Pressure-sensitive hot melt adhesive for flexible electronic packaging and application thereof
By optimizing the composition and dosage of pressure-sensitive hot melt adhesive, the problems of insufficient insulation performance of flexible electronic devices in low-temperature bending resistance and high-temperature and high-humidity environments have been solved, achieving high flexibility and long-term resistance to damp heat, and significantly extending the service life of flexible electronic devices.
Patent Information
- Application Number
- CN202511750310.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-26
- Publication Date
- 2026-01-23
AI Technical Summary
Traditional hot melt adhesives for flexible electronic packaging are insufficient in terms of low-temperature bending resistance and insulation performance under high temperature and high humidity conditions, and cannot meet the requirements of flexible electronic devices.
By optimizing the selection and addition amount of components in pressure-sensitive hot melt adhesives, especially by controlling the mass ratio of elastomer mixtures, tackifying resins and softeners, and by introducing a combination of natural rubber, SIS and SBS, along with dicumyl peroxide crosslinking agent, the flexibility, adhesion and insulation properties of the adhesive are improved, and its resistance to damp heat is enhanced.
The pressure-sensitive hot melt adhesive provided can withstand more than 5,000 bends at -20℃, with an insulation resistance as high as 1.1×10¹²Ω. It can be used stably for more than 350 days in an environment of 40℃ and 90% humidity, significantly improving the service life of flexible electronic devices.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of pressure-sensitive hot melt adhesive for flexible electronic packaging, in particular to a pressure-sensitive hot melt adhesive for flexible electronic packaging and application thereof. BACKGROUND
[0002] With the development of science and technology, electronic devices are evolving towards lightness, flexibility and wearability. As a key support, flexible electronic technology has given birth to revolutionary products such as foldable mobile phones, wearable health monitoring devices, electronic skin, flexible display screens and flexible solar cells. However, traditional rigid packaging materials (such as epoxy resin) cannot meet the requirements of these new flexible devices, so higher requirements are put forward for hot melt adhesive. Flexible electronics need to withstand bending, folding, stretching and even twisting, which requires the packaging adhesive layer to have excellent flexibility and excellent electrical insulation to prevent short circuits. However, the existing hot melt adhesives for flexible electronic packaging generally have poor low-temperature bending resistance (less than 3000 times at -20℃), and the insulation performance decreases significantly in high-temperature and high-humidity environments (insulation resistance is less than 1x10 11 Ω after 1000h). SUMMARY
[0003] In order to solve the above problems, the present application provides a pressure-sensitive hot melt adhesive for flexible electronic packaging. By optimizing the selection and addition amount of each raw material in the system, the product provided has excellent bonding performance, low-temperature bending resistance, wide temperature stability, high insulation safety and long-term moisture resistance, which meets the application requirements of flexible electronic packaging.
[0004] In one aspect, the present application provides a pressure-sensitive hot melt adhesive for flexible electronic packaging, comprising at least the following components by weight: 25-35 parts of an elastomer mixture, 35-65 parts of tackifying resin, 10-25 parts of softening agent, 0.1-1.2 parts of antioxidant, and 0.2-1.5 parts of crosslinking agent; the elastomer mixture comprises at least natural rubber, SIS and SBS.
[0005] In one embodiment, the mass ratio of the elastomer mixture, tackifying resin and softening agent is (2.5-3.5):(4.5-5):(1.4-2.3).
[0006] By comprehensively controlling the addition amount of the elastomer mixture, tackifying resin and softening agent in the system, and especially controlling the mass ratio of the elastomer mixture, tackifying resin and softening agent to be (2.5-3.5):(4.5-5):(1.4-2.3), the initial tack of the product provided can reach 8.5-10.2 N / cm, and the flexible electronic substrate can be quickly and stably bonded.
[0007] In an embodiment, the mass ratio of the natural rubber, SIS (styrene-isoprene-styrene triblock copolymer), SBS (styrene-butadiene-styrene triblock copolymer) is (7.5-10.5):(12.5-17.5):(5-7).
[0008] In an embodiment, the initial value of the Wallace plasticity (Po) of the natural rubber is >35, and the plasticity retention index (PRI) (P30 / PO) x 100 is >60. In an embodiment, the natural rubber is of the model SVR-3L and is from Yunnan Natural Rubber Industry Co., Ltd.
[0009] In an embodiment, the SIS has a styrene content of 15 wt%, a melt index (GB / T3682-2000) of 25 g / 10min, is of the model 1140, and is from Shandong Polysaint Technology Co., Ltd.
