A high-rigidity, impact-resistant foam masterbatch, tape, and preparation method thereof.

Abstract

This invention relates to a high-rigidity, impact-resistant foam masterbatch, tape, and its preparation method. The high-rigidity, impact-resistant foam masterbatch comprises a block copolymer, an acrylate monomer, a solvent, and an initiator. If the mass fraction of the block copolymer is designated as S and the mass fraction of the acrylate monomer is designated as B, then 1.5 ≤ B / S ≤ 5. The theoretical TG of the acrylate monomer after copolymerization is -40 to -20°C. The foam tape containing the foam masterbatch can be used as a cushioning material for bonding the bezels of large-size screens, achieving a stiffness of over 13 N / mm and possessing excellent impact resistance.

Description

Technical Field

[0001] This invention belongs to the field of foam tape, specifically, it relates to a high-rigidity, impact-resistant foam masterbatch, tape, and its preparation method. Background Technology

[0002] Foam tape, as a core component connecting the screen and the bezel, ensures a secure bond between the two. With the increasing prevalence of large-screen display technology in modern display devices and smart products (such as smartphones, tablets, and laptops), the importance of foam tape has become increasingly prominent. It not only needs excellent impact resistance to prevent damage from drops or collisions, but also needs sufficient rigidity to withstand the bending of the screen and bezel caused by the frequent opening and closing movements of these devices. Especially for large, flexible screens, the stress and deformation during bending are more significant. If the foam tape lacks sufficient rigidity, it is prone to cracking or even detaching during bending, leading to screen loosening or damage. Therefore, the design of foam tape must balance impact resistance and rigidity to meet the high standards of modern smart devices for connecting materials.

[0003] Existing impact-resistant foam tape technology:

[0004] CN117730128A provides a pressure-sensitive adhesive with good impact resistance and high internal strength, comprising a) at least 50% by weight of at least one poly(meth)acrylate based on the total weight of the pressure-sensitive adhesive; b) 15-35% by weight of a synthetic rubber component based on the total weight of the pressure-sensitive adhesive, which comprises at least one vinyl aromatic butadiene block copolymer and at least one vinyl aromatic isoprene block copolymer; and c) at least one tackifier resin compatible with the synthetic rubber component.

[0005] KR1020247026664 discloses an impact-resistant adhesive that uses a toughening component with a core-shell structure to improve the impact resistance of polyacrylate adhesives, especially in side impact tests.

[0006] However, none of the aforementioned patents address how to achieve the required stiffness in foam tape. To ensure that foam tape design balances impact resistance and stiffness, this invention proposes a high-stiffness, impact-resistant foam masterbatch, tape, and its preparation method. This invention will drive further development of large-screen display technology. Summary of the Invention

[0007] In view of the current state of technology, the purpose of this invention is to provide a high-rigidity, impact-resistant foam masterbatch, tape, and its preparation method. This foam tape can be used as a cushioning material for bonding the bezels of large-size screens, achieving a stiffness of over 13 N / mm and possessing excellent impact resistance.

[0008] To address the aforementioned technical problems, the first aspect of the present invention provides the following technical solution:

[0009] A high-rigidity, impact-resistant foam masterbatch is characterized by comprising a block copolymer, an acrylate monomer, a solvent, and an initiator; if the mass fraction of the block copolymer is set as S and the mass fraction of the acrylate monomer is set as B, then 1.5 ≤ B / S ≤ 5, and the theoretical TG of the acrylate monomer after copolymerization is -40 to -20℃.

[0010] Preferably, the solid content of the high-rigidity impact-resistant foam masterbatch is 20-50%, and the solvent is set as R parts by mass, and the initiator is set as Y parts by mass; then: 20% ≤ (S+B+Y) / (S+B+Y+R) ≤ 50%.

[0011] Preferably, the block copolymer has a styrene content > 20%;

[0012] More preferably, the block copolymer has a star-shaped structure.

[0013] Preferably, the foam masterbatch is prepared by first performing acrylate graft-modified block copolymerization and then acrylate copolymerization in the same reaction vessel.

[0014] Preferably, the block copolymer is one or more of SBS, SIS, and SEBS.

[0015] Preferably, the acrylate monomer is one or more of the following: acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, n-butyl acrylate, isobutyl acrylate, isooctyl acrylate, isoborneol acrylate, isoborneol methacrylate, cyclohexyl methacrylate, hydroxybutyl acrylate, ureaacrylate, ethyl diethylene glycol acrylate, and tert-butyl acrylate.

