Calcium hexahydrophthalate, its preparation method and application

Abstract

This application relates to the field of the preparation of nucleating agent materials, and particularly relates to calcium hexahydrophthalate, a preparation method thereof, and an application thereof. A preparation method of calcium hexahydrophthalate includes the following steps: Dissolution: Dissolve hexahydrophthalic acid in an alcohol to obtain a hexahydrophthalic acid-alcohol solution; Acid-base neutralization: Add calcium hydroxide into the hexahydrophthalic acid-alcohol solution for reaction, and after filtration, dry to obtain calcium hexahydrophthalate. In this application, by carrying out an acid-base neutralization reaction between hexahydrophthalic acid and calcium hydroxide in an alcohol liquid, most of the generated water molecules are adsorbed by the alcohol liquid, so that it is difficult to combine with calcium hexahydrophthalate to form a crystalline hydrate. At the same time, only the alcohol liquid and trace free water need to be removed during drying, reducing the energy consumption and time cost.

Description

Technical Field

[0001] This application relates to the field of nucleating agent material preparation, and particularly relates to calcium hexahydrophthalate, a preparation method thereof, and an application thereof. Background Art

[0002] Calcium hexahydrophthalate is a commonly used rigidifying nucleating agent product, which can significantly increase the flexural modulus of polypropylene products, reduce the haze, and at the same time reduce the shrinkage rate of products, effectively inhibiting product warping. The application effect of calcium hexahydrophthalate is closely related to the amount of crystal water it contains. When there is crystal water in it, the product performance deteriorates, especially the haze value will increase significantly. In the prior art, calcium hexahydrophthalate usually uses hexahydrophthalic anhydride as a raw material and water as a solvent. The hexahydrophthalic anhydride is put into water for hydrolysis to generate hexahydrophthalic acid, and then calcium hydroxide is added to carry out an acid-base neutralization reaction to obtain calcium hexahydrophthalate. Since the reaction is carried out in an aqueous solution system and water is generated during the acid-base neutralization, the calcium hexahydrophthalate molecules generated all contain one crystal water. This crystal water is difficult to remove during the drying process, with high cost and it is difficult to remove completely, ultimately affecting the product application effect. Summary of the Invention

[0003] In order to solve the problem that in the prior art, when preparing calcium hexahydrophthalate in an aqueous solution system, the final product combines with crystal water, affecting the effect of calcium hexahydrophthalate as a nucleating agent. This application provides a preparation method of calcium hexahydrophthalate, which is carried out in an alcohol solution system. By using the strong water adsorption property of alcohol, it is difficult for calcium hexahydrophthalate to combine with water molecules, improving the performance of the final product and being able to better enhance the flexural modulus of polypropylene and reduce the haze.

[0004] In the first aspect, this application provides a preparation method of calcium hexahydrophthalate, adopting the following technical solution:

[0005] A preparation method of calcium hexahydrophthalate includes the following steps:

[0006] Dissolution: Dissolve hexahydrophthalic acid in alcohol to obtain a hexahydrophthalic acid-alcohol solution;

[0007] Acid-base neutralization: Add calcium hydroxide to the hexahydrophthalic acid-alcohol solution for reaction, and after filtration and drying, obtain calcium hexahydrophthalate.

[0008] By adopting the above technical solution, by dissolving hexahydrophthalic acid in alcohol, a uniform hexahydrophthalic acid-alcohol solution can be formed, which helps the uniform dispersion of hexahydrophthalic acid and sufficient contact with calcium hydroxide, thereby improving the efficiency and rate of the acid-base neutralization reaction. Hexahydrophthalic acid and calcium hydroxide undergo an acid-base neutralization reaction to produce calcium hexahydrophthalate and water. In the conventional process, the generated calcium hexahydrophthalate usually combines with water molecules to form a crystalline hydrate. In this application, due to the strong affinity of alcohol liquids for water molecules, most of the water molecules are adsorbed by the alcohol liquids, thus reducing the chance of combination between calcium hexahydrophthalate and water molecules. This helps to obtain anhydrous or less hydrated calcium hexahydrophthalate.

[0009] In the traditional preparation method, the drying process may require removing a large amount of water, which usually takes a long time and high energy consumption. In this solution, due to the use of alcohol solvents and the adsorption of water molecules, only alcohol liquids and trace amounts of free water need to be removed during the drying process. This greatly simplifies the drying process and reduces the energy consumption and time cost.

[0010] In this application, by carrying out an acid-base neutralization reaction between hexahydrophthalic acid and calcium hydroxide in an alcohol liquid, most of the generated water molecules are adsorbed by the alcohol liquid, making it difficult to combine with calcium hexahydrophthalate to form a crystalline hydrate. At the same time, only alcohol liquids and trace amounts of free water need to be removed during drying, reducing the energy consumption and time cost.

[0011] Preferably, in the dissolving step, the alcohol includes at least one of methanol, ethanol, ethylene glycol, propylene glycol, and glycerol.

[0012] Preferably, the alcohol is methanol.

[0013] By adopting the above technical solution, methanol, ethanol, ethylene glycol, propylene glycol, and glycerol all contain a hydroxyl (-OH) functional group, which enables them to form hydrogen bonds with water molecules, thereby showing strong water affinity.

[0014] Among them, due to its relatively small molecular structure and the relatively exposed hydroxyl functional group, methanol has a strong interaction with water molecules and is prone to forming hydrogen bonds, thus showing strong adsorption. The molecular chain of ethanol is relatively long, and the position of the hydroxyl functional group in the molecule is relatively "hidden", which may result in a slightly weaker interaction between ethanol and water molecules than that of methanol. Therefore, from the perspective of adsorption, ethanol may not be as strong as methanol.

[0015] In addition, ethylene glycol, propylene glycol, and glycerol have relatively high viscosities, and it is not as convenient to stir and react hexahydrophthalic acid and calcium hydroxide in them as in methanol. Therefore, relatively speaking, methanol is a better choice.

[0016] Preferably, the mass ratio of hexahydrophthalic acid to alcohol is 1:6 - 10.

[0017] By adopting the above technical solution, when the content of alcohol is too low, hexahydrophthalic acid may not be fully dissolved, resulting in incomplete reaction. The shortage of alcohol may also affect the dispersion and reaction of calcium hydroxide, reducing the reaction rate and efficiency. The shortage of alcohol may reduce the fluidity of the reaction system, increasing the difficulty of stirring and mixing. This may lead to uneven reaction, affecting the quality and uniformity of the product. When the content of alcohol is too high, hexahydrophthalic acid and calcium hydroxide can already react fully.

[0018] Preferably, in the step of acid-base neutralization, the reaction time is 1 - 2 h.

[0019] By adopting the above technical solution, the acid-base neutralization reaction is usually a relatively fast reaction, but the specific reaction rate will be affected by factors such as reactant concentration, temperature, and stirring degree. Controlling the reaction time within 1 - 2 hours can ensure that the reaction is completed within a reasonable time. By controlling the reaction time, it can be ensured that calcium hydroxide reacts fully with hexahydrophthalic acid to produce the required calcium hexahydrophthalate. Too short a reaction time may result in incomplete reaction, while too long a reaction time is unnecessary.

[0020] Preferably, the method for preparing calcium hexahydrophthalate further includes adding an adsorbent to the hexahydrophthalic acid-alcohol solution, and the adsorbent includes zeolite, activated carbon, and silica gel.

[0021] By adopting the above technical solution, zeolite, activated carbon, and silica gel, these adsorbents have higher water adsorption than alcohol liquids, can further adsorb the water molecules generated by the acid-base neutralization reaction, reduce the content of free water in the solution, and thus improve the quality of calcium hexahydrophthalate.

[0022] Preferably, the mass ratio of hexahydrophthalic acid to the adsorbent is 1:0.1 - 0.3.

[0023] By adopting the above technical solution, when the content of the adsorbent is too low, its adsorption capacity may not be sufficient to completely remove the water molecules generated by the reaction, making it difficult to further improve the performance of calcium hexahydrophthalate. When the content of the adsorbent is too high, there are very few water molecules at this time, and it is difficult to further increase the performance of calcium hexahydrophthalate, and there is no need to continue adding the content of the adsorbent.

[0024] Preferably, after calcium hydroxide is added to the hexahydrophthalic acid-alcohol solution and reacts for 0.4 - 0.8 h, the adsorbent is added to the hexahydrophthalic acid-alcohol solution.

[0025] By adopting the above technical solution, the adsorbent has a greater water adsorption capacity than alcohol liquids. However, if the adsorbent is added to the hexahydrophthalic acid-alcohol solution prematurely, that is, before the calcium hydroxide has fully reacted, the adsorbent may preferentially adsorb the alcohol liquids in the solution. Once the adsorbent is occupied by the alcohol liquids, its adsorption capacity will be greatly reduced, making it difficult to effectively adsorb the water molecules generated in the subsequent reaction.

[0026] On the contrary, if the adsorbent is added too late, that is, after the reaction between calcium hydroxide and hexahydrophthalic acid is complete and a large amount of water molecules are generated, the adsorbent may not play an effective adsorption role. Because at this time, the free water molecules in the solution may have formed a certain concentration gradient or distribution state, and some water molecules may have combined with the products or other components. Adding the adsorbent at this time can adsorb some free water molecules, but may not be able to completely remove all the water, thus affecting the drying effect and final quality of the product.

[0027] In a second aspect, the present application provides a calcium hexahydrophthalate, adopting the following technical solution:

[0028] A calcium hexahydrophthalate is prepared by the preparation method of the above calcium hexahydrophthalate.

[0029] In a third aspect, the present application provides an application of calcium hexahydrophthalate, adopting the following technical solution:

[0030] An application of calcium hexahydrophthalate is the application of the above calcium hexahydrophthalate in polypropylene.

[0031] By adopting the above technical solution, the calcium hexahydrophthalate contains very little bound water during the preparation process, which helps it better play the role of a nucleating agent. By adding calcium hexahydrophthalate, the flexural modulus of polypropylene can be effectively improved. Adding calcium hexahydrophthalate to polypropylene can also effectively reduce its haze and improve transparency.

[0032] In summary, the present application has the following beneficial effects:

[0033] 1. Since in the present application, the acid-base neutralization reaction between hexahydrophthalic acid and calcium hydroxide is carried out in an alcohol liquid, most of the generated water molecules are adsorbed by the alcohol liquid, making it difficult to combine with calcium hexahydrophthalate to form a crystalline hydrate. At the same time, only the alcohol liquid and trace free water need to be removed during drying, reducing the energy consumption and time cost;

[0034] 2. The alcohol used in the present application is methanol, which has a stronger water adsorption property, lower viscosity, and is easier to stir compared to other alcohols;

[0035] 3. The present application can also add adsorbents such as zeolite, activated carbon, and silica gel, which can further absorb water molecules and further improve the performance of calcium hexahydrophthalate. Detailed implementation mode

[0036] The raw materials in the present application include the following parts:

[0037] Hexahydrophthalic acid: Use a commercially available product with a CAS number of 610-09-3;

[0038] Methanol: Use a commercially available product with a CAS number of 67-56-1;

[0039] Ethanol: Use a commercially available product with a CAS number of 64-17-5;

[0040] Ethylene glycol: Use a commercially available product with a CAS number of 107-21-1;

[0041] Propylene glycol: Use a commercially available product with a CAS number of 57-55-6;

[0042] Glycerol: Use a commercially available product with a CAS number of 56-81-5;

[0043] Calcium hydroxide: Use a commercially available product with a CAS number of 13025-62-0;

[0044] Zeolite: Use a commercially available product with a CAS number of 1318-02-1;

[0045] Activated carbon: Use a commercially available product with a CAS number of 64365-11-3;

[0046] Silica gel: Use a commercially available product with a CAS number of 112926-00-8;

[0047] The present application will be further described in detail below in conjunction with examples and comparative examples. Example 1

[0048] A preparation method of calcium hexahydrophthalate includes the following steps:

[0049] Dissolution: Dissolve 10 g of hexahydrophthalic acid in 90 g of methanol to obtain a hexahydrophthalic acid-alcohol solution;

[0050] Acid-base neutralization: Put 25 g of calcium hydroxide into the hexahydrophthalic acid-alcohol solution for reaction, react for 2 h, filter and dry at 120 °C for 0.5 h to obtain calcium hexahydrophthalate.

[0051] Examples 2-5

[0052] Based on the preparation method of Example 1, the addition amount of methanol in Examples 2-5 was adjusted, and the specific adjustment is shown in Table 1.

[0053] Comparative Examples 1-2

[0054] Comparative Example 1

[0055] A method for preparing calcium hexahydrophthalate, comprising the following steps:

[0056] Hydrolysis: Dissolve 10 g of hexahydrophthalic acid in 100 g of water to obtain a hexahydrophthalic acid solution;

[0057] Acid-base neutralization: Add 25 g of calcium hydroxide to the hexahydrophthalic acid solution and react for 2 h. After filtration, dry at 120 °C for 0.5 h to obtain calcium hexahydrophthalate.

[0058] In Comparative Example 2, based on the preparation method of Example 1, the drying time was extended from 0.5 h to 3 h, and the other conditions remained unchanged.

[0059] Table 1 Methanol addition amounts and performance test table of Examples 1-5 and Comparative Examples 1-2

[0060] Project Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Methanol / g 100 50 60 90 110 / / Flexural Modulus / MPa 1151 1071 1102 1138 1152 956 983 Haze / % 15.6 25.7 21.2 17.1 15.6 46.8 44.5

[0061] Performance detection test

[0062] After modifying polypropylene with hexahydrophthalic acid of Examples 1-5 and Comparative Examples 1-2, the following performance detections were carried out, and the detection results are shown in Table 1.

[0063] A method for preparing modified polypropylene, comprising the following steps:

[0064] (1) Kneading

[0065] Put 1000 g of polypropylene and 5 g of calcium hexahydrophthalate into a mixer, knead for 10 min, and discharge the rubber at 65 °C to obtain a kneaded rubber;

[0066] (2) Open mill

[0067] Pass the kneaded rubber through the open mill 3 times, open mill for 5 min until it is evenly opened, and cut into sheets to obtain a master sheet;

[0068] (3) Pelletizing

[0069] Subsequently, put the master sheet into a pelletizer and pelletize at a temperature of 50 °C to obtain modified polypropylene.

[0070] 1. Flexural modulus

[0071] Test the modified polypropylene according to the standard of GB / T9341-2008.

[0072] 2. Haze

[0073] The modified polypropylene was tested according to the standard of GB / T 2410-2008 (with a thickness of 1 mm).

[0074] Referring to Table 1, by comparing Examples 1-5 and Comparative Examples 1-2, it can be seen that compared with Comparative Examples 1-2, the flexural modulus of Examples 1-5 is much higher than that of Comparative Examples 1-2, and the haze is much lower than that of Comparative Examples 1-2. Especially for Comparative Example 2, even if it is dried for more time later, the effect is still not as good as that of Examples 1-5. This shows that when preparing calcium hexahydrophthalate by reaction in methanol, there is less crystal water, which can better play the role of calcium hexahydrophthalate as a nucleating agent, thereby improving the flexural modulus of the modified polypropylene and reducing the haze of the modified polypropylene.

[0075] As the addition amount of methanol increases continuously, the flexural modulus of the modified polypropylene shows a trend of first rising and then leveling off, and the haze shows a trend of first decreasing and then leveling off. This may be because as the addition amount of methanol increases continuously, it is convenient for the reaction between hexahydrophthalic acid and calcium hydroxide, and it can also absorb the water molecules generated by the reaction, thereby improving the flexural modulus of the modified polypropylene and reducing the haze.

[0076] In addition, by comparing Examples 1-5, it is found that Example 1 has the best comprehensive performance. Therefore, Example 1 is preferred.

[0077] Examples 6-9

[0078] Based on the preparation method of Example 1, in Examples 6-9, methanol was adjusted to other alcohols, and the specific adjustments are shown in Table 2.

[0079] The calcium hexahydrophthalate of Examples 6-9 was subjected to the above performance tests, and the test results are shown in Table 2.

[0080] Table 2 Alcohol types and performance test table of Example 1 and Examples 6-9

[0081] Project Example 1 Example 6 Example 7 Example 8 Example 9 Alcohol Type Methanol Ethanol Ethylene Glycol Propylene Glycol Glycerol Flexural Modulus / MPa 1151 1136 1133 1123 1119 Haze / % 15.6 16.9 17.2 18.5 18.7

[0082] Referring to Table 2, by comparing Example 1 and Examples 6-9, it can be seen that methanol, ethanol, ethylene glycol, propylene glycol, and glycerol can all be used in this application. The main reason is that they all contain a hydroxyl (-OH) functional group, which enables them to form hydrogen bonds with water molecules, thereby showing strong water affinity. Comparatively, methanol has the best effect.

[0083] Examples 10-13

[0084] Based on the preparation method of Example 1, in Examples 10-13, the time of the acid-base neutralization reaction was adjusted, and the specific adjustments are shown in Table 3.

[0085] The calcium hexahydrophthalate of Examples 10-13 was subjected to the above performance tests, and the test results are shown in Table 3.

[0086] Table 3 Time and Performance Detection Table of Acid-Base Neutralization Reactions in Example 1 and Examples 10 - 13

[0087] Project Example 1 Example 10 Example 11 Example 12 Example 13 Reaction Time / h 2 0.5 1 1.5 2.5 Flexural Modulus / MPa 1151 1105 1118 1141 1151 Haze / % 15.6 20.9 19.4 16.1 15.5

[0088] Referring to Table 3, by comparing Example 1 with Examples 10 - 13, it can be seen that as the time of the acid-base neutralization reaction continuously increases, the flexural modulus shows a trend of first increasing and then leveling off, and the haze shows a trend of first decreasing and then leveling off. This may be because as the time of the acid-base neutralization reaction continuously increases, the reaction between hexahydrophthalic acid and calcium hydroxide becomes more and more complete, thereby increasing the flexural modulus of the modified polypropylene and reducing the haze of the modified polypropylene.

[0089] Examples 14 - 18

[0090] On the basis of the preparation method of Example 1, after calcium hydroxide was added to the hexahydrophthalic acid-alcohol solution and reacted for 0.6 h, 3 g of zeolite was added to the hexahydrophthalic acid-alcohol solution, and the other conditions remained unchanged.

[0091] On the basis of the preparation method of Example 14, for Examples 15 - 18, the addition amount of zeolite was adjusted, and the specific adjustment is shown in Table 4.

[0092] The calcium hexahydrophthalates of Examples 14 - 18 were subjected to the above performance tests, and the test results are shown in Table 4 respectively.

[0093] Table 4 Addition Amount and Performance Detection Table of Zeolite in Example 1 and Examples 14 - 18

[0094] Project Example 1 Example 14 Example 15 Example 16 Example 17 Example 18 Zeolite / g / 3 0.5 1 2 3.5 Flexural Modulus / MPa 1151 1181 1154 1161 1173 1182 Haze / % 15.6 10.4 15.4 14.2 12.6 10.4

[0095] Referring to Table 4, by comparing Example 1 with Examples 14 - 18, it can be seen that after adding zeolite, it can further adsorb trace water molecules in the reaction system, thereby further increasing the flexural modulus of the modified polypropylene and reducing the haze of the modified polypropylene.

[0096] As the addition amount of zeolite continuously increases, the flexural modulus shows a trend of first increasing and then leveling off, and the haze shows a trend of first decreasing and then leveling off. This may be because as the addition amount of zeolite continuously increases, compared with alcohol liquids, it has higher water adsorption, can further adsorb the water molecules generated by the acid-base neutralization reaction, reduce the content of free water in the solution, thereby improving the performance of calcium hexahydrophthalate, and thus increasing the flexural modulus of the modified polypropylene and reducing the haze of the modified polypropylene.

[0097] Examples 19 - 20

[0098] Examples 19 - 20 Based on the preparation method of Example 14, the zeolite was replaced with other adsorbents, and the other conditions remained unchanged.

[0099] Perform the above performance tests on the calcium hexahydrophthalate of Examples 19 - 20. The test results are shown in Table 5 respectively.

[0100] Table 5 Adsorbent types and performance test tables of Example 1, Example 14, and Examples 19 - 20

[0101] Project Example 1 Example 14 Example 19 Example 20 Adsorbent Type / Zeolite Activated Carbon Silica Gel Flexural Modulus / MPa 1151 1181 1178 1176 Haze / % 15.6 10.4 10.6 10.7

[0102] Referring to Table 5, by comparing Example 1, Example 14, and Examples 19 - 20, it can be seen that after adding activated carbon and silica gel, the flexural modulus of the modified polypropylene can be effectively increased and the haze of the modified polypropylene can be reduced.

[0103] Examples 21 - 24

[0104] Based on the preparation method of Example 14, the time for adding zeolite in Examples 21 - 24 was adjusted. The specific adjustment is shown in Table 6.

[0105] Perform the above performance tests on the calcium hexahydrophthalate of Examples 21 - 24. The test results are shown in Table 6 respectively.

[0106] Table 6 The time for adding zeolite and performance test tables of Example 1, Example 14, and Examples 21 - 24

[0107] Project Example 1 Example 14 Example 21 Example 22 Example 23 Example 24 Addition Time / h / 0.6 0.3 0.4 0.8 1 Flexural Modulus / MPa 1151 1181 1159 1169 1173 1164 Haze / % 15.6 10.4 14.7 13.5 12.7 14.1

[0108] Referring to Table 6, by comparing Example 1, Example 14, and Examples 21 - 24, it can be seen that as the time for adding zeolite increases, the flexural modulus shows a trend of first increasing and then decreasing, and the haze shows a trend of first decreasing and then increasing. This may be because as the time for adding zeolite increases, a large amount of reaction between hexahydrophthalic acid and calcium hydroxide starts. At this time, a large number of generated water molecules are adsorbed by methanol, and a small amount of water molecules are adsorbed by zeolite. The bound water content of the prepared calcium hexahydrophthalate is less, thus increasing the flexural modulus of the modified polypropylene and reducing the haze of the modified polypropylene. When the time for adding zeolite exceeds a certain range, calcium hydroxide reacts fully with hexahydrophthalic acid and generates a large amount of water molecules. At this time, the free water molecules in the solution may have formed a certain concentration gradient or distribution state. When the adsorbent is added at this time, although some free water molecules can be adsorbed, it may not be able to completely remove all the water. The bound water content of calcium hexahydrophthalate is not further improved, thus reducing the flexural modulus of the modified polypropylene and increasing the haze of the modified polypropylene.

[0109] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A method for preparing calcium hexahydrophthalate, characterized in that, It includes the following steps: Dissolution: Dissolve hexahydrophthalic acid in alcohol to obtain a hexahydrophthalic acid-alcohol solution; the mass ratio of the hexahydrophthalic acid to the alcohol is 1:6-10, and the alcohol includes at least one of methanol, ethanol, ethylene glycol, propylene glycol, and glycerol; Acid-base neutralization: Add calcium hydroxide to the hexahydrophthalic acid-alcohol solution for reaction. After reacting for 0.4-0.8 h, add an adsorbent to the hexahydrophthalic acid-alcohol solution, filter and dry to obtain calcium hexahydrophthalate; the adsorbent includes zeolite, activated carbon, and silica gel.

2. The preparation method of calcium hexahydrophthalate according to claim 1, characterized in that: The alcohol is methanol.

3. The preparation method of calcium hexahydrophthalate according to claim 1, characterized in that: In the step of acid-base neutralization, the reaction time is 1-2 h.

4. The preparation method of calcium hexahydrophthalate according to claim 1, characterized in that: The mass ratio of the hexahydrophthalic acid to the adsorbent is 1:0.1-0.3.