JP2021024904A - Method for regenerating polymer compound - Google Patents

Abstract

To provide a method for material-recycle a silane cross-linked polyethylene-containing polyethylene resin by using a simple apparatus and adding a highly safe additive to thermo-plasticize the resin in an effective manner.SOLUTION: A material-recyclable regenerated polymer can be obtained by applying shear stress to a polymer compound in which a cross-linked polyethylene resin and an additive selected from an aliphatic compound having 16 or more carbon atoms and having one or more hydroxyl groups and a boiling point of 300°C or more are mixed, to make it thermo-plasticized.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for regenerating a polymer compound. More specifically, the present invention relates to a method for thermoplasticizing and regenerating a polyethylene resin containing silane cross-linked polyethylene and a polymer compound containing an additive.

Polyethylene waste has been recycled as a raw material for plastics, but the recycled polyethylene is mainly high-density polyethylene or low-density polyethylene, which is non-crosslinked polyethylene. On the other hand, cross-linked polyethylene obtained by cross-linking non-cross-linked polyethylene does not melt even when heat is applied, so that material recycling is extremely difficult. However, in recent years, a material recycling method for cross-linked polyethylene has been studied.

Cross-linked polyethylene is roughly classified into cross-linked polyethylene cross-linked with an organic peroxide and silane-cross-linked polyethylene cross-linked with a silanol condensation catalyst. Peroxide cross-linked polyethylene can be recycled as a material by relatively easily decomposing the cross-linked points by applying shear stress at high temperature using a twin-screw extruder and thermoplasticizing the cross-linked polyethylene.

On the other hand, silane cross-linked polyethylene is obtained by adding a silane coupling agent to non-cross-linked polyethylene, and the cross-linked portion binds silicon and oxygen, which is called a siloxane bond, by a silane graft reaction. This bond has about 1.25 times higher binding energy than the carbon-carbon bond forming the main chain of polyethylene. Therefore, when heat and shear stress are simply applied, the carbon-carbon bond is broken first, and the siloxane bond remains, which makes it difficult to recycle the material by thermoplasticization.

Therefore, various methods of thermoplasticization for reusing silane cross-linked polyethylene have been studied. For example, a recycling method (Patent Document 1) that can continuously recycle a crosslinked polymer under good working efficiency and good thermal efficiency, a molecular weight control is possible, and a relatively simple device is used. (Patent Document 2), a method having excellent energy saving and storage stability when cross-linking a cross-linked portion of a cross-linked polymer (Patent Document 3), and a method of thermoplasticizing a cross-linked polyethylene mixture to have a molecular weight. A method for obtaining a high-quality product with a small decrease in the amount of the polymer (Patent Document 4) is known.

In the method for thermoplasticizing silane cross-linked polyethylene described in Patent Document 1, silane cross-linked polyethylene is supplied to a high-temperature reaction vessel by a liquid feed pump, and a supercritical fluid of alcohol is generated in the reaction vessel. At the same time, the produced supercritical fluid is reacted with silane cross-linked polyethylene to obtain thermoplastic polyethylene.

Further, in the method for thermoplasticizing silane crosslinked polyethylene described in Patent Document 2, the thermoplasticization proceeds by reacting the crosslinked polymer with high temperature alcohol or water while kneading in an extruder.

Further, in the method for thermoplasticizing silane crosslinked polyethylene described in Patent Document 3, a recycled thermoplastic substance formed by cleaving the crosslinked portion of the crosslinked polymer with supercritical alcohol, subcritical alcohol, or high temperature and high pressure alcohol is used. Alcohol is added as an anti-recrosslinking agent to obtain thermoplastic polyethylene with high storage stability.

Then, in the method for thermoplasticizing silane cross-linked polyethylene described in Patent Document 4, a polymer compound and a drug for reacting with the polymer compound are supplied to a reaction extruder, and the polymer compound and the drug are used for reaction. Cross-linked polyethylene is thermoplasticized by shear kneading in the extruder.

Japanese Unexamined Patent Publication No. 2002-249618 Tokuseki 2002-332380 Gazette Japanese Unexamined Patent Publication No. 2003-26854 JP-A-2009-197138

However, the method described in Patent Document 1 requires a liquid feed pump, a separator, and two extruders because it uses a supercritical or subcritical fluid, and the apparatus becomes complicated. In addition, since methanol, ethanol, etc., which have a boiling point lower than the reaction temperature of 320 ° C. and are highly toxic, are used as the additive, there is a risk of flammability or explosiveness at high temperatures, and environmental pollution is likely to occur. Then, it is difficult to control the reaction because the thermoplastic reaction is carried out in a closed container under supercritical or subcritical, that is, at a high temperature and high pressure of 320 ° C. and 12 MPa.

Further, since the method described in Patent Document 2 uses a ram extruder or a uniaxial extruder, sufficient shear stress is not applied, and effective thermoplasticization cannot be performed. In addition, since methanol, ethanol, dodecanol, etc., which have a boiling point lower than the reaction temperature of 320 ° C. and are highly toxic, are used as additives, there is a risk of flammability and explosiveness at high temperatures, and environmental pollution is likely to occur. Then, since the thermoplastic reaction is carried out in a closed container under a high temperature and high pressure of 320 ° C. or higher and 12 MPa or higher, it is difficult to control the reaction.

