CN111117549B

CN111117549B - Single-component polyurethane sealant prepared by using PAPI (polymethylacrylate polyimide)

Info

Publication number: CN111117549B
Application number: CN201911373652.9A
Authority: CN
Inventors: 阮军; 李宏伟; 田益
Original assignee: Yuzhongqing Waterproof Technology Group Co ltd
Current assignee: Yuzhongqing Waterproof Technology Group Co ltd
Priority date: 2019-12-27
Filing date: 2019-12-27
Publication date: 2022-01-28
Anticipated expiration: 2039-12-27
Also published as: CN111117549A

Abstract

The invention discloses a single-component polyurethane sealant prepared by PAPI (polymethylene polyphenyl polyisocyanate), which mainly comprises 25-35% of first polypropylene oxide dihydric alcohol, 0-10% of second polypropylene oxide dihydric alcohol, 1.2-1.7% of PAPI, 0.6-2.2% of diisocyanate, 15-25% of plasticizer, 25-45% of filler, 1-2% of pigment, 0.2-0.6% of catalyst, 0.5-1.0% of antioxidant, 0.5-1.0% of ultraviolet absorbent, 1.0-3.0% of adhesion promoter, 2.0-3.0% of physical water removing agent, 1.0-3.0% of chemical water removing agent, 1.0-2.0% of thixotropic curing agent and 2-3% of thixotropic agent, wherein the sealant is polymerized step by step in the preparation process, the PAPI can fully react with the polyether polyol, the unreacted isocyanate functional group in the PAPI in the final curing process of the sealant is reduced, the defect that the PAPI cannot be applied to polyurethane sealant/waterproof coating with moderate curing speed due to too high reaction speed is overcome, and the prepared sealant has low modulus, good elasticity and excellent durability.

Description

Single-component polyurethane sealant prepared by using PAPI (polymethylacrylate polyimide)

Technical Field

The invention relates to a single-component polyurethane sealant prepared by using PAPI, and relates to the field of adhesives.

Background

The single-component polyurethane sealant is widely applied as an adhesive product, has high use convenience and wide mechanical adjustable range due to good bonding effect, and has widely accepted application effect at present. The different isocyanate properties endow different use characteristics to products, such as lower viscosity of polyurethane sealant prepared from toluene diisocyanate, better scraping performance and sending-out performance, better bonding effect of the sealant prepared from diphenylmethane diisocyanate, lower odor, good aging resistance of the sealant prepared from hexamethylene diisocyanate because the hexamethylene diisocyanate does not contain benzene rings, excellent yellowing resistance of the sealant prepared from isophorone diisocyanate, and different product use requirements can be met by products with different performance, however, the polymethylene polyphenyl polyisocyanate (PAPI) occupying larger isocyanate yield can quickly react with a curing agent and is cured within 1-2min because the polymethylene polyphenyl polyisocyanate (PAPI) has higher reaction speed with the polyether polyol and the curing agent, so that the method is widely applied to the production process of foamed polyurethane products, and is not suitable for polyurethane sealant and building polyurethane waterproof coating material which have certain requirements on curing and reaction time And the like.

Disclosure of Invention

The invention aims to solve the problem that the polyurethane prepolymer prepared by using the PAPI at present cannot meet the use characteristics of a polyurethane sealant and a polyurethane waterproof coating. By the adoption of the step-by-step synthesis process of the selection of the polyoxypropylene diol and the prepolymer, the PAPI and the low-activity medium molecular weight polyoxypropylene diol preferentially react at a lower temperature, the amount of-NCO in unreacted PAPI in a final product is reduced, and the curing process of the sealant is still formed by means of moisture curing of the-NCO in the subsequently added diisocyanate. The PAPI with high yield and low cost is introduced into the processing field of the polyurethane sealant, and the usage amount of other high-cost special isocyanate in the processing process of the polyurethane sealant is reduced.

In order to solve the problems, the invention discloses a single-component polyurethane sealant prepared by PAPI, which is realized by the following technical scheme.

A single-component polyurethane sealant prepared from PAPI (polymethylene polyphenyl polyisocyanate) mainly comprises 20-35% of first polypropylene oxide glycol, 0-10% of second polypropylene oxide glycol, 1.4-2.2% of PAPI, 2.2-3.6% of diisocyanate, 15-25% of plasticizer, 25-45% of filler, 1-2% of pigment, 0.2-0.6% of catalyst, 0.5-1.0% of antioxidant, 0.5-1.0% of ultraviolet absorbent, 1.0-3.0% of adhesion promoter, 2.0-3.0% of physical water remover, 1.0-3.0% of chemical water remover, 1.0-2.0% of latent curing agent and 2-3% of thixotropic agent.

In the invention: the molecular weight of the first polyoxypropylene diol is 4000-8000. The molecular weight of the second polypropylene oxide glycol is between 1000-2000.

The PAPI is polyphenyl polymethylene polyisocyanate containing 40-50% of diisocyanate (MDI), 30-40% of tribasic isocyanate and 10-25% of tetrabasic and above isocyanate, wherein the molar weight ratio of 2-NCO to 4-NCO is 2-8 to 3-7. Contains a molar ratio of-NCO to-OH in the first polyoxypropylene diol of 0.9-1.4: 1.

in the invention: the physical water removing agent is one or a mixture of two of 4A type molecular sieve activation powder or 5A type molecular sieve activation powder, and the chemical water removing agent is a beta type silane coupling agent without amino and hydroxyl functional groups.

In the invention: the diisocyanate is one or a mixture of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate.

In the invention: the catalyst is one or a mixture of stannous octoate, dibutyltin dilaurate, monobutyl tin trioctoate and dibutyltin bis (acetyl acetonate).

The filler is one or a mixture of more of nano calcium carbonate, precipitated barium sulfate, titanium dioxide, zinc oxide, heavy calcium carbonate, light calcium carbonate, talcum powder and kaolin

The plasticizer is one or a mixture of more of diisodecyl phthalate, diisononyl phthalate, di (2-ethylhexyl) phthalate, epoxidized soybean oil and synthetic vegetable ester.

The thixotropic agent is one or a mixture of more of hydrophobic modified gas phase silica, modified flaky organic bentonite, modified polyamide wax and attapulgite.

The preparation method of the sealant comprises the following steps:

the method comprises the following steps: adding the first polyoxypropylene diol and the plasticizer into a mixer according to the formula amount, stirring, vacuumizing and dehydrating, keeping the temperature at 50-80 ℃, adding PAPI in batches, adding the second polyoxypropylene diol, reacting for 0.5-3h, stopping stirring, and defoaming in vacuum to obtain the first reaction product.

Step two: and (3) stirring the first reaction product, heating to 80-100 ℃, adding the formula amount of diisocyanate, reacting until the NCO% of the material is sampled and titrated to meet the formula design requirement, and stopping heating to obtain the polyurethane prepolymer.

Step three: and adding the pre-dried powder, pigment and physical dehydrating agent into the polyurethane prepolymer generated by the reaction in the second step, and stirring to uniformly mix the mixture to obtain a third mixture.

Step four: adding thixotropic agent into the mixture produced in the third step, and stirring while keeping the temperature to obtain a fourth mixture

Step five: and (3) cooling the mixture generated by the fourth step, adding the antioxidant, the ultraviolet absorbent, the adhesion promoter and the chemical water removal agent in the formula amount, stirring to uniformly mix the mixture, adding the catalyst and the latent curing agent in the formula amount, vacuumizing, and stirring to obtain the single-component polyurethane sealant.

Preferably, the preparation method of the sealant comprises the following steps:

the method comprises the following steps: adding a first polyoxypropylene diol and a plasticizer in a formula amount into a mixer, stirring at the temperature of 110-120 ℃, vacuumizing and dehydrating, keeping the vacuum degree to be less than or equal to-0.09 Mpa, reducing the temperature to 60-65 ℃ when the moisture content is less than or equal to 0.005 percent, adding PAPI accounting for 50 percent of the formula amount, keeping the temperature at 60-65 ℃ for reaction for 0.5h, adding PAPI accounting for 30 percent of the formula amount for reaction for 0.5h, adding PAPI accounting for 20 percent of the formula amount and a second polyoxypropylene diol, reacting for 1h, stopping stirring, and carrying out vacuum deaeration for 0.5 h. Thus obtaining the first reaction product.

Step two: stirring the first reaction product, heating to 80-90 ℃, adding a formula amount of diisocyanate, keeping the temperature at 80-90 ℃ for reaction for 2-2.5h, and stopping heating when the NCO% of the material is sampled and titrated to meet the formula design requirement, thus obtaining the polyurethane prepolymer.

Step three: and adding the pre-dried powder material with the water content of less than or equal to 0.05 percent, the pigment and the physical dehydrating agent into the polyurethane prepolymer generated by the reaction in the second step, and stirring for 30min to uniformly mix the materials to obtain a third mixture.

Step four: adding a thixotropic agent into the mixture produced in the third step, keeping the temperature at 80-90 ℃, and mixing and stirring for 40-60min at the stirring speed of 600-800r/min to activate and uniformly mix the thixotropic agent, thereby obtaining a fourth mixture.

Step five: and (3) reducing the temperature of the mixture generated by the fourth step reaction to below 55 ℃, adding an antioxidant, an ultraviolet absorbent, an adhesion promoter and a chemical water removal agent in a formula amount, stirring for 30min to uniformly mix the mixture, adding a catalyst and a latent curing agent in a formula amount, vacuumizing and keeping the vacuum degree to be less than or equal to-0.09 Mpa, and stirring for 10min to obtain the single-component polyurethane sealant.

Detailed Description

For a better understanding of the inventive nature of the present invention, reference is made to the following examples.

Example 1:

a single-component polyurethane sealant prepared by using PAPI comprises the following components in a specific processing mode:

wherein the molecular weight of the first polyoxypropylene diol is 5000, the molecular weight of the second polyoxypropylene diol is 2000, the ultraviolet absorber is UV531 of basf chemistry, the antioxidant is TINUVIN-B75 of basf chemistry, the latent curing agent is ALT-401 of Airit chemical industry, the thixotropic agent 1 is hydrophobic fumed silica R974 of Germany chemical industry, and the thixotropic agent 2 is organic bentonite SD-2 of Haimines chemistry.

In the embodiment, the single-component polyurethane sealant is prepared by the following method:

Example 2:

wherein the molecular weight of the first polypropylene oxide dihydric alcohol is 8000, the molecular weight of the second polypropylene oxide dihydric alcohol is 1000, the ultraviolet absorbent is UV1260 of basf chemistry, the antioxidant is TINUVIN-B75 of basf chemistry, the latent curing agent is CH-2 of ash and Hao chemistry, and the thixotropic agent is Crayvallac SLX of France Crayvallac corporation.

Example 3:

wherein the molecular weight of the first polypropylene oxide dihydric alcohol is 6000, the molecular weight of the second polypropylene oxide dihydric alcohol is 1000, the ultraviolet absorbent is UV1260 of Pasf chemical, the antioxidant is pentaerythritol tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], the latent curing agent is CH-2 of ash and Hao chemical, and the thixotropic agent is Crayvallac SLX of France Crayvallac company.

the method comprises the following steps: adding a first polyoxypropylene glycol and a plasticizer in a formula amount into a mixer, stirring at the temperature of 110-120 ℃, vacuumizing and dehydrating, keeping the vacuum degree to be less than or equal to-0.09 Mpa, reducing the temperature to 60-65 ℃ when the moisture content is less than or equal to 0.005 percent, adding PAPI accounting for 50 percent of the formula amount, keeping the temperature at 60-65 ℃ for reaction for 0.5h, adding PAPI accounting for 30 percent of the formula amount, reacting for 0.5h, adding PAPI accounting for 20 percent of the formula amount, reacting for 1h, stopping stirring, and defoaming for 0.5h in vacuum. Thus obtaining the first reaction product.

Step two: stirring the first reaction product, heating to 80-90 ℃, adding a formula amount of diisocyanate, keeping the temperature at 80-90 ℃ for reaction for 2.5h, and stopping heating when the NCO% of the material is sampled and titrated to meet the formula design requirement, thus obtaining the polyurethane prepolymer.

Comparative example 1:

In the comparative example, the single-component polyurethane sealant is prepared by the following method:

the method comprises the following steps: adding a first polyoxypropylene diol and a plasticizer in a formula amount into a mixer, stirring at the temperature of 110-120 ℃, vacuumizing and dehydrating, keeping the vacuum degree to be less than or equal to-0.09 Mpa, reducing the temperature to 60-65 ℃ when the moisture content is less than or equal to 0.005 percent, adding PAPI in the formula amount, keeping the temperature to be 60-65 ℃ for reaction for 0.5h, adding a second polyoxypropylene diol, reacting for 1h, stopping stirring, and defoaming in vacuum for 0.5 h. Thus obtaining the first reaction product.

Comparative example 2:

the method comprises the following steps: adding the first polyoxypropylene diol, the second polyoxypropylene diol and the plasticizer in the formula amount into a mixer, stirring at the temperature of 110-120 ℃, vacuumizing for dehydration, keeping the vacuum degree to be less than or equal to-0.09 Mpa, reducing the temperature to 80-90 ℃ when the moisture content is detected to be less than or equal to 0.005%, and adding the PAPI and the diisocyanate in the formula amount.

Step two: and adding the pre-dried powder material with the water content of less than or equal to 0.05 percent, the pigment and the physical dehydrating agent into the polyurethane prepolymer generated by the reaction in the second step, and stirring for 30min to uniformly mix the materials to obtain a third mixture.

Step three: adding a thixotropic agent into the mixture produced in the third step, keeping the temperature at 80-90 ℃, and mixing and stirring for 40-60min at the stirring speed of 600-800r/min to activate and uniformly mix the thixotropic agent, thereby obtaining a fourth mixture.

Step four: and (3) reducing the temperature of the mixture generated by the fourth step reaction to below 55 ℃, adding an antioxidant, an ultraviolet absorbent, an adhesion promoter and a chemical water removal agent in a formula amount, stirring for 30min to uniformly mix the mixture, adding a catalyst and a latent curing agent in a formula amount, vacuumizing and keeping the vacuum degree to be less than or equal to-0.09 Mpa, and stirring for 10min to obtain the single-component polyurethane sealant.

Comparative example 3:

Comparative example 4:

Comparative example 5:

The results of the tests of examples 1 to 4 and comparative examples 1 to 5 are as follows

TABLE 1 examination results of examples and comparative examples

The embodiment shows that the polyurethane sealant prepared by the invention has moderate viscosity, good construction convenience, good elasticity, low modulus and moderate curing time, and is suitable for various bonding operations of the building polyurethane sealant. Through comparison between the example 1 and the comparative example 1, it can be found that the sealant is prepared by adopting the process of completely adding the PAPI at one time to prepare the prepolymer instead of adopting a step method, the crosslinking density is increased due to excessive addition of the PAPI at one time, the reaction speed is too high, the viscosity of a rubber sample is increased, the curing time is obviously reduced, the modulus is too high, and the elastic recovery rate is poor. The comparison between the example 1 and the comparative example 2 shows that the viscosity of the rubber sample is also obviously increased by adding all the isocyanates together for polymerization, the curing time of the formula is extremely fast, the modulus is obviously increased, the elasticity is poor, more residual PAPI is not completely reacted with polyether and is reacted with moisture in the air, and the comparison between the example 1 and the comparative example 3 shows that when the addition amount of the PAPI is too large, the polyether in the material cannot completely react with the isocyanates in the PAPI, so that the curing speed of the sealant is too fast, the modulus is higher, and bubbles are more. Affecting its normal use. The comparison between example 1 and comparative example 4 shows that when the amount of the added powder is too large, the formula has the problems of greatly reduced elasticity, increased viscosity and slow curing speed, because the proportion of the prepolymer system is reduced too much, so that the system proportion is not adjusted and can not react to form a uniform elastomer. Comparison of example 1 with comparative example 5 shows that the viscosity of the formulation is too low when the plasticizer is added too much, and the film cannot be cured stably, because the film can be cured into a polyurethane system when the amount of the plasticizer added is too much.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the protection scope of the present invention, although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A single-component polyurethane sealant prepared from polymethylene polyphenyl polyisocyanate (PAPI) mainly comprises 20-35% of first polypropylene oxide glycol, 0-10% of second polypropylene oxide glycol, 1.4-2.2% of PAPI, 2.2-3.6% of diisocyanate, 15-25% of plasticizer, 35-45% of filler, 1-2% of pigment, 0.2-0.6% of catalyst, 0.5-1.0% of antioxidant, 0.5-1.0% of ultraviolet absorbent, 1.0-3.0% of adhesion promoter, 2.0-3.0% of physical water remover, 1.0-3.0% of chemical water remover, 1.0-2.0% of latent curing agent and 2-3% of thixotropic agent; the polyurethane sealant is reacted by adopting a method of adding isocyanate step by step in the preparation process;

the molecular weight of the first polyoxypropylene diol is between 4000-8000; the molecular weight of the second polypropylene oxide glycol is between 1000-2000;

the PAPI is polyphenyl polymethylene polyisocyanate containing 40-50% of diisocyanate, 30-40% of tribasic isocyanate and 10-25% of tetrabasic and above isocyanate, wherein the molar weight ratio of 2-NCO to 4-NCO is 2-8-3-7; contains a molar ratio of-NCO to-OH in the first polyoxypropylene diol of 0.9-1.4: 1;

the preparation method of the single-component polyurethane sealant comprises the following steps:

the method comprises the following steps: adding the first polyoxypropylene diol and the plasticizer into a mixer according to the formula amount, stirring, vacuumizing and dehydrating, keeping the temperature at 50-80 ℃, adding PAPI in batches, adding the second polyoxypropylene diol, reacting for 0.5-3h, stopping stirring, and defoaming in vacuum to obtain a first reaction product;

step two: stirring the first reaction product, heating to 80-100 ℃, adding a formula amount of diisocyanate, reacting until the NCO% of the material is sampled and titrated to meet the formula design requirement, and stopping heating to obtain a polyurethane prepolymer;

step three: adding the pre-dried powder, pigment and physical dehydrating agent into the polyurethane prepolymer generated by the reaction in the second step, and stirring to uniformly mix the materials to obtain a third mixture;

step four: adding a thixotropic agent into the mixture produced in the third step, and stirring at a constant temperature to obtain a fourth mixture;

2. The one-component polyurethane sealant according to claim 1, characterized in that: the physical water removing agent is one or a mixture of two of 4A type molecular sieve activation powder or 5A type molecular sieve activation powder, and the chemical water removing agent is a beta type silane coupling agent without amino and hydroxyl functional groups.

3. The one-component polyurethane sealant according to any one of claims 1 to 2, wherein: the diisocyanate is one or a mixture of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate.

4. The one-component polyurethane sealant according to any one of claims 1 to 2, wherein: the catalyst is one or a mixture of stannous octoate, dibutyltin dilaurate, monobutyl tin trioctoate and dibutyltin bis (acetyl acetonate); the filler is one or a mixture of more of nano calcium carbonate, precipitated barium sulfate, titanium dioxide, zinc oxide, heavy calcium carbonate, light calcium carbonate, talcum powder and kaolin; the plasticizer is one or a mixture of more of diisodecyl phthalate, diisononyl phthalate, di (2-ethylhexyl) phthalate, epoxidized soybean oil and synthetic vegetable ester; the thixotropic agent is one or a mixture of more of hydrophobic modified gas phase silica, modified flaky organic bentonite, modified polyamide wax and attapulgite.

5. The preparation method of the one-component polyurethane sealant according to one of claims 1 to 4, which is characterized in that:

the method comprises the following steps: adding a first polyoxypropylene diol and a plasticizer in a formula amount into a mixer, stirring at the temperature of 110-120 ℃, vacuumizing and dehydrating, keeping the vacuum degree to be less than or equal to-0.09 Mpa, reducing the temperature to 60-65 ℃ when the moisture content is less than or equal to 0.005% to be detected, adding PAPI accounting for 50% of the formula amount, keeping the temperature at 60-65 ℃ for reaction for 0.5h, adding PAPI accounting for 30% of the formula amount, reacting for 0.5h, adding PAPI accounting for 20% of the formula amount and a second polyoxypropylene diol, reacting for 1h, stopping stirring, and carrying out vacuum deaeration for 0.5h to obtain a first reaction product;

6. The preparation method of the one-component polyurethane sealant as claimed in claim 5, which is characterized in that:

step three: adding the pre-dried powder material with the water content less than or equal to 0.05 percent, the pigment and the physical dehydrating agent into the polyurethane prepolymer generated by the reaction in the second step, and stirring for 30min to uniformly mix the materials to obtain a third mixture;

7. The preparation method of the one-component polyurethane sealant as claimed in claim 6, which is characterized in that: