JPH0873646A - Method for refining thermoplastic polyester resin - Google Patents

Abstract

(57) [Abstract] [Purpose] To develop an industrial method for regenerating a polyester resin of a sufficiently reusable quality even when a small amount of a different resin is mixed in the thermoplastic polyester resin. [Structure] (Example 1) PET resin (HDPE 2.5 wt
% Of 200%) was heated under reflux with 2 L of chlorobenzene for 1 h, and a PET resin was obtained by heating filtration and dried. [Effect] The amount of PET resin recovered is almost all. Elution time 1 h.
Almost all of the elution solvent recovered. 5g of filtrate residue is mixed HDP
E.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing a foreign resin from a "different resin containing thermoplastic polyester resin" in which another resin is mixed with a thermoplastic polyester resin. Specifically, in response to the recovery and reuse that has started to be emphasized in environmental issues, polyethylene terephthalate (PET) bottles, which occupy the majority of resin containers, are recovered, and polyolefin resins such as polyethylene and polypropylene mixed in the waste and polychlorination are collected. It relates to a method for removing chlorine-containing resins such as vinyl (PVC) and polyvinylidene chloride (PVDC) and reusing them as a purified thermoplastic polyester resin.

[0002]

2. Description of the Related Art PET bottle waste used as a soft drink container is recovered, and even if the waste is crushed for the purpose of recycling and recycling a thermoplastic polyester resin, the PET bottle label, polyolefin Since the crushed pieces of the bottle made of chlorine, the crushed pieces of the bottle made of chlorine-containing resin, and the like are mixed, the regeneration of the thermoplastic polyester resin is hindered. Therefore, it is necessary to efficiently remove the mixed different resin.

However, in the conventional removal (separation) technique, the different resin is separated by a mechanical means regardless of whether it is manual or mechanical, so that it is almost impossible to remove the different resin efficiently and completely. It was possible.

Further, when the PET resin and the different resin are compounded, for example, when they are a mixture (composition) or when they are laminated, separation / removal by mechanical means is often performed. It is difficult to do.

[0005]

An object of the present invention is to improve the quality of recycled PET resin and create a state suitable for reuse by removing the different resin from a mixed system of the different resins and purifying the PET resin. Especially. At the same time, an object of the present invention is to provide a purification system in which an organic solvent used for purification can be almost completely recovered and reused repeatedly.

[0006]

The inventors of the present invention have recovered crude PE.
As a result of extensive studies on the solvent for purifying the T resin, it was found that the foreign resin can be almost completely removed by eluting the crude PET resin with a specific solvent. That is, this particular solvent hardly dissolves the PET resin, but efficiently dissolves the foreign resin to be removed. At the same time, almost the entire amount of the above-mentioned specific solvent is recovered and is not lost to the outside of the purification treatment system, and can be used repeatedly many times.

<Specific solvent used in the method of the present invention> Examples of the specific solvent used in the method of the present invention include nuclear chlorine-substituted aromatic hydrocarbons or mixed solvents of aromatic hydrocarbons and organic carbonyl compounds.

<< Nuclear Chlorine-Substituted Aromatic Hydrocarbons >> Examples of the nuclear chlorine-substituted aromatic compounds include chlorobenzene, chlorotoluenes, chloroxylenes, o-dichlorobenzene, m-dichlorobenzene and dichloroxylenes.
Of these, chlorobenzene and o-dichlorobenzene are preferable.

<< Aromatic Hydrocarbons >> As aromatic hydrocarbons, benzene, toluene, mixed xylene, o-xylene, m-xylene, trimethylbenzene, diphenyl, methyldiphenyls, dimethyldiphenyls, ethyldiphenyls and diethyl. Examples thereof include diphenyls.
Among them, mixed xylene is preferable.

<< Organic Carbonyl Compound >> Examples of the organic carbonyl compound include methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, diisopropyl ketone, acetophenone, benzophenone, and diphenyl ketone. Of these, preferred are diethyl ketone, methyl isobutyl ketone and diisopropyl ketone.

Further, these solvents have a boiling point of 6 at normal pressure.
It is 0 ° C or higher, preferably 80 ° C or higher. The significance of this is that it is required to satisfy the requirement for environmental protection to realize a treatment in which these solvents are almost completely recovered and are not lost to the outside of the purification system.

<< Elution Conditions >> The amount of the solvent used for the elution depends on the amount of the mixed different resin, but in industrial practice, it is equivalent to 30 times the weight of the PET resin, preferably 3 times. It is usually sufficient to choose ~ 20 times the amount.

When a mixed solvent of an aromatic hydrocarbon and an organic carbonyl compound is used as an elution solvent, the mixing ratio of the two depends on the kinds of the aromatic hydrocarbon and the organic carbonyl compound used, but the former / the latter = 1. / 9 ~ 9/1
Is.

The elution of the foreign resin with the solvent can be carried out at room temperature, but in order to enhance the removal efficiency of the foreign resin, it is preferable to carry out the heating under heating, especially under reflux of the solvent. The elution time is not particularly limited as long as it is long enough to dissolve the different resin, but it is usually 3 min to 3 h, preferably 5 min to 2 h.

[0015]

EXAMPLES The purification method of the present invention will be specifically described below based on Examples. However, the present invention is not so limited.

[0016]

Example 1 PET resin (high density polyethylene 2.5 wt
2L (liter) of chlorobenzene was added to 200g of
Heated to reflux for 1 h. When the PET resin remaining on the filter plate was filtered while heating and dried, almost the theoretical amount of PET resin could be recovered. The elution time required for this purification was 1 h. When the filtrate was evaporated to dryness for further investigation, 5 g of a residue was obtained, and it was found that its identity was high-density polyethylene. Almost all of the chlorobenzene used for elution could be recovered.

[0017]

Example 2 To 200 g of PET resin (containing 2.5 wt% of polyvinyl chloride) was added 2 L of chlorobenzene, and the mixture was heated under reflux for 1 h. When the PET resin remaining on the filter plate after being filtered under heating was dried, the PET resin could be recovered in almost a theoretical amount. The elution time required for this purification was 1 h. When the filtrate was evaporated to dryness for further investigation, 5 g of a residue was obtained, and it was found that the true substance was polyvinyl chloride.
Almost all of the chlorobenzene used for elution could be recovered.

[0018]

Example 3 PET resin (high density polyethylene 2.5 wt
%) (Added to 2 g of mixed xylene / methyl isobutyl ketone = 1/1 (weight basis)) to 200 g
Heated to reflux. PE remaining on the filter plate after filtration under heating
When the T resin was dried, it was possible to recover the PET resin in an almost theoretical amount. The elution time required for this purification is 1 h
Met. When the filtrate was evaporated to dryness for further investigation, residue 5
g was obtained and it was found that its identity was high density polyethylene. Almost all the mixed solvent of mixed xylene / methyl isobutyl ketone = 1/1 (weight basis) used for elution could be recovered.

[0019]

Example 4 To 200 g of PET resin (containing 2.5 wt% of polyvinyl chloride), 2 L of a mixed solvent of mixed xylene / methyl isobutyl ketone = 1/1 (weight basis) was added and heated under reflux for 1 h. When the PET resin remaining on the filter plate after being filtered under heating was dried, the PET resin could be recovered in almost a theoretical amount. The elution time required for this purification was 1 h. When the filtrate was evaporated to dryness for further investigation, 5 g of a residue was obtained, and it was found that the true substance was polyvinyl chloride. Almost all the mixed solvent of mixed xylene / methyl isobutyl ketone = 1/1 (weight basis) used for elution could be recovered.

[0020]

According to the method of the present invention, the following various effects can be achieved together: (1) PET resin mixed with different resins can be applied in various forms from fine powder to agglomerates, and almost all different resins can be used. It can be removed completely and in a relatively short time. (2) To purify PET by separating the different resin almost completely and in a relatively short time even when the separation by mechanical means is difficult due to the fact that the PET resin is complexed with the different resin. You can (3) The solvent used for the purification process is almost completely recovered, and it is not possible to judge by the present lower limit of measurement whether or not there is an amount lost to the outside of the purification system.

Claims (10)

[Claims] 1. A thermoplastic polyester resin obtained by removing a resin other than the thermoplastic polyester by eluting and separating the thermoplastic polyester resin mixed with a resin other than the thermoplastic polyester resin with a solvent that does not dissolve the thermoplastic polyester resin. Purification method. 2. The method for purifying a thermoplastic polyester resin according to claim 1, wherein a nuclear chlorine-substituted aromatic hydrocarbon is used as the solvent. 3. The nuclear chlorine-substituted aromatic hydrocarbon used as a solvent is one or more selected from chlorobenzene, chlorotoluenes, chloroxylenes, o-dichlorobenzene and m-dichlorobenzene. A method for purifying the thermoplastic polyester resin as described. 4. The method for purifying a thermoplastic polyester resin according to claim 1, wherein a mixed solvent of an aromatic hydrocarbon and an organic carbonyl compound is used as the solvent. 5. When the solvent is a mixed solvent, the mixing ratio of the aromatic hydrocarbon and the organic carbonyl compound is the former / the latter =
The method for purifying a thermoplastic polyester resin according to any one of claims 1 to 4, which is in a range of 1/9 to 9/1. 6. An aromatic hydrocarbon constituting a solvent is benzene, toluene, xylenes, mixed xylene, trimethylbenzenes, diphenyl, methyldiphenyls, dimethyldiphenyls, ethyldiphenyls, diethyldiphenyls, isopropylbenzenes and The method for purifying a thermoplastic polyester resin according to claim 1, wherein the method is at least one selected from diisopropylbenzenes. 7. The organic carbonyl compound constituting the solvent is one or more selected from methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, diisopropyl ketone, acetophenone, benzophenone and diphenyl ketone. Method for refining thermoplastic polyester resin. 8. The method for purifying a thermoplastic polyester resin according to claim 1, wherein the solvent has a boiling point of 80 ° C. or higher at normal pressure. 9. The thermoplastic polyester resin according to claim 1, wherein the thermoplastic polyester resin is one or more selected from polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate isophthalate and polybutylene terephthalate isophthalate. Purification method. 10. The thermoplastic polyester resin according to claim 1, wherein the different resin mixed in the thermoplastic polyester resin is mainly one or more selected from polyethylene, polypropylene, polyvinyl chloride and polyvinylidene chloride. Purification method.