UV-moisture dual-curing polyurethane sealant and preparation method thereof

Abstract

The invention discloses a UV-moisture dual-curing polyurethane sealant and a preparation method thereof. The sealant comprises the following components in parts by weight: 100 parts of a polyurethane prepolymer, 50-100 parts of a filler, 5-10 parts of titanium dioxide, 2-5 parts of a thixotropic agent, 1-5 parts of an oxazolidine dewatering agent, 1-5 parts of an adhesion promoter, 1-3 parts of a catalyst and 1-3 parts of a photoinitiator. The UV-moisture dual-curing polyurethane sealant disclosed by the invention can be cured through UV radiation or moisture, combines the advantages of UV radiation curing and moisture curing, solves the problems of complex operation and short working life of a double-component polyurethane sealant, overcomes the defects of low curing speed and easy blistering of a traditional single-component moisture-curing polyurethane sealant, and has the advantages of simple preparation process and low cost. Meanwhile, the defect that a traditional UV glue light blocking area cannot be cured is overcome, rapid curing is achieved, and meanwhile the application range is effectively widened.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane sealants, and in particular relates to a UV-moisture dual-curing polyurethane sealant and a preparation method thereof. Background Art

[0002] Sealant is one of the important process materials in the production of automobiles and other industries. Polyurethane sealant has become the fastest-growing high-end sealing material in the automobile manufacturing industry because of its wide adjustable performance range, strong adaptability, wear resistance, oil resistance, good low-temperature elasticity, long service life, and high bonding strength. However, the traditional one-component wet curing system has problems such as slow curing speed, poor high temperature resistance, easy bubbling during the cross-linking process, resulting in poor bonding effect, and the two-component curing system has problems such as complex operation and short service life. Summary of the invention

[0003] In view of the above shortcomings of the prior art, the purpose of the present invention is to provide a UV-moisture dual-curing polyurethane sealant and a preparation method thereof, which can not only avoid the unsatisfactory bonding effect of a single-component polyurethane sealant and the inconvenience of using a two-component polyurethane sealant, but also further improve the comprehensive performance of the sealant.

[0004] To achieve the above objectives, the technical solutions adopted are:

[0005] One of the purposes of the present invention is to provide a UV-moisture dual-curing polyurethane sealant, comprising the following components in parts by weight:

[0006] 100 parts of polyurethane prepolymer, 50-100 parts of filler, 5-10 parts of titanium dioxide, 2-5 parts of thixotropic agent, 1-5 parts of oxazolidine dewatering agent, 1-5 parts of adhesion promoter, 1-3 parts of catalyst, 1-3 parts of photoinitiator;

[0007] The polyurethane prepolymer is prepared from 15-40 parts of polyether polyol, 5-10 parts of 3-(trimethylsilyl)-1,2-propylene glycol, 5-15 parts of acrylate diol, 10-20 parts of isocyanate, 10-30 parts of reactive diluent and 0.1-0.3 parts of inhibitor.

[0008] Further, the acrylate diol has the following molecular structure:

[0009]

[0010] The beneficial effect of adopting the above further technical solution is that the acrylic ester diol has two hydroxyl groups, and the double bonds can be grafted into the polyurethane segment through a simple polymerization reaction, so that there is no free acrylic ester and it has a lower VOC; at the same time, the molecule contains a six-membered ring and a long chain segment, which balances strength and flexibility.

[0011] Furthermore, the reactive diluent has the following molecular structure:

[0012]

[0013] The reactive diluent is Uitra LITE2020 produced by Cardolite Chemical.

[0014] The beneficial effect of adopting the above-mentioned further technical scheme is that the reactive diluent contains hydroxyl groups and double bonds, which can be grafted into the system through polymerization reaction without free diluent, thereby greatly improving the bonding strength of the system; at the same time, the double bonds it carries increase the double bond concentration of the system, greatly increasing the reaction activity of the double bonds, and can effectively reduce oxygen inhibition.

[0015] Furthermore, the filler is one or a combination of light calcium carbonate, heavy calcium carbonate, and talcum powder; the thixotropic agent is one or two of fumed silica and organic bentonite; and the catalyst is one or a combination of two of dibutyltin dilaurate, stannous octoate, bismorpholine diethyl ether, and triethylenediamine.

[0016] Furthermore, the adhesion promoter is Shin-Etsu's long-chain silane coupling agent KBM-1083; the photoinitiator is one or a combination of 184 photoinitiator and 1173 photoinitiator.

[0017] Furthermore, the polymerization inhibitor is a combination of one or more of hydroquinone, p-tert-butylcatechol and cresol.

[0018] Furthermore, the polyether polyol is a difunctional polyoxypropylene ether with a number average molecular weight of 2000-4000; the isocyanate is one or a combination of two of diphenylmethane diisocyanate, toluene diisocyanate and isophorone diisocyanate.

[0019] Furthermore, the oxazolidine dehydrating agent is ALT201 produced by Changde Elite New Material Technology Co., Ltd.

[0020] A second object of the present invention is to provide a method for preparing the above-mentioned UV-moisture dual-curing polyurethane sealant, comprising the following steps:

[0021] 1) Dehydrate the polyether polyol and 3-(trimethylsilyl)-1,2-propylene glycol at 110-120°C and a vacuum degree of 0.08-0.1MPa for 2-2.5h, cool to 40-50°C, add acrylate diol, reactive diluent and polymerization inhibitor, mix well, add isocyanate, heat to 80-85°C and react for 2-3h to obtain a polyurethane prepolymer, and store it in nitrogen;

[0022] 2) The filler, titanium dioxide and thixotropic agent are vacuum-baked for 1.5-2h at a vacuum degree of 0.08-0.1MPa and 110-115°C, and then the polyurethane prepolymer obtained in step 1) and the oxazolidine dehydrating agent are added, and vacuum stirring is continued for 30-60min at a stirring speed of 200-500r / min. Finally, an adhesion promoter, a catalyst and a photoinitiator are added, and vacuum stirring is continued for 30-60min at a stirring speed of 200-500r / min to obtain the product.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1) The UV-moisture dual-curing polyurethane sealant of the present invention can be cured by UV radiation or moisture, combining the advantages of UV radiation curing and moisture curing, overcoming the shortcomings of traditional single-component moisture-curing polyurethane sealants that cannot be quickly cured and positioned and are prone to bubbling, while solving the defect that traditional UV glue cannot be cured in the light-blocking area, achieving rapid curing while effectively broadening the scope of application;

[0025] 2) There are no free unsaturated double bonds in the system of the present invention. Compared with the traditional UV-moisture dual-curing system, it has lower odor and is more environmentally friendly. At the same time, it solves the problem of incompatibility between acrylate and polyurethane systems and improves the storage stability, mechanical properties and weather resistance of the sealant;

[0026] 3) The present invention uses 3-(trimethylsilane)-1,2-propylene glycol to graft the silicone segment to the polyurethane segment through the hydroxyl group, which gives the system excellent high and low temperature resistance and can meet the requirements of the glue used in more working conditions;

[0027] 4) The present invention uses a reactive diluent and does not contain a free diluent, which greatly improves the adhesive properties of the sealant. The polyurethane and acrylic acid segments are interpenetrated through hydroxyl groups and double bonds, which improves the adhesive strength. At the same time, the long carbon chain at the double bond end gives the system excellent toughness. DETAILED DESCRIPTION

[0028] The present invention is described below in conjunction with examples, which are only used to explain the present invention and are not used to limit the scope of the present invention.

[0029] Example 1

[0030] A method for preparing a UV-moisture dual-curing polyurethane sealant:

[0031] 1) Take 15 parts of 2000 molecular weight difunctional polyoxypropylene ether and 7 parts of 3-(trimethylsilyl)-1,2-propylene glycol and dehydrate them at 110-120°C and vacuum degree of 0.08-0.1MPa for 2.5 hours, cool to 50°C, add 5 parts of acrylate diol, 30 parts of reactive diluent and 0.1 parts of hydroquinone and mix well, add 20 parts of toluene-2,4-diisocyanate, heat to 80-85°C and react for 2-3 hours to obtain a polyurethane prepolymer, and store it in nitrogen;

[0032] 2) 20 parts of light calcium carbonate, 80 parts of heavy calcium carbonate, 10 parts of titanium dioxide, and 4 parts of fumed silica were baked at a vacuum degree of 0.08-0.1 MPa and 110-115° C. for 1.5-2 h, and the temperature was lowered to obtain a mixture; 100 parts of a polyurethane prepolymer and 5 parts of an oxazolidine dehydrating agent ALT201 were added to the mixture, and the mixture was stirred in vacuum for 30 min at a stirring speed of 200 r / min to obtain a mixture; 5 parts of KBM-1083, 1 part of dibutyltin dilaurate, 2 parts of a bismorpholine diethyl ether catalyst, and 3 parts of a 184 photoinitiator were quickly added to the mixture, and the mixture was stirred in vacuum for 60 min at a stirring speed of 200 r / min to obtain a UV-moisture dual-curing system polyurethane sealant.

[0033] Example 2

[0034] A method for preparing a UV-moisture dual-curing polyurethane sealant:

[0035] 1) Take 40 parts of 4000 molecular weight difunctional polyoxypropylene ether and 5 parts of 3-(trimethylsilyl)-1,2-propylene glycol and dehydrate them at 110-120°C and vacuum degree of 0.08-0.1MPa for 2.5 hours, cool to 50°C, add 5 parts of acrylate diol, 10 parts of reactive diluent and 0.3 parts of p-tert-butylcatechol, mix well, add 17 parts of toluene diisocyanate, heat to 80-85°C and react for 2-3 hours to obtain a polyurethane prepolymer, and store it in nitrogen;

[0036] 2) 30 parts of light calcium carbonate, heavy calcium carbonate, 20 parts of talc, 5 parts of titanium dioxide, and 2 parts of organic bentonite are baked at a vacuum degree of 0.08-0.1 MPa and 115° C. for 2 hours, and the temperature is lowered to obtain a mixture; 100 parts of polyurethane prepolymer and 1 part of oxazolidine dehydrating agent ALT201 are added to the mixture, and the mixture is stirred in vacuum for 30 minutes at a stirring speed of 500 r / min to obtain a mixture; 2 parts of KBM-1083, 0.5 parts of stannous octoate, 0.5 parts of bismorpholine diethyl ether catalyst, and 1 part of 1173 photoinitiator are quickly added to the mixture, and the mixture is stirred in vacuum for 60 minutes at a stirring speed of 500 r / min to obtain a UV-moisture dual-curing system polyurethane sealant.

[0037] Example 3

[0038] A method for preparing a UV-moisture dual-curing polyurethane sealant:

[0039] 1) Take 10 parts of difunctional polyoxypropylene ether with a molecular weight of 2000, 20 parts of difunctional polyoxypropylene ether with a molecular weight of 4000, and 5 parts of 3-(trimethylsilyl)-1,2-propylene glycol, dehydrate them at 110-120°C and a vacuum degree of 0.08-0.1MPa for 2.5 hours, cool to 50°C, add 5 parts of acrylate diol, 20 parts of reactive diluent, 0.1 parts of p-tert-butylcatechol and 0.1 parts of cresol, mix well, add 20 parts of isophorone diisocyanate, heat to 80-85°C, react for 2-3 hours, obtain a polyurethane prepolymer, and store it in nitrogen;

[0040] 2) 40 parts of heavy calcium carbonate, 20 parts of talc, 8 parts of titanium dioxide, 10 parts of light calcium carbonate, and 3 parts of organic bentonite were baked at 110° C. under vacuum conditions of 0.08-0.1 MPa for 2 hours, and then cooled to obtain a mixture; 100 parts of polyurethane prepolymer and 4 parts of oxazolidine dehydrating agent ALT201 were added to the mixture, and the mixture was stirred in vacuum for 60 minutes at a stirring speed of 200 r / min to obtain a mixture; 3 parts of KBM-1083, 1.5 parts of bismorpholine diethyl ether catalyst, and 2 parts of 1173 photoinitiator were quickly added to the mixture, and the mixture was stirred in vacuum for 30 minutes at a stirring speed of 200 r / min to obtain a UV-moisture dual-curing system polyurethane sealant.

[0041] Comparative Example 1

[0042] Compared with Example 3, dipropylene glycol was used instead of 3-(trimethylsilyl)-1,2-propanediol.

[0043] Comparative Example 2

[0044] Compared with Example 3, the reactive diluent is replaced by a non-reactive diluent.

[0045] Comparative Example 3

[0046] Compared with Example 3, acrylate diol was replaced by acrylate.

[0047] The acrylic acid diol used in Examples 1-3 has the following structure:

[0048]

[0049] The reactive diluent used is Uitra LITE2020 produced by Cardolite Chemicals, which has the following structure:

[0050]

[0051] The polyurethane sealants obtained in Examples 1-3 were dispensed with a glue gun, and then UV-cured and UV-moisture-cured at room temperature, respectively. The following tests were performed, and the results are shown in Tables 1 and 2.

[0052] Table 1. UV curing indicators

[0053]

[0054] Table 2. UV+Moisture Curing Specifications

[0055]

[0056] Note:

[0057] The test execution standards of Table 1 and Table 2 are as follows:

[0058] 1. UV curing time: Place the sample 10 cm below the light source and irradiate it with UV light intensity of 55 mW / cm 2 , until the sample surface is no longer sticky.

[0059] 2. Hardness: Tested according to GBT2411-2008.

[0060] 3. Tensile strength and elongation at break: Test according to GB / T30776-2014. Place the mold on the foil, inject the sealant into the mold with a glue gun, scrape it flat with a scraper, remove the excess sealant, and remove the mold from the foil. The thickness of the glue layer is 2.5-3.0 mm. Curing under UV light for 30 seconds or first curing under UV light for 30 seconds, then curing for 168 hours at a temperature of (23±1)℃ and humidity of (50±5)%RH, take out the film, and cut it into dumbbell-shaped test pieces of the specified size. Test the tensile strength and elongation at room temperature at a tensile speed of (5±0.2) mm / s.

[0061] 4. Tensile shear strength: Tested according to GB / T7124-2008. The overlap length of the standard sample is (12.5±0.25) mm, and the thickness of the bonding layer is 0.2 mm. The FRP test piece needs to be evenly polished with corundum sandpaper, wiped clean with ethyl acetate, dried at 105-110°C, and placed in a dryer for use. Cured under UV light for 30 seconds or first cured under UV light for 30 seconds, then cured for 168 hours at a temperature of (23±1)°C and humidity of (50±5)% RH before testing.

[0062] It can be seen from the data in Tables 1 and 2 that the UV-moisture dual-curing polyurethane sealant of the present invention can obtain high tensile shear strength within tens of seconds under light radiation, which greatly saves positioning time; and has excellent mechanical properties after moisture curing, and the addition of unsaturated double bonds does not reduce the mechanical properties and molecular flexibility of the system.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A UV-moisture dual-curing polyurethane sealant, characterized in that: The composition comprises the following components in parts by weight: 100 parts of polyurethane prepolymer, 50-100 parts of filler, 5-10 parts of titanium dioxide, 2-5 parts of thixotropic agent, 1-5 parts of oxazolidine dewatering agent, 1-5 parts of adhesion promoter, 1-3 parts of catalyst, 1-3 parts of photoinitiator; The polyurethane prepolymer is prepared from 15-40 parts of polyether polyol, 5-10 parts of 3-(trimethylsilyl)-1,2-propylene glycol, 5-15 parts of acrylate diol, 10-20 parts of isocyanate, 10-30 parts of reactive diluent and 0.1-0.3 parts of inhibitor.

2. The UV-moisture dual-curing polyurethane sealant according to claim 1, characterized in that: The acrylate diol has the following molecular structure:

3. The UV-moisture dual-curing polyurethane sealant according to claim 1, characterized in that: The reactive diluent has the following molecular structure:

4. The UV-moisture dual-curing polyurethane sealant according to claim 1, characterized in that: The filler is one or a combination of light calcium carbonate, heavy calcium carbonate, and talcum powder; the thixotropic agent is one or two of fumed silica and organic bentonite; and the catalyst is one or a combination of two of dibutyltin dilaurate, stannous octoate, bismorpholine diethyl ether, and triethylenediamine.

5. The UV-moisture dual-curing polyurethane sealant according to claim 1, characterized in that: The adhesion promoter is a long-chain silane coupling agent KBM-1083 produced by Shin-Etsu of Japan; the photoinitiator is one or a combination of 184 photoinitiator and 1173 photoinitiator.

6. The UV-moisture dual-curing polyurethane sealant according to claim 1, characterized in that: The polymerization inhibitor is a combination of one or more of hydroquinone, p-tert-butylcatechol and cresol.

7. The UV-moisture dual-curing polyurethane sealant according to claim 1, characterized in that: The polyether polyol is a difunctional polyoxypropylene ether with a number average molecular weight of 2000-4000; the isocyanate is one or a combination of two of diphenylmethane diisocyanate, toluene diisocyanate and isophorone diisocyanate; the oxazolidine dewatering agent is ALT201 produced by Changde Elite New Materials Technology Co., Ltd.

8. A method for preparing the UV-moisture dual-curing polyurethane sealant according to any one of claims 1 to 7, characterized in that: The following steps are involved: 1) Dehydrate the polyether polyol and 3-(trimethylsilyl)-1,2-propylene glycol at 110-120°C and a vacuum degree of 0.08-0.1MPa for 2-2.5h, cool to 40-50°C, add acrylate diol, reactive diluent and inhibitor, mix well, add isocyanate, heat to 80-85°C and react for 2-3h to obtain a polyurethane prepolymer, and store it in nitrogen; 2) The filler, titanium dioxide and thixotropic agent are vacuum-baked for 1.5-2h at a vacuum degree of 0.08-0.1MPa and 110-115°C, and then the polyurethane prepolymer obtained in step 1) and the oxazolidine dehydrating agent are added, and vacuum stirring is continued for 30-60min at a stirring speed of 200-500r / min. Finally, an adhesion promoter, a catalyst and a photoinitiator are added, and vacuum stirring is continued for 30-60min at a stirring speed of 200-500r / min to obtain the product.

Images