CN115340656B - Modified isocyanate with water dispersion and protection functions and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to modified isocyanate with water dispersion and protection functions and a preparation method thereof. The preparation method of the modified isocyanate with the water dispersion and protection functions comprises the following steps: according to the mass percentage, 68-82% of isocyanate, 8-10% of organic solvent and 10-22% of amphiphilic molecular chain compound are reacted for 4-8 hours at the temperature of 80-90 ℃ to obtain the modified polyurethane resin; wherein the amphiphilic molecular chain compound is polyethylene glycol monomethyl ether-salicylic acid compound. The isocyanate and the amphiphilic molecular chain are used as the main agents, and the prepared modified isocyanate has a self-emulsifying function, so that the dispersibility of the isocyanate in a water environment can be improved; meanwhile, the isocyanate has a protection function, can improve the stability of the isocyanate when the isocyanate contains active hydrogen (water), prolongs the application period of the isocyanate in water environment, and greatly expands the application range of the isocyanate.

Description

A modified isocyanate with both water dispersion and protection functions and its preparation method

technical field

The invention belongs to the technical field of polymer materials, and in particular relates to a modified isocyanate with water dispersion and protection functions and a preparation method thereof.

Background technique

Isocyanate is widely used in coatings, adhesives, fields such as medicine, agriculture and composite materials. However, due to the high chemical activity of isocyanate, its poor stability in water and poor water dispersibility, its application in the above fields is greatly limited.

In the prior art, the reaction between isocyanate and polyethylene glycol monomethyl ether is usually used to improve the hydrophilicity of isocyanate, thereby improving the dispersibility of isocyanate in water. However, although the hydrophilicity of the obtained isocyanate prepared by the existing method is improved, as the degree of water dispersion increases, the side reaction between the active groups in the isocyanate and water will also intensify, so that the active groups of the isocyanate are consumed and the isocyanate is reduced. active.

Contents of the invention

In view of this, the purpose of the present invention is to provide a kind of preparation method of the modified isocyanate that has water dispersion and protection function concurrently, it can improve the water dispersibility of isocyanate, can effectively protect isocyanate active group simultaneously, improve the isocyanate in water. stability.

The purpose of the present invention is also to provide a modified isocyanate with both water dispersion and protection functions, which has both excellent water dispersion and stability.

To achieve the above object, the technical solution adopted in the present invention is:

A method for preparing a modified isocyanate with both water dispersion and protection functions, comprising the following steps: in terms of mass percentage, 68-82% of isocyanate, 8-10% of organic solvent, 10-22% of amphiphilic The molecular chain compound is obtained by reacting at 80-90° C. for 4-8 hours; wherein, the amphiphilic molecular chain compound is polyethylene glycol monomethyl ether-salicylic acid complex.

In the present invention, by carrying out blending reaction of isocyanate, organic solvent, and amphiphilic molecular chain compound (polyethylene glycol monomethyl ether-salicylic acid complex) at a certain temperature, a kind of water dispersion and protection function can be obtained. modified isocyanates. Among them, in the modified isocyanate, the isocyanate group is located in the central part, directly grafted with salicylic acid, and then the salicylic acid is connected with polyethylene glycol monomethyl ether. Among them, the introduced salicylic acid group can effectively prevent water from approaching the isocyanate in the center, play an effective protective role and increase the stability of isocyanate in water, and the polyethylene glycol monomethyl ether in the outer layer has a good Hydrophilicity can effectively improve the water solubility of isocyanate, so the isocyanate prepared by the present invention has both excellent dispersion and stability in water, which greatly meets the application requirements of isocyanate in water environment.

As the isocyanate, common isocyanate species in the art can be used. Preferably, the isocyanate is polymethylene polyphenyl polyisocyanate, isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate one or several.

The present invention does not specifically limit the type of organic solvent, as long as it can dissolve and adjust the viscosity of the corresponding isocyanate, and does not contain active hydrogen that reacts with isocyanate. Preferably, the organic solvent is one or more of methylene chloride, chloroform, toluene, ethylene dichloride, ethyl acetate, and butyl acetate, more preferably methylene chloride.

