Silicone-free and fluorine-free release coatings comprising

Abstract

Provided herein is a release coating composition comprising at least one polymeric binder and one or more microbeads wherein the amount of microbeads is in the range of from 1 vol% to 85 vol% of the total dry volume of the release coating composition. The release coating composition is suitable for recovery and printing, and can be used in linerless self-winding label laminate constructions.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese Patent Application No. 202211246883.5 filed on October 12, 2022 and U.S. Provisional Patent Application No. 63 / 380,296 filed on October 20, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present subject matter generally relates to release coating compositions. The present subject matter specifically relates to a silicone-free, fluorine-free release coating composition. The present subject matter also relates to a release coating composition suitable for recycling and printing, and can be used in a self-wrap label lamination construction involving no liner. Background Art

[0004] In general, release coating compositions are applied to surfaces such as paper, plastics and other films to produce non-stick surfaces or to achieve the installation of viscous materials (such as adhesive coatings) by providing a protective cover. When the adhesive layer is intended to be exposed to adhere to a given substrate, the non-stick surface provided by these coatings allows adhesives and other viscous materials to be easily peeled off and separated. In addition, release coatings are mainly used to make the backing materials of label laminates, adhesive tapes, decals and graphic structures, but their purposes are extended to any application that needs to avoid unintentional adhesion. In pressure-sensitive labels, adhesive tapes, decals and graphic applications, release coatings allow pressure-sensitive adhesives to easily break away from the backing material without affecting the performance of the adhesive. The materials commonly used for release coatings are organosilicon compounds, fluorinated or partially fluorinated compounds, polymer-based compositions and wax compositions. Silicone-containing release coatings are widely used in industry with their excellent release properties.

[0005] Despite their excellent performance, silicone-containing release coatings are costly due to the use of expensive raw materials. In addition, silicone coatings require dedicated coating lines and additional processing steps during the manufacturing process. In addition, silicone release coatings also lead to contamination of the adhesive layer after lamination of the adhesive onto the release coating due to the diffusion of silicone residues, which adversely affects the adhesive performance. The residual silicone left over during the separation process can cause various problems during the disintegration or recycling of the liner carrying the silicone. As a result, a large amount of label backings produced each year are sent to landfills and complicate recycling or reduce their reuse rate.

[0006] Non-silicone strippers are also used in the process of manufacturing precision electronic devices such as hard disk drives, ceramic capacitors, semiconductor devices, etc. Non-silicone strippers prevent silicone deposits from contaminating electronic components, thereby reducing potential defects in electronic devices. However, none of the non-silicone strippers used can replicate the properties required of a strong release coating to improve its shortcomings.

[0007] Release coatings based on fluorinated chemicals, fluorinated or partially fluorinated compounds are also expensive. In addition, these fluorinated chemical-based coatings are usually provided in solvent form, and these chemical compositions have potential environmental risks. Release coatings based on polymers such as polypropylene, polyethylene, polyester, polyurethane, various copolymers and combinations thereof are also used. However, many of these materials have higher peeling forces than many peeling performance requirements. In addition, since silicone, fluorinated chemicals, polymers or combinations thereof and wax-based release coatings inherently have low surface energies, none of them can be printed. Therefore, these coating surfaces are difficult to be wetted by ink, or even if printed, the ink adhesion is also poor, resulting in poor print quality.

[0008] In view of the challenges identified above, there remains a need for alternative release coatings that are environmentally friendly, have good adhesion coating properties, are recyclable, have high print quality, and have excellent and stable release properties. Summary of the invention

[0009] In one aspect of the present invention, a peel-coat composition is provided. More specifically, the peel-coat composition described herein relates to a silicone-free, fluorine-free peel-coat composition. Advantageously, the peel-coat composition is recyclable and can be printed using any suitable method.

[0010] The silicone-free and fluorine-free peel coating composition comprises at least one polymer binder and one or more microbeads, wherein the amount of the microbeads is in the range of 1 vol% to 85 vol% of the total dry volume of the peel coating composition. In some embodiments, the ratio (v / v) of the amount of the microbeads to the amount of the polymer binder is in the range of 1:0.1 to 1:60.

[0011] In some embodiments, the polymer base includes at least one polymer selected from the group consisting of polyvinyl pyrrolidone, polyurethane, polyacrylate, sulfonated polyester, modified polyolefin, polyvinyl alcohol, and combinations thereof.

