JP2003096233A - Method for decomposing thermosetting resin and method for recycling the resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rapidly decompose a large quantity of thermosetting resins contained in wastes and reduce the quantity of a solvent consumed by chemical reactions in the decomposing process. SOLUTION: The decomposing process comprises (1) a solid-extracting process in which soluble components (extracts) are extracted by treating thermosetting resin products with water of supercritical or subcritical state and (2) a decomposing process in which components (residue) which are insoluble or slightly soluble in water of supercritical or subcritical state are dissolved in a solvent consisting of a mononuclear phenol compound or water/mononuclear phenol compound of supercritical or subcritical state to decompose them to low or middle molecule compounds consisting mainly of oligomers of molecular weight of 200 to 10,000. In addition, the mononuclear phenol compound used in the decomposing process is separated from the low-to-middle molecular weight compounds thus formed to re-use as the solvent in the decomposing process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solvent consumed by a chemical reaction when decomposing a thermosetting resin contained in a large amount of industrial waste or general waste discarded from factories and the like. It relates to a method for reducing the amount of (mononuclear phenolic compound), and further relates to a recycling method for reusing the low to medium molecular weight compound obtained by this method as a raw material for a thermosetting resin.

[0002]

2. Description of the Related Art Among plastics, thermosetting resins are
Since it has excellent electrical insulation, heat resistance, and mechanical strength, it is widely used as a material for electrical and electronic parts, automobile parts, and so on. However, once the thermosetting resin is once hardened, it is not softened / melted by heat and is not dissolved in a solvent, so that it is technically difficult to regenerate the cured product as a plastic raw material.

In recent years, in order to overcome these problems, a method of decomposing a thermosetting resin using a supercritical fluid has been investigated. For example, a method of hydrolyzing a thermosetting resin and selectively recovering a useful compound using water in a supercritical state or a subcritical state has been investigated (Japanese Patent Laid-Open No. 10-29138).
No. 24274). When this method is used, a thermosetting resin having an ether bond, an ester bond, or an acid amide bond in the structure, such as an acid anhydride cured product of an epoxy resin or an aromatic diamine cured product, is used as an acid catalyst or an alkali catalyst. Without adding, it can be completely decomposed under the conditions of 400 ° C., 37 MPa, and 10 minutes until it is completely soluble in tetrahydrofuran (THF). However, even with an epoxy resin, a thermosetting resin having methylene in its structure such as a cured product of phenol novolac has the same temperature of 400 ° C. and 37 ° C.
The decomposition rate under the condition of MPa for about 10 minutes is about 50 wt%, which is not a very high value. Further, a cured product of a phenol resin is extremely hard to decompose even in supercritical water, and under the conditions of 400 ° C., 37 MPa, and 10 minutes, T
About 20 wt% decomposes to HF solubility.

Therefore, in order to decompose and recycle the hardly decomposable thermosetting resin by using these supercritical water alone, a mononuclear phenol compound or water / mononuclear phenol in a supercritical or subcritical state is used. A method of solubilizing treatment in a solution of a similar compound has been studied (JP 2001-151A).
933 publication). In this method, the thermosetting resin is solubilized in a short reaction time of about 10 minutes without adding an acid catalyst or an alkali catalyst to give a molecular weight of 200 to 10,000.
It is said that 0 oligomer components can be recovered.

In the above method, the mononuclear phenol compound acts as a reaction substrate as well as a solvent, and is consumed for the solubilization reaction of the thermosetting resin. Here, when the thermosetting resin is a composite material containing an organic natural polymer or synthetic polymer such as wood powder, paper, cloth, etc., the mononuclear phenol compound is a solubilization reaction of the thermosetting resin component. Not only is it consumed in the solubilization reaction or decomposition reaction of organic natural polymers or synthetic polymers. That is, when the content of organic natural polymers or synthetic polymers such as wood powder, paper, cloth, etc. contained in the thermosetting resin is high, the mononuclear phenolic compound is rather a chemical reaction of the natural polymer. As a result, it is consumed in large amounts, and the amount used is large.

As described above, a technique for efficiently decomposing a thermosetting resin in a short time, recovering, separating, purifying and reusing it as a useful low-to-medium molecular compound is being established. Therefore, there is a problem that the consumption of mononuclear phenolic compounds is large, and it is necessary to devise to reduce the consumption.

[0007]

The present invention has been made as a result of various studies in order to solve such problems. Its main purpose is to produce large amounts of thermosetting resin, which is contained in large amounts in industrial waste discharged from factories and general waste, but has not been recyclable up to now, at high speed. It provides a recycling method that decomposes and separates and recovers the obtained low to medium molecular weight compounds, and reuses it as a raw material for thermosetting resins, and consumes it by a chemical reaction during the decomposition process. It is an object of the present invention to provide a method for reducing the amount of a solvent (mononuclear phenolic compound) to be used.

[0008]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted a solid extraction treatment of a thermosetting resin product (waste) with water in a supercritical state or a subcritical state. Solvent (mononuclear phenolic compound) consumed by chemical reaction by decomposition treatment in specific solution in subcritical state
It has been found that the resin content of the thermosetting resin can be decomposed to the raw material level while reducing the amount of the above, and further studies have been conducted to complete the present invention.

That is, the present invention provides (1) a solid extraction step in which a thermosetting resin product is treated with water in a supercritical state or a subcritical state to extract and separate soluble components (extractants), and (2)
Solubilization of insoluble or sparingly soluble components (extracts) in supercritical or subcritical water using supercritical or subcritical mononuclear phenol compounds or water / mononuclear phenol compounds as solvent By processing, the molecular weight of 200-10,
000 oligomers as a main component, which decomposes into low to medium molecular weight compounds, and further separates the mononuclear phenolic compound used in the decomposition step from the produced low to medium molecular weight compounds, and decomposes again. Is a method for decomposing a thermosetting resin, which is characterized in that it is used as a solvent in, and a low to medium molecular weight compound obtained by decomposing the thermosetting resin is reused as a raw material for the thermosetting resin. And a method for recycling a thermosetting resin.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The thermosetting resin decomposed by the method of the present invention is, by itself, a cured resin, an uncured resin, a varnish containing a resin, or the like. In addition to resins, organic materials such as wood powder, silica fine particles,
A molding material or molded product containing an inorganic filler such as glass fiber, a laminate using an organic base material such as paper or cloth or an inorganic base material such as glass cloth, and a metal foil such as a copper foil laminated to this It also includes a metal-clad laminate, and a thermosetting resin product such as a printed circuit board obtained by processing a copper-clad laminate.

According to the present invention, a thermosetting resin containing these thermosetting resin products and wastes thereof is subjected to a solid extraction treatment with water in a supercritical state or a subcritical state to obtain a soluble component (extractant) in advance. ) Is extracted and separated, and the insoluble or sparingly soluble component (extract) is solubilized using a supercritical or subcritical mononuclear phenol compound or water / mononuclear phenol compound as a solvent. The aim is to reduce the amount of solvent (mononuclear phenolic compound) consumed by the chemical reaction, and further, to reduce the amount of mononuclear phenolic compound used in the decomposition step (solubilization treatment). ~ Separated from the medium-molecular weight compound and used again as a solvent in the decomposition step, or try to reuse the low-medium-molecular weight compound obtained by decomposing the thermosetting resin as a raw material of the thermosetting resin It is a thing.

The type of thermosetting resin is not particularly limited, but in the present invention, a phenol resin, an epoxy resin, a polyimide resin, an unsaturated polyester resin,
Suitable for melamine resin, urea resin, etc.,
Of these, phenol resin, epoxy resin, melamine resin and urea resin can be applied particularly effectively.
Further, two or more of these may be mixed.

The size of the thermosetting resin to be used is not particularly limited, but is 0.1-10 mm in advance so that the solubilization reaction proceeds in a shorter time.
It is preferable to grind to a degree.

In the solid extraction step of the present invention, the proportion of water used in the supercritical state or subcritical state for the thermosetting resin is 50 to 100 parts by weight of the thermosetting resin.
The preferred range is 1,000 parts by weight, preferably 10 parts.
It is in the range of 0 to 200 parts by weight. If the proportion of water used is less than the above range, the efficiency of extracting the water-soluble organic component (extractant) in the supercritical or subcritical state from the thermosetting resin decreases. On the other hand, if the amount exceeds the above range, no particular effect is obtained and the amount of heat required to heat water increases, which is disadvantageous in terms of thermal energy.

The solid extraction step is carried out under conditions of high temperature and high pressure. Temperature is about 200-500 ° C, pressure is 1-45
The temperature and the pressure may be adjusted to supercritical or subcritical conditions within a range of about Mpa, but preferably the temperature is 25
The temperature and pressure may be set in the range of 0 to 400 ° C. and the pressure of 2 to 35 MPa. The treatment time can be adjusted in the range of 1 to 60 minutes, but it is usually completed in 5 to 30 minutes. If the temperature is higher than the above range, or if the time is longer than the above range, the polymerization reaction or carbonization reaction of the thermosetting resin proceeds, and the thermosetting resin becomes more difficult to decompose. That is,
Since the efficiency of the solubilization reaction in the subsequent decomposition step is reduced and the chemical structure of the recovered oligomer is altered, it becomes difficult to reuse the thermosetting resin product as a chemical raw material.

The mononuclear phenolic compound used in the decomposition step of the present invention is preferably phenol, cresol, xylenol, resorcin, alkyl-substituted phenol, etc., and one or more kinds selected from the group consisting of these are used. You can Phenol is particularly preferable in terms of cost and effect on the solubilization reaction.

In the decomposition step, when a mixture of water and a mononuclear phenol compound is used, the ratio of both is preferably 1 part by weight and 500 is an upper limit with respect to 100 parts by weight of the mononuclear phenol compound. Parts by weight, more preferably the lower limit value is 5 parts by weight and the upper limit value is 50 parts by weight.

The proportion of water / mononuclear phenolic compound used for the thermosetting resin is preferably 50 to 2,000 parts by weight, and more preferably 100 parts by weight of the thermosetting resin. It is in the range of 200 to 400 parts by weight. If the ratio of water / mononuclear phenol compound used is less than the above range, it becomes difficult to smoothly proceed the solubilization reaction of the thermosetting resin. On the other hand, if the amount exceeds the above range, no particular effect can be obtained and the amount of heat required to heat the solvent increases, which is disadvantageous in terms of thermal energy.

The decomposition step is carried out under conditions of high temperature and high pressure, and the temperature is about 200 to 500 ° C. and the pressure is 1 to
The temperature and pressure may be adjusted to supercritical or subcritical conditions in the range of about 60 MPa, but it is preferable to set the temperature and pressure in the range of 300 to 450 ° C. and 2 to 40 MPa. When the temperature is lower than the above range, the solubilization reaction rate of the thermosetting resin is low, and thus it becomes difficult to perform the treatment in a short time. On the other hand, when the temperature is higher than the above temperature range, side reactions such as thermal decomposition occur concurrently and the chemical structure of the recovered oligomer changes, so that it becomes difficult to reuse the thermosetting resin product as a chemical raw material. The reaction time can be adjusted in the range of 1 to 60 minutes, but usually 3 to
The disassembly process ends in 30 minutes.

In the decomposition step, a reaction catalyst such as an acid or alkali catalyst can be used, but in the method of the present invention, the decomposition treatment can be carried out without using a reaction catalyst containing them. The advantage is that the subsequent catalyst separation operation is not necessary.

Following the decomposition step, after separating the solid content, water and phenols are separated from the liquid content by a method such as distillation or extraction. The rest is molecular weight 200-1
It is a low-to-medium molecular weight compound mainly composed of 000 oligomers, and further purified if necessary.

The thus obtained phenols containing water and mononuclear phenolic compounds can be prepared by adding water or mononuclear phenolic compounds newly, if necessary.
Again, it can be used as a solvent in the decomposition step. The soluble component (extractable substance) extracted and separated in the solid extraction step is one or more selected from the group consisting of natural polymers or synthetic polymers such as wood flour, paper and cloth. ,
By extracting and separating these in advance, the consumption of the mononuclear phenolic compound in the decomposition step is reduced, but further, by collecting the unreacted mononuclear phenolic compound after the decomposition step and reusing it, The required amount of mononuclear phenolic compound can be significantly reduced.

On the other hand, after separation of phenols, low-molecular weight oligomers having a molecular weight of 200 to 10,000 are mainly used.
The medium molecular weight compound can be reused (recycled) as a raw material of the thermosetting resin.

This low to medium molecular weight compound recovered from the thermosetting resin is usually of the same molecular weight as the prepolymer used in producing the thermosetting resin product,
It can be reused as a chemical raw material (prepolymer) for thermosetting resin products by performing purification and modification as necessary. Here, the term "mainly composed of an oligomer having a molecular weight of 200 to 10,000" means that an oligomer having the molecular weight shown here is contained in an amount of 50% or more. Over 1,000 oligomers are also included. Further, as an oligomer having a molecular weight of 200 to 10,000, in the case of a usual thermosetting resin, it is about 2 to 100 nuclei of a raw material monomer.

The insoluble or sparingly soluble components (extracts) that are not extracted in the solid extraction step of the present invention include carbon fibers, organic fillers such as carbon fine particles, phenol resins, epoxy resins, polyimides, A cured product of thermosetting resin such as unsaturated polyester resin, melamine resin, urea resin, silica fine particles, inorganic filler such as glass fiber, metal such as gold wire, copper foil, or the like. One or more selected from these groups. Among these, the cured product of the thermosetting resin is decomposed and solubilized in the decomposition step of the present invention.

[0026]

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

Example 1 A decomposition solid extraction step of a phenol resin molding material was carried out by the following operation. Small batch reactor (internal volume 5 cm ³ , Hastelloy C-276
Phenol resin molding material (resin: 44 wt%, organic filler: 4) crushed to a particle size of 0.25-0.50 mm
2 wt%, inorganic filler: 14 wt% contained) 1 g and water 3 g were charged, and the inside was replaced with argon and sealed. Put the reactor in a fluidized sand bath and heat rapidly to increase the internal temperature to 25
By setting the temperature to 0 ° C., the internal pressure of the reactor was increased to 4 MPa, and a high temperature and high pressure state was obtained. After maintaining at 250 ° C. and 4 MPa for 10 minutes, the reactor was cooled with an air gun and returned to normal temperature and normal pressure. After the solid extraction operation was completed, the product in the reactor was recovered and filtered with a 1.0 μm filter to separate into a water-soluble component and a water-insoluble component. As a result, the amount of raffinate, which is a water-insoluble matter, was 0.87 g, and 0.13 g was extracted as a water-soluble matter (filtrate).

Subsequently, the decomposition step was carried out by the following operation.
The above small batch type reactor was charged with 0.87 g of the raffinate after the above solid extraction step, 1.5 g of water and 1 g of phenol,
The inside was replaced with argon and then sealed. The reactor was put into a fluidized sand bath and heated rapidly to bring the internal temperature to 360 ° C., whereby the internal pressure of the reactor was raised to 3 MPa, and a high temperature and high pressure state was obtained. After maintaining at 360 ° C. and 6 MPa for 30 minutes, the reactor was cooled with an air gun and returned to room temperature and normal pressure. The product after the decomposition reaction was dissolved in water and then filtered through a 1.0 μm filter to give a filtrate as a water-soluble component. The water-insoluble matter remaining on the filter after filtration was dissolved in tetrahydrofuran (hereinafter abbreviated as THF) and then 1.0 μm.
It was filtered with a filter of m, and the filtrate was used as a THF-soluble component.
The THF insoluble matter (residue) remaining on the filter is heated to 100 ° C.
It was dried for 12 hours and weighed to be 0.15 g. Most of this residue was the inorganic filler contained in the phenolic resin molding material.

When the above water-soluble matter was analyzed by gas chromatography (detector FID) (hereinafter abbreviated as GC-FID), the amount of phenol added as a solvent consumed by the reaction was 0.65 g. Met. Also, T
The HF-soluble matter was analyzed by gel permeation chromatography (hereinafter abbreviated as GPC). As a result, a number average molecular weight (hereinafter referred to as Mn) 740, a weight average molecular weight (hereinafter referred to as Mw) 5 It was confirmed that 1,500 oligomers were produced.

[Examples 2 to 7] In Example 1 of decomposing a phenol resin molding material, except that the temperature and treatment time of the solid extraction step or the temperature and treatment time of the decomposition step were changed as shown in Table 1. The decomposition treatment was carried out in the same manner as in Example 1.
The results of the decomposition treatment are summarized in Table 1.

[0031]

[Table 1]

Example 8 Decomposition of Phenolic Resin Molding Material The solid extraction step was carried out in the same manner as in Example 6 to obtain a raffinate amount of 0.69 g and a water-soluble component of 0.11 g. This raffinate was decomposed by the same operation as in Example 6, and the water-soluble matter recovered after the decomposition was distilled under reduced pressure to give 1.8 g of a water / phenol mixed solution (1.3 g of water, 0.5 g of phenol). Separated. Then, this water / phenol mixed solution 1.8
The decomposition step was performed in the same manner as in Example 6 except that 0.2 g of water and 0.5 g of phenol were newly added to g to use as a reaction solvent. The results of the decomposition treatment are shown in Table 1.

Comparative Example 1 Decomposition of Phenolic Resin Molding Material Using the same small batch reactor and sample (phenolic resin molding material) as in Example 1, 1 g of sample, 1.5 g of water, and 1 g of phenol were placed in the reactor. After charging, the inside was replaced with argon and then sealed. Put the reactor in a fluidized sand bath and heat it rapidly to bring the internal temperature to 360 ° C.
It was raised to Pa and brought into a high temperature and high pressure state. 360 ° C, 3
After holding for 30 minutes at MPa to carry out the decomposition reaction, the reactor was cooled with an air gun and returned to room temperature and atmospheric pressure. The product after the decomposition reaction was treated as in Example 1,
0.15 g of a THF insoluble residue was obtained. Most of this residue was the inorganic filler contained in the phenolic resin molding material.

When the water-soluble matter was analyzed by GC-FID, the amount of phenol added as a solvent consumed by the reaction was 0.77 g. Further, the THF-soluble matter was analyzed by GPC, and Mn740, Mw
It was confirmed that 5,700 oligomers were produced.

[Comparative Examples 2 to 3] Decomposition of Phenolic Resin Molding Material In Comparative Example 1, except that the temperature and the treatment time were changed.
The decomposition treatment was performed by the same operation as in Comparative Example 1. The results of the decomposition treatment are summarized in Table 1.

Comparative Example 4 Decomposition of Phenolic Resin Molding Material In Comparative Example 2, the water-soluble component recovered after decomposition was distilled under reduced pressure to obtain 1.8 g of a water / phenol mixed solution (water 1.
3 g, phenol 0.2 g) were separated. Decomposition treatment was carried out in the same manner as in Comparative Example 2 except that 0.2 g of water and 0.8 g of phenol were newly added to the mixture as a reaction solvent. The results of the decomposition treatment are shown in Table 1.

