Single-component medium-low temperature thermocuring FPC (Flexible Printed Circuit) encapsulating adhesive and preparation method thereof

Abstract

The invention provides a single-component medium-low temperature thermocuring FPC (Flexible Printed Circuit) encapsulating adhesive and a preparation method thereof. The encapsulating adhesive is prepared from the following components in parts by weight: 20 to 50 parts of acrylate oligomer, 20 to 60 parts of reactive diluent, 0.5 to 5 parts of thermal initiator and 1 to 10 parts of rheological additive, wherein the reactive diluent is composed of a first reactive diluent and a second reactive diluent, the first reactive diluent comprises ACMO, and the second reactive diluent comprises at least one of IBOA and CTFA; the thermal initiator is prepared from at least one of azobisisoheptonitrile, azobisisobutyronitrile, benzoyl peroxide and dilauroyl peroxide. The encapsulating compound prepared by the preparation method disclosed by the invention has high efficiency, construction convenience and low energy consumption while ensuring mechanical properties.

Description

One-component medium-low temperature thermosetting FPC encapsulating adhesive and its preparation method Technical Field

[0001] This invention belongs to the field of adhesive technology, specifically relating to a single-component, low-temperature thermosetting FPC encapsulating adhesive and its preparation method. Background Technology

[0002] Encapsulating adhesive is a protective coating applied to electronic components such as capacitors, resistors, and diodes on circuit boards. Its function is to isolate sensitive electronic components from harsh environments, protecting circuits and components from environmental factors such as moisture, pollutants, corrosion, stress, impact, mechanical vibration, and thermal cycling.

[0003] Currently, traditional thermosetting two-component encapsulating adhesives used in this field suffer from numerous problems, including inconvenient application, low efficiency, and VOC emissions. While single-component thermosetting encapsulating adhesives on the market offer high efficiency and ease of application, they generally require high curing temperatures (basically above 150°C), resulting in high energy consumption. Emerging UV-curing and moisture-curing dual-curing encapsulating adhesives, however, suffer from high prices, insufficient initial curing strength, and high equipment investment. Therefore, the demand for low-energy, high-efficiency encapsulating adhesive products is becoming increasingly apparent. Summary of the Invention

[0004] In view of this, the present invention provides a single-component, low-temperature thermosetting FPC encapsulating adhesive and its preparation method, which can ensure mechanical properties while enabling the encapsulating adhesive to have high efficiency, convenient construction and low energy consumption.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a single-component, low-temperature thermosetting FPC encapsulating adhesive, comprising, by weight, the following components: 20-50 parts of acrylate oligomer, 20-60 parts of reactive diluent, 0.5-5 parts of thermal initiator, and 1-10 parts of rheology modifier; wherein the reactive diluent is composed of a first reactive diluent and a second reactive diluent, the first reactive diluent comprising ACMO (acryloylmorpholine), and the second reactive diluent comprising at least one of IBOA (isoborneol acrylate) and CTFA (cyclotrimethylolpropane methyl acetal acrylate); the thermal initiator comprising at least one of azobisisobutyronitrile, azobisisobutyronitrile, benzoyl peroxide, and dilauryl peroxide.

[0006] It should be noted that the above-mentioned reactive diluent has a fast curing speed and strong dilution properties; the above-mentioned thermal initiator can be matched with medium and low temperature ranges, and can also undergo redox reaction with ACMO under heating to achieve a rapid curing effect.

[0007] Preferably, the acrylate oligomer includes at least one of difunctional polyurethane acrylate resin and fatty acid-modified epoxy acrylate resin. It should be noted that using the above-mentioned acrylate oligomer can ensure good adhesion to the substrate while giving the cured film good flexibility, thus avoiding the risk of low-temperature cracking.

[0008] Preferably, the rheology modifier includes at least one of fumed silica, organobentonite, and polyamide wax. It should be noted that using the above-mentioned rheology modifier ensures good workability, and a suitable thixotropic index ensures good encapsulation.

[0009] Secondly, the present invention also provides a method for preparing a single-component, low-temperature thermosetting FPC encapsulating adhesive, comprising the following steps: S1, adding an acrylate oligomer and an active diluent to a reaction vessel and stirring to obtain a first mixture; S2, adding a rheology modifier to the first mixture and stirring to obtain a second mixture; S3, adding a thermal initiator to the second mixture and stirring to obtain a single-component, low-temperature thermosetting FPC encapsulating adhesive.

[0010] Preferably, in step S1, the stirring speed is 300~600 r / min and the stirring time is 10~30 min.

