Method for preparing modified magnesium hydroxide by using salt-making mother liquor and flame-retardant material

Abstract

The invention relates to the technical field of flame retardants, in particular to a method for preparing modified magnesium hydroxide by using salt-making mother liquor and a flame-retardant material.The flame-retardant material is prepared from modified magnesium hydroxide, hexa (4-boronic acid phenoxy)-cyclophosphazene and ethylene-vinyl acetate copolymer according to the set proportion of (1-100): (1-100): 100, and the flame-retardant material is prepared from modified magnesium hydroxide, hexa (4-boronic acid phenoxy)-cyclophosphazene and ethylene-vinyl acetate copolymer according to the set proportion of (1-100): (1-100): 100. The method comprises the following steps: adding a precipitator into a refined solution to obtain mixed slurry; and adding a modifier, which is an ethanol solution of cetyltrimethylammonium bromide, into the mixed slurry, filtering by using a filter to obtain a solid product, and drying the solid product to obtain the modified magnesium hydroxide. The modified magnesium hydroxide disclosed by the invention is oleophylic and hydrophobic and has a high activation index, so that the dispersity and compatibility of the modified magnesium hydroxide with a high-molecular polymer are enhanced; meanwhile, the flame-retardant material disclosed by the invention has good performance in the aspect of oxygen index.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardants, and in particular to a method for preparing modified magnesium hydroxide by utilizing salt-making mother liquor and a flame retardant material. Background Art

[0002] As an important inorganic flame retardant, magnesium hydroxide generates water after heat treatment without generating any corrosive or harmful substances. In addition, magnesium hydroxide can absorb heat, which can reduce the temperature of the filling material and will not pollute the environment. Therefore, it is widely used in high molecular polymers such as polyvinyl chloride, polypropylene and unsaturated resins. It has good effects in flame retardancy and smoke suppression and is widely regarded as an environmentally friendly green flame retardant.

[0003] However, magnesium hydroxide has high polarity and a large amount is added to the material, which results in it being unable to be completely evenly dispersed and compatible in the polymer. Magnesium hydroxide needs to be modified to enhance its dispersibility and compatibility with the polymer.

[0004] The LOI value of the flame retardant material prepared with magnesium hydroxide alone as a flame retardant is relatively low. When in some high-temperature fire environments, the flame retardant properties of the flame retardant material are greatly reduced. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the related art. To this end, the present invention provides a method for preparing modified magnesium hydroxide using salt production mother liquor and a flame retardant material, wherein the modified magnesium hydroxide is lipophilic and hydrophobic, and its dispersibility and compatibility with high molecular polymers are enhanced. At the same time, the flame retardant material of the present invention has good oxygen index performance and enhanced flame retardant effect.

[0006] The present invention provides a method for preparing modified magnesium hydroxide by using salt-making mother liquor, comprising the following steps: The mother liquor of salt production is filtered by a nanofiltration membrane to obtain a refined liquid; Taking a first set amount of refined liquid and adding a second set amount of precipitant thereto, stirring at a set temperature for a first set time to obtain a mixed slurry; A third set amount of a modifier is added to the mixed slurry, wherein the modifier is an ethanol solution of hexadecyltrimethylammonium bromide, and the mixture is stirred at a set temperature for a second set time, and then filtered using a filter to obtain a solid product, and the solid product is dried to obtain modified magnesium hydroxide.

[0007] A further improvement of the method for preparing modified magnesium hydroxide using salt production mother liquor of the present invention is that before filtering the salt production mother liquor using a nanofiltration membrane, the method further comprises the following steps: The salt-making mother liquor is diluted 10 times by volume to obtain a diluted solution, and the diluted solution is filtered using a nanofiltration membrane to obtain a refined solution.

[0008] A further improvement of the method for preparing modified magnesium hydroxide using salt-making mother liquor of the present invention is that the precipitant is a sodium hydroxide aqueous solution.

[0009] A further improvement of the method for preparing modified magnesium hydroxide using salt-making mother liquor of the present invention is that the mass percentage concentration of the sodium hydroxide aqueous solution is 40%.

