Adhesive peelable film

The present invention relates to a releasable adhesive film and a method for manufacturing such film.

The document WO-A-96/04 178 describes a peelable film comprising a core layer comprising an olefin polymer and goryacheskleivayuschiysya layer containing a mixture of low density polyethylene (LDPE) and a material that is incompatible with LDPE, such as an olefinic polymer or co- or terpolymer of ethylene propylene or butylene. The film structure may goryacheskleivatsya container of plastic for the lid of the container or herself for packaging.

The document EP-A-746 468 describes a multilayer film which is peeled by the destruction within what is called in the specification intermediate layer between the base layer and goryacheskleivayuschimsya layer. As indicated, the intermediate layer preferably comprises a blend of polymers that do not crystallize together.

U.S. Patent №5443915 discloses oriented polyolefin film comprising a matte white surface layer forming holodnoskleivanii at the receiving side, one side of the medial layer and a vapor-deposited metal layer on the other side of the medial layer.

U.S. Patent №5358792 describe goryacheskleivayuschuyusya composition comprising (a) from about 30 to about 70% (wt.) Of the low melting polymer comprising an ethylene copolymer of very low density, determined by the density in the range from about 0.88 g / cm3 to about 0.915 g / cm3, a melt index of about 1.5 dg / min to about 7.5 dg / min, a molecular weight distribution (Mw / Mn), not greater than about 3.5, and (b) from about 70 to 30% (wt.) of propylene-based polymer.

U.S. Patent №5482780 describe oriented α-olefin polymer film comprising: a core layer of an isotactic propylene homopolymer; a surface layer forming at holodnoskleivanii separated side and attached to one side of the central ply; and the treated layer on the surface, forming a receiving side when holodnoskleivanii, or subjected to a treatment layer comprising cohesive holodnoskleivayuschuyusya composition throughout the treated surface of said layer on the other side of the medial layer. Surface layer forming the detachable side when holodnoskleivanii comprises a slip agent, and a mixture of two polymers, namely, an ethylene-propylene random copolymer containing from about 2% to 8% of ethylene in such a copolymer, and an ethylene-butene copolymer, containing about from 0.5% to 6% of ethylene in a copolymer. Layer forming the receiving side when holodnoskleivanii is an ethylene-propylene random copolymer containing from about 2 to 8% ethylene.

U.S. Patent №5500265 described peelable film comprising (a) a core layer comprising an olefin polymer, (b) a surface layer on at least one surface of the medial layer, wherein the surface layer comprises: a mixture of butylene polymer with another olefin polymer, or a polymer of butylene and at least one other olefin, and (c) a coating layer on the surface layer.

U.S. Patent №5716698 relates to a releasable, oriented, opaque polyolefinic multilayered film comprising at least one opaque layer and peelable top layer.

U.S. Patent №6248442 relates to multilayer films which are goryacheskleivayuschimisya a wide temperature range. Patent '442 also refers to multilayer films, which provide for easy-open packaging and hermetic bonding. The films of Patent '442 are formed out of the middle layer containing linear low density polyethylene (LLDPE), and at least one surface layer having a melting point at least 10 ° C lower than the melting point of the medial layer.

U.S. Patent №5997968 discloses a multilayer polyolefin film comprising at least three co-extruded layers comprising an opaque base layer, an intermediate layer and an outer releasable surface layer consisting of two incompatible polyolefins, wherein the intermediate layer comprises at least 80 % (wt.) of the polyolefin having a lower melting point or glass transition temperature lower than the polyolefin, forming the base layer.

U.S. Patent №6231975 described ADHESIVE film comprising a core layer of any olefin polymer, an adhesive layer and a release layer located between them. Separation layer comprises an ethylene-propylene copolymer or blend of polyethylene and other olefin which forms incompatible composition or mixture.

The other type of providing peel adhesion is described in the patent application of the applicants 0514785.5 United Kingdom pending at the same time with this.

There is a constant need for improved products in the field of adhesive and peelable film structures. In particular, there is still a need for a film structure, which has an adhesive outer layer that glues well with themselves or other surfaces in a wide range of temperature and / or pressure, and which can peel off in the same layer of the multilayer film, and which nonetheless retains acceptable performance for the end use of the film in the embodiment with regard to at least one property selected from gloss, haze, opacity, suitable for use in printing and coefficient of friction. In particular, there is a need for peelable films which may be easily opened without forming a gap "direction z». When subjected to tension polyolefin films, in particular biaxially oriented polypropylene films, mechanical strength glue joints often exceeds the mechanical strength of the film itself, and therefore when the opening-glued packaging is not only disconnected seam gluing. Usually, at the opening of the gap it spreads uncontrollably throughout the film. Peelable film is a film which, when bonded, may again be mechanically separated without damaging or destroying the film itself. Peelable adhesive layers typically must be characterized by a good ability to stick together and to ensure a controlled opening of the package or packages. Peel goryacheskleivayuschayasya film may be formed in the preparation of a film coated by applying a coating on the biaxially oriented polypropylene film was prepared in the form of a multilayer film comprising a core layer of polypropylene homopolymer and a surface layer formed on each side or major surface of the medial layer, goryacheskleivayuschimsya coated . Such surface layers can be prepared from copolymers such as copolymers of propylene and ethylene, including a block copolymer. The surface layer produced during the manufacture of the film in the form of a coating from a melt, appeared to being applied as a coating provides a bonding providing delamination by the presence of a coating applied from a melt incompatible phases. This limits the destruction of the plane by the coating applied from a melt, removing it from the medial layer, which eliminates any possibility of break in the middle bonding layer. The result is that the bonding is weaker in comparison with conventional gluing, but allows for the same bonding strength in all possible locations, and does not result in tearing.

The gap in the z direction destroys the integrity of the multilayer film while stretching the film in different directions on the bonding portion. A film with a gap in the z direction is not simply divided by the glue line. Instead, the division or rupture and spread to the other layers of the film. Packaging which has undergone rupture in the direction z, it is difficult to re-seal properly, thus inhibits the ability of the package to preserve the freshness or the integrity of its contents. In the case of the possibility of excluding the gap in the z-direction packaging can be easily re-folded and glued by simple mechanical means such as a clip or an adhesive label.

The aim of the invention is to provide an adhesive polymer film, characterized by the ability to delaminate. Another object of the invention is to provide a thermoplastic film structure comprising an external adhesive layer that glues well in a wide temperature range. Further object of the invention is to provide a thermoplastic film structure comprising an external adhesive layer, which in the case of the bonding can be easy to open without a gap in the z direction. Further object of the invention is to provide such films for wrapping and provide peel adhesion in the packaging of articles or products.

It has now been found that the peelable adhesive films can be obtained in the form of a multilayer film, in which the block copolymer component is present in the middle layer. It seems that the film of the invention is peeled in the middle layer, although the invention described herein is not bound or limited by this theory.

Biaxially oriented films comprising a block copolymer middle layer, known in connection with several areas of application. For example, the document WO-A-2005/033195 describes high impact copolymer film showing the presence of certain characteristics of water vapor transmission rate, which is claimed to be suitable for use in applications in packaging of food products. Such films for such applications described in EP-A-0987290. Still other films for packaging foodstuffs utilizing the characteristics of a block copolymer film on the passage of gas and steam, described in document WO-A-2004/056 567. However, use of a block copolymer material in the middle layer of the multilayer film provided with an adhesive outer layer, which makes a releasable film bonded on the block copolymer middle layer, until the present time have not yet been realized.

In accordance with the present invention, a peel and adhesive film comprising a block copolymer substrate and an adhesive coating thereon and / or surface layer.

Film of the invention is preferably a multilayer film comprising a block copolymer core layer and at least one adhesive surface layer. The surface layer may be adhesive by nature, or it may be applied to the adhesive coating.

Preferably, the adhesive coating is applied to at least one surface layer.

The term "tacky" is meant goryacheskleivayuschiysya, holodnoskleivayuschiysya gummy molding or any suitable combination thereof. In most applications, be used goryacheskleivayuschiesya film.

The block copolymer substrate or core layer preferably comprise more than 90%, more preferably more than 95%, even more preferably more than 97.5% of the total film thickness.

In one embodiment, the core layer consists solely of the block copolymer substrate. In an alternative embodiment, the medial layer to obtain a block copolymer substrate may be mixed with one or more other suitable materials, provided that the core layer will retain its characteristics releasable.

The middle layer may be unfoamed or foamed may be desirable in the case of an opaque film.

Adhesive or peelable film structures of the present invention may also include one or more intermediate layers disposed between the middle layer comprising a releasable block copolymer substrate and an adhesive outer layer.

One advantage of the present adhesive and peelable films is the passage of delamination in the middle layer, which gives the manufacturer the freedom to adapt the surface layer (s) and / or intermediate layer (s) and / or coating (s) according to the production requirements, for example in respect of gloss, haze, opacity, suitable for use in printing, the coefficient of friction and the like.

The films of the invention will typically find themselves use in the packaging of articles of commerce, for example in the areas of application packages for the feet and packages for articles in the container.

In accordance with the present invention, a glued packaging obtained from a polymeric film comprising the block copolymer substrate and substrate-adhesive coating and / or surface layer, the package obtained by wrapping the film around the article to be packaged in such a way as to obtain at least one region of overlap of film and goryacheskleivaniya the resulting overlapping sections of the film with each other to obtain at least one glued packaging, the glued region substantially can be opened as a result of separation of the overlapping sections of the film by hand, which achieved without significant rupture film glued area or in its vicinity.

Without wishing to be bound by theory, one can say that the probability appears, giving a block copolymer desired releasable substrate as a result of allowing said film peeling goryacheskleennoy from its neighbor by overlapping in the form of delamination within the block copolymer medial layer film.

Preferably, the polymer film is a multilayer film comprising a block copolymer and a substrate, at least one surface layer of a different material. At least one surface layer may be a polymer material and may comprise a homopolymer and / or copolymer materials, or may be a mixture of two or more such materials. The surface layer may be formed on the substrate as a result of co-extrusion, lamination, or any other suitable method. Preferably, the surface layer is the product of co-extrusion. The surface layer can also be obtained from a peelable material such a block copolymer material. In an alternative embodiment, the surface layer may be neotslaivaemym and for example, may not include a block copolymer structure such as the structure of a random copolymer structure homopolymer or a suitable mixture of materials.

The presence of the surface layer can contribute to the realization of the invention in its more preferred aspects, as it will be possible to prevent or impede the spread of delamination initiated in the middle layer, such as between the two block copolymer components, beyond the medial layer. Propagation of delamination on the surface layers of the film may result in bursting of the film and the film does not peel.

Accordingly, the invention in one of its preferred aspects provides a glued container obtained from a polymeric film comprising the block copolymer substrate and of the substrate at least one surface layer, the surface layer is formed from an adhesive material or otherwise case it is applied adhesive coating, the package obtained by wrapping the film around the article to be packaged so as to obtain at least one area of ​​overlap of the film, and bonding the resulting overlapping sections of the film with each other to obtain at least one glued packaging, thus substantially glued area can be opened as a result of separation of the overlapping sections of the film by hand, which achieved without significant tearing of the film to the glued area or in its vicinity.

Preferably, the adhesive material and / or adhesive coating is goryacheskleivayuschiysya material, and overlapping film sections are glued to each other in a manner goryacheskleivaniya.

Preferably, the film used in the preparation of glued packages invention includes a block copolymer substrate, at least one surface layer and on the surface layer goryacheskleivayuscheesya coating.

In general, in order to facilitate the manufacture of the film will include a substrate in the form of a block copolymer medial layer, enclosed in a sandwich structure between the surface layers of the same material, the surface layers obtained on a substrate by co-extruding it, and goryacheskleivayuscheesya coating on one surface, preferably only on one surface of the resulting film.

Glued packing invention preferably obtained by cutting the sheet of polymeric film from the film web and cut the sheet wrapping plastic film around the product until the film tube with overlapping edges of the winding and gluing the overlapping edges to produce bonding, tight perimeter. Thereafter, the sleeve is preferably sealed at each end and bonded to receive the envelope or packet gluing.

One particular application of the film, and bonded packages invention is packaging for the feet.

Stops cut paper for copy machines, computers, printers, and other devices commonly packaged for transportation, storage and retail sale of packaging for the feet, made of various wrapping materials. These wrap materials traditionally consisted of paper, plastic film or film laminate of paper / plastic.

Wrapping materials protect the wrapped paper product from physical damage and moisture during transportation and storage. Wrapping materials also protect the wrapped product from physical damage during repeated handling and stocking the shelves at retail.

The allocation of reams of paper by moving boxes for larger users to feet wrapped for sale in individual packages containing, for example, 500 sheets. Such distribution of reams of paper making increasingly significant demands on the wrapper due to more frequent handling for individual feet. The increased number of handling operations to stop resulting in more frequent printing packages to stop damage to the wrapped paper product due to moisture, tear, or the appearance of a slight twisting of the paper - the physical damage that ultimately leads to zazhevyvaniyu printer paper or copier end user. However, emerging as a result of the ability of the package to avoid damage arising as a result of handling means and greater difficulties at the opening of the packaged product.

One way of eliminating this problem would be to have a means of bonding that would have mechanical strength sufficient to maintain adhesion intact during storage and transport until such time as the packaging or wrapper will need to be open, but the packaging will be suitable for opening by hand on site glueing or in its vicinity without incurring the risk of damaging the wrapped paper product.

The invention is particularly well suited for use in packaging technology to stop. Thus, in accordance with the invention a packing glued to stop, where the packaged product is a stack of paper.

The films of the invention are also particularly well suited for use in applications for packaging products in containers.

The block copolymer substrate preferably contains at least one olefin component. More preferably there is at least two olefinic component, wherein the block copolymer is at least partly prepared by block copolymerization of an olefinic component or a mixture of olefinic components with other olefinic component or a mixture of olefinic components. For example, the block copolymer substrate may comprise polypropylene and polyethylene.

Furthermore, the present invention provides a bonded package comprising the above respective polymer film coated on its surface layer, printed with at least one ink.

The film or surface layer of the film may also contain additional materials such as antiblock additives, opacifiers, fillers, UV absorbers, crosslinking agents, colorants, waxes, and the like.

The film of the invention may be further subjected to a corona treatment, for example, to further improve the ink absorbency to a film or surface layer of the film.

The substrate film may contain a mixture of block copolymer with the other substrate, a polymer material such as polyethylene, polypropylene, mixtures thereof, and / or other known polyolefins.

The polymer film can be prepared according to any method known in the art include, but are not limited to: obtaining a sheet of watering solution, the film obtained by extrusion through a slit die or the film obtained by extrusion blow molding. The invention may be particularly well suited for use in the case of films comprising a foamed or non-foamed polypropylene film comprising a core layer of block copolymer polypropylene / polyethylene and surface layers having a thickness substantially less than the thickness of the medial layer, and obtained, for example, random copolymers of ethylene and propylene or random terpolymers of propylene, ethylene and butylene. The film may comprise a film of biaxially oriented polypropylene (Dopp), which can be prepared in the form of biaxially oriented films, ravnorastyanutyh in both directions by using substantially the same draw ratio in longitudinal direction and the transverse direction, or they can be biaxially oriented film neravnorastyanutymi in both directions, wherein the film is significantly more orientated in one direction (longitudinal direction or transverse direction). Sequential stretching may be used, in which heated rollers carried stretching the film in the longitudinal direction, and then to realize the stretching in the transverse direction is used with the oven of the spreading frame. Alternatively, you can use the simultaneous stretching, for example, the use of so-called bag method or stretching on a tenter frame and simultaneously stretch.

The films used in accordance with the present invention may be characterized by a wide range of thicknesses according to the requirements in use. For example, they may have a thickness ranging from about 10 to about 240 microns and preferably a thickness of from about 50 to about 90 microns.

In the inventive multilayer film, comprising at least a substrate layer and a surface layer, the surface layer is preferably suitable for use in printing inks. The surface layer has a thickness ranging from about 0.05 microns to about 2 microns, preferably from about 0.1 microns to about 1.5 microns, more preferably from about 0.2 microns to about 1.25 microns, most preferably from about 0.3 microns to about 0.9 microns.

The invention will now be more particularly described by reference to the following examples.

EXAMPLE 1

Preparation of films

Three-layer polymeric sleeve is prepared by coextruding the medial layer (of polypropylene homopolymer of Comparative Example and polypropylene-polyethylene block copolymer in Example according to the invention), a layer of a terpolymer of polyethylene / polypropylene / polybutylene (random copolymer) as a surface layer on one medial side layer and a mixture of polypropylene random copolymer / polyethylene, polypropylene / polybutylene as a lamination layer on the other side of the medial layer. The sleeve is cooled and then reheated prior to inflating to obtain a three-layer biaxially oriented film tube. Thereafter, film sleeve compresses and laminated to obtain a laminated film consisting of an inner lamination layer having a thickness of about 0.7 .mu.m, the core layer having a thickness in the range of about 28 to 29 microns on both sides of the lamination layer and the surface layer of a random terpolymer with thickness of approximately 0.3 microns.

Thereafter, the laminated film was applied as a primer polyethyleneimine primer and one of its side - acrylic coating. The composition of the acrylic coating is in the form of a production lot for use as a source of an acrylic resin material present in the coating WB1240. WB1240 is a dispersion of an acrylic copolymer in water, supplied by UCB Surface Specialties, located at Rue d'Anderlecht 33 B-1620 Drogenbos Belgium, and the amount used is that which was necessary to obtain the coating film having a composition which was WB1240 92.5% (wt.) of the total coating. The coating composition also included 0.25% (wt.), Polymethyl methacrylate particles as anti-blocking agent and 7.5% (wt.) Of carnauba wax.

Compositions laminated uncoated films are given in Table 1:

Table 1PlenkaSeredinny sloyVnutrenny sloyVneshny sloyPrimer 1Blok copolymer (PP / PE) laminating resin (a mixture of PE / PP, PP / PB) random terpolymer (PP / PE / PB) Comparative Example 1aGomopolimer (PP) laminating resin (a mixture of PE / PP, PP / PB) random terpolymer (PP / PE / PB)

Both films have demonstrated the satisfactory performance in applications packages for the feet, as evidenced by measuring their gloss, haze when viewed at high and low angles, the adhesion in the middle, the adhesion on the side of sticking and friction coefficient, all of which were conducted according to standard procedures .

Thereafter, the coated film was subjected goryacheskleivaniyu at their foot wrap paper to obtain a glued packing stack. According to the comparative example obtained by bonding film is discontinuous and in the example illustrating the invention - delamination.