Hot melt adhesive film for FFC (flexible flat cable) wire and preparation method of hot melt adhesive film

Abstract

The invention discloses a hot melt adhesive film for a flexible flat cable (FFC), which comprises a base material and a hot melt adhesive layer which are sequentially connected from bottom to top, and the hot melt adhesive layer is obtained by thermally curing a hot melt adhesive coated on the base material; the hot melt adhesive comprises the following raw materials: TPU resin, polybutadiene polyol, a curing reaction accelerator, a filler and a solvent, the TPU resin comprises any one of polyether type TPU resin and polycarbonate type TPU. The hot melt adhesive film for the FFC wire rod provided by the invention not only has excellent hydrolysis resistance and metal adhesion, but also has excellent acid resistance, low temperature resistance and bending resistance, so as to overcome the defects in the prior art.

Description

Technical Field

[0001] The invention relates to the field of film manufacturing, and in particular to a hot melt adhesive film for FFC wires and a preparation method thereof. Background Art

[0002] FFC (Flexible Flat Cable) is made by hot-melt adhesive film and extremely thin tinned flat copper wire on a substrate through an automatic roller-pressing laminating machine. It has the advantages of being soft, able to bend and fold at will, thin, small in size, and easy to solve electromagnetic shielding. It is widely used in signal transmission of various consumer products such as printers, plotters and copiers.

[0003] With the continuous improvement of FFC wire technology and the improvement of people's requirements for FFC wire, higher requirements are also put forward for hot melt adhesive film, one of the raw materials of FFC wire. Specifically, on the one hand, the hot melt adhesive film is required to have good acid resistance to avoid the hot melt adhesive film being easily corroded by acidic substances due to its poor acid resistance when the FFC wire is used in an acidic environment, which will cause the performance of the hot melt adhesive film to decline or even fail, and thus fail to effectively wrap the tinned flat copper wire, thereby causing the FFC to be scrapped and unable to perform its function; on the other hand, it is required to have low temperature resistance to avoid the hot melt adhesive film from becoming hard and brittle in a low temperature use environment, which will make the hot melt adhesive film easily lose its original bonding properties, resulting in stratification between the hot melt adhesive film and the tinned flat copper wire, making the hot melt adhesive film's wrapping of the tinned flat copper wire worse, which is also easy to cause the FFC to be scrapped. In addition, the hot melt adhesive film needs to have sufficient flex resistance to avoid cracking or damage due to insufficient flex resistance during frequent bending and movement. This will not only cause the performance of the hot melt adhesive film to fail, but also make it easy for water vapor in the external environment to enter the FFC through cracks or damage, causing the tinned flat copper wire to be oxidized and the FFC wire to be scrapped.

[0004] The existing hot melt adhesive film for FFC wire mainly includes a substrate and a hot melt adhesive layer obtained by coating the hot melt adhesive on the substrate and thermally curing it. Therefore, the acid resistance, low temperature resistance and flexibility resistance of the hot melt adhesive film for FFC wire mainly depend on the hot melt adhesive. However, the existing hot melt adhesive generally uses polyester resin as the main resin, but the ester group in the polyester resin is easily hydrolyzed in an acidic environment, resulting in the poor acid resistance of the obtained hot melt adhesive film. In addition, since the movement of the molecular chain of the polyester resin is hindered in a low temperature environment, its toughness is reduced, and it is prone to embrittlement and cracking, which also leads to the poor low temperature resistance of the hot melt adhesive film. That is, it is difficult for the hot melt adhesive film obtained using the existing hot melt adhesive to take into account the acid resistance, low temperature resistance and flexibility resistance at the same time, which seriously limits the use of the hot melt adhesive film. Summary of the invention

[0005] One of the purposes of the present invention is to provide a hot melt adhesive film for FFC wires, which not only has excellent hydrolysis resistance and metal adhesion, but also has excellent acid resistance, low temperature resistance and flexibility resistance, so as to overcome the shortcomings of the prior art.

[0006] The second purpose of the present invention is to propose a method for preparing a hot melt adhesive film for FFC wire. The preparation method is simple and easy to operate, ensuring that the obtained hot melt adhesive film for FFC wire not only has excellent hydrolysis resistance and metal adhesion, but also has excellent acid resistance, low temperature resistance and flexibility resistance, thereby meeting actual usage requirements.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] A hot melt adhesive film for FFC wires, comprising a substrate and a hot melt adhesive layer connected in sequence from bottom to top, wherein the hot melt adhesive layer is obtained by thermally curing the hot melt adhesive coated on the substrate;

[0009] The hot melt adhesive comprises the following raw materials: TPU resin, polybutadiene polyol, curing reaction accelerator, filler and solvent;

[0010] The TPU resin includes any one of a polyether TPU resin and a polycarbonate TPU resin.

[0011] Furthermore, calculated by weight, the hot melt adhesive includes the following raw materials: 35-40 parts of TPU resin, 5-15 parts of polybutadiene polyol, 1-2 parts of curing reaction accelerator, 6-10 parts of filler and 40-53 parts of solvent.

[0012] Furthermore, the polybutadiene polyol is any one of single-terminal hydroxyl polybutadiene and double-terminal hydroxyl polybutadiene.

[0013] Furthermore, the polybutadiene polyol is a double-terminal hydroxyl polybutadiene.

[0014] Further, the filler includes fumed silica and titanium dioxide;

[0015] Calculated by weight, the hot melt adhesive includes the following raw materials: 35-40 parts of TPU resin, 5-15 parts of polybutadiene polyol, 1-2 parts of curing reaction accelerator, 3-5 parts of fumed silica, 3-5 parts of titanium dioxide and 40-53 parts of solvent.

[0016] Further, the curing reaction accelerator includes any one or more combinations of 2,4,6-tris(dimethylaminomethyl)phenol, N-methyl-N-hydroxyethyl-p-toluidine, N,N-dimethyl-p-toluidine, N,N-diethyl-p-toluidine, N,N-dihydroxyethylaniline, N,N-di(2-hydroxypropyl)aniline, triethylamine, triethanolamine and o-hydroxybenzyldimethylamine.

[0017] Further, the substrate is a PET film;

[0018] The thickness of the PET film is 25-50 μm; the thickness of the hot melt adhesive layer is 21-80 μm.

[0019] A method for preparing a hot melt adhesive film for FFC wires, for preparing the hot melt adhesive film for FFC wires, comprises the following steps:

[0020] A. Mix the formulated amount of TPU resin, polybutadiene polyol, curing reaction accelerator, filler and solvent, stir them evenly, and grind them to obtain a hot melt adhesive;

[0021] B. Coating hot melt adhesive on the surface of the substrate, forming a hot melt adhesive layer after thermal curing, and obtaining a hot melt adhesive film for FFC wire.

[0022] Furthermore, in step A, the stirring speed is 800 to 2000 r / min, and the stirring time is 5 to 10 min;

[0023] The grinding time of the grinding is 30 to 50 minutes.

[0024] Furthermore, step B specifically includes: performing corona treatment on the surface of the substrate, coating the corona treated surface of the substrate with hot melt adhesive, forming a hot melt adhesive layer after thermal curing, and obtaining a hot melt adhesive film for FFC wires.

[0025] The technical solution provided by the present invention may include the following beneficial effects:

[0026] 1. Polybutadiene polyol, polyether TPU resin and polycarbonate TPU all have excellent elasticity. In the process of repeated bending and stretching, the above raw materials can maintain good mechanical properties and elasticity and are not prone to breakage or deformation. Therefore, in this technical solution, by adding TPU resin and polybutadiene polyol to the hot melt adhesive at the same time, the hot melt adhesive is made resistant to bending by utilizing the mutual cooperation of polybutadiene polyol and TPU resin, thereby giving the hot melt adhesive film excellent flex resistance.

[0027] 2. The molecular chain structure of polybutadiene polyol and polyether TPU resin is flexible and easy to rotate and bend. In low temperature environment, polyether TPU can still maintain good elasticity and toughness, and is not easy to become brittle or break, which gives it excellent low temperature toughness. At the same time, polycarbonate TPU can still maintain good mechanical properties and elasticity in general low temperature environment, which also makes it have good low temperature resistance. Therefore, when TPU resin and polybutadiene polyol are added to the hot melt adhesive formula at the same time, the hot melt adhesive has low temperature resistance through the mutual cooperation of TPU resin and polybutadiene polyol, thereby giving the hot melt adhesive film excellent low temperature resistance.

[0028] 3. Polybutadiene polyol contains multiple hydroxyl groups, all of which have high reactivity, while TPU resin is usually a linear polymer material generated by the reaction of isocyanate, macromolecular polyol and chain extender. In addition, in the process of forming TPU resin, isocyanate is usually difficult to react completely with macromolecular polyol and chain extender, so that isocyanate groups usually remain inside the TPU resin. When the TPU resin is heated and melted, the structure of the TPU resin becomes more stretched, so that the isocyanate groups originally buried inside the TPU resin molecules are gradually exposed to the surface of the TPU resin and cross-linked with the hydroxyl groups in the polybutadiene polyol, thereby enhancing the cohesion and adhesion of the hot melt adhesive, thereby improving the metal adhesion of the hot melt adhesive and giving the hot melt adhesive film a higher metal adhesion. DETAILED DESCRIPTION

[0029] The technical solution provides a hot melt adhesive film for FFC wires, comprising a substrate and a hot melt adhesive layer connected in sequence from bottom to top, wherein the hot melt adhesive layer is obtained by thermally curing the hot melt adhesive coated on the substrate;

[0030] The hot melt adhesive comprises the following raw materials: TPU resin, polybutadiene polyol, curing reaction accelerator, filler and solvent;

[0031] The TPU resin includes any one of a polyether TPU resin and a polycarbonate TPU resin.

[0032] In view of the shortcomings of the existing hot-melt adhesive film for FFC wires that are difficult to meet the actual use needs, this solution proposes a hot-melt adhesive film for FFC wires, including a substrate and a hot-melt adhesive layer connected in sequence from bottom to top. By optimizing the hot-melt adhesive formula, the hot-melt adhesive film for FFC wires not only has excellent hydrolysis resistance and metal adhesion, but also has excellent acid resistance, low temperature resistance and flexibility resistance, thereby meeting the actual use needs.

[0033] Specifically, existing hot melt adhesives generally use polyester resin as the main resin. However, due to the defects of polyester resin itself, the hot melt adhesive film prepared using hot melt adhesive using polyester resin as the main resin is difficult to simultaneously take into account acid resistance, low temperature resistance and flexibility resistance, which seriously limits the use of hot melt adhesive film.

[0034] In order to overcome the above-mentioned defects, the raw materials of the hot melt adhesive of the present technical solution include TPU resin, polybutadiene polyol, curing reaction accelerator, filler and solvent. Among them, the chemical structure of polybutadiene polyol itself is relatively stable, and the chemical bonds in its molecular chain are not easily destroyed by acidic substances, and it has a certain resistance to the corrosion of acidic substances; at the same time, when polybutadiene polyol is exposed to an acidic environment, a protective film will quickly form on its surface to prevent acidic substances from further corroding its interior. The above two aspects interact with each other to make the hot melt adhesive with added polybutadiene polyol acid-resistant, thereby giving the hot melt adhesive film excellent acid resistance.

[0035] Furthermore, the TPU resin (i.e., thermoplastic polyurethane elastomer) includes any one of polyether TPU resin and polycarbonate TPU. Polybutadiene polyol, polyether TPU resin, and polycarbonate TPU all have excellent elasticity. In the process of repeated bending and stretching, the above raw materials can maintain good mechanical properties and elasticity, and are not prone to breakage or deformation. Therefore, in the technical solution, by adding TPU resin and polybutadiene polyol to the hot melt adhesive at the same time, the hot melt adhesive is made resistant to flex by utilizing the mutual cooperation of polybutadiene polyol and TPU resin, thereby giving the hot melt adhesive film excellent flex resistance.

[0036] Furthermore, the molecular chain structures of polybutadiene polyol and polyether TPU resin are flexible and easy to rotate and bend. In low-temperature environments, polyether TPU can still maintain good elasticity and toughness, and is not prone to brittleness or breakage, giving it excellent low-temperature toughness. At the same time, polycarbonate TPU can still maintain good mechanical properties and elasticity in general low-temperature environments, which also gives it good low-temperature resistance. Therefore, when TPU resin and polybutadiene polyol are added to the hot melt adhesive formula at the same time, the hot melt adhesive has low-temperature resistance through the mutual cooperation of TPU resin and polybutadiene polyol, thereby giving the hot melt adhesive film excellent low-temperature resistance.

