Flame-retardant adhesive composition

Abstract

The invention relates to an adhesive composition comprising at least one flame retardant and to an adhesive tape comprising the adhesive composition. The adhesive composition comprises at least one flame retardant of formula (I), wherein A is selected from residues containing at least one substituted or unsubstituted aromatic group; and wherein R1 and R2 independently of one another are identical or different and are selected from hydrogen atoms and hydrocarbon-containing residues which may carry heteroatoms.

Description

[0001] tesa SE Norderstedt

[0002] Flame-retardant adhesive composition

[0003] The invention relates to an adhesive composition comprising at least one flame retardant and to an adhesive tape comprising the adhesive composition.

[0004] In many areas of technology, for example in the construction industry and in the automotive and aircraft industry, increasingly demanding requirements are being imposed with regard to the flame retardancy of installed parts. Various relevant test methods have been developed to meet specific requirements. For example, components and accessories used in aircraft construction must pass a so-called vertical Bunsen burner test. This also applies to adhesive tapes that are used in aircraft construction, for example, for securing insulation packages or floor coverings. Accordingly, flame-retarded pressure-sensitive adhesive compositions (PSAs) are required for such adhesive tapes.

[0005] However, it has emerged that the formulation of pressure-sensitive adhesive compositions with good flame retardancy qualities is not without problems. Flame retardants used often lead to massive losses in adhesion and cohesion, this being in turn manifested in significantly poorer peel adhesion and shear strength values. There is therefore generally a conflict of objectives between the required adhesive performance of the PSAs on the one hand and the likewise required flame retardancy qualities on the other.

[0006] In addition, many flame-retarded PSA compositions exhibit severe emission of smoke in the event of a fire, which, especially in the case of halogenated flame retardants, entails toxic gases and is therefore also undesirable.

[0007] EP 3822329 A1 proposes, for resolving the conflicts of objectives, a pressure-sensitive adhesive composition containing an aromatic organophosphorus compound, wherein the aromatic organophosphorus compound is more particularly triphenyl phosphate, resorcinol bis(diphenyl phosphate) or bisphenol A bis(diphenyl phosphate).

[0008] WO 2012060895 A1 discloses a pressure-sensitive adhesive composition which is said to be sufficiently flame retardant, the amount of flame retardant being as low as possible so as to avoid an unacceptable reduction in the performance of the adhesive composition. For this purpose, the PSA of WO 2012060895 A1 contains at least one cyclic phosphonate ester. In addition to the conflicts of objectives addressed above, it is also desirable for many applications if the adhesive composition has a relatively high stability to heat and humidity and is still flame retardant even after storage under hot and humid conditions.

[0009] The present invention is therefore based on the object of providing an adhesive composition which has very good flame retardancy qualities even after storage under hot and humid conditions. Furthermore, the present invention is also based on the object of providing an adhesive composition which has very good flame retardancy qualities as well as a long shelf life in aqueous media. At the same time, the adhesive properties of the flame-retardant adhesive should not be significantly poorer than those of the underlying base adhesive composition without the flame retardant treatment.

[0010] The object is solved in accordance with the invention by the adhesive composition according to Claim 1.

[0011] The adhesive composition of the invention comprises at least one flame retardant of formula I): wherein A is selected from residues containing at least one substituted or unsubstituted aromatic group; and wherein R1and R2independently of one another are identical or different and are selected from hydrogen atoms and hydrocarbon-containing residues which may carry heteroatoms.

[0012] It has surprisingly been found that an adhesive composition comprising at least one flame retardant of formula I), i.e. a cyclic phosphonate having at least one aromatic group, still has very good flame retardancy qualities compared to the prior art even after storage under hot and humid conditions.

[0013] Within the scope of the invention, it has also been possible to identify particularly suitable adhesive compositions. Such and further embodiments which are hereinafter designated as preferred are combined in more preferred embodiments with features of other embodiments designated as preferred. Especially preferred are therefore combinations of two or more of the embodiments described below as more preferred. Also preferred are embodiments in which a feature of one embodiment which is designated in any degree as preferred is combined with one or more further features of other embodiments which are designated in any degree as preferred.

[0014] Features of preferred adhesive compositions and adhesive tapes and also uses of the adhesives result from the features of preferred adhesive compositions.

[0015] The expression "hot and humid conditions" is understood in the context of the present invention to mean in particular conditions which include a relative humidity of more than 60% and an ambient temperature of more than 25°C.

[0016] In the context of the present invention, a temperature of 85°C and a relative humidity of 85% are used for the tests as a standardized ambient climate.

[0017] In particular, "storage under hot and humid conditions" means that the materials or articles considered are stored for a period of more than one day at a relative humidity of more than 60% and an ambient temperature of more than 25°C. Long storage times, such as in particular more than 100 hours, for example 500 or 1000 hours, are particularly significant in this context.

[0018] According to the invention, the adhesive composition comprises at least one flame retardant of formula I): wherein A is selected from residues containing at least one substituted or unsubstituted aromatic group; and wherein R1and R2independently of one another are identical or different and are selected from hydrogen atoms and hydrocarbon-containing residues which may carry heteroatoms.

[0019] It is essential to the invention that the flame retardant of formula I) contains at least one residue A which contains at least one aromatic group. The residue A is in this case, according to preferred embodiments, a purely aromatic residue or a mixed aliphatic-aromatic residue, i.e., for example, an aliphatic hydrocarbon group to which in turn an aromatic group is bonded. Preferably, the residue A is a mixed aliphatic-aromatic residue, wherein the aromatic group is bonded to the phosphorus atom not directly but via an alkyl bridge, which is preferably a methylene unit, -(CH2)-.

[0020] The residues R1and R2are selected from hydrogen atoms and hydrocarbon-containing residues which may carry heteroatoms.

[0021] Preferably, R1and R2are hydrocarbon-containing residues which carry heteroatoms.

[0022] Preferably, R1and R2are bridged to one another to form a common hydrocarbon-containing heterocycle, as outlined in formula la).

[0023] Preferably, the residues R1and R2are each bonded to the remaining part of the molecule via a carbon atom.

[0024] Preferably, the heterocycle comprises oxygen atoms and / or phosphorus atoms in addition to carbon atoms.

[0025] The left-hand part of the molecule in formula I) and la), to which the central carbon atom is bonded, is one example of such a hydrocarbon-containing heterocycle.

[0026] More preferably, the at least one flame retardant thus contains a structure of formula II): wherein A and Ai independently of one another are identical or different and are selected from residues containing at least one substituted or unsubstituted aromatic group.

[0027] The residues A and Ai are independently of one another identical or different, wherein the above observations regarding A apply to Ai. The residues A and Ai may optionally carry one or more substituents on the aromatic component. The substituents may in principle be any kind of substituents, more particularly and preferably halogen groups, alkyl groups, preferably Ci-Ce alkyl groups, OH groups. In particular, those substituents which are synthetically attached to the aromatic ring system according to the synthesis route and / or starting substances selected are preferably also included as substituents according to the invention.

[0028] Preferably, the residues A and Ai in formula II) are identical.

[0029] Preferably, the residues A in formula I) or A and Ai in formula II) are selected from phenyl and benzyl groups.

[0030] More preferably, A or A and Ai are benzyl groups.

[0031] More preferably, the flame retardant in the adhesive composition of the invention comprises at least the compound of formula III):

[0032] With the compound of formula III) as flame retardant in the adhesive composition of the invention, particularly good flame retardancy qualities are obtained even after storage under hot and humid conditions. At the same time, the adhesive composition herewith exhibits very good adhesive properties.

[0033] According to preferred embodiments, the adhesive composition of the present invention is a solvent-borne adhesive composition. According to other preferred embodiments, the adhesive composition of the present invention is a water-borne adhesive composition.

[0034] It can be readily understood by the skilled person that the weight percentages referred throughout the patent specification in the context of water-borne adhesive compositions of the present invention are specified in relation to the total solids content of the water-borne adhesive compositions. For example, the skilled person can readily understand that 1% by weight of component X based on the total mass of a water-borne adhesive composition refers to 1% by weight of component X based on the total solids content of the water-borne adhesive composition.

[0035] Preferably, the adhesive composition contains 0.5% to 40% by weight, based on the total mass of the adhesive composition, of at least one flame retardant of formula I), preferably of formula

[0036] II), more preferably of formula III).

[0037] Surprisingly, it has been found that even with small amounts of the flame retardant, such as 1.5% by weight, for example, very good flame retardancy qualities are achieved even after storage under hot and humid conditions.

[0038] With a comparatively high amount as well, such as 25% by weight, excellent properties are achieved.

[0039] However, if the amount of flame retardants is too high, the adhesive composition may not be economical.

[0040] For the amounts of flame retardant discussed, what is meant in each case is the total amount of flame retardant of formula I) in the adhesive composition.

[0041] Preferably, the adhesive composition contains 1 % to 40% by weight, more preferably 1 .3% to 40% by weight, based on the total mass of the adhesive composition, of at least one flame retardant of formula I), preferably of formula II), more preferably of formula III).

[0042] In further preferred embodiments, the adhesive composition contains 0.5% to 25% by weight, more preferably 1 % to 20% by weight, based on the total mass of the adhesive composition, of at least one flame retardant of formula I), preferably of formula II), more preferably of formula

[0043] III).

[0044] Preferably in turn, the amount of the at least one flame retardant of formula I), preferably of formula II), more preferably of formula III), is 1% to 30% by weight, more preferably 1% to 20% by weight, more particularly 1 .3% to 30% by weight, more preferably 1 .3% to 20% by weight. Especially preferably, the amount is 1 .5% to 5% by weight.

[0045] According to particularly advantageous embodiments of the invention, the adhesive composition contains 0.5% to 2.5% by weight, more preferably 1% to 2.5% by weight, more particularly 1 .3% to 2.5% by weight, of the at least one flame retardant of formula I), preferably of formula II), more preferably of formula III).

[0046] According to preferred embodiments, the solvent-borne adhesive composition of the present invention contains 1% to 30% by weight, more preferably 1% to 20% by weight, more particularly 1.3% to 30% by weight, more preferably 1.3% to 20% by weight, especially preferably 1.5% to 5% by weight, of at least one flame retardant of formula I), preferably of formula II), more preferably of formula III), based on the total mass of the solvent-borne adhesive composition. According to further preferred embodiments, the solvent-borne adhesive composition of the present invention contains 0.5% to 2.5% by weight, more preferably 1% to 2.5% by weight, more particularly 1.3% to 2.5% by weight, of the at least one flame retardant of formula I), preferably of formula II), more preferably of formula III), based on the total mass of the solvent- borne adhesive composition.

[0047] According to even further preferred embodiments, the water-borne adhesive composition of the present invention contains 1% to 40% by weight, more preferably 1% to 30% by weight, more particularly 1 .5% to 30% by weight, more preferably 1 .5% to 20% by weight, even more preferably 5% to 20% by weight, especially preferably 10% to 20% by weight, based in each case on the total mass of the water-borne adhesive composition, preferably based in each case on the total solids content of the water-borne adhesive composition, of at least one flame retardant of formula I), preferably of formula II), more preferably of formula III).

[0048] Achieved herewith are very good flame retardancy qualities even after storage under hot and humid conditions, while at the same time the shear strength and adhesive properties of the adhesive composition before and after storage under hot and humid conditions are not adversely affected.

[0049] Preferably, the at least one flame retardant is halogen-free or contains only very small amounts of halogen, in particular from 0 to 1500 ppm, preferably 0 to 400 ppm, based on the weight of the respective flame retardant.

[0050] Preferably, the entire adhesive composition has a halogen content of 0 to 600 ppm, more preferably from 0 to 450 ppm, especially preferably from 0 to 300 ppm, in turn preferably from 0 to 160 ppm, in turn more preferably from 0 to 120 ppm, in turn especially preferably from 0 to 80 ppm, in turn especially preferably from 0 to 20 ppm.

[0051] The adhesive composition may in principle be any adhesive composition in which flame retardancy qualities are desired or required and into which the flame retardant of formula I), preferably of formula II), more preferably of formula III), can be mixed.

[0052] According to preferred embodiments of the invention, the adhesive composition is a pressuresensitive adhesive composition.

[0053] With the present invention, it has been possible in particular to provide a pressure-sensitive adhesive composition which has very good flame retardancy qualities even after storage under hot and humid conditions. According to the present invention, a pressure-sensitive adhesive composition presently is, as is generally customary, a substance which - especially at room temperature - is permanently tacky and adhesive-capable. Characteristic of a pressure-sensitive adhesive composition is that it can be applied by pressure to a substrate and remains stuck there, with the pressure to be applied and the duration of exposure to this pressure not being defined in more detail. In some cases, depending on the exact nature of the pressure-sensitive adhesive, the temperature and the humidity, and on the substrate, the effect of a short-term, minimal pressure that does not go beyond a slight contact for a short moment is sufficient to achieve the adhesion effect; in other cases, a longer-term duration of exposure to a high pressure may also be necessary.

[0054] Pressure-sensitive adhesive compositions have special, characteristic viscoelastic properties, which lead to the permanent tack and adhesive capability. It is a characteristic feature of these that, when they are mechanically deformed, the result is both viscous flow processes and the development of elastic resilience forces. The two processes are in a certain proportion to each other, depending not only on the exact composition, the structure and the degree of crosslinking of the adhesive, but also on the speed and duration of the deformation and on the temperature.

[0055] The viscous flow component is necessary for achievement of adhesion. Only the viscous components, caused by macromolecules with relatively high mobility, allow good wetting and good flow onto the substrate to be bonded. A high proportion of viscous flow leads to high pressure-sensitive adhesiveness (also referred to as tack or surface tack) and hence often also to a high bonding force. Highly crosslinked systems, or polymers that are crystalline or solidify in vitreous form, generally have at least only low pressure-sensitive adhesion, if any, for lack of free-flowing components.

[0056] The elastic resilience force components are needed for achievement of cohesion. They are caused, for example, by very long-chain and entangled macromolecules that are crosslinked physically or chemically, and enable transmission of the forces that attack an adhesive bond. They have the effect that an adhesive bond can withstand a sustained stress acting thereon, for example in the form of a sustained shear stress, to a sufficient degree over a prolonged period of time.

[0057] For a more precise description and quantification of the measure of elastic and viscous components as well as the ratio of the components to each other, the variables of storage modulus (G') and loss modulus (G"), which can be determined by means of dynamic mechanical analysis (DMA, according to DIN EN ISO 6721 ), can be used. G' is a measure of the elastic component, G" a measure of the viscous component of a substance. Both parameters are dependent on deformation frequency and temperature.

[0058] The parameters can be ascertained with the aid of a rheometer. The material to be examined is subjected here to a sinusoidally oscillating shear stress, for example in a plate-plate arrangement. In the case of shear stress-controlled devices, deformation as a function of time and the time delay of this deformation are measured with respect to the onset of shear stress. This time delay is referred to as the phase angle 5.

[0059] The storage modulus G' is defined as follows:

[0060] G' = (T / Y) • cos(b) (T = shear stress, y = deformation, 5 = phase angle = phase shift between shear stress vector and deformation vector).

[0061] The definition of the loss modulus G" is:

[0062] G" = (T / Y) • sin(b) (T = shear stress, y = deformation, 5 = phase angle = phase shift between shear stress vector and deformation vector).

[0063] A substance is generally considered to be pressure-sensitive adhesive and is defined as pressure-sensitive adhesive for the purposes of the invention if at room temperature, here by definition at 23°C, in the deformation frequency range from 10° to 101rad / sec, G' is at least partly in the range from 103to 107Pa and if G" is also at least partly in this range. "Partly" means that at least one portion of the G' curve is within the window spanned by the deformation frequency range from inclusively 10° to inclusively 101rad / sec (abscissa) and the range of the G' values from inclusively 103to inclusively 107Pa (ordinate). For G", this applies correspondingly.

[0064] Preferably, the pressure-sensitive adhesive composition in the deformation frequency range from 10° to 101rad / sec at 23°C has a storage modulus G' and a loss modulus G" in the range from 103to 107Pa, determined according to DIN EN ISO 6721 .

[0065] The adhesive composition can in principle be based on any chemical systems, more particularly polymer systems, which are known to the skilled person.

[0066] Preferably, the adhesive composition comprises at least one poly(meth)acrylate.

[0067] A "poly(meth)acrylate" means a polymer which is obtainable by polymerization, for example radical polymerization, of acrylic and / or methacrylic monomers and optionally other copolymerizable monomers. In particular, a "poly(meth)acrylate" means a polymer whose monomer base consists of at least 50% by weight of acrylic acid, methacrylic acid, acrylic acid esters and / or methacrylic acid esters, wherein acrylic acid esters and / or methacrylic acid esters are present at least proportionally, preferably to an extent of at least 30% by weight, based on the total monomer base of the polymer in question.

[0068] A pressure-sensitive adhesive composition of the invention preferably comprises at least one poly(meth)acrylate, and so can comprise one or more poly(meth)acrylates. The terms "at least one" or "one or more" or else "exactly one" refer here in a manner customary in the sector to the chemical nature of the corresponding compounds and not to their amount of substance. This also applies to the monomer composition of the poly(meth)acrylate.

[0069] For example, the monomer composition as a monomer may exclusively comprise n-butyl acrylate, which would mean that the monomer composition comprises a multiplicity of n-butyl acrylate molecules.

[0070] Preferably, the total amount of poly(meth)acrylates is 40% to 99.5% by weight, based on the total mass of the adhesive composition.

[0071] More preferably, the total amount of poly(meth)acrylates is 50% to 99.5% by weight.

[0072] According to more preferred embodiments of the invention, the total amount of poly(meth)acrylates is 50% to 75% by weight, preferably 60% to 70% by weight, based on the total mass of the adhesive composition.

[0073] According to preferred embodiments, the total amount of poly(meth)acrylates of the solvent- borne adhesive composition of the present invention is 40% to 99.5% by weight, based on the total mass of the solvent-borne adhesive composition.

[0074] More preferably, the total amount of poly(meth)acrylates of the solvent-borne adhesive composition of the present invention is 50% to 99.5% by weight, based on the total mass of the solvent-borne adhesive composition.

[0075] According to more preferred embodiments of the invention, the total amount of poly(meth)acrylates of the solvent-borne adhesive composition is 50% to 75% by weight, preferably 60% to 70% by weight, based on the total mass of the solvent-borne adhesive composition.

[0076] According to other preferred embodiments, the total amount of poly(meth)acrylates of the water-borne adhesive composition of the present invention is 40% to 99.5% by weight, based on the total mass of the water-borne adhesive composition, preferably based on the total solids content of the water-borne adhesive composition.

[0077] More preferably, the total amount of poly(meth)acrylates of the water-borne adhesive composition of the present invention is 50% to 99.5% by weight, based on the total mass of the water-borne adhesive composition, preferably based on the total solids content of the water-borne adhesive composition.

[0078] According to more preferred embodiments of the invention, the total amount of poly(meth)acrylates of the water-borne adhesive composition is 60% to 99.5% by weight, more preferably 75% to 90% by weight, based in each case on the total mass of the water-borne adhesive composition, preferably based in each case on the total solids content of the waterborne adhesive composition.

[0079] It may contain one (single) poly(meth)acrylate or more poly(meth)acrylates; the plural expression "poly(meth)acrylates" therefore includes - also in the continuation of the present description - in its meaning, just like the expression "total amount", both the presence of a single poly(meth)acrylate and the presence of a plurality of poly(meth)acrylates.

[0080] The poly(meth)acrylate(s) may in principle be any poly(meth)acrylates which can preferably form a pressure-sensitive adhesive composition and into which the flame retardant of formula I), preferably of formula II), more preferably of formula III) can be mixed.

[0081] According to preferred embodiments of the invention, the poly(meth)acrylates present can be produced by polymerization of a monomer composition comprising one or more monomers selected from the group consisting of ethyl acrylate, n-butyl acrylate, isobutyl acrylate, tertbutyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-heptyl acrylate, n-heptyl acrylate, 2- ethylhexyl acrylate, 2-octyl acrylate, n-octyl acrylate, isooctyl acrylate, n-nonyl acrylate, isononyl acrylate, n-decyl acrylate, isodecyl acrylate, 2-[[(butylamino)carbonyl]oxy]ethyl acrylate, 2-cyanoethyl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, phenoxyethyl acrylate, isostearyl acrylate, docosyl acrylate, 2-[2-(2-methoxyethoxy)ethoxy]ethyl acrylate, isobornyl acrylate, norbornyl acrylate, benzyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, cyclohexyl acrylate, 1 -acryloyloxy-3- hydroxyadamantane,

[0082] 4-[(6-acryloyloxy)hexyloxy]-4'-cyanobiphenyl, N-succinimidyl acrylate,

[0083] 1 -ethylcyclopentyl acrylate, N-tert-octylacrylamide, N-tert-butylacrylamide, dimethylacrylamide, diethylacrylamide, N-isopropylacrylamide, N-hydroxyethylacrylamide, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N-[3-

[0084] (dimethylamino)propyl]acrylamide, diacetoneacrylamide, N-(butoxymethyl)acrylamide, N-phenylacrylamide, N-[2-(dimethylamino)ethyl]acrylamide, N-[2-(diethylamino)ethyl]acrylamide, methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, isobornyl methacrylate, glycerol formal methacrylate, 2- dimethylaminoethyl methacrylate, phenoxyethyl methacrylate, 9-anthrylmethyl methacrylate, 2-ethyl-2-adamantyl methacrylate, 2-(acetoacetyloxy)ethyl methacrylate, 2-isopropyl-2- methacryloyloxyadamantane, isopropyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, furfuryl methacrylate, 2-methacryloyloxy-2-methyladamantane, 2-morpholinoethyl methacrylate, phenyl methacrylate, N-succinimidyl methacrylate,

[0085] 2-(tert-butylamino)ethyl methacrylate, 2-cyclohexylpropan-2-yl methacrylate,

[0086] 1 -adamantyl methacrylate, 1 -methylcyclopentyl methacrylate,

[0087] 3-dimethylaminopropylmethacrylamide, N-tert-butylmethacrylamide, N-(methoxymethyl)methacrylamide, N,N-dimethylmethacrylamide, methacrylamide, N-phenylmethacrylamide, N,N-dimethylmethacrylamide, N-isopropylmethacrylamide, N-vinylformamide, N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylcarbazole, N-vinylimidazole, vinylmethyloxazolidinone, N-vinyl-N-methylacetamide, hydroxyethyl acrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxy-3-phenoxypropyl acrylates, hydroxyethyl methacrylate, hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxy-3- phenoxypropyl methacrylate, 4-hydroxyethylacrylamide, acrylic acid, methacrylic acid,

[0088] 2-acryloyloxyethyl succinate, methacryloxyethyl succinate, sulfoethyl methacrylate, methacrylamide, glycidyl acrylate, glycidyl methacrylate, 3,4-epoxycyclohexylmethyl acrylate, 3,4-epoxycyclohexylmethyl methacrylate, 4-hydroxybutyl acrylate glycidyl ether,

[0089] 4-hydroxybutyl methacrylate glycidyl ether, isocyanatoethyl acrylate, isocyanatoethyl methacrylate, 2-[2-(methacryloyloxy)ethyloxy]ethyl isocyanate, 2-[2- (acryloyloxy)ethyloxy]ethyl isocyanate and a,a-dimethyl-m-isopropenylbenzyl isocyanate.

[0090] According to preferred embodiments, the poly(meth)acrylates present can be produced by polymerization of a monomer composition which comprises as monomers a) (meth)acrylate monomers comprising functional groups, the functional groups being selected in particular from hydroxyl groups, amine groups and carboxyl groups; and b) unfunctionalized monomers whose homopolymer has a glass transition temperature Tgaccording to DSC of more than 50°C; and c) unfunctionalized monomers whose homopolymer has a glass transition temperature Tgaccording to DSC of less than 50°C.

[0091] According to preferred embodiments, the poly(meth)acrylates present can be produced by polymerization of a monomer composition which comprises as monomers a) at least one monomer selected from the group consisting of acrylic acid, 2-hydroxyethyl methacrylate and 4-hydroxybutyl acrylate; and b) at least one monomer selected from the group consisting of methyl acrylate, methyl methacrylate, isobornyl acrylate, acrylamide; and c) at least one monomer selected from the group consisting of 2-ethylhexyl acrylate, n-butyl acrylate, 2-octyl acrylate, n-heptyl acrylate.

[0092] According to preferred embodiments, the poly(meth)acrylates present in solvent-borne adhesive compositions of the present invention are produced by polymerization of a monomer composition which comprises as monomers a) at least one monomer selected from the group consisting of acrylic acid, 2-hydroxyethyl methacrylate and 4-hydroxybutyl acrylate; and b) at least one monomer selected from the group consisting of methyl acrylate, methyl methacrylate, isobornyl acrylate, acrylamide; and c) at least one monomer selected from the group consisting of 2-ethylhexyl acrylate, n-butyl acrylate, 2-octyl acrylate, n-heptyl acrylate.

[0093] According to further preferred embodiments, the poly(meth)acrylates present in water-borne adhesive compositions of the present invention are produced by polymerization of a monomer composition which comprises as monomers a) at least one monomer selected from the group consisting of methacrylic acid, acrylic acid, 2-hydroxyethyl methacrylate and 4-hydroxybutyl acrylate; and b) at least one monomer selected from the group consisting of methyl acrylate, methyl methacrylate, isobornyl acrylate, acrylamide; and c) at least one monomer selected from the group consisting of 2-ethylhexyl acrylate, n-butyl acrylate, 2-octyl acrylate, n-heptyl acrylate.

[0094] According to more preferred embodiments, the poly(meth)acrylates present can be produced by polymerization of a monomer composition containing acrylic acid, methyl acrylate and 2- ethylhexyl acrylate as monomers.

[0095] According to preferred embodiments, the poly(meth)acrylates present in solvent-borne adhesive compositions of the present invention are produced by polymerization of a monomer composition containing acrylic acid, methyl acrylate and 2-ethylhexyl acrylate as monomers.

[0096] According to further preferred embodiments, the poly(meth)acrylates present in water-borne adhesive compositions of the present invention are produced by polymerization of a monomer composition containing n-butyl acrylate, acrylic acid, methyl methacrylate, and 2-hydroxyethyl methacrylate as monomers.

[0097] The production of the poly(meth)acrylates is preferably done by conventional radical polymerizations or controlled radical polymerizations. The poly(meth)acrylates can be produced by copolymerization of the monomers using customary polymerization initiators and optionally chain transfer agents, with polymerization at the usual temperatures in bulk, in emulsion, for example in water or liquid hydrocarbons, or in solution.

[0098] In other preferred embodiments, the poly(meth)acrylates present in water-borne adhesive compositions of the present invention are produced by emulsion polymerizations of the monomer composition described above in an aqueous dispersion medium. In particular, the poly(meth)acrylates can be produced by emulsion polymerization of the monomer composition described above using customary polymerization initiators and optionally chain transfer agents, with polymerization at the usual temperatures in water as a dispersion medium, resulting in an aqueous dispersion of poly(meth)acrylates (hereinafter known as composition P). Descriptions of the process of emulsion polymerization can be found for example in "Emulsion Polymerization and Emulsion Polymers" by Peter A. Lovell and Mohamed S. El- Aasser - Wiley-VCH 1997 - ISBN 0-471 -96746-7.

[0099] Within the aqueous dispersion of poly(meth)acrylates (composition P) of the present invention, the poly(meth)acrylates are present in the form of stable and largely homogeneously dispersed particles in a dispersion medium, preferably water. The dispersed particles may optionally be stabilized by emulsifiers or protective colloids.

[0100] In preferred embodiments of the present invention, the aqueous dispersion of poly(meth)acrylates (composition P) may be self-dispersing and can be obtained readily by emulsion polymerization, without the use of any dispersing agents.

[0101] In certain embodiments of the present invention, the aqueous dispersion of poly(meth)acrylates (composition P) may be obtained by emulsion polymerization with the use of one or more dispersing agents known to the skilled person.

[0102] In the emulsion polymerization for preparing the aqueous dispersion of poly(meth)acrylates (composition P) of the present invention, a seed dispersion may be employed. Any seed particles as known to the person skilled in the art can be used.

[0103] The seed particles may preferably be present in an amount of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of total ethylenically unsaturated monomers employed in the polymer. A person skilled in the art will understand that any range formed by any of the explicitly disclosed lower limits and upper limits is explicitly encompassed in the present specification.

[0104] The process for the preparation of the above-described aqueous dispersion of poly(meth)acrylates (composition P) can be performed at temperatures of from 0 to 130 °C, preferably of from 0 to 100 °C, particularly preferably of from 20 to 95 °C, very particularly preferably of from 40 to 90 °C, in the presence of no or one or more emulsifiers, no or one or more protective colloids and one or more initiators. Initiators which can be used when carrying out the present invention may include water-soluble and / or oil-soluble initiators which are effective for the purposes of the polymerization. Representative initiators are well known in the technical area and include, for example: azo compounds (such as, for example, AIBN, AMBN and cyanovaleric acid) and inorganic peroxy compounds, such as hydrogen peroxide, sodium, potassium and ammonium peroxydisulfate, peroxycarbonates and peroxyborates, as well as organic peroxy compounds, such as alkyl hydroperoxides, dialkyl peroxides, acyl hydroperoxides, and diacyl peroxides, as well as esters, such as tert-butyl perbenzoate and combinations of inorganic and organic initiators. Suitable initiators may be selected from 2,3-dimethyl-2,3-diphenylbutane, tert-butyl hydroperoxide, tert-amyl hydroperoxide, cumyl hydroperoxide, 1 ,1 ,3,3-tetramethylbutyl hydroperoxide, isopropylcumyl hydroperoxide, p-menthane hydroperoxide, 2,5-di(tert- butylperoxy)-2,5-dimethyl-3-hexyne, 3,6,9-triethyl-3,6,9-trimethyl-1 ,4,7-triperoxonane, di(tert- butyl)peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di(tert-butylperoxy-isopropyl) benzene, tert-butyl cumyl peroxide, di-(tert-amyl)-peroxide, dicumyl peroxide, butyl 4,4-di(tert- butylperoxy)valerate, tert-butylperoxybenzoate, 2,2-di(tert-butylperoxy)butane, tert-amyl peroxy-benzoate, tert-butylperoxy-acetate, tertbutylperoxy-(2-ethylhexyl)carbonate, tertbutylperoxy isopropyl carbonate, tert-butyl peroxy-3,5,5-trimethyl-hexanoate, 1 ,1 -di(tert- butylperoxy)cyclohexane, tert-amyl peroxyacetate, tert-amylperoxy-(2-ethylhexyl)carbonate, 1 , 1 -di(tertbutylperoxy)-3,5,5-trimethylcyclohexane, 1 , 1 -di(tert-amylperoxy)cyclohexane, tert- butyl-monoperoxy-maleate, 1 ,1 ’-azodi(hexahydrobenzonitrile), tert-butyl peroxy-isobutyrate, tert-butyl peroxydiethylacetate, tert-butyl peroxy-2-ethylhexanoate, dibenzoyl peroxide, tertamyl peroxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, 1 ,1 ,3,3-tetramethylbutylperoxy- 2-ethylhexanoate, ammonium peroxodisulfate, 2,5-dimethyl-2,5-di(2- ethylhexanoylperoxy)hexane, 2,2’-azodi(2-methylbutyronitrile), 2,2’-azodi(isobutyronitrile), didecanoyl peroxide, potassium persulfate, dilauroyl peroxide, di(3,5,5-trimethylhexanoyl) peroxide, tert-amyl peroxypivalate, tert-butyl peroxyneoheptanoate, 1 ,1 , 3, 3- tetramethylbutyl peroxypivalate, tert-butyl peroxypivalate, dicetyl peroxydicarbonate, dimyristyl peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, di(4-tert-butylcyclohexyl) peroxydicarbonate, diisopropyl peroxydicarbonate, tert-butyl peroxyneodecanoate, di-sec- butyl peroxydicarbonate, tert-amyl peroxyneodecanoate, cumyl peroxyneoheptanoate, di(3- methoxybutyl) peroxydicarbonate, 1 ,1 , 3, 3- tetramethylbutyl peroxyneodecanoate, cumyl peroxyneodecanoate, diisobutyryl peroxide, and mixtures thereof.

[0105] According to certain preferred embodiments, in the process for the preparation of the abovedescribed aqueous dispersion poly(meth)acrylates (composition P), the initiator may be used in a sufficient amount to initiate the polymerization reaction at a desired rate. In general, an amount of initiator of from 0.01% to 5% by weight, preferably of from 0.1% to 4% by weight, based on the total weight of monomers in the monomer composition, is sufficient. The amount of initiator is most preferably of from 0.01% to 2% by weight, based on the total weight of monomers in the monomer composition.

[0106] According to certain preferred embodiments, in the process for the preparation of the abovedescribed aqueous dispersion poly(meth)acrylates (composition P), surfactants or emulsifiers which are suitable for stabilizing the aqueous dispersion poly(meth)acrylates (composition P) may include those conventional surface-active agents for polymerization processes. The surfactant or surfactants can be added to the aqueous phase and / or the monomer phase. An effective amount of surfactant in a seed process is the amount which was chosen for supporting the stabilization of the particle as a colloid, the minimization of contact between the particles and the prevention of coagulation. In a non-seeded process, an effective amount of surfactant is the amount which was chosen for determining the particle size.

[0107] The type and the amount of the surfactant is governed typically by the number of particles, their size and their composition. Typically, the surfactant is used in amounts of from 0% to 20% by weight, preferably from 0% to 10% by weight, more preferably from 0% to 5% by weight, based on the total weight of the monomers in the monomer composition. The amount of surfactant includes all values and sub-values therebetween, based on the total weight of the monomer in the monomer composition. The polymerization may also be conducted without using surfactants.

[0108] According to certain preferred embodiments, in the process for the preparation of the abovedescribed aqueous dispersion poly(meth)acrylates (composition P), the chain transfer agent used therein may be selected from n-dodecyl mercaptan, carbon tetrachloride, carbon tetrabromide, bromotrichloro methane, 4-methyl benzenethiol, isooctyl 3- mercaptopropionate, tert-nonyl mercaptan, 4,4’-thiobis benzenethiol, tert dodecyl mercaptan, alphamethyl styrene dimer, thioglycolic acid, 2-ethylhexyl thioglycolate, butyl 3-mercaptopropionate, 1 ,8- dimercapto-3,6-dioxa octane and combinations thereof, preferably n-dodecyl mercaptan.

[0109] The monomer composition used for polymerization in the embodiments related to water-borne adhesive compositions of the present invention may comprise 0.10% to 0.20% by weight of the chain transfer agent, wherein the weight percentage is based on the total weight of monomers in the monomer composition. In preferred embodiments, the chain transfer agent is n-dodecyl mercaptan.

[0110] The aqueous dispersions described herein can be used to produce water-borne adhesive compositions which are substantially solvent-free. Preferably, the water-borne adhesive compositions comprise less than 0.5% by weight of solvents. More preferably, the water-borne adhesive compositions contain no solvents. In further preferred embodiments, the poly(meth)acrylates are produced preferably by copolymerization of the monomers in solvents, more preferably in solvents having a boiling range of 50 to 150°C, in particular from 60 to 120°C, using from 0.01% to 5% by weight, in particular from 0.1% to 2% by weight, based in each case on the total weight of the monomers, of polymerization initiators. Adhesive compositions comprising poly(meth)acrylates produced by copolymerization of the monomers in solvents are known herein as solvent-borne adhesive compositions.

[0111] In principle, all customary initiators are suitable. Examples of radical sources are peroxides, hydroperoxides and azo compounds, such as dibenzoyl peroxide, cumene hydroperoxide, cyclohexanone peroxide, di-t-butyl peroxide, cyclohexylsulfonyl acetyl peroxide, diisopropyl percarbonate, t-butyl peroctoate and benzopinacol. Preferred radical initiators are 2,2'- azobis(2-methylbutyronitrile) (Vazo® 67™ from DuPont), 2,2'-azobis(2-methylpropionitrile) (2,2'-azobisisobutyronitrile; AIBN; Vazo® 64™ from DuPont) and bis(4-tert-butylcyclohexanyl) peroxydicarbonate.

[0112] Preferred solvents for the production of the poly(meth)acrylates are alcohols such as methanol, ethanol, n- and iso-propanol, n- and iso-butanol, in particular isopropanol and / or isobutanol; hydrocarbons such as toluene and in particular benzines of a boiling range from 60 to 120°C; ketones, in particular acetone, methyl ethyl ketone, methyl isobutyl ketone; esters such as ethyl acetate, and mixtures of the solvents stated above. Particularly preferred solvents are mixtures containing isopropanol in amounts of 2% to 15% by weight, in particular from 3% to 10% by weight, based in each case on the solvent mixture used.

[0113] The poly(meth)acrylate or poly(meth)acrylates are crosslinked in accordance with preferred embodiments, in which at least one (meth)acrylic acid is present as a monomer, with specific compounds - so-called crosslinkers - by means of linking reactions - in particular in terms of addition or substitution reactions or else coordinative linking reactions - of the carboxylic acid functions present.

[0114] According to preferred embodiments, solvent-borne adhesive compositions of the present invention contain one or more crosslinkers.

[0115] The positions within the crosslinker molecules that react with the macromolecules are also referred to as "reactive centres". Crosslinker molecules contain two or more reactive centres and are therefore able to link two or more macromolecules to one another. Occasionally, there are also unwanted secondary reactions in which the reactive centres of the same crosslinker molecule react with only one macromolecule.

[0116] Fundamentally, two types of crosslinkers can be distinguished: 1 ) Covalent crosslinkers, whose reactive centres react with the macromolecules and thereby form a covalent bond between the reactive centre of the crosslinker and the attacked carboxylic acid group of the macromolecule. In principle, all types of reaction are considered for the formation of covalent bonds.

[0117] 2) Coordinative crosslinkers, whose reactive centres coordinatively attack the poly(meth)acrylate macromolecules and therefore form a coordinative bond between the reactive centre of the crosslinker and the attacked carboxylic acid group of the macromolecule. In principle, all types of reaction are considered for the formation of coordinative bonds.

[0118] In one embodiment, at least one poly(meth)acrylate is contained in adhesive compositions of the invention and is at least covalently crosslinked with one or more crosslinkers selected from the group consisting of glycidylamines, polyfunctional epoxides, polyfunctional aziridines and polyfunctional isocyanates. More preferably the poly(meth)acrylate here is crosslinked at least covalently with one or more crosslinkers selected from the group consisting of N,N,N',N'- tetrakis(2,3-epoxypropyl)cyclohexyl-1 ,3-dimethylamine, N,N,N’,N'-tetrakis(2,3-epoxypropyl)- m-xylyl-a,a'-diamine, (3,4-epoxycyclohexyl)methyl 3,4-epoxycyclohexylcarboxylate, trimethylolpropane tris(2-methyl-1 -aziridinepropionate), tolylene diisocyanate (TDI), tolylene 2,4-diisocyanate dimer, naphthylene 1 ,5-diisocyanates (NDI), o-tolylene diisocyanates (TODI), diphenylmethane diisocyanates (MDI), triphenylmethane triisocyanates, tris(p- isocyanatophenyl) thiophosphate and polymethylene-polyphenyl isocyanate.

[0119] The poly(meth)acrylates may be crosslinked with one or more covalent crosslinkers, one or more coordinative crosslinkers, or with a mixture of respectively one or more covalent and coordinative crosslinkers.

[0120] Preferably, for this, the adhesive composition contains covalent crosslinkers to a total of 0.015% to 0.1% by weight, more preferably to a total of 0.02% to 0.075% by weight, based in each case on the total weight of the poly(meth)acrylates.

[0121] In some preferred embodiments, the solvent-borne adhesive composition contains covalent crosslinkers to a total of 0.015% to 0.1% by weight, more preferably to a total of 0.02% to 0.075% by weight, based in each case on the total weight of the poly(meth)acrylates.

[0122] In further preferred embodiments, adhesive compositions of the present invention, especially water-borne adhesive compositions, are substantially free of crosslinkers. In further preferred embodiments, the water-borne adhesive composition of the present invention contains no crosslinkers. According to preferred embodiments, the adhesive composition comprises at least one tackifier resin, in particular and preferably in combination with at least one poly(meth)acrylate. Especially, both solvent-borne and water-borne adhesive compositions of the present invention may comprise at least one tackifier resin, in particular and preferably in combination with at least one poly(meth)acrylate.

[0123] All known tackifier resins, especially those compatible with poly(meth)acrylates, are considered in principle. Preferably, the adhesive composition comprises at least one tackifier resin selected from terpene phenol resins and rosin esters, wherein the adhesive composition more preferably comprises at least one rosin ester.

[0124] The rosin ester is in particular and preferably a pentaerythritol rosin ester. As has become apparent, this can further improve the flame retardant effect, which is particularly reflected in minimized combustion distances and further-reduced soot formation.

[0125] Preferably, the adhesive composition of the invention contains 18% to 32% by weight, more preferably 22% to 30% by weight, of tackifier resins, more preferably of rosin esters.

[0126] This achieves particularly good characteristics with regard to the object to be achieved. In particular, optimal adhesive properties are hereby achieved.

[0127] According to preferred embodiments of the invention, the adhesive composition comprises at least one poly(meth)acrylate and at least one tackifier resin, wherein the weight ratio of poly(meth)acrylates present to tackifier resins present is preferably from 60:40 to 95:5, preferably from 65:35 to 75:25, more particularly 70:30.

[0128] This achieves particularly good characteristics with regard to the object to be achieved.

[0129] According to other preferred embodiments, the adhesive composition contains no tackifier resin. In these embodiments, the tack required for the respective application is achieved by other components to a sufficient extent, as for example solely by the use of a polymer which itself already has sufficient properties, which are not attenuated to an undesirable extent by any further components.

[0130] According to preferred embodiments, the water-borne adhesive composition of the present invention can be free of any tackifier resins. The water-borne adhesive composition of the present invention is preferably substantially free of any tackifier resins. As used herein, the term “substantially free” means that a tackifier resin is present, if at all, as an incidental impurity, such as in an amount of less than 0.04% by weight based on the total mass of the water-borne adhesive composition. According to the present invention, the pressure sensitive adhesive composition of the present invention is preferably completely free of any tackifier resins. As used herein, the term “completely free” means that a tackifier resin is not present in the pressure sensitive adhesive composition at all.

[0131] This achieves particularly good characteristics with regard to the object to be achieved.

[0132] Furthermore, the pressure-sensitive adhesive composition of the invention may comprise further additives, for example

[0133] - plasticizers, e.g. low molecular weight poly(meth)acrylates, phthalates, water-soluble plasticizers;

[0134] - functional additives, e.g. initiators and accelerators;

[0135] - electrically conductive materials, e.g. conjugated polymers, doped conjugated polymers, metal pigments, metal particles, metal salts, metal-coated particles, e.g. silver-coated spheres; graphite, conductive carbon blacks, carbon fibres, ferromagnetic additives;

[0136] - foaming agents, expanding agents, expandable hollow spheres; the latter, however, only in an amount which does not adversely affect the flame retardancy effect;

[0137] - compounding agents, nucleating agents;

[0138] - ageing inhibitors, e.g. primary and secondary antioxidants; light stabilizers, ozone protectants;

[0139] - pulverulent and granular fillers, dyes and pigments, e.g. fibres, carbon blacks, zinc oxides, titanium dioxide, chalks, silicas, silicates, solid or hollow glass spheres, solid or hollow polymer spheres, solid or hollow ceramic spheres, microspheres of other materials;

[0140] - organic fillers;

[0141] - defoaming agents;

[0142] - dispersing agents.

[0143] According to preferred embodiments, the adhesive composition comprises at least one amine. More preferably, the pressure-sensitive adhesive composition comprises at least one sterically hindered N-alkoxyamine.

[0144] According to preferred embodiments, the solvent-borne adhesive composition of the present invention comprises at least one amine. More preferably, the pressure-sensitive solvent-borne adhesive composition comprises at least one sterically hindered N-alkoxyamine.

[0145] In particular, the adhesive composition comprises at least one sterically hindered N- alkoxyamine, e.g. a reaction product of N,N"-1 ,2-ethanediylbis(1 ,3-propanediamine) with cyclohexane and peroxidized N-butyl-2,2,6,6-tetramethyl-4-piperidineamine-2,4,6-trichloro- 1 ,3,5-triazine (CAS No. 191680-81 -6), which is available for example under the trade name FLAMESTAB® NOR® 116 from BASF SE.

[0146] According to preferred embodiments, the solvent-borne adhesive composition of the present invention comprises at least one sterically hindered N-alkoxyamine, e.g. a reaction product of N,N"-1 ,2-ethanediylbis(1 ,3-propanediamine) with cyclohexane and peroxidized N-butyl-

[0147] 2.2.6.6-tetramethyl-4-piperidineamine-2,4,6-trichloro-1 ,3,5-triazine (CAS No. 191680-81 -6), which is available for example under the trade name FLAMESTAB® NOR® 116 from BASF SE.

[0148] According to preferred embodiments, the adhesive composition comprises at least one substance selected from the group consisting of 4-piperidinol, 2,2,6,6-tetramethyl-1 - (undecyloxy)-, 4,4'-carbonate (CAS: 705257-84-7) and N-(1 , 1 -dimethylethyl)bis(2- benzothiazolesulfene)amide (CAS: 3741 -80-8).

[0149] According to preferred embodiments, the solvent-borne adhesive composition of the present invention comprises at least one substance selected from the group consisting of 4-piperidinol,

[0150] 2.2.6.6-tetramethyl-1 -(undecyloxy)-, 4,4'-carbonate (CAS: 705257-84-7) and N-(1 ,1 - dimethylethyl)bis(2-benzothiazolesulfene)amide (CAS: 3741 -80-8).

[0151] As has become apparent, the flame retardancy performance of the adhesive composition can be further optimized with such adjuvants.

[0152] Preferably, the amount of amines present, in particular of sterically hindered N-alkoxyamines such as the above-mentioned FLAMESTAB® NOR® 1 16, is from 0.2% to 2% by weight, more preferably 0.5% to 1.5% by weight, based in each case on the total mass of the adhesive composition.

[0153] According to preferred embodiments, for the solvent-borne adhesive composition of the present invention, the amount of amines present, in particular of sterically hindered N- alkoxyamines such as the above-mentioned FLAMESTAB® NOR® 116, is from 0.2% to 2% by weight, more preferably 0.5% to 1 .5% by weight, based in each case on the total mass of the solvent-borne adhesive composition.

[0154] According to further preferred embodiments, the water-borne adhesive composition of the present invention does not contain any amine. More preferably, the water-borne adhesive composition of the present invention does not contain any sterically hindered N-alkoxyamine. This embodiment similarly achieves good characteristics with regard to the object to be achieved, in particular optimal adhesive properties and flame retardancy properties even after storage under hot and humid conditions are hereby achieved. According to alternative embodiments, the water-borne adhesive composition of the present invention may contain at least one amine. More preferably, the water-borne adhesive composition of the present invention contains at least one sterically hindered N-alkoxyamine. Especially preferably, the water-borne adhesive composition of the present invention comprises at least one sterically hindered N-alkoxyamine, e.g. a reaction product of N,N"-1 ,2- ethanediylbis(1 ,3-propanediamine) with cyclohexane and peroxidized N-butyl-2,2,6,6- tetramethyl-4-piperidineamine-2,4,6-trichloro-1 ,3,5-triazine (CAS No. 191680-81 -6), which is available for example under the trade name FLAMESTAB® NOR® 1 16 from BASF SE.

[0155] This achieves good characteristics with regard to the object to be achieved, in particular optimal adhesive properties and flame retardancy properties even after storage under hot and humid conditions are hereby achieved.

[0156] The adhesive composition of the invention is preferably produced from dispersion or solution by sequential mixing-in of the components - including the flame retardant and substances present optionally such as the stated amines or amides -, subsequent shaping of the dispersion or solution to a web, and subsequent removal of the solvent used. The solvent here can be water or an organic solvent.

[0157] According to preferred embodiments, a composition comprising at least one flame retardant of formula I), preferably of formula II), more preferably of formula III) of the present invention is dispersed in an aqueous dispersion medium, for example water, resulting in an aqueous- dispersed composition comprising at least one flame retardant of formula I), preferably of formula II), more preferably of formula III) of the present invention (hereinafter known as composition F). As mentioned above, an aqueous-dispersed composition comprising the poly(meth)acrylates of the present invention obtained by emulsion polymerization described above is known as composition P. Optionally, a composition comprising at least one amine, for example the above-mentioned FLAMESTAB® NOR® 1 16, is dispersed in an aqueous dispersion medium, for example water, resulting in an aqueous-dispersed composition comprising at least one amine of the present invention (hereinafter known as composition A).

[0158] According to further preferred embodiments, the adhesive composition of the present invention is produced from dispersion in an aqueous dispersion medium, and subsequently by sequential mixing-in of the compositions F and P, and optionally composition A, resulting in a final aqueous-dispersed adhesive composition D. According to even more preferred embodiments of the present invention, the adhesive composition of the present invention is produced from dispersion in an aqueous dispersion medium, by sequential mixing-in of the aqueous-dispersed compositions F and P only, resulting in a final aqueous-dispersed adhesive composition D. The aqueous-dispersed adhesive composition D described herein corresponds to the waterborne adhesive composition of the present invention.

[0159] The water-borne adhesive composition of the present invention achieves good characteristics with regard to the object to be achieved, in particular optimal adhesive properties and flame retardancy properties even after storage under hot and humid conditions are hereby achieved.

[0160] A further subject of the present invention is any of the adhesive compositions described herein further comprising one or more rheology modifiers (thickeners), preferably synthetic rheology modifiers (thickeners), wherein the adhesive composition is preferably a water-borne adhesive composition.

[0161] The modes of action of rheology modifiers (thickeners) can essentially be divided into two types: (i) the thickening of the aqueous phase, i.e., non-associating, and (ii) association between rheology modifier molecules and particles. Representatives of the first type (i) compound group are water-soluble polyacrylic acids and polycoacrylic acids, which in the basic medium form polyelectrolytes of high hydrodynamic volume. The skilled person also refers to these for short as ASE (alkali swellable emulsion). They are distinguished by high resting shear viscosities and strong shear thinning. Another class of compounds are the modified polysaccharides, especially cellulose ethers such as carboxymethylcellulose, 2- hydroxyethylcellulose, carboxymethyl-2-hydroxyethylcellulose, methylcellulose, 2- hydroxyethylmethylcellulose, 2-hydroxyethylethylcellulose, 2-hydroxypropylcellulose, 2- hydroxypropylmethylcellulose, 2-hydroxybutylmethylcellulose. Additionally, included in this class of compound are less widely used polysaccharides such as starch derivatives and specific polyethers.

[0162] The action group of the type (ii) associative rheology modifiers are, in principle, block copolymers having a water-soluble middle block and hydrophobic end blocks, the end blocks interacting with the particles or with themselves and so forming a three-dimensional network with incorporation of the particles. Typical representatives are known to the skilled person as HASE (hydrophobically modified alkali swellable emulsion), HELIR (hydrophobically modified ethylene oxide urethane) or HMHEC (hydrophobically modified hydroxyethyl cellulose). In the case of the HASE rheology modifiers, the middle block is an ASE, and the end blocks are usually long, hydrophobic alkyl chains coupled on via polyethylene oxide bridges. In the case of the HELIR, the water-soluble middle block is a polyurethane, and in the HMHEC it is a 2- hydroxyethylcellulose. The non-ionic HELIR and HMHEC, in particular, are largely insensitive to pH.

[0163] The rheology modifiers (thickeners) may in some cases be stirred directly into dispersions containing the adhesive composition of the present invention, or in some cases are predispersed or prediluted advantageously in dispersion media, for example water, beforehand. The flame retardant of formula I), preferably of formula II), more preferably of formula III) of the present invention is largely incompatible with water, which acts as the dispersion medium. For example, in the case of the above-mentioned rheology modifiers (thickeners) of type (i), the rheology modifiers (thickeners) are known to increase the viscosity of the dispersion medium. By pre-thickening the dispersion medium with rheology modifiers or thickeners, such a step reduces the repulsion of incompatible particles of the flame retardant of the present invention as the particles are incorporated into the thickened network of the dispersion medium.

[0164] All customary rheology modifiers (thickeners) belonging to the above-mentioned types (i) and (ii) are suitable and can be used for obtaining the water-borne adhesive composition of the present invention.

[0165] According to preferred embodiments of the present invention, one or more rheology modifiers, preferably synthetic rheology modifiers, are added during the production steps of any one of the respective aqueous-dispersed compositions F, P, and D, and optionally A. Preferably, one or more rheology modifiers, preferably synthetic rheology modifiers, are added during the production steps of the respective aqueous-dispersed compositions F and D.

[0166] The expressions “rheology modifiers” or “thickeners” used herein are man-made polymers such as acrylic-based polymers, urethane-based polymers, modifications thereof, and the like. The expressions “rheology modifiers” or “thickeners” can be used interchangeably.

[0167] Examples of synthetic rheology modifiers include, but are not limited to, alkali swellable emulsions (ASE) (e.g., Sera Print M-PHC from Dystar and Rheovis AS 1187 from BASF, hydrophobically modified alkali swellable emulsions (HASE) (e.g., HV-80 from Byk Chemie), hydrophobically modified ethylene oxide urethanes (HELIR) (e.g., Borchigel 0434 and Borchigel 0625 from Borchers), hydrophobically modified polyethers (HMPE), hydrophobically modified hydroxyethyl celluloses (HMHEC) and hydrophobically ethoxylated aminoplast technology (HEAT). Particularly preferred are ASE and HELIR rheology modifiers.

[0168] Another subject of the present invention is the adhesive composition of the present invention which is obtained by a method comprising at least the following steps of: a) dispersing in a dispersion medium at least one flame retardant of formula I), preferably of II), more preferably of III) of the present invention, preferably by adding in the dispersion medium one or more rheology modifiers, preferably synthetic rheology modifiers, thereby obtaining an aqueous-dispersed composition F; and b) polymerizing a monomer composition of the poly(meth)acrylate in a dispersion medium, optionally adding in the dispersion medium one or more rheology modifiers, preferably synthetic rheology modifiers, thereby obtaining an aqueous-dispersed composition P; and c) optionally dispersing in a dispersion medium a composition comprising at least one amine of the present invention, optionally by adding in the dispersion medium one or more rheology modifiers, preferably synthetic rheology modifiers, thereby obtaining an aqueous-dispersed composition A; and d) mixing the compositions F and P and optionally composition A in a dispersion medium, preferably adding in the dispersion medium one or more rheology modifiers, preferably synthetic rheology modifiers, thereby obtaining an aqueous-dispersed adhesive composition D; and e) optionally coating on a carrier and subsequently drying the composition D, thereby obtaining the adhesive composition, wherein the dispersion medium is preferably water, and wherein the adhesive composition is preferably a water-borne adhesive composition.

[0169] According to further preferred embodiments, a method for obtaining the adhesive composition of the present invention, comprising at least the following steps: a) dispersing in a dispersion medium at least one flame retardant of formula I), preferably of II), more preferably of formula III) of the present invention, preferably by adding in the dispersion medium one or more rheology modifiers, preferably synthetic rheology modifiers, thereby obtaining an aqueous-dispersed composition F; and b) polymerizing a monomer composition of the poly(meth)acrylate in a dispersion medium, optionally adding in the dispersion medium one or more rheology modifiers, preferably synthetic rheology modifiers, thereby obtaining an aqueous-dispersed composition P; and c) optionally dispersing in a dispersion medium a composition comprising at least one amine of the present invention, optionally by adding in the dispersion medium one or more rheology modifiers, preferably synthetic rheology modifiers, thereby obtaining an aqueous-dispersed composition A; and d) mixing the compositions F and P and optionally composition A in a dispersion medium, preferably adding in the dispersion medium one or more rheology modifiers, preferably synthetic rheology modifiers, thereby obtaining an aqueous-dispersed composition A; and e) optionally coating on a carrier and subsequently drying the composition D, thereby obtaining the adhesive composition, wherein the dispersion medium is preferably water, and wherein the adhesive composition is preferably a water-borne adhesive composition. According to preferred embodiments of the present invention, no dispersing agents are used in any of the “dispersing” steps of the above-mentioned methods of the present invention. This achieves particularly good characteristics with regard to the object to be achieved.

[0170] According to certain embodiments of the present invention, one or more dispersing agents known to the skilled person may be used in any of the “dispersing” steps of the above- mentioned methods of the present invention.

[0171] According to further preferred embodiments of the present invention, the one or more rheology modifiers, preferably synthetic rheology modifiers, referred to in any of steps a), b), and c) are the same. According to further preferred embodiments of the present invention, the one or more rheology modifiers, preferably synthetic rheology modifiers, referred to in any of steps a), b), and c) are different. According to other preferred embodiments of the present invention, the one or more rheology modifiers, preferably synthetic rheology modifiers, referred to in any of steps a), b), and c) is a HEUR rheology modifier, for example Borchigel 0625. According to other preferred embodiments of the present invention, the one or more rheology modifiers, preferably synthetic rheology modifiers, referred to in any of steps a), b), and c) is an ASE rheology modifier, for example Sera Print M-PHC. According to other preferred embodiments of the present invention, the one or more rheology modifiers, preferably synthetic rheology modifiers, referred to in any of steps a), b), and c) are selected from the group consisting of HEUR rheology modifiers, ASE rheology modifiers, and a combination thereof.

[0172] Achieved herewith are very good flame retardancy qualities even after storage under hot and humid conditions, while at the same time the adhesive properties of the adhesive composition before and after storage under hot and humid conditions are not adversely affected.

[0173] According to preferred embodiments of the present invention, the one or more rheology modifiers, preferably synthetic rheology modifiers, are present in an amount of about 0.01 % to 2% by weight, preferably 0.05% to 1.5% by weight, more preferably 0.1% to 1% by weight, based in each case on the total mass of the aqueous-dispersed composition F, preferably based in each case on the total solids content of the aqueous-dispersed composition F.

[0174] According to preferred embodiments of the present invention, the one or more rheology modifiers, preferably synthetic rheology modifiers, are present in an amount of about 0.01 % to 2% by weight, preferably 0.05% to 1.5% by weight, more preferably 0.1% to 1% by weight, even more preferably 0.13% to 0.9% by weight, particularly preferably 0.15% to 0.8% by weight, based in each case on the total mass of the aqueous-dispersed adhesive composition D, preferably based in each case on the total solids content of the aqueous-dispersed adhesive composition D. This achieves particularly good characteristics with regard to the object to be achieved. In particular, optimal adhesive properties and flame retardancy qualities even after storage under hot and humid conditions are hereby achieved.

[0175] In order to further improve the flame-retardancy properties of the water-borne adhesive composition of the present invention, the person skilled in the art may suitably adapt the waterborne adhesive composition of the present invention by adding further ingredients as synergists to the water-borne adhesive composition. According to alternative preferred embodiments, the above-mentioned aqueous-dispersed composition A, for example an aqueous-dispersed composition comprising the above-mentioned FLAMESTAB® NOR® 1 16, may be added to the water-borne adhesive composition of the present invention (also known as adhesive composition D).

[0176] In certain embodiments where the aqueous-dispersed composition A is present in the waterborne adhesive composition or adhesive composition D of the present invention, only small amounts of the aqueous-dispersed composition A are needed, for example between 0.5 % to 2 % by weight, preferably 1 % by weight, based in each case on the total mass of the aqueous- dispersed composition D, preferably based in each case on the total solids content of the adhesive composition D. The quantity of the flame retardant having any of Formula I), II), or III) of the present invention, preferably Formula III), may be reduced accordingly. For instance, the amount of flame retardant having any of Formula I), II), or III) of the present invention, preferably Formula III) may be reduced to 5 % to 15% by weight, preferably 10 % by weight, based in each case on the total mass of the adhesive composition D, preferably based in each case on the total solids content of the adhesive composition D. In further embodiments where the aqueous-dispersed composition A is present in the water-borne adhesive composition of the present invention, very small amounts of one or more rheology modifiers, preferably synthetic rheology modifiers, may be present in the final aqueous-dispersed adhesive composition D, for example 0.01 % to 0.1 % by weight, preferably 0.01 % to 0.05% by weight, more preferably 0.01% to 0.03% by weight, based in each case on the total mass of the adhesive composition D, preferably based in each case on the total solids content of the adhesive composition D.

[0177] Optionally, the person skilled in the art may suitably add one or more dispersing agents, one or more protonating agents and one or more defoaming agents known to the skilled person, in order to adjust or improve the rheological properties of the aqueous-dispersed composition A.

[0178] Without being wished to bound by theory, it is believed that even with reduced amounts of the flame retardant of the present invention, for example the flame retardant of formula I), preferably of formula II), more preferably of formula III), together with the presence of a very small amount of the aqueous-dispersed composition A, such a water-borne adhesive composition may achieve very good adhesive properties and flame retardancy qualities even after storage under hot and humid conditions.

[0179] The production of the adhesive composition of the invention comprising the flame retardant and substances present optionally such as the stated amines or amides - and the subsequent coating to form a layer of adhesive can also take place solventlessly. This may be, for example, in the extrusion process by sequential mixing-in of the components into the melted poly(meth)acrylate or by sequential mixing-in of the components into a monomer-polymer mixture without additional solvent, called UV syrup, combined with subsequent coating and light-induced, in particular almost quantitative, polymerization in the web.

[0180] Another subject of the present invention is an adhesive tape comprising at least the adhesive composition of the invention.

[0181] The adhesive tape of the invention also has very good flame retardancy qualities and adhesivemechanical properties even after storage under hot and humid conditions, owing to the presence of the adhesive composition of the invention.

[0182] The adhesive tape of the invention may in principle have any construction.

[0183] For the purposes of this invention, the general expression "adhesive tape" encompasses all sheetlike structures whose extent in two spatial directions (x-direction and y-direction; length and width) is substantially greater than in the third spatial direction (z-direction; thickness) such as films or film portions, tapes with extended length and limited width, tape portions, diecuts, labels and the like.

[0184] According to preferred embodiments, the tape is an adhesive transfer tape which consists of the adhesive composition of the invention.

[0185] In order to be able to apply the adhesive tape, for example rolled up to form a pancake roll or cross-wound to form a spool, without the tape sticking to itself, the layer of adhesive is preferably covered with at least one release liner.

[0186] According to further preferred embodiments, the adhesive tape comprises at least one layer of the adhesive composition of the invention and at least one further layer, such as in particular a carrier and / or at least one further layer of adhesive.

[0187] In such embodiments as well, at least one side of the adhesive composition of the adhesive tape is preferably covered with a release liner in order to enable trouble-free winding and unwinding and to protect the adhesive composition(s) from soiling. Release liners typically consist of a one- or two-sidedly siliconized polymeric film (e.g. PET or PP) or a siliconized paper carrier. They are not considered part of the adhesive tape, but are only temporarily connected to it as an aid.

[0188] In the embodiments of the adhesive tape comprising at least one layer of the adhesive composition of the invention and at least one further layer, such as a carrier, both the full-area coating of the adhesive composition of the invention on the further layer, such as the carrier, and any part-area coating, such as a strip-shaped coating, are encompassed by the invention.

[0189] Another subject of the invention is the use of the adhesive composition of the invention as a flame-retardant adhesive, more particularly as a flame-retardant adhesive in the outfitting of aircraft, trains, ships, vehicles and buildings.

[0190] The adhesive composition here can be used as a layer as part of an adhesive tape or directly as a hotmelt adhesive.

[0191] According to preferred embodiments, the solvent-borne adhesive composition of the present invention can be used as a layer as part of an adhesive tape or directly as a hotmelt adhesive.

[0192] The adhesive composition of the invention is used in one embodiment for producing permanent bonds in interior spaces, more preferably for fixing thermal insulation material, in particular between interior and exterior walls; for fixing non-textile floors in wet rooms, e.g. in kitchens and toilets; for fixing floor coverings in general; as an adhesive for moisture barrier applications and / or in corrosion protection applications and / or for fixing mirrors and / or lights.

[0193] In another embodiment, the adhesive composition of the present invention is used for bonding components in electronic devices, automobiles, medical devices, robotics and heavy machinery.

[0194] In a further embodiment, the adhesive composition of the invention is used for producing bonds, preferably permanent bonds, in electric vehicles. The adhesive composition here is more preferably used for the production of bonds in the battery, in particular for the production of assembly bonds (mounting), for example for bonding refractory materials between battery cells; for bonding flexible printed circuit boards; for bonding foams, in particular silicone foams; for the production of bonds for the purpose of electrical isolation of battery modules and / or battery components, in particular the electrical isolation of battery cells (battery cell wrapping) and / or of the heating / cooling plate.

[0195] Another subject of the invention is the use of the adhesive tape of the invention as flameretardant adhesive tape in the outfitting of aircraft, trains, ships, vehicles and buildings, and for the production of bonds as defined above for the adhesive composition of the invention. The adhesive composition of the present invention is preferably used in one embodiment for producing permanent bonds in any other applications. The use of the adhesive composition of the present invention is not limited to only the abovementioned applications. Rather, it could be utilized in any other applications where permanent bonds are required. It could further be utilized in any other applications where permanent bonds along with flame retardancy are required.

[0196] A number of examples are described below to further illustrate the invention. The examples according to the invention are marked with an "E", while the comparative examples are marked with a "V".

[0197] The compositions of the adhesives are summarized in Table 1 a and the results of the tests in Table 1 b.

[0198] The information in Table 1 a represents weight fractions based on the total mass of the adhesive composition, i.e. a weight percentage relative to 100% of the adhesive composition. This applies to the inventive examples E1 to E5 and comparative examples V1 to V4.

[0199] For inventive example E6, the information in Table 1 a represents weight fractions based on the total solids content of the water-borne adhesive composition, i.e. a weight percentage relative to 100% of the solids content of the water-borne adhesive composition.

[0200] Hence the amounts of the components in each example make 100% by weight in each case. The amount of the crosslinker Erisys GA 240 is so small in its magnitude that the correspondingly smaller amount of the acrylate is not reproduced, for the sake of visual clarity, but has been rounded up accordingly.

[0201] Raw materials used:

[0202] 2-Ethylhexyl acrylate (2-EHA): CAS Number: 103-11 -7

[0203] Methyl acrylate (MA): CAS Number: 96-33-3

[0204] Acrylic acid (AA): CAS Number: 79-10-7 n-Butyl acrylate (BA): CAS Number 141 -32-2

[0205] Methyl methacrylate (MM A): CAS Number: 80-62-6

[0206] 2-Hydroxyethyl methacrylate (HEMA): CAS Number: 868-77-9 Polyacrylate (P1): Polymer of 2-ethylhexyl acrylate, methyl acrylate and acrylic acid, prepared as described below

[0207] Polyacrylate (P2): Aqueous pre-dispersion of polymer of n-butyl acrylate, acrylic acid, methyl methacrylate and 2-hydroxyethyl methacrylate, prepared as described below

[0208] Vazo 67: 2,2'-Azodi(2-methylbutyronitrile), CAS Number 13472- 08-7, Akzo Nobel

[0209] Perkadox 16: Bis(4-tert-butylcyclohexanyl) peroxydicarbonate, CAS Number 15520-11-3, Akzo Nobel

[0210] Foral 105 E: Hydrogenated pentaerythritol rosin ester, softening point approx. 100°C; MW ~ 1002 g / mol; Eastman

[0211] Erisys GA 240: N,N,N',N'-Tetrakis(2,3-epoxypropyl)-m-xylene-a,a'- diamine, Emerald Performance Materials

[0212] GC-BDP: Bisphenol A bis(diphenyl phosphate), CAS Number: 5945-33-5; GREENCHEMICALS SPA

[0213] Formula III): Flame retardant of formula III):

[0214] 3,9-Dibenzyl-2,4,8,10-tetraoxa-3,9- diphosphaspiro[5.5]undecane 3,9-dioxide

[0215] CAS Number: 20544-37-0

[0216] Ulterion N2000: Flame retardant: cyclic phosphonate without aromatic residue; CAS: 170836-68-7

[0217] Flamestab NOR 116 FF: CAS Number: 191680-81 -6; BASF SE

[0218] Borchigel 0625: HELIR associative rheology modifier (thickener);

[0219] Borchers Production of the polyacrylate P1

[0220] A conventional 2 L glass reactor suitable for radical polymerizations with evaporative cooling was charged with 300 g of a monomer mixture of 219 g of 2-ethylhexyl acrylate, 60 g of methyl acrylate and 21 g of acrylic acid and also 200 g of acetone: special boiling point spirit 60 / 95 (1 :1 ). After 45 minutes of passage of nitrogen gas with stirring, the reactor was heated up to 58°C and 0.15 g of 2,2'-azodi(2-methylbutyronitrile) (CAS: 13472-08-7), dissolved in 6 g acetone, was added. Subsequently, the external heating bath was heated to 75°C and the reaction was conducted constantly at this external temperature. After 1 h reaction time, a further 0.15 g of 2,2'-azodi(2-methylbutyronitrile), dissolved in 6 g of acetone, was added. After 3 hours, dilution took place with 90 g of special boiling point spirit 60 / 95.

[0221] After 5 h 30 min reaction time, 0.45 g of bis(4-tert-butylcyclohexanyl) peroxydicarbonate, dissolved in 9 g of acetone, was added. After 7 hours reaction time, a further 0.45 g of bis(4- tert-butylcyclohexanyl) peroxydicarbonate (CAS: 15520-11 -3), dissolved in 9 g acetone, was added. After 10 hours reaction time, dilution took place with 90 g of special boiling point spirit 60 / 95. The reaction was terminated after 24 h reaction time and cooling took place to room temperature.

[0222] The resulting polyacrylate has a glass transition temperature (Tg) according to Test Method A of about -34°C.

[0223] The resulting polyacrylate P1 was used in the production of solvent-borne adhesive composition of the present invention.

[0224] Production of the polyacrylate P2

[0225] The pressure sensitive adhesive dispersion polymers were prepared by a free radical emulsion polymerization process combining an initial reactor charge and two reactant feeds. A double-wall 6-liter glass reactor connected to a cryostat enabling temperature control and equipped with a blade stirrer was charged with 800 g of deionized water and 40 g of a polymethyl methacrylate seed dispersion with 20% by weight solid content and an average particle size of 30 nm.

[0226] A monomer pre-emulsion was prepared consisting of 2.76 kg reactants (approximately 87.41% of BA, 9.5% of MMA, 1% of AA, 2% of HEMA, and 0.09% of n-dodecyl mercaptan by weight, based in each case on the total amount of monomers in the monomer composition), 22.8 g of anionic surfactant (C13-C15 alkyl aryl sulfonate) and 1 .2 kg deionized water and treated a with dissolver disk over 5 min, obtaining a homogenous monomer emulsion. Furthermore, an initiator solution was prepared by dissolving 8 g of sodium persulfate in 72 g deionized water. After the initial charge had been heated to 85 °C under agitation the monomer pre-emulsion and the initiator solution were continuously fed into the reactor over four hours. The reaction temperature was maintained constantly at 85 °C. The monomer inlet was finally flushed with 50 g of water. The batch was agitated further for another 30 min before cooling down to 60 °C. For the post-activation a 5% by weight of solution of 2.5 g erythorbic acid was fed to the batch over one hour and a first shot of a 10% by weight of solution of 1.1 g tert-butyl hydroperoxide was added with starting the erythorbic acid feed start and a second shot after 30 minutes.

[0227] The batch was then let cool down to ambient temperature (20-25 °C), neutralized with 10% by weight of sodium hydroxide solution to pH 7.5, sieved through a 100 pm filter cloth.

[0228] The resulting polyacrylate P2 was used in the production of water-borne adhesive composition of the present invention.

[0229] Production of the adhesive compositions, in this case pressure-sensitive adhesive compositions, of the comparative examples V1 to V4 and of the examples E1 to E5 according to the invention

[0230] In the solution of the polyacrylate, the tackifier resin Foral 105 E was dissolved in a weight ratio of 70:30, based on the solids content of polymer.

[0231] Added to this solution, in examples V2 to V4 and E1 to E5, was the respective flame retardant bisphenol A diphenyl phosphate (BDP), Ulterion N2000 or the compound of formula III), at the weight percentage specified in Table 1 a.

[0232] In addition, 1% by weight of Flamestab NOR 1 16 FF was added in each of these examples.

[0233] Subsequently, additional acetone was used for dilution so that a solids content of 38% was attained before coating.

[0234] In example V1 , no flame retardant and no Flamestab NOR 1 16 FF were added.

[0235] The respective mixture was homogenized by means of devices known to the skilled person, such as a roller bench (around 12 h) or a dissolver, depending on the compatibility of the individual components. Then a crosslinker solution (3% by weight of Erysis GA 240 in acetone) with a metering of 0.075 parts by weight, based on 100 parts by weight of the polyacrylate, was added and the adhesive composition was coated on a siliconized film using a coating bar on a laboratory coating table. The coatings were then dried at 120°C for 15 min, attaining a coating weight of 50 g / m2.

[0236] Exemplary adhesive compositions E1 to E5 and comparative examples V1 to V4 produced herein correspond to the solvent-borne adhesive compositions of the present invention.

[0237] Double-sided adhesive tapes were produced for the tests. For this purpose, the layer of 50 g / m2adhesive was laminated on both sides onto a 23 pm thick etched PET film. In particular, solvent-borne adhesive compositions of the present invention were used for the production of the double-sided adhesive tapes.

[0238] Production of the water-borne acrylic adhesive composition D, in this case pressure-sensitive water-borne adhesive composition of the example E6 according to the invention

[0239] In example E6, the flame retardant of formula III) of the present invention was added to water, which acts as a dispersion medium, at the weight percentage as specified in Table 1 a. In addition, 1% by weight of a HEUR associative rheology modifier (Borchigel 0625, Borchers), based on the total solids content of the composition F (formula III) - equivalent to 0.63% by weight based on the total solids content of the adhesive composition D), was added. The mixture was stirred to disperse the flame retardant of formula III) in water, thereby obtaining the above-mentioned aqueous-dispersed composition F.

[0240] Subsequently, the composition F was added to and mixed with the polyacrylate pre-dispersion (P2; also known herein as composition P) in the amount as given in Table 1 a, thereby obtaining a final aqueous-dispersed adhesive composition D. The adhesive composition D was adjusted by stirred incorporation of 0.1% by weight of Borchigel 0625, based on the total solids content of the adhesive composition D. The mixture was stirred until no solid particles visible to the eye could be observed. No Flamestab NOR 116 FF was added.

[0241] The adhesive composition D was then coated on a PET (polyethylene terephthalate) film with a thickness of 23 pm using a coating bar on a laboratory coating table. The coatings were then dried at 105°C for about 5 min, attaining a coating weight of approximately 35 g / m2. The open side of the resultant single-sided adhesive tape was subsequently equipped with a siliconized liner.

[0242] Exemplary adhesive composition E6 produced herein corresponds to the water-borne adhesive composition of the present invention.

[0243] Test Methods

[0244] Unless stated otherwise, all measurements are conducted at 23°C and 50% relative air humidity. Unless otherwise indicated, all measurements were made with three specimens each and then the respective mean value was formed, as reported in Table 1 b.

[0245] Peel adhesion The determination of the peel adhesion is carried out as follows. A polished steel plate (ASTM D3330; cleaned three times with acetone using a cellulose cloth and evaporated for 10 min) with a thickness of 2 mm is used as a defined adhesion base. The bondable sheetlike element to be examined (50 g / m2PSA layer on 23 pm etched PET film) is cut to a width of 20 mm and a length of about 25 cm, unless otherwise specified, provided with a handling section and immediately afterwards pressed onto the adhesion base back and forth five times with a steel roller of 4 kg at a rate of advance of 10 m / min. Immediately thereafter, the bondable sheetlike element is peeled from the adhesion base at an angle of 180° with a tensile tester (from Zwick) at a velocity v = 300 mm / min, and the force required for this purpose at room temperature is measured. The measured value (in N / cm) is obtained as the average value from three individual measurements.