[0016] Preferably, the initiator is a peroxide and / or an azo compound; for example, benzoyl peroxide, tert-butyl peroxide terephthalate, tert-butyl peroxypentanoate, tert-butyl hydroperoxide, tert-butyl peroxybenzoate, azobisisobutyronitrile, azobisisoheptanenitrile, and azobisisovalerate. More preferably, the initiator is azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO).

[0017] Preferably, the solubility parameter of the first solvent is 7.6-9.8, and it can be one or more of toluene, xylene, n-butyl acetate, methyl isobutyl ketone, isobutyl acetate, cyclohexane, tert-butyl acetate, and ethyl acetate.

[0018] Furthermore, without affecting the desired effect of the present invention, other additives may be added to the high-rigidity impact-resistant foam masterbatch. For example, chain transfer agents, antioxidants, flame retardants, etc.

[0019] Preferably, the chain transfer agent is one or more of isopropanol and dodecyl mercaptan; the mass fraction of the chain transfer agent is set as L, where 0.001‰≤L / S≤1‰.

[0020] A second aspect of this invention provides a method for preparing a high-rigidity, impact-resistant foam masterbatch, comprising the following steps:

[0021] In a nitrogen atmosphere, solvent one and all block copolymers are added sequentially to the reactor to make the solid content of the block copolymers 10-30%, and the mixture is heated and refluxed for 5-10 minutes.

[0022] Mix 0.2B parts by weight of acrylic monomer and 0.0001 to 0.01S parts by weight of initiator evenly, remove oxygen with N2, and add to the reactor. Continue to react for 3-5 hours.

[0023] Mix 0.8B parts by weight of acrylic monomer, 0.00008B to 0.008B parts by weight of initiator, and 0.8B parts by weight of solvent evenly. After deoxygenation with N2, add the mixture dropwise into the reactor over 1-1.5 hours and react for 1-2 hours.

[0024] Add 0.00004B to 0.004B parts by weight of initiator every 1 hour until all the remaining initiator is added. After reacting for 1-2 hours, add the remaining solvent and cool to room temperature to obtain high-rigidity impact-resistant foam masterbatch.

[0025] A third aspect of the present invention is to provide a method for preparing the high-rigidity impact-resistant foam tape, characterized in that it comprises, by weight, 100 parts of the above-mentioned foam masterbatch, 0.1-5 parts of foaming agent, 0-300 parts of tackifying resin, 0.1-5 parts of curing agent, and 0-400 parts of solvent II.

[0026] Except for solvent 2, all other components are calculated as solid components.

[0027] Preferably, the curing agent is one or more of isocyanate curing agents, epoxy curing agents, and metal salt curing agents.

[0028] More preferably, the curing agent is a combination of an epoxy curing agent and a metal salt curing agent.

[0029] Preferably, the second solvent is one or more of toluene, ethyl acetate, heptane, butyl acetate, and butanone.

[0030] Preferably, the foaming agent is one or more of foaming microspheres, hydrocarbon foaming agents, and carbon dioxide foaming agents;

[0031] Preferably, the tackifying resin is one or more of terpenes, rosins, esterified rosins, and petroleum resins.

[0032] A fourth aspect of the present invention provides a method for preparing a high-rigidity, impact-resistant foam tape, comprising the following steps:

[0033] S1: Add the materials to the container in the following order: dissolve solvent II and tackifying resin thoroughly until no particles remain; then add foam masterbatch and stir at high speed for 10-30 minutes; add foaming agent and curing agent, mix evenly, and adjust the solid content to 20-35% with solvent II to prepare the coating liquid;

[0034] S2: After filtering and degassing the coating solution prepared above, it is evenly coated onto the release film. After drying, foaming, and laminating, a high-rigidity impact-resistant foam tape is obtained.

[0035] Preferably, the coating liquid is filtered using a three-core 10µm filter cartridge.

[0036] Preferably, the drying process is as follows: the above-mentioned coating liquid is evenly coated onto the release film and continuously passed through a coating machine containing 7 drying ovens, and continuously heated and dried to form a high-rigidity, impact-resistant foam tape. The temperatures of the first stage are 60–70°C, the second stage 70–85°C, the third stage 85–110°C, the fourth stage 110–155°C, the fifth stage 110–155°C, the sixth stage 130–110°C, and the seventh stage 110–90°C.

[0037] The fifth aspect of the present invention provides an application of a high-rigidity impact-resistant foam tape, characterized in that the high-rigidity impact-resistant foam tape described above or the high-rigidity impact-resistant foam tape prepared by the above method is applied to modern display and smart devices.

[0038] The modern display and smart devices mentioned are devices with display technology, intelligent functions, and the ability to enable user interaction, such as: televisions, computers, tablets, learning machines, smart wearable devices, in-vehicle displays, health monitoring devices, smartwatches, fitness trackers, smart glasses, smart home screens, AR devices, VR devices, smart robots, smart displays, motion-sensing interactive devices, etc.

[0039] Unless otherwise specified, "room temperature" in this invention refers to 23°C.

[0040] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0041] 1. Foam masterbatch is prepared by first performing acrylate graft-modified block copolymerization in the same reaction vessel, followed by acrylate copolymerization. The block copolymer molecular chains and polyacrylate molecular chains are intertwined, inhibiting delamination. This is beneficial for solvent coating and avoids phase separation during the standing process of the coating liquid, which would cause delamination of thicker foam tape.

[0042] 2. Polyacrylate undergoes micro-crosslinking through a curing agent, forming an interpenetrating network structure with block copolymers, which increases the stiffness and impact resistance of the adhesive.

[0043] 3. The theoretical TG of the acrylate monomers after individual copolymerization is -40 to -20°C, which can ensure that the adhesion, impact resistance and stiffness of the foam tape meet the application requirements. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of a stiffness test;

[0045] Figure 2 This is a schematic diagram of an impact resistance test. Detailed Implementation

[0046] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] The raw materials used in the following embodiments are shown in Table 1:

[0048] Table 1 Composition of high-rigidity impact-resistant foam adhesive layer

[0049]

[0050]

[0051] Example 1

[0052] Preparation of foam masterbatch

[0053] According to the mass fraction, the composition of the foam masterbatch is as follows, wherein the theoretical TG after copolymerization of the acrylate monomers is -38.78℃;

[0054]

[0055] Prepare foam masterbatch according to the following steps:

[0056] 1. In a N2 atmosphere, 200 parts of toluene are placed in a 50L reactor. While stirring, 50 parts of SBS D1118 are added. The system temperature is controlled to rise to 82℃ and refluxed for 5 minutes.

[0057] 2. Mix 44 parts of acrylic monomer (1.32 parts of methacrylic acid, 2.2 parts of butyl acrylate, 11 parts of methyl methacrylate, and 29.48 parts of isooctyl acrylate) and 0.05 parts of BPO evenly, deoxygenate with N2 for 30 minutes, and then add it into the reactor all at once.

[0058] 3. Maintain the system at 82℃ and continue the reaction for 4 hours, then cool the system to reach 72℃.

[0059] 4. Mix the remaining 176 parts of acrylic acid monomer, 0.11 parts of AIBN, and 176 parts of toluene evenly, deoxygenate with N2 for 30 minutes, and then add it dropwise into the reaction vessel over a period of 1.5 hours.

[0060] 5. Maintain the system at 72℃ and react for 2 hours. Then, add 0.055 parts of AIBN every hour for a total of 3 times.

[0061] 6. After the last addition of AIBN, react for 1.5 hours, then add the remaining toluene to cool down to room temperature.

[0062] Preparation of foam tape

[0063] The composition of the foam tape coating solution, by weight, is as follows:

[0064]

[0065] Prepare foam tape according to the following steps:

[0066] 1. Add the materials to the container in the following order: Dissolve the solvent and tackifying resin in a 1:1 ratio at 500 rpm until no particles remain; then add the foam masterbatch and stir at 1200 rpm for 20 minutes; add the foaming agent and curing agent and mix evenly at 500 rpm, and adjust the solid content to 25±1% with solvent to prepare the coating liquid;

[0067] 2. The coating liquid prepared above is degassed under vacuum, filtered through a three-core 10um filter element, and then uniformly coated onto the release film.

[0068] 3. The coated release film is continuously heated, dried, and foamed in a coating machine containing 7 drying ovens to form a high-rigidity, impact-resistant foam tape with a thickness of 200µm. The temperatures are as follows: first stage 60–70℃, second stage 70–85℃, third stage 85–110℃, fourth stage 110–155℃, fifth stage 110–155℃, sixth stage 130–110℃, and seventh stage 110–90℃.

