Calcium hexahydrophthalate as well as preparation method and application thereof

Abstract

The invention relates to the field of nucleating agent material preparation, in particular to calcium hexahydrophthalate as well as a preparation method and application thereof. The invention relates to a preparation method of calcium hexahydrophthalate, which comprises the following steps: dissolving: dissolving hexahydrophthalic acid in alcohol to obtain a hexahydrophthalic acid-alcohol solution; and acid-base neutralization: adding calcium hydroxide into the hexahydrophthalic acid-alcohol solution to react, filtering, and drying to obtain the hexahydrophthalic acid calcium. According to the invention, hexahydrophthalic acid and calcium hydroxide are subjected to an acid-base neutralization reaction in an alcohol liquid, and most of generated water molecules are adsorbed by the alcohol liquid, so that the water molecules are difficult to combine with calcium hexahydrophthalate to form a crystalline hydrate. And meanwhile, only alcohol liquid and trace free water need to be removed during drying, so that the energy consumption and the time cost are reduced.

Description

Technical Field

[0001] The present application relates to the field of preparation of nucleating agent materials, and in particular to calcium hexahydrophthalate and a preparation method and application thereof. Background Art

[0002] Calcium hexahydrophthalate is a commonly used rigidity-enhancing nucleating agent product, which can significantly increase the bending modulus of polypropylene products, reduce haze, and 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 crystal water is present, 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. Hexahydrophthalic anhydride is put into water for hydrolysis to generate hexahydrophthalic acid, and then calcium hydroxide is put into it to generate an acid-base neutralization reaction to obtain calcium hexahydrophthalate. Because the reaction is carried out in an aqueous solution system, water is produced by acid-base neutralization at the same time, and the generated calcium hexahydrophthalate molecules all contain one crystal water. The crystal water is difficult to remove during the drying process, the cost is high, and it is difficult to remove thoroughly, which ultimately affects the product application effect. Summary of the invention

[0003] In order to solve the problem that the preparation of calcium hexahydrophthalate in the aqueous solution system in the prior art causes the final product to combine with crystal water, thereby affecting the effect of calcium hexahydrophthalate as a nucleating agent. The present application provides a preparation method of calcium hexahydrophthalate, which is carried out in an alcohol solution system, and utilizes the strong adsorption of alcohol to water molecules to make it difficult for calcium hexahydrophthalate to combine with water molecules, thereby improving the performance of the final product, and being able to better improve the bending modulus of polypropylene and reduce the haze.

[0004] In the first aspect, the present application provides a method for preparing calcium hexahydrophthalate, using the following technical solution: A method for preparing calcium hexahydrophthalate comprises the following steps: Dissolution: dissolving hexahydrophthalic acid in alcohol to obtain a hexahydrophthalic acid-alcohol solution; Acid-base neutralization: adding calcium hydroxide into the hexahydrophthalic acid-alcohol solution for reaction, filtering and drying to obtain calcium hexahydrophthalate.

[0005] By adopting the above technical scheme, a uniform hexahydrophthalic acid-alcohol solution can be formed by dissolving hexahydrophthalic acid in alcohol, which helps the uniform dispersion of hexahydrophthalic acid and the full contact of 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 generate calcium hexahydrophthalate and water. In the conventional process, the generated calcium hexahydrophthalate usually combines with water molecules to form a crystalline hydrate. In the present application, since alcohol liquids have a strong affinity for water molecules, most of the water molecules are adsorbed by alcohol liquids, thereby reducing the chance of calcium hexahydrophthalate combining with water molecules. This helps to obtain anhydrous or less water calcium hexahydrophthalate.

[0006] In traditional preparation methods, the drying process may require the removal of a large amount of water, which usually takes a long time and consumes a lot of energy. In this scheme, due to the use of alcohol solvents and the adsorption of water molecules, only alcohol liquid and trace amounts of free water need to be removed during the drying process. This greatly simplifies the drying process and reduces energy consumption and time costs.

[0007] In the present application, hexahydrophthalic acid and calcium hydroxide are subjected to an acid-base neutralization reaction in an alcohol liquid, and most of the generated water molecules are adsorbed by the alcohol liquid, and thus are difficult to combine with calcium hexahydrophthalate to form a crystalline hydrate. At the same time, during drying, only the alcohol liquid and a trace amount of free water need to be removed, thereby reducing energy consumption and time costs.

[0008] Preferably, in the dissolving step, the alcohol includes at least one of methanol, ethanol, ethylene glycol, propylene glycol and glycerol.

[0009] Preferably, the alcohol is methanol.

[0010] By adopting the above technical solution, methanol, ethanol, ethylene glycol, propylene glycol and glycerol all contain hydroxyl (-OH) functional groups, which enable them to form hydrogen bonds with water molecules, thereby showing strong water affinity.

[0011] Among them, methanol has a smaller molecular structure and its hydroxyl functional group is relatively exposed, so the interaction between methanol and water molecules is stronger and it is easy to form hydrogen bonds, thus showing stronger adsorption. Ethanol has a relatively long molecular chain and the position of the hydroxyl functional group in the molecule is relatively "hidden", which may cause the interaction between ethanol and water molecules to be slightly weaker than that of methanol. Therefore, from the perspective of adsorption, ethanol may not be as strong as methanol.

[0012] In addition, ethylene glycol, propylene glycol and glycerol have high viscosity, and it is not as convenient to stir hexahydrophthalic acid and calcium hydroxide in them as methanol. Therefore, methanol is a better choice in comparison.

[0013] Preferably, the mass ratio of hexahydrophthalic acid to alcohol is 1:6-10.

[0014] By adopting the above technical scheme, 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, so that the reaction rate and efficiency are reduced. The shortage of alcohol may reduce the fluidity of the reaction system and increase the difficulty of stirring and mixing. This may cause uneven reaction and affect the quality and uniformity of the product. When the content of alcohol is too high, hexahydrophthalic acid and calcium hydroxide can already fully react.

[0015] Preferably, in the acid-base neutralization step, the reaction time is 1-2 hours.

[0016] By adopting the above technical scheme, 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, stirring degree, etc. Controlling the reaction time to 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 and hexahydrophthalic acid react fully to generate the required calcium hexahydrophthalate. Too short a reaction time may lead to incomplete reaction, while too long a reaction time is unnecessary.

[0017] Preferably, the preparation method of calcium hexahydrophthalate further comprises adding an adsorbent to the hexahydrophthalic acid-alcohol solution, wherein the adsorbent comprises zeolite, activated carbon and silica gel.

[0018] By adopting the above technical solution, zeolite, activated carbon and silica gel, these adsorbents have higher water adsorption than alcohol liquids, can further adsorb water molecules produced by acid-base neutralization reactions, reduce the content of free water in the solution, and thus improve the quality of calcium hexahydrophthalate.

[0019] Preferably, the mass ratio of hexahydrophthalic acid to adsorbent is 1:0.1-0.3.

[0020] 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 produced 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 the performance of calcium hexahydrophthalate is difficult to further increase, and there is no need to continue to add the content of the adsorbent.

[0021] Preferably, after calcium hydroxide is added to the hexahydrophthalic acid-alcohol solution to react for 0.4-0.8h, an adsorbent is added to the hexahydrophthalic acid-alcohol solution.

[0022] By adopting the above technical solution, the adsorbent has a greater adsorption capacity for water than for alcohol liquids. However, if the adsorbent is added to the hexahydrophthalic acid-alcohol solution too early, that is, before the calcium hydroxide has fully reacted, the adsorbent may preferentially adsorb the alcohol liquid in the solution. Once the adsorbent is occupied by the alcohol liquid, its adsorption capacity will be greatly reduced, and it will be difficult to effectively adsorb the water molecules generated by the subsequent reaction.

[0023] On the contrary, if the adsorbent is added too late, that is, after the calcium hydroxide and hexahydrophthalic acid react completely and generate a large number of water molecules, the adsorbent may not be able to play an effective adsorption role. This is because the free water molecules in the solution may have formed a certain concentration gradient or distribution state, and some water molecules may have been combined with the product or other components. At this time, although the adsorbent can adsorb some free water molecules, it may not be able to completely remove all water, thus affecting the drying effect and final quality of the product.

[0024] In a second aspect, the present application provides a calcium hexahydrophthalate, which adopts the following technical solution: A calcium hexahydrophthalate is prepared by the preparation method of calcium hexahydrophthalate.

[0025] In a third aspect, the present application provides an application of calcium hexahydrophthalate, using the following technical solution: An application of calcium hexahydrophthalate, comprising the application of the calcium hexahydrophthalate in polypropylene.

[0026] By adopting the above technical solution, the little bound water contained in calcium hexahydrophthalate during the preparation process helps it to better play the role of a nucleating agent. By adding calcium hexahydrophthalate, the bending modulus of polypropylene can be effectively improved. Adding calcium hexahydrophthalate to polypropylene can also effectively reduce its haze and improve transparency.

[0027] In summary, this application has the following beneficial effects: 1. Since the present application conducts 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, and thus are difficult to combine with calcium hexahydrophthalate to form a crystalline hydrate. At the same time, during drying, only the alcohol liquid and a trace amount of free water need to be removed, which reduces energy consumption and time costs; 2. The alcohol used in this application is methanol, which has stronger adsorption to water molecules, lower viscosity, and is easier to stir than other alcohols; 3. This application may also add adsorbents such as zeolite, activated carbon and silica gel to further absorb water molecules and further improve the performance of calcium hexahydrophthalate. DETAILED DESCRIPTION

[0028] The raw materials in this application include the following parts: Hexahydrophthalic acid: a commercially available product with CAS number 610-09-3; Methanol: a commercial product with CAS number 67-56-1 was used; Ethanol: a commercially available product with CAS number 64-17-5 was used; Ethylene glycol: a commercial product with CAS number 107-21-1 is used; Propylene glycol: a commercially available product with CAS number 57-55-6; Glycerol: a commercial product with CAS number 56-81-5 was used; Calcium hydroxide: a commercially available product with CAS number 13025-62-0; Zeolite: a commercially available product with CAS No. 1318-02-1 was used; Activated carbon: a commercially available product with CAS number 64365-11-3; Silica gel: a commercially available product with CAS number 112926-00-8; The present application is further described in detail below in conjunction with embodiments and comparative examples. Example 1

[0029] A method for preparing calcium hexahydrophthalate comprises the following steps: Dissolution: Dissolve 10 g of hexahydrophthalic acid in 90 g of methanol to obtain a hexahydrophthalic acid-alcohol solution; Acid-base neutralization: Add 25 g of calcium hydroxide into a hexahydrophthalic acid-alcohol solution for reaction for 2 h. After filtering, dry at 120° C. for 0.5 h to obtain calcium hexahydrophthalate.

[0030] Embodiment 2-5 In Example 2-5, based on the preparation method of Example 1, the amount of methanol added was adjusted, and the specific adjustment is shown in Table 1.

[0031] Comparative Example 1-2 Comparative Example 1 A method for preparing calcium hexahydrophthalate comprises the following steps: Hydrolysis: Dissolve 10 g of hexahydrophthalic acid in 100 g of water to obtain a hexahydrophthalic acid solution; Acid-base neutralization: Add 25 g of calcium hydroxide into the hexahydrophthalic acid solution for reaction for 2 h. After filtering, dry at 120° C. for 0.5 h to obtain calcium hexahydrophthalate.

[0032] Comparative Example 2 is based on the preparation method of Example 1, except that the drying time is extended from 0.5 h to 3 h, and the other conditions remain unchanged.

[0033] Table 1 The amount of methanol added and the performance test table of Examples 1-5 and Comparative Examples 1-2 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 Performance testing After the polypropylene was modified with the hexahydrophthalic acid of Examples 1-5 and Comparative Examples 1-2, the following performance tests were performed. The test results are shown in Table 1.

[0034] A method for preparing modified polypropylene comprises the following steps: (1) Mixing 1000g of polypropylene and 5g of calcium hexahydrophthalate were put into an internal mixer, mixed for 10min, and discharged at 65°C to obtain a mixed rubber; (2) Opening of Refining The mixed rubber was thinned 3 times, and the mixture was smelted for 5 minutes until it was uniform, and the master film was obtained by cutting. (3) Granulation Then the masterbatch is placed in a granulator and granulated at a temperature of 50°C to obtain modified polypropylene.

[0035] 1. Flexural modulus The modified polypropylene was tested according to the standard of GB / T9341-2008.

[0036] 2. Haze The modified polypropylene was tested according to the standard of GB / T2410-2008 (thickness 1mm).

[0037] Referring to Table 1, it can be seen from the comparison between Examples 1-5 and Comparative Examples 1-2 that, compared with Comparative Examples 1-2, the bending 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. In particular, even if the drying time is longer in the later stage, the effect of Comparative Example 2 is not as good as that of Examples 1-5. This indicates that the preparation of calcium hexahydrophthalate in methanol has less crystal water, and calcium hexahydrophthalate can better play the role of a nucleating agent, thereby improving the bending modulus of the modified polypropylene and reducing the haze of the modified polypropylene.

[0038] As the amount of methanol added continues to increase, the bending modulus of the modified polypropylene shows a trend of first increasing and then tending to a stable state, and the haze shows a trend of first decreasing and then tending to a stable state. This may be because the increasing amount of methanol added facilitates the mixing reaction of hexahydrophthalic acid and calcium hydroxide, and can also absorb the water molecules produced by the reaction, thereby increasing the bending modulus of the modified polypropylene and reducing the haze.

[0039] In addition, by comparing Examples 1-5, it is found that Example 1 has the best comprehensive performance, so Example 1 is preferred.

[0040] Embodiment 6-9 In Examples 6-9, based on the preparation method of Example 1, methanol is adjusted to other alcohols. The specific adjustments are shown in Table 2.

[0041] The calcium hexahydrophthalate of Examples 6-9 was subjected to the above performance tests, and the test results are shown in Table 2.

[0042] Table 2 Alcohol types and performance test table of Example 1 and Examples 6-9 project Example 1 Example 6 Example 7 Example 8 Example 9 Alcohol Type Methanol Ethanol Ethylene glycol Propylene glycol glycerin Flexural modulus / MPa 1151 1136 1133 1123 1119 Haze / % 15.6 16.9 17.2 18.5 18.7 Referring to Table 2, by comparing Example 1 with Examples 6-9, it can be seen that methanol, ethanol, ethylene glycol, propylene glycol and glycerol can all be used in this application, mainly because they all contain hydroxyl (-OH) functional groups, which enable them to form hydrogen bonds with water molecules, thereby showing strong water affinity. In comparison, methanol has the best effect.

[0043] Examples 10-13 In Examples 10-13, based on the preparation method of Example 1, the time of the acid-base neutralization reaction was adjusted. The specific adjustments are shown in Table 3.

[0044] The calcium hexahydrophthalate of Examples 10-13 was subjected to the above performance tests, and the test results are shown in Table 3.

[0045] Table 3 Time and performance test table of acid-base neutralization reaction of Example 1 and Examples 10-13 project Example 1 Example 10 Embodiment 11 Example 12 Embodiment 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 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 continues to increase, the flexural modulus shows a trend of first increasing and then tending to be stable, and the haze shows a trend of first decreasing and then tending to be stable. This may be because as the time of the acid-base neutralization reaction continues to increase, the reaction of 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.

[0046] Examples 14-18 Example 14 Based on the preparation method of Example 1, after calcium hydroxide is added to the hexahydrophthalic acid-alcohol solution to react for 0.6h, 3g of zeolite is added to the hexahydrophthalic acid-alcohol solution, and the other conditions remain unchanged.

[0047] In Examples 15-18, based on the preparation method of Example 14, the amount of zeolite added was adjusted. The specific adjustments are shown in Table 4.

[0048] The calcium hexahydrophthalate of Examples 14-18 was subjected to the above performance tests, and the test results are shown in Table 4 respectively.

[0049] Table 4 The addition amount and performance test table of zeolite in Example 1 and Examples 14-18 project Example 1 Embodiment 14 Embodiment 15 Example 16 Embodiment 17 Embodiment 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 Referring to Table 4, by comparing Example 1 with Examples 14-18, it can be seen that the addition of zeolite can further adsorb trace water molecules in the reaction system, thereby further increasing the bending modulus of the modified polypropylene and reducing the haze of the modified polypropylene.

[0050] As the amount of zeolite added continues to increase, the bending modulus shows a trend of first increasing and then tending to a stable state, and the haze shows a trend of first decreasing and then tending to a stable state. This may be because as the amount of zeolite added continues to increase, it has a higher water adsorption capacity than alcohol liquids, and can further adsorb water molecules produced by the acid-base neutralization reaction and reduce the content of free water in the solution, thereby improving the performance of calcium hexahydrophthalate, thereby increasing the bending modulus of modified polypropylene and reducing the haze of modified polypropylene.

