Anti-floating acrylic rubber foam and double-sided tape comprising same

Abstract

The invention relates to a core material in a double-sided tape for adhering components of an electronic mobile device and a double-sided tape comprising said core material. Specifically, the invention discloses a self-adhesive acrylic rubber foam which comprises the following components in parts by weight: a) 80-120 parts of acrylic resin; b) 10-50 parts by weight of a block copolymer; c) 10 to 30 parts by weight of terpene phenol resin; and d) 0.5-10 parts by weight of a filler. The acrylic rubber foam has significantly improved micro-shear and impact resistance, and effectively avoids the floating phenomenon of a double-sided tape in an electronic mobile device assembly in the use process.

Description

Technical Field

[0001] This invention relates to the field of adhesive tapes, and more specifically to an anti-buoyancy acrylic rubber foam and a double-sided adhesive tape that exhibits excellent anti-buoyancy and impact resistance by including an acrylic rubber foam as a core layer. Background Technology

[0002] The assembly of electronic mobile devices often involves the adhesion between components. For example, the screen and back cover of an electronic mobile device typically require the use of suitable double-sided tape for adhesion. After undergoing harsh high-temperature and high-humidity environmental testing, the tape is prone to deformation under stress in the Z-direction, causing the back cover of the mobile device to lift up. Figure 1 This is not an adhesive failure, but rather a result of insufficient cohesive strength of the foam material used as the core layer in the double-sided tape. This places higher demands on the material development for the foam layer of double-sided tape.

[0003] Therefore, there is an urgent need in this field to develop new rubber foams with anti-buoyancy and impact resistance that can be used as the core layer of double-sided adhesive tape. Summary of the Invention

[0004] The purpose of this invention is to provide a rubber foam with anti-buoyancy and anti-impact properties, and a double-sided tape containing the same.

[0005] A first aspect of the present invention provides a self-adhesive acrylic rubber foam, said acrylic rubber foam comprising:

[0006] (a) 80-120 parts by weight of acrylic resin;

[0007] (b) 10-50 parts by weight of block copolymer;

[0008] (c) 10-30 parts by weight of terpene phenol resin; and

[0009] (d) 0.5-10 parts by weight of filler.

[0010] In another preferred embodiment, the acrylic resin comprises: repeating unit A derived from a first monomer and repeating unit B derived from a second monomer.

[0011] In another preferred embodiment, the first monomer is selected from alkyl acrylate monomers.

[0012] In another preferred embodiment, the alkyl acrylate monomer is selected from n-butyl acrylate (BA), 2-ethylhexyl acrylate (2-EHA), isooctyl acrylate (IOA), hydroxyethyl acrylate (2-HEA), 4-hydroxybutyl acrylate (4-HBA), and 2-hydroxypropyl acrylate (HPA).

[0013] In another preferred embodiment, the second monomer is selected from an olefinic unsaturated comonomer containing a carboxyl group.

[0014] In another preferred embodiment, the carboxyl-containing olefinic unsaturated comonomer is selected from acrylic acid (AA) or methacrylic acid.

[0015] In another preferred embodiment, the content of repeating unit A derived from the first monomer is 70-98 wt%, more preferably 85-95 wt%, and even more preferably 85-90%, based on the total weight of the acrylic resin.

[0016] In another preferred embodiment, the content of repeating unit B derived from the second monomer is 1-30 wt%, more preferably 5-15 wt%, and more preferably 8-15%, based on the total weight of the acrylic resin.

[0017] In another preferred embodiment, the acrylic resin comprises: 70-99 by weight of repeating unit A derived from a first monomer and 1-30 by weight of repeating unit B derived from a second monomer, based on the total weight of the acrylic resin.

[0018] In another preferred embodiment, the acrylic resin comprises: 75-95 by weight of repeating unit A derived from a first monomer and 5-15 by weight of repeating unit B derived from a second monomer, based on the total weight of the acrylic resin.

[0019] In another preferred embodiment, the block copolymer is selected from the group consisting of: SBS (styrene-butadiene-styrene) block copolymer, SIS (styrene-isoprene-styrene) block copolymer, SB (styrene-butadiene) block copolymer, SBBS (styrene-butadiene / butene-styrene) block copolymer, SEBS (styrene-ethylene / butene-styrene) block copolymer, SEPS (styrene-ethylene / propylene-styrene) block copolymer, and SEP (styrene-ethylene / propylene) block copolymer. Preferably, the block copolymer includes SBS block copolymer, SB block copolymer, and SEBS block copolymer.

[0020] In another preferred embodiment, the block copolymer is an SBS block copolymer.

[0021] In another preferred embodiment, the content of the block copolymer is 10-45 parts by weight, more preferably 12-45 parts by weight.

[0022] In another preferred embodiment, the softening temperature (ring and ball method) of the terpene phenol resin is 100-130°C; more preferably, 105-120°C.

[0023] In another preferred embodiment, the content of the terpene phenol resin is 10-25 parts by weight, more preferably 12-25 parts by weight.

[0024] In another preferred embodiment, the glass transition temperature of the terpene phenol resin is 50-80°C; more preferably, 55-75°C.

[0025] In another preferred embodiment, the hydroxyl value of the terpene phenol resin is 20-70 mg KOH / g, more preferably 20-60 mg KOH / g.

[0026] In another preferred embodiment, the filler comprises: hollow glass microspheres (HGS), hollow organic microspheres, or a combination thereof.

[0027] In another preferred embodiment, the filler comprises expanded organic microspheres.

[0028] In another preferred embodiment, the filler content is 0.5-15 parts by weight, more preferably 1-10 parts by weight, and even more preferably 1-5 parts by weight.

[0029] In another preferred embodiment, the filler comprises hollow glass microspheres in a content of 3-8 parts by weight, preferably 4-6 parts by weight.

[0030] In another preferred embodiment, the filler comprises expanded organic microspheres in a content of 0.5-5 parts by weight, preferably 1-3 parts by weight.

[0031] In another preferred embodiment, the hollow glass microspheres have a particle size of 65 micrometers.

[0032] In another preferred embodiment, the expanded organic microspheres (MB) have a particle size of 20-40 micrometers (after expansion).

[0033] In another preferred embodiment, the acrylic rubber foam further includes additional additives selected from the group consisting of pigments, aging inhibitors, antioxidants, light stabilizers, UV protectants, flame retardants, or combinations thereof.

[0034] In another preferred embodiment, the additive content is 0.1-5 parts by weight, more preferably 0.1-1 parts by weight, and even more preferably 0.1-0.5 parts by weight.

[0035] In another preferred embodiment, the acrylic rubber foam is obtained by UV polymerization of the first monomer and the second monomer in the presence of at least one crosslinking agent and a photoinitiator.

[0036] In another preferred embodiment, the crosslinking agent is selected from one or more of diacrylates and triacrylates. Specific examples of such diacrylates include 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate (HDDA), 1,9-nonanediol acrylate, and tripropylene glycol diacrylate.

[0037] In another preferred embodiment, the crosslinking agent content is 0.1-1 parts by weight, more preferably 0.1-0.5 parts by weight.

[0038] In another preferred embodiment, the photoinitiator is selected from the group consisting of 1-hydroxycyclohexylphenyl ketone (Irgacure 184), 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651), 2-hydroxy-methylphenylpropane-1-one (1173), or 2,4,6-trimethylbenzoylphosphine dioxide. This photopolymerization initiator can be used alone or in combination.

[0039] In another preferred embodiment, the photoinitiator content is 0.4-2 parts by weight, more preferably 0.5-1.5 parts by weight.

[0040] In another preferred embodiment, the micro shear of the acrylic rubber foam is 20 to 200 μm, as determined by a micro shear test method.

[0041] In another preferred embodiment, the micro shear of the acrylic rubber foam is 30 to 200 μm, preferably 30-120 μm, more preferably 30-100 μm, even more preferably 30-80 μm, and most preferably 30-60 μm, as determined by a micro shear test method.

[0042] In another preferred embodiment, the acrylic rubber foam has an impact resistance of 980 to 2000 mJ, as determined by the DuPont-Z test method.

