PSA compositions with ultra-low temperature properties

Abstract

Pressure-sensitive adhesives (PSAs) comprise two different acrylate polymers and a metal chelating agent to prepare the PSA. PSAs produced according to the methods described herein can be used over a wide operating temperature range, i.e., -90°C to 40°C, for example -40°C to 37°C. When bonded to a substrate, these PSAs exhibit optimal tack and cohesion, and / or resistance to warm water baths.

Description

Technical Field

[0001] This disclosure generally relates to pressure-sensitive adhesives (PSAs), particularly PSAs with improved low-temperature performance and improved water resistance. This application also relates to labels containing improved PSAs and methods for producing PSAs and labels. Background Technology

[0002] PSA is known to provide instantaneous adhesion to substrates under pressure. PSA is generally easy to handle in solid form and has a long shelf life, making it widely used in applications such as self-adhesive labels. However, labeling cryogenic products, such as blood packages maintained at ultra-low temperatures below -40°C, has always been challenging due to the stringent requirements of these applications. For example, labels must be able to adhere to frozen blood packages and their tubing at these ultra-low temperatures. Labeled packaging also needs to be stored at ultra-low temperatures for extended periods. In use, these blood packages require pre-thawing at relatively low temperatures, such as 2-4°C (pre-thawing stage), followed by thawing at 37°C, for example, by immersion in a warm water bath (thawing stage). These procedures subject the labels to a variety of temperatures, including harsh, ultra-low temperatures, and adverse underwater environments. During these procedures, the labels often become loose and separate from the packaging.

[0003] Despite industry efforts to create adhesives that function under these conditions, the results remain far from ideal. For example, these adhesives must be manufactured in a way that keeps them extremely flexible to maintain their ability to adhere to packaging at extremely low temperatures. As a result, the adhesive often overflows after application to the substrate, negatively impacting print quality. During the pre-thawing and thawing stages, labels on packaging tubes often stretch and become detached from the packaging. Furthermore, label application at extremely low temperatures is cumbersome because the frozen layer on the substrate must be removed from the packaging before labeling can be applied. Therefore, despite these disadvantages, there is still a need to produce PSAs that can achieve their intended purpose. Attached Figure Description

[0004] Figure 1 The image shows a blood package with a label containing the PSA of the present invention. Arrows indicate labels already affixed to the package and tubing. Summary of the Invention

[0005] This disclosure provides a pressure-sensitive adhesive, comprising: a polyacrylate-based polymer having a certain glass transition temperature, a polyacrylate tackifier having a certain glass transition temperature, and a metal chelating crosslinking agent, wherein the glass transition temperatures of the polyacrylate tackifier and the polyacrylate-based polymer are both below 90°C, and wherein the glass transition temperature of the polyacrylate-based polymer is lower than the glass transition temperature of the polyacrylate tackifier.

[0006] In some embodiments, the pressure-sensitive adhesive is a solvent-based PSA. In some embodiments, the glass transition temperature (TVT) of the polyacrylate-based polymer ranges from -99°C to -20°C. In some embodiments, the glass transition temperature (Tg) of the polyacrylate tackifier is greater than -30°C, for example, ranging from -30°C to 90°C. In some embodiments, the glass transition temperature (Tg) of the polyacrylate-based polymer ranges from -50°C to -35°C. In some embodiments, the Tg of the polyacrylate-based polymer is 5°C to 100°C lower than that of the polyacrylate tackifier.

[0007] In some embodiments, the molecular weight of the polyacrylate-based polymer is greater than that of the polyacrylate tackifier. In some embodiments, the polyacrylate-based polymer has a weight-average molecular weight (Mw) in the range of 200,000 to 1,500,000 g / mol.

[0008] In some embodiments, the polyacrylate-based polymer is present in an amount of 30 wt.% to 99.9 wt.% based on the total solid weight of the pressure-sensitive adhesive.

[0009] In some embodiments, the polyacrylate-based polymers are selected from Taizhou Yade Adhesive's 3-4229, 3422, 3468, and 3462A; Toyo Ink's BPS5296, BPS5330W, and BPS5448; Eternal's Etrac 77313 and Etrac 7043; Henkel's Ultra Reclo 109A and Ultra Reclo 236A; and YASUSA's Y-1220 and Y-180314X.

[0010] In some embodiments, the polyacrylate tackifier has a weight-average molecular weight of 10,000 to 300,000 g / mol. In some embodiments, the polyacrylate tackifier is present in an amount of 0.5 wt.% to 30 wt.% based on the total solids weight of the pressure-sensitive adhesive. In some embodiments, the polyacrylate-based polymer comprises less than 2 wt.% rosin resin, aziridine, or epoxy resin, or combinations thereof. In some embodiments, the pressure-sensitive adhesive exhibits a peel strength greater than 11.5 N / inch on polyvinyl chloride, as measured by FINAT test method 1 (2018).

[0011] In some embodiments, according to FINAT 2018, the pressure-sensitive adhesive exhibits shear strength greater than 5,000 minutes (e.g., greater than 8,000 minutes) on stainless steel. In some embodiments, the pressure-sensitive adhesive has a peel strength of 5 N / inch to 20 N / inch on polyvinyl chloride. In some embodiments, the pressure-sensitive adhesive remains adhered to the substrate after being exposed to temperatures ranging from -99°C to -20°C for a period of 1 month to 10 years. In some embodiments, the pressure-sensitive adhesive remains adhered to the substrate after being exposed to temperatures ranging from 20°C to 40°C for a period of 0.5 hours to 24 hours. In some embodiments, the pressure-sensitive adhesive remains adhered to the substrate after being exposed to water for a period of 0.5 hours to 24 hours.

[0012] In some embodiments, the metal chelating agent is triple aluminum, which has the following structure:

[0013]

[0014] In some embodiments, the metal chelating agent is present in an amount ranging from 0.1 wt.% to 5 wt.% based on the total solid weight of the pressure-sensitive adhesive.

[0015] In some embodiments, the glass transition temperature of the polyacrylate-based polymer is in the range of -50°C to -40°C and the molecular weight of the polyacrylate-based polymer is in the range of 350,000 g / mol to 450,000 g / mol, and the glass transition temperature of the polyacrylate tackifier is in the range of -30°C to 50°C and the molecular weight of the polyacrylate tackifier is in the range of 10,000 g / mol to 300,000 g / mol.

[0016] In some embodiments, the polyacrylate-based polymer has a glass transition temperature ranging from -99°C to -20°C and a molecular weight ranging from 200,000 g / mol to 1,500,000 g / mol, wherein the polyacrylate-based polymer is present in an amount ranging from 30 wt.% to 90 wt.% based on the total solid weight of the pressure-sensitive adhesive; wherein the polyacrylate tackifier has a glass transition temperature ranging from -35°C to -50°C and a molecular weight ranging from 10,000 g / mol to 300,000 g / mol, wherein the polyacrylate tackifier is present in an amount ranging from 1 wt.% to 10 wt.% based on the solid weight of the pressure-sensitive adhesive; and wherein the metal chelate crosslinking agent is present in an amount ranging from 0.1 wt.% to 5 wt.%.

[0017] In some embodiments, the glass transition temperature of the polyacrylate-based polymer ranges from -50°C to -40°C, and the molecular weight of the polyacrylate-based polymer ranges from 350,000 g / mol to 450,000 g / mol; wherein the polyacrylate-based polymer is present in an amount ranging from 92 wt.% to 98 wt.% based on the total solid weight of the pressure-sensitive adhesive; wherein the glass transition temperature of the polyacrylate tackifier ranges from -30°C to 50°C, and the molecular weight of the polyacrylate tackifier ranges from 10,000 g / mol to 300,000 g / mol (e.g., 100,000 g). / mol to 200,000 g / mol); wherein the polyacrylate tackifier is present in an amount ranging from 4 wt.% to 10 wt.% based on the solid weight of the pressure-sensitive adhesive; wherein the metal chelating crosslinker is present in an amount ranging from 0.8 wt.% to 1.2 wt.%; and wherein the pressure-sensitive adhesive exhibits a peel strength of at least 11.5 N / inch to 30 N / inch on polyvinyl chloride (as measured by FINAT-1 (2018)) and a static shear strength of 5,000 min to 15,000 min on stainless steel (as measured by FINAT-8 (2018)).

[0018] In some embodiments, the glass transition temperature of the polyacrylate-based polymer ranges from -50°C to -40°C, and the molecular weight of the polyacrylate-based polymer ranges from 350,000 g / mol to 450,000 g / mol; wherein the polyacrylate-based polymer is present in an amount ranging from 92 wt.% to 98 wt.% based on the total solid weight of the pressure-sensitive adhesive; wherein the glass transition temperature of the polyacrylate tackifier ranges from -30°C to 50°C (e.g., -15°C to -8°C) and the molecular weight of the polyacrylate tackifier ranges from 10,000 g / mol to 300,000 g / mol (e.g., 100,000 g / mol to 200,000 g / mol); wherein the polyacrylate tackifier is present in an amount ranging from 4 wt.% to 10 wt.% based on the solid weight of the pressure-sensitive adhesive; The medium metal chelating crosslinking agent is present in an amount ranging from 0.8 wt.% to 1.2 wt.%; wherein the pressure-sensitive adhesive exhibits a peel strength of at least 11.7 N / inch to 30 N / inch on polyvinyl chloride (as measured by FINAT-1 (2018)) and a static shear force greater than 5,000 minutes on stainless steel (as measured by FINAT-8 (2018)); wherein the pressure-sensitive adhesive remains adhered to the substrate when subjected to temperatures ranging from -40°C to 37°C for a period of 0.5 hours to 10 years (e.g., 10 years at -40°C to 0°C); and wherein the pressure-sensitive adhesive remains adhered to the substrate when exposed to water for a period of 0.5 hours to 1 month (e.g., 0.5 hours to 1 week, 0.5 hours to 3 days).

[0019] This disclosure provides a laminate composition comprising a facestock layer and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer comprises any of the pressure-sensitive adhesives disclosed above. In some embodiments, the pressure-sensitive adhesive layer has a thickness ranging from 8 μm to 80 μm.

[0020] In some embodiments, the face layer is a film comprising one or more resins selected from: polyester, polypropylene (PP), PP synthetic paper, polyvinyl chloride (PVC), ABS, polyacrylate, polycarbonate (PC), polyamide, polyimide (PI), polyamidoimide, polyacetal, polyphenylene ether (PPO), polysulfone, polyethersulfone (PES), polyphenylene sulfide, polyetheretherketone (PEEK), polyetherimide (PEI), metallized polyethylene terephthalate (PET), polyvinyl fluoride (PVF), polyethylene ether (PEE), fluorinated ethylene propylene (FEP), polyurethane (PUR), liquid crystal polymer (LCP, aromatic polyesters), polyvinylidene fluoride (PVDF), aramid fiber, dialamy (polymer alloy), polyethylene naphthalate (PEN), ethylene / tetrafluoroethylene (E / TFE), and polyphenylene sulfone (PPSU). In some embodiments, the laminate further comprises a surface coating disposed on top of the face layer.

[0021] Labels containing the aforementioned pressure-sensitive adhesive or the aforementioned laminate composition are also provided.

[0022] A process for producing a pressure-sensitive adhesive is also provided, the process comprising: dissolving a) a polyacrylate-based polymer; b) a polyacrylate tackifier; and c) a metal chelating crosslinking agent in a solvent to form a pressure-sensitive adhesive solution. In some embodiments, the solvent is selected from toluene, ethyl acetate, isopropanol, xylene, n-hexane, n-heptane, methylcyclohexane, butyl acetate, acetone, butanone, and 2-acetoxy-1-methoxypropane. In some embodiments, the method further comprises the steps of coating a face stock with the pressure-sensitive adhesive solution and drying the pressure-sensitive adhesive solution to produce a label.

