KR102766832B1 - Additive for mixture of PET and HDPE, manufacturing method for the same, recycling method for mixture of PET and HDPE using the same - Google Patents

Abstract

The present invention relates to an additive for recycling a PET and HDPE mixture, a method for producing the same, and a method for recycling a PET and HDPE mixture using the same.
A method for producing an additive for recycling a PET and HDPE mixture according to an embodiment of the present invention comprises the steps of mixing high density polyethylene (HDPE), an initiator, and maleic anhydride (MA).

Description

Additive for mixture of PET and HDPE, manufacturing method for the same, recycling method for mixture of PET and HDPE using the same

The present invention relates to an additive for recycling a PET and HDPE mixture, a method for producing the same, and a method for recycling a PET and HDPE mixture using the same.

Plastics have played a major role in the development of industry and the improvement of quality of life, but they are recognized as a major factor in environmental destruction because they are discarded in large quantities and decompose very slowly in nature. To solve this problem, recycling technologies that reuse waste plastics are being developed.

There are various polymer resins in plastic materials such as PET, PE, LDPE, HDPE, and PP, and two or more types of polymer resins are sometimes used in one plastic product. Since the physical and chemical properties of polymer resins differ depending on the type, it is very difficult to recycle different types of plastics at once without separating them. To solve this problem, plastics are separated by component and then recycled, but there is a problem that the recycling cost increases.

The prior art document discloses a recycled wire sleeve made by mixing PET and HDPE in an 8:2 ratio and mixing 5 to 20 wt% of a compatibilizer therein.

Korean Patent Publication No. 10-1621028

The purpose of the present invention is to provide an additive for recycling a PET and HDPE mixture capable of recycling waste plastics made of different polymer resins, a method for producing the additive, and a method for recycling a PET and HDPE mixture using the additive.

Additionally, the present invention can reduce the recycling cost of PET and HDPE.

In addition, a recycled composition of a PET and HDPE mixture having excellent flexural modulus can be manufactured.

A method for producing an additive for recycling a PET and HDPE mixture according to an embodiment of the present invention comprises the steps of mixing high density polyethylene (HDPE), an initiator, and maleic anhydride (MA).

The additive for recycling the above PET and HDPE mixture can be expressed by structural formula 1.

[Structural formula 1]

(where x and y are natural numbers).

The above MA can be expressed by structural formula 2.

[Structural formula 2]

.

The above initiator may be di-(tert-butyl-peroxy-isopropyl)benzene.

The above Di(tert-butyl-peroxy-isopropyl)benzene can be expressed by structural formula 3.

[Structural formula 3]

.

The content of the above MA may be 0.5 to 1.5 phr with respect to the above HDPE.

The content of the above initiator may be 0.05 to 0.15 phr with respect to the HDPE.

The step of mixing the above HDPE, initiator and MA can be performed by heating the mixture to 180 to 220°C.

An additive for recycling of a PET and HDPE blend according to an embodiment of the present invention is maleic anhydride grafted high density polyethylene (MA-g-HDPE).

The above MA-g-HDPE improves compatibility by lowering the interfacial tension between PET and HDPE.

The above MA-g-HDPE is cross-linked between maleic anhydride (MA) and high-density polyethylene (HDPE).

In the above MA-g-HDPE, the grafting yield of MA to HDPE is 0.5 wt% or more.

The content of the above MA may be 0.50 to 0.60 wt% of the total content of the MA-g-HDPE.

A method for recycling a PET and HDPE mixture according to an embodiment of the present invention comprises the steps of: preparing a mixture of polyethylene terephthalate (PET) and high-density polyethylene (HDPE); and adding maleic anhydride grafted high-density polyethylene (MA-g-HDPE) to the mixture.

The content of the above MA-g-HDPE can be 1 to 5 hpr for the PET and HDPE mixture.

The above MA-g-HDPE may be cross-linked between maleic anhydride (MA) and high-density polyethylene (HDPE). The content of the MA may be 0.50 to 0.60 wt% of the total content of the MA-g-HDPE.

In the step of adding the above MA-g-HDPE, the mixture to which the MA-g-HDPE is added can be heated to 230 to 280°C.

An additive for recycling a PET and HDPE mixture according to an embodiment of the present invention, a method for producing the additive, and a method for recycling a PET and HDPE mixture using the additive can recycle waste plastics made of different polymer resins.

Additionally, the present invention can reduce the recycling cost of PET and HDPE.

In addition, a recycled composition of a PET and HDPE mixture having excellent flexural modulus can be manufactured.

Figure 1 is an SEM photograph of Examples 6 and 7 and Comparative Examples 1 and 2.
Figure 2 illustrates the results of measuring the flexural elastic modulus of Examples 5 to 7 and Comparative Examples 1 and 2.
Figure 3 illustrates the tensile strength measurement results of Examples 5 to 7 and Comparative Examples 1 and 2.

Hereinafter, preferred embodiments of the present invention will be described with reference to the attached drawings. However, the embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided to more completely explain the present invention to a person having average knowledge in the pertinent art. It is to be understood that the expression “including” a certain component throughout the specification does not exclude other components, but rather may further include other components, unless specifically stated otherwise.

A method for producing an additive for recycling a PET and HDPE mixture according to an embodiment of the present invention comprises the steps of mixing high density polyethylene (HDPE), an initiator, and maleic anhydride (MA).

The above HDPE is a thermoplastic polymer produced from the monomer ethylene, and is used as a material for lids of plastic containers, etc. The above HDPE may be one generally used in the relevant field and is not particularly limited. In the present invention, compatibility with PET can be increased by grafting HDPE with MA. The above HDPE can be expressed by structural formula 4.

[Structural formula 4]

(where n is a natural number)

The above MA is an anhydride of maleic acid, which may be commonly used in the relevant field and is not particularly limited. The above MA can be expressed by structural formula 2.

[Structural formula 2]

.

The above initiator may be di-(tert-butyl-peroxy-isopropyl)benzene. The above Di(tert-butyl-peroxy-isopropyl)benzene may be represented by structural formula 3.

[Structural formula 3]

.

The content of the above MA may be 0.5 to 1.5 phr with respect to the HDPE. If the content of MA is out of the range, there is a problem that the grafting yield and grafting yield are lowered.

The content of the initiator may be 0.05 to 0.15 phr with respect to the HDPE. If the content of the initiator is out of the range, there is a problem that the grafting yield and grafting yield are lowered.

This step can be performed through a general extruder, and mixing and extrusion can be performed while the mixture is heated to 180 to 220°C. This can increase the grafting rate and grafting efficiency. This step can be performed for 30 minutes to 2 hours.

The additive for recycling the PET and HDPE mixture manufactured through the present manufacturing method is maleic anhydride grafted high density polyethylene (MA-g-HDPE), which can be expressed by structural formula 1.

[Structural formula 1]

(where x and y are natural numbers).

Maleic anhydride (MA) is cross-linked between high-density polyethylene (HDPE), and the MA-g-HDPE improves compatibility by lowering the interfacial tension between PET and HDPE. In the MA-g-HDPE, the grafting yield of MA to HDPE is 0.5 wt% or more, and the grafting efficiency is 50% or more. In addition, the content of the MA may be 0.50 to 0.60 wt% of the total content of the MA-g-HDPE.

A method for recycling a PET and HDPE mixture according to an embodiment of the present invention comprises the steps of: preparing a mixture of polyethylene terephthalate (PET) and high-density polyethylene (HDPE); and adding maleic anhydride grafted high-density polyethylene (MA-g-HDPE) to the mixture.

The above PET is the most common thermoplastic polymer resin among polyester series resins and is widely used in clothing, containers, etc. The above PET may be generally used in the relevant field, and may be waste plastic in particular. The above PET may be expressed by structural formula 5.

[Structural formula 5]

(where n is a natural number)

The above HDPE is a thermoplastic polymer produced from the monomer ethylene, and is used as a material for lids of plastic containers, etc. The above HDPE may be a material commonly used in the relevant field, and may particularly be waste plastic.

The content of the above PET and HDPE may be 7:3 to 9:1 in weight ratio, preferably 7.5:2.5 to 8.5:1.5, and more preferably 8:2. This is because the weight ratio of PET and HDPE in general waste plastics such as beverage containers is as above. An embodiment of the present invention aims to provide an additive provided for mixing waste plastics mixed with general PET and HDPE.

The above MA-g-HDPE is as described above. MA-g-HDPE can function as a compatibilizer that increases the compatibility of PET and HDPE. In the step of adding the MA-g-HDPE, the content of the MA-g-HDPE may be 1 to 5 hpr, preferably 2.5 to 3.5 phr, with respect to the PET and HDPE mixture. If the content of the MA-g-HDPE is low, there are problems in that the tensile strength decreases, the flexural modulus decreases, and the impact strength decreases, and if the content of the MA-g-HDPE is high, there are problems in that the flexural modulus decreases.

In the step of adding the above MA-g-HDPE, the mixture to which the MA-g-HDPE is added can be heated to 230 to 280°C, and this can be performed for 30 minutes to 2 hours. At that temperature, MA-g-HDPE, PET, and HDPE are mixed to produce a mixture in a form that can be recycled.

Next, the manufactured mixture can be cooled and crushed to produce a powder or pellet shape. The recycled plastic manufactured in this way can be manufactured into a desired product by heating and melting.

Manufacturing Example 1; Manufacturing of additive for recycling of PET and HDPE mixtures

Example 1: XP6070 from Daerim Co., Ltd. was prepared as HDPE, M188 from Sigma Aldrich as MA, and PK-14 (Di(tert-butyl-peroxy-isopropyl)benzene) from AkzoNobel as an initiator. 500 g of HDPE, 0.25 g of initiator, and 5 g of MA were mixed.

Example 2: The same procedure as Example 1 was followed, except that 500 g of HDPE, 0.25 g of initiator, and 10 g of MA were mixed.

Example 3: The same procedure as Example 1 was followed, except that 500 g of HDPE, 0.5 g of initiator, and 5 g of MA were mixed.

Example 4: The same procedure as Example 1 was followed, except that 500 g of HDPE, 0.5 g of initiator, and 10 g of MA were mixed.

Calculation of grafting yield and grafting efficiency

The grafting rate refers to the degree to which MA is grafted onto HDPE. The grafting rate can be calculated using the following mathematical formula 1.

[Mathematical Formula 1]

The molecular weight of MA is 98.06, and the molecular weight of KOH is 56.1. The acid value can be calculated using the following mathematical formula 2.

[Mathematical formula 2]

The grafting efficiency refers to the grafted ratio among the injected MA. The grafting efficiency can be calculated using mathematical formula 3.

[Mathematical Formula 3]

In order to calculate the grafting rate and grafting efficiency, Examples 1 to 4 were each dissolved in a xylene solvent, 1.5 ml of 1 M HCl was added, and 1 ml of a 1% phenolphthalein solution was added as a test substance. The volume of KOH used was measured by titrating with 0.05 KOH.

The grafting rates and grafting efficiencies of Examples 1 to 4 are as shown in the table below. According to Table 1, it can be seen that the grafting rate and grafting efficiency of Example 3 are the best.

division Example 1 Example 2 Example 3 Example 4 Grafting rate 0.245 0.270 0.539 0.392 Grafting efficiency (%) 24.5 13.5 53.9 19.6

Manufacturing Example 2: Manufacturing of recycled plastic mixed with PET and HDPE

Example 5: XP6070 of Daerim Co., Ltd. as HDPE, PET-Cool of Lotte Chemical Co., Ltd. as PET, and the additive manufactured in Example 3 were prepared. 200 g of HDPE, 800 g of PET, and 10 g of additive (compatibility agent) were mixed so that the additive became 1 phr with respect to the total polymer material. The mixture was dried at 60°C for 24 hours, placed in a twin-screw extruder, and reacted under conditions of 200 rpm and 255°C. Next, the mixture upon completion of the reaction was dried at 60°C for 24 hours, placed in a hot press, and processed under conditions of 265°C and 100 bar to manufacture a specimen.

Example 6: The same procedure as Example 5 was followed, except that 200 g of HDPE, 800 g of PET, and 30 g of additive were mixed so that the amount of additive was 3 phr relative to the total polymer material.

Example 7: The same procedure as Example 5 was followed, except that 200 g of HDPE, 800 g of PET, and 50 g of additive were mixed so that the amount of additive was 5 phr relative to the total polymer material.

Comparative Example 1: Manufactured using only PET, excluding HDPE and additives. The manufacturing method was the same as in Example 1.

Comparative Example 2: Manufactured using only 200 g of HDPE and 800 g of PET, excluding additives. The manufacturing method was performed in the same manner as in Example 1.

Experimental Example 1: Morphology Analysis through SEM Photography

The surfaces of the specimens of Examples 6 and 7 and Comparative Examples 1 and 2 were observed at a magnification of 3,000 times using JEOL, JSM-6500. Fig. 1 is an SEM photograph of Examples 6 and 7 and Comparative Examples 1 and 2. Referring to Fig. 1, it can be seen that the addition of the additive reduces the interface size and improves usability.

