Dam glue as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of box dam adhesives, and provides a box dam adhesive and a preparation method and application thereof.The box dam adhesive comprises a component A and a component B. The component A comprises vinyl silicone oil A, cross-linked hydrogen silicone oil, white carbon black A, a tackifier A and an inhibitor; the component B comprises vinyl silicone oil B, white carbon black B, a tackifier B, a catalyst and color paste; the tackifier A and the tackifier B respectively and independently comprise an acryloyloxy-containing organic silicon tackifier; the content of silicon hydrogen groups in the cross-linked hydrogen silicone oil is 1-2 mmol / g; the white carbon black A and the white carbon black B respectively and independently comprise first white carbon black and second white carbon black, the specific surface area of the first white carbon black is 90-190 m / g, and the specific surface area of the second white carbon black is 195-300 m / g. The box dam glue provided by the invention has good thixotropy, relatively low density, small reworking residual glue rate after curing, and good construction performance and reworkability.

Description

Technical Field

[0001] This invention belongs to the field of damming adhesive technology, and particularly relates to a damming adhesive, its preparation method and application. Background Technology

[0002] In modern electronic device manufacturing, screen bonding processes are crucial to the performance and appearance of display components. Especially in applications requiring high reliability (such as resistance to high and low temperatures and high light transmittance), silicone gel (also known as filler) is often used as a filler material to achieve good optical performance and environmental adaptability. However, silicone gel presents significant problems during application: due to its inherent fluidity, it easily overflows from the screen edges during bonding, affecting not only aesthetics but also potentially contaminating other components. Furthermore, the high light transmittance of silicone gel can cause light leakage from screen gaps, resulting in light leakage that further impacts visual effects and product quality.

[0003] To overcome the aforementioned problems, screen bonding processes typically require the use of damming adhesive (DAM adhesive). DAM adhesive is generally black and effectively absorbs light, eliminating light leakage between the inner and outer screens. Simultaneously, DAM adhesive has a high thixotropic index, making it less prone to flow during application and facilitating precise coating; its low viscosity also benefits processing. Therefore, DAM adhesive plays a crucial role in screen encapsulation.

[0004] Currently, some companies use room temperature vulcanizing (RTV) silicone rubber as an alternative to DAM adhesive. However, RTV adhesive has significant drawbacks: its components can cause silicone gel "poisoning," inhibiting the curing reaction and resulting in incomplete curing or a significantly reduced reaction rate in the contact area, affecting overall encapsulation reliability. Furthermore, RTV adhesive typically has a high density (generally greater than 1.5 g / cm³), increasing overall weight and hindering device lightweighting. Another alternative is the use of single-component non-reactive adhesives. While these materials avoid gel poisoning, they often lack sufficient environmental resistance, making rework and repair extremely difficult. Regardless of whether it's RTV or non-reactive adhesive, removal is difficult when screen replacement or repair is needed, often causing substrate damage or increasing repair costs.

[0005] For example, CN108102602A discloses a damming adhesive, which, by weight percentage, comprises the following components: 20-50% high-viscosity vinyl silicone oil, 15-50% low-viscosity vinyl silicone oil, 10-30% silica, 0.1-5% hydrogen-containing silicone oil, 1-500 ppm platinum photocatalyst, 0.1-5% thixotropic agent, and 0.1-5% tackifier. This damming adhesive can be stored at room temperature and has good storage stability. It also has a low curing temperature, making it suitable for temperature-sensitive substrates and components. Furthermore, its fast curing speed can effectively improve industrial production efficiency. However, its high residual rate makes rework difficult.

[0006] Therefore, it is necessary to develop a DAM adhesive that can avoid the problem of silicone gel poisoning, while also possessing good construction performance and reworkability, in order to meet the comprehensive requirements of high-end display devices for reliability, aesthetics, and ease of maintenance. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a damming adhesive, its preparation method, and its application. The damming adhesive exhibits good thixotropy, low density, low rework residue rate after curing, and does not break when peeled, does not cause silicone gel poisoning, and has good workability and reworkability.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a damming adhesive, the damming adhesive comprising component A and component B.

