CA1090934A

CA1090934A - Thermoplastic materials

Info

Publication number: CA1090934A
Application number: CA293,250A
Authority: CA
Inventors: Harald Blumel
Original assignee: Chemische Werke Huels AG
Current assignee: Huels AG
Priority date: 1976-12-17
Filing date: 1977-12-16
Publication date: 1980-12-02
Also published as: NL7713991A; JPS5375251A; DE2657274A1; FR2374359A1; GB1595603A; BE861954A

Abstract

Abstract of the Disclosure Improved thermoplastic materials are disclosed for use in the production of mouldings having low water permeability and absorption. The materials comprise: (a) 100 parts by weight of a polyolefin rubber; (b) from 15 to 50 parts by weight of a crystalline or partly crystalline polyolefin;
(c) from 30 to 140 parts by weight of a carbon black; (d) from 5 to 150 parts by weight of a bitumen or mineral oil; and (e) from 3 to 360 parts by weight of chalk or siliceous chalk.

Description

109093~

This invention relates to thermoplastic materials and their use for the production of mouldings, particularly web and sheeting, having low water vapour permeability and at the same time low water absorption.
It is known that thermoplastic materials may be used for example in the form of web or sheeting for sealing against moisture. They may be united either by heat sealing or by a swelling agent or special adhesive to form larger sealing surfaces and either laid loosely on the substructure of, for example, concrete, wood, bitumen or air-containing thermal insulating material or stuck all over or at isolated places by special sheet a& esives to the said substructure.
To provide a seal against flowing or static water a thickness of the material of from 1 to 2 mm and the presence of a closed surface are sufficient.
Particularly in building construction, for example in sealing flat roofs, there are used for keeping the necessary layers of thermal insulation dry so-called vapour-lock sheeting which has to have a specific minimal resistance to the diffusion of water vapour. It is important that the sheeting which insulates the thermal insulating layer from the moisture of the building has a lower water vapour diffusion than the sealing membrane situated above the thermal insulation for protection against rain. This precludes accumulation of mois-ture in or on the thermal insulation layer and consequent loss or diminution of its function.
It is however often required of sheeting or web used for insulating purposes that it should have - in addition to low water vapour permeability -a low water absorption because the durability behaviour and the life in rela-tion to the corrosive aqueous liquids encountered in some environments of use, for example in structural work below ground, is considerably better in the case of low water absorption.
It is therefore an object of the invention to develop a thermoplastic material which, particularly in the form of web or sheeting, has a good water vapour permeability and at the same time a low water absorption. Moreover it ~Y~

should naturally have the properties which are essential in any case for the use of such material for the production of insulating web or sheeting, namely favourable rheological behaviour, good heat-sealing properties, adequate mechanical properties and also resistance to the effects of weathering and aggressive media and thermo-mechanical influences at high and low temperatures.
According to the invention, there is provided a thermoplastic ma-terial which consists of:
(a) 100 parts by weight of a polyolefin rubber;
~b) from 15 to 50 parts by weight of a crystalline or partly crystalline polyolefin;
(c) from 30 to 140 parts by weight of a carbon black;
(d) from~ to 150 parts by weight of a bitumen or mineral oil; and ~e) froml~ to 360 parts by weight of chalk or siliceous chalk.
Within the scope of the present invention the polyolefin rubber which forms the basis of the thermoplastic material according to the invention may be a polymer prepared from ethylene, one or more ~-olefins of three to eight carbon atoms, particularly propylene, with or without one or more multi-olefins by means of a Ziegler-Natta catalyst which may additionally contain an activator and a modifier, in solution or dispersion, at a temperature of from -30C to +100C, for example by the method of DT-OS 1,570,352, 1,595,442 or 1,720,450 and also DT-OS 2,427,343.
Polyolefin rubbers are preferred which are saturated and consist of 15 to 90% by weight and more preferably 30 to 75% by weight of ethylene and 85 to 10% and more preferably 70 to 25% by weight of propylene and/or butene-(1) or are unsaturated and consist in addition to ethylene and propylene or butene-(l) of a multi-olefin, namely in such an amount that 0.5 to 30 double bonds are contained per 1000 carbon atoms in the rubber. Particularly pre-ferred multi-olefins include cis-hexadiene-~1,4), dicyclopentadiene, 5-methylene-2-norbornene, 5-ethylidene-2-norbornene and 5-isopropylidene-2-norbornene.

