Insulation sealing coating adhesive

Abstract

The embodiment of the invention relates to the technical field of insulating adhesives, and discloses an insulating sealing coating adhesive which comprises 60-80 parts of a modified styrene-butadiene-styrene block copolymer, 0.3-1 part of a ketimine curing agent, 2-8 parts of an aromatic amine curing agent, 3-8 parts of methyl silicone oil and 12-26 parts of petroleum ether, wherein the modified styrene-butadiene-styrene block copolymer is obtained by epoxidation of a styrene-butadiene-styrene block copolymer (SBS), the molecular weight of the styrene-butadiene-styrene block copolymer is 7000-11000, the substance amount fraction of a PB end (polybutadiene chain segment) is 70-85%, and the ratio of a branched chain structure to a straight chain structure in the PB end is 1: 2-1: 3. The insulation sealing coating adhesive has the characteristics of high reliability and uniform coating in multiple axial directions, especially in the vertical direction (namely the z-axis direction) through the structural characteristics of the insulation sealing coating adhesive and the compounding of the insulation sealing coating adhesive and a multi-element curing agent, is convenient to spray and is beneficial to application to precise components.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of insulating adhesives, and in particular, to an insulating sealing coating adhesive. Background Art

[0002] PCBA, or printed circuit board assembly, is a circuit board assembly with specific functions formed by soldering electronic components to a PCB. It achieves the preset functions of the circuit board through the coordinated work of various components, and has therefore become a core component of electronic equipment. The structural and functional integrity and durability of PCBA play a decisive role in the performance and function of electronic products. In order to avoid the negative impact of environmental factors such as moisture on the working stability and life of components, protective materials are usually applied to the pin position or the entire component after the precision components on the PCBA complete the mounting process.

[0003] As onboard components tend to be denser and the reliability requirements of electronic components are increasing, traditional protective materials are gradually exposed to new problems in practical applications. For example, due to the low viscosity and poor thixotropy of traditional three-proof paint, it is difficult to achieve uniform coating for components with larger dimensions in the Z-axis direction (or vertical direction), especially on the vertical surface of the components, resulting in a decrease in the protective effect; however, if the viscosity of the protective material is increased, the protective material cannot be adapted to the spraying method, which increases the difficulty of the coating process. In addition, the reliability of traditional protective materials is limited. Under harsh environmental conditions such as uHAST or PCT, it is usually difficult to pass the test. In the SIR test under double 85 conditions, it can only last for 200 to 300 hours.

[0004] Therefore, in order to meet the current changing trend of components, how to provide a protective material with high reliability, high adhesion and easy coating is a technical problem that needs to be solved urgently by people in this field. Summary of the invention

[0005] In order to solve the above problems, the purpose of the invention of this application is to provide an insulating sealing coating adhesive, which obtains high reliability and coating uniformity especially in the Z-axis direction through the compounding of modified styrene-butadiene-styrene block copolymer, ketimine curing agent and aromatic amine curing agent, and is also easy to spray, so as to facilitate coating on PCB and precision electronic components.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] An insulating sealing coating adhesive, characterized in that it comprises the following components in proportion by mass:

[0008]

[0009] The modified styrene-butadiene-styrene block copolymer has a structural formula as described in formula (I):

[0010]

[0011] Preferably, the molecular weight of the styrene-butadiene-styrene block copolymer is 7,000 - 11,000, the molar fraction of the PB end (polybutadiene chain segment) is 70 - 85%, and the molar ratio of the branched-chain structure to the straight-chain structure in the PB end is (1:2) - (1:3).

[0012] Preferably, it further comprises 3 - 5 parts of fumed silica.

[0013] Preferably, the modified styrene-butadiene-styrene block copolymer is obtained by heating styrene-butadiene-styrene block copolymer (SBS) with H2O2 under the action of formic acid and a catalyst, and the molar ratio of H2O2 to SBS is (300:1) - (600:1).

[0014] Preferably, the molar ratio of the formic acid to the H2O2 is (1:0.9) - (2:1).

[0015] Preferably, the heating temperature is 65°C - 85°C.

[0016] Preferably, the preparation method of the modified styrene-butadiene-styrene block copolymer comprises: dissolving SBS and formic acid in an alkane solution, adding the catalyst, heating and slowly dropping H2O2 while stirring;

[0017] Wherein, the concentration of SBS in the alkane solvent is 80 - 105 g / L. The alkane solvent can be cyclohexane or other saturated hydrocarbons with a boiling point above the reaction temperature and capable of dissolving SBS.

[0018] Preferably, in the step of dropping the H2O2, the H2O2 solution is used, and the concentration of the H2O2 solution is not less than 25%.

[0019] Preferably, the aromatic amine curing agent is one or more of diaminophenylmethane, diaminodiphenylsulfone, phthalic diamine trimer and its derivatives.

[0020] Preferably, the ketimine curing agent is prepared by condensing methyl isopropyl ketone / methyl isobutyl ketone with a tertiary amine.

[0021] Based on the above technical solutions, the present invention has the following technical effects:

[0022] 1. An insulating and sealing coating adhesive provided by the present invention. The insulating and sealing coating adhesive obtains high reliability and uniform coating in multiple axes, especially in the Z-axis, through the structural characteristics of the modified styrene-butadiene-styrene block copolymer and the compounding with ketimine curing agents and aromatic amine curing agents. At the same time, it is also convenient for spraying, so as to be coated on PCBs and precision electronic components. Due to the low viscosity characteristic, the insulating and sealing coating adhesive can be sprayed through a nozzle and adhered to the surface of the components. At this time, the insulating and sealing coating adhesive quickly achieves preliminary curing after contacting the moisture in the air, so it can adhere well to the vertical direction of the components. Subsequently, secondary curing is achieved through heating, further strengthening the properties of the formed insulating layer and making the insulating layer have high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the excellent rating in the insulating adhesive coating uniformity test of the present invention;

[0024] Figure 2 It is a schematic diagram of the good rating in the insulating adhesive coating uniformity test of the present invention;

[0025] Figure 3 It is a schematic diagram of the medium rating in the insulating adhesive coating uniformity test of the present invention;

[0026] Figure 4 It is a schematic diagram of the poor rating in the insulating adhesive coating uniformity test of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below in conjunction with specific embodiments. The present invention provides preferred embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0028] Before further describing various embodiments of the compounds / compositions and methods of the present disclosure in more detail by way of exemplary description, examples, and results, it should be understood that the embodiments of the present disclosure are not limited in their application to the details of the methods and compositions described in the following description. The description provided herein is for illustrative purposes only and is not to be construed in a limiting sense. The inventive concept of the present disclosure can have other embodiments or can be practiced or implemented in various ways. Thus, the language used herein is intended to give the broadest scope and meaning; and the embodiments are intended to be exemplary and not exhaustive and are not intended to limit the present disclosure to these specific embodiments. Moreover, it should be understood that the language and terminology employed herein are for the purpose of description and should not be considered limiting unless otherwise specified. Additionally, in the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the present disclosure.

[0029] However, it will be apparent to those of ordinary skill in the art that the embodiments of the present disclosure can be practiced without these specific details. In other instances, features known to those of ordinary skill in the art have not been described in detail to avoid unnecessary complication of the description. It is intended that all alternatives, substitutions, modifications, and equivalents that are apparent to those of ordinary skill in the art are included within the scope of the present disclosure. According to the present disclosure, all of the compounds / compositions disclosed herein and their preparation methods, applications, and uses can be prepared and implemented without undue experimentation.

[0030] Thus, although the compounds / compositions and methods of the present disclosure have been described in terms of specific embodiments, it will be apparent to those skilled in the art that changes can be made to the formulations, compounds or compositions, and / or methods and to the steps or the order of steps in the methods described herein without departing from the spirit and scope of the inventive concept of the present disclosure.

