KR20080073754A - Double-sided pressure-sensitive adhesive tapes for producing lc-displays having light-reflecting and absorbing properties - Google Patents

Abstract

The invention relates to a pressure-sensitive adhesive tape, in particular for producing or gluing optical liquid crystal displays (LCDs). Said tape has light-reflecting and light-absorbing properties, a lower side and an upper side, and a support film, which has an upper side and a lower side, said adhesive tape being provided on both sides with an adhesive layer. A silver-coloured or metallic layer is provided at least between the adhesive layer on the lower side of the adhesive tape and the support film and a white paint film is provided at least between the adhesive layer on the upper side of the adhesive tape and the support film.

Description

DOUBLE-SIDED PRESSURE-SENSITIVE ADHESIVE TAPES FOR PRODUCING LC-DISPLAYS HAVING LIGHT-REFLECTING AND ABSORBING PROPERTIES}

The present invention relates to a double-sided pressure-sensitive adhesive tape for producing a liquid crystal data display (LCD) having a multilayer carrier structure, having a multilayer pressure-sensitive adhesive structure, and having light-reflective and light-absorbing properties.

In the age of industrialization, pressure-sensitive adhesive tapes are a widespread processing aid. Particularly for use in the computer industry, very stringent requirements are placed on pressure-sensitive adhesive tapes. Pressure-sensitive adhesive tapes must not only have low outgassing behavior but also be suitable for use over a wide temperature range and must meet certain optical properties.

It is used in the field of optical liquid crystal data display (LCD), which is required for computers, TVs, notebooks, PDAs, mobile phones, digital cameras and the like. 1 shows an example of a double-sided adhesive tape having a black layer for absorption and a layer for reflection according to the prior art; The components for reference numbers are as follows:

1 LCD Glass 8 Reflective Film

2 double-sided black-white adhesive tape 9 LCD casing

3 Pressure sensitive adhesive 10 Black absorbent side of adhesive tape

4 light source (LED) 11 reflective surface

5 light beams 12 visible light range

6 Double-sided adhesive tape 13 "blind" areas

7 optical waveguide

To produce an LC display, an LED (light-emitting diode) as a light source is coupled to the LCD module. Black double-sided pressure-sensitive adhesive tape is generally used for this purpose. The purpose of coloring in black is to prevent light penetrating from inside to outside and from outside to inside in the region of the double-sided pressure-sensitive adhesive tape.

There are already numerous ways to achieve this black coloring. On the other hand, it is desirable to increase the light efficiency of the black optical module, so it is preferable to use a double-sided adhesive tape having black (light-absorbing) on one side and light-reflective on the other side.

In the development of LC displays, there is a trend development. On the one hand, LC displays are becoming lighter and flatter, and the demand for larger displays with higher resolutions is increasing.

For this reason, the design of the display is changing, so the light source is closer to the LCD panel, resulting in more light penetrating from the outside to the surrounding area of the LCD panel (“blind area”). The risk of doing so is increasing (see FIG. 1). Therefore, with this development, the requirements placed on the shade properties (blackout properties) of double-sided adhesive tapes are also increasing, and thus a new method for the production of adhesive tapes is needed.

For this purpose, double-sided pressure-sensitive adhesive tapes with a metal layer and a black carrier on one side are known. With this pressure-sensitive adhesive tape, a marked improvement in light reflection on one side and absorption on the opposite side was obtained.

DE 102 43 215 describes a double-sided adhesive tape for LC displays with light-absorbing properties on one side and light-reflecting properties on the other. This patent describes black / silver double sided PSA tapes. The transparent or colored carrier film has one side metalized and the other side colored black. In this way, the achieved reflective properties are already good, but the absorption properties are still insufficient, which is coated over the defects resulting from the film, for example as a result of the antiblocking agent, so that light can pass through these points (pinholes). Because it can.

However, for the adhesive bonding of the LC, the need for light-reflective and absorptive properties persists, where for the purpose of light absorption the adhesive tape should not have a black layer.

It is therefore an object of the present invention to provide a double-sided pressure-sensitive adhesive tape which prevents the presence of pinholes, can absorb all the light, has no black side for light absorption, and is characterized by improved light reflection.

This object is achieved by the pressure-sensitive adhesive tape of the present invention described in the independent claim. In the context of the present invention, it has surprisingly been found that these properties can be achieved using a film which is metallized on at least one side and provided with at least a white coating layer. The dependent claims relate to advantageous embodiments of the subject matter of the present invention and to the use of the pressure sensitive adhesive tapes of the present invention.

Thus, the independent claims have an upper surface and a lower surface, are light-reflective on the upper and lower surfaces, and are light-absorbing by the carrier structure, one side being white and the other silver. A pressure-sensitive adhesive tape for the production or adhesive bonding of colored optical liquid crystal data displays (LCDs).

The present invention more particularly relates to optical liquid crystal data displays (LCDs) having light-reflective and light-absorbing properties, having a carrier film having an upper surface and a lower surface and additionally having an upper surface and a lower surface in turn. A pressure-sensitive adhesive tape for producing or adhesively bonding, the pressure-sensitive adhesive tape has a pressure-sensitive adhesive layer on both sides and at least a silver-colored, in particular metal layer, between the pressure-sensitive adhesive layer on the bottom surface of the pressure-sensitive adhesive tape and the carrier film. A pressure-sensitive adhesive tape comprising a white coating layer between at least the pressure-sensitive adhesive layer on the upper surface of the pressure-sensitive adhesive tape and the carrier film.

While certain advantageous embodiments of the adhesive tapes of the invention are described below, the selection of examples does not require unnecessary limitations.

The pressure-sensitive layers (b) and (b ') of the two sides of the pressure-sensitive adhesive tape of the present invention may be the same or different in each case more specifically with respect to their arrangement (layer thickness, etc.) and their chemical composition. . Especially preferably, the PSAs on both sides of the pressure-sensitive adhesive tape are transparent. However, in aspects of the present invention, it may be advantageous to color the PSA white on the white side of the pressure sensitive adhesive tape.

In a first advantageous embodiment, the pressure sensitive adhesive film of the invention comprises a carrier film layer (a), a white chromic coating layer (c), two silver-coloured especially metal layers (d) and two transparent pressure sensitive adhesive layers ((b) And (b ')). This embodiment is shown in FIG. 2.