Preferably, the preparation process of the polyethylene glycol monomethyl ether-salicylic acid complex comprises the following steps:

(1) Dissolve salicylic acid in N,N-dimethylformamide, then lower the temperature to -10°C~10°C, add acid chloride reagent dropwise while stirring, and react at 50~60°C for 0.5~1.5 h;

(2) Add polyethylene glycol monomethyl ether into the system after the reaction in step (1), continue to react for 1.5-2.5 hours under the protection of nitrogen, and then purify to obtain the product.

The present invention adopts the above method to prepare the obtained polyethylene glycol monomethyl ether-salicylic acid complex, which is an amphiphilic molecular chain compound. The above-mentioned amphiphilic molecular weight compound is the reaction between the hydroxyl group of polyethylene glycol monomethyl ether (MPEG) and the carboxyl group of salicylic acid (SA) to generate the desired amphiphilic molecular chain structure. Among them, the salicylic acid end is a hydrophobic end, and the polyethylene glycol monomethyl ether end is a hydrophilic end. Through the above reaction process, the occurrence of side reactions can be effectively avoided, so that the salicylic acid at the hydrophobic end retains active hydroxyl groups, and subsequent React with isocyanate to effectively graft onto isocyanate; at the same time, through the above reaction process, the active group hydroxyl in the polyethylene glycol monomethyl ether at the hydrophilic end is consumed, thus losing the activity that can react with isocyanate group, which further improves the structural stability of the modified isocyanate.

Since salicylic acid and polyethylene glycol monomethyl ether have more than one active group, there are many types of side reactions, and in order to reduce the occurrence of side reactions, reduce the residue of by-products, and improve reaction efficiency, the obtained What needs is the product that the hydroxyl group of polyethylene glycol monomethyl ether (MPEG) and the carboxyl reaction of salicylic acid (SA), the present invention adds acid chloride reagent earlier and makes salicylic acid generation acid chloride reaction, and then reacts with polyethylene glycol Alcohol monomethyl ether reaction, preferably, the acid chloride reagent is one or more of thionyl chloride, phosphorus trichloride, phosphorus pentachloride.

In order to ensure the modification effect of the amphiphilic molecular chain on the water dispersibility and water stability of the isocyanate, as a further preferred solution, the molecular weight of the polyethylene glycol monomethyl ether is 750-1000.

In order to improve the product conversion effect of each step reaction, preferably, the molar ratio of salicylic acid, acyl chloride reagent, and polyethylene glycol monomethyl ether is 1:(1-1.2):(1-1.2).

Preferably, the purification specifically includes: extracting and purifying the product by solvent extraction using dichloromethane as a solvent.

The modified isocyanate having both water dispersion and protection functions of the present invention is prepared by the above-mentioned preparation method.

The beneficial effects of the present invention are:

The preparation method of the modified isocyanate with both water dispersion and protection functions of the present invention uses isocyanate and amphiphilic molecular chain as the main agent, and the prepared isocyanate has a self-emulsifying function, which can improve the dispersibility of the isocyanate in the water environment; at the same time It also has protective function, can improve the stability of isocyanate when it contains active hydrogen (water), and prolong the service life of isocyanate in water environment.

The modified isocyanate with both water dispersion and protection functions of the present invention can be dispersed and emulsified in a water environment without additional emulsifiers, and the self-emulsifying water-dispersible isocyanate improves hydrophilicity through polar molecular chains, so it is also Unaffected by ions, it can improve the stability of isocyanate dispersion or emulsion.

The modified isocyanate prepared by the present invention, which has both water dispersion and protection functions, has higher activity. Experiments show that its active -NCO group still has a higher active group content after being stored in water for up to 8 hours. , convenient storage and other advantages.

