Poly(METH)acrylates, pressure-sensitive adhesive compounds, and method for the production thereof

Abstract

The present invention relates to poly(meth)acrylates which are produced by bulk polymerisation using a first polymerisation regulator and a second polymerisation regulator. The invention further relates to a pressure-sensitive adhesive compound and to the method for producing the poly(meth)acrylate pressure-sensitive adhesive compound.

Description

[0001] tesa SE

[0002] Norderstedt

[0003] Poly(meth)acrylates, pressure-sensitive adhesives and their manufacturing processes

[0004] The present invention relates to poly(meth)acrylates, in particular with high weight-average molecular weight, pressure-sensitive adhesives and the production of pressure-sensitive adhesives.

[0005] Poly(meth)acrylate adhesives are very frequently used in industrial pressure-sensitive adhesive tape applications. Poly(meth)acrylates offer several advantages over other elastomers. They are very stable against UV light, oxygen, and ozone. Synthetic and natural rubber adhesives mostly contain double bonds, which make these adhesives unstable against the aforementioned environmental influences. Another advantage of poly(meth)acrylates is their transparency and their suitability for use over a relatively wide temperature range.

[0006] In the bulk polymerization of (meth)acrylates to poly(meth)acrylates with high molar masses, e.g., weight-average molecular weights of more than 500,000 g / mol, and high conversion rates, transfer reactions to the already formed polymer lead to gel formation. The gel thus formed exhibits undesirable properties such as defects, thick spots, or optical inhomogeneities, and in a subsequent coating process, it forms pressure-sensitive adhesive layers.

[0007] A common countermeasure against chain transfer reactions to already formed macromolecules or polymers is the addition of a polymerization regulator (also called a regulator, chain transfer regulator, or carrier) during the polymerization process. Typical polymerization regulators include thiols such as isooctylthioglycolate (IOTG) or tetrabromomethane (CBr4). Highly active carriers, i.e., carriers with high transfer constants, have the disadvantage of severely limiting the maximum molecular weight and being rapidly consumed during the polymerization reaction. This means that highly active carriers typically have to be added to the already ongoing polymerization reaction, thus increasing the complexity of the polymerization process. Without such additional additions, the maximum molecular weight of the polymer is limited.Alternatively, gelation must be tolerated, which negatively impacts further processing. Publication KR 10 2012 0 050 068 A discloses a composition for optical fiber plates comprising an acrylic syrup. This syrup is produced by a multi-stage bulk polymerization process. In the first step, a mixture of acrylic monomers and a chain transfer regulator (dodecyl mercaptan) is added to precisely control the molecular weight of the polymer. Polymerization occurs after the addition of a thermal initiator, which is previously dissolved in ethyl acetate. Ethyl acetate serves solely as a solvent and carrier to improve handling and homogeneous distribution of the initiator.

[0008] Document US 2016 / 0185884 A1 describes a process for producing a methacrylate polymer composition by means of a two-stage, continuous bulk polymerization. A chain transfer regulator is used to adjust the molecular weight; in the exemplary embodiments, this is specifically n-octyl mercaptan. Additionally, stearyl alcohol is added, the function of which is explicitly described as a mold release agent to improve demoldability. The document thus teaches two clearly separate functions: mercaptan as a polymerization regulator and stearyl alcohol as a processing aid.

[0009] There is a need for poly(meth)acrylates that can be polymerized by an essentially solvent-free polymerization process, with high weight-average molecular weight, low gel content, and that can be processed into pressure-sensitive adhesives and are particularly suitable for the production of thin pressure-sensitive adhesive layers.

[0010] The object of the invention is therefore to provide poly(meth)acrylates by substance polymerization which do not have the disadvantages of the aforementioned prior art or only to a reduced extent.

[0011] Surprisingly, it was found that the use of two different polymerization regulators has a beneficial effect on the essentially solvent-free polymerization of poly(meth)acrylates suitable for pressure-sensitive adhesives. In particular, high molecular weights can be achieved during polymerization with low gel content. This enables the production of a virtually gel-free pressure-sensitive adhesive and its coating, especially with low application rates. Furthermore, polymerization can proceed without the need to add another polymerization regulator after the polymerization has started, making it particularly suitable for batch processes.

[0012] A first and general object of the invention, with which the problem is solved, is thus a poly(meth)acrylate which is produced by a substance polymerization, characterized in that the substance polymerization is carried out using a first polymerization regulator and a second polymerization regulator.

[0013] The first object of the invention is in particular a poly(meth)acrylate produced by a substance polymerization using a first polymerization regulator and a second polymerization regulator structurally different from the first, characterized in that the combination of the polymerization regulators serves to suppress the formation of gel and at the same time to enable the production of poly(meth)acrylates with a weight-average molecular weight of more than 500,000 g / mol without the need for a subsequent addition of a polymerization regulator after the start of polymerization.

[0014] Details and embodiments of the invention are described below. Such embodiments, which are subsequently designated as preferred in any way, are combined in particularly preferred embodiments with features of other embodiments also designated as preferred in any way. Combinations of two or more of the embodiments subsequently designated as particularly preferred in any way are therefore especially preferred. Also preferred are embodiments in which a feature of one embodiment designated as preferred in any way is combined with one or more further features of other embodiments designated as preferred in any way.

[0015] Insofar as specific quantities or proportions of an element as well as preferred embodiments of the element are disclosed below, the specific quantities or proportions of the preferably embodiments are also disclosed. Furthermore, it is disclosed that, among the corresponding specific total quantities or proportions of the elements, at least some of the elements may be preferably embodiments, and in particular, that preferably embodiments may, in turn, be present within the specific total quantities or proportions.

[0016] Poly(meth)acrylate

[0017] The term "poly(meth)acrylates" refers – in accordance with general understanding – to polymers that are accessible through radical polymerization of acrylic and / or methylacrylic monomers and optionally other copolymerizable monomers. According to the invention, the term "poly(meth)acrylate" encompasses polymers based on acrylic acid and its derivatives, as well as those based on acrylic and methacrylic acids and their derivatives, and those based on methacrylic acid and its derivatives, wherein the polymers always contain acrylic esters, methacrylic esters, or mixtures of acrylic and methacrylic esters.

[0018] Preferably, the monomers of the poly(meth)acrylates and their quantitative composition are chosen such that, according to the so-called Fox equation (G1 ) _ = y w n (G1 )

[0019] T ' G n TG,n

[0020] (cf. TG Fox, Bull. Am. Phys. Soc. 1 (1956) 123) yields a glass transition temperature TG for the polymer of < 25 °C. Such a value is particularly advantageous for pressure-sensitive adhesives that are used essentially at room temperature.

[0021] In equation G1, n represents the number of iterations over the monomers used, w n the mass fraction of the respective monomer n (wt%) and Tc,n the respective glass transition temperature of the homopolymer made from the respective monomers n in Kelvin.

[0022] Preferably, the one or more poly(meth)acrylate(s) can be traced back to the following monomer composition: a) Acrylic acid esters and / or methacrylic acid esters of the formula CH2=C(R I )(COOR 11 ), wherein R 1= H or CH3 and R" is an alkyl group with 1 to 30 C atoms, more preferably with 4 to 14 C atoms, particularly preferably with 4 to 9 C atoms; b) olefinically unsaturated monomers with functional groups exhibiting reactivity with crosslinking substances; c) optionally further olefinically unsaturated monomers that are copolymerizable with monomers (a) and (b).

[0023] Examples of monomers a) are methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, n-pentyl acrylate, n-hexyl acrylate, n-heptyl acrylate, n-octyl acrylate, n-octyl methacrylate, n-nonyl acrylate, lauryl acrylate, stearyl acrylate, behenyl acrylate and their branched isomers such as isobutyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, isooctyl acrylate, isooctyl methacrylate. Particularly preferably, R" represents a methyl, an n-butyl, and a 2-ethylhexyl group, especially an n-butyl and a 2-ethylhexyl group, or the monomers a) are selected from n-butyl acrylate and 2-ethylhexyl acrylate.

[0024] The monomers b) are preferably olefinically unsaturated monomers with functional groups that can react with epoxide groups. Particularly preferably, the monomers b) each contain at least one functional group selected from the group consisting of hydroxy, carboxy, sulfonic acid and phosphonic acid groups, acid anhydride functional groups, epoxide groups and substituted or unsubstituted amino groups.

[0025] In particular, the monomers b) are 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, 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, 6-hydroxyhexyl methacrylate, allyl alcohol, glycidyl acrylate, and glycidyl methacrylate. The monomers b) acrylic acid and / or methacrylic acid, especially acrylic acid, are particularly preferred.

[0026] In principle, all vinylically functionalized compounds that can be copolymerized with monomers a) and monomers b) are suitable as monomers c). The properties of the pressure-sensitive adhesive can be advantageously controlled by selecting and adjusting the quantity of monomers c).

[0027] The monomers c) are particularly preferably selected from the group consisting of benzyl acrylate, benzyl methacrylate, phenyl acrylate, phenyl methacrylate, tert-butyl phenyl acrylate, tert-butyl phenyl methacrylate, phenoxyethyl acrylate, 2-butoxyethyl methacrylate,

[0028] 2-Butoxyethyl acrylate, 4-cumyl-phenyl methacrylate, cyanoethyl acrylate, cyanoethyl methacrylate,

[0029] 4-biphenyl acrylate, 4-biphenyl methacrylate, 2-naphthyl acrylate, 2-naphthyl methacrylate, tetrahydrofurfuryl acrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate,

[0030] 3-Methoxyacrylic acid methyl ester, 3-methoxybutyl acrylate, phenoxyethyl acrylate, phenoxy-ethyl methacrylate, 2-phenoxyethyl methacrylate, butyl diglycol methacrylate, ethylene glycol acrylate, ethylene glycol monomethyl acrylate, methoxy polyethylene glycol methacrylate 350, methoxy polyethylene glycol methacrylate 500, propylene glycol monomethacrylate,

[0031] Butoxydiethylenglykolmethacrylat, Ethoxytriethylenglykolmethacrylat, Octafluoropentyl- acrylat, Octafluoropentylmethacrylat, 2,2,2-Trifluoroethylmethacrylat, 1 ,1 ,1 ,3,3,3-Hexa- fluoroisopropylacrylat, 1 ,1 ,1 ,3,3,3-Hexafluoroisopropylmethacrylat, 2,2,3,3,3-Pentafluoro- propylmethacrylat, 2,2,3,4,4,4-Hexafluorobutylmethacrylat, 2,2,3,3,4,4,4-Heptafluoro- butylacrylat, 2,2,3,3,4,4,4-Heptafluorobutylmethacrylat, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,8,8-

[0032] Pentadecafluorooctylmethacrylat, Dimethylaminopropylacrylamid, Dimethylaminopropylmethacrylamid, N-(1 -Methyl-undecyl)acrylamid, N-(n- Butoxymethyl)acrylamid, N-(Butoxymethyl)methacrylamid, N-(Ethoxymethyl)acrylamid, N-(n-Octadecyl)acrylamid,

[0033] N,N-Dialkyl-substituierten Amiden, insbesondere N,N-Dimethylacrylamid, N,N-Dimethylmethacrylamid, N-Benzylacrylamid, N-Isopropylacrylamid,

[0034] N-tert-butylacrylamide, N-tert-octylacrylamide, N-methylolacrylamide, N-methylolmethacrylamide; also acrylonitrile, methacrylonitrile; vinyl ethers such as vinyl methyl ether, ethyl vinyl ether, vinyl isobutyl ether; vinyl esters such as vinyl acetate; vinyl chloride, vinyl halides, vinylidene halides, vinylpyridine, 4-vinylpyridine, N-vinylphthalimide, N-vinyllactam, N-vinylpyrrolidone, styrene, o- and p-methylstyrene, o-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene, 3,4-dimethoxystyrene, 2-polystyrene ethyl methacrylate (molecular weight M w from 4,000 to 13,000 g / mol), poly(methyl methacrylate)ethyl methacrylate (M w from 2,000 to 8,000 g / mol), vinylcaprolactam, potassium acrylic acid (3-sulfopropyl) ester and ethylenediglycol acrylate.

