JPS6358861B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for improving the flame retardancy of a polyester resin composition, and particularly to a method for providing a polyester resin composition that does not drip melt during combustion. [Prior Art] Thermoplastic polyester resins, particularly polyalkylene terephthalate resins, have high heat resistance and excellent physical properties such as mechanical properties, electrical properties, and chemical resistance, and are widely used in industrial products. However, the polyester resin has the disadvantage that it does not have sufficient flame retardancy and is relatively easy to burn. Various methods have been proposed to impart flame retardancy to this polyester resin. For example, flame retardant methods include adding various organic halogen compounds and phosphorus compounds in combination with flame retardant aids, and reacting halogen compounds with polymer skeletons. Practically useful polyester resin compositions can be obtained by these methods in many cases, but it may be difficult to make them flame retardant when the product is very thin, for example, a product with a thickness of 1 mm or less. be. In other words, in order to obtain the desired flame retardancy in such flakes, it can be achieved by adding a large amount of the above-mentioned organic halogen compounds and flame retardant aids, but it is not only economical but also difficult to obtain the resulting product. This inevitably leads to a decrease in strength and other impractical properties. As a means of improving the flame retardancy of such flakes, polyester compositions that do not melt and drip during combustion (and therefore have good shape retention) have also been proposed. As additives to prevent this melt dripping, for example, asbestos fibers may be added (Tokuko Showa).
51-24538) and adding tetrafluoroethylene (Japanese Patent Application Laid-open No. 47-42942). However, these additives (anti-dripping agents)
When adding , there is a drawback that it inevitably leads to a decrease in physical properties, especially a decrease in impact strength and elongation. [Object of the Invention] The present invention was made against the background of the above circumstances, and its purpose is to obtain a flame-retardant polyester resin composition that does not cause melting and dripping during combustion and has good characteristics. There is a particular thing. [Structure of the Invention] A method for improving the flame retardancy of the polyester resin composition of the present invention to achieve the above object is shown as follows. That is, 0.1 to 10% by weight of sepiolite (based on the composition) is added to a polyester resin composition comprising at least a linear aromatic polyester, an organic halogen compound, and an inorganic flame retardant aid, and optionally further containing an inorganic reinforcing agent.
This is a method for improving the flame retardancy of a polyester resin composition. The linear aromatic polyester as used in the present invention means a polymer that can be obtained by polycondensation of an aromatic dicarboxylic acid and/or an aromatic oxycarboxylic acid and a diol. Typical aromatic dicarboxylic acids include terephthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, etc., and typical aromatic oxycarboxylic acids include oxybenzoic acid, hydroxyethoxybenzoic acid, etc. Illustrated. These may be used alone or in combination of two or more. Further, typical diols include lower alkylene glycols such as ethylene glycol, trimethylene glycol, tetramethylene glycol, and hexamethylene glycol. These may be used alone or in combination of two or more. Typical examples of such polyesters include polyethylene terephthalate, polybutylene terephthalate, hexamethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyhexamethylene naphthalate, polyhexamethylene-4,
Examples include 4'-diphenyldicarboxylate. The organic halogen compound used in the present invention refers to a compound that is generally treated as a halogen flame retardant, but in consideration of the heat history received during the molding process of the polyester resin composition, aromatic halogen compounds with excellent heat resistance are preferred. Examples include decabromodiphenyl ether, halogenated polycarbonates such as brominated polycarbonate obtained from tetrabromobisphenol A and phosgene, brominated copolycarbonates obtained from tetrabromobisphenol A, bisphenol A and phosgene, and tetrabromo Examples include halogenated epoxy compounds such as a brominated epoxy compound obtained from bisphenol A and epichlorohydrin, brominated polystyrene, brominated polyphenylene oxide, and the like. The amount of the additive may be the amount generally adopted, but it varies depending on the degree of flame retardance required, and 1
It is preferably in the range of ~30% by weight, and more preferably 2~20% by weight. That is, if it is less than 1% by weight, the flame retardance may be insufficient, and if it exceeds 30% by weight, the properties of the resulting composition may be significantly deteriorated. The inorganic flame retardant aid used in the present invention is generally a compound that facilitates flame retardation of the composition when used in combination with an organic halogen compound. Examples include antimony trioxide, antimony pentoxide, and sodium antimonate. compounds and barium metaborate,
Examples include boron compounds such as zinc borate. The amount of this inorganic flame retardant aid added is 0.5 per total composition.
-20% by weight, more preferably 1-10% by weight. That is, if it is less than 0.5% by weight, the flame retardant effect is not sufficient;
Moreover, if it exceeds 20% by weight, the properties of the composition will deteriorate significantly, which is undesirable. The inorganic reinforcing agent used in the present invention is optionally added to impart necessary functions depending on the use and purpose. Inorganic reinforcing agents include those with various properties. For example, fibrous reinforcing agents such as glass fiber, carbon fiber, potassium titanate fiber, wollastonite, spherical reinforcing agents such as glass beads,
Examples include plate-like reinforcing agents such as glass flakes, talc, and mica, and amorphous reinforcing agents such as feldspar, calcium carbonate, and silica. The amount added is preferably 0 to 60% by weight based on the total composition. That is, if it exceeds 60% by weight, not only the molding processability of the composition deteriorates, but also the mechanical properties are significantly deteriorated, which is undesirable. Sepiolite used in the present invention is Mg ₈ Si ₁₂ O ₃₀
It is a hydrous magnesium silicate salt represented by (OH) ₄ ·xH ₂ O (where x is an integer of 6 to 8). The amount added is preferably 0.1 to 10% by weight, more preferably 0.2 to 5% by weight, based on the total composition. In other words, if it is less than 0.1% by weight, the effect of preventing melt dripping during combustion is insufficient, and if it exceeds 10% by weight, the desired effect of preventing melt dripping will not only reach saturation, but also cause the composition to deteriorate. This is not preferred because it involves a significant decrease in strength. The flame-retardant polyester resin composition obtained according to the present invention may contain additives other than those mentioned above in order to impart other required properties. These additives include heat stabilizers (for example, phosphorus compounds, etc.), antioxidants (for example, phenol compounds, etc.), crystal nucleating agents (for example, metal salts of organic acids, etc.), mold release agents, colorants, ultraviolet absorbers, and Examples include antistatic agents. Additionally, the combined addition of a diepoxy compound, which is generally added to improve the strength of polyester, is also effective in improving properties. Furthermore, addition of other types of polymers, particularly polycarbonate, polyolefins, acrylic elastomers, etc., is effective in improving the impact strength of the polyester composition. Although any physical means can be used to prepare the composition of the present invention, the most common and desirable method is to blend polyester and each additive in a predetermined amount and then melt-knead it in an extruder. An example of this method is to homogenize the pellet, then pelletize it and use it for molding. The composition of the present invention is used as a molding material, and is particularly preferably used as a material for injection molding or extrusion molding. [Example] The present invention will be explained in detail with reference to Examples below. The method for measuring the main characteristics is as follows. Flammability: UL standard Subject94 Impact strength: ASTM standard D-256 (with Izod notch) Examples 1-4, Comparative Examples 1-2 Intrinsic viscosity [η] (measured at 35°C using O-chlorophenol as a solvent) 0.75 dry polybutylene terephthalate (hereinafter abbreviated as PBT) pellets, decabromodiphenyl ether, antimony trioxide, glass fiber, and sepiolite were mixed in a V-type blender in the proportions shown in Table 1, and this was extruded to 65 mmφ. Supply to the machine, cylinder temperature 270℃
The mixture was pelletized to obtain pellets for molding. After drying the pellets at 130℃ for 3 hours, the cylinder temperature was 270℃ using a 5-ounce injection molding machine.
Test pieces for combustion tests and impact tests were obtained at an injection pressure of 800 Kg/cm ² , a mold temperature of 70° C., and a molding cycle of 35 seconds. Table 1 shows each characteristic value evaluated using this test piece.

[Table] Note) In terms of flammability 〓
Examples 5 to 7, Comparative Examples 3 to 4 The organic halogen compounds shown in Table 2 were used in place of the decabromodiphenyl ether used in Examples 1 to 4. Characteristics were evaluated in the same manner as in Examples 1 to 4, except that they were used. The results are shown in Table 2.

〔Effect of the invention〕

As described above, it is clear that the composition of the present invention has excellent flame retardancy without melting and dripping during combustion without impairing the excellent mechanical properties of polyester resin.

Claims (1)

[Claims] 1. A polyester resin composition comprising at least a linear aromatic polyester, an organic halogen compound, and an inorganic flame retardant aid, and optionally further containing an inorganic reinforcing agent, contains 0.1 to 10% by weight (based on the composition) of sepiolite. A method for improving flame retardancy of a polyester resin composition.