High-viscosity acrylate pressure-sensitive adhesive and production method thereof

Abstract

The invention relates to the technical field of adhesives, and discloses a high-viscosity acrylate pressure-sensitive adhesive and a production method thereof.The high-viscosity acrylate pressure-sensitive adhesive is formed by mixing an acrylic resin emulsion serving as a bonding substance with auxiliary materials such as a dispersing agent and a defoaming agent, and a first modified monomer and a second modified monomer are added in the preparation process of the acrylic resin emulsion, so that the high-viscosity acrylate pressure-sensitive adhesive is obtained. Molecular chains of acrylic ester are designed, a large number of functional groups are introduced into a main chain and a side chain of the acrylic ester at the same time, mutual crosslinking between the molecular chains is achieved, and the functional groups such as silicon-oxygen bonds, ether bonds, hydroxyl and rigid rings in the structures of the first modified monomer and the second modified monomer are utilized; the prepared acrylate pressure-sensitive adhesive has excellent bonding strength and high temperature resistance.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, specifically to a high-viscosity acrylic pressure-sensitive adhesive and its production method. Background Technology

[0002] Pressure-sensitive adhesives (PSAs) are materials that adhere to a substrate under pressure and possess a certain degree of durable bonding performance. Acrylic PSAs are widely used in labels, tapes, medical patches, and electronic packaging due to their excellent weather resistance, transparency, oxidation resistance, and controllable bonding properties. However, with the continued application of acrylic PSAs, their shortcomings have gradually become apparent. For example, in automotive tapes, conventional acrylic PSAs, due to insufficient bonding strength and poor high-temperature resistance, can delaminate under long-term vibration and temperature changes, leading to the scattering of automotive components and affecting driving safety. Therefore, developing acrylic PSAs with good high-temperature resistance and excellent bonding performance is of great significance for their further development in the automotive industry.

[0003] Since acrylic resins are formed by the free radical polymerization of acrylate monomers, the design of the molecular chain of acrylic resins to prepare acrylic pressure-sensitive adhesives with excellent comprehensive performance has become a research hotspot. Summary of the Invention

[0004] In order to solve the problems mentioned in the background art, the purpose of this invention is to provide a high-viscosity acrylic pressure-sensitive adhesive and its production method.

[0005] The objective of this invention can be achieved through the following technical solutions: A high-viscosity acrylic pressure-sensitive adhesive, comprising the following raw materials by weight: Acrylic resin emulsion 60-80 parts, dispersant 40-50 parts, defoamer 1-1.5 parts, wetting agent 0.5-1 part, curing agent 2-4 parts; The preparation method of the acrylic resin emulsion includes the following steps: Step A: Add the emulsifier sodium dodecylbenzenesulfonate to the ethanol aqueous solution and stir to mix evenly. Then add the soft monomer, hard monomer, functional monomer, modified monomer one, modified monomer two and initiator azobisisobutyronitrile. After the addition is complete, turn on the stirrer to form a mixture. Step B: Place the mixture in a polymerization reactor, introduce nitrogen gas, raise the temperature to 80-82℃, maintain the temperature for polymerization for 4-6 hours, then stop heating, cool down and discharge the material, adjust the pH to 7-8, and the acrylic resin emulsion can be obtained.

[0006] As a further embodiment of the present invention, the dispersant is at least one of ethyl acetate, acetone or toluene; the defoamer is BYK-A555; the wetting agent is BY-9401 or BY-9338; and the curing agent is an isocyanate curing agent.

[0007] As a further aspect of the present invention, in step A, the soft monomer is butyl acrylate or isooctyl acrylate; the hard monomer is methyl methacrylate or butyl methacrylate; and the functional monomer is hydroxyethyl acrylate.

[0008] As a further aspect of the present invention, in step A, the method for preparing the modified monomer is as follows: Polytetrahydrofuran and 1,4-dioxane were added to a reaction vessel and stirred until homogeneous. Then, [(dicycloheptenyl)ethyl]dimethylchlorosilane and an acid-binding agent were added to the mixture. After the addition was complete, the temperature was raised to 60-65℃ and kept at that temperature for 3-6 hours. The solvent was then evaporated and the product was collected to obtain modified monomer one.

[0009] As a further embodiment of the present invention, the molar ratio of the polytetrahydrofuran and [(dicycloheptenyl)ethyl]dimethylchlorosilane is 1:1-2.

[0010] As a further embodiment of the present invention, the acid-binding agent is pyridine or triethylamine.