[0035] The monomers c) can advantageously be chosen to contain functional groups that support radiation-chemical crosslinking (for example, by electron beams or UV light). Suitable copolymerizable photoinitiators are, for example, benzoin acrylate and acrylate-functionalized benzophenone derivatives. Monomers that support crosslinking by electron irradiation are, for example, tetrahydrofurfuryl acrylate, N-tert-butylacrylamide, and allyl acrylate.

[0036] In one embodiment, the poly(meth)acrylates according to the invention comprise up to 30 wt.% of one or more acrylamides, wherein the wt.% refers to the total weight of the poly(meth)acrylates.

[0037] In a further embodiment, the poly(meth)acrylates according to the invention comprise at least 50 wt.% of one or more acrylates and up to 30 wt.% of one or more acrylamides, wherein the wt.% refers to the total weight of the poly(meth)acrylates.

[0038] Particularly preferred are the one or more poly(meth)acrylates based on the monomer composition described above. In particular, the poly(meth)acrylates according to the invention are based on a monomer composition consisting of acrylic acid, n-butyl acrylate, and 2-ethylhexyl acrylate.

[0039] Poly(meth)acrylate is particularly preferred, or rather, all poly(meth)acrylates are based on the following monomer composition: Acrylic acid 1 - 15 wt%

[0040] 2-Ethylhexyl acrylate 30 - 85 wt.%, n-Butyl acrylate and / or Methyl acrylate 10 - 67 wt.%, the proportions of the monomers adding up to 100 wt.%.

[0041] In an alternative embodiment, the poly(meth)acrylate, or rather all poly(meth)acrylates, can be traced back to the following monomer composition:

[0042] Acrylic acid 20 - 90 wt.%

[0043] 2-Ethylhexyl acrylate and / or n-butyl acrylate 10 - 80 wt.%,

[0044] Further olefinically unsaturated monomers 0 - 10 wt.%, the proportions of the monomers adding up to 100 wt.%.

[0045] The substance polymerization according to the invention is carried out using a first polymerization regulator and a second polymerization regulator, i.e. using two structurally different polymerization regulators.

[0046] Polymerization regulators (also called regulators or chain transfer agents) are generally compounds with high transfer constants. Polymerization regulators accelerate chain transfer reactions, thereby reducing the degree of polymerization of the resulting polymers without affecting the overall reaction rate. Polymerization regulators are materials that regulate radical polymerization and are well-known in the field. Regulators can be classified as mono-, bi-, or polyfunctional, depending on the number of functional groups in the molecule that can lead to one or more chain transfer reactions. Suitable regulators, their transfer constants, and their consumption during polymerization are described in detail by K.C. Berger and G. Brandrup in J. Brandrup, E.H. Immergut, Polymer Handbook, 4th ed., John Wiley & Sons, New York, 1998, pp. II / 97–11 / 180.Suitable chain transfer agents include halogenated hydrocarbons such as carbon tetrabromide; sulfur compounds such as lauryl mercaptan, butyl mercaptan, ethanethiol, isooctyl thioglycolate (IOTG), 2-ethylhexyl thioglycolate.

[0047] 2-Ethylhexyl mercaptopropionate, 2-mercaptoimidazole and 2-mercaptocthyl ether; and solvents such as ethanol, isopropanol and ethyl acetate, with ethyl acetate being considered an extremely weak regulator.

[0048] In a preferred embodiment, the chain transfer agents used have a higher transfer constant than ethyl acetate, preferably a transfer constant that is at least 10 times, alternatively 20 times, or alternatively 30 times higher. This is particularly advantageous because the use of extremely weak regulators leads to high VOCs after the substance polymerization and / or high amounts of solvents used during the polymerization.

[0049] The amount of chain transfer agent that is useful depends on the desired molecular weight and the type of chain transfer agent. Solvents are useful as chain transfer agents, but they are generally not as active as, for example, sulfur compounds.

[0050] In accordance with expert understanding, the use of solvent as a polymerization regulator is not inconsistent with essentially solvent-free polymerization, since the monomer composition to be reacted or the polymers formed are not dissolved at the amounts of polymerization regulator typically used.

[0051] Suitable regulators include aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, n-butylaldehyde, and isobutylaldehyde.

[0052] Furthermore, the following can also be used as regulators: formic acid, its salts or esters, such as ammonium formate, 2,5-diphenyl-1-hexene, hydroxylammonium sulfate, and hydroxylammonium phosphate.

[0053] Other suitable regulators are halogen compounds, e.g. alkyl halides such as tetrachloromethane, chloroform, bromotrichloromethane, bromoform, allyl bromide, and benzyl compounds such as benzyl chloride or benzyl bromide.

[0054] Other suitable regulators are allyl compounds, such as allyl alcohol, functionalized allyl ethers, such as allyl ethoxylates, alkyl allyl ethers, or glycerol monoallyl ethers.

[0055] Other suitable regulators are adhesive-enhancing resins that contain appropriate functional groups, such as hydroxyl, carboxyl, or ester groups, e.g., rosin resins and polyterpene-based resins. The number of hydroxyl groups in such resins is typically specified in commercially available products by the so-called hydroxyl number, which represents a measure of their functional reactivity.

[0056] In a preferred embodiment, connections containing an -SH group are used as regulators.

[0057] The -SH group-containing compound is preferably selected from alkyl thiols and hydroxycarboxylic acids. For example, the -SH group-containing compound is dodecanethiol (lauryl mercaptan), 2-mercaptopropionic acid, or thioglycolic acid (mercaptoacetic acid). Preferably, the -SH group-containing compound contains neither a carboxy group nor a thiocarboxy group. A -SH group-containing compound, especially dodecanethiol, is therefore particularly preferred. One or more -SH group-containing compounds may be included in the composition of the pressure-sensitive adhesive; preferably, a single -SH group-containing compound is included.

[0058] In one embodiment, compounds containing sulfur in bound form are used as regulators.

[0059] Examples of compounds of this type include inorganic hydrogen sulfites, disulfites, and dithionites, or organic sulfides, disulfides, polysulfides, sulfoxides, and sulfones. These include di-n-butyl sulfide, di-n-octyl sulfide, diphenyl sulfide, thiodiglycol, ethylthioethanol, diisopropyl disulfide, di-n-butyl disulfide, di-n-hexyl disulfide, diacetyl disulfide, diethanol sulfide, di-t-butyl trisulfide, dimethyl sulfoxide, dialkyl sulfide, dialkyl disulfide, and / or diarylsulfide.

[0060] Compounds preferably used as polymerization regulators are thiols (compounds containing sulfur in the form of SH groups, also known as mercaptans). Mono-, bi-, and polyfunctional mercaptans, mercapto alcohols, and / or mercaptocarboxylic acids are preferred as regulators.

[0061] Examples of these compounds are allyl thioglycolates, ethyl thioglycolate, cysteine, 2-mercaptoethanol, 1,3-mercaptopropanol, 3-mercaptopropane-1,2-diol, 1,4-mercaptobutanol, mercaptoacetic acid, 3-mercaptopropionic acid, mercaptosuccinic acid, thioglycerol, thioacetic acid, thiourea and alkyl mercaptans such as n-butyl mercaptan, n-hexyl mercaptan or n-dodecyl mercaptan.

[0062] Particularly favored thiols are cysteine, 2-mercaptoethanol, 1,3-mercaptopropanol, 3-mercaptopropane-1,2-diol, thioglycerol, thiourea.

[0063] Examples of bifunctional regulators containing two sulfur compounds in bonded form are bifunctional thiols such as dimercaptopropanesulfonic acid (sodium salt), dimercaptobemmic acid, dimercapto-1-propanol, dimercaptoethane, dimercaptopropane, dimercaptobutane, dimercaptopentane, dimercaptohexane, ethylene glycol bisthioglycolates and butanediol bisthioglycolate.

[0064] Examples of polyfunctional regulators are compounds containing more than two sulfur atoms in bound form. Trifunctional and / or tetrafunctional mercaptans are examples of these.

[0065] Preferred trifunctional regulators are trifunctional mercaptans, such as trimethylolpropane tris(2-mercaptoethanate, trimethylolpropane tris(3-mercaptopropionate), trimethylolpropane tris(4-mercaptobutanate), trimethylolpropane tris(5-mercaptopentanate), trimethylolpropane tris(6-mercaptohexanate), Trimethylolpropane-tris(2-mercaptoacetate), glycerylthioglycolate, glycerylthiopropionate, glycerylthioethylate, glycerylthiobutanate, 1,1,1-propanetriyl-tris-(mercaptoacetate), 1,1,1-propanetriyl-tris-(mercaptoethanate), 1,1,1 -Propanetriyl-tris- (mercaptoproprionate), 1,1,1 -Propanetriyl-tris-(mercaptobutanate), 2-hydroxymethyl-2-methyl-

[0066] 1,3-propanediol-tris-(mercaptoacetate), 2-hydroxmethyl-2-methyl-1,3-propanediol-tris-

[0067] (mercaptoethanate), 2-hydroxmethyl-2-methyl-1,3-propanediol tris-(mercaptopropionate), 2-hydroxmethyl-2-methyl-1,3-propanediol tris-(mercaptobutanate).

[0068] Particularly preferred trifunctional regulators are glyceryl thioglycolate, trimethylolpropane tris(2-mercaptoacetate), 2-hydroxymethyl-2-methyl-1,3-propanediol tris-(mercaptoacetate).

[0069] Preferred tetrafunctional mercaptans are pentaerythritol tetrakis-(2-mercaptoacetate),

[0070] Pentaerythritol tetrakis-(2-mercaptoethanate), Pentaerythritol tetrakis(3-mercaptopropionate),

[0071] Pentaerythritol tetrakis-(4-mercaptobutanate), Pentaerythritol tetrakis(5-mercaptopentanate),

[0072] Pentaerythritol tetrakis (6-mercaptohexanate).

[0073] Further Si compounds as polyfunctional controllers are described, for example, in EP 2 066 705 B1.

[0074] In a preferred embodiment, the first polymerization regulator is substantially consumed during polymerization, while the second polymerization regulator is present after polymerization in at least 70% of the amount used.

[0075] In this context, "essentially consumed" means that the first polymerization regulator is a particularly active polymerization regulator and is therefore consumed during the polymerization reaction (see also K.C. Berger and G. Brandrup in J. Brandrup, E.H. Immergut, Polymer Handbook, 4th ed., John Wiley & Sons, New York, 1998, pp. II / 97 - 11 / 180). In the present application, "essentially consumed" means that after the polymerization reaction, the first polymerization regulator is present in its originally used form in a proportion of less than 10%, preferably less than 5%, particularly preferably less than 2%, and even more preferably less than 1%. The second polymerization regulator is still present after polymerization in its originally used form in a proportion of at least 60%, or alternatively at least 70%, of the amount used, which is why it can be classified as a "less active polymerization regulator".

[0076] In this context, “after polymerization” means that the polymerization has resulted in a monomer conversion of more than 95%, preferably more than 98%, and particularly preferably more than 99% of the monomers to be polymerized.

[0077] The monomer conversion and the residual content of the first polymerization regulator CTA-1 and the second polymerization regulator CTA-2 after polymerization are determined, for example, by gas chromatography with mass-selective detection (GC-MSD) according to DIN EN ISO / IEC 17025. In GC-MSD, calibration is performed using a mass-selective detector, and the samples are injected undiluted.

[0078] In a preferred embodiment, the transfer constants of the first polymerization regulator k satisfy CTA1 and the transfer constants of the second polymerization regulator k CTA2 the condition k CTA1 > 100 k CTA2The transfer constant of the first polymerization regulator is greater than or equal to one hundred times the transfer constant of the second polymerization regulator. Therefore, the first polymerization regulator is a more active polymerization regulator than the second polymerization regulator. The aforementioned transfer constants (k CTA1 and k CTA2 The transfer constants depend on the polymerization and the polymerization conditions chosen. The determination of the transfer constant is known in the literature; see, for example, K.C. Berger and G. Brandrup in J. Brandrup, E.H. Immergut, Polymer Handbook, 4th ed., John Wiley & Sons, New York, 1998, pp. II / 97–11 / 180. Furthermore, literature values ​​are known for various polymerization regulators and monomers to be polymerized. In the present application, the transfer constants of the first polymerization regulator k satisfy CTA1 and the transfer constants of the second polymerization regulator kCTA2 The condition k is preferred CTA1 > 100 k CTA2 , especially preferred k CTA1 > 1,000 k CTA2 , where the transfer constants of the polymerization regulators for the polymerization of methyl methacrylate at 60°C are determined.

[0079] In a preferred embodiment, the first polymerization regulator is a compound containing an -SH group, preferably selected from alkyl thiols and hydroxycarboxylic acids. For example, the -SH group-containing compound is dodecanethiol (lauryl mercaptan), 2-mercaptopropionic acid, or thioglycolic acid (mercaptoacetic acid). Preferably, the -SH group-containing compound contains neither a carboxy group nor a thiocarboxy group. Therefore, dodecanethiol is particularly preferred. One or more -SH group-containing compounds may be included in the composition of the preferred (meth)acrylate oligomer; preferably, a single -SH group-containing compound is included.

[0080] In a preferred embodiment, the second polymerization regulator is a compound containing an -OH group, preferably an alcohol, and more preferably a secondary alcohol. For example, the compound containing one -OH group is isopropanol. Preferably, the compound containing one -OH group does not contain a carboxy group or a thiocarboxy group.

[0081] In a preferred embodiment, the second polymerization regulator is an alkanol.

[0082] In a particularly preferred embodiment, the first polymerization regulator is a thioalcohol and the second polymerization regulator is an alcohol, in particular a secondary alcohol.

[0083] The polymerization regulators are typically used in total amounts of all polymerization regulators of about 0.001 parts to about 10 parts by weight per 100 parts of the total amount of monomers to be polymerized, preferably the polymerization regulators are used in total amounts of about 0.01 parts to about 0.5 parts and most preferably from about 0.02 parts to about 0.20 parts.

[0084] In a preferred embodiment, 0.01 to 0.03 wt.% of the first polymerization regulator and 0.5 to 1.5 wt.% of the second polymerization regulator are used in the polymerization, wherein the wt.% values ​​refer to 100 wt.% of monomers to be polymerized.

[0085] Weight-average molecular weight

[0086] The weight-average molecular weight M wThe poly(meth)acrylate content is preferably 500,000 to 3,000,000 g / mol; very preferably 700,000 to 2,800,000 g / mol, most preferably 900,000 to 2,200,000 g / mol (determined by gel permeation chromatography, see experimental section).

[0087] In a preferred embodiment, the poly(meth)acrylate has an average molecular weight of more than 500,000 g / mol, preferably more than 700,000 g / mol, in particular more than 900,000 g / mol or even more preferably more than 1,000,000 g / mol (determined by gel permeation chromatography, see experimental part).

[0088] Loam content

[0089] In this application, a poly(meth)acrylate with a low gel content is defined as having a gel content of less than 5 wt.%, preferably less than 2 wt.%, and particularly preferably less than 1 wt.%, where the wt.% refers to 100 parts by weight of the poly(meth)acrylate. The determination of the gel content is described in the section on measurement and testing methods.

[0090] In a preferred embodiment, the one or more poly(meth)acrylates according to the invention have a gel content of less than 2 wt.% and an average molecular weight of more than 500,000 g / mol.

[0091] In a particularly preferred embodiment, the one or more poly(meth)acrylates according to the invention have a gel content of less than 1 wt.% and an average molecular weight of more than 700,000 g / mol, more preferably 900,000 g / mol, or even 1,000,000 g / mol.

[0092] The person skilled in the art is familiar with various manufacturing processes of poly(meth)acrylates, in particular by conventional radical polymerizations or controlled radical polymerizations.

[0093] The poly(meth)acrylates according to the invention are produced by bulk polymerization, i.e., a polymerization in which, after polymerization, less than 5.0 wt%, preferably less than 3.0 wt%, particularly preferably less than 2.0 wt%, and most preferably less than or equal to 1.5 wt% of volatile organic compounds (VOCs) are present. This differs from alternative conventional methods of radical polymerization, including solution polymerization, dispersion polymerization, emulsion polymerization, and suspension polymerization. The reaction product of the polymerizable materials can be random or block copolymers.

[0094] The weight fraction of volatile organic compounds (VOCs) is determined according to the measurement method in the section “Measurement and Testing Methods”.

[0095] During bulk polymerization, the polymers forming can exist in the composition of the monomers being polymerized. According to established technical understanding, this differs from solvent polymerization, where, particularly after polymerization, solvents or polymers are typically still present dissolved in solvents. Similarly, the use of a solvent as a polymerization regulator, according to established technical understanding, is not the same as the use of a solvent, dispersant, or diluent.

[0096] In a preferred embodiment, the poly(meth)acrylates according to the invention are produced by a substance polymerization with little solvent, essentially solvent-free or with no solvent.

[0097] The poly(meth)acrylates can be produced by copolymerization of the monomeric components using the usual polymerization initiators and polymerization regulators, with the polymerization taking place in bulk at the usual temperatures.

[0098] In the present application, “low solvent” means that less than 5 wt% solvent, based on the total mass of reaction substrate used, is used in the (mass) polymerization.

[0099] In the present application, “essentially solvent-free” means that less than 2 wt.%, preferably less than or equal to (<) 1 wt.%, or even no solvent at all, is used in the (mass) polymerization, based on the total mass of reaction substrate used.

[0100] In this document, the term "reaction template" refers to the starting materials presented for polymerization. Depending on the situation, these can be a monomer (for the production of homopolymers) or a monomer mixture (for the production of copolymers). Furthermore, additional additives (such as initiators, regulators, and the like) may be present for polymerization. In the case of solvent polymerization or dispersion polymerization, the solvent(s) or dispersant(s) may also be present.

[0101] When this text refers to "a chemical compound" or "a chemical substance"—such as a monomer, a regulator, a regulator substance, an initiator, or the like—it does not mean the individual molecule, but rather the type of chemical compound or substance, i.e., the respective group of identical molecules. When referring to the individual molecule, it speaks of the molecule of the corresponding chemical substance (i.e., a monomer molecule, a regulator molecule, a regulator substance molecule, or an initiator molecule).Accordingly, the expression "multiple chemical compounds" (for example, also multiple monomers, multiple regulators, and so on) means multiple groups of identical molecules (for example, "multiple monomers" means multiple groups of identical monomer molecules in the respective group, with the monomer molecules differing between the respective groups; "multiple regulators" means multiple groups of identical regulator molecules in the respective group, with the regulator molecules differing between the respective groups; etc.).

[0102] Photoinitiator

[0103] In one embodiment, at least one photoinitiator is used in the substance polymerization.

[0104] In principle, all commonly known 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 benzpinacol. 2,2'-Azobis(2-methylbutyronitrile) or 2,2'-Azobis(2-methylpropionitrile) (2,2'-Azobisisobutyronitrile; AIBN) is particularly preferred as a radical initiator.

[0105] An initiator for radical polymerization is typically added to the various monomers used to form the poly(meth)acrylates according to the invention. The polymerization initiator can be a thermal initiator, a photoinitiator, or both. Any suitable thermal initiator or photoinitiator known for radical polymerization reactions can be used. The initiator is typically present in an amount in the range of 0.01 to 5 wt%, 0.01 to 2 wt%, 0.01 to 1 wt%, or 0.01 to 0.5 wt% based on the total weight of the (co)polymerizable material. In principle, all conventional initiators familiar to those skilled in the art are suitable. Examples of radical sources are peroxides, hydroperoxides, and azo compounds, e.g.Dibenzoyl peroxide, cumene hydroperoxide, cyclohexanone peroxide, di-tert-butyl peroxide, cyclohexylsulfonyl acetyl peroxide, diisopropyl percarbonate, tert-butyl peroctoate, benzopinacol. In a highly preferred process, 2,2'-azobis(2-methylbutyronitrile) (Vazo® 67™ from DuPont) or 2,2'-azobis-(2-methylpropionitrile) (2,2'-azobisisobutyronitrile; AIBN; Vazo® 64™ from DuPont) is used as the radical initiator. In some aspects, a thermal initiator is used. Thermal initiators can be water-soluble or water-insoluble (i.e., oil-soluble), depending on the polymerization process used. Suitable water-soluble initiators include, but are not limited to, persulfates such as potassium peroxide, ammonium persulfate, sodium persulfate, and mixtures thereof; an oxidation-reduction initiator such as the reaction product of a persulfate and a reducing agent such as a metabisulfite (e.g. sodium metabisulfite) or a bisulfate (e.g.Sodium bisulfate); or 4,4'-azobis(4-cyanopentanic acid) and its soluble salts (e.g., sodium, potassium). Suitable oil-soluble initiators include, but are not limited to, various azo compounds such as those available under the trade name VAZO from E.L. DuPont de Nemours Co., including VAZO 67, which is 2,2'-azobis(2-methylbutynitrile), VAZO 64, which is 2,2'-azobis(isobutyronitrile), and VAZO 52, which is 2,2'-azobis(2,4-dimethylpentannitrile); and various peroxides such as benzoyl peroxide, cyclohexanone peroxide, lauroyl peroxide, and mixtures thereof.

[0106] In some other aspects, a photoinitiator is used. Some example photoinitiators are benzoin ethers (e.g., benzoin methyl ether or benzoin isopropyl ether) or substituted benzoin ethers (e.g., anisoin methyl ether). Other example photoinitiators are substituted acetophenones such as 2,2-diethoxyacetophenone or 2,2-dimethoxy-2-phenylacetophenone (commercially available under the trade name IRGACURE 651 from BASF Corp. (Florham Park, NJ) or under the trade name ESACURE KB-1 from Sartomer (Exton, PA)). Further example photoinitiators are substituted alpha-ketols such as 2-methyl-2-hydroxypropiophenone, aromatic sulfonyl chlorides such as 2-naphthalenesulfonyl chloride, and photoactive oxime compounds such as 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)oxime.Other suitable photoinitiators include, for example, 1-hydroxycyclohexylphenyl ketone (IRGACURE 184), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (IRGACURE 819), 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one (IRGACURE 2959), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone (IRGACURE 369), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (IRGACURE 907) and 2-hydroxy-2-methyl-1-phenylpropan-1-one (DAROCUR 1 173).

[0107] Syrup polymerization, polymerization in a reactor, and polymerization in a closed shell

[0108] The polymerization can, in principle, be carried out in any manner. Preferably, it takes place in a reactor, particularly in a reactor designed for processing highly viscous masses, as syrup polymerization or in a closed shell. In a preferred embodiment, the poly(meth)acrylate according to the invention is produced by a substance polymerization selected from i. syrup polymerization; ii. polymerization in a reactor; or iii. polymerization in a closed shell, preferably in a bag, particularly preferably in a thermoplastic bag.

[0109] Syrup polymerization

[0110] In one embodiment, the poly(meth)acrylate is produced by syrup polymerization. The monomer mixtures used for polymerization typically have a viscosity that is too low at the beginning of the polymerization process to be easily handled. To increase the viscosity, the monomer mixture is prepolymerized to a syrupy consistency; this can advantageously be done up to a conversion of 2–20%. This results in a syrup that can be readily coated onto a support material. UV light with a wavelength of 280–450 nm is preferably used to initiate the prepolymerization.

[0111] Furthermore, the monomers are optionally mixed with resins after or preferably before prepolymerization. Before complete polymerization, additional monomers can be added to or mixed into the syrup.

[0112] After coating in syrup form, the second stage of polymerization takes place in the already coated form under anaerobic conditions until the desired reaction is achieved on the syrup-coated web by further irradiation with UV light. The result of this second stage of the polymerization reaction on the web is determined by parameters known to those skilled in the art, such as web speed, number of lamps, UV wavelength, light intensity, and cooling power.

[0113] The inventive method is particularly advantageous for the production of, for example, adhesive tapes, since the prepolymer can be coated onto a substrate as a syrup.

[0114] Polymerization in a reactor

[0115] For substance polymerization in a reactor, various polymerization reactors are known to those skilled in the art, such as kneading reactors. Alternative polymerization reactors include stirred tank reactors, tubular reactors, and batch reactors.

[0116] In a polymerization reactor for bulk polymerization, the liquid monomers are typically introduced into the reactor first. An initiator is then added to start the polymerization. The reaction is carried out under controlled conditions, with temperature and pressure regulated to achieve the desired reaction rate and polymer structure. For highly viscous reactions, as are common in bulk polymerization, intensive mixing is required to ensure a uniform distribution of the reactants. Since polymerization is exothermic, the heat generated must be efficiently dissipated to prevent overheating and product degradation. During polymerization, the monomers combine to form polymer chains, with the viscosity of the mixture continuously increasing.Once the desired polymerization stage is reached, the reaction is stopped, for example by adding an inhibitor or by cooling.

[0117] Polymerization in a closed shell

[0118] In one embodiment, the poly(meth)acrylate is produced by polymerization in a closed shell. In this embodiment, the polymerization thus takes place within a closed shell. A closed shell is understood to be any system, of any design, which does not impede the polymerization process, spatially confines and completely surrounds the composition to be polymerized or undergoing polymerization, and at least partially, preferably prevents, the passage of air, water, and the enclosed monomers.

[0119] The material of the closed shell is preferably selected from the group consisting of ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, polyethylene, polypropylene, polybutadiene, ionomer films, and mixtures thereof; more preferably, it is selected from polyethylene, ethylene-vinyl acetate copolymers, and mixtures thereof. The thickness of the closed shell material is preferably 30 to 100 µm, more preferably 35 to 70 µm, and particularly 40 to 60 µm. The thickness of a closed shell filled with the materials to be polymerized is preferably 2 to 22 mm, more preferably 5 to 21 mm, and particularly 7 to 20 mm.

[0120] In a preferred embodiment, the closed casing is a bag, in particular a thermoplastic bag. The closed casing is produced, for example, by layering two film sheets on top of each other and heat-sealing them along the long sides and the bottom edge. The monomer mixture to be polymerized is then filled into the casing using a liquid forming, filling, and sealing machine. Subsequently, the casing is sealed section by section through the liquid surface, resulting in several filled, closed casings that are then separated from one another.

[0121] For the polymerization of poly(meth)acrylates in a closed shell, a monomer mixture to be polymerized is (completely) surrounded by the packaging material to form a packaged pressure-sensitive adhesive composition. In accordance with the process of the present disclosure, the packaging material used is meltable and miscible with one or more poly(meth)acrylates.

[0122] In an advantageous embodiment, the closed casing is in the form of a bag, in particular a thermoplastic bag. Typically, the packaging material comprises a base material, which is in particular a polymer base material, preferably with a melting point of at most 200°C, at most 180°C, or even at most 160°C. Even more preferably, the packaging material comprises a base material, in particular a polymer base material, with a melting point in the range of 90°C to 150°C.

[0123] According to an advantageous aspect of the present disclosure, the packaging material used herein comprises a base material, in particular a thermoplastic polymer base material, typically selected from the group consisting of ethylene vinyl acetate, ethylene acrylic acid, polypropylene, polyethylene, polybutadiene, ionic films, and combinations or mixtures thereof. Advantageously, the packaging material used herein comprises a thermoplastic polymer base material selected from the group consisting of ethylene vinyl acetate, ethylene acrylic acid, and combinations or mixtures thereof. Suitable packaged hot-melt processable adhesive compositions and the packaging material used herein are disclosed, for example, in U.S. Patent Nos. 5,804,610 (Hamer et al.), U.S. A1-2005 / 0022476 (Hamer et al.), and LIS A1-2013 / 0184394 (Satrijo et al.), the full contents of which are hereby incorporated by reference. Batch process

[0124] According to one advantageous aspect, one or more poly(meth)acrylates are produced in a batch process.

[0125] A batch process, also known as batch production, batch operation, or batch operation, is a discontinuous production method used particularly for the synthesis of chemicals. In the chemical industry, batch production refers to a process in which the product is passed through one or more reactors and remains there until the reaction is complete and the next production step can begin.

[0126] A typical batch process sequence includes the following steps: a) Complete filling of the reaction vessel with the starting materials (reactants); b) Reaction of the reactants, whereby their concentration continuously decreases while the concentration of the products continuously increases; c) Transfer of the products to the downstream process;

[0127] Batch processes, particularly in the production of poly(meth)acrylates, offer the advantage that no additional components need to be added during the process, thus simplifying the process control. Furthermore, the reaction vessel can be cleaned before each run, preventing deposits that can accumulate in a continuous process. This is especially advantageous for the production of essentially gel-free poly(meth)acrylates.

[0128] A special embodiment of the batch process is polymerization in a closed shell. In this embodiment, the closed shell represents the reaction vessel, which can be further processed with the formed poly(meth)acrylate or separated from it in subsequent process steps.

[0129] Adhesive

[0130] Another aspect of the invention is an adhesive compound comprising one or more poly(meth)acrylates according to the invention.

[0131] In one embodiment, the poly(meth)acrylate pressure-sensitive adhesive according to the invention is a pressure-sensitive adhesive based on poly(meth)acrylates. "Based on" or "on the basis of" or "based on" means in this context that the properties of the pressure-sensitive adhesive are at least strongly determined by the fundamental properties of the poly(meth)acrylate, although it is naturally not excluded that these properties may be further influenced by the use of modifying auxiliaries or additives in a composition. In particular, this may mean that the proportion of poly(meth)acrylate in the total mass of the pressure-sensitive adhesive is more than 50% by weight.

[0132] In one embodiment, the adhesive compound according to the invention comprises at least one poly(meth)acrylate at least 50 wt.%, preferably at least 60 wt.%, particularly preferably at 70 wt.% based on the total weight of the adhesive compound.

[0133] In accordance with professional understanding, an adhesive is an adhesive that possesses pressure-sensitive properties, meaning it forms a permanent bond to a substrate even under relatively light pressure. Such adhesives or pressure-sensitive tapes are generally permanently tacky even at room temperature, meaning they exhibit a certain viscosity and tackiness, allowing them to wet the surface of a substrate even with minimal pressure. While not bound to this theory, it is often assumed that an adhesive can be considered an extremely highly viscous liquid with an elastic component, which consequently exhibits characteristic viscoelastic properties that lead to the permanent tackiness and pressure-sensitive adhesion described above.It is assumed that pressure-sensitive adhesives undergo both viscous flow processes and the development of elastic restoring forces during mechanical deformation. The viscous flow contributes to adhesion, while the elastic restoring forces are particularly necessary for cohesion. The relationships between rheology and pressure sensitivity are well-established in the art and are described, for example, in "Satas, Handbook of Pressure Sensitive Adhesives Technology," Third Edition, (1999), pages 153 to 203. The storage modulus (G') and the loss modulus (G") are typically used to characterize the degree of elastic and viscous components. These can be determined by dynamic mechanical analysis (DMA), for example, using a rheometer.Within the scope of the present invention, an adhesive compound is preferably understood to be adhesive and thus a pressure-sensitive adhesive compound if, at a temperature of 23 °C in the deformation frequency range of 10° to 10. 1 rad / sec G' and G" each at least partially in the range of 10 3 up to 10 7 Pa lie.

[0134] During the processing of poly(meth)acrylates into an adhesive, particularly a pressure-sensitive adhesive, the polymer system can be mixed with other components. These other components can be selected from the group consisting of other polymers; crosslinkers; adhesive-enhancing resins; fillers, for example, electrically conductive fillers, thermally conductive fillers, and the like; flame retardants, for example, ammonium polyphosphate and its derivatives; foaming agents; antioxidants; light stabilizers; plasticizers; and compounding particles.

[0135] Networker

[0136] Preferably, the poly(meth)acrylates are crosslinked in the adhesive compound according to the invention. The poly(meth)acrylates according to the invention can be crosslinked chemically, by UV radiation, or by electron beam radiation.

[0137] In a preferred embodiment, the crosslinking is carried out using at least one covalent crosslinker and / or using a coordinative crosslinker.

[0138] Preferred covalent crosslinkers are epoxycyclohexyl derivatives and N,N-diglycidylamines. Preferred coordinative crosslinkers are chelate compounds, particularly multivalent metal chelates. Thermal crosslinking results in homogeneous crosslinking throughout the entire layer, whereas, for example, radiation-crosslinked compounds exhibit a crosslinking profile with decreasing crosslink density towards the interior of the compound. A homogeneously crosslinked adhesive layer enables the uniform distribution of stresses that can occur when the bond is subjected to load. Adhesive and cohesive properties can be very precisely balanced across the entire layer, allowing for the creation of durable bonds with a predictable property profile.

[0139] Particularly preferred thermal crosslinkers are N,N,N',N'-tetrakis(2,3-epoxypropyl)cyclohexane-1,3-dimethylamine (e.g. Syna Epoxy S610, Synasia) and N,N,N',N'-tetrakis(2,3-epoxypropyl)-m-xylene-a,a'-diamine (e.g. Erisys GA-240, CVC) as well as epoxycyclohexyl carboxylates, in particular (3,4-epoxycyclohexane)methyl-3,4-epoxycyclohexyl carboxylate and bis(3,4-epoxycyclohexylmethyl)adipate.

[0140] Preferred coordinative crosslinkers are multivalent metal chelates. "Multivalent metal chelates" are defined as compounds in which a multivalent metal is coordinatively bonded to one or more organic compounds. Preferred multivalent metal atoms include Al(III), Zr(IV), Co(II), Cu(I), Cu(II), Fe(II), Fe(IIII), Ni(II), V(II), V(IIII), V(IV), V(V), Zn(II), In(IIII), Ca(II), Mg(II), Mn(II), Y(IIII), Ce(II), Ce(IV), St(II), Ba(II), Mo(II), Mo(IV), Mo(VI), La(IIII), Sn(II), Sn(IV), and Ti(IV), in particular Al(IIII), Zr(IV), and Ti(IV).

[0141] In principle, all known ligands can serve as ligands for coordinative crosslinkers. However, the atoms used for the coordinative bonding of the organic compound are preferably those possessing free electron pairs, such as oxygen atoms, sulfur atoms, nitrogen atoms, and the like. Preferred organic compounds include alkyl esters, alcohols, carboxylic acids, ethers, and ketones. Particularly preferred coordinative crosslinkers are titanium dipropoxide bis(acetylacetonate), titanium dibutoxide bis(octylene glycholate), titanium dipropoxide bis(ethylacetoacetate), titanium dipropoxide bis(lactate), titanium dipropoxide bis(triethanolaminate), titanium di-n-butoxide bis(triethanolaminate), titanium tri-n-butoxide monostearate, and butyl titanate dimer.

[0142] poly(titanium acetylacetonate); Aluminum diisopropoxide monoethyl acetate, aluminum di-n-butoxide monomethyl acetoacetate, aluminum di-i-butoxide monomethyl acetoacetate, aluminum di-n-butoxide monoethyl acetoacetate, aluminum disec-butoxide monoethyl acetoacetate,

[0143] aluminum triacetylacetonate, aluminum triacetylacetonate,

[0144] Aluminium monoacetylacetonate bis(ethylacetoacetonate) and zirconium tetraacetylacetonate; in particular aluminium triacetylacetonate and aluminium diisopropoxide monoethyl acetate.

[0145] One or more covalent and one or more coordinative networkers can be used; each can also be used in combination with each other.

[0146] Crosslinking accelerators can be used; however, preferably the adhesive layer contains neither externally added nor polymerized accelerators, and in particular, it contains no accelerators at all.

