JPH0892411A - Recovery of polyolefin - Google Patents

Abstract

PURPOSE: To recover polyolefin from a laminate made of a polyolefin and foreign materials in such a manner that the recovered polyolefin is less deteriorated in properties and is less contaminated with foreign materials. CONSTITUTION: Polyolefin is recovered by adding water to 100 pts.wt. laminate made of a polyolefin layer and a foreign material layer selected from among water-soluble foreign substances and hydrolyzable foreign materials, placing the mixture in a pressure vessel, blowing an inert gas into the vessel, heating the entire to 200-400 deg.C to increase the pressure inside the vessel to 150-250kg/cm<2> G to thereby separate the mixture into a water phase and a polyolefin phase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering a recyclable polyolefin from a laminate of a polyolefin and a resin other than the polyolefin, such as polyethylene terephthalate, polyamide or the like or pulp paper.

[0002]

2. Description of the Related Art Polyolefins such as polyethylene and polypropylene are currently used as various packaging materials, various containers such as bottles, bumpers and toys. In addition to being used alone as a polyolefin, recently, in order to impart functionality to a molded article, it is generally compounded with another resin, for example, a resin other than polyolefin such as polyester or polyamide. ing.

For example, a coated bumper having a polypropylene bumper core material coated with a weather-resistant coating, a laminate of a low density polyethylene film melt-laminated on the surface of a printed pulp paper, nylon 6 and super Gasoline tank made of laminate with high molecular weight high density polyethylene, bag for retort pouch with heat seal layer of low density polyethylene or ethylene / vinyl acetate copolymer on printed polyethylene terephthalate film, ethylene / polyvinyl alcohol copolymer weight It is a laminate of a polyolefin such as an anti-fog film, which is a laminate of a united body and polyethylene, and other foreign matter.

Conventionally, these laminates are burned as they are, or they are once crushed and then melted by a reclaiming extruder so that the appearance of pasture fences, sleepers, U-grooves, piles, etc. does not pose any problem. It was regenerated into a product (USP4008858, US
P3788567, USP3748074). It has also been proposed that the resin-laminated product be cracked (pyrolysis) and recovered as crude gasoline.

Recently, expanded polystyrene paper trays,
Polyethylene terephthalate bottles have been collected and crushed and recycled. However, this is a plain material and does not consist of different kinds of resins. As a method of recovering a polyolefin from a different kind of material, in a plastic product whose surface is coated in JP-A-2-273207, the coated surface of the plastic product is coated with a soft abrasive (peach, walnut,
Cone, thermosetting plastic) to remove the paint pigment on the painted surface by direct pressure plasting, then crush and wash the plastic product from which the paint pigment has been peeled off, and color and melt it to remold it. Although a method for recycling treated painted plastic products is disclosed, this method cannot completely remove the coating on the surface of polypropylene pallets, containers, etc. Limited to

Further, Japanese Patent Laid-Open No. 6-106536 discloses that
A method for separating and removing a resin coating film from a plastic molded article having a resin coating film formed on the surface thereof, and collecting the plastic molded article as a materialized plastic material, comprising: A step of crushing each small piece to be treated, a step of applying a compressive impact force based on micro-vibration to crush each of the individual small pieces to be treated, or a compressive impact force based on micro-vibration Adding and crushing, removing the resin coating film peeled by crushing at any time, a step of re-grinding each crushed small piece to be treated,
A step of applying impact milling force to each of the re-pulverized individual pulverized pieces for polishing and sizing, the sizing that has been sizing, and the resin coating film separated by the sizing. The present invention proposes a method for crushing a plastic molded product, separating a resin coating film, and sizing a plastic material, which includes at least a step of separating the resin coating film and the like.

This method has a drawback that the efficiency of separating the coating film from the plastic material is low. Furthermore, Japanese Patent Laid-Open No. 5-2
No. 71328 discloses a hydrolyzable polymer in a mixture of a hydrolyzable polymer such as polyamide and polyethylene terephthalate and a non-hydrolyzable polyolefin, using 1 to 20 volumes of water relative to polymer 1. Two
A method of hydrolyzing a hydrolyzable polymer to make it water-soluble under the pressure of steam generated by heating to a temperature of 00 to 350 ° C., separating a water phase, and recovering a polyolefin is proposed. However, the polyolefin recovered by this method cannot be reused because it is highly deteriorated during the reaction process, and is limited to use as a raw material for chemical recycling.

Further, Japanese Patent Laid-Open No. 6-198652 discloses that
While crushing a plastic molding having a part or all of its surface coated and melt-kneading this with a kneader,
0.5 to 50 parts by weight of water and 0.
001 to 3 parts by weight of coating film decomposition accelerator and 200 to 320 ° C.
After contacting at the temperature of 0.5 to 5 minutes, the opening 10
A method for treating a coated plastic molded body has been proposed, which is characterized by filtering with a metal mesh filter of 120 μm. This method is intended to prevent deterioration of the physical properties of the recycled product, but does not positively separate the coating film from the plastic molded body.

[0009]

DISCLOSURE OF THE INVENTION The present invention is to decompose, dissolve or disintegrate a resin other than polyolefin from a polyolefin laminate containing a resin other than polyolefin and other materials as a foreign substance, without degrading the polyolefin. It is an object of the present invention to provide a method for recovering a reusable polyolefin by separating and removing the polyolefin.

[0010]

DISCLOSURE OF THE INVENTION The present invention is a laminate of a polyolefin layer (A) and a layer (B) of a foreign substance other than polyolefin selected from water-soluble foreign substances or hydrolyzable foreign substances (B). 100 to 1000 parts by weight of water is added to the above, and this is put into a pressure resistant container, and then an inert gas is filled in the pressure resistant container, and then heated to 200 to 400 ° C., thereby the pressure in the pressure resistant container is 150 to 250 kg / cm ² G
By separating it into an aqueous phase and a polyolefin phase,
Then, a method for recovering a polyolefin is provided, which comprises recovering a polyolefin.

[0011]

The foreign matter of the polyolefin laminate is dissolved in water, hydrolyzed and dissolved in water to separate into a water phase and a polyolefin phase, so that the polyolefin can be easily recovered. Further, the presence of the inert gas prevents the deterioration of the polyolefin.

(Outline of the Invention) The polyolefin of one layer constituting the polyolefin laminate is a water-insoluble, non-hydrolyzable resin, and specifically, high density polyethylene, linear low density polyethylene, high pressure polyethylene Method ethylene resins such as low density polyethylene; propylene homopolymer, propylene / ethylene copolymer, propylene / ethylene / butene-1 copolymer, propylene / butene-1 copolymer, propylene-4-methylpentene-1 Propylene-based resins such as copolymers and propylene-3-methylpentene-1 copolymers; poly (4-methylpentene-1),
Examples thereof include poly (butene-1). These polyolefins may be used alone or in combination of two or more.

As the water-soluble or hydrolyzable foreign matter which constitutes another layer together with the foreign matter polyolefin layer, pulp paper, thermoplastic polyester such as cellulose, polyethylene terephthalate and polybutylene terephthalate, nylon 6, nylon 6, nylon 6,6, Examples thereof include polyamides such as nylon 6,10, nylon 6,12 and nylon 12, polycarbonate, polyacrylonitrile, polyurethane, alkyd resin, oil-modified alkyd resin, melamine resin, polyphenylene ether resin, polyether polyketone resin and the like.

For example, polyethylene terephthalate is hydrolyzed into water-insoluble terephthalic acid and water-soluble ethylene glycol. If water is made alkaline and sodium terephthalate is used, this too dissolves in water. Cellulose and pulp paper are hydrolyzed into water-soluble glucose. Nylon 6 is hydrolyzed to adipic acid and hexamethylenediamine.

The processing apparatus processing device 1 is pressure-resistant vessel 2 as shown in FIG. 1, the lid 3, stirring blade 4, the water supply pipe 5, the inert gas supply pipe 6, heater 7, water drain pipe 8, thermometer 9, Filter 10, valve 11, 1
2, 13, an air pressure adjusting valve 14, and a barometer 15. In the figure, 16 is a dispersion liquid.

Treatment method The laminate is preliminarily prepared to have a thickness of 2 to 100 mm, preferably 10 mm.
It is cut or crushed into small pieces having a size of ˜50 mm, and the pieces are put into the pressure resistant container 2. Then, after closing the lid 3, an inert gas such as nitrogen, argon, helium, carbon dioxide gas is supplied into the pressure-resistant container 2 through the supply pipe 6, and oxygen in the container is discharged.
Replace with an inert gas. Then, water is supplied from the water supply pipe 5 into the pressure resistant container. The water is preferably neutral, but depending on the type of foreign matter, it is made alkaline by adding caustic soda, sodium carbonate or the like, or acidified by adding acetic acid, hydrochloric acid or the like.
The mixing ratio of water and the laminate is a volume ratio, and the ratio of water to the laminate 1 is 1 to 10, preferably 1.5 to 5.

Then, the valve 11 is closed, an inert gas is supplied into the pressure-resistant container and pressurized, and the container is heated by a heater so that the temperature in the pressure-resistant container is 200 to 400 ° C., preferably 220 to 350 ° C. The pressure inside the pressure vessel is 150 to 25
0 kg / cm ² G, preferably 170 to 230 kg / c
Adjust to m ² G. Temperature less than 200 ° C, pressure 150
If it is less than kg / cm ² G, the separation is not sufficiently performed. or,
If the temperature exceeds 400 ° C, the physical properties of the polyolefin change greatly, or the polyolefin is thermally decomposed. The heating / pressurizing time depends on the type of foreign matter, the wall thickness, the capacity of the laminate, etc., but 1 minute to 3 hours, preferably 2 to 60 minutes is sufficient.

[0018]

EXAMPLES The present invention will be specifically described with reference to the following examples. Example 1 As a laminate, polyethylene terephthalate (thickness 25
μm), MFR 8 g / 10 min, density 0.918 g / c
A retort pouch bag made of a laminated body of m ³ linear low-density polyethylene (thickness 40 μm) was crushed at −72 ° C., and 2
It was a small piece of 10 mm.

After putting 0.1 kg of this small piece into a pressure-resistant container having a capacity of 2 liters and closing the lid, 0.2 kg of pH 7 water was supplied into the pressure-resistant container, and then the valve was closed to stop the water supply. Then, nitrogen gas was supplied into the pressure vessel to increase the pressure in the pressure vessel to 50 kg / cm ² G. Then, the pressure-resistant container was heated to 300 ° C. under stirring, the pressure in the pressure-resistant container was increased to 200 kg / cm ² G, and then kept at the same temperature and the same pressure for 2.5 minutes. Then, the heating was stopped, the temperature was lowered to 30 ° C., the pressure regulating valve was opened, the pressure inside the pressure resistant container was returned to atmospheric pressure, and then the water drain valve was opened to separate the water phase.

The solid content (linear low density polyethylene) in the pressure vessel was taken out and dried with hot air at 90 ° C.
Heat press molding was performed at 210 ° C. and 100 kg / cm ² , and
A 1 mm sheet (Sample 1) was obtained. On the other hand, the pulverized product of the laminate was melt-kneaded at 240 ° C., then extruded into a strand and cut to obtain pellets. 210 this
0.1mm after hot press molding at 100 ℃ / 100kg / cm ²
Sheet (Sample 2) was obtained.

The infrared absorption spectra of both Samples 1 and 2 were taken, and the two were compared to determine the amount of polyethylene terephthalate remaining in Sample 1, which was 5% by weight. Therefore, it is understood that 95% by weight of polyethylene terephthalate was separated from the laminate. As a blank experiment, MFR 8g / 10 minutes, density 0.91 was used instead of the laminate.
Using linear low density polyethylene powder of 8 g / cm ³ and treating with water in a pressure resistant container under the same conditions as above, and determining its MFR and density, MFR 8 g / 10 min,
No change in physical properties was observed at a density of 0.918 g / cm ³ .

The weight of the recovered linear low density polyethylene was the same as the weight put in the pressure vessel. Therefore, the weight reduction rate was 0%. Furthermore, when the amount of insoluble matter that withstands hot orthodichlorobenzene of the recovered linear low-density polyethylene was determined, the amount of insoluble matter produced by heating / pressurizing with water was 1% by weight.

Example 2 In Example 1, the pressure vessel conditions were 380 ° C. and 250 ° C.
The laminate was treated in the same manner except that the holding time was changed to kg / cm ² G and the holding time was 1.5 minutes. The polyethylene terephthalate removal rate was 95%, and the weight reduction rate of the recovered linear low density polyethylene was 3%. The insoluble matter formed was 35% by weight.

Example 3 In Example 1, the pressure vessel conditions were 250 ° C. and 20 ° C.
The linear low density polyethylene was recovered in the same manner except that the holding time was 0 kg / cm ² G and the holding time was 5 minutes. The results are shown in Table 1.

Comparative Example 1 In Example 1, the temperature was 123 ° C. and the pressure was 1.2 kg / c.
m ² G, where addition to the retention time 30 minutes have been processed laminate in the same manner, the removal rate of polyethylene terephthalate is 2%, 0 weight reduction rate of the recovered linear low density polyethylene%, generation The insoluble content was also 0%.

Comparative Example 2 The laminate was treated under the conditions shown in Table 1 in the same manner as in Example 1 except that pressurization with nitrogen gas was not performed.

Examples 4 to 5 and Comparative Example 3 As a laminate, on the surface of a polypropylene bumper core material,
Polypropylene was recovered in the same manner as in Examples 1 and 2 or Comparative Example 1 except that a crushed product of an automobile bumper coated with a urethane paint having a thickness of 3 μm was used. The results are shown in Table 1.
Shown in.

Examples 6 to 7 and Comparative Example 4 As a laminate, ultra high molecular weight high density polyethylene (1 m
m) / maleic anhydride (0.8% by weight) grafted low density polyethylene (12 μm) / nylon 6 (20 μm) /
Maleic anhydride grafted low density polyethylene (12μ
m) / ultra high molecular weight high density polyethylene (1 mm), which was treated in the same manner as in Examples 1 and 2 or Comparative Example 1 except that a pulverized product of a gasoline tank was used. The high molecular weight high density polyethylene was recovered. The results are shown in Table 1.

Examples 8 to 9 and Comparative Example 5 As a laminate, a pulp paper having a basis weight of 150 g / m ² was gravure-printed on the surface, and the surface of the adhesive was treated with ozone, MI 4 g / 10 minutes, Density 0.922g / c
m ³ low density polyethylene extruded film at 290 ° C (2
00 μm) is used to obtain a laminated film,
Others were treated in the same manner as in Examples 1 and 2 or Comparative Example 1 to recover low density polyethylene. The results are shown in Table 1.

Comparative Example 6 In Example 4, a pulverized product of the urethane coating film / polypropylene laminate (coating bumper) was fed to an extruder and melt-kneaded at 280 ° C. Water was supplied from a supply pipe provided in the middle of the extruder to 100 parts of the laminated body at a ratio of 10 parts by using a pressure pump, and then retained in the extruder for 1 minute at a temperature of 280 ° C. 200k
It was extruded into strands at a pressure of g / cm ² , cooled in water, and cut into pellets. The results are shown in Table 1.

[0031]

[Table 1]

[0032]

EFFECTS OF THE INVENTION The polyolefin can be recovered from the laminate without deteriorating the physical properties and reducing the contamination rate of foreign matters.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an apparatus used to carry out a recovery method of the present invention.

[Explanation of reference numerals] 1 processing device 2 pressure-resistant container 3 lid 4 stirring blade 5 water supply pipe 6 inert gas supply unit 7 heater

Claims (2)

[Claims] 1. 100 to 1000 parts by weight of water in 100 parts by weight of a laminate of a polyolefin layer (A) and a layer (B) of a foreign material other than a polyolefin selected from water-soluble and hydrolyzable foreign materials. In addition, after putting this in a pressure resistant container and then filling an inert gas in the pressure resistant container,
The pressure in the pressure vessel is increased to 15 by heating to 400 ° C.
A method for recovering a polyolefin, which comprises separating the aqueous phase and the polyolefin phase by setting the amount to 0 to 250 kg / cm ² G, and then recovering the polyolefin. 2. The method according to claim 1, wherein pH of water is acidic or alkaline.