[0012] In other embodiments, the polymer base includes a first polymer and a second polymer, wherein the first polymer is polyvinyl pyrrolidone, and the second polymer is at least one polymer selected from the group consisting of polyurethane, polyacrylate, sulfonated polyester, modified polyolefin, polyvinyl alcohol, and combinations thereof. The ratio (wt / wt) of the amount of the first polymer to the amount of the second polymer in the polymer base is in the range of 95:5 to 5:95.

[0013] According to an embodiment of the present invention, the microbeads include one of glass beads, glass bubbles, alumina particles, aluminum hydroxide particles and polymer beads, the polymer beads including but not limited to poly(methyl methacrylate) beads, polystyrene beads or poly(butyl methacrylate) beads, and the average particle size is in the range of 5μm to 100μm.

[0014] In some embodiments, the silicone-free, fluorine-free release coating composition further comprises at least one additive selected from the group consisting of a deformation agent, a rheology modifier, a dispersant, a pH modifier, an antimicrobial agent, an antistatic agent, and a crosslinking agent.

[0015] In another aspect of the present invention, a release liner is provided, comprising a substrate having a first side and a second side; and a release coating composition coated on at least one of the first side and the second side of the substrate, wherein the release coating composition comprises at least one polymer binder and one or more microbeads, wherein the amount of the microbeads ranges from 1 vol% to 85 vol% of the total dry volume of the release coating composition.

[0016] In still another aspect of the present invention, a laminate is provided comprising a face material having a first side and a second side; a pressure sensitive adhesive disposed on the first side of the face material; optionally, a release liner coated on at least one of the adhesives disposed on the face material and a release coating composition coated on the second side of the face material or at least one of the adhesive-covered sides of the release liner, wherein the release coating composition is silicone-free and fluorine-free and comprises at least one polymeric binder and one or more microbeads, wherein the amount of the microbeads is in the range of 1 vol% to 85 vol% of the total dry volume of the release coating composition.

[0017] In some embodiments, the laminate comprises a face stock having a first side and a second side; a pressure-sensitive adhesive disposed on the first side of the face stock; a release liner at least partially covering the adhesive disposed on the face stock; and a release coating composition coated on the adhesive-covered side of the release liner. In other embodiments, the laminate comprises a face stock having a first side and a second side; a pressure-sensitive adhesive disposed on the first side of the face stock; and a release coating composition coated on the second side of the face stock.

[0018] Other features and advantages of the present invention will become apparent to those skilled in the art through the following detailed description. However, it should be understood that, while indicating preferred and other embodiments of the present invention, detailed descriptions of various embodiments and specific examples are given by way of illustration rather than limitation. Many changes and modifications within the scope of the present invention may be made without departing from the spirit of the present invention, and the present invention includes all of these modifications. DETAILED DESCRIPTION

[0019] Various embodiments and features or advantageous details are described with reference to the non-limiting embodiments shown or described in the specification. Descriptions of known components and processing techniques are omitted to avoid unnecessary confusion of the embodiments described herein. The examples provided herein are intended only to facilitate understanding of methods that can be practiced or utilized in the embodiments herein. The description should not be interpreted as limiting the scope of the embodiments herein.

[0020] In one aspect, the present subject matter contemplates a silicone-free and fluorine-free release coating composition. The release coating composition of the present invention is coated on a substrate including a face stock for a self-wrap laminate construction involving a coated adhesive (such as a pressure sensitive adhesive) without a liner, thereby providing excellent release properties. In addition, the release coating of the present invention is designed to be recyclable and can also be printed using some common printing methods known in the industry, especially in the label industry.

[0021] As used herein, the phrase "silicone-free" or "free of silicone" means a composition having less than about 0.5% by weight of silicone based on the total weight of the dry composition, preferably less than about 0.1% by weight of silicone based on the total weight of the dry composition, more preferably less than about 0.01% by weight of silicone based on the total weight of the dry composition, and most preferably about 0% by weight of silicone based on the total weight of the dry composition. As used herein, the phrase "fluorine-free" or "free of fluorine" means a composition having less than about 0.5% by weight of fluorine based on the total weight of the dry composition, preferably less than about 0.1% by weight of fluorine based on the total weight of the dry composition, more preferably less than about 0.01% by weight of fluorine based on the total weight of the dry composition, and most preferably about 0% by weight of fluorine based on the total weight of the dry composition.

[0022] According to one embodiment of the present invention, the silicone-free, fluorine-free peel coating composition includes at least one polymer binder; and one or more microbeads, such that the amount of the microbeads is in the range of 1 vol% to 85 vol% of the total dry volume of the peel coating composition. Typically, the ratio (v / v) of the amount of the microbeads to the amount of the polymer binder is in the range of 1:0.1 to 1:60.