[0011] In the above technical solution, the hydroxyl substituent in the polytetrahydrofuran structure can undergo a substitution reaction with the silicon chloride in the [(dicycloheptenyl)ethyl]dimethylchlorosilane structure under the action of an acid-binding agent to obtain modified monomer one.

[0012] As a further aspect of the present invention, the preparation method of the modified monomer II includes the following steps: Step ①: Add 1,3-diepoxyglycerol ether, glycerol, isocyanate methyl methacrylate, and anhydrous toluene to the reactor, start stirring, and after a homogeneous reaction solution is formed, continue to add catalyst to the reactor. After the addition is complete, raise the temperature to 70-80℃, keep it at the temperature and stir for 4-8 hours to obtain the chain-extended modified product. Step ②: Add the chain extender, 2-benzylsuccinic acid, and N,N-dimethylformamide to the polymerization reactor, purge with nitrogen for protection, start stirring, and mix evenly. Then, raise the temperature to 60-70℃ and keep it at that temperature for 1-2 hours. Next, add the phase transfer catalyst to the polymerization reactor and raise the temperature to 90-100℃. Continue stirring for 8-16 hours, then stop heating, cool down, and discharge the material to obtain modified monomer II.

[0013] As a further aspect of the present invention, in step ①, the catalyst is any one of dioctyltin dilaurate, dibutyltin dilaurate, methyl thiotin, or octyl thiotin.

[0014] As a further aspect of the present invention, in step ②, the phase transfer catalyst is any one of tetramethylammonium bromide, tetrabutylammonium bromide, tetrabutylammonium bisulfate, or tetramethylammonium chloride.

[0015] In the above technical solution, 1,3-diepoxyglycerol ether glycerol and isocyanate ethyl methacrylate are first used as raw materials. Under the action of a catalyst, the active hydroxyl groups in their structures can undergo an amino esterification reaction with the isocyanate groups to obtain a chain-extended modified body containing two equivalent epoxy substituents and one equivalent unsaturated alkenyl substituent. Under the action of a phase transfer catalyst, the two equivalent epoxy substituents in its structure can undergo a continuous ring-opening esterification reaction with the two equivalent carboxyl substituents in the 2-benzylsuccinic acid structure to obtain a polymeric monomer with ester bond linkage and alternating structure, namely modified monomer II.

[0016] A method for producing a high-viscosity acrylic pressure-sensitive adhesive includes the following steps: Step 1: Weigh and prepare all the raw materials according to their weight proportions; The second step is to add the acrylic resin emulsion to the dispersant and stir until homogeneous. Then, add the wetting agent, curing agent, and defoamer. Stir and mix at 200-300 rpm for 10-30 minutes at room temperature, and let stand to defoam.

[0017] The beneficial effects of this invention are: The modified monomer prepared in this invention is a polytetrahydrofuran derivative. The large number of ether bonds in its structure can form hydrogen bonds with the adhered objects, thus exposing more hydrogen bond adhesion sites in the prepared pressure-sensitive adhesive, effectively enhancing the adhesive performance of the pressure-sensitive adhesive. In addition, the modified monomer also contains rigid rings and silicon-oxygen bonds in its structure, which can improve the stability of the acrylate molecular chain, thereby enhancing the high-temperature resistance of the pressure-sensitive adhesive.

[0018] The modified monomer die structure prepared by this invention contains a large number of unsaturated alkenyl functional groups, which can act as crosslinking agents during the polymerization process, so that the formed acrylic resin molecular chains have a three-dimensional crosslinked network structure. The presence of this crosslinked network structure makes the movement of acrylate molecular chains more difficult, thereby improving the high temperature resistance of the pressure-sensitive adhesive. In addition, the large number of ether bonds and hydroxyl groups generated by the ring-opening reaction in its structure can effectively enhance the adhesion performance of the pressure-sensitive adhesive, while the rigid benzene ring in the structure can also enhance the high temperature stability of the pressure-sensitive adhesive.

[0019] This invention designs the molecular chain of acrylate, introducing a large number of functional groups into its main chain and side chains simultaneously, and achieves cross-linking between molecular chains to prepare an acrylate pressure-sensitive adhesive with excellent bonding strength and high temperature resistance.

