WO2021189402A1

WO2021189402A1 - E-coatable compositions and use thereof in welding sealer applications

Info

Publication number: WO2021189402A1
Application number: PCT/CN2020/081597
Authority: WO
Inventors: Fangyuan LIU; Elyes Jendoubi; Weiming Zhang
Original assignee: Sika Technology Ag
Priority date: 2020-03-27
Filing date: 2020-03-27
Publication date: 2021-09-30

Abstract

Disclosed is a composition comprising an acrylate polymer AP, epoxy resin A, a latent hardener for epoxy resins, a plasticizer PL and a electrically conductive carbon allotrope KA selected from the list consisting of carbon blacks (KA-1) and graphenes (KA-2). A method for providing sealing to a structure of a manufactured article, preferably an automotive vehicle, is also disclosed. The composition can be used as welding sealer compositions, which, in the uncured state, are sufficiently coated with CED coating after the CEDC bath.

Description

E-coatable compositions and use thereof in welding sealer applications

Technical field

The invention relates to plastisol compositions, which are used for sealing of metal surfaces separated by a gap from each other. In particular, the invention relates to plastisol compositions, which can be applied to a structure of a mode of transport, such an automotive vehicle, which assist in or at least do not interfere with manufacturing steps of the mode of transport.

Background of the invention

Various existing plastisol are used for a variety of applications including surface coating for waterproofing and sealing applications. Typically, plastisol consists of PVC or PVC-alternative particles suspended in a liquid plasticizer with additional other agents to achieve desired properties. Compositions containing acrylate polymers and plasticizers are commonly used to for the sealing of structural components of manufactured articles, in particular structural components of transportation vehicles and white goods.

It is generally desired that the application of these compositions either assists in or at least do not interfere with the processing, formation, or assembly of the manufactured article. For example, it is critical that the compositions, when positioned in a weld location, does not inhibit welding of the components. Furthermore, the compositions materials should provide good bonding with metal surfaces, in particular to oiled metal surfaces.

Such compositions are also used in applications, where portions of structures of manufactured articles, such as automotive vehicles, are bonded to each other by spot welding. In some applications, the structures are bonded to each by welds, which extend through the applied composition. The compositions used in these applications are also known as “welding sealer compositions” or “weld-through compositions” . In a typical welding application, the composition is applied to a portion of a structure, which is subsequently welded to form a bond with a portion of another structure. The welding of the structures can be conducted using, for example, electric resistance welding. In this case a first electrode is contacted with an outer surface of a first substrate and a second electrode is contacted with an outer surface of a second substrate to be welded with the first substrate. The composition is positioned between the first and second substrates such that at least part of it is located between the electrodes. The electrodes are then moved towards each other resulting in displacement of part of the composition. Simultaneously or after moving of the electrodes, an electrical current is induced to flow between the electrodes thereby forming a weld between a portion of the first and second substrate and through the composition. After the welding, the composition can further be activated to expand or to cure or both.

When the structures are part of an automotive vehicle, these structures pass through a CEDC (cathodic electrodeposition dip coating, in this document also called “e-coating” ) bath at the end of the body shop, in which it is coated with a CEDC solution, which is then baked in a CEDC oven. Sufficient surface coating, especially at the edges where the sealing compositions are in contact with the substrate, is the basis for long-term use of the vehicle, as it makes a significant contribution to corrosion resistance.

However, it has been shown that the applied and not yet cured sealing compositions, like the before mentioned “welding sealer compositions” or “weld-through compositions” , in the CEDC bath are not or only sparsely covered with the CED coating. This not only results in reduced corrosion resistance but also in aesthetically inferior surfaces.

Summary of the invention

The object of the present invention is to provide a composition, which can be used for providing welding sealer compositions, which, in the uncured state, are sufficiently coated with CED coating after the CEDC bath. Especially in the uncured state, a sufficient coating of the applied composition with CDC coating is particularly demanding. Surprisingly, it was found that a composition according to claim 1 can achieve this object.

Other subjects of the present invention are presented in other independent claims. Preferred aspects of the invention are presented in the dependent claims.

Detailed description of the invention

The subject of the present invention is composition comprising:

a) at least one acrylate polymer AP;

b) at least one epoxy resin A having on average more than one epoxide group per molecule;

c) at least one latent hardener for epoxy resins;

d) at least one plasticizer PL; and

e) at least one electrically conductive carbon allotrope (KA) selected from the list consisting of carbon blacks (KA-1) and graphenes (KA-2) .

The amount of carbon blacks (KA-1) is 2 -9 wt. -%, and/or the amount of graphenes (KA-2) is 4 –9 wt. -%, based on the total weight of the composition. The total amount of electrically conductive carbon allotrope KA is from 2 -9 wt. -%, based on the total weight of the composition.

Substance names beginning with "poly" designate substances which formally contain, per molecule, two or more of the functional groups occurring in their names. For instance, a polyol refers to a compound having at least two hydroxyl groups. A polyether refers to a compound having at least two ether groups.

The term “plastisol” preferably refers to dispersions of plastics, in particular polymers produced by emulsion polymerization or microemulsion polymerization, in high-boiling organic compounds, which act as plasticizers for the polymer at higher temperatures. When the plastisols are heated, the plasticizers diffuse into the dispersed plastic particles, where they are stored between the macromolecules, thereby causing the plastics to plasticize. When cooling, the plastisols gel into flexible, dimensionally stable system. More preferably, the term refers to the definition described in the

Chemie Lexikon, online version, Georg Thieme Verlag, retrieved on March 19, 2020.

