JPH0841238A - Resin foamed material and decomposition - Google Patents

Abstract

PURPOSE:To obtain a resin foamed material containing a foaming agent consisting of a hydrocarbon chloride in bubbles, also containing a chlorine- trapping agent, excellent in heat insulation properties, prevented from production of toxic chlorine gas when burned for waste treatment and useful for a refrigerator, freezer, etc. CONSTITUTION:This is a resin foamed material made of a rigid polyurethane foam, etc. The foamed material contains (A) a foaming agent consisting of a hydrocarbon chloride, e.g. propyl chloride or butyl chloride in bubbles and (B) a chlorine-trapping agent such as a metal hydrogencarbonate, e.g. sodium hydrogencarbonate, a metal oxide, e.g. calcium oxide, a metal hydroxide, e.g. calcium hydroxide, a metal carbonate, e.g. calcium carbonate, a basic metal salt, e.g. a tribasic metal salt or a carboxylic acid salt of a metal, e.g. Pb, Ba, Zn, Ca and Sn. Further, preferably, the foaming agent contains a hydrocarbon fluoride.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin foam used in refrigerators, freezers and the like and a method for decomposing the same.

[0002]

2. Description of the Related Art Gas generated during the disposal of plastics pollutes the atmosphere and causes pollution problems such as photochemical smog. In particular, foamed plastics have a much higher ratio of gas used as a foaming agent than other plastic products, and thus need to be treated so as not to emit harmful gas. Among foamed plastics, CFCs have been used as a foaming agent for heat insulating materials. The reason is that CFCs have the characteristics of low thermal conductivity, chemical stability, and low toxicity. However, in recent years, fluorocarbons containing chlorine, in particular, are said to make a great contribution to the depletion of the ozone layer.
It has been decided to abolish specific CFCs in the year, and to abolish designated CFCs in 2020. As an alternative technique, there is a technique of using hydrocarbons, carbon dioxide gas, or the like as a foaming agent.

Further, in recent years, effective utilization of global resources has become a serious problem, and various recycling methods for resin products have been developed. As one of the methods, a method has been developed in which the resin is decomposed by heat or a catalyst to be in a state close to the raw material and recycled. Urethane foam is particularly advantageous for such a method, and uses other than foamed plastic have been developed, such as using a decomposition product mixed with a raw material for use or as an adhesive. There are two methods for decomposing polyurethane: solvolysis in a suitable solvent and heating at high temperature using steam, both of which require considerably high pressure and require a long time, resulting in product separation. There are drawbacks such as being troublesome.

[0004]

DISCLOSURE OF THE INVENTION Regarding the disposal of the above-mentioned foamed plastic having chlorine-containing compounds in the air bubbles, a large amount of chlorine-containing gas is generated during crushing, and therefore, in order to treat the gas, an incinerator is required. In addition to the above, there is a problem that a large gas treatment facility for foamed plastic is required. Further, it is very difficult for the heat insulating material by the alternative technology for the total abolition of CFCs to maintain the same heat insulation performance as that using a specific CFC. In addition, when recycling foamed plastic considering the use of resources, special processing equipment is required, and since the density is small and the volume is large, costs such as transportation cost from collection to processing site, processing cost, etc. per resin weight There was also the problem that it would become very large.

It is an object of the present invention to provide a resin foam having excellent heat insulation properties, which uses a novel foaming agent having a low thermal conductivity and does not discharge harmful gas at the time of disposal. Another object of the present invention is to provide a method which is very effective for on-site treatment or small-scale treatment and which is capable of recycling urethane foam raw materials without discharging harmful gas.

[0006]

The resin foam of the present invention comprises:
In addition to containing a blowing agent consisting of chlorinated hydrocarbons in the bubbles,
It contains a chlorine scavenger. Here, as the chlorinated hydrocarbon, at least one selected from the group consisting of propyl chloride and butyl chloride is preferably used.
And propyl chloride is 1-chloropropane and 2
Preferably, it is at least one selected from the group consisting of -chloropropane, and butyl chloride is at least one selected from the group consisting of 1-chlorobutane, 2-chlorobutane, tertiary butyl chloride and isobutyl chloride. The resin foam is preferably rigid polyurethane foam.

The chlorine scavenger is preferably at least one selected from the group consisting of metal hydrogen carbonate, metal hydroxide, metal oxide, metal carbonate, basic metal salt and metal carboxylate. Sodium hydrogen carbonate is preferable as the metal hydride, calcium hydroxide as the metal hydride, calcium oxide as the metal oxide, and calcium carbonate as the metal carbonate. As the basic metal salt, there are monobasic, dibasic and tribasic metal salts, among which the tribasic metal salt is preferred. The metal carboxylate is preferably a metal carboxylate selected from the group consisting of lead, barium, zinc, calcium and tin.

