JPH0516366B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to stabilized red phosphorus in which the surface of red phosphorus particles is coated with a deposited coating of a titanium-cobalt compound and an organic resin, and a method for producing the same. The stabilized red phosphorus according to the present invention is particularly useful as a retardant agent for synthetic resins, and can be used in the fields of resins, paints, and adhesives. [Prior Art] It is well known that red phosphorus imparts an excellent flame retardant effect to synthetic resins, and is actually used as a flame retardant. However, when red phosphorus is used as it is, it reacts with moisture and causes a hydrolysis reaction accompanied by the generation of phosphine gas. Many red phosphorus modifications have been proposed. For example, a method of depositing aluminum hydroxide on the surface of red phosphorus using aluminum sulfate and sodium hydrogen carbonate [Gmelin, Handbook der Anorganisien Chemier, 8th edition (1964)]
“Phosphorus” Part B, p. 83 (Gmelin. “Handbuch
8th Edition
(1964), vol Phosphorus, Parts B.Page 83)]
has been reported. However, this red phosphorus modification method requires coating a large amount of aluminum hydroxide in order to completely stabilize red phosphorus, which not only reduces its effectiveness as a flame retardant, but also reduces the effectiveness of red phosphorus depending on the application. It may have a negative effect. Another example of a red phosphorus reforming method is a method of coating aluminum hydroxide with a composite of zinc or magnesium hydroxide (U.S. Pat. No. 2,635,953).
specification), modified red phosphorus coated with a thermosetting resin (Japanese Patent Application Laid-Open No. 105996/1983), modified red phosphorus coated with a thermosetting resin after converting the red phosphorus surface into a metal phosphide (Japanese Patent Laid-Open No. 105996/1983) modified red phosphorus (US Pat. No. 4,421,782) in which the surface of red phosphorus is coated with a hydrated oxide of titanium; or modified red phosphorus in which the surface of red phosphorus is coated with a hydrated oxide of titanium. Modified red phosphorus coated with thermosetting resin
-141609) etc. have been proposed. [Problems to be Solved by the Invention] As mentioned above, many proposals have been made for stabilizing red phosphorus through modification, but all of them have advantages and disadvantages, and still have some important problems. In particular, red phosphorus is easily hydrolyzed in the presence of moisture and is accompanied by the generation of phosphine gas, which is odorous and toxic even in a very small amount, so it has been extremely difficult to completely suppress the generation of this gas. For this reason, proposals have been made to suppress the generated phosphine gas by coexisting metals that have a high affinity with phosphine gas, such as heavy metals such as copper and nickel. However, many heavy metals have the disadvantage of accelerating the hydrolysis of red phosphorus. This results in a decrease in moisture resistance and promotes the generation of phosphine gas. Furthermore, the modified red phosphorus disclosed in Japanese Patent Application Laid-open No. 52-125489 can be considered to be a type of plating film by the so-called galvanic method, but it is an extremely thin and incomplete metal phosphide film. The present invention has been achieved through extensive research and exploration of various stabilization methods in order to substantially completely suppress the generation of phosphine gas accompanying the decomposition of red phosphorus.
