Acid-free, durable high-temperature-resistant and high-adhesive-force pressure-sensitive adhesive tape and preparation method thereof

Abstract

The invention discloses an acid-free, durable high-temperature-resistant and high-adhesive-force pressure-sensitive adhesive tape and a preparation method thereof. The adhesive tape comprises an adhesive layer, and a PET base material layer and a release layer are attached to the two sides of the adhesive layer respectively; the adhesive layer is prepared from the following raw material components in percentage by mass: 80 to 90 percent of polyacrylate; 0.3-0.4% of a curing agent and 10-20% of tackifying resin. The performance of the pressure-sensitive adhesive tape reaches the initial adhesion (rolling ball method) 13 #, the stripping force reaches 1997 gf / 25 mm (SUS) steel plate, the 180-degree retention force (80 DEG C, 30 days) 0-1 mm, the T-type 90-degree retention force (50 DEG C, 30 days) 5-6 mm, the acid value is close to zero, and the pressure-sensitive adhesive tape is friendly to an adhered object and durable in viscosity.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure-sensitive adhesive tapes, and in particular to an acid-free, high-temperature-resistant, high-adhesion pressure-sensitive adhesive tape and a preparation method thereof. Background Art

[0002] Pressure-sensitive tape is an adhesive material that bonds with light pressure without the need for solvents, heating, or curing. It is widely used in electronics, automotive, packaging, and medical fields.

[0003] Currently, high-adhesion pressure-sensitive adhesive tapes almost all use a synthetic formula containing acid monomers. During the synthetic manufacturing process of acrylic adhesives, even if the acid monomers are fully polymerized into the molecular chain of the acrylate polymer, the polymerization process is only a free radical polymerization that consumes monoolefinic bonds, and the carboxyl groups in the acid monomers do not react. Therefore, the adhesive polymer still has acidity. After absorbing moisture from the air, the pressure-sensitive adhesive made with this will still ionize hydrogen ions and become corrosive to acids. In addition, in actual use, electronic components generate a lot of heat during operation. At high temperatures, the adhesive layer is prone to softening, cohesive failure, or deformation of the substrate, resulting in poor durability. This places higher demands on the high-temperature resistance of pressure-sensitive adhesives. Currently, there is still much room for improvement in the durability of the high-temperature resistance of pressure-sensitive adhesives, which need to maintain strong adhesion even at high temperatures for a long time.

[0004] Therefore, there is an urgent need to develop a pressure-sensitive adhesive tape that is acid-free, resistant to high temperatures, and has high adhesion. Summary of the Invention

[0005] The present invention aims to solve the problems of current pressure-sensitive adhesive tapes containing acid, not being resistant to persistent high temperatures and having low adhesion, and to provide a pressure-sensitive adhesive tape that is acid-free, resistant to persistent high temperatures and has high adhesion, and a preparation method thereof.

[0006] In order to achieve the above technical objectives, the technical solution provided by the present invention is: An acid-free, high-temperature-resistant, high-adhesion pressure-sensitive tape comprises an adhesive layer, with a PET substrate layer and a release layer attached to both sides of the adhesive layer. The adhesive layer comprises the following raw material components by mass percentage: 80-90% polyacrylate; 0.3-0.4% curing agent; and 10-20% tackifying resin.

[0007] Specifically, the thickness of the adhesive layer and the PET substrate layer are both 25 μm, and the thickness of the release layer is 36 μm.

[0008] Furthermore, the polyacrylate comprises the following components by weight: 30-40 parts of soft monomer, 2-5 parts of hard monomer, 0-5 parts of carboxyl functional monomer, 0-5 parts of amide functional monomer, 0.5-1 parts of hydroxyl functional monomer, 0.1-0.3 parts of initiator, and 60-65 parts of mixed solvent.

[0009] Furthermore, the curing agent is an isocyanate curing agent.

[0010] Furthermore, the tackifying resin comprises one or more of α-terpene resin, β-terpene resin, and terpene phenolic resin.

[0011] Furthermore, the soft monomer includes one or more of n-butyl acrylate, ethyl acrylate, and isooctyl acrylate.

