PLASTIC FOAM PRODUCT ADDED WITH EVA RECYCLED PELLETS AND METHOD OF MANUFACTURING SAME

Abstract

Proposed are a plastic foam product added with EVA recycled pellets and a method of manufacturing the same, in which there is provided a process for manufacturing a shoe sole by recycling shoe molding waste generated due to defective judgment during a shoe manufacturing process and used shoe waste discarded after use of finished shoe products, thereby allowing shoe manufacturing to meet the trend of pursuing eco-friendly products in Korea and in markets such as Europe, and there is provided a process in which dispersion between materials is strengthened in the process of manufacturing a plastic foam product by adding EVA recycled pellets to an EVA foam compound and mixing them with each other, thereby enabling uniform foaming and thus realizing a good shape and improving the strength and quality of the product.

Claims

1. A method of manufacturing a plastic foam product added with EVA recycled pellets, the method comprising: forming EVA recycled pellets by crushing EVA foam waste by a crushing device; preparing an EVA foam compound from an EVA raw material; adding the EVA recycled pellets to the EVA foam compound; primarily mixing and dispersing the EVA foam compound and the EVA recycled pellets in a high viscosity state at a set rotation speed by a kneader under a set processing temperature condition; secondarily mixing and dispersing the primarily mixed and dispersed EVA foam compound and EVA recycled pellets while inputting the primarily mixed and dispersed EVA foam compound and EVA recycled pellets into a roll mill; and forming a final plastic foam product by injecting the mixed and dispersed EVA foam compound and EVA recycled pellets in a molten state into a foam mold to form a semi-finished plastic foam product and then inputting the semi-finished plastic foam product into a press mold and press-molding the semi-finished plastic foam product.

2. The method of claim 1, wherein the final plastic foam product is a shoe sole, and the EVA foam waste includes shoe molding waste generated in a shoe manufacturing process and used shoe waste discarded after use of finished shoe products.

3. The method of claim 2, further comprising: after the forming of the final plastic foam product, collecting a defective product while inspecting plastic foam products; and inputting the collected defective product into the crushing device by using the collected defective product as the EVA foam waste.

4. The method of claim 1, wherein the forming of the EVA recycled pellets is performed by forming EVA recycled pellets having a diameter of 3 to 6 mm by the crushing device, the adding of the EVA recycled pellets to the EVA foam compound is performed by adding 15 to 25 wt % of the EVA recycled pellets to 75 to 85 wt % of the EVA foam compound, and the primarily mixing and dispersing of the EVA foam compound and the EVA recycled pellets and the secondarily mixing and dispersing of the EVA foam compound and the EVA recycled pellets are performed by mixing and dispersing the EVA foam compound and the EVA recycled pellets under a processing temperature condition of 85? C. to 95? C.

5. The method of claim 1, further comprising: after the adding of the EVA recycled pellets to the EVA foam compound and before the primarily mixing and dispersing of the EVA foam compound and the EVA recycled pellets, adding additives for improving compatibility, improving dispersibility of recycled scraps, and uniformizing physical properties to a mixture of the EVA foam compound and the EVA recycled pellets.

6. A plastic foam product added with EVA recycled pellets, the plastic foam product being manufactured by the method of claim 1.

7. A plastic foam product added with EVA recycled pellets, the plastic foam product being manufactured by the method of claim 2.

8. A plastic foam product added with EVA recycled pellets, the plastic foam product being manufactured by the method of claim 3.

9. A plastic foam product added with EVA recycled pellets, the plastic foam product being manufactured by the method of claim 4.

10. A plastic foam product added with EVA recycled pellets, the plastic foam product being manufactured by the method of claim 5.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other objectives, features, and other advantages of the present disclosure will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings, in which:

[0023] FIG. 1 is a basic flow block diagram illustrating a method of manufacturing a plastic foam product added with EVA recycled pellets according to the present disclosure;

[0024] FIG. 2 is a flow block diagram illustrating a method of manufacturing a plastic foam product added with EVA recycled pellets according to an embodiment of the present disclosure;

[0025] FIG. 3 is a view illustrating the method of manufacturing the plastic foam product added with the EVA recycled pellets according to the embodiment of the present disclosure;

[0026] FIG. 4 is a view illustrating a shoe sole that is a plastic foam product added with EVA recycled pellets according to the present disclosure; and

[0027] FIG. 5 is a view illustrating the configuration of a crushing device at a defective product crushing device inputting step according to the embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Meanwhile, in the drawings and specification, configurations and operations that can be easily understood by those skilled in the art will be briefly illustrated or omitted. In particular, in the drawings and specification, illustrations and descriptions of technical configurations and operations directly unrelated to the technical features of the present disclosure will be omitted, and only the technical configurations related to the present disclosure will be briefly illustrated or described.

[0029] As illustrated in FIG. 1, a method of manufacturing a plastic foam product added with EVA recycled pellets according to an embodiment of the present disclosure includes an EVA recycled pellet forming step, an EVA foam compound preparing step, a recycled pellet added foam compound forming step, an EVA foam compound/recycled pellet primary mixing/dispersing step, an EVA foam compound/recycled pellet secondary mixing/dispersing step, and a plastic foam product manufacturing step.

[0030] The EVA recycled pellet forming step is a step in which EVA foam waste is crushed by a crushing device 100 to form EVA recycled pellets. Here, the EVA foam waste may include shoe molding waste generated in a shoe manufacturing process and used shoe waste discarded after use of finished shoe products. In addition, a final plastic foam product manufactured according to the present disclosure may be a shoe sole. In the EVA recycled pellet forming step according to the embodiment of the present disclosure, EVA recycled pellets having a diameter of 3 to 6 mm are formed by the crushing device 100. When the particle size of the EVA recycled pellets is larger than the diameter size of 3 to 6 mm, dispersion may not occur smoothly when mixing an EVA foam compound and the EVA recycled pellets. When the particle size of the EVA recycled pellets is smaller than the diameter size of 3 to 6 mm, the EVA recycled pellets may fly away when mixing the EVA foam compound and the EVA recycled pellets, and mixing may not occur smoothly.

[0031] Meanwhile, as illustrated in FIG. 2, the method of manufacturing the plastic foam product added with the EVA recycled pellets according to the embodiment of the present disclosure further includes a defective product collecting step and a defective product crushing device inputting step after the plastic foam product manufacturing step.

[0032] The defective product collecting step is a step in which a defective product is collected while inspecting plastic foam products. The defective product crushing device inputting step is a step in which the collected defective product is input into the crushing device 10 by using collected defective product as the EVA foam waste. Here, as illustrated in FIG. 5, the crushing device 10 according to the embodiment of the present disclosure into which the defective product collected in the defective product crushing device inputting step is input includes a hopper 100, a main body frame 200, a cutter unit 300, a drive motor 400, a centrifugal pump 500, a collection container 600, and a controller 800. The crushing device 10 is a device that is effectively applied to manufacturing pellets for recycling defective soft EVA shoe soles. A crushing device having the configuration disclosed in Korean Patent Application Publication No. 10-2022-0185396, entitled Crushing Device for Manufacturing EVA Recycled Pellets filed by the present applicant, may be used in the method of manufacturing the plastic foam product added with the EVA recycled pellets according to the embodiment of the present disclosure.

[0033] The EVA foam compound preparing step is a step in which an EVA foam compound is prepared from an EVA raw material. The EVA foam compound is a general foam compound prepared using an EVA raw material used in foam molding of general shoe soles.

[0034] The recycled pellet added foam compound forming step is a step in which the EVA recycled pellets are added to the EVA foam compound. Here, in the recycled pellet added foam compound forming step according to the embodiment of the present disclosure, 15 to 25 wt % of the EVA recycled pellets are added to 75 to 85 wt % of the EVA foam compound. When the amount of EVA recycled pellets added is too large, the dispersing power decreases when mixing materials, resulting in poor quality, and when the amount thereof is too small, recyclability decreases.

[0035] Meanwhile, the method according to the present disclosure may further include an additive adding step after the recycled pellet added foam compound forming step and before the EVA foam compound/recycled pellet primary mixing/dispersing step. In the additive adding step according to the embodiment of the present disclosure, 1 to 5 wt % of a compatibilizer, 1 to 3 wt % of a lubricant, and 5 to 10 wt % of calcium carbonate are added to a mixture of the EVA foam compound and the EVA recycled pellets. The adding of the additives leads to improved compatibility, improved dispersibility of recycled scraps, and uniform physical properties.

[0036] The EVA foam compound/recycled pellet primary mixing/dispersing step is a step in which the EVA foam compound and the EVA recycled pellets in a high viscosity state are primarily mixed and dispersed at a set rotation speed by a kneader 200 under a set processing temperature condition. Here, in the EVA foam compound/recycled pellet primary mixing/dispersing step according to the embodiment of the present disclosure, the EVA foam compound and the EVA recycled pellets are mixed and dispersed under a processing temperature condition of 85? C. to 95? C. As mixing is performed at a high rotation speed of 60 to 75 rpm at a lower processing temperature of 85? C. to 95? C. compared to a conventional recycling process, a dispersion strengthening effect due to high shear force is obtained.

[0037] The EVA foam compound/recycled pellet secondary mixing/dispersing step is a step in which the primarily mixed and dispersed EVA foam compound and EVA recycled pellets are secondarily mixed and dispersed while inputting them into a roll mill 300. In the EVA foam compound/recycled pellet secondary mixing/dispersing step, the EVA foam compound and the EVA recycled pellets are mixed and dispersed under a processing temperature condition of 85? C. to 95? C. as in the EVA foam compound/recycled pellet primary mixing/dispersing step. As mixing is performed at a high rotation speed of 60 to 75 rpm at a lower processing temperature of 85? C. to 95? C. compared to a conventional recycling process, a dispersion strengthening effect due to high shear force is obtained. Through the EVA foam compound/recycled pellet primary mixing/dispersing step compound/recycled pellet secondary and the EVA foam mixing/dispersing step, the EVA recycled pellets are evenly dispersed in the EVA foam compound, creating a core-cell structure in which EVA foam compound particles homogeneously disperse and surround EVA recycled pellet particles. This enables uniform foaming during the plastic foam product manufacturing step, thereby realizing a good shape and improving the strength and quality of the product.

[0038] The plastic foam product manufacturing step is a step in which the mixed and dispersed EVA foam compound and EVA recycled pellets in a molten state are injected into a foam mold 40 to form a semi-finished plastic foam product, and then the semi-finished plastic foam product is input into a press mold 50 and press-molded to form a final plastic foam product such as a shoe sole 1 illustrated in FIG. 4.

[0039] According to the plastic foam product added with the EVA recycled pellets and the method of manufacturing the same according to the embodiments of the present disclosure configured as described above, there is provided a process for manufacturing a shoe sole by recycling shoe molding waste or used shoe waste through the EVA recycled pellet forming step, the EVA foam compound preparing step, the recycled pellet added foam compound forming step, the EVA foam compound/recycled pellet primary mixing/dispersing step, the EVA foam compound/recycled pellet secondary mixing/dispersing step, and the plastic foam product manufacturing step, thereby allowing shoe manufacturing to meet the trend of pursuing eco-friendly products in Korea and in markets such as Europe. In addition, according to the plastic foam product added with the EVA recycled pellets and the method of manufacturing the same according to the embodiments of the present disclosure, there is provided a process in which dispersion between materials is strengthened in the process of manufacturing the plastic foam product by adding the EVA recycled pellets to the EVA foam compound and mixing them with each other, thereby enabling uniform foaming and thus realizing a good shape and improving the strength and quality of the product.

[0040] Although the preferred embodiments of the plastic foam product added with the EVA recycled pellets and the method of manufacturing the same according to the present disclosure have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions, and substitutions are possible, without departing from the scope and spirit of the present disclosure as disclosed in the accompanying claims.