JPH0437862B2 - - Google Patents

Description

[Detailed description of the invention]

<Technical field of the invention> The present invention relates to a red phosphorus flame retardant,
It is characterized by the use of red phosphorus with a limited shape, and is intended to improve the moisture resistance and corrosion resistance of flame retardants and resin compositions. <Background of the Invention> Red phosphorus flame retardants are useful for flame retardant thermosetting resins, especially epoxy resins, and are mainly used in insulating resin compositions for impregnation casting of high-voltage electronic components. Red phosphorus itself can be used as a flame retardant, but
Because red phosphorus is unstable to heat, friction, or shock, it is dangerous to store and handle it or to mix it with synthetic resins, and it also reacts with moisture in the air to generate toxic phosphine gas, making it difficult to handle the work. There are several problems with the direct use of red phosphorus, such as polluting the environment and poor compatibility with synthetic resins, which can cause work problems. It was an attempt to solve these problems by stabilizing it with various organic or inorganic substances. However, in recent years, with the miniaturization and higher voltage of electrical equipment, and the demand for higher performance electrical insulating materials, the requirements for the physical properties of red phosphorus flame retardants have also become stricter. The situation has become difficult to deal with. In other words, electronic components insulated with conventional resins containing red phosphorus flame retardants lack durability and reliability due to deterioration of the resin over time, resulting in poor insulation and corrosion of metal parts, resulting in decreased performance. It has been pointed out that this is mainly caused by the deterioration of the red phosphorus flame retardant, and there is a need for improvement. The deterioration of red phosphorus flame retardants is said to occur when red phosphorus reacts with trace amounts of moisture to produce phosphine and corrosive oxidation products. Red phosphorus is stabilized by coating phosphorus particles to block moisture, but stabilizing red phosphorus using this method has its own limits, and is used in high-quality materials with extremely strict requirements for moisture resistance and corrosion resistance. The current situation is that it cannot reach the level of performance of resins for electronic parts. For this reason, halogen-based flame retardants, which are said to have better moisture resistance and corrosion resistance than red phosphorus-based ones, or halogen-based flame retardants and antimony trioxide are used to make flame retardant impregnated casting resins for high-voltage electronic parts. However, halogen-based flame retardants not only have the fatal drawback of emitting toxic gas when burned, but also have a large effect on the electrical properties of the resin due to the large amount required. However, there are problems such as the high cost of the product and the high cost of the product. On the other hand, red phosphorus flame retardants do not cause any problems during combustion, and can achieve extremely high flame retardant effects with a small amount of addition, so they have almost no effect on the physical properties of the resin, and are also economically superior. There is a strong desire to improve the moisture resistance and corrosion resistance of red phosphorus flame retardants. In view of this situation regarding red phosphorus flame retardants, the inventors conducted intensive research into improving the moisture resistance and corrosion resistance of red phosphorus flame retardants. Recognizing that there are limits to this, we sought ways to solve the problem from a different angle. As a result, red phosphorus, which is obtained by a manufacturing method different from conventional ones and has a specific shape with particle surface conditions and physical properties completely different from conventional products, is extremely stable and can be used as a flame retardant in itself. However, by further surface-modifying the red phosphorus,
We have completed the present invention by discovering that the problems related to the moisture resistance and corrosion resistance of red phosphorus flame retardants can be completely solved. <Structure of the Invention> The present invention provides spherical red phosphorus, which is fine particles without crushed surfaces or aggregates thereof, which are directly obtained by a yellow phosphorus conversion treatment method that does not require a crushing process, and which is made into a thermosetting resin. and/or a red phosphorus flame retardant coated with aluminum hydroxide or zinc hydroxide, and a thermosetting resin composition containing the same. Red phosphorus is usually produced by heat-treating yellow phosphorus for several days in a reaction vessel called a conversion kettle. Obtained as a lump. In order for red phosphorus to exhibit flame-retardant effects in synthetic resins, it must be in a fine powder form, and therefore, for ordinary red phosphorus obtained as a lump from a conversion kettle, a pulverization process is not necessary. It is something that cannot be done. In contrast, the red phosphorus used in the present invention is obtained through a different conversion process and is directly obtained in the form of fine particles without going through a pulverization process, and is lighter, has a smaller bulk specific gravity, and is amorphous than conventional pulverized products. It is. Such light amorphous red phosphorus itself has high stability, but when it is further coated with thermosetting resin and/or aluminum hydroxide or zinc hydroxide, it