JP2918127B2 - Method for producing fine particles of type II ammonium polyphosphate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing fine ammonium polyphosphate (hereinafter referred to as APP) having a type II crystal structure and a crystal surface having a particle diameter of 10 .mu.m or less and having a crystal surface of 80% by weight or more. More specifically, when the product of the present invention is internally added or impregnated to an olefin resin and a molded product or fiber, the mechanical properties of the olefin resin and the molded product or fiber are less reduced, and the particle size is reduced. The present invention relates to APP fine particles which provide bleed resistance and flame retardancy equivalent to conventional products despite an increase in specific surface area.

[0002]

2. Description of the Related Art It is well known that APP can be obtained by subjecting a mixture of a phosphate-containing substance and an ammonia-condensing agent to heat condensation. However, known APPs have the purpose of imparting flame-retardant performance to olefin resins and molded products,
Or when added or impregnated to fibers or the like: Uneven flame-retardant performance and reduced mechanical strength due to large particle size. 2. Bleed resistance is reduced due to the type I crystal structure. 3. Degradation of bleed resistance due to distortion of the APP crystal surface due to excessive mechanical pulverization. 4. APP 5%-Bleed resistance decreased due to insufficient viscosity of hot water suspension solution. And other inconvenient problems.

[0003]

[Problems to be solved by the invention] For example,
The particle diameter of APP according to the specification of Japanese Patent No. 11280 is 63 μm or less and 94% (average particle diameter 18 μm), and the crystal diameter is large. Is inconvenient. APP disclosed in JP-B-53-15478 and JP-B-49-30356 has an I-type crystal structure. The present inventors have previously provided in Japanese Patent Application No. 3-12900 a type II APP microparticle in which the above disadvantages have been solved and a method for producing the same. However, the crystallization method according to the production method is technically difficult and it is difficult to perform stable production. An object of the present invention is to provide a method for producing APP fine particles that solves these disadvantages.

[0004]

Means for Solving the Problems The present invention provides the following (1) to
It has the configuration of (4). (1) In a method for producing ammonium polyphosphate, an ammonia gas is supplied under a nitrogen gas atmosphere by reacting an approximately equal molar amount of ammonium phosphate and phosphoric anhydride at an elevated temperature in an ammonia gas atmosphere. A first-stage reaction step that is not performed and a second-stage reaction step in which 30 to 90% of a stoichiometric amount of ammonia gas (or a substance that generates ammonia gas when heated; hereinafter referred to as an ammonifying agent) is instantaneously supplied; And producing a fine particle of type II ammonium polyphosphate, wherein the crystallization is carried out through three stages of a third stage of a reaction step in which the stoichiometric amount of ammonia gas is more than the remaining amount of ammonia. Method. (2) In a first-stage reaction step in which ammonia is not supplied under a nitrogen gas atmosphere, a reaction temperature of 250 ° C. to 320 ° C.
2. The production method according to the above 1, wherein the temperature is maintained for 10 minutes or more. (3) The production method according to the above (1), wherein the supply time is from 5 minutes to 30 minutes in the second reaction step in which 90% or less of the stoichiometric amount of ammonia is instantaneously supplied. (4)
2. The production method according to the above item 1, wherein in the third reaction step in which ammonia is gradually added and aged, an atmosphere temperature of 240 ° C. or more is applied for 30 minutes or more. The configuration and effect of the present invention will be described in detail below. The APP fine particles of the present invention are particles having a particle diameter of 10 μm or less and 75% by weight or more that suppress the growth of crystals while maintaining the type II structure in the reaction process. As shown in FIG. 1, the crystal structures of type I and type II are No. 1 described in the JCPDS card, respectively. 22006
1, No. It has an X-ray diffraction pattern of 220062. When the APP fine particles of the present invention are manufactured by heating substantially equal molar amounts of ammonium phosphate and phosphoric anhydride (P ₂ O ₅ ) at an elevated temperature in a gaseous ammonia atmosphere, the type II structure is changed. It is obtained by a first-stage reaction step of forming, a second-stage reaction step of generating fine crystal nuclei with an ammoniating agent, and a third-stage reaction step of cooling after heat aging in an atmosphere of gaseous ammonia.
The first reaction step for forming the type II structure of the present invention includes:
A substantially equimolar amount of ammonium phosphate and phosphoric anhydride is mixed in a nitrogen gas atmosphere at 250 ° C. or higher, preferably 270 ° C. or higher.
Heat melting and stirring at a temperature of 20 ° C. or less. The molar ratio between ammonium phosphate and phosphoric anhydride is preferably substantially equal, and if the molar ratio is not equal, I-type APP is mixed.
At a reaction temperature of 250 ° C. or lower and before the first reaction step, type I and other types of APP are produced as by-products, and the viscosity of the 5% hot aqueous solution is abnormally reduced, which causes a problem.

