DE102013022606B3 - Foil for labels and cover strips - Google Patents

Abstract

Film with at least a first layer (1) comprising at least 50% by weight random heterophasic polypropylene (block) copolymer and another polypropylene polymer or polypropylene copolymer, a second layer comprising a mineral oil-impermeable barrier layer (3), and a adhesion-promoting layer (4) between layers (1) and (3),
the heterophasic polypropylene random (block) copolymer consisting of a homogeneous phase of polypropylene with small amounts of ethylene and butene in random (block) distribution and a finely dispersed phase of ethylene-propylene rubber, the ethylene-propylene rubber being a random copolymer of ethylene and propylene, in which ethylene predominates, and
the film comprising a layer (1') corresponding in composition to layer (1) and a second adhesion-promoting layer (4') between layers (3) and (1').

Description

The present invention relates to a film for labels and covering webs which is dimensionally stable when heat treated on one side.

For applications in which heat treatment occurs on one side, PVC films are mostly used in the prior art, since these do not have a curling effect. The problem with PVC films, however, is their lack of recyclability.

From the pamphlet DE10246864A1 a PVC-free covering sheet made of a film-bitumen composite comprising two film layers with different thermal expansion coefficients to avoid the bowl or curling effect is known.

US 2011/0067799 A and DE 699 14 383 T2 each explain that heterophasic polymers are usually referred to as polymers in which one polymer, in particular an elastomeric one, is dispersed in a matrix of another polymer. This can be a "real" blend or a reactor blend. Such heterophasic polymers are often referred to as block copolymers, regardless of whether they are present as a “true” blend or as a so-called reactor blend.

U.S. 5,837,369 A discloses a film with a sealing layer and a single- or multi-layer base layer, the sealing layer a) comprising in particular 40 to 80% by weight of a random heterophasic polypropylene (block) copolymer as component a2) and the base layer b) in particular a barrier layer b2) or b4) made of polyamide and/or a metal or metal oxide layer. Especially in connection with the one mentioned there EP 0 373 660 A , the random heterophasic polypropylene (block) copolymer consists in particular of a reactor blend of a random propylene-ethylene-butene (block) copolymer (= matrix) and an ethylene-propylene rubber (= dispersed phase).

EP 2 602 281 A1 discloses a coextruded film with the layer sequence A/B, where A stands for a layer made of a polypropylene (=PP) composition PP-C and B for a barrier layer made of polyamide. The composition PP-C comprises at least 90% by weight of a PP, which is in particular a random heterophasic polypropylene (block) copolymer, and 1 to 10% by weight of another PP (=H-PP).

DE 196 13 959 A1 discloses a lidding film 16 which comprises a sealing layer 22 made from a random heterophasic polypropylene (block) copolymer and a barrier layer made from, in particular, polyamide or metal.

WO 2003/018312 A1 discloses a multilayer film 6 with the layer sequence 1/2/3/2/4/5, with 1 for a polyolefin protective layer, 2 for an adhesion promoter layer, 3 for a barrier layer made in particular of a polyamide copolymer, 4 for a core layer of a random heterophasic polypropylene (block) copolymer and 5 stands for a polyolefin sealing layer.

It is an object of the present invention to provide a recyclable film that is inexpensive and comparable in performance to PVC film. A further object is to provide labels and covering webs comprising the film.

The above object is achieved by a film according to claim 1. Preferred embodiments are presented in the dependent claims.

Random polypropylene heterophasic (block) copolymer or "r-PP-HeCo" for short) consists of a homogeneous phase of polypropylene with small amounts of ethylene and butene in random (block) distribution . This continuous phase provides rigidity and heat resistance. The second phase is a finely dispersed phase of ethylene-propylene rubber, a random copolymer of ethylene and propylene in which ethylene predominates. This phase ensures internal padding and elasticity, which improves shock resistance and tear resistance. Both phases are produced in situ in the reactor via a sequential polymerization process using Ziegler-Natta or metallocene catalysts.