As can be seen from the decomposition treatment results shown in Table 1, in the decomposition treatment method of the present invention shown in Examples 1 to 8,
Compared to the decomposition treatment methods shown in Comparative Examples 1 to 4, the consumption of phenol was obviously smaller. On the other hand, the amount of residue after the decomposition step and the molecular weight of the decomposition product were the same value.

[Examples 9 and 10] Decomposition of Paper-Based Phenolic Resin Laminated Board In Example 1, a paper-based phenolic resin laminated board was used in place of the phenol resin molding material, and the temperature and treatment time of the solid extraction step were used. The decomposition treatment was performed in the same manner as in Example 1 except that the temperature of the decomposition step and the treatment time were changed as shown in Table 2. The results of the decomposition treatment are summarized in Table 2.

[0039]

[Table 2]

[Comparative Examples 5 and 6] In the decomposition comparison 1 of the paper-based phenol resin laminate, instead of the phenol resin molding material,
Using a paper-based phenolic resin laminate, the temperature of the decomposition process,
Comparative Example 1 except that the treatment time was changed as shown in Table 2
The decomposition process was performed by the same operation as. Table 2 shows the decomposition results
Shown in.

As can be seen from the decomposition treatment results shown in Table 2, in the decomposition treatment method of the present invention shown in Examples 9 and 10, compared with the decomposition treatment methods shown in Comparative Examples 5 and 6, phenol was used. The consumption was obviously low. On the other hand, the amount of residue after the decomposition step and the molecular weight of the decomposition product were the same value.

[0042]

According to the present invention, the thermosetting resin, which has been contained in a large amount in industrial wastes or general wastes but has not yet been recycled, is treated with water in a supercritical or subcritical state. After the solid extraction treatment with, the raffinate is decomposed using a mononuclear phenol compound or a water / mononuclear phenol compound mixture in a supercritical or subcritical state as a reaction solvent to give a molecular weight of 200 to 10,0
High-speed and large-scale decomposition of low to medium molecular weight compounds mainly composed of oligomers of 00 can be performed, and the amount of solvent (mononuclear phenolic compound) consumed by chemical reaction at that time can be reduced. be able to. Further, the low-to-medium molecular weight compound mainly composed of the recovered oligomer having a molecular weight of 200 to 10,000 can be reused as a raw material of the thermosetting resin.

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Claims (5)

[Claims] 1. A thermosetting resin product is treated with water in a supercritical state or a subcritical state to extract a soluble component (extractant).
A solid extraction step of separating, and (2) a supercritical or subcritical water-insoluble or sparingly soluble component (extract) to a supercritical or subcritical mononuclear phenolic compound or water /
A thermosetting resin comprising a decomposition step of decomposing into a low to medium molecular weight compound mainly composed of an oligomer having a molecular weight of 200 to 10,000 by solubilization treatment using a mononuclear phenol compound as a solvent. Disassembly treatment method. 2. The thermosetting resin is one or more selected from the group consisting of phenol resin, epoxy resin, polyimide, unsaturated polyester resin, melamine resin and urea resin. The decomposition treatment method of the thermosetting resin according to claim 1. 3. The mononuclear phenol compound is one or more selected from the group consisting of phenol, cresol, xylenol, resorcin, and alkyl-substituted phenol, or claim 1 or claim 2. 2. The method for decomposing a thermosetting resin according to item 2. 4. The mononuclear phenolic compound used in the decomposition step is separated from the produced low to medium molecular weight compound and reused as a solvent in the decomposition step. A method for decomposing a thermosetting resin as described in (1). 5. A low-to-medium molecular weight compound obtained by decomposing a thermosetting resin by the decomposition treatment method according to any one of claims 1 to 4 is reused as a raw material for the thermosetting resin. A method for recycling a thermosetting resin, characterized by: