Washaway label

Abstract

The present invention relates to a method of manufacturing a label (2) comprising a face (1) and a pressure-sensitive adhesive layer (4) wherein the method comprises the steps of applying an acrylic adhesive to a first surface of the face (1) wherein the acrylic adhesive comprises a wash-off additive comprising a resinous material and a grafted rosin ester, and drying the acrylic adhesive in order to shape the acrylic pressure-sensitive adhesive onto the first surface of the face (1), thereby obtaining the label (2). The invention further relates to a label comprising a face (1) and a pressure-sensitive adhesive layer (4) wherein the acrylic adhesive comprises a rinse-off additive comprising a resinous material and a grafted rosin ester.

Description

TECHNICAL FIELD

[0001] The present application relates to pressure-sensitive wash-off labels. The present application further relates to a method of manufacturing pressure-sensitive wash-off labels. BACKGROUND ART

[0002] It is common practice to label the surface of an object in order to provide decoration and / or display information about the product being sold, such as the contents of the object, the trade name, or the logo. Alternative types of labeling techniques and labels are available, such as pressure-sensitive, wet glue, wrap around, and shrink sleeve labels.

[0003] Labels include, for example, labels for beverages, food, health and personal care products, pharmaceuticals, industrial chemicals, household chemicals, or retail product packaging.

[0004] Some exemplary categories of labels include: repositionable labels, removable labels, (washable) wash-off labels, resealable labels, no-look labels, deepfreezer labels, and security labels.

[0005] Containers (such as bottles) in the beverage industry are typically reused or recycled. Therefore, there is a need for labels that are easily removable from the surface of the container during washing. Thus, wash-off labels are an important topic, for example, in the beverage industry.

[0006] The present application specifically relates to pressure-sensitive wash-off labels that can be washed off from an article. SUMMARY OF THE INVENTION

[0007] The object of the present application is to provide labels. Another object is to provide a combination of a label and an item, where the item is recycled or reused afterwards. Yet another object is to provide a method of manufacturing labels.

[0008] Preferably, the label according to the present application is a pressure-sensitive wash-off label.

[0009] Aspects of the present invention are characterized by what is stated in the independent claims. Some preferred embodiments are disclosed in the dependent claims. These and other embodiments are disclosed in the description and the drawings.

[0010] Conventionally, the washing temperature of the wash-off process is around +85°C. Due to environmental and cost reasons, the new goal now is to reduce the washing temperature to 65°C - 75°C (for film labels) and 40°C (for paper labels).

[0011] The label according to the present application includes a face and a pressure-sensitive adhesive layer for adhering the label to the surface of an object to be labeled.

[0012] The face according to the present application may include a thermoplastic film, preferably an oriented thermoplastic film. Alternatively, the face may be a paper face containing cellulose fibers.

[0013] The pressure-sensitive adhesive layer of the label may include an acrylic pressure-sensitive adhesive including a wash-off additive.

[0014] Preferably, the coating layer of the acrylic pressure-sensitive adhesive includes:

[0015] - butyl acrylate, or

[0016] - 2-ethylhexyl acrylate, or

[0017] - butyl acrylate and 2-ethylhexyl acrylate.

[0018] The total content of the butyl acrylate and 2-hydroxyethyl acrylate may be at least 50% by weight, more preferably at least 70% by weight, more preferably at least 80% by weight, and most preferably at least 85% by weight, calculated based on the dry weight of the acrylic adhesive. These acrylic adhesives may be particularly advantageous for the label.

[0019] The coating layer of the acrylic pressure-sensitive adhesive may include:

[0020] - abietic acid, and / or

[0021] - a copolymer of vinyl acetate and ethylene (VAE).

[0022] The wash-off additive may include a resinous material and a grafted rosin ester. The resinous material is preferably selected from hydrocarbon resins, alkyd resins, polyamide resins, rosin resins, and mixtures thereof. The grafted rosin ester is a rosin ester grafted with a blocked polyalkylene glycol. The blocked polyalkylene glycol is a polyalkylene glycol terminated with an alkyl ether end. Preferably, the blocked polyalkylene glycol is a methyl ether-terminated polyethylene glycol. The technical effect of the wash-off additive is that it significantly improves the washability of the label containing the acrylic adhesive. Unexpectedly, the novel label containing the modified adhesive clearly improves the acrylic polymer properties in a low-temperature washing process. The modified adhesive includes the acrylic adhesive and the wash-off additive.

[0023] For example, for a film face, the novel label containing the modified adhesive (which contains the acrylic adhesive and the wash-off additive) clearly improves the acrylic polymer properties in a low-temperature washing process at 65 - 75 °C, even when using 1% low-alkali water. Additionally, for a paper face, in the absence of an alkaline reagent, the wash-off additive clearly improves the wash-off property of the acrylic polymer in a low-temperature washing process (40 °C, in water).

[0024] When used in an amount greater than 4 wt% (determined by the total dry weight of the adhesive), the wash-off additive can improve the washability of the label. Preferably, the amount of the wash-off additive is equal to or greater than 5 wt%, more preferably equal to or greater than 10 wt%, and most preferably equal to or greater than 15 wt%, determined by the total dry weight of the adhesive. The technical effect is: significantly improving the washability of the label. When the amount of the wash-off additive is at least 10 wt% or at least 15 wt%, the best washing results can be obtained.

[0025] For cost reasons, the amount of the wash-off additive is preferably equal to or less than 25 wt%, more preferably equal to or less than 22 wt%, and most preferably equal to or less than 20 wt%, or equal to or less than 18 wt%, calculated based on the total dry weight of the adhesive.

[0026] In advantageous examples, the amount of the wash-off additive is in the range between 10 wt% and 20 wt%, preferably between 15 wt% and 18 wt%, determined by the total dry weight of the adhesive. The technical effect of these embodiments is: improving the washability of the label in a cost-effective manner.

[0027] The novel label can be easily removed during washing. Therefore, compared with the scenario without using the wash-off additive, the washing time of the label can be significantly shortened.

[0028] To improve the washability of the label, the molar ratio between the rosin ester and the end-capped polyalkylene glycol can be 0.05:1 to 1:1, preferably at least 0.4:1, and most preferably 0.7:1 to 0.9:1.

[0029] To further improve the washability of the label, the amount of the grafted rosin ester relative to the resinous material can be from about 1 wt% to about 8 wt%. In advantageous embodiments, the resinous material contains the rosin resin, or the resinous material is the rosin resin.

[0030] In addition, to further improve the washability of the label, the preferred polyalkylene glycol is polyethylene glycol and the alkyl ether is preferably a methyl ether. Most preferably, the end-capped polyalkylene glycol is a methyl ether-capped polyethylene glycol for an efficient and rapid washing process of the label.

[0031] Preferably, the acrylic adhesive comprises 2-ethylhexyl acrylate and / or butyl acrylate. In the most advantageous embodiment, the acrylic adhesive comprises 2-ethylhexyl acrylate. The acrylic adhesive containing the wash-off additive can cause the pressure-sensitive adhesive to effectively reduce its adhesion to the labeled article during the washing process, such that the PSA can still adhere to the face.

[0032] If the face is a film face, the face may comprise an oriented thermoplastic film, such as a uniaxially oriented film or a biaxially oriented film, preferably a biaxially oriented film. Compared with an unoriented thermoplastic film, the oriented thermoplastic film can provide improved mechanical properties in the orientation direction.

[0033] Thus, the label may comprise a uniaxially oriented thermoplastic film, such as a uniaxially oriented polypropylene film. The uniaxially oriented thermoplastic film may be uniaxially oriented in the machine direction of the film. Alternatively, the uniaxially oriented thermoplastic film may be uniaxially oriented in the transverse direction of the film. Due to the uniaxially oriented film, the mechanical properties of the thermoplastic film can be improved in at least one of the directions, which can facilitate the processability and handling of the film in the process.

[0034] The label may comprise a biaxially oriented thermoplastic film, such as a biaxially oriented polypropylene film. The biaxially oriented thermoplastic film can provide improved mechanical properties in both directions of the film. This can improve the simplicity of handling the film during the processing and washing processes.

[0035] The face may be configured to shrink, preferably asymmetrically. This can allow for a reduction in the washing time of the label.

[0036] As described, the face may comprise a polypropylene film. Polypropylene, for example, is well compatible with polyethylene, and using such similar polymers can provide good adhesion of the label to the article. The rigidity of polypropylene can be less than that of polyester, for example, which can result in less flagging or winging on a curved bottle. Some articles, such as soft bottles, may require such flexibility.

[0037] The face may comprise a glycol-modified polyethylene terephthalate film. The glycol-modified polyethylene terephthalate (PETG) can be effective in providing flexibility to the face.

[0038] As described, the face may be a paper face. The technical effects of the paper face include good mechanical properties, which can facilitate the processing and operation of the label during the label processing process, while the washing additive improves the washability in the washing process.

[0039] A method of manufacturing a label may comprise the steps of, the label comprising a face and a pressure-sensitive adhesive layer for adhering the label to the surface of an article to be labeled:

[0040] - Applying an acrylic adhesive to a first surface of the face, wherein the acrylic adhesive comprises a wash-off additive, the wash-off additive comprising:

[0041] ○ Preferably an aqueous phase,

[0042] ○ A resinous material, preferably selected from: hydrocarbon resins, alkyd resins, polyamide resins, rosin resins, and mixtures thereof, and

[0043] ○ A grafted rosin ester, preferably a rosin ester grafted with a capped polyalkylene glycol, wherein the capped polyalkylene glycol is a polyalkylene glycol terminated with an alkyl ether end,

[0044] Preferably, the capped polyalkylene glycol is a methyl ether-capped polyethylene glycol,

[0045] And

[0046] - Drying the acrylic adhesive to form an acrylic pressure-sensitive adhesive onto the first surface of the face,

[0047] Thereby obtaining the label.

[0048] The polymer gel content of the water-based acrylic adhesive may be at least 10%, preferably at least 20%, more preferably at least 40%, still more preferably at least 50%, and most preferably in the range between 60% and 75%. The technical effect of the polymer gel content (and particularly in the range of at least 50%, preferably 60% to 75%) can improve the adhesive properties of the acrylic adhesive.

[0049] The average particle size of the water-based acrylic adhesive may be at least 100 nm and at most 800 nm, measured as the average particle diameter. Due to this range, the properties of the acrylic adhesive (such as the solid content and viscosity level of the acrylic adhesive) can be controlled and easily adjusted to the desired level.

