A low-temperature hardening-resistant silicone optical bonding adhesive and its preparation and application

Abstract

The present invention relates to a low-temperature hardening-resistant silicone optical bonding adhesive and its preparation and application, belonging to the field of adhesives. The present invention provides a low-temperature hardening-resistant silicone optical bonding adhesive, the optical bonding adhesive comprises the following raw materials: 100 parts by weight of the total mass of vinyl silicone oil + substance B, 5 to 40 parts by weight of tackifying resin, 1 to 20 parts by weight of linear polysiloxane with silane functional groups, 0.1 to 50 ppm of catalytically active substances in M, and 0.001 to 1% of polymerization inhibitor in M; the total mass of vinyl silicone oil + substance B + tackifying resin + linear polysiloxane with silane functional groups is recorded as M; the structural formula of the substance B is shown in Formula I. The silicone optical bonding adhesive obtained by the present invention is low-temperature frozen under the conditions of -60°C to -50°C, does not crystallize and harden, and has high transparency, low haze, and low yellowing index.

Description

Technical Field

[0001] The invention relates to a low-temperature hardening-resistant organic silicon optical bonding adhesive and preparation and application thereof, belonging to the field of adhesives. Background Art

[0002] Currently, commercial silicone liquid optically transparent adhesives are mainly based on the silicon-hydrogen addition system, and their curing types include light / heat dual curing and thermal curing.

[0003] With the development of 3C displays and in-vehicle displays in recent years, silicone optical bonding adhesive has been widely used in application fields such as in-vehicle and large-size commercial display screens due to its advantages over traditional acrylic optical bonding adhesive in terms of yellowing resistance, high touch sensitivity, and high and low temperature resistance.

[0004] Traditional silicone optical bonding adhesive generally has a polydimethylsiloxane main chain with a double helix structure and a regular molecular chain. When frozen at low temperature, it generally hardens at -40°C. Dynamic mechanical analysis (DMA) found that it has an obvious modulus transition near -40°C, and a second obvious modulus transition behavior at -120°C. The analysis found that the obvious modulus transition near -40°C is the crystallization behavior of polydimethylsiloxane molecules, and the second modulus transition behavior at -120°C is the glass transition of silicone.

[0005] As an optical touch screen for display, if the screen is used in extremely cold areas below -40℃, the glue will crystallize and harden, which may cause excessive internal stress on the screen surface, affecting the display effect and touch sensitivity. Therefore, it is particularly important to improve the crystallinity of traditional silicone optical bonding glue. Summary of the invention

[0006] In view of the defect that the above-mentioned existing silicone optical adhesives show obvious low-temperature crystallization and hardening phenomenon at around -40°C, the present invention partially destroys the molecular regularity of the silicone optical bonding adhesive after curing through molecular structure modification, thereby improving its low-temperature crystallization performance. It does not crystallize and harden when frozen at low temperature under conditions of -60°C to -50°C, and has high transparency, low haze and low yellowing index. In other words, an optical bonding touch screen with excellent comprehensive performance that can be used in extremely cold environment conditions at temperatures between -60°C and -50°C is provided.

[0007] The technical solution of the present invention:

[0008] The first technical problem to be solved by the present invention is to provide a low-temperature hardening-resistant silicone optical bonding adhesive, wherein the optical bonding adhesive comprises the following raw materials in the following proportions:

[0009]

[0010] Wherein, the catalytically active substance is the substance in the catalyst (substance E) that has a catalytic effect; the total mass of vinyl silicone oil + substance B + tackifying resin + linear polysiloxane having a silicon hydrogen functional group is recorded as M;

[0011] The structural formula of the substance B is shown in Formula I:

[0012]

[0013] Among them, R 1 It is an alkyl, aryl or aralkyl group having 2 to 20 carbon atoms except for methyl, or a functional group containing an oxygen heteroatom; and 150≤(y+z)≤2000, 0.03≤z / (y+z)≤0.2. Preferably, 200≤(y+z)≤1000.

[0014] Furthermore, the R 1 It is an alkyl group having 3 to 12 carbon atoms, phenyl, naphthyl, benzyl, phenethyl, methacryloxypropyl, 3-(2,3-epoxypropyloxy)propyl or 2-(3,4-epoxycyclohexane)ethyl, etc.; preferably, hexyl, octyl or phenyl.

[0015] Furthermore, the mass ratio of the vinyl silicone oil to the substance B is: 10-90:90-10; preferably 30-80:70-20; more preferably 50-80:50-20.

[0016] Preferably, the added amount of the tackifying resin is 10 to 20 parts by weight.

[0017] Preferably, the catalytically active substance accounts for 1 to 10 ppm of M.

[0018] Preferably, the inhibitor accounts for 0.01-0.2% of M.