[0011] Preferably, in step S2, the stirring speed is 1500~2500 r / min, and the stirring time is 20~30 min. It should be noted that the stirring speed and time being within the above range ensure that the rheology modifier is fully dispersed to obtain the desired thixotropic properties.

[0012] Preferably, in step S3, the stirring speed is 800~1200 r / min and the stirring time is 10~20 min.

[0013] Preferably, in step S3, the stirring temperature is 10~20 °C. It should be noted that maintaining the stirring temperature within this range helps prevent premature decomposition and failure of the thermal initiator.

[0014] Preferably, in step S3, a thermal initiator is added to the second mixture, and after stirring, the mixture is filtered to obtain a single-component medium-low temperature thermosetting FPC encapsulating adhesive.

[0015] Preferably, in step S3, the filtration uses a filter bag, wherein the filter bag has a mesh size of 500 mesh.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The single-component medium-low temperature thermosetting FPC encapsulating adhesive provided by the present invention, by using a suitable thermal initiator and active diluent, can effectively reduce the curing temperature and shorten the curing time, achieve medium-low temperature thermosetting, improve curing efficiency and reduce energy consumption; at the same time, by using this thermosetting method of acrylate oligomers, the encapsulating adhesive has high efficiency, convenient construction and low energy consumption while ensuring mechanical properties. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention. Unless otherwise specified, the technical means used in the following embodiments are all conventional means well known to those skilled in the art, and all reagents and consumables are commercially available products.

[0018] Example 1 This example provides a single-component, low-temperature thermosetting FPC encapsulating adhesive, which is composed of the following components in parts by weight: 40 parts of acrylate oligomer, 51 parts of reactive diluent, 3 parts of thermal initiator and 6 parts of rheology modifier; wherein, the acrylate oligomer is composed of difunctional polyurethane acrylate and fatty acid modified epoxy acrylate resin in a weight ratio of 2:1, the reactive diluent is composed of IBOA and ACMO in a weight ratio of 1:1, the thermal initiator is benzoyl peroxide, and the rheology modifier is fumed silica; the specific preparation steps of the single-component, low-temperature thermosetting FPC encapsulating adhesive are as follows: (1) Add the difunctional polyurethane acrylate, fatty acid modified epoxy acrylate resin, IBOA and ACMO to a mixing tank, stir evenly to obtain a first mixture, wherein the stirring speed is 500 r / min and the stirring time is 10 min; (2) Add fumed silica to the first mixture, stir evenly to obtain a second mixture, wherein the stirring speed is 2000 r / min. (3) Add benzoyl peroxide to the second mixture, stir evenly, filter with a 150-mesh filter bag to obtain a single-component medium-low temperature thermosetting FPC encapsulating adhesive, wherein the stirring speed is 1000 r / min, the temperature inside the reactor is controlled at 10℃ during stirring, and the stirring time is 10 min.

[0019] The prepared encapsulating adhesive is applied on a dispensing machine, with the application temperature controlled at 25~35 ℃. It can be fully cured in 20 minutes at 95 ℃.

[0020] Example 2 This example provides a single-component, low-temperature thermosetting FPC encapsulating adhesive, which consists of the following components in parts by weight: 36 parts of acrylate oligomer, 55 parts of reactive diluent, 4 parts of thermal initiator and 6 parts of rheology modifier; wherein, the acrylate oligomer is a difunctional polyurethane acrylate, the reactive diluent is composed of CTFA and ACMO in a weight ratio of 1:2, the thermal initiator is composed of azobisisobutyronitrile and dilauryl peroxide in a weight ratio of 3:1, and the rheology modifier is organobentonite; the specific preparation steps of the single-component, low-temperature thermosetting FPC encapsulating adhesive are as follows: (1) Add the difunctional polyurethane acrylate, CTFA and ACMO to a mixing tank and stir evenly to obtain a first mixture, wherein the stirring speed is 500 r / min and the stirring time is 10 min; (2) Add organobentonite to the first mixture and stir evenly to obtain a second mixture, wherein the stirring speed is 2000 r / min and the stirring time is 20 min. min; (3) Add azobisisobutyronitrile and dilauryl peroxide to the second mixture, stir evenly, filter with a 150-mesh filter bag to obtain a single-component medium-low temperature thermosetting FPC encapsulating adhesive, wherein the stirring speed is 1000 r / min, the temperature inside the reactor is controlled at 10 ℃ during stirring, and the stirring time is 10 min.

[0021] The prepared encapsulating adhesive is applied on a dispensing machine, with the application temperature controlled at 25~35 ℃. It can be fully cured in 20 minutes at 100 ℃.

