EP1525282A1

EP1525282A1 - Fusible adhesives which can be cross-linked by radiation

Info

Publication number: EP1525282A1
Application number: EP03766249A
Authority: EP
Inventors: Thomas Möller; Andreas Ferencz; Marcus Heemann
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 2002-07-27
Filing date: 2003-07-22
Publication date: 2005-04-27
Also published as: WO2004013244A1; AU2003250129A1; BR0311887A; US20050165164A1; US7156944B2; DE10234369A1; CA2493312A1; AU2003250129B2

Abstract

According to the invention, in order to prepare an adhesive having both a high initial adhesive capacity and high heat resistance, a fusible adhesive which can be cross-linked by radiation and has a low tendency to creep is provided, said adhesive containing: between 0 and 40 wt. % of at least one natural or synthetic elastomer which cannot be cross-linked by radiation, as constituent (A); between 15 and 40 wt. % of at least one compound containing at least two olefinic double bonds, as constituent (B); and between 20 and 85 wt. % of a tackifying resin, as constituent (C). The inventive fusible adhesive is especially suitable for using on high-speed labelling machines, does not pull any threads, and is characterised not only by high heat resistance but also by a good adhesive capacity in relation to plastics and metals.

Description

H 05160 "Radiation-crosslinkable hotmelt pressure-sensitive adhesives"

The invention relates to radiation-crosslinkable hotmelt pressure-sensitive adhesives and their production and use.

Hotmelts are generally understood to be solid to wax-like and water- and solvent-free adhesives at room temperature, which are applied to the parts to be bonded from the melt and, after being joined, set physically when they cool down and solidify. The hotmelt pressure sensitive adhesives (HMPSA), which belong to the group of hot melt adhesives, remain permanently sticky and tacky when cooled and adhere immediately to almost all substrates with a slight pressure.

Hot melt pressure sensitive adhesives are widely used in industry and are used, for example, in the beverage industry for labeling, in the packaging industry, in the graphics industry, for example bookbinding, or for the production of disposable articles, for example toilet paper or baby diapers.

The main advantage of hotmelt PSAs is that they allow solvent-free application technology. This eliminates the need for costly intermediate drying stages. Since solvent-based adhesive systems have to meet ever increasing environmental requirements, hotmelt PSAs also offer ecological advantages.

Typical hotmelt PSAs are made up of base polymers, tackifying resins, optionally plasticizer oils and various additives. Commonly used base polymers are styrene copolymers, for example styrene-isoprene-styrene (SIS) -, styrene-butadiene-styrene (SBS) -, styrene Ethylene-butylene-styrene (SEBS) -, block copolymers; Ethylene vinyl acetate (EVA) - polymers or amorphous poly-α-olefins (APAO).

Hot melt pressure sensitive adhesives based on, for example, styrene-isoprene-styrene block copolymers can, as described in EP 0451920 B1, be crosslinked with UV light in the presence of (optionally polymerized) photoinitiators or by means of electron beams.

Hot melt pressure sensitive adhesives based on polyacrylates are also known. For example, WO 02/10307 describes PSAs based on block copolymers of the general type P (B) -P (A / C) -P (B), each block copolymer consisting of a middle copolymer block P (A / C), for example of copolymers of acrylates and isoprene and two end polymer blocks P (B), for example of styrene. The polymer P (A / C) has a glass transition temperature of 0 ° C. to -80 ° C., component C having at least one functional group which is inert in a radical polymerization reaction and P (B) being a polymer made from the monomer B represents, wherein the polymer P (B) has a glass transition temperature of 20 ° C to 175 ° C and wherein the polymer block P (B) is insoluble in the copolymer block P (A / C) and the blocks P (B) and P (A / C) are not miscible. Such PSAs are used to produce adhesive tapes.

To provide a pressure-sensitive adhesive with good adhesion at high temperatures, DE 694 18 829 T2 discloses a radiation-curable composition comprising a

(A) polyurethane oligomer which is capped with a radiation-reactive acrylic or methacrylic end group and a radiation-unreactive monool or polyol end group and

(B) a mercapto compound having no more than one SH group in an amount of about 0.1 to 2.0% by weight of the polyurethane oligomer.

The curable composition is then coated on a desired substrate, such as silicone masking paper, fabric, or film, and then the coated substrate is exposed to electron or ultraviolet radiation at a wavelength of 1,800 to 4,000 A for a sufficient period of time to start the polymerization and complete. The disadvantage here is that liquid adhesives (oligomers) are used which have a very low initial tack.

WO 00/27942 describes a process for producing a radiation-crosslinkable hotmelt adhesive which essentially consists of a depolymerized elastomer of relatively low molecular weight, a

Relatively high molecular weight elastomer, composed of a tackifying resin and a plasticizer. This

Hot melt adhesive is preferred for coating self-adhesive labels. After crosslinking by UV or electron beams, it is characterized by good adhesive properties at low temperatures up to room temperature.

A disadvantage of using depolymerized polymers is that

Depolymerization reactions to products with strongly fluctuating

Quality control data can lead and thus the production of specification-compliant adhesive formulations is difficult.

WO 00/22062 describes radiation-crosslinkable adhesives containing

Block copolymers with at least one butadiene block in which the 1,2-

Vinyl content is at least 25% by weight, as well as partially hydrogenated resin and partially or completely saturated oil.

In particular, they are styrene block copolymers which are anionic

Polymerization can be prepared with the incorporation of a multivalent coupling compound.

The adhesive compositions are characterized by a low viscosity, but low heat stability in the melt is to be expected for applications at temperatures of more than 160 ° C.

Based on this prior art, there was the task of hot melt pressure sensitive adhesives with improved processing and

To provide usage properties that have a low viscosity combined with high initial adhesion and high heat resistance of the bond. Good adhesion, especially to plastic surfaces, should be ensured. Additional, for processing the Hot melt adhesives important properties should be improved if possible, or at least maintained.

In particular, the hotmelt PSAs are said to run at high speed

Labeling machines can be used and ensure trouble-free machine operation.

The solution to this problem according to the invention can be found in the patent claims. It essentially consists of a radiation-crosslinkable hotmelt PSA with a low tendency to creep, containing 0 to 40% by weight of at least one natural or synthetic, non-radiation-crosslinkable elastomer as component (A), 15 to 40% by weight of at least one compound which has at least two olefinic compounds Contains double bonds as a component

(B) and 20 to 85% by weight of a tackifying resin as component (C).

Elastomers are polymers with rubber-elastic behavior, which can be repeatedly stretched at least twice their length at 20 ° C and immediately take on their initial dimensions again after removing the constraint required for the stretching. Elastomers generally have a glass transition temperature T _g below 0 ° C. In the context of the invention, component (A) from the group of the elastomers is acrylate, polyester-urethane, ethylene-acrylate, butyl rubber; Natural rubber; Ethylene-propylene copolymers; Ethylene-vinyl acetate copolymers or styrene copolymers are preferred, individually or in a mixture, the copolymers being random, alternating, graft or block copolymers. According to the invention, elastomer alloys, in particular EPDM / PP, NR / PP, EVA PVDC and NBR / PP as well as polyurethanes, polyether esters and polyether amides are also used. In particular, thermoplastic elastomers are preferred from the group of elastomers. Thermoplastic elastomers (TPE) per se are known in the prior art. This is understood to mean polymers, also called thermoplastic rubbers, which ideally are a combination of Have usage properties of elastomers and the processing properties of thermoplastics. This can be achieved if, in the corresponding polymers, there are at the same time soft and elastic segments with high ductility and low glass transition temperature as well as hard crystallizable segments with low ductility, high glass transition temperature and tendency to form associations. Characteristic for thermoplastic elastomers are thermolabile reversible cleavable crosslinking sites, mostly of a physical, but also of a chemical nature. According to the invention, the component (A) is the thermoplastic elastomers, in particular selected from the group of styrene block polymers, for example styrene and styrene-diene copolymers ( SBS, SIS, SBR), styrene-ethylene / butylene copolymers (SEBS) or styrene-ethylene / propylene-styrene copolymers (SEPS). SEBS polymers are available, for example, from Shell Chemical Company under the name "Kraton ^® ", SEPS polymers are available from Kuraray Company in Japan under the name "Septon ^® ". SIS polymers are manufactured by Dexco Polymer Corp. under the name "Vector" or from Enichem Elastomers under the name "Europren".

