PROTECTIVE COVER FOR A 5G WIRELESS TELECOMMUNICATIONS DEVICE AND METHODS FOR REDUCING SIGNAL ATTENUATION USING THE SAME

Abstract

The present invention relates to a protective cover for a 5G wireless telecommunications device and, in particular, its use in a method of reducing signal attenuation experienced by a 5G wireless communications device.

Claims

1-21. (canceled)

22. A method of reducing signal attenuation by an impact protective cover for a 5G wireless communications device, said method comprising providing a protective cover, the cover being formed from a thermoplastic elastomer resin composition having hollow microspheres dispersed therein.

23. A method according to claim 22, wherein the hollow glass spheres are added to the thermoplastic elastomer resin composition in an amount of from 1 to 35% based on the weight of the thermoplastic elastomer resin composition.

24. A method according to claim 22, wherein the average diameter of the hollow microspheres is from 1 to 600 microns.

25. A method according to claim 22, wherein the hollow microspheres have a unimodal particle size distribution.

26. A method according to claim 22, wherein the hollow microspheres have a multimodal particle size distribution.

27. A method according to claim 22, wherein the hollow microspheres are formed of glass, ceramic, clay or polymer.

28. A method according to claim 22, wherein the thermoplastic elastomer is selected from a thermoplastic polyurethane polymer, an acrylic-based polymer and a polyolefin multiblock copolymer.

29. A method according to claim 28, wherein the thermoplastic polyurethane polymer is an aromatic ether based polyurethane polymer, the acrylic-based polymer is a (meth)acrylate di- or tri-block copolymer and/or the polyolefin multiblock copolymer is a polystyrene-polyolefin multiblock copolymer.

30. A method according to claim 22, wherein one or more additives is incorporated into the thermoplastic elastomer resin composition to improve abrasion-resistance, scratch resistance and/or dye-transfer resistance of the protective cover formed therefrom.

31. A method according to claim 30, wherein the one or more additives includes silicone gum.

32. A method according to claim 22, wherein forming the protective cover comprises dispersing the hollow glass spheres in the thermoplastic elastomer resin composition and moulding to form the protective cover.

33. A method according to claim 22, further comprising the step of securing the protective cover to a wireless communications device for protecting the device from impact.

34. A method according to claim 22, wherein the wireless communications device is a mobile telecommunication device.

35. A 5G wireless telecommunications device impact protective cover, said protective cover comprising a thermoplastic elastomer composition having hollow glass microspheres dispersed therein.

36. A protective cover according to claim 35, wherein the thermoplastic elastomer is selected from a thermoplastic polyurethane polymer, an acrylic-based polymer and a polyolefin multiblock copolymer.

37. A protective cover according to claim 36, wherein the thermoplastic polyurethane polymer is a an aromatic ether based polyurethane polymer, the acrylic-based polymer is a (meth)acrylate di- or tri-block copolymer and/or the polyolefin-multiblock copolymer is a polystyrene-polyolefin multiblock copolymer.

38. A protective cover according to claim 35, wherein the protective cover has at least one of the following: i) a tensile strength of from 2.0 to 8.0 MPa, as measured by ASTM D412; ii) a tensile modulus of from 5.0 to 20 MPa, as measured by ASTM D412; iii) a flexural strength of from 1.0 to 5.0 MPa, as measured by ASTM D790; iv) a flexural modulus of from 30 to 150 MPa, as measured by ASTM D790; v) a dielectric constant which is less than 2.90 at a frequency of 1.8 GHz; vi) a dielectric constant which is less than 2.70 at a frequency of 10.2 GHz; vii) a dielectric constant which is less than 2.50 at a frequency of 28 GHz and 39 GHz; viii) a power attenuation which is less than 45 dB/m at a frequency of 1.8 GHz; and ix) a power attenuation which is less than 145 dB/m at a frequency of 10.2 GHz.

Description

EXAMPLES

Example 1

[0065] Thermoplastic elastomer resin blends were prepared having the compositions specified in Table 1 below, each blend comprising various amounts of poly(methyl methacrylate)-b-poly(n-butyl acrylate)-b-poly(methyl methacrylate) triblock copolymer, PMMA-b-PnBA-b-PMMA, (KURARITY LA2250 from Kuraray), additional acrylic based thermoplastic elastomer, hollow glass microspheres (3M Glass Bubbles iM16K, having an average diameter of 20 microns) and an optional silicone gum based additive (MB50-002 from Dow Corning).

TABLE-US-00001 TABLE 1 Blend 1 Blend 2 Blend 3 Blend 4 PMMA-b-PnBA-b-PMMA 45 40 38.5 43.5 Other acrylic based 45 40 38.5 43.5 polymer Hollow Glass 10 20 20 10 Microspheres Silicone gum 1 3 3 Total % 100.00 100.00 100.00 100.00

[0066] The polymer resin for each of Blends 1 to 4 was weighed and 0.5% semtol oil was added to facilitate dispersion of the microspheres (by sticking to the pellets of thermoplastic elastomer). Semtoil oil has a sufficiently low boiling point such that it may be subsequently removed from the composition by action of a vacuum pump. 10 Kg each of Blends 1 to 4 were subsequently compounded on a lab-line 24 mm twin-screw extruder before being pelletized to produce pellets.

Example 2

[0067] Thermoplastic elastomer resin blends were prepared having the compositions specified in Table 2 below, each blend comprising various amounts of a polyether based aromatic polyurethane (Estane 58887, Lubrizol), hollow glass microspheres (3M Glass Bubbles iM16K, having an average diameter of 20 microns) and an optional silicone gum based additive (Genioplast Pellet S from Wacker).

TABLE-US-00002 TABLE 2 Blend 5 Blend 6 Estane 58887 90 87 Hollow glass 10 10 spheres Silicone gum 3 Total % 100.00 100.00

[0068] Blends 5 and 6 were mixed on a Banbury Internal Mixer with tangential rotors. The volume size of the mixer was 1.57 L, batch sizes were approximately 1.3 kg to as to fill the cavity. The resins of Blends 5 and 6 were added to the mixer and the speed of the rotators was set to 240 RPM for several minutes before the microspheres were added once the polymer was molten, at approximately 180 C. After mixing, the speed was dropped to 50 RPM for a several minutes, before the mixer was cooled to 137 C. The material was then in each case transferred to a granulator to yield pellets.

Example 3 (Comparative)

[0069] Thermoplastic elastomer resin blends were prepared having the compositions specified in Table 3 below, each blend comprising various amounts of: i) an acrylic based thermoplastic elastomer composition comprising poly(methyl methacrylate)-b-poly(n-butyl acrylate)-b-poly(methyl methacrylate) triblock copolymer, PMMA-b-PnBA-b-PMMA (KURARITY LA2270 from Kuraray) in combination with an amorphous silica component; ii) an acrylic based thermoplastic elastomer corresponding to poly(methyl methacrylate)-b-poly(n-butyl acrylate)-b-poly(methyl methacrylate) triblock copolymer, PMMA-b-PnBA-b-PMMA, (KURARITY LA2250 from Kuraray), iii) a further acrylic based thermoplastic elastomer; an optional synthetic, hydrophilic amorphous silica additive (HDK N20 from Wacker); iv) a polycarbonate thermoplastic polymer (SABIC Lexan ML3290 PC); v) a polyester polyurethane elastomer (BASF Elastollan C-85A); and/or vi) a polycarbonate thermoplastic polymer (Covestro Makrolon 2805).

TABLE-US-00003 TABLE 3 Blend 7 Blend 8 Blend 9 Blend 10 Blend 11 PMMA-b-PnBA-b-PMMA 50 (KURARITY LA2250) PMMA-b-PnBA-b-PMMA 100 (KURARITY LA2270) + amorphous silica Other acrylic based 49 polymer Amorphous silica additive 1 Polycarbonate 100 thermoplastic (SABIC Lexan ML3290 PC) Polyester polyurethane 100 elastomer (BASF Elastollan C-85A) Polycarbonate 100 thermoplastic (Covestro Makrolone 2805) Total % 100.00 100.00 100.00 100.00 100.00

[0070] Pellets of the polymer resins for each of Blends 7 to 11 were prepared substantially by the method of Example 1, except that the amorphous silica additive, where present, was dusted on to the pellets prior to compounding in the twin-screw extruder and no hollow glass spheres were added at any stage.

Example 4

[0071] The pellets formed from Blends 1 to 3, 5 to 8 and 10 of Examples 1 to 3 were injection moulded into 2 mm phone cover test pieces which were assessed for their impact strength based on a peak transmitted force test in which a corner of the test dummy impacted the 2 mm phone cover test pieces 3 times at sequentially greater drop heights onto an anvil. The transmitted force is measured by piezoelectric load cell beneath the anvil and average values recorded at each drop height. The lower the measured peak transmitted force, the greater the impact protection provided. The results of the peak transmitted force tests are show in Table 4 below.

TABLE-US-00004 TABLE 4 PTF (kN) PTF (kN) PTF (kN) Blend (1 m Drop Height) (1.6 m Drop Height) (3 m Drop Height) 1 1.95 2.54 3.47 2 2.08 2.68 3.42 3 2.02 2.60 3.34 5 1.91 2.53 3.36 6 1.92 2.55 3.36 7 1.98 2.72 3.57 8 1.99 2.65 3.58 10 1.91 2.81 3.85

[0072] The results of Table 4 demonstrate that the presence of hollow microspheres has little or no effect on the impact strength of the test piece, as is particularly evident from the comparison of the results of Blends 1 to 3, 5 and 6 with comparative Blends 7 and 8, where very little difference in performance is noticeable. In fact, Blends 5 and 6, have lower peak transmitted force at each drop height than for all of the comparative examples indicating a minor improvement in impact strength.

Example 5

[0073] The pellets formed from Blends 1 to 11 from the above Examples were injection moulded into 1 and 2 mm plaques and their absolute permittivity () tested using a Split-Post Dielectric Resonator (for 1.8 and 10.2 GHz frequencies) or using an MCK (Material Characterization Kit) machine, available for example from Swissto12 (for 50 GHz frequency), the results of which are shown in Table 5 below.

TABLE-US-00005 TABLE 5 Permittivity () Permittivity () Permittivity () Blend (1.8 GHz, 2 mm) (10.2 GHz, 1 mm) (50 GHz, 2 mm) 1 2.60 2.52 2 2.56 2.50 3 2.48 2.42 4 2.60 2.53 2.47 5 2.92 2.72 6 2.89 2.70 2.58 7 2.74 2.64 2.59 8 2.75 2.64 9 2.79 2.75 2.77 10 3.43 3.08 2.94 11 2.80 2.67 2.80
The lower the value of permittivity (), the lower the ability of the material to absorb electromagnetic energy and, as a result, the lower the propensity to attenuate an radiofrequency signal of a communications network. As can be seen above, increasing the proportion of hollow glass spheres in the composition across Blends 1, 2 and 3 (10%, 20% and 23% respectively) leads to a corresponding decrease in permittivity (). At much higher frequency (50 GHz), the TPU based inventive Blend 4 shows substantially lower permittivity () (2.47) in comparison to comparative TPU based Blend 10 (2.94). This highlights the particular benefit of the invention in lowering absorption of electromagnetic energy of high frequency, including frequencies of an order which characterise the high frequency bands of the 5G network (i.e. above 24 GHz).

Example 6

[0074] Test pieces formed from Blends 1, 3 and 6 according to the invention from the above Examples were tested for tensile strength (ASTM D412), elongation at break (EAB) (ASTM D412), Young Modulus (ASTM D412), and Flex modulus (ASTM D790), averaged results of which are provided in Table 6 below.

TABLE-US-00006 TABLE 6 Tensile Elongation Flex Modulus Maximum at Break Young Maximum Flex Tensile Stress (EAB) Modulus Stress Modulus Blend (MPa) (%) (MPa) (MPa) (MPa) 1 3.26 309 5.7 1.49 42.7 3 2.05 168 14.8 2.57 98.2 6 5.27 629 12.4 2.8 80.1