Patent Application
20130133532
The present invention generally relates to systems and machines for activatable adhesive labels, and to labels and adhesives for linerless and heat activatable uses. More specifically, the invention relates to systems and methods for activatable adhesives and activation adhesives of linerless labels using radiation and temperature changes and to linerless labels and adhesives useful in activatable technologies.
Traditional pressure sensitive labels are supplied to the user affixed to a release liner. These release liners are typically silicone coated, and, as such, are not usable as sources for recycled paper. In an effort to reduce cost, improve efficiencies, and reduce environmental impact, consumer demand for labels without liners has increased in recent years. The most common forms of these labels are “linerless labels” and “activatable labels”.
“Linerless labels” have a sticky side and a release-coated side so they can be wound upon themselves into rolls. The use of these linerless labels requires either preprinting or special printers that are configured to print on release coating. The equipment used to manipulate linerless labels includes special rollers and platens that are configured to contact the sticky side of the labels. Despite many improvements in this equipment, adhesive buildup still occurs in various sections of the equipment. Because of these shortcomings, and also the high price of the final sticky “linerless” product, these linerless labels have not received wide customer acceptance.
“Activatable labels” are supplied to the end user in a non-tacky state, and then the labels are activated, i.e., the label's adhesive is activated, to a tacky state just prior to application to the intended object. Most often, activatable labels are printed with indicia prior to activation. Known activation schemes include the use of ultraviolet (“UV”) energy to heat the adhesive (see U.S. Pat. No. 6,492,019 to Shipston et al.), corona treatment to activate the surface (see U.S. Pat. No. 6,326,450 to Shipston et al.), radiant heat to warm the adhesive (see U.S. Pat. No. 6,500,536 to Yamada et al.), moisture to activate a rewettable adhesive (see U.S. Pat. No. 6,803,100 to Hintz et al.), microencapsulating an activator material, which can then be crushed to allow the activator to mix with the rest of the formulation and activate the adhesive (see U.S. Pat. No. 7,026,047 to Krolzig), overcoating the adhesive with a detackifier layer, which is later removed by heat or mechanical means (see U.S. Pat. No. 5,569,515 to Rice et al.), and ultrasound energy to activate the adhesive (see U.S. Pat. No. 5,702,771 to Shipston et al.).
By far, the most common activation scheme utilizes heat activation, i.e., the activation of the label using heat. For heat activation, various techniques have been proposed. These include the use of the following: heated drums or rollers (see U.S. Pat. Nos. 5,749,990 and 5,480,502 to Rello et al.), direct contact with the heating element (see U.S. Pat. Nos. 6,388,692 to Iwata et al. and 6,501,495 to Ichikawa et al.), microwave energy (see U.S. Pat. No. 3,461,014 to James), heated belts in contact with the adhesive (see U.S. Pat. Nos. 4,468,274 to Adachi and 6,031,553 to Nagamoto et al.), and infrared (“IR”) and near infrared radiation (“NIR”) (see U.S. Pat. Nos. 3,247,041 to Henderson and 4,156,626 to Souder). In addition, general methods for heating using radio frequency (“RF”) energy, inductive heat, radiant heat, and visible light also are well known and could be applied to this list of activation methods. These techniques have all proven useful at low-speed operations, but as application speeds increase, these methods all suffer in that the exposure times of the labels to the heating elements must somehow be increased in order to gain sufficient heating. Either the size or the cost of the units capable of supplying sufficient heating has thwarted high-speed applications.
One way to overcome the need for larger or longer heaters is to increase the ability of the adhesive to absorb the energy from the heating devices. U.S. Pat. Nos. 4,156,626 to Souder and 6,043,190 to Ichikawa et al., and U.S. Patent Application Publication Numbers 2003/0041963 and 2004/0166309 to Gong et al all describe the use of NIR absorbers to increase the energy absorbance by adhesives. Hence, the use of NIR absorbers and high-intensity NIR lamps might appear to be a viable route for activating the adhesive. Although satisfactory in many respects, disadvantages exist involving currently known activatable labels, labeling systems, and related methods.
Various details and disclosure concerning this type of technology is found in U.S. application Ser. No. 13/119,006, a National Stage entry of PCT/US10/47428, published as WO 2011/037732, published Mar. 31, 2011, to Kian et al.
Both rubber-based and acrylic-based pressure sensitive adhesives (PSAs) are known. In 1966, C. Dalquist identified al second creep compliance greater than 1×10−6 cm2/dyne as the efficient contact criterium of a good PSA. A more recent discussion of PSAs in the Handbook of Pressure Sensitive Adhesive Technology (2d Edition), D. Satas, ed. (1989), (hereafter, “Handbook”), pages 172-176, incorporated by reference herein, identifies glass transition temperature (Tg) and modulus (G′) at the application (use) temperature as the most important requirements for PSA performance. Both properties are a function of the identities and amounts of monomers that comprise the PSA polymer(s). Thus, poly(acrylic acid) is not a PSA, but a copolymer of acrylic acid with high mole % of 2-ethylhexyl acrylate is.
The typical values of G′ and Tg for label and tape PSAs are described in the Handbook. For a tape, G′ at room temperature is approximately 5×105 to 2×106 dyne/cm2, and Tg is approximately −15° C. to 10° C.; while labels have a lower value of G′ at room temperature, i.e., about 2×105 to 8×105 dyne/cm2. Tg requirements for cold temperature, permanent, and removable applications are different, as is known in the art. Thus, cold temperature label PSAs generally require a Tg of from about −30° C. to −10° C.
All patents, published applications, and articles noted herein are hereby incorporated by reference in their entirety.
The embodiments of the present disclosure described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of the present disclosure.
An exemplary embodiment of the present disclosure is an aqueous adhesive composition which is activatable by exposure to infrared (“IR”) radiation and which exhibits pressure sensitive adhesive properties once activated by IR or by heating. The adhesive composition comprises (i) an emulsion base copolymer exhibiting a glass transition temperature Tg above 25° C. and a weight average molecular weight within a range of from 15,000 Daltons to 100,000 Daltons, (ii) a solid plasticizer for such copolymer exhibiting a melting point above 40° C., and (iii) a high softening point tackifier.
Another exemplary embodiment is an adhesive that includes a plasticizer, a tackifier, and an adhesive base polymer that includes a lower alkyl acrylate such as butyl acrylate, styrene, methyl methacrylate, methacrylic acid, and acrylic acid.
Generally, the present adhesive system comprises from about 20% to about 35% of an adhesive base polymer, from about 50% to about 75% of a plasticizer, and from about 5% to about 20% of a tackifier. Preferably, this type of adhesive system comprises from about 24% to about 30% of an adhesive base polymer, from about 56% to about 68% of a plasticizer, and from about 8% to about 16% of a tackifier.
In a more detailed embodiment, particular formulations are provided for the adhesive systems. In one preferred composition, the adhesive comprises about 25% of an adhesive base polymer, about 66% of a plasticizer, and about 9% of a tackifier. In another preferred composition, the adhesive comprises about 255% of an adhesive base polymer, about 66% of a plasticizer, and about 8.5% of a tackifier.
In a more detailed embodiment, particular linerless label adhesive formulations are provided that incorporate an adhesive base polymer, a tackifier, and a plasticizer that contains substantial quantities of plant-based molecule to enhance the bio-based content of the adhesive formulation and of the linerless labels. In a preferred system, the plant-based molecule comprises at least 20%, typically over 20% of the plasticizer.
Generally, in one embodiment, an adhesive base polymer for the labels, machine, system and method includes from about 10% to about 50% of at least one lower alkyl acrylate, from about 20% to about 85% styrene, from about 1% to about 35% methyl methacrylate, from about 0.5% to about 5% methacrylic acid, from about 0.5% to about 5% acrylic acid, from about 0% to about 5.0% of at least one multifunctional monomer, and from about 0% to about 5.0% of at least one chain transfer agent. In a more detailed aspect, the adhesive base polymer comprises from about 12% to about 48% of at least one lower alkyl acrylate, from about 23% to about 78% styrene, from about 3% to about 30% methyl methacrylate, from about 1% to about 2% methacrylic acid, from about 1% to about 3% acrylic acid, from about 0.5% to about 2.5% of at least one multifunctional monomer, and from about 1.0% to about 4.0% of at least one chain transfer agent.