[0023] The polymer base material according to the present invention includes but is not limited to at least one polymer selected from polyvinyl pyrrolidone, polyurethane, polyacrylate, sulfonated polyester, modified polyolefin, polyvinyl alcohol and combinations thereof. In an exemplary embodiment, the polymer base material is polyvinyl pyrrolidone. In another exemplary embodiment, the polymer base material is polyurethane. In still another exemplary embodiment, the polymer base material is polyacrylate.

[0024] In some embodiments, the polymer base includes a first polymer and a second polymer, wherein the first polymer is polyvinyl pyrrolidone and the second polymer is at least one polymer selected from the group consisting of polyurethane, polyacrylate, sulfonated polyester, modified polyolefin, polyvinyl alcohol and a combination thereof. The ratio (wt / wt) of the amount of the first polymer to the amount of the second polymer in the polymer base is in the range of 95:5 to 5:95. Preferably, the ratio (wt / wt) of the amount of the first polymer to the amount of the second polymer in the polymer base is in the range of 90:10 to 10:90, more preferably in the range of 80:20 to 20:80. In some embodiments of the present invention, the ratio (wt / wt) of the amount of the first polymer to the amount of the second polymer in the polymer base is 50:50.

[0025] Some polymer bases have good release properties but poor printing quality. Other polymers have good printing properties but high release force. By varying the ratio of the first polymer to the second polymer in the polymer base, the number of microbeads, and the size of the microbead particles, the properties of the release coating composition including release force, printability, and washability can be adjusted for the desired application.

[0026] Without being bound by theory, it is observed that polymer base materials with a certain weight average molecular weight can form a coating film after the coating is dried. Very low molecular weight polymers cannot form a cohesive film due to the low viscosity of these polymers. In addition, even if a film is formed, the film is unstable and easily cracks, peels off or breaks under stress. High molecular weight polymers have a higher viscosity, which brings difficulties to their processing and application. According to the present invention, the weight average molecular weight of the polymer base material is 10,000Da to 2000,000Da, preferably 50,000Da to 1000,000Da, and further preferably 100,000Da to 800,000Da, more preferably in the range of 400,000Da to 600,000Da.

[0027] According to the present invention, the glass transition temperature (Tg) of the polymer base material is higher than room temperature, usually 20° C. or higher. If the glass transition temperature (Tg) of the polymer is lower than room temperature, the formed coating film becomes sticky.

[0028] The peel coating composition of the present invention, which includes a specific polymer base material, has good adhesion to the substrate (such as the surface material used). The adhesion can be further enhanced by a primer coating or physical treatment of the substrate surface (such as corona treatment, plasma treatment, flame treatment, etc.). The adhesion of the peel coating was tested by applying 3M 810 tape to the peel coating surface and swiping it with the thumb about 20 times. After standing for 10 seconds, peel it off and visually check whether the coating peels off. If the coating peels off, the adhesion is not good, but if the coating does not peel off, the adhesion is good.

[0029] The peeling coating composition of the present invention including a specific polymer base has good ink anchoring and ink acceptance properties. The ink anchoring property of the peeling coating is tested by attaching 3M 810 tape to the printed ink surface of the peeling coating and swiping it 20 times with a thumb. After standing for 10 seconds, peel it off and visually observe whether the ink peels off. If it does not peel off, the anchoring is good. If the ink falls off, the ink anchoring of the peeling coating fails. When testing the ink acceptance, it can be visually observed whether the ink wets on the peeling coating surface. If wetting is complete, the ink acceptance of the peeling coating is good. The present invention also includes embodiments in which the surface of the peeling coating is exposed to various surface treatments (such as corona treatment) to improve the ink acceptance.

[0030] According to some embodiments, the polymer binder of the present invention includes polar groups on the polymer structure, such as OH-, COOH-, -COO-NH-, SO3-, -CO-NH- and -CO-NR, -Cl, -NH2, -NH-, -COOC- and -CO-O-CO-. The presence of polar groups in the polymer structure imparts polarity to the peeling coating, because the peeling coating is soluble in water or hot water or caustic water under certain conditions. The polar nature of the polymer binder improves the elution performance of the peeling coating composition.

[0031] The microbeads include, but are not limited to, at least one of glass beads, glass bubbles, alumina particles, aluminum hydroxide particles, and polymer beads (e.g., poly(methyl methacrylate) beads, polystyrene beads, poly(butyl methacrylate) beads). In one embodiment of the present invention, the microbeads are glass bubbles. In another embodiment of the present invention, the microbeads are glass beads. In still another embodiment of the present invention, the microbeads are polymer beads.

[0032] According to an embodiment of the present invention, the amount of microbeads is in the range of 1 vol% to 85 vol% of the total dry volume of the peeling coating composition. The volume percentage is calculated according to the following formula:

[0033] (W 珠 / bead density) / ((W 珠 / bead density)+(W 聚合物 / Polymer density))*100%

[0034] Among them, W 珠 is the bead weight, W 聚合物 is the polymer weight.

[0035] As for the upper limit, the amount of microbeads cannot be greater than 90 vol% of the total dry volume of the peeling coating composition. Above 90 vol%, the coating solution is in a paste state, which affects the coating quality and reduces the anchoring of the coating on the substrate or surface material. As for the upper limit, the amount of microbeads is less than 85 vol%, or less than 80 vol%, or less than 70 vol%, or less than 60 vol%, or less than 50 vol% of the total dry volume of the peeling coating composition. The amount of microbeads should be sufficient to maintain an adhesive peel force of no more than 1000 g / 2 inches. As for the lower limit, the amount of microbeads is at least 3 vol%, at least 7 vol%, at least 15 vol%, and at least 20 vol% of the total dry volume of the peeling coating composition. Preferably, the amount of microbeads is in the range of 5 vol% to 70 vol%, more preferably in the range of 10 vol% to 50 vol%.

[0036] According to an embodiment of the present invention, the microbeads have an average particle size (D50) in the range of 5 μm to 100 μm. D50 is the particle size corresponding to when the cumulative percentage reaches 50%. D50 is also called the median particle size or median particle size. For example, for a powder sample with D50 = 5 μm, it means that 50% of the particles are larger than 5 μm and 50% of the particles are smaller than 5 μm.

[0037] In terms of upper limits, the average particle size may be less than 90 μm, less than 70 μm, less than 60 μm, or less than 50 μm. Considering the thickness of adhesives for label, tape, graphic and decal applications, the average particle size is greater than 5 μm, typically greater than 10 μm, or even 20 μm. Preferably, the average particle size of the microbeads is in the range of 10 μm to 90 μm, more preferably 15 μm to 70 μm, and most preferably 20 μm to 50 μm.

[0038] Considering the printing properties required of the release coating composition, the microbead size cannot be infinitely large. It has been found that the maximum size is less than 70 μm, more preferably less than 60 μm, and more preferably less than 50 μm. Therefore, the release coating composition combining a polymer binder and microbeads of a specific size results in a release coating composition that exhibits the desired release properties as well as printability, cost-effectiveness and sustainability without silicone and fluorine compounds, all of which are described below.

[0039] Usually, the peeling coating composition is applied to surfaces such as paper, plastics and other films to produce non-stick surfaces, or to realize the installation of viscous materials (such as adhesive layer) by providing a protective covering. When the adhesive layer is intended to be exposed to adhere to a given substrate, the non-stick surface provided by these coatings allows adhesive and other viscous materials to be easily peeled off and separated. It can be considered that in order to obtain the required disengagement performance, the selected microbead particle size should be larger than the thickness of the adhesive layer contacted with the peeling coating. The larger the average particle size (D50) of microbead (exceeding the adhesive layer thickness), the smaller the peeling force required for separating the adhesive layer.

[0040] The average particle size of the microbeads is selected so that a random microstructure is formed on the coating surface, which can reduce the contact area between the coating surface and the adhesive layer covered by the peeling coating composition. Typically, the average particle size (D50) of the microbeads is such that the ratio of the particle size of the microbeads to the thickness of the adhesive layer contacting the peeling coating is at least 0.9, at least 1.0, at least 1.1, at least 1.2, at least 1.3, at least 1.5, at least 2.0, at least 2.5, at least 3.0, at least 3.5 or at least 4.0. In some embodiments of the present invention, the ratio of the average particle size (D50) of the microbeads to the thickness of the adhesive layer is at least 0.9. In a preferred embodiment of the present invention, the ratio of the average particle size (D50) of the microbeads to the thickness of the adhesive layer is in the range of 1.5 to 4.0.

[0041] According to some embodiments of the present invention, the silicone-free, fluorine-free release coating composition further comprises at least one additive selected from the group consisting of a deformation agent, a rheology modifier, a dispersant, a pH modifier, an antimicrobial agent, an antistatic agent, and a crosslinking agent.

[0042] The peel coating compositions of the present invention are used in different applications, including but not limited to labels and tapes, which are further divided into labels on paper / cardboard, labels on glass or plastic, automatically dispensed labels, linerless labels, packaging tapes, automotive tapes, masking tapes, medical tapes and duct tapes. Each application has different requirements for peel force. Generally, for tape applications, which include packaging tapes, automotive tapes and duct tapes, the required peel force is greater than 1000g / 2in. For masking tapes, the required peel force is slightly lower, generally in the range of 200-700g / 2in. For medical applications, where the tape is typically attached to the skin, the required peel force is very low, in the range of 10-500g / 2in. For different label applications, the required peel force is in the range of 10-1000g / 2in, and generally, for automatically dispensed label applications, the required peel force is less than 200g / 2in.

[0043] Without being bound by theory, it has been surprisingly found that a specific combination of a high surface energy polymer binder and microbeads results in a peel-coat composition that exhibits desired peeling properties required for different applications. By varying the ratio of polymer binder to microbeads and / or the size of the microbeads, the peeling properties of the peel-coat composition are adjusted to the desired application. In addition, the peel-coat composition of the present invention is free of silicone and fluorine, thereby providing an economical, environmentally friendly peel-coat composition.

[0044] The specific combination of a high surface energy polymer binder and microbeads having a specific particle size results in a release coating composition of the present invention that exhibits desired release properties and is printable. Surface energy (also known as interfacial free energy or surface free energy) quantifies the disruption of intermolecular bonds that occurs when a surface is created. The main components of the total surface energy are dispersive surface energy and polar surface energy. Dispersive surface energy (also known as surface dispersion energy) refers to the energy associated with van der Waals forces or London forces that act specifically on the surface of a material or liquid. These forces are generated due to temporary fluctuations in the distribution of electrons inside atoms and molecules, resulting in temporary dipoles. Polar surface energy is the component of surface energy generated by non-London forces or non-dispersive forces between molecules (such as acid-base interactions, dipole-dipole interactions, and hydrogen bonding interactions).

[0045] According to the present invention, the peel-coating composition comprising a polymer binder and microbeads exhibits an increased surface dispersion energy (in one embodiment, the dispersion energy is 39-41 mN / m) compared to the peel-coating composition comprising only a polymer binder (the dispersion energy is 31-34 mN / m), which results in a printable peel-coating composition. However, at the same time, the polar surface energy of the peel-coating composition is reduced (in one embodiment, the dispersion energy is 20-22 mN / m) compared to the peel-coating composition comprising only a polymer binder (the dispersion energy is 31-33 mN / m), which results in a desired peeling performance (in one embodiment, <1000 g / 2in) compared to the polymer binder alone (>2000 g / 2in). It is believed that since the combination still maintains a higher total surface energy (in one embodiment, the total surface energy is 60-63 mN / m) compared to the polymer base alone (the total surface energy is 62-68 mN / m), the ink printability is still good, and the surface containing the microstructure helps to reduce the peel force, providing good peeling performance.

[0046] According to an embodiment of the present invention, a polymer base material having a specific molecular weight can form a coating film after the coating is dried. Similarly, a polymer base material having a specific glass transition temperature (Tg) can avoid the formed coating film from being sticky at room temperature. The polymer base material as described in the present invention exhibits good adhesion properties as well as good ink anchoring and ink acceptance properties.

[0047] The release coating composition can be applied to a substrate such as a facestock using any coating technique known in the art (such as, but not limited to, rod coating, roller coating, gravure coating, multi-roll coating, reverse roller, air knife, wire wound rod, doctor blade, etc.) and other coating processes.

[0048] According to another aspect of the present invention, a release liner is provided. The release liner comprises a substrate having a first side and a second side; and a release coating composition comprising at least one polymer base and one or more microbeads, wherein the amount of the microbeads ranges from 1 vol% to 85 vol% of the total dry volume of the release coating composition. Typically, the substrate comprises at least one selected from paper or a polymer film.

[0049] According to another aspect of the present invention, a laminate is provided. The laminate comprises a face stock having a first side and a second side; a pressure-sensitive adhesive disposed on the first side of the face stock; optionally, a release liner at least partially covering the adhesive disposed on the face stock; and a release coating composition coated on at least one of the second side of the face stock or the adhesive-covered side of the release liner. The release coating composition comprises at least one polymeric binder and one or more microbeads, wherein the amount of the microbeads is in the range of 1 vol% to 85 vol% of the total dry volume of the release coating composition.

[0050] According to one embodiment, the laminate comprises a face material having a first side and a second side; a pressure-sensitive adhesive disposed on the first side of the face material; and a release liner at least partially covering the adhesive disposed on the face material; wherein the release coating composition of the present invention is coated on the adhesive-covered side of the release liner.

[0051] According to another embodiment, a laminate comprises a face stock having a first side and a second side; and a pressure sensitive adhesive disposed on the first side of the face stock; and wherein the release coating composition of the present invention is coated on the second side of the face stock.

[0052] Typically, the surface material includes but is not limited to a single-layer material or a multilayer material. The surface material is at least one substrate selected from paper or a polymer film. The polymer film is selected from a polyester film such as polyethylene terephthalate film (PET), polybutylene terephthalate (PBT) film and polyethylene naphthalate (PEN) film, polyethylene film (PE), polypropylene film (PP), polyethylene-polypropylene copolymer film or blended film, polyvinyl chloride film (PVC), polyimide film (PI), polyurethane film (PU), polycarbonate film (PC), polymethyl methacrylate film (PMMA), polyamide film (PA), metallized film, acrylic resin film, acrylic-urethane copolymer film, surface coating polymer film (such as primer coating film) and the like. Paper includes surface coating paper such as craft paper, medium gloss paper, kraft paper, silk paper, colored paper, semi-gloss paper, high gloss paper, foil and metallized paper, hemp paper, glass paper, primer coated paper, etc.

[0053] According to one embodiment of the present invention, the pressure-sensitive adhesive includes, but is not limited to, a solvent-based adhesive, an emulsion-based adhesive, a hot melt adhesive, or an adhesive activated by heat, moisture or external stimulation, a semi-structural adhesive, a structural adhesive. Typically, the thickness of the adhesive layer coated on the surface material is in the range of 2 μm to 40 μm, preferably 5 μm to 50 μm, more preferably 8 μm to 25 μm, and most preferably 10 μm to 20 μm.

[0054] The laminate of the present invention has a peel force ranging from 1 g / 2 inch to 1000 g / 2 inch tested at 90° peel force, 300 inch / min peel speed, 2 inch width specimen and 24 hour dwell time at room temperature.

[0055] Importantly, the inventors of the present invention have discovered that a release liner having a release coating composition involving at least one polymer binder and at least one microbead is recyclable under a recycling process. In addition, it has been discovered that the release coating is printable and does not present printing problems associated with silicone-containing release liners. The release coating composition can be printed using a variety of printing methods, including UV flexographic printing, water-based flexographic printing, UV relief printing, digital printing, UV inkjet printing, solvent-based inkjet printing, screen printing, offset printing, gravure printing, and the like.

[0056] The present invention will be further described by the following non-limiting examples. Different samples of the peel-coat composition of the present invention comprising different polymer binders and different particle sizes and different amounts (volume percentage of total dry volume) of microbeads were prepared and tested for their performance in terms of peel force, washability (recyclability), ink receptivity and ink anchoring.

[0057] The bead volume percentage was calculated according to the following formula:

[0058] (W珠 / bead density) / ((W 珠 / bead density)+(W 聚合物 / Polymer density))*100%

[0059] Among them, W 珠 is the bead weight, W 聚合物 is the polymer weight.

[0060] Different samples including different polymer bases and one of PBMA beads or glass bubbles as microbeads were prepared and tested for peel force by the method given below.

[0061] Stripping force test: The stripping coating composition was coated on a 50 μm PET film to form a stripping liner. In an exemplary embodiment, a laminate was prepared by laminating a 50 μm PET tape with a 22 μm acrylic adhesive SR207 (Avery Dennison) to the stripping coating surface of the stripping liner prepared above using a 2 kg roller. The obtained laminate was placed at room temperature for 24 hours and the stripping force was tested. The stripping test was performed using a 90° peeling force at a stripping speed of 300 inches / min and a 2-inch wide specimen. The results of the obtained stripping force values ​​(g / 2 inches) are shown in Table 1 below:

[0062]

[0063] Different samples including different polymer bases and glass bubbles as microbeads were prepared and tested for elution performance (recoverability) by the following method.

[0064] Recyclability test: The recyclability of the release liner (PET as substrate) coated with the release coating composition of the present invention was tested by eluting the release coating composition. The hot washing liquid (sodium hydroxide solution) in the washing tank was stirred at 240 rpm by a magnetic stirrer, and the washing liquid tank was kept at a temperature of 85°C ± 1°C for a certain period of time. The shorter the time required to remove the release coating composition from the substrate, the better the elution performance. The washing liquid can be 1-4%wt, preferably 1-2%wt alkaline water, that is, an alkaline aqueous solution including caustic soda (such as sodium hydroxide). The elution results obtained are shown in Table 2 below:

[0065]

[0066] × - poor performance (>1hr); △ - average performance (15min-1hr); □ - good performance (5min-15min); and ◎ - best performance (<5min)

[0067] Release coating compositions including polyvinyl pyrrolidone as a polymer binder and glass microspheres as microspheres were prepared and tested for their printability properties using different printing techniques.

[0068] Ink anchoring test: 3M 810 tape is attached to the surface of the peeling coating printed ink and the thumb is used to swipe it 20 times to test the ink anchoring property of the peeling coating composition. After standing for 10 seconds, peel it off and visually check whether the ink peels off. If it does not peel off, the anchoring is good. If the ink falls off, the ink anchoring of the peeling coating fails.

[0069] Ink receptivity: When testing ink receptivity, it is visually checked whether the ink wets the release coating surface. If wetting is complete, the release coating has good ink receptivity. The ink receptivity and ink anchoring results for different printing techniques are as follows

[0070] As shown in Table 3:

[0071]

[0072] Tables 4a and 4b represent the effects of different polymer binders and different microbeads of different particle sizes and amounts (volume percentage of total dry volume) on the release force, recyclability (wash-off performance) and printability properties of the release coating compositions of the present invention.

[0073]

[0074]

[0075]

[0076] Table 5 shows the effect of binder combination on the performance of the release coating composition.

[0077]

[0078]

[0079] Table 6 shows the effect of microbead size and microbead quantity on the performance of the release coating composition. Different samples including different quantities of glass bubbles with different particle sizes were prepared and tested for release force, wash-off performance and printability.

[0080]

[0081]

[0082] When the bead volume is greater than 90 vol% of the total dry volume, the coating solution exhibits a paste-like consistency and results in poor anchoring of the coating composition on the substrate or facestock. To further maintain a peel force <1000 g / 2in, for an average bead size >= 40 um, the bead volume should be no less than 7 vol% of the total dry volume; for an average bead size <40 um, the bead volume should be greater than 20 vol%, or even greater than 50 vol% of the total dry volume. The bead size to adhesive thickness ratio should be at least 0.9.

[0083] Table 7 presents the effect of polymer bead size and polymer bead quantity on the performance of the release coating composition. Different samples including polymer beads of different sizes were prepared and tested for release force, wash-off performance and printability.

[0084]

[0085]

[0086] It can be observed from the above table that the smaller the contact area between the adhesive and the release surface, the smaller the release force and vice versa.

[0087] Table 8 represents a linerless laminate (referred to as a linerless label) comprising a face stock having a first side and a second side; a pressure sensitive adhesive disposed on the first side of the face stock; and a release coating composition coated on the second side of the face stock. A release coating composition comprising a polymer base polyvinylpyrrolidone (PVP) and glass beads having a particle size of D50 = 40 μm (% volume of total dry volume) was tested. The release of the laminate by laminating the adhesive side of the linerless laminate to the release side of the linerless laminate using a 2 kg roller was then tested at room temperature for 24 hours. The release test was performed using a 90° peel force, a peel speed of 300 inches / min and a specimen of 2 inches in width. Adhesion of the adhesive was performed using a ring bond method on stainless steel (SS) at room temperature for 24 hours and a 90° peel strength on stainless steel at room temperature for 24 hours. The expected results of the peel force values ​​(g / 2 inch) obtained are shown in Table 8.

[0088]

[0089] Table 9 presents the effect of microbead incorporation on the surface energy of the polymer base.

[0090]

[0091] It can be observed from Table 9 that the addition of microbeads to a high surface energy binder increases the dispersive surface energy of the coating and reduces the polar surface energy without affecting the total surface energy. The resulting release coating composition is printable and has a low release force.

Claims

1. A silicone-free release coating composition comprising: at least one polymer binder; and one or more microbeads; The amount of the microbeads is in the range of 1 vol% to 85 vol% of the total dry volume of the peel-coating composition.

2. The peel-coating composition according to claim 1, wherein the polymer base is at least one polymer selected from the group consisting of polyvinyl pyrrolidone, polyurethane, polyacrylate, sulfonated polyester, modified polyolefin, polyvinyl alcohol and combinations thereof.

3. The release coating composition of claim 1, wherein the polymer binder comprises a first polymer and a second polymer.

4. The peel-coating composition according to claim 3, wherein the first polymer is polyvinyl pyrrolidone, and the second polymer is selected from the group consisting of polyurethane, polyacrylate, sulfonated polyester, modified polyolefin, polyvinyl alcohol, and combinations thereof. 5 . The peel-coating composition according to claim 3 , wherein the ratio (wt / wt) of the amounts of the first polymer and the second polymer in the polymer base is in the range of 95:5 to 5:

95. 6 . The peel-coating composition according to claim 3 , wherein the ratio (wt / wt) of the amounts of the first polymer and the second polymer in the polymer base is in the range of 80:20 to 20:

80. 7 . The peel-coating composition according to claim 1 , wherein the microbeads are selected from the group consisting of glass beads, glass bubbles, polymer beads, aluminum oxide particles, aluminum hydroxide particles, and combinations thereof.

8. The release coating composition of claim 7, wherein the polymer beads are one of poly(methyl methacrylate) beads, polystyrene beads, or poly(butyl methacrylate) beads. 9 . The peel-coating composition according to claim 1 , wherein the amount of the microbeads ranges from 5 vol % to 70 vol % of the total dry volume of the peel-coating composition. 10 . The peel-coating composition according to claim 1 , wherein the amount of the microbeads ranges from 10 vol % to 50 vol % of the total dry volume of the peel-coating composition. 11 . The peel-coating composition according to claim 1 , wherein the microbeads have an average particle size ranging from 5 μm to 100 μm. 12 . The peel-coating composition according to claim 1 , wherein the microbeads have an average particle size ranging from 20 μm to 50 μm. 13 . The peel-coating composition according to claim 1 , wherein a ratio (v / v) of the amount of the microbeads to the amount of the polymer binder is in the range of 1:0.1 to 1:

60. 14 . The peel-coating composition according to claim 1 , wherein a ratio (v / v) of the amount of the microbeads to the amount of the polymer binder is in the range of 1:0.2 to 1:

20.

15. The peel-coating composition according to claim 1, wherein the coating composition is free of silicone and fluorine.

16. The peel-coating composition of claim 1, wherein the coating composition further comprises at least one additive.

17. The peel-coating composition according to claim 16, wherein the additive is at least one selected from the group consisting of a deformation agent, a rheology modifier, a dispersant, a pH modifier, an antibacterial agent, an antistatic agent, a crosslinking agent, and combinations thereof.

18. A release liner comprising: a substrate having a first side and a second side; and The release coating composition of any of the preceding claims, coated on at least one of the first side and the second side of the substrate.

19. The release liner according to claim 18, wherein the substrate is at least one selected from the group consisting of paper and polymer films.

20. A laminate comprising: a face material having a first side and a second side; a pressure sensitive adhesive disposed on the first side of the facestock; Optionally, a release liner at least partially covering the adhesive disposed on the facestock; and The release coating composition of any of the preceding claims, coated on at least one of the second side of the facestock or the adhesive-covered side of the release liner.

21. The laminate according to claim 20: wherein there is a release liner covering the adhesive; and wherein the release coating composition of any one of the preceding claims is coated on the adhesive-covered side of the release liner.

22. The laminate according to claim 20: The release coating composition of any one of the preceding claims is coated on the second side of the facestock.

23. The laminate of claim 20, wherein the face material is a single layer material or a multi-layer material.

24. The laminate of claim 20, wherein the face stock comprises at least one material selected from the group consisting of paper, polymer films, and combinations thereof.

25. The laminate according to claim 24, wherein the polymer film is at least one film selected from the group consisting of polyester films, polyolefin films, polyethylene terephthalate films, polyethylene films, polypropylene films, polyvinyl chloride films, polyurethane films, polyacrylic films, acrylate-urethane copolymer films, metallized films, primer-coated polymer films, and combinations thereof.

26. The laminate according to claim 24, wherein the paper is at least one paper selected from the group consisting of craft paper, medium gloss paper, kraft paper, silk paper, colored paper, semi-gloss paper, high gloss paper, foil, metallized paper, hemp paper, glassine paper, primer coated paper and combinations thereof.

27. The laminate of claim 20, wherein the pressure sensitive adhesive is at least one adhesive selected from the group consisting of solvent-based adhesives, emulsion-based adhesives, hot melt adhesives, heat-activated adhesives, semi-structural adhesives, structural adhesives, and combinations thereof.

28. The release liner of claim 20, wherein the release coating composition has a release force in a range of 1 g / 2 inch to 1000 g / 2 inch.

29. The release liner of claim 18 is recyclable.

30. The release liner of claim 18 which is printable.

31. The laminate of claim 20 which is printable.

Images