OXAZOLINE-CONTAINING AQUEOUS POLYMER DISPERSIONS FOR COMPOSITE FILM LAMINATION

Abstract

Described are aqueous polymer dispersions for composite film lamination and a multistage process for preparing them from ethylenically unsaturated, radically polymerizable monomers. In a first stage, a first polymer is prepared by radical emulsion polymerization. In a further stage, an aqueous polymer dispersion is prepared in the presence of the first polymer. The monomers of the first stage comprise monomers with acid groups. The monomers of the further stage comprise monomers having oxazoline groups. The polymerization of the first stage takes place at a low pH of less than 5. The acid groups of the first polymer are neutralized before the polymerization of the further stage. The aqueous polymer dispersions can be used as adhesives for producing composite films.

Claims

1. An aqueous polymer dispersion for composite film lamination, said polymer dispersion prepared by a radical emulsion polymerization process comprising: initially, in a first stage in aqueous medium, preparing a first polymer dispersed in water by performing a radical emulsion polymerization, the first polymer being prepared from a first composition comprising ethylenically unsaturated, radically polymerizable monomers; and in a further stage, a polymer dispersion is prepared in aqueous medium and in the presence of the first polymer by radical emulsion polymerization of a further composition, which is different from the first composition and comprises ethylenically unsaturated, radically polymerizable monomers, wherein: the monomers of the first stage comprise at least one monomer having at least one acid group, in an amount of at least 0.1 part by weight, based on 100 parts by weight of the monomers of all stages; the monomers of the further stage comprise at least one monomer having at least one oxazoline group; the polymerization of the first stage occurs at a pH less than 5 and, before the polymerization of the further stage, acid groups are neutralized with a volatile base to an extent such that the pH of the polymer dispersion before the further stage is greater than 5; less than 0.5 part by weight, based on 100 parts by weight of monomers, of an emulsifier is optionally present in the radical emulsion polymerization process; and a glass transition temperature of a polymer prepared by the radical emulsion polymerization process is less than 10 C.

2. The polymer dispersion of claim 1, wherein the at least one monomer having at least one oxazoline group is used exclusively in the further stage and in an amount of 0.5 to 4 parts by weight per 100 parts by weight of the radically polymerizable monomers.

3. The polymer dispersion of claim 1, wherein the at least one monomer having at least one oxazoline group is a monomer of formula: ##STR00003## in which: R is a C.sub.2-20 alkenyl radical comprising at least one ethylenically unsaturated group; and R.sup.3, R.sup.4, R.sup.5, and R.sup.6 are selected independently of one another from the group consisting of H, halogen, C.sub.1-20 alkyl, C.sub.2-20 alkenyl, C.sub.6-20 aryl, C.sub.7-32 arylalkyl, C.sub.1-20 hydroxyalkyl, C.sub.1-20 aminoalkyl, and C.sub.1-20 haloalkyl.

4. The polymer dispersion of claim 1, wherein the at least one monomer having at least one oxazoline group is selected from the group consisting of 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-vinyl-4-ethyl-2-oxazoline, 2-vinyl-4,4-dimethyl-2-oxazoline, 2-vinyl-5,5-dimethyl-2-oxazoline, 2-vinyl-4,4,5,5-tetramethyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, 2-isopropenyl-4-ethyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, 2-isopropenyl-4,4-dimethyl-2-oxazoline, 2-isopropenyl-5,5-dimethyl-2-oxazoline and 2-isopropenyl-4,4,5,5-tetramethyl-2-oxazoline.

5. The polymer dispersion of claim 1, wherein, in the first stage, monomers comprising acid groups are copolymerized with monomers without acid groups, and a weight ratio of the monomers comprising acid groups to the monomers without acid groups ranges from 5:95 to 15:85.

