FR2711373A1 - Coating composition comprising a monoacrylate - Google Patents

Abstract

The invention relates to a coating composition. This coating composition is a curable composition, and is preferably a UV curable coating composition and / or an anaerobic curing curable coating composition, suitable for the preparation of an adhesive, or 'anaerobic, UV-hardening sealant. The coating composition contains at least one acrylate.

Description

1 2711373

  The present invention relates to a coating composition. In particular, it relates to a curable coating composition that can be used as an adhesive, sealing compound, encapsulation product,

  protective coating, putty or the like.

  The present invention furthermore relates, in particular, to a UV-curable coating composition and / or an anaerobic curable coating composition, for example an anaerobic, UV curable adhesive or sealant, or the like. More particularly, the present invention relates to a method for rapidly bonding substrates, such as a metal part to other parts, to make a leak-proof seal, by using an anaerobic, water-hardening sealant composition. UV, in addition to the compositions themselves. Especially, the invention relates to a method for rapidly bonding a metal pipe to a metal panel so as to provide a leak-proof assembly, and in particular an aluminum pipe on an aluminum panel, such as a car radiator or

  another similar panel heat exchanger.

  In some industrial sectors, the substrates are coated (in whole or in part) with a coating composition. Of course, the nature of the composition of a coating depends on its use. For example, with coating compositions used as adhesives, it is sometimes desirable, or even necessary, for the coating composition to be able to form a bonded joint having a high adhesive force between two substrates, for example between two metal substrates, relatively quickly. , which are not necessarily the same metal, between a metal substrate and a substrate

2 2711373

  non-metallic such as glass, or between two non-metallic substrates, which are not necessarily of the same material (eg glass and rubber). If the coating composition is to be used as a sealing compound, it is likewise sometimes desirable, and even necessary, for the coating to be able to form a good seal fairly quickly. It is the same for coating compositions intended to be used as intermediate layers, that is to say to separate a

substrate of the other.

  With particular reference to adhesive coating compositions, it is known that the formation of a leak-proof seal between a metal conduit and a metal foil panel, such as is often required in the construction of metal heat exchangers (eg aluminum) or radiator panels for automobiles, can raise many problems. Particularly exemplary are the mass production lines, where it is vital that a fully watertight bonded joint be formed quickly between the pipe and the panel. In a representative method of forming such a bonded joint, one end of the pipe, in close fit, is inserted into a corresponding hole in the panel, welded to or bonded to it, for example by means of an anaerobic adhesive or sealing compound, which forms a large surface bead of the sealing compound along the joint line and between the facing surfaces. Although this type of assembly can provide a leak-resistant, strong bond between the panel and the pipe, the exposed bead of the anaerobic sealant around the assembly has a relatively slow cure, so that the formation of such an assembly lasts a long time and

  not suitable for a mass production line.

3 2711373

  In JP-A-57119970, Matsushita Electrical Industries KK discloses a method for attaching a rotor to a shaft, which comprises applying a UV curing anaerobic composition between the rotor and the shaft, hardening the outer bead of the anaerobic compositions. to form a leave, while allowing the composition to remain between the two pieces, to harden by anaerobic curing at room temperature or by means of heating. For this purpose, anaerobic curing methacrylic monomers ("acrylate" resins) are preferred. A preferred composition comprises from 20 to 70 parts by weight of a hydroxyalkyl methacrylate and from 70 to 70 parts by weight of an adduct of bisphenol-A and methacrylic acid, from 0.1 to 10 parts. by weight of a photosensitizer and optionally other minor components such as polymerization accelerators, inhibitors, dyes, tackifiers, etc. These compositions are said to have excellent adhesion and UV curing properties. Suitable photosensitizers include benzoin, acetophenone, and anthraquinone. However, there are some problems associated with the compositions of JP-A-57119970. From this point of view, these are essentially rigid curing compositions, which form a mechanical key between the rotor and the shaft, rather than a glued joint,

perfectly adhesive.

  These anaerobically rigid hardening UV curing compounds therefore have little value when it comes to situations in which a truly adhesive seal is required, ie, a bonded seal having a high peel strength, the

cleavage and shearing.

4 2711373

  There is therefore a need for a coating composition that can impart the characteristics

  desired in a short period of time.

  In particular, there is a need for a coating composition of this type, but which is a UV curable coating composition and / or

anaerobic curing.

  Especially, there is a need for a UV curable anaerobic adhesive composition, providing high resistance to peeling, cleaving and shearing, particularly to light alloys and metal alloys, and especially to non-rigid substrates such as than thin aluminum sheets. The present invention provides for this purpose a curable coating composition comprising a curable monomer and at least one polymerization initiator; the curable monomer being a monoacrylate of formula (I):

CH2 = CHCOOR (I)

  wherein R is an alkyl or cycloalkyl group having up to 20 carbon atoms, or an alkyl or cycloalkyl group having up to 20 carbon atoms whose carbon chain is interrupted by one or more atoms

of oxygen of ether (-O-).

  The present invention also provides a process for total or partial coating of a first substrate which comprises applying to the first substrate a composition according to the present invention, and exposing all or part of the coating to conditions allowing

  to initiate the polymerization of the composition.

2711373

  The present invention also provides a solid coating comprising a coating composition

  cured according to the present invention.

  Finally, the present invention also provides the use of a monoacrylate of formula (I) as a

  curable component of a coating composition.

  Optionally, the radical R in formula (I) may be an alkyl or cycloalkyl group having up to 20 carbon atoms and containing one or more substituents chosen from -OH, -CN, aryloxy radicals

(for example, phenoxy) and -NH2.

  Preferably, the at least one polymerization initiator is chosen from at least one of the polymerization initiators under the effect of radiation, the anaerobic polymerization initiators and the initiators of the polymerization process.

thermal polymerization.

  Preferably, the polymerization initiator or initiators are polymerization initiators under the effect of radiation and / or polymerization initiators.

anaerobic.

  Preferably, the at least one polymerization initiator is at least one polymerization initiator under the influence of radiation, preferably initiators of

photosensitive polymerization.

  Preferably, the polymerization initiator (s)

  are UV polymerization initiators.

  Accordingly, according to a first preferred aspect of the present invention, there is provided a UV curing coating composition comprising a UV curing monomer and a photosensitive polymerization initiator, the curing monomer being

  UV being a monoacrylate of formula (I).

  According to a second preferred aspect of the present invention, there is provided an anaerobic curable coating composition comprising a monomer

6 2711373

  curable by anaerobic curing and an anaerobic polymerization initiator, the anaerobically curing monomer being a monoacrylate of formula (I). According to a third preferred aspect of the present invention, there is provided a UV curing anaerobic adhesive coating composition comprising i) a monoacrylate of formula (I), ii) an anaerobic polymerization initiator (preferably a redox polymerization initiator anaerobic) and iii) a photosensitive initiator. According to a fourth preferred aspect of the present invention, there is provided a method for total or partial coating of a first substrate, which comprises applying to the first substrate a composition according to the first preferred aspect of the present invention and to exhibit all or part of the coating to a

UV radiation.

  According to a fifth preferred aspect of the present invention, there is provided a method of a total or partial coating of a first substrate, which comprises applying to the first substrate a composition according to the second preferred aspect of the present invention, and to submit all or part of the

  coating under anaerobic conditions.

  According to a sixth preferred aspect of the present invention, there is provided a method for forming an adhesive joint between a first substrate and a second substrate, which comprises applying between the substrates a UV curing anaerobic adhesive coating composition according to the third preferred aspect of the present invention, and to expose at least a portion of the adhesive coating so applied to UV radiation, so as to initiate the photochemical hardening of the adhesive, at least in the areas thereof that are exposed to

7 2711373

  radiation while leaving the rest of the composition

  applied undergo anaerobic curing.

  Preferably, the composition contains one or more other monomeric acrylates selected from the corresponding esters of acrylic acid or methacrylic acid, and the polyacrylates and polymethacrylates of acrylic or methacrylic acid and a polyhydric alcohol or

an ether-alcohol.

  Preferably, the monoacrylate is the acrylate of

butylcyclohexyl.

  Preferably, the composition contains an initiator of

free radicals.

  Preferably, the composition contains up to about% (preferably up to about 50%) by weight, based on the total composition, of a low molecular weight elastomeric polymer having a number average molecular weight of 1,000. and 6,000 and having one or more reactive groups in a lateral or terminal position on the molecule of the elastomeric polymer, the reactive groups being at least one of the following groups: -CH = CH2, -COOH, -SO2Cl, -SH, -NH2 and -OC (O) C (R) = CH 2, where R is H or a C 1 -C 4 alkyl radical or halo. Preferably, the method comprises forming an adhesive seal between a first substrate and a second substrate, the method of applying the adhesive coating composition between the surfaces facing the two substrates and in an amount sufficient to form an outer bead of uncured adhesive along the seam line, and exposing the outer bead of uncured adhesive to UV radiation so as to initiate photochemical curing of the bead, while allowing the adhesive to undergo anaerobic curing between facing surfaces.

8 2711373

  Preferably, the method relates to forming an adhesive seal between the end of a first tubular member snugly inserted into a hole of suitable size, provided in a second member, the outer bead of the uncured adhesive completely surrounding the tubular element along the line of seal, between it and the second element, so as to form a perfectly leak-proof adhesive joint between

  the first and second elements.

  Preferably, this method relates to the formation of a leak-proof adhesive joint between a tubular inlet or an outlet outlet of a heat exchange panel serving as a first element, the second element

  being a heat exchanger panel.

  Preferably, the heat exchanger panel is a radiator for the cooling circuit of a

motor vehicle.

  Alternatively, the composition of a coating may be applied to a substrate so that it flows into a channel or into a groove, or into a joint, prior to

to undergo a hardening.

  Preferably, the first substrate is a metal substrate. Preferably, the first substrate is a substrate in

aluminum.

  Alternatively, the process may involve forming an adhesive bond between two substrates, at least one of which is glass, or another material transparent to UV light, the photochemical curing of the adhesive, and applied being initiated by exposing the applied adhesive to UV radiation passing through the UV-transparent substrate. Preferably,

  the method relates to the formation of a glass-bonded joint

  glass, a glued metal-glass joint or a glued joint

glass-ceramic.

9 2711373

  The polymerizable monomer of the coating composition of the present invention is at least one monomeric acrylate, unlike the prior art monomeric methacrylate, especially that described in JP-A-57119970. The results achieved by the compositions of the present invention are particularly surprising. The main advantage of the present invention is that it provides a curing coating composition to give an excellent coating by exposing the composition to conditions that initiate polymerization of the composition, such as exposure to UV radiation and / or under anaerobic conditions. More specifically, the present invention makes it possible to provide a coating composition having a dual hardening possibility, more specifically a UV curing and

anaerobic curing.

  Among the other advantages of the present invention, it can be mentioned that it produces an adhesive having a high resistance to peeling, cleavage and shearing, in particular on light alloys and metal alloys and especially on non-rigid substrates such as that thin sheets

aluminum.

  Another important advantage is that the cured coating compositions are transparent. This means that the compositions of a coating can form an almost invisible seal between the two substrates. This fact is particularly advantageous in the construction of double glazing, where the composition of a coating is used to

  edges of a folded strip, for example aluminum.

  The present invention also provides an excellent seal or protection cover which

2711373

  can be used for example to cover a hinge or latch, to protect it from rust, etc. This is particularly advantageous in the automotive industry when it comes to applying a coating on bolts that connect a latch or

lock to a car hood.

  The present invention also provides an intermediate layer having excellent adhesion and / or sealing properties. This fact is particularly advantageous in the manufacture of bales and the like. In particular, the coating composition is particularly suitable for the preparation of strikers used in conjunction with seat belts in the automotive industry. From this point of view, the coating composition forms an intermediate layer between the striker and its envelope, so that the striker can easily leave the envelope when triggered, for example under

  the effect of a fast braking of the automobile.

  Other advantages will come out of the description

examples below.

  The term "coating composition" in the context of the present invention refers to any coating composition suitable for coating, in whole or in part, one or more substrates. The coating composition may be in liquid form or solid form, or in their intermediate forms, or combinations thereof. The coating combination can serve two or more purposes. For example, the coating composition may be used at least for an adhesive, a sealant or a protective interlayer. The coating composition can even be used as a coating or putty. The coating composition can even be used in encapsulating articles, such as electrical or mechanical articles. Articles can be articles

  delicate, for example pieces of jewelery.

  The term "curable", applied to the monomers of the present invention, indicates that the monomers can form polymers under appropriate curing conditions, depending on the choice of the polymerization initiator (s) in the coating composition, such as radiation (preferably UV light), exposure to heat or exposure to

anaerobic conditions.

  The term "radiation", in conjunction with the polymerization initiator, refers to any suitable polymerization initiator which is activated by appropriate spectral radiation. In particular, it includes photosensitive polymerization initiators. In particular, he

  denotes a UV polymerization initiator.

  The term "anaerobic", in conjunction with the polymerization initiator, refers to any suitable polymerization initiator that is activated by an almost complete absence

oxygen.

  The term "thermal", in conjunction with the polymerization initiator, refers to any suitable polymerization initiator capable of being activated by heat application or heat exposure, which may be from any suitable source or produced

by the latter.

  Thus, according to a particularly preferred embodiment of the present invention, there is provided an ultraviolet-curing anaerobic adhesive composition having a very high adhesion strength. The UV curable anaerobic compositions of the present invention are remarkable in that they retain their stability in the presence of air or oxygen, while hardening very fast (one to two seconds) after exposure to UV radiation and all keeping their

12 2711373

  ability to undergo anaerobic curing away from air or oxygen but without losing their curing speed. The coating compositions of the present invention preferably contain a low molecular weight reactive rubber. Examples of suitable low molecular weight rubber are described in GB-A-1505348 and GB-A-1550778. This rubber can give, for example, a multi-cure adhesive composition having the fast curing characteristics of a UV curing resin on the one hand while retaining the characteristics of an anaerobic adhesive on the other hand and giving after hardening a flexible adhesive composition, extremely tenacious, which can give flexible glued joints and having a high adhesion strength between substrates of all types, for example seals

  glued metal-metal, glass-metal, glass-glass, plastic-

  plastic, plastic-metal and plastic-glass. These compositions can therefore be used as adhesive

universal fast curing.

  A particularly preferred embodiment of the present invention is directed to a UV curing anaerobic adhesive comprising the following components, and preferably consisting essentially of these components: i) an anaerobic polymerizable polymerizable monomer system containing as main monomer component one or more monoacrylates of formula:

CH2 = CHCOOR

  wherein R is an alkyl or cycloalkyl group having up to 20 carbon atoms, optionally containing a

13 2711373

  or more substituents selected from the substituents -OH, -CN, aryloxy, for example phenoxy and -NH2, or an alkyl or cycloalkyl group having up to 20 carbon atoms whose carbon chain is interrupted by one or more atoms of ether oxygen (-O-); and as optional secondary constituent, one or more monomeric acrylates as defined above, selected from the corresponding esters of acrylic acid or methacrylic acid, polyacrylates and polymethacrylates of acrylic or methacrylic acid and a polyhydric alcohol or an alcohol ether, and acrylic acid or methacrylic acid; ii) an anaerobic redox polymerization initiator system; iii) a photosensitive initiator system; and iv) from 0 to 60 (preferably up to 50%) by weight, based on the total composition, of a low molecular weight elastomeric polymer having a number average molecular weight of from 1000 to 6000 and having a or more reactive groups in a lateral or terminal position on the molecule of the elastomeric polymer, these reactive groups being chosen from the radicals --CH = CH2, -COOH, -SO2Cl, -SH, -NH2 and the groups of formula - OC (O) C (R) = CH2, where R is H or an alkyl radical

C1 to C4 or halo.

  Another particularly preferred embodiment of the present invention is a method of adhesively adhering a first member to a second member to form a leak-proof adhesive seal between the two members, which comprises applying

  an anaerobic UV curing adhesive as defined herein.

  above, between the surfaces facing the parts to be assembled and in the form of an adhesive external bead along the lines of the joint, exposing the uncured adhesive outer bead to UV radiation to initiate a

14 2711373

  UV curing the outer bead of adhesive while allowing the anaerobic adhesive to undergo anaerobic curing within the seal and between the facing surfaces, this operation being, if desired, assisted by the application of heat. Another preferred embodiment of the present invention relates to a method of adhesively bonding a metal pipe, for example aluminum, to a metal panel, for example an automobile radiator or a heat exchange panel, for forming a leak-tight adhesive bonding therebetween, and which comprises the steps of inserting an end of the metal conduit in a tight fit into a hole in the panel, to be applied to the bonded joint, an anaerobic UV-curing adhesive, such as as defined above, in an amount sufficient to penetrate between facing surfaces and to form a continuous outer bead of uncured sealant around the seam, and to expose the uncured outer bead of adhesive to UV radiation to initiate external cord hardening while allowing the adhesive to undergo anaerobic curing within the gasket olled between the surfaces

opposite.

  While the preferred methods described above are particularly concerned with the formation of a leak-proof bonded joint between two members and, for this purpose, use an amount of the anaerobic composition sufficient to form an external bead of adhesive uncured along the seam line, this cord being then exposed to UV radiation to initiate curing of the outer bead, the internal curing being performed anaerobically, the anaerobic adhesives of the present invention are useful through the assembly fast other joints in which a

2711373

  absolutely leak-proof bonding is not of fundamental importance. These adhesives can also be used in certain situations where a UV curing adhesive is needed. A situation of this type is, for example, the formation of glued glass-glass, glass-metal or glass-ceramic joints, such as those which

  are usually used in the field of semi-

  conductors and optical fibers and o, after application of the adhesive between two facing surfaces, the hardening of the applied adhesive layer undergoes a photochemical initiation under the effect of a radiation of the assembly with the aid of a UV light. With this technique and with the UV curing anaerobic adhesives of the present invention, it can be formed in one to two seconds,

  or less, glued flexible joints, resistant, glass-

  glass, glass-metal, or glass-ceramic.

  As has been said, the monomer component of the compositions of the present invention is at least one monoacrylate of the formula:

CH2 = CH - C (O) - O - R

  in which R is an alkyl or cycloalkyl group having up to 20 carbon atoms, optionally containing one or more substituents selected from -OH, -CN, aryloxy radicals, for example phenoxy, -NH2 and oxygen ether - O- or mixtures of at least two of them. Among the monoacrylates which may be used which are preferred, mention may be made, for example, of methyl acrylate, ethyl acrylate and cyclohexyl acrylate.

  tert-butyl-cyclohexyl acrylate, acrylate 2-

  hydroxyethyl, 2-cyanoethyl acrylate, acrylate

  tetrahydrofurfuryl and phenoxyethyl acrylate.

16 2711373

  At least two acrylates, and especially a mixture of a monoacrylate and a polyacrylate, are usually used. These mixtures also often contain a small amount of acrylic acid or methacrylic acid as an additional monomer. Polyacrylate and monoacrylate may be typical acrylates used in anaerobic adhesives, and may also be

  used in the compositions of the present invention. Examples of suitable monomers can be found in the numerous

  prior patents and published patent applications relating to anaerobic adhesives, the following publications of which are representative:

  GB-A-1151916, GB-A-1347068, GB-A-1374351, GB-A-137535,

  GB-A-1505348, GB-A-1550748 and GB-A-1550778.

  Suitable polyacrylates include, for example, ethylene glycol diacrylate, diethylene glycol diacrylate, neopentyl diacrylate, and

  1,1,1-trimethylol propane triacrylate.

  As previously mentioned, acrylate-based anaerobic adhesives generally contain one or more catalysts, activators and inhibitors, in admixture with the acrylates to impart the anaerobic curing properties. Likewise, the compositions of the present invention also generally contain one or more

  of these catalysts, activators and inhibitors.

  The polymerization initiators used in the compositions of the present invention may be

known known initiators.

  For example, to achieve the characteristic UV curing aspect of the present invention, the coating compositions of the present invention contain a photoinitiator, usually in an amount of 1 to 10 and more usually 2 to 3% by weight. weight

  relative to the total composition.

17 2711373

  Preferably, the photoinitiator is of the free radical type and it is for example those marketed under the trademark IRGACURE, for example 2,2-dimethoxy-1,2-diphenylethane-1-one (Irgacure 651) or 1-hydroxycyclohexylphenylketone, or other analogous compounds. However, equally good results are obtained with cationic photoinitiators, for example with

triaryl sulfonium salts.

  The photoinitiator can be incorporated into the coating composition at any time, but it is preferably added after mixing the monomers

  and the optional reactive elastomer.

  The catalysts that may be present in the compositions of the present invention may be any of the catalysts commonly used in the art. For example, tertiary amines and compounds containing a -CO-N <group may be used. Among their representative examples, mention may be made of N, N-dimethyl-p-toluidine,

  tri-n-butylamine, 2-diethylaminoethanol, N-

  methylformamide, phthalimide, succinimide, ortho-

  benzo-sulfimide and dodecylmercaptan. As activators, a compound capable of forming free radicals is used directly or indirectly, these compounds typically comprising peroxide compounds, for example peroxides, hydroperoxides and peresters, such as cyclohexylhydroxycyclohexyl peroxide,

  tert-butyl hydroperoxide, tert-butyl perbenzoate

  butyl, hydrogen peroxide, cumene hydroperoxide, hydroperoxide ethylene dimethyl ether

  glycol and 2,5-dimethyl-2,5-di (t-butylperoxy) hexane.

  Inhibitors that can be used in the coating compositions of the present invention

18 2711373

  include naphthoquinone, hydroquinones,

  hindered phenols and nitroxides.

  Other additives such as accelerators, viscosity modifiers, fillers, tackifiers, adhesion promoters, and other additives may also be incorporated in the anaerobic curing composition as is customary.

dyes and plasticizers.

  The formulation and / or treatment of the coating composition to achieve the desired anaerobic cure properties, are in accordance with principles and techniques well-established in the art, such as, for example, a passage of air or oxygen through the mixture containing the monomer ester or the monomer ester mixture, the catalyst, the activator or the inhibitor, until a stable composition is obtained which is capable of undergoing

anaerobic curing.

  The term "stable" as used herein refers to a composition which, when heated to about 82 ° C or about 100 ° C, will not gel respectively in

30 minutes or 300 seconds.

  In certain formulations, which use certain combinations of a catalyst and / or an activator and / or an inhibitor, the necessary stabilization can be achieved without the need for oxygenation, as is known in the art. technical. However, when formulating the preferred anaerobic curing compositions according to the present invention which contain a reactive elastomer, it is an oxygen or air oxygenation which represents the preferred treatment of

stabilization.

  The low molecular weight elastomers that are

  preferably incorporated into multi-media compositions.

  curing of the present invention, to impart to the cured composition improved properties of impact resistance, peel strength and

19 2711373

  shearing, are low molecular weight elastomers containing at least one active group attached to the polymer molecule, this reactive group having the formula -NH2, -SH, -COOH, OSO2C1 or -OC (O) C (R) = CH2, R is as defined above, that is to say H or a C1-C4 alkyl or halo, preferably a hydrogen. The reactive elastomers used in the present invention are rubbers which are soluble in the acrylate component of the anaerobic curing composition. Liquid elastomers having a number-average molecular weight of between 1000 and 6000 are preferred

  and especially between 2500 and 5000.

  The preferred low molecular weight polymers have a framework consisting of polymerized butadiene units, optionally with a certain proportion of units.

polymerized acrylonitrile.

  Butadiene and butadiene-acrylonitrile copolymer, esters of acrylic acid or 2-alkyl-substituted acrylic acids having a number-average molecular weight of between 3,000 and 4,000 and polyethylene chlorosulfones are most particularly preferred.

  (HYPALON) including their variants.

  Representative examples of these butadiene and butadiene / acrylonitrile copolymers are

  acrylate termination those marketed by B.F.

  Goodrich Chemical Co., under their trademark Hycar, namely Hycar VTB and VTBN, which are respectively a vinyl-terminated butadiene and a vinyl-terminated butadiene / acrylonitrile polymer whose average molecular weight is

  number is between 3000 and 6000.

  Examples which are closely related to the above compounds are vinyl-terminated butadiene / acrylonitrile copolymers containing a terminal or terminal vinyl group and marketed under

  the Hycar VTBNX brand, which are particularly preferred.

2711373

  Other elastomeric and low molecular weight reactive liquid elastomers which can be used in the present invention include: Hycar MTBN (butadiene / mercapto-terminated acrylonitrile), number average molecular weight 3270, acrylonitrile content 19.4%; and Hycar ATBN (butadiene / acrylonitrile amino terminated). In addition to the carboxy, amino, vinyl and mercapto-terminated butadiene / butadiene / acrylonitrile polymers mentioned above, other examples include the low molecular weight reactive elastomers which can be used in the present invention. urethanized polybutadienes and halogenated polybutadienes, for example, brominated polybutadiene, butadiene and styrene copolymers, polyisoprenes and polychloroisoprenes, all of which contain one or more reactive groups as specified above. It is also possible to use low molecular weight chlorosulfonated polyolefins,

  for example a chlorosulphonated polyethylene (HYPALON).

  The low molecular weight reactive elastomers are preferably incorporated in the composition in an amount of up to about 60% (eg 1 to about 60% and preferably about 50%) by weight based on the total composition. . They may be incorporated into the anaerobic curing composition at any time during mixing or stabilizing operations. In the preferred technique, an anaerobic curing composition is first prepared by oxygenating a mixture of the acrylate containing the necessary activators, catalysts and inhibitors by adding the liquid reactive elastomer to the oxygenated mixture and continuing the oxygenation. until the

21 2711373

  final mixture has a gel time of 100 OC

not less than 300 seconds.

  In order to provide the particularly preferred coating compositions of the present invention with the characteristic multi-cure functionality, a photoinitiator can be incorporated into an anaerobic composition of the present invention at any time. But the addition is preferably made to the stabilized anaerobic adhesive, after mixing the monomers with the constituents of the initiator system and the elastomer

  reagent, and after oxygenation of the mixture.

  The following examples show anaerobic UV curable adhesives, which are representative and

preferred according to the invention.

EXAMPLE I

  Anaerobic formulation% by weight t-butylcyclohexyl acrylate 57.9 HYCAR VTBNX2 (1300 x 33) 25.0 acrylic acid 9.0 trifunctional oligoacrylate3 2.0 saccharin 1.0 cumene hydrate 2.0 1,4 1,4-naphthoquinone 4 0, 2 tetrasodium EDTA 0.6 N, N-dimethyl-p-toluidine 6 0.3 2,2-dimethoxy-1,2-diphenylethan-1-one 2.0 Notes: 1 IRR 164 (Trade Mark) marketed by UCB 2 Oligomer methacrylate-functional butadiene-acrylonitrile sold by BF Goodrich (HYCAR VTBNX is a registered trademark) 3 EBCRYL 48 (trade mark), marketed by UCB

22 2711373

  4 In 5% solution in triethylene glycol dimethacrylate In 5% solution in a 1: 1 mixture of water and isopropanol 6 NL65 / 100 (registered trademark), marketed by Akzo Chemie 7 IRGACURE 651 (registered trademark) , sold by Ciba-Geigy The monomer components, in particular the HYCAR VTBNX low molecular weight elastomer, are mixed with the constituents of the initiator and oxygenated system essentially according to the general procedure described in Example 1 of GB-A-1505348. to give a

  initial anaerobic formulation, shock resistant.

  In more detail, the steps of the procedure are as follows: 1. In the quantities indicated above, in a glass flask fitted with a non-metallic stirrer, t-butylcyclohexyl acrylate, the

  trifunctional oligoacrylate, 1,4-

  naphthoquinone and tetrasodium EDTA; 2. then HYCAR VTBNX is added in the amount indicated above; 3. then the saccharin is added in the amount indicated above, and allowed to dissolve; 4. then cumene hydroperoxide is added in the amount indicated above; 5. then the mixture obtained is aerated for about 15 minutes;

  6. Then add in increments the N, N-dimethyl-p-

  toluidine until the total amount added is equal to the amount indicated above; 7. The mixture is then subjected to a stability test at 100 ° C for 300 seconds;

23 2711373

  8. then 2,2-dimethoxy-1,2-diphenylethan-1-one (i.e. photoinitiator) is added in the amount indicated above; 9. The mixture is then subjected to a stability test at 100 ° C. for 300 seconds. The composition obtained is a liquid which, when it is confined in the form of a thin film between two substrates, hardens rapidly to give a solid polymer which adhesively adheres the two substrates, one to

the other.

  The standard stability test under anaerobic conditions is used at 82 ° C., and the composition has a gel time greater than 1 hour. The industry standard for anaerobic conditions requires a gel time, under these conditions, greater than 30 minutes. When tested on a degreased mild steel M8 nut and bolt, the composition gives a dry curing time of 10 minutes. After one hour at 25 ° C., the composition exhibits a resistance to torque

  1.3 Nm, which increases to 2.6 Nm after two hours.

  The ability of the composition to provide rapid curing after exposure to UV radiation is monitored using a UV Blue Point lamp (19.5 mW cm-2, 365 nm), on various test pieces having a glass bond -glass, glass-mild steel and glass-aluminum. In each case, the duration of the manipulation is 1 second or less, and the strength

  final adhesion is excellent in all cases.

  The flexibility of the UV-cured composition is checked on a sample comprising a polyester film bonded with the above composition to abraded aluminum, and cured for one second with the UV Blue Point lamp (19.5 mW). cm-2, 365 nm). Then the substrates are flexed to 180 without any

24 2711373

  loss of adhesion, and without any cracking of the adhesive. The multi-cure composition has a remarkable combination of properties: long-term stability (the test compositions are still liquid after one month storage under ambient conditions at C), excellent adhesion strength when used in the form of an anaerobic adhesive, with anaerobic curing times (curing 10 min. to the "touch" state) while giving excellent properties as a UV-curing adhesive, curing times being only by 1 second, and giving flexible joints, stubborn, high adhesion strength, between many different substrates, for example glass-glass, glass-metal, metal-plastic or glass-plastic.

  Each of the above results is surprising.

EXAMPLE II

  The procedure described in Example I is repeated to formulate an anaerobic adhesive containing the following constituents:% by weight Hycar VTBNX (1300 x 33) 24,27 t-butylcyclohexyl acrylate 38,91 isobornyl acrylate 9,70 Acticryl CL 10391 9.70 trimethylol propane trimethacrylate 3.89 acrylic acid 8.73 cumene hydroperoxide 1.89 Irgacure 1842 3.00 Notes: 1 Acticryl CL1039 (Trade Mark) is an acrylate marketed by SNPE or Harcros Chemicals Ltd. ; an equivalent of this product is the Genomer M 200 (brand

  filed) marketed by Rahn AG.

2711373

  2-hydroxy-cyclohexyl-phenylketone, marketed by

  Ciba-Geigy (Irgacure is a registered trademark).

  The above composition is used to glue the end of an aluminum tube into a hole having a corresponding diameter arranged in an aluminum panel, by inserting the end of the tube, after degreasing, into the hole formed in the panel, by applying the liquid sealant composition around the seal in an amount sufficient to penetrate the seal by capillary attraction, while leaving a continuous bead of uncured adhesive extending outward along the seal, and exposing the outer bead of uncured adhesive to UV radiation from a UV lamp. A durable, unbreakable bonded seam is made in seconds. In order for the bonded joint to exhibit maximum adhesive strength, the assembly is heated for 20 minutes at 100 ° C. The seal is perfectly watertight, even after immersion in a 50:50 mixture by volume of water. and

  ethylene glycol at the boiling point for 48 hours.

  The remarkable tightness of the leak-tight seal and its resistance to immersion in aqueous boiling point ethylene glycol (antifreeze) mixtures coupled with the fast curing characteristics of the anaerobic sealing compositions clearly demonstrate the utility composition in the manufacture of glued radiators or glued heat exchange panels, for example in the manufacture of radiators used in the automotive industry, in particular, because a glued joint with a high degree of leakage resistance, in a few seconds, with only minimal preparation of the facing surfaces, so that it is usually sufficient to degrease the facing surfaces before bonding, without

26 2711373

  that you have to do some other treatment,

  for example to remove oxide scale.

  To measure the effective adhesive strength of the cured adhesive, the same adhesive is used to bond a 12.025 mm diameter steel key into a 12.05 mm diameter hole (0.025 to 0.05 mm clearance) in a soft steel collar, the two facing surfaces having a surface finish of 0.4 to 0.5 μm. The adhesive is injected between the facing surfaces leaving an uncured adhesive fillet around the key. This fade was exposed for 20 seconds to UV light from a UV lamp having an intensity of 1814 pW at 365 nm, and the assembled parts were heated at 100 ° C. for 20 minutes to ensure accelerated and complete cure of the UV light. 'adhesive. After cooling to 23 ° C., the adhesion strength of the bonded joint is measured on a tensometer JJ, model TK30, the separation speed of the jaws being 6 mm.mn = 1. The maximum adhesion strength of the bonded joint obtained in the different samples studied is

27.0 MPa.

  Each of these results is surprising.

  Of course, the invention is not limited to the embodiments described above, and shown, from which we can provide other modes and other embodiments, without departing from the

framework of the invention.

2711373

Claims (26)

  A curable coating composition comprising a curable monomer and at least one polymerization initiator, characterized in that the curable monomer is a monoacrylate of formula (I): CH2 = CHCOOR (I)   wherein R is an alkyl or cycloalkyl group having up to 20 carbon atoms, or an alkyl or cycloalkyl group having up to 20 carbon atoms whose carbon chain is interrupted by one or more atoms of oxygen of ether (-O-).   2. Composition according to claim 1, characterized in that said at least one polymerization initiator is at least chosen from: a polymerization initiator under the effect of radiation, a polymerization initiator   anaerobic and a thermal polymerization initiator.   3. Composition according to claim 2, characterized in that said at least one polymerization initiator is at least one polymerization initiator under the effect of a   radiation and / or an anaerobic polymerization initiator.   4. Composition according to claim 3, characterized in that said at least one polymerization initiator is at least one polymerization initiator under the effect of radiation, that is to say a photosensitive polymerization initiator. 5. Composition according to claim 4, characterized in that said at least one polymerization initiator is   a UV polymerization initiator.   The composition of claim 1, characterized in that it is a UV curing anaerobic adhesive coating composition comprising: 28 2711373   i) a monoacrylate of formula (I) as defined in claim 1; ii) an anaerobic redox polymerization initiator; and iii) a photosensitive initiator. 7. Composition according to any one of   Claims 1 to 6, characterized in that the   composition contains one or more other monomeric acrylates selected from the corresponding esters of acrylic acid, methacrylic acid, or methacrylates and polyacrylates of acrylic acid or methacrylic acid and a polyalcohol or of an ether alcohol. 8. Composition according to any one of   Claims 1 to 7, characterized in that it contains   up to about 60% by weight, based on the total composition, of a low molecular weight elastomeric polymer having a number average molecular weight of between 1000 and 6000 and having one or more reactive groups in a lateral or terminal position on the molecule of the elastomeric polymer, these reactive groups being chosen from the radicals -CH = CH2, -COOH, -SO2Cl, -SH, -NH2 and the groups of formula -OC (O) C (R) = CH2, where R is H or a C1 to C4 alkyl radical or halo.   9. Composition according to any one of   Claims 1 to 8, characterized in that the   monoacrylate is t-butylcyclohexyl acrylate.   10. Composition according to any one of   Claims 1 to 9, characterized in that it contains   a photoinitiator, the latter being of the free radical type. 11. A process for total or partial coating of a first substrate, characterized in that it consists in applying to the first substrate a composition according to the 29 2711373   claim 1 or any one of claims 2 to   and exposing all or part of the coating to conditions for initiating polymerization of the composition. 12. Process according to claim 11, characterized in that the composition contains at least one UV polymerization initiator, the process of exposing   all or part of the coating to UV radiation.   13. The method of claim 11, characterized in that the composition contains at least one anaerobic polymerization initiator, the method of subjecting all or part of the coating to anaerobic conditions. A method for forming an adhesive bonded bond between a first substrate and a second substrate, characterized in that it comprises applying between the substrates a UV curing anaerobic adhesive coating composition according to claim 6 or any of   claims 7 to 10, and exposing at least a portion of the   adhesive coating applied to UV radiation, so as to initiate the photochemical hardening of the adhesive, at least in those areas which are exposed to the radiation, while allowing to cure under anaerobic conditions. rest of the composition applied.   15. The method of claim 14, characterized in that it consists in forming an adhesive bonded joint between a first substrate and a second substrate, to apply the adhesive coating composition between the surfaces opposite the two substrates and in a sufficient amount to form an uncured adhesive outer bead along the seam line and exposing the uncured adhesive outer bead to UV radiation to initiate photochemical curing of the bead, while allowing the adhesive to harden under anaerobic conditions; the facing surfaces. 2711373   The method of claim 14 or 15, as applied to the formation of an adhesive seal between the end of a first tubular member inserted into a tight fit into a hole of appropriate size arranged in a second member, and wherein the outer bead of uncured adhesive completely surrounds the tubular member along the line of seam between this member and the second member, to form a fully leak-tight adhesive bonded joint between the first and second members; the second elements.   The method of claim 16, as applied to the formation of a leak-tight adhesive seal between a tubular inlet or an outlet connector of a heat exchange panel serving as a first element, and a panel of heat exchange serving as a second element.   18. The method of claim 17, characterized in that the heat exchange panel is a radiator   for the cooling circuit of a motor vehicle.   19. Process according to any one of the claims   11 to 18, characterized in that the first substrate is a metal substrate.   20. The method of claim 19, characterized in   that the first substrate is an aluminum substrate.   21. The method of claim 11, as applied to the formation of an adhesive seal between two substrates, at least one of which is made of glass, or another material transparent to UV light, and wherein the photochemical hardening of the applied adhesive is initiated by exposing the applied adhesive to a   UV radiation through the UV-transparent substrate.   22. The method of claim 21, as applied to the formation of a glass-glass joint, a   glass-to-metal joint or glass-ceramic joint.   A solid coating comprising a solid coating composition according to claim 1 or   any of claims 2 to 10.   24. Use of a monoacrylate of formula (I) as defined in claim 1, as   curable component of a coating composition.   25. Use of a monoacrylate of formula (I) as defined in claim 1 as a UV curing component and / or anaerobically curing component of a composition coating.   26. Use of a monoacrylate of formula (I) as defined in claim 1, both as a UV curable component and as an anaerobically hardenable component of a composition coating.