JPH0428740B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a granular flame retardant for producing flame-retardant molded articles by mixing it into resin pellets during molding of a flammable thermoplastic resin. Generally, in order to obtain a flame-retardant thermoplastic resin molded article, it is convenient to add flame retardant to resin pellets, mix the flame retardant with a molten resin in a molding machine, and mold the mixture. 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 disadvantages, the present invention has excellent fluidity, a predetermined relatively uniform particle size, and is difficult to disintegrate during transportation and mixing processes, but when mixed with resin pellets and put into a molding machine, it can be mixed into resin pellets. To provide a granular flame retardant that can be uniformly dispersed and diluted with a large amount of resin pellets. According to the present invention, a granular flame retardant containing 70% by weight or more of a flame retardant and 30% by weight or less of a thermoplastic resin is provided. The flame retardant referred to here means a bromine-containing aromatic or alicyclic halogen flame retardant compound that is liquid or solid at room temperature and can be added to a flammable substance to make it flame retardant. . These flame retardants themselves are publicly known, and examples include compounds containing halogen bromine; specific examples include:
Tetrabrom diphenyl ether, hexabrom diphenyl ether, decabrom diphenyl ether, hexabrom cyclododecane, monochloropentabrom cyclohexane, tribrom phenyl allyl ether, tri brom phenyl metaallyl ether, 2,2-bis(4 -Allyloxy-
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-dibromoisobutyroxy-3, Dimeric and trimeric halides of 5-dibromophenyl)propane, butadiene or isoprene or chloroprene, mixtures thereof, and the like. In particular, a flame retardant with a melting point of 150℃ or higher and a flame retardant with a melting point of 150℃ or lower at a ratio of 1:0.1 to 1:1 by weight.
For example, a mixture of hexabromocyclododecane and 2,2-bis(4-allyloxy-3,5-dibromphenyl)propane and/or tribromphenyl allyl ether in the above ratio is preferable. Most preferred. 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. Next, the ratio of the flame retardant to be granulated and the thermoplastic resin is such that the flame retardant is 70 to 99.5% by weight or more and the thermoplastic resin is 30 to 0.5% by weight or less in the resulting granular flame retardant. be. If it deviates from this range, the desired effect of the present invention cannot be obtained. Flame retardant 70~99.5% by weight or more and thermoplastic resin 30~
There are several methods for granulating a composition containing 0.5% by weight or less into granules of a predetermined size. For example, (a) a method in which a flame retardant is kneaded with a solution of a thermoplastic resin and granulated; (b) a method in which the composition is compressed to form a sheet-like mass and then cut or crushed. First, a method will be described in which a flame retardant is kneaded with a thermoplastic resin solution, the kneaded mass is granulated, and the solvent is dried to obtain a granular flame retardant. The solvent that can be used in this method 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 solvent, which is preferable in terms 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. 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. Next, a method of compressing the composition to form a sheet-like mass and cutting or crushing the mass will be described. The flame retardant that can be used in this method may be a powder or one that can be heated and melted in the form of a powder, and the thermoplastic resin may be one that can be similarly heated and melted in the form of a powder. These flame retardants and thermoplastic resins are then mixed in powder form to form a homogeneous composition. This composition is compressed with a heated roll or heated press to form a sheet-like mass, which is then crushed. The 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. Length is 1 to 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 others. may contain combinations of. According to the present invention, the granular flame retardant is composed of 70 to 99.5% by weight of flame retardant and 30 to 0.5% by weight of thermoplastic resin, and does not disintegrate during the process of weighing, transporting, or mixing the granular product with resin. There is no risk of dust generation. Also, a small amount of particulate flame retardant can be diluted into a large amount of resin pellets, improving mixing operations. Moreover, it can be uniformly dispersed in the resin during molding. The present invention will be explained in more detail with reference to Examples below. 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 product is extruded using a twin-screw continuous extruder (manufactured by Fukae Kogyo, FSWG type 3B).
hopper of a 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. This was then dried in a fluidized fluid dryer to remove methylene chloride, and the strength of the granular product was measured. Table 1 shows the strength of the granular products obtained in Examples.

[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.
Shown below.

[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 ×15 mm 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] 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. 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] Example 15 90 parts of flame retardant and 10 parts of thermoplastic resin were uniformly mixed as powders. Heat press the composition at 150℃,
The mixture was compressed for 3 minutes at a pressure of 50 kg/cm ² to form a 1 mm plate, and cooled to 60° C. to obtain a granular product. The strength of the obtained granules was measured. Next, 2000 parts of polystyrene resin (Estyrene G-20 manufactured by Nippon Steel Chemical 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 ×15 mm 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 7.

【table】

Claims (1)

[Scope of Claims] 1. 70 to 99.5% by weight or more of a bromine-containing aromatic or alicyclic halogen flame retardant compound or a mixture thereof for addition to a thermoplastic resin, and 30 to 0.5% by weight or less of a thermoplastic resin as a binder. A granular flame retardant for addition to thermoplastic resin molded products, characterized by containing the following. 2. The granular flame retardant according to claim 1, wherein the thermoplastic resin binder is a polymer or copolymer of monomers selected from the group consisting of styrene, butadiene, acrylic acid, and derivatives thereof.