CA2389502A1 - Use of a cast resin and a duroplastic edge seal for producing a sandwich system that consists of a screen and a glass pane - Google Patents

Abstract

The invention relates to the use of a transparent cast resin that consists o f reactive acrylate and methacrylate monomers, acrylate and methacrylate oligomers, bonding agents and initiators. The invention further relates to t he use of an edge seal for producing a sandwich system that consists of a scree n, a cast-resin layer, an edge seal that laterally surrounds the cast-resin lay er and a glass pane.

Description

USE OF A CAST RESIN AND A DUROPLASTIC EDGE
SEAL FOR PRODUCING A SANDWICH SYSTEM THAT
CONSISTS OF A SCREEN SAND A GLASS PANE
The invention relates to the use of a casting resin and to the use of a permanently flexible edge-sealing composition for affixing a sheet of glass to the front of a display screew.
The diagonals of the display screen fronts of cathode-ray tubes have become ever larger in the course of development, In particular in the case of large display screens there is a danger that the display screen will fracture in the event of a shock-like load and an implosion will occur as a consequence. In such a case, viewers may be injured by splinters flying around. It is known to affix a plastic film over the full area of the front of a display screen by way of protection against splinters. In this connection the front of the display screen may be flat or spherically curved.
The object of the invention is to reduce the fracture sensitivity of the front of a display screen and to avoid glass splinters flying around in the event of fracture of the~front of a display screen (flat or spherical).
This object is resolved through the use of a transparent casting resin for the purpose of producing a sandwich arrangement that consists of a display screen, a layer of casting resin and a sheet of glass. The casting resin consists of reactive acrylate and metha.crylate monomers, acrylate and methacrylate oligomers, coupling agents and initiators. In the course of curing, the reactive acrylate and methacrylate monomers form a copolymer which may have a crosslinked structure. The casting resin may, moreover, contain non-reactive acrylate and methacrylate homopolymers and copolymers, plasticisers, tackifying additives and stabilisers. The casting resin contains the aforementioned constituents 5,1 in the following percentages by weight:
a) reactive acrylate and methacrylate 50 -monomers b) acrylate-functional and methacrylate- 1 -functional oligomers c) non-reactive acrylate and methacrylate 0 -homopolymers and copolymers d) fillers 0 -e) plasticisers 0 -f) coupling agents 0.3 -g) photoinitiators 0.01 -h) tackifying additives 0 -i) stabilisers 0 -Use is preferably made of a casting resin that contains the aforementioned constituents in the following percentages by weight:

a) reactive acrylate and methacryla.te 80 -9.7 monomers b) acrylate-functional and methacrylate- 1 -functional oligomers c) non-reactive acrylate and methacrylate 0 -homopolymers and copolymers d) fillers 0 -e) plasticisers 0 -f) coupling agents 0.3 -g) photoinitiators 0.05 -h) tackifying additives 0 -i) stabilisers 0 -3.
Monofunctional and multifunctional, preferably monofunctional, esters of acrylic or methacrylic acid are employed as reactive acrylate and methacrylate monomers (crosslinkers). The alcohol components of the esters that are used may comprise an alkyl group that is substituted with functional groups or that is unsubstituted (such as, for example, methyl, ethyl, n-propyl, iso-propyl, n-butyl, tert.-butyl, pentyl, hexyl, the isomers and higher homologues thereof, such as 2-ethylhexyl, phenoxyethyl, hydroxyethyl, 2-hydroxypropyl, caprolactone hydroxyethyl, polyethylene glycol, polypropylene glycol and dimethylaminoethyl). Also employable as reactive monomers are acrylic and methacrylic acids themselves and the amides of these acids (such as, for example, dimethyl acrylamide or diethyl acrylamide as well as methylethyl acrylamide and acrylonitrile). Mixtures of the reactive acrylate and methacrylate monomers can also be used. Examples of reactive acrylate and methacrylate monomers with one double bond are methyl acry7~ate; methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, i-propyl acrylate, i-propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, i-butyl acrylate, i-butyl methacrylate, i-octyl acrylate, i-octyl methacrylate, n-octyl acrylate, n-octyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, n-decyl acrylate, n-decyl methacrylate, i-decyl acrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, tridecyl methacrylate, phenoxyethyl acrylate, nonylphenol ethoxyacrylate, i3-carboxyethyl acrylate, i-bornyl acrylate, i-bornyl methacrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, dicyclopentenyl acrylate, dicylopentenyloxyethyl acrylate, propylene glycol monoacrylate, propylene glycol monomethacrylate, 2(2-ethoxyethoxy)ethyl acrylate, N-vinylpyrrolidone, 2,3-dihydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacr~rlate, 2-hydroxypropyl acrylate ~or 2-hydroxypropyl methacrylate. Examples of reactive acrylate and methacrylate monomers with two . double bonds are butanediol diacrylate, butanediol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol diacrylate with an average molecular weight of 200, 400 yr 600 g/mol, polyethylene glycol dimethacrylate with an average molecular weight of 200, 400 or 600 g/mol, dipropylene glycol diacrylate or tripropylene glycol diacrylate. Examples of reactive acrylate and methac~ylate,monomers with three double bonds are trimethylolpropane triacrylate, trimethylolpropane methacrylate, pentaerythritol triacrylate, ethoxylated or propoxylated trimethylolpropane triacrylate and also the corresponding methacrylate with an average molecular weight from 430 to 1000 or tris(2-hydroxyethyl)isocyanurate triacrylate. Examples of reactive acrylate and methacrylate monomers with several double bonds are pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate or di(trimethylolpropane) tetraacrylate.
Examples of acrylate-functional and methacrylate-functional oligomers are epoxy acrylates, urethane acrylates, polyester acrylates and silicone acrylates.

The oligomers may be monofunctional or of higher functionality; they are preferably employed in the difunctional form.~~Mixtures of the oligomers can also be used.

Epoxy acrylates are based on bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, each terminated with acrylic or methacrylic acid, on the oligomers thereof, or on novolak glycidyl ether.
Urethane acrylates are synthesised from isocyanates (e. g. toluylene, tetramethylxylylene, hexamethylene, isophorone, cyclohexylmethane, trimethylhexamethylene, xylylene or diphenylmethane diisocyanates) and polyols and are functionalised with hydroxy acrylates (e.g. 2-hydroxyethyl acrylate) or hydroxy methacrylates (e. g.
hydroxyethyl methacrylate).
The polyols may be polyester polyols or polyether polyols. Polyester,polyols can be produced from a dicarboxylic acid or from a mixture of several dicarboxylic acids, preferably from a dicarboxylic acid (e. g. adipic acid, phthalic acid or the anhydrides thereof) and one or more diols or polyols, preferably from a mixture of a diol with a triol (e. g. 1,6-hexanediol, 1,2-propanediol, neopentyl glycol, 1,2,3-propanetriol, trimethylolpropane, pentaerythritol or ethylene glycols such as diethylene glycol). Polyester polyols can also be obtained by reaction of a hydroxycarboxylic acid (e. g. starting from caprolactone) with itself. Polyether polyols can be produced by etherification of a diol or polyol with ethylene oxide or propylene oxide.