[0037] Secondly, compared with polyester resin, polybutadiene polyol does not contain ester bonds in its molecular chain, which avoids the defect of poor hydrolysis resistance caused by hydrolysis of ester groups, making it have better hydrolysis resistance.

[0038] At the same time, polyether TPU resin and polycarbonate TPU itself contain hydrophilic ether groups, which can stably exist in aqueous systems, making both of them have excellent hydrolysis resistance. Therefore, the technical solution uses the mutual cooperation of polybutadiene polyol and TPU resin to make the hot melt adhesive have excellent hydrolysis resistance, thereby giving the hot melt adhesive film excellent hydrolysis resistance. In addition, polycarbonate TPU has a large number of carbonate groups in its molecules, which makes it have higher cohesive energy, thereby giving it excellent adhesion. Therefore, when polycarbonate TPU resin is used as the TPU resin of hot melt adhesive, it is beneficial to increase the metal adhesion of the hot melt adhesive.

[0039] Thirdly, polybutadiene polyol contains multiple hydroxyl groups, all of which have high reactivity, while TPU resin is usually a linear polymer material generated by the reaction of isocyanate, macromolecular polyol and chain extender. In addition, in the process of forming TPU resin, isocyanate is usually difficult to react completely with macromolecular polyol and chain extender, so that isocyanate groups usually remain inside the TPU resin. When the TPU resin is heated and melted, the structure of the TPU resin becomes more stretched, so that the isocyanate groups originally buried inside the TPU resin molecules are gradually exposed to the surface of the TPU resin, and cross-linked with the hydroxyl groups in the polybutadiene polyol, thereby enhancing the cohesion and adhesion of the hot melt adhesive, thereby improving the metal adhesion of the hot melt adhesive and giving the hot melt adhesive film a higher metal adhesion.

[0040] It should be noted that the softening point of polybutadiene polyol is liquid at room temperature and has high fluidity. In addition, the hardness of polybutadiene polyol is extremely low. When polybutadiene polyol is used alone as the resin component of hot melt adhesive, the excessive fluidity makes it difficult to form a stable and coatable hot melt adhesive layer, that is, the coatability is lost; and even if the adhesive layer is barely formed, its extremely low hardness greatly limits the possibility of practical application.

[0041] Compared with polybutadiene polyol, TPU resin has a relatively high softening point and a relatively high viscosity at room temperature. At the same time, the hardness of TPU resin is also relatively high, which is conducive to enhancing the hardness of hot melt adhesive. Therefore, the technical solution adds polybutadiene polyol and TPU resin to the hot melt adhesive formula, so that the hot melt adhesive has both excellent fluidity and sufficient hardness and coatability, thereby ensuring the performance of the hot melt adhesive film.

[0042] Finally, the raw materials of hot melt adhesive also include curing reaction accelerators, which can effectively reduce the activation energy of the thermal curing reaction, thereby effectively promoting the progress of the curing reaction and increasing the speed and degree of the curing reaction.

[0043] Preferably, the solvent includes any one or more combinations of acetone, acetylacetone, butanone, n-hexane, cyclohexane, n-heptane, N-methylpyrrolidone, 1,2-propylene glycol, chloroform, dichloromethane, 1,2-dichloroethane, methanol, ethanol, isopropanol, 1-methoxy-2-propanol, toluene, xylene, ethylenediamine, tert-butanol, n-butanol, n-propanol, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide and carbon tetrachloride.

[0044] It should be noted that the polyether TPU resin may be BASF 1175AW, BASF 1180A, BASF 1185AW, etc., and the specific type is not limited here.

[0045] The polycarbonate TPU may be Wanhua WHT-7180, Wanhua WHT-7190, etc., and the specific type is also not limited here.

[0046] Further explanation: calculated by weight, the hot melt adhesive includes the following raw materials: 35-40 parts of TPU resin, 5-15 parts of polybutadiene polyol, 1-2 parts of curing reaction accelerator, 6-10 parts of filler and 40-53 parts of solvent.

[0047] This technical solution optimizes the ratio of each raw material in the hot melt adhesive, which is conducive to giving full play to the performance of each raw material while reducing costs, and is conducive to achieving the best performance of the hot melt adhesive, thereby improving the performance of the hot melt adhesive film and enhancing its market competitiveness.

[0048] It is further described that the polybutadiene polyol is any one of single-terminal hydroxyl polybutadiene and double-terminal hydroxyl polybutadiene.

[0049] Both the single-terminal hydroxyl polybutadiene and the double-terminal hydroxyl polybutadiene have excellent hydrolysis resistance, acid resistance, low temperature resistance and flexural resistance, and both the single-terminal hydroxyl polybutadiene and the double-terminal hydroxyl polybutadiene contain hydroxyl groups, which can react with the isocyanate groups exposed on the surface of the TPU resin after melting. Therefore, the technical solution preferably includes any one of the single-terminal hydroxyl polybutadiene and the double-terminal hydroxyl polybutadiene, which is conducive to ensuring the performance of the hot melt adhesive film.

[0050] It is further described that the polybutadiene polyol is a double-terminal hydroxyl polybutadiene.

[0051] Since single-terminal hydroxyl polybutadiene has only one hydroxyl functional group, while double-terminal hydroxyl polybutadiene has two hydroxyl functional groups, when reacting with the isocyanate groups exposed on the surface of the molten TPU resin, double-terminal hydroxyl polybutadiene has higher reactivity and can form more chemical bonds, which is more conducive to improving the performance of the hot melt adhesive film.

[0052] It is further described that the filler includes fumed silica and titanium dioxide;

[0053] Calculated by weight, the hot melt adhesive includes the following raw materials: 35-40 parts of TPU resin, 5-15 parts of polybutadiene polyol, 1-2 parts of curing reaction accelerator, 3-5 parts of fumed silica, 3-5 parts of titanium dioxide and 40-53 parts of solvent.

[0054] As a filler, fumed silica can reduce the viscosity of the hot melt adhesive. When combined with a solvent, it helps to improve the stability of the hot melt adhesive formula and avoid agglomeration and precipitation that may lead to a decrease in the performance of the hot melt adhesive.

[0055] Furthermore, titanium dioxide has good whiteness and glossiness, which can make the hot melt adhesive film appear purer and brighter, ensuring the appearance of the hot melt adhesive film. At the same time, titanium dioxide has good weather resistance and UV resistance, which can effectively prevent the hot melt adhesive film from discoloring and aging in outdoor environments, which is conducive to extending the service life of the hot melt adhesive film.

[0056] It is further described that the curing reaction accelerator includes any one or more combinations of 2,4,6-tris(dimethylaminomethyl)phenol, N-methyl-N-hydroxyethyl-p-toluidine, N,N-dimethyl-p-toluidine, N,N-diethyl-p-toluidine, N,N-dihydroxyethylaniline, N,N-di(2-hydroxypropyl)aniline, triethylamine, triethanolamine and o-hydroxybenzyldimethylamine.

[0057] By optimizing the type of curing reaction accelerator, it is not only helpful to select suitable raw materials according to actual needs and improve the flexibility of the formulation, but also helpful to ensure that the preferred curing reaction accelerator can more effectively increase the speed and degree of the curing reaction, thereby improving the performance of the hot melt adhesive film.

[0058] It is further described that the substrate is a PET film;

[0059] The thickness of the PET film is 25-50 μm; the thickness of the hot melt adhesive layer is 21-80 μm.

[0060] In the present technical solution, the substrate is preferably a PET film (polyethylene terephthalate film), which has high strength, low heat shrinkage, high temperature resistance and high stability, which is conducive to making the hot melt adhesive film also have the characteristics of high strength, low heat shrinkage, high temperature resistance and high stability, thereby improving the performance of the hot melt adhesive film.

[0061] Furthermore, the thickness of the PET film is 25-50 μm, which plays a certain supporting role and ensures the strength and hardness of the hot melt adhesive film for FFC wires. In addition, it also avoids the PET film being too thin, which makes the finished product prone to wrinkling.