is extremely stable and does not react well with water. Its properties are almost negligible compared to those coated with conventional crushed red phosphorus, and the moisture resistance and corrosion resistance of thermosetting resins containing this as a flame retardant are dramatically higher than conventional products. improve. The unique stability of the red phosphorus flame retardant obtained from such light amorphous red phosphorus is thought to be due to the fact that the surface condition of the raw material red phosphorus particles is completely different from that of conventional products. In other words, in the case of conventional red phosphorus, which is obtained by crushing solidly agglomerated lumps, the particle surface is composed of sharp ridges and fractured surfaces, forming a complex multi-ridged body. On the other hand, the spherical red phosphorus referred to in the present invention does not go through a crushing process, so it has almost no fractured surfaces or ridge lines, and is composed of fine particles and their aggregates that have spontaneous and continuous surfaces. Confirmed by microscopic observation. For this reason, crushed red phosphorus particles have many active sites on the crushed surface, easily adsorb moisture and oxygen, and actively react with these molecules, whereas spherical red phosphorus particles that do not go through the crushing process Phosphorus has almost no active sites and has an extremely stable surface, so it is thought that no moisture adsorption or reaction occurs. In addition, even when coating with thermosetting resin or aluminum hydroxide, etc., the coating of crushed red phosphorus tends to be uneven due to its surface condition and exposed crushed surfaces tend to remain.On the other hand, with spherical particles, the coating is uniform and complete. It is presumed that this makes a decisive difference in the moisture resistance stability of the coated red phosphorus. Because spherical red phosphorus has such an extremely stable surface, it can be used as a flame retardant without coating for applications with relatively mild requirements for moisture resistance and corrosion resistance. It shows no inferiority in performance to coated red phosphorus made from red phosphorus (see Table 1), but thermosetting is suitable for applications with strict requirements regarding moisture resistance and corrosion resistance, such as high-voltage electronic components. It is desirable to carry out a coating treatment with resin, aluminum hydroxide, etc., thereby almost eliminating the influence of the addition of red phosphorus flame retardants and providing almost perfect moisture resistance and corrosion resistance. Further, it is preferable to perform a coating treatment from the viewpoint of increasing compatibility with the resin and improving workability. The spherical red phosphorus used in the present invention can be produced, for example, by the following method. That is, in a closed container purged with inert gas, yellow phosphorus is heated to a temperature close to its boiling point to start the conversion reaction of red phosphorus, and when the generated red phosphorus nuclei grow to the desired particle size, the reaction is stopped. When the process is stopped and unconverted yellow phosphorus is distilled off, relatively light amorphous red phosphorus in the form of fine particles is obtained, which requires almost no pulverization. At this time, the conversion rate and the particle size of the red phosphorus particles can be adjusted by adjusting the reaction time and reaction temperature. The conditions for producing red phosphorus suitable for the purpose of the present invention include reaction temperature
Preferably, the temperature is 250°C to 350°C and the conversion rate is 60% or less. If the reaction temperature is below 250°C, it is not practical because the conversion rate is slow, and if it is above 350°C, it is difficult to control the conversion reaction, the properties of the product are not uniform, and the shape does not meet the purpose of the present invention. You won't be able to get it. Furthermore, if the conversion rate is increased to 60% or more, the produced red phosphorus will become agglomerated and cannot be used as a flame retardant without going through a pulverization process, making it impossible to achieve the object of the present invention. Generally, the longer the reaction time and the higher the reaction temperature, the higher the conversion rate and the larger the particle size. for example,
40% conversion rate and average particle size after 4 hours reaction at 280℃
50 μm particles are produced. In addition, the particle size of the red phosphorus obtained in this way has a very narrow distribution width and extremely high uniformity compared to ordinary pulverized products, and as a result, even if the average particle size is the same, the porosity is high. , a light product with relatively low bulk specific gravity can be obtained. As the conversion rate increases, more red phosphorus particles are produced as aggregates, but the aggregates have weak cohesiveness, are brittle and easily break down, and do not require treatment to the extent of pulverization. However, if the particle size needs to be adjusted depending on the application, disintegration by simple mechanical treatment poses no problem for the purpose of the present invention. In this case, the fracture surface that occurs as the aggregate collapses has little effect on the stability of red phosphorus. Although this is called a fractured surface, it is physically close to a spherical surface, and unlike a fractured surface formed by crushing a solid lump, the stability of the surface is not inferior to that of a spherical surface, so to speak. It can be called a face.