[0020] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is an infrared analysis test image of modified monomer one. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0024] Example 1 A high-viscosity acrylic pressure-sensitive adhesive, comprising the following raw materials by weight: 60 parts acrylic resin emulsion, 40 parts ethyl acetate dispersant, 1 part defoamer BYK-A555, 0.5 parts wetting agent BY-9401, and 2 parts terephthalic diisocyanate curing agent; The preparation method of the pressure-sensitive adhesive includes the following steps: Step 1: Weigh and prepare all the raw materials according to their weight proportions; The second step is to add the acrylic resin emulsion to the dispersant ethyl acetate and stir until homogeneous. Then, add the wetting agent BY-9401, the curing agent terephthalic acid diisocyanate, and the defoamer BYK-A555. Stir and mix at 200 rpm for 30 minutes at room temperature, and let stand to defoam.

[0025] The preparation method of the acrylic resin emulsion includes the following steps: Step A: Add 1.2g of sodium dodecylbenzenesulfonate emulsifier to a 70% (v / v) ethanol aqueous solution, stir and mix evenly, then add 35g of butyl acrylate, 4g of methyl methacrylate, 2g of hydroxyethyl acrylate, 1.5g of modified monomer one, 0.3g of modified monomer two and 0.2g of initiator azobisisobutyronitrile. After the addition is complete, start stirring to form a mixture. Step B: Place the mixture in a polymerization reactor, introduce nitrogen gas, raise the temperature to 80°C, maintain the temperature for 6 hours, stop heating, cool down and discharge the material, adjust the pH to 7, and the acrylic resin emulsion can be obtained.

[0026] The preparation method of modified monomer one is as follows: 0.6 g of polytetrahydrofuran with a number average molecular weight of 1000 and 1,4-dioxane were added to a reaction vessel and stirred until homogeneous. Then, 0.13 g of [(dicycloheptenyl)ethyl]dimethylchlorosilane and 0.1 g of triethylamine were added to the mixture. After the addition was complete, the temperature was raised to 65°C and kept at that temperature for 4 hours. The solvent was then evaporated and the product was collected to obtain modified monomer one.

[0027] Figure 1 This is the infrared analysis test image of the modified monomer 1, where 3338 cm⁻¹ -1 The characteristic absorption peak appearing at 3067 cm⁻¹ is the characteristic absorption peak of hydroxyl groups. -1 The characteristic absorption peak appearing at 2800 cm⁻¹ is the characteristic absorption peak of CH in unsaturated C=C, and is located at 2800 cm⁻¹. -1 ~3000cm -1 The characteristic absorption peak appearing at 1074 cm⁻¹ is the characteristic absorption peak of saturated CH₄. -1 The characteristic absorption peak appearing at this point is the characteristic absorption peak of Si-O produced by the substitution reaction.

[0028] The preparation method of modified monomer II includes the following steps: Step ①: Add 0.2g of 1,3-diepoxyglycerol ether glycerol, 0.15g of isocyanate methacrylate and anhydrous toluene to the reaction vessel, start stirring, and after a uniform reaction solution is formed, continue to add 0.01g of dibutyltin dilaurate to the reaction vessel. After the addition is complete, raise the temperature to 75℃, keep it warm and stir for 6 hours to obtain the chain-extended modified body; Step ②: Add 0.5g of chain extender, 0.3g of 2-benzylsuccinic acid and N,N-dimethylformamide to the polymerization reactor, purge with nitrogen for protection, start stirring, and mix evenly. Then raise the temperature to 65℃ and keep it at that temperature for 2 hours. Next, add 0.1g of tetrabutylammonium bromide to the polymerization reactor and raise the temperature to 95℃. Continue stirring for 12 hours, then stop heating, cool down and discharge the material to obtain modified monomer II.

[0029] 0.1 g of modified monomer II was weighed as a titration test sample and titrated using the soap back titration method. The results showed that the ester group content in the sample was 8.171 mmol / g. It is speculated that the ester group was formed by the ring-opening esterification reaction between the epoxy substituent in the chain-extended modified structure and the carboxyl substituent in the 2-benzylsuccinic acid structure.

[0030] Example 2 A high-viscosity acrylic pressure-sensitive adhesive, comprising the following raw materials by weight: 75 parts acrylic resin emulsion, 45 parts ethyl acetate dispersant, 1.5 parts defoamer BYK-A555, 0.8 parts wetting agent BY-9338, and 3 parts terephthalic acid diisocyanate curing agent; The preparation method of the pressure-sensitive adhesive includes the following steps: Step 1: Weigh and prepare all the raw materials according to their weight proportions; The second step is to add the acrylic resin emulsion to the dispersant ethyl acetate and stir until homogeneous. Then, add the wetting agent BY-9338, the curing agent terephthalic acid diisocyanate, and the defoamer BYK-A555. Stir and mix at 200 rpm for 20 minutes at room temperature, and let stand to defoam.

