Method for labeling plastic bottles produced by blow molding

Abstract

The invention relates to a method for labeling PE, PET or PP bottles produced by blow molding, onto which bottles a PE label is glued after the bottles are filled, wherein the PE label located on a carrier is deflected by 180°, thereby releasing the PE label from the surface of the carrier, and is glued onto the passing PE, PET or PP bottle. According to the invention, the following are used: a PE label having a thickness of 100 µm to 150 µm, a carrier consisting of glassine having a thickness of 62 g / m2 to 90 g / m2 or a plastic film as the release carrier and, as the adhesive, an acrylate which has been applied to the underside of the label.

Description

[0001] Method for labelling blow-moulded plastic bottles

[0002] The invention relates to a method for labelling PE, PET or PP bottles produced by blow moulding, to which a PE label is affixed after filling, wherein the PE label arranged on a carrier is detached from the surface of the carrier by a 180° deflection and affixed to the PE, PET or PP bottle being conveyed past.

[0003] Blow molding is a process for producing hollow bodies from thermoplastics. In this process, a preform is subjected to internal pressure and is pressed against the contours of a blow mold, whereby it takes on the desired shape. Blow molding is a type of injection molding process and is very important in the production of bottles, containers and other hollow plastic bodies that are filled with liquid products. The process is characterized primarily by the fact that the manufactured parts have comparatively thin walls, which keeps material consumption and costs low. The plastic containers, in particular plastic bottles, are filled with the liquid such as a washing lotion, liquid cleaner or similar either immediately after blow molding or after intermediate storage, sealed and finally labeled.While the plastic containers are still relatively soft immediately after blow molding, they undergo a hardening process after intermediate storage or transport. The plastic containers removed from a storage reservoir for filling and labeling can therefore have varying degrees of stiffness depending on the degree of hardening.

[0004] The advantage of using labels over printing on containers or bottles is that the label can be separated from the container or bottle during a later recycling process, allowing high-purity plastic to be recycled without the printing ink causing contamination. In addition to paper labels, which are generally less scratch- and impact-resistant, plastic labels have become popular. These are attached to the bottle or container using an adhesive. A common process involves applying a layer of pressure-sensitive adhesive to the back of a layer of face- or butt-face material for the label, which is then covered with a release liner or carrier.This release liner or carrier protects the adhesive during shipping and storage and allows for efficient handling of an array of individual labels after the labels have been die-cut and the matrix has been peeled from the facestock layer until the individual labels are sequentially dispensed onto a labeling machine. From die-cutting to dispensing, the release liner or carrier remains uncut and can be used for storage, transit, and use of the array of ejected individual labels, rolled or unrolled, or unrolled as stackable goods.

[0005] In many labeling applications it is desired that the butt side material is a film made of a polymer material, in particular polyethylene, which, unlike paper, can be provided in a transparent, more durable, stronger, water-resistant, abrasion-resistant and with a gloss finish. For visual reasons, aesthetic designs are often chosen in which the label has irregular shapes rather than straight butt sides. As a rule, PE labels with a thickness of 50 to 70 μm are used to limit material costs. However, it is not uncommon for the label to fail to be reliably detached from the carrier using a peel-off plate, so that the label is sometimes not transferred to the plastic bottle without creases or, in isolated cases, even builds up so much on the peel-off plate that the entire labeling system has to be shut down.

[0006] Such problems arise in particular when adhesive residues remain on the edge area when cutting the label shapes, which prevent the label from being removed cleanly from the carrier.

[0007] It is therefore an object of the present invention to provide a method which avoids the aforementioned disadvantages and in particular allows a wrinkle-free, continuous operation at high machine speeds.

[0008] According to the prior art, it is known to adhere a plastic film to a carrier material, which film has usually been previously printed on the front and / or reverse. The label material can thus be transported in roll form, stored, and forwarded for later processing. The adhesive can, for example, be a heat-activated adhesive, a hot-setting adhesive, or a pressure-sensitive adhesive. The web thus produced, consisting of a label film and a carrier, is then die-cut to produce individual labels; the matrix surrounding these labels is removed prior to further processing. After separation from the matrix material, the labels remain on the carrier in a spaced-apart sequence before being detached from the carrier using a peel-off edge and adhered to the bottle to be labeled.According to the invention, crease-free and continuously reliable labeling of continuously delivered bottles is ensured by the label being made of polyethylene and having a thickness of 100 to 150 μm, preferably 100 to 120 μm. The carrier is made of glassine with a density of 62 to 90 g / m. 2or a plastic film as a release carrier with a film thickness between 23 μm and 30 μm, and the adhesive is made of an acrylate. Due to the selected material and material thickness, the label has a rigidity that enables crease-free labeling and continuous operation at a high throughput rate. The method according to the invention operates reliably, but at the same time is sufficiently material-efficient. When using polyethylene as the label material and a plastic material for the bottle to be labeled made of a different material, in particular PP or PET, subsequent separation of the high-purity PE and PET materials in a washing and settling process is possible due to their different densities.

[0009] The acrylate adhesive used in the process according to the invention has the advantage that the surfaces produced by blow molding, which still have a "residual heat" and are thus still subject to slight shrinkage processes, have the advantage that the adhesive only "takes hold" after the plastic container produced by blow molding has cooled down.

[0010] In any case, experiments have shown that the three conditions mentioned above produce an unexpected result. According to a further development of the present invention, a PE-PET or PP material is used for blow molding, to which recycled plastic granules are added, preferably in an amount of 10 to 50% by weight. This measure serves to promote sustainability. While the addition of plastic granules does lead to different surface tensions in the molded glass product, these are surprisingly compensated for by the improved rigidity of the PE label material and the adhesive.

[0011] PMMA is used in particular as an acrylate adhesive.

[0012] In a specific embodiment of the invention, a container was created by blow molding, consisting of a PET material with a container thickness of 110 μm. After molding, this container was filled with a washing lotion and then sealed.

[0013] For labeling, a series of containers, serially produced by blow molding, was passed through a labeling station, where pre-cut labels, which had already been glued to a carrier, were passed in such a way that the next label was removed from the carrier by a peeler and, starting at an edge, unrolled and affixed to the blow-molded bottle. An acrylic PMMA adhesive was used. The carrier to which the labels were attached prior to labeling consisted of glassine with a density of approximately 75 g / m². 2 .

Claims

Claims 1. A method for labelling PE, PET or PP bottles produced by blow moulding, to which a PE label is affixed after filling, wherein the PE label arranged on a carrier is detached from the surface of the carrier by a 180° deflection and affixed to the PE, PET or PP bottle being conveyed past, characterised by the following features: a) the PE label has a thickness of 100 to 150 μm, preferably 100 to 120 μm, b) the carrier consists of glassine with a density of 62 to 90 g / m 2 or a plastic film as a release carrier and c) the adhesive used is an acrylate which is applied to the underside of the label.

2. Process according to claim 1, characterized in that the PP, PET or PE bottle contains proportions of recycled plastic granulate, preferably in an amount of 10 to 50% by weight.

3. Method according to claim 1 or 2, characterized in that the adhesive is a PMMA.