The term “polymer” refers to a collective of chemically uniform macromolecules produced by a polyreaction (polymerization, polyaddition, polycondensation) where the macromolecules differ with respect to their degree of polymerization, molecular weight and chain length. The term also comprises derivatives of said collective of macromolecules resulting from polyreactions, that is, compounds which are obtained by reactions such as, for example, additions or substitutions, of functional groups in predetermined macromolecules and which may be chemically uniform or chemically non-uniform.

The term “molecular weight” refers to the molar mass (g/mol) of a molecule or a part of a molecule, also referred to as “moiety” . The term “average molecular weight” refers to number average molecular weight (M _n) of an oligomeric or polymeric mixture of molecules or moieties. The molecular weight may be determined by gel permeation chromatography.

The term “glass transition temperature” (T _g) refers to the temperature above which temperature a polymer component becomes soft and pliable, and below which it becomes hard and glassy. The glass transition temperature (T _g) is preferably determined by dynamical mechanical analysis (DMA) as the peak of the measured loss modulus (G”) curve using an applied frequency of 1 Hz and a strain level of 0.1 %.

The term “room temperature” designates a temperature of 23℃.

The composition contains preferably 5 –40 wt. -%, 10 –40 wt. -%, 12.5 –40 wt. -%, more preferably 15 –35 wt. -%, even more preferably 17.5 –32.5 wt. -%, most preferably 20 –30 wt. -%, based on the total weight of the composition, of at least one acrylate polymer AP.

Preferably, the acrylate polymer AP is selected from the list consisting of polymers of methyl acrylate, ethyl acrylate methyl methacrylate, propyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and any copolymers thereof.

The acrylate polymers AP can be available from commercial sources such as Degalan BM 310 (homopolymer from Evonik) , Degalan 4944F (homopolymer from Evonik) , Kane Ace UC521 (manufactured by Kaneka) , Kane Ace UC506 and Kane Ace UC508.

Preferably, more than 40%, more than 50%, more than 60%, more than 70%, more than 80%, or more than 90%of the acrylate polymer AP is methacrylate polymer or a copolymer containing methacrylate.

Preferably, the glass transition temperature (Tg) of the acrylate polymer AP is from 60 ℃ to 120 ℃, from 70 ℃ to 100 ℃, more preferably from 75 ℃ to 80 ℃.

The acrylate polymer AP can take a variety of forms as delivered from the manufacturer: bead polymers, pellets, granules, powders, spray dried emulsion polymers, etc. Before use, the median particle size d ₅₀ of the acrylate polymer AP can range from 1 to 100 μm, preferably from 10 to 80 μm, from 20 to 60 μm, most preferably from 40 to 60 μm.

Preferably, the acrylate polymer AP has the following attributes: (i) bulk density of about 350 to about 450 grams per liter; (ii) glass transition temperature from 70 ℃. to 80 ℃.; and (iii) median particle size d ₅₀ of 40 to 60 microns.

The composition comprises at least one epoxy resin A having on average more than one epoxide group per molecule. The epoxide group is preferably in the form of a glycidyl ether group.

The fraction of the epoxy resin A having on average more than one epoxide group per molecule is preferably from 0.5 -15 wt. -%, 1 -10 wt. -%, 1.5 -7.5 wt. -%, 1.5 -5 wt. -%, more preferably 2 -4 wt. -%, based on the total weight of the composition.

The epoxy resin A having on average more than one epoxide group per molecule is preferably a liquid epoxy resin or a solid epoxy resin, more preferably a liquid epoxy resin. The term “solid epoxy resin” is very familiar to the person skilled in the epoxide art and is used in contrast to “liquid epoxy resins” . The glass transition temperature of solid resins is above room temperature, meaning that at room temperature they can be comminuted into pourable powders. It is preferred if more than 70 wt. -%, more preferred more than 80 wt. -%, more than 90 wt. -%, more than 95 wt. -%, more than 98 wt. -%, of the epoxy resin A is a liquid epoxy resin.

Preferred epoxy resins have the formula (II)

In this formula, the substituents R’ and R” independently of one another are either H or CH ₃.

In solid epoxy resins, the index s has a value of > 1.5, more particularly from 2 to 12.

Solid epoxy resins of this kind are available commercially, for example, from Dow or Huntsman or Hexion.

Compounds of the formula (II) having an index s of 1 to 1.5 are referred to by the person skilled in the art as semi-solid epoxy resins. For the purposes of the present invention, they are considered likewise to be solid resins. Preferred solid epoxy resins, however, are epoxy resins in the narrower sense, in other words where the index s has a value of > 1.5.

In the case of liquid epoxy resins, the index s has a value of less than 1.

Preferably s has a value of less than 0.2.

The resins in question are therefore preferably diglycidyl ethers of bisphenol A (DGEBA) , of bisphenol F and also of bisphenol A/F. Liquid resins of these kinds are available for example as

GY 250,

PY 304,

GY 282 (Huntsman) or D.E.R. ^TM 331 or D.E.R. ^TM 330 (Dow) or Epikote 828 (Hexion) .

Of further suitability as epoxy resin A are what are called epoxy novolacs.

These compounds have, in particular, the following formula:

where R2 =

or CH ₂, R1 = H or methyl and z = 0 to 7.

