Medium density polyethylene sheath material and preparation method thereof

Abstract

The invention discloses a medium-density polyethylene sheath material and a preparation method thereof, wherein the preparation method of the medium-density polyethylene sheath material comprises the following steps: 1) by weight percentage, 25-31wt% of HDPE resin, 40-46wt% of EPPE resin, 16-20wt% of MDPE resin, 5.40-6.20wt% of carbon black masterbatch, 2.5-3.5wt% of prefabricated modified masterbatch containing high-gloss barium sulfate, 0.35-0.45wt% of antioxidant and 0.35-0.45wt% of lubricant are put into a mixer for premixing to obtain a uniform premix; and 2) the premix obtained in step 1) is extruded and granulated at 180-200° C. by a twin-screw extruder, and cooled to obtain the medium-density polyethylene sheath material. Compared with the prior art, in the preparation method of the medium density polyethylene sheath material of the present invention, the prefabricated modified masterbatch contains high-gloss barium sulfate, which can improve the melt strength of the resin, improve the smoothness and fineness of the extrusion, and improve the dispersion effect of the rheological agent in the masterbatch. EPPE resin is a special LLDPE resin containing long chain branches, with low crystallinity and high melt strength, and has the performance of low temperature processing and shear resistance.

Description

Technical Field

[0001] The invention belongs to the field of polyethylene sheathing materials, and more specifically, relates to a medium-density polyethylene sheathing material and a preparation method thereof. Background Art

[0002] Due to design and usage requirements, the core of some special optical cables contains fusible components such as PP filling rope or HDPE insulation layer. Due to usage requirements (such as easy cable stripping), the cable core can only be simply coated before sheathing.

[0003] In order to prevent the fusible components from melting and sticking when forming the cable sheath, the processing temperature of the final cable sheathing process needs to be reduced as much as possible. At present, the cable extruders in the optical cable industry are generally 90 machines. According to research and development, the maximum temperature setting of the extruder for optical cables containing fusible components must be controlled at 170-180℃, while the processing temperature of conventional medium-density polyethylene sheathing materials is generally 230-240℃, which is about 60℃ higher than the maximum temperature of the extruder and cannot meet the process requirements.

[0004] In view of this, it is indeed necessary to provide a medium-density polyethylene sheath material with an ideal extrusion temperature and a preparation method thereof. Summary of the invention

[0005] The object of the present invention is to overcome at least one defect in the prior art and provide a medium-density polyethylene sheath material with an ideal extrusion temperature and a preparation method thereof.

[0006] In order to achieve the above object, the present invention provides a method for preparing a medium-density polyethylene sheath material, which comprises the following steps:

[0007] 1) By weight percentage, 25-31wt% HDPE resin, 40-46wt% EPPE resin, 16-20wt% MDPE resin, 5.40-6.2wt% carbon black masterbatch, 2.5-3.5wt% prefabricated modified masterbatch containing high-gloss barium sulfate, 0.35-0.45wt% antioxidant and 0.35-0.45wt% lubricant are put into a mixer for premixing to obtain a uniform premix; and

[0008] 2) The premix obtained in step 1) is extruded and granulated at 180-200° C. by a twin-screw extruder, and then cooled to obtain a medium-density polyethylene sheath material.

[0009] According to one embodiment of the method for preparing a medium density polyethylene sheath material of the present invention, in step 1), the lubricant is polyethylene wax.

[0010] According to one embodiment of the method for preparing a medium density polyethylene sheath material of the present invention, in step 1), the antioxidant is a composite antioxidant AT-225 (a mixture of antioxidants AT-10 and AT-168).

[0011] According to one embodiment of the method for preparing a medium density polyethylene sheath material of the present invention, in step 1), the carbon black masterbatch is a 45% carbon black masterbatch (carbon black content 45%).

[0012] According to one embodiment of the method for preparing a medium density polyethylene sheath material of the present invention, in step 1), the density of the HDPE resin is 0.945-0.949 g / cm 3 The melt flow rate is 0.6-0.8 g / 10 min; the density of the EPPE resin is 0.916-0.920 g / cm 3 , the melt flow rate is 1.8-2.2 g / 10 min; the density of the MDPE resin is 0.928-0.932 g / cm 3 , the melt flow rate is 0.2-0.3g / 10min.

[0013] According to one embodiment of the method for preparing the medium density polyethylene sheath material of the present invention, in step 1), the premixing is carried out in a vertical mixer for 3-5 minutes.

[0014] According to one embodiment of the method for preparing a medium-density polyethylene sheath material of the present invention, the prefabricated modified masterbatch containing high-gloss barium sulfate is prepared according to the following steps:

[0015] 11) In terms of weight percentage, 54-58wt% EPPE, 2.8-3.2wt% PPA, 38-42wt% high-gloss barium sulfate, 0.4-0.6wt% lubricant and 0.4-0.6wt% antioxidant are put into an internal mixer and premixed uniformly;

[0016] 12) mixing the uniformly premixed materials in step 11) in an internal mixer for not less than 12 minutes at a melt temperature of 150-155° C. to obtain a well-plasticized mass; and

[0017] 13) The mass after the internal mixing in step 12) is fed into a twin-screw extruder, extruded by the twin-screw extruder at 120-140° C., granulated by a single-screw granulator at 130-150° C., air-cooled and vibrated to obtain a modified masterbatch.

[0018] According to one embodiment of the method for preparing a medium density polyethylene sheath material of the present invention, in step 11), the lubricant is polyethylene wax.

[0019] According to one embodiment of the method for preparing a medium density polyethylene sheath material of the present invention, in step 11), the antioxidant is a composite antioxidant AT-225.

[0020] In order to achieve the above-mentioned object of the invention, the present invention further provides a medium-density polyethylene sheathing material, which is prepared according to the preparation method of the medium-density polyethylene sheathing material of the present invention.

[0021] Compared with the prior art, the medium-density polyethylene sheath material and the preparation method thereof of the present invention have the following advantages: the prefabricated modified masterbatch contains high-gloss barium sulfate, which can improve the melt strength of the resin, improve the smoothness and fineness of the extrusion, and improve the dispersion effect of the rheological agent in the masterbatch; the EPPE resin is a special LLDPE resin containing long-chain branches, which has low crystallinity and high melt strength, and also has the performance of low-temperature processing and shear resistance. DETAILED DESCRIPTION

[0022] In order to make the invention purpose, technical solution and technical effect of the present invention clearer, the present invention is further described in detail below in conjunction with specific implementation methods. It should be understood that the specific implementation methods described in this specification are only for explaining the present invention, not for limiting the present invention.

[0023] The present invention provides a method for preparing a medium-density polyethylene sheath material, which comprises the following steps:

[0024] 1) by weight percentage, 25-31wt% HDPE resin, 40-46wt% EPPE resin, 16-20wt% MDPE resin, 5.40-6.2wt% carbon black masterbatch, 2.5-3.5wt% prefabricated modified masterbatch containing high-gloss barium sulfate, 0.35-0.45wt% antioxidant and 0.35-0.45wt% lubricant are put into a mixer for premixing to obtain a uniform premix; and

[0025] 2) The premix obtained in step 1) is extruded and granulated at 180-200° C. by a twin-screw extruder, and then cooled to obtain a medium-density polyethylene sheath material.

[0026] According to one embodiment of the method for preparing the medium density polyethylene sheath material of the present invention, in step 1), the lubricant is polyethylene wax, the antioxidant is composite antioxidant AT-225, and the carbon black masterbatch is 45% carbon black masterbatch.

[0027] According to one embodiment of the method for preparing a medium density polyethylene sheath material of the present invention, in step 1), the density of the HDPE resin is 0.945-0.949 g / cm 3 , melt flow rate is 0.6-0.8g / 10min; density of EPPE resin is 0.916-0.920g / cm3 , melt flow rate is 1.8-2.2g / 10min; density of MDPE resin is 0.928-0.932g / cm 3 , the melt flow rate is 0.2-0.3g / 10min.

[0028] According to one embodiment of the method for preparing the medium density polyethylene sheath material of the present invention, premixing is performed in a vertical mixer, and the premixing time is 3-5 minutes.

[0029] According to one embodiment of the method for preparing a medium density polyethylene sheath material of the present invention, a prefabricated modified masterbatch containing high-gloss barium sulfate is prepared according to the following steps:

[0030] In terms of weight percentage, 54-58wt% EPPE, 2.8-3.2wt% PPA, 38-42wt% high-gloss barium sulfate, 0.4-0.6wt% lubricant and 0.4-0.6wt% antioxidant are put into an internal mixer and premixed uniformly;

[0031] 12) mixing the uniformly premixed materials in step 11) in an internal mixer for not less than 12 minutes at a melt temperature of 150-155° C. to obtain a well-plasticized mass; and

[0032] 13) The mass after the internal mixing in step 12) is fed into a twin-screw extruder, extruded by the twin-screw extruder at 120-140° C., granulated by a single-screw granulator at 130-150° C., air-cooled and vibrated to obtain a modified masterbatch.

[0033] According to one embodiment of the method for preparing a medium density polyethylene sheath material of the present invention, in step 11), the lubricant is polyethylene wax, and the antioxidant is composite antioxidant AT-225.

[0034] The preparation method of the high density polyethylene sheath material of the present invention is described in detail below in combination with examples and performance tests.

[0035] Example 1 Preparation of prefabricated modified masterbatch containing high-gloss barium sulfate

[0036] Prepare the pre-made compound masterbatch as follows:

[0037] 11) In terms of weight percentage, 54wt% EPPE (Sumitomo CB1001), 3.0wt% PPA (Shanghai Luju 2200B), 42wt% high-gloss barium sulfate, 0.5wt% lubricant polyethylene wax and 0.5wt% composite antioxidant AT-225 were put into an internal mixer and premixed uniformly;

[0038] 12) kneading the uniformly premixed materials in step 11) at 150-155° C. for not less than 12 minutes to obtain a well-plasticized mass; and

[0039] 13) The mass after the internal mixing in step 12) is fed into a twin-screw extruder through a forced feeder, extruded by the twin-screw extruder at 120-140° C., granulated by a single-screw granulator at 130-150° C., air-cooled and vibrated to obtain a modified masterbatch.

[0040] Example 2-3 Preparation of prefabricated modified masterbatch containing high-gloss barium sulfate

[0041] The preparation methods of Example 2-3 are basically the same as those of Example 1, except that the contents of the components are different. Please refer to Table 1 for the components and contents of Example 2-3.

[0042] Comparative Example 1 Preparation of prefabricated modified masterbatch containing high-gloss barium sulfate

[0043] The preparation methods of the comparative example and embodiment 1 are basically the same, except that the contents of the components are different. Please refer to Table 1 for the components and contents of comparative example 1.

[0044] Table 1 Components and contents of prefabricated modified masterbatch of Examples 1-3 and Comparative Example 1

[0045] Components Example 1 Example 2 Example 3 Comparative Example 1 EPPE-Sumitomo CB1001 54.0％ 56.0％ 58.0％ 62.0％ High gloss barium sulfate 42.0％ 40.0％ 38.0％ 34.0％ PPA-Shanghai Luju 2200B 3.0％ 2.8％ 3.2％ 3.0％ Polyethylene wax 0.5％ 0.6％ 0.4％ 0.5％ Antioxidant AT-225 0.5％ 0.6％ 0.4％ 0.5％

[0046] The banburying time of Examples 1-3 and Comparative Example 1 was ≥12 minutes, and the banburying temperature was 150-155°C. The prefabricated modified masterbatch of Examples 1-3 had good processing performance and dispersion effect. After the banburying temperature and time of Comparative Example 1 reached the requirements, the melt was too thin and the pan was seriously sticky. The material could not be discharged and could only be discharged after the melt was slowly cooled for about 30 minutes, which seriously affected the production efficiency.

[0047] Preparation of medium density polyethylene sheath material in Example 4

[0048] Prepare medium density polyethylene sheath material according to the following steps:

[0049] 1) by weight percentage, 25wt% HDPE resin (Dow DuPont 3364), 46wt% EPPE resin (Sumitomo CB1001), 19.4wt% MDPE resin (Borouge FB2310), 5.40wt% carbon black masterbatch (Qingdao Weidongke 45% carbon black masterbatch), 3.5wt% prefabricated modified masterbatch of Example 1, 0.35wt% antioxidant (composite antioxidant AT-225) and 0.35wt% lubricant polyethylene wax were put into a vertical mixer and premixed for 3-5 minutes to obtain a uniform premix; and

[0050] 2) The premix obtained in step 1) is extruded and granulated at 180-200° C. through a twin-screw extruder with a length-to-diameter ratio of 44:1, and the extruder temperature is: 170-180-190-200-200-200-200-190-190-190-200-200. After extrusion and plasticization, the premix is ​​cooled by water drawing, pelletized, dried, homogenized and packaged to obtain a medium-density polyethylene sheath material.

[0051] Preparation of medium density polyethylene sheath material in Example 5-6

[0052] The preparation methods of Examples 5-6 and 4 are basically the same, except that the contents of the components are different. Please refer to Table 2 for the components and contents of Examples 5-6.

[0053] Table 2 Composition and content of the medium density polyethylene sheath material in Examples 4-6

[0054] Components Example 4 Example 5 Example 6 HDPE resin-DowDuPont 3364 25.0％ 30.4％ 31.0％ EPPE resin-Sumitomo CB1001 46.0％ 40.0％ 43.5％ MDPE resin-Borouge FB1370 19.4％ 20.0％ 16.0％ 45% Carbon Black Masterbatch-Qingdao Weidongke 5.4％ 6.2％ 5.7％ Example 1 Prefabricated modified masterbatch 3.5％ 2.5％ 3.0％ Antioxidant AT-225 0.35％ 0.45％ 0.40％ Polyethylene wax 0.35％ 0.45％ 0.40％ total 100.0％ 100.0％ 100.0％

[0055] Various performance index tests

[0056] The medium density polyethylene sheath material of Example 4-6 was tested according to the requirements of GB / T15065-2009. The test results showed that all performance tests met the national standard requirements. The test results are shown in Table 3.

[0057] Table 3 Performance test results of medium density polyethylene sheath material in Examples 4-6

[0058]

[0059] Extrusion process performance test

[0060] The extrusion process performance test was carried out on the medium density polyethylene sheath material of Examples 4-6:

[0061] Extruder model: SJ90×25 (screw diameter 90mm, aspect ratio 25:1), equipment manufacturer: Wuxi Nanfang Electrical Machinery Co., Ltd., the optical cable model selected for the tube extrusion mold test machine is ordinary steel belt optical cable, the outer diameter of the optical cable is 8.0-9.0mm, the normal production speed is 50m / min, and the process comparison is used to verify the process performance difference between the medium density polyethylene sheath material of the present invention and the ordinary medium density polyethylene sheath material.

[0062] The first comparison: the medium density polyethylene sheath material in Examples 4-6 of the present invention and the existing medium density polyethylene sheath material were extruded respectively at the normal extrusion temperatures of 170-200-230-240-240-245-245-250. The results showed that under the conditions of a 90×25 extruder, a temperature of 230-250°C and a speed of 50m / min, the extrusion process performance of the medium density polyethylene sheath material in Examples 4-6 of the present invention and the existing medium density polyethylene sheath material were both very good, the extruded surface was smooth and delicate, and both met the process requirements.

[0063] The second comparison: the medium density polyethylene sheath material of Examples 4-6 of the present invention and the existing medium density polyethylene sheath material were extruded at an extrusion temperature of 160-170-180-180-170-170-170 respectively. The results showed that when the temperature of the 90×25 extruder dropped from 230-250°C to 170-180°C, the extrusion appearance of the existing medium density polyethylene sheath material decreased significantly, and severe flow lines and shark skin appeared, which could not meet the process requirements. The possible reason was that the temperature was too low, resulting in poor plasticization; the medium density polyethylene sheath material of Examples 4-6 of the present invention still had excellent extrusion performance. Appearance: the surface remains smooth and delicate. The possible reasons are: 1. Improvement of process performance by prefabricated modified masterbatch: the prefabricated modified masterbatch contains high-gloss barium sulfate, which can improve the melt strength of the resin, improve the smoothness and fineness of extrusion, and improve the dispersion effect of the rheological agent in the masterbatch; 2. The LLDPE resin used is EPPE-CB1001, which is a special LLDPE resin containing long chain branches. Compared with ordinary LLDPE resin, CB1001 has low crystallinity and high melt strength, which enables it to have low-temperature processing and shear resistance.

[0064] Combined with the above detailed description of the embodiments of the present invention, it can be seen that, compared with the prior art, the medium-density polyethylene sheath material and its preparation method of the present invention have the following advantages: the prefabricated modified masterbatch contains high-gloss barium sulfate, which can improve the melt strength of the resin, improve the smoothness and fineness of the extrusion, and improve the dispersion effect of the rheological agent in the masterbatch. EPPE resin is a special LLDPE resin containing long-chain branches, which has low crystallinity and high melt strength, and has low-temperature processing and shear resistance. The medium-density polyethylene sheath material of the present invention has many unique advantages: such as reducing equipment energy consumption, improving the structural design of optical cables, reducing the shrinkage rate of optical cables, etc., and can be widely used in various fields.

[0065] According to the above principles, the present invention can also make appropriate changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A method for preparing a medium-density polyethylene sheath material, characterized in that: The following steps are involved: 1) By weight percentage, 25-31wt% HDPE resin, 40-46wt% EPPE resin, 16-20wt% MDPE resin, 5.40-6.20wt% carbon black masterbatch, 2.5-3.5wt% prefabricated modified masterbatch containing high-gloss barium sulfate, 0.35-0.45wt% antioxidant and 0.35-0.45wt% lubricant are put into a mixer for premixing to obtain a uniform premix, wherein the prefabricated modified masterbatch containing high-gloss barium sulfate is prepared according to the following steps: 11) In terms of weight percentage, 54-58wt% EPPE, 2.8-3.2wt% PPA, 38-42wt% high-gloss barium sulfate, 0.4-0.6wt% lubricant and 0.4-0.6wt% antioxidant are put into an internal mixer and premixed uniformly; 12) mixing the uniformly premixed materials in step 11) in an internal mixer for not less than 12 minutes at a melt temperature of 150-155° C. to obtain a well-plasticized mass; and 13) feeding the mass after the internal mixing in step 12) into a twin-screw extruder, extruding at 120-140° C. by the twin-screw extruder, granulating by a single-screw granulator at 130-150° C., air-cooling and vibrating to obtain a modified masterbatch; as well as 2) The premix obtained in step 1) is extruded and granulated at 180-200° C. by a twin-screw extruder, and then cooled to obtain a medium-density polyethylene sheath material.

2. The method for preparing the medium density polyethylene sheath material according to claim 1, characterized in that: In step 1), the lubricant is polyethylene wax.

3. The method for preparing the medium density polyethylene sheath material according to claim 1, characterized in that: In step 1), the antioxidant is the composite antioxidant AT-225.

4. The method for preparing the medium density polyethylene sheath material according to claim 1, characterized in that: In step 1), the carbon black masterbatch is 45% carbon black masterbatch.

5. The method for preparing the medium density polyethylene sheath material according to claim 1, characterized in that: In step 1), the density of the HDPE resin is 0.945-0.949 g / cm 3 The melt flow rate is 0.6-0.8 g / 10 min; the density of the EPPE resin is 0.916-0.920 g / cm 3 , the melt flow rate is 1.8-2.2 g / 10 min; the density of the MDPE resin is 0.928-0.932 g / cm 3 , the melt flow rate is 0.2-0.3g / 10min.

6. The method for preparing the medium density polyethylene sheath material according to claim 1, characterized in that: In step 1), the premixing is carried out in a vertical mixer, and the premixing time is 3-5 minutes.

7. The method for preparing the medium density polyethylene sheath material according to claim 1, characterized in that: In step 11), the lubricant is polyethylene wax.

8. The method for preparing a medium density polyethylene sheath material according to claim 1, characterized in that: In step 11), the antioxidant is a composite antioxidant AT-225.

9. A medium density polyethylene sheath material, characterized in that: The medium-density polyethylene sheath material is prepared according to the preparation method of the medium-density polyethylene sheath material according to any one of claims 1 to 8.

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