JPH01249842A - Regeneration of polyethylene terephthalate scrap contaminated by clorine-containing polymer - Google Patents

Abstract

PURPOSE: To reproduce a polyethylene terephtalate scrap contaminated with a polymer containing chloride in a usual polymer melting device by melting and mixing the scrap with a specified amount of an ethylene copolymer.

CONSTITUTION: (A) The scrap material of polyethylene terephtalate coated with the polymer containing chlorine and (B) 5-25 wt.% (% in the following), based on the composition (A), of the ethylene copolymer (ethylene/n-butyl acrylate/glycizilmetacrylate is suitable) containing B₁: 40-99.5% of ethylene, B₂: 0-40% of a compound of the formula (R₁ is a 1-8C alkyl R₂ is H, methyl, ethyl and B₃: 0.5-20% of a copolymerizable monomer having epoxy group (example; epoxy ester of an unsaturated organic acid, an epoxyether having vinyl or allyl group) are combined. Additive and reinforcing polymer with a low coefficient are preferably added and they are melted and mixed at 260-310°C.

COPYRIGHT: (C)1989,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION The present invention provides a method for the recovery and reuse of polyethylene terephthalate (PET) scrap coated with a chlorine-containing polymer, and Concerning useful articles.

Industrially useful for reuse, e.g. P
There is a large amount of PET scrap from sources such as ET bottles, fibers, and films.

PET requiring great impermeability to oxygen and water
Since the film and bottle are coated with a thin layer of chlorine-containing polymer, a significant amount of this scrap is difficult to use. This is usually a vinylidene chloride homopolymer, or vinylidene chloride and a small amount (approximately 0.1-101!) of another vinyl comonomer, which may or may not itself be chlorinated. The nature of their additional comonomers varies by manufacturer and is usually considered to be owned by the film coating industry.In addition, polyvinyl chloride, and vinyl chloride with small amounts of other unsaturated monomers. Copolymers with and can also be used in those applications. In addition, chlorine-containing polymers are used in photo
graphic) coated on a polyester film base. When vinylidene chloride polymer is used as the coating material, the amount of such coating is typically about 0.1-0.24 weight percent of the total weight of the coated polymer. However, this amount is not critical and can be adjusted as appropriate for the particular application. Typically, scrap material consisting of PET coated with chlorine-containing polymers cannot be used as is and must be boiled with sodium hydroxide or subjected to other chemical treatments to remove the polymer coating. For example, vinylidene chloride polymer is PE
It deteriorates at about 200°C, which is below the normal processing temperature of T.

If scrap P contains vinylidene chloride polymer
If ET is used inadvertently in processing, hydrogen chloride is released, resulting in PET degradation and decolorization and equipment corrosion. No practical melt processing method has so far been described that allows PET scrap contaminated with vinylidene chloride polymer or vinyl chloride polymer to be used without prior complete removal of chlorine-containing polymer contaminants. do not have.

It is thus easy to see that a method for recovering and reusing the millions of kilograms of such PET scrap material available each year would provide significant industrial benefits.

SUMMARY OF THE INVENTION In accordance with the present invention, a method for recovering and reusing chlorine-containing polymer coated polyethylene terephthalate scrap material comprises: -25% ethylene copolymer E/X/Y where E is a group formed from ethylene and constitutes about 40-99.5 weight percent of the ethylene copolymer; C-0-R.

where: R1 is an alkyl group having 1-8 carbon atoms, preferably 4-6 carbon atoms and most preferably 4 carbon atoms; R3 is hydrogen, methyl or ethyl, preferably hydrogen or methino and most preferably hydrogen; and X is about 0-40% by weight of the ethylene copolymer, preferably 15-
35 weight percent, and most preferably 20-
and Y consists of a copolymerizable epoxy ester of an unsaturated organic acid, an epoxy ether having a copolymerizable vinyl or allyl group, and a monoepoxy-substituted diolefin of 4 to 12 carbon atoms. a copolymerizable monomer containing an epoxy group selected from the group consisting of about 15-20 weight percent, preferably 10 weight percent, and most preferably 3-8 weight percent of the ethylene copolymer; and combine the combined polymeric materials with approximately 260
A method is provided herein consisting of melt mixing at a temperature of -310<0>C.

