Field of the Invention

The invention relates to co-extruded multi-layer polypropylene plastic pipes for use in wastewater drainage stacks.

Background of the Invention

Polypropylene plastic pipes for use in wastewater drainage stacks are required to meet technical standards including inter alia:

EN 1451-1:2017 (E) - Plastics piping systems for soil and waste discharge (low and high temperature) within the building structure - Polypropylene (PP) - Part 1: Specifications for pipes, fittings and the system, the contents of which are incorporated reference by reference. EN 1451- 1:2017 (E) published November 2017 is directed towards single layer polypropylene plastic pipes.

EN 13476-2:2018 (E) - Plastics piping systems for non- pressure underground drainage and sewerage - Structured-wall piping systems of unplasticized poly (vinyl chloride) (PVC-U), polypropylene (PP) and polyethylene (PE) -- Part 2: Specifications for pipes and fittings with smooth internal and profiled external surface and the system, Type A, the contents of which are incorporated herein by reference. EN 13476-2:2018 (E) published April 2018 is directed towards multi-layer plastic pipes.

EN 1451-1:2017 (E) hereinafter abbreviated to the EN 1451 standard and EN 13476-2:2018 (E) hereinafter referred to as the EN 13476 standard and are available from CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels www.cencenelec.eu. EN 1451 and EN 13476 refer to standard tests for testing a wide range of pipe specifications but omit a soundproofing test since soundproofing is regulated with regards to a building structure. Exemplary soundproofing technical standards for a building structure include:

Israel Standard IS 1004 Part 4: Acoustics in Residential Buildings: sound Pressure Level from Sanitation Installations: Requirements and Test Methods commercially available from: https://www. sii.org.il/he/%D7 %93 %D7 % A4%D7 %99- %D7%9C%D7%95%D7%91%D7%99/%D7%9B%D7%9C%D7%9C%D7%9 9/%D7%AA%D7%A7%D7%99%D7%A0%D7%94/%D7%93%D7%A3- %D7%AA%D7%A7%D7%9F/?id=b5a81950-4486-4227-a0e3-7584a96a38ec

DIN 4109 Sound Insulation in Buildings commercially available from https://www.en-standard.eu/din-4109- 1 -schallschutz-im-hochbau-teil- 1 - mindestanforderungen/

DIN EN 14366:2004+Al:2019 German version: Laboratory measurement of noise from waste water installations commercially available from https://www.techstreet.com/standards/din-en- 14366?product_id=2100550

To assist a building structure to meet soundproofing requirements, it is known to add a mineral compound to a base plastic material to form a mineral compound plastic mixture which has a greater density compared to the base plastic material thereby resulting in a heavier pipe per meter than without the mineral compound. Moreover, it is also known that increasing a mineral compound's wt% leads to increased density and soundproofing.

Applicants manufacture and supply soundproofing co-extruded multilayer polypropylene plastic pipes under the trade name ULTRA-SILENT. Such polypropylene plastic pipes have a triple layer construction including: Black polypropylene outermost layer for impact resistance and UV protection. Mineral reinforced polypropylene intermediate layer for high mechanical resistance and sound reflection for effecting soundproofing. And white polypropylene innermost layer for flow performance and high definition contrast for visual inspection. The black outermost layer and the white innermost layer are typically constituted by similar polypropylene material combined with different colored pigments. There is a need for soundproofing polypropylene plastic pipes for use in wastewater drainage stacks.

Summary of the Invention

The present invention is directed toward soundproofing co-extruded multi-layer polypropylene plastic pipes for use in wastewater drainage stacks and a method of manufacture therefor. The co-extruded multi-layer polypropylene plastic pipes have a concentric construction including a soundproofing intermediate composite between a conventional polypropylene outermost layer and a conventional polypropylene innermost layer. The soundproofing intermediate composite includes a synergistic soundproofing combination of at least one high density layer for sound reflection and at least one foamed polypropylene layer for sound absorption. The high density layer has a thickness THD and a density of between about 1.0 g/cm ³ and about 2.5 g/cm ³ . The foamed polypropylene layer has a thickness TF > 2 THD and a density of between about 0.4 g/cm ³ and about 0.85 g/cm ³ . The soundproofing co-extruded multi-layer polypropylene plastic pipes of the present invention can be designed to have at least equivalent soundproofing capability as a conventional soundproofing polypropylene plastic pipe while being lighter per meter by virtue of the use of foamed polypropylene which also reduces carbon footprint. Reducing weight per meter facilitates transportation to a building structure, handling at a building structure, and the like.

