WO2023155574A1 - Highly insulative, low-temperature-resistant, environmental-stress-cracking-resistant hdpe material, preparation method therefor and use thereof - Google Patents

Abstract

The present invention provides a highly insulative, low-temperature-resistant, environmental-stress-cracking-resistant HDPE material, a preparation method therefor and use thereof. The HDPE material of the present invention comprises the following components: 35-70 parts by weight of HDPE, 5-10 parts by weight of a hyperbranched polyacrylate oligomer, 10-20 parts by weight of PB, 10-20 parts by weight of HDPE-g-MAH, 5-10 parts by weight of POE, and 0-2 parts by weight of an additional auxiliary, wherein the number average molecular weight of the hyperbranched polyacrylate oligomer is 1000-9000. The time to cracking of the prepared material of the present invention at 70 °C under an internal air pressure of 5 MPa is 2000 h or above; the propane gas permeability is <0.1％; at -40 °C, the notched impact strength of the material is 15 kJ/m 2 or above and can reach as high as 16.4 kJ/m 2. The material can be used to manufacture products that require high airtightness, such as liquefied gas tanks.

Description

A kind of HDPE material with high barrier, low temperature resistance and environmental stress cracking resistance and its preparation method and application technical field

The invention belongs to the technical field of modified plastics, and in particular relates to a high-barrier, low-temperature-resistant, and environmental-stress-crack-resistant HDPE material and a preparation method and application thereof.

Background technique

Traditional liquefied gas cylinders are mainly steel cylinders, but steel cylinders have disadvantages such as heavy weight, difficult processing, and high cost, and steel cylinders are conductive, so it is impossible to add positioning and stress sensing systems to steel cylinders, and it is impossible to form an Internet of Things and track user liquefied gas in real time. usage.

Due to its light weight, electrical insulation, convenient processing and molding, and low price, HDPE has been selected as the material for the new generation of liquefied gas cylinders using plastic instead of steel. However, the traditional HDPE resin has poor resistance to environmental stress cracking. Since the HDPE molecular chain has no branches or side groups, during long-term use, the molecular chain will slip due to stress or solvent immersion, which will eventually lead to cracking of the product. In addition, HDPE is a non-polar material. According to the principle of similar compatibility, when HDPE is in contact with organic small molecule gases such as oil and gas, propane gas, and methane gas for a long time, the organic small molecule gas will immerse into the gap between HDPE molecular chains, resulting in The HDPE material swells, which affects the airtightness of the liquefied gas cylinder. At the same time, in the actual use process, it is inevitable to encounter bumps. Therefore, it is also necessary for the liquefied gas cylinder to have a certain degree of toughness, especially low temperature toughness.

Therefore, HDPE materials need to be modified to improve the above performance. Most of the existing modifications are dedicated to the improvement of a single performance. For example, there is a patent "A Super Tough Environmental Stress Cracking Resistant High-Density Polyethylene and Its Preparation Method", which discloses the compounding of PP and HDPE to improve the environmental stress cracking resistance of HDPE, but PP has low impact strength and poor toughness at low temperatures. , and does not have barrier properties to organic small molecule gases; there are also studies that show that ultra-high molecular weight HDPE materials have better low-temperature toughness, higher melt strength, and better environmental stress cracking resistance than ordinary HDPE materials, but they cannot be obtained from It fundamentally solves the problem of HDPE resistance to environmental stress cracking. With the prolongation of use time, stress cracking will also occur, and the melting index of the material is too low to be suitable for injection molding; the patent "ethylene-vinyl alcohol copolymer and high-density polyethylene Blended material and its preparation method》By adding EVOH polar substances and tougheners to HDPE, the barrier and toughness of the material are improved, but the compatibility between EVOH and HDPE is poor, and a large amount of compatibilizing agent needs to be added The addition of a large amount of compatibilizer will also reduce the mechanical properties (such as toughness) of the material to a certain extent.

Therefore, there is currently no modified HDPE material on the market that can simultaneously take into account the three properties of high barrier, low temperature resistance, and environmental stress cracking resistance. The high-barrier HDPE material is suitable for the production of products with high air-tightness requirements such as liquefied gas cylinders.

Contents of the invention

The object of the present invention is to overcome the defect that the barrier performance, low temperature resistance and environmental stress cracking resistance of HDPE materials in the prior art cannot be improved simultaneously, and provide a HDPE material with high barrier, low temperature resistance and environmental stress cracking resistance.

Another object of the present invention is to provide a method for preparing the high-barrier, low-temperature-resistant, and environmental-stress-crack-resistant HDPE material.

Another object of the present invention is to provide the application of the high-barrier, low-temperature-resistant, and environmental-stress-crack-resistant HDPE material in the fields of gas storage and transportation.

To achieve the above object, the present invention adopts the following technical solutions:

A high-barrier, low-temperature-resistant, and environmental-stress-crack-resistant HDPE material, comprising components calculated in parts by weight as follows:

Wherein, the number average molecular weight of the hyperbranched polyacrylate oligomer is 1000-9000.

In the present invention, the hyperbranched polyacrylate oligomer has a hyperbranched structure, and the branched chain structure makes HDPE (high density polyethylene) molecular chains entangle more easily, and the ethyl (—C) existing in PB (polybutene) ₂ H ₅ ) side group structure can make the entanglement of molecular chains more firm and effectively inhibit the disentanglement of molecular chains. The synergy between hyperbranched polyacrylate oligomers and PB can make the material’s environmental resistance The stress cracking performance is more prominent; at the same time, the addition of hyperbranched polyacrylate oligomers can also improve the melt strength of HDPE, increase the force between HDPE molecular chains, and promote the entanglement between HDPE molecules, making the material further Provides longer-term environmental stress cracking resistance.

The maleic anhydride graft in HDPE-g-MAH (high-density polyethylene grafted maleic anhydride) has polarity, which can improve the barrier performance of the material. At the same time, the HDPE chain segment in HDPE-g-MAH can also interact with the matrix Hydrogen bonds are formed between resins (HDPE), which can effectively inhibit the immersion of non-polar organic small molecule gases and liquids. In addition, the existence of hydrogen bonds forms a cross-linked network structure in the system, further inhibits the disentanglement of HDPE molecular chains, and improves the environmental stress resistance and cracking resistance of the material. Moreover, HDPE-g-MAH has good compatibility with HDPE, without adding additional compatibilizers, and will not have a negative impact on the mechanical properties of the material (especially low-temperature toughness). It can also be used as a compatibilizer of the system to a certain extent to improve the compatibility between POE (polyolefin elastomer) and HDPE, and then improve the low-temperature toughness of the material by POE.

Therefore, in the present invention, the synergistic effect between the hyperbranched polyacrylate oligomer, PB, and HDPE-g-MAH makes the material have significant environmental stress cracking resistance; the synergistic effect of HDPE-g-MAH and matrix resin The barrier performance of the material is further improved; at the same time, it also has good low-temperature toughness.

Conventional injection molding grade HDPE can be used in the present invention, and the melt flow rate of said HDPE under the conditions of 190°C and 2.16kg is generally in the range of 5-15g/10min, which is more conducive to processing and uniformity of other components in the HDPE matrix dispersion.

In order to further improve the processability and dispersion uniformity of the material, the melt flow rate of the HDPE under the conditions of 190° C. and 2.16 kg is more preferably 5˜10 g/10 min.

It should be noted that the melt flow rate of raw materials in the present invention is obtained according to the ISO 1133-1:2011 standard method test.