[0010] A further improvement of the method for preparing modified magnesium hydroxide using salt production mother liquor of the present invention is that the first set amount is 100 mL and the second set amount is 30 mL.

[0011] A further improvement of the method for preparing modified magnesium hydroxide using salt production mother liquor of the present invention is that the concentration of the modifier is 0.55 mol / L, and the third set amount is 2%, 4%, and 6% of the first set amount.

[0012] A further improvement of the method for preparing modified magnesium hydroxide using salt production mother liquor of the present invention is that the set temperature is 50°C.

[0013] A further improvement of the method for preparing modified magnesium hydroxide using salt production mother liquor of the present invention is that the first set time is 1 hour.

[0014] A further improvement of the method for preparing modified magnesium hydroxide using salt production mother liquor of the present invention is that the second set time is 0.5h~1.5h.

[0015] A further improvement of the method for preparing modified magnesium hydroxide using salt production mother liquor of the present invention is that the filter is a plate-and-frame filter.

[0016] The present invention also provides a flame retardant material, using the modified magnesium hydroxide prepared by the method as described above, comprising: The flame retardant material is prepared from modified magnesium hydroxide, hexa(4-boric acid phenoxy)-cyclophosphazene and ethylene-vinyl acetate copolymer in a set ratio, wherein the set ratio is (1-100): (1-100): 100, wherein the ratio of the sum of the proportions of modified magnesium hydroxide and hexa(4-boric acid phenoxy)-cyclophosphazene to the ethylene-vinyl acetate copolymer is 1:1; The modified magnesium hydroxide, hexa(4-boric acid phenoxy)-cyclophosphazene and ethylene-vinyl acetate copolymer are added into the torque rheometer according to a set ratio for mixing to obtain a mixed product, and the mixed product is vulcanized to obtain the flame retardant material.

[0017] The above one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: (1) The present invention uses salt production mother liquor as raw material, which has a wide source of raw materials and low production cost.

[0018] (2) The present invention uses nanofiltration membrane to filter the salt production mother liquor to obtain Mg-rich 2+ The refined liquid is used to prepare magnesium hydroxide with high purity, which can reach 99%. The high-purity magnesium hydroxide is then modified to obtain modified magnesium hydroxide with a high activation index.

[0019] (3) The activation index of the modified magnesium hydroxide prepared by the present invention is high, indicating that the modifier Grafted onto the surface of magnesium hydroxide, with its long alkyl hydrophobic chains facing outward to prevent The electrostatic repulsion between the magnesium hydroxide and the modifier is eliminated. At the same time, the molecular layer formed by the modifier wraps the magnesium hydroxide almost completely. At this time, the dispersibility and compatibility of the modified magnesium hydroxide are greatly improved, and the mixing effect with high molecular polymers is better.

[0020] The flame retardant material prepared by the invention has good flame retardant effect, and the raw material source is the modified magnesium hydroxide prepared from salt production mother liquor, thereby reducing the cost of the flame retardant material.

[0021] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 The present invention provides a schematic diagram of a process for preparing modified magnesium hydroxide using a salt-making mother liquor. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0025] Combine the following Figure 1 A method for preparing modified magnesium hydroxide using salt-making mother liquor of the present invention is described, comprising the following steps: The mother liquor of salt production is filtered by a nanofiltration membrane to obtain a refined liquid; Taking a first set amount of refined liquid and adding a second set amount of precipitant thereto, stirring at a set temperature for a first set time to obtain a mixed slurry; A third set amount of a modifier is added to the mixed slurry, wherein the modifier is an ethanol solution of hexadecyltrimethylammonium bromide, and the mixture is stirred at a set temperature for a second set time to obtain a slurry containing modified magnesium hydroxide, and then filtered using a filter to obtain a solid product, and the solid product is dried to obtain modified magnesium hydroxide.

[0026] In a preferred embodiment of the method for preparing modified magnesium hydroxide using salt production mother liquor of the present invention, before filtering the salt production mother liquor using a nanofiltration membrane, the method further includes the following steps: The salt-making mother liquor was diluted 10 times by volume to obtain a diluted solution, and the diluted solution was filtered using a nanofiltration membrane to obtain a refined solution.

[0027] Preferably, the precipitant is an aqueous solution of sodium hydroxide, and the mass percent concentration of the aqueous solution of sodium hydroxide is 40%.

[0028] It should be noted that the precipitant may also be an aqueous solution of potassium hydroxide.

[0029] Specifically, the first set amount is 100 mL, and the second set amount is 30 mL.

[0030] Specifically, a 0.55 mol / L ethanol solution of hexadecyltrimethylammonium bromide is prepared, and the third set amount is 2%, 4%, and 6% of the first set amount.

[0031] Specifically, the temperature was set to 50°C.

[0032] Specifically, the first set time is 1 hour.

[0033] Specifically, the second set time is 0.5h~1.5h.

[0034] Specifically, the filter is a plate and frame filter.

[0035] Examples 1 to 5 are provided below to prepare modified magnesium hydroxide.

[0036] Example 1 Take 100 mL of the refined liquid, add 30 mL of a 40% by mass concentration sodium hydroxide aqueous solution, stir at 50 ° C for 1 hour, then add a modifier, the modifier is a 0.55 mol / L ethanol solution of hexadecyltrimethylammonium bromide, and the amount of the modifier added is 2% of the volume of the refined liquid. Continue stirring for 0.5 h, filter through a plate and frame filter, and then dry to obtain modified magnesium hydroxide.

[0037] Example 2 Take 100 mL of the refined liquid, add 30 mL of a 40% by mass concentration sodium hydroxide aqueous solution, stir at 50 ° C for 1 hour, then add a modifier, the modifier is a 0.55 mol / L ethanol solution of hexadecyltrimethylammonium bromide, and the amount of the modifier added is 4% of the volume of the refined liquid. Continue stirring for 0.5 h, filter through a plate and frame filter, and then dry to obtain modified magnesium hydroxide.

[0038] Example 3 Take 100 mL of the refined liquid, add 30 mL of a 40% by mass concentration sodium hydroxide aqueous solution, stir at 50 ° C for 1 hour, then add a modifier, the modifier is a 0.55 mol / L ethanol solution of hexadecyltrimethylammonium bromide, and the amount of the modifier added is 6% of the volume of the refined liquid. Continue stirring for 0.5 h, filter through a plate and frame filter, and then dry to obtain modified magnesium hydroxide.

[0039] Example 4 Take 100 mL of the refined liquid, add 30 mL of a 40% by mass concentration sodium hydroxide aqueous solution, stir at 50 ° C for 1 hour, then add a modifier, the modifier is a 0.55 mol / L ethanol solution of hexadecyltrimethylammonium bromide, and the amount of the modifier added is 4% of the volume of the refined liquid. Continue stirring for 1 hour, filter through a plate and frame filter, and then dry to obtain modified magnesium hydroxide.

[0040] Example 5 Take 100 mL of the refined liquid, add 30 mL of a 40% by mass concentration of sodium hydroxide aqueous solution, stir at 50 ° C for 1 hour, then add a modifier, the modifier is a 0.55 mol / L ethanol solution of hexadecyltrimethylammonium bromide, and the amount of the modifier added is 4% of the volume of the refined liquid. Continue stirring for 1.5 hours, filter through a plate and frame filter, and then dry to obtain modified magnesium hydroxide.

[0041] Comparative Examples 1 and 2 are provided below, in which modified magnesium hydroxide is prepared by changing the aging time after adding the modifier.

[0042] Comparative Example 1 The difference between Comparative Example 1 and Example 2 is that the aging is continued for 1 hour after stirring for 0.5 hours.

[0043] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that the aging is continued for 2 hours after stirring for 0.5 hours.

[0044] Table 1 Activation index and oil absorption value results of modified magnesium hydroxide prepared in Examples 1 to 5 and Comparative Examples 1 to 2

[0045] As can be seen from Table 1, the activation index of the modified magnesium hydroxide prepared by the preparation method of the present invention is relatively high, indicating that the modifier is almost completely coated on the surface of the magnesium hydroxide, making the magnesium hydroxide organic and lipophilic, which can ensure that the modified magnesium hydroxide is more evenly dispersed in the high molecular polymer, and the modification effect is good.

