JPS6224015B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a particulate flame retardant for producing a flame-retardant molded article, for example, by mixing it into resin pellets during molding of a flammable thermoplastic resin. Generally, in order to obtain flame-retardant thermoplastic resin molded articles, it is convenient to add a flame retardant to resin pellets, mix the flame retardant with a molten resin in a molding machine, and then mold the pellets. In this case, if the flame retardant is used in powder form, dust will be generated, which is bad for the working environment. If a powder or liquid flame retardant that does not flow well is used, automatic continuous metering will be inefficient and prone to metering errors. In addition, if it is in powder form, it is likely to be classified due to differences in shape during the process of mixing with resin pellets, or it will not spread well, resulting in non-uniform mixing. In addition, bridging occurs in the supply hopper due to the heat of mixing, making continuous molding of the resin difficult, and uneven mixing is likely to occur because the screws are inserted into the screws of the molding machine differently. Therefore, attempts have been made to create a masterbatch containing 30% flame retardant by weight of flame retardant and resin and mix this into resin pellets, or to add flame retardant as granules of appropriate size, but conventional methods In the granulation method, the flame retardant itself is granulated using a tableting method, roller compression method, spray granulation method, rotary granulation method, etc., so the required particle size may not be obtained or the particle size may become uneven, causing problems with flow. There were disadvantages such as: the strength was insufficient and it collapsed during transportation and mixing; the flame retardant decomposed due to long-term kneading at high temperatures; and a large amount of the above masterbatch had to be added to increase the flame retardant effect. . In order to overcome these drawbacks, the present invention is made by kneading a flame retardant with a solution containing a small amount of thermoplastic resin and granulating it, so that it has excellent fluidity and a predetermined relatively uniform particle size, making it easy to transport and To provide a method for producing a granular flame retardant that is difficult to disintegrate during a mixing process, can be uniformly dispersed in a resin by mixing it with resin pellets and applying it to a molding machine, and can be diluted with a large amount of resin pellets. According to the present invention, a bromine-containing aromatic or alicyclic halogen flame retardant compound or a mixture thereof for addition to a flammable thermoplastic synthetic resin, and a solution of a thermoplastic synthetic resin dissolved in an organic solvent as a binder are added to the flammable thermoplastic synthetic resin. A granular flame retardant for addition to flammable thermoplastic synthetic resin molded products, characterized in that the flame retardant compound is kneaded in a ratio of 70 to 99.5 to the thermoplastic synthetic resin for the binder, granulated, and dried. A manufacturing method is provided. The term "flame retardant" as used herein means a compound that is liquid or solid at room temperature and that can be added to a flammable substance to make it flame retardant. These flame retardants themselves are known, and examples thereof include bromine-containing compounds; specific examples include tetrabrom diphenyl ether, hexabrom diphenyl ether, decabrom diphenyl ether,
Tris(dichloropropyl) phosphate, tris(dibromopropyl) phosphate, tetrabromobutane, hexabromocyclododecane, monochloropentabromocyclohexane, tribromphenyl allyl ether, tribromphenyl metaallyl ether, 2,2-bis (4-Acroxy-3,5-dibromphenyl)propane, 2.
2-bis(4-methallyloxy-3,5-dibromophenyl)propane, 2,2-bis(4-dibromopropoxy-3,5-dibromophenyl)propane, 2,2-bis(4-dibromoisotyroxy-3)・5-Dibromphenyl)propane, mixtures thereof, etc. Among them, one pair by weight of a flame retardant with a melting point of 150℃ or higher and a flame retardant with a melting point of 150℃ or lower.
A mixture of hexabromocyclododecane and 2,2-bis(4-allyloxy-3,5-dibromophenyl) at a ratio of 0.1 to 1:1 is best.
Most preferred is a mixture with propane and/or tribromophenyl allyl ether in the above proportions. This is because these materials generate heat in the granulator and solidify. Examples of thermoplastic resins include polystyrene resin, polymethyl methacrylate resin, styrene-butadiene copolymer resin, styrene-maleic anhydride copolymer resin, polyester resin, polyamide resin, polyethylene resin, ethylene-vinyl acetate resin, and chlorine. Various resins such as polyethylene resin, polyvinyl chloride resin, and polycarbonate resin are used. In particular, in order to obtain a granular flame retardant that is easily soluble in solvents, easy to dry, strong, non-hygroscopic, and easily disintegrated in a molding machine,
Polymers or copolymers of monomers selected from the group consisting of styrene, butadiene, acrylic acid and derivatives thereof are preferred. The solvent may be any solvent as long as it dissolves the thermoplastic resin, and those containing chlorine, which has a relatively low boiling point, are easy to dissolve and provide a strong product, which is preferable from the standpoint of disaster prevention and drying. Examples include methylene chloride, chloroform, trichloroethylene, carbon tetrachloride, benzene, toluene, xylene, methyl ethyl ketone, and mixtures thereof. The concentration of the solution is preferably as high as possible in terms of resource saving and working environment, as long as the flame retardant can be uniformly kneaded and granulated. Kneading is carried out by mixing a solution of a thermoplastic resin in a solvent and a flame retardant in a ratio of 30 to 0.5 of the thermoplastic resin to 70 to 99.5 of the flame retardant, especially 10 to 0.5 of the thermoplastic resin to 90 to 99.5 of the flame retardant. is preferred. If it deviates from this range, the desired effect of the present invention cannot be obtained. As a granulation method, any known method can be used as long as it is possible to form a mass made by kneading flame retardant with a resin solution into a fixed particle size, but among them, a method using an extruder is used to form strong granules with uniform particle size. It is preferable because the product can be obtained with good productivity. For example, an extrusion molding method in which granules of a predetermined particle size are obtained by extruding from a die using a twin-screw extruder is preferred. The particle size of the granulated flame retardant depends on the purpose for which the granular flame retardant of the present invention is used and the size of the molding resin pellets to be added, but it is generally pellets with a diameter of 0.5 to 8 mm, particularly pellets with a diameter of 0.5 to 5 mm. The length is 1 to the diameter
Pellets with a density of 10 times are preferred because they are easy to dry, strong, and can be mixed uniformly with the resin. The granular flame retardant of the present invention may optionally contain a resin modifier,
For example, flame retardant aids such as antimony trioxide, titanium oxide, molybdenum oxide, zirconium silicate, zinc borate, stabilizers, colorants, weathering agents, ultraviolet absorbers, matting agents, antistatic agents, extenders, and other Compounding agents may be included. According to the present invention, it is not necessary to heat the heat retardant to a high temperature during the manufacturing process, so thermal decomposition of the heat retardant can be prevented, and granules of any particle size convenient for resin molding can be easily obtained. . In addition, since strong and uniform products can be easily obtained, weighing, transportation, etc. of granular products,
It does not disintegrate during the mixing process with resin,
Moreover, it can be uniformly dispersed in the resin during molding. Hereinafter, the present invention will be explained in more detail with reference to Examples. Parts and percentages are by weight. Examples 1 to 3 75 parts of flame retardant, 30% polymethyl methacrylate resin (Terpet 80N manufactured by Asahi Kasei) methylene chloride solution 10
Place the mixture in a high-speed mixer (manufactured by Fukae Kogyo) and mix for 2 minutes with an agitator at 400 rpm and a chopper at 300 rpm. The mixed compound is extruded using a twin-screw continuous extruder (manufactured by Fukae Kogyo, FSWG type 3B).
The material is poured into a hopper (mold) and continuously extruded at a speed of 90 kg/hour through a screen with 3 mm diameter openings.
A granular product with a diameter of 3 mm and a length of 7 to 10 mm was obtained. Next, in order to remove methylene chloride, this was dried in a fluidized fluid dryer, and the strength of the granular product was measured. As Comparative Example 1, a granular product was similarly obtained using 20 parts of water instead of the resin solution described above. Table 1 shows the strength of the granular products obtained in Examples and Comparative Examples.
Shown below.

【table】

[Table] Examples 4 to 6 Granular products were obtained in the same manner as in Examples 1 to 3 using 100 parts of a flame retardant and 20 parts of a 20% polystyrene solution in toluene. Table 2 shows the strength of the obtained granular products.

[Table] Example 7 2000 parts of polystyrene resin (Estyrene G-20 manufactured by Nippon Steel Chemical Industry Co., Ltd.) and 70 parts of a granular flame retardant were mixed for 10 minutes using a ribbon blender. Next, convert this to 3x6
Injection molding was performed at 230°C using a 15mm x 15mm mold. A total of 10 samples were taken, one every 10 shots, and a combustion test was conducted using the ASTM D-2863 method to check for variations in the oxygen concentration index (LOI value).
The results are shown in Table 3.

【table】

[Table] Examples 8 to 10 75 parts of flame retardant, 25 parts of antimony trioxide, 30% polymethyl methacrylate resin (Terpet, manufactured by Asahi Kasei)
Example 1 using 10 parts of 80N) methylene chloride solution
A granular product was obtained by the same operation as in 3. As Comparative Example 4, a granular product was similarly obtained using 20 parts of water instead of the resin solution described above. Table 4 shows the strength of the obtained granular product.

[Table] Examples 11 to 13 Granular products were obtained in the same manner as in Examples 1 to 3 using 100 parts of a flame retardant and 20 parts of a toluene solution of 20% polystyrene resin. Table 5 shows the strength of the obtained granular products.

[Table] Example 14 Polypropylene resin (J-115G manufactured by Ube Industries)
2000 parts and 70 parts of granular flame retardant in a ribbon blender.
Mixed for a minute. Next, this was injection molded at 230°C using a 3 x 6 x 15 mm mold. A total of 10 samples were taken, one every 10 shots, and the ASTM D-
A combustion test was conducted using the 2863 method, and variations in the oxygen concentration index (LOI value) were observed. The results are shown in Table 6.

【table】

Claims (1)

[Scope of Claims] 1. A bromine-containing aromatic or alicyclic halogen flame retardant compound or a mixture thereof for addition to a flammable thermoplastic synthetic resin, and a solution of a thermoplastic synthetic resin dissolved in an organic solvent as a binder, 70 to 99.5 of the flame retardant compound versus the thermoplastic synthetic resin for the binder
A method for producing a granular flame retardant for flammable thermoplastic synthetic resin molded articles, which comprises kneading at a ratio of 30 to 0.5, granulating, and drying. 2. The method according to claim 1, wherein the thermoplastic synthetic resin for the binder is a polymer or copolymer of monomers selected from the group consisting of styrene, butadiene, acrylic acid, and derivatives thereof. 3. The method according to claim 1 or 2, wherein the granulation is carried out using an extruder and the granular flame retardant is pellets with an average diameter of 0.5 to 8 mm.