JP2012219210A - Method for producing low-molecular polymer, low-molecular polymer obtained by the method, and coating material, powder coating material, adhesive, fiber and nonwoven fabric using the polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a low-molecular polymer, capable of easily obtaining a low-molecular polymer from a high-molecular polymer which is synthesized by condensation polymerization and has a bond of -C(=O)O- or -C(=O)N- in a straight chain of the molecule, and further obtaining a low-molecular polymer without a need of separating operation even in a product including a combination of high-molecular polymer and metal, and to provide a low-molecular polymer obtained by the method, and a coating material, a powder coating material, an adhesive, a fiber and a nonwoven fabric each using the low-molecular polymer.SOLUTION: The high-molecular polymer synthesized by condensation polymerization and having a bond of -C(=O)O- or -C(=O)N- in a straight chain of the molecule is brought into contact with water under high temperature and high pressure, whereby the bond of -C(=O)O- or -C(=O)N- is broken to reduce the molecular weight of the polymer to 90% or less of that before bond dissociation.

Description

  The present invention relates to a method for producing a low molecular weight polymer, a low molecular weight polymer obtained by the method, a coating material using the low molecular weight polymer, a powder coating material, an adhesive, a fiber and a nonwoven fabric.

  A high molecular polymer synthesized by condensation polymerization and having a bond of —C (═O) O— or —C (═O) N— in the linear chain of the molecule is a coating material for tires, sheets, pipe materials, electric wires and cables. And is used in a wide range of fields.

  However, in the case of a high molecular polymer having a bond of —C (═O) O— or —C (═O) N— on the linear chain of the molecule, for example, a high molecular polymer such as polyester or polyurethane, much after use is reclaimed. Either disposal or incineration was done.

  However, in the case of landfill, there is a problem that firstly it is difficult to secure a landfill site, and when the volume is reduced by pulverization or the like to increase the landfill efficiency, there is a problem that a large amount of cost is required for pulverization or the like.

  When incinerating high-molecular polymers after use, there is a problem that gases harmful to human bodies and the environment are generated during incineration, and the incinerator is damaged by the gases.

  Such high molecular weight polymers have also been studied for the purpose of recycling. For example, waste polyurethane foam is classified according to its density and pulverized into chips to obtain a regenerated molded product having a predetermined density. A recycling method has been proposed in which a waste chip is selected as a combination of two or more types of waste chips having different densities, a binder is applied to the combined chip, the mold is then filled and molded ( Patent Document 1).

  However, in order to obtain the above-mentioned recycled products, many steps such as waste material separation, pulverization, combination of waste material chips after pulverization, binder application, and molding are required, and the recycling cost is high, so it has not been put into practical use. Was the current situation.

  Also, when disposing of a combination of polymer and metal, such as electric wires, cables, tires, etc., it is necessary to separate the polymer part from the metal part. In other words, it was incinerated without separation, and only the remaining metal parts were reused.

JP 2005-238604 A

The present invention has been made in view of such technical problems, and is synthesized by condensation polymerization and has a bond of —C (═O) O— or —C (═O) N— in the linear chain of the molecule. A low-molecular polymer that can easily obtain a low-molecular polymer from a high-molecular polymer, and even a product that combines a high-molecular polymer and a metal can be obtained without requiring separation work. It is an object of the present invention to provide a production method, a low molecular polymer obtained by the method, a coating material, a powder coating material, an adhesive, a fiber and a nonwoven fabric using the low molecular polymer.

  In order to achieve the above object, the inventions of claims 1 to 7 are synthesized by polycondensation and have a high bond having a bond of —C (═O) O— or —C (═O) N— in the linear chain of the molecule. By contacting the molecular polymer with water under high temperature and high pressure, the —C (═O) O— or —C (═O) N— bond of the polymer is cleaved, and the molecular weight of the polymer is reduced before the bond is cleaved. The gist of the present invention is a method for producing a low molecular weight polymer, characterized by being 90% or less.

  The low molecular weight polymer obtained by the method according to claim 1 is synthesized by condensation polymerization, and has a high molecular weight having a —C (═O) O— or —C (═O) N— bond on the linear chain of the molecule. In the molecular polymer, the —C (═O) O— or —C (═O) N— bond is cleaved, and the molecular weight of the polymer is reduced to 90% or less before the bond breakage, for example, a monomer or oligomer level. Refers to a polymer that has been degraded to

  The invention according to claims 8 and 9 proposes a low molecular weight polymer obtained by the method for producing a low molecular weight polymer according to any one of claims 1 to 7, and the invention according to claims 10 to 13 proposes a low molecular weight polymer. The present invention proposes a paint, a powder paint, an adhesive, a fiber, and a nonwoven fabric characterized by using a polymer.

  According to the method for producing a low molecular weight polymer of the present invention, -C (= O) O- or -C (= O) is added to a linear chain of a used molecule by a simple treatment of contacting with water at high temperature and high pressure. It is possible to decompose a high molecular polymer having an N- bond to a level of 90% or less of a monomer or oligomer prior to bond cleavage. For this reason, large-scale processing equipment is not required, and the energy, labor, and cost required for the production of the low-molecular polymer can be greatly reduced. Further, since the method of the present invention does not use an organic solvent or a catalyst, it does not adversely affect the environment. Further, according to the method of the present invention, the used high molecular polymer can be decomposed to a level of 90% or less before bond breaking, and the obtained low molecular weight polymer can be used as it is or mixed with a crosslinking agent. It can be used as a raw material for regeneration polymerization. In addition, according to the method of the present invention, a low molecular weight polymer can be obtained without requiring a separation operation even when a product combining a high molecular weight polymer and a metal is regenerated. A washing step is also unnecessary.

