A silane anchoring agent, its preparation method and application

Abstract

The present application relates to a kind of silane anchoring agent, its structural formula is as shown in formula I, wherein, n is integer, 1≤n≤10;R1It indicates methyl, hydroxyl, methoxy or ethoxy;R2It indicates hydrogen, methyl or ethyl;R3It indicates γ-(2, 3-epoxypropoxy) propyl or β-(3, 4-epoxycyclohexyl) ethyl;R4It indicates hydrogen, methyl, acetoxy or R5It indicates vinyl, allyl, alkyld. Anchoring agent in the present application is the silane-based polymer with more epoxy group in side group, and it is low branched, not excessively crosslinked structure, so it can play good anchoring effect.Different from physical blending, epoxy group and alkenyl in the silane anchoring agent in the present application are in the molecular chain of polymer, so it is better compatible with pressure sensitive adhesive system and release agent system;At the same time, there is no irritating odor problem of small molecule anchoring agent.

Description

Technical Field

[0001] The present invention belongs to the technical field of anchoring agents, and in particular relates to a silane anchoring agent and a preparation method and application thereof. Background Art

[0002] Silane anchoring agents are mainly used in silicone pressure-sensitive adhesives and release agents to improve the adhesion of the coating to the substrate, enhance the adhesion of the coating, and protect the adhesive layer from being contaminated or sticking to other objects and becoming ineffective.

[0003] Chinese patent CN105295414A discloses a method for preparing an anchoring agent, wherein the anchoring agent is prepared by mixing γ-(2,3-epoxypropoxy)propyltrimethylsilane or γ-(2,3-epoxypropoxy)propyltrimethoxysilane, vinyltriacetoxysilane, and an ionic resin in a certain proportion.

[0004] Chinese patent CN106916309A discloses a tackifier for addition-type silicone pressure-sensitive adhesive. The method comprises adding γ-(2,3-epoxypropoxy)propyltrimethoxysilane, vinyltriacetoxysilane, and anhydrous aluminum chloride into a reactor in proportion, reacting the reactor, vacuumizing the reactor, and collecting the product.

[0005] The silane anchoring agents obtained by the above two methods are mostly small molecular structures. Since there are a large number of methoxy groups that do not participate in the reaction in the system, a large amount of methanol is released during use, which is not environmentally friendly.

[0006] Chinese patent CN114196021A discloses an anchoring agent and its preparation method and application. The method is to prepare the anchoring agent by using a hydroxy-terminated polysiloxane containing a vinyl functional group and an organic siloxane monomer, a lithium catalyst, and an organic solvent.

[0007] The method adopted in this patent is that the first step of hydrolysis uses an alkaline catalyst for hydrolysis. After the reaction is completed, it is necessary to obtain end-hydroxy polysiloxane by neutralization, degassing, drying, and filtering. The second step also requires the use of a lithium catalyst, which also requires neutralization, degassing, drying, and filtering. The entire reaction process is relatively complicated. Summary of the Invention

[0008] To address the aforementioned issues in the prior art, the present invention provides a silane anchoring agent and a method for preparing the same. The silane anchoring agent exhibits excellent compatibility with the organosilicon system used in pressure-sensitive adhesives and release agents. Furthermore, the silane anchoring agent exhibits strong interaction with substrates, enhancing the adhesion of the organosilicon system to the substrate. Specifically, the silane anchoring agent effectively anchors the pressure-sensitive adhesive and release agent, meeting their application requirements. Furthermore, the preparation process of the present invention boasts high raw material utilization, a simple and environmentally friendly process.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] A silane anchoring agent, the structural formula of which is shown in the following formula I:

[0011]

[0012] Where n is an integer, 1≤n≤10;

[0013] R1 represents methyl, hydroxy, methoxy or ethoxy;

[0014] R2 represents hydrogen, methyl or ethyl;

[0015] R3 represents γ-(2,3-epoxypropyloxy)propyl or β-(3,4-epoxycyclohexyl)ethyl;

[0016] R4 represents hydrogen, methyl, acetoxy or

[0017] R5 represents vinyl, allyl or butyl.