[0010] In an embodiment, the SBS has a styrene / butadiene mass ratio (S / B) of 4:6, a melt index (GB / T3682-2000) of 0.1-5.0 g / 10min, is of the model YH-792, and is from Balin Petrochemical.
[0011] The present application introduces an elastomer mixture composed of natural rubber, SIS, and SBS, further controls the mass ratio (7.5-10.5):(12.5-17.5):(5-7), endows the pressure-sensitive hot melt adhesive for flexible electronic packaging with excellent flexibility, improves the initial tack of the product, increases the modulus and hardness of the adhesive, balances the "too soft" problem caused by the natural rubber and SIS, and better meets the actual application requirements.
[0012] In an embodiment, the tackifying resin at least includes hydrogenated rosin ester and terpene resin.
[0013] In an embodiment, the mass ratio of the hydrogenated rosin ester and the terpene resin is (22.5-26):(22-25).
[0014] Further, the present application introduces a tackifying resin combination including hydrogenated rosin ester and terpene resin, which has good compatibility with the elastomer mixture in the system, further controls the addition amount, endows the product with excellent initial tack and holding power, and also helps to prevent yellowing and performance decay of the adhesive after long-term use.
[0015] In an embodiment, the softening agent is at least one selected from naphthenic oil, polyisobutylene oil, or poly-alpha-olefin oil.
[0016] Further, the application reduces the melt viscosity by introducing a softening agent into the system, improves the processability and increases the flexibility of the product, especially the introduction of naphthenic oil, which has good compatibility with SIS, SBS and natural rubber in the system, avoids low temperature crystallization precipitation, causes the problems of colloidal turbidity or low temperature flexibility decrease and the like.
[0017] In one embodiment, the antioxidant comprises at least a hindered phenolic antioxidant.
[0018] In one embodiment, the hindered phenolic antioxidant is selected from at least one of antioxidant 1010, antioxidant 1076 or antioxidant 1135.
[0019] The product provided by the application introduces a hindered phenolic antioxidant, especially antioxidant 1010, so that the adhesion strength retention rate of the product provided by the application is still above 90% after being placed in a high and low temperature environment of-40℃ to 85℃ for 1000h, avoiding obvious aging and yellowing of the colloidal, and the performance is stable and reliable.
[0020] In one embodiment, the crosslinking agent is selected from a peroxide crosslinking agent.
[0021] In one embodiment, the peroxide crosslinking agent comprises at least dicumyl peroxide.
[0022] In one embodiment, the addition amount of the crosslinking agent is 1.94-4.38% of the total mass of the elastomer mixture.
[0023] Based on the elastomer mixture in the system, by using dicumyl peroxide as the crosslinking agent, the addition amount of the crosslinking agent in the system is controlled to be 1.94-4.38% of the total mass of the elastomer mixture, the crosslinking degree is controlled to be 25-30%, and the product is endowed with excellent low temperature flexibility, which can withstand more than 5000 times of ±180° cyclic bending at-20℃, and meets the use scene of repeated deformation of flexible electronics.
[0024] The pressure-sensitive hot melt adhesive for flexible electronic packaging provided by the application has an insulation resistance of 1.1x10 12 Ω or more, which can effectively protect electronic components from short circuit risk, and can be stably used for more than 350 days in a 40℃, 90% humidity environment, significantly prolonging the service life of the flexible electronic product.
[0025] Another aspect of the application provides a preparation method of a pressure-sensitive hot melt adhesive for flexible electronic packaging, at least comprising the following steps: melt mixing an elastomer mixture with tackifying resin and softening agent to obtain a mixture, adding an antioxidant and a crosslinking agent to the mixture for crosslinking treatment to obtain a crosslinked material, extruding the crosslinked material, cooling and shaping, and cutting.
[0026] In an embodiment, the method for preparing the elastomer mixture comprises the following steps: adding natural rubber, SIS and SBS into a mixer, controlling the temperature at 140-150 DEG C, the rotating speed at 300-500 rpm, and mixing for 20-30 min to obtain the elastomer mixture.
[0027] In an embodiment, the melting mixing comprises the following steps: adding the elastomer mixture into a double screw extruder, heating to 140-150 DEG C, adding tackifying resin and softening agent, keeping the rotating speed at 400-500 rpm, and melting mixing for 0.5-1 h.
