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
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/10—Adhesives in the form of films or foils without carriers
• • 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
  • 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
  • C09J133/06—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
  • C09J133/08—Homopolymers or copolymers of acrylic acid 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
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/005—Diaphragms
• • 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
  • C08F220/16—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms
  • C08F220/18—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms with acrylic or methacrylic acids
  • C08F220/1808—C8-(meth)acrylate, e.g. isooctyl (meth)acrylate or 2-ethylhexyl (meth)acrylate
• • 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
  • C09J2203/00—Applications of adhesives in processes or use of adhesives in the form of films or foils
• • 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
  • C09J2301/00—Additional features of adhesives in the form of films or foils
  • C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
  • C09J2301/302—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier the adhesive being pressure-sensitive, i.e. tacky at temperatures inferior to 30°C
• • 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
  • C09J2301/00—Additional features of adhesives in the form of films or foils
  • C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
  • C09J2301/312—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier parameters being the characterizing feature
• • 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
  • C09J2433/00—Presence of (meth)acrylic polymer
• • 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
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/28—Web or sheet containing structurally defined element or component and having an adhesive outermost layer
  • Y10T428/2852—Adhesive compositions
  • Y10T428/2878—Adhesive compositions including addition polymer from unsaturated monomer
  • Y10T428/2891—Adhesive compositions including addition polymer from unsaturated monomer including addition polymer from alpha-beta unsaturated carboxylic acid [e.g., acrylic acid, methacrylic acid, etc.] Or derivative thereof

Definitions

• Thermal management the provision of electrical functions and other tasks, such display systems usually have transparent protective windows that cover the outside of the display modules.
• Adhesive tapes which are used for bonding components or substrates which serve optical purposes or are used for optical apparatus must frequently be light-reflecting, light-absorbing, highly transparent and / or light-resistant. Furthermore, it may be important to exclude air This has the advantage that the reflection is reduced, which results from the transition from air to eg optical medium made of glass. For example, in the bonding of glasses or plastic windows for displays, panels or the like even the smallest bubbles inclusions can adversely affect the appearance of the image.
• the nature of the surfaces of substrate and adhesive is of crucial importance. A particularly smooth PSA surface is required for the bonding of optical components, because perfect lamination of the equally smooth optical substrates is necessary to obtain a defect-free optical component.
• the object of the invention is to provide a pressure-sensitive adhesive which can be used excellently for the bonding of optical components, meets the high requirements in this area of application and at least largely overcomes the disadvantages of the prior art.
• cohesive PSAs are to be made available which are suitable for the formation of layers with very smooth surfaces.
• the object is achieved by an adhesive tape having at least one layer of a pressure-sensitive adhesive based on a polyacrylate having a weight-average molecular weight M w in the range of 200,000 ⁇ M w ⁇ 1 000 000 g / mol, which is the polymerization product of at least the following components
• R 1 represents a hydrocarbon radical having 4 to 14 carbon atoms, with particular advantage branched and / or unbranched, saturated and / or unsaturated hydrocarbon radicals are used;
• component (a) comprises only one monomer, the glass transition temperature T G aH of the homopolymer of the monomer of
• Component (a) [defined as the glass transition temperature T g according to DIN 53765: 1994-03 (. See section 2.2.1)] is not more than - 20 0 C.
• the glass transition temperature T G , a c of the copolymer of the monomers of the component (a) according to the Fox equation is not more than - 20 0 C, wherein for the calculation in the Fox equation, the glass transition temperature values T 9 according to DIN 53765: 1994-03 (see Section 2.2.1) of the homopolymers of the individual monomers of component (a) are used;
• Glass transition temperature T G bH of the homopolymer from the monomer of component (b) is not less than 0 0 C
• Monomers of the component (b) according to the Fox equation is not less than 0 0 C, wherein for the calculation in the Fox equation the glass transition temperature values T 9 according to DIN 53765: 1994-03 (see Section 2.2.1) Homopolymers of the individual monomers of component (b) are used;
• crosslinked polyacrylate is characterized by a loss factor (tan ⁇ value) between 0.2 and 0.4,
• crosslinked polyacrylate has a shear strength which is characterized by a maximum deflection x max in the micro-shear test of 200 to 600 microns, and wherein the crosslinked polyacrylate characterized by an elastic content in the polyacrylate of at least 60%, determined in the micro-shear test.
• the loss factor tan ⁇ is a measure of the elasticity and fluidity of the substance under investigation.