Further, the production method described in Patent Document 3 is poor in productivity because the reaction is carried out in a batch manner. In addition, since methanol, ethanol, propanol, etc., which have a boiling point lower than the reaction temperature of 320 ° C. and are highly toxic, are used as the additive, there is a risk of flammability or explosiveness at high temperatures, and environmental pollution is likely to occur. Then, it is difficult to control the reaction because the thermoplastic reaction is carried out under supercritical or subcritical, that is, in a closed container having a high temperature and high pressure of 320 ° C. or higher and 12 MPa or higher.

Since the method described in Patent Document 4 uses a supercritical or subcritical fluid, the apparatus such as a trapper, a dry vacuum pump, a condenser, and two extruders becomes complicated. In addition, since methanol, ethanol, etc., which have a boiling point lower than the reaction temperature of 330 ° C. and are highly toxic, are used as additives, there is a risk of flammability and explosiveness at high temperatures, and environmental pollution is likely to occur. Then, it is difficult to control the reaction because the thermoplastic reaction is carried out under supercritical or subcritical, that is, in a closed container having a high temperature and high pressure of 330 ° C. or higher and 7.8 MPa or higher.

As described above, the method of performing thermoplasticization in a closed container under high temperature and high pressure using an additive having a boiling point lower than the reaction temperature of thermoplasticization is complicated in terms of equipment, toxicity and environmental pollution by the additive, and so on. There was a problem of difficulty in reaction control.

The present invention has been made to eliminate the above-mentioned inconveniences, and an object of the present invention is to provide a method for easily, safely and effectively thermoplasticizing a polyethylene resin containing silane crosslinked polyethylene and recycling the material. ..

The method for regenerating a polymer compound according to the present invention is a method for regenerating a polyethylene resin containing at least silane crosslinked polyethylene and a polymer compound containing an additive, wherein the polyethylene resin and the additive are mixed to obtain the polymer compound. The additive includes a mixing step of producing and a thermoplastic step of applying shear stress to the polymer compound to thermoplasticize the polymer compound, and the additive has 16 or more carbon atoms and has one or more hydroxyl groups. It is an aliphatic compound having a boiling point of 300 ° C. or higher, and the amount of the additive is 0.1 to 5 parts by weight with respect to 100 parts by weight of the silane crosslinked polyethylene.

The method for regenerating the polymer compound is characterized in that the polyethylene resin contains non-crosslinked polyethylene, and the amount of the non-crosslinked polyethylene is 1 to 30% of the polyethylene resin.

The method for regenerating the polymer compound includes a kneading step of kneading the non-crosslinked polyethylene after the thermoplastic step, and the amount of the non-crosslinked polyethylene is 50 to 300 weight with respect to 100 parts by weight of the silane crosslinked polyethylene. It is characterized by being a part.

In the method for regenerating the polymer compound, the additives are 1-hexadecanol, cis-9-hexadecene-1-ol, 1-heptadecanol, 1-octadecanol, 16-methylheptadecene-1-. All, 9E-octadecene-1-ol, cis-9-octadecen-1-ol, 9Z, 12Z-octadecadien-1-ol, 9E, 12E-octadecadien-1-ol, 9Z, 12Z, 15Z- Octadecatriene-1-ol, 9E, 12E, 15-E-octadecatorien-1-ol, 12-hydroxy-9-octadecene-1-ol, nonadesyl alcohol, 1-eicosanol, heneicosanol, 1 It is characterized by containing at least one selected from the group consisting of -docosanol, cis-13-dococene-1-ol, and 1-tetracosanol.

The method for regenerating a polymer compound is characterized in that the thermoplasticization time of the polymer compound in the thermoplastic step is in the range of 30 to 600 seconds.

The method for regenerating the polymer compound is characterized in that the gel content of the thermoplastic polymer compound after the thermoplastic step is in the range of 10 to 30%.

The method for regenerating a polymer compound is characterized in that the tensile strength of the polymer compound after the kneading step is 15 MPa or more and the elongation rate is 200% or more.

According to the present invention, it is difficult to cause environmental pollution by using an additive having a boiling point higher than the reaction temperature and having low toxicity. Further, since it is not necessary to pressurize more than a certain level in the thermoplastic reaction, it is easy to control the reaction of the thermoplastic. Then, by including the step of kneading the non-crosslinked polyethylene after the thermoplastic step, the high-physical polymer compound can be easily regenerated with only one twin-screw extruder. From the above, it is possible to easily, safely and effectively recycle the material of the polyethylene resin containing the silane cross-linked polyethylene.

It is the schematic which showed the internal structure of the twin-screw extruder which concerns on embodiment of this invention. It is a process drawing of the method of regenerating the polymer compound which concerns on embodiment of this invention. It is a process diagram of the method of regenerating the polymer compound which concerns on modification 1 of embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Explanation of equipment>
FIG. 1 is a schematic view showing an internal structure of a twin-screw extruder according to an embodiment of the present invention. The twin-screw extruder 10 is provided with a drive unit 14 at an end thereof, a cylindrical cylinder 12 extends from the drive unit 14, and a discharge unit 34 is provided at the tip end portion thereof.

A first transport unit 18, a first kneading unit 20, a second transport unit 26, a second kneading unit 28, and a third transport unit 32 are provided in the cylinder 12 in order from the drive unit 14. The first transport section 18, the first kneading section 20, the second transport section 26, the second kneading section 28, and the third transport section 32 are each composed of a pair of screws. Further, the drive unit 14 is connected to the first transport unit 18, and each screw is connected to an adjacent screw. When the drive unit 14 is driven, the screws of the first transport unit 18, the first kneading unit 20, the second transport unit 26, the second kneading unit 28, and the third transport unit 32 rotate at the same time. Further, a heating means (not shown) such as a jacket or a heater for keeping the inside of the cylinder 12 at a predetermined temperature is provided.

The first transport unit 18 is provided with a mechanism in which a pair of screws rotate in different directions. The first transport unit 18 is connected to the drive unit 14 and the first kneading unit 20, and the first input unit 16 is provided at the upper portion. The polymer compound charged from the first charging section 16 is heated and melted in the first transport section 18 and introduced into the first kneading section 20.

The first kneading portion 20 is composed of a pair of screw structures in which a shearing action occurs. The first kneading section 20 is connected to the first transport section 18 and the second transport section 26, and the first degassing section 22 is provided at the upper portion. The polymer compound introduced from the first transport unit 18 is introduced into the second transport unit 26 after being subjected to shear stress and heat in the first kneading unit 20. Further, the gas generated in the first kneading section 20 is discharged from the first degassing section 22 to the outside.

The second transport unit 26 is provided with a mechanism in which the pair of screws rotate in different directions. The second transport section 26 is connected to the first kneading section 20 and the second kneading section 28, and the second input section 24 is provided above the second transport section 26. The input material charged from the second charging unit 24 is introduced into the second kneading unit 28 together with the polymer compound from the first kneading unit 20.

The second kneading portion 28 is formed of a pair of screw shapes that cause mixing and kneading action, and can uniformly knead the polymer compound. The second kneading section 28 is connected to the second transport section 26 and the third transport section 32, and the polymer compound or the like introduced from the second transport section 26 is sufficiently kneaded in the second kneading section 28. It will later be introduced into the third transport unit 32.

The third transport unit 32 is configured by providing a pair or one screw. The third transport unit 32 is connected to the second kneading unit 28 and the discharge unit 34. Further, a second degassing unit 30 is provided above the third transport unit 32, and has a structure in which the gas generated inside the cylinder 12 is discharged to the outside. The polymer compound introduced from the second kneading section 28 passes through the third transport section 32 and is discharged from the discharge section 34 to the outside.

<Process description>
Next, a method for regenerating the polymer compound according to the embodiment of the present invention will be described with reference to FIG. FIG. 2 is a process diagram of a method for regenerating a polymer compound according to an embodiment of the present invention.

(Preparation process: S1)
After the start, the motor in the drive unit 14 of the twin-screw extruder 10 rotates, and the first transport unit 18, the first kneading unit 20, the second transport unit 26, the second kneading unit 28, and the second kneading unit 28 are connected to the drive unit 14. (3) The transport unit 32 rotates. At the same time, the inside of the cylinder 12 is heated to a predetermined temperature by the heating mechanism, and a predetermined time is maintained until the apparatus becomes sufficiently stable.

Here, the shear rate in the first kneading portion is ^{set in the range of 2000 to 4000 s -1} , and the temperature is set in the range of 250 to 350 ° C. If the shear rate in the first kneading section 20 is 2000 s ^-1 or less, sufficient shear stress cannot be obtained, and if the temperature is 250 ° C. or less, the thermoplastic reaction does not proceed. Further, when the shear rate is 4000 s- ¹ or more, or the temperature is 350 ° C. or more, the twin-screw extruder 10 is excessively loaded, which is not preferable.

(Mixing step: S2)
Next, a polyethylene resin containing silane cross-linked polyethylene and an additive are mixed to produce a polymer compound before the thermoplastic treatment. The polyethylene resin may be only silane cross-linked polyethylene, or one or more types of polyethylene selected from peroxide cross-linked polyethylene, high-density polyethylene, and low-density polyethylene may be combined with silane cross-linked polyethylene.

Here, when only the silane cross-linked polyethylene or only the silane cross-linked polyethylene and the peroxide cross-linked polyethylene are put into the twin-screw extruder 10, the cross-linked polytilene is not thermally melted, so that a large load is applied to the twin-screw extruder 10. At that time, if non-crosslinked high-density polyethylene or low-density polyethylene is added, the non-crosslinked polyethylene melts at a high temperature and acts as a lubricant, which greatly reduces the load on the twin-screw extruder 10. preferable.

The amount of non-crosslinked polyethylene is preferably 1 to 30% of the total polyethylene resin. Further, 2 to 10% is preferable. If the amount of non-crosslinked polyethylene is less than 1%, a large load is applied to the twin screw extruder 10. Further, if it is more than 30%, the efficiency of thermoplasticization of the silane cross-linked polyethylene is lowered, which is not preferable.

Here, the amount of the additive is adjusted to 0.1 to 5 parts by weight with respect to 100 parts by weight of the silane cross-linked polyethylene. If the amount of the additive is 0.1 parts by weight or less, the thermoplastic reaction does not proceed, and if 5 parts by weight or more is added, the efficiency of thermoplasticization decreases.

Further, the additive is selected from an aliphatic compound having 16 or more carbon atoms and having one or more hydroxyl groups and having a boiling point of 300 ° C. or higher under atmospheric pressure. Preferably, an aliphatic compound having 16 or more and 24 or less carbon atoms is preferable, and more preferably, an aliphatic compound having 18 or more and 20 or less carbon atoms is preferable. Further, an aliphatic alcohol having a boiling point of 330 ° C. or higher is more preferable.

When the number of carbon atoms is 15 or less, the boiling point becomes less than 300 ° C., and the boiling point is lower than the thermoplastic reaction temperature, so that the inside of the twin-screw extruder 10 becomes high pressure. On the other hand, an aliphatic compound having 25 or more carbon atoms has poor reactivity with a siloxane bond, and thermoplasticization of silane cross-linked polyethylene is unlikely to occur.

Additives were 1-hexadecanol, cis-9-hexadecene-1-ol, 1-heptadecanol, 1-octadecanol, 16-methylheptadecene-1-ol, 9E-octadecene-1-ol, Sis-9-octadecene-1-ol, 9Z, 12Z-octadecatriene-1-ol, 9E, 12E-octadecatien-1-ol, 9Z, 12Z, 15Z-octadecatrien-1-ol, 9E, 12E, 15-E-octadecatriene-1-ol, 12-hydroxy-9-octadecene-1-ol, nonadesyl alcohol, 1-eicosanol, heneicosanol, 1-docosanol, cis-13-docosen-1 It is preferable that at least one type is selected from the group consisting of -ol and 1-tetracosanol, but other aliphatic compounds can also be selected. Of these, 1-octadecanol and 1-eicosanol are more preferred.

(First input process: S3)
The polymer compound in which the polyethylene resin and the additive are mixed is charged from the first charging section 16, heated and melted while rotating around the biaxial screw in the first transport section 18, and introduced into the first kneading section 20. Ru.

(Thermoplasticization step: S4)
Shear stress and heat are applied to the polymer compound in the first kneading portion 20, the cross-linking points of the silane cross-linked polyethylene are cut, and the polymer compound is thermoplasticized. The gas generated as the thermoplasticization proceeds is discharged to the outside of the cylinder 12 from the first degassing section 22 on the upper side of the first kneading section 20. Due to this degassing, the pressure of the first kneading portion 20 becomes close to the atmospheric pressure.

(Discharge process: S5)
After that, the thermoplastic polymer compound is discharged from the discharge section 34 to the outside of the twin-screw extruder 10 through the second transport section 26, the second kneading section 28, and the third transport section 32.

The thermoplastic polymer compound can be used as it is, but its moldability is poor as it is. Therefore, it can be separately kneaded with non-crosslinked polyethylene or another polymer and used as a polymer compound for processing. Therefore, the conditions of the twin-screw extruder 10 and the amount of additives are adjusted so that the gel fraction of the thermoplastic polymer compound is in the range of 10 to 30%.

If the gel fraction is less than 10%, the tensile strength of the polymer compound for processing is low, and the heat resistance and impact resistance of the processed product are lowered. On the other hand, if the gel fraction exceeds 30%, the workability is remarkably deteriorated and the processed product becomes brittle, which is not preferable.

Next, a modification 1 of the above-described embodiment of the present invention will be described with reference to FIG. FIG. 3 is a process diagram of a method for regenerating a polymer compound according to Modification 1 of the embodiment of the present invention.

(Second input process: S4a)
In the first modification, a second charging step (S4a) and a kneading step (S4b) are added between the steps S1 to S4 and the step S5 of the embodiment of the present invention. That is, after passing through the steps S1 to S4, high-density polyethylene or low-density polyethylene is charged from the second charging section 24 in step S4a, and introduced from the second transport section 26 to the second kneading section 28.

Here, the polyethylene charged from the second charging section 24 includes at least one of non-crosslinked high-density polyethylene and low-density polyethylene. The amount of non-crosslinked polyethylene charged from the second charging section 24 is preferably 50 to 300 parts by weight with respect to 100 parts by weight of the polyethylene resin charged from the first charging section. Further, it is more preferably 50 to 100 parts by weight.

If the amount of non-crosslinked polyethylene charged from the second charging section 24 is less than 50 parts by weight, the effect of improving moldability is low, and defects are likely to occur in the molded product. On the other hand, if it exceeds 300 parts by weight, the marial recycling rate of the silane cross-linked polyethylene decreases.

(Kneading process: S4b)
Then, the thermoplastic polymer compound and the high-density polyethylene or low-density polyethylene charged from the second charging section 24 are mixed and kneaded in the second kneading section 28 to obtain a uniform polymer compound.
(Discharge process: S5)
After that, the polymer compound passes through the third transport section and is discharged from the discharge section 34 to the outside of the twin-screw extruder 10 to obtain a regenerated polymer compound.

The regenerated polymer compound obtained as described above has excellent moldability, has a tensile strength of 15 MPa or more, and an elongation rate of 200% or more, and therefore should be used for molded products requiring high strength. Can be done.

The regenerated polymer compound obtained by the present invention can be used for both press molding and injection molding, and is a molded product having high strength, high heat resistance, and high impact resistance.

Hereinafter, the results of the thermoplastic polymer product will be shown according to Examples and Comparative Examples of the present invention, but these Examples do not limit the present invention.

[Tensile test and elongation test]
Tensile tests and elongation tests were performed on regenerated polymer compounds. An autograph AGS system manufactured by Shimadzu Corporation was used as the tensile test and elongation test equipment. The tensile test was carried out by punching a regenerated polymer compound press-molded into a sheet having a thickness of 1 mm in accordance with JIS K6922-2 into the shape of dumbbell No. 3 and using a tensile tester at a speed of 200 mm / min.

[Gel fraction]
The gel fraction was extracted in boiling hot xylene for 8 hours according to JIS-K 6996. Then, the weight after vacuum drying at 140 ° C. for 3 hours was weighed, and the gel fraction was calculated by the following formula from the ratio with the weight before extraction.
Gel fraction (%) = (weight after extraction (g) / weight before extraction (g)) x 100
The gel fraction of the silane cross-linked polyethylene used was 65 to 70%.

Next, Examples 1 to 10 and Comparative Examples 1 to 8 will be described in detail.

※１：ＸＨ：シラン架橋ポリエチレン、ＸＬ：過酸化物架橋ポリエチレン、ＨＤ:高密度ポリエチレン、ＬＤ：低密度ポリエチレン

* 1: XH: Silane cross-linked polyethylene, XL: Peroxide cross-linked polyethylene, HD: High-density polyethylene, LD: Low-density polyethylene

Examples 1 to 4 will be described below. In Examples 1 to 4, 1-octadecanol is added as an additive to 100 parts by weight of a polyethylene resin containing only silane cross-linked polyethylene or silane cross-linked polyethylene and at least one of peroxide cross-linked polyethylene, high-density polyethylene, and low-density polyethylene. 0.1 part by weight was mixed at the ratio shown in Table 1 to obtain a polymer compound. Then, the polymer compound was thermoplasticized, and the gel fraction of the thermoplastic polymer compound was measured.

(Example 1)
Using the twin-screw extruder 10 of FIG. 1, the temperature of ^{the first kneading section was set to 300 ° C., the shear rate was 3000 s -1} , and the kneading time at the first kneading section was set to 60 s (FIG. 2 S1: preparation step). .. Then, a polymer compound was obtained in which 0.1 part by weight of 1-octadecanol was mixed with 100 parts by weight of silane cross-linked polyethylene as an additive (FIG. 2 S2: first mixing step). The mixture was charged into the twin-screw extruder 10 from the first charging section 16 (FIG. 2 S3: charging step). Then, kneading was carried out in the first kneading section 20 for 60 seconds to produce a polymer compound thermoplasticized by a thermoplastic reaction (FIG. 2 S4: thermoplastic step). Then, the thermoplastic polymer compound was discharged from the discharge section 34 through the second transport section 26, the second kneading section 28, and the third transport section 32 to obtain the thermoplastic polymer compound (). FIG. 2 S5: Discharge process). The gel fraction of the obtained polymer compound was 24%.

(Example 2)
A polymer compound was obtained by mixing 95 parts by weight of silane cross-linked polyethylene, 5 parts by weight of high-density polyethylene, and 0.1 parts by weight of 1-octadecanol as an additive (FIG. 2: S2). Other than that, the same test as in Example 1 was carried out to obtain a thermoplastic polymer compound (FIG. 2: S5). The gel fraction of the obtained polymer compound was 20%.

(Example 3)
A polymer compound was obtained by mixing 95 parts by weight of silane cross-linked polyethylene, 5 parts by weight of low-density polyethylene, and 0.1 parts by weight of 1-octadecanol as an additive (FIG. 2: S2). Other than that, the same test as in Example 1 was carried out to obtain a thermoplastic polymer compound (FIG. 2: S5). The gel fraction of the obtained polymer compound was 18%.

(Example 4)
A polymer compound was obtained by mixing 50 parts by weight of cross-linked silane polyethylene, 50 parts by weight of cross-linked peroxide polyethylene, and 0.1 part by weight of 1-octadecanol as an additive (FIG. 2: S2). Other than that, the same test as in Example 1 was carried out to obtain a thermoplastic polymer compound (FIG. 2: S5). The gel fraction of the obtained polymer compound was 15%.

From the results of Examples 1 to 4, a polymer compound having a gel fraction of 10 to 30% was obtained by mixing 0.1 parts by weight of 1-octadecanol as an additive and performing thermoplasticization.

Examples 5 to 6 will be described below. In Examples 5 to 6, a polymer compound obtained by mixing 100 parts by weight of a polyethylene resin composed of only silane cross-linked polyethylene or silane cross-linked polyethylene and peroxide cross-linked polyethylene with 0.2 parts by weight of 1-eicosanol as an additive. And said. Then, the polymer compound was thermoplasticized, and the gel fraction of the thermoplastic polymer compound was measured.

(Example 5)
A polymer compound was obtained by mixing 100 parts by weight of silane cross-linked polyethylene and 0.2 parts by weight of 1-eicosanol as an additive (FIG. 2: S2). Other than that, the test was carried out in the same manner as in Example 1 to obtain a thermoplastic polymer compound in which silane cross-linked polyethylene was thermoplasticized (FIG. 2: S5). The gel fraction of the obtained thermoplastic polymer compound was 26%.

(Example 6)
A polymer compound was obtained by mixing 50 parts by weight of silane cross-linked polyethylene, 50 parts by weight of peroxide cross-linked polyethylene, and 0.2 parts by weight of 1-eicosanol as an additive (FIG. 2: S2). Other than that, the test was carried out in the same manner as in Example 1 to obtain a thermoplastic polymer compound in which silane cross-linked polyethylene was thermoplasticized (FIG. 2: S5). The gel fraction of the obtained thermoplastic polymer compound was 22%.

From the results of Examples 5 to 6, a polymer compound having a gel fraction of 10 to 30% was obtained by mixing 0.2 parts by weight of 1-eicosanol and performing thermoplasticization.

Examples 7 to 10 will be described below. In Examples 7 to 10, high-density polyethylene or low-density polyethylene was kneaded after thermoplasticization of the polymer compound to produce a regenerated polymer compound, and the gel fraction, tensile strength and elongation were measured.

(Example 7)
A polymer compound was obtained by mixing 100 parts by weight of silane cross-linked polyethylene and 0.5 parts by weight of 1-octadecanol as an additive (FIG. 3: S2). In addition, 100 parts by weight of high-density polyethylene was charged from the second charging unit 24 (FIG. 3: S4a). Then, the thermoplastic polymer compound and the high-density polyethylene were kneaded in the second kneading section 28 (FIG. 3: S4a) to obtain a regenerated polymer compound in which the thermoplastic polymer compound and the high-density polyethylene were mixed (FIG. 3: S4a). FIG. 3: S5). The gel fraction of the obtained polymer compound was 19%. The tensile strength was 29 MPa and the elongation rate was 250%.

(Example 8)
A polymer compound was obtained by mixing 95 parts by weight of silane cross-linked polyethylene, 5 parts by weight of high-density polyethylene, and 0.5 parts by weight of 1-octadecanol as an additive (FIG. 3: S2). Other than that, the test was carried out in the same manner as in Example 7 to obtain a regenerated polymer compound (FIG. 3: S5). The gel fraction of the obtained polymer compound was 15%. The tensile strength was 28 MPa and the elongation rate was 261%.

(Example 9)
95 parts by weight of silane cross-linked polyethylene, 5 parts by weight of low-density polyethylene, and 0.5 parts by weight of 1-octadecanol as an additive were mixed to obtain a polymer compound (FIG. 3: S2). In addition, 100 parts by weight of low-density polyethylene was charged from the second charging unit 24 (FIG. 3: S4a). Other than that, the test was carried out in the same manner as in Example 7 to obtain a regenerated polymer compound (FIG. 3: S5). The gel fraction of the obtained polymer compound was 16%. The tensile strength was 18 MPa and the elongation rate was 280%.

(Example 10)
A polymer compound was obtained by mixing 50 parts by weight of silane cross-linked polyethylene, 50 parts by weight of peroxide cross-linked polyethylene, and 0.5 part by weight of 1-octadecanol as an additive (FIG. 3: S2). Other than that, the test was carried out in the same manner as in Example 9 to obtain a regenerated polymer compound (FIG. 3: S5). The gel fraction of the obtained polymer compound was 18%. The tensile strength was 17 MPa and the elongation rate was 320%.

As shown in Examples 7 to 10, the regenerated polymer compound has a tensile strength of 17 or more and an elongation rate of 250% or more, and can be used as polyethylene for regeneration.

Comparative Examples 1 to 4 will be described below. In Comparative Examples 1 to 4, 100 parts by weight of a polyethylene resin containing only silane cross-linked polyethylene or silane cross-linked polyethylene and at least one of peroxide cross-linked polyethylene, high-density polyethylene, and low-density polyethylene was used, and no additive was added. Thermoplasticization was performed using only polyethylene resin, and the gel fraction of the thermoplasticized polymer compound was measured. The conditions for thermoplasticization are the same as in Examples 1 to 4.

(Comparative Example 1)
Thermoplasticization was performed using only 100 parts by weight of silane cross-linked polyethylene (FIG. 2: S4). Other than that, the test was carried out in the same manner as in Example 1 to obtain a polymer compound in which silane cross-linked polyethylene was thermoplasticized (FIG. 2: S5). The gel fraction of the obtained thermoplastic polymer compound was 65%.

(Comparative Example 2)
95 parts by weight of silane cross-linked polyethylene and 5 parts by weight of high-density polyethylene were mixed to obtain a polyethylene resin (FIG. 2: S2). Other than that, the same test as in Example 1 was carried out to obtain a thermoplastic polymer compound (FIG. 2: S5). The gel fraction of the obtained polymer compound was 62%.

(Comparative Example 3)
95 parts by weight of silane cross-linked polyethylene and 5 parts by weight of low density polyethylene were mixed to obtain a polyethylene resin (FIG. 2: S2). Other than that, the same test as in Example 1 was carried out to obtain a thermoplastic polymer compound (FIG. 2: S5). The gel fraction of the obtained polymer compound was 58%.

(Comparative Example 4)
50 parts by weight of silane cross-linked polyethylene and 50 parts by weight of peroxide cross-linked polyethylene were mixed to obtain a polyethylene resin (FIG. 2: S2). Other than that, the same test as in Example 1 was carried out to obtain a thermoplastic polymer compound (FIG. 2: S5). The gel fraction of the obtained polymer compound was 55%.

As shown in Comparative Examples 1 to 4, when thermoplasticization is performed only with polyethylene resin without using additives, the gel fraction is 50% or more, which is not suitable for recycling.

Comparative Examples 5 to 8 will be described below. In Comparative Examples 5 to 8, only the polyethylene resin was thermally plasticized under the same conditions as in Comparative Examples 1 to 4, and then high-density polyethylene or low-density polyethylene was kneaded to produce a polymer compound, and the gel fraction, tensile strength and tensile strength were obtained. The elongation rate was measured.

(Comparative Example 5)
100 parts by weight of silane cross-linked polyethylene was used as a polyethylene resin for thermoplasticization (FIG. 3: S4). Other than that, the test was carried out in the same manner as in Example 7 to obtain a polymer compound (FIG. 3: S5). The gel fraction of the obtained polymer compound was 40%. The tensile strength was 6 MPa and the elongation rate was 20%.

(Comparative Example 6)
95 parts by weight of silane cross-linked polyethylene and 5 parts by weight of high-density polyethylene were mixed to obtain a polyethylene resin (FIG. 3: S2). Other than that, the test was carried out in the same manner as in Example 7 to obtain a polymer compound (FIG. 3: S5). The gel fraction of the obtained polymer compound was 42%. The tensile strength was 8 MPa and the elongation rate was 15%.

(Comparative Example 7)
95 parts by weight of silane cross-linked polyethylene and 5 parts by weight of low density polyethylene were mixed to obtain a polyethylene resin (FIG. 3: S2). Other than that, the test was carried out in the same manner as in Example 9 to obtain a polymer compound (FIG. 3: S5). The gel fraction of the obtained polymer compound was 39%. The tensile strength was 7 MPa and the elongation rate was 22%.

(Comparative Example 8)
50 parts by weight of silane cross-linked polyethylene and 50 parts by weight of peroxide cross-linked polyethylene were mixed to obtain a polyethylene resin (FIG. 3: S2). Other than that, the test was carried out in the same manner as in Example 10 to obtain a polymer compound (FIG. 3: S5). The gel fraction of the obtained polymer compound was 40%. The tensile strength was 9 MPa and the elongation rate was 18%.

From the above results, even if a polymer compound is obtained by performing thermoplasticization only with polyethylene resin and then adding non-crosslinked polyethylene, the tensile strength is 10 MPa or less and the elongation rate is 30% or less, which is not suitable for molding. On the other hand, a polymer compound containing silane cross-linked polyethylene was thermally plasticized using an additive, and the obtained recycled polymer compound showed a tensile strength of 15 MPa or more and an elongation rate of 200% or more, and could be sufficiently recycled. there were.

According to the present invention, by using an aliphatic compound having a boiling point higher than the reaction temperature for thermoplasticization as an additive, a polymer compound containing silane cross-linked polyethylene can be easily, safely and effectively thermoplasticized. be able to. The obtained regenerated polymer compound has high moldability and physical property values, and can be used in the material recycling field.

10 Twin-screw extruder 12 Cylinder 14 Drive unit 16 First input unit 18 First transport unit 20 First kneading unit 22 First degassing unit 24 Second input unit 26 Second transport unit 28 Second kneading unit 30 Second desorption Air part 32 Third transport part 34 Discharge part

The method for regenerating a polymer compound according to the present invention is a method for regenerating a polymer compound containing at least a polyethylene resin containing silane crosslinked polyethylene and an additive, wherein the silane crosslinked polyethylene resin and 1 to 30% of the polyethylene resin. A mixing step of mixing the non-crosslinked polyethylene and the additive to produce the polymer compound, a thermoplastic step of applying shear stress to the polymer compound to thermoplasticize the polymer compound, and thermoplasticization. The polymer compound comprises a kneading step of kneading 50 to 300 parts by weight of non-crosslinked polyethylene with respect to 100 parts by weight of the polyethylene resin, and the additive has 16 or more carbon atoms and has 16 or more carbon atoms. It is an aliphatic compound having one or more hydroxyl groups and having a boiling point of 300 ° C. or higher, and the amount of the additive is 0.1 to 5 parts by weight with respect to 100 parts by weight of the silane crosslinked polyethylene.

The method of reproducing a polymer compound according to the present invention, a polyethylene resin containing at least silane crosslinked polyethylene, in the reproducing method of the polymer compound containing the additive, polyethylene and, in the non-crosslinked crosslinked containing the silane crosslinking polyethylene emissions A mixing step of mixing polyethylene and the additive to produce a polymer compound, a thermoplastic step of applying shear stress to the polymer compound to make it thermoplastic, and the thermoplastic polymer compound. Including a kneading step of kneading 50 to 300 parts by weight of non-crosslinked polyethylene with respect to 100 parts by weight of the polyethylene resin, the amount of the non-bridged polyethylene is 1 to 30% of the polyethylene resin. The additive is an aliphatic compound having 16 or more carbon atoms and having one or more hydroxyl groups and having a boiling point of 300 ° C. or higher, and the amount of the additive is 0 with respect to 100 parts by weight of the silane crosslinked polyethylene. It is characterized by having 1 to 5 parts by weight.

The method for regenerating a polymer compound, the additive, 1-hexadecanol, cis-9-hexadecene-1-ol, 1-heptadecanol, 1-octadecanol, 16-methyl-hept-decene-1 All, 9E-octadecene-1-ol, cis-9-octadecen-1-ol, 9Z, 12Z-octadecadien-1-ol, 9E, 12E-octadecadien-1-ol, 9Z, 12Z, 15Z- Octadecatriene-1-ol, 9E, 12E, 15-E-octadecatorien-1-ol, 12-hydroxy-9-octadecene-1-ol, nonadesyl alcohol, 1-eicosanol, heneicosanol, 1 It is characterized by containing at least one selected from the group consisting of -docosanol, cis-13-dococene-1-ol, and 1-tetracosanol.

From the above results, even if a polymer compound is obtained by performing thermoplasticization only with polyethylene resin and then adding non-crosslinked polyethylene, the tensile strength is 10 MPa or less and the elongation rate is 30% or less, which is not suitable for molding. Meanwhile, heat plasticizing a polymer compound containing a silane cross-linked polyethylene with additives, the tensile strength of the obtained reproduction polymer compound or 15 MPa, elongation showed over 200% can be sufficiently recycled there were.

Claims (7)

In a method for regenerating a polymer compound containing at least a polyethylene resin containing silane cross-linked polyethylene and an additive,
A mixing step of mixing the polyethylene resin and the additive to produce the polymer compound, and
It includes a thermoplastic step of applying shear stress to the polymer compound to make it thermoplastic.
The additive is an aliphatic compound having 16 or more carbon atoms and having one or more hydroxyl groups and a boiling point of 300 ° C. or higher.
A method for regenerating a polymer compound, wherein the amount of the additive is 0.1 to 5 parts by weight with respect to 100 parts by weight of the silane crosslinked polyethylene. In the method for regenerating a polymer compound according to claim 1,
The polyethylene resin contains non-crosslinked polyethylene and contains
A method for regenerating a polymer compound, wherein the amount of the non-crosslinked polyethylene is 1 to 30% of the polyethylene resin. In the method for regenerating a polymer compound according to claim 2,
A kneading step of kneading the non-crosslinked polyethylene after the thermoplastic step is included.
A method for regenerating a polymer compound, wherein the amount of the non-crosslinked polyethylene is 50 to 300 parts by weight with respect to 100 parts by weight of the polyethylene resin. In the method for regenerating a polymer compound according to any one of claims 1 to 3,
The additives are 1-hexadecanol, cis-9-hexadecene-1-ol, 1-heptadecanol, 1-octadecanol, 16-methylheptadecene-1-ol, 9E-octadecene-1-ol. , Sis-9-octadecene-1-ol, 9Z, 12Z-octadecadiene-1-ol, 9E, 12E-octadecadiene-1-ol, 9Z, 12Z, 15Z-octadecatriene-1-ol, 9E , 12E, 15-E-octadecatorien-1-ol, 12-hydroxy-9-octadecene-1-ol, nonadesyl alcohol, 1-eicosanol, heneicosanol, 1-docosanol, cis-13-dococene- A method for regenerating a polymer compound, which comprises at least one selected from the group consisting of 1-ol and 1-tetracosanol. In the method for regenerating a polymer compound according to any one of claims 1 to 4,
A method for regenerating a polymer compound, characterized in that the thermoplasticization time of the polymer compound in the thermoplastic step is in the range of 30 to 600 seconds. In the method for regenerating a polymer compound according to any one of claims 1 to 5,
A method for regenerating a polymer compound, wherein the gel fraction of the thermoplastic polymer compound after the thermoplastic step is in the range of 10 to 30%. In the method for regenerating a polymer compound according to any one of claims 1 to 6,
A method for regenerating a polymer compound, characterized in that the tensile strength of the polymer compound after the kneading step is 15 MPa or more and the elongation rate is 200% or more.

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