JPS6017308B2 - Flame-retardant resin composition with improved electrical properties - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin composition that is flame retardant and has excellent tracking resistance, arc resistance, and mechanical and thermal properties.

Polytetramethylene terephthalate is expected to be used in various industrial materials due to its well-balanced performance. In particular, it is expected to be used in electrical parts because of its excellent insulation properties. However, in recent years, the flammability of electrical component materials has become a problem, and flame retardancy has become extremely important for such uses. From this point of view, several methods have been proposed for making polytetramethylene terephthalate scaly, and various halogen compounds and antimony trioxide are added in combination as flame retardants.

However, when the present inventors conducted a detailed evaluation study on polytetramethylene terephthalate made flame retardant by adding these halogen compounds and antimony trioxide together, they found that they were tentatively successful in imparting flame retardancy. However, it was found that the electrical properties, especially tracking resistance and arc resistance, were poor. It is an extremely serious problem that the flame retardance required for electrical component applications significantly degrades the originally excellent electrical properties, and improvements are desired. As compositions with improved arc resistance of flame-retardant polytetramethylene terephthalate, compositions in which various halogen compounds, antimony compounds containing sodium antimonate, or further talc or shelchloride nitride are added have been proposed.

Although this composition was able to sufficiently improve arc resistance, it was still not possible to sufficiently improve tracking resistance. Adding acicular calcium metasilicate has been proposed as a method of improving the arc resistance of POIJ tetraethylene terephthalate, which does not contain flame retardants, but it requires an extremely high amount of addition, and it is necessary to add acicular calcium metasilicate to the flame retardant. It cannot be used practically in systems containing

There is also a proposal to improve the tracking resistance by adding a filler such as talc to a mixture of polytetramethylene terephthalate and polyolefin.

However, in order to sufficiently improve the tracking resistance, it is necessary to increase the amount of polyolefin added, and as a result, the excellent mechanical and thermal properties inherent to polytetramethylene terephthalate are lost. Furthermore, even when a flame retardant is blended into this system, if the tracking resistance is increased, the flame retardance decreases rapidly, causing the problem that the self-extinguishing property is not satisfied. In this way, a resin composition that imparts a high degree of flame retardancy to polytetramethylene terephthalate, maintains the excellent mechanical and thermal properties inherent to polytetramethylene terephthalate, and improves tracking resistance and arc resistance. The current situation is that it has not been obtained.

The present inventors have discovered that when making polytetramethylene terephthalate flame retardant, it is necessary to maintain its original excellent mechanical and thermal properties and improve tracking resistance and arc resistance. A high degree of flame retardancy can be imparted by blending terephthalate with a methacrylic polymer containing at least 50% by weight of methyl methacrylate, and a halogen compound and an antimony compound as flame retardants and an inorganic filler. They also found that the synergistic effect of the methacrylic polymer and the inorganic filler significantly improved tracking resistance and arc resistance, and found that it was possible to obtain a composition that not only had excellent mechanical and thermal properties but also had superior mechanical and thermal properties. This became clear and led to the present invention.

The present invention provides polytetramethylene terephthalate 95-3
At least 5 parts by weight of methyl methacrylate polymerized with 5 parts by weight
to a polymer mixture consisting of 5 to 65 parts by weight of a methacrylic polymer containing 3 to 4 parts by weight of a halogen compound and 1 to 3 parts by weight of an antimony compound as a retardant, and a non-conductive inorganic material. This is a flame-retardant resin composition with improved electrical properties, which is obtained by adding a filler in an amount of 3 to 7% by weight based on the total resin composition.

The composition of the present invention may also contain reinforcing glass fibers in an amount of up to 4% by weight based on the total resin composition, if necessary. In this case, it is preferable to adjust the amounts of other additives so that the resin component is 25% by weight or more. Here, polytetramethylesoterephthalate is synthesized from, for example, 1,4-butanediol and dimethyl terephthalate. Furthermore, if necessary, a polymer co-condensed with a small amount of diol such as ethylene glycol, 1,3-propanediol, or dicarboxylic acid such as isophthalic acid may be used. Mixtures with polyethylene terephthalate or polypropylene terephthalate may also be used. Intrinsic viscosity of polymer [
As for this, a solvent with a value in the range of 0.3 to 3.0 in 100 cc of an equal amount of tetrachloroethane/phenol mixed solvent is used. In consideration of mechanical properties, flow processability in the injection molding process, etc., a range of 0.5 to 1.7 is particularly preferable. Examples of methacrylic polymers include methyl methacrylate homopolymers, methyl methacrylate-methyl acrylate copolymers, methyl methacrylate-methacrylic acid copolymers, methyl methacrylate-acrylic acid copolymers,
Methyl methacrylate-styrene copolymer, methyl methacrylate-acrylonitrile copolymer, methyl methacrylate-styrene-acrylonitrile copolymer, methyl methacrylate-methyl acrylate-methacrylic acid copolymer, methyl methacrylate monobutadiene-styrene A copolymer is used, but in the case of a copolymer, it is necessary to contain at least 5% by weight of polymerized methyl methacrylate, and if it is less than that, the tracking resistance improvement that is the objective of the present invention will not occur. The effect is not fully demonstrated. These polymers are synthesized by known methods using a radical polymerization initiator and conventional polymerization methods such as solution polymerization, suspension polymerization, emulsion polymerization, or bulk polymerization.

In many cases, the intrinsic viscosity of these polymers is 0.3-2.
A value in the range 0 is used. The blending ratio of these methacrylic polymers and polytetramethylene terephthalate is 5 to 65 parts by weight of the methacrylic polymer to 95 to 35 parts by weight of polytetramethylene terephthalate.

If the amount of the methacrylic polymer added is less than 5 parts by weight, the synergistic effect with the non-conductive inorganic filler on improving tracking resistance will not be exhibited. If more than 65 parts by weight is added, the properties of polytetramethylene terephthalate are rapidly lost, and heat resistance etc. are greatly reduced. As the halogen compound used in the present invention, various compounds such as aromatic halogen substituted compounds, aliphatic halogen substituted compounds, and further halogenated polymers can be used, such as hexapromobenzene, tetrabromobisphenol S, and tetrapromobisphenol S. Phenol A and its conductors, tetrabromophthalic anhydride, decabromodiphenyl ether, hexapromodiphenyl ether, tris dibromophenyl phosphate, tris 2,3 dichloropropyl phosphate, C, 4AC1
Examples include aliphatic cyclic compounds such as , 20, C, 7 days, 8 CI, 2, C, 8 days, 2 CI, 2, polymers such as brominated epoxy resins, brominated polyester resins, brominated polycarbonate resins, etc. polytetramethylene terephthalate,
Any material can be used as long as it is stable at the molding temperature of the methacrylic polymer.

The amount of these halogen compounds added depends on the degree of flame retardancy required, but is 3 to 4 parts by weight, preferably 5 to 4 parts by weight, based on 10 parts by weight of the resin of polytetramethylene terephthalate and methacrylic polymer. It is 3 parts by weight.

If the amount added is less than 3 parts by weight, a sufficient combustion effect cannot be obtained, and if it exceeds 40 parts by weight, the mechanical properties will deteriorate. Examples of the antimony compound used in combination include antimony trioxide and sodium antimonate.

The amount of the antimony compound added is 1 to 30 parts by weight based on 10 parts by weight of the resin. If it is less than 3 parts by weight, the synergistic effect on combustion with the halogen compound will be small, and if it exceeds 3 parts by weight, the mechanical properties will be significantly deteriorated. When a particularly high flame retardant effect is required, it is preferable that the weight ratio of the halogen compound/antimony compound is in the range of 0.25 to 5/1. In the present invention, the inorganic filler that synergistically improves tracking resistance and arc resistance with the methacrylic polymer can be of various shapes, but it is necessary that it is non-conductive. Powders of simple metals that exhibit conductivity are excluded.

Specific examples of non-conductive inorganic fillers include talc, kaolin, clay, mica powder, calcium silicate, calcium carbonate, silicic acid, hydrated silicic acid, glass powder, glass powder,
These include dawsonite, nitride shelving, shelving sand, shelving zinc, asbestos, alumina, aluminum hydroxide, iron sulfate, etc. The amount of these non-conductive inorganic fillers added is 3 to 7% by weight based on the total resin composition. If the amount is less than 3% by weight, the synergistic effect with the methacrylic polymer on tracking resistance will not be sufficiently exhibited, and if it is added in excess of 7% by weight, moldability will deteriorate, which is not preferred.

In particular, in the present invention, due to the synergistic effect of the methacrylic polymer and the non-conductive inorganic filler, the tracking resistance can be improved with a much smaller amount of addition compared to the case of the inorganic filler alone, so it is usually less than 5% by weight. is sufficient. Additionally, reinforcing glass fibers may optionally be added to the compositions of the present invention in amounts up to 4% by weight based on the total resin composition. Of course, there are no particular regulations regarding the type of glass fiber used or the method of mixing it; roving type,
Although any type of short fiber dispersion can be adopted, the short fiber dispersion method seems to be preferable from the viewpoint of productivity. In this case, in consideration of workability during mixing, abrasion of the molding machine, or cutting during the molding process, it is particularly preferable to have a side of about 0.4 to 6.
It is sufficient that the length of the glass fibers in the final molded product is about 0.1 to 2 skins long. Commercially available glass fibers that have been subjected to various treatments are used as they are. If the amount of glass fiber added exceeds 40% by weight, it is not preferable because the molding processability from the viewpoint of flow processability decreases. To obtain the composition of the present invention, any method well known to those skilled in the art can be applied, such as polytetramethylene terephthalate, methacrylic polymer, halogen compound, antimony compound, and non-conductive inorganic filler, Further, glass fibers are mixed in a blender or the like, fed to an extruder hobber, melt-mixed, and formed into a pellet shape or the like.

The composition of the present invention thus obtained exhibits a high degree of flame retardancy, high tracking resistance, and arc resistance, and is used for electrical parts such as breaker switches and live part support materials, and for parts under the hood of automobiles. etc. is extremely useful.
The composition of the present invention may include various modifiers, stabilizers,
A nourishing agent, a pigment, etc. are also added.

Examples 1 to 4 Polytetramethylene terephthalate (PTMT) with an intrinsic viscosity of 0.90 at 25 qC in a mixed solvent of equal amounts of tetrachloroethane/phenol, and an intrinsic viscosity of 0.90 at 2500 in chloroform. Table 1 shows polymethyl methacrylate (PMMA) of No. 6, bisphenol A type brominated epoxy resin with a bromination rate of 50% as a halogen compound, antimony trioxide, commercially available fiber length 3 willow chopped strand type glass fiber, and a tank. Each proportion was weighed and mixed in a V-type blender for about 5 minutes.

This was passed through a 400 pent type extruder and formed into a pellet shape to obtain the composition of the present invention. The composition was molded using a 360 screw injection molding machine at a cylinder temperature of 270 oo and a mold temperature of 100° C. for evaluation of flame retardancy, electrical properties, and mechanical and thermal properties.

These evaluation results are shown in Table 1. As is clear from Table 1, the tracking resistance and arc resistance of the molded article obtained from the composition of the present invention are significantly improved due to the synergistic effect of the methacrylic polymer and the non-conductive inorganic filler. It also has good thermal properties.

On the other hand, Comparative Example 1 is inferior in tracking resistance and arc resistance without the addition of PMMA and tan, and even if only talc is used as in Comparative Example 2, the tracking resistance and arc resistance cannot be sufficiently improved.

Comparative Example 3 consists of exactly the same components as the composition of the present invention, but the blending ratio of PTMT-PMMA is outside the scope of the present invention, and if the amount of PMMA added is too large, the mechanical properties and heat resistance will deteriorate. This is not desirable. Comparative Examples 4 and 5 use polypropylene instead of PMMA in the compositions of the present invention, and have good electrical properties but are flammable, but have poor mechanical and thermal properties, so they are not suitable for practical use. do not have.
The composition of the present invention provides a molded article with excellent electrical properties, flame retardance, and mechanical and thermal properties due to the synergistic effect of the methacrylic polymer and the inorganic filler. In the table, flame retardancy is UL
The test results are based on 5 samples with a thickness of 1/16" based on the IEC method. Tracking resistance was conducted using an aqueous solution with an N ratio of CIO.1% and a platinum electrode. Arc resistance was determined using ASTM D49i tensile strength. Strength is ASTM D63
& Bending strength is ASTMD790, heat distortion temperature is AST
It was measured using MD648. Examples 5 to 8 PTMT with an intrinsic viscosity of 0.85, an intrinsic viscosity of 0.85
0.51 methyl methacrylate-methyl acrylate (MA) copolymer (PMMA/PMA weight ratio 87/1
3) Flame retardant [A] with the following structural formula, brominated epoxy resin with bromination rate of 51%, antimony trioxide, commercially available chopped strand type glass fiber (fiber length 3 willow), and thickness of 32 mesh pass About 21 pieces of glass powder were weighed and mixed in the proportions shown in Table 2 to obtain a composition of the present invention in the same manner as in Example 1.

These compositions were molded in the same manner as in Example 1, and the results of evaluation are shown in Table 2. As is clear from Table 2, if the amount of the non-conductive inorganic filler added is too small, the tracking resistance and # resistance will deteriorate. The effect of improving arc properties is not sufficient, and if the glass fiber and inorganic filler content is too high (9% by weight) as in Comparative Example 7, extrusion is impossible.

That is, the upper limit of the amount of non-conductive inorganic filler added is not from the viewpoint of improving electrical properties, but from the viewpoint of flowability, it is 7% by weight or less. Table 2 Examples 9 to 12 PTMT with an intrinsic viscosity of 1.05, methacrylic copolymer shown in Table 3, halogen compound, sodium antimonate, commercially available chopped strand type glass fiber with fiber length 3 side, and white power A composition of the present invention was obtained in the same manner as in Example 1 by weighing and mixing -bon in the proportions shown in Table 3.

These compositions were molded in the same manner as in Example 1, and the results of evaluation are shown in Table 3.

As is clear from Table 3, the molded articles obtained from the compositions of the present invention exhibit good tracking resistance and arc resistance.

In the table, MMA means methyl methacrylate, MAA means methacrylic acid, AN means acrylonitrile, St means styrene, MA means methyl acrylate, and Bd means butadiene.

Moreover, the polymerization ratio of the methacrylic copolymer is indicated by the weight ratio of each copolymer component. Table 3

Claims (1)

[Claims] 1 Add halogen as a flame retardant to 100 parts by weight of a polymer mixture consisting of 5 to 65 parts by weight of a methacrylic polymer containing at least 50% by weight of methyl methacrylate polymerized with 95 to 35 parts by weight of polytetramethylene terephthalate. A flame-retardant resin composition comprising 3 to 40 parts by weight of a compound, 1 to 30 parts by weight of an antimony compound, and 3 to 70 parts by weight of a non-conductive inorganic filler based on the total resin composition.