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EP-4739749-A1 - RUBBER MULCH

EP4739749A1EP 4739749 A1EP4739749 A1EP 4739749A1EP-4739749-A1

Abstract

The invention relates to rubber mulch for use as ground cover to improve moisture conditions of a landscape, said mulch containing pieces of hydrophilic modified rubber mixed with pieces of hydrophobic modified rubber in a weight ratio of 10:90 to 90:10, further it relates to the method of their production and the processing line and production units for such method.

Inventors

  • Heinige, Pavel
  • ESLAMIGHAYOUR, Hamid

Assignees

  • Heinige, Pavel
  • Eslamighayour, Hamid

Dates

Publication Date
20260513
Application Date
20230704

Claims (17)

  1. A rubber mulch for application as ground cover, characterized in that said rubber mulch contains pieces of hydrophobic modified rubber mixed with pieces of hydrophilic modified rubber in a weight-to-wight ratio from 10:90 to 90:10, preferably 40: 60 to 60:40.
  2. A rubber mulch according to claim 1, characterized in that said rubber pieces have and at least two different lengths in the range from 30 to 150 mm, and preferably width from 5 to 50 mm.
  3. A rubber mulch according to claim 1 or 2, characterized in that the rubber pieces have an increased surface area, for example by corrugation.
  4. A method of producing the rubber mulch according to any one of claims 1 to 3, characterized that in step a) a devulcanized rubber material is obtained and then at least two batches of rubber material are processed by consecutive steps from b) to h), which differ in step f) for each of the batches in the type of grafting solution, and finally said batches are mixed together in step i); whereas the steps from b) to i) are as follows: step b) forming a homogeneous rubber compound by mixing said devulcanized rubber material with at least a vulcanizing agent and a vulcanization activator; step c) creating a rubber band (9) with a bottom surface and a top surface by extruding the homogenous rubber compound from step b) at a temperature from 100°C to 180°C and pressure from 1 MPa to 100 MPa through a die of the extruder; step d) cooling down of the rubber band (9); step e) creating a reactive surface on the rubber band (9) by pre-irradiating the bottom surface and the top surface of the rubber band (9) with a defined dose of radiation, for example with an electron beam at an accelerator voltage of 130 to 170 kV and a dose value of of 25 to 40 kGy; step f) grafting by immersing each batch in a grafting solution and then irradiating with a defined dose of electron beam radiation, for example with accelerating voltage from 230 to 270 kV and dose from 130 to 170 kGy, whereas the first batch is immersed in the grafting solution containing at least one hydrophilic monomer, but the second batch is immersed in the grafting solution containing at least one hydrophobic monomer; step g) longitudinal slitting of the rubber band (9), that follows immediately step f) or is carried out between steps e) and f); step h) cutting the rubber band (9) transversally into shorter pieces; step i) the cut pieces of the two batches are mixed in the predefined weight-to-weight ratio.
  5. The method according to claim 4, characterized in that the hydrophilic grafting monomer is chosen from the group of monomers: acrylates, methacrylates, vinyl monomers and nitrile monomers, or combination of any of them.
  6. The method according to claim 4 or 5, characterized in that the hydrophobic grafting monomer is chosen from the group of monomers: perfluorooctyl acrylate, perfluoropolyether, trichlorosilane, trimethoxysilyl-functionalized acrylates/methacrylates, silane modified acrylates/methacrylates, butyl acrylate, stearyl acrylate or combination of any of them.
  7. The method according to any one of claims 4 to 6, characterized in that the grafting solution further contains a cool grade pigment and/or transparent infrared reflecting pigments and/or UV stabilizer and/or antioxidant or combination of any of them.
  8. The method according to any one of claims 4 to 7, characterized in that in step b) the devulcanized rubber material in an amount of 100 parts by weight is mixed with vulcanizing additive in an amount of from 0.1 to 3 parts by weight of rubber, for example sulphur, and with vulcanizing activator/s in total amount of from 0.1 to 5 parts by weight of rubber, for example zinc oxide and stearic acid in combination.
  9. The method according to claim 8, characterized in that an accelerator is further added in an amount of from 0.1 to 3 parts by weight of rubber to form rubber compound in step b), for example N-cyclohexyl-2-benzothiazolesulfenamide.
  10. The method according to claim 8 or 9, characterized in that a plasticizer is further added in an amount of from 1 to 30 parts by weight of rubber to form the rubber compound in step b), for example Treated Distillate Aromatic Extract.
  11. The method according to any one of claims 8 to 10, characterized in that a fire-resistant additive is further added in an amount of from 1 to 60 parts by weight of rubber to form rubber compound in step b), for example ammonium phosphate.
  12. The method according to any one of claims 8 to 11, characterized in that an antioxidant is further added in an amount of from 0.1 to 3 parts by weight to form a rubber compound in step b), for example N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine.
  13. The method according to claim to any one of claims 4 to 12, characterized in that the devulcanized rubber material contains styrene-butadiene rubber and natural rubber, for example said material is obtained from tire recycling waste material.
  14. A processing line for carrying out steps c) to h) of the method according to any one of claims 4 to 13 continuously in a roll-to-roll manner, characterized in that it contains the feed section (7) for feeding a homogenous rubber compound into the extruder, a number of motor-driven rollers (8) for moving the rubber band (9) through units, and units in the following sequence of the movement of the rubber band (9): extruder, cooling tunnel (10), station with pre-irradiation zone (11), dipping tray (12), station with main radiation zone (13), slitting means (14) and cutting means (15).
  15. The processing line according to claim 14 wherein the slitting and/or cutting means (14, 15) are laser beam machine/s or a mechanical machine/s, preferably a CO 2 laser machines.
  16. A production unit containing two processing lines according to any one of claims 14 to 15, wherein the dipping tray (12) of the first processing line contains a hydrophobic grafting solution, the dipping tray (12) of the second processing line contains a hydrophilic grafting solution, there is a silo (16) for hydrophobic cut pieces at the end of the first processing line, and a silo (17) for hydrophilic cut pieces (1) at the end of the second processing line, and a mixer common to both processing lines, where both silos (16, 17) are arranged to feed the cut pieces to the mixer.
  17. A production unit that contains the processing line according to any one of claims 14 to 15, at least one silo, preferably two silos (16, 17), at the end of processing line to collect cut pieces produced in two consecutive production cycles and a common mixer arranged to be fed by cut pieces from both production cycles from said silo or silos (16, 17), wherein the dipping tray (12) interchangeably contains hydrophilic grafting solution for performing the first production cycle, and hydrophobic grafting solution for performing the second production cycle.