In another preferred embodiment of the invention, as shown in FIG. 3, the double-sided pressure-sensitive adhesive tape comprises a carrier film (a), a white chromogenic coating layer (c), a silver-coloured, in particular metal layer (d), and two pressure-sensitive adhesive layers. (b) and (b ').

The invention is further elucidated below. The specified limit value will be understood as a comprehensive value, that is to say within the stated limit.

The carrier film (a) is preferably 5 to 20 μm, more preferably 8 to 50 μm, most preferably 12 to 36 μm thick, and preferably transparent, white or translucent. However, the film can also be colored differently to reduce the light transmittance of the adhesive tape. The coating layer (c) reflects light and simultaneously absorbs light.

The thickness of the coating layer (c) is preferably 1 μm to 15 μm. In terms of layer (c), there may also be two or more layers superimposed on one another. The layer thickness of the silver-colored, in particular metal layer (s) (d) is preferably 0.01 μm to 5 μm. Here, in one particularly preferred embodiment, aluminum or silver is vapor-coated on the carrier film (a).

The PSA layers (b) and (b ') preferably have a thickness in each case of 5 μm to 250 μm. In the double-sided pressure-sensitive adhesive tape, the thicknesses of the individual layers (a), (c), (b) and (b ') can be applied, for example, to apply PSA layers (b) and (b') of different thicknesses. It may be different, or two or more layers, or all layers, may be selected identically.

Carrier film (a)

As the film carrier, all original film-like carriers, more specifically those that are transparent, translucent or colored can be used. Thus, for example, polyethylene, polypropylene, polyimide, polyester, polyamide, polymethacrylate, fluorinated polymer film, and the like can be used. In one particularly preferred embodiment, a polyester film is used, more preferably a PET (polyethylene terephthalate) film. Such films may be destressed or have one or more optional orientations. The optional direction is obtained by drawing in one or two directions. In general, for the production process for films, PET films, for example, blocking agents such as silicon dioxide, silicon chalk or other chalk, or zeolites are used.

The blocking blocker prevents the flat polymer film from sticking together under pressure and temperature to form the block. Typically blocking blocking agents are introduced into the thermoplastic mixture. In this case, the particles function as spacers.

Advantageously, films of this class can be used for the double-sided adhesive tape of the present invention. However, for the pressure-sensitive adhesive tape of the present invention, a film containing no blocking blocker or containing only a very small amount thereof may also be used. An example of such a film is, for example, Hostaphan ™ 5000 series (PET 5211, PET 5333, PET 5210) from Mitsubishi Polyester Film.

Moreover, very thin films, for example 6 or 12 μm thick films are preferred, in which case the films are very flexible and can adapt well to the surface roughness of the substrate to be bonded, which is a very good technique for double sided adhesive tapes. This is because the adhesive property can be tolerated.

It is very advantageous to pretreat the film to improve the fixation of the coating layer. The film may be etched (eg trichloroacetic acid or trifluoroacetic acid), pretreated by corona or plasma, or may be provided with a primer (eg Saran).

A further and advantageous possibility, in particular when the film material is transparent or translucent, is the addition of color pigments or chromogenic particles to the film material. Thus, for example, titanium dioxide and barium sulphate are suitable for white coloring. However, the pigment or particles should preferably always have a diameter smaller than the final layer thickness of the carrier film. Optimal coloring can be obtained using a particle proportion of 10% to 40% by weight based on the film material.

Coating layer (c)

The coating layer (c) fulfills various functions. In one aspect of the invention, the function of the color layer is the additional absorption of external light. In this case, therefore, the transmittance at a wavelength of 300 to 800 nm for the double-sided pressure-sensitive adhesive tape should be made less than 0.5%, more preferably less than 0.1%, most preferably less than 0.01%.

The coating layer (c) further fulfills the function of light reflection. The light reflection according to test method C shall exceed 65%.

In one very preferred aspect, this is achieved using a white coating layer.

The coating material may be coated as a 100% system from solution or dispersion. The coating material comprises a curable binder matrix (preferably a thermosetting system, or alternatively an irradiation-curing system) and a white color pigment, which is then applied using a printing unit (eg by flexographic printing). do. In order to achieve sufficient opacity, the application is also performed in two or more steps, allowing two or more layers of printing ink to be applied. Moreover, the ink can also be applied using an engraved-roll applicator unit. In this way, it is possible to apply with a relatively thick ink layer thickness in one step.

The coating material may be based on, for example, polyester, polyurethane, polyacrylate or polymethacrylate. In addition, coating additives known to those skilled in the art may be added. The coating material can be irradiated (e.g., electron beam curing with a bifunctional or polyfunctional vinyl compound; for example with UV photocationic generators, bifunctional or multifunctional epoxides, or depending on the base matrix of the coating material) UV free-radical initiators of type Norrrish I or Norish II, in turn bifunctional or multifunctional vinyl compounds such as UV curing with acrylates or methacrylates) or thermally activatable compounds, for example It further contains a crosslinking component for curing which can be activated by difunctional or polyfunctional isocyanates, difunctional or polyfunctional epoxides, difunctional or polyfunctional hydroxides.

In one highly preferred aspect of the invention, the chromic particles mixed in the coating layer are titanium dioxide or barium sulphate. At very high levels of addition (preferably above 20% by weight), this addition forms the function of complete light absorption and affects light reflection. For optimum coloring of the coating layer (c), the particle size distribution of the white color pigment is very important. Therefore, the particles should be at least smaller than the overall thickness of the coating layer (c). One preferred embodiment uses particles having an average diameter of 50 nm to 5 μm, more preferably 100 nm to 3 μm, most preferably 200 nm to 1 μm. This class of grade is obtained, for example, by a controlled screen after performing controlled grinding in a ball mill. The quality of the coloring further requires a uniform distribution of the colored particles in the coating layer. For this purpose, a powerful mixing process is indispensable and, in one optimal embodiment, constitutes a mixing process with Ultraturrax. In this step, the color particles can then be immediately milled again and homogenized in the white coating material.

Silver-colored or metallic layer (d)

For the production of highly reflective and superabsorbent cotton, the silver-colored coating material may be applied to the film layer (a), or the film layer (a) may be steamed on one or both sides of the metal, for example aluminum or silver. Can be coated. For embodiments comprising silver-colored coating materials, the binder matrix is combined with a silver color pigment. Examples of suitable binder matrices include polyurethanes or polyesters having high reflection index and high transmittance. Alternatively, the color pigments can be bonded to a polyacrylate or polymethacrylate matrix and then cured in the form of a coating material.