[0051] Examples 19-20 Examples 19-20 are based on the preparation method of Example 14, except that the zeolite is replaced with other adsorbents, and the other conditions remain unchanged.

[0052] The calcium hexahydrophthalate of Examples 19-20 was subjected to the above performance tests, and the test results are shown in Table 5.

[0053] Table 5 Adsorbent types and performance test table of Example 1, Example 14 and Examples 19-20 project Example 1 Embodiment 14 Embodiment 19 Embodiment 20 Adsorbent type / Zeolite Activated carbon Silicone Flexural modulus / MPa 1151 1181 1178 1176 Haze / % 15.6 10.4 10.6 10.7 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 bending modulus of the modified polypropylene can also be effectively improved and the haze of the modified polypropylene can be reduced.

[0054] Examples 21-24 In Examples 21-24, based on the preparation method of Example 14, the time for adding zeolite is adjusted. The specific adjustments are shown in Table 6.

[0055] The calcium hexahydrophthalate of Examples 21-24 was subjected to the above performance tests, and the test results are shown in Table 6 respectively.

[0056] Table 6 Time and performance test table of adding zeolite in Example 1, Example 14 and Examples 21-24 project Example 1 Embodiment 14 Embodiment 21 Embodiment 22 Embodiment 23 Embodiment 24 Add 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 Referring to Table 6, it can be seen from the comparison of Example 1, Example 14 and Examples 21-24 that as the time of adding zeolite increases, the bending 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 of adding zeolite increases, hexahydrophthalic acid and calcium hydroxide begin to react in large quantities. At this time, a large amount of water molecules generated 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, thereby increasing the bending modulus of the modified polypropylene and reducing the haze of the modified polypropylene; when the time of 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. At this time, although the adsorbent is added, a part of the free water molecules can be adsorbed, all the water may not be completely removed, and the bound water content of calcium hexahydrophthalate is not further improved, thereby reducing the bending modulus of the modified polypropylene and increasing the haze of the modified polypropylene.

[0057] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed. However, as long as it is within the scope of the claims of the present application, it shall be protected by the patent law.

Claims

1. A method for preparing calcium hexahydrophthalate, characterized in that: The following steps are involved: Dissolution: dissolving hexahydrophthalic acid in alcohol to obtain a hexahydrophthalic acid-alcohol solution; Acid-base neutralization: adding calcium hydroxide into the hexahydrophthalic acid-alcohol solution for reaction, filtering and drying to obtain calcium hexahydrophthalate.

2. The preparation method of calcium hexahydrophthalate according to claim 1, characterized in that: In the dissolving step, the alcohol includes at least one of methanol, ethanol, ethylene glycol, propylene glycol and glycerol.

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

4. The method for preparing calcium hexahydrophthalate according to claim 1, wherein: The mass ratio of the hexahydrophthalic acid to the alcohol is 1:6-10.

5. The method for preparing calcium hexahydrophthalate according to claim 1, wherein: In the acid-base neutralization step, the reaction time is 1-2 hours.

6. The method for preparing calcium hexahydrophthalate according to claim 1, wherein: The method also includes adding an adsorbent to the hexahydrophthalic acid-alcohol solution, wherein the adsorbent includes zeolite, activated carbon and silica gel.

7. The method for preparing calcium hexahydrophthalate according to claim 6, wherein: The mass ratio of the hexahydrophthalic acid to the adsorbent is 1:0.1-0.

3.

8. The method for preparing calcium hexahydrophthalate according to claim 6, wherein: After calcium hydroxide is added to the hexahydrophthalic acid-alcohol solution to react for 0.4-0.8h, an adsorbent is added to the hexahydrophthalic acid-alcohol solution.

9. A calcium hexahydrophthalate, characterized in that: The calcium hexahydrophthalate is prepared by the preparation method of calcium hexahydrophthalate according to any one of claims 1 to 8.

10. An application of calcium hexahydrophthalate, characterized in that: The use of calcium hexahydrophthalate in polypropylene as claimed in claim 9.