[0022] Example 3 This example provides a single-component, low-temperature thermosetting FPC encapsulating adhesive, which is composed of the following components in parts by weight: 38 parts of acrylate oligomer, 54 parts of reactive diluent, 3 parts of thermal initiator and 5 parts of rheology modifier; wherein, the acrylate oligomer is composed of difunctional polyurethane acrylate and fatty acid modified epoxy acrylate resin in a weight ratio of 1:1, the reactive diluent is composed of IBOA, CTFA and ACMO in a weight ratio of 1:1:1, the thermal initiator is composed of azobisisobutyronitrile and dilauryl peroxide in a weight ratio of 2:1, and the rheology modifier is composed of organobentonite and polyamide wax in a weight ratio of 5:1; the specific preparation steps of the single-component, low-temperature thermosetting FPC encapsulating adhesive are as follows: (1) Add the difunctional polyurethane acrylate, fatty acid modified epoxy acrylate resin, IBOA, CTFA and ACMO to the mixing tank, stir evenly to obtain the first mixture, wherein the stirring speed is 500 r / min and the stirring time is 10 (2) Add organic bentonite and polyamide wax to the first mixture, stir evenly to obtain the second mixture, wherein the stirring speed is 2000 r / min and the stirring time is 30 min; (3) Add azobisisobutyronitrile and dilauryl peroxide to the second mixture, stir evenly, filter with a 150 mesh filter bag to obtain a single-component medium-low temperature thermosetting FPC encapsulating adhesive; wherein the stirring speed is 1200 r / min, the temperature inside the reactor is controlled at 10 ℃ during stirring, and the stirring time is 10 min.

[0023] The prepared encapsulating adhesive is applied on a dispensing machine, with the application temperature controlled at 25~35 ℃. It can be fully cured in 20 minutes at 90 ℃.

[0024] Example 4 This example provides a single-component, low-temperature thermosetting FPC encapsulating adhesive, which consists of the following components in parts by weight: 40 parts of acrylate oligomer, 51 parts of reactive diluent, 3 parts of thermal initiator, and 6 parts of rheology modifier; wherein, the acrylate oligomer is a fatty acid modified epoxy acrylate resin, the reactive diluent is composed of CTFA and ACMO in a weight ratio of 2:1, the thermal initiator is composed of benzoyl peroxide and dilauryl peroxide in a weight ratio of 4:1, and the rheology modifier is composed of fumed silica and polyamide wax in a weight ratio of 10:1; the specific preparation steps of the single-component, low-temperature thermosetting FPC encapsulating adhesive are as follows: (1) Add fatty acid modified epoxy acrylate resin, CTFA and ACMO to a mixing tank and stir evenly to obtain a first mixture, wherein the stirring speed is 500 r / min and the stirring time is 10 min; (2) Add fumed silica and polyamide wax to the first mixture and stir evenly to obtain a second mixture, wherein the stirring speed is 2000 r / min. (3) Add benzoyl peroxide and dilauryl peroxide to the second mixture, stir evenly, filter with a 150-mesh filter bag to obtain a single-component medium-low temperature thermosetting FPC encapsulating adhesive, wherein the stirring speed is 1000 r / min, the temperature inside the reactor is controlled at 10 ℃ during stirring, and the stirring time is 10 min.

[0025] The prepared encapsulating adhesive is applied on a dispensing machine, with the application temperature controlled at 25~35 ℃. It can be fully cured in 20 minutes at 90 ℃.

[0026] Comparative Example 1 This comparative example provides a single-component, low-temperature thermosetting FPC encapsulating adhesive, whose composition and preparation method are basically the same as those in Example 1, except that the reactive diluent is IBOA.

[0027] The prepared encapsulating adhesive is applied on a dispensing machine, with the application temperature controlled at 25~35 ℃. It can be fully cured in 40 minutes at 100 ℃.

[0028] Comparative Example 2 provides a single-component, low-temperature thermosetting FPC encapsulating adhesive, whose composition and preparation method are basically the same as those in Example 1, except that the reactive diluent is CTFA.

[0029] The prepared encapsulating adhesive is applied on a dispensing machine, with the application temperature controlled at 25~35 ℃. It can be fully cured in 35 minutes at 100 ℃.

[0030] Comparative Example 3 provides a single-component, low-temperature thermosetting FPC encapsulating adhesive, whose composition and preparation method are basically the same as those in Example 1, except that the reactive diluent is ACMO.

[0031] The prepared encapsulating adhesive is applied on a dispensing machine, with the application temperature controlled at 25~35 ℃. It can be fully cured in 20 minutes at 90 ℃.

[0032] Comparative Example 4 provides a single-component, low-temperature thermosetting FPC encapsulating adhesive. Its composition and preparation method are basically the same as those in Example 1, except that the thermal initiator is DCP (diisopropylbenzene peroxide).