Description of drawings

Fig. 1 is the Fourier transform infrared spectrogram of the modified isocyanate having both water dispersion and protection functions prepared in Example 1 of the present invention;

Fig. 2 is the particle size and particle size distribution diagram of the emulsion corresponding to the modified isocyanate having both water dispersion and protection functions prepared in Example 1 of the present invention;

Fig. 3 is the physical picture of the emulsion corresponding to the modified isocyanate having both water dispersion and protection functions prepared in Example 1 of the present invention at different time periods;

Fig. 4 shows the change of isocyanate activity content in different time periods of the emulsion corresponding to the modified isocyanate having both water dispersion and protection functions prepared in Example 1 of the present invention.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with specific embodiments, but this does not constitute a limitation to the present invention. In the following examples, the reagents involved are commercially available conventional reagents unless otherwise specified; the test methods involved are conventional methods unless otherwise specified. In the following examples, in the polymethylene polyphenyl polyisocyanate used, the active group-NCO content is 30%; in the isophorone diisocyanate raw material, the active group-NCO content is 37%; In the following examples, the polyethylene glycol monomethyl ether used is MPEG-750 and MPEG-1000 with molecular weights of 750 and 1000, respectively.

Example 1

The modified isocyanate having both water dispersion and protection functions of this embodiment is prepared by a method comprising the following steps:

In terms of mass percentage, 82% of isocyanate and 8% of organic solvent are added to a dry reactor, heated in a constant temperature oil bath, and then 10% of amphiphilic molecular chain compounds are added dropwise to the reactor, and the oil bath is 1 To 85 ° C, after 4 hours of reaction, the end, that is.

Wherein, the isocyanate is polymethylene polyphenyl polyisocyanate (PAPI); the organic solvent is methylene chloride; SA).

The specific preparation method of the amphiphilic molecular chain compound MPEG-SA of the present embodiment is as follows:

Add salicylic acid and N,N-dimethylformamide into the dry reaction kettle, put them into an ice-water bath after dissolving, and add thionyl chloride dropwise while stirring (the molar ratio of salicylic acid to thionyl chloride is 1 :1.1), within 30min, the water bath temperature was raised to 55°C, and the acid chloride was reacted for 1 hour; after the acid chloride, MPEG-750 (salicylic acid, MPEG-750 molar ratio 1:1.1) was added dropwise to the reaction In the still, under the protection of nitrogen, the reaction was continued for 2 h; the product was extracted and purified with dichloromethane to obtain MPEG-SA.

Example 2

The modified isocyanate having both water dispersion and protection functions of this embodiment is prepared by a method comprising the following steps:

In terms of mass percentage, 76% of isocyanate and 10% of organic solvent are added to a dry reactor, heated in a constant temperature oil bath, and then 14% of amphiphilic molecular chain compounds are added dropwise to the reactor, and the oil bath is 1 To 85 ° C, after 4 hours of reaction, the end, that is.

Wherein, the isocyanate is polymethylene polyphenyl polyisocyanate (PAPI); the organic solvent is methylene chloride; SA).

The specific preparation method of the amphiphilic molecular chain compound MPEG-SA is as follows:

Add salicylic acid and N,N-dimethylformamide into the dry reaction kettle, put them into an ice-water bath after dissolving, and add thionyl chloride dropwise while stirring (the molar ratio of salicylic acid to thionyl chloride is 1 :1.1), within 30min, the water bath temperature was raised to 55°C, and the acid chloride was reacted for 1 hour; after the acid chloride, MPEG-750 (salicylic acid, MPEG-750 molar ratio 1:1.1) was added dropwise to the reaction In the still, under the protection of nitrogen, the reaction was continued for 2 h; the product was extracted and purified with dichloromethane to obtain MPEG-SA.

Example 3

The modified isocyanate having both water dispersion and protection functions of this embodiment is prepared by a method comprising the following steps:

In terms of mass percentage, 76% of isocyanate and 10% of organic solvent are added to a dry reactor, heated in a constant temperature oil bath, and then 14% of amphiphilic molecular chain compounds are added dropwise to the reactor, and the oil bath is 1 To 85 ° C, after 8 hours of reaction, the end, that is.

Wherein, the isocyanate is isophorone diisocyanate (IPDI); the organic solvent is methylene chloride; the amphiphilic molecular chain compound is polyethylene glycol monomethyl ether 750-salicylic acid (marked as MPEG-SA).

