EP2683546A1

EP2683546A1 - A laminate web

Info

Publication number: EP2683546A1
Application number: EP12757200.6A
Authority: EP
Inventors: Noel Mitchell; Markus KIVELÄ
Original assignee: UPM Raflatac Oy
Current assignee: UPM Raflatac Oy
Priority date: 2011-03-11
Filing date: 2012-03-09
Publication date: 2014-01-15
Also published as: CN103547444A; WO2012123633A1; EP2683546A4; CN103547444B

Abstract

The invention relates to a label laminate web comprising an adhesive layer in between the facestock film and the release liner, wherein the adhesive layer comprises a hydrophilic acrylic block copolymer. The invention also relates to a method for manufacturing labels and to a method for attaching a label onto a humid surface of an item. The invention further relates to use of labels for labelling of an item and to a combination of an item and a label.

Description

A laminate web

Field of the Invention

The present invention relates to laminate webs and labels made thereof. More specifically, the invention relates to a composition of an adhesive layer.

Background of the Invention

In the beverage industry, and in particular in the beer industry, glass bottles are most often decorated with paper labels. The adhesive used with paper labels is a so-called wet glue, most commonly based on casein. The cost of such labels and adhesive is relatively low. However, this process suffers from the disadvantage that to change from one label shape or size to another involves considerable machine downtime and therefore costs. In addition this process also involves considerable downtime to set-up as well as to clean the machine after use. One further major disadvantage in this process is that it does not allow clear labels to be used as clear wet-glue labels have not been successful due to the inevitable presence of bubbles in the final adhesive layer which is unacceptable.

These problems have in the main been resolved through the use of clear pressure-sensitive filmic labels. Typically these labels consist of a release liner and a polymeric facestock which are laminated together with a pressure sensitive adhesive layer (PSA) in between. However, the use of clear filmic pressure-sensitive labels has necessitated that the surface of filled bottles to be labelled must be completely dry and free of condensation prior to labelling. This was not the case with the use of wet-glue paper labels. Therefore, in the case of clear filmic pressure-sensitive labels, this additional drying process for the bottles is a major cost factor for the breweries. This is however essential, if clear filmic pressure-sensitive labels are to be used, as the adhesion of such labels is not satisfactory on moist or condensated surfaces i.e. on a wet surface or a surface of condensed water vapour. In this case the labels will very often slip on the condensated surface and will therefore be misaligned, or they dry and adhesive surface will become milky due to interaction with the water on the surface of the bottle or in the worst cases the label will not adhere at all and simply fall off.

Summary of the Invention

It is an object of the present invention to provide a laminate web for labels comprising a clear plastic film facestock and an adhesive, wherein the adhesive is suitable for adhering to humid surfaces, i.e. surfaces having residual moisture.

According to a first aspect of the present invention a label laminate web is provided. The laminated web comprises a polymeric facestock film, a siliconised release liner and an adhesive layer in between the facestock film and the release liner. The adhesive layer includes at least a hydrophilic acrylic block copolymer.

According to a second aspect of the invention a method for attaching a label onto the surface of an item is provided. The method comprises at least removing of the release liner to expose the adhesive layer and attaching the adhesive layer against the humid surface of an item.

According to a third aspect of the invention a labelled item is provided.

According to a fourth aspect of the invention a method for producing labels is provided. The method comprises at least combining an adhesive layer, wherein the adhesive layer comprises a hydrophilic acrylic block copolymer, to one side of a release liner and to one side of a facestock so as to form a laminated web structure, printing and cutting the laminated web structure so as to form labels.

According to a fifth aspect of the invention a use a label laminate web for labelling of an item, such as a bottle or container is provided.

Further embodiments are presented in the dependent claims. The adhesive layer of the label laminate web may include solid resin, wherein the solid resin may be a polyvinyl methyl ether) copolymer, a fully hydrogenated rosin or a mixture thereof. The adhesive layer may also include a poly(ethylene glycol).

In the adhesive layer an amount of hydrophilic acrylic block copolymer may be from 10 to 60 weight-%, preferably from 15 to 50 weight-%, and most preferably from 20 to 40 weight-%.

The humid surface of the item may comprise residual moisture or condensated water vapour.

The item, such as a bottle, wherein the label is attached may contain beverage. The beverage may be beer.

