CH691048A5 - Plastic sealing sheet for rubbish dumps, roads, buildings etc. - Google Patents

Abstract

Plastic sealing sheet (I) with appreciably better biaxial extensibility than conventional sheet, comprising upper layer (A), lower layer (C) and a barrier layer (B) between (A) and (C). All three layers are based on organic polymers, those in layers (A) and (C) having better mechanical properties than the polymer(s) in layer (B). Layers (A) and (C) may be based on the same or different polymer(s), and the polymer in (B) is such that biaxial extension of the strip causes no damage to this layer. Biaxial extension also causes no interlaminar sepn.. Also claimed is a process for the prodn. of (I).

Description

       

  



  The present invention relates to a plastic sealing membrane, comprising a composite of an upper layer and a lower layer and an intervening barrier layer.



  The present invention also relates to methods for producing this plastic sealing membrane and to the use thereof.



  Plastic sealing sheets based on ethylene homopolymers and / or ethylene copolymers and propylene homopolymers and / or propylene copolymers are known. See, for example, the products of the National Seal Company in Aurora, IL 60504, USA, and products from the Montell Polyolefins company in 1-44100 Ferrara, Italy.



  Plastic sealing sheets made of PE-HD (polyethylene high density) with a barrier layer made of exclusively rolled aluminum foils (about 50 to about 250 micrometers thick) are known.



  Even at low biaxial strains, this aluminum barrier layer tears, and the barrier function is significantly reduced.



  In the case of the plastic sealing sheet described in DE OS 3 514 383, the inner layers - quote - must have at least approximately the same mechanical properties as those of the outer plastic sheets - quote end.



  The - quotation - high extensibility - end of quotation - mentioned in DE OS 3 514 383 relates to a monoaxial extensibility which has nothing to do with biaxial stretching.



  PE-HD geomembranes are mainly used to line landfills.



  Plastic sheets of this type have a low biaxial elongation and, because of their low flexibility, adapt poorly to the sealing carrier.



  If the maximum value of the biaxial elongation is exceeded, the plastic web breaks. The result of this is that pollutants can get into the water, the ground or the atmosphere through the cracks that have formed.



  Conventional geomembranes based on polyethylene should not be used to seal landfills due to the high permeation rates, such as with halogenated hydrocarbons such as dichlorobenzene.



  It is an object of the present invention to overcome the above drawbacks.



  It is a further object of the present invention to provide a plastic sealing sheet which has an organic material barrier layer which inhibits the diffusion of pollutants, such as aromatic and halogenated hydrocarbons, for example dichlorobenzene, dichloromethane.



  This plastic sealing membrane is said to have a high degree of flexibility combined with a high biaxial stretch and a high relaxation capacity.



  In particular, a new product with a thickness (thickness) of 1.5 mm to 5 mm, which contains no plasticizers or bitumen, and a good weather resistance is to be made available, which is flexible in the operating temperature range from -40 ° C. to + 70 ° C. as well as good and easy processability, in particular weldability with conventional welding techniques and welding equipment (double heating wedge seam, extrusion seam, hot gas manual welding, mechanical hot gas welding), and good chemical, biological and bitumen resistance.



  It should also not contain any heavy metal stabilizers.



  The new product should be assembled, manufactured and processable for the respective application in such a way that it results in a very good price / performance ratio compared to the state of the art.



  For use in underwater seals, for example underwater landfills, the density of this plastic sealing membrane should be adjustable for the purpose of easier laying.



  In this application, the density should preferably be 1.2 g / cm 3 to 1.4 g / cm 3.



  Furthermore, simple and cheap processes for the production of this new product are to be made available.



  This invention is characterized by the features in the independent claims.



  Preferred embodiments are defined in the dependent claims.



  The plastic sealing sheets according to the invention have excellent basic properties which result from the composition of the individual components and the production process, as are described in the examples below.



  In addition, the following features characteristic of the invention are found:
 - Permeability to pollutants, such as 1,2-dichlorobenzene, equal to or less than 0.002 g / 10 <4> m <2> / year at a pollutant concentration of 30 mg / liter H2O;
 - excellent flexibility;
 - excellent thermal aging resistance;
 - good weather resistance (when using 2.5% soot);
 - Good chemical and biological aging resistance, especially in contact with aqueous media, bituminous substances, microorganisms;
 - good flexibility at low temperatures, low stiffening at low temperatures;
 - good bond, good welding of the layers within the plastic sealing membrane;
 - ecological safety;

   in particular no bitumen, no plasticizers, no heavy metal stabilizers, such as Pb, Cd, no smoke and / or odor during production and processing, recyclable, safe disposal by landfill or incineration;
 - Good processability, especially good weldability for the described applications with conventional welding techniques and welding equipment (hot air, heating wedge, etc.).



  The quality of the welded connections between the individual sheets to form flat seals corresponds to the DVS standard 2203, parts 1-5 ("German Association for Welding Technology e.V.").



  Because the plastic sealing sheets according to the invention are flexible, they adapt better to the respective subsurface.



  This results in a flat, tight press bond between the plastic sealing membrane according to the invention and the substrate.



  The advantage of a flat, full press fit is that only little, if any, tension is present in the plastic sealing membrane according to the invention.



  It is possible to build up the barrier layer in multiple layers. The appropriate barrier layers are bonded together using a suitable bonding agent.



  In the following part, further possible methods for producing the plastic sealing sheets according to the invention are mentioned:
 - co-extrusion process (blow molding or slot die)
 - Combinations of different process technologies.



  The upper layer and the lower layer are applied to the barrier layer, with or without adhesion promoter, on a melt roller calender either simultaneously on-line or successively off-line.



  The barrier layer, with or without adhesion promoter, is laminated on a laminating system with the top layer and with the bottom layer.



  The upper and lower layers are produced either on a film calender or on a mono-extrusion line.



  The following examples illustrate the present invention.


 example 1
 



  In order to produce a plastic sealing membrane with a total thickness of 2.5 mm, in which the top layer and the bottom layer are of the same nature, the following components were fed into a twin screw extruder running in the same direction:
<tb> <TABLE> Columns = 2
<tb> Head Col 1: components
<tb> Head Col 2:% by weight
<tb> <SEP> VLDPE (Very low density polyethylene) with a density of 0.910 g / cm <3> <SEP> 62.6
<tb> <SEP> VLDPE with a density of 0.914 g / cm <3> <SEP> 31.3
<tb> <SEP> compound consisting of
<tb> <SEP> 40% by weight VLDPE (d = 0.910 g / cm <3>)
<tb> <SEP> 20% by weight VLDPE (d = 0.914 g / cm <3>)
<tb> <SEP> 40% by weight carbon black (as pigment and light stabilizer)
<tb> <SEP> with a density of 1.140 g / cm <3> <SEP> 6.0
<tb> <CEL AL = L> heat stabilizer <CEL AL = L> 0.1.
<tb> </TABLE>



  In this twin-screw extruder, these components were plasticized, mixed homogeneously and extruded through a slot die (working width 1 m). The material was dosed into the extruder using a differential dosing scale.



  The temperature of the sheet-like mass emerging from the slot die was 220 ° C. to 230 ° C. The output was 130 kg per hour.



  This web-like mass was introduced from above into the lower nip of a 3-roll calender. At the same time, the barrier layer ran in from below via the lower roller at a speed of 1.6 m / minute.



  The barrier layer was a prefabricated, 70 micron thick film made of PVDC (polyvinylidene chloride), which was coated on both sides with EVA (ethylene-vinyl acetate copolymer) as an adhesion promoter (25 microns each).



  In order to obtain optimal adhesion between the first layer to be formed (top layer) and the adhesion promoter layer, a material template was used in order to obtain the necessary contact pressure.



  The temperature of the lower roll was 60 ° C. to 90 ° C., that of the middle roll from 40 ° C. to 60 ° C. The thickness of the web was set at 1.2 mm via the gap between the lower and middle roll. The web was then cooled to room temperature via cooling rolls and wound up.



  In a second step, the second layer (sub-layer) was completely welded to the sheet produced in the first step. Placement, homogenization and extrusion were carried out in the same manner as described above.



  The web-like mass emerging from the slot die was introduced into the lower nip of a 3-roll smoothing unit.



  At the same time, the web from the first operation ran in from below via the lower roller, the barrier layer being directed to the side with the material template.



  The temperature of the lower roller was 30 ° C. to 50 ° C., that of the middle roller 50 ° C. to 80 ° C. The thickness of the web was set at 2.5 mm via the gap of the lower and middle roller.



  This web was then cooled to room temperature via chill rolls, the edges were cut and the web was rolled up.



  The web thus obtained had the following properties:
<tb> <TABLE> Columns = 5
<tb> Head Col 1 to 2 AL = L: test
<tb> Head Col 3 AL = L: norm
<tb> Head Col 1: unit
<tb> Head Col 2: value
<tb> <SEP> web thickness <SEP> DIN 53370 <SEP> mm <SEP> 2.5
<tb> <CEL CB = 1 CE = 2 AL = L> density of the web <SEP> - <SEP> g / cm <3> <SEP> 0,

  93
<tb> <SEP> tear strength <SEP> longitudinal <SEP> DIN 53455 <CEL AL = L> N / mm <2> <SEP> 24
<tb> <SEP> across <SEP> 24
<tb> <SEP> elongation at break <SEP> longitudinal <SEP> DIN 53455 <SEP>% <SEP> 750
<tb> <SEP> across <SEP> 750
<tb> <SEP> yield stress <SEP> along <SEP> DIN 53455 <SEP> N / mm <2> <SEP> 7
<tb> <SEP> across <SEP> <CEL AL = L> <SEP> 7
<tb> <SEP> elongation at yield stress <SEP> along <SEP> DIN 53455 <SEP>% <SEP> 16
<tb> <CEL CB = 2 AL = L> across <SEP> 16
<tb> <SEP> folding in the cold <SEP> SIA 280/2 <SEP> DEG C <SEP> <-50
<tb> <SEP> shape change in the heat <SEP> along <SEP> SIA 280/3 <SEP>% <SEP> <1
<tb> <CEL CB = 2 AL = L> across <CEL CB = 5 AL = L> <1
<tb> <SEP> thermal aging (70 days, 70 ° C) <SEP> SIA 280/7
<tb> <SEP> - mass change <SEP>% <SEP> -0.05
<tb> <SEP> biaxial elongation <SEP> - <SEP>% <SEP> 180
<tb> <SEP> (pressure pot diameter: 180 mm
<tb> <SEP> test temperature:

   23 DEG C)
<tb> <CEL CB = 1 CE = 2 AL = L> Permeability to 1,2-dichlorobenzene (DCB) <SEP> - <SEP> g / 10 <4> m <2> / year <SEP> 0.002
<tb> <SEP> (c = 30 mg / liter H2O)
<tb> <SEP> Tear resistance <SEP> DIN 53363 <SEP> N / mm <SEP> 206
<tb> <SEP> flexibility (torsion measurement)
<tb> <SEP> memory module G min [mPa]
<tb> <CEL CB = 1 CE = 2 AL = L> T = -20 DEG C <SEP> 285
<tb> <SEP> T = 0 DEG C <SEP> 150
<tb> <SEP> T = 23 DEG C <CEL CB = 5 AL = L> 76
<tb> </TABLE>


 Example 2
 



  The following components were processed analogously to Example 1:
<tb> <TABLE> Columns = 2
<tb> Head Col 1: components
<tb> Head Col 2:% by weight
<tb> <SEP> VLDPE with a density of 0.910 g / cm <3> <SEP> 31.3
<tb> <SEP> VLDPE with a density of 0.914 g / cm <3> <SEP> 15.6
<tb> <SEP> compound consisting of
<tb> <SEP> 40% by weight VLDPE (d = 0.910 g / cm <3>)
<tb> <SEP> 20% by weight VLDPE (d = 0.914 g / cm <3>)
<tb> <SEP> 40% by weight carbon black (as pigment and light stabilizer)
<tb> <SEP> with a density of 1.140 g / cm <3> <SEP> 3.0
<tb> <SEP> heat stabilizer <SEP> 0.1
<tb> <SEP> compound consisting of
<tb> <SEP> 20% by weight VLDPE (d = 0.910 g / cm <3>)
<tb> <SEP> 10% by weight VLDPE (d = 0.914 g / cm <3>)
<tb> <SEP> 70% by weight BaSO4
<tb> <SEP> with a density of 1.955 g / cm <3> <SEP> 50
<tb> </TABLE>



  The web thus obtained had the following properties:
<tb> <TABLE> Columns = 5
<tb> Head Col 1 to 2 AL = L: test
<tb> Head Col 3 AL = L: norm
<tb> Head Col 1: unit
<tb> Head Col 2: value
<tb> <SEP> web thickness <SEP> DIN 53370 <SEP> mm <SEP> 2.5
<tb> <CEL CB = 1 CE = 2 AL = L> density of the web <SEP> - <SEP> g / cm <3> <SEP> 1.246
<tb> <SEP> tear strength <SEP> longitudinal <SEP> DIN 53455 <CEL AL = L> N / mm <2> <SEP> 18.7
<tb> <SEP> across <SEP> 18.7
<tb> <SEP> elongation at break <SEP> lengthways <SEP> DIN 53455 <SEP>% <SEP> 500
<tb> <SEP> across <SEP> 500
<tb> <SEP> fold bending in the cold <CEL CB = 3 AL = L> SIA 280/2 <SEP> DEG C <SEP> <-50
<tb> <SEP> shape change in the heat <SEP> along <SEP> SIA 280/3 <CEL AL = L>% <SEP> <1
<tb> <SEP> heat <SEP> across <SEP> <1
<tb> <SEP> thermal aging (70 days, 70 ° C) <SEP> SIA 280/7
<tb> <SEP> - mass change <SEP>% <SEP> -0.05
<tb> <CEL CB = 1 CE = 2 AL = L> biaxial elongation <SEP> - <SEP>% <SEP> 111
<tb> <SEP> (pressure pot diameter:

   180 mm
<tb> <CEL CB = 1 CE = 2 AL = L> test temperature: 23 ° C)
<tb> <SEP> flexibility (torsion measurement)
<tb> <SEP> memory module G min [mPa]
<tb> <SEP> T = -20 DEG C <SEP> 354
<tb> <SEP> T = 0 DEG C <SEP> 182
<tb> <SEP> T = 23 DEG C <SEP> 90
<tb> </TABLE>


 Example 3
 



  The following components were processed analogously to Example 1:
<tb> <TABLE> Columns = 2
<tb> Head Col 1: components
<tb> Head Col 2:% by weight
<tb> <SEP> VLDPE with a density of 0.910 g / cm <3> <SEP> 31.3
<tb> <SEP> VLDPE with a density of 0.914 g / cm <3> <SEP> 15.6
<tb> <SEP> compound consisting of
<tb> <SEP> 40% by weight VLDPE (d = 0.910 g / cm <3>)
<tb> <SEP> 20% by weight VLDPE (d = 0.914 g / cm <3>)
<tb> <SEP> 40% by weight carbon black (as pigment and light stabilizer)
<tb> <SEP> with a density of 1.140 g / cm <3> <SEP> 3.0
<tb> <SEP> heat stabilizer <SEP> 0.1
<tb> <SEP> compound consisting of
<tb> <SEP> 20% by weight VLDPE (d = 0.910 g / cm <3>)
<tb> <SEP> 10% by weight VLDPE (d = 0.914 g / cm <3>)
<tb> <SEP> 70 wt% TiO2
<tb> <SEP> with a density of 2.030 g / cm <3> <SEP> 50
<tb> </TABLE>



  The web thus obtained had the following properties:
<tb> <TABLE> Columns = 5
<tb> Head Col 1 to 2 AL = L: test
<tb> Head Col 3 AL = L: norm
<tb> Head Col 1: unit
<tb> Head Col 2: value
<tb> <SEP> web thickness <SEP> DIN 53370 <SEP> mm <SEP> 2.5
<tb> <CEL CB = 1 CE = 2 AL = L> density of the web <SEP> - <SEP> g / cm <3> <SEP> 1.261
<tb> <SEP> tear strength <SEP> longitudinal <SEP> DIN 53455 <CEL AL = L> N / mm <2> <SEP> 15
<tb> <SEP> across <SEP> 15
<tb> <SEP> Elongation at break <SEP> along <SEP> DIN 53455 <CEL AL = L>% <SEP> 450
<tb> <SEP> across <SEP> 500
<tb> <SEP> folding in the cold <SEP> SIA 280/2 <SEP> DEG C <SEP> <-50
<tb> <SEP> change in shape in the heat <SEP> along <SEP> SIA 280/3 <SEP>% <CEL AL = L> <1
<tb> <SEP> across <SEP> <1
<tb> <SEP> thermal aging (70 days, 70 ° C) <CEL CB = 3 AL = L> SIA 280/7
<tb> <SEP> - mass change <SEP>% <SEP> -0.05
<tb> <SEP> biaxial elongation <SEP> - <SEP>% <SEP> 102
<tb> <SEP> (pressure pot diameter:

   180 mm
<tb> <CEL CB = 1 CE = 2 AL = L> test temperature: 23 ° C)
<tb> <SEP> flexibility (torsion measurement)
<tb> <SEP> memory module G min [mPa]
<tb> <SEP> T = -20 DEG C <CEL CB = 5 AL = L> 425
<tb> <SEP> T = 0 DEG C <SEP> 213
<tb> <SEP> T = 23 DEG C <SEP> 106
<tb> </TABLE>


    

Claims (20)