[0031] The preparation method of the acrylic resin emulsion is the same as that in Example 1.

[0032] Example 3 A high-viscosity acrylic pressure-sensitive adhesive, comprising the following raw materials by weight: 80 parts acrylic resin emulsion, 50 parts ethyl acetate dispersant, 1.5 parts defoamer BYK-A555, 1 part wetting agent BY-9338, and 4 parts terephthalic acid diisocyanate curing agent; The preparation method of the pressure-sensitive adhesive includes the following steps: Step 1: Weigh and prepare all the raw materials according to their weight proportions; The second step is to add the acrylic resin emulsion to the dispersant ethyl acetate and stir until homogeneous. Then, add the wetting agent BY-9338, the curing agent terephthalic acid diisocyanate, and the defoamer BYK-A555. Stir and mix at 300 rpm for 10 minutes at room temperature, and let stand to defoam.

[0033] The preparation method of the acrylic resin emulsion is the same as that in Example 1.

[0034] Comparative Example 1 A high-viscosity acrylic pressure-sensitive adhesive, comprising the following raw materials by weight: 75 parts acrylic resin emulsion, 45 parts ethyl acetate dispersant, 1.5 parts defoamer BYK-A555, 0.8 parts wetting agent BY-9338, and 3 parts terephthalic acid diisocyanate curing agent; The preparation method of the pressure-sensitive adhesive includes the following steps: Step 1: Weigh and prepare all the raw materials according to their weight proportions; The second step is to add the acrylic resin emulsion to the dispersant ethyl acetate and stir until homogeneous. Then, add the wetting agent BY-9338, the curing agent terephthalic acid diisocyanate, and the defoamer BYK-A555. Stir and mix at 200 rpm for 20 minutes at room temperature, and let stand to defoam.

[0035] The preparation method of the acrylic resin emulsion differs from that in Example 1 in that no modified monomer is added, but all other aspects are the same.

[0036] Comparative Example 2 A high-viscosity acrylic pressure-sensitive adhesive, comprising the following raw materials by weight: 75 parts acrylic resin emulsion, 45 parts ethyl acetate dispersant, 1.5 parts defoamer BYK-A555, 0.8 parts wetting agent BY-9338, and 3 parts terephthalic acid diisocyanate curing agent; The preparation method of the pressure-sensitive adhesive includes the following steps: Step 1: Weigh and prepare all the raw materials according to their weight proportions; The second step is to add the acrylic resin emulsion to the dispersant ethyl acetate and stir until homogeneous. Then, add the wetting agent BY-9338, the curing agent terephthalic acid diisocyanate, and the defoamer BYK-A555. Stir and mix at 200 rpm for 20 minutes at room temperature, and let stand to defoam.

[0037] The preparation method of the acrylic resin emulsion differs from that in Example 1 in that no modified monomer II is added, while the rest are the same.

[0038] Comparative Example 3 A high-viscosity acrylic pressure-sensitive adhesive, comprising the following raw materials by weight: 75 parts acrylic resin emulsion, 45 parts ethyl acetate dispersant, 1.5 parts defoamer BYK-A555, 0.8 parts wetting agent BY-9338, and 3 parts terephthalic acid diisocyanate curing agent; The preparation method of the pressure-sensitive adhesive includes the following steps: Step 1: Weigh and prepare all the raw materials according to their weight proportions; The second step is to add the acrylic resin emulsion to the dispersant ethyl acetate and stir until homogeneous. Then, add the wetting agent BY-9338, the curing agent terephthalic acid diisocyanate, and the defoamer BYK-A555. Stir and mix at 200 rpm for 20 minutes at room temperature, and let stand to defoam.

[0039] The preparation method of the acrylic resin emulsion differs from that in Example 1 in that modified monomer one and modified monomer two are not added, while the rest are the same.

[0040] Performance testing The pressure-sensitive adhesive used in the examples and comparative examples was uniformly coated onto the surface of the PI film, with the coating amount controlled at 3 g / cm³. 2 After coating, the sample was placed in an 80℃ oven for curing. After complete curing, it was removed, and a release film was applied to the coated surface. The sample was then placed in a 60℃ oven for 16 hours for curing. This sample was then used as a test sample for a 180° peel strength test. The specific test method referred to standard GB / T 2792-2014. After the test, the test samples from the same batch were placed in a 150℃ oven for 48 hours. The surface phenomena of the adhesive film were observed to evaluate the high-temperature resistance of the pressure-sensitive adhesive. The results are recorded in the table below: Table 1 - Test Results Analysis of the test results shows that the pressure-sensitive adhesives prepared in the embodiments of the present invention exhibited excellent bonding performance and high-temperature resistance. After removing modified monomer one or modified monomer two from the acrylic resin emulsion, the properties of the prepared pressure-sensitive adhesives decreased significantly. It can be concluded that the addition of modified monomer one and modified monomer two plays an important role in the bonding performance and high-temperature resistance of the pressure-sensitive adhesives.

[0041] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of these embodiments are merely to aid in understanding the method and core ideas of the present invention, including the best mode, and to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to those expressed in the claims, or if they include equivalent structural elements that are not substantially different from those expressed in the claims, then these other embodiments should also be included within the scope of the claims.

[0042] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-viscosity acrylic pressure-sensitive adhesive, characterized in that, By weight, it includes the following ingredients: Acrylic resin emulsion 60-80 parts, dispersant 40-50 parts, defoamer 1-1.5 parts, wetting agent 0.5-1 part, curing agent 2-4 parts; The preparation method of the acrylic resin emulsion includes the following steps: Step A: Add the emulsifier sodium dodecylbenzenesulfonate to the ethanol aqueous solution and stir to mix evenly. Then add the soft monomer, hard monomer, functional monomer, modified monomer one, modified monomer two and initiator azobisisobutyronitrile. After the addition is complete, turn on the stirrer to form a mixture. Step B: Place the mixture in a polymerization reactor, introduce nitrogen gas, raise the temperature to 80-82℃, maintain the temperature for polymerization for 4-6 hours, then stop heating, cool down and discharge the material, adjust the pH to 7-8, and the acrylic resin emulsion can be obtained.

2. The high-viscosity acrylic pressure-sensitive adhesive according to claim 1, characterized in that, The dispersant is at least one of ethyl acetate, acetone, or toluene; the defoamer is BYK-A555; the wetting agent is BY-9401 or BY-9338; and the curing agent is an isocyanate curing agent.

3. The high-viscosity acrylic pressure-sensitive adhesive according to claim 1, characterized in that, In step A, the soft monomer is butyl acrylate or isooctyl acrylate; the hard monomer is methyl methacrylate or butyl methacrylate; and the functional monomer is hydroxyethyl acrylate.

4. The high-viscosity acrylic pressure-sensitive adhesive according to claim 1, characterized in that, In step A, the modified monomer is prepared by reacting polytetrahydrofuran and [(dicycloheptenyl)ethyl]dimethylchlorosilane as raw materials under the action of an acid-binding agent.

5. The high-viscosity acrylic pressure-sensitive adhesive according to claim 4, characterized in that, The molar ratio of the polytetrahydrofuran to [(dicycloheptenyl)ethyl]dimethylchlorosilane is 1:1-2.

6. The high-viscosity acrylic pressure-sensitive adhesive according to claim 4, characterized in that, The acid-binding agent is pyridine or triethylamine.

7. The high-viscosity acrylic pressure-sensitive adhesive according to claim 1, characterized in that, The preparation method of the modified monomer II includes the following steps: Step ①: Using 1,3-diepoxyglycerol ether glycerol and isocyanate methyl methacrylate as raw materials, a reaction is carried out under the action of a catalyst to obtain the chain-extended modified product; Step ②: Under the action of a phase transfer catalyst, 2-benzylsuccinic acid and the chain extender undergo a continuous ring-opening esterification reaction to obtain modified monomer II.

8. The high-viscosity acrylic pressure-sensitive adhesive according to claim 7, characterized in that, In step ①, the catalyst is any one of dioctyltin dilaurate, dibutyltin dilaurate, methyl tin mercaptan, or octyltin mercaptan.

9. The high-viscosity acrylic pressure-sensitive adhesive according to claim 7, characterized in that, In step ②, the phase transfer catalyst is any one of tetramethylammonium bromide, tetrabutylammonium bromide, tetrabutylammonium bisulfate, or tetramethylammonium chloride.

10. A method for producing a high-viscosity acrylic pressure-sensitive adhesive as described in claim 1, characterized in that, Includes the following steps: Step 1: Weigh and prepare all the raw materials according to their weight proportions; The second step is to add the acrylic resin emulsion to the dispersant and stir until homogeneous. Then, add the wetting agent, curing agent, and defoamer. Stir and mix at 200-300 rpm for 10-30 minutes at room temperature, and let stand to defoam.

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