In another detailed embodiment, particular formulations are of a type incorporating adhesive base polymers where the butyl acrylate is about 37.2% of an adhesive base polymer, the styrene is about 29.3% of the adhesive base polymer, the methyl methacrylate is about 29.3% of the adhesive base polymer, the methacrylic acid is about 1.7% of the adhesive base polymer, and the acrylic acid is about 2.5% of the adhesive base polymer. In another embodiment, the butyl acrylate is about 48.0% of the adhesive base component, the styrene is about 23.9% of the adhesive base component, the methyl methacrylate is about 23.9% of the adhesive base component, the methacrylic acid is about 1.7% of the adhesive base component, and the acrylic acid is about 2.5% of the adhesive base component. In still another embodiment, the butyl acrylate is about 12.8% of the adhesive base component, the styrene is about 77.6% of the adhesive base component, the methyl methacrylate is about 3.2% of the adhesive base component, the methacrylic acid is about 1.2% of the adhesive base component, and the acrylic acid is about 1.7% of the adhesive base component, a multifunctional monomer amount is 1.5%, and a chain transfer agent amount is 1.9%.
In other more detailed features, an adhesive is white. Also, in other features, the adhesive does not include and so, is free from carbon black, graphite, an ink, a dye, a pigment, and/or a colorant.
In addition, a plasticizer can be UNIPLEX 260 or glyceryl tribenzoate having about 22% bio-based content, and a tackifier can be Tamanol E-102A and Super Ester E-730 or Super Ester E-650. The plasticizer can be UNIPLEX 250 or dicyclohexyl phthalate, and the tackifier can be ARAKAWA SE-E 650.
In other more detailed features, a plasticizer is configured to melt upon and/or after exposure to energy. Also, an adhesive can be configured to be activated by exposure to energy for less than one second. In addition, the adhesive can be configured to be activated by exposure to energy for less than 0.5 second or for less than 0.3 second.
In other more detailed features, the energy is near infrared radiation (“NIR”), short IR energy, Mid Wave IR energy, IR energy, microwave energy, RF energy, inductive heat energy, visible light energy, radiant heat energy, or UV energy. Also, the IR energy can have a peak wavelength from approximately 0.8 μm to approximately 3.0 μm. In addition, the IR energy can have a second peak wavelength from approximately 1.2 μm to approximately 2.5 μm.
In other more detailed features, a system and machine cooperate with the adhesive formulation and label to activate the adhesive so same has a tackiness, and the adhesive's tackiness is maintained for at least approximately two minutes after the adhesive is activated.
Another exemplary embodiment, the system, machine and method apply a label that includes a facestock layer and an adhesive layer that is coupled to the facestock layer. The adhesive layer includes a plasticizer, a tackifier, and an adhesive base polymer that includes butyl acrylate, styrene, methyl methacrylate, methacrylic acid, and acrylic acid.
in other more detailed features, a label is configured to be exposed to radiant energy, the radiant energy has a wavelength and an intensity that results in the adhesive layer becoming tacky after exposure to the radiant energy, and a facestock layer is not discolored after the exposure of the label to the radiant energy. Also, the facestock layer can be made of paper, recycled paper, polymer film, metalized paper, metalized film, paper backed foil, or metal foil.
In other more detailed features, the system, machine and method apply a label configured to be applied to the item, and to be repositioned for approximately one minute after the label is applied to the item. Also, an adhesive layer can be activatable, have a tackiness, and be configured to be applied to the item, so that after the label is applied to the item, the adhesive layer's tackiness prevents the label from inadvertently being removed from the item. In addition, the label can be configured to be applied to the item, and after the label is applied to the item, the label permanently bonds with the item after approximately two hours.
In another exemplary embodiment, the system, machine and method apply a label assembly comprising a facestock layer and a heat activatable adhesive layer, and a functional coating layer disposed between the adhesive layer and the facestock layer.
Another exemplary embodiment is a label that includes a facestock layer, an adhesive layer, and a reflective layer that is coupled between the facestock layer and the adhesive layer.
Another exemplary embodiment applies a label that includes a facestock layer, an adhesive layer, and a barrier layer disposed between the facestock layer and the adhesive layer. Another exemplary embodiment applies a label that includes a facestock layer, an adhesive layer, and a primer layer disposed between the facestock layer and the adhesive layer. When included, the barrier and/or primer layer can be added to provide thermally insulating properties to facilitate direct thermal printing of linerless laminates.
In other more detailed features, an adhesive layer of the various linerless label assemblies includes a plasticizer, a tackifier, and an adhesive base polymer including butyl acrylate, styrene, methyl methacrylate, methacrylic acid and acrylic acid.
In other more detailed features, a system, machine and method apply a label so as to be configured to be exposed to a radiant energy, the radiant energy has a wavelength and an intensity that results in an adhesive layer becoming tacky after exposure to the radiant energy, and a facestock layer is not discolored after the exposure of a label to the radiant energy. Also, the facestock layer can have a bottom surface, and the label can include a reflective layer that is made of a material that is applied as a coating to the bottom surface of the facestock layer. In addition, the material of the reflective layer can be gold, silver, aluminum, or copper. Furthermore, the reflective layer can have a thickness of not greater than one micron.
In other more detailed features of labels applied by a system, machine or method have a reflective layer with a reflectivity value, and the reflectivity value is greater than approximately 90 percent. Also, the reflective layer can underlie only a portion of the facestock layer. In addition, an adhesive layer can have a first surface, the reflective layer can have a second surface that is adjacent to the first surface, and the second surface can be textured. Furthermore, the second surface's texture can be configured to be retroreflective.
In other more detailed features, a system, machine and method are arranged so a label is configured to be exposed to a radiant energy, the radiant energy has a wavelength and an intensity that results in the adhesive layer becoming tacky after exposure to the radiant energy, and the facestock layer is not discolored after the exposure of the label to the radiant energy. Also, the facestock layer can have a bottom surface, and the label can include a barrier layer that is made of a material that is applied as a coating to the bottom surface of the facestock layer. In addition, the material of the barrier layer is selected so as to prevent or at least significantly reduce discoloration of the facestock layer.
Another exemplary embodiment is a system that is configured to facilitate the application of an activatable label to an item. The system includes an energy source that is configured to emit energy and one or more actuators that are configured to receive the activatable label, transport the activatable label through the emitted energy, and transport the activatable label to a position where the activatable label is applied to the item. The activatable label includes an adhesive having a plasticizer, a tackifier, and an adhesive base polymer that includes butyl acrylate, styrene, methyl methacrylate, methacrylic acid, and acrylic acid.
Another exemplary embodiment is a system that is configured to facilitate the application of a flow of activatable labels to a flow of items. The system includes an energy source that is configured to emit energy, a printer that is configured to print indicia on the activatable label, and one or more actuators that are configured to receive the activatable labels, transport the activatable label past the printer that then prints the indicia on the activatable labels, transport the activatable labels through the emitted energy, and transport the activatable labels to a position where the activatable labels are applied to the items. The activatable labels include an adhesive having a plasticizer, a tackifier, and an adhesive base polymer that includes butyl acrylate, styrene, methyl methacrylate, methacrylic acid, and acrylic acid.
In other more detailed features of a system, machine and method, one or more actuators include a blower system, a conveyor belt, a paddle, a carrier sheet, a plunger, a vacuum drum, a roller, a vacuum belt, or a vacuum head. Also, an item to receive activatable labels can be a moving line of bottles, cans, containers, vessels, bags, pouches, envelopes, parcels, or boxes. In addition, the activatable label can be one of a stack of precut activatable labels.
An exemplary method applies a label with an activatable adhesive to an item as same move for processing. The method includes providing the label that has a first surface that is coated with the activatable adhesive, the adhesive including a plasticizer, a tackifier, and an adhesive base polymer including butyl acrylate, styrene, methyl methacrylate, methacrylic acid, and acrylic acid. The method also includes providing the item that has a second surface, providing a source of energy that is configured to output radiant energy, exposing the first surface of the label to the radiant energy that is output from the source of energy so the first surface of the label becomes tacky, and placing the first surface of the label in contact with the second surface of the item.
In other more detailed features, a label is pre-printed with indicia. Also, a method can further include providing a printer that is configured to print an image on the label, and printing the image on the label before the step of exposing the label to the radiant energy. Also the method includes providing a cutter that is configured to cut the dry label to a desired length before the activation stage. In addition, the label can include a facestock layer and an adhesive layer. The adhesive layer includes the adhesive base polymer, the plasticizer, and the tackifier, and the facestock layer is not discolored after the exposure of the label to the radiant energy.