Polyester acrylates are the polyester polyols described above which are functionalised with acrylic acid or with methacrylic acid.
S The silicone acrylates that are used here and known as such are based on poly(dimethylsiloxanes) of varying molecular weight which are functionalised with acrylate.
Non-reactive acrylate or methacrylate homopolymers and copolymers are homopolymers and copolymers of acrylic acid, of methacrylic acid and of the-esters of these acids previously described. The casting resin may also contain mixtures of the stated homopolymers and copolymers. The casting resin can also be produced without non-reactive acrylate and methacrylate homopolymers and copolymers.
Fillers may be reinforcing and non-reinforcing.
Employable as fillers are pyrogenic or precipitated silicic acids, which are preferably hy~.rophilic and/or surface-treated, and cellulose derivatives such as cellulose acetates, cellulose acetobutyrates, cellulose acetopropionates, methylcellulose and hydroxypropyl methylcellulose. The casting resin may also contain mixtures of the stated fillers. The casting resin may also be produced without fillers.
Examples of plasticisers are esters of phthalic acid, such as di-2-ethylhexyl, diisodecyl, diisobutyl, dicyclohexyl and dimethyl phthalate, esters of phosphoric acid, such as 2-ethylhexyldiphenyl, tri~(2-ethylhexyl) and tricresyl phosphate, esters of trimellitic acid, such as tri(2-ethylhexyl) and triisononyl trimellitate, esters of citric acid, such as acetyltributyl and acetyltriethyl citrate, and esters of dicarboxylic acids, such as di-2-ethylhexyl adipate and dibutyl sebacate. The casting resin may also contain mixtures of the stated plasticisers. The casting resin can also be produced without plasticisers.
Coupling agents may be selected from the group of organofunctional silanes, such as 3-glycidyloxypropyl trialkoxysilane, 3-aminopropyl trialkoxysilane, N-aminoethyl-3-aminopropyl trialkoxysilane, 3-methacryloxypropyl trialkoxysilane, vinyl trialkoxysilane, iso-butyl trialkoxysilane, mercaptopropyl trialkoxysilane, and from the group of silicic esters, such as tetraalkyl orthosilicate. The casting resin may also contain mixtures of the stated coupling agents.
Employable as photoinitiators are compounds from the group of benzoin ethers, the group of benzil ketals, the group of a-dialkoxyacetophenones, the group of a-hydroxyalkylphenone~, the group of a-aminoalkylphenones, the group of acyl phosphine oxides, the group of benzophenones or the group of thioxanthones or mixtures thereof. Examples are 2-hydroxy-2-methyl-1-phenylpropanone-1, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl phosphine oxide, 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinoph:enyl)butanone-1, 1-hydroxycyclohexyl phenyl ketone, benzophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, and 2-methyl-1-[4-(methylthio)phenyll-2-morpholonopropanone-1.
Tackifying additives may be selected from the group of natural and synthetic resins, as well as such resins which have been subsequently modified. Usable as resins are hydrocarbon resins, colophony and the derivatives thereof, polyterpenes and the derivatives thereof, coumarone/indene resins, phenolic resins, polybutenes, hydrated polybutenes, polyisobutenes and hydrated polyisobutenes. The casting resin may also contain mixtures of the stated tackifying additives. The casting resin may also be produced without tackifying additives.
Stabilisers may be anti-oxidants such as phenols (e. g,.
4-methoxyphenol) or sterically hindered phenols (e. g.
2,6-di-tert.-butyl-4-methylphenol) or may be mixtures of various anti-oxidants. The casting resin may also be produced without stabilisers.
A casting resin that has been adjusted to have low viscosity, preferably, finds application, since this is particularly suitable for the processing, i.e. the rational casting process. The viscosity, measured at 23 °C, lies within the range from 1 mPa.s to 1000 mPa.s, preferably within tile range from l mPa.s to 500-mPa.s and, in particularly preferred manner, within the range from 1 mPa.s to 100 mPa.s (measured using a Rheolab MC20 rotational viscometer manufactured by Physica with a MK20/157 cone (25 mm diameter, 1°) with a velocity gradient of D = 40 1/s). Curing of the casting resin is carried out with UV light. In this process the casting resin is transformed into a polymer film that is as transparent and colourless as possible.
Use is. preferably made of a casting resin, the transparency of which in the cured state (measured with a measuring instrument manufactured by Byk, type Hazegard XL-211, in respect of samples having a structure of 4 mm float glass / 2 mm casting resin / _ 4 mm float glass) lies within a range from 0.01 haze to 2 haze, preferably within a range from 0.01 haze to 1 haze and, in particularly preferred manner, within a range from 0.01 haze to 0.5 haze.
Use is preferably made of a casting resin, the colour of which in the cured stated (measured with a spectrophotometer manufactured by Perkin Elmer, type Lambda 12, in~respect of samples having a structure of 4 mm float glass / 2 mm casting resin / 4 mm float glass? lies within a range of L" 50 to 99, a* -10 to 10, b* -10 to 10, preferably within a range of L* 80 to 99, a* -5 to 5, b* -5 to 5 and, in particularly preferred manner, within a range of L* 90 to 99, a* -5 to 0, b* -1 to 2. These data relate to a measuremerit with standardized light D65 and with a 2° standard observer.
The casting resin that is used is produced by mixing the constituents in a suitable unit. When high shear forces are necessary for the destruction of filler agglomerates in the course of mixing, the unit may be a planetary dissolves with a dissolves disc rotating at high speed.
Whenever high shear forces are not required in the course of mixing, the unit may be a stirring vessel with a paddle mixer or turbulence mixer. Whether high or low shear forces are required depends upon the constituents that are used. For instance, a dissolves disc is definitely necessary for the purpose of incorporating pyrogenic silicic acid into a liquid. In the case of low.viscosities, the use of a bead mill may become necessary.
The viscosity rises significantly as a result of admixture of fillers. The use of a vacuum or a protective gas may be necessary in the course of the -mixing process.

The mixing-temperature is around room temperature at the start of mixing and may rise as high as 70 °C, depending on the consistency of the mixture and on the energy input of the mixing unit that is. used. In the case 5 where use is made of low-boiling monomers such as methyl methacrylate, for example, cooling may be necessary.
On use, according to the invention, of the casting resin, a sandwich arrangement is produced consisting of 10 a display screen, a layer of casting resin and a pane of glass. The production of the sandwich arrangement can be divided up into the following individual process steps:
1. Cleaning and drying of the display screen and of the sheet of glass 2. Application of an edge seal (either onto the front of the display screen or onto the sheet of glass, preferably onto the front of the display screen) 3. Congruent placing of the sheet of glass onto the front of the display screen 4. Pressing of the composite obtained, consisting of display screen and sheet of glass, to the desired distance between display screen and sheet of glass 5. Charging of the casting resin 6. De-aeration of the interspace and sealing of the charging opening 7. Inspection of the interspace filled with casting resin for freedom from air bubbles m 8. Curing of the casting resin by irradiation with W
light 9. Final inspection of the finished sandwich arrangement The individual working steps may be executed as follows:
Cleaning and drying of the front of the display screen and of the sheet of glass are effected in a manner known as such with the aid of commercial glass detergents.
This may preferably take place automatically in a washing machine. After the washing, the sheets of glass have to be absolutely dry, grease-free and free of , detergent residues. An inspection for cleanliness is an advantage. This can be effected visually, in the case of the sheet of glass in terms of transmitted light, and with respect to the front of the display screen in terms of reflection with the aid of fluorescent tubes. In the course of the previous cutting to size of the sheet of glass, working takes place advantageously with water-soluble cutting oils or with cutting oils that dry without leaving a residue.
Sealing of the edge can be undertaken by means of a double-sided adhesive tape or preferably by means of a permanently flexible material (edge-sealing compound) that possesses thermoplastic properties and that, after being fused, is applied in the form of a bead or strand onto the front of the display screen or onto the sheet of glass .
The edge seal that is used has to be compatible with the casting resin that is used, i.e. no chemical reactions are permitted to take place between the edge seal and the casting resin, and there has to be mechanical compatibility. To this end, the adhesive force per unit area of the casting resin in the course of. curing must be greater than the yield-point of the edge. seal at room temperature. This ensures that undesirable separations do not occur.
Usable as adhesive tape, are, for example, acrylate foam tapes coated on both sides with contact adhesive, such as, for example, Acrylic Foam Tape type 4951, 4611 or 4945/4664 manufactured by 3M, or polyurethane foam tapes coated on both sides with contact adhesive, manufactured, for example, by Nordson, or transparent inherently tacky acrylate tapes, such as, for example, Acrylic Tape type 4910 or 4915 manufactured by 3M. The adhesive tapes are between 3 mm and 9 mm wide, preferably 6 mm wide, and 1 mm to 2 mm thick, preferably 1.2 mm to 1.5 mm thick. By reason of their softness, the transparent acrylate tapes offer advantages over. the foam tapes with respect to their compressibility. This is due to the fact that the casting resins that are provided for use exhibit a contraction in volume of between 5 % and 17 % in the course of curing. As a result of this contraction, stresses are formed in the layer of casting resin during curing. The greater the contraction in volume of the casting resin, the more uneven the thicknesses of the glass over the surf ace, the thicker the sheet of glass and, above all, the harder and more elastic the edge seal, the greater are these stresses.
Congruent placement of the sheet of glass onto the front of the display screen, pressing of the composite obtained - consisting of display screen and sheet of glass - to the desired distance, charging of the casting resin, de-aeration of the interspace and sealing of the charging opening are effected in conventional manner.
Filling is preferably effected by means of flat nozzles made of thin stainless-steel sheet with a thickness of less than 0.2 mm and a width of 50 mm maximum, preferably 20 mm max. This filling is effected from above, with.a slightly inclined position of the sandwich arrangement,. or from below, by a small aluminium nozzle (consisting of aluminium sheet with a thickness of max.
0.2 mm) being secured in position with adhesive. This nozzle is about 5 mm wide and 1 mm thick and has a rectangular to oval shape at the point where it is adhesion-bonded within the sandwich arrangement.
However, filling is preferably undertaken from above.
After filling, the sandwich arrangement is preferably de-aerated in such a manner that the sandwich arrangement is brought slowly out of the inclined position into the hprizontal position. After de-aeration, the charging opening is sealed. This can be carried out with the thermoplastic edge-sealing composition itself or with a hot-melt adhesive based on, for example, ethylene/vinyl-acetate copolymer.
The sandwich arrangement, which is not yet cured, is inspected for air bubbles which may possibly still be present. These can be removed with a cannula, for example.
Curing of the casting resin is effected with W light.
With the photoinitiators that are used here, low-pressure tubes in blacklight blue have proved very suitable for this purpose. These tubes have low current consumption. Several tubes are arranged in such a way that a homogeneously illuminated radiation field arises.
With a radiant power {integral value 200 nm to 400 nm)of from 15 W/m2 to 25 W/m2, measured with a measuring instrument manufactured by Heraeus, Radialux type, the required irradiation-time until curing is complete~lies within the range from 3 minutes to 20 minutes. The precise value depends on the casting-resin mixture that is used.
By reason of the poor planarity of display screens differing with respect to float glass, undesirable stresses may arise in the course of the production of display-screen sandwich arrangements with an adhesive tape as edge seal.
Considered as a model, the edge seal can be imagined as a spring and/or damper. In the case,of a spring, it is compressed by the polymerisation shrinkage of the casting resin during curing. The spring is permanently 20 under pressure, and the adjacent polymeric casting-resin interlayer is permanently under tension. This means that during the entire operating life of the sandwich arrangement the polymeric casting-resin interlayer has to accommodate a static load due to the spring and the 25 polymerisation shrinkage. Adhesive tapes that are adhesive on both sides represent a combination of spring and damper. This means that in the event of a tensile force on the display screen and the sheet of glass which is applied permanently by the polymerisation shrinkage, some of this force has the effect of deforming the edge seal. In the model, the damping properties of the edge seal are responsible for this.
Nevertheless, on account of the flexing properties of the adhesive tapes, a residual compressive force is preserved. The viscous portion of the edge seal is responsible fox the damping properties, and the elastic portion is responsible for the flexing properties. This means that the elastomer from which the adhesive tape is 5 synthesised has viscoelastic properties.
An edge seal that acts as little as possible as a spring and as much as possible as a damper is desirable in order to be able to reduce the polymerisation-shrinkage 10 forces as much as possible.
This object is achieved through the use of an edge seal that consists of a composition which is permanently flexible at room temperature, which possesses I5 thermoplastic properties and which, after being fused, is applied in the form of a bead or strand onto the front of the display screen or onto the sheet of glass.
The edge-sealing composition that is used preferably consists of a base polymer and optionally further constituents.
The base polymer may consist of a homopolyrner, copolymer or terpolymer of isobutylene or a mixture thereof or of a homopolymer and/or copolymer of acrylates and/or methacrylates or mixtures thereof.
Further constituents may be thermoplastic polymers, natural and synthetic rubbers, tackifying additives, plasticisers, coupling agents, reinforcing and non-reinforcing fillers, stabilisers and other additives.
An edge-sealing composition that is preferably used contains the base polymer and the further constituents 35. in the following percentages by weight:

a) base polymer 30 - 100 b) thermoplastic polymers 0 - 50 c) natural and synthetic rubbers 0 - 50 d} tackifying additives . 0, - 30 e) plasticisers 0 - 50 _ f} coupling agents 0 - 5 g) stabilisers 0 - 5 h) reinforcing and non-reinforcing fillers 0 - 70 The edge-sealing composition that is used particularly preferably contains the base polymers~and the further constituents in the following percentages by weight:
a) base polymer 40 - 100 b) thermoplastic polymers 0 - 30 c) natural and synthetic rubbers 0 - 30 d) tackifying additives 0 - 25 e) plasticisers 0 - 30 f) coupling agents 0 - 3 g) stabilisers 0 - 3 h) reinforcing arid non-reinforcing fillers 0 ~ - 60 Homopolymers of isobutylene are polyisobutylenes which are commercially available in various molecular-weight ranges. Examples of polyisobutylene trade names are Oppanol (BASF AG) , Vistanex (Exxon) or Efrolen (Efremov). The state of the polyisobutylenes ranges from liquid via soft-resin-like to rubber-like. The molecular-weight ranges may be stated as follows: the number average of the molar mass amounts to 2000 to 1,000,000 g/mol, preferably 24,000 to 600,000 g/mol, and the viscosity average of the molar mass amounts to 5000 to 6,000,000 g/mol, preferably 40,000 to 4,000,000 g/mol.

Copolymers and terpolymers of isobutylene contain as comonomers and termonomers, 1,3-dimes such as isoprene, butadiene, chloroprene or i3-pinene, functional vinyl compounds such as styrene, a-methylstyrene, p-methylstyrene or divinylbenzene, or further monomers.
An example of a copolymer formed from isobutylene and . isoprene is butyl rubber with small proportions of isoprene; commercially available are, for example, diverse butyl types manufactured by Bayer AG, Exxon Chemical or Kautschuk-Gesellschaft. Terpolymers of isobutylene with the monomers isoprene and divinylbenzene result in partially crosslinked butyl-rubber types which are also obtainable by subsequent crosslinking of butyl rubber; commercially available >
are, for example, LC Butyl manufactured by Exxon Chemical, Kalar manufactured by Hardman, or Polysar Butyl XL manufactured by Bayer AG. The homopolymers, copolymers and terpolymers of isobutylene may also be subjected to subsequent chemical modification; known is the conversion of butyl rubber with halogens (chlorine, bromine), which results in chlorobutyl rubber or bromobutyl rubber. The conversion with bromine of a copolymer formed from isobutylene and p-methylstyrene- to give the terpolymer formed from isobutylene, p-methylstyrene and p-bromomethylstyrene, which is commercially available under the trade name EXXPRO
manufactured by Exxon Chemical, takes place in similar manner.
Homopolymers or copolymers of acrylates or methacrylates (poly(meth)acrylates) are polymers of the esters of acrylic or methacrylic acid and may, for example, comprise by way of alcohol component an alkyl group that is substituted with functional groups or that is unsubstituted, for example methyl, ethyl, propyl, iso-is propyl, n-butyl, iso-butyl, tert.-butyl, pentyl and hexyl and the isomers and higher homologues thereof, 2-ethylhexyl, phenoxyethyl, hydroxyethyl, 2-hydroxypropyl, caprolactone hydroxyethyl, dimethylaminoethyl. Also included are polymers of acrylic acid, of methacrylic acid, of amides of the stated acids and of acrylonitrile. Use may also be made of partially crosslinked poly(meth)acrylates in which crosslinking is effected via a polyfunctional monomer with, for example, diethylene glycol or trimethylolpropane by way of alcohol component, and mixtures of the polyacrylates and polymethacrylates.
Examples of thermoplastic polymers are polyolefins as .
homopolymers and copolymers, and synthesised from the monomers ethylene, propylene, n-butene and the higher homologues and isomers thereof and from functional vinyl compounds such as vinyl acetate, vinyl chloride, styrene and a-methylstyrene. Further examples are polyamides, polyimides, polyacetals, polycarbonates, polyesters and .polyurethanes and mixtures of the aforementioned polymers. However, the edge-sealing composition to be used in accordance with the invention can also be produced without thermoplastic polymers.
Natural and synthetic rubbers may be selected from the group of homopolymers of dienes, the group of copolymers and terpolymers of dienes with olefins, and the group of copolymers of olefins. Examples are polybutadiene, polyisoprene, polychloroprene, styrene/butadiene rubber, block copolymers with blocks consisting of styrene and butadiene or isoprene, ethylene/vinyl-acetate rubber, ethylene/propylene rubber and ethylene/propylene/diene rubber, for example with dicyclopentadiene or ethylidene norbornene as dime component. The rubbers may also be employed in hydrogenated form and also in mixtures.
However, the edge-sealing composition to be used in accordance with the invention can also be produced without rubbers.
Tackifying additives may be selected from the group of natural and synthetic resins, as well as those which have been subsequently modified, which comprise, inter alia, hydrocarbon resins, colophony and derivatives .
thereof, polyterpenes and derivatives thereof, coumarone/indene resins and phenolic resins, and from the group of polybutenes, polyisobutenes and degraded liquid rubbers (e.g. butyl rubber or EPDM), which may also be hydrogenated. Mixtures of the listed tackifying, additives may also be employed. However, the edge-sealing composition to be used in accordance with the invention can also be produced without tackifying additives.
Examples of plasticisers are esters of phthalic acid (e.g. di-2-ethylhexyl, diisodecyl, diisobutyl or dicyclohexyl phthalate), of phosphoric acid (e.g. 2-ethylhexyldiphenyl, tri(2-ethylhexyl) ar tricresyl phosphate), of trimellitic acid (e. g. tri(2-ethylhexyl) or triisononyl trimellitate), of citric acid (e. g.
acetyltributyl or acetyltriethyl citrate) or of dicarboxylic acids (e.g. di-2-ethylhexyl adipate or dibutyl sebacate). Mixtures of the plasticisers may also be employed. However, the edge-sealing composition to be used in accordance with the invention can also be produced without plasticisers.
Coupling substances may be selected from the group of silanes, which, for example, may comprise 3-glycidyloxypropyl trialkoxysilane, 3-aminopropyl trialkoxysilane, N-aminoethyl-3-aminopropyl trialkoxysilane, 3-methacryloxypropyl trialkoxysilane, vinyl trialkoxysilane, isobutyl trialkoxysilane, 3-mercaptopropyl trialkoxysilane, from the group of S silicic esters, for example tetraalkyl orthosilicates, and from the group of metallates, for example tetraalkyl titanates or tetraalkyl zirconates, as well as mixtures of the listed coupling substances. However, the edge-sealing composition to be used in accordance with the invention can also be produced without coupling substances.
Stabilisers may be anti-oxidants of the type represented by the sterically hindered phenols (e. g.
tetrakis(methylene-3-(3,5-di-tert.-butyl-4-hydroxyphenyl)propionate]methane) or of the type represented by the sulfur-based anti-oxidants such as mercaptans, sulfides, polysulfides, thiourea, mercaptals, thioaldehydes, thioketones etc, or UV-blocking agents of the type represented by benzotriazoles, benzophenones or of the HALS type (Hindered Amine Light Stabiliser) or anti-ozonants.
These may be employed either on their own or in mixtures. However, the edge-sealing composition to be used in accordance with the invention can also be produced without stabilisers.
Examples of reinforcing and non-reinforcing fillers are pyrogenic or precipitated silicic acid, silica gel, precipitated or ground chalk (also surface-treated), calcium oxide, clay, kaolin, talc, quartz, zeolites, titanium oxide, glass fibres or aluminium and zinc powders and mixtures thereof. If a dark colour of edge seal according to the invention is not considered to be annoying, carbon black, carbon fibres or graphite can also be employed. However, the edge-sealing composition to be used in accordance with the invention can also be produced without fillers.
A preferred edge seal has a yield-point of a maximum of 4000 Pa, particularly preferably a maximum of 2000 Pa, at 120 °C (measured with a rheometer having plate/p~.ate geometry, measuring-plate diameter 25 cm, measurement in oscillation at oscillation frequency 1 Hz, torque range from 0.1 mNm to 100 mNm, shear rate from 10-4 s-1 to 1 s-1) .
The edge-sealing composition to be used in accordance with the invention is produced by mixing the base t 15' polymer in a suitable unit. Further constituents which are described above may also be admixed. If high shear forces are required, the mixing unit may be, for example, a kneader, a twin-screw extruder or a single-screw extruder. If high shear forces are not needed;
mixing may take place in a planetary dissolver,~in a paddle mixer with a dissolver disc, in a turbulence mixer or in similar units. Whether high or low shear forces are needed depends upon the consistency of the initial materials and of the particular product; thus high shear forces are needed for the purpose of incorporating rubbers or reinforcing fillers.
The mixing-temperature lies within the region from 40 °C
to 200 °C, preferably within the region between 70 °C and 180 °C. Mixing can optionally be carried out under protective gas or in a vacuum.
After being fused, the thermoplastic edge-sealing composition is applied in the form of~a bead or strand onto the front of the display screen or onto the sheet of glass by means of known processing units (e.g. a conventional hot-melt-adhesive application unit or extruders) at temperatures within the region between 40 °C and 200 °C, preferably between 70 °C and 180 °C,.
The crass-sectional shape of the bead or of the strand may be rectangular with a rounded shape for the short side, triangular, circular or oval.
The circular to oval shape has turned out to be particularly favourable, since, by, reason of the smaller surface of contact with the glass surface, the thermoplastic edge-sealing composition cools more slowly and, as a result, pressing of the sandwich arrangement is possible with less pressure. This is necessary in particular when the sheet of glass is thinner than 2 mm, since otherwise the glass could break in the course of pressing thin glasses as a result of excessive pressure.
Depending on the charging method provided, a charging opening of, for example, 10 mm to 70 mm for the casting resin is left at the corner of one longitudinal side.
After application of the edge-sealing composition, the sheet of glass is laid congruently onto the front of the display screen. The thickness of the edge seal is adjusted by means of pressing in such a way that the thickness of the layer of casting resin does not fall below the value of 0.2 mm, preferably 0.5 mm, at any point in the sandwich arrangement.
The edge-sealing composition to be used in accordance with the invention has the advantage that it exhibits the requisite chemical and mechanical compatibility with the casting resin.

