JPH0454613B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for stabilizing red phosphorus against oxidation. BACKGROUND OF THE INVENTION It is known that when red phosphorus is stored in a humid atmosphere, it undergoes chemical reactions to form phosphine and various phosphoric acids, primarily phosphorous and phosphoric acids. The formation of highly toxic phosphine makes working conditions very hazardous and produces unpleasant odors, and the formation of phosphorous and phosphoric acids is undesirable when using red phosphorus. [Problems to be Solved by the Invention] Aluminum in the form of hydroxide has been widely used to prevent the deterioration of red phosphorus as described above and to stabilize red phosphorus. However, relatively large amounts of aluminum are required to achieve substantial stabilization of red phosphorus. Another problem encountered in prior art aluminum processing is that the product is difficult to process. A layer of alumina is deposited on the red phosphorus particles in the aqueous dispersion of red phosphorus, and the treated red phosphorus is filtered and dried. Effective filtration of treated red phosphorus is difficult to achieve as a result of gelation of the aluminum hydroxide, and large amounts of water are retained by the aluminum hydroxide. Recently, stabilization of red phosphorus has been achieved by using less titanium dioxide or titanium phosphate than needed for aluminum hydroxide treatment, as described in U.S. Pat. No. 4,421,728. It has been found that red phosphorus produced and further processed can be easily and rapidly filtered. Another advantage of titania-treated red phosphorus is that the red phosphorus can be heated at temperatures up to 300°C without evaporating water, which makes the red phosphorus product suitable for plastics treated at high temperatures. It is suitable for addition to the class. U.S. Patent No. 4092460, U.S. Patent No. 4188813 and U.S. Patent No.
No. 4,208,317 discloses flame resistant plastic compositions using treated red phosphorus particles as a flame retardant. The red phosphorus particles are described as being coated with a coating polymer, which can be a melamine-formaldehyde resin, a phenolic resin or an epoxy resin, in an amount of 5 to 80% by weight of the red phosphorus particles; There is a general indication that metal oxides or salts can be present in the composition in amounts up to 100% by weight. Further, US Pat. No. 4,315,897 proposes a method for stabilizing red phosphorus against oxidation by simultaneously treating red phosphorus particles with aluminum hydroxide and a hardened epoxy resin. SUMMARY OF THE INVENTION According to the present invention, it has now been found that a combination of a certain amount of titanium in the form of titanium dioxide or titanium phosphate and an organic resin is particularly effective as a stabilizer for red phosphorus. I found this out surprisingly. In the present invention,
A delay in red phosphorus oxidation and inhibition of phosphine formation is achieved. According to one aspect of the invention, the present invention provides a red phosphorus-containing composition having a particle size of at most about 2 mm, containing from 0.05 to 1.0% by weight of titanium dioxide or titanium phosphate and from 0.1 to 1.0% by weight of an organic resin.
The present invention provides a red phosphorus-containing composition characterized in that the red phosphorus particles contain 5.0% by weight and have a particle size of at most about 2 mm. According to the present invention, when using a combination of TiO ₂ and an epoxy resin, the improvement achieved in stability against oxidation is considerably greater than that achieved using the prior art combination of aluminum hydroxide and an epoxy resin. It becomes something big. The present invention also encompasses a novel method of processing red phosphorus particles to achieve stabilization of the red phosphorus particles. Therefore, according to another aspect of the present invention, a titanium compound is added to an aqueous slurry of red phosphorus particles in which the red phosphorus particles have a particle size of at most about 2 mm: an alkali is added to the slurry. Adjust the pH of the slurry to 2 to 4 and deposit titanium dioxide or titanium phosphate in an amount of about 0.05 to about 1.0% by weight as Ti on the red phosphorus particles; and depositing the resin on the red phosphorus particles in an amount of about 0.1 to about 5.0% by weight;
The present invention provides a method for preparing a red phosphorus-containing composition having a particle size of at most 2 mm, which comprises separating treated red phosphorus particles from a slurry. [Function] The organic resin used in the red phosphorus treatment according to the present invention is water-soluble or water-emulsifiable. One type of organic resin used in the present invention is an epoxy resin. Epoxy resins are thermosetting resins based on the reactivity of epoxy groups. One common type of resin is made from epichlorohydrin and aromatic and aliphatic polyols such as 2,2-bis-(4-hydroxylphenyl)-propane (bisphenol A), It has an ether terminal group, contains a large number of hydroxyl groups, and is easily cured using water-soluble internally modified polyamines. Curing typically occurs in an aqueous phase with a pH maintained at about 5-9 at temperatures of about 20°C to about 90°C. Epoxy resins that can be used in the present invention typically have an epoxy equivalent weight of about 170-500. Another type of organic resin used in this invention is melamine-formaldehyde resin. melamine
Formaldehyde resin is an amino resin made from melamine and formaldehyde. The first step in forming a melamine-formaldehyde resin is the formation of trimethylolmelamine, a molecule with a ring of three carbon atoms and three nitrogen atoms. Molecules of trimethylolmelamine or polymers of melimethylolmelamine are reacted with formaldehyde. Low molecular weight uncured melamine resins are water soluble syrups and are suitable for use in the present invention. Curing occurs with heat and acidity. Another type of organic resin used in this invention is urea-formaldehyde resin. Urea-formaldehyde resins are another class of amino resins that involve first forming a methylol urea and then thermally curing it by controlling heat and pressure in the presence of an acid catalyst. Formed by manipulation. The red phosphorus treated according to the present invention is at most 2 mm
, preferably in the form of particulates with dimensions of 0.01 to 0.15 mm. Red phosphorus particles are treated with titanium dioxide or titanium phosphate and an organic resin. The amount of titanium compound used is approximately 0.05 expressed as Ti.
to about 1.0% by weight, and the amount of organic resin can vary from 0.1 to 5% by weight, preferably from 0.5 to 3.0%.
% by weight. In view of the prior art, it is surprising that small amounts of titanium and organic resins as described above can effectively stabilize red phosphorus against oxidation and phosphine formation. Treatment of red phosphorus particles with titanium dioxide or titanium phosphate and an organic resin is carried out in two steps: first the titanium dioxide or titanium phosphate is deposited on the red phosphorus particles, and then the organic resin is deposited on the red phosphorus particles. be able to. Treatment of red phosphorus with titanium dioxide can be carried out in the aqueous phase to deposit hydrated titanium dioxide on the red phosphorus. In this operation, the red phosphorus particles are preferably suspended in water and the resulting slurry is heated at a temperature of about 60°C to about 90°C, preferably about 80°C to about 90°C.
Heat to ℃. The heated slurry is heated in a slightly acidic
Gradually mix with the required amount of water-soluble titanium salt, e.g. titanium sulfate, to achieve the desired treatment level at PH. An alkali is then added to the slurry to adjust the pH of the slurry to a range of about 2 to about 4 to deposit hydrated titanium dioxide onto the red phosphorus particles. The slurry is then treated with an organic resin. The method and conditions for organic resin treatment depend on the form and nature of the resin used to treat the red phosphorus particles. The resin is usually added to the slurry in uncured or partially cured form and is cured on the surface of the red phosphorus particles. If the organic resin is an epoxy resin, an aqueous dispersion of uncured epoxy resin in an amount sufficient to provide the desired treatment level is mixed with a slurry of red phosphorous treated with a titanium compound, followed by an aqueous solution of an epoxy hardener. Add to slurry. The pH of the slurry is approximately 4.
to about 6° C. and the slurry to about 40° C. to about 80° C.
C., preferably from about 50.degree. C. to about 65.degree. C., for a period of time to permit crosslinking, usually from about 0.5 to about 2 hours. After that, the pH of the slurry is again about 7-8.
to complete crosslinking in about 10 minutes to about 30 minutes. When the organic resin is melamine-formaldehyde resin, an aqueous solution of thermosetting uncured melamine-formaldehyde resin is added to the slurry of red phosphorus particles treated with a titanium compound, and the pH of the slurry is adjusted to about 2.5.
Adjust to ~4. Next, the slurry is heated to about 80℃~approx.
Heat to 100°C and heat cure the resin for about 0.5 to about 2 hours. If the organic resin is a urea-formaldehyde resin, an aqueous solution of uncured urea-formaldehyde resin is added to the slurry of red phosphorous particles treated with a titanium compound. Adjust the pH of the slurry to about 2.5 to about 4.0, heat the slurry to about 80℃ to about 100℃, and
The resin is cured for 0.5 to about 2 hours. Treatment of red phosphorus particles with titanium phosphate is similar to that described above for depositing titanium dioxide, except that orthophosphoric acid or a water-soluble salt of orthophosphoric acid such as sodium dihydrogen phosphate and titanium sulfate is added to the slurry rather than titanium sulfate alone. It can be carried out in the aqueous phase in a similar manner to the aqueous phase treatment. After titanium phosphate deposition, the slurry is treated with an organic resin as described above for titanium dioxide treatment. After completion of the resin deposition step, the treated red phosphorus is separated, for example by filtration, washed with water, dried and dehydrated in a vacuum oven at temperatures of about 100°C to about 130°C. Red phosphorus treated with a specific amount of titanium dioxide or titanium phosphate and a specific amount of organic resin using the present invention has improved properties compared to the prior art. Red phosphorus treated with titanium dioxide and epoxy resin has greater stability against degradation from the formation of oxidation products and phosphine than red phosphorus treated with titanium alone at the same concentration level; The same stability as when treated alone can be achieved with less titanium dioxide by using a combination of titanium dioxide and resin. Improved stability reduces acid formation and reduces phosphine generation during storage of treated red phosphorus.
It is clear that the presence of titanium dioxide or titanium phosphate on the red phosphorus contributes to a large extent to the low acid formation, and also the presence of organic resins on the red phosphorus contributes to a large extent to the low phosphine formation. That is clear. Although red phosphorus treated with titanium dioxide and melamine resin has lower stability than red phosphorus treated with titanium dioxide and epoxy resin, it has a good water content, which is advantageous for certain uses of red phosphorus, such as in the Matsushi industry. It has decentralized properties. Red phosphorus treated according to the present invention requires only a very short time for filtration and exhibits a much lower water retention capacity than red phosphorus treated with aluminum hydroxide, resulting in a process that, unlike aluminum hydroxide treatment, significantly reduces the time required for [Example] The present invention will be further explained by giving examples (hereinafter simply referred to as "examples" unless otherwise specified) below. Example 1 This example illustrates the stabilization of red phosphorus by a combination of titanium dioxide and epoxy resin. Amorphous red phosphorus (RAP), typically with a particle size of 0.15 to 0.01 mm, is suspended in water at a concentration of 25 g of red phosphorus in 100 ml of water and heated to 60° C. with stirring. Adding various amounts of titanium sulfate to samples of slurry;
The pH of the slurry was adjusted to 3 by adding 1.0N NaOH to form a precipitate of hydrated titanium dioxide on the red phosphorus. In this example, the amount of _TiO2 deposited is expressed as ppm of Ti in _TiO2 . The aqueous dispersion of uncured epoxy resin was then mixed with the suspension of red phosphorous particles and the solution of epoxy resin and curing agent was added. The epoxy resin used is a trade name, DE from Chemroy Chemicals Ltd.
It is an epoxy resin sold as R.324. This resin is DER331 epoxy resin and _C12 ~
It is a mixture of aliphatic reactive diluents that are _C14 aliphatic glycidyl ethers. DER324 is 197~
It has an epoxy equivalent weight of 206 and a viscosity of 600-800 cps at 25°C. DER331 is a reaction product of bisphenol A and epichlorohydrin, with a temperature of 182~
190 weight epoxy equivalent and 11000-14000cps at 25℃
It has a viscosity of The resin was used in the form of an emulsion in water (3 g of resin in 50 ml of water) with the addition of 1% of the surfactant Tween 20 (sorbitol monostearate). The hardening agent is Henkel.
The curing agent was designated TSXII-548 by Henkel & Co. The curing agent TSXII-548 is an aliphatic amidoamine water reducing agent with an amine value of 385-410 and was used in the form of an aqueous dispersion (3 g of amine in 50 ml of water). Next, 5% by weight of NaOH was added to adjust the pH to 5.
The suspension was stirred at 60°C for 1 hour. Next, 5% by weight
NaOH was added to raise the pH to 7 and the mixture (suspension) was stirred for an additional 15 minutes to crosslink the resin,
A coating was formed on the RAP particles. The mixture was then filtered, and the filter residue was washed with water and dried in a vacuum oven at about 100° C. for about 16 hours. The stability of the treated red phosphorus samples was tested and the results were compared to the stability of untreated red phosphorus, red phosphorus treated with resin only, aluminum hydroxide, red phosphorus treated with epoxy resin and red phosphorus treated with titanium dioxide only. compared with. Red phosphorus oxidation stability at 100% relative humidity
Tested by keeping the sample in an oven at a temperature of 70 °C under conditions of H ₃ PO ₄ by PH titration.
Measure the acidity expressed as . The results obtained are shown in the graph of FIG. The explanation is in Part I below.
Corresponds to the samples listed in the table. The results in Figure 1 show that red phosphorus treated with 1000ppmTi and a small amount of resin has almost the same stability against oxidation as that treated with 3000ppmTi, and is more stable than that treated with resin alone or with aluminum and resin. . The stability is further increased when 2000ppmTi and 3000ppmTi are combined with the resin, and is also more stable than TiO ₂ alone or Al(OH) ₃ in combination with the epoxy resin. The treated samples described above were also tested for phosphine generation and compared to untreated samples. sample
1 g each was stirred with water in a glass bottle (69 cm ³ ) equipped with a septum that could be directly inserted with a syringe. After repeated stirring and standing at room temperature, the phosphine concentration was measured by gas chromatography using a flame spectrometer detector. The obtained results are listed in the following Table I (However, in Table I, Sample 3,
4, 6, ~10, and 12 are examples, and samples 1, 2,
5 and 11 are comparative examples, sample 13 is a control example):

[Table] Resin ⁽¹⁾

Table I As can be observed from the results in Table I, phosphine generation is greatly reduced by treatment with amorphous red phosphorus, either alone or in combination with Ti or Al. The generation of phosphine is lower in the resin treated sample than in the Ti alone treated sample. Example 2 This example illustrates the stability of amorphous red phosphorus when stored under humid conditions. After processing the red phosphorus, the procedure of Example 1 was repeated except that the red phosphorus was not dried. Oxidative stability and phosphine generation were determined as described in Example 1. The measured values of oxidation stability are blotted on the graph in Figure 2, and the measured values of phosphine generation are listed in the following table (however, in the table, Samples 3 and 4 are the Examples, Samples 2, 5 and 6 is a comparative example, sample 1 is a control example):

[Table] From the results shown in Figure 2, it can be observed that oxidative stability increases when titanium dioxide and epoxy resin are used in combination. The results in Table 2 show that treating wet samples with a combination of titanium dioxide and epoxy resin significantly reduces phosphine generation. Example 3 This example illustrates the stabilization of red phosphorus by a combination of titanium dioxide and melamine resin. Amorphous red phosphorus, typically with particle size between 0.15 and 0.01 mm, is suspended in water at a concentration of 20 g per 100 ml of water and stirred to form a 10% aqueous solution of TiOSO ₄ H ₂ SO ₄ H ₂ O 3.4
mixed with ml. Then add 1.0N NaOH and PH
I made it 3. Add a sufficient amount of a 10% aqueous solution of melamine resin to the mixture to obtain the desired treatment and
The PH is again adjusted to about 3 by addition of %H ₃ PO ₄ .
The suspension was heated to 95° C. with stirring, reacted for 1 hour, and filtered. During the curing of this resin, the PH was controlled at about 3. The filtration residue was washed with water and dried in a vacuum oven at 100°C for about 16 hours. The melamine resin used was manufactured by Monsanto under the trade name Scriptset 101.
It was a methylated melamine-formaldehyde resin sold as Scripset 101. This resin is purchased in the form of a 75% aqueous solution. This resin was a polycondensation product of melamine and formaldehyde. The samples were tested for oxidative stability and phosphine generation as described in Example 1, and the results were compared to those for samples treated with resin alone and untreated red phosphorus. The oxidation stability results for RAP treated with Scriptset 101 are blotted in the graphical representation of Figure 3 and also treated with Scriptset 101.
The phosphine generation data for RAP are listed in the table below (however, in the table, samples 1, 2, and 3
and 6 are examples, samples 4 and 5 are comparative examples, sample 7
is a control example):

[Table] From the results shown in Figure 3, RAP stabilized using TiO ₂ and melamine resin is stable against oxidation, but the resin alone is not very effective.
Phosphine generation was reduced by treatment with TiO ₂ and melamine resin compared to untreated RAP and treatment with resin alone. Example 4 This example illustrates the stabilization of red phosphorus by a combination of titanium dioxide and urea-formaldehyde resin. The procedure of Example 3 was repeated using two urea-formaldehyde resins, except that the PH was controlled during resin curing and phosphoric acid was used to adjust the PH to 2.9-3.0 as necessary. . The resin used is the trade name Resimene LTX-31 from Monsanto.
-61 and LTX-31-62.
LTX-31-61 has a minimum solids content of 98% at 25℃
It is a modified urea-formaldehyde resin with a viscosity of 1800 cps and a density of 1.14 g/ml at 25°C. LTX
-31-62 has a solid content of 93-97%, 1.09g/ml at 25℃
Modified urea with a density of 600 cps at 25°C
It is formaldehyde resin. Samples were tested for oxidative stability and phosphine generation as described in Example 1, and results were compared to samples treated with resin alone and untreated red phosphorus. The oxidation stability results are plotted on the graph in Figure 4, and the phosphine generation data are listed in the table below (however, samples 3 to 7 in the table are examples, and samples 1 and 2 are comparative examples. be):

[Front] Arrived.
As can be observed from the graphical results in Figure 4, the combination of TiO ₂ or titanium phosphate and urea-formaldehyde resin increases the stability;
It is more effective to use LTX-31-62 resin. Example 5 This example is a compilation of data from previous examples and some additional experimental results for purposes of comparison and to draw conclusions from the data. The data selected from the previous examples are listed in the table below (however, in the table, 1(3), 3(6), 3(2), 4(3) and 4
(6) is an example and the others are comparative examples):

[Table] The following conclusions can be drawn from the above data: (a) Treated with a combination of TiO ₂ and epoxy resin
The oxidative stability of RAP (stability against H ₃ PO ₄ formation) is improved by approximately 13 times when compared to RAP treated with resin alone, but Al(OH)
The combination of TiO ₂ and epoxy resin improves the oxidative stability by only about twice; (b) treated with the combination of TiO ₂ and melamine resin.
The stability of RAP is improved by about 8 times when compared to RAP treated with resin alone; (c) The stability of RAP treated with the combination of TiO ₂ and urea-formaldehyde resin is improved compared to that treated with resin alone. (d) The treatment of RAP with TiO ₂ and epoxy resin gives the best all-round results with the best stability against oxidation and the least amount of phosphine. (e) Treatment of RAP with resins in general and epoxy resins in particular reduces the amount of phosphine generated; (f) TiO ₂ and Al(OH) ₃ stabilize RAP against oxidation, but TiO ₂ Al to RAP treated with
Addition of (OH) ₃ does not improve the stability of RAP. To summarize the disclosure herein, the present invention provides a novel amorphous red phosphorus with improved oxidative stability and phosphine generation by treatment with titanium dioxide or titanium phosphate and an organic resin. be. Modifications within the scope of this invention can be performed.

[Brief explanation of the drawing]

Figure 1 is a graphical diagram showing the effect of titanium dioxide and epoxy resin on the oxidative stability of red phosphorus, and Figure 2 is a graphical diagram showing the effect of titanium dioxide and epoxy resin on the oxidative stability of wet red phosphorus. 3 is a graph showing the effect of titanium dioxide, titanium phosphate and melamine-formaldehyde resin on the oxidative stability of red phosphorus,
FIG. 4 is a graph showing the effect of titanium dioxide and urea-formaldehyde resin on the oxidative stability of red phosphorus.

Claims (1)

[Claims] 1. In a red phosphorus-containing composition in which the red phosphorus particles have a particle size of at most 2 mm, titanium dioxide or titanium phosphate is expressed as the weight of titanium.
A red phosphorus-containing composition having red phosphorus particles having a particle size of at most 2 mm, characterized in that it contains 0.05 to 1.0% by weight and 0.1 to 5.0% by weight of an organic resin. 2. The composition according to claim 1, wherein the organic resin is an epoxy resin, a melamine-formaldehyde resin, or a urea-formaldehyde resin. 3. The composition according to claim 1 or 2, containing 0.5 to 3.0% by weight of an organic resin. 4 Add a titanium compound to an aqueous slurry of red phosphorus particles with a particle size of 2 mm at most; add an alkali to the slurry to adjust the pH of the slurry to 2 to 4, and add a titanium compound to the red phosphorus particles. Deposition of titanium dioxide or titanium phosphate in an amount of 0.05-1.0% by weight as Ti; adding a water-soluble or water-emulsifiable resin to the slurry and depositing the resin on the red phosphorus particles in an amount of 0.1-5.0% by weight. A method for preparing a red phosphorus-containing composition having a particle size of at most 2 mm, comprising separating red phosphorus particles from a slurry, which have been deposited and treated with a slurry. 5. The manufacturing method according to claim 4, wherein the organic resin is an epoxy resin, a melamine-formaldehyde resin, or a urea-formaldehyde resin. 6. The manufacturing method according to claim 4 or 5, wherein the resin added to the slurry is an uncured resin, and the resin deposited on the red phosphorus particles is a cured resin. 7. The manufacturing method according to any one of claims 4 to 6, wherein the titanium compound is titanium sulfate. 8. The production method according to any one of claims 4 to 6, wherein the titanium compound is titanium sulfate, and orthophosphoric acid or a water-soluble salt of orthophosphoric acid is added to the slurry. 9 Add the uncured epoxy resin and the curing agent for the resin to the slurry, adjust the pH of the slurry to 4 to 6, adjust the temperature of the slurry to 40 to 80°C, stir the slurry for 0.5 to 2 hours, and add the slurry to the slurry. pH of 7-8
7. A process according to any one of claims 4 to 6, wherein the deposition of the cured resin is carried out by raising the value to a value of . 10 Add uncured melamine-formaldehyde resin or uncured urea-formaldehyde resin to the slurry, adjust the pH of the slurry to a value of 2.5-4, adjust the temperature of the slurry to 80-100 °C, and adjust the pH of the slurry to a value of 0.5-2. 9. A method according to any one of claims 4 to 8, characterized in that the hardened resin is deposited by stirring for a period of time. 11. The manufacturing method according to any one of claims 4 to 10, wherein the slurry is heated to a temperature of 60 to 90°C, and then the titanium compound is added. 12 Wash the separated red phosphorus particles and heat at 100 to 130℃.
The manufacturing method according to any one of claims 4 to 11, wherein the drying method is performed at a temperature of .