[0046] It can be seen from Examples 1 to 3 that as the amount of modifier added increases, the activation index shows a trend of first increasing and then decreasing. This is because when too little modifier is added, the alkyl structure generated by the modifier is insufficient, resulting in the magnesium hydroxide not being completely coated by the modifier molecular layer; when too much modifier is added, the modifier self-reacts, the bulk density increases, and the modifier does not wrap the magnesium hydroxide sufficiently. It can be seen from Examples 2, 4, and 5 that the longer the modification time, the smaller the activation index of the modified magnesium hydroxide, indicating that the stirring time is too long, which may cause the modifier coating layer of the modified magnesium hydroxide to fall off; it can be seen from Example 2 and Comparative Examples 1 and 2 that the aging time is conducive to the grafting of the modifier on the surface of the magnesium hydroxide, and the modification effect improves with the increase of the aging time.

[0047] The above one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: (1) The present invention uses salt production mother liquor as raw material, which has a wide source of raw materials and low production cost.

[0048] (2) The present invention uses nanofiltration membrane to filter the salt production mother liquor to obtain Mg-rich 2+ The refined liquid is used to prepare magnesium hydroxide with high purity, which can reach 99%. The high-purity magnesium hydroxide is then modified to obtain modified magnesium hydroxide with a high activation index.

[0049] (3) The activation index of the modified magnesium hydroxide prepared by the present invention is high, indicating that the modifier Grafted onto the surface of magnesium hydroxide with its long alkyl hydrophobic chains facing outward to prevent The electrostatic repulsion between the magnesium hydroxide and the modifier is eliminated. At the same time, the molecular layer formed by the modifier wraps the magnesium hydroxide almost completely. At this time, the dispersibility and compatibility of the modified magnesium hydroxide are greatly improved, and the mixing effect with high molecular polymers is better.

[0050] The present invention also provides a flame retardant material, using the modified magnesium hydroxide prepared by the method as described above, comprising: the flame retardant material is prepared from a set ratio of modified magnesium hydroxide, hexa(4-boric acid phenoxy)-cyclophosphazene and ethylene-vinyl acetate copolymer, the set ratio is (1-100): (1-100): 100, wherein the ratio of the sum of the proportions of modified magnesium hydroxide and hexa(4-boric acid phenoxy)-cyclophosphazene to the ethylene-vinyl acetate copolymer is 1:1; The modified magnesium hydroxide, hexa(4-boric acid phenoxy)-cyclophosphazene and ethylene-vinyl acetate copolymer are added into the torque rheometer according to a set ratio for mixing to obtain a mixed product, and the mixed product is vulcanized to obtain the flame retardant material.

[0051] Specific examples are provided below to prepare the flame retardant material.

[0052] Example 6 Modified magnesium hydroxide, hexa(4-boronic acid phenoxy)-cyclophosphazene and ethylene-vinyl acetate copolymer (EVA) were mixed in a torque rheometer at a ratio of 97:3:100 for 20 minutes to obtain a mixture, and the mixture was placed in a flat vulcanizer and melted and pressed at 150°C to obtain a flame retardant material.

[0053] Example 7 Modified magnesium hydroxide, hexa(4-boronic acid phenoxy)-cyclophosphazene and ethylene-vinyl acetate copolymer (EVA) were mixed in a torque rheometer at a ratio of 95:5:100 for 20 minutes to obtain a mixture, and the mixture was placed in a flat vulcanizer and melted and pressed at 150°C to obtain a flame retardant material.

[0054] Example 8 Modified magnesium hydroxide, hexa(4-boronic acid phenoxy)-cyclophosphazene and ethylene-vinyl acetate copolymer (EVA) were mixed in a torque rheometer at a ratio of 93:7:100 for 20 minutes to obtain a mixture, and the mixture was placed in a flat vulcanizer and melted and pressed at 150°C to obtain a flame retardant material.

[0055] Comparative Example 3 The difference between Comparative Example 3 and Example 6 is that modified magnesium hydroxide and hexa(4-boronic acid phenoxy)-cyclophosphazene are not added to the torque rheometer.

[0056] Comparative Example 4 The difference between Comparative Example 4 and Example 6 is that hexa(4-boronic acid phenoxy)-cyclophosphazene is not added to the torque rheometer.

[0057] Table 2 below shows the oxygen index results of the flame retardant materials prepared in Examples 6 to 8 and Comparative Examples 3 and 4.

[0058] Table 2

[0059] It can be seen from Table 2 that when modified magnesium hydroxide and hexa(4-boric acid phenoxy)-cyclophosphazene are not added as flame retardants, the LOI (oxygen index) value of the flame retardant material is only 18.6, which is flammable; when only modified magnesium hydroxide is used as a flame retardant, the LOI value of the flame retardant material is improved to 24.2%; when modified magnesium hydroxide is compounded with hexa(4-boric acid phenoxy)-cyclophosphazene, the LOI value of the flame retardant material increases, and the LOI value increases with the decrease of the ratio of magnesium hydroxide to hexa(4-boric acid phenoxy)-cyclophosphazene, indicating that the addition of hexa(4-boric acid phenoxy)-cyclophosphazene enhances the thermal stability of the flame retardant material, so the LOI value is improved.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flame retardant material, characterized in that: include: The flame retardant material is prepared from modified magnesium hydroxide, hexa(4-boric acid phenoxy)-cyclophosphazene and ethylene-vinyl acetate copolymer in a set ratio, wherein the set ratio is (1-100): (1-100): 100, wherein the ratio of the sum of the proportions of modified magnesium hydroxide and hexa(4-boric acid phenoxy)-cyclophosphazene to the ethylene-vinyl acetate copolymer is 1:1; The modified magnesium hydroxide, hexa(4-boric acid phenoxy)-cyclophosphazene and ethylene-vinyl acetate copolymer are added into the torque rheometer according to a set ratio for mixing to obtain a mixed product, and the mixed product is vulcanized to obtain the flame retardant material.

2. A method for preparing modified magnesium hydroxide using salt-making mother liquor, characterized in that: For preparing the modified magnesium hydroxide used as claimed in claim 1, comprising the following steps: The mother liquor of salt production is filtered by a nanofiltration membrane to obtain a refined liquid; Taking a first set amount of refined liquid and adding a second set amount of precipitant thereto, stirring at a set temperature for a first set time to obtain a mixed slurry; A third set amount of a modifier is added to the mixed slurry, wherein the modifier is an ethanol solution of hexadecyltrimethylammonium bromide, and the mixture is stirred at a set temperature for a second set time, and then filtered using a filter to obtain a solid product, and the solid product is dried to obtain modified magnesium hydroxide.

3. The method for preparing modified magnesium hydroxide using salt-making mother liquor according to claim 2, characterized in that: Before using nanofiltration membrane to filter the salt production mother liquor, the following steps are also included: The salt-making mother liquor is diluted 10 times by volume to obtain a diluted solution, and the diluted solution is filtered using a nanofiltration membrane to obtain a refined solution.

4. The method for preparing modified magnesium hydroxide using salt-making mother liquor according to claim 3, characterized in that: The precipitant is a sodium hydroxide aqueous solution, and the mass percentage concentration of the sodium hydroxide aqueous solution is 40%.

5. The method for preparing modified magnesium hydroxide using salt-making mother liquor according to claim 4, characterized in that: The first set amount is 100 mL, and the second set amount is 30 mL.

6. The method for preparing modified magnesium hydroxide using salt-making mother liquor according to claim 5, characterized in that: The concentration of the modifier is 0.55 mol / L, and the third set amount is 2%, 4%, and 6% of the first set amount.

7. The method for preparing modified magnesium hydroxide using salt-making mother liquor according to claim 2, characterized in that: The set temperature is 50°C.

8. The method for preparing modified magnesium hydroxide using salt-making mother liquor according to claim 2, characterized in that: The first set time is 1 hour.

9. The method for preparing modified magnesium hydroxide using salt-making mother liquor according to claim 2, characterized in that: The second setting time is 0.5h~1.5h.

10. The method for preparing modified magnesium hydroxide using salt-making mother liquor according to claim 2, characterized in that: The filter is a plate and frame filter.

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