JP4292452B2 - Recycled pellet manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
Since the present invention reuses the end material after punching the product from the base fabric of the airbag mainly made of polyamide fabric and the base fabric material of the discarded airbag, the base fabric is efficiently pulverized and melted. The present invention relates to a method for producing regenerated pellets by kneading.
[0002]
[Prior art]
Airbags, especially automobile airbags, have all started to be installed in new cars to ensure the safety of drivers and passengers. These air bag materials were originally developed with various materials, but recently, they are being unified into a base fabric based on polyamide fabric, particularly nylon 66 fabric. This is because the excellent toughness and heat resistance of the nylon 66 woven fabric have been recognized as optimal as an air bag material. The base fabric based on nylon 66 fabric for airbags, which has begun to be used in large quantities, has a problem of recycling because many scraps are generated as waste in the airbag manufacturing process. In addition, it is expected that a large amount of used automobile air bags will be generated in the future, and the treatment will be a big problem in the future. Therefore, it is necessary to recycle the air bag base fabric based on a tough polyamide fabric.
[0003]
Until now, industrial pulverization of fabrics made of tough and flexible synthetic fibers has been extremely difficult. When these woven fabrics are pulverized by many pulverizers whose main pulverization force is the shear force generated between the rotary blade and the fixed blade, which is often used for pulverizing plastic molded products, the fibers can be completely cut. It was difficult to draw the fibers from the crusher by drawing the fibers into a string or cotton shape. Further, these cotton-like lumps are very bulky, so that biting failure occurs in a hopper such as an extruder, and melting and regenerating pelletization are impossible.
[0004]
In addition, the base fabric of an automobile air bag can be pulverized by cooling it with liquid nitrogen or the like to freeze brittle and making the nylon 66 fabric brittle, but it is industrially expensive because the refrigerant such as liquid nitrogen is expensive. Manufacture is impossible.
On the other hand, as a conventional cutting machine for cutting cloth, the cloth is cut between two flat blades, but when the two flat blades are closed, the floating cloth is not fixed. In order to escape gradually, it is necessary to cut while holding the cloth in some way. In addition, as the cloth to be cut becomes stronger, the force by which the cloth escapes and moves more and more increases. With such a cutter, it has been difficult to continuously cut a tough fabric into small pieces.
[0005]
[Problems to be solved by the invention]
The present invention was made against the background of these prior art problems, and continuously grinds the end material and waste of a tough automotive air bag base fabric into small pieces, improving the bite in a hopper such as an extruder, The object is to produce recycled pellets from waste at low cost by continuous melting, kneading and pelletization.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the inventors have finally completed the present invention. That is, the present invention (1) in the manufacturing method of a regenerated pellet in which the end material and waste material of an air bag base fabric are pulverized into small pieces, and the small pieces are melt-kneaded to form pellets, A cutting machine comprising a blade and a fixed flat blade , wherein both ends of a fabric to be cut are fixed after being in contact with both ends of a movable movable upper blade having a concave shape, and a method for producing a regenerated pellet characterized by cutting . (2) The method for producing a regenerated pellet according to (1) , wherein the small piece is a small piece of 5 × 5 cm square or less, and the small piece is smaller than a screw diameter for pelletizing. (3) The method for producing recycled pellets according to (1), wherein the airbag base fabric is a polyamide fabric. (4) The method for producing recycled pellets according to claim 1, wherein the airbag base fabric is a nylon 66 woven fabric. (5) The method for producing recycled pellets according to (1), wherein the airbag base fabric is a laminated composite sheet made of a polyamide woven fabric and an olefin-based sheet. (6) The method for producing recycled pellets according to (1), wherein the airbag base fabric is a composite sheet obtained by coating a polyamide fabric with a resin. (7) The method for producing recycled pellets according to (1), wherein the airbag base fabric is for automobiles.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be specifically described below.
FIG. 1 is a front view showing a portion of a cutting blade which is a point of a cutting machine according to an embodiment used when carrying out the method of the present invention.
In FIG. 1, 1 is a movable upper blade, and 2 is a fixed blade. The movable upper blade can change the movable range depending on the width of the fabric to be cut. When cutting the fabric, both ends of the fabric are fixed in contact with both ends of the movable upper blade having a concave shape. Therefore, even if the fabric is moved by force applied to the fabric during cutting, the movement is fixed. Even if the fabric is not inserted into the center of the blade, when the concave upper blade moves downward, the fabric touches one end of the fabric and the fabric is pushed and moves laterally, and both ends of the fabric are concave upper blade. It touches both ends and is fixed.
That is, since both ends of the fabric are always fixed at the start of cutting, the fabric can be freely cut with a predetermined size.
In the present invention, the concave shape is not particularly limited, and any shape may be used as long as the fabric is first fixed by both ends of the concave blade. For example, although it has an arc shape in FIG. 1, it may be a triangle or a trapezoid.
In addition, it is possible to continuously cut small pieces by continuously moving the fabric to be cut so as to interlock with the movable upper blade by attaching a driving roll behind the cutting blade of the cutting machine. .
[0008]
In the present invention, it is preferable that the cut size of the base fabric mainly composed of polyamide fabric is a small piece of 5 × 5 cm square or less. When the size of the cut piece becomes larger than this, a bridge is generated in a hopper such as an extruder for melt kneading and the biting of the screw of the extruder is deteriorated, so that stable melt kneading becomes difficult. Although related to the type of the extruder and the size of the screw, in order to produce a stable recycled pellet, it is preferable to grind into small pieces with a cutting size of 5 × 5 cm square or less, particularly 4 × 4 cm square or less.
[0009]
The air bag base fabric mainly composed of polyamide fabric in the present invention is a base fabric in which several polyamide fabrics are stacked, or a laminated composite sheet in which a polyamide fabric and a thin sheet made of polyethylene, polyethylene / polyolefin copolymer, etc. are laminated. The base fabric and the base fabric coated with a resin such as a silicone resin, a urethane resin, or a vinyl acetate resin on the surface so as to cover the mesh of the base fabric and the polyamide fabric. In addition, air bags for automobiles must operate properly even after several years have passed since installation in each automobile, and the base fabric is made of a lubricant such as silicone so that the airbag can be inflated correctly in the event of an accident. It is common.
In the present invention, an air bag base fabric mainly composed of all these types of polyamide fabrics can be used.
[0010]
The polyamide resin constituting the polyamide fabric in the present invention has an acid amide bond (—CONH—) in the molecule. Specifically, ε-caprolactam, 6-aminocaproic acid, ω-enantolactam, 7 Polymers or copolymers obtained from aminoheptanoic acid, 11-aminoundecanoic acid, 9-aminononanoic acid, α-pyrrolidone, α-piperidone, etc .: hexamethylenediamine, nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine Examples thereof include polymers or copolymers obtained by polycondensation of diamines such as metaxylylenediamine and dicarboxylic acids such as terephthalic acid, isophthalic acid, adipic acid, and sebacic acid, or blends thereof. However, it is not limited to these.
In the present invention, nylon 6 obtained from ε-caprolactam and nylon 66 obtained from hexamethylenediamine and adipic acid are preferred, and nylon 66 is particularly preferred.
[0011]
Examples of the airbag base fabric in the present invention include airbag base fabrics used for automobiles, motorcycles, and other various applications. In the present invention, a tough automotive airbag base fabric is preferable.
[0012]
As a device for melting, kneading and pelletizing a small piece of an air bag base fabric crushed in the present invention, a single-screw extruder, a twin-screw extruder, a kneader, a pressure kneader, a Banbury, and a compression molding machine using compression friction heat Etc. can be mentioned.
Among these apparatuses, a single screw extruder or a twin screw extruder is particularly preferable. A single-screw or twin-screw extruder can continuously produce recycled pellets, which is the most efficient production method with low labor costs. In order to perform stable operation using these extruders, it is necessary to optimize the size of the crushed pieces of the automobile air bag base fabric and the screw diameter of the extruder. If the screw diameter is smaller than that of the pulverized small piece, the bite into the screw becomes unstable and operation trouble occurs. In general, the size of a piece to be cut is determined depending on the size of an extruder to be used. As described above, even if the extruder to be used is large, a small piece of 5 × 5 cm square or more is not preferable because the bite into the bridge or screw in the hopper becomes unstable.
[0013]
In the present invention, if necessary, a compatibilizing agent may be added in order to improve the compatibility between the polyamide resin and other resin mixed therein. For example, in a base fabric made of nylon 66 woven fabric and olefin sheet, if a small amount of maleic acid-modified olefin resin is added in the extrusion process, compatibility between nylon 66 and olefin resin is improved, and recycled pellets with excellent uniformity are produced. I can do it.
[0014]
Moreover, the inorganic substance for reinforcement | strengthening can be mix | blended with resin by an extrusion process as needed. For example, fibrous reinforcing materials such as glass fiber, carbon fiber, ceramic fiber, and various whiskers. Examples thereof include powdery inorganic reinforcing materials such as silica, alumina, talc, kaolin, quartz, mica, and powdered glass. These reinforcing inorganic materials may be treated with a silane coupling agent as a surface treatment agent. Furthermore, carbon black and copper antioxidants and / or alkali metal halides that are weather resistance improvers used in ordinary nylon resins, phenolic antioxidants, phosphorus antioxidants, flame retardants as light or heat stabilizers , Mold release agents, lubricants, antistatic agents, pigments, dyes and the like can be blended.
[0015]
In the present invention, the end material and waste of an automobile air bag base fabric mainly composed of a polyamide fabric having toughness is crushed into small pieces, the biting property with a hopper or screw such as an extruder is improved, and stable melting, Kneading and pelletization became possible, and recycled pellets could be manufactured at low cost from waste.
[0016]
【Example】
EXAMPLES Next, the present invention will be specifically described using examples, but the present invention is not limited to these examples.
A base fabric made of a 5-layer laminated sheet of {nylon 66 woven fabric / high density polyethylene (HDPE) sheet / nylon 66 woven fabric / HDPE sheet / nylon 66 woven fabric} was used as an automotive airbag base fabric, and an automotive airbag was punched out. The end material width of the subsequent base fabric was a long sample having a width of about 30 to 50 cm.
[0017]
The base fabric cutting machine used was “Fiber cutting machine HP-600” (manufactured by Sakai Seisakusho), and two of these cutting machines were used. The cutting method of the base fabric is first cut into 4 × 30 to 50 cm by the above cutting machine, and then the primary cutting base fabric is conveyed by a conveyor belt, and the primary cutting base fabric is dropped on the next conveyor belt whose direction is changed by 90 degrees, The base fabric was cut into small pieces of about 4 × 3 cm square by a second cutter at the tip of the conveyor belt. The cutting condition of the base fabric of these two cutting machines was very smooth, and the cutting amount of the small piece of base fabric per hour was about 100 kg.
Further, when the weight ratio of nylon 66 and HDPE was measured from the cut pieces of the base fabric, nylon 66: 92% by weight and HDPE: 8% by weight were measured.
[0018]
Next, melt kneading and pelletization were carried out with a 60φ twin screw extruder.
Since 8% by weight of HDPE is mixed in the airbag base fabric for automobiles, 4 parts by weight of maleic acid-modified ethylene / propylene resin is added as a compatibilizer for nylon 66 and HDPE per 100 parts by weight of the base fabric. It put into the hopper of the shaft extruder.
The twin screw extruder was melt kneaded at a cylinder temperature of 250 ° C. to 290 ° C. There was no hopper clogging of the base fabric piece, and the screw bite was good, and a stable and uniform strand was obtained from the nozzle of the twin screw extruder. The recycled pellets had a shape of about 2.5 mmφ × 3 mm. The discharge rate of this twin screw extruder was about 150 kg / H.
[0019]
Next, physical properties of the obtained recycled pellets mainly composed of nylon 66 were evaluated.
Test pieces for evaluating physical properties according to ASTM were molded by an injection molding machine, and main physical property values were measured. The test piece was molded under the conditions of cylinder temperature: 290 ° C. and mold temperature: 80 ° C.
Physical properties Tensile strength: 60 MPa, Tensile elongation: 110%,
Flexural strength: 80 MPa, flexural modulus: 1.8 GPa
Impact strength: 180J / m
These physical property values are almost the same as or better than virgin nylon 66, and are extremely excellent recycled pellets.
[0020]
【The invention's effect】
The present invention aims to recycle the end material of an automobile airbag base fabric that has been discarded without being reused up to now and the used automobile airbag that is considered to be discarded in large quantities in the future. The base fabric end material was pulverized into small pieces, studied for melting, kneading, and recycling pelletization, and an industrial manufacturing method was established. The recycled polyamide pellets are also equivalent to or better than polyamide, especially nylon 66 virgin pellets, and can be used as engineering plastic materials in many fields such as architecture, electricity, electronics, automobiles and sports goods. It is great to contribute to the industry.
[Brief description of the drawings]
FIG. 1 is a front view showing a part of a cutting blade according to an embodiment used when carrying out a method of the present invention.
[Explanation of symbols]
1: concave movable blade (upper blade)
2: Fixed flat blade (lower blade)

Claims (7)

A flat blade fixed to a concave movable blade when pulverized into small pieces in a method of producing a regenerated pellet in which the end material and waste material of an air bag base fabric are pulverized into small pieces, and the small pieces are melt-kneaded into pellets A method for producing recycled pellets, characterized in that both ends of a fabric to be cut are in contact with and fixed to both ends of a concave movable upper blade and cut . The method for producing a regenerated pellet according to claim 1, wherein the small piece is smaller than a screw diameter for pelletizing at 5 x 5 cm square or less. The method for producing recycled pellets according to claim 1, wherein the airbag base fabric is a polyamide woven fabric. The method for producing a regenerated pellet according to claim 1, wherein the air bag base fabric is a nylon 66 woven fabric. 2. The method for producing recycled pellets according to claim 1, wherein the airbag base fabric is a laminated composite sheet comprising a polyamide woven fabric and an olefin-based sheet. The method for producing regenerated pellets according to claim 1, wherein the air bag base fabric is a composite sheet obtained by coating a polyamide woven fabric with a resin. The method for producing regenerated pellets according to claim 1, wherein the air bag base fabric is for automobiles.

Images