Patent Application
20110272601
The present invention relates to a rapid test for ascertaining the effect of irradiation on the abrasion of a granule, preferably an inorganic or organic granule, particularly preferably a plastic granule.
Plastic granules are a typical form in which thermoplastics are delivered by the raw material producer for the plastics processing industry. Owing to their flowability they are a bulk material, like sand or gravel, and therefore comparatively easy to transport and process further.
Recently, the use of plastic granules as a filler for artificial turf has been discussed intensively. For example, European Patent Application EP 1 416 009 A1 discloses the use of coated rubber particles as litter material or as a loose elastic layer for synthetic turf or other surfacings. The rubber particles are generally shaped irregularly, with n vertices, and preferably have an average size of between 0.4 mm and 2.5 mm up to at most 4.0 mm. The individual rubber particles are provided with a 5 μm to 35 μm thick covering over their entire surface. The covering forms a permanent elastic coating which is intended to substantially prevent the leaching of pollutants, for example zinc. This encapsulation is furthermore intended to reduce a rubbery smell typical of old rubber.
For use as a filler material for synthetic turf, such plastic granules must inter alia have a high abrasion strength. To date, however, there is no known test by which the abrasion strength of plastic granules can be ascertained and assessed rapidly and economically in a straightforward way.
Previously, the so-called Hardgroove test according to ISO 5074 has been carried out in order to test the abrasion strength of synthetic turf granules (infill material). To this end, the plastic granule is ground in a special ball mill (500 revolutions), without any pulverizing or other modifications of the rubber granule being permitted. The particle sizes of the plastic granule before and after grinding are ascertained and compared with one another, an abrasion strength of at least 95% being required in order to pass the test.
This test, however, has many disadvantages:
Occasionally, other abrasion test methods are also used for filler granules, for example using a roller block or ring shear cell. These methods also exhibit substantial disadvantages. It takes a very long time to generate perceptible or measurable abrasion by means of a roller block. Furthermore, it is very difficult or even impossible to quantitatively transfer the fine fraction generated, owing to the large surface area and possibly high electrostatic charging. The equipment is hard to fill and empty, and difficult to thermally regulate in order to be able to measure the abrasion behaviour at different temperatures.
It also takes a very long time to generate perceptible or measurable abrasion by means of a ring shear cell. Quantitative transfer of the material from the apparatus after grinding is difficult, and it is likewise difficult to clean the apparatus. Furthermore, the apparatus can only be thermally regulated with difficulty in order to be able to measure the abrasion behaviour at different temperatures.
The abrasion determination methods (DIN 53516) for plastic blocks and sheets (and therefore for example for coloured material such as EPDM or TPE) are described in DIN V18035-7:2002-06, but cannot be used for abrasion methods on coated used tyre rubber granule.
The same applies to the abrasion test described in DIN ISO 4649 for cylindrical elastomer specimens which are exposed to a defined abrasion stress by means of an emery sheet. This test likewise cannot be used for small-piece granules.
For use as a filler material for synthetic turf, it is furthermore important to find out how the properties of such plastic granules, in particular the abrasion, change under solar irradiation over time (so-called ageing of the plastic granules). To date, however, there is no known test by which the solar irradiation of plastic granules can be simulated and assessed rapidly and economically in a straightforward way, and which makes it possible to determine the effect of irradiation on the plastic granules, in particular on the particle surfaces, within a short time.
Only various treatment methods for the irradiation of the surfaces of coated or uncoated sheets or other two-dimensional surfaces or coated or uncoated particles are known. For example the test, which may furthermore be used for particulate systems, is used to test the effect of UV rays on motor vehicle paint. This employs a container, in which the coated or uncoated particles to be exposed are scattered and then exposed.
As another example of the irradiation of coated or uncoated particles, equipment which operates according to the standard ISO 4892-3 is used by the ISA Sport institute to evaluate the weathering resistance of filler materials for synthetic turf. Here, a coated or uncoated rubber granule is subjected to a climatic simulation in which the sample is exposed to UV light for a period of 125 days.
