POLYOLEFIN COMPOSITION PROVIDING MARKING BY FLUORESCENCE

Abstract

The present invention is directed to a polyolefin composition comprising carbon black which shows fluorescence when irradiated with UV light. The polyolefin composition of the present invention comprises a polyolefin, carbon black in an amount of 0.25 to 1.0 wt %, an optical brightener in an amount of 0.001 to 0.1 wt %, and a UV agent. The present invention is further directed to a molded article comprising the polyolefin composition of the present invention. The present invention is further directed to a wire or cable comprising an outer layer comprising the polyolefin composition of the present invention. Finally, the present invention is directed to a method for detection of a polyolefin composition by UV light and to a method for detection of a molded article or a wire or cable by UV light.

Claims

1. A polyolefin composition comprising (A) a polyolefin, (B) carbon black in an amount of 0.25 to 1.0 wt % based on the weight of the polyolefin composition, (C) an optical brightener in an amount of 0.001 to 0.1 wt % based on the weight of the polyolefin composition, and (D) a UV agent.

2. The polyolefin composition according to claim 1, wherein the polyolefin is selected from the group consisting of an ethylene homopolymer, an ethylene copolymer, a propylene homopolymer, a propylene copolymer, a blend of an ethylene homopolymer and an ethylene copolymer, and a blend of a propylene homopolymer and a propylene copolymer.

3. The polyolefin composition according to claim 1, wherein the ethylene copolymer is a copolymer of ethylene and a C.sub.3-C.sub.12-alpha-olefin.

4. The polyolefin composition according to claim 1, wherein the propylene copolymer is a copolymer of propylene and ethylene and/or a C.sub.4-C.sub.12-alpha-olefin.

5. The polyolefin composition according to claim 1, wherein the polyolefin is high density polyethylene (HDPE).

6. The polyolefin composition according to claim 1, wherein the polyolefin is polypropylene.

7. The polyolefin composition according to claim 1, wherein the amount of carbon black is 0.25-0.75 wt %, preferably 0.25-0.5 wt %, based on the weight of the polyolefin composition.

8. The polyolefin composition according to claim 1, wherein the amount of the optical brightener is 0.001 to 0.05 wt %, preferably 0.003 to 0.03 wt %, based on the weight of the polyolefin composition.

9. The polyolefin composition according to claim 1, wherein the optical brightener is 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole).

10. The polyolefin composition according to claim 1, wherein the amount of the UV agent is 0.1 to 1.0 wt % based on the weight of the polyolefin composition.

11. A molded article comprising, preferably consisting of, a polyolefin composition according to claim 1.

12. The molded article according to claim 11, wherein the article is an outer layer of a cable.

13. A cable comprising an outer layer comprising, preferably consisting of, the polyolefin composition according to claim 1.

14. A method for detection of a polyolefin composition by UV light comprising the following steps providing a polyolefin composition according to claim 1, irradiating the polyolefin composition with UV light, detecting fluorescence emitted from the polyolefin composition.

15. A method for detection of a molded article or a cable by UV light comprising the following steps providing a molded article or a cable according to claim 11, irradiating the molded article or the cable with UV light, detecting fluorescence emitted from the molded article or the cable.

16. A method for detection of a molded article or a cable by UV light comprising the following steps providing a molded article or a cable according to claim 13, irradiating the molded article or the cable with UV light, detecting fluorescence emitted from the molded article or the cable.

Description

EXAMPLES

1. Definitions/Measuring Methods

[0064] The following definitions of terms and determination methods apply for the above general description of the invention as well as to the below examples unless otherwise defined.

Density

[0065] Density is measured according to ISO 1183-1—method A (2004). Sample preparation is done by compression moulding in accordance with ISO 1872-2:2007.

Flexural Modulus

[0066] Flexural modulus was determined according to ISO 178:2010/Amd.1:2013.

Melt Flow Rate Melt flow rate MFR.sub.2 of polyethylene was determined according to ISO 1133 at 190° C. under a load of 2.16 kg. Melt flow rate MFR.sub.2 of polypropylene was determined according to ISO 1133 at 230° C. under a load of 2.16 kg.

2. Examples

[0067] The following materials and compounds are used in the Examples.

TABLE-US-00001 PE1 poly(ethylene-co-(1-butene)) copolymer having a density of 963 kg/m.sup.3, an MFR.sub.2 of 12 g/10 min, mixed with 39 wt % of carbon black (CB) PE2 bimodal high density polyethylene (HDPE) having a density of 944 kg/m.sup.3, an MFR.sub.2 of 1.7 g/10 min, a flexural modulus of 850 MPa, commercially available as Borstar HE6068 from Borealis AG Optical 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole), brightener commercially available as Tinopal OB CO from BASF SE UV agent Tinuvin 783 FDL commercially available from BASF SE Antioxidant Irganox B225 commercially available from BASF SE Antistatic calcium stearate commercially available as Ceasit SW from agent Baerlocher GmbH

[0068] PE2 is used as base resin and contains already 0.2 wt % of the antioxidant, 0.15 wt % of the antistatic agent and 0.3 wt % of the UV agent.

[0069] Three samples were prepared using PE1 as the carbon black masterbatch (MB), wherein PE1 was compounded with the base resin PE2 in an amount such that the amount of carbon black in the final composition is 0.5 wt % for each of the three samples (see Table 1). In the sample of the comparative example CE1 no optical brightener is added. In the samples of the inventive examples IE1 and 1E2 optical brightener is added.

[0070] Compounding was implemented on ZSK 18 MEGAlab laboratory twin screw extruder under the following conditions: speed 200 rpm; melt temperature 175-190° C.; pressure 45-50 bar; output 5 kg/h. Plaques of size 150×80×3 mm were produced from the resulting composition using injection moulding on Engel ES 700H/80V/700H/250 3K machine under following conditions: injection speed 11 mm/s; injection time 3.4 sec; switching pressure 66 bar; holding time during backpressure 15 sec; cooling time 20 sec; cycle time 45 sec; melt temperature 150° C.; mould temperature 50° C.

TABLE-US-00002 TABLE 1 Compositions of examples wt % CE1 IE1 IE2 Constituents Sample 1 Sample 2 Sample 4 PE2 98.75 98.74 98.745 PE1 1.25 1.25 1.25 Optical brightener — 0.01 0.005 UV agent + + + Antioxidant + + + Antistatic agent + + + “+” indicates the presence of these compounds in PE2

[0071] Laser marking was carried out using Laser machine, “SpeedMarker 700, 20 W Fiber laser”. For marking, a frequency range of 20-100 kHz and a power varying between 5-70% of 20 W was used. Speed was kept constant at 2000 mm/s.

[0072] FIG. 1 shows the laser printed samples as indicated in Table 1 above, wherein these samples are irradiated with UV light, here 250-400 nm.

[0073] Each square represents a combination of frequency to power of the ranges indicated above.

[0074] The laser printed samples were irradiated with UV light (wavelength 250-400 nm). As can be seen from FIG. 1, the inventive samples containing the optical brightener show fluorescence when irradiated with UV light.