[0246] Peel adhesion 85 / 85

[0247] The peel adhesion is determined as described above with the difference that the samples were stored in an oven at 85°C and a relative humidity of 85% for 500 hours after preparation. After removal from the oven, the samples were dried at room temperature (23°C) for 72 h and then measured.

[0248] IR spectrum:

[0249] Adhesive tapes were analysed via IR before and after storage in a humid heating cabinet (500 h at 85°C / 85% relative humidity) at 70°C and subsequent drying - for 24 h to remove water.

[0250] Fourier Transform Infrared spectra (FTIR) were acquired on a Broker Vertex 70 with a platinum diamond Attenuated Total Reflectance (ATR) unit in the spectral range from 4000 to 400 cm'1at a resolution of 1 cm-1. The OPUS software was used for evaluation.

[0251] The penetration with light was carried out with a maximum depth of 5 pm, so that only the adhesive composition was analysed.

[0252] After baseline correction, the spectra were compared with each other, i.e. untreated = prior to storage compared to storage under the specified hot and humid conditions.

[0253] Congruent or near-congruent spectra are indicated as stable in the table with "Yes". Incongruent spectra are those with altered band intensities and band ratios and, possibly, newly created or disappeared bands are given the indication "No" accordingly.

[0254] Burning length and afterburn time The burning length and afterburn time before and after storage for 500 hours in an oven at 85°C and a relative humidity of 85% (85 / 85) are determined according to the "12s Vertical Bunsen Burner Test".

[0255] The 12s vertical Bunsen burner test is carried out according to FAR 25.853 (Appendix F Part I (a)(1 )(H)): The sample is held in a U-frame in a vertical free-hanging position, i.e. without being bonded to a substrate, and a Bunsen burner flame is applied from below for 12 s. After the flaming time of 12 s has expired, the burner is removed and the material is observed. The following parameters are documented: a) Average afterburn time (Afterburn time): Time in s during which the sample burns after the burner flame has been removed; b) Average burning length (Burning length): Distance from the initial sample edge to the furthest point at which the sample is damaged by burning.

[0256] At least 3 test specimens were tested.

[0257] The specimens are considered flame retardant if the following requirements have been met in accordance with FAR 25.853 (Appendix F Part I (a)(1 )(H)):

[0258] Average afterburn time (Burning time): < 15 s

[0259] Average burning length: < 203.2 mm.

[0260] Microshear travel (MST)

[0261] 10 mm x 50 mm pieces were cut from the adhesive tape and the resulting adhesive tape specimen was bonded to a polished, temperature-controllable 13 mm wide steel test plate, cleaned with acetone, in such a way that the longitudinal direction of the adhesive tape specimen was aligned in the transverse direction of the steel plate, the bond area had the dimensions I x w = 13 mm x 10 mm, and the adhesive tape overhung the steel plate on one side by a piece of length z = 2 mm. For fixing, the adhesive tape was then rolled down six times with a 2 kg steel roller at a speed of 10 m / min. On the side of the adhesive tape facing away from the steel plate, the adhesive tape was reinforced, flush with the edge overhanging the steel plate protruding by the piece of length z, with a stable adhesive strip (dimensions 4 mm x 25 mm; carrier 190 pm thick PET film), which served as a support for a travel sensor (not shown).

[0262] The arrangement prepared in this way was suspended vertically in such a way that the piece of length z of the adhesive tape specimen, overhanging the steel plate, pointed upwards. The steel test plate with the bonded sample was heated to 40°C and the adhesive tape specimen to be measured was loaded at the lower end via a clip at time to = 0 with a weight of 300 g.

[0263] The deformation of the sample under shear was measured by the travel sensor over a period of 15 minutes (starting at to) at a temperature of 40°C and a relative humidity of 50 ± 5%.

[0264] The shear distance after 15 min (maximum value; distance travelled by the upper edge of the sample downwards during the measurement) is reported as the result in pm. The shear travel measured in this way is a quantitative measure of the crosslinking status of the measured sample.

[0265] Furthermore, the MST elasticity is used to indicate in percentage terms how far the adhesive tape has moved back again within a period of 15 min after removal of the weight. The MST elasticity corresponds to the ratio

[0266] (MST after 15 min load)-(MST after 15 min unload)

[0267] (MST after 15 min load)

[0268] The smaller the remaining shear travel after removal of the weight, the higher the elasticity.

[0269] Glass transition temperature (Tg)

[0270] The static glass transition temperature is determined by way of differential scanning calorimetry according to DIN 53765. For this, approximately 5 mg of the sample are weighed out precisely into an aluminium crucible and then introduced into the measuring device (instrument: DSC 204 F1 , from Netzsch). An empty crucible is utilized as a reference. Two heating curves with a heating rate of 10 K / min are then recorded. The information on the glass transition temperature Tg refers to the glass transformation temperature value Tg according to DIN 53765:1994-03 of the second heating curve, unless otherwise specified in an individual case.

[0271] ble 1a

[0272] ble 1b

[0273] *: Sample completely burned up in less than 12 seconds: Flame retardancy test failed

[0274] **: Cohesive failure of the samples

[0275] ***: Tape completely burned up (> 203 mm)

[0276] 0: Flame extinguishes within the 12-second flaming duration

[0277] As is evident from the results in Table 1 b, only the examples E1 to E5 according to the invention pass the vertical Bunsen burner test and thus the flame retardancy test. At the same time, from the IR spectra of V2 and also V3 and V4 it is evident that with state-of-the-art flame retardants, a change in the adhesive composition is apparently achieved after storage under hot and humid conditions that does not occur in the examples E1 to E5 according to the invention, in which the adhesive composition comprises the molecule of formula III).

[0278] The fact that these effects are due to the selection of the flame retardant is evident from the comparative example V1 , in which the adhesive composition contains no flame retardants at all. Here, the IR spectra before and after storage under hot and humid conditions are virtually congruent.

[0279] The examples according to the invention also show a good adhesive force (measured by peel adhesion) before and after storage under hot and humid conditions. Examples E1 to E4, like V1 and V2, show an improved peel adhesion after storage under hot and humid conditions compared to prior to storage.

[0280] By contrast, a state-of-the-art cyclic phosphonate without at least one aromatic residue (V3, V4) results in performance losses compared to the comparative example without flame retardants (V1 ).

[0281] With the additional flame retardant bisphenol A bis(diphenyl phosphate) from the state of the art (V2), good adhesive properties can indeed be achieved even after storage under hot and humid conditions. However, V2 does not pass the flame retardancy test after storage under hot and humid conditions. Sample V1 , without flame retardants, does not pass the flame retardancy test even before storage.

[0282] On the basis of the microshear travel, it is evident that a comparatively high proportion, namely 25% by weight, of the flame retardant can be used in the adhesive compositions of the invention. This is not possible with a cyclic phosphonate without an aromatic residue from the state of the art, as is evident from example V4, because the samples failed cohesively.

[0283] With the examples according to the invention, it was thus possible to provide flame-retarded adhesive compositions which are still flame-retardant even after storage under hot and humid conditions. At the same time, the adhesive compositions of the invention have good adhesion properties before and after storage under hot and humid conditions.

Claims

Claims1 . Adhesive composition comprising at least one flame retardant of formula I):wherein A is selected from residues containing at least one substituted or unsubstituted aromatic group; and wherein R1and R2independently of one another are identical or different and are selected from hydrogen atoms and hydrocarbon-containing residues which may carry heteroatoms.

2. Adhesive composition according to Claim 1 , characterized in that R1and R2are bridged to one another to form a common hydrocarbon-containing heterocycle.

3. Adhesive composition according to Claim 1 or 2, characterized in that the at least one flame retardant contains a structure of formula II):wherein A and Ai independently of one another are identical or different and are selected from residues containing at least one substituted or unsubstituted aromatic group.

4. Adhesive composition according to any of the preceding claims, characterized in that the residues A or A and Ai are selected from phenyl and benzyl groups, wherein A or A and Ai more preferably are benzyl groups.

5. Adhesive composition according to any of the preceding claims, characterized in that the flame retardant comprises at least the compound of formula III):

6. Adhesive composition according to any of the preceding claims, characterized in that the adhesive composition contains 0.5% to 40% by weight, based on the total mass of the adhesive composition, of at least one flame retardant of formula I), preferably of formula II), more preferably of formula III).

7. Adhesive composition according to any of the preceding claims, characterized in that the adhesive composition is a pressure-sensitive adhesive composition.

8. Adhesive composition according to any of the preceding claims, characterized in that the adhesive composition comprises at least one poly(meth)acrylate, wherein the total amount of poly(meth)acrylates is preferably 40% to 99.5% by weight, based on the total mass of the adhesive composition.

9. Adhesive composition according to any of the preceding claims, characterized in that the adhesive composition comprises one or more rheology modifiers, preferably synthetic rheology modifiers, and wherein the total amount of the one or more rheology modifiers is preferably 0.01% to 2% by weight, based on the total mass of the adhesive composition, preferably based on the total solids content of the adhesive composition.

10. Adhesive composition according to any of the preceding claims, characterized in that the adhesive composition is obtained by a method comprising at least the following steps: a) dispersing in a dispersion medium at least one flame retardant of formula I), preferably of II), more preferably of III), preferably by adding in the dispersion medium one or more rheology modifiers, preferably synthetic rheology modifiers, thereby obtaining an aqueous-dispersed composition F; and b) polymerizing a monomer composition of the poly(meth)acrylate in a dispersion medium, optionally adding in the dispersion medium one or more rheology modifiers, preferably synthetic rheology modifiers, thereby obtaining an aqueous-dispersed composition P; and c) optionally dispersing in a dispersion medium a composition comprising at least one amine, optionally by adding in the dispersion medium one or more rheology modifiers,preferably synthetic rheology modifiers, thereby obtaining an aqueous-dispersed composition A; and d) mixing the compositions F and P and optionally composition A in a dispersion medium, preferably adding in the dispersion medium one or more rheology modifiers, preferably synthetic rheology modifiers, thereby obtaining an aqueous-dispersed adhesive composition D; and e) optionally coating on a carrier and subsequently drying the composition D, thereby obtaining the adhesive composition, wherein the dispersion medium is preferably water.11 . Adhesive composition according to any of the preceding claims, characterized in that adhesive composition comprises at least one tackifier resin, wherein the tackifier resin is preferably selected from terpene phenol resins and rosin esters, wherein the adhesive composition more preferably comprises at least one rosin ester.

12. Adhesive composition according to any of the preceding claims, characterized in that the adhesive composition comprises at least one amine, preferably at least one sterically hindered N-alkoxyamine.

13. Adhesive tape comprising at least one adhesive composition according to any of Claims 1 to 12.

14. Adhesive tape according to Claim 13, characterized in that the adhesive tape is an adhesive transfer tape which consists of the adhesive composition according to any of Claims 1 to 12, or in that the adhesive tape comprises at least one layer of the adhesive composition according to any of Claims 1 to 12 and at least one further layer.

15. Use of the adhesive composition according to any of Claims 1 to 12 as a flameretardant adhesive, more particularly as a flame-retardant adhesive in the outfitting of aircraft, trains, ships, vehicles and buildings.

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