[0050] The label according to the present application can be adhered to the surface of an article (such as a beverage bottle). Therefore, the label according to the present application can be used for labeling beverage bottles.

[0051] During the washing process, the pressure-sensitive adhesive that is sensitive to the washing conditions is effectively detached from the tagged article. Due to this novel solution, the adhesiveness of the adhesive is effectively reduced during the washing process, thereby providing the technical effect of effectively detaching the label from the article. A further technical effect is to effectively prevent the detached labels from sticking to each other due to the adhesive and forming aggregates.

[0052] Due to this novel solution, the pressure-sensitive adhesive can be easily and quickly deactivatable under washing conditions, such as at a temperature of 65 - 75 °C and under alkaline conditions (for the film face), and in water at 40 °C (for the paper face).

[0053] Alkaline conditions refer to an aqueous solution containing an alkaline reagent, such as NaOH, KOH, LiOH, MgOH, CaOH, or a combination thereof. The most common alkaline reagent is probably sodium hydroxide NaOH, also known as caustic soda. The alkaline liquid usually contains about 2 - 4% (w / w), for example about 2%, of the alkaline reagent. However, due to the novel solution using an acrylic adhesive containing the additive, alkaline conditions (as low as 1%, for example as low as 1% NaOH) can be used together with a washing temperature of 65 - 75 °C to obtain suitable washing conditions for effectively washing off the film label, and for a washing temperature of 40 °C to obtain suitable washing conditions for effectively washing off the paper label, alkaline conditions are not required.

[0054] Therefore, due to the novel label according to the present application, the washing conditions can be more environmentally friendly than traditionally. In addition, the label can be recycled in a cost-effective manner.

[0055] The adhesive according to the present application can be designed to obtain approval for direct or indirect food contact (food safety), which is a requirement in certain food-related label end-use fields. For example, many HDPE bottles require labels with food contact approval.

[0056] Therefore, the adhesive can be suitable for and approved for direct food contact. In addition, the label according to the present application can also be suitable for food applications.

[0057] In one embodiment, since the label contains an acrylic adhesive including the additive for washing off, the life of the washing solution can be extended, and contamination of recycled articles (such as bottles) can be prevented. Brief Description of the Drawings

[0058] Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings, in which:

[0059] Figure 1 An exemplary embodiment of the label is shown in a perspective view,

[0060] Figure 2 shows a cross-section of a label laminate including a die cut label,

[0061] Figure 3 shows a labeled article including a label, and

[0062] Figure 4a -d shows some photos from experimental tests.

[0063] These figures are intended to illustrate the general concept of the disclosed solution. Therefore, the illustrations in the figures do not necessarily scale or imply the exact arrangement of system components. Detailed Description of the Invention

[0064] The present solution is described in more detail below in connection with some embodiments, which should not be considered restrictive.

[0065] The following identifications and markings are used in this application:

[0066] Sx, Sy, Sz orthogonal directions,

[0067] MRK1 marking, such as printing,

[0068] DIR1 first direction,

[0069] DIR2 second direction,

[0070] 1 face,

[0071] 2 label,

[0072] 4 adhesive layer,

[0073] 5 release liner,

[0074] 6 release layer of the release liner,

[0075] 7 substrate,

[0076] 8 label laminate,

[0077] 100 article,

[0078] 101 labeled article

[0079] Unless otherwise explicitly stated, the embodiments and examples described in the claims and the specification can be freely combined with each other.

[0080] In the present application, the terms "comprise" and "comprising" can be used as open-ended terms, but they also include the closed term "consisting of." Therefore, unless otherwise specified, the term "comprising" can be read as "comprising the following or consisting of the following."

[0081] For the purposes of this specification and claims, unless otherwise indicated, all ranges include any combination of the maximum and minimum values ​​disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

[0082] Unless otherwise stated, percentage values ​​relating to amounts of material are dry weight percentages (wt. %).

[0083] The term "web" refers to a continuous sheet of material. The web is typically processed by moving on rollers. Between processing stages, the web may be stored and / or transported as a roll.

[0084] The term "machine direction" (MD) refers to the manufacturing direction of a web, i.e., the running direction of the face or continuous label stack during label manufacturing. In the case of a rolled web, the machine direction refers to the circumferential direction of the roll. In addition, the longitudinal direction of the web is referred to as the machine direction. MD can be equivalent to the direction DIR1 of the label attached to the surface of an object.

[0085] The terms "cross direction" (CD) and "transverse direction" TD refer to the direction transverse to the machine direction. Thus, "cross direction" TD and "transverse direction" CD refer to the direction perpendicular to the running direction of the face or label stack. CD may be equal to the direction DIR2 of the label attached to the surface of the article.

[0086] The term "gsm" means g / m 2 .

[0087] The term "HDPE" refers to high density polyethylene. HDPE preferably has a density of 0.93 to 0.97 g / cm 3 density.

[0088] The term "PP" refers to polypropylene. PP preferably has a carbon content of 0.90 to 0.93 g / cm 3 density.

[0089] The term "polyolefin bottle" refers to a polyolefin bottle, ie a bottle made of polyolefin.

[0090] The term "PET" refers to polyethylene terephthalate, and "PET bottle" refers to a polyethylene terephthalate bottle.

[0091] In this specification, the term "label" refers to a material piece used to label an object. Labels can be used to identify certain content. Labels can be attached to products. The product can be a package, such as a bottle. In other words, labels are suitable for being applied to the surface of an object to provide decoration and / or display information about the product for sale, such as content information, trademark name, logo, barcode, or any other graphics.

[0092] Preferably, the label according to the present application is a wash-off label, also known as a washable label. The term "wash-off label" means that the label can be removed (detached) from the surface of the attached object during subsequent washing processes.

[0093] For film labels, under washing conditions at a temperature of 65 - 75 °C, the adhesive bond between the label and the object to which the label is attached weakens. The chemical effect of the washing solution can further enhance the weakening of adhesion.

[0094] For paper labels, the adhesive bond between the label and the object to which the label is attached weakens under washing conditions at a water temperature of 40 °C.

[0095] Therefore, the label may include an adhesive layer sensitive to washing conditions. The label can be used to label beverage bottles. The label according to the present application is applicable to polyethylene terephthalate (PET) bottles. The label according to the present application is applicable to polyolefin bottles, such as HDPE and PP bottles.

[0096] The term "face" refers to the substrate of the label, also known as the face stock or face material.

[0097] In the present application, the term "adhesive coating" refers to a coating containing an acrylic adhesive.

[0098] The term "PSA" refers to a pressure-sensitive adhesive. The PSA according to the present application is an acrylic pressure-sensitive adhesive.

[0099] The term "PEG" refers to polyethylene glycol.

[0100] The ratio of the total film thickness before and after stretching (orientation) is called the "stretch ratio" or "stretching ratio". It may also be referred to as the orientation ratio. The stretch ratio is the non-oriented (undrawn) film thickness relative to the oriented (drawn) film thickness. The non-oriented film thickness is the thickness after film extrusion and subsequent chilling. When stretching the film, the film thickness can be reduced at the same ratio as the film is stretched or elongated. For example, a film with a thickness of 100 microns before uniaxial orientation is stretched at a stretch ratio of 5. After uniaxial orientation, the film may have a thickness reduced by 5 times, 20 microns. Thus, the stretch ratio (orientation ratio) is 5.

[0101] The term "shrinkable" refers to the property of a plastic film to shrink when exposed to external energy. A shrinkable film can shrink when exposed to high temperature. Heat can be applied via a washing solution. In response to the applied heat, the heat-shrinkable film shrinks.

[0102] The shrinkage can be measured according to the following method: Provide a sample with a measured and marked area of 100mm * 100mm, place the sample in a caustic washing liquid at a temperature of 55°C to 95°C (at 5°C intervals) for 5 minutes, cool the sample in a water bath at a temperature around room temperature, dry the sample, and measure the dimensions of the marked area of the sample. Preferably, use at least 3 or more parallel samples. The shrinkage is determined as the relative change in dimensions.

[0103] Peel adhesion corresponds to the force required to detach a self-adhesive label. In a peel adhesion test, the label is applied to a standard test plate under specific conditions and removed from the plate at a specific angle and speed, according to FINAT Test Method 1: 180 degrees, at 300mm / min (FINAT Technical Handbook 8th edition, 2009 (FINAT Technical Handbook 8 edition, 2009)). th edition,2009))。

[0104] The polymer gel content can be measured using a Dionex ASE 150 solvent extractor according to the following method:

[0105] The Dionex ASE 150 solvent extractor has the following settings: Temperature - 100°C, Static time - 30 minutes, Rinse Volume - 10%, Purge time - 60 seconds, Cell volume - 66mL.

[0106] Apparatus: 66 mL cell, 80 mm x 25 mm cellulose thimble, and acetone.

[0107] The method has the following steps:

[0108] 1) Weigh the dry thimble,

[0109] 2) Add ~1 - 1.5 g of wet adhesive to the thimble by coating a film inside the thimble,

[0110] 3) Dry in an oven until no moisture remains,

[0111] 4) Weigh the thimble + dry adhesive and insert it into the 66 mL cell,

[0112] 5) Run the extractor process,

[0113] 6) Remove the thimble and dry it in an oven until all the acetone has left,

[0114] 7) Repeat steps 5 and 6 two more times for a total of 3 cycles,

[0115] 8) Dry the thimble one last time and measure the weight,

[0116] 9) Calculate the polymer gel content percentage as follows from the values in steps 1, 4, and 8:

[0117] Polymer gel content = 100 * (T AB – T) / (T AA – T)

[0118] where

[0119] Dry weight of thimble = T

[0120] Dry weight before extraction of thimble + adhesive = T AB

[0121] Dry weight after extraction of thimble + adhesive = T AA

[0122] Weight of adhesive before extraction = T AB – T

[0123] Weight of adhesive after extraction = T AA – T.

[0124] Label

[0125] As described, label 2 is preferably a wash-off label. The wash-off label may also be referred to as a washable label, which means that the label can be removed (detached) from the surface of the attached object during a subsequent washing process.

[0126] Therefore, label 2 may include a pressure-sensitive adhesive layer 4 that is sensitive to washing conditions.

[0127] The label (if it is a film label) can be washed at a washing temperature of 65°C or 75°C, where the washing liquid is about 1% to about 4%, preferably about 1% to about 2%, and most preferably about 1% alkaline water. The washing liquid may contain caustic soda, such as sodium hydroxide.

