Preparation method of non-reactive hot melt adhesive

Abstract

The invention discloses a preparation method of a non-reactive hot melt adhesive, and relates to the technical field of hot melt adhesives, and the preparation method comprises the following steps: constructing a three-dimensional network structure by adopting maleic anhydride grafted branched SIS / SBS, and matching with a compounded system of hydrogenated C9 petroleum resin and terpene-phenol resin, so that the dissolution rate of an electrolyte is less than or equal to 1.0%, the peel strength is greater than or equal to 25N / 25mm, and the shear strength is greater than or equal to 4.0 MPa; a gradient heating and dynamic vulcanization combined process is developed, partial crosslinking of a branched polymer is realized in conventional equipment at 170-190 DEG C, the initial viscosity is improved by 30%, the melt viscosity is less than or equal to 80,000 mPa.s, the product can be subjected to dispensing construction through a dispensing machine, and meanwhile, hot melting and solvent dissolution can be carried out to be perfectly compatible with existing coating production line construction to form a hot melting adhesive tape. The adhesive property retention rate of the hot melt adhesive in a wide temperature range from-40 DEG C to 85 DEG C is greater than 90%, the hot melt adhesive can be widely applied to scenes such as power battery cell fixation, tab packaging and 5G electronic component adhesion, and the product reliability and the production efficiency are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of hot melt adhesives, and specifically relates to a preparation method of a non-reactive hot melt adhesive. Background Art

[0002] With the development of lithium-ion batteries, lithium batteries are widely used in various small digital products due to their high energy density and excellent adaptability to high and low temperature environments. The aluminum-plastic film bonded with hot melt adhesive is a key material for soft-pack lithium-ion batteries, and in order to protect the battery from damage, a layer of aluminum-plastic film needs to be encapsulated on the outside of the soft-pack lithium-ion battery. Now, soft-pack lithium batteries have many advantages such as being thin, light, having a high energy density, and good safety, and are a type of battery with a wide range of application fields.

[0003] Currently, the method used to prepare hot melt adhesives is to mix raw materials and formulations in a certain proportion during the production and manufacturing process, then add the raw materials, etc. into a reaction kettle, heat it to make it melt, and stir to make it evenly mixed. The temperature of the reaction kettle is determined according to the different softening points of the raw materials.

[0004] The soft packaging of the lithium battery requires the stacking of a hot melt adhesive film. After wrapping around the outside of the battery for one week, it is connected by bonding at the joint. The power battery requires hot melt adhesive for bonding and fixing. Both require the hot melt adhesive used for fixing and bonding to have good bonding effect, and at the same time, it is necessary to meet the characteristics of resistance to electrolyte, acid and alkali corrosion, so as to reduce the energy loss of the battery. However, the hot melt adhesive film in the prior art is prone to edge lifting after long-term use, indicating that the bonding is not firm enough, which affects the safety and efficiency of the lithium battery during use. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a preparation method of a non-reactive hot melt adhesive, which solves the problems raised in the above background art.

[0006] To achieve the above purposes, the present invention is realized through the following technical solutions: A preparation method of a non-reactive hot melt adhesive, comprising:

[0007] Mixing polyolefin elastomer POE, random polyolefin APAO, elastomer polymer SEBS and / or SIS, and maleic anhydride grafted polyolefin resin with tackifying resin and antioxidant respectively, heating to 170°C - 200°C and stirring for 1 - 2 hours, and cooling to obtain the non-reactive hot melt adhesive;

[0008] The tackifying resin comprises a combination of hydrogenated C9 petroleum resin and terpene phenol resin, and the elastomer polymer comprises maleic anhydride grafted branched SIS / SBS, wherein SIS is styrene-isoprene-styrene block copolymer, and SBS is styrene-butadiene-styrene block copolymer.

[0009] Furthermore, the maleic anhydride-grafted branched SIS / SBS is prepared by the following method:

[0010] Dissolve SIS or SBS in toluene, add maleic anhydride monomer and initiator, react at 80 - 100 °C for 4 - 6 hours to form a grafted polymer, and then introduce polybutadiene branches with a molecular weight of 5k - 20k through anionic polymerization to form a three-dimensional network structure, with a grafting rate of 0.8% - 2.0%.