Additional comonomers such as CO and methyl acrylate can also be present in small amounts, provided that the physical and mechanical properties of the ethylene copolymer are not substantially altered. Below the lower end of the ethylene polymer range, it is hardly effective, while above the upper end it can be expected to result in excessive cross-linking of the system.

DETAILED DESCRIPTION OF THE INVENTION Preferred comonomers Y are selected from the group consisting of glycidyl methacrylate and glycidyl acrylate, and preferred ethylene copolymers E/X/Y are ethylene/n-butyl acrylate/glycidyl methacrylate terpolymers.

The ethylene copolymers used in the process of the invention are prepared by direct copolymerization, i.e. ethylene, epoxy group-containing monomers, at elevated temperatures and pressures in the presence of free radical polymerization initiators. -Y.

And, if present, it can be produced by copolymerization of the comonomer X described above. The polymerization temperature is preferably about 100-270°C, and most preferably,
130-230°C. Polymerization pressure is usually 70M
Pa, but preferably within the range of 140-350 MPa.

This copolymerization method, as well as copolymers of this type, are generally known and/or described in Sumitomo Chemical Co., Ltd. British Patent No. 1,352.088.

In addition to the E/X/Y copolymer described above, the polymer mixture may include a small amount, about 5-25 percent, based on total polymer weight, of a low modulus reinforcing polymer. Suitable reinforcing polymers are described in Epstein, US Pat. No. 4,172,859.

This patent is herein incorporated by reference. Typical reinforcing polymers are, for example, alternating or random copolymers of: ethylene/isobutyl acrylate/
Methacrylic acid terpolymer; ethylene/methyl acrylate/monoethyl maleate terpolymer and their 0-100% neutralized zinc, sodium, calcium, lithium, antimony, and potassium salts; and ethylene/vinyl acetate/-carbon oxide Terpolymer.

Scrap from PET coated with vinylidene chloride polymer and similar chlorine-containing polymers is produced at the same temperature as the original PET resin, i.e. from about 270°C to 310°C.
It is a thermoplastic material that can be processed at °C, eg, mixed, extruded, or injection molded.

Naturally, PET scrap obtained from commercial grade PET resin would be used. Mixing of the scrap materials can be carried out in any suitable commercial equipment, such as an extruder or mixer, but preferably at a barrel temperature such that the polymeric material is heated to a melting temperature of about 260 to 3100C. The process can be carried out in an extruder maintained at

The mixture of PET scrap material coated with chlorine-containing polymer is ethylene copolymer E/ according to the above definition.
When mixed with was found to be very surprising. The resulting fabricated article has acceptable mechanical properties for many applications and good barrier properties inherent to PET. Thus, they can be used for commercial purposes,
For example, it is suitable for use in various types of containers, and in particular in cans for solvent-based paints, as well as in film.

Additionally, approximately 0.05- based on the weight of the scrap material
Significant additional improvements are obtained when 1.0% of another additive, such as calcium carbonate, calcium stearate, other metal stearates, or hydrotalcite, is added to the mixture with the E/x/Y copolymer. It was discovered that it can be done.

Those other metal stearates shall be any metal stearate commonly available or used as lubricants, soaps, etc., such as zinc stearate, aluminum stearate, sodium stearate, potassium stearate, etc. Can be done. Hydrotalcite has the formula M g aAQz(OH)+5COs・4H20
It is a natural mineral with Instead of natural hydrotalcite, a slightly different formula Mg4.5A122 (OH
) rscOs·3.5H20 composites can be used as well. This synthetic material is available from Kyowa Chemical Industry Co., Ltd. (Osaka, Japan) under the name DHT-4A. Hydrotalcites, both natural and synthetic, can be calcined to remove the water of crystallization, if desired.

