EP1913108A1

EP1913108A1 - Double-sided pressure-sensitive adhesive tapes for producing lc displays having light-reflecting and absorbing properties

Info

Publication number: EP1913108A1
Application number: EP05850430A
Authority: EP
Inventors: Marc Husemann; Reinhard Storbeck
Original assignee: Tesa SE
Current assignee: Tesa SE
Priority date: 2005-07-21
Filing date: 2005-12-02
Publication date: 2008-04-23
Also published as: DE112005003598A5; CN101223256A; TW200705011A; US20100104774A1; JP2009501814A; WO2007009502A1; KR20080047505A

Abstract

Pressure-sensitive adhesive (PSA) tape, intended in particular for producing or bonding optical liquid-crystal data displays (LCDs), having a carrier sheet and two PSA layers, the carrier sheet having translucent properties and there being a metallic layer and a white-coloured layer between the carrier sheet and at least one of the PSA layers.

Description

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 PSA tapes with multilayer carrier structures and with light-reflecting and absorbing properties for the production of liquid crystal 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 low outgassing behavior, the pressure-sensitive adhesive tapes should be usable over a wide temperature range and fulfill certain optical properties.

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

For the production of LC displays LEDs are glued as a light source with 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 consists in the coloring of the carrier material. In the electronics industry are very preferred Double-sided pressure-sensitive adhesive tapes with polyester film carriers (PET) are used because they can be punched very well. The PET supports can be dyed, for example, with carbon black or black color pigments in order 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 particles or other black pigment particles can be introduced, with the result that complete absorption of the light is not 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.

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 than 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. In this case, there is always a weak spot in the double-sided 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 concept also has several disadvantages. On the one hand, there are also slight imperfections (pinholes) caused by anti-blocking agents during the film extrusion process be registered. These are not acceptable for use in the LC display. Furthermore, the maximum absorption properties do not meet the requirements, since only relatively thin paint layers can be applied. Also, one is limited in the layer thicknesses upwards, otherwise the mechanical properties of the support material would change.

There is a trend in the development of LC displays. On the one hand, the LC displays are to become lighter and flatter, and there is a strong 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 risk increases that more and more light penetrates outward into the edge zone of the LCD panel ("blind area" 1) With this development, the requirements for the shading properties (black out properties) of the double-sided adhesive tape are therefore also increasing, and there is a need for new concepts for the production of black adhesive tapes.

On the other side of the double-sided pressure-sensitive adhesive tape, this 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 on the other side.

However, this concept also has disadvantages, since - when the viewing angle in the LC display is about 45 ° - light diffusion is perceived, which arise due to the strong reflection of the light. To avoid this - but still increase the light output - a gray reflective layer is needed.

Fig. 1 shows the concept of a double-sided adhesive tape with a gray layer for

Absorption and a layer for reflection according to the prior art; mean

1 LCD glass 4 light source (LED)

2 double-sided gray-white 5 beams of adhesive tape 6 double-sided adhesive tape

3 pressure-sensitive adhesive 7 light guide 8 reflective foil 11 white reflective side

9 LCD housing 12 visible area

10 gray absorbing 13 "blind" area tape side

Some concepts for producing gray adhesive tapes are also known in the literature.

For example, e.g. the simplest method to mix gray particles of the adhesive or gray to paint a support side. However, these methods are relatively expensive, since it is relatively difficult to make the right color shade over the appropriate color particle composition.

The object of the invention is therefore to provide a double-sided pressure-sensitive adhesive tape which dispenses with the abovementioned processes and is able to completely absorb light, thereby enabling a reflection of light by means of a gray color side.

In the context of this invention, it has surprisingly been found that this can be achieved in an outstanding manner by the degree of filling of the carrier film with white color particles in combination with a metallized and white lacquered back.

The main claim accordingly relates to a pressure-sensitive adhesive tape, in particular for the production or bonding of optical liquid crystal data displays (LCDs), comprising a carrier film and two pressure-sensitive adhesive layers, the carrier film having translucent properties and between the carrier film and at least one of the pressure-sensitive adhesive layers a metallic layer and a white colored Layer are provided.

Translucency or translucent properties are the translucent properties (compared to transparency, which describes transparency). Translucent bodies appear cloudy but may appear clear when in contact with a substrate (clarity of contact). For the purposes of this invention, the carrier films are designated in particular as translucent if they have a transmission, measured by measuring method A, in the range between a minimum of 5% and a maximum of 95%, in particular between 50 and 70%.

The subclaims relate to advantageous and / or particularly suitable embodiments of the invention. By way of example, double-sided pressure-sensitive adhesive tapes may be mentioned, which consist of a single-layer or multi-layered carrier material and two identical or different pressure-sensitive adhesive compositions.

In a particularly advantageous embodiment according to FIG. 2, the pressure-sensitive adhesive tape according to the invention consists of a translucent carrier film layer (a) filled with white color pigments, wherein the degree of translucency can be variably adjusted by the degree of filling of white pigments, a white lacquer layer (c), a metallic layer ( d) and two pressure-sensitive adhesive layers (b) and (b ¹ ), wherein the pressure-sensitive adhesives may be identical or differ from one another.

In a further preferred embodiment of the invention, the pressure-sensitive adhesive tape according to the invention has the product structure shown in FIG. 3, in which the pressure-sensitive adhesive tape consists of a translucent carrier film layer filled with white color pigments, a white primer layer (s), a metallic one, as is variably adjustable in the translucency above Layer (d) and two pressure-sensitive adhesive layers (b) and (b '), wherein the PSAs may in turn be identical or different from each other.

The invention will be explained in more detail below:

The carrier film (a) is preferably between 5 and 250 μm, more preferably between 8 and

50 μm, most preferably between 12 and 36 μm thick. The degree of filling of white

Pigments can be chosen variably, so that different degrees of

Translucency result and the carrier film appears by the different degrees of whitening in different shades of gray.

The layer (e) is a white primer layer. The layer thickness is advantageously between 1 and 15 .mu.m: preferably between 3 and 10 .mu.m.

The pressure-sensitive adhesive layers (b) and (b ') preferably have a thickness of 5 μm each up to 250 μm, independently of each other. The layers can also be made equally thick.

The layer thickness of the layer (d) is preferably between 0.01 μm and 5 μm. In a particularly preferred procedure, the production of the metallic layer

Aluminum or silver evaporated on the carrier film (a).

The lacquer layers (c) are light-reflecting and at the same time light-absorbing and white.

The layer thickness of the layer (c) is preferably between 1 .mu.m and 15 .mu.m. In the sense of the

Layer (c) can also be provided a plurality of superposed paint layers.

The individual layers (b), (b ¹ ), (c), (d) and (e) within the double-sided pressure-sensitive adhesive tape may be designed differently with regard to the layer thickness, but advantageously some or all of these layers may be equally thick. Thus, for example different thicknesses or equal thick pressure-sensitive adhesive layers (b) and applied (b ^1).

Carrier film (a)

In principle, all filmic polymer supports which can be dyed white (during and / or after their production) and have a light translucency can be used as film supports. Thus, for example, Polyethylene, polypropylene, polyimide, polyester, polyamide, polymethacrylate, etc. use. In a particularly preferred procedure polyester films are used, most 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.

Furthermore, up to 12 .mu.m thick, in particular exactly 12 .mu.m thick PET films are very preferred because they leave 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. In addition, when the PET is stained, the translucency moves within a balanced framework, which is very advantageous for the function used for the invention.

To improve the anchoring, it is very advantageous to pretreat the films. The films may be etched (eg with trichloroacetic acid or trifluoroacetic acid), pretreated with corona or plasma or equipped with a primer (eg saran). Furthermore, the film contains white color pigments or white color-bearing particles. It The pigments or particles familiar to the person skilled in the art are suitable. Examples are, for example, all customary titanium dioxide particles or barium sulfate particles for whitening. However, the pigments or particles should always be smaller in diameter than the final layer thickness of the carrier film. The degree of whitening is controlled by the film thickness and the transmission. The light transmission of the white film should preferably be at most 95% and at least 50% in order to achieve a subsequent gray coloration of the page.

The optimum degree of filling with white color particles depends on the chemical composition and the total layer thickness of the film. Optimal colorations can be achieved with 2 to 20 wt .-% of particles based on the film material.

Primer layer (s)

The primer layer (e) performs various functions. A function is the additional absorption of the outside light. Therefore, in an advantageous embodiment of the invention which makes use of this function in particular, for the double-sided pressure-sensitive adhesive tape the transmission should be in a wavelength range of 300-800 nm at <0.5%, more preferably at <0.1%, very preferably at <0.01% lie. In another function, the primer layer (e) fulfills the light reflection. The light reflection should preferably be greater than 65% according to test method c. In a further function, the primer layer (e) improves the anchoring of the pressure-sensitive adhesive composition (b) or (b ¹ ) on the carrier film (a).

In a very preferred embodiment, a white primer layer is used according to the invention.

Primers can be coated as 100% systems, solution or dispersion. As a rule, primers consist of an adhesion-promoting matrix, which is particularly preferably blended with a reactive component. In the context of this invention, white color pigments or white color-bearing substances are added to the primer. The adhesion-promoting matrix used can be, for example, polyesters, polyurethanes, polyacrylates, silicones and polymethacrylates. As the reactive component, it is possible to use, for example, difunctional or polyfunctional isocyanates, difunctional or polyfunctional aziridines, difunctional or polyfunctional hydrazines, di- or polyfunctional oxazolidines and polyfunctional aromatic dicarboxylic acid anhydrides. The reactive components are chosen so that a reaction with the pressure-sensitive adhesive (b) and (b ¹ ) can take place. Examples of multifunctional aziridines are Crosslinker CX-100 ™ from ICI, XAMA ™ 7, XAMA ™ 2, and XAMA ™ 22Q from Ichemco, and for multifunctional isocyanates the Desmodur series of the company Lanxess and Curing Agent W, W3, WS5, D, 100D, RF-AE of the company Ichemco. Bi- or multifunctional oxazolidines are commercially available and trade name EPOROS from Nippon Shokubai; also hydrazines and aromatic dicarboxylic acid anhydrides.

For dilution of the difunctional or multifunctional reactive components it is preferred to use e.g. aqueous polyacrylate dispersion, such as. Neocryl A-45 ™ from Zeneca, or SK 1800 from Nippon Shokubai.

The dispersion incorporates the reactive primer and thus facilitates the handling of the coating of the substrate as a smear or with the aid of the transfer technique. In particular for primer dispersions it may be advantageous to use further additives, e.g. for improving the coatability by reducing the foaming or additives for improving the stability or the durability of dispersions. Here, the additives known to the person skilled in the art can be used.

For dilution of the bifunctional or multifunctional reactive components, solvent-based adhesion-promoting matrices are used in a further advantageous variant. Commercial examples of this are e.g. Primer Unisol 11 of the company Ichemco, or NX 350 and NX 380 of the company Nippon Shokubai.

In a very preferred embodiment of the invention, the adhesion-promoting component and / or the reactive component titanium dioxide or barium sulfate are admixed as color-carrying particles. Due to this additivation, in addition to the function of complete light absorption, a light reflection is additionally effected at a very high additive content (in particular> 20% by weight). For optimum coloration of the primer layer (s), the particle size distribution of the white color pigments is of great importance. Thus, the particles should be at least smaller than the total layer thickness of the primer layer (e). Preference is given to using particles having an average diameter of 50 nm to 5 μm, more preferably between 100 nm and 3 μm, most preferably between 200 nm and 1 μm. Such size qualities can be achieved, for example, by targeted grinding in ball mills with subsequent targeted sieving. Furthermore, a homogeneous distribution of the color particles in the primer matrix is very advantageous for the quality of the coloring. For this purpose, an intensive mixing process is preferably used which mixes in an optimal procedure by means of an Ultraturrax (high performance homogenizer). With this step, the color particles can then be disrupted again and homogenized in the primer matrix.

Lacquer layer (c)

The lacquer layer (c) fulfills various functions. A function of the color layer is the additional absorption of the outside light. Therefore, in an advantageous embodiment of the invention which makes use of this function in particular, for the double-sided pressure-sensitive adhesive tape, transmission in a wavelength range of 300 to 800 nm at <0.5%, more preferably <0.1%, should be extremely preferred are <0.01%.

Furthermore, the lacquer layer (c) fulfills the function of light reflection. The light reflection should preferably be greater than 65% according to test method c. Very preferably, this is achieved with a white lacquer layer.

Paints can be coated as 100% systems, solution or dispersion. Paints consist of a hardening binder matrix (preferably thermosetting system, but also radiation-curing system) and white color pigments and are then applied with a printing unit (eg in flexographic printing). In order to achieve a sufficient opacity, the application can also take place in several steps, so that several layers of ink are applied. Furthermore, the ink can also be applied with an anilox roller applicator. With this, higher layer thicknesses of color can be applied in one step. The paints may be based on, for example, polyesters, polyurethanes, polyacrylates and / or polymethacrylates. Furthermore, further known coating additives may be added. The paint preferably further contains a crosslinking component, which serves in particular for curing. It can be activated either by radiation curing (electron beam curing, eg by means of di- or multifunctional vinylic compounds, UV curing, for example either by means of UV photocation generators, in particular in combination with di- or multifunctional epoxides, or by means of UV radical generators of the Norrish type -I or Norrish-II, in particular in conjunction with dioder multifunctional vinylic compounds, such as acrylates or methacrylates) or by thermally activatable compounds, such as di- or multifunctional isocyanates, di- or multifunctional epoxides, and / or di- or multifunctional hydroxides , depending on the dependence of the base matrix of the paint. In a highly preferred inventive procedure are considered color-bearing Particles of titanium dioxide or barium sulfate to the paint, which forms the paint layer mixed. Due to this additivation, in addition to the function of complete light absorption, a light reflection is additionally effected at a very high additive content (in particular> 20% by weight). For optimal coloration of the lacquer layer (c), the particle size distribution of the white color pigments is of great importance. Thus, the particles should be at least smaller than the total layer thickness of the lacquer layer (c). Preference is given to using particles having an average diameter of 50 nm to 5 μm, more preferably between 100 nm and 3 μm, most preferably between 200 nm and 1 μm. For obtaining such size qualities, see above.

Metallic layer (d)

For the production of a particularly highly reflective and light-absorbing side, a silver-colored lacquer can be applied to the film layer (a) and / or the film layer (a) can be coated on one or both sides with a metal, e.g. Aluminum or silver, to be vaporized. For the variant with silver-colored lacquer, a binder matrix is mixed with silver color pigments. As the binder matrix, e.g. Polyurethanes or polyesters which have a high refractive index and a high transparency. However, the color pigments can also be incorporated in a polyacrylate or polymethacrylate matrix and then cured as a lacquer.

In a preferred embodiment, the film layer (a) is vapor-deposited on both sides with aluminum or silver. In order to achieve particularly excellent reflective properties, the sputtering process should be controlled so that the aluminum or silver is applied very evenly to achieve optimum reflection (avoidance of scattering effects). Furthermore, in a very preferred embodiment, the PET film is pretreated with plasma or corona before being steamed with aluminum or silver. Through the use of the reflective layer (b), on the one hand the light is deliberately reflected, and on the other hand the transmission of the light through the carrier material is reduced or avoided. In addition, surface roughnesses of the carrier film are compensated.

Pressure Sensitive Adhesives (b) and (b ')

The pressure-sensitive adhesives (b) and (b ¹ ) are identical in a preferred embodiment on both sides of the pressure-sensitive adhesive tape. However, in a specific embodiment it may also be advantageous if the pressure-sensitive adhesives (b) and (b ¹ ) differ from one another, in particular by their layer thickness and / or their chemical properties 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, preference is given to using acrylate, natural rubber, synthetic rubber, silicone or EVA adhesive. The PSA preferably has a high transparency or is optionally colored white. Furthermore, it is possible to process the further pressure-sensitive adhesives known to the person skilled in the art, as listed, for example, in the "Handbook of Pressure Sensitive Adhesive Technology" by Donatas Satas (van Nostrand, New York 1989).

For natural rubber adhesives, the natural rubber is preferably ground to a molecular weight (weight average) not less than about 100,000 daltons, preferably not less than 500,000 daltons, and 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 from all available qualities such as Crepe, RSS, ADS, TSR or CV types, depending on the required purity and viscosity level, and the synthesis of 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. Further, it is preferable to add to the rubbers, for the purpose of improving the processability, thermoplastic elastomers having a weight proportion of 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

(Meth) acrylate PSAs used.

(Meth) acrylate PSAs used according to the invention, which are obtainable by free-radical polymerization, are preferably based to at least 50% by weight on at least one acrylic monomer from the group of compounds of the following general formula:

In this case, the radical R ₁ = H or CH ₃ ; and the radical R ₂ is H or CH ₃ or is selected from the group comprising the branched and unbranched, saturated alkyl groups having 1-30 carbon atoms.

The monomers are preferably chosen such that the resulting polymers can be used as pressure-sensitive adhesives at room temperature or higher temperatures, in particular such that the resulting polymers have pressure-sensitive adhesive properties according to the Handbook of Pressure Sensitive Adhesive Technology by Donatas Satas (van Nostrand, New York 1989).

In a further inventive embodiment, 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 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 1-20 C atoms or H.

The molecular weights M _w (weight average) 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 methacrylate, 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 methacrylate, isobornyl acrylate, isobornyl methacrylate and 3,5-dimethyl adamantyl acrylate.

In an advantageous procedure, monomers are used which contain polar groups such as carboxyl radicals, sulfonic and phosphonic acids, hydroxy radicals, lactam and lactan, N-substituted amide, N-substituted amine, carbamate, epoxy, thiol, alkoxy, cyano radicals, ethers or something similar.

Moderate basic monomers are N, N-dialkyl-substituted amides, such as N ₁ N-dimethylacrylamide, NN-Dimethylmethylmethacrylamid, N-tert-butylacrylamide, N-vinylpyrrolidone, N-vinyllactam, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, diethylaminoethyl acrylate, NMethylol - methacrylamide, N- (buthoxymethyl) methacrylamide, N-methylolacrylamide, N (ethoxymethyl) acrylamide, N-isopropylacrylamide, although 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-acryloyloxypropionic acid, trichloroacrylic acid, fumaric acid, crotonic acid, aconitic acid, dimethylacrylic acid, although 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, in an advantageous procedure photoinitiators with a copolymerizable double bond used. Suitable photoinitiators are Norrish I and Norrish II photoinitiators. Examples include benzoin and an acrylated benzophenone from. UCB (Ebecryl ^® P 36) In principle, all photoinitiators known to those skilled be copolymerized which can crosslink via a free-radical under UV irradiation the polymer. An overview of possible usable photoinitiators which can be functionalized with a double bond is given in Fouassier: "Photoinitiation, Photopolymerization and Photocuring: Fundamentals and Applications", Hanser Verlag, Munich 1995. In addition, Carroy et al., In "Chemistry and Technology of UV and EB Formulation for Coatings, Inks and Paints ", Oldring (ed.), 1994, SITA, London.

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, the aromatic nuclei preferably consisting of C ₄ to cis building blocks and also containing 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 the aforementioned monomers, this list is not meant to be exhaustive.

By increasing the aromatic content, the refractive index of the PSA increases, and the scattering between the LCD glass and the PSA, e.g. by extraneous light is minimized.

For further development, the PSAs may be mixed with resins. Suitable tackifying resins to be added are the previously known adhesive resins described in the literature. 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 with the appropriate Polyacrγlat 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. The presentation of the state of knowledge in the "Handbook of Pressure Sensitive Adhesive Technology" by Donatas Satas (van Nostrand, 1989) is expressly pointed out.

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.

Further, optional plasticizers (plasticizers), other fillers (such as fibers, carbon black, zinc oxide, chalk, solid or hollow glass spheres, microspheres of other materials, silicic acid, silicates), nucleating agents, electrically conductive materials, e.g. conjugated polymers, doped conjugated polymers, metal pigments, metal particles, metal salts, graphite, blowing agents, compounding agents and / or anti-aging agents, e.g. be added in the form of primary and secondary antioxidants or in the form of sunscreens.

In a further advantageous embodiment of the invention, the pressure-sensitive adhesive (b ¹ ) contains light-reflecting particles, such as, for example, white color pigments (titanium dioxide or barium sulfate) as a filler.

In addition, 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. B. 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 Norrish-I or Norrish-II type may contain the following radicals: benzophenone, acetophenone, benzil, benzoin, hydroxyalkylphenone, phenylcyclohexylketone, anthraquinone, trimethylbenzoylphosphine oxide, methylthiophenylmorpholine ketone, Aminoketone, azobenzoin, thioxanthone, hexarylbisimidazole, triazine or fluorenone, where each of these radicals may additionally be substituted by one or more halogen atoms and / or one or more alkoxy groups and / or one or more amino groups or hydroxy groups. A representative overview is given by Fouassier: "Photoinitiation, Photopolymerization and Photocuring: Fundamentals and Applications", Hanser-Verlag, Munich 1995. In addition, Carroy et al. in "Chemistry and Technology of UV and EB Formulation for Coatings, Inks and Paints", Oldring (ed.), 1994, SITA, London.

Production process for the acrylic PSAs

For the polymerization, the monomers are advantageously chosen such that the resulting polymers can be used as PSAs at room temperature or higher temperatures, in particular in such a way that the resulting polymers have pressure-sensitive adhesive properties in accordance with Donatas Satas' Handbook of Pressure Sensitive Adhesive Technology (van Nostrand, vol. New York 1989).

To achieve a for PSAs preferred glass transition temperature T _G of the polymers of T _G <25 ⁰ C in accordance with the above, the monomers predicted very preferably selected, and the quantitative composition of the monomer mixture advantageously chosen such that analogue according to an equation (G1) to the Fox Equation (G1) (see TG Fox, Bull. Am. Phys Soc., 1 (1956) 123) gives the desired T _G value for the polymer.

τ "4 τ," (Gl) n 'G, n 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, Methoden der Organischen Chemie, 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 are potassium peroxodisulfate, dibenzoyl peroxide, cumene hydroperoxide, cyclohexanone peroxide, di-t-butyl peroxide, Azodiisosäurebutyronitril, Cyclohexylsulfonylacetylperoxid, 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 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; In particular, pressure-sensitive adhesives having average molecular weights M _w of 400,000 to 1,400,000 g / mol are produced. 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 selected, 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, for example, be shrink-wrapped in films (in the simplest case, ice cubes) and then polymerized in water to high conversion. 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 production method for the poly (meth) acrylate pressure-sensitive adhesive compositions is anionic polymerization. Here inert inert solvents are preferably used as the reaction medium, such as 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 prepared is controlled by the ratio of initiator concentration to monomer concentration. Suitable polymerization initiators are, for example, n-propyllithium, n-butyllithium, sec-butyllithium, 2-naphthyllithium, cyclohexyl lithium or octyllithium, although this list is not exhaustive. Furthermore, initiators based on samarium complexes for the polymerization of acrylates are 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 chosen such that acrylate monomers, e.g. n-butyl acrylate and 2-ethylhexyl acrylate, can be polymerized directly 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:

wherein R and R ^{1 are} independently selected or the same and

- 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 d- to Ci ₈ alkyl radicals; C ₃ to C ₈ alkenyl radicals; C ₃ to Cis 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 * may be any (in particular organic) radical,

with at least one ester group, amine group, carbonate group, cyano group, isocyano group and / or epoxy group and / or sulfur-substituted C _r Cis-alkyl radicals, C ₃ -C ₈ -alkenyl radicals, C ₃ -C ₈ -alkynyl radicals; C ₃ -C ₂ -cycloalkyl radicals

- C ₆ -C ₈ - aryl or benzyl radicals

- Represent hydrogen.

Control reagents of type (I) preferably consist of the following 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 ^{2 can} also be selected independently of R and R ¹ from the above-mentioned group for these radicals.

In the conventional 'RAFT process', polymerisation is usually carried out only to low conversions (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 unsaturated or aromatic, saturated, iii) ester -COOR ^11, alkoxides -OR ¹² and / or phosphonates -PO (OR ¹³ J _2, wherein R ^11, R ¹² or R ¹³ radicals from the group ii ) stand.

Compounds of (Va) or (Vb) may also be bound 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 chosen for the polymerization of compounds of the type:

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

2,2,6,6-tetramethyl-piperidine-1-oxyl (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-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 WO 98/44008 A1 discloses specific nitroxyls based on morpholines, piperazinones and piperazine diones DE 199 49 352 A1 describes heterocyclic compounds al koxyamine as regulators in controlled radical polymerizations. Corresponding developments of the alkoxyamines and the corresponding free nitroxides improve the efficiency for the production of polyacrylates (Hawker, contribution to the Annual General Meeting of the American Chemical Society, spring 1997, Husemann, contribution to the IUPAC World-Polymer Meeting 1998, Gold Coast).

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 various possibilities of ATRP are further described in the documents US 5,945,491 A, US 5,854,364 A and US 5,789,487 A.

Coating process, equipment of the carrier material

For the production, the PSA is coated from solution onto the carrier material in a preferred procedure. To increase the anchoring of the pressure-sensitive adhesive, layers (a) and / or (b) can optionally be pretreated. 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. 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 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%.

Furthermore, the twin-screw extruder can also be used for compounding with the carbon black. In this way, the carbon black can be distributed very finely distributed in the pressure-sensitive adhesive matrix.

The hotmelt is very preferably 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 methods are described in Donatas Handbook of Pressure Sensitive Adhesive Technology Satas (van Nostrand, New York 1989) described. In a further embodiment is coated via a melt nozzle. In another preferred method is coated by extrusion. The extrusion coating is preferably carried out with an extrusion die. The extrusion dies used can advantageously come from one of the following three categories: T die, fishtail die and ironing nozzle. The individual types differ in the shape of their flow channel. The coating can also give the PSAs orientation.

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, the PSAs are crosslinked in an advantageous embodiment of the invention with electron beams. Typical irradiation devices which are advantageously used are linear cathode systems, scanner systems or segment cathode systems, if they are electron beam accelerators. A detailed description of the state of the art and the most important process parameters can be found in 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 and 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 manufacturing of liquid crystal optical data displays (LCDs), the use of LCD glasses and liquid crystal data displays and devices with liquid crystal data displays, which have inventive pressure-sensitive adhesive tape in their product structure. For use as a pressure-sensitive adhesive tape, the double-sided pressure-sensitive adhesive tapes may be covered with one or two release films and / or release papers. Preference is given to using siliconized or fluorinated films or papers, for example glassine, HPDE or LDPE-coated papers, which in turn are provided with a release layer based on silicones or fluorinated polymers. In a particularly preferred embodiment, siliconized PET films are used as the cover. Particularly advantageous are the pressure-sensitive adhesive tapes according to the invention for bonding light-emitting diodes (LED) as a light source with the LCD module.

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 ... TransmjssiQ n

The transmission was measured in the wavelength range from 190 to 900 nm using a Uvikon 923 from the company Biotek Kontron. The measurement is carried out at 23 ⁰ C. Absolute transmission is reported as the value at 550 nm in%, based on the total light absorption (transmission 0% = no light transmission, transmission 100% = complete light transmission).

B. Pjnholes

A commercially very strong light source (eg 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 environment then the number of Pinholes electronically or visually counted. These are recognizable as translucent dots when the light source is switched on.

on | C ... Reflect

The reflection test is carried out according to DIN standard 5036 part 3, DIN 5033 part 3 and DIN 5033 part 4. The measuring instrument was an Ulbricht sphere type. LMT (50 cm diameter) used in conjunction with a digital indicator TYP LMT Tau-p meter. The integral measurements are made with a light source according to standard light A and V (A) - matched Si photoelement. It was measured against a glass reference sample. The reflectance is given as the sum of directed and scattered light fractions in%.

Polymer 1

A 200 L reactor conventional for radical polymerizations was charged with 2400 g of acrylic acid, 64 kg of 2-ethylhexyl acrylate, 6.4 kg of N-isopropylacrylamide and 53.3 kg of acetone / isopropanol (95: 5). After 45 minutes, passing nitrogen gas while stirring, the reactor was heated to 58 ⁰ C and added 40 g of 2,2 ¹ -Azoisobuttersäurenitril (AIBN). Subsequently, the outer heating bath was heated to 75 ° C and the reaction was carried out constantly at this external temperature. After 1 h reaction time again 40 g of AIBN was added. After 5 h and 10 h each was diluted with 15 kg acetone / isopropanol (95: 5). After 6 and 8 h 100 g of dicyclohexyl peroxydicarbonate (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. The solution is mixed with 0.3 wt .-% aluminum chelate (3% solution in isopropanol) and immediately applied to a 50 microns siliconized PET liner surface. After drying at 120 ^° C. for 10 minutes, the application rate was 50 g / m ² .

Primer mass 1

In a barrel, 100 parts of primer Unisol 11 from the company Ichemco with 10 parts of a multifunctional isocyanate Curing Agent D (the company .Ichemco) and 25 parts

Titanium dioxide (<5 μm, 99.9+, mainly rutile structure) mixed thoroughly with a stirrer for 1 h. Subsequently, the mixture is further homogenized with an Ultraturrax (for about 30 minutes). The primer mass 1 is coated immediately thereafter. Lacquer i

In a Red Devil paint mixer, 42 parts of Acrydic A-910 (nitrogen-containing acrylic resin having a solids content of 50% from Dainippon Ink and Chemicals), 80 parts of Titanium White JR603 (Teikoku Kako Co. Ltd.), 6 parts of XyIoI, 6 parts of toluene, 6 parts of methyl ethyl ketone dispersed for 30 minutes. The mixture is then further homogenized in an Ultraturrax.

White film production:

Fojje.a) :.

A polyethylene terephthalate copolymer was mixed with 10% 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 to 90 to 95 ° C 3.5 times in the longitudinal direction. Then the film is driven into a tensioning device. There is stretched by means of brackets at temperatures between 100 ° C and 110 ° C 4-fold in the transverse direction. The mixture is then postcured again for 10 s at 210.degree. The white PET film has a total thickness of 36 μm. The transmission of the film according to test method A is 55%.

Fpjje.b):

A polyethylene terephthalate copolymer was mixed with 5% 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 to 90 to 95 ° C 3.5 times in the longitudinal direction. Then the film is driven into a tensioning device. There is stretched by means of brackets at temperatures between 100 ° C and 110 ° C 4-fold in the transverse direction. The mixture is then postcured again for 10 s at 210.degree. The white PET film has a total thickness of 36 μm. The transmission of the film according to test method A is 70%. FpJje_ (AJ _: Bedampfuπq) j.

The white PET films a) and b) are aluminum-coated on one side until a full-surface aluminum layer has been applied [the aluminum-aluminised films a * are formed from a) or b *) from b)]. 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 passed over the plate.

Foil (color painting):

BejspjeMj.

The film metallized on one side with aluminum a *) is coated flat on the AI side with the white primer composition 1 and dried at 120 ° C for 30 minutes. The side coated with the white primer is completely and uniformly white. The application is about 10 g / m ² . Subsequently, in the lamination process with the polymer 1 coated on both sides with 50 g / m ² .

BeispjeJ _. 2 _. : _.

The film metallized on one side with aluminum b *) is coated flat on the AI side with the white primer composition 1 and dried at 120 ° C. for 30 minutes. The side coated with the white primer is completely and uniformly white. The application is about 10 g / m ² . Subsequently, in the lamination process with the polymer 1 coated on both sides with 50 g / m ² .

: Beispjel.3..

The film metallized on one side with aluminum a *) is coated on the AI side with the white paint 1 area and dried at 120 ⁰ C for 30 minutes. The side coated with the white varnish is completely and evenly white. The application is about 10 g / m ² . Subsequently, in the lamination process with the polymer 1 coated on both sides with 50 g / m ² .

BeispjeJ _. 4 _. : _.

The film metallized on one side with aluminum b *) becomes on the AI side with the white one

Lacquer 1 coated flat and dried at 120 ° C for 30 minutes. The one with the white Paint coated side is completely and evenly white. The application is about 10 g / m ² . Subsequently, in the lamination process with the polymer 1 coated on both sides with 50 g / m ² .

Results

Examples 1 to 4 were tested according to test methods A, B and C. The test method A provides information about the total transmission of the double-sided adhesive tape and thus information about the degree of light absorption. The test method B determines whether the film contains optical defects. In contrast, the reflection (test C) must not exceed values of 65%, since otherwise the gray side would be too reflective and would appear too white. The results for the inventive examples are shown in Table 1.

From the results of Table 1, it can be seen that Examples 1 to 4 have excellent light-absorbing properties. Furthermore, Examples 1 to 4 show that the reflection and thus the gradation of the white / metallic shading can be controlled by the filler content. The white film with the lowest filler content and the thinnest layer thickness reflects the least and has the grayest color. By contrast, Examples 1 and 2 show that the film a *) with the highest white particle content has the lowest gray color.

Claims

claims

1. Pressure-sensitive adhesive tape, in particular for the production or bonding of optical liquid-crystal data displays (LCDs), comprising a carrier film and two pressure-sensitive adhesive layers, characterized in that the carrier film has translucent properties and between the carrier film and at least one of the pressure-sensitive adhesive layers a metallic layer and a white colored Layer are provided.

2. Pressure-sensitive adhesive tape according to claim 1, characterized in that the translucency of the carrier film is brought about by the presence of white pigments in the film, in particular by a weight fraction of from 2 to 20% by weight in the film material.

3. Pressure-sensitive adhesive tape according to at least one of the preceding claims, characterized in that the carrier film has a light transmittance of 50 to 95%.

4. Pressure-sensitive adhesive tape according to at least one of the preceding claims, characterized in that the white-colored layer is a primer layer.

5. Pressure-sensitive adhesive tape according to one of claims 1 to 3, characterized in that the white-colored layer is a lacquer layer.

6. Pressure-sensitive adhesive tape according to at least one of the preceding claims, characterized in that the metallic layer is arranged between the carrier film and the white-colored layer.

7. pressure-sensitive adhesive tape according to at least one of the preceding claims, characterized in that the pressure-sensitive adhesive layer on the side facing away from the metallic layer of the carrier film is transparent.

8. Use of a pressure-sensitive adhesive tape according to one of the preceding claims for the production or bonding of optical liquid-crystal data displays.

9. Use according to claim 11 for the bonding of LCD glasses.

10. A liquid crystal data display device comprising a pressure-sensitive adhesive tape according to at least one of claims 1 to 10.