JP2001098107A - Method for decomposition treatment of thermosetting resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for the high-speed and mass-decomposition treatment of thermosetting resins contained in large quantities in industrial wastes and general wastes so as to recycle them. SOLUTION: This method comprises the hydrolysis and/or pyrolysis of thermosetting resins in supercritical or subcritical water as solvent into low- to medium-molecular weight compounds containing >=50 wt.% of mono- to binuclear phenolic compounds; wherein a salt made from an alkali (alkaline earth) metal and a phenolic compound is added as catalyst to the system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a thermosetting resin which has not been able to be recycled until now, although it is contained in a large amount in industrial waste or general waste which is disposed in large quantities from factories and the like. The present invention relates to a method of recovering and reusing as a low to medium molecular compound containing 50 wt% or more of a reusable 1-2 dinuclear phenol compound which is decomposed in a large amount at a high speed.

[0002]

2. Description of the Related Art Among plastics, thermosetting resins are:
Because of its excellent electrical insulation, heat resistance and mechanical strength, it is widely used as a material for electric / electronic parts, automobile parts and the like. However, thermosetting resin, once cured,
Since it does not soften and melt by heat and does not dissolve in a solvent, it is technically difficult to regenerate the cured product as a plastic raw material.

[0003] In recent years, a method of hydrolyzing a thermosetting resin using water in a supercritical state or a subcritical state to selectively recover useful compounds has been studied. If the method disclosed in the publication is used, like an epoxy resin, an ether bond in the structure,
An ester bond, a thermosetting resin having an acid amide bond,
Without adding acid catalyst or alkali catalyst, 400
Under conditions of 10 ° C., 37 MPa, and about 10 minutes, it is possible to completely decompose the compound until it is completely soluble in tetrahydrofuran (THF). However, the phenol resin is very hard to decompose even in supercritical water, and decomposes only to about 20 wt% in THF under the conditions of 400 ° C., 37 MPa, and 10 minutes.

On the other hand, Summers reports that novolak can be recovered from a cured phenolic resin by adding an excess amount of an alkali catalyst and alkali hydrolysis.
(RM. Summers: j. Polym. Sci., Poym. Chem. Ed., 16, 1669
(1978)) The novolak produced by this method forms a salt with an alkali catalyst added because it has a phenolic hydroxyl group, and is recovered as an alkali salt of novolak. In order to separate, purify, and reuse free novolak from the alkali salt of novolak, it is necessary to perform a neutralization treatment with a stronger acid (for example, hydrochloric acid, sulfuric acid, acetic acid, or carbonic acid) than novolak. Further, the alkali added as a catalyst by the neutralization treatment becomes a salt, so that it cannot be reused as an alkali catalyst as it is, but must be treated as waste. Due to such problems in the separation and purification steps, the decomposition treatment by alkali hydrolysis is hardly a useful method.

As described above, although it is widely desired to efficiently decompose a thermosetting resin in a short period of time and recover, separate, purify, and reuse it as a useful low to medium molecular compound, it has been widely realized. Not done.

[0006]

SUMMARY OF THE INVENTION The present invention has been made as a result of various studies to solve the problem that recycling of thermosetting resin is extremely difficult. Its main purpose is to rapidly produce large quantities of thermosetting resins that have not been able to be recycled yet are contained in large amounts in industrial waste and general waste discharged from factories and the like. It provides a method of disassembling and reusing.

[0007]

According to the present invention, a thermosetting resin is hydrolyzed and / or supercritical water or subcritical water is used as a solvent.
Or, by thermal decomposition, 5 to 1 core dinuclear phenol compounds
A thermosetting resin characterized by adding a salt composed of an alkali metal and a phenolic compound or a salt composed of an alkaline earth metal and a phenolic compound as a catalyst when decomposing to low to medium molecular compounds containing 0 wt% or more; A decomposition treatment method, characterized in that the salt composed of an alkali metal and a phenol compound or the salt composed of an alkaline earth metal and a phenol compound used above is recovered, separated, and reused in the decomposition treatment step. This is a method for decomposing a thermosetting resin. The recovered and separated salt of an alkali metal and a phenol compound or the salt of an alkaline earth metal and a phenol compound may be further purified and reused.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The thermosetting resin decomposed by the method of the present invention includes a cured resin, an uncured resin, and a varnish containing a resin. Also, in addition to a single thermosetting resin, inorganic materials such as silica fine particles and glass fibers, molding materials or molded products containing organic fillers such as wood powder, inorganic materials such as glass cloth, paper, etc. , Such as a laminated board using an organic base material such as cloth, a metal-clad laminate obtained by laminating a metal foil such as a copper foil thereto, and a printed circuit board obtained by processing a copper-clad laminate or the like. It shall include thermosetting resin products. The type of the thermosetting resin is not particularly limited, but the present invention can be particularly effectively applied to a phenol resin, an epoxy resin, and a phenol-modified melamine resin.

The mononuclear phenol compounds which can be decomposed and recovered from the thermosetting resin in the present invention include mononuclear phenols such as phenol, cresols and xylenols, dihydroxydiphenylmethane, and 2,2-bishydroxyphenylpropane. And the like, but are not limited to the above-mentioned phenol compounds.

The salt composed of an alkali metal and a phenol compound used in the present invention includes lithium, sodium, potassium, rubidium or cesium as the alkali metal and phenol, cresols, xylenols and the like as the phenol compound. It is formed from a core phenol or a binuclear phenol phenol compound such as dihydroxydiphenylmethane and 2,2-bishydroxyphenylpropane. For example, lithium phenoxide, sodium phenoxide, potassium phenoxide and the like can be mentioned, and sodium phenoxide and potassium phenoxide are preferable from the viewpoint of cost and effect as a catalyst.

The salt composed of an alkaline earth metal and a phenol compound used in the present invention is, as an alkaline earth metal,
Beryllium, magnesium, calcium, strontium or barium and the like, and phenolic compounds such as phenols, cresols, mononuclear phenols such as xylenol, or dihydroxydiphenylmethane, 2,2
And a binuclear phenol such as bishydroxyphenylpropane. For example, calcium phenoxide, magnesium phenoxide, barium phenoxide and the like can be mentioned, but calcium phenoxide and magnesium phenoxide are preferable in terms of cost and effect as a catalyst.

These salts composed of an alkali metal and a phenol compound or salts composed of an alkaline earth metal and a phenol compound are used alone or in the form of a mixture, and do not need to be of high purity. In addition, after these salts are used as a catalyst in the decomposition treatment step, they can be separated and recovered from the recovered liquid after the decomposition reaction by an evaporation operation or the like, and if necessary, purified and used again as a catalyst. Good.

The proportion of the salt composed of an alkali metal and a phenol compound or the salt composed of an alkaline earth metal and a phenol compound added to supercritical water or subcritical water is 0.1 parts by weight with respect to 100 parts by weight of water. -100 parts by weight, preferably 5 to 50 parts by weight.

The decomposition treatment method of the present invention is carried out under the conditions of high temperature and high pressure.
The temperature and pressure may be adjusted to supercritical or subcritical conditions within the range of Ｍ60 Mpa.
The temperature and pressure may be set at a temperature of 60 to 500 ° C. and a pressure of 20 to 50 MPa. The reaction time can be adjusted in the range of 1 to 60 minutes, but usually the decomposition treatment is completed in 3 to 30 minutes. The proportion of water used is in the range of 1 to 20 parts by weight, preferably 2 to 1 part by weight, per 1 part by weight of the thermosetting resin.
The range is 0 parts by weight.

[0015] The size of the thermosetting resin or the thermosetting resin product to be subjected to the decomposition treatment is not particularly limited, but is set in advance so that the decomposition reaction proceeds in a shorter time. It is preferable to pulverize to about 10 mm.

In the present invention, when a thermosetting resin is hydrolyzed and / or thermally decomposed using supercritical water or subcritical water as a reaction solvent, a salt or an alkaline earth metal comprising an alkali metal and a phenol compound is used as a catalyst. By adding a salt composed of a phenol compound, the thermosetting resin, which was particularly difficult to decompose, can be easily decomposed and recovered as a low to medium molecular compound containing 50% by weight or more of a 1- or 2-nuclear phenol compound. can do. Moreover, since the 1- or 2-nuclear phenol compound obtained in the present invention can be recovered as a free phenol compound, it can be separated and purified without performing a neutralization treatment.

[0017]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited thereto.

