JP2000037673A - Method for classifying and recovering laminated material for packing food - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently separate and recover a paper, a thermoplastic resin and aluminum foil being constitutional materials of a used paper pack container to easily regenerate them and to recycle even a solvent used in separation and recovery to use the same. SOLUTION: An empty container of a paper pack container for packing food comprising cardboard/thermoplastic resin or cardboard/thermoplastic resin/ aluminum foil is heated in an aromatic solvent with a solubility parameter of 8.5-9.3 (ST3) to remove paper or paper/aluminum foil (ST4) and, after the solvent containing a thermoplastic resin is cooled to 10 deg.C or lower (ST5), the thermoplastic resin in the solvent is filtered and isolated or the solvent is distilled to separate the thermoplastic resin and the solvent and, further, the solvent from which the thermoplastic resin is removed is used with respect to the removed paper or paper/aluminum foil to repeat heating/cooling/filtering or distillation treatment (ST3-ST7) to isolate and recover paper/thermoplastic resin/solvent or paper/thermoplastic resin/aluminum foil/solvent (ST8).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin laminated on the surface of paper and paper as a substrate from an empty container after use of a paper packaging container made of paper, and a thermoplastic resin layer. The present invention relates to a method for separating and recovering a laminated material for food packaging that separates and recovers an aluminum foil laminated thereon and facilitates reuse of each material.

[0002]

2. Description of the Related Art Conventionally, as a container for packaging foods such as milk, juice, coffee, sake (for drinking and seasoning), liquids such as yogurt, jelly and miso, and semi-solid substances (including sol-gel type). , Paper pack containers are used. This paper pack container is generally provided with a thermoplastic resin layer such as polyethylene or polypropylene on both the inner and outer surfaces of a paper base material (paperboard), and depending on the contents (especially sake), an aluminum foil is further provided on the inner thermoplastic resin layer. It is a laminated structure provided. In such a laminated structure of the paper pack container, since the paper and the thermoplastic resin such as polyethylene and polypropylene, and even the aluminum foil are adhered to each other, the used container is replaced with the constituent materials (paper, thermoplastic resin). , Aluminum foil) is difficult to separate and recover, and most are incinerated.

[0003] However, due to the fact that resources are required to be reused in recent years, the following recovery methods have been performed. A method in which paper and a thermoplastic resin are mechanically peeled to separate an aluminum foil. A method of separating a paper and a thermoplastic resin by dissolving the water-soluble compound layer by immersing an empty paper pack container in water with a water-soluble compound layer interposed between the bonding surfaces of the paper and the thermoplastic resin. After washing the empty container of the collected paper pack container, it is cut into any shape and stirred in warm water. From the mixture of paper and thermoplastic resin loosened, it takes time to form paper (pulp). A method for separating a thermoplastic resin.

[0004]

However, all of the above-mentioned recovery methods have the following problems a to d. a) The processing time required to separate and recover paper and thermoplastic resin from used empty containers is long. b) It is difficult to treat wastewater generated in the regeneration step. c) The paper adheres again to the separated thermoplastic resin such as polyethylene, and it is difficult to completely separate the paper and the thermoplastic resin. d) Depending on the type of release control agent, water-soluble thermoplastic resin, alkali-soluble resin, etc. used for recovery, it cannot be used as a food packaging material from the viewpoint of safety, and there are restrictions.

The present invention has been made in view of such problems a to d, and efficiently separates and recovers paper, thermoplastic resin, and aluminum foil, which are constituent materials of used paper pack containers, It is an object of the present invention to provide a method for facilitating regeneration and recycling a solvent used for separation and recovery.

[0006]

According to a first aspect of the present invention, there is provided a method for separating and recovering a laminated material for food packaging, comprising the steps of: A paper pack container for food packaging provided with a resin layer,
Alternatively, an empty container of a food packaging paper pack container further provided with aluminum foil on the inner surface of the thermoplastic resin layer is heated in an aromatic solvent having a specific solubility parameter (solubility parameter). And paper / thermoplastic resin or paper / thermoplastic resin / aluminum foil from the wastewater, and the solvent is recycled.

According to a second aspect of the present invention, there is provided a method of separating and recovering a laminated material for food packaging, wherein a paper pack container for food packaging having a thermoplastic resin layer provided on at least the inner surface of the inner and outer surfaces of the paper base material, or the inner surface. The empty container of the paper pack container for food packaging further provided with an aluminum foil on the thermoplastic resin layer of above is heated from 100 ° C. in an aromatic solvent having a solubility parameter (solubility parameter) of 8.5 to 9.3. It is characterized by heating in a temperature range up to the boiling point of the solvent, separating and recovering paper / thermoplastic resin or paper / thermoplastic resin / aluminum foil from the solvent, and recycling the solvent.

Further, in the method for separating and recovering a laminated material for food packaging according to claim 3, a paper pack container for food packaging, wherein a thermoplastic resin layer is provided on at least the inner surface of the inner and outer surfaces of the paper substrate, or the inner surface. The empty container of the paper pack container for food packaging further provided with an aluminum foil on the thermoplastic resin layer of above is heated from 100 ° C. in an aromatic solvent having a solubility parameter (solubility parameter) of 8.5 to 9.3. Heating in the temperature range up to the boiling point of the solvent, removing paper or paper / aluminum foil from the solvent, cooling the solvent containing the thermoplastic resin after removal to 10 ° C. or less,
By filtering and isolating the thermoplastic resin in the solvent, or by distilling the solvent and separating the thermoplastic resin and the solvent to remove the thermoplastic resin, paper / thermoplastic resin or paper /
It is characterized by separating and recovering thermoplastic resin and aluminum foil and recycling the solvent.

[0009] In the separation and recovery method according to claims 1 to 3,
In each case, an empty container of a paper base material, a paper pack container made of a thermoplastic resin, or a paper base material made of a paper base material, a thermoplastic resin, and an aluminum foil is heated in an aromatic solvent. The thermoplastic resin or paper, the thermoplastic resin, and the aluminum foil are separated, and the paper or the paper / aluminum foil remains in the solvent in a separated state, and the thermoplastic resin is dissolved in the solvent. Therefore, at this point, the paper or paper / aluminum foil and the thermoplastic resin can be separated.

Here, the solvent has a solubility parameter (solubility parameter) of 8.5 to 9.3, but a solvent having a solubility parameter other than 8.5 to 9.3 does not dissolve the thermoplastic resin, Many of them swell slightly or have no effect, and the boiling points are not in an appropriate range, so that the balanced separation and recovery treatment as in the present invention cannot be performed.
The heating temperature is in the range from 100 ° C. to the boiling point of the solvent.

Since the thermoplastic resin is dissolved in the solvent from which the paper or the paper / aluminum foil has been removed, to separate the thermoplastic resin from the solvent, specifically, as in claim 3, Do. That is, when the solvent containing the thermoplastic resin is cooled to 10 ° C. or less, the thermoplastic resin is suspended in the solvent. Therefore, if the solvent is filtered or distilled, the thermoplastic resin can be separated (hereinafter, referred to as the solvent). , The processing up to this point is referred to as primary processing).

Since a small amount of thermoplastic resin often adheres to the paper or paper / aluminum foil (particularly paper) removed first, the separation accuracy between the paper or paper / aluminum foil and the thermoplastic resin is increased. For this purpose, the configuration of claim 4 is performed. That is, for the paper or paper / aluminum foil removed by the heat treatment in the primary treatment, using the solvent from which the thermoplastic resin has been removed (the solvent recovered after the primary treatment), the heating / cooling / filtration or distillation treatment (primary treatment) (The same processing as the processing) is repeated (hereinafter, this is referred to as secondary processing), thereby increasing the separation accuracy of paper, thermoplastic resin, solvent or paper, thermoplastic resin, aluminum foil, solvent, and paper, thermoplastic resin, Solvent or paper, thermoplastic resin, aluminum foil and solvent can be completely isolated and recovered.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. FIG. 1 shows a process diagram of a method for separating and collecting a laminated material for food packaging according to an embodiment. First, in step (hereinafter abbreviated as ST) 1, an aromatic solvent is prepared.
This solvent has a solubility parameter (solubility parameter)
8.5 to 9.3, for example, toluene (boiling point 111
℃), xylene (ortho, meta, para, boiling point about 1
40 ° C.), ethylbenzene (boiling point 136 ° C.), or a mixture thereof. The amount of the solvent to be used is 5 to 20 times, preferably 5 to 15 times the weight of the paper pack container.

As described above, the paper pack container to be charged into the solvent is used for packaging foods such as liquids and semi-solids, and heat is applied to at least the inner surface of the inner and outer surfaces of the paper base material (paperboard). It is provided with a thermoplastic resin layer, or further provided with an aluminum foil on the inner surface of the thermoplastic resin layer. The empty container of this paper pack container is washed and dried and collected.
Prepare this as it is or cut it finely.

After charging an empty paper pack container into the solvent (S
T2) by heating the solvent at a temperature between 100 ° C. and the boiling point of the solvent (see above) with gentle stirring, or by heating while circulating the solvent (ST3).
In about 20 to 60 minutes, the thermoplastic resin layer provided on the inner and outer surfaces of the paper pack container breaks and separates from the paperboard. When an aluminum foil is provided on the inner surface, the aluminum foil is also separated from the thermoplastic resin layer. That is, by the heat treatment, the paper or the paper / aluminum foil floats in the solvent, and most of the exfoliated thermoplastic resin is dissolved or finely dispersed in the solvent.

At this time, the adhesive portions on the bottom and side surfaces of the paper pack container are completely peeled off. When the recovered empty container is heated in a solvent, it is also effective to put the empty container in a basket-shaped container or net that is not affected by the solvent, or to move the basket-shaped container or net during the heating process. It is. Next, the solvent after the heat treatment is removed, the paper and the aluminum foil are dried under normal pressure or reduced pressure, and the paper or the paper / aluminum foil is taken out (removed) (ST4). The solvent from which the paper or the paper / aluminum foil has been removed is cooled to 10 ° C. or lower (ST5). Then, the thermoplastic resin dissolved in the solvent precipitates, and the deposited thermoplastic resin floats in the solvent. If this solvent is filtered (ST6), the thermoplastic resin can be separated and removed from the solvent (ST7). If the color of the solvent after filtration and separation is remarkable, the solvent after filtration and separation is purified by distillation under normal pressure or reduced pressure to remove the color of the solvent. Of course, in addition to filtration, the thermoplastic resin may be separated and removed from the solvent by distillation. The primary processing ends here.

Thereafter, a series of heating / cooling / filtration or distillation processes (ST3 to ST7) are similarly performed on the paper or paper / aluminum foil recovered in ST4 during the primary treatment using the solvent recovered by filtration or distillation. (Secondary processing). This makes it possible to recover the thermoplastic resin adhered to the paper or paper / aluminum foil (especially paper) recovered in the primary treatment and the thermoplastic resin remaining in the solvent recovered after the primary treatment. As a result, the separation accuracy of paper / thermoplastic resin / solvent or paper / thermoplastic resin / aluminum foil / solvent is increased, and paper / thermoplastic resin / solvent or paper / thermoplastic resin / aluminum foil / solvent is completely isolated. It can be collected (ST8). It should be noted that the secondary processing is usually sufficient once, but may be repeated several times (about two to three times) as necessary.

The paper or paper / aluminum foil recovered by the secondary treatment is dried under reduced pressure, and the adhering solvent is removed and recovered. The solvent after the secondary treatment is collected and provided for recycling.
Thus, according to this separation and collection method, unlike the conventional method of crushing an empty paper pack container finely and collecting the cellulose fiber and the thermoplastic resin, the paper pack container can be processed and separated in a plate shape, There is no mixing of paper fibers in the recovered thermoplastic resin, and a pure material suitable for reuse can be recovered.

Next, specific examples will be described. [Example 1] 100 g of paper packs (including bottom and side adhesive portions) were washed with water and dried from each of the milk packs of Company A, Company B, Company C, and Company D, and were subjected to a backflow cooler and solvent circulation. It was placed in a container for paper pack processing equipped with an apparatus, and 1000 g of o-xylene was added as a solvent to this, and heated to 120 ° C. while circulating the solvent. In 15 to 20 minutes, the coating of the thermoplastic resin was finely broken and peeled off from the paperboard, and a part of the broken and peeled coating was apparently dissolved and dispersed in the solvent. After the heat treatment, the solvent was quickly put into another container, and the paper was removed from the solvent.

The solvent placed in a separate container was cooled to 10 ° C., and the precipitate was removed from the solvent by distillation under reduced pressure to separate the solvent and the thermoplastic resin (primary treatment). The solvent recovered after the primary treatment was transferred back to the container for paper pack treatment, and the same operation as the primary treatment was repeated (secondary treatment). The paper and thermoplastic resin after the secondary treatment were dried under reduced pressure. All recoverable solvents were recovered. As a result of performing this series of collection processing, the data after each processing for each paper pack container is as shown in Table 1 below.

<Table 1> Type Recovered paper (g) Recovered resin (g) Total (g) Company A product 84.1 15.8 99.9 Company B product 82.8 17.0 99.8 Company C product 80.5 19.4 99.9 D company's product 81.3 18.8 100.1 Solvent recovery rate (after secondary treatment) 97.5% The recovered paper according to this Example 1 is white and smooth, and paper pack The adhesive parts on the bottom and side surfaces of the were completely peeled off. [Example 2] Each of the milk packs of Company A, Company B, Company C, Company D and Company E was washed and dried, and then the paper pack 2 was prepared.
0 g was placed in a container for paper pack treatment equipped with a backflow cooler and a stirrer, and 1000 g of toluene was added thereto as a solvent.
Was added and heated to 110 ° C. with slow stirring of the solvent. In Example 2, the same processing as in Example 1 was performed except that the solvent was changed to toluene. However, for the secondary treatment, a solution obtained by cooling the solvent after the primary treatment and then removing and recovering the thermoplastic resin by filtration was used. The recovery of the solvent used for the primary treatment by distillation was 98.1%. Table 2 shows the processing results.

<Table 2> Type Recovered paper (g) Recovered resin (g) Total (g) Company A product 16.2 3.8 20.0 Company B product 16.3 3.7 20.0 Company C product 16.7 3.3 20.0 Company D product 16.2 3.8 20.0 Company E product 16.5 3.5 20.0 Total 81.9 18.1 100.0 Solvent recovery (secondary treatment) After) 93.3% The recovered paper according to Example 2 was white, smooth, and retained its shape. Example 3 100 g of a sake pack was prepared as a paper pack container, 1000 g of mixed xylene was used as a solvent, and the same apparatus as in Example 1 was used.
After performing the primary treatment in the same manner as in Example 1, the secondary treatment was further performed in the same manner as in Example 1. The aluminum foil provided on the inner surface of the sake pack was completely peeled off during the primary treatment. The thermoplastic resin provided on both the inner and outer surfaces of the sake pack was completely peeled off by the primary treatment. After the secondary treatment, paper, thermoplastic resin, and aluminum foil could be completely separated and recovered. Of course, the adhesive parts on the bottom and side surfaces of the sake pack were completely peeled off. Table 3 shows the amounts of recovered paper, thermoplastic resin, and aluminum foil based on the results of this treatment.

<Table 3> Paper 69.8 g Thermoplastic resin 8.4 g Aluminum foil 21.7 g Total 99.9 g Solvent recovery rate (after secondary treatment) 95.8% The recovered paper according to Example 3 is white. It was smooth and maintained morphology. [Example 4] The same as Example 1 except that the same milk packs of Company A, Company B, Company C, and Company D as in Example 1 were used except that the thermoplastic resin was separated and collected and 900 g of the solvent collected by filtration and purification was used. Was subjected to a primary treatment and a secondary treatment. Table 4 shows the processing results.

<Table 4> Type Collected paper (g) Collected resin (g) Total (g) Company A product 84.6 15.4 100.0 Company B product 83.0 17.0 100.0 Company C product 80.3 19.7 100.0 D company product 81.6 18.5 100.1 Solvent recovery rate (after secondary treatment) 96.0%

[0025]

The method for separating and recovering food packaging laminate material of the present invention has the following effects because it is configured as described above. (1) Paper / thermoplastic resin or paper / thermoplastic resin / aluminum foil which is a constituent material of the paper pack container can be completely separated and collected. (2) Since no impurities are mixed in the collected materials, each material can be easily reused. (3) The used solvent can be used for recycling. (4) The processing time required for separation and collection is short, and materials can be collected efficiently.

[Brief description of the drawings]

FIG. 1 is a process diagram of a method for separating and recovering a laminated material for food packaging according to an embodiment.

Claims (4)

[Claims] 1. A paper pack container for food packaging, wherein a thermoplastic resin layer is provided on at least the inner surface of the inner and outer surfaces of a paper base material.
Alternatively, an empty container of a food packaging paper pack container further provided with aluminum foil on the inner surface of the thermoplastic resin layer is heated in an aromatic solvent having a specific solubility parameter (solubility parameter). Separating and recovering paper / thermoplastic resin or paper / thermoplastic resin / aluminum foil from water, and recycling and using a solvent. 2. A paper pack container for packaging food, wherein a thermoplastic resin layer is provided on at least the inner surface of both the inner and outer surfaces of a paper substrate.
Alternatively, an empty container of a food packaging paper pack container further provided with an aluminum foil on the inner surface of the thermoplastic resin layer is placed in an aromatic solvent having a solubility parameter (solubility parameter) of 8.5 to 9.3 in an aromatic solvent. Heating in a temperature range from ℃ to the boiling point of the solvent, separating and recovering paper / thermoplastic resin or paper / thermoplastic resin / aluminum foil from the solvent, and recycling the solvent for food packaging. Material separation and collection method. 3. A paper pack container for food packaging, wherein a thermoplastic resin layer is provided on at least the inner surface of both the inner and outer surfaces of a paper substrate.
Alternatively, an empty container of a food packaging paper pack container further provided with an aluminum foil on the inner surface of the thermoplastic resin layer is placed in an aromatic solvent having a solubility parameter (solubility parameter) of 8.5 to 9.3 in an aromatic solvent. Heating in a temperature range from ℃ to the boiling point of the solvent, removing the paper or paper or aluminum foil from the solvent, cooling the solvent containing the thermoplastic resin after removal to 10 ℃ or less, the thermoplastic resin in the solvent Isolate by filtration or distill off the solvent to separate the thermoplastic resin and the solvent and remove the thermoplastic resin, thereby separating and recovering paper, thermoplastic resin or paper, thermoplastic resin, and aluminum foil from the solvent. And a method for separating and recovering a laminated material for food packaging, wherein the solvent is recycled. 4. The paper or paper / aluminum foil removed by the heat treatment, using a solvent from which a thermoplastic resin has been removed,
By repeating the heating / cooling / filtration or distillation process, paper / thermoplastic resin / solvent or paper / thermoplastic resin /
4. The method for separating and recovering a laminated material for food packaging according to claim 3, wherein the aluminum foil and the solvent are isolated and recovered.