[0128] The label (if it is a paper label) can be washed at a washing temperature of 40°C, where the washing liquid is water. Preferably, the washing liquid for the paper label does not contain alkaline reagents.

[0129] Reference Figures 1-2 , the label may include a face 1 and an adhesive layer 4 on the face 1 for adhering the label to the surface of the object to be labeled.

[0130] Label 2 may include the following layers, or consist of the following layers:

[0131] - Face 1,

[0132] - Acrylic PSA layer 4, and

[0133] - Optionally, a printing layer MRK1.

[0134] A single label 2 can be die-cut from a continuous label web.

[0135] Reference Figure 2 , label 2 can be a label laminate including a release liner 5. The release liner can protect the adhesive layer before the label is adhered to the surface of the object.

[0136] Alternatively, and referring to Figure 1 , the label can be a linerless label without a release liner 5. Eliminating the release liner can reduce the material cost of the label and avoid the disposal of the release liner after labeling. In addition, not including the release liner reduces the thickness of the label roll, and more labels can be provided per roll. Therefore, the label can be a linerless label, such as a printed linerless label.

[0137] At least, if the label is a linerless label without a release liner 5, preferably, there is a release layer at the top of the face to prevent adjacent layers of the linerless label roll from adhering to each other. Preferably, the release layer is a layer that does not cause problems during the washing process, such as a silicone-based layer.

[0138] The label may include the following layers, preferably including the following layers in the following order:

[0139] - Optionally a release layer containing a release agent such as silicone,

[0140] - a face, which comprises an oriented thermoplastic film or paper, and

[0141] - an adhesive layer, which comprises a wash-off additive and an acrylic pressure-sensitive adhesive that is capable of forming a bond upon the application of pressure at room temperature.

[0142] The label may be a printed label. The printed MRK1 may subsequently be top-coated or laminated in order to protect the printing. Instead of or in addition to the top-coating and / or lamination, the opposite side of the face adjacent to the adhesive layer 4 may be printed. The print layer is understood to also include a decoration, which is made of, for example, a metal layer or a metalloid layer (if such a decoration is used in the label).

[0143] Thus, the label 2 comprises at least a face 1, at least one adhesive layer 4, and optionally a release liner 5. The adhesive layer 4 comprises PSA. The PSA is used to enable the label to adhere to an object, an article, or a container.

[0144] The label may further comprise one or more additional layers, such as a primer layer. The primer layer may be provided between the face and the adhesive layer. The primer layer may be provided to increase the adhesion of the adhesive layer to the face.

[0145] In one embodiment, the density of the label is adjusted to a total average density of less than 1.0 g / cm 3 . This causes the label to float in an aqueous solution. For example, in the case of a PET bottle (where the recycling method involves shredding or chopping the plastic bottle), the bottle may sink while the label may float, thus allowing for the efficient collection and recycling of the PET flakes. Therefore, since the flakes of the shredded plastic bottle sink, this allows the label to be easily separated from the bottle, especially when using the total average density and the adhesive, allowing the PSA to be efficiently separated from the bottle.

[0146] Face

[0147] During labeling, the face 1 adheres to the surface of the object through the adhesive layer 4. The face 1 comprises a first surface and a second surface. The first surface may refer to the adhesive side, while the second surface may refer to the top side.

[0148] The face may be a film face, or the face may be a paper face.

[0149] The face may be adapted to be printed by any known printing method, preferably by a gravure or flexographic process. Alternatively, the face may be, for example, direct thermal printable. Thus, the top side (i.e., the second surface of the paper label) may be printable, for example, by using heat.

[0150] Membrane face

[0151] The face may comprise a layer including a thermoplastic film. Thus, the face may comprise a face film. The face film may be a single layer. Alternatively, the face film may have a multi-layer structure including two or more layers.

[0152] Compared to paper-based labels, labels comprising a thermoplastic face have, for example, better wet strength and transparency. In addition, due to the thermoplastic film, the life of the washing solution may be significantly extended.

[0153] The thermoplastic film may be provided by extrusion. A multi-layer structure may be provided by co-extrusion, thus providing a uniform film structure where adjacent film layers are in direct contact with each other.

[0154] Thus, the face may comprise two or more layers of thermoplastic film. Preferably, for environmental reasons and to improve cost efficiency, the face has only one thermoplastic film or only two thermoplastic films.

[0155] Preferably, the thermoplastic film of the face is oriented. The oriented film may be provided, for example, by uniaxial or biaxial stretching. Due to the oriented film, the handling of the face may be easier than without orientation. In addition, the mechanical properties of the label may be improved, which may also affect the washing of the label. Further still, due to orientation, the film may exhibit controllable shrinkage at high temperatures. The high temperature may be applied in the form of a heated washing liquid (which has a temperature of, for example, 65 °C).

[0156] To provide a cost-efficient process in which the film structure can be easily controlled, if the face has a multi-layer structure, all thermoplastic layers of the face preferably have the same orientation.

[0157] As described, the face may comprise a uniaxially or biaxially oriented thermoplastic film. The uniaxially oriented film is preferably oriented in the machine direction. Machine direction orientation is effective for achieving sufficient mechanical properties required for the label dispensing line, where the label separates from the support liner and is applied to the surface of an object.

[0158] Preferably, the face comprises a biaxially oriented thermoplastic film. The biaxial orientation and shrinkage of the film in two directions can affect the removal profile of the label. When the film is brought to a high temperature during washing, the film can shrink back to an unstretched state in both directions. This can improve the efficiency of the label washing process and allow for a reduction in the labeling time. Thus, compared to a uniaxially oriented film, the biaxial orientation and shrinkage of the film can allow for a reduction in the labeling time.

[0159] The face may comprise a thermoplastic film having an asymmetric orientation. Asymmetric orientation means that the degree of orientation in the two orientation directions is different. Without annealing and / or under controlled heat treatment, the biaxial asymmetric orientation can affect the provision of a predetermined and non-uniform shrinkage ability to the face, thereby further improving the washability of the label.

[0160] The face may comprise a biaxially oriented thermoplastic film having an asymmetric orientation. The asymmetric shrinkage of the biaxially oriented thermoplastic film affects the performance of the label in both the labeling stage and the subsequent stage of removing the label from the surface of the labeled article. The asymmetric orientation can affect the effective removability of the label from the attached surface. The asymmetric shrinkage and the higher shrinkage rate in the transverse direction can also have an effect on enhancing the separation of the label adhered to a cylindrical bottle shape with a convex surface.

[0161] At 65 °C, the thermoplastic film of the face may exhibit a shrinkage rate of at least 20% in the transverse direction. Alternatively or additionally, the thermoplastic film of the face may exhibit a shrinkage rate of at least 20% in the machine direction at 65 °C. In one embodiment, at 65 °C, the thermoplastic film of the face exhibits a shrinkage rate between 20% and 80% in the machine direction and / or the transverse direction of the film. The shrinkage rate of the thermoplastic film of the face can affect the ability of the label to be washed off the labeled surface. In addition, the shrinkage rate can have an effect on the more efficient and rapid removal of the label from the surface of the attached article during the washing process. The shrinkage of the thermoplastic film applies stress, such as shrinkage tension, to the adhesive bond between the adhesive layer and the surface of the labeled article, thereby enhancing or enabling the removal of the label from the labeled surface.

[0162] At temperatures below 55 °C, preferably below 60 °C, the shrinkage rate of the thermoplastic film of the face in both directions (MD / CD) can be less than 5%, preferably less than 2%, for example between 0 and 5%, or between 0.1 and 2%. At temperatures below 55 °C, preferably below 60 °C, the low shrinkage rate can be effective in avoiding the undesired shrinkage of the label during storage or label conversion steps (such as during printing). In addition, if the shrinkable thermoplastic film has a very low shrinkage rate at temperatures below 55 °C, preferably below 60 °C, the shrinkage rate of the film can remain at substantially the same level until the washing process.

[0163] The thermoplastic film of the face may be transparent or clear. From an optical perspective, high label transparency may be preferred. For example, in applications where the object below the label (i.e., the surface of the bottle) should be visible through the label. The haze of the film may be less than 25%, or less than 10%, such as 2 - 6%, or 4 - 5%. The haze is tested according to standard ASTM D1003. When the label haze is low, the adhesive is also preferably clear or transparent.

[0164] Alternatively, one or more of the thermoplastic films of the face may be, for example, opaque and / or white. In this embodiment, the face may contain additives, such as pigments, to provide the desired color. In a multilayer film structure, the wash-off additive may be included in one or more of the layers.

[0165] As described, the film of the face comprises a thermoplastic polymer. The thermoplastic film may comprise, for example, at least one of the following: polyethylene terephthalate PET, polyvinyl chloride PVC, polystyrene PS, polypropylene PP, polyethylene PE, polylactic acid PLA, and cyclic olefin copolymer COC.

[0166] Polystyrene (PS) is a synthetic aromatic polymer made from the monomer styrene. Polystyrene is a thermoplastic polymer with a glass transition temperature of about 100 °C. It is solid at room temperature but flows if heated above the glass transition temperature. It becomes rigid again after cooling. This temperature behavior is used for extrusion, as well as for molding and vacuum forming, because it can be cast into molds with fine details.

[0167] Examples of polymers derived from polystyrene include: styrene block copolymers such as SBS, SIS, SEBS, SEPS, SIBS, SEP, SEEPS, etc. One example discloses the coextrusion of a GPPS / SBC copolymer layer with an olefin elastomer or plastomer. The resulting film will have a density of less than 1.0 g / cm 3 of density.

[0168] Polylactide (PLA) is beneficial due to its environmental properties such as being developed from renewable materials and biodegradability. Polylactide is a biodegradable, thermoplastic, aliphatic polyester derived from lactic acid obtained from renewable or non-renewable resources such as corn starch-based lactic acid. Polylactide initially has a partially crystalline structure containing crystalline and amorphous regions. Polylactide can also be completely amorphous. Compared with many thermoplastics, polylactide can be processed into fibers, films or other products manufactured by conventional melt processing techniques in a similar manner. Due to the chiral nature of lactic acid and different cyclic diesters, lactide stereoisomers, there are several different forms of polylactide, such as the homopolymer PLLA of L-lactide, and the stereocopolymer P(L / D)LA of L-lactide and D-lactide, or the stereocopolymer P(L / DL)LA of L-lactide and DL-lactide.

[0169] Cyclic olefin copolymers are amorphous polymers based on different types of cyclic monomers. Cyclic olefin polymers and copolymers are produced by chain (co)polymerization of cyclic monomers. Such polymer materials using a single type of monomer are called cyclic olefin polymers (COP).

[0170] Cyclic olefin polymers can be extruded using a casting or blown film device. Cyclic olefin polymers can also be used as modifiers for single-layer or multi-layer films to provide properties that cannot be provided by a base resin such as polyethylene. Examples of favorable COC properties include: thermoformability, shrinkage, deadfold, tear, enhanced rigidity, heat resistance, and higher moisture barrier. The optical properties of cyclic olefin polymers [such as transparency, low birefringence, high Abbe number, and high heat resistance] are favorable and are similar to glass in many respects. Cyclic olefin polymers generally have a wide glass transition temperature range in the range of about 80 - 180 °C. Examples of cyclic olefins include cyclobutene, cyclopentene, norbornene, vinylcyclohexane, and dicyclopentadiene.

[0171] The thermoplastic film of the face may include a polyester film such as polyethylene terephthalate PET film. PET can be modified. The modified PET can be PETG modified with ethylene glycol. In PETG, the ethylene glycol units of the polymer backbone can be replaced with, for example, cyclohexanedimethanol CHDM and / or neopentyl glycol NPG. Thus, in one example, the thermoplastic film of the face comprises polyethylene terephthalate glycol-modified PETG.

[0172] The ethylene glycol-modified polyethylene terephthalate PETG has technical effects. The ethylene glycol-modified polyethylene terephthalate PETG can affect the flexibility of the film. It can also affect the film's ability to be oriented. In addition, the modification can have an impact on reducing the brittleness of the thermoplastic film of the face. PETG can have an impact on avoiding stress whitening of the thermoplastic film, for example, during label application. It can also affect the transparency and clarity of the thermoplastic film.

[0173] In an advantageous embodiment, the thermoplastic film of the face can comprise a polypropylene and / or polyethylene film.

[0174] Polypropylene (PP) is a thermoplastic polymer with a glass transition temperature of about -20 °C (atactic polypropylene) or about 0 °C (isotactic polypropylene). Examples of suitable polypropylenes or polymers derived from polypropylene include PP homopolymers, random PP copolymers, PP block copolymers, PP terpolymers, PP elastomers, and PP plastomers.

[0175] Polyethylene (PE) is a thermoplastic polymer that can be classified into several different categories according to density and branching. Examples of such categories include: ultra-high molecular weight polyethylene (UHMWPE), ultra-low molecular weight polyethylene (ULMWPE or PE-WAX), high molecular weight polyethylene (HMWPE), high density polyethylene (HDPE), high density crosslinked polyethylene (HDXLPE), crosslinked polyethylene (PEX or XLPE), medium density polyethylene (MDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), very low density polyethylene (VLDPE), and chlorinated polyethylene (CPE). The melting point and glass transition temperature can vary depending on the type of polyethylene. For medium density polyethylene and high density polyethylene, the melting point is typically in the range of 120 - 180 °C, and for average low density polyethylene, the melting point is in the range of 105 - 115 °C. The glass transition temperature of LDPE is about -125 °C.

[0176] The face can comprise, for example: oriented polypropylene film (which can be a biaxially oriented film) and / or oriented polyethylene film (which can be a biaxially oriented film). The polyolefin film can improve the ease of handling the film. In addition, polypropylene can be less rigid than, for example, polyester. The reduced rigidity can reduce sagging or fluttering on curved bottles. Some containers may require such flexibility. In addition, biaxially oriented polypropylene and polyethylene films can have a density of less than 1.0 g / cm 3 resulting in the film floating during processing. Thus, during washing, PET flakes can sink while labels containing, for example, oriented polypropylene film can float.

[0177] Paper face

[0178] The face 1 may comprise paper or be made of paper. Compared with thermoplastic labels, labels comprising a paper-based face 1 are generally more environmentally friendly materials for labeling articles such as bottles.

[0179] A calender or supercalender may be used to calender the paper in order to obtain a high-density surface.

[0180] Preferably, for environmental reasons and to improve cost efficiency, the face 1 has only one layer of paper. Thus, the face 1 may comprise or consist of environmentally friendly materials. Therefore, paper labels are better for the environment compared to some other types of face materials.

[0181] The face 1 may comprise paper having natural fibers as its main raw material. Natural fibers refer to any plant material containing cellulose. The natural fibers are preferably wood-based natural fibers.

[0182] The wood-based natural fibers may be from softwood trees such as spruce, pine, fir, larch, douglas-fir or hemlock, and / or from hardwood trees such as birch, aspen, poplar, alder, eucalyptus or acacia, or from a mixture of softwood and hardwood.

[0183] The face 1 may comprise cellulose fibers from both hardwood and softwood. The technical effect of mixing hardwood and softwood is to improve the internal bond strength of the face 1. This can be particularly advantageous for paper labels, at least if the paper label is used as a direct thermal paper label.

[0184] The paper of the paper label is preferably so-called wood-free paper. Wood-free refers to chemical pulp such as kraft pulp. According to one embodiment, since the quality requirements of the face are high, the pulp used to manufacture the face does not contain any type of mechanical pulp. Thus, the face 1 may be wood-free paper comprising fibers from softwood and / or hardwood, for example.

[0185] The fiber content of the paper may be equal to or greater than 50 wt%, preferably at least 60 wt%, and more preferably at least 70 wt% in order to improve the strength of the paper label. In addition, increasing the content of natural fibers can reduce dusting of the paper label if the paper is cut, for example in an on-demand printer.

[0186] The face 1 may further comprise, for example, at least one filler, such as a mineral filler. The at least one filler may be selected from: clay, calcined clay, kaolin, natural ground calcium carbonate, precipitated calcium carbonate, talc, calcium sulfate, and titanium dioxide. The total amount of filler in the face 1 is preferably less than 10% by weight, more preferably less than 5% by weight, and most preferably less than 3% by weight, for example between 0.5 and 5% by weight, or between 0% and 3% by weight, based on the total dry weight of the face 1. The filler can reduce the cost of the manufactured product. In addition, since the filler can reduce the wet strength properties of the face, the filler can improve the recyclability of the paper label.

[0187] The mineral filler can also reduce the strength properties of the face 1. If the face 1 contains too much mineral filler, some properties of the face 1 can be impaired. Thus, in one example, the face 1 does not contain mineral filler.

[0188] The face 1 may comprise paper coated with one or more coatings. For the coated paper, a total coating weight of 1 to 12 g / m² (on one side or both sides) can be used. The coating layer may comprise at least one pigment selected from: clay, calcined clay, kaolin, natural ground calcium carbonate, precipitated calcium carbonate, talc, calcium sulfate, and titanium dioxide. In addition, the coating layer may comprise an adhesive. For environmental reasons and to improve the properties of the paper label, the adhesive may comprise starch and / or polyvinyl alcohol, or consist of starch and / or polyvinyl alcohol. 2 The face 1 comprising paper can be calendered (e.g., using a supercalender) to obtain a high-density surface.

[0189] The grammage of the face 1 is preferably at least 50 g / m²

[0190] and more preferably at least 60 g / m² 2 . Further, the grammage of the face 1 is preferably less than 85 g / m² 2 and more preferably equal to or less than 80 g / m² 2 . For example, the grammage can be between 50 g / m² 2 and 82 g / m² 2 or between 70 and 80 g / m² 2 . The grammage is particularly suitable for paper labels for on-demand printers and subsequently suitable for the washing process. The grammage can be measured according to standard ISO536. 2 The grammage is particularly suitable for paper labels for on-demand printers and subsequently suitable for the washing process. The grammage can be measured according to standard ISO536.

[0191] The face 1 may have a caliper in the range between 50 μm and 95 μm, preferably between 55 μm and 90 μm, more preferably between 60 μm and 85 μm, measured according to ISO534. If the face is too thin, the paper label may be difficult to handle. For example, if the face is too thin, the stiffness of the paper label may be too low, resulting in the paper label being too sloppy. As a result, the paper label may be difficult to manufacture, and / or the paper label may cause problems when used in the labeling process. However, a thinner face may be easier and faster to wash off from the article, thus enabling an efficient recycling process for the bottle.

[0192] To improve printability and / or provide a desired appearance, the top side of the paper label may have a smoothness (Beck) in the range of at least 350 sec to 550 sec, measured according to standard ISO5627. For example, a silicon layer on the top side of the face will make the paper label smooth. Thus, in one embodiment, the top side of the paper label may have a smoothness (Beck) equal to or greater than 1000 sec, measured according to standard ISO5627.

[0193] When measured according to standard ISO2469, the paper label may have a brightness (R457) higher than 85%. Thus, the paper label looks good. In addition, the high brightness can create a contrast between the symbols / letters. Therefore, if the letters include some machine-readable letters, these letters can be easily read due to the brightness. This is particularly advantageous when using the paper label for recyclable bottles.

[0194] When measured according to standard ISO2471, the paper label may have an opacity higher than 80%, for example between 80 and 90. Due to the opacity, the surface of the paper label is not too transparent for the machine to read. This is particularly advantageous when using the paper label for recyclable bottles.

[0195] When measured according to standard ISO1924 / 2, the tensile strength of the face 1 and / or the paper label in the machine direction may be higher than 40 N / 15 mm, preferably higher than 45 N / 15 mm. The technical effect is to improve the dimensional stability of the paper label. The improved dimensional stability has a positive impact on the manufacturing process, the printing process, and some washing processes.

[0196] When measured according to standard ISO1924 / 2, the tensile strength of the face 1 and / or the paper label in the cross direction may be higher than 10 N / 15 mm. The technical effect is to improve the dimensional stability of the paper label. The improved dimensional stability has a positive impact on the manufacturing process, the printing process, and some washing processes.

[0197] In a preferred embodiment, a paper label is attached to a bottle, and the label and the labeled bottle have such densities that one has a density greater than that of water and the other has a density less than that of water. The technical effect is to improve the recyclability of the paper label.

[0198] In one embodiment, the density of the paper label is adjusted to an overall average density greater than 1.0 g / cm 3 . The technical effect is to provide a label that sinks during the washing process. For example, in the case of PP and HDPE bottles (where the recycling method includes crushing or shredding the plastic bottles), the pieces of the bottle float in water while the paper label will sink, thus allowing for the effective collection and recycling of the PP and HDPE pieces. Therefore, as the shredded plastic bottle pieces float, this allows for the easy separation of the label from the bottle, especially when using the overall average density together with a wash-off adhesive, allowing the PSA to be efficiently separated from the bottle in water at 40°C. A further technical effect is to provide a particularly environmentally friendly product where the plastic and cellulose fibers can be collected separately.

[0199] The paper label can be recycled in a fiber loss system (where the paper is completely broken into small pieces) or in a non-fiber loss system (where the paper does not break under wet conditions). Preferably, the paper label completely breaks into the washing water.

[0200] The paper can be manipulated by the washing water. For example, the paper can be recycled in a system comprising a cyclone cleaning device. The cyclone cleaning device can be used to remove the paper label from the system.

[0201] Therefore, the paper label can be a particularly environmentally friendly wash-off label.

[0202] Direct thermal label

[0203] The label according to the present application can be a direct thermal label, such as a direct thermal linerless paper label. The technical effect of this embodiment is to provide a label with thermal printability while improving the washability of the label.

[0204] The face 1 of the direct thermal paper label has at least two layers. The face 1 can comprise, or consist of:

[0205] - paper,

[0206] - a direct thermal coating layer,

[0207] - optionally, an intermediate layer that remains between the direct thermal coating layer and the paper, and

[0208] - Preferably, a top coating on the direct thermal coating layer.

[0209] Thus, the label can be a direct thermal paper label, such as a direct thermal linerless paper label, which comprises or consists of the following:

[0210] - A face 1, which comprises

[0211] - Paper,

[0212] - A direct thermal printable coating,

[0213] - Optionally, a top coating on the direct thermal printable coating, and

[0214] - Optionally, an intermediate layer disposed between the base layer and the direct thermal printable coating,

[0215] - Optionally, a release coating on the face 1, and

[0216] - A pressure - sensitive adhesive coating.

[0217] If label 2 is a direct thermal label, the face 1 can have a static sensitivity at below 100 °C, preferably between 75 °C and 95 °C. The static sensitivity and dynamic sensitivity need to be low enough so that the product does not darken before printing (e.g., during transportation). However, the static and dynamic sensitivities should be high enough such that the label is thermally printable.

[0218] As described, the face 1 can further comprise a top coating on the direct thermal printable coating. The top coating preferably has a grammage between 0.5 g / m 2 and 3 g / m 2 . The top coating can protect the top surface of the face 1 and / or the print from rubbing or other external stresses.

[0219] If used, the top coating can comprise at least one of the following: starch, polyvinyl alcohol (PVA), latex, and wax. Preferably, the top coating comprises polyvinyl alcohol (PVA) and / or wax. These coatings can provide improved protection for the direct thermal printable coating. In addition, wax can improve the friction property of the paper label. The top coating can further help reduce dusting of the paper label during use.

[0220] The direct thermal printability coating can be set to provide thermal printability of the face 1. The direct thermal printability coating is set to form a thermally sensitive, reactive layer that changes color during thermal printing. The thermal coating may include a reactive component. The thermal coating may include a matrix. The matrix may include a dye and a developer.

[0221] Preferably, in order to improve the printing quality economically and efficiently, the direct thermal printability coating has a grammage in the range between 1 g / m 2 and 5 g / m 2 .

[0222] Typically, the solid-state thermal coating matrix is heated by a thermal print head to a temperature higher than its activation point and / or melting point. The dye of the thermal coating may include a leuco type dye. The leuco type dye is set to react with an acid and turn into a colored form.

[0223] The thermal coating may include:

[0224] - a dye,

[0225] - a developer,

[0226] - a sensitizer,

[0227] - an adhesive, and

[0228] - a stabilizer.

[0229] During thermal printing, the developer may be set to co-react with the dye at a temperature higher than the activation temperature. The reaction between the dye and the developer is set to trigger color formation. The developer may include a sulfonylurea, a zinc salt of a substituted salicylic acid, or a phenol such as bisphenol S (BPS). The thermal coating may preferably be free of BPA, free of bisphenol (BP), and / or free of phenol in order to improve chemical safety.

[0230] The sensitizer may be used in the thermal coating in order to lower the melting point of the dye and / or the developer. The dye and the developer are set to react when heated to a temperature higher than the melting point of the thermal coating matrix. The melting point of the matrix may depend on the melting point values of its components. The thermal threshold of the thermal coating is the melting point of the component of the thermal coating that has the lowest melting point. The sensitizer of the thermal coating may be set to lower the melting point of the dye and / or the developer. This has the effects of demonstrating melting point accuracy, and / or optimizing the color change temperature, and / or promoting the mixing of the dye and the developer.

[0231] Optionally, the thermosensitive coating may contain a stabilizer. Dyes in thermally sensitive paper may be unstable and tend to revert to their original colorless crystalline form. Thermosensitive paper may be sensitive to external conditions such as hot and humid environments. To stabilize the metastable glass formed by the colorless dye, developer, and sensitizer, a stabilizer can be added to the mixture. The stabilizer can affect the inhibition of recrystallization of the dye and developer and / or stabilize the printing.

[0232] The adhesive of the thermosensitive coating may have the effect of promoting the adhesion of the thermosensitive coating to the base substrate or pre - coat. The adhesive may contain double bonds. The adhesive may contain polyvinyl alcohol (PVA) or latex, such as styrene - butadiene latex (SB) or styrene - acrylic latex (SA).

[0233] The sensitivity of the thermosensitive coating refers to the degree to which it responds to a given amount of heat or energy. Sensitivity is a decisive factor in selecting a suitable thermosensitive coating or thermosensitive paper. It can be depicted in a graph plotting the image density or optical density (OD) against the heat or energy transferred. Optical density is a measure of the relationship between incident light and reflected light. An optical density of approximately 1.1 is typically considered completely black to the human eye. Thus, lower optical densities correspond to different shades of gray. The thermosensitive coating and thermosensitive paper are typically characterized using static and dynamic sensitivity.

[0234] Static sensitivity indicates the temperature at which the thermosensitive paper begins to form an image (i.e., change color). Thermosensitive paper with low static sensitivity only begins to form an image at high temperatures (e.g., above 90 °C). On the other hand, thermosensitive paper with medium static sensitivity begins to form an image at lower temperatures (e.g., between 80 °C and 90 °C). Thermosensitive paper with high static sensitivity begins to react even at lower temperatures (e.g., 65 - 80 °C, or at 70 - 80 °C).

[0235] Therefore, if the label is a direct thermosensitive wash - off label, the face 1 preferably has a static sensitivity below 100 °C, more preferably in the range between 75 °C and 95 °C.

[0236] Release coating layer on the face

[0237] Label 2 may contain a release coating layer on top of face 1, i.e., on the second surface of face 1. The release coating layer on top of the face is an optional layer and is particularly advantageous for linerless labels.

[0238] If label 2 is a direct thermosensitive label, the release coating layer may be located on top of the direct thermosensitive coating. The thermosensitive printing of the label can be achieved through the release coating layer.

[0239] In one embodiment, label 2 is a linerless label. Thus, label 2, which has a pressure-sensitive adhesive on one side (the bottom side) and a release coating on the other side (the top), can self-wind around itself without a tendency for adjacent layers of the label web to interfere with each other. Due to the release coating on the top of the face, the adhesion can be low enough that the adhesive layer can easily release from the face 1 material when the linerless label roll is unwound.

[0240] The release coating can be a silicone-based or non-silicone-based release coating. Preferably, the release coating comprises a silicone-based release coating or consists of a silicone-based release coating.

[0241] Non-thermocurable release coatings, such as UV-curable silicones, are preferred, at least when the label is a direct thermal label. The technical effect is that the curing of these layers does not heat the heat-sensitive material of the direct thermal label. Thus, the release coating can be a UV-curable silicone, which has the benefit of being curable on top of the thermosensitive face 1 without heating.

[0242] In some embodiments, a further technical effect of the release coating on the top of the face is to reduce friction with the printhead of the printer and to minimize wear of the printhead. Further, since the friction of the printhead is reduced and wear is minimized, the printing quality of the label can be improved.

[0243] In addition, unexpectedly, during experimental testing, the silicone-based release coating did not cause problems during the washing process.

[0244] Adhesive composition

[0245] The adhesive provides adhesion, i.e., adheres or bonds the label to the surface of an object. The adhesive layer of the label should have adhesive properties, i.e., tack (stickiness), in order to adhere to the object during the labeling process. Tack is the property of an adhesive that allows an immediate bond to form upon contact with another surface. Tack is required when attaching the label to an object. The optimal adhesion between two materials depends, for example, on the wetting and surface energy of the materials. In order for the adhesive to wet the surface, the surface tension of the adhesive must be lower than or equal to the surface tension of the article to be labeled. If the surface tension of the adhesive is lower than the surface tension of the article, good wetting and increased adhesion result. Inherently low surface energy materials, such as polyethylene and polypropylene, may be difficult to bond without special surface treatment. Their surface energy levels can be in the range of 30 to 32 dynes / cm.

[0246] Acrylic emulsion adhesives are acrylic polymers and copolymers polymerized in water. These aqueous adhesives are applied to a substrate, and then the water is evaporated by passing the coated substrate through a drying tunnel.

[0247] The label contains a modified adhesive composition, which contains an acrylic adhesive and a wash-off additive.

[0248] The wash-off additive added to the acrylic adhesive can be in the form of an aqueous dispersion. The acrylic adhesive composition containing the wash-off additive can be prepared by blending the acrylic adhesive and the wash-off additive.

[0249] The amount of the wash-off additive is at least 4% by weight, calculated based on the total dry weight of the acrylic adhesive. To improve the efficiency of the additive, the amount of the wash-off additive can be at least 5% by weight, preferably at least 10% by weight, more preferably at least 12% by weight, and most preferably at least 15% by weight. As the amount of the wash-off additive increases up to at least 20% by weight, the effect of the wash-off additive on the washability of the label can be improved.

[0250] When the amount of the wash-off additive does not exceed 25% by weight, the acrylic adhesive can be the most efficient. Therefore, the amount of the wash-off additive can be equal to or less than 25% by weight, preferably equal to or less than 20% by weight, and most preferably equal to or less than 18% by weight, calculated based on the total dry weight of the adhesive. In an advantageous example, the amount of the wash-off additive is 10% to 20% by weight, calculated based on the total dry weight of the adhesive.

[0251] Due to the wash-off additive in the acrylic adhesive, the washability of the PSA can be significantly improved.

[0252] As described, the adhesive according to the present application is an acrylic adhesive. Acrylic resins are a class of synthetic polymers belonging to the thermoplastic resin series. The technical effects include providing strong and durable adhesion at normal temperature and ordinary conditions. Acrylic adhesives are based on acrylic polymers, also known as acrylate polymers. The acrylate monomers used to form acrylate polymers are based on the structure of acrylic acid, which contains a vinyl group and a carboxylic acid end. Acrylic polymers are characteristically adhesive and can be used as pressure-sensitive adhesives without any modification. Further technical effects include good aging and ultraviolet resistance properties. They are polar in nature and thus provide good adhesion to polar substrates.

[0253] The acrylic adhesive may be in the form of an acrylate aqueous dispersion, with a solids content in the range between 40% and 60%, preferably in the range between 50% and 60%. The technical effect of the solids content is to provide a simpler drying process. Another technical effect is that, due to the higher solids content, less energy is required for the drying process. Therefore, a higher solids content is an environmentally friendly solution. A further technical effect is to reduce costs, such as conversion costs and transportation costs.

[0254] Preferably, the acrylic adhesive coating comprises:

[0255] - butyl acrylate, or

[0256] - 2-ethylhexyl acrylate, or

[0257] - butyl acrylate and 2-ethylhexyl acrylate.

[0258] The total content of butyl acrylate and 2-hydroxyethyl acrylate may be at least 50% by weight, more preferably at least 70% by weight, more preferably at least 80% by weight, and most preferably at least 85% by weight, calculated based on the dry weight of the acrylic adhesive. These acrylic adhesives may be particularly advantageous for labels.

[0259] The acrylic adhesive coating may comprise:

[0260] - rosin acid, and / or

[0261] - a copolymer of vinyl acetate and ethylene (VAE).

[0262] Rosin acid is an organic acid known to those skilled in the art.

[0263] The copolymer of vinyl acetate and ethylene (VAE) is a vinyl acetate-ethylene copolymer known to those skilled in the art. The technical effect is to provide improved properties for the PSA, such as improved tack and adhesion properties for the acrylic adhesive.

[0264] In one embodiment, the acrylic adhesive comprises at least 80% by weight (based on dry weight) of 2-ethylhexyl acrylate, calculated based on the dry weight of the acrylic adhesive. This type of adhesive in the adhesive may be particularly useful. Further, the acrylate dispersion may not have a strong impact on the color of the layer, and thus, the visual appearance can be easily controlled.

[0265] The acrylic adhesive may further comprise one or more crosslinking agents. The one or more crosslinking agents may be selected from: allyl methacrylate (AMA), ethylene glycol dimethacrylate (eGDMA), triethylene glycol dimethacrylate (TRGDMA), polyethylene glycol 200 dimethacrylate (PeG200DMA), 1,3 - butanediol dimethacrylate (1,3 - BDDMA), 1,4 - butanediol dimethacrylate (1,4 - BDDMA), 1,6 - hexanediol dimethacrylate (1,6 - HDDMA), glycerol dimethacrylate (GDMA), trimethylolpropane trimethacrylate (TMPTMA), and diurethane dimethacrylate (HEMATMDI).

[0266] The particle size (nm) of the acrylic adhesive composition may be in the range of: 100 nm to 800 nm, preferably 120 nm to 500 nm, more preferably 140 nm to 400 nm, and most preferably 150 nm to 300 nm, measured as the average particle diameter. The particle size can affect the behavior of the acrylic adhesive composition. In the case of the range of 100 to 800 nm, and particularly in the most desired range of 150 nm to 300 nm, the properties of the acrylic adhesive (such as the solids content and viscosity level) can be easily adjusted to the desired level.

[0267] The polymer gel content of the acrylic adhesive composition can be used to determine the crosslinking level of the adhesive. The polymer gel content of the acrylic adhesive composition can be at least 10%, such as in the range of 20% to 90%, preferably 45% to 85%, more preferably 55% to 80%, and most preferably 60% to 75%, or 65% to 75%. Due to the polymer gel content, and particularly because of the preferred range, the adhesive properties can be controlled to an improved level. An excessively high gel content can reduce the adhesive properties, while an excessively low gel content can overly increase the adhesive properties.

[0268] In an advantageous embodiment, the adhesive further comprises 0.1 to 0.5% by weight (dry weight), preferably 0.2 to 0.4% by weight (dry weight) of a non - ionic biodegradable surfactant. When used together with the wash - off additive, adding the non - ionic biodegradable surfactant can be an environmentally friendly way to improve washability.

[0269] To improve the washability of the acrylic adhesive, the acrylic adhesive according to the present application comprises a wash - off additive, and the wash - off additive comprises a grafted rosin ester. The wash - off additive may comprise an aqueous phase and resin particles dispersed in the aqueous phase.

[0270] The resin particles of the washing additive may comprise a resinous material selected from hydrocarbon resins, alkyd resins, polyamide resins, rosin resins, and mixtures thereof. Preferably, the resinous material comprises a rosin resin or is a rosin resin. In one embodiment, the amount of the rosin resin is at least 50% by weight, preferably at least 65% by weight, such as at least 80% by weight, and more preferably at least 90% by weight, such as 100% by weight, based on the resinous material. The resinous material, and particularly the rosin resin, can improve the performance of the additive.

[0271] In the washing additive, the amount of the grafted rosin ester relative to the resinous material may be at least 1% by weight, for example about 1% by weight to about 8% by weight, preferably about 2% by weight to about 6% by weight, such as about 3% by weight to about 5% by weight. Thus, the effect of the washing additive in the acrylic adhesive can be improved.

[0272] The dispersion may further comprise, for example, an anionic emulsifier, preferably in an amount of 0.1% by weight to 3% by weight.

[0273] In the washing additive, the total amount of the resinous material, the grafted rosin ester, the optional anionic emulsifier, and water may be at least 95% by weight, preferably at least 97% by weight, such as at least 98% by weight, and more preferably at least 99% by weight, such as 100% by weight, based on the total weight of the washing additive.

[0274] In one embodiment, the resin particles of the washing additive have an average particle size d50 of less than 1.2 microns, preferably less than 0.9 microns, where d50 means the average particle size of the 50% by weight portion of the particles starting from the smallest particles.

[0275] Thus, as described, the washing additive may be an aqueous dispersion comprising a grafted rosin ester. The grafted rosin ester according to the present application is a rosin ester grafted with a capped polyalkylene glycol, where the capped polyalkylene glycol is a poly(alkylene glycol) alkyl ether.

[0276] The polyalkylene glycol may be selected from C2-C5 polyalkylene glycols and mixtures thereof. In a preferred embodiment, the polyalkylene glycol is polyethylene glycol or contains polyethylene glycol. The polyethylene glycol may be particularly suitable for improving the washability of the washing additive.

[0277] The alkyl ether may have 1 to 18 carbon atoms, preferably 1 to 4 carbon atoms. Most preferably, in order to improve the washability of the additive, the alkyl ether is a methyl ether.

[0278] Thus, in an advantageous embodiment, the end-capped polyalkylene glycol is a methyl ether-capped polyethylene glycol. This can particularly improve the washability of labels containing acrylic adhesives during low-temperature washing processes. Further, by using a wash-off additive comprising the rosin ester grafted with the end-capped polyalkylene glycol (wherein the end-capped polyalkylene glycol is the methyl ether-capped polyethylene glycol), the PSA can be kept attached to the face at all times.

[0279] Thus, in an advantageous embodiment, the wash-off additive comprises a rosin ester grafted with a methyl ether-capped polyethylene glycol. Such additives can significantly improve the washability of the labels.

[0280] The end-capped polyalkylene glycol may have an Mw in the range between 1000 and 10000, preferably in the range of 1000 to 8000. The average molecular weight of the end-capped polyalkylene glycol can be determined, for example, by hydroxyl value analysis.

[0281] The molar ratio between the rosin ester and the end-capped polyalkylene glycol can be from 0.05:1 to 1:1, preferably from 0.2:1 to 1:1, more preferably from 0.4:1 to 1:1, and most preferably from 0.7:1 to 0.9:1. The molar ratio can improve the washability of the labels.

[0282] Unexpectedly, by using a wash-off additive comprising a grafted rosin ester in an acrylic adhesive, the washability of the labels can be significantly improved. In test trials, such an effect was not seen with conventional rosin ester surfactants, nor with conventional polyalkylene glycols such as polyethylene glycol.

[0283] The acrylic adhesive comprising a dispersion of acrylates and the wash-off additive can be extremely sensitive to washing conditions including low temperatures (e.g., 40 °C to 75 °C). Further, the adhesion of the adhesive to the labeled article can decrease more than the adhesion to the face, such that the adhesive can remain attached to the face.

[0284] The adhesive comprising the wash-off additive can be an environmentally friendly solution and can be used with, for example, food materials. Further, compared to some other pressure-sensitive adhesives, water-based acrylic adhesives can have a longer open time, and thus, if desired, labels comprising a water-based acrylic PSA can be removed after a few seconds or minutes.

[0285] Pressure-sensitive adhesive layer

[0286] The label can be fixed to the surface of an article (product) 100 by an adhesive layer 4, thereby forming a labeled article 101. The label can comprise an adhesive layer sensitive to washing conditions.

[0287] A washing-condition-sensitive adhesive refers to an adhesive in which the adhesion of the adhesive decreases under washing conditions. The washing conditions generally include water, optionally alkaline conditions, and increased temperature. The increased temperature can be, for example, from 40 °C to 75 °C.

[0288] The alkaline conditions refer to an aqueous solution containing an alkaline reagent such as NaOH, KOH, or a combination thereof. The most common alkaline reagent is probably sodium hydroxide (NaOH), also known as caustic soda. The alkaline conditions (i.e., the alkaline liquid) generally contain about 0.5 - 10% or 1 - 4%, for example about 1 - 2% (by weight) of the alkaline reagent.

[0289] Preferably, a film-like label comprising a film-like face is washed under alkaline conditions at 65 - 75 °C, while a paper label comprising a paper face can be washed at 40 °C using water without using the alkaline reagent.

[0290] The adhesive layer of the label should have suitable adhesion [i.e., tack (stickiness)] to stick to an object during the labeling process. Tack is the property of an adhesive that allows an immediate bond to form when in contact with another surface. This tack is required at the moment the label adheres to the object. The optimal adhesion between two materials depends on, for example, the wettability and surface energy of the materials.

[0291] The adhesive layer 4 can be a continuous coating that covers 100% of the face surface (referring to the first surface of the face). Alternatively, the adhesive layer 4 can be applied discontinuously as dots or bands covering less than 100% of the first surface of the face. For example, the adhesive can cover 10 to 90% of the total area of the first surface of the face. A reduction in the amount of the adhesive can have an impact on: during the washing process, reducing the time required to subsequently remove the label from the surface of the attached object. Thus, in an advantageous embodiment, the adhesive layer 4 covers less than 90%, more preferably less than 80% of the first surface of the face.

[0292] The adhesive coating can consist of one layer. The technical effect is that the coating process can be simplified.

[0293] Alternatively, the adhesive coating can have a multi-layer structure, including two or more layers, preferably 2 to 4 layers, such as 3 or 4 layers. Preferably, if the adhesive coating has a multi-layer structure, at least two layers have different adhesive compositions from each other. The technical effect of the multi-layer structure is to control the washability of the label during recycling, especially the anchorage and delamination properties of the label.

[0294] The adhesive layer may have a total thickness in the range of about 5 - 40 μm, or in the range of about 8 - 20 μm. To further improve the efficiency of washing, the total thickness of the adhesive layer may be in the range of about 5 - 15 μm or 5 - 12 μm.

[0295] The amount of the adhesive in the label (by dry weight) may be in the range of about 5 - 40 g / m 2 、or 8 - 20 g / m 2 In order to improve the efficiency of washing, the amount of the adhesive may preferably be less than 20 gsm, such as equal to or less than 15 g / m 2 . In an advantageous embodiment, the total amount of PSA in the label is between 5 and 20 g / m 2 or between 5 and 15 g / m 2 .

[0296] The label contains the acrylic pressure - sensitive adhesive (PSA). A label with a PSA layer can adhere to most surfaces through the adhesive layer without using a secondary agent (such as a solvent) or heat to enhance adhesion.

[0297] Generally, the pressure - sensitive adhesives can be divided into the following groups: water - borne PSA, solvent - based PSA, and solid PSA. Solid PSA melts during application to the surface to be coated and is also called hot - melt PSA.

[0298] As described, the adhesive (PSA) according to the present application is acrylic - based. Due to the acrylic - based adhesive, the adhesive can remain mostly adhered to the face 1 during the washing process.

[0299] Relative to other types of PSA, the water - based acrylic pressure - sensitive wash - off adhesive can have multiple advantages. For example, due to the water - based acrylic adhesive, the adhesiveness of the product can be at an improved level. In addition, the water - based acrylic adhesive can be environmentally friendly. Further, the water - based acrylic adhesive can be efficiently blended with the wash - off additives. Further, the wash - off label can be a particularly environmentally friendly product.

[0300] The pressure - sensitive adhesive according to the present application can exhibit a reduction in adhesion under washing conditions, such as for film - like labels, using aqueous alkaline conditions at a temperature of 65 - 75 °C, or for paper labels, using aqueous conditions at 40 °C.

[0301] Release liner

[0302] Reference Figure 2, the label 2 may include a release liner 5. The release liner 5 is an optional feature.

[0303] The release liner 5 has a substrate 7, on which a release coating layer 6, such as silicone, is applied.

[0304] The term "release liner" refers to a structure that includes a layer of backing material as the substrate and a release coating layer on the surface of the substrate. In other words, the backing material is typically coated with a thin layer of a release agent (such as silicone). The substrate of the release liner can be a paper-based substrate or a film-based substrate. The release coating layer provides a non-adherent surface, that is, low adhesion and release effects on the adhesive layer. The release liner protects the adhesive layer during transportation and storage. It further allows the effective handling of each label after die-cutting the label and peeling the surrounding matrix until the moment when each label is dispensed on the labeling line.

[0305] When labeling, the release liner is removed and discarded, and the label is attached to the surface to be labeled through the adhesive layer. Therefore, the release liner of the label laminate serves one or more useful functions: it serves as a carrier sheet on which the adhesive can be coated; it protects the adhesive layer during storage and transportation; it provides support for the label during die-cutting and printing, and finally separates from the adhesive without damage.

[0306] The face 1 and the release liner are usually laminated together with an adhesive layer therebetween, and this laminated structure is called a label laminate.

[0307] If the label is a linerless label without a release liner, preferably the label has a release coating layer (such as a silicone layer) on the top of the face 1 (i.e., the second surface of the face).

[0308] Conventional silicone release coating systems consist of: reactive silicone compounds, crosslinking agents, catalysts, and optionally inhibitors. The silicone coating composition can be solvent-based, emulsion-based, or solventless (100% solid composition). The silicone content can be less than 2 g / m 2 , less than 1.5 g / m 2 , or less than 1 g / m 2 (dry weight). The amount of silicone can be at least 0.01, at least 0.02, or at least 0.1 g / m 2 . The amount of silicone can be between 0.4 and 1.5 g / m 2 , or between 0.6 and 1 g / m 2 , for example 1 g / m 2 .

[0309] Article

[0310] One embodiment provides a combination of a label and an article. The article can be a package. In an advantageous embodiment, the article is a beverage bottle.

[0311] The label can be in the form of a continuous label web having a plurality of individual labels wound into a roll. An automatic label dispenser can be configured to separate each label from the label web and deliver the label onto the surface of a product to be labeled.

[0312] Labels can be used for various labeling applications and end-use fields, such as beverage labeling, food labeling, home and personal care product labeling, and industrial product labeling. The surface of the labeled article can be based on, for example, plastic, glass, metal, or paper. The labeled article can be, for example, a container such as a bottle, a jar, a canister, a can, a tin, etc. The label can also be applied to semi-rigid or flexible packaging for, for example, packaged food.

[0313] An advantageous embodiment provides the use of the label for labeling a beverage bottle. Examples of the beverage bottle include: a glass bottle, a metal bottle, a polyethylene terephthalate (PET) bottle, and a bottle made of polyolefin [such as high density polyethylene (HDPE) and polypropylene (PP)].

[0314] The label can completely or partially surround the article to be labeled, such as a beverage bottle. The beverage bottle is preferably a polyolefin bottle, a polyethylene terephthalate (PET) bottle, or a glass bottle. Most preferably, the beverage bottle is a polyolefin bottle or a polyethylene terephthalate (PET) bottle. The beverage bottle can be a plastic bottle that exhibits heat shrinkage during washing.

[0315] In an advantageous embodiment, the label according to the present application is attached to the surface of a polyethylene terephthalate bottle or a polyolefin bottle. For example, it is known that a PET bottle is a thin bottle that shrinks at high temperatures and will break during washing.

[0316] Preferably, the label is attached to the bottle, and the label and the labeled bottle have such densities that one has a density greater than water and the other has a density less than water. The technical effect is to improve the recyclability of the label.

[0317] Removing the label during the recycling process

[0318] An adhesive label can be removed by washing the label off the surface of the object to which it is attached. The object can be a beverage bottle. The beverage bottle can be a plastic bottle that exhibits heat shrinkage during washing.

[0319] Tagged bottles are typically reused or recycled several times. Therefore, it is necessary to improve the label and the face structure in order to achieve an efficient and cost-effective recycling process for tagged objects.

[0320] Labels designed for this purpose are called wash-off labels. The wash-off labels are a type of label with specific properties. For example, the wash-off labels are different from repositionable labels, removable labels, and resealable labels.

[0321] Since polymeric labels (i.e., film labels) do not have the water permeability of paper labels, it may be more challenging to completely remove them using existing washing processes. Therefore, the washing conditions for polymeric labels and paper labels may be different, as described in the specification.

[0322] During the washing process, the label detaches from the tagged object (e.g., from the surface of a bottle). During the washing process, the label is exposed to a heated washing liquid. Under the influence of the washing conditions, the adhesive layer can at least partially lose its adhesion, thereby enabling the label to be removed from the surface of the tagged object and / or enhancing the removal of the label from the surface of the tagged object.

[0323] In one example, the adhesive layer may not dissolve in the washing liquid. Instead, after the label is removed from the object surface, the adhesive layer may adhere to the face. The technical effect is that the life of the washing solution can be extended.

[0324] As described, the label may comprise a shrinkable thermoplastic film. The technical effect is that the shrinkable thermoplastic film can provide a shrinkage force that weakens the adhesion of the adhesive layer, thereby causing the adhesive label to detach from the surface of the attached object during a washing process involving a heated aqueous washing solution.

[0325] Conventional washing conditions for recyclable containers (such as glass containers) may include in an aqueous solution at a temperature above 77 °C. For polyester or plastic containers, the conventional washing temperature used to be even about 80 °C.

[0326] As described, paper labels may already have improved washability in water at 40 °C, while film labels may already have improved washability at 65 °C. Therefore, due to the labels according to the present application, the washability of the labels can be improved, such that compared to conventional wash-off labels, the washing of the labels shows superior results.

[0327] Peel adhesion can be expressed as a peel value at a 180° angle, determined according to this specification. In one embodiment, the peel adhesion can be up to 25 N / 25 mm, determined at 23 °C.

[0328] Under washing conditions, the peel adhesion can be reduced by 2 - 100 times or 5 - 50 times, for example 1 - 5 cN / 25 mm, or 0 - 5 cN / 25 mm, most preferably less than 2.5 cN / 25 mm, as determined according to this specification.

[0329] Experimental tests

[0330] The washability can be measured by determining the levels of fixation and delamination.

[0331] For example, a 100% fixation level and 0% delamination level means no delamination from the bottle and 100% fixation on the face, i.e., it fails the test.

[0332] Furthermore, a 0% fixation level and 100% delamination level means delamination from the bottle and no fixation on the face.

[0333] Furthermore, for example, a 0% fixation level and an 11% delamination level means a 11% delamination level of the bottle, with no fixation on the face (by the percentage that actually delaminates). Thus, in the case of 11% delamination, 89% of the sheet remains completely unchanged and 11% of the sheet actually delaminates, and the adhesive ends up in the solution.

[0334] Example 1: Washability

[0335] During the experimental tests, the washability of corona-treated film labels was tested.

[0336] The labels were attached to cylindrical PET bottles with a thickness of 0.6 mm. For the washability test, the bottles were broken into 25 g pieces, each with a size of 1 cm x 1 cm.

[0337] According to the test results, when the amount of the washing additive is greater than 5 wt%, the labels can be washed at a temperature of 75°C, and when the amount of the washing additive is 10 wt% or higher, the washability is improved.

[0338] By using a temperature of 65°C, when the amount of the washing additive is at least 10 wt%, the labels can be washed, and when the amount of the washing additive is 15 wt% or higher, the washability is improved.

[0339] When the amount of the washing additive is between 15 and 20 wt%, the best washability results can be obtained.

[0340] Table 1 Test conditions and results

[0341]

[0342] Example 2: Bottle comparison

[0343] The washability tests of different types of bottles are as follows:

[0344] Test Point 1: Cylindrical PET bottle, thickness 0.6 mm.

[0345] Test Point 2: PET bottle, with a square profile and rounded corners, thickness 0.4 mm.

[0346] Test Point 3: Cylindrical PET bottle, thickness 0.5 mm.

[0347] Test Point 4: Milk jug: Polyolefin bottle (HDPE), opaque and flimsy compared to the PET bottle.

[0348] The washability test was repeated for the plastic bottles at Test Points 1 to 4 by using a 24-hour dwell time on the bottles. The washing conditions were 1% NaOH at 65 °C and 75 °C.

[0349] The face material for all test points was BOPP, and the amount of PSA was 15 to 20 gsm.

[0350] All the tested bottles were broken into 25 g pieces (approx. 1 cm x 1 cm) and added to 100 g of the washing solution. Mixing was carried out for 15 minutes.

[0351] Figure 4a Shows the bottle curl of the bottle at 65 °C according to Test Point 1. Figure 4b Shows the bottle curl of the bottle at 65 °C according to Test Point 2. Figure 4c Shows the bottle curl of the bottle at 65 °C according to Test Point 3. Figure 4d Shows the bottle curl of the bottle at 65 °C according to Test Point 4.

[0352] During the experimental tests, it was noted that the type of bottle had an impact on washability. For example, different bottles behaved differently under the washing conditions.

[0353] For all the tested bottles, the label containing the PSA with the wash-off adhesive according to the present application had improved washability compared to the bottles with labels containing a conventional PSA.

[0354] Example 3: Adhesiveness

[0355] The wash-off additive was formulated using a water-based acrylic adhesive, and the adhesiveness was tested using the bottles according to Table 2.

[0356] Table 2 shows the results of adhesiveness. It can be seen that the wash-off additive according to the present application had no clear effect on adhesiveness. In particular, at least for plastic bottles, the wash-off additive did not improve adhesiveness.

[0357] Table 2

[0358] Adhesiveness 0 wt% wash-off additive 20 wt% wash-off additive 5 wt% wash-off additive Glass 6 8 8 PET 11 8 11 HDPE 5 2 6

[0359] Example 4A: Recycling PET Bottles at +65°C

[0360] The adhesives according to the present application (which include grafted rosin esters containing PEG) were blended with different water-based acrylic adhesives and tested in the tests under alkaline conditions with 1% NaOH at +65°C.

[0361] The test points included the following addition dosages: 0 to 20% by weight (dry weight), determined by the total dry weight of the acrylic adhesive. For these tests, mechanically oriented and biaxially oriented polypropylene films were used as the face films.

[0362] Some test points included 0.2 to 0.5% by weight (dry weight) of a non-ionic biodegradable surfactant. It was noted that when used together with the wash-off additive, adding the surfactant further improved the washability at +65°C.

[0363] According to the test results, compared with the test point of 0% by weight, adding more than 5% by weight (dry weight) of the wash-off additive to the acrylic adhesive improved the washability of the label. When adding 10% by weight, the improvement in washability was more significant.

[0364] Therefore, adding more than 5% by weight, especially 10 to 20% by weight (dry weight) of the wash-off additive clearly improved the washability at +65°C. When the wash-off additive was added at 15% to 20%, the best washability results were shown.

[0365] Example 4B: Recycling PET Bottles at +65°C, Comparative Example

[0366] Mechanically oriented and biaxially oriented polypropylene films were used as the face films for these tests.

[0367] A conventional rosin ester dispersion without the wash-off additive was blended with different water-based acrylic adhesives and tested in the tests at +65°C using the same conditions as in Example 4A.

[0368] In addition, a conventional PEG solution was blended with different water-based acrylic adhesives and tested in the tests at +65°C using the same concentration range as in Example 4A.

[0369] At +65°C, adding the conventional rosin ester dispersion did not improve the washability. On the contrary, the conventional rosin ester dispersion even reduced the washability.

[0370] In addition, at +65 °C, the addition of the PEG solution did not improve the washability, and the adhesive had poor washability or could not be washed at all.

[0371] Example 5A: Recycling of HDPE bottles at +40 °C

[0372] The wash-off adhesive according to the present application (which contains a grafted rosin ester containing PEG) was blended with different water-based acrylic adhesives and tested in a wash-off test in plain water at +40 °C.

[0373] The test points included paper labels. The amount of the wash-off additive was 0 to 20 wt% (dry weight), determined by the total dry weight of the acrylic adhesive.

[0374] The addition of at least 5 wt% (dry weight) of the wash-off additive clearly improved the washability in water at +40 °C. At the addition of 10 wt%, the improvement in washability was even more significant. For all test points, complete delamination took only about 5 minutes, and within 10 minutes, the paper had completely disintegrated.

[0375] Example 5B: Recycling of HDPE bottles at +40 °C, comparative example

[0376] A conventional rosin ester dispersion without a wash-off additive was blended with different water-based acrylic adhesives and tested in a wash-off test at +40 °C using the same conditions as in Example 5A.

[0377] In addition, a conventional PEG solution was blended with different water-based acrylic adhesives and tested in a wash-off test at +40 °C.

[0378] At +40 °C, the addition of the conventional rosin ester dispersion did not improve the washability. On the contrary, the conventional rosin ester dispersion decreased the washability.

[0379] In addition, at +40 °C, the addition of the PEG solution did not improve the washability, and the adhesive had poor washability or could not be washed at all.

[0380] Example 6: Hydrophobicity

[0381] The wash-off additive was formulated using different water-based acrylic adhesives and the hydrophobicity was tested.

[0382] According to the test results, the wash-off additive clearly increased the hydrophobicity, further improved the washability of the acrylic adhesive containing the adhesive, and improved the delamination of the label from PET and polyolefin bottles.

[0383] During the experimental tests, compared with the conventional solutions, the novel additive has several advantages. Conventional rosin ester dispersions cannot act as wash-off additives. In addition, PEG solutions do not improve the washing performance of acrylic adhesives at all. Unexpectedly, according to the present application, the wash-off additive containing grafted rosin esters can effectively improve the properties of acrylic polymers during low-temperature washing processes at 40 °C and 65 - 75 °C, and can improve delamination during the washing process.

[0384] The present invention has been described with reference to the drawings and examples. The present invention is not limited to the above-described embodiments, but can be modified within the scope of the appended claims.

Claims

1. A method of making a label comprising a face and a pressure-sensitive adhesive layer for adhering the label to a surface of an object to be labeled, The method comprises: - applying an acrylic adhesive to the first surface of the face, wherein the acrylic adhesive comprises a rinse-off additive comprising: ○ Water phase, o a resinous material, preferably selected from the group consisting of hydrocarbon resins, alkyd resins, polyamide resins, rosin resins, and mixtures thereof, and o a grafted rosin ester, which is preferably a rosin ester grafted with a capped polyalkylene glycol, wherein the capped polyalkylene glycol is preferably a polyalkylene glycol capped by an alkyl ether end, wherein the amount of the rinse-off additive is at least 4 wt.%, preferably 5 to 25 wt.%, calculated on the total dry weight of the acrylic adhesive, and - drying the acrylic adhesive so as to form an acrylic pressure-sensitive adhesive onto the first surface of the face portion, The label is thus obtained.

2. The method according to claim 1, wherein the polymer gel content of the acrylic adhesive is at least 10%, preferably at least 50%, more preferably at least 60%, and at most 75%.

3. The method according to claim 1 or 2, wherein the average particle size of the acrylic adhesive is at least 100 nm and at most 800 nm, measured as the average particle diameter.

4. A label comprising a face portion and a pressure-sensitive adhesive layer for adhering the label to the surface of an object to be labeled, The pressure-sensitive adhesive layer comprises: - an acrylic pressure-sensitive adhesive comprising a wash-off additive, the wash-off additive comprising: o a resinous material, preferably selected from the group consisting of hydrocarbon resins, alkyd resins, polyamide resins, rosin resins, and mixtures thereof, and ○ Grafted rosin ester, which is preferably a rosin ester grafted with a capped polyalkylene glycol, wherein the capped polyalkylene glycol is preferably an alkyl ether-terminated polyalkylene glycol, The amount of the rinse-off additive is at least 4 wt%, preferably 5 to 25 wt%, calculated based on the total dry weight of the acrylic adhesive.

5. A method or label according to any preceding claim wherein the amount of the wash-off additive is from 10 to 20 wt%, calculated on the total dry weight of the acrylic adhesive.

6. A method or label according to any preceding claim wherein the amount of grafted rosin ester relative to the resinous material is from 1% to 8% by weight.

7. A method or label according to any preceding claim, wherein the polyalkylene glycol is polyethylene glycol.

8. A method or label according to any preceding claim wherein the acrylic adhesive comprises 2-ethylhexyl acrylate.

9. A method or label according to any preceding claim, wherein the resinous material comprises or consists of the rosin resin.

10. A method or label according to any preceding claim wherein the molar ratio between the rosin ester and the capped polyalkylene glycol is from 0.05:1 to 1:

1.

11. A method or label according to any preceding claim, wherein the alkyl ether is a methyl ether.

12. A method or label according to any preceding claim, wherein the label is a linerless label.

13. A method or label according to any preceding claim 1 to 11 wherein the label is a label laminate comprising a release liner.

14. A method or label according to any preceding claim, wherein the face portion comprises a thermoplastic film, preferably an oriented thermoplastic film, more preferably a biaxially oriented thermoplastic film.

15. A method or tag according to any preceding claim, wherein the face is configured to contract asymmetrically.

16. A method or label according to any preceding claim wherein the face comprises a uniaxially oriented thermoplastic film which is uniaxially oriented in the machine direction of the film.

17. A method or label according to any preceding claim wherein the face comprises a polypropylene film or a glycol-modified polyethylene terephthalate film.

18. A method or label according to any preceding claim 1 to 13 wherein the face comprises paper.

19. A method or label according to any preceding claim, wherein the label is a direct thermal label.

20. A method or label according to any preceding claim, wherein the label is a wash-off label.

21. A beverage bottle comprising a label according to any one of the preceding claims 4 to 19, the label being adhered to a surface of the beverage bottle, Preferably, the density of the label and the beverage bottle is as follows: the density of one is greater than that of water, and the density of the other is less than that of water.

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