Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J9/00—Adhesives characterised by their physical nature or the effects produced, e.g. glue sticks
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
  • C09J133/04—Homopolymers or copolymers of esters
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
  • C09J7/38—Pressure-sensitive adhesives [PSA]
  • C09J7/381—Pressure-sensitive adhesives [PSA] based on macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
  • C09J7/385—Acrylic polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2312/00—Crosslinking
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2666/00—Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
  • C08L2666/02—Organic macromolecular compounds, natural resins, waxes or and bituminous materials

Definitions

• the invention relates to oriented polyacrylate PSAs, the production thereof and their use for adhesive tapes.
• the orientation of the macromolecules also plays an important role in the properties of PSAs. During the production, further processing or later (mechanical) stressing of polymers or polymer masses, high degrees of orientation of the macromolecules in preferred directions can occur in the entire polymer structure. The orientation can lead to special properties of the corresponding polymers. Some examples of properties that can be influenced by the degree of orientation are strength or Rigidity of the polymers or the plastics made from them, thermal conductivity, thermal stability and anisotropic behavior with regard to permeability to gases and liquids. Oriented polymers can also have an anisotropic tensile / elongation behavior.
• the measurement of light refraction therefore serves as a method for determining the orientation of polymers, especially in PSAs.
• Another method for determining the orientation is to measure the shrinkback in the free film.
• DE 100 34 069 describes a process for the production of oriented acrylate PSAs by means of electron radiation (ES radiation).
• DE 100 52 955 also describes the use of such oriented acrylate PSAs prepared by the process according to DE 100 34 069.
• electron beam crosslinking offers advantages. For example, certain states can be "frozen” through the crosslinking.
• electron radiation also has disadvantages. Thus, the electron beams penetrate not only the acrylic PSA but also the backing material and thus damage the PSA tape.
• the crosslinking quality is compared to other crosslinking mechanisms Usually also only limited, since the high energy also leads to a decomposition of the polymer. Furthermore, the equipment required for the ES radiation is very high.
• the object of the invention is therefore to provide an oriented acylate PSA which does not have the above-mentioned disadvantages of the prior art.
• the acylate PSA is said to have one without a large one apparatus-feasible processes can be produced and the undesirable polymer degradation of PSA and / or carrier material can be avoided.
• the main claim accordingly relates to a permanently oriented PSA which can be obtained by radical polymerization, comprising a UV-crosslinked acrylate-based polymer which 1.) is composed of at least 50% by weight of at least one acrylic monomer of the general formula (I) .
• R 1 is hydrogen (H) or a methyl group (CH 3 ) and R 2 is hydrogen (H) or an unbranched or branched, saturated d to C 30 hydrocarbon radical which may optionally be substituted by one or more functional groups and 2 .
• R 2 is hydrogen (H) or an unbranched or branched, saturated d to C 30 hydrocarbon radical which may optionally be substituted by one or more functional groups and 2 .
• the orientation of the PSA is permanently retained, the term “permanent” being used for a period of at least 30 days, in particular at least 3
• Months preferably at least 1 year, within which an initial shrinkage of the material is at most 20%, in particular at most 10%, advantageously based on the initial value, is reduced.
• the desired material properties are favored by an average molecular mass of the polymer, which should be at least 200,000 g / mol.
• the monomers used for the polymerization are chosen such that the resulting polymers can be used as pressure-sensitive adhesives at room temperature or higher temperatures, in particular such that the resulting polymers have pressure-sensitive adhesive properties in accordance with the "Handbook of Pressure Sensitive Adhesive Technology" by Donatas Satas (van Nostrand, New York 1989)
• T G of the polymers of T G ⁇ 10 ° C. the monomers are preferably selected in accordance with what has been said above and the quantitative composition of the monomer mixture is advantageously chosen such that the Fox equation ( G1) (cf. TG Fox, Bull. Am. Phys. Soc. 1 (1956) 123) gives the desired T G value for the polymer.
• n the Laui number over the monomers used
• w n the mass fraction of the respective monomer n (% by weight)
• T G n the respective glass transition temperature of the homopolymer from the respective monomers n in K.
• a compound of the general formula I is selected for the at least one acrylic monomer, in which the radical R 1 is hydrogen (H) or CH 3 and the radical R 2 is hydrogen (H) or one from the group of branched or unbranched, saturated C 4 to C 1 hydrocarbon radicals, in particular the C 4 to Cg hydrocarbon radicals, is selected and R 2 can be substituted by one or more polar and / or functional groups.
• acrylic or methacrylic acid esters are used as monomers.
• Specific, non-limiting examples 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 the branched isomers of these, for example isobutyl acrylate, 2-ethyl hexyl acrylate, 2-ethylhexyl methacrylate.
• R 2 comprises a bridged or non-bridged, substituted or unsubstituted cycloalkyl group consisting of at least 6 C atoms.
• Suitable substituents are, for example, C 1 -C 6 -alkyl radicals, halide or cyanide groups.