[0012] Specifically, the soft monomer functions to produce a polymer with a lower Tg and initial tack properties, resulting in good anchoring to the substrate.

[0013] Furthermore, the hard monomer comprises one or more of methyl acrylate, vinyl acetate, and isobornyl.

[0014] Specifically, the hard monomer functions to produce a homopolymer with a higher glass transition temperature (Tg), and can copolymerize with the soft monomer to produce better cohesion, resulting in a significant improvement in bonding strength.

[0015] Furthermore, the carboxyl functional monomer comprises one or more of acrylic acid, methacrylic acid, and butenedioic acid.

[0016] Furthermore, the amide-containing functional monomer includes one or more of acrylamide and methylbenzamide.

[0017] Furthermore, the hydroxyl functional monomer includes one or more of hydroxypropyl acrylate, hydroxyethyl acrylate, and 4-hydroxybutyl acrylate.

[0018] Specifically, the carboxyl functional monomer, the amide functional monomer, and the hydroxyl functional monomer affect the molecular weight of the polymer, thereby affecting the temperature resistance, peeling force, and initial adhesion of the adhesive layer.

[0019] Furthermore, the mixed solvent comprises one or more of ethyl acetate, butanone, and acetone.

[0020] Specifically, the mass ratio of ethyl acetate to butanone is 3:2.

[0021] Specifically, the solvent induces the decomposition of the initiator, and chain radicals react with the solvent through chain transfer. Both of these effects can affect the polymerization rate and molecular weight. Toluene is highly harmful to humans and the environment, while the more environmentally friendly ethyl acetate, when used alone as a solvent, can induce excessive polymer viscosity due to its induction of the initiator, ultimately leading to gelation. Furthermore, excessive ethyl acetate can lead to excessive viscosity, while excessive butanone can cause premature chain termination, resulting in a low molecular weight and low viscosity. Therefore, the present invention utilizes a mixed solvent (ethyl acetate:butanone in a ratio of 3:2) to achieve a synergistic effect, ensuring a homogeneous polymerization system during the reaction. This helps reduce polymer viscosity, mitigate the gelation effect, and dissipate the heat of polymerization.

[0022] Furthermore, the initiator comprises one or more of dibenzoyl peroxide and azobisisobutyronitrile.

[0023] The present invention also provides a method for preparing an acid-free, high-temperature-resistant, high-adhesion pressure-sensitive tape, comprising the following steps: Step 1: Preparing polyacrylate: Add soft monomer, hard monomer, carboxyl functional monomer, amide functional monomer, hydroxyl functional monomer, and mixed solvent into a reactor and stir; purge the reactor with nitrogen protection, add initiator solution when the temperature in the reactor rises to 66-68°C, and keep the temperature for reaction for 1 hour to initiate the reaction and obtain reactive free radicals; then, add initiator solution every 0.5 hours and keep the temperature for reaction for 1.5 hours to allow for sufficient reaction; then add initiator solution again, raise the temperature to 80°C, keep the temperature for reaction for 3 hours, and after the reaction is completed, add diluent to dilute the material to obtain polyacrylate; Step 2: Apply a mixed solution of polyacrylate, curing agent, and tackifying resin to the PET substrate layer and dry it at 110°C for 3-5 minutes to obtain an adhesive layer. Finally, cover the surface of the adhesive layer with a release layer.

[0024] The present invention has the following beneficial effects: 1. The performance of the pressure-sensitive adhesive tape of the present invention reaches an initial tack (rolling ball method) of 13#, a peeling force of 1997 gf / 25mm (SUS steel plate), a 180° holding force (80°C, 30 days) of 0-1mm, a T-type 90° holding force (50°C, 30 days) of 5-6mm, an acid value close to zero, and is friendly to the adhered object and has long-lasting and durable adhesion.

[0025] 2. The pressure-sensitive adhesive tape of the present invention does not use toluene as a solvent, is harmless, environmentally friendly, and beneficial to human health.

[0026] 3. The polyacrylate synthesis process of the present invention is simpler and the operation is safer and more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Product structure diagram; In the figure: 1: PET substrate layer; 2: adhesive layer; 3: release layer DETAILED DESCRIPTION

[0028] The technical solution of the present invention is described clearly and completely below with reference to the accompanying drawings. It is apparent that the embodiments described are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0029] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] The raw materials used in the Examples and Comparative Examples are summarized in Table 1.

[0031] Table 1 Summary of raw materials Example 1 (1) Preparation of polyacrylate: 28 parts of n-BA, 7 parts of 2-EHA, 2.5 parts of AM, 0.08 parts of HEA, and 58 parts of (ETAC: MEK = 3:2) were mixed in a glass reactor and stirred to mix evenly. Nitrogen was continuously introduced to remove air, and the water bath was raised and heated to 66-68°C. Under a nitrogen atmosphere and a constant temperature of 66-68°C, 0.03 parts of AIBN were added to initiate monomer polymerization, and the reaction was continued for 1 hour. Every 0.5 hours, 0.01 parts of AIBN were added (three times in total) and the reaction was kept warm for 1.5 hours. 0.09 parts of AIBN were dissolved in 2.3 parts of VAC, and the mixture was then added to the reaction system. The temperature was naturally raised to about 80°C, and 0.09 parts of AIBN were added. The temperature was kept warm for 3 hours. After the reaction was completed, a diluent was added, and the diluent used was ethyl acetate, to obtain polyacrylate.

[0032] (2) Preparation of pressure-sensitive adhesive tape: a mixed solution of polyacrylate, curing agent and terpene phenol resin was prepared in a ratio of 100:0.4:10. The curing agent used was an isocyanate curing agent. The mixed solution was coated on the PET substrate layer and dried at 110°C for 3-5 minutes to obtain a 25 μm adhesive layer. Finally, a release layer was covered on the surface of the adhesive layer.

[0033] Example 2 (1) Preparation of polyacrylate: 14 parts of n-BA, 3.5 parts of 2-EHA, 1.25 parts of AM, 0.04 parts of HEA, and 40 parts of ETAC were mixed in a glass reactor, stirred and mixed evenly under nitrogen protection, and heated to 66-68°C. After one hour of constant temperature, 0.03 parts of AIBN were added to initiate monomer polymerization, and the polymerization reaction was carried out under the same temperature conditions for one hour; then 14 parts of n-BA, 3.5 parts of 2-EHA, 1.25 parts of AM, and 0.04 parts of HEA were mixed and slowly added to the reactor at a uniform speed through a peristaltic pump. At the same time, 0.01 parts of AIBN were added every 0.5 hours (three times in total), and the reaction was kept warm for 1.5 hours. 0.09 parts of AIBN were dissolved in 2.3 parts of VAC, and the mixture was added to the reaction system. The temperature was naturally raised to about 80°C, and 0.09 parts of AIBN were added. The temperature was kept warm for 3 hours. After the reaction was completed, a diluent was added, and the diluent used was ethyl acetate, to obtain polyacrylate.

[0034] (2) Preparation of pressure-sensitive adhesive tape: The coating scheme is the same as that in Example 1.

[0035] Example 3 (1) Preparation of polyacrylate: The synthesis method was the same as that in Example 2, except that the solvent ratio was changed to ETAC:MEK = 3:2.

[0036] (2) Preparation of pressure-sensitive adhesive tape: The coating scheme is the same as that in Example 1.

[0037] Example 4 (1) Preparation of polyacrylate: The synthesis method was the same as that in Example 2, except that the solvent ratio was changed to ETAC:MEK = 1:1.

[0038] (2) Preparation of pressure-sensitive adhesive tape: The coating scheme is the same as that in Example 1.

[0039] Example 5 (1) Preparation of polyacrylate: The synthesis method was the same as that in Example 2, except that the solvent ratio was changed to ETAC:MEK = 2:3.

[0040] Preparation of pressure-sensitive adhesive tape: The coating scheme is the same as that in Example 1.

[0041] Example 6 (1) Preparation of polyacrylate: The synthesis method is the same as that in Example 2, except that the solvent is changed to MEK.

[0042] (2) Preparation of pressure-sensitive adhesive tape: The coating scheme is the same as that in Example 1 Comparative Example 1 (1) Preparation of polyacrylate: The synthesis method was the same as that in Example 3, except that the solvent ratio was changed to ETAC:MEK = 1:1.

[0043] (2) Preparation of pressure-sensitive adhesive tape: The coating scheme is the same as that of Example 1, except that the tackifying resin is replaced by maleic rosin glycerol ester.

[0044] Comparative Example 2 (1) Preparation of polyacrylate: The synthesis method is the same as that in Example 3.

[0045] (2) Preparation of pressure-sensitive adhesive tape: The coating scheme is the same as that of Example 1, except that the tackifying resin is replaced by a polyol resin.

[0046] Comparative Example 3 (1) Preparation of polyacrylate: The synthesis method is the same as that in Example 1, except that AM is replaced by AA.

[0047] (2) Preparation of pressure-sensitive adhesive tape: The coating scheme is the same as that in Example 1.

[0048] Comparative Example 4 (1) Preparation of polyacrylate: The synthesis method is the same as that in Example 1, except that AM is replaced by AA:AM (1:1).

[0049] (2) Preparation of pressure-sensitive adhesive tape: The coating scheme is the same as that in Example 1.

[0050] Comparative Example 5 (1) Preparation of polyacrylate: 28 parts of n-BA, 7 parts of 2-EHA, 2.5 parts of AM, 0.08 parts of 2-HEA, 58 parts of (ETAC:MEK = 3:2), and an appropriate amount of AIBN were mixed in a glass reactor and stirred to mix evenly. Nitrogen was continuously introduced to remove air, and the water bath was raised and the temperature was raised to 66-68°C. The reaction was continued under a nitrogen atmosphere at a constant temperature of 66-68°C for 2 hours. The temperature was naturally raised to about 80°C and kept at this temperature for 3 hours. After the reaction was completed, a diluent was added, and the diluent used was ethyl acetate, to obtain polyacrylate.

[0051] (2) Preparation of pressure-sensitive adhesive tape: a mixed solution of polyacrylate, curing agent and terpene phenol resin was prepared in a ratio of 100:0.4:10. The curing agent used was an isocyanate curing agent. The mixed solution was coated on the PET substrate layer and dried at 110°C for 3-5 minutes to obtain a 25 μm adhesive layer. Finally, a release layer was covered on the surface of the adhesive layer.

[0052] Test example The performance of the adhesives and tapes provided in the above examples and comparative examples were tested, and the test standards were as follows: Viscosity: GB / T 21059-2007; Acid value: GB / T 4852-2002; Initial adhesion: GB / T 4852-2002; Thickness of adhesive layer: GB / T 7125-1999; 180° peel strength: GB / T 2792-1998; Adhesion: GB / T 4851-1998; The properties of the adhesives and tapes provided in the above embodiments and comparative examples were tested and the results are shown in Table 2.

[0053] Table 2 Test results of examples and comparative examples The present invention prepares Figure 1 In the pressure-sensitive adhesive tape shown, a PET substrate layer 1 and a release layer 3 are attached to both sides of the adhesive layer 2, respectively. A durability test was conducted on the adhesive tape Example 3, which had the best test results among the above embodiments. The test results are as follows: 180° adhesion (80°C, 30d): 0-1mm, 90° adhesion (50°C, 30d): 5-6mm.

[0054] According to Examples (1-6), there is no acid monomer in the synthetic monomers of the acrylate polymer, and a terpene phenol resin with an acid value close to 0 is used for coating. The test results show that the acid value of the tape is extremely low and negligible, thus avoiding corrosion when being attached; and acrylamide is added during the synthesis process, which increases the cohesive force of the adhesive itself, thereby enhancing the adhesive holding performance.

[0055] According to the comparative example (1-2), the tackifying resin was replaced. The results showed that the introduction of terpene phenol resin was more friendly to the object to be adhered and had a better effect.

[0056] In Comparative Examples 3-4, the acid value of the acrylic acid polymer is relatively high, which is not friendly to the adhered object and has poor adhesive performance. It is probably because the addition of acrylic acid reduces the cohesive force to a certain extent.

[0057] Compared with the complete one-pot method of Comparative Example 5, the methods of Examples 1-6 are safer and more reliable to operate.

[0058] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

[0059] The above specific implementation methods are detailed descriptions of the present invention. It cannot be considered that the specific implementation methods of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions and substitutions without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. An acid-free, high-temperature-resistant, high-adhesion pressure-sensitive tape, characterized in that: The adhesive layer comprises a PET substrate layer and a release layer attached to both sides thereof; the adhesive layer comprises the following raw material components by mass percentage: 80-90% polyacrylate; 0.3-0.4% curing agent; and 10-20% tackifying resin.

2. The acid-free, high-temperature-resistant, high-adhesion pressure-sensitive tape according to claim 1, characterized in that: The polyacrylate comprises the following components by weight: 30-40 parts of soft monomer, 2-5 parts of hard monomer, 0-5 parts of carboxyl functional monomer, 0-5 parts of amide functional monomer, 0.5-1 parts of hydroxyl functional monomer, 0.1-0.3 parts of initiator and 60-65 parts of mixed solvent.

3. The acid-free, high-temperature-resistant, high-adhesion pressure-sensitive tape according to claim 1, characterized in that: The curing agent is an isocyanate curing agent; the tackifying resin comprises one or more of α-terpene resin, β-terpene resin, and terpene phenolic resin.

4. The acid-free, high-temperature-resistant, high-adhesion pressure-sensitive tape according to claim 2, characterized in that: The soft monomer comprises one or more of n-butyl acrylate, ethyl acrylate and isooctyl acrylate.

5. The acid-free, high-temperature-resistant, high-adhesion pressure-sensitive tape according to claim 2, characterized in that: The hard monomer comprises one or more of methyl acrylate, vinyl acetate, and isobornyl.

6. The acid-free, high-temperature-resistant, high-adhesion pressure-sensitive tape according to claim 2, characterized in that: The carboxyl functional monomer includes one or more of acrylic acid, methacrylic acid, and butenedioic acid.

7. The acid-free, high-temperature-resistant, high-adhesion pressure-sensitive tape according to claim 2, characterized in that: The amide-containing functional monomers include one or more of acrylamide and methylbenzamide.

8. The acid-free, high-temperature-resistant, high-adhesion pressure-sensitive tape according to claim 2, characterized in that: The hydroxyl functional monomer includes one or more of hydroxypropyl acrylate, hydroxyethyl acrylate, and 4-hydroxybutyl acrylate.

9. The acid-free, high-temperature-resistant, high-adhesion pressure-sensitive tape according to claim 2, characterized in that: The solvent comprises one or more of ethyl acetate, butanone, and acetone; and the initiator comprises one or more of dibenzoyl peroxide and azobisisobutyronitrile.

10. A method for preparing an acid-free, high-temperature-resistant, high-adhesion pressure-sensitive tape according to any one of claims 1 to 9, characterized in that: The steps include: Step 1: Preparing polyacrylate: Add soft monomer, hard monomer, carboxyl functional monomer, amide functional monomer, hydroxyl functional monomer, and mixed solvent into a reactor and stir; purge the reactor with nitrogen protection, add initiator solution when the temperature in the reactor rises to 66-68°C, and keep the temperature for reaction for 1 hour to initiate the reaction and obtain reactive free radicals; then, add initiator solution every 0.5 hours and keep the temperature for reaction for 1.5 hours to allow for sufficient reaction; then add initiator solution again, raise the temperature to 80°C, keep the temperature for reaction for 3 hours, and after the reaction is completed, add diluent to dilute the material to obtain polyacrylate; Step 2: Apply a mixed solution of polyacrylate, curing agent, and tackifying resin to the PET substrate layer and dry it at 110°C for 3-5 minutes to obtain an adhesive layer. Finally, cover the surface of the adhesive layer with a release layer.

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