Isocyanate-modified chain-extended polyol, preparation method and application thereof

Abstract

The present invention discloses an isocyanate-modified chain-extended polyol, a preparation method, and an application thereof. The preparation method comprises the following steps: step 1, dehydrating the polyol raw material; step 2, placing the dehydrated polyol raw material into a microwave reactor, and adding an anti-riot agent for mechanical stirring, wherein the anti-riot agent is one or more of phosphoric acid and trifluoromethanesulfonic acid; step 3, adding isocyanate to the microwave reactor and turning on the microwave reactor for insulation; step 4, filtering the product in the microwave reactor to obtain an isocyanate-modified chain-extended polyol. By adding an anti-riot agent, the present invention makes the molecular weight of the obtained isocyanate-modified chain-extended polyol narrower, effectively avoids violent polymerization of the reaction, and makes the reaction more stable. The obtained isocyanate-modified chain-extended polyol is used for the preparation of PU potting glue, can reduce the maximum reaction temperature, is suitable for the preparation of temperature-sensitive electronic components, and can improve the elongation at break of the PU potting glue.

Description

Technical Field

[0001] The present invention relates to the technical field of material preparation, and in particular to an isocyanate-modified chain-extended polyol, a preparation method and an application thereof. Background Art

[0002] Currently, the operational and performance requirements for various functional polyurethane products are becoming increasingly stringent, and many monomeric small-molecule polyols are no longer able to meet the formulation requirements. Using a microwave method, functional isocyanate-chain-extended polyols with a narrower molecular weight distribution can be efficiently synthesized. This can address many applications sensitive to exothermic heat (e.g., lithium batteries, carbonization issues in bulk PU foam, and potting of heat-sensitive electronic components). Chinese invention patent application publication number CN 200910135824.9, titled "A Microwave Synthesis Method for Polyester Polyols for Polyurethane Shoe Soles," also points out the advantages of microwave-synthesized polyester polyols, including low energy consumption and high product quality. However, the reaction between isocyanates and alcoholic hydroxyl groups is exothermic, posing the risk of sudden polymerization during microwave synthesis. Summary of the Invention

[0003] Purpose of the invention: In view of the above shortcomings, the present invention provides an isocyanate-modified chain-extended polyol, a preparation method and application.

[0004] Technical solution: To solve the above problems, the present invention adopts an isocyanate-modified chain-extended polyol with a molecular weight of 400-1100, a functionality of 2, and a viscosity of 1500-8300 MPa.s.

[0005] The present invention also provides a method for preparing the above-mentioned isocyanate-modified chain-extended polyol, comprising the following steps:

[0006] Step 1, dehydrating the polyol raw material;

[0007] Step 2: putting the dehydrated polyol raw material into a microwave reactor, adding an anti-riot agent and mechanically stirring the mixture, wherein the anti-riot agent is at least one of phosphoric acid and trifluoromethanesulfonic acid;

[0008] Step 3, adding isocyanate to the microwave reactor and opening the microwave reactor to keep warm;

[0009] Step 4: Filter the product in the microwave reactor to obtain an isocyanate-modified chain-extended polyol.

[0010] Furthermore, the added mass of the anti-riot agent is 0.02%-0.06% of the mass of the dehydrated polyol raw material.

[0011] Furthermore, the dehydrated polyol is expected to have a moisture content of less than 500 ppm.

[0012] Furthermore, polyol raw materials and isocyanate are added so that the ratio of the molar number of NCO to the molar number of hydroxyl is 1:2.

[0013] Furthermore, the isocyanate is at least one of TDI, MDI, and IPDI.

[0014] Furthermore, the polyol raw material has a hydroxyl value in the range of 270-1255 mgKOH / g and a functionality of 2-3.

[0015] Furthermore, the mechanical stirring temperature is set at 60-65° C.; the insulation temperature is 60-65° C., and the insulation time is 1-3 hours.

[0016] Furthermore, the microwave frequency of the microwave reactor is 2450±50 MHz, and the power of a single microwave tube is 50 to 500 watts.

