A polyester hot melt adhesive and an insulating film made from the polyester hot melt adhesive.

Abstract

This invention discloses a polyester hot melt adhesive, wherein the adhesive layer is obtained by drying an adhesive coating liquid, which comprises the following components by weight: 70-90 parts polyester resin, 10-30 parts prepolymer resin, 5-15 parts other resins, 40-60 parts flame retardant filler, 1-2 parts anti-hydrolysis agent, and 10-20 parts solvent. The polyester resin is a linear saturated polyester with the following characteristics: Tg: 10-20℃, hydroxyl value: 1-5 mgKOH / g, acid value: <3 mgKOH / g, molecular weight Mn: 15000-30000 g / mol, with 70-90 parts added. The insulating film substrate of this invention uses one of PET, PI, and PEN, and has two types of insulating films: single-sided and double-sided. The single-sided film is used for bonding and insulating cylindrical battery series components, and the double-sided insulating film is used for bonding and fixing flat cables for signal acquisition. The film using this polyester hot melt adhesive has high processing efficiency, strong adhesion performance, can be processed using automated production lines, and can simultaneously meet the requirements of flame retardancy, temperature resistance, high temperature and high humidity resistance, and high and low temperature impact resistance.

Description

Technical Field

[0001] This invention belongs to the field of adhesive tape technology, and particularly relates to a polyester hot melt adhesive and an insulating film made from the polyester hot melt adhesive. Background Technology

[0002] Currently, cylindrical batteries for new energy vehicles have a high degree of standardization, mature manufacturing, high battery consistency, good overall stability of the battery pack after PACK assembly, fast charging and discharging, high charging efficiency, and high output power; however, since cylindrical batteries require a large number of individual cells to be combined, this increases the complexity and difficulty of the battery control system.

[0003] Currently, there are two types of insulating tape used in the electrode series connection and current signal acquisition integration board of cylindrical battery control systems. One type uses ordinary pressure-sensitive tape, which only has an insulating function. Pressure-sensitive tape is not flame-retardant, has weak adhesive strength with a peel force of only 1-2N / 25mm, and poor weather resistance and temperature resistance. It is prone to vibration and falling off during the transportation of the integration board and vehicle use, leading to insulation failure, battery short circuit, and fire. The other type uses ordinary hot-melt flame-retardant tape, which has poor temperature resistance, high temperature and humidity resistance, and high and low temperature impact resistance. It is especially prone to falling off in low temperature environments, which cannot guarantee the 10-15 year service life of new energy vehicles.

[0004] To address the shortcomings of existing technologies, this invention provides a polyurethane adhesive and a hot-pressed insulating film made from this adhesive. Compared to traditional hot-melt insulating films, the insulating film of this invention can achieve high bonding strength with films such as PET and PI, as well as metals such as aluminum, copper, and steel, through short-time hot pressing or hot roll bonding processes. It also exhibits excellent high-temperature resistance, high-temperature and high-humidity resistance, and high- and low-temperature impact resistance, making it highly competitive in the market. Summary of the Invention

[0005] The purpose of this invention is to provide a polyester hot melt adhesive and an insulating film using the hot melt adhesive. The polyester hot melt adhesive film has high processing efficiency, strong bonding performance, can be processed using automated production lines, and can simultaneously meet the requirements of flame retardancy, temperature resistance, high temperature and high humidity resistance, and high and low temperature impact resistance.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a polyester hot melt adhesive, wherein the adhesive layer is obtained by drying an adhesive coating liquid, the coating liquid comprising the following components in parts by weight:

[0007] The composition includes 70-90 parts polyester resin, 10-30 parts prepolymer resin, 5-15 parts other resins, 40-60 parts flame retardant filler, 1-2 parts anti-hydrolysis agent, and 10-20 parts solvent.

[0008] The following is a further improvement to the above technical solution:

[0009] 1. In the above scheme, the polyester resin is a linear saturated polyester with the following characteristics: Tg: 10~20℃, hydroxyl value: 1~5mgKOH / g, acid value: <3mgKOH / g, molecular weight Mn: 15000~30000g / mol, and 70~90 parts are added. By using a high molecular weight linear saturated polyester, the flexibility and high-strength adhesive performance of the hot melt adhesive can be guaranteed.

[0010] 2. In the above scheme, the self-made prepolymer resin is prepared by prepolymerizing hydroxyl-terminated polyester polyol resin and flexible isocyanate at a molar equivalent ratio of NCO (isocyanate group) to OH (hydroxyl group) of 0.6 to 1, and adding 10 to 30 parts by weight. Prepolymerizing the resin helps to control the amount of hot melt adhesive overflow and the processing window, and at the same time can make the insulating film have excellent adhesion and hydrolysis resistance.

[0011] 3. In the above scheme, the hydroxyl-terminated polyester polyol resin is characterized by: Tg: 50~60℃, acid value: ≤10mgKOH / g; hydroxyl value: 40~75mgKOH / g, molecular weight Mn: 2000~4000g / mol.

[0012] 4. In the above scheme, the flexible isocyanate is characterized by using aliphatic polyisocyanates, such as monomers and polymers of hexamethylene diisocyanate (HDI) and isoflavone diisocyanate (IPDI).

[0013] 5. The preparation method of the self-made prepolymer resin in the above scheme is as follows: Add hydroxyl-terminated polyester polyol resin (Tg: 50-60℃, molecular weight Mn: 2000-4000g / mol; acid value: ≤10mgKOH / g; hydroxyl value: 40-75mgKOH / g) and dehydrated butanone solvent to a stainless steel reactor equipped with a stirrer, cooling pipe, and thermometer. Nitrogen protection is used throughout the process. Stirring begins while simultaneously raising the temperature to 70℃. Stir until the resin is completely dissolved, maintain the constant temperature, and then add a catalyst. 0.01% dibutyltin dilaurate was stirred evenly, and then a certain proportion of flexible isocyanate (HDI) was slowly added over a period of 1 hour. After the curing agent was added, the temperature was raised to 80°C and maintained for 2-3 hours. Then, a sample was taken to test the infrared spectrum (FT-IR) and observe whether NCO at 2260 cm⁻¹ had disappeared. If it had disappeared, it meant that the NCO reaction was complete. The temperature was lowered to 40°C while maintaining a nitrogen atmosphere, and methyl ethyl ketone was added to adjust the solid content of the prepolymer resin. The prepolymer resin was then produced.

[0014] 6. In the above scheme, the flame retardant is characterized by using one or a mixture of two of phosphorus (P)-based flame retardants and nitrogen (N)-based flame retardants to ensure that the insulating film has certain flame retardant properties.

[0015] 7. In the above scheme, the other resins are one or more of epoxy resin and its modified products, rosin resin and its modified products, terpene resin and its modified products, petroleum resin, phenolic resin, etc., to ensure that the insulating film has excellent adhesive properties.

[0016] 8. In the above scheme, the anti-hydrolysis agent is carbodiimide monomer and its modified polymer; used to improve the hydrolysis resistance of the hot melt adhesive.

[0017] To achieve the above objectives, another technical solution adopted by the present invention is: a method for preparing a polyester hot melt adhesive, comprising the following steps:

[0018] (1) Mix the polyester resin, prepolymer resin, other resins and solvent for 20 minutes;

[0019] (2) Slowly add flame retardant filler to the glue, and at the same time use a high-speed disperser to disperse at high speed for 1 hour, then add anti-hydrolysis agent and continue to disperse for 10 minutes.

[0020] (3) Grind the dispersed adhesive using a yarn mill, and after grinding, discharge the material to obtain polyester hot melt adhesive.

[0021] The following is a further improvement to the above technical solution:

[0022] 1. In the above scheme, polyester hot melt adhesive is made into single-sided adhesive film and double-sided adhesive film. The hot melt adhesive insulating film is used for the integration of current transmission and signal acquisition board of new energy cylindrical battery, mainly playing the role of insulation and flame retardancy.

[0023] Furthermore, the preparation method of the single-sided insulating film is as follows: a 50μm thick PET film is pre-corona treated, a polyester hot melt adhesive is coated on the corona-treated surface of the PET film, the solvent is dried at 100℃ for 5mins, the thickness (dry) of the adhesive layer is 50μm, and a single-sided insulating film is made.

[0024] Furthermore, the preparation method of the double-sided insulating film is as follows: after laminating a protective film onto the prepared single-sided insulating film, a layer of polyester hot melt adhesive with a thickness (dry) of 50μm is applied to the other side to form a double-sided insulating film.

[0025] 2. In the above scheme, the substrate is one of PET (polyethylene terephthalate), PI (polyimide), or PEN (polyethylene naphthalate). The preferred film thickness is 15μm to 75μm.