In other more detailed features, providing a label includes providing a plurality of labels, providing an item includes providing a plurality of items, exposing the label includes exposing at least one of the plurality of the labels to the radiant energy, and placing the label in contact with the item includes placing one of the plurality of labels in contact with one of the plurality of items at a rate greater than 10 label per minute. Also, a step of placing the label in contact with the item depends on the item to label, it includes placing one of the plurality of labels in contact with one of the plurality of items at up to 100 labels per minute for some items and a rate of less than or equal to approximately 1,000 labels per minute in some applications.
Another exemplary method activates a label. The method includes providing the label having a first surface that is coated with an activatable adhesive, the activatable adhesive includes a plasticizer, a tackifier, and an adhesive base polymer including butyl acrylate, styrene, methyl methacrylate, methacrylic acid, and acrylic acid. The method also includes providing a source of energy that is configured to output radiant energy, and exposing the label to the radiant energy that is output from the source of energy so the first surface of the label becomes tacky.
In another exemplary embodiment, a system is provided for printing and applying linerless labels to articles. The system comprises a printer unit, a thermal activation unit downstream of the printer unit, and an applicator unit downstream of the thermal activation unit. The thermal activation unit includes a label transport assembly and one or more emitters that are configured to emit radiation to labels. In particularly preferred aspects of this system, unique sensor arrangements are utilized to assess whether label degradation condition(s) are occurring. And, optional quartz glass members are preferably used to improve safety and operability of the system.
Other features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description. It is to be understood, however, that the detailed description of the various embodiments and specific examples, while indicating preferred and other embodiments of the present invention, are given by way of illustration and not limitation. Many changes and modifications within the scope of the present invention may be made without departing from the spirit thereof, and the invention includes all such modifications.
These, as well as other features, aspects, and advantages of this invention, will be more completely understood and appreciated by referring to the following more detailed description of the exemplary embodiments of the invention in conjunction with the accompanying drawings.
Unless otherwise indicated, the illustrations in the above figures are not necessarily drawn to scale.
The apparatuses and methods disclosed in this document are described in detail by way of examples and with reference to the figures. Unless otherwise specified, like numbers in the figures indicate references to the same, similar, or corresponding elements throughout the figures. It will be appreciated that modifications to disclosed and described examples, arrangements, configurations, components, elements, apparatuses, methods, materials, etc. can be made and may be desired for a specific application. In this disclosure, any identification of specific shapes, materials, techniques, arrangements, etc. are either related to a specific example presented or are merely a general description of such a shape, material, technique, arrangement, etc. Identifications of specific details or examples are not intended to be, and should not be, construed as mandatory or limiting unless specifically designated as such. Selected examples of apparatuses and methods are hereinafter disclosed and described in detail with reference made to the figures.
Use of energy absorbers in an adhesive formulation is well documented, but in certain instances, can result in darkly colored adhesives that are not compatible with the aesthetic requirements of today's consumer market. Activatable linerless label adhesives achieve maximum, or substantially maximum, energy transfer when in use by matching an absorbance range of an adhesive with an emission range of a radiation or energy source. The radiation source can emit a broad spectrum of energy wavelengths, typically with a peak wavelength, i.e. the wavelength associated with a peak energy value in the spectrum. The activatable linerless label adhesives demonstrate high absorption properties that allow for the activatable linerless label adhesives to be heat activated at faster rates while requiring less energy to power the radiation sources and without a drawback of having the darkly colored adhesive. Likewise, by tuning an adhesive absorption to approximately match a radiation emission, a majority of energy that is radiated upon an activatable linerless label is absorbed by an adhesive, leaving little energy remaining to couple with a facestock or an indicia printed upon the facestock. If energy is allowed to be absorbed by the facestock or the indicia, a resulting heating of the facestock or the indicia can cause discoloration of the facestock. While tuning the adhesive's absorption to the radiation source lowers the occurrence of this form of facestock discoloration, in some cases additional measures to avoid discoloration of the facestock are warranted. These include use of a functional layer such as a reflective layer and/or a barrier layer between the adhesive and the facestock. The functional layer could be in the form of a primer layer.
It will be appreciated that it is possible to provide activatable linerless label adhesives that are opaque or dark in appearance. Activatable linerless label adhesives that need to be transparent, translucent or white in appearance can be formulated to be substantially free of additives, pigments, dyes, inks, and/or colorants such as for example, carbon black or graphite. In other situations, the activatable linerless label adhesives may contain one or more additives, pigments, dyes, inks, and/or colorants such as for example carbon black or graphite.
An important attribute of the activatable adhesive is its ability to stay in an activated state, i.e., the adhesive is in a tacky state, long enough to allow application of the activatable linerless label to an item, such as a container or an article, before the adhesive loses its tackiness. This time period is commonly referred to as an “open time” of the adhesive. Depending on an application speed of the activatable linerless label to the item, and a distance between a activating device and a point where the activatable linerless label is applied to the item, this open time could be a fraction of a second and as long as several minutes or more. Embodiments of the adhesive can be repositionable for approximately 60 seconds, e.g., one minute, after application of the activatable linerless label to the item so that minor adjustments can be made to the activatable linerless label's position on the item immediately after application. Embodiments of the adhesive form a permanent bond between the activatable linerless label and the item within approximately two minutes, after activation of the activatable linerless label, so that the activatable linerless label cannot inadvertently be removed from, or repositioned on, the item.
Various activatable linerless label adhesives or adhesive systems are provided as described in greater detail herein. However, it will be appreciated that in no way is the invention limited to the use of particular adhesive systems described herein. Preferably, the adhesive systems utilize the particular adhesive base polymers described herein. The adhesive systems generally comprise (i) an adhesive base polymer, (ii) a plasticizer, and (iii) a tackifier. Typical and preferred weight percent concentrations for each of these components are set forth below in Table 1. It will be appreciated that the noted weight percent concentrations are based upon the total weight of components (i)-(iii). Thus, it is contemplated and expected that the adhesive systems may include additional components and additives in addition to components (i)-(iii) listed below in Table 1.
The preferred adhesive systems described herein generally comprise the adhesive base polymer (described in greater detail herein), the plasticizer which preferably, is in a solid crystalline state below an application temperature, and the solid tackifier which preferably is also in a solid state below the application temperature. Physical states of an adhesive material can be switched between solid and non-solid by altering the temperature. The open time of an adhesive can be controlled by adjusting a ratio of the components, i.e. the adhesive polymer base, the plasticizer, and the tackifier. The preferred activation temperature is preferably within the range of from about 50° C. to about 120° C. However, it will be understood that the invention is not limited to adhesive systems exhibiting activation temperatures within this range.
At a switching temperature of the activatable linerless label adhesive, the properties of adhesion and viscosity markedly change. Therefore, a pressure sensitive adhesive system can be thermally switched from “off” to “on” by using these strategies described herein. If such adhesive system is then coated on the facestock at a temperature below the designed switch temperature, the adhesive material is in its non-sticky solid state. Thus, a label construction can be wound in a roll form. During the application process, the temperature is increased to the switching temperature so that the adhesive material will change to a non-solid state and then exhibit its pressure sensitive adhesive properties, which allow the activatable linerless label to be adhered to a substrate as desired as a result of increased adhesion properties. If the substrate exhibits a porous surface, the preferred embodiment adhesive systems will flow into the pores and “stick” very well, as a result of the interlocking effect even when the temperature is reduced below that of the switching temperature of the adhesive material.
The formulation shown in Table 2, illustrates one exemplary adhesive formulation wherein glyceryl tribenzoate is used both as the plasticizer and as higher percentage source of bio-based content, as well as an energy absorption agent. In this plasticizer, a glycerol component is a plant-based molecule that makes up about 22% of the glyceryl tribenzoate. Other examples of plasticizers for these types of formulations include dicyclohexyl phthalate, diphenyl phthalate and 1,4-cyclohexane dimethanol dibenzoate.
66%
As explained in greater detail herein, in forming the adhesive polymer base, it is preferred to utilize effective amounts of one or more multifunctional monomers and one or more chain transfer agents. A representative preferred multifunctional monomer is ethylene glycol dimethacrylate. A preferred chain transfer agent is n-dodecyl mercaptan.
The present invention also provides various preferred embodiment adhesive polymer bases comprising (i) one or more lower alkyl acrylates, (ii) styrene, (iii) methyl methacrylate, (iv) methacrylic acid, (v) acrylic acid, one or more multifunctional monomers, and one or more chain transfer agents. In one embodiment, typical and preferred concentrations for each of these components are set forth below in Table 3 as follows. The weight percent concentrations listed in Table 3 are based upon the total weight of the adhesive polymer base. It will be understood that the various adhesive base polymers described herein are merely representative in nature. Although generally constituting preferred embodiments of the invention, in no way is the invention limited to the use of the particular adhesive polymer bases described herein.
A wide array of lower alkyl acrylates can be used singly or in combination for component (i) in the preferred embodiment adhesive polymer base. For example, methyl acrylate, butyl acrylate, ethyl acrylate, and 2-ethylhexyl acrylate could be used. However, butylate acrylate and ethyl acrylate are generally preferred with butyl acrylate being most preferred. A wide array of styrene and styrene based materials can be used for component (ii). Similarly, for component (iii), it is generally preferred that methyl methacrylate be used. However, it will be appreciated that other analogues and functionally equivalent monomers could be used in conjunction with or instead of methyl methacrylate.
The preferred monomer for component (iv) is methacrylic acid. However, it will be appreciated that the invention includes other equivalent monomers in conjunction with or instead of methacrylic acid. Although acrylic acid is noted for use as component (v), it will be understood that the invention includes use other equivalent monomers.
A wide array of multifunctional monomers or multifunctional monomer agents can be used in the present invention. The multifunctional monomers can be used to achieve cross-linking of the adhesive base polymer. Representative examples of such multifunctional monomers include, but are not limited to, difunctional monomers, trifunctional monomers, and multifunctional monomers having more than three active functional sites. Preferred examples of difunctional monomers include, but are not limited to 1,4-butanediol diacrylate, polyethylene glycol diacrylate, and combinations thereof. Another preferred difunctional monomer is ethylene glycol dimethacrylate. Preferred examples of trifunctional monomers include, but are not limited to ethoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, and combinations thereof. Preferred examples of multifunctional monomers having more than three active functional sites include, but are not limited to, ethoxylated pentaerythritol tetraacrylate, and combinations thereof. These and numerous other suitable multifunctional monomers are commercially available from various suppliers such as Sartome Company, Inc. of Exton, Pa. Typical concentrations of multifunctional monomers range from about 0 to about 5.0%, with from about 0.5% to about 2.5% being preferred, and from about 1.5% to about 2.0% being most preferred.
Chain transfer agents, when used in forming the activatable linerless label adhesives, are typically used at concentrations of from about 0 to about 5.0%, and preferably from about 1.0% to about 4.0% (percentages are based upon the total weight of monomer and chain transfer agent). Representative examples of suitable chain transfer agents include, but are not limited to n-dodecyl mercaptan, tert-nonyl mercaptan, isooctyl 3-mercaptopropionate, and combinations thereof. It will be understood that in no way is the invention limited to these chain transfer agents. Instead, a wide array of chain transfer agents can be used. Suitable chain transfer agents are available commercially such as from Sigma Aldrich of St. Louis, Mo. Most preferably, the adhesive polymer bases include both (i) one or more multifunctional monomer agents and (ii) one or more chain transfer agents.
In one embodiment, a particularly preferred adhesive polymer base composition is set forth below in Table 3A.
The activatable linerless label adhesives have unique characteristics that enable them to be used in numerous applications. One feature of the activatable linerless label adhesives relates to a relatively short time period required for activating the activatable linerless label adhesive, i.e. selectively changing the activatable linerless label adhesive from a non-tacky state to a tacky state. Fast activation times enable the adhesive to be used in high speed labeling operations. Preferably, the activatable linerless label adhesives of the present invention can be activated within a time period of about 0.3 seconds and generally activated in a time period of less than 1 second, and more typically, less than 0.5 seconds. This time period is referred to herein as the adhesive's “activation time.”
As previously described herein, the activatable linerless label adhesives, once activated, remain in their activated state long enough to at least allow application of a label carrying the activatable linerless label adhesive to the item or receiving substrate before the activatable linerless label adhesive loses its tackiness. For example, the activatable linerless label adhesives preferably exhibit an open time of at least from about 0.1 second to 10 minutes or longer. For certain applications, the activatable linerless label adhesives can be tailored to exhibit relatively long open times, such as up to 72 hours or longer. Typically, the activatable linerless label adhesives of the invention exhibit open times of from 10 seconds to 60 seconds.
Once the activatable linerless label adhesives are activated, i.e. while in their “open” and tacky state, the activatable linerless label adhesives exhibit relatively high tackiness. For example, the activatable linerless label adhesives exhibit an initial peak tack to the substrate such as cardboard or steel of at least about 1.0 Newton, and preferably at least about 1.25 Newtons. As described in conjunction with the examples presented herein, typically, the preferred embodiment of linerless label adhesives exhibit initial peak tack values in the range of from 1.0 Newton to 2.0 Newtons. These tack values are measured using SPAT, which is described in detail herein. Preferably, these tack values are with regard to the substrates as described herein. However, it will be appreciated that the present invention is not limited to linerless label adhesives that exhibit these tack values in association with the substrates described herein. That is, it is contemplated that the activatable linerless label adhesives exhibit these tack values in association with other substrates and substrate materials not expressly described herein. Furthermore, it is generally preferred that upon activation of the activatable linerless label adhesive, the tackifier softens and is in a flowable state.
In addition, in certain embodiments, the activatable linerless label adhesives are generally clear after activation to allow the passage of light without any detrimental absorbance. Preferably the activatable linerless label adhesives, once activated, remain in a clear or at least substantially clear state for relatively long time periods and preferably for at least 1 year, and more preferably longer than 1 year. It will also be understood that in other embodiments of the invention, the activatable linerless label adhesives may contain one or more pigments, dyes, inks, colorants or the like such as for example, carbon black or graphite. In the event that the activatable linerless label adhesive contains carbon black or graphite, typical concentrations range from about 0.01% to about 0.1% and preferably from about 0.02% to about 0.08%, based on wet weight. In certain applications, a concentration of about 0.05% of carbon block is used. A wide array of commercially available sources of carbon black may be used. Preferably, carbon black from Cabot Corporation of Boston, Mass. is utilized. Another preferred carbon black is available under the designation AURASPERSE W-7012, available from BASF Corporation of Florham Park, N.J.
The activatable linerless label adhesives can be water based or other form, in which the adhesive base polymer is blended with other adhesive components such as the solid plasticizer, and/or the solid tackifier to yield a linerless label adhesive that is heat activatable, and particularly, a light activatable adhesive such as near infrared radiation (“NIR”) to Mid infrared (“IR”) activatable adhesive formulation.
Additional aspects of the preferred embodiment adhesives are as follows. A typical range of average molecular weight of the adhesive base polymer is from about 10,000 Daltons to about 150,000 Daltons. A preferred range is from about 15,000 Daltons to about 100,000 Daltons, with a range of from about 20,000 Daltons to about 40,000 Daltons being most preferred. Polymers with lower molecular weight are generally preferred because such polymer can be activated faster than a corresponding base polymer having a higher molecular weight.
The adhesive base polymers also exhibit certain glass transition temperatures, Tg. Although the Tg of the base polymer depends upon pressure and temperature requirements of the process, and pressure and temperature conditions which the product may encounter, a typical Tg range is from about 20° C. to about 100° C. A preferred Tg range is from about 55° C. to about 80° C. And, a most preferred range for the glass transition temperature Tg of the base polymer is from 60° C. to 75° C.
It is also preferred that when forming the adhesives, after melting, the plasticizer remains in a liquid or flowable form for an extended period of time. The temperatures at which the plasticizers exist in the liquid or flowable state are typically from 50° C. to 120° C.
As a result of the particular formulation and selection of components, many of which have particular properties and characteristics, the activated preferred embodiment adhesives remain tacky in a temperature about −10° C. and above. The activated preferred adhesives typically remain tacky for time periods of from about 0.1 seconds to about 2 weeks. However, it will be appreciated that the invention is not limited to these particular time periods. For example, linerless label adhesives can be formulated which remain tacky for periods longer than 2 weeks. Many of the activated preferred linerless label adhesives exhibit remarkably long open times, i.e. the period of time during which the adhesive is in a tacky state.
By controlling various factors including the molecular weight and molecular weight distribution of the base polymer, as well as the level of the multifunctional monomer of the base polymer by using a combination of multifunctional monomer and chain transfer material, a heat switchable activatable linerless label adhesive that has superior properties of fast activation, high tack, long open time, and long lasting clarity is obtained. Upon heating, the activatable linerless label adhesive behaves as a typical pressure sensitive adhesive, and the property of tack can be maintained for a prolonged period of time, which allows the adhesive material to flow or wet-out on the targeted substrate surface for enhancing the adhesion. Furthermore, the linerless label adhesive materials in this invention are inherently activatable with Near IR radiation, which leads to a short activation time for fast line speed.
The base polymers of the preferred adhesives typically exhibit a polydispersity index of from about 2.0 to about 10.0, and preferably from 2.0 to 4.0. However, it will be appreciated that the base polymers of the activatable linerless label adhesives of the invention include polymeric systems exhibiting polydispersities less than 2.0 and greater than 10.0.
To activate and apply the linerless labels 100 to the item, the linerless labels 100 are typically placed on a delivery device, or actuator. These delivery devices include blower systems (see U.S. Pat. No. 4,784,714 to Shibata), conveyor belts (see U.S. Pat. No. 5,895,552 to Matsuguchi), paddles (see U.S. Pat. No. 5,922,169 to Chodacki), plungers (see U.S. Pat. No. 6,006,808 to Ewert et al.), carrier sheets (see U.S. Pat. No. 7,029,549 to Von Folkenhausen et al.), vacuum drums (see U.S. Pat. No. 6,899,155 to Francke et al.), rollers (see U.S. Pat. No. 5,964,975 to Hinton), and vacuum heads or belts (see U.S. Pat. No. 6,471,802 to Williamson). The items to which the linerless label 100 can be applied can include, for example, boxes, parcels, envelopes, pouches, bags, vessels, containers, cans, and bottles.
The delivery device receives the linerless label 100, then transports the linerless label 100 such that the adhesive 120 side of the linerless label 100 is exposed to an activation device, which employs an activation scheme as previously noted. In an embodiment, the activation scheme can include the exposure of the linerless label 100 to IR energy having a peak wavelength from approximately 0.8 μm to approximately 3 μm. Multiple delivery devices can be used in sequence to transport the linerless label 100 from its unactivated state to attachment to the item. For example, the delivery devices can include one or more actuators that are configured to receive the linerless label 100, transport the linerless label 100 through the radiant energy, and transport the linerless label 100 to a position where the linerless label 100 is applied to the item. In an embodiment, linerless labels 100 are activated using a ten-inch long NIR unit by Advance Photonics Technology AG of Bruckmuhl, Germany with emitters, units or lamps that each are configured to emit from approximately 200 kW/m2 to 800 kW/m2 irradiance delivering up to 4000 kW/m2 mostly around the peak wavelength of 0.8 μm. The same activation rates in excess of 200 labels/minute were also obtained using a Short IR (SWIR) with peak wavelength of 1.2 μm, a Fast Mid Wave IR (FMWIR) with peak wavelength of 1.5 μm and a Mid Wave IR (“MWIR”) unit with peak wavelength of 23 μm by Heraeus Noblelight GmbH of Keinostheim, Germany that include 6 to 8 twin tube emitters with short response times of less than 11 to 2 seconds. Short response times are advantageous because the units, i.e., the energy sources that are part of the activation devices, can be turned ON and OFF at a fast rate, for example, the rate of once every second or two seconds. Energy savings result from avoiding the need to leave the units ON continuously. Because of the high energy density provided by the units, the units need only be turned ON for a limited period of time to activate the adhesive 120. Depending on the dimensions of each linerless label 100, exposure times of the adhesive to the radiation can be for less than one second, and typically range from approximately 0.1 second to approximately 0.5 second. The SWIR and FMWIR are narrower than carbon types giving higher energy densities. The selection of emitter depends upon a variety of factors, and particularly is a tradeoff between high energy densities, e.g. highest absorption by the adhesive 120 and lowest absorption by the printed indicia, or controlled penetration into the structure and fastest ON/OFF cycles. Other factors especially relating to safety of using these high power emitters 148 (
Another advantage of such the first system 140 is that the system allows for short changeover times. Current cut-and-stack technology requires special glue application feet that must match the size of the cut-and-stack label, and must be adjusted to properly register with a cut-and-stack label area and not cause cut-and-stack edge bleeding of the cut-and-stack adhesive. A typical change-over time for such a process is up to eight hours. In example embodiments of the present invention, the change over-time can range from, for example, approximately one hour to approximately two hours. Accordingly, change over-time is greatly reduced.
With more particular reference to the TAM unit 142,
The quartz glass 149 is to be of a type that allows most of the radiation energy to pass through it, more particularly at least about 75% transmission of energy from an IR emitter, typically at least about 80%, at least about 85% or at least about 92% IR energy transmission. Suitable in this regard employs a General Electric (GE) 214 quartz glass, which has been found to provide the best results of refraction, thermal conductivity and most importantly its large IR transmission spectrum. The GE 214 glass is found to pass substantially all of the radiation energy from the emitters 148.
It is preferred that the emitters 148 (
Vertical or normal orientation of the emitters 148 (
Preferred emitters 148 (
Software for the control logic is designed to read the minimum and maximum temperatures on a P&A adhesive and set the power to the emitters 148 (
The radiation energy of the emitters 148 (
1. Efficiency of the emitters 148 (
2. Transmission of emitter light by the quartz glass 149 (
3. The distance between the emitters 148 (
4. How close the emitters 148 (
5. Portion of the radiated energy that strikes the P&A label, which depends on the quality of the reflectors and the angle of reflected light, the distance between the emitters 148 (
6. Exposure time during which the P&A label receives radiated energy, i.e. speed of the machine in printing, activating and applying the P&A labels.
It will be appreciated that the adhesive 120 (
The following parameters contribute to high speed activation of the linerless labels 100 (
It is possible to calculate available energy and needed energy for high-speed activation of the labels 100 (
Continuing with these calculations,
Abs=log(Iincident/Ireflected)
I
absorbed
=I
incident
−I
reflected
Abs˜=0.35 in
The radiant flux, Qrl, received on the linerless label 100 (
Q
rl
=F
1-2
*F
2-3
*F
3-4*((σ*ε*A*T4)/(1−fc)
Where σ is Stephen-Boltzmann coefficient and ε the average emissivity of emitters 148 (
Q
act
=Q
rl
−Q
c
−Q
r
Q
effective=1200*0.55=660 Watt absorbed power
E
p=0.9*Cppaper*(Tact−Tamb)
E
t
=E
p
+E
1
t
exp
=E
t(J)/Qeffective(Watts)
t
exp=185/660=0.28 sec.
Lmax=2×L+V×(2.5 sec−Tcut)
A linerless laminate roll attributes discussed herein afford a unique advantage compared to current conventional thermal transfer roll labels in being able to afford certain features as follows. This has almost 60% more material length for a same size roll and more than 60% more calculated linerless labels 100 (
Turning now to a printed label thermal transfer media in greater detail, an image is created by transferring colorant pixel-wise from a thermal transfer ribbon. Thermal transfer ribbons typically consists of a polyethylene terephthalate film coated with thermal transfer inks. These thermal transfer inks are in a solid phase at room temperature and transfer to the receiving layer under heat and pressure. The colorants used in the thermal transfer ribbons can be dye or pigment based. These colorants can be suspended in a thermal solvent (solvent which is solid at room temperature, but melts at higher temperature and is a good solvent for the dye, examples are high molecular waxes) or could be in a thermoplastic polymer matrix (example of polymer matrix are acrylic matrix, vinyl matrix etc).
The thermal transfer ribbon is in direct contact with the printed label thermal transfer media, this putting some special requirements on the printed label thermal transfer media. The printed label thermal transfer media needs to be very smooth to obtain intimate contact between the thermal transfer ribbon and the printed label thermal transfer media. The thermal conductivity of the printed label thermal transfer media should be such that heating is confined in a top layer of the printed label thermal transfer media. An example of one such structure is a colorant receiving layer, below which is an insulating layer with a back coating of an antistatic layer. Many variants of this multilayer structure are possible, with the insulating layer being made of voided polypropylene, such as Yupo/Kimdura with Tio2 for opacity. The voided polypropylene provides the insulating behavior as well as a cushion between a rigid thermal print head and a backup roller. In an embodiment, the printed label thermal transfer media is formed by air filled glass beads in a polymer matrix, however, below this an elastic layer that is needed to provide a cushion between the rigid thermal print head and the backup roller (Fuji film). Often calendared paper is used as a media, which may or may not be coated with an ink receiving layer. The porosity of the calendared paper serves as the insulating layer.
The colorant receiving layer is formulated to provide good adhesion to the thermal transfer ink as well as provide a good clean fracture at the end of the edge 220 (
A multilayer media structure can be generated by multilayer coating process or by transfer coating the colorant receiving layer onto the insulation layer and bonding the colorant receiving layer to the insulation layer using the adhesive 120 (
In the TAM unit 142 (
Turning now to the operational logic of the machine and system, reading a bar code on the linerless laminate roll will give certain number of informational pieces to the system, for instance the activation temperature needed to set. It also gives general information on when and where the adhesive 120 (
Concerning operational logic for speed increase, cardboards are tough substrates for activated adhesives, and an example is provided for box applications. An optimal sequence of print, cut, activation and application steps while the label travels through the machine is used to increase the box labeling speed to higher numbers (as shown on
The following abnormal situations may happen while labeling cardboard boxes. The machine and system will respond as indicated by operation of the control logic. In one situation, a box conveyor is stopped or there is no box detected on the box conveyor. There are at least two cases to take care of:
1. The machine was waiting for a next box to come when this situation happened. The system will continue to wait for the next box to come, and it goes to its idle mode while an application sensor is watching for the next box.
2. The machine had detected the next box, started to print and activate a linerless label 100 (
In the event of loss of electric power, depending on what the system was doing several different responses are possible:
1. The machine was waiting for the next box and was in idle mode. It will restart after power is established. The machine will ready to work after the TAM unit 142 (
2. The machine had detected the next box and had started to print and activate when power went off. If the linerless label 100 (
3. The machine had detected the nest box and had started to print and activate when power went off. If the linerless label 100 (
4. Another case is when the linerless label 100 (
Concerning the control logic used to manage the system after a failed emitter, the machine detects that the failed emitter is out of order and warns the user with the general warning and an alarm on a TAM unit panel. If the system is in idle mode, it will not let it operate until the failed emitter or emitters are replaced and alarm is cleared.
If the machine is running and one emitter 148 (
Multiple application systems can be employed as depicted as a roll-on applicator 143 in
Another application system is illustrated in
A vacuum plate can be provided instead of the soft belt 181 for the tamp-on applicator system.
Another type of applicator can be of the blow-on variety such as shown in
Test results show that the spectra of IR from both NIR and MWIR radiations are highly effective at coupling with the dicyclohexyl phthalate based adhesive 120 (
The systems for applying a linerless label 100 (
The preferred system also comprises a cutter 252 (
The thermal activation unit 200 (
The system may include additional sensors and control provisions. For example, the system may include one or more signal interfaces between any of the printer unit 250 (
The above systems, machines and methods achieve rates for applying the linerless labels 100 (
NIR energies are efficient tools for activating the adhesives 120 (
Referring to
The facestock layer 110 can be constructed from any material that is receptive to the ink that is used to print the indicia 130 on the facestock layer 110 and the face 210. Example materials for the facestock layer 110 include paper, polymer films, metalized paper, paper backed foil, and metallic foils. Referring additionally to the example embodiment illustrated in
Referring additionally to the example embodiment illustrated in
Referring additionally to the example embodiment illustrated in
Various embodiments of the invention can have a variety of sizes and shapes. For example, referring additionally to
The various labels and label systems described herein may further comprise one or more barrier coats or layers or primer coats or layers. Such coats or layers are beneficial during printing stages, particularly those employing direct thermal printing. Generally, a barrier coat prevents discoloration of the facestock 110 (
In several of the preferred embodiment adhesive formulations, glyceryl tribenzoate is used as the plasticizer and has a peak melting temperature at 72° C., a range of 68° C.-72° C. Another plasticizer is dicyclohexyl phthalate, which has a peak melting temperature at 63° C. Once the adhesive 120 (
The present invention adhesives 120 (
Additionally, the barrier layer 620 can enhance the anchorage of the adhesive 610 with a wider drying temperature range during adhesive coating process. In addition, the barrier layer 620 also serves as a guard to minimize bleeding of plasticizer from the adhesive 610 to the paper facestock. Furthermore, the barrier layer 620 can have a thickness of less than 12 μm and have the glass transition temperature lower than 80° C.
Referring to
In certain embodiments, and as described herein, carbon black or other like agent(s), are incorporated into one or more layers of the layered assembly 600 to promote activation of the adhesive 610. Generally, the incorporation of carbon black reduces energy consumption for the activation process. Reduced energy consumption may be exhibited or result in cost savings, higher processing speeds, and/or further promote “green” aspects of the technology. Moreover, incorporating carbon black in one or more layers or the layered assembly 600 enables isolation of other radiation sources 200 (
The carbon black or other alternate mediums, when incorporated into the layered assembly 600 promote energy absorption of the material, thereby leading to improved efficiencies. The carbon black can be incorporated into any layer of the layered assembly. However, it is generally preferred that the carbon black be incorporated within the adhesive 610. However, the invention is not limited to such and includes the incorporation of carbon black in other layers in addition to or instead of the adhesive 610. For example, carbon black can be incorporated in a barrier layer 620. It is also contemplated that carbon black or other like agent(s) can be incorporated in the primer layer. If carbon black is used in the primer or barrier layer 620, it can be used at the previously noted concentrations as when incorporated in an adhesive 610. However, for many applications, it is preferred to use carbon black at higher concentrations such as about 0.1%.
It is noted that other agents can be used instead of or in addition to carbon black for promoting energy absorption. Non-limiting examples of such other agents include various organic dyes, coloring agents, and pigments; and various inorganic dyes, coloring agents, and pigments. It will be understood that a wide array of inks or other agents could be used. Moreover, combinations of any of these can be used. It is contemplated that combinations of agents can be incorporated in multiple or different layers of the layered assembly 600. For example, carbon black can be incorporated into the adhesive 610 and one or more organic and/or inorganic dyes can be incorporated in a barrier layer 620.
The concentration of the carbon black or other like agent(s) in the layer of interest can vary, so long as the concentration beneficially promotes energy absorption into that layer and an increase in temperature. For example, when incorporating carbon black into the adhesive 610 or barrier layer 620, generally the concentration is at least about 0.1%, and preferably at least about 1%. The upper limit depends on numerous factors.
The present invention also provides various systems using the activatable adhesives 610 (
Another preferred embodiment system comprises an activatable label 100/480/500 (
The adhesives 610 (
The various layered arrays and label assemblies 600 (
Exemplary procedures for preparing the base polymer noted in Table 2, are as follows:
An emulsion adhesive polymer base is prepared by emulsion polymerization from a plurality of monomers consisting of 37.2% butyl acrylate, 29.3% styrene, 29.3% methyl methacrylate, 1.7% methacrylic acid, and 2.5% acrylic acid, based on the weight of all monomers, with 0.06% by weight of n-dodecy mercaptan added as a chain transfer agent. A one-liter, jacketed, cylindrical reaction flask equipped with a four-neck flask head was fitted with a steel stirring rod with multiple steel blades, a reflux condenser, a thermometer, and a nitrogen inlet tube. The stirring speed is set at approximately 126 rpm, and the reaction temperature was set at 80° C. A reactor pre-charged solution is made by dissolving 1.0 g of HITENOL BC-10 (Dai-lchi Kogyo Seiyaku Co., Ltd. of Kyoto, Japan) surfactant in 100 g deionized water. A pre-emulsion feed soap solution is formed by dissolving 2.0 g HITENOL BC-10 and 105 g deionized water. A monomer mix is made up with 140 g of n-butyl acrylate, 110 g styrene, 110 g of methyl methacrylate, 6.5 g of methacrylic acid, 9.1 g of acrylic acid, and 0.24 g of n-dodecyl mercaptan. The monomer mix is added to the pre-emulsion solution under stirring for 10 min. An initiator solution A is prepared by dissolving 0.75 g potassium persulfate in 67 g of deionized water; solution B is made by dissolving 0.5 g of potassium persulfate in 67 g of deionized water. A kickoff initiator solution is prepared by dissolving 0.75 g of potassium persulfate in 38 g of water. The reactor pre-charged solution is introduced to the glass reactor, which has been flushed with nitrogen. The kickoff initiator solution is added when the solution temperature reached 80° C. After 5 minutes, 20 g of the pre-emulsion solution was introduced into the reactor. Upon observing polymerization, the pre-emulsion solution and initiator solution A are started. Initiator solution B is fed at the end of solution A. The pre-emulsion solution feed is completed in a 4 hour period, and the initiator solution A and B feeds are completed in 4 hours and 15 minutes. Polymerization continues for another 30 minutes after completion of the initiator solution B feed. The polymerization temperature is maintained at 80° C. during the polymerization. Polymerization of the monomer mixture yields a polymer latex, which can be formulated further for linerless adhesives, and which can be coated on the desired substrates.
The same polymerization procedure that is used in Example 1 is used, except that the monomers used for the polymerization are used in the following weight percentages. 48.0% butyl acrylate, 23.9% styrene, 23.9% methyl methacrylate, 1.7% methacrylic acid, and 2.5% acrylic acid.
Preparation of an exemplary white heat-activated adhesive is as follows. A switchable adhesive formulation is prepared from the noted adhesive polymer base by blending with a selected plasticizer and tackifier at room temperature for enough time to ensure a homogenous composition. Typically, the preferred melting point of such solid plasticizer is above 40° C. In this example, ground plasticizer dicyclohexyl phthalate or U250M supplied by Unitex Corp. of Greensboro, N.C. is used. The melting point of U250M is in the range of 63° C. to 65° C. The exemplary tackifier is TACOLYN 3400 (softening point 92° C.) which is a resin dispersion by Eastman Chemical Company of Kingsport, Tenn. TACOLYN 3400 is a resin ester dispersion. More specifically, TACOLYN 3400 is an aqueous, 55% solids, solvent-free anionic rosin ester dispersion prepared from a highly hydrogenated, high softening point resin. Not to be held to any particular theory, it is believed that when the white heat-activated adhesive is irradiated, the selected plasticizer is melted. The small plasticizer molecules are able to slip in between the adhesive base polymer chains to function as a “lubricant”, even after the polymer cools. As a result, the free volume of the polymer is increased, or the glass transition temperature (Tg) of the adhesive polymer base is lowered, which leads to highly flexible adhesive coating. Advantageously, in certain exemplary embodiments, the adhesive does not include carbon black, graphite, ink(s), dye(s), pigment(s), and/or colorant(s). However, other exemplary embodiments of the adhesive include the use of such agents.
An emulsion adhesive polymer base is prepared by emulsion polymerization from plurality of monomers consisting of 13.15% of butyl acrylate, 75.16% of styrene, 0.12% of methyl acrylate, 1.30% of merthacrylic acid, 1.64% of acrylic acid, 3.67% of methyl methacrylate, 1.01% of SR 206 (Sartomer Company Inc., Exton, Pa.) and 0.50% of SR 306 (Sartomer Company Inc., Exton, Pa.), based on the weight of all monomer and chain transfer agent, with 3.45% by weight of n-dodecyl mercaptan added as a chain transfer agent.
A one-liter, jacketed, cylindrical reaction flask equipped with a four-neck flask head was fitted with a steel rod with multiple blades, a reflux condenser, a thermometer, and a nitrogen inlet tube. The stirring rate is set at approximately 126 rpm.
A reactor pre-charge solution is made by dissolving 2.00 g of Disponil FES-77 (Cognis Corp., Cincinnati, Ohio), 0.60 g of Surfynol 485 (Air Products and Chemicals, Inc., Allentown, Pa.) and 0.01 g of Drewplus L-198 (Ashland, Columbus, Ohio) in 166.30 g of deionized water.
A pre-emulsion feed soap solution is formed by dissolving 16.30 g of Disponil FES-77, 5.85 g of Surfynol 485 and 2.94 g of Aerosol OT-75 and 0.01 g of Drewplus L-198 in 200.00 g of deionized water. A monomer mix is made up with 67.33 g of butyl acrylate, 0.60 of methyl acrylate, 384.84 g of styrene, 18.78 g of methyl methacrylate, 6.66 g of methacrylic acid, 8.39 g of acrylic acid, 2.57 g of SR-306, 5.17 g of SR-206 and 17.68 g of n-dodecyl mercaptan.
The monomer mix is added to the pre-emulsion solution under stirring for 10 minutes to form a white milky emulsion. An initiator is prepared by dissolving 1.34 g of potassium persulfate in 64.66 g of deionized water. A kickoff solution is prepared by dissolving 1.13 g of potassium persulfate in 30 g of deionized water. The reactor pre-charge solution is introduced to the reactor which has been flushed with nitrogen.
The kickoff initiator solution is added to the reactor when the solution reached 78° C. and the reaction temperature is raised to 86° C. After 2 minutes, the pre-emulsion solution is introduced to the reactor and is completed in 240 minutes. After 45 minutes from starting of adding the pre-emulsion solution, the initiator solution is added to the reactor and is completed in 210 minutes. At this point 2.25 g of 19% ammonia water is added to the reactor. After 45 minutes, the temperature of the reactor is lowered to 75° C. Another 2.25 g of 19% ammonia water, 0.6 g of t-butyl hydrogen peroxide and 0.2 g of sodium hydroxymethanesulfinate are added to the reactor. The temperature of the reactor is further lowered to 35° C. To the resulting mixture, 0.2 g of Drewplus L-198, 0.05 g of Acticide GA (Thor Specialties Inc., Trumbull, Conn.) and 2.23 g of deionized water are added. By the this procedure, a polymer latex is obtained in around 50.5% solids content and in pH around 6.5 to 7.0 and is ready to be used for adhesive formulation.
An emulsion-based adhesive system “A” was prepared by using the acrylic emulsion based polymer formed in Example 3. Specifically, the adhesive system was formed as set forth in Table 7.
Specifically, the adhesive system is prepared by combining 25.5 parts by weight of the polymer produced in Example 3 with 66 parts by weight of UNIPLEX 260 dispersion and 8.5 parts by weight of Super Ester E-650 dispersion (Tackifier) (Arakawa Chemical of Osaka, Japan). The UNIPLEX 260 dispersion was prepared by milling UNIPLEX 260, water, dispersant and defoamer, and serves as the plasticizer. And the Super Ester E-650 component serves as the tackifier.
This emulsion based adhesive is stable, can be directly coated onto papers or films and dried in an air-circulated oven up to 56° C. for 15 minutes without any sign of activation. The dried adhesive shows very good anchorage to primed or unprimed papers and film and passes blocking test at 45° C. under 15 pounds per square inch (psi) pressure (about 103,421 Newton/m2) but did not pass the blocking test at 55° C. under 15 psi pressure. Peel strength test data were mixed, and this formulation gives an estimated 23.2% biobased “new carbon” content in the adhesive. Further details are found in the discussion herein relating to
This type of adhesive exhibits excellent tack and good adhesion to non-polar surfaces and cardboards as well as remains very tacky greater than 48 hours and clear for a long period of time after activation under one or more IR emitters for 5 to 10 seconds.
An emulsion-based adhesive system “B” was prepared by using the acrylic emulsion based polymer formed in Example 3. Specifically, the adhesive system was formed as set forth in Table 8.
Specifically, the adhesive system is prepared by combining 25.5 parts by weight of the polymer produced in Example 3 with 66 parts by weight of UNIPLEX 260 dispersion and 8.5 parts by weight of Tamanol E-102A dispersion available from Arakawa Chemical of Osaka, Japan. The UNIPLEX 260 dispersion was prepared by milling UNIPLEX 260, water, dispersant and defoamer, and serves as the plasticizer. And the Tamanol E-102A component serves as the tackifier.
This emulsion based adhesive is stable, can be directly coated onto papers or films and dried in an air-circulated oven up to 56° C. for 15 minutes without any sign of activation. The dried adhesive shows very good anchorage to primed or unprimed papers and film and passes blocking test at 55° C. under 15 psi pressure (about 103,421 Newton/m2). Peel strength test data were very good, and this formulation gives an estimated 23.2% biobased “new carbon” content in the adhesive. Further details are found in the discussion herein relating to
This type of adhesive exhibits excellent tack and good adhesion to non-polar surfaces and cardboards as well as remains very tacky greater than 48 hours and clear for a long period of time after activation under one or more IR emitters for 5 to 10 seconds.
An emulsion-based adhesive system “C” was prepared by using the acrylic emulsion based polymer formed in Example 3. Specifically, the adhesive system was formed as set forth in Table 9.
