Process for manufacturing laminated sheets

Abstract

One process for producing a laminated sheet may include: applying an uncured adhesive to a removable layer such that a first surface of the removable layer is in direct contact with the uncured adhesive; curing the uncured adhesive to form a cured adhesive layer located in direct contact with the first surface of the removable layer; and applying a release liner in direct contact with the cured adhesive layer such that the cured adhesive layer is located between the removable layer and the release liner. Another process for producing a laminated sheet may include: applying an uncured adhesive to a release liner such that a first surface of the release liner is in direct contact with the uncured adhesive; curing the uncured adhesive to form a cured adhesive layer located in direct contact with the first surface of the release liner; and applying a removable layer in direct contact with the cured adhesive layer such that the cured adhesive layer is located between the removable layer and the release liner. The release liner may include a copolymer comprising low-density polyethylene and one or more functionalized polysiloxanes. The functionalized polysiloxanes may be selected from (meth)acrylic acid ester functionalized polysiloxanes and vinyl functionalized polysiloxanes.

Description

[Technical Field]

[0001] (Cross-reference of related applications) This application claims the benefits of U.S. Provisional Application No. 63 / 511,044, filed on 29 June 2023, the entirety of which is incorporated herein by reference.

[0002] (Field of invention) This disclosure relates, in general terms, to laminated sheets, and more specifically, to methods for manufacturing laminated sheets. [Background technology]

[0003] Laminated sheets have a wide variety of applications in industry. For example, some laminated sheets may have selectively removable layers, such as stickers or labels. These stickers or labels can be removed from the backing film when desired by the user and then applied to a substrate. Such laminated sheets can be used for many decorative and functional purposes and can be varied in color and design. For example, labels on packaging, food, or other consumer products are widely used in industry. However, novel and / or improved methods for producing laminated sheets are desired. [Overview of the project]

[0004] Embodiments of this disclosure can satisfy these needs by providing a novel process for producing laminated sheets utilizing a special copolymer composition in a release liner. The laminated films described herein may generally include a release liner, an adhesive, and a removable layer. Such embodiments can be used as stickers and / or labels, in which case the removable layer and adhesive are separated from the release liner. The copolymer compositions described herein incorporate (meth)acrylic acid ester-functionalized polysiloxanes. In such embodiments, the release liner does not require a special top coating such as silicone, as is common in conventional embodiments. Instead, the copolymer can have acceptable release properties without requiring other special layers that add cost and complexity to the process.

[0005] According to one or more embodiments of the present disclosure, a process for producing a laminated sheet may include: applying an uncured adhesive to a removable layer such that a first surface of the removable layer is in direct contact with the uncured adhesive; curing the uncured adhesive to form a cured adhesive layer located in direct contact with the first surface of the removable layer; and applying a release liner in direct contact with the cured adhesive layer such that the cured adhesive layer is located between the removable layer and the release liner. The release liner may include a copolymer comprising low-density polyethylene and one or more functionalized polysiloxanes. The functionalized polysiloxane may be selected from (meth)acrylic acid ester functionalized polysiloxanes and vinyl functionalized polysiloxanes.

[0006] According to one or more additional embodiments of the present disclosure, a process for producing a laminated sheet may include: applying an uncured adhesive to a release liner such that a first surface of the release liner is in direct contact with the uncured adhesive; curing the uncured adhesive to form a cured adhesive layer located in direct contact with the first surface of the release liner; and applying a removable layer in direct contact with the cured adhesive layer such that the cured adhesive layer is located between the removable layer and the release liner. The release liner may comprise a copolymer comprising low-density polyethylene and one or more functionalized polysiloxanes. The functionalized polysiloxanes may be selected from (meth)acrylic acid ester functionalized polysiloxanes and vinyl functionalized polysiloxanes.

[0007] These and other embodiments are described in more detail in “Modes for Carrying Out the Invention.” It should be understood that both the above general description and the following detailed description represent embodiments of the technology and are intended to provide an overview or framework for understanding the nature and features of the technology as claimed. The accompanying drawings are included to provide a further understanding of the technology and are incorporated herein and constitute part thereof. The drawings illustrate various embodiments and, together with the description, help to illustrate the principles and operation of the technology. Additionally, the drawings and description are intended to be illustrative only and are not intended to limit the scope of the claims in any way. [Brief explanation of the drawing]

[0008] The following “Modes for Carrying Out the Invention” of specific embodiments of this disclosure will be best understood in conjunction with the following drawings, in which similar structures are shown with similar reference numerals. [Figure 1] This is a schematic flowchart of a process for producing a laminated sheet according to one or more embodiments disclosed herein. [Figure 2] This is a schematic flowchart of a process for producing a laminated sheet according to one or more embodiments disclosed herein. [Figure 3]This is a schematic diagram of a continuous process for producing laminated sheets according to one or more embodiments disclosed herein.

[0009] Additional features and advantages of this disclosure are described in the following “Modes for Carrying Out the Invention” and will be partially apparent to those skilled in the art from that description, or will be recognized by practicing the embodiments described herein, including the “Modes for Carrying Out the Invention,” the following claims, and the accompanying drawings.

[0010] It should be understood that both the general description above and the detailed description below are intended to describe various embodiments and provide an overview or framework for understanding the nature and features of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments and are incorporated into and form part of this specification. The drawings illustrate the various embodiments described herein and, together with the descriptions, illustrate the principles and operation of the claimed subject matter. [Modes for carrying out the invention]

[0011] Herein, specific embodiments of the present application are described. However, the present disclosure may be embodied in different forms and should not be construed as being limited to the embodiments described herein. Rather, these embodiments are provided so that the present disclosure may be thorough and complete and so as to fully convey the scope of the subject matter to those skilled in the art.

[0012] This specification describes a process for producing a laminated sheet comprising a release liner, a central adhesive layer, and a removable layer (sometimes referred to in the industry as a face stock). Such a laminated sheet may be used to fix a removable layer, such as a sticker or other label, before application to a product. As described herein, according to the embodiments, the unique composition of the release liner offers advantages compared to conventional release liners, and in some embodiments, makes manufacturing easier and less expensive.

