JP3134095B2 - Fiber recovery and reuse method from fiber reinforced plastic - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is widely used in the transportation industry and the chemical industry, for example, for fiber reinforced plastics such as glass fiber reinforced plastics or carbon fiber reinforced plastics used for structural materials of ships, aircrafts and the like. More particularly, the present invention relates to a technology for decomposing a polymer component of a fiber reinforced plastic to a low molecular level, separating and collecting a reinforced fiber component for reuse.

[0002]

2. Description of the Related Art Plastics, which are not found in metallic materials such as iron and aluminum and have excellent light weight or chemical stability, are used in all industrial fields and daily life fields. In places requiring strength, such as structural materials for ships and aircraft, fiber-reinforced plastics containing carbon fiber, glass fiber, or the like as a reinforcing material are widely used.

[0003] Under such circumstances, a large amount of fiber-reinforced plastic waste materials that are aged and discarded are now being generated. At present, these waste materials are mainly treated by incineration and landfill.

[0004] Further, a treatment method utilizing a hydrolysis reaction with high-temperature steam has also been proposed, and by this method, organic polymer components of thermoplastic plastics and thermosetting plastics can be decomposed temporarily.

[0005] Further, there is an example in which these fiber reinforced plastics are crushed and used as a filler for building materials and plastic household goods.

[0006]

However, with respect to landfill treatment, it is becoming difficult to secure landfill sites, and landfilling of fiber-reinforced plastics that do not decompose semi-permanently has been regarded as a problem.

On the other hand, the treatment by incineration may cause secondary disasters due to the generation of black smoke, harmful gas or odor.
Further, since heating is performed at a high temperature of about 820 ° C. or more, there is a problem that the incinerator is significantly damaged and its life is shortened.

[0008] In the utilization of the hydrolysis reaction using high-temperature steam, organic components often remain in the fibers, and the separated reinforcing fibers such as glass and carbon cannot be reused as they are.

Further, it has been pointed out that such a process of pulverizing fiber-reinforced plastic may cause dust such as glass fibers generated at the time of pulverization to cause the same problem of carcinogenicity as asbestos. Is quite problematic.

However, at present, there is no appropriate processing method to solve these problems.

Accordingly, the present invention provides a fiber reinforced plastic which can be separated, recovered and reused efficiently without discharging toxic decomposition products out of the system and without damaging the reinforcing fibers in the fiber reinforced plastic waste material. And a method for recovering and reusing the fiber from the product.

[0012]

According to the present invention , a fiber is provided in a reactor.
Filled with fiber reinforced plastic, decompressed to remove air,
Subsequently, Ar gas is sealed and brought to atmospheric pressure, the fiber-reinforced plastic is contacted and reacted with supercritical water or subcritical water in the reactor, and fibers such as glass fiber or carbon fiber are separated and recovered from the fiber-reinforced plastic. And reuse.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a method of controlling the pH of a system by adding water to a fiber reinforced plastic such as glass fiber reinforced plastic or carbon fiber reinforced plastic, controlling the pH of the system, and increasing the temperature to increase the critical pressure. Point (3
An organic polymer such as a thermoplastic or thermosetting plastic in the fiber reinforced plastic waste material by reaching a subcritical state of 74.4 ° C. or lower than 22.1 MPa) or a supercritical temperature and pressure higher than that. Breaks down components to low molecular levels.

[0014]

Further, in order to prevent partial hydrolysis of the fiber, it is preferable to set the pH of the supercritical water or the subcritical water to a neutral range of 4 to 8.

Further, in a reaction system in a neutral region, hydrolysis is promoted by utilizing a catalyst such as a metal hydrogencarbonate that provides hydrogen ions or hydrogen ions generated from a decomposition product such as a thermosetting resin. You may.

By setting the reaction temperature in the range of 320 to 500 ° C., the surface of the glass fiber or carbon fiber can be sufficiently purified to the extent that it can be reused. Normal,
Even at a temperature of 300 ° C or less, it is possible to decompose the organic polymer component of the thermoplastic or thermosetting plastic, but since the organic component remains in the fiber, it must be reused as it is. Can not. Also, 50
If the temperature is raised to a temperature exceeding 0 ° C., glass fibers or carbon fibers themselves are partially damaged by hydrolysis or the like, and thus cannot be reused. Therefore, when separating and recovering and reusing the reinforcing fiber component, the reaction temperature is set at 32.
By setting the temperature in the range of 0 to 500 ° C. and controlling the temperature, chemical recycling of glass fibers or carbon fibers from waste fiber reinforced plastics becomes possible.

