Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/0053—Details of the reactor
  • B01J19/0066—Stirrers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/18—Stationary reactors having moving elements inside
  • B01J19/1812—Tubular reactors
  • B01J19/1818—Tubular reactors in series
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/18—Stationary reactors having moving elements inside
  • B01J19/20—Stationary reactors having moving elements inside in the form of helices, e.g. screw reactors
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J4/00—Feed or outlet devices; Feed or outlet control devices
  • B01J4/02—Feed or outlet devices; Feed or outlet control devices for feeding measured, i.e. prescribed quantities of reagents
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/07—Flat, e.g. panels
  • B29C48/08—Flat, e.g. panels flexible, e.g. films
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
  • B29C48/40—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders
  • B29C48/435—Sub-screws
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
  • B29C48/40—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders
  • B29C48/435—Sub-screws
  • B29C48/44—Planetary screws
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F2/00—Processes of polymerisation
  • C08F2/02—Polymerisation in bulk
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F2/00—Processes of polymerisation
  • C08F2/04—Polymerisation in solution
  • C08F2/06—Organic solvent
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F20/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride, ester, amide, imide or nitrile thereof
  • C08F20/02—Monocarboxylic acids having less than ten carbon atoms, Derivatives thereof
  • C08F20/10—Esters
  • C08F20/12—Esters of monohydric alcohols or phenols
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/10—Esters
  • C08F220/12—Esters of monohydric alcohols or phenols
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D133/00—Coating compositions 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; Coating compositions based on derivatives of such polymers
  • C09D133/04—Homopolymers or copolymers of esters
  • C09D133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
  • C09D133/062—Copolymers with monomers not covered by C09D133/06
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D133/00—Coating compositions 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; Coating compositions based on derivatives of such polymers
  • C09D133/04—Homopolymers or copolymers of esters
  • C09D133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
  • C09D133/062—Copolymers with monomers not covered by C09D133/06
  • C09D133/066—Copolymers with monomers not covered by C09D133/06 containing -OH groups
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00049—Controlling or regulating processes
  • B01J2219/00051—Controlling the temperature
  • B01J2219/00074—Controlling the temperature by indirect heating or cooling employing heat exchange fluids
  • B01J2219/00087—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with heat exchange elements outside the reactor
  • B01J2219/00094—Jackets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00049—Controlling or regulating processes
  • B01J2219/00051—Controlling the temperature
  • B01J2219/00132—Controlling the temperature using electric heating or cooling elements
  • B01J2219/00135—Electric resistance heaters
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00049—Controlling or regulating processes
  • B01J2219/00186—Controlling or regulating processes controlling the composition of the reactive mixture
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/18—Details relating to the spatial orientation of the reactor
  • B01J2219/182—Details relating to the spatial orientation of the reactor horizontal
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/50—Details of extruders
  • B29C48/76—Venting, drying means; Degassing means
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
  • C08L33/04—Homopolymers or copolymers of esters
  • C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/582—Recycling of unreacted starting or intermediate materials
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S526/00—Synthetic resins or natural rubbers -- part of the class 520 series
  • Y10S526/918—Polymerization reactors for addition polymer preparation

Definitions

• the invention relates to a polyacrylate pressure-sensitive adhesive, to methods for producing a pressure-sensitive adhesive of this kind, and to the use of pressure-sensitive adhesives of this kind.
• polyacrylate pressure-sensitive adhesives For industrial pressure-sensitive adhesive tape applications it is very common to use polyacrylate pressure-sensitive adhesives.
• Polyacrylates possess a variety of advantages over other elastomers. They are very stable toward UV light, oxygen, and ozone. Synthetic and natural rubber adhesives generally contain double bonds, which render these adhesives unstable to the aforementioned environmental effects.
• a further advantage of polyacrylates is their transparency and their usefulness across a relatively wide temperature range.
• Polyacrylate pressure-sensitive adhesives are generally prepared in solution by means of a free-radical polymerization.
• the polyacrylates are, generally speaking, coated from solution onto the corresponding carrier material, via a coating bar, and subsequently dried. To increase the cohesion the polymer is crosslinked. Curing proceeds thermally or by UV crosslinking or by EB curing (EB: electron beams).
• EB electron beams
• the pressure-sensitive adhesive is applied from the melt to the carrier material.
• PSA pressure-sensitive adhesive
• This new technology also entails restrictions.
