CN112159584A - Composite anti-condensation polyurethane sealing element and preparation method thereof - Google Patents

Abstract

The invention relates to the field of sealing elements, in particular to a composite anti-condensation polyurethane sealing element and a preparation method thereof, wherein the composite anti-condensation polyurethane sealing element comprises the following components in parts by weight: 50-80 parts of modified polyurethane, 10-30 parts of rubber, 2-5 parts of a flame retardant, 0.5-2 parts of an antioxidant, 1-3 parts of a wetting dispersant, 5-10 parts of a foaming agent, 0.5-1 part of an ultraviolet absorber and 5-12 parts of a vulcanizing agent. The composite anti-condensation polyurethane sealing element prepared by the invention has the advantages of good elasticity, good low-temperature flexibility, wear resistance, good cohesiveness and good mechanical strength of polyurethane, overcomes the defect of poor heat resistance of polyurethane, and greatly improves the properties of condensation resistance and acid and alkali resistance.

Description

Composite anti-condensation polyurethane sealing element and preparation method thereof

Technical Field

The invention relates to the field of sealing elements, in particular to a composite anti-condensation polyurethane sealing element and a preparation method thereof.

Background

Since the 80 s of the 20 th century, the mechanical, earthmoving equipment, electrical power applications industries began to use polyurethane as a seal material.

At present, a plurality of outdoor power equipment, especially power control and monitoring equipment, need to have the functions of heat preservation, water isolation and equipment condensation prevention, so that the sealant is also generated. At present, polyurethane sealant is mainly adopted for sealing, and the existing polyurethane sealant is widely applied due to good elasticity, good low-temperature flexibility, wear resistance, good adhesion to a base material and good mechanical strength, but has poor heat resistance, is easy to decompose at high temperature, and has poor anti-condensation effect, so that the use of the polyurethane sealant as some high-end sealing elements is limited.

Disclosure of Invention

Aiming at the problems, the invention provides a composite anti-condensation polyurethane sealing element which comprises the following components in parts by weight:

50-80 parts of modified polyurethane, 10-30 parts of rubber, 2-5 parts of a flame retardant, 0.5-2 parts of an antioxidant, 1-3 parts of a wetting dispersant, 5-10 parts of a foaming agent, 0.5-1 part of an ultraviolet absorber and 5-12 parts of a vulcanizing agent.

Preferably, the rubber is butadiene rubber, styrene butadiene rubber or natural rubber.

Preferably, the foaming agent is azodicarbonamide and/or diphenyl sulfonyl hydrazide ether.

Preferably, the antioxidant is 1,3, 5-trimethyl-2, 4, 6-tris (3, 5-di-tert-butyl-4-hydroxybenzene) benzene.

Preferably, the ultraviolet light absorber is 2, 4-tert-butyl-6- (5-chlorobenzotriazolyl-2) phenol.

Preferably, the wetting dispersant is BYK-W968 and/or BYK-W985.

Preferably, the vulcanizing agent is one or more of benzoyl peroxide, polysulfide polymer and maleimide derivative.

Preferably, the modified polyurethane is prepared by modifying polyurethane with zirconium-based coordinated methylene diurea; the preparation method of the zirconium-based coordinated methylene diurea comprises the following steps:

s1, weighing methylenedisalicylic acid, adding the methylenedisalicylic acid into absolute ethyl alcohol, stirring the mixture evenly, adding tricarbonyl hydroxyl zirconic acid triammonium, stirring the mixture at room temperature for 24-36 hours under a light-proof condition, and standing the mixture in a refrigerator at 0-4 ℃ for 8-10 hours to obtain a mixed solution A;

wherein the mass ratio of methylene bis-salicylic acid, tricarbonyl hydroxyl zirconic acid triammonium and absolute ethyl alcohol is 1: 2.5-3.2: 12-15;

s2, taking the mixed solution A out of the refrigerator, returning to room temperature, dropwise adding fluozirconic acid, and stirring at room temperature for reaction for 10-12 hours to obtain a mixed solution B;

wherein the mass ratio of the fluozirconic acid to the mixed solution A is 1: 50-80;

s3, adding purified water into the mixed solution B, continuously stirring until the precipitate is not increased any more, filtering to obtain a solid, washing the solid with saturated saline solution three times, then washing the solid with deionized water three times, and drying under reduced pressure to obtain a solid product, namely the zirconium-based coordination methylene diurea;

wherein the mass ratio of the mixed liquid B to the purified water is 1: 2-5.

Preferably, the preparation method of the modified polyurethane comprises the following steps:

s1, dripping polyether polyol into polyisocyanate, mixing uniformly after dripping, and reacting at the temperature of 70-80 ℃ for 4-6 h to obtain a polyurethane prepolymer;

wherein the mass ratio of the polyisocyanate to the polyether polyol is 1:0.85 to 1;

s2, adding methyl ethoxy silicone oil into the polyurethane prepolymer, and stirring and reacting for 1-2 hours at 50-60 ℃ to obtain siloxane polyurethane;

wherein the mass ratio of the polyurethane prepolymer to the methyl ethoxy silicone oil is 1: 0.05-0.2;

s3, adding the zirconium-based coordinated methylene diurea into the siloxane polyurethane, heating to 60-80 ℃, and stirring for reacting for 3-5 hours to obtain modified polyurethane;

wherein the mass ratio of the siloxane polyurethane to the zirconium-based coordinated methylene diurea is 1: 0.1-0.25.

Preferably, the polyisocyanate is one or two mixtures of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate and carbodiimide modified MDI.

Preferably, the polyether polyol is obtained by polyether diol with the molecular weight of 1000-4000 and polyether triol with the molecular weight of 500-2000 according to the mass ratio of 3-5: 1.

Preferably, the flame retardant is a modified halloysite nanotube coated with furfuryl ketone aldehyde resin; the preparation method of the flame retardant comprises the following steps:

s1, weighing phenol, heating to completely melt, adding melamine pyrophosphate, and stirring uniformly in a liquid state to obtain a melamine pyrophosphate solution; weighing halloysite nanotubes, adding the halloysite nanotubes into deionized water, and performing ultrasonic dispersion until the mixture is uniform to obtain a halloysite nanotube solution;

wherein the mass ratio of melamine pyrophosphate to phenol is 1: 5-10; the mass ratio of the halloysite nanotube to the deionized water is 1: 6-8;

s2, heating the melamine pyrophosphate solution to 65-75 ℃, dropwise adding the halloysite nanotube solution, after dropwise adding, continuing to keep the temperature and stir for 0.5-1 h, pouring the solution into a reaction kettle with a polytetrafluoroethylene lining while the solution is hot, reacting for 5-8 h at 100-120 ℃, naturally cooling to room temperature, filtering to obtain a solid, adding the solid into chloroform, stirring for 0.5-1 h, filtering again to obtain the solid, washing with absolute ethyl alcohol for three times, and drying under reduced pressure to obtain a modified halloysite nanotube;

wherein the mass ratio of the melamine pyrophosphate solution to the halloysite nanotube solution is 1: 3-5;

s3, dropwise adding a sodium hydroxide solution into the 2-furaldehyde until the pH value of the liquid is 12.0-13.0, stirring uniformly at 50-60 ℃, dropwise adding acetone, keeping the temperature and stirring for 0.5-1 h, heating to 70-85 ℃, and continuously stirring for 2-3 h to react to obtain a furfuryl ketone aldehyde resin pre-product;

wherein the mass ratio of the 2-furaldehyde to the acetone is 1: 1.5-3;

s4, weighing the modified halloysite nanotube, adding the modified halloysite nanotube into the furfuryl ketone aldehyde resin pre-product, stirring the mixture uniformly, then dropwise adding a sulfuric acid solution until the pH value of the liquid is 2.0-3.0, then adding formaldehyde with the mass fraction of 36-38%, boiling the mixture, performing condensation reflux reaction for 3-5 hours, cooling the mixture to room temperature, then dropwise adding a sodium hydroxide solution until the pH value of the solution is neutral, washing the solution with deionized water for three times, then washing the solution with absolute ethyl alcohol for three times, performing rotary evaporation to remove a solvent, and then placing the solution in a drying oven for treatment at 70-80 ℃ for 3-8 hours to obtain a modified halloysite nanotube coated with furfuryl ketone aldehyde resin;

wherein the mass ratio of the modified halloysite nanotube to the furfuryl ketone aldehyde resin pre-product to formaldehyde is 1: 6-8: 0.5-2.

Another object of the present invention is to provide a method for preparing a composite anti-condensation polyurethane sealing member, comprising the steps of:

step 1, plastication treatment: adding the weighed modified polyurethane and rubber into a plasticator for plastication treatment to obtain a plasticated treatment substance;

step 2, mixing treatment: adding the plasticated material obtained in the step 1 into a mixing roll for mixing treatment, then sequentially adding a flame retardant, an antioxidant, a wetting dispersant and an ultraviolet absorbent which are weighed according to the amount, stirring the mixture to be uniform after adding each raw material, and obtaining the mixed material after completely adding the raw materials;

step 3, foaming treatment: then mixing the mixing processed object in the step 2 with a foaming agent weighed according to the amount, placing the mixture into a foaming mold, sequentially carrying out mold closing, air exhausting and curing treatment, and then demolding to obtain a foaming processed object;

and 4, vulcanizing treatment: and (4) adding a vulcanizing agent weighed according to the amount into the foaming treatment object obtained in the step (3), and obtaining the composite anti-condensation polyurethane sealing element after the vulcanization treatment is finished.

The invention has the beneficial effects that:

1. the composite anti-condensation polyurethane sealing element prepared by the invention not only has the advantages of good elasticity, good low-temperature flexibility, wear resistance, good cohesiveness and good mechanical strength of polyurethane, but also overcomes the defect of poor heat resistance of polyurethane, and greatly improves the condensation resistance and flame retardant property.

2. Condensation is a phenomenon in which water vapor condenses on a relatively low-temperature object when the water vapor reaches a saturation level in the air. The outer tubes and other connecting wires of a plurality of existing devices are made of polyurethane materials, condensation often appears on the surfaces of the devices when the humidity is high in the morning in autumn, and although polyurethane has certain water resistance, the moisture in the air is easily absorbed. Thus, over the long term, moisture gradually decomposes the ester groups in the polyurethane, thereby shortening the useful life of the equipment.

3. The method comprises the steps of carrying out mixing pre-reaction on methylene bis-salicylic acid and tricarbonyl hydroxyl zirconic acid triammonium, wherein carboxyl on benzene rings on two sides in methylene bis-salicylic acid molecules and hydroxyl in tricarbonyl hydroxyl zirconic acid triammonium molecules are subjected to condensation reaction, then adding fluozirconic acid, and further carrying out catalytic reaction to form metal zirconium coordination and annular zirconium-based coordination methylene diurea. The zirconium-based coordinated methylene diurea prepared by the invention is modified in the preparation process of polyurethane, and specifically comprises the following steps: the polyurethane prepolymer obtained by reacting polyisocyanate with polyether polyol is firstly modified by methyl ethoxy silicone oil to obtain siloxane polyurethane, and then zirconium-based coordinated methylene diurea is added for grafting modification. According to the invention, the organic siloxane end-capped grafted polyurethane prepolymer is adopted, so that the polyurethane has the advantage of aging resistance of organic silicon while the advantages of the polyurethane are kept, the later added zirconium-based coordinated methylene diurea can be combined with the polyurethane prepolymer more tightly, residual isocyanate groups in the prepolymer can be removed by urea groups contained in the zirconium-based coordinated methylene diurea, the effect is better than that of amino groups, the viscosity is more stable, and the finally obtained modified polyurethane is greatly improved in water resistance and acid and alkali resistance.

4. The invention also prepares the flame retardant with excellent flame retardant effect, which specifically comprises the following components: firstly, modifying a halloysite nanotube by melamine pyrophosphate to obtain a modified halloysite nanotube; reacting 2-furfural with acetone to obtain a furfuryl ketone aldehyde resin pre-product; and then, continuously reacting the modified halloysite nanotube with the furfuralacetonaldehyde resin pre-product to obtain a furfuralacetonaldehyde resin-coated modified halloysite nanotube, wherein the furfuralacetonaldehyde resin-coated modified halloysite nanotube can be used for modifying the flame retardant property of polyurethane and reducing the hysteresis loss of polyurethane materials to a greater extent.

Detailed Description

The invention is further described with reference to the following examples.

Example 1

The composite anti-condensation polyurethane sealing element comprises the following components in parts by weight:

65 parts of modified polyurethane, 20 parts of rubber, 3 parts of flame retardant, 1 part of antioxidant, 2 parts of wetting dispersant, 8 parts of foaming agent, 0.75 part of ultraviolet absorbent and 8 parts of vulcanizing agent.

The rubber is butadiene rubber.

The foaming agent is azodicarbonamide.

The antioxidant is 1,3, 5-trimethyl-2, 4, 6-tri (3, 5-di-tert-butyl-4-hydroxybenzene) benzene.

The ultraviolet absorbent is 2, 4-tert-butyl-6- (5-chlorobenzotriazolyl-2) phenol.

The wetting dispersant is BYK-W968.

The vulcanizing agent is benzoyl peroxide.

The modified polyurethane is prepared by modifying polyurethane through zirconium-based coordinated methylene diurea; the preparation method of the zirconium-based coordinated methylene diurea comprises the following steps:

s1, weighing methylenedisalicylic acid, adding the methylenedisalicylic acid into absolute ethyl alcohol, stirring the mixture evenly, adding tricarbonyl hydroxyl zirconic acid triammonium, stirring the mixture at room temperature for 24-36 hours under a light-proof condition, and standing the mixture in a refrigerator at 0-4 ℃ for 8-10 hours to obtain a mixed solution A;

wherein the mass ratio of methylene bis-salicylic acid, tricarbonyl hydroxyl zirconic acid triammonium and absolute ethyl alcohol is 1: 2.5-3.2: 12-15;

s2, taking the mixed solution A out of the refrigerator, returning to room temperature, dropwise adding fluozirconic acid, and stirring at room temperature for reaction for 10-12 hours to obtain a mixed solution B;

wherein the mass ratio of the fluozirconic acid to the mixed solution A is 1: 50-80;

s3, adding purified water into the mixed solution B, continuously stirring until the precipitate is not increased any more, filtering to obtain a solid, washing the solid with saturated saline solution three times, then washing the solid with deionized water three times, and drying under reduced pressure to obtain a solid product, namely the zirconium-based coordination methylene diurea;

wherein the mass ratio of the mixed liquid B to the purified water is 1: 2-5.

The preparation method of the modified polyurethane comprises the following steps:

s1, dripping polyether polyol into polyisocyanate, mixing uniformly after dripping, and reacting at the temperature of 70-80 ℃ for 4-6 h to obtain a polyurethane prepolymer;

wherein the mass ratio of the polyisocyanate to the polyether polyol is 1:0.85 to 1;

s2, adding methyl ethoxy silicone oil into the polyurethane prepolymer, and stirring and reacting for 1-2 hours at 50-60 ℃ to obtain siloxane polyurethane;

wherein the mass ratio of the polyurethane prepolymer to the methyl ethoxy silicone oil is 1: 0.05-0.2;

s3, adding the zirconium-based coordinated methylene diurea into the siloxane polyurethane, heating to 60-80 ℃, and stirring for reacting for 3-5 hours to obtain modified polyurethane;

wherein the mass ratio of the siloxane polyurethane to the zirconium-based coordinated methylene diurea is 1: 0.1-0.25.

The polyisocyanate is one or a mixture of two of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate and carbodiimide modified MDI.

The polyether polyol is obtained by polyether diol with the molecular weight of 1000-4000 and polyether triol with the molecular weight of 500-2000 according to the mass ratio of 3-5: 1.

The flame retardant is a modified halloysite nanotube coated by furfuryl ketone aldehyde resin; the preparation method of the flame retardant comprises the following steps:

s1, weighing phenol, heating to completely melt, adding melamine pyrophosphate, and stirring uniformly in a liquid state to obtain a melamine pyrophosphate solution; weighing halloysite nanotubes, adding the halloysite nanotubes into deionized water, and performing ultrasonic dispersion until the mixture is uniform to obtain a halloysite nanotube solution;

wherein the mass ratio of melamine pyrophosphate to phenol is 1: 5-10; the mass ratio of the halloysite nanotube to the deionized water is 1: 6-8;

s2, heating the melamine pyrophosphate solution to 65-75 ℃, dropwise adding the halloysite nanotube solution, after dropwise adding, continuing to keep the temperature and stir for 0.5-1 h, pouring the solution into a reaction kettle with a polytetrafluoroethylene lining while the solution is hot, reacting for 5-8 h at 100-120 ℃, naturally cooling to room temperature, filtering to obtain a solid, adding the solid into chloroform, stirring for 0.5-1 h, filtering again to obtain the solid, washing with absolute ethyl alcohol for three times, and drying under reduced pressure to obtain a modified halloysite nanotube;

wherein the mass ratio of the melamine pyrophosphate solution to the halloysite nanotube solution is 1: 3-5;

s3, dropwise adding a sodium hydroxide solution into the 2-furaldehyde until the pH value of the liquid is 12.0-13.0, stirring uniformly at 50-60 ℃, dropwise adding acetone, keeping the temperature and stirring for 0.5-1 h, heating to 70-85 ℃, and continuously stirring for 2-3 h to react to obtain a furfuryl ketone aldehyde resin pre-product;

wherein the mass ratio of the 2-furaldehyde to the acetone is 1: 1.5-3;

s4, weighing the modified halloysite nanotube, adding the modified halloysite nanotube into the furfuryl ketone aldehyde resin pre-product, stirring the mixture uniformly, then dropwise adding a sulfuric acid solution until the pH value of the liquid is 2.0-3.0, then adding formaldehyde with the mass fraction of 36-38%, boiling the mixture, performing condensation reflux reaction for 3-5 hours, cooling the mixture to room temperature, then dropwise adding a sodium hydroxide solution until the pH value of the solution is neutral, washing the solution with deionized water for three times, then washing the solution with absolute ethyl alcohol for three times, performing rotary evaporation to remove a solvent, and then placing the solution in a drying oven for treatment at 70-80 ℃ for 3-8 hours to obtain a modified halloysite nanotube coated with furfuryl ketone aldehyde resin;

wherein the mass ratio of the modified halloysite nanotube to the furfuryl ketone aldehyde resin pre-product to formaldehyde is 1: 6-8: 0.5-2.

The preparation method of the composite anti-condensation polyurethane sealing element comprises the following steps:

step 1, plastication treatment: adding the weighed modified polyurethane and rubber into a plasticator for plastication treatment to obtain a plasticated treatment substance;

step 2, mixing treatment: adding the plasticated material obtained in the step 1 into a mixing roll for mixing treatment, then sequentially adding a flame retardant, an antioxidant, a wetting dispersant and an ultraviolet absorbent which are weighed according to the amount, stirring the mixture to be uniform after adding each raw material, and obtaining the mixed material after completely adding the raw materials;

step 3, foaming treatment: then mixing the mixing processed object in the step 2 with a foaming agent weighed according to the amount, placing the mixture into a foaming mold, sequentially carrying out mold closing, air exhausting and curing treatment, and then demolding to obtain a foaming processed object;

and 4, vulcanizing treatment: and (4) adding a vulcanizing agent weighed according to the amount into the foaming treatment object obtained in the step (3), and obtaining the composite anti-condensation polyurethane sealing element after the vulcanization treatment is finished.

Example 2

The composite anti-condensation polyurethane sealing element comprises the following components in parts by weight:

50 parts of modified polyurethane, 10 parts of rubber, 2 parts of flame retardant, 0.5 part of antioxidant, 1 part of wetting dispersant, 5 parts of foaming agent, 0.5 part of ultraviolet absorbent and 5 parts of vulcanizing agent.

The rubber is styrene butadiene rubber.

The foaming agent is diphenyl sulfonyl hydrazide ether.

The antioxidant is 1,3, 5-trimethyl-2, 4, 6-tri (3, 5-di-tert-butyl-4-hydroxybenzene) benzene.

The ultraviolet absorbent is 2, 4-tert-butyl-6- (5-chlorobenzotriazolyl-2) phenol.

The wetting dispersant is BYK-W985.

The vulcanizing agent is a polysulfide polymer.

The modified polyurethane is prepared by modifying polyurethane through zirconium-based coordinated methylene diurea; the preparation method of the zirconium-based coordinated methylene diurea comprises the following steps:

s1, weighing methylenedisalicylic acid, adding the methylenedisalicylic acid into absolute ethyl alcohol, stirring the mixture evenly, adding tricarbonyl hydroxyl zirconic acid triammonium, stirring the mixture at room temperature for 24-36 hours under a light-proof condition, and standing the mixture in a refrigerator at 0-4 ℃ for 8-10 hours to obtain a mixed solution A;

wherein the mass ratio of methylene bis-salicylic acid, tricarbonyl hydroxyl zirconic acid triammonium and absolute ethyl alcohol is 1: 2.5-3.2: 12-15;

s2, taking the mixed solution A out of the refrigerator, returning to room temperature, dropwise adding fluozirconic acid, and stirring at room temperature for reaction for 10-12 hours to obtain a mixed solution B;

wherein the mass ratio of the fluozirconic acid to the mixed solution A is 1: 50-80;

s3, adding purified water into the mixed solution B, continuously stirring until the precipitate is not increased any more, filtering to obtain a solid, washing the solid with saturated saline solution three times, then washing the solid with deionized water three times, and drying under reduced pressure to obtain a solid product, namely the zirconium-based coordination methylene diurea;

wherein the mass ratio of the mixed liquid B to the purified water is 1: 2-5.

The preparation method of the modified polyurethane comprises the following steps:

s1, dripping polyether polyol into polyisocyanate, mixing uniformly after dripping, and reacting at the temperature of 70-80 ℃ for 4-6 h to obtain a polyurethane prepolymer;

wherein the mass ratio of the polyisocyanate to the polyether polyol is 1:0.85 to 1;

s2, adding methyl ethoxy silicone oil into the polyurethane prepolymer, and stirring and reacting for 1-2 hours at 50-60 ℃ to obtain siloxane polyurethane;

wherein the mass ratio of the polyurethane prepolymer to the methyl ethoxy silicone oil is 1: 0.05-0.2;

s3, adding the zirconium-based coordinated methylene diurea into the siloxane polyurethane, heating to 60-80 ℃, and stirring for reacting for 3-5 hours to obtain modified polyurethane;

wherein the mass ratio of the siloxane polyurethane to the zirconium-based coordinated methylene diurea is 1: 0.1-0.25.

The polyisocyanate is one or a mixture of two of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate and carbodiimide modified MDI.

The polyether polyol is obtained by polyether diol with the molecular weight of 1000-4000 and polyether triol with the molecular weight of 500-2000 according to the mass ratio of 3-5: 1.

The flame retardant is a modified halloysite nanotube coated by furfuryl ketone aldehyde resin; the preparation method of the flame retardant comprises the following steps:

s1, weighing phenol, heating to completely melt, adding melamine pyrophosphate, and stirring uniformly in a liquid state to obtain a melamine pyrophosphate solution; weighing halloysite nanotubes, adding the halloysite nanotubes into deionized water, and performing ultrasonic dispersion until the mixture is uniform to obtain a halloysite nanotube solution;

wherein the mass ratio of melamine pyrophosphate to phenol is 1: 5-10; the mass ratio of the halloysite nanotube to the deionized water is 1: 6-8;

s2, heating the melamine pyrophosphate solution to 65-75 ℃, dropwise adding the halloysite nanotube solution, after dropwise adding, continuing to keep the temperature and stir for 0.5-1 h, pouring the solution into a reaction kettle with a polytetrafluoroethylene lining while the solution is hot, reacting for 5-8 h at 100-120 ℃, naturally cooling to room temperature, filtering to obtain a solid, adding the solid into chloroform, stirring for 0.5-1 h, filtering again to obtain the solid, washing with absolute ethyl alcohol for three times, and drying under reduced pressure to obtain a modified halloysite nanotube;

wherein the mass ratio of the melamine pyrophosphate solution to the halloysite nanotube solution is 1: 3-5;

s3, dropwise adding a sodium hydroxide solution into the 2-furaldehyde until the pH value of the liquid is 12.0-13.0, stirring uniformly at 50-60 ℃, dropwise adding acetone, keeping the temperature and stirring for 0.5-1 h, heating to 70-85 ℃, and continuously stirring for 2-3 h to react to obtain a furfuryl ketone aldehyde resin pre-product;

wherein the mass ratio of the 2-furaldehyde to the acetone is 1: 1.5-3;

s4, weighing the modified halloysite nanotube, adding the modified halloysite nanotube into the furfuryl ketone aldehyde resin pre-product, stirring the mixture uniformly, then dropwise adding a sulfuric acid solution until the pH value of the liquid is 2.0-3.0, then adding formaldehyde with the mass fraction of 36-38%, boiling the mixture, performing condensation reflux reaction for 3-5 hours, cooling the mixture to room temperature, then dropwise adding a sodium hydroxide solution until the pH value of the solution is neutral, washing the solution with deionized water for three times, then washing the solution with absolute ethyl alcohol for three times, performing rotary evaporation to remove a solvent, and then placing the solution in a drying oven for treatment at 70-80 ℃ for 3-8 hours to obtain a modified halloysite nanotube coated with furfuryl ketone aldehyde resin;

wherein the mass ratio of the modified halloysite nanotube to the furfuryl ketone aldehyde resin pre-product to formaldehyde is 1: 6-8: 0.5-2.

The preparation method of the composite anti-condensation polyurethane sealing element comprises the following steps:

step 1, plastication treatment: adding the weighed modified polyurethane and rubber into a plasticator for plastication treatment to obtain a plasticated treatment substance;

step 2, mixing treatment: adding the plasticated material obtained in the step 1 into a mixing roll for mixing treatment, then sequentially adding a flame retardant, an antioxidant, a wetting dispersant and an ultraviolet absorbent which are weighed according to the amount, stirring the mixture to be uniform after adding each raw material, and obtaining the mixed material after completely adding the raw materials;

step 3, foaming treatment: then mixing the mixing processed object in the step 2 with a foaming agent weighed according to the amount, placing the mixture into a foaming mold, sequentially carrying out mold closing, air exhausting and curing treatment, and then demolding to obtain a foaming processed object;

and 4, vulcanizing treatment: and (4) adding a vulcanizing agent weighed according to the amount into the foaming treatment object obtained in the step (3), and obtaining the composite anti-condensation polyurethane sealing element after the vulcanization treatment is finished.

Example 3

The composite anti-condensation polyurethane sealing element comprises the following components in parts by weight:

80 parts of modified polyurethane, 30 parts of rubber, 5 parts of flame retardant, 2 parts of antioxidant, 3 parts of wetting dispersant, 10 parts of foaming agent, 1 part of ultraviolet absorbent and 12 parts of vulcanizing agent.

The rubber is natural rubber.

The foaming agent is diphenyl sulfonyl hydrazide ether.

The antioxidant is 1,3, 5-trimethyl-2, 4, 6-tri (3, 5-di-tert-butyl-4-hydroxybenzene) benzene.

The ultraviolet absorbent is 2, 4-tert-butyl-6- (5-chlorobenzotriazolyl-2) phenol.

The wetting dispersant is BYK-W968.

The vulcanizing agent is a maleimide derivative.

The modified polyurethane is prepared by modifying polyurethane through zirconium-based coordinated methylene diurea; the preparation method of the zirconium-based coordinated methylene diurea comprises the following steps:

s1, weighing methylenedisalicylic acid, adding the methylenedisalicylic acid into absolute ethyl alcohol, stirring the mixture evenly, adding tricarbonyl hydroxyl zirconic acid triammonium, stirring the mixture at room temperature for 24-36 hours under a light-proof condition, and standing the mixture in a refrigerator at 0-4 ℃ for 8-10 hours to obtain a mixed solution A;

wherein the mass ratio of methylene bis-salicylic acid, tricarbonyl hydroxyl zirconic acid triammonium and absolute ethyl alcohol is 1: 2.5-3.2: 12-15;

s2, taking the mixed solution A out of the refrigerator, returning to room temperature, dropwise adding fluozirconic acid, and stirring at room temperature for reaction for 10-12 hours to obtain a mixed solution B;

wherein the mass ratio of the fluozirconic acid to the mixed solution A is 1: 50-80;

s3, adding purified water into the mixed solution B, continuously stirring until the precipitate is not increased any more, filtering to obtain a solid, washing the solid with saturated saline solution three times, then washing the solid with deionized water three times, and drying under reduced pressure to obtain a solid product, namely the zirconium-based coordination methylene diurea;

wherein the mass ratio of the mixed liquid B to the purified water is 1: 2-5.

The preparation method of the modified polyurethane comprises the following steps:

s1, dripping polyether polyol into polyisocyanate, mixing uniformly after dripping, and reacting at the temperature of 70-80 ℃ for 4-6 h to obtain a polyurethane prepolymer;

wherein the mass ratio of the polyisocyanate to the polyether polyol is 1:0.85 to 1;

s2, adding methyl ethoxy silicone oil into the polyurethane prepolymer, and stirring and reacting for 1-2 hours at 50-60 ℃ to obtain siloxane polyurethane;

wherein the mass ratio of the polyurethane prepolymer to the methyl ethoxy silicone oil is 1: 0.05-0.2;

s3, adding the zirconium-based coordinated methylene diurea into the siloxane polyurethane, heating to 60-80 ℃, and stirring for reacting for 3-5 hours to obtain modified polyurethane;

wherein the mass ratio of the siloxane polyurethane to the zirconium-based coordinated methylene diurea is 1: 0.1-0.25.

The polyisocyanate is one or a mixture of two of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate and carbodiimide modified MDI.

The polyether polyol is obtained by polyether diol with the molecular weight of 1000-4000 and polyether triol with the molecular weight of 500-2000 according to the mass ratio of 3-5: 1.

The flame retardant is a modified halloysite nanotube coated by furfuryl ketone aldehyde resin; the preparation method of the flame retardant comprises the following steps:

s1, weighing phenol, heating to completely melt, adding melamine pyrophosphate, and stirring uniformly in a liquid state to obtain a melamine pyrophosphate solution; weighing halloysite nanotubes, adding the halloysite nanotubes into deionized water, and performing ultrasonic dispersion until the mixture is uniform to obtain a halloysite nanotube solution;

wherein the mass ratio of melamine pyrophosphate to phenol is 1: 5-10; the mass ratio of the halloysite nanotube to the deionized water is 1: 6-8;

s2, heating the melamine pyrophosphate solution to 65-75 ℃, dropwise adding the halloysite nanotube solution, after dropwise adding, continuing to keep the temperature and stir for 0.5-1 h, pouring the solution into a reaction kettle with a polytetrafluoroethylene lining while the solution is hot, reacting for 5-8 h at 100-120 ℃, naturally cooling to room temperature, filtering to obtain a solid, adding the solid into chloroform, stirring for 0.5-1 h, filtering again to obtain the solid, washing with absolute ethyl alcohol for three times, and drying under reduced pressure to obtain a modified halloysite nanotube;

wherein the mass ratio of the melamine pyrophosphate solution to the halloysite nanotube solution is 1: 3-5;

s3, dropwise adding a sodium hydroxide solution into the 2-furaldehyde until the pH value of the liquid is 12.0-13.0, stirring uniformly at 50-60 ℃, dropwise adding acetone, keeping the temperature and stirring for 0.5-1 h, heating to 70-85 ℃, and continuously stirring for 2-3 h to react to obtain a furfuryl ketone aldehyde resin pre-product;

wherein the mass ratio of the 2-furaldehyde to the acetone is 1: 1.5-3;

s4, weighing the modified halloysite nanotube, adding the modified halloysite nanotube into the furfuryl ketone aldehyde resin pre-product, stirring the mixture uniformly, then dropwise adding a sulfuric acid solution until the pH value of the liquid is 2.0-3.0, then adding formaldehyde with the mass fraction of 36-38%, boiling the mixture, performing condensation reflux reaction for 3-5 hours, cooling the mixture to room temperature, then dropwise adding a sodium hydroxide solution until the pH value of the solution is neutral, washing the solution with deionized water for three times, then washing the solution with absolute ethyl alcohol for three times, performing rotary evaporation to remove a solvent, and then placing the solution in a drying oven for treatment at 70-80 ℃ for 3-8 hours to obtain a modified halloysite nanotube coated with furfuryl ketone aldehyde resin;

wherein the mass ratio of the modified halloysite nanotube to the furfuryl ketone aldehyde resin pre-product to formaldehyde is 1: 6-8: 0.5-2.

The preparation method of the composite anti-condensation polyurethane sealing element comprises the following steps:

step 1, plastication treatment: adding the weighed modified polyurethane and rubber into a plasticator for plastication treatment to obtain a plasticated treatment substance;

step 2, mixing treatment: adding the plasticated material obtained in the step 1 into a mixing roll for mixing treatment, then sequentially adding a flame retardant, an antioxidant, a wetting dispersant and an ultraviolet absorbent which are weighed according to the amount, stirring the mixture to be uniform after adding each raw material, and obtaining the mixed material after completely adding the raw materials;

step 3, foaming treatment: then mixing the mixing processed object in the step 2 with a foaming agent weighed according to the amount, placing the mixture into a foaming mold, sequentially carrying out mold closing, air exhausting and curing treatment, and then demolding to obtain a foaming processed object;

and 4, vulcanizing treatment: and (4) adding a vulcanizing agent weighed according to the amount into the foaming treatment object obtained in the step (3), and obtaining the composite anti-condensation polyurethane sealing element after the vulcanization treatment is finished.

Comparative example

The composite anti-condensation polyurethane sealing element comprises the following components in parts by weight:

65 parts of polyurethane, 20 parts of rubber, 3 parts of flame retardant, 1 part of antioxidant, 2 parts of wetting dispersant, 8 parts of foaming agent, 0.75 part of ultraviolet absorber and 8 parts of vulcanizing agent.

The rubber is butadiene rubber.

The foaming agent is azodicarbonamide.

The antioxidant is 1,3, 5-trimethyl-2, 4, 6-tri (3, 5-di-tert-butyl-4-hydroxybenzene) benzene.

The ultraviolet absorbent is 2, 4-tert-butyl-6- (5-chlorobenzotriazolyl-2) phenol.

The wetting dispersant is BYK-W968.

The vulcanizing agent is benzoyl peroxide.

The flame retardant is a halloysite nanotube.

The preparation method of the composite anti-condensation polyurethane sealing element comprises the following steps:

step 1, plastication treatment: adding the polyurethane and the rubber which are weighed according to the amount into a plasticator for plastication treatment to obtain a plasticated treatment object;

step 2, mixing treatment: adding the plasticated material obtained in the step 1 into a mixing roll for mixing treatment, then sequentially adding a flame retardant, an antioxidant, a wetting dispersant and an ultraviolet absorbent which are weighed according to the amount, stirring the mixture to be uniform after adding each raw material, and obtaining the mixed material after completely adding the raw materials;

step 3, foaming treatment: then mixing the mixing processed object in the step 2 with a foaming agent weighed according to the amount, placing the mixture into a foaming mold, sequentially carrying out mold closing, air exhausting and curing treatment, and then demolding to obtain a foaming processed object;

and 4, vulcanizing treatment: and (4) adding a vulcanizing agent weighed according to the amount into the foaming treatment object obtained in the step (3), and obtaining the composite anti-condensation polyurethane sealing element after the vulcanization treatment is finished.

For a clearer illustration of the invention, the performance of the composite anti-condensation polyurethane sealing element prepared in the invention examples 1-3 and the comparative example is tested and compared, wherein the tensile strength is tested according to the standard GB/T528-1998; the Shore A hardness is tested according to the standard GB/T531-1992; the compressive strength is detected according to the standard GB/T8813-; hydrolysis resistance (i.e. compressive strength retention) is measured according to the standard GB/T20875.2-2010, oxygen index is measured according to the standard GB/T2406-1993, and hysteresis loss rate is measured according to the standard GB/T33609-2017.

The results are shown in Table 1.

Table 1 performance of different composite anti-condensation polyurethane seals

	Example 1	Example 2	Example 3	Comparative example
					Hardness 25 deg.C (Shao A)	97	94	95	81
Tensile Strength (MPa)	75	72	78	66
					High temperature resistance (DEG C)	＞180	＞180	＞180	＜120
Water contact Angle (°)	128	121	123	72
					Compressive strength (MPa)	1.05	1.03	1.03	0.84
Hydrolysis resistance (%)	98.5	98.2	98.6	76.3
					Oxygen index	32.6	31.3	32.7	19.4
Hysteresis loss Rate (%)	11.2	13.4	12.0	22.6

As can be seen from table 1, the polyurethane sealing members prepared in embodiments 1 to 3 of the present invention have the advantages of excellent high temperature resistance, hydrophobicity (anti-condensation), hydrolysis resistance, high flame retardancy, and low hysteresis loss.

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 (10)

1. The composite anti-condensation polyurethane sealing element is characterized by comprising the following components in parts by weight:

50-80 parts of modified polyurethane, 10-30 parts of rubber, 2-5 parts of a flame retardant, 0.5-2 parts of an antioxidant, 1-3 parts of a wetting dispersant, 5-10 parts of a foaming agent, 0.5-1 part of an ultraviolet absorber and 5-12 parts of a vulcanizing agent.

2. A composite condensation resistant polyurethane seal according to claim 1 wherein said rubber is butadiene rubber, styrene butadiene rubber or natural rubber.

3. A composite condensation resistant polyurethane seal according to claim 1 wherein said blowing agent is azodicarbonamide and/or diphenylsulfonylhydrazide ether.

4. The composite condensation resistant polyurethane seal of claim 1, wherein said antioxidant is 1,3, 5-trimethyl-2, 4, 6-tris (3, 5-di-tert-butyl-4-hydroxyphenyl) benzene; the ultraviolet absorbent is 2, 4-tert-butyl-6- (5-chlorobenzotriazolyl-2) phenol.

5. A composite anti-condensation polyurethane seal according to claim 1, wherein said wetting and dispersing agent is BYK-W968 and/or BYK-W985.

6. A composite anti-condensation polyurethane seal according to claim 1, wherein the vulcanizing agent is one or more of benzoyl peroxide, polysulfide polymer, maleimide derivative.

7. The composite condensation-resistant polyurethane sealing element according to claim 1, wherein the modified polyurethane is prepared by modifying polyurethane with zirconium-based coordinated methylene diurea; the preparation method of the zirconium-based coordinated methylene diurea comprises the following steps:

s1, weighing methylenedisalicylic acid, adding the methylenedisalicylic acid into absolute ethyl alcohol, stirring the mixture evenly, adding tricarbonyl hydroxyl zirconic acid triammonium, stirring the mixture at room temperature for 24-36 hours under a light-proof condition, and standing the mixture in a refrigerator at 0-4 ℃ for 8-10 hours to obtain a mixed solution A;

wherein the mass ratio of methylene bis-salicylic acid, tricarbonyl hydroxyl zirconic acid triammonium and absolute ethyl alcohol is 1: 2.5-3.2: 12-15;

s2, taking the mixed solution A out of the refrigerator, returning to room temperature, dropwise adding fluozirconic acid, and stirring at room temperature for reaction for 10-12 hours to obtain a mixed solution B;

wherein the mass ratio of the fluozirconic acid to the mixed solution A is 1: 50-80;

s3, adding purified water into the mixed solution B, continuously stirring until the precipitate is not increased any more, filtering to obtain a solid, washing the solid with saturated saline solution three times, then washing the solid with deionized water three times, and drying under reduced pressure to obtain a solid product, namely the zirconium-based coordination methylene diurea;

wherein the mass ratio of the mixed liquid B to the purified water is 1: 2-5.

8. The composite anti-condensation polyurethane sealing element according to claim 1, wherein the preparation method of the modified polyurethane comprises the following steps:

s1, dripping polyether polyol into polyisocyanate, mixing uniformly after dripping, and reacting at the temperature of 70-80 ℃ for 4-6 h to obtain a polyurethane prepolymer;

wherein the mass ratio of the polyisocyanate to the polyether polyol is 1: 0.85-1;

s2, adding methyl ethoxy silicone oil into the polyurethane prepolymer, and stirring and reacting for 1-2 hours at 50-60 ℃ to obtain siloxane polyurethane;

wherein the mass ratio of the polyurethane prepolymer to the methyl ethoxy silicone oil is 1: 0.05-0.2;

s3, adding the zirconium-based coordinated methylene diurea into the siloxane polyurethane, heating to 60-80 ℃, and stirring for reacting for 3-5 hours to obtain modified polyurethane;

wherein the mass ratio of the siloxane polyurethane to the zirconium-based coordinated methylene diurea is 1: 0.1-0.25.

9. A composite condensation resistant polyurethane seal according to claim 1 wherein said flame retardant is furfuryl ketone aldehyde resin coated modified halloysite nanotubes; the preparation method of the flame retardant comprises the following steps:

s1, weighing phenol, heating to completely melt, adding melamine pyrophosphate, and stirring uniformly in a liquid state to obtain a melamine pyrophosphate solution; weighing halloysite nanotubes, adding the halloysite nanotubes into deionized water, and performing ultrasonic dispersion until the mixture is uniform to obtain a halloysite nanotube solution;

wherein the mass ratio of melamine pyrophosphate to phenol is 1: 5-10; the mass ratio of the halloysite nanotube to the deionized water is 1: 6-8;

s2, heating the melamine pyrophosphate solution to 65-75 ℃, dropwise adding the halloysite nanotube solution, after dropwise adding, continuing to keep the temperature and stir for 0.5-1 h, pouring the solution into a reaction kettle with a polytetrafluoroethylene lining while the solution is hot, reacting for 5-8 h at 100-120 ℃, naturally cooling to room temperature, filtering to obtain a solid, adding the solid into chloroform, stirring for 0.5-1 h, filtering again to obtain the solid, washing with absolute ethyl alcohol for three times, and drying under reduced pressure to obtain a modified halloysite nanotube;

wherein the mass ratio of the melamine pyrophosphate solution to the halloysite nanotube solution is 1: 3-5;

s3, dropwise adding a sodium hydroxide solution into the 2-furaldehyde until the pH value of the liquid is 12.0-13.0, stirring uniformly at 50-60 ℃, dropwise adding acetone, keeping the temperature and stirring for 0.5-1 h, heating to 70-85 ℃, and continuously stirring for 2-3 h to react to obtain a furfuryl ketone aldehyde resin pre-product;

wherein the mass ratio of the 2-furaldehyde to the acetone is 1: 1.5-3;

s4, weighing the modified halloysite nanotube, adding the modified halloysite nanotube into the furfuryl ketone aldehyde resin pre-product, stirring the mixture uniformly, then dropwise adding a sulfuric acid solution until the pH value of the liquid is 2.0-3.0, then adding formaldehyde with the mass fraction of 36-38%, boiling the mixture, performing condensation reflux reaction for 3-5 hours, cooling the mixture to room temperature, then dropwise adding a sodium hydroxide solution until the pH value of the solution is neutral, washing the solution with deionized water for three times, then washing the solution with absolute ethyl alcohol for three times, performing rotary evaporation to remove a solvent, and then placing the solution in a drying oven for treatment at 70-80 ℃ for 3-8 hours to obtain a modified halloysite nanotube coated with furfuryl ketone aldehyde resin;

wherein the mass ratio of the modified halloysite nanotube to the furfuryl ketone aldehyde resin pre-product to formaldehyde is 1: 6-8: 0.5-2.

10. A method for preparing the composite anti-condensation polyurethane sealing element according to any one of claims 1 to 9, wherein the method comprises the following steps:

step 1, plastication treatment: adding the weighed modified polyurethane and rubber into a plasticator for plastication treatment to obtain a plasticated treatment substance;

step 2, mixing treatment: adding the plasticated material obtained in the step 1 into a mixing roll for mixing treatment, then sequentially adding a flame retardant, an antioxidant, a wetting dispersant and an ultraviolet absorbent which are weighed according to the amount, stirring the mixture to be uniform after adding each raw material, and obtaining the mixed material after completely adding the raw materials;

step 3, foaming treatment: then mixing the mixing processed object in the step 2 with a foaming agent weighed according to the amount, placing the mixture into a foaming mold, sequentially carrying out mold closing, air exhausting and curing treatment, and then demolding to obtain a foaming processed object;

and 4, vulcanizing treatment: and (4) adding a vulcanizing agent weighed according to the amount into the foaming treatment object obtained in the step (3), and obtaining the composite anti-condensation polyurethane sealing element after the vulcanization treatment is finished.