[0005] The compound for supplying ammonia of the present invention (hereinafter referred to as "ammonifying agent") is a substance which generates ammonia gas by heating, such as gaseous ammonia, urea, ammonia carbonate, ammonia carbamate, or a mixture thereof, Aqueous solution. The second-stage reaction step of generating fine crystal nuclei with the ammoniating agent of the present invention is performed by stirring, kneading, or spraying the initial molten reaction solution obtained in the first reaction step in which the type II structure is formed. Is added in such an amount that an instantaneous supply of 30 to 90% of the stoichiometrically required amount of ammonia can be instantaneously performed, and instantaneous crystallization takes place. If the amount of the ammonifying agent is too large, type I and other types of APP are by-produced, and the viscosity of the 5% hot aqueous solution decreases.
On the other hand, if the amount is too small, APP larger than a desired particle diameter can be obtained. The third reaction step of the present invention refers to the step of reacting the granular powder obtained in the second reaction step at 250 ° C., preferably 270 ° C.
The stirring treatment is carried out at a temperature of not lower than 320 ° C and not higher than 320 ° C for 1 to 10 hours, preferably 2 to 5 hours.

Although the reaction is derived from a known reaction formula, the type II APP fine particles of the present invention proceed by the following two-stage reaction. First stage reaction step: Initial melting reaction (NH ₄ ) ₂ HPO ₄ + P ₂ O ₅ → 3 / n [(NH ₄ ) _2/3 H _1/3 PO ₃ ] _n or NH ₄ H ₂ PO ₄ + P _{2 O 5 → 3 / n [} (NH 4) 1/3 H 2/3 PO 3] n second reaction step: metaphase crystallization reaction _{3 / n [(NH 4)} 2/3 H 1/3 PO 3 ] _n + 1 / 2CO (NH ₃ ) ₂ + 1 / 2H ₂ O → 3 / n (NH ₄ PO ₃ ) _n or 3 / n [(NH ₄ ) _1/3 H _2/3 PO ₃ ] _n + CO (NH ₃ ) ₂ + H ₂ O → 3 / n (NH ₄ PO ₃ ) _n (n <10000)

[0007]

The APP of the present invention has a type II crystal structure, a smooth crystal surface, and a small particle size (10 μm or less, 80% by weight or more). It disperses finely when internally added. Therefore, the mechanical strength is improved. By the known method
Type II APP and commercially available type II APP (Exo
lit422) has a particle diameter of 63% or less, 94%, and an average particle diameter of 15 μm, which is much larger than the APP of the present invention. or,
This APP has a property that it cannot be made into fine particles by mechanical pulverization. In the case of fine particles obtained by excessively pulverizing, for example, pulverizing for several hours with a ball mill or the like, crystals are torn in the length direction or the crystal surface is damaged, lose smoothness and become strained.

The APP of the present invention has a type II crystal structure,
Further, since the surface of the crystal is smooth, it is internally added to an olefin resin and a molded article or fiber, and when exposed to a high-temperature and high-humidity atmosphere, the surface of the olefin resin and the molded article or fiber is internally added. No elution of APP is observed. A of the present invention
PP is a polymer having a molecular weight of about 3,000,000, and the hot water solution has high viscosity. For example, the viscosity of a 5% hot water solution is 100 to
Indicates 10,000 centipoise. Thus, the AP of the present invention
P fine particles can be suitably used as a flame retardant for resins, fibers, papermaking, paints, and the like. Examples will be described below.

[0009]

EXAMPLES The raw materials and physical properties used were evaluated as follows. Raw material: Ammonia phosphate: Industrial mono- and di-ammonium phosphate manufactured by Ohira Chemical Industry Co., Ltd. Phosphoric anhydride: Phosphoric anhydride (P ₂ O ₅ ) manufactured by Lhasa Kogyo Co., Ltd. Urea: manufactured by Ube Industries, Ltd. Granular urea Ammonium carbonate: First class reagent Commercially available type II APP: Exolit422 type I APP manufactured by Hoechst Co .: In-house synthesized polypropylene resin: ethylene-propylene block copolymer (ethylene content 8.5% by weight, melt flow rate 20 g / 10 minutes) ) Polyethylene resin: M680 (melt index 6.5 g / 10 min.) Manufactured by Chisso Corporation Ethylene-propylene rubber: manufactured by Nippon Synthetic Rubber Co., Ltd. (E
P 02P) Flame retardant aid: 2-piperazinylene-4-morpholino-1,
3,5-triazine polymer

Physical property measuring method 1) Particle size and particle size distribution A particle size distribution measuring device based on the equation of Stokes sedimentation. 2) 5 g of a 5% solution viscosity APP was suspended in 95 g of hot pure water at 80 ° C., the mixture was stirred and dissolved at the same temperature for 5 minutes, and a part cooled to 25 ° C. was replaced with Tokyo Keiki Co., Ltd. Co., Ltd. Viscometer [VISCONIC [E
MD]. 3) Molecular weight Measured with a high performance liquid chromatograph manufactured by Waters, using polyethylene glycol and polyethylene oxide of known molecular weight as reference substances. 4) Crystal form X-ray diffraction method 5) Flammability UL-94 (Underweriters Labor)
atories). In UL-94, a vertical combustion test was adopted, and the evaluation was based on V-2,
V-1 and V-0. Regarding the cotton ignition rate, it was confirmed whether or not the melt dropped on the surgical absorbent cotton placed 30 cm below the test piece to ignite the surgical absorbent cotton. 6) Bleed test A test piece (100 mm long) was placed in a thermo-hygrostat at 80 ° C and 80% RH.
After exposure for a certain period of time,
The sample was dried for 2 hours in a hot-air dryer at ℃ and left in a desiccator at room temperature for 24 hours. The surface electric resistance was measured in accordance with JIS K6911. Up to the bleed retention days. 7) Izod impact test (with notch) Based on JIS K7110. 8) DuPont drop weight impact test A 50 × 50 × 2 mm test piece was used according to JIS K-54.
Using the apparatus described in Section 00-8.3.2, using a barrel with a sample temperature of 10 ° C. and a radius of curvature of 1/4 inch at the tip, and a barrel load of 3/2 inch inside diameter, And the falling height was changed and evaluated.

EXAMPLE 1 (NH ₄ ) ₂ H was placed in a 5 kl tabletop kneader preheated to 290 to 300 ° C. while maintaining a nitrogen gas atmosphere.
PO ₄ 660 g (5 mol), was placed a mixture of P ₂ O ₅ 710g ₍₅ moles), heated and stirred. After 5 minutes, the entire amount melted to become a melt at 286 ° C. After maintaining the same temperature and stirring for 20 minutes, 97.5 g of a 76.9% (80 ° C.) urea solution (corresponding to 50% of the stoichiometrically required amount of by-product ammonia) was added in 7 minutes. Spray added. Continuously supply ammonia at 2 L / min for 2 hours 250
The mixture was stirred and aged at -270 ° C to obtain 1450 g of a powdery APP containing a small amount of aggregates. The aggregate was coarsely crushed with a crusher (AP-B type manufactured by Hosokawa Micron) in order to separate the aggregate into single crystals. Table 1 shows the physical properties of the obtained product.

Examples 2 to 6 and Comparative Examples 1 to 5 Except that the time for holding the melt at 286 ° C., the addition amount of the 76.9% urea solution, and the time required for the addition are shown in Table 1 below. Same as 1. Table 2 shows the physical properties of the obtained product.

[0013]

[Table 1]

[0014]

[Table 2]

Example-7, Comparative Example-6 As a polypropylene resin, an ethylene content of 8.5% by weight, a melt flow rate (temperature of 230 ° C, load of 2.16)
10 g of molten resin when Kg is added) 20 g
20% of various APPs obtained in Examples 1 to 6 and Comparative Examples 1 to 5 to 70% of a crystalline ethylene-propylene block copolymer of / 10 min, and 2-piperazinylene which is a compound (N) 10% by weight of 4-morpholino-1,3,5-triazine polymer 0.15% by weight of 2,6-di-t-butyl-p-cresol as a resin stabilizer Di-myristyl-β, β′-thiodipro 0.20% by weight of pionate and 0.10% by weight of calcium stearate were put into a cooking mixer (trade name) and mixed by stirring for 1 minute. The resulting mixture was melt-kneaded with Minimax (trade name) and extruded at a temperature of 210 ° C. into pellets. Each of the pellets thus obtained was pressed at a pressing temperature of 210
Predetermined test pieces for a bleed test were each molded using a hot press molding machine set at ° C. The bleed test was measured using the test piece. The results are shown in Table 3.

[0016]

[Table 3]

[Brief description of the drawings]

FIG. 1 shows X-ray diffraction patterns of Form I and Form II. >

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C01B 25/40

Claims (4)

(57) [Claims] 1. A method for producing ammonium polyphosphate by reacting approximately equal molar amounts of ammonium phosphate and phosphoric anhydride at an elevated temperature in an ammonia gas atmosphere. A first-stage reaction step in which supply is not performed and a second-stage reaction in which ammonia gas (or a substance that generates ammonia gas when heated; hereinafter referred to as an ammonifying agent) instantaneously supplies 30 to 90% of a stoichiometric amount. Crystallization is carried out through three steps of a third reaction step in which a stoichiometric amount of ammonia gas more than the remaining amount of ammonia is gradually added and ripened. Manufacturing method. 2. A reaction temperature of 250 ° C. in a first reaction step in which no ammonia is supplied under a nitrogen gas atmosphere.
The method according to claim 1, wherein the temperature is maintained at −320 ° C. for 10 minutes or more. 3. The production method according to claim 1, wherein in the second stage reaction step in which 90% or less of the stoichiometric amount of ammonia is instantaneously supplied, the supply time is 5 minutes to 30 minutes. 4. The method according to claim 1, wherein in the third reaction step for slowly adding and ripening the ammonia, the atmosphere temperature of 240.degree.
The production method according to claim 1, wherein the treatment is carried out for more than one minute.