KR102486846B1 - An olefin based polymer - Google Patents

Abstract

This application is an invention related to olefin-based polymers. The polymer is configured to have a predetermined relationship with respect to the content of tie molecules, entanglement molecular weight (M _e ) and the content of ultra-high molecular weight components, and thus the polymer of the present application has excellent long-term durability It can be used when manufacturing heating tubes as required.

Description

An olefin based polymer}

This application relates to olefinic polymers.

Since pipes for plumbing used for heating pipes are constructed inside a building, they must have excellent long-term durability to prevent leakage due to cracks. ISO 9080 and ISO 16770 are widely known long-term durability evaluation methods for plumbing pipes. ISO 9080 is a method of estimating the pressure at which cracks are expected to occur after 50 years by measuring the crack occurrence time for one year or more according to the temperature and pressure of water passing through the pipe and extrapolating it. Products certified for long-term durability by ISO 9080 have environmental stress crack resistance (ESCR) measured by Full Notch Creep Test (FNCT) according to ISO 16770 at 4.0 MPa stress and 80°C temperature. This is about 2,000 hours or more. That is, the product has durability to the extent that the sample is broken only after 2,000 hours or more have elapsed by the above method.

It is thought that the long-term durability of the pipe used for the above application is affected by the properties of the resin used to form the pipe. Therefore, a polymer-related design criterion capable of securing long-term durability of the pipe is required.

One object of the present application is to provide a polymer that can be used to manufacture pipes for heating pipes with excellent long-term durability.

The above and other objects of the present application can all be solved by the present application described in detail below.

As an example of the present application, the present application relates to an olefin-based polymer. The polymer may be used for a pipe forming a moving path of a fluid or the like, and may be mainly used for forming a heating pipe. Since the polymer satisfies predetermined conditions and/or configurations described below, it has excellent long-term durability, which can be confirmed through, for example, environmental stress crack resistance evaluation.

In the present application, as the design factors of the olefin-based polymer, tie molecule content, entanglement molecular weight (M _e ), and ultra-high molecular component content may be used.

In the present application, a tie molecule, which is one of the design factors of a polymer, means a polymer that connects between crystals of an amorphous polymer resin. In amorphous polymers, crystals having a lamellar structure are formed by chain folding below the crystallization temperature. At this time, when there is a polymer structure that can create a defect in the crystal structure, for example, an α-olefin or a long chain branch (LCB), the corresponding portion does not form a crystal and remains amorphous. On the other hand, since a lamellar can be formed in a part where no α-olefin or LCB structure exists, one polymer chain can form a crystalline-amorphous-crystal structure. In such a structure, the amorphous portion plays a role in connecting crystals to crystals, and it is referred to as a tie molecule. The higher the molecular weight of the polymer and the longer the polymer chain, the higher the probability of tymolecular formation. As such, it is thought that the higher the content of Thai molecules, the stronger the connection between the crystal structures, making it difficult for cracks to occur and propagate. Considering this point, in the present application, the content of tymolecule is used as a factor in designing the polymer used for the above purpose. At this time, the content of the thymolecule means the % ratio of the (polymer) components forming the thymolecule based on the weight of 100 of the total polymer, that is, the weight%. The content of tie molecules can be measured as described below.

Entanglement molecular weight (M _e ), another factor used in this application, is that one polymer chain is entangled with surrounding polymers or itself to form an entanglement point that functions as a physical crosslink. When, it means the average molecular weight between these entanglement points. Since the molecular weight of the polymer is high and the length of the polymer chain increases, the probability of generating an entanglement point increases, so the entanglement molecular weight decreases. Since the degree of entanglement of the polymer increases as the entanglement molecular weight decreases, it is thought that the resistance to external force increases. With this in mind, this application uses entanglement molecular weight as a factor in the design of polymers used for this purpose. Entanglement molecular weight can be measured as described below.

Another of the factors used in this application is the content of ultra-high molecular weight components. At this time, the ultra-high molecular weight means a case where the mass average molecular weight (Mw) is 1 million or more, and the content of the ultra-high molecular weight component is the % ratio of (polymer) component having a mass average molecular weight of 1 million or more based on the weight of 100 of the total polymer, that is, the weight means %. Since the number of polymers having long polymer chains increases as the content of the ultra-high molecular weight component increases, it is thought that the entanglement of the polymer chains and the content of thymolecules also increase. Considering this point, the present application uses the content of the ultra-high molecular weight component as a factor in designing the polymer used for this purpose. The content of the ultra-high molecular weight component can be measured as described below.

The inventors of the present application have confirmed that, when the olefin-based polymer is designed to satisfy a predetermined relationship with respect to the above factors, it is possible to provide a resin for a heating pipe having excellent long-term durability. Specifically, the olefin-based polymer of the present application may be an olefin-based polymer that satisfies at least two or more of the following conditions [A] to [C].

[A] The content of tie molecule is 10 wt% or more

[B] entanglement molecular weight (Me) of 17,000 g/mol or less

[C] The content of a component having a mass average molecular weight (Mw) of 1 million or more is 2.5 wt% or more

When at least two or more conditions of [A] to [C] are satisfied, environmental stress crack resistance (ESCR) measured by a full notch creep test (FNCT) according to ISO 16770 at 4.0 MPa and 80 ° C. ) can show excellent long-term durability properties. For example, time characteristics described below may be satisfied.

In one example, the polymer may further satisfy the condition that the content of tie molecules is 30 wt% or less, 25 wt% or less, or 20 wt% or less with respect to the condition [A]. When designing a polymer for the predetermined purpose, an increase in the content of tymolecule may be considered in consideration of the significance of the content of tymolecule as described above. In order to increase the content of tymolecule, the density of the polymer must be lowered or the content of the high molecular weight component must be increased. However, when the density decreases, the pressure resistance performance of the final pipe product decreases, and when the content of the polymer component increases, the viscosity increases and the processability deteriorates. Do.

In another example, the polymer has an entanglement molecular weight (Me) of 1000 g / mol or more, 2000 g / mol or more, 3000 g / mol or more, 4000 g / mol or more, or 5000 g / mol or more conditions may be further satisfied. When designing a polymer for a given purpose, a decrease in the molecular weight may be considered in consideration of the significance of the content of the entangled molecular weight as described above. However, when the entanglement molecular weight is too low, since the content of the high molecular weight component is high, processability is deteriorated. In addition, since breakage easily occurs in the stretching process to meet dimensions such as diameter or thickness after extrusion of the manufactured pipe, there is a problem that the production line is lowered due to the need to stretch at a low speed. Therefore, it is preferable to have a molecular weight equal to or higher than the above range.

In another example, the polymer is further subjected to the condition that the content of the component having a mass average molecular weight (Mw) of 1 million or more in relation to the condition [C] is 20 wt% or less, 15 wt% or less, or 10 wt% or less can be satisfied When the content of the ultra-high molecular weight component exceeds the above range, processability may be deteriorated.

In another example, the polymer may satisfy all of the conditions [A] to [C]. When all of the above three conditions are satisfied, more excellent long-term durability can be secured.

Types of monomers for forming the olefin-based polymer are not particularly limited. For example, the olefin-based polymer may be formed from a monomer mixture including ethylene, butylene, propylene, or α-olefin-based monomers. That is, the polymer of the present application may be prepared by polymerizing one or more of the above monomers. At this time, the type of the α-olefin-based monomer is not particularly limited. For example, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene , 1-hexadecene, 1-octadecene or 1-eicosene may be used, but is not particularly limited thereto.

In one example, the monomer mixture may include two or more monomers selected from ethylene, butylene, propylene, and α-olefin monomers. At this time, two or more monomers included in the monomer mixture may be different from each other, and the types of α-olefin-based monomers are the same as those listed above.

In one example, the olefin-based polymer may include ethylene as a main component. In this application, the main component monomer in relation to the components of the polymer may mean a case in which the content of the main component monomer exceeds 50 wt% based on 100 content of the total monomers used to form the polymer. The upper limit of the main component monomer content is not particularly limited, but may be, for example, 95 wt% or less, 90 wt% or less, 85 wt% or less, 80 wt% or less, 75 wt% or less, or 70 wt% or less. In this case, the monomer mixture may include, in addition to ethylene as a main component, at least one monomer selected from butylene, propylene, and α-olefin-based monomers as a copolymerizable monomer. The copolymerizable monomer may be used in the monomer mixture in an amount remaining except for the content of ethylene, which is the main component monomer.

In one example, 1-butene (1-C4) may be used as a copolymerization monomer for forming the olefin-based polymer. Specifically, there are cases in which short monomers, such as 1-butene, are used due to the characteristics of polymerization equipment or the supply and demand of raw materials. However, in this case, long-term durability may be lowered compared to products manufactured using relatively long copolymer monomers, such as 1-hexene (1-C6) or 1-octene (1-C8). However, when the conditions of the present application described above are satisfied, excellent long-term durability can be secured even when a relatively short copolymer monomer such as 1-butene is used. The content of 1-butene used is not particularly limited, but, for example, as a result of FT-IR analysis, it may be used to satisfy the range of about 7.0 to 10.1/1,000 C.

Polymers satisfying the above conditions and configurations may have an environmental stress cracking resistance (ESCR) of 1500 hours or more as measured by a full notch creep test (FNCT) according to ISO 16770 at 4.0 MPa and 80 °C. More preferably, the polymer may have an environmental stress cracking resistance (ESCR) of 2000 hours to 8000 hours as measured by a full notch creep test (FNCT) under the same conditions and methods.

According to the present application, an olefin-based polymer structure having excellent long-term durability can be designed usefully, and a pipe for plumbing with excellent long-term durability can be provided.

Hereinafter, the present application will be described in detail through examples. However, the protection scope of the present application is not limited by the examples described below.

Related physical properties measured in the following experimental examples were measured according to the following method.

<Measurement method>

* FNCT ( Full Notch Creep Test ) Actual value : For the polymers of Preparation Examples 1 to 14 prepared below, a full notch creep test was performed according to ISO 16770 at a stress of 4.0 MPa and a temperature of 80 ° C. Specifically, the specimen for performing the FNCT is a rectangular parallelepiped with a size of 10 X 10 X 100 mm, obtained by milling a plate material having a thickness of 15 mm. Thereafter, notches with a depth of 1.5 mm were formed on the four sides of the specimen, a stress of 4.0 MPa was applied to the specimen in a 10% Igepal solution at 80 ° C, and the time taken until fracture occurred in the specimen was measured. Based on the measured time, the characteristics of the resin were qualitatively classified according to the following criteria.

<Qualitative Classification of FNCT Measured Values>

- Over 2,000 hours: excellent

- Between 1,500 hours and less than 2,000 hours: Somewhat good

- Between 1,000 hours and less than 1,500 hours: Normal

- 400 hours to less than 1,000 hours: somewhat worse

- Less than 400 hours: bad

* Content of tie molecule: Molecular weight distribution, melting point (Tm), and mass fraction crystallinity were calculated in the following manner, and the content of tie molecule was calculated from these values.

- Molecular weight distribution: Using Agilent's PL-SP260, 10 mg of the sample to be measured was dissolved in 1,2,4-Trichlorobenzene containing 0.0125% BHT at 160 ° C for 10 hours, pre-treated, and high-temperature GPC (Gel Permeation Chromatography) GPC curves were obtained using phosphorus PL-GPC220.

- Melting point and mass fraction crystallinity: Place 5 mg of the sample to be measured on an Al Pan, cover with Al Lid, punch and seal, and heat from 50 ℃ to 190 ℃ at 10 ℃ / min using TA's DSC Q20 (Cycle 1), after isothermal at 190 °C for 5 minutes, cooled at 10 °C/min to 50 °C, then heated again at 10 °C/min to 190 °C after isothermal at 50 °C for 5 minutes (Cycle 2). Melting point and mass fraction crystallinity were calculated from the temperature (Tm) and area (ΔH) of the DSC curve peak in the range of 60 ° C to 140 ° C in Cycle 2.

Tm: temperature of the DSC curve peak

Mass fraction crystallinity: ΔH/293.6 X 100 (293.6: ΔH when 100% Crystal)

- Calculation of content of thymolecule: The content of thymolecule was calculated from the area of a thymolecule distribution graph in which the x-axis is the molecular weight M and the y-axis is n·P·dM. The graph is calculated from the GPC curve and DSC measurement results. Regarding the y-axis, n is the number of polymers having a molecular weight of M, and can be obtained as (dw/dlogMw)/M from the data of a GPC curve in which the x-axis is logMw and the y-axis is dw/dlogMw. In addition, P is the probability that a polymer having a molecular weight of M forms a thymolecule, which can be calculated from Equations 1 to 3 below, and dM is the interval between the x-axis (molecular weight M) data of the GPC curve.

[Equation 1]

In Equation 1, r is the end to end distance of a random coil, b ² is 3/2r ² , and l _c is the crystal thickness from Equation 2 below. and l _a is the amorphous thickness obtained from Equation 3 below.

[Equation 2]

In Equation 2, T ^o _m is 415K, σ _e is 60.9 x 10 ^-3 J/m ² , and Δh _m is 2.88 x 10 ³ J/m ³ .

[Equation 3]

In Equation 3, ρ _c is the density of crystalline and is 1,000 kg/m ³ , ρ _a is the density of amorphous phase and is 852 kg/m ³ , and ω ^c is the mass fraction crystallinity (weight fraction crystallinity) was confirmed from the DSC results.

* Calculation of entanglement molecular weight (M _e ) : Using a rotational rheometer, storage of each sample at a temperature of 150 ℃ to 230 ℃, 0.05 to 500 rad / s angular frequency (Angular Frequency), 0.5% strain (Strain) conditions The elastic modulus and the loss elastic modulus were measured, and the entangled molecular weight was calculated according to the following theoretical formula from the plateau elastic modulus (G _N ⁰ ) obtained here. However, in the following theoretical equation, ρ means density (kg/m ³ ), R means gas constant (8.314 Pa·m ³ /mol·K), and T means absolute temperature (K).

[theoretical formula]

M _e = (ρRT) / G _N ⁰

* Measurement and calculation of the content of the ultra-high molecular weight component: From the molecular weight distribution analysis result of the sample, the area ratio (%) of the portion having a molecular weight of 1 million or more was calculated relative to the total area.

Experimental example

Preparation Example 1: In the hexane slurry CSTR process, a resin was polymerized while supplying ethylene, hydrogen, and 1-butene at a predetermined input rate using a metallocene catalyst capable of creating a bimodal molecular weight distribution. The prepared resin has a density of 0.9365 g/cm ³ measured according to ASTM D 1505. And, according to ASTM D 1238, the MI (melting index) measured under the conditions of 190 ° C and 2.16 kg / 10 min was 0.02.

Preparation Example 2: A resin was prepared in the same manner as in Preparation Example 1, except that a metallocene catalyst of a different type from Preparation Example 1 was used. The density of the prepared resin is 0.9396 g/cm ³ , and the MI was 0.26.

Preparation Example 3: A resin was prepared in the same manner as in Preparation Example 2, except that the feed rate of the raw material was differently adjusted. The density of the prepared resin is 0.9392 g/cm ³ , and the MI was 0.34.

Preparation Example 4: A resin was prepared in the same manner as in Preparation Example 2, except that the feed rate of the raw material was differently adjusted. The density of the prepared resin is 0.9358 g/cm ³ , and the MI was 0.75.

Preparation Example 5: A resin was prepared in the same manner as in Preparation Example 2, except that the feed rate of the raw material was differently adjusted. The density of the prepared resin is 0.9363 g/cm ³ , and the MI was 0.27.

Preparation Example 6: A resin was prepared in the same manner as in Preparation Example 2, except that the feed rate of the raw material was differently adjusted. The density of the prepared resin is 0.9396 g/cm ³ , and the MI was 0.32.

Preparation Example 7: A resin was prepared in the same manner as in Preparation Example 2, except that the feed rate of the raw material was differently adjusted. The density of the prepared resin is 0.9365 g/cm ³ , and the MI was 0.60.

Preparation Example 8: A resin was prepared in the same manner as in Preparation Example 2, except that the feed rate of the raw material was differently adjusted. The density of the prepared resin was 0.9367 g/cm ³ , and the MI was 0.47.

Preparation Example 9: A resin was prepared in the same manner as in Preparation Example 2, except that the feed rate of the raw material was differently adjusted. The density of the prepared resin is 0.9369 g/cm ³ , and the MI was 0.38.

Preparation Example 10: A resin was prepared in the same manner as in Preparation Example 2, except that the feed rate of the raw material was differently adjusted. The density of the prepared resin is 0.9364 g/cm ³ , and the MI was 0.48.

Preparation Example 11: Density of 0.9362 g/cm ³ And, a resin was prepared in the same manner as in Preparation Example 2, except that the MI measured under the same conditions was 0.43.

Preparation Example 12: Density of 0.9363 g/cm ³ And, a resin was prepared in the same manner as in Preparation Example 2, except that the MI measured under the same conditions was 0.26.

Preparation Example 13: Density of 0.9362 g/cm ³ And, a resin was prepared in the same manner as in Preparation Example 2, except that the MI measured under the same conditions was 0.44.

Preparation Example 14: Density of 0.9363 g/cm ³ And, a resin was prepared in the same manner as in Preparation Example 2, except that the MI measured under the same conditions was 0.39.

Example

With respect to the samples prepared in each preparation example, the content of tymolecules, entangled molecular weight, and ultrahigh molecular weight components were measured according to the above method. Separately, the environmental stress cracking resistance measured by FNCT was measured for the samples prepared in each of the above preparation examples. The results are shown in Table 1.

[Table 1]

Looking at Table 1, it can be seen that when at least two or more of the conditions specified in the present application are satisfied, a polymer for a heating pipe having excellent long-term durability can be designed.

Claims (11)

An olefin-based polymer that satisfies at least two or more of the following conditions [A] to [C]:
[A] The content of tie molecule is 10 wt% or more
[B] entanglement molecular weight (Me) of 17,000 g/mol or less
[C] The content of a component having a mass average molecular weight (Mw) of 1 million or more is 2.5 wt% or more The olefin-based polymer according to claim 1, which further satisfies the condition that the content of tie molecules is 25 wt% or less in relation to the condition [A]. The olefin-based polymer according to claim 1, further satisfying the condition that the entanglement molecular weight (Me) is 3,000 g/mol or more in relation to the condition [B]. The olefin-based polymer according to claim 1, further satisfying the condition that the content of the component having a mass average molecular weight (Mw) of 1 million or more in relation to the condition [C] is 15 wt% or less. The olefin-based polymer according to claim 1, which satisfies all of the conditions [A] to [C]. The olefin-based polymer according to claim 1, wherein the olefin-based polymer is formed from a monomer mixture including ethylene, butylene, propylene, or an α-olefin monomer. The olefin-based polymer according to claim 6, wherein the monomer mixture contains more than 50% by weight of ethylene based on the total amount of monomers. 8. The method of claim 7, wherein the monomer mixture is 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene. An olefin-based polymer further comprising at least one selected from sen, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene. The olefin-based polymer according to claim 8, wherein the monomer mixture includes ethylene and 1-butene. The olefin-based polymer according to claim 1, which has an environmental stress crack resistance (ESCR) of 1500 hours or more as measured by a full notch creep test (FNCT) according to ISO 16770 at 4.0 MPa and 80 ° C. The olefin-based polymer according to claim 1, which has an environmental stress crack resistance (ESCR) of 2000 hours to 8000 hours as measured by a full notch creep test (FNCT) according to ISO 16770 at 4.0 MPa and 80 ° C.