6. The polymer dispersion of claim 5, wherein: the monomers comprising acid groups are selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, vinylacetic acid, vinyllactic acid, unsaturated phosphonic acids, and mixtures of these monomers; and the monomers without acid groups are selected from the group consisting of C1 to C10 alkyl acrylates, C1 to C10 alkyl methacrylates, and mixtures of these monomers.

7. The polymer dispersion of claim 1, wherein at least 60% by weight of the monomers used in the further stage are selected from the group consisting of C1 to C20 alkyl acrylates, C1 to C20 alkyl methacrylates, vinyl esters of carboxylic acids comprising up to 20 C atoms, vinylaromatics having up to 20 C atoms, ethylenically unsaturated nitriles, vinyl halides, vinyl ethers of alcohols comprising 1 to 10 C atoms, aliphatic hydrocarbons having 2 to 8 C atoms and one or two double bonds, and mixtures of these monomers.

8. The polymer dispersion of claim 1, wherein polymers formed in all stages of the radical emulsion polymerization are polymers which apart from acid monomers and monomers comprising oxazoline groups are formed exclusively of derivatives of (meth)acrylic acid.

9. The polymer dispersion of claim 1, wherein a chain transfer agent is present during the first stage.

10. The polymer dispersion of claim 1, wherein a weight ratio of monomers used in the first stage to monomers used in the further stage is from 10:90 to 65:35.

11. The polymer dispersion of claim 1, wherein the polymerization of the first stage takes place in the presence of a seed latex.

12. The polymer dispersion of claim 1, wherein the monomers used in the further stage comprise not more than 1 part by weight, based on 100 parts by weight, of monomers with acid groups, or comprise no monomers with acid groups.

13. A process for preparing an aqueous polymer dispersion for composite film lamination, the process comprising: initially, in a first stage in aqueous medium,. preparing a first polymer dispersed in water by performing a radical emulsion polymerization, the first polymer being prepared from a first composition comprising ethylenically unsaturated, radically polymerizable monomers; and in a further stage, a polymer dispersion is prepared in aqueous medium and in the presence of the first polymer by radical emulsion polymerization of a further composition, which is different from the first composition and comprises ethylenically unsaturated, radically polymerizable monomers, wherein: the monomers of the first stage comprise at least one monomer having at least one acid group, in an amount of at least 0.1 part by weight, based on 100 parts by weight of the monomers of all stages; and the monomers of the further stage comprise at least one monomer having at least one oxazoline group; the polymerization of the first stage occurs at a pH less than 5 and, before the polymerization of the further stage, acid groups are neutralized with a volatile base to an extent such that the pH of the polymer dispersion before the further stage is greater than 5; where in total less than 0.5 part by weight, based on 100 parts by weight of monomers, of an emulsifier is optionally present in the radical emulsion polymerization process; and a glass transition temperature of a polymer prepared by the radical emulsion polymerization process is less than 10 C.

14. A laminating adhesive, comprising the aqueous polymer dispersion of claim 1.

15. A composite film, comprising first film and at least one second film, which are bonded to one another using an adhesive comprising the aqueous polymer dispersion of claim 1.

16. A process for producing composite films, the process comprising bonding at least two films with one another using the aqueous polymer dispersion of claim 1.

Description

EXAMPLES

[0082] Determination of Particle Size

[0083] The particle size is determined by hydrodynamic fractionation using a PSDA (Particle Size Distribution Analyzer) from Polymer Labs. The CartridgePL0850-1020 column type used is operated with a flow rate of 2 ml/min. The samples are diluted to an absorption of 0.03 AU/l with the eluent solution. The sample is eluted, through the size exclusion principle, in dependence on the hydrodynamic diameter 10. The eluent contains 0.2% by weight of dodecyl poly(ethylene glycol ether)23, 0.05% by weight of sodium dodecyl sulfate, 0.02% by weight of sodium dihydrogenphosphate, and 0.02% by weight of sodium azide in deionized water. The pH is 5.8. The elution time is calibrated using polystyrene latices. Measurement takes place in the 20 nm to 1200 nm range. Detection is carried out using a UV detector at a wavelength of 254 nm.

[0084] Determination of Glass Transition Temperature:

[0085] The glass transition temperature is measured by means of differential scanning calorimetry in accordance with ASTM D 3418-08. For conditioning, the polymers are poured out, dried overnight, then dried at 120 C. in a vacuum drying cabinet for 1 hour. At measurement, the sample is heated to 150 C., cooled rapidly, and then measured on heating at 20 C./min up to 150 C. The value reported is the mid-point temperature.

Example 1

Two-Stage Polymer Dispersion (2.36 pphm IPOx Tg 32 C.).

[0086] A 2L reactor with anchor stirrer, heated to 80 C., was filled with 5.9 g of a polystyrene seed (solids content: 33%, particle size: 30 nm) and 166.5 g of deionized water. When the internal temperature reached 80 C., 46.4 g of 7% strength sodium peroxodisulfate solution were added and the mixture was stirred for 2 minutes. This was followed by the metered addition over 60 minutes of 274.4 g of an emulsion consisting of 92.7 g of deionized water, 6.5 g of itaconic acid, 3.3 g of methacrylic acid, 1.2 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 110.5 g of n-butyl acrylate, 34.1 g of methyl acrylate, and 13.0 g of styrene. At the same time the reaction temperature was raised to 85 C. over 60 minutes. After the end of the first emulsion feed, the pH was adjusted to 7.5 using 3.7% strength ammonia over 10 minutes. Then a second emulsion feed, consisting of 92.7 g of deionized water, 4.6 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 29.3 g of styrene, 423.4 g of n-butyl acrylate, 15.3 g of isopropenyloxazoline, and 14.6 g of methyl acrylate, was metered in over 120 minutes. After the end of the feed, 41.6 g of deionized water were added and the temperature was lowered to 80 C. At an internal temperature of 80 C., 35.5 g of acetone bisulfite (7% strength) and 13.0 g of tert-butyl hydroperoxide (10% strength) were metered in over 60 minutes. This was followed by the addition of 0.3 g of ammonia (25% strength) and 41.6 g of deionized water, and the experiment was cooled to room temperature. After cooling, the dispersion was filtered through a 125 m Perlon filter. The dispersion had a solids content of 49.8%, a pH of 7.4, an overall glass transition temperature of 32 C., and a particle size of 222 nm.

Example 2

Two-Stage Polymer Dispersion (1 pphm IPOx)

[0087] A 2L reactor with anchor stirrer, heated to 80 C., was filled with 6.1 g of a polystyrene seed (SC: 33%, PS: 30 nm) and 163.2 g of deionized water. When the internal temperature reached 80 C., 45.0 g of 7% strength sodium peroxodisulfate solution were added and the mixture was stirred for 2 minutes. This was followed by the metered addition over 120 minutes of 302.7 g of an emulsion consisting of 163.04 g of deionized water, 6.3 g of itaconic acid, 3.15 g of acrylic acid, 3.4 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 173.6 g of n-butyl acrylate, 192.0 g of methyl acrylate, and 0.6 g of 2-ethylhexyl thioglycolate. At the same time the reaction temperature was raised to 85 C. over 60 minutes. After the end of the first emulsion feed, the pH was adjusted to 7 using 5% strength ammonia over 10 minutes. Then a second emulsion feed, consisting of 45.6 g of deionized water, 2.3 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 6.3 g of isopropenyloxazoline, 143.8 g of n-butyl acrylate, and 104.8 g of methyl acrylate was metered in in 70 minutes. After the end of the feed, 31.5 g of deionized water were added and the temperature was lowered to 80 C. At an internal temperature of 80 C., 50.2 g of acetone bisulfite (4.8% strength) and 12.6 g of tert-butyl hydroperoxide (10% strength) were metered in over 60 minutes. This was followed by the addition of 34.3 g of deionized water, and the experiment was cooled to room temperature. After cooling, the dispersion was filtered through a 125 m Perlon filter. The dispersion had a solids content of 50.7%, a pH of 7.0, an overall glass transition temperature of 16 C., and a particle size of 206 nm.

Example 3

Three-Stage Polymer Dispersion (2 pphm IPOx, Tg=15 C.)

[0088] A 2L reactor with anchor stirrer, heated to 80 C., was filled with 6.1 g of a polystyrene seed (SC: 33%, PS: 30 nm) and 168.8 g of deionized water. When the internal temperature had reached 80 C., 45 g of a 7% strength sodium peroxodisulfate solution were added and the mixture was stirred for 2 minutes. This was followed by the metered addition over 60 minutes of 238.9 g of an emulsion consisting of 117.4 g of deionized water, 6.3 g of itaconic acid, 1.1 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 29.9 g of n-butyl acrylate, 83.5 g of methyl acrylate, and 0.6 g of 2-ethylhexyl thioglycolate. At the same time the reaction temperature was raised to 85 C. over 60 minutes. After the end of the first emulsion feed, a second emulsion feed took place, consisting of 45.6 g of deionized water, 3.2 g of acrylic acid, 2.3 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 143.8 g of n-butyl acrylate, and 108.5 g of methyl acrylate, which was metered in over 60 minutes. 15 minutes after the start of the second emulsion feed, a separate feed of 56.7 g of 5% strength ammonia was metered in at the same time over 45 minutes. When the second emulsion feed and the ammonia feed had ended, a third emulsion feed was metered in over 60 minutes, comprising 45.6 g of fully demineralized water, 2.3 g of sodium lauryl polyethoxy-sulfate (Disponil FES 27, 28% strength in water, BASF SE), 140.7 g of n-butyl acrylate, 101.6 g of methyl acrylate, and 12.6 g of isopropenyloxazoline. After the end of the feed, 31.5 g of deionized water were added and the temperature was lowered to 80 C. At an internal temperature of 80 C., 8.7 g of acetone bisulfite (13.2% strength) and 12.6 g of tert-butyl hydroperoxide (10% strength) were metered in over 60 minutes. This was followed by addition of 34.3 g of deionized water and by the cooling of the experiment to room temperature. After cooling, the dispersion was filtered through a 125 m Perlon filter. The dispersion had a solids content of 49.1%, a pH of 6.5, an overall glass transition temperature of 15 C., and a particle size of 179 nm.

Example 4

Three-Stage Polymer Dispersion (1.8 pphm IPOx, 14 C.)

[0089] A 2L reactor with anchor stirrer, heated to 80 C., was filled with 6.11 g of a polystyrene seed (SC: 33%, PS: 30 nm) and 172.0 g of deionized water. When the internal temperature had reached 80 C., 45 g of a 7% strength sodium peroxodisulfate solution were added and the mixture was stirred for 2 minutes. This was followed by the metered addition over 60 minutes of 238.9 g of an emulsion consisting of 117.4 g of deionized water, 6.3 g of itaconic acid, 1.1 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 29.9 g of n-butyl acrylate, 83.5 g of methyl acrylate, and 0.6 g of 2-ethylhexyl thioglycolate. At the same time the reaction temperature was raised to 85 C. over 60 minutes. After the end of the first emulsion feed, a second emulsion feed took place, consisting of 45.6 g of deionized water, 0.63 g of acrylic acid, 2.3 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 6.3 g of 2-hydroxypropyl acrylate, 140.7 g of n-butyl acrylate, and 107.9 g of methyl acrylate, which was metered in over 60 minutes. 15 minutes after the start of the second emulsion feed, a separate feed of 51.7 g of 3.66% strength ammonia was metered in at the same time over 45 minutes. When the second emulsion feed and the ammonia feed had ended, a third emulsion feed was metered in over 60 minutes, comprising 45.6 g of fully demineralized water, 2.3 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 6.3 g of 2-hydroxypropyl acrylate, 140.7 g of n-butyl acrylate, 96.2 g of methyl acrylate, and 11.7 g of isopropenyloxazoline. After the end of the feed, 31.5 g of deionized water were added and the temperature was lowered to 80 C. At an internal temperature of 80 C., 8.7 g of acetone bisulfite (13.2% strength) and 12.6 g of tert-butyl hydroperoxide (10% strength) were metered in over 60 minutes. This was followed by addition of 34.3 g of deionized water and by the cooling of the experiment to room temperature. After cooling, the dispersion was filtered through a 125 m Perlon filter. The dispersion had a solids content of 48.9%, a pH of 7.5, an overall glass transition temperature of 14 C., and a particle size of 174 nm.