Example 1 Decomposition of a cured phenolic resin As a thermosetting resin, 15 parts by weight of hexamethylenetetramine was mixed with 100 parts by weight of a phenolic resin.
A phenol resin cured product which was subjected to pressure molding at 50 ° C. for 15 minutes and further subjected to heat treatment at 180 ° C. for 4 hours was used. Small batch type reactor (Internal volume 5cm ³ , Hasteroy
C-276) was charged with 0.25 g of the cured phenolic resin, 1.8 g of water, and 0.25 g of potassium phenoxide as a catalyst pulverized to a particle size of 0.5 to 1.0 mm, and the inside was replaced with argon. Enclosed. The reactor was put into a fluidized sand bath and rapidly heated to 400 ° C. to raise the internal pressure of the reactor to 30 MPa, thereby bringing the reactor to a high-temperature and high-pressure state. After holding at 400 ° C and 30 MPa for 10 minutes,
The reactor was cooled with an air gun and returned to normal temperature and normal pressure. The recovered solution after the decomposition reaction was filtered through a 1.0 μm filter, and the filtrate was used as a water-soluble component. The water-insoluble matter remaining in the filter after the filtration was dissolved in tetrahydrofuran (hereinafter abbreviated as THF), and then filtered through a 1.0 μm filter to obtain a filtrate as a THF-soluble matter. The THF-insoluble residue remaining on the filter was dried at 100 ° C. for 12 hours and then weighed. As a result, about 85 w
The t% was decomposed into a water-soluble component and a THF-soluble component. The water-soluble matter and the THF-soluble matter were analyzed by gas chromatography (detector FID) (hereinafter abbreviated as GC-FID). It was confirmed that it could be collected. The main breakdown of the amount recovered is that phenol is 38 wt% and o-cresol is 23 w%.
t%, 26 wt% of p-cresol, and 13 wt% of others (such as xylenol).

Example 2 Decomposition of Cured Phenolic Resin A decomposition reaction was carried out in the same manner as in Example 1 except that the reaction temperature was set to 440 ° C.
As a result, about 90 wt% of the phenol resin cured product was decomposed into a water-soluble component and a THF-soluble component. Analysis of the water-soluble component and the THF-soluble component by GC-FID confirmed that about 60% by weight of phenol compounds such as released phenol and cresol could be recovered. The main breakdown of the amount recovered was that phenol was 41 wt%, o-cresol was 29 wt%, p-cresol was 17 wt%, and other (xylenol etc.) was 14 w%.
t%.

[Example 3] Decomposition of phenolic resin molding material In Example 1, instead of the cured phenolic resin,
A decomposition reaction was performed by performing the same operation as in Example 1 except that about 0.57 g of a phenolic resin molding material (resin: 44 wt%, organic filler: 42 wt%, inorganic filler: 14 wt%) was used. As a result, the resin component and the organic filler are almost completely decomposed into water-soluble components and TH.
It became F soluble. Water-soluble and THF-soluble components were analyzed by GC-
Analysis by FID confirmed that about 55 wt% of the resin component (ratio to the whole: 44 wt%) could be recovered as phenol compounds such as phenol and cresol, which were liberated. The breakdown is as follows:
Phenol 38wt%, o-cresol 23wt%
%, P-cresol was 26 wt%, and others (xylenol and the like) were 13 wt%. In addition, the inorganic filler,
It was recovered as a THF-insoluble residue, and was completely separated from the resin and the organic filler.

[Example 4] Decomposition of phenolic resin laminate scraps In Example 1, instead of the cured phenolic resin,
Phenolic resin laminate scrap (paper: 51 wt%, resin: 4
A decomposition reaction was carried out by performing the same operation as in Example 1 except that about 0.5 g (containing 9 wt%) was used. As a result, the resin component and the paper component were almost completely decomposed into a water-soluble component and a THF-soluble component. Water soluble and THF soluble
Analysis by C-FID confirmed that about 60% by weight of the resin component (proportion to the whole: 49% by weight) could be recovered as phenolic compounds such as free phenol and cresol. The amount of phenol was 50 wt% and o-cresol was 20%
wt%, 15 wt% of p-cresol, and 15 wt% of others (such as xylenol).

Example 5 Decomposition of Epoxy Resin Laminated Pieces In Example 1, the epoxy resin laminated board remnants (copper foil: 10.9 wt%,
Glass cloth: 21.7 wt%, filler: 28.2 w
(t%, resin: 39.2 wt%) 0.5 g was used in the same manner as in Example 1 to perform a decomposition reaction.
As a result, the resin component was almost completely decomposed into a water-soluble component and a THF-soluble component. When the water-soluble component and the THF-soluble component were analyzed by GC-FID, about 67 w of the resin component (the ratio to the whole: 39.2 wt%) was obtained.
It was confirmed that t% could be recovered as phenol compounds such as free phenol and cresol. The main breakdown is 30% by weight of phenol and O-
Cresol was 6 wt%, p-cresol was 7 wt%, and isopropyl phenol was 27 wt%. In addition, the copper foil component and the glass cloth were recovered as THF-insoluble residues, and were completely separated from the resin component.

Example 6 In Example 1, 0.20 g of potassium phenoxide was separated and recovered by evaporating the water-soluble component recovered after decomposition. Subsequently, Example 1
, A decomposition reaction was carried out in the same manner as in Example 1, except that 0.20 g of potassium phenoxide obtained by separation and recovery was used as a catalyst. As a result, about 80% by weight of the cured phenolic resin was decomposed into water-soluble matter and THF-soluble matter. When the water-soluble component and the THF-soluble component were analyzed by GC-FID, it was confirmed that about 50% by weight of phenol compounds such as released phenol and cresol could be recovered. The main breakdown is 38% by weight of phenol,
23 wt% o-cresol, 26 w p-cresol
t% and others (xylenol etc.) were 13 wt%.

Comparative Example 1 A decomposition reaction was carried out in the same manner as in Example 1 except that potassium phenoxide used as a catalyst was not added. As a result, the decomposition rate of the cured phenol resin was a very low value of about 15 wt%. When the decomposition products were analyzed by GC-FID, the recovery rate as phenol compounds such as liberated phenol and cresol was about 5 wt%. The main breakdown of the recovered amount was that phenol was 41 wt%, o-cresol was 29 wt%, p-cresol was 17 wt%, and other (xylenol etc.) was 14 wt%.
wt%.

Comparative Example 2 A decomposition reaction was carried out in the same manner as in Example 1 except that 0.25 g of potassium hydroxide was used instead of 0.25 g of potassium phenoxide as a catalyst. . As a result, about 90% by weight of the cured phenolic resin was decomposed into water-soluble components and THF-soluble components, and potassium salts of phenolic compounds such as phenol and cresol were produced. To the potassium salt of these phenolic compounds, sulfuric acid as a neutralizing agent was added in an amount of 0.1%.
When 22 g was added and analyzed by GC-FID,
It was confirmed that about 50 wt% of the free phenolic compounds could be recovered. The main breakdown of the amount recovered was that phenol was 41 wt%, o-cresol was 29 wt%,
The content of p-cresol was 17% by weight, and that of others (xylenol and the like) was 14% by weight. At that time, about 0.39 g of potassium sulfate was generated as a by-product.

[0026]

In the present invention, when a thermosetting resin is hydrolyzed and / or thermally decomposed using supercritical water or subcritical water as a reaction solvent, a salt or alkaline earth composed of an alkali metal and a phenol compound is used as a catalyst. By adding a salt composed of a metal and a phenol compound, the thermosetting resin, which was particularly difficult to decompose, is easily decomposed, and a low to medium molecular compound containing 50% by weight or more of a 1- or 2-nuclear phenol compound is obtained. Can be recovered. The obtained mononuclear phenol compound can be recovered as a free phenol compound, and can be separated and purified without performing a neutralization treatment in a subsequent step.

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Claims (5)

[Claims] 1. A thermosetting resin is hydrolyzed and / or thermally decomposed by using supercritical water or subcritical water as a solvent to form 1-2.
When decomposing into low to medium molecular compounds containing 50% by weight or more of a core phenol compound, a salt composed of an alkali metal and a phenol compound or a salt composed of an alkaline earth metal and a phenol compound is added as a catalyst. Method for decomposing a thermosetting resin. 2. The thermosetting resin is one or more selected from the group consisting of a phenolic resin, an epoxy resin, and a phenol-modified melamine resin,
A method for decomposing a thermosetting resin according to claim 1. 3. A salt comprising an alkali metal and a phenolic compound, wherein the salt comprising an alkali metal selected from the group consisting of lithium, sodium, potassium, rubidium and cesium, phenol, cresol, xylenol, resorcinol, dihydroxydiphenylmethane and 2,2- The method for decomposing a thermosetting resin according to claim 1, wherein the salt is a salt formed with a phenol compound selected from the group consisting of bishydroxyphenylpropane. 4. A salt comprising an alkaline earth metal and a phenolic compound, wherein the salt comprising an alkaline earth metal selected from the group consisting of beryllium, magnesium, calcium, strontium and barium, phenol, cresol, xylenol, resorcinol, dihydroxydiphenylmethane and The method for decomposing a thermosetting resin according to claim 1, wherein the salt is a salt formed with a phenol compound selected from the group consisting of 2,2-bishydroxyphenylpropane. 5. The method according to claim 1, wherein the salt composed of an alkali metal and a phenol compound or the salt composed of an alkaline earth metal and a phenol compound used in the decomposition treatment step is recovered, separated, and reused as a catalyst in the decomposition treatment step. The method for decomposing a thermosetting resin according to any one of claims 1 to 4, characterized in that it is characterized in that: