Electrically debondable UV-activated adhesives

Abstract

Curable compositions and cured compositions, as well as articles comprising the curable or cured compositions, are provided. The cured composition is typically a semi-structural or structural adhesive. Advantageously, the cured composition may be removed (e.g., debonded) from various surfaces of an article after its useful life to correct misalignment of parts during manufacturing, or repair electronic devices. The separation step is carried out using a DC potential across the cured composition.

Description

Background Art

[0001] New adhesives are needed for the manufacture of electronic devices and various industrial applications. For example, in electronic devices, particularly mobile electronic devices (e.g., handheld or wearable electronic devices), various adhesives (such as pressure sensitive adhesives) are used to bond the cover glass (or lens) to the display module below, the touch sensor to the cover glass and the display, or the lower component of the display to the housing. The selected adhesive should generally have a sufficiently high bond strength to properly maintain good adhesion to those components not only when the mobile electronic devices are operating in normal conditions, but also when they are subjected to traumatic forces (e.g., when being impacted and / or dropped onto a hard surface).

[0002] In addition, electronic devices need new adhesives that can perform well during the useful life of the device, but can be removed (e.g., debonded) from the electronic components after the useful life of the device or to repair the device to extend the useful life of the device. The removal of the adhesive is preferably clean so that the electronic components can be reused or recycled, or so that the electronic device can be repaired. Summary of the invention

[0003] Provided are curable compositions and cured compositions, and articles comprising the curable compositions and cured compositions. The function of the curable compositions is usually similar to a pressure-sensitive adhesive, and the cured compositions are usually semi-structural or structural adhesives. The cured compositions can be used in various articles of electronics, transportation and construction industries, with a surface attached to another surface. For example, the cured compositions can be used in mobile electronic devices where bonding parts are required to have impact resistance and / or drop resistance, or where one of the components is glass and another component is attached to various articles on a glass surface.

[0004] Advantageously, the cured composition can be removed (e.g., debonded) from various surfaces of the article after the useful life of the article to correct misalignment of parts during manufacturing, or to repair electronic devices. For example, the cured composition can be removed, allowing various components that were attached together to be reused in the manufacture of new articles, or to correct manufacturing errors. This is of great value to manufacturers of electronic devices because it allows expensive electronic components to be reused. In addition, for situations where different materials are ideally separated into different waste streams, end-of-life recyclability can be improved.

[0005] In a first aspect, a curable composition is provided. The curable composition contains (a) a (meth) acrylic multi-block copolymer, (b) a statistical (meth) acrylic copolymer, (c) an epoxy resin, (d) a photoacid generator, and (e) an ionic liquid having a melting point of less than 100 degrees Celsius and having a selected from SbF6- PF6 - or a mixture thereof.

[0006] In a second aspect, a first article is provided. The first article comprises (a) a curable composition as described above in the first aspect and (b) a first substrate or a first release liner positioned adjacent to a first surface of the curable composition.

[0007] In a third aspect, a cured composition is provided, wherein the cured composition is a reaction product of the curable composition described in the first aspect.

[0008] In a fourth aspect, a second article is provided. The second article comprises (a) a first substrate, (b) a second substrate, and (c) the cured composition of the third aspect positioned between the first substrate and the second substrate, wherein the cured composition bonds the first substrate to the second substrate.

[0009] In a fifth aspect, a method for manufacturing the second article described in the fourth aspect is provided. The method comprises preparing a curable composition as described in the first aspect above, wherein the curable composition has a first surface positioned adjacent to a release liner. The method further comprises positioning a second substrate adjacent to a second surface of the curable composition opposite to the first surface. The method further comprises removing the release liner from the first surface of the curable composition. The method further comprises exposing a layer of the curable composition to ultraviolet radiation. The method further comprises positioning a layer of the first substrate adjacent to the curable composition relative to the second substrate, and curing the curable layer to bond the first substrate to the second substrate. In some embodiments, at least one of the first substrate or the second substrate is conductive.

[0010] In a sixth aspect, a method for separating the second article described in the fourth aspect is provided. The method comprises applying a DC potential across the cured composition to separate the first substrate from the second substrate. Preferably, at least one of the first substrate or the second substrate is conductive.

[0011] The terms "a", "an", "the", and "said" are used interchangeably, wherein "at least one" means one or more of the elements. The phrases "at least one of" and "comprising at least one of" followed by a list refer to any one of the items in the list and any combination of two or more of the items in the list.

[0012] The term "and / or" means either or both. For example, the expression X and / or Y means X, Y, or a combination thereof (both X and Y).

[0013] The term "curable" refers to a composition or component that can be cured. The terms "cured" and "curing" refer to the joining of polymer chains together by covalent chemical bonds to form a polymer network. The cured polymer network is generally characterized by insolubility, but it may be swellable in the presence of an appropriate solvent.

[0014] As used herein, the term "resin component" refers to the material remaining after deducting any inorganic materials that may be present from the curable composition. As used herein, the resin component includes, but is not limited to, (meth)acrylic multi-block copolymers, statistical (meth)acrylic copolymers, syrup compositions containing polymer materials dissolved in various monomers, poly(alkylene oxide) (meth)acrylates, monomers, epoxy resins, polyols, photoacid generators, and ionic liquids that are fluid below 100 degrees Celsius.

[0015] The term "curable composition" refers to the total reaction mixture that is subjected to curing. The curable composition comprises a resin component and any optional inorganic materials. The term "cured composition" refers to the cured reaction product of the curable composition.

[0016] The term "polymerizable component" refers to a compound that can undergo free radical polymerization (i.e., the compound has a polymerizable group). The polymerizable component typically has an ethylenically unsaturated group, such as a (meth)acryloyl-containing group or a vinyl group that is a polymerizable group. The polymerizable component is interchangeably referred to as a "monomer". The term "macromer" refers to a monomer that has a polymerizable group, such as a polyether group (i.e., a macromonomer is a subset of monomers).

[0017] The term "polymerizable composition" refers to a reaction mixture that can be polymerized by free radical polymerization. It contains polymerizable components (i.e., monomers including unimolecular monomers) and any other materials that can be included in the reaction mixture, such as free radical initiators, chain transfer agents, antioxidants, solvents, etc.

[0018] The term "(meth)acryloyl" refers to a radical of the formula CH2=CR-(C=O)-, wherein R is hydrogen (for an acryloyl radical) or methyl (for a methacryloyl radical).

[0019] The term "(meth)acrylate" refers to methacrylate and / or acrylate. Likewise, the term "(meth)acrylic acid" refers to methacrylic acid and / or acrylic acid, and the term "(meth)acrylamide" refers to methacrylamide and / or acrylamide.

[0020] The term "(meth)acrylic acid" refers to compounds having a (meth)acryloyl group of the formula H2C=CR-(CO)-, wherein R is hydrogen or methyl. These compounds may be monomers, including macromonomers, or polymers.

[0021] The term "(meth)acrylic" refers to a polymer formed from at least 50 wt% (meth)acrylic acid-containing monomers, based on the total weight of the monomers. In some embodiments, the (meth)acrylic polymer is formed from at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, at least 97 wt%, at least 98 wt%, at least 99 wt%, or even 100 wt% (meth)acrylic acid-containing monomers.

[0022] The term "monomer unit" refers to the reaction product of polymerizable components (i.e., monomers (including macromers)) within a polymer material. For example, the monomer unit of acrylic acid (H2C=CH-(C=O)-OH) is

[0023]

[0024] Where an asterisk (*) indicates a site of attachment to another group, such as another monomer unit in a polymer.

[0025] The term "poly(alkylene oxide) group" refers to a group having a plurality of alkylene oxide units. The alkylene oxide units are typically selected from ethylene oxide, propylene oxide, tetrahydrofuran oxide or mixtures thereof.

[0026] The terms "polymer" and "polymeric material" refer to homopolymers, copolymers, terpolymers, etc. As used herein, the term "copolymer" is used herein to refer to any polymer prepared from two or more different monomers.

[0027] The term "statistical" with respect to (meth)acrylic copolymers refers to copolymers formed from a polymerizable composition having multiple different types of monomers. Under some conditions, statistical (meth)acrylic copolymers are random copolymers. However, under other conditions, (meth)acrylate copolymers may not be completely random because differences in the concentration and reactivity of the monomers may create conditions in which the early stages of polymerization may favor the polymerization of one type of monomer in the polymerizable composition. The terms "statistical" and "random" are often used interchangeably in polymer publications. If the terms "block" or "multiblock" do not appear in the description (i.e., name) of a copolymer, it is presumed to be a statistical copolymer.

[0028] The term "glass transition temperature" may be abbreviated as "T g ", refers to the temperature at which a polymer material transitions from a glassy state to a molten or rubbery state. This test is typically performed using a rheometer as described in the "Examples" section.

[0029] As used herein, the term "semi-structural adhesive" refers to those cured compositions having a lap shear strength of at least 0.60 megapascals (MPa) or at least 0.75 MPa. More preferably, the lap shear strength is at least 1.0 MPa or at least 1.5 MPa. However, those cured compositions having particularly high lap shear strengths are referred to herein as "structural adhesives." Structural adhesives are those cured compositions having a lap shear strength of at least 3.5 MPa, at least 4 MPa, at least 5 MPa, at least 6 MPa, or at least 7 MPa.

[0030] As used herein, any description of a range includes the endpoints of the range and all appropriate values ​​within that range (eg, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0031] As used herein, the term "room temperature" refers to a temperature of 20 degrees Celsius to 30 degrees Celsius, such as 20 degrees Celsius to 25 degrees Celsius, 22 degrees Celsius to 25 degrees Celsius, or 23 degrees Celsius.

[0032] The terms "in the range" or "within a range" (and similar expressions) include the endpoints of the range. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1A is a schematic side view of an exemplary article of the present application;

[0034] Figure 1B for Figure 1A A schematic side view of a variation of the article in;

[0035] Figure 1C for Figure 1A A schematic side view of another variation of the article in;

[0036] Figure 2A is a schematic side view of another exemplary article of the present application;

[0037] Figure 2B for Figure 2A A schematic side view of a variation of the article in; and

[0038] Figure 3 is a diagram of a test setup for tensile extrusion testing. DETAILED DESCRIPTION

[0039] The present invention provides a curable composition that can be cured to form a cured composition suitable for use in electronic devices and various industrial applications. The curable composition generally functions similarly to a pressure sensitive adhesive, and the cured composition is generally a semi-structural or structural adhesive. The cured composition can be formed by exposing the curable composition to ultraviolet radiation.

[0040] The cured composition often has sufficient tensile strength and shear impact resistance to be used in applications where impact resistance and drop resistance are required. Another desirable property of the cured composition is that it can be separated (e.g., debonded) from a substrate (e.g., a component of an article) to which it is attached by applying a DC potential. This property allows, for example, the reuse of expensive components in new articles, the repair of articles, and / or the recycling of various components that were previously bonded together.

[0041] Curable composition

[0042] A curable composition is provided which can be cured by exposure to ultraviolet radiation to form a cured composition, which is typically positioned between and bonded to two different substrates. If at least one of the substrates is conductive or can be made conductive, the cured composition can then be debonded from one or both substrates using a direct current potential. The curable composition typically contains a film-forming polymeric material, an epoxy resin, a photoactivated generator, and an ionic liquid.

[0043] In some embodiments of the curable composition, the film-forming polymer material includes two different (meth) acrylic polymer materials, such as a (meth) acrylic multi-block copolymer and a statistical (meth) acrylic copolymer. In such embodiments, the curable composition curable composition generally contains (a) a (meth) acrylic multi-block copolymer, (b) a statistical (meth) acrylic copolymer, (c) an epoxy resin, (d) a photoactivated generator, and (e) an ionic liquid. The statistical (meth) acrylic copolymer is generally formed in the presence of a (meth) acrylic multi-block copolymer, but may also be formed in the presence of other materials in the curable composition. Each component of the curable composition is further described below.

[0044] (Meth)acrylic multi-block copolymer

[0045] The curable composition includes a (meth) acrylic multi-block copolymer. The term "multi-block copolymer" refers to a copolymer having a plurality of different polymer segments (referred to as "blocks"). Each block may be a homopolymer (i.e., a polymer segment formed by a single type of monomer) or a copolymer (i.e., a polymer segment formed by a plurality of (i.e., two or more) different types of monomers). The boundary between adjacent blocks in a block copolymer may be sharp (i.e., the composition of the monomer units changes suddenly at the boundary between the two blocks) or tapered (i.e., the composition of the monomer units does not change suddenly at the boundary between the two blocks, but is mixed in the transition region near the boundary; the transition region includes monomer units from two adjacent blocks).

[0046] The term "triblock copolymer" refers to a multi-block copolymer having three different polymer blocks, and the term "diblock copolymer" refers to a multi-block copolymer having two different polymer blocks. Both triblock copolymers and diblock copolymers contain polymer blocks arranged in a linear manner relative to each other. In other words, diblock copolymers and triblock copolymers are not star copolymers, graft copolymers, comb copolymers, dendrimers, or other macromolecules having a substantially nonlinear structure.

[0047] In most embodiments, the (meth) acrylic multi-block copolymer is a triblock copolymer. However, in some embodiments, the curable composition comprises both a triblock copolymer and a diblock copolymer. The multi-block copolymer is usually formed mainly by a (meth) acrylic monomer having a group H2C=CR-(CO)- (wherein R is hydrogen or methyl). (Meth) acrylic monomers include (meth) acrylate monomers, (meth) acrylic acid monomers, (meth) acrylamide monomers and mixtures thereof. Typically, at least 80% by weight or more of the monomer units in the multi-block copolymer are from (meth) acrylic monomers. For example, at least 85% by weight, at least 90% by weight, at least 95% by weight, at least 97% by weight, at least 98% by weight, at least 99% by weight or 100% by weight of the monomers used to form the (meth) acrylic multi-block copolymer are (meth) acrylic monomers. In some embodiments, the monomers are all (meth) acrylic ester monomers.

[0048] The triblock usually has an ABA structure, wherein the A block and the B block are selected to have sufficiently different solubility parameters to cause phase separation between the A block and the B block. In order to produce this phase separation, two A blocks and one B block in the (meth) acrylic triblock copolymer ABA are usually selected to have different glass transition temperatures. The A block usually has a higher glass transition temperature than the B block, and can be referred to as a "hard" block, while the B block can be referred to as a "soft" block. The A block is usually selected to have a greater rigidity than the B block. The A block can be thermoplastic, and can provide semi-structural or structural strength and / or shear strength to the adhesive composition. The B block can be a viscous material, and can provide viscosity and bonding strength to the adhesive composition.

[0049] The A block of the (meth)acrylic triblock copolymer ABA is generally selected to have a glass transition temperature (T) equal to at least 50° C. when measured using dynamic mechanical analysis. g). In some embodiments, the glass transition temperature is at least 60°C, at least 70°C, at least 75°C, at least 80°C, at least 90°C, or at least 100°C. The glass transition temperature can be up to 200°C, up to 190°C, up to 180°C, up to 175°C, up to 170°C, up to 160°C, up to 150°C, up to 140°C, up to 130°C, up to 125°C, up to 120°C, up to 110°C, or up to 100°C. Exemplary ranges of the glass transition temperature of the A block include 50°C to 200°C, 75°C to 200°C, 70°C to 175°C, 75°C to 150°C, or 80°C to 140°C.

[0050] The B block of the (meth) acrylic triblock copolymer ABA is a sticky segment and is generally selected to have a glass transition temperature of no more than 20°C when measured using dynamic mechanical analysis. In some embodiments, the glass transition temperature is no more than 10°C, no more than 5°C, no more than 0°C, no more than -10°C, no more than -20°C, or no more than -30°C. The glass transition temperature is generally at least -70°C, at least -60°C, at least -50°C, at least -40°C, or at least -30°C, depending on the composition of the monomers used to form the B block. Exemplary ranges of the glass transition temperature of the B block include -70°C to 20°C, -70°C to 10°C, -70°C to 0°C, -50°C to 0°C, -70°C to -10°C, -50°C to -10°C, -70°C to -20°C, -50°C to -20°C, -70°C to -30°C, or -50°C to -30°C.