According to the invention, the first layer has a further polypropylene polymer or polypropylene copolymer.

In a reference example, the film comprises a second layer of polypropylene polymer or polypropylene copolymer.

According to the invention, the film comprises a barrier layer that is impermeable to mineral oils as the second layer. The barrier layer can comprise a polyamide (co)polymer, a polyamide alloy, PET, O-PET or a lacquer. The barrier layer preferably comprises a polyamide copolymer.

According to the invention, the film has an adhesion-promoting layer between the first and the second layer. The adhesion-promoting layer preferably comprises an adhesion-promoting polymer. This is particularly preferably a modified polypropylene. For example, a polypropylene modified with maleic anhydride groups can be used.

According to the invention, the film has a symmetrical structure, with the second layer again being followed by an adhesion-promoting layer and then by a layer corresponding in composition to the first layer.

The thickness of the first layer is preferably at least 5 μm, preferably 10 μm, particularly preferably 15 μm, particularly preferably 20 μm.

The total thickness of the film is preferably at least 20 µm, more preferably at least 40 µm, particularly preferably at least 60 µm and most preferably at least 75 µm.

A reference example relates to a label comprising foil, pressure-sensitive adhesive and paper. Preferably, the label comprises the following 4 layers in the order given: a first layer comprising at least 50% by weight random heterophasic polypropylene (block) copolymer, a second layer of polypropylene polymer or polypropylene copolymer, a third layer of pressure-sensitive adhesive layer and a fourth layer of paper.

• 1 zeigt eine Folie mit zwei Schichten (Referenzbeispiel).
• 2 zeigt eine bevorzugte Ausführungsform einer Folie mit fünf Schichten.
• 3 zeigt eine bevorzugte Ausführungsform eines Etiketts (Referenzbeispiel).
• 4 zeigt eine bevorzugte Ausführungsform einer Abdeckbahn (Rferenzbeispiel).

A further reference example relates to a cover web comprising a film and an adhesive. The cover sheet preferably comprises the following 6 layers in the order given: a first layer comprising at least 50% by weight random heterophasic polypropylene (block) copolymer, a second layer comprising an adhesion promoter, a third layer made of polyamide, a fourth layer comprising an adhesion promoter , a fifth layer corresponding to the first layer, and as the sixth layer comprising an adhesive. The adhesive is preferably bitumen or polybitumen. The adhesive is expediently protected with a release film or release paper as a further layer, which can be removed during application.

• 1 shows a film with two layers (reference example).
• 2 Figure 12 shows a preferred embodiment of a five layer film.
• 3 shows a preferred embodiment of a label (reference example).
• 4 shows a preferred embodiment of a cover sheet (reference example).

1 Reference example) shows a film with at least a first layer (1) comprising a mixture of 50% by weight of polypropylene heterophasic random (block) copolymer and polypropylene heterophasic copolymer. The second layer (2) of the film consists of polypropylene.

The mixture of heterophasic polypropylene (block) copolymer and at least 50 wt “) to the temperature-affected side is avoided. In order to achieve stable processability, coating or printing is preferably carried out below the melting point of all polymers.

It has been shown that the sole use of random polypropylene (r-PP; random polypropylene) for a film produced by the blown film or cast film process due to the resulting molecular orientation for applications in which one-sided temperatures occur, excessive shrinkage and causing curling effects.

On the other hand, curling effects and excessive shrinkage effects can be prevented by using heterophasic random polypropylene copolymer alone or as a mixture of at least 50% by weight of heterophasic random polypropylene copolymer and another polypropylene polymer or polypropylene copolymer, as in 1 present in layer 1 should be avoided.

2 shows a further preferred embodiment of the film according to the invention. The film is designed as a composite of five layers. Layer 1 corresponds to the layer in the first embodiment. An adhesion promoting layer 4 follows. This is followed by a barrier layer 3 which prevents the migration of mineral oils. The barrier layer 3 can consist, for example, of a polyamide, a polyamide alloy, PET, O-PET or a lacquer. This is followed by layers 4' and 1', which correspond to layers 4 and 1, so that a symmetrical structure results overall. Alternatively, a composite film made up of layers 1, 4 and 3 is also possible.

