DE10353956A1 - Polymer (especially polyolefin) films or sheets with glycidyl-containing surface groups are surface treated to increase the surface tension and give a layer of high polarity - Google Patents

Abstract

A co-extruded film or sheet consists of a layer (1) of a polymer having C-C single bonds and a polymer layer (2) containing epoxide (glycidyl) groups, layer (2) being treated by a chemical or energy process to increase the surface tension and give a layer (3) of high polarity, this surface treatment not being applied to the other surface of (1), this other surface being bonded with any other layers. An independent claim is also included for a monolayer film or sheet in which a layer of a polymer having C-C single bonds and an epoxide (glycidyl) group-containing surface is treated by a chemical or energy process to increase the surface tension and give a layer of high polarity.

Description

The The invention relates to a process for producing an extruded Layer or film of polyolefins with increased surface tension, in which the surface opposite the usual stable C-C single bonds of carbon with new shares the epoxy groups, here a glycidyl or a glycidyl methacrylate, which is achieved with less energy than that which for breaking up the stable C-C single bonds is required. The penetration of the irradiation through the polyolefin layer or a measurable on the opposite side Value at increased surface tension is excluded because of the inclusion of the energy of these groups. Upon irradiation by corona of glycidyl deposits on the surface on another oxygen atom, it forms radicals, free valences, on which the anchoring of the layer to be applied takes place. The molecular chains the epoxy groups are firmly anchored in those of the polyolefin; thereby is an otherwise unachievable high anchoring aufzutragender Layers possible. A surface tension in mN / m or dyn / cm on a polyethylene film with the proportions the epoxy group of 46 dyn and higher is possible without the after The known harmful to coiling Blocking of the films occurs. A surface tension of more than 46 dyn / cm is the requirement for the anchoring of many adhesives. The foil consists of a Layer (1) of polyolefins as a support for the in the thin layer (2) epoxy groups incorporated from polyolefins, here a glycidyl and optionally a proportion of methacrylates which are resistant to COOH, OH, NH2 and similar Groups react a high.

Background of the invention

The now extruded polyolefins of polyethylene or polypropylene have from their natural Feature a low polar surface for anchoring other layers; the value of polyethylene is 30-32 dyn / cm, with added other polymers such as vinyl acetate partly until at most 35 dynes / cm; the value of polypropylene is 29-33 dynes / cm and thus even lower polar than that of polyethylene. For Anchoring on polyolefins is a high-energy irradiation for the Breaking the carbon C-C single bonds, preferably by means Corona, the usual one Method. The values measured immediately after production 44-46 dyn / cm are the upper limit because beyond that on the roll coiled foil locks or the irradiation on the other surface side the foil breaks through and this other surface in their functional properties for the use of the film to the uttermost Uselessness diminishes. The value achieved during irradiation the surface tension falls fast at 2-4 dyn / cm and can be later again by energetic irradiation - it is a cleaning of surface the substances accumulated and deposited there are refreshed. A reason for the Fall of the surface tension is the migration of short molecular chains from the polyolefin through the irradiated surface, so that through this Effect superimposed on the surface tension created by corona is or closes again. For the Anchoring individual adhesives is a real surface tension from 45 dyn / cm, partly up to 48 dyn / cm the requirement; these high Values are still not possible on films made of polyolefins, so that the Adhesion of the adhesive on the other higher polar surface than that of the wearer of the glue at the later Use of a film coated with adhesives occurs; the glue dissolves from the film of the polyolefin and remains on the other higher polar surface z. B. a metal, which is only with extremely high cost of the adhesive to clean again.

epiphany the invention

One Granules of low density polyethylene with proportions of 8% or 12% of glycidyl is on a hot plate when exposed to Air has been melted and formed a mass similar to one thin Plate or a thin one wide ring. The surface this mass was in proportion Very rough to polyethylene and showed the usual for the surface tension Test inks depending on the proportion of glycidyl in polyethylene a value at least 12 dynes / cm, some 16 dynes / cm above that of the unfilled natural one Polyethylene is. This effect of a co-polyolefin of ethylene with shares of glycidyl from the epoxy groups is not yet known. Polyethylene remains smooth and changed by this simple Process its surface tension Not.

Becomes the same co-polymer of ethylene and glycidyl with a second Layer of a polyethylene containing no other shares to one Foil to the exclusion of Oxygen coextruded, is only by irradiation, preferably by corona treatment the higher polarity reach the layer as only one layer of a polyolefin. Those with a dose of 0.56 amps at a withdrawal speed from 12 m / min. Corona treated surface of the co-polymer film Ethylene and 12% levels of glycidyl are polar in nature of glycidyl harsh, yes almost grainy. The values for the withdrawal speed and the dose of irradiation are dependent on the performance of the film production plant freely selectable adjustable.

The epoxide group is a cyclic ether with three ring atoms. The bond angles in the 3-ring are strongly distorted, so that the ring is under tension. Reaction with various substances opens the ring, creating a new atomic grouping with stress-free bonds. Due to the different electronegativities of carbon and oxygen, the epoxide group is polarized. The oxygen carries a negative partial charge and the carbon atoms positive partial charges.

1 shows epoxy and glycidyl as a group.

Most of the epoxy group is present as glycidyl ether. 2 ,

By one-sided substitution carry the carbon atoms of the epoxide ring different positive partial charge. This charge distribution causes that at the addition of compounds with a mobile H atom (acidic H atoms) to the epoxide ring runs a clear reaction.

Of the Epoxy oxygen at carbon atom-2 of the epoxy resin, whereas the additive component attaches terminally.

The epoxide group of epoxy and glycidyl used for the essential part of the invention shows 1 , It reacts mainly with the carboxy groups COOH, the hydroxyl groups OH and the amino groups NH2 ...

Alternatively, a compound of ethylene, acrylic ester, glycidyl with methacrylate can be used. 3 , Or only the part of ethylene, glycidyl with methacrylates or a propylene with glycidyl or a propylene with glycidyl with methacrylates.

Achieving the glycidyl groups requires much less energy than breaking the stable C-C single bonds of the polyolefin. In the irradiation with conventional methods such. B. Corona attaches to the glycidyl compounds to another oxygen atom, it forms radicals, known as free valencies, for the function of a highly bond-friendly layer for the absorption of coatings, which excludes simultaneously blocking the wound on a roll film. This achieved by irradiation extremely high binding friendly in the thickness not measurable surface as a layer (3) of the epoxy groups, here the glycidyl or glycidyl and methacrylates, referred to as GMA, is the invention. The layer (3) is only the chemical change of the surface of the layer (2). 4 ,

The layer (2) may also consist of a single layer of polyolefins with the added proportions of the epoxy groups, here the glycidyl or glycidyl with methacrylates, for. As a film, an extruded or molded part. 5 ,

Alternatively, the layers (1), (2) and (3) on the other surface of the layer (1) can still be connected to additional layers (A1), (A2), (A3) and further layers. 6 ,

On the active polarization of the surface that has become energetic due to the energetic treatment of the surface Epoxy groups consisting of glycidyl and optionally methacrylates, Layer (2) is the actual anchorage to apply Layer. An over or Infiltration by migrating macromolecule chains from the nonpolar polyolefin or there added waxy substances such as lubricants, process aids as stearates of optionally added colored polymers is excluded, because the molecular chains the epoxide group in the molecular chains firmly embedded or anchored to the waxy layer of the polyolefin are.

The macromolecular chains of the polyolefin move in the area of processing as a film and in their subsequent storage, because the temperatures change permanently and this change triggers the movement of the "living" polyolefin. The amorphous portion in the polyethylene is soft at -70 ° C, the crystalline portion only at 120 ° C; the difference is 190 ° C. The determined by standard molecular weights in the polymer are always only average values; there are higher and lower molecular weights within the mass of the extruded polyolefin; therefore, individual macromolecule chains of the polyolefin can migrate to the surface. Known is the migration of macromolecule chains due to lower density and the migration of added fatty substances such as lubricants, stearates, etc. on the surface of the film; as well as the stress relaxation of the macromolecules after their extrusion or after the last higher heat treatment also triggers a movement as well as the variations in temperature during storage of the plastic. The movement in the range of -70 ° C and higher easily leads to infiltration or to cover the treated with corona layer, so that months form completely sub-or migrated zones after the coating. The degradation of the surface tension takes place in a size of 2 to max. 4 dyn / cm immediately after the first treatment to increase the surface tension, preferably with corona. For adhesive coated surfaces of polyolefins, the adhesive visibly peels off when the other bonded surface has a higher polarity than that of the remaining layer (1) of the polyolefin. The later increase of the originally achieved surface tension by energetic treatment of the polyolefin before coating is ineffective from the beginning. The much lower Surface tension is excluded in the new film because of the properties of layer (2).

The surface tension the layer (2) can be with energetic oxidation or chemical Processes increased become. An energetic treatment of the layer (2) can by means of Corona, flame or plasma done. For three-dimensional parts can the treatment of the layer (2) by plasma or chemical Treatment with fluorine, here fluorine-containing gas mixtures of z. B. Fluorine and nitrogen with the exclusion of oxygen as fluorination or with oxygen as Oxydfluorierung done. Fluorine is that most reactive element which compounds with polymers received. Alternatively, chemical pickling with acid is possible. The most common Process is that of treatment with corona and polypropylene films in a few applications even more the flame.

A energetically treated surface a polyolefin remains smooth after treatment. The layer (2) with the epoxide groups of glycidyl is through the energetic Treatment with corona rough, sometimes slightly grainy. This is new and proves the chemical change through the surface the treatment to increase the surface tension, here a treatment with Corona.

It is known state of knowledge that the surface tension a layer of polyolefin just immediately after extrusion even before winding the film on the roll by means of energetic Treatment is achievable. The further experiments have the polar Behavior of epoxide groups with glycidyl show:

• Example 1:

The Layer (2) of a low-density polyethylene and 8% by weight of glycidyl is, according to known knowledge, immediately after Extrusion and before winding with an energetic treatment treated by corona. The energy used was 0.36 to 0.36 amps at a take-off speed of 12 m / min. The was found surface tension 44 dynes / cm. The same film is on the layer (2) 12 days after the extrusion with the energy of 0.82-0.84 amps at the same Withdrawal speed of 12 m / min. aftertreated. The on Surface tension measured at this layer (2) was 4 dynes / cm higher than the original value. The high value achieved in the second treatment is stable from the 2nd day for the Duration of further 14 days confirmed by re-measurement. That is new.

• Example 2:

A In the extrusion, energetically untreated layer (2) of polyethylene low density and containing 8% by weight of glycidyl after production a surface tension of 32 dynes / cm. It is 12 days later with the energy of 0.82-0.84 amps at the withdrawal speed of 12 m / min. treated with corona. It is a surface tension 42 dynes / cm had been measured; another 14 days later Storage of the film in the air are measured 38 dynes / cm very safe Service. Such a result is not yet possible because the stable C-C single bonds of the polyolefin only immediately broken after the extrusion and before the first winding of a film can be. So far the principle has been: After the extrusion of a polyolefin is the surface tension not increase anymore. The measurement of a surface tension from additionally at least 5 dynes / cm is the most valuable result of the invention, because the extrusion was done 13 days before the pretreatment.

• Example 3:

The Layer (2) of low density polyethylene with 12% parts by weight of glycidyl and additionally Colored yellow containing high-migrating stearates added thereto, is to known knowledge immediately after the extrusion and before 5 winding with an energetic treatment by means of corona been treated. The one for it The energy consumed was 0.54 to 0.56 amps at one take-off speed from 12 m / min. The surface tension found was 44 dynes / cm. All later Measurements confirmed the value of 42 dynes / cm, so even 20 days after the extrusion. One yourself later no longer changing or changed only insignificantly Value of the surface tension is new and is according to past experience as not possible.

• Example 4:

The layer (2) containing 12% by weight of glycidyl and additionally colored yellow with thereby added highly migrating stearates, has been treated by known knowledge immediately after the extrusion and before winding with an energetic treatment by means of corona. The energy used for this was 0.54 to 0.56 ampere at a take-off speed of 12 m / min. This layer is 23 days later a second time by corona at 1.35-1.50 amps and 13 m / min. Discharge speed has been treated. The surface tension found immediately after the 2nd treatment was at least 54 dynes / cm. A test with test ink 3 days later still showed a value of safe 48 dyn / cm, which was found in Be rich 46 dynes / cm to 48 dynes / cm confirmed 14 days later by measurement as stable. The other untreated low density polyethylene surface immediately after the second treatment showed the natural surface tension value of 32 dynes / cm; the value of 34 dynes / cm was clearly not reached. The otherwise known at such high dosage of energy in a treatment by corona and feared penetration of the treatment on the opposite side has failed. The layer (2) with the epoxy groups must have absorbed this enormously high energy and thus avoided the otherwise expected strike through.

All Measurements were made with a new test ink according to DIN 53 364.

These Measurements prove that for reaching Of the epoxy groups, here the glycidyl, much less energy is required as for breaking the stable C-C single bonds the polyolefin; The Epoxy groups may days later, probably Years later be achieved by irradiation after extrusion or it is known methods for increasing the surface tension effective. The timing of creating a for the anchorage of paints etc. safe surface is thus flexibly selectable, without the risks of the otherwise known degradation of the surface tension by migrating portions of the polyolefin through the corona treated surface.

With a later one second treatment of the surface by preferably corona the weeks later made by the impurities from the inside of the film the surface migrated short-chain molecules or molecules attached from above, which deposit above the corona treated surface and partially cover it, again immediately cleaned during coating or removed as So far, just a lot safer and optionally, a higher surface tension as at the original be adjusted extruded film. The processing will be very much safer and closes previous risks.

On a 2-layer film with the support of the layer (1) made of polyethylene the density of 0.930 without lubricant and the layer (2) with glycidyl linear low density polyethylene containing a surface tension of 44 dynes / cm. The slides settled 3 days after extrusion and degradation of the relaxation of the macromolecule chains without the lowest value of otherwise at such high levels of irradiation handle known blocking. The original value of the surface tension of 44 dyn is almost proven again by means of a test ink Service. This first experiment has proved that a significantly higher surface tension than those otherwise possible on polyolefins 44 to 46 dyn with the in the layer (2) containing attainable is and this value can be increased even without otherwise in the treatment triggering with Corona entering blocking of the polyolefin films. Further is still a longer time Obtaining the corona treatment has been demonstrated.

The secure anchoring of solvent-containing Dispersions of acrylates or solvent-free molten Acrylic adhesives require a surface tension of at least 45 dyn / cm, preferably a higher one Value. Also, a film produced by this method from polyolefins, here an oriented polypropylene, contrary the otherwise longtime Practice of 6 months, sometimes only 3 months, will be significantly extended and thus the trading practices and more recent legislation for the warranty of other products to adjust.

The typical applications of a film consisting of the layers (1) as a carrier and the layer (2) with the proportions of glycidyl, optionally with low levels of methacrylates, are:

Application 1:

 films made of polyethylene for the lamination with other films. The advantage is very much longer Durability of surface tension with the value of 38 dyn / cm. As an adhesive for lamination, isocyanate and aliphatic based adhesives used with the epoxy groups higher than react with those of the polyolefin and thereby the adhesion of the Improve the adhesive on the layer (2).

Application 2:

films made of polyethylene for the coating with acrylate adhesives, either as a dispersion applied by a system of rolls or as a hot melt from a slot die become. The advantage is the very high surface tension of 46 dyne / cm or 48 dyn / cm, which for the anchoring of the glue is an indispensable condition. To The performance at the coating plant is no longer due to the chemical properties of the film determined; the power can be used higher become.

Application 3:

oriented and non-oriented polypropylene films for printing or application laminating adhesives requiring a safe value of 38 dyne / cm - and higher.

Application 4:

oriented Polypropylene films for the coating with acrylate adhesives, either as a dispersion or as hot Melt from a slot nozzle be applied. The demanded very high surface tension with 46 dyn / cm or 48 dyn / cm for the anchorage of the glue is certainly fulfilled. Find such adhesive tapes as a packing tape or adhesive film general use. This is the performance at the coating plant no longer by the chemical properties the film determined; the performance can be used higher.

Application 5

The Anchoring a metallization on films of polypropylene applies because of the high nonpolar portions of the polypropylene as difficult. Therefore, coatings are done before metallization and these do not reach the optimal anchorage. This is confirmed no later than in sealing at least one metallized layer with a non-metallized layer, so that the strength of the seam through the Lack of adhesion of the metallization only a low strength reached. The applied layer of the metallization dissolves and connects to the sealed opposite side. The largest application of metallized Films on polyolefins are those on an oriented film, preferably biaxially oriented.

Application 6:

foil made of polyethylene or polypropylene, optionally oriented, for labeling by means of a ballpoint pen or similar tool. Will be like that a caption on an original with 38 dyn / cm surface treatment equipped Made of foil, it can easily be wiped off with a finger become. The applied on the layer (2) font by means of a Pen is only with solvents Completely from the surface to remove; she can not be wiped anymore.

Application 7:

A extruded fiber of a polyolefin, preferably a polypropylene, the for the connection with other layers z. B. later printing or gluing a higher one surface tension needs can either be coextruded from layers (1) and (2) or produced as a compound 1-layer, the surface tension of the Layer (3) optionally later be increased during further processing by energetic irradiation can, without diminishing the mechanical properties of the fiber. A fiber behaves in terms of blocking similar to a film; occurs a high Adhesion or even a bonding of the fibers to one another, can these are no longer deducted from the coil.

Application 8:

extruded Polyolefin pipes, depending on the application, made of polyethylene or polypropylene or even several layers, one of which is a layer of polyethylene and another layer of polypropylene may be preferred on the outer surface with to equip the layer (2), so that on it safer other substances to be anchored can be applied. The could be a caption.

Application 9:

In the injection molding process extruded plastic parts of polyolefin plastomers or polyolefin elastomers, optionally combined with other plastics by compounding, for use as, for. As bumpers or bumpers are made in the automotive industry, because these days or weeks to be painted after the extrusion of the polymer. These plastics can optionally be additionally crosslinked. Compounds of plastics are now used whose individual polymers have polar properties and which are treated by plasma coating for the anchoring of the paint. When these molded parts are provided with a very thin layer (2), elastic parts are available which can be painted after a surface tension-increasing treatment. Alternatively, the part may consist of a compound that the chemistry of the layer (2) and 5 equivalent.

Application 10:

blown hollow body of polyolefins, depending on the application of polyethylene or polypropylene or also several layers, one of which is a layer of polyethylene and another layer of polypropylene may be preferred on the outer surface with to equip the layer (2), so that on it safe adhesive labels and other materials to be anchored applied can be. Or it may be on the blown hollow bodies a film with the layer (2) and there applied adhesives higher than previously anchored.

A further advantageous combination with the epoxide group of the layer (2) is the added terpolymer of acrylic ester and anhydrite or acrylic ester and Malaissäureanhydrit in the polyolefin, preferably a polyethylene. Carboxylic acids also react relatively rapidly with epoxide groups because of their strongly polarized OH bond. Carboxyl groups are able to accelerate reactions of the epoxide group catalytically. Reaction of the acid anhydride with alcohol produces a free carbon acid group and an ester group. While the acid anhydride group itself does not react with an epoxide ring, the reaction of the anhydrite with a hydroxyl group of the epoxy resin gives rise to a carboxyl group, which in turn reacts with the epoxide ring as a new functional group. The polarity of the layer (2) is increased with the treatment described here for higher polarity, so that layers deposited there achieve a higher adhesion. Preferably, a second treatment of the layer (2) takes place energetically or chemically directly before the application of a further layer z. B. that of an adhesive. The immediate supply of heat in the range of 100 ° C and higher increases the anchoring of the applied layer.

The found new chemistry with the added proportions of epoxide groups in the layer (2) creates the possibility Days or weeks after extrusion, further irradiation to improve surface tension successfully perform to be able to; their additional Value is dependent from the height the spent energy. The value of the surface tension compared to first energetic treatment can be at about twice as high Dosing the energy with additional 6 dynes / cm to 8 dynes / cm. This high value is essential.

The in the applications 8 to 10 listed products can with even higher polarity be prepared because the risk of blocking a film or train does not exist. Many described applications show the broad use of this invention, which presumably now not yet foreseen benefits.

Claims (21)

A coextruded layer or film consisting at least from the layer (1) of a polymer with C-C single bond and a layer (2) with proportions in the polymers of the epoxy groups, here a glycidyl, whose layer (2) for achieving a higher surface tension treated by a chemical or energetic process and thereby achieving a layer (3) of high polarity and this treatment not on the other surface the layer (1) has become effective. The layer (1) can on the other surface be associated with other layers of your choice. A 1-ply layer or film of a polymer with C-C single bond, the surface of which polymers with the polymers of the epoxy groups, here a glycidyl shows and these for reaching a higher one surface tension treated by a chemical or energetic process and thereby reaches a layer (3) of high polarity at its surface is. A co-extruded layer or film according to claims 1 and 2, characterized in that the Polymers of the epoxy groups, here a glycidyl, still a methacrylate is added. Layer or film according to claims 1 to 3, characterized that in the layer (2) of the polymer incorporates the proportions of epoxide groups are that at least an atom of the epoxide group of glycidyl on the surface of the layer (2) is. Layer or film according to claims 1 to 4, characterized that in the layer (2) of the polymers nor shares of glycidyl and methacrylates so are incorporated that at least one atom of the epoxide group of glycidyl and an additional one Methacrylate group on the surface the layer (2) is. Layer or film according to claims 1 to 5, that the thickness the macromolecule chains of glycidyl incorporated in the layer (2) at least the thickness of a macromolecule chain reached. Layer or film according to claims 1 to 6, characterized that the Layer (1) consists of the polyolefin of an ethylene. Layer or film according to claims 1 to 6, characterized that the Layer (1) of the polyolefin of a propylene, consists. Layer or film according to claim 8, characterized in that that the Layer (1) of the polyolefin of a co-propylene exists. Layer or film according to claims 1 to 7, characterized in that for the layer (2) as a carrier a polyolefin of ethylene with a density of 0.915-0.966 or an olefin with a density of less than 0.89 is used. Layer or film according to claims 1-6 and 8-9, characterized characterized in that for layer (2) as a carrier a polyolefin of polypropylene is used. Layer or film according to claims 1 to 6 and 8, 9, 10 and 11, characterized in that for the layer (2) as a carrier a polyolefin of copolymer of ethylene and propylene is used. Layer or film according to claims 1 to 12, characterized in that the Polymers at their interfaces the layers (1) and (2) are no longer separable from each other. Layer or film according to claims 1 to 13, characterized in that the treatment for increasing the originally achieved surface tension in a second treatment is carried out energetically by means of corona. Layer or film according to claims 1 to 13, characterized in that the Treatment to heighten the original one reached surface tension in a second treatment is energetically by means of flame treatment is. Layer or film according to claims 1 to 13, characterized in that the Treatment to heighten the surface tension is done energetically by plasma. Layer or film according to claims 1 to 13, characterized in that the Treatment to heighten the surface tension chemically by means of fluorine and nitrogen with the exclusion of oxygen is done. Layer or film according to claims 1 to 13, characterized in that the Treatment to heighten the surface tension chemically with fluorine in the presence of oxygen as fluorination takes place, which is referred to as Oxifluorierung. Layer or film according to claims 1 to 18, characterized in that the Foil without energetic treatment of the layer (2) is extruded and the energetic treatment takes place later and thereby one Anchoring of other layers on the surface of the layer (2) is possible. Layer or film according to claims 1 to 19, characterized in that the Layer (1) with other layers by lamination, melting or Coextrusion is connected and the layers (2) and (3) the other outer surface for anchoring form another layer. Layer or film according to claims 1 to 20, characterized in that the Layer (2) in addition a terpolymer of acrylic ester and anhydrite or acrylic ester and maleate anhydrite in the polyolefin.