Description

RUBBER MULCH The present invention relates to rubber mulch, its production method, production unit and processing line to produce said rubber mulch for application by spreading in the landscape for passive collection of atmospheric moisture and soil wetting by spontaneous flow of water into the ground. Colored rubber mulches derived from recycled tires are commonly used in landscape applications due to their durability, weather resistance, low mobility, and ability to retain water in the substrate ground, preventing evaporation under sunlight. They also exhibit good noise dampening and acoustic properties when spread on landscapes. Despite these benefits, the widespread use of recycled tire rubber mulches is limited due to several drawbacks. Although conventional rubber mulches are known for their ability to retain water and prevent evaporation, they still lack the ability to increase soil moisture. In addition, the color coating methods used on rubber mulch result in poor color durability, and recycled tire rubber mulch can act as fuel in case of a fire, posing a fire risk. Additionally, unpleasant odours can be emitted during sunlight. The problem how to increase the soil moisture is solved by a rubber mulch for application as a ground cover according to the invention, where said rubber mulch contains pieces of hydrophobic modified rubber mixed with pieces of hydrophilic modified rubber in a weight-to-weight ratio from 10:90 to 90:10, preferably 40: 60 to 60:40. Compared to conventional mulches known from the prior art, which are only able to retain water and prevent evaporation, the pieces of hydrophobically and hydrophilically modified rubber in the much of the invention have the additional ability to passively collect a quantum of moisture from the atmosphere on the principle of dew formation disclosed in more detail below. Therefore, said hydrophobically and hydrophilically modified rubber pieces increase the amount of accumulated water and thereby increase the moisture content of the mulch. In addition, the hydrophobic particles repel the collected water and drain it extensively into the soil. In this way, the moisture content in the soil is increased synergistically by the presence of both, hydrophobically and hydrophilic modified rubber pieces. Extensive evaporation into the atmosphere is also prevented. It is advantageous if said rubber pieces have at least two different lengths ranging from 30 to 150 mm, more preferably from 50 to 100 mm, and width preferably in range from 5 to 50 mm, more preferably from 15 to 25 mm. Preferably, the rubber pieces are formed into shapes and dimensions to resemble conventional mulches from natural materials. The surface area of the rubber pieces can be advantageously increased, for example by corrugation resulting in the cutting edges being serrated and sinuate or by grooving, notching, indentation or by other methods of increasing the surface area. Another aspect of the invention is a method of producing above-mentioned rubber mulch in its basic form or with various optional improvements that eliminate other disadvantages of the conventional prior art, e. g fire resistance, durability and color fastness, unpleasant odours, etc. In this method in step a) a devulcanized rubber material is obtained as the primary component, preferably in the form of granules or powder or sheets; and then at least two batches of rubber material are processed by consecutive steps from b) to h), which differ in step f) for each of the batches in the type of grafting solution, therefore at least step f), but advantageously all of steps b) to h) are performed separately for each batch, and finally said batches are mixed together in step i); whereas the steps from b) to i) are as follows: step b) forming a homogeneous rubber compound as a feed material for an extruder by mixing said devulcanized rubber material with at least a vulcanizing agent and a vulcanization activator; step c) creating a rubber band with a bottom surface and a top surface by extruding the homogenous rubber compound from step b) at a temperature from 100°C to 180°C and extruding pressure from 1 to 100 MPa in an extruder through its die of defined shape and dimensions; step d) cooling down of the rubber band; step e) creating a reactive surface on the rubber band by pre-irradiating the bottom surface and the top surface of the rubber band with a defined dose of radiation, for example with an electron beam at an accelerator voltage of 130 to 170 kV and a dose value of of 25 to 40 kGy; step f) grafting by immersing each electron beam pre-irradiated batch in a grafting monomer and then irradiating with a defined dose of electron beam radiation, for example with accelerating voltage from 230 to 270 kV and dose from 130 to 170 kGy, whereas the first batch is immersed in the grafting solution containing at least one hydrophilic monomer, but the second batch is immersed in the grafting solution containing at least one hydrop