EP1828337A1

EP1828337A1 - Double-sided adhesive tapes for producing lc displays having light-reflecting and absorbing properties

Info

Publication number: EP1828337A1
Application number: EP05823588A
Authority: EP
Inventors: Marc Husemann; Reinhard Storbeck
Original assignee: Tesa SE
Current assignee: Tesa SE
Priority date: 2004-12-02
Filing date: 2005-12-02
Publication date: 2007-09-05
Also published as: CN101068898A; DE102004058279A1; WO2006058910A1; TW200628581A; US20090123667A1; JP2008521989A; DE112005002879A5; KR20070092254A

Abstract

The invention relates to an adhesive tape, especially for producing or gluing optical liquid crystal displays (LCDs). Said tape comprises a lower face and an upper face, the lower face having light-reflecting properties and the upper face having light-absorbing properties, a support film having an upper face and a lower face, said adhesive tape being provided on both sides with an adhesive layer. The inventive tape is characterized in that the support film has a content of antiblocking agents of less than 4000 ppm, the support film is brightly colored and at least one light-absorbing chromophoric layer is provided at least between the lower face of the support film and the adhesive layer disposed on said face.

Description

tesa Aktiengesellschaft Hamburg

description

Double-sided pressure-sensitive adhesive tapes for the production of LC displays with light-reflecting and absorbing properties

The invention relates to double-sided pressure-sensitive adhesive tapes with multilayer carrier structures and with light-reflecting and absorbing properties for the production of liquid-crystal data displays (LCDs).

Pressure sensitive adhesive tapes are widely used processing aids in the age of industrialization. Especially for use in the computer industry very high demands are placed on pressure-sensitive adhesive tapes. In addition to a small one

Outgassing behavior, the PSA tapes should be used in a wide temperature range and meet certain optical properties.

A field of application are LCD displays that are needed for computers, televisions, laptops, PDAs, mobile phones, digital cameras, etc. A very common type of LCD

Module for such applications is shown in Fig. 1.

Fig. 1 shows the concept of a double-sided adhesive tape with a black absorption layer and a white reflection layer according to the prior art; where:

1 LCD glass 8 reflection foil

2 double-sided black and white 9 LCD case

Tape 10 black absorbent

3 pressure-sensitive adhesive tape side

4 light source (LED) 11 white reflective side

5 light beams 12 visible area

6 double-sided tape 13 "blind" area

7 light guides To produce LC displays, LEDs are glued as a light source to the LCD glass. For this purpose, black double-sided pressure-sensitive adhesive tapes are often used. The purpose of the black coloring is to ensure that no light penetrates from the inside to the outside and vice versa in the region of the double-sided pressure-sensitive adhesive tape. There are already many concepts to achieve such a black color.

On the other hand, one would like to increase the light efficiency of the rear light module, so that preferably double-sided adhesive tapes are used which are black on one side (light-absorbing) and light-reflecting on the other side. There are also many concepts for producing the black page.

A concept for the production of black double-sided pressure-sensitive adhesive tapes is the coloring of the carrier material. In the electronics industry, very preferably double-sided pressure-sensitive adhesive tapes with polyester film supports (primarily polyethylene terephthalate, PET) are used, since they can be punched very well. The PET supports can also be dyed with carbon black or black color pigments to achieve absorption of the light. The disadvantage of this concept is the low absorption of the light. In very thin carrier layers, only a relatively small number of carbon black or other black pigment particles can be introduced, with the result that no complete absorption of the light is achieved. With the eye and also with more intense light sources (light intensity greater than 600 candela) then the lack of absorption can be determined.

Another concept for producing black double-sided pressure-sensitive adhesive tapes relates to the production of a two-layered support material by means of coextrusion. Carrier films are usually produced by extrusion. Coextrusion coextrudes, in addition to the conventional support material, a second black layer which fulfills the function of light absorption. This concept also has several disadvantages. For example, anti-blocking agents must be used for the extrusion, which then lead to the so-called pinholes in the product. These pinholes are optical defects (light transmission at these holes) and negatively affect the operation in the LCD. By blocking (or blocking), one understands the undesirable property of plastic films and the like to adhere to one another above a certain temperature (block point) even with only slight pressure. Blocking is countered with anti-blocking agents (antiblocking agents, antiblocking agents). Anti-blocking agents are thus substances that the bonding (blocking, blocking) z. B. reduce or prevent thermoplastic polymer films with themselves or other materials by cold flow or electrostatic charging. Normally, for example, silicon dioxide (eg silica particles), chalk or chalk, zeolites are used for the production process of, for example, PET films as anti-blocking agents.

Anti-blocking agents are intended to prevent the caking of flat plastic films under pressure and temperature to form blocks. Usually, the antiblocking agents are incorporated into the thermoplastic mixture. The particles then act as spacers.

Another problem is the layer thicknesses, since the two layers are first formed individually in the nozzle and thus can be realized in total only relatively thick carrier layers, with the result that the film is relatively thick and inflexible and thus to the surfaces to be bonded only still badly fits. In addition, the black layer must also be relatively thick, otherwise no complete absorption can be realized. Another disadvantage is the changed mechanical properties of the carrier material, since the black layer has different mechanical properties to the original carrier material (eg pure PET). Another disadvantage for the two-layer version of the carrier material is the different anchoring of the adhesive on the coextruded carrier material. For this case of the design, there is always a weak spot in the double-sided adhesive tape.

In another concept, a black color coat is coated on the support material. This can be done on one or both sides of the carrier. This too

Concept has several disadvantages. On the one hand, it is easy to do this too

Defects (pinholes), which are registered by anti-blocking agent during the film extrusion process. These are not acceptable for final use in the LC display. Furthermore, the maximum absorption properties do not meet the requirements, since only relatively thin paint layers can be applied. Here, too, one is limited in the layer thicknesses upwards, since otherwise the mechanical properties of the carrier material would change. There is a trend in the development of LC displays. On the one hand, LC displays are to become lighter and flatter, and there is a growing demand for ever larger displays with ever higher resolution.

For this reason, the design of the displays has been changed and the light source moves accordingly closer to the LCD panel, with the consequence that the danger increases that more and more light from the outside penetrates into the edge zone of the LCD panel

("blind area") (see Figure 1). With this development, therefore, the

Requirements for the shading properties (black out properties) of the double-sided adhesive tape and there is thus a need for new concepts for the production of black adhesive tapes.

On the other hand, the double-sided adhesive tape should be reflective.

For this purpose, double-sided pressure-sensitive adhesive tapes are known which have on one side a white or a metallic layer and a black light-absorbing layer. With these pressure-sensitive adhesive tapes, significant improvement has been achieved in terms of light reflection on one side and absorption on the opposite side, but the anti-blocking agents in the support layer cause irregularities in the reflective side.

In general, double-sided pressure-sensitive adhesive tapes with a white and a black layer have process advantages over double-sided pressure-sensitive adhesive tapes with a metallic layer and a black layer, since black-metallic pressure-sensitive adhesive tapes or punched parts can easily exhibit kinks (which may also occur in positioning in the LCD) then directly negatively affect the reflective properties.

