COMPOSTABLE TURF WITH DECOMPOSITION INHIBITOR

Abstract

The invention relates to a completely or partially compostable turf (202, 300) the turf being a completely or partially compostable artificial turf or a hybrid turf (202) comprising a completely or partially compostable hybrid turf support, the turf comprising a decomposition inhibitor, the decomposition inhibitor in the turf being adapted to lose its functionality or leave the turf until a defined period of time has elapsed.

Claims

1. A method of controlling decomposition of an artificial turf installation, the method comprising: providing an artificial turf installation including a compostable turf comprising compostable synthetic fibers and a compostable carrier structure, adding a decomposition inhibitor on the turf, the decomposition inhibitor having a decomposition-inhibiting functionality for a defined period of time reducing decomposition of the compostable turf by microorganisms.

2. The method of claim 1, wherein the decomposition-inhibiting functionality of the decomposition inhibitor is designed to expire when the defined period of time has elapsed.

3. The method of claim 1, wherein the decomposition inhibitor is configured to leave the turf when the defined period of time has elapsed.

4. The method of claim 1, further comprising adding a decomposition booster to the turf, the decomposition booster being adapted to compost the turf.

5. The method of claim 4, the decomposition booster being added in temporal proximity to an expiration of the defined period of time.

6. The method of claim 4, further comprising: prior to adding the decomposition booster removing the compostable turf from the artificial turf installation and dividing the compostable turf into pieces.

7. The method of claim 1, wherein the compostable turf comprises artificial turf fibers comprising polylactic acid, and a compostable carrier mesh made of fibers derived from plant material, in particular sisal, jute, linen, coconut, or hemp.

8. The method of claim 1, wherein the compostable turf comprises a backing of natural latex, or starch-based latex, or agar-agar

9. The method of claim 4, wherein the decomposition booster comprises an acidic solution having a pH value below 6, more preferentially below 4.5.

10. The method of claim 4, wherein the decomposition booster comprises: soil, or one or more strains of isolated soil bacteria, in particular bacteria isolated from compost, in particular hydrocarbon-degrading bacteria, in particular one or more bacterial strains selected from the group comprising Pseudomonas sp., Mucobacterium sp., Corynebacterium sp., Aeromonas sp., Rhodococcus sp., and Bacillus sp.

11. The method of claim 4, wherein the decomposition booster comprises enzymes adapted for biodegradation of the compostable turf.

12. The method of claim 1, wherein the decomposition inhibitor comprises an antimicrobial substance, including a HALS-light stabilizer or triclosan or a substance having a porous surface structure adapted to impede the growth of microbes by adsorbing the microbes to the porous surface.

13. The method of claim 1, wherein the decomposition inhibitor comprises at least one of a silver compound, an organoiodide compound, and an organobromide compound, including bromides and iodides of alkyl, aryl, alkenyl, alkynyl, arylalkyl, arylalkenyl, or arylalkynyl groups.

14. An artificial turf comprising: compostable synthetic fibers, a compostable carrier structure, and a decomposition inhibitor having a decomposition-inhibiting functionality for a defined period of time reducing decomposition of the compostable synthetic fibers and of the compostable carrier structure by microorganisms.

15. The artificial turf of claim 14, wherein the decomposition-inhibiting functionality of the decomposition inhibitor is designed to expire when the defined period of time has elapsed.

16. The artificial turf of claim 14, wherein the decomposition inhibitor is configured to leave the turf when the defined period of time has elapsed.

17. The artificial turf of claim 14, further comprising decomposition booster added to the turf, the decomposition booster being adapted to compost the turf.

18. The artificial turf of claim 17, wherein the decomposition booster is added in temporal proximity to an expiration of the defined period of time.

19. The artificial turf of claim 14, wherein compostable synthetic fibers comprise polylactic acid, and the compostable carrier structure is a mesh structure comprising fibers derived from plant material including sisal, jute, linen, coconut, or hemp.

20. The artificial turf of claim 14, further comprising a backing of natural latex, or starch-based latex, or agar-agar; and wherein the decomposition booster comprises at least one of: an acidic solution having a pH value below 6, more preferentially below 4.5, or a strain of isolated soil bacteria including bacteria isolated from compost, hydrocarbon-degrading bacteria, in particular one or more bacterial strains selected from the group comprising Pseudomonas sp., Mucobacterium sp., Corynebacterium sp., Aeromonas sp., Rhodococcus sp., and Bacillus sp., or an enzyme adapted for biodegradation of the turf or turf components.

21. The artificial turf of claim 14, wherein the decomposition inhibitor comprises an antimicrobial substance, including a HALS-light stabilizer or triclosan or a substance having a porous surface structure adapted to impede the growth of microbes by adsorbing the microbes to the porous surface.

22. The artificial turf of claim 14, wherein the decomposition inhibitor comprises at least one of a silver compound, an organoiodide compound, and an organobromide compound, including bromides and iodides of alkyl, aryl, alkenyl, alkynyl, arylalkyl, arylalkenyl, or arylalkynyl groups.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0111] In the following, embodiments of the invention are explained in greater detail, by way of example only, making reference to the following drawings:

[0112] FIG. 1 is a flow chart of a method for controlling decomposition of artificial or hybrid turf.

[0113] FIG. 2A depicts a piece of artificial or hybrid turf installed at a use site on top of a sand or aggregate layer.

[0114] FIG. 2B depicts a piece of artificial or hybrid turf installed at a use site on top of a sand or aggregate layer.

[0115] FIG. 2C depicts a mixture comprising pieces of chopped artificial or hybrid turf and soil.

[0116] FIG. 3 depicts a piece of hybrid turf.

[0117] FIG. 4 shows a plot illustrating the provision of the inhibitor and the booster.

[0118] FIG. 1 is a flow chart of a method for controlling the decomposition of artificial or hybrid turf. For example, the owner or operator of a sport field that is used for playing soccer may intend to install hybrid turf in the use site. He or she may intend to use the installed hybrid turf for at least six months.

[0119] In step 102, artificial turf or hybrid turf comprising a decomposition inhibitor whose functionality or presence in the turf material is limited to a defined period of time is provided. For example, the operator may order a particular hybrid turf that comprises a particular amount and composition of a decomposition inhibitor that ensures thatalthough the hybrid turf may completely or partially consist of compostable materialthe composting will not start until a defined time of e.g. five or six months has elapsed since the turf was installed at the use site.

[0120] The amount of decomposition inhibitor may depend on the particular use case scenario and the minimum life expectancy respectively required. For example, a typical football season has a duration of five month and the typical usage time of hybrid turf as a golf green is six month.

[0121] For example, the ordered and delivered artificial or hybrid turf is installed at the use site as shown in FIG. 2A, which depicts a piece of artificial or hybrid turf installed at a use site on top of a sand layer.

[0122] During the defined time period of e.g. six months, the operator in step 104 may repeatedly expose the turf to water. Optionally (e.g., if it is hybrid turf), a fertilizer can be added to the turf. The water and/or the fertilizer may comprise a decomposition inhibitor (e.g., chitosan) that provides additional protection against biodegradation.

[0123] After the six months have passed, the hybrid turf will have lost its decomposition inhibitor, and/or the decomposition-inhibiting effect of said inhibitor, completely or almost completely. For example, bactericide substances may have diffused out of the turf and may be washed away by rainfalls and irrigation. Alternatively, the bactericide substance may be an adsorbent that is filled to its capacity with bacteria and other small particles. Thus, after six months, the turf may slowly begin to decay. In case the operator has decided to replace the worn turf, the operator may in addition add, in step 106, a decomposition booster, such as moist soil with soil bacteria, or enzymes, to the turf. As a consequence, the turf will decay rapidly and turn into CO2, water, and minerals, and optionally compost within six further months starting from the adding of the decomposition booster.

[0124] The adding of the decomposition booster may not be necessary in every case. For example, in case the artificial turf or hybrid turf is installed on top of natural soil in a humid and warm climate, the composting of the turf may start immediately after the predefined time (here: six months) has elapsed and the decomposition inhibitor has lost its function. Thus, by using a compostable turf with a decomposition inhibitor and, optionally, with a decomposition booster after the defined period of time has elapsed, a very precise control over the composting process may be achieved.

[0125] FIG. 2A depicts a piece of artificial or hybrid turf 202 that has been installed at a use site on top of a sand or aggregate layer 204. The layer 204 may have, for example, a thickness of 1 cm or more. The hybrid turf may have, for example, a thickness of 3-15 cm. The sand or aggregate may be added on top of a base material 206 (e.g., concrete, soil, or a further layer of sand). The sand or aggregate layer 204 may ensure that rain water can leave the turf, that the total elasticity of the turf lawn is increased, that irregularities in the base layer are leveled out, and that the soil comprising soil bacteria does not come into contact with the turf. Thus, once the decomposition inhibitor has turned inactive, the composting of the turf may still not start, because sand lacks a sufficient amount of soil bacteria and moisture. However, by supplementing the turf with a decomposition booster, the composting of the turf may be triggered at a defined time that suits the needs of the sport field operator.

[0126] FIG. 2B depicts the pavement structure generated by chopping the turf 202 into pieces and mixing the turf pieces with soil 214 to generate a layer 208 comprising at least 10% soil, preferably 20% or more preferably more than 50% soil. The soil 214 can be derived from a different region and transported to the use site as indicated in FIG. 2B. Alternatively, the sand/turf mixture may be transported to a composting facility where this mixture is supplemented with soil 214 and is maintained under composting conditions, in particular a humid and warm environment.

[0127] FIG. 2C depicts a situation where the chopped pieces of the turf 202 depicted in FIG. 2A aretogether with the sand/aggregate layer 204ploughed into the base layer 212 consisting of soil to a defined depth. The turf is chopped into pieces and is ploughed together with the sand layer 204 into the base layer 206 consisting of soil. Thereby, the turf material comes into contact with the soil bacteria, and the composting of the turf pieces starts. The ploughing depth determines the fraction of soil contained in the mixture 210 of sand, turf pieces, and soil generated during the ploughing process.

[0128] FIG. 3 depicts a piece of hybrid turf 300 having been installed at the use site. The base layer 314 at the use site may be, for example, clay or any other form of soil comprising soil bacteria. On top of the base layer is a layer of sand or aggregate 304. The hybrid turf installed on top of the sand or aggregate layer comprises a compostable carrier structure 305 (e.g., a jute mesh) and compostable fibers 310 (e.g. of polylactic acid) incorporated into the carrier structure by, for example, tufting, knitting, or weaving. The fibers can be, for example, monofilaments or bundles of multiple monofilaments. Each monofilament can be generated, for example, in an extrusion process or by means of a slit film process. In order to firmly fix the fibers 310 in the carrier at least until the hybrid turf is transported from the sod farm to the use site, a backing 302 is applied to the lower side of the carrier structure 305 such that at least some portions of the fibers become embedded in the backing. When the liquid backing solidifies, the fibers are mechanically fixed in the carrier. The roots 308 of the plants may reach the sand and even the base layer 214. In FIG. 3, the natural grass fibers 312 are depicted in black, and the artificial turf fibers 310 in grey. The natural grass blades intermix with the artificial turf fibers and form a piece of hybrid turf 300. When the natural grass has reached its desired length, the backing 302, which is preferably free of the decomposition inhibitor, has preferably already disintegrated into small fragments and may even have been largely or completely degraded without a negative impact on the stability of the hybrid turf. An optional fill layer 306 supports the roots and crowns of the natural grass plants, and the grass blades of the natural grass plants, as well as a large portion of the artificial turf fibers 310, extend above the fill layer to create a hybrid grass surface that faithfully reproduces a natural grass surface. The support carries the natural grass plants and the fill layer and stabilizes it during transport from the sod farm to the use site and in the early phase of growing the natural grass.

[0129] According to embodiments, the backing 302 may comprise agar-agar, starch, or a heterogeneous latex mixture whose various latex types have different swelling capabilities. Thus, when the backing 302 is in contact with water, it is dissolved or mechanically disrupted. As a consequence, the roots have sufficient space to grow without clogging the openings of the carrier mesh 305 and thus without making the hybrid turf support structure water-impermeable.

[0130] According to embodiments, the hybrid turf is generated such that the liquid backing is applied to the lower side of the carrier structure 305. The carrier structure can be a multilayer structure, for example, a combination of a jute mesh and a PLA mesh. The backing is applied such that more than 10% but less than 70%, and preferentially less than 50%, of the lower side of the whole carrier structure 305 is sealed by the backing. According to embodiments, the backing of artificial turf is also generated so that it does not completely seal the carrier structure for the artificial turf fibers. This may prevent an accumulation of water, which could cause the roots of the natural grass plants to rot (in the case of hybrid turf), or could result in a premature degradation of the turf due to prolonged contact with water (in both the cases of hybrid turf and artificial turf).

[0131] According to some embodiments, the liquid backing is made of a degradable material (e.g., a biodegradable material). For example, the liquid backing can be made of natural latex or starch-based latex: the liquid backing can be a copolymer of starch with styrene/butadiene latex. Alternatively, the biodegradable backing can be made of natural rubber.

[0132] According to other embodiments, the degradable backing essentially consists of or comprises (e.g., by at least 30% or more) a biodegradable material. For example, the biodegradable backing can comprise a copolymer of starch with styrene-butadiene latex. The generation of said copolymers is described, for example, in US20130276245A1, but embodiments of this invention differ from the method described in US20130276245A1 at least in that no pigments are used. For example, the starch-latex copolymer backing can be made from a mixture comprising starch and monomeric components. The monomeric components in the mixture that are copolymerized comprise: [0133] styrene or a substituted styrene; [0134] an acrylate and/or methacrylate; [0135] optionally: one or more further ethylenically unsaturated monomers.

[0136] For example, 5 to 40% by weight of the mixture may consist of starch, and 50 to 95%, preferably 60 to 95%, by weight of the mixture may consist of the monomeric components. The starch is biodegradable and also will allow the roots to penetrate the carrier structure mesh cells that are fully or partially sealed by the starch-latex copolymer backing after some weeks or months.

[0137] FIG. 4 shows a plot which illustrates the provision of the inhibitor and the booster. At time to, an artificial turf or hybrid turf comprising a particular, initial concentration of the decomposition inhibitor is provided. For example, at time t.sub.0, an artificial turf or hybrid turf may be installed at a use site, whereby the material of the turf comprises a defined concentration c.sub.0 of the decomposition inhibitor. Alternatively, at time t.sub.0, an artificial turf or hybrid turf may be installed at a use site, whereby the material of the turf does not comprise the decomposition inhibitor. However, immediately or several days after the installation of the turf, a defined concentration c.sub.0 of the decomposition inhibitor is applied on the turf, e.g. as a component of the water used for irrigating the turf. The concentration of the inhibitor is chosen such that during a defined period of time, e.g. 6 month or 12 month, the inhibitor continuously loses its function or leafs the turf. For example, the inhibitor can be a porous material whose surface binds bacteria until the binding capacity of the porous material is exhausted. Alternatively, the inhibitor can be material that gradually decays or that is gradually washed out of the turf. The nature and concentration of the decomposition inhibitor in the turf is chosen such that it loses its decomposition-inhibiting functionality or leaves the turf until the defined period of time ppt has elapsed at t.sub.1. This may ensure that after the time t1 a rapid composting process can be triggered by adding a decomposition booster at time t.sub.2. Preferably, the decomposition booster is added in close temporal proximity to time t.sub.1. Thus, t.sub.2 and t.sub.1 may typically be identical or very similar. This may ensure that the turf remains stable until time t.sub.1 is reached, but may degrade rapidly when the decomposition booster is added, e.g. when the turf is mechanically disassembled and mixed with the decomposition booster, e.g. soil.

LIST OF REFERENCE NUMERALS

[0138] 1. 100-106 steps [0139] 2. 202 hybrid or artificial turf [0140] 3. 204 sand or aggregate layer [0141] 4. 206 base material layer [0142] 5. 208 sand/soil/turf pieces mixture [0143] 6. 210 sand/soil/turf pieces mixture [0144] 7. 212 soil [0145] 8. 214 soil [0146] 9. 300 hybrid turf [0147] 10. 302 backing (disrupted) [0148] 11. 304 sand or aggregate layer [0149] 12. 306 filler material [0150] 13. 308 roots [0151] 14. 310 artificial turf fibers [0152] 15. 312 natural grass blades [0153] 16. 314 soil layer/base layer