A method for determining the content of polyethylene n-hexane extract

Abstract

This invention discloses a method for determining the content of hexane extract in polyethylene, belonging to the field of analytical testing. The method comprises the following steps: Step 1: Wrapping polyethylene material with filter paper; Step 2: Placing the sample in a flask containing hexane and extracting it in a water bath; Step 3: Drying in an oven; Step 4: Weighing the total weight of the dried sample and filter paper; Step 5: Calculating the hexane extract content of the sample. This method solves the problems of insufficient applicability to various forms of polyethylene, unstable extraction efficiency, cumbersome operation, large testing errors, and low testing efficiency in existing standard methods for testing the content of hexane extract. By optimizing the sample preparation, extraction, and filtration processes, it achieves efficient and accurate determination of hexane extract in polyethylene powder, granules, and films of different forms.

Description

Technical Field

[0001] This invention relates to the field of analytical testing, and specifically to a method for determining the content of polyethylene n-hexane extract. Background Technology

[0002] Polyethylene, a thermoplastic material widely used in food packaging and medical devices, has attracted much attention for its safety. Low molecular weight components that can be dissolved by hexane, including polyethylene wax, residual catalysts, and processing aids, may migrate into the contact material, posing health risks and affecting material performance. Therefore, it is necessary to accurately determine their content to meet requirements.

[0003] Currently, the main method used in China is the GB / T 5009.58-2003 standard method, which involves dissolving hexane extract in polyethylene granules using hexane. This requires filtration, washing, and a concentrator to recover the hexane before drying to calculate the hexane extract content. This method is not applicable to various forms of polyethylene and suffers from problems such as unstable extraction efficiency, cumbersome operation, large testing errors, and the inability to reuse recovered hexane. Therefore, finding a simpler, more efficient, and environmentally friendly method to measure the hexane extract content in polyethylene is a problem that needs to be solved.

[0004] To address these shortcomings, this invention proposes an improved testing method that optimizes sample preparation and eliminates the filtration process, enabling efficient and accurate determination of n-hexane extracts in various forms of samples, such as polyethylene powder, granules, and films. Furthermore, it can simultaneously determine the n-hexane content of multiple samples, thereby reducing n-hexane waste and minimizing environmental pollution.

[0005] Therefore, our company has proposed a research method for determining the content of polyethylene n-hexane extract. Summary of the Invention

[0006] Purpose of the invention: A primary objective of this invention is to provide a novel testing method that can test various forms of polyethylene hexane extract, simultaneously test multiple samples, and features simple post-processing and is environmentally friendly.

[0007] To achieve the above objectives, the present invention employs the following technical solution: The weight loss of the polyethylene material after extraction with n-hexane is measured, i.e., the amount of n-hexane extract. Using this method to extract the n-hexane extract after tableting granular products allows for more accurate determination of the n-hexane extract amount. For powders and films, this method can be used without tableting. Dividing this by the original weight of the polyethylene material yields the polyethylene n-hexane extract content.

[0008] The specific technical solution of this invention is as follows:

[0009] A method for determining the content of polyethylene n-hexane extract, characterized by comprising the following steps:

[0010] Step 1: Obtain polyethylene raw materials;

[0011] Step 2: Weigh the dried filter paper to constant weight as m1, wrap it with polyethylene material and weigh the total weight m2, then use paper clips to fix it.

[0012] Step 3: Place the packaged sample into a flask containing n-hexane and extract it in a water bath;

[0013] Step 4: After extraction, remove the sample and dry it in an oven;

[0014] Step 5: Weigh the total weight (m3) of the dried sample and filter paper;

[0015] Step 6: The content of the n-hexane extract in the sample is: X = (m2-m3) / (m2-m1) × 100%.

[0016] In step one, when the polyethylene raw material is in granular form, it needs to be sheeted. The sheeting temperature is 190-240℃, and the sheet thickness is... After compression, the tablets are cut into rectangles with sides of 1-5cm.

[0017] Preferably, in step one, if the polyethylene raw material is in the form of a film, it needs to be cut into fragments with a side length of 1-5mm.

[0018] Preferably, the MFR of the polyethylene raw material in step one is 0.01-50 g / 10 min.

[0019] Preferably, in step three, the amount of n-hexane used is 100-300 mL.

[0020] Preferably, in step three, the water bath temperature is 75-90℃ and the water bath extraction time is 2-8 hours.

[0021] Preferably, in step four, the oven temperature is 60-100℃ and the oven drying time is 2-12 hours.

[0022] The present invention has the following beneficial effects:

[0023] Low molecular weight components in polyethylene that can be dissolved by hexane, including polyethylene wax, residual catalysts, and processing aids, may migrate into contact materials, posing health risks and affecting material properties. Therefore, accurate determination of their content is necessary to meet requirements. The GB / T 5009.58-2003 standard uses a method to remove hexane from polyethylene hexane extract to obtain the hexane extract mass. However, filtration during this process easily leads to extract loss and can only determine the hexane extract content in granular polyethylene products. This invention proposes an improved testing method that optimizes sample preparation and eliminates the filtration step, achieving efficient and accurate determination of hexane extracts in various forms of polyethylene samples, including powder, granules, and films.

[0024] The testing method in this invention is simple and efficient, suitable for operation in different laboratories, and has good economic benefits. Attached Figure Description

[0025] Figure 1 This is a flowchart of the method of the present invention;

[0026] Figure 2 This is the flowchart for the GB / T 5009.58-2003 method. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0028] A method for determining the content of polyethylene n-hexane extract, characterized by comprising the following steps:

[0029] Step 1: Take polyethylene raw material, the MFR of polyethylene raw material is 0.01-50g / 10min;

[0030] Step 2: Weigh the dried filter paper to constant weight as m1, wrap it with polyethylene material and weigh the total weight m2, then use paper clips to fix it.

[0031] Step 3: Place the packaged sample into a flask containing n-hexane (100-300 mL). Extract the sample in a water bath at 75-90°C for 2-8 hours.

[0032] Step 4: After extraction, remove the sample and dry it in an oven at 60-100℃ for 2-12 hours.

[0033] Step 5: Weigh the total weight (m3) of the dried sample and filter paper;

[0034] Step 6: The content of the n-hexane extract in the sample is: X = (m2-m3) / (m2-m1) × 100%.

[0035] In step one, if the polyethylene raw material is in granular form, it needs to be sheeted. The sheeting temperature is 190-240℃, and the sheet thickness is... After compression, the tablets are cut into rectangles with sides of 1-5cm.

[0036] In step one, if the polyethylene raw material is in the form of a film, it needs to be cut into fragments with a side length of 1-5mm.

[0037] Example 1

[0038] Example 1 uses polyethylene granules, Satellite FS7000, purchased from... The granules are pressed into sheets at 180°C using a tablet press, with a sheet thickness of 0.01 mm, and cut into 1 cm * 1 cm rectangles. The constant weight of dried filter paper is measured, m1 = 0.5624 g. The weight of the filter paper and the cut sample is measured, m2 = 2.1909 g. After wrapping, they are secured with paper clips.

[0039] The samples were placed together with other samples in a flask containing n-hexane and extracted in a water bath at 80°C for 2 hours.

[0040] Remove the sample at 80℃ and dry it in an oven at 80℃ for 4 hours.

[0041] The total weight of the dried sample and filter paper is m3 = 2.1566g.

[0042] The content of n-hexane extract in the sample is:

[0043] X=(m2-m3) / (m2-m1)×100%=(2.1909-2.1566) / (2.1909-0.5624)×100%=2.11%

[0044] The method of this invention can quickly determine the content of n-hexane extract in granular polyethylene by simply performing pressing, filter paper wrapping, extraction and drying operations. In Example 1, the content of n-hexane extract in the polyethylene granule satellite FS7000 was 2.11%.

[0045] Example 2

[0046] Example 2 follows the same method as Example 1, except that Example 3 uses Iranian Black 7000 polyethylene granules, purchased from Mehr Petrochemical Company in Iran, with weighed masses of m1=0.6315g, m2=2.2284g, and m3=2.1760g.

[0047] The content of n-hexane extract in the sample is:

[0048] X=(m2-m3) / (m2-m1)×100%=(2.2284-2.1760) / (2.2284-0.6315)×100%=3.28%

[0049] The method of this invention can quickly determine the content of n-hexane extract in granular polyethylene by simply performing pressing, filter paper wrapping, extraction and drying operations. In Example 2, the content of n-hexane extract in the polyethylene granules Iranian Black 7000 was 3.28%.

[0050] Example 3

[0051] Example 3 uses the same method as Example 1, except that it uses Lotte 2600F polyethylene granules, purchased from Lotte Chemical Corporation in South Korea. The weighed masses are m1=0.6313g, m2=2.0069g, and m3=1.9735g, respectively.

[0052] The content of n-hexane extract in the sample is:

[0053] X=(m2-m3) / (m2-m1)×100%=(2.0069-1.9735) / (2.2284-0.6313)×100%=2.43%

[0054] The method of this invention can quickly determine the content of n-hexane extract in granular polyethylene by simply performing pressing, filter paper wrapping, extraction and drying operations. In Example 3, the content of n-hexane extract in the polyethylene granules Lotte 2600F was 2.43%.

[0055] Example 4

[0056] Example 4 uses the same method as Example 1, except that it uses polyethylene granules, Zhenhai 2911H, purchased from Zhenhai Refining & Chemical Branch of China Petroleum & Chemical Corporation. The weighed masses are m1=0.6331g, m2=2.2762g, and m3=2.2410g.

[0057] The content of n-hexane extract in the sample is:

[0058] X=(m2-m3) / (m2-m1)×100%=(2.2762-2.2410) / (2.2762-0.6331)×100%=2.14%

[0059] The method of this invention can quickly determine the content of n-hexane extract in granular polyethylene by simply pressing, wrapping with filter paper, extracting and drying. In Example 4, the content of n-hexane extract in the polyethylene granules Zhenhai 2911H was 2.14%.

[0060] Example 5

[0061] Example 5 used polyethylene powder Satellite FS7000, produced by Lianyungang Petrochemical Co., Ltd., with a particle size of 0.1 mm. The dried filter paper was weighed to a constant weight (m4 = 0.6417 g), and the filter paper and the cut sample were weighed (m5 = 2.5459 g). The mixture was wrapped and secured with paper clips. It was placed in a flask containing n-hexane and extracted in an 80°C water bath for 2 hours.

[0062] Remove the sample at 80℃ and dry it in an oven at 80℃ for 4 hours.

[0063] The total weight of the dried sample and filter paper is m6 = 2.4986 g.

[0064] The content of n-hexane extract in the sample is:

[0065] X=(m5-m6) / (m5-m4)×100%=(2.5459-2.4986) / (2.5459-0.6417)×100%=2.48%

[0066] The method of this invention can quickly determine the content of n-hexane extract in polyethylene powder by simply wrapping it in filter paper, extracting it, and drying it. In Example 5, the content of n-hexane extract in polyethylene powder satellite FS7000 was 2.48%.

[0067] Example 6

[0068] Example 6 uses the same method as Example 5, except that Example 6 uses polyethylene powder, Iranian Black 7000, purchased from Mehr Petrochemical Company in Iran, with a particle size of 0.5 mm. The weighed masses are as follows:

[0069] m4=0.6203g,m5=2.4275g,m6=2.3728g

[0070] The content of n-hexane extract in the sample is:

[0071] X=(m5-m6) / (m5-m4)×100%=(2.4275-2.3728) / (2.4275-0.6203)×100%=3.03%

[0072] The method of this invention can quickly determine the content of n-hexane extract in polyethylene powder by simply wrapping it in filter paper, extracting it, and drying it. In Example 6, the content of n-hexane extract in the polyethylene powder Iranian Black 7000 was 3.03%.

[0073] Example 7

[0074] Example 7 follows the same method as Example 5, except that Example 7 uses Lotte 2600F polyethylene powder, purchased from Lotte Chemical Corporation in South Korea, with a particle size of 1 mm. The weighed masses are m4=0.6102g, m5=2.4784g, and m6=2.4447g.

[0075] The content of n-hexane extract in the sample is:

[0076] X=(m5-m6) / (m5-m4)×100%=(2.4784-2.4447) / (2.4784-0.6102)×100%=1.80%

[0077] The method of this invention can quickly determine the content of n-hexane extract in polyethylene powder by simply wrapping it in filter paper, extracting it, and drying it. In Example 7, the content of n-hexane extract in the polyethylene powder Lotte 2600F was 1.80%.

[0078] Example 8

[0079] Example 8 uses the same method as Example 5, the difference being that Example 8 uses polyethylene powder Zhenhai 2911H, purchased from Zhenhai Refining & Chemical Branch of China Petroleum & Chemical Corporation, with a particle size of 2mm. The weighed masses are m4=0.6256g, m5=2.2607g, and m6=2.2336g.

[0080] The content of n-hexane extract in the sample is:

[0081] X=(m5-m6) / (m5-m4)×100%=(2.2607-2.2336) / (2.2607-0.6256)×100%=1.66%

[0082] The method of this invention can quickly determine the content of n-hexane extract in polyethylene powder by simply wrapping it in filter paper, extracting it, and drying it. In Example 8, the content of n-hexane extract in polyethylene powder Zhenhai 2911H was 1.66%.

[0083] Example 9

[0084] Example 9 used a polyethylene membrane material, Satellite FS7000, produced by Lianyungang Petrochemical Co., Ltd., with a thickness of 0.025 mm. The membrane material was cut into pieces, with each fragment having a side length of 1 mm. The dried filter paper was weighed to a constant weight (m7 = 0.6194 g), and the filter paper and the cut sample were weighed together (m8 = 2.5409 g). These were wrapped and secured with paper clips. The mixture was placed in a flask containing n-hexane and extracted in an 80°C water bath for 2 hours.

[0085] Remove the sample at 80℃ and dry it in an oven at 80℃ for 4 hours.

[0086] The total weight of the dried sample and filter paper is m9 = 2.4870 g.

[0087] The content of n-hexane extract in the sample is:

[0088] X=(m8-m9) / (m8-m7)×100%=(2.5409-2.4870) / (2.5409-0.6194)×100%=2.81%

[0089] The method of this invention can quickly determine the content of n-hexane extract in a sample by simply cutting the polyethylene membrane material into pieces, wrapping it with filter paper, extracting and drying it. In Example 9, the content of n-hexane extract in the polyethylene membrane material Satellite FS7000 was 2.81%.

[0090] Example 10

[0091] Example 10 follows the same method as Example 9, except that Example 10 uses Iranian Black Letter 7000 polyethylene film material, purchased from Mehr Petrochemical Company in Iran, with a thickness of 0.025 mm. The film material is cut into pieces, with each fragment having a side length of 2 mm. The weighed masses are m7=0.6078g, m8=2.0755g, and m9=2.0309g.

[0092] The content of n-hexane extract in the sample is:

[0093] X=(m8-m9) / (m8-m7)×100%=(2.0755-2.0309) / (2.0755-0.6078)×100%=3.04%

[0094] The method of this invention can quickly determine the content of n-hexane extract in polyethylene membrane material by simply cutting the membrane material into pieces, wrapping it with filter paper, extracting and drying it. In Example 10, the content of n-hexane extract in the polyethylene membrane material Iran Black 7000 was 3.04%.

[0095] Example 11

[0096] Example 11 uses the same method as Example 9, except that Example 11 uses Lotte 2600 polyethylene film material, purchased from Lotte Chemical Corporation in South Korea, with a thickness of 1 mm. The film material is cut into pieces, with each fragment having a side length of 3 mm. The weighed masses are m7=0.6348g, m8=2.5017g, and m9=2.4639g.

[0097] The content of n-hexane extract in the sample is:

[0098] X=(m8-m9) / (m8-m7)×100%=(2.5017-2.4639) / (2.5017-0.6348)×100%=2.02%

[0099] The method of this invention can quickly determine the content of n-hexane extract in a sample by simply cutting the polyethylene film into pieces, wrapping it with filter paper, extracting and drying it. In Example 11, the content of n-hexane extract in the polyethylene film Lotte 2600 was 2.02%.

[0100] Example 12

[0101] Example 12 follows the same method as Example 9, except that Example 12 uses polyethylene film material Zhenhai 2911H, purchased from Zhenhai Refining & Chemical Branch of China Petroleum & Chemical Corporation, with a thickness of 2mm. The film material is cut into pieces, with each fragment having a side length of 5mm. The weighed masses are m7=0.5900g, m8=2.3852g, and m9=2.3607g.

[0102] The content of n-hexane extract in the sample is:

[0103] X=(m8-m9) / (m8-m7)×100%=(2.3852-2.3607) / (2.3852-0.5900)×100%=1.36%

[0104] The method of this invention can quickly determine the content of n-hexane extract in polyethylene membrane material by simply cutting the membrane material into pieces, wrapping it with filter paper, extracting and drying it. In Example 12, the content of n-hexane extract in polyethylene membrane material Zhenhai 2911H was 1.36%.

[0105] Comparative Example 1

[0106] Comparative Example 1 used the same batch of polyethylene granules, Satellite FS7000, produced by Lianyungang Petrochemical Co., Ltd., as in Example 1. A solid sample (m10 = 1.6042 g) was weighed and placed in a 250 ml flask. 100 ml of n-hexane was added, and the flask was refluxed in an 80°C water bath for 2 hours. Immediately afterwards, the sample was filtered through qualitative filter paper. The filter and sample were then washed with a small amount of n-hexane. The washings and filtrate were placed together in a concentrator bottle (concentrator bottle mass m11 = 167.7426 g) to concentrate and recover the n-hexane. The residue was dried in a 100°C oven for 2 hours and cooled for 30 minutes. The residue, along with the concentrate bottle, was weighed (m12 = 167.7756 g).

[0107] The hexane extract and its content are calculated as follows:

[0108] X=(m12-m11) / m10×100%=(167.7756-167.7426) / 1.6042×100%=2.06%

[0109] The same batch of polyethylene granules, Satellite FS7000, was tested using the standard method of GB / T 5009.58-2003. After hexane extraction, the filter and sample were washed. This step easily resulted in a loss of extract amount. As can be seen from the results of Comparative Example 1 and Example 1, the hexane content of 2.06% obtained by the standard method was less than the 2.11% obtained by the method of this invention.

[0110] Comparative Example 2

[0111] Comparative Example 2 used the same method as Comparative Example 1, except that it used the same batch of polyethylene granules as Example 2, Iranian Black 7000, purchased from Mehr Petrochemical Company in Iran, with m12 = 167.7948 g, m11 = 167.7431 g, and m10 = 1.6123 g.

[0112] The hexane extract and its content are calculated as follows:

[0113] X=(m12-m11) / m10×100%=(167.7948-167.7431) / 1.6123×100%=3.21%

[0114] The same batch of polyethylene granules, Iranian Black 7000, was tested using the standard method of GB / T 5009.58-2003. After hexane extraction, the filter and sample were washed. This step easily resulted in a loss of extract amount. As can be seen from the results of Comparative Example 2 and Example 2, the hexane content of 3.21% obtained by the standard method is less than the 3.28% obtained by the method of this invention.

[0115] Through examples and comparative examples The content of the polyethylene n-hexane extract was determined, and the results are shown in the table below:

[0116] Table 1. Results of determination of n-hexane extract content in polyethylene granules

[0117]

[0118] Table 2. Results of determination of n-hexane extract content in polyethylene powder

[0119]

[0120] Table 3. Results of determination of n-hexane extract content in polyethylene film material

[0121]

[0122] The above results indicate that:

[0123] Examples 1 and 2 and Comparative Examples 1 and 2 show that the method of the present invention yields a higher content of polyethylene n-hexane extract, indicating that the method is more accurate and simpler to implement, with fewer experimental steps, thus avoiding the loss of n-hexane extract due to redundant processes.

[0124] The method for determining the content of n-hexane extract in polyethylene described in this invention modifies the weighing target in existing methods for extracting n-hexane from polyethylene, equating the amount of n-hexane extract to the weight loss of polyethylene during the n-hexane extraction process. This reduces the loss during the drying process of the n-hexane extract obtained from the filtrate and washings in the GB / T 5009.58-2003 standard method. Furthermore, it expands the range of polyethylene material morphologies that can be used with this method, improving the accuracy of the results. The tableting process for particulate samples is simple to operate and suitable for widespread application.

[0125] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for determining the content of polyethylene n-hexane extract, characterized in that, Includes the following steps: Step 1: Obtain polyethylene raw materials; Step 2: Weigh the dried filter paper to constant weight as m1, wrap it with polyethylene material and weigh the total weight m2, then use paper clips to fix it. Step 3: Place the packaged sample into a flask containing n-hexane and extract it in a water bath; Step 4: After extraction, remove the sample and dry it in an oven; Step 5: Weigh the total weight (m3) of the dried sample and filter paper; Step 6: The content of the n-hexane extract in the sample is: X = (m2-m3) / (m2-m1) × 100%.

2. The method for determining the content of polyethylene n-hexane extract according to claim 1, characterized in that: In step one, when the polyethylene raw material is in granular form, it needs to be sheeted. The sheeting temperature is 190-240℃, and the sheet thickness is... After compression, the tablets are cut into rectangles with sides of 1-5cm.

3. The determination method according to claim 1, characterized in that: In step one, when the polyethylene raw material is in the form of a film, it needs to be cut into fragments with a side length of 1-5mm.

4. The method for determining the content of polyethylene n-hexane extract according to claim 1, characterized in that: In step one, the MFR of the polyethylene raw material is 0.01-50 g / 10 min.

5. The method for determining the content of polyethylene n-hexane extract according to claim 1, characterized in that: In step three, the amount of n-hexane used is 100-300 mL.

6. The method for determining the content of polyethylene n-hexane extract according to claim 1, characterized in that: In step three, the water bath temperature is 75-90℃, and the water bath extraction time is 2-8 hours.

7. The method for determining the content of polyethylene n-hexane extract according to claim 1, characterized in that: In step four, the oven temperature is 60-100℃ and the oven drying time is 2-12 hours.

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