[0019] Further, the substance B is prepared by the following method: a monomer containing dimethyl dihydrolysis functionality is reacted with a monomer containing R 1 and a monomer containing dihydrolysis functionality of methyl (the ratio of the two is such that the following is satisfied in formula I: 0.03≤z / (y+z)≤0.2), after co-hydrolysis under acidic or alkaline conditions, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane and a catalytic substance are added, and the substance B is obtained by a balanced condensation reaction; wherein the monomer containing dimethyl dihydrolysis functionality and the monomer containing R 1 The ratio of the monomers with dihydrolysis functionality of methyl groups is such that the following is satisfied in Formula I: 0.03≤z / (y+z)≤0.2. The present invention utilizes substance B for the first time to reduce the crystallization temperature of the organic silicon optical bonding adhesive.

[0020] Furthermore, in the preparation method of the substance B, the monomer containing dimethyl dihydrolysis functionality is selected from: dimethyldimethoxysilane or dimethyldiethoxysilane.

[0021] Furthermore, in the preparation method of the above-mentioned substance B, the R 1 The dihydrolyzed functional monomer having a methyl group is selected from: methylphenyldimethoxysilane, methylphenyldiethoxysilane, methylhexyldimethoxysilane, methylhexyldiethoxysilane, methyloctyldimethoxysilane or methyloctyldiethoxysilane, etc.

[0022] Furthermore, in the preparation method of the above substance B, the catalytic substance is selected from: one of tetramethylammonium hydroxide or its siliconate, potassium hydroxide, lithium hydroxide or tetrabutylphosphonium hydroxide.

[0023] Furthermore, the linear polysiloxane having a silicon-hydrogen functional group (substance D—i.e., terminal hydrogen-containing silicone oil and / or side hydrogen-containing silicone oil) has a structural formula of Formula II and / or Formula III:

[0024]

[0025] In formula II, 10≤o≤45; in formula III, 20≤p+q≤80, 0.2≤q / (p+q)≤0.6.

[0026] Furthermore, the linear polysiloxane having a silicon-hydrogen functional group (substance D) is a mixture of substances represented by formula II and formula III, wherein the mass ratio of the substance represented by formula II to the substance represented by formula III in the mixture is 5-95:95-5, preferably 70-90:30-10.

[0027] Furthermore, in the linear polysiloxane having a silicon-hydrogen functional group, the molar ratio of the silicon-hydrogen functional group (Si-H) in Formula II and Formula III to the terminal vinyl functional group (Si-Vi) of the vinyl silicone oil and substance B is 0.5 to 0.9.

[0028] Furthermore, the structure of the vinyl silicone oil is shown in Formula IV:

[0029]

[0030] In formula IV, Vi represents a vinyl group, m is an integer of 150 to 2000, and n is an integer of 0 to 30. (m+n) is in the above range so that the viscosity of the vinyl polysiloxane at room temperature 25°C satisfies the requirement of 300 to 200,000 mPa.s; when n=0, the vinyl polysiloxane represented by (I) is a terminal vinyl polysiloxane, and when n is an integer greater than 0, the vinyl polysiloxane represented by (I) is a side-terminated vinyl polysiloxane.

[0031] Further, the tackifying resin (substance C) is a material having a structure of (R 2 3SiO 0.5 ) a (SiO2) d The MQ resin shown, where R 2 Containing C1~C 10 An alkyl group (such as methyl, ethyl, propyl) or an aryl group containing a benzene ring; preferably R 2 All of them are methyl, that is, the tackifying resin is methyl MQ resin.

[0032] Furthermore, the catalyst (substance E) is a metal compound or complex having hydrosilylation catalytic activity.

[0033] Preferably, the catalyst is selected from metal complexes of platinum, palladium, rhodium, etc., preferably a platinum metal complex.

[0034] More preferably, the catalyst is selected from: chloroplatinic acid, a complex of chloroplatinic acid and isopropanol, a complex of chloroplatinic acid and divinyltetramethyldisiloxane or a complex of chloroplatinic acid and 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane, preferably a complex of chloroplatinic acid and divinyltetramethyldisiloxane, i.e., a Karstedt catalyst; a compound containing Pt and having a conjugated olefin structure, such as trimethyl(methylcyclopentadienyl)platinum(IV) and di(acetylacetonate)platinum(II); preferably, a Karstedt catalyst having a thermosensitive catalytic activity.

[0035] Furthermore, the polymerization inhibitor (substance F) is at least one of 1-ethynyl-1-cyclohexanol, 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane, etc.; preferably 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane.

[0036] The second technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned low-temperature resistant and hardening silicone optical bonding adhesive, wherein the preparation method is as follows: the above-mentioned raw materials are evenly blended to obtain the silicone optical bonding adhesive.