[0011] Furthermore, the softening point of the hydrogenated C9 petroleum resin is 100 - 145 °C, the residual double bond rate is < 5%, and the mass ratio with the terpene phenol resin is 2:1; the softening point of the terpene phenol resin is 90 - 120 °C, and it contains phenolic hydroxyl polar groups.

[0012] Furthermore, the compounding composition of the tackifying resin is: 40 - 60 parts of hydrogenated C9 petroleum resin, 20 - 30 parts of terpene phenol resin, and 0 - 5 parts of epoxidized polybutadiene liquid rubber.

[0013] Furthermore, the preparation method further includes the following steps:

[0014] Add 0.1 - 0.5% of peroxide vulcanizing agent for dynamic vulcanization treatment in the later stage of melt mixing, and adopt a gradient temperature rising method during the mixing process: segmental temperature control at 150 °C → 170 °C → 190 °C.

[0015] Furthermore, the hot melt adhesive further contains functional additives: 0.5 - 1.5 parts of silane coupling agent KH-550, 1 - 3 parts of nano-silica, or 0 - 2 parts of montmorillonite hybrid filler, and the montmorillonite is modified by KH-550.

[0016] Furthermore, the melt index of the POE is 2 - 50 g / 10 min, the melt viscosity of the APAO at 190 °C is 1.2 - 12 mPa·s, and the styrene content of the SEBS and / or SIS is 15% - 30%.

[0017] Furthermore, the grafting rate of the maleic anhydride-grafted modified polyolefin resin is 0.5% - 2.0%, the addition amount is 5 - 15 parts, and at least 5 parts of epoxidized polybutadiene liquid rubber are included in the tackifying resin.

[0018] Furthermore, the hot melt adhesive meets the following performance indicators:

[0019] The peel strength ≥ 25 N / 25 mm, the shear strength ≥ 4.0 MPa, the electrolyte elution rate ≤ 1.0%, and the adhesion performance retention rate after high and low temperature cycling (-40 °C to 85 °C) > 90%.

[0020] Further, the hot melt adhesive further comprises a hydrogenated dendritic random polymer, which is a branched polystyrene-conjugated diene block copolymer with a bimodal molecular weight distribution and a number average molecular weight of 80,000-250,000.

[0021] The present invention provides a preparation method of a non-reactive hot melt adhesive. Compared with the prior art, it has the following beneficial effects:

[0022] 1. Through the synergistic effect of the branched SIS / SBS three-dimensional network and the hydrogenated resin, the electrolyte dissolution rate is reduced to ≤1.0% (a 60% decrease compared to the traditional system), and at the same time, the peel strength is increased to ≥25 N / 25 mm and the shear strength is ≥4.0 MPa, breaking through the industry bottleneck of electrolyte corrosion and interface failure of power batteries and meeting the application requirements in the wide temperature range of -40°C to 85°C.

[0023] 2. The melt viscosity of the branched polymer (≤80,000 mPa·s at 170°C) is perfectly matched with the existing dispensing machine equipment, and there is no need to transform the production line; the dynamic vulcanization technology simplifies the process flow, the initial tack is increased by more than 30%, and the production efficiency is increased by 25%, achieving a balance between high performance and low cost manufacturing.

[0024] 3. A three-dimensional network structure is constructed by using maleic anhydride-grafted branched SIS / SBS, and a compounding system of hydrogenated C9 petroleum resin and terpene phenol resin is used to make the electrolyte dissolution rate ≤1.0%, the peel strength ≥25 N / 25 mm, and the shear strength ≥4.0 MPa; a combined process of gradient heating and dynamic vulcanization is developed to achieve partial cross-linking of the branched polymer in a conventional equipment at 170-190°C, ensuring that while the initial tack is increased by 30%, the melt viscosity ≤80,000 mPa·s. This product can be applied by a dispensing machine, and at the same time, it can be perfectly compatible with hot melting and solvent dissolution for construction on the existing coating production line to make a hot melt tape. The adhesive performance retention rate of this hot melt adhesive is >90% in the wide temperature range of -40°C to 85°C, and it can be widely used in scenarios such as power battery cell fixing, tab encapsulation, and bonding of 5G electronic components, significantly improving product reliability and production efficiency. Specific embodiments

[0025] Next, the technical solutions of the present invention will be described in detail through specific examples, but it should be clearly stated that these examples are for illustrative purposes only and are not construed as limiting the scope of the present invention.

[0026] Example 1

[0027] Preparation of a high electrolyte-resistant hot melt adhesive

[0028] ①. Formulation composition:

[0029] Polyolefin elastomer POE (melt index 20 g / 10 min): 40 parts

[0030] Atactic polyolefin APAO (viscosity at 190 °C: 8 mPa·s): 15 parts

[0031] Branched SIS (grafting ratio: 1.5%, branched chain molecular weight: 10k): 15 parts

[0032] Hydrogenated C9 petroleum resin (softening point: 140 °C, residual double bond rate: 3%): 50 parts

[0033] Terpene phenol resin (softening point: 110 °C): 25 parts

[0034] Silane coupling agent KH-550: 1.0 part

[0035] Nano-silica (modified with KH-550, particle size: 20 nm): 2 parts

[0036] Antioxidant BHT: 0.3 part

[0037] ②. Preparation process:

[0038] 1. Pretreatment stage:

[0039] Mix the hydrogenated C9 petroleum resin and terpene phenol resin in a mass ratio of 2:1, and melt and stir at 150 °C for 30 minutes;

[0040] Pre-mix the branched SIS and maleic anhydride grafted polyolefin (grafting ratio: 1.5%) in a ratio of 10:1.

[0041] 2. Melting and mixing of main materials:

[0042] Add POE, APAO, and pre-mixed branched SIS to the reaction kettle, and stir at 170 °C at 60 rpm for 30 minutes;

[0043] Add the pre-melted resin mixture and antioxidant, and maintain vacuum degassing at 170 °C (pressure ≤ 0.1 MPa) for 1 hour.

[0044] 3. Dispersion of functional additives:

[0045] Cool down to 180 °C, add the silane coupling agent and nano-silica, and disperse at high speed shear of 1000 rpm for 20 minutes;

[0046] Cool to room temperature, slice and package.

[0047] ③. Performance testing:

[0048] Peeling strength (aluminum): 26.5 N / 25 mm

[0049] Shearing strength (PC / aluminum): 4.2 MPa

[0050] Dissolution rate of electrolyte (1M LiPF6 / EC:DEC = 1:1): 0.8%

[0051] High and low temperature cycle (-40°C / 85°C, 100 times): Adhesion strength retention rate 92%

[0052] Example 2

[0053] Preparation of high shear strength type hot melt adhesive

[0054] ①. Composition:

[0055] POE (melt index 300 g / 10 min): 35 parts

[0056] APAO (viscosity at 190°C 5 mPa·s): 20 parts

[0057] Branched SBS (grafting rate 1.8%, branched chain molecular weight 15k): 18 parts

[0058] Hydrogenated C9 petroleum resin (softening point 135°C): 45 parts

[0059] Terpene phenol resin (softening point 100°C): 20 parts

[0060] Epoxidized polybutadiene liquid rubber (epoxy value 0.4): 5 parts

[0061] Montmorillonite hybrid filler (modified with KH-550, layer spacing 3.8 nm): 1.5 parts Antioxidant 1010: 0.4 part

[0062] ②. Preparation process:

[0063] Pretreatment stage:

[0064] When the tackifying resin is mixed, add epoxidized polybutadiene liquid rubber and pre-melt at 160°C for 1 hour; pre-mix branched SBS with 0.3 part of peroxide DCP.

[0065] Dynamic vulcanization process:

[0066] When the main materials are mixed to 180°C, add 0.2 part of DCP in three times, with an interval of 10 minutes each time; maintain stirring at 180°C for 40 minutes to complete partial crosslinking.

[0067] Filler dispersion:

[0068] Add montmorillonite hybrid filler and stir at 800 rpm for 30 minutes to ensure the exfoliation of the layered structure. ③. Performance test:

[0069] Peel strength (aluminum): 24.8 N / 25 mm

[0070] Shear strength (steel / aluminum): 2.5 MPa

[0071] Electrolyte dissolution rate: 0.9%

[0072] Creep resistance (85°C / 24h): Deformation ≤ 0.3%.

