JPH0718165A - Flame-retardant polyester resin composition - Google Patents

Abstract

PURPOSE:To obtain a flame-retardant polyester resin composition which can be optimally used as a molding material for thinwalled small-size parts and can be injected with reduced pressure as a sealing material for coil bobbins because of its reduced viscosity. CONSTITUTION:This flame-retardant polyester resin composition is essentially composed of 100 pts.wt. of polyester resin, 10 to 60 pts.wt. of brominated polystyrene of which more than 20wt.% is the brominated polystyrene of 1,000 to 18,000 weight-average molecular weight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant polyester resin composition having a low viscosity, which is suitable as a molding material for thin-walled and small-sized parts and is suitable as a sealing material.

[0002]

2. Description of the Related Art It has been widely known that brominated polystyrene is used as a flame retardant for polyester.

However, the conventional flame-retardant polyester resin composition containing brominated polystyrene (weight average molecular weight of 120,000 or more) has a high viscosity and is not sufficient as a molding material for thin-walled / small parts. Further, when a conventional flame-retardant polyester resin composition containing brominated polystyrene is used as a sealing material such as a coil bobbin, an unfilled portion occurs at a low injection pressure, and when a normal injection pressure is used, the magnet wire is deformed or The problem of cutting occurs.

[0004]

The present invention solves the above-mentioned drawbacks of the prior art, is most suitable as a molding material for thin-walled and small-sized parts, and has a low viscosity that enables low-pressure injection as a sealing material for coil bobbins and the like. An object is to provide a flammable polyester resin composition.

[0005]

The present invention which achieves the above object consists essentially of 100 parts by weight of a polyester resin and 10 to 60 parts by weight of brominated polystyrene, and 20% by weight or more of the brominated polystyrene is A flame-retardant polyester resin composition characterized by being a brominated polystyrene having a weight average molecular weight of 1,000 to 18,000.

The polyester resin used in the present invention is preferably polyalkylene terephthalate, and particularly preferably polyethylene terephthalate. Polyethylene terephthalate is preferably used which has an intrinsic viscosity of at least about 0.4 at 30 ° C. in methylene chloride and trifluoroacetic acid in a volume ratio of 3: 1 and which has an intrinsic viscosity of up to about 1.2. Is preferred.

The brominated polystyrene used in the present invention is, for example, polydibromostyrene, polytribromostyrene,
Known brominated polystyrene such as polypentabromostyrene can be used, but the content thereof is 10 to 60 parts by weight with respect to 100 parts by weight of the polyester resin, and 20% by weight or more of the brominated polystyrene contained. Is
The weight average molecular weight is 1,000 to 18,000. The weight average molecular weight is measured by gel permeation chromatography (GPC) using chloroform. When the content of brominated polystyrene is less than 10 parts by weight, the flame retardancy does not become V-0 (UL94), and when it is more than 60 parts by weight, mechanical properties are deteriorated, which is not preferable. Further, the weight average molecular weight is 1,000 to 18,000.
When the content of the brominated polystyrene is less than 20% by weight based on the whole brominated polystyrene, the viscosity is high and the object of the present invention cannot be achieved. Weight average molecular weight is 1
More than 8,000 brominated polystyrene and 1,000-1
The appropriate mixing ratio with brominated polystyrene of 8,000 depends on the application. When a large amount of low molecular weight brominated polystyrene is mixed, the viscosity of the polyester resin composition becomes low, but the low molecular weight brominated polystyrene is more likely to adversely affect the mechanical properties of the polyester resin than the high molecular weight brominated polystyrene. Therefore, specifically, the mixing ratio is determined in consideration of the balance between viscosity and mechanical properties depending on the application.

Glass fiber contained in the composition of the present invention,
The filler such as mica, whiskers, synthetic resin fibers is a mixture of polyester resin and brominated polystyrene.
1 to 200 parts by weight can be added to 0 parts by weight.

Further, the polyester resin composition of the present invention, especially the polyethylene terephthalate composition, preferably contains a nucleating agent in order to improve the low temperature moldability. As the nucleating agent, a sodium compound and / or a potassium compound can be used. Part or all of these sodium compounds and / or potassium compounds may be replaced with talc. Various nucleating agents can also be used. Further, a part or all of the polyester, which is the main component of the present invention, may be replaced with polyethylene terephthalate having a terminal sodium or potassium. This end-treated polyethylene terephthalate is described in U.S. Pat. No. 4,425,470 and can be produced by the method described therein. If this terminal sodium or potassium-modified polyethylene terephthalate is used, it may not be necessary to add a nucleating agent separately.

The polyester resin composition of the present invention may contain additives such as a heat stabilizer, a plasticizer, an antioxidant, a dye, a pigment and a release agent in addition to the above components to the extent that the characteristics thereof are not impaired. It can be blended.

In order to produce the polyester resin composition of the present invention, a method of melt kneading is used, and a kneading device such as a Banbury mixer, an extruder and various kneaders which are generally used can be used. Regarding the kneading order when the polyester resin composition of the present invention is produced, the respective components may be kneaded at once, or the filler may be supplied from the side feeder.

[0012]

In the present invention, low molecular weight brominated polystyrene is used in place of conventional brominated polystyrene in consideration of mechanical properties, so that the viscosity of the polyester resin as a whole can be reduced and thin-walled / small-sized parts can be manufactured. A flame-retardant polyester resin composition which is most suitable as a molding material and can be injected at low pressure as a sealing material.

[0013]

The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples.

The compositions of Examples 1 to 4 and Comparative Example 1 containing the components shown in the following Table 1 were prepared, and the measurement results of the physical properties shown in the same table were obtained.

[0015]

[Table 1]

The following components were used in these examples and comparative examples. Polyethylene terephthalate (P
ET) is manufactured by DuPont and has an intrinsic viscosity of about 0.6.
It is 7 to 0.58. As the high molecular weight brominated polystyrene, polytribromostyrene having a weight average molecular weight of 150,000 to 170,000 (Pyrocheck 68PB manufactured by Ferro Corporation) was used. As the low molecular weight brominated polystyrene, polytribromostyrene having a weight average molecular weight of 1,000 to 18,000 (Pyrocheck LM manufactured by Ferro Corporation) was used.

Surlyn 8 manufactured by DuPont as another nucleating agent
920 was used. Plasticizers and antioxidants were also added to each composition sample.

The resin, the nucleating agent and other additives in the parts by weight shown in Table 1 were premixed in a tumbler for 20 minutes, and then a twin-screw extruder TEM35B manufactured by Toshiba Machine Co., Ltd. was used.
A resin composition was obtained by melt-kneading at a temperature of 0 ° C. The melt viscosity of these resin compositions was measured using a Capillograph manufactured by Toyo Seiki. Here, the standard melt viscosity when dried is
Using pellets with a moisture content of 0.02% or less, resin temperature 2
Shear rate of 1216 (sec ^-1 ) at 80 ° C and residence time of 3 minutes
It is the melt viscosity at. The melt viscosity at the time of residence means that a resin having a water content of 0.02% or less is used at a resin temperature of 280.
Melt viscosity at a shear rate of 1216 (sec ⁻¹ ) at a temperature of 30 ° C. for a residence time of 30 minutes. The retention rate of melt viscosity at the time of retention is calculated by the following formula.

[0019]

(1) Melt viscosity retention rate during residence (%) = (A / B) × 100 A = melt viscosity during residence, B = standard melt viscosity during drying For the physical property test, this resin composition was heated at 135 ° C. for 3 hours. After drying, a standard physical property test piece was prepared using a molding machine at 290 ° C. and a mold temperature of 110 ° C. for the polyethylene terephthalate composition, and the mechanical properties of the resin composition during drying were measured. The tensile test is ASTM-
638, and the bending test was performed according to ASTM-790. The Izod impact test was based on D-256. Furthermore, the flammability is 1/32 inch (about 0.8m)
It measured based on UL94 using the test piece of m).

The melt viscosity of each of the examples is lower than that of the comparative example. Therefore, it is clear that the melt viscosity becomes low by containing the low molecular weight polytribromostyrene.

From the examples, it can be seen that as the content of low molecular weight polytribromostyrene increases, the melt viscosity decreases and the mechanical properties decrease. Therefore, the blending amount is appropriately determined in consideration of the balance between mechanical properties and viscosity according to the application.

Further, it can be seen that the melt stability is also improved with respect to the value of the comparative example.

[0023]

As described above, the polyester resin composition of the present invention has a weight average molecular weight of 1,00 to 18,0.
It is a flame-retardant polyester resin composition that has a low viscosity and is suitable as a molding material for thin-walled and small parts because it is a flame-retardant polyester resin composition that can be injected at low pressure. is there.

Furthermore, since the polyester resin composition of the present invention has high melt stability, it is possible to obtain an excellent molded product which is less likely to cause flash during molding, has a good appearance, and has less variation in size and weight. it can.

Claims (2)

[Claims] 1. A brominated product essentially consisting of 100 parts by weight of a polyester resin and 10 to 60 parts by weight of brominated polystyrene, and 20% by weight or more of the brominated polystyrene has a weight average molecular weight of 1,000 to 18,000. A flame-retardant polyester resin composition, which is polystyrene. 2. A flame-retardant polyester resin composition comprising 100 parts by weight of the polyester resin composition according to claim 1 and 1 to 200 parts by weight of a filler.