The inventors of the present invention have also found through further research that for hyperbranched polyacrylate oligomers, the molecular weight is too low to improve the environmental stress cracking resistance of the material; if the molecular weight is too high, the viscosity of hyperbranched polyacrylate oligomers is too high. High, poor compatibility with HDPE, more prone to cracking during long-term use, and the environmental stress cracking resistance of the material becomes worse. The hyperbranched polyacrylate oligomer with appropriate molecular weight can improve the environmental stress cracking resistance of the material. The inventors found that the number average molecular weight of the hyperbranched polyacrylate oligomer is in the range of 1000-9000, which can have a more significant improvement effect.

In order to further improve the performance of the material, preferably, the number average molecular weight of the hyperbranched polyacrylate oligomer is 4500-8000, more preferably 5500-6000. In the present invention, the number average molecular weight of the raw material is obtained by testing according to the method of "QJ 1870-1990".

Preferably, the hyperbranched acrylate oligomer is a hexafunctional urethane acrylate oligomer, a difunctional urethane acrylate oligomer, a urethane acrylate oligomer, a hyperbranched polyester acrylate oligomer, One or a combination of group polyurethane acrylate oligomers or UV hyperbranched acrylic resins.

Conventional commercially available PB can be used in the present invention, and the number average molecular weight of PB can be 30,000-330,000.

Conventional commercially available HDPE-g-MAH can be used in the present invention. Generally, the graft ratio of MAH (maleic anhydride) in commercially available HDPE-g-MAH is 0.5-1 wt%. The grafting rate is obtained by testing the infrared method. The method is: test the infrared of the sample, and compare the ratio of the carbonyl absorbance in the infrared spectrum to the absorbance of the polyethylene characteristic peak, that is, the ratio of the absorbance at 1712cm ^-1 to 719cm ^-1 .

In order to further improve the compatibility with HDPE and improve the low temperature resistance of the material, preferably, one of the POE ethylene-propylene copolymer elastomer, ethylene-butylene copolymer elastomer or ethylene-octene copolymer elastomer Several combinations.

Further preferably, the POE is an ethylene-octene copolymerized elastomer.

All conventional commercially available POEs can be used in the present invention. The melt flow rate of the POE under the conditions of 190° C. and 2.16 kg is generally in the range of 0.5-13 g/10 min.

In order to further improve the processability of the material, further preferably, the melt flow rate of the POE under the conditions of 190° C. and 2.16 kg is 0.5˜3 g/10 min.

According to the processing or use requirements of the product, a small amount of other additives may also be added, including but not limited to antioxidants and/or lubricants.

Optionally, the antioxidant is one or more combinations of phenolic antioxidants or thioether antioxidants, preferably phenolic antioxidants and thioether antioxidants in a weight ratio of The compound antioxidant obtained by compounding 1:1.

Preferably, the phenolic antioxidant is one or a combination of antioxidant 1010, antioxidant 1076 or antioxidant 1098.

Preferably, the thioether antioxidant is one or a combination of antioxidant 412S or antioxidant DTBP.

Preferably, the lubricant is a stearate lubricant, specifically one or a combination of calcium stearate or zinc stearate.

The preparation method of the HDPE material with high barrier, low temperature resistance and environmental stress cracking resistance comprises the following steps:

After uniformly mixing HDPE, hyperbranched polyacrylate oligomer, PB, HDPE-g-MAH, POE and other additives, it is obtained by melting and extruding under the condition of 170-210°C.

Preferably, the mixing is performed in a high-speed mixer, and the rotation speed of the high-speed mixer is 200-250 rpm.

Preferably, the extrusion is carried out in a twin-screw extruder, the length-to-diameter ratio (L/D) of the screw of the twin-screw extruder is 48:1, and the rotational speed of the twin-screw extruder is 250- 300rpm.

The application of the high-barrier, low-temperature-resistant, and environmental-stress-crack-resistant HDPE material in the fields of gas storage and transportation is also within the protection scope of the present invention.

Specifically, the high-barrier, low-temperature-resistant, and environmental-stress-crack-resistant HDPE material is used to prepare liquefied gas cylinders, gas cylinders or natural gas pipelines.

Compared with prior art, the beneficial effect of the present invention is:

The invention provides a HDPE material with high barrier, low temperature resistance, and environmental stress cracking resistance. Through the synergistic effect between hyperbranched polyacrylate oligomers, PB, and HDPE-g-MAH, the material has remarkable environmental resistance Stress cracking performance; the synergistic effect of HDPE-g-MAH and matrix resin further improves the barrier performance of the material; it also has good low temperature toughness. The material prepared by the present invention has a cracking time of more than 2000h at 70°C and an internal pressure of 5MPa; the transmission rate of propane gas is less than 0.1%; at -40°C, the notched impact strength of the material is ^above 15kJ/m2 , up to 16.4kJ/m ² . The properties of the HDPE material in the invention can be used to prepare products such as liquefied gas cylinders that require high airtightness.

Detailed ways

The present invention will be further described below in conjunction with specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the technical field. Unless otherwise specified, the reagents and materials used in the present invention are commercially available.

Embodiments of the invention employ the following raw materials:

HDPE resin:

HDPE-1: DMDA 8008, with a melt flow rate of 6g/10min at 190°C and 2.16kg, purchased from Dushanzi Petrochemical;

HDPE-2: HDPE 2911, with a melt flow rate of 12g/10min at 190°C and 2.16kg, purchased from Fushun Petrochemical;

Hyperbranched Acrylate Oligomers:

1#: Etercure 6145-100, the number average molecular weight is 1000-2000, purchased from Changxing, Taiwan;

2#: Etercure 6113, the number average molecular weight is 4500-5000, purchased from Changxing, Taiwan;

3#: Etercure 6148, the number average molecular weight is 5500-6000, purchased from Changxing, Taiwan;

4#: Etercure DR-E528, the number average molecular weight is 7500-8000, purchased from Changxing, Taiwan;

5#: HyPer C100, the number average molecular weight is 8500-9000, purchased from Wuhan Hyperbranched Resin Co., Ltd.;

6#: Etercure 6126, the number average molecular weight is 100-500, purchased from Changxing, Taiwan;

7#: HD-2280, the number average molecular weight is 15000-20000, purchased from Changzhou Houding;

PB:

1#: KTAR05, the number average molecular weight is 100000-120000, purchased from Basel;

2#: 8640M, the number average molecular weight is 60000-80000, purchased from Basel;

HDPE-g-MAH:

1#: K2C, MAH graft rate 0.9wt%, purchased from Keaisi;

2#: PE-G-3, MAH graft rate 0.6wt%, purchased from Nanjing Deba;

POE:

1#: Ethylene-octene copolymerized elastomer, POE 8157, with a melt flow rate of 0.5g/10min at 190°C and 2.16kg, purchased from Dow, USA;

2#: Ethylene-octene copolymerized elastomer, POE 8450G, with a melt flow rate of 3g/10min at 190°C and 2.16kg, purchased from Dow, USA;

3#: Ethylene-butylene copolymerized elastomer, POE 7467, with a melt flow rate of 1.2g/10min at 190°C and 2.16kg, purchased from Dow, USA;

4#: Ethylene-propylene elastomer, VISTAMAXX 6102, with a melt flow rate of 1.3g/10min at 190°C and 2.16kg, purchased from Exxon;

5#: Ethylene-octene copolymerized elastomer, POE 8137, with a melt flow rate of 13g/10min at 190°C and 2.16kg, purchased from Dow, USA;

other:

Ethylene-vinyl alcohol copolymer (EVOH): EVAL E151B, purchased from Kuraray, Japan;

Other additives:

Antioxidant 1010: commercially available;

Antioxidant DTBP: commercially available;

Calcium stearate: commercially available.

It should be noted that, in the present invention, other auxiliary agents used in each embodiment and comparative example are the same.

