Organic silicon modified polyether-polycarbonate waterborne polyurethane and preparation method thereof
Technical Field
The invention belongs to the technical field of waterborne polyurethane, and particularly relates to organic silicon modified polyether-polycarbonate waterborne polyurethane and a preparation method thereof.
Background
With the development and progress of society, petroleum resources are increasingly exhausted in large quantity, and the utilization of petrochemical resources can cause environmental pollution. Carbon dioxide is a rich and inexpensive carbon-resource, and the effective utilization of carbon dioxide is a breakthrough in the world today to get rid of the dependence on petroleum resources.
The polyols used in conventional waterborne polyurethanes are mainly polyester polyols and polyether polyols. The polyester polyurethane is poor in hydrolysis resistance, while the polyether polyurethane is poor in mechanical properties. Thus, polyether-polycarbonates resulting from the ring-opening copolymerization of carbon dioxide and propylene oxide have been produced.
Chinese patent document with application publication number CN 105566597A discloses carbon dioxide-based waterborne polyurethane, a preparation method and a coating, wherein the method comprises the steps of stirring and reacting carbon dioxide-based dihydric alcohol, polyester or polyether dihydric alcohol, diisocyanate and a carboxylic acid hydrophilic chain extender or an amine hydrophilic chain extender to obtain a polyurethane prepolymer with NCO at the tail end; then adding an alkaline or acidic neutralizing agent into the polyurethane prepolymer with NCO at the tail end and stirring to obtain a water-based polyurethane prepolymer; and finally, adding a polyamine chain extender into the waterborne polyurethane prepolymer to obtain the carbon dioxide-based waterborne polyurethane coating.
However, the carbon dioxide-based waterborne polyurethane coating prepared in the technical scheme has the defects of insufficient mechanical strength, poor water resistance and heat resistance and the like.
Disclosure of Invention
Aiming at the problems in the prior art, the invention discloses a preparation method of organic silicon modified polyether-polycarbonate waterborne polyurethane, and the prepared organic silicon modified polyether-polycarbonate waterborne polyurethane has excellent tensile strength, water resistance and heat resistance.
The specific technical scheme is as follows:
a preparation method of organic silicon modified polyether-polycarbonate waterborne polyurethane comprises the following steps:
(1) mixing an epoxy compound, carbon dioxide, an initiator, a catalyst A and an epoxy group-containing silane coupling agent, and reacting to prepare the organic silicon modified polyether-polycarbonate polyol;
the initiator is selected from polyhydroxy small molecules or polyhydroxy polymers;
(2) stirring and reacting the organic silicon modified polyether-polycarbonate polyol prepared in the step (1), diisocyanate, a polyhydroxy hydrophilic chain extender and a catalyst B to prepare a polyurethane prepolymer with an NCO group at the terminal;
(3) reacting the polyurethane prepolymer with the NCO group at the tail end prepared in the step (2) with an alkaline neutralizing agent to obtain a water-based polyurethane prepolymer;
(4) and (3) mixing the waterborne polyurethane prepolymer prepared in the step (3), water and a polyamine chain extender, and reacting to prepare the organic silicon modified polyether-polycarbonate waterborne polyurethane.
According to the invention, the epoxy silane coupling agent is added in the copolymerization reaction of the epoxy compound and carbon dioxide as a third reaction monomer, and the organosilicon modified polyether-polycarbonate polyol is obtained through copolymerization and is used as a soft segment to prepare the waterborne polyurethane, so that the water resistance, weather resistance and mechanical properties of the polyurethane film are improved.
In the step (1):
the epoxy compound is selected from the common classes, such as ethylene oxide or propylene oxide; preferably, the epoxide compound is selected from propylene oxide.
In step (1), the initiator simultaneously functions as a chain transfer agent and is selected from polyhydroxy small molecules or polyhydroxy polymers.
And the polyhydroxy small molecules such as propylene glycol and butanediol.
The polyhydroxy polymer is polyethylene glycol or polypropylene glycol.
Preferably, the initiator is selected from polypropylene glycol, and tests show that by using polypropylene glycol as the initiator and the chain transfer agent, on one hand, other chain segments can be introduced as little as possible, the chain segments of the product are more regular, and the molecular weight distribution is narrower; on the other hand, the properties are stable, the phase state is not influenced by the experiment temperature and pressure, and the experiment error is reduced.