When red phosphorus particles were coated with a titanium-cobalt composite hydrated oxide and an organic resin film, the present invention was completed based on the discovery that surprisingly stable red phosphorus powder could be obtained. [Means for Solving the Problem] and [Operation] That is, the present invention provides a stabilizing method characterized by coating the surface of red phosphorus particles with a titanium-cobalt complex hydrated oxide and an organic resin. Fine particles of titanium-cobalt complex hydrated oxide are produced by adding an alkaline agent to an aqueous suspension of red phosphorus and a mixed salt of titanium salt and cobalt salt to neutralize it. The present invention relates to a method for producing stabilized red phosphorus, which comprises depositing a precipitate on the surface of red phosphorus particles and simultaneously or subsequently coating the surface with an organic resin. The present invention will be explained in detail below. The red phosphorus particles in the present invention are at least as large as
100 μm or less, preferably 44 μm or less, and the average particle size is 5 to 30 μm, preferably 10 to
A thickness in the range of 20 μm is preferred. Further, since fine powder increases the surface area of the particles and tends to become unstable, it is preferable to use particles with a particle size of about 1 μm or less that are cut as much as possible. Therefore, the red phosphorus particles in the present invention are
It is preferable that the particle size is substantially in the range of 1 to 100 μm, and even if particles with a particle size outside the above range are contained, the content of particles with a particle size of 1 μm or less and 100 μm or more is 5% by weight or less is desirable. Note that the particle size and average particle size are values measured by a sieving method or a Coulter counter method. The stabilized red phosphorus according to the present invention is obtained by coating the surface of the red phosphorus particles with a titanium-cobalt complex hydrated oxide, which is a hydrolysis product of soluble salts of titanium and cobalt, and an organic resin. be. The specific form of this stabilized red phosphorus is a two-layer structure in which a deposited coating layer of titanium-cobalt composite hydrated oxide is formed on the surface of red phosphorus particles, and an organic resin layer is formed on top of the deposited coating layer. or a single layer formed by depositing and coating a blend of titanium-cobalt composite hydrated oxide and organic resin on the surface of red phosphorus particles. It will be done. The precipitate of the titanium-cobalt complex hydrated oxide is thought to be TiO ₂ · nH ₂ O and Co · nH ₂ O, but since it is a coprecipitate, it is presumed that it is not a mere mixture of these. . In addition, the amount of titanium-cobalt composite hydrated oxide deposited on red phosphorus particles varies depending on the purpose of the stabilized red phosphorus, but in most cases it is 0.5 to 15% Ti+Co based on the total weight of red phosphorus particles. %,
It is also desirable that Co be in a range of 0.05% by weight or more, preferably 1 to 6% by weight, and Co in a range of 0.2% by weight or more. The reason for this is that at 0.5% by weight, the suppression of phosphine gas is incomplete, and at more than 15% by weight, it is inappropriate from a practical standpoint. In addition, the content of cobalt in the titanium-cobalt composite hydrated oxide is
It is preferable that Co is 0.05% by weight or more.
The reason for this is that if it is less than 0.05% by weight, the suppression of phosphine gas will be incomplete. Next, a thermosetting resin is used as the organic resin, and specific examples thereof include phenol resin, urea-formaldehyde resin, melamine resin, polyester resin, silicone resin, epoxy resin, polyamide resin, acrylic resin, etc. . In addition, the amount of red phosphorus deposited on the particle surface of organic resin varies depending on the type of organic resin and its purpose, but in most cases, the amount of red phosphorus deposited on the particle surface is
0.1 to 15% by weight, preferably 1 to 5% by weight. The reason for this is that if the amount is less than 0.1% by weight, the surface of the red phosphorus particles cannot be sufficiently covered due to the small amount of organic resin coating, and if it exceeds 15% by weight, the effect is saturated, which is not practical. It is inappropriate and inappropriate. The deposited coating amount of the organic resin is such that the stabilized red phosphorus obtained by coating has a two-layer structure consisting of a deposited coating layer of titanium-cobalt-based composite hydrated oxide and an organic resin layer on the red phosphorus particle surface. In some cases, it refers to the material used to form the organic resin layer, or in the case of a single-layer coating layer, it refers to the material contained in the blend of the titanium-cobalt complex hydrated oxide and the organic resin. The stabilized red phosphorus according to the present invention can be confirmed by microscopic observation to have a deposited coating formed on the particle surface, and can be easily identified in comparison with the original red phosphorus. The stabilized red phosphorus according to the present invention is a modified and stabilized red phosphorus that almost completely suppresses the generation of phosphine gas, but the details of the suppression mechanism are unknown. Furthermore, in the stabilized red phosphorus according to the present invention, the generation of phosphine gas is suppressed mainly by the combination of titanium and cobalt, and it is presumed that the organic resin has a supplementary effect such as increasing the mechanical strength of the skin. , it is not clear why the titanium-cobalt combination shows good results. This combination was discovered as a result of numerous experiments, and the combination of titanium and cobalt can produce unique effects that cannot be achieved when combined with other elements. Next, a method for producing stabilized red phosphorus according to the present invention will be explained. First, as a first method, red phosphorus is dispersed in a mixed salt aqueous solution of a titanium salt and a cobalt salt, and an alkali agent is added to the resulting aqueous suspension of red phosphorus while stirring to neutralize it. Adjust from .5 to 8.5.