• Specific examples of such monomers are cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate and 3,5-dimethyladamantyl acrylate.
• monomers which contain functional or polar groups such as carboxyl, sulfonic acid, phosphonic acid, hydroxy, lactam and lactone, N-substituted amide, N-substituted amino, carbamate, epoxy -, thiol, ether, alkoxy. Wear cyano groups or the like.
• the at least one acrylic monomer of the formula (I) is polymerized with at least one further comonomer which can likewise carry one or more of the functional and / or polar groups mentioned above.
• Moderate basic comonomers are e.g. N.N-dialkyl-substituted u amides.
• Examples include in particular NN-dimethylacrylamide, NN-dimethylmethacrylamide, N-tert-butylacrylamide, N-vinylpyrrolidone, N-vinyllactam, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, N-methylolacrylamide, N-methylolacrylamide, N-methylolacrylamide , N- (ethoxymethyl) acrylamide, N-isopropylacrylamide.
• vinyl esters, vinyl ethers, vinyl halides, vinylidene halides, vinyl compounds with aromatic cycles and heterocycles in the ⁇ -position are used as comonomers.
• Aromatic vinyl compounds such as styrene, are suitable as components, the aromatic nuclei preferably consisting of C 4 to C 18 and can also contain heteroatoms.
• Particularly preferred examples are 4-vinylpyridine, N-vinylphthalimide, methylstyrene, 3,4-dimethoxystyrene, 4-vinylbenzoic acid, benzyl acrylate, benzyl methacrylate, phenyl acrylate, phenyl methacrylate, t-butylphenyl acrylate, t-butylphenyl methacrylate, 4-biphenyl acrylate, 4-biphen 2-naphthyl acrylate, 2-naphthyl methacrylate and mixtures of these monomers, this list being not exhaustive.
• the oriented PSA according to the present invention can be produced by a process which comprises the following steps:
• Ri is hydrogen (H) or a methyl group (CH 3 ) and R 2 is hydrogen (H) or an unbranched or branched, saturated C to C 30 hydrocarbon radical which is optionally substituted by a functional group, (b) Coating the acrylic polymer from the melt to form a film, whereby the PSA is oriented, and (c) crosslinking the film by means of UV radiation.
• All of the monomers described above, to which further comonomers, also mentioned above, can optionally be added, can be used for the polymerization.
• the polymerization is preferably carried out in the presence of one of the crosslinkers mentioned above.
• radical polymerizations are advantageously carried out to prepare the poly (meth) acrylate PSAs.
• Initiator systems which additionally contain further radical initiators for the polymerization, in particular thermally decomposing radical-forming azo or peroxo initiators, are preferably used for the radical polymerizations.
• all of the usual initiators known to those skilled in the art for acrylates are suitable.
• the production of C-centered radicals is described in Houben Weyl, Methods of Organic Chemistry, Vol. E 19a, pp. 60 - 147. These methods are preferably used in analogy.
• radical sources are peroxides, hydroperoxides and azo compounds
• typical radical initiators are potassium peroxodisulfate, dibenzoyl peroxide, cumene hydroperoxide, cyclohexanone peroxide, di-butyl peroxide, azodiisonic acid butyronitrile, cyclohexyl peroxyl peroxetyl peroxetyl peroxetyl peroxetyl peroxetyl peroxetyl peroxetyl peroxetyl peroxetyl peroxetyl peroxetyl peroxetyl peroxyl peroxetyl peroxetyl peroxetyl peroxetyl peroxyl peroxetyl peroxetyl peroxetyl peroxetyl peroxyl peroxyl peroxyl peroxide tetraperyl peroxyl peroxyl peroxyl peroxyl peroxyl per
• photoinitiators with a copolymerizable double bond are used.
• Norrish I and II photoinitiators are suitable as photoinitiators. Examples are, for example, benzoin acrylate and an acrylated benzophenone from UCB (Ebecryl P 36 ® ).
• This list is not exhaustive.
• all photoinitiators known to the person skilled in the art can be copolymerized, which can crosslink the polymer via a radical mechanism under UV radiation.
• An overview of possible photoinitiators that can be functionalized with a double bond is given in Fouassier: "Photoinititation, Photopolymerization and Photocuring: Fundamentals and Applications", Hanser-Verlag, Kunststoff 1995.
• Carroy et al. In “Chemistry and Technology of UV and EB Formulation for Coatings, Inks and Paints ", Oldring (ed.), 1994, SITA, London.
• the average molecular weights M w of the PSAs formed in the radical polymerization are very preferably chosen such that they are in a range from 200,000 to 4,000,000 g / mol; PSAs with average molecular weights M w of 600,000 to 800,000 g / mol are produced especially for further use as hotmelt PSAs.
• the average molecular weight is determined using size exclusion chromatography (GPC) or matrix-assisted laser deionization / ionization mass spectrometry (MALDI-MS).
• the polymerization can be carried out in bulk, in the presence of one or more organic solvents, in the presence of water or in mixtures of organic solvents and water.
• Suitable organic solvents are pure alkanes (e.g. hexane, heptane, octane, isooctane), aromatic hydrocarbons (e.g. benzene, toluene, xylene), esters (e.g. ethyl acetate, propyl, butyl or hexyl acetate), halogenated hydrocarbons (e.g.
• Chlorobenzene Chlorobenzene
• alkanols eg methanol, ethanol, ethylene glycol, ethylene glycol monomethyl ether
• ethers eg diethyl ether, dibutyl ether
• a water-miscible or hydrophilic cosolvent can be added to the aqueous polymerization reactions to ensure that the reaction mixture is in the form of a homogeneous phase during the monomer conversion.
• Cosolvents which can be used advantageously for the present invention are selected from the following group consisting of aliphatic alcohols, glycols, ethers, glycol ethers, pyrrolidines, N-alkylpyrrolidinones, N-alkylpyrrolidones, polyethylene glycols, polypropylene glycols, amides, carboxylic acids and salts thereof, esters, Organosulfides, sulfoxides, sulfones, alcohol derivatives, hydroxyether derivatives, amino alcohols, ketones and the like, as well as derivatives and mixtures thereof.
• the polymerization time is between 4 and 72 hours.
• the entry of heat is essential for the thermally decomposing initiators.
• the polymerization can be initiated for the thermally decomposing initiators by heating to 50 to 160 ° C., depending on the type of initiator.
• polyacrylate PSAs Another advantageous production process for the polyacrylate PSAs is anionic polymerization.
• Inert solvents are preferably used as the reaction medium, e.g. aliphatic and cycloaliphatic hydrocarbons, or also aromatic hydrocarbons.
• the living polymer is generally represented by the structure P L (A) -Me, where Me is a Group I metal, such as lithium, sodium or potassium, and P L (A) is a growing polymer block from the monomers A. is.
• the molar mass of the polymer to be produced is controlled by the ratio of the initiator concentration to the monomer concentration.
• Suitable polymerization initiators are, for. B. n-propyllithium, n-butyllithium, sec-butyllithium, 2-naphthyllithium, cyclohexyllithium or octyllithium, this list does not claim to be complete.
• Initiators based on samarium complexes for the polymerization of acrylates are also known (Macromolecules, 1995, 28, 7886) and can be used here.
• difunctional initiators can also be used, such as, for example, l. L ⁇ - tetraphenyM ⁇ -dilithiobutane or 1,1,4,4-tetraphenyl-1,4-dilithioisobutane.
• Coinitiators can also be used. Suitable coinitiators include lithium halides, alkali metal alkoxides or alkyl aluminum compounds.
• the ligands and coinitiators are chosen so that acrylate monomers such as e.g. n-Butyl acrylate and 2-ethylhexyl acrylate can be polymerized directly and do not have to be generated in the polymer by transesterification with the corresponding alcohol.
• Controlled radical polymerization methods are also suitable for the production of polyacrylate PSAs with a narrow molecular weight distribution.
• a control reagent of the general formula is then preferably used for the polymerization:
• R and R 1 are selected independently of one another or are identical and are selected from the group comprising the following radicals: - branched and unbranched Ci to -C 8 alkyl radicals; C 3 - to C ⁇ 8 alkenyl radicals; C 3 to C 18 alkynyl radicals; - C to Ci ⁇ -Alkxoyreste; - C 1 to C 8 alkyl radicals substituted by at least one OH group or a halogen atom or a silyl ether; C 3 to C 18 alkenyl radicals; C 3 to d ⁇ alkynyl radicals; - C 2 -C 8 hetero-alkyl radicals with at least one O atom and / or one NR * group in the carbon chain, where R * can be any (in particular organic) radical; - With at least one ester group, amine group, carbonate group, cyano group, isocyano group and / or epoxy group and / or sulfur-substituted C Cia-
• Control reagents of type (I) preferably consist of the following further restricted compounds, the list below serving only as examples for the respective connecting groups and not being exhaustive: - Halogen atoms are preferably F, CI, Br or I, more preferably CI and Br. Both linear and branched chains are outstandingly suitable as alkyl, alkenyl and alkynyl radicals in the various substituents.
• alkyl radicals which contain 1 to 18 carbon atoms are methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, 2-pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, t-octyl, nonyl , Decyl, undecyl, tridecyl, tetradecyl, hexadecyl and octadecyl.
• alkenyl radicals having 3 to 18 carbon atoms are propenyl, 2-butenyl, 3-butenyl, isobutenyl, n-2,4-pentadienyl, 3-methyl-2-butenyl, n-2-octenyl, n-2-dodecenyl, Isododecenyl and oleyl.
• alkynyl having 3 to 18 carbon atoms are propynyl, 2-butynyl, 3-butynyl, n-2-octynyl and n-2-octadecynyl.
• hydroxy-substituted alkyl radicals are hydroxypropyl, hydroxybutyl or hydroxyhexyl.
• halogen-substituted alkyl radicals are dichlorobutyl, monobromobutyl or trichlorohexyl.