[0073] Example 3

[0074] Preparation of Ultra-Low Dissolution Rate Hot Melt Adhesive

[0075] ①. Composition:

[0076] POE (Melt index 20 g / 10 min): 45 parts

[0077] Hydrogenated dendritic random polymer (Mn = 150,000, bimodal distribution): 10 parts

[0078] Branched SIS (Grafting rate 2.0%, branch molecular weight 20k): 12 parts

[0079] Hydrogenated C9 petroleum resin (Softening point 145°C, double bond residue rate 2%): 60 parts

[0080] Terpene phenol resin (Softening point 95°C): 30 parts

[0081] Nano-silica (Aerosol method, particle size 15nm): 3 parts

[0082] Antioxidant 168: 0.5 part

[0083] ②. Preparation process:

[0084] Gradient temperature rise mixing:

[0085] Initial temperature 150°C, add POE and hydrogenated dendritic polymer and stir for 20 minutes;

[0086] Raise the temperature to 170°C, add the mixture of branched SIS and tackifying resin, and stir for 40 minutes;

[0087] Finally raise the temperature to 190°C and vacuum degas for 30 minutes.

[0088] Supercritical fluid assisted dispersion:

[0089] Before adding nano-silica, introduce CO2 supercritical fluid (pressure 15 MPa, temperature 40°C) and process for 10 minutes to promote filler dispersion.

[0090] ③. Performance test:

[0091] Peel strength (anodic aluminum oxide): 28.2 N / 25 mm

[0092] Shear strength (aluminum / aluminum): 4.7 MPa

[0093] Electrolyte dissolution rate: 0.6%

[0094] Thermal stability (TGA, 5% weight loss temperature): 325°C

[0095] Performance verification

[0096] I. Experimental materials and equipment

[0097]

[0098] II. Experimental methods and test standards

[0099]

[0100]

[0101] III. Experimental design and data recording

[0102] 1. Peel strength test

[0103] Specimen preparation: Apply hot melt adhesive on the surface of aluminum (thickness 0.2 mm, width 25 mm), bond it with another piece of aluminum, press at 170 °C for 10 s, and cure at room temperature for 24 h.

[0104] Data recording:

[0105]

[0106] 2. Shear strength test

[0107] Specimen preparation: Aluminum-aluminum lap joint (100×25×1 mm), adhesive application area 25×12.5 mm, press at 170 °C for 10 s, and cure at room temperature for 24 h.

[0108] Data recording:

[0109]

[0110]

[0111] 3. Electrolyte dissolution rate test

[0112] Specimen preparation: Make a 5 g sample block of hot melt adhesive, soak it in 1 M LiPF6 solution at 70 °C for 72 h.

[0113] Data recording:

[0114]

[0115] 4. High-temperature shear retention rate test

[0116] Specimen preparation: Aluminum-aluminum lap joint (same as shear strength test), apply a constant load of 1.5 MPa at 85 °C.

[0117] Data recording:

[0118]

[0119]

[0120] 5. Low-temperature flexibility test

[0121] Specimen preparation: Coat the hot melt adhesive on the aluminum surface (thickness 0.5 mm), freeze at -40 °C for 2 h, and then fold it at 180°.

[0122] Data recording:

[0123]

[0124] 6. Tack test

[0125] Specimen preparation: Coat the hot melt adhesive on the PET film (thickness 0.1 mm), and test the tack of the rolling ball at room temperature.

[0126] Data recording:

[0127]

[0128]

[0129] 7. Holding tack test

[0130] Specimen preparation: Bond the hot melt adhesive to the stainless steel plate (25×25 mm), and hang a 500 g weight at 25 °C.

[0131] Data recording:

[0132]

[0133] IV. Experimental conclusions

[0134] 1. Comprehensive performance advantages: Examples 1, 2, and 3 are significantly superior to commercially available samples A and B in all 7 tests, especially in terms of the electrolyte dissolution rate (≤0.9% vs. ≥1.8%) and the high-temperature shear retention rate (≥320 min vs. ≤150 min).

[0135] 2. Structure-property relationship:

[0136] The synergistic effect of the branched polymer and the hydrogenated resin significantly improves the electrolyte resistance and cohesive strength;

[0137] The dynamic vulcanization process and the nano-fillers enhance the interfacial bonding force and anti-creep performance.

[0138] 3. Application value: The products of the examples meet the stringent requirements for hot melt adhesives in fields such as power batteries and electronic packaging, and have the potential for industrial promotion.

Claims

1. A preparation method of a non-reactive hot melt adhesive, characterized in that, Comprising: Mix polyolefin elastomer (POE), atactic polyolefin (APAO), elastomeric polymer (SEBS) and / or SIS, and maleic anhydride grafted modified polyolefin resin with tackifying resin and antioxidant respectively, heat to 170°C - 200°C and stir for 1 - 2 hours, and obtain the non-reactive hot melt adhesive after cooling. The tackifying resin comprises a combination of hydrogenated C9 petroleum resin and terpene phenol resin, and the elastomeric polymer comprises maleic anhydride grafted branched SIS / SBS.

2. The preparation method of a non-reactive hot melt adhesive according to claim 1, characterized in that, The maleic anhydride grafted branched SIS / SBS is prepared by the following method: Dissolve SIS or SBS in toluene, add maleic anhydride monomer and initiator, react at 80 - 100°C for 4 - 6 hours to generate grafted polymer, and then introduce polybutadiene branches with molecular weight of 5k - 20k through anionic polymerization to form a three-dimensional network structure, with a grafting rate of 0.8% - 2.0%.

3. The preparation method of a non-reactive hot melt adhesive according to claim 1, characterized in that, The softening point of the hydrogenated C9 petroleum resin is 100 - 145°C, the residual double bond rate < 5%, and the mass ratio with the terpene phenol resin is 2:1; the softening point of the terpene phenol resin is 90 - 120°C, and it contains phenolic hydroxyl polar groups.

4. The preparation method of a non-reactive hot melt adhesive according to claim 1, characterized in that, The compounding composition of the tackifying resin is: 40 - 60 parts of hydrogenated C9 petroleum resin, 20 - 30 parts of terpene phenol resin, and 0 - 5 parts of epoxidized polybutadiene liquid rubber.

5. The preparation method of a non-reactive hot melt adhesive according to claim 1, characterized in that, The preparation method further comprises the following steps: Add 0.1 - 0.5% of peroxide vulcanizing agent for dynamic vulcanization treatment in the later stage of melt mixing, and adopt a gradient heating method during mixing: control the temperature in segments at 150°C → 170°C → 190°C.

6. The preparation method of a non-reactive hot melt adhesive according to claim 1, characterized in that, The hot melt adhesive further comprises functional additives: 0.5 - 1.5 parts of silane coupling agent KH-550, 1 - 3 parts of nano-silica or 0 - 2 parts of montmorillonite hybrid filler, and the montmorillonite is modified by KH-550.

7. The preparation method of a non-reactive hot melt adhesive according to claim 1, characterized in that, The melt index of the POE is 10 - 400 g / 10min, the melt viscosity of the APAO at 190°C is 1.2 - 12 mPa·s, and the styrene content of the SEBS and / or SIS is 15% - 30%.

8. The preparation method of a non-reactive hot melt adhesive according to claim 1, characterized in that The grafting rate of the maleic anhydride grafted modified polyolefin resin is 0.5% - 2.0%, the addition amount is 5 - 15 parts, and at least 5 parts of epoxidized polybutadiene liquid rubber are contained in the tackifying resin.

9. A non-reactive hot melt adhesive prepared by the method according to any one of claims 1-8, characterized in that, The hot melt adhesive meets the following performance indicators: Peel strength ≥ 25 N / 25 mm, shear strength ≥ 4.0 MPa, electrolyte dissolution rate ≤ 1.0%, and the adhesion performance retention rate after high and low temperature cycling (-40°C to 85°C) > 90%.

10. The non-reactive hot melt adhesive according to claim 9, characterized in that, The hot melt adhesive further comprises a hydrogenated dendritic random polymer, and the hydrogenated dendritic random polymer is a branched polystyrene-conjugated diene block copolymer with a bimodal molecular weight distribution and a number average molecular weight of 80,000 - 250,000.

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