JP2024035204A - Production method of recycled resin and production method of recycled polyolefin resin from mixture or laminate of different kinds of resins - Google Patents

Abstract

To decompose a resin material containing one or mores selected from a polyester resin and a polyamide resin and a polyolefin resin by high temperature/high pressure water or water in a subcritical state, and thereby take out a recycled polyolefin resin as a resin.SOLUTION: There is provided a production method of a recycled resin from a resin material containing two or more kinds of resins, in which the resin material contains one or more kinds selected from a polyester resin and a polyamide resin, and a polyolefin resin, wherein the method includes: a decomposition step of decomposing the polyester resin or the polyamide resin by high temperature/high pressure water or water in a subcritical state; and a separation step of separating the decomposed product into an undecomposed product containing the polyolefin resin and the decomposed product.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a recycled polyolefin resin, which comprises a step of decomposing a resin material containing one or more selected from polyester resins and polyamide resins and a polyolefin resin with high-temperature and high-pressure water or subcritical water. .

Material recycling is performed by collecting and remolding single resin materials, such as bottles made of polyethylene terephthalate (PET).
However, it is difficult to collect all of the various resin materials by type and perform material recycling. Furthermore, because it is difficult to achieve the desired performance using only a single resin, composite resin materials that are made by laminating or mixing multiple types of resin are also often used. Currently, these resin materials are disposed of in landfills or thermally recycled by recovering them as heat.

Therefore, it has been proposed to decompose resin materials with dilute nitric acid or alcohol in a supercritical state to decompose them into monomers and oligomers, and to chemically recycle them (for example, Patent Documents 1 and 2).
It has also been proposed to treat a laminate of a condensation polymer resin film and an addition polymer resin film with high-temperature, high-pressure water to decompose the condensation polymer resin into monomer components and convert the addition polymer resin into oil. (For example, claims 1 and 2 of Patent Document 3 and paragraph [0016] of the specification).

Japanese Patent Application Publication No. 10-237215 Japanese Patent Application Publication No. 2009-126913 Japanese Patent Application Publication No. 11-323006

When decomposed into monomers or oligomers through chemical recycling, resin can be obtained again by purifying the decomposed products and repolymerizing the monomers. However, purification and repolymerization require a lot of energy.

Therefore, the present invention decomposes a resin material containing one or more selected from polyester resins and polyamide resins and polyolefin resin with high temperature and high pressure water or water in a subcritical state, thereby converting recycled polyolefin resin into resin. The challenge is to extract it as

The present invention solves the above problems by having the following configuration.
A first aspect is a method for producing recycled resin from a resin material containing two or more types of resin, wherein the resin material contains one or more types selected from polyester resins and polyamide resins and a polyolefin resin. a decomposition step of decomposing the polyester resin or polyamide resin with high-temperature, high-pressure water or water in a subcritical state; a separation step of separating the polyolefin resin into an undecomposed product and a decomposed product; and the polyolefin resin. This is a method for producing a recycled polyolefin resin, comprising a recovery step of recovering an undecomposed product containing the above as a recycled polyolefin resin, and recovering the decomposed product as a raw material for the recycled resin.
A second aspect is a method for producing a recycled polyolefin resin according to the first aspect, wherein the resin material contains a polyester resin, a polyamide resin, and a polyolefin resin.
In a third aspect, in the first aspect or the second aspect, the decomposition step is a first decomposition step in which the polyamide resin is mainly decomposed with water at a temperature and pressure at which it decomposes, or with water in a subcritical state. , and a second decomposition step in which the polyester resin is decomposed with water at a temperature and pressure at which it decomposes, or water in a subcritical state.
In a fourth aspect, in the third aspect, between the first decomposition step and the second decomposition step, there is a separation step of separating into an undecomposed product and a decomposed product containing a polyolefin resin and a polyester resin. and a recovery step of recovering a decomposed product derived from a polyamide resin used as a raw material for the recycled resin.
A fifth aspect is a recycled polyolefin resin according to the fourth aspect, in which a decomposed product derived from a polyester resin used as a raw material for recycled polyester resin and a decomposed product derived from a polyamide resin used as a raw material for recycled polyamide resin are separately recovered. This is a manufacturing method.
A sixth aspect is that in any one of the first to fifth aspects, the polyester resin and the polyamide resin do not decompose (other than water in a subcritical state and water in a supercritical state) before the decomposition step. The method for producing recycled polyolefin resin includes a washing step of washing the resin material with high-temperature, high-pressure water.