More particularly these are phenol-epoxy or cresol-epoxy novolacs (R2 = CH ₂) . Epoxy resins of these kinds are available commercially under the tradename EPN or ECN and also

from Huntsman, or within the product series D.E.N. ^TM from Dow Chemical.

The epoxy resin A is preferably a liquid epoxy resin of the formula (II) .

The composition further comprises at least one latent hardener for epoxy resins. Latent hardeners are substantially inert at room temperature and are activated by elevated temperature, typically at temperatures of 70 ℃ or more, thereby initiating the curing reaction of the epoxy resin. The customary latent hardeners for epoxy resins can be used. Preference is given to a latent epoxy resin hardener containing nitrogen.

The latent hardener is preferably selected from the group consisting of dicyandiamide, guanamines, guanidines, aminoguanidines and derivatives thereof, substituted ureas, imidazoles and amine complexes, preferably dicyandiamide.

The amount of the latent hardener is preferably 0.1 to 10 wt%, more preferably 0.2 to 5 wt%, 0.5 -3 wt%, 0.5 -2 wt%, more particularly 0.75 –1.5 wt%, based on the total weight of the composition.

The weight ratio of the total amount of the at least one epoxy resin A having on average more than one epoxide group per molecule to the total amount of the latent hardener is preferably 6: 1 to 1: 1, 5: 1 to 2: 1, more preferably 4: 1 to 2: 1.

Further, the composition further comprises at least one plasticizer PL.

The at least one plasticizer PL is preferably selected from the list consisting of:

- dibasic acid esters, preferably dioctyl adipate (DOA) , a dioctyl azelate (DOZ) , and a dioctyl sebacate (DOS) ;

- phosphoric acid ester series, preferably tricresyl phosphate (TCP) , a trioctyl phosphate (TOF) , a trixylenyl phosphate (TXP) , a monooctyl diphenyl phosphate, and a monobutyl-dixylenyl phosphate (B-Z-X) ;

- benzoic acid ester;

- esters, preferably tributyl citrate ester, a trioctyl-acetyl citric acid ester, a trimellitic acid ester, a citric acid ester, a sebacic acid ester, an azelaic acid ester, a tri-or tetraethylene glycol ester of maleate C6-C10 fatty acid, an alkyl sulfonic acid ester, and a methyl acetyl ricinoleate;

- saturated fatty acid glyceride;

- epoxidized vegetable oil;

- phthalate, preferably diisononyl phthalate (DINP) or dioctyl phthalate (DOP) .

Most preferably, the at least one plasticizer PL is a phthalate, more preferably diisononyl phthalate (DINP) or dioctyl phthalate (DOP) , most preferred DINP.

The composition preferably comprises 5 –50 wt. -%, 10 –40 wt. -%, 12.5 –40 wt. -%, more preferably 15 –35 wt. -%, even more preferably 17.5 –32.5 wt. -%, most preferably 20 –30 wt. -%, based on the total weight of the composition, of the at least one plasticizer PL.

The weight ratio between the total weight of the at least one plasticizers PL and the total weight of the at least one acrylate polymer AP preferably ranges from 1: 10 to 20: 10. More preferred ranges of the weight ratio include from 2: 10 to 15: 10, from 2: 10 to 15: 10, from 5: 10 to 15: 10; from 5: 10 to 10: 10, from 6: 10 to 10: 10, and from 8: 10 to 10: 10.

The composition contains at least one electrically conductive carbon allotrope KA selected from the list consisting of carbon blacks (KA-1) and graphenes (KA-2) , the amount of carbon blacks (KA-1) being 2 -9 wt. -%, and/or the amount of graphenes (KA-2) 4 –9 wt. -%, based on the total weight of the composition. The total amount of electrically conductive carbon allotrope KA is from 2 -9 wt. -%, based on the total weight of the composition.

The amount of carbon blacks (KA-1) is preferably from 2 -8 wt. -%, 2.5 –7.5 wt. -%, 3 -7 wt. -%, 3.5 -6 wt. -%, preferably 3.5 –5.5 wt. -%, more preferably 3.5 –5 wt. -%, most preferably 3.5 –4.5 wt. -%.

The amount of graphenes (KA-2) is preferably from 4.5 -8 wt. -%, 4.5 –7.5 wt. -%, preferably 5 –7.5 wt. -%, more preferably 5 -7 wt. -%, most preferably 5 –6.

Furthermore, the above-mentioned quantity ranges ensure an adequate coating with after the CED coating in the uncured state. In particular, these compositions achieve a value of at least 6 after the CED coating has been carried out in the example part, which corresponds to a partially overcoated bead that are completely coated at the edges, as shown in Tables 3-4. In addition, the above-mentioned quantity ranges ensure at the same time a preferable viscosity at 25 ℃.

In a preferred embodiment of the invention, carbon blacks (KA-1) are more than 60 wt. -%, more than 70 wt. -%, more than 80 wt. -%, more than 90 wt. -%, more than 95 wt. -%, more than 98 wt. -%, preferably 100 wt. -%, of the total weight of the electrically conductive carbon allotrope KA.

In another preferred embodiment of the invention, graphenes (KA-2) are more than 60 wt. -%, more than 70 wt. -%, more than 80 wt. -%, more than 90 wt. -%, more than 95 wt. -%, more than 98 wt. -%, preferably 100 wt. -%, of the total weight of the electrically conductive carbon allotrope KA.

Electrically conductive carbon allotropes KA, which are particle and /or particle-shaped, are preferred. It is particularly preferred to use conductive carbon allotropes (KA) , the individual particles or particles having a shape selected from the list consisting of granular, spherical, elongated, plate-shaped, scaly, cylindrical, conical and frustoconical. Structures of this type can be introduced or incorporated particularly well into the coating composition according to the invention while ensuring high electrical conductivity.

It is preferably an electrically conductive carbon allotrope KA with an average particle size D ₅₀ in the range from 0.05 nm to 1,000 μm, in particular 0.1 nm to 800 μm, preferably 1 nm to 600 μm, preferably 10 nm to 500 μm.

The electrically conductive carbon allotropes KA used according to the invention can optionally be functionalized. Such functionalization are generally known to the person skilled in the art.

The electrically conductive carbon allotrope KA can be conductive carbon blacks (KA-1) . Conductive carbon blacks (KA-1) are advantageous whose primary particles have an average particle size, in particular an average particle size D ₅₀, in the range from 1 nm to 1,000 nm, in particular 5 nm to 500 nm, 5 nm to 100 nm, preferably 10 nm to 50 nm. The size can be determined in particular on the basis of an electron microscopic measurement.

Also advantageous are electrically conductive carbon blacks (KA-1) , which have a specific surface area (BET surface area, in particular measured according to N ₂SA) in the range from 10 m ² /g to 2,000 m ² /g, in particular 100 m ²/g to 1,800 m ²/g, preferably 500 m ² /g to 1,700 m ²/g, preferably 1000 m ² /g to 1,600 m ²/g.

The electrically conductive carbon allotrope KA can be graphenes (KA-2) , in particular modified graphenes. It can also be a single-layer or multi-layer graphene. They are preferably graphenes with a thickness of 1-50 nm, 2-20 nm, in particular 3-10 nm.

It is also advantageous if the composition contains less than 5%by weight, less than 2%by weight, less than 1%by weight, less than 0.5%by weight, in particular less than 0.1%by weight. %, most preferably less than 0.01%by weight, of conductive polymers, based on the total weight of the composition.

As far as the conductive polymers, which can also be referred to synonymously as electrically self-conducting polymers, these generally represent plastics with electrical conductivity. In particular, they are conductive polymers selected from the group consisting of polyacetylenes, polyanilines, polyparaphenylenes, polystyrenes, Polythiophenes, polyethylene dioxythiophenes (PEDOT) , polyethylene dioxythiophenes: polystyrene sulfonates (PEDOT: PSS) and polyphenylene vinylenes, in particular polyacetylenes, polyanilines, polyparaphenylenes, polystyrenes and polythiophenes.

It is also advantageous if the composition contains less than less than 5%by weight, less than 2%by weight, less than 1%by weight, less than 0.5%by weight, in particular less than 0.1%by weight. %, most preferably less than 0.01%by weight, additives selected from the list consisting of carbon fibers, graphite, silicon carbide, metal oxides, metals, in particular iron and zinc, ammonium salts, fillers containing heavy metals or metals, in particular fillers based on titanium dioxide containing antimony and tin or mica, ionic liquids and ionic and non-ionic surfactants, based on the total weight of the one-part thermosetting epoxy resin composition.

It is also advantageous if the composition contains less than less than 10%by weight, less than less than 5%by weight, less than 2%by weight, less than 1%by weight, less than 0.5%by weight, in particular less than 0.1%by weight. %, most preferably less than 0.01%by weight, of PVC. This is advantageous because the high temperatures required to cure the composition cause the PVC to release toxic hydrogen chloride gas which posed an occupational hazard to those working with the composition.

Preferably, the composition further comprises at least one process oil.

Preferably, the at least one process oil, if used, is present in the composition in an amount of 1 –10 wt. -%, more preferably 2 –8 wt. -%, even more preferably 3 –6 wt. -%, based on the total weight of the composition.

Suitable process oils include mineral oils and synthetic oils. The term “mineral oil” refers in the present disclosure hydrocarbon liquids of lubricating viscosity (i.e., a kinematic viscosity at 100 ℃ of 1 cSt or more) derived from petroleum crude oil and subjected to one or more refining and/or hydroprocessing steps, such as fractionation, hydrocracking, dewaxing, isomerization, and hydrofinishing, to purify and chemically modify the components to achieve a final set of properties. In particular, the term “mineral” refers in the present disclosure to refined mineral oils, which can be also characterized as Group I-III base oils according the classification of the American Petroleum Institute (API) .

Preferred mineral oils to be used as the at least one process oil include paraffinic, naphthenic, and aromatic mineral oils. Particularly suitable mineral oils include paraffinic and naphtenic oils, preferably containing relatively low amounts of aromatic moieties, such as not more than 25 wt. -%, preferably not more than 15 wt. -%, based on the total weight of the mineral oil.

According to a preferred embodiment, the composition further comprises at least one particulate filler F, preferably selected from the group consisting of ground or precipitated calcium carbonate, lime, calcium-magnesium carbonate, talcum, gypsum, barite, pyrogenic or precipitated silica, silicates, mica, wollastonite, kaolin, feldspar, chlorite, bentonite, montmorillonite, dolomite, quartz, cristobalite, calcium oxide, aluminum hydroxide, magnesium oxide, hollow ceramic spheres, hollow glass spheres, hollow organic spheres, glass spheres, kaolin and functionalized alumoxanes. Preferred solid particulate fillers include both organically coated and also uncoated commercially available forms of the fillers included in the above presented list.

The at least one solid particulate filler F is preferably in the form of finely divided particles. The term “finely divided particles” refers to particles, whose median particle size d ₅₀ does not exceed 500 μm, in particular, 250 μm. The term “median particle size d ₅₀ “refers in the present document to a particle size below which 50%of all particles by volume are smaller than the d ₅₀ value. The particle size distribution can be determined by sieve analysis according to the method as described in ASTM C136/C136M -14 standard ( “Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates) .

According to one or more embodiments, the at least one particulate filler F comprises at least one filler selected from the list consisting of ground or precipitated calcium carbonate, calcium oxide, lime, calcium-magnesium carbonate, talcum, gypsum, graphite, barite, silica, silicates, mica, wollastonite, kaolin, and mixtures thereof, more preferably selected from the list consisting of ground or precipitated calcium carbonate, calcium oxide, silica, kaolin, and mixtures thereof.

According to one or more embodiments, the at least one particulate filler F comprises 10 –50 wt. -%, preferably 15 –45 wt. -%, more preferably 20 –40 wt. -%, even more preferably 25 –35 wt. -%of the total weight of the composition.

The composition can further comprise at least one blowing agent BA.

A suitable blowing agent may be a chemical or physical blowing agent.

Chemical blowing agents are organic or inorganic compounds that decompose under influence of, for example temperature or humidity, while at least one of the formed decomposition products is a gas. Physical blowing agents include, but are not limited to, compounds that become gaseous at a certain temperature. Preferably, the at least one blowing agent BA is a chemical blowing agent.

Suitable chemical blowing agents include, but are not limited to, azo compounds, hydrazides, nitroso compounds, carbamates, carbazides, bicarbonates, polycarboxylic acids, and salts of polycarboxylic acids.

According to one or more embodiments, the at least one blowing agent BA is selected from the group consisting of azodicarbonamide, azoisobutytronitrile, azocyclohexyl nitrile, dinitrosopentamethylene tetramine, azodiamino benzene, benzene-1, 3-sulfonyl hydrazide, calcium azide, 4, 4′-diphenyldisulphonyl azide, p-toluenesulphonyl hydrazide, p-toluenesulphonyl semicarbazide, 4, 4’-oxybis (benzenesulphonylhydrazide) , trihydrazino triazine, and N, N’-dimethyl-N, N’-dinitrosoterephthalamide, and combinations thereof and the like.

Also suitable as chemical blowing agents are dual chemical systems, such as acid/base systems that generate gases upon reaction, for example a combination of sodium hydrogen carbonate and citric acid. According to one or more embodiments, the at least one blowing agent BA comprises a mixture of bicarbonate and polycarboxylic acids and/or salts thereof, preferably a mixture of sodium bicarbonate and citric acid and/or citrate.

Suitable physical blowing agents further include expandable microspheres, consisting of a thermoplastic shell filled with thermally expandable fluids or gases. Suitable expandable microspheres are commercially available, for example, under the trademark of

microspheres (from AkzoNobel) .

According to one or more embodiments, the at least one blowing agent BA comprises or consists of at least one blowing agent selected from the group consisting of azodicarbonamide, expandable microspheres, and 4, 4′-oxybis (benzenesulphonylhydrazide) .

According to one or more embodiments, the at least one blowing agent BA comprises or consists of azodicarbonamide.

According to one or more embodiments, the at least one blowing agent BA comprises 0.1 –5 wt. -%, preferably 0.25 –3.5 wt. -%, more preferably 0.5 –3 wt. -%, even more preferably 1 –3 wt. -%of the total weight of the composition. Such an amount, especially if the blowing agent is azodicarbonamide, provides the advantage of uniform/even expansion behaviour.

In case the composition contains at least one blowing agent BA, the composition after curing preferably has a volume increase compared to the uncured composition of not more than 500 %, preferably not more than 400 %, more preferably not more than 350 %, whereby the volume increase is determined using the DIN EN ISO 1183 method of density measurement (Archimedes principle) in deionised water in combination with sample mass determined by a precision balance. It is further preferred that the composition after curing has a volume increase compared to the uncured composition in the range of 25 –500 %, preferably 50 –400 %, more preferably 75 –350 %, even more preferably 100 –350 %.

Preferably, the composition has a viscosity at 25 ℃ of 300-5000 Pa*s, 500-4000 Pa*s, 750-3500 Pa*s preferably 1000-3000 Pa*s, in particular 1500-2500 Pa*s.

Preferably, the composition has a viscosity at 50 ℃. of 500-4000 Pa*s, 500-3000 Pa*s preferably 1000-2500 Pa *s, in particular 1300-2000 Pa*s.

Viscosities with higher ranges are less preferred since they are less suitable for industrial adhesive application processes.

The viscosity is preferably determined oscillographically by a rheometer with a heated plate (MCR 201, AntonPaar) (gap 1000 μm, measuring plate diameter: 25 mm (plate /plate) , deformation 0.01 at 5 Hz, heating rate 10 ℃/min) .

In a preferred embodiment, the composition comprises:

- at least one acrylate polymer AP in an amount of 5 –40 wt. -%, 10 –40 wt. -%, 12.5 –40 wt. -%, more preferably 15 –35 wt. -%, even more preferably 17.5 –32.5 wt. -%, most preferably 20 –30 wt. -%, based on the total weight of the composition;

- at least one epoxy resin A having on average more than one epoxide group per molecule in an amount of 0.5 -15 wt. -%, 1 -10 wt. -%, 1.5 -7.5 wt. -%, 1.5 -5 wt. -%, more preferably 2 -4 wt. -%, based on the total weight of the composition;

- at least one latent hardener for epoxy resins, selected from the group consisting of dicyandiamide, guanamines, guanidines, aminoguanidines and derivatives thereof, substituted ureas, imidazoles and amine complexes, preferably dicyandiamide;

- at least one plasticizer PL, whereby wherein the at least one plasticizer PL is preferably a phthalate, more preferably diisononyl phthalate (DINP) or dioctyl phthalate (DOP) , most preferred DINP, in an amount of 5 –50 wt. -%, 10 –40 wt.-%, preferably 12.5 –40 wt. -%, more preferably 15 –35 wt. -%, even more preferably 17.5 –32.5 wt. -%, most preferably 20 –30 wt. -%, based on the total weight of the composition:

- preferably at least one particulate filler F, preferably selected from the list consisting of ground or precipitated calcium carbonate, calcium oxide, silica, kaolin, and mixtures thereof, in an amount of 10 –50 wt. -%, preferably 15 –45 wt. -%, more preferably 20 –40 wt. -%, even more preferably 25 –35 wt. -%of the total weight of the composition;

- preferably at least one process oil, in an amount of 1 –10 wt. -%, more preferably 2 –8 wt. -%, even more preferably 3 –6 wt. -%, based on the total weight of the composition; and

- at least one electrically conductive carbon allotrope KA selected from the list consisting of carbon blacks (KA-1) and graphenes (KA-2) ,

the amount of carbon blacks (KA-1) being 2 -9 wt. -%, 2.5 –7.5 wt. -%, 3 -7 wt. -%, 3.5 -6 wt. -%, preferably 3.5 –5.5 wt. -%, more preferably 3.5 –5 wt. -%, most preferably 3.5 –4.5 wt. -%, based on the total weight of the composition

and/or

the amount of graphenes (KA-2) being 4 –9 wt. -%, 4.5 -8 wt. -%, 4.5 –7.5 wt. -%, preferably 5 –7.5 wt. -%, more preferably 5 -7 wt. -%, most preferably 5 –6, based on the total weight of the composition,

wherein the total amount of electrically conductive carbon allotrope KA is from 2 -9 wt. -%, based on the total weight of the composition.

In said composition it is preferred if the weight ratio of the total amount of the at least one epoxy resin A having on average more than one epoxide group per molecule to the total amount of the latent hardener is 6: 1 to 1: 1, 5: 1 to 2: 1, preferably 4: 1 to 2: 1.

In said composition it is further preferred if the weight ratio between the total weight of the at least one plasticizers PL and the total weight of the acrylate polymer AP ranges from 1: 10 to 20: 10, preferably from 2: 10 to 15: 10, from 2: 10 to 15: 10, from 5: 10 to 15: 10; from 5: 10 to 10: 10, from 6: 10 to 10: 10, and most preferably from 8: 10 to 10: 10.

It can be further advantageous if the preferred composition above consists of more than 80%by weight, preferably more than 90%by weight, in particular more than 95%by weight, particularly preferably more than 98%by weight, most preferably more than 99%by weight -%, of the aforementioned components, based on the total weight of the composition

The compositions according to the present invention can be produced by mixing the components in any suitable mixing apparatus, for example in a dispersion mixer, planetary mixer, double screw mixer, continuous mixer, extruder, or dual screw extruder.

The compositions according to the present invention obtained by using the process as described above are storage stable at normal storage conditions. The term “storage stable” refers in the present disclosure to materials, which can be stored at specified storage conditions for long periods of time, such as at least one month, in particular at least 3 months, without any significant changes in the application properties of the material. The “typical storage conditions” refer here to temperatures of not more than 60 ℃, in particular not more than 50 ℃.

Another subject of the present invention is a method for providing sealing to a structure of a manufactured article, preferably an automotive vehicle, the method comprising steps of:

i) Providing a composition according to the present invention between a first member and a second member of the structure, both first and second members having outwardly and inwardly facing surfaces,

ii) Forming a weld connecting the first member to the second member such that at least a portion of the composition is displaced,

iii) Bringing the welded structure obtained in step ii) into contact with a CED coating solution, in particular at a temperature from 20 and 80 ℃, in particular from 20 -50 ℃; preferably from 20 -40 ℃., in particular for 1-15 min, preferably for 1-5 min, and

iv) heating the structure to a temperature of 140-220 ℃, in particular 140-200 ℃, preferably from 160-190 ℃, in particular for 10-60 min, particularly preferably for 20-45 min.

Preferably the steps i) to iv) are performed in chronological order starting from step i) .

The weld connecting the first and second members can be formed using any suitable welding techniques, such as electrical resistance welding or spot welding.

Preferably, step ii) comprises steps of:

i') Contacting the outwardly facing surface of the first member with a first electrode and contacting the outwardly facing surface of the second member with a second electrode and

ii') Inducing an electric current to flow between the first and second electrodes to form a weld connecting the first and second members.

Preferably, the first and second electrodes are contacted with the respective outwardly facing surfaces of the first and second members such that at least a portion of the first member and at least a portion of the second member are located between the electrodes.

In a typical weld operation, the electrodes and consequently the portions of the members are then moved towards each other, which results in partial displacement of the composition. The electrodes can be moved until the portions of the members contact each other or until the distance between the portions is small enough for forming a weld. Electrical current is then induced between the electrodes, which results in formation of one or more welds between the first and second member. The resulting weld (s) is typically at least partially surrounded by the composition.

During step iv) the curing of the composition is obtained by the diffusion of the plasticizer PL into the dispersed acrylate polymer AP, thereby causing the composition to plasticize. When cooling, the composition gel into a dimensionally stable system.

The first member of the structure can consist of the same or a different material as the second member.

The application in which at least one material is a metal is preferred. The use of the same or different metals, in particular in body-in-white construction in the automotive industry, is regarded as a particularly preferred use. The preferred metals are steel, in particular electrolytically galvanized, hot-dip galvanized, oiled steel, bonazinc-coated steel, and subsequently phosphated steel, and aluminum, in particular in the variants typically occurring in automobile construction.

It is therefore preferred that first member of the structure and /or the second member of the structure is a metal.

It is also advantageous if there is no curing, especially no complete curing, of the applied composition before step iii) , in particular no curing by heating the composition to a temperature of 140-220 ℃., in particular for 10-60 min, particularly preferably for 20-45 min.

Step iii) is typically carried out by immersing in a CEDC bath containing a CED coating solution. Preferred coating solutions are described, for example, as cathodic electrodeposition material in the

Chemie Lexikon, online version, Georg Thieme Verlag, accessed on December 14, 2018. Step iv) is typically carried out in a CEDC oven. The composition cures by heating the composition in step iv) .

Such a method for providing sealing to a structure of a manufactured article results in an article, which represents a further aspect of the present invention. Such an article is preferably a vehicle or part of a vehicle, preferably an automotive vehicle.

According to one or more embodiments, in case the composition contains a blowing agent BA, upon activation, has a volume increase compared to its original unexpanded volume of 25 –500 %, preferably 50 –400 %, more preferably 75 –350 %, even more preferably 100 –350 %, whereby the volume increase is determined using the DIN EN ISO 1183 method of density measurement (Archimedes principle) in deionised water in combination with sample mass determined by a precision balance.

Examples

Preparation of the compositions

The reference compositions R1 -R21 and the compositions E1-E12 according to the invention were produced in accordance with the information in tables 1 -4.

With the exception of the composition R1, the amount in %by weight based on the total composition (wt. -%) of “Nc CB” , KA-1 or KA2 listed in Table 2 was added for each composition and in return the corresponding amount of kaolin powder was removed. For example, 2 wt. -%of the product KA-1 was used in the composition E1 and only 28.1%by weight of kaolin was added accordingly.

Raw material	(wt. -%)
DINP	29
Kaolin powder (filler)	30.1
Fumed silica	1.3
Organoclay (rheological additive)	1.2
Naftenic Oil (process oil)	3.7
Mixture CaCO3 and CaO (filler)	5
Liquid epoxy resin (Bisphenol-A-diglycidylether)	2.8
Latent curing agent, dicyandiamide	0.9
Kane Ace UC506	26
Total (wt. -%)	100

Table 1, raw materials used for composition R1 –R21 and E1 -E12

Table 2, raw materials used for “Nc CB” , KA-1 or KA2

Test methods:

CED coating in uncured state (E-coating b. c. = “before curing” )

For coating with a CED coating, the respective composition was applied at room temperature as a round bead (width 15 mm, height 5 mm) to an oiled sheet (200 x 25 mm, electrolytically galvanized, DC-04) . The sample was then conditioned in the uncured state for 1 hour at room temperature.

The test specimens were then degreased with an alkaline cleaner prior to CED coating (Aclean 02.21 cleaning bath from Chemetall, 5 minutes at 60 ℃) .

Then the specimen was rinsed under running water at 23 ℃. for 20 seconds. The test specimen was then coated.

The CED bath contained the Cathogard 500 KTL coating solution (from BASF Coatings Münster) . The coating time was 5 minutes at a voltage of 280 V and a temperature of the CED solution of 28 ℃.

After the CED treatment had been carried out, the beads were cured for 35 min at 175 ℃. and the quality of the bead's CED coating was assessed on the following scale:

1: bead not coated and gap not filled with e-coating

2: bead not coated but gap partially filled with e-coating

3: bead not coated, gap filled with e-coating

4: bead partially coated at the edges

5: bead is coated at the edges

6: bead partially coated

7: bead is completely coated but the ground shimmers through

8: bead completely coated with faint streaks

9: bead completely coated without imperfections

Samples with a value of 6 to 9 were described as sufficiently coated.

CED coating in cured state (E-coating a. c. = “after curing” )

For coating with a CED coating, the respective composition was applied at room temperature as a round bead (width 15 mm, height 5 mm) to an oiled sheet (200 x 25 mm, electrolytically galvanized, DC-04) . The sample was then conditioned in the uncured state for 1 hour at room temperature. Then the sample was cured for 22 min at a temperature of 160 ℃. After conditioning of the cured sample for 30 min at a temperature of 23 ℃, the test specimens were then degreased and all subsequent steps were performed as described before for “CED coating in uncured state” .

Viscosity

The viscosity was measured oscillographically using a rheometer with a heated plate (MCR 201, AntonPaar) at 25 ℃ (gap 1000 μm, measuring plate diameter: 25 mm (plate /plate) , deformation 0.01 at 5 Hz, heating rate 10 ℃/min) .

Claims

A composition comprising:

a) at least one acrylate polymer AP;

b) at least one epoxy resin A having on average more than one epoxide group per molecule;

c) at least one latent hardener for epoxy resins;

d) at least one plasticizer PL; and

e) at least one electrically conductive carbon allotrope KA selected from the list consisting of carbon blacks (KA-1) and graphenes (KA-2) ,

the amount of carbon blacks (KA-1) being 2 -9 wt. -%, and/or the amount of graphenes (KA-2) being 4 –9 wt. -%, based on the total weight of the composition, wherein the total amount of electrically conductive carbon allotrope KA is from 2 -9 wt. -%, based on the total weight of the composition.
The composition according to claim 1, wherein the amount of carbon blacks (KA-1) is from 2 -8 wt. -%, 2.5 –7.5 wt. -%, 3 -7 wt. -%, 3.5 -6 wt. -%, preferably 3.5 –5.5 wt. -%, more preferably 3.5 –5 wt. -%, most preferably 3.5 –4.5 wt. -%, based on the total weight of the composition.
The composition according to any one of previous claims, wherein the amount of graphenes (KA-2) is from 4.5 -8 wt. -%, 4.5 –7.5 wt. -%, preferably 5 –7.5 wt. -%, more preferably 5 -7 wt. -%, most preferably 5 –6, based on the total weight of the composition.
The composition according to any one of previous claims, wherein the amount of at least one acrylate polymer AP is 5 –40 wt. -%, 10 –40 wt. -%, 12.5 –40 wt. -%, more preferably 15 –35 wt. -%, even more preferably 17.5 –32.5 wt. -%, most preferably 20 –30 wt. -%, based on the total weight of the composition.
The composition according to any one of previous claims, wherein the at least one acrylate polymer AP is selected from the list consisting of polymers of methyl acrylate, ethyl acrylate methyl methacrylate, propyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and any copolymers thereof.
The composition according to any one of previous claims, wherein the fraction of the epoxy resin A having on average more than one epoxide group per molecule is preferably from 0.5 -15 wt. -%, 1 -10 wt. -%, 1.5 -7.5 wt. -%, 1.5 -5 wt. -%, more preferably 2 -4 wt. -%, based on the total weight of the composition.
The composition according to any one of previous claims, wherein the latent hardener is selected from the group consisting of dicyandiamide, guanamines, guanidines, aminoguanidines and derivatives thereof, substituted ureas, imidazoles and amine complexes, preferably dicyandiamide.
The composition according to any one of previous claims, wherein the weight ratio of the total amount of the at least one epoxy resin A having on average more than one epoxide group per molecule to the total amount of the latent hardener is 6: 1 to 1: 1, 5: 1 to 2: 1, preferably 4: 1 to 2: 1.
The composition according to any one of previous claims, wherein the at least one plasticizer PL is a phthalate, more preferably diisononyl phthalate (DINP) or dioctyl phthalate (DOP) , most preferred DINP.
The composition according to any one of previous claims, wherein the composition comprises 5 –50 wt. -%, 10 –40 wt. -%, preferably 12.5 –40 wt. -%, more preferably 15 –35 wt. -%, even more preferably 17.5 –32.5 wt. -%, most preferably 20 –30 wt. -%, based on the total weight of the composition, of the at least one plasticizer PL.
The composition according to any one of previous claims, wherein the composition comprises 5 –50 wt. -%, 10 –40 wt. -%, 12.5 –40 wt. -%, preferably 15 –35 wt. -%, more preferably 17.5 –32.5 wt. -%, most preferably 20 –30 wt. -%, based on the total weight of the composition, of the at least one plasticizer PL.
The composition according to any one of previous claims, wherein the weight ratio between the total weight of the at least one plasticizers PL and the total weight of the acrylate polymer AP ranges from 1: 10 to 20: 10, preferably from 2: 10 to 15: 10, from 2: 10 to 15: 10, from 5: 10 to 15: 10; from 5: 10 to 10: 10, from 6: 10 to 10: 10, and most preferably from 8: 10 to 10: 10.
The composition according to any one of previous claims, wherein the composition has a viscosity at 25 ℃ of 300-5000 Pa *s, 500-4000 Pa *s, 750-3500 Pa *s preferably 1000-3000 Pa *s, in particular 1500-2500 Pa *s, preferably determined oscillographically by a rheometer with a heated plate (MCR 201, AntonPaar) (gap 1000 μm, measuring plate diameter: 25 mm (plate /plate) , deformation 0.01 at 5 Hz, heating rate 10 ℃ /min) .
A method for providing sealing to a structure of a manufactured article, preferably an automotive vehicle, the method comprising steps of:

i) Providing a composition according to any of claims 1-13 between a first member and a second member of the structure, both first and second members having outwardly and inwardly facing surfaces,

ii) Forming a weld connecting the first member to the second member such that at least a portion of the composition is displaced,

iii) Bringing the welded structure obtained in step ii) into contact with a CED coating solution, in particular at a temperature from 20 and 80 ℃, in particular from 20 and 50 ℃; preferably from 20 and 40 ℃, in particular for 1-15 min, more preferably for 1-5 min, and heating the structure to a temperature of 140-220 ℃, in particular 140-200 ℃, preferably 160-190 ℃, in particular for 10-60 min, preferably for 20-45 min.
The method according to claim 14, wherein there is no curing, especially no complete curing, of the applied composition before step iii) , in particular no curing by heating the composition to a temperature of 140-220 ℃, in particular for 10-60 min, more particularly for 20-45 min.