DE19535915A1 - Coupling agent for bonding plastic film with metal - Google Patents

Abstract

A coupling agent (I) for bonding plastic films with substrates contains (A) a grafted polypropylene random block copolymer; and (B) UV stabiliser(s). Also claimed are composites (MPC) contg. a metal base, layer(s) of (I) and layer(s) of plastic film, pref. polypropylene film.

Description

The present invention relates to an adhesion promoter for the connection of plastic films with substrates, preferably made of metal.

DE-OS 31 28 641 describes a process for the production described by laminates for food packaging, where the metal sheet and a thermoplastic Resin film along with one between these layers arranged adhesive based on a carboxyl group-containing polyolefin at temperatures heated above the melting point of the adhesive and then cooled together using pressure be what the metal-plastic composite will be produced.

Furthermore, from DE-OS 29 12 023, the GB-A 2027391 and EP-B 31701 laminates and from these Laminated food packaging containers, especially bags known.

The establishment of a sufficient adhesive bond in the bond between plastic coating and carrier comes central to the durability of the end material Meaning too. The one used for this Manufacturing process therefore ultimately determines which end product is obtained. According to the state most common in technology  Coating process is the application (laminating, Lamination) of a prefabricated plastic film. For a few special cases, however, the so-called Direct extrusion described, d. H. the application of plasticized plastic from an extruder directly on the support to be coated. So describes e.g. B. EP 0 038 075 the application of a Films made of polyethylene or polypropylene on one Carrier. This carrier has a complex structure several layers of material, the total thickness of one Multiple times the thickness of the plastic coating is.

EP 031 701 also describes the generation of a Plastic laminates in which one component, namely the adhesion promoter, applied by direct extrusion becomes. It is melted in between Carrier metal and plastic film given and through there Press rolls distributed.

The object of the present invention is plastics with substrates, preferably metal places that have improved adhesive properties. This job will be an adhesion promoter for the Compound of containing by an adhesion promoter, Maleic Anhydride Grafted Polypropylene Random Block copolymer and at least one UV stabilizer solved.

The polypropylene graft copolymers can be produced by grafting α, β-ethylenically unsaturated Carboxylic acids or their anhydrides, such as Maleic anhydride, on polypropylene in usual Mixers or extruders.  

The graft copolymers can be produced in this way be that the basic materials with peroxides implements or strong mechanical loads subject, thereby generating radicals and using them suitable monomers in contact. After this British Patent 679,562 can handle the radicals High-speed stirrer, shaking, grinding, kneading, Ultrasonic vibrations or passing filters or Capillary tubes with high linear speeds be generated. This causes the Polymers, whereby reactive radicals are formed where a graft reaction can take place.

Grafting can be carried out in conventional extruders be suitable if the reaction mixture Initiators such as organic peroxides and the Implementation in a z. B. in U.S. Patents 3,862,265, 39 53 655 and 40 01 172 described special Carries out reaction zone.

The radicals can be thermal, using high energy Radiation or mechanochemically, e.g. B. in Disk extruder, are generated.

DE-A 36 39 564 describes a peroxide-free process for the production of graft polymers of polyolefins described. This method is preferred for Production of the compounds in the invention used adhesion promoters. This peroxide-free process has the particular advantage that no unwanted degradation and Crosslinking reactions take place. Furthermore occurs no impairment of the  Polymers in color and smell, also increases Use of peroxides in the grafting reaction Adhesion of the materials obtained polar substances such as metals.

As α, β-ethylenically unsaturated carboxylic acids and / or their derivatives come in particular the usual ones Compounds such as maleic acid, fumaric acid, itaconic acid, Acrylic acid, acrylic anhydride, methacrylic acid, Crotonic acid, maleic anhydride, itaconic anhydride into consideration. Preferred compounds are maleic acid, Fumaric acid and especially maleic anhydride in Consideration.

The monomers to be grafted on are generally in the Concentration range of 0.01 to 0.5 wt .-%, based used on the polymer mixture. In general the monomers to be grafted on melted polymer mixture admixed, and the Grafting reaction is in the temperature range of about 200 ° C up to about 300 ° C in conventional extruders at one pressure from 1 to about 500 bar.

With ethylenically unsaturated carboxylic acids or Carboxylic anhydrides are grafted polypropylenes described for example in EP-A 385 645, US 4,957,820, US 4,980,210, EP-A 312 306 and EP-A 312302.