Experimental Example 2: Flexure modulus measurement

The flexural modulus was measured according to ASTM D790 using H5KT (UTM, universal material testing machine) of Tinius Olsen, using Examples 5 to 7 and Comparative Examples 1 and 2 as specimens. The croshead speed was 5 mm/min.

Figure 2 illustrates the results of measuring the flexural modulus of Examples 5 to 7 and Comparative Examples 1 and 2. Referring to Figure 2, Examples 5 to 7 have flexural moduli between those of Comparative Examples 1 and 2, and it can be seen that Example 6 is the best among the Examples.

Experimental Example 3: Tensile strength measurement

The flexural modulus was measured according to ASTM D638 using H5KT (UTM, universal material testing machine) of Tinius Olsen, using Examples 5 to 7 and Comparative Examples 1 and 2 as specimens. The croshead speed was 5 mm/min.

Figure 3 illustrates the tensile strength measurement results of Examples 5 to 7 and Comparative Examples 1 and 2. Referring to Figure 3, it can be seen that Examples 6 and 7 have higher tensile strengths than Comparative Examples 1 and 2.

Referring to Experimental Examples 1 and 2, it can be seen that Example 6 containing 3 phr of MA-g-HDPE as an additive is the best in terms of compatibility, flexural modulus, and tensile strength.

The present invention is not limited to the above-described embodiments and the attached drawings, but is intended to be limited by the appended claims. Accordingly, various substitutions, modifications, and changes may be made by those skilled in the art within the scope that does not depart from the technical spirit of the present invention described in the claims, and this will also fall within the scope of the present invention.

Claims (16)

Comprising a step of mixing high density polyethylene (HDPE), an initiator and maleic anhydride (MA),
The content of the above MA is 0.5 to 1.5 phr with respect to the above HDPE.
Method for producing an additive for recycling PET and HDPE blends. In the first paragraph,
The additive for recycling the above PET and HDPE mixture is represented by structural formula 1.
Method for producing additives for recycling PET and HDPE blends:
[Structural formula 1]

(where x and y are natural numbers).
In the first paragraph,
The above MA is expressed by structural formula 2.
Method for producing additives for recycling PET and HDPE blends:
[Structural formula 2]
.
In the first paragraph,
The above initiator is di-(tert-butyl-peroxy-isopropyl)benzene.
In the first paragraph,
The above Di(tert-butyl-peroxy-isopropyl)benzene is represented by structural formula 3.
Method for producing additives for recycling PET and HDPE blends:
[Structural formula 3]
.
delete In the first paragraph,
The content of the above initiator is 0.05 to 0.15 phr with respect to the HDPE.
Method for producing an additive for recycling PET and HDPE blends.
In the first paragraph,
The step of mixing the above HDPE, initiator and MA is to heat the mixture to 180 to 220°C.
Method for producing an additive for recycling PET and HDPE blends.
It is maleic anhydride grafted high density polyethylene (MA-g-HDPE),
Improve compatibility by lowering the interfacial tension between PET and HDPE,
Manufactured by the method of Article 1,
Additive for recycling of PET and HDPE blends. In Article 9,
The above MA-g-HDPE is a cross-linked polymer in which maleic anhydride (MA) is cross-linked between high-density polyethylene (HDPE).
Additive for recycling of PET and HDPE blends.
In Article 10,
The grafting yield of the above MA and HDPE is 0.5 or more.
Additive for recycling of PET and HDPE blends.
In Article 9,
The content of the above MA is 0.50 to 0.60 wt% of the total content of the MA-g-HDPE.
Additive for recycling of PET and HDPE blends.
A step of preparing a mixture of polyethylene terephthalate (PET) and high density polyethylene (HDPE); and
A step of adding maleic anhydride grafted high density polyethylene (MA-g-HDPE) to the above mixture;
The high-density polyethylene grafted with the above maleic anhydride is that of claim 9.
Method for recycling PET and HDPE blends. delete In Article 13,
The above MA-g-HDPE is cross-linked between maleic anhydride (MA) and high-density polyethylene (HDPE).
The content of the above MA is 0.50 to 0.60 wt% of the total content of the MA-g-HDPE.
Method for recycling PET and HDPE blends.
In Article 13,
In the step of adding the above MA-g-HDPE,
The mixture to which the above MA-g-HDPE is added is heated to 230 to 280°C.
Method for recycling PET and HDPE blends.