[0037] Furthermore, the preparation method of the above-mentioned low temperature resistant hardening organic silicone optical bonding adhesive is:

[0038] Method 1: Preparation of two-component low-temperature resistant optical adhesive:

[0039] Vinyl silicone oil (substance A), substance B and tackifying resin (substance C) are pre-dispersed and mixed uniformly to prepare a basic rubber material, a portion of the basic rubber material is mixed with a catalyst (substance E) and a polymerization inhibitor (substance F) to prepare component A; the remaining basic rubber material is mixed with a linear polysiloxane having a silicon hydrogen functional group (substance D) to prepare component B; when used, components A and B are mixed uniformly and bubbles are removed; the basic rubber material in component A and the basic rubber material in component B are blended in any proportion;

[0040] Method 2: Preparation of single-component low-temperature resistant optical adhesive:

[0041] The vinyl silicone oil, substance B and tackifying resin are pre-dispersed, and then a catalyst and an inhibitor are added and stirred and mixed. Then, a linear polysiloxane having a silicon hydrogen functional group is added and stirred and mixed. Finally, the organic silicone optical bonding adhesive is obtained by filtering and packaging.

[0042] Furthermore, in the above method 1 or method 2, pre-dispersion or stirring refers to stirring at a stirring speed of 30 to 35 Hz for 10 to 30 minutes.

[0043] Furthermore, in the above method 1, the mixing ratio of component A and component B can be adjusted according to the reaction molar ratio of Si-H and Si-Vi, preferably 1:1 to 4:1, more preferably 1:1.

[0044] Furthermore, in the above method 1, components A and B are mixed evenly and can be used after removing bubbles.

[0045] The third technical problem to be solved by the present invention is to point out that the above-mentioned low-temperature resistant and hardening silicone optical bonding adhesive is used in display screens, touch screens and other optical devices.

[0046] Beneficial effects of the present invention:

[0047] The present invention provides a low-temperature hardening organic silicon optical bonding adhesive and its preparation and application. The organic silicon optical bonding adhesive can be used for touch screen bonding. Compared with traditional organic silicon optical bonding adhesives, the cured product has a lower crystallization temperature, and will not crystallize and harden when low-temperature frozen under the conditions of -60℃ to -50℃. It has high transparency, low haze, and low yellowing index, and can be used for optical bonding touch screens in extremely cold environments with temperatures of -60℃ to -50℃. The low-temperature hardening organic silicon optical bonding adhesive provided by the present invention can be activated by light or cured by heating, and is mainly used for bonding between substrates and cover plates of display screens, touch screens, and other optical devices, and can meet processes such as scraping glue, dispensing glue, scraping glue, and slit coating, and can be used in extremely cold environments with temperatures of -60℃ to -50℃. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1DMA modulus curves of Example 3, Example 7 and Comparative Example 3. DETAILED DESCRIPTION

[0049] The present invention provides a low temperature resistant hardening organic silicon optical bonding adhesive, which mainly comprises:

[0050] Substance A: vinyl silicone oil (such as polydimethylsiloxane with terminal vinyl groups);

[0051] Substance B: Compared to vinyl-terminated polysiloxane in which some methyl groups are replaced by other functional groups;

[0052] Substance C: tackifying resin;

[0053] Substance D: linear polysiloxane with silyl hydride functional groups;

[0054] Substance E: catalyst;

[0055] Substance F: inhibitor.

[0056] The preparation of substance A is well known to the industry. It is generally obtained by ring-opening polymerization of dimethylsiloxane cyclopolymer (DMC) and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane under the catalysis of tetramethylammonium hydroxide silicon alkoxide, heating to break the enzyme, decomposing the catalyst and removing low molecular weight. It can also be obtained through commercial channels, such as the RH-Vi series vinyl silicone oil of Ningbo Runhe High-tech Materials Technology Co., Ltd. and the V series vinyl silicone oil.

[0057] Substance B is a vinyl-terminated polysiloxane in which some methyl groups are replaced by other functional groups, and its structure is shown below:

[0058]

[0059] Where R 1 is the other functional group of the substituted methyl group, R 1 It can be other alkyl groups except methyl, such as alkyl groups with 2 to 20 carbon atoms, preferably alkyl groups with 3 to 12 carbon atoms, preferably hexyl, octyl, etc.; R 1 It can also be an aryl group or an aralkyl group, such as phenyl, naphthyl, benzyl, phenethyl, etc., preferably phenyl. 1 It may also be a functional group containing an oxygen heteroatom, such as methacryloyloxypropyl, 3-(2,3-epoxypropyloxy)propyl, 2-(3,4-epoxycyclohexane)ethyl, and the like.

[0060] The values ​​of y and z in the substance B satisfy 150≤(y+z)≤2000, preferably 200≤(y+z)≤1000, 0.03≤z / (y+z)≤0.2, so that the viscosity of substance B is 300mPa.s-35000mPa.s at 25°C, and the refractive index of substance B at 25°C is 1.41-1.44. If z / (y+z)<0.03, (B) cannot effectively destroy the regularity of the molecular chain segments of the cured product, and the product is easy to crystallize when frozen at -60°C to -50°C; if z / (y+z)>0.2, the refractive index of (B) may be greater than 1.44, and fogging may occur after the mixture of substance A and substance B due to the difference in refractive index and polarity, which affects the transparency and haze of the cured product.

[0061] Substance C is a tackifying resin, an MQ resin having the structure shown below:

[0062] (R 2 3SiO 0.5 ) a (SiO2) d

[0063] Among them, 30≤a≤45, 15≤d≤50, a:d=0.6~0.9:1, R 2 Containing C1~C 10 Alkyl groups such as methyl, ethyl, propyl or aromatic groups containing benzene rings, preferably R 2 All of them are methyl groups, that is, substance C is methyl MQ resin.

[0064] The preparation method of substance C is well known to industry practitioners, such as the preparation by water glass method according to patent US 2676182 or the preparation by orthosilicate method according to the description of patent US 4774310 or patent CN 102775612A. It can also be obtained from commercial brands, such as XJY-8205 of Jiangxi Xinjiayi New Materials Co., Ltd. and DY-MQ102N of Shandong Dayi Chemical Co., Ltd.

[0065] The content of substance C is 5 to 40 parts, preferably 10 to 20 parts, relative to 100 parts by weight of the composition of substance A and substance B. The addition of substance C can improve the adhesion of the cured product to substrates such as glass, PC, etc. and enhance the adhesion.

[0066] Substance D is a linear polysiloxane having a silicon-hydrogen functional group, and its structure includes the following two structures (D-1) and / or (D-2);

[0067]

[0068] In (D-1), o satisfies 10≤o≤45. (D-1) is commonly known as terminal hydrogen-containing silicone oil in the silicone industry. It mainly plays the role of improving the toughness of the cured product and increasing the elongation. If o<10, although (D-1) can enhance toughness during the reaction, it is also easy to volatilize when heated, which is not conducive to the reliability of the display screen. If o>45, the reactive functional groups are too few and the activity is low, then (D-1) cannot play a good role in enhancing toughness.

[0069] In (D-2), p and q satisfy 20≤p+q≤80, 0.2≤q / (p+q)≤0.6. (D-2) is commonly known as side hydrogen-containing silicone oil in the silicone industry. If p+q<20, (D-2) is easy to volatilize when heated, which is not conducive to the reliability of the display screen. If p+q>80, (D-2) has too high viscosity, slow reaction activity and slow curing speed. If q / (p+q)<0.2, the content of silicon hydrogen functional groups is low and it is not easy to cure and crosslink. If q / (p+q)>0.8, the content of silicon hydrogen functional groups is too high, and bubbles are easy to appear in the glue layer after high-temperature reliability aging, affecting the visual effect.

[0070] Preferably, the substance D is composed of (D-1) and (D-2), and compared with 100 parts by weight of the composition of substance A and substance B, the total amount of (D-1) and (D-2) is 1 to 20 parts, and the molar ratio of the silicon hydride functional group (Si-H) in (D-1) and (D-2) to the terminal vinyl functional group (Si-Vi) of substance A and substance B is 0.5 to 0.9. In 100 parts of the mixture (D) composed of (D-1) and (D-2), the ratio of (D-1) to (D-2) is 5 to 95:95 to 5, preferably 70 to 90:30 to 10.

[0071] The preparation methods of (D-1) and (D-2) are also well known to industry practitioners, and both can be obtained through related balanced ring-opening reactions. They can also be obtained through commercial channels, such as the RH-H series silicone oil of Ningbo Runhe High-tech Materials Technology Co., Ltd., and the D series and SH series of Jiangsu Kexing New Materials Co., Ltd.

[0072] Catalyst E is a metal compound or complex with catalytic activity of hydrosilylation, such as a metal complex of platinum, palladium, rhodium, etc., preferably a metal complex of platinum. The above catalyst has heat-sensitive and photosensitive activity, and can rapidly catalyze the hydrosilylation reaction after heating or light activation. Among them, the catalyst with heat-sensitive catalytic activity has chloroplatinic acid, a complex of chloroplatinic acid and isopropanol, a complex of chloroplatinic acid and divinyltetramethyldisiloxane, or a complex of chloroplatinic acid and 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane, preferably a complex of chloroplatinic acid and divinyltetramethyldisiloxane, i.e., a Karstedt catalyst. The catalyst with photosensitive activity is a compound containing Pt and having a conjugated olefin structure, such as trimethyl (methylcyclopentadienyl) platinum (IV) and di (acetylacetone) platinum (II), etc. The above catalyst preferably has a Karstedt catalyst with heat-sensitive catalytic activity.

[0073] The polymerization inhibitor F is one or more of 1-ethynyl-1-cyclohexanol, 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane, etc., preferably 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane.

[0074] The present invention provides a low-temperature hardening-resistant silicone optical bonding adhesive, which is packaged in a single-component or two-component form, preferably a two-component form. When packaged as a two-component adhesive, substance A, substance B, and substance C can be pre-mixed and uniformly prepared into a basic adhesive, a portion of the above-mentioned basic adhesive is mixed with substance E and substance F to prepare component A, and the remaining part of the above-mentioned basic adhesive is mixed with substance D to prepare component B. When used, components A and B are mixed uniformly and can be used after removing bubbles. The mixing ratio of components A and B can be adjusted according to the reaction molar ratio of Si-H and Si-Vi, preferably 1:1 to 4:1, and more preferably 1:1.

[0075] The specific implementation modes of the present invention are further described below in conjunction with embodiments, but the present invention is not limited to the scope of the embodiments.

[0076] Example 1 Preparation of phenyl-substituted vinyl-terminated polysiloxane B1:

[0077] In a 10L four-necked flask with stirring, condensing and reflux water separation devices, 3600g of deionized water and 12.5g of potassium hydroxide were added, and the reaction temperature was set to 80°C. When the material temperature reached 45°C, 273g of methylphenyldimethoxysilane and 2832g of dimethyldimethoxysilane were added, and the reaction was refluxed at 70-80°C for 2h. After adding 2000g of toluene for extraction, the temperature was raised to the reflux temperature, and the alcohol generated by the reaction was gradually separated. Finally, the temperature was lowered and the layers were allowed to stand to separate, and the upper layer of hydrolyzate clear liquid was obtained. The toluene liquid was washed with water 2-3 times until it was neutral.

[0078] The above hydrolysis product is heated, the oil temperature is set to 120°C, and toluene is removed by reduced pressure distillation. 18.6g of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane and 1g of tetramethylammonium hydroxide are added to the above product, and a balanced condensation reaction is carried out at 100-110°C for 4h. Then the temperature is raised to 160°C to decompose tetramethyl sodium hydroxide, and low molecular weight is removed under reduced pressure to obtain the substance B of the present invention. In B, z=15, y=236, z / (y+z)=0.06, the viscosity is 1380mPa.s, the refractive index at 25°C is 1.4180, and the vinyl content is 0.27wt%.

[0079] Comparative Example 1 Preparation of phenyl-substituted vinyl-terminated polysiloxane B2:

[0080] In a 10L four-necked flask with stirring, condensing and reflux water separation devices, 3600g of deionized water and 12.5g of potassium hydroxide were added, and the reaction temperature was set to 80°C. When the material temperature reached 45°C, 1005g of methylphenyldimethoxysilane and 2349g of dimethyldimethoxysilane were added, and the reaction was refluxed at 70-80°C for 2h. After adding 2000g of toluene for extraction, the temperature was raised to the reflux temperature, and the alcohol generated by the reaction was gradually separated. Finally, the temperature was lowered and the layers were allowed to stand to separate, and the upper layer of hydrolyzate clear liquid was obtained. The toluene liquid was washed with water 2-3 times until it was neutral.

[0081] The above hydrolysis product was heated, the oil temperature was set to 120°C, and toluene was removed by reduced pressure distillation. 18.6g of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane and 1g of tetramethylammonium hydroxide were added to the above product, and the equilibrium condensation reaction was carried out at 100-110°C for 4h. Then the temperature was raised to 160°C to decompose tetramethyl sodium hydroxide, and low molecular weight was removed under reduced pressure to obtain substance B-terminated vinyl polysiloxane, in which z=55.22, y=195.78, z / (y+z)=0.22, viscosity was 2000mPa.s, refractive index was 1.4510 at 25°C, and vinyl content was 0.24%.

[0082] Comparative Example 2 Preparation of phenyl-substituted vinyl-terminated polysiloxane B3:

[0083] In a 10L four-necked flask with stirring, condensing and reflux water separation devices, 3600g of deionized water and 12.5g of potassium hydroxide were added, and the reaction temperature was set to 80°C. When the material temperature reached 45°C, 46g of methylphenyldimethoxysilane and 3000g of dimethyldimethoxysilane were added. The reaction was refluxed at 70-80°C for 2h, and 2000g of toluene was added for extraction. The temperature was raised to the reflux temperature, and the alcohol generated by the reaction was gradually separated. Finally, the temperature was lowered and the layers were allowed to stand to separate, and the upper layer of hydrolyzate was obtained. The toluene liquid was washed with water 2-3 times until it was neutral.

[0084] The above hydrolysis product was heated, the oil temperature was set to 120°C, and toluene was removed by reduced pressure distillation. 18.6g of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane and 1g of tetramethylammonium hydroxide were added to the above product, and the condensation reaction was balanced at 100-110°C for 4h. Then the temperature was raised to 160°C to decompose tetramethyl sodium hydroxide, and low molecular weight was removed under reduced pressure to obtain substance B-terminated vinyl polysiloxane, in which z=2.56, y=250, z / (y+z)=0.01, viscosity was 1410mPa.s, refractive index was 1.4092 at 25°C, and vinyl content was 0.22wt%.

[0085] Example 2 Preparation of alkyl-substituted vinyl-terminated polysiloxane B4:

[0086] In a 10L four-necked flask with stirring, condensing and reflux water separation devices, 3600g of deionized water and 12.5g of potassium hydroxide were added, and the reaction temperature was set to 80°C. When the material temperature reached 45°C, 557g of octylmethyldimethoxysilane and 2760g of dimethyldimethoxysilane were added, and the reaction was refluxed at 70-80°C for 2h. After adding 2000g of toluene for extraction, the temperature was raised to reflux temperature, and the alcohol generated by the reaction was gradually separated. Finally, the temperature was lowered and allowed to stand for stratification to obtain the upper layer of hydrolyzate clear liquid, and the toluene liquid was washed with water 2-3 times until it was neutral.

[0087] The above hydrolysis product was heated, the oil temperature was set to 120°C, and toluene was removed by reduced pressure distillation. 18.6g 1,3-divinyl-1,1,3,3-tetramethyldisiloxane and 1g tetramethylammonium hydroxide were added to the above product, and the condensation reaction was balanced at 100-110°C for 4h. Then the temperature was raised to 160°C to decompose tetramethyl sodium hydroxide, and low molecular weight was removed under reduced pressure to obtain substance B-terminated vinyl polysiloxane, in which z=2.56, y=230, z / (y+z)=0.1, viscosity was 1220mPa.s, refractive index was 1.4172 at 25°C, and vinyl content was 0.21wt%.

[0088] Preparation of low temperature resistant optical adhesive in Examples 3 to 7:

[0089] 1) Raw materials used:

[0090] Material A - polydimethylsiloxane with terminal vinyl groups (vinyl silicone oil):

[0091] A 1——RH-Vi301, Ningbo Runhe High-tech Materials Technology Co., Ltd., viscosity 100000mPa.s, vinyl content 0.06wt.%;

[0092] A2——RH-Vi1320, Ningbo Runhe High-tech Materials Technology Co., Ltd., viscosity 2000mPa.s, vinyl content 0.23wt.%;

[0093] A3——RH-Vi311, Ningbo Runhe High-tech Materials Technology Co., Ltd., viscosity 500mPa.s, vinyl content 0.43wt.%;

[0094] Substance B-phenyl or alkyl substituted vinyl-terminated polysiloxane:

[0095] B1——prepared in Example 1 of the present invention;

[0096] B 2——prepared in Comparative Example 1 of the present invention;

[0097] B 3——prepared in Comparative Example 2 of the present invention;

[0098] B 4——prepared in Example 2 of the present invention.

[0099] Substance C - Tackifying Resin C - Methyl MQ resin brand XJY-8205 from Jiangxi Xinjiayi New Materials Co., Ltd.

[0100] Substance D - Linear polysiloxane with silicon-hydrogen functional groups (terminal hydrogen-containing silicone oil):

[0101] (D-1)——end hydrogen-containing silicone oil, D-15, Jiangsu Kexing New Materials Co., Ltd., viscosity 15mPa.s, hydrogen content 0.12%; (D-2)——side hydrogen-containing silicone oil, SH-50, Jiangsu Kexing New Materials Co., Ltd., viscosity 50mPa.s, hydrogen content 0.5%;

[0102] Material E - Catalyst - Karstedt catalyst (Pt-5000) with a Pt content of 5000 ppm prepared by Shanghai Heraeus Industrial Technology Materials Co., Ltd.

[0103] Substance F - Inhibitor - 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane (ViD4) with a purity of ≥95% prepared by Zhejiang Quzhou Jiancheng Silicone Co., Ltd.

[0104] 2) Preparation method:

[0105] After the above raw materials are uniformly mixed according to the proportion composition in Table 1, light-curing silicone LOCA is prepared. The preparation process is as follows: using a planetary stirring kettle, first put material A, material B and material C into a planetary stirring kettle and stir at high speed (stirring speed 30-35Hz) for 10min for pre-dispersion, then add material E and material F and stir at high speed (stirring speed 30-35Hz) for 20min, then add material D and stir at high speed (stirring speed 30-35Hz) for 30min, filter and package it into a single-component low-temperature resistant optical adhesive, and perform performance testing after curing; the raw material proportions of each embodiment are shown in Table 1.

[0106] 3) Performance testing:

[0107] Test method: The viscosity is the viscosity tested at 25°C using a Brookfield DVS+ viscometer; the transmittance and haze are tested using a BYK 4775 projection haze meter; the yellowing index is tested using a Shimadzu UV2600I ultraviolet visible spectrophotometer; the crystallization temperature is tested using a TA DMA850 dynamic analyzer. The performance of each embodiment and comparative example is shown in Table 2.

[0108] Comparative Examples 3 to 5 Preparation of Silicone Optical Bonding Adhesives:

[0109] The preparation method is the same as that of Example 3-7, and the raw material ratio is shown in Table 1; the performance results are shown in Table 2.

[0110] Table 1 Raw materials in Examples 3 to 7 and Comparative Examples 3 to 5 (parts by weight)

[0111]

[0112] In the table, Pt-5000 means that the Pt content is 5000 ppm.

[0113] Table 2 Performance results of the optical adhesives obtained in Examples 3 to 7 and Comparative Examples 3 to 5

[0114]

[0115] It can be seen from the data in Table 2 that the organic silicone optical bonding adhesive prepared according to the present invention has a lower crystallization temperature than the conventional fully methyl structured polydimethylsiloxane optical bonding adhesive, does not harden after being frozen at -55°C for 96 hours, and has excellent low temperature resistance. At the same time, after the introduction of other functional groups that replace the methyl group, it has good compatibility with conventional polydimethylsiloxane polymers, high transparency, low haze, and yellowing resistance, and can be used in optically bonded touch screens used in extreme low temperature environments. The DMA modulus curves of Example 3 and Example 7 are the same as those of Comparative Example 3. Figure 1As shown, after the introduction of phenyl-substituted terminal vinyl polysiloxane, the crystallization temperature decreased from -44.94°C to -57.26°C, and after the introduction of octyl-substituted terminal vinyl polysiloxane, the crystallization temperature decreased from -44.94°C to -55.41°C.

[0116] The description of the present invention is considered to be illustrative rather than restrictive. Based on the present invention, those skilled in the art can make some substitutions and modifications to some of the technical features according to the disclosed technical content without creative labor, all of which are within the protection scope of the present invention.

Claims

1. A low temperature resistant hardening organic silicon optical bonding adhesive, characterized in that: The optical bonding adhesive comprises raw materials in the following proportions: Wherein, the total mass of vinyl silicone oil + substance B + tackifying resin + linear polysiloxane with silicon hydrogen functional group is recorded as M; the catalytic active substance is the substance in the catalyst that plays a catalytic role; The structural formula of the substance B is shown in Formula I: In Formula I, R 1 It is an alkyl group, an aryl group or an aralkyl group having 2 to 20 carbon atoms except a methyl group, or a functional group containing an oxygen heteroatom; and 150≤(y+z)≤2000, 0.03≤z / (y+z)≤0.2; The linear polysiloxane having a silicon hydrogen functional group is a substance represented by Formula II and / or Formula III: In formula II, 10≤o≤45; in formula III, 20≤p+q≤80, 0.2≤q / (p+q)≤0.6; The structural formula of the vinyl silicone oil is shown in Formula IV: In formula IV, Vi represents a vinyl group, m is an integer of 150-2000, and n is an integer of 0-30.

2. The low temperature hardening resistant silicone optical bonding adhesive according to claim 1, characterized in that: The R 1 It is an alkyl group having 3 to 12 carbon atoms, a phenyl group, a naphthyl group, a benzyl group, a phenethyl group, a methacryloxypropyl group, a 3-(2,3-epoxypropyloxy)propyl group or a 2-(3,4-epoxycyclohexane)ethyl group.

3. The low temperature hardening resistant silicone optical bonding adhesive according to claim 2, characterized in that: The R 1 It is hexyl, octyl or phenyl.

4. The low temperature hardening resistant silicone optical bonding adhesive according to claim 1 or 2, characterized in that: The mass ratio of vinyl silicone oil to substance B is: 10-90:90-10; and / or: The amount of the tackifying resin added is 10 to 20 parts by weight; and / or: The catalytically active substance accounts for 1 to 10 ppm of M; and / or: The inhibitor accounts for 0.01-0.2% of M.

5. The low temperature hardening resistant silicone optical bonding adhesive according to claim 4, characterized in that: The mass ratio of vinyl silicone oil to substance B is: 30-80:70-20.

6. The low temperature hardening resistant silicone optical bonding adhesive according to claim 5, characterized in that: The mass ratio of vinyl silicone oil to substance B is: 50-80:50-20.

7. The low temperature hardening resistant silicone optical bonding adhesive according to any one of claims 1 to 3, characterized in that: The substance B is prepared by the following method: a monomer containing dimethyl dihydrolysis functionality is reacted with a monomer containing R 1 and a monomer containing dihydrolysis functionality of methyl, and after co-hydrolysis under acidic or alkaline conditions, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane and a catalytic substance are added to obtain the substance B through a balanced condensation reaction; wherein the monomer containing dimethyl dihydrolysis functionality and the monomer containing R 1 The ratio of the monomers with dihydrolysis functionality of methyl groups is such that the following is satisfied in formula I: 0.03≤z / (y+z)≤0.2; The monomer containing dimethyl dihydrolysis functionality is selected from: dimethyldimethoxysilane or dimethyldiethoxysilane; and / or: The R 1 and a dihydrolyzed functional monomer having a methyl group selected from the group consisting of methylphenyldimethoxysilane, methylphenyldiethoxysilane, methylhexyldimethoxysilane, methylhexyldiethoxysilane, methyloctyldimethoxysilane or methyloctyldiethoxysilane; and / or: The catalytic substance is selected from: one of tetramethylammonium hydroxide or its silicon alkoxide, potassium hydroxide, lithium hydroxide or tetrabutylphosphonium hydroxide.

8. The low temperature hardening resistant silicone optical bonding adhesive according to any one of claims 1 to 3, characterized in that: The linear polysiloxane having a silicon hydrogen functional group is a mixture of substances represented by formula II and formula III, wherein the mass ratio of the substance represented by formula II to the substance represented by formula III in the mixture is 5-95:95-5; and / or: In the linear polysiloxane having silicon hydride functional groups, the molar ratio of silicon hydride functional groups in formula II and formula III to the terminal vinyl functional groups of the vinyl silicone oil and substance B is 0.5 to 0.

9.

9. The low temperature hardening resistant silicone optical bonding adhesive according to claim 8, characterized in that: The mass ratio of the substance represented by formula II to the substance represented by formula III in the mixture is 70-90:30-10.

10. The low temperature hardening resistant silicone optical bonding adhesive according to any one of claims 1 to 3, characterized in that: The tackifying resin is (R 2 3SiO 0.5 ) a (SiO2) d The MQ resin shown, wherein 30≤a≤45, 15≤d≤50, a:d=0.6~0.9:1, R 2 Containing C1~C 10 An alkyl group or an aryl group containing a benzene ring; and / or: The catalyst is a metal compound or complex having hydrosilylation catalytic activity; and / or: The polymerization inhibitor is at least one of 1-ethynyl-1-cyclohexanol, 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol or 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane.

11. The low temperature hardening resistant silicone optical bonding adhesive according to claim 10, characterized in that: The R 2 The catalyst is selected from the group consisting of platinum, palladium and rhodium metal complexes.

12. The low temperature hardening resistant silicone optical bonding adhesive according to claim 11, characterized in that: The catalyst is selected from: chloroplatinic acid, a complex of chloroplatinic acid and isopropanol, a complex of chloroplatinic acid and divinyltetramethyldisiloxane, or a complex of chloroplatinic acid and 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane.

13. The low temperature hardening resistant silicone optical bonding adhesive according to claim 12, characterized in that: The catalyst is selected from Karstedt catalyst.

14. The method for preparing a low temperature hardening resistant silicone optical bonding adhesive according to any one of claims 1 to 13, characterized in that: The preparation method is: the raw materials are mixed evenly to obtain the organic silicon optical bonding adhesive.

15. The method for preparing a low temperature hardening resistant silicone optical bonding adhesive according to claim 14, characterized in that: The preparation method of the low temperature resistant hardening organic silicon optical bonding adhesive is one of the following methods: Method 1: Preparation of two-component low-temperature resistant optical adhesive: Pre-disperse and mix vinyl silicone oil, substance B and tackifying resin to prepare a base rubber, take a part of the base rubber, stir and mix with a catalyst and a polymerization inhibitor to prepare component A; stir and mix the remaining base rubber with a linear polysiloxane having a silicon hydrogen functional group to prepare component B; when using, mix components A and B evenly and remove bubbles; Method 2: Preparation of single-component low-temperature resistant optical adhesive: The vinyl silicone oil, substance B and tackifying resin are pre-dispersed, and then a catalyst and an inhibitor are added and stirred and mixed. Then, a linear polysiloxane having a silicon hydrogen functional group is added and stirred and mixed. Finally, the organic silicone optical bonding adhesive is obtained by filtering and packaging.

16. The method for preparing a low temperature hardening resistant silicone optical bonding adhesive according to claim 15, characterized in that: In the method 1 or the method 2, the pre-dispersion or stirring refers to stirring at a stirring speed of 30 to 35 Hz for 10 to 30 minutes; In the method 1, the mixing ratio of component A and component B is adjusted according to the reaction molar ratio of Si-H and Si-Vi, and the reaction molar ratio of Si-H and Si-Vi is 1:1 to 4:

1.

17. The method for preparing a low temperature hardening resistant silicone optical bonding adhesive according to claim 16, characterized in that: In the method 1, the mixing ratio of components A and B is adjusted according to the reaction molar ratio of Si-H and Si-Vi, and the reaction molar ratio of Si-H and Si-Vi is 1:

1.

18. A low-temperature hardening-resistant silicone optical bonding adhesive is used in display screens, touch screens and other optical devices, wherein the low-temperature hardening-resistant silicone optical bonding adhesive is the bonding adhesive described in any one of claims 1 to 13, or the bonding adhesive prepared by the method described in any one of claims 14 to 17.

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