[0017] The present invention also provides application of the isocyanate-modified chain-extended polyol in the preparation of PU potting adhesive.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) by adding an anti-explosion agent, the molecular weight of the obtained isocyanate-modified extended chain polyol is narrower, and the reaction is effectively prevented from undergoing polymerization, making the reaction more stable; (2) the obtained isocyanate-modified extended chain polyol is used in the preparation of PU potting adhesive, which can reduce the maximum reaction temperature and is suitable for the preparation of temperature-sensitive electronic components. It can also increase the elongation at break of the obtained PU potting adhesive and improve the toughness of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the GPC chart of the isocyanate-modified chain-extended polyol prepared in Example 1;

[0020] Figure 2 This is the GPC chart of the isocyanate-modified chain-extended polyol prepared in Example 2;

[0021] Figure 3 This is the GPC chart of the isocyanate-modified chain-extended polyol prepared in Example 3;

[0022] Figure 4 This is the GPC chart of the isocyanate-modified chain-extended polyol obtained in Example 4;

[0023] Figure 5 This is the GPC chart of the isocyanate-modified chain-extended polyol prepared in Comparative Example 1. DETAILED DESCRIPTION

[0024] Example 1

[0025] The preparation method of an isocyanate-modified chain-extended polyol in this embodiment comprises the following steps:

[0026] Step 1: Dehydrate the polyol raw material to reduce the moisture content of the dehydrated polyol to less than 500 ppm. The polyol raw material used in this example is NJ-204 (Liangguan 400 molecular weight diol from Ningwu, Jurong, Zhenjiang, Jiangsu), with a hydroxyl value of 270-290 mgKOH / g.

[0027] Step 2: 50 parts by mass of the dehydrated polyol raw material is put into a microwave reactor, and 0.06% by mass of trifluoromethanesulfonic acid (i.e., 0.03 parts by mass of trifluoromethanesulfonic acid) of the mass percentage of the polyol raw material is added, and mechanical stirring is performed at 65° C.

[0028] Step 3: Add 15.7 parts by mass of isocyanate to a microwave reactor while stirring. The microwave reactor was then incubated at 65°C for 3 hours. The isocyanate used in this example was MDI-50 (Yantai Wanhua 2,4-diphenylmethane diisocyanate). The NCO index of the polyol and isocyanate added as reaction materials was 50, meaning the ratio of NCO molecules to hydroxyl groups in the two raw materials was 1:2. The microwave frequency of the microwave reactor was 2450±50 MHz, and the power of a single microwave tube was 50-500 watts.

[0029] Step 4: Filter the product in the microwave reactor to obtain an isocyanate-modified chain-extended polyol. The molecular formula of the obtained isocyanate-modified chain-extended polyol is as follows: The molecular weight is 1000-1050 and the viscosity is about 1500-2000Mpa.s.

[0030] Example 2

[0031] The preparation method of an isocyanate-modified chain-extended polyol in this embodiment comprises the following steps:

[0032] Step 1: Dehydrate the polyol raw material to reduce the moisture content of the dehydrated polyol raw material to less than 500 ppm. The polyol used in this embodiment is dipropylene glycol, which has a hydroxyl value of 835-845 mgKOH / g.

[0033] Step 2: 50 parts by mass of the dehydrated polyol was put into a microwave reactor, and 0.02% by mass of trifluoromethanesulfonic acid (i.e., 0.01 parts by mass of trifluoromethanesulfonic acid) of the polyol raw material was added, and mechanical stirring was performed at 60°C.

[0034] Step 3: Add 47 parts by mass of isocyanate to a microwave reactor while stirring. The microwave reactor was then incubated at 60°C for 1 hour. The isocyanate used in this example was MDI-50 (Yantai Wanhua 2,4-diphenylmethane diisocyanate). The NCO index of the polyol and isocyanate added as reaction materials was 50. The microwave frequency of the microwave reactor was 2450 ± 50 MHz, and the power of a single microwave tube was 50 to 500 watts.

[0035] Step 4: Filter the product in the microwave reactor to obtain an isocyanate-modified chain-extended polyol. The molecular formula of the obtained isocyanate-modified chain-extended polyol is as follows: The molecular weight is 500-520 and the viscosity is about 8000-8300Mpa.s.

[0036] Example 3

[0037] The preparation method of an isocyanate-modified chain-extended polyol in this embodiment comprises the following steps:

[0038] Step 1: Dehydrate the polyol raw material to reduce the moisture content of the dehydrated polyol raw material to less than 500 ppm. The polyol used in this embodiment is 1,4-butanediol, which has a hydroxyl value of 1245-1255 mgKOH / g.

[0039] Step 2: 50 parts by mass of the dehydrated polyol raw material is put into a microwave reactor, and 0.04% by mass of trifluoromethanesulfonic acid (i.e., 0.02 parts by mass of trifluoromethanesulfonic acid) of the polyol raw material is added, and mechanical stirring is performed at 60°C.

[0040] Step 3: Add 70 parts by weight of isocyanate to a microwave reactor while stirring. The microwave reactor was then incubated at 60°C for 2 hours. The isocyanate used in this example was MDI-50 (Yantai Wanhua 2,4-diphenylmethane diisocyanate). The NCO index of the polyol and isocyanate added to the reaction mixture was 50. The microwave frequency of the microwave reactor was 2450 ± 50 MHz, and the power of a single microwave tube was 50 to 500 watts.

[0041] Step 4: Filter the product in the microwave reactor to obtain an isocyanate-modified chain-extended polyol. The molecular formula of the obtained isocyanate-modified chain-extended polyol is as follows: The molecular weight is 400-430 and the viscosity is about 3000-3500Mpa.s.

[0042] Example 4

[0043] The preparation method of an isocyanate-modified chain-extended polyol in this embodiment comprises the following steps:

[0044] Step 1: Dehydrate the polyol raw material to reduce the moisture content of the dehydrated polyol raw material to less than 500 ppm. The polyol used in this embodiment is 1,4-butanediol, which has a hydroxyl value of 1245-1255 mgKOH / g.

[0045] Step 2: 50 parts by mass of the dehydrated polyol raw material is put into a microwave reactor, and 0.04% by mass of phosphoric acid (i.e., 0.02 parts by mass of phosphoric acid) of the polyol raw material is added, and mechanical stirring is performed at 60°C.

[0046] Step 3: Add 70 parts by mass of isocyanate to a microwave reactor while stirring. The microwave reactor was then incubated at 60°C for 2 hours. The isocyanate used in this example was MDI-50 (Yantai Wanhua 2,4-diphenylmethane diisocyanate). The NCO index of the polyol and isocyanate added as reaction materials was 50. The microwave frequency of the microwave reactor was 2450 ± 50 MHz, and the power of a single microwave tube was 50 to 500 watts.

[0047] Step 4: Filter the product in the microwave reactor to obtain an isocyanate-modified chain-extended polyol. The molecular formula of the obtained isocyanate-modified chain-extended polyol is as follows: The molecular weight is 400-420 and the viscosity is about 2800-3100Mpa.s.

[0048] Comparative Example 1

[0049] The preparation method of an isocyanate-modified chain-extended polyol in this embodiment comprises the following steps:

[0050] Step 1: Dehydrate the polyol raw material to reduce the moisture content of the dehydrated polyol raw material to less than 500 ppm. The polyol used in this example is NJ-204 (Liangguan 400 molecular weight diol, Ningwu, Jurong, Zhenjiang, Jiangsu), with a hydroxyl value of 270-290 mgKOH / g.

[0051] Step 2: 50 parts by mass of the dehydrated polyol raw material was put into a microwave reactor and mechanically stirred at 65°C.

[0052] Step 3: Add 15.7 parts by mass of isocyanate to a microwave reactor while stirring. The microwave reactor was then incubated at 65°C for 3 hours. The isocyanate used in this example was MDI-50 (Yantai Wanhua 2,4-diphenylmethane diisocyanate). The NCO index of the polyol and isocyanate added as reaction materials was 50. The microwave frequency of the microwave reactor was 2450 ± 50 MHz, and the power of a single microwave tube was 50 to 500 watts.

[0053] Step 4: Filter the product in the microwave reactor to obtain an isocyanate-modified chain-extended polyol. The molecular formula of the obtained isocyanate-modified chain-extended polyol is as follows: The molecular weight is 800-1060 and the viscosity is about 1500-2000Mpa.s.

[0054] Result Analysis

[0055] like Figures 1 to 5 As shown, the first peak in the figure is the product peak. Figures 1-4 The peak is sharper, the peak width is narrower, and no tailing peak appears, indicating that the molecular weight of the obtained product is narrower and the reaction does not undergo sudden polymerization, proving that the addition of the anti-explosion agent has a corresponding effect. At the same time, the peak of Example 4 is sharper and the molecular weight of the obtained product is narrower, indicating that phosphoric acid is more effective than trifluoromethanesulfonic acid and is more conducive to narrowing the product molecular weight distribution and avoiding sudden polymerization.

[0056] In order to further analyze the effect of the obtained product on the viscosity of the product when used in the subsequent preparation of potting PU glue, the products obtained in each example were mixed with heavy calcium powder in a ratio of 1:1, and the viscosity of the obtained mixed product was measured. The results are as follows:

[0057]

[0058] As can be seen from the data in the above table, the isocyanate-modified extended chain polyols obtained in Examples 1, 3, and 4 have lower viscosity after mixing with heavy calcium powder, which is beneficial to the dispensing operation of subsequent products. In Example 2, since dipropylene glycol is used as the polyol material, although the molecular weight of the prepared product is narrow, the side chains contained in its structure have a certain effect on the viscosity of the product, so the viscosity of the product is relatively large, and the polyol can be selected according to actual needs to obtain the desired effect. The viscosity value of the product obtained in Example 1 is the same as that of the comparative example 1, but since the molecular weight of the product obtained in Example 1 is narrower, the viscosity obtained after Example 1 is mixed with heavy calcium powder is also lower, indicating that the isocyanate-modified extended chain polyol with a narrower molecular weight obtained by the present invention is more suitable for the subsequent preparation of PU glue and has better performance.

[0059] Example 5

[0060] The present invention also provides the use of the prepared isocyanate-modified chain-extended polyol in the preparation of a PU potting compound. The isocyanate-modified chain-extended polyol prepared in Examples 1-4 and Comparative Example 1, dehydrated castor oil, and 1250-mesh heavy calcium powder were mixed in a mass ratio of 10:90:100 and vacuum degassed to prepare component A. Component A was then mixed with PM200 in a mass ratio of 100:20 and cured to prepare a PU potting compound. The potting compounds prepared in Examples 1-4 and Comparative Example 1 are numbered products 1-5, respectively.

[0061] For comparison, the isocyanate-modified chain-extended polyol was replaced with dipropylene glycol and 1,4-butanediol to prepare PU potting compounds. Products 6 and 7 were obtained, respectively. The elongation at break and the maximum temperature during preparation of products 1-7 were measured, and the results are shown in the following table:

[0062]

[0063] From the data in the table, it can be seen that the maximum reaction temperature of products 6 and 7 prepared using non-chain-extended polyols reaches 98 and 106°C, which is significantly higher than the reaction temperature of products prepared using isocyanate-modified extended polyols. They cannot be used in the preparation of temperature-sensitive electronic components, such as the electronic potting glue industry, which requires the maximum reaction temperature of the material to not exceed 50°C. The extended polyols can be used to prepare materials that have more stringent temperature requirements and are sensitive. Although the elongation at break of product 5 obtained using the isocyanate-modified extended polyol prepared in Comparative Example 1 is higher than that of products 6 and 7, it is significantly lower than that of products 1-4, indicating that the anti-riot polymerization treatment is beneficial to improving the elongation at break of the material. And by comparing product 3 with product 4, it can be seen that compared with trifluoromethanesulfonic acid, phosphoric acid as an anti-riot agent is also more conducive to improving the elongation at break of the material.

Claims

1. A method for preparing an isocyanate-modified chain-extended polyol, characterized in that: The following steps are involved: Step 1: Dehydrating a polyol raw material; the polyol raw material has a hydroxyl value in the range of 270-1255 mgKOH / g and a functionality of 2; the moisture content of the dehydrated polyol raw material is less than 500 ppm; Step 2: putting the dehydrated polyol raw material into a microwave reactor, adding an anti-riot agent and mechanically stirring the mixture, wherein the anti-riot agent is at least one of phosphoric acid and trifluoromethanesulfonic acid; the added mass of the anti-riot agent is 0.02%-0.06% of the mass of the dehydrated polyol raw material; Step 3, adding isocyanate to a microwave reactor and turning on the microwave reactor to keep it warm; adding polyol raw material and isocyanate so that the ratio of NCO mole to hydroxyl mole is 1:2; the isocyanate is at least one of TDI, MDI, and IPDI; Step 4: Filter the product in the microwave reactor to obtain an isocyanate-modified chain-extended polyol.

2. The method for preparing an isocyanate-modified chain-extended polyol according to claim 1, wherein The mechanical stirring temperature is set at 60-65° C.; the insulation temperature is 60-65° C., and the insulation time is 1-3 hours.

3. The method for preparing an isocyanate-modified chain-extended polyol according to claim 1, wherein The microwave frequency of the microwave reactor is 2450±50 MHz, and the power of a single microwave tube is 50-500 watts.

4. An isocyanate-modified chain-extended polyol prepared by the method for preparing an isocyanate-modified chain-extended polyol according to any one of claims 1 to 3, characterized in that: The molecular weight is 400-1100, the functionality is 2, and the viscosity is 1500-8300 Mpa.s.

5. Use of the isocyanate-modified chain-extended polyol according to claim 4 in the preparation of PU potting compound.

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