The specific preparation method of the amphiphilic molecular chain compound MPEG-SA of the present embodiment is as follows:

Add salicylic acid and N,N-dimethylformamide into the dry reaction kettle, put them into an ice-water bath after dissolving, and add thionyl chloride dropwise while stirring (the molar ratio of salicylic acid to thionyl chloride is 1 :1.1), within 30min, the water bath temperature was raised to 55°C, and the acid chloride was reacted for 1 hour; after the acid chloride, MPEG-750 (salicylic acid, MPEG-750 molar ratio 1:1.1) was added dropwise to the reaction In the still, under the protection of nitrogen, the reaction was continued for 2 h; the product was extracted and purified with dichloromethane to obtain MPEG-SA.

Example 4

The modified isocyanate having both water dispersion and protection functions of this embodiment is prepared by a method comprising the following steps:

In terms of mass percentage, 68% of isocyanate and 10% of organic solvent are added to a dry reactor, heated in a constant temperature oil bath, and then 22% of amphiphilic molecular chain compounds are added dropwise to the reactor, and the oil bath is 1 To 85 ° C, after 8 hours of reaction, the end, that is.

Wherein, the isocyanate is isophorone diisocyanate (IPDI); the organic solvent is methylene chloride; the amphiphilic molecular chain compound is polyethylene glycol monomethyl ether 1000-salicylic acid complex (marked as MPEG-SA).

The specific preparation method of the amphiphilic molecular chain compound MPEG-SA of the present embodiment is as follows:

Add salicylic acid and N,N-dimethylformamide into the dry reaction kettle, put them into an ice-water bath after dissolving, and add thionyl chloride dropwise while stirring (the molar ratio of salicylic acid to thionyl chloride is 1 :1.1), within 30min, the water bath temperature was raised to 55°C, and the acid chloride was reacted for 1 hour; after the acid chloride reaction, MPEG-1000 (salicylic acid, MPEG-1000 molar ratio 1:1.1) was added to the reaction In the still, under the protection of nitrogen, the reaction was continued for 2 h; the product was extracted and purified with dichloromethane to obtain MPEG-SA.

Comparative example 1

The modified isocyanate of this comparative example, the preparation method that adopts comprises the following steps: by mass percentage, 82% isocyanate, 8% organic solvent are added in the reaction kettle of drying, constant temperature oil bath heating, then 10% Add polyethylene glycol monomethyl ether 750 dropwise into the reactor, raise the oil bath to 85°C, and finish the reaction after 4 hours to obtain the product.

Comparative example 2

The preparation method of the modified isocyanate of this comparative example is basically the same as that of Example 1, the difference being that the involved amphiphilic molecular chain compound is prepared by using tartaric acid instead of salicylic acid.

Comparative example 3

The preparation method of the modified isocyanate of this comparative example is basically the same as that of Example 1, the difference being that the involved amphiphilic molecular chain compound is prepared by using malic acid instead of salicylic acid.

Comparative example 4

The preparation method of the modified isocyanate of this comparative example is basically the same as that of Example 1, the difference being that the involved amphiphilic molecular chain compound is prepared by using thioglycolic acid instead of salicylic acid.

Comparative example 5

The preparation method of the modified isocyanate of this comparative example is basically the same as that of Example 1, the difference being that the involved amphiphilic molecular chain compound is prepared by using tyrosine instead of salicylic acid.

Test example 1

The following test examples characterize and test the structure and appearance stability of the modified isocyanate prepared in Example 1 of the present invention with both water dispersion and protection functions.

The MPEG-SA involved in Example 1 of the present invention was tested by Fourier transform infrared spectroscopy, and the results are shown in FIG. 1 .

As can be seen from Figure 1, in the infrared spectrum curve of salicylic acid (SA), there is a characteristic peak of -OH near 3236cm ^-1 , and a characteristic peak of phenolic hydroxyl at 1210cm ^-1 ; The characteristic absorption peak of (Ph) linked carboxyl group (Ph-COOH) moves to the lower wave number, appearing at 1656cm ^-1 ; 1298cm ^-1 is characteristic of carboxylic acid or carboxylic acid ester (Ph-COO-) linked with aromatic Absorption peak; 758cm ^-1 is the characteristic peak of adjacent disubstituted (carboxyl, hydroxyl) benzene rings. In the infrared spectrum curve of polyethylene glycol monomethyl ether ⁽ MPEG ⁾ , the characteristic peak of alcoholic hydroxyl group (R-OH) is around _3453cm ^-1 ; _3. -O- characteristic absorption peak. In the infrared spectrum curve of MPEG-SA, there is no R-OH characteristic peak near 3453cm ^-1 and Ph-COOH characteristic peak at 1656cm ^-1 , but the phenolic hydroxyl Ph-OH characteristic peak at 1210cm ^-1 , 2850cm ^{-1 1.} The characteristic absorption peaks of -CH ₂ - and -O- at 1106cm ^-1 , the characteristic absorption peak of Ph-COO- at 1298cm ^-1 and the characteristic peaks of adjacent disubstituted benzene rings at 758cm ^-1 are all retained; except In addition, the characteristic absorption peak of the ester bond (Ph-COOR) connected with the aromatic ring at 1729cm ^-1 and the characteristic absorption peak of the carbonyl bond (Ph-CO-) connected with the aromatic ring at 1676cm ^-1 appeared. This shows that there is no R-OH and Ph-COOH in the MPEG-SA molecule synthesized by the present invention, and there is newly generated Ph-COOR, which shows that SA and MPEG have an esterification reaction, and the required amphiphilic molecular chain has been obtained. compound.

The particle size and appearance stability of the emulsion prepared from the modified isocyanate obtained in Example 1 of the present invention were further tested. During the test, the modified isocyanate and water were mixed according to the mass ratio of 1:9, and the modified isocyanate emulsion was obtained after mixing evenly. Particle size test process: take 1mL emulsion and dilute it 100 times, and use a laser particle size analyzer to test its particle size and distribution. The emulsion appearance stability test is to emulsify the modified isocyanate to prepare the emulsion, and then take pictures every hour to compare the emulsion stability. The results are shown in Figures 2 and 3.

It can be seen from Figure 2 that the emulsion droplet size of the modified isocyanate emulsion prepared by the present invention is about 50 μm, and the particle size distribution presents a parabolic shape, and the distribution is relatively narrow, indicating that the modified isocyanate of the present invention can be uniformly dispersed in water.

It can be seen from Figure 3 that the modified isocyanate prepared by the present invention has a uniform milky white dispersion after water dispersion and emulsification, and there is no obvious layering phenomenon after long-term storage, and it has good appearance stability.

Test example 2

The water stability of the modified isocyanate in Example 1 and Comparative Example 1 of the present invention was tested, and the results are shown in FIG. 4 and Table 1. The stability test process is as follows: the modified isocyanate sample is prepared by the method of Test Example 1 to obtain an emulsion, and then the prepared emulsion is uniformly sampled (about 2g) every 1 hour, and the modified isocyanate is tested by di-n-butylamine chemical analysis titration method Active group (-NCO) content in the sample (calculated as isocyanate).

The stability test result of table 1 modified isocyanate

It can be seen from Fig. 1 and Table 1 that the modified isocyanate prepared by the present invention, after being made into an emulsion and placed for 8 hours, its active -NCO group content can still be maintained at about 61.4% of the initial content, while the modified isocyanate prepared by the existing conventional method Non-toxic isocyanate, the active group loses quickly, and the active ingredient content can only retain 13.8%. It can be seen that the modified isocyanate prepared by the preparation method of the present invention can effectively reduce the influence of water on the active component of isocyanate and improve its stability in the water environment.

The water dispersion and water stability of the modified isocyanates obtained in Examples 1-4 of the present invention and Comparative Examples 1-5 were further compared and tested, and the results are shown in Table 2. Among them, the water dispersibility test process is: mix the prepared modified isocyanate with 9 times the mass of water (shake well for 1 minute), and then observe whether the emulsion has delamination after standing for 6 hours. The stability test process is: the modified isocyanate is emulsified to prepare an emulsion, and then the configured emulsion is placed for 6 hours and evenly sampled (about 2g), and the active group of the modified isocyanate is tested by di-n-butylamine chemical analysis titration method ( -NCO) content (calculated as isocyanate).

