TECHNICAL FIELD

The present disclosure relates to an adhesive composition including a polymeric- based adhesive composition and a bio-based small molecule.

BACKGROUND ART

Adhesives are highly desirable in many applications, particularly for optical displays and electronics. However, at times it is desirable for adhesives to de -bond under certain conditions, such as applied heat. Such debondable adhesives are sought after as a means of recycling, material recovery, and quality assurance. There are several debondable on demand solutions on the market, however, none that are bio-based.

Accordingly, it would be desirable for an improved de-bondable adhesive that includes a bio-based material.

SUMMARY

Various aspects and embodiments contemplated herein may include, but are not limited to one or more of the following.

In a first aspect, an adhesive material includes a polymeric-based adhesive composition and a bio-based small molecule, wherein the bio-based small molecule has a degradation temperature of at least 100°C.

In a second aspect, a method of de-bonding an adhesive material includes: providing heat at a temperature of at least 100°C to an adhesive material including a polymeric -based adhesive composition and a bio-based small molecule, wherein the bio-based small molecule has a degradation temperature of at least 100°C.

In a third aspect, an optical stack includes an adhesive material according to the foregoing first aspect.

In a third aspect, an electronic device includes the adhesive material according to the foregoing first aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure may be better understood, and its numerous features and advantages made apparent to those skilled in the art by referencing the accompanying drawings.

FIG. 1 includes a graphical depiction of exemplary bio-based small molecules and their decomposition profiles. FIG. 2 includes a graphical depiction of exemplary bio-based small molecules and their decomposition profiles.

The use of the same reference symbols in different drawings indicates similar or identical items.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description in combination with the figures is provided to assist in understanding the teachings disclosed herein. The following discussion will focus on specific implementations and embodiments of the teachings. This focus is provided to assist in describing the teachings and should not be interpreted as a limitation on the scope or applicability of the teachings.

As used herein, the terms “comprises”, “comprising”, “includes”, “including”, “has”, “having” or any other variation thereof, are open-ended terms and should be interpreted to mean “including, but not limited to. . . .” These terms encompass the more restrictive terms “consisting essentially of’ and “consisting of.” In an embodiment, a method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive-or and not to an exclusive-or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

Also, the use of “a” or “an” is employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural, or vice versa, unless it is clear that it is meant otherwise. For example, when a single item is described herein, more than one item may be used in place of a single item. Similarly, where more than one item is described herein, a single item may be substituted for that more than one item.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The materials, methods, and examples are illustrative only and not intended to be limiting. To the extent not described herein, many details regarding specific materials and processing acts are conventional and may be found in reference books and other sources within the structural arts and corresponding manufacturing arts. Unless indicated otherwise, all measurements are at about 23°C +/- 5°C per ASTM, unless indicated otherwise. As described above, an adhesive material includes a polymeric -based adhesive composition and a bio-based small molecule. “Bio-based” includes any molecule derived from a biological source. In a particular embodiment, the bio-based small molecule has a degradation temperature of at least 100°C. In particular, the bio-based small molecule may include dehydration and decarboxylation additives incorporated into the polymeric-based adhesive base resin. The additives, in the cured adhesive, will degrade and release carbon dioxide (CO2) and/or water at an elevated temperature, such as 100°C or higher. This gas and/or water release causes a mechanical separation of the substrates, thereby decreasing the adhesive force of the base adhesive. In particular, a desirable drop in adhesion can be achieved.

The adhesive material is typically a composition that, when applied between two substrates and cured, provides adhesive strength between the two substrates. The adhesive material includes any polymeric-based adhesive composition envisioned. For instance, the polymeric-based adhesive composition includes an acrylic-based composition, a urethane- based composition, a silicone-based composition, an epoxy-based composition, or combination thereof. In an embodiment, the polymeric -based adhesive composition includes a pressure sensitive adhesive. In another embodiment, the polymeric-based adhesive composition includes a non-pressure sensitive adhesive. In a particular embodiment, the polymeric-based adhesive composition includes an acrylic-based composition. In a more particular embodiment, the polymeric -based adhesive composition consists essentially of an acrylic-based composition. As used herein, the phrase "consists essentially of" used in connection with the polymeric-based adhesive composition precludes the presence of monomers and polymers that affect the basic and novel characteristics of the polymeric-based adhesive composition, although, commonly used processing agents and additives such as, a filler, dye, pigment, compatibilizer, and any combination thereof may be used in the polymeric-based adhesive composition. In an embodiment, the polymeric-based adhesive composition consists of an acrylic -based composition.

The polymeric-based adhesive composition provides a matrix in which the bio-based small molecule is mixed therein. For instance, the bio-based small molecule is homogenously mixed in the polymeric -based adhesive composition. The bio-based small molecule typically includes a bio-based molecule having at least one carboxyl group, at least one hydroxyl group, or combination thereof. Typically, the bio-based molecule, when exposed to heat, releases a water molecule (H2O), a carbon dioxide molecule (CO2), or combination thereof. The mechanisms are dehydration and decarboxylation, respectively. “Bio-based small molecule” as used herein refers to a molecule derived from a biological source having an average molecular weight (Mw) of less than about 500 g/mol, such as less than about 400 g/mol, such as less than about 300 g/mol, such as less than about 250 g/mol, or even less than about 200 g/mol.

In an embodiment, the bio-based small molecule includes a malonic acid, a shikimic acid, a derivative thereof, or a combination thereof. In a more particular embodiment, the biobased small molecule includes a-ketoglutaric acid, phenylmalonic acid, butylmalonic acid, dimethylmalonic acid, methylmalonic acid, ethylmalonic acid, shikimic acid, inositol, quinic acid, saccharic acid, a derivative thereof, or combination thereof.

As discussed, the bio-based small molecule degrades via heat. Any heat source is envisioned and includes a thermal source, a microwave source, or combination thereof. Typically, the bio-based small molecule has a degradation temperature of at least 100°C, such as at least 150°C, such as at least 200°C, or even at least 250°C. Any amount of bio-based small molecule is present to provide de-bonding with applied heat. In an embodiment, the bio-based small molecule is present at an amount where it does not substantially affect the adhesion of the adhesive material when cured compared to an adhesive material that does not include any bio-based small molecule. “Substantially affect” as used herein refers to a loss in peel strength of less than 20%, such as 10%, such as 8%, or even 5%. In an embodiment, the bio-based small molecule is present at an amount of 0.001 weight % to 15 weight %, such as 0.5 weight % to 10 weight %, such as 2.5 weight % to 5 weight %, based on the total weight of the adhesive material. It will be appreciated that the amount of bio-based small molecule can be within a range between any of the minimum and maximum values noted above.

In an embodiment, the adhesive material consists essentially of the polymeric-based adhesive based composition and the bio-based molecule. As used herein, the phrase "consists essentially of" used in connection with the adhesive material precludes the presence of monomers and polymers that affect the basic and novel characteristics of the adhesive material, although, commonly used processing agents and additives such as a filler, dye, pigment, a compatibilizer, and any combination thereof may be used in the adhesive material. In another embodiment, the adhesive material consists of the polymeric -based adhesive based composition and the bio-based molecule.

In an embodiment, a method of de-bonding an adhesive material includes providing heat at a temperature of at least 100°C to an adhesive material including the polymeric -based adhesive composition and the bio-based small molecule. As heat is applied to the adhesive material, the bio-based small molecule either degrades via decarboxylation or dehydration. When this occurs, the adhesive material effectively de-bonds and loses its adhesive strength between two substrates. As such, the two substrates can be pulled apart, i.e. mechanically separated. For instance, the adhesive strength of the adhesive material decreases by at least 30%, at least 40%, at least 50%, at least 60%, or at least 70% when exposed to an elevated temperature, such as at a temperature of greater than 100°C, such as greater than 150°C, such as greater than 200°C, or even greater than 250°C.

Prior to any heat application to de-bond, the adhesive material, when cured, has an advantageous peel strength. In an embodiment, the adhesive material has a cohesive peel strength between the first substrate and a second substrate at a temperature of less than 100°C. For instance, “cohesive peel strength” means that the substrate fails before the adhesive bond fails. Any substrate is envisioned for the first substrate and the second substrate. In an embodiment, the first substrate and the second substrate may be the same material. In another embodiment, the first substrate and the second substrate are different materials. Exemplary materials for the substrate include, but are not limited to, a metal, a glass, a polymer, or combination thereof. Exemplary polymers include, but are not limited to, a polyester, a polyolefin, a polyimide, a polyamide, a polycarbonate, a reinforced plastic, or combination thereof.

The adhesive material including the polymeric-based adhesive composition and the bio-based small molecule can have at least one property selected from the following optical property group. In another embodiment, the adhesive material has at least two, at least three, or at least four properties selected from the following optical property group. The property group O refers predominately to optical properties and can include:

(i) an optical transparency of a film having a thickness of 25 micrometer (± 5 micrometer) of the adhesive material as determined by UV-Vis spectroscopy at 400 nm of at least 20%, at least 25%, at least 30%, at least 32%, at least 34%, at least 36%, at least 38%, at least 40%, at least 42%, or at least 44%;

(ii) an optical transparency of a film having a thickness of 25 micrometer (± 5 micrometer) of the adhesive material as determined by UV-Vis spectroscopy at 550 nm of at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 94%, or at least 96%;

(iii) an optical transparency of a film having a thickness of 25 micrometer (± 5 micrometer) of the adhesive material as determined by UV-Vis spectroscopy at 330 nm of not greater than 50%, not greater than 48%, not greater than 46%, not greater than 44%, not greater than 42%, not greater than 40%, not greater than 38%, not greater than 36%, not greater than 34%, not greater than 32%, not greater than 30%, not greater than 28%, not greater than 26%, not greater than 24%, not greater than 22%, not greater than 20%, not greater than 18%, or not greater than 16%;

(iv) a thickness retardation Rth of not more than 100 nm, not more than 80 nm, not more than 60 nm, not more than 50 nm, not more than 40 nm, not more than 30 nm, not more than 28 nm, not more than 26 nm, not more than 24 nm, not more than 22 nm, or not more than 20 nm;

(v) a Yellow Index according to ASTM E313 of a film having a thickness of 25 micrometer (± 5 micrometer) of the adhesive material of not more than 4.0, not more than 3.5, not more than 3.2, not more than 3.0, not more than 2.8, not more than 2.6, not more than 2.4, not more than 2.2, not more than 2.0, not more than 1.8, not more than 1.6, or not more than 1.4; or

(vi) a haze as determined according to ASTM D1OO3-13 of a film having a thickness of 25 micrometer (± 5 micrometer) of the adhesive material of not greater than 1.5%, not greater than 1.3%, not greater than 1.1%, not greater than 1.0%, not greater than 0.8%, not greater than 0.6%, not greater than 0.5%, not greater than 0.4%, or not greater than 0.3%.

Advantageously, the adhesive material may be used for any applications where the aforementioned adhesive and/or optical properties are desired. Adhesive films of any thickness are envisioned. In an embodiment, the film has a thickness of up to 150 microns. Adhesive films of the present invention can be applied in a broad spectrum of commercial industry ranging from the optical industry, electronic industry, computer industry, phone industry, automotive industry, telecommunication industry, films for the solar industry, and the like. For instance, an optical stack may include the adhesive material. In an example, the optical stack may include at least one film layer of the adhesive material. In an embodiment, an electronic device may include the adhesive material.

Many different aspects and embodiments are possible. Some of those aspects and embodiments are described herein. After reading this specification, skilled artisans will appreciate that those aspects and embodiments are only illustrative and do not limit the scope of the present invention. Embodiments may be in accordance with any one or more of the items as listed below.

Embodiment 1. An adhesive material including a polymeric -based adhesive composition and a bio-based small molecule, wherein the bio-based small molecule has a degradation temperature of at least 100°C. Embodiment 2. A method of de-bonding an adhesive material including: providing heat at a temperature of at least 100°C to an adhesive material including a polymeric -based adhesive composition and a bio-based small molecule, wherein the bio-based small molecule has a degradation temperature of at least 100°C.

Embodiment 3. The adhesive material or method of de-bonding the adhesive material in accordance with any of the preceding embodiments, wherein the polymeric-based adhesive composition includes an acrylic -based composition, a urethane-based composition, a silicone- based composition, an epoxy-based composition, or combination thereof.

Embodiment 4. The adhesive material or method of de-bonding the adhesive material in accordance with embodiment 3, wherein the polymeric -based adhesive composition consists essentially of an acrylic -based composition.

Embodiment 5. The adhesive material or method of de-bonding the adhesive material in accordance with any of the preceding embodiments, wherein the bio-based small molecule has an average molecular weight (Mw) of less than about 500 g/mol.

Embodiment 6. The adhesive material or method of de-bonding the adhesive material in accordance with any of the preceding embodiments, wherein the bio-based small molecule includes at least one carboxyl group, at least one hydroxyl group, or combination thereof.

Embodiment 7. The adhesive material or method of de-bonding the adhesive material in accordance with any of the preceding embodiments, wherein the bio-based small molecule includes a malonic acid, a shikimic acid, a derivative thereof, or a combination thereof.

Embodiment 8. The adhesive material or method of de-bonding the adhesive material in accordance with any of the preceding embodiments, wherein the bio-based small molecule includes a-ketoglutaric acid, phenylmalonic acid, butylmalonic acid, dimethylmalonic acid, methylmalonic acid, ethylmalonic acid, shikimic acid, inositol, quinic acid, saccharic acid, a derivative thereof, or combination thereof.

Embodiment 9. The adhesive material or method of de-bonding the adhesive material in accordance with any of the preceding embodiments, wherein the bio-based small molecule has a degradation temperature of at least 150°C, such as at least 200°C, or even at least 250°C.

Embodiment 10. The adhesive material or method of de-bonding the adhesive material in accordance with any of the preceding embodiments, wherein the bio-based small molecule is present at an amount of 0.001 weight % to 15 weight %, such as 0.5 weight % to 10 weight %, such as 2.5 weight % to 5 weight %, based on the total weight of the adhesive material. Embodiment 11. The adhesive material or method of de-bonding the adhesive material in accordance with any of the preceding embodiments, wherein the adhesive material has a cohesive peel strength between a first substrate and a second substrate at a temperature of less than 100°C.

Embodiment 12. The adhesive material or method of de-bonding the adhesive material in accordance with embodiment 11, wherein the first substrate, the second substrate, or combination thereof includes a metal, a glass, a polymer, or combination thereof.

Embodiment 13. The adhesive material or method of de-bonding the adhesive material in accordance with embodiment 12, wherein the polymer includes a polyester, a polyolefin, a polyimide, a polyamide, a polycarbonate, a reinforced plastic, or combination thereof.

Embodiment 14. The adhesive material or method of de-bonding the adhesive material in accordance with any of the preceding embodiments, wherein the adhesive strength of the adhesive material decreases by at least 30%, at least 40%, at least 50%, at least 60%, or at least 70% at a temperature of greater than 100°C.

Embodiment 15. The adhesive material or method of de-bonding the adhesive material in accordance with any of the preceding embodiments, wherein the adhesive material includes at least one of the following optical properties: (i) an optical transparency of a film having a thickness of 25 micrometer (± 5 micrometer) of the adhesive material as determined by UV-Vis spectroscopy at 400 nm of at least 20%, at least 25%, at least 30%, at least 32%, at least 34%, at least 36%, at least 38%, at least 40%, at least 42%, or at least 44%;

(ii) an optical transparency of a film having a thickness of 25 micrometer (± 5 micrometer) of the adhesive material as determined by UV-Vis spectroscopy at 550 nm of at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 94%, or at least 96%;

(iii) an optical transparency of a film having a thickness of 25 micrometer (± 5 micrometer) of the adhesive material as determined by UV-Vis spectroscopy at 330 nm of not greater than 50%, not greater than 48%, not greater than 46%, not greater than 44%, not greater than 42%, not greater than 40%, not greater than 38%, not greater than 36%, not greater than 34%, not greater than 32%, not greater than 30%, not greater than 28%, not greater than 26%, not greater than 24%, not greater than 22%, not greater than 20%, not greater than 18%, or not greater than 16%; (iv) has a haze as determined according to ASTM D1OO3-13 of a film having a thickness of 25 micrometer (± 5 micrometer) of the polyimide material of not greater than 1.5%, not greater than 1.3%, not greater than 1.1%, not greater than 1.0%, not greater than 0.8%, not greater than 0.6%, not greater than 0.5%, not greater than 0.4%, or not greater than 0.3%; or (v) a Yellow Index according to ASTM E313 of a film having a thickness of 25 micrometer (± 5 micrometer) of the adhesive material of not more than 4.0, not more than 3.5, not more than 3.2, not more than 3.0, not more than 2.8, not more than 2.6, not more than 2.4, not more than 2.2, not more than 2.0, not more than 1.8, not more than 1.6, or not more than 1.4.

Embodiment 16. The adhesive material or method of de-bonding the adhesive material in accordance with embodiment 15, having at least two, at least three, or at least four properties of the optical properties.

Embodiment 17. The method of de-bonding the adhesive material in accordance with embodiments 2-16, wherein the heat is provided via a thermal source, a microwave source, or combination thereof.

Embodiment 18. An article comprising a first substrate, a second substrate, and an adhesive material disposed between the first and second substrates, the adhesive material including a polymeric-based adhesive composition and a bio-based small molecule, wherein the bio-based small molecule has a degradation temperature of at least 100°C.

Embodiment 19. The article in accordance with embodiment 18, wherein the first substrate, the second substrate, or combination thereof includes a metal, a glass, a polymer, or combination thereof.

Embodiment 20. The article in accordance with embodiment 19, wherein the polymer includes a polyester, a polyolefin, a polyimide, a polyamide, a polycarbonate, a reinforced plastic, or combination thereof.

Embodiment 21. The article in accordance with embodiment 18, wherein the polymeric-based adhesive composition includes an acrylic-based composition, a urethane- based composition, a silicone-based composition, an epoxy-based composition or combination thereof.

Embodiment 22. The article in accordance with embodiment 21, wherein the adhesive-based composition consists essentially of an acrylic -based composition.

Embodiment 23. The article in accordance with any of embodiments 18 through 22, wherein the bio-based small molecule has an average molecular weight (Mw) of less than about 500 g/mol.

Embodiment 24. The article in accordance with any of embodiments 18 through 23, wherein the bio-based small molecule includes at least one carboxyl group, at least one hydroxyl group, or combination thereof. Embodiment 25. The article in accordance with any of embodiments 18 through 24, wherein the bio-based small molecule includes a malonic acid, a shikimic acid, a derivative thereof, or a combination thereof.

Embodiment 26. The article in accordance with any of embodiments 18 through 25, wherein the bio-based small molecule includes a-ketoglutaric acid, phenylmalonic acid, butylmalonic acid, dimethylmalonic acid, methylmalonic acid, ethylmalonic acid, shikimic acid, inositol, quinic acid, saccharic acid, a derivative thereof, or combination thereof.

Embodiment 27. An optical stack comprising the adhesive material in accordance with embodiments 1 and 3 through 16.

Embodiment 28. An electronic device including the adhesive material in accordance with embodiments 1 and 3 through 16.

The following examples are provided to better disclose and teach processes and compositions of the present invention. They are for illustrative purposes only, and it must be acknowledged that minor variations and changes can be made without materially affecting the spirit and scope of the invention as recited in the claims that follow.

EXAMPLES

Bio-based small molecules according to the present disclosure are tested for their decomposition profile. Initial screening of these molecules was performed on the TGA to determine the exact decomposition profile of each molecule. In each case a sharp single discrete mass loss was sought after with as low a char yield as possible. This behavior was desirable because it provides an indication of how much potential gas would be released and how quickly. For this debondable process, a rapid, massive, and predictable mass loss is desired to provide the best mechanical debondable behavior where the released gases physically force the bonded materials apart and thereby decreasing the adhesive forces. The debonding behavior also desirable should take place in a relatively tight temperature window as to avoid undesirable debonding behavior. Results can be seen in Figures 1 and 2 and Tables 1 and 2. Table 1

Table 2

The primary molecule targeted for the dehydration approach, shikimic acid, has an onset of 238°C and also results in a high char yield at 300°C. Given that shikimic acid has a high temperature of decomposition, temperatures close to 250°C will most likely be needed to successfully carry out the dehydration reaction.

Solubility Testing

After initial TGA screens all subsequent molecules were then subjected to solubility evaluations in representative solvents (ethyl acetate, methanol, ethanol, & water) and P200 (base pressure sensitive acrylic-based adhesive resin) at a variety of loadings 0.5 - 15 wt%. Two classes of compounds resulted from this testing, species that were soluble in ethyl acetate (phenylmalonic acid, butylmalonic acid, dimethylmalonic acid, methylmalonic acid, alpha-ketoglutaric acid, & ethylmalonic acid) and species that were water soluble (shikimic acid, quinic acid, & myo-Inositol).

Table 3

The five malonic acid species were then evaluated in neat P200 and the water soluble species were evaluated with P200 spiked with 200 proof ethanol or methanol at additive loadings ranging from 0.5 - 15 wt%. Each additive resin was incorporated as follows into the P200 benchmark PSA:

Base PSA resin - Thermally curable OCA resin: P200 (pressure sensitive acrylicbased adhesive) and crosslinker (X-500)

The supplies

Vial, disposable pipette, balance, mixer, release liner, applicator, ovens (40°C, 70°C and 100°C), roller, PET or polarizer, glass substrate

Procedure for creating OCA sample -

Substrates - glass substrate and PET film

Control samples included a P200 resin with no additives:

1. Set oven temperature (40°C, 70°C and 100°C).

2. Prepare OCA resin: P-200:X-500 = 100:0.22 then mix.

3. Prepare release liner to coat.

4. Coat.

5. Dry - 5min at 40°C then 10 min at 70°C. 6. Laminate onto PET or Polarizer with the roller. Laminate from the bottom to the top with the roller then measure the thickness from the top, middle and bottom.

7. Cut the OCA film laminated on PET or polarizer then anneal to vaporize all solvent residue and moisture captured; Put glass substrate and the OCA film the release liner is peeled off into the oven (100°C) then anneal at least for 1 hr.

8. Finally, making the sample to measure peel strength; Lamination is the same as process 6.

Samples with bio-reachables (P200 resin WITH additives)

This lamination and sample preparation process was used consistently for each sample tested; the only variables changed were additive utilized, loading, and if a compatibilizer was utilized, such as 200 proof ethanol to insure additive incorporation.

Debonding

Samples with varying loading levels of the bio-reachable additives were generated to test their ability to debond on demand. Debonding evaluation was then performed via two methods, a convection oven and a 900 Watt Microwave.

Convection Oven

In the convection oven the laminated samples were tested at several temperatures 70°C, 105°C, 130°C, 160°C, & 200°C (200°C was found to begin degrading the PET backing film). Under each temperature condition the samples were held at temperature for 10 minutes, then evaluated visually for bubble formation and peel tested on an Inston to evaluate the peel strength in reference to a control (P200 &X-500).

Below is a representative example of desired debonding behavior as shown by ethylmalonic acid as the additive. Before debonding the ethylmalonic acid samples were translucent and demonstrated no major visual change at the lower testing temperatures, 105°C & 130°C, and significant bubble formation at 160°C.

2.5 wt% Ethylmalonic Acid Convection Oven:

Table 4

Additives tested via convection oven and their ability to result in a debondable on demand system (Debonding / No Debonding):

Table 5 Microwave Oven (630 Watts)

In the microwave oven evaluation, each sample was tested for 6 min at 70% power.

This time and power gave roughly the same temperatures seen in the 160°C convection oven evaluations as monitored via an infrared (IR) temperature gun. Each sample was then evaluated for bubble formation and degradation of the PET substrate. Below is a table of panels before and after debonding in a microwave oven, utilizing ethylmalonic acid. In contrast to the convection oven, the microwave provides a more inconsistent heating across the sample creating more erratic void formation, but overall similar results to oven testing, 10 min at 160°C.

2.5 wt% Ethylmalonic Acid Microwave Evaluation:

Table 6 Additives tested via microwave oven and their ability to result in a debondable on demand system (Debonding / No Debonding): Table 7

Malonic acid derivatives performance: Table 8 captures the different additives tested, their loading levels, and their performance when exposed to different temperatures.

Table 8

• C - cohesive / A - Adhesive / x - No or <50%change in adhesion / ✓ - 50% > loss in adhesion Testing was also performed on shikimic acid which required the addition of either ethanol or methanol to solubilize into P200. This addition of methanol/ethanol also caused a significant hazing to the overall solution and the resulting panels. These systems were tested mainly in the convection oven and showed limited success. Shikimic acid showed little to no visible debonding behavior (bubble formation). Of the materials tested, all species of malonic acid showed debondability apart from phenylmalonic acid which did not show debonding up to 200°C in the convection oven or the microwave oven, at which point the PET substrate began to fail before the adhesive debonded. However, two malonic acid derivatives showed notably better debondable behavior, butylmalonic acid and ethylmalonic acid. Both additives showed a consistent and predictable debonding gas release, ethylmalonic acid demonstrated release between 130°C - 160°C depending on length of exposure to heat source in the convection oven and butylmalonic acid demonstrated release at 160°C. Both additives caused a reduction in peel strength of about half dropping from roughly 40 N/25mm to 20 N/25mm. Additionally, both ethyl and butyl malonic acid operated similarly in the microwave evaluation showing similar drops in adhesion of about 50% of the baseline adhesion.

The shikimic acid derivatives required the addition of a solvent to allow incorporation of these species into the P200. Shikimic acid was found to produce a hazy adhesive film and upon heating produced no noticeable debondable behavior.

Note that not all of the activities described above in the general description or the examples are required, that a portion of a specific activity may not be required, and that one or more further activities may be performed in addition to those described. Still further, the order in which activities are listed are not necessarily the order in which they are performed.

In the foregoing specification, the concepts have been described with reference to specific embodiments. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of invention.

Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any feature(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature of any or all the claims.

After reading the specification, skilled artisans will appreciate that certain features are, for clarity, described herein in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any subcombination. Further, references to values stated in ranges include each and every value within that range.