[0033] The prepared encapsulating adhesive is applied on a dispensing machine, with the application temperature controlled at 25~35 ℃. It takes 30 minutes at 120 ℃ to fully cure.

[0034] Comparative Example 5: A commercially available FPC encapsulating adhesive, CT6010, is provided as a comparative example.

[0035] Apply the encapsulating adhesive using a dispensing machine, keeping the application temperature between 25 and 35°C. It will fully cure at 160°C for 30 minutes.

[0036] Performance tests and results: The performance of the single-component low-temperature thermosetting FPC encapsulants of Examples 1-4 and Comparative Examples 1-5 were tested respectively. The performance test results of each encapsulant are shown in Table 1.

[0037] Table 1 Performance test results of each encapsulant

[0038] As shown in Table 1, compared to Comparative Examples 1-3, the encapsulating adhesives of Examples 1-4 can achieve an elongation at break of ≥80% while shortening the curing time; compared to Comparative Example 4, the encapsulating adhesives of Examples 1-4 can reduce the curing temperature and shorten the curing time; compared to Comparative Example 5 (commercially available CT6010), the encapsulating adhesives of Examples 1-4 can reduce the curing temperature and shorten the curing time while ensuring hardness and elongation at break. This indicates that the single-component low-temperature thermosetting FPC encapsulating adhesive provided in this application can reduce the curing temperature and shorten the curing time while ensuring the mechanical properties after curing, thereby improving curing efficiency and reducing energy consumption. In addition, the single-component low-temperature thermosetting FPC encapsulating adhesive provided in this application can be applied using a dispensing machine with automated mechanical application, which is convenient and efficient, and can also meet the requirements of the encapsulating adhesive field for product mechanical properties.

[0039] Unless otherwise specified, all raw materials used in this invention are existing substances that can be purchased directly from the market.

[0040] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A single-component, low-temperature thermosetting FPC encapsulating adhesive, characterized in that, The product comprises, by weight, the following components: 20-50 parts of acrylate oligomer, 20-60 parts of reactive diluent, 0.5-5 parts of thermal initiator, and 1-10 parts of rheology modifier; wherein the reactive diluent is composed of a first reactive diluent and a second reactive diluent, the first reactive diluent comprising ACMO, and the second reactive diluent comprising at least one of IBOA and CTFA; the thermal initiator comprising at least one of azobisisobutyronitrile, azobisisobutyronitrile, benzoyl peroxide, and dilauryl peroxide.

2. The single-component, low-temperature thermosetting FPC encapsulating adhesive according to claim 1, characterized in that, The acrylate oligomers include at least one of difunctional polyurethane acrylate resins and fatty acid-modified epoxy acrylate resins.

3. The single-component, low-temperature thermosetting FPC encapsulating adhesive according to claim 1, characterized in that, The rheology modifier includes at least one of fumed silica, organobentonite, and polyamide wax.

4. The preparation method of the single-component low-temperature thermosetting FPC encapsulating adhesive according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Add the acrylate oligomer and reactive diluent to the reaction vessel and stir to obtain the first mixture; S2. Add a rheology modifier to the first mixture and stir to obtain a second mixture; S3. Add a thermal initiator to the second mixture and stir to obtain a single-component medium-low temperature thermosetting FPC encapsulating adhesive.

5. The preparation method of the single-component low-temperature thermosetting FPC encapsulating adhesive according to claim 4, characterized in that, In step S1, the stirring speed is 300~600 r / min and the stirring time is 10~30 min.

6. The preparation method of the single-component low-temperature thermosetting FPC encapsulating adhesive according to claim 4, characterized in that, In step S2, the stirring speed is 1500~2500 r / min and the stirring time is 20~30 min.

7. The preparation method of the single-component low-temperature thermosetting FPC encapsulating adhesive according to claim 4, characterized in that, In step S3, the stirring speed is 800~1200 r / min and the stirring time is 10~20 min.

8. The preparation method of the single-component low-temperature thermosetting FPC encapsulating adhesive according to claim 4, characterized in that, In step S3, the stirring temperature is 10~20 ℃.

9. The preparation method of the single-component low-temperature thermosetting FPC encapsulating adhesive according to claim 4, characterized in that, In step S3, a thermal initiator is added to the second mixture, and after stirring, the mixture is filtered to obtain a single-component medium-low temperature thermosetting FPC encapsulating adhesive.

10. The preparation method of the single-component low-temperature thermosetting FPC encapsulating adhesive according to claim 9, characterized in that, In step S3, the filtration is performed using a filter bag, wherein the filter bag has a mesh size of 500 mesh.

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