• a suitable C2-C18 heteroalkyl radical with at least one O atom in the carbon chain is, for example, -CH2-CH2-0-CH2-CH3.
• C3-C12 cycloalkyl radicals for example, cyclopropyl, cyclopentyl, cyclohexyl or trimethylcyclohexyl are used.
• aryl radicals are, for example, phenyl, naphthyl, benzyl, 4-tert-butylbenzyl or other substituted phenyl, such as, for example, ethyl, toluene, xylene, mesitylene, isopropylbenzene, dichlorobenzene or bramotoluene.
• R 2 can also be selected independently of R and R 1 from the group listed above for these radicals.
• polymerization is usually carried out only to a low degree (WO 98/01478 AI) in order to achieve the narrowest possible molecular weight distributions. Due to the low sales, these polymers cannot be used as PSAs and especially not as hotmelt PSAs, since the high proportion of residual monomers negatively influences the adhesive properties, the residual monomers contaminate the recycled solvent in the concentration process, and the corresponding self-adhesive tapes have a very high outgassing behavior would show. To avoid this disadvantage of low sales, the polymerization is initiated several times in a particularly preferred procedure.
• Nitroxide-controlled polymerizations can be carried out as a further controlled radical polymerization method.
• nitroxides of type (Va) or (Vb) are used in a favorable procedure:
• Halides e.g. Chlorine, bromine or iodine
• PROXYL 2,2,5,5-TetramethyM-pyrrolidinyloxyl
• PROXYL 3-carbamoyl-PROXYL, 2,2-dimethyl-4,5-cyclohexyl-PROXYL, 3-oxo-PROXYL, 3-hydroxylimine-PROXYL, 3- Aminomethyl-PROXYL, 3-methoxy-PROXYL, 3-t-butyl-PROXYL, 3,4-di-t-butyl-P ROXYL;
• TEMPO 2,2,6,6-tetramethyl-l-piperidinyloxy pyrrolidinyloxyl
• 4-benzoyloxy-TEMPO 4-methoxy-TEMPO
• 4-chloro-TEMPO 4-hydroxy-TEMPO
• 4-oxo-TEMPO 4 -Amino-TEMPO, 2,2,6,6, -Tetraethyl-l-piperidinyloxyl, 2.2 1 6-trimethyl-6-ethyl-1-pi perid i nyloxyl;
• No. 4,581,429 A discloses a controlled radical polymerization process which uses an initiator of a compound of the formula R'R "N-0-Y, in which Y is a free radical species which can polymerize unsaturated monomers.
• the reactions generally have low conversions
• WO 98/13392 A1 describes open-chain alkoxyamine compounds which have a symmetrical substitution pattern.
• EP 735 052 A1 discloses a process for producing thermoplastic elastomers with narrow molar mass distributions.
• WO 96/24620 A1 describes a polymerization process in which very special radical compounds, such as, for example, phosphorus-containing nitroxides based on imidazolidine, are used
• WO 98/44008 A1 discloses special Nrtroxyls based on morpholines, piperazinones and piperazinediones DE 199 49 352 A1 describes heterocyclic Al koxyamines as regulators in controlled radical polymerizations.
• Corresponding further developments of the alkoxyamines and the corresponding free nitroxides improve the efficiency for the production of polyacrylates (Hawker, contribution to the General Meeting of the American Chemical Society, spring 1997; Husemann, contribution to the IUPAC World-Polymer Meeting 1998, Gold Coast).
• ATRP atom transfer radical polymerization
• the polyacrylate PSAs preferably monofunctional or difunctional secondary or tertiary halides as initiators and for the abstraction of the (r) halide (s) Cu, Ni, , Fe, Pd, Pt, Ru, Os, Rh, Co, Ir, Ag or Au complexes
• the different possibilities of the ATRP are also described in the documents US 5,945,491 A, US 5,854,364 A and US 5,789,487 A.
• Resins can be added to the polyacrylate PSAs for further development. All of the previously known adhesive resins described in the literature can be used as tackifying resins to be added. Representative are the pinene, indene and rosin resins, their disproportionated, hydrogenated, polymerized, esterified derivatives and salts, the aliphatic and aromatic hydrocarbon resins, terpene resins and terpene phenolic resins as well as C5, C9 and other hydrocarbon resins. Any combination of these and other resins can be used to adjust the properties of the resulting adhesive as desired.
• all (soluble) resins compatible with the corresponding polyacrylate can be used, in particular reference is made to all aliphatic, aromatic, alkylaromatic hydrocarbon resins, hydrocarbon resins based on pure monomers, hydrogenated hydrocarbon resins, functional hydrocarbon resins and natural resins. Attention is drawn to the presentation of the state of knowledge in the "Handbook of Pressure Sensitive Adhesive Technology" by Donatas Satas (van Nostrand, 1989).
• Plasticizers plasticizers
• fillers e.g. fibers, carbon black, zinc oxide, titanium dioxide, chalk, solid or hollow glass spheres, microspheres made of other materials, silicic acid, silicates
• nucleating agents e.g. in the form of primary and secondary antioxidants or in the form of light stabilizers.