Component (B) in the radiation-crosslinkable hotmelt pressure-sensitive adhesive according to the invention contains 15 to 40% by weight, preferably 20 to 35% by weight, of at least one compound which contains at least two olefinic double bonds as component (B). The olefinic double bonds are preferably vinyl double bonds.

The main and / or side chain of component (B) can optionally contain alkyl, alkoxyl groups or halogen atoms, in particular chlorine or bromine.

Component (B) preferably contains at least one diolefin homo- or copolymer (B1) in the radiation-crosslinkable hotmelt pressure-sensitive adhesive according to the invention, the proportion of repeating diolefin units in component (B1) being 50 to 100% by weight, preferably 60 to 90 % By weight, and Component (B1) has olefinic double bonds along the main chain.

“Diolefins” are understood to mean unsaturated aliphatic and cycloaliphatic hydrocarbons which contain two double bonds in the molecule, that is to say alkadienes and cyclodienes. The diolefins preferably contain conjugated double bonds.

“Repeat unit” is understood to mean the smallest constitutional unit of a polymer chain.

In the context of the invention, homo- or copolymers of 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 1,3-pentadiene, 2-ethyl-1,3-butadiene are preferred as component (B1) , 2-propyl-1, 3-butadiene, 2-isopropyl-1, 3-butadiene, 2-hexyl-1, 3-butadiene, 2,3-dimethyl-1, 3-butadiene, 2,3-diethyl-1 , 3-butadiene, 2-methyl-1, 3-pentadiene, 2-methyl-1, 3-hexadiene, 2-methyl-1, 3-octadiens, 2-methyl-1, 3-decadiens, 2,3-dimethyl -1, 3-pentadiene, 2,3-dimethyl-1,3-hexadiene, 2,3-dimethyl-1,3-octadiene and 2,3-dimethyl-1,3-decadiene, 2-methyl-1,3 -cyclopentadiene, 2-methyl-1,3-cyclohectadiene, 2,3-dimethyl-1,3-cyclopentadiene, 2,3-dimethyl-1,3-cyclohexadiene, 2-chloro-1,3-butadiene, 2,3 - Dichloro-1, 3-butadiene, 1-fluoro-1, 3-butadiene, 2-chloro-1, 3-pentadiene, 2-chloro-1, 3-cyclopentadiene and 2-chloro-1, 3-cyclohexadiene.

In particular, homo- or copolymers of isoprene are preferred as component (B1).

In a particularly preferred embodiment, component (B) is a

Diolefin homo- or copolymer (B2) used, the proportion of diolefin repeating units in component (B2) 50 to 100

% By weight, preferably 60 to 90% by weight,

Component (B2) in the side chains and along the main chain olefinic

Has double bonds and the proportion of vinyl double bonds 5 to 100%, preferably 20 to 95

% and particularly preferably 30 to 90%, based on the total number of olefinic double bonds in component (B2). In the context of the invention, homopolymers of 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 1,3-pentadiene and cyclopentadiene are preferably used as component (B2).

Polyisoprenes with a share of 6-7% of the 3,4-isoprene repeating unit are obtained, for example, by polymerizing isoprene in the presence of butyllithium.

Particular preference is given to using at least one homopolymer of 1,3-butadiene as component (B2) in which the proportion of vinyl double bonds in the polymer is 30 to 100%, preferably 50 to 95%.

Furthermore, an alternating, statistical, gradient or graft copolymer of poly (1,2-butadiene), poly (1,2-isoprene) or poly (3,4-isoprene) is preferably used as component (B2).

In a further preferred embodiment, a copolymer is used as component (B2), which is obtainable by reacting monomers from the group 1, 3-butadiene, 2-methyl-1, 3-butadiene, 1, 3-pentadiene and / or cyclopentadiene a) with monomers of the dienes mentioned with one another and / or b) with monomers from the group 2,3-dimethyl-1, 3-butadiene, 1, 4-pentadiene, 2,3-pentadiene and / or c) with at least one simple olefinically unsaturated monomers from the group consisting of ethylene, propylene, butylene, hexene, octene, acrylic esters, acrylonitrile, vinyl esters, vinyl nitrile, vinyl aromatic compounds, such as, for. B. styrene.

In a further embodiment, homo- and / or copolymers of monomers from the group 1,3-butadiene, 2-methyl-1, 3-butadiene, 1, 3-pentadiene and / or cyclopentadiene are used as component (B2), the at least one , preferably 2 to 3, functional groups, for example hydroxyl groups, amino groups, epoxy groups, isocyanate groups, carboxyl groups, Have carboxylic anhydride groups, mercapto groups, silane groups and / or hydrosilyl groups.

The functional groups are such that they react with other functional groups, preferably with the formation of covalent bonds. Mixtures of polymers with the features of component (B2) in which one component (B2) is hydroxy-functional and another component (B2) carries at least one functional group selected from the group of isocyanate groups, acid anhydride groups and epoxy groups are preferred.

In a further embodiment, as component (B1) or (B2) diolefin homopolymers and / or copolymers are used which are modified with at least one further radiation-crosslinkable functional group, e.g. an acrylate, methacrylate or epoxy group.

In mixtures of (B1) with (B2), (B1) is 1 to 35% by weight, preferably 5 to 35

% By weight and particularly preferably 10 to 30% by weight in the invention

Hot melt pressure sensitive adhesive composition included.

The molar mass of components (B1) and (B2) is between 500 to

100,000 g / mol, preferably 1,000 to 60,000 g / mol and particularly preferably 1

500 to 20,000 g / mol.

The viscosities of (B1) and (B2) each range from 60 mPa * s to 1

500 mPa ^* s at 20 ° C or in the range 500 mPa * s to 2,000 mPa * s at 100 ° C.

In a further embodiment of the invention, component (B) in the radiation-crosslinkable hotmelt pressure-sensitive adhesive according to the invention comprises at least one compound (B3) which is selected from the group consisting of unsaturated polyesters, polyethers or polyurethanes, polyacrylic and / or polymethacrylic acid alkyl esters, ( Meth) acrylic acid homopolymers and / or copolymers and / or vinyl polymers. Compounds that can be used for the invention are, for example, at CG. Roffey in "Photogeneration of Reactive Species for UV Curing", published by John Wiley & Sons, 1997 on pages 182 (vinyl derivatives), 482-485 (unsaturated polyesters), 487-502 (polyester, polyether, epoxy, Polyurethane and melamine acrylates), 504-508 (radiation-crosslinkable Organopolysiloxane polymers) and R. Holmann and P. Oldring in “UN. and EB Curing Formulation for Printing Inks, Coatings and Paints ", published by SIFA (Selective Industrial Training Associates Limited, London, UK), 2nd edition, 1988, pages 23-26 (epoxy-acrylates), 27-35 (urethane -Acrylate), 36-39 (polyester-acrylate), 39-41 (polyether-acrylate), 41 (vinyl polymer), 42-43 (unsaturated polyester).

Comonomers of (meth) acrylic acid which contain styrene, methylstyrene and / or other alkylstyrenes and alpha-olefins as comonomers are preferred as component (B3).

Di- and / or higher-functional acrylate or methacrylate esters are particularly suitable as component (B3). Such acrylate or methacrylate esters include, for example, esters of acrylic acid or methacrylic acid with aromatic, aliphatic or cycloaliphatic polyols or acrylate esters of polyether alcohols. Suitable compounds are at CG. Roffey "Photogeneration of Reactive Species for UV Curing" on pages 537-560 and R. Holman and P. Oldring "UN. And E.B. Curing Formulation for Printing Inks, Coatings and Paints" on pages 52-59.

Acrylate esters of aliphatic polyols with 2 to about 40 carbon atoms include, for example, Νeopentylglycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, and

(Meth) acrylate esters of sorbitol and other sugar alcohols. These (meth) acrylate esters of aliphatic or cycloaliphatic diols can be modified with an aliphatic ester or an alkylene oxide. The aliphatic ester modified acrylates include, for example

Neopentylglycol hydroxypivalate di (meth) acrylate, caprolactone modified

Neopentyl glycol hydroxypivalate di (meth) acrylates and the like. The alkyl oxide-modified acrylate compounds include, for example, ethylene oxide-modified neopentyl glycol di (meth) acrylates and propylene oxide-modified

Neopentyl glycol di (meth) acrylates, ethylene oxide modified 1, 6-

Hexanediol di (meth) acrylates or propylene oxide-modified 1,6-

Hexanediol di (meth) acrylates or mixtures of two or more thereof. Acrylates or methacrylates containing aromatic groups can also be used. These include corresponding bisphenol A compounds, for example diacrylates or dimethacrylates of adducts of bisphenol A with alkylene oxides, for example adducts of bisphenol A with ethylene oxide and / or propylene oxide. Acrylate monomers based on polyether polyols include, for example, neopentyl glycol-modified (meth) acrylates, trimethylolpropane di (meth) acrylates, polyethylene glycol di (meth) acrylates, polypropylene glycol di (meth) acrylates and the like. Trifunctional and higher functional acrylate monomers include, for example, trimethylolpropane tri (meth) acrylate, pentaerythritol tri- and tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerytrhitol penta (meth) acrylate,

Dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, pentaerythritol tetra (meth) acrylate,

Tris [(meth) acryloxyethyl] isocyanurate, caprolactone-modified

Tris [(meth) acryloxyethyl] isocyanurate or trimethylolpropane tetra (meth) acrylate or mixtures of two or more thereof.

Among the di-, tri- or higher-functional acrylate monomers mentioned which can be used as component B according to the invention are di-, tri- and tetrapropylene glycol diacrylate, neopentylglycol propoxylate di (meth) acrylate,

Trimethylolpropane tri (meth) acrylate, trimethylolpropane monethoxytri (meth) acrylate and pentaerythritol triacrylate are preferred.

(Meth) acrylate esters based on polyols containing urethane groups can be prepared by reacting a polyol with a di- or higher-functional isocyanate, so that OH-terminated polyurethane prepolymers are formed which are esterified with (meth) acrylic acid to give the corresponding diesters.

Component (B3) is contained in the radiation-crosslinkable hotmelt PSA according to the invention in an amount of 0 to 40% by weight, preferably 5 to 35% by weight, particularly preferably 10 to 30% by weight. If, in mixtures of (B2) with (B3) in component (B2), the proportion of vinyl double bonds is 5 to 30%, based on the total number of olefinic double bonds in component (B2), component (B3) is 10 to 35% by weight .-%, preferably 15 to 30 wt .-%, contained in the hot melt pressure sensitive adhesive. In a further embodiment of the invention, the radiation-crosslinkable hotmelt pressure-sensitive adhesive according to the invention contains at least one compound (L) which is selected from the group of the elastomers (A), these elastomers being modified with at least two radiation-crosslinkable functional groups, for example with acrylate or methacrylate - or epoxy groups.

The hotmelt PSA according to the invention contains at least one tackifying resin as component (C).

The resin creates an additional stickiness and improves the compatibility of the hot melt pressure sensitive adhesive components. It is used in an amount of 20 to 85% by weight, preferably 30 to 70% by weight, particularly preferably 35 to 65% by weight. These are, in particular, resins which have a softening point of 90 to 120 ° C. (ring-ball method). These are aromatic, aliphatic or cycloaliphatic hydrocarbon resins, and modified or hydrogenated versions thereof. Specific examples are: aliphatic or alicyclic petroleum hydrocarbon resins and hydrogenated derivatives thereof. Further resins which can be used in the context of the invention are:

a) Hydroabietyl alcohol and its esters, especially its esters with aromatic carboxylic acids such as terephthalic acid and phthalic acid, b) preferably modified natural resins such as resin acids from balsamic resin, tall resin or root resin, for example fully saponified balsamic resin or alkyl esters of optionally partially hydrogenated rosin with low softening points such as methyl and diethylene glycol -, glycerol and pentaerythritol esters, c) terpene resins, in particular terpolymers or copolymers of terpene. Examples are: styrene terpenes, alpha-methyl styrene terpenes, phenol-modified terpene resins and hydrogenated derivatives thereof; d) acrylic acid copolymers, preferably styrene-acrylic acid copolymers and e) resins based on functional hydrocarbon resins. It is also possible to use an alkyl ester of partially hydrogenated rosin as the tackifying resin, the alkyl group preferably containing 1 to 6 carbon atoms.

It is preferred to use partially polymerized tall resin, hydrogenated hydrocarbon resin and rosin glycerol ester.

In the context of the present invention, the feature “radiation-crosslinkable” is understood to mean the initiation of a polymerization reaction under the influence of radiation (photopolymerization). Radiation is to be understood here to mean any type of radiation which causes irreversible crosslinking in the crosslinkable hotmelt adhesive layer to be irradiated. Particularly suitable are UV, electron beams, short-wave visible light, but also IR radiation, with ESH or UV radiation the desired product properties are set via the radiation dose, with IR radiation via the product temperature and the dwell time.

An overview of the prior art for radiation crosslinking of hotmelt PSAs can be found, for example, by R. Jordan, “Hotmelt PSAs”, volume 6b from the “Adhesive Monographs” series by Hinderwaldner-Verlag, 1989, pages 126 to 155 or in the article “UV - Crosslinkable acrylate hotmelt adhesives "by Auchter, Barwich, Rehmer and Jäger in" kleben & dichten "37 (1993), pages 14 to 20.

Radiation crosslinking by UV or electron beams is preferred in the context of this invention.

The hotmelt PSA of the invention is irradiated with UV light at a wavelength in the range from 100 nm to 380 nm. The UV rays are generally generated in gas discharge lamps, of which mercury vapor lamps in particular can be used as medium and high pressure lamps (1 to 10 bar). 50 - 2000 J / cm ² should be used as the UV radiation dose.

When the hotmelt PSA according to the invention is irradiated with electron beams, a radiation dose of 10 to 100 kilogray (kGy) is preferred. When the hotmelt PSA according to the invention is irradiated with UV light, the crosslinking is controlled in addition to the specific radiation dose by the use of photoinitiators, photosensitizers or regulator molecules:

Component (D) contains 0 to 10% by weight of at least one photoinitiator, photosensitizer and / or regulator molecule in the radiation-crosslinkable hotmelt pressure-sensitive adhesive. In the case of irradiation with UV light, at least one photoinitiator in the order of 0.1% by weight to 10% by weight, preferably 0.2% by weight to 5% by weight, is contained in the adhesive according to the invention , In the context of the present invention, all commercially available photoinitiators which are compatible with the hotmelt pressure-sensitive adhesive according to the invention are basically suitable, ie. H. result in at least largely homogeneous mixtures. The photoinitiators are substances or mixtures of substances which are stable under the exclusion of light and which absorb so much energy when exposed to radiation that they trigger free-radical or ionic polymerizations. Radical polymerizations are triggered, for example, by the decomposition of peroxides, disulfides, benzoin derivatives and certain aliphatic ketones. Radically active photoinitiators which can be used for the invention are available from S.P. Pappas, in "UV Curing: Science and Technology" Technology Marketing Corporation, 1978, on pages 2-20. Photoinitiators from the following group are preferred: benzoin and its derivatives as well as phenylhydroxyalkanone types and thioxanthone types. Ketone-based photoinitiators R.Holman and P. Oldring describe "UN. and EB Curing Formulation for Printing Inks, Coatings and Paints" on pages 75-77. In particular, benzophenone, 2,4,6-

Trimethylbenzophenone, 4-methylbenzophenone or mixtures of alkyl benzophenone, e.g. B. Esacure TZT, camphorquinone, quantacure (manufacturer: International Bio-Synthetics), Kayacure MBP (manufacturer Νippon Kayaku), Esacure BO (manufacturer: Fratelli Lamberti), Trigonal 14 (manufacturer: Akzo), photoinitiators of Irgacure ^® -, Darocure ^® - or Speedcure ^® series (manufacturer: Ciba-Geigy), Darocure ^® 1173 and / or Fi-4 (manufacturer: Eastman) Irgacure ^® 651, Irgacure ^® 369, Irgacure ^® 184, Irgacure ^® 907, Irgacure ^® are particularly suitable 1850 Irgacure ^® 1173 (Darocur ^® 1173), Irgacure ^® 1116, Speedcure ^® EDB, Speedcure ^® ITX, Irgacure ^® 784 or Irgacure ^® 2959 or mixtures of two or more thereof.

In the case of cationic photopolymerization, the photoinitiators are subjected to molecular cleavage under the influence of UV radiation with simultaneous formation of free Lewis or Brönsted acids. Preferred cationic photoinitiators are, for example, the aryldiazonium salts known to the person skilled in the art, for example diaryliodonium or triarylsulfonium salts. The use of iodonium salts as photoinitiators in cationically polymerizable compositions is described in JN.Crivello, "Photoinitiated Cationic Polymerization" in: UV Curing: Science and Technology, Editor SP Pappas, pages 24 to 71, Technology Marketing Cooperation, Νorwalk Conn. 1980, isbn. 0-686-23773-0 or the application DE 163066 A1, which cationic photoinitiators can be used with preference in the case of pappas in the volume cited above from Table VI, pages 44-45.

In a preferred embodiment, a photoinitiator which has a molecular weight of more than about 150 is used at least in part. Commercially available photoinitiators which meet this requirement are, for example, Darocur ^® 1173, Esacure ^® KIP 150 or Irgacure ^® 369th

From the group of polymeric photoinitiators, polymeric cinnamic acid esters, for example polyvinyl cinnamate, are preferred. When irradiated with UV light, cinnamates form Truximate or Truxillate as dimerization products. The mode of action and examples of usable cinnamates and the likewise usable alkyl, aryl or acyl azides are described in C. Roffey "Photogeneration of Reactive Species for UV Curing" on pages 192-194 and in P. Pappas "UV Curing: Science and Technology "on pages 234-243.

It is also possible to provide the photoinitiator with a functional group which can be polymerized by irradiation with UV light or with electron beams, the functional group which can be polymerized with UV light or with electron beams being connected to the photoinitiator, for example, by reacting the photoinitiator with an unsaturated carboxylic acid can be. As unsaturated carboxylic acid are suitable for example acrylic acid or methacrylic acid. The reaction products of Irgacure® 2959 with acrylic acid or methacrylic acid are particularly suitable in the context of the present invention. It is therefore possible that a compound is used as the photoinitiator which has both a photoinitiator and a functional group which can be polymerized by irradiation with UV light or with electron beams.

Furthermore, co-initiators, for example amines such as Photomer ^® 4127 F or Uvecryl ^® 7100 or photosensitizers can be used. The use of photosensitizers makes it possible to shorten the absorption waves of photopolymerization initiators and / or to extend them to longer wavelengths and in this way to accelerate the crosslinking rate. The radiation of a certain wavelength they absorb is transferred as energy to the photopolymerization initiator. Photosensitizers which are preferably used in the context of the invention are, for example, acetophenone, benzophenone and fluorescein and their derivatives.

In a particularly advantageous embodiment, the hotmelt pressure-sensitive adhesive according to the invention contains 0 to 15% by weight, preferably 5 to 12% by weight, at least one compound from the group of the difunctional or higher-functional mercaptans and / or thio compounds as component (E). Component (E) reacts in a so-called “thiol-ene” reaction with component (A) and / or (B1) and / or (B2) and / or (B3).

Thiol-ene reactions have long been known and are described, for example, by Oswald in “Die Makromolekulare Chemie”, 97, 258-266 (1966) and by R. Holman and P. Oldring “UV and EB Curing Formulation for Printing Inks, Coatings and Paints "on page 44, by CG. Roffey "Photogeneration of Reactive Species for UV Curing" on page 514-517 and by P. Pappas "UV Curing: Science and Technology" on page 245-246. To carry out the thiol-ene reaction, polythiols and polyenes are generally mixed with one another and crosslink free-radically to form polythiol ethers. Acid-catalyzed crosslinking is also known from the literature. The polythiols contain at least two thiol groups. However, polythiols with three or four thiol groups, such as pentaerythritol tetrakis (betamercaptopropionate), can also be used.

To introduce the thiol groups, one can advantageously start from existing hydroxyl groups, which are esterified, for example, with thioglycolic acid. In this way, e.g. Esterify pentaerythritol with thioglycolic acid to give pentaerythritol tetrathioglycolate. Cyclic polyols such as e.g. Esterify sugar alcohols. Specific compounds which are suitable for the purposes of the invention are, for example, pentaerythritol-tetrathioglykolat, pentaerythritol tetramercaptoacetat, Pentaerythritmercaptopropionat (PETMP), trimethylolpropane trithioglykolat, dithioglycol, Triglykoldithiol, Dipentadimercaptan, Ethylcyclohexyldimermercaptan, 1, 6-Hexandimercaptan,

Ethanedithiol dimethacrylate, propanedithiol dimethacrylate. Mercapto-terminated polysulfide resins can also be used. Alkylene oxide-modified polythiols are preferably used. Specific examples are ethoxylated and / or propoxylated polythiol based on trimethylolpropane and pentaerythritol. Other suitable connections are at CG. Roffey "Photogeneration of Reactive Species for UV Curing" on pages 514-517 and by R. Holman and P. Oldring "U.V. and E.B. Curing Formulation for Printing Inks, Coatings and Paints" on page 44.

To the required application properties, such. B. to achieve a certain cohesive strength, viscosity, softening point or setting speed, further additives may be necessary in the adhesive formulation. These include plasticizers to increase flexibility, stabilizers, antioxidants to reduce the oxidative change during processing of the melt under the influence of oxygen and to improve the aging behavior of the glued joint. Fillers can also be used to increase strength and, if necessary, reduce costs.

The plasticizer, component (F), is preferably used to adjust the viscosity and is in the hotmelt PSA according to the invention generally in a concentration of 0 to 30% by weight, preferably in a concentration of 5 to 25% by weight.

Usable plasticizers are medical white oils, naphthenic mineral oils, phthalates, adipates, polypropylene, polybutene, polyisoprene oligomers, hydrogenated polyisoprene and / or polybutadiene oligomers, benzoate esters, vegetable or animal oils and their derivatives.

Hydrogenated plasticizers are selected from the group of the paraffinic hydrocarbon oils - for example commercially available under the trade name Primol® from Exxon - the polyisobutylene, poly-1-butene oils or the hydrogenated naphthenic oils. The polyisobutylenes preferably have an average molecular weight of 600 to 5000, preferably 800 to 4000. Typically, these are highly viscous liquids at room temperature. Usable polyisobutylenes are available under the name "Parapol" from Exxon Chemicals or under the name "Oppanol" from BASF. Preferred paraffin oils used have a viscosity of 100 to 600 mPas, preferably 150 to 300 mPas at 25 ° C. They are available as "Kaydol" from Witco or Primol 352 from Esso. Mono- or polyhydric alcohols, preferably glycol monophenyl ether, hexamethylene glycol, glycerol and in particular polyalkylene glycols with a molecular weight of 200 to 6000 can also be used. Polyethylene glycols with a molecular weight of up to approximately are preferred 1,000, preferably up to about 600.

Polypropylene glycol and polybutylene glycol as well as polymethylene glycol can also be used.