  1. Plastic sealing membrane, comprising a composite of an upper layer and a lower layer and an intermediate barrier layer, characterized in that  the barrier layer is constructed on the basis of at least one organic polymeric material,  the top layer and the bottom layer are based on at least one such organic polymeric material which has better mechanical properties compared to the organic polymeric material used in the said barrier layer,  - said top layer and bottom layer are made of the same or different materials,  the organic polymeric material mentioned for the barrier layer is such that it is not damaged when the plastic sealing membrane is stretched biaxially,  and  - With a biaxial expansion of the plastic sealing membrane, there is no separation of the layers. 2. Plastic sealing membrane according to claim 1, characterized in that the bond between the top layer and the barrier layer, or between the bottom layer and the barrier layer takes place by means of at least one bonding agent, and wherein the bonding agent for the bond between the top layer and the barrier layer is independent of the bonding agent for the bond between the bottom layer and the barrier layer is selected. 3. Plastic sealing membrane according to one of claims 1 to 2, characterized in that the adhesion promoter is selected from the group consisting of  - adhesive polyolefins,  - adhesive acetate resins,  - copolymers of vinyl acetate,  - adhesive polyurethanes,  - adhesive acrylic resins, and  - Copolymers of acrylic esters. 4th  Plastic sealing membrane according to one of claims 1 to 3, characterized in that the adhesion promoter is an adhesive polyolefin modified with maleic anhydride. 5. Plastic sealing membrane according to one of claims 1 to 4, characterized in that the organic polymeric material for the barrier layer is selected from the group consisting of  - polyamides,  Polyvinyl halides and polyvinylidene halides, in particular polyvinyl fluoride and polyvinylidene chloride,  Polyethylene terephthalates, optionally vapor-coated with metallic aluminum,  Ethylene vinyl alcohols, including their copolymers,  with polyvinylidene chloride and polyvinyl fluoride being preferred. 6.  Plastic sealing membrane according to one of claims 1 to 5, characterized in that the organic polymeric material for the top layer and the bottom layer is selected from the group consisting of  - polyurethanes,  Ethylene homopolymers and / or ethylene copolymers, in particular with a density equal to or less than 0.920 g / cm 3,  Propylene homopolymers and / or propylene copolymers, in particular with a density equal to or less than 0.920 g / cm 3,  an ethylene copolymer having a density of 0.900 g / cm 3 to 0.915 g / cm 3 is preferred, and the comonomers are preferably alpha-olefins having 4 to 12, in particular 6 to 10, carbon atoms. 7.  Plastic sealing membrane according to one of claims 1 to 6, characterized in that the upper layer and / or the lower layer, depending on the application, at least one pigment, in particular titanium dioxide, light-resistant color pigments, and / or we least one stabilizer, in particular light stabilizers, antioxidants , Heat stabilizers, and / or at least one filler, in particular chalk, kaolin, talc, quartz powder, barium sulfate, and / or at least one processing aid, in particular lubricants, for example Glycerol monostearate, contain (contains). 8th.  Plastic sealing membrane according to one of claims 1 to 7, characterized in that the upper layer and / or lower layer  - up to 15 wt .-% pigment, and / or  - up to 5 wt .-% stabilizer, and / or  - up to 40 wt .-% filler, and / or  - up to 5% by weight of processing aids,  contain (contains), the sum of all components present being 100% by weight. 9. Plastic sealing membrane according to one of claims 1 to 8, characterized in that with a biaxial elongation of 40%, neither the barrier layer is damaged nor a separation of the layers occurs. 10. Plastic sealing membrane according to one of claims 1 to 9, characterized in that it has the following layer thicknesses:  - top layer and bottom layer: each 0.75 mm to 2.5 mm,  - Barrier layer: 50 microns to 200 microns. 11.  Plastic sealing membrane according to one of claims 1 to 10, characterized in that the width of the top layer and the width of the bottom layer on each side of the plastic sealing membrane is greater than the width of the barrier layer, and that the said difference in size is preferably at least 5 mm, and that The upper layer is thermally welded to the lower layer in the edge region mentioned. 12. Plastic sealing membrane according to one of claims 1 to 11, characterized in that the top layer, the bottom layer and the barrier layer are each homogeneous and single-layer. 13.  A process for the production of the plastic sealing sheets according to one of claims 1 to 12, characterized in that in a first step the required formulation components for the first layer are plastified and homogeneously mixed in a first extruder and extruded via a slot die, then the thus obtained first web-like mass in a first nip between two rollers, forming a melt bead, thermally welded from one side to the incoming barrier layer under the action of pressure, and then in a second step the on-line recipe components required in each case in the same operation plasticized and homogeneously mixed for the second layer in a second extruder and extruded through a slot die, then with the second web-like mass obtained in this way in a second nip between two rollers,  forming a melt bead, thermally welded from the other side under the action of pressure with the incoming web obtained from the first step. 14. The method according to claim 13, characterized in that the plastic sealing sheet thus obtained is cooled, and / or embossed, and / or laminated, and / or cut, and / or wound. 15. The method according to any one of claims 13 to 14, characterized in that the barrier layer is provided on one side or on both sides with at least one adhesion promoter. 16.  Process for the production of the plastic sealing sheets according to one of claims 1 to 12, characterized in that in a first step the required formulation components for the first layer are plastified and homogeneously mixed in an extruder and extruded via a slot die, then the first so obtained sheet-like mass in a gap between two rollers, forming a melt bead, thermally welded from one side to the incoming barrier layer under the action of pressure and cooling and winding up the product thus obtained, and then in a second operation, off-line, as required Recipe components for the second layer plastified and homogeneously mixed in an extruder and extruded through a slot die, then with the second web-like mass obtained in this way in a gap between two rollers,  forming a melt bead, under the action of pressure, the incoming web obtained from the first operation, thermally welded from the other side. 17. The method according to claim 16, characterized in that the plastic sealing sheet thus obtained is cooled, and / or embossed, and / or laminated, and / or cut, and / or wound. 18. The method according to any one of claims 16 to 17, characterized in that the barrier layer is provided on one side or on both sides with at least one adhesion promoter. 19. Use of the plastic sealing membrane according to one of claims 1 to 12  - For sealing, covering, lining, insulation of landfills, which are intended to hold liquid and solid waste. 20th  Use of the plastic sealing sheets according to one of claims 1 to 12  - for the protection of water and groundwater as well as soils, in particular under and / or on modes of transport, for example motorways, airports, rail systems, and industrial plants, for example tank systems, transhipment points, production facilities and warehouses,  - For the protection of structures that are in contact with contaminated media, especially contaminated soil or contaminated water.