[0010] Component A comprises the following components by weight:

[0011] Vinyl silicone oil A 75-85 parts

[0012] Crosslinked hydrosilicone oil 0.2-8 parts

[0013] Silica A5-15 parts

[0014] Tackifier A1 - 3 parts

[0015] Inhibitor 0.01-1 part;

[0016] Component B comprises the following components by weight:

[0017] Vinyl silicone oil B50-60 parts

[0018] 0.1-0.5 parts of silica B

[0019] Tackifier B1 - 3 parts

[0020] Catalyst 0.1-0.5 parts

[0021] 0.1-0.5 parts color paste

[0022] Tackifier A and tackifier B each independently comprise an organosilicon tackifier containing an acryloxy group.

[0023] The cross-linked hydrosilicone oil contains 1-2 mmol / g of silane groups.

[0024] The molar ratio of the hydroxyl groups in the crosslinked hydrosilicone oil to the vinyl groups in the damming adhesive is (0.25-0.50): 1.

[0025] The silica A and silica B each independently comprise a first silica and a second silica.

[0026] The specific surface area of ​​the first silica is 90-190 m² / g.

[0027] The specific surface area of ​​the second silica is 195-300 m² / g.

[0028] In this invention, the first silica has a smaller specific surface area, which adsorbs onto the surface of larger particles of the damming adhesive, blocking contact between the particles, reducing friction, and playing a role in making the system flow; the second silica has a larger specific surface area and more silanol groups on its surface, which can form a network with the damming adhesive particles, fixing the particles and playing a role in preventing sedimentation, increasing viscosity, and improving the thixotropic properties of the system.

[0029] In this invention, if the silane content in the crosslinked hydrosilicone oil is too high, some silane groups will be unable to contact and react with the vinyl group during the hydrosilylation reaction due to steric hindrance, ultimately becoming "unreacted residual hydrogen" that remains. These unreacted silane groups fail to integrate into the three-dimensional crosslinked network, resulting in incomplete curing and residue at the bottom, thus increasing the residual adhesive rate.

[0030] In this invention, if the molar ratio of the silanol group in the crosslinked hydrosilicone oil to the vinyl group in the system is too high, although the full reaction of the vinyl group is ensured, the crosslinking network density is too high. The excessive crosslinking density increases the rigidity and brittleness of the dammed adhesive, making it easy to break when the adhesive is torn, thus affecting its reworkability.

[0031] The amount of vinyl silicone oil A used in component A, by weight, can be 75 parts, 76 parts, 77 parts, 78 parts, 79 parts, or 80 parts, etc.

[0032] The amount of cross-linked silicone oil used in component A, by weight, can be 0.2 parts, 0.5 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, or 8 parts, etc.

[0033] The amount of silica A in component A, by weight, can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 parts, etc.

[0034] The amount of tackifier A, by weight, can be 1 part, 1.5 parts, 2 parts, 2.5 parts, or 3 parts, etc.

[0035] The amount of inhibitor in component A, by weight, can be 0.01 parts, 0.03 parts, 0.05 parts, 0.07 parts, 0.09 parts, or 1 part, etc.

[0036] The amount of vinyl silicone oil B, by weight, can be 50 parts, 51 parts, 52 parts, 53 parts, 54 parts, 55 parts, 56 parts, 57 parts, 58 parts, 59 parts, or 60 parts, etc.

[0037] The amount of silica B in component B, by weight, can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, or 0.5 parts, etc.

[0038] The amount of tackifier B, by weight, can be 1 part, 1.5 parts, 2 parts, 2.5 parts, or 3 parts, etc.

[0039] The amount of catalyst used in component B, by weight, can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, or 0.5 parts, etc.

[0040] The amount of color paste used in component B, by weight, can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, or 0.5 parts, etc.

[0041] The silane content in the crosslinked hydrosilicone oil can be 1 mmol / g, 1.2 mmol / g, 1.4 mmol / g, 1.6 mmol / g, 1.8 mmol / g, or 2 mmol / g, etc.

[0042] The specific surface area of ​​the first silica is 90-190 m² / g, for example, 90 m² / g, 100 m² / g, 110 m² / g, 120 m² / g, 130 m² / g, 140 m² / g, 150 m² / g, 160 m² / g, 170 m² / g, 180 m² / g, or 190 m² / g, etc.

[0043] The specific surface area of ​​the second silica is 195-300 m² / g, for example, 195 m² / g, 200 m² / g, 210 m² / g, 220 m² / g, 230 m² / g, 240 m² / g, 250 m² / g, 260 m² / g, 270 m² / g, 280 m² / g, 290 m² / g, or 300 m² / g, etc.

[0044] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0045] Preferably, the molar ratio of the silanol group in the crosslinked hydrosilicone oil to the vinyl group in the system is (0.25-0.50):1, for example, 0.25:1, 0.26:1, 0.28:1, 0.3:1, 0.32:1, 0.34:1, 0.36:1, 0.38:1, 0.4:1, 0.42:1, 0.44:1, 0.46:1, 0.48:1, or 0.5:1, etc.

[0046] Preferably, the first silica includes any one or a combination of at least two of Evonik R711, Evonik R805, Evonik R972 or Evonik R974.

[0047] Preferably, the second silica includes any one or a combination of at least two of Evonik R812, Evonik R812S, or Evonik R816.

[0048] Preferably, based on the mass of silica A or silica B as 100%, the proportion of the first silica is 6-34%, such as 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, or 34%.

[0049] Preferably, the viscosities of the vinyl silicone oil A and vinyl silicone oil B at 25 °C are each independently 500-10000 cs, for example 500 cs, 1000 cs, 2000 cs, 3000 cs, 4000 cs, 5000 cs, 6000 cs, 7000 cs, 8000 cs, 9000 cs or 10000 cs, etc.

[0050] Preferably, the vinyl content in vinyl silicone oil A and vinyl silicone oil B is independently 0.05-0.15 mmol / g, for example 0.05 mmol / g, 0.06 mmol / g, 0.07 mmol / g, 0.08 mmol / g, 0.09 mmol / g, 0.1 mmol / g, 0.11 mmol / g, 0.12 mmol / g, 0.13 mmol / g, 0.14 mmol / g or 0.15 mmol / g, etc.

[0051] Preferably, the viscosity of the crosslinked hydrosilicone oil at 25°C is 5-500 cs, such as 5 cs, 10 cs, 50 cs, 100 cs, 200 cs, 300 cs, 400 cs or 500 cs.

[0052] Preferably, the inhibitor comprises 2, 4, 6, 8 Tetramethyl 2,4,6,8 Tetravinylcyclotetrasiloxane, 1,1,3,3 Tetramethyl 1,3 Divinylsiloxane, 3 methyl 1 Butyryl 3 alcohol, 1 Ethynylcyclohexanol, 3 Phenyl 1 Butyryl 3 alcohol, 3 propyl 1 Butyryl 3 alcohol, 3 Sinki 1 Butyryl 3 Any one or a combination of at least two alcohols.

[0053] Preferably, the acryloxy-containing silicone tackifier includes γ Methacryloxypropyltrimethoxysilane, 3 The combination of any one or at least two of the following: methacryloyloxypropylmethyldimethoxysilane or methacryloyloxyethyltrimethylammonium chloride copolymer.

[0054] Preferably, the catalyst comprises a platinum catalyst.

[0055] Preferably, the platinum catalyst comprises any one or a combination of at least two of the following: an alcoholic solution of chloroplatinic acid, a platinum catalyst coordinated with tetrahydrofuran, or a platinum catalyst coordinated with divinyltetramethylsiloxane.

[0056] Preferably, the platinum content in the platinum catalyst is 4000-6000 ppm, such as 4000 ppm, 4500 ppm, 5000 ppm, 5500 ppm or 6000 ppm.

[0057] Preferably, the color paste includes a black color paste.

[0058] Preferably, the mass ratio of component A to component B is 1:(0.8-1.2), for example, 1:0.8, 1:0.9, 1:1, 1:1.1 or 1:1.2, etc.

[0059] Secondly, the present invention provides a method for preparing the damming adhesive described in the first aspect, the method comprising the following steps:

[0060] (1) Mix vinyl silicone oil A, crosslinked hydrosilicone oil, silica A, tackifier A and inhibitor to obtain component A;

[0061] (2) Mix vinyl silicone oil B, silica B, tackifier B, catalyst and color paste to obtain component B;

[0062] (3) Mix component A and component B to obtain the dam sealant.

[0063] Preferably, in steps (1)-(3), the mixing time is independently 0.5-2 h, for example 0.5 h, 1 h, 1.5 h or 2 h.

[0064] Thirdly, the present invention provides an application of the damming adhesive as described in the first aspect in a screen.

[0065] Compared with the prior art, the present invention has the following beneficial effects:

[0066] The damming adhesive provided by this invention has good thixotropic properties, with a thixotropic index greater than 2.5, low density, less than 5% residual adhesive after curing, and will not break when peeled off, will not cause silicone gel poisoning, has good workability and reworkability, and the residual adhesive is easy to clean. Detailed Implementation

[0067] 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.

[0068] The raw material information involved in the specific embodiments of this invention is as follows:

[0069] Vinyl silicone oil: viscosity 500 cs, vinyl content 0.15 mmol / g, Anbia, ANDISILVS500.

[0070] Vinyl silicone oil: viscosity 1000 cs, vinyl content 0.12 mmol / g, Anbia, ANDISILVS1000.

[0071] Vinyl silicone oil: viscosity 2000 cs, vinyl content 0.1 mmol / g, Ambiar, ANDISILVS2000.

[0072] Vinyl silicone oil: viscosity 5000 cs, vinyl content 0.06 mmol / g, Ambiar, ANDISILVS5000.

[0073] Vinyl silicone oil: viscosity 10000 cs, vinyl content 0.05 mmol / g, Ambiar, ANDISILVS10000.

[0074] Crosslinked hydrosilicone oil: viscosity 90 cs, silane content 2 mmol / g, Runhe, RH-H138.

[0075] Crosslinked hydrosilicone oil: viscosity 30 cs, silane content 1.5 mmol / g, Runhe, RH-H57.

[0076] Crosslinked hydrosilicone oil: viscosity 60 cs, silane content 1.7 mmol / g, Runhe, RH-H33.

[0077] Crosslinked hydrosilicone oil: viscosity 80 cs, silane content 1 mmol / g, Runhe, RH-H86.

[0078] Crosslinked hydrosilicone oil: viscosity 20 cs, silane content 1.2 mmol / g, Runhe, RH-H35.

[0079] First-class silica: Evonik, R974, specific surface area: 150-190 m² / g; Evonik, R972, specific surface area: 90-130 m² / g; Evonik, R711, specific surface area: 125-175 m² / g.

[0080] Second type of silica: Evonik R812, specific surface area: 230-290 m² / g; Evonik R812S, specific surface area: 195-245 m² / g; Evonik R816, specific surface area: 170-210 m² / g.

[0081] Catalyst: Platinum content 0.5 wt%.

[0082] Black paste: Pinle (Shanghai) New Materials, LSR-B03.