Some concepts for producing oil-absorbing and -Reflective double-sided pressure-sensitive adhesive tapes are proposed by patents. To achieve a reflective layer, the PSA may in turn be provided with reflective particles. The achievable reflective properties are only relatively insufficient.

JP 2002-350612 describes double-sided adhesive tapes for LCD panels with light-protective properties. The function is achieved by a metal layer applied on one or both sides of the carrier film, wherein additionally the carrier film can still be colored. However, the adhesive tapes described there have only this function and thus do not connect the light-absorbing function on one side and the light-reflecting function on the other side.

JP 2002-023663 also describes double-sided adhesive tapes for LCD panels with light-protection properties. Again, the function is achieved by a metal layer applied on one or both sides on the carrier film.

DE 102 43 215 describes double-sided adhesive tapes for LC displays with light-absorbing properties on the one hand and light-reflecting properties on the other hand. This patent describes black / silver double-sided pressure-sensitive adhesive tapes.

For the bonding of LCD displays or for their production thus there is still the need for double-sided pressure-sensitive adhesive tapes, which have the deficiencies described above, or only in a reduced manner.

The object of the invention is to provide a double-sided pressure-sensitive adhesive tape in which the influence of impurities (pinholes) in the application is avoided or reduced, and which is able to completely absorb light and reflect on the opposite side.

Surprisingly, it has been found that antiblocking agent-containing films for the production of certain double-sided pressure-sensitive adhesive tapes with light-absorbing and light-reflecting properties, as shown below, as

Carrier materials are suitable, this accessibility for this purpose for the skilled worker can not be further improved by suitable pretreatment, and the adhesive tapes thus obtained have the desired advantages over the prior art unexpectedly. In particular, surprisingly, no negative influence on the optical properties was found.

The invention thus relates to pressure-sensitive adhesive tapes, in particular those for the production of optical liquid-crystal data displays (LCDs), with an upper and a lower side, with light-reflecting properties on the upper side and light-absorbing Characteristics on the underside, comprising a carrier film having a top and a bottom, wherein the pressure-sensitive adhesive tape is provided on both sides with a pressure-sensitive adhesive layer, and wherein the carrier film has a content of anti-blocking agents of less than 4000 ppm, the carrier film is light colored and at least between the Bottom of the carrier film and the pressure-sensitive adhesive layer located on this side at least one light-absorbing ink-carrying layer is provided.

Anti-blocking agents in the sense of the invention may e.g. in particular silica particles, but also, for example, other silicas, chalk or chalk, zeolites.

The pressure-sensitive adhesive layers may be identical or different.

By reducing or completely eliminating the anti-blocking agents, the number of potential pinhole defects is reduced or eliminated. This is achieved by an anti-blocking agent content of <1000 ppm, preferably <500 ppm, very preferably of 0 ppm.

In an advantageous embodiment of the invention, we achieved the bright coloration of the carrier layer by the presence of white pigments.

The carrier film is preferably between 4 and 250 μm, more preferably between 8 and 50 μm, most preferably between 12 and 36 μm thick. It is brightly colored, preferably white, and of very low light transmission. Advantageously, the carrier film used is roughened on at least one side. The preferred roughness is preferably more than 50 nm and less than 400 nm, in particular less than 300 nm. The determination of the roughness can be done, for example, via AFM (atomic force microscope, Atomic Force Microscope). In this case, the roughness data are to be understood as RMS roughnesses. Furthermore, according to the invention advantageously, the film can be roughened on both sides, in which case both one side and both sides can show the above-mentioned advantageous roughness values.

On the underside of the carrier film may be provided a metallic reflective layer. This layer is preferably metallic shiny and reduces the light absorption of the inventive pressure-sensitive adhesive tape. It is advantageous in the metallic reflective layer around a metal coating. In a preferred embodiment of the invention, the carrier film is vapor-deposited on one side with metal, for example aluminum or silver, in particular advantageously via the sputtering process. The layer thickness of the metallically reflecting layer is preferably between 5 nm and 200 nm.

A second advantageous variant for producing the metallically reflecting layer is the application of a silver-colored coating.

At least one light-absorbing ink-carrying layer is provided between the underside of the carrier film and the pressure-sensitive adhesive layer located on this side. The color-carrying layer is in particular a lacquer layer which preferably has a layer thickness between 0.01 and 5 μm.

In addition to a first color-carrying layer, further color-bearing layers can be provided on both sides of the adhesive tape. Advantageously, this is also paint layers of the thickness specified above.

In a very preferred embodiment, at least one of the color-carrying layers is black, in particular the outermost color-carrying layer. The color-bearing layers can be of different chemical nature and can have different color-bearing pigments, which have an advantageous effect on the light-absorbing properties.

The pressure-sensitive adhesive layers preferably have a thickness of 5 μm to 250 μm in each case. Furthermore, it is part of the invention to select the individual layers within the double-sided pressure-sensitive adhesive tape independently of one another with regard to the layer thickness, so that e.g. different thickness PSA layers can be applied.

In the following, some advantageous embodiments of the pressure-sensitive adhesive tape according to the invention will be shown (FIGS. 2 and 3), without wishing to be unnecessarily limited by the choice of the illustrated examples. In the figures mean:

(a) Carrier film layer

(b) Metallic reflective layer

(c) (first) color-carrying layer (c ¹ ) further color-bearing layer (d) PSA layer (d ') PSA layer

In a first advantageous embodiment of the invention, the carrier film is dyed white and provided with a metallically reflective coating. Such

Pressure-sensitive adhesive tape is shown by way of example in FIG. 2. The inventive pressure-sensitive adhesive tape consists of a carrier film layer (a) with a high white color pigment content and with reduced or no anti-blocking agent, a metallic layer (b), a color-carrying layer (c) on the underside and two pressure-sensitive adhesive layers (d) and (d '), wherein the PSAs may be identical or different from each other.

In a second preferred embodiment of the invention, the inventive pressure-sensitive adhesive tape has the product structure shown in FIG. Here, the double-sided pressure-sensitive adhesive tape consists of a carrier film (a) with a high proportion of white pigment, with a reduced or no antiblocking agent, a metallic layer (b) on the underside, at least two color-coated layers (c) and (c ') coated on top of each other Underside and two pressure-sensitive adhesive layers (d) and (d ') (one on the top and the bottom), wherein the PSAs may be identical or different from each other.

In the following, the pressure-sensitive adhesive tapes of the invention will be described in more detail, wherein the description is not intended to be limited to the embodiments exemplified above.

In principle, all filmic polymer supports which can be dyed bright, in particular white, can be used as film carriers. Thus, for example, Polyethylene, polypropylene, polyimide, polyester, polyamide, polymethacrylate, fluorinated polymer films, etc. use. In a particularly preferred embodiment, polyester films are used, particularly preferably PET films (polyethylene terephthalate). The films may be relaxed or have one or more preferred directions. Preferred directions are achieved by stretching in one or two directions.

For the inventive pressure-sensitive adhesive tapes, films are used which contain no or only a very small proportion of anti-blocking agents. An example of such Film is eg the Hostaphan ™ 5000 series from Mitsubishi Polyester Film (PET 5211, PET 5333 PET 5210).

In particular for the production of very thin (for example 12 μm thick) PET films, it is very advantageous if the PET film is coated with metal and the film contains no or a significantly reduced proportion of anti-blocking agent. Particularly good results were obtained with respect to the avoidance of pinholes. Furthermore, 12 μm PET films are particularly advantageous because they allow very good adhesive properties for the double-sided adhesive tape, since the film is very flexible and can easily adapt to the surface roughness of the substrates to be bonded.

To improve the anchoring of the paint layers or metal vapor deposition, it is very advantageous to pretreat the films. The films may be etched (e.g., trichloroacetic acid or trifluoroacetic acid), pretreated with corona or plasma, or provided with a primer (e.g., saran).

Furthermore, the film contains color pigments and / or color-bearing particles. In principle, the colorants or particles familiar to the person skilled in the art are suitable for coloring the film. Pigments with very high throwing power are advantageously used. Advantageous examples of whitening are titanium dioxide pigments or particles or barium sulfate pigments or particles. The pigments or particles should advantageously be smaller in diameter than the final layer thickness of the carrier film. Optimal colorations can be achieved with 5 to 40 wt .-% of particles based on the film material.

The reflective and thus also light-absorbing layer can be a metallic, in particular silver-colored, lacquer layer on the foil, advantageously the reflective layer can also be produced by vapor deposition of the foil, in particular on one or both sides, with a metal, eg aluminum or silver. Preferably, the aluminum or silver is applied very evenly to the film. The use of the metallically reflecting layer, on the one hand, reflects the incident light and, on the other hand, reduces or avoids the transmission of the light through the carrier material. Furthermore, surface roughnesses of the carrier film can be compensated. The color-bearing layers can fulfill various functions. In an advantageous embodiment of the invention, the color layer has the function of the perfect absorption of the external light. In this case, the transmission for the double-sided pressure-sensitive adhesive tape in a wavelength range of 300-800 nm is <0.5%, more preferably <0.1%, most preferably <0.01%. In a preferred embodiment, this is achieved with a black lacquer layer as a color-carrying layer. Advantageously, the layer consists of a lacquer matrix (cured binder matrix, preferably thermosetting system, but also radiation-curing system possible), wherein color pigments are mixed into the lacquer matrix. As paint materials, for example, polyesters, polyurethanes, polyacrylates or polymethacrylates may be used in conjunction with the paint additives known to the person skilled in the art. In a highly preferred inventive embodiment, the color pigments are black; Carbon black or graphite particles are preferably mixed into the binder matrix as color-carrying particles. In addition to the complete light absorption, an electrical conductivity is additionally achieved by this addition at very high additive content (> 20% by weight), so that the inventive double-sided pressure-sensitive adhesive tapes likewise have antistatic properties.

To reinforce the absorbing property of the black color layer, which is preferably the outer of the color-carrying layers, a further, preferably further inside, color-carrying layer may also be provided with white color pigments. Titanium dioxide and / or barium sulfate pigments are preferably suitable as white color pigments.

In a preferred embodiment, the pressure-sensitive adhesive layers are identical on both sides of the pressure-sensitive adhesive tape of the invention. However, it may also be advantageous in a specific procedure if the pressure-sensitive adhesives of the top and the bottom side of the pressure-sensitive adhesive tape differ from one another with regard to the layer thickness and / or the chemical composition. Thus, for example, different adhesive properties can be set in this way. As pressure-sensitive adhesive systems for the inventive double-sided pressure-sensitive adhesive tape, acrylate, natural rubber, synthetic rubber, silicone or EVA adhesives are used. In the event that the reflection on the top of the pressure-sensitive adhesive tape should be very high, it should preferably have a high degree of transparency at least on this side of the pressure-sensitive adhesive tape. As PSAs it is in principle also possible to process the further PSAs known to the person skilled in the art.

For natural rubber adhesives, the natural rubber is not ground to a molecular weight (weight average) below about 100,000 daltons, preferably not below 500,000 daltons, and is additized.

For rubber / synthetic rubber as the starting material for the adhesive wide variations are given. Natural rubbers or synthetic rubbers or any blends of natural rubbers and / or synthetic rubbers can be used, the natural rubber or the natural rubbers in principle being made of all available qualities such as Crepe, RSS, ADS, TSR or CV types, depending according to required purity and viscosity level, and the synthetic rubber or the synthetic rubbers from the group of the random copolymerized styrene-butadiene rubbers (SBR), the butadiene rubbers (BR), the synthetic polyisoprenes (IR), the butyl rubbers (NR) , the halogenated butyl rubbers (XIIR), the acrylate rubbers (ACM), the ethylene-vinyl acetate copolymers (EVA) and the polyurethanes and / or their blends can be selected.

It is further preferable for rubbers to be added to improve the processability by adding thermoplastic elastomers having a weight fraction of from 10 to 50% by weight, based on the total elastomer content. Representative may be mentioned at this point especially the most compatible styrene-isoprene-styrene (SIS) and styrene-butadiene-styrene (SBS) types.

In an inventive preferred embodiment, acrylic PSAs and / or methacrylate adhesives are used.

(Meth) acrylate PSAs which are obtainable by radical polymerization consist of at least 50% by weight based on at least one acrylic monomer from the group of compounds of the following general formula:

wherein R ₁ = H or CH ₃ and the radical R ₂ = H or CH ₃ or is selected from the group of branched or unbranched, saturated alkyl groups having 1 to 30 carbon atoms.

The monomers are preferably chosen so that the resulting polymers can be used at room temperature or higher temperatures as pressure-sensitive adhesives, in particular such that the resulting polymers have pressure-sensitive adhesive properties.

In a further inventive design, the comonomer composition is selected such that the PSAs can be used as heat-activable PSAs.

The polymers can preferably be obtained by polymerization of a monomer mixture which is composed of acrylic acid esters and / or methacrylic acid esters and / or their free acids having the formula CH ₂ CHCH (R ₁ ) (COOR ₂ ), where R ₁ = H or CH ₃ and R _{2 is} an alkyl chain of 1-30 C atoms or H.

The molar masses (weight average) M _{w of} the polyacrylates used are preferably M _w > 200,000 g / mol.

In a very preferred manner, acrylic or methacrylic monomers are used which consist of acrylic and methacrylic acid esters having alkyl groups of 4 to 14 carbon atoms, preferably 4 to 9 carbon atoms. Specific examples, without wishing to be limited by this list, are methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, n-pentyl acrylate, n-hexyl acrylate, n-heptyl acrylate, n-octyl acrylate, n-octyl methacrylate, n-nonyl acrylate , Lauryl acrylate, stearyl acrylate, behenyl acrylate, and their branched isomers such as isobutyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, isooctyl acrylate, isooctyl methacrylate. Further classes of compounds to be used are monofunctional acrylates or methacrylates of bridged cycloalkyl alcohols, consisting of 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. Specific examples are cyclohexyl methacrylates, isobornyl acrylate, isobornyl methacrylates and 3,5-dimethyl adamantyl acrylate. In one approach, monomers are used, the polar groups such as carboxyl, sulfonic and phosphonic, hydroxy, lactam and lactone, N-substituted amide, N-substituted amine, carbamate, epoxy, thiol, alkoxy. Cyan radicals, ethers or the like wear.

Moderate basic monomers are N, N-dialkyl-substituted amides, such as N ₁ N-dimethylacrylamide, N, N-Dimethylmethylmethacrylamid, N-tert-butylacrylamide, N-vinylpyrrolidone, N-vinyllactam, dimethylaminoethyl methacrylate,

Dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, diethylaminoethyl acrylate, N-methylolmethacrylamide, N- (buthoxymethyl) methacrylamide, N-methylolacrylamide, N- (ethoxymethyl) acrylamide, N-isopropylacrylamide, but this list is not exhaustive.

Further preferred examples are 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, tetrahydrofufuryl acrylate, β-

Acryloyloxypropionsäure, trichloroacrylic acid, fumaric acid, crotonic acid, aconitic acid, dimethylacrylic acid, this list is not exhaustive.

In a further very preferred procedure, the monomers used are vinyl esters, vinyl ethers, vinyl halides, vinylidene halides, vinyl compounds having aromatic rings and heterocycles in the α-position. Here again, not only a few examples are mentioned: vinyl acetate, vinyl formamide, vinyl pyridine, ethyl vinyl ether, vinyl chloride, vinylidene chloride and acrylonitrile.

Furthermore, photoinitiators with a copolymerizable double bond can be used in an advantageous procedure. Norrish I and II photoinitiators are suitable as photoinitiators (Norrish type I reaction: photofragmentation (α-cleavage) of the carbonyl compound into an acyl radical and an alkyl radical; Norrish type II reaction : intramolecular abstraction of a hydrogen atom in the γ position of the carbonyl group, caused by the photochemically excited carbonyl group, resulting in a diradical that can decompose into an enol and an alkene (ß-cleavage) or cyclized to a cyclobutanol) , Examples are benzoin acrylate and a acrylated benzophenone from. UCB (Ebecryl ^® P 36). In principle, all photoinitiators known to those skilled in the art can be copolymerized, which can crosslink the polymer via UV irradiation via a radical mechanism.

In a further preferred procedure, monomers which have a high static glass transition temperature are added to the comonomers described. Suitable components are aromatic vinyl compounds, such as, for example, styrene, wherein the aromatic nuclei preferably consist of C ₄ - to cis units and may also contain heteroatoms. Particularly preferable examples are 4-vinylpyridine, N-vinylphthalimide, methylstyrene, 3,4-dimethoxystyrene, 4-vinylbenzoic acid, benzylacrylate, benzylmethacrylate, phenylacrylate, phenylmethacrylate, t-butylphenylacrylate, t-butylphenylmethacrylate, 4-biphenylacrylate and -methacrylate, 2-naphthylacrylate and methacrylate and mixtures of those monomers, this list is not exhaustive.

Increasing the aromatic content increases the refractive index of the PSA and minimizes scattering between LCD glass and PSA (e.g., extraneous light).

For further development, the PSAs may be mixed with resins. Suitable tackifying resins to be added are the tackifier resins known to the person skilled in the art. Mention may be made representative of the pinene, indene and rosin resins, their disproportionated, hydrogenated, polymerized, esterified derivatives and salts, the aliphatic and aromatic hydrocarbon resins, terpene resins and terpene phenolic resins and C5, C9 and other hydrocarbon resins. Any combination of these and other resins can be used to adjust the properties of the resulting adhesive as desired. In general, all compatible with the corresponding polyacrylate (soluble) resins can be used, in particular reference is made to all aliphatic, aromatic, alkylaromatic hydrocarbon resins, hydrocarbon resins based on pure monomers, hydrogenated hydrocarbon resins, functional hydrocarbon resins and natural resins.

Here, too, transparent and very well compatible with the polymer resins are preferably used to improve the transparency. Hydrogenated or partially hydrogenated resins often have these properties. In addition, plasticizers (plasticizers), further fillers (such as, for example, fibers, carbon black, zinc oxide, chalk, solid or hollow glass spheres, microspheres of other materials, silicic acid, silicates), nucleating agents, electrically conductive materials, such as, for example, conjugated polymers, may optionally be used , doped conjugated polymers, metal pigments, metal particles, metal salts, graphite, etc., blowing agents, compounding agents and / or anti-aging agents, for example in the form of primary and secondary antioxidants or in the form of light stabilizers.

In a further embodiment of the pressure-sensitive adhesive tape of the invention, the pressure-sensitive adhesive on the underside of the pressure-sensitive adhesive tape may also be coated with light-absorbing particles, such as e.g. black color pigments or carbon black or graphite particles, be added as a filler.

Furthermore, crosslinkers and promoters can be mixed for crosslinking. 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. Furthermore, thermally activatable crosslinkers, such as e.g. Lewis acid, metal chelates or multifunctional isocyanates may be added.

For optional crosslinking with UV light, UV-absorbing photoinitiators can be added to the PSAs. Useful photoinitiators which are very useful are benzoin ethers, such as benzoin ethers. B. benzoin methyl ether and benzoin isopropyl ether, substituted acetophenones, such as. B. 2,2-Diethoxyacetophenon (available as Irgacure 651 ^® from. Ciba Geigy ^® ), 2,2-dimethoxy-2-phenyl-1-phenylethanone, dimethoxyhydroxyacetophenone, substituted α-ketols, such as. For example, 2-methoxy-2-hydroxypropiophenone, aromatic sulfonyl chlorides, such as. For example, 2-naphthyl sulfonyl chloride, and photoactive oximes, such as. B. 1-phenyl-1,2-propanedione-2- (O-ethoxycarbonyl) oxime.

The above-mentioned and other usable photoinitiators and others of the type Norrish I or Norrish II may contain the following radicals: benzophenone, acetophenone, benzil, benzoin, hydroxyalkylphenone, phenylcyclohexylketone, anthraquinone, trimethylbenzoylphosphine oxide, methylthiophenylmorpholinketone, aminoketone , Azobenzoin, thioxanthone, hexarylbisimidazole, triazine or fluorenone, wherein each of these radicals may be additionally substituted with one or more halogen atoms and / or one or more alkyloxy groups and / or one or more amino groups or hydroxy groups.

The acrylate PSAs can be prepared as follows:

For the polymerization, the monomers are chosen so that the resulting polymers can be used at room temperature or higher temperatures as PSAs. In order to achieve a preferred glass transition temperature T _{G of} the polymers of T _G <25 ° C., the monomers are very preferably selected in accordance with the above, and the quantitative composition of the monomer mixture is advantageously selected such that according to the Fox equation (G1) ( See TG Fox, Bull. Am. Phys Soc., 1 (1956) 123) gives the desired T _G value for the polymer.

Y w _n

4- τ _G , _n (G1)

Here 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.

To prepare the poly (meth) acrylate PSAs, conventional free-radical polymerizations are advantageously carried out. Initiator systems which additionally comprise further free-radical initiators for the polymerization, in particular thermally decomposing radical-forming azo or peroxo initiators, are preferably used for the free-radical polymerizations. In principle, however, all acrylates customary to the person skilled in the art are suitable. The production of C-centered radicals is described in Houben Weyl, Methods of Organic Chemistry, Vol. E 19a, pp. 60-147. These methods are preferably applied by analogy. Examples of radical sources are peroxides, hydroperoxides and azo compounds, as some non-exclusive examples of typical free-radical initiators may be mentioned here potassium peroxodisulfate, dibenzoyl peroxide, cumene hydroperoxide, cyclohexanone peroxide, di-t-butyl peroxide, azodiisoic acid butyronitrile, cyclohexylsulfonyl acetyl peroxide, diisopropyl percarbonate, t-butyl peroctoate, benzpinacol. In a very preferred embodiment, 1, 1'-azobis (cyclohexanecarboxylic acid nitrile) (Vazo 88 ™ from DuPont) or azodisobutyronitrile (AIBN) is used as free-radical initiator.

