CN113072745B - Preparation method and device of halogen-free composite flame retardant based on modified LDHs - Google Patents

Preparation method and device of halogen-free composite flame retardant based on modified LDHs Download PDF

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CN113072745B
CN113072745B CN202110298805.9A CN202110298805A CN113072745B CN 113072745 B CN113072745 B CN 113072745B CN 202110298805 A CN202110298805 A CN 202110298805A CN 113072745 B CN113072745 B CN 113072745B
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flame retardant
ldhs
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CN113072745A (en
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杨保俊
朱启文
王百年
张告时
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Hefei University of Technology
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K9/00—Use of pretreated ingredients
    • C08K9/04—Ingredients treated with organic substances
    • C08K9/06—Ingredients treated with organic substances with silicon-containing compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
    • B01F27/60—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a horizontal or inclined axis
    • B01F27/70—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a horizontal or inclined axis with paddles, blades or arms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F35/00—Accessories for mixers; Auxiliary operations or auxiliary devices; Parts or details of general application
    • B01F35/71—Feed mechanisms
    • B01F35/716—Feed mechanisms characterised by the relative arrangement of the containers for feeding or mixing the components
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/20—Oxides; Hydroxides
    • C08K3/22—Oxides; Hydroxides of metals
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/20—Oxides; Hydroxides
    • C08K3/22—Oxides; Hydroxides of metals
    • C08K3/2279—Oxides; Hydroxides of metals of antimony
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K7/00—Use of ingredients characterised by shape
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2201/00—Properties
    • C08L2201/02—Flame or fire retardant/resistant

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Abstract

The invention discloses a preparation method of a halogen-free composite flame retardant based on modified LDHs, which comprises the steps of adding divalent metal ions and trivalent metal ions into silane hydrolysate, slowly adding an alkali solution under the stirring condition, and drying after standing, crystallizing, filtering and washing the mixture to be neutral in sequence to obtain in-situ synthesized modified LDHs; in-situ synthesis of modified LDHs and antimony oxide Sb 2 O 3 Mixing with absolute ethyl alcohol, ball milling to obtain in-situ synthesized modified LDHs-Sb 2 O 3 Compounding fire retardant; in-situ synthesis of modified LDHs-Sb 2 O 3 And adding the composite flame retardant and the polypropylene PP material into a double-roll open mill, melting and blending, and then carrying out hot press molding by using a flat vulcanizing machine. The in-situ synthesized modified LDHs has lower oil absorption value and good dispersibility, can effectively improve the compatibility of the LDHs in a PP polymer matrix, endows a PP material with good flame retardant property, maintains good mechanical property, and has important practical application value.

Description

Preparation method and device of halogen-free composite flame retardant based on modified LDHs
Technical Field
The invention relates to the technical field of load flame retardants, in particular to a preparation method and a device of a modified LDHs-based halogen-free composite flame retardant.
Background
The traditional high polymer flame retardant is represented by a halogen-antimony flame retardant, halogen has high flame retardant efficiency, and the halogen-antimony forms a synergistic system, so that the flame retardant effect is more obvious. However, the PP material does not contain halogen, so that the addition amount of the halogen-antimony flame retardant is relatively large, the price of the halogen-antimony flame retardant is relatively high, and the cost is relatively high; meanwhile, the halogen antimony flame retardant can generate secondary pollution in the combustion process.
Layered double hydroxides (also called LDHs) are currently attracting much attention in the field of flame retardancy of high polymers due to their good thermal stability, halogen-free, non-toxic, smoke-suppressing and droplet-suppressing properties. However, as an inorganic flame retardant, the existing LDHs also have two obvious disadvantages as a composite flame retardant:
(1) Because the LDHs has small particle size and high surface energy, the LDHs particles are easy to agglomerate and are difficult to uniformly disperse in a plastic matrix of the composite material according to the Gibbs inertia principle;
(2) As the surface of the LDHs plate layer contains a large amount of-OH, the LDHs plate layer has stronger polarity and hydrophilic and oleophobic properties, so that the LDHs plate layer has poorer compatibility with a nonpolar PP polymer matrix, thereby causing the composite material to generate interface defects and leading the mechanical property of the composite material to be reduced.
In conclusion, the existing composite flame retardant material brings higher mechanical property loss while improving the flame retardant efficiency of the composite material, and becomes one of the research hotspots of the current additive type high polymer flame retardant or composite flame retardant.
Disclosure of Invention
The invention aims to provide a preparation method and a device of a halogen-free composite flame retardant based on modified LDHs, which are used for solving the technical problems that the existing composite flame retardant has poor flame retardant property and low compatibility with a high polymer matrix, and the flame retardant efficiency of a composite material is difficult to improve, and the loss of mechanical property is reduced as much as possible.
