CN114716643A

CN114716643A - Preparation method of sulfonic acid type waterborne polyurethane adhesive

Info

Publication number: CN114716643A
Application number: CN202210424834.XA
Authority: CN
Inventors: 李晓; 陈赛平; 张卫英; 叶一鸣
Original assignee: Fuzhou University
Current assignee: Fuzhou University
Priority date: 2022-04-22
Filing date: 2022-04-22
Publication date: 2022-07-08
Anticipated expiration: 2042-04-22
Also published as: CN114716643B

Abstract

The invention discloses a preparation method of a novel sulfonic acid type waterborne polyurethane adhesive, belonging to the technical field of adhesives. Firstly, carrying out Mannich reaction on sodium lignosulfonate, diethylenetriamine and formaldehyde to obtain sodium lignosulfonate amine, then reacting polyester polyol or polyether polyol with diisocyanate and a micromolecular polyol chain extender to obtain a polyurethane prepolymer, then adding a sulfonic hydrophilic chain extender, a monoamine chain extender and the sodium lignosulfonate amine to carry out chain extension reaction, shearing and dispersing at a high speed after the reaction is finished, removing acetone to obtain a water-based polyurethane emulsion, and finally adding a defoaming agent, a thickening agent and a curing agent to obtain the sulfonic water-based polyurethane adhesive. According to the invention, sodium lignosulfonate is introduced into the preparation of waterborne polyurethane, so that the high-solid-content waterborne polyurethane with stable storage is prepared, the peel strength and hydrolysis resistance of the waterborne polyurethane adhesive are improved, and the high-valued utilization of the sodium lignosulfonate is realized.

Description

Preparation method of sulfonic acid type waterborne polyurethane adhesive

Technical Field

The invention belongs to the technical field of adhesives, and particularly relates to a preparation method of a novel sulfonic acid type water-based polyurethane adhesive.

Background

The polyurethane adhesives are classified into solvent-based, solvent-free and aqueous polyurethane adhesives according to the use system. The solvent type polyurethane adhesive contains flammable, explosive, volatile, strong-odor and toxic organic solvents, so that pollution is caused during use, and great harm is brought. With the improvement of living standard and further improvement of environmental protection laws and regulations, the water-based polyurethane adhesive becomes the key development point at home and abroad.

The existing aqueous polyurethane adhesive has the defects of low solid content, poor hydrolysis resistance, poor peel strength and the like, and the carboxylic acid type aqueous polyurethane adhesive is mainly used in the market, carboxylate is weak acid and weak base salt, and the self-catalytic degradation of the carboxylate causes the degradation of the molecules of the polyurethane adhesive, so that the storage stability is reduced. The sulfonate is strong acid strong alkali salt, has higher ionization degree, can form a more stable double-electron-layer structure, is not easy to cause emulsion particles to generate aggregation and precipitation, can effectively improve the solid content of the waterborne polyurethane, and ensures that the waterborne polyurethane has good stability under the weak acid condition. However, the cost of the sulfonate is high, and particularly, the preparation process of the polyether or polyester sulfonate is complex, so that the wide application of the sulfonic acid type waterborne polyurethane adhesive is limited. Therefore, the development of a sulfonic acid type aqueous polyurethane adhesive with simple process, good stability, excellent comprehensive performance and low cost is an urgent need in the adhesive industry.

Lignin, as a second major plant biomass resource, is receiving more and more attention due to its wide source and low cost. The lignin has a rigid benzene ring structure and more functional groups, is introduced into polyurethane, and can improve the strength and toughness of the polyurethane material by utilizing the cross-linking network and the interface hydrogen bond effect between the lignin and a polyurethane matrix. Lignosulfonate (SL) is a derivative of lignin, contains hydrophilic groups (sulfonic acid group, carboxyl group and phenolic hydroxyl group) and hydrophobic groups (aromatic group and aliphatic group), belongs to a rigid anionic surfactant, and has good chelating capacity for iron and stannous ions. However, sodium lignosulfonate has a complex structure, large steric hindrance and low reaction activity, and has the problem of poor compatibility with waterborne polyurethane, so that how to effectively utilize sodium lignosulfonate to enhance the performance of waterborne polyurethane needs to be further explored.

Disclosure of Invention

The invention provides a preparation method of a novel sulfonic acid type water-based polyurethane adhesive, aiming at solving the problems in the prior art. According to the preparation method, firstly, sodium lignosulfonate is subjected to amination modification, and then sodium lignosulfonate amine obtained through modification and amine sulfonate are jointly used as hydrophilic chain extenders, so that the high-solid-content sulfonic acid type waterborne polyurethane with stable storage is prepared, and the peel strength and hydrolysis resistance of the waterborne polyurethane adhesive are improved. The obtained product basically does not contain organic solvent, is environment-friendly and safe, and realizes high-value utilization of the sodium lignosulfonate.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a sulfonic acid type waterborne polyurethane adhesive comprises the following steps:

(1) dissolving 20 parts by mass of sodium lignosulfonate, 10-16 parts by mass of diethylenetriamine and 4-6 parts by mass of formaldehyde solution (36 wt%) in 100 parts by mass of deionized water, adding 10 wt% of NaOH solution to adjust the pH value to 10-12, and reacting at 60-80 ℃ for 4-6 hours; then cooling the mixture to room temperature, slowly pouring the mixture into a large amount of absolute ethyl alcohol to precipitate a product, centrifugally separating the product, washing the product for 3 times by using the absolute ethyl alcohol, and then carrying out vacuum drying at 50 ℃ for 24 hours to obtain sodium lignosulfonate amine;

(2) adding 87 mass parts of polyester polyol or polyether polyol into a reactor after dehydration at the temperature of 100-120 ℃, adding 10-12 mass parts of diisocyanate, 0.03 mass part of micromolecular polyol chain extender and 0.01-0.02 mass part of organic metal catalyst, and reacting for 2-4 hours at the temperature of 70-85 ℃ until the residual NCO groups account for less than 0.96-1.72 percent of the mass of the prepolymer; then adding 30-80 parts by mass of acetone for reducing viscosity, adding a mixed solution formed by dissolving 0.05-3 parts by mass of sodium lignosulfonate amine, 0.5-2 parts by mass of sulfonate type hydrophilic chain extender and 0.1-1 part by mass of monoamine chain extender in 5 parts by mass of deionized water, and carrying out chain extension reaction for 0.5-1 h at 40-60 ℃ to obtain a polyurethane prepolymer;

(3) adding 90-150 parts by mass of deionized water into 190 parts by mass of 132-190 parts by mass of polyurethane prepolymer, carrying out high-speed shearing dispersion for 0.5-1 hour at 20-30 ℃, and then vacuumizing to remove acetone to obtain a waterborne polyurethane emulsion;

(4) adding 0.01-0.1 part by mass of defoaming agent, 0.01-0.2 part by mass of thickening agent and 0.1-1 part by mass of curing agent into 40 parts by mass of aqueous polyurethane emulsion, and uniformly mixing to obtain the sulfonic acid type aqueous polyurethane adhesive.

In the step (2), the polyester polyol is any one or more of polycaprolactone polyol, polycarbonate polyol and polyester adipate polyol, the polyether polyol is any one or more of polytetrahydrofuran polyol, ethoxy end-capped polymer glycol and propylene oxide polyether polyol, and the polyester adipate polyol is preferred.

In the step (2), the diisocyanate is any one or more of isophorone diisocyanate, hexamethylene diisocyanate, methylcyclohexyl isocyanate and toluene diisocyanate, preferably the combination of isophorone diisocyanate and hexamethylene diisocyanate, and the molar ratio is preferably 1: 1.

In the step (2), the micromolecular polyalcohol chain extender is any one or more of ethylene glycol, 1, 4-butanediol, 1, 6-hexanediol, neopentyl glycol and 1, 5-pentanediol, and 1, 4-butanediol is preferred.

In the step (2), the organic metal catalyst is any one or more of organic bismuth, organic tin, organic zirconium and bismuth-zinc alloy catalysts, such as dibutyltin oxide, tin dioctoate, dibutyltin dilaurate, tin bis- (2-ethylhexanoate), bismuth neodecanoate and bismuth 2-ethylhexanoate, and dibutyltin dilaurate is preferred.

The sulfonate type hydrophilic chain extender in the step (2) is any one or more of ethylenediamine ethyl sodium sulfonate and ethylenediamine propyl sodium sulfonate, and preferably ethylenediamine ethyl sodium sulfonate.

In the step (2), the monoamine chain extender is one or more of methylamine, ethylamine, propylamine, n-butylamine, dibutylamine, 2-aminobutane, 1-aminopentane, 2-aminopentane, 1-amino-2-propanol, 3-amino-1-propanol, ethanolamine and diethanolamine, and preferably diethanolamine.

The solid content of the aqueous polyurethane emulsion obtained in the step (3) is 30 to 60 weight percent, and preferably 40 to 55 weight percent.

The hydrophilicity of the sulfonic acid type waterborne polyurethane adhesive provided by the invention is mainly realized by an amine sulfonic acid type hydrophilic chain extender containing active hydrogen and sodium lignosulfonate amine, and neutralization is not needed, so that odor and VOC (volatile organic compounds) caused by low-boiling-point neutralizers such as triethylamine are avoided, and the environment-friendly performance is good. The sodium salt of the amine sulfonate belongs to strong acid strong base salt, is not easy to hydrolyze, so that the product has better water resistance, and simultaneously, the added sodium lignosulfonate can provide partial sulfonate to reduce the content of the sodium salt of the amine sulfonate, and can also react with isocyanate for crosslinking to protect ester bonds from hydrolysis. In addition, the sodium lignosulfonate amine has good chelating capacity for iron and stannous ions, can chelate metal ions in an organic tin catalyst, and improves the emulsion stability of the aqueous polyurethane.

Compared with the prior art, the preparation method has the beneficial effects that:

(1) according to the invention, through Mannich reaction, amination modification is carried out on sodium lignosulfonate to obtain sodium lignosulfonate amine, and the sodium lignosulfonate amine is used as a hydrophilic chain extender to carry out chain extension reaction with isocyanate, so that the high-solid-content waterborne polyurethane with high hard segment content and good stability is prepared.

(2) According to the invention, the traditional diamine chain extender is replaced by the sodium lignosulfonate amine and the monoamine chain extender, so that the water-based polyurethane adhesive with high solid content and good stability can be synthesized. Due to the characteristics of multiple rigid benzene ring structures and reactive groups of the lignosulphonate, the lignosulphonate can form a tighter cross-linked network with isocyanate, and the cohesion and the bonding strength of the waterborne polyurethane adhesive can be improved. In addition, hydroxyl in the mono-amine chain extender diethanolamine and phenolic hydroxyl in the sodium lignosulfonate can further react with the polyisocyanate curing agent to form a cross-linked network structure, so that the hydrolysis resistance of the waterborne polyurethane adhesive is improved.

(3) The sodium lignosulfonate amine can provide partial sulfonate, reduce the content of sodium sulfamate, react with isocyanate for crosslinking, protect ester bonds from hydrolysis and improve the bonding performance and hydrolysis resistance of the waterborne polyurethane adhesive.

(4) The invention has the advantages of convenient operation, simple process, safety and no toxicity.

Detailed Description

In order to make the present invention more comprehensible, the technical solutions of the present invention are further described below with reference to specific embodiments, but the present invention is not limited thereto.

Example 1

Firstly, dissolving 20 g of sodium lignosulfonate, 12.24 g of diethylenetriamine and 4.8 g of formaldehyde solution (36 wt%) in 100 g of deionized water, adding NaOH solution (10 wt%) to adjust the pH value to 10-12, and reacting for 5 hours at 70 ℃; then cooling the mixture to room temperature, slowly pouring the mixture into a large amount of absolute ethyl alcohol to precipitate a product, centrifugally separating the product, washing the product for 3 times by using the absolute ethyl alcohol, and then carrying out vacuum drying at 50 ℃ for 24 hours to obtain sodium lignosulfonate amine;

secondly, 87 g of polybutylene adipate diol is dehydrated at 110 ℃, added into a reactor, and then 4.4 g of isophorone diisocyanate, 6.7 g of hexamethylene diisocyanate, 0.03 g of 1, 4-butanediol and 0.02 g of dibutyltin dilaurate are added into the reactor and reacted for 3 hours at 80 ℃ so that the residual NCO groups account for less than 1.34 wt% of the prepolymer; then adding 60 g of acetone for reducing viscosity, dissolving 0.375 g of sodium lignosulphonate, 1.1 g of ethylenediamine ethanesulfonic acid sodium and 0.54 g of diethanolamine in 5g of deionized water, adding the mixture into a reactor for chain extension reaction, and reacting at 50 ℃ for 0.5 h to obtain a polyurethane prepolymer;

step three, adding 110 g of deionized water into 165g of polyurethane prepolymer, carrying out high-speed shearing dispersion for 0.5 h at 25 ℃, and then vacuumizing to remove acetone to obtain a water-based polyurethane emulsion;

and fourthly, adding 0.01 g of defoaming agent, 0.03 g of thickening agent and 0.6 g of curing agent into 40 g of aqueous polyurethane emulsion and uniformly mixing to obtain the aqueous polyurethane adhesive.

Comparative example 1

The first step, 87 g of poly butanediol adipate diol is dehydrated at 110 ℃ and then added into a reactor, 4.4 g of isophorone diisocyanate, 6.7 g of hexamethylene diisocyanate, 0.03 g of 1, 4-butanediol and 0.02 g of dibutyltin dilaurate are added into the reactor and reacted at 80 ℃ for 3 hours, so that the residual NCO groups account for less than 1.34 wt% of the mass of the prepolymer; then adding 60 g of acetone for reducing viscosity, dissolving 1.2 g of ethylenediamine ethanesulfonic acid sodium salt and 0.2 g of ethylenediamine in 5g of deionized water, adding the mixture into a reactor for chain extension reaction, and reacting at 50 ℃ for 0.5 h to obtain a polyurethane prepolymer;

secondly, adding 110 g of deionized water into 165g of polyurethane prepolymer, carrying out high-speed shearing dispersion for 0.5 h at 25 ℃, and then vacuumizing to remove acetone to obtain a water-based polyurethane emulsion;

and thirdly, adding 0.01 g of defoaming agent, 0.03 g of thickening agent and 0.6 g of curing agent into 40 g of aqueous polyurethane emulsion and uniformly mixing to obtain the aqueous polyurethane adhesive.

Comparative example 2

Step one, preparing sodium lignosulfonate amine according to step one in example 1;

secondly, 87 g of polybutylene adipate diol is dehydrated at 110 ℃, added into a reactor, and then 4.4 g of isophorone diisocyanate, 6.7 g of hexamethylene diisocyanate, 0.03 g of 1, 4-butanediol and 0.02 g of dibutyltin dilaurate are added into the reactor and reacted for 3 hours at 80 ℃ so that the residual NCO groups account for less than 1.34 wt% of the prepolymer; then adding 60 g of acetone for reducing viscosity, dissolving 1.2 g of ethylenediamine ethanesulfonic acid sodium salt and 0.2 g of ethylenediamine in 5g of deionized water, adding the mixture into a reactor for chain extension reaction, and reacting at 50 ℃ for 0.5 h to obtain a polyurethane prepolymer;

dissolving 1.5 g of sodium lignosulfonate amine in 110 g of deionized water, adding 165g of polyurethane prepolymer, shearing and dispersing at a high speed at 25 ℃ for 0.5 h, and vacuumizing to remove acetone to obtain aqueous polyurethane emulsion;

Example 2

secondly, 87 g of polycarbonate polyol is dehydrated at 110 ℃, added into a reactor, and then 4.4 g of isophorone diisocyanate, 6.7 g of hexamethylene diisocyanate, 0.03 g of 1, 4-butanediol and 0.02 g of dibutyltin dilaurate are added into the reactor and reacted for 3 hours at 80 ℃ to ensure that the residual NCO groups account for less than 1.34 wt% of the prepolymer; then adding 60 g of acetone for reducing viscosity, dissolving 0.75 g of sodium lignosulphonate, 1.0 g of ethylenediamine ethanesulfonic acid sodium and 0.36 g of diethanolamine in 5g of deionized water, adding the mixture into a reactor for chain extension reaction, and reacting at 50 ℃ for 0.5 h to obtain a polyurethane prepolymer;

Example 3

secondly, 87 g of polybutylene adipate diol is dehydrated at 110 ℃, added into a reactor, and then 4.4 g of isophorone diisocyanate, 6.7 g of hexamethylene diisocyanate, 0.03 g of 1, 4-butanediol and 0.02 g of dibutyltin dilaurate are added into the reactor and reacted for 3 hours at 80 ℃ so that the residual NCO groups account for less than 1.34 wt% of the prepolymer; then adding 60 g of acetone for viscosity reduction, dissolving 1.13 g of sodium lignosulphonate, 1.1 g of ethylenediamine ethanesulfonic acid sodium and 0.18 g of diethanolamine in 5g of deionized water, adding the mixture into a reactor for chain extension reaction, and reacting at 50 ℃ for 0.5 h to obtain a polyurethane prepolymer;