[0062] Furthermore, the thickness of the hot melt adhesive layer is 21 to 80 μm, which is beneficial for wrapping the metal conductor tinned flat copper wire while reducing costs, thereby preventing the tinned flat copper wire from being exposed to the air and affecting the performance of the FFC wire.

[0063] A method for preparing a hot melt adhesive film for FFC wires, for preparing the hot melt adhesive film for FFC wires, comprises the following steps:

[0064] A. Mix the formulated amount of TPU resin, polybutadiene polyol, curing reaction accelerator, filler and solvent, stir them evenly, and grind them to obtain a hot melt adhesive;

[0065] B. Coating hot melt adhesive on the surface of the substrate, forming a hot melt adhesive layer after thermal curing, and obtaining a hot melt adhesive film for FFC wire.

[0066] The technical solution also proposes a method for preparing a hot-melt adhesive film for FFC wires. The preparation method is simple and easy to operate, ensuring that the obtained hot-melt adhesive film for FFC wires not only has excellent hydrolysis resistance and metal adhesion, but also has excellent acid resistance, low temperature resistance and flexibility resistance, thus meeting actual usage requirements.

[0067] Further, in step A, the stirring speed is 800-2000 r / min, and the stirring time is 5-10 min;

[0068] The grinding time of the grinding is 30 to 50 minutes.

[0069] By limiting the stirring speed and stirring time in step A, it is beneficial to promote the mixing uniformity of the raw materials and ensure the performance of the hot melt adhesive. In addition, grinding is beneficial to further refine the particles, improve the fineness and uniformity of the raw materials, and thus improve the appearance and performance of the final product. Limiting the grinding time to 30 to 50 minutes can ensure that the grinding process will not be damaged or deteriorated due to excessive grinding.

[0070] To further explain, step B specifically includes: performing corona treatment on the surface of the substrate, coating the surface of the substrate after the corona treatment with hot melt adhesive, forming a hot melt adhesive layer after thermal curing, and obtaining a hot melt adhesive film for FFC wire.

[0071] The technical solution performs corona treatment on the surface of the substrate, which is beneficial to increase the adhesion of the substrate surface to the hot melt adhesive layer, thereby improving the performance of the hot melt adhesive film for FFC wires.

[0072] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0073] Performance Testing:

[0074] Hydrolysis resistance: A tinned flat copper wire with a thickness of 0.035 mm and a width of 0.3 mm was pressed with a hot-melt adhesive film at a temperature of 160°C and a pressure of 300 KPa for 3 seconds to obtain an FFC wire test sample. The FFC wire test sample was steamed at a high temperature of 121°C for 72 hours, and the peeling force of the FFC wire test sample after high-temperature steaming was tested using a tensile testing machine with a peeling speed of 50 mm / min. When the peeling value was greater than 30g / 0.3mm, it was qualified.

[0075] Adhesion property: Use hot melt adhesive film to press tinned flat copper wire with a thickness of 0.035mm and a width of 0.3mm for 3s at a temperature of 160℃ and a pressure of 300KPa to obtain the FFC wire test sample; At room temperature (25℃), use a tensile testing machine with a peeling speed of 300mm / min to test the adhesion of a single tinned flat copper wire at the window position of the FFC wire test sample. When the peeling value is greater than 40g / 0.3mm, it is qualified.

[0076] Flexibility: Use hot-melt adhesive film to press tinned flat copper wire with a thickness of 0.035mm and a width of 0.3mm for 3s at a temperature of 160°C and a pressure of 300KPa to obtain an FFC wire test sample, and test the initial resistance value of the FFC wire test sample; at room temperature (25°C), bend the FFC wire test sample 300,000 times at a bending radius of 8mm and a bending frequency of 100 times / min, and test the resistance value of the FFC wire test sample after bending. If the increase in the resistance value of the FFC wire test sample after bending is within 30% of the initial resistance value, it is qualified.

[0077] Low temperature resistance: Use hot melt adhesive film to press tinned flat copper wire with a thickness of 0.035mm and a width of 0.3mm for 3s at a temperature of 160℃ and a pressure of 300KPa to obtain the FFC wire test sample, and test the initial resistance value of the FFC wire test sample; Under low temperature conditions of -40℃, bend the FFC wire test sample 300,000 times with a bending radius of 8mm and a bending frequency of 100 times / min, and test the resistance value of the FFC wire test sample after bending. If the increase in the resistance value of the FFC wire test sample after bending is within 40% of the initial resistance value, it is qualified.