The present invention further provides a resin foam containing fluorocarbon as a foaming agent. Fluorinated hydrocarbons include 1,1,2,2,3-pentafluoropropane,
It is preferably at least one of 1,1,1,4,4,4-hexafluorobutane.

The method for decomposing a resin foam of the present invention is a resin foam made of a urethane foam containing a foaming agent made of chlorinated hydrocarbon in bubbles and a chlorine scavenger made of sodium hydrogen carbonate and calcium hydroxide. To
By adding water and heating it to 270 ° C. or higher, it is hydrolyzed to produce a polyurethane raw material.

[0010]

In the resin foam containing the chlorine scavenger in the bubbles and containing the chlorine scavenger, the foaming agent having a low thermal conductivity can form a foamed heat insulator having a high heat insulating property. Furthermore, by containing a chlorine scavenger in the foam, chlorine-based harmful gas is not discharged to the outside at the time of disposal. Chlorinated hydrocarbon used as a foaming agent in the present invention is a hydrocarbon in which one of hydrogen atoms is replaced by a chlorine atom, and shows low thermal conductivity due to the contribution of a chlorine atom.
It has much lower thermal conductivity than hydrocarbons of the same molecular structure. The blowing agent preferably has a boiling point of 70 ° C. or lower, and propyl chloride and butyl chloride are suitable. 1-chloropropane and 2-chloropropane are suitable as propyl chloride, and 1-chlorobutane, 2-chlorobutane, tert-butyl chloride and isobutyl chloride are suitable as blowing agents for butyl chloride, respectively. Chlorinated hydrocarbons containing two or more chlorine atoms in the molecule generally have high boiling points,
Since many of them are highly toxic, they are not suitable as foaming agents.

The chlorine scavenger quickly absorbs a chlorine-containing toxic gas generated when the chlorinated hydrocarbon as a foaming agent decomposes,
It functions to capture by adsorption or chemical reaction. Since it acts at the time of disposal, it is preferably a solid inorganic substance that is contained in the resin and acts at the same time as pulverization.
The reactions of sodium hydrogen carbonate, calcium hydroxide, calcium oxide and calcium carbonate with hydrogen chloride gas are shown in formulas (1), (2), (3) and (4), respectively.

[0012]

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The basic metal salt has a metal oxide component in the metal salt, and this metal oxide component captures chlorine by the reaction represented by the formula (5). Further, the metal carboxylate captures chlorine by the reaction represented by the formula (6).

[0014]

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Since chlorine gas (Cl ₂ ) is similar in these reactions, both chlorine gas and hydrogen chloride gas produced by decomposition will be described as chlorine gas. Fluorinated hydrocarbons added at the same time as the blowing agent are preferably 1,1,2,2,3-pentafluoropropane and 1,1,1,4,4,4-hexafluorobutane, which are chlorinated hydrocarbons as the blowing agent. Since hydrocarbons are weakly flammable, by mixing these fluorohydrocarbons, the explosive limit of the foaming agent disappears, and the foam can also be made flame-retardant.

At the time of disposal, the resin foam of the present invention is hydrolyzed by adding water and heating it to 270 ° C. or higher.
The polyurethane raw material can be recovered. This method of decomposing a resin foam allows the sodium hydrogen carbonate and calcium hydroxide to capture chlorine gas of chlorinated hydrocarbons generated at the time of disposal by the above-mentioned action, and at the same time, to add sodium hydroxide by adding water and heating at 270 ° C. or more. It is produced, and further, by the action of this sodium hydroxide, the polyurethane resin is decomposed to produce a decomposed product. The reaction mechanism is shown below. Sodium hydrogen carbonate dissolves in water, 27
When heated at 0 to 300 ° C., sodium carbonate is produced as represented by the formula (7). The generated sodium carbonate reacts with calcium hydroxide mixed at the same time to generate sodium hydroxide, as shown in formula (8).

[0017]

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The sodium hydroxide thus produced acts on the decomposition of urethane bonds in the heated state. Therefore, sodium hydrogen carbonate and calcium hydroxide can be used as chlorine scavengers and can also act on urethane hydrolysis to obtain a resin decomposition product (mainly composed of a polyol composition and a urea binding composition). It should be noted that sodium hydrogen carbonate and calcium hydroxide are preferably added in excess of the amount that acts as a chlorine scavenger.

[0019]

EXAMPLES The resin component of the resin foam used in the present invention includes thermoplastic resins such as polystyrene, polyethylene, polypropylene and vinyl chloride resin, as well as thermosetting resins such as polyurethane resin, urea resin and phenol resin. is there. Among them, the polyurethane resin, after mixing the foaming agent in advance in the raw material polyol premix,
When mixed with an isocyanate component, it foams due to the heat of polymerization reaction to form a resin foam. Therefore, there is an advantage that the foam can be formed on the spot by a simple method and the foam can be packed into the detailed structure. Therefore, it is a resin that is very effective for applications requiring high heat insulating properties such as a heat insulating material for refrigerators. In the present invention, this polyurethane resin is most suitable.

The propyl chloride used in the blowing agent of the present invention is 1-chloropropane (molecular weight 78.5, boiling point 34.
8 ℃, 2-chloropropane (molecular weight 78.5, boiling point 4
7.2 ° C.), but butyl chloride is 1-chlorobutane (molecular weight 92.6, boiling point 78.5 ° C.), 2-chlorobutane (molecular weight 92.6, boiling point 68 ° C.), tertiary butyl chloride (molecular weight 92.6, Boiling point 49.5 ° C), Isobutyl chloride (molecular weight 92.6, boiling point 68.2-68.3 ° C)
Are desirable respectively. These have a relatively low foaming temperature,
Since it foams with low energy, the physical properties of the resin foam can be easily manipulated. Furthermore, by containing chlorine, the compatibility with the urethane resin raw material becomes better than that of a general nonpolar hydrocarbon, and the foamability is improved, which is preferable. In addition, since chlorine is contained in the molecule, the molecular weight is large and the gas thermal conductivity is low as compared with hydrocarbons having the same skeleton, and thus it is preferable as a foaming agent for a heat insulating resin foam because the heat insulating property is improved. In general, chlorinated hydrocarbons are harmful, but these chlorinated hydrocarbons have only one chlorine atom in the molecule, and the chlorine gas released from polychlorinated hydrocarbons by the decomposition at the time of disposal. The ratio is low, and the probability that toxic chlorine gas is released to the outside is extremely low due to rapid absorption by the capture agent.

The chlorine scavenger used in the present invention captures chlorine gas, which is generated by heating the foamed resin body at the time of disposal, by converting it to a metal chloride. Preferred chlorine scavengers are sodium bicarbonate, calcium hydroxide, calcium oxide, calcium carbonate, tribasic metal salts, and lead,
It is a carboxylate of a metal of barium, zinc, calcium or tin. As the basic metal salt, tribasic lead sulfate _{(3PbO · PbSO 4 · H 2} O), tribasic maleic lead _{(3PbO · Pb (C 4 H} 2 O 4) H 2 O) tribasic such as Metal salts are most desirable, but dibasic lead phosphite (2PbO · PbHPO ₃ 1 / 2H ₂ O), lead white (2P
bCO ₃ · Pb (OH) ₂ ), dibasic lead phthalate (2P
_{bO · Pb (C 8 H 4} O 4)) dibasic metal salts such as, and, basic lead silicate _{(PbO · H 2 O · 2PbSiO} 3)
A monobasic metal salt represented by is also used. Examples of the metal carboxylate include calcium stearate (Ca (C
₁₇ H ₃₅ COO) ₂ ), calcium laurate (Ca (C
₁₁ H ₂₃ COO) ₂ ), calcium ricinoleate (Ca
(C ₁₇ H ₃₂ (OH) COO) ₂ ), zinc stearate (Zn (C ₁₇ H ₃₅ COO) ₂ ), lead stearate (Zn
(C ₁₇ H ₃₅ COO) ₂ ) and tin stearate (Sn (C ₁₇
H ₃₅ COO) _2), barium stearate (Ba (C ₁₇
H ₃₅ COO) ₂ ) is preferred.

In order to prevent decomposition due to water, it is most preferable to coat the above-mentioned inorganic powder with a thermoplastic resin to improve the reaction yield. Further, in order to make the dispersion in the resin uniform, it is desirable to add it as micron-order fine particles, and in order to improve the kneading with the resin, add it to a resin with a low viscosity in the heated state and knead it. It is desirable to do. In particular, the urethane resin is the most suitable resin material for uniformly dispersing the inorganic powder, since it can be added to the premix of the low-viscosity raw material in advance. Further, since these inorganic powders serve as nuclei for cell formation, the cell diameter can be finely and uniformly foamed, and thereby the physical properties of the foamed product can be improved.

In addition to the chlorinated hydrocarbon used in the present invention, it is preferable to add a foaming agent effective for improving the flame retardancy of the foam and reducing the thermal conductivity. Among them, flame retardancy can be imparted by adding the following highly fluorinated hydrocarbons having a fluorination ratio of 50% or more. These highly fluorinated hydrocarbons have a relatively low boiling point that does not cause any problems during foaming, and are therefore preferable for improving the foamability of the chlorinated hydrocarbon foaming agent. Highly fluorinated hydrocarbons are 1, 1, 2,
2,3-Pentafluoropropane (Molecular weight 134.0
6, boiling point 26 ° C), 1,1,1,4,4,4-hexafluorobutane (molecular weight 166.07, boiling point 24.6 ° C)
Etc. are suitable. Also, these fluorohydrocarbons
Since it has a large molecular weight and generally exhibits low thermal conductivity, it is a very effective material for improving the heat insulating property of the foam.

Next, in the method for decomposing a resin foam, when the urethane resin foam is discarded and heated, the additives sodium hydrogen carbonate and calcium hydroxide only have a chlorine gas-trapping effect, but they are not absorbed by water. It has the characteristic of dissolving,
When the urethane raw material is hydrolyzed and recycled, the function of acting as a catalyst for resin decomposition and the capture of chlorine gas generated by thermal decomposition are simultaneously performed. In the hydrolysis reaction of the present invention, a polyol composition can be obtained in a high yield as a urethane decomposition product also by mixing primary and secondary low molecular weight alcohols such as ethylene glycol. Next, the present invention will be described in more detail with reference to specific examples.

[Example 1] As a raw material of a polyurethane resin, 100 parts by weight of an aromatic amine-based polyether polyol having a hydroxyl value of 449 mgKOH / g (hereinafter simply referred to as "part") and a foam stabilizer (comprising a silicone surfactant) ( 3 parts of TY19 from Takeda Pharmaceutical Co., Ltd., 2 parts of an amine-based catalyst (Kaorizer No. 1 from Kao Co., Ltd.), and 23 parts of 1-chloropropane as a foaming agent were mixed to form a polyol premix. . Further, 20 parts of sodium hydrogen carbonate was added to this premix to form a solid dispersion premix. On the other hand, the isocyanate component has an amine equivalent of 1
70 of which was mixed with the premix at a ratio of 165 parts to 100 parts of polyol. The polyol premix component and the isocyanate component thus prepared are mixed at a predetermined ratio, and mixed and stirred by a high-pressure foaming machine,
A space formed by an outer box 1 and an inner box 2 as shown in FIG. 1 was filled and foamed to obtain a polyurethane foam heat insulating foam 3.

Comparative Example 1 A polyurethane foam was obtained in the same manner as in Example 1 except that sodium hydrogen carbonate was not contained. Comparative Example 2 A polyurethane foam was formed in the same manner as in Example 1 except that cyclopentane was used as the blowing agent instead of 1-chloropropane.

The thermal conductivity, compressive strength and dimensional stability of the heat insulating foams obtained in Example 1 and Comparative Examples 1 and 2 were measured. Compared with the polyurethane foam of Comparative Example 2, the polyurethane foam obtained in Example 1 had a thermal conductivity of 1.4 times, because 1-chloropropane as a foaming agent has lower thermal conductivity than cyclopentane. . In addition, the cell structure was made finer than that of the 1-chloropropane foamed polyurethane of Comparative Example 1 containing no sodium hydrogencarbonate by 150 μm.
Since it is about m, the heat insulating property is improved 1.2 times.
Further, regarding the physical properties of the formed polyurethane foam, the density was increased by 10% due to the influence of the inorganic solid, but the compressibility and the dimensional stability were improved as compared with Comparative Example 2. This is considered to be the effect of adding sodium hydrogen carbonate to the resin. When an experiment was conducted in which the polyurethane foam obtained in Example 1 was crushed and burned in a combustion furnace, almost no gas component containing chlorine was detected by the gas analysis generated from this combustion furnace. It was found that about 90% or more of chlorine gas generated from the urethane foam to which sodium hydrogen carbonate was not added was trapped by reacting with sodium hydrogen carbonate. After burning, the ash was dispersed in water, solids were filtered off and the filtrate was dried, revealing crystals of sodium chloride.

