阅读说明：本技术 一种低色号高稳定性碳化二亚胺改性异氰酸酯的制备方法 (Preparation method of carbodiimide modified isocyanate with low color number and high stability ) 是由 陈盟 王文博 夏以禄 肖应鹏 朱梦雅 包金鹏 徐丹 张宏科 于 2020-11-17 设计创作，主要内容包括：本发明涉及一种低色号高稳定性碳化二亚胺改性异氰酸酯的制备方法。该方法包括以下步骤：S1：异氰酸酯单体进行碳化二亚胺化反应,得到含碳化二亚胺(CDI)和/或脲酮亚胺(UTI)基团反应液；S2：熟化反应减少反应液中CDI含量,控制CDI含量在0.5％-4.0％；S3：添加终止剂终止碳化二亚胺化反应。该方法制备的改性异氰酸酯具有常温液态、常温和高温存储稳定且低色号的特征。(The invention relates to a preparation method of carbodiimide modified isocyanate with low color number and high stability. The method comprises the following steps: s1: carrying out carbodiimide imidization on an isocyanate monomer to obtain a reaction solution containing Carbodiimide (CDI) and/or Uretonimine (UTI) groups; s2: the content of CDI in the reaction liquid is reduced by the curing reaction, and the content of CDI is controlled to be 0.5-4.0%; s3: the carbodiimidization reaction is terminated by adding a terminator. The modified isocyanate prepared by the method has the characteristics of normal-temperature liquid state, stable normal-temperature and high-temperature storage and low color number.)

1. A preparation method of carbodiimide modified isocyanate with low color number and high stability is characterized by comprising the following steps:

s1: carrying out carbodiimide imidization on an isocyanate monomer to obtain a reaction solution containing Carbodiimide (CDI) and/or Uretonimine (UTI) groups;

s2: the content of CDI in the reaction liquid is reduced through the curing reaction, and the content of CDI is controlled to be 0.5-4.0 percent, preferably 1.0-1.5 percent, based on the total mass of the reaction liquid;

s3: the carbodiimidization reaction is terminated by adding a terminator.

2. The method according to claim 1, wherein the isocyanate monomer in S1 is selected from one or more of aromatic diisocyanate, araliphatic diisocyanate and aliphatic diisocyanate, preferably aromatic diisocyanate, more preferably diphenylmethane diisocyanate.

3. The method according to claim 1 or 2, wherein a phospholane catalyst is added to S1, preferably wherein the catalyst is one or more of a phospholane catalyst, a phospholane oxo catalyst, a phosphole catalyst, and a phosphole oxo catalyst, more preferably 1-methyl-3-phosphole-1-oxide;

preferably, the catalyst is used in an amount of 1 to 5ppm, preferably 3 to 5ppm, based on the total weight of isocyanate monomer;

and/or the reaction temperature of S1 is 40-210 ℃, preferably 90-110 ℃.

4. The preparation method according to any one of claims 1 to 3, wherein S2 is added with acyl chloride to accelerate the curing speed;

preferably, the acid chloride is selected from one or more of methyl oxalyl chloride, ethyl oxalyl chloride and benzoyl chloride, preferably methyl oxalyl chloride;

preferably, the addition amount of the acyl chloride is 3-10ppm, preferably 3-5ppm, based on the total weight of the reaction liquid;

and/or the curing reaction temperature is 45-80 ℃, and the reaction time is 1-72 h, preferably 2-24 h.

5. The method according to any one of claims 1 to 4, wherein a terminator is added when the target CDI value is reached at S3;

and/or the terminating agent is one or more of strong acid, trifluoromethyl sulfonic anhydride, trifluoromethyl sulfonic acid, boric acid, hydrogen fluoride, and hydrogen chloride, preferably trifluoromethyl sulfonic anhydride;

preferably, the amount of the terminator is 1 to 10ppm, preferably 2.5 to 10ppm, more preferably 5 to 7.5ppm, based on the total weight of the reaction solution.

6. A carbodiimide modified isocyanate with low color number and high stability, which is obtained by the preparation method of any one of claims 1 to 5.

7. The modified isocyanate according to claim 6, wherein the modified isocyanate contains CDI and/or UTI groups;

preferably, the modified isocyanate contains 65-72 wt% of isocyanate monomer, 0.5-4.0 wt% of CDI, 10-20 wt% of UTI and 12-20 wt% of polymer;

preferably, the modified isocyanate color number is 5 to 30 APHA.

Technical Field

The invention belongs to the field of isocyanate, and particularly relates to a preparation method of carbodiimide modified isocyanate with low color number and high stability.

Background

Diisocyanate is one of the main raw materials of polyurethane, and is clear and transparent liquid when being melted. However, pure isocyanate is solid at room temperature and has poor stability during storage and transportation, which causes inconvenience in handling and storage. The carbodiimide modified isocyanate is liquid at normal temperature, is convenient to use and is favored by the majority of users. The carbodiimide modified isocyanate is characterized in that under the action of a high-efficiency catalyst, isocyanate is heated to carry out polycondensation reaction to form a modified product containing a carbodiimide structure, a carbodiimide group and the isocyanate can carry out addition reaction to form a uretonimine group, and the Carbodiimide (CDI) and Uretonimine (UTI) substances contained in the isocyanate can reduce the melting point of the isocyanate, so that the isocyanate is in a liquid state at normal temperature, forms a stable low-viscosity liquid to be convenient for transportation, and has certain storage stability.

The high-efficiency catalyst used in the isocyanate reaction is various, mainly is a high-efficiency catalyst of phospholane, and the catalyst can partially convert heated isocyanate into CDI/UTI derivatives under certain reaction conditions. The phospholene catalysts have a high catalytic activity in order to be able to activate carbodiimidization reactions under mild temperature conditions, but at room temperature the catalysts still have sufficient activity to affect the storage stability of the products containing free NCO groups, in which process NCO groups are continuously consumed, with CO being formed₂The product viscosity is increasing. And the higher the temperature is, the faster the reaction is, so that the product is transported in high-temperature weather, and the risk of drum is caused, and the product needs to be inactivated by other methods such as chemistry or physics, and the quality of the product is kept in a stable state.

In order to terminate the reaction, many attempts have been made, for example, by adding a catalyst poison as a terminator, specifically, CN1709863A added acid, CN1721395A added silylated acid, CN1789241A added esters of trifluoromethanesulfonic acid, ester compounds of inorganic acids, CN102718683A added acid anhydride compounds, and for example, CN101003496A terminated the reaction by controlling the conditions of the terminator addition.

EP515933A discloses isocyanate mixtures containing CDI/UTI groups prepared from phospholene catalysts, the termination catalyst activity being terminated at least with an equimolar, preferably 1-2 times molar amount of catalyst, for example trimethylsilyl trifluoromethanesulfonate (TMST). However, practice proves that the modified isocyanate prepared by the method has the problems of incomplete termination, poor storage stability and the like, particularly, in an environment with low outdoor temperature in winter, a water bath material is needed in the use process of the product, gas is generated in the material dissolving process, so that the pressure in a storage container is high, and the NCO of the product is obviously reduced and the viscosity is obviously increased.

This problem can be avoided by terminating the phospholane catalyst with a high molar equivalent ratio (e.g., 5:1 to 10:1 to catalyst) according to EP515933A using a silylated acid. In practice, however, it was subsequently found that the color numbers of the CDI-modified isocyanates obtained are rather poor, as are the prepolymers produced with them. The same applies to the acid terminated phospholene catalyst according to the trifluoromethanesulfonic acid type of US 6120699A. The color number of prepolymers made from these CDI/UTI modified isocyanates also increases significantly. CN1789241A discloses that the reaction is terminated by adopting an alkylating reagent such as trifluoromethyl sulfonate, the stability can be completely terminated by improving the molar equivalent ratio of the terminating agent to the catalyst, but the color number of the product is not ideal.

CN101003496A discloses controlling the addition conditions of the terminating agent to reduce the color number of the modified isocyanate, and the terminating agent is added in at least two batches. The temperature of the reaction mixture during the addition of the first batch of terminator was higher than the temperature of the reaction mixture during the addition of the second batch of terminator, but the product color number still reached 50 APHA.