[0051] The (meth)acrylic triblock copolymer ABA has two polymer A blocks and one polymer B block. Each of these blocks can be a homopolymer or a copolymer (e.g., a statistical copolymer). The (meth)acrylic triblock copolymer ABA typically comprises 10 to 55% by weight of A blocks and 45 to 90% by weight of B blocks, based on the total weight of the (meth)acrylic triblock copolymer. The (meth)acrylic triblock copolymer comprises at least 10%, at least 20%, at least 25%, at least 30%, or at least 35% by weight and up to 55%, up to 50%, up to 45%, up to 40%, or up to 35% by weight of A blocks, based on the total weight of the (meth)acrylic triblock copolymer. The (meth)acrylic triblock copolymer comprises at least 45 wt%, at least 50 wt%, at least 55 wt%, or at least 60 wt%, and up to 90 wt%, up to 80 wt%, up to 75 wt%, up to 70 wt%, up to 65 wt%, or up to 60 wt% of B blocks, based on the total weight of the (meth)acrylic triblock copolymer. The sum of the weight percentage of the A block and the weight percentage of the B block approaches 100 wt% based on the total weight of the (meth)acrylic triblock copolymer (i.e., a small amount of initiator residues may also be present). In some examples, the (meth)acrylic block copolymer contains 15 wt % to 55 wt % A blocks and 45 wt % to 85 wt % B blocks, 15 wt % to 40 wt % A blocks and 60 wt % to 85 wt % B blocks, 20 wt % to 55 wt % A blocks and 45 wt % to 80 wt % B blocks, 20 wt % to 40 wt % A blocks and 60 wt % to 80 wt % B blocks, or 20 wt % to 35 wt % A blocks and 65 wt % to 80 wt % B blocks.

[0052] The two A blocks of the (meth)acrylic triblock copolymer ABA can each have approximately the same weight. That is, the weight ratio of the two A blocks of the (meth)acrylic triblock copolymer is often 1:1 or close to 1:1 (e.g., greater than 0.9:1). However, other weight ratios may also be used, such as in the range of 0.65:1 to 0.99:1. In many cases, the weight ratio of the two A blocks of the (meth)acrylic triblock copolymer is not less than 0.65:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1, 0.98:1, or 0.99:1.

[0053] Each A block of the (meth)acrylic triblock copolymer ABA is typically prepared from a monomer composition comprising an alkyl methacrylate. Alkyl methacrylates suitable for preparing the A blocks typically have an alkyl group having 1 to 10 carbon atoms, 1 to 8 carbon atoms, 1 to 6 carbon atoms, 1 to 5 carbon atoms, or 1 to 4 carbon atoms. If the alkyl group has 3 to 5 carbon atoms, it is typically branched. If the alkyl group has 6 to 10 carbon atoms, it is typically cyclic or bicyclic.

[0054] Exemplary alkyl methacrylates include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, methylcyclohexyl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate, and isobornyl methacrylate. These monomers have a glass transition temperature equal to at least 50° C. when polymerized as a homopolymer.

[0055] In some cases, the A block is a homopolymer, and each homopolymer is a poly(alkyl methacrylate). Exemplary poly(alkyl methacrylates) include poly(methyl methacrylate), poly(ethyl methacrylate), poly(isopropyl methacrylate), poly(isobutyl methacrylate), poly(sec-butyl methacrylate), poly(tert-butyl methacrylate), poly(cyclohexyl methacrylate), poly(methylcyclohexyl methacrylate), poly(3,3,5-trimethylcyclohexyl methacrylate), and poly(isobornyl methacrylate).

[0056] In addition to the alkyl methacrylate monomer, the first monomer composition for forming the first A block may include other optional monomers, provided that the resulting polymer block has a glass transition temperature equal to at least 50°C when measured using dynamic mechanical analysis. In some embodiments, the first monomer composition may include other (meth) acrylic monomers, such as alkoxy-substituted alkyl methacrylates, aryl methacrylates, aryl methacrylates, aryloxy-substituted alkyl methacrylates, cyclic alkyl acrylates with cyclic groups containing 6 to 10 carbon atoms, bicyclic alkyl acrylates with bicyclic alkyl groups containing at least 8 carbon atoms, or mixtures thereof. Suitable alkoxy-substituted alkyl methacrylates often have alkyl groups containing 1 to 4 carbon atoms and alkoxy groups containing 1 to 4 carbon atoms. An example is 2-methoxyethyl methacrylate. Suitable aryl methacrylates generally have aryl groups containing 6 to 10 carbon atoms. Exemplary aryl methacrylates are phenyl methacrylates. Suitable aryl methacrylates generally have aryl alkyl groups containing 7 to 10 carbon atoms. An exemplary aralkyl methacrylate is phenyl methacrylate. Suitable aryloxy-substituted alkyl methacrylates typically have an aryloxy-substituted alkyl group containing 7 to 10 carbon atoms. An exemplary aryloxy-substituted alkyl methacrylate is 2-phenoxyethyl methacrylate. An exemplary cyclic alkyl acrylate is cyclohexyl acrylate, and an exemplary dicyclic acrylate is isobornyl acrylate.

[0057] In other embodiments, the first monomer composition for forming the A block may include various optional (meth) acrylic polar monomers, provided that the glass transition temperature of each resulting block is equal to at least 50°C. These polar monomers, if present, are typically present in an amount not exceeding 10 wt%, not exceeding 5 wt%, not exceeding 2 wt%, or not exceeding 1 wt% based on the total weight of the monomers in the corresponding monomer composition. Suitable polar monomers include, for example, hydroxyl groups or glycidyl groups. Typically, acidic monomers and nitrogen-containing monomers are not selected (for example, the first monomer composition is typically free of such monomers). Specific monomers include, but are not limited to, hydroxyalkyl (meth) acrylates, such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and glycidyl (meth) acrylate. However, in many embodiments, there are no polar monomers in the A block.

[0058] In other embodiments, the first monomer composition used to form the A block may include other optional monomers other than (meth)acrylic monomers, provided that greater than 80% by weight of the monomers in the block are (meth)acrylic monomers and the resulting polymer block has a glass transition temperature equal to at least 50° C. when measured using dynamic mechanical analysis. Exemplary of these other monomers are vinyl monomers such as styrene, styrenic monomers (e.g., α-methylstyrene, 3-methylstyrene, 4-methylstyrene, ethylstyrene, isopropylstyrene, tert-butylstyrene, dimethylstyrene, 2,4,6-trimethylstyrene, and 4-methoxystyrene), and vinyl acetate.

[0059] The A blocks of the (meth)acrylic triblock copolymers are often homopolymers formed from alkyl methacrylates, and the resulting polymer blocks have a glass transition temperature equal to at least 50° C. when measured using dynamic mechanical analysis. In some specific embodiments, the two A blocks are the same homopolymer, being poly(alkyl methacrylate). In some more specific embodiments, these A blocks are poly(methyl methacrylate).

[0060] The B block of the (meth)acrylic triblock copolymer ABA is typically formed from monomers that will provide a polymer block having a glass transition temperature of no more than 20°C when measured using dynamic mechanical analysis. The B block is typically prepared from a monomer composition comprising an alkyl acrylate. In other words, the B block is a polymer material formed from a second monomer composition comprising an alkyl acrylate. Alkyl acrylates suitable for forming the B block often have an alkyl group containing 2 to 20, 2 to 18, 2 to 12, or 2 to 10 carbon atoms. The alkyl group can be linear, branched, cyclic, or a combination thereof (e.g., the alkyl group can have a cyclic group plus a branched or linear group).

[0061] Specific examples of alkyl acrylate monomers that can be used to form the B block include, but are not limited to, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, n-pentyl acrylate, isopentyl acrylate, n-hexyl acrylate, 2-methylbutyl acrylate, 4-methyl-2-pentyl acrylate, cyclohexyl acrylate, 2-methylhexyl acrylate, n-octyl acrylate, 2-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, n-decyl acrylate, isodecyl acrylate, lauryl acrylate, isotridecyl acrylate, isostearyl acrylate, and octadecyl acrylate. Many of these monomers have a glass transition temperature of no more than 20° C. when polymerized to form a homopolymer as measured using dynamic mechanical analysis.

[0062] In some cases, the B block is a homopolymer. Examples of homopolymers include, but are not limited to, poly(ethyl acrylate), poly(n-propyl acrylate), poly(n-butyl acrylate), poly(isobutyl acrylate), poly(sec-butyl acrylate), poly(isoamyl acrylate), poly(n-hexyl acrylate), poly(2-methylbutyl acrylate), poly(4-methyl-2-pentyl acrylate), poly(cyclohexyl acrylate), poly(2-methylhexyl acrylate), poly(n-octyl acrylate), poly(2-octyl acrylate), poly(isooctyl acrylate), poly(2-ethylhexyl acrylate), poly(isononyl acrylate), poly(n-decyl acrylate), poly(isodecyl acrylate), poly(lauryl acrylate), poly(isotridecyl acrylate), poly(isostearyl acrylate), and poly(octadecyl acrylate). In some more specific cases, the B block is poly(n-butyl acrylate), poly(n-octyl acrylate), poly(2-octyl acrylate), poly(isooctyl acrylate), poly(2-ethylhexyl acrylate), or poly(isononyl acrylate). In some even more specific cases, the B block is poly(n-butyl acrylate).

[0063] The second monomer composition used to form the B block may further comprise optional monomers in addition to the alkyl acrylate monomers, provided that the resulting polymer block has a glass transition temperature of no greater than 20° C. when measured using dynamic mechanical analysis.

[0064] In some embodiments, the second monomer composition for forming the B block may optionally include (meth) acrylate heteroalkyl esters, acrylate arylalkyl esters, aryloxy-substituted alkyl acrylates, or methacrylate alkyl esters with a straight or branched alkyl group containing at least 6 carbon atoms. Suitable acrylate heteroalkyl esters include, but are not limited to (meth) 2-ethoxyethyl acrylate, 2-methoxyethyl acrylate, and 2-(2-ethoxyethoxy)ethyl acrylate. Suitable acrylate arylalkyl esters include, but are not limited to, 2-bisphenylhexyl acrylate and benzyl acrylate. Exemplary aryloxy-substituted alkyl acrylates are 2-phenoxyethyl acrylate. Suitable methacrylate alkyl esters are n-decyl methacrylate, lauryl methacrylate, n-octyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, and n-hexyl methacrylate.

[0065] In other embodiments, the second monomer composition for forming the B block may include various (meth) acrylic polar monomers, provided that the glass transition temperature of these blocks does not exceed 20°C when measured using dynamic mechanical analysis. These polar monomers, if present, are typically present in an amount of no more than 10 wt%, no more than 5 wt%, no more than 2 wt%, or no more than 1 wt% based on the total weight of the monomers in the corresponding monomer composition. Suitable polar monomers include, for example, hydroxy-substituted (meth) alkyl acrylates. Polar monomers are typically not acidic monomers and nitrogen-containing monomers (e.g., the second monomer composition is typically free of such monomers). Specific polar monomers include, but are not limited to, (meth) acrylic acid, 2-hydroxyethyl (meth) acrylate, and 2-hydroxypropyl (meth) acrylate. However, in many embodiments, there are no polar monomers in the B block.

[0066] The B block of the (meth)acrylic triblock copolymer is often a homopolymer formed from an alkyl acrylate, and the resulting polymer block has a glass transition temperature of no more than 20° C. when measured using dynamic mechanical analysis. In some specific embodiments, the B block is a poly(alkyl acrylate). In some more specific embodiments, the B block is poly(n-butyl acrylate), poly(n-octyl acrylate), poly(2-octyl acrylate), poly(isooctyl acrylate), poly(2-ethylhexyl acrylate), or poly(isononyl acrylate).

[0067] In some (meth)acrylic triblock copolymers, each A block comprises monomer units derived from methyl methacrylate, and the B blocks comprise monomer units derived from n-butyl (meth)acrylate, such as n-butyl acrylate.

[0068] The weight average molecular weight (M) of the (meth)acrylic triblock copolymer ABA w ) is typically at least 25 kilodaltons (kDa), at least 30 kDa, at least 35 kDa, at least 40 kDa, at least 45 kDa, or at least 50 kDa, and is at most 200 kDa, at most 190 kDa, at most 180 kDa, at most 175 kDa, at most 170 kDa, at most 160 kDa, at most 150 kDa, at most 140 kDa, at most 130 kDa, at most 125 kDa, at most 120 kDa, at most 115 kDa, at most 110 kDa, at most 100 kDa, at most 90 kDa, at most 80 kDa, or at most 75 kDa. The weight average molecular weight is typically in the range of 50 kDa to 200 kDa, 50 kDa to 175 kDa, or 50 kDa to 150 kDa. Weight average molecular weight is typically determined using gel permeation chromatography with polystyrene standards.

[0069] (Meth) acrylic triblock copolymers can be synthesized using any suitable technique. Suitable techniques may include, for example, anionic polymerization, free radical polymerization, group transfer polymerization, and ring-opening polymerization. The polymerization may be "living" or "controlled / living" polymerization, which may advantageously produce a strictly defined block copolymer structure. Specific synthetic methods include atom transfer radical polymerization (ATRP) processes and reversible addition-fragmentation chain transfer polymerization (RAFT) processes. Such processes are disclosed in, for example, U.S. Patents 7,255,920 (Everaerts et al.), 6,734,256 (Everaerts et al.), and 6,806,320 (Everaerts et al.). Other synthetic methods include the use of controlled radical initiators, which are bisdithiocarbamate or bisdithiocarbonate compounds, such as those disclosed in U.S. Pat. Nos. 10,400,055 (Griesgraber et al.), 10,640,686 (Roscoe et al.), and 10,913,807 (Yurt et al.) and U.S. Patent Application Publication No. 2021 / 0095097 (Lewandowski et al.).

[0070] Living polymerization can also provide block copolymers with sharp transitions between blocks. Block copolymers with A blocks and B blocks can have regions near the block boundaries that contain a mixture of A monomer units and B monomer units. When using living polymerization techniques, the size of such regions can be minimized or even eliminated, resulting in a more dramatic transition from A blocks to B blocks. This may be advantageous when phase separation is desired, because the region of mixed monomer units can be compatible with both blocks, thereby reducing phase separation. On the other hand, a sharp transition with a minimal region of mixed monomer units can promote phase separation.

[0071] Suitable commercially available (meth)acrylic triblock copolymers are available from Kuraray Co., Ltd. (Tokyo, Japan) under the trade name "KURARITY". These copolymers include, for example, KURARITY LA2330, L3320, and LA2250. Other suitable commercially available (meth)acrylic triblock copolymers are available from Arkema (Colombes, France) under the trade name "NANOSTRENGTH". These copolymers include, for example, NANOSTRENGTH M51, M52, M53, M55, M65, and M75.

[0072] The curable composition generally includes 10% to 40% by weight of (meth) acrylic multi-block copolymers based on the total weight of the resin component in the curable composition. The amount can be at least 10% by weight, at least 12% by weight, at least 15% by weight, at least 20% by weight, at least 25% by weight or at least 30% by weight, and is at most 40% by weight, at most 35% by weight, at most 30% by weight or at most 25% by weight. The amount is generally in the range of 10% to 40% by weight, 10% to 35% by weight, 10% to 30% by weight, 10% to 25% by weight, 15% to 40% by weight, 15% to 35% by weight, 15% to 30% by weight, 15% to 25% by weight, 20% to 40% by weight, 20% to 35% by weight or 25% to 40% by weight.

[0073] In addition to the triblock copolymer, the curable composition may also optionally include a (meth) acrylic diblock copolymer. The diblock copolymer (which may be referred to as a CD diblock copolymer) generally includes the following C block: the C block may be prepared from the same monomers as those suitable for forming the A block in the triblock copolymer. In addition, the D block of the diblock copolymer may be prepared from the same monomers as those suitable for forming the B block in the triblock copolymer. If the diblock copolymer is used in combination with the triblock copolymer, the A block and the C block are generally formed from the same monomers, while the B block and the D block are generally formed from the same monomers.

[0074] The (meth) acrylic diblock copolymer generally comprises 5 to 30 wt% of C blocks and 70 to 95 wt% of D blocks. The amount of C blocks may be at least 5 wt%, at least 10 wt%, at least 15 wt%, or at least 20 wt%, and at most 30 wt%, at most 25 wt%, at most 20 wt%, or at most 15 wt%, based on the total weight of the diblock copolymer. The amount of D blocks may be at least 70 wt%, at least 75 wt%, at least 80 wt%, at least 85 wt%, and at most 95 wt%, at most 90 wt%, at most 85 wt%, or at most 80 wt%. The sum of the amounts of C blocks and D blocks is equal to (or close to) 100 wt% due to the presence of a small amount of initiator residues.

[0075] The weight average molecular weight of the (meth)acrylic diblock is typically in the range of 30 kDa to 150 kDa. The weight average molecular weight is typically at least 30 kDa, at least 40 kDa, at least 50 kDa, at least 60 kDa, at least 70 kDa, at least 80 kDa, at least 90 kDa, or at least 100 kDa, and at most 150 kDa, at most 140 kDa, at most 130 kDa, at most 120 kDa, at most 110 kDa, at most 100 kDa, at most 90 kDa, or at most 80 kDa. The weight average molecular weight can be determined by gel permeation chromatography using polystyrene standards.

[0076] The curable composition typically includes 0 to 30 wt % of the optional (meth) acrylic diblock copolymer based on the total weight of the resin component in the curable composition. If present, the amount may be at least 5 wt %, at least 10 wt %, at least 15 wt %, or at least 20 wt %, and at most 30 wt %, at most 25 wt %, at most 20 wt %, at most 15 wt %, or at most 10 wt %. In many embodiments, the curable composition does not include the optional (meth) acrylic diblock copolymer.

[0077] Statistical (meth)acrylic acid copolymer

[0078] The curable composition also comprises a statistical (meth)acrylic copolymer. Although there are a variety of methods for preparing statistical (meth)acrylic copolymers, such copolymers are typically formed in the presence of a (meth)acrylic block copolymer. That is, the (meth)acrylic block copolymer is dissolved in a monomer composition to form a slurry. Prior to polymerization of the monomers in the slurry, the slurry may optionally be combined with one or more other components of the curable composition.

[0079] Statistical (meth)acrylic copolymers are generally formed from a polymerizable composition containing one or more alkyl (meth)acrylate monomers, an optional (meth)acrylic macromonomer having a poly(alkylene oxide) group, and one or more optional polar monomers. Since other components of the curable composition, such as epoxy resins, may be present when forming the statistical (meth)acrylic copolymer, the optional polar monomers are generally selected to not contain groups that can react with epoxy resins at or near room temperature (e.g., 20 degrees Celsius to 25 degrees Celsius).

[0080] The polymerizable composition for forming the statistical (meth)acrylic copolymer comprises one or more alkyl (meth)acrylate monomers. Any suitable alkyl (meth)acrylate or mixture of alkyl (meth)acrylates may be included in the polymerizable composition. The selection of alkyl (meth)acrylate can affect the glass transition temperature of the statistical (meth)acrylic copolymer. Typically, the monomers are selected so that the glass transition temperature of the statistical (meth)acrylic copolymer does not exceed 20 degrees Celsius. For example, the glass transition temperature is typically no more than 15 degrees Celsius, no more than 10 degrees Celsius, no more than 5 degrees Celsius, or no more than 0 degrees Celsius.

[0081] Some alkyl (meth)acrylate monomers are classified as low T based on the glass transition temperature of their corresponding homopolymers. g Monomer. Low T measured from the corresponding homopolymer g The monomers generally have a T of no greater than 20°C, no greater than 10°C, no greater than 0°C, or no greater than -10°C. g Other alkyl (meth)acrylates are classified as high T based on the glass transition temperature of the corresponding homopolymer. g Monomer. High T measured from the corresponding homopolymer g The monomers typically have a T greater than 30°C, greater than 40°C, or greater than 50°C. g The glass transition temperature can be measured using dynamic mechanical analysis (DMA) as described in the Examples section.

[0082] Suitable low T g The alkyl (meth)acrylate monomer includes, but is not limited to, non-tertiary alkyl acrylate, but may be an alkyl (meth)acrylate having a linear alkyl group containing at least 4 carbon atoms. Specific examples of alkyl (meth)acrylates include, but are not limited to, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, sec-butyl acrylate, n-pentyl acrylate, 2-methylbutyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, 4-methyl-2-pentyl acrylate, 2-methylhexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, 2-octyl acrylate, isooctyl acrylate, isononyl acrylate, isopentyl acrylate, and combinations thereof. The alkyl (meth)acrylate monomer is typically selected to include at least one low T g Monomers, such as T when measured as homopolymers g Those not greater than -10° C. Such alkyl monomers include, but are not limited to, 2-ethylhexyl acrylate, isooctyl acrylate, n-butyl acrylate, 2-methylbutyl acrylate, isooctyl acrylate, 2-octyl acrylate, and combinations thereof.

[0083] Some suitable high T gThe alkyl (meth)acrylate monomers include, for example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, stearyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, and combinations thereof.

[0084] Typically, the alkyl (meth)acrylate is selected to have an alkyl group of no more than 8 carbon atoms, no more than 7 carbon atoms, no more than 6 carbon atoms, no more than 5 carbon atoms, or no more than 4 carbon atoms to enhance the compatibility of the statistical (meth)acrylic copolymer with the other components of the curable composition.

[0085] The total amount of alkyl (meth)acrylates can be any amount up to 30 wt% to 100 wt%, based on the total weight of the monomers in the (meth)acrylic polymerizable composition used to form the statistical (meth)acrylic copolymer. The amount of alkyl (meth)acrylate can be, for example, at least 30 wt%, at least 35 wt%, at least 40 wt%, at least 45 wt%, or at least 50 wt%, and up to 100 wt%, up to 99 wt%, up to 98 wt%, up to 97 wt%, up to 95 wt%, up to 92 wt%, up to 90 wt%, up to 85 wt%, or up to 80 wt%.

[0086] Statistical (meth)acrylic copolymers are typically prepared from a polymerizable composition that also includes a (meth)acrylic monomer (i.e., macromer) having a poly(alkylene oxide) group. Such monomers, which may be referred to as "(meth)acrylate macromers," typically have a number average molecular weight of at least 300 Daltons (Da). The poly(alkylene oxide) group is typically poly(ethylene oxide), poly(propylene oxide), poly(tetramethylene oxide), or copolymers thereof. The terms "poly(tetramethylene oxide)" and "poly(tetrahydrofuran)" are used interchangeably.

[0087] The (meth)acrylate macromers typically have the formula (I).

[0088] CH2=CR 2 -(C=O)-O-(R 3 -O) p -R 4

[0089] (I)

[0090] In formula (I), the group R 2is hydrogen or methyl. 3 is independently an alkylene group having 2 to 4 carbon atoms, R 4 is an alkyl group having 1 to 4 carbon atoms. The variable p ranges from 5 to 150. For example, the variable n is at least 5, at least 10, at least 20, at least 30, at least 40, or at least 50, and at most 150, at most 125, at most 100, at most 90, at most 80, at most 70, at most 60, at most 50, at most 40, or at most 30. The group -(R 3 -O) p -R 4 Typically it is a poly(tetramethylene oxide), poly(propylene oxide), poly(propylene oxide)-co-poly(ethylene oxide), or poly(ethylene oxide) group.

[0091] The number average molecular weight of the (meth)acrylate macromonomer with poly(alkylene oxide) side groups is typically at least 300 Daltons (Da) or 400 Da. Although the number average molecular weight can be as high as 10,000 Da, it is typically up to 5000 Da or 4000 Da. The number average molecular weight can be at least 300 Da, at least 400 Da, at least 500 Da, at least 600 Da, at least 800 Da, at least 1000 Da, at least 1200 Da, or at least 1500 Da, and at most 10,000 Da, at most 5000 Da, at most 4500 Da, at most 4000 Da, at most 3500 Da, at most 3000 Da, at most 2500 Da, at most 2000 Da, at most 1500 Da, or at most 1000 Da. If the number average molecular weight is greater than 5000 Da, the (meth)acrylate macromonomer may crystallize depending on its composition. If the number average molecular weight is less than 300 Da, the impact resistance of the cured product may be poor.

[0092] The (meth)acrylate macromonomer is typically selected to be non-waxy at room temperature. That is, a (meth)acrylate macromonomer is selected that is non-crystalline and liquid at room temperature. The (meth)acrylate macromonomer typically has a glass transition temperature of no greater than -20°C (as measured using a homopolymer of the macromonomer). For example, the glass transition temperature may be no greater than -30°C, no greater than -40°C, no greater than -50°C, or no greater than -60°C. The low glass transition temperature of such a macromonomer imparts conformability and flexibility to the statistical (meth)acrylic copolymer and the adhesive composition containing the statistical (meth)acrylic copolymer.

[0093] Examples of such commercially available (meth)acrylate macromonomers can be obtained from Millipore Sigma (Burlington, Massachusetts, USA), including poly(ethylene glycol) phenyl ether acrylate having a number average molecular weight of 324 Da, methoxypolyethylene glycol 550 acrylate (MPEG550A) having a number average molecular weight of 550 Da, poly(ethylene glycol) methyl ether acrylate having a number average molecular weight of 480 Da, poly(ethylene glycol) methyl ether acrylate having a number average molecular weight of 2,000 Da, poly(ethylene glycol) methyl ether acrylate having a number average molecular weight of 5,000 Da, and poly(propylene glycol) acrylate having a number average molecular weight of 475 Da.

[0094] Other suitable (meth)acrylate macromonomers are available from Geo Specialty Chemicals, Ambler, PA, under the tradename BISOMER, such as BISOMER PPA6 (poly(propylene glycol) acrylate having a reported number average molecular weight of 420 Daltons), BISOMER PEM63P HD (a mixture of poly(ethylene glycol) methacrylate and poly(propylene glycol) having a reported number average molecular weight of 524 Daltons), BISOMER PPM5 LI (poly(propylene glycol) methacrylate having a reported number average molecular weight of 376 Daltons), BISOMER PEM6 LD (poly(ethylene glycol) methacrylate having a reported number average molecular weight of 350 Daltons), BISOMER MPEG350MA (methoxy poly(ethylene glycol) methacrylate having a reported number average molecular weight of 430 Daltons), and BISOMER MPEG550MA (methoxy poly(ethylene glycol) methacrylate having a reported number average molecular weight of 628 Daltons). Other suitable (meth)acrylate macromonomers are available from Miwon Specialty Chemical Company, Gyeonggi-do, Korea, under the trade designation MIRAMER, such as MIRAMER M193 MPEG600MA (methoxy poly(ethylene glycol) methacrylate having a reported number average molecular weight of 668 daltons), MIRAMER M164 (nonylphenol poly(ethylene glycol) acrylate having a reported number average molecular weight of 450 daltons), MIRAMER M1602 (nonylphenol poly(ethylene glycol) acrylate having a reported number average molecular weight of 390 daltons), and MIRAMER M166 (nonylphenol poly(ethylene glycol) acrylate having a reported number average molecular weight of 626 daltons). Still other suitable (meth)acrylate macromers are commercially available from Sans Esters Corporation, New York, NY, such as MPEG-A400 (methoxy poly(ethylene glycol) acrylate having a reported number average molecular weight of 400 Daltons) and MPEG-A550 (methoxy poly(ethylene glycol) acrylate having a reported number average molecular weight of 550 Daltons). Various combinations of such macromers may be used if desired.

[0095] In many embodiments, the polymerizable composition for forming the statistical (meth) acrylic copolymer contains 0 wt % to 40 wt % of (meth) acrylate macromonomers. When exposed to radiation suitable for curing, the macromonomers tend to increase the open time of the curable composition. Long open time provides more time to position the curable composition adjacent to the desired substrate before a significant amount of curing occurs. If present, the amount is typically at least 1 wt %, at least 2 wt %, at least 3 wt %, at least 4 wt %, at least 5 wt %, at least 10 wt %, at least 15 wt % or at least 20 wt %, and is at most 40 wt %, at most 35 wt %, at most 30 wt %, at most 25 wt %, at most 20 wt %, at most 15 wt % or at most 10 wt %, based on the total weight of the polymerizable composition for forming the statistical (meth) acrylic copolymer. The amount can range, for example, from 4 wt % to 40 wt %, 5 wt % to 40 wt %, 5 wt % to 35 wt %, 5 wt % to 30 wt %, 5 wt % to 25 wt %, 5 wt % to 20 wt %, or 5 wt % to 15 wt % of the (meth)acrylate macromer.

[0096] In addition to the (meth) alkyl acrylate and the optional (meth) acrylate macromer, the polymerizable composition for forming the statistical (meth) acrylic copolymer optionally contains a polar monomer. The polar monomer comprises an ethylenically unsaturated group plus a polar group. The ethylenically unsaturated group is a vinyl or (meth) acryloyl group. Suitable polar groups can be hydroxyl groups, ether (or polyether) groups, or epoxy groups. Polar monomers are generally not acidic monomers because these monomers tend to react with epoxy resins in the curable composition. In addition, due to the reactivity of these groups with epoxy resins, polar monomers are generally not nitrogen-containing monomers. That is, the polymerizable composition for forming the statistical (meth) acrylic copolymer does not contain acidic polar monomers, or contains less than 0.5% by weight, less than 0.2% by weight, less than 0.1% by weight, less than 0.05% by weight, less than 0.02% by weight, or less than 0.01% by weight of acidic polar monomers based on the total weight of the polymerizable composition. Additionally, the polymerizable composition used to form the statistical (meth)acrylic copolymer contains no nitrogen-containing polar monomers, or contains less than 0.5 wt%, less than 0.2 wt%, less than 0.1 wt%, less than 0.05 wt%, less than 0.02 wt%, or less than 0.01 wt% of nitrogen-containing polar monomers based on the total weight of the polymerizable composition.

[0097] Exemplary polar monomers having a hydroxyl group include, but are not limited to, hydroxyalkyl (meth)acrylates (e.g., 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate), ethoxylated hydroxyethyl (meth)acrylate, and aryloxy-substituted hydroxyalkyl (meth)acrylates (e.g., 2-hydroxy-2-phenoxypropyl (meth)acrylate).

[0098] Exemplary ether-containing polar monomers include those selected from 2-ethoxyethoxyethyl (meth)acrylate, 2-methoxyethoxyethyl (meth)acrylate, di(ethylene glycol)-2-ethylhexyl ether acrylate, ethylene glycol-methyl ether acrylate, and combinations thereof. Suitable ether-containing (meth)acrylate monomers typically have a number average molecular weight of less than 300 Daltons, less than 275 Daltons, or less than 250 Daltons.

[0099] The amount of any non-acidic and non-nitrogen-containing polar monomer in the polymerizable composition used to form the statistical (meth)acrylic copolymer can range from 0 wt% to 30 wt%, based on the total weight of the monomers in the polymerizable composition. The amount can be 0 wt%, at least 0.5 wt%, at least 1 wt%, at least 2 wt%, at least 3 wt%, at least 5 wt%, at least 10 wt%, or at least 15 wt%, and up to 30 wt%, up to 25 wt%, up to 20 wt%, up to 15 wt%, up to 10 wt%, or up to 5 wt%, based on the total weight of the monomers in the polymerizable composition.

[0100] A crosslinking monomer may optionally (but typically) be included in the polymerizable composition. The crosslinking monomer typically comprises a plurality of polymerizable (meth)acryloyl groups (e.g., 2, 3, or 4 (meth)acryloyl groups). That is, the crosslinking monomer is typically a multifunctional (meth)acrylate monomer. Crosslinking the statistical (meth)acrylic copolymer may contribute to the dimensional stability of the curable composition.

[0101] Examples of crosslinking monomers having two (meth)acryloyl groups include, but are not limited to, glycerol di(meth)acrylate, hexanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,3-propylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,4-cyclohexanediol di(meth)acrylate, urethane di(meth)acrylate, and polyethylene glycol di(meth)acrylate. Examples of crosslinking monomers having three (meth)acryloyl groups include, but are not limited to, glycerol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, 1,2,4-butanetriol tri(meth)acrylate, and pentaerythritol tri(meth)acrylate. Examples of crosslinking monomers having four or more (meth)acryloyl groups include, but are not limited to, pentaerythritol tetra(meth)acrylate, sorbitol hexa(meth)acrylate.

[0102] The polymerizable composition can include 0 wt % to 5 wt % of a crosslinking monomer. If present, the amount can be at least 0.01 wt %, at least 0.05 wt %, at least 0.1 wt %, at least 0.2 wt %, at least 0.3 wt %, at least 0.5 wt %, or at least 1 wt %, and up to 5 wt %, up to 4 wt %, up to 3 wt %, up to 2 wt %, or up to 1 wt %, based on the total weight of the polymerizable components in the polymerizable composition.

[0103] The polymerizable composition used to form the statistical (meth)acrylic copolymer typically comprises 0 to 40 wt% (meth)acrylate macromonomer, 30 to 100 wt% alkyl (meth)acrylate, and 0 to 30 wt% non-acidic and non-nitrogen-free polar monomer (e.g., the polar monomer is typically a hydroxyl-containing monomer), based on the total weight of the monomers in the polymerizable composition. In some examples, the polymerizable composition used to form the statistical (meth)acrylic copolymer comprises 3 to 40 wt% (meth)acrylate macromonomer, 30 to 97 wt% alkyl (meth)acrylate, and 0 to 30 wt% non-acidic and non-nitrogen-free polar monomer (e.g., the polar monomer is typically a hydroxyl-containing monomer), based on the total weight of the monomers in the polymerizable composition. In other examples, the polymerizable composition contains 5 to 30 weight percent (meth) acrylate macromonomers, 50 to 95 weight percent (meth) alkyl acrylates, and 0 to 20 weight percent non-acidic and non-nitrogen-free polar monomers. In other examples, the polymerizable composition contains 5 to 25 weight percent (meth) acrylate macromonomers, 60 to 90 weight percent (meth) alkyl acrylates, and 0 to 20 weight percent non-acidic and non-nitrogen-free polar monomers. Any of these polymerizable compositions may further contain 0 to 5 weight percent crosslinking monomers.

[0104] In addition to the monomers (eg, alkyl (meth)acrylate and optional monomers), the polymerizable composition typically includes a free radical initiator. In many embodiments, the free radical initiator can be a thermal initiator or a photoinitiator.

[0105] Suitable thermal initiators include various azo compounds such as those commercially available under the trade name VAZO from The Chemours Co. (Wilmington, DE, USA), including VAZO 67 (which is 2,2'-azobis(2-methylbutyronitrile)), VAZO 64 (which is 2,2'-azobis(isobutyronitrile)), VAZO 52 (which is 2,2'-azobis(2,4-dimethylvaleronitrile)), and VAZO 88 (which is 1,1'-azobis(cyclohexanecarbonitrile)); various peroxides such as benzoyl peroxide, cyclohexane peroxide, lauroyl peroxide, di-tert-amyl peroxide, t-butyl perbenzoate, dicumyl peroxide, and the like under the trade name LUPERSOL from Atofina Chemical Co. (Philadelphia, PA, USA). Inc. (Philadelphia, PA, USA)); various hydroperoxides, such as tert-amyl hydroperoxide and tert-butyl hydroperoxide; and mixtures thereof.

[0106] In many embodiments, a photoinitiator is used to form the statistical (meth)acrylic copolymer. Although any photoinitiator can be used in the polymerization reaction to form the statistical (meth)acrylic copolymer if no epoxy resin is present during the polymerization reaction, if an epoxy resin is present, the photoinitiator is generally selected to be activated by a wavelength greater than 380 nanometers or at least 400 nanometers.

[0107] Some exemplary photoinitiators are benzoin ethers (e.g., benzoin methyl ether or benzoin isopropyl ether) or substituted benzoin ethers (e.g., anisole methyl ether). Other exemplary photoinitiators are substituted acetophenones, such as 2,2-diethoxyacetophenone or 2,2-dimethoxy-2-phenylacetophenone (commercially available under the trade name IRGACURE 651 from BASF Corp., Florham Park, NJ, USA or under the trade name ESACURE KB-1 from Sartomer, Exton, PA, USA). Still other exemplary photoinitiators are substituted α-keto alcohols (such as 2-methyl-2-hydroxypropiophenone), aromatic sulfonyl chlorides (such as 2-naphthalenesulfonyl chloride), and photoactive oximes (such as 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)oxime). Other suitable photoinitiators include, for example, 1-hydroxycyclohexyl phenyl ketone (commercially available under the trade name IRGACURE 184), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (commercially available under the trade name IRGACURE 819), 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one (commercially available under the trade name IRGACURE 2959), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone (commercially available under the trade name IRGACURE 369), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (commercially available under the trade name IRGACURE 907), and 2-hydroxy-2-methyl-1-phenylpropan-1-one (commercially available under the trade name DAROCUR 1173 from Ciba Specialty Chemicals, Tarrytown, New York, USA).

[0108] Other free radical photoinitiators are acylphosphine oxides, such as those described in US Pat. No. 4,737,593 (Ellrich et al.) These acylphosphine oxides are generally of formula (III) or (IV).

[0109]

[0110] In formulae (III) and (IV), each R 5Independently be the straight chain or branched alkyl with 1 to 18 carbon atoms, the cycloalkyl with 5 to 6 ring members (that is, cyclopentyl and cyclohexyl), the cycloalkyl of replacement, aryl (for example, phenyl, biphenyl and naphthyl), the aryl of replacement, or have 5 or 6 ring members and have one or more sulfur, nitrogen or oxygen heteroatoms heterocycle.Suitable substituents of the aryl of replacement and the cycloalkyl group of replacement include halogen group (for example, F, Cl, Br and I), alkyl group (for example, there is 1 to 10 carbon atoms, 1 to 6 carbon atoms or 1 to 4 carbon atoms alkyl group) or alkoxy group (for example, there is 1 to 10 carbon atoms, 1 to 6 carbon atoms or 1 to 4 carbon atoms alkoxy group).

[0111] Each R in formula (III) and (IV) 6 Independently be cycloalkyl (i.e., cyclopentyl and cyclohexyl), substituted cycloalkyl, aryl (e.g., phenyl, biphenyl and naphthyl), substituted aryl with 5 to 6 ring members, or heterocycle with one or more sulfur, nitrogen or oxygen heteroatoms and 5 or 6 ring members. Suitable substituents for substituted aryl and substituted cycloalkyl groups include halogen groups (e.g., F, Cl, Br and I), alkyl groups (e.g., alkyl groups with 1 to 10 carbon atoms, 1 to 6 carbon atoms or 1 to 4 carbon atoms) or alkoxy groups (e.g., alkoxy groups with 1 to 10 carbon atoms, 1 to 6 carbon atoms or 1 to 4 carbon atoms). The group R in formula (III) 6 and R 7 They may combine to form a ring containing 4 to 10 carbon atoms, which may be optionally substituted with one or more alkyl groups (eg, 1 to 6 alkyl groups).

[0112] In some embodiments, the acylphosphine has the formula (III), wherein R 5 is an aryl group, R 6 is an aryl group substituted by an alkyl group or an alkoxy group, and R 7 is an aryl group substituted with an alkyl or alkoxy group. In some specific embodiments, the acylphosphine is bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, which is commercially available under the trade name IRGACURE 819 from Ciba Specialty Chemicals.

[0113] In other embodiments, the acryloylphosphine has the formula (IV) wherein each R 5 is any aromatic group, and R 6is an aryl group substituted by an alkyl group or an alkoxy group. For example, the acylphosphine can be diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, which is commercially available under the trade name TPO from Millipore Sigma (formerly Sigma Aldrich), St. Louis, MO, USA.

[0114] In other embodiments, the acylphosphine has the formula (IV) wherein the first R 5 is an aryl group, the second R 5 is an alkyl group, and R 6 is an aryl group substituted by an alkyl group. For example, the acylphosphine may be ethyl (2,4,6-trimethylbenzoyl)phenylphosphinate, which is commercially available under the trade name TPO-L from Lambson, Wetherby, West Yorkshire, England.

[0115] The amount of free radical initiator can affect the molecular weight of the statistical (meth) acrylic copolymer, wherein a larger amount of free radical initiator generally produces a polymer of lower molecular weight. The amount of initiator is generally in the range of 0.01 wt % to 5 wt % based on the total weight of the polymerizable components in the polymerizable composition. The amount can be at least 0.01 wt %, at least 0.05 wt %, at least 0.1 wt %, at least 0.2 wt %, at least 0.5 wt % or at least 1 wt %, and at most 5 wt %, at most 4 wt %, at most 3 wt %, at most 2 wt %, at most 1 wt % or at most 0.5 wt %.

[0116] Chain transfer agents can optionally be included in the polymerizable composition to control the molecular weight of the statistical (meth) acrylic copolymer. Suitable chain transfer agents include, but are not limited to, those selected from the following: carbon tetrabromide, hexabromoethane, bromotrichloromethane, 2-mercaptoethanol, tert-dodecyl mercaptan, isooctylthioglycolate, 3-mercapto-1,2-propylene glycol, cumene, pentaerythritol tetrakis (3-mercaptobutyrate) (available under the trade name KARENZ MT PE1 from Showa Denko), ethylene glycol dithioglycolate, and mixtures thereof. Depending on the reactivity of the selected chain transfer agent, the amount of the chain transfer agent is typically in the range of 0 wt % to 5 wt % based on the total weight of the monomers in the polymerizable composition. In some embodiments, the amount of chain transfer agent is at least 0.05 wt%, at least 0.1 wt%, at least 0.2 wt%, at least 0.3 wt%, or at least 0.5 wt%, and can be up to 5 wt%, up to 4.5 wt%, up to 4 wt%, up to 3.5 wt%, up to 3 wt%, up to 2.5 wt%, up to 2 wt%, up to 1.5 wt%, or up to 1 wt%. These weight percentage values ​​are based on the total weight of the polymerizable components in the polymerizable composition used to form the statistical (meth)acrylic copolymer.

[0117] The curable composition generally comprises 20% to 60% by weight of a statistical (meth) acrylic copolymer based on the total weight of the resin component in the curable composition. The amount may be at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, or at least 45%, and at most 60%, at most 55%, at most 50%, at most 45%, or at most 40%. For example, the amount may be in the range of 20% to 50%, 25% to 60%, 25% to 50%, 30% to 60%, 30% to 50%, or 40% to 60%.

[0118] Epoxy resin

[0119] The curable composition includes an epoxy resin having at least one epoxy functional group (ie, oxirane group) per molecule. As used herein, the term oxirane group refers to the following divalent group.

[0120]

[0121] The asterisk represents the point at which the oxirane group is attached to another group. If the oxirane group is in the terminal position of the epoxy resin, the oxirane group is typically bonded to a hydrogen atom.

[0122]

[0123] The terminal oxirane group is typically (and preferably) part of a glycidyl group.

[0124]

[0125] Although epoxy resins may have a single oxirane group per molecule, they typically have at least two oxirane groups per molecule. For example, epoxy resins may have 1 to 10, 2 to 10, 2 to 6, 2 to 4, or 2 oxirane groups per molecule. Oxirane groups are typically part of a glycidyl group.

[0126] The epoxy resin may be a single material or a mixture of different materials selected to provide the desired viscosity characteristics before curing and the desired mechanical properties after curing. If the epoxy resin is a mixture of materials, at least one of the epoxy resins in the mixture is typically selected to have at least two oxirane groups per molecule. For example, the first epoxy resin in the mixture may have two to four oxirane groups, and the second epoxy resin in the mixture may have one to four oxirane groups. In some of these examples, the first epoxy resin is a first glycidyl ether having two to four glycidyl groups, and the second epoxy resin is a second glycidyl ether having one to four glycidyl groups. In another example, the first epoxy resin in the mixture is a liquid, and the second epoxy resin is a solid, such as a glassy or brittle solid miscible with the first epoxy resin.

[0127] The portion of the epoxy resin molecule that is not an oxirane group (i.e., the epoxy resin molecule minus the oxirane group) may be aromatic, aliphatic, or a combination thereof, and may be linear, branched, cyclic, or a combination thereof. The aromatic and aliphatic portions of the epoxy resin may contain heteroatoms or other groups that do not react with the oxirane group. That is, the epoxy resin may include halogen groups, such as oxygen groups in ether bond groups, carbonyl groups, carbonyloxy groups, and the like. The epoxy resin may also be a silicone-based material, such as a polydiorganosiloxane-based material.

[0128] In most embodiments, the epoxy resin comprises a glycidyl ether. An exemplary glycidyl ether may have formula (V).

[0129]

[0130] In formula (V), the group R 1 is a p-valent group of aromatic, aliphatic or a combination thereof. 1 It can be linear, branched, cyclic or a combination thereof. 1Optionally include halogen groups, oxy groups, carbonyl groups, carbonyloxy groups, etc. Although the variable p can be any suitable integer greater than or equal to 1, p is typically an integer in the range of 2 to 6 or 2 to 4. In many embodiments, p is equal to 2.

[0131] In some exemplary epoxy resins of formula (V), the variable p is equal to 2 (ie, the epoxy resin is a diglycidyl ether), and R 1 Includes alkylene (i.e., alkylene is a divalent radical of an alkane and can be referred to as an alkane-diyl), heteroalkylene (i.e., heteroalkylene is a divalent radical of a heteroalkane and can be referred to as a heteroalkane-diyl), arylene (i.e., a divalent radical of an aromatic compound), or mixtures thereof. Suitable alkylene groups typically have 1 to 20 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Suitable heteroalkylene groups typically have 2 to 50 carbon atoms, 2 to 40 carbon atoms, 2 to 30 carbon atoms, 2 to 20 carbon atoms, 2 to 10 carbon atoms, or 2 to 6 carbon atoms. The heteroatoms in heteroalkylene are typically oxy groups. Suitable arylene groups typically have 6 to 18 carbon atoms, 6 to 12 carbon atoms, or 6 to 10 carbon atoms. For example, arylene can be phenylene. The group R 1 A halogen group, an oxy group, a carbonyl group, a carbonyloxy group, etc. may also be optionally included.

[0132] Some epoxy resins of formula (V) are diglycidyl ethers, wherein R 1 The group R includes (a) an arylene group or (b) an arylene group in combination with an alkylene group, a heteroalkylene group, or both. 1 Optional groups may also be included, such as halogen groups, oxy groups, carbonyl groups, carbonyloxy groups, etc. These epoxy resins may be prepared, for example, by reacting an aromatic compound having at least two hydroxyl groups with an excess of epichlorohydrin. Examples of useful aromatic compounds having at least two hydroxyl groups include, but are not limited to, resorcinol, catechol, hydroquinone, p,p'-dihydroxydibenzyl, p,p'-dihydroxyphenyl sulfone, p,p'-dihydroxybenzophenone, 2,2'-dihydroxyphenyl sulfone, and p,p'-dihydroxybenzophenone. Other examples include the 2,2′, 2,3′, 2,4′, 3,3′, 3,4′, and 4,4′ isomers of dihydroxydiphenylmethane, dihydroxydiphenyldimethylmethane, dihydroxydiphenylethylmethylmethane, dihydroxydiphenylmethylpropylmethane, dihydroxydiphenylethylphenylmethane, dihydroxydiphenylpropylphenylmethane, dihydroxydiphenylbutylphenylmethane, dihydroxydiphenyltolylethane, dihydroxydiphenyltolylmethylmethane, dihydroxydiphenyldicyclohexylmethane, and dihydroxydiphenylcyclohexane.

[0133] Some commercially available diglycidyl ether epoxy resins of formula (V) are derived from bisphenol A (i.e., bisphenol A is 4,4'-dihydroxydiphenylmethane). Examples include, but are not limited to, those available from Hexion Specialty Chemicals, Inc. (Houston, TX) under the trade name EPON (e.g., EPON 828, EPON 872, EPON 1001F, EPON 1004, and EPON 2004), those available from Olin Epoxy (Clayton, MO, USA) under the trade name DER (e.g., DER 331, DER 332, and DER 336), and those available from Dainippon Ink and Chemicals, Inc. (Chiba, Japan) under the trade name EPICLON (e.g., EPICLON 850). Other commercially available diglycidyl ether epoxy resins are derived from bisphenol F (ie, bisphenol F is 2,2'-dihydroxydiphenylmethane).

[0134] Other epoxy resins of formula (V) are diglycidyl ethers of poly(alkylene oxide) glycols. These epoxy resins may be referred to as diglycidyl ethers of poly(alkylene glycol) glycols. The variable p is equal to 2, and R 4 For heteroalkylene with oxygen heteroatoms. Poly(alkylene glycol) may be a copolymer or a homopolymer. Examples include, but are not limited to, diglycidyl esters of poly(ethylene oxide) glycol, diglycidyl esters of poly(propylene oxide) glycol, and diglycidyl esters of poly(tetramethylene oxide) glycol. This type of epoxy resin is commercially available from Polysciences, Inc., Warrington, PA, USA, such as those derived from poly(ethylene oxide) glycol or those derived from poly(propylene oxide) glycol, with a weight average molecular weight of about 400 Daltons, about 600 Daltons, or about 1000 Daltons. Other aliphatic epoxy resins of this type can be commercially available from Nagase Industries Co., Ltd. (Nagase & Co., LTD (Osaka, Japan)) in Osaka, Japan under the trade name DENACOL (e.g., DENACOL Ex-830).

[0135] Other epoxy resins of formula (V) are diglycidyl ethers of alkanediols (R 1is an alkylene group and the variable p is equal to 2). Examples include the diglycidyl ether of 1,4-dimethanol cyclohexyl, the diglycidyl ether of 1,4-butanediol, and the diglycidyl ethers of cycloaliphatic diols formed from hydrogenated bisphenol A, such as those commercially available under the trade name EPONEX 1510 from Hexion Specialty Chemicals, Houston, Texas, USA.

[0136] Other epoxy resins include silicone resins having at least two glycidyl groups and flame retardant epoxy resins having at least two glycidyl groups (e.g., brominated bisphenol-type epoxy resins having at least two glycidyl groups, such as commercially available under the trade name DER 580 from The Dow Chemical Company, Midland, Michigan, USA).

[0137] Epoxy resins are typically mixtures of materials. For example, epoxy resins may be selected to provide a mixture of desired viscosity or flow characteristics prior to curing. The mixture may include at least one first epoxy resin referred to as a reactive diluent with a lower viscosity and at least one second epoxy resin with a higher viscosity. Reactive diluents tend to reduce the viscosity of epoxy resin mixtures and typically have a saturated branched backbone or a saturated or unsaturated cyclic backbone. Examples include, but are not limited to, diglycidyl ethers of resorcinol, diglycidyl ethers of cyclohexanedimethanol, diglycidyl ethers of neopentyl glycol, and triglycidyl ethers of trimethylolpropane. The diglycidyl ether of cyclohexanedimethanol is commercially available from Hexion Specialty Chemicals (Columbus, OH, USA) under the trade name HELOXYMODIFIER 107 and from Evonik Corporation (Essen, North Rhine-Westphalia, Germany) under the trade name EPODIL 757. Other reactive diluents have only one functional group (i.e., an oxirane group), such as various monoglycidyl ethers. Some exemplary monoglycidyl ethers include, but are not limited to, alkyl glycidyl ethers in which the alkyl group has 1 to 20 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Some exemplary monoglycidyl ethers are commercially available from Evonik Corporation under the trade designation EPODIL, such as EPODIL 746 (2-ethylhexyl glycidyl ether) and EPODIL 748 (aliphatic glycidyl ether).

[0138] Epoxy resin has the equivalent weight in the range of 50 g / equivalent to 750 g / equivalent usually.The equivalent weight of epoxy resin refers to the weight of the resin in grams containing an equivalent of epoxide.Equivalent weight is usually not more than 750 g / equivalent, not more than 700 g / equivalent, not more than 650 g / equivalent, not more than 600 g / equivalent, not more than 550 g / equivalent, not more than 500 g / equivalent, not more than 450 g / equivalent, not more than 400 g / equivalent, not more than 350 g / equivalent, not more than 300 g / equivalent or not more than 250 g / equivalent, and is usually at least 50 g / equivalent, at least 75 g / equivalent, at least 100 g / equivalent, at least 125 g / equivalent or at least 150 g / equivalent. In some embodiments, the equivalent weight is generally in the range of 50 g / equivalent to 750 g / equivalent, 50 g / equivalent to 500 g / equivalent, 100 g / equivalent to 500 g / equivalent, 100 g / equivalent to 300 g / equivalent, or 150 g / equivalent to 250 g / equivalent.

[0139] In many embodiments, 100% by weight of the epoxy resin has formula (I). In other embodiments, at least 95%, at least 90%, at least 85%, at least 80%, at least 75%, or at least 70% by weight of the epoxy resin has formula (I).

[0140] In many embodiments, 100% by weight of the epoxy resin is a diglycidyl ether (i.e., a compound of formula (I) with p equal to 2). In other embodiments, the epoxy resin is a mixture of a compound of formula (I) with p equal to 2 and a compound of formula (I) with p not equal to 2. In such a mixture, the amount of diglycidyl ether is typically at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% by weight, based on the total weight of the epoxy resin.

[0141] In most embodiments, the epoxy resin contains no compounds having oxirane groups that are not glycidyl groups. However, if such compounds are included, they typically constitute less than 30 weight percent, less than 20 weight percent, less than 10 weight percent, less than 5 weight percent, less than 2 weight percent, less than 1 weight percent, or less than 0.5 weight percent based on the total weight of the epoxy resin.

[0142] Curable composition generally comprises the epoxy resin of 10 % by weight to 50 % by weight based on the total weight of resin component in this curable composition.This amount can be at least 10 % by weight, at least 15 % by weight, at least 20 % by weight, at least 25 % by weight or at least 30 % by weight, and at most 50 % by weight, at most 45 % by weight, at most 40 % by weight, at most 35 % by weight, or at most 30 % by weight.For example, this amount can be in the scope of 10 % by weight to 45 % by weight, 10 % by weight to 40 % by weight, 15 % by weight to 50 % by weight, 15 % by weight to 45 % by weight, 15 % by weight to 40 % by weight, 20 % by weight to 50 % by weight, 20 % by weight to 45 % by weight or 20 % by weight to 40 % by weight based on the total weight of resin component in this curable composition.

[0143] Photoacid generator

[0144] The photoacid generator (also referred to as a cationic photoinitiator) is activated to initiate polymerization of the epoxy resin in the curable composition. It is typically selected to be sensitive to (activated by) radiation in the ultraviolet region of the electromagnetic spectrum. For example, the photoacid generator is typically selected to be activated at a wavelength of less than or equal to 380 nanometers in the ultraviolet region of the electromagnetic spectrum.

[0145] Some suitable photoacid generators are aryl-containing (eg, bis(aryl-containing)) iodonium salts. Exemplary aryl-containing iodonium salts are iodonium salts having two aryl groups, such as iodonium bis(4-tert-butylphenyl)hexafluoroantimonate (available under the trade name FP5034 from Hampford Research Inc. (Stratford, CT, USA)), iodonium bis(4-tert-butylphenyl)camphorsulfonate, iodonium bis(4-tert-butylphenyl)hexafluorophosphate, iodonium bis(4-tert-butylphenyl)tetraphenylborate, iodonium bis(4-tert-butylphenyl)toluenesulfonate, iodonium bis(4-tert-butylphenyl)trifluoromethanesulfonate, iodonium (4-methoxyphenyl)phenyltrifluoromethanesulfonate, iodonium bis(4-methylphenyl)hexafluorophosphate (available under the trade name OMNICAT 440 from IGM Resins, Inc. (IGM Resins, Inc., Bartlett, IL, USA)). Resins (Bartlett, IL, USA)), ([4-(octyloxy)phenyl]phenyl iodonium hexafluorophosphate), ([4-(octyloxy)phenyl]phenyl iodonium hexafluoroantimonate), (4-isopropylphenyl)(4-methylphenyl)tetrakis(pentafluorophenyl)borate iodonium (available under the trade name RHODORSIL 2074 from Bluestar Silicones (East Brunswick, NJ, USA)), and 4-(2-hydroxy-1-tetradeepoxy)phenyl]phenyl iodonium hexafluoroantimonate.

[0146] Other suitable photoacid generators are triarylsulfonium salts. Exemplary triarylsulfonium salts include, but are not limited to, triphenylsulfonium hexafluoroantimonate (available from Chitec Technology Corp. (Taipei, Taiwan, China) under the trade name CT-548), diphenyl(4-phenylthio)phenylsulfonium hexafluorophosphate, diphenyl(4-phenylthio)phenylsulfonium hexafluoroantimonate, bis(4-(diphenylsulfonio)phenyl)sulfide bis(hexafluorophosphate), and bis(4-(diphenylsulfonio)phenyl)sulfide hexafluoroantimonate. Blends of triarylsulfonium salts are available from Synasia (Metuchen, NJ, USA) under the trade names SYNAPI-6992 for hexafluorophosphate and SYNA PI-6976 for hexafluoroantimonate. Mixtures of triarylsulfonium salts are commercially available from Aceto Pharma Corporation (Port Washington, NY, USA) under the trade names UVI-6992 and UVI-6976.

[0147] In some embodiments, the anion of the photoacid generator is selected to be the same as the anion of the ionic liquid included in the curable composition. That is, the anion is selected to be SbF6 - PF6 - or a mixture thereof.

[0148] The photoacid generator is typically used in an amount equal to at least 0.5 wt % and up to 5 wt % based on the total weight of the resin component in the curable composition. In some embodiments, the amount is at least 0.5 wt %, at least 0.6 wt %, at least 0.7 wt %, at least 0.8 wt %, at least 1 wt % or at least 2 wt % based on the total weight of the resin component in the curable composition, and up to 5 wt %, up to 3.5 wt %, up to 3 wt %, up to 2.5 wt %, up to 2 wt % or up to 1.5 wt %.

[0149] The curable composition is generally free of both heat activated curing agents and thermal acid generators for epoxy resins. Examples of such heat activated curing agents include, but are not limited to, dicyandiamide (DICY). Examples of thermal acid generators include, but are not limited to, products purchased from King Industries (Norwalk, CT, USA) under the trade names NACURE, TAG, and K-PURE.

[0150] Ionic Liquids

[0151] The curable composition further comprises an ionic liquid. The ionic liquid has a cation containing nitrogen or sulfur and a SbF6 - PF6 - or anions of mixtures thereof. The ionic liquid contains at most one aromatic ring. The ionic liquid has a melting point of less than 100 degrees Celsius. In most embodiments, the melting point is in the range of -45 degrees Celsius to 100 degrees Celsius. The melting point can be determined according to ASTM method E794-06 (reapproved in 2018).

[0152] The ionic liquid is an ammonium salt of formula (VI), a sulfonium salt of formula (VII), an imidazolium salt of formula (VIII), a pyridinium salt of formula (IX), or a pyrrolidinium salt of formula (X).

[0153]

[0154]

[0155] In these formulas, each R 20 , R 21 , R 22 , R 23 and R 24 are independently alkyl, hydroxy-substituted alkyl or a group of formula –(R 30 -O) y -R 31 An ether-containing group, wherein R 30 is an alkylene group, R 31 R is an alkyl group, and y is an integer in the range of 1 to 10. Any of the alkyl and / or alkylene groups may have 1 to 20 carbon atoms, such as at least 1, at least 2, at least 3, or at least 5 and up to 20, up to 18, up to 16, up to 12, up to 10, up to 8, up to 6, up to 4, or up to 3 carbon atoms. Alkylene groups typically have 1 to 3 carbon atoms. In many embodiments, each R 20 , R 21 , R 22 , R 23 and R 24 is an alkyl group, such as a methyl group or an ethyl group.- SbF6 - or PF6 - .

[0156] In some embodiments, the anion (X - ) is selected to be the same as the anion used in the photoacid generator included in the curable composition.

[0157] The amount of the ionic liquid in the curable composition is usually based on the total weight of the curable composition in the range of 0.5 wt % to 20 wt %. The amount can be at least 0.5 wt %, at least 1 wt %, at least 2 wt %, at least 3 wt %, at least 4 wt % or at least 5 wt %, and is at most 20 wt %, at most 18 wt %, at most 15 wt %, at most 12 wt %, at most 10 wt %, at most 8 wt %, at most 6 wt % or at most 5 wt %. For example, the amount can be based on the total weight of the curable composition in the range of 1 wt % to 20 wt %, 1 wt % to 15 wt %, 1 wt % to 10 wt % or 1 wt % to 5 wt %.

[0158] At the end of the useful life of an article containing the cured adhesive, the ionic liquid promotes the debonding of the cured adhesive from the substrate. In particular, the ionic liquid promotes the removal of the cured adhesive from a metal-containing substrate (such as, for example, an electronic component). This allows the metal substrate (e.g., an electronic component) to be reused at the end of the useful life of the article.

[0159] Optional organic solvent

[0160] Although the presence of organic solvents is generally avoided, optional organic solvents may be present in the curable composition. Suitable organic solvents include, but are not limited to, methanol, tetrahydrofuran, ethanol, isopropanol, pentane, hexane, heptane, acetone, methyl ethyl ketone, methyl acetate, ethyl acetate, toluene, xylene, ethylene glycol alkyl ether, propylene glycol carbonate, and mixtures thereof. The organic solvent may be added to dissolve the reactants in the curable composition; may be added to reduce the viscosity of the curable composition, thereby promoting its printing or distribution; or may be a residue from the preparation process of a (meth) acrylate copolymer with a (meth) acryloyl side group. The amount of the organic solvent in the curable composition may be in the range of 0 wt % to 10 wt % based on the gross weight of the curable composition. In some embodiments, the amount is at least 0.5 wt %, at least 1 wt %, at least 2 wt %, at least 3 wt %, at least 4 wt %, and at most 10 wt %, at most 9 wt %, at most 8 wt %, at most 7 wt %, at most 6 wt %, or at most 5 wt %.

[0161] Optional polyol

[0162] The curable composition may optionally include a polyol. The polyol is typically a polymeric material, and is typically a polyether polyol, a polyester polyol, a (meth)acrylic polyol, or a polycaprolactam polyol.

[0163] Polyols can be used as toughening agents and / or can delay the curing reaction of curable compositions. As toughening agents, the presence of polyols can increase the shear strength of the final cured composition. That is, polyols can reduce the crosslinking density and increase the elongation of the cured composition. In addition, some polyols such as polyether polyols tend to increase the "open time" of the curable composition. As used herein, the term "open time" refers to the time after the curable composition has been exposed to ultraviolet and / or visible light radiation, during which the curable composition remains uncured enough to bond to another surface.

[0164] After exposure to UV and / or visible radiation, the open time of the curable composition is desirably at least 2 minutes. In some embodiments, the energy dose is 6 J / cm 2 Up to 9J / cm 2 LED lamps provide UV-A radiation. However, if one or two substrates bonded together are transmissive for the radiation received by the curable composition, the open time is insignificant, because in this case, after the two substrates are attached to each other by the blended filament composition, the acceptance of radiation can be achieved by the transmission substrate. When the two substrates of the assembly are opaque, the blended filament composition is usually subjected to ultraviolet radiation before the second substrate is attached to the blended filament composition. In this case, an open time of at least two minutes can be expected to allow suitable processability in the partially cured composition.

[0165] In many embodiments, polyol is a polyether polyol with at least two or at least 3 hydroxyl groups. Polyether polyol is generally a polyether diol, such as polyoxyalkylene glycol. Some example polyoxyalkylene glycols include but are not limited to polyoxyethylene glycol, polyoxypropylene glycol and polyoxybutylene glycol (which may also be referred to as poly (tetramethylene oxide) glycol or poly (tetrahydrofuran) glycol). Other suitable polyether polyols are polyether triols, such as polyoxyalkylene triols. These triols may be derived from glycerol. Examples include but are not limited to polyoxyethylene triols and polyoxypropylene triols. Polyether polyols may be miscible with other curable components (such as epoxy resin and any optional film-forming resin) or may form a macroscopically stable mixture with them.

[0166] Suitable polytetramethylene oxide glycols include, for example, those commercially available under the trade name POLYMEG from LyondellBasell, Inc. (Jackson, TN, USA), under the trade name TERATHANE from Invista (Newark, DE, USA), and under the trade name POLYTHF from BASF Corp. (Charlotte, NC, USA). Suitable polyoxypropylene polyols include those commercially available under the trade name ARCOL from Bayer Material Science (Los Angeles, CA, USA).

[0167] Other polyether polyols are commercially available from The Dow Chemical Company, Midland, Michigan, USA, under the trade name VORANOL and from Covestro (Leverkusen, Germany) under the trade name DESMOPHEN, such as DESMOPHEN 550U, 1600U, 1900U, and 1950U. Additional polyether polyols are commercially available from The Dow Chemical Company under the trade name CARBOWAX.

[0168] Suitable polyester polyols are commercially available from Covestro of Leverkusen, Germany under the trade name DESMOPHEN, such as DEMMOPHEN 631A, 650A, 651A, 670A, 680, 110 and 1150. Other polyester polyols are available from Evonik of Essen, North Rhine-Westphalia, Germany under the trade name DYNAPOL, which may be linear and saturated, semi-crystalline or amorphous.

[0169] Suitable (meth)acrylate-based polyols are commercially available from Covestro of Leverkusen, Germany under the trade designation DESMOPHEN, such as DESMOPHEN A160SN, A575, and A450BA / A.

[0170] Suitable polycaprolactone polyols are commercially available under the trade designation TONE from The Dow Chemical Company, Midland, Michigan, USA, and under the trade designation CAPA from Ingevity (North Charleston, SC, USA).

[0171] The polyol can be characterized by its hydroxyl number, which refers to the KOH milligrams per gram of hydroxyl-containing material. This can be determined, for example, by adding an excessive amount of acidic substances that react with the polyol, and then by back-titrating the remaining acidic substances with a base to determine the amount of hydroxyl groups per gram of polyol. The amount of hydroxyl groups is recorded as they come from the alkaline substance KOH. The hydroxyl number (mg KOH / gram polyol) is typically at least 10, at least 25, at least 50, at least 75, at least 100, at least 125, at least 150, at least 175, or at least 200, and can be at most 700, at most 650, at most 600, at most 550, at most 500, at most 450, at most 400, at most 350, at most 300, or at most 250.

[0172] In some embodiments, polyol is liquid at room temperature. In other embodiments, polyether polyol is liquid at a temperature higher than 40° C. Polyols that are not liquid at room temperature are generally soluble in other curable components, or if necessary, can be dissolved in an optional organic solvent. The weight average molecular weight can be up to 50,000 daltons, up to 40,000 daltons, up to 20,000 daltons, up to 10,000 daltons or up to 5,000 daltons. For example, the weight average molecular weight is generally at least 100 daltons, at least 500 daltons, at least 750 daltons, at least 1,000 daltons, at least 1,500 daltons or at least 2,000 daltons. In some embodiments, polyether polyol has a weight average molecular weight in the range of 100 daltons to 50,000 daltons.

[0173] In many embodiments, the curable composition contains at least 1% by weight of polyol based on the total weight of the curable components in the curable composition. If there is too little polyol, the curable composition can be cured (polymerized) too fast, and after activating the photoacid generator and positioning the second substrate adjacent to the activated curable composition, there may be insufficient open time. That is, the structural strength of the bonding portion between the first substrate and the second substrate (or the different parts of the first substrate) may be compromised. In addition, if there are not enough polyols, the toughness of the cured composition may be insufficient. The amount of polyol can be in the range of 0% by weight to 30% by weight based on the total weight of the curable components in the curable composition. However, if the amount of polyol is too large, but it may be phase separated, the curable composition may not be semisolid, and the cured composition may have insufficient strength.

[0174] In many embodiments, the amount of the optional polyol is at least 1 wt %, at least 2 wt %, at least 3 wt %, at least 4 wt %, or at least 5 wt %, based on the total weight of the curable components in the curable composition. The amount of the polyether polyol is typically at most 30 wt %, at most 25 wt %, at most 20 wt %, at most 18 wt %, at most 15 wt %, at most 12 wt %, or at most 10 wt %, based on the total weight of the curable components. In some embodiments, the curable composition comprises 0 wt % to 30 wt %, 1 wt % to 30 wt %, 1 wt % to 25 wt %, 1 wt % to 20 wt %, 1 wt % to 15 wt %, 2 wt % to 25 wt %, 2 wt % to 20 wt %, 2 wt % to 15 wt %, 4 wt % to 25 wt %, 4 wt % to 20 wt %, 4 wt % to 15 wt %, 5 wt % to 25 wt %, 5 wt % to 20 wt %, 5 wt % to 15 wt %, 8 wt % to 25 wt %, 8 wt % to 20 wt %, 8 wt % to 15 wt %, 10 wt % to 25 wt %, 10 wt % to 20 wt %, or 10 wt % to 15 wt %.

[0175] Optional silicon dioxide

[0176] Many curable compositions include optional silica particles. Silica is a thixotropic agent and is added to provide shear thinning. When force (shear) is applied, silica has the effect of reducing the viscosity of the curable composition. However, when no force (shear) is applied, the viscosity seems to be higher. That is, the shear viscosity is lower than the static viscosity.

[0177] The silica particles typically have an average longest dimension of less than 500 nanometers, less than 400 nanometers, less than 300 nanometers, less than 200 nanometers, or less than 100 nanometers. The silica particles typically have an average longest dimension of at least 5 nanometers, at least 10 nanometers, at least 20 nanometers, or at least 50 nanometers. In some embodiments, the silica particles are fumed silica. In other embodiments, the silica particles are non-aggregated nanoparticles.

[0178] The amount of optional silica particles is at least 0.5 wt % based on the total weight of the curable composition. The amount of silica can be at least 1 wt %, at least 1.5 wt % or at least 2 wt %, and can be at most 10 wt %, at most 8 wt % or at most 5 wt %. For example, the amount of silica can be in the range of 0.5 wt % to 10 wt %, 1 wt % to 10 wt %, 0.5 wt % to 8 wt %, 1 wt % to 8 wt %, 0.5 wt % to 5 wt %, or 1 wt % to 5 wt %.

[0179] Optional silane

[0180] Various silane compounds may be included in the curable composition. Silanes may be added to promote adhesion to a first substrate and / or a second substrate to which the cured composition is bonded. Silane groups have silyl groups that are particularly effective in increasing adhesion to substrates having hydroxyl groups, such as glass or ceramic surfaces. Silyl groups generally have the formula -Si(R 8 ) x (OR 9 ) 3-x , where each R 8 and each R 9 are independently alkyl. 8 and R 9 The alkyl group of alkylene typically has 1 to 6 carbon atoms, 1 to 4 carbon atoms, or 1 to 3 carbon atoms. The variable x is 0, 1, or 2. The silyl group has at least one alkoxy group that can undergo hydrolysis and react with the siliceous surface.

[0181] Silanes can be hydrophobic or hydrophilic. That is, silanes can have the formula

[0182] R 10 -Si(R 8 ) x (OR 9 ) 3-x , where R 10 Any hydrophobic or hydrophilic group may be used provided that it does not interfere with the cationic polymerization of the epoxy resin. 10 Typically, no nitrogen-containing groups are present. In some embodiments, the silane is a hydrophilic silane and the group R 10 The silane may react with one of the components of the curable composition, such as with a group on a (meth)acrylate copolymer. Such a reaction may result in the silane being covalently attached to the cured composition. For example, some silanes are glycidyl ether silanes, where R 10 Contains a glycidyl group. Examples of such silanes include, but are not limited to, (3-glycidyloxypropyl)trimethoxysilane.

[0183] The amount of optional silane is usually based on the gross weight of curable composition in the range of 0 wt % to 10 wt %. The amount can be at least 0.1 wt %, at least 0.2 wt %, at least 0.3 wt %, at least 0.5 wt % or at least 1 wt %, and at most 10 wt %, at most 8 wt %, at most 6 wt %, at most 5 wt %, at most 4 wt %, at most 3 wt %, or at most 2 wt %. For example, the amount can be in the range of 0.1 wt % to 10 wt %, 0 wt % to 8 wt %, 0.1 wt % to 8 wt %, 0 wt % to 6 wt %, 0.1 wt % to 6 wt %, 0 wt % to 4 wt %, 0.1 wt % to 4 wt %, 0 wt % to 2 wt %, or 0.1 wt % to 2 wt %.

[0184] Other optional components

[0185] Other optional components include, for example, fillers, stabilizers, plasticizers, tackifiers, flow control agents, cure rate retardants, adhesion promoters (e.g., titanates), impact modifiers, expandable microspheres, glass beads or bubbles, thermally conductive particles (e.g., alumina), conductive particles, glass, clay, talc, pigments, colorants, and antioxidants. Optional components can be added, for example, to reduce the weight of a semi-structural or structural adhesive layer, to adjust viscosity, to provide additional reinforcement, to change thermal or conductive properties, to change cure rate, and the like. If any of these optional components are present, they are typically used in an amount that does not interfere with printing or dispensing of the curable composition.

[0186] In many embodiments, the curable composition contains no or substantially no fiber reinforcement. As used herein, "substantially free" means that the curable composition comprises no more than 1 wt%, no more than 0.5 wt%, no more than 0.2 wt%, no more than 0.1 wt%, no more than 0.05 wt%, or no more than 0.01 wt% of fibers.

[0187] Method of forming a curable composition

[0188] Although any suitable method can be used to prepare the curable composition, in many embodiments, a precursor composition is first formed. The precursor composition of the curable composition contains at least a polymerizable composition for forming a statistical (meth) acrylic copolymer. It usually contains a (meth) acrylic triblock copolymer in addition. Forming a precursor composition (which is usually a slurry) can be used to minimize the amount of organic solvent required to form a homogeneous mixture of components included in the curable composition. The slurry contains a polymer material dissolved in a monomer. That is, it contains a solute polymer and a solvent monomer.

[0189] In some first embodiments of forming a syrup for a precursor composition, the solute polymer in the syrup is a (meth)acrylic multi-block copolymer, which is typically a (meth)acrylic tri-block copolymer. In this first embodiment, the solute monomer is a monomer that will be used to form a statistical (meth)acrylic copolymer. More particularly, the solute monomer comprises an alkyl (meth)acrylate and other optional monomers or macromonomers.

[0190] In some second embodiments for forming a slurry for a precursor composition, the solute polymer comprises a partially polymerized reaction product of at least some of the monomers used to form the statistical (meth)acrylic copolymer. In this second embodiment, the solute polymer is typically prepared from alkyl (meth)acrylate monomers and optional monomers. In some examples, any macromonomers included in the statistical (meth)acrylic copolymer are not present when the slurry polymer is prepared, but are added after the slurry polymer is prepared. The (meth)acrylic block copolymer can be present when the slurry is formed, or added after its formation.

[0191] The slurry of the second embodiment can be formed using a free radical initiator, which can be a thermal initiator or a photoinitiator. Any thermal initiator and photoinitiator described above for preparing statistical (meth) acrylic copolymers can be used. The extent of the reaction can be controlled by monitoring the viscosity of the slurry. For example, the reaction can be terminated when the viscosity reaches about 1000 centipoise. The reaction is stopped by lowering the temperature or removing the light source used to activate the initiator.

[0192] In some embodiments, the slurry of the second embodiment is formed using a photoinitiator that can be activated by exposure to ultraviolet radiation having a wavelength of less than 380 nanometers (nm), such as in the range of 300 nm to less than 380 nm. For example, the free radical initiator can be activated at a wavelength between 300 nm and 370 nm, between 330 nm and 370 nm, between 350 nm and 370 nm, or close to 365 nm. One such photoinitiator is 2,2-dimethoxy-2-phenylacetophenone, which is available from BASF Corporation of Florham Park, New Jersey, USA under the trade name "IRGACURE 651".

[0193] The slurry from the first embodiment or the second embodiment is combined with other components of the curable composition (e.g., epoxy resin, photoacid generator, ionic liquid and (meth) acrylic multi-block copolymer (if it is not present in the slurry), and additional monomers for forming statistical (meth) acrylic block copolymers (which are not present in the slurry)). In addition, a free radical initiator, such as those mentioned above for forming (meth) acrylic copolymers, can be added. The added free radical initiator is typically a phosphine oxide, such as phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide (commercially available from BASF under the trade name "IRGACURE 819"). These free radical photoinitiators can be activated by exposure to a first actinic light source. This activation causes the solute monomers in the slurry to polymerize (e.g., any ethylenically unsaturated monomers and / or macromonomers in the precursor composition to polymerize). The reaction product is a curable composition. To avoid inadvertently triggering both the free radical photoinitiator for forming the statistical (meth)acrylic copolymer and the photoacid generator for polymerizing the epoxy resin, the first actinic light source is selected such that it emits at a wavelength that is not significantly absorbed by the photoacid generator.

[0194] The first actinic light source is selected to produce a spectral output having a peak intensity at a first wavelength of at least 380 nanometers (nm), at least 383 nm, at least 386 nm, at least 390 nm, or at least 393 nm. The peak intensity of the first actinic light source may be at a wavelength of at most 420 nm, at most 419 nm, at most 418 nm, at most 417 nm, or at most 416 nm. The excitation dose for activating the photoinitiator may be at least 200 mJ / cm 2 , at least 400mJ / cm 2 , at least 600mJ / cm 2 , at least 800mJ / cm 2 , at least 1000mJ / cm 2 , at least 1500mJ / cm 2 , or at least 2000mJ / cm 2 The excitation dose can be up to 6400mJ / cm 2 , up to 6000mJ / cm 2 , up to 5000mJ / cm 2 , up to 4000mJ / cm 2 , up to 3000mJ / cm 2 , up to 2500mJ / cm 2 , or up to 2000mJ / cm 2 .

[0195] One class of first actinic light sources that can be used is light emitting diodes ("LEDs"). LED-based ultraviolet (UV) sources are advantageous because they provide UV light in a narrower wavelength range than other UV light sources, such as black lights and mercury lamps. LED sources are commercially available that emit radiation at, for example, 395 nm or 405 nm.

[0196] The precursor composition can be applied to a first substrate (or, alternatively, a first release liner) prior to exposure to a first wavelength of actinic radiation. In many embodiments, the precursor composition is coated onto a release liner prior to exposure to ultraviolet radiation of the first wavelength. The precursor composition undergoes a free radical polymerization reaction upon exposure to the first wavelength of actinic radiation, thereby resulting in the formation of a statistical (meth)acrylic copolymer. The reaction product is a curable composition disposed on a release liner. The curable composition comprises (1) a (meth)acrylic multi-block copolymer, (2) a statistical (meth)acrylic copolymer, (3) an epoxy resin, (4) a photoacid generator, and (5) an ionic liquid.

[0197] In some cases, the curable composition can be subjected to a sustained stress level that may cause creep and / or oozing out under environmental conditions. The source of such stress may include, for example, winding tension or stacking weight. The curable composition can be stored for an extended time with a minimum amount of creep and / or oozing out after being exposed to the first actinic light source. The curable composition is given dimensional stability by the presence of a combination of a (meth) acrylic multi-block copolymer that can form physical crosslinking and a statistical (meth) acrylic copolymer that can be chemically crosslinked.

[0198] Since curable compositions have a shelf life, manufacturers can prepare articles containing curable compositions attached to a first substrate or a release liner. Subsequently, the consumer can irradiate the curable composition with light of a second wavelength and then position the irradiated composition adjacent to the second substrate. That is, the final curing step is completed by the consumer. If part of the curable composition is located on a release liner, the curable composition can be attached to the first substrate after the release liner is removed and then exposed to actinic radiation of the second wavelength.

[0199] The curable composition is generally used as a pressure-sensitive adhesive. In some embodiments, the curable composition is positioned between a first release liner and a second release liner. The first release liner can be removed to place the curable composition adjacent to the first substrate, while the second substrate can be removed to place the curable composition adjacent to the second substrate.

[0200] Cured compositions and methods of forming cured compositions

[0201] The cured composition is the polymerization reaction product of the curable composition.The cured composition comprises a (meth)acrylic multi-block copolymer, a statistical (meth)acrylic copolymer, and a polymerized (cured) epoxy resin.

[0202] Since the curable composition is usually a pressure-sensitive adhesive, it can be attached to various substrates. In many embodiments, the curable composition is positioned adjacent to the first substrate. The curable composition can then be exposed to the actinic radiation of the second wavelength to start the curing of the epoxy resin. After being exposed to the actinic radiation of the second wavelength, the curable composition is positioned adjacent to the second substrate. In other words, the curable composition is positioned between the first substrate and the second substrate. The curable composition can attach two substrates together by acting as a pressure-sensitive adhesive until the curing is completed. When curing, the first substrate can be bonded to the second substrate by the cured composition. The curing composition is generally a semi-structural or structural adhesive. If necessary, the curable composition can be easily positioned adjacent to the second substrate so that the second substrate is attached to the first substrate by the curable composition. In other words, the curable composition as a pressure-sensitive adhesive can be positioned between the first substrate and the second substrate and attached to two substrates.

[0203] Typically, the curable composition is exposed to light of a second wavelength prior to being positioned adjacent to the second substrate to activate the photoacid generator. The term "actinic radiation of a second wavelength" or similar terms may refer to a single wavelength or a distribution of wavelengths that activate the photoacid generator. The second wavelength is from a second light source that produces a spectral output having a peak intensity at a second wavelength different from the first wavelength. The photoacid generator preferentially absorbs radiation emitted by the second actinic light source relative to radiation emitted by the first actinic light source. That is, the photoacid generator preferentially absorbs little or no radiation emitted by the first actinic light source.

[0204] In many embodiments, the second wavelength is shorter than the first wavelength. Similar to the first light source, the second light source typically has a controlled spectral output, wherein the distribution of wavelengths is relatively narrow (or "substantially monochromatic") and centered at a characteristic second wavelength, such as a wavelength corresponding to peak intensity. However, this is not critical, and other wavelength distributions, including multi-modal distributions, are also feasible.

[0205] The second wavelength is selected to activate the photoacid generator in the second curable composition. These compounds generate acid when activated. In many embodiments, the second wavelength is at least 200nm, at least 250nm, at least 300nm, at least 330nm, or at least 356nm. The second wavelength can be less than 380nm, at most 377nm or at most 374nm.

[0206] Since the reaction of the curable composition occurs after the statistical (meth) acrylic copolymer is formed from the precursor composition, the properties of the second actinic light source need not be as limited as the properties of the first actinic light source. The second actinic light source may be based on an LED source, as previously described. Alternatively, the second actinic light source may be an ultraviolet black light, a mercury lamp, or another broad spectrum light source.

[0207] UV blacklight is a relatively low light intensity source that typically provides 10 mW / cm2 in the wavelength range of 280 nm to 400 nm. 2 or less (as measured according to procedures approved by the National Institute of Standards and Technology, as measured, for example, with a UVIMAP UM 365L-S radiometer manufactured by Electronic Instrumentation & Technology, Inc., Sterling, VA).

[0208] Mercury lamps are a more intense broadband UV source, providing typically greater than 10 mW / cm 2 , preferably between 15mW / cm 2 With 6000mW / cm 2 For example, 600 mW / cm 2 The intensity can be 0.1mW / cm 2 Up to 6000mW / cm 2 , and preferably at 0.5 mW / cm 2 Up to 3000mW / cm 2 within the range.

[0209] Where monochromatic light sources are typically used, the first and second actinic light sources may be selected to operate at different wavelengths; for example, they may have respective peak intensities at wavelengths separated by at least 10 nanometers, at least 15 nanometers, at least 20 nanometers, at least 25 nanometers, or at least 35 nanometers. The first and second actinic light sources may have respective peak intensities at wavelengths separated by at most 100 nanometers, at most 80 nanometers, at most 60 nanometers, at most 50 nanometers, or at most 45 nanometers.

[0210] When the curable composition is exposed to actinic radiation of the second wavelength, the epoxy resin polymerizes. The cured composition comprises the reaction product of the curable composition. In addition, exposure to light of the second wavelength can induce covalent bonding between the functional groups (e.g., hydroxyl groups) of the statistical (meth) acrylic copolymer and the epoxy resin. Thus, the cured composition can be covalently bonded to various polymers in the curable composition.

[0211] The amount of time required to form a functional semi-structural bond or structural bond after irradiation with a second actinic light source can be at least 1 minute, at least 2 minutes, at least 5 minutes, at least 10 minutes, at least 20 minutes, at least 30 minutes, at least 1 hour, at least 2 hours, at least 4 hours, at least 8 hours, at least 12 hours, at least 18 hours, or at least 24 hours. In some cases, the time periods specified above can be achieved by heating the adhesive composition.

[0212] The curable composition, before being fully cured, usually and preferably has the characteristics of a pressure-sensitive adhesive. Preferably, the pressure-sensitive adhesive has sufficient viscosity and dimensional stability to avoid the use of a fixture or other mechanism to fix the first substrate to the second substrate for the entire second curing reaction. Typically, a fixture or other mechanism is used in the early stages of curing the second curable composition to ensure that it fully wets the surface to which it is attached.

[0213] Products

[0214] The present invention provides various articles. A first article includes a curable composition and at least one substrate or release liner. A second article includes a cured composition positioned between two substrates such that the first substrate is bonded to the second substrate.

[0215] The first article comprises a curable composition and a first substrate, or a first release liner positioned adjacent to the first substrate or the first release liner. The curable composition is the same as described above. Some first articles comprise a curable composition, and a first substrate positioned adjacent to the curable composition. Optionally, a release liner can be positioned on a surface of the curable composition opposite to the first substrate. Other first articles comprise a curable composition and a first release liner positioned adjacent to the curable composition. Optionally, a second release liner can be positioned on a surface of the curable composition opposite to the first release liner.

[0216] In the case where the first substrate is a flexible substrate, or in the case where there is no first substrate (e.g., in the case where the article includes a first release liner and an optional second release liner), the first article can be in the form of a roll. In some rolls, there are two release liners on the opposite surfaces of the curable composition. In other rolls, there is a single release liner. The article with one or two release liners can be a transfer adhesive tape. The article is typically a die cut piece of a shape and size consistent with the intended use of the curable composition.

[0217] In some embodiments, the article comprising the curable composition can be stored adjacent to at least one release liner for any desired amount of time, such as up to 1 week, up to 2 weeks, up to 1 month, up to 2 months, up to 4 months, up to 6 months, up to 8 months, up to 10 months, or up to 1 year.

[0218] The curable composition in the first product is a pressure sensitive adhesive. In some embodiments, the first product is a transfer adhesive tape. In many embodiments, the first product does not need to be reinforced with fibers, such as described in U.S. Patent Application Publication No. 2002 / 0182955 (Weglewski et al.).

[0219] The second product includes a first substrate, a second substrate, and a cured composition positioned between the first substrate and the second substrate. The same cured composition as above bonds the first substrate to the second substrate. The curable composition of the first product can have excellent anti-exudation properties, and can be used to form a second product containing a cured composition that can be used as a semi-structural adhesive with good impact resistance. If necessary, the cured composition in the second product can be debonded, and the cured composition can be removed (e.g., debonded) from various surfaces of the second product after the service life of the product to correct the misalignment of parts during manufacturing, or repair products (such as electronic devices).

[0220] Any suitable first substrate and second substrate can be used. Usually, at least one of the first substrate and the second substrate contains metal and / or is conductive. The substrate can be flexible or non-flexible. The substrate can be formed by polymer material, glass, ceramic material, metal (including various alloys) or a combination thereof. In many embodiments, the first substrate and / or the second substrate are glass, ceramic material or metal. Suitable polymer material can be selected from polymer film or plastic composite (for example, glass or fiber-filled plastic). The polymer material can be prepared, for example, by polyolefin (for example, polyethylene, polypropylene or their copolymer), polyurethane, polyvinyl acetate, polyvinyl chloride, polyester (polyethylene terephthalate or polyethylene naphthalate), polycarbonate, poly (methyl) acrylate (PMMA), ethylene-vinyl acetate copolymer and cellulose material (for example, cellulose acetate, cellulose triacetate and ethyl cellulose). If desired, the non-conductive substrate can be coated with a conductive layer.

[0221] Release liners can be used to make articles and serve as temporary substrates. That is, release liners are substituted with permanent substrates. Suitable release liners generally have low affinity for curable compositions. Exemplary release liners can be prepared from paper (e.g., kraft paper) or other types of polymeric materials. Some release liners are coated with an outer layer of a release agent, such as a material containing silicone or a material containing a fluorocarbon (e.g., polyfluoropolyether or polyvinyl fluoride).

[0222] In some embodiments, the first substrate and the second substrate can be different parts of an electronic device, a motor vehicle, or a household appliance. For example, one of these substrates can be a polymer display frame, and the second substrate can be a polymer or metal housing in a phone, a tablet computer, or other electronic device. Alternatively, the two substrates can be different parts of a motor vehicle (such as a car, a truck, an airplane, etc.), or different parts of a household appliance (such as a refrigerator, a dishwasher, an oven, a washing machine, or a dryer). For example, one of the substrates can be glass (such as in a windshield or an electronic display or a shelf), and the second substrate can be a polymer or metal frame or bracket.

[0223] If at least one substrate is electrically conductive, the second article can be separated into its component parts by applying a DC potential. For example, after the useful life of the second article or when the second article needs to be repaired, the first substrate and the second substrate can be separated from each other. In many embodiments, the cured composition can be cleanly removed from the substrate. This removal allows the substrate to be reused. This is particularly advantageous when the curable composition is attached to the first or second substrate, which is or contains electronic components that can be reused or recycled.

[0224] The shape and form of the article are not particularly limited. The article can be a finished product or a part for being incorporated into or attached to another object. The article is usually composed of at least two parts that can be bonded together in an adhesive manner, and the article can be a two-dimensional or three-dimensional shape. Similarly, the shape and form of the parts constituting the article are not particularly limited. The parts can be a single element or a combination of elements, and the parts can be two-dimensional or three-dimensional. In some embodiments, two or more parts are interconnected, or even two different parts of the same material are interconnected (for example, one end of a composite tape can be folded to be bonded to the opposite end of the tape).

[0225] Debonding

[0226] For the convenience of separating the parts (for example, substrate) joined together by the composition (that is, adhesive composition) of solidification, before separating the parts, direct current (DC) potential is applied across the adhesive composition.For example, potential can be applied across two conductive components on the opposite side of the adhesive composition, so that the surface of a component is used as a negative electrode (or negative adhesive interface) and the surface of another component is used as a positive electrode (or positive adhesive interface).Or, potential can be applied across a conductive component and a conductive adhesive carrier of a double-sided tape, wherein the surface of the conductive component or the conductive adhesive carrier is used as a negative adhesive interface, and another surface of the conductive component or the conductive adhesive carrier is used as a positive adhesive interface.Applying DC current usually weakens the adhesive bonding at the negative electrode-adhesive interface, thereby reducing the amount of force required for the parts in the separated product.The position of debonding can be reversed by simply changing the polarity of the potential.

[0227] FIG. 1 shows one embodiment of an article of the present disclosure comprising two conductive components joined together by an adhesive composition. Figure 1A , the article 10 includes a first component 12 having a first conductive surface 14 and a second component 22 having a second conductive surface 24. The first component and the second component 12, 22 are each made of a conductive material. The nature of the conductive material is not particularly limited. In some embodiments, the first conductive surface 14 and the second conductive surface 24 are each selected from: metals, mixed metals, alloys, metal oxides, composite metals, conductive plastics, conductive polymers, or combinations thereof. In some embodiments, the composition of the first conductive surface 14 is different from the composition of the second conductive surface 24. In other embodiments, the composition of the first conductive surface 14 and the second conductive surface 24 is the same.

[0228] The adhesive composition 30 joins the first component 12 and the second component 22 together at the first conductive surface 14 and the second conductive surface 24. By applying a DC potential across the adhesive composition 30, the adhesive composition exhibits on-demand debonding behavior. In this embodiment, the first conductive surface 14 serves as a positive adhesive interface and the second conductive surface 24 serves as a negative adhesive interface. Applying a DC potential 40 across the adhesive composition 30 results in a weakening of the adhesive bond at the negative adhesive interface (i.e., the second conductive surface 24), as measured, for example, according to the work of adhesion per unit surface area, thereby making it easier to separate the second component 22 from the first component 12. Preferably, almost no adhesive residue remains on the second conductive surface 24 after separation. In some embodiments, less than 10%, less than 5%, or less than 1% of the adhesive composition (by weight) remains on the second component 22 after separation. In some preferred embodiments, no adhesive composition remains on the second component 22 after separation. In some embodiments, the adhesive composition can be reused, allowing the first component 12 to be rejoined to the second component 22 or attached to a completely different component or article. If it is desired that adhesive remain on the second component 22 after separation, the polarity of the DC potential can be reversed so that the first conductive surface 14 serves as a negative adhesive interface.

[0229] Conductive components include those components made entirely of conductive materials, such as Figure 1A As shown, and those parts made of non-conductive materials coated with conductive materials, such as Figure 1B Reference Figure 1B , the first component 12 includes a first non-conductive material 16 and a first conductive coating 18 to provide the first conductive surface 14. Similarly, the second component 22 includes a second non-conductive material 26 and a second conductive coating 28 to provide the second conductive surface 24. Alternatively (not shown), one of the components may be made entirely of a conductive material and the other component may be made of a non-conductive material coated with a conductive material. The conductive coating may only partially coat the components, such as Figure 1B As shown, or completely coat the outer surface of the component. For the purpose of the present disclosure, only the surface of the component in direct contact with the adhesive composition needs to be fully coated to weaken the adhesive bonding at the negative adhesive interface when a DC potential is applied across the adhesive composition. In some embodiments, the coating is a solid layer. In other embodiments, the coating is pattern-coated on the surface of the component. As mentioned above, the conductive material is not particularly limited and can include a material selected from the following: metal, mixed metal, alloy, metal oxide, composite metal, conductive plastic, conductive polymer or a combination thereof.

[0230] Figure 1BThe adhesive composition 30 in the adhesive composition 30 bonds the first component 12 and the second component 22 together. The first conductive surface 14 serves as a positive adhesive interface, and the second conductive surface 24 serves as a negative adhesive interface. Applying a DC potential 40 across the adhesive composition 30 results in a weakening of the adhesive bond at the negative adhesive interface (i.e., the second conductive surface 24), as measured, for example, in terms of work of adhesion per unit surface area, thereby making it easier to separate the second component 22 from the first component 12. If it is desired that the adhesive composition remain primarily on the second component, the polarity of the DC potential can be reversed so that the first conductive surface serves as a negative adhesive interface.

[0231] Figure 1A to Figure 1B The article in the invention may further be suitable for bonding non-conductive objects or components using the adhesive composition and subsequently debonding (i.e., separating) them, such as Figure 1C shown. Figure 1C The article in the embodiment includes a conductive first component 12 having a first conductive surface 14 and a conductive second component 22 having a second conductive surface 24. The first component 12 and the second component 22 are bonded together by an adhesive composition 30. Although the first component and the second component can be made of conductive materials, it should also be understood that the first component and / or the second component can be made of a non-conductive material and coated with a conductive material, such as Figure 1B shown. Figure 1C and Figure 1A and Figure 1BThe difference is that the first external adhesive 50 is added to the second side 19 of the first part 12 opposite to the adhesive composition 30, and the second external adhesive 60 is added to the first side 29 of the second part 22 opposite to the adhesive composition 30. External adhesives 50 and 60 can be the same or different, and there is no particular limitation, as long as the external adhesives 50 and 60 are bonded to non-conductive objects or elements and used for intended applications. In some embodiments, the external adhesive is a pressure-sensitive adhesive. In some other embodiments, the external adhesive is a curable composition as described herein. An optional release liner (not shown) can be applied to the first external adhesive 50, the second external adhesive 60 or both, to protect the external adhesive during transportation and storage of the article. In some embodiments, a release liner is applied to each external adhesive in the first external adhesive and the second external adhesive. In other embodiments, a release liner is applied to one of the external adhesives, and the article itself is rolled up so that another external adhesive is in direct contact with the release agent of the release liner for the purpose of storage and transportation. The adhesive composition can then be unfolded when ready to use. The release liner can be made of, for example, a composite of kraft paper, polyethylene, polypropylene, polyester, or any of these materials. The liner is preferably coated with a release agent such as a fluorochemical or siloxane. In some preferred embodiments, the liner is a paper, polyolefin film, or polyester film coated with a silicone release material. Examples of commercially available release liners include POLYSLIK silicone release paper from Loparex (Cary, NC) in Cary, North Carolina, silicone 1750 coating film from Infiana (Forchheim, Germany) in Forchheim, Germany, silicone terephthalate film from HP Smith Co. (Stoneham, MA) in Stoneham, Massachusetts, and 3M SCOTCHPAK 9741 release liner from 3M Company (St.Paul, MN) in St. Paul, Minnesota.

[0232] exist Figure 1C In the illustrated embodiment, the first component and the second component are two-dimensional (e.g., sheets or multilayer films). However, this is not required, and applications where one or both components are three-dimensional are envisioned (e.g., special mounting features, such as formed grooves in which non-conductive objects are seated). In practice, one of the optional release liners is removed from the first external adhesive 50 and the first external adhesive is attached to the non-conductive object. Then, the second optional release liner is removed from the second external adhesive 60, and the second external adhesive 60 is attached to a different non-conductive object, so that the non-conductive objects are joined in an adhesive manner. As shown in FIG. Figure 1A to Figure 1B As shown, non-conductive objects can be separated on demand by applying an electric potential across the adhesive composition. In this case, the separation will result in one non-conductive object having a first component adhesively bonded thereto and the other non-conductive object having a second component adhesively bonded thereto.

[0233] FIG. 2 illustrates another embodiment of an article 110 of the present application, wherein the adhesive composition is a double-sided tape that joins a first component and a second component together.

[0234] refer to Figure 2A , the article 110 includes a first component 112 having a first conductive surface 114 and a second component 122 having a second conductive surface 124. The first component and the second component can be made of conductive materials, such as Figure 2A As shown, one or both of the first and second components may be made of a non-conductive material and at least partially coated with a conductive material, as described above with respect to FIG. Adhesive composition 130 is disposed between first and second conductive surfaces 114, 124 and bonds first component 112 to second component 122.

[0235] Adhesive composition 130 is a double-sided adhesive, which also includes a carrier 170 having a first major surface 172 and a second major surface 174 opposite to the first major surface. The first adhesive composition 132 is located on the first major surface 172 of the carrier 170. Similarly, the second adhesive composition 134 is located on the second major surface 174 of the carrier 170. In some embodiments, the composition of the first adhesive composition is the same as the composition of the second adhesive composition. In other embodiments, the composition of the first adhesive composition is different from the composition of the second adhesive composition. The surface 136 of the first adhesive composition 132 opposite to the carrier 170 contacts the first conductive surface 114 of the first component 112. The surface 138 of the second adhesive composition 134 opposite to the carrier 170 contacts the second conductive surface 124 of the second component 122.

[0236] In some embodiments, carrier is a porous material that allows physical contact between the first adhesive composition and the second adhesive composition. Exemplary carriers include paper, woven or nonwoven fabrics, porous membranes, metal mesh, metal grids, or a combination thereof. In some embodiments, carrier is conductive. Such conductive carriers can be porous or nonporous, and include metal mesh, metal grids, metal foils, metal plates, conductive polymers, conductive foams, conductive tissues, or a combination thereof.

[0237] exist Figure 2AIn the illustrated embodiment, the first conductive surface 114 serves as a positive adhesive interface and the second conductive surface 124 serves as a negative adhesive interface. When the carrier is made of a porous material, applying a DC potential 140 across the adhesive composition 130 results in a weakening of the adhesive bond at the negative adhesive interface (i.e., the second conductive surface 124), as measured, for example, in terms of work of adhesion per unit surface area, thus making it easier to separate the second component 122 from the first component 112. If it is desired to separate the adhesive composition from the first component, the polarity of the DC potential can be reversed so that the first conductive surface serves as a negative adhesive interface.

[0238] when Figure 2A When the carrier in is a non-porous conductive material, applying a DC potential 140 across the adhesive composition 130 may result in weakening of the adhesive bond at the negative adhesive interface (ie, the second conductive surface 124 ) and the first major surface 172 of the carrier 170 .

[0239] In another embodiment, carrier 170 is a conductive material that acts as a positive or negative adhesive interface during the debonding process. Figure 2B , the first conductive surface 114 of the first component 112 is a positive adhesive interface, and the first major surface 172 of the carrier 170 is a negative adhesive interface. Applying a DC potential 140 across the first adhesive composition 132 will cause the first and second components 112, 122 to separate at the first major surface 172 of the carrier 170. Alternatively, the first component 112 can be removed from the first adhesive composition 132 by reversing the polarity of the DC potential.

[0240] In additional embodiments, the conductive surface 124 of the second component 122 or the second major surface 174 of the carrier 170 can be a negative adhesive interface and the other of the conductive surface 124 of the second component 122 or the second major surface 174 of the carrier 170 can be a positive adhesive interface.

[0241] It should be understood that reference Figure 2B, when the carrier 170 is used as a negative or positive adhesive interface and the first conductive surface 114 of the first component 112 is used as the other of the negative or positive adhesive interfaces, only the first adhesive composition 132 across which a DC potential is applied needs to include a cured composition comprising an ionic liquid. The second adhesive composition 134 can be virtually any type of adhesive. Similarly, when the carrier 170 is used as a negative or positive adhesive interface and the second conductive surface 124 of the second component 122 is used as the other of the negative or positive adhesive interfaces, only the second adhesive composition 134 across which a DC potential is applied needs to include a cured composition comprising an ionic liquid. The first adhesive composition 132 can be any type of adhesive. Therefore, in such embodiments, a double-sided tape can be used to prepare an article comprising a carrier having adhesives on both sides, wherein only one of the adhesives comprises a cured composition comprising an ionic liquid. This construction would be similar to Figure 1C The configuration shown in , in which the second component 22 is a carrier.

[0242] As shown above, double-sided tapes with a conductive carrier allow the user to strategically customize the location of debonding within an article. This can be particularly advantageous when it is necessary to remove adhesive from a part before recycling and / or leave adhesive on the part for repositioning or bonding to the same or different article.

[0243] Furthermore, by using a double-sided tape with a conductive carrier, at least one of the components does not need to be conductive to separate the first component from the second component. The carrier can be used as one of the electrodes, thereby increasing the types of materials that can be included in the article (i.e., bonding two conductive components or bonding a conductive component to a non-conductive component).

[0244] Example

[0245] Unless otherwise indicated or readily apparent from the context, all parts, percentages, ratios, etc. in the examples and the remainder of the specification are by weight.

[0246] Table 1. Materials used in the examples

[0247]

[0248]

[0249] Test Method

[0250] Dynamic shear strength

[0251] For dynamic shear testing, a modified version of "ASTM D1002 - Apparent Shear Strength of Metal Specimens Bonded to Single Lap Joints" was used. The curable adhesive samples were tested between the ends of two overlapping 304 stainless steel substrates (25.4 mm wide x 101.6 mm long x 1.6 mm thick), where the overlapping adhesive bonding area was 25.4 mm x 25.4 mm. To prepare the bonding test specimens, 25.4 mm x 25.4 mm square specimens of the curable adhesive were cut, which contained a layer of adhesive composition between two release liners (RF02N and RF12N). The easy release liner (RF02N) was removed and the curable adhesive was laminated to the end of the first substrate at room temperature. The tight liner (RF12N) was removed from the curable adhesive bonded to the first stainless steel substrate. The curable adhesive was exposed to 4J UV-LED radiation at 365 nm, and the end of the second stainless steel substrate was immediately applied to the adhesive area, ensuring an overlap area of ​​25.4 mm x 25.4 mm. The total UV energy was determined using a POWERPUCKII radiometer (available from EIT Incorporated, Sterling, Virginia, USA). The bonded laminate (cured adhesive between two stainless steel substrates) was then compressed for 30 seconds at room temperature with a 4 kg weight applied to the 25.4 mm x 25.4 mm adhesive bond area. The bonded test specimens were then compressed together over the bonded portion with an adhesive clamp (large, Staples, Framingham, Massachusetts) for 300 seconds and then placed in an oven at 65°C with the clamp removed for 30 minutes. The bonded test specimens were then placed at 23°C and 50% relative humidity (RH) for 2 days before testing. Adhesive joints were tested by clamping the opposite ends of two stainless steel substrates in an MTS CRITERION (Model C43, MTS, Eden Prairie, Minnesota, USA), and the test was conducted at a displacement rate (vertical crosshead speed) of 10 mm / min. The maximum peak in stress of the stress-strain curve was used to determine the peak stress (in MPa) of the cured adhesive sample of Table 3.

[0252] Tensile extrusion strength

[0253] The stretch extrusion device is shown in Figure 3. A square stainless steel (SS) specimen 230 (40 mm × 40 mm × 3 mm) containing a circular hole (24 mm in diameter) in the center and a circular stainless steel disc 210 (diameter = 33 mm, 3 mm thick) were attached together using a circular die-cut curable adhesive 220 (outer diameter = 31 mm, inner diameter = 26 mm, 200 μm thick). Initially, the die-cut curable adhesive was positioned between two release liners (RF02N and RF12N). The die-cut easy-release liner (RF02N) was removed and the die-cut was attached symmetrically around the center hole of the SS specimen. The tight liner (RF12N) was then removed and the curable adhesive was exposed to 4J UV-LED radiation at 365 nm for curing. The total UV energy was determined using a POWERPUCK II radiometer (purchased from EIT Co., Ltd., Sterling, Virginia, USA). The SS disc was then centered above the cured adhesive die-cut and attached to the exposed adhesive surface by hand pressure. The assembly was then compressed with a 4 kg weight for 30 seconds at 23° C. The bond test specimens were then compressed together at the bonded portion using adhesive clamps (large, Staples, Framingham, MA) for 300 seconds and then placed in an oven at 65° C. for 30 minutes with the clamps removed. The bond test specimens were then placed at 23° C. and 50% relative humidity (RH) for 2 days before testing.

[0254] For electrically induced debonding, a BK Precision 1685B power supply (Yorba Linda, California, USA) was connected to the sample block and the disk via positive and negative electrodes. A voltage of 50 V (DC potential) was applied between the sample and the disk for 180 seconds or 300 seconds. After this time, the sample was immediately disconnected from the power supply electrodes and loaded onto an MTS CRITERION (Model C43, MTS, Eden Prairie, Minnesota, USA). Figure 3 The disc was extruded from the specimen at a rate of 10 mm / min in the direction indicated. The peak stress required to remove the disc from the specimen was recorded in MPa and the percentage reduction compared to the extrusion strength without applied voltage was recorded and is shown in Table 3. Samples without applied voltage were also tested in this manner and the peak stresses of these measurements are also reported in Table 3.

[0255] Molecular weight determined by size exclusion chromatography (SEC)

[0256] The samples submitted were analyzed according to polystyrene molecular weight standards by conventional SEC. Solvent and eluent consisted of tetrahydrofuran (OMNISOLV grade, stabilized with 250ppm of butylated hydroxytoluene, from EMD Millipore (Burlington, Massachusetts, USA)). SEC equipment is composed of 1100 systems (including quaternary pumps, autosamplers, column chambers, differential refractive index detectors) from Agilent Technologies (Santa Clara, CA, USA) in Santa Clara, California, USA, which use the above-mentioned eluents to operate at a flow rate of 1.0mL / min. The stationary phase is composed of PLgel MIXED-C+D columns (5 micron particle sizes, 7.5mm internal diameter, each 30cm long) from Agilent Technologies. The column chamber and differential refractive index detector are set to 40°C. Samples are prepared separately, and the injection preparations are prepared in duplicate. It is assumed that the polymer content in the sample is about 5% by weight. A solution with a concentration of about 60 mg / mL (or about 3 mg / mL after adjusting for polymer content) was prepared in a glass scintillation vial using the above solvent. A 1 mL aliquot was filtered through a 0.45 mm PTFE syringe filter into an automatic sampling bottle. The vial was compressed with an aluminum cap and placed in the autosampler of the SEC system for analysis. The injection volume was set to 50 μL. The molecular weight standard was EasiCal polystyrene from Agilent Technologies. The peak molecular weight values ​​of the polystyrene molecular weight standards used in the calibration were in the range of 2,403,000 g / mol to 580 g / mol. The molecular weight calibration curve was 3rd order, y=-0.003115x^3+0.1288x^2-2.178x+17.98. The software used for data collection was OpenLAB CDS, ChemStation Edition for LC&MS Systems from Agilent Technologies. The software used for data analysis was Agilent GPC / SEC software (version A.02.01) from Agilent Technologies.

[0257] Glass transition temperature determined by dynamic mechanical analysis

[0258] Rheological tests were performed using a TA Instruments discovery hybrid rheometer III (DHR-3) (New Castle, DE, USA) with 8-mm diameter parallel plates. The sample was mounted between parallel plates (completely filling the plate) and heated from room temperature to 40°C. The sample was then subjected to a cooling temperature ramp from 40°C to -50°C at a rate of 3°C / min. The temperature was then set to 20°C, and the sample was then subjected to a heating temperature ramp from 20°C to 140°C at a rate of 3°C / min. In these two temperature ramp steps, the viscoelastic data of the sample was collected by applying an oscillating rotational shear deformation with a frequency of 1Hz, and the strain amplitude value was in a linear viscoelastic state (usually 1% to 5% or less). According to the rheological curves of G' and G' (y axis-1) relative temperature (°C) (x axis) and tan (δ) (y axis-2), the glass transition temperature (at 1Hz) was determined as the peak of the tan (δ) curve. The peak (ie, highest value) in tan(δ) is selected from the y-axis -2, and the corresponding temperature on the x-axis is selected as the glass transition temperature. Tan(δ) is an abbreviation for the tangent of the phase angle between stress and strain oscillation waves in a shear rheology oscillation diagram.

[0259] Sample preparation

[0260] Examples and Comparative Examples

[0261] Syrups SRP-1 and SRP-2 were prepared using LA2330 / monomer mixtures, wherein SRP-1 contained LA2330 in nBuA monomer (40 wt% by mass) and SRP-2 contained LA2330 in 2-MBA monomer (30 wt% by mass). SRP-1 and SRP-2 were prepared by dissolving LA2330 polymer at the specified solids wt% in the corresponding monomers at room temperature without further processing.

[0262] The transfer tape samples were prepared by mixing the additive raw materials (RM) and syrup at the appropriate parts per hundred resin (phr) loadings listed in Table 2A and Table 3 (raw materials are described in Table 1), whereby 100 phr of syrup was used in Table 2A. The monomer-polymer / epoxy resin / initiator / crosslinker syrup mixture was then coated between two release liners (RF12N and RF02N, available from SKC Haas, Seoul, Korea, 2 mil) at an adhesive thickness of 8 mils (200 μm) and exposed to 405 nm UV-LED lamp at 2.8 J / cm 2 The acrylic RM of the tape was cured with a total dose of , which was measured using a POWER PUCK II radiometer (available from EIT Inc., Sterling, VA, USA) equipped with a high power sensing probe.

[0263] These curable compositions are described in both Table 2A and Table 2B. Table 2B gives the weight percentages based on the total weight of the resin composition in the curable composition.

[0264] Table 3 contains the characterization results of the cured adhesives. The curing method used is described in the Test Methods.

[0265] Table 2A. Curable Composition (phr)

[0266]

[0267] Table 2B. Curable Compositions (wt%)

[0268]

[0269] Table 3. Test results

[0270]

[0271] NT = Not tested due to failure to cure and form a bond strong enough to test

Claims

1. A curable composition, comprising: a) (Meth) acrylic multi-block copolymers; b) statistical (meth) acrylic copolymers; c) Epoxy resin; d) a photoacid generator; and e) an ionic liquid having a melting point of less than 100 degrees Celsius and having a molecule selected from SbF6 - PF6 - or a mixture thereof.

2. The curable composition of claim 1, wherein the (meth)acrylic block copolymer is a triblock copolymer of formula ABA, wherein the A block is microphase separated from the B block, wherein the A block has a glass transition temperature equal to at least 50 degrees Celsius and the B block has a glass transition temperature equal to no more than 20 degrees Celsius as measured using dynamic mechanical analysis.

3. The curable composition according to claim 2, wherein each A block comprises a monomer unit derived from methyl methacrylate, and the B block comprises a monomer unit derived from n-butyl (meth)acrylate.

4. The curable composition according to any one of claims 1 to 3, wherein the curable composition comprises 10 wt% to 40 wt% of the (meth)acrylic block copolymer based on the total weight of the resin components in the curable composition.

5. The curable composition of any one of claims 1 to 4, wherein the statistical (meth)acrylic copolymer has a glass transition temperature of no more than 20 degrees Celsius when measured using dynamic mechanical analysis.

6. The curable composition according to any one of claims 1 to 5, wherein the statistical (meth)acrylate copolymer is crosslinked.

7. The curable composition according to any one of claims 1 to 6, wherein the curable composition comprises 20 to 60 wt% of the statistical (meth)acrylic copolymer based on the total weight of the resin components in the curable composition.

8. The curable composition of any one of claims 1 to 7, wherein the statistical (meth)acrylic copolymer is free or substantially free of monomer units derived from poly(alkylene oxide) (meth)acrylates having a number average molecular weight of at least 300 Daltons.

9. The curable composition of any one of claims 1 to 7, wherein the statistical (meth)acrylic copolymer further comprises monomer units derived from a poly(alkylene oxide) (meth)acrylate having a number average molecular weight of at least 300 Daltons.

10. The curable composition of claim 9, wherein the statistical (meth)acrylic copolymer comprises 1 to 40 wt% of monomer units derived from the poly(alkylene oxide) (meth)acrylate, based on the total weight of the statistical (meth)acrylic copolymer. 11 . The curable composition according to claim 1 , wherein the photoacid generator is an aryl-containing iodonium salt or a triarylsulfonium salt.

12. The curable composition according to any one of claims 1 to 11, wherein the ionic liquid is an ammonium salt of formula (VI), a sulfonium salt of formula (VII), an imidazolium salt of formula (VIII), a pyridinium salt of formula (IX), or a pyrrolidinium salt of formula (X) [N(R 20 )4] + X - (VI) [S(R 21 )3] + X - (VII) in Each R 20 , R 21 , R 22 , R 23 and R 24 are independently alkyl, hydroxy-substituted alkyl or a group of formula –(R 30 -O) y -R 31 An ether-containing group, wherein R 30 is an alkylene group, R 31 is an alkyl group, and y is an integer in the range of 1 to 10; and X - SbF6 - or PF6 - .

13. The curable composition according to any one of claims 1 to 12, wherein the curable composition comprises 10 to 40 wt% of a (meth)acrylic block copolymer; 20 to 60 wt% of said statistical (meth)acrylic copolymer; 10 to 50 wt % epoxy resin; 0.5 wt % to 5 wt % of a photoacid generator; as well as 1 to 20 wt% of an ionic liquid, Each amount is based on the total weight of the resin components in the curable composition.

14. A first product, comprising: The curable composition according to any one of claims 1 to 13, wherein the curable composition has a first surface and a second surface opposite to the first surface; as well as A first substrate or first release liner is positioned adjacent to the first surface of the first curable composition.

15. The first article of claim 14, wherein the first substrate is positioned adjacent to the first surface of the curable composition and a second release liner is positioned adjacent to the second surface of the curable composition.

16. The first product according to claim 14 or 15, wherein the curable composition alternates with the metal film, and the first product is arranged in the following order: first substrate or first release liner, curable composition, metal film and curable composition.

17. The first product according to any one of claims 14 to 16, wherein the first product is in the form of a roll.

18. The first article according to any one of claims 14 to 17, wherein the first article is a die cut suitable for adhering a first component to a second component.

19. A cured composition comprising the reaction product of the curable composition of any one of claims 1 to 13.

20. A second product, comprising: first base; Second base; as well as The cured composition of claim 19 positioned between the first substrate and the second substrate, wherein the first substrate is bonded to the second substrate with the first cured composition.

21. The second article of claim 20, wherein the cured composition alternates with the metal film, and the second article is arranged in the following order: first substrate or first release liner, cured composition, metal film, and cured composition.

22. The second product of claim 20, wherein the first substrate, the second substrate, or both are electrically conductive.

23. A method for separating the second article of claim 22, the method comprising applying a DC potential across the cured composition to separate the first substrate from the second substrate.

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