[0013] Figure 1 provides a schematic diagram of a first embodiment of one or more processes described herein, in which an adhesive is applied to a removable layer, and then a release liner is applied to the adhesive layer after the adhesive layer has cured.

[0014] Referring in detail to Figure 1, a removable layer 110 is shown to the left of process 100. The removable layer 110 (shown as an uncoated removable layer 210) may include a first surface 114 opposite the second surface 112. The removable layer 110 may have the shape of a sheet with dimensions much larger in the length and width directions than in the thickness direction. The removable layer 110 may also be a sticker or label, sometimes called a face stock. For example, the removable layer 110 may include, but is not limited to, paper, vinyl, polyester, polypropylene, foil, fabric, or a combination thereof. The removable layer 110 may be a composite layer or laminated layer having multiple sublayers. However, the material of the removable layer 110 is not necessarily limited to the material in the embodiments described herein.

[0015] Referring further to Figure 1, the process 100 for producing the laminated sheet may include applying an uncured adhesive 120 to the removable layer 110 such that the first surface 114 of the removable layer 110 is in direct contact with the uncured adhesive 120 (shown as a coated removable layer 220). For example, the uncured adhesive 120, which is typically in liquid phase, may include surfaces 122 and 124, with surface 122 in direct contact with the first surface 114 of the removable layer 110. The composition of the adhesive is not necessarily limited, and it is intended that many types and grades of adhesives may be applied. Not limited to, but intended adhesives include acrylic adhesives, rubber adhesives, hot melt adhesives, water-based adhesives, solvent-based adhesives, pressure-sensitive adhesives, and synthetic rubber adhesives.

[0016] Referring further to Figure 1, process 100 may further include curing the uncured adhesive 120 to form a cured adhesive layer 140 located in direct contact with the first layer 114 of the removable layer 110. The cured, coated, removable layer 230 is shown. The cured, coated, removable layer 240 after the curing step is shown. As described herein, curing is a process of inducing chemical reactions in a material, typically a polymer, to change the material properties and / or to promote adhesion to a substrate. During curing, polymer chains can crosslink with each other to increase molecular weight and form a solid, durable structure. Curing can be achieved by various methods, depending on the composition of the adhesive material, including exposure to heat, radiation (e.g., visible or UV light), or a chemical catalyst. The resulting cured material may typically have greater resistance to chemical and physical degradation and exhibit improved strength, flexibility, and other desirable properties. Light 150 represents the heat or light that can be used for curing.

[0017] Process 100 may further include applying the release liner 130 in direct contact with the curing adhesive layer 140 such that the curing adhesive layer 140 is located between the removable layer 110 and the release liner 130 (shown as a laminated sheet 250 in Figure 1). The release liner 130 may include a first surface 134 opposite to a second surface 132. The release liner 130 may have the shape of a sheet with dimensions much larger in the length and width directions than in the thickness direction. As described in detail herein, the release liner 130 may include a polymer composition comprising polyethylene, a reaction product of copolymerization of ethylene and (meth)acrylic acid ester-functionalized polysiloxane, and optionally one or more units derived from ter monomers. This polymer composition, along with its functional groups, will be disclosed in detail later herein.

[0018] Generally, the release liner 130 can have a uniform composition throughout its body. That is, the release liner 130 may not include multiple material layers such as a substrate and a separate silicone layer. Thus, the processes of the present disclosure can avoid the silicone liner application step that is common in conventional embodiments. For example, conventional processes can apply liquid silicone to a substrate sheet and then cure the silicone in an oven to arrive at an equivalent of the release liner 130.

[0019] FIG. 2 provides a schematic view of a second embodiment of one or more of the processes described herein, where an adhesive is applied to a release liner and then a removable layer is applied over the adhesive layer after curing of the adhesive layer.

[0020] Referring now in detail to FIG. 2, a release liner 211 is shown on the left side of process 200. The release liner 211 (shown as an uncoated release liner 260) can include a first surface 212 on the opposite side of the second surface 214. The release liner 211 can have the shape of a sheet having dimensions that are much larger in the length and width directions than in thickness. As described in detail herein, the release liner 211 can include a polymer composition that includes polyethylene, a reaction product of a copolymerization of ethylene and a (meth)acrylate-functionalized polysiloxane, and optionally one or more units derived from a comonomer. This polymer composition, along with its functional groups, is disclosed in detail later herein. That is, the release liner 211 may not include multiple material layers such as a substrate and a separate silicone layer. Thus, the processes of the present disclosure can avoid the silicone liner application step that is common in conventional embodiments. For example, conventional processes can apply liquid silicone to a substrate sheet and then cure the silicone in an oven to arrive at an equivalent of the release liner 211.

[0021] Referring further to FIG. 2, process 200 for making the laminate sheet may include applying uncured adhesive 215 to release liner 211 such that the first surface 212 of release liner 211 is in direct contact with uncured adhesive 215 (shown as coated release liner 270). For example, uncured adhesive 215, which is typically in a liquid phase, may include surfaces 216 and 218, and surface 216 is in direct contact with the first surface 212 of release liner 211. The composition of the adhesive is not necessarily limited, and it is contemplated that many types and grades of adhesives may be applied. Non-limiting examples of contemplated adhesives include acrylic adhesives, rubber adhesives, hot melt adhesives, water-based adhesives, solvent-based adhesives, pressure-sensitive adhesives, and synthetic rubber adhesives.

[0022] Referring further to FIG. 2, process 200 may further include curing uncured adhesive 215 to form cured adhesive layer 217 positioned in direct contact with the first layer 212 of release liner 211. Coated release liner 280 undergoing curing is shown. Cured, coated release liner 290 after the curing step is shown. As described herein, curing is a process that induces a chemical reaction in a material, typically a polymer, to change its physical properties and / or to promote adhesion to a substrate. During curing, polymer chains can crosslink with each other to increase the molecular weight and form a durable solid structure. Curing can be achieved by various methods, including exposure to heat, radiation (e.g., visible light or UV light), or chemical catalysts, depending on the composition of the adhesive material. The resulting cured material typically has increased resistance to chemical and physical degradation and may exhibit improved strength, flexibility, and other desirable properties. Light ray 205 is representative of the heat or light that may be utilized for curing.

[0023] Process 200 may further include applying the removable layer 219 in direct contact with the curing adhesive layer 217 such that the curing adhesive layer 217 is located between the removable layer 219 and the release liner 211 (shown as a laminated sheet 300 in Figure 2). The removable layer 219 may include a first surface 221 opposite to a second surface 222. The removable layer 219 may have the shape of a sheet with dimensions much larger in the length and width directions than in the thickness direction. The removable layer 219 may also be a sticker or label, sometimes called a face stock. For example, the removable layer 219 may include, but is not limited to, paper, vinyl, polyester, polypropylene, foil, fabric, or a combination thereof. The removable layer 219 may also be a composite layer or laminated layer having multiple sub-layers. However, the material of the removable layer 219 is not necessarily limited to the material in the embodiments described herein.

[0024] According to additional embodiments, process 100 in Figure 1 or process 200 in Figure 2 may be performed as a continuous process. For example, Figure 3 shows the formation of a laminated sheet in a continuous process by process 100 in Figure 1. As shown in Figure 3, the roll 310 can hold the uncoated removable layer 210. The uncoated removable layer 210 may move in the machine direction toward a coating apparatus 320 which can supply the uncured adhesive 120. As described herein, the machine direction refers to the direction in which the removable layer 110 moves toward or toward any roller or processing machine such as a coating apparatus 320 or a curing apparatus 330, as described later herein. The machine direction may differ in different parts of the process, such as when the roller reorients the directional movement of the removable layer 110, as shown in Figure 3.

[0025] As shown in Figure 3, the uncoated removable layer 210 may be sent to a coating apparatus 320, where the uncured adhesive 120 may be applied to the removable layer 110 as it moves parallel to the machine. The coating apparatus 320 may include two wheels, one of which applies the uncured adhesive 120, although this is not necessarily limited to its structure or function, in some embodiments. Following processing in the coating apparatus 320, the coated removable layer 220 is sent to a curing apparatus 330. In the curing apparatus 330, curing the uncured adhesive 120 to form a cured adhesive 140 may occur as the removable layer 110 moves parallel to the machine. The curing apparatus 330 may include an oven, light, or any other suitable equipment that affects the curing of the uncured adhesive 120.

[0026] Following processing in the curing apparatus 330, the cured, coated, removable layer 240 may be sent to a joint where a release liner 130 is applied to the cured, coated, removable layer 240 to form a laminated sheet 250. The release liner 130 may be stored on a roll 340, and the laminated sheet 250 may ultimately be stored on a roll 350. In such embodiments, the release liner 130 may be applied as the removable layer 110 moves parallel to the machine direction. Downstream in Figure 3, the laminated sheet 250 may be cut and / or the removable layer 110 may be separated from the release liner 130 along with the curing adhesive 140. The laminated sheet can be formed via a similar continuous process as shown in process 200 of Figure 2.

[0027] Figure 3 shows the configuration of Figure 1, but those skilled in the art can implement the apparatus of Figure 3 for the configuration of Figure 2, and such embodiments are contemplated herein.

[0028] As described herein, the release liner 130 may contain, consist of, or essentially consist of a copolymer of low-density polyethylene (sometimes referred herein as "ethylene polymer" or "LDPE") and a functionalized polysiloxane such as a functionalized polydimethylsiloxane (sometimes referred herein as "f-PDMS"). In some examples, the copolymer may be referred to as LDPE-co-PDMS, referring to a copolymer of f-PDMS and LDPE. However, when describing the attributes of LDPE-co-PDMS, it should be understood that embodiments containing siloxanes other than PDMS are sometimes intended to have the same attributes.

[0029] Unlike conventional embodiments, the release liners described herein generally have a homogeneous composition (e.g., a single layer). Conventional embodiments may utilize, for example, a silicone top coating to enable suitable release properties. However, it is found herein that the compositions disclosed herein, used in release liner 130, can provide suitable release properties without requiring an additional release layer such as a silicone layer.

[0030] In embodiments, copolymers may be formed by high-pressure free-radical polymerization by reacting an ethylene monomer with a functionalized polysiloxane, or by reacting a mixture of an ethylene monomer with a functionalized polysiloxane. In embodiments, the functionalized polysiloxane is bonded to the high-pressure ethylene polymer via several covalent bonds, which result from the reaction of the first functional group of the functionalized polysiloxane with the growing propagation chain of the ethylene polymer, followed by further reaction with the ethylene monomer, and may also include crosslinking between the functional group being polymerized and the siloxane.

[0031] In embodiments, the copolymer may contain, based on the total weight of the copolymer, 0.1% to 50% by weight of a functionalized polysiloxane such as f-PDMS, for example, 0.1% to 20% by weight, 0.5% to 20% by weight, 2.0% to 20% by weight, 2.0% to 15% by weight, 2.0% to 12% by weight, 2.0% to 10% by weight, 1.0% to 10% by weight, 5% to 10% by weight, or 5.0% to 20% by weight.

[0032] In various embodiments, the copolymer has the following structure:

[0033] [ka] (In the formula, R is methyl or hydrogen, R 1 R is a crosslinking group that links the functional group ((meth)acrylate) to the siloxane, 2 R is a terminal group selected from the group consisting of alkyl, substituted alkyl, aryl, alkenyl, H, and OH, where x is an integer from 10 to 1000, y is an integer from 1 to 30, z is an integer from 0 to 30, and r+z is 30 or less) and includes one or more of these. 1 and R 2 The bases may be the same or different.

[0034] In the embodiment, the crosslinking group of LDPE-co-PDMS is a substituted or unsubstituted C2-C group in which one or more carbon atoms may be substituted with oxygen and / or silicon, substituted or unsubstituted aryl groups, and their derivatives and combinations. 20 Alkylene linkers may be selected. In some embodiments, the functional group bonded to the crosslinking group may be bonded to a high-pressure ethylene polymer by copolymerization with an ethylene monomer. In various embodiments, the functional group is a (meth)acrylate ester group. In further embodiments, the crosslinking group is the group shown below:

[0035] [ka]

[0036] In the above structural formula, the ethylene polymer branch is indicated as polyethylene (PE), which may represent LDPE.