Therefore, in the present invention, substances having such a collapse surface are also referred to as spherical red phosphorus, and in the following description, these aggregates are also referred to as spherical red phosphorus. The red phosphorus for the flame retardant of the present invention preferably has an average particle diameter of several microns or more and 200 microns or less.
Spherical red phosphorus can also be produced by a gas phase conversion method in which yellow phosphorus vapor is heated in an inert gas, a molten salt method, and the like. In the present invention, the spherical red phosphorus is coated with aluminum hydroxide or zinc hydroxide by water-soluble salts of aluminum or zinc,
For example, an aqueous solution of aluminum sulfate, aluminum chloride, zinc sulfate, zinc chloride, etc. is added to an aqueous suspension of red phosphorus, and then aluminum hydroxide or zinc hydroxide is prepared by neutralization with sodium hydroxide or metathesis with ammonium bicarbonate. This is done by adsorbing it onto red phosphorus particles. At this time, the aqueous suspension of red phosphorus is 10 to 100 parts by weight of red phosphorus per 100 parts by weight of water, the concentration of the aqueous solution of water-soluble salts of aluminum or zinc is 5 to 30%, and the amount of hydroxide coating produced is red. The amount is preferably 1 to 30 parts by weight per 100 parts by weight of phosphorus, and an excellent red phosphorus flame retardant can be obtained, but the present invention is not particularly limited thereto. In the present invention, the thermosetting resin used for coating the spherical red phosphorus is a synthetic raw material of the resin or its initial condensation product that easily undergoes a polymerization reaction in an aqueous suspension of red phosphorus or its initial condensation. Any resin raw material can be used as long as it emulsifies and disperses in water and deposits and coats the red phosphorus particle surface uniformly, but usually phenol/formalin-based, urea/formalin-based, etc.
Selected from melamine/formalin type, furfuryl alcohol/formalin type, aniline/formalin type, polyhydric alcohol/polybasic acid type, etc.
Among the above resin groups, furfuryl alcohol/formalin series, aniline/formalin series, polyhydric alcohol/polybasic acid series, etc. are difficult to polymerize in the presence of a large amount of water, so initial condensation products of resin raw materials are used. It is preferable to prepare it in advance and add it to an aqueous suspension of red phosphorus. The resin coating treatment conditions vary somewhat depending on the type of thermosetting resin used, but the synthetic raw material for the resin is added to an aqueous suspension of red phosphorus containing 10 to 100 parts by weight of red phosphorus per 100 parts by weight of water. Or the initial condensate with red phosphorus
Add 1 to 35 parts by weight per 100 parts by weight, and when using resin synthetic raw materials, heat at 40 to 100°C for 1 to 3 hours.