[0083] Example 1

[0084] This embodiment provides a damming adhesive and its preparation method. The selection and dosage of each component are shown in Table 1. The adhesive is prepared according to the following method:

[0085] (1) Mix vinyl silicone oil A, crosslinked hydrogen silicone oil, first silica, second silica, tackifier A and inhibitor for 0.5 h to obtain component A;

[0086] (2) Mix vinyl silicone oil B, first silica, second silica, tackifier B, catalyst and black paste for 0.5 h to obtain component B;

[0087] (3) Mix the A component and the B component at a mass ratio of 1:1 to obtain the dam sealant.

[0088] The selection and dosage of each component in Examples 2-8 are shown in Table 1, and the preparation method is the same as in Example 1.

[0089]

[0090] Table 1

[0091] The selection and dosage of each component in Comparative Examples 1-6 are shown in Table 2, and the preparation method is the same as that in Example 1.

[0092]

[0093] Table 2

[0094] The contents of vinyl groups, silane groups, silica, and tackifiers in the examples and comparative systems are shown in Table 3.

[0095] Table 3

[0096] Performance testing:

[0097] (1) Viscosity: The dynamic viscosity (Pa·s) of the damming adhesive was measured according to GB / T 10247-2008 "Viscosity Measurement Method - Rotation Method". The shear thinning method was used, and data was taken every 6 seconds for a total of 15 data points. The rotation speed was 1 rpm for the first 5 data points, 2 rpm for the middle 5 data points, and 10 rpm for the last 5 data points. The average of the 5 data points at 10 rpm was taken as the dynamic viscosity value.

[0098] (2) Thixotropic index: The thixotropic index is calculated by dividing the dynamic viscosity value at 10 rpm by the dynamic viscosity value at 2 rpm.

[0099] (3) Density: The density was tested using a density scale.

[0100] (4) Residual adhesive rate and peeling test after curing: The adhesive application size is 2 mm wide, 0.3 mm thick, and 20 cm long. It is baked at 60 ℃ for 30 min, left to stand for 24 hours, and then the adhesive is peeled off. The adhesive is observed to see if it will break and the residual adhesive rate is measured (residual adhesive rate = mass of adhesive remaining on the substrate surface / amount of adhesive applied × 100%).

[0101] The performance of the damming adhesives provided in the examples and comparative examples was tested according to the above test methods, and the results are shown in Tables 4 and 5:

[0102] Table 4

[0103] Table 5

[0104] As shown in Tables 4 and 5, the damming adhesive provided by this invention has good thixotropy, with a thixotropic index greater than 2.5, low density, less than 5% residual adhesive after curing, and will not break when peeled off, will not cause silicone gel poisoning, has good workability and reworkability, and the residual adhesive is easy to clean.

[0105] As can be seen from the comparison between Examples 1 and Examples 7-8, the amounts of the first and second silica are within the preferred range of the present invention, resulting in better thixotropic properties of the damming adhesive and lower residual adhesive rate.

[0106] As can be seen from the comparison between Example 1 and Comparative Example 1, no tackifier was used in Comparative Example 1, which resulted in poorer thixotropic properties of the damming adhesive, increased residual adhesive rate after curing, and was not conducive to rework.

[0107] The comparison between Example 1 and Comparative Examples 2-3 shows that in Comparative Example 2, the use of only the second silica significantly improved the thixotropy of the damming adhesive, but this also led to a decrease in the strength of the damming adhesive and an increase in the rework residue rate after curing; in Comparative Example 3, the use of only the first silica reduced the thixotropy of the damming adhesive.

[0108] As can be seen from the comparison between Example 4 and Comparative Example 4, Comparative Example 4 uses cross-linked hydrosilicone oil with a high content of silane groups. Due to the high density of silane groups and the steric hindrance effect, some silane groups cannot fully react, resulting in incomplete curing and residue at the bottom, which in turn leads to an increase in the residual adhesive rate.

[0109] As can be seen from the comparison between Example 4 and Comparative Example 5, the molar ratio of silane-hydrogen groups to vinyl groups is relatively high in Comparative Example 5, the crosslinking density is too high, the damming adhesive becomes brittle, resulting in multiple breakages and affecting rework.

[0110] As can be seen from the comparison between Example 1 and Comparative Example 6, the tackifier in Comparative Example 6 does not contain acryloyloxy groups, which leads to a decrease in thixotropy.

[0111] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A type of dam-building adhesive, characterized in that, The dam-forming adhesive comprises component A and component B. Component A comprises the following components by weight: Vinyl silicone oil A 75-85 parts Crosslinked hydrosilicone oil 0.2-8 parts Silica A5-15 parts Tackifier A1 - 3 parts Inhibitor 0.01-1 part; Component B comprises the following components by weight: Vinyl silicone oil B50-60 parts 0.1-0.5 parts of silica B Tackifier B1 - 3 parts Catalyst 0.1-0.5 parts 0.1-0.5 parts color paste The tackifier A and tackifier B each independently comprise an organosilicon tackifier containing an acryloxy group; The crosslinked hydrosilicone oil contains 1-2 mmol / g of silane groups; The silica A and silica B each independently comprise a first silica and a second silica; The specific surface area of ​​the first silica is 90-190 m² / g; The specific surface area of ​​the second silica is 195-300 m² / g.

2. The dam-forming adhesive according to claim 1, characterized in that, The molar ratio of the hydroxyl groups to the vinyl groups in the crosslinked hydrosilicone oil is (0.25-0.50):

1. Based on the mass of silica A or silica B as 100%, the first silica accounts for 6-34%.

3. The dam-forming adhesive according to claim 1, characterized in that, The viscosities of vinyl silicone oil A and vinyl silicone oil B at 25°C are each independently 500-10000 cs; The vinyl content in vinyl silicone oil A and vinyl silicone oil B is independently 0.05-0.15 mmol / g.

4. The dam-forming adhesive according to claim 1, characterized in that, The viscosity of the crosslinked hydrosilicone oil at 25°C is 5-500 cs.

5. The dam-forming adhesive according to claim 1, characterized in that, The inhibitors include 2, 4, 6, and 8. Tetramethyl 2,4,6,8 Tetravinylcyclotetrasiloxane, 1,1,3,3 Tetramethyl 1,3 Divinylsiloxane, 3 methyl 1 Butyryl 3 alcohol, 1 Ethynylcyclohexanol, 3 Phenyl 1 Butyryl 3 alcohol, 3 propyl 1 Butyryl 3 alcohol, 3 Sinki 1 Butyryl 3 Any one or a combination of at least two alcohols.

6. The dam-forming adhesive according to claim 1, characterized in that, The acryloxy-containing silicone tackifier includes γ Methacryloxypropyltrimethoxysilane, 3 The combination of any one or at least two of the following: methacryloyloxypropylmethyldimethoxysilane or methacryloyloxyethyltrimethylammonium chloride copolymer.

7. The dam-forming adhesive according to claim 1, characterized in that, The catalyst includes a platinum catalyst; The platinum catalyst includes any one or a combination of at least two of the following: an alcoholic solution of chloroplatinic acid, a platinum catalyst coordinated with tetrahydrofuran, or a platinum catalyst coordinated with divinyltetramethylsiloxane. The platinum catalyst contains 4000-6000 ppm of platinum. The color paste includes black paste; The mass ratio of component A to component B is 1:(0.8-1.2).

8. The method for preparing the damming adhesive according to any one of claims 1-7, characterized in that, The preparation method includes the following steps: (1) Mix vinyl silicone oil A, crosslinked hydrosilicone oil, silica A, tackifier A and inhibitor to obtain component A; (2) Mix vinyl silicone oil B, silica B, tackifier B, catalyst and color paste to obtain component B; (3) Mix component A and component B to obtain the dam sealant.

9. The preparation method according to claim 8, characterized in that, In steps (1)-(3), the mixing time is 0.5-2 h for each step.

10. The application of the damming adhesive according to any one of claims 1-7 in a screen.

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