• Crosslinkers and promoters can also be added for crosslinking.
• Suitable crosslinkers for UV crosslinking are, for example, bi- or multifunctional acrylates and methacrylates.
• UV-absorbing photoinitiators are advantageously added to the polyacrylate PSAs.
• Useful photoinitiators that are very easy to use are benzoin ethers, such as. As benzoin methyl ether and benzoin isopropyl ether, substituted acetophenones, such as. B. 2,2-diethoxyacetophenone (available as Irgacure 651 ® from Ciba Geigy ® ), 2,2-dimethoxy-2-phenyl-1-phenylethanone, dimethoxyhydroxyacetophenone, substituted ⁇ -ketols, such as. B. 2-methoxy-2-hydroxypropiophenone, aromatic sulfonyl chlorides, such as.
• the above-mentioned and other usable photoinitiators and others of the Norrish I or Norrish II type may contain the following radicals: benzophenone, aceto-phenone, benzil, benzoin, hydroxyalkylphenone, phenylcyclohexylketone, anthraquinone, trimethylbenzoylphosphine oxide, methylthiophenylmorphol , Aminoketone, azobenzoin, thioxanthone, hexarylbisimidazole, triazine or fluorenone, where each of these radicals can additionally be substituted by one or more halogen atoms and / or one or more alkyloxy groups and / or one or more amino groups or
• the polymers described above are preferably coated as hot-melt systems. It may therefore be necessary for the manufacturing process to remove the solvent from the PSA.
• a very preferred method is the concentration via a single or twin screw extruder.
• the twin screw extruder can be operated in the same or opposite directions.
• the solvent or water is preferably distilled off over several vacuum stages. In addition, depending on the distillation temperature of the solvent, counter-heating is carried out.
• the residual solvent proportions are preferably ⁇ 1%, more preferably ⁇ 0.5% and very preferably ⁇ 0.2%.
• the hot melt is processed from the melt.
• the orientation within the PSA is generated by the coating process.
• Different coating processes can be used for coating as a hot melt and thus also for orientation.
• the polyacrylate PSAs are coated using a roll coating process and the orientation is produced by stretching. Different roller coating processes are described in the "Handbook of Pressure Sensitive Adhesive Technology" by Donatas Satas (van Nostrand, New York 1989).
• orientation is achieved by coating via a melting nozzle.
• the orientation of the PSA can be generated here on the one hand by the nozzle design within the coating nozzle, or on the other hand by a stretching process after the nozzle emerges.
• the orientation is freely adjustable.
• the stretching ratio can be controlled, for example, by the width of the die gap. Stretching always occurs when the layer thickness of the pressure-sensitive adhesive film on the carrier material to be coated is less than the width of the nozzle gap.
• the orientation is achieved by the extrusion coating.
• the extrusion coating is preferably carried out with an extrusion die.
• the extrusion nozzles used can come from one of the following three categories: T nozzle, fish tail nozzle and ironing nozzle. The individual types differ in the shape of their flow channel.
• the shape of the extrusion die can also be used to generate an orientation within the hotmelt PSA.
• orientation can also be achieved after stretching out the nozzle by stretching the PSA film.
• an ironing nozzle on a carrier, in such a way that a polymer layer is formed on the carrier by a relative movement from nozzle to carrier.
• crosslinking takes place less than 60 minutes after coating, in a more preferred version it takes less than 3 minutes. In an extremely preferred design, the crosslinking takes place in the in-line process less than 5 seconds after the coating.
• coating is carried out directly on a carrier material.
• a carrier material In principle, all materials known to the person skilled in the art, such as, for example, BOPP, PET, nonwoven, PVC, foam or release papers (glassine, HDPE, LDPE) are suitable as carrier material. The best orientation effects are achieved by placing them on a cold surface. Therefore, the carrier material should be cooled directly by a roller during the coating.
• the roller can be cooled by a liquid film / contact film from the outside or from the inside or by a cooling gas.
• the cooling gas can also be used to cool the PSA emerging from the coating nozzle.
• the roller is wetted with a contact medium, which is then located between the roller and the carrier material.
• both a melting die and an extrusion die can be used for this process.
• the roller is cooled to room temperature, in an extremely preferred embodiment to temperatures below 10 ° C. The roller should rotate in the meantime.
• the roller is also used to crosslink the oriented PSA.
• UV crosslinking short-term ultraviolet radiation in a wavelength range from 200 to 400 nm is used, depending on the UV photoinitiator used. irradiated, in particular using high-pressure or medium-pressure mercury lamps with a power of 80 to 240 W / cm.
• the radiation intensity is adapted to the respective quantum yield of the UV photoinitiator, the degree of crosslinking to be set and the setting of the degree of orientation.
• Typical radiation devices that can be used are linear cathode systems, scanner systems or segment cathode systems if they are electron beam accelerators.
• the typical acceleration voltages are in the range between 50 kV and 500 kV, preferably 80 kV and 300 kV.
• the spreading doses used range between 5 and 150 kGy, in particular between 20 and 100 kGy.
• the oriented PSA is coated on a roller provided with a contact medium.
• the contact medium can in turn cool the PSA very quickly.
• a material can be used as the contact medium, which is able to make contact between the PSA and the roller surface, in particular a material that fills the voids between the carrier material and the roller surface (for example, unevenness in the roller surface, bubbles).
• a rotating cooling roller is coated with a contact medium.
• a liquid, such as water, is chosen as the contact medium.
• alkyl alcohols such as ethanol, propanol, butanol, hexanol are suitable as additives, without wishing to restrict the choice of alcohols by these examples.
• Long-chain alcohols, polyglycols, ketones, amines, carboxylates, sulfonates and the like are also very advantageous. Many of these compounds lower the surface tension or increase the conductivity.
• a reduction in the surface tension can also be achieved by adding small amounts of nonionic and / or anionic and / or cationic surfactants to the contact medium.
• commercial detergents or soap solutions can be used for this, preferably in a concentration of a few g / l in water as the contact medium.
• Special surfactants which can also be used at low concentrations, are particularly suitable. Examples include sulfonium surfactants (e.g. ⁇ -di (hydroxyalkyl) sulfonium salt), furthermore, for example, ethoxylated nonylphenylsulfonic acid ammonium salts or block copolymers, especially diblocks.
• surfactants in Ullmann's Encyclopedia of Industrial Chemistry, Sixth Edition, 2000 Electronic Release, Wiley-VCH, Weinheim 2000.
• the aforementioned liquids can also be used as contact media without the addition of water, either individually or in combination with one another.
• the contact medium for example to increase the shear resistance, reduce the transfer of surfactants or the like to the liner surface and thus improve cleaning options for the end product
• salts, gels and similar viscosity-increasing additives can advantageously be added to the contact medium and / or the additives used
• the roller can be macroscopically smooth or have a slightly structured surface. It has proven useful if it has a surface structure, in particular a roughening of the surface. This can improve the wetting of the contact medium.
• the process runs particularly well if the roll can be tempered, preferably in a range from -30 ° C. to 200 ° C., very particularly preferably from 5 ° C. to 25 ° C.
• the contact medium is preferably applied to the roller, but it is also possible for it to be applied without contact, for example by spraying.
• the roller is usually covered with a protective layer. This is preferably selected so that it is well wetted by the contact medium. Generally the surface is conductive. However, it can also be cheaper to coat them with one or more layers of insulating or semiconducting material.
• a second roller advantageously with a wettable or absorbent surface, runs through a bath with the contact medium, is wetted or soaked with the contact medium and is in contact with the roller Apply or spread film of this contact medium.
• the oriented pressure-sensitive adhesive is preferably immediately crosslinked on the cooling roll provided with the contact medium and then transferred to the backing material.
• the degree of orientation within the acrylic PSAs depends on the coating process.
• the orientation can e.g. can be controlled by the nozzle and coating temperature and by the molecular weight of the polyacrylate PSA.
• the degree of orientation is freely adjustable through the width of the nozzle gap. The thicker that
• the radiation intensity of the UV radiation also serves as a setting parameter for the degree of orientation.
• the degree of orientation can be reduced by increasing the UV dose.
• the radiation intensity thus serves to vary the degree of crosslinking, the adhesive properties and to control the anisotropic behavior.
• the orientation of the adhesive can be measured with a polarimeter, with infrared dichroism or with X-ray scattering. It is known that the orientation in acrylic PSAs in the uncrosslinked state is only retained for a few days. The system relaxes during rest or storage and loses its preferred direction. This effect can be significantly suppressed by crosslinking after coating. The relaxation of the oriented polymer chains converges to zero, and the oriented PSAs can be stored for a very long time without losing their preferred direction.
• measuring the shrinkback in the free film is also suitable for determining the orientation and the anisotropic properties of the PSA.
• orientation can also be generated after the coating.
• a stretchable carrier material is then preferably used here, in which case the PSA is also stretched when expanded.
• acrylic PSAs conventionally coated from solution or water can also be used.
• this stretched PSA is in turn crosslinked with UV radiation.
• the content of the invention is the use of such oriented PSAs for PSA tapes coated on one or both sides.
• a 20 mm wide strip of an acrylic PSA coated on a polyester or siliconized release paper was applied to steel plates. Depending on the direction and stretching, longitudinal or transverse patterns were glued to the steel plate.
• the PSA strip was pressed onto the substrate twice with a 2 kg weight.
• the adhesive tape was then immediately removed from the substrate at 30 mm / min and at a 180 ° angle.
• the steel plates were washed twice with acetone and once with isopropanol.
• the measurement results were averaged from three measurements and are given in N / cm. All measurements were carried out at room temperature under air-conditioned conditions. ⁇ ssunfl der D p.Rejbruchu Version 1
• a spectrophotometer model Uvikon 910 was provided with two crossed polaroid filters in the sample beam.
• Oriented acrylates were fixed between two object carriers.
• the layer thickness of the oriented sample was determined from preliminary tests using a thickness probe.
• the sample prepared in this way was placed in the measuring beam of the spectrophotometer in such a way that its orientation direction deviated by 45 ° from the optical axes of the two polaroid filters.
• the transmission T was then tracked over time using a time-resolved measurement.
• the coated and oriented PSAs were stored over a longer period of time as a rag sample and then analyzed.
• the average molecular weight M w and the polydispersity PD were determined by gel permeation chromatography. THF with 0.1% by volume of trifluoroacetic acid was used as the eluent. The measurement was carried out at 25 ° C. PSS-SDV, 5 ⁇ , 10 3 A, ID 8.0 mm ⁇ 50 mm was used as guard column. The columns PSS-SDV, 5 ⁇ , 10 3 as well as 10 5 and 10 6 ⁇ , each with ID 8.0 mm x 300 mm, were used for the separation. The sample concentration was 4 g / l and the flow rate was 1.0 ml per minute. It was measured against PMMA standards.
• the manufacturing processes described below differ essentially in the solvent mixtures used.
• the polymerization was carried out in particular in a mixture of acetone and isopropanol with an increasing proportion of isopropanol from Example 1 to Example 4.
• a conventional 10 L reactor for radical polymerizations was charged with 60 g of acrylic acid, 1800 g of 2-ethylhexyl acrylate, 20 g of maleic anhydride, 120 g of N-isopropyl acrylamide and 666 g of acetone / isopropanol (98/2). After 45 minutes of passage The reactor was heated to 58 ° C. by nitrogen gas with stirring and 0.6 g of 2,2'-azoisobutyronitrile (AIBN) dissolved in 20 g of acetone was added. The outer heating bath was then heated to 70 ° C. and the reaction was carried out constantly at this outside temperature. After 45 minutes of reaction time 0.2 g of Vazo 52 was added dissolved ® from.
• AIBN 2,2'-azoisobutyronitrile
• DuPont in 10 g of acetone After a reaction time of 70 minutes, 0.2 g of Vazo 52 ® from DuPont dissolved in 10 g acetone were added, after 85 minutes reaction time 0.4 g Vazo 52 ® from DuPont dissolved in 400 g acetone / isopropanol (98/2 ). After 1:45 h, 400 g of acetone / isopropanol (98/2) were added. After 2 hours, 1.2 g of 2,2'-azoisobutyronitrile (AIBN) dissolved in 20 g of acetone were added.
• AIBN 2,2'-azoisobutyronitrile
• Acrylic acid 1800 g 2-ethyl hexyl acrylate, 20 g maleic anhydride, 120 g N-isopropyl acrylamide and 666 g acetone / isopropanol (97/3) filled.
• the reactor was heated to 58 ° C. and 0.6 g of 2,2'-azoisobutyronitrile (AIBN) dissolved in 20 g of acetone were added.
• the outer heating bath was then heated to 70 ° C. and the reaction was carried out constantly at this outside temperature.
• 0.2 g of Vazo 52 was added dissolved ® from. DuPont in 10 g of acetone.
• a conventional 10 L reactor for radical polymerizations was charged with 60 g of acrylic acid, 1800 g of 2-ethylhexyl acrylate, 20 g of maleic anhydride, 120 g of N-isopropylacrylamide and 666 g of acetone / isopropanol (95/5). After nitrogen gas had been passed through for 45 minutes with stirring, the reactor was heated to 58 ° C. and 0.6 g of 2 l of 2'-azoisobutyronitrile (AIBN) dissolved in 20 g of acetone were added. The outer heating bath was then heated to 70 ° C. and the reaction was carried out constantly at this outside temperature. After 45 minutes of reaction time 0.2 g of Vazo 52 was added dissolved ® from.
• AIBN 2'-azoisobutyronitrile
• DuPont in 10 g of acetone After a reaction time of 70 min, 0.2 g of Vazo 52 ® from DuPont dissolved in 10 g acetone were added, after 85 min reaction time 0.4 g Vazo 52 ® from DuPont dissolved in 400 g acetone / isopropanol (95/5 ). After 2 h, 1.2 g of 2,2'-azoisobutyronitrile (AIBN) dissolved in 400 g of acetone / isopropanol (95/5) were added. After a reaction time of 4 h, the mixture was diluted with 400 g of acetone / isopropanol (95/5).
• AIBN 2,2'-azoisobutyronitrile
• a conventional 10 L reactor for radical polymerizations was charged with 60 g of acrylic acid, 1800 g of 2-ethylhexyl acrylate, 20 g of maleic anhydride, 120 g of N-isopropylacrylamide and 666 g of acetone / isopropanol (93/7). After nitrogen gas had been passed through for 45 minutes with stirring, the reactor was heated to 58 ° C. and 0.6 g of 2,2'-azoisobutyronitrile (AIBN) dissolved in 20 g of acetone were added. The external heating bath was then heated to 70 ° C. and the reaction was carried out constantly at this external temperature. After 45 minutes of reaction time 0.2 g of Vazo 52 was added dissolved ® from.