After neutralization, heating is performed while stirring, and the resulting fine precipitates of titanium-cobalt complex hydrated oxide are deposited on the surface of red phosphorus particles, followed by separation and washing to produce titanium-cobalt coated red phosphorus slurry. get. A liquid organic resin is added to this titanium-cobalt coated red phosphorus slurry, the pH is adjusted as necessary, and the organic resin is cured by heating with stirring to form an organic resin layer on the surface of the red phosphorus particles. , separation and recovery, homogeneous and stable stabilized red phosphorus can be industrially advantageously produced. In the present invention, the aqueous suspension of red phosphorus is a mixed salt aqueous solution in which a predetermined amount of titanium salt and cobalt salt is dissolved in water in an amount of at least twice the amount of red phosphorus, preferably 5 to 10 times, by weight. It can be obtained by adding red phosphorus particles to the liquid under stirring. In this case, if the amount of water in the mixed salt aqueous solution is less than twice the amount of red phosphorus, the red phosphorus concentration becomes too high and stirring becomes impossible. In addition, as another method for preparing an aqueous suspension of red phosphorus, contrary to the above, a mixed salt aqueous solution of a titanium salt and a cobalt salt is added to a red phosphorus slurry prepared by dispersing red phosphorus in water in advance. mosquito,
Alternatively, an aqueous suspension can be obtained by adding and dissolving crystals of predetermined titanium salts and cobalt salts. However, if an aqueous solution or crystals of a mixed salt of titanium salt and cobalt salt is added to an alkaline slurry of red phosphorus, there is a risk that the red phosphorus will be hydrolyzed, so it is better to avoid this. Furthermore, the titanium salts and cobalt salts used in the preparation of the mixed salt aqueous solution can be used without particular limitation as long as they are water-soluble titanium and cobalt salts, but among them, sulfates and hydrochlorides are particularly suitable. or at least one selected from nitrates
More than one species is preferred. The concentration of the mixed salt aqueous solution of a titanium salt and a cobalt salt is not particularly limited, but may be equal to or lower than the solubility of each salt at room temperature. Any device can be used to prepare the aqueous suspension of red phosphorus as long as it can homogeneously disperse red phosphorus particles, but specifically, any desired means may be used as appropriate, such as normal stirring. It is desirable to use high-speed stirring or a shear dispersion device such as a colloid mill or homogenizer to prepare a suspension in a state of dispersion close to that of primary particles, with the agglomerates of red phosphorus particles removed as much as possible. Further, when dispersing the red phosphorus particles, a small amount of a dispersant such as a surfactant or sodium hexametaphosphate can be used as necessary to the extent that the coating conditions are not impaired. There is no particular reason to limit the concentration of red phosphorus in an aqueous suspension of red phosphorus, but it is often 50 g/~
A range of 500g/, preferably 70g/ to 300g/ is desirable; if it is less than 50g/, the slurry concentration will be low and the deposited coating concentration will decrease, making it uneconomical because the processing capacity will be large; if it exceeds 500g/, particles will This is not preferable because the dispersibility of the material becomes poor. In addition, in depositing and coating the red phosphorus particles in this aqueous suspension, the temperature is raised to effectively carry out the deposition process, but the temperature of the aqueous suspension is adjusted in advance before the deposition process. There is no problem in adding an alkaline agent and performing a deposition treatment after that. Alkaline agents include ammonia gas, aqueous ammonia, caustic soda, caustic potash, NaHCO ₃ ,
At least one selected from inorganic alkaline agents such as Na ₂ CO ₃ , K ₂ CO ₃ , KHCO ₃ , Ca(OH) ₂ , and organic alkaline agents such as ethanolamine is used; Ammonia gas and ammonia water are preferred because they can be easily removed by washing. The end point pH of neutralization needs to be set at a pH at which cobalt and titanium ions remain in the solution at the end of the deposition process. This pH varies depending on the combination of titanium salt and cobalt salt used, but the pH after the completion of the deposition treatment is 6 to 8, preferably 6 to 8.