As base polypropylenes to be grafted on Polypropylene random copolymers or Polypropylene random block copolymers are suitable. So are among polypropylene random copolymers statistical copolymers of propylene with 1 to  to understand about 10 wt .-% comonomers. Suitable Comonomers are C₂ to C₁₂-, especially C₂- to C₆ monoolefins.

Under the so-called polypropylene random block copolymers are mixtures of polypropylene Copolymer and propylene comonomer rubber too understand. They consist of a polymer of 25 to 97 wt .-% of a propylene polymer (I), the 0.1 up to 15 wt .-% of copolymerized C₂-C₁₀-alk-1-enes contains and from 3 to 75 wt .-% of another Propylene polymer (II), the 15 to 80 wt .-% has polymerized C₂-C₁ Alk-alk-1-enes.

Among polypropylene random block copolymers are to understand copolymers, their matrix material consists of propylene random copolymer. From usual Polypropylene block copolymers, which as Have matrix material propylene homopolymer, the differ Propylene random block copolymers by higher Flexibility, toughness and better weldability.

Are particularly preferred in the invention Associated adhesion promoter used, one with 0.1 to 0.5% by weight, preferably 0.2 to 0.4% by weight, based on the total monomer weight, maleic anhydride grafted polypropylene random block copolymer contain.

Also preferred are adhesion promoters that have a 0.1 to 0.5% by weight, preferably 0.2 to 0.4% by weight, based on total monomer weight, Maleic anhydride grafted polypropylene  Random copolymer from 1 to 10% by weight, preferably 1 up to 7% by weight, based on the total monomer weight, Contain ethylene and / or C₄ to C₁₀ monoolefins. As examples of suitable C₄ to C₁₀ monoolefins are butene-1, 4-methylpentene-1, hexene-1, n-octene-1 and to call n-decen-1.

The graft polymers suitable as adhesion promoters can possibly be grafted together with Polypropylenes to be used. To be a good one Adhesion between the polypropylene top layer and the To reach metal, however, it is necessary that the Content of unsaturated carboxylic acid or its Derivatives is at least 0.05%.

Suitable polypropylenes and processes for their Production are, for example, in EP-A 312302 described.

Essential to the invention is the addition of substances to Stabilization against UV radiation. This will be preferably from amounts of 0.01 to 3, especially preferably from 0.02 to 2% by weight. Therefor for example, antioxidants come into consideration. Here can be very organic compounds act different construction, the unwanted, by changes in oxidative processes due to inhibit or prevent protective substances. Effective are especially those substances that are sterically hindering Groups included. These include, for example substituted phenols, hydrones, pyrocatechols and aromatic amines and their metal complexes.  

To further improve protection against UV radiation, special UV filter substances can be mixed in will. This is in particular: Compounds with high absorbency for UV radiation used as a sunscreen Improving the lightfastness of paints and Lacquers, plastics and rubbers, glasses and Packaging materials and other technical Products are known from the prior art. in the in general, these are derivatives of Benzophenones, their substituents, such as hydroxy and / or alkoxy groups mostly in two and / or four position. Furthermore are also substituted benzotriazoles suitable, furthermore in three Position, phenyl-substituted acrylates, possibly with Two-position cyano groups or salicylates.

The UV stabilizers described serve Surprisingly, not only improving the Protection against UV radiation. It is not one predictable finding that in the inventive Polypropylene Bonding Agent Metal Compounds That Adhesion is significantly improved in a way that was previously not achievable.

An example of a particularly good one according to the invention UV stabilizer that can be used is Chimassorb 944, too can be obtained from Ciba-Geigy.

The adhesion promoter according to the invention is suitable especially for connecting substrates made of metal with plastic films, preferably made of polypropylene. Accordingly, the subject of the present invention is also a metal bonding agent-plastic film composite that  from a carrier substrate made of metal, at least one Layer of an adhesion promoter with the above described composition and at least one Plastic film layer exists.

The composite material according to the invention consists consequently from the sequence of layers Polypropylene film adhesion promoter metal, being as Adhesion promoter that described with carboxyl groups and / or modified polypropylene is used.

To produce the polypropylene film, polypropylene random copolymers of 90 to 99% by weight, preferably 93 to 99% by weight, propylene and 1 to 10% by weight, preferably 1 to 7% by weight, of comonomers with a Molar mass distribution M _w : M _n in the range from 2 to 10, preferably 3 to 6, and a melt index MFI 230 ° C./2.16 kg in the range from 1 to 20 g / 10 min, preferably in the range from 4 to 15 g / 10 min. Likewise, for the production of the polypropylene film, polypropylene random copolymers of 1 to 4% by weight of ethylene and 99 to 96% by weight of propylene, based on the monomer weight, with a molecular weight distribution M _w : M _n in the range from 3 to 6 and a melt index MFI 230 ° C / 2.16 kg in the range of 5 to 9 g / 10 min can be used.

A further possibility is to produce polypropylene random copolymers from 90 to 97% by weight of propylene, 2 to 5% by weight of ethylene and 1 to 6% by weight of butene-1, in each case based on the total monomer weight, for producing the polypropylene film. with a molecular weight distribution M _w : M _n in the range from 3 to 6 and a melt index MFI 230 ° C / 2.16 kg in the range from 4 to 8 g / 10 min.

The polypropylene random block copolymers exist from a polymer of 25 to 97 wt .-% one Propylene polymer (I), the 0.1 to 15 wt .-% contains polymerized C₂-C₁₀-alk-1-enes and from 3 to 75% by weight of a further propylene polymer (II), the polymerized 15 to 80 wt .-% C₂-C₁₀- Alk-1-ene.

Comparable composites are in DE 42 29 419 describe, but without the invention Adhesion promoter layer.

To produce the coated according to the invention Sheet metal with a thickness of 0.04 is suitable up to 1 mm from black plate, tin plate, aluminum and various iron alloys, possibly with a Passivation layer based on nickel, chrome and Zinc compounds are provided.

The used as the top layer of the composites thermoplastic polypropylene can Polypropylene random copolymers also in the form of a Slide or a film. It can also be composite foils and films (composite foil and -films) that are preserved, for example by extruding different ones together Polypropylene random copolymers. Such Polypropylene films are made by known methods (Blowing process, chill-roll process, etc.) Granules made of polypropylene.  

According to the invention, for the production of the polypropylene films of the polypropylene film adhesion promoter-metal composites, statistical polypropylene copolymers are suitable which are obtained by statistical copolymerization of 90 to 99% by weight, preferably 93 to 99% by weight, propylene and 1 to 10% by weight .-%, preferably 1 to 7 wt .-%, each based on the total monomer weight, comonomers. The statistical copolymers have a molecular weight distribution M _w : M _n in the range from 2 to 10, preferably 3 to 6, and a melt index MFI 230 ° C./2.16 kg in the range from 1 to 20 g / 10 min, preferably in the range from 4 to 15 g / 10 min (measured according to DIN 53 735). Such polypropylenes and processes for their production are known. They can be produced, for example, by the polymerization process described in DE-A-37 30 022 using a Ziegler-Natta catalyst system. The propylene copolymers can be prepared, for example, in a gas phase polymerization process at from 20 to 160 ° C. and at a pressure from 1 to 100 bar. The molecular weights of the polymers can be regulated by generally known measures, for example by means of regulators, such as hydrogen.

Suitable comonomers are, for example, C₂- and C₄- to C₁₂ monoolefins, especially C₂ and C₄ bis C₆-monoolefins, such as ethene, butene-1, 4-methylpentene-1, Hexen-1, n-Octen-1, n-Decen-1 and n-Dodecen-1.

Polypropylene random copolymers of 1 to 4% by weight of ethylene and 99 to 96% by weight of propylene, each based on the total weight of the monomer composition, are to be mentioned as particularly suitable, the random copolymers having a molecular weight distribution M _w : M _n in the range from 3 to 6 and a melt index MFI 230 ° C / 2.16 kg in the range from 5 to 9 g / 10 min (measured according to DIN 53 735). These polypropylene copolymers have a melting range of approx. 135 to 155 ° C (determined by DSC). When using plastic films based on such polypropylenes, plastic film-metal laminates are obtained which have no whitening whatsoever.

Polypropylene random copolymers of 90 to 97% by weight of propylene, 2 to 5% by weight of ethylene and 1 to 6% by weight of butene-1, each based on the total weight of the monomers, have a molecular weight distribution M _w : M _n in the range from 3 to 6 and a melt index MFI 230 ° C / 2.16 kg in the range from 4 to 8 g / 10 min. Such polypropylene random copolymers have a melting range from 120 ° C to 145 ° C (determined by DSC). The plastic films that are available from these polypropylenes lead to plastic film-metal laminates, which also have no tendency to whitening.

All stated values for the melt index MFI refer to the measurement according to DIN 53735.

The polypropylene copolymers used to produce the plastic-metal composites according to the invention are available, for example, under the trade names Novolen ^R 3225 MCX and Novolen ^R 3520 LX from BASF AG.

Mixtures of the stated polypropylene copolymers, preferably 1: 1 mixtures, can of course also be extruded together to form a film. According to the present invention, the polypropylene random copolymer used to produce the polypropylene film can be replaced up to 50% by weight with polypropylene homopolymer. In this case, a mixture of random polypropylene copolymer and polypropylene homopolymer is extruded into a polypropylene film. If more than 50% by weight of polypropylene homopolymer is used in the plastic mixture, the metal-plastic laminates produced therefrom show a certain tendency to break. Suitable propylene homopolymers have a molecular weight distribution M _w : M _n in the range from 2 to 10, a melt index MFI 230 ° C./2.16 kg in the range from 1 to 20 g / 10 min (measured in accordance with DIN 53 735) and an isotaxy Index in the range of 80 to 99%, preferably 90 to 98%.

A mixture of the statistical polypropylene copolymer described and a polypropylene homopolymer with a molar mass distribution M _w : M _n in the range from 3 to 6 and a melt index MFI 230 ° C./2.16 kg in the range from 4 to 15 g / Used for 10 min (measured according to DIN 53735). The isotaxy index of these polypropylene homopolymers is in the range from 80 to 99%, preferably in the range from 90 to 98%. The homopolymers are known and can be prepared, for example, by the polymerization process described in DE-A 37 30 022.

Propylene homopolymers with a molar mass distribution M _w : M _n in the range from 3 to 5 and a melt index MFI 230 ° C./2.16 kg in the range from 10 to 12 g / 10 min (DIN 53 735) are particularly preferred.

Suitable propylene homopolymers are, for example available under the trade name Novolen® 1100 N and Novolen® 1125 N (BASF AG).

The described thermoplastic polypropylene Plastic films can also be conventional additives, such as. B. internal and external lubricants, antiblocking agents, Stabilizers, antioxidants, pigments, Contain crystallization aids and the like. These additives are used in manufacturing, Processing, packaging and application necessary quantities in the form of powder, powder, pearls or used directly incorporated into the polymer. More information on the amounts usually used and are examples of suitable additives for example the book Gächter-Müller, Plastic additives, Carl Hanser Verlag.

It is particularly advantageous if the thermoplastic Polypropylene films up to 0.5 wt .-%, based on the Total weight of the film, erucic acid amide and / or Oleic acid amide as a lubricant and up to 0.2% by weight, based on the total weight of the plastic film, Antiblocking agents, preferably silicon dioxide, and possibly antioxidants and possibly other Processing stabilizers included.  

Phenol derivatives are preferred as antioxidants used. Other suitable additives are titanium dioxide, Calcium carbonate, diatomaceous earth, calcium stearate as well primary and secondary fatty acid amides. As UV stabilizers, for example HALS-type UV stabilizers are used.

The metal adhesion promoter according to the invention Plastic film composite can be used for the Coating of various substrates used, e.g. B. of facades and roofs. Preferably they will molded and used for the purposes mentioned. Shaped parts can also be produced especially for the production of household appliances own, e.g. B. refrigerators, washing machines, stoves, etc.

The invention will now be described with reference to FIG the example described in more detail.

example PP coex film for coating coils example 1

100 parts by weight of a propylene-ethylene copolymer, consisting of 54.3% by weight of a statistical ethylene Propylene copolymer (determined by Extraction fractionation according to W. Holtrup, Makromol. Chem. 178, 2335 (1977)) with 2.5% by weight polymerized ethylene (determined by Fourier transform spectroscopy) and 45.7% by weight  of a propylene-ethylene copolymer with a Ethylene content of 60% by weight and a melt flow index of 1.0 g / 10 min (at 230 ° C and 2.16 kg, according to DIN 53735) were in a ZSK 40 twin-screw extruder 0.5 part by weight of maleic anhydride and 0.04 part by weight Share 2,5-dimethyl-2,5-di- (tert.butylperoxy) hexane 240 ° C reacted. After the reaction zone volatile components of the reaction were Vacuum degassing removed. The average Residence time in the extruder was 1.5 minutes.

Then 100 parts by weight of the thus obtained Product together with 0.5 part by weight of Chimassorb 94.4 on a ZSK 40 twin-screw extruder at 220 ° C extruded. The average residence time was 1.5 minutes. The product obtained is color and odorless.

Comparative Example A

100 parts by weight of that used in Example 1 MSA-modified ethylene-propylene copolymers were used under the same experimental conditions, but without Add Chimassorb 944 on a twin-screw extruder ZSK 40 extruded.

The melt index and the MSA content of the so obtained Products can be found in Table 1 below.

Claims (16)

1. Adhesion promoter for the connection of Plastic films with substrates, preferably made of Metal containing grafted polypropylene random Block copolymer and at least one UV stabilizer. 2. adhesion promoter according to claim 1, characterized, he a polypropylene random block copolymer ent holds that by grafting with α, β-ethylenic unsaturated carboxylic acids or their anhydrides, preferably maleic anhydride is available. 3. adhesion promoter according to one of claims 1 or 2 characterized in that he grafted polypropylene random copolymer from 1 up to 10% by weight, preferably 1 to 7% by weight on the total monomer weight, ethylene and / or Contains C₄ to C₁₀ monoolefins. 4. adhesion promoter according to one of claims 1 to 3, characterized in that he grafted with polypropylene random copolymer 0.1 to 0.5% by weight, preferably 0.2 to 0.4% by weight of α, β-ethylenically unsaturated carboxylic acids corresponding anhydrides or the corresponding Esters or half-esters with 1 to 8 coals contains atoms in the alcohol residue. 5. adhesion promoter according to one of claims 1 to 4, characterized in that he preferred as a UV stabilizer antioxidants  substituted phenols, hydroquinones, pyrocatechols and / or aromatic amines and / or their Contains metal complexes. 6. adhesion promoter according to one of claims 1 to 5, characterized in that that it is 0.01 to 3, preferably 0.02 to 2% by weight Contains UV stabilizer 7. adhesion promoter according to one of claims 1 to 6, characterized, he UV filter substances, preferably derivatives of benzophenone, substituted benzotriazoles and / or phenyl-substituted acrylates. 8. Metal bonding agent-plastic film composite, characterized in that he a carrier substrate made of metal, at least one Layer of an adhesion promoter according to one of the Claims 1 to 7 and at least one Plastic film, preferably made of Contains polypropylene. 9. Metal adhesion promoter-plastic film composite according to claim 8, characterized in that for the production of the polypropylene film polypropylene random copolymer, 90 to 99 wt .-%, preferably 93 to 99 wt .-%, propylene and 1 to 10 wt .-%, preferably 1 to 7 wt .-%, comonomers with a molecular weight distribution of M _w : M _n in the range from 2 to 10, preferably 3 to 6, and a melt index MFI 230 ° C / 2.16 kg in the range 1 to 20 g / 10 min, preferably in the range from 4 to 15 g / 10 min., Can be used. 10. Metal adhesion promoter-plastic film composite according to claim 9, characterized in that for the production of the polypropylene film polypropylene random copolymer 1 to 4 wt .-% ethylene and 99 to 96 wt .-% propylene, based on the total weight of monomers, with a molecular weight distribution of M _w : M _n in the range from 3 to 6 and a melt index MFI 230 ° C / 2.16 kg in the range from 5 to 9 g / 10 min can be used. 11. Metal adhesion promoter-plastic film composite according to claim 8, characterized in that for the production of the polypropylene film polypropylene random copolymers of 90 to 97 wt .-% propylene, 2 to 5 wt .-% ethylene and 1 to 6 wt. % Butene-1, in each case based on the total monomer weight, with a molar mass distribution of M _w : M _n in the range from 3 to 6, and a melt index MFI 230 ° C./2.16 kg in the range from 4 to 8 g / 10 min can be used. 12. Metal adhesion promoter-plastic film composite after Claim 7 characterized in that that for the production of the polypropylene film used polypropylene random copolymer 50% by weight has been replaced by polypropylene Homopolymer.   13. Metal adhesion promoter-plastic film composite according to claim 8, characterized in that the polypropylene homopolymer used has a molar mass distribution of M _w : M _n in the range from 3 to 6 and a melt index MFI 230 ° C / 2.16 kg in the range from 4 to 15 g / 10 min. 14. Metal bonding agent-plastic film composite after Claim 8 characterized in that the polypropylene film from 0.5 wt .-%, based on the total weight of the film erucic acid amide and / or Oleic acid amide as a lubricant and up to 0.2% by weight, based on the total weight of the Plastic film, anti-blocking agents, preferably Silicon oxide and possibly antioxidants and possibly other processing stabilizers. 15. Use of the adhesion promoter according to one of the Claims 1 to 7 for the connection of substrates, preferably made of metal with plastic films preferably made of polypropylene. 16. Use of the metal coupling agent Plastic film composite according to one of the claims 8 to 13 for the production of coatings, especially facade cladding, and of Molded parts, especially household appliances, roofs, Facades.