阅读说明：本技术 包含聚烯烃共聚物添加剂的聚异丁烯粘合剂 (Polyisobutylene adhesives comprising polyolefin copolymer additives ) 是由 瓦萨瓦·萨尼 大卫·T·阿莫斯 贾森·D·克拉珀 约翰·W·麦克阿里斯特 陈中 皮埃尔·比 于 2019-02-26 设计创作，主要内容包括：本发明描述了一种粘合剂组合物和制品。所述粘合剂组合物包含聚异丁烯聚合物组分；至多20重量％的聚烯烃共聚物,所述聚烯烃共聚物包含酸性单体的聚合单元；以及任选地,至少一种增粘剂。所述聚烯烃共聚物通常包含C<Sub>2</Sub>-C<Sub>4</Sub>烷亚基单元。所述聚烯烃共聚物包含羧酸或其不饱和衍生物的聚合单元。在一些实施方案中,所述聚烯烃共聚物具有在50℃至150℃范围内的熔融温度。在一些实施方案中,所述聚烯烃共聚物具有小于40mgKOH/g、35mgKOH/g、30mgKOH/g或25mgKOH/g的酸值。(An adhesive composition and article are described. The adhesive composition comprises a polyisobutylene polymer component; up to 20 weight percent of a polyolefin copolymer comprising polymerized units of an acidic monomer; and optionally, at least one tackifier. The polyolefin copolymer typically comprises C 2 ‑C 4 An alkylidene unit. The polyolefin copolymer comprises polymerized units of a carboxylic acid or an unsaturated derivative thereof. In some embodiments, the polyolefin copolymer has a melting temperature in the range of 50 ℃ to 150 ℃. In thatIn some embodiments, the polyolefin copolymer has an acid number of less than 40, 35, 30, or 25 mgKOH/g.)

1. An adhesive composition, comprising:

a polyisobutylene polymer component; and

up to 20 weight percent of a polyolefin copolymer comprising polymerized units of an acidic monomer;

optionally, at least one tackifier.

2. The adhesive composition of claim 1, wherein the polyolefin copolymer comprises at least 75, 80, 85, 90, or 95 weight percent polymerized units of a polyolefin.

3. The adhesive composition of claims 1-2, wherein the polyolefin copolymer comprises C₂-C₄Polymerized units of an alkylidene group.

4. The adhesive composition of claims 1-3 wherein the polyolefin copolymer comprises polymerized units of a carboxylic acid or an unsaturated derivative thereof.

5. The adhesive composition of claims 1-4 wherein the carboxylic acid derivative is an anhydride.

6. The adhesive composition of claims 1-5, wherein the polyolefin copolymer has a melting temperature in the range of 50 ℃ to 150 ℃.

7. The adhesive composition of claims 1-6, wherein the polyolefin copolymer has an acid value of less than 40, 35, 30, or 25 mgKOH/g.

8. The adhesive composition of claims 1-7, wherein the polyolefin copolymer further comprises polymerized units of at least one (meth) acryloyl monomer.

9. The adhesive composition of claims 1-8, wherein the adhesive composition comprises less than 10 wt% polymerized units of one or more (meth) acryloyl monomers.

10. The adhesive composition of claims 1-9, wherein the polyisobutylene polymer component comprises an unfunctionalized polyisobutylene polymer.

11. The adhesive composition of claims 1-10, wherein the polyolefin copolymer is not covalently bonded to the polyisobutylene polymer component.

12. The adhesive composition of claims 1-11, wherein the polyisobutylene polymer component has an average weight average molecular weight in the range of 150,000 to 500,000 grams/mole.

13. The adhesive composition of claims 1-12 wherein the polyisobutylene polymer component comprises a first polyisobutylene polymer having a weight average molecular weight of no greater than 150,000 g/mole and a second polyisobutylene polymer having a weight average molecular weight of greater than 300,000 g/mole.

14. The adhesive composition of any one of the preceding claims, wherein the tackifier is a non-hydrogenated or hydrogenated aliphatic hydrocarbon tackifier.

15. The adhesive composition of any one of the preceding claims, wherein the composition further comprises a UV blocker.

16. The adhesive composition of any one of the preceding claims, wherein the adhesive composition has a haze of less than 10% at a thickness of 20 microns.

17. The adhesive composition of any one of the preceding claims, wherein the adhesive composition has less than 100g/m at a thickness of 20 microns when measured at 40 ℃ and a relative humidity gradient of 90%²WVTR/day.

18. An article comprising the adhesive composition of any one of the preceding claims, wherein the adhesive composition is disposed on a substrate.

19. The article of claim 18 wherein the adhesive composition has a thickness of adhesive of from 0.001mm to 1 mm.

20. The article of claim 18 or 19, wherein one or more of the substrates is a release liner.

21. The article of claims 18-20, wherein the composition is disposed between two substrates.

22. The article of claims 18-21, wherein one or more of the substrates is an optical film, a display unit, a touch sensor, or a lens.

Background

Many types of input devices are currently available for performing operations in electronic systems, such as buttons, keys, mice, touch panels, touch screens, and the like. Touch screens, in particular, are becoming increasingly popular because of their intuitive appeal and ease of operation. Touch screens can allow a user to perform various functions by touching the touch sensor panel. To manufacture these devices, silver nanowires, metal mesh (e.g., Cu, Ag halide), Indium Tin Oxide (ITO) alternatives are increasingly being utilized. non-ITO based conductive films have low resistance relative to ITO transparent electrodes, which have high resistance problems in large touch applications.

Even with lower electrical resistance and cheaper manufacturing costs, it is well known that metal-based materials are susceptible to electrochemical oxidation with oxidants such as oxygen and moisture. Oxidation and electromigration between silver or copper traces will lead to connectivity problems in the conductive traces when under current and high temperature/humidity environments (i.e., 65 ℃ and 90% humidity). In fact, metal migration between traces can cause so-called dendrite growth and bridging between traces, which eventually shorts out the circuit. In contrast, corrosion can damage the traces, and thus the current passing therethrough.

Organic Light Emitting Diodes (OLEDs) are increasingly used in displays and light sources due to their lower power consumption, higher response speed and excellent space utilization. OLED elements are very sensitive to moisture or oxygen. The organic light emitting material easily loses its self-luminescence upon exposure to moisture, and a highly reactive cathode having a low work function is easily corroded by moisture and oxygen.

Disclosure of Invention

While various adhesive compositions have been developed that are suitable for use in electronic devices, the industry would find advantage in adhesive compositions that exhibit improved properties.

In one embodiment, an adhesive composition is described that includes a polyisobutylene polymer component; up to 20 weight percent of a polyolefin copolymer comprising polymerized units of an acidic monomer; and optionally, at least one tackifier.

The polyolefin copolymer typically comprises C₂-C₄An alkylidene unit. The polyolefin copolymer comprises polymerized units of a carboxylic acid or an unsaturated derivative thereof. In some embodiments, the polyolefin copolymer has a melting temperature in the range of 50 ℃ to 150 ℃. In some embodiments, the polyolefin copolymer has an acid number of less than 40, 35, 30, or 25 mgKOH/g. The adhesive composition may exhibit improved adhesion, particularly to metal substrates. The adhesive composition preferably has low haze and/or low moisture vapor transmission.

In another embodiment, an article is described comprising the adhesive composition described herein disposed on a substrate or disposed between two substrates. In some embodiments, one or more of the substrates is an optical film, a display unit, a touch sensor, or a lens.

Drawings

Figure 1 is a top view of a sample configuration for a patterned ITO polyester film resistance change measurement.

The figures are not drawn to scale and are intended for illustrative purposes only.

Detailed Description

To protect touch sensors and OLEDs in electronic devices, a low Water Vapor Transmission Rate (WVTR), low water content, and low dielectric constant (Dk) adhesive or optically clear adhesive (e.g., OCA) is described that can be directly integrated into an electronic device to protect the sensor and display from moisture, temperature, foreign substances, or chemical permeation. The adhesive or OCA has low Water Vapor Transmission Rate (WVTR), low water content, low dielectric constant (Dk), and optional Ultraviolet (UV) blocking characteristics. Even at low WVTR and low water content, the adhesive or OCA retains its optical quality during durability testing, i.e., it retains high visible light transmission and low haze. The OCA can be advantageously used in the visible region of the touch sensor panel because it maintains high visible light transmittance and low haze. In addition, the OCAs described herein provide good compliance, impart corrosion protection, and provide flow characteristics to cover sensor traces, Flexible Printed Circuits (FPCs), and any display cover ink stairs.

An adhesive composition comprising a polyisobutylene polymer component is described herein. The polyisobutylene polymer component comprises one or more polyisobutylene polymers. Such polyisobutylene polymers may be homopolymers and/or copolymers. As used herein, "polyisobutylene polymer" refers to both homopolymers and copolymers, unless otherwise specified.

In some embodiments, the adhesive composition is a pressure sensitive adhesive.

Pressure sensitive adhesives are typically characterized by a frequency of 1Hz at the application temperature (typically room temperature (e.g., 2)5 deg.C)) has a molecular weight of less than 3 × 10⁵Pa (0.3 MPa.) storage modulus (G '), as used herein, storage modulus (G ') refers to a value obtained using Dynamic Mechanical Analysis (DMA) according to the test method described in U.S. patent application Ser. No. 62/479,527, filed 3.31.2017.A pressure sensitive adhesive composition, in some embodiments, has a storage modulus (G ') of less than 2 ×⁵Pa、1×10⁵Pa、9×10⁴Pa、8×10⁴Pa、7×10⁴Pa、6×10⁴Pa、5×10⁴Pa、4×10⁴Pa or 3 × 10⁴Pa, in some embodiments, the composition has a storage modulus of at least 2.0 × 10⁴Pa or 2.5 × 10⁴Pa, storage modulus (G').

Generally, pressure sensitive adhesives are characterized by having a glass transition temperature "Tg" of less than 25 ℃; while other adhesives may have a Tg of 25 ℃ or higher, typically ranging up to 50 ℃. As used herein, Tg refers to the value obtained with DMA according to the test method described in the examples. In some embodiments, the pressure sensitive adhesive composition has a Tg of no greater than 20 ℃, 15 ℃, 10 ℃,5 ℃,0 ℃, or-5 ℃. The Tg of the pressure sensitive adhesive is typically at least-40 ℃, -35 ℃, -30 ℃, -25 ℃ or-20 ℃.

Generally, pressure sensitive adhesives are characterized by adequate adhesion. In some embodiments, the peel adhesion (e.g., to aluminum) measured according to the test methods described in the examples is at least 0.1N/dm, 0.5N/dm, 1N/dm, 2N/dm, 3N/dm, 4N/dm, or 5N/dm, ranging up to, for example, 15N/dm, 16N/dm, 17N/dm, 18N/dm, 19N/dm, or 20N/dm or more.

In some embodiments, the polyisobutylene polymer component comprises a polyisobutylene polymer comprising at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 mole percent polymerized units of isobutylene.

In other embodiments, the polyisobutylene polymer component comprises a polyisobutylene copolymer comprising at least 50, 55, or 60 mole percent polymerized units of polyisobutylene. In some embodiments, the copolymer further comprises polymerized units derived from 1-butene and/or 2-butene. The polymerized units derived from 1-butene and/or 2-butene are typically present in an amount of at least 1, 5, 10, 15, or 20 mole percent of the polyisobutylene copolymer in a range of up to 30, 35, 40, 45, or 50 weight percent. Polyisobutylene copolymers that also contain polymerized units derived from 1-butene and/or 2-butene may be characterized as "polybutenes".

The polyisobutylene polymer component may comprise at least two polymers, where a first polyisobutylene polymer comprises a higher concentration of polymerized units derived from 1-butene and/or 2-butene than a second polyisobutylene polymer.

Other examples of polyisobutylene copolymers include copolymers of isobutylene and isoprene, copolymers of isobutylene and butadiene, and halogenated butyl rubbers obtained by brominating or chlorinating these copolymers. However, the polyisobutylene copolymer may be free of halogenated butyl rubber, with the halogen (e.g., chloride, bromide) content being less than 1, 0.5, 0.25, 0.1, 0.01, or 0.001 mole percent of the polyisobutylene polymer.

Polyisobutylene copolymers generally do not contain structural units derived from styrene. Furthermore, the polyisobutylene copolymers are typically random copolymers. One or more such features distinguish the polyisobutylene copolymer from the styrene isobutylene block copolymer component.

Thus, depending on the selection of the one or more polyisobutylene polymers, the polyisobutylene polymer component comprises at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or more polymerized units of polyisobutylene.

The one or more polyisobutylene polymers may contain trace amounts of C8-C28 oligomers. The concentration of such oligomers is typically less than 0.15, 0.10, or 0.05 weight percent based on the total weight of the polyisobutylene polymer.

It is to be understood that the one or more polyisobutylene polymers may have a very low concentration of reactive double bonds or other functional groups remaining from the polymerization process in which the polyisobutylene polymer is prepared. The concentration of such reactive double bonds or other functional groups is typically less than 5 mole%, 4 mole%, 3 mole%, or 2 mole%.

The polyisobutylene polymer or polymers typically have a density of 0.92 g/cc. However, the density may be 0.91 or less depending on the content of 1-butene and/or 2-butene and/or one or more other olefin comonomers. In addition, the glass transition temperature of such polymers, as measured by Differential Scanning Calorimetry (DSC), is typically in the range of-64 ℃ to-65 ℃. The polyisobutylene polymer or polymers are typically cold-flowing at room temperature.

Polyisobutylene polymers are commercially available from several manufacturers. Homopolymers are commercially available, for example, from BASF Corp (Florham Park, n.j.) of Florham Park, n.j., under the trade designation OPPANOL (e.g., OPPANOL B12, B15, B30, B50, B80, B100, B150, and B200). These polymers typically have a weight average molecular weight in the range of about 40,000 to 1,000,000 grams/mole or greater. Other polyisobutylene polymers are commercially available in a wide range of molecular weights from United Chemical Products (UCP), st. petersburg, Russia; under the trade name VISTA NEX^TMCommercially available from Exxon chemical Company; and commercially available under the trade designation "Hycar" from b.f. goodrich (b.f. goodrich). Such polyisobutylene polymers are characterized as unfunctionalized polyisobutylene polymers that are free of functional groups such as amines, imides, and anhydrides.

In some embodiments, the adhesive composition contains little or no polyisobutylene polymer with functional groups. Thus, the concentration of the one or more functionalized polyisobutylene polymers is typically less than 1 weight percent of the adhesive composition. In this embodiment, the polyolefin copolymer is not covalently bonded to the polyisobutylene polymer component.

In some embodiments, the polyisobutylene component further comprises a polyisobutylene having a functional groupAn olefinic polymer. Various functionalized PIB materials are commercially available. For example, a polyisobutylene amine having a number average molecular weight (Mn) of about 1,000 g/mole and a molar mass distribution Mw/Mn of 1.6 may be available under the trade designation "Kerocom^TMPIBA03 "is commercially available from BASF Corporation (Florham Park, n.j.) of freholm Park, new jersey. In addition, polyisobutylene succinimides are available under the trade designation "Kerocom^TMPIBSI "was purchased from BASF corporation. Anhydride-terminated polyisobutylene having (Mn) about 1,000 g/mole is available from BASF under the trade designation "Glissopal SA". Such materials may optionally be present in the adhesive composition at concentrations within the following ranges: 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 wt% of the adhesive composition, ranging up to 40 wt%. Depending on the functional group, the polyolefin copolymer may or may not be covalently bonded to the functionalized polyisobutylene polymer.

In typical embodiments, the polyisobutylene component comprises a blend of two or more polyisobutylene polymers, wherein each polyisobutylene polymer has a different weight average molecular weight (Mw). As used herein, all weight average molecular weights are based on Gel Permeation Chromatography (GPC) using polystyrene standards according to the test method described in U.S. patent application serial No. 62/479,527, filed 2017, 3, 31.

For example, in some embodiments, the polyisobutylene component comprises a blend of a higher molecular weight polyisobutylene polymer (i.e., Mw greater than 300,000 g/mole) and a medium molecular weight polyisobutylene polymer (i.e., Mw less than 150,000 g/mole or 100,000 g/mole).

When the polyisobutylene component comprises two or more polyisobutylene polymers, the average weight average molecular weight of the component can be estimated by the following values: the average molecular weight of each polyisobutylene polymer is multiplied by the weight fraction of each polyisobutylene polymer in the polyisobutylene component and then summed. For example, if the polyisobutylene component contains about 64 wt% of a first polyisobutylene polymer having a weight average molecular weight of 75,000 and about 36 wt% of a second polyisobutylene polymer having a weight average molecular weight of 750,000 grams/mole, the average weight average molecular weight may be estimated to be 75,000 x 0.64+750,000 x 0.36-318,000 grams/mole. Thus, in some embodiments, the polyisobutylene polymer component may comprise one or more polyisobutylene polymers such that the average weight average molecular weight (Mw) of the polyisobutylene polymer component is at least 150,000 grams/mole, 200,000 grams/mole, or 250,000 grams/mole, and ranges up to 400,000 grams/mole; 450,000 g/mole to 500,000 g/mole. More than one low molecular weight PIB and more than one high molecular weight can be used.

In some embodiments, the intermediate molecular weight amount is equal to or greater than the high molecular weight amount based on the total weight of the polyisobutylene component. For example, the intermediate molecular weight amount can be at least 50, 55, 60, 65, 70, or 75 weight percent of the polyisobutylene component. In this embodiment, the higher molecular weight amount may be at least 25, 30, 35, 40, 45, or 50 weight percent of the polyisobutylene component.

The adhesive or OCA typically comprises at least 40 wt.%, 45 wt.%, or 50 wt.% of the polyisobutylene component. In some advantageous embodiments, the adhesive or OCA comprises at least 55 wt%, 60 wt%, 65 wt%, 70 wt%, or 75 wt% polyisobutylene component. The polyisobutylene polymer component provides desirable Water Vapor Transmission Rate (WVTR) characteristics. In some embodiments, the 51 micron adhesive layer has a WVTR of less than 20 grams per square meter per day (g/sq.m/day) or 15 g/sq.m/day or 10 g/sq.m/day at 40 ℃ and 90% relative humidity gradient. In other words, the WVTR of the adhesive per micron thickness may be at least 0.2 g/sq.m/day, 0.25 g/sq.m/day, 0.3 g/sq.m/day, 0.35 g/sq.m/day, or 0.4 g/sq.m/day. In other embodiments, a 20 micron adhesive layer has a WVTR of less than 100g/m at 40 ℃ and a relative humidity gradient²75 g/m/day²Daily, 50g/m²25 g/m/day²Day, 20g/m²Daily or 15g/m²The day is.

The combination of a medium molecular weight PIB resin and a high molecular weight PIB resin is particularly advantageous because the combination provides a wide range of desirable characteristics. Medium molecular weight PIB facilitates processing during hot melt extrusion by reducing the melt viscosity of the compounded adhesive mixture. In solvent processing, a medium molecular weight facilitates faster diffusion of the solvent during drying, thereby enabling thicker coatings to be formed. Moreover, the intermediate molecular weight PIB imparts conformability to the OCA, which enables ink step coverage and proper wetting on different surfaces, which are key features of the OCA. The high molecular weight gives cohesion to the adhesive system, which improves adhesion, shear strength, tensile strength, room temperature and high temperature dimensional stability. These properties are critical to OCA, and different applications may require a wide range of compositions to accommodate the specific characteristics of each specific application.

The adhesive or OCA further comprises a polyolefin copolymer. The polyolefin copolymer is generally miscible with the polyisobutylene component so that a combination of improved adhesion and low haze can be achieved.

In some embodiments, the polyolefin of the copolymer may be obtained by copolymerizing ethylene or α -olefin using a Ziegler-Natta catalyst or a metallocene catalyst as the polymerization catalyst₂-C₄Polymerized units of an alkylidene group. In some embodiments, the polyolefin comprises polypropylene and the polyolefin may be characterized by propylene-based random copolymers, such as ethylene-propylene copolymers, propylene-butene copolymers, and ethylene-propylene-butene copolymers. In some embodiments, the polyolefin copolymer comprises at least 60, 70, or 80 mole percent propylene, based on the total polyolefin copolymer.

In some embodiments, the polyolefin of the copolymer has at least 10,000 g/mole; 20,000 g/mole; 30,000 g/mole; 40,000 g/mole; or a weight average molecular weight of 50,000 g/mole. The polyolefin of the copolymer typically has a weight average molecular weight of no greater than 500,000 g/mole; 400,000 g/mole; 300,000 g/mole or 200,000 g/mole.

The polyolefin copolymer also contains polymerized units of an ethylenically unsaturated carboxylic acid or derivative thereof (e.g., an anhydride). It is believed that inclusion of such acidic groups may improve adhesion.

In some embodiments, the polyolefin copolymer has an acid number of less than 40, 35, 30, or 25 mgKOH/g. The acid value can be determined by titration with a base, and is defined as the value (in mg) of the base (e.g., potassium hydroxide) required to neutralize 1g of the polymer. When the concentration of the carboxylic acid and its unsaturated derivative is too high, the polyolefin copolymer may be immiscible with the polyisobutylene component due to phase separation, insufficient adhesion, and/or high haze.

Examples of ethylenically unsaturated carboxylic acids and their (e.g. unsaturated) derivatives (including anhydrides) include fumaric acid, maleic acid, itaconic acid, citraconic acid, aconitic acid, nadic acid (nadic acid) and their anhydrides, methyl fumarate, ethyl fumarate, propyl fumarate, butyl fumarate, dimethyl fumarate, diethyl fumarate, dipropyl fumarate, dibutyl fumarate, methyl maleate, ethyl maleate, propyl maleate, butyl maleate, dimethyl maleate, diethyl maleate, dipropyl maleate, dibutyl maleate, maleimide and N-phenyl maleimide, and preferably are itaconic anhydride and maleic anhydride. Combinations of one or more ethylenically unsaturated carboxylic acids and one or more (e.g. unsaturated) derivatives thereof may be employed.

The polyolefin copolymer is preferably chlorine-free, having a chlorine content of less than 1 wt%, 0.5 wt%, 0.1 wt%, 0.01 wt%, or 0.001 wt%. When the polyolefin copolymer has a sufficiently low chlorine content, the OCA does not yellow during use. As just described, the adhesive composition is also free of chlorine.

In some embodiments, the polyolefin copolymer optionally further comprises polymerized units of at least one (meth) acryloyl monomer. Examples include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, glycidyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, benzyl (meth) acrylate) Phenyl acrylate, N-dimethylaminoethyl (meth) acrylate, N-diethylaminoethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, acetoacetoxyethyl (meth) acrylate, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, N-isobutyl (meth) acrylamide, N-tert-butyl (meth) acrylamide, N-dimethyl (meth) acrylamide, N-dimethylaminopropyl (meth) acrylamide, N-methylenebis (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-diethylaminoethyl (meth) acrylate, N-hydroxyethyl (meth) acrylate, N-acetoacetoxyethyl (meth) acrylamide, N-tert-butyl (meth) acrylamide, N-dimethyl (meth) acrylamide, N-dimethylaminopropyl (meth) acrylamide, N-methylidene-bis, Hydroxyethyl (meth) acrylamide, (meth) acryloylmorpholine, vinyl n-butyl ether, 4-hydroxybutyl vinyl ether and dodecyl vinyl ether. Monomers containing acrylamide or amino groups also generally contribute to improved adhesion. (meth) acrylic acid long-chain alkyl (e.g. C)₆-C₂₀Or C₆-C₁₂) The ester may help to improve compatibility with the polyisobutylene in the adhesive.

In some embodiments, the polyolefin copolymer optionally comprises polymerized units of a (meth) acryloyl monomer. When present, the concentration of the (meth) acryloyl monomer is typically at least 0.01, 0.1, 0.5, or 1 weight percent of the polyolefin copolymer and no greater than 30 or 20 weight percent of the polyolefin copolymer. In some embodiments, the concentration of the (meth) acryloyl monomer is less than 1, 0.5, 0.1, or 0.01 weight percent of the polyolefin copolymer. The concentration of the (meth) acryloyl monomer may be determined by Fourier transform infrared spectroscopy or¹H-NMR.

The polyolefin copolymer may be prepared according to methods known in the art. (see, e.g., US8,519,046; which is incorporated herein by reference). In some embodiments, the polyolefin copolymer may be characterized as a propylene-based random copolymer comprising grafted carboxylic acid (e.g., maleic) anhydride and (meth) acryloyl monomers.

In some embodiments, the polyolefin copolymer has a melting temperature of 50 ℃ to 150 ℃ measured according to DSC at a rate of 10 ℃/minute. In some embodiments, the onset of melting temperature is at least 55 ℃ or 60 ℃. In some embodiments, the melting temperature is no greater than 100 ℃, 90 ℃, or 80 ℃.

Suitable polyolefin copolymer materials are commercially available from Nippon Paper Group (Nippon Paper Group) in Japan under the trade designations "AUROREN 350S" and "AUROREN 353S".

The adhesive composition may optionally include one or more additives such as tackifiers, plasticizers (e.g., oils, polymers that are liquid at 25 ℃), antioxidants (e.g., hindered phenol compounds, phosphate esters, or derivatives thereof), ultraviolet light absorbers (e.g., benzotriazole, oxazole acid amide, benzophenone, or derivatives thereof), processing stabilizers (in-process stabilizers), corrosion inhibitors, deactivators, processing aids, elastomeric polymers (e.g., block copolymers), scavenger fillers (scuvenger fillers), nanoscale fillers, clear fillers, desiccants, crosslinkers, pigments, and the like. These additives may be used alone, and may be used in combination of two or more thereof. The total concentration of such additives ranges from 0 wt% to 60 wt% of the total adhesive composition.

When it is desired that the adhesive composition be transparent, the adhesive is typically free of fillers having a particle size greater than 100nm, which may reduce the transparency of the adhesive composition. In this embodiment, the total amount of filler of the adhesive composition is no greater than 10, 9, 8, 7, 6, 5, 4, 3, or 2 wt.% solids of the adhesive composition. In some advantageous embodiments, the adhesive composition comprises no greater than 1 wt.%, 0.5 wt.%, 0.1 wt.%, or 0.05 wt.% filler.

However, in other embodiments, the adhesive composition may include higher amounts of inorganic oxide fillers (such as fumed silica).

In typical embodiments, the adhesive composition does not contain an acid-reactive component (such as an epoxy compound) that would cause crosslinking of the acid groups.

In typical embodiments, the adhesive composition does not contain styrene-isoprene-styrene (SIS) and/or styrene-butadiene-styrene (SBS) block copolymers.

The adhesives or OCA compositions disclosed herein may optionally comprise a tackifier. The addition of a tackifier gives the composition a higher adhesion, which is beneficial for some applications where adhesion to different substrates is a critical requirement. The addition of a tackifier increases the Tg of the composition and may reduce its storage modulus at room temperature, thereby making it less elastic and more fluid, such as is required to follow the ink steps during lamination. However, the same addition of tackifier may shift the viscoelastic balance too much to viscous behavior, such as in those cases where minimal creep and thus less flowability is required. Thus, the addition of a tackifier is optional and its presence and concentration depends on the particular application.

Suitable tackifiers include hydrocarbon resins and hydrogenated hydrocarbon resins, such as hydrogenated cycloaliphatic resins, hydrogenated aromatic resins, or combinations thereof. Suitable tackifiers are commercially available and include, for example, those available under the trade name ARKON (e.g., ARKON P or ARKON M) from waste Chemical Industries co., Osaka, Japan (Osaka, Japan); those available under the trade name ESCOREZ (e.g., ESCOREZ 1315, 1310LC, 1304, 5300, 5320, 5340, 5380, 5400, 5415, 5600, 5615, 5637, and 5690) from Exxon Mobil Corporation, Houston, TX; and those available from Eastman Chemical company (Eastman Chemical, Kingsport, TN) of kingbaud, tennessee under the trade names REGALREZ (e.g., REGALREZ 1085, 1094, 1126, 1139, 3102, and 6108). These tackifiers are particularly advantageous for OCA-type applications due to their low color and environmental stability.

The tackifier may have any suitable softening temperature or softening point. The softening temperature is generally less than 200 ℃, less than 180 ℃, less than 160 ℃, less than 150 ℃, less than 125 ℃ or less than 120 ℃. However, in applications where heat tends to be generated or where the adhesive bond is exposed to heat, tackifiers having softening points of at least 75 ℃ are typically selected. Such softening points help minimize separation of the tackifier from the remainder of the adhesive composition when the adhesive composition is subjected to heat, such as from an electronic device or component. The softening temperature is generally selected to be at least 80 ℃, at least 85 ℃, at least 90 ℃ or at least 95 ℃. However, in applications where heat is not generated or where the adhesive bond is not exposed to heat, the tackifier may have a softening point of less than 75 ℃.

In some embodiments, the adhesive composition comprises a tackifier. The concentration of tackifier may vary depending on the intended (e.g., pressure sensitive) adhesive composition. In some embodiments, the amount of tackifier is at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 weight%. The maximum amount of tackifier is typically no greater than 60, 55, 50, 45, 40, 35, or 30 weight percent. Increasing (e.g., solid at 25 ℃) tackifier concentration generally increases the Tg of the adhesive. In other embodiments, the adhesive composition contains little or no tackifier. Thus, the concentration of tackifier is less than 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, 0.5 wt%, or 0.1 wt%.

In addition, liquid rheology modifiers such as plasticizers or oils may also be used, for example, mineral oil (Kaydol), naphthenic oil (Calsol 5550), and paraffinic oil (Hyprene P100N) may be used in combination with tackifiers, the benefit of using a plasticizer/oil in combination with an adhesion promoter is that it allows the glass transition temperature of the composition to be reduced in addition to reducing the storage modulus of the composition⁴A creep compliance of 1/Pa is most desirable for optimal lamination coverage over commercial ink step features.

The adhesive or OCA composition disclosed herein may further comprise a UV blocker. The UV-blocking package includes a UV absorber or a combination of a UV absorber and a light stabilizer. Examples of suitable UV absorbers include, but are not limited to, benzophenones, benzotriazoles, triazines, or combinations thereof. Examples of light stabilizers include, but are not limited to, Hindered Amine Light Stabilizers (HALS). The adhesive sheet of the present invention has neutral color and low haze, which are necessary for an optically clear adhesive. The adhesive sheet of the present invention has a clear UV cut-off, examples of which include, but are not limited to, less than 1.5% transmission (T) at 380nm wavelength, less than 84% T at 400nm wavelength, and greater than 96% T at 410nm wavelength and above, which can effectively block UV light or even violet or blue light, but does not cause excessive yellow.

In some embodiments, the adhesive composition is prepared by dissolving the polyisobutylene polymer and other optional components in an organic solvent. Suitable solvents include, for example, alkanes, ethyl acetate, toluene and tetrahydrofuran. In other embodiments, the adhesive composition may be characterized as a hot melt adhesive. Such adhesive compositions are typically applied from a melt and are solvent free. Alternatively, a cured hot melt or a dried solvent-based adhesive may be applied to or between the substrates. As will be described later, the adhesive may be heated after it is applied to the substrate.

The adhesive layer typically has a thickness of at least 10 micrometers, 15 micrometers, 20 micrometers, or 25 micrometers (1 mil) and a thickness ranging up to 500 micrometers (20 mils). In some embodiments, the adhesive layer has a thickness of no greater than 400 microns, 300 microns, 200 microns, or 100 microns. The adhesive composition can be applied as a single layer or as multiple layers. The layers may be continuous or discontinuous.

The adhesive composition can be coated on a variety of flexible and non-flexible backing materials using conventional coating techniques to produce single or double coated adhesive tapes and adhesive transfer tapes. Generally, an adhesive transfer tape includes an adhesive layer disposed on a release liner. Such products can be formed by applying (e.g., coating, casting, or extruding) the adhesive onto a release liner, and drying the adhesive (if an organic solvent is present).

The tape may also include a release material or release liner. For example, in the case of single-coated tapes, the side of the backing surface opposite where the adhesive is disposed is typically coated with a suitable release material. Release materials are known and include materials such as, for example, silicone, polyethylene, polyurethane, polyacrylic, and the like. For double coated tapes, a second layer of adhesive is disposed on the opposite surface of the backing surface. The second layer may also comprise an adhesive composition as described herein or a different adhesive composition.

A flexible substrate is defined herein as any material that is conventionally used as a tape backing or that may have any other flexible material. Examples include, but are not limited to, polymeric films, woven or nonwoven fabrics (e.g., scrims); metal foils, foams (e.g., polyacrylics, polyethylene, polyurethane, neoprene), and combinations thereof (e.g., metallized polymer films). Polymeric films include, for example, polypropylene (e.g., biaxially oriented), polyethylene (e.g., high or low density), polyvinyl chloride, polyurethane, polyester (polyethylene terephthalate), polycarbonate, poly (methyl (meth) acrylate) (PMMA), polyvinyl butyral, polyimide, polyamide, fluoropolymer, cellulose acetate, cellulose triacetate, and ethyl cellulose, and the like. Woven or nonwoven fabrics may comprise fibers or filaments of synthetic or natural materials such as cellulose (e.g., tissue), cotton, nylon, rayon, glass, ceramic materials, and the like.

Substrates may be bonded by the adhesive compositions described herein or by (e.g., transfer) single or double coated tapes. The substrate may comprise the same materials as those just described for the backing.

One method of bonding includes providing a first substrate and contacting a surface of the first substrate with a (e.g., pressure sensitive) adhesive. In this embodiment, the opposing surface of the adhesive is typically temporarily covered by a release liner.

In other embodiments, the method further comprises contacting an opposing surface of the (e.g., pressure sensitive) adhesive (e.g., layer) with a second substrate. The first and second substrates may be composed of various materials as previously described, such as metals, inorganic materials (e.g., glass), organic polymer materials, or combinations thereof.

In some bonding methods, the substrate, the (e.g., pressure sensitive) adhesive composition, or a combination thereof, may be heated to reduce the storage modulus (G'), and thereby increase the development of bond strength. The substrate and/or (e.g. pressure sensitive) adhesive may be heated to a temperature of up to 30 ℃, or 35 ℃, or 40 ℃, or 45 ℃, or 50 ℃, or 55 ℃, or 60 ℃, or 65 ℃, or 70 ℃. In some embodiments, one or more substrates are heated in an oven to a desired temperature with an adhesive bonded to the one or more substrates by an initial peel adhesion strength at ambient temperature (e.g., 25 ℃). In other embodiments, the substrate and/or (e.g., pressure sensitive) adhesive are heated by a heat gun.

In some embodiments, the (e.g. pressure sensitive) adhesive compositions described herein are optically clear. Thus, certain articles can be laminates that include an optically transparent substrate (e.g., an optical substrate such as an optical film) and an optically transparent adhesive layer disposed on at least one major surface of the optically transparent substrate. The laminate may further include a second substrate permanently or temporarily attached to the pressure sensitive adhesive layer, and wherein the pressure sensitive adhesive layer is positioned between the optically transparent substrate and the second substrate.

In one embodiment, the laminate may be a removable or permanent surface protective film. In some embodiments, the tape and protective film may be used in (e.g., illuminated) displays that may be incorporated into household appliances, automobiles, computers (e.g., tablets), and various handheld devices (e.g., phones). In other embodiments, the adhesive-coated film may be suitable for use in architectural applications, glazing (e.g., windows and windshields), and graphic film applications.

In some embodiments, the (e.g. pressure sensitive) adhesive and optically transparent substrate (e.g. transparent film) have a transmission of at least 90% for an adhesive layer having a thickness of 50 microns measured according to the test method described in the examples for visible light (410 nm). In some embodiments, the transmittance is at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%.

In some exemplary laminates (where an optically clear pressure sensitive adhesive layer is positioned between two substrates), at least one of the substrates is an optical film, a display unit (e.g., a Liquid Crystal Display (LCD), an Organic Light Emitting Display (OLED), a touch sensor, or a lens Esters, cyclic olefin copolymers, light-transmitting polyimides, polycarbonates, or polymethyl methacrylates), crack resistance films, and electromagnetic interference filters. Some of these films may also be used as ITO (i.e., indium tin oxide) coatings or patterned substrates, such as those used to make touch sensors. The low water absorption and WVTR of the adhesives described herein provide a stable, low dielectric constant OCA that can be very advantageously used in touch sensor applications to both protect the sensor and integrated conductors from environmental and corrosive effects, and also minimize electronic noise communication with the sensor. In some embodiments, the (e.g., pressure sensitive) adhesives and (e.g., transfer and double-coated) tapes described herein are useful for bonding interior or exterior components of optical elements, such as illuminated display devices, such as liquid crystal displays ("LCDs") and light emitting diode ("LED") displays (such as battery cell phones (including smart phones), wearable (e.g., wrist) devices, automotive navigation systems, global positioning systems, depth detectors, computer monitors, notebook computers, and tablet computer displays). Other types of optical elements include projection (e.g., lens) components, photonic components, and polarizing beamsplitters.

In some embodiments, (e.g. pressure sensitive) adhesives are suitable for use as encapsulating compositions for use in electronic devices as described, for example, in US 2009/0026924; this patent is incorporated herein by reference.

In particular, the (e.g., pressure-sensitive) adhesive can be used as a sealing member for electronic devices such as organic transistors, organic memories, and organic EL elements; a liquid crystal display; an electronic paper sheet; a thin film transistor; an electrochromic device; an electrochemical light emitting device; a touch panel; a solar cell; a thermoelectric conversion device; a piezoelectric conversion device; an electrical storage device; and so on.

In addition to various optically-related applications and/or electronic display assembly applications, the adhesive compositions described herein can be used in a variety of other articles. The following non-limiting examples further describe exemplary adhesives and adhesive articles of the present disclosure, and exemplary methods for making such adhesives and adhesive articles. All percentages are by weight unless otherwise indicated.