CN112574383B - Waterborne polyurethane emulsion and preparation method and application thereof - Google Patents

Waterborne polyurethane emulsion and preparation method and application thereof Download PDF

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CN112574383B
CN112574383B CN202011466543.4A CN202011466543A CN112574383B CN 112574383 B CN112574383 B CN 112574383B CN 202011466543 A CN202011466543 A CN 202011466543A CN 112574383 B CN112574383 B CN 112574383B
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polyurethane emulsion
emulsion
oligomer
aqueous polyurethane
chain extender
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CN112574383A (en
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杜明兵
赵鸿凯
孙向浩
张其斌
杨银龙
钱程
刘宇航
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Shanghai Huafeng Super Fiber Technology Co ltd
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Shanghai Huafeng Super Fiber Technology Co ltd
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    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
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Abstract

The invention relates to a waterborne polyurethane emulsion and a preparation method and application thereof, wherein crosslinkable waterborne polyurethane emulsion and a vulcanizing agent are subjected to vulcanization reaction and then are subjected to centrifugal treatment to obtain a crosslinking waterborne polyurethane emulsion; the waterborne polyurethane emulsion comprises crosslinked waterborne polyurethane, wherein the molecular chain of the crosslinked waterborne polyurethane contains 0.5-2 wt% of chain segment A and 99.5-98 wt% of chain segment B; the chain segment A is connected with the chain segment B by carbamate, and the chain segment A is composed of structural units containing carbon-carbon double bonds and hydrophilic group sulfonic groups; the chain segment A is obtained by reacting monohydric alcohol containing double bond sulfonic group with diisocyanate, and the chain segment B is a polyurethane chain segment containing ether bond; preparing the crosslinking type waterborne polyurethane into PU microfiber leather, wherein the microfiber leather is kept for 10min under the condition that the load is 1kg, and the complete recovery time is 30-180 seconds after the load is removed; the PU microfiber leather is characterized in that the diameter of a test ring is as follows: phi =20mm, and a softness of 5 to 7 mm.

Description

Waterborne polyurethane emulsion and preparation method and application thereof
Technical Field
The invention belongs to the technical field of preparation of aqueous polyurethane emulsion, and relates to aqueous polyurethane emulsion, a preparation method thereof and application thereof to microfiber leather.
Background
The conventional water-based polyurethane is of a straight-chain structure, has low molecular weight, is not crosslinked after being cured, and has poor weather resistance in practical application because ionic groups such as carboxylate radicals and sulfonate radicals in molecular chain segments influence the mechanical strength and water resistance of polyurethane products. The mechanical strength, hydrolysis resistance and the like of polyurethane can be improved by performing crosslinking modification on waterborne polyurethane, and a conventional scheme is to add multifunctional small molecular monomers or macrotriol to improve the crosslinking modification of waterborne polyurethane, for example, in patent 201010299939.4 (a synthesis method of a non-woven fabric reinforced waterborne polyurethane emulsion), trimethylolpropane is used as an internal crosslinking agent to improve the strength, wear resistance and high water resistance of waterborne polyurethane. However, the crosslinking degree of the polyurethane obtained by the method using the multifunctional small molecular monomer or the macromolecule triol is not high, and the space for improving the performance of the polyurethane product is limited.
The double bond crosslinking mode is verified as being capable of greatly improving the mechanical strength of the material as early as in the rubber vulcanization process, and some researches report that double bonds are introduced on a polyurethane molecular chain to improve the mechanical property, hydrolysis resistance and the like of the material at present, for example, CN108912296B crosslinking type waterborne polyurethane and a preparation method thereof, wherein waterborne polyurethane emulsion is synthesized firstly, then free radical copolymerization reaction is carried out on multi-double bond castor oil and waterborne polyurethane, and the multi-double bond castor oil is connected into a waterborne polyurethane structure to synthesize the crosslinking type waterborne polyurethane with a space network structure, so that the mechanical property of the crosslinking type waterborne polyurethane is improved; the space density in the polymer is increased, the space is reduced, water molecules are difficult to enter, and the water resistance is improved. However, when the carboxylic acid type and sulfonic acid type aqueous polyurethane emulsions are prepared at present, the whole structure can be subjected to three-dimensional interpenetrating crosslinking by introducing double-bond group crosslinking, the prepared resin is applied to microfiber impregnation, and the obtained microfiber leather has a severe rubber feel, a hard hand feel and quick rebound.
Therefore, there is a need to develop an effective modification technique for aqueous polyurethane, so that the obtained aqueous polyurethane product can maintain the flexible touch of the aqueous polyurethane and improve the mechanical properties, hydrolysis resistance and aging resistance of the aqueous polyurethane.
Disclosure of Invention
In order to solve the problems of insufficient mechanical strength, aging resistance and water resistance improvement or hardening of water-based hand feeling caused by formation of a three-dimensional interpenetrating network due to integral crosslinking of molecular chains in the modified water-based polyurethane in a crosslinking mode in the prior art, when the water-based polyurethane emulsion is prepared, micromolecule mono-functionality sulfonate containing double bonds is used for reaction, the double bonds are gathered on the surface of emulsion particles along with sulfonate groups, and the synthesized polyurethane emulsion is of a linear structure; and then a vulcanizing agent is used for performing cross-linking reaction on double bonds on the surface to form a hard shell with high strength, hydrolysis resistance and aging resistance, the interior of emulsion particles is not cross-linked, and a flexible soft segment structure of polyurethane is reserved, so that the polyurethane has excellent flexibility and slow recovery, and compared with the conventional polyurethane, the flexibility and slow recovery have good retentivity when the material is subjected to a hot oxygen environment, a water/solvent corrosion environment and the like due to the protection of a shell.
The invention aims to provide a crosslinking type waterborne polyurethane emulsion, wherein a waterborne polyurethane molecular chain contains double bonds and sulfonic groups, the double bonds and the sulfonic groups are simultaneously arranged on a structural unit, and the waterborne polyurethane forms a crosslinking structure through a vulcanization process, so that polyurethane emulsion particles are obtained and have a core-shell structure, the shell crosslinking degree is high, the core is not crosslinked, and the core is soft and hard.
The second purpose of the invention is to provide a preparation method of the crosslinking type aqueous polyurethane emulsion, which comprises the steps of reacting trifunctional polyalcohol with excessive diisocyanate, then reacting with micromolecule monofunctional salt containing double bonds and sulfonic groups, and controlling to synthesize an intermediate substance with 1-2 chain segments A at the tail end by determining the addition amount of reaction raw materials.
The invention also aims to provide the application of the crosslinking type waterborne polyurethane emulsion to microfiber leather.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a preparation method of water-based polyurethane emulsion comprises the steps of carrying out vulcanization reaction on crosslinkable water-based polyurethane emulsion and a vulcanizing agent, and then carrying out centrifugal treatment to obtain crosslinked water-based polyurethane emulsion;
the preparation steps of the crosslinkable aqueous polyurethane emulsion are as follows:
(a) reacting oligomer triol with excessive diisocyanate, and then adding monohydric alcohol containing double bond sulfonic groups for synthetic reaction;
(b) then sequentially adding oligomer dihydric alcohol and diisocyanate, adding a chain extender I and a solvent, and continuously reacting to obtain a prepolymer; the chain extender I is micromolecular dihydric alcohol;
(c) adding a mixture of ice water and an emulsifier into the prepolymer, adding a chain extender II aqueous solution, and continuously stirring to prepare an emulsion; the chain extender II is micromolecular diamine;
(d) removing the solvent in the emulsion to prepare a crosslinkable aqueous polyurethane emulsion containing carbon-carbon double bonds and sulfonic acid groups; the solid content of the crosslinkable aqueous polyurethane emulsion is 40-55%.
As a preferred technical scheme:
according to the preparation method of the waterborne polyurethane emulsion, the raw materials for the vulcanization reaction are as follows in parts by weight:
100 parts of crosslinkable aqueous polyurethane emulsion;
0.2-1 part of a vulcanizing agent;
0.5-1 part of a vulcanization accelerator;
0.05-0.2 part of defoaming agent;
the centrifugal treatment after the vulcanization reaction specifically comprises the following steps: and (3) carrying out heat preservation and vulcanization for 5-10 hours at the vulcanization reaction temperature of 50-60 ℃, cooling to room temperature, and carrying out centrifugation treatment at 10000-15000 r/min.
In the preparation method of the waterborne polyurethane emulsion, the vulcanizing agent is sulfur; the vulcanization accelerator is zinc diethyl dithiocarbamate or sodium di-n-butyl dithiocarbamate; the defoaming agent is organic silicon emulsion.
In the preparation method of the aqueous polyurethane emulsion, in the step (a), the reaction conditions of the oligomer triol and the excess diisocyanate are as follows: heating to 80-90 ℃, and reacting for 1-2 hours in a heat preservation manner; the conditions of the synthesis reaction are as follows: the temperature is 50-60 ℃, and the reaction is carried out for 1-2 hours in a heat preservation way;
in the step (b), the sequence is as follows: adding oligomer dihydric alcohol, uniformly stirring, performing heat preservation reaction for 30-60 min, adding diisocyanate, stirring for 30-60 min, adding a chain extender I and a solvent, stirring, heating to 80-90 ℃, performing heat preservation reaction for 2-3 hours, and then cooling to 20-30 ℃;
in the step (c), after the mixture of ice water and the emulsifier is added into the prepolymer, the aqueous solution of the chain extender II is added and continuously stirred to prepare the emulsion, and the specific process comprises the following steps: adding a mixture of ice water and an emulsifier (FAX 2A1 from DOW company) into the prepolymer at a constant speed under the high-speed stirring of 1000-1400 r/min, dispersing the prepolymer, continuing stirring for 5-10 min, adjusting the rotating speed to 400-500 r/min, adding a chain extender II aqueous solution, and continuing stirring for 3-5 hours to obtain an emulsion;
in the step (d), the conditions for removing the solvent in the emulsion are as follows: the temperature is 40-45 ℃, and the vacuum pumping is carried out until the pressure is less than or equal to-0.08 MPa.
In the preparation method of the aqueous polyurethane emulsion, in the preparation process of the crosslinkable aqueous polyurethane emulsion, the total mole number of hydroxyl groups of the oligomer triol, the oligomer diol and the double-bond sulfonic group-containing monohydric alcohol is as follows: the total mole number of active end groups (hydroxyl and amino) in the chain extender I and the chain extender II is 1: 1.3-2.5;
the molar ratio of the oligomer triol to the monohydric alcohol containing the double-bond sulfonic group is 1: 2-3.8;
the molar addition amount of the oligomer dihydric alcohol is 11.7-35 times that of the oligomer trihydric alcohol;
the molar ratio of the chain extender I to the chain extender II is 1: 0.5-2; in the water solution of the chain extender II, the mass concentration of the chain extender II is 20-30%;
in the preparation process of the prepolymer, the total mole number of isocyanate groups (-NCO) of diisocyanate in the system is as follows: the total mole number of hydroxyl groups in the system is 1.35-2.14: 1;
the excess means that the molar charge ratio of the oligomer triol to the diisocyanate is 1: 3.08-4.
Adding the remaining diisocyanate in step (b) to match the total number of moles of amino and hydroxyl groups in the system to the total consumption of the amino and hydroxyl groups by reaction with isocyanate groups;
the addition amount of the solvent is 10-15 wt% of the crosslinkable aqueous polyurethane emulsion, the addition amount of the ice water is 40-59 wt% of the crosslinkable aqueous polyurethane emulsion, and the addition amount of the emulsifier is 1-5 wt% of the crosslinkable aqueous polyurethane emulsion.
According to the preparation method of the waterborne polyurethane emulsion, in the step (a), the oligomer triol is polyether triol, and the number average molecular weight is 3000-8000 g/mol, preferably 5000 g/mol; the diisocyanate is more than one of isophorone diisocyanate (IPDI), 4' -dicyclohexyl methane diisocyanate (HMDI) and Hexamethylene Diisocyanate (HDI); the monohydric alcohol containing the double-bond sulfonic group is 3-allyloxy-2-hydroxy-1-propane sulfonic acid sodium salt (AHPS) or sodium hydroxypropyl methacrylate (HPMAS).
In the preparation method of the aqueous polyurethane emulsion, in the step (b), the oligomer dihydric alcohol is polyether dihydric alcohol or polyester dihydric alcohol, and the number average molecular weight is 1000-3000 g/mol, preferably 2000 g/mol; the chain extender I is ethylene glycol; the solvent is acetone.
In the above preparation method of the aqueous polyurethane emulsion, the polyether diol is polytetrahydrofuran diol (PTMG), and the polyester diol is preferably at least one of polycarbonate diol (PCDL) and polycaprolactone diol (PCL).
In the preparation method of the aqueous polyurethane emulsion, in the step (c), the chain extender II is ethylenediamine, hydrazine hydrate, Isophoronediamine (IPDA) or 4, 4-diaminodicyclohexylmethane (HMDA).
The invention also provides a waterborne polyurethane emulsion, which comprises crosslinking waterborne polyurethane, an emulsifier and deionized water;
the molecular chain of the crosslinking type waterborne polyurethane contains 0.5-2 wt% of chain segment A and 99.5-98 wt% of chain segment B; the chain segment A is connected with the chain segment B by a carbamate group;
the chain segment A is composed of structural units containing carbon-carbon double bonds and hydrophilic groups; the hydrophilic group is a sulfonic group; the chain segment A is obtained by reacting monohydric alcohol containing double bond sulfonic group with diisocyanate;
the chain segment B is a polyurethane chain segment containing ether bonds or ester bonds, and the chain segment B does not contain hydrophilic groups and carbon-carbon double bonds.
As a preferred technical scheme:
the waterborne polyurethane emulsion comprises, by weight, 40-55% of cross-linking waterborne polyurethane, 1-5% of an emulsifier, and the balance deionized water.
The waterborne polyurethane emulsion has the emulsion particle size of 200-500 nm.
The crosslinking mode of the crosslinking type waterborne polyurethane is vulcanization crosslinking of carbon-carbon double bonds; the cross-linked waterborne polyurethane emulsion particle has a shell-core structure, and the core is soft and hard.
The invention also provides an application of the waterborne polyurethane emulsion on microfiber leather, wherein the crosslinked waterborne polyurethane is prepared into PU microfiber leather, and the specific process comprises the following steps: the sea-island fiber non-woven fabric (material COPET/PET, gram weight 350 g/m)2Density 0.28g/cm3) And (e) adding the aqueous polyurethane emulsion obtained in the step (e) to carry out impregnation (emulsion concentration: 40 percent, the liquid carrying rate is 150 percent), curing, fiber opening (NaOH solution with the mass fraction of 5 percent, padding for 30min at 85 ℃), water washing, neutralizing and drying to prepare PU microfiber leather with the thickness of 1.0 mm; the PU microfiber leather has slow rebound resilience, namely the PU microfiber leather is kept for 10min under the condition that the load is 1kg, and the complete recovery time is 30-180 seconds after the load is removed; PU microfiber leather (1.0mm)Testing the diameter of the ring: a softness of 5 to 7mm under the condition of phi being 20 mm; the tensile load of the PU microfiber leather (1.0mm) is more than or equal to 300N/2.5cm, the tearing load is more than or equal to 80N, the peeling load is more than or equal to 130N/3cm, and the hydrolysis peeling load is more than or equal to 110N/3 cm.
The principle of the invention is as follows:
the invention creatively introduces a molecular chain segment A which is composed of structural units containing double bonds and hydrophilic groups and has the crosslinkability and a polyurethane molecular chain segment B on a polyurethane molecular chain, wherein the structural units of the chain segment A contain double bonds and sulfo groups, and the chain segment B contains a polyurethane soft segment and a polyurethane hard segment; the sulfo group has hydrophilicity, the polyurethane chain segment without the hydrophilic group is a hydrophobic chain segment, the structure hydrophilicity difference between the chain segment A and the chain segment B ensures that the surface of the formed polyurethane emulsion particle is a shell formed by the chain segment A, the interior of the formed polyurethane emulsion particle is a core formed by the chain segment B, the chain segment A contains double bonds, and because the double bonds are enriched on the surface of the emulsion particle along with hydrophilic groups, the vulcanization crosslinking is easy under the action of a vulcanizing agent in aqueous solution, and the crosslinking points are all on the surface, thereby shortening the crosslinking reaction time, generating a large amount of new chemical bonding of the molecular chain segment due to the vulcanization process, greatly improving the mechanical property, the stability, the creep resistance and the like of the shell-shaped structure of the emulsion particle; since segment B has no vulcanizable double bonds, this chemical bonding is only at the surface of the emulsion particles; and on the other hand, the segment B keeps the softness and elasticity of polyurethane, so that the finally obtained crosslinking type water-based polyurethane emulsion particle has the characteristic of hard core and soft shell.
Through experimental research, when the chain segment B contains a soft segment with a polyether structure, excellent slow resilience is shown, the PU microfiber leather made of the polyurethane emulsion has soft hand feeling, and the slow resilience endows the material with comfortable touch experience.
By adjusting the proportion of the chain segment A, B forming the shell-core structure, the weight percentage of the chain segment A is 0.5-2 wt%, and the weight percentage of the chain segment B is 99.5-98 wt%, the material has excellent comprehensive performances such as mechanics, aging resistance, hydrolysis resistance and the like, and has slow rebound and better flexibility. When the chain segment A is too much, the crosslinking degree of the whole molecular chain is too high, the mechanical property of the material is improved, but the too high crosslinking degree enables the movement capability of the whole molecular chain to be bound, and when the external force acting on the molecular chain is removed, the material is quickly rebounded like a spring, so that the hand feeling of the material is not good; when the chain segment B is too much, the number of cross-linking points is too small, and the amplitude of the performance improvement of the material is relatively small.
Experiments have found that when polyether polyols are used as the oligomer diols or oligomer triols, the finished polyurethane microfiber leather product obtained has a softer hand compared to other types of polyols.
Advantageous effects
The emulsion particles of the crosslinking type waterborne polyurethane emulsion have a structure with a soft core and a hard shell, wherein the hard shell is caused by high crosslinking of the surface, and the crosslinking structure ensures that the resin has good temperature resistance, solvent resistance, hydrolysis resistance and weather resistance; when the method is applied to different microfiber processes, the prepared finished product has low thickness loss rate; the core is soft, because of the polyurethane soft segment coated in the core, when external force acts on the shell-core structure, stress is transmitted into the core through chemical bonds, energy is stored through elastic movement of molecular chain segments in the core, and the stress is recovered when the external force is eliminated, the crosslinked polyurethane has good resilience, and the prepared finished product has good restorability and no crease mark; and because of the protection of 'hard shell', the molecular chain segment of the 'soft core' is difficult to generate molecular chain damage such as aging degradation under the conditions of temperature, illumination, solvent and the like, and compared with the conventional PU, the soft PU has good softness and rebound resilience retentivity.
Drawings
FIG. 1 is a polymerization process in which, in the synthesis of a prepolymer for a crosslinkable aqueous polyurethane emulsion, a monohydric alcohol containing double bond sulfonic acid groups reacts with one of the trifunctional isocyanate groups of the reaction product of an oligomer triol and excess diisocyanate;
FIG. 2 shows the polymerization process of the reaction of a monohydric alcohol containing double bond sulfonic groups with two of the trifunctional isocyanate groups of the reaction product of an oligomeric triol and excess diisocyanate in the synthesis of a prepolymer of a crosslinkable aqueous polyurethane emulsion.
Detailed Description
The invention will be further illustrated with reference to specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.
The application of the waterborne polyurethane emulsion in the microfiber leather is to prepare the crosslinking waterborne polyurethane into PU microfiber leather, and the specific process is as follows: the sea-island fiber non-woven fabric (material COPET/PET, gram weight 350 g/m)2Density 0.28g/cm3) The aqueous polyurethane emulsion obtained in step (e) in the following examples was put into a container, and impregnation was performed (emulsion concentration: 40 percent, the liquid carrying rate is 150 percent), solidification, fiber opening (NaOH solution with the mass fraction of 5 percent, padding for 30min at 85 ℃), water washing, neutralization and drying to prepare the PU microfiber leather with the thickness of 1.0 mm.
The test method adopted by the invention is as follows:
temperature resistance of the aqueous polyurethane emulsion: the temperature resistance of the waterborne polyurethane is evaluated by preparing a polyurethane resin film from the waterborne polyurethane emulsion, and in order to compare the performance of the waterborne polyurethane, the resin film is prepared by adopting the following same raw materials and processes: weighing a certain amount of resin emulsion (waterborne polyurethane emulsion) into a 150 x 150mm watch glass, standing at normal temperature for 24h, and then drying at 80 ℃ for 10min and 140 ℃ for 10 min. Cutting the prepared resin film into a rectangle with the size of 25 x 100mm, hanging the rectangle in an oven at the temperature of 180 ℃, keeping the rectangle for 10min, observing the deformation quantity of the resin film, wherein the deformation quantity is (the current length-the original length)/the original length, and when the deformation quantity is less than or equal to 3%, the temperature resistance under the test condition is considered to meet the requirement. The temperature resistance of the waterborne polyurethane emulsion meets the requirement.
Softness of PU microfiber leather: the softness of the microfiber leather is measured by using a leather softness tester, and the model of the leather softness tester is as follows: QB-8326, Shanghai Qingbo test Equipment, Inc. The test method comprises the following steps: 1) firstly, a test ring with the diameter of 20mm is used on a test seat of a testing machine; 2) Using a metal flat plate equipped on a machine table to zero a machine dial; 3) pressing the sample into a test seat of a testing machine; 4) after the sample is pressed in, the pointer on the testing machine can change, after the pointer is stabilized, the corresponding numerical value is recorded, and the testing precision is 0.1 mm; 5) the values at three different points were tested and averaged.
Slow rebound resilience of PU microfiber leather: folding the PU microfiber leather in half, carrying a load of 1kg, keeping for 10min, removing pressure, opening the PU microfiber leather, and recording the recovery performance and the complete recovery time of the crease within 10 min.
Mechanical properties of the PU microfiber leather: the testing method is characterized in that a GB/T8949-2008 standard is adopted to test the tensile load, the tearing load and the peeling load, a testing instrument is a computer system tensile testing machine, and the model of the computer system tensile testing machine is as follows: AI-7000-S of Taiwan high-speed railway;
hydrolysis peeling load of PU microfiber leather: the method adopts the GB/T8949-2008 standard to test the peeling load, the instrument is a computer system tensile testing machine, and the model of the computer system tensile testing machine is as follows: AI-7000-S of Taiwan high-speed railway; the test method comprises the following steps: cutting a 150mm by 240mm (warp and weft) test sample along the warp (weft) direction of the prepared PU microfiber leather, immersing the cut sample strip into a NaOH aqueous solution with the mass fraction of 10%, and sealing and soaking for 24 hours; taking out the sample, washing the sample with clear water until the pH value is close to 7, and drying the sample for later use; coating glue on the surfaces of the samples to enable the two samples to be attached to each other, extruding for 3 times by a compression roller and drying; the materials were tested for hydrolytic peel load according to GB/T8949.
The correspondence between substances and their english abbreviations in the present invention is as follows:
isophorone diisocyanate (IPDI), 4' -dicyclohexylmethane diisocyanate (HMDI), Hexamethylene Diisocyanate (HDI), 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt (AHPS), sodium Hydroxypropanesulfonate (HPMAS), polytetrahydrofuran diol (PTMG), polycarbonate diol (PCDL), polycaprolactone diol (PCL), ethylenediamine, hydrazine hydrate, isophorone diamine (IPDA), 4-diaminodicyclohexylmethane (HMDA).
As shown in FIGS. 1 and 2, in the present invention, an oligomer triol is reacted with an excess of diisocyanate to obtain a trifunctional isocyanate group-containing prepolymer; then putting monohydric alcohol containing double bond sulfonic group for synthesis reaction, wherein the hydroxyl of the monohydric alcohol reacts with one isocyanate of the prepolymer, as shown in figure 1; the reactivity of the remaining two unreacted isocyanates with hydroxyl groups is greatly reduced after the reaction, but a small amount of the remaining hydroxyl groups of the monoalcohol still reacts with one of the remaining isocyanates, as shown in FIG. 2.
Then sequentially adding oligomer dihydric alcohol and diisocyanate, adding a chain extender I and a solvent, and continuously reacting to obtain a prepolymer; the chain extender I is micromolecular dihydric alcohol; adding a mixture of ice water and an emulsifier into the prepolymer, adding a chain extender II aqueous solution, and continuously stirring to prepare an emulsion; the chain extender II is micromolecular diamine; the reaction of this part is continued to form polyurethane molecular chains (composed of segment a, urethane group and segment B) on the remaining isocyanate groups, as shown in the last reaction steps of fig. 1 and 2.
Example 1
A preparation method of aqueous polyurethane emulsion and PU microfiber leather comprises the following steps:
preparing raw materials according to the following molar ratio: total moles of hydroxyl groups of oligomer triol, oligomer diol and double bond sulfonic group-containing monool: the total mole number of active end groups (hydroxyl and amino) in the chain extender I (ethylene glycol) and the chain extender II is 1: 1.3;
the molar ratio of the oligomer triol to the monohydric alcohol containing the double-bond sulfonic group is 1: 2;
the molar addition amount of the oligomer dihydric alcohol is 25 times of that of the oligomer trihydric alcohol;
the molar ratio of the chain extender I to the chain extender II is 1: 0.5;
the chain extender II is ethylenediamine;
the oligomer dihydric alcohol is PTMG with the number average molecular weight of 3000 g/mol;
the oligomer triol is Puranol G5030, optimized chemical, with a number average molecular weight of 5000G/mol;
the diisocyanate is IPDI;
the monohydric alcohol containing double bond sulfonic group is AHPS;
(a) mixing oligomer trihydric alcohol and excessive diisocyanate, heating to 80 ℃, reacting for 2 hours under heat preservation, adding monohydric alcohol containing double bond sulfonic group for synthetic reaction at 50 ℃, and preserving heat for 2 hours; wherein the molar charge ratio of the oligomer triol to the diisocyanate is 1: 3.08;
(b) sequentially adding oligomer dihydric alcohol, uniformly stirring, then carrying out heat preservation reaction for 30min, adding diisocyanate, stirring for 45min, adding chain extender I and acetone, stirring, heating to 80 ℃, carrying out heat preservation reaction for 3 hours, and then cooling to 20 ℃; adding a chain extender I and acetone, and continuously reacting to obtain a prepolymer;
in step (a) and step (b), the total moles of isocyanate groups (-NCO) of the diisocyanate added: the total mole number of hydroxyl in the system is 1.35: 1;
(c) adding a mixture of ice water and an emulsifier (FAX 2A1 from DOW company) into the prepolymer at a constant speed under high-speed stirring of 1000r/min, dispersing the prepolymer, continuing stirring for 10min, adjusting the rotating speed to 400r/min, adding a chain extender II aqueous solution, and continuing stirring for 5 hours to obtain an emulsion; in the aqueous solution of the chain extender II, the mass concentration of the chain extender II is 20 percent;
(d) removing acetone in the emulsion at the temperature of 40 ℃ and under the condition of vacuumizing to-0.08 MPa to prepare a crosslinkable aqueous polyurethane emulsion containing carbon-carbon double bonds and sulfonic acid groups;
wherein the solid content of the crosslinkable aqueous polyurethane emulsion is 40 percent;
(e) carrying out vulcanization reaction on the crosslinkable aqueous polyurethane emulsion and the following raw materials at the temperature of 50 ℃, carrying out heat preservation and vulcanization for 10 hours, cooling to 23 ℃, and then carrying out centrifugal treatment at the rotation speed of 10000r/min to obtain the aqueous polyurethane emulsion; wherein the raw materials for the vulcanization reaction are as follows in parts by weight:
100 parts of crosslinkable aqueous polyurethane emulsion;
0.2 part of sulfur;
0.5 part of vulcanization accelerator (zinc diethyldithiocarbamate);
0.05 part of organic silicon emulsion (Daokangning DK-1247);
preparing aqueous polyurethane emulsion, which comprises 40% of crosslinking aqueous polyurethane and 4% of deionized water in percentage by weight, and the balance of deionized water; wherein, the molecular chain of the crosslinkable waterborne polyurethane contains 0.6 wt% of chain segment A and 99.4 wt% of chain segment B; the chain segment A is connected with the chain segment B by a carbamate group; the chain segment A is a chain segment consisting of structural units containing carbon-carbon double bonds and sulfonic groups, which are prepared by reacting monohydric alcohol containing double bond sulfonic groups with diisocyanate; the chain segment B is a polyurethane chain segment containing ether bonds, and the polyurethane chain segment containing ether bonds does not contain hydrophilic groups and carbon-carbon double bonds.
The particle size of emulsion particles in the waterborne polyurethane emulsion is 450nm, and the emulsion particles have a shell-core structure, wherein the core is soft and the shell is hard;
the temperature resistance test result of the aqueous polyurethane emulsion is as follows: the deformation amount at 180 ℃ is 1.5%;
(f) preparing the crosslinking type waterborne polyurethane into PU microfiber leather with the thickness of 1.0 mm;
the prepared PU microfiber leather has slow rebound resilience, namely the PU microfiber leather is kept for 10min under the load of 1kg, and the complete recovery time after the load is removed is shown in table 1; the softness of the PU microfiber leather is shown in Table 1, and the diameter of the test ring is as follows: phi is 20 mm; the tensile load, the tearing load, the peeling load and the hydrolysis peeling load of the PU microfiber leather are shown in tables 1, 1 and 1 respectively
Comparative example 1
Comparative example 1 is substantially the same as example 1 except that a highly crosslinked polyurethane emulsion was prepared by using a hydroxyl-terminated polybutadiene containing double bonds but no sulfonic acid groups instead of a monohydric alcohol AHPS containing double bonds and sulfonic acid groups, the PU fiber prepared from the emulsion had the same excellent mechanical properties, and the tensile load of PU microfiber leather reached 312N/2.5cm, but the PU microfiber leather had the disadvantages of extremely poor softness and slow rebound effect, softness of 2.2mm, complete recovery time of < 1 second after load removal of the PU microfiber leather, and rapid deformation rebound, resulting in severe poor hand feeling. The reason is that the distribution of the double bond crosslinking on the whole molecular chain is disordered, the obtained polyurethane is crosslinked integrally under the action of a vulcanizing agent, and although the obtained material has excellent performance, the crosslinking structure enables the polymer to form a feeling similar to a spring, the softness is not good, and the requirement of a microfiber leather product is difficult to meet.
Comparative example 2
Comparative example 2 was substantially the same as example 1 except that the molar ratio of the oligomer triol to the double bond sulfonic acid group-containing monool was 1:6, and as a result, the double bond sulfonic acid group-containing monool reacted with all of the NCO groups bonded to the triol, and a large amount of the above-mentioned side reactions existed, so that the reactive functional group was lacking in the prepolymer, the B segment could not be formed on the prepolymer, and the polymerization failed.
Comparative example 3
Comparative example 3 is substantially the same as example 1 except that the molar ratio of the oligomer triol to the double bond sulfonic acid group-containing monool is 1:1, and the end result is that the segment A of the crosslinking-type aqueous polyurethane is too small to form a complete hard-shell soft-core structure, and the overall properties of the material, particularly the mechanical properties, are reduced. The waterborne polyurethane in the comparative example 3 is prepared into synthetic leather, and the mechanical property of the synthetic leather is obviously reduced by testing, and the method specifically comprises the following steps: a tensile load of 263N/2.5mm, a tear load of 73N, and a peel load of 126N/3 cm; the hydrolytic peeling load was 87N/3 cm.
Example 2
A preparation method of aqueous polyurethane emulsion and PU microfiber leather comprises the following steps:
preparing raw materials according to the following molar ratio: total moles of hydroxyl groups of oligomer triol, oligomer diol and double bond sulfonic group-containing monool: the total mole number of active end groups (hydroxyl and amino) in the chain extender I (ethylene glycol) and the chain extender II is 1: 2;
the molar ratio of the oligomer triol to the monohydric alcohol containing the double-bond sulfonic group is 1: 2.5;
the molar addition amount of the oligomer dihydric alcohol is 20 times that of the oligomer trihydric alcohol;
the molar ratio of the chain extender I to the chain extender II is 1: 1;
the chain extender II is hydrazine hydrate;
the oligomer dihydric alcohol is PCDL with the number average molecular weight of 1000 g/mol;
the oligomer triol is Puranol G5030, optimized chemical, with a number average molecular weight of 5000G/mol;
the diisocyanate is HMDI;
the monohydric alcohol containing the double bond sulfonic group is HPMAS;
(a) mixing oligomer trihydric alcohol with excessive diisocyanate, heating to 85 ℃, reacting for 1.5 hours under heat preservation, adding monohydric alcohol containing double bond sulfonic group for synthetic reaction at the temperature of 55 ℃, and preserving heat for 1.5 hours; wherein the molar charge ratio of the oligomer triol to the diisocyanate is 1: 3.2;
(b) sequentially adding oligomer dihydric alcohol, uniformly stirring, carrying out heat preservation reaction for 45min, adding diisocyanate, stirring for 30min, adding a chain extender I and acetone, stirring, heating to 85 ℃, carrying out heat preservation reaction for 2.5 hours, and then cooling to 25 ℃; adding a chain extender I and acetone, and continuously reacting to obtain a prepolymer;
in step (a) and step (b), the total moles of isocyanate groups (-NCO) of the diisocyanate added: the total mole number of hydroxyl in the system is 1.66: 1;
(c) adding a mixture of ice water and an emulsifier (FAX 2A1 from DOW company) into the prepolymer at a constant speed under high-speed stirring of 1200r/min, dispersing the prepolymer, continuing stirring for 7min, adjusting the rotating speed to 500r/min, adding a chain extender II aqueous solution, and continuing stirring for 3 hours to obtain an emulsion; in the aqueous solution of the chain extender II, the mass concentration of the chain extender II is 25 percent;
(d) removing acetone in the emulsion at the temperature of 45 ℃ under the condition of vacuumizing to-0.07 MPa to prepare the crosslinkable aqueous polyurethane emulsion containing carbon-carbon double bonds and sulfonic acid groups;
wherein the solid content of the crosslinkable aqueous polyurethane emulsion is 45 percent;
(e) carrying out vulcanization reaction on the crosslinkable aqueous polyurethane emulsion and the following raw materials, wherein the temperature of the vulcanization reaction is 55 ℃, the temperature is kept for 6 hours, the vulcanization reaction is carried out after the temperature is reduced to 25 ℃, and then the crosslinking aqueous polyurethane emulsion is subjected to centrifugal treatment under the condition that the rotating speed is 12000r/min to obtain the aqueous polyurethane emulsion; wherein the raw materials for the vulcanization reaction are as follows in parts by weight:
100 parts of crosslinkable aqueous polyurethane emulsion;
0.4 part of sulfur;
0.6 part of a vulcanization accelerator (zinc diethyldithiocarbamate);
0.09 part of organic silicon emulsion (Dow Corning DK-1247);
preparing a water-based polyurethane emulsion, which comprises 45 wt% of cross-linking water-based polyurethane and 2wt% of deionized water, wherein the balance is deionized water; wherein, the molecular chain of the crosslinkable waterborne polyurethane contains 0.9 wt% of chain segment A and 99.3 wt% of chain segment B; the chain segment A is connected with the chain segment B by a carbamate group; the chain segment A is a chain segment consisting of structural units containing carbon-carbon double bonds and sulfonic groups, which are prepared by reacting monohydric alcohol containing double bond sulfonic groups with diisocyanate; the chain segment B is a polyurethane chain segment containing ether bonds, and the polyurethane chain segment containing ether bonds does not contain hydrophilic groups and carbon-carbon double bonds.
The particle size of emulsion particles in the waterborne polyurethane emulsion is 300nm, and the emulsion particles have a shell-core structure, wherein the core is soft and the shell is hard;
the temperature resistance test result of the aqueous polyurethane emulsion is as follows: the deformation amount at 180 ℃ is 0.5%;
(f) preparing the crosslinking type waterborne polyurethane into PU microfiber leather with the thickness of 1.0 mm;
the prepared PU microfiber leather has slow rebound resilience, namely the PU microfiber leather is kept for 10min under the load of 1kg, and the complete recovery time after the load is removed is shown in table 1; the softness of the PU microfiber leather is shown in Table 1, and the diameter of the test ring is as follows: phi is 20 mm; the tensile load, the tearing load, the peeling load and the hydrolysis peeling load of the PU microfiber leather are shown in tables 1, 1 and 1, respectively.
Example 3
A preparation method of aqueous polyurethane emulsion and PU microfiber leather comprises the following steps:
preparing raw materials according to the following molar ratio: total moles of hydroxyl groups of oligomer triol, oligomer diol and double bond sulfonic group-containing monool: the total mole number of the active end groups (hydroxyl and amino) in the chain extender I (ethylene glycol) and the chain extender II is 1: 1.77;
the molar ratio of the oligomer triol to the monohydric alcohol containing the double-bond sulfonic group is 1: 3;
the molar addition amount of the oligomer dihydric alcohol is 35 times that of the oligomer trihydric alcohol;
the molar ratio of the chain extender I to the chain extender II is 1: 1.5;
the chain extender II is IPDA;
the oligomer dihydric alcohol is PCL with the number average molecular weight of 2000 g/mol;
the oligomer triol is Puranol G5030, optimized chemical, with a number average molecular weight of 5000G/mol;
the diisocyanate is HDI;
the monohydric alcohol containing double bond sulfonic group is AHPS; (a) mixing oligomer trihydric alcohol with excessive diisocyanate, heating to 85 ℃, reacting for 1 hour under heat preservation, adding monohydric alcohol containing double bond sulfonic group for synthetic reaction at the temperature of 55 ℃, and preserving heat for 1 hour; wherein the molar charge ratio of the oligomer triol to the diisocyanate is 1: 3.5;
(b) sequentially adding oligomer dihydric alcohol, uniformly stirring, carrying out heat preservation reaction for 40min, adding diisocyanate, stirring for 50min, adding a chain extender I and acetone, stirring, heating to 85 ℃, carrying out heat preservation reaction for 2 hours, and then cooling to 30 ℃; adding a chain extender I and acetone, and continuously reacting to obtain a prepolymer;
in step (a) and step (b), the total moles of isocyanate groups (-NCO) of the diisocyanate added: the total mole number of hydroxyl in the system is 1.77: 1;
(c) adding a mixture of ice water and an emulsifier (FAX 2A1 from DOW company) into the prepolymer at a constant speed under the high-speed stirring of 1350r/min, continuously stirring for 5min after the prepolymer is dispersed, then adjusting the rotating speed to 450r/min, adding a chain extender II aqueous solution, and continuously stirring for 4 hours to obtain an emulsion; in the aqueous solution of the chain extender II, the mass concentration of the chain extender II is 25 percent;
(d) removing acetone in the emulsion at the temperature of 43 ℃ under the condition of vacuumizing to-0.08 MPa to prepare crosslinkable aqueous polyurethane emulsion containing carbon-carbon double bonds and sulfonic acid groups;
wherein the solid content of the crosslinkable aqueous polyurethane emulsion is 50 percent;
(e) carrying out vulcanization reaction on the crosslinkable aqueous polyurethane emulsion and the following raw materials, wherein the temperature of the vulcanization reaction is 60 ℃, the temperature is kept for vulcanization for 5 hours, and after the temperature is reduced to 26 ℃, the crosslinkable aqueous polyurethane emulsion is subjected to centrifugal treatment at the rotating speed of 12500r/min to obtain the aqueous polyurethane emulsion; wherein the raw materials for the vulcanization reaction are as follows in parts by weight:
100 parts of crosslinkable aqueous polyurethane emulsion;
0.6 part of sulfur;
0.7 part of a vulcanization accelerator (zinc diethyldithiocarbamate);
0.11 part of organic silicon emulsion (Daokangning DK-1247);
preparing aqueous polyurethane emulsion, which comprises cross-linking aqueous polyurethane and deionized water, wherein the cross-linking aqueous polyurethane accounts for 50 percent, the emulsifier accounts for 5 percent, and the balance is the deionized water; wherein, the molecular chain of the crosslinkable waterborne polyurethane contains 0.5 wt% of chain segment A and 99.5 wt% of chain segment B; the chain segment A is connected with the chain segment B by a carbamate group; the chain segment A is a chain segment consisting of structural units containing carbon-carbon double bonds and sulfonic groups, which are prepared by reacting monohydric alcohol containing double bond sulfonic groups with diisocyanate; the chain segment B is a polyurethane chain segment containing ether bonds, and the polyurethane chain segment containing ether bonds does not contain hydrophilic groups and carbon-carbon double bonds.