[0147] Adhesive-enhancing resins

[0148] The term "adhesive-enhancing resin," synonymous with "adhesive resin" as defined in the present disclosure, is understood, according to the general understanding of those skilled in the art, to be an oligomeric or polymeric resin that increases the self-adhesion (tack, inherent stickiness) of the pressure-sensitive adhesive compared to an otherwise identical pressure-sensitive adhesive without an adhesive-enhancing resin. Furthermore, adhesive-enhancing resins can advantageously also improve the wetting properties of the pressure-sensitive adhesive with respect to the substrate to be bonded, its flow behavior, and / or its adhesion. The pressure-sensitive adhesive according to the invention can also comprise at least one adhesive-enhancing resin. According to the general understanding of those skilled in the art, this is understood to be an oligomeric or polymeric resin that increases the self-adhesion (tack, inherent stickiness) of the pressure-sensitive adhesive compared to an otherwise identical pressure-sensitive adhesive without an adhesive-enhancing resin.Furthermore, resins that enhance adhesive strength can also advantageously improve the wetting properties of the adhesive compound towards the substrate to be bonded, its release behavior and / or its adhesion.

[0149] The one or more adhesive-enhancing resins can, in principle, be any adhesive resin compatible with the pressure-sensitive adhesive and, in particular, with copolymer A or copolymers A of the pressure-sensitive adhesive.

[0150] The at least one adhesive-strengthening resin of the pressure-sensitive adhesive according to the invention can, in principle, be any adhesive resin compatible with the pressure-sensitive adhesive and, in particular, with the copolymer(s) of the pressure-sensitive adhesive. In one embodiment, the adhesive-strengthening resin is selected from the group consisting of aliphatic, aromatic, and alkylaromatic hydrocarbon resins; hydrocarbon resins based on pure monomers; hydrogenated hydrocarbon resins; and functional resins.

[0151] Hydrocarbon resins and optionally derivatized natural resins; preferably, the adhesive resin is selected from the group consisting of pinene, indene, and rosin resins, their disproportionated, hydrogenated, polymerized, esterified derivatives and salts; aliphatic and aromatic hydrocarbon resins; terpene resins and terpenephenolic resins, as well as C5, C9, and other hydrocarbon resins. The pressure-sensitive adhesive composition according to the invention can, in principle, comprise one (single) or several adhesive-strength-enhancing resins.

[0152] Particularly preferred is at least one adhesive-strengthening resin selected from rosin resins and polyterpene-based resins.

[0153] Rosin resins are understood to be a group of resins containing their disproportionate, hydrogenated, polymerized, modified derivatives, and salts.

[0154] Modified derivatives of rosin resin include esterified derivatives and / or further substituted derivatives such as maleate resin (CAS: 68038-41-5).

[0155] Rosin resins are advantageous because they can be largely, and in particular entirely, produced or obtained from renewable raw materials. These adhesive resins can be produced from renewable raw materials and have proven particularly suitable for significantly improving the adhesive properties of the pressure-sensitive adhesive compound according to the invention.

[0156] A fully hydrogenated rosin resin is particularly preferred as the adhesive-enhancing resin. This is especially advantageous because these resins have a comparatively low softening temperature and thus contribute favorably to the development of adhesive properties. Furthermore, they exhibit particularly good aging stability.

[0157] Preferably, the adhesive compound according to the invention comprises one or more adhesive-enhancing resins in a total of 5 to 50 wt.%, more preferably in a total of 7 to 45 wt.%, in particular in a total of 9 to 35 wt.%, and most preferably in a total of 10 to 32 wt.%, in each case based on the total weight of the adhesive compound.

[0158] The adhesive compound according to the invention can further comprise additional components, e.g. plasticizers; fillers, in particular fibers, carbon black, zinc oxide, titanium dioxide, spinels, dyes, pigments, chalk, solid or hollow glass spheres, microspheres made of other materials, e.g. polymeric microspheres, silica and / or silicates; nucleating agents; blowing agents; compounding agents; stabilizers and / or anti-aging agents, e.g. primary and / or secondary antioxidants and / or light stabilizers.

[0159] The adhesive layer can optionally be foamed, resulting in advantageous further developments of the invention. In other advantageous embodiments of the invention, however, the adhesive is unfoamed. Whether or not foaming is used depends, for example, on the intended application of the adhesive. For instance, foamed adhesives can increase the shock absorption effect, enabling the adhesive to absorb or dissipate impact energy within the adhesive film.

[0160] Foaming can be achieved using any chemical and / or physical methods. However, a foamed pressure-sensitive adhesive compound according to the invention is preferably obtained by introducing and subsequently expanding microballoons. "Microballoons" are defined as elastic, and therefore expandable in their ground state, hollow microspheres that have 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. Suitable low-boiling liquids include hydrocarbons of the lower alkanes, for example, isobutane or isopentane, which are enclosed as a liquefied gas under pressure within the polymer shell.

[0161] When the microballoons are subjected to stress, particularly heat, the outer polymer shell softens. Simultaneously, the liquid propellant 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.

[0162] A wide variety of microballoon types are commercially available, differing primarily in their size (6 to 45 pm diameter in the unexpanded state) and the initial expansion temperatures required (75 to 220 °C). An example of commercially available microballoons are the Expancel® DU types (DU = dry unexpanded) from Akzo Nobel. 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 (masterbatch), for example, in ethyl vinyl acetate with a microballoon concentration of approximately 65 wt.%. Both the microballoon dispersions and the masterbatch, like the DU types, are suitable for producing a foamed pressure-sensitive adhesive according to the invention.

[0163] A foamed pressure-sensitive adhesive according to the invention can also be produced using so-called pre-expanded microballoons. With this group, the expansion takes place before the microballoons are mixed into the polymer matrix. Pre-expanded microballoons are commercially available, for example, under the name Dualite® or with the type designation DE (Dry Expanded).

[0164] The density of the adhesive films, in the case of foamed adhesive layers, is preferably between 200 kg / m². 3 and 1000 kg / m² 3 , preferably between 500 kg / m² 3 and 980 kg / m² 3 , preferably between 700 kg / m 3 and 950 kg / m² 3 .

[0165] Preferably, the poly(meth)acrylates are crosslinked with a crosslinker-accelerator system.

[0166] A particularly preferred crosslinker-accelerator system comprises at least one epoxy group-containing substance as a crosslinker and at least one accelerator substance that accelerates the crosslinking reaction at temperatures below the melting point of the poly(meth)acrylate. The system requires that the polymers contain functional groups capable of crosslinking with epoxy groups. Suitable epoxy group-containing substances include multifunctional epoxides, especially bifunctional or trifunctional epoxides (i.e., those with two or three epoxide groups, respectively), but also higher-functional epoxides or mixtures of differently functional epoxides. Preferably, amines (formally considered as substitution products of ammonia), for example, primary and / or secondary amines; in particular, tertiary and / or multifunctional amines, can be used as accelerators.Substances containing multiple amine groups can also be used, whereby these TI.

[0167] The amine groups can be primary, secondary, and / or tertiary, particularly diamines, triamines, and / or tetramines. Specifically, amines are chosen that undergo no or only minimal reactions with the polymer building blocks. Phosphorus-based compounds, such as phosphines and / or phosphonium compounds, can also be used as accelerators.

[0168] Suitable functional groups for the poly(meth)acrylate to be crosslinked include acid groups (e.g., carboxylic acid, sulfonic acid, and / or phosphonic acid groups), hydroxyl groups, acid anhydride groups, epoxy groups, and / or amine groups. The polymer particularly preferably contains incorporated acrylic acid and / or methacrylic acid.

[0169] However, it can also be advantageous to forgo accelerators, as these can tend to yellow, for example (especially nitrogen-containing substances). Epoxycyclohexyl derivatives are suitable crosslinkers that do not require the addition of accelerators, particularly when carboxylic acid groups are present in the poly(meth)acrylate to be crosslinked. This can be achieved, for example, by incorporating at least 5 wt% acrylic acid into the polymer. It is particularly advantageous that the polymer to be crosslinked contains no proton acceptors, no electron pair donors (Lewis bases), and / or no electron pair acceptors (Lewis acids). The absence of these substances refers in particular to externally added accelerators, i.e., those not incorporated into the polymer backbone; however, it is especially preferred that neither externally added nor incorporated accelerators, and in particular no accelerators at all, are present.The crosslinking agent is particularly preferred as an epoxycyclohexyl carboxylate, especially (3,4-epoxycyclohexane)methyl-3,4-epoxycyclohexyl carboxylate (Uvacure® 1500).

[0170] The adhesive compound according to the invention can be used as such, e.g., in the form of a layer or a carrier-free layer of the adhesive compound according to the invention, which is also referred to as "transfer tape". Such a transfer tape is preferably applied only to a material that temporarily serves to protect the adhesive surface, to facilitate handling, and to make the adhesive compound easier to apply. Such materials are also referred to as release liners or simply as "liners" and are generally easily removable, particularly by means of suitable surface coatings. The second side of the transfer tape can also be provided with a liner.

[0171] Release liners are carrier materials that are coated or treated with an anti-adhesive finish on one or, preferably, both sides. Suitable carrier materials for release liners include various papers, optionally in combination with a stabilizing extrusion coating. Other suitable liner carrier materials are films, especially polyolefin films, for example, based on ethylene, propylene, butylene, and / or hexylene. Preferred carrier materials are papers, such as glassine papers. Papers are preferred, not least because the concept of using components derived from renewable raw materials can thus be extended to the adhesive tape's auxiliary materials.

[0172] Silicone systems are frequently used as anti-adhesive release liners. Commonly used liners include, for example, siliconized papers and siliconized films.

[0173] For using the transfer tape to bond to a substrate surface, the liner(s) are removed, allowing both adhesive sides to make direct contact with the substrate surfaces to be bonded. The liner is therefore not a component in the tape itself and is not considered part of the tape; rather, it merely serves as an aid for handling the tape.

[0174] The adhesive compound according to the invention is preferably used in the construction or production of multilayer adhesive tapes. Such multilayer adhesive tapes typically comprise at least one carrier layer and can have an outer layer of the adhesive compound according to the invention on one or both sides. In the case of double-sided adhesive tapes, either one or both outer layers can be adhesive compounds according to the invention. In the latter case, the adhesive layers can differ with respect to their chemical composition and / or their chemical and / or physical properties and / or their geometry (e.g., layer thickness); however, they are particularly preferably identical with respect to their chemical composition and / or their chemical and / or physical properties.Even with multi-layered adhesive tapes, one or both outer adhesive layers can be covered with liners.

[0175] The adhesive tapes may have additional layers, e.g., additional backing layers, functional layers, or the like.

[0176] Bio-based materials are preferably selected as backing materials for the multilayer adhesive tape, for example, those selected from the following list: papers; bio-based woven or nonwoven fabrics, for example, made of cotton or viscose; cellophane; cellulose acetate; bio-based polyethylene (PE) and polypropylene (PP) films; films made of thermoplastic starch; bio-based polyester films, e.g., films made of polylactic acid (PLA), polyethylene terephthalate (PET), polyethylene tetrahydrofuranoate (PEF), or polyhydroxyalkanoate (PHA). A PET film is particularly preferred as the backing material. PET films are preferred, for example, because they can be used as a recycled material and thus meet the requirements of sustainability.

[0177] Another object of the invention is therefore an adhesive tape comprising a carrier material and, at least on one of its two outer surfaces, preferably on both outer surfaces, an adhesive compound according to the invention. Preferably, the carrier material is a PET film. The PET film preferably has a thickness of 1 to 5 pm; the layer(s) of the adhesive compound according to the invention preferably each have a thickness of 20 to 30 pm. The preferred overall thickness of the adhesive tape according to the invention is thus 41 to 65 pm. In a preferred embodiment, a PET film made from recycled material is used as the carrier material.

[0178] For the adhesion of the pressure-sensitive adhesive to the carrier or another substrate, it can be advantageous to treat the adhesive and / or the substrate with corona or plasma before coating. Furthermore, for the adhesion of the pressure-sensitive adhesive layer to subsequent layers, especially to a carrier layer, it can be advantageous to use chemical bonding, e.g., via a primer.

[0179] Another object of the invention is the use of an adhesive compound or adhesive tape according to the invention for the production of bonds in electronic, optical and / or precision mechanical devices.

[0180] Production of the adhesive compound by hot melt process and production process from solution

[0181] Various methods for producing an adhesive compound starting from a poly(meth)acrylate, in particular by hot melt process and solution-based processes, are known in the literature.

[0182] In the hot melt process, the poly(meth)acrylate is heated to a temperature at which it transitions into a flowable melt. This process is also referred to in the present disclosure as "melting one or more poly(meth)acrylates." This melting process takes place in special melting units or extruders that ensure uniform heating and mixing of the polymer. Depending on the requirements, additives necessary for the production of the pressure-sensitive adhesive, such as plasticizers, adhesive-enhancing resins, stabilizers, mineral fillers, and polymer fillers, in particular expanded or expandable or other micro-hollow spheres, can be added before, during, or after the melting process.The coating of the hot melts to form an adhesive layer can be carried out using hot melt coating nozzles known to those skilled in the art, or preferably using roller coating units, also called coating calenders. The coating calenders can advantageously consist of two, three, four, or more rollers.

[0183] All hot melt technologies known to those skilled in the art can be used for mixing and conveying to produce pressure-sensitive adhesives using the hot melt process. The adhesives can be produced, for example, in batch sigma or Z kneaders with appropriate temperature control and with or without vacuum for degassing or purification, if necessary. Alternatively, the adhesives can also be produced in continuous processes, such as single-screw extruders, twin-screw extruders, multi-screw or ring extruders, planetary roller extruders, and the like, also with or without vacuum for degassing or purification, if necessary.

[0184] In one embodiment, the adhesive compound is produced by coating using the hot melt process. This embodiment is particularly advantageous for thicker adhesive layers, especially for layers larger than 200 pm.

[0185] In the solution-based process, the poly(meth)acrylate is dissolved in a suitable solvent. This process is also referred to in the present disclosure as "dissolving one or more poly(meth)acrylates in a solvent." This solution is then further processed by adding additives such as plasticizers, adhesion-enhancing resins, and stabilizers to improve the properties of the adhesive. The poly(meth)acrylate adhesive solution is applied to the desired substrate, which can be done by brushing, dipping, or spraying. After the solution has been applied, the solvent evaporates, leaving behind a uniform layer of the pressure-sensitive adhesive. To ensure complete drying and curing of the adhesive, heating or a vacuum can be used to guarantee rapid and complete evaporation of the solvent.

[0186] In one embodiment, the pressure-sensitive adhesive is produced by a solution coating process. This embodiment is particularly advantageous for thinner pressure-sensitive adhesive layers, especially for layers less than or equal to 200 pm. In the context of the present disclosure, dissolving the pressure-sensitive adhesive and the manufacturing process from solution also include dispersions of the pressure-sensitive adhesive in the solvent.

[0187] Version 1

[0188] According to one embodiment of the present disclosure, the adhesive compounds according to the invention are produced by a hot melt process.

[0189] Version 2

[0190] In one embodiment, the manufacturing process of the adhesive compound according to the invention comprises the process steps: a) providing one or more poly(meth)acrylates; b) melting one or more poly(meth)acrylates; c) applying the melt obtained from step b) as a layer to a coating unit.

[0191] Version 3

[0192] In a further development of embodiment 2, the provision of the one or more poly(meth)acrylates in step a) takes place in a closed shell, preferably in a bag, particularly preferably in a thermoplastic bag; and the process further comprises melting the poly(meth)acrylates at a temperature which is higher than the melting temperature of the closed shell.

[0193] Version 3a

[0194] In one embodiment, the manufacturing process of the adhesive compound according to the invention comprises the following process steps: a) providing one or more poly(meth)acrylates in a closed shell, preferably in a bag, particularly preferably in a thermoplastic bag; b) melting the one or more poly(meth)acrylates at a melting temperature that is higher than the melting point of the closed shell; c) applying the melt obtained from step b) as a layer to a coating unit.

[0195] In embodiment 3a, one or more poly(meth)acrylates are melted together with the closed shell(s) and applied to a coating unit in a further process step.

[0196] Design 4

[0197] In a further development of the aforementioned process, the provision of the one or more poly(meth)acrylates in step a) takes place in a closed shell, preferably in a bag, particularly preferably in a thermoplastic bag; and the process further comprises melting the poly(meth)acrylates at a temperature which is lower than the melting temperature of the closed shell.

[0198] embodiment 4a

[0199] In one embodiment, the manufacturing process of the adhesive compound according to the invention comprises the following process steps: a) providing one or more poly(meth)acrylates in a closed shell, preferably in a bag, particularly preferably in a thermoplastic bag; b) melting the one or more poly(meth)acrylates at a melting temperature that is lower than the melting point of the closed shell; c) applying the melt obtained from step b) as a layer to a coating unit.

[0200] In embodiment 4a, one or more poly(meth)acrylates are melted to form a melt, the closed shell being mechanically comminuted and, after a further process step in which the melt is applied to a coating unit, being dispersed in the pressure-sensitive adhesive.

[0201] Embodiment 5 According to one aspect of the present disclosure, the adhesive compounds according to the invention are produced from solution by a process.

[0202] Producing the adhesive compound according to the invention from a solution allows for the application of thinner layers compared to the application of layers using the hot melt process. Furthermore, producing the adhesive compound according to the invention from a solution allows for a wider adjustable viscosity range compared to the hot melt process.

[0203] In a further development of this embodiment 5, the solvent used to dissolve the poly(meth)acrylate compounds is recovered to a greater than 95%, preferably greater than 98%, relative to the amount of solvent used, and preferably reused in the process, thereby achieving a substantially net solvent-free process. This further development is also transferable to other manufacturing processes that involve dissolving the poly(meth)acrylate compounds.

[0204] Version 5a

[0205] In a preferred aspect, the manufacturing process of the pressure-sensitive adhesive according to the invention comprises the process steps: a) providing one or more poly(meth)acrylates; b) dissolving the one or more poly(meth)acrylates in a solvent; c) applying the solution obtained from step b) as a layer to a coating unit.

[0206] Design 6

[0207] According to another aspect of the present disclosure, the adhesive compounds according to the invention are produced by a process which comprises melting and dissolving one or more poly(meth)acrylates.

[0208] Version 6a

[0209] In one embodiment, the manufacturing process of the adhesive compound according to the invention comprises the following process steps: a) providing one or more poly(meth)acrylates; b) melting one or more poly(meth)acrylates; c) dissolving one or more poly(meth)acrylates from the melt from process step b) in a solvent; d) applying the solution obtained from step c) as a layer to a coating unit.

[0210] Design 6b

[0211] In one embodiment, the manufacturing process of the pressure-sensitive adhesive according to the invention comprises the following process steps: a) providing one or more poly(meth)acrylates in a closed casing, preferably in a bag, particularly preferably in a thermoplastic bag; b) melting the one or more poly(meth)acrylates at a melting temperature that is higher than the melting point of the closed casing; c) dissolving the one or more poly(meth)acrylates from the melt from process step b) in a solvent; d) applying the solution obtained from step c) as a layer to a coating unit.

[0212] Design 6c

[0213] In one embodiment, the manufacturing process of the pressure-sensitive adhesive according to the invention comprises the following process steps: a) providing one or more poly(meth)acrylates in a closed casing, preferably in a pouch, particularly preferably in a thermoplastic pouch; b) melting the one or more poly(meth)acrylates at a melting temperature lower than the melting point of the closed casing; c) dissolving the one or more poly(meth)acrylates from the melt from process step b) in a solvent; d) applying the solution obtained from step c) as a layer to a coating unit. Embodiment 6d

[0214] In one embodiment, the manufacturing process of the pressure-sensitive adhesive according to the invention comprises the following process steps: a) providing one or more poly(meth)acrylates in a closed casing, preferably in a bag, particularly preferably in a thermoplastic bag; b) melting the one or more poly(meth)acrylates at a melting temperature that is lower than the melting point of the closed casing; c) filtering the melt from process step b); d) dissolving the one or more poly(meth)acrylates from the filtered melt from process step c) in a solvent; e) applying the solution obtained from step d) as a layer to a coating unit.

[0215] The filtration in process step c) serves in particular to filter out the shell (previously closed shell) that has been broken down by the process from the one or more poly(meth)acrylates.

[0216] Version 7

[0217] In one embodiment, the manufacturing process of the adhesive compound according to the invention comprises the following process steps: a) providing one or more poly(meth)acrylates in a closed casing, preferably in a bag, particularly preferably in a thermoplastic bag; b) comminuting the closed casing filled with one or more poly(meth)acrylates; c) dissolving one or more poly(meth)acrylates from process step b) in a solvent; d) filtering the solution obtained from process step c); e) applying the solution obtained from step d) as a layer to a coating unit.

[0218] In embodiment 8, in a further development of the process, the provision of the one or more poly(meth)acrylates in step a) takes place in a closed shell, preferably in a bag, particularly preferably in a thermoplastic bag; and the process comprises the process steps d) comminution of the closed shell filled with one or more poly(meth)acrylates; and e) filtering the comminution of the shell from the one or more poly(meth)acrylates.

[0219] Version 9

[0220] In one embodiment, the poly(meth)acrylate has a volatile organic compound content, determined gravimetrically according to the description, of less than 5.0 wt%; a weight-average molecular weight, determined by gel permeation chromatography according to the description, of more than 500,000 g / mol; and a gel content, determined according to the description, of less than 5 wt%; wherein the wt% refer to 100 parts by weight of the poly(meth)acrylate.

[0221] Design 10

[0222] In a further development according to embodiment 9, the content of volatile organic compounds is less than 3.0 wt.%, particularly preferably less than 2.0 wt.%, most preferably less than or equal to (<) 1.5 wt.%.

[0223] Design 11

[0224] In a further development of embodiments 9 or 10, the weight-average molecular weight is more than 700,000 g / mol, particularly preferably more than 900,000 g / mol, or even more than 1,000,000 g / mol.

[0225] Design 12

[0226] In a further development of embodiments 9 to 11, the gel content is less than 2 wt.%, particularly preferably less than 1 wt.%, wherein the wt.% refer to 100 parts by weight of the poly(meth)acrylate.

[0227] Embodiment 13 Another embodiment relates to a process for the production of a poly(meth)acrylate according to one of embodiments 9 to 12, wherein a monomer composition comprising (a) acrylic acid esters and / or methacrylic acid esters of the formula CH2=C(R I )(COOR 11 ), wherein R 1(a) (H or CH3 and R) is an alkyl group with 1 to 30 C atoms, more preferably with 4 to 14 C atoms, particularly preferably with 4 to 9 C atoms; (b) olefinically unsaturated monomers with functional groups exhibiting reactivity with crosslinking agents; and optionally further olefinically unsaturated monomers that are copolymerizable with monomers (a) and (b) by bulk polymerization with less than 5 wt.-%, solvent, based on the total mass of reaction substrate used, are converted into a polymer, characterized in that the substance polymerization is carried out using a first polymerization regulator, which is a compound containing an -SH group, and a second polymerization regulator, which is a compound containing an -OH group, wherein the first and the second polymerization regulators are used in a total amount of about 0.001 parts to about 10 parts by weight per 100 parts of the total amount of monomers to be polymerized.

[0228] Version 14

[0229] In a further development of embodiment 13, the first polymerization regulator is essentially consumed during polymerization and the second polymerization regulator is present after polymerization in a proportion of at least 60% of the amount used.

[0230] Version 15

[0231] In a further development of embodiments 13 or 14, the transfer constants of the first polymerization regulator k satisfy CTA1 and the transfer constants of the second polymerization regulator k CTA2 the condition k CTA1 > 100 CTA2

[0232] Version 16

[0233] In a further development of embodiments 13 to 15,

[0234] - the first polymerization regulator a thioalcohol; and

[0235] - the second polymerization regulator is an alcohol or an adhesive-enhancing resin; preferably a secondary alcohol, a terpene phenol resin or a rosin resin.

[0236] embodiment 17

[0237] In a further development of embodiments 13 to 16, 0.01 to 0.03 wt.% of the first polymerization regulator is used in the polymerization, wherein the wt.% used refers to an addition to 100 wt.% of the monomers to be polymerized.

[0238] Design 18

[0239] In a further development of embodiments 13 to 17, 0.5 to 5.0 wt.%, preferably 0.8 to 3.0 wt.%, particularly preferably 1.0 to 1.5 wt.% of the second polymerization regulator is used in the polymerization, wherein the wt.% used are added to 100 wt.% of the monomers to be polymerized.

[0240] Design 19

[0241] In a further development of embodiments 13 to 18, the polymerization is selected from a syrup polymerization; a polymerization in a reactor and a polymerization in a closed shell, preferably in a bag, particularly preferably in a thermoplastic bag.

[0242] Design 20

[0243] In a further development of embodiments 13 to 19, the process is carried out as a batch process.

[0244] Version 21

[0245] In one embodiment, the poly(meth)acrylate produced according to one of embodiments 9 to 12 or according to one of embodiments 13 to 20 is used to produce an adhesive.

[0246] Version 22

[0247] In a further development of the use of embodiment 21 (a) one or more poly(meth)acrylates according to one of embodiments 9 to 12 or of a poly(meth)acrylate produced according to embodiments 13 to 20 is provided; (b) the provided one or the provided multiple poly(meth)acrylates are dissolved in a solvent; and (c) the solution obtained from step (b) is applied as a layer on a coating unit onto a substrate.

[0248] Version 23

[0249] In a further development of the use of embodiment 21 (a), one or more poly(meth)acrylates are provided in a closed shell, preferably in a bag, particularly preferably in a thermoplastic bag; (b) one or more poly(meth)acrylates in the closed shell are melted at a temperature which is higher than the melting temperature of the closed shell to produce a molten mass; and (c) the molten mass is applied to a substrate by a coating unit.

[0250] Version 24

[0251] In a preferred embodiment, the process for producing one or more poly(meth)acrylates, which have a volatile organic compound content of less than 5 wt%, comprises the steps: i. providing a (meth)acrylate monomer composition to be polymerized; ii. providing a first polymerization regulator; iii. providing a second polymerization regulator; iv. polymerizing the monomer composition to be polymerized i. in the presence of the first polymerization regulator ii. and the second polymerization regulator ill.

[0252] Measurement and testing methods

[0253] Determination of the gel content

[0254] The carefully dried, solvent-free adhesive samples are sealed in a polyethylene (Tyvek) nonwoven bag. To determine the gel value after polymerization, a defined quantity of the polymer, optionally in a closed bag, is homogenized in a kneader and sealed in a polyethylene (Tyvek) nonwoven bag. The gel value, i.e., the fraction of the polymer by weight that is not soluble in toluene, is determined from the difference in sample weights before and after extraction with ethyl acetate. If a closed bag is present during polymerization and homogenization, this determines the zero value, as it is also present in the reference sample.

[0255] Determination of molecular weight

[0256] The data on the number-average molar mass M n and the weight-average molar mass M wThis document refers to the well-known determination 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.

[0257] A PSS-SDV type column, 5 pm, 10 is used as the upstream column. 3 Ä, 8.0 mm x 50 mm (Specifications here and below in the order: type, particle size, porosity, inner diameter x length; 1 Ä = 10' 1 ° m). A combination of PSS-SDV, 5 pm, 10 columns is used for separation. 3 Ä and 10 5 A and 10 6Columns 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 was performed using the commercially available ReadyCal kit Poly(styrene) high from PSS Polymer Standard Service GmbH, Mainz. The values ​​were universally converted to polymethyl methacrylate (PMMA) using the Mark Houwink parameters K and alpha, so that the data were given in PMMA mass equivalents.

[0258] Determination of shear strength (“SSZ 23°C; 1 kg” and “SSZ 70°C; 0.5 kg”) The shear strength was determined by the shear strength under a test climate of 23 + / -1 °C temperature and 50 % + / - 5 % relative humidity (“SSZ 23°C; 1 kg”).

[0259] 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 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.

[0260] 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.

[0261] 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.

[0262] The prepared plate was attached to a clock via the adapter plate using a hook; a 1 kg weight was then smoothly hung in the strap loop.

[0263] The winding time between rolling and loading was 12 minutes. The time in minutes until adhesive failure was measured; the results are averaged from three measurements. A shear life of over 10,000 minutes is considered a good result.

[0264] The determination of the shear life under a test climate of 70 ± 1 °C and 10% ± 10% relative humidity ("SSZ 70°C; 0.5 kg") is carried out analogously to the above procedures, whereby the prepared plate was equilibrated for 30 minutes under the test conditions at 70 °C before a 0.5 kg weight was suspended. A shear life at 70 °C of over 10,000 minutes is considered a good result.

[0265] Adhesive strength of steel

[0266] The adhesive strength was determined under a test climate of 23 °C ± 1 °C and 50% ± 5% relative humidity. The samples were cut to a width of 20 mm and adhered to a steel plate (ASTM). The steel plate was cleaned and conditioned before measurement. For this, the plate was first wiped with solvent and then left to air dry for 5 minutes to allow the solvent to evaporate. The side of the adhesive tape facing away from the test substrate was then covered with 25 µm thick etched PET film, preventing the sample from stretching during measurement. The test sample was then rolled onto the substrate. For this, the tape was rolled back and forth five times with a 4 kg roller at a winding speed of 10 m / min. One minute after rolling, the plate was inserted into a special holder.The adhesive strength was measured using a Zwick tensile testing machine; the samples were peeled off at an angle of 180° at a speed of 300 mm / min. The measurement results are given in N / cm and are averaged from five individual measurements.

[0267] K-value (according to Fikentscher)

[0268] The K-value is a measure of the average molecular size of high-polymer substances. For measurement, one percent (1 g / 100 mL) toluene polymer solutions were prepared and their kinematic viscosities were determined using a Vogel-Ossag viscometer. After normalization to the viscosity of toluene, the relative viscosity is obtained, from which the K-value can be calculated according to Fikentscher (Polymer 1967, 8, 381 ff).

[0269] Gel permeation chromatography GPC

[0270] The weight-mean molecular weight (Mw) and polydispersity (PD) values ​​given in this document refer to determination by gel permeation chromatography. 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 performed at 25 °C. A PSS-SDV, 5 p, 10 column is used as the guard column. 3 Ä, ID 8.0 mm ■ 50 mm is used. For separation, columns of type PSS-SDV, 5 p, 10 are used. 3 Columns 105 and 106, each with an ID of 8.0 mm x 300 mm, were used (Polymer Standards Service columns; detection via Shodex RI71 differential refractometer). The flow rate is 1.0 ml per minute. Calibration is performed against PMMA standards (polymethyl methacrylate calibration).

[0271] Determination of volatile organic compounds (VOCs)

[0272] The volatile organic compounds (VOCs) of one or more poly(meth)acrylates are determined gravimetrically. Approximately 1 g of poly(meth)acrylate is weighed out, then dried for 3 hours at 120°C, and subsequently weighed again. The percentage by weight of the VOCs is determined from the mass difference before and after drying. Table 1: Commercially available chemicals used

[0273] Production of poly(meth)acrylates

[0274] Preparation by polymerization in a reactor (RP): For the polymerization of polymer P1, a 2-liter laboratory kneader was filled with 10 g of acrylic acid, 495 g of butyl acrylate (BA) and 495 g of 2-ethylhexyl acrylate (2-EHA) (monomer composition M1), as well as 3 g of VAZO88, 0.2 g of 1-dodecanethiol, and 10 g of isopropyl alcohol. After passing nitrogen gas through the kneader for 45 minutes while stirring, it was heated to 70°C at an absolute pressure of 200 mbar and maintained at this temperature. The heat of polymerization was monitored by evaporating the reaction mixture and by condensing it on a condenser. 30 minutes after the start of the reaction, the pressure was increased to 1 bar. After another hour of reaction time, the reaction was stopped and the mixture was cooled to room temperature.

[0275] The polymer P4 was polymerized in an analogous manner, with the monomer composition, initiator and polymerization regulator being adjusted according to Tables 2 and 3.

[0276] Production by polymerization in a closed shell (GH)

[0277] For the production of polymer P2, a reaction mixture consisting of 3 g acrylic acid (AA), 48.5 g butyl acrylate (BA), and 48.5 g 2-ethylhexyl acrylate (2-EHA) (monomer composition M2), as well as 0.3 g Omnirad 184, 0.02 g 1-dodecanethiol, and 1 g isopropyl alcohol, was filled into the bag prepared as described above using a liquid forming, filling, and sealing machine. The reaction mixture was inertized by passing nitrogen through it for 30 minutes. The bag was then sealed at the top in a transverse direction. The thickness of the filled bag was 8 mm.

[0278] The bag was placed in a water bath heated to 20 °C, ensuring it was completely submerged. A Heraeus Semray LIV2000 LED 365 nm UV lamp was positioned 23 cm apart on both the top and bottom of the bag. The lamps were illuminated for 10 minutes at an intensity of 10 mW / cm², as determined by the described setup. 2 irradiated. After hardening, the polymer is stored in a cool, dark place until further processing.

[0279] The polymers P5, P2-C1, P2-C2, and P2-C3 were polymerized in an analogous manner, with the monomer composition, initiator, and polymerization regulator being adjusted according to Tables 2 and 3.

[0280] Preparation by Syrup Polymerization (SP): For the polymerization of polymer P3, 2-ethylhexyl acrylate (2-EHA), butyl acrylate (BA), and acrylic acid (AA) were mixed in a weight ratio of 47.5:47.5:5 (monomer composition M3) to produce 100 parts by weight of a monomer mixture. To the monomer mixture, 0.05 parts by weight of Omnirad-184, 0.02 parts by weight of 1-dodecanethiol, and 1.0 part by weight of isopropyl alcohol were added. After passing nitrogen gas through the mixture for 45 minutes with stirring, the mixture was prepolymerized using a Heraeus Semray LIV2000 LED 365 nm UV lamp to obtain a prepolymer with a viscosity of approximately 5,000 cP (centipoise). Subsequently, 0.25 parts by weight of Omnirad-184 were added to the prepolymer. The photocurable adhesive composition was applied between two release layers using a pilot coater to form an adhesive layer of 2000 pm. Curing conditions, step 1: UV intensity of 3.0 W / cm² 2, Dwell time = 90 seconds Step 2: UV intensity of 10 W / cm² 2 Residence time = 210 seconds. After curing, the polymer is separated from the release layers and stored in a cool, dark place until further processing.

[0281] The polymer P6 was polymerized in an analogous manner, with the monomer composition, initiator and polymerization regulator being adjusted according to Tables 2 and 3.

[0282] Table 2: Monomer composition (MZ) of poly(meth)acrylates

[0283] 1 based on the monomer composition of poly(meth)acrylate [monomers a) + monomers b) + monomers c) yield 100 parts by weight of poly(meth)acrylate].

[0284] Table 3: Poly(meth)acrylates and manufacturing processes, where RP stands for reactor polymerization, GH for closed shell polymerization, SP for syrup polymerization, MZ for monomer composition, CTA-1 for first polymerization regulator and CTA-2 for second polymerization regulator.

[0285] 2 Addition to 100 parts by weight of the monomer composition (MZ) of the poly(meth)acrylate.

[0286] Table 4: Measurement results of the poly(meth)acrylates from Table 3, where VOC stands for volatile organic compounds, monomer conversion refers to the monomers converted in the polymerization in wt% of the monomer composition (MZ), and MW stands for weight mean molecular weight.

[0287] 3 Not measurable (nm) due to the high gel content;

[0288] *The detection limit of GC-MSD is 10 ppm and was not exceeded.

[0289] The monomer conversion and residual content of the first polymerization regulator, CTA-1, and the second polymerization regulator, CTA-2, after polymerization were determined by gas chromatography. For this purpose, the corresponding monomers were extracted from the polymer sample in butanone. Gas chromatography with a mass-selective detector (GC-MSD) according to DIN EN ISO / IEC 17025 was used to determine the individual components. The residual content of a polymerization regulator is the ratio of the amount of polymerization regulator present after polymerization to the amount of polymerization regulator used for polymerization. The residual content of the second solid polymerization regulator, CTA-2 (Foral 85 and TP 110), was determined by gel permeation chromatography (GPC) in the same manner.

[0290] In a direct comparison of polymers with the same comonomer composition P2 to P2-C1, P2-C2, and P2-C3, a higher K-value is observed at a lower gel content. This is an advantageous effect for adhesive applications.

[0291] Due to its high VOC content of 7.3%, product P2-C5 could not be safely processed further. Products with a VOC content exceeding 5% were not considered part of the substance polymerization process according to the invention.

[0292] Manufacturing process of pressure-sensitive adhesives

[0293] Production of pressure-sensitive adhesives from solvent (L)

[0294] The prepared poly(meth)acrylate (e.g., P1) was dissolved in ethyl acetate. Optionally, the mixture was filtered through a 10 µm filter. The mixture was then blended with crosslinkers and, optionally, adhesive resin according to the formulation (e.g., F1 for polymer P1) in Table 5. The resulting composition was applied from solution to a siliconized release film (50 µm polyester) using a doctor blade and subsequently dried (coating speed 2.5 m / min, drying tunnel 15 m, temperatures Zone 1: 40 °C, Zone 2: 70 °C, Zone 3: 95 °C, Zone 4: 105 °C). The mass deposition after drying was 50 g / m². 2 The adhesive tape obtained was then tested. The results are listed in Table 6.

[0295] The pressure-sensitive adhesive for formulation F10 was produced using polymer P3 in an analogous manner.

[0296] Manufacturing process for pressure-sensitive adhesives using hot-melt (HM) processes

[0297] The base polymer (e.g., polymer P2) was largely freed of VOCs using a twin-screw extruder (Berstorff GmbH, Germany). The following parameters were selected: the screw speed was 150 l / min, the motor current 15 A, and a throughput of 29.0 kg / h was achieved. To remove VOCs, a vacuum was applied to three different domes (vacuum dome). The vacuum pressures ranged from 20 mbar to 300 mbar. The hot melt exit temperature was approximately 115 °C.

[0298] The polymer was then fed into a planetary roller extruder (PWE). The crosslinker PGE and, optionally, the adhesive resin were added via metering ports according to formulation F2 in Table 5. All components were mixed to form a homogeneous polymer melt.

[0299] The polymer melt was transferred to a twin-screw extruder using a melt pump. The accelerator component IPD was added via a metering port according to the formulation (e.g., F2 for polymer P2) in Table 5. The entire mixture was then purged of all gas inclusions in a vacuum chamber V at a pressure of 175 mbar. The resulting melt mixture was then transferred to a die.

[0300] After exiting the nozzle, the melt mixture was sandwiched between two release agents, which could be reused after removal (process liner), and formed into a web using a roller calender. The mass deposition was 100 g / m². 2 The adhesive tape obtained was then tested. The results are listed in Table 6.

[0301] Similarly, the pressure-sensitive adhesives with formulations F2, F4, F6, F2-C1, F2-C2 and F2-C3 were produced with the corresponding polymers.

[0302] Production of pressure-sensitive adhesives from hot melt and solvent (HM+L): The base polymer (e.g., polymer P2) was fed into a planetary roller extruder (PWE). Additional components can be added optionally via metering ports. All components were mixed at 140°C to form a homogeneous polymer melt.

[0303] The polymer melt was then dissolved in ethyl acetate. The mixture was then blended with crosslinkers and, optionally, adhesive resin according to the formulation (e.g., F3 for polymer P2) in Table 5. The resulting composition was applied from solution to a siliconized release film (50 µm polyester) using a doctor blade and subsequently dried (coating speed 2.5 m / min, drying tunnel 15 m, temperatures Zone 1: 40 °C, Zone 2: 70 °C, Zone 3: 95 °C, Zone 4: 105 °C). The mass deposition after drying was 50 g / m². 2 The adhesive tape obtained was then tested. The results are listed in Table 6.

[0304] Production of pressure-sensitive adhesives from hot melt with filtration (HM+F)

[0305] The base polymer (e.g. polymer P2) was heated to 100°C using a single-screw extruder (Berstorff GmbH, Germany) and filtered through a 50pm filter.

[0306] The filtered polymer was largely freed of VOCs using a twin-screw extruder (Berstorff GmbH, Germany). The following parameters were selected: the screw speed was 150 l / min, the motor current 15 A, and a throughput of 29.0 kg / h was achieved. To remove VOCs, a vacuum was applied to three different domes (vacuum dome). The vacuum pressures ranged from 20 mbar to 300 mbar. The hot melt exit temperature was approximately 115 °C.

[0307] The polymer was then fed into a planetary roller extruder (PWE). The crosslinker PGE and, optionally, the adhesive resin were added via metering ports according to formulation F9 in Table 5. All components were mixed to form a homogeneous polymer melt.

[0308] The polymer melt was transferred to a twin-screw extruder using a melt pump. The accelerator component IPD was added via a metering port according to the formulation (e.g., F9 for polymer P2) in Table 5. The entire mixture was then purged of all gas inclusions in a vacuum chamber V at a pressure of 175 mbar. The resulting melt mixture was then transferred to a die.

[0309] After exiting the nozzle, the melt mixture was sandwiched between two release agents, which could be reused after removal (process liner), and formed into a web using a roller calender. The mass deposition was 100 g / m². 2 The resulting adhesive tape was then tested. The results are listed in Table 6. Production of the pressure-sensitive adhesives from hot melt with filtration and solvent (HM+F+L)

[0310] The base polymer (e.g., Polymer P2) was heated to 100°C using a single-screw extruder (Berstorff GmbH, Germany) and filtered through a 25 pm filter. The filtered polymer was dissolved in ethyl acetate. Optionally, the mixture was filtered through a 1 opm filter. The mixture was then blended with crosslinkers and, optionally, adhesive resin according to the formulation (e.g., F8 for Polymer P2) in Table 5. The resulting composition was applied from solution to a siliconized release film (50 pm polyester) using a doctor blade and subsequently dried (coating speed 2.5 m / min, drying tunnel 15 m, temperatures Zone 1: 40°C, Zone 2: 70°C, Zone 3: 95°C, Zone 4: 105°C). The mass deposition after drying was 100 g / m². 2 The adhesive tape obtained was then tested. The results are listed in Table 6.

[0311] Table 5: Composition of the pressure-sensitive adhesives and manufacturing method, where L stands for the solvent-based manufacturing process, HM for the hot melt manufacturing process and F for a filtration step.

[0312] 4 The stated wt% refers to the mass composition of the pressure-sensitive adhesive [polyacrylate + optional adhesive resin make up 100 parts by weight]; 5 Crosslinker (data based on 100 parts by weight of polyacrylate) additive to 100 parts by weight of pressure-sensitive adhesive (polyacrylate + optional adhesive resin).

[0313] Table 6: Measurement results of the pressure-sensitive adhesives from Table 5 after coating. The shear strength was determined according to "SSZ 23°C; 1 kg". The measurements were stopped at 10,000 minutes and reported as 10,000 minutes.

[0314] The optical classification of the pressure-sensitive adhesives was determined by a haze measurement performed with a haze-gard plus device from BYK Gardner GmbH. Samples with a haze value below 5% are classified as "clear"; samples with a haze value between 5% and 20% are classified as "slightly milky." Haze is defined by ASTM D1003 as the percentage of light that deviates on average by more than 2.5° from the incident light beam.

[0315] The line pattern was assessed qualitatively by a specialist through visual inspection. The rating "Good" was chosen for samples with a smooth surface for which no [missing information - likely a specific marking or characteristic] was required.

[0316] Stripes are observable and for which no gel particles are visible;

[0317] “Poor” was chosen for samples that have a low number (1 to 10 per square meter) of stripes and gel particles;

[0318] “Very poor” was chosen for samples that have a very high number (> 10 per square meter) of streaks and gel particles.

Claims

Patent claims 1. Poly(meth)acrylate produced by a substance polymerization characterized in that the substance polymerization is carried out using a first polymerization regulator and a second polymerization regulator.

2. Poly(meth)acrylate according to claim 1, characterized in that the poly(meth)acrylate has a weight-average molecular weight of more than 500,000 g / mol, preferably more than 700,000 g / mol, particularly preferably more than 900,000 g / mol, or even more than 1,000,000 g / mol.

3. Poly(meth)acrylate according to one of the preceding claims, characterized in that the first polymerization regulator is substantially consumed during polymerization and the second polymerization regulator is present after polymerization to a proportion of at least 60% of the amount used.

4. Poly(meth)acrylate according to one of the preceding claims, characterized in that the transfer constant of the first polymerization regulator (k CTA1 ) is at least 100 times larger than the transfer constant of the second polymerization regulator (k CTA2 ).

5. Poly(meth)acrylate according to one of the preceding claims, characterized in that the first polymerization regulator is a sulfur-containing compound, preferably a compound containing at least one -SH group, and in particular preferably a thioalcohol.

6. Poly(meth)acrylate according to one of the preceding claims, characterized in that the second polymerization regulator is a compound containing at least one -OH group, preferably an alcohol.

7. Poly(meth)acrylate according to one of the preceding claims, characterized in that the second polymerization regulator is an alcohol or an adhesive-enhancing resin; preferably that the second polymerization regulator is a secondary alcohol, terpene phenol resin or rosin resin.

8. Poly(meth)acrylate according to one of the preceding claims, characterized in that 0.01 to 0.03 wt.% of the first polymerization regulator is used in the polymerization and 0.5 to 5.0 wt.%, preferably 0.8 to 3.0 wt.%, particularly Preferably, 1.0 to 1.5 wt.% of the second polymerization regulator is used, wherein the wt.% used refers to an addition to 100 wt.% of the monomers to be polymerized.

9. Poly(meth)acrylate according to one of the preceding claims, characterized in that the (meth)acrylate copolymer is produced by a substance polymerization process selected from i. syrup polymerization; ii. polymerization in a reactor; and ill. polymerization in a closed shell, preferably in a bag, particularly preferably in a thermoplastic bag.

10. Poly(meth)acrylate according to one of the preceding claims, characterized in that the poly(meth)acrylate is produced in a batch process.

11. Adhesive compound comprising one or more poly(meth)acrylates according to any one of the preceding claims 1 to 10.

12. Adhesive compound according to claim 11 comprising i. a crosslinking system, preferably a thermal crosslinking system; and / or ii. an adhesive-enhancing resin.

13. A method for producing an adhesive layer comprising the process steps of: a) providing one or more poly(meth)acrylates according to any one of claims 1 to 9; b) dissolving one or more poly(meth)acrylates in a solvent; c) applying the solution obtained from step b) as a layer to a coating unit.

14. Method according to claim 13 characterized in that the provision of the one or more poly(meth)acrylates in step a) takes place in a closed casing, preferably in a bag, particularly preferably in a thermoplastic bag; and the process further comprises melting one or more poly(meth)acrylates at a temperature higher than the melting temperature of the closed shell prior to process step b).

15. Process according to claim 13 or claim 14, characterized in that the The process includes the provision of one or more poly(meth)acrylates in a closed shell in step a); and the process comprises the process steps a2) comminution of the closed shell filled with one or more poly(meth)acrylates; and as a further process step, filtering the comminution of the one or more poly(meth)acrylates from the comminuted shell.

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