60 to 100 when using a pre-prepared initial condensate
Stirring treatment is performed at ℃ for 1 to 2 hours. At this time, a polymerization catalyst and a filler such as aluminum hydroxide, magnesium hydroxide, or titanium hydroxide may be allowed to coexist, if necessary. Addition of a filler increases the mechanical strength of the resin coating and has the effect of hiding the purple-red color characteristic of red phosphorus, which can contribute to expanding the uses of red phosphorus flame retardants. The amount of filler added is preferably 1 to 35 parts by weight per 100 parts by weight of red phosphorus. When the product is separated, washed with water, and dried at 130 to 140°C to complete the polymerization reaction, a red phosphorus flame retardant with extremely good moisture and corrosion resistance is obtained. In addition, if aluminum hydroxide or zinc hydroxide is adsorbed on red phosphorus particles before coating with thermosetting resin, the moisture resistance and corrosion resistance of red phosphorus will further improve, and this can be used to make flame retardant. In such a resin composition, the addition of the red phosphorus flame retardant shows almost no effect over a long period of time. Pretreatment with aluminum hydroxide or zinc hydroxide is water 100%
Neutralization reaction of a water-soluble compound such as aluminum or zinc sulfate or chloride with caustic alkali in an aqueous suspension of red phosphorus containing 5 to 100 parts by weight of red phosphorus, or bicarbonate. This is carried out by producing aluminum hydroxide or zinc hydroxide through a metathesis reaction with ammonium, and adsorbing it onto red phosphorus particles. The aluminum salt or zinc salt added is preferably in an amount necessary to produce 0.1 to 30 parts by weight of hydroxide based on 100 parts by weight of red phosphorus. As shown in Table 2, the red phosphorus flame retardant of the present invention is
It has extremely high moisture resistance and stability, and there is almost no generation of phosphine or corrosive acid substances, which are thought to be caused by the adsorption of water molecules. Therefore, it is optimal as a flame retardant for thermosetting resins for high-voltage electronic components, which require a high degree of quality stability, and an extremely stable resin composition can be obtained.
The resin composition contains, for example, 100 parts by weight of epoxy resin, 5 to 40 parts by weight of a red phosphorus flame retardant, and 5 to 150 parts by weight of aluminum hydroxide as a filler and flame retardant auxiliary agent.
parts by weight, 20 to 90 parts by weight of an acid anhydride curing agent, and a curing accelerator. Epoxy resin refers to any aromatic, alicyclic, or aliphatic epoxide having one or more epoxy groups in the molecule, but it is especially suitable for use in impregnation and casting of electronic parts, as it is liquid at room temperature. preferable. For example, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and polyglycidyl esters of polycarboxylic acids such as phthalic acid and terephthalic acid are suitable. If aluminum hydroxide is added in a large amount, the viscosity of the resin liquid will increase, which will interfere with the casting impregnation work, and if it is too small, the flame retardant effect will be insufficient, so epoxy resin
It is preferably 5 to 150 parts by weight per 100 parts by weight. The amount of red phosphorus flame retardant added is 5 to 40 per 100 parts by weight of resin, taking into account the flame retardant effect and the effect on resin viscosity.
Preferably, it is expressed in parts by weight. Acid anhydrides are most suitable as the curing agent, and a wide variety of known ones such as phthalic anhydride, tetrahydrophthalic anhydride, and succinic anhydride can be used.
Further, as the curing accelerator, imidazole derivatives such as 2-phenylimidazole and 2-ethyl-4-methylimidazole are preferred from the viewpoint of workability and the like. The epoxy resin composition containing the red phosphorus flame retardant of the present invention was thoroughly kneaded and heated at 60°C for 4 hours.
The flame retardancy, color fastness and electrical properties of the resin cured at 105℃ for 7 hours were measured and compared with the measured values of an epoxy resin composition containing a red phosphorus flame retardant made from conventional red phosphorus. did. Table 3 shows examples and comparative examples of resin compositions, and Table 4 shows measured values of cured resin obtained from each resin composition. Regarding all of the measurement items, the product containing the red phosphorus flame retardant based on spherical red phosphorus according to the present invention is far superior to the conventional product, and the effect of adding the flame retardant is
It is clear that the amount is extremely small, and this has a remarkable effect on improving the durability and reliability of high-voltage electronic components. Example of Production of Spherical Red Phosphorus A stainless steel reaction vessel (capacity 1) equipped with a thermocouple, a reflux condenser (air-cooled), and a gas exhaust pipe was used as a reaction device. The top of the reflux condenser was connected to the nitrogen gas cylinder via a switch, and a switch was also provided between the gas discharge pipe and the reaction vessel. Attach a water cooling jacket to the gas exhaust pipe,
The tip was led into water in a yellow phosphorus collection container. water
500 g of yellow phosphorus was loaded into a 100 ml reaction vessel, the two pots were opened, nitrogen gas was introduced, the inside of the apparatus was replaced with gas, and then heated using an electric heater installed at the bottom of the reaction vessel. When the water covering the yellow phosphorus finishes evaporating, the temperature begins to rise, and when it reaches 140℃, the inside of the device is sealed by closing the two pots together.
Subsequently, heating was performed to raise the temperature to 270°C. After refluxing the generated yellow phosphorus vapor and reacting at the same temperature for 4 hours, the outlet of the discharge pipe was opened, and the reflux condenser was also opened and nitrogen gas was introduced while the boiling point of yellow phosphorus (280℃ ), unconverted yellow phosphorus was distilled, passed through a discharge pipe, and coagulated in a yellow phosphorus collection vessel. After about 2 hours of distillation, most of the yellow phosphorus was distilled out, but in order to remove a trace amount of residual yellow phosphorus, the mixture was heated at 330°C for an additional hour. Average particle size from reaction vessel
211 g of fluid sphere-like red phosphorus with a diameter of 50 μm was obtained. <Example> Example 1 Suspend 500 g of spherical red phosphorus in 800 ml of water, add 300 ml of 10% aluminum sulfate aqueous solution, dropwise add 100 ml of 5% sodium hydroxide aqueous solution with thorough stirring, and heat to 50°C. Hold for 30 minutes. This was filtered, washed with water, and dried at 120°C to obtain 516 g of coated red phosphorus. Example 2 Suspend 500 g of spherical red phosphorus in 800 ml of water, add 200 ml of 20% aluminum chloride aqueous solution, dropwise add 400 ml of 20% ammonium bicarbonate aqueous solution with thorough stirring, heat to 50°C and age for 30 minutes. . After cooling, it was filtered, washed with water, and dried at 120°C to obtain 536 g of coated red phosphorus. Example 3 Suspend 500 g of spherical red phosphorus in 800 g of water, add 300 ml of 20% zinc chloride aqueous solution, and stir thoroughly.
Drop 400ml of 10% sodium hydroxide aqueous solution,
Heat to ℃ and mature for 30 minutes. After cooling, it was filtered, washed with water, and dried at 120°C to obtain 540 g of coated red phosphorus. Example 4 Suspend 500 g of spherical red phosphorus in 1000 ml of water, add 15 g of phenol and 27 g of 37% formalin, and heat at 80°C.
Heat to and add 10 g of 85% phosphoric acid while stirring. 1
After heating and stirring at the same temperature for a period of time, the mixture is allowed to cool, filtered, and washed with water. Dry the strainer at 140℃ for 3 hours and coat with red phosphorus.