The particle size of emulsion particles in the waterborne polyurethane emulsion is 500nm, and the emulsion particles have a shell-core structure, wherein the core is soft and the shell is hard;
the temperature resistance test result of the aqueous polyurethane emulsion is as follows: the deformation amount at 180 ℃ is 2%;
(f) preparing the crosslinking type waterborne polyurethane into PU microfiber leather with the thickness of 1.0 mm;
the prepared PU microfiber leather has slow rebound resilience, namely the PU microfiber leather is kept for 10min under the load of 1kg, and the complete recovery time after the load is removed is shown in table 1; the softness of the PU microfiber leather is shown in Table 1, and the diameter of the test ring is as follows: phi is 20 mm; the tensile load, the tearing load, the peeling load and the hydrolysis peeling load of the PU microfiber leather are shown in tables 1, 1 and 1, respectively.
Example 4
A preparation method of aqueous polyurethane emulsion and PU microfiber leather comprises the following steps:
preparing raw materials according to the following molar ratio: total moles of hydroxyl groups of oligomer triol, oligomer diol and double bond sulfonic group-containing monool: the total mole number of the active end groups (hydroxyl and amino) in the chain extender I (ethylene glycol) and the chain extender II is 1: 1.82;
the molar ratio of the oligomer triol to the monohydric alcohol containing the double-bond sulfonic group is 1: 3.8;
the molar addition amount of the oligomer dihydric alcohol is 35 times that of the oligomer trihydric alcohol;
the molar ratio of the chain extender I to the chain extender II is 1: 1.8;
the chain extender II is HMDA;
the oligomer dihydric alcohol is prepared from 1:1 a mixture of PTMG having a number average molecular weight of 1000g/mol and PCDL having a number average molecular weight of 2000 g/mol;
the oligomer triol is Puranol G5030, optimized chemical, with a number average molecular weight of 5000G/mol;
the diisocyanate is HDI;
the monohydric alcohol containing the double bond sulfonic group is HPMAS;
(a) mixing oligomer trihydric alcohol with excessive diisocyanate, heating to 90 ℃, reacting for 1 hour under heat preservation, adding monohydric alcohol containing double bond sulfonic group for synthetic reaction at the temperature of 60 ℃, and preserving heat for 1 hour; wherein the molar charge ratio of the oligomer triol to the diisocyanate is 1: 3.8;
(b) sequentially adding oligomer dihydric alcohol, uniformly stirring, carrying out heat preservation reaction for 55min, adding diisocyanate, stirring for 55min, adding a chain extender I and acetone, stirring, heating to 90 ℃, carrying out heat preservation reaction for 2 hours, and then cooling to 25 ℃; adding a chain extender I and acetone, and continuously reacting to obtain a prepolymer;
in step (a) and step (b), the total moles of isocyanate groups (-NCO) of the diisocyanate added: the total mole number of hydroxyl in the system is 1.92: 1;
(c) adding a mixture of ice water and an emulsifier (FAX 2A1 from DOW company) into the prepolymer at a constant speed of 1400r/min under high-speed stirring, dispersing the prepolymer, continuing stirring for 8min, adjusting the rotating speed to 450r/min, adding a chain extender II aqueous solution, and continuing stirring for 4 hours to obtain an emulsion; in the water solution of the chain extender II, the mass concentration of the chain extender II is 30 percent;
(d) removing acetone in the emulsion at the temperature of 40 ℃ and under the condition of vacuumizing to-0.06 MPa to prepare the crosslinkable aqueous polyurethane emulsion containing carbon-carbon double bonds and sulfonic acid groups;
wherein the solid content of the crosslinkable aqueous polyurethane emulsion is 55 percent;
(e) carrying out vulcanization reaction on the crosslinkable aqueous polyurethane emulsion and the following raw materials, wherein the temperature of the vulcanization reaction is 55 ℃, the temperature is kept for 6 hours, the temperature is reduced to 24 ℃, and then the crosslinkable aqueous polyurethane emulsion is subjected to centrifugal treatment under the condition that the rotating speed is 15000r/min to obtain the aqueous polyurethane emulsion; wherein the raw materials for the vulcanization reaction are as follows in parts by weight:
100 parts of crosslinkable aqueous polyurethane emulsion;
0.8 part of sulfur;
0.8 part of vulcanization accelerator (sodium di-n-butyldithiocarbamate);
0.15 part of organic silicon emulsion (Daokangning DK-1247);
preparing aqueous polyurethane emulsion, which comprises 55% of crosslinking aqueous polyurethane and 3% of deionized water in percentage by weight, and the balance of deionized water; wherein, the molecular chain of the crosslinkable waterborne polyurethane contains 0.8 wt% of chain segment A and 99.2 wt% of chain segment B; the chain segment A is connected with the chain segment B by a carbamate group; the chain segment A is a chain segment consisting of structural units containing carbon-carbon double bonds and sulfonic groups, which are prepared by reacting monohydric alcohol containing double bond sulfonic groups with diisocyanate; the chain segment B is a polyurethane chain segment containing ether bonds, and the polyurethane chain segment containing ether bonds does not contain hydrophilic groups and carbon-carbon double bonds.
The particle size of emulsion particles in the waterborne polyurethane emulsion is 350nm, and the emulsion particles have a shell-core structure, wherein the core is soft and the shell is hard;
the temperature resistance test result of the aqueous polyurethane emulsion is as follows: the deformation amount at 180 ℃ is 0.8%;
(f) preparing the crosslinking type waterborne polyurethane into PU microfiber leather with the thickness of 1.0 mm;
the prepared PU microfiber leather has slow rebound resilience, namely the PU microfiber leather is kept for 10min under the load of 1kg, and the complete recovery time after the load is removed is shown in table 1; the softness of the PU microfiber leather is shown in Table 1, and the diameter of the test ring is as follows: phi is 20 mm; the tensile load, the tearing load, the peeling load and the hydrolysis peeling load of the PU microfiber leather are shown in tables 1, 1 and 1, respectively.
Example 5
A preparation method of aqueous polyurethane emulsion and PU microfiber leather comprises the following steps:
preparing raw materials according to the following molar ratio: total moles of hydroxyl groups of oligomer triol, oligomer diol and double bond sulfonic group-containing monool: the total mole number of the active end groups (hydroxyl and amino) in the chain extender I (ethylene glycol) and the chain extender II is 1: 1.33;
the molar ratio of the oligomer triol to the double-bond sulfonic group-containing monohydric alcohol is 1: 3.67;
the molar addition amount of the oligomer dihydric alcohol is 11.7 times that of the oligomer trihydric alcohol;
the molar ratio of the chain extender I to the chain extender II is 1: 1.4;
the chain extender II is ethylenediamine;
the oligomer dihydric alcohol is PTMG with the number average molecular weight of 2500 g/mol;
the oligomer triol is Puranol G5030, optimized chemical, with a number average molecular weight of 5000G/mol;
the diisocyanate is a mixture of IPDI and HMDI in a mass ratio of 1: 1;
the monohydric alcohol containing double bond sulfonic group is AHPS;
(a) mixing oligomer trihydric alcohol with excessive diisocyanate, heating to 85 ℃, reacting for 1.5 hours under heat preservation, adding monohydric alcohol containing double bond sulfonic group for synthetic reaction at the temperature of 55 ℃, and preserving heat for 1.5 hours; wherein the molar feeding ratio of the oligomer triol to the diisocyanate is 1: 4;
(b) sequentially adding oligomer dihydric alcohol, uniformly stirring, then carrying out heat preservation reaction for 60min, adding diisocyanate, stirring for 60min, adding chain extender I and acetone, stirring, heating to 85 ℃, carrying out heat preservation reaction for 2.5 hours, and then cooling to 30 ℃; adding a chain extender I and acetone, and continuously reacting to obtain a prepolymer;
in step (a) and step (b), the total moles of isocyanate groups (-NCO) of the diisocyanate added: the total mole number of hydroxyl in the system is 1.54: 1;
(c) adding a mixture of ice water and an emulsifier (FAX 2A1 from DOW company) into the prepolymer at a constant speed under the high-speed stirring of 1100r/min, dispersing the prepolymer, continuing to stir for 7min, adjusting the rotating speed to 450r/min, adding a chain extender II aqueous solution, and continuing to stir for 4 hours to obtain an emulsion; in the aqueous solution of the chain extender II, the mass concentration of the chain extender II is 28 percent;
(d) removing acetone in the emulsion at the temperature of 45 ℃ under the condition of vacuumizing to-0.05 MPa to prepare crosslinkable aqueous polyurethane emulsion containing carbon-carbon double bonds and sulfonic acid groups;
wherein the solid content of the crosslinkable aqueous polyurethane emulsion is 45 percent;
(e) carrying out vulcanization reaction on the crosslinkable aqueous polyurethane emulsion and the following raw materials, wherein the temperature of the vulcanization reaction is 55 ℃, the temperature is kept for vulcanization for 7 hours, and after the temperature is reduced to 27 ℃, the crosslinkable aqueous polyurethane emulsion is subjected to centrifugal treatment at the rotation speed of 13000r/min to obtain the aqueous polyurethane emulsion; wherein the raw materials for the vulcanization reaction are as follows in parts by weight:
100 parts of crosslinkable aqueous polyurethane emulsion;
1 part of sulfur;
1 part of vulcanization accelerator (sodium di-n-butyldithiocarbamate);
0.16 part of organosilicon emulsion (Dow Corning DK-1247);
preparing aqueous polyurethane emulsion, which comprises 45% of crosslinking aqueous polyurethane and 1% of deionized water in percentage by weight, and the balance of deionized water; wherein, the molecular chain of the crosslinkable aqueous polyurethane contains 2wt% of chain segment A and 98wt% of chain segment B; the chain segment A is connected with the chain segment B by a carbamate group; the chain segment A is a chain segment consisting of structural units containing carbon-carbon double bonds and sulfonic groups, which are prepared by reacting monohydric alcohol containing double bond sulfonic groups with diisocyanate; the chain segment B is a polyurethane chain segment containing ether bonds, and the polyurethane chain segment containing ether bonds does not contain hydrophilic groups and carbon-carbon double bonds.