[0023] In some embodiments, the method further includes applying a label to an article to produce a labeled article, wherein the label remains attached to the article for at least 8 hours after the labeled article has been kept at a temperature in the range of -99°C to 40°C and / or after the label has been in contact with water for at least 0.5 hours.

[0024] A process for applying a pressure-sensitive adhesive to an article is also provided, the process comprising applying a label produced in any of the above processes to the article at an application temperature equal to or below -40°C. In some embodiments, the article is frozen blood product packaging.

[0025] In some embodiments, the glass transition temperature of the polyacrylate-based polymer is lower than the application temperature.

[0026] In some implementations, such as those measured by FINAT test method 1 (2018), the pressure-sensitive adhesive exhibits a peel strength of at least 11.7 N / inch to 30 N / inch on polyvinyl chloride and a static shear force of more than 8000 minutes on stainless steel.

[0027] In some embodiments, the pressure-sensitive adhesive remains attached to the article after being subjected to temperatures ranging from -40°C to 40°C.

[0028] In some implementations, the pressure-sensitive adhesive remains attached to the substrate after a period of contact with water ranging from 0.5 hours to 1 month.

[0029] A pressure-sensitive adhesive solution is also provided, comprising the components and solvent of any pressure-sensitive adhesive as described above. In some embodiments, the polyacrylate-based polymer solution is present in an amount ranging from 30 wt.% to 90 wt.% (e.g., 60 wt.% to 90 wt.%) based on the total weight of the pressure-sensitive adhesive solution. In some embodiments, the solvent is present in an amount ranging from 10 wt.% to 70 wt.% based on the total weight of the pressure-sensitive adhesive solution. Detailed Implementation

[0030] This invention generally relates to pressure-sensitive adhesives (PSAs). The PSAs disclosed herein comprise two different acrylate polymers and a metal chelating agent, and can be used effectively over a wide operating temperature range (e.g., -99°C to 40°C or -40°C to 37°C). As some benefits, these PSAs exhibit optimal tack and cohesion and / or resistance to warm water baths when bonded to a substrate.

[0031] As noted herein, a variety of conventional PSAs are known in the art. However, many of these adhesives do not exhibit the required properties or water resistance for labeling on low-temperature substrates.

[0032] US 8,258,240B2 discloses a PSA comprising two polyacrylate polymers, L and H; however, polymer H has a high glass transition temperature, i.e., in the range between 30°C and 120°C. Therefore, the PSA is not suitable for use at extremely low temperatures.

[0033] US 4,879,178A discloses a PSA comprising a copolymer having a low glass transition temperature in the range of -20°C to -80°C and another copolymer having a high glass transition temperature in the range of 10°C to 40°C. However, the PSA is a thermoplastic PSA, not a solvent-borne PSA. Furthermore, the PSA does not contain a metal chelating crosslinking agent. These differences make this PSA different from the claimed PSA and prevent it from performing well at extremely low temperatures or after exposure to a warm water bath.

[0034] The inventors have discovered that a unique combination of specific components—a particular polyacrylate-based polymer, a polyacrylate tackifier, and a metal chelating crosslinking agent—surprisingly exhibits a synergistic balance of high peel strength and static shear force. Importantly, it has been found that when the glass transition temperature ("T") of the polyacrylate-based polymer and the polyacrylate tackifier is... g With temperatures all below 30°C and the glass transition temperature of the polyacrylate-based polymer being lower than that of the tackifier, PSA exhibits good performance at ultra-low temperatures and / or excellent resistance to warm water baths, which was previously unattainable with existing PSAs.

[0035] Unbound by theory, assuming a lower T g (And optionally higher molecular weight) polyacrylates provide low-temperature adhesion, while higher T... g (And optionally lower molecular weight) polyacrylates can be used as tackifiers and thus provide a surprising increase in tack properties. Importantly, due to the synergistic effect of the components, higher T... g The presence of polyacrylate allows for the use of smaller amounts, providing processing and economic benefits. It also offers the unexpected benefit of reducing or eliminating the need for rosin resin, which has been found to cause problems associated with PSA curing (weakening the ability to adhere to the substrate at extremely low temperatures) and poor warm water bath resistance. Furthermore, it has been found that using the aforementioned higher T... g The polyacrylate also unexpectedly improved the water resistance of PSA without sacrificing other performance properties. It is believed that specific higher T... g Polyacrylates can exhibit a higher degree of cohesion, which contributes to improved water resistance. Furthermore, the use of specific crosslinking agents has been found to significantly increase the polymer's cohesiveness and resistance to warm water baths. Importantly, the use of these specific crosslinking agents also surprisingly has minimal negative impact (if any) on the low-temperature adhesion of PSA. The increased cohesiveness also reduces adhesive overflow issues and facilitates die cutting.

[0036] All scopes and limits referenced in this disclosure include endpoints.

[0037] Polyacrylate polymer

[0038] The PSA disclosed herein comprises two polyacrylate polymers, one of which is more abundant and is referred to herein as the "polyacrylate-based polymer"; the other polyacrylate polymer is present in a smaller amount and can be used as a tackifier and is referred to herein as the "polyacrylate tackifier". In some embodiments, the molecular weight of the polyacrylate-based polymer used herein is typically larger than that of the polyacrylate tackifier. The To of the polyacrylate-based polymer... g It can also be lower than the T of polyacrylate tackifier. g As discussed above, the use of polyacrylate polymers has been found to contribute to the aforementioned benefits. In some embodiments, the T of the polyacrylate-based polymer... g T with polyacrylate tackifier g All are below 30°C, for example, below 20°C, below 10°C, below 0°C, or below -5°C.

[0039] The average molecular weight of polyacrylate-based polymers can vary widely. In some embodiments, the average molecular weight can range from 200,000 g / mol to 1,500,000 g / mol, for example, 200,000 g / mol to 1,000,000 g / mol, 250,000 g / mol to 800,000 g / mol, 300,000 g / mol to 700,000 g / mol, 320,000 g / mol to 500,000 g / mol, 350,000 g / mol to 450,000 g / mol, or about 390,000 g / mol. In terms of the upper limit, the average molecular weight of polyacrylate-based polymers can be less than 1,500,000 g / mol, for example, less than 1,000,000 g / mol, less than 800,000 g / mol, less than 700,000 g / mol, or less than 600,000 g / mol. In terms of the lower limit, the average molecular weight of polyacrylate-based polymers can be greater than 200,000 g / mol, for example, greater than 250,000 g / mol, or greater than 300,000 g / mol.

[0040] In some embodiments, the polyacrylate-based polymer has a T value within a specific range and / or limit. g T g This defines the region in which the polymer transitions from a rigid, glassy material to a soft, elastic material. In some embodiments, the To of the polyacrylate-based polymer... g The range is -99°C to -20°C, for example, -80°C to -30°C, -60°C to -35°C, -50°C to -35°C, -50°C to -40°C, or about -42.5°C. Regarding the lower limit, the T0 of the polyacrylate-based polymer... gAbove -99°C, for example, above -80°C or above -60°C. Regarding the upper limit, the T of polyacrylate-based polymers... g Below -20°C, for example, below -30°C, or below -35°C. The glass transition temperature of polyacrylate-based polymers is typically lower than that of polyacrylate tackifiers. In some embodiments, the Tg of the polyacrylate-based polymer is... g It is 5°C to 50°C lower than polyacrylate tackifiers, for example, 10°C to 45°C lower, 15°C to 40°C lower, 20°C to 35°C lower, or 31°C lower.

[0041] In some embodiments, the PSA comprises a polyacrylate-based polymer in an amount ranging from 30 wt.% to 99.9 wt.% based on the total dry weight of the PSA, for example, 40 wt.% to 99.9 wt.%, 50 wt.% to 99.9 wt.%, 60 wt.% to 90 wt.%, 80 wt.% to 99.9 wt.%, 85 wt.% to 99.9 wt.%, 90 wt.% to 99.8 wt.%, 92 wt.% to 98 wt.%, for example, about 94 wt.%. At the upper limit, the polyacrylate-based polymer is present in an amount less than 100 wt.% and less than 99.9 wt.%. At the lower limit, the polyacrylate-based polymer is present in an amount greater than 30 wt.%, for example, greater than 40 wt.%, greater than 50 wt.%, greater than 60 wt.%, or greater than 70 wt.%.

[0042] Suitable commercially available polyacrylate-based polymers include, but are not limited to, 3-4229, 3422, 3468, and 3462A from Taizhou Yade Adhesive (Zhejiang, China); BPS5296, BPS5330W, and BPS5448 from Toyo Ink (Tokyo, Japan); Etrac 77313 and Etrac 7043 from Eternal (Taiwan, China); Ultra Reclo 109A and Ultra Reclo 236A from Henkel (Düsseldorf, Germany); and Y-1220 and Y-180314X from YASUSA (Jiaxing, China). These polyacrylate-based polymers are typically provided in solution form; for example, 3-4229 has a solids content of approximately 41.5 wt.% and a solvent content of approximately 58.5 wt.%.

[0043] Polyacrylate thickener

[0044] Unlike conventional PSAs that typically use low-molecular-weight tackifiers (e.g., rosin), the PSAs disclosed herein use specific polyacrylates as tackifiers. The inventors have discovered that polyacrylates have a higher molecular weight than rosin, and that using a higher molecular weight tackifier surprisingly imparts increased water resistance to the PSA. This is particularly useful for applications such as PSA-labeled packaging (e.g., blood packaging, which must be thawed in a warm water bath before use). Furthermore, the polyacrylate polymers are structurally closer to the base polymer than rosin; this advantageously allows them to minimize the negative impact of conventional tackifiers on the cohesiveness of the PSA, which is also beneficial for its function when exposed to water.

[0045] The average molecular weight of polyacrylate tackifiers can vary. In some cases, the average molecular weight can range from 10,000 g / mol to 300,000 g / mol, for example, 20,000 g / mol to 280,000 g / mol, 30,000 g / mol to 250,000 g / mol, 90,000 g / mol to 220,000 g / mol, 100,000 g / mol to 200,000 g / mol, or about 190,000 g / mol. At the upper limit, the average molecular weight of polyacrylate-based polymers can be less than 300,000 g / mol, for example, less than 280,000 g / mol or less than 250,000 g / mol. At the lower limit, the average molecular weight of polyacrylate-based polymers can be greater than 10,000 g / mol, for example, greater than 20,000 g / mol, greater than 30,000 g / mol, or greater than 50,000 g / mol.

[0046] T in polyacrylate tackifiers in PSA g Higher than the glass transition temperature of polyacrylate-based polymers. As mentioned above, the inventors have discovered that using a higher T... g The polyacrylate also helps increase the cohesiveness of PSA and thus its water resistance. The T-type polyacrylate thickeners used in PSA... g The typical range is -30°C to 90°C, for example -30°C to 70°C, -20°C to 60°C, -20°C to 50°C, -25°C to -5°C, -20°C to -5°C, and -15°C to -8°C, for example -11°C. Regarding the lower limit, the T... of polyacrylate-based polymers... g Above -30°C, for example above -25°C, or above -15°C. Regarding the upper limit, the T of polyacrylate-based polymers... g Below 90°C, for example, below 70°C, or below 60°C.

[0047] The polyacrylate tackifier is present in the PSA in an amount ranging from 0.5 wt.% to 30 wt.%, for example 1 wt.% to 20 wt.%, 3 wt.% to 15 wt.%, 4 wt.% to 10 wt.%, or for example about 5.6 wt.%, based on the total dry weight of the PSA. At the upper limit, the polyacrylate-based polymer is present in an amount less than 30 wt.%, less than 20 wt.%, or less than 10 wt.%, based on the total solid weight of the PSA. At the lower limit, the polyacrylate-based polymer is present in an amount greater than 0.5 wt.%, for example greater than 1 wt.%, greater than 3 wt.%, or greater than 4 wt.%.

