Silane-modified single-component moisture-curing polyurethane adhesive and preparation method thereof

Abstract

The invention discloses a silane modified single-component moisture-curing polyurethane adhesive and a preparation method thereof, and belongs to the technical field of polyurethane adhesives, the polyurethane adhesive comprises the following raw materials by mass: 70-90 parts of polyether polyol, 1-3 parts of a silane coupling agent, 1-3 parts of a silane coupling agent, 1-3 parts of a silane coupling agent, 1-3 parts of a silane coupling agent, and 1-3 parts of a silane coupling agent. 12 to 18 parts of S (at) nano-S O < 2 >; 25 to 45 parts of diisocyanate; and 0.1 to 1 part of a chain extender. The silane modified single-component moisture-curing polyurethane adhesive prepared from the self-made synthesized nano-Si O2 composite silane coupling agent S (at) nano-Si O2 has the advantages that almost no bubble is generated in the curing process, the appearance is obviously improved, and the tensile strength and the tensile shear strength are obviously improved compared with those of a common single-component moisture-curing polyurethane adhesive; besides, toxic substances such as a curing agent and heavy metal salt do not need to be added in the formula as the curing agent, toxic and side effects harmful to human bodies are avoided, and physical and psychological health of sizing personnel is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane adhesives, and particularly relates to a silane-modified single-component moisture-curing polyurethane adhesive and a preparation method thereof. Background Art

[0002] Polyurethane (PU) adhesive refers to a type of adhesive containing urethane groups (—NHCOO—) or isocyanate groups (—NCO) in the molecular chain. When the polyurethane adhesive is cured, the -NCO group in the system reacts with substances containing active hydrogen to form crosslinks and solidify. It has excellent adhesion, low temperature resistance, wear resistance and fatigue resistance, and is widely used in automobile manufacturing, wood processing, aerospace and other fields. PU adhesives can be divided into two types: single-component and two-component. Compared with two-component PU adhesives, single-component PU adhesives can be cross-linked with water molecules in the air to solidify. The steps of metering and adding curing agent are omitted during use, and the construction is simple and convenient.

[0003] However, the one-component PU adhesive has a high isocyanate content, which easily reacts with water vapor in the air to form substituted urea, resulting in gelation. In addition, unstable amino acid (—NH—COOH) is formed during the curing process, and decarboxylation reaction quickly occurs to generate CO2, thereby generating bubbles. The adhesive has defects such as low bonding strength, poor high temperature resistance, poor weather resistance, and water sensitivity, which affect the appearance and performance of the product. Summary of the invention

[0004] One of the purposes of the present invention is to provide a silane-modified one-component moisture-curing polyurethane adhesive to solve the problem in the background art that -NCO groups are prone to generate CO2 gas, resulting in poor performance of the one-component PU adhesive;

[0005] A second object of the present invention is to provide a method for preparing a silane-modified one-component moisture-curing polyurethane adhesive.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] In a first aspect, a silane-modified one-component moisture-curing polyurethane adhesive comprises the following components in parts by weight:

[0008] Polyether polyol: 70-90 parts;

[0009] S@nano-SiO2: 12-18 parts;

[0010] Diisocyanate: 25-45 parts;

[0011] Chain extender: 0.1-1 part.

[0012] The S@nano-SiO2 is prepared by the following steps:

[0013] S1. After TEOS (tetraethyl orthosilicate), anhydrous ethanol and CTAB aqueous solution (hexadecyltrimethylammonium bromide) are mixed evenly, 3-mercaptopropyltriethoxysilane (KH590) is added and mixed evenly, hydrochloric acid is slowly added dropwise, and stirred at 60-80°C for reflux reaction for 4-6h, and naturally cooled to room temperature (25-30°C) to obtain mercaptosilane-modified nano-SiO2;

[0014] S2. Add mercaptosilane-modified nano-SiO2 and vinyltriethoxysilane (A-151) into THF (tetrahydrofuran) and stir to disperse, then add 2,2-dimethoxy-2-phenylacetophenone (DMPA), place under 150W ultraviolet lamp to react for 3-6h, remove the solvent by rotary evaporation, collect the nano-SiO2 composite silane coupling agent, and name it S@nano-SiO2.