The particle size of emulsion particles in the waterborne polyurethane emulsion is 200nm, and the emulsion particles have a shell-core structure, wherein the core is soft and the shell is hard;
the temperature resistance test result of the aqueous polyurethane emulsion is as follows: the deformation amount at 180 ℃ is 0.3%;
(f) preparing the crosslinking type waterborne polyurethane into PU microfiber leather with the thickness of 1.0 mm;
the prepared PU microfiber leather has slow rebound resilience, namely the PU microfiber leather is kept for 10min under the load of 1kg, and the complete recovery time after the load is removed is shown in table 1; the softness of the PU microfiber leather is shown in Table 1, and the diameter of the test ring is as follows: phi is 20 mm; the tensile load, the tearing load, the peeling load and the hydrolysis peeling load of the PU microfiber leather are shown in tables 1, 1 and 1, respectively.
Example 6
A preparation method of aqueous polyurethane emulsion and PU microfiber leather comprises the following steps:
preparing raw materials according to the following molar ratio: total moles of hydroxyl groups of oligomer triol, oligomer diol and double bond sulfonic group-containing monool: the total mole number of active end groups (hydroxyl and amino) in the chain extender I (ethylene glycol) and the chain extender II is 1: 2.5;
the molar ratio of the oligomer triol to the monohydric alcohol containing the double-bond sulfonic group is 1: 3.8;
the molar addition amount of the oligomer dihydric alcohol is 35 times that of the oligomer trihydric alcohol;
the molar ratio of the chain extender I to the chain extender II is 1: 2;
the chain extender II is hydrazine hydrate;
the oligomer dihydric alcohol is PTMG with the number average molecular weight of 1000 g/mol;
the oligomer triol is Puranol G5030, optimized chemical, with a number average molecular weight of 5000G/mol;
the diisocyanate is HMDI;
the monohydric alcohol containing the double bond sulfonic group is HPMAS;
(a) mixing oligomer trihydric alcohol with excessive diisocyanate, heating to 80 ℃, reacting for 2 hours under heat preservation, adding monohydric alcohol containing double bond sulfonic group for synthetic reaction at the temperature of 60 ℃, and preserving heat for 1 hour; wherein the molar feeding ratio of the oligomer triol to the diisocyanate is 1: 4;
(b) sequentially adding oligomer dihydric alcohol, uniformly stirring, then carrying out heat preservation reaction for 50min, adding diisocyanate, stirring for 35min, adding chain extender I and acetone, stirring, heating to 80 ℃, carrying out heat preservation reaction for 3 hours, and then cooling to 20 ℃; adding a chain extender I and acetone, and continuously reacting to obtain a prepolymer;
in step (a) and step (b), the total moles of isocyanate groups (-NCO) of the diisocyanate added: the total mole number of hydroxyl in the system is 2.14: 1;
(c) adding a mixture of ice water and an emulsifier (FAX 2A1 from DOW company) into the prepolymer at a constant speed under the high-speed stirring of 1250r/min, dispersing the prepolymer, continuing to stir for 7min, then adjusting the rotating speed to 450r/min, adding a chain extender II aqueous solution, and continuing to stir for 4 hours to obtain an emulsion; in the aqueous solution of the chain extender II, the mass concentration of the chain extender II is 25 percent;
(d) removing acetone in the emulsion at the temperature of 45 ℃ under the condition of vacuumizing to-0.06 MPa to prepare the crosslinkable aqueous polyurethane emulsion containing carbon-carbon double bonds and sulfonic acid groups;
wherein the solid content of the crosslinkable aqueous polyurethane emulsion is 50 percent;
(e) carrying out vulcanization reaction on the crosslinkable aqueous polyurethane emulsion and the following raw materials, wherein the temperature of the vulcanization reaction is 55 ℃, the temperature is kept for vulcanization for 8 hours, and after the temperature is reduced to 25 ℃, the crosslinkable aqueous polyurethane emulsion is subjected to centrifugal treatment at the rotating speed of 12000r/min to obtain the aqueous polyurethane emulsion; wherein the raw materials for the vulcanization reaction are as follows in parts by weight:
100 parts of crosslinkable aqueous polyurethane emulsion;
0.5 part of sulfur;
0.8 part of vulcanization accelerator (sodium di-n-butyldithiocarbamate);
0.2 part of organic silicon emulsion (Daokangning DK-1247);
preparing aqueous polyurethane emulsion, which comprises cross-linking aqueous polyurethane and deionized water, wherein the content of the cross-linking aqueous polyurethane is 50 percent, the content of the emulsifier is 3 percent, and the balance is the deionized water according to weight percentage; wherein, the molecular chain of the crosslinkable waterborne polyurethane contains 0.8 wt% of chain segment A and 99.2 wt% of chain segment B; the chain segment A is connected with the chain segment B by a carbamate group; the chain segment A is a chain segment consisting of structural units containing carbon-carbon double bonds and sulfonic groups, which are prepared by reacting monohydric alcohol containing double bond sulfonic groups with diisocyanate; the chain segment B is a polyurethane chain segment containing ether bonds, and the polyurethane chain segment containing ether bonds does not contain hydrophilic groups and carbon-carbon double bonds.
The particle size of emulsion particles in the waterborne polyurethane emulsion is 360nm, and the emulsion particles have a shell-core structure, wherein the core is soft and the shell is hard;
the temperature resistance test result of the aqueous polyurethane emulsion is as follows: the deformation amount at 180 ℃ is 1 percent;
(f) preparing the crosslinking type waterborne polyurethane into PU microfiber leather with the thickness of 1.0 mm;
the prepared PU microfiber leather has slow rebound resilience, namely the PU microfiber leather is kept for 10min under the load of 1kg, and the complete recovery time after the load is removed is shown in table 1; the softness of the PU microfiber leather is shown in Table 1, and the diameter of the test ring is as follows: phi is 20 mm; the tensile load, the tearing load, the peeling load and the hydrolysis peeling load of the PU microfiber leather are shown in tables 1, 1 and 1, respectively.
TABLE 1
Performance index Unit of Example 1 Example 2 Example 3 Example 4 Example 5 Example 6
Complete recovery time after removing load Second of 150 80 180 100 30 120
The softness of the PU microfiber leather is mm 7 5 5.7 5.8 6.8 5.5
Tensile load of PU microfiber leather N/2.5cm 300 352 335 350 318 360
Tear load N 98 84 90 86 93 80
Peeling load N/3cm 155 138 143 140 150 130
Load of hydrolysis peeling N/3cm 135 126 130 119 130 110
Example 7
In substantial agreement with example 2, except that PTMG was substituted for PCDL, example 7 performed better in softness, and the softness of PU microfiber leather was tested to be 5.9 mm.
Example 8
In substantial agreement with example 3, except that the PCL was replaced by PTMG, example 8 performed better in softness, and the softness of PU microfiber leather was tested to be 6.3 mm.

Claims (13)

1. A preparation method of aqueous polyurethane emulsion is characterized by comprising the following steps: carrying out vulcanization reaction on the crosslinkable aqueous polyurethane emulsion and a vulcanizing agent, and then carrying out centrifugal treatment to obtain a crosslinked aqueous polyurethane emulsion;
the preparation steps of the crosslinkable aqueous polyurethane emulsion are as follows:
(a) reacting oligomer triol with excessive diisocyanate, and then adding monohydric alcohol containing double bond sulfonic groups for synthetic reaction;
(b) then sequentially adding oligomer dihydric alcohol and diisocyanate, adding a chain extender I and a solvent, and continuously reacting to obtain a prepolymer; the chain extender I is micromolecular dihydric alcohol;
(c) adding a mixture of ice water and an emulsifier into the prepolymer, adding a chain extender II aqueous solution, and continuously stirring to prepare an emulsion; the chain extender II is micromolecular diamine;
(d) removing the solvent in the emulsion to prepare a crosslinkable aqueous polyurethane emulsion containing carbon-carbon double bonds and sulfonic acid groups; the solid content of the crosslinkable aqueous polyurethane emulsion is 40-55%;
in the preparation process of the crosslinkable aqueous polyurethane emulsion, the total mole number of hydroxyl groups of the oligomer triol, the oligomer diol and the double-bond sulfonic group-containing monohydric alcohol is as follows: the total mole number of the active end groups in the chain extender I and the chain extender II is 1: 1.3-2.5;
the molar ratio of the oligomer triol to the monohydric alcohol containing the double-bond sulfonic group is 1: 2-3.8;
the molar addition amount of the oligomer dihydric alcohol is 11.7-35 times that of the oligomer trihydric alcohol;
the molar ratio of the chain extender I to the chain extender II is 1: 0.5-2; in the water solution of the chain extender II, the mass concentration of the chain extender II is 20-30%;
in the preparation process of the prepolymer, the total mole number of isocyanate groups of diisocyanate in the system is as follows: the total mole number of hydroxyl groups in the system is 1.35-2.14: 1;
the excess means that the molar charge ratio of the oligomer triol to the diisocyanate is 1: 3.08-4.
2. The preparation method of the waterborne polyurethane emulsion as claimed in claim 1, wherein the raw materials for the vulcanization reaction are as follows:
Figure FDA0003320329490000011
the centrifugal treatment after the vulcanization reaction specifically comprises the following steps: and (3) carrying out heat preservation and vulcanization for 5-10 hours at the vulcanization reaction temperature of 50-60 ℃, cooling to room temperature, and carrying out centrifugation treatment at 10000-15000 r/min.
3. The method for preparing an aqueous polyurethane emulsion according to claim 2, wherein the vulcanizing agent is sulfur; the vulcanization accelerator is zinc diethyl dithiocarbamate or sodium di-n-butyl dithiocarbamate; the defoaming agent is organic silicon emulsion.
4. The method of claim 1, wherein in step (a), the reaction conditions of the oligomer triol and the excess diisocyanate are as follows: heating to 80-90 ℃, and reacting for 1-2 hours in a heat preservation manner; the conditions of the synthesis reaction are as follows: the temperature is 50-60 ℃, and the reaction is carried out for 1-2 hours in a heat preservation way;
in the step (b), the sequence is as follows: adding oligomer dihydric alcohol, uniformly stirring, performing heat preservation reaction for 30-60 min, adding diisocyanate, stirring for 30-60 min, adding a small molecular dihydric alcohol chain extender and a solvent, stirring, heating to 80-90 ℃, performing heat preservation reaction for 2-3 hours, and then cooling to 20-30 ℃;
in the step (c), after the mixture of ice water and the emulsifier is added into the prepolymer, the aqueous solution of the chain extender II is added and continuously stirred to prepare the emulsion, and the specific process comprises the following steps: adding a mixture of ice water and an emulsifier into the prepolymer at a constant speed under high-speed stirring of 1000-1400 r/min, continuously stirring for 5-10 min after the prepolymer is dispersed, then adjusting the rotating speed to 400-500 r/min, adding a chain extender II aqueous solution, and continuously stirring for 3-5 hours to obtain an emulsion;
in the step (d), the conditions for removing the solvent in the emulsion are as follows: the temperature is 40-45 ℃, and the vacuum pumping is carried out until the pressure is less than or equal to-0.08 MPa.
5. The preparation method of the aqueous polyurethane emulsion according to claim 1, wherein the oligomer triol in the step (a) is a polyether triol, and the number average molecular weight is 3000-8000 g/mol; the diisocyanate is more than one of isophorone diisocyanate, 4' -dicyclohexylmethane diisocyanate and hexamethylene diisocyanate; the monohydric alcohol containing double bond sulfonic group is 3-allyloxy-2-hydroxy-1-propane sulfonic acid sodium salt or methacrylic acid hydroxypropyl sodium sulfonate.
6. The method for preparing the aqueous polyurethane emulsion according to claim 1, wherein the oligomer diol in the step (b) is polyether diol or polyester diol, and the number average molecular weight of the oligomer diol is 1000 to 3000 g/mol; the chain extender I is ethylene glycol; the solvent is acetone.
7. The method for preparing the aqueous polyurethane emulsion according to claim 6, wherein the polyether diol is polytetrahydrofuran diol, and the polyester diol is one or more of polycarbonate diol and polycaprolactone diol.
8. The method of claim 1, wherein the chain extender II in step (c) is ethylenediamine, hydrazine hydrate, isophoronediamine or 4, 4-diaminodicyclohexylmethane.
9. An aqueous polyurethane emulsion obtainable by the process according to any one of claims 1 to 8, characterized in that: comprises crosslinking type waterborne polyurethane and deionized water;
the crosslinking type waterborne polyurethane is obtained by vulcanizing a crosslinkable waterborne polyurethane emulsion;
the molecular chain of the crosslinking type waterborne polyurethane contains 0.5-2 wt% of chain segment A and 99.5-98 wt% of chain segment B; the chain segment A is connected with the chain segment B by a carbamate group;
the chain segment A is composed of structural units containing carbon-carbon double bonds and hydrophilic groups; the hydrophilic group is a sulfonic group; the chain segment A is obtained by reacting monohydric alcohol containing double bond sulfonic group with diisocyanate;
the chain segment B is a polyurethane chain segment containing ether bonds, and the polyurethane chain segment containing ether bonds does not contain hydrophilic groups and carbon-carbon double bonds.
10. The aqueous polyurethane emulsion according to claim 9, wherein the weight percentage of the cross-linked aqueous polyurethane is 40-55%, the weight percentage of the emulsifier is 1-5%, and the balance is deionized water.
11. The aqueous polyurethane emulsion according to claim 9, wherein the particle size of the emulsion particles of the aqueous polyurethane emulsion is 200 to 500 nm.
12. The aqueous polyurethane emulsion according to claim 11, wherein the crosslinking mode of the crosslinking aqueous polyurethane is vulcanization crosslinking of carbon-carbon double bonds; the cross-linked waterborne polyurethane emulsion particle has a shell-core structure, and the core is soft and hard.
13. The application of the waterborne polyurethane emulsion on microfiber leather according to any one of claims 9 to 12, wherein the waterborne polyurethane emulsion comprises the following components in percentage by weight: preparing the crosslinking type waterborne polyurethane into PU microfiber leather, keeping the PU microfiber leather under the load of 1kg for 10min, and completely recovering for 30-180 seconds after the load is removed; the PU microfiber leather is characterized in that the diameter of a test ring is as follows: phi is 20mm, and the softness is 5-7 mm; the tensile load of the PU microfiber leather is more than or equal to 300N/2.5cm, the tearing load is more than or equal to 80N, the peeling load is more than or equal to 130N/3cm, and the hydrolysis peeling load is more than or equal to 110N/3 cm.
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