Conveniently, esters are used as plasticizers, e.g. B. liquid polyesters and glycerol esters such as glycerol diacetate and glycerol triacetate, and neopentyl glycol dibenzoate, glyceryl tribenzoate, pentaerythritol tetrabenzoate and 1,4-cyclohexanedimethanol dibenzoate. Finally, alkyl monoamines and fatty acids with preferably 8 to 36 carbon atoms may also be useful. Plasticizers based on aromatic dicarboxylic acid esters, ie the corresponding ester of phthalic acid, isophthalic acid or terephthalic acid, are preferably used. The alcohol residue in these esters used as plasticizers usually has 1 to 8 carbon atoms. Alkyl monoamines and fatty acids are also suitable as plasticizers; alkyl monoamines and fatty acids with 8 to 36 carbon atoms are preferred.

Optionally, waxes can be added to the hotmelt PSA as component (G) in amounts of 0 to 30% by weight. The amount is dimensioned such that on the one hand the viscosity is reduced to the desired range, but on the other hand the adhesion is not adversely affected. The wax can be of natural, chemically modified or synthetic origin. Vegetable waxes, animal waxes, mineral waxes or petrochemical waxes can be used as natural waxes. Hard waxes such as montan ester waxes, Sarsol waxes, etc. can be used as chemically modified waxes. Polyalkylene waxes and polyethylene glycol waxes are used as synthetic waxes. Petrochemical waxes such as petrolatum, paraffin waxes, micro waxes and synthetic waxes, in particular polyethylene waxes with melting points between 85 and 140 ° C. and molecular weights in the range from 500 to 3,500, paraffin waxes with melting points in the range from 45 to 70 ° C. and molecular weights between 225 and 500, microcrystalline waxes with melting points in the range from 60 to 95 ° C and synthetic Fischer-Tropsch waxes with melting points in the range from 100 to 115 ° C are used.

In addition, customary auxiliaries and additives, component (H), can be added to the hotmelt PSA according to the invention. The stabilizers should be mentioned here first. Their task is to prevent the reactive monomers from reacting undesirably or prematurely and to protect the polymers from decomposition during processing. The antioxidants are particularly worth mentioning here. They are usually added to the hotmelt PSA in amounts of up to 3% by weight, preferably in amounts of about 0.1 to 1.0% by weight.

Stabilizers which can be used as additives in the context of the invention, in particular UV stabilizers, initiators or antioxidants, include phosphites, phenols, sterically hindered phenols of high molecular weight (M _n ), polyfunctional phenols, sulfur- and phosphorus-containing phenols or amines. As part of the Phenols which can be used as additives are, for example, hydroquinone, hydroquinone methyl ether 2,3- (di-tert-butyl) hydroquinone, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl- 4-hydroxybenzyl) benzene; Pentaerythritol tetrakis 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate; n-octadecyl-3,5-di-tert-butyl-4-hydroxyphenyl) propionate; 4,4-methylenebis (2,6-di-tert-butyl-phenol); 4,4-thiobis (6-tert-butyl-o-cresol); 2,6-di-tert-butylphenol; 6- (4-hydroxyphenoxy) -2,4-bis (n-octylthio) -1, 3,5-triazine; Di-n-octadecyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate; 2- (n-octylthio) ethyl 3,5-di-tert-butyl-4-hydroxybenzoate; and sorbitol hexa [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]; and p-hydroxydiphenylamine or N, N'-diphenylenediamine or phenothiazine.

Additional additives can be included in the hot melt pressure sensitive adhesive in order to vary certain properties. These can include dyes such as titanium dioxide, fillers such as talc, clay and the like.

As component (I), the radiation-crosslinkable hotmelt pressure-sensitive adhesive according to the invention contains non-elastomeric polymers from the group consisting of ethylene-n-butyl acrylate copolymers, ethylene (meth) acrylic acid copolymers, amorphous polyolefins, for example polypropylene homopolymer, propylene-butene copolymers, propylene Hexene copolymers and in particular amorphous poly-alpha-olefins (APAO ^' s), which are produced by metallocene catalysis. However, preference is also given to using polyamides as component (I) which, if appropriate, give the hotmelt PSA additional flexibility, toughness and strength. It is also possible to add certain hydrophilic polymers as component (I), for example polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinyl methyl ether, polyethylene oxide, polyvinyl pyrrolidone, polyethyloxazoline or starch or cellulose esters, in particular the acetates with a degree of substitution of less than 2.5 which, for example, increase the wettability of the adhesives.

Component (I) is present in the hotmelt pressure-sensitive adhesive according to the invention in an amount of 0 to 20% by weight. In addition, the radiation-crosslinkable hotmelt PSA according to the invention can contain adhesion promoters as component (J). Adhesion promoters are substances that improve the adhesive strength of materials to be combined. In particular, adhesion promoters are said to improve the aging behavior of bonds to moist atmospheres. Typical adhesion promoters are, for example, ethylene / acrylamide comonomers, polymeric isocyanates, reactive organosilicon compounds or phosphorus derivatives. In the context of the invention, phosphorus derivatives are preferably used as adhesion promoters, as are disclosed in WO 99/64529 (page 7, line 14 to page 9, line 5), for example 2-methacryloyloyethyl phosphate, bis- (2-meth-acryloxyloxyethyl) ) phosphate, or mixtures thereof. Compounds containing carboxylic acid can also be used as adhesion promoters. Compounds of this type are disclosed, for example, in WO 01/16244 (page 7, line 7 to page 8, line 31) or in WO 00/29456 (page 11, line 15 to page 12, line 2). Commercially available products are available, for example, from UCB-Chemicals, B-1620 Drogenbos, Belgium under the product class "Ebecryl", for example Ebecryl 168 or Ebecryl 170.

Component (J) is 0 to 20 wt .-%, preferably 1 to 15 wt .-% contained in the adhesive.

For applications at temperatures above 160 "C, especially above 180 ° C

210 ° C, the hot melt pressure sensitive adhesive contains as component (K) polyphenylene oxide

(PPO). Polyphenylene oxide is described in US 5,910,526 and US 5,750,622 described and, for example, from the company. General Elecric Plastics under the name Noryl ^®

PPO 803, PPO 808, SA 120 or SA 407 offered.

The polyphenylene oxide used in the context of the invention preferably has one

Glass transition temperature (Tg) in the range of 150 to 210 ° C

PPO as component (K) is 0 to 20% by weight, preferably 1 to 10% by weight, in

Glue included. Appropriate formulation gives hot melt pressure sensitive adhesives which are characterized by high pressure sensitive tack. In the most ready embodiment of the invention, the hotmelt PSA contains: 0 to 40% by weight of at least one natural or synthetic, non-radiation-crosslinkable elastomer as component (A), 15 to 40% by weight of at least one compound which contains at least two olefinic double bonds, as component (B), 20 to 85% by weight of a tackifying resin as component (C), 0 to 10% by weight of at least one photoinitiator, photosensitizer and / or regulator molecule as component (D),

0 to 15% by weight of at least one compound from the group of the difunctional or higher functional mercaptans and / or thio compounds as component (E),

0 to 30% by weight of a plasticizer, as component (F), 0 to 30% by weight of a wax as component (G), 0 to 3% by weight of an auxiliary and additive as component (H), 0 up to 20 wt .-% of non-elastomeric polymers from the group of ethylene-n-butyl acrylate copolymers, ethylene (meth) acrylic acid copolymers, amorphous polyolefins, propylene-butene copolymers, propylene-hexene copolymers and amorphous poly-α-olefins which were produced by metallocene catalysis as component (I),

0 to 20% by weight of an adhesion promoter as component (J), 0 to 20% by weight of a polyphenylene oxide (PPO) as component (K), and

0 to 40% by weight of elastomers from the group of component (A), these elastomers being modified with at least two radiation-crosslinkable functional groups, e.g. with acrylate, methacrylate or epoxy groups, as component (L)

In a preferred embodiment, the invention contains

Hotmelt adhesive:

5 to 20% by weight of at least one elastomer from the group of the styrene

Copolymers, ethylene-vinyl acetate copolymers or mixtures of these

Copolymers as component (A), 0 to 35% by weight, preferably 1 to 30% by weight, of at least one butadiene homo- or copolymer with a 1,2-vinyl content of 30-90% as component (B2),

0 to 35% by weight, preferably 1 to 30% by weight, of at least one diacrylate oligomer as component (B3),

45 to 75% by weight of at least one tackifying resin from the group of the terpene hydrocarbons as component (C),

3 to 10% by weight of at least one photoinitiator as component (D)

0.1 to 1% by weight of at least one antioxidant as component (H),

0 to 20% by weight of a plasticizer as component (F), the sum of components (A) to (H) giving 100% by weight.

In a further preferred embodiment, the hotmelt PSA according to the invention contains

- 15 to 20 wt .-% of at least one styrene block polymer as a component

(A),

15 to 30% by weight of at least one butadiene homo- or copolymer with a 1,2-vinyl content of 30-90% as component (B2),

45 to 60% by weight of at least one tackifying resin from the group of the terpene hydrocarbons as component (C),

3 to 10% by weight of at least one photoinitiator as component (D),

0.1 to 1% by weight of at least one antioxidant as component (H),

5 to 12% by weight of at least one at least difunctional thio compound as component (E), the sum of components (A) to (E) giving 100% by weight.

5 to 20% by weight of at least one styrene block polymer as component (A),

15 to 35% by weight of a diacrylate oligomer as component (B3),

0.5 to 3% by weight of a photoinitiator as component (D), 0.1 to 1% by weight of at least one antioxidant as component (H),

10 to 20% by weight of a plasticizer based on a naphthenic mineral oil as component (F), the sum of components (A) to (H) giving 100% by weight.

The hot melt pressure sensitive adhesive according to the invention is generally produced by mixing. The optionally plasticizers (component (F)), optionally waxes and resins (components (G) and (C)) are premixed at 120 ° C. to 180 ° C., in particular at 160 ° C., to form a homogeneous melt. After the addition of any auxiliaries and additives (component (H)), optionally photoinitiator and / or photosensitizer (component (D)) and optionally crosslinking agent containing sulfur groups (component (E)), the compound containing at least two olefinic double bonds is ( Component (B)), possibly the adhesion promoter (component (J)) and finally possibly the elastomer (component (A) and / or component (L)) and possibly further non-elastomeric polymers (component (I)) and optionally polyphenylene oxide (component (K)) are added with stirring and stirred until homogeneous.

After filling the completely homogenized composition in suitable containers, it is allowed to cool, whereby it solidifies. The hotmelt pressure-sensitive adhesive according to the invention is generally of firm consistency at 20 ° C. and is largely free of solvents which would interfere with the application from the melt. Of course, the melt could also be applied directly to a substrate without cooling and thus used directly for gluing, without an intermediate cooling. Usually, however, the hotmelt PSA according to the invention, like other commercially available hotmelt PSAs, is melted before use and then applied to the substrate to be bonded.

The hotmelt PSAs according to the invention are used for bonding substrates such as glass, lacquered or unpainted paper or corresponding cardboards and, above all, plastics such as PET, PEN, PP, PVC, PS and PE. Containers or foils or foil composites can be produced from this. The hotmelt PSAs according to the invention are distinguished in particular by a very good adhesion to the aforementioned plastics.

The substrates to be bonded are in particular hollow bodies on the one hand and labels on the other hand.

Specific hollow bodies are e.g. Bottles, cans, barrels, sleeves or cartridges. They consist essentially of optionally plated or galvanized metal - for example tinplate or aluminum -, glass or thermoplastic materials such as polyethylene terephthalate, polycarbonate, polyethylene, polypropylene, polyvinyl chloride or polystyrene. A polar plastic, in particular a polyester, is preferred. Such hollow bodies are used in particular for mineral water and soft drinks.

The labels consist of thermoplastic materials such as polyethylene, polypropylene, polystyrene, polyvinyl chloride or cellophane. It is preferred to use labels made from a film based on non-polar plastics, in particular oriented polypropylene (OPP). Furthermore, the labels can also be based on paper, possibly in combination with a polymer. Depending on the material and manufacturing process, the following labels are suitable, for example: simple labels made from unfinished paper, labels made from refined paper, glossy labels made from cast-coated label papers, labels made from steamed paper and labels made from aluminum-coated paper.

There are no special requirements for the shape of the labels. For example, Wraparound labels, and label labels.

The hotmelt PSAs according to the invention are particularly suitable for labeling hollow bodies, in particular hollow plastic bodies, which are filled with liquids which contain substances capable of gas formation. For example, these can be PET bottles that contain carbonated beverages. These liquids and the substances contained therein which are capable of gas formation, here referred to collectively as an ingredient, have the property of bringing about changes in shape of the hollow bodies. Such changes in shape occur, for example, in the case of changes in volume of the ingredients located in the hollow body. The change in shape of the hollow body consists, for example, of an expansion, specifically when the ingredients are filled in or these ingredients are exposed to temperature increases. The change in shape of the hollow body often causes the adhesive seam to shift in the case of labels which are overlapped with commercially available hotmelt adhesives. This exposes a part of the adhesive layer to which, for example, dirt can adhere. In particular in the area of overlap bonding, the hotmelt PSA according to the invention has a very low tendency to creep after being irradiated with UV or electron beams, and at the same time has good adhesive strength in the overlap bonding. This results, if at all, in only very slight (tangential) displacements of the overlap-bonded labels when the shape of the hollow bodies enveloped by these overlap-bonded labels changes. Problems such as, for example, the contamination of the adhesive layer exposed by the shifting process are thus prevented.

In a further particular use, the hotmelt PSAs according to the invention are suitable for use in labeling aerosol cans or contour bottles with subsequent shrinking of the labels. In general, the shrinkable labels are shrunk onto the contour of the aerosol can at temperatures of at least 250 ° C. within a few seconds. Often there is a shift in the overlap bonding with pressure-sensitive adhesives bonded from the prior art when the heat treatment necessary for the shrinking process is carried out.

When the hotmelt PSAs according to the invention are used, the entrainment or overlap bonding is not released, nor is the overlap bonding shifted. For problem-free processing, the hotmelt PSAs according to the invention have a correspondingly low viscosity before irradiation, at 120 ° C. it is 100 mPa * s to 1500 mPa * s, preferably 180 mPa * s to 1100 mPa * s and particularly preferably 250 mPa * s to 700 mPa ^* s, measured according to Brookfield (ASTM D 3236-88).

For example, the hotmelt PSAs according to the invention have the required low viscosity at low processing temperatures, as used, for example, on temperature-sensitive labels, e.g. B. plastic labels (usually OPP) is desired. The processing temperatures are in the range from 70 ° C to 150 ° C, preferably in the range from 90 ° C to 140 ° C

The low viscosity also ensures that the machine runs cleanly on commercially available roll labeling machines (e.g. Kranes ContiRoll, KHS Carmichael, Sasib Rollquattro and others). Contamination, for example thread formation (so-called “angel hair”), is avoided in particular on machines at high speeds (over 30,000 hollow bodies / h).

The high pressure-sensitive adhesive ensures that the labels are carried safely on high-speed machines. Fast-running machines are understood in particular to be machines for labeling that have a processing capacity of 30,000 to 120,000 hollow bodies - i. d. R. Bottles - dispose per hour and per glue station.

Processing takes place on labeling machines that apply the hotmelt adhesive to the label or to the hollow body with segments (e.g. Kranes ContiRoll), rollers (e.g. Kranes Canmatic) or nozzles (e.g. Langguth E 62). As a rule, the adhesive is applied in such a way that there is a driving area (label on the hollow body) and an overlap area (label end at the beginning). The hotmelt PSA of the invention can be used both as a take-away and as an overlap adhesive. This simplifies the Labeling process, for example, this eliminates the need for a second melting tank.

But the use of two different hotmelt adhesives is also conceivable, e.g. to ensure detachment from the hollow body.