[0028] In an embodiment, the cross-linking treatment is performed at a temperature of 120-150 DEG C for 20-30 min.
[0029] The third aspect of the present application provides a pressure-sensitive hot melt adhesive for flexible electronic packaging.
[0030] In an embodiment, the method for using the pressure-sensitive hot melt adhesive for flexible electronic packaging comprises the following steps: melting the hot melt adhesive particles at 150-160 DEG C, uniformly coating the surface of the flexible electronic substrate by using a dispenser, controlling the coating amount at 30-40 g / m2, and completing the packaging by keeping the pressure at 0.4-0.5 MPa for 10-12 s after adhering the packaging layer.
[0031] Advantages 1. The present application provides a pressure-sensitive hot melt adhesive for flexible electronic packaging, which has excellent bonding performance, low-temperature bending resistance, wide temperature stability, high insulation safety and long-term moisture resistance by optimizing the selection and addition amount of each raw material in the system.
[0032] 2. The present application controls the addition amount of the elastomer mixture, tackifying resin and softening agent in the system, and especially controls the mass ratio of the elastomer mixture, tackifying resin and softening agent at (2.5-3.5):(4.5-5):(1.4-2.3), so that the initial tack of the product can reach 8.5-10.2 N / cm, and the flexible electronic substrate can be quickly and stably bonded.
[0033] 3. The present application introduces the elastomer mixture composed of natural rubber, SIS and SBS, further controls the mass ratio of the elastomer mixture at (7.5-10.5):(12.5-17.5):(5-7), and improves the initial tack of the product, increases the modulus and hardness of the adhesive, balances the "too soft" problem caused by natural rubber and SIS, and better meets the actual application requirements.
[0034] 4、The application is good in compatibility with the elastomer mixture in the system by introducing the tackifying resin combination comprising hydrogenated rosin ester and terpene resin, further controls the addition amount, gives the product excellent initial tack and holding power, and also helps to prevent yellowing and performance attenuation of the adhesive after long-term use.
[0035] 5、The product provided by the application introduces hindered phenolic antioxidant, especially antioxidant 1010, so that the adhesion strength retention rate of the product is still above 90% after being placed in high and low temperature environment of-40℃ to 85℃ for 1000h, avoiding obvious aging and yellowing of the adhesive, and stable and reliable performance.
[0036] 6、Based on the elastomer mixture in the system, by using dicumyl peroxide as a crosslinking agent, the addition amount of the crosslinking agent in the system is further controlled to be 1.94-4.38% of the total mass of the elastomer mixture, the crosslinking degree is controlled to be 25-30%, and the product is given excellent low temperature flexibility, which can withstand more than 5000 times of ±180° cyclic bending at-20℃ environment, meeting the use scene of repeated deformation of flexible electronics.
[0037] 7、The pressure-sensitive hot melt adhesive for flexible electronic packaging provided by the application has insulation resistance of 1.1*10^12Ω or more, which can effectively protect electronic components from short circuit risk, and can be stably used for more than 350 days in a 40℃, 90% humidity environment, significantly prolonging the service life of flexible electronic products. DETAILED DESCRIPTION
[0038] The information of each raw material in the examples and comparative examples of the application is shown in Table 1.
[0039] Table 1
[0040] Examples 1-7, Comparative Examples 1-11 The examples 1-7 and comparative examples 1-11 of the application provide, on the one hand, a pressure-sensitive hot melt adhesive for flexible electronic packaging, the formula is shown in Table 2 and Table 3.
[0041] Table 2
[0042] Table 3
[0043] Embodiments 1-7 and Comparative Examples 1-11 of the present application provide, in another aspect, a method for preparing a pressure-sensitive hot melt adhesive for flexible electronic packaging, comprising the following steps: melt-mixing an elastomer mixture with tackifying resin and softener to obtain a mixture, adding an antioxidant and a crosslinking agent to the mixture to perform crosslinking treatment to obtain a crosslinked material, extruding the crosslinked material, cooling and shaping, and cutting.
[0044] The method for preparing the elastomer mixture comprises the following steps: adding natural rubber, SIS, and SBS into an internal mixer, controlling the temperature to be 150°C and the rotation speed to be 300 rpm, and mixing for 30 min to obtain the elastomer mixture.
[0045] The melt-mixing comprises the following steps: adding the elastomer mixture into a twin-screw extruder, heating to 150°C, adding the tackifying resin and the softener, maintaining the rotation speed to be 400 rpm, and melt-mixing for 1 h.
[0046] The crosslinking treatment is performed at a temperature of 120°C for 30 min.
[0047] Performance test 1. Adhesion strength test: According to the ASTM D3359 standard, the hot melt adhesives provided by each of the embodiments and the comparative examples were melt-coated between a polyimide film and a copper foil, and after curing, a universal testing machine was used to perform 180° peeling test at a test speed of 50 mm / min, and the peeling strength (N / cm) was recorded. The results are shown in Table 4.
[0048] 2. The hot melt adhesives provided by each of the embodiments and the comparative examples were melted at 160°C, uniformly coated on the surface of a flexible electronic substrate (polyimide film) by a dispensing machine, the coating amount was controlled to be 35 g / m², and after being attached and packaged, the pressure was maintained at 0.5 MPa for 10 s to complete the packaging, to obtain a flexible electronic sample, which was subjected to tests (1)-(4). The results are shown in Table 4.
[0049] (1) Bending resistance test: The packaged flexible electronic sample was fixed on a bending tester, the bending angle was set to ±180°, the bending frequency was 1 time / s, and the sample was subjected to cyclic bending at -20°C. The number of bending times when the adhesive layer cracked or peeled off was recorded.
[0050] (2) High and low temperature resistance test: The packaged flexible electronic sample was placed in a -40°C low temperature chamber and an 85°C high temperature chamber for 1000 h, respectively, and then taken out and restored to room temperature (25°C). The adhesion strength retention rate (test value / initial value x 100%) was tested.
[0051] (3) Insulation performance test: The insulating resistance (Ω) of the encapsulated flexible electronic sample is determined by using an insulating resistance meter under a test voltage of 100 V.
[0052] (4) Humidity resistance test: The encapsulated flexible electronic sample is placed in a constant temperature and humidity chamber at 40 DEG C and 90% relative humidity, and the time (days) when bubbles or peeling occurs in the adhesive layer is observed and recorded.
[0053] Table 4
[0054] As can be seen from Table 4, the pressure-sensitive hot melt adhesive for flexible electronic encapsulation provided in Examples 1-7 has obviously improved comprehensive performance compared with Comparative Examples 1-11.
Claims
1. A pressure sensitive hot melt adhesive for flexible electronic packaging, characterized in that, At least comprising the following components by weight parts: an elastomer mixture 25-35 parts, tackifying resin 35-65 parts, softener 10-25 parts, antioxidant 0.1-1.2 parts, crosslinking agent 0.2-1.5 parts; the elastomer mixture at least comprising natural rubber, SIS, SBS.
2. The pressure sensitive hot melt adhesive for flexible electronic packaging according to claim 1, wherein The mass ratio of the elastomer mixture, tackifying resin, softener is (2.5-3.5):(4.5-5):(1.4-2.3).
3. The pressure sensitive hot melt adhesive for flexible electronics packaging according to claim 1, wherein, The mass ratio of the natural rubber, SIS, SBS is (7.5-10.5):(12.5-17.5):(5-7).
4. The pressure sensitive hot melt adhesive for flexible electronics packaging according to claim 1, wherein, The tackifying resin at least comprises hydrogenated rosin ester and terpene resin.
5. The pressure sensitive hot melt adhesive for flexible electronics packaging according to claim 4, wherein, The mass ratio of the hydrogenated rosin ester and terpene resin is (22.5-26):(22-25).
6. The pressure sensitive hot melt adhesive for flexible electronics packaging according to claim 1, wherein, The softener is at least one selected from naphthenic oil, polyisobutylene oil or poly-alpha-olefin oil.
7. The pressure sensitive hot melt adhesive for flexible electronics packaging according to claim 1, wherein The antioxidant at least comprises hindered phenolic antioxidant.
8. The pressure sensitive hot melt adhesive for flexible electronics packaging according to claim 1, wherein, The crosslinking agent is selected from peroxide crosslinking agent.
9. The pressure sensitive hot melt adhesive for flexible electronic encapsulation according to any one of claims 1 to 8, characterized in that, The preparation method at least comprises the following steps: melt mixing the elastomer mixture with the tackifying resin and the softener to obtain a mixture, adding the antioxidant and the crosslinking agent to the mixture to perform crosslinking treatment to obtain a crosslinked material, extruding the crosslinked material, cooling and shaping, and cutting.
10. Use of a pressure sensitive hot melt adhesive according to any of claims 1 to 8 for flexible electronic packaging, characterized in that, Applied to flexible electronic packaging.