JPS5928224B2 - Reinforced flame-retardant resin composition with improved electrical properties - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reinforced flame-retardant resin composition containing polytetramethylene terephthalate as a main component and having improved electrical properties.

Glass fiber reinforced products of polytetramethylene terephthalate are expected to be used in various industrial materials due to their well-balanced performance, and especially in electrical component applications due to their excellent insulation properties.

In recent years, the flammability of electrical component materials has become a problem.
In such applications, it has become important that the material be flame retardant.

Several methods have been proposed for making glass fiber-reinforced polytetramethylene terephthalate flame retardant from this perspective, and various halogen compounds and antimony trioxide have been added in combination as flame retardants. However, although reinforced polytetramethylene terephthalate made flame retardant by adding these halogen compounds and antimony trioxide together has some success in imparting flame retardancy, gender is degraded.

It is an extremely serious problem that the flame retardance required for electrical component applications significantly deteriorates the original electrical properties, and improvements are desired. As a composition with improved arc resistance of flame-retardant glass fiber-reinforced polytetramethylene terephthalate, a composition containing various nitrogen compounds, an antimony compound including sodium antimonate, and talc or boron nitride has already been proposed. are doing.

These compositions can improve arc resistance, but cannot sufficiently improve tracking resistance.
In addition, adding acicular calcium metasilicate has been proposed as a method to improve the arc resistance of polytetramethylene terephthalate, but this requires an extremely high addition amount and is not practical in systems containing flame retardants. Cannot be used on top.

It has also been proposed to add asbestos fibers with a large L/D to prevent flame dripping during flame retardation, but flame-retardant resin compositions containing asbestos fibers show black stains on the surface of molded products. This will significantly reduce the product value. Furthermore, it has been proposed to add silicic acid anhydride such as fumed colloidal silica or silicates for the same purpose as asbestos fibers, but even if these have the effect of suppressing flame dripping, they are not suitable for the present invention. The desired tracking resistance cannot be improved. As described above, no resin composition has been obtained which makes polytetramethylene terephthalate added with a reinforcing filler flame retardant and which does not impair the excellent electrical properties, particularly arc resistance and tracking resistance, of polytetramethylene terephthalate.

The inventors of the present invention have conducted extensive research to ensure that arc resistance and tracking resistance are not reduced when making polytetramethylene terephthalate with reinforcing fillers flame retardant. It has been discovered that when adding halogen compounds and antimony compounds as flame retardants, arc resistance and tracking resistance can be improved by using hydrated (hydrated) silicic acid, and in addition, excellent flame retardancy and mechanical properties can be achieved. It became clear that a good composition without any deterioration in physical properties etc. could be obtained, and the present invention was achieved.

This was a completely surprising fact.

This is because polytetramethylene terephthalate has ester bonds, so it tends to be easily hydrolyzed by moisture. Therefore, if a substance with such bound water is added, polytetramethylene terephthalate will be decomposed and its original excellent mechanical properties will be lost. It was thought that there would be a significant decrease in Therefore, various additives to polytetramethylene terephthalate have been proposed for various purposes, but all of them have been limited to anhydrides, or those with low crystallization water or extremely high dehydration temperatures. However, it has become clear that when hydrated (water-containing) silicic acid is used as in the present invention, the mechanical properties do not deteriorate as described above, and arc resistance and tracking resistance can be improved.

This effect can only be achieved by adding hydrated (water-containing) silicic acid, and anhydrous silicic acid or the like cannot improve arc resistance and tracking resistance.
Although the cause of this is not yet fully understood, it is assumed that this is due to the fact that anhydrous silicic acid and hydrated silicic acid have different physical and chemical surface conditions. The present invention consists of polytetramethylene terephthalate, a halogen compound necessary to make it flame retardant, an antimony compound, hydrated silicic acid, and a reinforcing filler, and the halogen compound is 3 parts by weight per 100 parts by weight of polytetramethylene terephthalate. ~50 parts by weight, an amount of the antimony compound such that the weight ratio of the halogen compound/antimony compound is 0.25 to 6;
A reinforced flame retardant resin composition with improved electrical properties in which hydrated silicic acid is 1 to 10% by weight of the total resin composition.

The polytetramethylene terephthalate used in the present invention is synthesized from, for example, 1,4-butanediol and dimethyl terephthalate, but if necessary, diols such as ethylene glycol, 1,3-propanediol, and dicarboxylic acids such as isophthalic acid may be added. A polymer co-condensed by adding a small amount may also be used, and a mixture of the polytetramethylene terephthalate obtained in this way and 40% by weight or less of another polymer is also included in the scope of polytetramethylene terephthalate in the present invention. included.

The intrinsic viscosity [η] of the polymer is 0.4 to 3.0 at 25°C in a mixed solvent of equal amounts of tetrachloroethane/phenol.
A value in the range of 0.6 to 2.5 is preferred, but a value in the range of 0.6 to 2.5 is particularly preferred in consideration of the mechanical properties of the final molded product, flowability in the injection molding process, etc. As the halogen compound, various kinds such as aromatic halogen-substituted compounds, aliphatic halogen-substituted compounds, and polymers thereof can be used.

For example, hexabromobenzene, tetrapromobisphenol A and its derivatives, tetrabromophthalic anhydride,
decapromodiphenyl ether, hexapromodiphenyl ether, trisdibromophenyl phosphate,
Tris 2,3-dipromopropyl phosphate, Tris 2,3-dichloropropyl phosphate, Cl4H
4Cll2O)Cl7H8Cll2)Cl8Hl2Cl
Examples include aliphatic cyclic compounds such as 12 and polymers such as brominated epoxy resins and brominated polyester resins, but any can be used as long as it is stable in the molding temperature range of polytetramethylene terephthalate resin. The amount of these halogen compounds added depends on the degree of flame retardancy required, but is 3 to 50 parts by weight, preferably 5 to 30 parts by weight, per 100 parts by weight of polytetramethylene terephthalate. If the amount added is less than 3 parts, a sufficient flame retardant effect cannot be obtained, and if it exceeds 50 parts, the resin properties will deteriorate. Antimony compounds include antimony trioxide and sodium antimonate.

The amount of the antimony compound added is within a range such that the weight ratio of rogen compound/antimony compound is 0.25 to 6.
When the weight ratio is less than 0.25, the amount of antimony compound added increases, resulting in a decrease in mechanical properties, while when it exceeds 6, the additive effect of the antimony compound on flame retardation becomes small. Hydrated (water-containing) silicic acid is generally called hydrated silicic acid or hydrous silicic acid, and is represented by the general formula SiO2.NH2O, with a water content of about 3 to 12% by weight, and a SiO2 content of about 80% by weight.
~92% by weight, usually containing some impurities such as metal oxides.

The hydrated silicic acid used is one produced by a method generally called a wet method, such as a method of decomposing sodium silicate or an alkaline earth metal silicate with an acid. ．． The amount of hydrated silicic acid added is 1 to 10% by weight, preferably 1 to 8% by weight of the total resin composition including the reinforcing filler.

If it is less than 1% by weight, the effect of improving electrical properties will not be sufficient, and if it exceeds 10% by weight, molding workability will deteriorate, which is not preferable.

The reinforcing filler may be in various forms such as fibrous or plate-like, such as glass fiber, carbon fiber, hoseker, asbestos fiber, talc, boron nitride, and the like.

Regarding the most common type of glass fiber, there are no particular regulations regarding its type or mixing method, and both the roping type and the short fiber dispersed type are adopted, but from the viewpoint of productivity, the short fiber dispersed type is preferred. is preferred. In this case, considering the wear of the molding machine during mixing and the cutting during the molding process, it is 0.4 to 6 mm. A length of about 0.1 to 2 mm is particularly preferred, but it is sufficient if the length of the glass fiber in the final molded product is about 0.1 to 2 mm. Commercially available glass fiber products that have been subjected to various treatments can be used as they are. The amount of reinforcing fillers such as glass fibers added is preferably in the range of 3 to 40% by weight of the total resin composition.

When it exceeds 40%, the moldability from the viewpoint of flowability deteriorates, and when it is less than 3%, the reinforcing effect is small.

The method of adding the reinforcing agent is not particularly stipulated and any usual method can be applied, but considering workability and other factors, it is recommended to mix halogen compounds, antimony compounds, hydrated silicic acid, etc. into polytetramethylene terephthalate chips. When doing so, it is preferable to add them together.

In addition to the above-mentioned reinforcing fillers, the composition of the present invention may also contain various modifiers such as flow improvers, stabilizers against light or heat, dyes and pigments, and the like.

Example 1 Polytetramethylene terephthalate (hereinafter referred to as PTMT) with an intrinsic viscosity [η] of -0.95 measured at 25°C in a mixed solvent of equal amounts of tetrachloroethane/phenol, commercially available glass with a fiber length of 3 mm and a diameter of about 10 μ Fibers, a flame retardant (A) having the structural formula, antimony trioxide, and hydrated silicic acid powder with a water content of about 8% are mixed in a V-type blender for about 5 minutes in the proportions shown in Table 1. Cylinder temperature 220
It was fed into a 40φ extruder at ~260°C.

The obtained strands were pelletized to obtain a composition. Using this pellet, injection molding was performed at a cylinder temperature of 250°C and a mold temperature of 100°C to obtain a molded article for evaluation. This molded article had an extremely good appearance. Using this molded article, IEC method NH4ClO. 1% aqueous solution, tracking resistance using platinum electrode, arc resistance based on ASTM D495, tensile strength based on ASTM D638, AST
Table 1 shows the results of a bending strength test using MD79O and a flame retardancy test based on UL-94 (1/1 thickness).

Comparative Examples 1 to 7 are compositions of the present invention in which only hydrated silicic acid was replaced with various other additives, and in which hydrated silicic acid was not added. obtained and evaluated.

In Comparative Example 3, where asbestos fibers were added, black stains appeared on the surface of the molded product, resulting in an unsatisfactory appearance.
Further, when aluminum silicate of Comparative Example 6 is added, the thermal stability is poor and the molded product becomes colored, which is not preferable. As is clear from Table 1, the composition of the present invention has improved tracking resistance, exhibits good mechanical properties equivalent to those without the addition of hydrated silicic acid, and has excellent flame retardancy.

Examples 2 to 4 PTMT with intrinsic viscosity [η] of 1.05, commercially available fiber length 3
mm chopped strand type glass fiber, flame retardant (
A), antimony trioxide, and hydrated silicic acid having a water content of about 8% were blended in the proportions shown in Table 2, and a composition was obtained using an extruder in the same manner as in Example 1.

This was injection molded and the tracking resistance and bending strength were evaluated. As is clear from Table 2, when the amount of hydrated silicic acid added is 0.3%, the effect of improving electrical properties is insufficient, and when the amount of hydrated silicic acid added is 15% by weight, the hydrated silicic acid is bulky, so it cannot be used in the extruder hopper. It was not possible to extrude due to poor biting.

Examples 5 to 7 PTMT with an intrinsic viscosity [η] of 1.15,
3.0 kg of commercially available chopped strand type glass fibers with a fiber length of 3 mm, each of the flame retardants shown in Table 3: a flame retardant consisting of a rogen compound and a brominated epoxy resin, an antimony compound and a hydrated silicic acid. The ingredients were blended in the proportions shown in the table, and a composition was obtained using an extruder in the same manner as in Example 1.

This composition was injection molded to obtain a molded article for evaluation.

The evaluation results are shown in Table 3. From Table 3, all molded products obtained from the composition of the present invention have good tracking resistance,
It exhibits arc resistance and has excellent flame retardancy.

Claims (1)

[Claims] 1 Consists of polytetramethylene terephthalate, a halogen compound necessary to make it flame retardant, an antimony compound, hydrated (water-containing) silicic acid, and a reinforcing filler, where the halogen compound is 3 to 50 parts by weight per 100 parts by weight of polytetramethylene terephthalate. parts by weight, antimony compound in an amount such that the weight ratio of halogen compound/antimony compound is 0.25 to 6, and hydrated (water-containing) silicic acid in an amount of 1 to 10% by weight of the total resin composition.Improved electrical properties. Reinforced flame retardant resin composition.