Decrosslinked polyolefin resin, composition containing same and method for preparing same

Abstract

The present invention provides a decrosslinked polyolefin resin having a maximum strain hardening factor of 5 or less, a degree of crosslinking of 10% or lower, and an elongation of 150% or higher. The present invention can exhibit a low degree of crosslinking, uniform molecular weight distribution and excellent elongation.

Description

Decrosslinked polyolefin resin, composition containing same, and method for producing same

[0001] The present invention relates to a decrosslinked polyolefin resin, a composition comprising the same, and a method for producing the same. More specifically, the present invention relates to a decrosslinked polyolefin resin obtained by recycling a crosslinked polyolefin resin, wherein the decrosslinked polyolefin resin has a maximum value of a strain hardening coefficient (χ) of 5 or less, a degree of crosslinking of 10% or less, and an elongation of 150% or more, a composition comprising the same, and a method for producing the same.

[0002] Cross-linked polyolefin resins possess excellent insulating properties and thermal and chemical resistance, making them suitable for applications such as power cables. Recently, various plastic recycling methods have been studied for resource recycling purposes. However, most cross-linked polyolefin resins are currently not effectively recycled. To address this issue, a method is needed to remove the cross-linked structure of polyolefin resins, thereby decross-linking them.

[0003] Conventional decrosslinked polyolefin resins undergo decrosslinking at high extruder temperatures to maintain a low degree of crosslinking. This process results in an unstable decrosslinking reaction, and the random breakage of the main and branch chains of the crosslinked polyolefin resin leads to a decline in mechanical properties, such as elongation.

[0004] To improve the recycling efficiency of cross-linked polyolefin resins, a uniform decross-linking reaction is required. Furthermore, the development of decross-linked polyolefin resins with a low degree of cross-linking, uniform molecular weight distribution, and excellent elongation, compositions containing such resins, and methods for their manufacture are also needed.

[0005]

[0006] Related prior art includes Republic of Korea Patent Publication No. 10-2022-0121397.

[0007] The purpose of the present invention is to provide a decrosslinked polyolefin resin having a maximum strain hardening coefficient of 5 or less, a low degree of crosslinking, and a high elongation, a composition including the same, and a method for producing the same.

[0008] Another object of the present invention is to provide a decrosslinked polyolefin resin having a uniform molecular weight distribution, a composition including the same, and a method for producing the same by precisely controlling the decrosslinking reaction using a subcritical fluid or a supercritical fluid.

[0009] Another object of the present invention is to provide a method for producing a decrosslinked polyolefin capable of controlling the strain hardening coefficient by changing the injection amount of a supercritical fluid.

[0010] The above and other objects of the present invention can all be achieved by the present invention described below.

[0011] 1. One aspect of the present invention relates to a decrosslinked polyolefin resin. The decrosslinked polyolefin resin is characterized by a maximum value of a strain hardening factor (χ) defined by the following Equation 1 of about 5 or less, a degree of crosslinking of about 10% or less, and an elongation of about 150% or more:

[0012] [Formula 1]

[0013] Strain hardening coefficient (χ) = V'' / (3 * V')

[0014] (In Equation 1, V'' is the extensional viscosity of the decrosslinked polyolefin resin measured at 150°C and a strain rate of 0.1 rad / s, and V' is the shear viscosity of the decrosslinked polyolefin resin measured at 150°C and a shear rate of 0.001 rad / s).

[0015] 2. In the above 1 specific example, the decrosslinked polyolefin resin may be characterized by having a decrosslinking index (DI) of about 50 or more, as defined by the following formula 2:

[0016] [Formula 2]

[0017] DI = E / (C * strain hardening coefficient (χ))

[0018] (In Equation 2, E is the elongation (%), the strain hardening coefficient (χ) is the value calculated in Equation 1, and C is the degree of cross-linking (%)).

[0019] 3. In the above 1 to 2 specific examples, the de-crosslinked polyolefin resin may be characterized by having a weight average molecular weight (Mw) of about 50,000 or more.

[0020] 4. In the above 1 to 3 specific examples, the decrosslinked polyolefin resin may be a decrosslinked product of a peroxide-based crosslinked polyolefin resin, an electron beam-based crosslinked polyolefin resin, or a silane-based crosslinked polyolefin resin.

[0021] 5. In the above specific examples 1 to 4, the decrosslinked polyolefin resin may satisfy the following formula 3:

[0022] [Formula 3]

[0023] 10 ≤ V0' / V' ≤ 700

[0024] (In Equation 3, V0' is the shear viscosity of the crosslinked polyolefin resin measured at a shear rate of 0.001 rad / s, and V' is the shear viscosity of the decrosslinked polyolefin resin measured at a shear rate of 0.001 rad / s).

[0025] 6. In the above 1 to 5 specific examples, the decrosslinked polyolefin resin may be twin-screw extruded in the presence of a subcritical fluid or a supercritical fluid.

[0026] 7. Another aspect of the present invention relates to a composition. The composition comprises the above-described decrosslinked polyolefin resin.

[0027] 8. In the above 7 specific examples, the composition may further include a crosslinked polyolefin resin.

[0028] 9. Another aspect of the present invention relates to a method for producing a decrosslinked polyolefin resin. The method comprises a step of twin-screw extruding a crosslinked polyolefin resin in the presence of a subcritical fluid or a supercritical fluid such that the maximum value of the strain hardening factor (χ) defined by the following equation 1 is about 5 or less, and the decrosslinking index (DI) defined by the following equation 2 is about 50 or more:

[0029] [Formula 1]

[0030] Strain hardening coefficient (χ) = V'' / (3 * V')

[0031] (In Equation 1, V'' is the extensional viscosity of the decrosslinked polyolefin resin measured at a strain rate of 0.1 rad / s at 150°C, and V' is the shear viscosity of the decrosslinked polyolefin resin measured at a shear rate of 0.001 rad / s at 150°C.)

[0032] [Formula 2]

[0033] DI = E / (C * strain hardening coefficient (χ))

[0034] (In Equation 2, E is the elongation (%), the strain hardening coefficient (χ) is the value calculated in Equation 1, and C is the degree of cross-linking (%)).

[0035] 10. In the above 9 specific examples, the de-crosslinked polyolefin resin may be characterized by a crosslinking degree of about 10% or less and an elongation of 150% or more.

[0036] 11. In the above 9 to 10 specific examples, the de-crosslinked polyolefin resin may be characterized by having a weight average molecular weight (Mw) of about 50,000 or more.

[0037] 12. In the above 9 to 11 specific examples, the crosslinked polyolefin resin may include a crosslinked polyolefin resin by peroxide, a crosslinked polyolefin resin by electron beam, or a silane crosslinked polyolefin resin.

[0038] 13. In the above 9 to 12 specific examples, the twin-screw extrusion can be performed at a temperature of about 230°C or higher and 350°C or lower.

[0039] 14. In the above 9 to 13 specific examples, the decrosslinked polyolefin resin can satisfy the following formula 3:

[0040] [Formula 3]

[0041] 10 ≤ V0' / V' ≤ 700

[0042] (In Equation 3, V0' is the shear viscosity of the crosslinked polyolefin resin measured at a shear rate of 0.001 rad / s, and V' is the shear viscosity of the decrosslinked polyolefin resin measured at a shear rate of 0.001 rad / s).

[0043] The present invention has the effect of providing a decrosslinked polyolefin resin having a maximum strain hardening coefficient of about 5 or less, a low degree of crosslinking, a high elongation, and a uniform molecular weight distribution, a composition including the same, and a method for producing the same.

[0044] Figure 1 compares the strain hardening factor over time between the examples and comparative examples.

[0045] Hereinafter, the present invention will be described in more detail. In the present specification, where the terms "includes," "has," and "consists of," are used, other parts may be added, unless "only" is used. When a component is expressed in the singular, it also includes the plural, unless otherwise explicitly stated.

[0046] When interpreting a component, it is interpreted as including the error range even if there is no separate explicit description.

[0047] Hereinafter, a decrosslinked polyolefin resin and a method for producing the same according to an embodiment of the present invention will be specifically described with reference to the drawings.

[0048]

[0049] The present invention relates to a decrosslinked polyolefin resin, a composition comprising the same, and a method for producing the same.

[0050] In general, crosslinking refers to a bond that connects one polymer chain, which is a polymer in which units are repeated and connected, to another polymer chain, and de-crosslinking refers to the process of removing or weakening the crosslinking bond.

[0051] The decrosslinked polyolefin resin according to the present invention can be produced by a decrosslinking reaction of a crosslinked polyolefin resin. The decrosslinking reaction can be performed to control the physical properties of the polymer or to improve recyclability.

[0052] The decrosslinked polyolefin resin of the present invention is characterized in that the maximum value of the strain hardening factor (χ) defined by the following equation 1 is about 5 or less:

[0053] [Formula 1]

[0054] Strain hardening coefficient (χ) = V'' / (3 * V')

[0055] (In Equation 1, V'' is the extensional viscosity of the decrosslinked polyolefin resin measured at a strain rate of 0.1 rad / s, and V' is the shear viscosity of the decrosslinked polyolefin resin measured at a shear rate of 0.001 rad / s).

[0056] When the maximum value of the strain hardening factor (χ) of the decrosslinked polyolefin resin is about 5 or less, there is no increase in the degree of strain hardening due to non-uniform branch chains, and a uniform molecular structure can be maintained after the decrosslinking reaction. In addition, it has excellent mechanical properties, such as a high elongation of about 600% or more, and excellent decrosslinking properties. In a specific example, the strain hardening factor of the decrosslinked polyolefin resin may be about 5 or less, for example, about 1 to 4.5, and in a specific example, about 1 to 4.

[0057] The above-described crosslinked polyolefin resin has a crosslinking degree of 10% or less. In specific examples, the crosslinking degree may be about 5% or less, preferably about 3% or less, more preferably about 1% or less, and most preferably about 0.001 to 0.5%.

[0058] In addition, the above-described decrosslinked polyolefin resin has an elongation of about 150% or more. In specific examples, the elongation may be about 250% or more, for example, about 300% or more, and preferably about 500% to 1300%.

[0059] The above-mentioned decrosslinked polyolefin resin may have a decrosslinking index (DI) of about 50 or more, as defined by the following equation 2:

[0060] [Formula 2]

[0061] DI = E / (C * strain hardening coefficient (χ))

[0062] (In Equation 2, E is the elongation (%), the strain hardening coefficient (χ) is the value calculated in Equation 1, and C is the degree of cross-linking (%)).

[0063] In a specific example, the decrosslinking polyolefin resin may have a decrosslinking index (DI) of about 50 to 5000, for example, about 50 to 3000, preferably about 50 to 500. In this range, not only the decrosslinking property but also the mechanical properties are excellent.

[0064] The above-mentioned cross-linked polyolefin resin may have a weight average molecular weight (Mw) of about 50,000 or more, preferably about 80,000 to 300,000. It has excellent mechanical properties within the above range.

[0065] The above-described decrosslinked polyolefin resin may be a decrosslinked product of a crosslinked polyolefin resin by peroxide, a crosslinked polyolefin resin by electron beam, or a crosslinked polyolefin resin by silane, and preferably a decrosslinked product of a crosslinked polyolefin resin by peroxide. However, it is not limited to the crosslinked polyolefin resin as described above. The polyolefin resin may include an olefin homopolymer such as polyethylene or polypropylene, or an olefin random or block copolymer made of a polymer of two or more olefin monomers. The polyethylene may be ultra-low density polyethylene (ULDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), or a combination thereof. However, it is not limited to the types of polyethylene as described above.

[0066] In a specific example, the above-described decrosslinked polyolefin resin can satisfy the following equation 3:

[0067] [Formula 3]

[0068] 10 ≤ V0' / V' ≤ 700

[0069] (In Equation 3, V0' is the shear viscosity of the crosslinked polyolefin resin measured at a shear rate of 0.001 rad / s, and V' is the shear viscosity of the decrosslinked polyolefin resin measured at a shear rate of 0.001 rad / s).

[0070] The above V0' / V' may be, for example, about 20 to 600, in specific examples about 30 to 500, and preferably about 40 to 300. Excellent decrosslinking properties are achieved within the above range.

[0071]

[0072] Another aspect of the present invention relates to a method for producing a decrosslinked polyolefin resin. The method comprises a step of twin-screw extruding a crosslinked polyolefin resin in the presence of a subcritical fluid or a supercritical fluid such that the maximum value of the strain hardening factor (χ) defined by the following equation 1 is about 5 or less, and the decrosslinking index (DI) defined by the following equation 2 is about 50 or more:

[0073] [Formula 1]

[0074] Strain hardening coefficient (χ) = V'' / (3 * V')

[0075] (In Equation 1, V'' is the extensional viscosity of the decrosslinked polyolefin resin measured at a strain rate of 0.1 rad / s at 150°C, and V' is the shear viscosity of the decrosslinked polyolefin resin measured at a shear rate of 0.001 rad / s at 150°C.)

[0076] [Formula 2]

[0077] DI = E / (C * strain hardening coefficient (χ))

[0078] (In Equation 2, E is the elongation (%), the strain hardening coefficient (χ) is the value calculated in Equation 1, and C is the degree of cross-linking (%)).

[0079] In a specific example, the cross-linked polyolefin resin may include a cross-linked polyolefin resin by peroxide, a cross-linked polyolefin resin by electron beam, or a cross-linked polyolefin resin by silane, and preferably may be a cross-linked polyolefin resin by peroxide. However, it is not limited to the cross-linked polyolefin resin as described above. For example, the polyolefin resin may include an olefin homopolymer such as polyethylene or polypropylene, or an olefin random or block copolymer made of a polymer of two or more olefin monomers. The polyethylene may be ultra-low density polyethylene (ULDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), or a combination thereof. However, it is not limited to the types of polyethylene as described above.

[0080] The above-described crosslinked polyolefin resin may have a crosslinking degree of about 10% or less. In specific examples, the crosslinking degree may be about 5% or less, preferably about 3% or less, more preferably about 1% or less, and most preferably about 0.001 to 0.5%.

[0081] The above-described decrosslinked polyolefin resin may have an elongation of about 150% or more. In specific examples, the elongation may be about 250% or more, for example, about 300% or more, and preferably about 500% to 1300%.

[0082] The above-mentioned cross-linked polyolefin resin may have a weight average molecular weight (Mw) of about 50,000 or more, preferably about 80,000 to 300,000. It has excellent mechanical properties within the above range.

[0083] The above-described decrosslinked polyolefin resin may be characterized by being twin-screw extruded in the presence of a subcritical fluid or a supercritical fluid. The supercritical fluid exists above a certain pressure and temperature, and has both the characteristics of a gas with low viscosity and high diffusivity and the characteristics of a liquid with excellent solubility, resulting in excellent solute penetration and reactivity. In particular, when the supercritical fluid is used, it can penetrate the interior of a polymer resin with a large free volume and uniformly transfer thermal energy. This can solve the problem of uneven thermal energy transfer that occurs during a typical pyrolysis extrusion process. In addition, it is possible to produce a recycled resin of uniform quality during the decrosslinking process of a crosslinked product.

[0084] The above-mentioned twin-screw extrusion may be decrosslinked extruded at a temperature of about 230°C or more and 350°C or less, preferably about 250°C or more and 330°C or less. In the above temperature range, the reduction in molecular weight can be minimized, excellent mechanical properties can be secured, and a low degree of crosslinking can be achieved.

[0085] The above strain hardening coefficient can be controlled by varying the amount of subcritical or supercritical fluid injected into the twin-screw extruder. Conventional decrosslinking reactions of crosslinked polyolefins have the problem of randomly breaking the connections between the main and branch chains, resulting in a decrease in mechanical properties. To address this, the present invention adjusts the strain hardening coefficient by varying the amount of supercritical fluid injected, thereby allowing for a uniform decrosslinking reaction and improving recycling efficiency.

[0086]

[0087] Another aspect of the present invention relates to a composition comprising the above-described decrosslinked polyolefin resin. In a specific example, the composition may comprise a decrosslinked polyolefin resin and a crosslinked polyolefin resin. When the decrosslinked polyolefin and the crosslinked polyolefin are mixed and applied in this way, the mechanical properties (tensile strength and elongation) that may be low when only the decrosslinked polyolefin resin is used can be improved, and additionally, the resin color and odor, etc. can be diluted. In a specific example, the composition may be applied by mixing the crosslinked polyolefin in an amount of about 0.01 to 80 parts by weight with respect to about 100 parts by weight of the decrosslinked polyolefin.

[0088]

[0089] Hereinafter, the present invention will be described in more detail through examples and comparative examples; however, these examples are for the purpose of explanation only and should not be construed as limiting the present invention.

[0090]

[0091] Example

[0092] The product specifications used in the following examples and comparative examples are as follows:

[0093] (a1) Cross-linked polyethylene resin: A polyolefin resin cross-linked by peroxide was used.

[0094] (a2) Cross-linked polyethylene resin: Silane cross-linked polyolefin resin was used.

[0095] (b1) Ethanol: 7.5 wt% to 10.5 wt% was used in a subcritical fluid state under a pressure of 50 bar to 70 bar.

[0096] (b2) Ethanol: 4.5 wt% to 7 wt% was used in a subcritical fluid state under a pressure of 40 bar to 60 bar.

[0097] (b3) Ethanol: 1.5 wt% to 4 wt% was used in a subcritical fluid state under a pressure of 20 bar to 40 bar.

[0098] (b4) Ethanol: 0.1 wt% to 1.5 wt% was used in a subcritical fluid state under a pressure of 10 bar to 30 bar.

[0099]

[0100] Example 1

[0101] Cross-linked polyethylene resin (a1) was extruded using a twin-screw extruder (SM Platek, 30mmф Screw) at a die temperature of 270℃ and 330℃ using ethanol (b1) as a reaction solvent to produce a cross-linked polyethylene resin.

[0102]

[0103] Example 2

[0104] The same procedure as Example 1 was followed, except that ethanol (b2) was used as the reaction solvent.

[0105]

[0106] Example 3

[0107] The same procedure as Example 1 was followed, except that ethanol (b3) was used as a reaction solvent and a twin-screw extruder was used at 300°C and a die temperature of 270°C.

[0108]

[0109] Comparative Example 1

[0110] The same procedure as in Example 1 was followed, except that crosslinked polyethylene resin (a2) was decrosslinked and extruded using a twin-screw extruder at 330°C and a die temperature of 270°C without a reaction solvent.

[0111]

[0112] Comparative Example 2

[0113] The same procedure as in Example 1 was followed, except that crosslinked polyethylene resin (a1) was decrosslinked and extruded using a twin-screw extruder at 330°C and a die temperature of 250°C without a reaction solvent.

[0114]

[0115] Comparative Example 3

[0116] The same procedure as in Example 1 was followed, except that the cross-linked polyethylene resin (a2) was decrosslinked and extruded using a single-screw extruder without a reaction solvent.

[0117]

[0118] Comparative Example 4

[0119] The same procedure as in Example 1 was followed, except that crosslinked polyethylene resin (a1) was decrosslinked and extruded using a twin-screw extruder at 330°C and a die temperature of 270°C without a reaction solvent.

[0120]

[0121] Comparative Example 5

[0122] The same procedure as in Example 1 was followed, except that cross-linked polyethylene resin (a2) was decrosslinked and extruded using a twin-screw extruder at 300°C and a die temperature of 250°C using ethanol (b4) as a reaction solvent.

[0123]

[0124] Comparative Example 6

[0125] The same procedure as in Example 1 was followed, except that crosslinked polyethylene resin (a1) was decrosslinked and extruded using a twin-screw extruder at 300°C and a die temperature of 250°C without a reaction solvent.

[0126]

[0127] The properties of the decrosslinked polyolefin resin were evaluated using the following method, and the results are shown in Table 1:

[0128]

[0129] (1) Cross-linking degree (%)

[0130] The degree of crosslinking was analyzed using xylene according to ASTM D2765. 120-mesh stainless steel was used, and after extracting xylene at a temperature of 150°C or higher, the remaining xylene was removed by drying for 20 hours. The mass of xylene within the mesh before and after extraction was measured, and the percentage of the mass of the insoluble matter relative to the mass of the original material was defined as the degree of crosslinking.

[0131]

[0132] (2) Strain hardening factor (χ)

[0133] The extensional viscosity (V'') of the sample was measured at 150°C and a strain rate of 0.1 rad / s using a rheological measuring device (Modular Compact Rheometer (MCR 702, Anton Paar)). Then, the shear viscosity (V') was measured by performing a rotational sweep test on the sample at 150°C and a shear rate of 0.001 rad / s.

[0134] The above sample was manufactured in the form of a sheet with a diameter of 25 mm and a thickness of 1 mm using a hot press.

[0135] At this time, the strain hardening coefficient (χ) was obtained through V'' / (3 * V') according to the following equation 1:

[0136] [Formula 1]

[0137] Strain hardening coefficient (χ) = V'' / (3 * V')

[0138] (In Equation 1, V'' is the extensional viscosity of the decrosslinked polyolefin resin measured at a strain rate of 0.1 rad / s, and V' is the shear viscosity of the decrosslinked polyolefin resin measured at a shear rate of 0.001 rad / s).

[0139] ​

[0140] Additionally, the shear viscosity before and after de-crosslinking was measured at 0.001 rad / s, and the ratio of shear viscosities was obtained by the following equation 3:

[0141] [Formula 3]

[0142] 10 ≤ V0' / V' ≤ 700

[0143] (In Equation 3, V0' is the shear viscosity of the crosslinked polyolefin resin measured at a shear rate of 0.001 rad / s, and V' is the shear viscosity of the decrosslinked polyolefin resin measured at a shear rate of 0.001 rad / s).

[0144]

[0145] (3) Elongation rate (%)

[0146] Elongation was measured at a speed of 50 mm / min using Type V specimens of ASTM D638.

[0147]

[0148] (4) De-crosslinking index (DI)

[0149] After obtaining the strain hardening coefficient (χ) from Equation 1, it was calculated using Equation 2 below:

[0150] [Formula 2]

[0151] DI = E / (C * strain hardening coefficient (χ))

[0152] (In Equation 2, E is the elongation (%), the strain hardening coefficient (χ) is the value calculated in Equation 1, and C is the degree of cross-linking (%)).

[0153]

[0154] (5) Weight average molecular weight (Mw)

[0155] The polyolefin resin that underwent a decrosslinking reaction was dissolved in tetrahydrofuran (THF) solvent, filtered, and then the weight average molecular weight was measured using gel permeation chromatography (GPC).

[0156]

[0157] Crosslinking degree (%) Maximum value of strain hardening coefficient (χ) Elongation (%) Decrosslinking index (DI) V0' / V' Weight average molecular weight (Mw) Example 10.21.41264.44515.7155.7250354 Example 20.21.7903.22656.4770.3205585 Example 30.73.3285.8123.72407142323 Comparative example 115.2157.0430.2788.193230 Comparative example 20.25.1259253.92761.384710 Comparative example 30.2 Not measurable4-12328956865 Comparative example 40.13.9148.6381.0723.483609Comparative example 5153.7763.613.816.284118Comparative example 60.55.9400.68135.82750.1154462

[0158] As shown in Table 1 above, it can be confirmed that Examples 1-3 according to the present invention have a significantly low degree of crosslinking, a high elongation, a small maximum value of the strain hardening coefficient due to non-uniform branch chains, and excellent de-crosslinking properties.

[0159] On the other hand, Comparative Examples 1-2 secured a low degree of crosslinking, but it was confirmed that the maximum value of the strain hardening coefficient was large, the elongation was significantly low, and the decrosslinking property was low. In addition, Comparative Example 4 had a low degree of crosslinking, a small maximum value of the strain hardening coefficient, but a low elongation, and it was confirmed that the decrosslinking property was low. In addition, Comparative Example 5 had a small maximum value of the strain hardening coefficient, a high elongation, but a high degree of crosslinking, and it was confirmed that the decrosslinking property was low. In Comparative Example 6, it was confirmed that the maximum value of the strain hardening coefficient was large compared to the examples, even though a supercritical fluid was used.

[0160]

[0161] Figure 1 compares the strain hardening factor over time of Examples 1-3 and Comparative Examples 1-2 and 4-6. As shown in Figure 1, it can be confirmed that the maximum value of the strain hardening factor of Examples 1-3 was less than 5, but that of Comparative Examples 1, 2, and 6 exceeded 5. Through this, it can be seen that the decrosslinked polyolefin resin of the present invention has a low degree of crosslinking and a high elongation, and a small degree of strain hardening in which the elongational viscosity increases as the elongation progresses.

[0162]

[0163] Simple modifications or changes of the present invention can be easily implemented by a person having ordinary skill in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

[0164]

[0165] The decrosslinked polyolefin resin according to one embodiment of the present invention has industrial applicability.

Claims

1. As a decrosslinked polyolefin resin, The maximum value of the strain hardening factor (χ) defined by Equation 1 below is 5 or less, The cross-linking ratio is less than 10%, Decrosslinked polyolefin resin characterized by an elongation of 150% or more: [Formula 1] Strain hardening coefficient (χ) = V'' / (3 * V') (In Equation 1, V'' is the extensional viscosity of the decrosslinked polyolefin resin measured at 150°C and a strain rate of 0.1 rad / s, and V' is the shear viscosity of the decrosslinked polyolefin resin measured at 150°C and a shear rate of 0.001 rad / s).

2. In paragraph 1, The above-mentioned decrosslinked polyolefin resin is characterized in that the decrosslinking index (DI) defined by the following formula 2 is 50 or more: [Formula 2] DI = E / (C * strain hardening coefficient (χ)) (In Equation 2, E is the elongation (%), the strain hardening coefficient (χ) is the value calculated in Equation 1, and C is the degree of cross-linking (%)).

3. In paragraph 1, The above-mentioned decrosslinked polyolefin resin is a decrosslinked polyolefin resin characterized in that the weight average molecular weight (Mw) is 50,000 or more.

4. In paragraph 1, The above-mentioned decrosslinked polyolefin resin is a decrosslinked product of a peroxide-based crosslinked polyolefin resin, an electron beam-based crosslinked polyolefin resin, or a silane-based crosslinked polyolefin resin.

5. In paragraph 1, The above-mentioned de-crosslinked polyolefin resin is a de-crosslinked polyolefin resin that satisfies the following formula 3: [Formula 3] 10 ≤ V0' / V' ≤ 700 (In Equation 3, V0' is the shear viscosity of the crosslinked polyolefin resin measured at a shear rate of 0.001 rad / s, and V' is the shear viscosity of the decrosslinked polyolefin resin measured at a shear rate of 0.001 rad / s).

6. In paragraph 1, The above-mentioned decrosslinked polyolefin resin is a decrosslinked polyolefin resin that is twin-screw extruded in the presence of a subcritical fluid or a supercritical fluid.

7. A composition comprising a de-crosslinked polyolefin resin according to any one of claims 1 to 6.

8. In the 7th paragraph, the composition further comprises a crosslinked polyolefin resin.

9. A method for producing a decrosslinked polyolefin resin, comprising a step of twin-screw extruding a crosslinked polyolefin resin so that the maximum value of the strain hardening factor (χ) defined by the following equation 1 is 5 or less and the decrosslinking index (DI) defined by the following equation 2 is 50 or more in the presence of a subcritical fluid or a supercritical fluid: [Formula 1] Strain hardening coefficient (χ) = V'' / (3 * V') (In Equation 1, V'' is the extensional viscosity of the decrosslinked polyolefin resin measured at 150°C and a strain rate of 0.1 rad / s, and V' is the shear viscosity of the decrosslinked polyolefin resin measured at 150°C and a shear rate of 0.001 rad / s.) [Formula 2] DI = E / (C * strain hardening coefficient (χ)) (In Equation 2, E is the elongation (%), the strain hardening coefficient (χ) is the value calculated in Equation 1, and C is the degree of cross-linking (%)).

10. In paragraph 9, The above-mentioned de-crosslinked polyolefin resin has a crosslinking degree of 10% or less, A method for producing a decrosslinked polyolefin resin, characterized in that the elongation is 150% or more.

11. In paragraph 9, A method for producing a decrosslinked polyolefin resin, characterized in that the above-mentioned decrosslinked polyolefin resin has a weight average molecular weight (Mw) of 50,000 or more.

12. In paragraph 9, A method for producing a decrosslinked polyolefin resin, wherein the crosslinked polyolefin resin includes a crosslinked polyolefin resin by peroxide, a crosslinked polyolefin resin by electron beam, or a silane crosslinked polyolefin resin.

13. In paragraph 9, A method for producing a decrosslinked polyolefin resin, wherein the above-mentioned twin-axis extrusion is performed at a temperature of 230°C or higher and 350°C or lower.

14. In paragraph 9, The above-mentioned decrosslinked polyolefin resin satisfies the following formula 3, and a method for producing a decrosslinked polyolefin resin: [Formula 3] 10 ≤ V0' / V' ≤ 700 (In Equation 3, V0' is the shear viscosity of the crosslinked polyolefin resin measured at a shear rate of 0.001 rad / s, and V' is the shear viscosity of the decrosslinked polyolefin resin measured at a shear rate of 0.001 rad / s).

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