[0015] Furthermore, the usage ratio of TEOS, anhydrous ethanol, CTAB, KH590 and hydrochloric acid is 1 g: 2-4 g: 100 mL: 0.1-0.2 g: 0.7-0.9 g.

[0016] Furthermore, the mass concentration of the CTAB aqueous solution is 0.2-0.5%, and the concentration of hydrochloric acid is 10%.

[0017] Furthermore, the usage ratio of the mercaptosilane-modified nano-SiO2, vinyltriethoxysilane and 2,2-dimethoxy-2-phenylacetophenone is 1g:5-8g:0.01g.

[0018] Furthermore, the molecular weight of the polyether polyol is 1000-2000, including polyether polyol 210 or polyether polyol 220.

[0019] Furthermore, the chain extender includes polyethylene glycol 300, 1,4-butanediol or ethylenediamine.

[0020] Furthermore, the diisocyanate includes diphenylmethane diisocyanate, toluene diisocyanate or hexamethylene diisocyanate.

[0021] Furthermore, the stirring speed is 100-300 rpm.

[0022] In a second aspect, a method for preparing a silane-modified one-component moisture-curing polyurethane adhesive comprises the following steps:

[0023] The polyether polyol was dehydrated under reduced pressure at 110-130°C and -0.09MPa for 1-3h, then cooled to 60-80°C, and diisocyanate and chain extender were added under nitrogen to react until the -NCO group content remained unchanged. S@nano-S i O2 was slowly added dropwise for end-capping, and the reaction was continued to the end point to obtain a silane-modified one-component moisture-curing polyurethane adhesive.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention provides a silane-modified one-component moisture-curing polyurethane adhesive and a preparation method thereof. The silane-modified one-component moisture-curing polyurethane adhesive prepared by using a homemade synthesized nano-SiO2 composite silane coupling agent S@nano-SiO2 generates almost no bubbles during the curing process, and the appearance is significantly improved. The tensile strength and tensile shear strength are significantly improved compared with ordinary one-component moisture-curing polyurethane adhesives. In addition, there is no need to add toxic substances such as curing agents and heavy metal salts as curing agents in the formula, and no harmful side effects will be produced on the human body, thereby ensuring the physical and mental health of the glue applicators.

[0026] 2. The self-synthesized nano-SiO2 composite silane coupling agent S@nano-SiO2 of the present invention first undergoes hydrolysis and condensation to form Si iOSi bonds during the polyurethane prepolymerization and curing process, thereby avoiding the generation of CO2 from the source; on the other hand, the KH590 hydrophobic group is modified in the Si atom, which hinders the condensation between the surrounding Si-OH and replaces a part of the -OH, further preventing the absorption of water vapor, and significantly enhancing the stability and water vapor resistance. In addition, during the curing process, by introducing the hydrophobic group of nano-SiO2, the ability to resist uneven capillary tension is enhanced due to the presence of steric hindrance, and the solid energy film-forming effect is better.

[0027] 3. The present invention uses CTAB as a template and KH590 silane coupling agent to modify SiO2. The prepared nano-SiO2 has good hydrophobicity and thermal stability. Adding a small amount of surfactant CTAB can reduce the surface tension and further improve the dispersibility of SiO2, so that the molecules form an orderly assembly. The vinyl group in vinyl triethoxysilane and the mercapto group in the nano-SiO2 modified with mercaptosilane undergo a mercapto-ene click chemical reaction, so that the silanes are grafted and bridged, and a plurality of linear molecules or micro-branched molecules are further formed with the nano-SiO2. The organic-inorganic three-dimensional network structure crosses. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] S@nano-SiO2 was prepared by the following steps:

[0030] S1. After TEOS, anhydrous ethanol and 0.2-0.5% CTAB aqueous solution are mixed evenly, KH590 is added and mixed evenly, 10% hydrochloric acid is slowly added dropwise, and the mixture is stirred and refluxed at 60-80°C and 100-300rpm for 4-6h, and naturally cooled to room temperature to obtain mercaptosilane-modified nano-SiO2; the dosage ratio of TEOS, anhydrous ethanol, CTAB, KH590 and hydrochloric acid is 1g: 2-4g: 100mL: 0.1-0.2g: 0.7-0.9g;

[0031] S2. Add mercaptosilane-modified nano-SiO2 and A-151 into THF and stir to disperse, then add DMPA and react under a 150W ultraviolet lamp for 3-6 hours. Remove the solvent by rotary evaporation and collect the nano-SiO2 composite silane coupling agent, named S@nano-SiO2. The dosage ratio of mercaptosilane-modified nano-SiO2, vinyltriethoxysilane and 2,2-dimethoxy-2-phenylacetophenone is 1g:5-8g:0.01g.

[0032] A method for preparing a silane-modified one-component moisture-curing polyurethane adhesive comprises the following steps:

[0033] 70-90 parts of polyether polyol with a molecular weight of 1000-2000 are dehydrated under reduced pressure at 110-130°C and -0.09MPa for 1-3h, then cooled to 60-80°C, 25-45 parts of diisocyanate and 0.1-1 part of chain extender are added under nitrogen, and the reaction is carried out until the -NCO group content remains unchanged. 12-18 parts of S@nano-S i O2 are slowly added dropwise for end-capping, and the reaction is carried out to the end point to obtain a silane-modified one-component moisture-curing polyurethane adhesive.

[0034] In a specific implementation case, the polyether polyol may be polyether polyol 210 or polyether polyol 220.

[0035] In a specific implementation case, the diisocyanate may be diphenylmethane diisocyanate, toluene diisocyanate or hexamethylene diisocyanate.

[0036] In a specific embodiment, the chain extender can be selected from polyethylene glycol 300, 1,4-butanediol or ethylenediamine.

[0037] Example 1

[0038] S@nano-SiO2 was prepared by the following steps:

[0039] S1. After 1g TEOS, 3g anhydrous ethanol and 100mL of 0.4% CTAB aqueous solution were mixed evenly, 0.15g KH590 was added and mixed evenly, 0.8g 10% hydrochloric acid was slowly added dropwise, and the mixture was stirred and refluxed at 70°C and 200rpm for 5h, and then naturally cooled to room temperature to obtain mercaptosilane-modified nano-SiO2;

[0040] S2. Add 1g of mercaptosilane-modified nano-S i O2 and 6.5g of A-151 into THF and stir to disperse, then add 0.01g of DMPA, place under a 150W ultraviolet lamp to react for 5h, remove the solvent by rotary evaporation, and collect S@nano-S i O2.

[0041] Example 2

[0042] S@nano-SiO2 was prepared by the following steps:

[0043] S1. After 1g TEOS, 3g anhydrous ethanol and 100mL 0.4% CTAB aqueous solution were mixed evenly, 0.1g KH590 was added and mixed evenly, 0.8g 10% hydrochloric acid was slowly added dropwise, and the mixture was stirred and refluxed at 70°C and 200rpm for 5h, and then naturally cooled to room temperature to obtain mercaptosilane-modified nano-SiO2;

[0044] S2. Add 1g of mercaptosilane-modified nano-S i O2 and 5g of A-151 into THF and stir to disperse, then add 0.01g of DMPA, place under a 150W ultraviolet lamp to react for 5h, remove the solvent by rotary evaporation, and collect S@nano-S i O2.

[0045] Example 3

[0046] S@nano-SiO2 was prepared by the following steps:

[0047] S1. After 1g TEOS, 3g anhydrous ethanol and 100mL 0.4% CTAB aqueous solution were mixed evenly, 0.2g KH590 was added and mixed evenly, 0.8g 10% hydrochloric acid was slowly added dropwise, and the mixture was stirred and refluxed at 70°C and 200rpm for 5h, and then naturally cooled to room temperature to obtain mercaptosilane-modified nano-SiO2;

[0048] S2. Add 1g of mercaptosilane-modified nano-S i O2 and 8g of A-151 into THF and stir to disperse, then add 0.01g of DMPA, place under a 150W ultraviolet lamp to react for 5h, remove the solvent by rotary evaporation, and collect S@nano-S i O2.

[0049] Example 4

[0050] A method for preparing a silane-modified one-component moisture-curing polyurethane adhesive comprises the following steps:

[0051] 80 parts of polyether polyol 220 were dehydrated under reduced pressure at 120°C and -0.09 MPa for 2 h, then cooled to 70°C, 35 parts of toluene diisocyanate and 0.5 parts of 1,4-butanediol were added under nitrogen, and the reaction was continued until the -NCO group content remained unchanged. 15 parts of S@nano-SiO2 prepared in Example 1 were slowly added dropwise for end-capping, and the reaction was continued to the end point to obtain a silane-modified one-component moisture-curing polyurethane adhesive.

[0052] Example 5

[0053] A method for preparing a silane-modified one-component moisture-curing polyurethane adhesive comprises the following steps:

[0054] 80 parts of polyether polyol 220 were dehydrated under reduced pressure at 120°C and -0.09 MPa for 2 h, then cooled to 70°C, 35 parts of toluene diisocyanate and 0.5 parts of 1,4-butanediol were added under nitrogen, and the reaction was continued until the -NCO group content remained unchanged. 15 parts of S@nano-SiO2 prepared in Example 2 were slowly added dropwise for end-capping, and the reaction was continued to the end point to obtain a silane-modified one-component moisture-curing polyurethane adhesive.

[0055] Example 6

[0056] A method for preparing a silane-modified one-component moisture-curing polyurethane adhesive comprises the following steps:

[0057] 80 parts of polyether polyol 220 were dehydrated under reduced pressure at 120°C and -0.09 MPa for 2 h, then cooled to 70°C, 35 parts of toluene diisocyanate and 0.5 parts of 1,4-butanediol were added under nitrogen, and the reaction was continued until the -NCO group content remained unchanged. 15 parts of S@nano-SiO2 prepared in Example 3 were slowly added dropwise for end-capping, and the reaction was continued to the end point to obtain a silane-modified one-component moisture-curing polyurethane adhesive.

[0058] Comparative Example 1

[0059] The silane-modified one-component moisture-curing polyurethane adhesive is prepared by end-capping the mercaptosilane-modified nano-SiO2 prepared by S1 in Example 1, comprising the following steps:

[0060] 80 parts of polyether polyol 220 were dehydrated under reduced pressure at 120°C and -0.09 MPa for 2 h, then cooled to 70°C, and 35 parts of toluene diisocyanate and 0.5 parts of 1,4-butanediol were added under nitrogen to react until the -NCO group content remained unchanged. 15 parts of mercaptosilane-modified nano-SiO2 were slowly added dropwise for end-capping, and the reaction was continued to the end point to obtain a silane-modified one-component moisture-curing polyurethane adhesive.

[0061] Comparative Example 2

[0062] S@nano / SiO2, the preparation steps are different from those in Example 1, except that the CTAB aqueous solution with a mass concentration of 0.4% in S1 is replaced with an equal volume of deionized water, and the remaining steps and parameters are the same as those in Example 1;

[0063] The composite silane coupling agent is used for end-capping to prepare a silane-modified one-component moisture-curing polyurethane adhesive, comprising the following steps:

[0064] 80 parts of polyether polyol 220 were dehydrated under reduced pressure at 120°C and -0.09 MPa for 2 h, then cooled to 70°C, and 35 parts of toluene diisocyanate and 0.5 parts of 1,4-butanediol were added under nitrogen and reacted until the -NCO group content remained unchanged. 15 parts of S@nano / SiO2 were slowly added dropwise for end-capping, and the reaction was continued to the end point to obtain a silane-modified one-component moisture-curing polyurethane adhesive.

[0065] Comparative Example 3

[0066] A-151 / KH590 was prepared by the following steps:

[0067] 0.15 g KH590 and 6.5 g A-151 were added to THF and stirred to disperse, and then 0.01 g DMPA was added, and the mixture was reacted under a 150 W UV lamp for 5 h, and the solvent was removed by rotary evaporation, and A-151 / KH590 was collected;

[0068] The composite silane coupling agent is used for end-capping to prepare a silane-modified one-component moisture-curing polyurethane adhesive, comprising the following steps:

[0069] 80 parts of polyether polyol 220 were dehydrated under reduced pressure at 120°C and -0.09 MPa for 2 hours, then cooled to 70°C, 35 parts of toluene diisocyanate and 0.5 parts of 1,4-butanediol were added under nitrogen, and the reaction was continued until the -NCO group content remained unchanged. 15 parts of A-151 / KH590 were slowly added dropwise for end-capping, and the reaction was continued to the end point to obtain a silane-modified one-component moisture-curing polyurethane adhesive.

[0070] Comparative Example 4

[0071] A method for preparing a silane-modified one-component moisture-curing polyurethane adhesive comprises the following steps:

[0072] 80 parts of polyether polyol 220 were dehydrated under reduced pressure at 120°C and -0.09 MPa for 2 hours, then cooled to 70°C, 35 parts of toluene diisocyanate and 0.5 parts of 1,4-butanediol were added under nitrogen, and the reaction was continued until the -NCO group content remained unchanged. 15 parts of KH590 were slowly added dropwise for end-capping, and the reaction was continued to the end point to obtain a silane-modified one-component moisture-curing polyurethane adhesive.

[0073] Comparative Example 5

[0074] A method for preparing a silane-modified one-component moisture-curing polyurethane adhesive comprises the following steps:

[0075] 80 parts of polyether polyol 220 were dehydrated under reduced pressure at 120°C and -0.09 MPa for 2 hours, then cooled to 70°C, 35 parts of toluene diisocyanate and 0.5 parts of 1,4-butanediol were added under nitrogen, and the reaction was continued until the -NCO group content remained unchanged. 15 parts of A-151 were slowly added dropwise for end-capping, and the reaction was continued to the end point to obtain a silane-modified one-component moisture-curing polyurethane adhesive.

[0076] Comparative Example 6

[0077] A method for preparing a one-component moisture-curing polyurethane adhesive comprises the following steps:

[0078] 80 parts of polyether polyol 220 were dehydrated under reduced pressure at 120° C. and −0.09 MPa for 2 h, then cooled to 70° C., and 35 parts of toluene diisocyanate and 0.5 parts of 1,4-butanediol were added under nitrogen and reacted to the end point to obtain a one-component moisture-curing polyurethane adhesive.

[0079] The performance tests were performed on the one-component moisture-curing polyurethane adhesives prepared in Examples 4-6 and Comparative Examples 1-6:

[0080] The prepared one-component moisture-curing polyurethane adhesive was poured into a polytetrafluoroethylene mold, aged in a forced air oven at 100°C for 10 hours, and then cured at room temperature for one week to be tested:

[0081] Tensile strength and elongation at break: measured in accordance with GB / T 528-2009 standard.

[0082] Average number of surface bubbles: measured by scanning electron microscopy of gold-sprayed samples.

[0083] Water contact angle: The contact angle of deionized water (about 5L) on the surface of the cured sample was measured using a static contact angle meter. The sample was cut into approximately 3.0 cm x 2.0 cm sizes. Three different locations on the same sample were measured and the average value was taken as the final contact angle measurement value.

[0084] Water contact angle: The contact angle of deionized water (about 5L) on the surface of the cured sample was measured using a static contact angle meter. The sample was cut into approximately 3.0 cm x 2.0 cm sizes. Three different locations on the same sample were measured and the average value was taken as the final contact angle measurement value.

[0085] Viscosity: Viscosity test is carried out according to GB-T2794-2013 "Determination of viscosity of adhesives - Single cylinder rotational viscometer method".

[0086] The test results are shown in Table 1:

[0087] Table 1

[0088]

[0089]

[0090] It can be seen from Table 1 that the silane-modified one-component moisture-curing polyurethane adhesive prepared by the present invention and the silane-modified one-component moisture-curing polyurethane adhesive prepared by using the homemade synthesized nano-SiO2 composite silane coupling agent S@nano-SiO2 have almost no bubble generation during the curing process, and the appearance is significantly improved, and the tensile strength and tensile shear strength are significantly improved compared with the ordinary one-component moisture-curing polyurethane adhesive; in addition, there is no need to add toxic substances such as curing agents and heavy metal salts as curing agents in the formula, and no harmful toxic side effects will be produced to the human body, thereby ensuring the physical and mental health of the glue applicators.

[0091] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0092] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A silane-modified one-component moisture-curing polyurethane adhesive, It is characterized in that The following raw materials are included by mass: Polyether polyol: 70-90 parts; S@nano-SiO 2 : 12-18 parts; diisocyanate: 25-45 parts; chain extender: 0.1-1 parts.

2. A silane-modified one-component moisture-curing polyurethane adhesive according to claim 1, It is characterized in that The S@nano-SiO 2 , prepared by the following steps: S1. After TEOS, anhydrous ethanol and CTAB aqueous solution are mixed evenly, 3-mercaptopropyltriethoxysilane is added and mixed evenly, hydrochloric acid is slowly added dropwise, and the mixture is stirred and refluxed at 60-80°C for 4-6h, and then cooled naturally to room temperature to obtain mercaptosilane-modified nano-SiO 2 ; S2. The mercaptosilane-modified nano-SiO 2 and vinyl triethoxysilane were added to THF and stirred to disperse, and then 2,2-dimethoxy-2-phenylacetophenone was added, and the mixture was placed under a 150W UV lamp for 3-6 hours. The solvent was removed by rotary evaporation, and S@nano-SiO 2 .

3. A silane-modified one-component moisture-curing polyurethane adhesive according to claim 2, It is characterized in that The usage ratio of the TEOS, anhydrous ethanol, CTAB, KH590 and hydrochloric acid is 1g: 2-4g: 100mL: 0.1-0.2g: 0.7-0.9g.

4. A silane-modified one-component moisture-curing polyurethane adhesive according to claim 2, It is characterized in that The mass concentration of the CTAB aqueous solution is 0.2-0.5%, and the concentration of hydrochloric acid is 10%.

5. A silane-modified one-component moisture-curing polyurethane adhesive according to claim 2, It is characterized in that The mercaptosilane-modified nano-SiO 2 The usage ratio of vinyltriethoxysilane and 2,2-dimethoxy-2-phenylacetophenone is 1g:5-8g:0.01g.

6. A silane-modified one-component moisture-curing polyurethane adhesive according to claim 1, It is characterized in that The molecular weight of the polyether polyol is 1000-2000.

7. A silane-modified one-component moisture-curing polyurethane adhesive according to claim 1, It is characterized in that The chain extender includes polyethylene glycol 300, 1,4-butanediol or ethylenediamine.

8. A silane-modified one-component moisture-curing polyurethane adhesive according to claim 1, It is characterized in that The diisocyanate includes diphenylmethane diisocyanate, toluene diisocyanate or hexamethylene diisocyanate.

9. A method for preparing the silane-modified one-component moisture-curing polyurethane adhesive as claimed in claim 1, It is characterized in that The following steps are involved: After dehydrating the polyether polyol under reduced pressure at 110-130°C and -0.09 MPa for 1-3 h, cool to 60-80°C, add diisocyanate and chain extender under nitrogen, react until the -NCO group content remains unchanged, and slowly add S@nano-Si O 2 The end-capping is performed and the reaction is carried out to an end point to obtain a silane-modified one-component moisture-curing polyurethane adhesive.

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