• the sizes can be determined with the help of a rheometer.
• the material to be examined is exposed to a sinusoidal oscillating shear stress in a plate-and-plate arrangement, for example.
• the deformation as a function of time and the time offset of this deformation y are compared with the introduction of the shear stress T (tau).
• This time offset phase shift between shear stress and deformation vector
• ⁇ delta
• the data concerning the maximum shear path and the elastic part refer to the results of the shear path measurement.
• the elastic part is a quantitative measure for describing the resilience of the investigated sample.
• the measurement principle is shown schematically in FIG. 1 (FIG. 1 a: plan view of the measurement setup, FIG. 1 b: side view of the measurement setup).
• a 50 ⁇ m thick layer is produced and crosslinked.
• the polyacrylate layer adheres to a stabilizing film, such as a PET Foil. From this composite, a sample pattern [length (L 1 ) 50 mm, width (B) 10 mm] is cut out.
• the composite of polyacrylate layer (1) and stabilizing film (2) is glued to the polyacrylate layer side in such a manner previously cleaned with acetone steel plate (3) 5 that the steel plate (3) projects beyond the tape right and left and that the adhesive tape ( 1) the steel plate at the top by a distance (a) of 2 mm surmounted.
• the bonding site is then overrolled six times with a 2 kg steel roll, so that there is a firm bond.
• the composite strip (1, 2) is flush with a stable reinforcing strip (4), such as cardboard, on top of the film side, on which a distance sensor (deflection sensor) (5) rests.
• the sample is suspended vertically by means of the steel plate.
• the measurement conditions are a temperature of 40 0 C and the rest
• the sample to be measured is provided at the lower end by means of a clamp (7) (weight of the clamp 6.3 g) with a weight (6) of 500 g (total load 506.3 g) and for a period of time ( ⁇ ti) of 15 min loaded (see Figure 1 c). Due to the firm bonding of the polyacrylate layer (1) on the steel plate (3) and on the stabilizing film (2) act on the polyacrylate layer
• the shearing distance maximum deflection of the distance sensor
• the invention furthermore relates to the use of such an adhesive tape for bonding optical components, ie a method for bonding optical components by means of an adhesive tape, wherein the adhesive tape comprises at least one layer of a PSA based on a polyacrylate having a weight-average molecular weight M w in the range of 200,000 ⁇ M w ⁇ 1 000 000 g / mol, which is obtainable by radical copolymerization of at least the following components:
• Ri represents a hydrocarbon radical having 4 to 14 carbon atoms, with particular advantage branched and / or unbranched, saturated and / or unsaturated hydrocarbon radicals are used;
• component (a) comprises only one monomer
• Glass transition temperature T G, aH of the homopolymer from the monomer of component (a) is not more than - is 20 0 C.
• component (a) comprises more than one monomer, the glass transition temperature T G aC of the copolymer of the monomers of
• Komonente (a) according to the Fox equation is not more than - 20 0 C, wherein for the calculation in the Fox equation glass transition temperature value T 9 53765 according to DIN: 1994-03 (see Section 2.2.1.) Of the homopolymers the individual monomers of component (a) are used;
• the glass transition temperature T G , b H of the homopolymer of the monomer of component (b) is not less than 0 ° C or wherein, when the component (b) comprises more than one monomer, the glass transition temperature T G , bc of the copolymer of the monomers of the component (b) according to the Fox equation is not less than 0 0 C, wherein for the calculation in the Fox equation the glass transition temperature value T g according to DIN 53765: 1994-03 (see Section 2.2.1) of the homopolymers of the individual monomers of component (b) are used;
• Loss factor (tan ⁇ value) is characterized between 0.2 and 0.4
• the polyacrylate having a shear strength which is characterized by a maximum deflection x max in the micro-shear test from 200 to 600 ⁇ m,
• crosslinked polyacrylate is characterized by an elastic content in the polyacrylate of at least 60%, determined in the micro-shear test.
• the term "for the bonding of optical components" is understood to mean any bond which serves for optical purposes, in particular adhesions which place high demands on the PSA on account of the light management associated with the bonded substrates.
• Exemplary uses which fall in particular under the claimed use are the use of the adhesive tapes according to the invention for the lamination of polarizer films, retarder films, light-enhancement films, lightguide films, antireflection films, antiglare films, shatter-proofing films, on LCD modules, mutually on one of the films mentioned or on transparent substrates with structural function; Furthermore, the bonding of glasses, plastic films, plastic windows and the like in the production of optical data displays (LCDs, liquid crystal displays), OLED displays (organic light-emitting diode displays), other displays, so-called touch panels, screens (monitor windows) and the like.