[0031] As used herein, any reference to "an embodiment" or "embodiments" means that the particular element, feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. The phrase "in an embodiment" that appears multiple times in the specification is not necessarily all referring to the same embodiment.

[0032] Unless otherwise defined herein, scientific and technical terms used in connection with the present disclosure shall have the meanings commonly understood by those of ordinary skill in the art. Additionally, unless the context otherwise requires, singular terms shall include the plural and plural terms shall include the singular.

[0033] Example 1

[0034] Preparation of Modified Styrene-Butadiene-Styrene Block Copolymer

[0035] 1 mol of styrene-butadiene-styrene (SBS) and 315 mol of formic acid were added to cyclohexane, and about 0.02 mol of cyclodextrin was added as a phase transfer catalyst. The mixture was heated to a certain temperature, and 30% hydrogen peroxide containing 450 mol of H2O2 was added evenly over 210 min with vigorous stirring. After the addition was complete, stirring was continued for more than 3 hours, and then phase separation occurred. The organic phase was washed with weakly alkaline water until neutral, and then the solvent was removed by distillation under reduced pressure to obtain the modified styrene-butadiene-styrene block copolymer.

[0036] Among them, the modified styrene-butadiene-styrene block copolymer has the structural formula shown in formula (Ⅰ):

[0037]

[0038] In this process, the SBS material was epoxidized through the process shown in formula (Ⅱ).

[0039]

[0040] In this example, the raw material SBS had a molecular weight of 9000, the molar fraction of the polybutadiene chain segment (PB end) was 80%, the molar ratio of the branched-chain structure to the straight-chain structure in the PB end was 1:2.5, the molar ratio of H2O2 to SBS was 450:1, the molar ratio of formic acid to H2O2 was 1:0.7, the stirring time was 180 minutes, the concentration of SBS in cyclohexane was 95 g / L, and the obtained modified styrene-butadiene-styrene block copolymer had a H2O2 concentration of 25%.

[0041] Preparation of insulating and sealing coating glue

[0042] 70 parts of the modified styrene-butadiene-styrene block copolymer prepared above, 0.6 part of a ketimine curing agent, 5 parts of an aromatic amine curing agent, 5.4 parts of methyl silicone oil, and 19 parts of petroleum ether were weighed and dispersed evenly in a homogenizer to obtain the insulating and sealing coating glue. Preferably, in order to maintain the properties of the insulating and sealing coating glue, it can be packaged in a sealed nitrogen-filled manner.

[0043] During application, under the conditions of an environmental humidity of 75% and a temperature of 25 °C, the example was evenly sprayed on the circuit board with a spray glue machine. After standing for at least 15 minutes, it was heated to 120 °C in an oven and cured for 15 minutes.

[0044] Example 2

[0045] Different from Example 1, the raw material SBS has a molecular weight of 11,000, where the molar fraction of the PB end is 70%, the molar ratio of the branched-chain structure to the straight-chain structure in the PB end is 1:2, the molar ratio of H2O2 to SBS is 600:1, the molar ratio of formic acid to H2O2 is 2:1, the stirring time is 180 minutes, and the concentration of SBS in cyclohexane is 105 g / L.

[0046] Example 3

[0047] Different from Example 1, the raw material SBS has a molecular weight of 7,000, where the molar fraction of the PB end is 85%, the molar ratio of the branched-chain structure to the straight-chain structure in the PB end is 1:3, the molar ratio of H2O2 to SBS is 300:1, the molar ratio of formic acid to H2O2 is 1:0.9, the stirring time is 240 minutes, and the concentration of SBS in cyclohexane is 105 g / L.

[0048] Example 4

[0049] Different from Example 1, 80 parts of the prepared modified styrene-butadiene-styrene block copolymer, 0.3 part of a ketimine curing agent, 2 parts of an aromatic amine curing agent, 5.7 parts of methyl silicone oil, and 12 parts of petroleum ether are weighed and dispersed evenly in a homogenizer to obtain an insulating and sealing coating adhesive.

[0050] Example 5

[0051] Different from Example 1, during the preparation of the modified styrene-butadiene-styrene block copolymer, the concentration of SBS in cyclohexane is 80 g / L. 60 parts of the prepared modified styrene-butadiene-styrene block copolymer, 1 part of a ketimine curing agent, 8 parts of an aromatic amine curing agent, 5 parts of methyl silicone oil, and 26 parts of petroleum ether are weighed and dispersed evenly in a homogenizer to obtain an insulating and sealing coating adhesive.

[0052] Example 6

[0053] Different from Example 1, 66 parts of the prepared modified styrene-butadiene-styrene block copolymer, 0.6 part of a ketimine curing agent, 5 parts of an aromatic amine curing agent, 8 parts of methyl silicone oil, 20.4 parts of petroleum ether, and 4 parts of fumed silica are weighed and dispersed evenly in a homogenizer to obtain an insulating and sealing coating adhesive.

[0054] Comparative Example 1

[0055] Different from Example 1, the raw material SBS has a molecular weight of 13,000.

[0056] Comparative Example 2

[0057] Different from Example 1, the raw material SBS has a molecular weight of 5000.

[0058] Comparative Example 3

[0059] Different from Example 1, the molar fraction of the PB end in the raw material SBS is 60%.

[0060] Comparative Example 4

[0061] Different from Example 1, the molar fraction of the PB end in the raw material SBS is 95%.

[0062] Comparative Example 5

[0063] Different from Example 1, in the PB end of the raw material SBS, the molar ratio of the branched-chain structure to the straight-chain structure is 1:4.

[0064] Comparative Example 6

[0065] Different from Example 1, in the PB end of the raw material SBS, the molar ratio of the branched-chain structure to the straight-chain structure is 1:1.

[0066] Comparative Example 7

[0067] Different from Example 1, during the preparation process, the molar ratio of H2O2 to SBS is 200:1.

[0068] Comparative Example 8

[0069] Different from Example 1, during the preparation process, the molar ratio of H2O2 to SBS is 800:1.

[0070] Comparative Example 9

[0071] Different from Example 1, weigh 74 parts of the above-prepared modified styrene-butadiene-styrene block copolymer, 0.6 part of a ketimine curing agent, 1 part of an aromatic amine curing agent, 5.4 parts of methyl silicone oil, and 19 parts of petroleum ether, and disperse them evenly in a homogenizer to obtain the coating adhesive of the comparative example.

[0072] Comparative Example 10

[0073] Different from Example 1, weigh 63 parts of the above-prepared modified styrene-butadiene-styrene block copolymer, 0.6 part of a ketimine curing agent, 12 parts of an aromatic amine curing agent, 5.4 parts of methyl silicone oil, and 19 parts of petroleum ether, and disperse them evenly in a homogenizer to obtain the coating adhesive of this example.

[0074] Comparative Example 11

[0075] Different from Example 1, 70.5 parts of the modified styrene-butadiene-styrene block copolymer prepared above, 0.1 part of ketimine curing agent, 5 parts of aromatic amine curing agent, 5.4 parts of methyl silicone oil and 19 parts of petroleum ether were weighed and dispersed evenly in a homogenizer to obtain the coating adhesive of this example.

[0076] Comparative Example 12

[0077] Different from Example 1, 68.6 parts of the modified styrene-butadiene-styrene block copolymer prepared above, 2 parts of ketimine curing agent, 5 parts of aromatic amine curing agent, 5.4 parts of methyl silicone oil and 19 parts of petroleum ether were weighed and dispersed evenly in a homogenizer to obtain the coating adhesive of this example.

[0078] The insulating adhesives prepared in Examples 1-6 and Comparative Examples 1-12 above were measured for viscosity by a cone-plate viscometer CP52 at 25 °C at a rotational speed of 2 revolutions per minute (rpm); a weather resistance experiment was carried out under the test conditions of a temperature of 85 °C and a relative humidity of 85%. The specific method of the weather resistance experiment was to place the sample in a double 85 test chamber and start timing. After a certain period of time, it was taken out and the resistivity was measured with a high resistance meter under the condition of 250 V. When the resistivity was higher than 10 8 Ω / cm, it was returned to the test chamber to continue timing; the above operation was repeated until the resistivity was lower than 10 8 Ω / cm, which was regarded as the failure of the insulating adhesive, and the total time in the test chamber was recorded as the weather resistance performance; and the insulating adhesive was coated on the PCBA sample by spraying, and its coating uniformity was judged by its wrapping degree in the Z-axis direction (i.e., the vertical direction). The specific evaluation criteria refer to Figures 1 to 4 ; the data results shown in Table 1 were obtained through the above test experiments.

[0079] Table 1 Test results of the insulating adhesive performance of each experimental group

[0080]

[0081]

[0082] From the test data in Table 1, it can be seen that the viscosities of the insulating sealant coatings prepared in Examples 1 to 6 of this example are between 9000 and 19000, and the uniformity of the Z-axis coating is excellent or above. While adapting to the spraying process, it also has excellent wrapping performance, can evenly coat the glue, and is beneficial to the application on precision components. In addition, the initial insulation degree of the insulating sealant coatings in Examples 1 to 6 can reach 10 10 Ω / cm or more, and it can reach more than 500 hours under the double 85 test without being lower than 10 8Ω / cm, taking into account insulation and reliability. Thus, it can be seen that the comprehensive performance of the insulating and sealing coating glue provided by the present invention is excellent, and it is a protective material with high reliability, high adhesion and easy coating.

[0083] The above content is only an example and description of the structure of the present invention. Its description is relatively specific and detailed, but it cannot be understood as a limitation of the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can be made, and these obvious replacement forms all belong to the protection scope of the present invention.

Claims

1. An insulating and sealing coating adhesive, characterized in that, Comprising components in the following mass parts ratio: The modified styrene-butadiene-styrene block copolymer has the structural formula as described in formula (I):

2. The insulating and sealing coating adhesive according to claim 1, wherein, The molecular weight of the styrene-butadiene-styrene block copolymer is 7000 - 11000, wherein the molar fraction of the PB end (polybutadiene chain segment) is 70 - 85%, and the molar ratio of the branched chain structure to the straight chain structure in the PB end is (1:2) - (1:3).

3. The insulating and sealing coating adhesive according to claim 1, characterized in that It also includes 3 - 5 parts of fumed silica.

4. The insulating and sealing coating adhesive according to any one of claims 2-3, characterized in that The modified styrene-butadiene-styrene block copolymer is obtained by heating styrene-butadiene-styrene block copolymer (SBS) with H2O2 under the action of formic acid and a catalyst, and the molar ratio of H2O2 to SBS is (300:1) - (600:1).

5. The insulating and sealing coating adhesive according to claim 4, wherein The molar ratio of the formic acid to the H2O2 is (1:0.9) - (2:1).

6. The insulating and sealing coating adhesive according to claim 5, characterized in that, The heating temperature is 65°C - 85°C.

7. The insulating and sealing coating adhesive according to claim 4, wherein, The preparation method of the modified styrene-butadiene-styrene block copolymer includes: dissolving SBS and formic acid in an alkane solution, adding the catalyst, heating and slowly dropping H2O2 while stirring; Among them, the concentration of SBS in the alkane solvent is 80 - 105 g / L.

8. The insulating and sealing coating adhesive according to claim 7, characterized in that, In the step of dropping the H2O2, the H2O2 solution is used, and the concentration of the H2O2 solution is not less than 25% 。 9. The insulating and sealing coating adhesive according to claim 1, characterized in that, The aromatic amine curing agent is one or more of diaminophenylmethane, diaminodiphenylsulfone, phthalic diamine trimer and its derivatives.

10. The insulating and sealing coating adhesive according to claim 1, characterized in that, The ketimine curing agent is prepared by condensing methyl isopropyl ketone / methyl isobutyl ketone with a tertiary amine.

Images