After the application of the hotmelt PSA according to the invention and the

Assembling the parts to be glued, for example label on hollow body and / or label on label), the hotmelt PSA according to the invention is irradiated with a suitable UV or electron beam dose. For example, suitable means that the hotmelt PSA has sufficient adhesion and bonds the substrates, but shows no or very limited creep.

Transparent labels are preferably used for the irradiation with UV rays.

The branching or crosslinking caused by the radiation becomes high

Final adhesion and heat resistance achieved, the following summary

Areas of application in the field of labeling are:

^■ Labeling of aerosol cans or contour bottles with subsequent shrinking of the labels. By using the hotmelt pressure-sensitive adhesives according to the invention, neither the entrainment nor the overlap bonding is released. The (slight) opening of the label corners frequently observed in this process is also avoided when using the hotmelt PSAs according to the invention. The hotmelt pressure-sensitive adhesives used according to the invention are characterized in particular in addition to the high heat resistance mentioned above, also by a relatively high cohesion and adhesion.

^■ Labeling with the achievement of properties of a ^{tamper-evident} closure. Labels or strips (control strips etc.) made of different materials such as OPP can only be opened with a tear due to the high level of adhesion. Such labels can be used, for example, in the area of security labeling, since when trying to remove the label used as a seal-like closure, there are clear traces in the surface to be removed that confirm the attempt to remove it.

^■ Labeling with high demands on the storage stability of the labeled goods. The storage of with the hotmelt PSAs according to the invention glued objects, in particular labeled hollow bodies at storage temperatures of 60 ° C or higher, is also possible over a long period of time. This applies, for example, to hot drinks that are offered in appropriate ovens and are intended for consumption on site.

^■ Labeling with subsequent pasteurization, for example, hot steam of hot melt pressure sensitive adhesives of the invention are possible through the use. Due to the high heat resistance of the bond, any heat build-up that may occur is not a problem.

■ Heat stress that occurs in the processing process (e.g. when shrink-fitting trays) can be easily and safely overcome without impairing the bond.

After irradiation with UV rays or electron beams, the hotmelt PSAs according to the invention have a low tendency to creep and, depending on the duration of the irradiation and requirements, can still be pressure-sensitive. The tackiness can be assessed qualitatively. When touching the adhesive layer, for example with the fingers, stickiness ("tack") can be determined. In the context of the invention, a low tendency to creep means that after a) application of the hotmelt pressure-sensitive adhesive according to the invention with a layer thickness of 50-100 g / m ² on a shrink film made of OPP with a thickness of 48-52 μm, b) irradiation with UV or electron beams, c) overlapping adhesive film on film, d) temperature control of the overlap adhesive over a period of 24 hours at 60 ° C prior to the displacement of the adhesive seam Tempering compared to after tempering, less than or equal to 5 mm, preferably less than or equal to 3 mm and particularly preferably less than or equal to 1 mm. The invention finds general use in disposable (hygienic) manufacture or in packaging, particularly in labeling, in closing cartons and in bookbinding.

The subject matter of the invention will be explained in more detail with the aid of the following examples.

EXAMPLES I. Starting Components a) Butadiene-styrene copolymer without BHT (Stereon 841) from Firestone b) Terpene-hydrocarbon resin modified (Sylvares ZT 105 LT) from Arizona Chemical c) Polybutadiene 70% 1.2 - polymer, stab. with 100 ppm BHT (Ricon 150) from Colorado Chemical d) 3,3'-thiodipropionic acid dilauryl ester (Irganox PS 800) from Ciba-Geigy e) 2-hydroxy-2-methylpropiophenone (Darocur 1173) from Ciba Geigy f ) Pentaerythritol-PO adduct-mercaptan-terminated trifunctional (Capcure 3-800) from Cognis Corporation g) Pentaerythritol tetrakis [3 (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], (Irganox 1010 D) from Ciba-Geigy h) Photomer 4127 F: neopentyl glycol propoxylate diacrylate from Cognis

Corporation i) Nyflex 222 B: naphthenic mineral oil from Nynas j) Esacure KIP 150: oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl)] phenyl] propanone from Lamberti k) Irgacure 369 : 2-benzyl-2-dimethylamino-1- (4-morpholino-phenyl) -butano-1 from Ciba Geigy I) Evatane HT 28-800: ethylene-vinyl acetate copolymer from Atofina m) Vector 4111 D: SIS block polymer from Exxon Mobil (Dexco). n) Vector 4461 D: styrene-butadiene-styrene block polymer from Exxon

Mobil o) Isolene 400: polyisoprene from Ter Hell & Co.GmbH

II. Production of hotmelt PSAs by mixing

The recipes are prepared by the generally customary method known to those skilled in the art by first mixing polymers (component (A) and (B)) and resins (component (C)) at 160 ° C. in a laboratory stirrer until they are mixed appear visually uniform (homogeneous). Then the other recipe ingredients are added and also completely homogenized. In general, about 60 to

120 minutes needed. Depending on the composition, the melt is transparent, opaque or cloudy (this also applies to the one cooled to room temperature

Melt).

The melt mixture is filled and then cooled, whereby it solidifies.

After cooling, it is - depending on the composition - for different

Purposes.

III. Recipe examples: Example 1:

Wording from:

175.0 g butadiene-styrene copolymer without BHT, CARN 9003-55-8 (Stereon 841 A)

595.0 g of terpene hydrocarbon resin modified, CARN 82347-62-4 (Sylvares

ZT 105 LT)

225.0 g polybutadiene 70% 1,2-polymer, stab. with 100ppm BHT, CARN 61789-96-

6 / 9003-17-2 (Ricon 150)

2.5 g pentaerythritol tetrakis [3 (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], CARN

6683-19-8 (Irganox 1010 D)

2.5 g 3,3'-thiodipropionic acid dilauryl ester CARN 123-28-4 (Irganox PS 800)

50 g of 2-hydroxy-2-methylpropiophenone, CARN 7473-98-5 (Darocur 1173)

Example 2:

Wording from:

175.0 g butadiene-styrene copolymer without BHT, CARN 9003-55-8 (Stereon 841 A)

595.0 g of terpene hydrocarbon resin modified, CARN 82347-62-4 (Sylvares

ZT 105 LT)

225.0 g polybutadiene 70% 1,2-polymer, stab. with 100ppm BHT, CARN 61789-96-

6 / 9003-17-2 (Ricon 150)

6683-19-8 (Irganox 1010 D)

2.5 g 3,3'-thiodipropionic acid dilauryl ester CARN 123-28-4 (Irganox PS 800)

50 g of 2-hydroxy-2-methylpropiophenone, CARN 7473-98-5 (Darocur 1173) 105 g pentaerythritol-PO adduct-mercaptan-terminated trifunctional, CARN 101359- 87-9 (Capcure 3-800)

Example 3

Example 7

Example 11

IV. Results

1. Thread

The formulations 1 to 11 according to the invention show no or very little thread tension.

2. Creep test (creep test) A) With load

A transparent OPP film (Mobil ROSO 30 LR 400) is glued overlapping 1.5 cm. The adhesive layer thickness is 60 μm. The bond is then irradiated with the H lamp (100% output) at a belt speed of 25 m / min (Fusion Model VPS / I 600). At right angles to the overlap area, test specimens 2.5 cm wide and 10 cm long are cut out, fastened in a circulating air drying cabinet and loaded vertically at 40 ° C with a weight of 210 g. The time until the weight drops is measured. In comparison, unirradiated test specimens and test specimens which are bonded with a commercially available hot melt adhesive for labeling (Euromelt 362 from Henkel KGaA) are also measured. All values are mean values from 6 measurements. Tab. 1: Results for 2 A), creep test with load

B) Without stress

1.) The shrink film (ROSO LR 400, OPP film from Exxon Mobil Chemical) is cut to the following dimensions: 6.7 cm high = not shrinking and 17.9 cm wide with a 6 mm wide clear strip = shrinking

2.) The adhesive is heated to 125-130 ° C and applied by means of an appropriate application device, for example a doctor, application amount: 50-100 g / m ² to a width of 6 mm on the clear section of the film.