[0048] Exemplary commercially available tackifiers applicable to the PSA disclosed herein include ZHP-108, ZHP-972, ZHP-1143, and 44-127 from DIC (Japan), and from DSM NeoResins. B-804, Aroset TMPS6033, 951001, 95100 from Ashland, STS 0120 from Toyo, Ultra Reclo 247A from Henkel, and BM66, BM24E from Pioneer.

[0049] Various monomers can be used to produce polyacrylate-based polymers or polyacrylate tackifiers, provided that the polymer produced has the desired glass transition temperature as disclosed above. In some embodiments, the polyacrylate-based polymer or polyacrylate tackifier may comprise acrylate monomers, which further comprise alkyl chains. These alkyl chains can vary widely, for example, linear, branched, cyclic, aliphatic, aromatic, saturated, or unsaturated. The number of carbon atoms in the alkyl chains (one or more) of the acrylate monomer can vary, ranging from 1 to 20 carbon atoms, for example, 2 to 15, 2 to 13, 4 to 10, or 4 to 8 carbon atoms. In preferred embodiments, these alkyl chains comprise no more than 20 carbon atoms, for example, no more than 15 carbon atoms, no more than 12 carbon atoms, no more than 8 carbon atoms, no more than 6 carbon atoms, no more than 5 carbon atoms, or no more than 4 carbon atoms. In preferred embodiments, these alkyl chains comprise more than 1 carbon atom, for example, more than 1, more than 3, more than 4, or more than 5 carbon atoms. In some embodiments, the polyacrylate-based polymer or polyacrylate tackifier may comprise a single type of acrylate monomer, while in others, it may comprise a combination of different acrylate monomers. In some embodiments, the polyacrylate-based polymer or polyacrylate tackifier may include acrylic acid (AA), methyl acrylate (MA), butyl acrylate (BA), 2-ethylhexyl acrylate (2-EHA), hydroxyethyl acrylate (HEA), or combinations thereof. In some embodiments, the polyacrylate-based polymer or polyacrylate tackifier does not contain isobutyl methyl acetate (IBMA), ethyl acrylate (EA), vinyl monomers, or combinations thereof.

[0050] Crosslinking agent

[0051] The PSA of the present invention comprises one or more specific crosslinking agents. These one or more crosslinking agents functionally link one polymer chain to another. In some embodiments, one or more crosslinking agents are metal chelating agents. Unlike conventional crosslinking agents, such as aziridine and epoxy resins, metal chelating agents can unexpectedly enhance the ability of the PSA to adhere to a substrate at extremely low temperatures and increase the water resistance of the PSA.

[0052] In some embodiments, the metal chelating crosslinking agent is a metal acetylacetonate, a metal alkoxide, or an alkoxy metal acetylacetonate. The metal acetylacetonate used for the purposes of this invention is a metal chelated with the enol anion of acetylacetone as a ligand. The IUPAC name for acetylacetone is pentane-2,4-dione. The metal alkoxide used for the purposes of this invention is a metal alkoxide, in other words, a compound consisting of a metal cation and an alkoxide anion. Examples of industrially commonly used alkoxides are methanolides, ethanolides, isopropanolides, and tert-butanolides. An alkoxy metal acetylacetonate refers to a complex compound consisting of a metal cation and at least two different ligands, one of which is an alkoxide anion, and the other is the enol anion of acetylacetone. Synonyms for alkoxy metal acetylacetonates are metal alkoxide acetylacetonates or metal acetylacetonate alkoxides. All the metal compounds described may carry additional, further ligands without departing from the concept of this invention. Preferred metals are titanium, aluminum, zirconium, zinc, and iron. In some embodiments, the metal chelating crosslinking agent is a triple aluminum chelating agent. In some embodiments, the metal chelating agent comprises the following structure:

[0053]

[0054] Suitable commercially available metal chelating crosslinking agents include, but are not limited to, ETERAC EC-87 available from Eternal Chemical (China) Ltd., LD-805 available from Yangzhou Lida (China) Ltd., and A-0241 available from TCI (Shanghai) Ltd.

[0055] The PSA may contain 0.1-5 wt.% of a metal chelating crosslinking agent based on the total dry weight of the PSA, for example, 0.1 to 5 wt.%, 0.2 wt.% to 4 wt.%, 0.3 wt.% to 3 wt.%, 0.5 wt.% to 2 wt.%, 0.6 wt.% to 1.5 wt.%, 0.8 wt.% to 1.2 wt.%, or about 1 wt.%. At the upper limit, the PSA contains less than 5 wt.%, less than 4 wt.%, less than 3 wt.%, less than 2 wt.%, and less than 1.5 wt.% of epoxy resin based on the total dry weight of the PSA. At the lower limit, the PSA contains more than 0.1 wt.%, more than 0.2 wt.%, more than 0.3 wt.%, more than 0.5 wt.%, more than 0.6 wt.%, and more than 0.8 wt.% of epoxy resin based on the total dry weight of the PSA.

[0056] In some embodiments, the PSA contains less than 2 wt.%, such as less than 1 wt.%, less than 0.5 wt.%, less than 0.3 wt.%, or less than 0.1 wt.%, of rosin resin, aziridine, or epoxy resin or combinations thereof. As described above, reducing the amount of rosin resin in the PSA reduces / eliminates problems associated with the hardening of the PSA (which weakens its ability to adhere to the substrate at extremely low temperatures) and poor resistance to warm water baths.

[0057] As described above, the unique combination of polyacrylate-based polymers, polyacrylate tackifiers, and / or metal chelate crosslinking agents provides surprising results, namely that PSA can remain adhered to the substrate at ultra-low temperatures (-40°C or lower) and / or when PSA is in contact with water (e.g., immersed in a water bath with a temperature range of 30°C to 40°C, such as 37°C).

[0058] In certain specific cases, the glass transition temperature of the polyacrylate-based polymer can range from -50°C to -40°C, and the molecular weight of the polyacrylate-based polymer can range from 350,000 g / mol to 450,000 g / mol. The polyacrylate-based polymer can be present in an amount ranging from 92 wt.% to 98 wt.% based on the total solid weight of the pressure-sensitive adhesive.

[0059] In another embodiment, the glass transition temperature of the polyacrylate tackifier is in the range of -30°C to 50°C, and the molecular weight of the polyacrylate tackifier is in the range of 10,000 g / mol to 300,000 g / mol (e.g., 100,000 g / mol to 300,000 g / mol); and the polyacrylate tackifier may be present in an amount ranging from 4 wt.% to 10 wt.% based on the solid weight of the pressure-sensitive adhesive; the metal chelate crosslinking agent may be present in an amount ranging from 0.8 wt.% to 1.2 wt.%.

[0060] PSA containing the above-mentioned components exhibits optimal adhesion and shear strength. In some embodiments, PSA exhibits a peel strength of at least 11.7 N / inch to 30 N / inch on PVC (measured according to FINAT-1 (2018) after 20 minutes of PSA being attached to the PVC sheet) and a static shear strength of 5,000 minutes to 15,000 minutes on stainless steel (measured by FINAT-8 (2018) at ambient temperature).

[0061] When the pressure-sensitive adhesive has been exposed to water for a period of time from 0.5 hours to 1 day (e.g., 0.5 hours to 10 hours, 0.5 hours to 6 hours), the PSA is able to maintain its adhesion to the substrate.

[0062] In some embodiments, the PSA has several characteristics that, when combined, contribute to excellent low-temperature performance and water resistance: the glass transition temperature of the polyacrylate-based polymer ranges from -99°C to -20°C; the molecular weight of the polyacrylate-based polymer ranges from 200,000 g / mol to 1,500,000 g / mol (e.g., 200,000 g / mol to 1,000,000 g / mol); the polyacrylate-based polymer is present in an amount ranging from 70 wt.% to 99.9 wt.% based on the total solid weight of the pressure-sensitive adhesive; the glass transition temperature of the polyacrylate tackifier ranges from -35°C to -50°C; the molecular weight of the polyacrylate tackifier ranges from 10,000 g / mol to 300,000 g / mol; the polyacrylate tackifier is present in an amount ranging from 1 wt.% to 10 wt.% based on the solid weight of the pressure-sensitive adhesive; and the metal chelate crosslinking agent is present in an amount ranging from 0.1 wt.% to 5 wt.%.

[0063] In some embodiments, the glass transition temperature of the polyacrylate-based polymer ranges from -50°C to -40°C; the molecular weight of the polyacrylate-based polymer ranges from 350,000 g / mol to 450,000 g / mol; the polyacrylate-based polymer is present in an amount ranging from 92 wt.% to 98 wt.% based on the total solid weight of the pressure-sensitive adhesive; the glass transition temperature of the polyacrylate tackifier ranges from -15°C to -8°C, and the molecular weight of the polyacrylate tackifier ranges from 100,000 g / mol to 200,000 g / mol. The polyacrylate tackifier is present in an amount ranging from 4 wt.% to 10 wt.% based on the solid weight of the pressure-sensitive adhesive; the metal chelating crosslinker is present in an amount ranging from 0.8 wt.% to 1.2 wt.%; and the pressure-sensitive adhesive exhibits a peel strength of at least 11.7 N / inch to 30 N / inch on polyvinyl chloride (as measured by FINAT-1 (2018)) and a static shear force of greater than 5,000 minutes (e.g., greater than 8,000 minutes) on stainless steel (as measured by FINAT-8 (2018)).

[0064] In some embodiments, the glass transition temperature of the polyacrylate-based polymer ranges from -50°C to -40°C; the molecular weight of the polyacrylate-based polymer ranges from 350,000 g / mol to 450,000 g / mol; the polyacrylate-based polymer is present in an amount ranging from 92 wt.% to 98 wt.% based on the total solid weight of the pressure-sensitive adhesive; the glass transition temperature of the polyacrylate tackifier ranges from -15°C to -8°C; the molecular weight of the polyacrylate tackifier ranges from 10,000 g / mol to 300,000 g / mol (e.g., 100,000 g / mol to 200,000 g / mol); and the polyacrylate tackifier is present in an amount ranging from 4 wt.% to 4 wt.% based on the total solid weight of the pressure-sensitive adhesive. The adhesive is present in amounts ranging from wt.% to 10 wt.%; the metal chelating crosslinker is present in amounts ranging from 0.8 wt.% to 1.2 wt.%; and the pressure-sensitive adhesive exhibits a peel strength of at least 11.7 N / inch to 30 N / inch on polyvinyl chloride (as measured by FINAT-1 (2018)) and a static shear force greater than 5,000 minutes on stainless steel (as measured by FINAT-8 (2018)); the pressure-sensitive adhesive remains adhered to the substrate when it has been exposed to temperatures ranging from -40°C to 37°C for a period of time from 0.5 hours to 10 years; and the pressure-sensitive adhesive remains adhered to the substrate when it has been exposed to water for a period of time from 0.5 hours to 1 week.

[0065] Laminate composition

[0066] This disclosure also provides a laminate composition comprising any of the PSAs disclosed above. The laminate composition may include a facestock layer and an adhesive layer comprising the PSAs disclosed herein. In some cases, the laminate composition further includes a topcoat layer disposed on top of the facestock layer. In some cases, the laminate composition further includes one or more primer layers and / or liners, as further described below. This disclosure also contemplates labels comprising the laminate composition.

[0067] Surface layer

[0068] The laminate composition may have one or more face layers. In one embodiment, from a downward view of the substrate, the face layer is located on the top surface of the label, exposed to the environment, and configured to receive printable information, such as barcodes or alphanumeric characters.

[0069] In some embodiments, the pressure-sensitive adhesive is provided in the form of a planarization layer (optionally as a layer in the laminate composition). The thickness of the planarization layer ranges from 8 to 80 μm, for example 12 to 50 μm, 10 to 60 μm, 20 to 70 μm, 30 to 60 μm, or 20 to 50 μm, or other ranges of the above amounts. At the lower limit, the thickness of the PSA layer may be at least 8 μm, for example at least 10 μm, at least 20 μm, or at least 30 μm. At the upper limit, the thickness of the polyolefin film may be less than 80 μm, for example less than 70 μm, less than 60 μm, or less than 50 μm.

[0070] The face layer may include, for example, cellophane, kraft paper, and polyesters (such as polyethylene terephthalate (PET), polyamide (PA), polyethylene naphthalate (PEN)), cotton, tissue paper, paper, fiberglass, synthetic textiles, and polyolefins (such as polypropylene (PP), polyvinyl chloride (PVC), ethylene-propylene copolymer, polyethylene (PE)) and combinations thereof. Other polymeric film materials include urethane-based polymers, such as polyether urethane and polyester urethane; amide-based polymers, including polyether polyamide copolymers; acrylic-based polymers, including polyacrylate and ethylene / vinyl acetate copolymers; polyester-based polymers, including polyether polyester; vinyl chloride; vinylidene chloride; polystyrene; polyacrylonitrile; polycarbonate; polyimide; ABS; polyacrylate; polycarbonate (PC); polyamide; polyimide (PI); polyamide-imide; polyacetal; polyphenylene ether (PPO); polysulfone, polyethersulfone (PES); polyphenylene sulfide; Polyether ether ketone (PEEK); polyetherimide (PEl); metallized polyethylene terephthalate (PET); polyvinyl fluoride (PVF); polyethylene ether (PEE); fluorinated ethylene propylene (FEP); polyurethane (PUR); liquid crystal polymer (LCP, aromatic polyester); polyvinylidene fluoride (PVDF); aramid fiber; DIALAMY (polymer alloy); polyethylene naphthalate (PEN); ethylene / tetrafluoroethylene (E / TFE); polyphenylene sulfone (PPSU); and polymers or polymer alloys comprising one or more of these materials.

[0071] The thickness or coating amount of the faceplate layer can vary depending on the label hardness desired for a particular application. According to certain embodiments of the invention, the faceplate layer may include a thickness ranging from 100 μm to 1,000 μm, for example, 200 μm to 800 μm, 150 μm to 500 μm, 300 μm to 600 μm, 450 μm to 900 μm, or other ranges of the foregoing amounts. At the lower limit, the thickness of the faceplate layer may be at least 100 μm, for example, at least 150 μm, at least 200 μm, or at least 300 μm. At the upper limit, the thickness of the polyolefin film may be less than 1000 μm, for example, less than 800 μm, less than 500 μm, less than 400 μm, or less than 300 μm. In some embodiments, the faceplate layer is 125 μm.

[0072] In some embodiments, the laminate composition includes a topcoat layer disposed on top of the face stock layer. The topcoat layer can enhance printability, durability, and / or chemical resistance. In one embodiment, the label's topcoat layer typically comprises a resin. Non-limiting examples of resins suitable for use as topcoats include polyester amino resins and phenoxy resins, polyester isocyanates, polyurethanes, and polyacrylates. In some embodiments, the topcoat layer may have one or more additional properties, such as UV resistance and scratch resistance.

[0073] In some embodiments, the topcoat layer can also be configured to accept printing. For example, the topcoat layer may include one or more printable layers containing an ink-receptive composition for forming printable information. Many such compositions are known in the art, and these compositions typically include a binder and a pigment, such as silica or talc, dispersed in the binder. Optionally, the printable layer contains a crosslinking agent CX-100 (a multifunctional aziridine liquid crosslinking agent for DSM). Several such ink-receptive compositions are described in U.S. Patent No. 6,153,288, the disclosure of which is incorporated herein by reference. Printable information can be deposited on the topcoat layer using various printing techniques, such as screen printing, dot matrix printing, inkjet printing, laser printing, laser marking, thermal transfer, etc. In some cases, the topcoat layer can accept thermal transfer printing.

[0074] Inks used for printing on topcoats can vary considerably and can include commercially available water-based, solvent-based, or radiation-cured inks. Examples of such inks include Sun Sheen (a product of Sun Chemical, classified as an alcohol-dilutable polyamide ink). MP (a product of Sun Chemical, recognized as a solvent-based ink for surface printing on acrylic coated substrates, PVDC coated substrates and polyolefin films), X-Cel (a product of Water Ink Technologies, recognized as a water-based film ink for printing on film substrates), Uvilith AR-109 Rubine Red (a product of Daw Ink, recognized as a UV ink), and CLA91598F (a product of Sun Chemical, recognized as a multi-bonded black solvent-based ink).

[0075] In some cases, the printable layer can be a layer that utilizes activatable inks, such as stimulus-activatable inks, like laser-activated, pressure-activated, or temperature-activated inks.

[0076] According to certain embodiments of the present invention, the topcoat layer can be applied to the surface portion of the surface material layer using any technique known in the art (such as spraying, roller coating, brushing, or other techniques). A printable layer can be formed on the topcoat layer by deposition, gravure printing, or other methods, wherein the bottom surface is in contact with the top surface of the topcoat layer.

[0077] Other (optional) components

[0078] In some cases, the PSA, topcoat layer, topcoat layer, or primer layer may optionally include one or more fillers, antioxidants, UV absorbers, light stabilizers, and / or fillers. These additives can be incorporated into the binder in conventional amounts using conventional equipment and techniques. For example, representative fillers may include talc, calcium carbonate, organoclay, glass fiber, marble dust, cement dust, feldspar, silica or glass, fumed silica, silicates, alumina, various phosphorus compounds, ammonium bromide, titanium dioxide, antimony trioxide, zinc oxide, zinc borate, barium sulfate, silicone, aluminum silicate, calcium silicate, glass microspheres, chalk, mica, clay, wollastonite, ammonium octamolate, and expanded compounds or mixtures of two or more of these materials. Fillers may also carry or contain various coatings or treatment agents, such as silanes, fatty acids, etc. Other fillers may include flame retardants, such as halogenated organic compounds. In some embodiments, the topcoat may include one or more thermoplastic elastomers compatible with other components of the layer, such as etherified melamine, hydroxylated polyester, polyester-melamine, and other suitable elastomers.

[0079] Optionally, the label disclosed herein includes one or more primer layers, and the one or more primer layers may be located between the topcoat layer and the adhesive layer.

[0080] liner

[0081] In some embodiments, the label further includes a backing pad deposited on the opposite side of the surface of the reactive adhesive layer that contacts the faceplate layer. The releasable backing pad may be positioned adjacent to the reactive adhesive layer such that the reactive adhesive layer is directly or indirectly disposed or sandwiched between the bottom surface of the faceplate layer and the releasable backing pad. The releasable backing pad may act as a protective shield, holding the releasable backing pad in place until the label is ready to be attached to an object. If the label includes a backing pad or a releasable backing pad, the backing pad can use a variety of materials and constructions. In many embodiments, the backing pad is paper or a paper-based material. In many other embodiments, the backing pad is a polymer film of one or more polymeric materials. Typically, at least one side of the backing pad is coated with a release material, such as silicone or a silicone-based material. As will be understood, the release material-coated side of the backing pad is positioned to contact the otherwise exposed side of the adhesive layer. Before applying the label to the surface of interest, the backing pad is removed to thereby expose the adhesive side of the label. The backing pad may be in the form of a single sheet. Alternatively, the backing pad may be in the form of multiple sections or sheets.

[0082] The thickness of the padding used in the label can range from 20 μm to 150 μm, for example, 30 μm to 120 μm, 60 μm to 100 μm, or 50 μm to 90 μm. At the upper limit, the label thickness is less than 150 μm, for example, less than 130 μm or less than 100 μm. At the lower limit, the label thickness is greater than 20 μm, for example, greater than 30 μm or greater than 40 μm.

[0083] Various additives can also be added to one or more topcoat layers, primer layers, adhesive layers, or backing layers to obtain certain desired properties. These additives may include, for example, one or more waxes, surfactants, talc, powdered silicates, fillers, defoamers, colorants, antioxidants, UV stabilizers, luminescents, crosslinking agents, buffers, anti-caking agents, wetting agents, matting agents, antistatic agents, acid removers, flame retardants, processing aids, extrusion aids, etc.

[0084] performance

[0085] The PSA disclosed herein exhibits good mechanical properties, such as high peel strength, indicating excellent adhesion. Peel strength is the average force required to remove an adhesive laminated onto a substrate under specific conditions from the substrate at a constant speed and a specific angle. Peel strength can be evaluated using methods known in the art. In some embodiments, peel strength is evaluated according to FINAT Test Method 1 (2018) (“FINAT-1”). Samples containing the PSA to be tested are prepared by cutting strips to suitable test dimensions. For example, the strips may have a width of 50 mm and a length of 175 mm. Backing material (if present) is removed before the strips are adhered to a clean test plate using rollers. Typically, at least three strips of each sample are tested 20 minutes after the PSA has been adhered to the plate or 48 hours after the PSA has been adhered. In some embodiments, the test plate is positioned relative to the measuring device at a peel angle of 180°. The test plate can be any material suitable for evaluating the peel strength of the PSA. In some embodiments, the test plate comprises polyvinyl chloride. The peel force is recorded as the strip is peeled from the test plate at a predetermined speed (e.g., 300 mm per minute). Typically, at least five readings are recorded from the center of each strip at 10mm intervals.

[0086] In some cases, when PSA has been attached to a PVC test plate for 20 minutes, according to FINAT-1 (2018), PSA may exhibit a peel strength of 11.7 N / inch to 40 N / inch, for example 12 N / inch to 35 N / inch, 13 N / inch to 30 N / inch, 13.5 N / inch to 20 N / inch, for example, approximately 11.5 N / inch. At the upper limit, PSA exhibits a peel strength of less than 40 N / inch, less than 35 N / inch, less than 30 N / inch, or less than 20 N / inch on a stainless steel substrate. At the lower limit, PSA exhibits a peel strength greater than 11.7 N / inch, greater than 12 N / inch, greater than 13 N / inch, or greater than 13.5 N / inch.

[0087] The PSA disclosed also exhibits high static shear force, indicating excellent cohesion. Static shear force can be tested using methods known in the art. A test sample containing the PSA is centered on a test plate, and pressure is applied to the test sample containing the PSA to cover an area on the test plate, for example, a 12.5 mm × 12.5 mm area. The test plate can be made of any material suitable for static shear force testing. In one embodiment, the test plate is a stainless steel plate. Typically, the test sample is adhered to the steel plate at ambient temperature for one day before a 0.5 kg load is applied. The weight of the load gradually pulls the sample off the test plate. The duration the sample remains on the test plate can be recorded. The longer the sample remains on the plate, the greater the static shear force exhibited by the sample.

[0088] In some cases, when tested on stainless steel at ambient temperature, the static shear force exhibited by PSA ranges from 5,000 minutes to 15,000 minutes, for example, 6,000 minutes to 12,000 minutes, 7,000 minutes to 10,000 minutes, or 7,500 minutes to 8,500 minutes, or approximately 8,000 minutes. The lower limit is greater than 5,000 minutes, greater than 6,000 minutes, greater than 7,000 minutes, or greater than 8,000 minutes. The upper limit is less than 15,000 minutes, less than 12,000 minutes, or less than 10,000 minutes. In some cases, the use of polyacrylate tackifiers instead of non-polyacrylate tackifiers can increase cohesion, as reflected by the fact that the static shear force of PSAs with polyacrylate tackifiers, as measured using FINAT-8 (2018), is at least 2, at least 5, at least 10, and at least 100 times higher than that of PSAs with non-polyacrylate tackifiers.

[0089] As described above, and without limitation by any particular theory, it is believed that using polyacrylate polymers as tackifiers in PSA can significantly increase the viscosity and cohesiveness of PSA. In some cases, the molecular weight of the polyacrylate tackifier is much higher than that of conventional tackifiers. Polyacrylate tackifiers themselves can also be used as adhesives, therefore using acrylates as tackifiers can minimize the negative impact on the cohesiveness of PSA and increase the static shear strength and water resistance of PSA. In some embodiments, as shown in Example 1, when the other components of PSA are the same, using a polyacrylate tackifier instead of a non-polyacrylate tackifier (such as rosin) can increase viscosity by 10% to 60%. In some embodiments, the increase in viscosity is between 15% and 50%, for example between 20% and 40%, or about 27%. At the upper limit, the increase is less than 60%, for example less than 50%, or less than 40%. At the lower limit, the increase is greater than 10%, greater than 15%, or greater than 20%.

[0090] In some embodiments, the pressure-sensitive adhesive of the present invention, having a unique combination of a polyacrylate-based polymer, a polyacrylate tackifier, and / or the aforementioned metal chelating crosslinking agent, can remain adhered to the substrate after the PSA has been in contact with water for 0.5 hours to 1 week, for example, 0.5 hours to 24 hours, 1 hour to 10 hours, or for example, about 6 hours. In some embodiments, the water temperature is 30°C to 40°C, for example, about 37°C. In some embodiments, the PSA can remain adhered to the substrate at temperatures of -40°C or lower. In some embodiments, the PSA can remain adhered to the substrate when it has been subjected to temperatures ranging from -99°C to -20°C, for example, -90°C to -20°C, or -80°C to -40°C.

[0091] adhesive solution

[0092] This disclosure also provides an adhesive solution comprising the solvent disclosed above, a polyacrylate-based polymer (typically in solution form, such as polyacrylate-based polymer 3-4229 which may contain 41.5 wt.% solids), a polyacrylate tackifier (also typically in solution form, such as polyacrylate tackifier 247A which may contain 48 wt.% solids), and a metal chelating crosslinking agent. The glass transition temperature of the polyacrylate-based polymer is lower than that of the polyacrylate tackifier. Both the glass transition temperatures of the polyacrylate tackifier and the polyacrylate-based polymer are below 90°C.

[0093] Solvents that can be used to produce the PSA disclosed herein may be one or more solvents selected from the following: toluene, ethyl acetate, isopropanol, xylene, n-hexane, n-heptane, methylcyclohexane, butyl acetate, acetone, butanone, and 2-acetoxy-1-methoxypropane.

[0094] In some embodiments, the polyacrylate-based polymer solution contains 25 wt.% to 60 wt.%, for example, 30 wt.% to 60 wt.%, 35 wt.% to 50 wt.%, 40 wt.% to 50 wt.%, 40 wt.% to 55 wt.%, or about 41.5 wt.% of polyacrylate-based polymer solids. At the upper limit, the polyacrylate-based polymer solution contains less than 60 wt.%, less than 55 wt.%, less than 50 wt.%, or less than 45 wt.% of polyacrylate-based polymer solids. At the lower limit, the polyacrylate-based polymer solution contains more than 30 wt.%, for example, more than 35 wt.%, or more than 40 wt.% of polyacrylate-based polymer solids. In some embodiments, the polyacrylate-based polymer solution is present in the PSA solution in an amount ranging from 60 wt.% to 90 wt.%, for example, 65 wt.% to 85 wt.%, 70 wt.% to 90 wt.%, 75 wt.% to 85 wt.%, or about 80 wt.%, based on the total weight of the pressure-sensitive adhesive solution. At the upper limit, the PSA solution comprises less than 90 wt.% and less than 85 wt.% of the polyacrylate-based polymer solution based on the total weight of the PSA solution. At the lower limit, the PSA solution comprises more than 70 wt.%, for example, more than 75 wt.%, of the polyacrylate-based polymer solution based on the total weight of the PSA solution. In some embodiments, the polyacrylate-based polymer solution is 3-4229, which contains 41.5 wt.% solids (Taizhou Yade Adhesive Co., Ltd., Taizhou, China).

[0095] In some embodiments, the polyacrylate tackifier solution comprises 30 wt.% to 60 wt.%, for example 40 wt.% to 55 wt.%, or about 48 wt.%, of solids content. The polyacrylate tackifier solution may be present in an amount ranging from 1 wt.% to 10 wt.%, for example 1 wt.% to 9 wt.%, 3 wt.% to 8 wt.%, for example, about 3.7 wt.%, based on the total weight of the pressure-sensitive adhesive solution. At the upper limit, the PSA solution comprises less than 10 wt.%, less than 9 wt.%, and less than 8 wt.%, of polyacrylate tackifier solution based on the total weight of the PSA solution. At the lower limit, the PSA solution comprises more than 1 wt.%, for example more than 2 wt.%, of polyacrylate tackifier solution based on the total weight of the PSA solution. In some embodiments, the polyacrylate tackifier solution is 247A from Henkel (Düsseldorf, Germany), which comprises 48 wt.%, of solids content.

[0096] The amount of one or more solvents used in the production of the adhesive solution can vary depending on the desired viscosity suitable for coating onto a substrate or other layer. Typically, the solvent is present in the adhesive solution in an amount ranging from 10 wt.% to 70 wt.%, for example, 10 wt.% to 40 wt.%, 8 wt.% to 30 wt.%, 10 wt.% to 25 wt.%, 12 wt.% to 20 wt.%, for example, about 15.6 wt.%. At the lower limit, the solvent is present in an amount greater than 5 wt.% based on the total weight of the adhesive solution, for example, greater than 8 wt.%, greater than 10 wt.%, or greater than 12 wt.%, or greater than 15 wt.%. At the upper limit, the solvent is present in an amount less than 70 wt.%, less than 60 wt.%, less than 40 wt.%, less than 30 wt.%, or less than 25 wt.% based on the total weight of the adhesive solution.

[0097] PSA production

[0098] This invention also relates to a method for producing PSA. The method includes dissolving a polyacrylate-based polymer, a polyacrylate tackifier, and a metal chelating crosslinking agent in a solvent to form an adhesive solution. Any of the above-described embodiments of the polyacrylate-based polymer, polyacrylate tackifier, and metal chelating crosslinking agent can be used to produce the adhesive solution. Exemplary PSA solutions are prepared using the components shown in Table 1. This process is commonly referred to as compounding. Compounding can occur at temperatures below 50°C, for example, between 20°C and 40°C, or between 20°C and 30°C.

[0099] A variety of solvents can be used to dissolve the components of PSA. Suitable solvents include those that exhibit appropriate evaporation rates and in which the various components exhibit good solubility. In a preferred embodiment, the solvent is a petroleum-based solvent. Suitable solvents include, but are not limited to, aromatic solvents, aliphatic solvents, ester solvents, xylene, ethylbenzene, isopropanol, and combinations thereof. Examples of aromatic solvents include aromatic rings having alkyl substitutions (e.g., toluene). Examples of ester solvents include esters with three or more carbon atoms (e.g., methyl acetate or ethyl acetate). In some embodiments, two or more solvents can be used to dissolve the various components described above to produce an adhesive solution.

[0100] The adhesive solution prepared as described above exhibits good coatability, with typical viscosities ranging from 100 to 5,000 cps, such as 200 to 4,000 cps, 300 to 3,000 cps, 400 to 2,000 cps, 300 to 600 cps, or approximately 500 cps. At the lower limit, viscosities are greater than 100, such as greater than 200 cps, greater than 300 cps, or greater than 400 cps. At the upper limit, viscosities are less than 5,000, less than 4,000 cps, less than 2,000 cps, and less than 1,000 cps. Methods for measuring viscosity are well-known, such as the Brookfield viscometer method, which tests the flow resistance of a fluid by rotating it at low and medium speeds.

[0101] The adhesive solution can be applied to the surface material using methods known for solvent-based adhesives, for example, as disclosed in Manufacturing Pressure-Sensitive Adhesive Products: A Coating and Laminating Process, which is available at adhesivesmag.com / articles / 86079-manufacturing-pressure-sensitive-adhesive-products-a-coating-and-laminating-process, the contents of which are incorporated herein by reference in their entirety.

[0102] In some embodiments, coating is performed by direct coating, wherein the pressure-sensitive adhesive is applied directly to the face stock or backing material and dried to produce a label. In some embodiments, coating is performed by transfer coating, wherein the adhesive is first applied to a release liner (as described above) and dried. The dried adhesive / liner is then laminated to the face stock.

[0103] In some embodiments, the adhesive solution produced above can then be applied to the face stock or release liner using a solvent coater via a roller-lined scraper, slit die, or comma scraper. The solution can be coated to form an adhesive layer with a coating weight of at least 5 grams per square meter (gsm), for example, at least 10 gsm or at least 15 gsm. Up to the maximum, the solution can be coated to form an adhesive layer with a coating weight of 60 gsm or less, for example, 50 gsm or less, or 40 gsm or less. In a range, the solution can be coated to form an adhesive layer with a coating weight of 5 gsm to 60 gsm, for example, 10 gsm to 50 gsm or 15 gsm to 40 gsm, depending on the end use of the adhesive layer. The face stock / liner coated with the above solution can then be dried and processed into a label as further described below. In some cases, it is used as a transfer adhesive unrelated to the face stock.

[0104] The coating process is typically carried out in an oven with multiple temperature zones, such as at least two, three, four, five, or six zones. The temperature zones can range from 30°C to 200°C, for example, 40°C to 150°C or 60°C to 130°C. The temperature may increase from the first zone to the last, but multiple zones may be at the same temperature.

[0105] Once applied, the adhesive can be dried in an oven for a predetermined drying time. The temperature of the drying oven can be above 100°C. The solvent evaporation rate increases with temperature. The drying time can be at least 2 minutes, at least 4 minutes, at least 6 minutes, at least 8 minutes, at least 10 minutes, at least 15 minutes, at least 20 minutes, at least 25 minutes, at least 30 minutes, at least 40 minutes, at least 50 minutes, or at least 1 hour.

[0106] Labeling products

[0107] The present invention also relates to a method of applying a label containing PSA to an article (also referred to as a substrate). The present invention also provides labeled articles. These methods include, according to embodiments, providing an article and a label defining an outer surface. These methods further include affixing the label to the outer surface of the article, thereby applying the label to the article.

[0108] Labels can be applied to articles in batches, continuously, or semi-continuously. Before application, one or more backings can be removed from the label to expose the adhesive side. The adhesive side and label are then brought into contact with the container(s) or article(s) and the label is applied to the container or article. Adhesion may also include one or more operations such as pressing or otherwise applying pressure to the label to facilitate contact and / or adhesion to the container; activating and / or curing the adhesive, such as by heating and / or exposure to ultraviolet light; and / or drying operations.

[0109] In some embodiments, the article to be labeled is an article having a temperature of -40°C or lower. In some embodiments, the article is one that, after being labeled with the PSA of the present invention, is placed in a warm water bath at a temperature of 30°C to 40°C, for example, about 37°C. In some embodiments, the article is a blood package. In some embodiments, the label is affixed to a surface, for example, that of a blood package. In some embodiments, the label is attached to tubing attached to a blood product package.

[0110] Adhesive system

[0111] Typically, during storage, the solution containing the polyacrylate-based polymer, and optionally a polyacrylate tackifier, is kept separate from the metal chelating crosslinking agent to prevent undesirable crosslinking. The crosslinking agent can be added to the solution containing the polyacrylate-based polymer immediately before the production of the adhesive and / or label. Therefore, an adhesive system is also provided comprising: a) a polyacrylate-based polymer; b) a metal crosslinking agent; the crosslinking agent being separate from the polyacrylate-based polymer.

[0112] The materials in the adhesive system may be present in an amount such that the produced PSA has the properties described in this disclosure.

[0113] Implementation

[0114] The present invention is further illustrated by the following exemplary embodiments.

[0115] Implementation Method 1: Pressure-sensitive adhesive, comprising: a polyacrylate-based polymer having a certain glass transition temperature, a polyacrylate tackifier having a certain glass transition temperature, and a metal chelating crosslinking agent, wherein the glass transition temperatures of the polyacrylate tackifier and the polyacrylate-based polymer are both below 90°C, and wherein the glass transition temperature of the polyacrylate-based polymer is lower than the glass transition temperature of the polyacrylate tackifier.

[0116] Implementation Method 2: The pressure-sensitive adhesive of Implementation Method 1, wherein the adhesive is a solvent-based PSA.

[0117] Embodiment 3: The pressure-sensitive adhesive of Embodiment 1, wherein the glass transition temperature of the polyacrylate-based polymer is in the range of -99°C to -20°C.

[0118] Embodiment 4: The pressure-sensitive adhesive of any one of Embodiments 1-2, wherein the glass transition temperature of the polyacrylate tackifier is greater than -30°C.

[0119] Embodiment 5: A pressure-sensitive adhesive according to any one of Embodiments 1-2, wherein the glass transition temperature range of the polyacrylate tackifier is -30°C to 90°C.

[0120] Embodiment 6: The pressure-sensitive adhesive of any one of Embodiments 1-5, wherein the glass transition temperature of the polyacrylate-based polymer is in the range of -50°C to -35°C.

[0121] Embodiment 7: The pressure-sensitive adhesive of any one of Embodiments 1-6, wherein the T of the polyacrylate-based polymer... g T compared to polyacrylate tackifiers g Temperatures can range from 5°C to 100°C.

[0122] Embodiment 8: A pressure-sensitive adhesive of any one of Embodiments 1-7, wherein the molecular weight of the polyacrylate-based polymer is greater than the molecular weight of the polyacrylate tackifier.

[0123] Embodiment 9: A pressure-sensitive adhesive of any one of Embodiments 1-8, wherein the molecular weight of the polyacrylate-based polymer ranges from 200,000 g / mol to 1,500,000 g / mol.

[0124] Embodiment 10: A pressure-sensitive adhesive of any one of Embodiments 1-9, wherein the polyacrylate-based polymer is present in an amount ranging from 30 wt.% to 99.9 wt.% based on the total solid weight of the pressure-sensitive adhesive.

[0125] Embodiment 11: A pressure-sensitive adhesive of any one of Embodiments 1-10, wherein the polyacrylate-based polymer is selected from one or more polymers selected from Taizhou Yade Adhesive's 3-4229, 3422, 3468 and 3462A; Toyo Ink's BPS5296, BPS5330W and BPS5448; Eternal's Etrac 77313 and Etrac 7043; Henkel's Ultra Reclo 109A and Ultra Reclo 236A; and YASUSA's Y-1220 and Y-180314X.

[0126] Embodiment 12: A pressure-sensitive adhesive of any one of Embodiments 1-11, wherein the molecular weight of the polyacrylate tackifier ranges from 10,000 g / mol to 300,000 g / mol.

[0127] Embodiment 13: A pressure-sensitive adhesive of any one of Embodiments 1-12, wherein the polyacrylate tackifier is present in an amount ranging from 0.5 wt.% to 30 wt.% based on the total solid weight of the pressure-sensitive adhesive.

[0128] Embodiment 14: A pressure-sensitive adhesive of any one of Embodiments 1-13, wherein the polyacrylate-based polymer contains less than 2 wt.% rosin resin, aziridine, or epoxy resin or a combination thereof.

[0129] Example 15: A pressure-sensitive adhesive of any one of Examples 1-14, wherein the pressure-sensitive adhesive exhibits a peel strength greater than 11.6 N / inch on polyvinyl chloride, as measured by FINAT test method 1 (2018).

[0130] Embodiment 16: A pressure-sensitive adhesive of any one of Embodiments 1-15, wherein, according to FINAT 2018, the pressure-sensitive adhesive exhibits a shear force greater than 8,000 minutes on stainless steel.

[0131] Embodiment 17: A pressure-sensitive adhesive of any one of Embodiments 1-16, wherein the pressure-sensitive adhesive has a peel strength on polyvinyl chloride ranging from 5 N / inch to 20 N / inch.

[0132] Embodiment 18: The pressure-sensitive adhesive of any one of Embodiments 1-17, wherein the pressure-sensitive adhesive can remain adhered to the substrate when it has been subjected to a temperature range of -99°C to -20°C for a period of time from 1 month to 10 years.

[0133] Embodiment 19: The pressure-sensitive adhesive of any one of Embodiments 1-17, wherein the pressure-sensitive adhesive can remain attached to the substrate when it has been subjected to a temperature range of 20°C to 40°C for a period of time from 1 month to 10 years.

[0134] Embodiment 20: A pressure-sensitive adhesive according to any one of Embodiments 1-18, wherein the pressure-sensitive adhesive remains adhered to the substrate when it has been in contact with water for a period of 0.5 hours to 1 month. Optionally, the water temperature is 37°C.

[0135] Embodiment 21: A pressure-sensitive adhesive of any one of Embodiments 1-20, wherein the metal chelating agent is a triple aluminum having the following structure:

[0136]

[0137] Embodiment 22: A pressure-sensitive adhesive of any one of Embodiments 1-21, wherein the metal chelating agent is present in an amount ranging from 0.1 wt.% to 5 wt.% based on the total solid weight of the pressure-sensitive adhesive.

[0138] Embodiment 23: A pressure-sensitive adhesive of any one of Embodiments 1-22, wherein the glass transition temperature of the polyacrylate-based polymer is in the range of -50°C to -40°C, and the molecular weight of the polyacrylate-based polymer is in the range of 350,000 g / mol to 450,000 g / mol, and wherein the glass transition temperature of the polyacrylate tackifier is in the range of -30°C to 50°C, and the molecular weight of the polyacrylate tackifier is in the range of 10,000 g / mol to 300,000 g / mol (e.g., 100,000 g / mol to 200,000 g / mol).

[0139] Embodiment 24: A pressure-sensitive adhesive according to any one of Embodiments 1-22, wherein the glass transition temperature of the polyacrylate-based polymer is in the range of -99°C to -20°C, and the molecular weight of the polyacrylate-based polymer is in the range of 200,000 g / mol to 1,500,000 g / mol.

[0140] The polyacrylate-based polymer is present in an amount ranging from 70 wt.% to 80 wt.% based on the total solid weight of the pressure-sensitive adhesive;

[0141] The glass transition temperature of the polyacrylate tackifier ranges from -35°C to -50°C, and the molecular weight of the polyacrylate tackifier ranges from 10,000 g / mol to 300,000 g / mol.

[0142] The polyacrylate tackifier is present in an amount ranging from 1 wt.% to 10 wt.% based on the solid weight of the pressure-sensitive adhesive; and

[0143] The metal chelating crosslinking agent is present in an amount of 0.1 wt.% to 5 wt.%.

[0144] Implementation Method 25: The pressure-sensitive adhesive of any one of Implementation Methods 1-24,

[0145] The glass transition temperature of the polyacrylate-based polymer ranges from -50°C to -40°C, and the molecular weight of the polyacrylate-based polymer ranges from 350,000 g / mol to 450,000 g / mol.

[0146] The polyacrylate-based polymer is present in an amount ranging from 92 wt.% to 98 wt.% based on the total solid weight of the pressure-sensitive adhesive;

[0147] The glass transition temperature of the polyacrylate tackifier ranges from -30°C to 50°C, and the molecular weight of the polyacrylate tackifier ranges from 100,000 g / mol to 200,000 g / mol.

[0148] The polyacrylate tackifier is present in an amount ranging from 4 wt.% to 10 wt.% based on the solid weight of the pressure-sensitive adhesive;

[0149] The metal chelating crosslinking agent is present in an amount ranging from 0.8 wt.% to 1.2 wt.%; and

[0150] Among them, as measured by FINAT-1 (2018), the pressure-sensitive adhesive exhibits a peel strength of at least 11.7 N / inch to 30 N / inch on polyvinyl chloride, and a static shear force of 5,000 minutes to 15,000 minutes on stainless steel, as measured by FINAT-8 (2018).

[0151] Implementation Method 26: The pressure-sensitive adhesive of any one of Implementation Methods 1-25,

[0152] The glass transition temperature of the polyacrylate-based polymer ranges from -50°C to -40°C, and the molecular weight of the polyacrylate-based polymer ranges from 350,000 g / mol to 450,000 g / mol.

[0153] The polyacrylate-based polymer is present in an amount ranging from 92 wt.% to 98 wt.% based on the total solid weight of the pressure-sensitive adhesive;

[0154] The glass transition temperature of the polyacrylate tackifier ranges from -15°C to -8°C, and the molecular weight of the polyacrylate tackifier ranges from 100,000 g / mol to 200,000 g / mol.

[0155] The polyacrylate tackifier is present in an amount ranging from 4 wt.% to 10 wt.% based on the solid weight of the pressure-sensitive adhesive;

[0156] The metal chelating crosslinking agent is present in an amount of 0.8 wt.% to 1.2 wt.%.

[0157] Among them, as measured by FINAT-1 (2018), the pressure-sensitive adhesive exhibits a peel strength of at least 11.7 N / inch to 30 N / inch on polyvinyl chloride, and as measured by FINAT-8 (2018), it exhibits a static shear force of more than 5000 minutes on stainless steel.

[0158] The pressure-sensitive adhesive can maintain its adhesion to the substrate even after being exposed to temperatures ranging from -40°C to 37°C for a period of 0.5 hours to 10 years; and

[0159] When the pressure-sensitive adhesive has been in contact with water for a period of 0.5 hours to 1 week, it can maintain its adhesion to the substrate.

[0160] Embodiment 27: A laminate composition comprising a face material layer and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer comprises any one of the pressure-sensitive adhesives of Embodiments 1-26.

[0161] Example 28: The laminate composition of Example 27, wherein the thickness of the pressure-sensitive adhesive layer ranges from 8 μm to 80 μm.

[0162] Example 29: The laminate composition of Example 27, wherein the face layer is a film comprising one or more resins selected from: polyester, polypropylene (PP), PP synthetic paper, polyvinyl chloride (PVC), ABS, polyacrylate, polycarbonate (PC), polyamide, polyimide (PI), polyamide-imide, polyacetal, polyphenylene ether (PPO), polysulfone, polyethersulfone (PES), polyphenylene sulfide, polyether ether ketone (PEEK), polyetherimide (PEl), metallized polyethylene terephthalate (PET), polyvinyl fluoride (PVF), polyethylene ether (PEE), fluorinated ethylene propylene (FEP), polyurethane (PUR), liquid crystal polymer (LCP, aromatic polyester), polyvinylidene fluoride (PVDF), aramid fiber, DIALAMY (polymer alloy), polyethylene naphthalate (PEN), ethylene / tetrafluoroethylene (E / TFE), and polyphenylene sulfone (PPSU).

[0163] Embodiment 30: A laminate composition of any one of Embodiments 27-29, wherein the laminate further comprises a surface coating disposed on top of the face material layer.

[0164] Embodiment 31: A label comprising any one of the pressure-sensitive adhesives of Embodiments 1-26 or the laminate compositions of Embodiments 27-30.

[0165] Implementation Method 32: A process for producing pressure-sensitive adhesives, the process comprising: dissolving a) a polyacrylate-based polymer; b) a polyacrylate tackifier; and c) a metal chelating crosslinking agent in a solvent to form a pressure-sensitive adhesive solution.

[0166] Implementation Method 33: The process of Implementation Method 32, wherein the solvent is selected from toluene, ethyl acetate, isopropanol, xylene, n-hexane, n-heptane, methylcyclohexane, butyl acetate, acetone, butanone, and 2-acetoxy-1-methoxypropane.

[0167] Implementation method 34: The process of any one of implementation methods 32-33, wherein the method further includes the steps of: coating a face material with a pressure-sensitive adhesive solution, and drying the pressure-sensitive adhesive solution to produce a label.

[0168] Implementation 35: The process of any one of Implementations 32-33, wherein the method further comprises the following steps: coating a release liner with a pressure-sensitive adhesive solution, drying the pressure-sensitive adhesive solution on the release liner to produce a dried PSA / liner composition, and applying the dried PSA / liner composition to a face stock to produce a label.

[0169] Implementation 36: The process of any one of Implementations 34-35, wherein the method further includes applying a label to an article to produce a labeled article, wherein the label is able to remain attached to the article after the labeled article has been subjected to a temperature in the range of -99°C to 40°C for at least 6 hours and / or after the label has been in contact with water for at least 5 hours.

[0170] Embodiment 37: A process for applying a pressure-sensitive adhesive to an article, the process comprising: applying a label produced by the process of Embodiment 34 or 35 to the article at an application temperature equal to or below -40°C.

[0171] Implementation method 38: The process of implementation method 36 or 37, wherein the product is a frozen blood product package.

[0172] Implementation Method 39: The process of any one of Implementation Methods 36-38, wherein the glass transition temperature of the polyacrylate-based polymer is lower than the application temperature.

[0173] Implementation 40: The process of any one of Implementations 36-39, wherein the pressure-sensitive adhesive exhibits a peel strength of at least 11.7 N / inch to 30 N / inch on polyvinyl chloride and a static shear force of more than 8,000 minutes on stainless steel, as measured by FINAT test method 1 (2018).

[0174] Embodiment 41: The process of any of Embodiments 36-40, wherein the pressure-sensitive adhesive remains attached to the article after being subjected to a temperature ranging from -40°C to 40°C.

[0175] Implementation method 42: The process of any one of implementation methods 37-41, wherein the pressure-sensitive adhesive remains attached to the article after a period of contact with water of 0.5 hours to 1 month.

[0176] Embodiment 43: The pressure-sensitive adhesive solution comprises the pressure-sensitive adhesive and solvent of any one of Embodiments 1-26.

[0177] Example 44: The pressure-sensitive adhesive solution of Example 41, wherein the polyacrylate-based polymer solution is present in an amount ranging from 60 wt.% to 90 wt.% based on the total weight of the pressure-sensitive adhesive solution.

[0178] Embodiment 45: Pressure-sensitive adhesive solution of Embodiments 43-44, wherein the solvent is present in an amount ranging from 10 wt.% to 70 wt.% based on the total weight of the pressure-sensitive adhesive solution.

[0179] Example

[0180] The following embodiments are provided to illustrate, but do not limit, the claimed invention.

[0181] Procedure I: The Role of Polyacrylate Tackifiers

[0182] Three exemplary PSA solutions with the components listed in Table 2 were prepared. The values ​​in Table 2 represent the weight percentage of each individual component based on the total weight of the PSA solution. The numbers in parentheses in the first column represent the percentage of solids in each component, which can be used to calculate the solid weight percentage of the component based on the solid weight of the PSA.

[0183] Table 1 lists the sources and characteristics of the individual components.

[0184]

[0185]

[0186] Each PSA solution is applied to the pad and dried. After drying, the pad / PSA is laminated with the face stock to form a laminate comprising the pad, PSA and face stock, wherein one surface of the PSA is coated on the pad and the opposite surface is coated on the face stock (i.e., a laminate of pad / PSA adhesive / face stock).

[0187] The peel strength and static shear force of the PSA-containing laminate, its ability to adhere to blood packaging at ultra-low temperatures, and the resistance of PSA to warm water baths were tested according to the following methods.

[0188] To test peel strength, the PSA-containing laminate was cut into strips 50 mm wide × 175 mm long. The release liner was peeled off the strips. The strips were then bonded to a test plate using a 2 kg roller in a single back-and-forth motion. After 20 minutes of adhesion, the peel strength (N / 25 mm width) was measured at ambient temperature and 50% relative humidity according to the FINAT-1 test protocol. Measurements were obtained using a tensile strength tester at a pull speed of 300 mm / min and a pull angle of 180°. At least five peel force readings were recorded at 10 mm intervals from the center of each strip. The average of the five readings was reported as the peel strength of the PSA.

[0189] Examples of static shear force are evaluated as follows.

[0190] Clean a 50mm wide and 75mm long painted stainless steel sheet, ensuring it is free of stains, discoloration, or scratches. Carefully avoid touching the sheet surface with your fingers throughout the procedure. Adhere the sample to the test sheet using a 2kg roller in a single back-and-forth motion. The test sample containing PSA should be placed in the center of the test sheet. Apply the sample without increasing pressure to cover a 12.5mm long and 12.5mm wide area on the test sheet. Place the sample on the steel sheet at ambient temperature for one day before applying a 0.5kg load. Maintain a relative humidity of 50% during the test. Record the duration of the sample on the steel sheet for each specimen.

[0191] The PSA-containing laminate was cut into strips 12.5 mm wide × 60 mm long. The release liner was peeled off the strips and then bonded to the center of a clean stainless steel test plate (75 mm long and 50 mm wide) using a 2 kg roller in a single back-and-forth motion. The coverage area on the stainless steel plate was 12.5 mm long and 12.5 mm wide. After 20 minutes of adhesion, the shear strength was measured at ambient temperature and 50% relative humidity according to the FINAT-1 test protocol. The duration of the sample on the steel plate was recorded for each specimen.

[0192] Tolerance to a warm water bath was determined by immersing labeled blood packages in a 37°C water bath for 6 hours. At the end of the 30-minute period, the blood packages were removed from the water bath and their labels were inspected. If the labels did not detach or peel off, the PSA was determined to be resistant to a warm water bath (or performed well when exposed to a warm water bath) and was given a "pass" rating.

[0193] The ability to apply labels at extremely low temperatures was tested on blood packages that had been stored at -40°C for at least one day. In one set of experiments, the blood package was removed, the frozen surface was wiped off, and then a label containing PSA was applied to the surface of the blood package. In another set of experiments, the blood package was removed, the surface was not wiped off, and the label containing PSA was applied directly to the surface of the blood package. In either set of experiments, if the label did not detach or move relative to the blood package, the label was given a "pass" status.

[0194] The peel strength and shear force results were obtained from tests conducted according to FINAT-1 (2018) and FINAT-8 (2018), respectively. "Pass" for labeling blood packaging at -40°C means that the label did not peel or slip off the packaging during labeling. "Pass" for a 37°C water bath means that the label on the blood bag did not detach or peel off, and the label on the tubing attached to the blood packaging did not stretch out or detach.

[0195] The results (see Table 2) indicate that the product contains 247A, BM-66, and BM-66 with polyacrylate tackifiers. The PSAs in Examples 1-3, using B-804 as a tackifier, exhibited excellent performance in labeling substrates at ultra-low temperatures (e.g., -40°C or lower) and in a 37°C water bath. 247A, BM-66, and... B-804 are all polyacrylate tackifiers with glass transition temperatures of -11°C, 50°C, and 33°C, respectively. After 20 minutes of adhesion to a PVC test plate, PSA exhibited an additional 11.5 N / inch peel strength on PVC and greater than 8000 minutes of shear force on stainless steel at ambient temperature. For the water bath test, the comparative examples showed lower peel values ​​and a "fail". This indicates that the presence of polyacrylate as a tackifier in PSA significantly increases tackiness and cohesion when PSA is used at extremely low temperatures or in contact with water. These advantageous properties allow the use of PSA in labeled articles (e.g., blood packaging) for use at extremely low temperatures and in warm water baths, under conditions where conventional PSA typically does not provide satisfactory results.

[0196] The role of metal chelating crosslinking agents in Program II

[0197] Two additional comparative examples, Comparative Example C and Comparative Example D, were prepared from the components listed in Table 3 as described in Procedure II. The values ​​in Table 3 represent the weight percentage of each individual component based on the total weight of the PSA solution. The numbers in brackets in the first column represent the solids content of each component. Each PSA solution was coated onto a liner and allowed to dry. After drying, the liner was peeled off, and the dried PSA was transferred to the face stock to form a laminate. The peel strength and static shear force of the PSA-containing laminate, its ability to adhere to blood packaging at cryogenic temperatures, and the PSA's resistance to warm water baths were tested as described above. The results are shown in Table 3.

[0198]

[0199] The results showed that Example 1, containing the metal chelating crosslinking agent ETERAC EC-87 (triple aluminum chelator), exhibited excellent performance when used for labeling substrate surfaces at ultra-low temperatures (e.g., -40°C or lower) or when immersed in a 37°C water bath. Furthermore, the PSA of Example 1 could be directly adhered to packaging at -40°C without prior wiping of the packaging surface. In contrast, Comparative Examples C and D, containing epoxy resin GY240 (Jiadida NewMaterial, Shenzhen, China) and aziridine XR-2500 from Stahl Holdings BV (Waalwijk, the Netherlands) as crosslinking agents for the PSA, respectively, failed to maintain adhesion to the blood packaging after immersion in a 37°C water bath. Unlike Comparative Examples C and D, which exhibited peel strengths of 8.2 N / inch and 8.6 N / inch, respectively, Example 1 showed a much higher peel strength of 11.5 N / inch on PVC after 20 minutes of adhesion. The label additionally exhibited a static shear force of over 8000 minutes on stainless steel, significantly higher than comparative examples C and D, which showed 159 CP (label detached from stainless steel plate after 159 minutes) and 111 CP (label detached from stainless steel plate after 111 minutes), respectively. "CP" stands for "clear panel." This indicates that the use of a metal chelating agent as a crosslinking agent in the PSA significantly increases viscosity and cohesion, resulting in excellent performance of the PSA when subjected to low temperatures or warm water baths.

[0200] This invention has been described in detail, and modifications within the spirit and scope of the invention will be readily apparent to those skilled in the art. In view of the foregoing discussion, all relevant knowledge and references in the art discussed above in conjunction with the background and specific embodiments are incorporated herein by reference. Furthermore, it should be understood that various aspects of the invention, as well as portions of the various embodiments and features listed above and / or in the appended claims, can be combined or interchanged in whole or in part. In the foregoing description of various embodiments, those embodiments relating to another embodiment may be suitable for combination with other embodiments, as understood by those skilled in the art. Moreover, those skilled in the art will understand that the foregoing description is merely illustrative and not intended to limit the invention.

Claims

1. A pressure-sensitive adhesive, comprising: Polyacrylate-based polymers with a certain glass transition temperature. Polyacrylate tackifiers with a certain glass transition temperature, and Metal chelating crosslinking agents, The glass transition temperature of both the polyacrylate tackifier and the polyacrylate-based polymer is below 90°C. The glass transition temperature of the polyacrylate-based polymer is 5°C to 100°C lower than that of the polyacrylate tackifier.

2. The pressure-sensitive adhesive of claim 1, wherein the adhesive is a solvent-based PSA.

3. The pressure-sensitive adhesive of claim 1, wherein the glass transition temperature of the polyacrylate-based polymer is in the range of -99°C to -20°C.

4. The pressure-sensitive adhesive according to any one of claims 1-2, wherein the glass transition temperature of the polyacrylate tackifier is greater than -30°C.

5. The pressure-sensitive adhesive according to any one of claims 1-2, wherein the glass transition temperature of the polyacrylate tackifier is in the range of -30°C to 90°C.

6. The pressure-sensitive adhesive according to any one of claims 1-3, wherein the glass transition temperature of the polyacrylate-based polymer is in the range of -50°C to -35°C.

7. The pressure-sensitive adhesive according to any one of claims 1-3, wherein the molecular weight of the polyacrylate-based polymer is greater than the molecular weight of the polyacrylate tackifier.

8. The pressure-sensitive adhesive according to any one of claims 1-3, wherein the polyacrylate-based polymer has a molecular weight range of 200,000 g / mol to 1,500,000 g / mol.

9. The pressure-sensitive adhesive of any one of claims 1-3, wherein the polyacrylate-based polymer is present in an amount ranging from 30 wt.% to 99.9 wt.% based on the total solid weight of the pressure-sensitive adhesive.

10. The pressure-sensitive adhesive according to any one of claims 1-3, wherein the polyacrylate-based polymer and / or the polyacrylate tackifier comprises acrylic acid (AA), methyl acrylate (MA), butyl acrylate (BA), 2-ethylhexyl acrylate (2-EHA), hydroxyethyl acrylate (HEA), or a combination thereof.

11. The pressure-sensitive adhesive according to any one of claims 1-3, wherein the polyacrylate tackifier has a molecular weight range of 10,000 g / mol to 300,000 g / mol.

12. The pressure-sensitive adhesive of any one of claims 1-3, wherein the polyacrylate tackifier is present in an amount ranging from 0.5 wt.% to 30 wt.% based on the total solid weight of the pressure-sensitive adhesive.

13. The pressure-sensitive adhesive of any one of claims 1-3, wherein the polyacrylate-based polymer comprises less than 2 wt.% rosin resin, aziridine, or epoxy resin or a combination thereof.

14. The pressure-sensitive adhesive of any one of claims 1-3, wherein the pressure-sensitive adhesive exhibits a peel strength greater than 11.5 N / inch on polyvinyl chloride as measured according to FINAT test method 1 (2018).

15. The pressure-sensitive adhesive according to any one of claims 1-3, wherein, according to FINAT 2018, the pressure-sensitive adhesive exhibits a shear force greater than 5,000 minutes on stainless steel.

16. The pressure-sensitive adhesive of any one of claims 1-3, wherein the pressure-sensitive adhesive has a peel strength on polyvinyl chloride ranging from 5 N / inch to 20 N / inch.

17. The pressure-sensitive adhesive according to any one of claims 1-3, wherein the pressure-sensitive adhesive remains adhered to the substrate when it has been subjected to a temperature range of -99°C to -20°C for a period of one month to ten years.

18. The pressure-sensitive adhesive according to any one of claims 1-3, wherein the pressure-sensitive adhesive remains adhered to the substrate when it has been subjected to a temperature ranging from 20°C to 40°C for a period of one month to ten years.

19. The pressure-sensitive adhesive according to any one of claims 1-3, wherein the pressure-sensitive adhesive remains adhered to the substrate when it has been in contact with water for a period of 0.5 hours to 24 hours.

20. The pressure-sensitive adhesive according to any one of claims 1-3, wherein the metal chelating crosslinking agent is a triple aluminum having the following structure: 。 21. The pressure-sensitive adhesive according to any one of claims 1-3, wherein the metal chelating crosslinking agent is present in an amount ranging from 0.1 wt.% to 5 wt.% based on the total solid weight of the pressure-sensitive adhesive.

22. The pressure-sensitive adhesive of any one of claims 1-3, wherein the glass transition temperature of the polyacrylate-based polymer is in the range of -50°C to -40°C, and the molecular weight of the polyacrylate-based polymer is in the range of 350,000 g / mol to 450,000 g / mol, and wherein the glass transition temperature of the polyacrylate tackifier is in the range of -30°C to 50°C, and the molecular weight of the polyacrylate tackifier is in the range of 100,000 g / mol to 200,000 g / mol.

23. The pressure-sensitive adhesive according to any one of claims 1-3, wherein the glass transition temperature of the polyacrylate-based polymer is in the range of -99°C to -20°C, and the molecular weight of the polyacrylate-based polymer is in the range of 200,000 g / mol to 1,500,000 g / mol. The polyacrylate-based polymer is present in an amount ranging from 70 wt.% to 80 wt.% based on the total solid weight of the pressure-sensitive adhesive; The glass transition temperature of the polyacrylate tackifier is in the range of -35°C to -50°C, and the molecular weight of the polyacrylate tackifier is in the range of 10,000 g / mol to 300,000 g / mol. The polyacrylate tackifier is present in an amount ranging from 1 wt.% to 10 wt.% based on the solid weight of the pressure-sensitive adhesive; and The metal chelating crosslinking agent is present in an amount of 0.1 wt.% to 5 wt.%.

24. The pressure-sensitive adhesive according to any one of claims 1-3, The glass transition temperature of the polyacrylate-based polymer is in the range of -50°C to -40°C, and the molecular weight of the polyacrylate-based polymer is in the range of 350,000 g / mol to 1,500,000 g / mol. The polyacrylate-based polymer is present in an amount ranging from 80 wt.% to 99.9 wt.% based on the total solid weight of the pressure-sensitive adhesive; The glass transition temperature of the polyacrylate tackifier is in the range of -30°C to 50°C, and the molecular weight of the polyacrylate tackifier is in the range of 10,000 g / mol to 300,000 g / mol. The polyacrylate tackifier is present in an amount ranging from 0.5 wt.% to 10 wt.% based on the solid weight of the pressure-sensitive adhesive; The metal chelating crosslinking agent is present in an amount ranging from 0.8 wt.% to 1.2 wt.%; and The pressure-sensitive adhesive exhibits a peel strength of at least 11.5 N / inch to 30 N / inch on polyvinyl chloride, as measured by FINAT-1 (2018), and a static shear force of more than 5000 minutes on stainless steel, as measured by FINAT-8 (2018).

25. The pressure-sensitive adhesive according to any one of claims 1-3, The glass transition temperature of the polyacrylate-based polymer is in the range of -50°C to -40°C, and the molecular weight of the polyacrylate-based polymer is in the range of 350,000 g / mol to 450,000 g / mol. The polyacrylate-based polymer is present in an amount ranging from 85 wt.% to 98 wt.% based on the total solid weight of the pressure-sensitive adhesive; The glass transition temperature of the polyacrylate tackifier is in the range of -30°C to 50°C, and the molecular weight of the polyacrylate tackifier is in the range of 10,000 g / mol to 300,000 g / mol. The polyacrylate tackifier is present in an amount ranging from 0.5 wt.% to 10 wt.% based on the solid weight of the pressure-sensitive adhesive; The metal chelating crosslinking agent is present in an amount ranging from 0.8 wt.% to 1.2 wt.%; and The pressure-sensitive adhesive exhibits a peel strength of 11.7 N / inch to 30 N / inch on polyvinyl chloride, as measured by FINAT-1 (2018), and a static shear force of more than 5000 minutes on stainless steel, as measured by FINAT-8 (2018). The pressure-sensitive adhesive remains adhered to the substrate even after being subjected to temperatures ranging from -40°C to 37°C for 0.5 hours to 10 years. The pressure-sensitive adhesive can remain attached to the substrate when it has been in contact with water for 0.5 hours to 1 month.

26. A laminate composition comprising a face material layer and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer comprises any one of claims 1-25.

27. The laminate composition of claim 26, wherein the thickness of the pressure-sensitive adhesive layer ranges from 8 μm to 80 μm.

28. The laminate composition of claim 26, wherein the face layer is a film comprising one or more resins selected from: polyester, polypropylene (PP), PP synthetic paper, ABS, polyvinyl chloride (PVC), polyacrylate, polycarbonate (PC), polyamide, polyimide (PI), polyamide-imide, polyacetal, polyphenylene ether (PPO), polysulfone, polyethersulfone (PES), polyphenylene sulfide, polyetheretherketone (PEEK), polyetherimide (PEI), metallized polyethylene terephthalate (PET), polyvinyl fluoride (PVF), polyethylene ether (PEE), fluorinated ethylene propylene (FEP), polyurethane (PUR), aromatic polyester liquid crystal polymers, polyvinylidene fluoride (PVDF), aramid fiber, dialamy, polyethylene naphthalate (PEN), ethylene / tetrafluoroethylene (E / TFE), polyphenylene sulfone (PPSU).

29. The laminate composition of any one of claims 26-28, wherein the laminate further comprises a surface coating disposed on top of the surface layer.

30. A label comprising any one of the pressure-sensitive adhesives of claims 1-25 or the laminate compositions of claims 26-29.

31. A process for producing pressure-sensitive adhesives, the process comprising: Will a) Polyacrylate-based polymers with a certain glass transition temperature; b) Polyacrylate tackifiers with a certain glass transition temperature; and c) Metal chelating crosslinking agents; Dissolved in a solvent to form a pressure-sensitive adhesive solution. The glass transition temperature of both the polyacrylate tackifier and the polyacrylate-based polymer is below 90°C. The glass transition temperature of the polyacrylate-based polymer is 5°C to 100°C lower than that of the polyacrylate tackifier.

32. The process of claim 31, wherein the solvent is selected from toluene, ethyl acetate, isopropanol, xylene, n-hexane, n-heptane, methylcyclohexane, butyl acetate, acetone, butanone, and 2-acetoxy-1-methoxypropane.

33. The process according to any one of claims 31-32, The process further includes the following steps: The pressure-sensitive adhesive solution is applied to the surface material, and the pressure-sensitive adhesive solution is dried to produce a label; or The process further includes the following steps: coating the release liner with the pressure-sensitive adhesive solution, drying the pressure-sensitive adhesive solution on the release liner to produce a dried PSA / liner composition, and applying the dried PSA / liner composition to the face stock to produce a label.

34. The process of claim 33, wherein the process further comprises applying the label to an article to produce a labeled article, wherein the label remains attached to the article after the labeled article has been held at a temperature in the range of -99°C to 40°C for at least 8 hours, and / or the label remains attached to the article after the label has been in contact with water for at least 0.5 hours.

35. A process for applying a pressure-sensitive adhesive to an article, the process comprising: The label produced by the process of claim 33 is applied to the article at an application temperature equal to or below -40°C.

36. The process of claim 35, wherein the article is a frozen blood product package.

37. The process of any one of claims 35-36, wherein the glass transition temperature of the polyacrylate-based polymer is lower than the application temperature.

38. The process of any one of claims 35-36, wherein the pressure-sensitive adhesive exhibits a peel strength of at least 11.5 N / inch to 30 N / inch on polyvinyl chloride and a static shear force of more than 8000 minutes on stainless steel, as measured by FINAT test method 1 (2018).

39. The process of any one of claims 35-36, wherein the pressure-sensitive adhesive remains attached to the article after being subjected to a temperature ranging from -40°C to 40°C.

40. The process of any one of claims 35-36, wherein the pressure-sensitive adhesive remains applied to the article after a period of contact with water of 0.5 hours to 1 month.

41. Pressure-sensitive adhesive solution, including The components of the pressure-sensitive adhesive according to any one of claims 1-25, and Solvent.

42. The pressure-sensitive adhesive solution of claim 41, wherein the polyacrylate-based polymer solution is present in an amount ranging from 30 wt.% to 90 wt.% based on the total weight of the pressure-sensitive adhesive solution.

43. The pressure-sensitive adhesive solution of any one of claims 41-42, wherein the solvent is present in an amount ranging from 10 wt.% to 70 wt.% based on the total weight of the pressure-sensitive adhesive.

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