JP7728599B2 - How to recycle nonwoven waste - Google Patents

Description

The present invention relates to a method for recycling waste nonwoven fabric (waste nonwoven fabric) used as interior and exterior materials for automobiles.

In automotive applications, nonwoven fabrics have traditionally been used in interior materials such as floor carpets to reduce weight and provide soundproofing, and in recent years have also begun to be used in exterior materials such as fender liners and undercovers.

Nonwoven fabrics used in automotive interior and exterior materials must be recycled under the Automobile Recycling Law. Methods for recycling nonwoven fabrics used in automotive interior materials have been known for some time, and Patent Document 1 describes a method for recycling nonwoven fabrics used in automotive interior materials, specifically nonwoven fabrics made from specific resins.

Japanese Patent Application Laid-Open No. 2005-112930

In recent years, nonwoven fabrics used in automotive interior and exterior materials have come to be composed of multiple different types of resins, due to the increasing demand for lightweight and soundproofing properties. For this reason, the recycling method for nonwoven fabrics composed of specific resins described in Patent Document 1 has the problem that it cannot recycle waste nonwoven fabrics composed of multiple different types of resins.

The problem that the technology of this specification aims to solve was conceived in light of the above points, and aims to provide a method for recycling waste nonwoven fabrics used as interior and exterior automotive materials composed of multiple different types of resins.

The method for recycling nonwoven fabric waste according to an embodiment of the present specification is a method for recycling nonwoven fabric waste (nonwoven fabric waste) as an interior or exterior material for an automobile,
The nonwoven fabric waste material is composed of a plurality of different types of resins,
The method includes a crushing step of crushing the nonwoven fabric waste material by a crusher, and a pelletizing step of pelletizing the crushed nonwoven fabric waste material by a pelletizing device,
The pellet molding device is a flat die type pellet molding device, and the molding temperature in the pelletizing step is 75 to 130°C.

According to the method for recycling nonwoven fabric waste according to an embodiment of the present specification, even if the nonwoven fabric waste is composed of multiple different types of resin, the nonwoven fabric waste is crushed in the crushing process, resulting in a uniform mixture of the different types of resin. In the pelletizing process, the nonwoven fabric waste is heated to a molding temperature in a state in which the different types of resin are uniformly mixed, and the resin with the lowest melting point melts, making it possible to pelletize the nonwoven fabric waste. Therefore, even if the nonwoven fabric waste is composed of multiple different types of resin, it can be recycled.

Here, in the above-mentioned method for recycling nonwoven fabric waste, the pellets regenerated from the nonwoven fabric waste in the pelletizing process can be used as raw materials for fibers.

This allows nonwoven fabric waste to be recycled into fibers that can be used as raw materials for nonwoven fabric.

Furthermore, in the above-mentioned method for recycling nonwoven fabric waste, the pellets can be melt-spun into fibers.

Furthermore, in the above-mentioned method for recycling nonwoven fabric waste, the resin constituting the nonwoven fabric waste can be composed of polyester resin and polyolefin resin.

This allows the polyolefin resin, which has a low melting point, to be melted during the pelletizing process, while the polyester resin, which has a high melting point, can be pelletized without melting, thereby suppressing the decrease in molecular weight of the polyester resin due to thermal decomposition.

Furthermore, in the above-mentioned method for recycling nonwoven fabric waste, the polyester resin can be used to form fibers with a core-sheath structure, with the core being a high-melting-point polyester resin and the sheath being a low-melting-point polyester resin.

This allows the low-melting-point polyolefin resin and low-melting-point polyester resin to be melted during the pelletizing process, and the high-melting-point polyester resin can be pelletized without melting, thereby suppressing the decrease in molecular weight due to thermal decomposition of the polyester resin.

Furthermore, in the above-mentioned method for recycling nonwoven fabric waste, the resin constituting the nonwoven fabric waste can be composed of a high-melting point polyester resin and a low-melting point polyester resin.

This allows the low-melting-point polyester resin to be melted during the pelletizing process, while the high-melting-point polyester resin can be pelletized without melting it, thereby suppressing the decrease in molecular weight due to thermal decomposition of the polyester resin.

Furthermore, in the above-mentioned method for recycling nonwoven fabric waste, the crusher may be a uniaxial crusher.