• AIBN 2,2'-azoisobutyronitrile
• DuPont in 10 g of acetone After a reaction time of 70 minutes, 0.2 g of Vazo 52 ® from DuPont dissolved in 10 g acetone were added, after 85 minutes reaction time 0.4 g Vazo 52 ® from DuPont dissolved in 400 g acetone / isopropanol (93/7 ). After 2 h, 1.2 g of 2 1 2'-azoisobutyronitrile (AIBN) dissolved in 20 g of acetone were added. After 2:10 h with 400 g Diluted acetone isopropanol (93/7).
• AIBN 2 1 2'-azoisobutyronitrile
• the polymers prepared according to the above examples were freed from the solvent in a vacuum drying cabinet. A 10 ton vacuum was applied and slowly heated to 100 ° C. The hot melt pressure sensitive adhesive was then coated using a Pröls melt nozzle. The coating temperature was 160 ° C. It was coated at 20 m / min on a siliconized release paper from Laufenberg. The width of the nozzle gap was 200 ⁇ m. After coating, the mass application of the PSA on the release paper was 50 g / m 2 . A pressure of 6 bar was applied to the melt nozzle for coating so that the hotmelt PSA could be pressed through the nozzle.
• UV crosslinking was carried out 15 minutes after coating at room temperature.
• a UV crosslinking system from Eltosch was used for UV crosslinking.
• a medium-pressure mercury lamp with an intensity of 120 W / cm 2 was used as the UV lamp.
• the web speed was 20 m / min and it was cross-linked with full radiation.
• the PSA tapes were subjected to a variable number of radiation passes.
• the UV dose increases linearly with the number of passes.
• the UV doses were determined with the Power-Puck ® from Eltosch. For example, a UV dose of 0.8 J / cm 2 was measured for 2 passes, 1.6 J / cm 2 for 4 passes, 3.1 J / cm 2 for 8 passes and 3 for 10 passes, 8 J / cm 2 .
• the acrylate PSAs according to Examples 1 to 4 were freed from the solvent and processed from the melt. It was coated using a melting nozzle at 160 ° C. and coated on a release paper left at room temperature. All adhesives could be processed in the hotmelt process with regard to temperature stability and flow viscosity. After 15 minutes, crosslinking was carried out using various UV doses. To determine the anisotropic properties (orientation), the shrinkback in the free film was first measured according to test D. To determine the degree of crosslinking, test C was carried out and the gel content was thus determined. The gel fraction indicates the percentage of the crosslinked polymer. The results are summarized in Table 2.
• the difference ⁇ n between the refractive index n MD measured in a preferred direction (stretching direction, machine direction MD) and the refractive index ⁇ CD measured in a direction perpendicular to the preferred direction (cross direction CD) serves as a measure of the orientation of the PSA.
• ie ⁇ n ⁇ * D - " CD - This value is accessible through the measurements described in test B. All examples showed an orientation of the polymer chains.
• the ⁇ n values determined are listed in Table 5.
• the orientation within the acrylic PSAs could be verified by the birefringence measurement for the measured samples.
• a pressure-sensitive adhesive tape By applying a pressure-sensitive adhesive tape to a curved surface with subsequent heating, the pressure-sensitive adhesive tape contracts and thus adjusts to the curvature of the substrate. In this way, the bonding is made significantly easier and the number of air pockets between the substrate and the adhesive tape is significantly reduced.
• the PSA can have the best effect. This effect can be supported by an oriented carrier material. After application, both the carrier material and the oriented PSA shrink under heating, so that the bonds on the curvature are completely free of tension.
• the PSAs of the invention also offer a wide range for applications which take advantage of the low elongation in the longitudinal direction and the possibility of shrinkback in an advantageous manner.
• pre-stretching the PSAs can also be used extremely well.
• Another exemplary application for such highly oriented acrylic PSAs is stripable double-sided adhesive bonds.
• the oriented PSA has already been pre-stretched by several 100%, so that to remove the double-sided adhesive, the acrylic PSA only has to be stretched a few percent in the stretching direction (MD).
• MD stretching direction
• these products are produced as acrylate hotmelts with a layer thickness of several 100 ⁇ m. Pure acrylates are used in a particularly preferred manner.
• the oriented acrylic strips are transparent, age-stable and inexpensive to manufacture.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Adhesive Tapes (AREA)
• Adhesives Or Adhesive Processes (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

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• 2004
  • 2004-01-16 DE DE102004002279A patent/DE102004002279A1/de not_active Withdrawn
• 2005
  • 2005-01-04 AU AU2005205192A patent/AU2005205192A1/en not_active Abandoned
  • 2005-01-04 JP JP2006548294A patent/JP2007518855A/ja active Pending
  • 2005-01-04 CN CNA2005800025968A patent/CN1910247A/zh active Pending
  • 2005-01-04 WO PCT/EP2005/050021 patent/WO2005068575A1/de active Application Filing
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