DE1038277B - Process for the production of uniformly black molding compounds from polymethylene terephthalates and carbon black - Google Patents

Description

GERMAN

The invention relates to the production of uniformly black molding compositions on the basis high polymer polymethylene terephthalates.

It has been proposed to prepare black high polymer polymethylene terephthalates by one carbon black of the mixture of the starting materials forming the polyester or one having a low molecular weight having, product made from these or the molten polyester itself is added. Shaped articles such as threads, fibers, yarns, films and the like made from black polyesters produced by this method, however, show under certain exposure conditions a brown tint.

It has also been proposed to counteract this brown tint by using certain blue pigments in addition to carbon black, e.g. B. phthalocyanine dyes incorporated into the polymethylene terephthalates, whereby polymeric masses of uniformly deep black color can be obtained. Since these pigments covering a brown tint have a certain degrading effect on the high-polymer terephthalates, only limited amounts can be used ¹ , which means that in many cases the desired effect cannot be achieved to the full extent.

It is also known to use antimony compounds as catalysts for the polycondensation of bis (hydroxyalkyl) terephthalates to be used in the production of high polymer polymethylene terephthalates.

It has now been found that when using larger amounts of antimony compound than they are used for conversion the bis (oj-hydroxy-n-alkyl) -terephthalate used these have little or no degradation effect on the resulting polyester, while at the same time by the addition of these increased amounts of antimony compounds the tendency it is encountered that black polyesters appear brown under certain exposure conditions.

According to the invention there is thus a process for the production of uniformly black molding compositions Proposed from polymethylene terephthalates and carbon black, this process being characterized is that antimony oxide is used as a color shade preventive agent in amounts of at least 0.05% antimony, based on the polyester, is used.

In the production of high-polymer polymethylene terephthalates, a common procedure is that first a glycol of the general formula HO- (CH ₂ ) "OH, where η is an integer greater than 1, but not greater than 10, with a low Molecular weight functional derivative of terephthalic acid, process for preparation
of uniformly black molding compounds made from polymethylene terephthalates and carbon black

Applicant:

Imperial Chemical Industries Limited,
London

Representative: Dipl.-Ing. A. Bohr, Munich 5,
Dr.-Ing. H. Fincke, Berlin-Lichterfelde, Drakestr. 51,
and Dipl.-Ing. H. Bohr, Munich 5, patent attorneys

Claimed priority:
Great Britain October 14, 1955 and September 17, 1956

Norman Fletcher and Norman Standring,

Harrogate, Yorkshire (UK),

have been named as inventors

such as a dialkyl terephthalate, is implemented. The one between these two raw materials occurring transesterification leads to the formation of a bis (co-hydroxy-n-alkyl) -terephthalate. In the In the production of black molding compounds, the carbon black and the antimony oxide are preferred in the The beginning of the polycondensation was added and the bis (i'j-hydroxy-n-alkyl) terephthalate then polycondensed to give a high polymer polymethylene terephthalate.

However, it is not necessary to add the carbon black and the antimony oxide and possibly other additives to be added in this way, but they can also be incorporated into the high polymer polymethylene terephthalates when the polyesters formed are in the molten state or even too any other time during implementation. The carbon black and / or additives can be incorporated be by intimately mixing them directly, or by having them in the form of a dispersion or Solution, e.g. B. in a glycol, or in any other known manner.

The process according to the invention can of course also be used with the addition known per se of a blue pigment, the amount of blue pigment to be added depends on to what extent the high polymer polymethylene

809 600/499 ¹

Claims (4)

terephthalate are degraded. This can be determined by simple experiments by z. B. the intrinsic viscosity of the polyesters that have been produced with and without the addition of the blue pigment is determined. In general, it is advisable to add less than 1% of blue pigment, based on the polyester. In this way it is avoided that an excessive degradation of the same occurs. Any blue pigment which can be appropriately incorporated under the working conditions encountered in the polycondensation of the bis (w-hydroxy-nalkyl) terephthalate or in the melting of the polyester can be used as the blue pigment for this embodiment of the invention. Phthalocyanine pigments are particularly suitable because they are not changed when exposed to higher temperatures. The invention is explained in more detail in the following example. Parts and percentages are based on weight. Example 17.78 parts of fine carbon black are dispersed in 1240 parts by weight of ethylene glycol with the aid of a colloid mill. The glycol containing the pigment is heated with 1552 parts of dimethyl terephthalate, 1.552 parts of calcium acetate and 1.552 parts of antimony oxide until the theoretical amount by weight of methanol required to complete the transesterification has been developed. The fractionation column is then switched off, the temperature is increased to 275 ° C., the pressure is reduced to less than 1 mm of mercury and the polycondensation is carried out in such a way that the mass is heated at this pressure for 1 hour. The resulting black polymer has an intrinsic viscosity of 0.67 and a softening point of 260 ° C. Filaments made from this product by melt spinning have a good black color. For comparison, this procedure was repeated, but using only 0.310 parts of antimony oxide instead of 1.552 parts. The polymer obtained has the same intrinsic viscosity and the same softening point, but the threads produced therefrom have a slight brown sheen. P A T E N T Λ X S P R Γ C. H E: 1. Process for the production of uniformly black molding compositions from polymethylene terephthalates and carbon black, characterized in that the color shading preventive agent Antimony oxide is used in amounts of at least 0.05% antimony, based on the polyester. 2. Embodiment according to claim 1, characterized in that there is also a blue one Pigment used. 3. Embodiment according to claim 2, characterized in that there is a blue pigment Phthalocyanine used. 4. Embodiment according to claim 1 to 3, characterized in that the dyeing and Stabilization of the polymethylene terephthalate during the polycondensation of the polyester performs. Considered publications:
Patent Specification No. 2988 of the Office for Inventions and Patents in the Soviet Zone of Occupation in Germany; German patent application F 7732 IVc / 29 b (announced on July 16, 1953); Fischer, "Point and Varnish Technology," New York, 1948, p. 89. © 809 600/499 9.58