In 3 a reference example of a label is shown. The label consists of the in 1 shown film composite, wherein a pressure-sensitive adhesive layer 6 is applied to the polypropylene layer 2 and a paper carrier 5, preferably made of non-shrinking paper, is applied thereto.

4 shows a reference example of a cover sheet. The covering sheet consists of the in 2 shown film composite from the layers 1, 4, 3, 4 'and 1', wherein a layer of bitumen is applied to the layer 1 '. In addition, an anti-slip coating can be applied to the top of the cover sheet. The covering membrane is particularly suitable for sealing roof surfaces. Alternatively, it is also possible to use a covering sheet made from layers 7, 1, 4 and 3. In both alternatives, the sticky mass is expediently protected with a release film or release paper, which is removed during application.

examples

Application example 1 (reference example):

Label label foil for laser printers

On an as in 3 constructed label was printed with a laser printer on the paper side. The surface of the film was briefly heated to 130 to 135 °C (time: <1 s). Despite the different heating and cooling of the side directly exposed to the temperature and the side facing away from the thermal load, a curling effect could be avoided.

Application example 2 (reference example):

When making an as in 4 During the coating with bitumen, the built-up cover sheet is heated up and cooled down differently during the cooling process on the side directly exposed to the temperature and on the side exposed to the temperature load.

The different temperature loads occur in particular due to the usual counter-cooling during or after the coating with bitumen. The foil is cooled from one side while bitumen is coated on the opposite side. This occurs with direct coating at 160 °C to 170 °C and with indirect coating at up to 140 °C. Despite the one-sided temperature load, the curling effect could be avoided.

• In den Beispielen wurden folgende Rohstoffe verwendet:

r-PPHeCo random Polypropylen heterophasiges (Block)Copolymer der Firma Liondell Basel PP HeCo Polypropylen heterophasiges (Block)Copolymer der Firma Prasken (Ethylen-Anteil 7 bis 9 %) Haftvermittelndes Polymer mit Maleinsäureanhydrid-Gruppenmodifiziertes Polypropylen der Firma Mitsui CoPA Copolyamid, gebildet aus ε-Capolactam-Isophorondiamin undIsoterephthtalsäure, mit einem Isophorondiaminanteilvon circa 5 % der Firma Lanxess r-PP random Polypropylen-Copolymer der Firma Liondell Basell(Ethylen-Anteil 2 bis 4ö) The following examples were also evaluated to evaluate the curling effect:

• The following raw materials were used in the examples:

r-PPHeCo random Polypropylene heterophasic (block) copolymer from Liondell Basel PP HeCo Polypropylene heterophasic (block) copolymer from Prasken (ethylene content 7 to 9%) Adhesion-promoting polymer Polypropylene modified with maleic anhydride groups from Mitsui CoPA Copolyamide, formed from ε-capolactam-isophoronediamine and isoterephthalic acid, with an isophoronediamine content of about 5% from Lanxess r-PP random polypropylene copolymer from Liondell Basell (ethylene content 2 to 4ö)

Example 1 (reference example)

A film was produced from a layer consisting of 100% r-PP HeC o with a layer thickness of 80 μm.

Example 2 (reference example)

A film was produced from a layer of 50% r-PP HeCo and 50% PP HeCo with a layer thickness of 80 μm.

Example 3 (reference example)

A two-layer film was produced. The first layer consisted of r-PP HeCo(50%) and PP HeCo(50%) with a layer thickness of 20 µm. The second layer consisted of 100% PP HeCo with a layer thickness of (60 µm).

Example 4 (reference example)

A three layer film was produced. The first layer consisted of r-PP HeCo(50%) and PP HeCo(50%) and had a layer thickness of 44 µm. The second layer consisted of adhesion-promoting polymer (100%) with a layer thickness of 6 µm. The third layer consisted of CoPA (100%) with a layer thickness of 25 μm.