A seventh aspect is a method for producing recycled polyolefin resin according to the sixth aspect, which includes a crushing step of reducing the size of the resin material before or after the washing step.
In an eighth aspect, in the aspect of any one of the first to seventh aspects, the resin material contains a multilayer structure resin material, and the polyolefin resin layer in the multilayer structure is a recycled material containing no resin other than the polyolefin resin. This is a method for producing polyolefin resin.
A ninth aspect is a method for producing recycled polyolefin resin pellets, which comprises pelletizing the recycled polyolefin resin obtained in any one of the first to eighth aspects.
A tenth aspect is a method for producing a recycled polyolefin resin film, which comprises forming the recycled polyolefin resin obtained in any one of the first to eighth aspects or the recycled polyolefin resin pellets obtained in the ninth aspect into a film. It is.

An eleventh aspect is a method for producing a polyolefin resin film, in which the recycled polyolefin resin obtained in any one of the first to eighth aspects is kneaded with another polyolefin resin and formed into a film.
A twelfth aspect is a method for producing a polyolefin resin film, in which the recycled polyolefin resin pellets obtained in the ninth aspect are kneaded with other polyolefin resin pellets and formed into a film.
A thirteenth aspect is the method for producing a recycled polyolefin resin according to any one of the first to eighth aspects, wherein the resin material contains a metal.
A fourteenth aspect is the method for producing recycled polyolefin resin pellets according to the ninth aspect, wherein the resin material contains metal.

A 15th aspect is selected from the 1st to 8th aspects and the 13th aspect, which includes a cleaning step using an acid for cleaning the undecomposed substances with an acidic liquid, separately from the cleaning step of the sixth aspect. This is a method for producing a recycled polyolefin resin according to aspect 1.
A 16th aspect is one selected from the 9th aspect and the 14th aspect, which includes a cleaning step using an acid for cleaning the undecomposed substances with an acidic liquid, separately from the cleaning step of the sixth aspect. This is a method for producing recycled polyolefin resin pellets according to the embodiment.
A seventeenth aspect is a recycled polyolefin resin film according to any one of the eleventh and twelfth aspects, which includes a cleaning step using an acid for cleaning the undecomposed material with an acidic liquid, separately from the cleaning step of the sixth aspect. This is a manufacturing method.
The 18th aspect is a method for producing a recycled resin, in which monomers and oligomers obtained by purifying the decomposition products obtained in the first to eighth aspects are repolymerized.

According to the present invention, a resin material containing one or more selected from polyester resins and polyamide resins and a polyolefin resin is treated with high-temperature, high-pressure water or subcritical water to decompose the polyester resin or polyamide resin. By doing so, the recycled polyolefin resin can be taken out as a resin, and the decomposed product can be taken out as a raw material for the recycled resin. As a result, at least the polyolefin resin can be materially recycled while chemically recycling resins other than the polyolefin resin, so it is possible to save energy required for purification and repolymerization of monomers and the like.

FIG. 1 is a diagram showing one embodiment of the method for producing recycled polyolefin resin of the present invention. FIG. 1 is a diagram showing one embodiment of the method for producing recycled polyolefin resin of the present invention. 3 is a graph showing the results of Example 1. 3 is a graph showing the results of Example 2. 3 is a graph showing the results of Example 3.

The present invention is a method for producing recycled resin from a resin material containing two or more types of resin.

(resin material)
In the present invention, the resin material containing two or more types of resins is not particularly limited as long as it contains one or more types selected from polyester resins and polyamide resins and a polyolefin resin, but for example, polyester resin and a polyolefin resin, a laminate containing a polyester resin and a polyolefin resin, a resin composition containing a polyester resin and a polyolefin resin, a mixture containing a polyamide resin and a polyolefin resin, a polyamide resin and a polyolefin A laminate containing a resin, a resin composition containing a polyamide resin and a polyolefin resin, a mixture containing a polyester resin, a polyamide resin, and a polyolefin resin, a laminate containing a polyester resin, a polyamide resin, and a polyolefin resin, Examples include resin compositions containing polyester resins, polyamide resins, and polyolefin resins.
The resin material containing two or more types of resins may contain resins other than polyester resin, polyamide resin, and polyolefin resin, and may also contain organic compounds, metals, and inorganic compounds in addition to resins. good.

The polyester resin is not particularly limited, but includes, for example, polyethylene terephthalate resin (PET), polyethylene naphthalate resin (PEN), polybutylene terephthalate resin (PBT), polylactic acid (PLA), polyhydroxyalkanoate (PHA), and Copolymers and modified resins of these may be mentioned.

The polyamide resin is not particularly limited, but includes, for example, polyamide 6 (PA6) obtained from ε-caprolactam, polyamide 11 (PA11) obtained from 11-undecanelactam, etc., and polyamide 11 (PA11) obtained from hexamethylene diamine and adipic acid. Polyamide 6,6 (PA6,6), polyamide 6,10 (PA6,10) obtained from hexamethylene diamine and sebacic acid, etc., polyamide 10,10 (PA10, obtained from 1,10-decanediamine and sebacic acid, etc.) 10) and polyamide 9T (PA9T) obtained from 1,9-nonanediamine and terephthalic acid.

The polyolefin resin is not particularly limited, but includes, for example, polyethylene resin (PE), polypropylene resin (PP), ethylene-propylene copolymer resin (EPR), polystyrene resin (PS), ethylene-styrene copolymer resin, etc. can be mentioned.
Examples of the polyethylene resin (PE) include ultra-high density polyethylene resin (UDPE), high-density polyethylene resin (HDPE), medium-density polyethylene resin (MDPE), low-density polyethylene resin (LDPE), and linear low-density polyethylene resin. (LLDPE), etc.
Examples of the polypropylene resin (PP) include random polypropylene resin and block polypropylene resin.

Examples of the organic compound include, but are not particularly limited to, heat stabilizers, light stabilizers, plasticizers, ultraviolet absorbers, antioxidants, thickeners, dyes, etc. used in resin molded products.

The metal is not particularly limited, but examples of metals used together with the resin include aluminum, copper, tin, and lead.
Examples of the resin material include a laminate having an aluminum layer or a copper layer, a resin to which solder is attached, and the like.

Examples of the inorganic compound include inorganic fillers used in resin molded products, antioxidants, heat stabilizers, pigments, and the like.

In particular, soft packaging materials such as pouches used for refill containers, retort food containers, etc. are often multilayer resin materials having a polyolefin resin layer, a polyamide resin layer, a polyester resin layer, and an aluminum layer. Therefore, the method for producing recycled polyolefin resin of the present invention is particularly useful for producing recycled polyolefin resin from resin materials containing flexible packaging materials such as pouches.
When the resin material contains a multilayer structure resin material, the polyolefin resin layer in the multilayer structure may be a resin layer that does not contain any resin other than the polyolefin resin.

(Washing process)
The method for producing recycled polyolefin resin of the present invention may include a cleaning step when the resin material is dirty.
The washing step is a step before the decomposition step described below, and is a step of washing the resin material with high-temperature, high-pressure water that does not decompose the polyester resin and polyamide resin. The cleaning step is preferably carried out using high-temperature, high-pressure water other than subcritical water and supercritical water, for example, water at a temperature of 30 to 100°C and a pressure of 0.1 to 5 MPa (subcritical water). Water (other than water and water in a supercritical state) can be used. The water may contain not only pure water but also additives.
The additives are not particularly limited, and include, for example, organic compounds and inorganic compounds. Examples of the organic compound include alcohol and organic solvents. Examples of the inorganic compound include inorganic acids and inorganic compounds that dissolve in water and exhibit alkalinity.
The step of separating the eluted dirt components from the reaction system through the washing step may be performed at room temperature or at high temperature. Further, the step of separating the components of the dirt may be performed under normal pressure, reduced pressure, or high pressure.
The step of separating the dirt components may be carried out by any method as long as the dirt components can be discharged from the reaction system. Can be mentioned.
The washing step may be performed in a decomposition tank in which a decomposition step described below is performed.

(Decomposition process)
The method for producing recycled polyolefin resin of the present invention includes a decomposition step.
The decomposition step is performed using high temperature, high pressure water or subcritical water. Here, the high temperature and high pressure water refers to high temperature and high pressure water other than water in a subcritical state and water in a supercritical state, and the high temperature and high pressure water or water in a subcritical state refers to water in a supercritical state. High-temperature and high-pressure water other than that of
The water may contain not only pure water but also additives.
The additives are not particularly limited, and include, for example, organic compounds and inorganic compounds. Examples of the organic compound include alcohol and organic solvents. Examples of the inorganic compound include inorganic acids and inorganic compounds that dissolve in water and exhibit alkalinity.

The decomposition step is a step of decomposing polyester resin, polyamide resin, etc. in the resin material.
The temperature of the water in the decomposition step is not particularly limited, but from the viewpoint of suppressing deterioration of the recycled polyolefin resin, it is preferably 400°C or lower, more preferably 300°C or lower, and particularly preferably 270°C or lower. Further, the temperature of water in the decomposition step is not particularly limited, but from the viewpoint of improving the productivity of recycled polyolefin resin, it is preferably 80°C or higher, more preferably 100°C or higher, and particularly preferably 230°C or higher.
The water pressure in the decomposition step is preferably 0.5 MPa or more, more preferably 1 MPa or more, particularly preferably 5 MPa or more, from the viewpoint of improving the productivity of recycled polyolefin resin.
When the resin material contains a polyester resin and a polyamide resin, a first decomposition step using water at a temperature and pressure that mainly decomposes the polyamide resin, or water in a subcritical state, and a temperature that mainly decomposes the polyester resin. and a second decomposition step using pressure water or subcritical water.
The first decomposition step may be performed at a temperature and pressure that can decompose the polyamide resin, and the second decomposition step may be performed at a temperature and pressure that can decompose the polyester resin. In the first decomposition step, after raising the temperature, it is preferable to maintain a temperature range in which the polyamide resin can be decomposed for a certain period of time. In the second decomposition step, after the temperature is further increased from the first decomposition step, it is preferable to maintain a temperature range in which the polyester resin can be decomposed for a certain period of time. In this case, the temperature at which the polyester resin is mainly decomposed is in a higher temperature range than the temperature at which the polyamide resin is mainly decomposed.

(separation process)
The method for producing recycled polyolefin resin of the present invention includes a separation step.
The separation step is a step of separating the decomposed products decomposed in the decomposition step from the undecomposed products. The undecomposed product contains polyolefin resin. Since polyolefin resin is difficult to decompose, it is mainly included in undecomposed substances.
In the present invention, the undecomposed product does not refer to a product that has not been decomposed at all, but refers to aggregates in the liquid extracted from the decomposition process at a temperature of 25° C. and a pressure of 1013 hPa. Therefore, the recycled polyolefin resin may have a lower molecular weight than the polyolefin resin in the raw material, and may partially contain decomposed products (monomers and oligomers of polyester resins and polyamide resins). The decomposition products include monomers and oligomers of polyester resins and polyamide resins. The proportion of polyolefin resin contained in the undecomposed material is, for example, 50% by weight or more, 90% by weight or more, 99% by weight or more, etc., based on the total amount of the undecomposed material obtained in the separation step excluding water as 100% by weight. Can be mentioned. The proportion of monomers and oligomers of polyester resins and polyamide resins contained in the decomposition product is, for example, 50% by weight or more, 90% by weight or more, 99% by weight or more, assuming that the total amount of the decomposed product obtained in the separation step excluding water is 100% by weight. Examples include weight% or more.
When the decomposition step is divided into a plurality of steps, such as a first decomposition step and a second decomposition step, it is preferable to provide a separation step after each decomposition step. This facilitates purification of the decomposed product, and it becomes easy to separate and extract monomers, oligomers, etc. of polyester resins and polyamide resins from the decomposed product.

The separation step may be performed at room temperature or at high temperature. Further, the separation step may be performed under normal pressure, reduced pressure, or high pressure. The separation step provided between the plurality of decomposition steps is preferably performed at high temperature or high pressure, or under high temperature and high pressure, since energy loss is small.

The separation step may be performed by any method as long as the undecomposed product and the decomposed product can be separated, and examples include a method of extracting the decomposed product through a filter such as a sintered body. When the separation step is a solid-liquid separation step such as filtration, the aggregate (solid) may be an undecomposed product, and the fluid (liquid) may be a decomposed product.

(Collection process)
The method for producing recycled polyolefin resin of the present invention includes a recovery step of recovering decomposed products.
The recovered decomposition products are used as raw materials for recycled resin.
The decomposed product can be purified by filtration, fractional distillation, distillation, etc. and used as a raw material for recycled resin.
When the decomposition step is divided into multiple steps such as a first decomposition step and a second decomposition step, or when a separation step is provided after each decomposition step, after each decomposition step or each separation step, the decomposed product after each step is A recovery step may also be provided. For example, a first decomposition product recovery step is provided after the first decomposition step to recover decomposition products derived from polyamide resin, and a second decomposition product collection step is provided after the second decomposition step to collect decomposition products derived from polyester resin. Good too.

(Crushing process)
The method for producing recycled polyolefin resin of the present invention may include a crushing step.
The crushing step is a step of reducing the size of the resin material in order to make it easier to decompose in the decomposition step.
The crushing method in the crushing step is not particularly limited, and examples thereof include methods using a press machine, a rotary blade, a ball mill, etc., and these may be used alone or in combination of multiple types. Good too.

(Cleaning process using acidic liquid)
The method for producing recycled polyolefin resin of the present invention may include a step of washing undecomposed substances using an acidic liquid.
By including the cleaning step using the acidic liquid, metal foils such as aluminum and copper, inorganic additives, pigments, and the like in undecomposed substances can be removed.
In the cleaning step with an acidic liquid, cleaning can be performed with an acidic liquid at an appropriate temperature such as room temperature or high temperature, and cleaning can also be performed under normal pressure, reduced pressure, or high pressure.
The acidic liquid is not particularly limited, and for example, inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, organic acids such as formic acid and acetic acid, and mixtures thereof, acidic liquids diluted with water, etc. can be used.
The washing step using the acidic liquid is preferably performed after the decomposition step, and may be performed after the undecomposed substances are separated in the separation step.

(Cleaning process using alkaline liquid)
The method for producing recycled polyolefin resin of the present invention may include a step of washing undecomposed substances using an alkaline liquid.
By including the washing step using the alkaline liquid, oil, inorganic substances, pigments, and the like in the undecomposed substances can be removed.
In the alkaline liquid washing step, washing can be performed with an alkaline liquid at an appropriate temperature such as normal temperature or high temperature, and washing can also be performed under normal pressure, reduced pressure, or high pressure.
The alkaline liquid is not particularly limited, and for example, a solution of an alkaline substance can be used. Examples of the alkaline substances include sodium hydroxide, alkali metal hydroxides such as potassium hydroxide, alkaline earth metal hydroxides, alkali metal bicarbonates, and alkaline earth metal carbonates. .
The washing step using the alkaline liquid is preferably carried out after the decomposition step, and may be carried out after the undecomposed substances are separated in the separation step.

The method for producing recycled polyolefin resin of the present invention may have either one of the washing step using the acidic liquid and the washing step using the alkaline liquid, or may have both. You can leave it there.
When the method for producing the recycled polyolefin resin of the present invention includes both the washing step using the acidic liquid and the washing step using the alkaline liquid, the method may be performed using a neutral or It is preferable to provide a step of washing with a liquid having a pH near normal pH, a pH buffer solution, etc. between the washing step using the acidic liquid and the washing step using the alkaline liquid.

(Manufacture of pellets and films)
The recycled polyolefin resin obtained by the method for producing recycled polyolefin resin of the present invention can be processed into recycled polyolefin resin pellets using an extruder and a pelletizer.
At this time, it is also possible to mix virgin polyolefin resin or the like in addition to the recycled polyolefin resin.
Moreover, a recycled polyolefin resin film can be manufactured by using the recycled polyolefin resin or the recycled polyolefin resin pellets using an extrusion molding machine, an inflation molding machine, or the like.
At this time, a polyolefin resin film can be manufactured by mixing virgin polyolefin resin or polyolefin resin pellets in addition to the recycled polyolefin resin or recycled polyolefin resin pellets.

(Production of recycled resin by repolymerization)
By refining the decomposed product obtained in the recovery step, adding a polymerization catalyst, etc., and repolymerizing it, a recycled polyester resin or a recycled polyamide resin can be produced.

(Preferred embodiment)
Hereinafter, preferred embodiments will be described using the drawings.

In FIG. 1, water is introduced from a water introduction pipe 101, and after being pressurized by a pump 102, is introduced into a temperature rising pipe 103, becomes high temperature and high pressure water, and is introduced into a decomposition tank 106.
Further, the resin material is introduced into the decomposition tank 106 through the resin material introduction pipe 104.
In the decomposition tank 106, the high temperature and high pressure water is further heated in the temperature raising region 105 to become subcritical water or high temperature and high pressure water close to the subcritical state, which removes dirt from the resin material. Washing or decomposing the polyester resin portion, polyamide resin portion, etc. of the resin material into monomers and oligomers.

After the dirt components have been eluted in the decomposition tank 106 or the resin material 107 has been sufficiently decomposed, the back pressure valve 1091 is opened, and the decomposed products and subcritical The water in the decomposed state and the high temperature and high pressure water close to the subcritical state are extracted to the oil-water separation tank 110 through the decomposition product extraction pipe 109 while maintaining the pressure in the decomposition tank.
That is, dirt components and decomposed products of polyester resin and polyamide resin can be removed at once. Further, if necessary, cleaning of dirt components, decomposition of polyester resin, and decomposition of polyamide resin can be performed separately. Specifically, cleaning is performed using water at a temperature and pressure that allows cleaning of dirt components, and the dirt components and decomposed products are extracted, and then decomposition is performed at a temperature and pressure that allows the polyamide resin to be decomposed. It is also possible to extract each component separately by extracting the polyamide resin decomposition product, and further decomposing the polyester resin at a temperature and pressure that allows decomposition of the polyester resin to extract the polyester resin decomposition product.

In the oil-water separation tank 110, at least the high-temperature and high-pressure water or subcritical water in the decomposition tank 106 is cooled to such an extent that it becomes liquid water. As a result, the decomposed product extracted into the oil-water separation tank 110 is separated into an oil phase consisting of monomers and oligomers of polyester resin or polyamide resin, and an aqueous phase. The liquid extracted into the oil-water separation tank 110 may be lowered not only in temperature but also in pressure.

The decomposed product is separated into an oil phase and an aqueous phase in the oil-water separation tank 110. The aqueous phase is extracted into a water circulation path 112 and returned to the pump 102, and the oil phase is extracted from an oil phase extraction pipe 111.
It is preferable to keep the water circulation path 112 warm because it reduces energy loss.
The polyolefin resin, which is difficult to decompose even in subcritical water, is extracted from the recycled polyolefin resin extraction pipe 108 as recycled polyolefin resin.
The recycled polyolefin resin may be washed as appropriate and used for producing recycled polyolefin resin pellets, used for producing recycled polyolefin resin films, or kneaded with virgin polyolefin resin and used for producing polyolefin resin films. can do.
In the embodiment shown in FIG. 1, recovery of decomposed products depending on the situation and production of recycled polyolefin resin can be performed using a small number of pressure-resistant containers.

Using Figure 2, we will explain how a decomposed product of polyester resin, a decomposed product of polyamide resin, and recycled polyolefin resin are separately recovered from a resin material that is a laminate of polyester resin, polyamide resin, and polyolefin resin. do.
Water is introduced from a water introduction pipe 201, and after being pressurized by a pump 202, is introduced into a temperature rising pipe 203, becomes high temperature and high pressure water, and is introduced into a decomposition tank 206.
Further, the resin material is introduced into the decomposition tank 206 through the resin material introduction pipe 204.

In the decomposition tank 206, the high temperature and high pressure water is further heated in a first temperature increasing region 205a to become high temperature and high pressure water, which decomposes and dissolves dirt and the like attached to the resin material. By opening the back pressure valve 2091a once at this stage, dirt, etc. and high-temperature, high-pressure water are extracted into the first oil-water separation tank 210a through the first decomposition product extraction pipe 209a through a sintered filter (not shown). Served.
In the first oil-water separation tank 210a, the temperature is lowered as necessary, and the oil is separated into an oil phase containing dirt and the like and an aqueous phase. The liquid extracted into the first oil-water separation tank 210a may be reduced in temperature as well as in pressure.
The water phase separated in the first oil-water separation tank 210a is extracted to the water circulation path 212 and returned to the pump 202, and the oil phase is extracted from the first oil phase extraction pipe 211a.
It is preferable to keep the water circulation path 212 warm because it reduces energy loss.

In the decomposition tank 206, as the resin material 207 approaches the recycled polyolefin resin extraction pipe 208, the temperature inside the decomposition tank 206 changes to the first temperature increase area 205a, the second temperature increase area 205b, and the third temperature increase area 205c. is starting to rise.

In the second temperature increasing region 205b, the temperature and pressure are adjusted so that mainly the polyamide resin in the resin material 207 is decomposed.
Therefore, in the decomposition tank 206 in the second temperature increasing region 205b, the polyamide resin is mainly decomposed, and monomers and oligomers derived from the polyamide resin are obtained as decomposition products. In addition, by opening the back pressure valve 2091b, decomposition products containing monomers and oligomers derived from polyamide resin pass through a sintered filter (not shown), and pass through the second decomposition product extraction pipe 209b to the second oil-water separation tank 210b. being extracted.

The water in the second oil-water separation tank 210b is cooled at least lower than the water in the decomposition tank 206, and is separated into an oil phase containing monomers and oligomers derived from the polyamide resin and an aqueous phase. The liquid extracted into the second oil-water separation tank 210b may be reduced in temperature as well as in pressure.
The aqueous phase separated in the second oil-water separation tank 210b is extracted into the water circulation path 212 and returned to the pump 202, and the oil phase is extracted from the second oil phase extraction pipe 211b, purified, and recycled into recycled resin. Becomes raw material.

In the third temperature increasing region 205c, the temperature and pressure are adjusted so that mainly the polyester resin in the resin material 207 is decomposed.
Therefore, in the decomposition tank 206 in the third temperature increasing region 205c, the polyester resin is mainly decomposed, and monomers and oligomers derived from the polyester resin are obtained as decomposed products. In addition, by opening the back pressure valve 2091c, decomposition products containing monomers and oligomers derived from polyester resin pass through a sintered filter (not shown), and pass through the third decomposition product extraction pipe 209c to the third oil-water separation tank 210c. being extracted.

The water in the third oil-water separation tank 210c has a temperature lower than that of the water in the decomposition tank 206, and is separated into an oil phase containing monomers and oligomers derived from polyester resin, and an aqueous phase. The liquid extracted into the third oil-water separation tank 210c may be lowered in temperature as well as lowered in pressure.
The aqueous phase separated in the third oil-water separation tank 210c is extracted into the water circulation path 212 and returned to the pump 202, and the oil phase is extracted from the third oil phase extraction pipe 211c and purified to produce recycled resin. Becomes raw material.
In the embodiment shown in FIG. 2, for example, dirt components, polyester resin decomposition products, and polyamide resin decomposition products can be collected separately, so purification of polyester resin decomposition products and polyamide resin decomposition products is easy, and polyester resin and polyamide resin decomposition products can be easily purified. It is advantageous for producing recycled resins by repolymerizing polyamide resins.

The polyolefin resin, which is difficult to decompose even in subcritical water, is extracted from the recycled polyolefin resin extraction pipe 208 as recycled polyolefin resin.
The recycled polyolefin resin may be washed as appropriate and used for producing recycled polyolefin resin pellets, used for producing recycled polyolefin resin films, or kneaded with virgin polyolefin resin and used for producing polyolefin resin films. can do.

Although the present invention has been described above based on the preferred embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. Modifications include additions, substitutions, omissions, and other changes to components in each embodiment.

(Example 1)
An example of processing a laminate of different resins using the apparatus shown in FIG. 1 is shown.
As a laminate of different resins, a laminate consisting of polyethylene (68.9 wt%), polyethylene terephthalate with an aluminum vapor deposited layer (12.6 wt%), nylon 6 (12.6 wt%), adhesive layer, etc. (5.9 wt%) was prepared, cut into small pieces of 2 to 3 mm square, and 0.1 g of the pieces were introduced into the decomposition tank 106.
While adjusting the pump 102 so that the pressure of the high-temperature, high-pressure water introduced into the decomposition tank is 10 MPa, decomposed products and high-temperature, high-pressure water are continuously extracted from the back pressure valve 1091 at a flow rate of 0.5 g/min. Ta.
At this time, the temperature in the temperature increasing region 105 is raised to 100°C at a rate of 5°C/min (first stage temperature raising process), held at 100°C for 30 minutes, and then again at a rate of 5°C/min. The temperature was raised to 300°C (second stage heating process) and held at 300°C for 30 minutes.
The extracted decomposition products were analyzed by liquid chromatography mass spectrometry, and 21 types of decomposition products derived from nylon 6 and 25 types of decomposition products derived from polyethylene terephthalate were identified, and semi-quantitative analysis was performed based on the peak area.
FIG. 3 shows the results of semi-quantitative analysis using the decomposition products continuously extracted from the back pressure valve 1091. The total value of the peak area values of the decomposition products derived from nylon 6 and the total value of the peak area values of the decomposition products of polyethylene terephthalate are shown as light gray bar graphs and dark gray bar graphs, respectively.

The decomposition products derived from nylon 6 increased during the first temperature raising process and reached a maximum value at 100°C. After that, when the temperature was maintained at 100° C. for 30 minutes, the amount of decomposition products (peak area) derived from nylon 6 gradually and exponentially decreased. After 30 minutes of holding at 100°C, the temperature started to rise again, and at the same time, the generation of decomposed products derived from nylon 6 resumed, reaching a maximum value around 275°C. Furthermore, the decomposition products derived from polyethylene terephthalate reached a maximum value at the same temperature, and decreased after reaching 300°C.
After the reaction was completed, the recovered solid content was analyzed by infrared spectroscopy and was confirmed to be polyethylene.
Therefore, while the temperature was maintained at 100° C., only the decomposition products derived from nylon 6 could be individually recovered, and polyethylene could be recovered from the solids after the reaction was completed.

(Example 2)
The temperature of the temperature increasing region 105 was raised to 150°C at a rate of 5°C/min, held at 150°C for 30 minutes, and then raised again to 300°C at a rate of 5°C/min. The test was carried out under the same conditions as in Example 1 except that the test was held for 30 minutes.

The amount of decomposed products derived from nylon 6 (peak area in liquid chromatography) reached a maximum value at 125°C, and a small amount of decomposed products derived from nylon 6 were produced even while the temperature was maintained at 150°C. When the temperature increase was restarted, decomposition products derived from nylon 6 were generated again. Further, the amount of produced decomposition products derived from nylon 6 and polyethylene terephthalate (peak area in liquid chromatography) reached a maximum value at 275°C. After reaching 300°C, all decomposition products decreased exponentially.
After the reaction was completed, the recovered solid content was analyzed by infrared spectroscopy and was confirmed to be polyethylene.
Therefore, while the temperature was maintained at 150° C., only the decomposition products derived from nylon 6 could be individually recovered, and polyethylene could be recovered from the solids after the reaction was completed.
The results are shown in Figure 4. The total value of the peak area values of the decomposition products derived from nylon 6 and the total value of the peak area values of the decomposition products of polyethylene terephthalate are shown as light gray bar graphs and dark gray bar graphs, respectively.

(Example 3)
The temperature of the temperature increasing region 105 was raised to 250°C at a rate of 5°C/min, held at 250°C for 90 minutes, and then raised again to 300°C at a rate of 5°C/min. The test was carried out under the same conditions as in Example 1 except that the test was held for 30 minutes.
The amount of decomposed products derived from nylon 6 (peak area in liquid chromatography) reaches a maximum value at 100°C, and the amount of decomposed products derived from nylon 6 and polyethylene terephthalate (peak area in liquid chromatography) reaches a maximum value at 100°C. After the peak area) reached its maximum value at 250°C, the amount of product decreased exponentially. After the temperature was maintained at 250°C, no decomposition product peak was observed even when the temperature was raised again.
From this, it was found that the hydrolysis reaction of the laminated product was completely completed at 250°C.
After the reaction was completed, the recovered solid content was analyzed by infrared spectroscopy and was confirmed to be polyethylene. From this, it was confirmed that polyethylene could be recovered from laminated products by subcritical water treatment at 250°C.
The results are shown in Figure 5. The total value of the peak area values of the decomposition products derived from nylon 6 and the total value of the peak area values of the decomposition products of polyethylene terephthalate are shown as light gray bar graphs and dark gray bar graphs, respectively.

DESCRIPTION OF SYMBOLS 101... Water introduction pipe, 102... Pump, 103... Temperature rising pipe, 104... Resin material introduction pipe, 1041... Valve, 105... Temperature rising area, 106... Decomposition tank, 107... Resin material, 108... Recycled polyolefin resin extraction pipe , 1081...Valve, 109...Decomposed product extraction pipe, 1091...Back pressure valve, 110...Oil/water separation tank, 111...Oil phase extraction pipe, 1111...Valve, 112...Water circulation path, 113...Sintered compact filter, 201...Water introduction Pipe, 202... Pump, 203... Temperature increasing tube, 204... Resin material introduction tube, 2041... Valve, 205a... First temperature increasing area, 205b... Second temperature increasing area, 205c... Third temperature increasing area, 206... Decomposition Tank, 207... Resin material, 208... Recycled polyolefin resin extraction pipe, 2081... Valve, 209a... First decomposition product extraction pipe, 2091a... Back pressure valve, 209b... Second decomposition product extraction pipe, 2091b... Back pressure valve, 209c... 3 Degradation product extraction pipe, 2091c...back pressure valve, 210a...first oil/water separation tank, 210b...second oil/water separation tank, 210c...third oil/water separation tank, 211a...first oil phase extraction pipe, 2111a...valve, 211b... Second oil phase extraction pipe, 2111b...Valve, 211c...Third oil phase extraction pipe, 2111c...Valve, 212...Water circulation path

Claims (14)

A method for producing recycled resin from a resin material containing two or more types of resin, the method comprising:
The resin material contains one or more selected from polyester resins and polyamide resins, and a polyolefin resin,
a decomposition step of decomposing the polyester resin or polyamide resin with high temperature, high pressure water or subcritical water;
a separation step of separating into an undecomposed product containing a polyolefin resin and a decomposed product;
A method for producing a recycled polyolefin resin, comprising a recovery step of recovering an undecomposed product containing the polyolefin resin as a recycled polyolefin resin, and recovering the decomposed product as a raw material for the recycled resin. The method for producing recycled polyolefin resin according to claim 1, wherein the resin material contains a polyester resin, a polyamide resin, and a polyolefin resin. The decomposition step is a first decomposition step in which the polyamide resin is decomposed with water at a temperature and pressure that decomposes, or with water in a subcritical state;
2. The method for producing a recycled polyolefin resin according to claim 1, further comprising a second decomposition step in which the polyester resin is decomposed with water at a temperature and pressure at which it decomposes, or with water in a subcritical state. Between the first decomposition step and the second decomposition step, a step of separating undecomposed products and decomposed products containing a polyolefin resin and a polyester resin;
4. The method for producing a recycled polyolefin resin according to claim 3, further comprising a recovery step of recovering a decomposed product derived from the polyamide resin used as a raw material for the recycled resin. 5. The method for producing a recycled polyolefin resin according to claim 4, wherein a decomposed product derived from a polyester resin used as a raw material for the recycled polyester resin and a decomposed product derived from a polyamide resin used as a raw material for the recycled polyamide resin are separately recovered. 2. The method for producing recycled polyolefin resin according to claim 1, further comprising, before the decomposition step, a washing step of washing the resin material with high-temperature, high-pressure water that does not decompose the polyester resin and polyamide resin. The method for producing recycled polyolefin resin according to claim 6, further comprising a crushing step of reducing the size of the resin material before or after the washing step. 2. The method for producing recycled polyolefin resin according to claim 1, wherein the resin material contains a multilayer structure resin material, and the polyolefin resin layer in the multilayer structure does not contain any resin other than the polyolefin resin. A method for producing recycled polyolefin resin pellets, which comprises pelletizing the recycled polyolefin resin obtained by the method for producing recycled polyolefin resin according to claim 1. A method for producing a recycled polyolefin resin film, which comprises forming a recycled polyolefin resin obtained by the method for producing a recycled polyolefin resin according to claim 1 into a film. A method for producing a polyolefin resin film, which comprises kneading the recycled polyolefin resin obtained by the method for producing recycled polyolefin resin according to claim 1 and another polyolefin resin, and forming the mixture into a film. The method for producing recycled polyolefin resin according to claim 1, wherein the resin material contains metal. The method for producing a recycled polyolefin resin according to claim 1, further comprising the step of washing the undecomposed material with an acidic liquid. A method for producing a recycled polyolefin resin, which comprises repolymerizing a monomer or oligomer obtained by purifying a decomposed product obtained by the method for producing a recycled polyolefin resin according to claim 1.

Images