Description of the Drawings The invention will be explained in the following with reference to the appended drawings, where

Fig. 1 presents, in a cross-sectional view, a laminate web for labels, Fig. 2 presents, in a in a cross-sectional view, a laminate web comprising die-cut labels,

Fig. 3 presents, in a cross-sectional view, individual labels released from the liner,

Fig. 4 presents, in a side view, a label attached to a surface of an item,

Fig. 5 a-b presents, in a side view, a moist surface of an item and a label attached to the moist surface. Description of the Invention

The novel and innovative new solution involves the use of a special adhesive which does not require that the bottles are pre-dried prior to labelling which therefore enables a substantial reduction in operating costs for the breweries.

According to one aspect of the invention there is provided a laminate web for labels comprising a polymeric facestock and an adhesive against the facestock, wherein the adhesive is capable of rapidly absorbing moisture on the surface of the bottles without losing its adhesion or cohesion characteristics. This rapid, almost instantaneous absorption of moisture allows the adhesive to grip firmly to even condensated glass surfaces without slipping.

According to another aspect of the invention there is provided a method for attaching a label onto the surface of an item, the label comprising a facestock, a release liner, and an adhesive layer, wherein the adhesive layer comprises a hydrophilic acrylic block copolymer, the method comprising: removing of the release liner to expose the adhesive layer;

attaching the adhesive layer against the surface of an humid item.

Referring to the Fig. 1 , a laminate web structure 1 for labels comprises a siliconised release liner 6 and a facestock layer 2, also referred as a face layer or facing material, which release liner and facestock layer are laminated together with an adhesive layer 4 in between. The laminate web for labels may also comprise other layer or layers, such as additional adhesive layer(s), print layer(s) or protective layer(s), in order to improve the label properties or appearance. Graphical patterns may be printed on the facestock layer. The printed facestock may also be overlaminated, for example in order to protect printing. A label refers to a product which comprises at least a face layer 2 and an adhesive layer 4. Prior to the application the label comprises also a release liner 6. The label may be a pressure-sensitive adhesive (PSA) label. PSA labels are adhered to the surface of an article through an adhesive layer forming a bond when pressure is applied on the label at room temperature. PSA labels may also be called as self-adhesive or self-stick labels.

Referring to the Fig. 2, individual labels 3 of desired shape and size may be die-cut from laminate web 1 . After cutting, a number of individual labels 3 may be attached to a liner 6, which remains uncut and continuous. Alternatively, the individual labels 3 may be completely separate, i.e. also the liner 6 may be cut. Referring to the Fig. 3, after cutting, the labels may be separated from the liner. Thus a surface of an adhesive layer 4 of the label is exposed so that the adhesive layer can be attached to a surface 7 of an item 5, such as a glass or plastic bottle or other container, as presented in Fig. 4. The item may contain beverage, for example beer.

According to one embodiment, the facestock 2 is a monolayer polymer film. Alternatively, a multilayer polymer film may be used as a facestock layer. The polymer film(s) may be oriented or non-oriented. If oriented, the film may be monoaxially oriented or biaxially oriented. Biaxially oriented (BO) films are oriented in both machine (MD) and transverse directions (TD). Monoaxially oriented films may be oriented either in machine direction or transverse direction. Preferably the films are biaxially oriented. Thanks to the biaxial orientation, the films are more stable in subsequent label manufacturing process, i.e. during the printing and converting process. Additionally, biaxially oriented films, such as BOPP, are very economical.

The polymer film may be based on synthetic or biodegradable polymers or polymers derived from renewable resources. The film may include homopolymers, copolymers or it may be a polymer blend. The facestock may consists of polyolefin, such as a polypropylene (PP) or polyethylene (PE), polyethylene terephthalate (PET), cellulosic film, polystyrene (PS), polylactide (PLA), or any combination of thereof. The film may absorb moisture. Alternatively the film may be non-moisture penetrable. The monolayer polymer film of a facestock may have a thickness between 40 and 60 microns. The facestock having multilayer structure may have individual plastic film layers having thickness of 15 to 35 microns. The facestock is preferably clear, i.e. substantially transparent to visible light. The clear facestock layer is preferred, as it allows the objects beneath such layer, i.e. the bottle or its contents, to be seen through such layer. The facestock has a haze less than 25%, preferably less than 15%, and most preferably less than 10% (according to standard ASTM D1003). The facestock may also be glossy, i.e. having a shiny appearance. The facestock may have a gloss greater than 50%, when measured according to standard DIN 67530/2 with an angle of 45°. In order to have optimum clear-on-clear effect, i.e. very clear label, the facestocks which are highly transparent and glossy are preferred. Also white facestock layer may be used. White facestock may have a inorganic pigment, such as Ti0₂, as a filler material in a polymer film.

The liner 6 of the laminate web structure may be paper based, such as kraft or glassine paper. Alternatively it may be a plastic film, such as a polypropylene (PP) or polyester film. If high dispensing speeds are used in label dispensing process, i.e. during the removal of the liner and application of the label to the substrate surface, the plastic film liners are preferred. The use of a plastic liner would also result in a smoother adhesive coating with a further enhancement of the clarity of the label. A thickness of a liner may be from 12 to 50 microns, preferably from 20-30 microns.

According to one embodiment, the adhesive layer is clear. The adhesive layer may have a haze value less than 10%, preferably less than 5%. Clear adhesive layer is preferred for clear labels, i.e. labels which are substantially transparent to visible light. Additionally, the adhesive has excellent initial tack and adhesion. It will also display good cohesive properties and good adhesion to moist glass surfaces, which substantially reduces the operating costs of breweries as the pre-drying step is no longer necessary. Further, the milkiness of the adhesive layer as a consequence of the interaction of the adhesive with water on the surface of the bottle, may be avoided.

Thanks to the adhesive layer, additional drying process of the items, such as bottles, may be avoided. For example, bottles may have moisture on the surface as a consequence of bringing filled bottles into a warmer environment for labelling. Labels may be attached on moist or condensated surfaces, i.e. on a wet surface or a surface having condensed water vapour. Thanks to the adhesive layer, slip and misalignment of the label on the moist surface can be avoided. The tack of the label to the moist surface and absorption of moisture is preferably immediate. Preferably an instant grab to the moist bottle surface is achieved.

Fig. 5a presents a surface 7 of an item having a moist surface, i.e. a surface having water droplets 8. In Fig. 5b is a view of a label 3 attached onto the moist surface by an adhesive layer 4. The adhesive layer 4 is able to absorb the water droplets 8 without losing adhesion or cohesion characteristics of the adhesive, thus providing an immediate adherence of the label to the surface.

According to one embodiment, the adhesive layer comprises a hydrophilic acrylic block copolymer. The acrylic copolymer may be an acrylic polymer with poly(methyl methacrylate) (PMMA) end-blocks with hydrophilic co- monomers in the mid-block. PMMA end-blocks may have a relatively high glass transition temperature which imparts excellent cohesion to the polymer. The hydrophilic mid-block may be relatively soft with a glass transition temperature of approximately from -30° C to - 50° C which imparts good tack properties to the adhesive and high water adsorption. For example, an adhesive layer may comprise an acrylic polymer available from Arkema under the name of Nanostrength CRPH. An adhesive layer may comprise from 10 to 60 weight-% of a hydrophilic acrylic block copolymer, preferably from 15 to 50 weight-%, and most preferably from 20 to 40 weight-%. Additionally the adhesive layer includes other components, such as solid and/or liquid resins or other modifiers. According to one embodiment, the adhesive composition is modified. It has been found that in order to be able to formulate an optimum adhesive this polymer had to be substantially modified with both solid and liquid resins. Such modifications are also essential in order to achieve a suitable melt- viscosity so that the resultant adhesive can be coated on commercial hot- melt coating equipment. According to an embodiment the adhesive layer includes at least one solid resin. Alternatively, a mixture of two or more solid resins may be used. A suitable solid resin may be a polyvinyl methyl ether) copolymer, for example, available from BASF under the name of Lutonal M40. Also thermoplastic acidic resin, such as fully hydrogenated rosin, may be used. For example, Foral AX-E from Eastman Chemical.

Adhesive layer may also include liquid resin. Suitable liquid resins may be low molecular weight poly(ethylene glycols) in the range of molecular weight from 400 to 1000. Such products are available, for example, from Dow and BASF.

An adhesive layer composition may include solid resin(s) from 40 to 90 wt-%, preferably from 40 to 80 wt-%. The amount of liquid resin may be from 0 to 50 wt-%, and preferably less than 35 wt-%.

As an example, a suitable adhesive layer composition comprises at least an acrylic polymer with poly(methyl methacrylate) (PMMA) end-blocks with hydrophilic co-monomers in the mid-block and a solid resin of polyvinyl methyl ether) copolymer and/or a liquid resin of low molecular weight polyethylene glycols. The composition may also include pH modifier. Thanks to the pH modifier, the pH of the adhesive layer may be varied in order to provide optimal water absorption of the adhesive layer. For example, the adhesive layer having higher pH the increased water absorption may be achieved. The pH modifier may be, for example 2 amino 2 methyl propanol. Alternatively triethanolamine may be used.

Example A As an example, the adhesive composition may comprise a formulation as follows: p.b.w. (parts by weight)

Nanostrength CRPH 25

Lutonal M40 40

Pluriol E 600 33 pH modifier 2

total 100

Such an adhesive has been found to be very clear, have excellent initial tack and adhesion and display good cohesive properties and above all good adhesion to moist glass surfaces, which substantially reduces the operating costs of breweries as the pre-drying step is no longer necessary.

Example B

According to another example, the adhesive composition may comprise a formulation:

p.b.w. (parts by weight)

Nanostrength CRPH 32

Lutonal M40 40

Foral AX-E 28

total 100

, wherein Foral AX-E is a solid fully hydrogenated gum rosin.

The formulation exhibits excellent tack and adhesion properties on condensated bottles, i.e. a humid surface of the item, in contrast to the standard acrylic emulsion-based adhesive currently in use. When used for labels the adhesive allows immediate smoothing after the label is applied to the surface of the bottle. The label may be smoothed down by brushes or squeegee rollers. If the grab to these condensated bottles is not good, as in the case of standard acrylic-emulsion based adhesives, then the action of these brushes or squeegee rollers will cause the label to move and be misplaced on the bottle.

For the person skilled in the art, it will be clear that modifications and variations of the products and formulations according to the present invention are perceivable. The various aspects of the invention are also illustrated by the following examples. Example 1 . A laminate web comprising:

a polymeric facestock film;

a siliconised release liner;

an adhesive layer in between the facestock film and the release liner, wherein the adhesive layer comprises a hydrophilic acrylic block copolymer

Example 2. The laminate web according to example 1 , wherein the adhesive layer comprises a polyvinyl methyl ether) copolymer.

Example 3. The laminate web according to example 1 or 2, wherein the adhesive layer comprises a poly(ethylene glycol).

Example 4. The laminate web according to any of the examples 1 to 3, wherein the laminate is printed and die-cut into the labels of a determined shape.

Example 5. The laminate web according to any of the examples 1 -3, wherein the laminate is printed, overlaminated and die-cut into labels of the determined shape.

Example 6. The use of a label according to example 4 or 5 for labelling of an item, such as bottle. Example 7. A method for attaching a label onto the surface of an item, the label comprising a facestock, a release liner, and an adhesive layer, wherein the adhesive layer comprises a hydrophilic acrylic block copolymer, the method comprising:

removing of the release liner to expose the adhesive layer;

attaching the adhesive layer against the surface of a humid item.

Example 8. The method according to example 7, wherein the surface of the item has residual moisture. Example 9. The method according to example 7 or 9, wherein the bottle contains beverage. Example 10. The method according to example 9, wherein the beverage is beer.

Claims

Claims:

1 . A label laminate web comprising:

a polymeric facestock film;

a siliconised release liner;

an adhesive layer in between the facestock film and the release liner, wherein the adhesive layer comprises a hydrophilic acrylic block copolymer.

2. The label laminate web according to claim 1 , wherein the adhesive layer includes solid resin.

3. The label laminate web according to claim 2, wherein the solid resin is a polyvinyl methyl ether) copolymer, a fully hydrogenated rosin or a mixture thereof.

4. The label laminate web according to any of the preceding claims, wherein the adhesive layer includes a poly(ethylene glycol).

5. The label laminate web according to any of the preceding claims, wherein an amount of hydrophilic acrylic block copolymer is from 10 to 60 weight-%, preferably from 15 to 50 weight-%, and most preferably from 20 to 40 weight- %.

6. Use of a label laminate web according to any of the previous claims for labelling of an item, such as a bottle or container.

7. A method for attaching a label onto the surface of an item, the label comprising a facestock, a release liner, and an adhesive layer, wherein the adhesive layer comprises a hydrophilic acrylic block copolymer, the method comprising:

removing of the release liner to expose the adhesive layer;

attaching the adhesive layer against a humid surface of the item.

8. The method according to claim 7, wherein the surface of the item has residual moisture or condensed water vapour.

9. The method according to claim 7 or 8, wherein the item contains beverage.

10. The method according to claim 9, wherein the beverage is beer.

1 1 . A labelled item, wherein the label attached to a surface of the item comprises a polymeric facestock film and an adhesive layer comprising a hydrophilic acrylic block copolymer.

12. The labelled item according to claim 1 1 , wherein the label is attached to the surface having residual moisture or condensated water vapour.

13. A method for producing a label, the method comprising:

combining an adhesive layer, wherein the adhesive layer comprises a hydrophilic acrylic block copolymer, to one side of a release liner and to one side of a facestock so as to form a laminated web structure,

printing and cutting the laminated web structure so as to form labels.