109093~

Polyolefins which are added to the material according to the inven-tion in an amount of from 15 to 50 parts by weight and preferably from 20 to 40 parts by weight include first of all a crystalline or partly crystalline modification of polyethylene having a density of from 0.910 to 0.975 g/cm3, an RSV value (measured at 135C in decalin (decahydronaphthalene)) of from 0.5 to 3.3 dl/g and a melt index of from 0.2 to 50 g/lnmin. It is possible however to use partly crystalline copolymers of ethylene with another -olefin within the limits of the said specification. Also suitable are crystalline and partly crystalline homopolymers and copolymers (with other ~-olefins and preferably with ethylene) of propylene or butene-(l), namely homopolymers and copolymers of propylene having densities of from 0.90 to 0.910 g/cm3 RSV va-lues (measured at 135C in decalin) of 1.0 to 10 dl/g and melt indices of 0.1 to 50 g/ln min, and homopolymers and copolymers of butene-(l) having densities of from 0.910 to 0.925 g/cm3, RSV values (measured at 135C in decalin) of 1.0 to 10 dl/g and melt indices of 0.1 to 100 g/10 min.
To improve the heat-sealing properties of mouldings prepared from the material according to the invention it is also possible to use - in addi-tion to the crystalline and/or partly crystalline polyolefins - a small amount (up to about one-third of the weight of the crystalline and/or partly crystal-line polyolefin) of atactic polypropylene and/or polybutene-l having a density of 0.86 g/cm3 and RSV values (measured at 135C in decalin) of 0.1 to 3.0 dl/g Suitable carbon blacks include those prepared by the furnace method, especially of the types FEF (fast extruding furnace black), GPF (general pur-pose furnace black), HMF (high modulus furnace black) APF (all purpose furnace black), HAF (high abrasion furnace black), FT (fine thermal black), MT (medium thermal black) and SRF (semi-reinforcing furnace black). The carbon blacks are added to the material according to the invention in an amount of from 30 to 140 parts by weight and preferably from 40 to 120 parts by weight. The materials also include as further filler from 3 to 360 parts by weight, gene-30 rally from 3 to 350 parts by weight and preferably from 30 to 300 parts by weight, of chalk and/or siliceous chalk. These include natural, ground pig-ments containing mainly calcium carbonate and/or silicic acid or precipitated calcium carbonate which may have been coated for example with a fatty acid derivative, in the form customarily used in processing rubber.
Finally the material according to the invention includes from 5 to 150 parts by weight, generally from 5 to 120 parts by weight and preferably from 25 to 100 parts by weight of a bitumen or mineral oil.
Suitable bitumens include liquid to solid distillation residues from petroleum refining consisting mainly of highly condensed hydrocarbons; their structure may be partially changed for example by oxidation (blown bitumens).
Suitable mineral oils are those having viscosities of from 50 to 5000 centistokes at 20C and preferably of from 200 to 3000 centistokes at 20C and a density of 0.84 to 0.98 g/cm3. The oils may contain paraffinic carbon atoms and also naphthenic or aromatic carbon atoms.
Production of the claimed thermoplastic material may be carried out for example in a commercial internal mixer with floating weight, with or with-out heating. The period required for homogenisation depends on the formula-tion, the structure of the starting material, the constructional features of the mixi~g plant and of the further processing units and the process conditions 20 chosen such as temperatures of the material (generally from 50 to 220C and preferably from 80 to 150C), the extent to which the internal mixer is filled (generally from 1.0 to 1.8 and preferably from 1.2 to 1.5 based on its effec-tive volume) and the speed of the rotor (generally up to 100 and preferably from 10 to 40 rpm) and is generally from 1 to 100 minutes and preferably 35 minutes. After adequate homogenisation the material, usually having a tempera-ture of from 50 to 220C, is discharged. In the case of mixtures containing a high concentration of bitumen it may be necessary in order to preclude con-siderable adhesion to casing and rotors (which may prevent substantially the discharge of the material) to cool the same prior to the discharge (cooling 30 period from 1 to 30 minutes and preferably from 3 to 15 minutes).

The material discharged from the internal mixer is then converted into strips or strings for example through a pair of rollers or a unit driven by a screw and either granulated or transferred immediately to a further pro-cessing unit.
This further processing unit which serves particularly for the pro-duction of the web or sheeting may be for example a calender, an extruder with a flat sheeting die or so-called roller-head plant. It may be provided with means for applying or introducing carrier materials, as for example fleece of synthetic fibres and glass cloth.
The material according to the invention which is distinguished by good water vapour permeability and at the same time low water absorption and which is also distinguished by good strength at elevated temperatures may be used, especially in the form of web or sheeting, both in superstructures for example for sealing buildings having flat roofs and in substructures for ex-ample for linings for collecting basins, keeping tanks, settling tanks~ stor-age basins and for laying out pools, canals and artificial lakes. Other applications are as a sealing sheeting for breaches, tunnels, subways and underpasses and for bridge building and skyscraper sealing in areas of subsoil water.
The following Examples serve to illustrate the present invention.
Example 1 In a laboratory kneader having an effective volume of 2 litres of the Werner ~ Pfleiderer GK2 type with a ram there are mixed the ethylene-propylene-diene rubber identified as EPDM I (diene = ethylidene nor~ornene;
30% by weight of propylene; 8 double bonds per 1000 carbon atoms; MLl+4 (at 100C~ = 87; polymer crude strength = 130 kp/cm2) with the following products according to the stated mixing periods at a temperature of 90C at the outlet from the kneader and a rotor speed of 50 rpm.

Mixing procedure: Time (minutes) introduction of 703 g of EPDMI 0 introduction of 703 g of bitumen B 85/25 introduction of 633 g of FEF carbon black introduction of 1407 g of chalk introduction of 211 g of polyethylene ~density 0.945 g/cm3, RSV 1.45 dl/g, 3 melt index 7 g/10 min) ram cleaned 4 discharge 9 The homogeneous material is discharged with a material temperature of 150C and then converted on a laboratory roll mill having a surface tem-perature of 50C into a rough sheet which is cut into strips or granulated.
The strips or granules are converted into web of a thickness of 1 mm in a Kleinewefer laboratory extruder with a flat die 300 mm in width arranged in front and a two-roll smoothing calender arranged behind. Portions taken from this web are investigated according to DIN 52122 for water vapour permeability and according to DIN 53495, method A, for water absorption. The water absorption after a storage period of 24 hours is 0.15% and after 200 hours is 0.25% by weight. The water vapour permeability resistance factor, calculated according to DIN 52615 is ~ = 145,000.
Example 2 Example 1 is repeated with the difference that 1407 g of siliceous chalk is used instead of chalk and the material is discharged at a material temperature of 160C. Strips also prepared as described in Example 1 are shaped into web on a 4-roll laboratory calender. Test boards prepared there-from are measured according to the DIN test methods given in Example 1 Water absorption after 24 hours: 0.3% by weight.
Water absorption after 200 hours: 0.6% by weight.
Water vapour permeability resistance factor: 105,000 ~.

Example 3 Thermoplastic material is prepared under the conditions specified in Example 1 from the components set out below and prepared within the times specified:
Mixing procedure: Time (minutes) introduction of 964 g of EPDM I 0 introduction of 1284 g of SRF black introduction of 268 g of naphth. mineral oil) introduction of 428 g of polyethylene 3 ~density 0.923 g/cm3, melt index 8 g/10 min) ram cleaned 4 discharge 9 The discharge temperature of the material is 155C. Production and testing of the strips is carried out under the conditions specified in Example 1. The water absorption of the test specimens prepared according to the Ex-ample is 0.25% by weight after 24 hours and 0.6% by weight after 200 hours.
The water vapour permeability resistance factor is ~ = 100,000 Example 4 Under the same conditions as in Example 1 the following mixing com-ponents are mixed in the specified times and in the specified proportions to form a thermoplastic material.
Mixing procedure: Time ~minutes) introduction of 1096 g of EPDM I
O
introduction of 261 g of bitumen B 80 introduction of 1253 g of SRF black) introduction of 417 g of chalk introduction of 209 g of polyethylene 3 ~density 0.935 g/cm3, melt index 0.5 g/10 min) ram cleaned 4 discharge 9 The discharge temperature of the material is 160C. The test values for water absorption ascertained under the same conditions as in the previous Examples are 0.3%/0.8% by weight after 24/200 hours. The value 120,000 is determined for the water vapour permeability resistance factor ~.
Example 5 The following mixing components as stated are mixed together under the conditions specified for Example 3:
Mixing procedure: Time (minutes) introduction of 1000 g of EPDM II 0 introduction of 1000 g of SRF black introduction of 450 g of polyethylene 3 ~density 0.923 g/cm3, melt index 8 g/10 min) ram cleaned 4 discharge 9 The EPDM II used here differs from EPDM I by a MLl+4 value of 45 and a polymer crude strength of 50 kp/cm2. The discharge temperature of the material is 158C. Water absorption and water vapour permeability are deter-mined analogously to Example 3. Water absorption after 24 hours is 0.28% by weight and after 200 hours is 0.7% by weight. The water vapour permeability resistance factor is ~ = 114,000.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A thermoplastic composition comprising (a) 100 parts by weight of a polyolefin rubber;
(b) from 15 to 50 parts by weight of a crystalline or partly crystalline polyolefin;
(c) from 30 to 140 parts by weight of a carbon black;
(d) from 5 to 150 parts by weight of a bitumen or mineral oil; and (e) from 3 to 360 parts by weight of chalk or siliceous chalk.

2. A thermoplastic composition according to claim 1, wherein the polyolefin rubber is a polymer of from 15 to 90% by weight of ethylene, from 85 to 10% by weight of propylene and/or butene-(1), and sufficient of a multi-ene to provide from 0.5 to 30 double bonds per 1000 carbon atoms in the rubber.

3. A thermoplastic composition according to claim 1 or 2, wherein the at least partially crystalline polyolefin is a polyethylene having a density of from 0.910 to 0.975 g/cm3, an RSV value (measured at 135°C in decahydronaphthalene) of from 0.5 to 3.3 dl/g and a melt index of from 0.2 to 50 g/10 min.

4. A thermoplastic composition according to claim 1 or 2, which also contains up to one third of the weight of the at least partially crystalline polyolefin of atactic polypropylene and/or polybutene-(1) having a density of 0.86 g/cm3 and an RSV value (measured at 135°C in decahydronaphthalene) of from 0.1 to 3.0 dl/g.

5. A thermoplastic composition according to claim 1 or 2, containing 100 parts by weight of component (a), from 20 to 40 parts by weight of component (b), from 40 to 120 parts by weight of component (c), from 25 to 100 parts by weight of component (d) and from 30 to 300 parts by weight of component (e).