High temperature yellowing resistant pyrophosphate piperazine salt complex and method of making same

Abstract

The present application relates to pyrophosphate piperazine salt flame retardant technical field, the present application discloses a kind of high-temperature yellowing-resistant pyrophosphate piperazine salt complex and preparation method thereof, comprising the following steps:1) pyrophosphate piperazine salt is carried out constant-temperature heat treatment, cooling to room temperature for standby;2) auxiliary one and auxiliary two are blended into composite agent according to 1:3~3:1 ratio;3) composite agent is diluted and blended with the pyrophosphate piperazine salt treated after step 1) according to 1:5~1:9, dry after standby, obtain premix agent;4) premix agent is added to the pyrophosphate piperazine salt treated after step 1) according to 0.5%~5% addition amount, blend, dry after 60~150 DEG C, obtain high-temperature yellowing-resistant low-temperature method pyrophosphate piperazine salt complex;The present application is low-temperature method pyrophosphate piperazine salt as object, through heat treatment and auxiliary addition, solve the yellowing problem of pyrophosphate piperazine salt itself, improve its application performance in plastics.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pyrophosphoric acid piperazine salt flame retardant, and particularly relates to a high-temperature yellowing-resistant pyrophosphoric acid piperazine salt compound and a preparation method thereof. BACKGROUND

[0002] Pyrophosphoric acid piperazine salt (PAPP) is an intumescent flame retardant integrating acid source, carbon source and gas source, has high carbonization efficiency, and can be used in the fields of polypropylene (PP), polyethylene (PE), ethylene-vinyl acetate copolymer (EVA), epoxy resin (EP) and the like. At present, PAPP is most widely used in the field of polypropylene. Compared with other intumescent flame retardants, PAPP has good heat resistance, hydrolysis resistance and excellent flame retardant performance. PAPP compound has a wide application in extruded plate processes and injection molding processes. With the increasing requirement of downstream users on the flame retardant performance of plastic products, the addition amount of PAPP compound is correspondingly increased. However, if the processing temperature is too low, the plastic is poorly plasticized, the flame retardant is not uniformly dispersed in the resin, and the plastic product has quality defects such as white spots and unstable flame retardant performance. If the processing temperature is too high, the plastic product will be yellow.

[0003] In order to solve the problem of yellowing of plastic products, the existing technology mainly focuses on the plastic itself, and the main means is to select pyrophosphoric acid piperazine salt with better whiteness or add anti-yellowing agents in the plastic product. However, it is not considered that the flame retardant pyrophosphoric acid piperazine salt itself will also yellow, so the technical means for solving the yellowing of plastic products has not been started from the preparation process of pyrophosphoric acid piperazine salt. At present, the preparation methods of polyphosphoric acid piperazine flame retardant mainly include: 1) metathesis method; 2) phosphorus pentoxide method; 3) ammonium dihydrogen phosphate method; 4) dipiperazine diphosphate condensation method. Most of the above preparation methods need to go through high temperature. The high-temperature process not only has high energy consumption but also needs to control the temperature well. If the temperature is slightly high, the carbonization of piperazine will be caused, which will affect the flame retardant efficiency. In addition, under high temperature, polyphosphoric acid piperazine is more likely to yellow, the whiteness is reduced, and the use performance is affected.

[0004] Therefore, the low-temperature method for preparing pyrophosphoric acid piperazine salt becomes a new trend. The pyrophosphoric acid piperazine salt prepared by this process has good whiteness, the production environment is friendly, the energy consumption is low, the equipment is easy to clean, and the operation is safe. Under high temperature, pyrophosphoric acid piperazine salt will also yellow. This may be due to the fact that the nitride or other impurities of pyrophosphoric acid piperazine salt are oxidized into chromophoric functional groups under high temperature. Piperazine and orthophosphoric acid piperazine exist in the volatile impurities, and these impurities will also be oxidized and yellow. In addition, under acidic conditions, the functional groups of pyrophosphoric acid piperazine salt subjected to high temperature are more likely to be oxidized into chromophoric groups. SUMMARY

[0005] This invention provides a high-temperature resistant piperazine pyrophosphate salt complex and its preparation method, solving the problem that polyphosphate piperazine is prone to yellowing in the prior art, which affects its performance.

[0006] The solution of the present invention is:

[0007] A method for preparing a high-temperature resistant, yellowing-resistant piperazine pyrophosphate salt complex includes the following steps:

[0008] 1) Perform constant temperature heat treatment on piperazine pyrophosphate and cool to room temperature for later use;

[0009] 2) Mix additive one and additive two in a ratio of 1:0.25 to 4 to form a composite agent;

[0010] 3) The composite agent is mixed with the piperazine pyrophosphate salt after heat treatment in step 1) at a mass ratio of 1:5 to 9, dried and set aside to obtain a premix;

[0011] 4) The premixed agent and the heat-treated piperazine pyrophosphate from step 1) are mixed at 60℃~150℃ and dried to obtain a high-temperature resistant, low-temperature piperazine pyrophosphate complex.

[0012] The first additive is alkaline hydrotalcite; the second additive is either polysiloxane or micro-sized silica.

[0013] As a preferred technical solution, in step 1), pyrophosphate and piperazine are mixed in an aqueous phase at room temperature to prepare the piperazine pyrophosphate salt; the temperature of the constant temperature heat treatment is 60-150℃, and the holding time is 0.5-4h.

[0014] As a preferred technical solution, in step 2), the stirring speed for mixing additive one and additive two is 500-2000 rad / min, and the time is 2-8 min.

[0015] As a preferred technical solution, in step 3), the stirring speed for mixing the composite agent with the heat-treated piperazine pyrophosphate salt in step 1) is 500-2000 rad / min, and the stirring time is 2-8 min.

[0016] As a preferred technical solution, in step 4), the mass ratio of the premix to the heat-treated piperazine pyrophosphate is 0.005 to 0.05:1, and the stirring speed for mixing the premix with the heat-treated piperazine pyrophosphate in step 1) is 500 to 2000 rad / min, and the stirring time is 2 to 8 min.

[0017] As a preferred technical solution, the alkaline hydrotalcite is one or more of calcium magnesium tin hydrotalcite, calcium magnesium aluminum hydrotalcite, and aluminum magnesium hydrotalcite.

[0018] Preferably, the micro-sized silicon dioxide has a particle size of 50-200 nm.

[0019] Preferably, the polysiloxane is a solid at room temperature and melts at a temperature of 60 DEG C or higher, and is selected from one or both of SILIMER 6150 and SILIMER 5500 from Chengdu Silikai Technology Co., Ltd.

[0020] The application also discloses a preparation method of the low-temperature pyrophosphoric acid piperazine salt complex with high-temperature yellowing resistance.

[0021] Advantages of the application:

[0022] 1. The low-temperature pyrophosphoric acid piperazine salt is used as the object, and the preparation process of the low-temperature pyrophosphoric acid piperazine salt does not undergo high-temperature treatment, so that the prepared pyrophosphoric acid piperazine salt contains volatile impurities, i.e., piperazine and piperazine orthophosphate; in the step of the application, the impurities, such as piperazine and piperazine orthophosphate, are removed through constant temperature heat treatment; and the existence of the impurities can cause high-temperature yellowing of the pyrophosphoric acid piperazine salt during use.

[0023] 2. The pyrophosphoric acid piperazine salt is more likely to yellow at high temperature, and the alkaline hydrotalcite can reduce the acidity of the pyrophosphoric acid piperazine salt, and through uniform blending, the alkaline hydrotalcite can be uniformly coated on the surface of the pyrophosphoric acid piperazine salt to form a protective layer, thereby playing a heat insulation role on the surface of the pyrophosphoric acid piperazine salt and further reducing yellowing of the pyrophosphoric acid piperazine salt at high temperature; the addition ratio of the alkaline hydrotalcite needs to be controlled, and the addition amount cannot be too much, otherwise, the protective effect cannot be achieved, and the stability and the flame-retardant property of the pyrophosphoric acid piperazine salt are affected.

[0024] 3. The polysiloxane in the second additive is a solid at room temperature, can be melted at the temperature in the step 4, and is uniformly stirred and attached to the surface of the pyrophosphoric acid piperazine after melting to form a protective layer, thereby playing a heat insulation role and reducing yellowing of the pyrophosphoric acid piperazine at high temperature; meanwhile, the flame-retardant property of the flame retardant is not affected; in addition, the polysiloxane can play a lubricating role after melting, thereby reducing temperature rise caused by friction and yellowing of the pyrophosphoric acid piperazine, and the polysiloxane after melting is beneficial to uniform dispersion of the first additive and further plays a role of the first additive.

[0025] 4. The micro-sized silicon dioxide in the second additive has strong dispersibility and high surface energy, so that the alkaline hydrotalcite has better dispersibility and certain wrapping performance on the pyrophosphoric acid piperazine, so that the first additive and the second additive can play a synergistic role, and the yellowing resistance of the pyrophosphoric acid piperazine salt is improved.

