 235 230 > 14 15 1.0 40 244 220 > 14 16 3.0 20 198 240 > 14 Comparative Example 7 0 > 120 15 240 > 14 Comparative Example 8 0.1 > 120 65 240 > 14 Comparative Example 9 6.0 > 15 32 170 6 As is clear from the results shown in the above table, when the amount of water was greater than 0.5 part, the bonding rate increase and the greater the amount of water added, the higher the curing rate was. However, when the amount of water increased above, the bonding strength was reduced and the adhesive showed a tendency to gell easily.

EXAMPLE 5 1.5 parts of SMG was dissolved under heating in a mixture of 50 parts of the dimethyacrylate of an addition product of bisphenol A and 2 moles of ethylene oxide and 50 parts of one of the OH group-containing methacrylic acid esters shown in Table 6 and after cooling the solution obtained to room temperature, 0.3 part of the cumene hydroperoxide, and 1.7 parts of water were added to the solution as in Example 1 to provide adhesives whose properties were measured as in Example 1. The results of the measurement are shown in Table 6.

As is clear from Table 6, the adhesives containing OH-group-containing methacrylic acid esters show high shear strength as well as rapid curability.

Table 6 Adhesive OH group- Setting Shear Final Gelling No. containing time strength shear days at methacrylic (sec.) after 1 5 strength 50"C acid ester min. (kg/cm2) (kg/cm2) 17 2-hydroxyethyl < 15 179 320 > 14 methacrylate ss 18 2-hydroxypropyl * < 15 345 370 > 14 methacrylate 19 2-hydroxybutyl < 15 233 241 > 14 methacrylate 20 Polypropylene 20 226 286 > 14 glycol monomethacrylate EXAMPLE 6 The procedure of Example 1 was repeated but using a composition composed of 100 parts of a mixture of TECkM and one of the polymerisable monomers shown in Table 7, 1.5 parts of STQ, 0.3 part of cumene hydroperoxide and 2.0 parts of water to prepare a series of adhesives.

the results of measurements carried on the adhesives are shown in Table 7. It is clear from the results that good adhesive properties altogether were obtained.

Table 7 Adhesive Composition of polymerizable Properties No. methacrylic acid ester Setting Tensile Final Gell TEDM Compound of formula (3) time strength shear ing (part) (sec.) after 15 strength days R4, R5 # + m (part) min. (kg/m2) at 50 C (kg/cm2) 21 30 -CH2#CH2- 2 70 20 210 250 > 14 22 10 -CH2#CH2- 3 90 45 143 240 > 14 23 35 -CH2#CH2- 3 65 30 214 250 > 14

If rl re II\ 0 0 CV rl N CY O Cr) CV rl c c 24 50 -CR2.CR- 2 50 45 120 220 > 14 CR3 s m l uu Uu es cs u Sc u N l o o un wr N t > J Comparative Example 10 An anaerobic adhesive having a well-known composition was prepared and the properties of the adhesive were compared with those of the adhesives of this invention produced in inventive examples herein, the results being shown in Tables 8, 9 and 10. The results showed that the adhesive compositions of this invention underwent a very rapid curing.

Composition of the comparative adhesive: TEDM 100 parts N,N-dimethyl-p-toluidine 1.0 part o-benzoic sulphimide 0.2 part p-benzoquinone 0.03 part cumene hydroperoxide 2.0 parts A. Comparison in bonding rate between bearing and shaft: Using the bearing and the shaft referred to at the end of Table 1, the bond strength (kg/cm2) was measured for each definite period of time and the results thus obtained are shown in Table 8.

Table 8 Bonding time 1 2 5 15 1 4 24 min. min. min. min. hr. hrs. hrs.

Comparative adhesive 0 0 0 9 30 220 210 Adhesive No. 1 of the invention 1 30 180 200 240 220 210 Adhesive No. 18 of the invention 11 118 165 345 330 380 370 B. Comparison of surface bonding rates: Using the method of ASTM D1062-51, cleavage test pieces of SS41 iron polished using 240* sand paper and degreased were bonded at 23"C and the cleavage strength was measured at specific time intervals, the results being shown in Table 9.

Table 9 Bonding time 1 5 15 30 4 24 min. min. min. min. hrs. hrs.

Comparative adhesive 0 0 0 30 38 25 Adhesive No.

22 of the invention 18 25 35 24 25 25 Adhesive No.

17 of the invention 30 32 88 122 124 126 Unit: kg/inch C. Comparison in adhesive property for bolt and nut: Using a 3/8" i.e. 9.5 mm and nut, the setting time (the time until the nut could not be turned by hand after bonding at 23"C) and return torque after 24 hours were measured, the results being shown in Table 10. In addition the return torque was shown by the torque (average value) on turning 1 /4, 1 /2, 3/4, and 1 turn, the torque being determined by measuring the rotation torque required for loosening the bolt/nut after bonding using a torque wrench.

As is clear from the results shown in Table 10, the adhesive of this invention produced strong adhesion in a short period of time for materials such as stainless steel, galvanized iron, for which a conventional or comparative adhesive showed slow bonding rate in the absence of a primer.

Table 10 Material of Comparative adhesive Adhesive No. 22 bolt and nut of the invention Setting Return Setting Return time torque time torque (min.) (kg/cm2) (min.) (kg/cm2) Iron 30 145 2 205 Stainless 60 1 70 10 220 steel Aluminium 40 120 4 240 Zinc 100 90 4 315 plated iron Chromium 90 205 5 240 plated iron Nickel 40 245 5 265 plated iron

Claims (11)

1. A rapidly curing adhesive composition which comprises 100 parts by weight of a polymerizable methacrylic acid ester, at least 0.5 part by weight of a salt of o-benzoic sulphimide and an amine represented by the following general formula (1)

wherein R, and R2 independently represent a hydrogen atom or a methyl group, 0.05-2.0 part by weight of a hydroperoxide, and at least 0.5 part by weight of water.

2. A composition as claimed in claim 1, which contains 0.5 to 5.0 parts by weight of said salt per 100 parts of the polymerizable ester.

3. A composition as claimed in claim 2, which contains 1 to 3 parts by weight of said salt per 100 parts of the polymerizable ester.

4. A composition as claimed in any of claims 1 to 3, which contains from 0.05 to 1.0 parts by weight of the hydroperoxide per 100 parts by weight of the polymerizable ester.

5. A composition as claimed in claim 4, which contains from 0.1 to 0.6 parts by weight of the hydroperoxide per 100 parts by weight of the polymerizable ester.

6. A composition as claimed in any one of the preceding claims, wherein the hydroperoxide is selected from t-butyl hydroperoxide, p-menthane hydroperoxide, cumene hydroperoxide and diisopropylbenzene hydroperoxide.

7. A composition as claimed in any one of the preceding claims, which contains water in an amount of 0.5 to 5.0 parts by weight per 100 parts by weight of the polymerizable ester.

8. A composition as claimed in any one of the preceding claims wherein the polymerisable methacrylic acid ester component is constituted by one of the following systems (a), (b) and (c); (a) a compound represented by the general formula (2)

wherein R3 represents an alkylene group having from 2-4 carbon atoms and n represents an integer of from 3-5.

(b) a mixture of not more than 90% by weight of a compound of general formula (2) and up to 10% by weight of a compound represented by general formula (3)

wherein R4 and R5 independently represent an alkylene group having from 2-4 carbon atoms and 1 and m are independently 1 or 2, the sum of 1 and m being < 3.

(c) a mixture of 10-70% by weight of a compound represented by general formula (4)

wherein Rs represents an alkylene group having from 2-4 carbon atoms and p represents an integer of from 1-8 and 90-30% by weight of the compound of general formula-(3).

9. A composition as claimed in any one of the preceding claims, wherein the amine of general formula (1) is 1 ,2,3,4-tetrahydroquinoline, 6-methyl-l ,2,3,4-tetrahydroquinoiine or 1 ,2,3,4-tetrahydroquinaldine.

10. A rapidly curing adhesive composition which is any one of compositions 1 to 25 set out in the foregoing Examples.

11. A method of forming a bond between two clean metal surfaces, which comprises carrying out solventless bonding between the surfaces using an adhesive composition as claimed in any one of the foregoing claims.

1 2. A method of forming a bond between two clean metal surfaces, substantially as described in any one of the foregoing Examples 1 to 6.