[0026] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0027] 1. The polyester hot melt adhesive of this invention can quickly bond with metal materials. The insulating film substrate uses one of PET (polyethylene terephthalate), PI (polyimide), and PEN (polyethylene naphthalate). There are single-sided and double-sided insulating films. The single-sided film is used for bonding and insulating cylindrical battery series components, and the double-sided insulating film is used for bonding and fixing flat cables for signal acquisition. The film using this polyester hot melt adhesive has high processing efficiency, strong bonding performance, can be processed using automated production lines, and can simultaneously meet the requirements of flame retardancy, temperature resistance, high temperature and high humidity resistance, and high and low temperature impact resistance.

[0028] 2. The insulating film of the present invention can achieve high bonding strength with films such as PET and PI, as well as metals such as aluminum, copper, and steel through short-time hot pressing or hot roller pressing bonding processes. At the same time, it has excellent high temperature resistance, high temperature and high humidity resistance, and high and low temperature impact resistance. Detailed Implementation

[0029] The present invention will be further described below with reference to embodiments:

[0030] Table 1 lists the raw materials for preparing prepolymer resins.

[0031] Table 1

[0032]

[0033]

[0034] Example

[0035] Example 1

[0036] Single-sided hot melt adhesive film, using PET substrate film thickness 50μm, adhesive layer thickness: 50μm;

[0037] Hot melt adhesive weight ratio: Polyester resin ES-360 80 parts, prepolymer resin R1 20 parts, flame retardant filler OP935 50 parts, other resin GB120 10 parts, anti-hydrolysis agent 1010 1 part, solvent MEK 10 parts.

[0038] Example 2

[0039] Single-sided hot melt adhesive film, using PET substrate film thickness 50μm, adhesive layer thickness: 50μm;

[0040] Hot melt adhesive weight ratio: Polyester resin ES-360 90 parts, prepolymer resin R2 10 parts, flame retardant filler OP935 50 parts, other resin GB120 10 parts, anti-hydrolysis agent 1.5 parts of 1010 and 10 parts of solvent MEK.

[0041] Example 3

[0042] Single-sided hot melt adhesive film, using PET substrate film thickness 50μm, adhesive layer thickness: 50μm;

[0043] Hot melt adhesive weight ratio: Polyester resin ES-360 80 parts, prepolymer resin R3 20 parts, flame retardant filler OP935 45 parts, other resin GB120 10 parts, anti-hydrolysis agent 1010 1 part, solvent MEK 10 parts.

[0044] Example 4

[0045] Single-sided hot melt adhesive film, using PET substrate film thickness 50μm, adhesive layer thickness: 50μm;

[0046] Hot melt adhesive weight ratio: Polyester resin ES-360 75 parts, prepolymer resin R4 25 parts, flame retardant filler OP935 55 parts, other resins GB120 8 parts, anti-hydrolysis agent 1010 1 part, solvent MEK 10 parts.

[0047] Example 5

[0048] Single-sided hot melt adhesive film, using PET substrate film thickness 50μm, adhesive layer thickness: 50μm;

[0049] Hot melt adhesive weight ratio: Polyester resin ES-360 80 parts, prepolymer resin R5 20 parts, flame retardant filler OP935 42 parts, other resin GB120 15 parts, anti-hydrolysis agent 1010 1 part, solvent MEK 10 parts.

[0050] Example 6

[0051] Single-sided hot melt adhesive film, using PET substrate film thickness 50um, adhesive layer thickness: 50um;

[0052] Hot melt adhesive weight ratio: Polyester resin AL072 85 parts, prepolymer resin R3 15 parts, flame retardant filler OP935 50 parts, other resins GB120 15 parts, anti-hydrolysis agent 1010 1 part, solvent MEK 10 parts.

[0053] Example 7

[0054] Single-sided hot melt adhesive film, using PET substrate film thickness 50um, adhesive layer thickness: 50um;

[0055] Hot melt adhesive weight ratio: Polyester resin AL072 90 parts, prepolymer resin R5 10 parts, flame retardant filler OP935 40 parts, other resins GB120 10 parts, anti-hydrolysis agent 1010 1 part, solvent MEK 10 parts.

[0056] Example 8

[0057] Double-sided hot melt adhesive film, using PET substrate film thickness 50um, first layer adhesive thickness: 50um, second layer adhesive thickness: 50um;

[0058] Hot melt adhesive weight ratio: Polyester resin AL072 70 parts, prepolymer resin R5 30 parts, flame retardant filler OP935 60 parts, other resins GB120 5 parts, anti-hydrolysis agent 1010 2 parts, solvent MEK 10 parts.

[0059] The above components are specifically:

[0060] ES-360, polyester resin, SK Chemicals, South Korea, hydroxyl value: 3mgKOH / g, acid value: <3mgKOH / g, Tg: 17℃, molecular weight Mn: 28000.

[0061] AL072, polyester resin, Hanhai New Materials, hydroxyl value: 4mgKOH.g, acid value: <3mgKOH / g, Tg: 12℃, molecular weight Mn: 26000.

[0062] VYLON 220, polyester resin, Toyobo, Japan, hydroxyl value: 50mgKOH / g, acid value: <2mgKOH / g, Tg: 53℃, molecular weight Mn: 3000.

[0063] GB120, Rosin Resin, Arakawa Chemical, Acid Value: 10~20mgKOH / g, Softening Point: 117-126℃.

[0064] OP935, phosphonite flame retardant, Clariant Chemicals;

[0065] 1010, carbodiimide, Langyi Technology;

[0066] DBTDL, Dibutyltin Dilaurate, Aladdin Chemicals, China;

[0067] TPA100, isocyanate resin, HDI trimer, Asahi Kasei, Japan;

[0068] Comparative Example

[0069] Comparative Example 1: Single-sided hot melt adhesive film, using a PET substrate film with a thickness of 50 μm and an adhesive layer thickness of 50 μm.

[0070] Hot melt adhesive weight ratio: Polyester resin ES-360 80 parts, prepolymer resin R6 20 parts, flame retardant filler OP935 50 parts, other resin GB120 10 parts, anti-hydrolysis agent 1010 1 part, solvent MEK 10 parts.

[0071] Comparative Example 2: Single-sided hot melt adhesive film, using a PET substrate film with a thickness of 50 μm and an adhesive layer thickness of 50 μm.

[0072] Hot melt adhesive weight ratio: Polyester resin ES-360 80 parts, prepolymer resin R7 20 parts, flame retardant filler OP935 50 parts, other resin GB120 10 parts, anti-hydrolysis agent 1010 1 part, solvent MEK 10 parts.

[0073] Comparative Example 3: Single-sided hot melt adhesive film, using a PET substrate film with a thickness of 50 μm and an adhesive layer thickness of 50 μm.

[0074] Hot melt adhesive weight ratio: Polyester resin ES-360 100 parts, flame retardant filler OP935 50 parts, other resin GB120 10 parts, anti-hydrolysis agent 1010 1 part, solvent MEK 10 parts.

[0075] Comparative Example 4: Single-sided hot melt adhesive film, using a PET substrate film with a thickness of 50 μm and an adhesive layer thickness of 50 μm.

[0076] Hot melt adhesive weight ratio: Polyester resin ES-360 60 parts, prepolymer resin R4 40 parts, flame retardant filler OP935 50 parts, other resin GB120 10 parts, anti-hydrolysis agent 1010 1 part, solvent MEK 10 parts.

[0077]

[0078] ◎: Indicates optimal overall performance; ○: Indicates OK performance, meeting usage requirements;

[0079] △: indicates poor performance; ×: indicates extremely poor performance.

[0080] Evaluation method:

[0081] Peel strength (N / mm): Cut the adhesive film into 300mm wide and 150mm long pieces, fix the cut adhesive film onto 0.12mm thick aluminum foil, use a temperature of 140~160℃ / hot pressing time of 1min / pressure of 0.5Mpa for hot pressing, cool to room temperature and test 180° peel at a speed of 100mm / min.

[0082] Excess adhesive (mm): Cut the adhesive film into 3 samples of 10cm*10cm size, punch holes using a punching machine, attach the punched samples to 0.12mm thick aluminum foil, and hot press at a temperature of 140~160℃ / time 1min / pressure of 0.5Mpa. After hot pressing, test the amount of excess adhesive at the punched position.

[0083] High temperature and high humidity aging test (85℃×85%RH / 1000H): Same as the sample preparation method in 1 and 2, put the sample into the high temperature and high humidity environment chamber for 1000H, take it out and cool it to room temperature, and test the peel strength, peel at 180°, at a speed of 100mm / min.

[0084] Thermal shock aging test (-40℃~105℃ / 1000 cycles): Same as sample preparation method 1, place the sample in thermal shock environment chamber for 1000H, -40℃ / 0.5H, 105℃ / 0.5H, with the hot and cold switching time within 2mins. After 1000 cycles, take it out and cool it to room temperature, and test the peel strength, 180° peel, at a speed of 100mm / min.

[0085] High temperature aging test (125℃ aging for 1000H): Same as the sample preparation method in 1, put the sample into a high temperature oven for 1000H, after aging for 1000H, take it out and cool it to room temperature, and test the peel strength, peel at 180°, at a speed of 100mm / min.

[0086] Based on the above experimental results, it can be seen that the initial bonding strength of Comparative Examples 1 and 2 is significantly lower than that of the Example, and the bonding strength after thermal shock is also lower than the requirements for actual use. The bonding strength of Comparative Examples 1, 2, and 3 after aging at 85°C and 85%RH for 1000 hours and after aging at 125°C for 1000 hours also does not meet the requirements for use. The amount of adhesive overflow in Comparative Examples 1, 3, and 4 is too high, which has seriously affected the actual use effect.

[0087] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A polyester hot melt adhesive characterized by: The adhesive comprises the following components by weight: polyester resin 70~90 parts, prepolymer resin 10~30 parts, other resin 5~15 parts, flame retardant filler 40~60 parts, hydrolysis inhibitor 1~2 parts, solvent 10~20 parts; The polyester resin is a linear saturated polyester with the following characteristics: Tg: 10~20℃, hydroxyl value: 1~5mgKOH / g, acid value: <3mgKOH / g, molecular weight Mn: 15000~30000g / mol, and the addition amount is 70~90 parts; The prepolymer resin is prepared by prepolymerization of a hydroxyl-terminated polyester polyol resin and a flexible isocyanate with a molar ratio of NCO to OH of 0.6~1; The hydroxyl-terminated polyester polyol resin has the following characteristics: Tg: 50~60℃, acid value: ≤10mgKOH / g; hydroxyl value: 40~75mgKOH / g, and molecular weight Mn: 2000~4000g / mol; The flexible isocyanate is an aliphatic polyisocyanate; The other resin is a mixture of one or more of epoxy resin and its modified product, rosin resin and its modified product, terpene resin and its modified product, petroleum resin, and phenolic resin.

2. The polyester hot melt adhesive according to claim 1, characterized in that: The preparation method of the prepolymer resin comprises the following steps: adding a hydroxyl-terminated polyester polyol resin and dehydrated butanone solvent into a stainless steel reaction kettle with a stirrer, cooling tube, and thermometer, using nitrogen protection throughout the process, starting stirring while heating to 60~70℃, stirring until the resin is completely dissolved, adding a catalyst at a constant temperature, stirring uniformly, slowly adding a certain proportion of flexible isocyanate, controlling the addition time at 0.5~1H, heating to 70~80℃ after the addition is completed, keeping the temperature and continuing to react for 2~3H, then sampling and testing infrared spectrum to observe whether NCO at 2260cm-1 has disappeared, which represents that NCO reaction is complete; keeping nitrogen atmosphere, cooling to 35~45℃, adding butanone to adjust the solid content of the prepolymer resin to 45%, and completing the preparation of the prepolymer resin.

3. The polyester hot melt adhesive of claim 1, wherein: The flame retardant filler is a mixture of one or both of phosphorus-based flame retardant and nitrogen-based flame retardant; The hydrolysis inhibitor is a carbodiimide monomer and its modified polymer.

4. A process for the preparation of the polyester hot-melt adhesive according to claim 1, characterized by: The method comprises the following steps: blending and stirring the polyester resin, prepolymer resin, other resin, and solvent uniformly; slowly adding the flame retardant filler into the glue while using a high-speed disperser for high-speed dispersion, then adding the hydrolysis inhibitor and continuing to disperse; grinding the dispersed glue using a yarn grinder, discharging after grinding is completed to obtain the polyester hot melt adhesive.

5. A method of preparing an insulation film using the polyester hot melt adhesive of claim 1, characterized by: The polyester hot melt adhesive is made into single-sided adhesive film or double-sided adhesive film; The preparation method of the single-sided adhesive film is as follows: pre-treating a PET film by corona treatment, coating the polyester hot melt adhesive on the corona-treated surface of the PET film, and drying to prepare the single-sided adhesive film; The preparation method of the double-sided adhesive film is as follows: compounding a protective film on the prepared single-sided insulating adhesive film, then coating another layer of polyester hot melt adhesive on the other side to prepare the double-sided adhesive film.

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