Adhesive for preventing stripping force from climbing and preparation method thereof

Abstract

The invention discloses an adhesive for preventing stripping force from climbing and a preparation method thereof, and relates to the technical field of adhesives, the adhesive comprises epoxy resin, a slow-release ultraviolet stabilizer, a cross-linking agent, a light stabilizer and an antioxidant; the slow-release ultraviolet stabilizer is of a core-shell structure with a double-layer shell wrapping an inner core, the double-layer shell structure comprises an inner-layer structure and an outer-layer structure, the inner-layer structure is a polydopamine material layer, and the outer-layer structure is a polyurethane layer; the inner core structure comprises an ultraviolet stabilizer and silane modified T O2, the silane modified T O2 is uniformly dispersed through surface modification, the photocatalytic activity of the silane modified T O2 is inhibited by a benzotriazole ultraviolet stabilizer, and oxidation of an adhesive layer can be reduced; benzotriazole is subjected to controlled release through a double-layer shell structure, ultraviolet rays are stably absorbed for a long time, adhesive layer embrittlement caused by excessive release in the initial stage is avoided, and the interface bonding stability is maintained; silane modified Ti O2 reflects ultraviolet rays, benzotriazole absorbs the ultraviolet rays, and light degradation of an adhesive layer is reduced under dual protection, so that the stripping force climbing rate of the adhesive is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and in particular to an adhesive capable of preventing peeling force from increasing and a preparation method thereof. Background Art

[0002] In electronic equipment manufacturing, such as FPC processes and lithium battery copper foil processes, the increase in the peel force of the protective film may make it difficult to completely tear off the protective film during subsequent processing or use, and may even leave residual glue stains on the surface of the copper foil, affecting product quality. It is important to choose the right adhesive and adherend.

[0003] In the existing technology, adhesives with high temperature resistance and low peeling performance are generally used. Through bridging and cross-linking by functional groups in the curing agent, the carboxyl and epoxy groups in the entire adhesive system can be stimulated to further deeply cross-link after being exposed to high temperatures. When the adhesive returns to room temperature, the peeling force not only does not increase, but also decreases slightly, making it easier to peel without leaving residual adhesive. However, this adhesive can only cope with situations after being exposed to high temperatures for a short period of time. When exposed to high temperatures for a long time, the deeply cross-linked structure in the adhesive is prone to failure, which will also cause a significant increase in the peeling force climbing rate. Summary of the Invention

[0004] The purpose of the present invention is to provide an adhesive that prevents peel force from increasing and a preparation method thereof, and to solve the following technical problems:

[0005] How to reduce the peel force increase rate of adhesives under long-term action.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] In a first aspect, the present invention discloses an adhesive for preventing peel force from climbing, comprising the following components in parts by weight: 60-70 parts of epoxy resin, 0.5-2 parts of a sustained-release UV stabilizer, 2-4 parts of a crosslinking agent, 1-3 parts of a light stabilizer, and 0.5-1 part of an antioxidant;

[0008] Preferably, the composition includes the following components in parts by weight: 65 parts of epoxy resin, 1 part of sustained-release ultraviolet stabilizer, 3 parts of cross-linking agent, 2 parts of light stabilizer, and 0.8 parts of antioxidant.

[0009] Furthermore, the sustained-release UV stabilizer is a core-shell structure with a double-shell covering an inner core, wherein the double-shell structure includes an inner layer structure and an outer layer structure, the inner layer structure is a polydopamine material layer, and the outer layer structure is a polyurethane layer; the inner core structure includes a UV stabilizer and silane-modified TiO2.

[0010] Furthermore, the preparation method of the sustained-release ultraviolet stabilizer comprises the following steps:

[0011] Step 1: Mixing a UV stabilizer and silane-modified TiO2 in a weight ratio of 1:1 to form a core agent, and adding the core agent to ethanol in a weight ratio of 1:1 and stirring evenly to obtain a suspension;

[0012] Preferably, the UV stabilizer is a benzotriazole UV stabilizer, such as UV-320, UV-P, UV-326, UV-327, etc.; more preferably UV-320;

[0013] Step 2: adding the suspension to a surfactant aqueous solution, adjusting the pH to 8.5, and then adding polydopamine in an amount twice that of the core agent, stirring at room temperature for 24 hours, collecting the solid after centrifugation and washing to obtain microparticles;

[0014] Preferably, the surfactant is sodium lauryl sulfate;

[0015] Step 3: dissolving the microparticles in deionized water, adding a polyurethane prepolymer in an amount three times that of the core agent, and then adding a catalyst, heating to 60°C for reaction for 4 hours, collecting the solid after centrifugation and freeze-drying to obtain a sustained-release UV stabilizer;

[0016] Preferably, the ratio of the microparticles to deionized water is 1 g:15 mL.

[0017] Furthermore, in step 1, the preparation method of the silane-modified TiO2 is as follows: nano-TiO2 and a silane coupling agent are mixed in a mass ratio of 5:1, then added to ethanol for ultrasonic dispersion for 1 hour, and then vacuum dried at 60°C for 6 hours to obtain silane-modified TiO2;

[0018] Preferably, the silane coupling agent is γ-aminopropyltriethoxysilane or γ-mercaptopropyltrimethoxysilane, preferably γ-aminopropyltriethoxysilane.

[0019] Furthermore, in step 2, the mass fraction of the surfactant aqueous solution is 0.5 wt%, and the volume ratio of the suspension to the surfactant aqueous solution is 1:1.

[0020] Furthermore, in step three, the catalyst is dibutyltin dilaurate, and the weight ratio of the catalyst to deionized water is (0.1-0.3):100, preferably 0.2:100.

[0021] Based on this, a preferred method for preparing a sustained-release ultraviolet stabilizer is obtained, comprising the following steps:

[0022] Step 1: UV-320 and silane-modified TiO2 are mixed in a weight ratio of 1:1 to form a core agent, and the core agent is added to ethanol in a weight ratio of 1:1 and stirred to obtain a suspension;

[0023] Step 2: adding the suspension to a 0.5 wt% sodium lauryl sulfate aqueous solution at a volume ratio of 1:1, adding 40% sodium hydroxide by mass to adjust the pH to 8.5, then adding polydopamine in an amount twice that of the core agent, stirring at room temperature for 24 hours, collecting the solid after centrifugation and washing to obtain microparticles;

[0024] Step 3: Dissolve the microparticles in deionized water at a ratio of 1 g:15 mL, add a polyurethane prepolymer that is 3 times the amount of the core agent, and then add dibutyltin dilaurate that is 0.002 times the amount of deionized water. Heat to 60°C and react for 4 hours. After centrifugation, collect the solid and freeze-dry it to obtain a sustained-release UV stabilizer.

[0025] Furthermore, the cross-linking agent is any one of polysuccinamide and polyglutaramide, or a combination of the two in any proportion;

[0026] Preferably, the cross-linking agent is a composition composed of polysuccinamide and polyglutaramide in a weight ratio of 1:1.

[0027] Furthermore, the light stabilizer is a hindered amine.

[0028] Furthermore, the antioxidant is a hindered phenol antioxidant or a phosphite antioxidant, or a combination of the two in any proportion;

[0029] Preferably, the hindered phenol antioxidants include antioxidant 1010, antioxidant 1076, antioxidant 264, and the like.

[0030] Preferably, the phosphite antioxidant includes antioxidant 168 and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate.

[0031] In a second aspect, the present invention further discloses a method for preparing an adhesive for preventing peel force from increasing, comprising the following steps:

[0032] The epoxy resin is dissolved in acetone in a weight ratio of 6:(1-1.5) and stirred until transparent, and then a slow-release UV stabilizer, a cross-linking agent, a light stabilizer and an antioxidant are added in sequence and stirred evenly to obtain an adhesive;

[0033] Preferably, the acetone is kept at a constant temperature of 50°C;

[0034] Preferably, each time a raw material is added, ultrasonic treatment is performed at 40 Hz for 5 minutes.

[0035] Based on this, a preferred method for preparing an adhesive that prevents peel force from increasing is obtained, comprising the following steps:

[0036] Prepare raw materials according to weight, including 65 parts of epoxy resin, 1 part of slow-release UV stabilizer, 3 parts of a composition composed of polysuccinamide and polyglutaramide in a weight ratio of 1:1, 2 parts of hindered amine, and 0.8 parts of antioxidant 1010: in a water bath maintained at a constant temperature of 50°C, dissolve the epoxy resin in acetone in a weight ratio of 6:1.2 and stir until transparent; then transfer the mixture to an ultrasonic mixer, and add the slow-release UV stabilizer, the composition composed of polysuccinamide and polyglutaramide in a weight ratio of 1:1, hindered amine, and antioxidant 1010 in sequence; after each raw material is added, ultrasonic treatment is performed at 40 Hz for 5 minutes to obtain an adhesive.

[0037] Beneficial effects of the present invention:

[0038] 1. The adhesive for preventing peel force increase of the present invention incorporates a sustained-release UV stabilizer. The adhesive has a core-shell structure with a double-shell covering an inner core. The double-shell structure comprises an inner layer and an outer layer. The inner layer comprises a polydopamine material layer. Dopamine undergoes oxidative self-polymerization under alkaline conditions and is adsorbed on the surface of the inner core through π-π interactions and hydrogen bonds, forming a dense coating. The outer layer comprises a polyurethane layer. During its formation, the polyurethane layer reacts with trace hydroxyl groups in water under the action of a catalyst to form a cross-linked polyurethane network that coats the inner layer surface, providing high-temperature mechanical stability.

[0039] 2. The core structure includes UV stabilizer and silane-modified TiO2. Silane-modified TiO2 is evenly dispersed through surface modification, and its photocatalytic activity is inhibited by benzotriazole UV stabilizers, which can reduce the oxidation of the adhesive layer; benzotriazole is controlled and released through a double-shell structure, absorbing UV rays stably for a long time, avoiding the embrittlement of the adhesive layer caused by excessive release in the early stage, and maintaining the stability of the interfacial bonding; silane-modified TiO2 reflects UV rays, and benzotriazole absorbs UV rays. The double protection reduces the photodegradation of the adhesive layer, thereby improving the peel force climbing rate of the adhesive. DETAILED DESCRIPTION

[0040] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0041] Unless otherwise specified, the experimental methods in the following examples are conventional methods and were performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials and reagents used in the following examples, unless otherwise specified, were all commercially available.

[0042] Preparation Example 1

[0043] Silane-modified TiO2 was prepared by following the following steps: nano-TiO2 and γ-aminopropyltriethoxysilane were mixed in an ultrasonic mixer at a weight ratio of 5:1 to form a mixture, and then ethanol twice the weight of the mixture was added, and the mixture was ultrasonically dispersed at 40 Hz for 1 hour, and then vacuum dried at 60°C for 6 hours to obtain silane-modified TiO2.

[0044] Preparation Example 2

[0045] The preparation of the sustained-release UV stabilizer is carried out in the following steps:

[0046] Step 1: UV-320 and the silane-modified TiO2 prepared in Preparation Example 1 were mixed in a weight ratio of 1:1 to form a core agent. The core agent and ethanol were added in a weight ratio of 1:1 to a stirred tank and stirred at 300 rpm for 30 minutes to obtain a suspension.

[0047] Step 2: adding the suspension to a 0.5 wt% sodium lauryl sulfate aqueous solution at a volume ratio of 1:1, adding 40% sodium hydroxide by mass to adjust the pH to 8.5, then adding polydopamine in an amount twice that of the core agent, stirring at 200 rpm at room temperature for 24 hours, collecting the solid after centrifugation, washing with deionized water, and drying to obtain microparticles;

[0048] Step 3: Dissolve the microparticles in deionized water at a ratio of 1 g:15 mL, add a polyurethane prepolymer that is 3 times the amount of the core agent, and then add dibutyltin dilaurate that is 0.002 times the amount of deionized water. Heat to 60°C and react for 4 hours. After centrifugation, collect the solid and freeze-dry it at -50°C for 24 hours to obtain a sustained-release UV stabilizer.

[0049] Comparative Preparation Example 1

[0050] The preparation of a sustained-release UV stabilizer is different from that of Preparation Example 2 in that the silane-modified TiO2 in Preparation Example 1 is replaced by nano-TiO2; the other steps and conditions remain the same, and a sustained-release UV stabilizer is finally prepared.

[0051] Comparative Preparation Example 2

[0052] The preparation of the sustained-release UV stabilizer is carried out in the following steps:

[0053] Step 1: UV-320 and the silane-modified TiO2 prepared in Preparation Example 1 were mixed in a weight ratio of 1:1 to form a core agent. The core agent and ethanol were added in a weight ratio of 1:1 to a stirred tank and stirred at 300 rpm for 30 minutes to obtain a suspension.

[0054] Step 2: The suspension was added to a 0.5 wt% sodium lauryl sulfate aqueous solution in a volume ratio of 1:1, 40% sodium hydroxide was added dropwise to adjust the pH to 8.5, and then polydopamine was added in an amount twice that of the core agent. The mixture was stirred at 200 rpm at room temperature for 24 h. The solid was collected after centrifugation and washed with deionized water. After drying, a sustained-release UV stabilizer was obtained.

[0055] Comparative Preparation Example 3

[0056] The UV stabilizer was prepared by sequentially following the following preparation steps: UV-320 was mixed with the silane-modified TiO2 of Preparation Example 1 in a weight ratio of 1:1 to obtain the UV stabilizer.

[0057] Example 1

[0058] Prepare adhesive:

[0059] Prepare 60 parts of epoxy resin, 0.5 parts of the sustained-release UV stabilizer of Preparation Example 2, 2 parts of a composition composed of polysuccinamide and polyglutaramide in a weight ratio of 1:1, 1 part of hindered amine, and 0.5 parts of antioxidant 1010 according to parts by weight: In a water bath maintained at a constant temperature of 50°C, the epoxy resin was dissolved in acetone in a weight ratio of 6:1.2 and stirred until transparent. The mixture was then transferred to an ultrasonic mixer, and the sustained-release UV stabilizer, the composition composed of polysuccinamide and polyglutaramide in a weight ratio of 1:1, the hindered amine, and the antioxidant 1010 were added in sequence. After each raw material was added, the mixture was ultrasonically treated at 40 Hz for 5 minutes to obtain an adhesive.

[0060] Example 2

[0061] Prepare adhesive:

[0062] Prepare 65 parts of epoxy resin, 1 part of the sustained-release UV stabilizer of Preparation Example 2, 3 parts of a composition composed of polysuccinamide and polyglutaramide in a weight ratio of 1:1, 2 parts of hindered amine, and 0.8 parts of antioxidant 1010 according to weight parts: In a water bath maintained at a constant temperature of 50°C, the epoxy resin was dissolved in acetone in a weight ratio of 6:1.2 and stirred until transparent. The mixture was then transferred to an ultrasonic mixer, and the sustained-release UV stabilizer, the composition composed of polysuccinamide and polyglutaramide in a weight ratio of 1:1, the hindered amine, and the antioxidant 1010 were added in sequence. After each raw material was added, the mixture was ultrasonically treated at 40 Hz for 5 minutes to obtain an adhesive.

[0063] Example 3

[0064] Prepare adhesive:

[0065] Prepare 70 parts of epoxy resin, 2 parts of the sustained-release UV stabilizer of Preparation Example 2, 4 parts of a composition composed of polysuccinamide and polyglutaramide in a weight ratio of 1:1, 3 parts of hindered amine, and 1 part of antioxidant 1010 according to parts by weight: In a water bath maintained at a constant temperature of 50°C, the epoxy resin was dissolved in acetone in a weight ratio of 6:1.2 and stirred until transparent. The mixture was then transferred to an ultrasonic mixer, and the sustained-release UV stabilizer, the composition composed of polysuccinamide and polyglutaramide in a weight ratio of 1:1, the hindered amine, and the antioxidant 1010 were added in sequence. After each raw material was added, the mixture was ultrasonically treated at 40 Hz for 5 minutes to obtain an adhesive.

[0066] Example 4

[0067] Prepare adhesive:

[0068] Prepare 65 parts of epoxy resin, 1 part of the sustained-release UV stabilizer of Preparation Example 2, 3 parts of polysuccinamide, 2 parts of hindered amine, and 0.8 parts of antioxidant 1076 according to parts by weight: In a water bath maintained at a constant temperature of 50°C, the epoxy resin is dissolved in acetone in a weight ratio of 6:1.2 and stirred until transparent. Then, the mixture is transferred to an ultrasonic mixer, and the sustained-release UV stabilizer, polysuccinamide, hindered amine, and antioxidant 1076 are added in sequence. After each raw material is added, the mixture is ultrasonically treated at 40 Hz for 5 minutes to obtain an adhesive.

[0069] Example 5

[0070] Prepare adhesive:

[0071] Prepare 65 parts of epoxy resin, 1 part of the sustained-release UV stabilizer of Preparation Example 2, 3 parts of polyglutaramide, 2 parts of hindered amine, and 1680.8 parts of antioxidant in parts by weight: In a water bath maintained at a constant temperature of 50°C, dissolve the epoxy resin in acetone in a weight ratio of 6:1.2 and stir until transparent. Then, transfer the mixture to an ultrasonic mixer, and add the sustained-release UV stabilizer, polyglutaramide, hindered amine, and antioxidant 168 in sequence. After each addition of the raw materials, ultrasonic treatment is performed at 40 Hz for 5 minutes to obtain an adhesive.

[0072] Comparative Example 1

[0073] The adhesive was prepared in the same manner as in Example 1, except that the sustained-release UV stabilizer of Preparation Example 2 was replaced by the sustained-release UV stabilizer of Preparation Example 1. The other steps and conditions remained the same, and the adhesive was finally prepared.

[0074] Comparative Example 2

[0075] The adhesive was prepared. Compared with Example 1, the only difference was that the sustained-release UV stabilizer of Preparation Example 2 was replaced by the sustained-release UV stabilizer of Preparation Example 2, and the other steps and conditions remained the same to finally prepare the adhesive.

[0076] Comparative Example 3

[0077] The adhesive was prepared in the same manner as in Example 1, except that the sustained-release UV stabilizer of Preparation Example 2 was replaced by the sustained-release UV stabilizer of Preparation Example 3. The other steps and conditions remained the same, and the adhesive was finally prepared.

[0078] Comparative Example 4

[0079] The adhesive was prepared in the same manner as in Example 1, except that the sustained-release UV stabilizer in Preparation Example 2 was replaced with UV-320. The other steps and conditions remained the same, and the adhesive was finally prepared.

[0080] The adhesives prepared in Examples 1-5 and Comparative Examples 1-4 were coated on films to prepare protective films. The preparation method was as follows: a biaxially oriented polyester film with a thickness of 25 μm was selected as the substrate, the film surface was cleaned with ethanol and air-dried, and then the adhesive was evenly coated on the film surface by a doctor blade coating method. The wet film thickness was controlled to be 30 μm. Then, a wavelength of 365 nm and an energy density of 500 mJ / cm 2 The film was irradiated with a mercury lamp for 30 seconds, and finally transferred to an oven and cured at 120°C for 30 minutes under nitrogen protection to obtain a protective film coated with an adhesive.

[0081] The protective films made of the adhesives of Examples 1-5 and Comparative Examples 1-4 were subjected to performance tests, including transparency tests and peel strength tests, using the following test methods:

[0082] Transparency test: Refer to GB / T 2410-2008 to test light transmittance;

[0083] Peel force test: Refer to ASTM D903, including initial peel force test and peel force climbing rate test after aging at 80℃ for 72h.

[0084] The test results are listed in Table 1, which is as follows:

[0085] Table 1

[0086]

[0087] By analyzing the data in Table 1, it can be seen that compared with Comparative Examples 1-4, the protective films made of the adhesives of Examples 1-5 have slightly higher light transmittance, lower initial peel rate, and significantly lower peel force increase rate after aging for 72 hours at 80°C. This shows that the adhesive of the present invention has a stronger effect of resisting peel force increase.

[0088] The above is a detailed description of an embodiment of the present invention. However, the content described is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. An adhesive for preventing peeling force from increasing, characterized in that: The composition comprises the following components in parts by weight: 60-70 parts of epoxy resin, 0.5-2 parts of sustained-release ultraviolet stabilizer, 2-4 parts of cross-linking agent, 1-3 parts of light stabilizer and 0.5-1 part of antioxidant.

2. The adhesive for preventing peel force from increasing according to claim 1, wherein: The sustained-release UV stabilizer is a core-shell structure with a double-shell covering an inner core, wherein the double-shell structure includes an inner layer structure and an outer layer structure, the inner layer structure is a polydopamine material layer, and the outer layer structure is a polyurethane layer; the inner core structure includes a UV stabilizer and silane-modified TiO2.

3. The adhesive for preventing peel force from increasing according to claim 2, wherein: The preparation method of the sustained-release ultraviolet stabilizer comprises the following steps: Step 1: Mixing a UV stabilizer and silane-modified TiO2 in a weight ratio of 1:1 to form a core agent, and adding the core agent to ethanol in a weight ratio of 1:1 and stirring evenly to obtain a suspension; Step 2: adding the suspension to a surfactant aqueous solution, adjusting the pH to 8.5, and then adding polydopamine in an amount twice that of the core agent, stirring at room temperature for 24 hours, collecting the solid after centrifugation and washing to obtain microparticles; Step 3: Dissolve the microparticles in deionized water, add a polyurethane prepolymer that is 3 times the amount of the core agent, then add a catalyst, heat to 60°C and react for 4 hours, collect the solid after centrifugation and freeze-dry to obtain a slow-release UV stabilizer.

4. The adhesive for preventing peel force from increasing according to claim 3, wherein: In step 1, the preparation method of the silane-modified TiO2 is as follows: nano-TiO2 and a silane coupling agent are mixed in a mass ratio of 5:1, then added to ethanol for ultrasonic dispersion for 1 hour, and then vacuum-dried at 60°C for 6 hours to obtain silane-modified TiO2.

5. The adhesive for preventing peel force from increasing according to claim 3, wherein: In step 2, the mass fraction of the surfactant aqueous solution is 0.5 wt %, and the volume ratio of the suspension to the surfactant aqueous solution is 1:

1.

6. The adhesive for preventing peel force from increasing according to claim 3, wherein: In step three, the catalyst is dibutyltin dilaurate, and the weight ratio of the catalyst to deionized water is (0.1-0.3):

100.

7. The adhesive for preventing peel force from increasing according to claim 1, wherein: The cross-linking agent is any one of polysuccinamide and polyglutaramide, or a combination of the two in any proportion.

8. The adhesive for preventing peel force from increasing according to claim 1, wherein: The light stabilizer is a hindered amine.

9. The adhesive for preventing peel force from increasing according to claim 1, wherein: The antioxidant is one of a hindered phenol antioxidant and a phosphite antioxidant, or a combination of the two in any proportion.

10. A method for preparing an adhesive for preventing peel force from increasing according to any one of claims 1 to 9, characterized in that: The steps include: The epoxy resin is dissolved in acetone in a weight ratio of 6:(1-1.5) and stirred until transparent, and then a slow-release ultraviolet stabilizer, a cross-linking agent, a light stabilizer and an antioxidant are added in sequence and stirred evenly to obtain an adhesive.

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