It is desirable to fall within the range of 7.0±0.5 for complete coverage. In addition, heating lowers the PH by 1 to 1.5, so if you adjust the PH before heating, 6.5
The liquidity should be ~8.5, preferably 8.0±0.5. At this time, since red phosphorus is easily hydrolyzed in alkaline conditions, it is better not to exceed PH9. When an alkali agent is added to an aqueous suspension of red phosphorus, a precipitation reaction begins immediately, but the addition rate as well as the liquid concentration directly affect the reaction;
These factors are significantly related to the physical properties of red phosphorus, especially the surface characteristics, so after fully considering these factors, the addition rate of the alkaline agent should be set and controlled to avoid uneven deposited skin. It is necessary to add In many cases it is better to add gradually and quantitatively. As a result of neutralization under such stirring, fine precipitates of titanium-cobalt complex hydrated oxide are deposited on the surface of the red phosphorus particles, whether at room temperature or under heating, forming a uniform and firm deposited skin. is being formed. At this time, the thickness of the deposited film changes depending on the amount of titanium salt and cobalt salt present in the solution, so by adjusting this within the range that provides the above-mentioned coating amount, a coating suitable for various uses can be created. Can be set. Note that the slurry concentration during deposition is preferably 60°C or higher, more preferably in the range of 80 to 90°C. After the deposition process is completed, the mother liquor is separated by a conventional method, and the red phosphorus coated with the titanium-cobalt complex hydrated oxide is filtered, and if necessary, after washing with water, it is dispersed in water to obtain the titanium-cobalt composite hydrated oxide. Obtain a cobalt coated red rinse slurry. Next, a liquid organic resin, mainly a thermosetting resin, was added to the obtained titanium-cobalt coated red rinsing slurry in an amount that would be within the above coating amount range, and the pH was adjusted as necessary. The organic resin is cured by heating under stirring to form an organic resin layer on the surface of the red phosphorus particles. After the organic resin film is coated on the surface of the red phosphorus particles in this way, the red phosphorus particles are filtered by a conventional method, washed with water if necessary, and then separated and heated to be recovered. It should be noted that the use of an appropriate amount of auxiliary agents such as coupling agents and surfactants in forming the organic coating does not pose a problem and often gives favorable results. Next, as a second method, the stabilized red phosphorus particle surface is coated with a single layer of a mixture of a titanium-cobalt composite hydrated oxide and an organic resin. The method for producing phosphorus will be explained. In this method, a liquid organic resin is added to an aqueous mixed salt solution of a titanium salt and a cobalt salt, mixed uniformly, red phosphorus is uniformly dispersed, and the resulting aqueous suspension of red phosphorus is stirred. Add an alkaline agent to neutralize and adjust the pH to 6.5-8.5. After neutralization, heating is performed while stirring, and the resulting fine precipitates of titanium-cobalt composite hydrated oxide and organic resin are deposited on the red phosphorus particle surface at the same time, and then separated and recovered for industrial use. It is possible to advantageously produce homogeneous and stable stabilized red phosphorus. However, although this production method can produce a red phosphorus coating similar to the first method, its use is limited because impurities such as by-product ammonium chloride may remain in the coating. [Examples] Hereinafter, the present invention will be explained in more detail by showing examples. Example 1 Titanium tetrachloride solution (manufactured by Showa Denko Co., Ltd., as Ti
8.5wt%), 2.94g (5wt as Ti for red phosphorus)
%) and cobalt sulfate (reagent, manufactured by Kanto Kagaku Co., Ltd.,
CoSO ₄ .7H ₂ O) 0.073 g (0.3 wt% as Co relative to red phosphorus) was dissolved in 50 g of water. Add to this pre-washed red phosphorus (particle size 3-44μm,
Add 5g of average particle size 15μm) and add while stirring.
A 3wt% NH ₄ OH solution was added to adjust the pH to 7.0. Next, the mixture was heated to a temperature of 90 DEG C. and continued to be heated and stirred for 2 hours, and the filtered residue was washed with deionized water and then added to 50 g of water to obtain a titanium-cobalt coated red rinsing slurry. Phenol resin (manufactured by Gunei Chemical Co., Ltd.,
Add 0.5 g of Resitop PL-2771), heat and stir at 95℃ for 1 hour, filter, wash with water, and dry under reduced pressure (130℃,
5 hours) to obtain 5.6 g of stabilized red phosphorus. The test results for the stabilized red phosphorus obtained were as shown in Table 1. Example 2 A titanium-cobalt coated red rinsing slurry was obtained in the same manner as in Example 1. Add 0.6 g of epoxy resin (Epicoat 801, manufactured by Ciel Yuka Epoxy), 0.01 g of hardening agent (Versamide-150, manufactured by Henkel Hakusui), and 0.6 g of surfactant (Ionet S-20, manufactured by Sanyo Kasei) to this slurry, and add 5 wt. % phosphoric acid to pH 5. The mixture was heated to 60°C, separated after 2 hours, washed with water, and dried under reduced pressure at 110°C for 16 hours to obtain 5.5 g of stabilized red phosphorus. The test results for the stabilized red phosphorus obtained were as shown in Table 1. Example 3 A titanium-cobalt coated red rinsing slurry was obtained in the same manner as in Example 1. After adding 5wt% phosphoric acid to this slurry to adjust the pH to 3, 0.15g of melamine resin emulsion (Water Sol S-695, manufactured by Dainippon Ink Chemical) was added.
While stirring, the mixture was heated to 95°C and reacted for 1 hour. During the reaction, the pH of the solution was maintained at 3 by adding 5 wt% phosphoric acid. After the reaction was completed, the mixture was separated, washed with water, and dried under reduced pressure at 100°C for 16 hours to obtain 5.5 g of stabilized red phosphorus. The test results for the stabilized red phosphorus obtained were as shown in Table 1. Example 4 A titanium-cobalt coated red rinsing slurry was obtained in the same manner as in Example 1. After adding 5wt% phosphoric acid to this slurry and adjusting the pH to 3, a urea-formaldehyde resin emulsion (Polyfix UC-30M, manufactured by Showa Kobunshi) was added.
0.15 g was added, and the mixture was heated to 95° C. with stirring and allowed to react for 1 hour. During the reaction, 5wt% phosphoric acid was added to maintain the pH of the solution at 3. After the reaction was completed, the mixture was separated, washed with water, and dried under reduced pressure at 100°C for 16 hours to obtain 5.5 g of stabilized red phosphorus. The test results for the stabilized red phosphorus obtained were as shown in Table 1. Example 5 Titanium sulfate solution (as reagent Ti(SO ₄ ))
24.0wt%, manufactured by Kanto Kagaku Co., Ltd.) 5.2g (5wt% as Ti relative to red phosphorus) and cobalt sulfate (reagent,
Kanto Kagaku Co., Ltd.) 0.073g (as Co for red phosphorus)
0.3 wt%) and 0.5 g of phenolic resin (Regitop PL-2771, manufactured by Gunei Chemical Co., Ltd.) were dissolved in 50 g of water. To this, 5 g of red phosphorus powder with a particle size of 3 to 44 μm and an average particle size of 20 μm, which had been washed with water and vacuum dried (100°C), was added, and while stirring, 5 wt% ammonia aqueous solution was added, and the pH was adjusted to 7.5. did. Next, the mixture was heated with stirring to bring the temperature to 95°C, and heating and stirring were continued for 2 hours. Final PH at this time
was 6.8. After cooling, it was separated. The slag was washed with deionized water until the electrical conductivity of the liquid was 10 μs/cm or less, filtered, washed with water, and dried in a vacuum dryer at 130°C for 5 hours to obtain 6.2 g of stabilized red phosphorus. . The test results for the stabilized red phosphorus obtained were as shown in Table 1. Comparative Example 1 A titanium-cobalt coated red rinsing slurry was obtained in the same manner as in Example 1. This slurry was separated and dried under reduced pressure (130℃, 5