Example 4

secondly, 87 g of polybutylene adipate diol is dehydrated at 110 ℃, added into a reactor, and then 4.4 g of isophorone diisocyanate, 6.7 g of hexamethylene diisocyanate, 0.03 g of 1, 4-butanediol and 0.02 g of dibutyltin dilaurate are added into the reactor and reacted for 3 hours at 80 ℃ so that the residual NCO groups account for less than 1.34 wt% of the prepolymer; then adding 60 g of acetone for reducing viscosity, dissolving 0.75 g of sodium lignosulphonate, 1.1 g of ethylenediamine ethanesulfonic acid sodium and 0.36 g of diethanolamine in 5g of deionized water, adding the mixture into a reactor for chain extension reaction, and reacting at 50 ℃ for 0.5 h to obtain a polyurethane prepolymer;

Performance testing

The solid content of the aqueous polyurethane emulsion prepared in the above examples and comparative examples is controlled to be about 46%, and the mechanical properties of the film formed from the aqueous polyurethane emulsion, the adhesive properties of the aqueous polyurethane adhesive and the hydrolysis resistance are tested, and the results are shown in table 1.

1. The storage stability of the aqueous polyurethane emulsion was evaluated by a simulated centrifugal sedimentation experiment. After the test, if there is no flocculation or precipitation in the aqueous polyurethane emulsion, it is considered that the aqueous polyurethane emulsion can be stably stored for more than 6 months.

2. The mechanical properties of the waterborne polyurethane film are tested. The aqueous polyurethane film was punched into dumbbell-shaped test specimens having a length of about 20 mm, a width of about 4 mm and a thickness of between 0.4 and 0.8 mm. Each sample was stretched at a speed of 200 mm/min and five measurements were averaged.

3. The adhesion property was evaluated by measuring the T-peel strength of the styrene-butadiene rubber joint/aqueous polyurethane adhesive/styrene-butadiene rubber joint.

4. The hydrolysis resistance was evaluated as follows:

placing the prepared sample joint of the waterborne polyurethane adhesive in a constant temperature and humidity box for carrying out damp and heat treatment, firstly adjusting for 48 hours under the conditions of 23 ℃ and 50% of relative humidity, then placing the sample in a constant temperature and humidity box with 70 ℃ and 95% of relative humidity for 24 hours, then taking out, finally adjusting for 24 hours under the conditions of 23% of humidity and 50% of relative humidity, and then carrying out T peel test according to GB/T532 regulations to evaluate the hydrolysis resistance of the waterborne polyurethane adhesive.

TABLE 1 Properties of the waterborne polyurethanes

As can be seen from the above results, it was confirmed that,

as can be seen from Table 1, compared with the aqueous polyurethane prepared by adopting the traditional diamine chain extension in the comparative example 1, the aqueous polyurethane prepared by adding the sodium lignosulfonate amine can increase the mechanical strength and the bonding strength of the aqueous polyurethane adhesive and can reduce the using amount of part of ethylene diamine ethyl sodium sulfonate. The hydrolysis resistance peel strength of the aqueous polyurethane modified by the sodium lignosulfonate amine is better, even better than the final adhesion strength, because phenolic hydroxyl in the sodium lignosulfonate amine and hydroxyl in the monoamine chain extender diethanol amine can further react with a polyisocyanate curing agent under the damp-heat resistant environment to form a cross-linked network structure and hinder the water permeation, which is beneficial to improving the hydrolysis resistance of the aqueous polyurethane adhesive. Therefore, the sulfonic acid type aqueous polyurethane adhesive with good stability and high solid content can be obtained by introducing the sodium lignosulfonate amine for preparation, and the comprehensive performance of the obtained aqueous polyurethane adhesive is excellent.

Compared with the method of adding sodium lignosulfonate amine in the third step of shearing and dispersing in the comparative example 2, the method for preparing the aqueous polyurethane adhesive has the advantages of better stability and more excellent adhesive property and hydrolysis resistance. The main reason is that the sodium lignosulfonate amine participates in a chain extension reaction when synthesizing the prepolymer, and the sodium lignosulfonate can be wrapped in a branched polyurethane molecular chain, so that the compatibility of the sodium lignosulfonate and the waterborne polyurethane is better.

The comparison of the examples shows that the polybutylene adipate glycol is used as the macrodiol, so that the compatibility of polyurethane and sodium lignosulfonate amine is improved, the crystallinity of the waterborne polyurethane can be improved, and various performances of the waterborne polyurethane adhesive are improved.

The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.

Claims

1. The preparation method of the sulfonic acid type waterborne polyurethane adhesive is characterized by comprising the following steps:

(1) dissolving 20 parts by mass of sodium lignosulfonate, 10-16 parts by mass of diethylenetriamine and 4-6 parts by mass of 36 wt% formaldehyde solution in 100 parts by mass of deionized water, adding 10 wt% NaOH solution to adjust the pH value to 10-12, and reacting at 60-80 ℃ for 4-6 h; then cooling the mixture to room temperature, slowly pouring the mixture into a large amount of absolute ethyl alcohol to precipitate a product, centrifugally separating the product, washing the product for 3 times by using the absolute ethyl alcohol, and then carrying out vacuum drying at 50 ℃ for 24 hours to obtain sodium lignosulfonate amine;

(2) adding 87 mass parts of polyester polyol or polyether polyol into a reactor after dehydration at the temperature of 100-120 ℃, adding 10-12 mass parts of diisocyanate, 0.03 mass part of micromolecular polyol chain extender and 0.01-0.02 mass part of organic metal catalyst, and reacting for 2-4 hours at the temperature of 70-85 ℃ until the residual NCO groups account for less than 0.96-1.72 percent of the mass of the prepolymer; then adding 30-80 parts by mass of acetone for viscosity reduction, adding a mixed solution formed by dissolving 0.05-3 parts by mass of sodium lignosulfonate, 0.5-2 parts by mass of sulfonate hydrophilic chain extender and 0.1-1 part by mass of monoamine chain extender in 5 parts by mass of deionized water, and carrying out chain extension reaction at 40-60 ℃ for 0.5-1 h to obtain a polyurethane prepolymer;

2. The method for preparing a sulfonic acid type aqueous polyurethane adhesive according to claim 1, wherein: in the step (2), the polyester polyol is any one or more of polycaprolactone polyol, polycarbonate polyol and polyester adipate polyol, and the polyether polyol is any one or more of polytetrahydrofuran polyol, ethoxy-terminated polymer glycol and propylene oxide polyether polyol.

3. The method for preparing a sulfonic acid type aqueous polyurethane adhesive according to claim 1, wherein: the diisocyanate in the step (2) is any one or more of isophorone diisocyanate, hexamethylene diisocyanate, methylcyclohexyl isocyanate and toluene diisocyanate.

4. The method for preparing a sulfonic acid type aqueous polyurethane adhesive according to claim 1, wherein: in the step (2), the micromolecular polyalcohol chain extender is any one or more of ethylene glycol, 1, 4-butanediol, 1, 6-hexanediol, neopentyl glycol and 1, 5-pentanediol.

5. The method for preparing a sulfonic acid type aqueous polyurethane adhesive according to claim 1, wherein: in the step (2), the organic metal catalyst is any one or more of organic bismuth, organic tin, organic zirconium and bismuth-zinc alloy catalyst.

6. The method for preparing a sulfonic acid type aqueous polyurethane adhesive according to claim 1, wherein: the sulfonate type hydrophilic chain extender in the step (2) is any one or more of ethylenediamine ethyl sodium sulfonate and ethylenediamine propyl sodium sulfonate.

7. The method of preparing the sulfonic acid type aqueous polyurethane adhesive according to claim 1, wherein: in the step (2), the monoamine chain extender is one or more of methylamine, ethylamine, propylamine, n-butylamine, dibutylamine, 2-aminobutane, 1-aminopentane, 2-aminopentane, 1-amino-2-propanol, 3-amino-1-propanol, ethanolamine and diethanolamine.

8. The method for preparing a sulfonic acid type aqueous polyurethane adhesive according to claim 1, wherein: the solid content of the aqueous polyurethane emulsion obtained in the step (3) is 30-60 wt%.