[0026] 5、The application uses the polysiloxane in solid state at room temperature, and the adding is convenient and easy to disperse, and no additional liquid additive loss weight scale and other equipment are needed, and the premixing agent is prepared first, the premixing agent is blended with the pyrophosphoric acid piperazine again, the dispersion of the solid state additive one and the additive two is more uniform, and the premixing agent is more fully wrapped with the pyrophosphoric acid; the hydrotalcite used in the application is basic hydrotalcite, and the addition of the hydrotalcite under the condition of no water will not affect the stability of the pyrophosphoric acid piperazine, and the existence of the alkali metal can reduce the acidity and prevent or slow down the oxidation into the chromophoric group. DETAILED DESCRIPTION

[0027] In order to make the technical means, creative features, purposes and effects realized by the application easy to understand, the application is further described below in combination with specific embodiments.

[0028] Embodiment one:

[0029] A high-temperature yellowing-resistant pyrophosphoric acid piperazine salt compound and a preparation method thereof, comprising the following steps:

[0030] 1) The pyrophosphoric acid and the piperazine are mixed in water phase at room temperature to prepare the pyrophosphoric acid piperazine salt, the pyrophosphoric acid piperazine salt is subjected to constant temperature heat treatment, and is cooled to room temperature for standby;

[0031] 2) The additive one and the additive two are blended into a composite agent according to the ratio of 1:3-3:1;

[0032] 3) The composite agent and the pyrophosphoric acid piperazine salt treated in step 1) are diluted and blended according to the ratio of 1:9, dried for standby, and a premixing agent is obtained;

[0033] 4) The premixing agent is added into the pyrophosphoric acid piperazine salt treated in step 1) according to the adding amount of 0.5%-5%, and is blended and dried at 60-150 DEG C to obtain a high-temperature yellowing-resistant low-temperature pyrophosphoric acid piperazine salt compound;

[0034] The additive one is basic hydrotalcite; and the additive two is polysiloxane or micro-sized silicon dioxide in solid state at room temperature;

[0035] The temperature of the constant temperature heat treatment is 60-150 DEG C, and the heat preservation time is 0.5-4 h;

[0036] In step 2), the stirring speed of the blending of the additive one and the additive two is 500-2000 rad / min, and the time is 2-8 min;

[0037] The stirring speed of the blending of the composite agent and the pyrophosphoric acid piperazine salt treated in step 1) is 500-2000 rad / min, and the stirring time is 2-8 min;

[0038] The stirring speed of the premixing agent and the pyrophosphoric acid piperazine salt treated by step 1) is 500-2000 rad / min, and the stirring time is 2-8 min.

[0039] The auxiliary agent is selected from one or more of calcium-magnesium-tin hydrotalcite, calcium-magnesium-aluminum hydrotalcite, and aluminum-magnesium hydrotalcite;

[0040] The particle size of the micro-sized silicon dioxide is 50-200 nm.

[0041] The polysiloxane is a solid at room temperature and melts above 60°C, and is selected from one or both of SILIMER 6150 and SILIMER 5500 from Chengdu Silikai Technology Co., Ltd.

[0042] The pyrophosphoric acid piperazine salt (i.e., PAPP complex) prepared by the above method is mixed according to the following formula requirements, then high-speed blending (200-2000 rad / min), extrusion (processing temperature 190-230°C), granulation, injection molding, constant temperature and humidity treatment are performed to obtain the flame-retardant polypropylene.

[0043] The flame-retardant polypropylene formula is composed of the following mass fractions:

[0044]

[0045] The mass ratio of each component in the compounded antioxidant is: main antioxidant 3114: auxiliary antioxidant 168 = 1:1.

[0046] Example Two

[0047] Different pyrophosphoric acid piperazine salts are prepared according to Table 1 below, and flame-retardant polypropylenes are prepared according to the formula and method of Example 1, and their properties are tested, with the results shown in Table 2.

[0048] Table 1:

[0049]

[0050]

[0051] Note: 1) S13, S14, S15, S16, S17 premixing agent contains 90% PAPP pure product + 10% complexing agent;

[0052] 2) The complexing agent in S13, S14, S15, S16, S17 premixing agent is prepared according to a 1:1 ratio of auxiliary agent one and auxiliary agent two.

[0053] Table 2 test results

[0054]

[0055]

[0056] Note: The treated PAPP compound agent contains 15% PAPP compound, 7.5% MPP, 2% zinc oxide, and 0.5% compound antioxidant.

[0057] As can be seen from Table 2, the present application has obvious improvement on the high-temperature yellowing resistance of PAPP after heat treatment of PAPP single product, and the high-temperature yellowing resistance is optimal after 110°C heat treatment. The high-temperature yellowing resistance of PAPP single product can be improved by using CaMgAl-DHT, MgAl-DHT, CaMgSn-DHT or nano-SiO2, 6150, 5500 alone, but the processing performance (serious reduction of melt index) and flame retardant performance of PAPP will be affected to some extent. The aluminum magnesium hydrotalcite has more obvious effect on the improvement of high-temperature yellowing resistance. Polysiloxane 6150 and polysiloxane 5500 obviously improve the processing performance (obvious improvement of melt index) of PAPP, and have no obvious effect on the flame retardant performance. The polysiloxane 5500 has optimal high-temperature yellowing resistance. The high-temperature yellowing resistance of PAPP pure product is improved to different degrees after compounding and premixing of CaMgAl-DHT, MgAl-DHT, nano-SiO2, 6150 and 5500. The flame retardant performance, processing performance and high-temperature yellowing resistance of PAPP blended with the premixing agent (MgAl-DHT: nano-SiO2 = 1:1, and then diluted 10 times with PAPP) are optimal. The reason is that MgAl-DHT is an alkaline substance, and PAPP has higher color stability after some reactions with pyrazophosphoric acid. In addition, nano-SiO2 has strong dispersibility and high surface energy, so that MgAl-DHT has better dispersibility and certain wrapping performance for PAPP, and therefore MgAl-DHT and nano-SiO2 have synergistic effect on the yellowing resistance of PAPP.

[0058] As can be seen from Table 2, if no heat treatment is performed, even if the additives one and two are added, the high-temperature yellowing resistance of PAPP cannot be obviously improved, which shows that the constant temperature heat treatment step of the present application has influence on the effect of the additives one and two. After heat treatment, some volatile impurities are removed, and without adding the additives one and two, the high-temperature yellowing resistance of PAPP cannot be greatly improved, which proves that the reason for the yellowing of pyrazophosphoric acid at low temperature is not only the volatile impurities contained in pyrazophosphoric acid, but also the oxidation of pyrazophosphoric acid itself to produce chromophoric functional groups under high temperature and acid conditions.

[0059] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high temperature yellowing resistant pyrophosphoric acid piperazine salt complex, characterized by, The method comprises the following steps: 1) pyrophosphoric acid and piperazine are mixed in water phase at room temperature to obtain the pyrophosphoric acid piperazine salt, which is then subjected to constant temperature heat treatment and cooled to room temperature for standby; 2) the auxiliary agent 1 and the auxiliary agent 2 are blended in a ratio of 1:3-3:1 to obtain a composite agent; 3) the composite agent and the pyrophosphoric acid piperazine salt after the heat treatment in step 1) are blended in a mass ratio of 1:5-9, dried, and then standby to obtain a premixing agent; 4) the premixing agent and the pyrophosphoric acid piperazine salt after the heat treatment in step 1) are blended and dried at 60-150 DEG C to obtain the high-temperature yellowing-resistant low-temperature pyrophosphoric acid piperazine salt composite. The auxiliary agent 1 is basic hydrotalcite; the auxiliary agent 2 is one of polysiloxane or micro-sized silicon dioxide; the micro-sized silicon dioxide has a particle size of 50-200 nm; the polysiloxane is a solid at room temperature and melts at a temperature of 60 DEG C or above, and can be melted at the temperature in step 4).

2. The process for preparing a high temperature, heat and light stabilized pyrophosphoryl piperazine salt complex according to claim 1, characterized in that: The pyrophosphoric acid and piperazine are mixed in water phase at room temperature to obtain the pyrophosphoric acid piperazine salt; the constant temperature heat treatment is performed at a temperature of 60-150 DEG C for 0.5-4 h.

3. The process for preparing a high temperature, heat and light stabilized pyrophosphoryl piperazine salt complex according to claim 1, wherein: The auxiliary agent 1 and the auxiliary agent 2 are blended at a stirring speed of 500-2000 rad / min for 2-8 min in step 2).

4. The process for preparing a high temperature, heat and light stabilized pyrophosphoryl piperazine salt complex according to claim 1, wherein: The composite agent and the pyrophosphoric acid piperazine salt after the heat treatment in step 1) are blended at a stirring speed of 500-2000 rad / min for 2-8 min in step 3).

5. The method for preparing a high-temperature yellowing-resistant piperazine pyrophosphate salt complex as described in claim 1, characterized in that: The mass ratio of the premixing agent to the pyrophosphoric acid piperazine salt after the heat treatment in step 1) is 0.005-0.05:1 in step 4); the premixing agent and the pyrophosphoric acid piperazine salt after the heat treatment in step 1) are blended at a stirring speed of 500-2000 rad / min for 2-8 min in step 4).

6. The process for preparing a high temperature, heat and light stabilized pyrophosphoryl piperazine salt complex according to claim 1, wherein: The basic hydrotalcite is one or more of calcium-magnesium-tin hydrotalcite, calcium-magnesium-aluminum hydrotalcite, and aluminum-magnesium hydrotalcite.

7. A high-temperature yellowing-resistant low-temperature pyrophosphoric acid piperazine salt composite prepared by the method in any one of claims 1-6.

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