WO2021225778A1 - Résines adhésives sensibles à la pression, thermofusibles, acryliques, réticulables par rayonnement, présentant un photodurcissement par les uva amélioré - Google Patents

Résines adhésives sensibles à la pression, thermofusibles, acryliques, réticulables par rayonnement, présentant un photodurcissement par les uva amélioré Download PDF

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WO2021225778A1
WO2021225778A1 PCT/US2021/028065 US2021028065W WO2021225778A1 WO 2021225778 A1 WO2021225778 A1 WO 2021225778A1 US 2021028065 W US2021028065 W US 2021028065W WO 2021225778 A1 WO2021225778 A1 WO 2021225778A1
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meth
acrylate
photocrosslinker
pressure sensitive
acrylate polymer
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PCT/US2021/028065
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English (en)
Inventor
Laxmisha SRIDHAR
Bahram Issari
Zhan YANG
Wenhua Zhang
Mark Jason
Mohammadreza NASIRI
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Henkel IP & Holding GmbH
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Publication of WO2021225778A1 publication Critical patent/WO2021225778A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • C09J7/381—Pressure-sensitive adhesives [PSA] based on macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
    • C09J7/385—Acrylic polymers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F2/00—Processes of polymerisation
    • C08F2/46—Polymerisation initiated by wave energy or particle radiation
    • C08F2/48—Polymerisation initiated by wave energy or particle radiation by ultraviolet or visible light
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/10—Esters
    • C08F220/12—Esters of monohydric alcohols or phenols
    • C08F220/16—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms
    • C08F220/18—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms with acrylic or methacrylic acids
    • C08F220/1804—C4-(meth)acrylate, e.g. butyl (meth)acrylate, isobutyl (meth)acrylate or tert-butyl (meth)acrylate
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • C09J133/02—Homopolymers or copolymers of acids; Metal or ammonium salts thereof
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2433/00—Presence of (meth)acrylic polymer

Definitions

  • This present disclosure relates generally to hot melt pressure sensitive adhesives, and more particularly to such adhesives having improved ultraviolet A (UVA) photo cure.
  • UVA ultraviolet A
  • PSA Pressure sensitive adhesives
  • UV curable ultraviolet curable
  • Polyacrylates possess a variety of advantages over other adhesives because they are highly stable toward UV light, oxygen, and ozone which are found in abundance in the environment.
  • synthetic and natural rubber adhesives normally contain double bonds, which make these adhesives unstable to the aforementioned environmental effects.
  • Further advantages of polyacrylates include their transparency and their serviceability within a relatively wide temperature range.
  • Polyacrylate PSAs can be prepared in solvent by solution free radical polymerization of (meth)acrylic monomers and/or derivatives thereof and the resulting polymers are then applied to a substrate from a solution, typically using a coating bar. After application the solvent is removed and the adhesive is dried on the substrate.
  • Cohesive strength of an adhesive refers to the bond strength between the molecules of the adhesive while adhesive strength refers to the bond strength between the adhesive and a substrate.
  • the polymer is often crosslinked to a limited degree. Crosslinking or curing is done by exposure to either a thermal source or a UV source.
  • This solvent process for formation of PSAs described is fairly costly and, as a general rule, the solvent is not recycled resulting in the high consumption of organic solvents and a high environmental burden. Moreover, it is very difficult to produce PSA tapes with a high adhesive application rate without also producing bubbles in the adhesive layer.
  • One remedy is to create hot melt PSAs and to use a hot melt process to apply the PSA to a substrate.
  • Hot melt pressure sensitive adhesives are thermoplastic compositions that combine the processing advantage of hot melt adhesives and the properties of pressure sensitive adhesives.
  • Hot melt pressure sensitive adhesives are solids at room temperature, melt at elevated temperatures, and are applied to a substrate in molten form. They regain their solid form on cooling to form a tacky solid coating on the substrate. Exposing the solidified composition to actinic radiation partially crosslinks that composition into a PSA.
  • Hot melt pressure sensitive adhesives typically do not contain water or any solvents. These compositions are commonly applied to various substrates, such as paper, fabric, metal, and plastic films that, after exposure to actinic radiation, are converted into a large number of different pressure sensitive adhesive products such as pressure sensitive adhesive tapes and labels.
  • HMPSA products have a broad fields of application, for example in the automobile industry for fastening or sealing, in the pharmaceutical industry for bandages or transdermal drug delivery systems, in the packaging industry for sealing, bonding or labeling.
  • Very low molecular weight acrylate polymers, without crosslinking, will yield hot melt pressure sensitive adhesives with sufficient fluidity when in molten form, however the resulting adhesives lack cohesive strength.
  • Very high molecular weight acrylate polymers, without crosslinking, give better cohesive strength, however these are often too viscous at the common hot melt application temperatures of from 175 F to 356 F to be usable in commercial applications.
  • a commercially useable hot melt pressure sensitive adhesive requires balancing these two competing issues.
  • hot melt pressure sensitive adhesive compositions can comprise an acrylic polymer with various functional groups that will act as a photocrosslinker in the hot melt pressure sensitive adhesive composition.
  • the composition When exposed to actinic radiation the composition undergoes a controlled crosslinking reaction.
  • the molten hot melt PSA is not crosslinked and has a lower viscosity usable in commercial applications and the applied PSA has increased cohesion after exposure to actinic radiation and crosslinking.
  • the use of medium pressure mercury bulbs to crosslink PSAs has several problems associated with it.
  • the medium pressure mercury bulbs utilize a large amount of energy during the crosslinked process, they have a relatively short life of 1,000 hours, they tend to be large and they generate heat and ozone during use.
  • the LED lights run cooler, are smaller, do not generate ozone during use and have an effective life in the range of 10,000 hours. LED lights produce radiation in the range of 365 nm and above.
  • One aspect of the present disclosure is a photocrosslinker having the structure shown below that is responsive to LED light at 365 nm and above Formula I wherein: R is H, a Ci to C30 alkyl, a Ci to C30 alkoxy, Ci to C30 acyloxy a C3 to C30 aryloxy, a halogen or a Ci to C30 thioether; Ri is H or CH3.
  • X is optional. When X is not present the benzophenone is connected to the terminal (meth)acrylate functionality by the methylene bridge and R is not H.
  • X is present and can comprise a Ci to C30 acyclic linear or branched alkyl group or oxy alkyl group.
  • X is present and the photocrosslinker can comprise the structure shown below wherein: BP is the benzophenone unit of Formula I, which is bonded through the methylene bridge to X, the terminal (meth)acrylate is shown on the right hand side, and Y is a Ci to C30 acyclic linear or branched alkyl group or oxyalkyl group.
  • X is present and can comprise a polyester made from a ring opening polymerization of a lactone or lactide using benzophenone methylol as the ring opening initiator followed by (meth)acrylation of the terminal hydroxyl group.
  • X is present and can comprise a fused ring structure forming a photocrosslinker having the structure as shown below wherein: BP is the benzophenone unit of Formula I, which is bonded through the methylene bridge to X, the terminal (meth)acrylate is shown on the right hand side, and the fused ring is a C3 to C30 cycloaliphatic, heterocyclic, aromatic or heteroaromatic.
  • Another aspect of the present disclosure is to provide a radiation curable (meth)acrylate polymer comprising the reaction products of: one or more monomers selected from the group consisting of a (meth)acrylate, an alkyl(meth)acrylate, a hydroxyalkyl(meth)acrylate, acetoacetoxy ethyl acrylate and mixtures thereof; and a photocrosslinker having a structure as defined in Formula I below: Formula I wherein:
  • R is H, a Ci to C30 alkyl, a Ci to C30 alkoxy, Ci to C30 acyloxy a C3 to C30 aryloxy, a halogen or a Ci to C30 thioether;
  • Ri is H or CH ;
  • X is optional and is as described previously. When X is not present the benzophenone is connected to the terminal (meth)acrylate functionality by the methylene bridge and R can be H.
  • the (meth)acrylate polymer is curable by exposure to LED light emitting a wavelength of 365 nm or higher.
  • Another aspect of the present disclosure is to provide a hot melt pressure sensitive adhesive comprising a (meth)acrylate polymer as described above.
  • Another aspect of the present disclosure is to provide a substrate having a coating comprising from 10 to 1000 g/meter 2 of the hot melt pressure sensitive adhesive as described above.
  • FIG. 1 is a graph showing the size exclusion chromatography of a series of pressure sensitive adhesive acrylate polymers
  • FIG. 2 is a graph showing the increase in storage modulus versus time of exposure to an LED light for the pressure sensitive adhesive acrylate polymers A, 1 and Duro- Tak UV4606;
  • FIG. 3 is a graph showing the increase in storage modulus versus time of exposure to an LED light for the pressure sensitive adhesive acrylate polymers B, 2 and Duro- Tak UV4606;
  • FIG. 4 a graph showing the increase in storage modulus versus time following exposure to an LED light for the pressure sensitive adhesive acrylate polymers B, 2 and Duro- Tak UV4606 and following exposure to a Hg light source for 1 and Duro-Tak UV4606; and [00030]
  • FIG. 5 A shows one embodiment of the photocrosslinker according to the present disclosure incorporated into an acrylate polymer backbone when X is not present
  • FIG. 5B shows another embodiment of the photocrosslinker according to the present disclosure incorporated into an acrylate polymer backbone when X is present.
  • first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly and expressly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
  • the disclosed compounds include any and all isomers and stereoisomers.
  • the disclosed materials and processes may be alternately formulated to comprise, consist of, or consist essentially of, any appropriate components, moieties or steps herein disclosed.
  • the disclosed materials and processes may additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any components, materials, ingredients, adjuvants, moieties, species and steps used in the prior art compositions or that are otherwise not necessary to the achievement of the function and/or objective of the present disclosure.
  • Hot melt pressure sensitive adhesive HMPSA
  • pressure sensitive adhesive PSA
  • (meth)acrylate refers to both acrylate and methacrylate monomers and derivatives thereof; and the term acrylate polymer is meant to refer in general to polymers or copolymers formed from polymerization reaction of one or more (meth)acrylate monomers unless otherwise noted.
  • alkyl or “alkane” means a saturated, acyclic, linear or branched chain hydrocarbon group.
  • Non-limiting, exemplary alkanes include methyl, ethyl, n-propyl, isopropyl, isobutyl, n-butyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, isohexyl and decyl.
  • An “alkoxy” refers to an alkyl group singularly bonded to an oxygen while an “aryloxy” refers to an aryl group singularly bonded to an oxygen.
  • the term “pressure sensitive adhesive” means a viscoelastic material which adheres instantaneously to most substrates with the application of slight pressure and remains permanently tacky.
  • a “tackifier” means any composition which is useful to impart tack to the hot melt pressure sensitive adhesive composition.
  • the photocrosslinker according to the present disclosure is directly polymerizable into the acrylate polymer backbone of the HMPSA composition. It forms a pendant benzophenone group linked through a methylene linkage to a terminal (meth)acrylate which is incorporated into the acrylate polymer backbone of the composition. The crosslinking of acrylate polymers in the PSA composition occurs through the benzophenone functionality.
  • One aspect of the present disclosure is a photocrosslinker having the structure shown below in Formula I, this photocrosslinker is surprisingly responsive to LED light at 365 nm and above.
  • An essential feature of this photocrosslinker according to Formula I is the presence of at least the methylene bridge structure between the benzophenone and the terminal (meth)acrylate. The presence of X is optional as described further below; however the methylene bridge is essential.
  • R is H, a Ci to C30 alkyl, a Ci to C30 alkoxy, Ci to C 30 acyloxy a C 3 to C 30 aryloxy, a halogen or a Ci to C 30 thioether.
  • Ri is H or CH .
  • X is optional and when not present the benzophenone is connected to the (meth)acrylate functionality by the methylene bridge and R is not H.
  • X can be present and the photocrosslinker can comprise the structure shown wherein: BP is the benzophenone unit of Formula I, shown below which is bonded through the methylene bridge to X, the terminal (meth)acrylate is shown on the right hand side, and Y is a Ci to C30 alkyl or alkoxy;
  • X when present, can comprise a Ci to C30 alkyl or alkoxy
  • X when present, can comprise a polyester made from a ring opening polymerization of a lactone or lactide using benzophenone methylol as the ring opening initiator followed by (meth)acrylation of the terminal hydroxyl group; or
  • X when present, can comprise a fused ring structure to form a photocrosslinker having the structure as shown below wherein: wherein, BP is the benzophenone unit of Formula I which is bonded through the methylene bridge to X, a C3 to C30 cycloaliphatic, heterocyclic, aromatic or heteroaromatic, and the terminal (meth)acrylate is shown on the right hand side.
  • BP is the benzophenone unit of Formula I which is bonded through the methylene bridge to X, a C3 to C30 cycloaliphatic, heterocyclic, aromatic or heteroaromatic, and the terminal (meth)acrylate is shown on the right hand side.
  • the photocrosslinker has the structure shown in Formula I wherein X is not present, R is H, a Ci to C30 alkyl, a Ci to C30 alkoxy, a C3 to C30 aryloxy, a halogen or a Ci to C30 thioether; Ri is H or CFP; and the methylene bridge has an orientation that is either Ortho or Meta but not Para. In this embodiment it is preferable that when X is not present the methylene bridge has an orientation of Ortho or Meta and not Para.
  • the synthesis of the photocrosslinker can begin with 3-Chloromethylbenzophenone instead of 4-(bromomethyl)benzophenone as described in the examples below.
  • the photocrosslinker is present in an amount of 0.01 to 5.0 mole % in the acrylate polymer backbone, more preferably in an amount of 0.1 to 0.5 mole % based on total moles of all components in the polymer.
  • the photocrosslinker comprises 4-methylenebenzophenone acrylate (MBP-Acr). It can be synthesized as described below.
  • MBP-Acr 4-methylenebenzophenone acrylate
  • the photocrosslinker of the present disclosure is directly polymerized into the acrylate polymer backbone by solution radical polymerization as described herein and as shown in FIG. 5A and 5B.
  • FIG.5A is the photocrosslinker wherein X is not present and FIG. 5B shows the acrylate backbone structure wherein X is present.
  • the result is a curable polyacrylate polymer comprising pendant and/or terminal photocrosslinker moieties bonded thereto.
  • the polyacrylate polymer crosslinks into a pressure sensitive adhesive.
  • the photocrosslinker is referred to as pendant whether it is internally located in the polymer backbone or terminally located in the polymer backbone.
  • the ketyl radicals instead participate in termination by a coupling reaction which produces pinacol as shown.
  • the aminomethyl radical generated from the coinitiator initiates polymerization of the acrylate monomer, in the article the system was used to polymerize the monomer 1,6-hexanediol diacrylate (HDD A).
  • HDD A monomer 1,6-hexanediol diacrylate
  • the HMPSA composition according to the present disclosure comprises at least one acrylate polymer having pendant from its backbone the disclosed photocrosslinker in the amounts described above.
  • the photocrosslinker is incorporated into the acrylate polymer backbone by virtue of the (meth)acrylate function in the photocrosslinker structure.
  • the acrylate polymers can be homopolymers or copolymers and are formed from monomers comprising one or more of (meth)acrylate monomer, alkyl(meth)acrylate monomer, hydroxyalkyl(meth)acrylate monomer, acetoacetoxyethyl methacrylate (AAEM) and mixtures thereof.
  • the other (meth)acrylate monomers include acrylic acid and methacrylic acid monomer.
  • alkyl(meth)acrylate monomers include methyl (meth)acrylate, ethyl (meth)acrylate, 2 ethylhexyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate.
  • the PSA composition can comprise any mixture of acrylate polymers according to the present disclosure, meaning it can be formed from a mixture of two or more acrylate polymers according to the present disclosure.
  • the acrylate polymers are made by solution radical polymerization and have a Mn, number average molecular weight, range of from 1 X 10 3 to 1 X 10 6 , more preferably from 5 X 10 4 to 5 X 10 5 .
  • the acrylate polymers have a Mw, weight averaged molecular weight, of from 1 X 10 3 to 1 X 10 6 and more preferably from 5 X 10 4 to 5 X 10 5 .
  • the acrylate polymers have a polydispersity (Mw/Mn) of from 4 to 6, more preferably from 4.4 to 5.5.
  • the total amount of all acrylate polymers in the PSA composition is preferably from 10 to 100% based on total PSA composition weight [00052]
  • the HMPSA composition according to the present disclosure can also comprise a tackifier to increase their bonding characteristics to low energy surfaces such polyethylene or polypropylene surfaces.
  • the most commonly used tackifiers in acrylate polymer based pressure sensitive adhesives include rosin esters, terpene phenols, esters of hydrogenated rosins, synthetic hydrocarbons and combinations thereof.
  • Preferred tackifiers are esters of hydrogenated rosins as they exhibit high levels of tack, oxidation resistance, and limited interference with UV radiation used in post polymerization crosslinking.
  • three examples of suitable tackifiers are Foral ® 85 and Foral ® 105, available from Pinova ® and Pensel GA-100, available from Arakawa.
  • the Foral ® 85 tackifier is described by Pinova ® as a thermoplastic resin that is a glycerol ester of highly hydrogenated refined wood resin.
  • the Foral ® 105 tackifier is described by Pinova ® as a thermoplastic resin that is a pentaerythritol ester of highly hydrogenated refined wood resin.
  • Tackifiers are typically added at levels from 0-60 parts per 100 parts acrylate polymer with a preferred range of 10-40 parts per 100 parts acrylate polymer. It should be noted that the addition of tackifiers can have undesirable effects such as raising the glass transition temperature (T g ) of the system and reducing the cohesive strength.
  • T g glass transition temperature
  • the tackifiers listed above are useful for tackifying the acrylate polymers of this disclosure. The particular tackifying resin and/or the amounts used will depend upon the acrylic polymer composition.
  • the HMPSAs can optionally include one or more other additives and combinations of additives.
  • the optional additives include, by way of example: photosynergists, ultraviolet absorbers, hindered amine light stabilizers, adhesion promoters, defoamers, flame retardants, surfactants, fillers, plasticizers, flow aids, wetting aids, rheology modifiers, dyes, pigments, nucleating agents, antioxidants, and combinations thereof.
  • the additives may be used a widely variable levels ranging, per additive, at from 0.05 to 50% by weight based on the total polymer weight.
  • the HMPSA composition according to the present disclosure has the following characteristics. It is a self-supporting solid at standard temperature of 25° C. It has a melting temperature below 90° C and maintains a stable viscosity at 90° C for at least 24 hours. A stable viscosity means that the viscosity at 90° C does not increase from its initial viscosity by more than 30% over a 24 period when held at 90° C.
  • the HMPSA composition can be dissolved in a solvent, coated onto a substrate and subjected to UVA exposure to form a crosslinked PSA layer, however this is not the preferred commercial use or method of formation.
  • the HMPSA composition is not dissolved in a solvent, instead it is heated to approximately 90° C and applied to a substrate.
  • the applied composition is then exposed to actinic radiation for a period of time and at an intensity sufficient to induce crosslinking of the acrylate polymers through the pendant benzophenone functionalities.
  • a release layer is applied over the crosslinked PSA and the coated substrate is stored until further processed or use.
  • the actinic radiation used is from a LED light source at a wavelength of 365 nm or higher.
  • the time of exposure to the LED light source is from 0.01 seconds to 60 minutes, more preferably for less than 5 seconds and most preferably for less than 1 second.
  • the exposure is preferably at an intensity level of 0.1 W/cm 2 of greater at a distance from the light source of from 1 to 300 millimeters.
  • the HMPSA according to the present disclosure can be applied to wide range of backing substrates as is known in the art.
  • the backing substrate can comprise a tape, a label, paper, fabric, metal, plastic films, foams, foils, glass, natural rubber, synthetic rubber, wood, plywood and other substrates.
  • these substrates are coated with the PSA composition at a level of from 10 to 1000 grams/meter 2 .
  • the molten PSA can be applied onto the substrate in a number of ways known in art such as by roller, slot orifice, spray, draw down bar or extrusion.
  • These PSA coated substrates have a broad range of applications. In the automotive industry they are used in sealing and fastening applications. In the medical and pharmaceutical industry they are used in bandages, gauze wraps, surgical tapes, and transdermal drug delivery systems. In the mailing and packaging industry they are used for sealing, bonding and labeling. They are also use in a wide variety of tape and label formats.
  • One example of a photocrosslinker according to the present disclosure is 4- methylenebenzophenone acrylate (MBP-Acr), synthesized as described below, using the reaction shown in Scheme 1 below.
  • MBP-Acr 4- methylenebenzophenone acrylate
  • the general process for preparing the (meth)acrylate polymers is as follows.
  • the (meth) acrylate monomers used were «-butyl acrylate (BA) and acrylic acid (AA) and the amounts used to form the various PSA compositions are given below in Table 1.
  • Samples 1 and 2 are in accordance with the present disclosure.
  • Samples A and B are comparative examples and not in accordance with the present disclosure.
  • the Samples in TABLE 1 were prepared as follows.
  • the resultant polymers were analyzed by size exclusion chromatography and the results are shown in FIG. 1 and key features are tabulated in TABLE 2 below.
  • the resultant polymers are relatively uniform in size range, have a relatively low standard deviation and a polydispersity index (PDI) of from 4.5 to 5.1.
  • PDI polydispersity index
  • the improved shear strength of polymers made using the novel photocrosslinker is due to that photocrosslinker and is not due to any increase in polymer molecular weight or polymer configuration.
  • the rheometer testing conditions were 80° C, 300 mW/cm 2 of UVA from a LED light source emitting UVA light at 365 nm and above, parallel plate with 8mm diameter, 0.1% strain, 10 rads/s and 200 micron gap.
  • the bottom plate is quartz and the top plate is metal.
  • the sample is exposed to radiation through the bottom plate.
  • Samples 1, A and a commercially available pressure sensitive adhesive, Duro- Tak UV4606 from Henkel Corporation, were tested.
  • Duro-Tak UV4606 does not include a photocrosslinker in accordance with the present disclosure.
  • Sample 1 comprises 0.1 mole % of the novel MBP-Acr photocrosslinker.
  • Sample A is not in accordance with the present disclosure and includes 0.1 mole % of commercially available photocrosslinker V6976. UV exposure started at about 8 minutes and continued until about 15 minutes. The results are shown in FIG. 2. The results show that when the compositions are exposed to UV radiation from the LED light there is an immediate and rapid increase in storage modulus of all the Samples that nearly reaches its peak value after about 13-15 minutes. In addition, one can see that inventive Sample 1 significantly outperforms comparative Sample A. This shows the surprising effect of including the methylene bridge between the benzophenone and the terminal methacrylate. In addition, Sample 1 also significantly outperforms the Duro-Tak UV4606 Sample (“UV4606 ” in the figures).
  • the Duro-Tak UV4606 Sample outperforms the comparative Sample A.
  • Sample 2 comprises 0.21 mole % of the inventive photocrosslinker MBP-Acr.
  • Comparative Sample B comprises 0.21 mole % of the commercially available photocrosslinker V6976.
  • the results show that when the compositions are exposed to UV radiation there is a rapid increase in storage modulus of all the Samples that nearly reaches its peak value after about 13-15 minutes.
  • Sample 2 in accordance with the present disclosure significantly outperforms comparative Sample B. This shows the surprising effect of including the methylene bridge between the benzophenone and the terminal methacrylate.
  • Sample 2 also significantly outperforms the Duro-Tak UV4606 Sample, reaching more than twice as high a level of storage modulus. Comparing FIG. 2 to FIG. 3 one can also see that it requires twice the level, 0.21 mole %, of the photocrosslinker V6976 to increase the storage modulus to the same extent as is seen with only 0.1 mole % of the novel photoinitator according to the present disclosure. Comparing the results of Samples 1 and B, which are nearly identical, Sample 1 has a faster rise initially but the Samples eventually reach approximately the same storage modulus level with Sample 1 a bit higher. Again these results show the dramatic and unexpected improvement attributable to the novel photocrosslinker according to the present disclosure.
  • FIG. 4 shows the results of the same test on Samples 1, A and Duro-Tak UV4606.
  • Each Sample was tested using UV radiation from the above LED lamp.
  • Samples 1 and Duro-Tak UV4606 were also tested separately using radiation from an Omnicure S2000 mercury lamp.
  • the rheometer testing conditions were 80° C, 300 mW/cm 2 of UVA from the LED light source or 125 mW/cm 2 of UVA from the mercury lamp source, with other conditions remaining as previously described.
  • inventive Sample 1 significantly outperforms comparative Samples A and Duro-Tak UV4606 under the same exposure conditions.
  • Sample 1 also dramatically outperforms the Duro-Tak UV4606 following exposure to a Hg lamp source.
  • PSA cohesion strength tends to increase with increasing physical or chemical crosslinks.
  • Physical crosslinks are generally associated with entanglement density, which increases with increasing molecular weight.
  • the present compositions rely on chemical crosslinks and do not rely on physical high molecular weight.
  • Chemical crosslinks are the result of the reactivity and proximity of the novel pendant photocrosslinkers and intra/interchain moieties with extractable hydrogen. With slower line speed, or longer exposure time/ higher dosage, more of the pendant photocrosslinkers are excited for longer time, resulting in more chemical crosslinks and a better shear holding time. However, the shear strength will degrade if the sample is overcured.
  • the photoinitator according to the present disclosure is directly incorporated into the backbone of the acrylate polymer and thus is pendant from the same. This allows for a cross linking reaction between pendant benzophenones on adjacent polymers and greatly improved performance.
  • the photocrosslinker according to the present disclosure is highly responsive to LED light at 365 nm and above at commercially viable rates. Thus it will not only offer improved performance but will also allow the commercial use of LED curing lamps with their attendant advantages and lower costs.

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  • Adhesives Or Adhesive Processes (AREA)

Abstract

L'invention concerne un agent de photoréticulation sensible aux ultraviolets, ayant une structure telle que définie dans la Formule I ci-dessous : dans laquelle : R représente H ou un groupe alkyle en C1 à C30, alcoxy en C1 à C30, acyloxy en C1 à C30, aryloxy en C3 à C30, halogéno ou thioéther en C1 à C30 ; R1 représente H ou CH3 ; et X est facultatif, R ne représentant pas H lorsque X n'est pas présent. En outre, l'invention concerne un adhésif sensible à la pression, thermofusible, comprenant un polymère de (méth)acrylate dans lequel est incorporé l'agent de photoréticulation répondant à la Formule I. L'agent de photoréticulation est sensible à la lumière ultraviolette provenant d'une source de lumière à DEL ayant une longueur d'onde supérieure ou égale à 365 nm.
PCT/US2021/028065 2020-05-05 2021-04-20 Résines adhésives sensibles à la pression, thermofusibles, acryliques, réticulables par rayonnement, présentant un photodurcissement par les uva amélioré WO2021225778A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1727320A (zh) * 2005-02-03 2006-02-01 常州华钛化学有限公司 反应型二苯甲酮光引发剂及其制备方法
CN103012665A (zh) * 2012-12-26 2013-04-03 河北智生环保科技有限公司 一种紫外光交联的有机硅改性丙烯酸酯共聚物乳液
KR20170101339A (ko) * 2016-02-26 2017-09-06 주식회사 엘지화학 광학 점착제용 (메타)아크릴레이트기 함유 벤조페논의 제조방법 및 광학 점착제 조성물
US20180037775A1 (en) * 2015-04-13 2018-02-08 3M Innovative Properties Company Method of Preparing Crosslinked Pressure-Sensitive Adhesives Using a Light-Emitting Diode for Crosslinking

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1727320A (zh) * 2005-02-03 2006-02-01 常州华钛化学有限公司 反应型二苯甲酮光引发剂及其制备方法
CN103012665A (zh) * 2012-12-26 2013-04-03 河北智生环保科技有限公司 一种紫外光交联的有机硅改性丙烯酸酯共聚物乳液
US20180037775A1 (en) * 2015-04-13 2018-02-08 3M Innovative Properties Company Method of Preparing Crosslinked Pressure-Sensitive Adhesives Using a Light-Emitting Diode for Crosslinking
KR20170101339A (ko) * 2016-02-26 2017-09-06 주식회사 엘지화학 광학 점착제용 (메타)아크릴레이트기 함유 벤조페논의 제조방법 및 광학 점착제 조성물

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
TANG YUNHUI, ZHANG YUXUAN, YANG JINLIANG, NIE JUN: "Synthesis and characteristics of photopolymerized benzophenone", JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY, JOHN WILEY & SONS, INC., US, vol. 55, no. 2, 15 January 2017 (2017-01-15), US , pages 313 - 320, XP055863484, ISSN: 0887-624X, DOI: 10.1002/pola.28386 *

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