In conclusion, the existing isocyanate liquefaction method generally has the problems of poor product color number and poor stability.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a preparation method of low-color-number carbodiimide modified isocyanate, and the modified isocyanate mixture obtained by the method contains Carbodiimide (CDI) and/or Uretonimine (UTI) derivatives, is liquid at normal temperature and has low color number, good normal-temperature storage and high-temperature stability.

The inventor surprisingly found that the content of CDI in the reaction liquid for preparing liquefied isocyanate by carbodiimide modification and the color number of the liquefied isocyanate product have a certain positive correlation, and the inventors found that the color number of the liquefied isocyanate product is darker as the content of CDI is higher when the color number of the liquefied isocyanate product is examined when the content of CDI is respectively 0 wt%, 0.5 wt%, 0.8 wt%, 1.8 wt%, 2.7 wt% and 4.9 wt%, and specifically shown in FIG. 1. Further analysis shows that CDI in the reaction liquid for preparing the liquefied isocyanate by modifying the carbodiimide can be oligomerized into CDI dimer under the synthesis process condition, and the CDI dimer can be converted into chromophoric substance with a conjugated structure under the acidic condition. It should be noted that the color development is related to the amount and strength of acid added, and the acid chloride is weak in acidity and high in color development tolerance. Based on the above findings, the inventors believe that the source of the chromonic material can be controlled by controlling the level of intermediate CDI during the liquefaction reaction.

However, in the liquefaction reaction, the conversion of the monomer to CDI and the conversion of CDI to UTI are both performed simultaneously, and both reaction rates are fast under the high temperature condition, but the reaction rate of the former is higher than that of the latter, i.e. the curing process of the conversion of CDI to UTI is relatively slow, which results in that the CDI content cannot be reduced in time in the liquefaction process; under the condition of low temperature, the conversion speed of the two types of the liquid phase is slow, and the reaction speed of the two types of the liquid phase is lower than that of the liquid phase, but the whole liquefaction reaction speed is slow and the reaction time is long. In order to solve the above problems and accelerate the decrease of CDI, the inventors found that by adding an acid chloride compound as a curing agent under high temperature conditions, it is possible to inhibit a part of the catalyst activity and slow the rate of conversion of monomers to CDI, thereby decreasing CDI to a target level in a short time.

Meanwhile, the inventor also finds that the catalyst remained in the liquefied isocyanate product is the main reason of poor product stability, and the un-terminated and still active catalyst still bleeds in normal temperature storage, so that the composition of the liquefied isocyanate product changes. The addition of the acyl chloride can inhibit partial catalyst activity, but the stability of the liquefied isocyanate product can be further improved by reducing the dosage of the catalyst and adding a terminator to terminate the reaction.

According to the above findings, the present invention adopts the following technical solutions:

a preparation method of carbodiimide modified isocyanate with low color number and high stability comprises the following steps:

s1: carrying out carbodiimide imidization on an isocyanate monomer to obtain a reaction solution containing Carbodiimide (CDI) and/or Uretonimine (UTI) groups;

s2: the content of CDI in the reaction liquid is reduced through the curing reaction, and the content of CDI is controlled to be 0.5-4.0 percent, preferably 1.0-1.5 percent, based on the total mass of the reaction liquid;

s3: the carbodiimidization reaction is terminated by adding a catalyst.

Wherein the CDI content directly affects the reaction color number, and the product color number deepens along with the increase of the CDI content in the figure. Meanwhile, if the content of CDI is too low or not good, the quality guarantee period of liquefaction and low-temperature stability are directly influenced, the molecular weights of CDI and dimer are similar, and if the content of CDI is less than 0.5%, the probability of dimer crystallization in a cyclic form is increased in a low-temperature environment, so that the product is turbid. Meanwhile, when the CDI is too low, the solubility of the dimer in the product is also reduced sharply, and the dimer is separated out along with the prolonging of the time, so that the liquefied product is turbid, and the shelf life of the product is shortened.

In the present invention, the isocyanate monomer in S1 is selected from one or more of aromatic diisocyanate, araliphatic diisocyanate and aliphatic diisocyanate, preferably aromatic diisocyanate, more preferably diphenylmethane diisocyanate, such as diphenylmethane diisocyanate containing 98 wt% to 100 wt% of 4, 4-isomer, 0 wt% to 1 wt% of 2, 2-isomer and 0 wt% to 1.8 wt% of 2, 4-isomer.

In the present invention, a phospholane catalyst is added to S1, preferably, the catalyst is one or more of a phospholane catalyst, a phospholane oxo catalyst, a phospholene catalyst, and a phospholene oxo catalyst, and more preferably, 1-methyl-3-phospholene-1-oxide; preferably, the catalyst is used in an amount of 1 to 5ppm, preferably 3 to 5ppm, based on the total weight of isocyanate monomer. The catalysts are highly effective catalysts known in the art, as described for example in EP515933A and US2663737A, typical examples of the use of these catalysts being known in the art.

In the present invention, the reaction temperature of S1 is 40-210 ℃, preferably 90-110 ℃.

As known in the art, after the high-temperature reaction is finished, a certain amount of diisocyanate monomer can be added, so that the reaction temperature is rapidly reduced, the dimer content is reduced, the monomer content is increased, and the production efficiency is improved.

In the invention, acyl chloride is added into S2 to accelerate the curing speed; the acid chloride is selected from one or more of methyl oxalyl chloride, ethyl oxalyl chloride and benzoyl chloride, preferably, methyl oxalyl chloride is used; preferably, the acid chloride is added in an amount of 3 to 10ppm, preferably 3 to 5ppm, based on the total weight of the reaction solution.

In the invention, the S2 is cured at 45-80 ℃ for 1-72 h, preferably 2-24 h.

In the present invention, the S3 is added with a terminator when the target CDI value is reached.

In the invention, the terminating agent of S3 is one or more of strong acid, trifluoromethyl sulfonic anhydride, trifluoromethyl sulfonic acid, boric acid, hydrogen fluoride and hydrogen chloride, and is preferably trifluoromethyl sulfonic anhydride; preferably, the amount of the terminator is 0 to 10ppm, preferably 2.5 to 10ppm, more preferably 5 to 7.5ppm, based on the total weight of the reaction solution.

Another object of the present invention is to provide a carbodiimide-modified isocyanate.

A carbodiimide modified isocyanate with low color number and high stability is obtained by adopting the preparation method.

In the present invention, the modified isocyanate contains CDI and/or UTI groups; preferably, the modified isocyanate contains 65-72 wt% of isocyanate monomer, 0.5-4.0 wt% of CDI, 10-20 wt% of UTI and 12-20 wt% of polymer; preferably, the modified isocyanate color number is 5 to 30 APHA.

In the present invention, unless otherwise specified, the% and ppm are mass contents.

By adopting the technical scheme, the invention has the following beneficial effects:

(1) the invention obtains the low color number modified product with the color number of 5-30APHA by controlling the CDI content in the reaction liquid during the liquefaction reaction of the isocyanate.

(2) According to the invention, acyl chloride added when the content of CDI is controlled can also inhibit part of catalyst activity, so that the stability of the liquefied isocyanate product is improved, the stability of the product can be further improved by reducing the dosage of the catalyst and adding a terminator to terminate the reaction, and the monomer reduction is only 0.1-1.0% after the product is degraded at 80 ℃ for 24 h.

(3) The method adopted by the invention is simple and convenient for industrial application.

Drawings

FIG. 1 shows the apparent color of a liquefied isocyanate product having a CDI content of 0 wt% (reference numeral 1), 0.5 wt% (reference numeral 2), 0.8 wt% (reference numeral 3), 1.8 wt% (reference numeral 4), 2.7 wt% (reference numeral 5), 4.9 wt% (reference numeral 6).

Detailed description of the preferred embodiments

The invention is further illustrated by the following examples, but the scope of the invention is not limited thereto.

Raw materials: diphenylmethane diisocyanate monomer, wherein the diphenylmethane diisocyanate contains 97 wt% to 100 wt% of 4, 4-isomer, 0 wt% to 1 wt% of 2, 2-isomer, and 0.5 wt% to 1.8 wt% of 2, 4-isomer, and has an NCO content of 33.6 wt%;

catalyst: 1-methyl-3-phosphole-1-oxide, 99.0%, mecillin; 1-phenyl-2-phospholene-1-oxide, 99.0%, mecillin.

Auxiliary agent: methyl oxalyl chloride, 97.0%, mecillin.

A terminating agent: trifluoromethanesulfonic anhydride, 98.0%, Michael.

Characterization of the instrument:

sample composition was characterized using Waters GPC-1515, testing monomer, CDI and UTI content. The product chromaticity is analyzed by a national standard method. The product was cured using a Shanghai Miura oven.

Example 1

1000g of diphenylmethane diisocyanate in N₂Heating to 50 ℃ under protection and stirring, adding 1.0ppm of 1-methyl-3-phosphole-1-oxide (based on the total weight of isocyanate monomers), mixing, rapidly heating to 110 ℃, reacting for 5h, then adding 500g of diphenylmethane diisocyanate, rapidly cooling to 60 ℃, stirring for 30min, adding 3.0ppm of methyl oxalyl chloride (based on the total weight of the reaction solution), curing for 4h, and adding 5.0ppm of terminator trifluoromethyl sulfonic anhydride when the CDI content is tested to be 0.5%, thus obtaining the final product.

Example 2

1000g of diphenylmethane diisocyanate in N₂Heating to 50 ℃ under protection and stirring, adding 1.0ppm of 1-methyl-3-phosphole-1-oxide (based on the total weight of isocyanate monomers), mixing, rapidly heating to 110 ℃, reacting for 5h, then adding 500g of diphenylmethane diisocyanate, rapidly cooling to 60 ℃, stirring for 30min, adding 5.0ppm of methyloxalyl chloride, curing for 2h, and adding 5.0ppm of terminator trifluoromethylsulfonic anhydride when the CDI content is tested to be 1.0%, thus obtaining the final product.

Example 3

1000g of diphenylmethane diisocyanate in N₂Heating to 50 ℃ under protection and stirring, adding 3.0ppm of 1-phenyl-2-cyclophospholene-1-oxide, mixing, rapidly heating to 110 ℃, reacting for 8h, then adding 500g of diphenylmethane diisocyanate, rapidly cooling to 60 ℃, stirring for 30min, adding 8.0ppm of methyl oxalyl chloride, curing for 2h, and adding 7.5ppm of terminator of trifluoromethylsulfonic anhydride when the CDI content is 1.0%, thus obtaining the final product.

Example 4

1000g of diphenylmethane diisocyanate in N₂Heating to 50 deg.C under stirring under protection, adding 3.0ppm of 1-methyl-3-phosphole-1-oxide, mixing, rapidly heating to 110 ℃, reacting for 3.5h, then adding 500g of diphenylmethane diisocyanate, rapidly cooling to 60 ℃, stirring for 30min, adding 5.0ppm of methyl oxalyl chloride, curing, and adding 8.0ppm of terminator trifluoromethanesulfonic acid when the CDI content is tested to be 2.0% after curing for 1.0h to obtain the final product.

Example 5

1000g of diphenylmethane diisocyanate in N₂Heating to 50 ℃ under protection and stirring, adding 3.0ppm of 1-methyl-3-phosphole-1-oxide, mixing, rapidly heating to 110 ℃, reacting for 3.5h, adding 500g of diphenylmethane diisocyanate, rapidly cooling to 60 ℃, stirring for 30min, adding 5.0ppm of ethyl oxalyl chloride, curing, and adding 8.0ppm of terminator trifluoromethanesulfonic acid when the CDI content is 3% after curing for 1.0h, thus obtaining the final product.

Example 6

1000g of diphenylmethane diisocyanate in N₂Heating to 50 ℃ under protection and stirring, adding 5.0ppm of 1-methyl-3-phosphole-1-oxide, mixing, rapidly heating to 110 ℃, reacting for 2.1h, adding 500g of diphenylmethane diisocyanate, rapidly cooling to 60 ℃, stirring for 30min, adding 5.0ppm of ethyl oxalyl chloride, curing, and adding 10.0ppm of hydrogen chloride gas serving as a terminator when the CDI content is 3.2% after curing for 1.0h to obtain the final product.

Example 7

1000g of hexamethylene diisocyanate in N₂Heating to 50 ℃ under protection and stirring, adding 3.0ppm of 1-methyl-3-phosphole-1-oxide, mixing, rapidly heating to 110 ℃, reacting for 7h, then adding 500g of hexamethylene diisocyanate, rapidly cooling to 60 ℃, stirring for 30min, adding 5.0ppm of methyl oxalyl chloride for curing, and adding 5.0ppm of terminator trifluoromethyl sulfonic anhydride when the CDI content is tested to be 1.00% after curing for 4.0h to obtain the final product.

Comparative example 1

Compared with the example 2, the reaction solution is not cured, the terminator is directly added after the temperature is reduced, and compared with the influence of the increase of the CDI content on the color number of the product, the color number of the final product, namely 80APHA, can be found, and the specific implementation is as follows:

1000g of diphenylmethane diisocyanate in N₂Heating to 50 ℃ under protection and stirring, adding 1.0ppm of 1-methyl-3-phosphole-1-oxide, mixing, rapidly heating to 110 ℃, reacting for 5.0h, then adding 500g of diphenylmethane diisocyanate, rapidly cooling to 60 ℃, stirring for 30min, testing the CDI content to be 5.82%, and then adding 5.0ppm of terminator trifluoromethyl sulfonic anhydride to obtain the final product.

Comparative example 2

In comparison with example 4, in comparative example 2, the acid chloride was added without aging, and at a high CDI content, a high amount of the terminator was added directly. Comparing the influence of the increased CDI content on the color number of the product, the color number of the final product, namely 135APHA, can be found, and the specific implementation is as follows:

1000g of diphenylmethane diisocyanate in N₂Heating to 50 ℃ under protection and stirring, adding 3.0ppm of 1-methyl-3-phosphole-1-oxide, mixing, rapidly heating to 110 ℃, reacting for 3.5h, then adding 500g of diphenylmethane diisocyanate, rapidly cooling to 60 ℃, stirring for 30min, testing the CDI content to be 4.56%, adding 5.0ppm of methyl oxalyl chloride, and then directly adding 20.0ppm of terminator of trifluoromethyl sulfonic anhydride to obtain the final product.

Comparative example 3

When the content of CDI is reduced to 0.2% compared with example 1, adding a terminator can find that the product shelf life is shortened and the product becomes turbid due to too low content of CDI, and the specific implementation is as follows

1000g of diphenylmethane diisocyanate in N₂Heating to 50 ℃ under protection and stirring, adding 1.0ppm of 1-methyl-3-phosphole-1-oxide, mixing, rapidly heating to 110 ℃, reacting for 5h, then adding 500g of diphenylmethane diisocyanate, rapidly cooling to 60 ℃, stirring for 30min, adding 3.0ppm of methyl oxalyl chloride (based on the total weight of the reaction solution), curing for 6h, and adding 20.0ppm of terminator trifluoromethyl sulfonic anhydride when the CDI content is tested to be 0.21%, thus obtaining the final product.

The examples and comparative examples are compared as follows:

the examples and comparative examples were compared with other parameters as follows:

	isocyanate monomer/%)	UTI/％	Multimer/%	Appearance after 4 months of storage
					Example 1	69.29	15.83	14.35	Clarification
Example 2	69.41	15.28	14.26	Clarification
					Example 3	69.92	15.15	13.88	Clarification
Example 4	71.11	13.43	13.47	Clarification
					Example 5	71.30	12.92	12.72	Clarification
Example 6	71.19	12.03	13.56	Clarification
					Example 7	68.61	15.39	15.00	Clarification
Comparative example 1	71.72	10.30	12.16	Clarification
					Comparative example 2	71.39	11.37	12.68	Clarification
Comparative example 4	69.00	15.69	15.10	Turbidity

The experimental results in table 1 show that the method for reducing the color number of the carbodiimide-modified organic isocyanate accelerates the curing speed by adding acyl chloride, rapidly reduces the content of CDI in the reaction solution to a set range, and then adds the acidic terminator, so that the color number of the product is significantly reduced to 5-30APHA, and the color number of the product is still lower compared with that of a commercially available product.

While the present invention has been described in detail with reference to the preferred embodiments thereof, it should be understood that the above description should not be taken as limiting the invention. It will be appreciated by those skilled in the art that modifications or adaptations to the invention may be made in light of the teachings of the present specification. Such modifications or adaptations are intended to be within the scope of the present invention as defined in the claims.