[0043] In another preferred embodiment, the impact resistance of the acrylic rubber foam is 980 to 1500 mJ, preferably 1000 to 1500 mJ, more preferably 1020 to 1500 mJ, even more preferably 1050 to 1500 mJ, and most preferably 1100 to 1500 mJ, as determined according to the DuPont-Z test method.

[0044] In another preferred embodiment, the 180° peel strength (180°PA) of the acrylic rubber foam is 5 to 15 N / cm, as determined according to the 180° peel strength test method (180°PA test).

[0045] In another preferred embodiment, the 180° peel strength (180°PA) of the acrylic rubber foam is 5 to 13 N / cm, more preferably 5.5 to 13 N / cm, more preferably 6 to 13 N / cm, and even more preferably 8 to 13 N / cm, as determined according to the 180° peel strength test method (180°PA test).

[0046] In another preferred embodiment, the density of the acrylic rubber foam is 600-1000 kg / m³. 3 The optimal temperature is 700-900 kg / m³. 3 Better 800-860kg / m 3 .

[0047] In another preferred embodiment, the acrylic rubber foam comprises:

[0048] acrylic resins 80-120 parts by weight Block copolymers 10-50 parts by weight Terpene phenol resin 10-50 parts by weight filler 1-10 parts by weight.

[0049] In another preferred embodiment, the acrylic rubber foam comprises:

[0050] acrylic resins 90-110 parts by weight SBS 10-30 parts by weight Terpene phenol resin 10-50 parts by weight filler 1-10 parts by weight.

[0051] In another preferred embodiment, the acrylic rubber foam comprises:

[0052] acrylic resins 100 parts by weight SBS 10-30 parts by weight T105 10-30 parts by weight filler 1-5 parts by weight.

[0053] A second aspect of the present invention provides a double-sided adhesive tape, the double-sided adhesive tape comprising:

[0054] 1) A rubber foam layer composed of acrylic rubber foam as described in the first aspect of the present invention; and

[0055] 2) Two adhesive layers located on both sides of the rubber foam layer.

[0056] In another preferred embodiment, the rubber foam layer has a thickness of 50-300 μm; more preferably, a thickness of 50-250 μm; and even more preferably, a thickness of 100-250 μm.

[0057] In another preferred embodiment, each of the adhesive layers has an independent thickness of 5-150 μm; more preferably, 10-100 μm; and even more preferably, 20-80 μm.

[0058] In another preferred embodiment, the adhesive is selected from conventional pressure-sensitive adhesives (PSA), such as solvent-based acrylic adhesives or UV-curable acrylic adhesives.

[0059] A third aspect of the invention provides the use of acrylic rubber foam as described in the first aspect of the invention, for use as the core layer of double-sided tape or for bonding two substrates.

[0060] In another preferred embodiment, the double-sided tape is used to bond two substrates together.

[0061] In another preferred embodiment, the two substrates are components of a mobile device.

[0062] A fourth aspect of the invention provides an assembly in which two substrates are bonded together by double-sided adhesive tape as described in the second aspect of the invention, wherein the two substrates are preferably components of a mobile device.

[0063] In another preferred embodiment, the substrate is selected from the group consisting of glass substrates, plastic substrates, and metal substrates.

[0064] It should be understood that, within the scope of this invention, the above-described technical features of this invention and the technical features specifically described below (such as in the embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be described in detail here. Attached Figure Description

[0065] Figure 1 This diagram illustrates the application scenarios of acrylic rubber foam in mobile electronic devices. In Figure A, the red area (indicated by the arrow) represents the location of the double-sided tape containing acrylic rubber foam; Figure B shows the phenomenon of the foam layer in the double-sided tape floating up at the back cover of the mobile device.

[0066] Figure 2 This diagram illustrates the experimental method for the 180° peel force test.

[0067] Figure 3 This diagram illustrates the experimental method for the micro-shear test.

[0068] Figure 4 This diagram illustrates the experimental method of the DuPont impact test.

[0069] Figure 5 A schematic diagram showing a double-sided adhesive tape with an acrylic rubber foam core layer as described in this invention;

[0070] In the diagram, the labels are as follows: 1-core layer; 2-first adhesive layer; 3-second adhesive layer. Detailed Implementation

[0071] Through extensive and in-depth research, the inventors have developed for the first time a rubber foam material with excellent anti-buoyancy and impact resistance. Specifically, the inventors unexpectedly discovered that by simultaneously adding terpene phenolic resin and block copolymer components during the preparation of acrylic rubber foam, the resulting rubber foam, when used as the core layer of double-sided tape, exhibits significantly improved anti-buoyancy and impact resistance, making it highly suitable for use in double-sided tapes for bonding electronic mobile device components.

[0072] the term

[0073] As used herein, the terms “containing” or “including (comprise)” can be open-ended, semi-closed, or closed. In other words, the terms also include “consistently made of” or “composed of”.

[0074] As used herein, the terms "acrylic rubber foam," "rubber foam of the present invention," and "rubber foam layer of the present invention" are used interchangeably to refer to the acrylic rubber foam described in the first aspect of the present invention.

[0075] As used herein, the terms "repeating unit derived from the first monomer" and "repeating unit derived from the second monomer" respectively refer to the repeating units comprising the polymer backbone of the acrylic resin of the present invention, which include repeating units derived from the first monomer and repeating units derived from the second monomer.

[0076] The self-adhesive acrylic rubber foam of the present invention

[0077] As used herein, the terms "acrylic rubber foam of the present invention", "rubber foam of the present invention", "pressure-sensitive adhesive rubber foam of the present invention", and "self-adhesive acrylic rubber foam of the present invention" are used interchangeably to refer to the acrylic rubber foam described in the first aspect of the present invention.

[0078] The acrylic rubber foam of the present invention contains a specific ratio of acrylic resin, block copolymer, terpene phenol resin and filler, and has excellent self-adhesion and significantly improved anti-buoyancy and impact resistance, thereby exhibiting excellent overall performance.

[0079] Typically, the acrylic rubber foam of the present invention is obtained by UV polymerization in the presence of a crosslinking agent and a photoinitiator, wherein the acrylic rubber foam comprises:

[0080] (a) 80-120 parts by weight of acrylic resin;

[0081] (b) 10-50 parts by weight of block copolymer;

[0082] (c) 10-30 parts by weight of terpene phenol resin; and

[0083] (d) 0.5-10 parts by weight of filler.

[0084] Acrylic resins (component a)

[0085] The acrylic resins described in this invention are the main components of acrylic rubber foams. The acrylic resins of this invention can be obtained by photoinitiated polymerization of one, two, or more acrylic monomers. For example, monomers that can be used to prepare the acrylic resins of this invention include alkyl acrylates, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and isooctyl (meth)acrylate. Esters, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecanyl (meth)acrylate, octadecyl (meth)acrylate, nonadecanyl (meth)acrylate, eicosyl (meth)acrylate, isooctadecyl (meth)acrylate, or combinations thereof.

[0086] Monomers that can be used to prepare the acrylic resins of the present invention also include monomers with polar functional groups, such as acrylate monomers containing hydroxyl or carboxyl groups. Examples include acrylic acid, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, or combinations thereof.

[0087] Block copolymer (component b)

[0088] The introduction of block copolymers increases the overall elasticity of the polymer and improves its creep resistance, thereby enhancing the impact resistance and buoyancy resistance of acrylic rubber foams. The block copolymers described in this invention contain two or more polymer segments in their main chain. Block copolymers that can be used in this invention include, but are not limited to, styrene-butadiene-styrene block copolymers (SBS), SIS (styrene-isoprene-styrene) block copolymers, SB (styrene-butadiene) block copolymers, SBBS (styrene-butadiene / butene-styrene) block copolymers, SEBS (styrene-ethylene / butene-styrene) block copolymers, SEPS (styrene-ethylene / propylene-styrene) block copolymers, and SEP (styrene-ethylene / propylene) block copolymers. Preferred block copolymers include SBS, SB, and SEBS.

[0089] Terpene phenol resin (component c)

[0090] The terpene phenol resin described in this invention is a terpene phenol resin containing unsaturated bonds. The terpene phenol resin used in this invention has a low molecular weight and good compatibility with acrylic resins and block copolymers. Typically, the molecular weight of the terpene phenol resin is ≤800, preferably ≤600, and more preferably 500. The softening temperature (ring and ball method) of the terpene phenol resin used in this invention is 100-130°C; preferably, 105-120°C.

[0091] The glass transition temperature of the terpene phenol resin of the present invention is 50-80°C; preferably, 55-75°C.

[0092] The terpene phenol resin of the present invention has a hydroxyl value of 20-70 mg KOH / g, preferably 20-60 mg KOH / g. The terpene phenol resin includes, but is not limited to, T105, T115, and H150. For example, the T105 and T115 terpene phenol resins used in the present invention have a softening temperature of 105 to 120°C, a glass transition temperature of 55-70°C, a hydroxyl value of 20-60, and an average molecular weight of about 500.

[0093] Packing material (component d)

[0094] The filler described in this invention is used to form micropores within acrylic rubber foam. As a filler, fillers containing gas and comprising a shell made of inorganic or organic materials can be used. For example, glass bubbles, organic microspheres, or mixtures thereof can be used as fillers, but other fillers may also be used as needed.

[0095] Additives (component e)

[0096] The acrylic rubber foam of the present invention may also contain one or more different additives, including but not limited to surfactants, plasticizers (different from physical foaming agents), nucleating agents (e.g., talc, silica, or TiO2), fillers (e.g., inorganic and organic fillers), fibers, aging inhibitors, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, pigments, dyes, reinforcing agents, hydrophobic or hydrophilic silica, calcium carbonate, toughening agents, flame retardants, fine powdered polymer particles (e.g., polyester, nylon, or polypropylene), stabilizers (e.g., UV stabilizers), and combinations thereof.

[0097] Crosslinking agent and photoinitiator (components f and g)

[0098] The crosslinking agent (component f) of the present invention may be selected from one or more of diacrylates and triacrylates. Specific examples of such diacrylates include 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate (HDDA), 1,9-nonanediol acrylate, and tripropylene glycol diacrylate.

[0099] The photoinitiator (component g) of the present invention may be selected from 1-hydroxycyclohexylphenyl ketone (Irgacure 184), 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651), 2-hydroxymethylphenylpropane-1-one (1173), or 2,4,6-trimethylbenzoylphosphine dioxide. This photopolymerization initiator may be used alone or in combination. The total content of the photoinitiator used in the present invention is 0.4-2 parts by weight, preferably 0.5-1.5 parts by weight.

[0100] Currently, the core material of common double-sided tapes is produced using an extrusion process, resulting in a limited polymer molecular weight. This makes the tape more prone to deformation under high temperatures and external forces. For example, stress in the Z-direction can cause the tape to float. In contrast, polymers produced using UV curing technology have a larger molecular weight, and the introduction of block copolymers increases the overall elasticity of the polymer, improving its creep resistance.

[0101] Double-sided tape

[0102] The double-sided tape of this invention uses acrylic rubber foam as the core layer, with adhesive layers disposed on both sides of the core layer. The adhesive layer is a pressure-sensitive adhesive; the material of the pressure-sensitive adhesive is not limited, as long as it possesses excellent adhesive properties, such as acrylic pressure-sensitive adhesives, rubber pressure-sensitive adhesives, polyurethane pressure-sensitive adhesives, silicone pressure-sensitive adhesives, etc. For example, a representative schematic diagram of the double-sided tape is shown below. Figure 5As shown. Preferably, the acrylic rubber foam in the double-sided tape of the present invention has a thickness of 50-300 μm; more preferably, 50-250 μm; more preferably, 100-250 μm. Each adhesive layer in the double-sided tape of the present invention independently has a thickness of 5-150 μm; more preferably, 10-100 μm; more preferably, 20-80 μm. The double-sided tape of the present invention may optionally also include structural layers such as a release liner, an additional adhesive layer, a primer layer, a filament layer, and a printing layer.

