Waterproof breathable glue for sealing mobile phone module and preparation method thereof

Abstract

The invention relates to a waterproof breathable adhesive for sealing a mobile phone module. The waterproof breathable adhesive comprises the following components in parts by weight: 70-90 parts of alkoxy-terminated polydimethylsiloxane, 0-20 parts of dimethyl silicone oil, 75-100 parts of diatomite, 0-25 parts of ground calcium carbonate, 1-2 parts of color paste, 0.5-3 parts of an alkylsilane coupling agent, 1-4 parts of fumed silica and 0.2-0.5 part of a catalyst. According to the invention, alkoxy-terminated polydimethylsiloxane is taken as a base material, a continuous waterproof layer can be formed after colloid curing, invasion of liquid water is effectively prevented, diatomite with a porous structure is introduced as a filler, and gas diffusion and transmission channels are formed by using micropores and mesopores which are communicated with each other, so that the gas diffusion and transmission efficiency is improved. The diatomite can balance the air pressure inside and outside the colloid to prevent the sealing failure and realize the ventilation effect, micron-sized air holes are formed by the diatomite after the colloid is cured, the air permeability is realized, the permeation of liquid water can be avoided, the waterproofness is ensured, and the surface modification effect of the alkyl silane coupling agent is combined to achieve the waterproof effect. Therefore, the waterproofness and air permeability of the cured colloid are further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of colloid preparation, and particularly relates to a waterproof and breathable adhesive for sealing mobile phone modules and a preparation method thereof. Background Art

[0002] With the development trend of mobile phones towards being thinner and lighter, its components are moving towards miniaturization and integration, forming various modules to assist in the thinner and lighter design, which poses higher requirements for the waterproof and breathable sealing of mobile phones. The waterproof and breathability of electronic device sealing, on the one hand, can protect internal components, avoid moisture infiltration that causes short circuits, corrosion, and damage to precision electronic components such as circuit boards, chips, and batteries, and at the same time block the entry of dust and impurities to prevent affecting heat dissipation and contact with components, thereby ensuring the normal functions and stability of mobile phones; on the other hand, by maintaining air pressure balance, it can avoid deformation of the mobile phone shell, warping of the screen, and damage to components, and can also ensure the normal operation of acoustic components to ensure sound transmission and reception.

[0003] Currently, there are two solutions for electronic device sealing, namely composite films and sealants. Among them, the waterproof and breathable solution of composite films requires multiple films to be laminated in advance, and at the same time, cutting and positioning are required during assembly, resulting in relatively large losses. Therefore, the use of sealants in combination with dispensing machines is more adaptable to the fast pace and high efficiency of electronic production. However, currently, conventional sealants often have poor breathability in order to achieve better waterproof effects, and are prone to cause deformation and damage to electronic devices during thermal expansion and contraction. Therefore, there is an urgent need to develop a sealant that takes into account both waterproof and breathable properties. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a waterproof and breathable adhesive for sealing mobile phone modules and a preparation method thereof.

[0005] The technical solution adopted by the present invention is as follows:

[0006] On the one hand, the present invention provides a waterproof and breathable adhesive for sealing mobile phone modules, including the following components in parts by weight:

[0007] 70 - 90 parts of alkoxy-terminated polydimethylsiloxane, 0 - 20 parts of dimethyl silicone oil, 75 - 100 parts of diatomaceous earth, 0 - 25 parts of heavy calcium carbonate, 1 - 2 parts of color paste, 0.5 - 3 parts of alkyl silane coupling agent, 1 - 4 parts of fumed silica, and 0.2 - 0.5 parts of catalyst.

[0008] A waterproof and breathable adhesive for mobile phone module sealing proposed by the present invention uses alkoxy-terminated polydimethylsiloxane as the base material, which can form a continuous waterproof layer after the colloid is cured, effectively preventing the intrusion of liquid water. At the same time, diatomaceous earth with a porous structure is introduced as a filler, and its interconnected micropores and mesopores form channels for gas diffusion and transmission, which can balance the air pressure inside and outside the colloid to prevent sealing failure and achieve the effect of breathability. Moreover, the diatomaceous earth forms micron-sized pores after the colloid is cured, which can achieve breathability while avoiding the penetration of liquid water and ensure waterproofness. Combining with the surface modification effect of alkylsilane coupling agent, it can increase the oil absorption value of diatomaceous earth, improve the compatibility and dispersibility of diatomaceous earth in the system, form a more abundant and evenly distributed porous structure, and the alkylsilane coupling agent itself also has hydrophobicity, thereby further improving the waterproofness and breathability of the cured colloid.

[0009] Preferably, the alkoxy-terminated polydimethylsiloxane is dimethoxy-terminated polydimethylsiloxane.

[0010] Preferably, the particle size of the diatomaceous earth is 200 - 700 mesh.

[0011] Preferably, the alkylsilane coupling agent is at least one of n-propyltriethoxysilane, n-hexyltriethoxysilane, n-octyltriethoxysilane, n-dodecyltrimethoxysilane, and n-hexadecyltrimethoxysilane.

[0012] Preferably, the catalyst is organotin.

[0013] On the other hand, the present invention provides a preparation method of a waterproof and breathable adhesive for mobile phone module sealing as described in any one of the above technical solutions, including the following steps:

[0014] S1. Stir and disperse the alkoxy-terminated polydimethylsiloxane and dimethyl silicone oil for 5 - 15 min, add the pre-dried diatomaceous earth and heavy calcium carbonate, and at the same time add the alkylsilane coupling agent, evacuate to vacuum, and stir and disperse for 15 - 30 min;

[0015] S2. Continue to add the color paste and fumed silica, evacuate to vacuum, and stir and disperse for 15 - 30 min;

[0016] S3. Finally, add the catalyst, evacuate to vacuum, and stir and disperse for 5 - 10 min to obtain.

[0017] Preferably, the temperature of the drying treatment is 110 °C and the time is 24 h;

[0018] The vacuum degree of the evacuation is 0.1 MPa. Description of the Drawings

[0019] Figure 1Scanning electron microscope image of the waterproof and breathable adhesive of Embodiment 1 of the present invention. Detailed implementation manners

[0020] To better understand the above technical solutions, the exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and the scope of the present invention can be fully conveyed to those skilled in the art.

[0021] Embodiment 1

[0022] A waterproof and breathable adhesive for sealing mobile phone modules, comprising, by weight:

[0023] 90 parts of dimethoxy-terminated polydimethylsiloxane, 75 parts of 300-mesh diatomaceous earth, 0.5 part of color paste, 1 part of n-hexadecyltrimethoxysilane, 2 parts of fumed silica, and 0.2 part of organotin catalyst.

[0024] It is prepared by the following method, including the following steps:

[0025] S1. In a gravity planetary disperser, stir and disperse dimethoxy-terminated polydimethylsiloxane for 10 min, add diatomaceous earth that has been pre-dried in a vacuum oven at 110 °C for 24 h, and at the same time add n-hexadecyltrimethoxysilane, evacuate to a vacuum degree of 0.1 MPa, and stir and disperse for 20 min;

[0026] S2. Continue to add color paste and fumed silica, evacuate to a vacuum degree of 0.1 MPa, and stir and disperse for 20 min;

[0027] S3. Finally, add organotin catalyst, evacuate to a vacuum degree of 0.1 MPa, and stir and disperse for 10 min to obtain.

[0028] The waterproof and breathable adhesive prepared in this embodiment was tested by SEM (magnification 2000 times). From Figure 1 It can be seen that micron-sized pores are formed by diatomaceous earth on the surface of the adhesive layer, which can ensure that liquid water cannot pass through while improving the air permeability of the adhesive layer, taking into account both the waterproofness and air permeability of the adhesive layer.

[0029] Embodiment 2

[0030] A waterproof and breathable adhesive for sealing mobile phone modules, comprising, by weight:

[0031] 80 parts of dimethoxy - terminated polydimethylsiloxane, 10 parts of dimethyl silicone oil, 90 parts of 300 - mesh diatomaceous earth, 1 part of color paste, 3 parts of n - hexadecyltrimethoxysilane, 1 part of fumed silica, 0.5 part of organotin catalyst.

[0032] It is prepared by the following method, including the following steps:

[0033] S1. In a gravity planetary disperser, stir and disperse dimethoxy - terminated polydimethylsiloxane and dimethyl silicone oil for 10 min, add diatomaceous earth that has been pre - dried in a vacuum oven at 110 °C for 24 h, and at the same time add n - hexadecyltrimethoxysilane, evacuate to a vacuum degree of 0.1 MPa, and stir and disperse for 20 min;

[0034] S2. Continue to add color paste and fumed silica, evacuate to a vacuum degree of 0.1 MPa, and stir and disperse for 20 min;

[0035] S3. Finally, add organotin catalyst, evacuate to a vacuum degree of 0.1 MPa, and stir and disperse for 10 min to obtain.

[0036] Example 3

[0037] A waterproof and breathable adhesive for mobile phone module sealing, including by weight:

[0038] 70 parts of dimethoxy - terminated polydimethylsiloxane, 20 parts of dimethyl silicone oil, 80 parts of 500 - mesh diatomaceous earth, 10 parts of heavy calcium carbonate, 2 parts of color paste, 2 parts of n - hexadecyltrimethoxysilane, 1 part of n - dodecyltrimethoxysilane, 1 part of fumed silica, 0.5 part of organotin catalyst.

[0039] It is prepared by the following method, including the following steps:

[0040] S1. In a gravity planetary disperser, stir and disperse dimethoxy - terminated polydimethylsiloxane and dimethyl silicone oil for 10 min, add diatomaceous earth and heavy calcium carbonate that have been pre - dried in a vacuum oven at 110 °C for 24 h, and at the same time add n - hexadecyltrimethoxysilane and n - dodecyltrimethoxysilane, evacuate to a vacuum degree of 0.1 MPa, and stir and disperse for 20 min;

[0041] S2. Continue to add color paste and fumed silica, evacuate to a vacuum degree of 0.1 MPa, and stir and disperse for 20 min;

[0042] S3. Finally, add organotin catalyst, evacuate to a vacuum degree of 0.1 MPa, and stir and disperse for 10 min to obtain.

[0043] Comparative Example 1

[0044] The main difference between this comparative example and Example 1 is that heavy calcium carbonate is used to replace diatomite in equal amounts.

[0045] Comparative Example 2

[0046] The main difference between this comparative example and Example 1 is that talcum powder is used to replace diatomite in equal amounts.

[0047] The colloids prepared in Examples 1 - 3 and Comparative Examples 1 - 2 were subjected to performance tests, and the results are recorded in Table 1. The test methods are as follows:

[0048] Viscosity: Tested at 23 ± 2°C and 50 ± 5% RH using a DV2T type rotational viscometer from Brookfield Engineering Laboratories, Inc. (USA), with a No. 65 rotor and a rotational speed of 5 rpm.

[0049] Thixotropy index: Tested at 23 ± 2°C and 50 ± 5% RH using a DV2T type rotational viscometer from Brookfield Engineering Laboratories, Inc. (USA), with a No. 65 rotor. The viscosities at rotational speeds of 0.5 rpm and 5 rpm were measured respectively, and the ratio is the thixotropy index.

[0050] Surface drying time: At 23 ± 2°C and 50 ± 5% RH, gently touch the surface of the colloid with your hand every minute, and the time when the surface forms a skin is the surface drying time.

[0051] Environmental friendliness: Test the contents of halogen and heavy metal elements using an X-ray fluorescence spectrometer from Thermo Fisher Scientific.

[0052] Sizing process: Use a 0.25 mm needle, and observe the glue discharge situation with a dispensing machine.

[0053] Bonding strength: Use a polyamide plastic substrate, control the adhesive layer thickness at 0.25 mm, and the bonding area at 25 mm * 12.5 mm. After curing, test the bonding strength with a universal tensile testing machine, and the tensile rate is 5 mm / min.

[0054] Air permeability: Prepare an adhesive layer with a thickness of 0.5 mm, install the prepared sample on the test fixture of the air permeability meter, apply a pressure of 0.5 MPa, continuously test for 5 min, and observe whether the adhesive layer breaks.

[0055] Water absorption rate: The cured glue is soaked in 100 ml of deionized water, placed at 25°C for 24 hours, and then taken out to test the water absorption rate of the glue.

[0056] Table 1

[0057]

[0058]

[0059] As can be seen from Table 1, in Examples 1-3 of the present invention, the combination of dimethoxy-terminated polydimethylsiloxane and diatomaceous earth can obtain a sealant that takes into account both waterproofness and breathability. By comparing Example 1 with Comparative Examples 1-2, it can be seen that in Comparative Example 1 without adding diatomaceous earth and in Comparative Example 2 using layered talc powder as a filler, the breathability of the colloid after curing is poor, and the effects of the examples of the present invention cannot be achieved.

[0060] In summary, the advantages of the waterproof and breathable adhesive for mobile phone module sealing of the present invention are as follows:

[0061] (1) Using alkoxy-terminated polydimethylsiloxane (dimethoxy-terminated polydimethylsiloxane) as the base material, its low surface tension enables it to spread rapidly on the surface of the object, evenly cover and fill the micro-pores, forming a preliminary waterproof barrier; due to its excellent chemical stability, the silicon-oxygen bond is not easily eroded by water, acids, alkalis, salts, etc. When in contact with water for a long time, the molecular structure remains intact, maintaining the waterproof performance; its good elasticity allows it to remain sealed when the electronic device is deformed by external forces, preventing water from seeping in; the three-dimensional cross-linked network structure formed after curing is dense, and the hydrophobic groups such as methyl in the molecular structure can strongly repel water molecules, making it difficult for them to adhere to and penetrate the adhesive layer. Combining with an alkyl coupling agent enhances the overall waterproofness, so in the waterproof sealing of electronic devices, it effectively blocks the intrusion of moisture and ensures the stable and reliable operation of electronic devices in different environments.

[0062] (2) Using diatomaceous earth with a porous structure as a filler, the interconnected micropores and mesopores form channels for gas diffusion and transmission, which can allow an appropriate amount of air to exchange inside and outside the module, ensuring that the air pressure inside the module always remains stable under different environmental temperatures and usage conditions, avoiding problems such as seal failure, shell deformation, or screen warping caused by excessive internal and external air pressure differences due to temperature changes; at the same time, through the surface modification of an alkylsilane coupling agent, the oil absorption value of diatomaceous earth is significantly increased, improving its compatibility and dispersibility in the system, so that the addition amount of diatomaceous earth in the colloid can be further increased, ensuring the formation of more abundant and uniform pores and improving the overall breathability. In addition, the introduction of an alkylsilane coupling agent can also improve the bonding strength between the colloid and the polyamide plastic in the mobile phone module, ensuring that there are no gaps or degumming phenomena in the colloid during long-term use.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A waterproof and breathable adhesive for sealing a mobile phone module, characterized in that: Including by weight: 70-90 parts of alkoxy-terminated polydimethylsiloxane, 0-20 parts of dimethyl silicone oil, 75-100 parts of diatomaceous earth, 0-25 parts of heavy calcium carbonate, 1-2 parts of color paste, 0.5-3 parts of alkyl silane coupling agent, 1-4 parts of fumed silica, and 0.2-0.5 parts of catalyst.

2. The waterproof and breathable adhesive for sealing a mobile phone module according to claim 1, characterized in that: The alkoxy-terminated polydimethylsiloxane is bismethoxy-terminated polydimethylsiloxane.

3. The waterproof and breathable adhesive for sealing a mobile phone module according to claim 1, characterized in that: The particle size of the diatomaceous earth is 200-700 meshes.

4. The waterproof and breathable adhesive for sealing a mobile phone module according to claim 1, characterized in that: The alkylsilane coupling agent is at least one of n-propyltriethoxysilane, n-hexyltriethoxysilane, n-octyltriethoxysilane, n-dodecyltrimethoxysilane and n-hexadecyltrimethoxysilane.

5. The waterproof and breathable adhesive for sealing a mobile phone module according to claim 1, characterized in that: The catalyst is organotin.

6. A method for preparing the waterproof and breathable adhesive for sealing a mobile phone module according to any one of claims 1 to 5, comprising the following steps: S1. Stir and disperse the alkoxy-terminated polydimethylsiloxane and dimethyl silicone oil for 5-15 minutes, add the diatomaceous earth and heavy calcium carbonate that have been dried in advance, and add the alkyl silane coupling agent at the same time, evacuate, and stir and disperse for 15-30 minutes; S2. Continue to add color paste and fumed silica, evacuate, and stir and disperse for 15-30 minutes; S3. Finally, add the catalyst, evacuate the mixture, and stir and disperse for 5-10 minutes.

7. The method for preparing the waterproof and breathable adhesive for sealing a mobile phone module according to claim 6, characterized in that: The drying temperature is 110°C and the drying time is 24 hours; The vacuum degree of the vacuum pumping is 0.1 MPa.

Images