The weight average molecular weights M _w of the PSAs formed in the free-radical polymerization are very preferably selected such that they are in a range from 200,000 to 4,000,000 g / mol; PSAs of average molecular weights M _{w of} from 400,000 to 1,400,000 g / mol are produced especially for further use as electrically conductive hotmelt PSAs with resilience. The determination of the average molecular weight is carried out by size exclusion chromatography (GPC) or matrix-assisted laser desorption / ionization mass spectrometry (MALDI-MS).

The polymerization may be carried out neat, in the presence of one or more organic solvents, in the presence of water or in mixtures of organic solvents and water. The aim is to keep the amount of solvent used as low as possible. Suitable organic solvents are pure alkanes (eg hexane, heptane, octane, isooctane), aromatic hydrocarbons (eg benzene, toluene, xylene), esters (eg ethyl acetate, propyl, butyl or hexyl acetate), halogenated hydrocarbons (eg chlorobenzene) , Alkanols (eg methanol, ethanol, ethylene glycol,

Ethylene glycol monomethyl ether) and ethers (e.g., diethyl ether, dibutyl ether) or mixtures thereof. The aqueous polymerization reactions can be treated with a water-miscible or hydrophilic cosolvent to ensure that the reaction mixture is in the form of a homogeneous phase during the monomer conversion. Advantageously used cosolvents for the present invention are selected from the following group consisting of aliphatic alcohols, glycols, ethers, glycol ethers, pyrrolidines, N-alkylpyrrolidinones, N-alkylpyrrolidones, polyethylene glycols, polypropylene glycols, amides, carboxylic acids and salts thereof, esters, organosulfides, Sulfoxides, sulfones, alcohol derivatives, hydroxy ether derivatives, aminoalcohols, ketones and the like, as well as derivatives and mixtures thereof.

The polymerization time is - depending on the conversion and temperature - between 2 and 72 hours. The higher the reaction temperature can be chosen, that is, the higher the thermal stability of the reaction mixture, the lower the reaction time can be selected.

To initiate the polymerization, the entry of heat is essential for the thermally decomposing initiators. The polymerization can be initiated for the thermally decomposing initiators by heating to 50 to 160 ° C, depending on the type of initiator.

For the preparation, it may also be advantageous to polymerize the (meth) acrylate PSAs in substance. In particular, the Präpolymerisationstechnik is suitable here. The polymerization is initiated with UV light, but only to a low conversion about 10 - 30% out. Subsequently, this polymer syrup may e.g. are shrink-wrapped in films (in the simplest case ice cubes) and then polymerized in water to high sales. These pellets can then be used as acrylate hotmelt adhesives, with film materials which are compatible with the polyacrylate being used with particular preference for the melting process. Also for this preparation method, the thermally conductive material additives can be added before or after the polymerization.

Another advantageous preparation process for the poly (meth) acrylate PSAs is anionic polymerization. Here, inert solvents are preferably used as the reaction medium, e.g. aliphatic and cycloaliphatic hydrocarbons, or aromatic hydrocarbons.

The living polymer in this case is generally represented by the structure P _L (A) -Me, where Me is a Group I metal such as lithium, sodium or potassium, and P _L (A) is a growing polymer of the acrylate monomers , The molecular weight of the polymer to be produced is increased by the ratio of initiator concentration

Monomer concentration controlled. Suitable polymerization initiators are, for. As n-propyllithium, n-butyllithium, sec-butyllithium, 2-naphthyllithium, cyclohexyllithium or octyllithium, this list is not exhaustive.

Furthermore, initiators based on samarium complexes for the polymerization of

Acrylates known (Macromolecules, 1995, 28, 7886) and can be used here.

Furthermore, it is also possible to use difunctional initiators, for example 1,1,1,4,4-tetraphenyl-1,4-dilithiobutane or 1,1,1,4,4-tetraphenyl-1,4-dilithioisobutane. Co-initiators can also be used. Suitable coinitiators include lithium halides, alkali metal alkoxides or alkylaluminum compounds. In a very preferred version, the ligands and coinitiators are selected so that acrylate monomers such as n-butyl acrylate and 2-ethylhexyl acrylate can be directly polymerized and need not be generated in the polymer by transesterification with the corresponding alcohol.

For the preparation of poly (meth) acrylate PSAs having a narrow molecular weight distribution, controlled radical polymerization methods are also suitable. For the polymerization, a control reagent of the general formula is then preferably used:

(I) (H)

wherein R ^§ and R ^{# are} independently selected or the same - branched and unbranched d- to Ci ₈ alkyl radicals; C ₃ to C ₈ alkenyl radicals; C ₃ to Cis alkynyl radicals;

Cr to cis alkoxy residues

- By at least one OH group or a halogen atom or a silyl ether substituted C _r to Ci ₈ alkyl radicals; C ₃ to C ₈ alkenyl radicals; C ₃ to C ₈ -alkynyl radicals;

C ₂ -C ₈ -Hetero-alkyl radicals having at least one O atom and / or one NR * -

Group in the carbon chain, where R * can be any (especially organic) radical having at least one ester group, amine group, carbonate group, cyano group, isocyano group and / or epoxy group and / or sulfur-substituted C _r

Cis-alkyl radicals, C ₃ -C ₈ -alkenyl radicals, C ₃ -C ₈ -alkynyl radicals;

- C ₃ -Ci ₂ -cycloalkyl radicals C ₆ -C ₈ - aryl or benzyl radicals

- Represent hydrogen. Control reagents of type (I) preferably consist of the following further restricted compounds:

Halogen atoms are in this case preferably F, Cl, Br or I, more preferably Cl and Br. Als

Alkyl, alkenyl and alkynyl radicals in the various substituents are outstandingly suitable for both linear and branched chains.

Examples of alkyl radicals containing 1 to 18 carbon atoms are methyl, ethyl,

Propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, 2-pentyl, hexyl, heptyl, octyl, 2-

Ethylhexyl, t-octyl, nonyl, decyl, undecyl, tridecyl, tetradecyl, hexadecyl and octadecyl.

Examples of alkenyl radicals having 3 to 18 carbon atoms are propenyl, 2-butenyl, 3-butenyl, isobutenyl, n-2,4-pentadienyl, 3-methyl-2-butenyl, n-2-octenyl, n-2-dodecenyl,

Isododecenyl and oleyl.

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

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

Examples of halogen-substituted alkyl radicals are dichlorobutyl, monobromobutyl or

Trichlorohexyl.

A suitable C ₂ -C ₈ -Hetero-alkyl radical having at least one O atom in the

Carbon chain is, for example, -CH ₂ -CH ₂ -O-CH ₂ -CH ₃ . As C ₃ -C ₂ cycloalkyl radicals, for example, cyclopropyl, cyclopentyl, cyclohexyl or trimethylcyclohexyl serve.

As C ₆ -C ₈ -aryl radicals serve, for example, phenyl, naphthyl, benzyl, 4-tert-butylbenzyl or other substituted phenyl, such as ethyl, toluene, xylene, mesitylene, isopropylbenzene,

Dichlorobenzene or bromotoluene. The listings above are only examples of the respective ones

Connection groups and are not exhaustive.

Furthermore, compounds of the following types can also be used as control reagents

(IM) (IV) where R ^§ and R ^{# have} the meanings given above and R ^{1 can} also be selected independently of R ^§ and R ^# from the group listed above for these radicals.

The conventional 'RAFT process' usually polymerizes only to low conversions (compare WO 98/01478 A1) in order to realize the narrowest possible molecular weight distributions. Due to the low conversions, however, these polymers can not be used as pressure-sensitive adhesives and in particular not as hotmelt PSAs, since the high proportion of residual monomers adversely affects the adhesive properties, the residual monomers in the concentration process contaminate the solvent recycled and the corresponding self-adhesive tapes show a very high outgassing behavior. In order to avoid this disadvantage of lower conversions, in a particularly preferred procedure the polymerization is initiated several times.

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

(Va) (Vb)

wherein R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ independently represent the following compounds or atoms: i) halides, such as chlorine, bromine or iodine ii) linear, branched, cyclic and heterocyclic hydrocarbons having 1 to 20

Carbon atoms which may be saturated, unsaturated or aromatic, iii) esters -COOR ¹¹ , alkoxides -OR ¹² and / or phosphonates -PO (OR ¹³ J ₂ , where R ¹¹ , R ¹² or R ^{13 are} radicals from group ii) stand. Compounds of (Va) or (Vb) may also be bonded to polymer chains of any kind (primarily in the sense that at least one of the above radicals represents such a polymer chain) and thus be used for the construction of polyacrylate PSAs. More preferably, controlled regulators are used for the polymerization of compounds of the type:

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

2,2,6,6-tetramethyl-i-piperidinyloxy (TEMPO), 4-benzoyloxy-TEMPO, 4-methoxy-TEMPO, 4-chloro-TEMPO, 4-hydroxy-TEMPO, 4-oxo-TEMPO, 4- Amino-TEMPO, 2,2,6,6, -tetraethyl-i-piperidinyloxy, 2,2,6-trimethyl-6-ethyl-1-piperidinyloxy

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-t-butyl nitroxide • diphenyl nitroxide

• t-butyl-t-amyl nitroxide

A number of other polymerization methods, according to which the PSAs can be prepared in an alternative procedure, can be selected from the prior art:

No. 4,581,429 A discloses a controlled-free radical polymerization process which uses as initiator a compound of the formula R'R "NOY in which Y is a free-radical species capable of polymerizing unsaturated monomers, but the reactions generally have low conversions WO 98/13392 A1 describes open-chain alkoxyamine compounds which have a symmetrical substitution pattern EP 735 052 A1 discloses a process for the preparation of thermoplastic elastomers having narrow molecular weight distributions WO 96/24620 A1 describes a polymerization process employing very specific radical compounds such as phosphorus-containing nitroxides based on imidazolidine 98/44008 A1 discloses specific nitroxyls based on morpholines, piperazinones and piperazinediones. DE 199 49 352 A1 describes heterocyclic alkoxyamines as regulators in controlled free-radical polymerizations. Corresponding developments of the alkoxyamines or of the corresponding free nitroxides improve the efficiency for the preparation of polyacrylates.

As a further controlled polymerization method can be used advantageously for the synthesis of the polyacrylate PSA atom transfer radical polymerization (ATRP), wherein as initiator preferably monofunctional or difunctional secondary or tertiary halides and for the abstraction of the (r) halide (s) Cu, Ni , Fe, Pd, Pt, Ru, Os, Rh, Co, Ir, Ag or Au complexes (EP 0 824 111 A1, EP 826 698 A1, EP 824 110 A1, EP 841 346 A1, EP 850 957 A1). The different possibilities of ATRP are further described in US Pat. Nos. 5,945,491, 5,854,364 and 5,789,487.

The invention further relates to a method for producing double-sided adhesive tapes, in particular for use in LCD production or LCD bonding. The method is characterized by the use of a carrier film as already described above without or with a low proportion of blocking agents. Such films are not or poorly processable by known methods. Surprisingly, it has been found that anti-blocking agents or films can be made manageable for use in the pressure-sensitive adhesive tapes as described above when the films are coated on temperature-resistant process films on which the film (eg PET film) can cool before being wound up. In a variant of the method according to the invention, the temperature-resistant process foil is wrapped with. A blocking of the film (caking of the individual layers) can thus be avoided without the optical properties of the film change adversely. Furthermore, it has surprisingly been found that a low-anti-blocking agent or free film can also be further processed into the desired pressure-sensitive adhesive tapes and at the same time offers the properties desired for the pressure-sensitive adhesive tapes if the carrier film has been roughened before the pressure-sensitive adhesive tape is produced, in particular roughened such that it has a roughness of less than 400 nm, preferably of less than 300 nm, and preferably of more than 50 nm (data as RMS roughnesses). The roughness can advantageously be achieved by nanoimprinting, for example by a lamination process ("entrapment") in which a fleece and / or a fabric is pressed onto the surface of the film An advantageous lamination station consists of at least two rolls between which the desired contact pressure is generated Between the rollers, the web or the fabric is then laminated to the film, thereby transferring its surface structure to the film.

In a second variant of the method according to the invention, the surface structure is produced by the surface of one of the rollers itself on the surface of the film. By polishing processes, the microroughness of the film surface can be finely adjusted by choosing a suitable polish. In this case, several polishing operations can be provided in succession.

To improve the adhesion of the following layers to the film, it can be pretreated before or after roughening by etching, by treatment with corona or plasma and / or by finishing with a primer.

In a further development, the processes described above, in particular the coating on temperature-resistant process films and the roughening, are combined and both carried out in the process sequence according to the invention.

A very preferred process variant for the production of a reflective layer on the film is the one or two-sided vapor deposition of the film with a metal, e.g. Aluminum or silver. In order to achieve particularly excellent reflective and light-absorbing properties, it is advantageous to work by means of the sputtering process, the sputtering process being advantageously controlled so that the aluminum or silver is applied very uniformly. This leads to an optimal reflection of the vapor-deposited film (avoidance of scattering effects). Furthermore, in a very preferred embodiment, the PET film is vapor-coated on one side or on both sides with aluminum in one working step.

In an alternative procedure, a metallic coating, advantageously a silver-colored coating, is applied as the reflective layer. For this purpose, in particular a binder matrix is mixed with silver-colored color pigments. Aöls binder matrix are, for example, polyurethanes or polyesters which have a high refractive index and high transparency. With another Approach, the color pigments can be incorporated in a polyacrylate or polymethacrylate matrix and then cured as a lacquer. Through the use of the reflective layer, the light is specifically reflected on the one hand and, on the other hand, the transmission of the light through the carrier material is reduced.

In a further step, the color-bearing layers are applied. Advantageously, this layer can be obtained as follows: In a curing binder matrix (preferably thermosetting system, but also radiation-curing system possible), color pigments are mixed into the paint matrix, in particular black color pigments are selected. As varnish materials, e.g. Polyesters, polyurethanes, polyacrylates or polymethacrylates are used in conjunction with the paint additives known to those skilled in the art. In a highly preferred inventive embodiment, carbon black or graphite particles are mixed into the binder matrix as color-carrying particles. In addition to the complete light absorption, an electrical conductivity is additionally achieved by this addition at very high additive content (> 20% by weight), so that the inventive double-sided pressure-sensitive adhesive tapes likewise have antistatic properties.

For coating with PSAs, in a preferred procedure, the PSA is coated from solution onto the carrier film prepared in particular as described above (more precisely, applied to the carrier film applied on the carrier film

Layers). To increase the anchoring of the pressure-sensitive adhesive, it is optionally possible to pretreat the metallically reflecting layers and / or the ink-carrying layers. Thus, e.g. pretreated with corona or with plasma, it can be applied from the melt or from solution, a primer or it can be chemically etched.

Especially with a black lacquer layer but the corona performance should be minimized, since otherwise pinholes are burned into the film. For the coating of the PSA from solution, heat is applied via e.g. in a drying channel, the solvent is removed and optionally initiated the crosslinking reaction.

The polymers described above can furthermore also be coated as hotmelt systems (ie from the melt). For the production process, it may therefore be necessary to remove the solvent from the PSA. In principle, all methods known to those skilled in the art can be used here. A very preferred method is the concentration over a single or twin screw extruder. The twin-screw extruder can be operated in the same direction or in opposite directions. The solvent or water is preferably distilled off over several vacuum stages. In addition, depending on the distillation temperature of the solvent is heated counter. The residual solvent contents are preferably <1%, more preferably <0.5% and very preferably <0.2%. The hotmelt is processed from the melt.

For coating as a hotmelt different coating methods can be used. In one embodiment, the PSAs are coated by a roll coating process. Different roll coating processes are described in the Handbook of Pressure Sensitive Adhesive Technology by Donatas Satas (van Nostrand, New York 1989), in another embodiment a melt die is coated, in another preferred process extrusion is applied The extrusion dies used can advantageously come from one of the following three categories: T-die, fish-tail die and stirrup nozzle The individual types differ in the shape of their flow channel Orientation experienced.

Furthermore, it may be necessary for the PSA to be crosslinked. In a preferred embodiment, crosslinking is effected with electron and / or UV radiation.

For UV crosslinking is irradiated by short-wave ultraviolet irradiation in a wavelength range of 200 to 400 nm, depending on the UV photoinitiator used, in particular using high-pressure or medium-pressure mercury lamps at a power of 80 to 240 W / cm , The irradiation intensity is adapted to the respective quantum yield of the UV photoinitiator and the degree of crosslinking to be set.

Furthermore, it is possible in a design to crosslink the PSAs with electron beams. Typical irradiation devices that can be used are linear cathode systems, scanner systems or segmented cathode systems, if it is an electron beam accelerator. A detailed description of the state of the art and the most important process parameters can be found at Skelhome, Electron Beam Processing, in Chemistry and Technology of UV and EB formulation for Coatings, Inks and Paints, Vol. 1, 1991, SITA, London. The typical acceleration voltages are in the range between 50 kV and 500 kV, preferably 80 kV and 300 kV. The applied waste cans range between 5 to 150 kGy, in particular between 20 and 100 kGy. Both crosslinking methods or other methods enabling high-energy irradiation can also be used.

The invention further relates to the use of the inventive double-sided pressure-sensitive adhesive tapes for bonding or producing optical liquid-crystal data displays (LCDs), the use for bonding LCD glasses and liquid-crystal data displays which have an inventive pressure-sensitive adhesive tape in their product structure. For use as pressure-sensitive adhesive tape, the double-sided pressure-sensitive adhesive tapes may be covered with one or two release films or release papers. In a preferred embodiment, siliconized or fluorinated films or papers, e.g. Glassine, HPDE or LDPE coated papers are used, which in turn are provided with a release layer based on silicones or fluorinated polymers.

Examples

The invention will be described below without wishing to be unnecessarily limited by the choice of examples.

The following test methods were used.

Test Methods

A.Xiansmjssjoη

The transmission was measured in the wavelength range from 190 to 900 nm using a Uvikon 923 from the company Biotek Kontron. The Absolute Transmission is given as the value at 550 nm in%.

B. PjnhoJes

A commercially very strong light source (for example overhead projector type Liesegangtrainer 400 KC type 649, halogen lamp 36 V, 400 W) is completely light-tight covered with a mask. This mask contains in the middle a circular opening with a diameter of 5 cm. The double-sided LCD tape is placed on this circular opening. In fully darkened surroundings, the number of pinholes is then counted electronically or visually. These are recognizable as translucent dots when the light source is switched on.

The reflection test is carried out according to DIN standard 5063 part 3. The measuring instrument used was an Ulbrecht sphere type LMT. The reflectance is given as the sum of directed and scattered light fractions in%.

Ppjymer.1

A conventional for radical polymerizations 200 L reactor was 2400 g

Acrylic acid, 64 kg of 2-ethylhexyl acrylate, 6.4 kg of N-isopropylacrylamide and 53.3 kg of acetone / isopropanol (95: 5). 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 ⁰ C and the reaction was carried out constantly at this external temperature. After 1 h reaction time again 40 g of AIBN was added. After 5 h and 10 h each was diluted with 15 kg acetone / isopropanol (95: 5). After 6 and 8 h 100 g Dicycloheixylperoxydicarbonat (Perkadox ^® 16, Fa. Akzo Nobel) were each dissolved in 800 g of acetone was added respectively. The reaction was stopped after 24 h reaction time and cooled to room temperature. Networking

The PSAs are made from solution on a siliconized release paper

(PE.gecoatetes release paper from Loparex) coated, for 10 minutes in

Drying oven dried at 100 ° C and then crosslinked with 25 kGy dose at an accelerating voltage of 200 kV. The mass application was in each case 50 g / m ²

F.Qjie. (A | _: _Bedamßfunιg):

A polyethylene terephthalate copolymer was mixed with 20% by weight of titanium dioxide (average diameter 0.25 μm) in a kneader for 2 hours at 180 ° C and dried under vacuum. Subsequently, in a single-screw extruder, the film material was extruded through a slot die (T-shape, 300 μm slot gap) at 280 ^° C. The film is applied to a mirrored chill roll. It is then stretched by tempering at 90 to 95 ° C 3.5 times in the longitudinal direction. Then the film moved into a jig. There is stretched by means of brackets at temperatures between 100 ⁰ C and 110 ⁰ C 4 times in the transverse direction. The mixture is then postcured again for 10 s at 210.degree. Before winding, a 13 g / m ² paper fleece is injected to prevent blocking. In this state, the film could be wound and stored. The white PET film has a total thickness of 38 μm.

After unwinding and removing the nonwoven, this PET film is coated on one side with aluminum until a full-surface aluminum layer is applied to one side. The film was vapor-deposited at a width of 300 mm by the sputtering method. Here, positively charged, ionized argon gas is fed into a high-vacuum chamber. The charged ions then strike a negatively charged Al plate and dissolve aluminum particles at the molecular level, which then deposit on the polyester film that passes over the plate.

R6.f6.renzfpJje.XAJ _: vapor deposition): A 38 μm PET film extruded with white pigments as filler, the company Toray (Lumirror ™ 38E20) was coated on one side with aluminum until a full-surface aluminum layer is applied on one side , The film was vapor-deposited at a width of 300 mm by the sputtering method. Here, positively charged, ionized argon gas is fed into a high-vacuum chamber. The charged ions then hit a negatively charged Al plate and dissolve aluminum particles at the molecular level, which then deposit on the polyester film passed over the plate.

He.reteN.ung.der.sclMaCzen.Fa.Cbei The black color was made from 4 parts Hardener CVL no. 10 (from Dainippon Ink and Chemicals, Inc.) and 35 parts Daireducer ™ V No. 20 (from Dainippon Ink and Chemicals, Inc.) and 100 parts Panacea ™ CVL-SPR805 paint (from Dainippon Ink and Chemicals, Inc., a vinyl chloride / vinyl acetate based paint).

The disclosure of US 2004/0028895 for the preparation of the "Black Ink A" and the properties cited hereto are explicitly included in the disclosure of this application.

Herstejlu.πg.der wejßen .color:

The white paint was made from 2 parts Hardener CVL no. 10 (from Dainippon Ink and Chemicals, Inc.) and 35 parts Daireducer ™ V No. 20 (by Dainippon Ink and

Chemicals, Inc.) as well as 100 parts of color Panacea ™ CVL-SP709 (ex. Dainippon Ink and

Chemicals, Inc., a vinyl chloride / vinyl acetate based paint).

The disclosure of US 2004/0028895 for the preparation of the "White Ink W" and the properties cited hereto are explicitly included in the disclosure of this application.

. FQjie.l (sc.hwar ^ White):

On the Al-vapor-deposited side of the film (based on film AI coating), the black ink is applied over a flat area and dried at 45 ° C. for 48 hours. The black lacquer-coated side is completely and evenly black. The application is about 2 g / m ² .

FQjie.2 .. (^ sc.hwar white):

On the Al-vapor-deposited side of the film (based on film AI vapor deposition), the white paint is applied flat and dried for 48 hours at 45 ° C. The application is 2 g / m ² . Then it is painted again on the same side with the black color. It is dried again at 45 ° C for 48 hours. The double coated side is perfectly and evenly black. The application of both colors is 4 g / m ² . ReferenzfpJje.lXsch ^ ^ yvai wei.ß) .:

On the Al-vapor-deposited side of the film (based on reference film AI vapor deposition), the black ink is applied over a flat area and dried at 45 ° C. for 48 hours. The black lacquer-coated side is completely and evenly black. The application is about 2 g / m ² .

ReferenzfpJje.2.Xsch ^ ^ was wei.ß) j

On the Al-vapor-deposited side of the film (based on reference film AI vapor deposition), the white paint is applied over a flat area and dried at 45 ° C. for 48 hours. The application is 2 g / m ² . Then it is painted again on the same side with the black color. It is dried again at 45 ° C for 48 hours. The double coated side is perfectly and evenly black. The application of both colors is 4 g / m ² .

Example 1.

The film 1 is coated in the lamination process with the polymer 1 on both sides with 50 g / m ² .

Beispjel_2 The film 2 is coated in the lamination process with the polymer 1 on both sides with 50 g / m ² .

Referen.zbeisp.ie.l..1.

The reference film 1 is coated in the lamination process with the polymer 1 on both sides with 50 g / m ² .

Reference Example 2

The reference film 2 is coated in the lamination process with the polymer 1 on both sides with 50 g / m ² .

Results

Examples 1 and 2 were tested together with Reference Examples 1 and 2 according to test methods A, B and C. The results are shown in Table 1.

From the results of Table 1 it can be seen that Examples 1 to 2 are clearly superior to Reference Examples 1 and 2 in terms of optical defects (pinhole freedom) and total reflection rate. This significantly increases the luminous efficacy in the LCD application.

According to the invention and surprisingly, the pressure-sensitive adhesive tapes according to the invention show no blocking behavior at any stage of their production. This also applies to the wine- or bilaterally metallized film, and even after painting. Such an advantageous behavior could not expect the expert.

It was surprising for the person skilled in the art that the bright, in particular white color pigments or particles did not cause the problems that were known from anti-blocking agents, in particular no pinholes.

Claims

claims

1. pressure-sensitive adhesive tape, in particular for the production or bonding of optical liquid crystal data displays (LCDs), with a top and a bottom, with light-reflecting properties on the

The upper side and light-absorbing properties on the underside, comprising a carrier film having a top and a bottom, wherein the pressure-sensitive adhesive tape is provided on both sides with a pressure-sensitive adhesive layer, characterized in that the carrier film has a content of anti-blocking agents of less than 4000 ppm, the carrier film lightly colored and at least one light-absorbing ink-carrying layer is provided at least between the underside of the carrier film and the pressure-sensitive adhesive layer located on this side.

2. Pressure-sensitive adhesive tape according to at least one of the preceding claims, characterized in that the light coloration of the carrier layer is achieved by the presence of white pigments.

3. Pressure-sensitive adhesive tape according to claim 1, characterized in that the carrier film has a content of anti-blocking agents of less than 1000 ppm, preferably less than 500 ppm, particularly preferably of 0 ppm.

4. Pressure-sensitive adhesive tape according to at least one of the preceding claims, characterized in that at least one of the sides of the carrier film has a roughness of less than 400 nm, in particular of less than 300 nm, and preferably of more than 50 nm.

5. Pressure-sensitive adhesive tape according to at least one of the preceding claims, characterized in that the carrier film has a thickness of between 250 μm and 4 μm, preferably between 50 μm and 8 μm, very preferably between 36 μm and 12 μm.

6. Pressure-sensitive adhesive tape according to at least one of the preceding claims, characterized in that the carrier film is provided on its underside with a metallically reflecting coating.

7. A method for producing a pressure-sensitive adhesive tape according to at least one of the preceding claims, characterized in that the surface was roughened on at least one of the sides of the carrier film prior to the preparation of the pressure-sensitive adhesive tape, in particular roughened such that it has a roughness of less than 400 nm, preferably smaller 300 nm, and preferably more than

50 nm.

8. The method according to claim 7, characterized in that the roughness is achieved by pressing a fleece and / or fabric and / or by treatment with surface-structured rollers and optionally refined by polishing.

9. The method according to claim 8, characterized in that the carrier film is pretreated before or after the roughening by etching, by treatment with corona or plasma and / or by equipping with a primer.

10. The method according to claim 7 for the preparation of a pressure-sensitive adhesive tape according to claim 6, characterized in that the metallically reflective coating is achieved by sputtering (cathode sputtering coating).

11. Use of a pressure-sensitive adhesive tape according to any one of claims 1 to 7 or obtainable by a process of claims 8 to 11 for the production or bonding of manufacturing or bonding of liquid crystal optical data displays (LCDs).

12. Use according to claim 11 for bonding an LCD glass.

13. Liquid crystal data display (LCD) comprising a pressure-sensitive adhesive tape according to at least one of claims 1 to 6.