DE2405325A1 - FLAME-RESISTANT, REINFORCED POLYESTER MOLDING COMPOUNDS - Google Patents

Description

The invention relates to glass fiber reinforced, flame retardant molding compositions based on linear saturated polyesters, in particular polybutylene terephthalate.

From DT-OS 2 158 432 it is known that glass fiber reinforced Polyester can be equipped with a flame retardant system composed of an aromatic halogen compound and a metal oxide. In order to prevent the polymer from dripping off during firing, an additional long-fiber reinforcing filler should be used can be added.

The halogenated aromatics used there as flame retardants have the disadvantage that they are not biodegradable, so that other suitable flame retardant systems had to be found.

It has now been found that cycloaliphatic chlorine compounds can be used for the stated purpose. Are particularly cheap those chlorine compounds in which no chlorine atom is in direct proximity to a hydrogen atom. You can either-

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for example, by Diels-Alder addition of hexachlorotpentadiene to an olefin such as cyclooctadiene-1,5, furan, cyclopentadiene, dicyclopentadiene, dicyclo- (2,2,2) -heptadiene or tetrabromostyrene. It was surprising that these chlorine compounds are stable at the high processing temperatures that must be used in polyesters. "In contrast, the usual for flameproofing aliphatic chlorinated compounds are not suitable because they split off at temperatures above von'200 ⁰ C hydrogen chloride. The chlorine compounds

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werden.in amounts of from 5 to 30, preferably from 10 to 20 weight percent, based on the total molding composition. Their chlorine content should be above 50, preferably between 60 and 85 percent by weight.

The molding compounds also contain 0.5 to 10, preferably 2 up to 6 percent by weight of a synergistic metal oxide of main group V of the Periodic Table, preferably antimony trioxide.

Suitable polyesters are polyethylene terephthalate and polypropylene terephthalate and polybutylene terephthalate and corresponding mixed polycondensates. Preferably they are made from terephthalic acid and 1,4-butanediol built up. Up to 15 mole percent can be used of terephthalic acid by other aromatic or aliphatic dicarboxylic acids, such as isophthalic acid, naphthalenecarboxylic acid, Adipic acid or sebacic acid. Similarly, up to 15 mole percent of the butanediol can be replaced by other diols, e.g. Glycol, propanediol, hexanediol, ^ bisoxylated bisphenol A, replaced will. The polyesters which are produced by known processes have K values, measured by the method of Fikentscher, Cellulosechemie IjJ (1932), p. 58, in a mixture

from phenol and o-dichlorobenzene at 25 ° C. in a concentration of 0.5 g / 100 ml between 55 and 80, preferably between 60 and 75.

The glass fibers used for reinforcement have a thickness of more than 5 μm, preferably from 8 to 20 μm. Your length in the finished molding compounds is generally between 0.05 and 1.0 mm, preferably between 0.1 and 0.5 mm. You can how common practice, with adhesion promoters, preferably based on silane and treated with sizing agents. The glass fiber content of the molding compounds is between 10 and 60 percent by weight. The glass fibers can be incorporated in the form of cut fiberglass or in the form of endless rovings. The molding compounds You can also use customary additives, such as stabilizers, pigments, dyes or lubricants, and other plastics contain.

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In addition to the glass fibers described, the molding compounds contain still 0.5 to 15, preferably 1.5 to 12 percent by weight another fibrous material. These fibers have a thickness of less than 5 / µm, preferably from 0.05 to 2 Aim, The ratio of length to thickness is in general greater than 20 s 1. Fibers made of asbestos, glass, aluminum are suitable rinium oxide, zirconium oxide or silicon carbide. Fibrous chrysotile asbestos and single crystals of potassium titanate are particularly preferred.

The additional fibers represent a kind of framework that holds the polymer melt together when the molding compounds are exposed to a flame, so that no dripping of burning polymer can take place. This is particularly important for thin molded parts or profiles, where, due to the large surface area exposed to the flame, the melting process is faster than the flame retardant effect the chlorine compound. This is especially the case with molded parts that are thinner than 3 * 5 now.

The incorporation of the flame retardants is expediently carried out together with the fibers in conventional mixing devices, such as extruders, Rolling or kneading, at temperatures between 240 and 260 ° C.

example

Polybutylene terephthalate with a K value of 70.2 was melted on a single-screw extruder. Flame retardants and fibers were added to the feed hopper at the same time as the granulate. The flame retardant used was an addition product of 2 moles of hexachlorocyclopentadiene and 1 mole of cyclooctadiene (I) or furan (II). The granules of the glass fibers had a thickness of 10 μm and an average length of 0.25 μm. As an additional fiber, asbestos fibers with a thickness of J500 8 and a length to thickness ratio of 100 to 1,000 s-1 and potassium titanate fibers with a thickness of 0.1 to 0.16 µm and a length to thickness ratio of 40 were used : 1 used. The polybutylene terephthalate / fibers / flame retardant mixture, which was not ^{heated above 265 °} C. when mixed in the extruder, was pressed out through nozzles and drawn off as a strand

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and crushed with a cutting machine.

From this granulate, test specimens with dimensions of 6x5.5 χ 12.7 x 3 * 2 mm were injected on a screw injection molding machine, which have been tested for their fire behavior based on UL test 94 (Underwriters Laboratories). The received Data are summarized in the table.

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Tabel

Fire behavior of polybutylene terephthalate with "30 % glass fibers

ι
σ \
ι attempt further additions no I.
II Fire time Remarks I.
I. CD
on
OO 1 15 percent by weight addition product
4 percent by weight Sb _? 0-,
10 percent by weight addition product
4 percent by weight SbgO,
2 percent by weight asbestos I. Solid body burns
completely through at 509834/1 2 15 percent by weight addition product
2 percent by weight SbpO,
2 percent by weight asbestos I. 20 see
20 sec drip burning off
does not drip 029 4th 15 percent by weight addition product
4 percent by weight SbpO,
5 percent by weight of K-titanate fibers I. 8 sec does not drip O.Z. 3 5 15 percent by weight addition product
2 percent by weight Sb pO,
10 weight percent K-titanate fibers 15 sec does not drip O "6 Experiments 1 and 2 are comparative experiments. 10 sec does not drip

Claims (6)

Claims Flame-retardant, reinforced thermoplastic molding compositions based on linear saturated polyesters comprising • A) 10 to 60 percent by weight glass fibers with a thickness of more than 5 / um, B) -5 to 30 percent by weight of a cycloaliphatic chlorine compound, C) 0.5 to 10 percent by weight of a metal oxide of main group V of the periodic table and D) 0.5 to 15 percent by weight of another fibrous Additive less than 5 µm thick. 2. Flammwldrige, reinforced molding compositions according to claim 1, characterized in that polybutylene terephthalate is used as the polyester. 3. Flame-retardant, reinforced molding compositions according to claim 1, characterized in that addition products of hexachlorocyclopentadiene with olefins are used as chlorine compounds. 4. Flame-retardant, reinforced molding compositions according to claim 1, characterized in that antimony trioxide is used as the metal oxide. 5. Flame-retardant, reinforced molding compositions according to claim 1, characterized in that chrysotile asbestos is used as the fibrous additive, 6. Flame-retardant, reinforced molding compositions according to claim 1, characterized in that potassium titanate single crystals are used as the fibrous additive. BASF Aktiengesellschaft 50983A / 102 9