This allows the nonwoven fabric waste to be crushed so that it is defibrated during the crushing process, resulting in a uniform mixture of different types of resin.

Furthermore, in the above-mentioned method for recycling nonwoven fabric waste, the crusher may be a guillotine cutter.

This allows the nonwoven fabric waste to be finely cut and crushed during the crushing process, resulting in a uniform mixture of different types of resin.

According to the embodiment of the method for recycling nonwoven fabric waste, nonwoven fabric waste can be recycled even if it is made up of multiple different types of resin.

FIG. 1 is an image diagram of a cycle of a method for recycling nonwoven fabric waste according to an embodiment.

The following describes a method for recycling nonwoven waste fabric according to an embodiment of this specification. Note that the scope of the present invention is not limited to the scope disclosed in the embodiment. The method for recycling nonwoven waste fabric according to the embodiment includes a crushing process in which nonwoven waste fabric composed of multiple different types of resins is crushed using a crusher, and a pelletizing process in which the crushed nonwoven waste fabric is pelletized using a pelletizing device. The crusher is a uniaxial crusher or a guillotine cutter, the pelletizing device is a flat die-type pelletizing device, and the molding temperature (die temperature) in the pelletizing process is 75 to 130°C.

As shown in Figure 1, the method for recycling nonwoven waste involves recycling nonwoven fabrics used in automobile interior and exterior materials, which are collected as interior and exterior waste materials after scrapping. The nonwoven fabrics are then processed into flakes in a crushing process, processed into resin pellets in a pelletizing process, and processed into resin fibers in a fiberizing process, before being recycled.

Resin fibers can be recycled into automotive interior and exterior materials by mixing them with the skeletal and adhesive fibers that make up the nonwoven fabric and thermoforming them. Thermoforming is carried out through a preliminary bonding process (nonwoven fabric production process) and a heat molding process (processing process). In the nonwoven fabric production process, the nonwoven fabric is heated to create an intermediate molded product called a moldable nonwoven fabric. In the processing process, the moldable nonwoven fabric produced in the nonwoven fabric production process is integrated into a molded product (interior and exterior materials) using a mold that is tailored to the installation location on the vehicle.

Recycled interior and exterior material waste can be mixed with resin fibers generated as processing waste during the nonwoven fabric and processing processes, respectively, so that the processing waste can also be recycled. The nonwoven fabric waste recycling method of this embodiment is also designed so that even processing waste alone can be recycled into flakes, resin pellets, resin fibers, or nonwoven fabric.

Nonwoven fabrics used as interior and exterior materials for automobiles are made from several different types of resins (fibers), consisting of skeletal fibers that form the framework and adhesive fibers that bond the skeletal fibers. Materials that can be used for the skeletal fibers include polyester resins (high-melting-point polyester resins) such as PET (polyethylene terephthalate) resin and PBT (polybutylene terephthalate) resin, and polyamide resin. In another embodiment, polyester resins with excellent heat resistance can be used, and in yet another embodiment, versatile PET resin can be used.

The skeletal fibers that make up the nonwoven fabric can be bonded together using adhesive fibers. The material that makes up the adhesive fibers has a lower melting point than the material of the skeletal fibers that make up the nonwoven fabric. Examples of materials that can be used include low-melting polyester resins such as low-melting PET resin (LPET) and low-melting PBT resin (LPBT), polyethylene resin, polypropylene resin, polystyrene resin, AS (acrylonitrile styrene) resin, ABS (acrylobutadiene styrene) resin, and acrylic resin.

The skeletal fibers and adhesive fibers that make up the nonwoven fabric can be fibers with a core-sheath structure, for example, with a polyester resin core and a low-melting-point polyester resin sheath. By using a core-sheath structure for the skeletal fibers and adhesive fibers, the fibers that make up the nonwoven fabric can be fused at low temperatures.

Nonwoven fabrics used as automotive interior materials are often multilayered to reduce weight and provide soundproofing, and some even include a resin film such as a perforated resin layer. Materials that can be used for the resin film include polyester resin, polyamide resin, polyethylene resin, polypropylene resin, polystyrene resin, AS resin, ABS resin, and acrylic resin. Resin film materials are selected appropriately to achieve weight reduction and soundproofing.

Nonwoven fabrics for automotive interiors are made by carding a mixture of skeletal fibers (including fibers with a core-sheath structure) and adhesive fibers to form a web (fibrous sheet). The web is then needle-punched, using tiny needle protrusions to entangle and bond the fibers. Nonwoven fabrics can be made into interior materials by thermoforming, if necessary, into multi-layer structures with resin films layered between them. Nonwoven fabrics can be made into interior materials by thermoforming. Thermoforming involves a pre-bonding process (nonwoven fabric formation process) and a heat-molding process (processing process). In the pre-bonding process, the nonwoven fabric is heated to form a moldable nonwoven fabric, which is an intermediate product. In the heat-molding process, the moldable nonwoven fabric formed in the pre-bonding process is integrated into an interior material (molded product) using a mold tailored to the installation location in the vehicle.

Nonwoven fabrics for automotive exteriors are used in areas exposed to water, so they require lightweight, soundproofing, and water resistance. For this reason, they contain a higher content of adhesive fibers than interior materials. Nonwoven fabrics for automotive exteriors are made by carding a mixture of skeletal fibers and adhesive fibers, or a mixture of core-sheath fibers and adhesive fibers, into a web, which is then needle-punched to form a nonwoven fabric by entangling the fibers with tiny needle protrusions. Nonwoven fabrics are then thermoformed into exteriors through a pre-bonding process and a heat molding process. By containing a higher content of adhesive fibers than interior materials, nonwoven fabrics for exteriors can have enhanced water resistance. Impregnating the surface of the nonwoven fabric with a synthetic resin can also enhance water resistance. The pre-bonding process involves heating the nonwoven fabric to form an intermediate molded product, a nonwoven fabric for molding. The heat molding process involves using a molded nonwoven fabric formed in the preliminary bonding process to create an integrated exterior material using a mold that is tailored to the installation location on the vehicle.

Nonwoven fabrics used as interior and exterior materials for automobiles are assembled on automobile production lines and used as part of the automobile. The method for recycling nonwoven waste materials according to the embodiment recycles nonwoven fabrics used in automobile interior and exterior materials that are collected as interior and exterior waste materials after the vehicle has been scrapped or after the interior and exterior materials have been replaced. The recycled interior and exterior waste materials can be mixed with resin fibers generated during the nonwoven fabric and processing steps as processing waste, and the processing waste can also be recycled. The method for recycling nonwoven waste materials according to the embodiment makes it possible to recycle only processing waste materials into flakes, resin pellets, resin fibers, or nonwoven fabric.

The collected nonwoven fabric waste has skeletal fibers and adhesive fibers with different resin compositions, and is composed of several different types of resin. The collected nonwoven fabric waste is processed into flakes in a crushing process, the flakes are processed into resin pellets in a pelletizing process, the resin pellets are processed into resin fibers in a fiberizing process, and the resin fibers are recycled into nonwoven fabric in a nonwoven fabric production process. The resin pellets can also be used as solid fuel.

The crushing process is a process in which nonwoven fabric waste is crushed into flakes 35 mm or less in size using a crusher. By crushing nonwoven fabric waste into flakes 35 mm or less in size and mixing them, multiple different types of resins (fibers) can be uniformly mixed, which allows resins with lower melting points to melt in the subsequent pelletizing process, thereby improving pelletization. In another embodiment, the crushing size can be 30 mm or less, and in yet another embodiment, 25 mm or less. Note that "35 mm or less" means that the outer diameter of the crushed flakes is a maximum of 35 mm or less. The crusher used in the crushing process can be a uniaxial (multiaxial) crusher or a guillotine cutter.

A single-shaft (or multi-shaft) shredder (hereinafter collectively referred to as a single-shaft shredder) is a shredder that cuts nonwoven waste material using rotating blades attached to the rotor shaft and fixed blades attached to the main body that contacts the rotor shaft. The shredded nonwoven waste material, or flakes, is crushed until it is large enough to pass through an outlet screen of the same size, and nonwoven waste material that cannot pass through the outlet screen is crushed multiple times until it is large enough to pass through. Examples of single-shaft shredders that can be used include the UC series, UFW series (manufactured by Uenotex Co., Ltd.), and SR series (manufactured by SSI Japan Co., Ltd.).

