JP2003253041A - Method for decomposing thermosetting resin and method for recycling thermosetting resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a decomposition method whereby a thermosetting resin contained in a large amount in wastes can be decomposed speedily on a large scale, and the solid component contained in the slurry is inhibited from being agglomerated and settled during the decomposition treatment to accomplish a high decomposition rate. <P>SOLUTION: The method for decomposing the thermosetting resin comprises slurrying the thermosetting resin and decomposing it in a supercritical or subcritical state in a reaction solvent being a mononuclear phenol or a mixture thereof with water to obtain an oligomer-based low to medium molecular weight compounds. The thermosetting resin is slurried by mixing the reaction solvent with a dispersant comprising a phenol resin. A method for recycling the thermoplastic resin comprises recycling the oligomer-based low to medium molecular weight compounds as materials for a thermosetting resin. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a decomposition treatment method and a recycling method for thermosetting resins.
More specifically, it decomposes a large amount of industrial waste that has been discarded in large quantities from factories, etc., and thermosetting resins that are not contained in general waste and have not been recycled so far, at high speed. The present invention relates to a method for decomposing a thermosetting resin that can be used, and a method for recycling a thermosetting resin, in which a low to medium molecular weight compound obtained by the decomposing method is reused 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, thermosetting resins, once cured,
Since it does not soften / melt by heat and does not dissolve in a solvent, 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, in order to decompose and recycle a thermosetting resin that is difficult to decompose with supercritical water alone, it may be used in a solution of a mononuclear phenol compound or a water / mononuclear phenol compound in a supercritical or subcritical state. A method of solution treatment has been studied (Japanese Patent Laid-Open No. 2001-151933). According to 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, and an oligomer component having a molecular weight of 200 to 10,000 can be recovered.

In recycling the thermosetting resin by the above method, there is a problem of decomposition efficiency of the thermosetting resin,
In order to improve the decomposition efficiency, a method of mixing the thermosetting resin and the reaction solvent in advance and decomposing as a high-concentration slurry can be considered, but agglomeration and sedimentation of solids in the slurry occur during heating and reaction. As a result, the decomposition efficiency is lowered and a polymer is produced, or the polymer is attached to the inner wall of the reaction tube to lower the heat conduction efficiency. Furthermore, when continuously decomposing with a flow-through apparatus, the slurry supply pipes and reaction pipes may be blocked due to agglomeration and sedimentation of solids in the slurry, so that the decomposing process may not be possible.

[0005]

DISCLOSURE OF THE INVENTION The present invention is a thermosetting resin which can stably achieve a high decomposition rate by suppressing the aggregation / sedimentation of solids in a high-concentration slurry in the temperature rising process and the decomposition reaction process. It is intended to provide a resin decomposition treatment method and a recycling method.

[0006]

DISCLOSURE OF THE INVENTION The inventors of the present invention formed a slurry composed of a thermosetting resin and a reaction solvent by using a dispersant capable of improving the stability of the slurry, and made it supercritical or subcritical. It has been found that the decomposition efficiency of the thermosetting resin can be improved by performing the decomposition treatment of the thermosetting resin under the condition, and the present invention has been completed.

That is, according to the present invention, (1) a thermosetting resin is slurried and a mononuclear phenol compound or a mixture of water and a mononuclear phenol compound is used as a reaction solvent in a supercritical or subcritical state. , 200-10,0
A method of decomposing a low molecular weight compound to a medium molecular weight compound mainly composed of an oligomer having a molecular weight of 00, wherein a thermosetting resin is slurried by mixing the reaction solvent and a dispersant composed of a phenol resin. A method for decomposing a thermosetting resin, characterized in that (2) a dispersant comprising a phenol resin is synthesized by subjecting a phenol and an aldehyde to a polycondensation reaction, and a molecular weight of 200 to 100,000.
Novolak type phenolic resin or resol type phenolic resin of 0.0 to 100 parts by weight of the slurry.
5 to 20 parts by weight of the method for decomposing the thermosetting resin according to (1) above, (3) wherein the mononuclear phenol compound is phenol, cresol, xylenol,
A method for decomposing a thermosetting resin according to the above (1) or (2), which is selected from resorcin and alkyl-substituted phenol, (4) a mononuclear phenol compound or water and a mononuclear phenol The mixture with the compound is obtained by separating and purifying from a low to medium molecular weight compound mainly composed of an oligomer having a molecular weight of 200 to 10,000 produced by decomposition treatment and purifying the mixture. ) To the method for decomposing a thermosetting resin according to any one of (3) to (3), (5) the thermosetting resin is a phenol resin, an epoxy resin, a polyimide resin, an unsaturated polyester resin, a melamine resin, and The method for decomposing a thermosetting resin according to any one of (1) to (4) above, which is one kind or two or more kinds selected from urea resins.
(6) Mainly composed of an oligomer having a molecular weight of 200 to 10,000 obtained by decomposing a thermosetting resin by the decomposition treatment method according to any one of the items (1) to (5). The present invention provides a method for recycling a thermosetting resin, in which a low to medium molecular weight compound is reused as a raw material for a thermosetting resin.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A method for decomposing a thermosetting resin of the present invention is to prepare a slurry of a thermosetting resin to be decomposed,
Low molecular weight mainly composed of an oligomer having a molecular weight of 200 to 10,000, which is decomposed in a supercritical or subcritical state using a mononuclear phenol compound or a mixture of water and a mononuclear phenol compound as a reaction solvent. Is a method of decomposing into a medium molecular weight compound, and in the slurry formation, a thermosetting resin to be decomposed, the reaction solvent, and a dispersant composed of a phenol resin are mixed to form a slurry. It is what

In the present invention, as a phenol resin used as a dispersant in slurry formation, a novolac type phenol resin or a resol type phenol resin synthesized by subjecting a phenol and an aldehyde to a polycondensation reaction is preferable. Examples of phenols include phenol, dihydric phenols such as resorcinol and catechol, alkyl-substituted phenols such as cresol and xylenol, bisphenol A, bisphenol F, and bisphenol S.
And other binuclear phenols, and any of them may be used. Examples of aldehydes include formalin, paraformaldehyde, benzaldehyde, acetaldehyde and the like, and any of them may be used. Among these, the novolac type phenol resin synthesized from phenol and formalin is preferable in terms of cost.

The weight average molecular weight of the phenol resin used as the dispersant in the slurry formation is 200 to 100,0.
The range is about 00, preferably 200 to 50,0
00, and more preferably in the range of 400 to 20,000. When the molecular weight is lower than the above range, the effect on the slurry stability may not be obtained. On the other hand, when the molecular weight is higher than the above range, the solubility of the phenol resin in the reaction solvent may be poor, and in that case, the mixing time required for adjusting a uniform slurry becomes long.

The addition amount of the phenol resin used as the dispersant in slurry formation is preferably in the range of 0.05 to 20 parts by weight with respect to 100 parts by weight of the slurry,
More preferably, it is in the range of 0.1 to 5 parts by weight. If the amount added is less than the above range, the effect on the slurry stability may not be obtained. Further, when the addition amount is more than the above range, the effect is not significantly improved as compared with the effect of the preferred upper limit and the cost becomes high, and further, the viscosity of the slurry is excessively increased, and thus the fluidity is lowered. , It may adversely affect the decomposition reaction.

In the present invention, the slurry is formed by mixing the thermosetting resin, the reaction solvent and the dispersant using a mixing device such as a ribbon mixer, a ball mill and a wet pulverization stirrer. Before mixing, the thermosetting resin is solid, liquid, paste, etc., the reaction solvent is liquid, the dispersant is solid,
It may be in a semisolid, liquid or varnish state. Also,
The order in which the thermosetting resin, the reaction solvent, and the dispersant are mixed is not particularly limited, but usually, a solution in which the dispersant is dissolved in the reaction solvent is prepared in advance, and then the thermosetting resin is added to the slurry. It is efficient if it is made into. Further, when making a slurry, it is efficient to perform the treatment while heating at about 40 to 100 ° C.

Preferable examples of the mononuclear phenol compound used as the reaction solvent in the present invention include phenol, cresol, xylenol, resorcin, and alkyl-substituted phenol, and one or more of these are used. Of these, phenol is preferable in terms of cost and effect on the decomposition reaction.

In the present invention, it is used as a reaction solvent,
The composition of the mixed solvent of water and the mononuclear phenol compound is 0 to 500 parts by weight of water based on 100 parts by weight of the mononuclear phenol compound.
The range is preferably 5 parts by weight, and more preferably 5 to 50 parts by weight with respect to 100 parts by weight of the mononuclear phenolic compound.

In the present invention, the proportion of the mononuclear phenolic compound or the mixture of water and mononuclear phenolic compound used for the thermosetting resin to be decomposed is 100 parts by weight of the thermosetting resin. The range of 50 to 1000 parts by weight is preferable, and the range of 100 to 400 parts by weight is more preferable. When the amount of the mononuclear phenol compound or the mixture of water and the mononuclear phenol compound is less than the above range, it may be difficult to smoothly proceed the decomposition reaction of the thermosetting resin. On the other hand, when the amount is more than the above range, no particular effect is obtained compared to the effect of the preferable upper limit value, and in that case, the amount of heat required to heat the solvent increases, so that the heat energy consumption increases.

The thermosetting resin decomposed by the method of the present invention includes a cured resin, an uncured or semi-cured resin, a resin-containing varnish and the like. Further, in addition to a single thermosetting resin, fine particles of silica, inorganic fibers such as glass fibers, molding materials or molded products containing organic fillers such as wood powder, inorganic materials such as glass cloth, and paper. , A laminated board using an organic base material such as cloth, a metal-clad laminated board in which a metal foil such as a copper foil is laminated, and a heat such as a printed circuit board obtained by processing a copper-clad laminated board. Curable resin products are also included. The type of thermosetting resin is not particularly limited, the present invention is a phenol resin, an epoxy resin, a polyimide resin,
It can be applied particularly effectively to unsaturated polyester resins, melamine resins and urea resins.

The present invention can recover 20 from thermosetting resins.
A low to medium molecular weight compound mainly composed of an oligomer having a molecular weight of 0 to 10,000 usually has a molecular weight similar to that of a prepolymer used in producing a thermosetting resin product, and thus is required. By carrying out purification accordingly, it can be reused as a chemical raw material (prepolymer) of a thermosetting resin product.

The size of the thermosetting resin used for the decomposition treatment is not particularly limited, and the optimum size may be selected in consideration of the cost required for pulverization, the decomposition rate and the stability of the slurry. In order to adjust a stable slurry, the particle size is usually 500 μm or less, preferably 250 μm.
Hereafter, it is more preferably 100 μm or less.

In the present invention, as decomposition conditions, temperature and pressure are usually 200 to 500 ° C. and 1
It may be prepared under the conditions of supercritical or subcritical in the range of ˜60 Mpa, but desirably the temperature is 300 to 450 ° C.,
The temperature and pressure may be set within a pressure range of 2 to 40 MPa. When the temperature is lower than the above range, the decomposition reaction rate of the thermosetting resin is small, and thus the treatment in a short time becomes difficult. On the other hand, when it is higher than the above 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 the decomposition treatment is usually completed in about 3 to 30 minutes.

The method for decomposing and recycling a thermosetting resin of the present invention is a method for preparing a mononuclear phenol compound or water and a mononuclear phenol compound in a supercritical or subcritical state without using an acid or alkali catalyst. By decomposing the thermosetting resin in a solvent composed of a mixture, a low to medium molecular weight compound mainly composed of an oligomer having a molecular weight of 200 to 10,000 can be recovered. Further, the low to medium molecular weight compound mainly composed of the oligomer having a molecular weight of 200 to 10,000 recovered by the above method can be reused as a raw material of the thermosetting resin. An example of these steps can be shown as in the flow chart of FIG. The phenol resin added as a dispersant also decomposes, but the product is
Since it is a low to medium molecular weight compound consisting mainly of oligomers having a molecular weight of 10,000, it does not need to be separated from decomposition products derived from thermosetting resins and can be reused as it is as a raw material for thermosetting resins. Being able to do so is a great advantage.

[0021]

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

[Example 1] Decomposition of phenol resin molding material As a thermosetting resin, phenol resin molding material (novolac type phenol resin: 44 wt%, organic filler (wood powder etc.): 42 wt%, inorganic filler (calcium carbonate etc.) ): 14 wt%) was pulverized and sieved to adjust the particle size to 250 μm or less. 58.3 g of the above-mentioned phenol resin molding material and 85.6 of phenol
When mixed with a reaction solvent consisting of a mixture of 1 g and 21.3 g of water, the number average molecular weight (hereinafter, Mn) of 1000 was synthesized by reacting phenol and formaldehyde while heating the system to 60 ° C. , Weight average molecular weight (hereinafter, M
w) 1.0 g of 10,000 novolak type phenolic resin (PR-50731 manufactured by Sumitomo Dures Co., Ltd.) was added to form a slurry. The above slurry was charged into an autoclave (internal volume: 200 cm ³ ), and then heated to an internal temperature of 400 ° C. to raise the internal pressure of the reactor to 15 MPa to bring it to a high temperature and high pressure state. 400 ° C, 15 MPa
After keeping it for 5 minutes, it was cooled and returned to normal temperature and pressure. After completion of the reaction, the mixture of the decomposition product and the reaction solvent is heated under normal pressure and reduced pressure conditions to remove the solvent (phenol,
(Water) was removed to obtain 64 g of a decomposition product. This product was dissolved in tetrahydrofuran (THF) and then filtered with a filter having a pore size of 1.0 μm to obtain a filtrate as a THF-soluble component. The water-insoluble matter remaining on the filter after filtration was dried, and the THF-insoluble residue remaining on the filter was dried at 100 ° C. for 12 hours and then weighed. As a result, most of the THF insoluble residue is the inorganic filler in the phenol resin molding material, and the resin and the organic filler are almost 100%.
It was confirmed that 100% was decomposed to THF-soluble content. This T
When the molecular weight of the HF soluble component was analyzed by gel permeation chromatography (hereinafter abbreviated as GPC), it was confirmed to be an oligomer with Mn: 750 and Mw: 2800.

Example 2 Decomposition of Phenolic Resin Molding Material In Example 1, Mn: 760, M synthesized by reacting phenol and formaldehyde as a dispersant.
w: 1,300 Novolak type phenolic resin (PR-51714 manufactured by Sumitomo Durez Co., Ltd.) was used, except that
The same operation as in Example 1 was performed to carry out the decomposition reaction. The results of the decomposition treatment are summarized in Table 1.

[0024]

[Table 1]

Example 3 Decomposition of Phenolic Resin Molding Material In Example 1, Mn: 240, M synthesized by reacting phenol and formaldehyde as a dispersant.
A decomposition reaction was performed in the same manner as in Example 1 except that a resol type phenolic resin w: 440 (PR-51501B manufactured by Sumitomo Durez Co., Ltd.) was used. The results of the decomposition treatment are summarized in Table 1.

Example 4 Decomposition of Phenolic Resin Molding Material Decomposition reaction was performed in the same manner as in Example 1 except that the amount of the novolac type phenol resin added as a dispersant was 0.3 g. I went. The results of the decomposition treatment are shown in Table 1.

[Comparative Example 1] The decomposition reaction was carried out in the same manner as in Example 1 except that no dispersant was added. The results of the decomposition treatment are shown in Table 1.

[Comparative Example 2] In Example 1, except that as the dispersant, a sodium salt of naphthalenesulfonic acid formalin condensate (Destrol SH manufactured by Nippon Emulsifier Co., Ltd.) which is an anionic surfactant was added. The same operation as in Example 1 was performed to carry out the decomposition reaction. The results of the decomposition treatment are shown in Table 1.

As can be seen from the results shown in Table 1, in the decomposition treatment methods shown in Examples 1 to 4, the decomposition rate of the resin component and the organic filler was almost 100%, and the polymerized material was formed on the inner wall of the reaction vessel. There was no adhesion. On the other hand, Comparative Example 1,
In the decomposition treatment method of Comparative Example 2, the decomposition rate of the resin component and the organic filler was about 80 to 85%, and the black polymer adhered to the inner wall of the reaction vessel. In Comparative Example 1 and Comparative Example 2,
Due to insufficient stability of the slurry, solid components in the slurry settled and agglomerated during heating and reaction, resulting in insufficient contact with the reaction solvent and the decomposition reaction did not proceed sufficiently. is there. On the other hand, in Examples 1 to 3, the decomposition reaction proceeded efficiently because the stability of the slurry was improved by the effect of the phenol novolac added to the slurry as the dispersant.

[0030]

According to the present invention, it is possible to suppress the aggregation / sedimentation of the solid content in the slurry, achieve a high decomposition rate, and suppress the formation of a polymer. Further, the decomposition product containing a low to medium molecular weight compound mainly composed of an oligomer having a molecular weight of 200 to 10,000 recovered by the above method can be reused as a raw material of a thermosetting resin.

[Brief description of drawings]

FIG. 1 is a flowchart showing an example of a decomposition treatment method and a recycling method of the present invention.

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Claims (6)

[Claims] 1. A thermosetting resin is slurried, and a mononuclear phenolic compound or a mixture of water and a mononuclear phenolic compound is used as a reaction solvent in a supercritical or subcritical state to obtain 200 to 10,000 A method for decomposing a low molecular weight to a medium molecular weight compound mainly composed of an oligomer having a molecular weight, wherein a thermosetting resin is made into a slurry by mixing the reaction solvent and a dispersant consisting of a phenol resin. A method for decomposing a thermosetting resin, the method comprising: 2. The slurry 100 is a novolac-type phenol resin or a resole-type phenol resin having a molecular weight of 200 to 100,000, which is synthesized by polycondensation reaction of phenols and aldehydes. The decomposition treatment method for a thermosetting resin according to claim 1, wherein the addition amount is 0.05 to 20 parts by weight with respect to parts by weight. 3. The mononuclear phenolic compound is selected from phenol, cresol, xylenol, resorcin, and alkyl-substituted phenol.
A method for decomposing a thermosetting resin as described. 4. A low to medium molecular weight compound mainly composed of an oligomer having a molecular weight of 200 to 10,000 produced by decomposition treatment of a mononuclear phenol compound or a mixture of water and a mononuclear phenol compound. The method for decomposing a thermosetting resin according to any one of claims 1 to 3, which is obtained by separating and purifying the resin. 5. The thermosetting resin is a phenol resin, an epoxy resin, a polyimide resin, an unsaturated polyester resin,
The method for decomposing a thermosetting resin according to any one of claims 1 to 4, which is one kind or two or more kinds selected from a melamine resin and a urea resin. 6. A 200 obtained by decomposing a thermosetting resin by the decomposition treatment method according to claim 1.
A method for recycling a thermosetting resin, which comprises reusing a low to medium molecular weight compound mainly composed of an oligomer having a molecular weight of 10,000 to a raw material for the thermosetting resin.