A biomass-based silane coupling agent and its preparation method and application

Abstract

The present invention provides a biomass-based silane coupling agent having a structure shown in Formula I, wherein R is independently selected from C4-C 20 Alkyl, C3-C 20 Cycloalkyl; R 1 Independently selected from propyl, ethylaminopropyl; R 2 Independently selected from methyl, ethyl; R 3 Independently selected from C1-C 10 Alkyl, C1-C 10 Alkoxy, hydroxyl; a is 0 or 1. By specifically designing the molecular structure of the silane coupling agent, the silane segment is selectively grafted as a side chain onto a tetraamide segment containing an unsaturated double bond. This silane coupling agent, when used as a tackifier for silicone sealants, can significantly improve the bonding performance between the prepared silicone sealant and the PBT substrate, particularly when immersed in water.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, in particular to a biomass-based silane coupling agent and a preparation method and application thereof. Background Art

[0002] Room temperature curing silicone rubber (RTV) offers excellent resistance to UV light, weathering, and high temperature and humidity. Compared to other sealants, its durability under harsh conditions is particularly outstanding. Single-component room temperature curing silicone sealants, in particular, exhibit excellent aging resistance due to the relatively stable silicon-oxygen bonds of their primary component. They are widely used in construction, automotive, lighting, and electrical and electronics applications. Polybutylene terephthalate (PBT) is widely used in electronic component packaging due to its excellent heat, moisture, oil, and corrosion resistance, electrical insulation, and machinability. In applications involving sealing and structural bonding, RTV is required to bond PBT plastic materials.

[0003] Generally, ordinary RTV silicone rubber uses conventional silane coupling agents as tackifiers, which have good adhesion to most metal and glass substrates. However, the bonding effect is not ideal for plastic substrates such as polybutylene terephthalate (PBT) materials, and the room temperature adhesion and water immersion adhesion are poor.

[0004] Therefore, it is necessary to develop specific tackifiers to improve the adhesion of RTV silicone rubber to PBT materials. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of existing RTV silicone rubber in terms of poor adhesion to plastic substrates and poor water immersion adhesion, and to provide a biomass-based silane coupling agent for use as a tackifier in RTV silicone rubber, which can significantly improve the adhesion between silicone rubber and substrates.

[0006] Another object of the present invention is to provide a method for preparing the biomass-based silane coupling agent.

[0007] Another object of the present invention is to provide use of the biomass-based silane coupling agent in the preparation of silicone rubber.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A biomass-based silane coupling agent having a structure as shown in Formula I:

[0010]

[0011] In Formula I, R is independently selected from C4-C 20 Alkyl, C3-C 20 Cycloalkyl; R 1Independently selected from propyl, ethylaminopropyl; R 2 Independently selected from methyl, ethyl; R 3 Independently selected from C1-C 10 Alkyl, C1-C 10 Alkoxy, hydroxy; a is 0 or 1.

[0012] The biomass-based silane coupling agent of the present invention: 1) contains polar hydroxyl, alkoxy, and amide groups, which can form hydrogen bonds with terminal carboxyl groups or hydroxyl groups in PBT materials. The unsaturated double bonds and aromatic groups in the biomass-based silane coupling agent can form a π-π conjugated effect with the phenyl groups in the PBT substrate, thereby having a strong bonding force with the PBT substrate. The alkoxy groups in the silane coupling agent can undergo a cross-linking reaction with the silicone rubber, thereby enhancing the interaction between the silicone rubber and the PBT substrate and improving the bonding performance at room temperature. 2) contains unsaturated double bonds (carbon-carbon double bonds) and tetraamide groups, which can jointly improve the interaction between the biomass-based silane coupling agent and the phenyl groups in the PBT substrate, thereby improving the bonding performance with the PBT at room temperature and in a water-immersion state. 3) The presence of methylene and aromatic groups effectively improves the compatibility of the silicone rubber system with PBT.

[0013] Preferably, said R is independently selected from C4-C 10 Alkyl, C3-C6 cycloalkyl.

[0014] Preferably, the biomass-based silane coupling agent is connected with R 3 The phenyl group of the group is one or two of 4-methoxyphenyl, 4-isopropylphenyl, (3,4-methyleneoxy)phenyl, 3-methoxy-4-hydroxyphenyl, and 2-hydroxyphenyl.

[0015] Preferably, the value of a is 0.

[0016] The preparation method of the biomass-based silane coupling agent comprises the following steps:

[0017] Itaconic acid, aminosilane, R 3 The substituted aromatic aldehyde and the solvent are mixed, stirred at 5-35° C. for 10-90 minutes, isocyanide is added, reacted at 5-60° C. for 0.5-4 hours, and the solvent is removed to prepare the biomass-based silane coupling agent.

