Method for recovering silicate from a polymer composition containing silica

Abstract

A method for recovering a silicate from a polymer composition containing silica, which is characterized by mild reaction conditions, is provided. The silicate can be recovered without decomposing or depolymerizing the polymer composition.

Description

Technical Field

[0001] The present disclosure relates to a method for recovering silicate from a polymer composition containing silica.

Background Art

[0002] The following discussion of the prior art is provided to place the present disclosure in its appropriate technical context and to enable a more complete understanding of its advantages. However, it should be understood that no discussion of the prior art throughout this specification should be construed as an admission that such prior art is widely known or forms part of the common general knowledge in the art.

[0003] The use of precipitated silica as a reinforcing filler in polymer compositions is known. Specifically, the use of precipitated silica as a reinforcing filler in elastomer compositions is known. Such use is very demanding: the filler must be easily and efficiently incorporated and dispersed in the elastomer composition and must typically chemically bond with a coupling reagent on one hand to the elastomer and on the other hand to the silica to provide high and homogeneous reinforcement of the elastomer composition. Generally, precipitated silica is used to improve the mechanical properties, processability, and wear performance of elastomer compositions.

[0004] Polymer compositions containing silica, such as automobile tires, are typical examples of products obtained from non-renewable petroleum resources. Currently, pyrolysis is considered a beneficial industrial process that adds value to waste rubber compounds by recovering materials and energy. However, high temperatures are required. Generally, such methods of utilizing non-renewable petroleum resources are inefficient. If waste polymer compositions are not properly disposed of and the residues cannot be easily reused, there is a risk of polluting the local environment. Silica is hardly recycled in such processes and is often regarded as a "toxin". To enhance the reuse value of other residues, it is considered beneficial to remove silica before or after further treatment.

[0005] Therefore, there is still a need to develop methods for recovering silicates from polymer compositions containing silica, particularly from waste tires considered to be off-specification (in terms of performance, size, etc.), and further from discarded process rubber compounds.

Summary of the Invention

Means for Solving the Problems

[0006] Accordingly, an object of the present disclosure is to provide a method for recovering silicate from a polymer composition containing silica, which is characterized by mild reaction conditions.

[0007] Accordingly, the present disclosure relates to a method for recovering silicate from a polymer composition containing silica, comprising: (i) contacting the polymer composition containing silica with a base in the presence of a solvent; (ii) reacting the base with the silica to form a silicate, thereby obtaining a polymer composition in which at least a part of the silica is lost and a solution containing the silicate; and (iii) separating the solution obtained in step (ii) from the polymer composition obtained in step (ii). The present disclosure relates to a method comprising the above steps.

[0008] Other subjects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description and examples.

Brief Description of the Drawings

[0009]

Figure 1

Modes for Carrying Out the Invention

[0010] Definitions In this specification, the terms "silica" and "precipitated silica" are used as synonyms.

[0011] Throughout this specification, including the claims, the term "comprising one" should be understood to have the same meaning as the term "comprising at least one" unless otherwise specified, and "between" should be understood to include both ends.

[0012] Regarding the organic groups used in this specification, the term "(C n ~C m )" (wherein both n and m are integers) indicates that the group may contain from n carbon atoms to m carbon atoms per one group.

[0013] The articles "a", "an" and "the" are used to refer to one or more than one (i.e., at least one) of the grammatical objects of the article.

[0014] The term "and / or" includes not only the meanings of "and" and "or", but also all other possible combinations of the elements related to this term.

[0015] In the continuation of the description, unless otherwise specified, it is specified that the end values are included in the given value range.

[0016] Ratios, concentrations, amounts, and other numerical data may be presented in a range format in this specification. Such range formats are used merely for convenience and brevity and are to be construed flexibly as encompassing not only the numerical values explicitly recited as the upper and lower limits of the range but also all the individual numerical values or sub-ranges subsumed within that range as if each numerical value and sub-range were explicitly recited.

[0017] Detailed Description of the Invention The present disclosure is a method for recovering a silicate from a polymer composition containing silica, comprising: (i) contacting a polymer composition containing silica with a base in the presence of a solvent; (ii) reacting the base with the silica to form a silicate, thereby obtaining a polymer composition in which at least a part of the silica is lost and a solution containing the silicate; and (iii) separating the solution obtained in step (ii) from the polymer composition obtained in step (ii). A method including the above steps is provided.

[0018] As used herein, the term "polymer composition" refers to a composition containing at least one polymer. The phrase "at least one kind" when referring to the polymer in the composition is used herein to indicate that one or more polymers of each type can be present in the composition.

[0019] As used herein, the expression "copolymer" refers to a polymer containing repeating units derived from at least two monomer units of different properties.

[0020] The at least one polymer can be selected from among thermosetting polymers and thermoplastic polymers, with the latter being preferred.

[0021] Non-limiting examples of suitable thermoplastic polymers include styrenic polymers such as polystyrene, (meth)acrylate / styrene copolymers, acrylonitrile / styrene copolymers, styrene / maleic anhydride copolymers, and ABS; acrylic polymers such as polymethyl methacrylate; polycarbonates; polyamides; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyphenylene ethers; polysulfones; polyaryl ether ketones; polyphenylene sulfides; thermoplastic polyurethanes; polyethylene; polypropylene; polybutene; poly-4-methylpentene; polyolefins such as ethylene / propylene copolymers and ethylene / α-olefin copolymers; copolymers of α-olefins with various monomers, such as ethylene / vinyl acetate copolymers, ethylene / (meth)acrylate copolymers, ethylene / maleic anhydride copolymers, ethylene / acrylic acid copolymers; aliphatic polyesters such as polylactic acid, polycaprolactone, and aliphatic glycol / aliphatic dicarboxylic acid copolymers.

[0022] Silica can advantageously be present in the elastomeric composition as a reinforcing filler. Non-limiting examples of suitable elastomers are diene elastomers. For example, elastomers derived from at least one unsaturated aliphatic or aromatic monomer such as ethylene, propylene, butadiene, isoprene, styrene, acrylonitrile, isobutylene or vinyl acetate, polybutyl acrylate or mixtures thereof can be used. Also included are functionalized elastomers (e.g., by functional groups capable of reacting with the surface of silica) and halogenated polymers, which are elastomers functionalized by chemical groups located along the polymer chain and / or at one or more of its ends. Examples include polyamides, ethylene homo- and copolymers, and propylene homo- and copolymers. Other suitable elastomers include those containing chloro- or bromo-butyl monomers (such as bromo-butylene).

[0023] Among diene elastomers, for example, polybutadiene (BR), polyisoprene (IR), butadiene copolymers, isoprene copolymers, or mixtures thereof, in particular styrene / butadiene copolymers (SBR, in particular ESBR (emulsion) or sSBR (solution)), isoprene / butadiene copolymers (BIR), isoprene / styrene copolymers (SIR), isoprene / butadiene / styrene copolymers (SBIR), ethylene / propylene / diene terpolymers (EPDM), and furthermore related functionalized polymers (for example, those having pendant polar groups, or reactive or polar groups at the chain ends that can interact with or react with silica) can be mentioned.

[0024] Natural rubber (NR) and epoxidized natural rubber (ENR) can also be mentioned.

[0025] The polymer composition can be vulcanized with sulfur or, specifically, crosslinked with peroxides or other crosslinking systems (for example, diamines or phenolic resins).

[0026] The type of silica according to the present disclosure is not particularly limited. This may be a conventional or highly dispersible silica such as Zeosil® Premium SW, Zeosil® Premium 200MP, Zeosil® 1165MP, Zeosil® 1115MP, or Zeosil® 1085 GR (commercially available from Solvay).

[0027] The surface area of the mesoporous silica (using CTAB as a template) according to the present disclosure may be 40 to 500 m 2 / g.

[0028] The BET surface area of the silica according to the present disclosure may be 40 to 500 m 2 / g.

[0029] The weight ratio of silica in the polymer composition can vary within a fairly wide range. This usually accounts for 0.01% to 40%, particularly 10% to 40%, and particularly 20% to 40% relative to the amount of the polymer.

[0030] In the case of an elastomer composition, % may be referred to as phr or Per Hundred Rubber. Preferably, the silica in the polymer composition may be 5 to 200 phr, more preferably 5 to 150 phr.

[0031] The applicant has found that the higher the silica content in the polymer composition, the higher the recovery efficiency of the silicate.

[0032] In some embodiments, the polymer composition may further contain other inorganic reinforcing fillers such as nanoclay and alumina, or organic reinforcing fillers such as carbon black, carbon black nanotubes, graphene, starch, and cellulose.

[0033] In that case, the silica according to the present disclosure preferably constitutes at least 5% by weight, preferably at least 30% by weight, more preferably 60% by weight, and actually at least 80% by weight of the total amount of the reinforcing filler.

[0034] In a preferred embodiment, the polymer composition contains silica and carbon black. The weight ratio of silica and carbon black can be 1% to 50% relative to the amount of the polymer.

[0035] Advantageously, the polymer composition containing silica, particularly a tire, particularly a polymer composition containing silica recovered from waste tires, can be supplied in powder form. Those skilled in the art can determine a measurement method for obtaining the average particle size and / or particle size distribution, such as a scanning electron microscope (SEM), a particle size distribution analyzer (PSD), or a vernier caliper, according to processing processes such as cryogenic grinding, shredding process, and grinding process.

[0036] For SEM analysis, a ZEISS EVO-18 with a tungsten filament at a voltage of 20 kV equipped with a backscattered electron detector (BSD) or a secondary electron detector was used. The magnification can reach up to 50K - 100K. The SEM was used to detect particle sizes in the range of 200 nm to 1000 μm. The particles were deposited on a layer of graphite tape, coated with Pt for 40 seconds, and measured with the SEM. The obtained results were analyzed using SmartSEM software. Approximately 10 photos were taken for each sample, and a total of 100 particles were analyzed to obtain the particle size distribution described above. From this particle size distribution, the average particle size was obtained. The software used to measure the particle size was ImageJ, by which the particles were approximated to have an irregular shape and the longest distance was measured. After setting the scale, the longest diameter of each particle was measured manually, and the total number of measured particles was set to 100. All the particles were measured three times to obtain the average size.

[0037] For the particle size distribution analyzer (PSD), a Malvern Mastersizer 3000 with a range lens of 300 RFmm was used. The PSD was used to detect particle sizes in the range of 10 nm to 3.5 mm. The particles were dissolved in ethanol and the mixture was stirred for 10 minutes. The dispersed sample passed through the measurement area of the optical bench where the laser light irradiates the particles. Subsequently, a series of detectors accurately measure the intensity of light for both red and blue wavelengths scattered by the particles in the sample over a wide range of angles. To obtain particle size distributions such as D10, D50, and D90, at least three parallel samples were prepared and measured. The particle size distributions D10, D50, and D90 represent that 10%, 50%, or 90% of the particles in the powder are smaller than the size in this range.

[0038] For caliper analysis, calipers were used to measure particle sizes exceeding 1000 μm. The longest diameter of each particle was measured manually. Approximately 100 particles were measured to obtain the average value of the particle size distribution.

[0039] The method for preparing the powder is not particularly limited. For example, one skilled in the art can prepare the powder using mechanical forces such as crushing (micronization, rolling, and coarse crushing), grinding (by balls and rods), and further cutting. In a preferred embodiment, the powder can be prepared by cryogenic grinding.

[0040] Polymer compositions containing silica, especially tire, especially polymer compositions containing silica recovered from waste tires, may require pretreatment. One skilled in the art will understand that different parts of waste tires may require different pretreatments.

[0041] For example, the tread of a tire, which is a part rich in silica, can be removed from the tire by a machine equipped with a blade system and then can be cut and ground.

[0042] As another example, when parts other than the tread of a waste tire or the whole waste tire are pretreated, one skilled in the art can first powderize the parts other than the tread or the whole tire and then remove the metal parts and fiber parts in the tire. For example, the pretreatment may be the method disclosed in U.S. Patent Application Publication No. 2017 / 0043351, which includes the steps of pre-treatment crushing of the feed material, cryogenic freezing, and grinding, and heating of the micronized material, removal of ferrous metals and fibers, accumulation, sieving, and storage. The pretreatment can also be a method including the steps of cutting treatment, metal removal, and fiber removal.

[0043] In this specification, the term "base" is used to refer to one or more bases. Any base can be used in the method as long as it can react with silica to form a silicate. Non-limiting examples of suitable bases are inorganic bases such as alkali metal hydroxides, alkaline earth metal hydroxides, and ammonia. Preferably, the base can be sodium hydroxide or potassium hydroxide.

[0044] The solvent according to the present disclosure is not particularly limited. Advantageously, the solvent is stable under alkaline conditions. The solvent may be water, an organic solvent, or a mixture thereof. The organic solvent preferably has a total Hansen solubility parameter of less than 33 MPa 1 / 2 , preferably 15 to 29 MPa 1 / 2 , more preferably 20 to 25 MPa 1 / 2 .

[0045] Preferably, the solvent can contain water. In this case, when the base is an inorganic base, advantageously, it can be dissolved in water to form an aqueous solution before contacting the polymer composition. The concentration of the base in the aqueous solution can advantageously be 4 wt% to 50 wt%, preferably 8 wt% to 40 wt% based on the total weight of the aqueous solution.

[0046] In some embodiments, the solvent can consist of water.

[0047] In some embodiments, the solvent may be a mixture of water and an organic solvent. The organic solvent can be selected from the group consisting of toluene, xylene, acetone, DMSO, and alcohol. Preferably, the organic solvent can be selected from the group consisting of DMSO, toluene, acetone, 1-propanol, 2-propanol, 2-butanol, and tert-butyl alcohol, more preferably, it can be selected from the group consisting of toluene, acetone, 1-propanol, 2-propanol, 2-butanol, and tert-butyl alcohol, and most preferably, it can be selected from the group consisting of 1-propanol, 2-propanol, and 2-butanol.

[0048] In certain embodiments, when the solvent is a mixture of water and an organic solvent, the volume ratio of water to the organic solvent can be 0.1:1 to 10:1, preferably 0.2:1 to 3:1.

[0049] The molar ratio of the base to the silica can advantageously be 40:1 to 1:1, preferably 20:1 to 2:1, more preferably 5:1 to 2:1.

[0050] The reaction temperature of step (ii) can be 25 to 180°C, preferably 40 to 120°C, more preferably 70 to 100°C.

[0051] The reaction time of step (ii) can be 2 to 48 hours, preferably 3 to 24 hours.

[0052] The reactor can preferably be made of a material resistant to the above-mentioned organic solvent and base, such as Teflon or Hastelloy.

[0053] The method for separating the solution and the polymer composition in step (iii) is not particularly limited. The method can be centrifugation and / or decantation according to the particle size.

[0054] Advantageously, by using the method according to the present disclosure, it is possible to recover the silicate without decomposing or depolymerizing the polymer composition.

[0055] Advantageously, at least 50% by weight, preferably at least 60% by weight, more preferably at least 80% by weight of the silica in the polymer composition is recovered, which is calculated based on the silicon content in the solution obtained in step (iii).

[0056] The silicate recovered by the method according to the present disclosure can be advantageously used in the production of silica, particularly precipitated silica.

[0057] Precipitated silica can be produced from silicates recovered by processes well known to those skilled in the art. Such processes typically involve reacting the recovered silicate with an aqueous acid solution to obtain a slurry containing precipitated silica particles. Such processes typically also involve filtering the slurry and, optionally, washing it to obtain a suspension of silica particles ("filter cake"), and drying the filter cake to obtain precipitated silica in powder form. A suitable process among several processes is described and exemplified in U.S. Patent No. 11,241,370, the entire content of which is incorporated herein by reference for all purposes.

[0058] The term "acid" is used herein to refer to one or more acids that can be added during the course of the method of the present invention. Any acid can be used in the method. Generally, mineral acids such as sulfuric acid, nitric acid, phosphoric acid or hydrochloric acid, or organic acids such as carboxylic acids, for example acetic acid, formic acid, or carbonic acid are used. Good results are obtained with sulfuric acid.

[0059] Those skilled in the art will understand that adding an acid will lower the pH of the solution. Preferably, the pH can be lowered to a value of less than 6, more preferably less than 5.

[0060] Advantageously, the method according to the present disclosure can be used for the recycling of waste tires, which contributes to the production of silicates or precipitated silica.

[0061] The following examples are included to illustrate embodiments of the present disclosure. Needless to say, the present disclosure is not limited to the described examples.

Examples

[0062] Materials · A simple green tire tread compounding sheet containing 32% by weight of SiO2 (Solvay); · Sodium hydroxide (CAS: 1310-73-2, >96%, Sinopharm); · Dimethyl sulfoxide (DMSO) (CAS: 67-68-5, 99%, J&K); · tert-Butyl alcohol (CAS: 75-65-0, 99.5%, J&K); · Ethylene glycol (CAS: 107-21-1, 99.5%, J&K); · Acetone (CAS: 67-64-1, ≧99.5%, AR, Sinopharm); · Toluene (CAS: 108-88-3, ≧99.5%, AR, Sinopharm); · 1-Propanol (CAS: 71-23-8, ≧96%, Sinopharm); · 2-Propanol (CAS: 67-63-0, ≧96%, Sinopharm); · 2-Butanol (CAS: 78-92-2, CP, Sinopharm); · Ethanol (CAS: 64-17-5, ≧95%, Sinopharm).

[0063] Preparation of green tire powder The simplified green tire tread compound sheet prepared by Solvay was shredded and cut into powder. The particle size distribution of the powder was determined by a Malvern Mastersizer 3000, which is a particle size distribution analyzer (PSD). The tire powder was dispersed in ethanol in the sample unit while stirring and left as it was for about 10 minutes to uniformly disperse the sample. The test was repeated 6 times to obtain consistent results shown in Figure 1. According to the PSD, 90% of the particles had a particle size of less than 338 μm, 50% had a particle size of less than 190 μm, and 10% had a particle size of less than 94.5 μm.

[0064] Example 1 The tire was treated with an aqueous NaOH solution without using an organic solvent.

[0065] In a typical procedure, green tire powder (1.5 g) and an aqueous NaOH solution (33 wt%, 15 ml) were sequentially placed into a Teflon reactor equipped with a Teflon condenser. The mixture was heated at 85 °C and stirred for 22 hours. After the reaction, the mixture was transferred to a centrifuge tube. The reactor was washed with a mixture of EtOH and H2O (20 mL) to completely remove the solvent and residual tire from the reactor and transfer them to the centrifuge tube. The mixture was centrifuged at 10,000 rpm for 5 minutes to separate the tire from the liquid. The separated liquid was stored in a container, and then a fresh mixture of EtOH and H2O was added to the centrifuge tube to remove residual NaOH from the tire. This procedure was repeated several times until the pH of the separated liquid reached 7. Finally, the wet tire was vacuum dried at 100 °C. All the separated liquid in the container was concentrated to 50 ml by distilling it off at 40 °C and 60 mbar. The silicon content in the liquid and the amount of silicon in the remaining tire were quantified by ICP. From the following equation, the amount of SiO2 extracted in the liquid, the amount of SiO2 remaining in the tire, and the SiO2 mass balance before and after the reaction were calculated. [Number]

[0066] Example 2 The tire was treated with an aqueous NaOH solution and 2-propanol.

[0067] In a typical procedure, green tire powder (1.5 g), aqueous NaOH solution (33 wt%, 15 ml), and 2-propanol (10 ml) were sequentially placed into a Teflon reactor equipped with a Teflon condenser. The mixture was heated at 82 °C and stirred for 22 h. After the reaction, the mixture was transferred to a centrifuge tube. The reactor was washed with a mixture of EtOH and H2O (20 mL) to completely remove the solvent and residual tire from the reactor and transfer them to the centrifuge tube. The mixture was centrifuged at 10,000 rpm for 5 min to separate the tire from the liquid. The separated liquid was stored in a container, and then a fresh mixture of EtOH and H2O was added to the centrifuge tube to remove the residual NaOH from the tire. This procedure was repeated several times until the pH of the separated liquid reached 7. Finally, the wet tire was vacuum dried at 100 °C. All the separated liquid in the container was concentrated to 50 ml by distilling it off at 40 °C and 60 mbar. The silicon content in the liquid and the amount of silicon in the remaining tire were quantified by ICP.

[0068] Example 3 The tire was treated with aqueous NaOH solution and 1-propanol.

[0069] The reaction protocol was the same as in Example 2 except that 10 ml of 1-propanol was added.

[0070] Example 4 The tire was treated with aqueous NaOH solution and 2-butanol.

[0071] The reaction protocol was the same as in Example 2 except that 10 ml of 2-butanol was added.

[0072] Example 5 The tire was treated with aqueous NaOH solution and tert-butyl alcohol.

[0073] The reaction protocol was the same as in Example 2 except that 10 ml of tert-butyl alcohol was added.

[0074] Example 6 The tire was treated with aqueous NaOH solution and toluene.

[0075] The reaction protocol is the same as that of Example 2 except that 10 ml of toluene was added and the reaction temperature was 105°C.

[0076] Example 7 The tire was treated with an aqueous NaOH solution and acetone.

[0077] The reaction protocol is the same as that of Example 2 except that 10 ml of acetone was added and the reaction temperature was 105°C.

[0078] Example 8 The tire was treated with an aqueous NaOH solution and dimethyl sulfoxide (DMSO).

[0079] The reaction protocol is the same as that of Example 2 except that 10 ml of DMSO was added and the reaction temperature was 105°C.

[0080] Example 9 The tire was treated with an aqueous NaOH solution and ethylene glycol.

[0081] The reaction protocol is the same as that of Example 2 except that 10 ml of ethylene glycol was added.

[0082]

Table 1

[0083] Table 1 shows that various solvents combined with the NaOH solution can be used for the extraction of SiO2 from the tire. Among these, 2-propanol is the most effective solvent.

[0084] Example 10 The tire was treated with an aqueous NaOH solution and DMSO.

[0085] The reaction protocol is the same as that of Example 8 except that 15 ml of an aqueous NaOH solution (concentration 18% by weight) was added.

[0086] Example 11 The tire was treated with an aqueous NaOH solution and tert-butyl alcohol.

[0087] The reaction protocol was the same as in Example 5, except that 15 ml of an aqueous NaOH solution (concentration 18% by weight) was added.

[0088] [Table 2]

Claims

1. A method for recovering a silicate from a polymer composition containing silica, comprising: (i) contacting the polymer composition containing silica with a base in the presence of a solvent; (ii) reacting the base with the silica to form a silicate, thereby obtaining a polymer composition in which at least a part of the silica is lost and a solution containing the silicate; and (iii) separating the solution obtained in step (ii) from the polymer composition obtained in step (ii). A method comprising the above steps.

2. The method according to claim 1, wherein the solvent is water, an organic solvent, or a mixture thereof.

3. The method according to claim 1 or 2, wherein the solvent is a mixture of water and an organic solvent.

4. The organic solvent has a Hansen solubility parameter of less than 33 MPa １／２ , preferably 15 to 29 MPa １／２ , more preferably 20 to 25 MPa １／２ , and the method according to any one of claims 1 to 3.

5. The method according to any one of claims 1 to 4, wherein the organic solvent is selected from the group consisting of toluene, xylene, acetone, DMSO, and alcohol.

6. The method according to any one of claims 1 to 5, wherein the organic solvent is selected from the group consisting of DMSO, toluene, acetone, 1-propanol, 2-propanol, 2-butanol, and tert-butyl alcohol.

7. The method according to any one of claims 1 to 6, wherein the organic solvent is selected from the group consisting of toluene, acetone, 1-propanol, 2-propanol, 2-butanol, and tert-butyl alcohol.

8. The method according to any one of claims 1 to 7, wherein the organic solvent is selected from the group consisting of 1-propanol, 2-propanol, and 2-butanol.

9. The method according to any one of claims 1 to 8, wherein the molar ratio of the base to silica is from 40:1 to 1:1, preferably from 20:1 to 2:1, more preferably from 5:1 to 2:

1.

10. The method according to any one of claims 1 to 9, wherein the base reacts with silica at a temperature of 25 to 180 °C, preferably 40 to 120 °C, more preferably 70 to 100 °C.

11. The method according to any one of claims 1 to 10, wherein the weight ratio of silica in the polymer composition is 0.1% to 40%, particularly 10% to 40%, particularly 20% to 40% based on the amount of the polymer.

12. The method according to any one of claims 1 to 11, wherein the polymer composition containing silica is in powder form.

13. The method according to any one of claims 1 to 12, further comprising recovering the polymer composition containing silica from a tire.

14. A method for producing precipitated silica, comprising: - recovering a silicate from a polymer composition containing silica by the method according to any one of claims 1 to 12, and - producing precipitated silica using the recovered silicate. A method comprising the above.

15. The method according to claim 14, further comprising recovering the polymer composition containing silica from a tire.

16. Use of the method according to claim 13 or 15 for recycling waste tires.

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