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US-12617974-B2 - Partable laminate and method for parting long-term structural bonds

US12617974B2US 12617974 B2US12617974 B2US 12617974B2US-12617974-B2

Abstract

Laminates separated after long-term bonding and methods for separating laminates after long-term bonding is provided. The laminates comprise (a) a first adhesive layer, (b) a separation layer, and (c) a second adhesive layer, wherein the separation layer comprises a laser-sensitive pigment which at the same time is coloring, and so preferably a black coloration is produced, and consists of a cured coating material, preferably an electron beam-cured or UV-cured coating material, which is at least partly removable by laser irradiation. The first adhesive layer and/or the second adhesive layer may be laser beam-translucent or may comprise a reactive or latent-reactive adhesive.

Inventors

  • PHILIPP PREUSS
  • Arne Koops

Assignees

  • TESA SE

Dates

Publication Date
20260505
Application Date
20230303
Priority Date
20220304

Claims (18)

  1. 1 . A laminate configured to be separated after long-term bonding, the laminate comprising: a) a first adhesive layer; b) a separation layer; and c) a second adhesive layer, wherein the separation layer comprises a laser-sensitive pigment which at the same time is coloring, a cured coating material which is at least partly removable by laser irradiation, the first adhesive layer and/or the second adhesive layer is laser beam-translucent, the first adhesive layer or the second adhesive layer comprises, or the first adhesive layer and the second adhesive layer comprise, a reactive or latent-reactive adhesive, and the cured coating material of the separation layer comprises a cured acrylate coating material composition comprising: 30 to 80 wt % of a trifunctional oligomer A comprising three unsaturated (meth)acrylate units per molecule, with a number-average molecular weight Mn (determined by gel permeation chromatography (GPC) of between 1000 and 5000 g/mol, 0 to 20 wt % of a trifunctional monomer B contains three unsaturated (meth)acrylate units per molecule and in one preferred embodiment of the disclosure has a molecular weight Mn of between 300 to 1000 g/mol, 1 to 30 wt % of a difunctional monomer C comprising a monomer having two unsaturated acrylate units per molecule and a molecular weight Mn of between 100 to 1000 g/mol, and 2 to 40 wt % of a coloring pigment.
  2. 2 . The laminate according to claim 1 , wherein the laser-sensitive pigment is admixed in an amount of 1 wt % up to not more than 40 wt %, based on a total weight of the coating material layer.
  3. 3 . The laminate according to claim 1 , wherein the laser-sensitive pigment comprises carbon black or titanium dioxide.
  4. 4 . The laminate according to claim 3 , wherein when carbon black is present as the laser-sensitive pigment, the carbon black is used at 2 to 7 wt %.
  5. 5 . The laminate according to claim 3 , wherein when titanium dioxide is present as the laser-sensitive pigment, the titanium dioxide is used at 15 to 40 wt %.
  6. 6 . The laminate according to claim 1 , wherein the separation layer is applied in a thickness of 0.5 to 100 μm.
  7. 7 . The laminate according to claim 1 , wherein the separation layer consists of a single coating material layer.
  8. 8 . The laminate according to claim 1 , wherein at least one adhesive layer of the first and second adhesive layers contains at least 40 wt % of one or more poly(meth)acrylates.
  9. 9 . The laminate according to claim 1 , wherein one adhesive layer of the first and second adhesive layers is a pressure sensitive adhesive comprising at least the following two components: at 60 wt % to 90 wt %, in the adhesive, a first polymer component based on polyacrylate or a polyacrylate component; and at 10 wt % to 40 wt %, in the adhesive, a second polymer component, substantially immiscible with the polyacrylate component, based on elastomer, more particularly on a synthetic rubber or an elastomer component.
  10. 10 . The laminate according to claim 1 , wherein the first adhesive layer comprises a reactive or latent-reactive adhesive and the second adhesive layer comprises a reactive or latent-reactive adhesive or a pressure sensitive adhesive.
  11. 11 . The laminate according to claim 10 , wherein the first adhesive layer consists of the reactive or latent-reactive adhesive and the second adhesive layer consists of the reactive or latent-reactive adhesive or the pressure sensitive adhesive.
  12. 12 . The laminate according to claim 11 , wherein the first adhesive layer consists of the reactive or latent-reactive adhesive and the second adhesive layer consists of the pressure sensitive adhesive.
  13. 13 . A method for parting a long-term structural bond produced by means of the laminate according to claim 1 , wherein at least part of the area of the separation layer is removed by means of laser irradiation and the film laminate is separated into a first part-laminate and a second part-laminate.
  14. 14 . The method according to claim 13 , wherein forces are applied to at least one of the part-laminates that increase the spacing of the two part-laminates from one another.
  15. 15 . The method according to claim 13 , wherein an infrared laser is used for the laser irradiation.
  16. 16 . The method according to claim 13 , wherein the whole area of the separation layer is removed.
  17. 17 . A method comprising: long-term structurally bonding at least two components together with the laminate according to claim 1 .
  18. 18 . The method according to claim 17 , wherein the at least two components are at least two automotive industry components or at least two electronics industry components.

Description

The present disclosure relates to a laminate designed and equipped to be separated after long-term bonding, comprising a first layer of adhesive, a separation layer, and a second layer of adhesive. The present disclosure further encompasses a method for parting a long-term structural bond produced by means of such a laminate. In repair shops and in the end-of-life recycling of electronic devices, the desire to be able to repair electronic devices or else automobiles, or to be able as extensively as possible to disassemble and/or recycle them, is gaining in importance for not just environmental reasons but also economic reasons. There are different kinds of electronic devices here, differing in their recyclability and also in the degree of recycling: large household appliances (also called white goods): for example, washing machines, refrigerators and freezers, ovens;small household appliances (likewise included as white goods): for example, vacuum cleaners, coffee machines, microwaves;information technology and communication devices: for example, computers, monitors, printers, cell phones, telephones;consumer electronic devices (also called brown goods): for example, televisions, video recorders, digital cameras. Electrical and electronic devices in particular contain a multiplicity of substances and materials. If used electrical and electronic devices are disposed of improperly, such as via the household garbage, for example, environmental risks may arise from the pollutants they still contain in some cases. As well as pollutants such as heavy metals and HCFCs, however, used electrical and electronic devices also contain a range of valuable substances, which should be recovered and therefore recirculated. Where, conversely, used electrical and electronic devices are disposed of properly, it is possible to replace primary raw materials (and hence their costly and laborious extraction) and to make a substantial contribution to the preservation of the natural resources. In order to be able to achieve these objectives, there are specific obligations imposed on all relevant actors (manufacturers, trade, municipalities, owners, waste managers) in Germany by the law governing the sale, return, and environmentally sound disposal of electrical and electronic equipment (Electrical and Electronic Equipment Law—ElektroG) in implementation of Directive 2012/19/EU concerning waste electrical and electronic equipment (WEEE). By avoiding waste, through reasonable tests for possibilities of preparation for the re-use of entire devices or individual components, and by requirements regarding the more extensive recovery of value from wastes, the aim is to achieve a substantial contribution to preserving natural resources and to reducing pollutant emissions. Corresponding recycling-friendly designs are needed which enable on-demand disassembly (“debonding on demand”). The recycling-friendly designs include repartable adhesive bonds. The reason is that, in small electronic devices in particular, there is a very sharply increasing trend toward adhesively bonding parts, usually on a long-term basis, rather than connecting them in a way which can be undone mechanically. Film laminates in the form of double-sided adhesive tapes are employed, for example, for bonding two components to one another. In general the intention is for these components to be bonded to one another on a long-term basis by such a film laminate. This is intended to result in a correspondingly long life and durability of the bond and/or the product. Examples of components joined to one another in this way are touch panels of the kind employed in computer screens or mobile electronic devices. If one of the two components is damaged, it is completely impossible, or possibly only on application of substantial resource (force), to separate the bonded assembly again in order to replace a component. There is also the risk of the component that is not damaged suffering damage in the course of the separation. DE 10 2020 209 557 A1 discloses a film laminate designed and equipped to be separated after long-term bonding, comprising the following layers: a first layer of pressure sensitive adhesive,a separation layer,a second layer of pressure sensitive adhesive, where the separation layer has a thickness of 40 nm to 500 nm, the first layer of pressure sensitive adhesive is laser beam-translucent, and the separation layer consists of a metal which is at least partly removable by laser irradiation. In this case a metal is removed by laser, leading to the separation. Translucency is the partial light transmissiveness of a body. The word derives from the Latin lux for light. Wax, the human skin, leaves, and many other substances are translucent, since they transmit light partially, but are not transparent. In delimitation from transparency, translucency may be described as light transmissiveness. The reciprocal property to translucency is opacity. Hence where a substance pos