JP2002332378A - Contraction of polystyrene foam and melt of plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for softening and contracting a polystyrene foam, a polyurethane foam, or a plastic by treatment with a liquid. SOLUTION: A polystyrene foam, a polyurethane foam, or a plastic is brought into contact with a liquid prepared by heating an alcohol such as a polyol, especially, a diol or a triol, to 60-180 deg.C to soften and contract it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foamed plastic and a method for softening and reducing plastic.

[0002]

2. Description of the Related Art There are two types of styrene foam reduction methods: a direct heating reduction method and a solvent reduction method. The direct heat reduction method has drawbacks such as generation of styrene monomer due to thermal decomposition, difficulty in uniform reduction and blackening of a part, and complicated equipment, and the solvent reduction method is receiving attention. But,
All conventional solvent reduction methods use petroleum-based solvents and are harmful (for example, even if oil extracted from food is used, those oils are harmful to the human body due to their high concentration)
And has a fatal drawback such as a high risk of ignition explosion. In addition, the only way to reduce the size of foamed polyurethane and soften plastics such as polyethylene is by heating, and it is difficult to recycle due to thermal denaturation.

[0003]

SUMMARY OF THE INVENTION The safety of human body and the environment is high, the flash point is high, the flame resistance is low and there is almost no danger of fire. In addition, foams such as styrene foam and polyurethane foam can be reduced. A novel solvent capable of softening plastics (including rubber-like substances) having a primary transition point of 210 ° C. or less, such as polyethylene, polypropylene, PVC, epoxy, polyvinylidene chloride, and polybutadiene, is found. In the following, softening and shrinking mean collectively meaning that a foam is reduced (including a case where a part is dissolved) and a plastic that is not a foam is softened.

[0004]

SUMMARY OF THE INVENTION The inventors have discovered that warming alcohols shrink foams such as styrofoam. Among alcohols, monohydric alcohols have a low flash point and are highly toxic. Therefore, the inventor has taken the step forward and found that safe diols or triols can be used for about 1
It has been found that heating to 00 to 180 ° C. (maximum) reduces foams such as styrofoam. Also, plastics such as polyethylene can be softened by this method,
By selecting a softening reducing solution, the first transition point 210 ° C.
Up to plastic can be softened. In general, diols and polyols have a high flash point and a low risk of flammable explosion or fire (mostly petroleums of the Fire Service Law Class 4). According to the present invention, the styrofoam and the polyurethane foam are not melted but only reduced. The softened plastic and the reduced styrene are completely incompatible with strong polar solvents such as polyols, so that if the solvent is sufficiently washed out, a plastic free of the solvent or a reduced polystyrene can be obtained. In the case of Styrofoam, about 30
Reduce to one part. The reduction rate can be reduced to 1/50 to 1/100 by applying pressure, and the time can be reduced. The term “softening-reduced liquid” used in the present invention includes a liquid that is solid at ordinary temperature but becomes liquid when heated.

[0005] Among the aliphatic monohydric alcohols, propanol, butanol, higher alcohols and the like are reduced only without dissolving styrene foam even at a very high temperature (these alcohols are reduced at about 60 ° C). next,
The diol refers to a compound having two alcoholic OH groups. The polyol is a compound having three or more OH groups. Diols include glycols and monoacylglycerols, both of which have a reducing power. Glycols include those in which two OH groups are added to an alkylene such as an ethylene group, a propylene group, and a butylene group. Specifically, ethylene glycol and its 2, 3, or tetramer diethylene glycol or triethylene Glycol, tetraethylene glycol and the like; propylene glycol and its dimer and trimer such as dipropylene glycol and tripropylene glycol; and butylene glycol and trimethylene glycol. Among them, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol have high safety to human bodies and are nonflammable.
Ethylene glycol is highly toxic.

In addition, in the present invention, high molecular alkylene glycols, which are polymers of glycols contained in diols and are also monohydric alcohols, also have a contracting power when heated. For example, polyethylene glycol, polypropylene glycol and the like also reduce the foamed polyethylene at about 150 ° C.
However, as the molecular weight of the liquid increases, the safety increases, but the flammability also increases.

[0007] Representative polyols include triols such as glycerin, trimethylolethane, trimethylolpropane, sorbitol and mannitol. These are solids, but when used alone or mixed with another liquid and heated, there is no practical problem, and they may be mixed with other solvents. Since trimethylolpropane has a melting point of 59 ° C., it easily becomes liquid by heating,
Since it has a boiling point of 292 ° C., it does not easily volatilize, and is excellent as a styrene foam volume reducing solvent. These polyols have high human safety, extremely high flash point, and are difficult to burn.

[0008] All the above-mentioned liquids develop a contraction force only when heated, and have no contraction force at room temperature.
At a liquid temperature of approximately 80 ° C., slight bubbles are generated on the surface of the styrene foam, and the bubbles are gradually generated at 100 ° C.
At 110 ° C., the generation of bubbles is accelerated, and the shrinkage occurs when the temperature exceeds 130 ° C .; Further, there is no reason why each of the above liquids is a single product, and it is common to use them as a mixed liquid.

[0009] Electric heating and combustion heating are generally used for heating, but the inventor has found that high-frequency induction heating, microwave heating, and ultrasonic heating are effective. Monohydric alcohols, diols and triols can be warmed by these means. Here, the ultrasonic heating means irradiating an ultrasonic wave of 16,000 Hz or more, but depending on the irradiation time and intensity, heating may be possible even with high-frequency vibration of several thousand Hz.

An example of an apparatus for softening and reducing styrofoam and plastic using the above-mentioned softening and reducing liquid is shown below. As shown in FIG. 1, the softening / reducing tank (4) is divided into upper and lower parts, and a softening / reducing liquid (1) heated through a heater (8) is put in the upper part, and styrofoam and the like are put there. If possible, press down from above with a plate with a bar to reduce the size so that it will sink into the liquid. As a result, pressure is applied and reduction can be achieved efficiently. Next, if the valve A (5) is opened, the upper reduced liquid flows out to the lower waste solvent reservoir (3). The reduced styrene and plastic remain on the net (2), and the water in the right water tank (12) is poured from the reduction tank by opening the valve B (9), and the net is vibrated to reduce the styrene or softening. The softened reduced solution is extracted and washed from the plastic. Next, the net is pulled up to take out styrene or plastic. In the next step, the waste solvent sump liquid is heated (for example, at 150 ° C.) while being sent to the heater (8) (for example, microwave heating) by the pump (6), and is injected from above the softening / reducing tank (4). Next, a piece of styrofoam or plastic is put into the tank. The tube from the heater (8) to the tank, and the tank itself, may be prepared for electrothermal heating (for example, at 60 ° C.) in preparation for winter or the like. It is not necessary to store the softening reducing liquid in the reducing tank, and if a method is used in which the softening reducing liquid is sprayed from above as a shower, the apparatus can be made compact and the tank for storing the liquid can be made small. I can do it.

Next, according to an embodiment of the present invention, the above-mentioned softened and reduced liquid (each of which may be mixed with the reduced liquid to have characteristics) is heated to 100 to 180 ° C. (the temperature must be lower than the boiling point). Then put a piece of styrofoam or plastic or rubber and stir or
The fragments are brought into sufficient contact with the liquid, such as by pushing them into the liquid.
If the temperature is 130 ° C. or higher, bubbles immediately come out of the foam, and the styrene foam shrinks. At this time, if pressure is applied, the reduction can be accelerated. After shrinking,
Scoop it up or move the liquid to another tank,
The reduced polystyrene remaining on the bottom net is washed with water or the like. For cleaning, jet cleaning or ultrasonic cleaning may be performed in addition to rinsing. It is also preferable to mix well with water and extract and remove the reduced liquid. Next, the taken out reduced polystyrene is dried. It should be noted that some monohydric alcohols exhibit a reducing force from about 50 to 60 ° C. In this case, in order to reduce the flammability, for example, water or the like may be mixed with the volume reducing liquid as a noncombustible agent. Since glycols and polyols gradually oxidize, a phenolic antioxidant such as BHT or a phosphorus-based or ionic antioxidant may be mixed to prevent oxidation.

When dissolving plastic, rubber, etc., select a solvent having a boiling point equal to or higher than the primary transition point of plastic.
Put the solvent in the tank and put the plastic into it to dissolve it. The liquid temperature is always kept above the first transition point. In the case of foamed polyurethane, if it is softened by immersing it in a heated reducing liquid for several minutes, and then compressed by applying pressure, a tenth of the reduced body can be obtained. Note that most of the softening reducing liquid absorbs moisture, weakens the softening reducing power and requires a higher temperature. Therefore, a dehydrating agent such as anhydrous sodium sulfate is touched when not used.

[0013] Among the reduced liquids, five liquids of tripropylene glycol, tetraethylene glycol, dipropylene glycol, glycerin, and trimethylolpropane (there are liquid ones) have high safety, and are more than the flash point. Styrofoam can be rapidly reduced even at a temperature of several tens of degrees or less.

The softening reduced liquid does not need to be used alone, and may be used in combination in consideration of flammability, fluidity, boiling point, difficulty of heating, and the like.

[0015]

Example 1 100 ml of propylene glycol was microwave-heated in a microwave oven (500 W) for 2 minutes. At that time, the liquid temperature was 120 ° C. A styrofoam fragment was put there, and pushed into the liquid with a stick.

[0016]

Example 2 The mixture was heated in a microwave oven using 100 ml of glycerol to adjust the solution temperature to 125 to 150 ° C., and reduced in the same manner as in Example 1.

[0017]

Example 3 100 ml of dipropylene glycol was heated in a microwave for 1 minute to 130 ° C.
A small piece of styrofoam was put in and reduced.

[0018]

Example 4 Polypropylene glycol (molecular weight 30)
0) Heat 100ml in microwave oven to 130 ℃,
A small piece of styrofoam was put there and reduced.

[0019]

Example 5 Polyethylene glycol (molecular weight: 400)
100 ml was heated in a microwave oven to 170 ° C., and a small piece of styrofoam was put therein and reduced instantaneously.

[0020]

Example 6 Polypropylene glycol (molecular weight: 400
0) 100 ml was heated in a microwave oven for 2 minutes to 185 ° C., and a small piece of styrofoam was put therein and reduced instantaneously. Also, 10 g of a polyethylene block was softened.

[0021]

Example 7 Soft foamed polyurethane was placed in 170 ° C. diethylene glycol in a container and left to soften for 5 minutes. Next, the liquid was transferred to another container and pressed from above to reduce the flexible urethane foam. In addition, 10 g of polypropylene was softened.

[0022]

Example 8 To 225 g of trimethylolethane powder was added 30 g of triethylene glycol, and the mixture was heated to a liquid by heating on a hot plate to 130 ° C. A piece of styrofoam was put into this liquid and reduced.

[0023]

Example 9 Isopropyl alcohol was heated to 70 ° C., and styrene foam was added to reduce the size.

[0024]

Example 10 Approximately 100 ml of each of propylene glycol and dipropylene glycol was placed in an ultrasonic washer US100 (45 kHz) manufactured by GL Sciences, and irradiated with ultrasonic waves to adjust the temperature of the irradiated part to 110 ° C.
It was reduced at the center of the irradiated part.

[0025]

Example 11 Triethylene glycol was heated to 140 ° C., and styrene foam was reduced to 1/30 in 10 seconds.

[Brief description of the drawings]

FIG. 1 is a styrofoam and plastic softening reduction device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Softening reduced liquid 2 Net 3 Waste solvent sump 4 Reduction tank 5 Valve A 6 Pump A 7 Valve C 8 Heater 9 Valve B 10 Pump B 11 Piping 12 Water tank 13 Water

Claims (10)

[Claims] 1. A method for heating an aliphatic monohydric alcohol, diol or polyol or a mixture thereof to soften and reduce styrofoam, polyurethane foam and plastic. 2. The method of claim 1, wherein the diol is a glycol or a monoacylglycerol. 3. The foamed polystyrene according to claim 2, wherein the glycol is an alkylene glycol or a polymer thereof.
Polyurethane foam, plastic softening reduction method. 4. The method according to claim 3, wherein the alkylene glycol is ethylene glycol or a polymer thereof. 5. The method according to claim 3, wherein the alkylene glycol is propylene glycol or a polymer thereof. 6. The method according to claim 1, wherein the polyol is a triol.
Styrofoam, polyurethane foam, plastic softening reduction method described. 7. The styrofoam according to claim 6, wherein the triol is glycerin or trimethylolpropane.
Polyurethane foam, plastic softening reduction method. 8. An apparatus for reducing styrene foam, polyurethane foam, and plastic softening comprising a heater, a styrene foam, polyurethane foam, and a reduction furnace according to the plastic softening reduction method according to claim 1 and a sorter. 9. The reduction softening apparatus according to claim 8, wherein the reduction furnace employs a system in which the heated solvent is showered. 10. The softening / reducing apparatus according to claim 8, wherein the heating method of the heater is any one of induction heating, microwave heating, and ultrasonic heating or a mixture.