Since the yield-point of the edge-sealing composition to be used in accordance with the invention is dependent on the temperature, after curing, of the sandwich arrangement, it is an advantage to temper said arrangement.
The advantage of the use, according to the invention, of the casting resin that has been described lies in the reduced fracture sensitivity of the display screens that are produced in such a way. As a result of the simultaneous use, according to the invention, of the edge seal that has been described, it is possible for the fracture sensitivity of the display screen to be reduced still more. The invention is of significance, in particular, in connection with the production of flat display screens having reduced fracture sensitivity.
The subject-matter of the invention will be explained in more detail on the basis of the following Examples.
Example 1: Synthesis of a base polymer based on poly(meth)acrylate by means of W polymerisation, the base polymer being for the subsequent production of an edge-sealing composition.
0.8 g (0.4 % relative to monomers) of benzyl dimethyl ketal were added to 200 g of a mixture of 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate and acrylic acid (weight ratio: 65:33:2). The mixture was passed into a composite consisting of a Teflon plate and a polyester film provided with an non-stick coating (Hostaphan, manufactured by Hoechst), which was sealed in the marginal region by an adhesive tape coated on both sides with contact adhesive and having a thickness of 2 mm, and was polymerised in 20 minutes by being subjected to W irradiation (tube type: Philips TL 36 W/08).
Example 2: Production of an edge-sealing composition based on poly(meth)acrylate 60 g .(69.0 %) of the base polymer from Example 1 were kneaded in a kneader heated to 130°C for 60 minutes with 6 g (6.9 %) of highly dispersed silicic acid (filler), 20 g (23.0 %) of an acrylate resin (Jagotex AP 273 manufactured by Jager, tackifying additive) and 1 g (1.1 %) of tetrakis[methylene-3-'(3,5-di-tert.-butyl-4-hydroxyphenyl)propionate]methane (Ralox 630 manufactured by Raschig, stabiliser). Then a vacuum was applied for >
30 minutes at 130 °C, and subsequently the composition was filled into a cartridge.
Example 3: Production of an edge-sealing composition based on isobutylene polymers ' 997.5 g (47.5 %) of polyisobutylene (Vistanex LM-H
manufactured by Exxon, base polymer) and 52.5 g (2.5 %) of butyl rubber (Butyl 065 manufactured by Exxon, rubber) were kneaded in a kneader heated to 150 °C for 60 minutes with 382.2 g (18.2 %) of carbon black (Corax N 330 manufactured by Degussa, filler), 226.8 g (10.8 %)of chalk (Omya 95T manufactured by Omya, filler), 336.0 g of (16.0 %) zeolite (Baylith L
manufactured by Bayer, filler), 100.8 g (4.8 %) of talc (Fintalc M10 manufactured by Omya, filler) and 4.2 g (0.'2 %) of tetrakis[methylene-3-(3,5-di-tert.-butyl-4-hydroxyphenyl)propionate]methane (Ralox 630 manufactured by Raschig, .stabiliser). Then a vacuum was applied for over 2 hours at 150 °C and subsequently the composition was removed from the kneader. A strand having a diameter of 3.3 mm was generated on extrusion of this composition at 130 °C through a round nozzle.
Example 4: Production of a casting resin 1184.0 g (74.0 %) of 2-ethylhexyl acrylate and 200.0 g (12.5 %) of acrylic acid, as reactive acrylate monomers 120.0 g (7.5 %) of benzyl-2-ethylhexyl adipate (Adimoll BO manufactured by Bayer) as plasticiser and 11.2 g 10 (0.7 %) of 3-glycidyloxypropyl trimethoxysilane (Dynasilan GLYMO manufactured by Sivento) as coupling agent were supplied to a 2000m1 glass beaker, and these were mixed with a propeller stirrer over a period of 10 minutes. Then 80.0 g (5.0 %) of an aliphatic 15 urethane acrylate (Craynor CN 965 manufactured by Cray Valley) were mixed in within 15 minutes as acrylate-functional oligomer. Finally, 4:8 g (0.3 %) of oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone]
(Esacure KIP 150 manufactured by Lamberti) were added as 20 photoinitiator, and:the mixture was homogenised for 10 minutes.
Example 5: Production of a casting resin 25 944.8 g (56.55 %)of 2-ethylhexyl acrylate, 224.0 g (14.0 %) of n-butyl acrylate and 224.0 g (14.0 %) of acrylic acid as reactive acrylate monomers, 200.0 g (12.5 %) of diphenylcresyl phosphate (Disflamoll DPK
manufactured by Bayer) as plasticiser, 4.8 g (0.3 %) of 30~ vinyl trimethoxysilane (Dynasilan VTMO manufactured by Sivento) as coupling agent, 40.0 g (2.5 %) of an aliphatic urethane acrylate (Craynor CN 985 manufactured by Cray Valley) as acrylate-functional oligomer and 2.4 g (0.15 %) of 1-hydroxycyclohexyl phenyl ketone) (Irgacure 184 manufactured by Ciba Spezialitatenchemie) as photoinitiator were supplied to a 2000 m1 polyethylene wide-necked bottle, and these were homogenised over a period of 30 minutes with the aid of a magnetic stirring rod and a magnetic stirring motor.
Example 6: Production of a casting resin 874.4 g (54.65 %) of 2-ethylhexyl acrylate and 240.0 g (15.0 %) of acrylic acid as reactive acrylate monomers, 160.0 g .(10 %) of tricresyl phosphate (Disflamoll TKP
manufactured by Bayer) as plasticiser, 4.8 g (0:3 %) of y-methacryloxypropyl trimethoxysilane (Dynasilan MEMO
manufactured by Sivento) as coupling agent and 0.8 g (0.05 %) of benzil dimethyl ketal (Lucirin BDK
manufactured by BASF) as photoinitiator were supplied to a 3000 ml glass beaker, and these were mixed for 15 minutes with a propeller stirrer. Subsequently, 320.0 g (20.0 %) of an aliphatic urethane acrylate (Genomer 4215 manufactured by Rahn) as acrylate-functional oligomer~heated to 40 °C were added slowly subject to vigorous stirring, and the mixture was homogenised over a period of 20 minutes.
Example 7: Determination of the curing-time of the casting resins from Examples 4 to 6 on W irradiation through float glass A foamed acrylate tape 2 mm thick and 6 mm wide, adhesive on both sides (Acrylic Foam Tape 4912 manufactured by 3M), was placed on a cleaned float-glass plate 4 mm thick having the dimensions 300 mm x 300 mm peripherally on the edge of the glass plate in such a way that a gap of about 50 mm remained between the ends of the tape as charging opening for the casting resin. --Then a second, cleaned glass plate 3 mm thick was placed in position congruently and this arrangement was pressed by hand.
Into each composite produced in this way was charged one of the casting resins from Examples 4 to 6 at an angle of about 80°, charging being by means of a polyethylene hose as far as the. charging opening at the edge, and the edge openings were sealed with an ethylene/vinyl-acetate hot-melt.adhesive (Hei~schmelzkleber 22 manufactured by Chemetall).
The sandwich arrangements were cured under a W-Himmel manufactured by Torgauer Machinenbau GmbH by irradiation with blacklight tubes of the type TZ-D 36W/08 =
manufactured by Philips, the UV radiant power on the surface of the glass amounting to 20 W/m2. With a view to determining the curing-time, the temperature during the W irradiation was measured with a temperature sensor PT 100 on the pane of float glass with a thickness of 4 mm facing away from the UV tubes and was recorded with an x/y plotter. The initial temperature at the start of the W irradiation was 23 °C.
The results are presented in Table 1.
Example 8: Determination of the curing-time on W
irradiation through grey-coloured cover glass with a transmission of 60 Example 7 was repeated with the casting resins from Examples 4 to 6, with, instead of the second pane of float glass, use being made in each instance of a grey-dyed glass plate with a transmission of 60 %. In the course of curing of the respective composite, the coloured glass plate faced towards the UV tubes.

The results are presented in Table 1.
Table 1: Curing-times of the casting resins from Examples 4 to 6, measured in accordance with~Examples 7 and 8 CLring-times cl~ring-times from Example from example 7 (irradiation B (irradiation throw h throw h float -d ed leas 3 lass 3 mn thick) mm thick) Time (mintTemperatureIrradiationTime (miniTemperatureIrradiation until until temperaturemaximumtime temperaturemaximumtime maximum f'C1 (mini maximum !'C1 Imial Casting resin 1 from 1e 10.5 T2 20 16.0 70 25 Casting resin from 1n 10.5 80 ZO 17.5 19 30 Casting resin .

from scam7.5 77 15 13.5 7s 25 1e 6 Example 9: Determination of the haze value for the casting resins from Examples 4 to 6 The haze value indicates the percentage of transmitted light that is deflected away from the direction. of the incident light in the course of transradiation of a sample as a result of forward scattering. Only the light flux with a deflection of more than 2.5° is considered as haze.
The measurement was carried out at 23 °C in respect of the samples produced in accordance with Example 7 with the casting resins from Examples 4 to 6 using a Hazegard-System XL211 manufactured by Gardner. The results are presented in Table 2.
Table 2: Haze values in respect of the structure 3 mm float glass / 2 mm casting resin / 4 mm float glass Casting resin Casting resin Casting resin from from from Example 4 Exa 1e 5 Exam 1e 6 Raze value0.13 0.17 0.10 Example 10: Production of casting-resin films for ascertaining the mechanical properties A thin polyester film was firstly placed onto a float-glass plate 4 mm thick moistened with water and having the dimensions 300 mm x 300 mm and was smoothed, and then a foamed acrylate tape, 2 mm thick and 6 mm wide, adhesive on both sides (Acrylic Foam Tape 4912 manufactured by 3M), was affixed peripherally in the marginal region of the polyester film in such a way that .
a gap of about 50 mm remained from the ends of the tape.
Then a second glass plate 4 mm thick, likewise with a polyester film applied to it, was placed in position congruently and this arrangement was pressed by hand.
Each composite produced in this way was clamped at all four corners and was filled with a casting resin according to each of Examples 4 to 6 at an angle of about 80° by means of a PE tube via the charging opening at the edge, and the edge opening was sealed with an ethylene/vinyl-acetate hot-melt adhesive (Heif3schmelzkleber 21 manufactured by Chemetall).
Curing was effected with blacklight tubes in a manner analogous to Example 7.
After cooling to room temperature, the polyester films were peeled off from the cured casting-resin films in order to ascertain some mechanical properties of the cured casting resins.
Example 11: Determination of the Shore-A hardness of the cured casting resins according to Examples 4 to 6 Three segments with a size of 40 mm x 40 mm were cut out of the casting-resin films produced in accordance with Example 10, were placed on one another congruently, resulting in a sample thickness of about 6 mm, and were 5 sprinkled with talc,. Testing of the~Shore-A hardness was effected 24 h after production of the films iri accordance with DIN 53505. The results are presented in Table 3.
10 Example 12: Determination of the inherent strength of the cured casting resins according to Examples 4 to 6 After storage at room temperature for 24 h, the tensile strengths, elongations at tear and tensile stresses >
15 according to DIN 53504 in respect of the casting-resin films produced in accordance with Example 10 were ascertained with a Zwick universal,testing machine at a drawing speed of 100 mm/min on an S2 standard rod at 23 °C. The results are presented in Table 3.
20 . ' Table 3: Mechanical properties of the casting resins from Examples 4 to 6 2 Casting Casting Casting resin 5 resin resin from Exa from Exa from Example1e 6 1e 4 5 Shore-A hardness 16 13 47 Tensile stress 25 0.11 0.09 0.42 % IMPa]

Tensile stress 50 0.17 0.13 0.66 % [MPa1 Tensile stress 100 0.26 ' 0.18 1.22 it (MPa]

3 Elon ation (%1 259 419 130 Tensile atren th 0.95 1.28 1.81 [MPa]

Example 13: Determination of the shrinkage of the casting resins from Examples 4 to 6 on polymerisation.

The expression 'shrinkage of the casting resins of polymerisation' is to be understood to mean the difference in volume in percentage terms before and after curing.
With a view to determining the shrinkage on polymerisation, in each instance the density of the liquid mixtures and, after curing, the density in respect of film segments of the casting resins from Examples 4 to 6 at 20 °C was ascertained with a spindle using a Sartorius RC 250 S balance with special structure in accordance with the buoyancy principle by weighing in air and in ethanol.
The polymerisation shrinkage was calculated in accordance with the formula [1/p liq - 1/p film]*100 /
[1/p liq], where p 1iq signifies the density of the liquid casting resin and p film signifies the density of the cured casting resin. The results are presented in Table 4.
Table 4: Density and shrinkage of the casting resins on polymerisation Casting resinCasting resinCasting resin from from from Exam 1e 4 Exa 1e 5 Example 6 Density of the 0.923 0.944 0.977 liquid castin resin [ /ml) Density of the 1.031 1.066 1.084 cured 3 castin resin 0 ( /cm') Shrinkage on 10.5 ~ 11.5 ~ 9.9 ~

polymerisation [t) Example 14: Determination of the viscosity of the casting resins from Examples 4 to 6 The viscosities of the casting resins of Examples 4 to 6 were ascertained using a rotational viscometer (Rheolab MC20 manufactured by Physics) with a MK20/157 cone (25 mm diameter, 1°) with a velocity gradient of D = 40.
1/s at 20 °C. The results are presented in Table 5.
Table 5: Viscosities of the casting resins Casting resinCasting resinCasting resin from from from Exa 1e 4 Exat~le 5 Exa 1e 6 ' 1 Viscoait [mPas]3.4 2.3 17.6 Example 15: Production of a sandwich arrangement consisting of display screen, edge seal from Example~2, 20~ casting resin from Example 4 and sheet of glass The edge-sealing composition from Example 2 was applied peripherally to a cleaned, grey-stained front sheet of glass (transmission 60°s) in the form of a strand having 25 a diameter of about 4mm using a heatable cartridge gun at 150°C in such a way that an opening 50 mm wide for the filling with casting resin remained between the start and the end of application. Directly after application of the edge-sealing composition, the front sheet of 30 glass was placed on a cleaned flat display screen (32 inch, 16:9 format) and was pressed to such an extent by loading to 80 kg that a gap of about 1 mm was obtained in the centre of the arrangement between the front glass and the surface of the flat display screen.

Tnto this composite the casting resin from Example 4 was charged at an angle of about 30° by means of a PE tube . via the edge opening as far as the charging opening, and the opening was sealed with an ethylene/vinyl-acetate hot-melt adhesive (Heif~schmelzkleber~21 manufactured by Chemetall).
The sandwich arrangement was cured within 25 minutes under a W-Himmel manufactured by Torgauer Machinenbau GmbH by irradiation with blacklight tubes of the type TL-D 36W/08 manufactured by Philips, the W radiant power on the surface of the front glass amounting to 2 0 W/m2 .
Example 16: Production of a sandwich arrangement consisting of display screen, edge seal from Example 3, casting resin from Example 5 and sheet of glass t The edge-sealing composition from Example 3 was applied peripherally onto a cleaned, grey-~tained front sheet of .
glass (transmission'~60%) in the form of a strand having a diameter of 3.3 mm in such a way that an opening with a width of approximately 50 mm for filling with casting resin remained between the start and the end of the strand. Subsequently the front sheet of glass was placed on a cleaned flat display screen (32 inch, 16:9 format) and was pressed to such an extent by loading with 50 kg that a gap of about 0.5 mm was obtained in the centre of the arrangement between the front glass and the surface of the flat display screen.
The casting resin from Example 5 was poured via the edge opening itno this composite at an angle of about 30° by means of a PE tube via the edge opening. as far as just below the charging opening, and the edge opening was sealed with an ethylene/vinyl-acetate hot-melt adhesive (Heii3schmelzkleber 21 manufactured by Chemetall).
The sandwich arrangement was cured within 30 minutes under a W-Himmel manufactured by Torgauer Machinenbau GmbH by irradiation with blacklight tubes of the type TL-D 36W/08 manufactured by Philips, the UV radiant power on the surface of the front glass amounting to 25 W/m2.
Example 17: Production of a sandwich arrangement consisting of display screen, edge seal, casting resin from Example 6 and sheet of glass A permanently flexible edge-sealing compound based on isobutylene polymer (Naftotherm BU-TPS manufactured by Chemetall) was applied peripherally in the form of a round filament extruded to a diameter of 4.6 mm onto a cleaned 32-inch flat display screen in 16:9 format in . 20 such a way that a gap of about 50 min remained between the two ends of the filament as charging opening far the casting resin. Subsequently, a cleaned, grey-stained front sheet of glass {transmission 60 %) was placed in position and was pressed to such an extent by loading with 60 kg that a gap of about 1 mm was obtained in the centre between the front glass and the surface of the flat display screen.
The casting resin from Example 6 was poured into this composite via the edge opening at an angle of about 45°
by means of a PE tube via the edge opening as far as just below the charging opening, and the edge opening was sealed with an.ethylene/vinyl-acetate hat-melt adhesive (Heii3schmelzkleber 21 manufactured by Chemetall).

The sandwich arrangement was cured within 25 minutes under a W-Himmel manufactured by Torgauer Machinenbau GmbH by UV-irradiation with blacklight tubes of the type TL-D 36W/08 manufactured by Philips, the W radiant 5 power on the surface of the front glass amounting to 2 0 W/m2 .

Claims (9)

Claims

1. Use of a transparent casting resin, consisting of reactive acrylate and methacrylate monomers, acrylate and methacrylate oligomers, coupling agents and initiators, and of an edge seal for the purpose of producing a sandwich arrangement that consists of a display screen, a layer of casting resin, an edge seal laterally surrounding the layer of casting resin and a sheet of glass.

2. Use according to Claim 1, characterised in that the casting resin contains the following constituents (figures in percentage by weight, sum of the stated constituents = 100 %):
a) reactive acrylate and methacrylate 50 - 97 monomers b) acrylate-functional and methacrylate- 1 . - 40 functional oligomers c) non-reactive acrylate and methacrylate 0 - 15 homopolymers and copolymers d) fillers 0 - 5 e) plasticisers 0 - 15 f) coupling agents 0.3 - 3 g) photoinitiators 0.01 - 3 h) tackifying additives 0 - 5 i) stabilisers 0 - 2

3. Use according to Claim 2, characterised in that the casting resin contains the following constituents (figures in percentage by weight, sum of the stated constituents = 100 %):

a) reactive acrylate and methacrylate 80~- 97 monomers b) acrylate-functional and methacrylate- 1 ~- 20 functional oligomers c) non-reactive acrylate and methacrylate 0~- 15 homopolymers and copolymers d) fillers 0~- 5 e) plasticisers 0~- 15 f) coupling agents 0.3 - 3 g) photoinitiators 0.05 - 2 h) tackifying additives 0~ - 5 i) stabilisers 0 - 2 4. Use according to one of Claims 1 to 3, characterised in that the edge seal consists of a permanently flexible composition which has thermoplastic properties and which, after being fused, is applied in the form of a bead or strand onto the front of the display screen or onto the sheet of glass.

5. Use according to Claim 4, characterised in that the edge-sealing composition contains the following constituents (figures in percentage by weight, sum of the stated constituents = 100 %):
a) base polymer 30 - 100 b) thermoplastic polymers 0 - 50 c) natural and synthetic rubbers 0 - 50 d) tackifying additives 0 - 30 e) plasticisers 0 - 50 f) coupling agents 0 - 5 g) stabilisers 0 - 5 h) reinforcing and non-reinforcing 0 - 70 fillers with the base polymer consisting of a homopolymer, copolymer or terpolymer of isobutylene or a mixture thereof or of a homopolymer and/or copolymer of acrylates and/or methacrylates or mixtures thereof.

6. Use according to Claim 4, characterised in that the edge-sealing composition contains the following constituents (figures in percentage by weight, sum of the stated constituents = 100 %):

a) base polymer 40 - 100 b) thermoplastic polymers 0 - 30 c) natural and synthetic rubbers 0 - 30 d) tackifying resins 0 - 25 e) plasticisers 0 - 30 f) coupling agents 0 - 3 g) stabilisers 0 - 3 h) reinforcing and non-reinforcing 0 - 60 fillers 7. Use according to one of Claims 4 to 6, characterised in that the yield-point of the edge seal amounts to a maximum of 4000 Pa at 120 °C
(measured with a rheometer having plate/plate geometry, measuring-plate diameter 25 cm, measurement in oscillation at oscillation frequency 1 Hz, torque range from 0.1 mNm to 100 mNm, rate of shear from 10 -4 s-1 to 1 s-1).

8. Use according to Claim 7, characterised in that the yield-point of the edge seal amounts to a maximum of 2000 Pa at 120 °C.

9. Use according to one of Claims 1 to 8, characterised in that the production of the sandwich arrangement consists of the following process steps:

1. cleaning and drying of the display screen and of the sheet of glass 2. application of an edge seal onto the front of the display screen or onto the sheet of glass 3, congruent placement of the sheet of glass onto the front of the display screen

4. pressing of the composite obtained, consisting of display screen and sheet of glass, to the desired distance between display screen and sheet of glass

5. charging of the casting resin

6. de-aeration of the interspace and charging opening sealing

7. inspection of the interspace filled with casting resin for freedom from air bubbles

8. curing of the casting resin by irradiation with UV light

9. final inspection of the finished sandwich arrangement