[0018] In the present invention, the following reaction occurs between the above raw materials:

[0019]

[0020] Preferably, the aminosilane contains R 1 and R 2The group can be specifically selected from at least one of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminoethylaminopropyltrimethoxysilane, aminoethylaminopropyltriethoxysilane, aminopropylmethyldimethoxysilane, aminopropylmethyltriethoxysilane, aminoethylaminopropylmethyldimethoxysilane and aminoethylaminopropylmethyldiethoxysilane.

[0021] Preferably, the aromatic aldehyde includes at least one of salicylaldehyde, anisaldehyde, heliotropein, and vanillin. 3 The substituents may be substituted at any position of the aromatic aldehyde.

[0022] Preferably, the solvent is an alcohol solvent, and the alcohol solvent includes at least one of methanol, ethanol, propanol, and isopropanol.

[0023] Preferably, the itaconic acid, aminosilane, R 3 The molar ratio of the substituted aromatic aldehyde to the C-isonitrile is 1:(1-1.5):(1-1.5):1.

[0024] The present invention also protects the use of the above-mentioned biomass-based silane coupling agent in the preparation of an organosilicon sealant, wherein the organosilicon sealant comprises the following components in parts by weight:

[0025] 100 parts of polydimethylsiloxane, 2-10 parts of cross-linking agent, 5-100 parts of filler, 1-30 parts of plasticizer, 0.01-5 parts of catalyst, and 0.1-5 parts of the biomass-based silane coupling agent.

[0026] Cross-linking agents, fillers, plasticizers, and catalysts commonly used in silicone sealants can all be used in the present invention to prepare the silicone sealant.

[0027] Optionally, the polydimethylsiloxane includes but is not limited to at least one of α,ω-dihydroxy polydimethylsiloxane and methyldimethoxy-terminated polydimethylsiloxane. The viscosity of the polydimethylsiloxane at 25° C. is 1,000 to 100,000 mPa·s. The viscosity is measured using a rotational viscometer.

[0028] Optionally, the crosslinking agent includes but is not limited to ketoxime silane or alkoxysilane, and specifically can be selected from at least one of methyltributyketoxime silane, vinyltributyketoxime silane, and tetrabutylketoxime silane.

[0029] Optionally, the filler includes but is not limited to at least one of calcium carbonate, diatomaceous earth, quartz sand, and white carbon black.

[0030] Optionally, the plasticizer includes but is not limited to at least one of mineral oil and dimethyl silicone oil.

[0031] Alternatively, the catalyst may be an organotin catalyst or an organotitanium catalyst. The organotin catalyst includes, but is not limited to, at least one of dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, and dibutyltin acetylacetonate; the organotitanium catalyst includes, but is not limited to, at least one of tetrabutyl titanate, tetra-tert-butyl titanate, diisopropoxy titanium diacetylacetonate, and diisopropoxy titanium ethyl diacetylacetonate.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention specifically designs the molecular structure of a silane coupling agent, selectively grafting a siloxy segment as a side chain onto a tetraamide segment containing an unsaturated double bond. As a tackifier for an organic silicone sealant, the silane coupling agent can significantly improve the bonding performance between the prepared organic silicone sealant and a PBT substrate, particularly significantly improving the bonding performance when immersed in water. DETAILED DESCRIPTION

[0034] For better explanation of the purpose, technical scheme and advantage of the present invention, the present invention will be further described below in conjunction with specific embodiment, but embodiment does not limit the present invention in any form.Unless otherwise stated, the reagent, method and equipment adopted in the present invention are conventional reagents, methods and equipment in the art.Unless otherwise stated, the reagents and materials used in the present invention are commercially available.

[0035] Example 1

[0036] This embodiment provides a biomass-based silane coupling agent, and the preparation method is as follows:

[0037] Itaconic acid, aminopropyltrimethoxysilane and vanillin in a molar ratio of 1:1:1 were put into a reactor equipped with a stirrer and a thermometer, and methanol was added. Under nitrogen protection, the reaction was continued at a stirring speed of 200 rpm for 15 minutes. 1 mol of tert-butyl isocyanide was added at 25°C, and the stirring reaction was continued for 1 hour. The solvent methanol was distilled off to obtain the biomass-based silane coupling agent, which was sealed and stored for use. It was recorded as coupling agent A1, and its H NMR spectrum data were as follows: 0.56 (4H), 1.3 (18H), 1.60 (4H), 2.5 (4H), 2.85 (2H), 3.5-3.8 (24H), 5.5 (1H), 6.0 (1H), 6.4 (4H), 6.5 (2H).

[0038] The structural formula of coupling agent A1 is as follows:

[0039]

[0040] Example 2

[0041] This embodiment provides a biomass-based silane coupling agent, and the preparation method is as follows:

[0042] Itaconic acid, aminopropylmethyldiethoxysilane and salicylaldehyde in a molar ratio of 1:1:1 were put into a reactor equipped with a stirrer and a thermometer, and methanol was added. Under nitrogen protection, the reaction was continued at a stirring speed of 100 rpm for 0.5 h. 1 mol of tert-octyl isocyanide was added at 25° C. and the reaction was continued with stirring at 35° C. for 4 h. The solvent was distilled off to obtain the biomass-based silane coupling agent, which was sealed and stored for use. It was recorded as coupling agent A2. Its H NMR spectrum data are as follows: 0.15 (6H), 1.06 (18H), 1.20-1.40 (32H), 1.60 (4H), 2.85 (2H), 3.20 (4H), 3.80 (8H), 5.5 (1H), 5.8 (2H), 6.0 (1H), 6.6-6.7 (4H), 6.9 (4H).

[0043] The structural formula of coupling agent A2 is as follows:

[0044]

[0045] Example 3

[0046] This embodiment provides a biomass-based silane coupling agent, and the preparation method is as follows:

[0047] Itaconic acid, γ-aminoethylaminopropyltrimethoxysilane, and anisaldehyde in a molar ratio of 1:1:1 were placed in a reactor equipped with a stirrer and a thermometer, and methanol was added. Under nitrogen protection, the reaction was continued at a stirring speed of 200 rpm for 15 minutes. 1 mol of cyclopentyl isocyanide was added at 25° C., and the reaction was continued with stirring for 3 hours. The solvent was distilled off and the material was discharged to obtain the biomass-based silane coupling agent, which was sealed and stored for use. It was recorded as coupling agent A3, and its H NMR spectrum data were as follows: 0.55 (4H), 1.5 (12H), 1.70 (8H), 2.55-2.90 (14H), 3.5-3.6 (20H), 3.70 (6H), 5.5 (1H), 5.8 (2H), 6.0 (1H), 6.65 (4H), 6.95 (4H).

[0048] The structural formula of coupling agent A3 is as follows:

[0049]

[0050] Example 4

[0051] This embodiment provides a biomass-based silane coupling agent, and the preparation method is as follows:

[0052] Itaconic acid, γ-aminoethylaminopropylmethyldimethoxysilane, and heliotropin in a molar ratio of 1:1:1 were placed in a reactor equipped with a stirrer and a thermometer, and methanol was added. Under nitrogen protection, the reaction was continued at a stirring speed of 200 rpm for 15 minutes. 1 mol of cyclohexyl isocyanide was added at 25° C., and the reaction was continued with stirring for 1 hour. The solvent was distilled off and the material was discharged to obtain the biomass-based silane coupling agent, which was sealed and stored for use and was recorded as coupling agent A4. Its H NMR spectrum data are as follows: 0.15 (6H), 1.3 (4H), 1.4-1.7 (24H), 2.55-2.90 (14H), 3.5-3.6 (14H), 5.5 (1H), 5.80-5.9 (6H), 6.0 (1H), 6.45-6.55 (6H).

[0053] The structural formula of coupling agent A4 is as follows:

[0054]

[0055] Comparative Example 1

[0056] This comparative example provides a biomass-based silane coupling agent, which is prepared by the method of Reference Example 1. The difference from Example 1 is that itaconic acid is replaced by an equimolar amount of azelaic acid. The prepared coupling agent is denoted as B1, and its structural formula is shown below:

[0057]

[0058] Application Example 1

[0059] Provided is a silicone sealant, the preparation method of which is as follows:

[0060] 100 parts by weight of α,ω-dihydroxypolydimethylsiloxane (viscosity 80 Pa·s at 25°C), 5 parts by weight of dimethyl silicone oil (viscosity 350 mPa·s at 25°C), 40 parts by weight of stearic acid-treated calcium carbonate (particle size 60 nm, the weight of stearic acid used is 2.5% of the weight of untreated calcium carbonate), 4.5 parts by weight of methyltributylanoximesilane, 1.4 parts by weight of vinyltributylanoximesilane, 0.8 parts by weight of coupling agent A1, and 0.03 parts by weight of dibutyltin dilaurate were degassed and mixed in a universal mixer to prepare sealant 1.

[0061] Application Example 2

[0062] Provided is an organic silicone sealant, which is prepared by referring to the method of Application Example 1, except that coupling agent A1 is replaced by coupling agent A2 of equal mass.

[0063] Application Example 3

[0064] Provided is an organic silicone sealant, which is prepared by referring to the method of Application Example 1, except that coupling agent A1 is replaced by coupling agent A3 of equal mass.

[0065] Application Example 4

[0066] Provided is an organic silicone sealant, which is prepared by referring to the method of Application Example 1, except that coupling agent A1 is replaced by coupling agent A4 of equal mass.

[0067] Comparative Application Example 1

[0068] Provided is an organic silicone sealant, which is prepared by referring to the method of Application Example 1, except that the coupling agent A1 is replaced with an equal mass of γ-aminopropyltriethoxysilane (KH-550).

[0069] Comparative Application Example 2

[0070] Provided is an organic silicone sealant, which is prepared by referring to the method of Application Example 1, except that coupling agent A1 is replaced by coupling agent B1 of equal mass.

[0071] Performance Testing

[0072] The properties of the silicone sealants obtained in the above examples and comparative examples were characterized. The specific test items, test methods, and results are as follows:

[0073] The silicone sealants prepared in the above application examples and comparative application examples were used to prepare H-type adhesion test pieces (using Al-PBT substrate) according to the method provided in Chapter 7 of GB / T13477.8-2002, and vulcanized and cured for 7 days in an environment with a temperature of (23±2)°C and a relative humidity of (50±5)%.

[0074] The adhesion performance of the silicone sealant to the substrate was then tested at room temperature (23°C), after being immersed in water for 28 days, and after being irradiated with UV light for 168 hours. The test results are shown in Table 1:

[0075] Table 1

[0076]

[0077]

[0078] From the above results we can see that:

[0079] By comparing the bonding properties of sealants at room temperature, immersed in water for 28 days, and irradiated with ultraviolet light for 168 hours, it was found that the silicone sealant to which the biomass-based silane coupling agent prepared according to the embodiments of the present invention was added had a bonding failure area of ​​less than 10%, a bonding strength greater than 0.80 MPa, and a bonding strength retention rate greater than 80%.

[0080] In Comparative Example 1, the coupling agent of the present invention was not added, but an ordinary silane coupling agent was added; in the coupling agent of Comparative Example 2, the main chain did not contain both unsaturated double bonds and amide groups, and the bonding properties of the prepared silicone sealant, especially the water immersion bonding properties, were significantly deteriorated.

[0081] 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 the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A biomass-based silane coupling agent, characterized in that: Having the structure shown in Formula I: Formula I In Formula I, R is independently selected from C4-C 20 Alkyl, C3-C 20 Cycloalkyl; R 1 Independently selected from propylene, ethyleneaminopropyl; R 2 Independently selected from methyl, ethyl; R 3 Independently selected from C1-C 10 Alkyl, C1-C 10 Alkoxy, hydroxy; a is 0 or 1.

2. The biomass-based silane coupling agent according to claim 1, characterized in that The R is independently selected from C4-C 10 Alkyl, C3-C6 cycloalkyl.

3. The biomass-based silane coupling agent according to claim 1, characterized in that Connected with R 3 The phenyl group of the group is one or two of 4-methoxyphenyl, 4-isopropylphenyl, 3,4-methylenedioxyphenyl, 3-methoxy-4-hydroxyphenyl, and 2-hydroxyphenyl.

4. The biomass-based silane coupling agent according to claim 1, characterized in that The value of a is 0.

5. The method for preparing a biomass-based silane coupling agent according to any one of claims 1 to 4, characterized in that: The steps include: Itaconic acid, aminosilane, R 3 The substituted aromatic aldehyde and the solvent are mixed, stirred at 5-35° C. for 10-90 minutes, isocyanide is added, reacted at 5-60° C. for 0.5-4 hours, and the solvent is removed to prepare the biomass-based silane coupling agent.

6. The method for preparing a biomass-based silane coupling agent according to claim 5, wherein: The aminosilane includes at least one of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminoethylaminopropyltrimethoxysilane, aminoethylaminopropyltriethoxysilane, aminopropylmethyldimethoxysilane, aminopropylmethyltriethoxysilane, aminoethylaminopropylmethyldimethoxysilane, and aminoethylaminopropylmethyldiethoxysilane.

7. The method for preparing a biomass-based silane coupling agent according to claim 5, wherein: The aromatic aldehyde includes at least one of salicylaldehyde, anisaldehyde, heliotropein, and vanillin.

8. The method for preparing a biomass-based silane coupling agent according to claim 5, wherein: The solvent is an alcohol solvent, and the alcohol solvent includes at least one of methanol, ethanol, propanol, and isopropanol.

9. The method for preparing a biomass-based silane coupling agent according to claim 5, wherein: The itaconic acid, aminosilane, R 3 The molar ratio of the substituted aromatic aldehyde and the isonitrile is 1:(1-1.5):(1-1.5):

1.

10. Use of the biomass-based silane coupling agent according to any one of claims 1 to 4 in the preparation of an organosilicon sealant, characterized in that: The organosilicon sealant comprises the following components in parts by weight: 100 parts of polydimethylsiloxane, 2-10 parts of a cross-linking agent, 5-100 parts of a filler, 1-30 parts of a plasticizer, 0.01-5 parts of a catalyst, and 0.1-5 parts of the biomass-based silane coupling agent according to any one of claims 1 to 4.

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