[0018] Preferably, the structural formula of the silane anchoring agent is shown in Formula II below:

[0019]

[0020] wherein Ra represents a hydroxyl group or a methoxy group; R3 is the same as in formula I; and 2≤n≤5.

[0021] The present invention also provides a method for preparing the above-mentioned silane anchoring agent, comprising the following steps:

[0022] (S1) mixing an epoxy-containing alkoxysilane monomer with an alcohol aqueous solution, and subjecting the mixture to a hydrolysis and polycondensation reaction under the action of a weak acid catalyst to obtain an epoxy-containing silane oligomer; wherein the molar ratio of the epoxy-containing alkoxysilane monomer to water in the alcohol aqueous solution is 1:(0.3-1.0);

[0023] (S2) co-condensing the epoxy-containing silane oligomer with the alkenyl-containing acyloxysilane, and then removing the low boiling point and filtering to obtain a silane anchoring agent.

[0024] Furthermore, in step (S1), the molar ratio of the epoxy-containing alkoxysilane monomer to water in the alcohol-water solution is 1:(0.3-0.7), preferably 1:(0.5-0.7). When the epoxy-containing alkoxysilane monomer is hydrolyzed, some of its alkoxy groups are hydrolyzed into silanol groups, which then condense to produce water. If the amount of water is too low, too little alkoxy groups will be hydrolyzed, making it difficult to condense into oligomers. If the amount of water is too high, too many silanol groups will be hydrolyzed from the alkoxy groups, resulting in excessive branching of the resulting oligomers, which will affect the anchoring effect of the final anchoring agent. Therefore, the ratio of the epoxy-containing alkoxysilane monomer to water must be controlled within the above range to partially hydrolyze the alkoxy groups.

[0025] Furthermore, the weak acid catalyst is used in an amount of 0.3-1.2 wt % of the epoxy-containing alkoxysilane monomer, preferably 0.4-0.8 wt %. Compared to alkaline catalysts and lithium catalysts, weak acid catalysts can reduce the ring opening of epoxy groups and can be directly used as a catalyst in step (S2) without further treatment.

[0026] Furthermore, in step (S1), the epoxy-containing alkoxysilane monomer is at least one of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltriethoxysilane, γ-(2,3-epoxypropoxy)propylmethyldimethoxysilane, γ-(2,3-epoxypropoxy)propylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltriethoxysilane; preferably γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-(2,3-epoxypropoxy)propylmethyldimethoxysilane or β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0027] Furthermore, in step (S1), the water content in the alcohol aqueous solution is 10-20 wt%, the alcohol is methanol or ethanol, and the water is deionized water. The purpose of adding alcohol is to promote better compatibility between the aqueous phase and the epoxy-containing alkoxysilane monomer.

[0028] Furthermore, in step (S1), the weak acid catalyst is at least one of an inorganic weak acid, an organic weak acid, a weak acid cation exchange resin, and a strong acid and weak base salt, such as formic acid, acetic acid, ferric chloride, ferrous chloride, cupric chloride, and ammonium chloride; preferably acetic acid or a weak acid cation exchange resin.

[0029] Furthermore, in step (S1), the conditions of the hydrolysis and polycondensation reaction are: temperature 40-65° C., time 2-6 h.

[0030] Furthermore, the structural formula of the epoxy-containing silane oligomer prepared in step (S1) is shown in Formula III below:

[0031]

[0032] Wherein, n, R1, R2, and R3 are the same as those in Formula I.

[0033] Furthermore, in step (S2), the molar ratio of the epoxy-containing silane oligomer (calculated as the epoxy-containing alkoxysilane monomer) to the alkenyl-containing acyloxysilane is 1:(0.3-1), preferably 1:(0.5-0.7). After co-condensation to form the silane anchoring agent, the alkenyl groups can participate in the addition reaction of the organosilicon system, firmly bonding to the coating; the epoxy groups interact with the substrate and form a tight bond. A certain balance between the two is required to achieve a good anchoring effect. Therefore, the ratio of the epoxy-containing silane oligomer to the alkenyl-containing acyloxysilane must be controlled within the above range.

[0034] Furthermore, in step (S2), the alkenyl-containing acyloxysilane is at least one of vinyl triacetoxysilane, vinyl methyl diacetoxysilane, allyl triacetoxysilane, and butyl triacetoxysilane; preferably vinyl triacetoxysilane and vinyl methyl diacetoxysilane.

[0035] Furthermore, in step (S2), the co-condensation conditions are: temperature 40-65° C., time 2-8 h.

[0036] The present invention also provides the use of the above-mentioned silane anchoring agent in the field of pressure-sensitive adhesives and release agents; preferably, the silane anchoring agent accounts for 1 to 3% of the total mass of the pressure-sensitive adhesive or release agent.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The anchoring agent of the present invention is a silane polymer with a relatively high content of epoxy groups in the side groups. It has a low-branched, non-overly cross-linked structure, which can play a good anchoring role. At the same time, the high content of epoxy groups can interact with the substrate and tightly connect to it, further promoting the improvement of the anchoring effect.

[0039] (2) In the present invention, a portion of the alkoxy groups is first hydrolyzed into silanol groups by hydrolysis and polycondensation of an epoxy-containing alkoxysilane monomer, thereby reducing the content of the alkoxy groups in the system. When used in a pressure-sensitive adhesive or a release agent, the bonding performance between the adhesive and the substrate can be improved.

[0040] (3) The anchoring agent of the present invention is a polymer formed by the condensation of an epoxy-containing silane oligomer and an alkenyl-containing acyloxysilane. Unlike physical blending, the epoxy and alkenyl groups are both in the molecular chain of the polymer. Therefore, the silane anchoring agent of the present invention has good compatibility with the pressure-sensitive adhesive system and the release agent system; at the same time, it does not have the irritating odor problem existing in small molecule anchoring agents.

[0041] (4) In step (S1) of the present invention, silane oligomers are prepared by hydrolyzing and polycondensing epoxy-containing alkoxysilane monomers under the action of a weakly acidic catalyst. Compared with alkaline catalysts and lithium catalysts, weakly acidic catalysts can not only reduce the ring-opening of epoxy groups, so that the epoxy content of the final anchoring agent is higher; but also can be directly applied to step (S2) without treatment and continue to be used as a catalyst; that is, the preparation process of the present invention has a high raw material utilization rate and a simple process. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is the H NMR spectrum of the silane anchoring agent prepared in Example 1.

[0043] Figure 2 This is the infrared spectrum of the silane anchoring agent prepared in Example 1. DETAILED DESCRIPTION

[0044] The present invention will be further described below with reference to specific examples, but the present invention is not limited to the following examples.

[0045] The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials are commercially available unless otherwise specified.

[0046] Example 1

[0047] A silane anchoring agent, the preparation method of which comprises the following steps:

[0048] (S1) 236 g (1 mol) of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 1.2 g of acetic acid were placed in a reaction kettle, nitrogen protection was turned on, the temperature was raised to 50° C., and 36 g of an ethanol solution with a water content of 15 wt% (5.4 g, i.e., 0.3 mol, of water) was added dropwise with stirring over a period of about 1 hour. After the addition was completed, the temperature was maintained for a hydrolysis and polycondensation reaction for 2 hours to obtain a mixed solution of epoxy-containing silane oligomers;

[0049] (S2) adding 162 g (0.7 mol) of vinyl triacetoxysilane to the above mixed solution, and carrying out a co-condensation reaction at 55° C. for 4 h; after the reaction, performing pressure distillation to remove low-boiling substances in the system, and filtering to obtain a silane anchoring agent.

[0050] The H NMR spectrum of silane anchoring agent is as follows Figure 1 As shown in the infrared spectrum Figure 2 shown.

[0051] The epoxy silane oligomer obtained in step (S1) was subjected to GPC test analysis, and the average polymerization degree n was calculated to be 2.6.

[0052] Example 2

[0053] The rest is the same as Example 1, except that in step (S1), the amount of ethanol solution used is 90 g (water is 9 g, i.e., 0.5 mol).

[0054] The epoxy silane oligomer prepared in step (S1) was subjected to GPC test analysis, and the average polymerization degree n was calculated to be 3.8.

[0055] Example 3

[0056] The rest is the same as Example 1, except that in step (S1), the amount of ethanol solution used is 84 g (water is 12.6 g, i.e., 0.7 mol).

[0057] The epoxy silane oligomer prepared in step (S1) was subjected to GPC test analysis, and the average polymerization degree n was calculated to be 4.6.

[0058] Example 4

[0059] The rest is the same as Example 1, except that in step (S1), the amount of ethanol solution used is 120 g (water is 18 g, i.e., 1 mol).

[0060] The epoxy silane oligomer prepared in step (S1) was subjected to GPC test analysis, and the average polymerization degree n was calculated to be 6.1.

[0061] Example 5

[0062] The rest is the same as Example 1, except that in step (S2), the amount of vinyltriacetoxysilane used is 6936 g (0.3 mol).

[0063] Example 6

[0064] The rest is the same as Example 1, except that in step (S2), the amount of vinyltriacetoxysilane used is 116 g (0.5 mol).

[0065] Example 7

[0066] The rest is the same as Example 1, except that in step (S2), the amount of vinyltriacetoxysilane used is 232 g (1 mol).

[0067] Example 8

[0068] The rest is the same as Example 1, except that: in step (S1), γ-(2,3-epoxypropyloxy)propyltrimethoxysilane is replaced by an equal molar amount of β-(3,4-epoxycyclohexyl)ethyltriethoxysilane; in step (S2), vinyldimethylacetoxysilane and vinyltriacetoxysilane are used, and the co-condensation time is 6 hours.

[0069] Comparative Example 1

[0070] The rest is the same as Example 1, except that in step (S1), the amount of ethanol solution used is 360 g (water is 54 g, i.e., 3 mol).

[0071] Comparative Example 2

[0072] The rest is the same as Example 1, except that in step (S1), the amount of ethanol solution used is 12 g (water is 1.8 g, i.e., 0.1 mol).

[0073] Comparative Example 3

[0074] The rest is the same as Example 1, except that in step (S1), an equal mass of magnesium oxide is used instead of acetic acid.

[0075] Results and Analysis

[0076] (1) Structural analysis

[0077] Figure 1 This is the H NMR spectrum of the silane anchoring agent prepared in Example 1. The chemical shifts in the figure show the hydrogens connected to each group. Figure 1 As marked.

[0078] Figure 2 This is the infrared spectrum of the silane anchoring agent prepared in Example 1, and the characteristic peaks of the main functional groups are marked as shown in the figure.

[0079] Based on the NMR spectrum and IR spectrum, the structural formula of the silane anchoring agent prepared in Example 1 can be obtained as follows:

[0080]

[0081] Ra represents a hydroxyl group or a methoxy group.

[0082] (2) Performance testing

[0083] The silane anchoring agents prepared in the embodiment and test example were respectively prepared according to the pressure-sensitive adhesive formulation in Table 1 below, coated on the corona-treated PET film using a 50-wire coating rod, baked at 150°C for 5 minutes, and then the samples were tested as follows:

[0084] Anchorage: The anchorage is judged by hand rubbing after 100-grid method to see if there is any debonding. The rating is 1-5, with 3 as qualified, below 3 as unqualified, 4 as good, and 5 as excellent. The anchorage is tested by boiling in water at 100°C for 2 hours and in a double 85 environment (temperature 85°C, humidity 85%) for 1 week.

[0085] Adhesion: The initial adhesion at high temperature (70°C, 20 min) and the aged adhesion at high temperature and high humidity (70°C, 80% humidity, 3 days) were measured using an AR2000 adhesion / peel tester from Cheminstruments, USA, in accordance with ASTM D3330.

[0086] The test results are shown in Table 2.

[0087] Table 1 Pressure sensitive adhesive formula

[0088] Components parts by mass Vinyl silicone rubber 100 MQ methyl silicone resin 92 Hydrogen silicone oil 5 Custer Catalyst 1 Silane anchoring agent 4 Toluene 80

[0089] Table 2 Silane anchoring agent performance test

[0090]

[0091] As can be seen from Table 2, the anchoring agent prepared by the present invention has a good effect in application and effectively improves the bonding performance of the pressure-sensitive adhesive. It has excellent anchoring properties both in boiling water at 100°C and in a dual high temperature and high humidity environment. When applied to a pressure-sensitive adhesive system, the adhesion fluctuation is small under high temperature and high humidity conditions.

[0092] The above contents are only preferred embodiments of the present invention and are not intended to limit the implementation scheme of the present invention. Ordinary technicians in this field can easily make corresponding changes or modifications based on the main concepts and spirit of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope of protection required by the claims.

Claims

1. A silane anchoring agent, characterized in that Prepared by a preparation method comprising the following steps: (S1) mixing an epoxy-containing alkoxysilane monomer with an alcohol aqueous solution, and subjecting the mixture to a hydrolysis and polycondensation reaction under the action of a weak acid catalyst to obtain an epoxy-containing silane oligomer; wherein the molar ratio of the epoxy-containing alkoxysilane monomer to water in the alcohol aqueous solution is 1:0.3-1.0; (S2) co-condensing the epoxy-containing silane oligomer with the alkenyl-containing acyloxysilane, and then removing the low boiling point and filtering to obtain a silane anchoring agent; In step (S1), the epoxy-containing alkoxysilane monomer is at least one of γ-(2,3-epoxypropyloxy)propyltrimethoxysilane, γ-(2,3-epoxypropyloxy)propyltriethoxysilane, γ-(2,3-epoxypropyloxy)propylmethyldimethoxysilane, γ-(2,3-epoxypropyloxy)propylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltriethoxysilane; In step (S2), the alkenyl-containing acyloxysilane is at least one of vinyl triacetoxysilane, vinyl methyl diacetoxysilane, allyl triacetoxysilane, and allyl triacetoxysilane.

2. The silane anchoring agent according to claim 1, characterized in that In step (S1), the molar ratio of the epoxy-containing alkoxysilane monomer to water in the alcohol aqueous solution is 1:0.3-0.7; and the amount of the weak acid catalyst used is 0.3-1.2 wt % of the epoxy-containing alkoxysilane monomer.

3. The silane anchoring agent according to claim 2, characterized in that The molar ratio of the epoxy-containing alkoxysilane monomer to water in the alcohol aqueous solution is 1:0.5-0.

7.

4. The silane anchoring agent according to claim 1, characterized in that In step (S1), the epoxy-containing alkoxysilane monomer is γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-(2,3-epoxypropoxy)propylmethyldimethoxysilane or β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

5. The silane anchoring agent according to claim 1, characterized in that In step (S1), the water content in the alcohol aqueous solution is 10-20 wt%, the alcohol is methanol or ethanol, and the water is deionized water; and / or The weak acid catalyst is at least one of an inorganic weak acid, an organic weak acid, a weak acid cation exchange resin, and a strong acid weak base salt; and / or The conditions of the hydrolysis and polycondensation reaction are: temperature 40-65° C., time 2-6 h.

6. The silane anchoring agent according to claim 1, characterized in that In step (S2), the molar ratio of the epoxy-containing silane oligomer to the alkenyl-containing acyloxysilane is 1:0.3-1, based on the epoxy-containing alkoxysilane monomer; the alkenyl-containing acyloxysilane is vinyl triacetoxysilane or vinyl methyl diacetoxysilane.

7. The silane anchoring agent according to claim 6, characterized in that In step (S2), the molar ratio of the epoxy-containing silane oligomer to the alkenyl-containing acyloxysilane is 1:0.5-0.7 based on the epoxy-containing alkoxysilane monomer.

8. The silane anchoring agent according to claim 1, characterized in that In step (S2), the co-condensation conditions are: temperature 40-65° C., time 2-8 h.

9. Use of the silane anchoring agent according to any one of claims 1 to 8 in the field of pressure-sensitive adhesives and release agents, characterized in that: The silane anchoring agent accounts for 1-3% of the total mass of the pressure-sensitive adhesive or release agent.

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