In order to solve the technical problems, the invention specifically provides the following technical scheme:
a preparation method of a halogen-free composite flame retardant based on modified LDHs comprises the following steps:
s100, adding divalent metal ions and trivalent metal ions into silane hydrolysate, slowly adding an alkali solution under the stirring condition, and drying after standing, crystallizing, filtering and washing the mixture to be neutral to obtain in-situ synthesized modified LDHs;
s200, synthesizing in situ modified LDHs and antimony oxide Sb 2 O 3 Mixing with absolute ethyl alcohol and ball milling to obtain in-situ synthesized modified LDHs-Sb 2 O 3 Compounding fire retardant;
s300, in-situ synthesis of modified LDHs-Sb 2 O 3 Adding the composite flame retardant and the polypropylene PP material into a double-roller open mill for meltingAnd hot-press molding by a flat vulcanizing machine after melting and blending.
As a preferable mode of the present invention, in step S100, the divalent metal ion includes Mg 2+ 、Ca 2+ 、Sr 2 + 、Ba 2+ 、Fe 2+ 、Zn 2+ 、Cu 2+ 、Ti 2+ 、Sn 2+ 、Cr 2+ 、Ni 2+ Either one or both of them;
the trivalent metal ion comprises Al 3+ 、Fe 3+ 、Co 3+ 、Mn 3+ 、V 3+ 、Ti 3+ 、Cr 3+ 、Bi 3+ 、Ce 3+ 、Pr 3+ 、W 3+ Either one or both.
As a preferable scheme of the invention, the silane hydrolysate comprises any one or two of chloropropyl trimethoxy silane CPTMO, gamma-aminopropyl triethoxy silane KH550, gamma-glycidyl ether oxygen propyl trimethoxy silane KH560 and gamma-methacryloxy propyl trimethoxy silane KH 570;
the alkali solution comprises one or two of sodium hydroxide, sodium carbonate and ammonia water, and the concentration of the alkali solution is 1-3 mol.L -1 。
In a preferred embodiment of the present invention, in step S100, the reaction temperature in the silane hydrolysate is 20 to 100 ℃, the stirring speed is 300 to 800rpm, the pH is controlled to 8 to 11, and the washing medium used in the washing step includes deionized water.
As a preferable embodiment of the present invention, in the step S200, the in-situ synthesized modified LDHs is 4 to 20 parts by weight, and Sb is 2 O 3 1 to 10 portions of absolute ethyl alcohol and 5 to 10 portions of absolute ethyl alcohol.
In a preferred embodiment of the present invention, in the step S200, the ball-to-material ratio of the ball-milling step is 1:1 to 5:1, and the ball-milling time is 4 to 12 hours.
In a preferred embodiment of the present invention, in the step S300, the temperature of the melt blending process is 165 to 185 ℃, and the rotation speed of the two-roll mill is 40 to 80rpm.
As a preferable aspect of the present invention, in step S300, the method for hot press forming by a flat press vulcanizer comprises:
preheating for 6-10 min at 165-185 ℃;
hot pressing for 5-20 min under 10 MPa;
cold pressing for 6-20 min under 10MPa to form.
The invention provides a preparation device of a preparation method of a halogen-free composite flame retardant based on modified LDHs, which comprises a mixing cavity body provided with a plurality of feeding pipes, wherein a hydrolysis mixing cavity and a forming cavity are arranged in the mixing cavity body, and a combined forming device is arranged in the forming cavity;
the combined forming device comprises a fixed rotating shaft axially arranged in the forming cavity, a steel mesh cavity disc is connected to the shaft body of the fixed rotating shaft through an axle sleeve equidistant key, a limiting groove matched with the steel mesh cavity disc is formed in the inner wall of the forming cavity, the end part of the mixing cavity far away from the hydrolysis mixing cavity is provided with a driving device used for driving the fixed rotating shaft to move axially along the mixing cavity, an opening and closing valve assembly is arranged on the shaft body of the hydrolysis mixing cavity and used for driving the fixed rotating shaft to move axially towards the forming cavity, the hydrolysis mixing cavity is closed, and the fixed rotating shaft is movably sleeved with the rotating shaft of the stirring device.
As a preferable scheme of the present invention, the fixed rotating shaft extends out of the mixing cavity, a friction basin sleeve is sleeved on a shaft body located between the mixing cavity and the driving device, and an electrode lead electrically connected to the steel mesh cavity disc through the fixed rotating shaft is arranged on an inner surface of the friction basin sleeve contacting with the mixing cavity.
Compared with the prior art, the invention has the following beneficial effects:
the invention adopts an in-situ synthesis modification method which completes the synthesis of LDHs and the modification of silane hydrolysate in one step, thereby achieving the effects of shortening the flow and simplifying the operation; the prepared in-situ synthesized modified LDHs has lower oil absorption value and good dispersibility, and can effectively improve the compatibility of the LDHs in a PP polymer matrix; prepared LDHs-Sb 2 O 3 The composite flame retardant endows the PP material with good flame retardant performance, maintains good mechanical performance and has important practical application value.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other embodiments can be derived from the drawings provided by those of ordinary skill in the art without inventive effort.
FIG. 1 is a schematic diagram of a preparation process of an in-situ synthesis modified LDHs type halogen-free composite flame retardant for PP according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a device for in-situ synthesis of modified LDHs according to an embodiment of the present invention;
the labels in the figure are:
1-a mixing chamber; 2-a feed pipe; 3-a hydrolysis mixing chamber; 4-forming a cavity; 5-combining a forming device; 6-a stirring device; 7-a pumping device; 8-an access pipe; 9-a discharge pipe; 10-a drive device; 11-an on-off valve assembly; 12-friction basin cover; 13-electrode lead;
501-fixing a rotating shaft; 502-a shaft sleeve; 503-steel mesh cavity plate; 504-a limiting groove;
1101-a first mesh disc; 1102-a second mesh disc; 1103-columnar protrusions.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in figure 1, the invention provides a preparation method of a modified LDHs-based halogen-free composite flame retardant, which comprises the following steps:
step S100, adding divalent metal ions and trivalent metal ions into silane hydrolysate, slowly adding an alkali solution under the stirring condition, and drying after standing crystallization, filtration and washing procedures are sequentially carried out until the solution is neutral to obtain in-situ synthesized modified LDHs;
step S200, in-situ synthesis of modified LDHs and antimony oxide Sb 2 O 3 Mixing with absolute ethyl alcohol, ball milling to obtain in-situ synthesized modified LDHs-Sb 2 O 3 Compounding fire retardant;
step S300, synthesizing the in-situ modified LDHs-Sb 2 O 3 And adding the composite flame retardant and the polypropylene PP material into a double-roll open mill, melting and blending, and then carrying out hot press molding by using a flat vulcanizing machine.
In step S100, the divalent metal ion includes Mg 2+ 、Ca 2+ 、Sr 2+ 、Ba 2+ 、Fe 2+ 、Zn 2+ 、Cu 2+ 、Ti 2+ 、Sn 2+ 、Cr 2+ 、Ni 2+ Either one or both of;
the trivalent metal ion comprises Al 3+ 、Fe 3+ 、Co 3+ 、Mn 3+ 、V 3+ 、Ti 3+ 、Cr 3+ 、Bi 3+ 、Ce 3+ 、Pr 3+ 、W 3+ Either one or both.
The silane hydrolysate comprises one or two of CPTMO, KH550, KH560 and KH 570;
the alkali solution comprises 1 to 3 mol.L -1 And any one or two of sodium hydroxide, sodium carbonate and ammonia water.
In step S100, the reaction temperature in the silane hydrolysate is 20-100 ℃, the stirring speed is 300-800 rpm, and the pH is controlled to be 8-11.
In the step S200, the in-situ synthesis modified LDHs is 4 to 20 parts by weight, and Sb is 2 O 3 1 to 10 portions of absolute ethyl alcohol and 5 to 10 portions of absolute ethyl alcohol.
In the step S200, the ball-material ratio of the ball-milling process is 1:1-5:1, and the ball-milling time is 4-12 h.
In the step S300, the temperature in the melt blending process is 165-185 ℃, and the rotation speed of the double-roll open mill is 40-80 rpm.
In the step S300, the hot press molding method of the plate vulcanizing machine includes:
preheating for 6-10 min at 165-185 ℃;
hot pressing for 5-20 min under 10 MPa;
cold pressing for 6-20 min under 10MPa to form.
The washing medium used in the washing process comprises deionized water.
Example 1
(1) Under the conditions that the water bath is kept at the constant temperature of 75 ℃ and the stirring speed is 500rpm, 37.51g of aluminum nitrate and 76.92g of magnesium nitrate are dissolved in 400mL of 25% ethanol solution, 2.5% of silane is added, 1 mol/L-1 sodium hydroxide solution is added dropwise at the speed of 1 drop per second until the pH value of the system is 10, the dynamic crystallization is continuously stirred for 1 hour, the mixture is aged for 24 hours, filtered and washed, the obtained filter cake is dried for 12 hours at the temperature of 75 ℃, and the in-situ synthesis modified LDHs is prepared by grinding.
(2) Weighing 15 parts of in-situ synthesis modified LDHs prepared in the step (1), 5 parts of Sb2O3, 10 parts of absolute ethyl alcohol and 70 parts of grinding balls, putting the materials into a ball milling tank, carrying out ball milling at the rotating speed of 500rpm for 8 hours, and then drying at 100 ℃ to obtain the in-situ synthesis modified LDHs-Sb 2 O 3 A composite flame retardant.
(3) 3 parts of in-situ synthesis modified LDHs-Sb prepared in the step (2) 2 O 3 Mixing the composite flame retardant and 7 parts of PP in a high-speed mixer, adding the mixture into a double-roll open mill, carrying out melt blending, and then carrying out hot press molding by using a flat vulcanizing machine to obtain the in-situ synthesis modified PPSex LDHs-Sb 2 O 3 -PP composite bars.
Example 2
(1) Under the conditions that the water bath is at a constant temperature of 75 ℃ and the stirring speed is 500rpm, 37.51g of aluminum nitrate and 76.92g of magnesium nitrate are dissolved in 400mL of 25% ethanol solution, 2.5% silane is added, 1 mol/L-1 sodium hydroxide solution is added dropwise at the speed of 1 drop per second until the pH value of the system is 10, the dynamic crystallization is continuously stirred for 1 hour, the mixture is aged for 24 hours, filtered and washed, the obtained filter cake is dried for 12 hours at the temperature of 75 ℃, and the in-situ synthesis modified LDHs is prepared by grinding.
(2) Weighing 16 parts of in-situ synthesis modified LDHs prepared in the step (1) and 4 parts of Sb 2 O 3 10 parts of absolute ethyl alcohol and 70 parts of grinding balls are put into a ball milling tank, ball milling is carried out for 8 hours at the rotating speed of 500rpm, and then drying is carried out at 100 ℃ to obtain the in-situ synthesized modified LDHs-Sb 2 O 3 A composite flame retardant.
(3) 3 parts of in-situ synthesis modified LDHs-Sb prepared in the step (2) 2 O 3 Mixing the composite flame retardant and 7 parts of PP in a high-speed mixer, adding the mixture into a double-roller open mill, carrying out melt blending, and then carrying out hot press molding by using a flat vulcanizing machine to prepare the in-situ synthesized modified LDHs-Sb 2 O 3 -PP composite bars.
Example 3
(1) Under the conditions that the water bath is kept at the constant temperature of 75 ℃ and the stirring speed is 500rpm, 37.51g of aluminum nitrate and 76.92g of magnesium nitrate are dissolved in 400mL of 25% ethanol solution, 2.5% of silane is added, 1 mol/L-1 sodium hydroxide solution is added dropwise at the speed of 1 drop per second until the pH value of the system is 10, the dynamic crystallization is continuously stirred for 1 hour, the mixture is aged for 24 hours, filtered and washed, the obtained filter cake is dried for 12 hours at the temperature of 75 ℃, and the in-situ synthesis modified LDHs is prepared by grinding.
(2) Weighing 17 parts of in-situ synthesis modified LDHs prepared in the step (1) and 3 parts of Sb 2 O 3 10 parts of absolute ethyl alcohol and 70 parts of grinding balls are put into a ball milling tank, ball milling is carried out for 8 hours at the rotating speed of 500rpm, and then drying is carried out at 100 ℃ to obtain the in-situ synthesized modified LDHs-Sb 2 O 3 A composite flame retardant.
(3) 3 parts of in-situ synthesis modified LDHs-Sb prepared in the step (2) 2 O 3 Mixing the composite flame retardant and 7 parts of PP in a high-speed mixer, adding the mixture into a double-roller open mill, carrying out melt blending, and then carrying out hot press molding by using a flat vulcanizing machine to prepare the in-situ synthesized modified LDHs-Sb 2 O 3 -PP composite bars.
Example 4
(1) Under the conditions that the water bath is kept at the constant temperature of 75 ℃ and the stirring speed is 500rpm, 37.51g of aluminum nitrate and 76.92g of magnesium nitrate are dissolved in 400mL of 25% ethanol solution, 2.5% of silane is added, 1 mol/L-1 sodium hydroxide solution is added dropwise at the speed of 1 drop per second until the pH value of the system is 10, the dynamic crystallization is continuously stirred for 1 hour, the mixture is aged for 24 hours, filtered and washed, the obtained filter cake is dried for 12 hours at the temperature of 75 ℃, and the in-situ synthesis modified LDHs is prepared by grinding.
(2) Weighing 18 parts of in-situ synthesis modified LDHs prepared in the step (1) and 2 parts of Sb 2 O 3 10 parts of absolute ethyl alcohol and 70 parts of grinding balls are put into a ball milling tank, ball milling is carried out for 8 hours at the rotating speed of 500rpm, and then drying is carried out at 100 ℃ to obtain the in-situ synthesized modified LDHs-Sb 2 O 3 A composite flame retardant.
(3) 3 parts of in-situ synthesis modified LDHs-Sb prepared in the step (2) 2 O 3 Mixing the composite flame retardant and 7 parts of PP in a high-speed mixer, adding the mixture into a double-roller open mill, carrying out melt blending, and then carrying out hot press molding by using a flat vulcanizing machine to prepare the in-situ synthesized modified LDHs-Sb 2 O 3 -PP composite bars.
Comparative example 1
And (3) adding the PP master batch into a double-roll open mill, melting into a mass, and then carrying out hot press molding by using a flat vulcanizing machine to obtain the PP sample strip.
Comparative example 2
(1) Under the conditions that the water bath is kept at the constant temperature of 75 ℃ and the stirring speed is 500rpm, 37.51g of aluminum nitrate and 76.92g of magnesium nitrate are dissolved in 400mL of solution, 1mol of L-1 sodium hydroxide solution is added into the solution dropwise at the speed of 1 drop per second until the pH value of the system is 10, the dynamic crystallization is continuously stirred for 1h, the solution is aged for 24h, filtered and washed, the obtained filter cake is dried for 12h at the temperature of 75 ℃, and the unmodified LDHs is prepared by grinding.
(2) And (2) mixing 3 parts of the unmodified LDHs prepared in the step (1) and 7 parts of PP in a high-speed mixer, adding into a double-roll open mill, carrying out melt blending, and then carrying out hot press molding by using a flat vulcanizing machine to obtain an unmodified LDHs-PP composite material sample strip.
Comparative example 3
(1) Under the conditions that the water bath is kept at the constant temperature of 75 ℃ and the stirring speed is 500rpm, 37.51g of aluminum nitrate and 76.92g of magnesium nitrate are dissolved in 400mL of 25% ethanol solution, 2.5% of silane is added, 1 mol/L-1 sodium hydroxide solution is added dropwise at the speed of 1 drop per second until the pH value of the system is 10, the dynamic crystallization is continuously stirred for 1 hour, the mixture is aged for 24 hours, filtered and washed, the obtained filter cake is dried for 12 hours at the temperature of 75 ℃, and the in-situ synthesis modified LDHs is prepared by grinding.
(2) And (2) mixing 3 parts of the in-situ synthesized modified LDHs prepared in the step (1) and 7 parts of PP in a high-speed mixer, adding the mixture into a double-roll open mill, and carrying out hot press molding by a flat vulcanizing machine after melt blending to prepare the in-situ synthesized modified LDHs-PP composite material.
Example Effect analysis
The LDHs powder and the PP composite material prepared in the above examples and comparative examples are tested for oil absorption value, flame retardance and mechanical properties, and the results are analyzed in comparison as follows:
(1) Oil absorption number
The oil absorption value of the LDHs powder prepared in the examples 1-4 and the comparative examples 1-3 is tested by referring to the GB/T15344-2012 standard, and the result is shown as 1.
Table 1 oil absorption test data for LDHs powders
Classification of Example 1 Example 2 Example 3 Example 4 Comparative example 1 Comparative example 2 Comparative example 3
Oil absorption number 18.81 18.62 18.76 18.69 - 22.58 18.71
As shown in Table 1, by comparing the oil absorption value test data of examples 1 to 4 and comparative examples 1 to 3, the oil absorption values of the LDHs powder before and after modification are obviously reduced, and the in-situ synthesized LDHs powder synthesized by the invention has lower surface energy, is not easy to agglomerate, has better dispersibility and effectively improves the compatibility with a PP (polypropylene) base material compared with unmodified LDHs.
(2) Oxygen index
The oxygen indexes of the PP composite specimens obtained in examples 1 to 4 and comparative examples 1 to 3 were measured by an HC-2 type oxygen index meter, and the results are shown in Table 2.
TABLE 2 PP composite spline oxygen index test data
Classification of Example 1 Example 2 Example 3 Example 4 Comparative example 1 Comparative example 2 Comparative example 3
Oxygen index 28.6 27.7 27.4 26.8 17.8 20.5 23.5
As shown in Table 2, comparing the oxygen index test data of examples 1-4 and comparative examples 1-3 of the present invention, it can be seen that the in situ synthesis of modified LDHs-Sb is superior to pure PP and unmodified LDHs-PP composite materials 2 O 3 The oxygen index of the-PP composite material is obviously improved, the flame retardant property is better, and the flame retardant property of the-PP composite material is along with that of Sb 2 O 3 The amount of addition increases.
(3) Grade of combustion
The PP composite material specimens obtained in examples 1 to 4 and comparative examples 1 to 3 were tested for vertical flame retardancy using a model CZF-3 vertical flame tester, and the results are shown in Table 2.
TABLE 3 UL-94 test results for PP composite bars
Classification Example 1 Example 2 Example 3 Example 4 Comparative example 1 Comparative example 2 Comparative example 3
Grade of combustion V-0 V-0 V-0 V-0 - - V-1
As shown in Table 3, when the UL-94 test results of examples 1 to 4 and comparative examples 1 to 3 of the present invention are compared, the in-situ synthesized modified LDHs-Sb of the present invention is compared with pure PP, unmodified LDHs-PP composite materials and in-situ synthesized modified LDHs-PP composite materials 2 O 3 The combustion grade of the-PP composite material reaches V-0 grade, and further proves that the in-situ synthesized modified LDHs-Sb is prepared by the method 2 O 3 The composite flame retardant has better flame retardant property.
(4) Flexural strength (MPa) and tensile strength (MPa)
The bending strength and tensile strength of the PP composite material specimens obtained in examples 1 to 4 and comparative examples 1 to 3 were measured by an AGX-V100KN type electronic universal tester, and the results are shown in Table 3.
TABLE 4 PP composite spline flexural Strength, tensile Strength test data
Classification Example 1 Example 2 Example 3 Example 4 Comparative example 1 Comparative example 2 Comparative example 3
Bending strength 36.84 37.01 37.52 38.07 40.93 35.43 37.86
Tensile strength 27.01 27.96 29.24 30.15 35.14 25.88 28.21
As shown in Table 4, when the flexural strength and tensile strength test data of examples 1 to 4 of the present invention and comparative examples 1 to 3 are compared, the in-situ synthesized modified LDHs-Sb of the present invention is compared with pure PP at the same addition amount 2 O 3 -a reduction in the mechanical properties of the PP composite; but compared with the unmodified LDHs-PP composite material, the in-situ synthesized modified LDHs-Sb prepared by the invention 2 O 3 The loss of mechanical properties of the PP composite is mitigated.
In conclusion, the in-situ synthesized modified LDHs powder developed by the invention has better compatibility with PP materials, and the in-situ synthesized modified LDHs-Sb 2 O 3 The composite flame retardant endows the PP composite material with good flame retardant performance, and simultaneously maintains good mechanical performance.
As shown in fig. 2, in order to further improve the compatibility of the surface of the modified LDHs powder with the PP material and the loss of mechanical properties during the modification:
the invention provides a preparation device of the preparation method of the in-situ synthesis modified LDHs type halogen-free composite flame retardant for PP, which comprises a mixing cavity 1 provided with a plurality of feeding pipes 2, wherein a hydrolysis mixing cavity 3 and a molding cavity 4 are arranged in the mixing cavity 1, a combined molding device 5 arranged in the molding cavity 4 is also arranged in the mixing cavity 1, a stirring device 6 is arranged in the hydrolysis mixing cavity 3, and part of the molding cavity 4 is made of high-temperature-resistant glass.
The mixing cavity 1 is provided with a pumping device 7 for conveying the solution between the hydrolysis mixing cavity 3 and the cavity where the combined forming device 5 is positioned, and the outer wall of the mixing cavity 1 opposite to the forming cavity 4 is provided with an access pipe 8 and a discharge pipe 9 along the axial direction of the mixing cavity 1 by taking the axis of the mixing cavity 1 as a symmetry axis.
The specific working process of the invention is as follows:
divalent metal ions, trivalent metal ions and silane hydrolysate are added into a hydrolysis mixing cavity 3 through a feed pipe 2, the hydrolysate in the hydrolysis mixing cavity 3 is sufficiently stirred through a stirring device 6, in the process, the alkali liquor is slowly added through the feed pipe 2, after the complete stirring is performed, stock solution treated by the alkali liquor in the hydrolysis mixing cavity 3 slowly enters a forming cavity 4 where a combined forming device 5 is located, when the stock solution in the hydrolysis mixing cavity 3 completely enters the forming cavity 4, the stock solution firstly entering the forming cavity 4 is in a standing state, the stock solution can also be conveyed into the hydrolysis mixing cavity 3 through modified LDHs which enters the forming cavity 4 in a crystallization state in the process of slowly entering the forming cavity 4 to promote the subsequent crystallization reaction process, a pumping device 7 extracts the solution on the surface layer of the forming cavity 4 and conveys the solution which is firstly entering the forming cavity 4 and tends to be completely crystallized to the hydrolysis mixing cavity 3, primary hydrolysis and alkali solution treatment is performed, the stock solution is sufficiently utilized, or waste liquid is discharged.
Until the stock solution is completely crystallized, the stock solution is attached to the combined forming device 5, and the crystallized substances attached to the combined forming device 5 are filtered, washed and dried through the access pipe 8 and the discharge pipe 9, so that the whole treatment process is operated in the same cavity.
Wherein, the combined forming device 5 can provide a filtering effect during the crystallization process, and the washing process can wash the crystallized substances on the combined forming device 5 by introducing deionized water into the access pipe 8 and the discharge pipe 9, and simultaneously, the introduction media of the access pipe 8 and the discharge pipe 9 are switched to be dry hot air for drying, and antimony oxide Sb in S200 can be introduced when the drying process is completed 2 O 3 Mixing with anhydrous ethanol, premixing before ball milling, and at the same timeThe stirring device 6 can drive the combined forming device 5 to rotate, so that pre-stirring grinding is carried out, and the ball milling time is reduced.
Because the modification completion amount can not be completely estimated in the metal ion and silane hydrolysis process and the alkali solution treatment modification process, only a target product can be obtained in a theoretical mode, raw materials can not be completely utilized, the existing S100 step operation is mostly carried out step by step, in the process, the oxygen content in the air and in the silane hydrolysis liquid can easily oxidize divalent metal ions, and the production amount is accurately controlled.
Further, the crystallization process is accelerated, and the integrated treatment process of drying after the filtration and washing process is carried out to neutrality is realized, the combined forming device 5 in the invention comprises a fixed rotating shaft 501 axially arranged in the forming cavity 4, the shaft body of the fixed rotating shaft 501 is connected with a steel mesh cavity disc 503 through a shaft sleeve 502 at equal intervals, wherein the steel mesh cavity disc 503 is a disc-shaped or annular hollow-out net-shaped structure, and the aperture of the steel mesh cavity disc 503 is slightly equal to or smaller than the average particle size of the crystallized substance.
Be provided with on the inner wall of shaping chamber 4 with steel mesh chamber dish 503 matched with spacing groove 504, the width of spacing groove 504 is greater than the thickness of steel mesh chamber dish 503, the tip of the mixing chamber 1 of keeping away from hydrolysis mixing chamber 3 is provided with the drive arrangement 10 that is used for driving fixed rotating shaft 501 along mixing chamber 1's axial displacement, fixed rotating shaft 501 is close to and installs the valve subassembly 11 that opens and shuts on the axle body of hydrolysis mixing chamber 3, the valve subassembly 11 that opens and shuts is used for when drive arrangement 10 drive fixed rotating shaft 501 carries out towards shaping chamber 4 direction axial displacement, closed hydrolysis mixing chamber 3 and shaping chamber 4, make steel mesh chamber dish 503 all reach extreme position department on the spacing groove 504 simultaneously, thereby make steel mesh chamber dish 503 on the fixed rotating shaft 501 close to each other, reduce the space in shaping chamber 4, compress into the die cavity 4, pressurize the solution in the shaping chamber 4 through the valve subassembly 11, and the pivot activity of fixed rotating shaft 501 and agitating unit 6 is cup jointed together.
Further, in order to form a controllable form of crystallized substance on the steel mesh cavity plate 503, a friction basin sleeve 12 is sleeved on a shaft body which extends out of the mixing cavity 1 from the fixed rotating shaft 501 and is located between the mixing cavity 1 and the driving device 10, an electrode wire 13 which is electrically connected with the steel mesh cavity plate 503 through the fixed rotating shaft is arranged on the inner surface of the friction basin sleeve 12, which is in contact with the mixing cavity 1, an electrostatic field is generated by friction between the friction basin sleeve 12 and the mixing cavity 1, and the electrostatic field is conducted through the electrode wire 13, so that a stable magnetic field environment is formed in the molding cavity 4.
The steel cavity plate 503 of the present invention is processed into a structure that does not have any chemical reaction with the modified LDHs.
The friction basin cover 12 is specifically a basin-shaped glass material structure.
Further, the stirring device of the present invention specifically includes a stirring shaft axially disposed in the mixing cavity 1, and a stirring blade disposed on the stirring shaft, wherein the stirring shaft and the fixed rotating shaft 501 are collinear, and are connected by a movable key.
The opening and closing valve assembly 11 comprises a first mesh disc 1101 and a second mesh disc 1102 which have the same diameter as the mixing cavity 1, wherein the first mesh disc 1101 is fixedly connected with the fixed rotating shaft 501, the second mesh disc 1102 is in movable key connection with the fixed rotating shaft 501, a limiting groove 504 of the second mesh disc 1102 is also arranged on the inner wall of the forming cavity 4, a columnar protrusion 1103 is arranged on the second mesh disc 1102, the columnar protrusion 1103 corresponds to the meshes of the first mesh disc 1101, when the driving device 10 drives the fixed rotating shaft 501 to move axially, the first mesh disc 1101 is in contact with the second mesh disc 1102, the columnar protrusion 1103 is matched with the meshes of the first mesh disc 1101, the forming cavity 4 and the hydrolysis mixing cavity 3 are closed, and vice versa, the opening is realized.
The pumping device is composed of the existing pump body and a conveying pipeline, and the driving device is any one of a hydraulic rod, a pneumatic rod or a screw-nut pair transmission assembly.
The above embodiments are only exemplary embodiments of the present application, and are not intended to limit the present application, and the protection scope of the present application is defined by the claims. Various modifications and equivalents may be made by those skilled in the art within the spirit and scope of the present application and such modifications and equivalents should also be considered to be within the scope of the present application.

Claims (9)

1. A preparation method of a modified LDHs-based halogen-free composite flame retardant is characterized by comprising the following steps:
s100, adding divalent metal ions and trivalent metal ions into silane hydrolysate, slowly adding an alkali solution under the stirring condition, and drying after standing, crystallizing, filtering and washing the mixture to be neutral to obtain in-situ synthesized modified LDHs;
s200, synthesizing in situ modified LDHs and antimony oxide Sb 2 O 3 Mixing with absolute ethyl alcohol, ball milling to obtain in-situ synthesized modified LDHs-Sb 2 O 3 Compounding a flame retardant;
s300, in-situ synthesis of modified LDHs-Sb 2 O 3 Adding the composite flame retardant and the polypropylene PP material into a double-roll open mill, melting and blending, and then carrying out hot press molding by using a flat vulcanizing machine;
the preparation device comprises a mixing cavity (1) provided with a plurality of feeding pipes (2), a hydrolysis mixing cavity (3) and a forming cavity (4) are arranged in the mixing cavity (1), a combined forming device (5) installed in the forming cavity (4) is arranged in the forming cavity (1), a stirring device (6) is arranged in the hydrolysis mixing cavity (3), a pumping device (7) used for conveying a solution between the cavities where the hydrolysis mixing cavity (3) and the combined forming device (5) are located is arranged on the mixing cavity (1), and an access pipe (8) and a discharge pipe (9) along the axial direction of the mixing cavity (1) are arranged on the outer wall of the mixing cavity (1) right opposite to the forming cavity (4) by taking the axis of the mixing cavity (1) as a symmetry axis;
the combined forming device (5) comprises a fixed rotating shaft (501) axially arranged in a forming cavity (4), a shaft body of the fixed rotating shaft (501) is connected with a steel mesh cavity disc (503) through a shaft sleeve (502) at equal intervals in a key mode, a limiting groove (504) matched with the steel mesh cavity disc (503) is formed in the inner wall of the forming cavity (4), the end portion, far away from the hydrolysis mixing cavity (3), of the mixing cavity (1) is provided with a driving device (10) used for driving the fixed rotating shaft (501) to move axially along the mixing cavity (1), the fixed rotating shaft (501) is close to the shaft body of the hydrolysis mixing cavity (3) and is provided with an opening and closing valve assembly (11), the opening and closing valve assembly (11) is used for driving the fixed rotating shaft (501) to move towards the forming cavity (4) in an axial direction, the hydrolysis mixing cavity (3) and the forming cavity (4) are closed, and the fixed rotating shaft (501) and a rotating shaft of the stirring device (6) are movably sleeved together.
2. The method as claimed in claim 1, wherein in step S100, the divalent metal ions comprise Mg 2+ 、Ca 2+ 、Sr 2+ 、Ba 2+ 、Fe 2+ 、Zn 2+ 、Cu 2+ 、Ti 2+ 、Sn 2+ 、Cr 2+ 、Ni 2+ Either one or both of;
the trivalent metal ion comprises Al 3+ 、Fe 3+ 、Co 3+ 、Mn 3+ 、V 3+ 、Ti 3+ 、Cr 3+ 、Bi 3+ 、Ce 3+ 、Pr 3+ 、W 3+ Either one or both.
3. The preparation method of the halogen-free composite flame retardant based on the modified LDHs as claimed in claim 1, wherein the silane hydrolysate comprises any one or two of chloropropyl trimethoxy silane CPTMO, gamma-aminopropyl triethoxy silane KH550, gamma-glycidoxypropyl trimethoxy silane KH560 and gamma-methacryloxypropyl trimethoxy silane KH 570;
the alkali solution comprises one or two of sodium hydroxide, sodium carbonate and ammonia water, and the concentration of the alkali solution is 1-3 mol.L -1 。
4. The method for preparing halogen-free composite flame retardant based on modified LDHs as claimed in claim 2, wherein in step S100, the reaction temperature in the silane hydrolysate is 20-100 ℃, the stirring speed is 300-800 rpm, the pH is controlled at 8-11, and the washing medium used in the washing process comprises deionized water.
5. The method for preparing halogen-free composite flame retardant based on modified LDHs as claimed in claim 1, wherein in step S200, the in situ synthesis of modified LDHs is carried out in an amount of 4-20 parts by weight, sb is added 2 O 3 1 to 10 portions of absolute ethyl alcohol and 5 to 10 portions of absolute ethyl alcohol.
6. The method as claimed in claim 1, wherein in step S200, the ball-to-material ratio of the ball-milling step is 1:1-5:1, and the ball-milling time is 4-12 h.
7. The method as claimed in claim 1, wherein the temperature of the melt blending process in step S300 is 165-185 ℃, and the rotation speed of the two-roll mill is 40-80 rpm.
8. The preparation method of the halogen-free composite flame retardant based on the modified LDHs as claimed in claim 1, which is characterized in that:
in the step S300, the hot press molding method of the plate vulcanizing machine includes:
preheating for 6-10 min at 165-185 ℃;
hot pressing for 5-20 min under 10 MPa;
cold pressing for 6-20 min under 10MPa to form.
9. The preparation method of the halogen-free composite flame retardant based on the modified LDHs as claimed in claim 1, wherein the fixed rotating shaft (501) extends out of the mixing cavity (1) and is positioned on a shaft body between the mixing cavity (1) and the driving device (10) and is sleeved with a friction basin sleeve (12), and an electrode wire (13) electrically connected with the steel mesh cavity disc (503) through the fixed rotating shaft is arranged on the inner surface of the friction basin sleeve (12) contacted with the mixing cavity (1).
CN202110298805.9A 2021-03-20 2021-03-20 Preparation method and device of halogen-free composite flame retardant based on modified LDHs Active CN113072745B (en)

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