[0037] The copolymer may contain polysiloxane units, which in embodiments are derived from functionalized polydimethylsiloxane (e.g., f-PDMS). In embodiments, the functionalized polysiloxane may be (meth)acrylate ester functionalized polydimethylsiloxane (f-PDMS), in which (meth)acrylate functional groups are bonded to PDMS via crosslinking.

[0038] In the embodiment, the copolymer optionally comprises one or more units derived from a ter monomer. The ter monomer may be selected from the group consisting of olefins, unsaturated esters, unsaturated acids, functionalized alkenes, and combinations thereof.

[0039] Functionalized polysiloxanes Polysiloxanes can be any of a diverse class of polymers manufactured as fluids, resins, or elastomers. While polysiloxanes are partially organic compounds, unlike most polymers, they have a carbon-free backbone, as shown above, and instead consist of alternating silicon and oxygen atoms. In the structural formulas shown above, each silicon atom is shown to be bonded to a methyl and / or R group, but each of these positions is intended to be, individually, alkyl, vinyl, phenyl, hydrogen, hydroxyl, acetoxy, enoxy, oxime, methoxy, ethoxy, alkoxy, dimethylamino, aminopropyl, hydroxypropyl, mercaptopropyl, chloropropyl, acrylooxypropyl, methacrylateoxypropyl, epoxypropoxypropyl, or epoxycyclohexylethyl. In embodiments, each position is methyl.

[0040] In some embodiments, x is large enough so that the polysiloxane has a viscosity of 100 or more, 200 or more, or 500 or more centistokes (CST). In embodiments, x is not large enough to produce a polysiloxane with a viscosity of 2.5 million CST or less. However, the upper limit of viscosity is intended to be less than 2.5 million CST, for example, 1 million or 600,000 CST.

[0041] Examples of polysiloxanes suitable for use in various embodiments include those described in U.S. Patent No. 6,239,244, the full contents of which are incorporated herein by reference. Polysiloxanes are commercially available from several different manufacturers, including, but not limited to, Dow, Momentive, Wacker, Shin-Etsu, and Evonik.

[0042] According to the embodiment, the release liner may comprise a copolymer of low-density polyethylene and (a) (meth)acrylic acid ester-functionalized polysiloxane, (b) vinyl-functionalized polysiloxane, or a mixture thereof.

[0043] In the various embodiments described herein, the polysiloxane is a polydimethylsiloxane (PDMS) containing one or more functional groups, and is therefore referred to as functionalized PDMS or f-PDMS. In various embodiments, f-PDMS is a (meth)acrylate ester functionalized PDMS in which (meth)acrylate ester groups are bonded to the PDMS via crosslinking groups, or a vinyl functionalized PDMS in which vinyl groups are directly bonded to any of the silicon atoms of the PDMS. The PDMS may be monofunctional, difunctional, or polyfunctional, and the functional group(s) may be linked at terminal or pendant positions on the siloxane. Therefore, in embodiments, f-PDMS has the following structure:

[0044] [ka] (In the formula, R is methyl or hydrogen, R 1 is a crosslinking group, R 2 (where x is a terminal group selected from alkyl, aryl, alkenyl, H, or OH, and x is an integer from 10 to 1000, and y is an integer from 1 to 30) and includes one or a combination thereof.

[0045] Process-functionalized polysiloxane In various embodiments, each crosslinking group is determined by the way in which the siloxane skeleton is linked to the (meth)acrylate functional group. In some embodiments, the siloxane skeleton is linked to the (meth)acrylate functional group through direct hydrosilylation of the alkenyl (meth)acrylate, hydrosilylation using a SiH-functionalized (meth)acrylate converter, or equilibrium / condensation with a (meth)acrylate-functionalized alkoxysilane. Depending on the particular embodiment, other methods for linking the siloxane skeleton to the (meth)acrylate functional group may be contemplated and used.

[0046] Process - Copolymer of ethylene and functionalized polysiloxane In various embodiments, LDPE-co-PDMS is formed in the presence of ethylene. In embodiments, LDPE-co-PDMS is produced via a high-pressure free-radical polymerization process. Two different types of high-pressure free-radical initiated polymerization processes are known. In the first process type, a stirred autoclave reactor having one or more reaction zones is used. The autoclave reactor includes several injection points for initiators or monomer feeds, or both. In the second process type, a jacketed tube is used as the reactor, which has one or more reaction zones. Suitable reactor lengths include, but are not limited to, 100 to 3000 meters (m) or 1000 to 2000 m, and in either type of reactor, the initiation of the reaction zones is usually defined by side injection of a reaction initiator, ethylene, chain transfer agent (or telomer), comonomer(s), or a combination thereof. The high-pressure process can be carried out in an autoclave reactor or tubular reactor having one or more reaction zones, or in a combination of an autoclave reactor and a tubular reactor, each containing one or more reaction zones.

[0047] In various embodiments, chain transfer agents (CTAs) can be used to control polymer properties, including but not limited to the molecular weight and melt index of the resulting polymer. Chain transfer is associated with the cessation of polymer chain growth and therefore limits the final molecular weight of the polymer material. Chain transfer agents are typically hydrogen atom donors that react with the growing polymer chain and halt the polymerization reaction of the chain. In the case of high-pressure free-radical polymerization, CTAs can be many different types, such as saturated hydrocarbons, unsaturated hydrocarbons, aldehydes, ketones, or alcohols. Non-limiting examples of CTAs include propylene, isobutane, n-butane, 1-butene, methyl ethyl ketone, acetone, ethyl acetate, propionaldehyde, a product available under the trade name ISOPAR (available from ExxonMobil Chemical Co.), and isopropanol. In embodiments, the amount of CTA used in the process is 0.01% to 10% by weight of the total reaction mixture.

[0048] In embodiments, the free radical initiator may include CTA as a solvent or as a blend for co-injection with ethylene. For example, CTA can be blended with ethylene, pressurized, and then injected into the reactor.

[0049] In various embodiments, one or more free radical initiators are used to produce LDPE-co-PDMS. Commonly used free radical initiators for producing ethylene-based polymers such as LDPE are oxygen and peroxides. Non-limiting examples of free radical initiators include t-butyl peroxypivalate, di-t-butyl peroxide, t-butyl peroxyacetate (TPA), t-butyl peroxyoctoate (TPO), t-butyl peroxy-2-hexanoate, and combinations thereof. Other initiators known and used in the art are also intended. In embodiments, the initiator is included in a conventional amount, such as 0.005% to 0.2% by weight, based on the weight of the polymerizable monomer. In embodiments, the initiator is injected before or into the reaction zone in which free radical polymerization is induced. Termination of catalytic activity can be achieved by a combination of high reactor temperatures for the free radical polymerization portion of the reaction, or by supplying the reactor with an initiator dissolved in a mixture of polar solvents such as propanol, water, or conventional initiator solvents such as branched or unbranched alkanes. In embodiments, the free radical initiator initiates polyethylene chain formation, followed by attack of this propagation chain on the functional groups of f-PDMS (e.g., (meth)acrylate ester groups), followed by further reaction of the newly formed α-carbonyl radical with the ethylene monomer, thus enabling ethylene (either in monomeric or polymeric form) to bond to the (meth)acrylate ester.

[0050] In embodiments, at least one hydrocarbon solvent may be included in the free radical initiator system. The hydrocarbon solvent may be, for example, C5-C 30It may be a hydrocarbon solvent. Exemplary hydrocarbon solvents include, by way of example and not limitation, mineral solvents, normal paraffin solvents, isoparaffin solvents, cyclic solvents, and the like. In an embodiment, the hydrocarbon solvent is selected from the group consisting of n-octane, isooctane (2,2,4-trimethylpentane), n-dodecane, isododecane (2,2,4,6,6-pentamethylheptane), and other isoparaffin solvents. Examples of hydrocarbon solvents such as isoparaffin solvents are commercially available, for example, under the trademarks ISPAR C, ISPAR E, and ISPAR H from ExxonMobil Chemical Co. In an embodiment, the hydrocarbon solvent contains less than 99% by weight of a free radical initiator system.

[0051] An embodiment may further include a polar co-solvent such as an alcohol co-solvent (e.g., C1 - C 30 alcohol), aldehyde, ketone, or ester. The alcohol functional group of the alcohol co-solvent may be monofunctional or polyfunctional. Suitable alcohol co-solvents include, by way of example and not limitation, isopropanol (2-propanol), allyl alcohol, 1-pentanol, methanol, ethanol, propanol, 1-butanol, 1,4-butanediol, combinations thereof, or mixtures thereof. In an embodiment, the polar co-solvent may be included in an amount less than 40% by weight of the free radical initiator system.

[0052] Other additives such as processing aids, plasticizers, stabilizers, UV absorbers, antistatic agents, pigments, dyes, nucleating agents, fillers, slip agents, flame retardants, lubricants, smoke suppressants, viscosity modifiers, antiblocking agents, etc. In an embodiment, one or more of the additives are included in an amount less than 20% by weight of the total weight of the additives, based on the weight of the polymer.

[0053] In embodiments, the process includes a process recycle loop for further improving conversion efficiency. In such embodiments, the downstream reaction region or zone is maintained at a temperature lower than the temperature at which the ethylene polymer phase-separates from the polysiloxane. In embodiments, the recycle loop may be treated to neutralize any residues or by-products from the previous reaction cycle, as such residues or by-products may inhibit the polymerization of either the polysiloxane or the ethylene polymer.

[0054] Ethylene, f-PDMS, initiator, and CTA are each added to the reactor at one or more locations to achieve the desired ratio of components in the feed to and / or within the reaction zone of the reactor. As will be understood by those skilled in the art, the selection of the supply points for each component to the reactor and / or reaction zone depends on several factors, including, but not limited to, the solubility and / or condensation of the components in pressurized ethylene, and / or fouling that may occur in the preheater used to heat the reactor contents before the injection of the initiator.

[0055] The ethylene used for the production of LDPE-co-PDMS may be purified ethylene obtained by removing polar components from a loop recycling stream, or the reaction system configuration may use only fresh ethylene to produce the LDPE-co-PDMS polymer.

[0056] In the embodiment, polymerization is carried out in a continuous stirred-tank reactor using propylene as a chain transfer agent. Ethylene and propylene are supplied to the top of the reactor by a stirrer shaft. In the embodiment, tert-butylperoxyacetate (TPA) and tert-butylperoxyoctoate (TPO) are used as initiators injected into the side of the reactor. In the embodiment, f-PDMS is injected separately into the side of the reactor.

[0057] In further embodiments, the maximum temperature in each reaction zone is 150°C to 360°C, 170°C to 350°C, or 200°C to 325°C. In embodiments, the polymerization pressure at the first inlet of the reactor is 100 MPa to 360 MPa, further 150 MPa to 340 MPa, and further 185 MPa to 320 MPa. After polymerization, the contents of the reactor, including unreacted reactants and the LDPE-co-PDMS polymer, are discharged from the outlet of the reactor.

[0058] The LDPE-co-PDMS polymer can be separated from any remaining reactants according to any method known and used in the art. In embodiments, spraying is used to separate the LDPE-co-PDMS polymer from the remaining reactants, and the LDPE-co-PDMS polymer is collected in powder form.

[0059] While certain LDPE-co-PDMS structures are illustrated in the figures and structures presented herein, other structures are possible and intended to be conceived. Furthermore, in embodiments, the LDPE-co-PDMS polymer is present in a blend containing one or more of the structures shown herein. For example, in embodiments, in addition to the bonding of f-PDMS to LDPE by copolymerizing the functional group double bonds with ethylene, the reaction may also produce a certain amount of byproduct in which LDPE is bonded to PDMS via a chain transfer mechanism through the methyl groups of PDMS. It should also be understood that LDPE-co-PDMS may constitute only a small amount of the reaction product, with the majority of the reaction product being LDPE. In embodiments, LDPE-co-PDMS is present in a blend containing at least one additional polymer. The additional polymers may be, for example, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), very low-density polyethylene (ULDPE), extremely low-density polyethylene (VLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), copolymers containing (meth)acrylate esters, copolymers containing (meth)acrylic acid, monoesters or diesters of maleic acid, copolymers containing vinyl acetate, copolymers containing trialkoxyvinylsilane, grafted polyethylene, or derivatives or combinations thereof.

[0060] In the embodiment, LDPE-co-PDMS may have a polydispersity index (PDI) of 3.0 to 50.0, for example, 5.0 to 45.0, 5.0 to 40.0, 5.0 to 35.0, 5.0 to 30.0, 5.0 to 20.0, or 5.0 to 15.0. In the embodiment, LDPE-co-PDMS may have a melt index (I2) of 0.1 to 500.00 g / 10 min, for example, 0.15 to 100.00 g / 10 min, 0.15 to 25.00 g / 10 min, 0.15 to 10.00 g / 10 min, 0.50 to 10.00 g / 10 min, or 0.50 to 7.50 g / 10 min.

[0061] As those skilled in the art will understand, the elemental composition of the surface of the release liner of the present invention can be determined using X-ray photoelectron spectroscopy ("XPS"). In embodiments disclosed herein, XPS can be used to quantify the amount of silicon on the surface of the release liner formed from the LDPE-co-PDMS polymer as a percentage of the total elemental composition. In embodiments, the atomic percentage or molar percentage of silicon on the surface of the release liner formed from the LDPE-co-PDMS polymer may be 3.00% to 10.00%, for example, 3.00% to 4.00%, 4.00% to 5.00%, 5.00% to 6.00%, 6.00% to 7.00%, 7.00% to 8.00%, 8.00% to 9.00%, or 9.00% to 10.00%.

[0062] Because different downstream applications have different peel force requirements, the peel force of the release liner of the present invention may be determined at various peel rates using procedures that are understood by those skilled in the art. The peel force is the force required to separate the release liner from the pressure-sensitive adhesive. The peel force of the release liner may vary depending on the length over which the release liner is in contact with the pressure-sensitive adhesive. In the embodiments disclosed herein, a release liner comprising an LDPE-co-PDMS polymer may exhibit a peel force of 0.154 Newtons / cm ("N / cm") to 1.35 N / cm, for example, 0.154 N / cm to 0.386 N / cm, 0.386 N / cm to 0.579 N / cm, 0.579 N / cm to 0.772 N / cm, 0.772 N / cm to 0.965 N / cm, 0.965 N / cm to 1.16 N / cm, or 1.16 N / cm to 1.35 N / cm.

[0063] The use of a release liner should not adversely affect the performance of the adhesive. Therefore, to avoid adversely affecting the adhesive strength of the adhesive, the migration of silicone or other types of material from the release liner to the adhesive should be minimized. The subsequent adhesion strength ("SAS") associated with the release liner of the present invention can be evaluated using a procedure that is understood by those skilled in the art. "Adhesion strength" is the force required to remove a unit width of pressure-sensitive tape from a standard stainless steel panel. SAS is the adhesion strength of a "test tape" after contact with the release liner for a given time. The SAS of the test tape is expressed as a percentage of the adhesion strength of the same tape that has not been in contact with the release liner ("fresh tape"), as shown in Equation 1.

[0064]

number

[0065] Equation 1 shows that the greater the influence of the release liner on the adhesive strength of the test tape, the greater the deviation of the test tape's SAS value from 100%. Since the loss of adhesive strength can be due to the migration of silicone from the release liner to the test tape, a higher SAS value indicates less silicone migration. This, in turn, correlates with better release liner performance. In embodiments disclosed herein, the SAS of a pressure-sensitive tape that has been in contact with the release liner of the present invention for a certain period of time may be 70% to 100%, for example, 70% to 80%, 80% to 90%, or 90% to 100%. [Examples]

[0066] Example 1: Synthesis of LDPE-co-PDMS hybrid polymer The LDPE-co-PDMS polymer sample formulations (Table 1, F1-F8) were synthesized as follows: Polymerization was carried out in a 300 mL continuous stirred tank reactor heated to 220 °C using four electric heater bands. The stirrer speed was 1800 revolutions per minute (RPM). The reactor pressure was controlled to approximately 193 MPa. Propylene was used as a chain transfer agent. Ethylene and propylene were supplied to the top of the reactor along the stirrer shaft at a flow rate of 5440–5470 g / h of ethylene. Tert-butyl peroxyacetate ("TPA") and tert-butyl peroxyoctoate ("TPO") were used as initiators in a mass ratio of 0.61:1. The initiators were diluted with ISOPAR E (available from ExxonMobil Chemical Co.) and injected into the side of the reactor at a pressure of 193 MPa at a ratio of 30–33 ppm by mass of TPA and 50–54 ppm by mass of TPO relative to ethylene. For each formulation, the functionalized polysiloxane shown in Table 1 was diluted to 30% by weight with Isopar E and injected into the side of the reactor.

[0067] The residence time in the reactor was approximately 1.5 minutes. All unreacted reactants and polymer were discharged through a single outlet located at the bottom of the reactor. The LDPE-co-PDMS hybrid polymer product was then separated from the remaining reactants by atomization, the flow was reduced to approximately 0.1 MPa, and the flow was simultaneously cooled to ambient temperature. Finally, the LDPE-co-PDMS hybrid polymer was collected in powder form.

[0068] The parameters for each LDPE-co-PDMS polymer sample formulation are shown in Table 1.

[0069] [Table 1]

[0070] Example 2: Analysis of the surface of the release liner To evaluate the mechanical properties of LDPE-co-PDMS hybrid polymers for release liner applications, sample release liners (S1-S8) were prepared from LDPE-co-PDMS polymer formulations 1-8. Release liner sheets from each formulation were prepared by extrusion. The elemental composition of the surface of the sample release liners S1-S8 of the present invention was determined using X-ray photoelectron spectroscopy ("XPS").

[0071] XPS data was acquired using PHI VersaProbe II XPS under the following analysis conditions:

[0072] [Table 2]

[0073] For each sample release liner (S1-S8), a small piece was cut in the center of the sample and attached to a 60 mm platen using double-sided tape. The amount of each element on the surface of each sample was quantified from the integrated peak intensity under specified transitions, according to Equation 1, which describes the instrument-specific cross-sectional area (sensitivity coefficient) of the PHI VersaProbe II spectrometer. Elemental composition was calculated assuming that the detected elements comprised 100% of the species on the surface (note that XPS is insensitive to hydrogen and helium).

[0074]

number

[0075] "C i " is the surface concentration of element i, and "A i " is the integral area of ​​the photoelectron peak of element i, and "S i This is the instrument-dependent sensitivity coefficient for element i.

[0076] The compositional error calculated in this manner stems from two causes: (1) spatial heterogeneity of the sample and (2) measurement error. Spatial heterogeneity is estimated by triplicate measurements. Measurement error is estimated as less than 5% relative + 0.5 × detection threshold of the element in question.

[0077] Table 2 shows the percentage of silicon on the surface of each sample (S1-S8) based on the quantitative determination of silicon 2p electrons.

[0078] [Table 3]

[0079] XPS data confirmed the accumulation of PDMS on the surface of the peel-off liner sample.

[0080] Example 3: Peeling force test Release liner sheets were laminated using Tesa 7475 industrial standard tape (25 mm wide and 200 mm long). The laminated sheets were aged for a period of time under a weight of 20 grams / cm² in a room with controlled temperature (23°C) and controlled humidity (50% relative humidity). The laminated sheets were then cut into strips. The strips were tested in the IMASS ZPE-1100W peel test system at medium to high peel rates (10 m / min, 100 m / min, or 300 m / min) using the 180° peel method. Each sample was tested in triplicate. Table 3 shows the average results for each sample liner of the present invention (S1-S8) at each peel rate after aging for (A) 7 days, (B) 1 month, and (C) 3 months. Table 3 also shows the average results for comparative sample liner 1 (CS1), which contains only LDPE (without PDMS copolymer), at each interlayer delamination rate after aging for (A) 7 days, (B) 1 month, and (C) 3 months.

[0081] [Table 4] * The TT peeling force was too high to perform the test.

[0082] As shown in the data in Table 3, the LDPE liner exhibited a peel force too high to test, and the test tape could not be smoothly separated from the release liner. However, the release liner containing PDMS exhibited dramatically lower peel force values ​​and was able to separate the test tape relatively smoothly from the release liner.

[0083] Example 4: Post-adhesion strength test After the peel test, the Tesa 7475 adhesive tape was peeled off each sample liner and stored. The tape was stacked on a stainless steel test panel by passing a 4.5 lb rotating weight over it four times and left for 20 minutes. The tape on the panel was then tested using a TMI peel / adhesion tester. The adhesive tape was pulled at a 180° angle at 0.3 m / min. For comparative sample 2 (CS2), fresh 7475 tape was subjected to the above method. Each sample was tested in triplicate. The average "post-adhesion strength" ("SAS") for each sample (S1-S8 and CS2) is shown in Table 4.

[0084] [Table 5]

[0085] As mentioned above, a higher SAS value correlates with less loss of adhesive strength due to contact with the release liner, and therefore indicates less silicone migration from the release liner to the tape. Incorporating PDMS into polyethylene resulted in a relatively high SAS, which indicates that silicone migration is well controlled and tape adhesive strength is well maintained, which is important for downstream applications of the tape.

[0086] This disclosure includes several embodiments. A first embodiment is a process for producing a laminated sheet, comprising: applying an uncured adhesive to a removable layer such that a first surface of the removable layer is in direct contact with the uncured adhesive; curing the uncured adhesive to form a cured adhesive layer located in direct contact with the first surface of the removable layer; and applying a release liner in direct contact with the cured adhesive layer such that the cured adhesive layer is located between the removable layer and the release liner, wherein the release liner comprises a copolymer comprising low-density polyethylene and one or more functionalized polysiloxanes, the functionalized polysiloxane being selected from (meth)acrylic acid ester functionalized polysiloxanes and vinyl functionalized polysiloxanes.

[0087] Another embodiment, as enumerated, is the embodiment described in the preceding paragraph, wherein the application of the uncured adhesive to the removable layer is performed as the removable layer moves parallel to the machine direction, the curing of the uncured adhesive is performed as the removable layer moves parallel to the machine direction, and the application of the release liner in direct contact with the cured adhesive layer is performed as the removable layer moves parallel to the machine direction.

[0088] Another embodiment is a process for producing a laminated sheet, comprising: applying an uncured adhesive to a release liner such that a first surface of the release liner is in direct contact with the uncured adhesive; curing the uncured adhesive to form a cured adhesive layer located in direct contact with the first surface of the release liner; and applying a removable layer in direct contact with the cured adhesive layer such that the cured adhesive layer is located between the removable layer and the release liner, wherein the release liner comprises a copolymer comprising low-density polyethylene and one or more functionalized polysiloxanes, the functionalized polysiloxane being selected from (meth)acrylic acid ester functionalized polysiloxanes and vinyl functionalized polysiloxanes.

[0089] Another embodiment is the embodiment described in the preceding paragraph, wherein the application of an uncured adhesive to the release liner is performed as the release liner moves parallel to the machine direction, the curing of the uncured adhesive is performed as the release liner moves parallel to the machine direction, and the application of a removable layer in direct contact with the cured adhesive layer is performed as the release liner moves parallel to the machine direction.

[0090] Another embodiment is any of the aforementioned embodiments in which the release liner has a homogeneous composition.

[0091] Another embodiment is any of the aforementioned embodiments in which the removable layer comprises one or more of the following: paper, vinyl, polyester, polypropylene, foil, and fabric.

[0092] Another embodiment is any of the aforementioned embodiments that does not include the step of applying a silicone liner.

[0093] Another embodiment is any of the aforementioned embodiments in which the curing adhesive is selected from acrylic adhesives, rubber adhesives, hot melt adhesives, water-based adhesives, solvent-based adhesives, pressure-sensitive adhesives, synthetic rubber adhesives, or combinations thereof.

[0094] Another embodiment is any of the aforementioned embodiments in which the uncured adhesive is cured by heat, radiation, or exposure to a catalyst.

[0095] Another embodiment is any of the aforementioned embodiments in which the copolymer further comprises one or more units derived from the termonomer.

[0096] Another embodiment is any of the aforementioned embodiments in which the (meth)acrylic acid ester-functionalized polysiloxane is a (meth)acrylic acid ester-functionalized polydimethylsiloxane, or the vinyl-functionalized polysiloxane is a vinyl-functionalized polydimethylsiloxane, or both.

[0097] Another embodiment is a copolymer with the following structure:

[0098] [ka] Any of the aforementioned embodiments, comprising one or more of the following: (wherein R is methyl or hydrogen, R1 is a crosslinking group that links a functional group ((meth)acrylate) to a siloxane, R2 is a terminal group selected from the group consisting of alkyl, substituted alkyl, aryl, alkenyl, H, and OH, x is an integer from 10 to 1000, y is an integer from 1 to 30, z is any integer from 0 to 30, and y+z is 30 or less).

[0099] Another embodiment involves one or more functionalized polysiloxanes, as follows:

[0100] [ka] Any of the aforementioned embodiments having one or more structural formulas from the following: (wherein R is methyl or hydrogen, R1 is a crosslinking group, R2 is a terminal group selected from alkyl, aryl, alkenyl, H, or OH, x is an integer from 10 to 1000, and y is an integer from 1 to 20).

[0101] The subject matter of this disclosure is described in detail with reference to specific embodiments. Any detailed description of the components or features of the embodiments should be understood not to mean that such components or features are essential to the specific embodiment or any other embodiment. Furthermore, it will be apparent to those skilled in the art that various modifications and changes can be made to the described embodiments without departing from the spirit and scope of the claimed subject matter.

[0102] Note that one or more of the following claims utilize the term “wherein” as a transitional clause. Note that, for the purpose of defining the present invention, this term is introduced into the claims as an unrestricted transitional clause used to introduce an enumeration of a set of structural features and should be interpreted similarly to the more commonly used unrestricted preamble term “comprising.”

Claims

1. A process for producing laminated sheets, The uncured adhesive is applied to the removable layer such that the first surface of the removable layer is in direct contact with the uncured adhesive, The uncured adhesive is cured to form a cured adhesive layer that is in direct contact with the first surface of the removable layer, The process includes applying the release liner in direct contact with the cured adhesive layer such that the cured adhesive layer is located between the removable layer and the release liner, A process wherein the release liner comprises a copolymer containing low-density polyethylene and one or more functionalized polysiloxanes, wherein the functionalized polysiloxane is selected from (meth)acrylic acid ester functionalized polysiloxanes and vinyl functionalized polysiloxanes.

2. The application of the uncured adhesive to the removable layer is performed when the removable layer moves parallel to the machine direction. The curing of the uncured adhesive is performed when the removable layer moves parallel to the machine direction. The process according to claim 1, wherein the release liner is applied in direct contact with the cured adhesive layer as the removable layer moves parallel to the machine.

3. A process for producing laminated sheets, The uncured adhesive is applied to the release liner such that the first surface of the release liner is in direct contact with the uncured adhesive, The uncured adhesive is cured to form a cured adhesive layer that is in direct contact with the first surface of the release liner, The process includes applying the removable layer in direct contact with the cured adhesive layer such that the cured adhesive layer is located between the removable layer and the release liner, A process wherein the release liner comprises a copolymer containing low-density polyethylene and one or more functionalized polysiloxanes, wherein the functionalized polysiloxane is selected from (meth)acrylic acid ester functionalized polysiloxanes and vinyl functionalized polysiloxanes.

4. The application of the uncured adhesive to the release liner is performed when the release liner moves parallel to the machine direction. The curing of the uncured adhesive is performed when the release liner moves parallel to the machine direction. The method according to claim 3, wherein the application of the removable layer in direct contact with the cured adhesive layer is performed when the release liner moves parallel to the machine direction.

5. The process according to any one of claims 1 to 4, wherein the release liner has a homogeneous composition.

6. The process according to any one of claims 1 to 5, wherein the removable layer comprises one or more of the following: paper, vinyl, polyester, polypropylene, foil, and fabric.

7. The process according to any one of claims 1 to 6, wherein the step of applying a silicone liner is not included.

8. The process according to any one of claims 1 to 7, wherein the curing adhesive is selected from acrylic adhesive, rubber adhesive, hot melt adhesive, water-based adhesive, solvent-based adhesive, pressure-sensitive adhesive, synthetic rubber adhesive, or a combination thereof.

9. The process according to any one of claims 1 to 8, wherein the uncured adhesive is cured by heat, radiation, or exposure to a catalyst.

10. The process according to any one of claims 1 to 9, wherein the copolymer further comprises one or more units derived from a termonomer.

11. The (meth)acrylic acid ester-functionalized polysiloxane is a (meth)acrylic acid ester-functionalized polydimethylsiloxane, or The process according to any one of claims 1 to 10, wherein the vinyl-functionalized polysiloxane is one or both of the vinyl-functionalized polydimethylsiloxane.

12. The copolymer has the following structure: 【Chemistry 1】 (In the formula, R is methyl or hydrogen, R １ R is a crosslinking group that links a functional group ((meth)acrylate) to a siloxane, ２ The process according to any one of claims 1 to 11, wherein x is a terminal group selected from the group consisting of alkyl, substituted alkyl, aryl, alkenyl, H, and OH, x is an integer from 10 to 1000, y is an integer from 1 to 30, z is any integer from 0 to 30, and y + z is 30 or less.

13. One or more functionalized polysiloxanes, as follows: 【Chemistry 2】 (In the formula, R is methyl or hydrogen, R １ is a crosslinking group, R ２ The process according to any one of claims 1 to 12, wherein x is a terminal group selected from alkyl, aryl, alkenyl, H, or OH, x is an integer from 10 to 1000, and y is an integer from 1 to 20.

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