[0103] The term "mobile device" includes, for example, equipment in the consumer electronics industry, including electronic, optical, and precision equipment, and in the context of this application, particularly those classified in Class 9 of the International Classification of Goods and Services for the Registration of Marks (Nice Classification); Class 10 (NCL(10-2013)), provided that these are electronic, optical, or precision equipment; and clocks and timekeeping devices in Class 14 (NCL(10-2013)), particularly scientific, nautical, surveying, photographic, film, optical, weighing, measuring, signaling, monitoring, rescue, and indicating equipment and instruments; equipment and instruments for conducting, switching, converting, storing, regulating, and monitoring electricity; and equipment for recording, processing, transmitting, and reproducing images. Examples of equipment include: television sets; sound recording, processing, transmission, and reproduction equipment, such as broadcasting equipment; computers, computing instruments and data processing equipment, mathematical equipment and instruments, computer accessories, office equipment—such as printers, fax machines, copiers, and typewriters—data storage devices; telecommunications equipment and multifunctional equipment with telecommunications functions, such as telephones and answering machines; chemical and physical measuring equipment, control equipment and instruments, such as battery chargers, multimeters, lamps, and tachometers; nautical equipment and instruments; optical equipment and instruments; medical equipment and instruments, as well as equipment for athletes; clocks and timers; solar cell modules, such as electrochemical dye solar cells, organic solar cells, and thin-film batteries; and fire extinguishing equipment.

[0104] Test methods

[0105] 180° Peel Strength Test (180° PA test)

[0106] The 180° peel force is used to evaluate the adhesive performance of a product. A schematic diagram of the 180° peel force test is shown below. Figure 2As shown. Specifically, adhesive tape (approximately 150 mm in length and 25 mm in width) cut from each sample specimen was adhered to a 36 μm PET reinforcing film, and then the test surface was bonded to a steel test plate cleaned with acetone. The adhesive tape was rolled twice back and forth with a rubber-coated 2 kg steel rod at a speed of 10 m / s, and aged for 20 minutes at 23 ± 1 °C and 50 ± 5% humidity. The peel force at 180 degrees (at ambient temperature, tensile rate of 300 mm / min) was then measured using a tensile testing machine (unit: N / cm). The acceptable peel force for actual use of the adhesive tape should be >5 N / cm.

[0107] High-performance anti-buoyancy test – Micro shear test

[0108] The anti-buoyancy performance of a product is evaluated through a micro-shear test. This test is used to accelerate the testing of the shear strength of the adhesive tape under temperature load. A schematic diagram of the micro-shear test is shown below. Figure 3 As shown.

[0109] Sample preparation for microshear testing:

[0110] Adhesive tape (approximately 50 mm in length and 10 mm in width) cut from each sample specimen is adhered to a steel test plate cleaned with acetone, such that the steel plate protrudes to the left and right beyond the adhesive tape, and the adhesive tape hangs 2 mm above the top of the test plate.

[0111] The bonding area of ​​the sample was 13mm x 10mm (height x width). It was then rolled six times on the bonding surface using a 2kg steel rod at a speed of 10m / min. The adhesive tape was reinforced by being flush with a stable adhesive strip, which served as a support for the travel sensor. The sample was then suspended vertically via a test plate.

[0112] The sample was loaded with a weight of 500g at the bottom. The test temperature was 40℃, and the test time was 30 minutes (15 minutes loading, 15 minutes unloading). The recorded shear stroke (in μm) after the specified test duration at a constant temperature is the maximum value. The smaller the value, the stronger the cohesion of the adhesive tape and the better its anti-buoyancy performance. When the shear stroke of the adhesive tape is <100μm, it has excellent anti-buoyancy performance in practical use. When the shear stroke of the adhesive tape is 100-200μm, the anti-buoyancy performance is good. When the shear stroke of the adhesive tape is >200μm, the anti-buoyancy performance is poor.

[0113] DuPont impact test (DuPont-Z test)

[0114] The DuPont impact test is used to evaluate the impact strength and toughness of a product. A schematic diagram of the DuPont impact test is shown below. Figure 4As shown. Specifically, under an environment of 23±1℃ and 50±5% humidity, the pressure-sensitive adhesive composition was laser-cut into a U-shaped sample with an inner side length of 29mm×29mm and an outer side length of 33mm×33mm. A 45mm×45mm PC frame and a 35mm×35mm lens were wiped with alcohol and left to stand for 2 hours. The U-shaped adhesive sheet to be tested was then attached between the frame and the lens, a pressure of 248N was applied, and held for 5 seconds. After standing for 24 hours, an impact test was performed using a 150g impact head; separation of the lens and frame indicated failure. The 150g impact head was dropped from a height of 5cm to impact the sample. If the sample did not fail, the height was increased by another 5cm (10cm) for a free-fall impact; if the sample still did not fail, the height was increased by another 5cm (15cm), and so on. The height at which the sample failed was recorded. The DuPont impact resistance W was calculated as W = mgh (m is 150g, g is the acceleration due to gravity 9.8m / s²). 2 (where h is the final failure height of the sample). (Unit: J). In practical use, adhesive tapes with excellent impact resistance must meet the following requirement: W > 1000 mJ.

[0115] Compared with the prior art, the present invention has the following main advantages:

[0116] (1) The acrylic rubber foam of the present invention has excellent anti-buoyancy properties.

[0117] (2) The acrylic rubber foam of the present invention has excellent impact resistance.

[0118] (3) The acrylic rubber foam of the present invention has excellent self-adhesive properties.

[0119] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise stated, percentages and parts are by weight.

[0120] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as are familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0121] Examples and Comparative Examples

[0122] The preparation process of the acrylic rubber foam layer of the present invention is as follows: First, the rubber and tackifying resin are weighed and pre-dissolved in acrylic monomers (2-EHA and AA mixed in a weight ratio of 88:12). The mixture is stirred for four hours using a disc mixer to prepare a semi-transparent mixture. Then, other photoinitiators, crosslinking agents, pigments and fillers are added according to the components and dosages shown in Table 2, and stirring is continued until a homogeneous mixture is obtained.

[0123] The prepared mixture was coated between two fluorosiloxane-treated polyethylene terephthalate carrier films using a two-roller coating speed of 20 cm / min, and then subjected to ultraviolet radiation (wavelength 365 nm, power 10 mw / cm). 2 Up to 25mw / cm 2 The mixture was processed for 5 minutes and then cured. Subsequently, the carrier film was removed to prepare a 200 μm thick acrylic rubber foam sheet. The resulting acrylic rubber foam sheet was used for peel strength and anti-buoyancy performance tests.

[0124] The carrier films on both sides of an acrylic rubber foam sheet are peeled off, and an acrylic adhesive layer (the pressure-sensitive adhesive layer of tesa 6618x) is laminated to both sides of the acrylic rubber to obtain a double-sided tape. The resulting double-sided tape is then used in a DuPont impact test.

[0125] The raw materials used in the acrylic rubber foam of the present invention are shown in Table 1.

[0126] Table 1

[0127]

[0128]

[0129] Using the formulation components in Table 2, corresponding acrylic rubber foams were prepared according to the aforementioned preparation methods.

[0130] Table 2

[0131]

[0132]

[0133]

[0134]

[0135] The peel strength, buoyancy resistance, and impact resistance of the acrylic rubber foams prepared using the formulations in Table 2 were measured using the aforementioned standard test methods. The results are shown in Table 3.

[0136] Table 3

[0137]

[0138]

[0139] Based on the application requirements of the product, an ideal acrylic rubber foam should have a 180° PA of ≥5.0 N / cm, a micro-shear of ≤200 μm, and an impact resistance of ≥1000 mJ (DuPont-Z).

[0140] Comparing Comparative Examples 1-7 reveals that, without the addition of the block copolymer (component b), the adhesive tape exhibits poor anti-buoyancy and impact resistance. Even with Comparative Example 1—using P240 type tackifying resin to achieve the best relative performance after screening different types of tackifying resins and adjusting the proportions of each component, relatively good anti-buoyancy (155 μm) was obtained, but the impact resistance still failed to meet practical requirements (700 mJ). Comparative Example 2, using T105 type tackifying resin, achieved very poor anti-buoyancy (1425 μm) and impact resistance (660 mJ).

[0141] As can be seen from Comparative Examples 8-9, the use of block copolymers in the system can significantly improve the anti-buoyancy performance of the adhesive tape, but the peel strength (180° PA) is significantly reduced, which cannot meet the application requirements. This results in the acrylic rubber foam lacking sufficient tackiness, making it unsuitable for practical applications, and the impact resistance is not improved.

[0142] Surprisingly, however, when the tackifying resin of the poor-performing T105 type (terpene phenol resin) was combined with the block copolymer (component b) (e.g., Examples 1-5), a significant improvement in buoyancy resistance and impact resistance was obtained.

[0143] Taking Example 3, which uses a tackifying resin of type T105 and a block copolymer (component b), as an example, the anti-buoyancy is significantly improved compared to Comparative Examples 1 and 2, by approximately 2.5 times (compared to Comparative Example 1) and 31.3 times (compared to Comparative Example 2), respectively; and the impact resistance is also significantly improved, by approximately 42% (compared to Comparative Example 1) and 51% (compared to Comparative Example 2), respectively.

[0144] Comparative Examples 10 and 11 show that when non-terpene phenol tackifying resins are used, even when used in combination with block copolymers (component b), the poor compatibility between the resin and the block copolymers and acrylic resins leads to a loss of bonding performance, making it impossible to obtain excellent overall performance.

[0145] In summary, the acrylic rubber foam prepared by this invention, which contains both terpene phenolic resin and block copolymer (component b), significantly improves the buoyancy resistance and impact resistance of the foam core layer in double-sided tapes while maintaining excellent adhesion, making it ideal for use as a double-sided tape for bonding electronic mobile device components.

[0146] All documents mentioned in this invention are incorporated herein by reference as if each document were individually incorporated by reference. Furthermore, it should be understood that after reading the foregoing teachings of this invention, those skilled in the art can make various alterations or modifications to this invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A self-adhesive acrylic rubber foam, characterized by, The acrylic rubber foam comprises: (a) 80-120 parts by weight of acrylic resin; (b) 10-50 parts by weight of block copolymer; (c) 10-30 parts by weight of terpene phenol resin; and (d) 0.5-10 parts by weight of filler.

2. The acrylic rubber foam according to claim 1, wherein, The acrylic resin comprises: repeating unit A derived from a first monomer and repeating unit B derived from a second monomer.

3. The acrylic rubber foam as described in claim 2, characterized in that, The first monomer is selected from alkyl acrylate monomers; the second monomer is selected from carboxyl-containing olefinic unsaturated comonomers.

4. The acrylic rubber foam as described in claim 2, characterized in that, The acrylic resin comprises: 70-99 by weight of repeating unit A derived from a first monomer and 1-30 by weight of repeating unit B derived from a second monomer, based on the total weight of the acrylic resin.

5. The acrylic rubber foam as described in claim 1, characterized in that, The filler includes: hollow glass microspheres (HGS), hollow organic microspheres, or combinations thereof.

6. The acrylic rubber foam as described in claim 1, characterized in that, The acrylic rubber foam also includes additional additives selected from the group consisting of pigments, aging inhibitors, antioxidants, light stabilizers, UV protectants, flame retardants, or combinations thereof.

7. The acrylic rubber foam as described in claim 3, characterized in that, The acrylic rubber foam is obtained by UV polymerization of the first monomer and the second monomer in the presence of at least one crosslinking agent and a photoinitiator.

8. A double-sided adhesive tape, characterized in that, The double-sided tape comprises: 1) A rubber foam layer composed of acrylic rubber foam as described in claim 1; and 2) Two adhesive layers located on both sides of the rubber foam layer.

9. The use of the acrylic rubber foam as described in claim 1, characterized in that, The acrylic rubber foam is used as the core layer of double-sided tape or for bonding two substrates.

10. An assembly in which two substrates are bonded together by double-sided tape as claimed in claim 8, wherein the two substrates are preferably components of a mobile device.

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