  The method for producing a low molecular weight polymer of the present invention also proposes a novel method for adjusting an unused high molecular polymer to a molecular weight according to its use and required performance (property). That is, a high molecular polymer having a bond of —C (═O) O— or —C (═O) N— in a linear chain of an unused molecule is brought into contact with water under high temperature and high pressure, and By cleaving the bond of —C (═O) O— or —C (═O) N—, a low molecular polymer having a molecular weight corresponding to the required performance (property) of 90% or less before the bond cleavage is obtained. There is an advantage that it can be produced by a simple treatment of contacting with water in the absence of a catalyst and under high temperature and pressure.

The schematic diagram which showed the analysis procedure of the decomposition product of PET. The photograph which shows the change of the external appearance by the processing time of the process (200 degreeC, 1.6 MPa) made to contact with water under high temperature high pressure. The graph which shows the change of the particle size with the processing time of the process (200 degreeC, 1.6 MPa) made to contact with water under high temperature high pressure. The electron micrograph which shows the state of the decomposition product surface of PET. An electron micrograph showing the surface state of terephthalic acid. The graph which shows the change of TG curve by processing time. The graph which shows the change of the DSC curve by processing time (200 degreeC, 1.6 MPa). The schematic diagram which shows the crystal structure of PET. The graph which shows the change of the X-ray pattern of PET by the process made to contact with water under high temperature / high pressure. Graph showing changes in CP / MAS ¹³ C-NMR spectra by treatment of contacting with water at high temperature and high pressure. The graph which shows the measurement result of the molecular weight and molecular weight distribution by GPC. The graph which shows the < ¹ > H-NMR spectrum of untreated PET. The graph which shows the < ¹ > H-NMR spectrum of PET processed for 30 minutes. The graph which shows the < ¹ > H-NMR spectrum of PET processed for 60 minutes. The graph which shows the < ¹ > H-NMR spectrum of PET processed for 120 minutes. The graph which shows the < ¹ > H-NMR spectrum of PET processed for 180 minutes. The graph which shows the < ¹ > H-NMR spectrum of PET (liquid 2) processed for 240 minutes. The graph which shows the < ¹ > H-NMR spectrum of PET (liquid 2) processed for 30 minutes (225 degreeC). The graph which shows the < ¹ > H-NMR spectrum of PET (liquid 2) processed for 60 minutes (225 degreeC). The graph which shows the < ¹ > H-NMR spectrum of PET (liquid 2) processed for 120 minutes (225 degreeC). The graph which shows the < ¹ > H-NMR spectrum of the solid part (solid 2) of PET processed for 240 minutes. The graph which shows the number average molecular weight change by processing time and temperature. The graph which shows the ratio of the terephthalic acid (TPA) by processing time and temperature. The graph which shows the change of the hydroxyl value and acid value by processing time (200 degreeC). The graph which shows the change of the hydroxyl value and acid value by processing time (225 degreeC). The graph which shows the < ¹ > H-NMR spectrum of the liquid part (liquid 1) of PET processed for 240 minutes. The photograph which shows the change (200 degreeC, 1.6 MPa) of the PET bottle by processing time. The graph which compared the viscoelasticity (tan-delta) of the epoxy compound using the decomposition product of PET and PET.

  Hereinafter, a method for producing a low molecular weight polymer of the present invention (hereinafter simply referred to as a method), a low molecular weight polymer obtained by the method, a coating material using the low molecular weight polymer, a powder coating material, an adhesive, a fiber and a nonwoven fabric, explain in detail.

  The present invention relates to a polymer synthesized by condensation polymerization and having a polymer having a bond of -C (= O) O- or -C (= O) N- on the straight chain of the molecule, with 90% or less of the monomer before bond cleavage. It proposes a novel method for producing a low molecular weight polymer that can be decomposed to the level of oligomers.

The high molecular polymer to be treated by the method of the present invention is synthesized by condensation polymerization and has a bond of —C (═O) O— or —C (═O) N— in the linear chain of the molecule. Specifically, it has a chain or network structure composed of a polymer obtained by polymerizing one kind of monomer or a copolymer obtained by copolymerizing plural kinds of monomers, and -C ( ═O) O— or —C (═O) N— bond. More specifically, a polymer having one or more selected from the group consisting of esters, urethanes, ethers, imides, amides, ureas, and carbonates as the main bonds can be mentioned.

  The category of the high molecular polymer to be treated by the method of the present invention includes a crosslinked polymer or a composite of a high molecular polymer and a metal, such as a molded product of the high molecular polymer, an electric wire, a cable, and a tire. .

  Next, the contact of water with the high molecular polymer under high temperature and high pressure will be described. In the method of the present invention, the polymer is contacted with water under high temperature and high pressure, preferably at 100 ° C. or higher and 0.1 MPa or higher. Water becomes saturated water vapor and comes into contact with the polymer, and acts to break the —C (═O) O— or —C (═O) N— bond of the polymer. When the temperature and pressure at the time of contact are less than 100 ° C. and less than 0.1 MPa, not only the decomposition of the polymer does not proceed effectively, but also the treatment time becomes longer and the energy cost becomes higher.

  The conditions of temperature and pressure at the time of contact are more preferably 400 ° C. and 0.2 to 3.0 MPa. In this case, the action of cleaving the bond of —C (═O) O— or —C (═O) N— of the high molecular polymer proceeds more effectively, and the treatment time can be shortened. It has the merit that reduction can be achieved.

  In addition, the time for which the polymer is brought into contact with water under high temperature and high pressure is appropriately changed depending on the type of polymer, the volume of the polymer to be treated, and when the polymer is a molded product, depending on its size and shape. Good. Specifically, it is preferably 1 to 300 minutes, more preferably 30 to 250 minutes. If the contact time is less than 1 minute, contact between the polymer and water is insufficient, and the —C (═O) O— or —C (═O) N— bond of the polymer is not broken. Or, even if the bond is broken, the decomposition is insufficient. When the contact time exceeds 300 minutes, even if the contact time increases, the decomposition does not proceed any further, so that the processing itself is wasted.

  The method of the present invention is carried out by contacting the polymer with water at a high temperature and high pressure such as 100 ° C. or higher and 0.1 MPa or higher. Therefore, the reactor used is sufficiently resistant to such temperature and pressure. It is desirable that the polymer can be easily charged and discharged. Specifically, it is desirable that the flow of water (water vapor) becomes turbulent so that the polymer and water are sufficiently in contact in the reactor.

  In addition, as a method for supplying water (high pressure steam) to the reactor, for example, a method such as an autoclave for heating water in the reactor to increase the pressure, a forced circulation boiler, a vertical boiler, a furnace boiler, A method using a boiler such as a natural circulation boiler can be adopted.

  The low molecular weight polymer obtained by the method of the present invention is in the form of liquid, pasty, or granular depending on the type of polymer and conditions (temperature, pressure, contact time).

  The low molecular weight polymer obtained by the method of the present invention can be used as a raw material for regenerated polymerization as it is or by mixing with a crosslinking agent such as diisocyanate, bisurethane, diamine, dicarboxylic acid or dichloric acid derivative.

  In the molecule of the low molecular weight polymer obtained by the method of the present invention, there are reactive groups such as hydroxyl groups and amino groups. These reactive groups are used when the low molecular weight polymer is re-reacted as a regenerative polymerization raw material, or when the low molecular weight polymer and the cross-linking agent are reacted as a regenerative polymerization raw material with a mixture of cross-linking agents. It has a function of determining the reaction amount in the reaction of the molecular polymer and the crosslinking agent.

  That is, when a regenerated polymer is produced using the low molecular weight polymer obtained by the method of the present invention as it is or by mixing a cross-linking agent with the low molecular weight polymer and using them as a regenerative polymerization raw material, the reaction contained in the low molecular weight polymer. Since the re-reaction or the reaction between the low molecular weight polymer and the cross-linking agent occurs by the amount of the group, the smaller the amount, the shorter the reaction time required to obtain the regenerated polymer, and the cross-linking agent amount also increases. It will be less. Conversely, the greater the amount of reactive groups, the longer the reaction time required to obtain the regenerated polymer, and the greater the amount of cross-linking agent.

  The reactive group having such an action effect is obtained by bringing a high molecular polymer into contact with water under high-temperature and high-pressure conditions, whereby a —C (═O) O— or —C (═O) N— bond of the high molecular polymer is obtained. The amount of reactive groups can be controlled by appropriately changing the temperature and pressure conditions. That is, when the temperature and pressure are low and the contact time is short, the polymer does not decrease in molecular weight or decompose, so the amount of reactive groups in the resulting low molecular weight polymer is small and the molecular weight is large. On the other hand, when the temperature and pressure are increased and the contact time is lengthened, the lowering (decomposition) of the polymer proceeds effectively, and the amount of reactive groups in the resulting low molecular polymer increases and the molecular weight also decreases. .

  For example, when a high molecular polymer made of polyurethane is brought into contact with water under high temperature and high pressure, hydroxyl groups and amino groups are present in the resulting low molecular weight polymer molecule, and these reactive groups appear as hydroxyl value and amine value. A new polyurethane molded product can be obtained by mixing the low-molecular polymer by appropriately increasing or decreasing the amount of the cross-linking agent, that is, the diisocyanate according to the magnitude of the hydroxyl value and the amine value.

  Moreover, the low molecular polymer obtained by the method of the present invention can produce a coating, a powder coating, an adhesive, a fiber and a nonwoven fabric using the polymer. First, the paint using the low molecular weight polymer obtained by the method of the present invention will be described. As described above, the low molecular weight polymer obtained by the method of the present invention is in the form of liquid, paste, or granular depending on the type of polymer and conditions (temperature, pressure, contact time). When the low molecular polymer obtained by the method of the present invention is applied to a coating material, a low molecular polymer having a granular form is desirable.

  As the low molecular weight polymer applied to the coating material, those obtained from a crosslinked polymer or a high molecular weight polymer such as polyester, polyurethane, polyether, and epoxy are preferable, and these low molecular weight polymers are used as a coating film forming resin of the coating material. is there. The paint using the low molecular weight polymer obtained by the method of the present invention as a main binder resin includes, in addition to the solvent, various pigments including color pigments, rust preventive pigments, extender pigments, dispersants, antifoaming agents, and leveling agents. These various additives can be added. The coating material can be easily prepared by mixing the above components using a conventionally known mixer such as a propeller-type stirrer or a homogenizer.

  The low molecular weight polymer obtained by the method of the present invention is applied to a powder coating that can form a coating film on the surface of the substrate by applying it to the substrate without using a solvent and then curing it by baking. You can also When the low molecular weight polymer obtained by the method of the present invention is applied to a powder coating, the low molecular weight polymer used is a cross-linked polymer such as polyester, polyurethane, polyether, and epoxy, Powdery particles obtained from molecular polymers are preferred, and these low molecular weight polymers are used as coating film forming resins for paints.

When the low molecular weight polymer obtained by the method of the present invention is applied to a powder coating material, the powder coating material may contain, in addition to a powder resin composed of the low molecular weight polymer and a curing agent, a coloring pigment if necessary with a mixer. It can be obtained by dry blending. Moreover, after dry blending, it can also be produced by heat-melting and kneading using a kneader such as a twin screw extruder, cooling and pulverizing.

  The low molecular weight polymer obtained by the method of the present invention can also be used as an adhesive component. When the low molecular polymer obtained by the method of the present invention is used as an adhesive component of an adhesive, it is preferable to use a low molecular polymer obtained from a crosslinked polymer or a high molecular polymer such as polyester, polyurethane, polyether, and epoxy. In addition to the adhesive component composed of the low molecular weight polymer obtained by the method of the present invention, the adhesive may include a moisturizer, a dye, a surfactant, an antiseptic, an antifungal agent, and a pH adjuster as necessary. Additives such as an antifoaming agent and a rust preventive agent can be appropriately added as long as the effects of the adhesive component are not impaired. The adhesive can be easily prepared by mixing using a conventionally known mixer such as a propeller-type stirrer or a homogenizer.

  Moreover, the low molecular weight polymer obtained by the method of the present invention can also be used as a binder component that binds the constituent fibers of the nonwoven fabric. When the low molecular polymer obtained by the method of the present invention is used as a binder component, it is preferable to use a low molecular polymer obtained from a crosslinked polymer or a high molecular polymer such as polyester, polyurethane, polyether, and epoxy. The constituent fibers of the nonwoven fabric using the low molecular weight polymer obtained by the method of the present invention as a binder component are not particularly limited. For example, polyester fibers such as polyethylene terephthalate and polybutylene terephthalate, polyolefin fibers such as polypropylene and polyethylene, polyamide Fiber, acrylic fiber such as polyacrylonitrile, polyvinyl alcohol fiber, synthetic fiber such as synthetic pulp, semi-synthetic fiber such as rayon, natural fiber such as cotton and pulp fiber, glass fiber, ceramic fiber, metal fiber, etc. These inorganic fibers can be used alone or in combination.

  In addition, a filler, a flame retardant, a colorant, a light-proofing agent, an antibacterial agent, an antistatic agent, and the like can be added to the binder component composed of the low molecular weight polymer obtained by the method of the present invention.

  Moreover, the low molecular weight polymer obtained by the method of the present invention can also be used as a spinning material. When used as a spinning material, it is preferable to use a low molecular polymer obtained from a crosslinked polymer or a high molecular polymer such as polyester, polyurethane, polyether, polyamide, and polycarbonate. The fiber using the low molecular weight polymer obtained by the method of the present invention as a spinning material is not particularly limited, but the low molecular weight polymer obtained by the method of the present invention is the whole of the spinning material by melt spinning, dry spinning or wet spinning. Examples include fibers formed by melt spinning, dry spinning or wet spinning by mixing the formed fiber or the low molecular weight polymer obtained by the method of the present invention with other spinning materials as a part of the spinning material. Can do.

  Moreover, a filler, a flame retardant, a coloring agent, a light-resistant agent, an antibacterial agent, an antistatic agent, and the like can be added to the spinning material made of the low molecular weight polymer obtained by the method of the present invention.

  In addition, this invention is not limited to the following Example, It can implement freely by changing in the range described in the "Claims".

Recycling of polyethylene terephthalate (hereinafter referred to as PET) PET is a typical thermoplastic polyester resin that has a structure in which terephthalic acid and ethylene glycol are condensed to form a chain by an ester bond.

  PET was initially used as a material for fibers and films, but it was found that blow molding yields bottles with excellent transparency, gloss, and rigidity. It has come to be. In Japan, PET bottles were first adopted in the soy sauce industry in 1977, and five years later, in 1982, they were approved for use as soft drink containers by the Ministry of Health and Welfare. The consumption of PET is about 530,000 tons, which is about four times that in 1993 compared to about 120,000 tons in 1993.

  There are two types of PET bottle recycling, separate collection and over-the-counter collection by local governments. However, there are overwhelmingly more local government collections, which raises the problem of increased collection costs for local governments. The collected PET bottles are made into flakes, pellets, etc., which are the starting materials for recycled products after the separation, washing, and pulverization processes.

Conventional PET chemical recycling includes a methanolysis method that decomposes in liquid methanol, a glycolysis method that decomposes in liquid ethylene glycol, and a hydrolysis method in liquid water, all of which have a reaction time of 5 hours or more. However, there is a problem that a catalyst is necessary. Furthermore, supercritical research is being conducted to decompose PET in a short time without using a catalyst. For example, in a reaction using supercritical methanol at 300 ° C. and 15 MPa, PET is decomposed in 10 minutes. However, since the monomer is recovered as dimethyl terephthalate, a hydrolysis process to terephthalic acid is required. Furthermore, when PET is hydrolyzed in supercritical water at 400 ° C. and 40 MPa, it completely decomposes in 5 minutes, and the monomer terephthalic acid is recovered in a high yield. On the other hand, the yield of ethylene glycol, another monomer, was greatly reduced because terephthalic acid was used as an acid catalyst to promote the decomposition of ethylene glycol. Research reports that in subcritical water at 300 ° C, which is milder than supercritical water, PET was almost completely decomposed in 10 minutes, and terephthalic acid and ethylene glycol were recovered in 89% and 93% yields. is there. However, when the equipment capable of withstanding high pressure and high temperature exceeds 3 MPa, it is necessary to specially manufacture a boiler, a pressure resistant container, a valve, and piping. In particular, the larger the device, the more the cost increases and the practicality becomes lower.

  The method of the present invention proposes a PET recycling method using a treatment of contacting with water under high temperature and high pressure. According to the method, a catalyst such as an acid or an alkali or a solvent such as ethylene glycol or methanol is also used. It is thought that PET can be hydrolyzed without use, and the labor and cost required for processing can be greatly reduced.

  A batch blasting tester manufactured by Nisaka Manufacturing Co., Ltd. was used for the treatment to be brought into contact with water under high temperature and high pressure. The apparatus has a pressure resistance of 3.0 MPa, the boiler is a TMO-300 type manufactured by Takuma Corporation, has a maximum working pressure of 3.0 MPa, and an equivalent evaporation amount of 300 kg / h.

  A sample obtained by cutting a commercially available PET bottle into 3 cm × 10 cm was placed in a blasting apparatus, and at 200 ° C. (1.6 Mpa), 30 minutes, 60 minutes, 120 minutes, 180 minutes, 240 minutes, 225 ° C. (2 .6 MPa) for 30 minutes, 60 minutes, and 120 minutes, respectively, and contact with water under high temperature and high pressure.

Conditions for high-pressure steam treatment of PET

Analyzing experiment of PET degradation product Surface observation by scanning electron microscope (SEM) In order to observe the surface of the degradation product by contact with water under high temperature and high pressure, the sample was dried under reduced pressure, then osmium-deposited and SEM (S-3000N). , Manufactured by Hitachi) and observed at 500 times.

Measurement of particle size distribution by laser diffraction Add about 200 ml of isopropyl alcohol as a dispersion medium to a flow cell of LA-910 (manufactured by Horiba Ltd.), and add a sample so that the amount of transmitted light is 95 to 70%, and perform ultrasonic dispersion for 4 minutes. The particle size distribution was measured.

Measurement of TG A 10 mg sample was placed in a platinum pan (oven), and measured with EXSTAR-6000 TG / DTA6300 manufactured by SII Technology from 50 ° C to 1000 ° C at a heating rate of 10 ° C / min.

Measurement of glass transition point, crystallinity, and melting point by DSC A 10 mg sample was placed in an aluminum pan (oven) and heated at 300 ° C. for 15 minutes in an electric furnace manufactured by HIRANUMA, and rapidly cooled. After that, measurement was performed from 25 ° C. to 300 ° C. at a temperature rising rate of 5 ° C./min with EXSTAR-6000 DSC6200 manufactured by SII Technology.

Measurement of crystallinity by XRD In order to examine the crystallinity of PET powder that had been subjected to high-pressure steam treatment, a sample was measured by XRD (manufactured by RINT-Ultima llll / PCrigaku). The target was Cu, the X-ray source was 40 kV / 40 mA, and 2θ was measured in the range of 10 to 40 °.

At structural analysis JEOL ECA500 by ¹³ C-NMR, was spectrum measured by CP / MAS ¹³ C-NMR.

Molecular weight measurement based on intrinsic viscosity A 200 mg sample was taken, 50 ml of a mixed solvent (phenol: tecachloroethane = 60: 40) was added, and the sample was dissolved at 90 ° C. 10 ml of the dissolved solution was measured with an Ostwald viscometer and kept at 25 ° C., then the outflow time of the test solution was measured, and the molecular weight was obtained from the Mark-Houwink-sakurada equation ^[11] .
[n] = K ・ Mα
K × 10 ⁴ = 7.44
α = 0.648

Molecular weight measurement by GPC 2 mg of a sample was dissolved in 0.4 ml of chloroform / hexafluoroisopropanol (HFIP) = 3/2 (v / v) and then diluted with 7.6 ml of chloroform to prepare a sample solution (0.025 %). It filtered with the 0.2 nm membrane filter, and GPC analysis of the obtained sample solution was implemented on condition of the following.
Device: Shodex GPC SYSTEM-21
Column: TSKgelGMH _XL x 2 + TSKgel G2000H _XL (TOSOH)
Solution: Chloroform / HFIP = 98/2 (v / v)
Flow rate: 0.7 ml / min
Temperature: 40 ° C
Detector: UV (254 nm)
The molecular weight was calculated in terms of standard polystyrene.

Quantification of end groups by ¹ H-NMR Measurement was carried out using a solvent shown below for the hydroxyl terminal and carboxylic acid terminal in AVANCE 500 manufactured by BRUKER. The sample treated at 200 ° C. for 120 minutes or more and 225 ° C. for 30 minutes or more did not completely dissolve in both conditions, and thus became cloudy. Therefore, the sample was centrifuged and the supernatant was measured (liquid 2 in FIG. 1).

(1) a hydroxyl-terminated quantitative sample 7mg weighed, dissolved in CDCl ₃ /HFIP=1/1(v/v)0.3ml, further CDCl ₃ added 0.3ml and heavy pyridine 30 nl, ¹ H-NMR It was measured.
(2) Determination of acid terminal 7 mg of a sample was weighed and dissolved in 0.3 ml of CDCl _{3 /} HFIP = 1/1 (v / v), and further 0.3 ml of CDCl ₃ and 60 nl of 0.2 M triethylamine in deuterated chloroform were added. And ¹ H-NMR measurement was performed.

Calculation of Yield (1) Yield of terephthalic acid 240 minutes of PET degradation product insoluble in ¹ H-NMR solvent was centrifuged, the precipitate was filtered and dried, Measured (solid 2 in FIG. 1).
(2) After the ethylene glycol yield was treated for 240 minutes, the apparatus was cooled to room temperature and the liquid was recovered (liquid 1 in FIG. 1). Ethylenediamine (20 mg / ml) was added here as a standard substance and analyzed by ¹ H-NMR.

Results and Discussion As shown in FIG. 2, when the contact with water was performed under high temperature and high pressure, PET became brittle, cracked, and changed to a fine powder. In particular, PET treated for 120 minutes or more changed to a white fine powder. The sample treated for 240 minutes was also able to observe the gloss seen in the crystals of terephthalic acid.

  In order to confirm the change in the particle size of the powder obtained by the contact with water under high temperature and high pressure, the particle size distribution was measured by laser diffraction, and the median diameter for each processing time is shown in FIG. It can be confirmed that the particle size decreases as the treatment time increases.

Moreover, the sample which performed the process made to contact with water under PET and high temperature / high pressure performed surface observation with the scanning electron microscope (SEM). From FIG. 4 and FIG. 5, it can be determined that decomposition has occurred from the surface by the treatment. This is thought to be because hydrolysis of the ester bond is promoted by water attacking the PET surface by treatment with water under high temperature and high pressure. In the treatment of contacting with water under high temperature and high pressure, the ion product increases as the temperature increases (log Kw≈-11), and the ion product is about 1000 times as high as that of normal water. It is thought that an emphasis reaction occurs in which a cationoid reaction by [ ⁺ ] and an anionoid reaction by [OH ⁻ ] occur simultaneously.

It was also confirmed that the sample treated for 240 minutes was decomposed to a size equivalent to that of terephthalic acid, which is a PET raw material. Furthermore, thermal analysis was performed to confirm the characteristics of the decomposition product. The measurement results of TG are shown in FIG. As shown in FIG. 6, the first weight change point of the TG curve was T ₁ and the second weight change point was T ₂ . From the TG curve, it can be seen that the PET decomposition temperature is 409.4 ° C., terephthalic acid is 305.0 ° C., and the samples treated for 120 minutes and 180 minutes have both decomposition points of PET and terephthalic acid.
Temperature of weight change point by TG

FIG. 7 and Table 3 show the measurement results of the glass transition point (T _g ), crystallization temperature (T _c ), melting start temperature (T _im ), and melting point (T _m ) by DSC. Up to 120 minutes of high-pressure steam treatment time, glass transition point (72.1 ° C → 65.9 ° C), crystallization temperature (125.6 ° C → 97.0 ° C)
), Melting start temperature (223.4 ° C. → 181.6 ° C.), and melting point (247.6 ° C. → 237.1 ° C.) are shifted to the low temperature side. This is thought to be due to the progress of decomposition and lower molecular weight. In addition, the endothermic peak of melting broadens as processing time increases. This suggests that hydrolyzed products with different molecular weights appear and the molecular weight distribution is widened. Samples treated for 180 minutes show different DSC curves because the molecular structure is different due to further progress in molecular weight reduction and removal of ethylene glycol as a monomer from the solid part. to decide. Moreover, the sample which performed the high pressure steam process for 240 minutes has shown the DSC curve similar to a terephthalic acid.
Change in thermal characteristics during processing time by DSC

Measurement of Crystallinity As shown in FIG. 8, PET has a repeating unit in which a benzene ring and an ethylene chain are connected by an ester bond, and the crystal structure is a triclinic system belonging to the space army P1-Ci1. In the crystal, the carbonyl group and the benzene ring form a substantially flat surface.

Therefore, in order to observe the change in crystallinity due to the treatment with water under high temperature and high pressure, XRD was measured, and the result is shown in FIG. When the treatment is performed for 30 minutes and 60 minutes, peaks at 2θ = 18 °, 23 °, and 26 ° increase. These are peaks of the (1 0 0), (010), and (1 1 0) planes of PET, and it was found that the degree of crystallinity of PET increases with treatment. In addition, in the case where the treatment was performed for 180 minutes, the peaks at 2θ = 17.4 ° and 27.9 ° increased. These peaks are peaks on the (110) plane and the (200) plane of terephthalic acid, suggesting that decomposition has occurred up to the monomer terephthalic acid.

  The sample treated for 240 minutes has the same pattern as the monomer terephthalic acid, and X-ray diffraction shows that PET is decomposed to the monomer.

The measurement result of ¹³ C-NMR is shown in FIG. In the sample that had been treated with water under high temperature and high pressure for 120 minutes or more, the carbonyl carbon signal (172 ppm) of the carboxylic acid was confirmed, the decrease of the methylene carbon signal (61 ppm) adjacent to the ester, and the hydroxyl group It can be seen that the ester bond was decomposed by the appearance of a signal (67 ppm) of methoxy carbon possessed by. Furthermore, the sample which processed for 240 minutes was not able to confirm the signal of ethylene carbon. This indicates that ethylene glycol obtained by decomposition of PET into monomers by treatment was removed from the solid and that it was terephthalic acid as in the DSC and X-ray diffraction results. In addition, the carbonyl carbon signal (172 ppm) of the carboxylic acid has a lower intensity than the aromatic, because it is a quaternary carbon, so that the relaxation time becomes longer.
This is also because the influence of the Overhauser effect is small.

Furthermore, as the ester bond is broken, C2 (134 ppm) shifts to a higher magnetic field, C3 (130 ppm) shifts to a lower magnetic field, and finally the peaks overlap.
0 min: δ 164 (COO), 133 (aromatic C adjacent to
the ester), 133 (aromatic C), 62 (COOCH ₂ ),
30 minutes: δ 163 (COO), 133 (aromatic Cadgent to the ester), 133 (aromatic C), 62 (COOCH ₂ ),
60 minutes: δ 163 (COO), 133 (aromatic Cadient to the ester), 133 (aromatic C), 62 (COOCH ₂ ),
120 minutes: δ 172 (COOH), 163 (COO), 134 (aromatic C), 67 (HOCH ₂ ), 61 (COOCH ₂ ),
180 minutes: δ 172 (COOH), 131 (aromatic C), 67 (HOCH ₂ ), 61 (COOCH ₂ ),
240 min: δ 173 (COOH), 131 (aromatic C).

  Table 4 shows the results of molecular weight measurement based on intrinsic viscosity. It can be seen that the weight average molecular weight is reduced from 41000 to 500 by the treatment with water at high temperature and high pressure. In addition, the sample which processed 120 minutes or more was not measured since it was insoluble in the solvent used for the intrinsic viscosity measurement of PET, and became cloudy. Also from this fact, it can be inferred that by increasing the treatment time, the molecular weight is lowered to the point where the solubility is different.

Furthermore, the molecular weight and molecular weight distribution were analyzed by GPC, and the results are shown in Table 4 and FIG. The sample treated for 30 minutes has a PDI as large as 10.9, indicating the broadening of the molecular weight distribution. Also in the GPC analysis, the sample treated for 60 minutes or more did not completely dissolve in the solvent, and because the treated sample had a low molecular weight, there was no standard substance and measurement was not possible. Therefore, the number average molecular weight was determined from the integrated value of ¹ H-NMR.
A treatment (200 ° C.) for contacting with water under high temperature and pressure was performed.
PET molecular weight measurement results

The measurement results of ¹ H-NMR are shown in FIGS. The number average molecular weight was calculated according to the following formula. In addition, isophthalic acid and diethylene glycol are also present, but they were not included in the calculation due to their trace amounts.

The calculation results of the number average molecular weight are shown in Table 4, and the difference in number average molecular weight between 200 ° C. and 225 ° C. is shown in FIG. Moreover, the sample which processed for 120 minutes or more at 200 degreeC and 30 minutes or more at 225 degreeC did not melt | dissolve in a < ¹ > H-NMR solvent completely. Therefore, each sample was centrifuged to separate the dissolved portion (liquid 2) and the insoluble portion (solid 2), and only the dissolved portion was measured. ^The number average molecular weight calculated from ¹ H-NMR was calculated lower than the result of GPC, but the tendency to lower the molecular weight is the same. Moreover, PET that has been treated for 180 minutes or more at 200 ° C. has decreased to a level comparable to that of terephthalic acid (M: 166.1).

The precipitate (solid 2) obtained by centrifugation was found to be terephthalic acid as shown by the ¹ H-NMR spectrum (FIG. 20). The proportion of terephthalic acid increased with increasing treatment conditions, accounting for 90% for the sample treated at 200 ° C. for 240 minutes and 225 ° C. for 120 minutes. (Fig. 23)

From these results, the treatment at 225 ° C. shows that the reaction rate is twice that of the treatment at 200 ° C. Furthermore, the hydroxyl group and the acid group were quantified from the integrated value of ¹ H-NMR. The calculation results are shown in FIGS. It can be seen that the amount of hydroxyl group and carboxyl group is increased by increasing the treatment time. However, when treated at 200 ° C. for 120 minutes and at 225 ° C. for 30 minutes or more, the amount of hydroxyl groups decreases. This is judged to be due to the separation of ethylene glycol decomposed to the monomer from the solid content. Also from this result, it was recognized that PET was decomposed into oligomers and further into monomers by the treatment with water under high temperature and high pressure.

After the treatment of contacting with water under high temperature and high pressure, the apparatus was returned to room temperature, the liquid part was recovered (liquid 2), and analyzed by ¹ H-NMR in heavy water. From FIG. 26, it was confirmed that the liquid 2 contains ethylene glycol. Furthermore, the concentration of ethylene glycol was calculated from the integral value with ethylenediamine added as a standard substance.

In order to determine the yield, the ethylene glycol and terephthalic acid content of PET was calculated from the integrated value of ¹ H-NMR in FIG. 11 to be 67% and 31%, and the remaining 2% was diethylene glycol and isophthalic acid. Met. When treated for 240 minutes, the yields of terephthalic acid and ethylene glycol are 64% and 29%, respectively, and the values are 96% and 94%, respectively, when PET is completely decomposed. Monomer was recovered.

Examination of recycling Examination for practical application A treatment (200 ° C.) in which a commercially available PET bottle (500 ml) was brought into contact with water in the same shape under high temperature and high pressure was performed. As shown in FIG. 27, even if the PET bottle was processed as it was, it could be recovered as a powder without applying physical force.

  The thickness of the PET bottle is from 0.25 mm to 1.5 mm even at the opening portion, and even if mass production is performed, if water can contact the surface under high temperature and high pressure, as in the experimental level, acids and alkalis can be used. It can be recovered in powder form without using a catalyst or solvent, and it is considered that the processing time does not increase. In addition, currently collected PET bottles are formed into pellets and flakes through processes such as separation, pulverization, and washing. However, in the process of contacting with water under high temperature and high pressure, these stages are made one stage. Can be done.

Examination of utilization method of PET degradation products As a utilization method of PET degradation products, application in powder coating is currently being studied. If PET for powder coating is cured, mechanical properties are not required, and if the molecular weight can be controlled, it can be considered as a recycling application. In the PET degradation product, carboxylic acid appears at the terminal by hydrolysis, as revealed by quantitative determination of terminal groups. Currently, terminal carboxyl group type saturated polyester resins are used, and epoxy resins are used as curing agents. Therefore, 58 g of the PET degradation product treated for 30 minutes, 42 g of Epicoat 1003F (oiled shell epoxy) bis-A epoxy as a curing agent and 0.2 g of imidazole as a curing catalyst were mixed and heated at 170 ° C. for 20 minutes. Repolymerization was attempted. During polymerization, PET can only be used as a powder coating in a baking state heated at 250 ° C. for 30 minutes, whereas the melting point starting temperature has dropped from 223.4 ° C. to 221.3 ° C., and the endothermic peak has become broad. The degradation product of PET was able to react with epoxy at 170 ° C.

  The obtained polymer was subjected to viscoelasticity measurement by Rheology DVE-V4. The result is shown in FIG. From FIG. 28, the tan δ of the sample using the decomposition product of PET is improved in any temperature range as compared with PET. This is considered to be due to the fact that PET has been decomposed and the molecular weight is not constant, so the melting point is widened, so that the vibration damping property is also improved.

  It was found that PET can be recovered in the form of low molecular weight and crystallized powder by the contact with water under high temperature and high pressure according to the present invention. Furthermore, it was found that the monomer was decomposed by increasing the treatment time. It was also found that the reaction rate was doubled by raising the temperature condition from 200 ° C to 225 ° C.

In addition, since this treatment does not require a catalyst such as an acid or an alkali, no purification after the treatment is necessary, and the environment is not adversely affected. The yields of terephthalic acid and ethylene glycol after high-pressure steam treatment at 200 ° C. for 240 minutes are 64% and 29%, and the values are 96% and 94% when PET is completely decomposed, respectively. The monomer can be recovered in a high yield. Therefore, it is considered possible to recycle from the bottle with the highest added value to the bottle as the recycling law. In 2006, the production of terephthalic acid in Japan was 1.43 million tons and the production of ethylene glycol was 760,000 tons, which can be reused as raw materials.

  As can be seen from the analysis results, the decomposition product decreases to terephthalic acid, which is a raw material, and it is possible to recover ethylene glycol having a boiling point of 197.6 ° C. by distillation in a sealed apparatus. Predictable.

  Current recycling of PET bottles requires the steps of removing foreign substances, cleaning, and crushing after collection, but with high-pressure steam treatment, these can be performed in a single step, greatly reducing recycling costs. Think of things. And if the cost of remanufactured products decreases, the reuse application will become wider.

  In the production method of the present invention, a high-molecular-weight polymer synthesized by condensation polymerization and having a —C (═O) O— or —C (═O) N— bond in the linear chain of the molecule is used. By bringing the polymer polymer into contact with water under the condition, the —C (═O) O— or —C (═O) N— bond of the polymer is cleaved so that the molecular weight of the polymer is 90% or less before the bond cleaving. Thus, the low molecular weight polymer is manufactured, but the low molecular weight polymer can also be manufactured from the monomer for the purpose of reducing the cost related to the polymer manufacturing.

Claims (13)

  A polymer synthesized by condensation polymerization and having a bond of —C (═O) O— or —C (═O) N— in the linear chain of the molecule is brought into contact with water under high temperature and high pressure, whereby the polymer A method for producing a low molecular weight polymer, characterized by cleaving a -C (= O) O- or -C (= O) N- bond in a polymer so that the molecular weight of the polymer is 90% or less before the bond breakage.   The method for producing a low molecular weight polymer according to claim 1, wherein the high molecular polymer having a bond of -C (= O) O- or -C (= O) N- on the straight chain of the molecule is an ester. .   3. The polymer according to claim 2, wherein the high molecular polymer having a bond of —C (═O) O— or —C (═O) N— on a linear chain of the molecule is a polyester polymer or an acrylic polymer. A method for producing a low molecular weight polymer.   The method for producing a low-molecular polymer according to any one of claims 1 to 3, wherein the high-molecular polymer before bond breaking is a polymer molded product.   The polymer polymer before bond breaking is brought into contact with water at 100 ° C. or more and 0.1 MPa or more, so that —C (═O) O— or —C (═O) N— The method for producing a low molecular weight polymer according to any one of claims 1 to 4, wherein the bond is broken.   By contacting the polymer before bond breaking with water under the conditions of 400 ° C. and 0.2 to 3.0 MPa, —C (═O) O— or —C (═O) N of the polymer The method for producing a low molecular weight polymer according to claim 5, wherein the bond of − is cleaved.   It is characterized by cleaving the —C (═O) O— or —C (═O) N— bond of the polymer polymer by bringing the polymer polymer before bond cleavage into contact with water for 1 to 300 minutes. The method for producing a low molecular weight polymer according to any one of claims 1 to 6.   The low molecular polymer obtained by the manufacturing method of the low molecular polymer in any one of Claims 1-7.   The low molecular polymer according to claim 8, wherein the polymer is in the form of a powder.   A paint comprising the low molecular weight polymer according to claim 8.   A powder coating material using the low molecular weight polymer according to claim 8.   An adhesive comprising the low molecular weight polymer according to claim 8.   A nonwoven fabric characterized by using the low molecular weight polymer according to claim 8 as a binder for bonding constituent fibers to each other.