Obtained 523g. Example 5 500 g of spherical red phosphorus was suspended in 750 ml of water, and urea
Add 10g of 37% formalin and heat to 90°C with stirring, and then add 10g of 85% phosphoric acid. After continuing to heat and stir for 2 hours, let stand overnight, filter,
Wash with water. Dry at 140℃ for 3 hours, coated red phosphorus 514
I got g. Example 6 A viscous initial condensate obtained by reacting a mixture of 27 g of furfuryl alcohol, 3 ml of water, and 0.5 g of 85% phosphoric acid on a boiling water bath for 5 hours, 10 g of 37% formalin, and 500 g of spherical red phosphorus. and 800 ml of water under vigorous stirring and heated to 90°C. After heating and stirring for 1 hour, the mixture was filtered, washed with water, and dried at 130°C for 3 hours to obtain 525 g of coated red phosphorus. Example 7 500 g of spherical red phosphorus, 50 g of magnesium hydroxide
and 6 g of melamine in a suspension of 750 ml of water, 37
% formalin and 10 g of sodium carbonate, and stirred and reacted at 90°C for 2 hours. After cooling for a day and night, it was filtered, washed with water, and dried at 135°C for 3 hours to obtain 555 g of coated red phosphorus. Example 8 4.3g of 98% glycerin, 2.5g of phthalic anhydride and 15g of linseed oil fatty acid were mixed and heated to 200-230°C while passing carbon dioxide gas, then 3.3g of phthalic anhydride was added and the temperature was raised to 245°C. When the acid value reaches 12 to 15, cool it, add 2 ml of emulsifying dispersant Emanone #4110 manufactured by Kao Atlast, and disperse it in 100 ml of water. Add this emulsified dispersion to 750ml of water and 500g of spherical red phosphorus.
and 50 g of aluminum hydroxide, and heated and stirred at 90° C. for 1 hour. After cooling, filter, wash with water, and dry at 140℃ for 4 hours to obtain coated red phosphorus 573.
I got g. Example 9 250g of spherical red phosphorus was suspended in 500ml of water, 8%
Add 40 ml of aluminum sulfate aqueous solution and stir thoroughly. 18 ml of 5% sodium hydroxide solution was added dropwise to this, and the mixture was heated to 50°C and held for 10 minutes. Next, 8 g of phenol and 15 g of 37% formalin were added, and the mixture was heated at 80°C.
After heating and stirring for 1 hour, the mixture was allowed to cool, filtered, washed with water, and dried at 140°C for 3 hours. 270 g of coated red phosphorus was obtained. Example 10 40 ml of 8% aluminum sulfate aqueous solution was added to a suspension consisting of 250 spherical red phosphorus and 500 ml of water, and after stirring, 45 ml of 15% ammonium bicarbonate aqueous solution was added dropwise.
Matured at 50°C for 20 minutes. PH 10.0 with ammonia water
100 g of 12.5% lysol type phenolic resin prepolymer (phenol/formalin = 1/2 mol) prepared in advance and 25 g of ammonium chloride were added and stirred at 50° C. for 30 minutes. After cooling, filter and
Washed with water and dried at 120℃ for 1 hour, coated red phosphorus 264g
I got it. Example 11 80 ml of an 8% zinc sulfate aqueous solution was added to a suspension consisting of 500 g of spherical red phosphorus and 900 ml of water, and after stirring,
Add 100ml of ammonium bicarbonate aqueous solution dropwise to 60°C.
Heat for 20 minutes. To this was added a reaction mixture of acentone-formalin initial condensate prepared from 26 g of acetone and 42 g of 37% formalin, and the mixture was heated at 65°C with stirring.
Heat for 30 minutes. After cooling, it was filtered, washed with water, and dried at 130°C for 1 hour to obtain 572 g of coated red phosphorus. Example 12 A suspension consisting of 500 g of spherical red phosphorus and 750 ml of water
After adding 65 ml of 10% aluminum sulfate aqueous solution and stirring, 100 ml of 15% ammonium bicarbonate aqueous solution was added dropwise and heated at 60°C for 20 minutes. Then titanium hydroxide 30
a suspension consisting of g and 30 ml of water, and 6 g of melamine,
Add 28g of 37% formalin and adjust the pH with ammonia water.
Adjust the temperature to 7.5 and continue stirring at 90°C for 2 hours. Leave to cool overnight, filter and wash with water, dry at 135℃ for 3 hours,
518 g of coated red phosphorus was obtained.

[Table] Stabilized crushed red phosphorus (1) Pulverized red phosphorus treated in the same manner as in Example 4 Stabilized crushed red phosphorus (2) Pulverized red phosphorus treated in the same manner as in Example 9 Measurement method Bulk specific gravity Ratio Volume tester (manufactured by Ishiyama Scientific Instruments Manufacturing Co., Ltd.)
Take 10 g of sample in a 500 ml flask and shake it 100 times to measure the amount of phosphine generated. Suspend 20 g of the sample in 40 ml of water in a 500 ml flask, shake thoroughly, seal, and leave for 24 hours. Measure the phosphine concentration in the sample.Ignition temperature: Place 1g of the sample in a porcelain crucible with a capacity of 10ml, leave it in an electric furnace, heat it at a temperature increase rate of 1℃/min, and measure the ignition temperature.Elution P ₂ O ₅ sample Suspend 5g in 100ml of water and heat at 121℃.
After being left at 2.2 atm for 100 hours, it was filtered and the P ₂ O ₅ content in the filtrate was measured.

【table】

[Table] All measurement methods are in accordance with Table 1 Comparative Example 1 Pulverized red phosphorus treated in the same manner as in Example 1 〃 2 Pulverized red phosphorus treated in the same manner as in Example 4 〃 3 Pulverized red phosphorus was carried out Processed in the same manner as in Example 5 〃 4 Pulverized red phosphorus was treated in the same manner as in Example 9 〃 5 Pulverized red phosphorus was treated in the same manner as in Example 10 〃 6 Pulverized red phosphorus was treated in the same manner as in Example 11 processed

【table】 The numbers in parentheses are the example numbers. Numbers represent parts by weight. The red phosphorus in the comparative example is as follows: 1 Untreated spherical red phosphorus 2. Pulverized red phosphorus treated in the same manner as in Example 1. 3 Pulverized red phosphorus treated in the same manner as in Example 4 4 Pulverized red phosphorus treated in the same manner as in Example 6 5 Pulverized red phosphorus treated in the same manner as in Example 10

[Table] Measurement method Flame retardancy JISK-6911 Flame resistance test B method Moisture resistance (water absorption rate) Conforms to JISK-6911 boiling water absorption test. However, the measurement conditions are 121℃, 2 atmospheres, 100% RH, and 100 hours. Corrosion A certain amount of resin composition is applied to a copper plate with a certain surface area, cured, and left in an air bath at 140°C and 80% RH for 200 hours, after which the resin layer is peeled off. Place a 1 mm square piece of transparent graph paper on the peeled surface and count the number of discolorations within 1 cm ² (1 mm ² × 100 pieces). Dielectric constant and dielectric loss tangent According to JISK-6911 dielectric constant and dielectric loss tangent measurement method.

Claims (1)

[Scope of Claims] 1. Red phosphorus that is spherical-like red phosphorus without a crushed surface and/or an aggregate thereof obtained directly by a yellow phosphorus conversion treatment method that does not require crushing. Phosphorous flame retardant. 2 Spherical red phosphorus and/or aggregate thereof, which is obtained by heating yellow phosphorus to 250 to 350°C in a reaction vessel in which the red phosphorus is replaced with an inert gas and converting it at a conversion rate of 60% or less. Claim 1 which is phosphorus
Red phosphorus flame retardant as described in section. 3. The red phosphorus flame retardant according to claim 1, wherein the spherical red phosphorus and/or the red phosphorus aggregate thereof is coated with a thermosetting resin. 4. The red phosphorus flame retardant according to claim 1, wherein the spherical red phosphorus and/or the red phosphorus aggregate is coated with aluminum hydroxide or zinc hydroxide. 5. Claim 1, in which spherical red phosphorus and/or red phosphorus that is an aggregate thereof is coated with aluminum hydroxide and/or zinc hydroxide, and is further double coated with a thermosetting resin. Red phosphorus flame retardant listed. 6. The red according to claim 3 or 5, wherein the thermosetting resin coating is carried out in the presence of one or two compounds selected from aluminum hydroxide, magnesium hydroxide, and titanium hydroxide. Phosphorous flame retardant.