JP2835955B2 - Stabilized red phosphorus and method for producing the same - Google Patents

Description

The present invention relates to stabilized red phosphorus and a method for producing the same,
More specifically, a stabilized red phosphorus characterized by forming a co-precipitated coating layer of a composite hydroxide of titanium and aluminum on the surface of red phosphorus, and coating and forming a thermosetting resin thereon. It relates to a manufacturing method.

The stabilized red phosphorus according to the present invention is useful as a flame retardant for synthetic resins, and can be used in the fields of resins, paints and adhesives. Particularly, the moisture resistance and corrosion resistance useful as a flame retardant for an epoxy resin for high-voltage electronic components have been improved, and it can be used in the field of electronic materials.

[Prior Art] It is well known that red phosphorus imparts an excellent flame retardant effect to a synthetic resin, and is actually used as a flame retardant.

However, when red phosphorus is used as it is, it reacts with water to cause a hydrolysis reaction accompanied by generation of phosphine gas. Therefore, conventionally, red phosphorus is coated with an organic or inorganic material and used as modified red phosphorus. And 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 [Gomerin, Handbook del Anorganicien Chemie], 8th edition (1964), “Phosphorus”, Part B, p. 83 (Gmelin. Handbuch der anorganishen Chemie '' 8th E
dition (1964), vol Phosphorus, Parts B. Page 83)].

However, this method of modifying red phosphorus requires a large amount of aluminum hydroxide to be coated for safe stabilization of red phosphorus, so that not only the effect as a red phosphorus flame retardant is reduced, but also depending on the application. May have adverse effects.

Other examples of the method for modifying red phosphorus include a method of coating aluminum hydroxide and a hydroxide of zinc or magnesium in combination (U.S. Pat. No. 2,635,953), and a method of coating with a thermosetting resin. High-quality red phosphorus (JP-A-51-105996), modified red phosphorus (JP-A-52-125489) in which the surface of red phosphorus is converted to a metal phosphide and then coated with a thermosetting resin.
Modified red phosphorus whose red phosphorus surface is coated with a hydrated oxide of titanium (US Pat. No. 4,442,782), or red phosphorus whose surface is coated with a hydrated oxide of titanium and further coated with a thermosetting resin Coated modified red phosphorus and the like have been proposed.

[Problems to be Solved by the Invention] As described above, many proposals have been made for stabilization by reforming red phosphorus, but each has advantages and disadvantages and still has some important problems. In particular, red phosphorus is easily hydrolyzed in the presence of water, and accompanied by the generation of odorous and toxic phosphine gas even in a very small amount, and it has been extremely difficult to completely control the generation of this gas.

For this reason, it has been proposed to suppress the generated phosphine gas by coexisting a metal having a high affinity with the phosphine gas, for example, a heavy metal such as copper or nickel. However, many heavy metals promote the hydrolysis of red phosphorus. As a result, the moisture resistance is reduced and the generation of phosphine gas is promoted.

In addition, in electric parts processed by adding these modified red phosphorus to epoxy resin or the like, the presence of a small amount of moisture gradually changes the quality over a long period of time to produce phosphorus oxides, which result in poor insulation, corrosion, etc. In addition, the performance of the electronic component may be deteriorated.

The present invention substantially suppresses generation of phosphine gas accompanying the decomposition of red phosphorus, and at the same time, seeks various stabilization methods to obtain stabilized red phosphorus excellent in moisture resistance and corrosion resistance, and conducts earnest research. As a result, a co-precipitated coating layer of a composite hydroxide of titanium and aluminum was formed on the red phosphorus particles, and a thermosetting resin coating was applied thereon. As a result, a surprisingly stable red phosphorus powder was obtained. That is, the present invention was completed.

[Means for Solving the Problems] and [Action] That is, the present invention forms a co-precipitated coating layer of a composite hydroxide of titanium and aluminum on the surface of red phosphorus particles, and further forms a thermosetting resin thereon. A stabilized red phosphorus characterized by being formed by coating.

Further, the present invention provides a composite hydrated oxidation of titanium and aluminum formed by adding an alkali agent to an aqueous suspension of red phosphorus dispersed in a mixed aqueous solution of a titanium salt and polyaluminum chloride and neutralizing the resultant. The present invention relates to a method for producing stabilized red phosphorus, comprising depositing a fine coprecipitate of the substance on the surface of red phosphorus particles, and then coating the same with a thermosetting resin.

 Hereinafter, the present invention will be described in detail.

The red phosphorus particles in the present invention are at most 100 μm or less, preferably 44 μm or less, and have an average particle diameter of 5 to 30 μm, preferably 10 to 20 μm. Further, the fine powder increases the surface area of the particles and tends to be unstable, so that those having a particle size of about 1 μm or less should be cut as much as possible.

Therefore, the particles of red phosphorus in the present invention are preferably substantially in the range of 1 to 100 μm in particle diameter.
5% by weight or less of those with μm or less and 100μm or more
The following are desirable:

The particle size and the average particle size indicate values measured by a sieving method or a Coulter counter method.

The stabilized red phosphorus according to the present invention comprises, on the surface of the red phosphorus particles, a coprecipitation coating layer of a composite hydroxide of titanium and aluminum, which is a hydrolysis product of a soluble salt of titanium and polyaluminum chloride, and A coating layer having a double structure is formed by coating a thermosetting resin.

The coprecipitate of the composite hydroxide of titanium and aluminum is considered to be TiO ₂ .xH ₂ O, (Al ₂ O ₃ .yH ₂ O) m. Not a mixture.

The amount of the co-precipitated coating of the composite hydroxide of titanium and aluminum on the red phosphorus particles varies depending on the use of the stabilized red phosphorus, etc., but in many cases, 0.5 to 15% of the total weight of the red phosphorus particles is expressed as Ti + Al. % By weight and Al is 0.05% by weight or more, preferably Ti + Al is 1.0 to 6% by weight and Al is 0.2% by weight.
It is desirably in the range of not less than% by weight. The reason for this is
If Ti + Al is less than 0.5% by weight, the suppression of phosphine gas is insufficient, and if it exceeds 15% by weight, it is inappropriate from a practical standpoint. On the other hand, if Al is less than 0.05% by weight, the suppression of phosphine gas becomes incomplete.

Next, specific examples of the thermosetting resin include phenol resin, urea-formaldehyde resin, melamine resin, polyester resin, silicone resin, epoxy resin, polyamide resin, and acrylic resin.

Also, the amount of red phosphorus deposited on the particle surface of the thermosetting resin varies depending on the type and use of the thermosetting resin,
In most cases, 1 to 30% by weight based on the total weight of red phosphorus particles,
Preferably, the content is 5 to 20% by weight. The reason for this is 1.0
If the amount is less than 30% by weight, the surface of the red phosphorus particles cannot be sufficiently coated due to the small amount of the thermosetting resin, and if the amount exceeds 30% by weight, the effect is saturated and is not practical from an economic viewpoint. Improper.

The deposited coating amount of the thermosetting resin, the stabilized red phosphorus obtained by coating is composed of a co-deposited coating layer of a composite hydroxide of titanium and aluminum on the particle surface of red phosphorus and a thermosetting resin layer. What is used for forming a thermosetting resin layer having a two-layer structure is shown.

The stabilized red phosphorus according to the present invention can be confirmed by microscopic observation that a deposited coating is formed on the particle surface, and can be easily distinguished from the original red phosphorus.

The stabilized red phosphorus according to the present invention is a reformed and stabilized red phosphorus in which generation of phosphine gas is almost completely suppressed, but the details of the structure for suppressing red phosphorus are unknown.

In addition, the stabilized red phosphorus according to the present invention suppresses the generation of phosphine gas mainly by a combination of a composite hydroxide of titanium and aluminum, and the thermosetting resin increases the mechanical strength of the film, such as a supplement. In addition to acting, an important effect is expected to improve the water resistance of the stabilized red phosphorus. It is not clear why the combination of the composite hydroxide of titanium and aluminum shows good results. This combination has been found from numerous experimental results, and a unique effect that cannot be achieved when combined with other elements can be obtained with the combination of the composite hydroxide of titanium and aluminum.

Next, a method for producing stabilized red phosphorus according to the present invention will be described.

In the production method of the present invention, red phosphorus is dispersed in an aqueous solution of a mixed salt of a titanium salt and polyaluminum chloride, and the resulting red phosphorus suspension is neutralized by adding an alkali agent with stirring to obtain a pH 6.5. Adjust to ~ 8.5. After the neutralization, the mixture is further heated with stirring, and the resulting fine coprecipitate of the composite hydroxide of titanium and aluminum is deposited on the surface of the red phosphorus particles. A composite hydroxide coated red phosphorus slurry is obtained. A liquid thermosetting resin is added to the composite hydroxide coating slurry of titanium and aluminum, the pH is adjusted if necessary, and then the mixture is heated under stirring to cure the thermosetting resin, and the surface of the red phosphorus particles is cured. After forming a thermosetting resin layer on the substrate, separation and recovery can be carried out industrially to produce a homogeneous and stable stabilized red phosphorus.

In the present invention, the aqueous suspension of red phosphorus is, by weight,
It is prepared by adding red phosphorus particles to a mixed salt aqueous solution obtained by dissolving a predetermined amount of a titanium salt and polyaluminum chloride in water at least twice the amount of red phosphorus, preferably 5 to 10 times the amount of water, with stirring. Can be obtained. In this case, if the amount of the mixed salt aqueous solution is less than twice the amount of red phosphorus, the concentration of red phosphorus is so high that stirring becomes impossible.

Also, as another method of preparing an aqueous suspension of red phosphorus,
Contrary to the above, a mixed aqueous solution of titanium salt and polyaluminum chloride is added to a red phosphorus slurry prepared by dispersing red phosphorus in water in advance, or predetermined titanium salt and polyaluminum chloride crystals are added. By dissolving in this manner, an aqueous suspension can be obtained.

However, if an aqueous solution or crystal of a mixed salt of a titanium salt and polyaluminum chloride is added to an alkaline slurry of red phosphorus, there is a risk that the red phosphorus is hydrolyzed.

The titanium salt used for preparing the mixed salt aqueous solution can be used without particular limitation as long as it is a water-soluble titanium salt. Among them, sulfate,
At least one selected from hydrochloride and nitrate is desirable.

The concentration of the mixed salt aqueous solution of the titanium salt and the polyaluminum chloride does not need to be particularly limited, but may be the solubility of each salt at room temperature or less.

The equipment used to prepare the aqueous suspension of red phosphorus includes:
Any device can be used as long as it can uniformly disperse the red phosphorus particles.Specifically, any desired means, for example, a low-speed stirring to a high-speed stirring, or a shear dispersing device such as a colloid mill or a homogenizer can be used. It is desirable to prepare a suspension in a dispersed state close to the primary particles from which agglomerates of red phosphorus particles are removed as much as possible.

In dispersing the red phosphorus particles, for example, a small amount of a surfactant or a dispersant such as sodium hexametaphosphate can be used as needed so as not to impair the coating conditions.

The concentration of red phosphorus in the aqueous suspension of red phosphorus is not particularly limited, but in many cases, the range is preferably 50 g /, to 500 g /, preferably 70 g / to 300 g /, and if less than 50 g / slurry. Since the concentration is low and the sediment coating concentration is low, the treatment capacity is large, which is uneconomical. If it exceeds 500 g /, the dispersibility of the red phosphorus particles deteriorates, which is not preferable.

When depositing and coating the red phosphorus particles in the aqueous suspension, the temperature is raised in order to carry out the deposition treatment effectively, but the temperature of the aqueous suspension is adjusted in advance before the deposition treatment. Thereafter, an alkali agent may be added to perform the deposition treatment, and there is no problem.

As the alkaline agent, ammonia gas, aqueous ammonia,
At least one selected from inorganic alkali agents such as caustic soda, caustic potash, sodium bicarbonate, sodium carbonate, potash bicarbonate, slaked lime, and organic alkali agents such as ethanolamine is used. Ammonia gas and aqueous ammonia, which are easy to produce, are preferred.

As the end point pH of the neutralization, it is necessary to set a pH at which titanium and aluminum ions remain in the solution at the end of the deposition treatment. This pH varies depending on the combination of the titanium salt and polyaluminum chloride used, but it is desirable that the liquid property at the end of the deposition treatment falls within the range of 6 to 8, preferably 7.0 ± 0.5 for complete coating. Further, since the pH is lowered by 1 to 1.5 by heating, when the pH is adjusted before heating, the pH is adjusted to 6.5 to 8.5, preferably 8.0 ± 0.5. At this time, the pH should not exceed 9 because red phosphorus is easily hydrolyzed in alkaline conditions.

When an alkali is added to an aqueous suspension of red phosphorus, the precipitation reaction starts immediately. At this time, the addition rate directly affects the reaction with the concentration of the solution, and these factors are related to the physical properties of red phosphorus, especially the surface Since these factors are significantly related to the characteristics, it is necessary to set, control, and add the addition rate of the alkali agent in consideration of these factors so as not to cause unevenness of the deposited film. In many cases, it is better to add the solution gradually and quantitatively. The coprecipitation of the composite hydroxide of titanium and aluminum is deposited on the surface of the red phosphorus particles, and the uniform and strong deposited film is formed at either room temperature or heating with the neutralization under such stirring. It is being done. At this time, since the thickness of the deposited film changes according to the amount of titanium salt and polyaluminum chloride in the liquid, by adjusting this in the range so as to become the above-mentioned coating amount,
Coatings can be set for various applications.

Incidentally, the slurry temperature during the deposition is preferably 60 ° C.
As described above, the temperature is more preferably in the range of 80 to 90 ° C.

After completion of the deposition treatment, the mother liquor was separated by a conventional method, and red phosphorus coated and coated with a composite hydroxide of titanium and aluminum was filtered, further washed with water as needed, and then mixed with titanium dispersed in water. A composite hydroxide-coated red phosphorus slurry with aluminum is obtained.

Then, a liquid thermosetting resin is added to the obtained composite hydroxide-coated red phosphorus slurry of titanium and aluminum in such an amount as to fall within the above-mentioned coating amount, and a treatment according to the curing conditions of the resin is performed. After the application, the mixture is heated under stirring to cure the thermosetting resin to form a thermosetting resin layer on the surface of the red phosphorus particles.

In this way, after coating the film of the thermosetting resin on the surface of the red phosphorus particles, filtration by a conventional method, washing with water as necessary,
Separation, heat treatment and recovery.

In addition, it is unavoidable to use an appropriate amount of an auxiliary agent such as a coupling agent or a surfactant in the organic coating, and in many cases, a favorable result is obtained.

EXAMPLES Hereinafter, the present invention will be further described with reference to Examples.

Example 1 Titanium sulfate solution (24.0 wt% as reagent Ti (SO ₄ ) ₂ )
%, Manufactured by Kanto Chemical Co., Ltd.) 5.22 g or titanium tetrachloride solution (T
2.94 g (5 wt% as Ti with respect to red phosphorus) containing 8.5 wt% as i and 0.57 g as polyaluminum chloride (trade name, Tieback, manufactured by Daimei Chemical Co.) with 2.0 as Al as red phosphorus wt%) was dissolved in 50 g of water.

5 g of red phosphorus (particle size: 3-44 μm, average particle size: 15 μm) washed in advance with water was added thereto, and the pH was adjusted to 7.0 by adding a 3 wt% NH ₄ OH solution with stirring.

Next, the mixture was heated to a temperature of 90 ° C., and heated and stirred for 2 hours. After filtration and washing, the coated red phosphorus was poured into 50 g of water to obtain a composite hydroxide-coated red phosphorus slurry of titanium and aluminum.

To this slurry was added 0.5 g of a phenolic resin (manufactured by Gunei Chemical Co., Ltd., Retop PL-2771), and after heating and stirring at 95 ° C for 1 hour,
Filtration, washing and drying under reduced pressure (130 ° C., 5 hours) gave 5.6 g of stabilized red phosphorus. The test results of the stabilized red phosphorus obtained were as shown in Table 1.

Example 2 A red hydroxide slurry coated with a composite hydroxide of titanium and aluminum was obtained in the same manner as in Example 1.

To this slurry, 0.5 g of epoxy resin (manufactured by Shell Oil Epoxy, Epicoat 801) and a surfactant (manufactured by Sanyo Chemical,
0.5 g of Ionette S-20) and a curing agent (made by Henkel Hakusui,
Versamide-150) (0.25 g) was added to adjust the pH to 5 with 5 wt% phosphoric acid.

After heating to 60 ° C and heating and stirring for 2 hours, filtration, washing,
Drying under reduced pressure at 110 ° C for 16 hours gave 5.5 g of stabilized red phosphorus. The test results of the stabilized red phosphorus obtained were as shown in Table 1.

Example 3 By operating in the same manner as in Example 1, a red phosphorus slurry coated with a composite hydroxide of titanium and aluminum was obtained.

5 wt% phosphoric acid was added to the slurry to adjust the pH to 3, and 0.5 g of a melamine resin emulsion (Water Sol S-695, manufactured by Dainippon Ink and Chemicals, Inc.) was added. The mixture was heated and stirred at 95 ° C. and reacted for 1 hour. During the reaction, pH was maintained at pH 3 by adding 5 wt% phosphoric acid as needed.

After the completion of the reaction, filtration, washing and drying under reduced pressure at 110 ° C. were performed for 16 hours to obtain 5.5 g of stabilized red phosphorus. The test results of the stabilized red phosphorus obtained were as shown in Table 1.

Example 4 A red hydroxide slurry coated with a composite hydroxide of titanium and aluminum was obtained in the same manner as in Example 1.

5 wt% phosphoric acid was added to the slurry to adjust the pH to 3, and 0.5 g of a urea-formaldehyde resin emulsion (Polyfix US-30M, manufactured by Showa Polymer Co., Ltd.) was added. During the reaction, pH was maintained at pH 3 by adding 5 wt% phosphoric acid as needed.

After completion of the reaction, filtration, washing with water and drying under reduced pressure at 100 ° C. were performed for 16 hours to obtain 5.5 g of stabilized red phosphorus. The test results of the stabilized red phosphorus obtained were as shown in Table 1.

Comparative Example 1 A red phosphorus slurry coated with a composite hydroxide of titanium and aluminum was obtained in the same manner as in Example 1.

This slurry was filtered, washed and dried under reduced pressure (130 ° C, 5
Time) to obtain 5.5 g of stabilized red phosphorus. The test results of the stabilized red phosphorus obtained were as shown in Table 1.

Comparative Example 2 Red phosphorus (particle size: 3 to 44 μm, average particle size: 15
μm) was suspended in 50 g of water to prepare a red phosphorus slurry. Add phenolic resin (Gunei Chemical,
PL-2771) 0.1 g was added, and the mixture was heated and stirred at 95 ° C for 1 hour, filtered, washed with water, dried under reduced pressure (130 ° C, 5 hours), and stabilized red phosphorus.
5.5 g were obtained. The test results of the stabilized red phosphorus obtained were as shown in Table 1.

○ Measurement of the amount of phosphine generated 0.5 g of a sample stored for 48 hours in a thermo-hygrostat at a temperature of 30 ° C. and a relative humidity of 83% is collected and heated in N ₂ gas (150 ° C., 3 hours).

The amount of generated phosphine was measured by gas chromatography, and was converted to the amount of generated phosphine per 1 g of the sample.

○ Heat resistance test of coating of stabilized red phosphorus In a conical flask equipped with a reflux condenser, a sample of the stabilized red phosphorus obtained in each of the examples and comparative examples shown in Table 1 above.
1 g and 180 ml of water were added and heated for 8 hours in a boiling state. The pH and electric conductivity of the supernatant before and after heating are measured.

[Effects of the Invention] As described above, it has been found that the stabilized red phosphorus of the present invention exhibits heat decomposition resistance and hydrolysis resistance that have not been considered before. Red phosphorus, which is further coated with a thermosetting resin on the composite hydroxide coating layer of titanium and aluminum, is capable of almost completely suppressing the hydrolysis reaction in the presence of moisture. It is extremely useful as a flame retardant.

Continuation of front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C01B 25/00

Claims (4)

(57) [Claims] 1. A stabilized red color, comprising forming a coprecipitated coating layer of a composite hydroxide of titanium and aluminum on the surface of red phosphorus particles and coating a thermosetting resin thereon. Rin. 2. The amount of red phosphorus deposited on the particle surface is 0.5 to 15% by weight, based on the total weight of red phosphorus particles, of a composite hydrated oxide of titanium and aluminum, Ti + Al, and 0.05% by weight of Al. %, And the amount of the thermosetting resin is 1 to 30% by weight. 3. A composite hydrated oxide of titanium and aluminum formed by adding an alkali agent to an aqueous suspension of red phosphorus dispersed in an aqueous mixed solution of a titanium salt and polyaluminum chloride and neutralizing the suspension. A method for producing stabilized red phosphorus, comprising depositing a fine coprecipitate on the surface of red phosphorus particles and coating the same with a thermosetting resin. 4. The co-precipitation treatment of a composite hydroxide of titanium and aluminum on the surface of red phosphorus particles is carried out in the final reaction system.
The method for producing stabilized red phosphorus according to claim 3, wherein the pH is 6 to 8 and the temperature is 60 ° C or higher.