When 1 part of water was added in advance in foaming 1-chloropropane expanded polyurethane, the thermal conductivity was further reduced, and the heat insulation performance was about 1.3 times that of cyclopentane expanded foam. It was However, when the chlorine gas capturing ability was tested, it was found that only about 60% was captured. This seems to be due to the loss of the activity of the scavenger sodium hydrogen carbonate due to the addition of water. Therefore, a sodium hydrogencarbonate powder coated with a polystyrene resin was prepared, mixed into a premix, and water was added in advance in the same manner as described above to form a foamed foam. When this foam was crushed and tested for its chlorine capturing ability, it was found that chlorine gas was trapped in a high yield of 95% or more. The physical properties of this foam were the same as those of the conventional one, and no particular bad point was observed.

Example 2 In Example 1, instead of 1-chloropropane, tertiary butyl chloride and 1,
The molar ratio of 1,1,4,4,4-hexafluorobutane was 2
38 parts of the foaming agent mixed in a ratio of 1 was used to form a polyurethane foam in which calcium carbonate was solid-dispersed in place of sodium hydrogen carbonate as a chlorine scavenger. The thermal conductivity of the foam is about 1.35 times that of the cyclopentane foamed foam of Comparative Example 2, and the physical properties of the foam are almost the same as those of the urethane foam of Example 1, which is comparable to the conventional one. There wasn't. It was found that the foam burning time was delayed due to the incorporation of 1,1,1,4,4,4-hexafluorobutane, and that the cyclopentane foam of Comparative Example 2 was flame retarded. The decomposed chlorine gas generated in the combustion furnace was captured by calcium carbonate in an amount of 85% or more. When foam ash was dissolved in water and the filtrate was dried in the same manner as in Example 1, the obtained crystals were deliquescent and were considered to be calcium chloride.

Example 3 A urethane foam was formed in the same manner as in Example 1 except that 12 parts of sodium hydrogen carbonate and 12 parts of calcium hydroxide were used as chlorine scavengers. This urethane foam has 1.3 times the heat insulating property as compared with the cyclopentane foam of Comparative Example 2 and has a compressive strength of about 1.5% lower, but other foam physical properties are similar to those of the conventional foam. Met. Urethane foam was crushed and heated at 270 ° C for several tens of minutes, about 500 g of water was further added, and the same heating was performed and left for 3 hours at 270 ° C, the foam was decomposed and changed into a highly viscous solution state. did. Further, 100 g of water was added and the mixture was allowed to stand for 1 hour. However, since the state of the decomposed product of the foam did not change, it was confirmed that the hydrolysis of the foam was almost completed. As a result of analyzing the generated gas,
Almost no harmful chlorine gas was detected, and it was found that 90% or more of chlorine gas was captured. Decomposition products were added to the polyol composition after solid filtration and dehydration with excess water.
When urethane foam was made as a raw material mixed with a relatively small amount, a urethane foam having substantially the same foam characteristics as the conventional one was formed.

[0031]

As described above, according to the present invention, a resin foam having a high heat insulating property and an improved foaming property can be obtained. Further, this resin foam can capture the toxic chlorine gas generated at the time of waste combustion and prevent the toxic gas from being discharged to the outside. Further, according to the method of the present invention, it is possible to hydrolyze the resin foam and recover the polyurethane raw material.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of a heat insulating box for a refrigerator filled with a rigid polyurethane foam as a resin foam of the present invention.

[Explanation of symbols]

 1 Outer box 2 Inner box 3 Rigid polyurethane foam

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C08L 75:04

Claims (6)

[Claims] 1. A resin foam comprising a foaming agent made of chlorinated hydrocarbon in bubbles and a chlorine scavenger. 2. The resin foam according to claim 1, wherein the chlorinated hydrocarbon is at least one selected from the group consisting of propyl chloride and butyl chloride, and the resin foam is a rigid polyurethane foam. 3. The chlorine scavenger is at least one selected from the group consisting of metal hydrogen carbonate, metal hydroxide, metal oxide, metal carbonate, basic metal salt and metal carboxylate. 1. The resin foam according to 1. 4. The resin foam according to claim 3, wherein the metal carboxylate is a metal carboxylate selected from the group consisting of lead, barium, zinc, calcium and tin. 5. The foaming agent contains fluorohydrocarbon.
The resin foam described. 6. Water is added to a resin foam made of urethane foam containing a chlorine scavenger made of chlorinated hydrocarbon in a bubble and containing chlorine scavenger made of sodium hydrogen carbonate and calcium hydroxide at 270 ° C. or higher. A method for decomposing a resin foam, characterized in that it is hydrolyzed to produce a polyurethane raw material by heating to a temperature of 1.