FR2528440A1 - ADHESIVE COMPOSITION IN TWO PARTS WITHOUT SOLVENT - Google Patents

Abstract

THE INVENTION RELATES TO ADHESIVES. IT CONCERNS AN ADHESIVE COMPOSITION IN TWO PARTS INCLUDING: A. AS FIRST PART A RESIN SYSTEM INCLUDING: 1 AT LEAST ONE POLYMERISABLE ACRYLATE OR METHACRYLATE MATERIAL, 2A RADICAL POLYMERIZATION INITIATOR CHOSEN FROM PEROXYDOS, PEROXYDALS, PEROXYDALS, PEROXYDALS, PEROXYDALS ; AND B. AS A SECOND PART A RESIN SYSTEM CONSISTING OF: 1 AT LEAST ONE POLYMERISABLE ACRYLATE OR METHACRYLATE MATERIAL, 2 A SOLVENT-FREE ACCELERATOR SYSTEM INCLUDING A TRANSITION METAL SALT. APPLICATION TO THE BONDING OF VARIOUS MATERIALS, ESPECIALLY WITH THICK SEAMS.

Description

The present invention relates to an adhesive system

  solvent-free sif in two parts, characterized by excellent

  slow filling capacities of interstices and a

  fast curing, as well as a method for adhesive bonding surfaces using this system. Two-part adhesive compositions are well known for ethylenically unsaturated, free radical curable adhesive systems.

  these adhesive compositions have required the use of

  solvents as vehicles for their primer or accelerator systems. Usually, the primer is

  applied on the surface before the deposit of the poly-

  The solvent carrying the primer is usually allowed to evaporate from the surface prior to contact with the polymerizable portion. Typical examples of patents in this field are US Pat. No. 4,081,308.

  and 4,052,244, both in the name of Mr. Skoultchi.

  vets have adhesive compositions in two parts.

  in which the first part is a polymerizable acrylic monomer and the second part is an accelerator in a solvent as a vehicle Other

  patents relating to adhesive compositions

  in two parts containing polymeric solutions.

  The elastomers in vinyl monomers are US Pat. Nos. 3,810,407, 3,962,272, 4,112,013, 4,118,436, 3,994,764, 3,832,274 and 4,138,449. These systems are used in the manufacture of stubborn acrylic products. also use solvents as a carrier for the accelerator portion of the adhesive composition Anaerobic compositions have effectively used primers and accelerators as a means for treating a surface prior to depositing the polymerizable portion

  of the adhesive composition The primers have been traditionally

  These are preferably kept separate from the adhesive composition and dissolved in a carrier solvent, such as trichloroethane or the like. Examples of anaerobic compositions that employ, though optionally, solutions in a finishing solvent to accelerate cure are U.S. Patent Nos. 2,895,950, 3,043,820 and 3,218,306, among others.

  The present invention relates to composi-

  two-part adhesives that are characterized by fast curing and excellent curing

  in bulk, for example an excellent ability to fill

  The present invention also relates to a method for assembling surfaces in which one is able to

uses the adhesive composition.

  More particularly, the present invention relates to an adhesive composition comprising (A) as a first part, a resin system comprising (1) at least one polymerizable acrylate or methacrylate material;

  (2) a radical polymerization initiator

  calaire selected from peroxides, hydroperoxides, peresters, persalts and peracids; (3) optionally a sulfimide; and (4) optionally a hydrazine derivative; and (B) as a second part, a resin system comprising (1) at least one polymerizable acrylate or methacrylate material; (2) a solventless accelerator system comprising a transition metal salt; and (3) possibly a co-accelerator

  amine with the transition metal salt.

  The present invention describes a two-part composition that is new in that neither of the two parts of the composition contains a solvent as a carrier for the accelerator or primer components. While the prior art described the polymerizable portion of an adhesive composition as to be contained only in one part, while

  that the second part included an accelerating solution

  or solvent in an organic solvent, the pre-

  This invention requires that the polymerizable material, for example a vinyl-type monomer, be present in both parts of the adhesive composition according to the invention.

  the invention, the two parts of the adhesive composition

  sive preferably contain similar proportions

  resins of a vinyl-type monomer, which cures by a radical reaction The initiators of the radical reaction must be maintained in a part of

  adhesive and metal-based accelerators

  should be maintained in the other part.

  Each part remains stable until it is melange

  with the other, after which a hardening of the adhesive composition occurs It is possible for some compounds known as accelerating the production of free radicals to be in the same part

  radical initiators without causing any problems.

  stability Sulfimides and hydrazine derivatives

  However, the transition metal salts and complexes, which are necessary for the present invention, must not be incorporated into the same part.

  partly as initiators or hydrazine derivatives.

  Although it is not absolutely necessary

  equivalent quantities of polymerised

  are present in both parts, it is recommended that this be the case in order to facilitate the diffusion of the various constituents in each part (in particular the initiators and accelerators).

  rheology of the two parts must be substantially similar

  in order to promote efficient mutual mixing of the initiator in one part with the accelerator in the other part, and to effect uniform hardening

  in all the polymerizable material.

  An advantage over the prior art

  The present invention provides that the accelerators are dispersed more efficiently throughout the entire adhesive composition, rather than simply applying an accelerating solution.

  on the surface of the adhesive.

  in mass hardening and interstice filling capacity can be attributed to this. It is not necessary to premix the two components prior to deposition on one surface A layer of one part of the adhesive composition may be placed on one surface and one layer of the other

  can be placed on another surface, both surfaces

  these being then mated so that the layers

  respective ones are in contact with each other.

  Although any vinyl-type polymers are usefully usable, the materials

  Preferred polymerizable compounds are acrylates and methacrylates.

  lates, which can be mono or poly-functional.

  Adjusted cure speeds are

  possible independently of the surface of the supports.

  Prior coating of surfaces with accelerating solutions, as in the prior art, is not necessary Curing in spaces

  relatively large at the glue line is now

  possible in relatively short times.

  In practice, the adhesive composition can be applied by several methods. The two parts of the adhesive composition can be applied.

  one on one surface and the other on a second sur-

  face and place the two surfaces in contact with each other; or, alternatively, a layer of one part of the adhesive composition may be applied to a first surface, a layer of the other portion applied to the first layer and a second uncoated surface to

  contact with the first surface covered with both

  Another alternative, especially usable for slidable parts or threaded parts, is to place each portion of the adhesive composition side by side on a first surface and to place a second surface in contact with the first surface. coated, to move the two

  surfaces with respect to each other and thus

  The less preferred alternative is to mix the two parts of the adhesive composition together beforehand.

  deposit on surfaces Once the parts coated

  The adhesive composition is cured at room temperature to form a bonded joint in a relatively short time. At least one polymerizable material must be present in each of the two parts of the present invention Although any reactive compound of the allylic or vinyl type which undergoes radical polymerization is actually useful, monomers which are esters of the acrylate type are preferred. and methacrylates Acrylate and methacrylate monomers

  polymerizable compounds can be mono-functional, poly-

  functional or a combination of both In a way

  In general, examples of the monomers are not limited to

  Suitably, those selected from the group consisting of alkyl acrylates, cycloalkyl acrylates, alkyl methacrylates, cycloalkyl methacrylates, alkoxy acrylates, alkoxy methacrylates, alkylene diacrylates, and alkylene dimethacrylates among the preferred mono-functional monomers. are methyl methacrylate, lauryl methacrylate, 2-ethyl hexyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate and t-butyl methacrylate. monomers that have high boiling points and low

  volatility, including monomers such as metha-

  tetrahydrofurfuryl crylate, methacrylate

  cyclohexyl, isobornyl methacrylate, methacrylate

  hydroxyethyl late and hydroxypropyl methacrylate.

  The mono-functional monomers mentioned below

  above can be represented generally by the formula:

I CH 2 = C-CO OR 2

R 1

  wherein R 1 is H, CH 3 or lower alkyl group

  R is H or an alkyl, alkoxy, cycloalkyl

coyle or alkylene.

  The effective amount of the acrylate monomer

  mono-functional polymerizable material for use in

  compositions may vary slightly depending on the

  particular properties desired, but is gener-

  between about 1 and about 90% of the weight of the

  composition and preferably between about 15 and

  80% by weight, in particular between about 15 and about 40% of the weight of the composition Adjustments between these limits will be made easily by

the skilled person.

  It may be advantageous to also add a polyfunctional monomer to the composition. When making such an addition, it will generally be necessary to

  about 1 to about 90% of the weight of the composition.

  according to the particular polyfunctional monomer, and preferably from about 15 to about 40% of the weight of the composition. Preferred polyfunctional monomers

  are dimethacrylates of various glycols These mono-

  are described in US Pat. No. 3,218,305 and are of the general formula:

R R

I 5

1 II RO O (CH 2) m C 4 p k

  wherein R is H, an alkyl or hydroxyalkyl group

6

  C1-4 alkyl or R50 CH 2-; R is H, a halogen or a

R 45 5

  C 14 alkyl group; R is H, OH or R 50-; R is

6 14

  CH 2 = CR C = O-; m is an integer, preferably 1 to 8; k is an integer, preferably 1 to 20;

and p is 0 or 1.

  Examples of some preferred glycol dimethacrylates of this formula are dimethacrylate

  polyethylene glycol and dipro- dimethacrylate

  pylene glycol, to name a few.

  Other monomers polymeric acrylic esters

  The compositions which can be used are described in US Pat. No. 4,018,851, having the general formula:

R 8 O

  Wherein R 8 is selected from the group consisting of hydrogen, chlorine and methyl and ethyl radicals; R 7 is a divalent organic radical selected from lower alkylene radicals of 1-8 carbon atoms, phenylene and naphthylene; W is a polyisocyanate radical; E is a polyol radical or

  aromatic polyamine, heterocyclic or cycloaliphatic

  that, preferably, a diol, in particular a diol of a cycloaliphatic compound; d is 1 or 0; i is O when d is 0, and otherwise is one less than the number of reactive hydrogen atoms of E; Z is (1) a polymer grafted or copolymerized alkylene ether polyol radical or (2) a polymeric methylene ether polymer or copolymer radical giving a group of polymerizable monomers described in US Pat. No. 3,993,815; z is an integer equal to the valence of Z; an asterisk indicates a urethane bond

  (-NH-CO-O-) or ureide (-NH-CO-NH-).

  Monomers generally characterized as polyurethanes or polyureas, as described in US Pat. No. 3,425,988, can also be used effectively. These monomers are formed by the reaction of an organo polyisocyanate and an acrylic ester having a hydrogen atom. active in the non-acrylic portion of the ester These monomers may be represented by the general formula:

IV (A-X-CO N) B

  where X is -O or -R 9 N-; R 9 is selected from H and lower alkyl groups of 1 to 7 carbon atoms

14 _ 10

  carbon; A is CH 2 = CR CO OR 1 -; R 10 is H or CH R is a lower alkylene radical of 1 to 8 carbon atoms, phenylene or naphthylene; N is an integer from 2 to 6 inclusive; and B is a polyvalent alkyl, alkenyl, cycloalkyl, aryl, aralkyl, alkoxyalkylene, aryloxy-arylene or

  heterocyclic, substituted or unsubstituted.

  Finally, polyurethane urethane-acrylate monomers are

  Merisables described in US Patent Application No. 356,679 in the name of O'Sullivan, filed May 2, 1973, now abandoned, particularly Example 3, may be used. Typical monomers of this type have the general formula: he 13212

V (EO 2 = CR COOR 3 OCO NH) 2 R

  wherein R 1 is H, CH 3, C 2 H 5 or Cl; R 12 is a C 22 20 alkylene, alkenylene or cycloalkylene radical or an arylene, alkarylene, aralkarylene, alkoxyalkylene or C 6-40 aryloxyarylene radical which may be substituted with 1 to 4 chlorine atoms or with 1 to 3 amino or mono groups or di (C 1-3 alkyl) amino or

At R 13

  C 1-3 alkoxy is one of the following groups minus one hydrogen atom: (a) a C 1 -C 8 hydroxyalkyl or aminoalkyl group; (b) C 1-6 alkyl (C 1-6 alkyl) amino-C 1-8 alkyl group; or (c) a hydroxyphenyl, aminophenyl, hydroxynaphthyl or aminonaphthyl group which may be further substituted by an alkyl, alkylamino group

  or dialkylamino, each alkyl group in the radicals

  indicated in (c) containing up to about 3 ato-

  Among these monomers, the preferred compositions contain either the monomer VI, of formula: (CH 2 / C r CH 3) C (CH 3)

  VI H 2 = C (CH 3) COOC 3 H 6 OCONH NHCO O

is the monomer VII, of formula:

H

  VII (CH 2 = C (CH 3) COOCH 2 CH 2 OCONH NHCO PR

  or both (PR represents an oligomer residue of

propylene triol).

  Mixtures of some or all of the above polymerizable acrylic ester monomers are also useful. The radical polymerization accelerators of the present compositions are generally used with good results at concentrations of less than 10% by weight, the preferred range being from about 0.1% to about 0.75% Sulfimides are the preferred group of radical accelerators, the species

  preferred being 3-oxo-2,3-dihydrobenz (d) isothiazole

  1,1-dioxide, commonly known as benzoic acid sulphimide or saccharin Tertiary amines can also be used as accelerators for the production of

  free radicals, the preferred amine being N, N-dimethyl-

  paratoluidine Acids having a p Ka not exceeding 6 as described in US Pat. No. 4,180,640

  in the name of Melody, are also useful as accelerators.

  Hydrazine derivatives of the type described in US Patent No. 4,321,349 to R Rich, incorporated herein by reference, have been found to be very effective in the present compositions. The preferred hydrazine is 1-acetyl-2- phenyl hydrazine Useful hydrazines generally have the formula:

R 17-NRNH-NH-CO-R 18

  wherein R 17 and R 18 may be the same or different and are straight or branched chain C 6 alkyl radicals, C 1 -C 4 acyl radicals or C 1 -C 4 aryl radicals. are in sufficient quantities to

  accelerate the polymerization at room temperature.

  The transition metal accelerators are preferably a salt or complex of copper, nickel, cobalt or an ion. Examples of these preferred accelerators are copper octanoate, naphthenate

  copper, copper ethylhexanoate and acetylacetone

  copper nate, among others It is better that

  the transition metal accelerator is solu-

  The transition metal accelerator must be maintained in the part of the adhesive composition which does not contain the radical initiator or the hydrazine derivative. The relevant part of the adhesive composition contains the accelerator. transition metal base in an effective amount for curing the adhesive composition -when the two parts are brought into close contact with each other, or preferably mixed.

  proportion is effective in hardening a mixture of

  substantially equalities (in volume) of the two parts.

  Initiators may be of the peroxy type, or organic hydroperoxy; of the perester or peracid type; or of the persalt type. The perester type and the peroxide type are particularly useful, among which t-butyl perbenzoate, t-butyl peroctanoate and cumene hydroperoxide are preferred. The initiators are

  usually used at a rate of about 0.1%

  10% by weight of the composition.

  Useful free radical initiators include

  are also those that can be broken down by the action of heat to produce free radicals.

  also include other polymerization catalysts

  Such compounds may be readily selected by one of ordinary skill in the art. For a more detailed discussion, see US Pat. Nos. 3,043,820.

3,691,438, 3,616,640 and 3,832,274.

  Inhibitors and chelators, well known

  in the art to give stability to

  polymerization, are optional, but recommended

  Inhibitors useful in this

  are usually selected from the group consisting of hydroquinones, benzoquinones,

  naphthoquinones, phenanthroquinones, anthrax-

  quinones and substituted derivatives of any

  In addition, various phenols can be used as inhibitors, the most preferred being 2,6-di-tert-butyl-4-methyl phenol among the chelators

  which may possibly be present in the

  Adhesive, Beta-Dicetones and Ethylenediaminetetraacetic Acid (EDTA) Salt Both inhibitors and chelators can be used

  effectively in amounts of about 0.1 to about

  1% by weight, with no adverse effect on speed

  hardening of the polymerization adhesive composition

  Crosslinking agents, optionally

  in the range of about zero to about 10% of the weight of the composition, include

  such as copolymerizable dimethacrylates.

  Thickness, viscosity or thixo-

  desired tropics may vary depending on the application

  concerned Thickening agents, plastics

  other diluents and other agents common in the art may be used in a manner

  any reasonable reason for producing the characteristics

desired.

  The invention will be better understood from the following examples, which should not be construed as limiting in any way the

scope of the invention.

Example 1

  A composition was prepared according to

  invention using the following ingredients.

  All percentages by weight in these examples are

  based on the weight of the relevant part of the

adhesive.

  Part One Urethane-Acrylate Sequence Resin (1) Hydroxyethyl methacrylate Cumene hydroperoxide 1-acetyl-2-phenyl hydrazine Sulfimide benzoic Acrylic acid Chelating agent Second part Urethane-acrylate block resin (1) Hydroxyethyl methacrylate Copper octanoate Chelator% weight 36.31 58.45 0.94 0.47 0.42 2.00 1.04% by weight 28.00 69.70 2.00 0.30 (1) See US Patents 4,309,526 and 4 295 409 A linear cordon of the first part was

  distributed on a cylindrical surface of magnetically

  ceramic tick A cord of equal size of the

  second part was distributed on top of the first

  The first portion and a cadmium surface have been mated with the ceramic surface so that the surfaces are in close contact with each other and the portions of the adhesive are mixed together. The setting of the adhesive composition took place at room temperature in about twenty (20) seconds. The seam bonded between the surfaces was subjected to tensile shear strength tests and found to have hardened to give

  a strong bonded seal in a short time.

  The same test was carried out using the above composition and using a galvanized surface instead of the cadmium plated surface and obtained

similar results.

Example 2

  A composition according to the present invention was prepared using the ingredients of Example 1, except that the concentration of the metal was varied.

  in the second part Table I below

  below indicates tensile shear strengths (M Pa) at various thicknesses of

  depending on the hardening time, for several

  transition metal centrations The witness is a

  organic chlorine solution of a transition metal salt

  copper (octanoate) and an amine

  represents a typical finishing solution that is used

  used to coat surfaces, especially

  inactive faces like cadmium, before depositing the

  polymerizable portion of the first part of

this invention.

  This example shows that the compositions according to the invention have excellent curing speed, tensile shear strength and thick joint hardening properties with clearances between the 0.25 mm and 0 inch overlap portions. , 50 mm, the control sample exhibited only a low fixation resistance, while

  the present composition exhibited excellent resistance

  for these games at the collure line.

TABLE I

2% of octa-

4% of octa-

8% of octa-

  copper (copper) copper (1) (2) Adhesive thickness / curing time M Pa Pa 0/60 s 0/120 s 0/300 s 0/24 h 0.25 mm / 30 min 0.50 mm / 30 min 0.62 3.51 6.20 13.10 7.31, 79 1.10 4.14 8, 96 13.79 9.93 11.72

2.00 6.89

4.48 8.27

8.41 9.93

12.75 12.82

  11.44 Fixing only 8.68 Very low fixing (1)

  3.5% copper octanoate, 0.5% amine and 95% chlorinated solvent.

  The control primer was used to coat the surfaces by

  before depositing the first part of the adhesive composition

of Example 1.

  (2) (2) All specimens for tensile shear were in

soft sanded steel.

M Pa M Pa

Claims (14)

  A two-part adhesive composition comprising (A) as a first part a resin system comprising (1) at least one polymerizable acrylate or methacrylate material;   (2) a radical polymerization initiator   calaire selected from peroxides, hydroperoxides, peresters, persalts and peracids; (3) optionally a sulfimide; and (4) optionally a hydrazine derivative; and (B) as a second part a resin system comprising (1) at least one polymerizable acrylate or methacrylate material; (2) a solventless accelerator system comprising a transition metal salt; and (3) optionally an amine co-accelerator with the transition metal salt,   the resin systems of each part being sensitive   given in viscosity and rheology.   A two-part adhesive composition according to claim 1, wherein the polymerizable material of one or both of the moieties is a mono-functional monomer and corresponds to the formula I CH 2 = C-COOR 2 R 1   wherein R is H, CH 3 or lower alkyl group R 23   R is H or an alkyl, alkoxy, cycloalkyl coyle or alkylene.   A polymerizable material according to claim   cation 2, wherein the mono-functional monomer is hydroxypropyl methacrylate, methacrylate   hydroxyethyl or tetrahydrofurfuryl methacrylate.   An adhesive composition according to claim   cation -1, in which the polymerizable material of   one or both parts is a poly-   functional and corresponds to the formula 1 R 3 3 5 R II R 5 (CH 2) m 5 p k   in which R 3 is H, an alkyl or hydroxyalkyl group   Coyle at C or R 5 OCH 2-; R 6 is H, a halogen or a 1-4 2 4 5 5   C 1-4 alkyl group; R is H, OH or R O-; R is CH 2 = CR 6 C = O; m is an integer of 1 to 8; k is a   integer from 1 to 20; and p is 0 or 1.   A polymerizable material according to claim   cation 4, wherein the polyfunctional monomer is   polyethylene glycol dimethacrylate, dimethacrylate   tetraethylene glycol crylate or dimethacrylate triethylene glycol.   A polymerizable material according to claim   cation 4, wherein the polyfunctional monomer is   dipropylene glycol dimethacrylate.   7 A two-part adhesive composition   according to claim 1, wherein the polymeric material   of one or both parties is a mono-   polymerizable acrylic ester parent represented by the formula: wherein R is selected from the group consisting of hydrogen, chlorine and methyl and ethyl radicals; R is a divalent organic radical selected from the group consisting of lower alkylene radicals of 1-8 carbon atoms, phenylene and naphthylene; W is a polyisocyanate radical; E is a   aromatic polyol or polyamine radical, heterocyclic   or cycloaliphatic, a diol of a cycloaliphatic compound   phatic; d is 1 or O; i is 0 when d is 0, and otherwise is one less than the number of atoms   hydrogen reagents of E; Z is (1) a radical of   poly (ethylene glycol) graft polymer or copolymer or (2) a methylene ether polymer polyol or copolymer radical; z is an integer equal to the valence of Z; an asterisk indicates a urethane (-NH-CO-O-) or ureide (-NH-CO-NH-) bond; or IV (A-X-CO NH- ±) B   X is -O or -R 9 N-; R 9 is selected from the group consisting of H and lower alkyl groups of 1 to 7 carbon atoms; A is CH 2 = CR 10 CO O-; R 1 is H or CH 3; N is an integer from 2 to 6 inclusive; and B is a polyvalent alkyl, alkenyl, cycloalkyl, aryl, aralkyl or alkoxyalkylene radical,   aryloxyarylene or heterocyclic, substituted or unsubstituted.   A two-part adhesive composition according to claim 1, wherein the polymerizable material of one or both of the parts is a polymerizable acrylic ester monomer represented by the formula: ## STR2 ## R 12 2   wherein R 1 is H, CH 3, C 2 H 5 or C 1; R 12 is a C 2-20 alkylene, alkenylene or cycloalkylene radical or a C 6-40 arylene, alkarylene, aralkarylene, alkyloxyalkylene or aryloxyarylene radical which may be substituted with 1-4 chlorine atoms or with 1-3 amino groups or mono- or di- (C 1-3 alkyl)   amino or C 1-3 alkoxy; R 13 is one of the following groups   less than one hydrogen atom; (a) a hydroxy group   C 1 -C 8 alkyl or aminoalkyl, (b) C 1-6 alkylamino C 1-8 alkyl group; or (c) a hydroxyphenyl, aminophenyl, hydroxynaphthyl or aminonaphthyl group which may be further substituted with an alkyl, alkylamino or dialkylamino group, wherein each alkyl group in the radicals indicated in (c) containing up to about 3 carbon atoms.   A two-part adhesive composition according to claim 1, wherein the polymerizable material of one or both of the parts is a polymerizable acrylic ester monomer having the formula: CH 3 (CH 3)   VI H = C (CH 3) COOC 3 H 6 OCOHN NHCO O 2 or (CH 2 C CH 3   VII H 2 = C (CH 3) COOCH 2 CH 2 OCONH NHCO O 3 PR   PR represents a residue of propylene triol oligomer.   A two-part adhesive composition   according to any of claims 2, 4, 7, 8 and   9, in which, in the first part, the radical polymerization initiator is cumene hydroperoxide, t-butyl perbenzoate or t-butyl peroctanoate. 11 A two-part adhesive composition   according to any one of claims 2, 4, 7, 8   and 9, wherein the transition metal salt is selected from the group consisting of copper naphthenate, copper ethylhexanoate and acetylacetonate of copper.   12 A two-part adhesive composition   according to any one of claims 2, 4, 7, 8   and 9, wherein the amine co-accelerator of the   second part is a tertiary aromatic amine.   13 A two-part adhesive composition   according to any one of claims 2, 4, 7, 8   and 9, wherein the sulfimide in the first group   is saccharin or a saccharin derivative.   14 A two-part adhesive composition   according to any one of claims 2, 4, 7, 8   and 9, wherein the hydrazine derivative of the first first part is of the formula: R 17-NH-NH-CO-R 18   wherein R 17 and R may be the same or different and are straight or branched C 1-6 alkyl, C 1-4 acyl radicals or C 1-4 aryl radicals.   A bonding method wherein (1) coating a first portion of a two-part adhesive composition on a first surface; (2) coating a second portion of a two-part adhesive on a second surface; (3) the two surfaces are in contact with each other   mutual benefit in the area covered by each party   of the adhesive composition, characterized in that said adhesive composition is as defined   in any one of claims 1 to 14.