Resin composition and cover film

Abstract

The present application provides a kind of resin composition and covering film, the resin composition includes the following components by weight parts: carboxyl polyester resin 40-60 parts, epoxy resin 10-20 parts, thermoplastic polycaprolactone 10-20 parts, curing agent 5-10 parts;The melt index of the thermoplastic polycaprolactone at 160 DEG C is 5-8 dg / min.The resin composition of the present application can make the covering film have halogen-free flame retardancy, and the flame retardancy can reach V-0 level, has better peel strength, chemical resistance and heat resistance, can realize roll-to-roll roll pressing, is suitable for FPC roll-to-roll processing, compared with sheet processing, efficiency is higher, is more suitable for large size FPC production.

Description

Technical Field

[0001] This invention belongs to the technical field of cover film for flexible printed circuit boards, and relates to a resin composition and cover film. Background Technology

[0002] Flexible printed circuit boards (PCBs) are products with circuit patterns obtained by etching flexible copper-clad laminates as the substrate material using a subtractive etching process. PCBs are characterized by their lightness, thinness, shortness, and small size, and are widely used in electronic products.

[0003] Cover film is a film-like insulating material coated on one side of an insulating base film such as polyimide film or polyester film. It is an important component of flexible printed circuit boards (FPCs). Covering the circuit surface, it not only acts as a solder resist, protecting the circuit from dust, moisture, chemicals, and other forms of damage, but also provides reinforcement, improving the flexural strength of the FPC. Traditional cover films mainly use epoxy and acrylic adhesives. Both of these adhesives require high-pressure or pressure-transfer conditions to achieve effective bonding and circuit filling, which cannot meet the processing requirements of roll-to-roll pressing. Sheet lamination is not only inefficient but also cannot produce large-size FPCs. Currently, due to the limitations of the cover film adhesive layer in the rolling process, downstream FPCs cannot achieve roll-to-roll processing or be manufactured in larger sizes.

[0004] Therefore, developing a roll-to-roll resin composition for use in cover films is of great significance for improving FPC production efficiency and producing large-size FPCs. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a resin composition and a cover film, wherein the resin composition enables the cover film to have halogen-free flame retardancy, achieving a flame retardancy rating of V-0, and possessing good peel strength, chemical resistance, and heat resistance, and enabling roll-to-roll rolling.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In one aspect, the present invention provides a resin composition comprising the following components in parts by weight:

[0008] 40-60 parts of carboxylated polyester resin, 10-20 parts of epoxy resin, 10-20 parts of thermoplastic polycaprolactone, and 5-10 parts of curing agent;

[0009] In the resin composition of the present invention, carboxylated polyester resin is used as the main resin, which gives the resin composition good flexibility and adhesion; the introduction of epoxy resin into the composition can increase the crosslinking density of the system, giving the resin composition excellent heat resistance and controllable glue overflow; thermoplastic polycaprolactone has good high-temperature fluidity, which can give the resin composition good fluidity and ensure that the prepared cover film has excellent line filling properties under rolling processing conditions.

[0010] In this invention, the melt flow index of the thermoplastic polycaprolactone at 160°C is 5-8 dg / min (e.g., 5 dg / min, 6 dg / min, 7 dg / min, or 8 dg / min), which enables the resin composition of this invention to have moderate fluidity. If the melt flow index is below 5 dg / min, the melt flowability of the resin composition is insufficient, resulting in poor circuit filling during cover film rolling; if the melt flow index is above 8 dg / min, the melt flowability of the resin composition is too high, resulting in excessive glue overflow and pad contamination during cover film rolling. The melt flow index of this invention is determined according to the standard ASTM-D1238.

[0011] In the resin composition of the present invention, the amount of the carboxylated polyester resin may be 40 parts by weight, 43 parts by weight, 45 parts by weight, 48 parts by weight, 50 parts by weight, 53 parts by weight, 55 parts by weight, 58 parts by weight, or 60 parts by weight; the amount of the epoxy resin may be 10 parts by weight, 12 parts by weight, 15 parts by weight, 18 parts by weight, or 20 parts by weight; the amount of the thermoplastic polycaprolactone may be 10 parts by weight, 12 parts by weight, 15 parts by weight, 18 parts by weight, or 20 parts by weight; and the amount of the curing agent may be 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, or 10 parts by weight.

[0012] The "parts" and "parts by weight" used in this invention are calculated based on solid content and do not include solvents, dispersants, etc.

[0013] In this invention, the carboxyl polyester resin has an acid value of 10-20 mgKOH / g (e.g., 10 mgKOH / g, 12 mgKOH / g, 15 mgKOH / g, 18 mgKOH / g, or 20 mgKOH / g) and a glass transition temperature of 10-30℃ (e.g., 10℃, 13℃, 15℃, 18℃, 20℃, 23℃, 25℃, 28℃, or 30℃). If the acid value of the carboxyl polyester resin is too low, its reactivity with the epoxy resin is insufficient, leading to poor compatibility of the resin composition, decreased heat resistance, and reduced peel strength. If the acid value of the carboxyl polyester resin is too high, a large number of carboxyl groups remain after the resin composition is cured, resulting in poor chemical resistance of the cover film. If the glass transition temperature of the carboxyl polyester resin is too low, the heat resistance of the resin composition is insufficient; if the glass transition temperature of the carboxyl polyester resin is too high, the flexibility of the resin composition is insufficient, and the peel strength is reduced.

[0014] In this invention, the number average molecular weight of the carboxylated polyester resin is 10,000-20,000, for example, 10,000, 12,000, 15,000, 18,000, or 20,000. In this invention, if the molecular weight of the carboxylated polyester resin is too low, the film-forming properties and cohesive strength are insufficient, resulting in poor peel strength and heat resistance; if the molecular weight of the carboxylated polyester resin is too high, the flowability of the resin composition deteriorates, resulting in poor conformability and peel strength.

[0015] The number-average molecular weight of the present invention can be determined by gel permeation chromatography based on polystyrene calibration, referring to GB / T 21863-2008.

[0016] Preferably, the epoxy resin is a bifunctional epoxy resin or a multifunctional epoxy resin. In this invention, the multifunctional epoxy resin refers to an epoxy resin with three or more functionalities.

[0017] Preferably, the epoxy equivalent of the epoxy resin is 100-600 g / eq, for example 100 g / eq, 150 g / eq, 180 g / eq, 200 g / eq, 250 g / eq, 300 g / eq, 350 g / eq, 400 g / eq, 450 g / eq, 500 g / eq, 550 g / eq or 600 g / eq.

[0018] Preferably, the epoxy resin is selected from one or a combination of at least two of bisphenol A epoxy resin, bisphenol F epoxy resin, linear phenolic epoxy resin, bisphenol A phenolic epoxy resin, or o-cresol phenolic epoxy resin.

[0019] Preferably, the curing agent is an amine curing agent or an acid anhydride curing agent.

[0020] Preferably, the amine curing agent is any one or a combination of at least two of dicyandiamide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, or 4,4'-diaminodiphenylmethane;

[0021] Preferably, the anhydride curing agent is any one or a combination of at least two of phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride or methyltetrahydrophthalic anhydride.

[0022] Preferably, the resin composition further includes 10-30 parts of flame retardant, wherein the amount of flame retardant can be 10 parts by weight, 12 parts by weight, 15 parts by weight, 18 parts by weight, 20 parts by weight, 22 parts by weight, 25 parts by weight, 28 parts by weight, or 30 parts by weight.

[0023] Preferably, the flame retardant is a phosphorus-containing flame retardant.

[0024] Preferably, the resin composition further includes 0.1-1 parts of an antioxidant, wherein the amount of antioxidant can be 0.1 parts by weight, 0.3 parts by weight, 0.5 parts by weight, 0.8 parts by weight, or 1 part by weight.

[0025] Preferably, the antioxidant is a hindered phenolic antioxidant or a phosphate ester antioxidant.

[0026] On the other hand, the present invention provides a resin composition liquid obtained by dissolving or dispersing the resin composition as described above in an organic solvent.

[0027] Preferably, the organic solvent is selected from one or a combination of at least two of acetone, butanone, cyclohexanone, ethylene glycol monomethyl ether, propylene glycol methyl ether, propylene glycol methyl ether acetate, ethyl acetate, butyl acetate, etc.

[0028] On the other hand, the present invention provides a cover film comprising an insulating base film and an adhesive layer coated on the insulating base film, the adhesive layer being formed from the resin composition described above.

[0029] Preferably, the insulating base film is selected from one of polyimide film (PI), polyethylene terephthalate film (PET), or polyethylene naphthalate film (PEN). PI film has excellent heat resistance and dimensional stability, and PI film is preferred.

[0030] In this invention, the covering film can be prepared using the following method:

[0031] The components of the resin composition described above are mixed with an organic solvent. Using a ball mill, pot mill, sand mill, or similar equipment, and in conjunction with a high-shear stirring and dispersing device, the organic solid components and added inorganic solid components of the resin composition are mixed together with the organic solvent to prepare a resin composition liquid. This resin composition liquid is then coated onto an insulating substrate using a coating device. The insulating substrate coated with the resin composition liquid is then passed through an online drying oven and heated at 80–160°C for 2–10 minutes to remove the organic solvent. The substrate is then wound up to obtain the cover film.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The resin composition of the present invention enables the cover film to have halogen-free flame retardancy, reaching a flame retardancy rating of V-0, and has good peel strength, chemical resistance and heat resistance. It can realize roll-to-roll rolling, is suitable for roll-to-roll processing of FPC, and is more efficient than sheet processing, making it more suitable for the production of large-size FPC. Detailed Implementation

[0034] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0035] The source information of the raw materials used in the examples is as follows:

[0036] (1) Carboxylated polyester resin

[0037] TOYOBO Japan's BX-39SS has an acid value of 17 mgKOH / g, a glass transition temperature of 15℃, and a number-average molecular weight of 16,000.

[0038] Suzhou Hanhai Technology Co., Ltd.'s AL148 has an acid value of 18 mgKOH / g, a glass transition temperature of 19℃, and a number-average molecular weight of 15000.

[0039] Suzhou Hanhai Technology Co., Ltd.'s AL260 has an acid value of 3 mgKOH / g, a glass transition temperature of 20℃, and a number-average molecular weight of 20,000.

[0040] HH-2782 from Qingtian Materials Technology Co., Ltd., has an acid value of 29 mg KOH / g and a glass transition temperature of 60℃.

[0041] TOYOBO Corporation of Japan's ST5810 has an acid value of 18 mgKOH / g, a glass transition temperature of 39℃, and a number-average molecular weight of 10,000.

[0042] TOYOBO GK180 from Japan has an acid value of 5 mg KOH / g, a glass transition temperature of 0℃, and a number-average molecular weight of 10,000.

[0043] Suzhou Hanhai Technology Co., Ltd.'s AL177 has an acid value of 3 mgKOH / g, a glass transition temperature of 12℃, and a number-average molecular weight of 27,000.

[0044] Suzhou Hanhai Technology Co., Ltd.'s AL120 has an acid value of 3 mgKOH / g, a glass transition temperature of 12℃, and a number-average molecular weight of 7000.

[0045] (2) Thermoplastic polycaprolactone

[0046] Perstor's CAPA 6500 has a melt index of 7 dg / min.

[0047] Shenzhen Guanghua Weiye ESUN1000C, melt flow index 6 dg / min;

[0048] Perstor's CAPA 6800 has a melt index of 3 dg / min.

[0049] Perstor's CAPA 6430 has a melt index of 13 dg / min.

[0050] (3) Flame retardant

[0051] Clariant Chemicals of Switzerland, Exolit OP-935.

[0052] (4) Antioxidants

[0053] Antioxidants 1010, 168, 1098, 1790, 1035.

[0054] Example 1

[0055] A resin composition, by weight, comprises: 40 parts of carboxylated polyester resin BX-39SS, 10 parts of bisphenol A epoxy resin, 10 parts of thermoplastic polycaprolactone capa6500, 5 parts of dicyandiamide, 10 parts of flame retardant Exolit OP-935, and 0.1 parts of antioxidant 1010.

[0056] The above-mentioned components and the organic solvent methyl ethyl ketone are emulsified, dispersed and mixed to prepare a resin composition liquid with a solid content of 30 wt%. The resin composition liquid is then coated onto a PI film using a coating device.

[0057] The PI film coated with the resin composition solution is then passed through an online drying oven and heated at 80°C for 10 minutes to remove the organic solvent. The film is then wound up to obtain the cover film.

[0058] Example 2

[0059] A resin composition, by weight, comprises: 60 parts of carboxylated polyester resin AL148, 20 parts of linear phenolic epoxy resin, 20 parts of thermoplastic polycaprolactone ESUN1000C, 10 parts of phthalic anhydride, 30 parts of flame retardant Exolit OP-935, and 1 part of antioxidant 168.

[0060] The above-mentioned components and the organic solvent cyclohexanone are dispersed and mixed by sand milling to prepare a resin composition liquid with a solid content of 60 wt%. The resin composition liquid is then coated onto a PI film using a coating device.

[0061] The PI film coated with the resin composition solution is then passed through an online drying oven and heated at 160°C for 2 minutes to remove the organic solvent. The film is then wound up to obtain the cover film.

[0062] Example 3

[0063] A resin composition, by weight, comprises: 40 parts of carboxylated polyester resin AL260, 10 parts of bisphenol A epoxy resin, 10 parts of thermoplastic polycaprolactone capa6500, 5 parts of dicyandiamide, 10 parts of flame retardant Exolit OP-935, and 1.1 parts of antioxidant 10100.

[0064] The above-mentioned components and the organic solvent methyl ethyl ketone are emulsified, dispersed and mixed to prepare a resin composition liquid with a solid content of 30 wt%. The resin composition liquid is then coated onto a PI film using a coating device.

[0065] The PI film coated with the resin composition solution is then passed through an online drying oven and heated at 80°C for 10 minutes to remove the organic solvent. The film is then wound up to obtain the cover film.

[0066] Example 4

[0067] A resin composition, by weight, comprises: 40 parts of carboxylated polyester resin HH-2782, 10 parts of bisphenol A epoxy resin, 10 parts of thermoplastic polycaprolactone capa6500, 5 parts of dicyandiamide, 10 parts of flame retardant Exolit OP-935, and 0.1 parts of antioxidant 1010.

[0068] The above-mentioned components and the organic solvent methyl ethyl ketone are emulsified, dispersed and mixed to prepare a resin composition liquid with a solid content of 30 wt%. The resin composition liquid is then coated onto a PI film using a coating device.

[0069] The PI film coated with the resin composition solution is then passed through an online drying oven and heated at 80°C for 10 minutes to remove the organic solvent. The film is then wound up to obtain the cover film.

[0070] Example 5

[0071] A resin composition, by weight, comprises: 40 parts of carboxylated polyester resin ST5810, 10 parts of bisphenol A epoxy resin, 10 parts of thermoplastic polycaprolactone capa6500, 5 parts of dicyandiamide, 10 parts of flame retardant Exolit OP-935, and 0.1 parts of antioxidant 1010.

[0072] The above-mentioned components and the organic solvent methyl ethyl ketone are emulsified, dispersed and mixed to prepare a resin composition liquid with a solid content of 30 wt%. The resin composition liquid is then coated onto a PI film using a coating device.

[0073] The PI film coated with the resin composition solution is then passed through an online drying oven and heated at 80°C for 10 minutes to remove the organic solvent. The film is then wound up to obtain the cover film.

[0074] Example 6

[0075] A resin composition, by weight, comprises: 40 parts of carboxylated polyester resin GK180, 10 parts of bisphenol A epoxy resin, 10 parts of thermoplastic polycaprolactone capa6500, 5 parts of dicyandiamide, 10 parts of flame retardant Exolit OP-935, and 1.1 parts of antioxidant 10100.

[0076] The above-mentioned components and the organic solvent methyl ethyl ketone are emulsified, dispersed and mixed to prepare a resin composition liquid with a solid content of 30 wt%. The resin composition liquid is then coated onto a PI film using a coating device.

[0077] The PI film coated with the resin composition solution is then passed through an online drying oven and heated at 80°C for 10 minutes to remove the organic solvent. The film is then wound up to obtain the cover film.

[0078] Example 7

[0079] A resin composition, by weight, comprises: 40 parts of carboxylated polyester resin AL177, 10 parts of bisphenol A epoxy resin, 10 parts of thermoplastic polycaprolactone capa6500, 5 parts of dicyandiamide, 10 parts of flame retardant Exolit OP-935, and 1.1 parts of antioxidant 10100.

[0080] The above-mentioned components and the organic solvent methyl ethyl ketone are emulsified, dispersed and mixed to prepare a resin composition liquid with a solid content of 30 wt%. The resin composition liquid is then coated onto a PI film using a coating device.

[0081] The PI film coated with the resin composition solution is then passed through an online drying oven and heated at 80°C for 10 minutes to remove the organic solvent. The film is then wound up to obtain the cover film.

[0082] Example 8

[0083] A resin composition, by weight, comprises: 40 parts of carboxylated polyester resin AL120, 10 parts of bisphenol A epoxy resin, 10 parts of thermoplastic polycaprolactone capa6500, 5 parts of dicyandiamide, 10 parts of flame retardant Exolit OP-935, and 1.1 parts of antioxidant 10100.

[0084] The above-mentioned components and the organic solvent methyl ethyl ketone are emulsified, dispersed and mixed to prepare a resin composition liquid with a solid content of 30 wt%. The resin composition liquid is then coated onto a PI film using a coating device.

[0085] The PI film coated with the resin composition solution is then passed through an online drying oven and heated at 80°C for 10 minutes to remove the organic solvent. The film is then wound up to obtain the cover film.

[0086] Example 9

[0087] A resin composition, by weight, comprises: 40 parts of carboxylated polyester resin BX-39SS, 10 parts of bisphenol A epoxy resin, 10 parts of thermoplastic polycaprolactone capa6500, 5 parts of isocyanate (TPAB80E, blocked isocyanate resin, HDI type, Asahi Kasei, Japan), 10 parts of flame retardant Exolit OP-935, and 0.1 parts of antioxidant 1010.

[0088] The above-mentioned components and the organic solvent methyl ethyl ketone are emulsified, dispersed and mixed to prepare a resin composition liquid with a solid content of 30 wt%. The resin composition liquid is then coated onto a PI film using a coating device.

[0089] The PI film coated with the resin composition solution is then passed through an online drying oven and heated at 80°C for 10 minutes to remove the organic solvent. The film is then wound up to obtain the cover film.

[0090] Example 10

[0091] A resin composition, by weight, comprises: 40 parts of carboxylated polyester resin BX-39SS, 10 parts of bisphenol A epoxy resin, 10 parts of thermoplastic polycaprolactone capa6500, 5 parts of isocyanate (C-HXR, isocyanate resin, HDI type, TOSOH Japan), 10 parts of flame retardant Exolit OP-935, and 0.1 parts of antioxidant 1010.

[0092] The above-mentioned components and the organic solvent methyl ethyl ketone are emulsified, dispersed and mixed to prepare a resin composition liquid with a solid content of 30 wt%. The resin composition liquid is then coated onto a PI film using a coating device.

[0093] The PI film coated with the resin composition solution is then passed through an online drying oven and heated at 80°C for 10 minutes to remove the organic solvent. The film is then wound up to obtain the cover film.

[0094] Comparative Example 1

[0095] Except for the absence of thermoplastic polycaprolactone, it is the same as in Example 1.

[0096] Comparative Example 2

[0097] A resin composition, by weight, comprises: 40 parts of carboxylated polyester resin BX-39SS, 10 parts of bisphenol A epoxy resin, 10 parts of petroleum resin (Mitsui Chemicals FTR-6100), 5 parts of dicyandiamide, 10 parts of flame retardant Exolit OP-935, and 0.1 parts of antioxidant 1010.

[0098] The above-mentioned components and the organic solvent methyl ethyl ketone are emulsified, dispersed and mixed to prepare a resin composition liquid with a solid content of 30 wt%. The resin composition liquid is then coated onto a PI film using a coating device.

[0099] The PI film coated with the resin composition solution is then passed through an online drying oven and heated at 80°C for 10 minutes to remove the organic solvent. The film is then wound up to obtain the cover film.

[0100] Comparative Example 3

[0101] A resin composition, by weight, comprises: 40 parts of carboxylated polyester resin BX-39SS, 10 parts of bisphenol A epoxy resin, 10 parts of terpene resin (CAS No. 9003-74-1), 5 parts of dicyandiamide, 10 parts of flame retardant Exolit OP-935, and 0.1 parts of antioxidant 1010.

[0102] The above-mentioned components and the organic solvent methyl ethyl ketone are emulsified, dispersed and mixed to prepare a resin composition liquid with a solid content of 30 wt%. The resin composition liquid is then coated onto a PI film using a coating device.

[0103] The PI film coated with the resin composition solution is then passed through an online drying oven and heated at 80°C for 10 minutes to remove the organic solvent. The film is then wound up to obtain the cover film.

[0104] Comparative Example 4

[0105] A resin composition, by weight, comprises: 40 parts of carboxylated polyester resin BX-39SS, 10 parts of bisphenol A epoxy resin, 10 parts of rosin resin (CAS No. 85026-55-7), 5 parts of dicyandiamide, 10 parts of flame retardant Exolit OP-935, and 0.1 parts of antioxidant 1010.

[0106] The above-mentioned components and the organic solvent methyl ethyl ketone are emulsified, dispersed and mixed to prepare a resin composition liquid with a solid content of 30 wt%. The resin composition liquid is then coated onto a PI film using a coating device.

[0107] The PI film coated with the resin composition solution is then passed through an online drying oven and heated at 80°C for 10 minutes to remove the organic solvent. The film is then wound up to obtain the cover film.

[0108] Comparative Example 5

[0109] A resin composition, by weight, comprises: 40 parts of carboxylated polyester resin BX-39SS, 10 parts of bisphenol A epoxy resin, 10 parts of thermoplastic polycaprolactone capa6430, 5 parts of dicyandiamide, 10 parts of flame retardant Exolit OP-935, and 0.1 parts of antioxidant 1010.

[0110] The above-mentioned components and the organic solvent methyl ethyl ketone are emulsified, dispersed and mixed to prepare a resin composition liquid with a solid content of 30 wt%. The resin composition liquid is then coated onto a PI film using a coating device.

[0111] The PI film coated with the resin composition solution is then passed through an online drying oven and heated at 80°C for 10 minutes to remove the organic solvent. The film is then wound up to obtain the cover film.

[0112] Comparative Example 6

[0113] A resin composition, by weight, comprises: 40 parts of carboxylated polyester resin BX-39SS, 10 parts of bisphenol A epoxy resin, 10 parts of thermoplastic polycaprolactone capa6800, 5 parts of dicyandiamide, 10 parts of flame retardant Exolit OP-935, and 0.1 parts of antioxidant 1010.

[0114] The above-mentioned components and the organic solvent methyl ethyl ketone are emulsified, dispersed and mixed to prepare a resin composition liquid with a solid content of 30 wt%. The resin composition liquid is then coated onto a PI film using a coating device.

[0115] The PI film coated with the resin composition solution is then passed through an online drying oven and heated at 80°C for 10 minutes to remove the organic solvent. The film is then wound up to obtain the cover film.

[0116] The adhesive layer thickness was uniformly set at 35 μm, and the performance of the cover films prepared in the examples and comparative examples was evaluated by parallel comparison. The specific test methods are as follows:

[0117] (1) Peel strength: After the cover film was rolled and bonded to the smooth surface of 18μm rolled copper foil, it was cured at 160℃ for 1 hour and tested according to IPC-TM-650 2.4.9. Rolling temperature 150℃, linear speed 5m / min, pressure 0.5MPa.

[0118] (2) Coverability: Roll the cover film onto the circuit and observe whether there are air bubbles between the lines. If there are air bubbles, the coverability fails; if there are no air bubbles, the coverability passes. Rolling temperature: 150℃, line speed: 5m / min, pressure: 0.5MPa; copper thickness of the circuit: 50μm, line width: 100μm, line spacing: 100μm.

[0119] (3) Excess adhesive: Tested according to IPC-TM-650 2.3.17.1 method, measuring the annular spacing of excess adhesive along the circumference of the punched hole on the sample.

[0120] (4) Heat resistance limit temperature: After the cover film is rolled and bonded to the smooth surface of 18μm rolled copper foil, it is cured at 160℃ for 1 hour. Rolling temperature: 150℃, linear speed: 5m / min, pressure: 0.5MPa.

[0121] The cured sample was cut into 5cm×5cm pieces and immersed in tin baths at 288℃, 300℃, 310℃, 320℃, 330℃, 340℃ and 350℃ for 5 minutes. After that, it was taken out and observed whether there were stratified bubbles. The highest test temperature without stratified bubbles was taken as the heat resistance limit temperature.

[0122] (5) Chemical resistance: After the cover film is rolled and bonded to the smooth surface of 18μm rolled copper foil, it is cured at 160℃ for 1 hour and tested according to IPC-TM-650 2.3.2A method.

[0123] (6) Flame retardancy: tested according to UL standards.

[0124] The performance test results are shown in Table 1.

[0125] Table 1

[0126] Test Project Peel strength N / mm Coverage Glue overflow / mm Heat resistance limit temperature / °C Chemical resistance / % Flame retardancy Example 1 1.84 pass 0.212 350 100 V-0 Example 2 1.96 pass 0.208 350 100 V-0 Example 3 1.15 pass 0.231 340 100 V-0 Example 4 1.68 pass 0.194 350 93 V-0 Example 5 1.21 pass 0.219 350 100 V-0 Example 6 1.85 pass 0.218 330 100 V-0 Example 7 1.05 Not approved 0.169 350 100 V-0 Example 8 1.19 pass 0.229 330 100 V-0 Example 9 1.45 pass 0.227 350 100 V-0 Example 10 0.91 Not approved 0.051 350 100 V-1 Comparative Example 1 0.31 Not approved 0.092 ＜288 100 V-0 Comparative Example 2 0.52 Not approved 0.131 288 89 V-0 Comparative Example 3 0.49 Not approved 0.101 288 83 V-0 Comparative Example 4 0.59 Not approved 0.121 288 94 V-0 Comparative Example 5 1.41 Not approved 0.451 320 95 V-0 Comparative Example 6 0.84 Not approved 0.142 330 96 V-0

[0127] As can be seen from the data in Table 1, the resin composition provided in Examples 1-2 of the present invention and the insulating film prepared therefrom have a moderate amount of adhesive overflow, excellent conformability, heat resistance, chemical resistance and flame retardancy, and a peel strength ≥1.84N / mm.

[0128] When the acid value of the carboxylated polyester resin in Examples 3-4 is not within the preferred range, the peel strength, heat resistance, or chemical resistance of the prepared cover film are not as good as those in Example 1; when the glass transition temperature of the carboxylated polyester resin in Examples 5-6 is not within the preferred range, the peel strength or heat resistance of the prepared cover film are not as good as those in Example 1; when the number average molecular weight of the carboxylated polyester resin in Examples 7-8 is not within the preferred range, the conformability, heat resistance, or peel strength of the prepared cover film are not as good as those in Example 1.

[0129] Compared to Example 1, Examples 9-10, which use blocked isocyanate curing agents and isocyanate curing agents, show that the peel strength of the cover films prepared is not as good as that of Example 1.

[0130] Compared to Example 1, Comparative Example 1 does not contain thermoplastic polycaprolactone, resulting in a cover film prepared therewith having poor conformability, peel strength and heat resistance compared to Example 1. The adhesive layer has insufficient fluidity and the amount of adhesive overflow is significantly lower.

[0131] Compared to Example 1, Comparative Examples 2-4 used petroleum resin, terpene resin, and rosin resin to replace thermoplastic polycaprolactone, respectively, resulting in coatings prepared with these alternatives exhibiting inferior conformability, peel strength, heat resistance, and chemical resistance compared to Example 1.

[0132] When the melt index of the thermoplastic polycaprolactone in Comparative Examples 5-6 is not within the range of the present invention, the conformability, heat resistance, chemical resistance and peel strength of the cover film prepared by it are not as good as those in Example 1.

[0133] The applicant declares that the resin composition and covering film of the present invention are illustrated through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A resin composition, characterized in that, The resin composition comprises the following components in parts by weight: 40-60 parts of carboxylated polyester resin, 10-20 parts of epoxy resin, 10-20 parts of thermoplastic polycaprolactone, and 5-10 parts of curing agent; The thermoplastic polycaprolactone has a melt index of 6-8 dg / min at 160°C; The carboxylated polyester resin has an acid value of 10-20 mgKOH / g, a glass transition temperature of 10-30℃, and a number-average molecular weight of 10000-20000. The curing agent is an amine curing agent or an acid anhydride curing agent; The resin composition further includes 10-30 parts of a flame retardant, wherein the flame retardant is a phosphorus-containing flame retardant.

2. The resin composition according to claim 1, characterized in that, The epoxy resin is a bifunctional epoxy resin or a multifunctional epoxy resin.

3. The resin composition according to claim 1, characterized in that, The epoxy equivalent of the epoxy resin is 100-600 g / eq.

4. The resin composition according to claim 1, characterized in that, The epoxy resin is selected from one or a combination of at least two of bisphenol A epoxy resin, bisphenol F epoxy resin, linear phenolic epoxy resin, bisphenol A phenolic epoxy resin, or o-cresol phenolic epoxy resin.

5. The resin composition according to claim 1, characterized in that, The amine curing agent is any one or a combination of at least two of dicyandiamide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, or 4,4'-diaminodiphenylmethane.

6. The resin composition according to claim 1, characterized in that, The anhydride curing agent is any one or a combination of at least two of phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride or methyltetrahydrophthalic anhydride.

7. The resin composition according to claim 1, characterized in that, The resin composition further includes 0.1-1 parts of antioxidant.

8. The resin composition according to claim 7, characterized in that, The antioxidant is a hindered phenolic antioxidant or a phosphate ester antioxidant.

9. A resin composition liquid, characterized in that, It is obtained by dissolving or dispersing the resin composition as described in any one of claims 1-8 in an organic solvent.

10. The resin composition liquid according to claim 9, characterized in that, The organic solvent is selected from one or a combination of at least two of acetone, butanone, cyclohexanone, ethylene glycol monomethyl ether, propylene glycol methyl ether, propylene glycol methyl ether acetate, ethyl acetate, and butyl acetate.

11. A covering film, characterized in that, The cover film includes an insulating base film and an adhesive layer coated on the insulating base film, the adhesive layer being formed from a resin composition as described in any one of claims 1-8.

12. The covering film according to claim 11, characterized in that, The insulating base film is selected from one of polyimide film, polyethylene terephthalate film, or polyethylene naphthalate film.