CS219692B1 - Near-infrared low visibility polyamide - Google Patents

Abstract

The invention relates to polyamides intended for special purposes. It aims to reduce the visibility of polyamides, especially green polyamides, in the near infrared region. This is achieved by adding 0.05 to 1.00 wt. % of cadmium sulfide. In addition to this pigment, the polyamide may contain a complementary pigment, which provides a green color. In addition, the polyamide may also contain other pigments, fillers and other plastic additives, which modify its processing and utility properties.

Description

The present invention relates to polyamides with reduced near-infrared visibility. It belongs to a group of materials that are designed for special purposes.

The prior art polyamides colored with conventional pigments and optionally containing fillers and other plastic additives are well visible in the near region of the infrared spectrum, defined by the wavelength range of the electromagnetic wave from 650 to 5000 nm. Visibility in this area is assessed by the spectrosonal criterion, which is defined as 2.98 times the ratio of the polyamide reflectivity at a wavelength of 650 and 750 nm. Normal visibility is characterized by values of the spectrosonal criterion greater than 1.10. Dosial '_; The known green polyamides most often contain chromium trioxide, phthalocyanine derivatives or a mixture of iron oxide and ultramarine as pigments. Such polyamides have a spectrosonal criterion greater than 1.10.

It has now been found that near-infrared visibility in polyamides can be reduced by polyamide containing 0.05 to 1.00 wt. % cadmium sulfide. In addition to this active ingredient, the polyamide may also contain other pigments and / or fillers and / or other plastic additives. For example, to obtain the green polyamide, it is necessary to add a complementary color pigment in an amount of 0.1 to 5.00 wt. %, such as ultramarine, optionally green pigment, calcium stearate, if desired, to refine the shade of titanium dioxide and improve the mechanical and thermal properties of the glass fiber.

Although the use of cadmium sulphide is known in addition to other pigments for obtaining the living polyamide, it has not been known until the time of the invention and therefore its 'decrease in visibility' property in the near region of the infrared spectrum has not been exploited. Therefore, its use for obtaining green polyamide was not known either.

Claims (2)

SUBJECT Polyamide with reduced near-infrared visibility, in particular green, polyamide, optionally containing pigments and / or fillers and / or other plastic additives, characterized by using 0.05 to 1.00 wt. %, preferably 0.30 wt. % cadmium sulfide. Cadmium sulfide containing polyamides have a spectrosonic criterion value of less than 1.10. By reducing visibility in the near infrared region, it is more difficult to observe polyamide objects by scanners operating at near-infrared wavelengths. Therefore, the invention can be advantageously used for those purposes where observation of polyamide articles is not desirable. Example 1 Green polyamide 6, containing 0.3 wt. % cadmium sulphide, 0.7 wt. % ultramarine 0.2 wt. % titanium dioxide, 0.5 wt. % calcium stearate, 30.0 wt. % of glass fiber has a spectrosonal criterion value of 0.85. The green polyamide 6 containing the same is produced in the same manner 0.8 wt. % chromium oxide, 0.2 wt. % titanium dioxide, 0.5 wt. % calcium stearate, 30.0 wt. % of glass fiber has a spectrosonal criterion value of 1.23. Example 2 Green polyamide 6, containing 0.3 wt. % cadmium sulphide, 0.7 wt. % ultramarine 0.2 wt. % titanium dioxide, 1.0 wt. % of calcium stearate, has a spectrosonal criterion value of 0.91. The green polyamide 6 containing the same is produced in the same manner 0.5 wt. % chromium trioxide, 1.0% by weight of titanium dioxide, 1.0 wt. % of calcium stearate has a spectrosonal criterion value of 1.20. INVENTION 2. The polyamide according to claim 1, wherein the cadmium sulphide is 0.10 to 5.00 wt. % of a complementary pigment, preferably ultramarine.