Examples 1-16

This example provides a series of high-barrier, low-temperature-resistant, and environmental-stress-cracking-resistant HDPE materials, which are prepared according to the formulations in Tables 1-2 and the preparation method including the following steps:

Add HDPE, hyperbranched polyacrylate oligomer, PB, HDPE-g-MAH, POE and other additives into a high-speed mixer and mix for 5 minutes. The speed of the high-speed mixer is 200-250rpm, and the mixture is obtained after mixing evenly. Then put it into the twin-screw extruder (screw length-to-diameter ratio is 48:1), at 170-210°C (the temperature in the first zone is 170-180°C, the temperature in the second zone is 190-200°C, the temperature in the third zone is 190-200°C, The temperature in the fourth zone is 190～200℃, the temperature in the fifth zone is 190～200℃, the temperature in the sixth zone is 190～205℃, the temperature in the seventh zone is 190～205℃, the temperature in the eighth zone is 200～210℃, the temperature in the ninth zone is 200～210℃), 250 It is obtained by melting, extruding, and pelletizing (underwater pelletizing) at ~300rpm.

Table 1 The content of each component in the HDPE material with high barrier, low temperature resistance and environmental stress cracking resistance of Examples 1-8 (parts by weight)

Table 2 Contents of each component in the reproducible high-temperature-resistant damping thermoplastic silicone rubber material of Examples 9-16 (parts by weight)

Comparative example 1

This comparative example provides a HDPE material, the difference between the formula and Example 3 is that no hyperbranched polyacrylate oligomer is added.

Comparative example 2

This comparative example provides a HDPE material, the difference between the formulation and Example 3 is that no PB is added.

Comparative example 3

This comparative example provides a HDPE material, the formula is different from Example 3 in that the 1# hyperbranched polyacrylate oligomer is replaced by 6# hyperbranched polyacrylate oligomer with a smaller molecular weight.

Comparative example 4

This comparative example provides a HDPE material. The difference between the formulation and Example 3 is that the 1# hyperbranched polyacrylate oligomer is replaced by the 7# hyperbranched polyacrylate oligomer with a larger molecular weight.

Comparative example 5

This comparative example provides a HDPE material, the difference of the formula from Example 3 is that HDPE-g-MAH is replaced by polar substance EVOH.

Performance Testing

The performance of the HDPE material prepared by above-mentioned embodiment and comparative example is tested, and concrete test item and method are as follows:

1. Resistance to environmental stress cracking: The HDPE materials prepared in the above examples and comparative examples were injection molded into plastic bottles, then filled with propane gas (which can be used as a representative of non-polar organic small molecule gases) to a pressure of 5 MPa, and placed at 70°C Under the conditions, observe the time for cracks to appear;

2. Barrier properties: The HDPE materials prepared in the above examples and comparative examples were injection-molded into plastic bottles, then filled with propane gas, sealed and weighed, and placed at room temperature (25-30° C.) for 30 days, weighed the residual propane Then calculate the transmission rate of propane gas in the plastic bottle, and use the "propane gas transmission rate" to characterize the barrier performance of the material;

3. Low temperature resistance performance: The low temperature resistance performance of the material is characterized by the notched Izod impact strength at -40°C. The HDPE material prepared in the above examples and comparative examples is injection molded into impact splines, and then according to "ISO180-2000" For testing, the gap type is A-type gap.

The test results are detailed in Table 3.

Table 3 performance test results

It can be seen from Table 3:

The HDPE material prepared in each embodiment of the present invention has long-term environmental stress cracking resistance, high low-temperature toughness and high barrier performance at the same time. Among them, the cracking time of the material at 70°C and the internal pressure of 5MPa is above 2000h; the transmission rate of propane gas is less than 0.1%; at -40°C, the notched impact strength of the material is above 15kJ/m ² and can be as high as 16.4 kJ/m ² .

The results of Example 3 and Examples 6-8 show that conventional commercially available HDPE resins, PB and HDPE-g-MAH can all be used in the present invention, and the prepared materials all have good environmental stress cracking resistance, low temperature toughness High and high barrier properties.

The result of embodiment 3, embodiment 9～12, comparative example 3,4 shows, for hyperbranched polyacrylate oligomer, molecular weight is too low (comparative example 3), can't promote the environmental stress cracking resistance performance of material; High (comparative example 4), the viscosity of the hyperbranched polyacrylate oligomer is too high, the compatibility with HDPE is poor, and it is easier to crack during long-term use, and the environmental stress cracking resistance and low temperature toughness of the material are significant decline. Only hyperbranched polyacrylate oligomers with appropriate molecular weight can improve the environmental stress cracking resistance of materials.

The results of Example 3 and Examples 13 to 16 show that conventional commercially available POEs can be used in the present invention, and the comparison of Example 3 and Example 13 shows that within a certain range, the melt flow rate in POE has a significant impact on the prepared The influence of the performance of the material is small, when neglecting the influence of the POE melt flow rate on the performance, the results of Example 3 and Examples 13 to 15 show that the length of the chain segment of the copolymer copolymerized with ethylene in POE Can improve its compatibility with HDPE to a certain extent, and then improve the low temperature resistance performance of material, especially select carbon 8 class POE (such as the ethylene-octene copolymer elastomer that embodiment 3 and 13 select for use), the prepared The material has the best low temperature resistance.

The results of Comparative Example 1, 2 and Comparative Example 5 show that there is a synergistic effect between hyperbranched polyacrylate oligomer, PB, and HDPE-g-MAH.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. Protection scope, within the spirit and principles of the present invention, any modification, equivalent replacement, improvement, etc., shall be included in the protection scope of the present invention.

Claims (10)

1. A high-barrier, low-temperature-resistant, and environmental-stress-crack-resistant HDPE material is characterized in that it includes components calculated according to the following parts by weight:

   

   Wherein, the number average molecular weight of the hyperbranched polyacrylate oligomer is 1000-9000.
2. The HDPE material with high barrier, low temperature resistance and environmental stress cracking resistance according to claim 1, characterized in that the melt flow rate of the HDPE under the conditions of 190°C and 2.16kg is 5-10g/10min.
3. The HDPE material with high barrier, low temperature resistance and environmental stress cracking resistance according to claim 1, characterized in that the number average molecular weight of the hyperbranched polyacrylate oligomer is 4500-8000.
4. The HDPE material with high barrier, low temperature resistance and environmental stress cracking resistance according to claim 3, characterized in that the number average molecular weight of the hyperbranched polyacrylate oligomer is 5500-6000.
5. According to the HDPE material with high barrier, low temperature resistance and environmental stress cracking resistance according to claim 1, it is characterized in that the POE is an ethylene-propylene copolymer elastomer, an ethylene-butylene copolymer elastomer or an ethylene-octene copolymer elastomer one or a combination of several.
6. The HDPE material with high barrier, low temperature resistance and environmental stress cracking resistance according to claim 5, wherein the POE is an ethylene-octene copolymerized elastomer.
7. The high-barrier, low-temperature-resistant, and environmental-stress-cracking-resistant HDPE material according to claim 1 or 5, wherein the melt flow rate of the POE at 190°C and 2.16kg is 0.5-3g/10min.
8. According to the HDPE material with high barrier, low temperature resistance and environmental stress cracking resistance according to claim 1, it is characterized in that the other additives are antioxidants and/or lubricants.
9. The preparation method of HDPE material with high barrier, low temperature resistance and environmental stress cracking resistance according to any one of claims 1 to 8, characterized in that it comprises the following steps:

   After mixing HDPE, hyperbranched polyacrylate oligomer, PB, HDPE-g-MAH, POE and other additives uniformly, it is obtained by melting and extruding under the condition of 170-210°C.
10. The application of the high-barrier, low-temperature-resistant, and environmental-stress-cracking-resistant HDPE material described in any one of claims 1 to 8 in the field of gas storage and transportation.