Specifically, the adhesive system is prepared by combining 25.5 parts by weight of the polymer produced in Example 3 with 66 parts by weight of UNIPLEX 260 dispersion and 8.5 parts by weight of Super Ester E-730 dispersion available from Arakawa Chemical of Osaka, Japan. The UNIPLEX 260 dispersion was prepared by milling UNIPLEX 260, water, dispersant and defoamer, and serves as the plasticizer. And the Super Ester E-730 component serves as the tackifier.
This emulsion based adhesive is stable, can be directly coated onto papers or films and dried in an air-circulated oven up to 56° C. for 15 minutes without any sign of activation. The dried adhesive shows very good anchorage to primed or unprimed papers and film and passes blocking test at 55° C. under 15 psi pressure (about 103,421 Newton/m2). Peel strength test data were very good, and this formulation gives an estimated 23.2% biobased “new carbon” content in the adhesive. Further details are found in the discussion herein relating to
This type of adhesive exhibits excellent tack and good adhesion to non-polar surfaces and cardboards as well as remains very tacky greater than 48 hours and clear for a long period of time after activation under one or more IR emitters 148 (
An emulsion-based adhesive system “D” was prepared by using the acrylic emulsion based polymer formed in Example 3. Specifically, the adhesive system was formed as set forth in Table 10.
Specifically, the adhesive system is prepared by combining 25.5 parts by weight of the polymer produced in Example 3 with 66 parts by weight of UNIPLEX 250 dispersion and 8.5 parts by weight of Super Ester E-650 dispersion available from Ara kawa Chemical of Osaka, Japan. The UNIPLEX 250 dispersion was prepared by milling UNIPLEX 250, water, dispersant and defoamer, and serves as the plasticizer. And, the Super Ester E-650 component serves as the tackifier.
This emulsion based adhesive is stable, can be directly coated onto papers or films and dried in an air-circulated oven up to 56° C. for 15 minutes without any sign of activation. The dried adhesive shows very good anchorage to primed or unprimed papers and film and did not pass the blocking test at 45° C. under 15 psi pressure (about 103,421 Newton/m2). Peel strength test results were reasonable but not exceptional. This formulation gives a biobased “new carbon” content estimate of 9.5% in the adhesive. Further details are found in the discussion herein regarding
This type of adhesive exhibits excellent tack and good adhesion to non-polar surfaces and cardboards as well as remains very tacky greater than 48 hours and clear for a long period of time after activation under one or more IR emitters 148 (
An emulsion-based adhesive system “E” was prepared by using the acrylic emulsion based polymer formed in Example 3. Specifically, the adhesive system was formed as set forth in Table 11.
Specifically, the adhesive system is prepared by combining 25.5 parts by weight of the polymer produced in Example 3 with 66 parts by weight of UNIPLEX 250 dispersion and 8.5 parts by weight of Tamanol E-102A dispersion available from Arakawa Chemical of Osaka, Japan. The UNIPLEX 250 dispersion was prepared by milling UNIPLEX 250, water, dispersant and defoamer, and serves as the plasticizer. And, the Tamanol E-102A component serves as the tackifier.
This emulsion based adhesive is stable, can be directly coated onto papers or films and dried in an air-circulated oven up to 56° C. for 15 minutes without any sign of activation. The dried adhesive shows very good anchorage to primed or unprimed papers and film and marginally passed the blocking test at 45° C. under 15 psi pressure (about 103,421 Newton/m2) but did not pass the blocking test at 55° C. under 15 psi pressure. Peel strength test results were reasonable but not exceptional. This formulation gives a biobased “new carbon” content estimate of 9.5% in the adhesive. Further details are found in the discussion herein regarding
This type of adhesive exhibits excellent tack and good adhesion to non-polar surfaces and cardboards as well as remains very tacky greater than 48 hours and clear for long period of time after activation under one or more IR emitters 148 (
An emulsion-based adhesive system “F” was prepared by using the acrylic emulsion based polymer formed in Example 3. Specifically, the adhesive system was formed as set forth in Table 12.
Specifically, the adhesive system is prepared by combining 255 parts by weight of the polymer produced in Example 3 with 66 parts by weight of UNIPLEX 250 dispersion and 85 parts by weight of Super Ester E-730 dispersion available from Arakawa Chemical of Osaka, Japan. The UNIPLEX 250 dispersion was prepared by milling UNIPLEX 250, water, dispersant and defoamer, and serves as the plasticizer. And, the Super Ester E-730 component serves as the tackifier.
This emulsion based adhesive is stable, can be directly coated onto papers or films and dried in an air-circulated oven up to 56° C. for 15 minutes without any sign of activation. The dried adhesive shows very good anchorage to primed or unprimed papers and film and marginally passed the blocking test at 45° C. under 15 psi pressure (about 103,421 Newton/m2) but did not pass the blocking test at 55° C. under 15 psi pressure. Peel strength test results were reasonable but not exceptional. This formulation gives a biobased “new carbon” content estimate of 9.5% in the adhesive system. Further details are found in the discussion herein regarding
This type of adhesive exhibits excellent tack and good adhesion to non-polar surfaces and cardboards as well as remains very tacky greater than 48 hours and clear for a long period of time after activation under one or more IR emitters 148 (
The adhesive samples of Examples 4 through 9 are NIR to MWIR radiation activatable. Blocking and peel adhesion tests were performed and statistically analyzed, and the results are listed in the table of
The adhesive was coated at an approximate coat weight in the specified range of 20 gsm to 40 gsm onto the selected paper facestock. A barrier coating is coated on the paper if needed. The coated materials are dried at 50° C. for 10 minutes. The resulting construction was die-cut into 25×204 mm (1×8 inch) sized strips. The strips were then subjected to an activation thermally via Mid Wave IR, and applied centered along the lengthwise direction to 50×152 mm (2×6 inch) brightly annealed, highly polished stainless steel test panels, or a paper cardboard, and rolled down using a 2 kg (4.5 lb), 65 shore “A” rubber-faced roller, rolling back and forth once, at a rate of 30 cm/min (12 in/min). The samples were conditioned for either 20 minutes or 24 hours in a controlled environment testing room maintained at 23° C. (73° F.) and 50% relative humidity. After conditioning, the test strips were peeled away from the test panel in an Instron Universal Tester according to a modified version of the standard tape method Pressure-Sensitive Tape Council, PSTC-1 (rev. 1992), Peel Adhesion for Single Coated Tapes 180° Angle, where the peel angle was either 180° or 90°, i.e., perpendicular to the surface of the panel, at a rate of 30 cm/min (12 in/min). A force to remove the adhesive test strip from the test panel was measured in lbs/in. All tests were conducted in triplicate.
The conducted peel tests are known as 90 RT “instant” Average Peel, 90 RT Average Peel, and 90 LT 10C Average Peel. All results are reported in pounds per inch, and all samples showed adhesive transfer.
Data in
A stack of 3 to 5 linerless labels in 2 inch by 2 inch is placed on a flat metal block in an oven with pre-set oven temperature, humidity and duration. A piece of the facestock in 2 inch by 2 inch is placed in between the metal surface and the label stack. On the other side of label stack, a mirror finishing aluminum block in 1 inch by 1 inch is placed on the top of label stack. Then a metal block of desired weight is placed on the top of aluminum block.
Upon the completion of test duration, the label stack is removed from the oven and is placed under ambient conditions for at least 30 minutes before inspection. Each label is separated from the stack manually and is inspected under light to check both adhesive side and printing side. Notes are taking for any adhesive coating transfers from adhesive side to printing side, or adhesive side sticks to print side to form a block of label stack. To those label shows no transfer by naked eye, label is further activated by IR lamp and the print side is inspected again under light to see if any shining spot which indicates the existing of adhesive transfer.
The following observations are made from the date of
It will be understood that any embodiment, aspect, or detail thereof can be used with any other embodiment, aspect, or detail thereof described herein. Thus, the various adhesive systems and adhesive base polymers described herein can be used in conjunction with any of the labels, label assemblies, systems, and methods described herein.
It will thus be seen according to the present invention a highly advantageous linerless labels and activatable adhesives, systems, machines, and methods has been provided. While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it will be apparent to those of ordinary skill in the art that the invention is not to be limited to the disclosed embodiment, and that many modifications and equivalent arrangements may be made thereof within the scope of the invention, which scope is to be accorded the broadest interpretation of the appended claims so as to encompass all equivalent structures and products.
The inventors hereby state their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of their invention as it pertains to any apparatus, system, method or article not materially departing from but outside the literal scope of the invention as set out in the following claims.