These tests, however, have various disadvantages which are an obstacle to rapidly estimating the effect of solar irradiation on the properties of plastic granules:
Furthermore, it is important to find out how the colour, the zinc elution and the water retention capacity of such plastic granules change under irradiation. For instance, ascertaining the water retention capacity provides a very good indicator of the suitability of a material as a synthetic turf filler material: the faster the water drains, the sooner the material can be played on again. Particularly in spring and autumn, this parameter is very important because whenever water remains in the bed for a long time, it can freeze and make the pitch no longer playable. Moreover, excessively moist plastic granule is slippery and/or treacherous.
If however it is desirable for water to remain in the bed after watering (for example for cooling, or reducing friction when footballers slide or fall in summer), then filler materials which have a medium to high water retention capacity are preferable.
It was therefore an object of the present invention to provide ways of rapidly testing the effect of irradiation on the abrasion strength of granules, in particular filler materials for synthetic turf.
Furthermore, a rapid test was desired to ascertain the effect of irradiation on the strength and the bonding of material layers on surfaces or interlayers of multilayered granules.
The test should be as rapid and effective as possible to carry out, as widely usable as possible and allow maximally accurate classification of the abrasion behaviour of various granules. In particular, it should be suitable for testing coated rubber particles.
The rapid test should if possible furthermore satisfy the following criteria:
It was also an object of the invention to provide ways for improved simulation of the effect of solar rays on the properties of granules, in particular filler materials for synthetic turf.
When developing coatings of particles, it would be highly advantageous to obtain results as rapidly as possible which can be used in order to test different coatings for their stability in relation to UV irradiation and select the superior coatings.
It would more particularly be advantageous if the UV radiation which strikes the Earth could be used, i.e. in general UV-B and UV-A radiation with a wavelength >295 nm. It would furthermore be more particularly advantageous if primarily UV-B radiation could be used for the testing, since a great deal of damage to coatings results from exposure to UV-B radiation.
The intention was also to find a way of achieving a maximally uniform effect over the entire surface of the granules.
In particular, a solution was desired which
These and other objects, which may be taken from the contexts discussed, are achieved by providing a rapid test having all the features of patent claim 1. Particularly expedient variants of the rapid test are described in the related dependent claims. The protection also includes a granule which has an outstanding property profile and is therefore suitable in particular as a filler material for synthetic turf.
By carrying out a test in which
Furthermore, the procedure according to the invention offers many other advantages:
The test according to the invention is used to rapidly determine the effect of light on the abrasion strength of granules, expediently inorganic or organic granules, preferably plastic granules, particularly preferably coated plastic granules, in particular coated rubber particles which are used inter alia as litter material or as a loose elastic layer for synthetic turf or other surfacings.
The rubber particles are generally shaped irregularly, with n vertices, and preferably have an average size of between 0.4 mm and 4.0 mm. The maximum grain size of the particles is preferably less than 10 mm, particularly preferably less than 7 mm. The minimum grain size of the particles is preferably greater than 0.1 mm, particularly preferably greater than 0.5 mm. The individual rubber particles are preferably provided with a 5 μm to 35 μm thick covering over their entire surface. The covering forms a permanent elastic coating which is intended to substantially prevent the leaching of pollutants, for example zinc. This encapsulation is furthermore intended to reduce a rubbery smell typical of old rubber. Further details of such plastic granules may be found, for example, in European Patent Application EP 1 416 009 A1.
The test according to the invention is capable in particular of distinguishing well between different coatings. For instance, the quality of coloured coatings may be evaluated by stronger or weaker coloration of the wall of the cutting mill after carrying out the abrasion test. The degree of coloration of the mill wall may, for example, be determined by visual comparison with various reference colorations. As an alternative, other suitable methods may also be used to determine adhesions on the mill wall, in order to establish the extent to which curing of layers has progressed, which is advantageous in particular for colourless coating systems.
Furthermore, the test according to the invention may also be used in order to evaluate the binding of a material composite. To this end particles which have been obtained from the material composite, and have preferably been cut, stamped or broken from the material composite, are preferably studied.
The rapid test according to the invention comprises the steps of
The determination of the abrasion strength includes the following steps:
First, an attempt is made to comminute the granule at least partially by grinding. To this end, in the scope of the present invention, a cutting mill is used which conventionally consists of a horizontally or vertically arranged rotor that is equipped with blades, which in the scope of a first particularly preferred embodiment of the present invention work against blades anchored in the housing of the mill. A schematic diagram of such a mill is given in Römpp Lexikon Chemie, editors: J. Falbe, M. Regitz, 10th edition, Georg Thieme Verlage, Stuttgart, N.Y., 1998, volume: 4, keyword: “Mühle”, page 2770. For further details, reference is therefore made to this publication and the cited literature references.
In the scope of a second particularly preferred embodiment of the present invention, the housing of the mill does not comprise anchored blades, so that the ground granule can be removed more easily from the housing.
The working principle of the cutting mill is preferably cutting/impact.
The intensity of the grinding can be controlled via the energy exerted by the mill. In the scope of the present invention, it is preferable to use cutting mills which exert a cutting mill energy in the range of from 10 W to 400 W, particularly in the range of from 50 W to 300 W.
The rotation speed of the cutting mill preferably lies in the range of from 100/min to 30,000/min, particularly in the range of from 1000/min to 25,000/min.
The circumferential speed of the cutting mill preferably lies in the range of from 10 m/s to 100 m/s, particularly in the range of from 20 m/s to 80 m/s.
The dimensioning of the mill may in principle be selected freely and adapted to the requirements of the particular case. Expediently, the grinding chamber of the cutting mill is filled to at least 10% during the grinding, expressed in terms of the maximum working volume of the cutting mill.
The cutting mill and the cutting tool are preferably made of a material which is harder than the granule to be studied. It has proven particularly suitable to use grinding chambers and cutting blades made of stainless steel, in particular stainless steel 1.4034.
In the scope of the present invention, the material to be ground is preferably placed in the chamber of the cutting mill and sheared by a stainless steel beater for a predetermined stressing time (“grinding time”). This gives rise to mutual friction, impact and cutting of granules or layers on the granules. Owing to the large-scale and complex nature of the shearing, a rapid test is achieved for the abrasion stability of granules, in particular coated plastic granules. The results of the test are affected above all by the following variables:
The results are also affected by the duration of the grinding. For the purposes of the present invention, it is preferable to select grinding times in the range of from 5 seconds to 10 minutes, particularly in the range of from 5 seconds to 150 seconds.
The grinding force of the cutting mill may act continuously or discontinuously. A procedure in which the grinding force is preferably not varied during the grinding has proven suitable.
If need be, the grinding chamber of the cutting mill may be thermally regulated during the grinding, in particular heated or cooled, in order to obtain information about the abrasion behaviour of the granules at different temperatures. Thermal regulation which changes in the course of the grinding may also be envisaged. To this end a suitable thermally regulated liquid, for example water, is preferably introduced into the heating/cooling chamber of the grinding chamber.
Grinding mills suitable for the purposes of the present invention are commercially available. The following mill has proven more particularly suitable:
After grinding, the particle size distribution of the ground product is ascertained by screening analysis, a procedure in accordance with DIN 53 477 (November 1992) preferably being adopted.
It is preferable to use round analysis screens (referred to as screens for short) whose screening frame preferably consists of metal. The screens preferably have a rated diameter of 200 mm. The screening cover, including the screening frame and the screening pan, preferably fit onto or into one another so as to create a seal. Metal wire fabric according to DIN ISO 3310 Part 1 is preferably stretched over the screens. In many cases, a screening set of 6 screens with metal wire fabric (mesh width: 63 μm, 125 μm, 250 μm, 500 μm, 1 mm, 2 mm) is sufficient. For the purposes of the present invention, it is particularly preferable to use a screening set which comprises a 500 μm screen and a bottom.
Mechanical screening aids, such as rubber cubes, are not recommendable owing to the risk of vitiating the results and damaging the screen having metal wire fabric.
Selection of the plane screening machine is preferably used to ensure that separation into grain fractions, corresponding to the screened material, is completed after 15 minutes. The separation is preferably achieved by a horizontal circular movement of the screening set with a rotation frequency of preferably 300+−30 min−1 and an amplitude of 15 mm.
The screening is preferably carried out discontinuously, particularly preferably in a plurality of intervals, more particularly preferably in from 3 to 10 intervals, particularly in 5 intervals. The intervals are preferably of equal length and expediently last from 1 minute to 5 minutes, in particular 3 minutes. After each interval, the screening is preferably interrupted and then restarted again. This may optionally be programmed on the screening machine.
Screening machines suitable for the purposes of the present invention are commercially available. The following screening machine has proven more particularly suitable:
The particle size distribution is ascertained in a manner known per se by weighing out the screen.
The result of the screening analysis is compared with at least one reference value, in order to classify the abrasion of the granule.
In this case, the ascertained particle size distribution of the ground product is preferably compared with the result of at least one other granule, in order to classify the abrasion of the granules in comparison with the other granule.
In the scope of another preferred embodiment of the present invention, the ascertained particle size distribution of the ground product is compared with the particle size distribution of the underground educt, in order to categorize the abrasion of the granule being studied.
In the scope of a third preferred embodiment of the present invention, the ascertained particle size distribution of the ground product is compared with at least one predetermined threshold value, in order to categorize the abrasion of the granule being studied.
Moreover, for the purposes of the present invention the fraction of particles smaller than 500 μm has in particular proven to be a particularly suitable criterion for evaluating the abrasion of the particles.
In the scope of a particularly preferred variant of the present invention, the walls are checked after the grinding for possible deposits which have been caused by the shearing of the granule in the cutting mill. By optional comparison (for example with suitable reference samples, references, reference scales), it is generally possible to assess or rank the strength and the bonding of material layers on surfaces or in interlayers of multilayer granules.
For the inventive irradiation of the granules, the granules are arranged in a sample container and irradiated with an irradiation lamp, the granules being blended periodically during the irradiation so that different surfaces of the granules are irradiated.
The term “periodically” in this context refers to an action (here blending) recurring regularly at equal intervals, repetition of at least 2 processes, preferably at least 5 processes, in particular at least 10 processes being preferred here.
The repetition rate of the action (here blending) is preferably at least 1 process per minute, preferably at least 5 processes per minute, in particular at least 10 processes per minute. In the scope of a particularly preferred embodiment of the present invention, continuous blending is carried out during the irradiation.
The term “blending” in the scope of the present invention refers to thorough mixing of the granules. This preferably leads to a change in the three-dimensional orientation of at least two granules, preferably at least 5 granules, in particular at least 10 granules. Furthermore the mutual relative positions of at least two granules, preferably at least 5 granules, in particular at least 10 granules, are preferably changed.
In the scope of a particularly preferred embodiment of the present invention, the granules are blended so that at least two different surfaces, preferably at least three different surfaces of the granules are irradiated successively, each of these surfaces being irradiated at least twice, preferably at least five times, in particular at least 10 times.
Owing to the periodic blending of the granules, the irradiation method according to the invention differs from the known irradiation methods in which the granules are not blended during the irradiation and only one surface of the granules is irradiated continuously.
The method according to the invention leads to very uniform irradiation of the entire surface of the granules. The irradiation is preferably carried out in such a way that the difference between the shortest irradiation time of a surface of the granules and the longest irradiation time of a surface of the granules is at most 100%, preferably at most 50%, in particular at most 20% of the longest irradiation time of a surface of the granules.
The irradiation simulates the effect of light, in particular sunlight, on the granules. The light therefore preferably comprises components of natural sunlight; the irradiation is preferably carried out with a wavelength in the range of from 1 nm to 1000 nm, preferably with a wavelength in the range of from 200 nm to 400 nm (so-called near UV radiation), in particular with a wavelength in the range of from 295 nm to 350 nm (so-called UV-B radiation).
For the purposes of the present invention, it is particularly advantageous to use a device according to the invention for irradiating granules. This device comprises
The position of the irradiation lamp relative to the sample container may in principle be selected freely, the irradiation lamp preferably being arranged inside the sample container. It may however also be arranged outside the sample container, although this variant is less preferred.
Direct action of the rays on the granule to be irradiated is furthermore preferred. Materials which can partially or fully absorb or deviate the light from the irradiation source are therefore to be avoided if possible on the line of sight between the irradiation lamp and the granule. This is unless undesired radiation, for example IR radiation (heat radiation) is intended to be reduced by special materials, for example filters, together with the best possible transparency for UV-B radiation.
The irradiation lamp is preferably surrounded by inert gas flushing, which is preferably arranged between the irradiation lamp and the sample container. Inert gases which are particularly suitable for the purposes of the present invention comprise in particular nitrogen and all noble gases, such as helium and neon.
In the scope of a particularly preferred embodiment of the present invention, the granules in the sample space are furthermore flushed with at least one gas and/or at least one liquid in order to study the effect of the gas and/or the liquids on the properties of the granule during the irradiation. Air, water vapour, acidic water vapour, acid rain and water are particularly suitable for these purposes.
The irradiation lamp is furthermore preferably provided with a filter, which filters out IR radiation (780 nm to 1 mm) at least partially from the radiation spectrum of the irradiation lamp. To this end, the irradiation lamp is preferably surrounded by a quenching space which comprises an IR quenching liquid and is preferably arranged between the irradiation lamp and the sample container, particularly preferably between the inert gas flushing and the sample container.
IR quenching liquids particularly suitable for the purposes of the present invention comprise all liquids which are fluid under the study conditions and at least partially absorb light in the range of from 780 nm to 1 mm.
The use of an IR filter substantially avoids heating of the granules during the irradiation.
Likewise, the shape of the sample container is not subject to any particular limitations. Nevertheless, sample containers with a region which comprises a straight cylindrical shape have proven suitable, the irradiation lamp preferably being arranged centred in the middle of the cylinder.
In the scope of a particularly preferred embodiment of the present invention, the irradiation lamp has an elongate shape, the alignment of the irradiation lamp preferably corresponding to the principal axis of the sample container, in particular the principal axis of the straight cylindrical part of the sample container.
The inner wall of the sample container preferably comprises a reflective material in order to direct the light, which has for example not struck the granules or has travelled past them, after reflection onto the granules. The effectiveness of the irradiation can be increased significantly in this way. In this context, particularly suitable reflective materials lead to reflection of at least 5%, preferably at least 25%, particularly preferably at least 50% of the incident radiation. Steel is a material which is particularly suitable for this purpose.
Preferably, at least 80% of the total inner surface of the sample container is coated with the reflective material and/or consists of it.
In the scope of a particularly preferred embodiment of the present invention, the sample container furthermore comprises a material having a high thermal conductivity, preferably a thermal conductivity of more than 1 W/(m·K), in particular more than 3 W/(m·K), measured at 25° C.
Preferably, at least 80% of the sample container consists of a material having a high thermal conductivity.
The device of the present invention preferably also comprises at least one temperature control element, preferably a heating or cooling element, in particular a cooling element, which makes it possible to irradiate the plastic particles under fixed predetermined temperature conditions or in fixed predetermined temperature ranges.
The sample container furthermore preferably comprises a mixing element for mixing the granules during the irradiation. Flow baffles, which partially deviate the movement of the granules during rotation of the container along its principal axis, have proven particularly suitable in this context.
In order to increase the effect of blending the granules, the head and/or foot end, particularly preferably the head and foot ends, of the sample container are preferably canted so as to blend granules even more strongly during the irradiation. In this case, the inner diameter of the sample container preferably decreases in the direction of the canted end.
The size of the sample container is of secondary importance. The sample container is preferably dimensioned so that it can hold between 10 g and 500 kg of granules. Sample containers which are more particularly suitable for the purposes of the present invention have a holding capacity in the range of from 1 kg to 10 kg.
During the irradiation, the sample container is preferably filled with granules to from 0.1% to 10%, preferably to from 0.5% to 5%, expressed in terms of the total volume of the sample container.
In the scope of the present invention, the sample container is preferably rotated in order to achieve blending of the granules. The rotation is preferably carried out about a principal axis of the container, the irradiation lamp preferably also being positioned along its principal axis.
The rotation speed is preferably in the range of from 1 rpm to 500 rpm.
The structure of an irradiation apparatus which is particularly suitable for the purposes of the present invention is shown schematically in
The sample container (2) has a straight cylindrical shape with canted head and foot ends (7), the inner diameter of the sample container (2) decreasing in the direction of the canted ends (7).
The sample container (2) is preferably made of a thermally conductive steel, which reflects at least 5% of the incident radiation.
The irradiation lamp is surrounded by inert gas flushing (4), which is arranged between the irradiation lamp (3) and the sample container (2).
The irradiation lamp (3) is furthermore surrounded by a quenching space (5), which comprises an IR quenching liquid and is arranged between the inert gas flushing (4) and the sample container (2).
The device comprises a temperature control element (1), preferably a cooling water bath, for thermally regulating the sample container (2) in the course of the irradiation.
During the irradiation, the sample container (2) is rotated preferably continuously about the principal axis of the sample container (3), along which the irradiation lamp (3) is positioned.
The temperature during the irradiation may in principle be selected freely, and in particular matched to the conditions which are intended to be simulated or reproduced. For the purposes of the present invention, however, the temperature preferably lies in the range of from 0° C. to 95° C.
The intensity of the irradiation of the granules can be controlled via the duration of the irradiation and the irradiation strength. The irradiation is preferably carried out for each time in the range of from 1 h to 1000 h, particularly in the range of from 24 h to 500 h. The irradiation of the granules is furthermore preferably carried out with an irradiation strength in the UV-B band in the range of from 1 W/m2 to 10,000 W/m2, particularly in the range of from 100 W/m2 to 1000 W/m2.
In the scope of a particularly preferred variant of the rapid test according to the invention, the colour properties of the granules are furthermore studied before and after the irradiation. The colour measurement is preferably carried out in accordance with DIN 5033.
Furthermore, the zinc elution of the granules is preferably studied before and after the irradiation. The measurement of the zinc elution is preferably carried out in accordance with the prestandard DIN V 18035-7, 6.11.3 (Sports Grounds, Part 7: Synthetic Turf Areas). In particular, the following procedure has proven suitable:
In order to determine the concentration of heavy metals, 100 g of granules in a flask with a CO2 feed instrument are eluted with 1 l of deionized water (granule to water as 1:10) with a constant delivery of CO2 gas (about 50 ml of CO2/min) for 24 h. The eluate is filtered off through a glass filter (acid wash, 0.3 μm to 1 μm) (1st eluate). The same sample is then subjected to a second elution for 24 h (2nd elution: 24 h to 48 h, so-called acid 48 h eluate), and the eluate is filtered off. In order to dislodge the adhering gas bubbles, the flask is shaken occasionally during the elution (optionally with a vibrating table).
The heavy metal concentrations determined in the acid 48 h eluate are preferably used for the evaluation.
In the scope of a particularly preferred variant of the rapid test according to the invention, the water retention capacity of the granule is furthermore studied before the irradiation. It is furthermore particularly preferable to determine the water retention capacity of the granule after the irradiation.
In order to determine the water retention capacity, the following procedure has proven particularly suitable in this context:
In a plastic cylinder (Dinner=27 mm, H=160 mm) whose lower side is provided with a gauze fabric (mesh width about 0.4 mm), an approximately 40 mm high bed of the sample is introduced. The cylinder is fitted on a balance and immersed into a water container in order to cover the granule bed with a liquid (about 10 mm clearance). In order to wet the sample with fully deionized water, the sample and water are stirred after the 1st immersion.
The granules may possibly be difficult to wet with water. In such a case, the air bubbles cannot be fully removed after filling with water.
After removing the water container, the mass change of the cylinder with the sample is recorded (measurement interval 1 s). In each case, 2 beds are measured 2 times. The measurement values of a dummy test (empty cylinder) are subtracted from the recorded measurement values, and the result is expressed in terms of the dry sample mass (mass of the wet sample divided by the mass of the dry sample).
The described test for determining the water retention capacity can be carried out rapidly and requires only little sample material. The purpose of the study with this test is to evaluate how much water is retained by a particle bed after a short draining phase.
In particular, the response of synthetic turf with filler material to heavy rain is very important for the application. If a synthetic turf system allows rainwater to flow away very rapidly, then for example even strong rain interferes little or not at all with football matches, compared with a synthetic turf system which does not allow water to drain very rapidly.
Because the filler material bed has a great effect on this, the test developed for the water drainage behaviour allows very rapid and simple assessment or ranking of different filler materials in respect of their water drainage behaviour and therefore the playability in rainy weather.
Coated rubber particles having the following properties have proven more particularly suitable as filler materials for synthetic turf:
These values refer to measurements according to the methods described in the experimental part.
The invention will be further illustrated below by several examples, without thereby intending to restrict the concept of the invention.
A device with a schematic structure according to
In a glass beaker, 100 g of the coated or uncoated sample to be irradiated were weighed out and introduced into the reactor. The immersion tube with the UV radiator was then installed in the holder provided for this purpose. The nitrogen flow rate was set at 6 l/h, and the cooling water flow rate at 100 l/h. The UV exposure apparatus was then turned on, and the motor which provided the reactor rotation (12 rpm) was started.
The coated or uncoated sample to be studied was then irradiated for 240 hours with a 1.55 kW radiator power (wavelength of the radiation to which the sample was exposed in the UV range: 295-380 nm) under rotation.
After the irradiation had been completed, the apparatus was turned off and the irradiated coated or uncoated sample was removed quantitatively from the reactor.
The sample was subjected to the following tests, in order to study the effect of the UV irradiation.
In its intensity in the UVB range, the described UV test was approximately 360 times stronger than natural sunlight in summer at noon in Germany through 24 hour continuous irradiation. A radiator power of 1.55 kW gave the following powers for the UVA and UVB ranges:
The drum dimensions provided an irradiated area of 1687 cm2, which means an irradiation strength of 439 W/m2 for the UVB range.
In order to obtain the results, the following procedure was adopted:
First the colour, the abrasion and the zinc elution of the unirradiated product were measured. Next, a specimen of a product was respectively subjected to the UV irradiation in the UV irradiation apparatus, the irradiated product was removed as quantitatively as possible from the apparatus and in each case subjected to a further test or all the tests: either zinc elution or colour measurement or abrasion or water retention capacity, or all the tests indicated.
The difference [values of the study after UV irradiation] minus [values of the study before UV irradiation] gives a Delta value whose magnitude and sign described the effect of the UV irradiation on the material tested.
The zinc content was determined according to the prestandard DIN V 18035-7, 6.11.3 (Sports Grounds, Part 7: Synthetic Turf Areas).
The colour measurement was determined in accordance with DIN 5033.
The water retention capacity was ascertained according to the test described above.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2009-000179.4 | Jan 2009 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP09/67981 | 12/29/2009 | WO | 00 | 7/13/2011 |
