Method for decomposing polymer material, method for producing recycled resin, and method for recovering inorganic filler

1. A method for decomposing a polymer material, comprising:

providing a polymer material containing a resin component composed of a first monomer which is a phenolic compound, and a second monomer which is an aldehyde compound;

providing a plurality of sample mixtures, each of which includes said polymer material and said first monomer or a derivative of said first monomer, and has a different second/first monomer ratio from each other, the second/first monomer ratio being a molar ratio of an amount of the second monomer to an amount of the first monomer and the derivative of said first monomer in a reaction system for decomposing said resin component;

decomposing chemically said resin component in the plurality of sample mixtures to obtain a plurality of sample chemical raw materials;

measuring an average molecular weight of each of the plurality of sample chemical raw materials;

acquiring data of a correlation between an average molecular weight of each of the plurality of sample chemical raw materials and a second/first monomer ratio in each of the plurality of sample mixtures which generates the each of the plurality of sample chemical raw materials;

determining a first range of the second/first monomer ratio in which when the second/first monomer ratio becomes small, the molecular weight of the chemical raw material becomes small;

determining a second range of the second/first monomer ratio which is smaller than and adjacent to the first range of the second/first monomer ratio, in which when the second/first monomer ratio becomes small, the molecular weight of the chemical raw material substantially does not change;

determining a threshold value as a boundary value between the first range of the second/first monomer ratio and the second range of the second/first monomer ratio;

determining a target average molecular weight of said chemical raw material;

determining an addition amount of said first monomer or the derivative of said first monomer to be added to said polymer material based on said data of the correlation so that said chemical raw material having the target average molecular weight is obtained by decomposing said resin component and so that the second/first monomer ratio is not less than the threshold value and less than 1.0;

mixing said first monomer and the derivative of said first monomer in said addition amount with said polymer material to provide a mixture of said polymer material and said first monomer and the derivative of said first monomer; and

decomposing chemically said resin component in the mixture to produce said chemical raw material.

2. The method for decomposing a polymer material according to claim 1 , in which the method further comprises making said first monomer or the derivative of said first monomer in said addition amount determined into a supercritical state or subcritical state, and said first monomer or the derivative of said first monomer in the mixture is made into a supercritical state or subcritical state.

3. The method for decomposing a polymer material according to claim 1 , in which said phenolic compound is one or more kinds selected from phenol, o-cresol, m-cresol and p-cresol.

4. The method for decomposing a polymer material according to claim 1 , in which said aldehyde compound is one or more kinds selected from formaldehyde, paraformaldehyde, trioxane and hexamethylenetetramine.

5. The method for decomposing a polymer material according to claim 1 , in which said polymer material contains a crosslinked polymer.

6. The method for decomposing a polymer material according to claim 5 , in which said crosslinked polymer is a phenol resin.

7. A method for decomposing a polymer material, comprising:

providing a polymer material containing a resin component composed of a first monomer which is a phenolic compound, and a second monomer which is an aldehyde compound;

providing a plurality of sample mixtures, each of which includes said polymer material and said first monomer or a derivative of said first monomer, and has a different second/first monomer ratio from each other, the second/first monomer ratio being a molar ratio of an amount of the second monomer to an amount of the first monomer and the derivative of said first monomer in a reaction system for decomposing said resin component;

decomposing chemically said resin component in the plurality of sample mixtures to obtain a plurality of sample chemical raw materials;

measuring an average molecular weight of each of the plurality of sample chemical raw materials;

acquiring data of a correlation between an average molecular weight of each of the plurality of sample chemical raw materials and a second/first monomer ratio in each of the plurality of sample mixtures which generates the each of the plurality of sample chemical raw materials;

determining a first range of the second/first monomer ratio in which when the second/first monomer ratio becomes small, the molecular weight of the chemical raw material becomes small;

determining a second range of the second/first monomer ratio which is smaller than and adjacent to the first range of the second/first monomer ratio, in which when the second/first monomer ratio becomes small, the molecular weight of the chemical raw material substantially does not change;

determining a threshold value as a boundary value between the first range of the second/first monomer ratio and the second range of the second/first monomer ratio;

determining an addition amount of said first monomer or the derivative of said first monomer to be added to said polymer material so that the second/first monomer ratio is approximately the threshold value;

mixing said first monomer and the derivative of said first monomer in said addition amount with said polymer material to provide a mixture of said polymer material and said first monomer and the derivative of said first monomer; and

decomposing chemically said resin component in the mixture to produce said chemical raw material.