In a very preferred aspect, the film layer (a) is vapor coated on both sides with aluminum or silver. In order to achieve particularly good semiacid properties, the sputtering process for vapor coating must be controlled in such a way that aluminum or silver is applied very uniformly in order to obtain optimum reflectivity (suppression of the scattering effect). Moreover, in one very preferred embodiment, the PET film is pretreated with a plasma or corona before being vapor coated with aluminum or silver. By using the reflective layer d, on the one hand the light is reflected in a targeted manner, on the other hand the transmission of the light passing through the carrier film is reduced or prevented and also the surface roughness on part of the carrier film is compensated.

PSA (b) and (b ')

In one preferred embodiment, the PSAs (b) and (b ') are identical on both sides of the pressure sensitive adhesive tape. However, in one particular embodiment, it may be advantageous that the PSAs (b) and (b ') also differ from one another in layer thickness and / or chemical composition. In this way, for example, different pressure-sensitive adhesive properties can be set. The PSA system used for the double-sided pressure sensitive adhesive tape of the present invention is preferably an acrylate adhesive, a natural rubber adhesive, a synthetic rubber adhesive, a silicone adhesive or an EVA adhesive. PSAs have high transparency or are colored white.

Moreover, also other PSAs originally known to those skilled in the art can be used, as also cited, for example, in "Handbook of Pressure Sensitive Adhesive Technology" by Donatas Satas (van Nostrand, New York 1989).

For natural rubber adhesives, natural rubber is preferably milled and added to a molecular weight (weight average) of at least about 100,000 Daltons, more preferably at least 500,000 Daltons.

In the case of rubber / synthetic rubber as starting material for the adhesive, it can be widely modified. Natural rubber or synthetic rubber, or any desired blend of natural rubber and / or synthetic rubber, may be used, and natural rubber or natural rubbers may be used in all available grades, for example, depending on the desired purity and viscosity levels. It may be selected from crepe, RSS, ADS, TSR or CV type and the synthetic or synthetic rubbers are randomly copolymerized styrene-butadiene rubber (SBR), butadiene rubber (BR), synthetic polyisoprene (IR), Butyl rubber (IIR), halogenated butyl rubber (XIIR), acrylate rubber (ACM), ethylene-vinyl acetate copolymer (EVA), and polyurethanes and / or blends thereof.

More preferably, thermoplastic elastomers in a weight ratio of 10% by weight to 50% by weight based on the total elastomer fraction may be added to the rubber to improve the processability of the rubber. Representatively, styrene-isoprene-styrene (SIS) and styrene-butadiene-styrene (SBS) types that are specifically compatible in this respect may be mentioned.

In one preferred embodiment of the invention, preferably (meth) acrylate PSA can be used.

The (meth) acrylate PSAs used in the present invention obtainable by free-radical addition polymerization preferably consist of at least 50% by weight of at least one acrylic monomer selected from the group of compounds of the formula:

Wherein the radical R ₁ is H or CH ₃ and the radical R ₂ is selected from groups containing H or CH ₃ or containing branched and unbranched saturated alkyl groups having 1 to 30 carbon atoms.

The monomer is preferably selected such that the polymer obtained can be used at room temperature or higher as PSA, in particular the polymer obtained by Donatas Satas, "Handbook of Pressure Sensitive Adhesive Technology" (van Nostrand, New York 1989). It is selected to be able to have a pressure-sensitive adhesive property according to.

In another embodiment of the invention, the (co) monomer composition is selected such that the PSA can be used as a heat-active PSA.

Such polymers comprise monomer mixtures consisting of acrylic esters and / or methacrylic esters and / or free acids thereof having the formula CH ₂ = CH (R ₁ ) (COOR ₂ ) where R ₁ is H or CH ₃ and R ₂ is Polymerized with 1 to 20 carbon atoms or H).

The molar mass M _w (weight average) of the polyacrylates used is preferably M _w ≧ 200,000 g / mol.

As a very preferred method, acrylic or methacryl monomers consisting of acrylic and methacrylic esters having alkyl groups comprising 4 to 14 carbon atoms, preferably 4 to 9 carbon atoms are used. Specific examples include 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 branched isomers thereof such as isobutyl acrylate, 2-ethylhexyl acrylic Latex, 2-ethylhexyl methacrylate, isooctyl acrylate, and isooctyl methacrylate, and are not limited to this enumeration.

Another class of compounds that can be used are monofunctional acrylates and / or methacrylates of bridged cycloalkyl alcohols consisting of six or more carbon atoms. Cycloalkyl alcohols may also be substituted, for example, with C-1-6 alkyl groups, halogen atoms or cyano groups. Specific examples are cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate, and 3,5-dimethyladamantyl acrylate.

In an advantageous process, polar groups such as carboxyl radicals, sulfonic and phosphonic acids, hydroxyl radicals, lactams and lactones, N-substituted amides, N-substituted amines, carbamates, epoxy, thiols, alkoxy or cyanos Monomers with radicals, ethers and the like are used.

Medium basic monomers include, for example, N, N-dialkyl-substituted amides such as N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N-tert-butylacrylamide, N-vinylpyrrolidone, N-vinyllactam, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, diethylaminoethyl acrylate, N-methylol methacrylamide, N- (Butoxymethyl) methacrylamide, N-methylolacrylamide, N- (ethoxymethyl) acrylamide, and N-isopropylacrylamide, all of which are not described.

Another preferred example is 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, vinylacetic acid, tetrahydrofurfuryl acrylate, β-acryloyloxypropionic acid, trichloroacrylic acid, fumaric acid, crotonic acid, aconic acid, and dimethylacrylic acid, all of which are listed. It is not described.

In another very preferred procedure vinyl esters, vinyl ethers, vinyl halides, vinylidene halides, and vinyl compounds with aromatic rings, and monomers of heterocycles in the α-position are used. Also mentioned herein are some examples, including but not limited to vinyl acetate, vinylformamide, vinylpyridine, ethyl vinyl ether, vinyl chloride, vinylidene chloride, and acrylonitrile.

Moreover, in another procedure, photoinitiators having copolymerizable double bonds can be used. Suitable photoinitiators include Norrish I and II photoinitiators. Examples include benzoin acrylate and acrylated benzophenone (Ebecryl P 36® from UCB). In principle, any photoinitiator that is known to those skilled in the art and capable of crosslinking the polymer by a free-radical mechanism under UV irradiation can be copolymerized. An overview of possible photoinitiators that can be used and can be functionalized by double bonds is provided in Fouassier: "Photoinitiation, Photopolymerization and Photocuring: Fundamentals and Applications", Hanser-Verlag, Munich 1995. Carroy et al., In "Chemistry and Technology of UV and EB Formulations for Caotings, Inks and Paints", Oldring (Ed.), 1994, SITA, London, are used as supplementary materials.

In another preferred procedure, the comonomers described are combined with monomers having a high static glass transition temperature. Suitable components include aromatic vinyl compounds, for example styrene, wherein the aromatic nucleus is preferably composed of C ₄ to C ₁₈ units and may also comprise heteroatoms. Particularly preferred examples include 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-biphenylyl acrylate, 4-biphenylyl methacrylate, 2-naphthyl acrylate, 2-naphthyl methacrylate, and these monomers There is a mixture of and all of these enumerations are not described.

As a result of the increase in the aromatic ratio, the refractive index of the PSA and the scattering rate between the LCD glass and the PSA increase, thereby minimizing external light.

For further development, a resin can be blended into the PSA. As the adhesive resin for the addition, all the adhesive resins already known and described in the literature can be used. Representative examples that may be mentioned include pinene resins, indene resins, and rosines, their disproportionate, hydrogenated, polymerized, esterified derivatives and salts, aliphatic and aromatic hydrocarbon resins, terpene resins and terpene-phenolic resins, and C5, C9, and other hydrocarbon resins. Any desired combination of these and other resins can be used to control the properties of the adhesive obtained according to requirements. In principle, any resin that is compatible (soluble) with the polyacrylates considered may be used: in particular all aliphatic, aromatic and alkylaromatic hydrocarbon resins, hydrocarbon resins based on a single monomer, halogenated hydrocarbon resins, functionalities Hydrocarbon resins, and natural resins can be considered. Reference can be made to the description in the technical field in "Handbook of Pressure Sensitive Adhesive Technology" by Donatas Satas (van Nostrand, 1989).

This transparency is also improved using transparent resins which are preferably very compatible with the polymer. Hydrogenated or partially hydrogenated resins often exhibit this property.

In addition, plasticizers, additional fillers (e.g. fibers, carbon black, zinc oxide, chalk, solid or hollow glass beads, microbeads made of other materials, silica, silicates), nucleating agents, electrically conductive materials For example, conjugated polymers, doped and conjugated polymers, metal pigments, metal particles, metal salts, graphite and the like, extenders, compounding agents and / or aging inhibitors are for example primary and secondary It may be added or not added in the form of primary antioxidants or in the form of light stabilizers, but in this case it should not affect the reflection on the gray side.

In another preferred embodiment of the invention, the PSAs (b) and / or (b ') comprise light-reflecting particles, for example white color pigments (titanium dioxide or barium sulphate) as filler.

In addition, crosslinking agents and promoters for crosslinking may be blended with PSAs (b) and / or (b '). Examples of suitable crosslinkers for electron beam crosslinking and UV crosslinking include bifunctional or polyfunctional acrylates, difunctional or polyfunctional isocyanates (including blocked forms), and difunctional or multifunctional epoxides. In addition, thermally active crosslinkers such as Lewis acids, metal chelates or polyfunctional isocyanates can be added.

To optionally crosslink with UV light, a UV-absorbing photoinitiator can be added. Very effective useful photoinitiators include benzoin ethers such as benzoin methyl ether and benzoin isopropyl ether, substituted acetophenones, for example 2,2-diethoxyacetophenone (available as Irgacure 651® from Ciba Geigy®). Available), 2,2-dimethoxy-2-phenyl-1-phenylethanone, dimethoxyhydroxyacetophenone, substituted α-ketols such as 2-methoxy-2-hydroxypropiophenone, aromatic Sulfonyl chlorides such as 2-naphthylsulfonyl chloride, and photoactive oximes such as 1-phenyl-1,2-propanedione, 2- (O-ethoxycarbonyl) oxime.

The photoinitiators mentioned above and other photoinitiators that may be used, and other photoinitiators of the Norrish I or Norish II type, may contain the following radicals: benzophenone, acetophenone, benzyl, benzoin, hydroxyalkylphenone, phenyl cyclo Hexyl ketone, anthraquinone, trimethylbenzoylphosphine oxide, methylthiophenylmorpholine ketone, aminoketone, azobenzoin, thioxanthone, hexaarylbisimidazole, triazine, or fluorenone; Each of these radicals may be additionally substituted with one or more halogen atoms and / or one or more alkoxy groups and / or one or more amino or hydroxy groups. A representative overview is provided in Fouassier "Photoinitiation, Photopolymerization and Photocuring: Fundamentals and Applications", Hanser-Verlag, Munich 1995. Carroy et al., In "Chemistry and Technology of UV and EB Formulations for Coatings, Inks and Paints", Oldring (Ed.), 1994, SITA, London, can be used as supplementary materials.

How to prepare acrylate PSA

For the polymerization, the monomers are chosen such that the polymer obtained can be used as PSA at room temperature or higher, in particular the polymer obtained by Donatas Satas, "Handbook of Pressure Sensitive Adhesive Technology" (van Nostrand, New York 1989). ], Which can have pressure sensitive adhesive properties.

In order to achieve the desired polymer glass transition temperature T _g of 25 ° C. or lower for PSA, monomers are selected in this manner according to the techniques mentioned above and the Fox equation (TGFox, Bull. Am. Phys. Soc. It is highly desirable to select the quantitative composition of the monomer mixture in this way, advantageously in order to give the desired T _g for the polymer according to an equation (eE1) similar to 1956) 123):

In the above equation, n is the series number of monomers used, w _n is the mass ratio (% weight) of the individual monomers n _, and T _{g, n} is the individual glass transition temperature, K, of the homopolymer of the individual monomers n.

It is advantageous for the conventional free-radical polymerization to be carried out for the preparation of poly (meth) acrylate PSAs. For polymerizations that are treated with free radicals, it is also preferred to use initiator systems which additionally contain free-radical initiators for the polymerization, in particular thermally decomposing free-radical-forming azo or perazo initiators. However, all conventional initiators known to those skilled in the art for acrylates in nature are suitable. The production of C-centric radicals is described by Houben Weyl, Methoden der Organischen Chemie, Vol. E 19a, pp. 60-147. This method is inferred and optionally used.

Examples of free-radical sources include peroxides, hydroperoxides, and azo compounds, and some non-limiting examples of conventional free-radical initiators that may be mentioned herein include potassium peroxodisulfate, dibenzoyl peroxide, Cumene hydroperoxide, cyclohexanone peroxide, di-t-butyl peroxide, azodiisobutyronitrile, cyclohexylsulfonyl acetyl peroxide, diisopropyl percarbonate, t-butyl peroctoate, and Benz Pinacol. In a very preferred embodiment, the free-radical initiator used is 1,1'-azobis (cyclohexane-carbonitrile) (Vazo 88 ™ from DuPont) or azoisobutyronitrile (AIBN).

The weight average molecular weight M _w of the PSAs formed in the free-radical polymerization is very preferably chosen such that they are located within 200,000 to 4,000,000 g / mol; In particular, PSAs having an average molecular weight M _w of 400,000 to 1,400,000 g / mol are prepared for use as conductive hot melt PSAs with resetting capability. Average molecular weights are measured by size exclusion chromatography (GPC) or matrix-assisted laser desorption / ionization mass spectrometry (MALDI-MS).

The polymerization can be carried out in the absence of solvent, in the presence of one or more organic solvents, in the presence of water, or in the presence of a mixture of organic solvents and water. Its purpose is to minimize the amount of solvent used. Suitable organic solvents include straight chain alkanes (e.g. hexane, heptane, octane, isooctane), aromatic hydrocarbons (e.g. benzene, toluene, xylene), esters (e.g. ethyl, propyl, butyl or hexyl acetate), Halogenated hydrocarbons (eg chlorobenzene), alkanols (eg methanol, ethanol, ethylene glycol, ethylene glycol monomethyl ether), and ethers (eg diethyl ether, dibutyl ether) or There is a mixture. Water-miscible or hydrophilic cosolvents may be added to the aqueous polymerization reaction to ensure that the reaction mixture is in the form of a homogeneous phase during monomer conversion. Cosolvents which can be advantageously used in the present invention are aliphatic alcohols, glycols, ethers, glycol ethers, pyrrolidines, N-alkylpyrrolidinones, N-alkylpyrrolidones, polyethylene glycols, polypropylene glycols, amides, carboxyl Acids, and salts, esters, organic sulfides, sulfoxides, sulfones, alcohol derivatives, hydroxy ether derivatives, amino alcohols, ketones, and the like, and derivatives and mixtures thereof.

Depending on the conversion and temperature the polymerization time is from 2 to 72 hours. The higher the reaction temperature that can be selected, ie the higher the thermal stability of the reaction mixture, the shorter the selected reaction time can be.

With regard to the initiation of the polymerization, the introduction of heat is essential for the thermal decomposition initiator. For these initiators, the polymerization reaction can be initiated by heating to 50 to 160 ° C. depending on the initiator type.

For the preparation it may also be advantageous to polymerize the (meth) acrylate PSA without solvent. Particularly suitable techniques for use in this case are prepolymerization techniques. The polymerization is initiated by UV light but only carried out with a low conversion of about 10-30%. The resulting polymer syrup can then be bonded, for example, to a film (in the simplest case ice cube) and polymerized with high conversion in water. Such pellets can then be used as an acrylate hot-melt adhesive, which is particularly preferred for use of film materials compatible with polyacrylates in the melting process. For this preparation method, a thermally conductive material may also be added before or after the polymerization.

Another advantageous preparation method for poly (meth) acrylate PSAs is anionic polymerization. The reaction medium used in this case preferably comprises inert solvents such as aliphatic and cycloaliphatic hydrocarbons, or other aromatic hydrocarbons.

The living polymer is in this case the structure P _L (A) -Me (where Me is a metal from group I, for example lithium, sodium or potassium, and P _L (A) is from an acrylate monomer It is a growing polymer). The molar mass of the polymer at the time of manufacture is adjusted as the ratio of initiator concentration to monomer concentration. Examples of suitable polymerization initiators are n-propyllithium, n-butyllithium, secondary-butyllithium, 2-naphthylithium, cyclohexyllithium, and octylithium, and this enumeration is not fully claimed. Moreover, initiators based on samarium complexes are known for the polymerization of acrylates (Macromolecules, 1995, 28, 7886) and can be used herein.

Moreover, bifunctional initiators such as 1,1,4,4-tetraphenyl-1,4-dirithiobutane or 1,1,4,4-tetraphenyl-1,4-dirithioisobutane can be used Can be. Coinitiators can be used as well. Suitable co-initiators include lithium halides, alkali metal alkoxides, and alkylaluminum compounds. In one highly preferred embodiment, the ligands and co-initiators are selected such that the acrylate monomers such as n-butyl acrylate and 2-ethylhexyl acrylate can be polymerized directly, which is subject to transesterification with the corresponding alcohols. Is not produced in the polymer.

Suitable methods for preparing poly (meth) acrylate PSAs with narrow molecular weight distributions also include controlled free-radical polymerization methods. In this case, it is preferable to use a regulator of the formula for the polymerization:

Wherein R and R ¹ are independently selected from or identical to each other,

Branched and unbranched C ₁ to C ₁₈ alkyl radicals; C ₃ to C ₁₈ alkenyl radicals; C ₃ to C ₁₈ alkynyl radicals;

C ₁ to C ₁₈ alkoxy radicals;

C ₃ to C ₁₈ alkynyl radicals substituted with one or more OH groups or halogen atoms or silyl ethers; C ₃ to C ₁₈ alkenyl radicals; C ₁ to C ₁₈ alkyl radicals;

C ₂ -C ₁₈ heteroalkyl radicals having at least one oxygen atom and / or one NR ^* group in the carbon chain, where R ^* is any radical, in particular an organic radical;

C ₃ to C ₁₈ alkynyl radicals, C ₃ to C ₁₈ alkenyl radicals substituted with one or more ester groups, amine groups, carbonate groups, cyano groups, isocyano groups, and / or epoxide groups and / or sulfur , C ₁ to C ₁₈ alkyl radicals;

C ₃ to C ₁₂ cycloalkyl radicals;

C ₆ to C ₁₈ aryl or benzyl radicals;

-Hydrogen.

Modulators of type (I) preferably comprise the following further-restricted compounds:

Halogen is preferably F, Cl, Br or I, more preferably Cl and Br. Alkyl, alkenyl and alkynyl radicals that are well suited for the various substituents include both linear and branched chains.

Examples of alkyl radicals containing 1 to 18 carbon atoms include 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.

Examples of alkenyl radicals having 3 to 18 carbon atoms include propenyl, 2-butenyl, 3-butenyl, isobutenyl, n-2,4-pentadienyl, 3-methyl-2-butenyl, n -2-octenyl, n-2-dodecenyl, isododecenyl and oleyl.

Examples of 3 to 18 carbon atoms are propynyl, 2-butynyl, 3-butynyl, n-2-octynyl, and n-2-octadecylyl.

Examples of hydroxy-substituted alkyl radicals are hydroxypropyl, hydroxybutyl, and hydroxyhexyl.

Examples of halogen-substituted alkyl radicals are dichlorobutyl, monobromobutyl, and trichlorohexyl.

An example of a suitable C ₂ -C ₁₈ heteroalkyl radical having one or more oxygen atoms in the carbon chain is —CH ₂ —CH ₂ —O—CH ₂ —CH ₃ .

Examples of C ₃ -C ₁₂ cycloalkyl radicals are cyclopropyl, cyclopentyl, cyclohexyl and trimethylcyclohexyl.

Examples of C ₆ -C ₁₈ aryl radicals include phenyl, naphthyl, benzyl, 4-tert-butylbenzyl, and other substituted phenyls such as ethylphenyl, toluene, xylene, mesitylene, isopropylbenzene, dichlorobenzene Or bromotoluene.

The above enumeration is merely provided as an example of a representative group of compounds and is not fully claimed.

Other compounds that may also be used as modulators include compounds of the following types:

Wherein R ² may be selected from the groups cited above for these radicals, independently of R and R ¹ .

In the case of a conventional 'RAFT' process, the polymerization is generally carried out only below low conversion (WO 98/01478 A1) to form a very narrow molecular weight distribution. However, as a result of the low conversion, such polymers cannot be used as PSAs, especially as hot melt PSAs, since high fractions of residual monomers adversely affect particular adhesion properties; This is because residual monomers contaminate solvent recycles during concentration; This is because the corresponding self-adhesive tapes exhibit very high degassing behavior. In order to avoid this drawback of low conversion, one particularly preferred polymerization process is initiated two or more times.

As another controlled free-radical polymerization method, nitroxide-controlled polymerization can be carried out. For free-radical stabilization, nitroxides of type (Va) or (Vb) are used in the preferred procedure:

Wherein R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ independently of one another mean the following compounds or atoms:

i) halides such as chlorine, bromine or iodine,

ii) linear, branched, cyclic or heterocyclic hydrocarbons having from 1 to 20 carbon atoms which may be saturated, unsaturated or aromatic,

iii) esters -COOR ¹¹ , alkoxide -OR ¹² , and / or phosphonate -PO (OR ¹³ ) ₂ , wherein R ¹¹ , R ¹² or R ¹³ are radicals from the group ii).

Compounds of formula (Va) or (Vb) may also be attached to any class of polymer chains (primarily such that one or more of the above-mentioned radicals may constitute this class of polymer chains), and thus the polyacrylate PSA Can be used for synthesis.

Most preferably, controlled regulators for the polymerization of the following types of compounds are used:

● 2,2,5,5-tetramethyl-1-pyrrolidinyloxyl (PROXYL), 3-carbamoyl-PROXYL, 2,2-dimethyl-4,5-cyclohexyl-PROXYL, 3-oxo-PROXYL , 3-hydroxyimine-PROXYL, 3-aminomethyl-PROXYL, 3-methoxy-PROXYL, 3-t-butyl-PROXYL, 3,4-di-t-butyl-PROXYL,

2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO), 4-benzoyloxy-TEMPO, 4-methoxy-TEMPO, 4-chloro-TEMPO, 4-hydroxy-TEMPO, 4 Oxo-TEMPO, 4-amino-TEMPO, 2,2,6,6-tetraethyl-1-piperidinyloxyl, 2,2,6-trimethyl-6-ethyl-1-piperidinyloxyl,

N-tert-butyl 1-phenyl-2-methylpropyl nitroxide,

N-tert-butyl 1- (2-naphthyl) -2-methylpropyl nitroxide,

N-tert-butyl 1-diethylphosphono-2,2-dimethylpropyl nitroxide,

N-tert-butyl 1-dibenzylphosphono-2,2-dimethylpropyl nitroxide,

N- (1-phenyl-2-methylpropyl) 1-diethylphosphono-1-methylethyl nitroxide,

Di-tert-butyl nitroxide,

Diphenyl nitroxide,

Tert-butyl tert-amyl nitroxide.

Another series of polymerization processes in which PSA can be prepared by alternative processes can be selected from the prior art:

US 4,581,429A describes a controlled-growth free-radical polymerization process using the formula R'R "NOY as an initiator, wherein Y is a free-radical species capable of polymerizing unsaturated monomers. The reaction has a low conversion rate A specific problem is the polymerization of acrylates, which are carried out in very low yields and in molar mass WO 98 / 13392A1 describes open-chain alkoxyamine compounds with symmetrical substitution patterns. EP 735 052 A1 describes a process for producing thermoplastic elastomers having a narrow molar mass distribution WO 96/24620 A1 describes very particular free-radical compounds, for example phosphorus-containing nitroxide based imidazolines Dean describes the polymerization process in which WO 98/44008 A1 describes morpholines, piperazinone and piperazindi based on particular nitroxyls. DE 199 49 352 A1 describes heterocycle alkoxyamines as modulators in controlled-growth free-radical polymerizations Another development of the corresponding alkoxyamines or the corresponding free nitroxides is polyacrylics. Improve the efficacy for preparing the rate [Hawker, Contribution to the National Meeting of the American Chemical Society, Spring 1997; Husemann, Contribution to the IUPAC World-Polymer Meeting 1998, Gold Coast].

As another controlled polymerization process, atom transfer radical polymerization (ATRP) can be advantageously used to synthesize polyacrylate PSAs, in which case mono- or di-functional secondary or tertiary agents are preferably used as initiators. Primary halides are used, and complexes of Cu, Ni, Fe, Pd, Pt, Ru, Os, Rh, Co, Ir, Ag or Au are used to extract halides (EP 0 824 111 A1; EP 826 698 A1; EP 824 110 A1; EP 841 346 A1; EP 850 957 A1). Various possibilities of ATRP are further described in the specifications US 5,945,491 A, US 5,854,364 A, and US 5,789,487 A.

Coating process, treatment of carrier material

For production, in one preferred embodiment, the pressure sensitive adhesive is coated onto a carrier material from solution. In order to improve the fixation of the PSA, layer (a) may optionally be pretreated. The pretreatment can thus be carried out, for example, by corona or plasma.

To coat the PSA from the solution, heat is supplied, for example, to a dry tunnel to remove the solvent and initiate the crosslinking reaction, if appropriate.

The polymer described above may furthermore be coated as a hotmelt system (ie from a melt). Therefore, for the manufacturing process, it is possible to essentially remove the solvent from the PSA. In this case, any technique known to those skilled in the art can be used. One highly preferred technique is to concentrate using a single-screw or twin-screw extruder. The twin-screw extruder can be operated to co-rotate or counter-rotate. The solvent or water is preferably distilled off in two or more vacuum stages. Counterheating is also performed depending on the distillation temperature of the solvent. The fraction of remaining solvent is preferably less than 1%, more preferably less than 0.5%, and very preferably less than 0.2%. Further processing of the hot melt is carried out from the melt.

In order to coat with hot melt, different coating methods can be used. In one advantageous embodiment, the PSA is coated by a roll coating method. Different roll coating methods are described in "Handbook of Pressure Sensitive Adhesive Technology" by Donatas Satas (van Nostrand, New York 1989). In another embodiment, the coating is performed through a melt die. In another preferred process, the coating is carried out by extrusion. Extrusion coating is preferably carried out using an extrusion die. The extrusion die used is advantageous to use one of three classes: T-die, fishtail die and hanger die. The individual types differ in the design of their flow channels.

Through the coating, the PSA can also be directed.

In addition, the PSA may be essentially crosslinked. In one preferred embodiment, the crosslinking is carried out thermally with electron beams and / or UV rays.

UV crosslinking irradiation is performed by short wavelength ultrasonic irradiation in the wavelength range of 200 to 400 nm depending on the UV photoinitiator used; In particular the irradiation is carried out using a high pressure or medium pressure mercury lamp with an output of 80 to 240 W / cm. Irradiation intensity is controlled by the individual quantum yield and set crosslinking of the UV photoinitiator.

Moreover, in one advantageous embodiment of the invention, the PSA is crosslinked using an electron beam. Conventional irradiation equipment that may advantageously be used includes linear cathode systems, scanner systems, and segmented cathode systems, where an electron beam accelerator is used. Detailed description of the art and the most important process parameters are described in Skelhorne, Electron Beam Processing, in Chemistry and Technology of UV and EB formulation for Coatings, Inks and Paints, Vol. 1, 1991, SITA, London. Typical acceleration voltages are in the range of 50 kV to 500 kV, preferably 80 kV to 300 kV. The scatterer doses used are 5 to 150 kGy, in particular 20 to 100 kGy.

In addition, both crosslinking methods or other methods of performing high energy irradiation can be used.

The present invention also provides the use of the double-sided pressure-sensitive adhesive tape of the present invention for adhesive bonding or production of LC displays. For use as a pressure sensitive adhesive tape, the double sided pressure sensitive adhesive tape may be lined with one or two release films or release papers. In one preferred embodiment, a siliconized or fluorinated film or paper, such as glassine, HDPE or LDPE coated paper, is used, which provides a release coat based on a silicone or fluorinated polymer. One particularly preferred embodiment uses a siliconized PET film for lining.

The pressure-sensitive adhesive tapes of the present invention are particularly advantageous for adhesive bonding of light-emitting diodes (LEDs) as light sources for LCD modules.

Example

The invention is described below, which does not require any unnecessary limitations as a result of the choice of examples.

The following test method was used.

Test Methods

A. Transmittance

Transmittance was measured in the wavelength range from 190 to 900 nm using Uvikon 923 from Biotek Kontron. The measurement was performed at 23 ° C. Absolute transmission is described as a% value at 550 nm compared to complete light absorption (0% transmission = no light transmission; 100% transmission = complete light transmission).

B. Pinhole

Full light shielding masking was provided to commercially common types of very powerful light sources (eg, Liesegangtrainer 400 KC Type 649 Overhead Projector, 36 V Halogen Lamp, 400 W). Such a mask contains an annular perforation with a diameter of 5 cm at its center. A double sided LCD adhesive tape was placed on top of the annular perforation. In a completely dark environment, the number of pinholes was counted electronically or visually. When the light source is turned on, these pinholes are seen as translucent points.

C. Reflectance

Reflection tests were performed according to DIN Standard 5036 Part 3, and DIN 5033 Part 3 and DIN 5033 Part 4. The instrument used is an LMT-type Ulbricht sphere (50 cm in diameter) incorporating an LMT-type Tau-ρ-meter digital display device. Integrated measurements were made using a light source corresponding to standard light A and a V (λ) -modified Si optical device. Measurements were made on glass reference samples. Reflectance is described as the sum of the% fraction of direct light and scattered light.

Polymer 1

A conventional 200 L reactor was charged with 2400 g of acrylic acid, 64 kg of 2-ethylhexyl acrylate, 6.4 kg of methyl acrylate and 53.3 kg of acetone / isopropanol (95: 5) for free-radical polymerization. After passing the reactor for 45 minutes with stirring of nitrogen gas, the reactor was heated to 58 ° C. and 40 g of 2,2′-azoisobutyronitrile (AIBN) was added. The external heating bath was then heated to 75 ° C. and the reaction was carried out constantly at this external temperature. After 1 hour reaction time, 40 g of AIBN was further added. After 5 and 10 hours, dilution was performed with 15 kg of acetone / isopropanol (95: 5) at each hour. After 6 and 8 hours, 100 g of dicyclohexyl peroxydicarbonate (Perkadox 16®, Akzo Nobel) in 800 g of acetone was added at each hour. After the reaction time of 24 hours the reaction was terminated and the reaction mixture was cooled to room temperature. Before using the composition for coating, Polymer 1 was diluted to 30% solids content with isopropanol. Thereafter, 0.3% by weight of aluminum (III) acetylacetonate (3% strength solution, isopropanol) based on polymer 1 was mixed with polymer 1 with vigorous stirring.

Film (Al Vapor Coating):

12 μm or 38 μm thick PET film (12 μm is for example Hostaphan ™ from Mitsubishi; 38 μm is for example Lumirror ™ 38E20 from Toray) on one side until the aluminum layer is applied to the entire area Or steam-coated with aluminum on both sides. The film was steam-coated to a width of 300 mm by the sputtering process. Here, positively charged ionized argon gas was passed through a high vacuum chamber. The charged ions then strike the negatively charged Al plate, release particles of aluminum at the molecular level, and then deposit on the polyester film passing over the plate.

Coating materials 1

In a Red Devil paint mixer, 42 parts Acrydic A-109 (nitrogen-containing acrylic resin with 50% solids content from Dainippon Ink and Chemicals), 80 parts titanium white JR603 (Teikoku Kako Co. Ltd.) , 6 parts xylene, 6 parts toluene and 6 parts methyl ether ketone were dispersed for 30 minutes. It was then homogenized in Ultraturrax.

Example 1:

Coating composition 1 was uniformly applied to a 12 μm PET film aluminized on both sides using a Meyer bar, and the applied coating was dried at 120 ° C. for 10 minutes. The coating weight is 10 g / m 2.

Polymer 1 was then evenly applied to this coat as a solution and dried at 100 ° C. for 10 minutes. The coat weight for this coat is 50 g / m 2. The sides were lined with a 50 μm thick double sided siliconized PET film. On the other side, Polymer 1 was evenly applied at 50 g / m 2 and dried again at 100 ° C. for 10 minutes.

Example 2

Apply coating composition 1 uniformly to the non-metalized side of a 35 μm PET film extruded with a white pigment as a filler and aluminized from one side from Toray (Lumirror ™ 38E20) using a Meyer bar And the applied coating was dried at 120 ° C. for 10 minutes. The coating weight is 10 g / m 2.

Polymer 1 was then evenly applied to this coat as a solution and dried at 100 ° C. for 10 minutes. The coat weight for this coat is 50 g / m 2. The sides were lined with a 50 μm thick double sided siliconized PET film. On the opposite side (metal side), polymer 1 was evenly applied at 50 g / m 2 and dried again at 100 ° C. for 10 minutes.

Example 3

Coating composition 1 was uniformly applied to the unmetalized side of the 12 μm PET film using a Meyer bar and the applied coating was dried at 120 ° C. for 10 minutes. The application weight is 12 g / m 2.

Polymer 1 was then evenly applied to this coat as a solution and dried at 100 ° C. for 10 minutes. The coat weight for this coat is 50 g / m 2. The sides were lined with a 50 μm thick double sided siliconized PET film. On the other side, Polymer 1 was evenly applied at 50 g / m 2 and dried again at 100 ° C. for 10 minutes.

Example 4:

Apply coating composition 1 uniformly to the non-metalized side of a 35 μm PET film extruded with a white pigment as a filler and aluminized from one side from Toray (Lumirror ™ 38E20) using a Meyer bar And the applied coating was dried at 120 ° C. for 10 minutes. The application weight is 15 g / m 2.

Polymer 1 was then evenly applied to this coat as a solution and dried at 100 ° C. for 10 minutes. The coat weight for this coat is 50 g / m 2. The sides were lined with a 50 μm thick double sided siliconized PET film. On the other side, Polymer 1 was evenly applied at 50 g / m 2 and dried again at 100 ° C. for 10 minutes.

result

Example 1 is an example of the present invention using two metal layers for light absorption and light reflection.

Examples 2 to 4 use only one metal surface for light reflection.

Examples 1 and 3 are examples using thin transparent films, and Examples 2 and 4 are examples using relatively thick white PET films.

Examples 1-4 were tested according to test methods A, B and C. The results are shown in Table 1 below.

Example Transmittance (test A) Pinhole (test B) Reflectance (total) silver plane (test C) Reflectivity (total) white side (test C) Example 1 <0.1% 0 86.2% 70.8% Example 2 <0.1% 0 86.3% 72.6% Example 3 1.3% 0 86.2% 71.1% Example 4 <0.1% 0 86.0% 73.3%

From the results of Table 1, it can be seen that Examples 1 to 4 have excellent properties in terms of optical defects (absence of pinholes) and transmittance. In connection with Test C, moreover, Examples 1-4 have been shown to have not only light-absorbing properties but also very high light-reflecting properties. In terms of silver reflection, in particular more than 85% reflectance was obtained. However, even on the white side, more than 70% reflectance was obtained, but the diffuse light fraction was higher here.

For the application of LCDs, this means that the light yield in the light channel is significantly increased. In addition, it is absolutely essential to use a double-sided pressure-sensitive adhesive tape that must be black on one side and light-reflective (ie white or metallic) on the other side for the production of light-reflective and light-absorbing tapes. no.

Claims (9)

Especially for producing or adhesively bonding optical liquid crystal data displays (LCDs) having a carrier film having light-reflecting and light-absorbing properties, having a top side and a bottom side, and additionally having a top side and a bottom side in turn. A pressure-sensitive adhesive tape, wherein the pressure-sensitive adhesive tape has a pressure-sensitive adhesive layer on both sides, at least a metal layer between the pressure-sensitive adhesive layer on the lower surface of the pressure-sensitive adhesive tape and the carrier film, and at least between the pressure-sensitive adhesive layer on the upper surface of the pressure-sensitive adhesive tape and the carrier film. Pressure-sensitive adhesive tape, characterized in that it has a white coating layer. The pressure-sensitive adhesive tape of claim 1, wherein the pressure-sensitive adhesive tape has a second metal layer between the pressure-sensitive adhesive layer on the upper surface of the pressure-sensitive adhesive tape and the carrier film. 3. The pressure-sensitive adhesive tape of claim 2, wherein the second metal layer is between the carrier film and the white coating layer. The pressure-sensitive adhesive tape according to any one of claims 1 to 3, wherein at least one of the pressure-sensitive adhesive layers is transparent. The pressure-sensitive adhesive tape according to any one of claims 1 to 4, wherein at least one of the pressure-sensitive adhesive layers is colored white. The pressure-sensitive adhesive tape according to any one of claims 1 to 5, wherein the carrier film is transparent. Use of the pressure sensitive adhesive tape of claim 1 for producing or adhesively bonding an optical liquid crystal data display. 8. Use according to claim 7, for adhesively bonding LCD glass. A liquid crystal data display device comprising the pressure-sensitive adhesive tape of any one of claims 1 to 6.

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