More preferably, the number average molecular weight of the polypropylene glycol is 200 to 1000 g/mol. Tests show that the number average molecular weight of the organosilicon modified polyether-polycarbonate polyol prepared by using the polypropylene glycol with the number average molecular weight range as an initiator is moderate, and the mechanical property of the waterborne polyurethane film finally prepared by using the organosilicon modified polyether-polycarbonate polyol as a soft segment is better.
Preferably, the epoxy-containing silane coupling agent is selected from a commercially available silane coupling agent, KH 560.
Preferably:
the molar ratio of the epoxy compound, the initiator and the epoxy-containing silane coupling agent is 1:
(1-5)%: (5-15)%; the organic silicon content in the product organic silicon modified polyether-polycarbonate polyol can be regulated and controlled in a large range by adjusting the molar ratio of the epoxy compound to the epoxy-containing silane coupling agent; and the content of the organic silicon in the product organic silicon modified polyether-polycarbonate polyol can be regulated and controlled in a small range by adjusting the molar ratio of the epoxy compound to the initiator.
In the reactor, the pressure of the carbon dioxide is 2-5 MPa.
The catalyst A is selected from double metal cyanide complexes, such as zinc-cobalt double metal cyanide complexes;
the mass ratio of the epoxy compound to the catalyst A is 1: (0.01-0.1)%.
In the step (1), the ternary polymerization reaction is greatly influenced by the reaction temperature, preferably, the reaction temperature is 80-120 ℃, and tests show that when the reaction temperature is lower than 80 ℃, the organosilicon chain segment is basically not detected in the product. Further preferably, the reaction temperature is 100 ℃ and the reaction time is 5-24 h.
Further preferably:
the initiator is selected from polypropylene glycols having an average number average molecular weight of 400 g/mol;
the molar ratio of the epoxy compound, the initiator and the epoxy-containing silane coupling agent is 1: (1.19-4.26)%: 7.5 percent.
Tests show that the number average molecular weight of the prepared organic silicon modified polyether-polycarbonate polyol is 1500-4000 g/mol by using polypropylene glycol with the number average molecular weight of 400g/mol as an initiator; meanwhile, the molar ratio of an epoxy compound, an initiator and a silane coupling agent containing an epoxy group is 1: (1.19-4.26)%: and when 7.5 percent of the total organic silicon content is obtained, the content of organic silicon chain segments in the prepared organic silicon modified polyether-polycarbonate polyol is 3.6-5.4 percent.
In the step (2):
the diisocyanate is selected from at least one of 2, 4-toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate and 1, 6-hexamethylene diisocyanate;
the polyhydroxy hydrophilic chain extender is selected from 2, 2-dimethylolpropionic acid and/or 2, 2-dimethylolbutyric acid;
the catalyst B is preferably dibutyltin dilaurate;
the molar ratio of the diisocyanate to the organosilicon modified polyether-polycarbonate polyol to the polyhydroxy hydrophilic chain extender is 1: (15-40)%: (20-40)%;
the mass ratio of the diisocyanate to the catalyst B is 1: (0.01-0.1)%;
the reaction temperature is 75-85 ℃, and the reaction time is 1.5-3 h.
In the step (3):
the alkaline neutralizing agent is selected from triethylamine, ammonia water or sodium hydroxide;
the molar ratio of the alkaline neutralizing agent to the polyhydroxy hydrophilic chain extender is 1: 0.8 to 1.1;
the reaction temperature is 30-45 ℃, and the reaction time is 20-40 min.
In the step (4):
the polyamine chain extender is selected from at least one of ethylenediamine, 1, 3-propanediamine and 1, 4-butanediamine;
the molar ratio of the polyamine chain extender to the diisocyanate is 1: 1.6 to 3.3;
the mass ratio of the waterborne polyurethane prepolymer to water is (25-60): 100, respectively;
the reaction temperature is 15-30 ℃, and the reaction time is 1-2 h.
The reaction formula of the whole preparation process is shown as the following formula:
further preferably:
in the step (1):
the molar ratio of the epoxy compound, the initiator and the epoxy-containing silane coupling agent is 1: (3.41-4.26)%: 7.5 percent;
in the step (2):
the molar ratio of the diisocyanate to the organosilicon modified polyether-polycarbonate polyol to the polyhydroxy hydrophilic chain extender is 1: (20-26)%: (22-26)%;
in the step (3):
the molar ratio of the alkaline neutralizing agent to the polyhydroxy hydrophilic chain extender is 1: 1;
in the step (4):
the molar ratio of the polyamine chain extender to the diisocyanate is 1: 1.83 to 1.91.
Tests show that the organic silicon modified polyether-polycarbonate waterborne polyurethane prepared by the process has better mechanical property.
Still more preferably:
in the step (1):
the molar ratio of the epoxy compound, the initiator and the epoxy-containing silane coupling agent is 1: 4.26%: 7.5 percent;
in the step (2):
the molar ratio of the diisocyanate to the organosilicon modified polyether-polycarbonate polyol to the polyhydroxy hydrophilic chain extender is 1: 25.9%: 22.7 percent;
in the step (3):
the molar ratio of the alkaline neutralizing agent to the polyhydroxy hydrophilic chain extender is 1: 1;
in the step (4):
the molar ratio of the polyamine chain extender to the diisocyanate is 1: 1.91.
tests show that the organosilicon modified polyether-polycarbonate waterborne polyurethane prepared by the process has excellent tensile strength, water resistance and heat resistance.
The invention also discloses the organosilicon modified polyether-polycarbonate waterborne polyurethane prepared by the method, and the structural general formula is as follows
In the formula:
R2Is selected from-CH2CH2—、—CH2CH2CH2-or-CH2CH2CH2CH2—;
R
3Is selected from
NH
4Or Na;
R
4is selected from
Wherein x is 1-15, y is 1-60, and z is 1-5.
Compared with the prior art, the invention has the following beneficial effects:
the invention discloses a preparation method of organic silicon modified polyether-polycarbonate waterborne polyurethane, which comprises the steps of adding an epoxy silane coupling agent as a third reaction monomer in a copolymerization reaction of an epoxy compound and carbon dioxide, copolymerizing to obtain organic silicon modified polyether-polycarbonate polyol, and using the organic silicon modified polyether-polycarbonate polyol as a soft segment to prepare the waterborne polyurethane, so that the water resistance, the heat resistance and the mechanical property of a polyurethane film are improved.
Drawings
FIG. 1 is a nuclear magnetic hydrogen spectrum of a silicone-modified polyether-polycarbonate polyol prepared in example 2;
FIG. 2 is an IR spectrum of the silicone-modified polyether-polycarbonate polyol prepared in example 2 and shows, for comparison, an IR spectrum of PPG-2000 versus the polyether-polycarbonate polyol prepared in comparative example 1;
FIG. 3 is a comparison graph of infrared spectra of waterborne polyurethanes prepared in example 2 and comparative examples 1-2, respectively;
FIG. 4 is a stress-strain curve of the organosilicon modified polyether-polycarbonate waterborne polyurethane prepared in examples 1-4 respectively;
FIG. 5 is a stress-strain curve of the aqueous polyurethane prepared in example 2 and comparative examples 1 to 2, respectively.
Detailed Description
To further clarify the objects, technical solutions and advantages of the present invention, the following detailed description of the present invention is provided with reference to specific examples, which should not be construed as limiting the scope of the present invention.
Example 1
Step 1: preparation of organosilicon modified polyether-polycarbonate polyols
Before the reaction started, a 100mL stainless steel autoclave was purged and dried under vacuum at 80 ℃ for 2h to remove the water from the autoclave. 34.08g (0.587mol) of propylene oxide, 10.4g (0.044mol) of KH560, 10.0g (0.025mol) of PPG-400 and 20mg of zinc-cobalt double metal cyanide complex were charged into a reaction vessel, which was charged with a small amount of CO2And the temperature is raised to 100 ℃ and then CO is adjusted2The pressure is 5MPa, and the reaction is carried out for 12 h. After the reaction is finished, cooling the reaction kettle in an ice-water bath, and slowly releasing the gas in the kettle at normal temperature. The crude product was dissolved with 20mL of dichloromethane and then precipitated in 150mL of n-hexane to give the organosilicon-modified polyether-polycarbonate polyol.
The number average molecular weight of the product was 1500g/mol, PDI was 1.7, carbonate content was 13.5 mol%, and silicone segment content was 3.6 mol%.
Step 2: preparation of organic silicon modified polyether-polycarbonate waterborne polyurethane
Adding 8.5g (0.0057mol) of the organic silicon modified polyether-polycarbonate polyol prepared in the step 1, 0.71g (0.005mol) of 2, 2-dimethylolpropionic acid and 0.001g of dibutyltin dilaurate catalyst into a 250mL four-neck flask, heating to 80 ℃, slowly dropwise adding 5g (0.022mol) of isophorone diisocyanate into the flask, reacting for 2h after dropwise adding, cooling to 40 ℃, adding 0.54g (0.005mol) of triethylamine, reacting for 0.5h, adding 10.8g of deionized water, cooling to 25 ℃, adding 25.2g (1.4mol) of deionized water and 0.69g (0.0115mol) of ethylenediamine, stirring for 1h at 600rpm, pouring into a tetrafluoroethylene mold, and curing for 48 h at 40 ℃ to obtain the organic silicon modified polyether-polycarbonate waterborne polyurethane, which is marked as WPU 1.
The tensile strength of the organosilicon-modified polyether-polycarbonate aqueous polyurethane prepared in this example was tested according to the method specified in GB/T1040.1-2006. The test data are listed in table 1 below.
Example 2
Step 1: preparation of organosilicon modified polyether-polycarbonate polyol
The preparation was carried out in the same manner as in step 1 of example 1 except that the amount of PPG-400 was changed to 8.1g (0.02mol) to obtain an organosilicon-modified polyether-polycarbonate polyol having a number average molecular weight of 2200g/mol, PDI of 2.0, a carbonate content of 17.1 mol% and an organosilicon segment content of 4.1 mol%.
Step 2: preparation of organic silicon modified polyether-polycarbonate waterborne polyurethane
Adding 10g (0.0045mol) of the organic silicon modified polyether-polycarbonate polyol prepared in the step 1, 0.79g (0.0056mol) of dimethylolpropionic acid and 0.001g of dibutyltin dilaurate catalyst into a 250mL four-neck flask, heating to 80 ℃, slowly dropwise adding 5g (0.022mol) of isophorone diisocyanate into the flask, reacting for 2h after dropwise adding, cooling to 40 ℃, adding 0.60g of triethylamine (0.0056mol), reacting for 0.5h, adding 12.0g of deionized water, cooling to 25 ℃, adding 27.9g of deionized water and 0.72g (0.012mol) of ethylenediamine, stirring for 1h at 600rpm, pouring into a tetrafluoroethylene mold, and curing for 48 h at 40 ℃ to obtain the organic silicon modified polyether-polycarbonate waterborne polyurethane, which is marked as WPU 2.
The tensile strength of the organosilicon-modified polyether-polycarbonate aqueous polyurethane prepared in this example was tested according to the method specified in GB/T1040.1-2006. The test data are listed in table 1 below. The water and heat resistance data for the products prepared in this example are set forth in Table 2 below.
Example 3
Step 1: preparation of organosilicon modified polyether-polycarbonate polyols
The preparation was carried out in the same manner as in step 1 of example 1 except that the amount of PPG-400 was changed to 5.9g (0.015mol) to obtain an organosilicon-modified polyether-polycarbonate polyol having a number average molecular weight of 3100g/mol, PDI of 2.2, a carbonate content of 21.9 mol% and a silicone segment content of 4.6 mol%.
Step 2: preparation of organic silicon modified polyether-polycarbonate waterborne polyurethane
Adding 12g (0.0039mol) of the organic silicon modified polyether-polycarbonate polyol prepared in the step 1, 0.89g (0.0063mol) of dimethylolpropionic acid and 0.001g of dibutyltin dilaurate catalyst into a 250mL four-neck flask, heating to 80 ℃, slowly dropwise adding 5g (0.022mol) of isophorone diisocyanate into the flask, reacting for 2h after dropwise adding, cooling to 40 ℃, adding 0.67g (0.0063mol) of triethylamine, reacting for 0.5h, adding 13.5g of deionized water, cooling to 25 ℃, adding 31.5g of deionized water and 0.72g (0.012mol) of ethylenediamine, stirring for 1h at 600rpm, pouring into a tetrafluoroethylene mold, and curing for 48 h at 40 ℃ to obtain the organic silicon modified polyether-polycarbonate waterborne polyurethane, which is marked as WPU 3.
The tensile strength of the organosilicon-modified polyether-polycarbonate aqueous polyurethane prepared in this example was tested according to the method specified in GB/T1040.1-2006. The test data are listed in table 1 below.
Example 4
Step 1: preparation of organosilicon modified polyether-polycarbonate polyols
The preparation method was the same as in step 1 of example 1, except that the mass of PPG-400 was changed to 2.7g (0.007mol), to obtain an organosilicon-modified polyether-polycarbonate polyol having a number average molecular weight of 3900 g/mol, PDI of 2.5, a carbonate content of 12.0 mol% and an organosilicon segment content of 5.4 mol%.
Step 2: preparation of organic silicon modified polyether-polycarbonate waterborne polyurethane
Adding 14g (0.0036mol) of the organic silicon modified polyether-polycarbonate polyol prepared in the step 1, 0.89g (0.0063mol) of dimethylolpropionic acid and 0.001g of dibutyltin dilaurate catalyst into a 250mL four-neck flask, heating to 80 ℃, slowly dropwise adding 5g (0.022mol) of isophorone diisocyanate into the flask, reacting for 2h after dropwise adding, cooling to 40 ℃, adding 0.67g (0.0063mol) of triethylamine, reacting for 0.5h, adding 13.5g of deionized water, cooling to 25 ℃, adding 31.5g of deionized water and 0.72g (0.012mol) of ethylenediamine, stirring for 1h at 600rpm, pouring into a tetrafluoroethylene mold, and curing for 48 h at 40 ℃ to obtain the organic silicon modified polyether-polycarbonate waterborne polyurethane, which is marked as WPU 4.
The tensile strength of the organosilicon-modified polyether-polycarbonate aqueous polyurethane prepared in this example was tested according to the method specified in GB/T1040.1-2006. The test data are listed in table 1 below.
Comparative example 1
Step 1: preparation of polyether-polycarbonate polyols
The preparation process was analogous to step 1 in the example, and compared with example 2, only the reactants were changed to 34.08g of propylene oxide and 8.1g of PPG-400 without adding KH560 to give a product of polyether-polycarbonate polyol having a number average molecular weight of 1900g/mol, PDI of 1.6 and a carbonate content of 14.9 mol%.
Step 2: preparation of polyether-polycarbonate waterborne polyurethane
Adding 10g of polyether-polycarbonate polyol prepared in the step 1, 0.79g of dimethylolpropionic acid and 0.001g of dibutyltin dilaurate catalyst into a 250mL four-neck flask, heating to 80 ℃, slowly dropwise adding 5g of isophorone diisocyanate into the flask, reacting for 2h after dropwise adding, cooling to 40 ℃, adding 0.60g of triethylamine, reacting for 0.5h, adding 11.9g of deionized water, cooling to 25 ℃, adding 27.9g of deionized water and 0.68g of ethylenediamine, stirring at 600rpm for 1h, pouring into a tetrafluoroethylene mold, and curing at 40 ℃ for 48 h to obtain polyether-polycarbonate waterborne polyurethane, which is marked as WPU-DB 1.
The polyether-polycarbonate aqueous polyurethane prepared in the present comparative example was tested for tensile strength according to the method specified in GB/T1040.1-2006. The test data are listed in table 1 below.
The water and heat resistance data for the product prepared in this comparative example are listed in table 2 below.
Comparative example 2
Adding 10g of PPG-2000, 0.79g of dimethylolpropionic acid and 0.001g of dibutyltin dilaurate catalyst into a 250mL four-neck flask, heating to 80 ℃, slowly dropwise adding 5g of isophorone diisocyanate into the flask, reacting for 2h after dropwise adding, cooling to 40 ℃, adding 0.60g of triethylamine, reacting for 0.5h, adding 12.0g of deionized water, cooling to 25 ℃, adding 27.9g of deionized water and 0.70g of ethylenediamine, stirring at 600rpm for 1h, pouring into a tetrafluoroethylene mold, and curing at 40 ℃ for 48 h to obtain the PPG waterborne polyurethane, WPTAU-DB 2.
The tensile strength of the aqueous polyurethane prepared in this comparative example was tested according to the method specified in GB/T1040.1-2006. The test data are listed in table 1 below. The water and heat resistance data for the product prepared in this comparative example are listed in table 2 below.
TABLE 1
TABLE 2
As can be seen from a comparison of the data in Table 2, the products prepared in the examples have better water resistance and heat resistance than the products prepared in comparative examples 1 to 2, respectively. The organosilicon modified polyether-polycarbonate waterborne polyurethane prepared by the method disclosed by the invention has better tensile strength, water resistance and heat resistance.