[0069] Example 2

[0070] Preparation of foam masterbatch

[0071] According to the mass fraction, the composition of the foam masterbatch is as follows, wherein the theoretical TG after copolymerization of the acrylate monomers is -38.78℃;

[0072]

[0073] Prepare foam masterbatch according to the following steps:

[0074] 1. In a N2 atmosphere, 200 parts of toluene are placed in a 50L reactor. While stirring, 50 parts of SBS D1116 are added. The system temperature is controlled to rise to 82℃ and refluxed for 5 minutes.

[0075] 2. Mix 44 parts of acrylic monomer (1.32 parts of methacrylic acid, 2.2 parts of butyl acrylate, 11 parts of methyl methacrylate, and 29.48 parts of isooctyl acrylate) and 0.05 parts of BPO evenly, deoxygenate with N2 for 30 minutes, and then add it into the reactor all at once.

[0076] 3. Maintain the system at 82℃ and continue the reaction for 4 hours, then cool the system to reach 72℃.

[0077] 4. Mix the remaining 176 parts of acrylic acid monomer, 0.11 parts of AIBN, and 176 parts of toluene evenly, deoxygenate with N2 for 30 minutes, and then add it dropwise into the reaction vessel over a period of 1.5 hours.

[0078] 5. Maintain the system at 72℃ and react for 2 hours. Then, add 0.055 parts of AIBN every hour for a total of 3 times.

[0079] 6. After the last addition of AIBN, react for 1.5 hours, then add the remaining toluene to cool down to room temperature.

[0080] Preparation of foam tape

[0081] The composition of the foam tape coating solution, by weight, is as follows:

[0082]

[0083]

[0084] Prepare foam tape according to the following steps:

[0085] 1. Add the materials to the container in the following order: Dissolve the solvent and tackifying resin in a 1:1 ratio at 500 rpm until no particles remain; then add the foam masterbatch and stir at 1200 rpm for 20 minutes; add the foaming agent and curing agent and mix evenly at 500 rpm, and adjust the solid content to 25±1% with solvent to prepare the coating liquid;

[0086] 2. The coating liquid prepared above is degassed under vacuum, filtered through a three-core 10um filter element, and then uniformly coated onto the release film.

[0087] 3. The coated release film is continuously heated, dried, and foamed in a coating machine containing 7 drying ovens to form a high-rigidity, impact-resistant foam tape with a thickness of 200µm. The temperatures of the first section are 60–70℃, the second section is 70–85℃, the third section is 85–110℃, the fourth section is 110–155℃, the fifth section is 110–155℃, the sixth section is 130–110℃, and the seventh section is 110–90℃.

[0088] Example 3

[0089] Preparation of foam masterbatch

[0090] According to the mass fraction, the composition of the foam masterbatch is as follows, wherein the theoretical TG after copolymerization of the acrylate monomers is -38.78℃;

[0091]

[0092] Prepare foam masterbatch according to the following steps:

[0093] 1. In a N2 atmosphere, 200 parts of toluene are placed in a 50L reactor. While stirring, 50 parts of VECTOR4213 are added. The system temperature is controlled to rise to 82℃ and refluxed for 5 minutes.

[0094] 2. Mix 44 parts of acrylic monomer (1.32 parts of methacrylic acid, 2.2 parts of butyl acrylate, 11 parts of methyl methacrylate, and 29.48 parts of isooctyl acrylate) and 0.05 parts of BPO evenly, deoxygenate with N2 for 30 minutes, and then add it into the reactor all at once.

[0095] 3. Maintain the system at 82℃ and continue the reaction for 4 hours, then cool the system to reach 72℃.

[0096] 4. Mix the remaining 176 parts of acrylic acid monomer, 0.11 parts of AIBN, and 176 parts of toluene evenly, deoxygenate with N2 for 30 minutes, and then add it dropwise into the reaction vessel over a period of 1.5 hours.

[0097] 5. Maintain the system at 72℃ and react for 2 hours. Then, add 0.055 parts of AIBN every hour for a total of 3 times.

[0098] 6. After the last addition of AIBN, react for 1.5 hours, then add the remaining toluene to cool down to room temperature.

[0099] Preparation of foam tape

[0100] The composition of the foam tape coating solution, by weight, is as follows:

[0101]

[0102] Prepare foam tape according to the following steps:

[0103] 1. Add the materials to the container in the following order: Dissolve the solvent and tackifying resin in a 1:1 ratio at 500 rpm until no particles remain; then add the foam masterbatch and stir at 1200 rpm for 20 minutes; add the foaming agent and curing agent and mix evenly at 500 rpm, and adjust the solid content to 25±1% with solvent to prepare the coating liquid;

[0104] 2. The coating liquid prepared above is degassed under vacuum, filtered through a three-core 10um filter element, and then uniformly coated onto the release film.

[0105] 3. The coated release film is continuously heated, dried, and foamed in a coating machine containing 7 drying ovens to form a high-rigidity, impact-resistant foam tape with a thickness of 200µm. The temperatures of the first section are 60–70℃, the second section is 70–85℃, the third section is 85–110℃, the fourth section is 110–155℃, the fifth section is 110–155℃, the sixth section is 130–110℃, and the seventh section is 110–90℃.

[0106] Example 4

[0107] Preparation of foam masterbatch

[0108] According to the mass fraction, the composition of the foam masterbatch is as follows, wherein the theoretical TG after copolymerization of the acrylate monomers is -38.78℃;

[0109]

[0110] Prepare foam masterbatch according to the following steps:

[0111] 1. In a N2 atmosphere, 200 parts of toluene are placed in a 50L reactor. While stirring, 50 parts of SBS D1118 are added. The system temperature is controlled to rise to 82℃ and refluxed for 5 minutes.

[0112] 2. Mix 22 parts of acrylic monomer (0.66 parts of methacrylic acid, 1.1 parts of butyl acrylate, 5.5 parts of methyl methacrylate, 14.74 parts of isooctyl acrylate) and 0.05 parts of BPO evenly, deoxygenate with N2 for 30 minutes, and then add it into the reactor all at once.

[0113] 3. Maintain the system at 82℃ and continue the reaction for 4 hours, then cool the system to reach 72℃.

[0114] 4. Mix the remaining 88 parts of acrylic acid monomer, 0.055 parts of AIBN, and 88 parts of toluene evenly, deoxygenate with N2 for 30 minutes, and then add it dropwise into the reaction vessel over a period of 1.5 hours.

[0115] 5. Maintain the system at 72℃ and react for 2 hours. Then, add 0.0275 parts of AIBN every hour for a total of 3 times.

[0116] 6. After the last addition of AIBN, react for 1.5 hours, then add the remaining toluene to cool down to room temperature.

[0117] Preparation of foam tape

[0118] The composition of the foam tape coating solution, by weight, is as follows:

[0119]

[0120] Prepare foam tape according to the following steps:

[0121] 1. Add the materials to the container in the following order: Dissolve the solvent and tackifying resin in a 1:1 ratio at 500 rpm until no particles remain; then add the foam masterbatch and stir at 1200 rpm for 20 minutes; add the foaming agent and curing agent and mix evenly at 500 rpm, and adjust the solid content to 25±1% with solvent to prepare the coating liquid;

[0122] 2. The coating liquid prepared above is degassed under vacuum, filtered through a three-core 10um filter element, and then uniformly coated onto the release film.

[0123] 3. The coated release film is continuously heated, dried, and foamed in a coating machine containing 7 drying ovens to form a high-rigidity, impact-resistant foam tape with a thickness of 200µm. The temperatures of the first section are 60–70℃, the second section is 70–85℃, the third section is 85–110℃, the fourth section is 110–155℃, the fifth section is 110–155℃, the sixth section is 130–110℃, and the seventh section is 110–90℃.

[0124] Example 5

[0125] Preparation of foam masterbatch

[0126] According to the mass fraction, the composition of the foam masterbatch is as follows, wherein the theoretical TG after copolymerization of the acrylate monomers is -19.54℃;

[0127]

[0128]

[0129] Prepare foam masterbatch according to the following steps:

[0130] 1. In a N2 atmosphere, 200 parts of toluene are placed in a 50L reactor. While stirring, 50 parts of SBS D1118 are added. The system temperature is controlled to rise to 82℃ and refluxed for 5 minutes.

[0131] 2. Mix 44 parts of acrylic monomer (1.32 parts of methacrylic acid, 17.6 parts of methyl methacrylate, 25.08 parts of isooctyl acrylate) and 0.05 parts of BPO evenly, deoxygenate with N2 for 30 minutes, and then add it into the reactor all at once;

[0132] 3. Maintain the system at 82℃ and continue the reaction for 4 hours, then cool the system to reach 72℃.

[0133] 4. Mix the remaining 176 parts of acrylic acid monomer, 0.11 parts of AIBN, and 176 parts of toluene evenly, deoxygenate with N2 for 30 minutes, and then add it dropwise into the reaction vessel over a period of 1.5 hours.

[0134] 5. Maintain the system at 72℃ and react for 2 hours. Then, add 0.055 parts of AIBN every hour for a total of 3 times.

[0135] 6. After the last addition of AIBN, react for 1.5 hours, then add the remaining toluene to cool down to room temperature.

[0136] Preparation of foam tape

[0137] The composition of the foam tape coating solution, by weight, is as follows:

[0138]

[0139] Prepare foam tape according to the following steps:

[0140] 1. Add the materials to the container in the following order: Dissolve the solvent and tackifying resin in a 1:1 ratio at 500 rpm until no particles remain; then add the foam masterbatch and stir at 1200 rpm for 20 minutes; add the foaming agent and curing agent and mix evenly at 500 rpm, and adjust the solid content to 25±1% with solvent to prepare the coating liquid;

[0141] 2. The coating liquid prepared above is degassed under vacuum, filtered through a three-core 10um filter element, and then uniformly coated onto the release film.

[0142] 3. The coated release film is continuously heated, dried, and foamed in a coating machine containing 7 drying ovens to form a high-rigidity, impact-resistant foam tape with a thickness of 200µm. The temperatures are as follows: first stage 60–70℃, second stage 70–85℃, third stage 85–110℃, fourth stage 110–155℃, fifth stage 110–155℃, sixth stage 130–110℃, and seventh stage 110–90℃.

[0143] Comparative Example 1

[0144] Preparation of foam masterbatch

[0145] The foam masterbatch was prepared using the same method as in Example 1, except that the mass ratio of acrylate monomers to block copolymers in the foam masterbatch composition was B / S = 1, which was not in the range of 1.5 to 5. Specifically, the composition of the foam masterbatch by mass parts is as follows:

[0146]

[0147] Foam tape preparation

[0148] Foam tape was prepared using the same method as in Example 1. The tape composition is as follows:

[0149] The composition of the foam tape coating solution, by weight, is as follows:

[0150]

[0151]

[0152] Comparative Example 2

[0153] Preparation of foam masterbatch

[0154] The foam masterbatch was prepared using the same method as in Example 1, except that the mass ratio of acrylate monomers to block copolymers in the foam masterbatch composition was B / S = 6, which is not within the range of 1.5 to 5. Specifically, the composition of the foam masterbatch by mass parts is as follows:

[0155]

[0156] Preparation of foam tape

[0157] Foam tape was prepared using the same method as in Example 1. The tape composition is as follows:

[0158] The composition of the foam tape coating solution, by weight, is as follows:

[0159]

[0160] Comparative Example 3

[0161] Preparation of foam masterbatch

[0162] The foam masterbatch was prepared using the same method as in Example 1, except that the theoretical TG of the acrylate monomers in the foam masterbatch after individual copolymerization is 0.69℃, which is not within the range of -40 to -20℃. Specifically, the composition of the foam masterbatch by weight is as follows:

[0163]

[0164] Preparation of foam tape

[0165] Foam tape was prepared using the same method as in Example 1. The tape composition is as follows:

[0166] The composition of the foam tape coating solution, by weight, is as follows:

[0167]

[0168] Comparative Example 4

[0169] Preparation of foam masterbatch

[0170] Foam masterbatch was prepared using the same method as in Example 1, except that the theoretical TG of the acrylate monomers in the foam masterbatch after individual copolymerization is -50.66°C, which is not within the range of -40 to -20°C. Specifically, the composition of the foam masterbatch by weight is as follows:

[0171]

[0172]

[0173] Preparation of foam tape

[0174] Foam tape was prepared using the same method as in Example 1. The tape composition is as follows:

[0175] The composition of the foam tape coating solution, by weight, is as follows:

[0176]

[0177] Comparative Example 5

[0178] Preparation of foam masterbatch

[0179] The foam masterbatch was prepared using the same method as in Example 1, except that the styrene content of the block copolymer SIS3421 used was 14%. Specifically, the composition of the foam masterbatch by weight is as follows:

[0180]

[0181]

[0182] Preparation of foam tape

[0183] Foam tape was prepared using the same method as in Example 1. The composition of the foam tape coating solution, by weight, is as follows:

[0184]

[0185] Comparative Example 6

[0186] Unlike in Example 1, the acrylic graft modified block copolymer and acrylic acid copolymer were copolymerized in different reactors, and then the two were mixed evenly by blending before adding tackifying resin and other additives to prepare foam tape coating liquid.

[0187] Preparation of acrylate graft-modified block copolymers

[0188]

[0189] 1. In a N2 atmosphere, 200 parts of toluene are placed in a 50L reactor, and 50 parts of SBSD1118 are added while stirring. The system temperature is controlled to rise to 82℃ and refluxed for 5 minutes.

[0190] 2. Mix 44 parts of acrylic monomer (1.32 parts of methacrylic acid, 2.2 parts of butyl acrylate, 11 parts of methyl methacrylate, and 29.48 parts of isooctyl acrylate) with 0.05 parts of BPO until homogeneous, deoxygenate with N2 for 30 minutes, and then add it into the reactor all at once.

[0191] 3. Maintain the system at 82°C and continue the reaction for 4 hours, then cool down to obtain the acrylic acid grafted modified block copolymer.

[0192] Preparation of acrylate adhesives

[0193]

[0194] 1. In a N2 atmosphere, mix 176 parts of acrylic monomer and 176 parts of toluene evenly, deoxygenate with N2 for 30 min, add to the reactor, control the system temperature to 72℃, and reflux for 5 min.

[0195] 2. Add 0.11 parts of AIBN, observe the system, and record the time t=0 after small bubbles are generated;

[0196] 3. Maintain the system at 72℃ and react for 2 hours. Then, add 0.055 parts of AIBN every hour for a total of 3 times.

[0197] 4. After the last addition of AIBN, react for 1.5 hours, then add the remaining toluene to cool down to room temperature.

[0198] Preparation of foam tape

[0199] The composition of the foam tape coating solution, by weight, is as follows:

[0200]

[0201] Prepare foam tape according to the following steps:

[0202] 1. Add the materials to the container in the following order: Dissolve the solvent and tackifying resin in a 1:1 ratio at 500 rpm until no particles remain; then add the acrylate graft-modified block copolymer and acrylate adhesive and stir at 1200 rpm for 20 minutes; add the foaming agent and curing agent and mix evenly at 500 rpm, and adjust the solid content to 25±1% with solvent to prepare the coating liquid;

[0203] 2. The coating liquid prepared above is degassed under vacuum, filtered through a three-core 10um filter element, and then uniformly coated onto the release film.

[0204] 3. The coated release film is continuously heated, dried, and foamed in a coating machine containing 7 drying ovens to form a high-rigidity, impact-resistant foam tape with a thickness of 200µm. The temperatures of the first section are 60–70℃, the second section is 70–85℃, the third section is 85–110℃, the fourth section is 110–155℃, the fifth section is 110–155℃, the sixth section is 130–110℃, and the seventh section is 110–90℃.

[0205] The performance tests of the foam tapes prepared in Examples 1-5 and Comparative Examples 1-6 are compared in the table below:

[0206]

[0207] Test item description:

[0208] 1. Peel force test on SUS steel plate at 180°

[0209] The test was conducted in accordance with the standard "Test Method for Peel Strength of Adhesive Tapes" (GB / T2792-2014).

[0210] 2. Stiffness test

[0211] (1) Prepare two 6061-T6 aluminum plates with a size of 2mm*12mm*200mm and wipe them clean with isopropanol;

[0212] (2) Attach foam tape to one of the aluminum plates and cover it with another aluminum plate. Press the two plates back and forth three times using a 2KG roller. After leaving it at room temperature for 20 minutes, test it. Figure 1 As shown;

[0213] (3) Press Figure 1 As shown, the spline was placed on the fixture, and the pressing speed was set to 0.05 mm / s. The vertical displacement w1 of the spline bending downward at 6.66 N and the vertical displacement w2 of the spline bending downward at 20 N were recorded.

[0214] (4) Calculate stiffness = 13.34 / (w2-w1).

[0215] 3. Impact resistance test

[0216] (1) Cut the foam tape into a square-shaped pattern with an outer side length of 24.5mm and an inner side length of 20.5mm;

[0217] (2) Figure 2 As shown, the square sample was attached to the square stainless steel frame (outer side length 40mm, inner side length 20mm), and then the square stainless steel cover plate (side length 24.5mm) was attached to the other side of the square sample. A force of 62N was applied for 10s and the sample was left at room temperature for 48h.

[0218] (3) A penetrating impact with a total impact energy of 30.4J and a height of 205mm was performed, and the total energy absorbed during the damage was recorded.

[0219] Conclusion: The method of preparing foam masterbatch by first grafting acrylic acid to modify the block copolymer and then copolymerizing acrylic acid in the same reactor can avoid phase separation during the settling process of the coating liquid. At the same time, the design and specification of the theoretical TG and content of acrylate monomers can ensure the adhesion, impact resistance and stiffness of the foam tape and meet the application requirements.

[0220] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A high-rigidity impact-resistant foam masterbatch, characterized by, The foam masterbatch is prepared by first grafting modification of acrylate block copolymer and then acrylate copolymerization in the same reaction vessel; it comprises block copolymer, acrylate monomer, solvent I, initiator; the mass fraction of the block copolymer is denoted as S, and the mass fraction of the acrylate monomer is denoted as B, then 1.5≤B / S≤5; the styrene content of the block copolymer is >20%, and it is one or more of SBS, SIS and SEBS; the theoretical TG of the acrylate monomer after individual copolymerization is -40~-20℃.

2. The high stiffness impact resistant foam precursors of claim 1, wherein, The solid content of the high-rigidity impact-resistant foam masterbatch is 20~50%, the mass fraction of the solvent I is denoted as R, and the mass fraction of the initiator is denoted as Y; then 20%≤(S+B+Y) / (S+B+Y+R)≤50%. 3.The high-rigidity impact-resistant foam masterbatch according to claim 1, characterized in that, the acrylate monomer is one or more of acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, n-butyl acrylate, isobutyl acrylate, isooctyl acrylate, isobornyl acrylate, isobornyl methacrylate, cyclohexyl methacrylate, hydroxybutyl acrylate and t-butyl acrylate; the initiator is a peroxide and / or an azo compound; the solubility parameter of the solvent I is 7.6-9.

8. 4.A method for preparing the high-rigidity impact-resistant foam masterbatch according to any one of claims 1-3, comprising the following steps: in a N2 atmosphere, the solvent I and all the block copolymers are sequentially added into a reaction kettle, so that the solid content of the block copolymers is 10~30%, and the temperature is raised to reflux for 5-10 min; 0.2B mass fractions of the acrylate monomer and 0.0001S~0.01S mass fractions of the initiator are uniformly mixed, and after N2 deoxygenation, they are added into the reaction kettle for continuous reaction for 3-5 h; 0.8B mass fractions of the acrylate monomer, 0.00008B~0.008B mass fractions of the initiator and 0.8B mass fractions of the solvent I are uniformly mixed, and after N2 deoxygenation, they are added dropwise into the reaction kettle for 1-1.5 h, and reacted for 1-2 h; every 1 h, 0.00004B~0.004B mass fractions of the initiator are added until all the remaining initiator is added, and after reaction for 1-2 h, the remaining solvent is added, and the temperature is cooled to room temperature, thereby obtaining the high-rigidity impact-resistant foam masterbatch.

5. A high stiffness impact resistant foam tape, characterized by, by mass, it comprises 100 parts of the foam masterbatch according to any one of claims 1-3, 0.1-5 parts of a foaming agent, 0-300 parts of tackifying resin, 0.1-5 parts of a curing agent and 0-400 parts of a solvent II; all the components except the solvent II are calculated as solid components.

6. The high stiffness impact resistant foam tape of claim 5, wherein, the curing agent is one or more of isocyanate curing agent, epoxy curing agent and metal salt curing agent; the solvent II is one or more of toluene, ethyl acetate, heptane, butyl acetate and butanone; the foaming agent is one or more of foaming microspheres, hydrocarbon foaming agent and carbon dioxide foaming agent; the tackifying resin is one or two of terpenes, rosin, esterified rosin and petroleum resin.

7. The method for preparing the high-rigidity impact-resistant foam tape according to any one of claims 5-6, comprising the following steps: S1: adding materials in the following order in a container: dissolving the solvent two and tackifying resin to no particle residue; then adding the foam base glue, stirring at high speed for 10-30 minutes; adding the foaming agent and curing agent, mixing uniformly and adjusting the solid content to 20-35% with the solvent two to prepare a coating liquid; S2: after filtering and defoaming the prepared coating liquid, uniformly coating it on a release film, drying, foaming and laminating to obtain the high-rigidity impact-resistant foam tape.

8. Use of a high stiffness impact resistant foam tape, characterized in that, The high-rigidity impact-resistant foam tape according to any one of claims 5-6 or prepared according to the method of claim 7 is applied to modern display and smart devices.

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