Example 5

Three-Stage Polymer Dispersion (1.4 pphm IPOx)

[0090] A 2L reactor with anchor stirrer, heated to 80 C., was filled with 6.11 g of a polystyrene seed (SC: 33%, PS: 30 nm) and 172.0 g of deionized water. When the internal temperature had reached 80 C., 45 g of a 7% strength sodium peroxodisulfate solution were added and the mixture was stirred for 2 minutes. This was followed by the metered addition over 60 minutes of 238.9 g of an emulsion consisting of 117.4 g of deionized water, 6.3 g of itaconic acid, 1.1 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 29.9 g of n-butyl acrylate, 83.5 g of methyl acrylate, and 0.6 g of 2-ethylhexyl thioglycolate. At the same time the reaction temperature was raised to 85 C. over 60 minutes. After the end of the first emulsion feed, a second emulsion feed took place, consisting of 45.6 g of deionized water, 0.63 g of acrylic acid, 2.3 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 6.3 g of 2-hydroxypropyl acrylate, 140.7 g of n-butyl acrylate, and 107.9 g of methyl acrylate, which was metered in over 60 minutes. 15 minutes after the start of the second emulsion feed, a separate feed of 51.7 g of 3.66% strength ammonia was metered in at the same time over 45 minutes. When the second emulsion feed and the ammonia feed had ended, a third emulsion feed was metered in over 60 minutes, comprising 45.6 g of fully demineralized water, 2.3 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 6.3 g of 2-hydroxypropyl acrylate, 140.7 g of n-butyl acrylate, 99.1 g of methyl acrylate, and 8.82 g of isopropenyloxazoline. After the end of the feed, 31.5 g of deionized water were added and the temperature was lowered to 80 C. At an internal temperature of 80 C., 8.7 g of acetone bisulfite (13.2% strength) and 12.6 g of tert-butyl hydroperoxide (10% strength) were metered in over 60 minutes. This was followed by addition of 34.3 g of deionized water and by the cooling of the experiment to room temperature. After cooling, the dispersion was filtered through a 125 m Perlon filter. The dispersion had a solids content of 49.7%, a pH of 7, an overall glass transition temperature of 14 C., and a particle size of 183 nm.

Example 6

Three-Stage Polymer Dispersion (0.5 pphm IPOx)

[0091] A 2L reactor with anchor stirrer, heated to 80 C., was filled with 6.1 g of a polystyrene seed (SC: 33%, PS: 30 nm) and 172.0 g of deionized water. When the internal temperature had reached 80 C., 45 g of a 7% strength sodium peroxodisulfate solution were added and the mixture was stirred for 2 minutes. This was followed by the metered addition over 60 minutes of 238.9 g of an emulsion consisting of 117.4 g of deionized water, 6.3 g of itaconic acid, 1.1 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 29.9 g of n-butyl acrylate, 83.5 g of methyl acrylate, and 0.6 g of 2-ethylhexyl thioglycolate. At the same time the reaction temperature was raised to 85 C. over 60 minutes. After the end of the first emulsion feed, a second emulsion feed took place, consisting of 45.6 g of deionized water, 0.63 g of acrylic acid, 2.3 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 6.3 g of 2-hydroxypropyl acrylate, 140.7 g of n-butyl acrylate, and 107.9 g of methyl acrylate, which was metered in over 60 minutes. 15 minutes after the start of the second emulsion feed, a separate feed of 51.7 g of 3.7% strength ammonia was metered in at the same time over 45 minutes. When the second emulsion feed and the ammonia feed had ended, a third emulsion feed was metered in over 60 minutes, comprising 45.6 g of fully demineralized water, 2.3 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 6.3 g of 2-hydroxypropyl acrylate, 140.7 g of n-butyl acrylate, 104.9 g of methyl acrylate, and 3.0 g of isopropenyloxazoline. After the end of the feed, 31.5 g of deionized water were added and the temperature was lowered to 80 C. At an internal temperature of 80 C., 8.7 g of acetone bisulfite (13.2% strength) and 12.6 g of tert-butyl hydroperoxide (10% strength) were metered in over 60 minutes. This was followed by addition of 34.3 g of deionized water and by the cooling of the experiment to room temperature. After cooling, the dispersion was filtered through a 125 m Perlon filter. The dispersion had a solids content of 49.6%, a pH of 7, an overall glass transition temperature of 15 C., and a particle size of 198 nm.

Comparative example 7

No IPOx

[0092] A 2L reactor with anchor stirrer, heated to 80 C., was filled with 5.8 g of a polystyrene seed (SC: 33%, PS: 30 nm) and 163.8 g of deionized water. When the internal temperature reached 80 C., 42.9 g of 7% strength sodium peroxodisulfate solution were added and the mixture was stirred for 2 minutes. This was followed by the metered addition over 60 minutes of 227.5 g of an emulsion consisting of 111.8 g of deionized water, 6.0 g of itaconic acid, 1.1 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 28.5 g of n-butyl acrylate, 79.6 g of methyl acrylate, and 0.6 g of 2-ethylhexyl thioglycolate. At the same time the reaction temperature was raised to 85 C. over 60 minutes. After the end of the first emulsion feed, a second emulsion feed, consisting of 86.8 g of deionized water, 0.6 g of acrylic acid, 4.3 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 12.0 g of 2-hydroxypropyl acrylate, 267.9 g of n-butyl acrylate, and 205.5 g of methyl acrylate was metered in over 120 minutes. 15 minutes after the second emulsion feed was started, 3.66% strength ammonia was metered in via a separate feed, over 105 minutes, in a quantity of 49.2 g. After the end of the feed, 30.0 g of deionized water were added and the temperature was lowered to 80 C. At an internal temperature of 80 C., 8.2 g of acetone bisulfite (13.2% strength) and 12.0 g of tert-butyl hydroperoxide (10% strength) were metered in over 60 minutes. This was followed by the addition of 0.2 g of ammonia (25% strength) and 32.7 g deionized water, and the experiment was cooled to room temperature. After cooling, the dispersion was filtered through a 125 m Perlon filter. The dispersion had a solids content of 50.7%, a pH of 6.5, an overall glass transition temperature of 15 C., and a particle size of 185 nm (hydrodynamic chromatography).

Comparative example 8

Emulsifier-Containing

[0093] A 2L reactor with anchor stirrer, heated to 80 C., was filled with 6.1 g of a polystyrene seed (SC: 33%, PS: 30 nm) and 163.2 g of deionized water. When the internal temperature reached 80 C., 45.0 g of 7% strength sodium peroxodisulfate solution were added and the mixture was stirred for 2 minutes. This was followed by the metered addition over 120 minutes of 310.9 g of an emulsion consisting of 140.9 g of deionized water, 6.3 g of itaconic acid, 3.15 g of acrylic acid, 40.5 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 173.6 g of n-butyl acrylate, 192.0 g of methyl acrylate, and 0.6 g of 2-ethylhexyl thioglycolate. At the same time the reaction temperature was raised to 85 C. over 60 minutes. After the end of the first emulsion feed, the pH was adjusted to 7 using 5% strength ammonia over 15 minutes. Then a second emulsion feed, consisting of 23.0 g of deionized water, 27.0 g of sodium lauryl polyethoxysulfate (Disponil FES 27, 28% strength in water, BASF SE), 6.3 g of isopropenyloxazoline, 143.8 g of n-butyl acrylate, and 104.8 g of methyl acrylate was metered in in 70 minutes. After the end of the feed, 31.5 g of deionized water were added and the temperature was lowered to 80 C. At an internal temperature of 80 C., 50.2 g of acetone bisulfite (4.8% strength) and 12.6 g of tert-butyl hydroperoxide (10% strength) were metered in over 60 minutes. This was followed by the addition of 44.8 g of deionized water, and the experiment was cooled to room temperature. After cooling, the dispersion was filtered through a 125 m Perlon filter. The dispersion had a solids content of 49.4%, a pH of 7.0, an overall glass transition temperature of 16 C., and a particle size of 172 nm.

[0094] Production of Composite Films:

[0095] The neutralized polymer dispersions are knife-coated in a dry film thickness of 2 g/m.sup.2 (based on the solids content) onto commercial films (OPP-ink; printed oriented polypropylene). After hot-air drying, the films thus coated are rolled up with a second film (metalized cast PP) and then pressed under a pressure of 6.5 bar and at 70 C. in a roller press at 5 m/min. The composite films are subsequently stored for 1 day at room temperature under standard conditions.

[0096] Determination of Peel Strength (Instantaneous Adhesion and Heat Stability):

[0097] For the determination of the peel strength, the composite films are cut up into strips 15 mm wide. The strips are then peeled at an angle of 290 (180 and at a speed of 100 mm/min at 23 C. in a universal testing machine for peel strengths, from Zwick (model 1120.25.01), and the force required to achieve this is recorded, in newtons. To determine the instantaneous adhesion, the peel strength was recorded after 1 minute at 23 C. To determine the heat stability, the peel strength was recorded at 90 C. in a heated chamber. In order to describe the chemical resistance of the adhesives, the laminates were stored in tomato ketchup at 50 C. for 7 days, after which their peel strengths were determined at 23 C. The results are compiled in Table 1.

TABLE-US-00001 TABLE 1 Test results, peel strength Peel strength after Peel strength after Heat stability at 90 C. storage in ketchup Example 24 h [N/15 mm] [N/15 mm] [N/15 mm] 1 3.5 (MF) 0.5 2.5 2 2.5 0.6 2.6 3 3.2 (MF) 0.5 2.7 3 .sup.1) 3.1 (MF) 0.4 2.6 4 3.2 (MF) 0.5 2.4 5 3.4 (MF) 0.5 2.5 6 1.8 0.5 2.3 7 .sup.2) 1.8 0.1 0.4 8 .sup.2) 0.5 0.3 0.1 .sup.1) after storage for 10 days at 50 C. .sup.2) comparative MF: fracture in material

TABLE-US-00002 TABLE 2 Effect of emulsifier on instantaneous adhesion Instantaneous adhesion Peel strength after Example [N/15 mm] 24 h [N/15 mm] 3 2.5 3.2 3 + 2.5 pphm Disponil FES 27 1.0 1.9 2 2.1 2.6 8 (comparative) 0.5 1.0

[0098] The results show that the copolymerization of oxazoline-containing monomers in an emulsion polymer stage after the neutralization of the acid monomers in the first stage produces a significant improvement in the peel strengths, even under thermal load and especially under the influence of aggressive media (after storage in ketchup, for example). The paucity of emulsifier endows the dispersions with excellent instantaneous adhesion (Table 2).