Table 2 Dispersion properties and stability of different modified isocyanate materials

serial number water dispersion Active group content, % Example 1 Unlayered 16.68 Example 2 Unlayered 13.68 Example 3 Unlayered 23.31 Example 4 Unlayered 19.20 Comparative example 1 Unlayered 4.09 Comparative example 2 obvious stratification layered, undetectable Comparative example 3 obvious stratification layered, undetectable Comparative example 4 obvious stratification layered, undetectable Comparative example 5 slightly layered layered, undetectable

As can be seen from Table 2, the use of polyfunctional hydroxy acids (tartaric acid, malic acid) or mercapto- and amino-containing acids (thioglycolic acid, tyrosine) instead of salicylic acid cannot be effectively prepared to obtain a good water dispersion. Amphiphilic molecular chains with high performance and water stability, so it is impossible to successfully prepare a uniform modified isocyanate emulsion. Due to the layering of the emulsion, it is also impossible to sample uniformly, so that the content of active groups cannot be accurately determined. It can be seen that the present invention has special requirements for hydroxyacids, which must contain a carboxyl group and a hydroxyl group in its molecule, and it needs to have specific structural restrictions, so that it is difficult to cause intramolecular or intermolecular friction in the process of preparing amphiphilic molecular chains. Chain extension reactions such as esterification or amidation.

In summary, the modified isocyanate prepared by the present invention, while achieving uniform dispersion, the active -NCO group still has a high active group content after being stored in water for up to 8 hours, has good stability, and is basically odorless. It has the advantages of convenient use, transportation and storage.

Claims (8)

1. The preparation method of the modified isocyanate with the functions of water dispersion and protection is characterized by comprising the following steps: according to the mass percentage, 68-82% of isocyanate, 8-10% of organic solvent and 10-22% of amphiphilic molecular chain compound are reacted for 4-8 hours at the temperature of 80-90 ℃ to obtain the modified polyurethane resin;

wherein the amphiphilic molecular chain compound is polyethylene glycol monomethyl ether-salicylic acid compound; the polyethylene glycol monomethyl ether-salicylic acid compound is prepared by esterification reaction of polyethylene glycol monomethyl ether and salicylic acid.

2. The method for preparing a modified isocyanate with both water dispersion and protection functions according to claim 1, wherein the isocyanate is one or more of polymethylene polyphenyl polyisocyanate, isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate and hexamethylene diisocyanate.

3. The method for preparing modified isocyanate with water dispersion and protection functions according to claim 1, wherein the organic solvent is one or more of dichloromethane, chloroform, toluene, dichloroethane, ethyl acetate and butyl acetate.

4. The method for preparing the modified isocyanate with the water dispersion and protection functions according to claim 1, wherein the preparation process of the polyethylene glycol monomethyl ether-salicylic acid compound comprises the following steps:

(1) Dissolving salicylic acid in N, N-dimethylformamide, cooling to-10 ℃ to 10 ℃, dropwise adding an acyl chloride reagent while stirring, and reacting for 0.5-1.5 h at 50-60 ℃;

(2) Adding polyethylene glycol monomethyl ether into the system after the reaction in the step (1), continuing to react for 1.5-2.5 h under the protection of nitrogen, and then purifying to obtain the product.

5. The method for preparing modified isocyanate with water dispersion and protection functions according to claim 4, wherein the acyl chloride reagent is one or more of thionyl chloride, phosphorus trichloride and phosphorus pentachloride.

6. The method for preparing modified isocyanate with water dispersion and protection functions according to claim 4, wherein the molecular weight of polyethylene glycol monomethyl ether is 750-1000.

7. The method for preparing the modified isocyanate with water dispersion and protection functions according to any one of claims 4 to 6, wherein the molar ratio of salicylic acid, acyl chloride reagent and polyethylene glycol monomethyl ether is 1: (1 to 1.2): (1-1.2).

8. The modified isocyanate with the water dispersion and protection functions is characterized in that the modified isocyanate with the water dispersion and protection functions is prepared by the preparation method of the modified isocyanate with the water dispersion and protection functions according to any one of claims 1-7.

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