3.) A glass plate (preheated in a convection oven at 125 ° C, 15-30 min) with the dimensions: 20 cm x 20 cm x 5 mm serves as a base. Care should be taken to ensure that only the clear section is applied to prevent the entire film from shrinking prematurely.

4.) With the still warm adhesive layer on the foil, an aluminum cup (0 = 50 mm, height = 80 mm, wall thickness: 0.3 mm) is overlapped, i.e. foil on foil, labeled, the glue point with the Finger is pressed well.

5.) The bond is then exposed, the following

Device combination is used: Fusion Model VPS / I 600 with a set maximum power level of 100% (240 W / cm). The spotlight's focus is corrected to the cup diameter, ie set to + 5 cm. The speed range in which measurements are made is between 10 m / min to 50 m / min. The device manufacturer is Fusion UV Systems GmbH in Martinsried, Germany. 6.) The glue point or glued seam is marked with a felt pen and the cup is then stored at 60 ° C in the drying cabinet for 24 hours. 7.) Then the creep value is calculated as the distance from the glue point or

Glued seam measured from the felt tip marker after tempering.

Liability and stickiness are assessed qualitatively.

In all examples 1 to 11, the bond seam shifted by less than 5 mm before tempering compared to after tempering.

V. Description of the measurement methods

♦ melt viscosity Brookfield model RVT DV II, 150 ° C, spindle 27; according to ASTM D 3236-88

♦ Thread tension:

A glass rod is dipped into the hot melt adhesive melted at approx. 160 ° C, slowly pulled out and the rheological behavior of the hot melt adhesive is assessed visually. The assessment includes the manner in which the molten adhesive drips off the glass rod and the formation of adhesive threads during the pulling out of the glass rod from the adhesive melt.

Claims

claims

1. Containing radiation-crosslinkable hotmelt PSA with low tendency to creep

0 to 40% by weight of at least one natural or synthetic, non-radiation-crosslinkable elastomer as component (A),

15 to 40% by weight of at least one compound which contains at least two olefinic double bonds as component (B), and

20 to 85% by weight of a tackifying resin as component (C).

2. Radiation-crosslinkable hot melt pressure sensitive adhesive according to claim 1, containing

15 to 40% by weight of at least one compound which contains at least two olefinic double bonds as component (B),

20 to 85% by weight of a tackifying resin as component (C),

0 to 10% by weight of at least one photoinitiator, photosensitizer and / or regulator molecule as component (D),

0 to 30% by weight of a plasticizer, as component (F),

0 to 30% by weight of a wax as component (G),

0 to 3% by weight of an auxiliary and additive as component (H),

- 0 to 20 wt .-% of non-elastomeric polymers from the group of ethylene-n-butyl acrylate copolymers, ethylene (meth) acrylic acid copolymers, amorphous polyolefins, propylene-butene copolymers, propylene-hexene copolymers and amorphous poly-α Olefins which have been prepared by metallocene catalysis as component (I),

0 to 20% by weight of an adhesion promoter as component (J),

0 to 20% by weight of a polyphenylene oxide (PPO) as component (K), such as

3. Radiation-crosslinkable hot melt pressure sensitive adhesive according to claim 1 or 2, characterized in that component (A) is selected from the group of the elastomers: acrylate, polyester-urethane, ethylene-acrylate, butyl rubber; Natural rubber; Ethylene-propylene copolymers; Ethylene-vinyl acetate copolymers or styrene copolymers, individually or in a mixture, the copolymers being static, alternating, graft or block copolymers.

4. Radiation-crosslinkable hot melt pressure sensitive adhesive according to one of claims 1 to

3, characterized in that component (A) is selected from the group of styrene block polymers, for example styrene and styrene-diene copolymers (SBS, SIS, SBR), styrene-ethylene / butylene copolymers (SEBS) or Styrene-ethylene / propylene-styrene copolymers (SEPS).

5. Radiation-crosslinkable hotmelt pressure-sensitive adhesive according to claim 1 or 2, comprising as component (B) at least one diolefin homo- or copolymer (B1), the proportion of repeating diolefin units in component (B1) being 50 to 100% by weight and component (B1) has olefinic double bonds along the main chain.

6. Radiation-crosslinkable hotmelt pressure-sensitive adhesive according to claim 5, characterized in that as component (B1) homo- or copolymers of 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 1,3-pentadiene, 2-ethyl -1, 3-butadiene, 2-propyl-1, 3-butadiene, 2-isopropyl-1, 3-butadiene, 2-hexyl-1, 3-butadiene, 2,3-dimethyl-1, 3-butadiene, 2 , 3-Diethyl-1, 3-butadiene, 2-methyl-1, 3-pentadiene, 2-methyl-1, 3-hexadiene, 2-methyl-1, 3-octadiene, 2-methyl-1, 3-decadiens , 2,3-dimethyl-1,3-pentadiene, 2,3-dimethyl-1,3-hexadiene, 2,3- Dimethyl-1, 3-octadiens and 2,3-dimethyl-1, 3-decadiens, 2-methyl-1, 3-cyclopentadiens, 2-methyl-1, 3-cyclohectadiens, 2,3-dimethyl-1, 3- cyclopentadiene, 2,3-dimethyl-1, 3-cyclohexadiene, 2-chloro-1, 3-butadiene, 2,3-dichloro-1, 3-butadiene, 1-fluoro-1, 3-butadiene, 2-chloro 1, 3-pentadiene, 2-chloro-1, 3-cyclopentadiene and 2-chloro-1, 3-cyclohexadiene can be used.

7. Radiation-crosslinkable hotmelt pressure-sensitive adhesive according to claim 1 or 2, containing as component (B) at least one diolefin homo- or copolymer (B2), the proportion of repeating diolefin units in component (B2) 50-100

% By weight,

Component (B2) in the side chains and along the main chain olefinic

Has double bonds and the proportion of vinyl double bonds is 5 to 100%, based on the total number of olefinic double bonds in component (B2).

8. Radiation-crosslinkable hotmelt pressure-sensitive adhesive according to claim 1 or 2, characterized in that component (B) as component (B3) is at least one di- and / or higher functional acrylate or methacrylate ester.

9. Radiation-crosslinkable hotmelt adhesive according to one of claims 1 to

8, containing:

5 to 20% by weight of at least one elastomer from the group of the styrene copolymers, ethylene-vinyl acetate copolymers or mixtures of these copolymers as component (A),

0 to 35% by weight of at least one butadiene homo- or copolymer with a 1,2-vinyl content of 30-90% as component (B2),

0 to 35% by weight of at least one diacrylate oligomer as component (B3),

3 to 10% by weight of at least one photoinitiator as component (D)

0.1 to 1% by weight of at least one antioxidant as component <H), 0 to 20% by weight of a plasticizer as component (F), the sum of components (A) to (H) giving 100% by weight.

10.The process for producing the radiation-crosslinkable hotmelt pressure-sensitive adhesive according to any one of claims 1 to 9 by mixing, wherein the optionally plasticizers (component (F)), optionally waxes and resins (components (G) and (C)) at 120 ° C to 180 ° C. are premixed to form a homogeneous melt and, after addition of any auxiliaries and additives (component (H)), if appropriate photoinitiator and / or photosensitizer (component (D)), and if appropriate crosslinking agent containing sulfur groups (component (E)) , the compound containing at least two olefinic double bonds (component (B)), if appropriate the adhesion promoter (component J)) and if appropriate the elastomer (component (A) and / or component (L)) and optionally further non-elastomeric compounds Polymers (component (I)) and optionally polyphenylene oxide (component (K)) are stirred until homogeneous.

11. Use of the radiation-crosslinkable hotmelt pressure-sensitive adhesive according to at least one of claims 1 to 9 and produced according to claim 10 for the adhesive bonding of labels, cardboard closures and books.