The soundproofing co-extruded multi-layer polypropylene plastic pipes of the present invention can be manufactured to meet presently applicable technical standards EN 1451-1:2017 (E) and EN 13476-2:2018 (E). These technical standards can be superseded in time. The teachings of the present invention can be equally applied to future technical standards relating to plastics piping systems for use in wastewater drainage stacks.

The soundproofing co-extruded multi-layer polypropylene plastic pipes of the present invention can be manufactured by a conventional co-extrusion method of manufacture. Brief Description of Drawings

In order to understand the invention and to see how it can be carried out in practice, preferred embodiments will now be described, by way of nonlimiting examples only, with reference to the accompanying drawings in which similar parts are likewise numbered, and in which:

Fig. 1 is a table corresponding to EN 1451-1:2017 (E) page 17's Table 4 - Wall Thickness (metric series);

Fig. 2 is a table corresponding to EN 13476-2:2018 (E) page 21's Table 6 - Nominal sizes, minimum mean inside diameters, thickness of inside layers and socket length;

Fig. 3 is a transverse cross section of a soundproofing co-extruded multi-layer polypropylene plastic pipe commercially available from the Applicant under the trademark ULTRA-SILENT ;

Fig. 4 is an enlarged view of Figure 3 pipe's encircled area denoted IV;

Fig. 5 is a table showing a legend of Figure 3 pipe's layers, and their material description, thickness and density;

Fig. 6 is a transverse cross section of a soundproofing co-extruded multi-layer polypropylene plastic pipe in accordance with one embodiment of the present invention;

Fig. 7 is an enlarged view of Figure 6 pipe's encircled area denoted VII;

Fig. 8 is a table showing a legend of Figure 6 pipe's layers, their material description, thickness and density;

Fig. 9 is a transverse cross section of a soundproofing co-extruded multi-layer polypropylene plastic pipe in accordance with another embodiment of the present invention;

Fig. 10 is an enlarged view of Figure 9 pipe's encircled area denoted X;

Fig. 11 is a table showing a legend of Figure 9 pipe's layers, their material description, thicknesses and density;

Fig. 12 is a transverse cross section of a soundproofing co-extruded multi-layer polypropylene plastic pipe in accordance with yet another embodiment of the present invention; Fig. 13 is an enlarged view of Figure 12 pipe's encircled area denoted

XIII;

Fig. 14 is a table showing a legend of Figure 12 pipe's layers, their material description, thicknesses and density;

Fig. 15 is a transverse cross section of a soundproofing co-extruded multi-layer polypropylene plastic pipe in accordance with yet another embodiment of the present invention;

Fig. 16 is an enlarged view of Figure 15 pipe's encircled area denoted XVI; and

Fig. 17 is a table showing a legend of Figure 15 pipe's layers, their material description, thicknesses and density.

Detailed Description of Drawings

Section 1: Technical Standards

The polypropylene plastic pipes of the present invention are compliant to at least one of the aforementioned EN 1451 and EN 13476.

Figure 1 corresponds to the EN 1451:l:2017(E) page 17's Table 4 - Wall Thickness (metric series). The relevant columns for the purposes of the present invention are the middle pipe thickness Pipe series S16 column and the thickest pipe thickness Pipe series S 14 column

Figure 2 corresponds to E13476-2:2018(E) page 21 's Table 6 - Nominal sizes, minimum mean inside diameters, thickness of inside layers and socket length. The relevant columns for the purposes of the present invention are Minimum mean inside diameter 3 ^rd column PP/PE ^{b c} and Minimum wall thickness 1 ^st column Multi-layer e4,min

Section 2: Applicant's ULTRA-SILENT

Figure 3 to Figure 5 refer to Applicant's ULTRA-SILENT co-extruded multi-layer polypropylene plastic pipe 10 for use in wastewater drainage stacks. The pipe is both EN 1451 and EN 13476 compliant. The pipe 10 includes the following three concentric layers: Outermost layer 11 : Black polypropylene for impact resistance and UV protection

Intermediate layer 12: Mineral reinforced polypropylene for high mechanical resistance and soundproofing

Innermost layer 13: White polypropylene for flow performance and high definition contrast for visual inspection

The black polypropylene outermost layer 11 and the white polypropylene innermost layer 13 are similar polypropylene material with different colored pigments. Suitable polypropylene material is Capilene® SE 50E commercially available from Carmel Olefins Ltd, Haifa, Israel www.carmel-olefins.co.il.

The mineral reinforced polypropylene can be manufactured from a mineral compound polypropylene mixture having a density between about 1.0 g/cm ³ and about 2.0 g/cm ³ . Suitable mineral compounds include inter alia Granic 1025 commercially available from Carrer B otters s/n www.granic.es, BC5755PPW commercially available from Tosaf Ltd, www.tosaf.com, and the like.

Section 3: Soundproofing co-extruded multi-layer polypropylene plastic pipes of present invention

Section 3.1 Concentric Layer Construction

Figure 6 to Figure 17 relate to four soundproofing co-extruded multilayer polypropylene plastic pipes 20, 30, 40 and 50 including concentric layers as follows:

Polypropylene outermost layer similar to conventional outermost layer At least one foamed polypropylene layer for soundproofing

At least one high density layer for high mechanical resistance and soundproofing

Polypropylene innermost layer similar to conventional innermost layer Figure 6 to Figure 8 relate to a soundproofing co-extruded multi-layer polypropylene pipe 20 including a polypropylene outermost layer 21, a soundproofing intermediate composite 22, and a polypropylene innermost layer 23. The soundproofing intermediate composite 22 includes a foamed polypropylene layer 24 concentrically encircling a high density layer 26.

Figure 9 to Figure 11 relate to a soundproofing co-extruded multi-layer polypropylene pipe 30 including a polypropylene outermost layer 31, a soundproofing intermediate composite 32, and a polypropylene innermost layer 33. The soundproofing intermediate composite 32 includes a high density layer 34 concentrically encircling a foamed polypropylene layer 36.

Figure 12 to Figure 14 relate to a soundproofing co-extruded multi-layer polypropylene pipe 40 including a polypropylene outermost layer 41, a soundproofing intermediate composite 42, and a polypropylene innermost layer 43. The soundproofing intermediate composite 42 includes a high density layer 44 sandwiched between a pair of foamed polypropylene layers 46 and 47.

Figure 15 to Figure 17 relate to a soundproofing co-extruded multi-layer polypropylene pipe 50 including a polypropylene outermost layer 51, a soundproofing intermediate composite 52, and a polypropylene innermost layer 53. The soundproofing composite layer 52 includes a foamed polypropylene layer 54 sandwiched between a pair of high density layers 56 and 57.

Section 3.2 Pipe wall specifications: pipe wall thickness and layer thickness

EN 1451 compliant and EN 13476 compliant soundproofing polypropylene pipes have different pipe wall specifications depending on their Outer Diameters (ODs).

The soundproofing co-extruded multi-layer polypropylene pipes 20, 30, 40 and 50 are suitable for being manufactured in accordance with EN 1451 middle pipe thickness Pipe series column S 16 and the thickest pipe thickness Pipe series column S 14. The polypropylene outermost layers 21, 31, 41 and 51 have a minimum thickness To of 0.2 mm. The polypropylene innermost layers 23, 33, 43 and 53 have a minimum thickness Ti of 0.2 mm. EN 13476 compliant soundproofing co-extruded multi-layer polypropylene pipes 20, 30, 40 and 50's polypropylene innermost layers 23, 33, 43 and 53 have a minimum thickness of 0.4 mm.

Section 3.3 Layer Material and Density

The foamed polypropylene layers 24, 36, 46, 47 and 54 can be manufactured from polypropylene material and a foaming agent. Suitable foaming agents include inter alia Tracel® PP 2201 FO https://www.tramaco.de/en/products/foaming-agents/chemical-f oaming-agents- for-polyolefin-extrusion.html commercially available from Tramaco GmbH www.tramaco.de. The foamed polypropylene layers 24, 36, 46, 47 and 54 have a density of between about 0.4 g/cm ³ and about 0.85 g/cm ³ .

The high density layers 26, 34, 44, 56 and 57 can be manufactured from one of a mineral compound polypropylene material mixture, a nano particle polypropylene material mixture and a nano particle mineral compound polypropylene material mixture. Suitable commercially available mineral compounds include inter alia Granic 1025 commercially available from Carrer Boters s/n www.granic.es, BC5755PPW commercially available from Tosaf Ltd, www.tosaf.com, and the like. Suitable commercially available nano particles include inter alia Cloisite Nc 93A commercially available from BYK www.byk.com. The high density layers 26, 34, 44, 56 and 57 have a density of between about 1.0 g/cm ³ and about 2.5 g/cm ³ .

Section 3.4 Pipe weight g/m comparison between present invention and ULTRA SILENT pipe having the same 110mm outer diameter (OD) and both EN 1451 S16 compliant

ULTRASILENT Pipe weight: 1,350 g/m to 1,450 g/m

Present invention pipe weight 950 g/m to 1,050 g/m While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications, and other applications of the invention can be made within the scope of the appended claims.