• LCDs liquid crystal displays
• OLED displays organic light-emitting diode displays
• touch panels screens (monitor windows) and the like.
• the aforementioned uses are particularly relevant in the field of electronic devices, such as for televisions, computer monitors, radars, oscilloscopes, portable computers (notebooks), PDAs (handhelds, organizers), mobile phones, digital cameras, camcorders, navigation devices, clocks, level indicators on storage vessels and the same.
• electronic devices such as for televisions, computer monitors, radars, oscilloscopes, portable computers (notebooks), PDAs (handhelds, organizers), mobile phones, digital cameras, camcorders, navigation devices, clocks, level indicators on storage vessels and the same.
• the bonding of decorative elements falls under the claimed use, in particular if this demanding bonding are connected.
• the elastic portion (micro-shear test) of the polyacrylate of the adhesive tape according to the invention and of the adhesive tape used in accordance with the invention are adjusted to be in the range between 70% and 95%.
• the polymerization of the polyacrylate is carried out in particular by free radical polymerization of the comonomers used according to known polymerization.
• the Fox equation can be used to determine the glass transition temperature of copolymers (see TG Fox, Bull. Am. Phys Soc., 1 (1956) p. 123), which states that the reciprocal glass transition temperature of the copolymer exceeds the proportions by weight of the copolymers calculated comonomers and the glass transition temperatures of the corresponding homopolymers of comonomers can be calculated:
• W 1 and w 2 represent the mass fraction of the respective monomer 1 or 2 (wt .-%) and T G , i and T G 2, the respective glass transition temperature of the homopolymer of the respective monomers 1 and 2 in K (Kelvin).
• n represents the number of runs via the monomers used, w n the mass fraction of the respective monomer n (wt .-%) and T G , n the respective glass transition temperature of the homopolymer of the respective monomers n in K (Kelvin).
• T G the respective glass transition temperature of the homopolymer of the respective monomers n in K (Kelvin).
• the values for the glass transition temperatures of the corresponding homopolymers can also be taken from relevant reference works.
• the hydrocarbon radical of the acrylic monomers for component (a) may in particular be a branched or unbranched alkyl or alkenyl group. Particularly advantageous are hydrocarbon radicals having 4 to 10 carbon atoms.
• acrylic monomers which can be used in the sense of component (a) 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 the like branched isomers, such as Isobutyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate.
• component (b) in a preferred procedure, at least partially one or more acrylic and / or methacrylic monomers of the general formula
• the hydrocarbon radical of a respective acrylic monomer for component (b) may be branched or unbranched, saturated or unsaturated, aliphatic or aromatic, substituted or unsubstituted.
• advantageous monomers in the sense of component (b) can be, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, use Isooctylmethacrylat.
• Further advantageous monomers for component (b) are monofunctional acrylates and / or methacrylates of bridged cycloalkyl alcohols which have at least 6 C atoms.
• the cycloalkyl alcohols may also be substituted, for example by C 1-6 -alkyl groups, halogen atoms or cyano groups.
• Advantageous examples of such monomers are cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate and 3,5-dimethyl adamantyl acrylate.
• non-acrylic monomers can be used which have a high static glass transition temperature (in particular T G ⁇ 0 ° C).
• aromatic vinyl compounds such as, for example, styrene, are suitable, where the aromatic nuclei preferably consist of C 4 - to C 18 -components and may also contain heteroatoms.
• Particularly preferred examples are 4-vinylpyridine, N-vinylphthalimide, methylstyrene, 3,4-dimethoxystyrene, 4-vinylbenzoic acid.
• acrylic monomers having aromatic radicals in the sense of component (b) can also be used, for example benzyl acrylate, benzyl methacrylate, phenyl acrylate, phenyl methacrylate, t-butylphenyl acrylate, t-butylphenyl methacrylate, biphenyl A-acrylate and methacrylate, 2-naphthyl acrylate and methacrylate , the compounds of component (c) are added as comonomers.
• the crosslinking of the polyacrylate can be effected by thermal crosslinking and / or chemical crosslinking and / or by actinic radiation (in particular UV radiation or electron radiation).
• actinic radiation in particular UV radiation or electron radiation.
• the setting of the parameters mentioned in the claims can be carried out in particular by a targeted crosslinking.
• the crosslinking is then carried out to a degree of crosslinking which is characterized by a loss factor (tan ⁇ value) between 0.2 and 0.4, a micro-shear of 200 to 600 microns and an elastic content in the polyacrylate of at least 60%.
• the setting of such a degree of crosslinking is one of the general knowledge of the skilled person, in particular of those skilled in the field of adhesives and self-adhesives, and is readily practicable by him with his expertise.
• component (c) may advantageously exclusively or at least partially, in the second case particularly advantageous in combination with copolymerizable photoinitiators, in particular as hereinafter referred to, one or more acrylic and / or methacrylic monomers of the general formula
• functional groups in the above sense for example, carbonyl groups, acid groups, hydroxy groups, epoxy groups, amine groups, isocyanate groups can be selected.
• component (c) is employed in an amount such that the amount of substance n a [in moles] of the monomers of component (a) corresponds to the molar amount n c [in moles] of the functional groups of component (c). in the ratio 1 ⁇ n a / n c ⁇ 20, preferably 5 ⁇ n a / n c ⁇ 16, more preferably 6 ⁇ n a / n c ⁇ 1 1.
• the glass transition temperature T G, CH of the homopolymer of the acrylic or methacrylic monomer of component (c) is not less than 0 ° C, or, if component (c) comprises a plurality of acrylic and / or methacrylic monomers, the glass transition temperature T G , cc of Copolymer of the acrylic and / or methacrylic monomers of component (c) according to the Fox equation is not less than 0 ° C, wherein for the calculation in the Fox equation the glass transition temperature value T 9 according to DIN 53765: 1994-03 ( see Section 2.2.1) of the homopolymers of the individual monomers of component (c).
• corresponding functionalized (meth) acrylic monomers in the sense of component (c) are acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, allyl alcohol, maleic anhydride, itaconic anhydride, itaconic acid, glyceridyl methacrylate, phenoxyethyl acrylate, phenoxyethyl methacrylate, 2-butoxyethyl methacrylate, 2-butoxyethyl acrylate, cyanoethyl methacrylate, cyanoethyl acrylate, glyceryl methacrylate, 6-hydroxyhexyl methacrylate, vinyl acetic acid, tetrahydrofurfuryl acrylate, ⁇ -acryloyloxypropionic acid, trichloroacrylic acid, fumaric acid, crotonic acid, a
• copolymerisable photoinitiators may advantageously be used exclusively or else in part, in the latter case in particular in combination of the abovementioned compounds in the sense of component (c).
• copolymerizable photoinitiators are Norrish I photoinitiators (photochemically fragmenting, in particular ⁇ -cleaving photoinitiators) and
• Norrish II photoinitiators photochemically excited hydrogen-abstracting photoinitiators
• copolymerizable photoinitiators include benzoin and acrylated benzophenones, for example, the commercially available product Ebecryl P 36 ® from. UCB.
• Crosslinkers and promoters can be added to the polyacrylate for the crosslinking reaction.
• crosslinkers and / or promoters can optionally already be added before or during the polymerization.
• Suitable crosslinkers for electron beam crosslinking and UV crosslinking are, for example, difunctional or polyfunctional acrylates, difunctional or polyfunctional isocyanates (also in blocked form) or difunctional or polyfunctional epoxides.
• thermally activatable crosslinkers such as Lewis acids, metal chelates or multifunctional isocyanates may be added.
• Useful photoinitiators which are very useful are benzoin ethers, such as benzoin ethers.
• 2-methoxy-2-hydroxypropiophenone aromatic sulfonyl chlorides, such as.
• photoactive oximes such as.
• the above-mentioned and / or further advantageously usable, non-copolymerizable Photoinititatioren may particularly advantageously contain the following radicals: benzophenone, acetophenone, benzil, benzoin, hydroxyalkylphenone, Phenylcyclohexylketon- , Anthrachinon-, Trimethylbenzoylphosphinoxid-, Methylthiophenylmorpholinketon-, aminoketone, azobenzoin, thioxanthone, Hexarylbisimidazol-, triazine or fluorenone, wherein each of these radicals additionally with one or more halogen atoms
• the comonomer mixture to be polymerized, the polymer present in the polymerization and / or the ready-polymerized polyacrylate may be added, preferably before the crosslinking reaction, in particular to support the setting of the desired product properties, further components and / or additives, in particular those additives which do not enter the Polymer are incorporated and / or not participate in the crosslinking reaction.
• additives which are advantageous in particular for the use in the optical range for the polyacrylate of the adhesive tape, there may be mentioned, for example, light stabilizers and anti-aging agents.
• tackifier resins and plasticizers can be dispensed with in the case of the pressure-sensitive adhesive used for the adhesive tape of the invention or for the adhesive tape used according to the invention, such that an outstanding variant of the adhesive tape of the invention and the adhesive tape of the invention each have a PSA layer, in particular by a PSA layer are realized (single-layer, carrierless adhesive tape), in which no resins and / or plasticizers are added to the PSA, in particular advantageously neither resins nor plasticizers are added. Such additives often have adverse effects in the optical bonding application.
• the resins used according to the prior art as tackifier resins for acrylate PSAs are usually polar in nature in order to achieve compatibility with the polyacrylate matrix. This usually leads to the use of aromatic tackifier resins, which turn yellowish upon prolonged storage or under the action of light.
• the polyacrylate obtainable as described above and optionally additized becomes
• Adhesive adhesive layer alone consist (so-called transfer tapes) and are provided on the market on one or both sides with a temporary carrier for previous handling, packaging and offering, in particular wound to the role.
• the polyacrylate obtainable as described above is advantageously applied to a temporary support (in particular anti-adhesive and / or anti-adhesive materials (so-called cover materials, release materials, release materials or (release) liners) such as, for example, siliconized papers, films or the like
• a temporary support in particular anti-adhesive and / or anti-adhesive materials (so-called cover materials, release materials, release materials or (release) liners)
• cover materials release materials, release materials or (release) liners
• release materials suitable for polyacrylate PSAs can be used here.
• adhesive tapes with two (adhesive) layers of adhesive of different types, of which at least one of the layers is a PSA layer according to the invention (described in the context of this document).
• the PSA layers can adjoin one another directly (two-layer adhesive tape), and between the two PSA layers optionally one or more further layers can be provided, such as, for example, carrier layers or the like (multilayer structure).
• the crosslinking of the polyacrylate is preferably carried out in the layer on the carrier material.
• the pressure-sensitive adhesive is preferably adjusted so that the pressure-sensitively adhesive properties are suitable for the use of the PSA for the described intended use. According to the invention, this is preferably done by selecting the appropriate degree of crosslinking of the polyacrylate.
• the polyacrylate is crosslinked in this case to a degree of crosslinking, which requires the realization of the specified parameters. In this way, in particular the cohesion and the adhesion of the PSA and their flow behavior can be regulated.
• the crosslinking of the polyacrylate can be effected thermally (ie by the supply of thermal energy), in very preferred cases the crosslinking temperature is at most 90 ° C., very preferably at most 60 ° C., and in particular the residence time to a maximum of 2 minutes , is very preferably limited to a maximum of 1 minute at this temperature.
• crosslinking temperatures of not more than 90 ° C. can be combined with crosslinking times of not more than one minute and, advantageously, crosslinking temperatures of not more than 60 ° C. and crosslinking periods of not more than two minutes).
• the PSA tapes of the invention are preferably passed through a drying channel.
• the drying channel fulfills two functions.
• the solvents are removed. This is usually done by a gradual heating to avoid drying bubbles.
• the heat is used to initiate thermal crosslinking.
• the required heat input depends on the crosslinker system. For example, metal chelate crosslinking can be carried out even at very low temperatures of 90 ° C., very preferably at 60 ° C. and short contact times, in particular in the drying channel (advantageously a maximum of 2 minutes, preferably a maximum of 1 minute).
• epoxy crosslinks require longer crosslinking times and temperatures of 100 ° C. and higher in order to achieve efficient crosslinking in the drying channel. Furthermore, the heat input is controlled by the drying channel length and the Brugeschindtechnik. It has been found that adhesive tapes according to the invention can be produced with outstanding suitability for use for optical bonds, if exclusively or partially aluminum chelate compounds are used as crosslinkers. In contrast to other crosslinkers, these compounds do not tend to yellow and therefore lead to very clear products. Crosslinked with aluminum chelates polyacrylates also tend over time (for example, during prolonged storage) for post-crosslinking or aging, so that the product properties are retained over a very long period of time.
• adhesive tapes according to the invention can also be obtained by crosslinking by means of UV irradiation, wherein this crosslinking can be carried out alternatively or in addition to other crosslinking methods.
• UV crosslinking is irradiated by short-wave ultraviolet radiation in a wavelength range of 200 to 400 nm, depending on the UV photoinitiator used, in particular using high-pressure mercury or - medium pressure lamps at a power of 80 to 400 W / cm .
• the irradiation intensity is adapted to the respective quantum efficiency of the UV photoinitiator and the degree of crosslinking to be set.
• the irradiation conditions (in particular type of irradiation, intensity, dose and duration) are adapted to the particular chemical composition of the polyacrylates to be crosslinked in particular such that the required parameter values of the crosslinked polyacrylate are achieved and the polyacrylate has the required suitability for the desired applications.
• the following information is used as a guide for parameter ranges in which a control is advantageous.
• a UV-C dose of 50 to 200 mJ / cm 2 , preferably of 75 to 150 mJ / cm 2 .
• the dose was measured with a UV dosimeter from Eltosch.
• the dose can be varied by the power of the UV lamp, or by the irradiation time, which in turn is controlled by the web speed.
• preferably low irradiation intensity (less than 200 mJ / cm 2 UV-C) is irradiated.
• the web speed for a UV crosslinking is preferably between 1 and 50 m / min, depending on the irradiation intensity of the UV lamp.
• the radiator output may be appropriate to adapt the radiator output to the web speed and / or the type of pressure-sensitive adhesive tape.
• the hard UV-C radiation in a wavelength range of less than 300 nm is preferred limited.
• the main use of hard UV-C radiation results in a high crosslinking yield on the PSA surface.
• Lower pressure-sensitive adhesive layers are less strongly crosslinked by the short wavelength radiation. Therefore, the UV irradiation for the inventive method in addition to the UV-C radiation very preferably also contains portions of UV-A and UV-B radiation.
• the pressure-sensitive adhesive tape can be covered before the UV irradiation or the irradiation channel is covered with an inert gas, such as e.g. Nitrogen, flooded.
• Suitable UV radiation devices for example, the companies Eltosch, Fusion and IST ago.
• doped glasses can be used to filter out certain radiation areas.
• the adhesive tape according to the invention and the adhesive tape used according to the invention permit a simple and error-free processing without formation of optical defects, largely independent of the substrate and release material surface quality. It has a good flowability, so that it can be perfectly adapted to the surface of the substrates to be bonded. Nevertheless, the cohesion is sufficiently high to ensure a good bond strength.
• the elastic portion A e ⁇ as t of the polyacrylate is at least 60% (Scherwegteil).
• the surface of the adhesive layer of the adhesive tape according to the invention and of the adhesive tape used according to the invention which is exposed on stripping of an applied release material preferably has a mean roughness R a, io s equal to or less than 70% within a time of 10 s after removal of the applied release material. preferably 60%, the average roughness R a, 0 of the surface of the release material which has been applied to the layer of adhesive, assuming that the average roughness R a, 0 of the adhesive layer exposed by the release of the release material at time 0 (immediately after withdrawal of the release material, "initial value") and that of the surface of the release material which has been applied to the adhesive layer are the same.
• Adhesive tapes according to the invention and adhesives used according to the invention are particularly preferred if the surface roughness of the exposed PSA layer over a period of 24 hours after removal of the release film to a mean roughness R a , 24 h of at most 55%, preferably at most 50%, more preferably at most 45%, even more preferably at most 40% of the initial value decreases.
• Preferred adhesives can assume both of the aforementioned states in the time sequence shown.
• Adhesive tapes according to the invention and adhesive tapes used according to the invention are preferably covered on one or both sides with release materials whose mean roughness R a does not exceed 350 nm, preferably 300 nm, more preferably 150 nm exceeds. In this way it can be ensured that the adhesive layer has a sufficient smoothness for optical applications in the application.
• release materials which can have an average roughness R a of up to 1 nm or even less, the smoothness of the adhesive film can be optimized.
• the PSA is preferably adjusted so that it as a layer up to a layer thickness of 250 .mu.m, preferably up to a layer thickness of 300 .mu.m, a transparency corresponding to a transmission (emitted light intensity based on irradiated light intensity, in%) of at least 95% (after previous deduction of the reflection losses at the interface transitions air / adhesive and adhesive / air) or of at least 89% (emitted light intensity in relation to the absolutely irradiated light intensity, without deduction of the portions of air / adhesive and adhesive / air the incident light intensity, white light C according to standard CIE 13.3-1995).
• the pressure-sensitive adhesive has a Haze value (ASTM D 1003) of at most 5% or less.
• the adhesive tape according to the invention is particularly well suited for permanent adhesive bonds, in particular adhesions in which the adhesive bond is to be permanently retained.
• the bonds can also be carried out over a large area and also be loaded with high weights. This is an advantage for many applications, such as the bonding of glass plates, since the bonded objects or substrates often have a high weight.
• the adhesive tapes according to the invention have good resistance at elevated temperatures.
• the adhesive tapes according to the invention are also outstandingly suitable for use in applications in which the bonding surface is not horizontally planar, for example, is oriented vertically planar, so for example for the bonding of glasses and glass in LCD and plasma TVs.
• a sufficiently high cohesion is required, since these devices are operated in a vertical form and can be heated to temperatures of 40 ° C and more over a longer period.
• the crosslinked polyacrylate of the adhesive tapes according to the invention and the adhesive tapes according to the invention has an elasticity which is characterized by a loss factor (tan ⁇ value) between 0.2 and 0.4, furthermore a shear strength which is determined by a maximum deflection x max in the micro-shear test of 200 to 600 microns, and a resilience, which is characterized by an elastic content in the polyacrylate of at least 60%, determined in the micro-shear test. It is possible according to the invention to provide pressure-sensitive adhesives and adhesive tapes produced therefrom which have high cohesion and high flowability and which are surprisingly able to compensate for the negative effect of surface roughness caused by the application of a release material. The products thus allow excellent gluing in the optical range as well as very good laminations.
• a 200 L reactor conventional for free-radical polymerizations was charged with 4900 g of acrylic acid, 51 kg of 2-ethylhexyl acrylate, 14 kg of methyl acrylate and 53.3 kg of acetone / gasoline / isopropanol (48.5: 48.5: 3). After passing through nitrogen gas with stirring for 45 minutes, the reactor was heated to 58 ° C and 40 g of 2,2'-azoisobutyronitrile (AIBN) was added. Subsequently, the outer heating bath was heated to 75 ° C and the reaction was carried out constantly at this external temperature. After 1 h reaction time again 40 g of AIBN was added.
• AIBN 2,2'-azoisobutyronitrile
• a 200 L reactor conventional for radical polymerizations was charged with 4900 g of acrylic acid, 51 kg of 2-ethylhexyl acrylate, 14 kg of methyl acrylate and 53.3 kg of acetone / gasoline / isopropanol (48.5: 48.5: 2). After passing through nitrogen gas with stirring for 45 minutes, the reactor was heated to 58 ° C and 40 g of 2,2'-azoisobutyronitrile (AIBN) was added. Subsequently, the outer heating bath was heated to 75 ° C and the reaction was carried out constantly at this external temperature. After 1 h reaction time again 40 g of AIBN was added.
• AIBN 2,2'-azoisobutyronitrile
• a conventional for radical polymerizations 200 L reactor was 2.4 kg
• Acrylic acid 38.8 kg of 2-ethylhexyl acrylate, 38.8 kg of n-butyl acrylate and 60 kg
• a conventional for radical polymerizations 200 L reactor was 9.6 kg
• a conventional for radical polymerizations 200 L reactor was 9.6 kg
• Acrylic acid 35.2 kg of 2-ethylhexyl acrylate, 35.2 kg of n-butyl acrylate and 60 kg
• a conventional for radical polymerizations 200 L reactor was 5.6 kg
• Ref e re nzbej spj el5 A 200 L reactor conventional for radical polymerizations was charged with 2800 g of acrylic acid, 10.5 kg of cyclohexyl methacrylate, 56.7 kg of butyl acrylate and 53.3 kg of acetone / gasoline / isopropanol (48.5: 48.5: 2). After passing through nitrogen gas with stirring for 45 minutes, the reactor was heated to 58 ° C and 40 g of 2,2'-azoisobutyronitrile (AIBN) was added. Subsequently, the outer heating bath was heated to 75 ° C and the reaction was carried out constantly at this external temperature. After 1 h reaction time again 40 g of AIBN was added.
• AIBN 2,2'-azoisobutyronitrile
• a 200 L reactor conventional for free-radical polymerizations was charged with 1400 g of acrylic acid, 58.8 kg of 2-ethylhexyl acrylate, 9.8 kg of isobornyl acrylate and 53.3 kg of acetone / gasoline / isopropanol (49.5: 49.5: 1) , After passing through nitrogen gas with stirring for 45 minutes, the reactor was heated to 58 ° C and 40 g of 2,2'-azoisobutyronitrile (AIBN) was added. Subsequently, the outer heating bath was heated to 75 ° C and the reaction was carried out constantly at this external temperature. After 1 h reaction time again 40 g of AIBN was added.
• AIBN 2,2'-azoisobutyronitrile
• the adhesive layer thickness after drying was 50 ⁇ m in each case. On the free
• side B of the polyacrylate layer the surface is referred to, which rests on the first siliconized polyester film, as side A of the polyacrylate layer is the
• a sample sample [length 50 mm, width 10 mm] is cut out. From the sample sample one of the siliconized polyester films is peeled off.
• the sample sample is glued with the exposed polyacrylate layer side onto a steel plate previously cleaned with acetone in such a way that the steel plate projects beyond the adhesive tape to the right and left and the adhesive tape projects beyond the steel plate by a distance of 2 mm at the upper edge.
• the bonding site is then overrolled six times with a 2 kg steel roll, so that there is a firm bond.
• the sample pattern is flush with a sturdy cardboard backing strip on top of the film side, on which a displacement sensor (deflection sensor) rests.
• the sample is suspended vertically by means of the steel plate.
• a temperature of 40 ° C and otherwise norm conditions are chosen.
• the sample to be measured is provided at the lower end by means of a clamp (weight of the clamp 6.3 g) with a weight of 500 g (total load 506.3 g) and loaded for a period of time At 1 of 15 min. Due to the firm adhesion of the polyacrylate layer on the steel plate and on the stabilizing film, shear forces act on the polyacrylate layer.
• the maximum deflection x max of the position sensor after the predetermined duration at constant temperature is indicated as the result in ⁇ m.
• the measurements were carried out in a plate-on-plate configuration using a "RDA II" rheometer manufactured by Rheometrics Dynamic Systems and measuring a round sample with a sample diameter of 8 mm and a sample thickness of 1 mm.
• the sample was obtained by laminating together 20 layers of the adhesive films prepared as above, which were for this purpose freed from the respective carrier material, so that a carrier-free 1 mm thick adhesive film was obtained, from which the round sample could be punched out.
• Measurement conditions temperature 25 ° C, otherwise standard conditions, frequency of the oscillating shear stress 0.1 rad / s.
• the siliconized release film was removed from the adhesive film to be examined on page A.
• a 175 ⁇ m thick polymethyl methacrylate (PMMA) film was laminated to the exposed side of the adhesive film.
• PMMA polymethyl methacrylate
• the second siliconized release film from side B of the adhesive film was peeled off and a second 175 micron thick PMMA film (Plexiglas Superclear®) also laminated on this side.
• the weight-average molecular weight M w was determined by gel permeation chromatography (GPC).
• the eluent used was THF containing 0.1% by volume of trifluoroacetic acid. The measurement was carried out at 25 ° C.
• the precolumn used was PSS-SDV, 5 ⁇ , 10 3 ⁇ , ID 8.0 mm ⁇ 50 mm. For separation, the columns PSS-SDV, 5 ⁇ , 10 3 and 10 5 and 10 6 were used , each with ID 8.0 mm x 300 mm.
• the release material was removed from the adhesive film surface to be examined and, if necessary, the sample was stored open for long-term measurements for the specified period of time in such a manner that the exposed side pointed upward (clean room environment under
• the surface profile was determined with a confocal microscope (type Nanofocus ⁇ scan) and from this the average roughness R a for the characterization of the surface roughness was determined.
• the average roughness R a indicates the average distance of a measuring point on the surface to the center line.
• the center line intersects the true profile within the reference line so that the sum of the profile deviations with respect to the center line becomes minimal, and thus corresponds to the arithmetic mean of all deviations from the
• the mean roughness values R a were measured after a time t of 10 s and after a
• the temporal change ⁇ R a of the average roughness is defined as cn)
• the adhesive tape according to the invention has a low weight average
• the reference examples generally have a very high molecular weight (> 1000000 g / mol), so that the cohesion is relatively high. This results in sufficiently high shear strengths in the micro-shear test, but also only in a very high retention of the surface roughness.
• the following table shows the measured values of the tests on the adhesive surface roughnesses as a function of time (Analytical Method E) for the examples according to the invention.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Adhesive Tapes (AREA)
• Adhesives Or Adhesive Processes (AREA)

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• 2009
  • 2009-07-01 DE DE102009031421A patent/DE102009031421A1/de not_active Withdrawn
• 2010
  • 2010-06-18 WO PCT/EP2010/058607 patent/WO2011000716A1/de active Application Filing
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  • 2010-06-18 KR KR1020127002768A patent/KR20120039685A/ko not_active Application Discontinuation
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