JP3053932B2 - Granulation method of tetrabromobisphenol flame retardant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for granulating a tetrabromobisphenol (hereinafter abbreviated as "TBBP") flame retardant, and more particularly, from a powdery TBBP flame retardant to form retention, handling and flow. The present invention relates to a method for producing TBBP-based flame retardant granules having excellent properties, large bulk density and high drying efficiency with good yield.

[0002]

2. Description of the Related Art A TBBP-based flame retardant obtained by reacting a carbonate precursor with TBBP and a terminal terminator is particularly preferably used in the range of 0.01 to 0.10. Since such a flame retardant has a low molecular weight, it has low mechanical strength, can be obtained only as fine powder, and has extremely poor handleability. Also, during transportation and drying,
It is further miniaturized and easily adheres to the machine wall electrostatically. In particular, in the case of drying, fine powder adhering to the wall of the machine causes deterioration in quality, so that the powder must be dried at a low temperature of 130 ° C. or less, and there are problems such as insufficient solvent removal.

[0003] As a method of solving the powder handling property, generally, a method of blending a powder with a binder, compressing the powder, and then crushing the powder into granules has been used. Most of the flame retardants are used by mixing with plastics.However, when a flame retardant containing a binder is used for plastics, most of the plastics cause a decrease in flame retardancy, burning during molding, and a decrease in physical properties. At present, no satisfactory binder has been found. There is a strong demand for a granular flame retardant that has good handleability, has high flame retardancy of a molded product obtained when used, and does not degrade the quality.

[0004]

SUMMARY OF THE INVENTION The present invention provides a TB having excellent shape retention, handleability and fluidity, a large bulk density and a high drying efficiency.
An object of the present invention is to provide a compression molding granulation method for producing BP-based flame retardants at a low compression pressure with good yield.

The present inventors have conducted intensive studies to achieve the above object. As a result, when a powder of a TBBP-based flame retardant is compression-molded and granulated, a specific amount of an organic solvent is added to the powder of the TBBP-based flame retardant in advance. , The organic solvent acts as a binder, has sufficient shape-retaining strength even when the molding pressure is reduced, and has a very good drying efficiency and granulation with good yield despite the large particle size. And completed the present invention.

[0006]

SUMMARY OF THE INVENTION The present invention provides a polycarbonate
Its powdery TBBP flame retardant containing an organic solvent 0.2 to 25% by weight is a good solvent or poor solvent for the chromatography preparative
This is a method for granulating a TBBP-based flame retardant, which comprises compression molding at a temperature lower than the melting point of the flame retardant and then drying.

The TBBP-based flame retardant referred to in the present invention is produced by reacting a carbonate precursor with TBBP and a terminal stopper.
If necessary, another dihydric phenol may be copolymerized. TBBP used here is the following general formula

[0008]

Embedded image

Wherein R represents 1 carbon atom
15 divalent aliphatic group, alicyclic group, phenyl substituted aliphatic group, -O -, - S -, - SO -, - SO 2 - or -C
O-. As the bromo-substituted dihydric phenol, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane is preferably used.
5-dibromo-4-hydroxyphenyl) methane, bis (3,5-dibromo-4-hydroxyphenyl) sulfone, bis (3,5-dibromo-4-hydroxyphenyl) ether and the like, which may be used alone or Two or more kinds may be used in combination. Examples of the carbonate precursor include carbonyl halide, carbonate, and haloformate, and specifically, phosgene, diphenyl carbonate,
The dihaloformates of TBBP and the like can be mentioned. As the terminal terminator, a monovalent phenol compound such as tribromophenol, p-tert-butylphenol, or phenol is preferably used. Further, for example, a branched TBBP-based flame retardant obtained by reacting a polyfunctional aromatic compound having three or more functions with TBBP, a terminal terminator and a carbonate precursor may be used, and for example, 2,2-bis (4-hydroxy Phenyl)
A dihydric phenol such as propane [commonly known as bisphenol A] may be copolymerized. Further, the flame retardant of the present invention
It may be a mixture of two or more TBBP-based flame retardants. Such a TBBP-based flame retardant has a temperature of 20 ° C. and a concentration of 3.0 g / dl.
Specific viscosity (η _sp ) measured with methylene chloride solution is 0.01
~ 0.10 is preferred.

The powdery TBBP-based flame retardant used in the present invention comprises:
Although it may be produced by any method, TBBP and phosgene are reacted with an alkaline aqueous solution of a terminal stopper in the presence of an organic solvent, and an excess of an organic solvent solution is obtained from an organic solvent solution of the obtained reaction product. , And a powder of a reaction product containing a predetermined amount of an organic solvent is preferably used. Of course, an organic solvent may be added to the dry powdery TBBP-based flame retardant to contain a predetermined amount of the organic solvent.

The organic solvent to be contained in the powdery TBBP-based flame retardant is "Polycarbonate" by WFCHRISTOPHER, DWFOX. (Poor SolventS), “Very Solvent”
Solvent corresponding to "Poor Solvents" and "Weak precipitants" (hereinafter referred to as "poor solvent"), and a mixture of a good solvent and 1% by weight or more of a poor solvent and / or a solvent corresponding to "Nonsolvents" (hereinafter referred to as "non-solvent") Examples of such an organic solvent include ethane tetrachloride, 1,1,2-trichloroethane, 1,2-dichloroethane, methylene chloride, and the like.
1,2-dichloroethylene, chloroform, dioxane,
Examples thereof include a good solvent such as tetrahydrofuran, a poor solvent such as cyclohexanone, benzene, toluene and acetone, and a mixture of a good solvent with 1% by weight or more of a poor solvent and / or a non-solvent such as hexane and heptane.

The content of the organic solvent is 0.2 to 25% by weight based on the total amount of the TBBP-based flame retardant and the organic solvent. When the content of the organic solvent is less than 0.2% by weight, the effect as a binder at the time of compression molding is not sufficient, and a high compressive force is required in order to maintain shape retention, thereby achieving the object of the present invention. I can't get it. On the other hand, if the content is more than 25% by weight, large lumps are formed in the storage tank and the feeder, which may cause troubles or require equipment having a large drying capacity, which is not suitable. In particular, when a mixed solvent obtained by mixing a good solvent with 1% by weight or more of a poor solvent and / or a non-solvent or a poor solvent is used as an organic solvent, the efficiency of the dechlorinated solvent at the time of drying the obtained granules is remarkably improved. be able to.

For the compression molding performed in the present invention, for example, a briquetting machine, a compacting machine, a gear extrusion granulator, a ring die granulator, a tablet machine and the like are used. The temperature during compression molding may be lower than the melting point of the flame retardant. Further, in the compression molding, instead of directly forming into a granule, for example, it may be formed into a sheet by compression molding and then crushed by a crusher.

For drying performed after granulation, an optional dryer is used, and examples thereof include a fluidized dryer, a paddle dryer, and a circulating hot air dryer. The drying temperature is preferably 130 to 145 [deg.] C. because the particle size is coarse and there is almost no adhesion to the machine wall, and the drying efficiency can be significantly improved.

[0015]

The present invention will be further described with reference to the following examples. The determination of methylene chloride, n-heptane and acetone was determined by gas chromatography [Hitachi Ltd. 2
63 type] using Dioctyl Sebacate as a column filler at 85 ° C. by the headspace method.

[0016]

Example 1 A polycarbonate oligomer type of TBA obtained by a solution method using bis (3,5-dibromo-4-hydroxyphenyl) propane (hereinafter referred to as TBA) and phosgene as raw materials and tribromophenol as a terminal stopper. A methylene chloride solution containing a flame retardant (hereinafter referred to as a TBA-based flame retardant) was purified with water to obtain 200 kg of a 15% by weight methylene chloride solution of a TBA-based flame retardant having a specific viscosity of 0.075.

The methylene chloride solution was placed in a 200-liter mixing tank equipped with a stirrer previously charged with 100 liters of hot water at 45 ° C. at a rate of maintaining the internal temperature at 45 ° C. at a rate of 3 kg / cm.
^The steam was supplied together with the ^two steams, and the supply of steam was stopped when the methylene chloride was evaporated to obtain a water slurry of the powder of the TBA-based flame retardant. Add 3 kg of n-heptane, stir and mix to mix TB
After impregnating the powder of the A-based flame retardant, it was supplied to a centrifugal separator and dehydrated to obtain the powder of the TBA-based flame retardant. The obtained powder had a methylene chloride content of 15% by weight and an n-heptane content of 5.3% by weight.

This powder is compressed at a normal temperature with a compacting machine at a compression pressure of 200 kg / cm ² to form a plate having a thickness of 2 mm, crushed with a hammer crusher, and heated at 140 ° C. with an explosion-proof hot air dryer at 140 ° C. Dried for 30 hours, methylene chloride content 30 ppm, n-heptane content 100 ppm,
Particle size distribution was 8 to 30 mesh 88% by weight, less than 30 mesh 12% by weight, and the amount of fine powder was small, the particle diameter was uniform, the handling was easy, and the granules of the TBA-based flame retardant with a low content of methylene chloride were obtained.

[0019]

Example 2 Methylene chloride content 1500 ppm, specific viscosity 0.030, particle size distribution less than 48 mesh 99.9% by weight
TBA series flame retardant [manufactured by Teijin Chemicals Ltd., trade name: FG850]
0], 10% by weight of acetone was added to the powder and mixed.
Compression granulation was carried out in the same manner as in Example 1, and the mixture was dried at 135 ° C. for 6 hours using an explosion-proof hot-air drier to obtain a methylene chloride content of 75.
ppm, acetone content 85ppm, particle size distribution 8 to 30 mesh 85% by weight, less than 30 mesh 15% by weight, fine powder, small particle size, easy to handle with uniform particle size and low methylene chloride content Obtained.

[0020]

Comparative Example 1 The same TBA-based flame retardant powder as used in Example 2 was used as in Example 2 without adding acetone.
When compression granulation was carried out in the same manner as in Example 2, a plate-like body having a strength was not obtained, and was not practical.

A high pressure of 1000 kg / cm ² was required to obtain a crushable plate by a hammer crusher. Example 2 A plate obtained at a high pressure of 1000 kg / cm ^{2 was} prepared.
Crushed in the same manner as in
After drying for 1 hour, methylene chloride content is 1250 ppm, particle size distribution is 8 to 30 mesh 40% by weight, less than 30 mesh 60
By weight, granules were obtained. These granules were not only difficult to handle due to a large amount of fine powder, but also had a high content of methylene chloride.

[0022]

According to the present invention, TBBP-based flame retardants having excellent shape retention, handleability, fluidity, large bulk density and high drying efficiency can be produced with good yield by compression molding at a low pressure. This makes it possible to achieve a special effect.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C09K 21/08 C08G 64/10 C08J 3/12 C08K 5/13

Claims (1)

(57) [Claims] 1. A good solvent or a good solvent for polycarbonate.
Its flame retardant tetrabromobisphenol flame retardant powder containing 0.2 to 25 wt% of an organic solvent which is a poor solvent
A granulation method of a tetrabromobisphenol-based flame retardant, which is carried out by compression molding at a temperature lower than the melting point of the agent and then drying.