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EP-4735548-A1 - PAPER LABEL

EP4735548A1EP 4735548 A1EP4735548 A1EP 4735548A1EP-4735548-A1

Abstract

The invention relates to a method for manufacturing a paper label (2) comprising a face (1) and a pressure sensitive adhesive layer (4) for adhering the paper label (2) to a surface of an item to be labelled, wherein the face (1) comprises a paper, wherein the method comprises: applying an acrylic adhesive onto a surface, wherein the acrylic adhesive comprises a wash-off additive, the wash-off additive comprising a resinous material and a grafted rosin ester which is a rosin ester grafted with a capped polyalkylene glycol, and drying the acrylic adhesive in order to form an acrylic pressure sensitive adhesive onto the surface, thereby obtaining the paper label The invention relates to a use of a wash-off additive for an acrylic pressure sensitive adhesive of a direct thermal wash-off paper label. The invention further relates to a paper label (2).

Inventors

  • PIRKKANEN, SARI
  • PERNECKER, TIBOR

Assignees

  • UPM Raflatac Oy

Dates

Publication Date
20260506
Application Date
20240617

Claims (19)

  1. 1 . A method for manufacturing a paper label (2) comprising a face (1 ) and a pressure sensitive adhesive layer (4) for adhering the paper label (2) to a surface of an item to be labelled, wherein the face (1 ) comprises a paper, wherein the method comprises: A) applying an acrylic adhesive onto a first surface of the face (1 ), wherein the acrylic adhesive comprises a wash-off additive, the wash-off additive comprising o preferably, an aqueous phase, o a resinous material, preferably selected from a group consisting of a hydrocarbon resin, an alkyd resin, a polyamide resin, a rosin resin, and mixtures thereof, and o a grafted rosin ester which is a rosin ester grafted with a capped polyalkylene glycol, wherein the capped polyalkylene glycol is a polyalkylene glycol end-capped by an alkyl ether, preferably the capped polyalkylene glycol is a methyl ether capped polyethylene glycol, and drying the acrylic adhesive in order to form an acrylic pressure sensitive adhesive onto the first surface of the face (1 ), or B) applying an acrylic adhesive onto a carrier material, wherein the acrylic adhesive comprises a wash-off additive, the wash-off additive comprising o preferably, an aqueous phase, o a resinous material, preferably selected from a group consisting of a hydrocarbon resin, an alkyd resin, a polyamide resin, a rosin resin, and mixtures thereof, and o a grafted rosin ester which is a rosin ester grafted with a capped polyalkylene glycol, wherein the capped polyalkylene glycol is a polyalkylene glycol end-capped by an alkyl ether, preferably the capped polyalkylene glycol is a methyl ether capped polyethylene glycol, drying the acrylic adhesive in order to form an acrylic pressure sensitive adhesive onto the carrier material, and transferring the acrylic pressure sensitive adhesive to the first surface of the face (1 ), thereby obtaining the paper label.
  2. 2. The method according to claim 1 , wherein a polymer gel content of the acrylic adhesive is at least 60% and 75% at the most.
  3. 3. The method according to claim 1 or 2, wherein a mean particle size of the acrylic adhesive is at least 100 nm and 800 nm at the most, measured as a mean particle diameter.
  4. 4. A paper label (2) comprising a face (1 ) and a pressure sensitive adhesive layer (4) for adhering the label (2) to a surface of an item to be labelled, wherein the face (1 ) comprises a paper, and the pressure sensitive adhesive layer (4) comprises an acrylic pressure sensitive adhesive comprising a wash-off additive, the wash-off additive comprising o a resinous material, preferably selected from a group consisting of a hydrocarbon resin, an alkyd resin, a polyamide resin, a rosin resin, and mixtures thereof, and o a grafted rosin ester which is a rosin ester grafted with a capped polyalkylene glycol, wherein the capped polyalkylene glycol is a polyalkylene glycol end-capped by an alkyl ether, preferably the capped polyalkylene glycol is a methyl ether capped polyethylene glycol.
  5. 5. The method or the paper label (2) according to any of the preceding claims, wherein an amount of the wash-off additive is equal to or more than 0.5 wt.%, preferably equal to or more than 1 wt.%, calculated from total dry weight of the acrylic adhesive.
  6. 6. The method or the paper label (2) according to any of the preceding claims, wherein an/the amount of the wash-off additive is equal to or less than 3 wt.%, calculated from total dry weight of the acrylic adhesive.
  7. 7. The method or the paper label (2) according to any of the preceding claims, wherein an amount of the grafted rosin ester with respect to the resinous material is from 1 wt.% to 8 wt.%.
  8. 8. The method or the paper label (2) according to any of the preceding claims, wherein the polyalkylene glycol is a polyethylene glycol.
  9. 9. The method or the paper label (2) according to any of the preceding claims, wherein the acrylic adhesive comprises 2-ethylhexyl acrylate (2-EHA).
  10. 10. The method or the paper label (2) according to any of the preceding claims, wherein the resinous material comprises or consists of the rosin resin.
  11. 11. The method or the paper label (2) according to any of the preceding claims, wherein a molar ratio between the rosin ester and the capped polyalkylene glycol is 0.05:1 to 1 :1 , preferably at least 0.4:1 , and most preferably from 0.7:1 to 0.9:1 .
  12. 12. The method or the paper label (2) according to any of the preceding claims, wherein the alkyl ether is a methyl ether.
  13. 13. The method or the paper label (2) according to any of the preceding claims, wherein the paper label is a direct thermal paper label.
  14. 14. The method or the paper label (2) according to any of the preceding claims, wherein the paper label is a linerless paper label.
  15. 15. The method or the paper label (2) according to any of the preceding claims 1 to 13, wherein the paper label is a paper label laminate comprising a release liner.
  16. 16. The method or the paper label (2) according to any of the preceding claims, wherein the paper label (2) is a wash-off paper label.
  17. 17. An article, preferably a beverage bottle, such as a polyolefin bottle, comprising the paper label (2) according to any of the claims 4-16 adhered to a surface of the article.
  18. 18. A use of a wash-off additive comprising a resinous material and a grafted rosin ester which is a rosin ester grafted with a capped polyalkylene glycol, wherein the capped polyalkylene glycol is a polyalkylene glycol end-capped by an alkyl ether, for an acrylic pressure sensitive adhesive of a direct thermal wash-off paper label.
  19. 19. A use of the paper label (2) according to any of the claims 4-16 for labelling of a beverage bottle.

Description

PAPER LABEL Technical field The application relates to paper labels. The application particularly relates to pressure-sensitive wash-off paper labels. The application further relates to a method for manufacturing a paper label. The application relates to use of a wash-off additive for paper labels. Background It is general practice to apply a label to a surface of an item to provide decoration, and/or to display information about the product being sold, such as the content of the item, a trade name or logo. Alternative type of labelling technologies and labels are available, such as pressure-sensitive, wet glue, wrap around and shrink sleeve labels. Containers, such as bottles in the beverage industry, are generally re-used or recycled. Therefore, there is a need for labels which are easily removed from the surface of the container during washing processes. Thus, removable labels are an important topic, for example, in beverage industry. Summary It is an object of this application to provide a paper label. Another object is to provide a combination of a label and an item, wherein the item is afterwards recycled or reused. Yet another object is to provide a method for manufacturing a paper label. Still another object is to provide a use of a wash-off additive for paper labels for improving washability of paper labels. Aspects of the invention are characterized by what is stated in the independent claims. Some preferred embodiments of the invention are disclosed in the dependent claims. These and other embodiments of the invention are disclosed in the description and figures. Nowadays, producers and end users are looking for environmentally friendly solutions. The paper label according to this specification can be used in various applications for avoiding plastic based labels. Advantageously, the paper label according to this specification is a plastic film free as well as a metal foil free. Thus, preferably, the paper label does not contain, for example, a layer made of a plastic. Technical effect is to provide environmentally friendly product. Conventionally, washing temperatures of wash-off processes have been around +85°C. Due to environmental and cost reasons, nowadays a new target is to decrease washing temperature to +40°C. However, washing temperatures below 50°C have been challenging for PSA labels. Surprisingly, the novel paper label can be washed efficiently during recycling process of plastic bottles. The novel paper label can be efficiently washed in plain water by using temperatures down to 40°C. Thus, the paper labels do not need alkaline conditions for the washing process. Further, thanks to the novel solution, wash-off time of paper labels can be substantially decreased. Particularly, the wash-off time of the paper labels can be substantially decreased at 40°C in plain water, compared to solutions without the wash-off additive. Thanks to the novel paper label, desired properties for labels can be obtained in more environmentally friendly way than with plastic based wash-off labels. Further, as discussed, the paper label can be recycled at 40°C by using plain water. The reduced temperature and wash-off time, as well as a washing process without an alkaline agent, is advantageous for the environment. The paper label according to this specification is typically a wash-off paper label. In an advantageous embodiment, the paper label is a direct thermal wash-off paper label, most preferably a direct thermal linerless wash-off paper label. A paper label according to this specification comprises a face and a pressure sensitive adhesive layer for adhering the paper label to a surface of an item to be labelled. The face according to this specification comprises a paper. The pressure sensitive adhesive layer of the paper label can comprise an acrylic pressure sensitive adhesive which comprises a wash-off additive. The wash-off additive can comprise a resinous material, preferably selected from a group consisting of a hydrocarbon resin, an alkyd resin, a polyamide resin, a rosin resin, and mixtures thereof, and a grafted rosin ester which is a rosin ester grafted with a capped polyalkylene glycol. The capped polyalkylene glycol is a polyalkylene glycol end-capped by an alkyl ether, preferably the capped polyalkylene glycol is a methyl ether capped polyethylene glycol. Technical effect of the wash-off additive is that washability of the paper label comprising an acrylic adhesive is substantially improved. Surprisingly, the novel paper label comprising the modified adhesive comprising the acrylic adhesive and the wash-off additive clearly improved acrylic polymer wash-off properties in low temperature washing processes at +40°C in water, without an alkaline agent. For improving efficiency of the wash-off additive, an amount of the wash-off additive can be more than 0.5 wt.%. The wash-off additive can start to improve washability of the paper label even when a very small amount of more than 0.5 wt.% is