The invention is illustrated below by the following examples of some preferred embodiments thereof, in which all parts, proportions and percentages are by weight, unless otherwise stated: Example 1 PET scrap is 60:40 oriented and heat set, part of which is coated with a layer of vinylidene chloride copolymer, having an intrinsic viscosity of about 0.58, as measured in solution in a phenol/tetrachloroethane mixture of
It was a film made from E.T. The amount of vinylidene chloride copolymer was such that the chlorine content of the coated scrap material was 320 ppm.

This film is cut into small flakes, mixed with a second polymer, and molded using a Warner &amp;
Wernar & Pfleider
er) extruded from a twin-screw extruder to produce an extrudate, and the extrudate was cut into small pellets for further processing. The extruder was equipped with a vent. The melting temperature of the polymer was approximately 280°C. The pellets obtained from this process are injection molded at a molding temperature of about 40°C to form tumblers or tensile test bars.
ars). The tumbler was 94 mm high and had a diameter of 56 mm at the base and 70 mm at the top. The side walls as well as the bottom were 1.6 mm thick. The standard size test rod for this test is l/8 inch (3,
2 mm) and tested under standard conditions of ASTM D256.

Other polymers with which PET scrap materials are blended are ethylene/n-butyl acrylate/glycidyl methacrylate (67:28:5) copolymer (EBAG
MA) or ethylene/n-butyl (74:26) acrylate copolymer (EBA).
The latter was outside the scope of this invention. The strength of the injection molded tumbler is that it is equipped with an instrument at the bottom of the tumbler (
Measurements were made using an instrumented impact tester (modified Gardner (Q 3rdnet) impact). This measurement was performed using a 1.25 cm diameter impact penetration (pene).
trat 1on) shaft and a 6mm radius spherical point (
spherical paint) with an impact energy of 40 Joules. Failure of the sample was achieved by complete penetration of the impactor, and this required less energy than the impact energy. The results are summarized in the table below.

Composition % 75 None 25 0 3.985
None O1536,275 None
O2533,3 85320ppm C121500,2575320p
pmCQ25 0 0.1285 320p
pmCff O151, 375320ppmCQO
251,4 In this type of experiment, strength is considered acceptable when the instrumented impact value is greater than 1.0 Joules. However, it should be remembered that preferred embodiments of the invention include operation at reduced pressure, with the extruder vent connected to a vacuum source rather than to the atmosphere. Under those conditions, much higher impact values can be expected and a value of 1 joule would be considered unsatisfactory. These experiments in this example consisted of 15-25% E B A GMA
gives satisfactory strength when working with vinylidene chloride-containing PET scrap materials, but 15-25
% E/BA indicates that it does not provide satisfactory strength. Uncoated PET can be processed satisfactorily in both cases.

Example 2 In another set of tests for which test bars were made, when the extruder process stabilized (approximately 15 minutes), the off-gas from the extruder vent was injected into two gases containing O, IN sodium hydroxide. passed through an absorption trap. Gas was bubbled through the two traps for 25 minutes in both cases.

The contents of the trap were then analyzed for chlorine content by chromatography.

In experiments within the scope of the present invention, EBAGMA was
% level with PET scrap containing vinylidene chloride polymer. In a control experiment, the same scrap material was mixed with the E/BA copolymer at the same level. In both cases the chlorine content in the PET scrap was 660 ppm.

The experimental results are given in the table below.

Control 37 3531 Invention
157 1192 A significant reduction in the generated chlorine and an increase in the strength of the EBAGM stabilizes the system.
This shows the effect of A.

Example 3 The procedure of Example 1 was followed except that the vent of the extruder used to make the pellets was connected to a vacuum source and operated at a reduced pressure of about 10 kPa. In the first experiment,
There were no additives present in the mixture of PET scrap and EBAGMA. In a second experiment, this mixture was supplemented with a small amount of calcium stearate (technical grade, Fisher Scientific).
tific) and, in the third experiment, a small amount of DHT-4A (Kyowa Chemical Industry Co., Ltd.). In all experiments, the PET scrap material contained vinylidene chloride polymer in an amount such that the total chlorine content was 320 ppm. The results are shown below.

85 15 0 8.48
4.7 15 0.3(a) 3
6.784.7 15 0.3(b)
37.6 (a) Calcium Stearate (b) Synthetic Hydrotalcite Pelletization performed under reduced pressure, even in the absence of additives, provides significantly higher impact strength than when vented at atmospheric pressure (see Example 1). It can be seen that the following can be obtained. This improvement is further enhanced significantly by adding either calcium stearate or hydrotalcite to the mixture.

Patent Applicant E.I. du Pont de Nimoas & Co. Procedural Amendment May 26, 1988 Director General of the Patent Office Kunio Ogawa 1, Indication of Case 1988 Patent Application No. 70894 2, Invention Name 3: Relationship with the amended person's case Name of patent applicant E.I. Dupont de Nimoas &amp;
Company 5, date of amendment order None 6, scope of claims and detailed description of the invention in the specification subject to amendment (1)
) The specification and claims are corrected as stated in the attached sheet.

(2) The following statement is added under the 5th line from just below No. 23 of the specification (the line ``Additionally, the effect is further improved significantly.'').

rThe main features and aspects of the present invention are as follows.

(1) A method for recovering and reusing scrap material of polyethylene terephthalate coated with a chlorine-containing polymer, the scrap material being coated with a chlorine-containing polymer containing about 5-25% ethylene copolymer E based on the weight of the scrap material.
/X/Y where E is a group formed from ethylene and constitutes about 40-99.5 weight percent of the ethylene copolymer: X is CH2-C-C-0-R1 where: R , is an alkyl group having 18 carbon atoms; R1 is hydrogen, methyl or ethyl, and X is about 0-
and Y consists of a copolymerizable epoxy ester of an unsaturated organic acid, an epoxy ether having a copolymerizable vinyl or allyl group, and a monoepoxy-substituted diolefin of 4 to 12 carbon atoms. a copolymerizable monomer containing an epoxy group selected from the group consisting of about 0.5-20 weight percent of the ethylene copolymer, and the combined polymeric material contains about 260
A method consisting of melt mixing at a melt temperature of -310°C.

2. The method of paragraph 1 above, wherein R1 contains 4-6 carbon atoms.

3. The method of clause 2, wherein R contains 4 carbon atoms.

4. The method of claim 1, wherein Y is selected from the group consisting of glycidyl acrylate and glycidyl methacrylate.

5. The method of item 4 above, wherein the ethylene copolymer is a copolymer of ethylene, n-butyl acrylate, and glycidyl methacrylate.

6. The method of item 1 above, wherein R3 is hydrogen or methyl.

7. The method of item 6 above, wherein R1 is hydrogen.

8. The method of paragraph 1, wherein x constitutes 15-35 weight percent of the ethylene copolymer.

9. The method of paragraph 8, wherein X constitutes 20-35 weight percent of the ethylene copolymer.

10. The method of item 1 above, in which X does not exist.

11. The method of paragraph 1, wherein Y comprises 2-101 percent by weight of the ethylene copolymer.

12, Y is ethylene copolymer 3-8 jk bar'
The method of paragraph 11 above for structuring cents.

13. Approximately 0.05-1 based on the weight of scrap material
．． 0% calcium carbonate, calcium stearate,
2. The method of claim 1, wherein other metal stearates and additives selected from the group consisting of natural and synthetic hydrotalcites are also initially present in the mixture.

14. The method of paragraph 1, wherein about 5-25%, based on total polymer weight, of low modulus reinforcing polymer is also initially present in the mixture.

15. A polymer blend composition consisting essentially of polyethylene terephthalate scrap material coated with a chlorine-containing polymer, the scrap material comprising about 5-25% ethylene copolymer E based on the weight of the scrap material. /X/Y where: E is a group formed from ethylene and constitutes about 40-99.5 f[amount percent] of the ethylene copolymer: is an alkyl group having a carbon atom; R2 is hydrogen, methyl or ethyl, and X is about 0-
and Y consists of a copolymerizable epoxy ester of an unsaturated organic acid, an epoxy ether having a copolymerizable vinyl or allyl group, and a monoepoxy substituted diolefin of 4 to 12 carbon atoms. a copolymerizable heptamer comprising an epoxy group selected from the group consisting of about 0.5-20 weight percent of the ethylene copolymer.

16. The composition of item 15 above, wherein Rt contains 4-6 carbon atoms.

17. The composition of paragraph 16 above, wherein Rt comprises 4 carbon atoms.

18. The composition of item 15 above, wherein Y is selected from the group consisting of glycidyl acrylate and glycidyl methacrylate.

19. The composition of item 17, wherein the ethylene copolymer is a copolymer of ethylene, n-butyl acrylate, and glycidyl methacrylate.

20, R! 16. The composition of item 15, wherein is hydrogen or methyl.

21. The composition of item 20 above, wherein Rt is hydrogen.

22. The composition of paragraph 15 above, wherein X constitutes 15-35 weight percent of the ethylene copolymer.

23, wherein x constitutes 20-35 weight percent of the ethylene copolymer.

The composition of paragraph 15 above, wherein 246X is absent.

25. The composition of paragraph 15, wherein Y constitutes 2-1o weight percent of the ethylene copolymer.

26, the composition of paragraph 25 above, wherein Y constitutes 3-8 [L percent of the ethylene copolymer.

27, approximately 0.05-1 based on the weight of the scrap material
% of calcium carbonate, calcium stearate, other metal stearates, and natural and synthetic hydrotalcites.
Composition of item 5.

28. The composition of paragraph 15, wherein about 5-25% reinforcing polymer, based on total polymer weight, is also initially present in the mixture.

29. An article obtained by melt processing the composition of item 15 above.

30. An article obtained by melt processing the composition of item 19 above.

31. The article of item 29 above, which is a container or a film.

32. The article of item 30 above, which is a container or a film.

33. The article of item 32 above, which is a paint can. ” Appended Patent Claims ``1. A method for recovering and reusing scrap material of polyethylene terephthalate coated with a chlorine-containing polymer, comprising: -25% ethylene copolymer E/X/Y where E is a group formed from ethylene and constitutes about 40-99.5 weight percent of the ethylene copolymer; X is CH, -C-C -0-R1 where: R8 is an alkyl group having 1-8 carbon atoms; R1 is hydrogen, methyl or ethyl; 0-
and Y consists of a copolymerizable epoxy ester of an unsaturated organic acid, an epoxy ether having a copolymerizable vinyl or allyl group, and a monoepoxy substituted diolefin of 4 to 12 carbon atoms. and comprising about 5-20 weight percent of the ethylene copolymer, and the combined polymeric material has about 260%
A method consisting of melt mixing at a melt temperature of -310°C.

one? - A polymer blend composition consisting essentially of scrap material of polyethylene terephthalate coated with a 6 chlorine-containing polymer, the scrap material comprising about 5-25% ethylene copolymer E based on the weight of the scrap material. /X/Y where E is a group formed from ethylene and constitutes about 40-99.5 fU amount percent of the ethylene copolymer; is an alkyl group having carbon atoms of; R2 is hydrogen, methyl or ethyl; and X is about 0-
and Y consists of a copolymerizable epoxy ester of an unsaturated organic acid, an epoxy ether having a copolymerizable vinyl or allyl group, and a monoepoxy-substituted diolefin of 4 to 12 carbon atoms. a copolymerizable monomer comprising an epoxy group selected from the group consisting of about 0.5-20 weight percent of the ethylene copolymer. ”

Claims (1)

Claims: 1. A method for recovering and reusing scrap material of polyethylene terephthalate coated with a chlorine-containing polymer, comprising: 25% ethylene copolymer E
/X/Y where E is a group formed from ethylene and constitutes about 40-99.5 weight percent of the ethylene copolymer; R_1 is an alkyl group having 1-8 carbon atoms; R_2 is hydrogen, methyl or ethyl; and X is a group formed from about 0 of the ethylene copolymer.
-40% by weight; and Y is a copolymerizable epoxy ester of an unsaturated organic acid, an epoxy ether having a copolymerizable vinyl or allyl group, and a monoepoxy-substituted diolefin of 4 to 12 carbon atoms. and comprising about 0.5-20 weight percent of the ethylene copolymer, and the combined polymeric material has about 260%
A method consisting of melt mixing at a melt temperature of -310°C. 2. The method of claim 1, wherein R_1 contains 4-6 carbon atoms. 3. The method of claim 2, wherein R_1 contains 4 carbon atoms. 4. The method of claim 1, wherein Y is selected from the group consisting of glycidyl acrylate and glycidyl methacrylate. 5. The method of claim 4, wherein the ethylene copolymer is a copolymer of ethylene, n-butyl acrylate, and glycidyl methacrylate. 6. The method according to claim 1, wherein R_2 is hydrogen or methyl. 7. The method according to claim 6, wherein R_2 is hydrogen. 8. The method of claim 1, wherein X constitutes 15-35 weight percent of the ethylene copolymer. 9. The method of claim 8, wherein X constitutes 20-35 weight percent of the ethylene copolymer. 10. The method according to claim 1, wherein X is absent. 11. The method of claim 1, wherein Y constitutes 2-10 weight percent of the ethylene copolymer. 12. The method of claim 11, wherein Y constitutes 3-8 weight percent of the ethylene copolymer. 13. Approximately 0.05-1 based on the weight of scrap material
．． 0% calcium carbonate, calcium stearate,
2. The method of claim 1, wherein other metal stearates and additives selected from the group consisting of natural and synthetic hydrotalcites are also initially present in the mixture. 14. The method of claim 1, wherein about 5-25%, based on total polymer weight, of low modulus reinforcing polymer is also initially present in the mixture. 15. A polymer blend composition consisting essentially of polyethylene terephthalate scrap material coated with a chlorine-containing polymer, the scrap material comprising about 5-25% ethylene copolymer E based on the weight of the scrap material. /X/Y where E is a group formed from ethylene and constitutes about 40-99.5 weight percent of the ethylene copolymer; R_1 is an alkyl group having 1-8 carbon atoms; R_2 is hydrogen, methyl or ethyl; and X is about 0 of the ethylene copolymer.
-40% by weight; and Y is a copolymerizable epoxy ester of an unsaturated organic acid, an epoxy ether having a copolymerizable vinyl or allyl group, and a monoepoxy-substituted diolefin of 4 to 12 carbon atoms. a copolymerizable monomer containing an epoxy group selected from the group consisting of: and comprising about 0.5-20 weight percent of the ethylene copolymer. 16. The composition of claim 15, wherein R_1 contains 4-6 carbon atoms. 17. The composition of claim 16, wherein R_1 contains 4 carbon atoms. 18. Claim 1 in which Y is selected from the group consisting of glycidyl acrylate and glycidyl methacrylate.
Composition according to item 5. 19. The composition of claim 17, wherein the ethylene copolymer is a copolymer of ethylene, n-butyl acrylate, and glycidyl methacrylate. 20. The composition according to claim 15, wherein R_2 is hydrogen or methyl. 21. The composition according to claim 20, wherein R_2 is hydrogen. 16. The composition of claim 15, wherein 22, X constitutes 15-35 weight percent of the ethylene copolymer. 23. The composition of claim 22, wherein X constitutes 20-35 weight percent of the ethylene copolymer. 24. The composition according to claim 15, wherein X is not present. 25. The composition of claim 15, wherein Y constitutes 2-10 weight percent of the ethylene copolymer. 26. The composition of claim 25, wherein Y constitutes 3-8 weight percent of the ethylene copolymer. 27, approximately 0.05-1 based on the weight of the scrap material
16. The composition of claim 15, comprising % of calcium carbonate, calcium stearate, other metal stearates, and additives selected from the group consisting of natural and synthetic hydrotalcites. 28. The composition of claim 15, wherein about 5-25% reinforcing polymer, based on total polymer weight, is also initially present in the mixture. 29. An article obtained by melt processing the composition according to claim 15. 30. An article obtained by melt processing the composition according to claim 19. 31. The article according to claim 29, which is a container or a film. 32. Claim 30 which is a container or a film
Items listed in section. 33. The article according to claim 32, which is a paint can.