• the solvent Prior to coating, the solvent is removed from the PSA, which additionally is prepared in solution, in a drying extruder.
• the drying operation is associated with a relatively high temperature and shearing exposure, so that high molecular weight polyacrylate PSAs in particular are significantly damaged.
• the acrylate PSA undergoes gelling or the low molecular weight fraction is sharply enriched as a result of molecular weight reduction. Both effects are unwanted, since they are deleterious for the application. Either the adhesive can no longer be coated, or its technical adhesive properties are altered.
• polyacrylate adhesives having a low average molecular weight and a narrow molecular weight distribution.
• the fraction of low molecular weight and high molecular weight molecules in the polymer is sharply reduced as a result of the polymerization process.
• the disappearance of the high molecular weight fractions lowers the flow viscosity, and the composition shows less of a tendency to gel.
• the low molecular weight fraction there is a reduction in the number of oligomers, which reduce the shear strength of the PSA.
• a further controlled polymerization method used is that of atom transfer radical polymerization, ATRP.
• ATRP atom transfer radical polymerization
• the various possibilities of ATRP are described in U.S. Pat. No. 5,945,491 A, U.S. Pat. No. 5,854,364 A and U.S. Pat. No. 5,789,48 A.
• metal catalysts are used, a side-effect of which is a negative influence on the aging of the PSAs (gelling, transesterification).
• the majority of metal catalysts are toxic, discolor the adhesive, and can be removed from the polymer only by means of costly and inconvenient precipitations.
• U.S. Pat. No. 4,581,429 A discloses a controlled free-radical polymerization process.
• the process employs as its initiator a compound of the formula R′R′′N—O—X, in which X represents a free radical species which is able to polymerize unsaturated monomers.
• X represents a free radical species which is able to polymerize unsaturated monomers.
• the conversion rates of the reactions are generally low.
• a particular problem is the polymerization of acrylates, which proceeds only at very low yields and molecular weights.
• WO 96/24620 A, WO 98/30601 A, and WO 98/4408 A describe further polymerization methods in which regulating substances are used to prepare polymers having low polydispersities. Disadvantages of these methods include the low conversion and the use of solvents.
• RAFT Reversible Addition-Fragmentation Chain Transfer
• the process is described at length in WO 98/01478 A and WO 99/31144 A, but in the manner depicted therein is not suitable for the production of PSAs, since the conversions achieved are very low and the average molecular weight of the polymers produced is too low for acrylate PSAs. Hence the polymers described cannot be used as acrylate PSAs.
• An improvement is achieved with the process described in DE 100 30 217 A.
• the invention accordingly provides a method for producing a UV-crosslinkable solvent-free polyacrylate pressure-sensitive adhesive which possesses an average molecular weight M w (weight average) of 100 000 to 3 000 000 g/mol and also possesses copolymerized photoinitiator units.
• the polyacrylate PSAs are produced by way of a free-radical solvent-free polymerization operation.
• the polyacrylate PSA has an average molecular weight M w (weight average) of 100 000 to 800 000 g/mol and a polydispersity of not more than 4.0 and also possesses these copolymerized photoinitiator units.
• the production of the polyacrylate PSAs having a polydispersity of not more than 4.0 is accomplished by way of a free-radical solvent-free polymerization operation in a planetary roller extruder in which a polymer is prepared from a monomer mixture, the monomer mixture for polymerization comprising copolymerizable photoinitiators and the polymerization operation being regulated in particular by the presence of at least one chemical compound containing the unit as polymerization regulator, X being S, O or N.
• Polymerization regulators which can be used with great advantage for the purposes of the invention include trithiocarbonates or dithioesters.
• the present invention therefore relates, among other things, to a method for producing solvent-free UV-crosslinkable polyacrylate pressure-sensitive adhesives.
• the method is also notable for the fact that the preparation of the polymer takes place by means of solvent-free polymerization, the monomer mixture possessing copolymerizable photoinitiators.
• copolymerizable photoinitiators during the solvent-free polymerization produces a polymer which can be very efficiently crosslinked by UV radiation.
• the polymers prepared by such a method coat very well and are notable not only for the high UV crosslinking efficiency but also for their extremely low odor intensity. They are suitable, consequently, for producing adhesive tapes which can be used even under high shearing load.
• An adhesive tape coated with the adhesive of the invention possesses, moreover, no solvent residues, as is the case with adhesive tapes produced by the conventional method.
• Commercially available UV-crosslinkable acrylate hotmelt PSAs for example, still include a certain residual solvent fraction.
• the planetary roller extruder is suitable in particular by virtue of its outstanding thermal characteristics and also by virtue of the extraordinarily diverse possibilities of temperature control for this solvent-free polymerization.
• the extruder used is preferably operated continuously. Partial recycling of the product stream, referred to as loop operation, may also be advantageous. The most advantageous is to produce a solvent-free UV-crosslinkable polyacrylate PSA in a hydraulically filled planetary roller extruder. Hydraulic filling simplifies the observance of oxygen-free conditions and also the best-possible utilization of the extruder section. Moreover, phase boundaries are avoided, which can have disruptive consequences for the polymerization operation.
• the monomers can be metered to the polymerization reactor either individually or as a mixture.
• Preliminary mixing, particularly of the copolymerizable photoinitiator, ensures a uniform distribution of the reaction mixture.
• the polymer following polymerization in the planetary roller extruder, is removed from constituents which are still volatile, such as unreacted monomers, in a devolatilizing extruder. These constituents, after a determination of their composition, may be fed back to the starting-material stream.
• the polymer following polymerization and, where necessary, devolatilizing and, where appropriate, the addition of one or more of the additives—which addition may take place in the polymerization extruder and/or in a downstream compounding extruder—is coated from the melt, advantageously gel-free, onto a carrier
• gel-free denotes compliance with the requirements for coatability of the compositions using the coating apparatus which is commonly employed and which is familiar to the skilled worker for these purposes; in particular, for a coatability which is distinguished by a uniform (homogeneous) coating pattern with no inhomogeneities or streaks when coating takes place through the commonly used coating nozzles or by means of a roll applicator).
• UV-crosslinking polyacrylate PSA and the narrow-distribution, UV-crosslinking polyacrylate PSA are composed preferably of the following monomers
• the monomers a) used include acrylic monomers which comprise acrylic and methacrylic esters having alkyl groups consisting of 4 to 14 carbon atoms, preferably 4 to 9 carbon atoms.
• acrylic monomers which comprise acrylic and methacrylic esters having alkyl groups consisting of 4 to 14 carbon atoms, preferably 4 to 9 carbon atoms.
• Specific examples without wishing to be restricted unnecessarily by this enumeration, are n-butyl acrylate, n-pentyl acrylate, n-hexyl acrylate, n-heptyl acrylate, n-octyl acrylate, n-nonyl acrylate, lauryl acrylate, stearyl acrylate, behenyl acrylate, and their branched isomers, such as 2-ethylhexyl acrylate, for example.
• Further classes of compound which can likewise be added in small amounts under a) are methyl meth
• photoinitiators with at least one vinyl compound are used for the monomers b).
• the photoinitiators may be of the Norrish I or Norrish II type.
• the photoinitiators include as a building block, preferably, one or more of the following radicals:
• acrylated benzophenone such as Ebecryl P 36TM from UCB, for example, or benzoin acrylate.
• monomers c) used include vinyl esters, vinyl ethers, vinyl halides, vinylidene halides, vinyl compounds with aromatic rings and heterocycles in ⁇ -position.
• vinyl esters, vinyl ethers, vinyl halides, vinylidene halides, vinyl compounds with aromatic rings and heterocycles in ⁇ -position include vinyl esters, vinyl ethers, vinyl halides, vinylidene halides, vinyl compounds with aromatic rings and heterocycles in ⁇ -position.
• monomers c) monomers having the following functional groups are employed: hydroxyl, carboxyl, epoxy, acid amide, isocyanato or amino groups.
• acrylic monomers are used for c) that conform to the following general formula where R 1 ⁇ H or CH 3 and the radical —OR 2 represents or includes the functional group and, for example, in one particularly preferred version, possesses an H-donor effect, which facilitates the UV crosslinking.
• component c) are hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, allyl alcohol, maleic anhydride, itaconic anhydride, itaconic acid, acrylamide, and glyceridyl methacrylate, benzyl acrylate, benzyl methacrylate, phenyl acrylate, phenyl methacrylate, tert-butylphenyl acrylate, tert-butylphenyl methacrylate, phenoxyethyl acrylate, phenoxyethyl methacrylate, 2-butoxyethyl methacrylate, 2-butoxyethyl acrylate, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, diethylaminoethyl acrylate, dieth
• aromatic vinyl compounds are used for component c), the aromatic nuclei consisting preferably of C 4 to C 18 and also being able to contain heteroatoms.
• Particularly preferred examples are styrene, 4-vinylpyridine, N-vinylphthalimide, methylstyrene, 3,4-dimethoxystyrene, and 4-vinylbenzoic acid; this enumeration should likewise not be understood as exhaustive.
• the monomers are chosen such that the resultant polymers can be employed as industrially useful PSAs, particularly such that the resulting polymers possess pressure-sensitive adhesion properties in accordance with the “Handbook of Pressure Sensitive Adhesive Technology” by Donatas Satas (van Nostrand, New York 1989).
• the static glass transition temperature of the resultant polymer is advantageously below 25° C.
• the polymerization is carried out preferably using a control reagent of the general formula: in which R and R′ are chosen independently of one another or are the same, and which come from the following list:
• Control reagents of type (I) consist in a more preferred version of the following compounds.
• Halogens in this case are preferably F, Cl, Br or I, more preferably Cl and Br.
• alkyl, alkenyl, and alkynyl radicals in the various substitutents outstanding suitability is possessed by both linear and branched chains.
• alkyl radicals containing 1 to 18 carbon atoms examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, 2-pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, tert-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 examples include 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 C 2 -C 18 hetero-alkyl radical having at least one oxygen atom in the carbon chain is, for example, —CH 2 —CH 2 —O—CH 2 —CH 3 .
• radicals serving as C 3 -C 12 cycloalkyl radicals include cyclopropyl, cyclopentyl, cyclohexyl or trimethylcyclohexyl.
• radicals serving as C 6 -C 18 aryl radicals include phenyl, naphthyl, benzyl, 4-tert-butylbenzyl- or further substituted phenyl, such as, for example, ethyl, toluene, xylene, mesitylene, isopropylbenzene, dichlorobenzene or bromotoluene.
• compounds (Ia) and (IIa) are used as control reagents.
• initiator systems which additionally contain further free-radical initiators for the polymerization, especially thermally decomposing free-radical-forming azo or peroxo initiators.
• Suitable in principle for this purpose are all customary initiators that are known for acrylates.
• the production of C-centered radicals is described in Houben Weyl, Methoden der Organischen Chemie, vol. E 19a, pages 60 to 147. These methods are preferentially employed analogously.
• free-radical sources are peroxides, hydroperoxides, and azo compounds; as a number of nonexclusive examples of typical free-radical initiators, mention may be made here of potassium peroxodisulfate, dibenzoyl peroxide, cumene hydroperoxide, cyclohexanone peroxide, di-tert-butyl peroxide, cyclohexylsulfonyl acetyl peroxide, diisopropyl percarbonate, tert-butyl peroctoate, and benzpinacol.
• the free-radical initiator used is 2,2′-azobisisobutyronitrile (Vazo 64TM from DuPont).
• the average molecular weights M w (weight averages) of the polymers formed in the controlled free-radical polymerization are chosen such that they are situated within a range of 100 000 and 800 000 g/mol; specifically for further use as hotmelt PSAs, PSAs are produced which have average molecular weights (weight averages) M w of 100 000 to 350 000 g/mol.
• the average molecular weight M w is determined in each case via size exclusion chromatography (gel permeation chromatography, GPC) or matrix-assisted laser-desorption/ionization coupled with mass spectrometry (MALDI-MS).
• the polymerization takes place in bulk without addition of solvents.
• the thermally decomposing initiators For initiating the polymerization it is essential, for the thermally decomposing initiators, to introduce heat.
• the thermally decomposing initiators the polymerization can be initiated by heating to 50 to 160° C., depending on initiator type.
• one or more plasticizers are metered in to the polyacrylates, such as, for example, low molecular weight polyacrylates, phthalates, phosphates, citrates, and water-soluble plasticizers (whale oil plasticizers).
• the polyacrylates may further be blended with one or more additives such as aging inhibitors, light stabilizers, ozone protectants, fatty acids, nucleators, expandants, compounding agents and/or accelerants.
• aging inhibitors reference may be made in particular to primary and secondary aging inhibitors, which are available commercially under the tradenames IrganoxTM from Ciba Geigy and HostanoxTM from Clariant.
• the invention also provides for the particularly preferred use of the polyacrylate pressure-sensitive adhesive for an adhesive tape, it being possible for the polyacrylate pressure-sensitive adhesive to have been applied to one or both sides of a carrier.
• Carrier materials used for the PSA, for adhesive tapes for example are the customary materials familiar to the skilled worker, such as films (polyesters, PET, PE, PP, BOPP, PVC), nonwovens, foams, woven fabrics, and woven films, and also release paper (glassine, HDPE, LDPE). This enumeration should likewise not be understood as exhaustive.
• the polyacrylate (the resultant polymer) is applied, preferably inline, to a carrier or to a carrier material, in the form of a layer.
• the PSA utility it is particularly advantageous to crosslink the polyacrylates after they have been coated onto the carrier or onto the carrier material.
• the above-described polymers are for this purpose blended, optionally, with crosslinkers.
• Preferred substances in accordance with the inventive method that crosslink under radiation are, for example, difunctional or polyfunctional acrylates or difunctional or polyfunctional urethane acrylates, difunctional or polyfunctional isocyanates or difunctional or polyfunctional epoxides.
• Noncopolymerized photoinitiators Suitable for this purpose are, preferably, Norrish type I and type II cleaving compounds, a number of possible examples of both classes being benzophenone derivatives, acetophenone derivatives, benzil derivatives, benzoin derivatives, hydroxyalkylphenone derivatives, phenyl cyclohexyl ketone derivatives, anthraquinone derivatives, thioxanthone derivatives, triazine derivatives, or fluorenone derivatives, this enumeration possessing no claim to completeness.
• benzophenone derivatives acetophenone derivatives, benzil derivatives, benzoin derivatives, hydroxyalkylphenone derivatives, phenyl cyclohexyl ketone derivatives, anthraquinone derivatives, thioxanthone derivatives, triazine derivatives, or fluorenone derivatives, this enumeration possessing no claim to completeness.
• UV crosslinking takes place very preferably by means of brief ultraviolet irradiation in a wavelength range from 200 to 450 nm, particularly using high-pressure or medium-pressure mercury lamps with an output of 80 to 240 W/cm.
• monochromatic radiation in the form of lasers.
• it may be appropriate to shade off part of the UV beam path.
• special reflector systems which function as cold light emitters in order thus to prevent instances of overheating.
• Typical irradiation equipment that can be employed includes linear cathode systems, scanner systems and/or segmented cathode systems, where the devices in question are electron beam accelerators.
• the polymerization was implemented using as reactor a planetary roller extruder consisting of three roller barrels in series.
• the roller barrels used have a roller diameter D of 70 mm and were equipped with 7 planetary spindles. Both central spindle and roller barrels are fitted with separate temperature-control circuits.
• the temperature-control medium used was pressurized water.
• the reactor is operated continuously. Prior to the beginning of metering the reactor is flushed with nitrogen for 1 hour. A mixture is produced from monomers and initiator. This initial mixture is rendered inert by nitrogen being passed through it. By means of a pump, the reaction mixture is conveyed through a static mixer, which is fitted with further feed devices, and then through a heat exchanger into the reactor. The reaction mixture is added continuously to the reactor via a hole drilled at the beginning of the first roller barrel. Located at the exit from the reactor is a valve by means of which the hydraulic filling of the reactor is ensured.
• the heat exchanger for feed preheating, central spindle, and roller barrels are controlled with the particular desired temperatures.
• the central spindle a temperature of 80° C. was set; the medium for feed preheating was set at 90° C.
• Roller barrels 1 and 3 were controlled to 100° C., roller barrel 2 to 95° C.
• the speed of the central spindle was 50 revolutions per minute.
• the hydrodynamic residence time was 15 minutes. Following emergence from the reactor, a sample is taken to determine the conversion. Subsequently, volatile constituents still present are removed in a devolatilizing extruder.
• the adhesive is coated at an application rate of 50 g/m 2 via a hotmelt coater having two heatable rolls onto a Saran-primed PET film 23 ⁇ m thick.
• UV irradiation was carried out using a UV unit from Eltosch.
• the unit is equipped with a medium-pressure Hg UV lamp having an intensity of 120 W/cm.
• the swatch specimens produced by method B were each run through the unit at a speed of 20 m/min, the specimens being irradiated in a plurality of passes in order to increase the irradiation dose.
• the UV dose was measured using the Power Puck from Eltosch.
• the dose of one irradiation pass was approximately 140 mJ/cm 2 in the UV-B range and 25 mJ/cm 2 in the UV-C range.
• 2,2′-Bis(phenylethyl)thiocarbonate is synthesized starting from 2-phenylethyl bromide with carbon disulfide and sodium hydroxide in accordance with instructions from Synth. Communications 18(13), pp. 1531-1536, 1988. Yield after distillation: 72%.
• the copolymerizable photoinitiator used was benzoin acrylate.
• the conversion rate was determined by gravimetry and is expressed as a percentage in relation to the amount by weight of monomers employed. To isolate the polymer it is dried in a vacuum cabinet. The weight of the polymer is weighed and divided by the initial mass of monomers employed. The calculated value corresponds to the percentage conversion.
• the average molecular weight M w and the polydispersity PD were determined by gel permeation chromatography.
• the eluent used was THF containing 0.1% by volume trifluoroacetic acid. Measurement took place at 25° C.
• the precolumn used was PSS-SDV, 5 ⁇ , 10 3 ⁇ , ID 8.0 mm ⁇ 50 mm. Separation was carried out using the columns PSS-SDV, 5 ⁇ , 10 3 and also 10 5 and 10 6 each with ID 8.0 mm ⁇ 300 mm.
• the sample concentration was 4 g/l, the flow rate 1.0 ml per minute. Measurement was carried out against PMMA standards.
• a strip of the adhesive tape 13 mm wide, was applied to a smooth steel surface which had been cleaned three times with acetone and once with isopropanol. The area of application measured 20 mm ⁇ 13 mm (length ⁇ width). Subsequently the adhesive tape was pressed onto the steel support four times using a 2 kg weight. At room temperature (RT) a 1 kg weight was affixed to the adhesive tape, and a measurement was made of the time taken for the weight to drop off.
• RT room temperature
• the holding power times (HP) measured are reported in minutes and correspond to the average from three measurements.
• a strip 20 mm wide of an acrylate PSA applied as a layer to polyester was applied to steel plates.
• the PSA strip was pressed onto the substrate twice using a 2 kg weight.
• the adhesive tape was subsequently peeled from the substrate immediately at 300 mm/min and at an angle of 180°.
• the steel plates were washed twice with acetone and once with isopropanol. The measurement results are reported in N/cm and are averaged from three measurements. All measurements were carried out at room temperature.
• a polymer was prepared by method A. 5% of acrylic acid, 95% of n-butyl acrylate and 0.015% of azoisobutyronitrile (AIBN, Vazo 64TM, DuPont) were used.
• the average molecular weight and the polydispersity were determined by means of test B, the conversion by test A, and the gel index by test C.
• the specimen was tested in accordance with tests C, D and E.
• a polymer was prepared by method A. 4.5% of acrylic acid, 95% of n-butyl acrylate, 0.5% of benzoin acrylate and also 0.124% of 2,2′-bis(phenylethyl)thiocarbonate and 0.015% of azoisobutyronitrile (AIBN, Vazo 64TM, DuPont) were used.
• the average molecular weight and the polydispersity were determined by means of test B, the conversion by test A, and the gel index by test C.
• a polymer was prepared by method A. 0.5% of acrylic acid, 49.5% of n-butyl acrylate, 49.5% of 2-ethylhexyl acrylate, 0.5% of benzoin acrylate and also 0.124% of 2,2′-bis(phenylethyl)thiocarbonate and 0.015% of azoisobutyronitrile (AIBN, Vazo 64TM, DuPont) were used.
• the average molecular weight and the polydispersity were determined by means of test B, the conversion by test A, and the gel index by test C.
• the specimen was tested in accordance with tests C, D and E.
• Table 2 shows the results of the crosslinking and technical adhesive evaluation of the swatch specimens.
• TABLE 2 Gel index Gel index Exam- [%] after [%] after BS - steel HP at RT ple polymerization UV crosslinking [N/cm] [min] 1 0 0 2 0 48 5.2 >10 000 3 0 46 4.5 2780 HP: Holding Power RT: Room Temperature BS: Bond Strength
• Example 1 serves as a reference example.
• examples 2 to 3 are attached.
• acrylate PSAs were produced with copolymerized photoinitiator and with a low molar mass. Through the use of a regulator, polymers were obtained which had a narrow-distribution molecular weight distribution.
• Example 1 is very high molecular weight and cannot be coated. Through the use of the regulator in the case of example 2 and 3 the molecular weight is lowered to an extent such that coating, which is necessary for application in the adhesive tape, is possible.
• example 2 with an Mw of 593 000 g/mol, is coatable at 120° C.
• example 3 with a lower Mw of 487 000 g/mol, is coatable at just 110° C.

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