DK9700296U3 - Multilayer pipes - Google Patents

Abstract

A pipe, with a bell preferably formed in place, whose radial rigidity is greater than 4 kN/m<2> for the wall thicknesses given in Table 1, consists of three layers (1, 2, 3). The middle layer (3) consists of a polyolefin, in particular polypropylene, that is reinforced with 25 % to 70 % by weight of a mineral, and is foamed to a density preferably at least 10 % less than the density of a comparable middle layer that is only reinforced in the same proportion. The outer layer (1) and the inner layer (2) consist preferably of the same synthetic material as the middle layer (3). The middle layer is preferably reinforced with talcum or chalk, or a mixture of the two.

Description

DK 97 00296 U3

Multilayer tube

The production relates to a multi-layered pipe, co-extrusioned, optionally with a shaped sleeve, and the middle layer consisting of a polyolefin with pre-filled mineral material.

So far, wastewater disposal pipes, made up of polyolefins, such as polypropylene (PP) or polyethylene (PE), have had the disadvantage of requiring a high consumption of material (wall thickness) to ensure the necessary rigidity, and 10 under load. exhibits a clear long-term deformation. As a result, sewer pipes made of polyolefins with the nominal stiffness (SN) SN4 (4kN / m2) and SN8 (8kN / m2) required are not economical in relation to PVC or voids and contain too much polymer.

Another disadvantage is the manufacture of the molded sleeve on polyolefin (PP and PE) tubes. To date, accurate molding has only been possible when high-cost technical costs were accepted (both for moving cores and for blasting production). In addition, large 20 tolerances were required to adhere to certain values of the long-term creep. The excessive tolerances on the sleeve dimensions and different creep values led to an inaccurate fit with the pipe ends or moldings to be connected. In addition, the heating and cooling times of polyolefin (PP or PE) tubes are relatively high, so that the production rate was limited depending on the thickness of the material and thus also the profitability.

From AT 0 000 643 U1 a three-layer tube is known, the middle layer of which consists of polypropylene, with 25-50 wt% talc added. Due to the high density of the middle layer of this tube (about 1.2 g / cm 2), one has to live with the disadvantage that the tube has high weight at large wall thicknesses, especially when the middle layer is thick.

2 DK 97 00296 U3

The object of the invention is to compensate for the disadvantages of polyolefin (PP or PE) initially described.

In particular, it is an object of the invention to reduce the, in ecologically and economically, high polymer shares in the pipe to less than half of the previously known pipes without impairing the technical properties of the pipe.

This object is achieved with a tube having the features of claim 1.

The subclaims relate to preferred embodiments of the pipe according to the invention.

In one embodiment, the tube according to the invention is a multilayer tube, preferably made by coextrusion. For example, the multilayer tube consists of at least one support layer, preferably the middle layer, of a mineral-filled and foamed polyolefin, in particular polypropylene. For example, the tube has a - especially the thin wall - outer and inner layers.

By means of the production, a pipe in the dimension range DN 100 to DN 1000 of e.g. a polyolefin, especially of PP, could be formed directly on the sleeve by "inline" technique. In the pipe according to the production, the radial pipe stiffness at the minimum thicknesses in the table o is not less than 4 kN / rrr (tested according to ISO / DIS 9969). In the middle layer, a recycled material, a "regenerate" or a "recyclate" can be used. 2. The terms "regenerate" and "recyclate" are used herein to mean: a "regenerate" is a recycled material that is produced as a hernia during production and - without further use - is again fed into the production stream A "recyclate" is a material which is recovered from an already in use product and which is then used for another or similar product.

In the present case, the term "radial tube stiffness" should be equal to 2 with the term "peak stiffness" (Scheitelsteifigkeit) 3 DK 97 00296 U3 (SN). SN is the stiffness that counteracts a "top deformation" (Scheitelde deformation) according to ISO / DIS 9969, which results from a load on the top of the pipe. The peak stiffness is in contrast to the axial tube stiffness. These different designations are due to the way one considers the influence of loads and of the superimposed layers and the type of pipe reaction (bending, hole formation, cracking, etc.) due to these loads. Radial load causes deformation of the pipe cross section, e.g. bumps, and axial load causes deformation of the longitudinal axis of the tube, e.g. bending.

The increase of. according to the manufacture, the pipe stiffness or elastic modulus is preferably obtained by means of mineral-filled foamed layers.

The foamed layer, which may be the middle layer of a three-layered tube, can be filled with talc, chalk or similar mineral material, or with a mixture of several mineral materials.

It is preferred, according to the invention, that the foamed (middle) layer consists of polypropylene or polyethylene. The layers of the pipe according to the production can also consist of the same plastic.

An outer layer provided on the foamed middle layer can have a thickness of 0.2-2.0 mm in a pipe according to the production. An inner layer provided on the foamed middle layer may have a thickness of 0.2-3.0 mm. The inner layer may, for example, consist of a polypropylene copolymer.

The pipe according to the invention can have a radial pipe stiffness of more than 4 kN / m2.

An embodiment of a pipe according to the invention is shown in section in FIG. 1. Although the embodiment shown in the drawing is a three-layer pipe, the production is not limited to such a pipe. There may be more or less than three layers, e.g. more than two non-op s comb the layers and / or several foam layers.

To ensure the optimum ratio of sufficient impact toughness and high stiffness, a mixture consisting of 25-70 parts by weight of talc or 25-70 parts by weight of chalk or a mixture of chalk and talc in the ratio of approx. 1: 1 as a filler in a polyolefin which is, for example, PP (PP = polypropylene) or a PP homo- or copolymer, or a mixture thereof.

By the mineral reinforcement and a uniform mineral distribution, a stiffness of the middle layer material is obtained, where the E-module is approx. 2,000-3,400 N / mm 2. The mineral filling has the disadvantage that the weight of the pipe increases substantially. The density of, for example, a 35 parts talc-filled PP (center) layer is 1.18-1.2 g / cm 3. By means of a propellant, the mineral-filled (middle) layer is foamed by an extrusion process, and the density is preferably reduced by at least 10%, for example from the original density of 1.2 g / cm3 to at most 1.08 g / cm3, preferably 0 , 8-0.9 g / cm 3. However, the density can also be reduced down to 0.2 g / cm3 or even less.

This material is the supporting material in the (middle) layer of the pipe according to the invention. Due to the large mineral filling in the polyolefin material of the (middle) layer, for example the polypropylene (PP), a smaller enthalpy and a better heat conduction are also advantageous, which is advantageous for faster and more uniform heating and cooling in connection with the subsequent molding of the sleeve. The uniformly distributed thickness of material in all the layers of pipes and the uniform distribution of minerals in the material, e.g. the middle layer, also ensures a controlled creep of the tube and sleeve.

The outer layer and inner layer of the tube contribute to the required strength in relation to internal pressure and impact resistance at lower temperatures. According to the invention, the inner layer and the outer layer may consist of a polyolefin, e.g. PP-copolymer.

To date, pipes made of polyolefin have mostly been made with only one layer, which has led to problems in edge fibers with differences in crystallinity, since crystallinity in the various regions has not been precisely defined or manufactured and even varies in irregular regions. during manufacture.

However, since crystallinity is a very significant factor for the strength of a tube with respect to the internal pressure over a short and long time and with respect to impact toughness, it is desirable for the optimization of this mechanical property to make the degree of crystallization, especially in the inner layer, so homogeneous. and as high as possible. The more thin-walled a tube layer is with respect to the surface of the tube, the better the crystallinity can be controlled during the cooling process, and the easier it is to be able to keep the degree of crystallization constant (at a given value) over the length and circumference of the tube.

This is made possible with the pipe according to the production, since according to the production at least one layer of reinforced and foamed mineral materials represents the greatest part of the carrying capacity of the pipe. In this way it is possible to keep the inner layer and the outer layer thin and precisely match them to the requirements described just before. Further, to increase the strength of the tube, polypropylene with a partial mesh structure may be used, optionally in a mixture with polypropylene without mesh structure.

The thickness of the goods is adapted to the mechanical / chemical requirements and is shown in Table 1 together with the entire wall thickness in connection with different dimensions.

Table 1: 30 Pipe dimensions and wall thicknesses for three-layer pipes with a peak stiffness of 4 kN / m2 (SN 4) 6 DK 97 00296 U3 DN dl (mm) si min (mm) cm min (mm) sa min (mm) s sam min (mm) s real (mm) 110 110.00 0.60 2.30 0.50 3.40 3.70 125 125.00 0.60 2.70 0.50 3.80 4.20 160 160, 00 0.60 3.60 0.50 4.70 5.30 200 200.00 0.60 4.70 0.50 5.80 6.60 250 250.00 0, 70 5.90 0.60 7, 20 8.30 315 315.00 0.80 7.50 0.70 9.00 10.40 400 400.00 1.00 9.50 0.80 11.30 13.20 500 500.00 1.10 12 , 00 0.90 14.00 16.50 600 600.00 1.20 15.30 1.00 17.50 20.80 7 DK 97 00296 U3

Table 2: Pipe dimensions and wall thicknesses for three-layer pipes with one. peak stiffness of 8 kN / m2 (SN 8) DN dl (mm) si min (mm) cm min (mm) sa min (mm) s total min (mm) s real (mm) 110 110.00 0.60 3.00 0.50 4.10 4.60 125 125.00 0.60 3.50 0.50 4.60 5.20 160 160.00 0.60 4.70 0.50 5.80 6.70 200 200.00 0.60 6.00 0.50 7.10 8.30 250 250.00 0.70 7.50 0.60 8.80 10.30 315 315.00 0.80 9.50 0, 70 11.00 13.00 400 400.00 1.00 12.10 0.80 13.90 16.50 500 500.00 1.10 15.30 0.90 17.30 20.70 600 600.00 1 , 20 19.40 1, 00 21.60 26.00 dl Outer diameter 15 Sa Thickness, outer layer Sm Thickness, middle layer Si Thickness, inner layer Total Thickness, total Sreal Recommended thickness, example 20 min relevant minimum value.

The inner layer 2 and / or the outer layer 1 can also consist of other plastic types than the middle layer 3, which for example consists of PP, when these are joined by means of adhesives - ie two additional layers - to the middle layer 3. These plastic types for the outer and / or inner layers 1 and 2 may be, for example: 8 DK 97 00296 U3

Polyethylene (PE)

Acrylonitrile-styrene-butadiene copolymer (ABS) Copolymers of styrene or acrylonitrile (SAN)

Polyamide (PA)

The generation enables very little use of polymer (improvement of the ecological balance) when the requirements for pressure-free drainage pipes have to be met, and that with improved economy compared to pipes with solid walls and pipes where only the middle layer is filled. In addition, improved properties can be obtained in relation to pipes where the middle layer is only foamed (not reinforced or filled):

Thinner wall at the same stiffness, higher long-term stiffness, larger E-module, improved creep factor, greater production speed, and improved cooling during manufacture.

Compared to mineral-reinforced (non-foamed) pipes that are mineral-reinforced only, there are the following advantages:

Improved thermal insulation, improved internal temperature effect, cost savings and low weight.

In the embodiment of FIG. 2, the preferred area of the structure of the foamed layer, which is preferably the middle layer of a three-layer tube, is shown by cross-shading. In this preferred range, the PP proportion is preferably between 25 and 70%, and the mineral material proportion is also preferably between 25 and 70%. Compared to a layer that is only reinforced with mineral material and not foamed, the density is at least 10% less. By way of example, a composition of the middle layer is provided containing 30% talc, 55% polypropylene and 15% foamed PP.

Claims (17)

A multilayer plastic tube which is new in that at least one layer (3), preferably the middle layer (3), consists of a polyolefin reinforced with a mineral material or a mixture of mineral materials, the proportion of polyolefin in this layer. (3) is 25-70% by weight, and that this layer is foamed so that it has a density at least 10% less than the density of a non-foamed mineral reinforced layer of identical composition. A pipe according to claim 1, which is new in that a sleeve is formed in one with the pipe. Pipe according to claim 1 or 2, which is new in that the foamed layer (3) contains recycled material from pipes of the same plastic. DK 97 00296 U3 Pipe according to one of claims 1-3, which is new in that the plastic in the foamed layer (3) contains up to 50% by weight polyolefin "recyclate". Pipe according to one of claims 1-4, which is new in that the thickness of the layer 5 (3) is at least 50% of the total pipe wall thickness. Pipe according to one of claims 1 to 5, which is new in that the foamed layer (3) and / or a layer (2) disposed within said layer consists of polypropylene with a partial mesh structure. 10 Pipe according to one of claims 1 to 5, which is new in that the foamed layer (3) and / or a layer (2) disposed within it consists of a mixture of polypropylene and polypropylene with a partial mesh structure. The tube of claim 7, which is new in that the mixture consists of 10 to 50% by weight, preferably 15 to 25% by weight, of polypropylene partially with a partial mesh structure, related to 100 parts of PP base (e.g. polypropylene copolymer). ). Pipe according to one of claims 1-8, which is new in that the foamed layer (3) is filled with talc and / or chalk as a mineral material. A tube according to any one of claims 1-9, as a new one, wherein the middle layer is foamed so that it has a density up to 0.9 g / cm 3, preferably 0.8 g / cm 3. Pipe according to one of claims 1 to 5 and up to 10, which is new in that the foamed layer (3) consists of mineral reinforced polypropylene. Tube according to one of claims 1 to 11, as a new one in that the outer layer (1) and the inner layer (2) consist of polypropylene. DK 97 00296 U3 Pipe according to one of claims 1-12, as a new one in that the inner layer (2) and the outer layer (1) consist of the same polyolefin as the foamed mineral reinforced middle layer (3). Pipe according to one of claims 1-13, which is new in that the inner layer (2) has a higher, finely distributed, average degree of crystallisation than the outer layer (1). The tube according to claim 14, as a new one, in that the polymer of the middle layer (3) has a higher, finely distributed, average degree of crystallization than the outer layer (1). 10 Pipe according to one of claims 1-15, which is new in that the pipe is made by coextrusion with external cooling and internal tempering. The tube according to claim 16, which is new in that the spherolite formation or the higher crystallinity of the inner layer (2) is controlled 15 during manufacture.