Example 5

A five layer film was produced. The first layer consisted of r-PP HeCo(50%) and PP HeCo(50%) with a layer thickness of 44 µm. The second layer consisted of adhesion-promoting polymer (100%) with a layer thickness of 6 μm. The third layer consisted of CoPA (100%) with a layer thickness of 25 μm. The fourth layer consisted of adhesion-promoting polymer (100%) with a layer thickness of 6 μm. The fifth layer consisted of r-PP HeCo(50%) and PP HeCo(50%) with a layer thickness of 44 µm.

In addition, the following comparative examples were prepared.

Comparative example 1

A film was produced from a layer consisting of 50% r-PP and 50% PP HeCo with a layer thickness of 80 μm.

Comparative example 2

A two-layer film was produced. The first layer consisted of 50% r-PP and PP HeCo(50%) with a

layer thickness of 20 µm. The second layer consisted of PP HeCo (100%) with a layer thickness of (60 μm).

Comparative example 3

A film consisting of a layer consisting of 100% PP HeCo with a layer thickness of 80 μm was produced.

• Die Folien wurden auf einem Papierträger (Schrumpf bei 110 °C für 30 s < 1 %) mit einer selbstklebenden Masse (Klebeband der Firma 3M) fixiert und mittels einem Laserdrucker (Firma HP; Typ 1320n) bedruckt. Der Fixierprozess der Farbpartikel auf der Folie im Laserdrucker hat eine Temperatur von 130 bis135 °C und eine Dauer von 0,5 bis 1 s.

The examples and comparative examples were evaluated as follows:

• The films were fixed to a paper carrier (shrinkage at 110° C. for 30 s <1%) using a self-adhesive composition (adhesive tape from 3M) and printed using a laser printer (HP; type 1320n). The process of fixing the color particles on the foil in the laser printer has a temperature of 130 to 135 °C and a duration of 0.5 to 1 s.

++

kein Curling;

+

geringes Curling;

-

starkes Curling;

- -

sehr starkes Curling

Curling is determined using the following rating scale:

++

no curling;

+

minor curling;

-

strong curling;

- -

very strong curling

The results are shown in Table 1. Table 1 slide samples curling Example 1* ++ Example 2* ++ Example 3* + Comparative example 1 - Comparative example 2 - Comparative example 3 - *Reference examples

reference list

1

first layer comprising at least 50% by weight random heterophasic polypropylene (block) copolymer (e.g. 50%r-PP HeCo and 50% PP-HeCo)

2

second layer comprising polypropylene polymer or polypropylene copolymer (e.g. PP-HeCo)

3

barrier layer impermeable to mineral oils (e.g. PA)

4

adhesion-promoting layer

5

Paper backing (preferably non-shrink)

6

pressure sensitive adhesive

7

sticky mass (bitumen or self-adhesive caulking compound)

Claims (4)

Film with at least a first layer (1) comprising at least 50% by weight random heterophasic polypropylene (block) copolymer and another polypropylene polymer or polypropylene copolymer, a second layer comprising a mineral oil-impermeable barrier layer (3), and a adhesion-promoting layer (4) between layers (1) and (3), the heterophasic polypropylene random (block) copolymer consisting of a homogeneous phase of polypropylene with small amounts of ethylene and butene in random (block) distribution and a finely dispersed phase of ethylene-propylene rubber, the ethylene-propylene rubber being a random copolymer of ethylene and propylene, in which ethylene predominates, and the film comprising a layer (1') corresponding in composition to layer (1) and a second adhesion-promoting layer (4') between layers (3) and (1'). slide after claim 1 , wherein the barrier layer (3) comprises a polyamide copolymer. Slide after one of the Claims 1 or 2 , wherein the thickness of the layer (1) is at least 5 pm. Slide after one of the Claims 1 until 3 , the total thickness of the foil being at least 20 µm.

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