[0078] Acid resistance: A tinned flat copper wire with a thickness of 0.035 mm and a width of 0.3 mm was pressed with a hot melt adhesive film at a temperature of 160°C and a pressure of 300 KPa for 3 seconds to obtain an FFC wire test sample. The FFC wire test sample was placed in a temperature of 35°C and a sodium chloride solution concentration of 5 ％Soak for 72 hours under the conditions. If there is no cracking or damage on the FFC wire test sample after soaking, the acid resistance test is qualified.

[0079] Example 1

[0080] A. 40 parts of polycarbonate TPU, 10 parts of double-terminated hydroxyl polybutadiene, 2 parts of 2,4,6-tris(dimethylaminomethyl)phenol, 4 parts of fumed silica, 4 parts of titanium dioxide and 45 parts of N,N-dimethylformamide were mixed and stirred at a speed of 1000 r / min for 8 minutes, and then ground for 40 minutes to obtain a hot melt adhesive;

[0081] B. The surface of a PET film having a thickness of 25 μm is subjected to corona treatment, and a hot melt adhesive is coated on the surface of the PET film after the corona treatment. After thermal curing, a hot melt adhesive layer having a thickness of 30 μm is formed to obtain a hot melt adhesive film for FFC wires.

[0082] Example 2

[0083] A. 35 parts of polyether TPU resin, 5 parts of single-end hydroxyl polybutadiene, 2 parts of N-methyl-N-hydroxyethyl p-toluidine, 4 parts of fumed silica, 3 parts of titanium dioxide and 45 parts of N-methylpyrrolidone were mixed and stirred at a speed of 1500 r / min for 5 minutes, and then ground for 30 minutes to obtain a hot melt adhesive;

[0084] B. The surface of a PET film having a thickness of 30 μm is subjected to corona treatment, and a hot melt adhesive is coated on the surface of the PET film after the corona treatment. After thermal curing, a hot melt adhesive layer having a thickness of 40 μm is formed to obtain a hot melt adhesive film for FFC wires.

[0085] Example 3

[0086] A. 38 parts of polyether TPU resin, 10 parts of double-terminated hydroxyl polybutadiene, 2 parts of N,N-dihydroxyethylaniline, 4 parts of fumed silica, 4 parts of titanium dioxide and 45 parts of acetylacetone were mixed and stirred at a speed of 1500 r / min for 5 minutes, and then ground for 30 minutes to obtain a hot melt adhesive;

[0087] B. The surface of a PET film having a thickness of 50 μm is subjected to corona treatment, and a hot melt adhesive is coated on the surface of the PET film after the corona treatment. After thermal curing, a hot melt adhesive layer having a thickness of 40 μm is formed to obtain a hot melt adhesive film for FFC wires.

[0088] Comparative Example 1

[0089] The preparation method and raw materials of Comparative Example 1 are the same as those of Example 1, except that phthalate resin is used instead of polycarbonate and dihydroxylated polybutadiene in the hot melt adhesive formula of Comparative Example 1; that is, calculated by weight, the hot melt adhesive includes the following raw materials: 50 parts of phthalate resin, 2 parts of 2,4,6-tris(dimethylaminomethyl)phenol, 4 parts of fumed silica, 4 parts of titanium dioxide and 45 parts of N,N-dimethylformamide.

[0090] Comparative Example 2

[0091] The preparation method and raw materials of Comparative Example 2 are the same as those of Example 1, except that polybutadiene polyol is not added to the hot melt adhesive formula in Comparative Example 2.

[0092] Comparative Example 3

[0093] The preparation method and raw materials of Comparative Example 3 are the same as those of Example 1, except that polycarbonate TPU is not added to the hot melt adhesive in Comparative Example 3.

[0094] The hot melt adhesive films prepared in the above examples and comparative examples were subjected to performance tests, and the specific test results are shown in Table 1 below:

[0095] Table 1 Test results of relevant properties of hot melt adhesive film

[0096]

[0097] It can be seen from the test results in Table 1 that compared with the hot melt adhesive film for FFC wires in Comparative Example 1 which uses polyester resin as the main resin, the hot melt adhesive film for FFC wires prepared by the present technical solution not only has excellent hydrolysis resistance and metal adhesion, but also has excellent acid resistance, low temperature resistance and flexibility resistance, thus meeting actual use requirements.

