Resin soap-modified pressure-sensitive adhesive

Abstract

Adhesive compound, including: a) one or more poly(meth)acrylates totaling 35 to 65 wt.%, and b) one or more synthetic rubbers comprising a total of 15 to 45 wt.%, each based on the total weight of the pressure-sensitive adhesive, characterized in that the pressure-sensitive adhesive comprises at least one resin soap.

Description

[0001] The invention relates to the technical field of pressure-sensitive adhesives, such as those widely used in adhesive tapes for the temporary or permanent bonding of two materials. More specifically, the invention proposes a pressure-sensitive adhesive based on a mixture of poly(meth)acrylate and synthetic rubber, wherein the compatibility of these two chemically very different polymers is improved by the addition of a special additive.

[0002] The properties of an adhesive pressure-sensitive adhesive are strongly influenced by the framework or base polymers it contains. For example, polyacrylate-based adhesives are generally characterized by high UV and aging stability; natural or synthetic rubber-based adhesives exhibit particularly high cold flexibility. However, the negative properties of the framework polymer also affect the behavior of the adhesive. Natural or synthetic rubber-based adhesives, for instance, generally show only low aging stability. A logical approach to mitigating these unfavorable properties is to combine two or more framework polymers.

[0003] A frequent problem arises from the fact that the chemically different framework polymers are usually incompatible with each other, meaning they mix poorly. This leads to the polymers forming separate phases. This typically occurs when domains of one framework polymer are present as a dispersed phase within a continuous phase of the other framework polymer. The lower the compatibility of the framework polymers, the larger the resulting domains.

[0004] For example, mixtures of the polyacrylates and synthetic rubbers described above, which differ greatly in their polarity, have proven to be very incompatible with each other.

[0005] It is obvious that the desired reduction of unfavorable properties and the simultaneous development of favorable properties of the combined framework polymers will only occur to an insufficient degree if the polymers are not sufficiently compatible with each other.

[0006] One well-known solution to this problem is to improve the compatibility of two or more framework polymers by adding compatibilizers.

[0007] Compatibilizers are substances that improve the compatibility, and thus the miscibility, of different framework polymers.

[0008] For example, WO 01 / 59024 A1 describes an adhesive composition comprising a polyacrylate, a synthetic rubber, and a compatibilizer, the latter being present in a proportion of up to 10 parts by weight, based on 100 parts by weight of the polymers. The compatibilizer either has a segment compatible with each of the polymers and is contained in one of the two phases; or it has an acrylate-reactive segment and a synthetic rubber-compatible segment and is contained, at least in part, in the synthetic rubber phase.

[0009] DE 697 25 511 T2 describes an adhesive composition comprising a tackifier and an aqueous emulsion latex system, which includes: (a) a polymer of at least one unsaturated ethylene monomer selected from the group consisting of acrylic acid, methacrylic acid, butyl acrylate, methyl methacrylate, 2-ethylhexyl acrylate, acrylic esters, styrene, vinyl esters, vinyl ethers, vinyl and vinylidene halides, N-vinylpyrrolidone, ethylene, C3 or higher α-olefins, allylamines, allylic esters of saturated monocarboxylic acids and their amides, propylene, 1-butene, 1-pentene, 1-hexene, 1-decene, allylamines, allyl acetate, allyl propionate, allyl lactate, their amides, mixtures thereof, 1,3-butadiene, 1,3-pentadiene, 1,4-pentadiene, cyclopentadiene, hexadiene isomers; and (b) an amount of a water-soluble protective colloid with a molecular weight of less than 75,000, selected from the group consisting of carboxymethylcellulose and its derivatives with a lower limit of carboxyl substitution of 0.7, hydroxyethylcellulose, ethylhydroxyethylcellulose, methylcellulose, methylhydroxypropylcellulose, hydroxypropylcellulose, poly(acrylic acid) and its alkali metal salts, ethoxylated starch derivatives, polyacrylates of sodium and other alkali metals, water-soluble starch glue, gelatin, water-soluble alginates, casein, agar, natural and synthetic gums, partially and fully hydrolyzed poly(vinyl alcohol), polyacrylamide, poly(vinylpyrrolidone), poly(methylvinylethermaleic anhydride), guar and its derivatives, gelatin and casein, sufficient to stabilize the latex system.

[0010] There is a continuing need for highly compatible pressure-sensitive adhesive formulations based on two or more framework polymers to meet the ever-expanding demands placed on pressure-sensitive adhesives.

[0011] The object of the invention was to provide an adhesive compound based on a poly(meth)acrylate and a synthetic rubber in which the two framework polymers have improved compatibility with each other and in which adhesively favorable properties of both framework polymer classes come into play, so that the adhesive compound meets a broad range of requirements.

[0012] A first and general object of the invention, with which this problem is solved, is an adhesive compound which a) one or more poly(meth)acrylates totaling 35 to 65 wt.%, and b) one or more synthetic rubbers totaling 15 to 45 wt.%, Each is based on the total weight of the pressure-sensitive adhesive and is characterized by the fact that the pressure-sensitive adhesive comprises at least one resin soap. As has been shown, the domain size of the dispersed phases of such pressure-sensitive adhesives is significantly reduced, thus improving the compatibility of the (meth)acrylate phase with the synthetic rubber phase; in addition, the pressure-sensitive adhesives showed good adhesion and good cohesion.

[0013] According to the invention, an adhesive compound or pressure-sensitive adhesive is understood, as is common in general usage, to be a substance that is permanently sticky and adhesive, at least at room temperature. A characteristic of a pressure-sensitive adhesive is that it can be applied to a substrate by pressure and adheres there, whereby the pressure to be applied and the duration of this pressure are not defined in detail. Generally, however, depending on the exact type of pressure-sensitive adhesive and the substrate, as well as the temperature and humidity, the application of a short-term, minimal pressure, not exceeding a light touch for a brief moment, is sufficient to achieve the adhesive effect; in other cases, a longer duration of higher pressure may be necessary.

[0014] Pressure-sensitive adhesives possess special, characteristic viscoelastic properties that result in their permanent tackiness and bonding strength. A defining characteristic is that when mechanically deformed, both viscous flow processes and the development of elastic restoring forces occur. The relative proportions of these two processes depend on the precise composition, structure, and degree of cross-linking of the pressure-sensitive adhesive, as well as the rate and duration of deformation and the temperature.

[0015] The proportion of viscous flow is necessary to achieve adhesion. Only the viscous components, often caused by macromolecules with relatively high mobility, enable good wetting and flow onto the substrate to be bonded. A high proportion of viscous flow leads to high tack (also known as surface tack) and thus often also to high adhesion. Highly cross-linked systems, crystalline or glassy polymers, are generally not tacky or at least only slightly tacky due to a lack of flowable components.

[0016] The elastic restoring forces are necessary to achieve cohesion. They are generated, for example, by very long-chain and highly entangled macromolecules, as well as by physically or chemically cross-linked macromolecules, and enable the transmission of forces acting on an adhesive bond. This allows an adhesive bond to withstand a sustained load, such as continuous shear stress, to a sufficient degree over an extended period.

[0017] To describe and quantify the degree of elastic and viscous components, as well as their ratio, the storage modulus (G') and loss modulus (G''), which can be determined using Dynamic Mechanical Analysis (DMA), are used. G' is a measure of the elastic component, and G'' is a measure of the viscous component of a material. Both quantities depend on the deformation frequency and the temperature.

[0018] The parameters can be determined using a rheometer. The material under investigation is subjected, for example, to a sinusoidally oscillating shear stress in a plate-plate arrangement. In shear-stress controlled devices, the deformation is measured as a function of time, along with the time lag of this deformation relative to the application of the shear stress. This time lag is called the phase angle δ.

[0019] The storage modulus G' is defined as follows: G' = (τ / y) · cos(δ) (τ = shear stress, γ = deformation, δ = phase angle = phase shift between the shear stress and deformation vectors). The definition of the loss modulus G'' is: G'' = (τ / γ) · sin(δ) (τ = shear stress, γ = deformation, δ = phase angle = phase shift between the shear stress and deformation vectors).

[0020] A mass is considered to be an adhesive mass, and is defined as such within the meaning of the invention, particularly if it exhibits a deformation frequency of 10°C at 23°C. 0 up to 10 1 rad / sec both G' and G'' at least partially in the range of 10 3 up to 10 7 Pa lie. “Partly” means that at least a section of the G' or G'' curve lies within the window defined by the deformation frequency range including 10 0 up to and including 10 1 rad / sec (abscissa) and the range of G' and G'' values ​​including 10 3 up to and including 10 7 Pa (ordinate) is spanned.

