DE10010767A1 - Production of an adhesive coated thermoplastic polymer film, useful as an adhesive tape, protective film or a label, comprises treatment of a UV cross-linkable polymer with adhesive and coextrusion. - Google Patents

Abstract

A process for the production of an adhesive coated thermoplastic polymer film (I) comprises treatment of a UV cross-linkable polymer with adhesive and production of the coated polymer film by coextrusion of the adhesive and thermoplastic polymer film.

Description

The invention relates to a method for producing Adhesive-coated thermoplastic polymer films, thereby characterized in that the adhesive is a UV light crosslinkable polymer (polymer for short) and the production the coated polymer film by coextrusion of the adhesive and the thermoplastic polymer film (short film) follows.

UV-crosslinkable copolymers are known to be suitable as what water and solvent free hot melt pressure sensitive adhesives. You can as Melt applied to labels, adhesive tapes or foils the. Then a molecular weight build-up is achieved by UV radiation and crosslinking so that the adhesive layer also the has the necessary cohesion. The coating of the substrates with the UV-curable adhesive can be made by different methods respectively. Is known for. B. also UV-crosslinkable copolymers or hotmelt adhesives on carrier, e.g. B. thermoplastic Extrude foils. Such methods are u. a. EP-A-367 054, DE-A-37 28 991, DE-A-39 42 232 and EP-A-621 326 ge called.

All processes have in common that the thermoplastic film is next manufactured separately and then the coating he follows.

The object of the present invention was a simple ches and cost-effective method for producing with adhesive fabric coated straps.

Accordingly, the process defined at the outset was found.

In the adhesive used in the method according to the invention it is a polymer that can be crosslinked with UV light.

The polymer contains a photoinitia for crosslinking with UV light goal. The photoinitiator can be bound to the polymer, it can but also unbound and only mixed with the polymer his.  

Common photo initiator that can be added to the polymer are z. B. acetophenone, benzoin ether, benzyl dialkyl ketones or their derivatives.

The content of the admixed photo initiator is preferably 0.05 to 10 parts by weight, particularly preferably 0.1 to 2 parts by weight per 100 parts by weight of polymer.

The photoinitiator is preferably bound to the polymer.

The polymer is ethylenically radical polymerized Unsaturated radical-polymerizable compounds Lich.

In the preferred case that the photoinitiator is attached to the polymer is bound, preferably an ethylenically unsaturated Ver binding with a photoinitiator group by copolymerization bound.

By irradiation with high-energy light, especially UV Light is caused by the photoinitiator or by the polymer dene photoinitiator group a crosslinking of the polymer, preferably wise by a chemical graft reaction of the photoinitiator group with a spatially adjacent polymer chain. In particular, can cross-linking by inserting a carbonyl group of the Fotoini tiators in an adjacent C-H bond to form a -C-C-O-H grouping.

The wavelength range in which the photo initiator or photo initiator group can be activated, d. H. in which the main sub sorption band of the photoinitiator group is preferred 200 to 450 mm, particularly preferably 230 to 350, very particularly preferably 230 to 280 mm.

The polymer which can be crosslinked with UV light preferably consists of 50 to 99.95% by weight, preferably 60 to 99.9, very particularly preferably 80 to 99.9% by weight of C ₁ to C ₁₈ alkyl ( meth) acrylates. Preferred are C ₁ -C ₁₀ alkyl (meth) acrylates, e.g. B. methyl acrylate, methyl methacrylate, n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylates. Mixtures of the alkyl (meth) acrylates are used in particular.

The polymer is in the case of the polymerized photoinitiator furthermore 0.05 to 10% by weight, preferably 0.1 to 2% by weight and particularly preferably 0.1 to 1% by weight of ethylenic unsaturated compounds with a photoinitiator group.  

For the ethylenically unsaturated compound with a photoini tiatorgruppe is preferably an acetophenone or particularly preferably a benzophenone derivative.

Suitable compounds are acetophenone or benzophenone derivatives which have at least one, preferably one ethylenic contain unsaturated group. With the ethylenically unsaturated Group is preferably an acrylic or meth acrylic group.

The ethylenically unsaturated group can be attached directly to the phenyl ring of the acetophenone or benzophenone derivative. in the general is between phenyl ring and ethylenic unsaturated group a spacer group (spacer).

The spacer group can e.g. B. contain up to 100 carbon atoms.

Suitable acetophenone or benzophenone derivatives are e.g. B. in EP-A-346 734, EP-A-377199 (1st claim), DE-A-40 37 079 (1st claim) and DE-A-38 44 444 (1st claim) are described and are by this reference also in the present application. Preferred acetophenone and benzophenone derivatives are those of the formula

wherein R ^{1 is} an organic radical having up to 30 C atoms, R ^{2 is} an H atom or a methyl group and R ^{3 is} an optionally substituted phenyl group or a C ₁ -C ₄ alkyl group.