time) to obtain 5.5 g of stabilized red phosphorus. The test results for the stabilized red phosphorus obtained were as shown in Table 1. Comparative Example 2 A red phosphorus slurry was prepared by suspending 5 g of red phosphorus (particle size: 3 to 44 μm, average particle size: 15 μm), which had been washed in advance, in 50 g of water. Add 1 g of phenol resin (Resitop PL-2771, manufactured by Gunei Chemical Co., Ltd.) to this,
After heating and stirring at ℃ for 1 hour, the mixture was filtered, washed with water, and dried under reduced pressure (130 ℃, 5 hours) to obtain 5.5 g of stabilized red phosphorus.
The test results for the stabilized red phosphorus obtained were as shown in Table 1.

[Table] Measurement of the amount of Γphosphine generated.
Take 0.5g of the sample stored for a period of time and heat it in _N2 gas (150°C, 3 hours). The amount of _PH3 generated was measured using a gas chromatograph, and the amount of _PH3 generated per 1g of sample (μg) was determined.
Converted. Hot water resistance test of Γ-stabilized red phosphorus coating In an Erlenmeyer flask equipped with a reflux condenser,
1 g of the stabilized red phosphorus sample obtained in each of the Examples and Comparative Examples shown in the table and 180 ml of water were added and heated at a boiling state for 8 hours. Measure the PH and electrical conductivity of the supernatant before and after heating. [Effects of the Invention] As explained above, it has been found that the stabilized red phosphorus of the present invention exhibits heat decomposition resistance and hydrolysis resistance that were hitherto unimaginable. This titanium-cobalt composite coating and organic resin coating almost completely suppress the hydrolysis reaction of red phosphorus in the presence of moisture and at high temperatures, making it extremely useful as a flame retardant for various synthetic resins. I can do it.

Claims (1)

[Scope of Claims] 1. Stabilized red phosphorus, characterized in that the surface of red phosphorus particles is deposited and coated with a titanium-cobalt complex hydrated oxide and an organic resin. 2. The stabilized red phosphorus according to claim 1, wherein a deposited coating layer of a titanium-cobalt composite hydrated oxide is formed on the surface of the red phosphorus particles, and an organic resin layer is formed thereon. 3. The stabilized red phosphorus according to claim 1, wherein a deposited coating layer comprising a titanium-cobalt composite hydrated oxide and an organic resin is formed on the surface of the red phosphorus particles. 4. The amount of red phosphorus deposited on the particle surface is 0.5 to 15% by weight of titanium-cobalt composite hydrated oxide as Ti + Co, and 0.05% by weight or more of Co, and organic resin based on the total weight of red phosphorus particles. The amount is 0.1~
Stabilized red phosphorus according to claim 1, 2 or 3, which is 15% by weight. 5. A fine precipitate of titanium-cobalt complex hydrated oxide produced by adding an alkaline agent to an aqueous suspension of red phosphorus dispersed in an aqueous mixed salt solution of a titanium salt and a cobalt salt to neutralize it. A method for producing stabilized red phosphorus, which comprises depositing the surface of phosphorus particles and simultaneously or subsequently coating the surface with an organic resin. 6 The deposition treatment of titanium-cobalt composite hydrated oxide on the surface of red phosphorus particles is performed until the final pH of the reaction system is 6.
8. The method for producing stabilized red phosphorus according to claim 5, wherein the method is carried out at a temperature of 60° C. or higher.