[0021] A “poly(meth)acrylate” is understood to be a polymer obtainable by radical polymerization of acrylic and / or methacrylic monomers and optionally other copolymerizable monomers. In particular, a “poly(meth)acrylate” is understood to be a polymer whose monomer base consists of at least 50 wt.% acrylic acid, methacrylic acid, acrylic esters and / or methacrylic esters, wherein acrylic esters and / or methacrylic esters are present at least proportionally, preferably at least 30 wt.%, based on the total monomer base of the polymer in question.

[0022] Preferably, the adhesive compound according to the invention contains poly(meth)acrylate in a total of 40 to 60 wt.%, based on the total weight of the adhesive compound. It may contain one (single) poly(meth)acrylate or several poly(meth)acrylates.

[0023] The glass transition temperature of the poly(meth)acrylate of the adhesive compound according to the invention is preferably < 0 °C, more preferably between -20 and -50 °C.

[0024] Preferably, the poly(meth)acrylate of the pressure-sensitive adhesive according to the invention contains at least one partially polymerized functional monomer, particularly preferably one that is reactive with epoxy groups forming a covalent bond. Most preferably, the partially polymerized functional monomer, particularly preferably one that is reactive with epoxy groups forming a covalent bond, contains at least one functional group selected from the group consisting of carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, hydroxyl groups, acid anhydride groups, epoxy groups, and amino groups; in particular, it contains at least one carboxylic acid group. Most preferably, the poly(meth)acrylate of the pressure-sensitive adhesive according to the invention contains partially polymerized acrylic acid and / or methacrylic acid.All of the aforementioned groups exhibit reactivity with epoxy groups, which makes the poly(meth)acrylate advantageously susceptible to thermal crosslinking with incorporated epoxides.

[0025] The poly(meth)acrylate of the adhesive compound according to the invention can preferably be traced back to the following monomer composition: a) at least one acrylic acid ester and / or methacrylic acid ester of the following formula (1) CH2=C(R I )(COOR II ) (1), in which R I = H or CH3 and R II an alkyl group with 4 to 18 carbon atoms; b) at least one olefinically unsaturated monomer with at least one functional group selected from the group consisting of carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, hydroxyl groups, acid anhydride groups, epoxide groups and amino groups; c) optionally further acrylic acid esters and / or methacrylic acid esters and / or olefinically unsaturated monomers that can be copolymerized with component (a).

[0026] It is particularly advantageous to select the monomers of component a) with a proportion of 45 to 99 wt.%, the monomers of component b) with a proportion of 1 to 15 wt.% and the monomers of component c) with a proportion of 0 to 40 wt.%, the values ​​of which refer to the monomer mixture for the base polymer without the addition of any additives such as resins etc.

[0027] The monomers of component a) are generally plasticizing, rather nonpolar monomers. R'' in monomers a) is particularly preferred as an alkyl group with 4 to 10 carbon atoms, or 2-propylheptyl acrylate, or 2-propylheptyl methacrylate. The monomers of formula (1) are in particular selected from the group consisting of n-butyl acrylate, n-butyl methacrylate, n-pentyl acrylate, n-pentyl methacrylate, n-amyl acrylate, n-hexyl acrylate, n-hexyl methacrylate, n-heptyl acrylate, n-octyl acrylate, n-octyl methacrylate, n-nonyl acrylate, isobutyl acrylate, isooctyl acrylate, isooctyl methacrylate, 2-ethylhexyl acrylate, 2-propylheptyl acrylate and 2-propylheptyl methacrylate.

[0028] The monomers of component b) are particularly preferably selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, aconitic acid, dimethylacrylic acid, β-acrylic acid, trichloroacrylic acid, vinylacetic acid, vinylphosphonic acid, maleic anhydride, hydroxyethyl acrylate, in particular 2-hydroxyethyl acrylate, hydroxypropyl acrylate, in particular 3-hydroxypropyl acrylate, hydroxybutyl acrylate, in particular 4-hydroxybutyl acrylate, hydroxyhexyl acrylate, in particular 6-hydroxyhexyl acrylate, hydroxyethyl methacrylate, in particular 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, in particular 3-hydroxypropyl methacrylate, hydroxybutyl methacrylate, in particular 4-hydroxybutyl methacrylate, hydroxyhexyl methacrylate, in particular 6-hydroxyhexyl methacrylate, allyl alcohol, glycidyl acrylate, glycidyl methacrylate. Examples of monomers of component c) are:

[0029] Methylacrylat, Ethylacrylat, Propylacrylat, Methylmethacrylat, Ethylmethacrylat, Benzylacrylat, Benzylmethacrylat, sec-Butylacrylat, tert-Butylacrylat, Phenylacrylat, Phenylmethacrylat, Isobornylacrylat, Isobornylmethacrylat, tert-Butylphenylacrylat, tert-Butylaphenylmethacrylat, Dodecylmethacrylat, Isodecylacrylat, Laurylacrylat, n-Undecylacrylat, Stearylacrylat, Tridecylacrylat, Behenylacrylat, Cyclohexylmethacrylat, Cyclopentylmethacrylat, Phenoxyethylacrlylat, Phenoxyethylmethacrylat, 2-Butoxyethylmethacrylat, 2-Butoxyethylacrylat, 3,3,5-Trimethylcyclohexylacrylat, 3,5-Dimethyladamantylacrylat, 4-Cumylphenylmethacrylat, Cyanoethylacrylat, Cyanoethylmethacrylat, 4-Biphenylacrylat, 4-Biphenylmethacrylat, 2-Naphthylacrylat, 2-Naphthylmethacrylat, Tetrahydrofufurylacrylat, Diethylaminoethylacrylat, Diethylaminoethylmethacrylat, Dimethylaminoethylacrylat, Dimethylaminoethylmethacrylat, 3-Methoxyacrylsäuremethylester, 3-Methoxybutylacrylat, 2-Phenoxyethylmethacrylat,Butyldiglykolmethacrylat, Ethylenglycolacrylat, Ethylenglycolmonomethylacrylat, Methoxypolyethylenglykolmethacrylat 350, Methoxypolyethylenglykolmethacrylat 500, Propylenglycolmonomethacrylat, Butoxydiethylenglykolmethacrylat, Ethoxytriethylenglykolmethacrylat, Octafluoropentylacrylat, Octafluoropentylmethacrylat, 2,2,2-Trifluorethylmethacrylat, 1,1,1,3,3,3-Hexafluoroisopropylacrylat, 1,1,1,3,3,3-Hexafluoroisopropylmethacrylat, 2,2,3,3,3-Pentafluoropropylmethacrylat, 2,2,3,4,4,4-Hexafluorobutylmethacrylat, 2,2,3,3,4,4,4-Heptafluorobutylacrylat, 2,2,3,3,4,4,4-Heptafluorobutylmethacrylat, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Pentadecafluorooctylmethacrylat, Dimethylaminopropylacrylamid, Dimethylaminopropylmethacrylamid, N-(1-Methylundecyl)acrylamid, N-(n-Butoxymethyl)acrylamid, N-(Butoxymethyl)methacrylamid, N-(Ethoxymethyl)acrylamid, N-(n-Octadecyl)acrylamid; N,N-Dialkyl-substituierte Amide wie beispielsweise N,N-Dimethylacrylamid und N,N-Dimethylmethacrylamid; N-Benzylacrylamid,N-isopropylacrylamide, N-tert-butylacrylamide, N-tert-octylacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, acrylonitrile, methacrylonitrile; vinyl ethers such as vinyl methyl ether, ethyl vinyl ether, vinyl isobutyl ether; vinyl esters such as vinyl acetate; vinyl halides, vinylidene halides, vinylpyridine, 4-vinylpyridine, N-vinylphthalimide, N-vinyllactam, N-vinylpyrrolidone, styrene, α- and p-methylstyrene, α-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene, 3,4-dimethoxystyrene; Macromonomers such as 2-polystyrene ethyl methacrylate (weight-mean molecular weight Mw, determined by GPC, from 4000 to 13000 g / mol), poly(methyl methacrylate) ethyl methacrylate (Mw from 2000 to 8000 g / mol).

[0030] Monomers of component c) can advantageously be selected to contain functional groups that support subsequent radiochemical crosslinking (for example, by electron beams or UV radiation). Suitable copolymerizable photoinitiators include, for example, benzoin acrylate and acrylate-functionalized benzophenone derivatives. Monomers that support crosslinking by electron irradiation include, for example, tetrahydrofurfuryl acrylate, N-tert-butylacrylamide, and allyl acrylate.

[0031] The poly(meth)acrylates are preferably produced by conventional radical polymerizations or controlled radical polymerizations. The poly(meth)acrylates can be prepared by copolymerization of the monomers using standard polymerization initiators and, optionally, regulators, with polymerization taking place at standard temperatures in the solid form, in an emulsion (e.g., in water or liquid hydrocarbons), or in solution.