[0098] In Comparative Example 2, since no polybutadiene polyol was added, the hydrolysis resistance, metal adhesion, acid resistance, low temperature resistance and flexibility resistance of the hot melt adhesive film for FFC wire were reduced.

[0099] In Comparative Example 3, since no polycarbonate TPU was added, the hydrolysis resistance, metal adhesion, low temperature resistance and flexural resistance of the hot melt adhesive film for FFC wire were reduced.

[0100] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific implementations of the present invention without paying creative labor, and these methods will fall within the scope of protection of the present invention.

Claims

1. A hot melt adhesive film for FFC wire, characterized in that: It includes a substrate and a hot melt adhesive layer connected in sequence from bottom to top, wherein the hot melt adhesive layer is obtained by thermally curing the hot melt adhesive coated on the substrate; The hot melt adhesive comprises the following raw materials: TPU resin, polybutadiene polyol, curing reaction accelerator, filler and solvent; The TPU resin includes any one of a polyether TPU resin and a polycarbonate TPU resin.

2. A hot melt adhesive film for FFC wire according to claim 1, characterized in that: Calculated by weight, the hot melt adhesive includes the following raw materials: 35-40 parts of TPU resin, 5-15 parts of polybutadiene polyol, 1-2 parts of curing reaction accelerator, 6-10 parts of filler and 40-53 parts of solvent.

3. The hot melt adhesive film for FFC wire according to claim 1, characterized in that: The polybutadiene polyol is any one of single-terminal hydroxyl polybutadiene and double-terminal hydroxyl polybutadiene.

4. A hot melt adhesive film for FFC wire according to claim 3, characterized in that: The polybutadiene polyol is a double-terminal hydroxyl polybutadiene.

5. The hot melt adhesive film for FFC wire according to claim 2, characterized in that: The filler includes fumed silica and titanium dioxide; Calculated by weight, the hot melt adhesive includes the following raw materials: 35-40 parts of TPU resin, 5-15 parts of polybutadiene polyol, 1-2 parts of curing reaction accelerator, 3-5 parts of fumed silica, 3-5 parts of titanium dioxide and 40-53 parts of solvent.

6. The hot melt adhesive film for FFC wire according to claim 1, characterized in that: The curing reaction accelerator includes any one or more combinations of 2,4,6-tris(dimethylaminomethyl)phenol, N-methyl-N-hydroxyethyl-p-toluidine, N,N-dimethyl-p-toluidine, N,N-diethyl-p-toluidine, N,N-dihydroxyethylaniline, N,N-di(2-hydroxypropyl)aniline, triethylamine, triethanolamine and o-hydroxybenzyldimethylamine.

7. The hot melt adhesive film for FFC wire according to claim 1, characterized in that: The substrate is a PET film; The thickness of the PET film is 25-50 μm; the thickness of the hot melt adhesive layer is 21-80 μm.

8. A method for preparing a hot melt adhesive film for FFC wire, characterized in that: The method for preparing the hot melt adhesive film for FFC wire according to any one of claims 2 to 7 comprises the following steps: A. Mix the formulated amount of TPU resin, polybutadiene polyol, curing reaction accelerator, filler and solvent, stir them evenly, and grind them to obtain a hot melt adhesive; B. Coating hot melt adhesive on the surface of the substrate, forming a hot melt adhesive layer after thermal curing, and obtaining a hot melt adhesive film for FFC wire.

9. The method for preparing a hot melt adhesive film for FFC wire according to claim 8, characterized in that: In step A, the stirring speed is 800-2000 r / min, and the stirring time is 5-10 min; The grinding time of the grinding is 30 to 50 minutes.

10. The method for preparing a hot melt adhesive film for FFC wire according to claim 8, characterized in that: Step B specifically comprises: performing corona treatment on the surface of the substrate, coating the corona treated surface of the substrate with hot melt adhesive, forming a hot melt adhesive layer after thermal curing, and obtaining a hot melt adhesive film for FFC wires.

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