JP2001151879A - Recycle of recovered polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient recycling process for recovered polyester. SOLUTION: When recovered polyester and the diol component of the polyester are melt-mixed to effect depolymerization of the polyester and the depolymerization product is polycondensed again, at least one of pore-forming agent selected from an aliphatic component including ionically dissociating group, ionically dissociating group-including aromatic components, acetic acid, metal acetate salts, acetic esters, phosphoric acid, metal phosphate salts and phosphoric esters is added to the condensed polymer whereby porous polymer is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for regenerating recovered polyester, and more particularly, to an effective method for regenerating recovered polyester such as recovered PET bottles and fibers.

[0002]

2. Description of the Related Art In recent years, recycling of resources has been demanded, and polyethylene terephthalate (hereinafter sometimes abbreviated as PET), PET for clothing and clothing, and polyethylene naphthalate (hereinafter sometimes abbreviated as PEN). Resin molded products also need to be collected and reused. However, most of the recovered PET contains impurities, and even if the PET is re-melted and molded as it is, only poor quality PET can be obtained.

[0003] Therefore, the collected material is separated and decomposed,
In most cases, the raw material is purified and recovered as a dicarboxylic acid component (JP-A-9-208524, JP-A-10-87529, JP-A-10-287774).
Japanese Patent Application Laid-Open Publication No. 2000-157, and it is troublesome, and there is a problem that the price becomes considerably high.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for solving the problems of the above-mentioned prior art and for efficiently recovering the recovered polyester.

[0005]

Means for Solving the Problems In view of the above prior art, the present inventors have made intensive studies on a method for regenerating polyester, and as a result, have completed the present invention.

That is, an object of the present invention is to prepare a recovered polyester and a diol component having a molecular weight of 50 to 200, which is 0.3 to 100 times the weight of the polyester, by 150 to 150 times.
Melt and mix at 300 ° C. to perform a depolymerization reaction, and if necessary, perform a polycondensation reaction at any time when performing a polycondensation reaction after purifying by removing impurities by performing a separation operation while maintaining a molten state. Examples of the porosity-imparting component include an aliphatic component containing an ion-dissociable group, an aromatic component containing an ion-dissociable group, acetic acid, a metal salt of acetic acid, an acetic acid ester compound, phosphoric acid, a metal salt of phosphoric acid, and a phosphoric acid ester compound. At least one chosen
This is achieved by a method for regenerating the recovered polyester, in which seed components are added to obtain a porous polymer.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The recovered polyester of the present invention is a product obtained by recovering polyester products such as bottles, fabrics, resin molded products, and the like, and non-qualified products generated in a manufacturing stage. Terephthalate,
Polyethylene naphthalate, copolymerized polyethylene terephthalate in which 70% by weight or more, preferably 80% by weight is ethylene terephthalate based on all repeating units, 70% by weight or more based on all repeating units, preferably 80% by weight of 2,6-ethylene naphthalene A copolymerized polyethylene naphthalate that is a carboxylate,
Alternatively, it comprises a polyester mixture in which other polyesters are mixed with less than 30% by weight, preferably less than 20% by weight.

The copolymerizable components include, for example, aromatic phthalic acid, isophthalic acid, naphthalenedicarboxylic acids, aliphatic dicarboxylic acids having 4 to 12 carbon atoms, aliphatic diols having 3 to 10 carbon atoms, and cyclohexane. Examples include alicyclic diols such as dimethanol, aromatic diols such as bisphenol A, and hydroxycarboxylic acids such as oxycaproic acid and oxybenzoic acid.

[0009] Polyether glycols such as polyethylene glycol and polytetramethylene glycol can also be copolymerized.

Examples of the polyester that may be mixed include polybutylene terephthalate, polybutylene naphthalene dicarboxylate, polycyclohexane dimethylene terephthalate, and polyether / ester block copolymers and polyester / ester block copolymers known as polyester elastomers. Polymers.

In the regeneration method of the present invention, the above-mentioned recovered polyester and a diol component having a molecular weight of 50 to 200 must be melt-mixed at 150 to 300 ° C. and subjected to a heating / depolymerization reaction. The depolymerization reaction is carried out by adding a diol component in an amount of 0.3 to 100 times, preferably 2 to 50 times, based on the weight of the polyester, and if necessary, adding a transesterification catalyst. The temperature of the melt mixing is preferably 180
２５０250 ° C.

At this time, even if a substance other than polyester is mixed, there is no problem as long as the compound does not adversely affect the depolymerization reaction. Specifically, the mixing ratio is 20 wt.
If it is about%, there is often no problem. The depolymerization reaction has different reaction conditions depending on the temperature, the amount of the diol component, the effectiveness of the transesterification catalyst, and the like.
It can be controlled by adding a catalyst. When a transesterification catalyst is added, it is preferable to add a catalyst deactivator such as a phosphoric acid compound after the completion of the reaction.

The depolymerization reaction product thus obtained is preferably used after subjecting it to a treatment such as separation of solid matter or phase separated matter. This separation step is effective because the recovered polyester often contains impurities. This separation operation is not particularly limited as long as the temperature at which the depolymerization reaction product maintains a molten state, but a higher temperature is preferable because the melt viscosity becomes lower and the separation operation becomes easier. Any known means such as general filtration, centrifugation, and liquid-liquid separation can be used for this separation.

Next, when performing the polycondensation reaction, it is preferable to add a polycondensation reaction catalyst as necessary.
As the catalyst, any catalyst generally used for polymerization of polyesters such as titanium compounds such as titanium tetraalkoxide, tin compounds such as dialkyltin oxide and dialkyltin acetate, and antimony compounds such as antimony oxide is used. be able to. The amount of the catalyst to be added may be about the same as in a normal polymerization reaction, and generally,
It is 1 to 200 mmol% based on the dicarboxylic acid component.

The polycondensation reaction is carried out at 150 to 300 ° C., preferably 180 to 280 ° C., at atmospheric pressure under an inert atmosphere, after removing diols mainly composed of ethylene glycol, and gradually reducing the pressure. Promotes a polycondensation reaction under a vacuum of 100 mmHg or less to obtain a porous polyester.

For the production of the porous polyester, a stirring tank or a reduced-pressure stirring device capable of continuously feeding the polymer is used.

The present invention is characterized in that a porosity-imparting component is added during this series of reaction steps. In particular, it is preferable to add the porosity-imparting component at the start of melt-mixing, since the porosity-imparting component serves as a depolymerization catalyst and shortens the depolymerization reaction.

The term "porosity-imparting component" as used herein means that the polyester is made into a fiber, and when the polyester is treated with hot water, an alkaline aqueous solution, or the like, a property that micropores are easily formed on the surface of the fiber. Means a component that can

Specific examples of the porosity-imparting component include an aliphatic component containing an ion-dissociable group, an aromatic component containing an ion-dissociable group, acetic acid, a metal salt of acetic acid, an acetic acid ester compound, phosphoric acid, and a metal salt of phosphoric acid. And at least one component selected from the group consisting of phosphoric acid ester compounds.

The amount of the porosity-imparting component may be appropriately selected depending on the effect of the present invention and the degree of pore-forming property of the produced porous polyester. The amount added is preferably from 0.2 to 2 based on the weight of the polyester.
00 wt%.

Further, the polyester of the present invention comprises a diol component having a molecular weight of 3,000 to 20,000, a nonionic dissociable aromatic-containing dicarboxylic acid component or an ester compound thereof, a nonionic dissociable aliphatic dicarboxylic acid component or an ester compound thereof, and the like. May be added as necessary.

The porous polyester thus obtained may contain, in addition to the porosity-imparting component, another polymer, a stabilizer,
Pigments, dyes, twisting agents, nucleating agents, lubricants and other additives may be added and used. The amount of these additives and polymers is 0.01 to 10 based on the weight of the porous polyester.
wt%.

In producing the fiber or composite fiber using the easily hydrolyzable polyester of the present invention, any known method for producing a fiber or composite fiber can be employed, but the polymer as the fiber-forming component can be used. The composite state of the polyester with the porous polyester of the present invention may be a core-sheath type, an eccentric core-sheath type, a side-by-side type, a sea-island type composite spun fiber or a sea-island type mixed spun fiber, a tangerine tuft type Any known composite state such as coordination (split) fiber may be used, but it is necessary that the porous polyester be a fiber or a composite fiber arranged so as to be exposed at least on the fiber surface. Further, it may have one or more hollow portions. The outer shape of the fiber cross section and the shape of the core do not need to be a perfect circle, and may be a polygon, a fin, a dumpling or the like.

Further, in forming micropores on the fiber surface after the obtained fiber or composite fiber is formed into a fabric, any of the known conditions of reducing hot water and reducing alkali can be adopted. Just choose.

[0025]

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

Example 1 240% by weight of ethylene glycol was added to a recovered polyester composed of 100% by weight of polyethylene terephthalate, and the following structural formula was used as a porosity-imparting component:

[0027]

Embedded image After adding 5 wt% of a compound represented by C ₁₂ H ₂₅ —C ₆ H ₄ —SO ₃ Na, adding 0.1 wt% of tetrabutoxytitanium as a catalyst, heating and stirring at 205 ° C. for 4 hours, The solid matter is filtered through a 40-mesh wire gauze, and 0.1 wt% of tetrabutoxytitanium is further added as a catalyst to the filtrate, and then transferred to a high-vacuum stirring tank. The polycondensation reaction was carried out for 80 minutes under reduced pressure to obtain a porous polyester.

Next, the porous polyester obtained by the above operation was spun according to a conventional method to obtain a fiber. The obtained fiber is made into a plain woven fabric, and an alkali weight reduction treatment is performed in an aqueous sodium hydroxide solution (concentration: 1 wt%) at a temperature of 100 ° C.
Minutes, the fiber surface was observed with an electron microscope.
Fine holes were observed.

Example 2 Ethylene glycol (240% by weight) was added to a recovered polyester composed of 100% by weight of polyethylene terephthalate, and the following structural formula was used as a porosity-imparting component:

[0030]

After adding 0.5 wt% of a compound represented by C ₁₄ H ₂₉ —SO ₃ Na and adding 0.1 wt% of tetrabutoxytitanium as a catalyst,
After heating and stirring for an hour, the solid matter was filtered through a 40-mesh wire gauze, and 0.1 wt% of tetrabutoxytitanium was further added as a catalyst to the filtrate, and then transferred to a stirring tank capable of high vacuum, and gradually heated at 280 ° C. The polycondensation reaction was performed for 70 minutes under a reduced pressure of 20 mmHg or less to obtain a porous polyester.

Next, the porous polyester obtained by the above operation was spun according to a conventional method to obtain fibers. The obtained fiber is made into a plain woven fabric, and subjected to alkali reduction treatment in an aqueous solution of sodium hydroxide (concentration: 1 wt%) at a temperature of 100 ° C.
Minutes, the fiber surface was observed with an electron microscope.
Fine holes were observed.

[0032]

According to the present invention, the porous polyester can be easily and efficiently obtained from the recovered polyester, and the recovered polyester can be effectively used. In addition, the fibers or composite fibers containing the porous polyester obtained as an extraction component according to the present invention can easily generate pores by hot water treatment or alkali treatment. Can be.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J029 AB07 AC02 AE06 BD04A BF25 CA02 CB04A CB05A CC05A EB05A JA253 JA263 JB133 JB163 JB173 JC583 JE182 JF251 JF371 JF471 KB16 KE05 KG01 KG01 KG02

Claims (8)

[Claims] 1. The recovered polyester and a molecular weight of 50 to 20 times 0.3 to 100 times the weight of the polyester.
When the depolymerization reaction product obtained by melt-mixing with a diol component of No. 0 at 150 to 300 ° C. is subjected to a polycondensation reaction, at an optional stage until the completion of the polycondensation reaction, ionic At least one member selected from the group consisting of a dissociable group-containing aliphatic component, an ion-dissociable group-containing aromatic component, acetic acid, a metal salt of acetic acid, an acetic acid ester compound, phosphoric acid, a phosphoric acid metal salt, and a phosphoric acid ester compound; A method for regenerating a recovered polyester by adding a component to obtain a porous polymer. 2. The polycondensation reaction according to claim 1, wherein a decondensation product obtained by melt mixing is subjected to a separation operation while maintaining a molten state to remove impurities and to purify, followed by a polycondensation reaction. Playback method. 3. The method according to claim 1, wherein the time at which the porosity-imparting component is added is the time at which the melt-mixing is started. 4. The method according to claim 1, wherein the diol component having a molecular weight of 50 to 200 is ethylene glycol. 5. The method according to claim 1, wherein the recovered polyester is recovered polyethylene terephthalate. 6. The method according to claim 1, wherein the recovered polyester is recovered polyethylene naphthalate. 7. The method according to claim 1, wherein the recovered polyester is recovered polybutylene terephthalate. 8. The method according to claim 1, wherein the recovered polyester is recovered polytrimethylene terephthalate.