[0032] The poly(meth)acrylates are preferably produced by copolymerization of the monomers in solvents, particularly preferably in solvents with a boiling range of 50 to 150 °C, in particular of 60 to 120 °C, using 0.01 to 5 wt.%, in particular of 0.1 to 2 wt.%, in each case based on the total weight of the monomers, of polymerization initiators.

[0033] In principle, all common initiators are suitable. Examples of radical sources include 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) (DuPont Vazo® 67™) or 2,2'-azobis(2-methylpropionitrile) (2,2'-azobisisobutyronitrile; AIBN; DuPont Vazo® 64™).

[0034] Preferred solvents for the production of the poly(meth)acrylates are alcohols such as methanol, ethanol, n- and isopropanol, n- and isobutanol, in particular isopropanol and / or isobutanol; hydrocarbons such as toluene and in particular gasoline with a boiling range of 60 to 120°C; ketones, in particular acetone, methyl ethyl ketone, methyl isobutyl ketone; esters such as ethyl acetate; and mixtures of the aforementioned solvents. Particularly preferred solvents are mixtures containing isopropanol in amounts of 2 to 15 wt.%, in particular 3 to 10 wt.%, based on the solvent mixture used.

[0035] Preferably, after the production (polymerization) of the poly(meth)acrylates, a concentration step is carried out, and further processing of the poly(meth)acrylates is essentially solvent-free. The concentration of the polymer can take place in the absence of crosslinking agents and accelerators. However, it is also possible to add one of these classes of compounds to the polymer prior to concentration, so that the concentration then takes place in the presence of this substance(s).

[0036] After the concentration step, the polymers can be transferred to a compounder. If necessary, the concentration and compounding can also take place in the same reactor.

[0037] The weight-mean molecular weights M wThe molecular weight of the polyacrylates is preferably in the range of 20,000 to 2,000,000 g / mol; very preferably in the range of 100,000 to 1,500,000 g / mol, and most preferably in the range of 150,000 to 1,000,000 g / mol. It can be advantageous to carry out the polymerization in the presence of suitable polymerization regulators such as thiols, halogen compounds, and / or alcohols to achieve the desired average molecular weight.

[0038] The data on the number-mean molar mass M n and the weight-average molar mass M w This document refers to the well-known determination method by gel permeation chromatography (GPC). The determination is performed on 100 µl of clear-filtered sample (sample concentration 4 g / l). Tetrahydrofuran with 0.1 vol% trifluoroacetic acid is used as the eluent. The measurement is carried out at 25 °C.

[0039] A PSS-SDV type column, 5 µm, 10 is used as a pre-column. 3Å, 8.0 mm * 50 mm (Specifications here and below in the order: type, particle size, porosity, inner diameter * length; 1 Å = 10 -10 m) is used. For separation, a combination of columns of type PSS-SDV, 5 µm, 10 is used. 3 Å and 10 5 Å and 10 6 Columns measuring 8.0 mm x 300 mm (Polymer Standards Service; detection via Shodex RI71 differential refractometer) were used. The flow rate was 1.0 ml per minute. Calibration for poly(meth)acrylates was performed against PMMA standards (polymethyl methacrylate calibration), and for other materials (resins, elastomers) against PS standards (polystyrene calibration).

[0040] The poly(meth)acrylates preferably have a K-value of 30 to 90, particularly preferably of 40 to 70, measured in toluene (1% solution, 21 °C). The Fikentscher K-value is a measure of the molecular weight and viscosity of polymers.

[0041] The principle of the method is based on the capillary viscometric determination of the relative solution viscosity. For this purpose, the test substance is dissolved in toluene by shaking for thirty minutes to obtain a 1% solution. The flow time is measured in a Vogel-Ossag viscometer at 25 °C, and the relative viscosity of the sample solution is determined from this value relative to the viscosity of the pure solvent. The K-value can be read from tables according to Fikentscher [PE Hinkamp, ​​Polymer, 1967, 8, 381] (K = 1000 k).

[0042] Preferably, the poly(meth)acrylate of the pressure-sensitive adhesive according to the invention has a polydispersity PD < 4 and thus a relatively narrow molecular weight distribution. Compounds based on this have particularly good shear strength after crosslinking, despite their relatively low molecular weight. Furthermore, the lower polydispersity allows for easier processing from the melt, as the flow viscosity is lower compared to a more broadly distributed poly(meth)acrylate, while maintaining largely the same application properties. Narrowly distributed poly(meth)acrylates can advantageously be produced by anionic polymerization or by controlled radical polymerization methods, the latter being particularly suitable. Corresponding poly(meth)acrylates can also be produced via N-oxyles.Furthermore, atom transfer radical polymerization (ATRP) can be advantageously used for the synthesis of tightly divided poly(meth)acrylates, wherein monofunctional or difunctional secondary or tertiary halides are preferably used as initiators and Cu, Ni, Fe, Pd, Pt, Ru, Os, Rh, Co, Ir, Ag, or Au complexes are used for abstraction of the halides. RAFT polymerization is also suitable.

[0043] The poly(meth)acrylates of the adhesive compound according to the invention are preferably linked by linkage reactions - in particular in the sense of addition or substitution reactions. - crosslinked by the functional groups contained within them using thermal crosslinkers. Any thermal crosslinker can be used that - ensure a sufficiently long processing time so that no retardation occurs during the processing, especially the extrusion process, - as well as leading to a rapid re-crosslinking of the polymer to the desired degree of crosslinking at lower temperatures than the processing temperature, especially at room temperature.

[0044] One possible combination is polymers containing carboxy, amino, and / or hydroxy groups and isocyanates, particularly aliphatic or blocked isocyanates, such as trimerized isocyanates deactivated with amines, as crosslinking agents. Suitable isocyanates include, in particular, trimerized derivatives of MDI [4,4-methylenedi(phenyl isocyanate)], HDI [hexamethylene diisocyanate, 1,6-hexylene diisocyanate], and IPDI [isophorone diisocyanate, 5-isocyanato-1-isocyanatomethyl-1,3,3-trimethylcyclohexane].

[0045] Thermal crosslinkers are preferably used at a rate of 0.1 to 5 wt.%, in particular at a rate of 0.2 to 1 wt.%, based on the total amount of the polymer to be crosslinked.

[0046] Crosslinking via complexing agents, also known as chelates, is also possible. A preferred complexing agent is, for example, aluminum acetylacetonate.

[0047] Preferably, the poly(meth)acrylates of the pressure-sensitive adhesive according to the invention are cross-linked by means of epoxide(s) or by means of one or more substances containing epoxide groups. The substances containing epoxide groups are in particular multifunctional epoxides, i.e., those with at least two epoxide groups; accordingly, an indirect cross-linking of the building blocks of the poly(meth)acrylates bearing the functional groups occurs. The substances containing epoxide groups can be either aromatic or aliphatic compounds.

[0048] Excellent multifunctional epoxides are oligomers of epichlorohydrin, epoxy ethers of polyhydric alcohols, especially ethylene, propylene, and butylene glycols, polyglycols, thiodiglycols, glycerol, pentaerythritol, sorbitol, polyvinyl alcohol, polyallyl alcohol and similar compounds;Epoxy ethers of polyhydric phenols, in particular resorcinol, hydroquinone, bis-(4-hydroxyphenyl)methane, bis-(4-hydroxy-3-methylphenyl)methane, bis-(4-hydroxy-3,5-dibromophenyl)methane, bis-(4-hydroxy-3,5-difluorophenyl)methane, 1,1-bis-(4-hydroxyphenyl)ethane, 2,2-bis-(4-hydroxyphenyl)propane, 2,2-bis-(4-hydroxy-3-methylphenyl)propane, 2,2-bis-(4-hydroxy-3-chlorophenyl)propane, 2,2-bis-(4-hydroxy-3,5-dichlorophenyl)propane, 2,2-bis-(4-hydroxy-3,5-dichlorophenyl)propane, bis-(4-hydroxyphenyl)phenylmethane, bis-(4-hydroxyphenyl)phenylmethane, bis-(4-hydroxyphenyl)diphenylmethane, Bis (4-hydroxyphenyl)-4'-methylphenylmethane, 1,1-bis-(4-hydroxyphenyl)-2,2,2-trichloroethane, bis-(4-hydroxyphenyl)-(4-chlorophenyl)-methane, 1,1-bis-(4-hydroxyphenyl)-cyclohexane, bis-(4-hydroxyphenyl)-cyclohexylmethane, 4,4'-dihydroxydiphenyl, 2,2'-dihydroxydiphenyl, 4,4'-dihydroxydiphenylsulfone and their hydroxyethyl ethers; phenol-formaldehyde condensation products such as phenol alcohols and phenolaldehyde resins;S- and N-containing epoxides, for example N,N-diglycidylaniline and N,N'-dimethyldiglycidyl-4,4-diaminodiphenylmethane; as well as epoxides which have been prepared by conventional methods from polyunsaturated carboxylic acids or monounsaturated carboxylic acid esters of unsaturated alcohols; glycidyl esters; polyglycidyl esters which can be obtained by polymerization or copolymerization of glycidyl esters of unsaturated acids or which are available from other acidic compounds, for example from cyanuric acid, diglycidyl sulfide or cyclic trimethylenetrisulfone or its derivatives.

[0049] Very suitable ethers include, for example, 1,4-butanediol diglycid ether, polyglycerol 3-glycid ether, cyclohexanedimethyl ethanol diglycid ether, glycerol triglycid ether, neopentyl glycol diglycid ether, pentaerythritol triglycid ether, 1,6-hexanediol diglycid ether, polypropylene glycol diglycid ether, trimethylolpropane triglycid ether, pentaerythritol triglycid ether, bisphenol A diglycid ether and bisphenol F diglycid ether.

[0050] Other preferred epoxides are cycloaliphatic epoxides such as 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (UVACure1500).

[0051] The poly(meth)acrylates are preferably crosslinked using a crosslinker-accelerator system ("crosslinking system") to obtain better control over the processing time, crosslinking kinetics, and degree of crosslinking. The crosslinker-accelerator system preferably comprises at least one epoxy-containing substance as a crosslinker and at least one accelerator substance that accelerates crosslinking reactions using epoxy-containing compounds at temperatures below the melting temperature of the polymer to be crosslinked.

[0052] According to the invention, amines are particularly preferably used as accelerators. These are formally considered substitution products of ammonia; in the following formulas, the substituents are represented by "R" and comprise in particular alkyl and / or aryl groups. Amines that undergo no or only minor reactions with the polymers to be crosslinked are particularly preferred.

[0053] In principle, primary (NRH2), secondary (NR2H), and tertiary amines (NR3) can be chosen as accelerators, including those containing multiple primary, secondary, and / or tertiary amino groups. Particularly preferred accelerators are tertiary amines such as triethylamine, triethylenediamine, benzyldimethylamine, dimethylaminomethylphenol, 2,4,6-tris-(N,N-dimethylaminomethyl)phenol, and N,N'-bis(3-(dimethylamino)propyl)urea. Other preferred accelerators are multifunctional amines such as diamines, triamines, and / or tetramines, for example, diethylenetriamine, triethylenetetramine, and trimethylhexamethylenediamine.

[0054] Other preferred accelerators are amino alcohols, in particular secondary and / or tertiary amino alcohols, wherein in the case of several amino functionalities per molecule, preferably at least one, and particularly preferably all, amino functionalities are secondary and / or tertiary. Particularly preferred such accelerators are triethanolamine, N,N-bis(2-hydroxypropyl)ethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, 2-aminocyclohexanol, bis(2-hydroxycyclohexyl)methylamine, 2-(diisopropylamino)ethanol, 2-(dibutylamino)ethanol, N-butyldiethanolamine, N-butylethanolamine, 2-[Bis(2-hydroxyethyl)amino]-2-(hydroxymethyl)-1,3-propanediol, 1-[bis(2-hydroxyethyl)amino]-2-propanol, triisopropanolamine, 2-(dimethylamino)ethanol, 2-(diethylamino)ethanol, 2-(2-dimethylaminoethoxy)ethanol, N,N,N'-trimethyl-N'-hydroxyethylbisaminoethyl ether, N,N,N'-trimethylaminoethylethanolamine and N,N,N'-trimethylaminopropylethanolamine.

[0055] Other suitable accelerators include pyridine, imidazoles such as 2-methylimidazole and 1,8-diazabicyclo[5.4.0]undec-7-ene. Cycloaliphatic polyamines can also be used as accelerators. Phosphorus-based accelerators such as phosphines and / or phosphonium compounds, for example triphenylphosphine or tetraphenylphosphonium tetraphenylborate, are also suitable.

[0056] Quaternary ammonium compounds can also be used as accelerators; examples include tetrabutylammonium hydroxide, cetyltrimethylammonium bromide, and benzalkonium chloride.

[0057] The adhesive compound according to the invention further contains at least one synthetic rubber.

[0058] Preferably, the pressure-sensitive adhesive contains synthetic rubber in a total proportion of 20 to 40% by weight, based on the total weight of the adhesive. The pressure-sensitive adhesive according to the invention may contain one or more synthetic rubbers.

[0059] Preferably, the synthetic rubber of the adhesive compound according to the invention is a block copolymer with a structure AB, ABA, (AB) n , (AWAY) n X or (ABA) n X, wherein - the blocks A independently of each other for a polymer formed by polymerization of at least one vinyl aromatic; - die Blöcke B unabhängig voneinander für ein Polymer, gebildet durch Polymerisation von konjugierten Dienen mit 4 bis 18 C-Atomen und / oder Isobutylen, oder für ein teil- oder vollhydriertes Derivat eines solchen Polymers; - X for the remainder of a coupling reagent or initiator and - n represents an integer ≥ 2.

[0060] Insbesondere sind alle Synthesekautschuke der erfindungsgemäßen Haftklebmasse Blockcopolymere mit einem Aufbau wie vorstehend dargelegt. Die erfindungsgemäße Haftklebmasse kann somit auch Gemische verschiedener Blockcopolymere mit einem Aufbau wie vorstehend enthalten.

[0061] The preferred synthetic rubbers, also referred to as vinyl aromatic block copolymers, comprise one or more rubber-like blocks B (soft blocks) and one or more glass-like blocks A (hard blocks). The synthetic rubber of the pressure-sensitive adhesive according to the invention is particularly preferably a block copolymer with a structure AB, ABA, (AB)3X, or (AB)4X, wherein A, B, and X have the meanings given above. All synthetic rubbers of the pressure-sensitive adhesive according to the invention are block copolymers with a structure AB, ABA, (AB)3X, or (AB)4X, wherein A, B, and X have the meanings given above. In particular, the synthetic rubber of the pressure-sensitive adhesive according to the invention is a mixture of block copolymers with a structure AB, ABA, (AB)3X, or (AB)4X, preferably containing at least diblock copolymers AB and / or triblock copolymers ABA.

[0062] Block A is, in particular, a glassy block with a preferred glass transition temperature (Tg, DSC) that is above room temperature. The Tg of the glassy block is particularly preferably at least 40 °C, more preferably at least 60 °C, most preferably at least 80 °C, and most preferably at least 100 °C. The proportion of vinyl aromatic blocks A in the total block copolymers is preferably 10 to 40 wt.%, more preferably 20 to 33 wt.%. Vinyl aromatics for the construction of block A preferably comprise styrene and α-methylstyrene. Block A can thus be present as a homopolymer or copolymer. Block A is particularly preferably a polystyrene.

[0063] Block B is in particular a rubber-like block or soft block with a preferred Tg of less than room temperature. The Tg of the soft block is particularly preferably less than 0 °C, particularly less than -10 °C, for example less than -40 °C and most preferably less than -60 °C.

[0064] Preferred conjugated dienes as monomers for soft block B are selected in particular from the group consisting of butadiene, isoprene, ethylbutadiene, phenylbutadiene, piperylene, pentadiene, hexadiene, ethylhexadiene, dimethylbutadiene and the farnesene isomers, as well as any mixtures of these monomers. Block B can also exist as a homopolymer or as a copolymer.

[0065] Particularly preferred are the conjugated dienes selected from butadiene and isoprene as monomers for soft block B. For example, soft block B is a polyisoprene, a polybutadiene, or a partially or fully hydrogenated derivative of one of these two polymers, such as, in particular, polybutylenebutadiene; or a polymer of a mixture of butadiene and isoprene. Block B is most preferably a polybutadiene.

[0066] In the pressure-sensitive adhesive according to the invention, poly(meth)acrylate and synthetic rubber preferably exist separately as homogeneous phases – as is generally the case in such pressure-sensitive adhesives. The synthetic rubber is particularly preferably dispersed in the poly(meth)acrylate.

[0067] Preferably, the poly(meth)acrylates and synthetic rubbers contained in the pressure-sensitive adhesive are not miscible to homogeneity at 23°C. The pressure-sensitive adhesive according to the invention thus exists, at least microscopically and at least at room temperature, preferably in at least a two-phase morphology. Particularly preferably, the poly(meth)acrylate(s) and synthetic rubber(s) are not homogeneously miscible in a temperature range from -20°C to 90°C, and especially from 0°C to 60°C, so that the pressure-sensitive adhesive exists, at least microscopically, in at least a two-phase form in these temperature ranges.

[0068] For the purposes of this document, components are defined as "not homogeneously miscible" if, even after thorough mixing, the formation of at least two stable phases can be demonstrated physically and / or chemically, at least microscopically, with one phase being rich in one component and the other phase being rich in the other component. The presence of negligible amounts of one component in the other, which does not preclude the formation of multiphases, is considered irrelevant. Thus, small amounts of synthetic rubber and / or small amounts of the poly(meth)acrylate component may be present in the poly(meth)acrylate phase, provided these amounts are not significant enough to affect phase separation.

[0069] Phase separation can be achieved, in particular, by having discrete regions (“domains”) rich in synthetic rubber—i.e., composed essentially of synthetic rubber—within a continuous matrix rich in poly(meth)acrylate—i.e., composed essentially of poly(meth)acrylate. Scanning electron microscopy is, for example, a suitable analytical system for phase separation. Phase separation can also be demonstrated, for example, by the fact that the different phases exhibit two independent glass transition temperatures when measured by differential scanning calorimetry (DSC) or mechanical analysis (DMA). According to the invention, phase separation is present, in particular, if it can be clearly demonstrated by at least one of the analytical methods.

[0070] Within the synthetic rubber-rich domains, additional multiphase structure may also be present, with the A-blocks forming one phase and the B-blocks forming a second phase.

[0071] The adhesive compound according to the invention further comprises at least one resin soap.

[0072] A resin soap is understood to be the salt of a resin acid. "Resin acids" refers to carboxylic acids that belong to the acid spectrum underlying natural resins, as well as derivatives of these resin acids in which the carboxylic acid group remains free even after derivatization.

[0073] Natural resins are of plant origin, predominantly derived from trees, mainly conifers, and among these, especially pines. A resin soap can therefore also be defined as a salt of a possibly derivatized acid belonging to the acid spectrum underlying conifer resins.

[0074] The acid spectrum of conifer resins essentially comprises eight acids, which can be divided into abietine types and pimar types.

[0075] The abietin type includes: abietic acid, neoabietic acid, palustric acid, levopimaric acid and dehydroabietic acid.

[0076] Pimaric acid includes: pimaric acid, isopimaric acid and sandaracopimaric acid.

[0077] According to the invention, a resin soap can therefore also be defined as a salt of abietic acid, neoabietic acid, palustric acid, levopimaric acid, dehydroabietic acid, pimaric acid, isopimaric acid or sandaracopimaric acid, as well as a salt formed from their derivatives with a free acid group.

[0078] The derivatives of the resin acids are preferably the hydrogenated, dehydrated or disproportionated resin acids, in particular the hydrogenated or dehydrated resin acids.

[0079] The salts can contain various cations. Preferably, the resin soap contains a metal cation or an ammonium ion, particularly preferably a zinc, sodium, barium, aluminum, calcium, iron, or manganese cation, more preferably a zinc, sodium, or iron cation, in particular a zinc or sodium cation, and most preferably a zinc cation.

[0080] Preferably, the pressure-sensitive adhesive composition according to the invention comprises a mixture of several resin soaps, which as such can also be referred to by the singular "soap". Particularly preferably, the resin soap of the pressure-sensitive adhesive composition according to the invention is a rosin soap. In other words, the pressure-sensitive adhesive composition according to the invention particularly preferably comprises a mixture of several resin soaps, the underlying resin acids of which correspond to the acid profile of rosin.

[0081] Preferably, the adhesive compound according to the invention comprises one or more resin soaps in a total of 0.01 to 15 wt.%, particularly preferably in a total of 0.02 to 7.5 wt.%, in particular in a total of 2.0 to 7.0 wt.%, for example in a total of 3.0 to 6.5 wt.%, in each case based on the total weight of the adhesive compound.

[0082] In one embodiment, the adhesive compound according to the invention comprises one or more resin soaps totaling 0.01 to 0.1 wt.%, more preferably totaling 0.02 to 0.07 wt.%, in each case based on the total weight of the adhesive compound.

[0083] In a further embodiment, the adhesive compound according to the invention comprises one or more resin soaps in a total of 0.5 to 7.0 wt.%, more preferably in a total of 2.0 to 6.8 wt.%, in particular in a total of 3 to 6.5 wt.%, in each case based on the total weight of the adhesive compound.

[0084] In one embodiment, the adhesive compound according to the invention is foamed.

[0085] In this embodiment, the foaming of the adhesive matrix material can in principle be achieved in any conventional way, for example by an added propellant gas or by a chemical foaming agent that decomposes at a certain temperature during processing, forming gas.

[0086] Preferably, the pressure-sensitive adhesive is foamed using incorporated microballoons. "Microballoons" are defined as elastic, and therefore expandable in their ground state, hollow microspheres with a thermoplastic polymer shell. These spheres are filled with low-boiling liquids or liquefied gas. Polyacrylonitrile, PVDC, PVC, or polyacrylates are particularly suitable as shell materials. Commonly used low-boiling liquids include hydrocarbons of the lower alkanes, such as isobutane or isopentane, which are enclosed as a liquefied gas under pressure within the polymer shell.

[0087] When the microballoons are subjected to stress, particularly heat, the outer polymer shell softens. Simultaneously, the liquid propellant gas inside the shell transitions into a gaseous state. This causes the microballoons to expand irreversibly and three-dimensionally. The expansion ceases when the internal and external pressures equalize. Because the polymer shell remains intact, this process results in a closed-cell foam.

[0088] A wide variety of microballoon types are commercially available, differing primarily in their size (6 to 45 µm diameter in the unexpanded state) and the initial expansion temperatures required (75 to 220 °C). Unexpanded microballoon types are also available as aqueous dispersions with a solids or microballoon content of approximately 40 to 45 wt.%, and also as polymer-bonded microballoons (masterbatches), for example in ethylene vinyl acetate with a microballoon concentration of approximately 65 wt.%. Both the microballoon dispersions and the masterbatches, like the unexpanded microballoons, are suitable for producing a foamed pressure-sensitive adhesive according to the invention.

[0089] Foamed pressure-sensitive adhesives according to the invention can also be produced using so-called pre-expanded microballoons. In this group, the expansion takes place before the microballoons are mixed into the polymer matrix.

[0090] Furthermore, foamed pressure-sensitive adhesives according to the invention can also be produced with foamed particles, i.e., with expanded or expandable spheres made of, in particular, polystyrene, polypropylene, thermoplastic polyurethane, or cellulose acetate, for which the term "beads" has become established in English. Thus, particles made of already foamed plastics are mixed into the pressure-sensitive adhesive matrix, causing the reduction in density. The particles can also be added to the matrix without foaming and only then foamed.

[0091] The density of a foamed adhesive compound according to the invention is preferably 500 to 1000 kg / m³. 3 , preferably 600 to 990 kg / m³ 3 , especially 700 to 980 kg / m² 3 .

[0092] In one embodiment, the adhesive compound according to the invention is foamed, in particular by means of incorporated microballoons, and the adhesive compound comprises one or more resin soaps in total 0.01 to 0.1 wt.%, more preferably in total 0.02 to 0.07 wt.%, in each case based on the total weight of the adhesive compound.

[0093] The pressure-sensitive adhesive composition according to the invention preferably comprises at least one tackifier compatible with the poly(meth)acrylate, which can also be referred to as an adhesive strength enhancer or adhesive resin. According to the general understanding of those skilled in the art, a "tackifier" is understood to be an oligomeric or polymeric resin that increases the autoadhesion (the tack, the inherent stickiness) of the pressure-sensitive adhesive composition compared to an otherwise identical pressure-sensitive adhesive composition without a tackifier.

[0094] A "tackifier compatible with poly(meth)acrylate" is understood to be a tackifier that alters the glass transition temperature of the system obtained after thorough mixing of poly(meth)acrylate and tackifier compared to pure poly(meth)acrylate, whereby the mixture of poly(meth)acrylate and tackifier also only has a T g can be assigned. A tackifier incompatible with the poly(meth)acrylate would form two Ts in the system obtained after thorough mixing of poly(meth)acrylate and tackifier. g leading to, one of which would be assigned to the poly(meth)acrylate domain and the other to the resin domain. The determination of the T g In this context, the measurement is taken calorimetrically using DSC (differential scanning calorimetry).

[0095] The tackifier compatible with the poly(meth)acrylate preferably has a DACP value of less than 0 °C, very preferably of at most -20 °C, and / or preferably an MMAP value of less than 40 °C, very preferably of at most 20 °C. For the determination of DACP and MMAP values, reference is made to C. Donker, PSTC Annual Technical Seminar, Proceedings, pp. 149-164, May 2001.

[0096] A terpene phenolic resin or a rosin derivative is particularly preferred as a tackifier compatible with the poly(meth)acrylate, with rosin soaps being naturally excluded; in particular, this tackifier is a terpene phenolic resin. An adhesive compound according to the invention can also contain mixtures of several tackifiers. Among the rosin derivatives, rosin esters are preferred.

[0097] Preferably, an adhesive compound according to the invention contains tackifiers compatible with the poly(meth)acrylate in a total of 7 to 25 wt.%, particularly preferably in a total of 10 to 20 wt.%, in each case based on the total weight of the adhesive compound.

[0098] Preferably, the tackifier compatible with the poly(meth)acrylate is also compatible or at least partially compatible with the synthetic rubber, in particular with its soft block B, whereby the preceding definition of the term "compatible" applies accordingly. Polymer-resin compatibility depends, among other things, on the molar mass of the polymers or resins. Compatibility is better when the molar masses are lower. For a given polymer, it is possible that the low-molecular-weight components of the resin molar mass distribution are compatible with the polymer, but the higher-molecular-weight components are not. This is an example of partial compatibility.

[0099] The weight ratio of poly(meth)acrylate to synthetic rubber in the adhesive compound according to the invention is preferably from 1:1 to 3:1, in particular from 1.8:1 to 2.2:1.

[0100] The weight ratio of tackifier compatible with the poly(meth)acrylate to synthetic rubber in the adhesive compound according to the invention is preferably a maximum of 2:1, in particular a maximum of 1:1. At least this weight ratio is preferably 1:4.

[0101] In this context, the terms "poly(meth)acrylate", "synthetic rubber" and "tackifier" naturally refer to the entirety of all these components present in the adhesive compound.

[0102] The adhesive compound according to the invention particularly preferably contains a) 40 - 60 wt% of at least one poly(meth)acrylate, b) 20 - 40 wt% of at least one synthetic rubber, c) 7 - 25 wt% of at least one tackifier compatible with the poly(meth)acrylate, and d) 1 - 12 wt.% of at least one resin soap, each based on the total weight of the adhesive compound.

[0103] Depending on the area of ​​application and desired properties of the adhesive compound according to the invention, it can comprise further components and / or additives, either alone or in combination with one or more other additives or components.

[0104] The adhesive compound according to the invention can, for example, comprise powder and granular fillers, especially abrasive and reinforcing fillers, dyes and pigments such as chalk (CaCO3), titanium dioxide, zinc oxides and / or carbon black.

[0105] The adhesive compound according to the invention preferably comprises one or more chalks as a filler. The adhesive compound according to the invention preferably comprises chalk in a total proportion of up to 20% by weight. At such proportions, essential adhesive properties such as shear strength at room temperature and immediate tack to steel and PE are practically unaffected by the addition of the filler. Furthermore, various organic fillers may be included.

[0106] Suitable additives for the adhesive compound according to the invention are also - independent of other additives - non-expandable polymer hollow spheres, polymer solid spheres, glass hollow spheres, glass solid spheres, ceramic hollow spheres, ceramic solid spheres and / or carbon solid spheres ("Carbon Micro Balloons").

[0107] Furthermore, the adhesive compound according to the invention can comprise flame-retardant fillers, for example ammonium polyphosphate; electrically conductive fillers, for example conductive carbon black, carbon fibers and / or silver-coated spheres; thermally conductive materials, for example boron nitride, aluminum oxide, silicon carbide; ferromagnetic additives, for example iron(III) oxides; organic, renewable raw materials, for example wood flour; organic and / or inorganic nanoparticles; fibers, compounding agents, antioxidants, light stabilizers and / or ozone stabilizers.

[0108] Optional umfasst die erfindungsgemäße Haftklebmasse einen oder mehrere Weichmacher. Als Weichmacher können zB (Meth)Acrylat-Oligomere, Phthalate, Kohlenwasserstoff-Öle, Cyclohexandicarbonsäureester, wasserlösliche Weichmacher, Weichharze, Phosphate oder Polyphosphate enthalten sein.

[0109] The pressure-sensitive adhesive composition according to the invention preferably comprises silicas, particularly preferably precipitated silica, especially precipitated silica surface-modified with dimethyldichlorosilane. Advantageously, the thermal shear strength of the pressure-sensitive adhesive composition can be adjusted with this additive.

[0110] An adhesive compound according to the invention may, in addition to the components listed above, contain one or more hydrocarbon resins that are incompatible with the poly(meth)acrylate. Such hydrocarbon resins, which are also tackifiers, preferably comprise hydrogenated polymers of dicyclopentadiene; non-, partially, selectively, or fully hydrogenated hydrocarbon resins based on C5, C5 / C9, or C9 monomer streams; and polyterpene resins based on α-pinene and / or β-pinene and / or δ-limonene. The hydrocarbon resins preferably have a DACP value of at least 0 °C, very preferably at least 20 °C, and / or preferably an MMAP value of at least 40 °C, very preferably at least 60 °C. For the determination of DACP and MMAP values, please refer to C. Donker, PSTC Annual Technical Seminar, Proceedings, pp. 149-164, May 2001.The aforementioned hydrocarbon resins can be included in the pressure-sensitive adhesive either individually or in a mixture. Particularly preferred hydrocarbon resins are polyterpene resins based on α-pinene and / or β-pinene and / or δ-limonene.

[0111] The thickness of a web-shaped adhesive compound according to the invention is preferably 50 to 1500 µm, particularly preferably 70 to 1200 µm, in particular 100 to 800 µm, for example 150 µm to 500 µm or 200 µm to 400 µm.

[0112] The pressure-sensitive adhesive according to the invention can generally be produced in any desired manner, but it is preferably produced from the melt. A process for producing the pressure-sensitive adhesive according to the invention therefore preferably first comprises concentrating the poly(meth)acrylate solution or dispersion resulting from the polymer production. The concentration of the polymer can be carried out in the absence of crosslinking agents and accelerators. However, it is also possible to add at most one of these substances to the polymer prior to concentration, so that the concentration then takes place in the presence of this substance.

[0113] The production of the pressure-sensitive adhesive preferably further comprises passing it through a compounding and extrusion unit. The unit optionally used to concentrate the compound may or may not be part of this compounding and extrusion unit. At the latest after passing through the compounding and extrusion unit, the pressure-sensitive adhesive preferably exists as a melt; more preferably, the pressure-sensitive adhesive is already in the melt state during its passage through the compounding and extrusion unit.

[0114] The synthetic rubber, preferably together with a poly(meth)acrylate-compatible resin, is fed into the compounding and extrusion apparatus via a solid feeder. The concentrated and optionally already molten poly(meth)acrylate is preferably introduced into the compounding and extrusion apparatus via a so-called side feeder. In particular embodiments of the process, it is also possible for concentration and compounding to take place in the same reactor. Poly(meth)acrylate-compatible or other resins can optionally also be supplied via a resin melt and another side feeder at a different process position, e.g., after the introduction of synthetic rubber and poly(meth)acrylate.

[0115] Other additives and / or plasticizers can also be added as solids or melts, or as a batch in combination with another formulation component.

[0116] An extruder is used, in particular, as a compounding and extrusion device, or at least as a component thereof. The polymers are preferably present in the compounding and extrusion device in a melt state, either because they are introduced already in the melt state or by being heated to the melt within the compounding and extrusion device. Advantageously, the polymers are kept in the melt state within the compounding and extrusion device by heating.

[0117] If accelerators are used for crosslinking the poly(meth)acrylate, they are preferably added to the pressure-sensitive adhesive shortly before further processing after compounding, particularly shortly before coating or other shaping. The timing of the addition before coating depends primarily on the available pot life, i.e., the processing time in the melt, without adversely affecting the properties of the resulting product.

[0118] The crosslinkers, for example epoxides, and optionally the accelerators, can both be added shortly before further processing of the composition, advantageously in the phase described above for the accelerators. For this purpose, it is advantageous if the crosslinker and accelerator are introduced into the process simultaneously at the same point, optionally as an epoxy-accelerator mixture. In principle, it is also possible to reverse the addition times or points for the crosslinker and accelerator in the configurations described above, so that the accelerator can be added before the crosslinking agents.

[0119] The adhesive compound is preferably dispensed from the compounding and extrusion device through a nozzle.

[0120] After mixing or compounding and dispensing the finished pressure-sensitive adhesive, the adhesive is preferably formed into a web; this is done particularly in a calender gap. The coating calenders can consist of two, three, four, or more rollers.

[0121] Preferably, at least one of the rollers is provided with an anti-adhesive surface. Particularly preferably, all rollers of the calender that come into contact with the adhesive are equipped with an anti-adhesive surface. A steel-ceramic-silicone composite material is preferably used as the anti-adhesive surface. Such roller surfaces are resistant to thermal and mechanical stresses.

[0122] It has proven particularly advantageous to use roller surfaces with a surface structure such that the surface does not come into complete contact with the layer of material being processed, thus reducing the contact area compared to a smooth roller. Structured rollers, such as metal anilox rollers (e.g., steel anilox rollers), are especially beneficial.

[0123] The coating can be applied to a temporary carrier. This temporary carrier is removed during further processing, for example, during tape assembly or application, by removing the adhesive layer. The temporary carrier is preferably a release liner. The adhesive can also be coated on both sides with either a temporary carrier or a release liner.

[0124] Also disclosed is an adhesive tape containing at least one layer of an adhesive compound according to the invention.

[0125] Preferably, the adhesive tape consists of a layer of an adhesive compound according to the invention. In this case, it is a so-called transfer adhesive tape. However, the adhesive compound can also be present as the carrier layer of a single- or double-sided adhesive tape or form at least one of the adhesive outer layers of a carrier-containing single- or double-sided adhesive tape. A release liner, such as is usually applied to adhesive compounds for their (temporary) protection, is not considered a component of the adhesive tape in this case. Accordingly, the adhesive tape can consist solely of a layer of an adhesive compound according to the invention, even if this layer is covered with a release liner.

[0126] The use of resin soap in the production of pressure-sensitive adhesives is also revealed. As shown above, the resin soap is used as a component in the formulation of these adhesives. Examples of measurement and testing methods: Dynamic differential calorimetry (glass transition temperature, measurement method 1):

[0127] The glass transition temperature of polymers or polymer blocks in block copolymers is determined according to the invention using differential scanning calorimetry (DSC). For this purpose, approximately 5 mg of an untreated polymer sample is weighed into an aluminum crucible (volume 25 µl) and sealed with a perforated lid. A Netzsch DSC 204 F1 is used for the measurement. The instrument is operated under nitrogen for inerting. The sample is first cooled to -150 °C, then heated to +150 °C at a rate of 10 K / min and cooled again to -150 °C. The subsequent second heating cycle is also performed at 10 K / min, and the change in heat capacity is recorded. Glass transitions are represented as steps in the thermogram (heat flow-temperature diagram, see [reference]). Fig. 1) identified. The glass transition temperature T g is obtained as follows (see Figure 1):

[0128] The linear portions of the measurement curve before and after the step are extended in the direction of increasing (before the step) and decreasing (after the step) temperatures, respectively (extension lines ① and ②). Within the step, a regression line ⑤ is placed parallel to the ordinate such that it intersects the two extension lines, creating two areas ③ and ④ (between the respective extension lines, the regression line, and the measurement curve) of equal area. The intersection of this regression line with the measurement curve yields the glass transition temperature. Determination of the size of the synthetic rubber domains in the polyacrylate synthetic rubber blends (measurement method 2):

[0129] A reduced size of the synthetic rubber domains indicates improved compatibility between polyacrylate and synthetic rubber. To determine the domain sizes, platinum-sputtered samples were measured using a scanning electron microscope (LEO / Zeiss 1530). The samples were refracted under liquid nitrogen and contrasted with OsO4.

[0130] The evaluation was performed at 3,000x magnification using the image analysis software ImageJ. Adhesion strength 180° (test method 1):

[0131] The adhesive strength on steel, polyethylene (PE) and polycarbonate (PC) was determined under a test climate of 23 °C + / - 1 °C temperature and 50 % + / - 5 % relative humidity.

[0132] A 20 mm wide strip of the adhesive tape sample was applied to the substrate plate, which had previously been washed twice with acetone and once with isopropanol (steel) or twice with isopropanol (PE, PC), and then left to air dry for 5 minutes to allow the solvent to evaporate. The adhesive strip was pressed onto the substrate twice with a pressure equivalent to a weight of 2 kg. The tape was then immediately peeled off the substrate at a speed of 300 mm / min and at an angle of 180°. The measurement results are given in N / cm and are averaged from three measurements. Static shear test / shear resistance time (test method 2):

[0133] The shear strength was determined under a test climate of 23 °C + / - 1 °C temperature and 50 % + / - 5 % relative humidity.

[0134] The test samples were cut to a width of 13 ± 0.2 mm and stored in a controlled environment for at least 16 hours. For the test, 50 x 25 mm ASTM steel plates, 2 mm thick and with a 20 mm marking line, were used. These plates were thoroughly cleaned several times with acetone before bonding and then allowed to dry for 1–10 minutes. The bonding area was 13 x 20 ± 0.2 mm. The test strip was applied to the substrate by smoothing it lengthwise with a wiper, ensuring that the upper edge of the test sample was precisely aligned with the 20 mm marking line, thus avoiding air bubbles.

[0135] The back of the test sample was covered with aluminum foil. The exposed end was then covered with paper. The adhesive strip was then rolled back and forth twice with a 2 kg roller. After rolling, a webbing loop (weighing 5-7 g) was attached to the exposed end of the adhesive tape.

[0136] Next, an adapter plate was attached to the front of the shear test plate using a screw and nut. To ensure that the adapter plate was firmly seated on the plate, the screw was tightened firmly by hand.

[0137] The prepared plate was attached to a counter via the adapter plate using a hook; a 1 kg weight was then hung smoothly in the strap loop.

[0138] The setup time between rolling and loading was 12 minutes. The time in minutes until the adhesive bond failed was measured; the measurement results are averaged from three measurements. Microshear travel (MSW, test method 3):

[0139] Following ASTM D 4498, the procedure is as follows: A 50 µm thick sample of the adhesive is coated on one side with a 50 µm thick aluminum foil for stabilization. A test strip 10 mm wide and 50 mm long is bonded to a clean steel plate, creating a bonding area of ​​130 mm². 2The adhesive bond is created by rolling a 2 kg roll back and forth three times. The steel plate is adjusted in the measuring apparatus so that the test strip is in a vertical position and is heated to 30 °C. The system is then heated to 40 °C. To start the measurement, a 25 g weight is attached to the free end of the test strip using a clamp (6.4 g), which applies a shear load to the sample by gravity. Simultaneously, a micrometer probe is placed on a short section of the test strip that extends beyond the steel plate. This probe records the deflection as a function of the measurement time, or the shear displacement is graphically recorded. The maximum microshear displacement ("max") is the shear distance after a weight load of 15 minutes. After this measurement time, the weight is carefully removed from the sample, and the relaxation is then observed for another 15 minutes.After this relaxation time, the microshear displacement S2 (relaxed microshear displacement) is determined. From the two measured values, the microshear displacement quotient E = S2 / S1 (elastic component) is calculated. This quotient E is a measure of the elasticity (restoring force) of the adhesive compound. Name Plate Test (Test Method 4):

[0140] A magnesium test strip measuring 2 cm wide, 15 cm long, and 0.5 mm thick was washed with acetone and left to stand for 5 minutes at a temperature of 23 °C ± 1 °C and a relative humidity of 50% ± 5%. The magnesium strip was then applied lengthwise to the adhesive tape pattern. Excess tape was then trimmed so that it was flush with the magnesium strip.

[0141] A 20 cm long, 2.5 cm wide, and 3 mm thick polycarbonate sheet (PC sheet) was washed with ethanol and left to stand for 120 minutes at a temperature of 23 °C ± 1 °C and a relative humidity of 50% ± 5%. The composite of the magnesium strip and the adhesive tape was glued to the center of the PC sheet, thus creating the test sample. A defined bond was ensured by rolling over the sheet five times with a double roller using a 4 kg roller and then allowing it to stand for 72 hours.

[0142] The PC board with the adhesive composite of tape pattern and magnesium strips was clamped into a 33° NPT frame, the structure of which was built in the Fig. 2 and Fig. 3 is shown. Fig. Figure 2 shows a cross-section of the frame, which has a curved metal plate 6. The dimensions labeled a, b, and c have the following meanings: a = 211 mm; b = 28 mm; c = 6 mm.

[0143] The size of the angle α is 33°.

[0144] How Fig. As further illustrated in Figure 3, the frame essentially consists of a curved metal plate, 6 laterally mounted fixing rails 7, and adjusting screws 8. The PC plate was clamped transversely into the frame so that its ends were flush with the fixing rail on the frame, and the bonded magnesium strip was visibly pointing upwards without any fixing. The frame was then placed in an oven at 50°C. After 1, 24, and 48 hours, the distance between both ends of the magnesium test strip was measured at a 90° angle to the PC plate. The measurement result is the sum of both measured distances and is given in mm. A duplicate measurement was performed, and the average was calculated.

[0145] The measurement results are interpreted as follows: ≤ 5 mm: advantageous < 10 mm: still satisfactory ≥ 10 mm: unsatisfactory. Production of polyacrylate 1:

[0146] A conventional reactor for radical polymerizations was filled with 68.0 kg of 2-ethylhexyl acrylate, 25.0 kg of methyl acrylate, 7.0 kg of acrylic acid, and 66.6 kg of acetone / isopropanol (94:6). After 45 minutes of nitrogen gas purging with stirring, the reactor was heated to 58 °C and 50 g of AIBN dissolved in 500 g of acetone was added. The external heating bath was then heated to 75 °C, and the reaction was carried out at this constant temperature. After 1 h, another 50 g of AIBN dissolved in 500 g of acetone was added, and after 4 h, the mixture was diluted with 10 kg of acetone / isopropanol (94:6).

[0147] After 5 h and again after 7 h, the reaction was restarted with 150 g of bis-(4-tert-butylcyclohexyl)peroxydicarbonate dissolved in 500 g of acetone. After 22 h of reaction time, the polymerization was stopped and the product was cooled to room temperature. The product had a solids content of 55.8% and was dried. The resulting polyacrylate had a K-value of 51.3 and a weight-average molecular weight of M. w = 676,000 g / mol, a polydispersity of D (M w / M n ) = 9.5. Production of polyacrylate 2:

[0148] The preparation of polyacrylate 1 was carried out using the following monomer composition: 47.0 kg n-butyl acrylate, 30.0 kg 2-phenoxyethyl acrylate, 20.0 kg methyl acrylate and 3.0 kg acrylic acid.

[0149] The product was not dried, but diluted with ethyl acetate to a solids content of 35%. Examples 1-10 (based on polyacrylate 1):

[0150] The pressure-sensitive adhesives were produced in a hot-melt mixer from Werner & Pfleiderer. The hot-melt mixer was equipped with Z-hooks, which allowed the input substances to be mixed under shear. Additionally, the mixing chamber was heated to the desired temperature by an oil bath using a thermostat (Lauda LTH303).

[0151] The kneader was heated to 180 °C. Once this temperature was reached, the synthetic rubber (Kraton® 1118 ES), one-third of the adhesive resin (Dertophene® DT105), and the resin soap (see Table 1) were added to the kneading chamber and kneaded for 20 minutes. After adding the remaining two-thirds of the resin, kneading continued for another 5 minutes. The first addition of polyacrylate (one-fifth, Polyacrylate 1) was then made, and the target temperature was simultaneously reduced to 120 °C. During the cooling process, the remaining fifths of the polyacrylate were added to the kneading chamber at five-minute intervals. After the final addition of polyacrylate, kneading continued for another 35 minutes at 120 °C. The total kneading time was therefore approximately 80 minutes.

[0152] The composition of the manufactured pressure-sensitive adhesives is given in Table 1.

[0153] The masses produced in this way were processed into test samples using a hot press (Laufer company). The hot press had a chamber with two heated press plates (40 x 40 cm) and could generate a maximum force of 235 bar (equivalent to 270 kN).

[0154] The press was preheated to 120 °C, and the pressure range was set to 25 to 250 kN. The lower platen of the press was covered with release paper for protection. A 32 µm thick etched PET carrier film was placed on the release paper, followed by the material to be pressed and the spacers. Everything was then covered with another layer of release paper.

[0155] Eight grams of the respective pressure-sensitive adhesive, along with the release paper and backing material, were placed between the press plates. Two strips of release paper (80 µm thick) were used as spacers. The press was almost completely closed, so that no pressure was yet exerted on the adhesive, but the materials could no longer shift. The vent valve was closed and the vacuum pump switched on until a vacuum of 0.6 bar was established. The press was then completely closed. A pressing force of 220 kN was applied for three minutes. After this time, the press was opened just enough to relieve all pressure on the material. The vent valve was carefully opened until normal pressure was restored; then the press was fully opened and the sample removed.

[0156] Five samples of each pressure-sensitive adhesive were produced and then tested at five different locations using a thickness gauge. The resulting layer thickness of the samples was 100 µm. The samples were stored at room temperature. Table 1: Composition of the pressure-sensitive adhesive samples, examples 1-10 Nr. Polyacrylate 1 (wt%) Kraton® 1118 ES (wt%) Dertophene® DT105 (wt%) Resin soap (type; wt.%) Denka® TH-21 1(V) 53,3 30,3 16,4 - - 2(V) 52,9 30,0 16,3 - 0,8 3 52,9 30,0 16,3 Bremazit® 3050;0.8 - 4 51,2 29,1 15,7 Bremazit® 3050;4,0 - 5 50,0 28,4 15,4 Bremazit® 3050;6,3 - 6 52,0 29,6 16,0 Sylvaros® DRS 731;2,4 - 7 50,0 28,4 15,4 Sylvaros® DRS 731;6,3 - 8 52,0 29,6 16,0 Al-Resinate;2,4 - 9 52,9 30,0 16,3 Fe resinate; 0.8 - 10 51,2 29,1 15,7 Fe resinate; 4.0 - (V) - Comparative example Bremazit® 3050 - Zn resinate (Rokra-Kraemer) Sylvaros® DRS 731 - Na resinate (Arizona) Al and Fe resinate from City Chemical Table 2: Results for pressure-sensitive adhesives 1-10 Nr. Domain size (µm) 2 ) Adhesive strength (N / cm) Shear life (min) Microshear pathway Steel PE max (µm) elastic component (%) 1(V) 9,1 10,4 3 66 210 18 2(V) 5,9 - - - - - 3 6,2 10,2 3,6 108 198 22 4 1,5 11,7 4,5 1.374 113 36 5 1,8 11,9 4,5 6.110 39 68 6 8,1 10,2 4,1 178 157 30 7 1,8 10,2 2,1 795 84 48 8 5,9 10,9 3,9 149 223 38 9 2,6 9,9 2,0 283 95 31 10 2,3 10,9 2,2 3.242 52 35 (V) - Comparative trial Examples 11-15 (based on polyacrylate 2):

[0157] In examples 11 to 15, foamed pressure-sensitive adhesives were produced.

[0158] The dispersion obtained from the production of polyacrylate 2 was used as the polyacrylate component.

[0159] The synthetic rubber component was a mixture of 11.6 wt% Kraton® D1118 and 5.9 wt% Kraton® D1116 in 32.5 wt% gasoline and 32.5 wt% ethyl acetate, containing 17.5 wt% of the adhesive resin Dercolyte® A 115 (DRT).

[0160] The polyacrylate component and the synthetic rubber component mixed with the adhesive resin were dissolved separately overnight in the solvent using a roller bench; the solutions were then combined according to the polyacrylate:synthetic rubber ratio specified in Table 3, based on the solids content, and homogenized again for 8 h as thoroughly as possible using a roller bench.

[0161] Subsequently, unexpanded microballoons (Expancel® 920DU20, Nouryon) were added to the solution as a suspension in acetone while stirring, followed by a black pigment (Hostatint® Black AN 100, Clariant), also suspended in acetone and stirred.

[0162] While stirring further, an epoxy crosslinker (Erisys® GA-240, Emerald Performance Materials) and the resin soap (Bremazit® 3050, Rokra-Kraemer) were finally added.

[0163] The mixture was stirred for another 30 minutes, then the solutions were formed into a sheet using a spreading bar and dried for 10 minutes at 105 °C. Afterwards, it was foamed for 30 seconds at 170 °C.

[0164] The application weight of the materials was 180 g / m². 2 The resulting layer thickness was 200 µm. Table 3: Composition of the pressure-sensitive adhesive samples, examples 11-15 Nr. Polyacrylate / synthetic rubber (total wt.%; wt. ratio) Dercolyte® A 115% w / w Microballoons (wt%) Erisys® GA-240 (wt%) Bremazit® 3050 (wt%) Hostatint® Black AN 100 (% by weight) 11 78;3:1 19,5 0,72 0,04 0,04 1,95 12 82,7;14:3 14,6 0,72 0,04 0,04 1,9 13 87,5;8:1 9,7 0,72 0,04 0,04 2,0 14(V) 97,2;100:0 0 0,72 0,04 0,04 2,0 15(V) 48,6;0:100 48,6 0,72 0,04 0,04 2,0 (V) - Comparative trial Table 4: Results for pressure-sensitive adhesives 11-15 Nr. Adhesive strength of steel (N / cm) Adhesive strength PC (N / cm) Name-Plate Al / PC(mm / 48 h) Name-Plate Mg / PC(mm / 48 h) 11 10,7 11,7 1 0 12 11,2 11,7 2 1 12 8,9 11 2 1 14(V) 7,4 8,7 15 35 15(V) 10,5 9,4 35 35

Claims

[1] Adhesive compound comprising: a) one or more poly(meth)acrylates totaling 35 to 65 wt.%, and b) one or more synthetic rubbers in a total of 15 to 45 wt.%, based on the total weight of the adhesive compound, characterized by that the adhesive compound comprises at least one resin soap. [2] Adhesive compound according to claim 1, characterized by that the adhesive compound comprises at least one tackifier compatible with the poly(meth)acrylate. [3] Adhesive compound according to one of claims 1 and 2, characterized by that the resin soap contains a metal cation. [4] Adhesive compound according to any one of the preceding claims, characterized by that the resin side contains a zinc, sodium, or iron cation. [5] Adhesive compound according to any one of the preceding claims, characterized by that the resin soap is a rosin soap. [6] Adhesive compound according to any one of the preceding claims, characterized bythat the pressure-sensitive adhesive comprises one or more resin soaps totaling 0.01 to 15 wt.%, based on the total weight of the pressure-sensitive adhesive.

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