A guillotine cutter is a cutting machine that uses an axe-shaped blade to cut nonwoven waste material in a direction perpendicular to the direction of movement while the nonwoven waste material is being moved on a conveyor. Because the nonwoven waste material is cut into strips in a direction perpendicular to the direction of movement, a second cut is required to cut the strips in the short direction, with the longitudinal direction of the strips being the direction of movement, to produce flakes. The size of the nonwoven waste material can be determined by the conveyor speed and the number of cuts made per hour by the axe-shaped blade. Examples of guillotine cutters that can be used include the Guillotine Press Series (manufactured by Morita Environmental Tech Co., Ltd.) (Guillotine Press is a registered trademark), the C Series (manufactured by GeorDing Machinery), and the N Series (manufactured by Pierret).

The pelletization process involves applying pressure and heat to flakes made from crushed nonwoven fabric waste using a pellet molding device to turn them into resin pellets. The heated and pressurized flakes are forced by an extruder into a die with numerous small cylindrical holes, where they are formed into cylindrical flakes. Pellet molding devices are classified into flat die and screw types, depending on the pellet molding method. The flat die type uses a compression roller acting as an extruder to extrude flakes from the upper side of a flat die to the lower side of the die, and the molding temperature is 75 to 130°C. In another embodiment, the molding temperature can be 80 to 120°C. The screw type uses a screw acting as an extruder to extrude flakes into a die, and the molding temperature is 250 to 300°C. In the nonwoven fabric recycling method of this embodiment, a flat die type pellet molding device can be used, as the molding temperature is relatively low, thereby suppressing molecular weight reduction due to thermal decomposition of the skeletal fiber. Flat die pellet molding machines that can be used include the Flat Die Pellet Molding Machine (manufactured by KAHL), the EF4 Series (manufactured by Earth Engineering Co., Ltd.), and the Pellemake Series (manufactured by Kitagawa Iron Works Co., Ltd.).

Resin pellets recycled from waste automotive interior and exterior materials through the crushing and pelletizing processes can be regenerated into resin fibers through the fiberization process, and can also be used as solid fuel.

In the fiberization process, the resin pellets are mixed with resin pellets of other compositions, if necessary, and with a compatibilizer , using a twin-screw extruder-type melt spinning machine, and melt-spun to obtain undrawn yarns from the resin pellets. The undrawn yarns obtained from the resin pellets are drawn in warm water to obtain resin fibers. A compatibilizer is an additive added to mix different types of resins. An appropriate type of compatibilizer can be selected depending on the type of resins to be mixed.

As shown in Figure 1, resin fibers can be mixed with the skeletal fibers and adhesive fibers that make up the nonwoven fabric and thermoformed to form automotive interior and exterior materials. Thermoforming is carried out through a preliminary bonding process (nonwoven fabric formation process) and a heat molding process (processing process). In the preliminary bonding process, the nonwoven fabric is heated to form a moldable nonwoven fabric, which is an intermediate formed product. In the heat molding process, the moldable nonwoven fabric formed in the preliminary bonding process is integrated into an automotive interior or exterior material (molded product) using a mold that is tailored to the installation location on the vehicle.

The present invention will be explained in more detail below through examples.

Example 1
In Example 1, nonwoven fabric waste A used for automobile exterior materials was subjected to a crushing step and a pelletizing step to obtain resin pellets A from the nonwoven fabric waste A. The respective conditions are described below.

・Nonwoven waste material A
Two-layer structure: A1 layer (30mass%) + A2 layer (70mass%) A1 layer (PP (50mass%) / LPET (50mass%)) Core-sheath structure fiber 100mass%
A2 layer (PET (63mass%)/LPET (37mass%)) Core-sheath structural fiber 80mass%
PP fiber 20 mass%
Overall, PET fiber: LPET fiber: PP fiber = 35:36:29 (mass%)
Crushing process Crusher: Uniaxial crusher (SR series (manufactured by SSI Japan Co., Ltd.))
Exit screen: 28 mm
Pelletizing process Pellet forming equipment: EF4 series (manufactured by Earth Engineering Co., Ltd.)
Diameter of die hole: φ6 mm
Die temperature: 80°C
Resin pellets A were mixed with PET pellets in a mass ratio of 50:50 to obtain mixed pellets A. Mixed pellets A were melt-spun using a twin-screw extruder-type melt spinning machine (spinning temperature 300°C) to obtain unstretched yarn A from mixed pellets A. Unstretched yarn A was stretched four times in warm water at 80°C to obtain resin fiber A. Resin fiber A could be mixed with skeletal fibers and adhesive fibers that constitute a nonwoven fabric and thermoformed to form an automotive interior or exterior material.

Example 2
In Example 2, nonwoven fabric waste material B used for automobile exterior materials was subjected to a crushing step and a pelletizing step to obtain resin pellets B from the nonwoven fabric waste material B. The respective conditions are described below.

・Nonwoven waste material B
Two-layer structure: A1 layer (30mass%) + A2 layer (70mass%) A1 layer (PP (50mass%) / LPET (50mass%)) Core-sheath structure fiber 100mass%
A2 layer (PET (63mass%)/LPET (37mass%)) Core-sheath structural fiber 80mass%
PP fiber 20 mass%
Overall, PET fiber: LPET fiber: PP fiber = 35:36:29 (mass%)
Crushing process Crusher: Guillotine cutter (N series (Pierret))
Cutting interval: 25 mm (cutting in one direction and in a direction perpendicular to the one direction)
Pelletizing process Pellet forming equipment: EF4 series (manufactured by Earth Engineering Co., Ltd.)
Diameter of die hole: φ6 mm
Die temperature: 80°C
Resin pellets B were mixed with PET pellets in a mass ratio of 50:50 to obtain mixed pellets B. Mixed pellets B were melt-spun using a twin-screw extruder-type melt spinning machine (spinning temperature: 300°C) to obtain undrawn yarn B from mixed pellets B. Undrawn yarn B was stretched four times in warm water at 80°C to obtain resin fiber B.

Example 3
In Example 3, the resin pellets B obtained in Example 2 were mixed with PET pellets and an acid-modified compatibilizer in a mass ratio of 69:30:1 to obtain mixed pellets C. The mixed pellets C were melt-spun using a twin-screw extruder-type melt spinning machine (spinning temperature: 300°C) to obtain undrawn yarn C from the mixed pellets C. The undrawn yarn C was stretched four times in warm water at 80°C to obtain resin fiber C.

Example 4
In Example 4, automobile fender liner waste D, which is an automobile exterior material made of nonwoven fabric, was subjected to a crushing step and a pelletizing step to obtain resin pellets D from the nonwoven fabric waste D. The respective conditions are described below.

・Fender liner waste D
Two-layer structure: A1 layer (30mass%) + A2 layer (70mass%) A1 layer (PP (50mass%) / LPET (50mass%)) Core-sheath structure fiber 100mass%
A2 layer (PET (63mass%)/LPET (37mass%)) Core-sheath structural fiber 80mass%
PP fiber 20 mass%
Overall, PET fiber: LPET fiber: PP fiber = 35:36:29 (mass%)
Crushing process Crusher: Guillotine cutter (N series (Pierret))
Cutting interval: 20 mm (cutting in one direction and in a direction perpendicular to the one direction)
Pelletizing process Pellet forming equipment: EF4 series (manufactured by Earth Engineering Co., Ltd.)
Diameter of die hole: φ10 mm
Die temperature: 80°C
Resin pellets D were mixed with PET pellets in a mass ratio of 50:50 to obtain mixed pellets D. Mixed pellets D were melt-spun using a twin-screw extruder-type melt spinning machine (spinning temperature: 300°C), and undrawn yarn D was obtained from mixed pellets D. Undrawn yarn D was drawn four times in warm water at 80°C, to obtain resin fiber D.

Example 5
In Example 5, nonwoven fabric waste E from a three-layer floor carpet used as an interior material for automobiles was subjected to a crushing process and a pelletizing process to obtain resin pellets E from the nonwoven fabric waste E. The respective conditions are described below.

・Nonwoven waste material E
Three-layer structure: E1 layer (45.5mass%) + E2 layer (13mass%) + E3 layer (41.5mass%) E1 layer (PET (90mass%) / LPET (10mass%)) Core-sheath structure fiber 100mass%
E2 layer: Low density PE film 100 mass%
E3 layer (PET (70mass%)/LPET (30mass%)) Core-sheath structural fiber 100mass%
Overall, PET fiber: LPET fiber: PE film = 70:17:13 (mass%)
・Crushing process (1st time)
Crusher: Uniaxial crusher (UC series (manufactured by Uenotex Co., Ltd.))
Exit screen: 50 mm
・Crushing process (2nd time)
Crusher: Uniaxial crusher (UFW series (manufactured by Uenotex Co., Ltd.))
Exit screen: 20 mm
Pelletizing process Pellet forming equipment: EF4 series (manufactured by Earth Engineering Co., Ltd.)
Diameter of die hole: φ6 mm
Die temperature: 130°C
Resin pellets E were melt spun using a twin-screw extruder-type melt spinning machine (spinning temperature 300°C) to obtain unstretched yarn E from resin pellets E. Unstretched yarn E was stretched four times in warm water at 80°C to obtain resin fiber E. Resin fiber E could be mixed with skeletal fibers and adhesive fibers constituting a nonwoven fabric and thermoformed to form an interior or exterior material for an automobile.

Example 6
In Example 6, nonwoven fabric waste F used as an exterior material for automobiles was subjected to a crushing step and a pelletizing step to obtain resin pellets F from the nonwoven fabric waste F. The respective conditions are described below.

・Nonwoven waste material F
Single layer structure of F1 layer (100 mass%) F1 layer (PET (50 mass%) / LPET (50 mass%)) core-sheath structure fiber 100 mass%
Overall, PET fiber: LPET fiber = 50:50 (mass%)
Crushing process Crusher: Guillotine cutter (N series (Pierret))
Cutting interval: 20 mm (cutting in one direction and in a direction perpendicular to the one direction)
Pelletizing process Pellet forming equipment: EF4 series (manufactured by Earth Engineering Co., Ltd.)
Diameter of die hole: φ6 mm
Die temperature: 80°C
Resin pellets F were melt spun using a twin-screw extruder-type melt spinning machine (spinning temperature 300°C) to obtain undrawn yarn F from resin pellets F. Undrawn yarn F was drawn four times in warm water at 80°C to obtain resin fiber F.

Claims (6)

A method for recycling nonwoven fabric waste materials used as interior and exterior materials for automobiles, comprising:
The nonwoven fabric waste material is made up of a resin that is composed of a polyester resin with a high melting point and a polyester resin with a low melting point, or a polyester resin with a high melting point and a polyester resin with a low melting point and polypropylene, or a polyester resin with a high melting point and a polyester resin with a low melting point and polyethylene ,
The method includes a crushing process in which the nonwoven fabric waste is crushed by a crusher, a pelletizing process in which the crushed nonwoven fabric waste is pelletized by a pellet molding device, and a fiberizing process in which resin pellets recycled from the nonwoven fabric waste in the pelletizing process are melt-spun by a melt spinning machine to form fibers,
The resin fibers fiberized in the fiberization step are recycled into the nonwoven fabric as an interior or exterior material for the automobile,
The pellet molding device is a flat die type pellet molding device, and the die temperature, which is the molding temperature in the pelletizing step, is 75 to 130°C.
A method for recycling nonwoven fabric waste material. A method for recycling nonwoven fabric waste material as described in claim 1, characterized in that the polyester resin with a high melting point and the polyester resin with a low melting point form fibers with a core-sheath structure, the core being the polyester resin with a high melting point and the sheath being the polyester resin with a low melting point . 3. The method for recycling nonwoven fabric waste material according to claim 1, wherein the resin pellets are mixed with pellets of other resin compositions and then melt-spun into fibers in the fiber-forming step. 3. The method for recycling nonwoven fabric waste material according to claim 1, wherein the resin pellets are mixed with pellets of another resin composition and a compatibilizer, and then melt-spun into fibers in the fiber-forming step. 3. The method for recycling nonwoven fabric waste material according to claim 1, wherein the crusher is a uniaxial crusher. 3. The method for recycling nonwoven fabric waste material according to claim 1, wherein the crusher is a guillotine cutter.