FIG. 1 is a diagram of a fiber-reinforced plastic decomposition / recovery system using supercritical water to which the present invention is applied. A fiber-reinforced plastic such as glass fiber-reinforced plastic or carbon fiber-reinforced plastic is placed in a decomposition tank 1 serving as a reactor. At the same time, water is supplied from the water cylinder 2 to the water tank 3,
After water is charged into the decomposition tank 1 by the high-pressure pump 4, the valves 5 and 6 are closed to completely seal the decomposition tank 1. In this case, the amount of water to be added is 1 to 50% by volume with respect to the decomposition tank 1.
The degree is suitable.

Thereafter, the heat exchanger 8 and the decomposition tank 1 are externally heated by the constant temperature bath 7 so that
The temperature in the decomposition tank 1 is raised to a predetermined temperature of ° C to bring the water in the decomposition tank 1 into a subcritical / supercritical state.

In the above process, after maintaining the water in a subcritical / supercritical state for a predetermined time, the temperature is returned to normal temperature, and the valve 6
Is opened, and a gas portion having a low boiling point such as hydrocarbons such as methane, ethylene, ethane, propane or propylene, carbon dioxide, and nitrogen is separated and collected through the trap 9. At room temperature, alcohols such as methanol, ethanol and propanol which are liquids, amines such as methylamine, ethylamine and propylamine generated from amine-based nitrogen-containing compounds used as a cross-linking agent, and plastics are formed. Separation and recovery of water and monomers such as styrene and phthalic acid and their decomposed products. Further, the vitreous or carbonaceous fibers generated at a predetermined reaction temperature are collected by filtration with a suitable filter.

In the decomposition tank, at least a liquid phase and a solid phase are separated, and an oily component and a glass fiber component can be completely separated and recovered. Further, the gas phase was recovered without being taken out of the system, and analyzed by a gas chromatograph-mass spectrometer. As a result, it was confirmed that the gas was decomposed into several tens of gaseous compounds.

FIG. 2 is a scanning electron micrograph of an unused reinforcing fiber and a processed reinforcing fiber, and FIGS. 2- (a) and (b)
When the unused reinforcing fiber shown in Fig. 2 is compared with the reinforcing fiber collected by processing the fiber-reinforced plastic shown in Figs. 2- (c) and (d), there is no difference between the two. No extra organic matter was attached to these fibrous compounds. Therefore, it was confirmed that the reinforcing fibers recovered after the treatment were completely purified fibers. In addition, the collected reinforcing fibers can not only be reused as reinforcing fibers for building reinforced plastics,
In addition, it can be used as a heat insulating material, a soundproofing material, or an adsorbent.

Therefore, in the present invention, it is possible to decompose these fiber reinforced plastics to a low molecular level, but the composite material is not only fiber but also fiber.
It can be applied to any form of material, for example, it can be applied to decomposition of an inorganic material or a composite material of a metal powder material and an organic material.

[0024]

【Example】

Example 1 A decomposition tank equipped with a valve was filled with 50% of water at pH 7 and charged with glass fiber reinforced plastic. The valve was closed to completely close the decomposition tank, and the pressure was reduced by a vacuum pump to remove air. The pressure is returned to atmospheric pressure while filling the gas. Next, the decomposition bath is immersed in a constant-temperature bath at 330 ° C., and left for 30 minutes in a subcritical state. Thereafter, the decomposition tank is taken out and returned to room temperature. The valve was opened, and the gas phase was collected first, and subjected to gas chromatography-mass spectrometry.

The inside of the decomposition tank is divided into two phases of glass fiber and water / oil, and the glass fiber and water / oil are separated and recovered.

It was confirmed that the recovered liquid phase and gas phase decomposed into several tens of gaseous compounds. Further, the obtained glass fiber did not adsorb excess organic substances, and it was confirmed by elemental analysis that it was a completely purified glass fiber.

Example 2 In the same manner as in Example 1, a decomposition tank with a valve was filled with 5.0% of water, charged with glass fiber reinforced plastic, and the decomposition tank was completely closed.

The decomposition bath is immersed in a constant temperature bath at 330 ° C., and is left immersed in a subcritical state for 30 minutes. Thereafter, the decomposition tank is taken out and returned to room temperature. The valve was opened, and the gas phase was collected first, and subjected to gas chromatography-mass spectrometry.

Glass fiber, water and oily substances separated into two phases inside the decomposition tank were separated and recovered. It was confirmed that the recovered gas phase was decomposed into tens of gaseous compounds. The glass fiber to which the oily substance had adhered was washed with tetrahydrofuran. As a result, no excess organic matter was adsorbed to the obtained glass fiber, and it was confirmed by elemental analysis that the glass fiber was completely purified.

Examples 3 to 6 Glass fiber reinforced plastics were treated in the same procedure as in Example 2 except that the filling rate of water, reaction temperature and treatment time shown in Table 1 were changed.

[0031]

[Table 1]

The third embodiment is in a subcritical state, and the fourth embodiment is different from the fourth embodiment.
~ 6 were processed in a supercritical state. As a result, as in Example 2, it was confirmed that the recovered liquid phase and gas phase decomposed into several tens of compounds. The glass fiber to which the oily substance had adhered was washed with tetrahydrofuran. As a result, no excess organic matter was adsorbed on the obtained glass fiber, and it was confirmed by elemental analysis that the glass fiber was completely purified.

[0033]

【The invention's effect】

(1) Conventionally, waste fiber-reinforced plastics that have been landfilled and incinerated as industrial waste can be efficiently decomposed and recovered. (2) It is socially and legally useful because toxic decomposition products can be collected and purified without discharging them outside the system. (3) It is a process that is safe for the human body and the environment because it can be purified and recovered without crushing and discharging the glass fiber out of the system. (4) Since it can be collected and reused without damaging expensive carbon fibers and the like, it has a great economic effect.

[Brief description of the drawings]

FIG. 1 is a diagram of a fiber-reinforced plastic decomposition / recovery system for carrying out the method of the present invention.

FIG. 2 is a scanning electron micrograph of an unused reinforcing fiber and a processed reinforcing fiber, and FIG. 2- (a) (15.0 kV ×
1.79K) and FIG. 2- (b) (15.0 kV × 5)
0.0) is an unused reinforcing fiber, and FIG. 2- (c) (15.0).
kV × 1.80K) and FIG. 2- (d) (15.0 k
(V × 50.0) is a scanning electron micrograph showing the reinforcing fibers after the treatment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Decomposition layer 2 Water cylinder 3 Water tank 4 High pressure pump 5, 6 Valve 7 Constant temperature bath 8 Heat exchanger 9 Trap

Continued on the front page (72) Inventor Takeshi Sako 1-1 Higashi Tsukuba, Ibaraki Pref., National Institute of Advanced Industrial Science and Technology (72) Inventor Katsuhito Otake 1-1 Higashi 1-1, Tsukuba, Ibaraki Pref. Inside the Technical Research Institute (72) Katsuhiko Ueno 1-1, Higashi, Tsukuba, Ibaraki Pref.Institute of Materials Science and Technology, National Institute of Industrial Science (72) Inventor Shinji Sato 1-1, Higashi 1-1, Tsukuba, Ibaraki Pref. (72) Inventor Shoji Nagaoka 3-11-38 Higashicho, Kumamoto City, Kumamoto Prefecture Inside the Industrial Technology Center of Kumamoto (72) Inventor Masanori Nagata 3-11-38 Higashicho, Kumamoto City, Kumamoto Prefecture Inside the Industrial Technology Center Kumamoto ( 72) Inventor Shohei Nagayama 3-11-38 Higashicho, Kumamoto City, Kumamoto Prefecture Inside the Kumamoto Prefectural Industrial Technology Center (72) Inventor Makoto Uemura 3-11-38 Higashicho, Kumamoto City, Kumamoto Pref. Ryoko Masuda (56) References JP-A-5-31000 (JP, A) JP-A-5-2713 28 (JP, A) WO 95/4796 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 11/10 B29B 17/00 C10G 1/10

Claims (5)

(57) [Claims] 1. A fiber reinforced plastic is charged in a reactor.
And remove the air by reducing the pressure, and then fill in Ar gas.
A method for recovering and reusing fiber from fiber-reinforced plastic, which comprises bringing the fiber-reinforced plastic into contact with and reacting with supercritical water or subcritical water in a reactor at atmospheric pressure, separating and recovering the fiber, and reusing the fiber. . 2. In a reactor, 30 fiber-reinforced plastics are added.
The method for recovering and recycling fibers from a fiber-reinforced plastic according to claim 1, wherein the method is carried out at a reaction temperature of 0 to 500C. 3. The fiber reinforced plastic according to claim 1, wherein the pH of the supercritical water or the subcritical water is adjusted to a neutral range of 4 to 8 to prevent partial hydrolysis of the glass fiber. For fiber recovery and reuse from fiber. 4. An organic polymer component of a fiber reinforced plastic.
A catalyst such as metal bicarbonate to promote the hydrolysis of
4. The method for recovering and recycling fibers from fiber-reinforced plastic according to claim 1, wherein the fibers are treated . 5. A method for refining the surface of separated and recovered fibers.
The method for recovering and reusing fibers from a fiber-reinforced plastic according to claim 1 , characterized in that: