Technical Field of the Invention

The present invention related to recycled nylon 6.6 pellet production from tire grade nylon 6.6 yam scraps. Said recycled nylon 6.6 pellet is used in tire grade nylon 6.6 yarn production in different ratio with virgin nylon 6.6 pellet. Aim of this study is to get the comparable physical, thermal, mechanical properties and production process with recycled nylon 6.6. tire grade yam with respect to virgin one. The study also serves the global sustainability issues that will deeply explain in below.

Prior Art

Nylon is a polymer, composed of repetitive units of diamines and dicarboxylic acids that contains different numbers of carbon atoms. Polymerization reaction takes place in a batch or continuous process in accompany with pressure, vacuum and heat. Nylon 6.6 thermoplastic polymer is made from petrochemical monomers, combined to form a long chain through a condensation polymerisation reaction.

Petroleum based polymers have been used since a long time due to its handiness, durability, flexibility, and less reactivity towards the water and other chemical. In the recent year, with the rise of global environment and sustainability issues, mankind begin to realize that word have limited petrochemical sources. This will endanger the balance between nature of the environment and development of science. Therefore, how to respect both of the environment and human development is became a challenging issue for the recent studies.

Nylon is not biodegradable, and will persist in the environment indefinitely. The two of the largest sources of microplastic pollution in the ocean are nylon fishing nets and synthetic textile fibers. This means that the impact of nylon on the aquatic environment is significant. On the other hand, the persistent nature of nylon means that it is infinitely recyclable and we could cease new nylon production now and still meet our desire for nylon if we recycled all of the nylon material currently in existence. Thus, it is need to increase the accessibility of nylon recycling schemes to the average consumer.

Brief Description and Objectives of the Invention

The present invention consists of two main processes and products as indicated below. i. Recycled nylon 6.6. pellet production from tire grade oiled and non-oiled nylon 6.6 drawn and undrawn yam scraps that are occurred standard tire grade yam production. ii. Tire grade yarn production with the mixture of virgin and recycled nylon 6.6 pellets in a different recycled pellet ratio with a comparable process and product properties.

Pellet mixture that is consist of certain proportion of virgin and recycled nylon 6.6 pellets are go through the solid state polymerization process in a certain conditioning temperature to get the desired relative viscosity level for the spinning process. Virgin to recycle pellet level of 10:90 to 90:10, preferably production performed in range of 80:20 to 50:50 to get the comparable yield, process performance, productivity, sustainability of the production and product and also yarn properties. Both of the flake type has maximum 0,5 % moisture level.

Addition to that, chopped nylon 6.6 yam scraps finish oil level is between 0, 7-1,0 %. Before the recycled nylon 6.6 pellet production, there is no washing unit for scraps to get rid of the oil. Finish oil is removed from the scrap polymer in the vacuum zone of the extruder during the recycled nylon 6.6 pellet production steps that was detailed explained in Figure 2. At the end of the production, nylon 6.6 recycled pellet has between 0,01 to 0,05 % finish oil level.

Definitions of the Figures Describing the Invention The present disclosure can be more understood by reading the following detailed description of the drawings as follows;

Figure 1: Standard yam bobbins (1.8)( tire grade nylon 6.6 yarn bobbins ) production steps consist of virgin nylon 6.6 pellets (virgin nylon 6.6 pellets flake) (1.1) fed to silos, first nylon 6.6 pellets purged (1.2) and then they have solid state polymerization process (1.3), polymerized nylon 6.6 pellets converted to molten nylon 6.6 polymer (1.4), molten nylon 6.6 polymer go through a die to get the round filament shape (1.5), nylon 6.6 polymer filament cooled(1.6), nylon 6.6 filament have some process steps to get the desire end properties(1.7), at the end tire grade nylon 6.6 yarn bobbins (1.8) were produced.

Figure 2: The method for recycling nylon 6.6 pellets includes the steps of collecting oiled and non-oiled nylon 6.6 drawn and undrawn yarn scraps during yarn production (2.1); chopping nylon 6.6 yarn scraps into short strands (2.2) ; transporting the chopped nylon 6.6 yarn scraps to the compressing unit (2.3); feeding the compressed nylon 6.6 scraps into the extruder(2.4); melting of nylon 6.6 scraps(2.5); vacuuming of oil from molten polymer (2.6) ; to form nylon 6.6 strands (2.7); cooling the nylon 6.6 strands in the water bath (2.8); drying nylon 6.6 strands coming out of the water bath (2.9); pelletizing of nylon 6.6 strands (2.10); collecting recycled nylon 6.6 pellets (2.11) and packaging of recycled nylon 6.6 pellets (2.12) .

Figure 3: This figure is very similar to Figure 1. Only difference is; at the beginning of the process, virgin (3.1) and recycled (3.2) flakes are mixed homogeneous with a blending system in a certain proportion.

Tire grade yarn: Nylon 6.6 yarn that have minimum 8,0 gpd (grams per denier) tenacity and 100 to 5000 dtex density level.

4 % SASE: Stress at 4 % elongation (gpd)

Tenacity: strength of yarn (gram) / density of yarn (denier) (gpd)

Virgin nylon 6.6 pellet: Raw nylon 6.6 pellet

Recycled nylon 6.6 pellet: nylon 6.6 pellet that is form from scrap material Tire grade nylon 6.6 yarn: nylon 6.6 yarn used in cord in tires

Oiled and non-oiled nylon 6.6 drawn and undrawn yarn scraps: yarn scraps that are processed and unprocessed

Nylon 6.6 strands: molten polymer after the extruder (like a spaghetti)

Detailed Description of the Invention

The invention relates to a tire grade nylon 6,6 mono- and/or multi filament yam comprising at least 10 % recycled nylon 6,6, preferably 20% recycled nylon 6,6 wherein the said nylon 6,6 mono or multi filament yam has at least 8,0 gpd tenacity according to ASTM-D 885.

ASTM-D 885 is a standard test methods for tire cords, tire cord fabrics, and industrial filament yams made from man-made organic-base fibers.

The tire grade nylon 6,6 mono- and/or multi filament yarn has at least 1,25 gpd 4 % SASE according to ASTM-D 885.

A manufacturing method of a tire grade nylon 6,6 mono- and/or multi filament yam comprises the steps of: a) Recycled nylon 6.6 pellet production,

• Cutting of tire grade oiled and/or non-oiled drawn and/or undrawn nylon 6.6 fiber scraps including mono- and/or multi- filament yarn into 3 cm to 5 cm to get nylon 6.6 chopped fibers,

• Feeding to extruder that has minimum 250°C and maximum 290°C in 6 zones to get the molten nylon 6.6 polymer from the scrap yarns,

• Cooling of strands,

• Cutting in a size between 300 to 500 pellet in 10 gram which is shaped as a pellet form, wherein recycled nylon 6.6 pellet that has maximum 0,05 % finish oil in it, b) Virgin nylon 6.6 pellet production, c) Mixture of virgin and recycled nylon 6.6 pellets in minimum 20 % recycle pellet ratio to produce tire grade recycled nylon 6.6 yam.

At the beginning of the process, tire grade oiled and/or non-oiled drawn and/or undrawn nylon 6.6 fiber scraps including filament yarn is cut ranges from 3 cm to 5 cm to get nylon 6.6 chopped fibers. Chopped fibers feed to extruder to get the molten polymer from the scrap yarns. Molten polymer shaped to molten fiber in a certain diameter and cool in a water bath. After cooling of the fiber polymer, they cut in a certain size that called strand pelletizing system in the literature.

Vaccum is active during the tire grade recycled pellet production to remove the finish oil in the polymer matrix coming from the scrap oiled yam production process. It is very critical process for the production since the high finish oil level caused in low production yields and high break levels in spinning. Main aim is to minimize the finish oil level in the recycled pellet.

Since the tire grade recycled pellet and virgin pellet mixed during the production, homogenious mixing is another critical parameter in the preparation phase of the solid state polymerization. Pellet size of the two pellet grade need to be as much as close each other to prevent separation in the silos. So that, granulometry of the tire grade recycled pellet were improved for the tire grade recycled yam production. Tire grade recycled amount in the yarn depends on the customer expectations and minimum specification requirements. However according to “Global Recycling Certification” system, minimum requirement of the recycled amount is 20 % in the end product. So that according to this regulation, studies were focused to 20 % recycled material in the tire grade yam. Recycled pellet and virgin pellet was mixed and fed to silo for conditioning. Solid state polymerization was adjusted according to new mixtured raw material to get the same RV level at the end of the conditioner exit.