CN101652446A - Composition for structural adhesives - Google Patents

Abstract

The present invention relates to compositions for acrylic structural adhesives comprising a mixture of block copolymers, elastomers and elastomeric polymer particles.

Description

Compositions for structural adhesives

The present invention relates to the field of acrylic structural adhesives (based on acrylates or methacrylates) and their use.

Structural adhesives are a good alternative to other mechanical techniques that join two materials together, such as metal or plastic. This is because bonding can result in better force distribution than when using other techniques such as riveting or welding. Furthermore, the use of gluing often allows faster work, also having the advantage of providing better isolation from external elements (dust, moisture) compared to mechanical techniques.

Consequently, structural adhesives are used in many industrial fields, although they do have certain disadvantages. In fact, the bond produced during the curing (setting) of the adhesive is often rigid when good mechanical strength is necessary. Thus, if the adhesive is not sufficiently elastic, fractures may be observed when the two parts to be joined together are subjected to a force that separates them. Adhesives with good elasticity do exist, but they often have low mechanical strength.

Therefore, there is a need to find structural adhesives that have both good mechanical strength (especially shear strength) and satisfactory elasticity. Furthermore, it is important to observe these properties in different types of materials, especially in metals and composites. Finally, it is important that these adhesives have a high viscosity to enable application of great lengths on vertical or overhanging surfaces without slipping or flowing off prior to application to the second surface to be adhered. This phenomenon is particularly annoying when long working hours are necessary.

This sliding phenomenon reduces the usefulness of, for example, acrylic-based adhesives in applications where long items need to be adhered to panels. The fact that attempts to use these adhesives can increase build time or complicate the manufacturing process.

Developing adhesives for such applications would make it possible to simplify the methods that require bonding two large areas, change the materials of construction, and speed up these methods.

It is an object of the present invention to solve the above problems by providing an adhesive composition that can be used in structural adhesives having an elongation at break equal to or greater than 80%, an tensile shear strength. Furthermore, the adhesive according to the invention has rheological properties which make it possible to apply the adhesive according to the invention to a smooth vertical metal surface with a thickness of at least 3-5 mm, preferably at least 6-8 mm, and upon polymerization Or said adhesive flow under the influence of gravity does not occur until the end of curing.

The adhesive according to the invention consists of the composition according to the invention and a second component comprising a polymerization initiator (catalyst). Compositions according to the invention were mixed with the second component on a vertical surface, a maximum thickness was observed at which gravity did not cause the adhesive to collapse before curing.

In general, the present invention enables the rheology of the structural adhesive to be adjusted while maintaining a minimum elongation of 80%.

Structural adhesives consist of two components, a catalyst used to polymerize or cure the other component containing monomers.

Accordingly, the present invention relates to compositions useful in structural adhesives comprising:

(a) at least one methacrylate monomer;

(b) at least one elastomeric block copolymer comprising styrene and at least one second monomer;

(c) at least one elastomer selected in such a way that its Hildebrand solubility parameter is compatible with that of the block copolymer used; and

(d) Particles formed from a thermoplastic shell and an elastic core.

Therefore, the composition according to the invention will be used together with a curing catalyst.

Preferably, the block copolymer (b) is selected from block copolymers comprising styrene and isoprene, elastomeric block copolymers comprising styrene and butadiene or ethylene or mixtures thereof.

In a preferred embodiment, the ester monomer (a) is a methacrylate monomer. It is preferred to select methacrylate monomers with short linear chains (ie, with one or two carbon atoms) in the alcohol moiety. Preferred monomers according to the invention are therefore methyl methacrylate and ethyl methacrylate.

In another specific embodiment, the alcohol moiety has at least one ring, which may or may not be substituted. Thus, in this particular embodiment, the monomers may in particular be selected from tetrahydrofurfuryl methacrylate, phenoxyethyl methacrylate, isobornyl methacrylate, glycidyl ether methacrylate, methyl benzyl acrylate, cyclohexyl methacrylate or trimethylcyclohexyl methacrylate.

Mixtures of these esters may also be used. The weight percentage of methacrylate in the composition is preferably 20-80%, more preferably 30-65%, even more preferably 42-58%, ie about 50%.

In a particular embodiment, the composition also comprises at least one linear acrylate monomer (e) (long-chain monomer) having an alcohol moiety of at least 6 carbon atoms. Preference is therefore given to using lauryl methacrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, esters based on polyethylene glycol or mixtures of these esters. The composition preferably comprises at most 10%, preferably at most 8% or even at most 5% of the total weight of these acrylic long chain monomers. In a particular embodiment, the composition comprises a mixture of two long chain acrylate monomers. Preferably, when the composition includes only one acrylate monomer (e), it is preferred that this monomer is present in an amount of 8% by weight or less, although when the composition includes a mixture of these esters (e), it is acceptable The amount is 8-10%. In this case it is preferred that each ester is present in an amount of up to 5%.

The composition may also include other monomers such as acrylonitrile, methacrylonitrile or styrene.

The compositions according to the invention also comprise one or more different block copolymers. Thus, it may comprise styrene-isoprene-styrene block copolymers (SIS), block polymers comprising styrene and butadiene or ethylene or mixtures thereof.

When the composition includes a block copolymer comprising styrene and butadiene, it may be styrene-butadiene-styrene (SBS) or styrene/isoprene-butadiene/styrene Copolymer (SIBS), such as Kraton MD6455 (from the company Kraton Polymers), which was presented by Dr. Donn DuBois et al. at the meeting "Adhesives & Sealants Committee Meeting (Adhesives & Sealants Committee Meeting", Louisville, KY, October 9-12, 2005). Sealants Council Meeting)” described.

When the composition includes a block polymer comprising styrene and ethylene, it can be SEBS (styrene/ethylene-butadiene/styrene copolymer) or SEPS (styrene/ethylene-propylene/styrene copolymer) . These compounds are available from Kraton G range (from Kraton Polymers).

Preferably, styrene is present in a proportion of 15-50%, more preferably 22-40%, even more preferably about 28-33% by weight of the SBS copolymer. It is present in the SIS or SIBS copolymer at a weight ratio of 12-24%, more preferably about 18-19%.

When the composition comprises a mixture of two block copolymers such as SIS and SIBS, the relative SIS/SIBS ratio preferably varies from a ratio of 4/1 (by weight of the composition) to 1.5/1. A preferred ratio of SIS to the second block copolymer is about 3/1 or 3.3/1. However, it is also possible to use SIS/SIBS mixtures in the same relative proportions as SIS/SIBS mixtures. It is also possible to use mixtures of SIS, SIBS and SBS. Another block copolymer may also be added to one of these mixtures.

The block copolymers SIS, SBS or SIBS which can be used according to the invention are known to those skilled in the art. In particular, they are produced by Kraton Polymers (Houston, Texas, USA). Thus, it is possible to use SIS Kraton D1160 or Kraton D1161 disclosed in US 20050238603, SBS Kraton D1102 and SIBS Kraton MD6455 or Kraton MD 6460 described in US 5106917.

A person skilled in the art knows how to select other SIS, SIBS and SBS block copolymers which can be used in the composition according to the invention from those which exist, in particular according to their solubility in the monomers used or according to their tensile strength thing.

Preferably, the composition according to the invention comprises 5-30%, preferably 12-25%, more preferably 15-25% by weight of the elastomeric block copolymer.

In a particular embodiment, the composition according to the invention comprises an elastomeric block copolymer comprising styrene and isoprene and at least one elastomeric block copolymer comprising styrene and butadiene, namely SIS /SIBS blend, SIS/SBS blend or SIS/SIBS/SBS blend.

In another particular embodiment, the composition according to the invention comprises only one elastomeric block copolymer comprising styrene and isoprene, ie SIS.

According to another particular embodiment, the composition according to the invention comprises only one elastomeric block copolymer comprising styrene and butadiene selected from SIBS or SBS.

The composition according to the invention also comprises at least one elastomer, chosen in such a way that it is compatible in solution with the block copolymer used. If necessary, it is functionalized (has a double bond at its end, especially a methacrylate function to improve binding to the monomer). Preferably, a liquid elastomer is chosen. Preference is given to using at least one functionalized elastomer alone or in admixture with at least one nonfunctionalized elastomer.

In particular, the elastomer is chosen in such a way that its Hildebrand solubility parameter is compatible with that of the block copolymer used. The Hildebrand solubility parameter is well known and is calculated from the square root of the cohesive energy density of the compound. In particular, the elastomer has a Hildebrand solubility parameter of 8-9. Therefore, it is preferred to use elastomers of the polybutadiene type (polybutadiene is preferably liquid and functionalized, for example with vinyl end groups, containing ester groups, such as those available from Emerald Performance Materials (EPM), (Cuyahoga Falls, Ohio , USA) Hycar VTB 2000x168 or Ricacryl 3801 from Sartomer) or polyisoprene type. Polychloroprene (Neoprene AD10 from DuPont, USA) can also be used. These elastomers can be used alone or in mixtures (thus, in particular, it is possible to use polychloroprene/(functionalized polybutadiene) blends or (functionalized polybutadiene)/(nonfunctionalized polybutadiene) Butadiene such as Hycar CTB 2000x162 (EPM)) mixture.

This component (c) is advantageously present in an amount of 4-20%, preferably 6-15%, more preferably about 8-12% by weight of the composition according to the invention.

In the composition, the relative weight ratio of the block copolymer/elastomer mixture is from 4/1 to 0.5/1, preferably about 2/1. However, it is also possible to have a relative ratio of about 0.5/1 order.

The compositions according to the invention also comprise elastomeric polymer particles. These particles, known in English as "core-shell" particles, are well known to those skilled in the art and consist of a "hard" thermoplastic shell, preferably based on polymethylmethacrylate (PMMA) and Formed from an elastic core, usually butadiene-based, often copolymerized with styrene, or acrylic-based. For the practice of the invention, particular mention is made of acrylonitrile-butadiene-styrene (ABS), methacrylate-butadiene-styrene (MBS) and methacrylate-acrylonitrile-butadiene-benzene Ethylene (MABS) polymers and their mixtures.

These particles consist of a crosslinked elastic core surrounded by a thermoplastic shell, often methyl-methacrylate polymer (PMMA). Patents US 3 985 703, US 4 304 709, US 6 433 091, EP 1 256 615 and US 6 869 497 describe such particles in particular and are therefore well known to those skilled in the art.

In particular, impact modified particles are preferred, especially MBS impact modifiers. In preferred embodiments, these MBSs have slight crosslinking of the polymers forming the core. Furthermore, these MBS, in addition to their impact strength, also preferably have shock-induced crack resistance.

Core-shell polymers are available from a number of companies. Accordingly, GEPlastics and Arkema (Paris, France) are also mentioned. Particularly preferred particles are Clearstrength C301, C303H, C223, C350, C351, E920 or C859 types, preferably C301 and C303H MBS, from Arkema. It is also possible to use Durarstrength D300 or D340 from Arkema, which have an acrylic core surrounded by a PMMA shell. Likewise, it is also possible to use the MBS developed by Rohm and Haas (Philadelphia, PA, USA), in particular Paraloid ^™ BTA 753.

These particles may be used alone or in admixture. Therefore, in a particular embodiment of the invention, a mixture of MBS (in particular, C303H or C301) particles and particles with a PMMA shell and an acrylonitrile core (in particular, D340 particles) is used.

Preferably, these particles are present in the composition in an amount of 2-20%, preferably 5-15% by weight of the composition.

Compositions according to the invention may also comprise acid monomers, such as acid monomers of the unsaturated carboxylic acid, maleic acid, crotonic acid, isophthalic acid and fumaric acid types known in the art, which can be polymerized by free radicals . It is also possible to add isobornyl acrylate (IBXA), 2-hydroxyethyl methacrylate (HEMA), 2-hydroxypropyl methacrylate (HPMA), 2-(perfluorooctyl)ethyl acrylate (POA ), tetrahydrofurfuryl acrylate (THFA) or isobutoxymethacrylamide (IBMA). Mixtures of these compounds may be added, especially HEMA/HPMA mixtures. Preference is given to methacrylic acid or acrylic acid. 2-10% of this compound is added, preferably 3-5%.

As seen above, compositions according to the invention may also comprise other elastomers, such as polychloroprene, such as Neoprene AD10 (ex Dupont, USA).

In a preferred embodiment thereof, the composition according to the invention may also comprise at least one further compound selected from the group consisting of curing accelerators, rheology modifiers or adhesion promoters.

Curing accelerators are used to accelerate the polymerization and curing of the adhesive when a catalyst is added. These are tertiary amines, preferably aromatic amines, such as dimethyl-p-toluidine and/or 2,2'-(p-tolylimino)diethanol.

Rheology modifiers serve to improve the good viscosity of the composition according to the invention, making it easy to apply to the surfaces to be bonded. Polyamides such as Disparlon 6200 or Disparlon 6500 (from Kusumoto Chemicals Ltd, Japan) can be used. Such rheology modifiers are generally used in amounts not exceeding 2% or 3% by weight of the composition.

In the context of the composition according to the invention, preferably, the phosphate-based adhesion promoter is methacrylated. In particular, phosphate ester adhesion promoters are used in which the ester is 2-hydroxyethyl phosphate methacrylate. In particular, it is available under the designation Genorad 40 (Rahn AG, Zurich, Switzerland). Such adhesion promoters are well known in the art and are particularly disclosed in US 4223115. Accordingly, the following substances are mentioned: 2-methacryloyloxyethyl phosphate, bis-(2-methacryloylethoxyphosphate), 2-acryloyloxyethyl phosphate, Di-(2-acryloylethoxyphosphate), methyl-(2-methacryloylethoxyphosphate), ethyl-(2-methacryloylethoxyphosphate), 2-methacrylic acid Mixtures of monophosphate and diphosphate esters of hydroxyethyl esters (particularly the one known under the name T-Mulz 1228 (Harcros Organics, Kansas City, US)) and similar compounds or derivatives.

Other components such as mineral fillers (TiO ₂ , CaCO ₃ , Al ₂ O ₃ , zinc phosphate), UV stabilizers (eg 2-hydroxyphenyl triazine, Tinuvin 400 from Ciba-Geigy), paraffins ( paraffin) and glass microspheres can also be added to the composition according to the invention. Free radical polymerization inhibitors such as BHT or benzoquinones such as naphthoquinone, hydroquinone or ethyl hydroquinone may also be added to increase the lifetime of the composition.

It is known that structural adhesives are formed from two components, the composition according to the invention and the catalyst for curing and setting the adhesive. The two components are kept in two different compartments and mixed together at the time of adhesive application. Such adhesives are also a subject of the present invention.

The catalyst is a free radical polymerization initiator, in particular, a peroxide based initiator, and is well known in the art. Benzoyl peroxide, tert-butyl peroxybenzoate or cumene hydroperoxide may be particularly selected. It is preferred when the catalyst comprises 5-40% by weight peroxide, in particular, about 20% by weight peroxide. In particular a paste comprising about 20% benzoyl peroxide is used.

The catalyst is used in a ratio of 1/1 to 1/30, preferably 1/5 to 1/30, even more preferably about 1/10 relative to the second component which is the composition according to the invention.

Thus, the present invention is based on the fact that elastomeric block copolymers (selected from block copolymers comprising styrene and isoprene, elastomeric block copolymers comprising styrene and butadiene or ethylene or combinations thereof mixture), a functionalized liquid elastomer (the elastomer is chosen in such a way that its Hildebrand solubility parameter is compatible with that of the elastomeric block copolymer) and butanediene-based The combined use of elastic polymeric particles of olefin and styrene makes it possible to obtain compositions for structural adhesives having an elongation at break equal to or greater than 80%, more preferably 100%, equal to or greater than Tensile shear strength of 10 MPa, 15 MPa or even 17 MPa (on aluminum) and high viscosity. This shear strength can be adjusted by the added amount of adhesion promoter or acid monomer as described above.

This result was completely unexpected, since the adhesive thus has properties which are far superior to those described in the prior art. Thus, patent US 6 433 091 suggests the use of core-shell polymers in structural adhesives and mentions MABS, MBS and ABS polymers. However, none of the compositions described in this patent contain all the components of the composition according to the invention.

Likewise, EP 1 256 615 does not mention the shear strength of the described adhesives, the only data being far inferior to the properties of the compositions according to the invention.

Furthermore, the adhesive also has excellent mechanical strength when used on composite materials. In fact, it is often found that the mechanical strength values observed on metals are not always replicated on composite materials.

Thus, the use of the composition according to the invention makes it possible to combine metals, plastics and composites to composites and thus enables particular application in the field of silo, boat or truck trailer construction. It can also be used in the field of automobile construction or in the field of railways.

Thus, the composition enables the adhesive bonding of one material to another, in particular metal, plastic, wood or composite material. Accordingly, the composition may be used in one or more of the following applications: metal/metal, metal/composite, metal/plastic, metal/wood, wood/plastic, wood/composite, wood/wood, plastic/composite, Plastic/plastic or composite/composite bonding.

The compositions according to the invention are therefore particularly beneficial when materials have to be bonded to composite materials.

The flexible methacrylate structural adhesives with high mechanical properties obtained with the composition according to the invention are resilient and resistant to shocks and vibrations. They make it possible to create adhesive joints between materials of the same or different chemical nature, such as concrete, wood, ceramics, glass, ferromagnets, aluminium, anodized aluminium, steel, galvanized Steel, stainless steel, painted metal, steel, copper, zinc, ABS, PVC, polyester, acrylic, polystyrene, gel-coat polyester or epoxy, composites, Glass-fiber reinforced composites, laminates, honeycomb structures and any painted or painted material.

They can also fill large gaps between substrates of different or variable thickness, roughness or planarity with better stress distribution. This property is increased due to the rheology of the compositions according to the invention.

The hardness of the composition according to the invention is measured by using a principle derived from the principle of slump cones (also called Abrams cones) with cones having a diameter of 4.5 cm. The Abrams cone method, used especially in the field of cement and mortar, makes it possible to measure the slump of a concrete cone under the influence of its own weight. The larger the slump, the more fluid the concrete is considered to be.

It has been observed that the slump of the formulations according to the invention is slight, ie they hold together under the influence of their own weight. Thus, it can be considered that the adhesives obtained from the compositions according to the invention behave like mortars due to their pasty consistency. Due to their pasty nature, these adhesives can be used as cement or mortar to fill gaps between two parts and allow bonding between two parts that are not in direct contact, while still maintaining the properties of thermoplastic adhesives, i.e. , especially the elasticity that mortar does not have.

It is thus possible to produce large-area assemblies with particularly large gaps, which join together without collapsing after assembly with relatively long setting times of a few minutes to more than one hour. In particular, this is highly advantageous in shipbuilding where deck-on-shell assemblies are prepared or fillet welds are used to join the partitions together.

The compositions according to the invention also have low shrinkage, especially after joining thermoplastics to polyester composites. Thus, the observed shrinkage of the compositions according to the invention is less than 2%, whereas prior art compositions generally have a shrinkage of 5-7%.

Thus, the consistency of the compositions according to the invention together with their low shrinkage makes them easy to use for obtaining particularly large adhesive joints.

Furthermore, the flexibility of the composition allows differential expansion forces between the substrates to be bonded over great lengths of several meters, while at the same time reducing or eliminating geometry (angles, roughness, flatness) defect.

Furthermore, the compositions according to the invention have a low exotherm during curing. This is also advantageous because excessive heat release, especially when bonding ABS thermoplastics (which can be used as reinforcements) to a polyester-based composite body, can stress the ABS and create bonding strains on the composite, It is visible after a paint cycle.

The application and activity sectors involved are:

Stiffeners, railings, frame structures, beams, stiffeners, plates, dividers, fasteners, supports, body components, stiffeners, inserts, cylindrical and conical components, hinges, frames, etc. combination; combination with laminations on partitions (lamination take-up on partitions), combination with fillers, requiring high mechanical strength; especially any combination of structural or mechanical components in the following areas: Shipbuilding, automobiles, railways (and infrastructure), aviation, aerospace, electronics, electromechanical and home appliances, military structures, indicating (and advertising) signals and panels, urban furniture, outdoor joinery (windows, glazed bays, window doors, entrance doors and garage doors), wind machines, containers, engineering structures and infrastructure (suspension bridges, offshore oil platforms and hangars, etc.), Construction and fasteners, curtain walls and solar panels.

The teaching provided by the present invention makes it possible for a person skilled in the art to vary the viscosity of the compositions according to the invention while maintaining mechanical properties such as elongation at break (greater than 80%) or shear strength.

For example, the following two types of compositions fall within the scope of the present invention, and the relative proportions of the various components can be adjusted by those skilled in the art.

Therefore, the following composition formulations can be used:

(a) Methacrylate monomer (MMA): equal to or greater than 40%;

(b) Elastomeric block copolymers (alone or in mixture): 15-21%;

(c) Elastomer (functionalized polybutadiene (VTB)): 8-10%; and

(d) Core-shell particles: 2-15%.

The following were also added: monomer (e) in an amount of 5-10%, Disparlon 0-3%, acid monomer 1-4% and Genorad 0-3%.

It is also possible to use the following composition preparations:

(a) Methacrylate monomer (MMA): equal to or greater than 40%;

(b) Elastomeric block copolymers (alone or in mixture): 2-15%;

(c) 8-10% functionalized polybutadiene (VTB), optionally mixed with 3-10% polychloroprene, or butadiene/acrylonitrile copolymer; and

(d) Core-shell particles: 10-25%.

The following may also be added: monomer (e) in an amount of 5-10%, Disparlon 0-3%, acid monomer 1-4% and Genorad 0-3%.

Example

The following examples illustrate the invention but do not limit the scope of the invention.

Example 1: Raw materials and methods used

The following components were used:

Methacrylate monomer (a): methyl methacrylate (MMA);

Acrylate monomer (e): lauryl methacrylate (LauMA) and/or 2-ethylhexyl acrylate (2EHA);

SIS copolymer (b): Kraton D1160 (Kraton Polymers);

SBS copolymer (b): Kraton D1102 (Kraton Polymers); or

SIBS copolymer (b): Kraton MD6455 (Kraton Polymers);

VTB 2000x168(Noveon，USA)(官能化聚丁二烯)；Functionalized liquid elastomer (c):

VTB 2000x168 (Noveon, USA) (functionalized polybutadiene);

Elastic polymeric particles (d): Clearstrength C301 (Arkema), Clearstrength C303H, Durarstrength D340 (Arkema), Paraloid BTA 753 (Rohm and Haas);

Acid monomer: methacrylic acid (MAA);

Adhesion Promoter: Genorad 40 Phosphate Methacrylate (Rahn AG);

Curing accelerators: dimethyl-p-toluidine (DMPT) and/or dihydroxyethyl-p-toluidine (DHEPT);

Rheology modifiers: Disparlon 6200, Disparlon 6500 (Kusumoto Chemicals);

Catalyst: 20% benzoyl peroxide ADERIS 1003 (Jacret, France);

as well as

Nitrile/butadiene elastomer: Chemigum P83 (Eliokem, France).

Experiments were carried out according to the following protocol:

- Tests for measuring tensile strength TS, elongation at break EB and modulus of elasticity or Young's modulus YM using the ISO 527 standard.

- observe the elongation using methods known to those skilled in the art, in particular described in the ISO 527 standard, with a pull rate of the adhesive constant 50 mm/min;

- Measure the tensile shear strength (SS) according to the ISO 4587 standard. Briefly, 2024T3 aluminum coupons measuring 100 x 25 x 1.6 mm (L x W x T) were used. The two test pieces were bonded to each other with an overlapping area of 25 x 12 mm (300 mm2) with an adhesive joint thickness of approximately 200-400 microns. The force required to break the adhesive bond is then measured by pulling the two test pieces; and

-Evaluate the tensile peel strength (PS) according to the ISO 14173 standard. Aluminum coupons measuring 100 x 25 x 1.5 mm or galvanized steel coupons measuring 100 x 25 x 0.8 mm were used, which were bonded with an overlap of 75 x 25 mm and an adhesive joint thickness of approximately 500 microns.

The viscosity of the adhesive was evaluated by the thickness of the adhesive that could be applied to a vertical surface without observing a downward slip.

Bonding to Composite Materials: Bonding tests were performed by bonding galvanized steel to polyester gel coat. Adhesion quality was evaluated according to the following convention:

++ = very good; + = moderate; - = weak

result

Samples comprising a mixture of the two elastomeric block copolymers (b) and the elastomer (c) were tested with and without particles (d).

sample 1 2 3 6 5 4 MMA 50.2 46.2 51 46 54 50 KratonD1160 16 16 16 15 16 16 KratonMD6455 5 5 5 5 5 5 VTB2000x168 10 10 10 10 10 10 C301 - 5 - 5 - 4 2EHA 8.8 8.8 8 9 5 5 MAA 5 4 4 4 4 4 Genorad 40 3 3 3 3 3 3 DMPT 1 1 1 1 1 1 Disparlon6500 1 1 2 2 2 2 total (weight) 100 100 100 100 100 100

The results obtained are as follows:

sample 1 2 3 6 5 4 SS (MPa) on aluminum 20.5 18.7 19.2 18.3 n.c.o. 20.5 PS (N/mm) on aluminum 17.3 15.4 14.3 13 n.c.o. 15.5 PS (N/mm) on galvanized steel 17.5 16.7 19.6 15 n.c.o. 15.3 TS (MPa) 9.6 10.1 9.8 9.6 11.1 10.5 EB(%) 251 189.8 156.3 202 84.6 151.1 YM (MPa) 95.7 118.5 150 104.6 201.8 164.4 Thickness (mm) 1-2 3-5 2-4 6-9 2-4 8-11 Gel coat bonding + ++ n.c.o. ++ ++ +

n.c.o.: Not performed.

These results demonstrate that the presence of elastic particles (d) makes it possible to increase the viscosity of the adhesive (measured by the thickness of the layer that can be applied without flow) without appreciable decrease in shear strength or elongation at break .

Similar results were observed when mixing other block copolymers (SIS+SBS).

Compounds comprising a (a single) block copolymer (b) were also tested:

sample 8 9 10 11 12 13 14 MMA 54 50 50 54 50 54 50 KratonD1102 - - - twenty one twenty one - - KratonD1160 - - - - - twenty one twenty one KratonMD6455 twenty one twenty one twenty one - - - - VTB2000x168 10 10 10 10 10 10 10 C301 - 5 4 - 4 - 4 2EHA 5 5 5 5 5 5 5 MAA 4 4 4 5 4 5 4 Genorad 40 3 3 3 3 3 3 3 DMPT 1 1 1 1 1 1 1 Disparlon6500 2 1 2 1 2 1 2 total (weight) 100 100 100 100 100 100 100

The results obtained are as follows:

sample 8 9 10 11 12 13 14 SS (MPa) on aluminum twenty two 20 22.2 twenty two 21.4 21.1 n.c.o. PS (N/mm) on aluminum 16.7 13 16.6 12.4 14.9 20.5 n.c.o. PS (N/mm) on galvanized steel 13.1 13.5 16.8 8.9 18.7 17.2 n.c.o. TS (MPa) 10.5 10.9 11 12.4 12.4 9.4 11.5 EB(%) 86.5 128.8 140.4 43.2 146.3 50.2 87.3 YM (MPa) 178.6 175.6 177.8 268 228.3 173.8 210.2 Thickness (mm) 2-4 3-5 6-9 1-2 6-9 1-2 6-9 Gel coat bonding ++ ++ ++ + ++ + n.c.o.

Apparently, the combined presence of components (b), (c) and (d) makes it possible to maintain excellent tensile shear strength to improve elongation at break (elasticity) and to increase viscosity. It should also be noted that the observed peel and tensile strength results were maintained.

Different elastic core-shell particles were also tested:

sample 15 16 17 MMA 46 46 45.1 Kraton MD6455 twenty one twenty one 18.9 Kraton D1160 - - - VTB 2000x168 10 10 9 Neoprene AD10 - - - C303H - 10 - D340 10 - 14 BTA753 - - - 2EHA 5 5 5 Lauryl MA - - - MAA 4 4 4 Genorad 40 3 3 3 DMPT 1 1 1 Disparlon 6500 0 0 0 total (weight) 100 100 100

The following results were obtained:

sample 15 16 17 SS (MPa) on aluminum 22.1 23.5 20.0 TS (MPa) 9.7 10 9.9 EB(%) 127.9 97.0 97.2 YM (MPa) 200.1 165.6 170.2 Thickness (mm) 8-11 14-18 18-20 Gel coat bonding ++ ++ ++

Other formulations including mixtures of block copolymers (b) were also tested.

sample 19 20 twenty one twenty two twenty three twenty four 25 MMA 53.72 55 43.3 40.3 40.3 44.3 44.3 KratonD1160 - 5 15 15 15 16 16 KratonMD6455 7.14 15 5 5 5 5 5 VTB2000x168 8.2 10 10 10 10 10 10 2EHA 4.1 - 5 5 5 5 5 Lauryl MA 5.1 1 5 5 5 5 5 C303H 15.3 10 - 15 - - - D340 - - 15 - - 10 - BTA753 - - - - 15 - - MAA 2 1 1 1 1 1 1 DHEPT - - 0.5 0.5 0.5 0.5 0.5 DMPT 0.3 1 0.2 0.2 0.2 0.2 0.2 Neoprene AD10 4.14 - - - - - - Chemigum P83 - - - - - - 10 Disparlon6500 - 2 - 3 3 3 3 total (weight) 100 100 100 100 100 100 100

The following results were obtained:

sample 19 20 twenty one twenty two twenty three twenty four 25 TS (MPa) 7.2 5.5 6.4 7 6.1 6.2 3.2 EB(%) 132.8 103.5 180.2 291 210.3 199.8 130.3 YM (MPa) 108.1 54.3 111.6 102.3 78.9 116.9 35.5 Thickness (mm) 15-20 12-16 20-25 20-25 20-25 20-25 10-15

These results show that the use of NBR is not as effective as particle (d) used in the context of the present invention.

All these results demonstrate that by mixing components (a), (b), (c) and (d), it is possible to obtain adhesives with high viscosity while maintaining good elongation at break.

Claims (16)

1. A composition for use in structural adhesives, comprising: (a) at least one methacrylate monomer; (b) at least one elastomeric block copolymer comprising styrene and at least one second monomer; (c) at least one elastomer selected in such a way that its Hildebrand solubility parameter is compatible with that of the block copolymer used; and (d) Particles formed from a thermoplastic shell and an elastic core. 2. Composition according to claim 1, characterized in that the second monomer of the elastomeric block copolymer (b) is selected from isoprene, butadiene or ethylene. 3. Composition according to claim 2, characterized in that the elastomeric block copolymer is selected from the group consisting of styrene-isoprene-styrene (SIS), styrene-butadiene-styrene (SBS) Or styrene-isoprene-butadiene-styrene (SIBS) copolymer or mixtures thereof. 4. Composition according to any one of claims 1 to 3, characterized in that it comprises 5-30% by weight of said elastomeric block copolymer (b) or a mixture of elastomeric block copolymers (b). 5. Composition according to any one of claims 1 to 4, characterized in that the elastomer (c) is selected from functionalized or unfunctionalized polybutadiene, polyisoprene or these components mixture. 6. Composition according to any one of claims 1 to 5, characterized in that it comprises 4-20% by weight of said elastomer (c). 7. Composition according to any one of claims 1 to 6, characterized in that the particles (d) are selected from the group consisting of acrylonitrile-butadiene-styrene, methacrylate-butadiene-styrene, Methacrylate-acrylonitrile-butadiene-styrene or methacrylate-acrylonitrile particles or mixtures thereof. 8. Composition according to any one of claims 1 to 7, characterized in that it comprises 2-20% by weight of said particles (d). 9. Composition according to any one of claims 1 to 8, characterized in that it also comprises at least one acrylate monomer (e) in which the alcohol moiety has at least one linear chain containing at least 6 carbon atoms. 10. The composition according to claim 9, characterized in that said one acrylate monomer (e) is a methacrylate or acrylate monomer. 11. Composition according to any one of claims 9 and 10, characterized in that it comprises a mixture of two acrylate monomers (e). 12. Composition according to any one of claims 9 to 11, characterized in that it comprises less than 10% by weight of acrylate monomers (e). 13. Composition according to any one of claims 1 to 12, characterized in that it also comprises polychloroprene. 14. Composition according to any one of claims 1 to 13, characterized in that it also comprises at least one additional compound selected from the group consisting of curing accelerators, rheology modifiers, adhesion promoters or acid monomers. 15. Use of a combination of an elastomeric block copolymer, a functionalized liquid elastomer, and elastomeric polymeric particles in the preparation of a composition for use as a structural adhesive, said elastomeric block copolymer being selected from the group consisting of styrene and isoprene A block copolymer comprising an elastomeric block copolymer of styrene and a second monomer, the functionalized liquid elastomer having a Hilderbrand solubility parameter that is comparable to that of the elastomeric block copolymer Brand solubility parameters are selected in such a way that the structural adhesive has an elongation at break equal to or greater than 80% and such that a thickness of at least 3 to 5 mm of the composition is applied to a vertical surface without the force of gravity The rheology of the flow under influence. 16. Use of a composition according to any one of claims 1 to 14 for adhering one material to another.