R ¹ particularly preferably represents an alkylene group, in particular a C ₂ -C ₈ alkylene group.

R ³ particularly preferably represents a methyl group or a phenyl group.

The polymer can contain other ethylenically unsaturated compounds included as structural components. May be mentioned for. B. vinyl esters of up to 20 carbon atoms containing carboxylic acids, vinyl aromatics with up to 20 carbon atoms, ethylenically unsaturated nitriles, vinyl halides, vinyl ethers of 1 to 10 carbon atoms containing Alko  fetch, aliphatic hydrocarbons with 2 to 8 carbon atoms and 1 or 2 double bonds or mixtures of these monomers.

Vinyl esters of carboxylic acids with 1 to 20 carbon atoms are e.g. B. Vinyl laurate, stearate, vinyl propionate, vinyl versatic acid and vinyl acetate.

The vinyl aromatic compounds are vinyl toluene a- and p-Me thylstyrene, a-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene and preferably styrene. Examples of nitriles are Acrylonitrile and methacrylonitrile.

The vinyl halides are substituted with chlorine, fluorine or bromine ethylenically unsaturated compounds, preferably vinyl chloride and Vinylidene chloride.

Examples of vinyl ethers include B. vinyl methyl ether or vinyl isobutyl ether. Vinyl ether of 1 to 4 carbon atoms is preferred keeping alcohols.

As hydrocarbons with 2 to 8 carbon atoms and two olefinic Double bonds are butadiene, isoprene and chloroprene.

The polymer can also monomers with carboxylic acid, sulfonic acid or contain phosphonic acid groups. Carboxylic acids are preferred groups. May be mentioned for. B. acrylic acid, methacrylic acid, itacon acid, maleic acid or fumaric acid.

Other monomers are e.g. B. also containing hydroxyl groups Monomers, (meth) acrylamide, (meth) acrylonitrile or phenyloxyethyl glycol mono- (meth -) - acrylate, glycidyl acrylate, glycidyl methacrylate, amino (meth -) - called acrylates such as 2-aminoethyl (meth) acrylate.

The polymer preferably has a K value of 30 to 80 particularly preferably from 40 to 60, measured in 1% solution, (Solvent: tetrahydrofuran, 23 ° C).

The Fikentscher K value is a measure of the molecular weight and viscosity of the polymer.

The glass transition temperature (Tg) of the polymer is preferably -60 to + 10 ° C, particularly preferably -55 to 0 ° C, whole particularly preferably -55 to -20 ° C.  

The glass transition temperature of the polymer can be reduced usual methods such as differential thermal analysis or differential Scanning calorimetry (see, for example, ASTM 3418/82, so-called "midpoint temperature ".

The UV-usable polymers can be obtained by copolymerization of the monomeric components using the usual polymer onsinitiators and possibly made by regulators the, whereby one at the usual temperatures in substance, in Emulsion, e.g. B. in water or liquid hydrocarbons, or polymerized in solution. The polymers are preferably by Polymerization of the monomers in solvents, especially in Solvents with a boiling range of 50 to 150 ° C, preferably from 60 to 120 ° C using the usual amounts of polyme risk initiators, generally at 0.01 to 10, ins especially at 0.1 to 4 wt .-%, based on the total weight of the Monomers is made. As a solvent come in special alcohols, such as methanol, ethanol, n- and iso-propanol, n- and iso-butanol, preferably isopropanol and / or isobutanol and hydrocarbons such as toluene and especially gasolines a boiling range of 60 to 120 ° C in question. Can also Ketones such as acetone, methyl ethyl ketone and esters with acetic acid ethyl esters and mixtures of solvents of the type mentioned are used, mixtures which contain isopropanol and / or iso butanol in amounts of 5 to 95, in particular 10 to 80, preferably from 25 to 60% by weight, based on the amount used Mixed solution, included, are preferred.

The solution initiators come as polymerization initiators merization, for example, azo compounds or ketone peroxides Consideration.

After the polymerization in solution, the solvents can be countered are also separated off under reduced pressure, at elevated temperatures, for example in the range from 100 to 150 ° C works. The polymers can then in solvent free state, d. H. used as melts. In some In cases it is also advantageous to use the UV-crosslinkable polymers by bulk polymerization, d. H. without using one Solvent to produce, being batch or continuously, e.g. B. according to the information in US Pat. No. 4,042,768 can.  

The polymers are preferred in the process according to the invention as a melt, d. H. essentially solvent-free (solution average content preferably less than 2 wt .-%, based on the poly mer), used.

However, the polymer can also be in the form of a solution or dispersion be used in organic solvents or water. In the event of Such a dispersion or solution can separate the Lö medium or water during the coextrusion of the polymer respectively.

The polymer can be added before or during coextrusion fabrics, e.g. B. fillers, pigments or soluble dyes added be set.

In the method according to the invention, this is described above bene polymer and the thermoplastic polymer film co-extruded and so produced the polymer film coated with adhesive.

The thermoplastic polymer film is ins especially a polymer film, preferably a film made of Polyethylene or polypropylene.

However, it can also be polyester films or polyacetate films act.

Several polymer films can also be coextruded, so that a film composite is obtained. The outer film of the film ver bunds is then coated with the adhesive.

There is also the possibility of both surfaces of the poly mer film or the film composite by coextrusion with the adhesive to coat fabric.

The thickness of the adhesive layer on the obtained coated The film is preferably 1 μm to 100 μm, particularly preferably 1 up to 25 µm.

For the extruders for the adhesive and for the thermoplastic Molding compound of the polymer film can be z. B. a Einschnec or a twin-screw extruder.

In the case of the adhesive, it can also be a barrel melter act in which the adhesive is melted and then with a melt pump z. B. a gear pump to the coextrusion plant stuff is transported.  

The temperature of the adhesive as it exits the coextrusion tool is preferably 80 to 170 ° C, particularly preferably 90 up to 140 and very particularly preferably 100 to 130 ° C.

The temperature of the thermoplastic molding compound when it exits the coextrusion die is preferably 100 to 300 ° C., in particular preferably 170 to 250 ° C.

The melt flow of the polymer and the thermoplastic form mass can be separated in the coextrusion die and after Aus occurs from the coextrusion tool. The Melt flow of the polymer and the thermoplastic molding compound can also be merged in the coextrusion tool become.

In the coextrusion tool it can be, for. B. a tool for adapter coextrusion, a feed block, a multi-layer nozzle (when merging the melt streams in the coextrusion die) or several wide slot nozzles (with separate melt flow in the Act on top of each other.

The film obtained can, after cooling (whereby), be wound up and processed further at a later date.

The radiation is preferably carried out before the film is wound up with high-energy light, preferably UV light or electrons shine. The film can do this after leaving the coextrusion tool directly at the radiation source, e.g. B. a UV lamp or be guided by a laser.

The radiation energy is preferably 100 to 1500 mJ / cm ² irradiated area, measured over the entire emitted wavelength range (with the UV Power Puck®).

The film is suitable as an adhesive film, e.g. B. protective film, or for Adhesive tapes or labels.

Claims (13)

1. A process for the production of adhesive-coated thermoplastic polymer films, characterized in that the adhesive is a polymer which can be crosslinked with UV light (polymer for short) and the production of the polymer film be coated by coextrusion of the adhesive and the thermoplastic polymer film (short Called slide) he follows. 2. The method according to claim 1, characterized in that the polymer consists of at least 50 wt .-% of C ₁ to C ₁₈ alkyl (meth) acrylates. 3. The method according to claim 1 or 2, characterized in that the polymer has a K value of 30 to 80, measured in Has tetrahydrofuran at 23 ° C. 4. The method according to any one of claims 1 to 3, characterized records that the polymer has a glass transition temperature of -60 to + 10 ° C. 5. The method according to any one of claims 1 to 4, characterized shows that the film is a thermoplastic, is preferably a polyolefin film. 6. The method according to any one of claims 1 to 5, characterized records that the thickness of the adhesive layer on the Coated film obtained is 1 micron to 100 microns. 7. The method according to any one of claims 1 to 6, characterized characterizes that the temperature of the adhesive at exit the coextrusion die is 80 ° C to 170 ° C. 8. The method according to any one of claims 1 to 7, characterized records that the temperature of the thermoplastic molding composition the film exits the coextrusion die from 100 ° C to Is 300 ° C. 9. The method according to any one of claims 1 to 7, characterized records that the melt flow of the polymer and thermoplastic molding compound of the film in the coextrusion die is merged.   10. The method according to claim 9, characterized in that the Temperature of the combined melt flow as it exits the coextrusion die is 80 ° C to 300 ° C. 11. The method according to any one of claims 1 to 10, characterized records that it is the extruder for the adhesive a single screw or twin screw extruder or one Barrel melter if necessary in combination with a melt pump acts. 12. The method according to any one of claims 1 to 11, characterized records that it is in the extruder for the thermoplastic cal molding compound of the film around a single screw or double screw extruder. 13. The method according to any one of claims 1 to 12, characterized records that the coextrusion tool is a Tool for adapter coextrusion, one feed block, one Multi-layer nozzle or several wide slot nozzles one above the other acts.