A color weather-resistant 4000h high-density polyethylene sheath material and a preparation method thereof

Abstract

The application discloses a kind of color weather-resistant 4000h high-density polyethylene sheath material and preparation method thereof, belong to polyethylene sheath material field.The sheath material includes 90-95wt% base material and 5-10wt% auxiliary material according to weight percentage;Base material is composed of 40-45wt% polyethylene resin A, 30-35wt% polyethylene resin B, 20-25wt% polyethylene resin C, by "high-low-middle" melt index combination form gradient molecular weight distribution "multimodal" system, construct rigid skeleton and flexible connection, improve environmental stress cracking resistance.Auxiliary material includes POE elastomer, antioxidant masterbatch, nano TiO2, light stabilizer (UV-531 and UV-770 compound), antioxidant (AO-1010 and AO-168 compound), nucleating agent, lubricant and acid absorbent, form multistage ultraviolet system, elastomer toughening and acid catalytic inhibition synergistic effect.Preparation method includes premixing, twin-screw extrusion, cooling granulation.The sheath material of the application is weather-resistant for 4000h without carbon black shielding, with excellent mechanical properties, suitable for complex climate environments such as strong ultraviolet and high temperature.

Description

Technical Field

[0001] This invention belongs to the field of polyethylene sheathing materials, and more specifically, relates to a colored, weather-resistant 4000h high-density polyethylene sheathing material and its preparation method. Background Technology

[0002] Polyethylene sheathing materials possess excellent mechanical properties, chemical corrosion resistance, electrical insulation properties, and good processing performance, making them widely used in the outer sheath structure of optical cables, electrical cables, and communication lines. The primary function of the sheathing material is to provide mechanical protection for the internal optical fibers or conductors, while simultaneously resisting the effects of external environmental factors such as ultraviolet radiation, humid and hot environments, and chemical media, thereby ensuring the stability and reliability of communication lines during long-term outdoor use. Currently, common polyethylene sheathing materials mainly include black sheathing materials and colored sheathing materials. Black sheathing materials typically improve the material's weather resistance by adding a certain amount of carbon black to the polyethylene matrix. Carbon black not only absorbs ultraviolet radiation but also forms an effective ultraviolet shielding layer on the material surface, thus inhibiting the breakage of polyethylene molecular chains under ultraviolet light. Therefore, black polyethylene sheathing materials generally have better weather resistance and a longer outdoor service life. However, in practical engineering applications, colored polyethylene sheathing materials are often required for line identification, product differentiation, and to meet the special requirements of certain projects. For example, in communication optical cables, power cables, and underground pipeline projects, different colored sheath materials can be used to distinguish lines of different uses or specifications. Therefore, colored polyethylene sheath materials have significant engineering value in practical applications.

[0003] Because colored sheath materials typically contain little or no carbon black, their shielding ability against ultraviolet radiation is significantly lower than that of black sheath materials. Under prolonged ultraviolet radiation, polyethylene molecular chains are prone to photo-oxidation, generating free radicals and further initiating chain degradation reactions. This leads to a gradual decrease in the material's tensile strength and elongation at break, and in severe cases, surface powdering and cracking, thus affecting the service life of cables or optical fibers. Furthermore, in many regions, the operating environment for cables or optical fibers is characterized by high temperatures, high ultraviolet radiation, large diurnal temperature variations, and drought. Under these complex climatic conditions, polyethylene sheath materials are not only susceptible to photo-oxidative aging but may also experience environmental stress cracking due to temperature changes and external stress, further reducing the material's reliability.

[0004] To improve the weather resistance of colored polyethylene sheath materials, existing technologies typically involve adding additives such as UV absorbers, hindered amine light stabilizers, and antioxidants to enhance their anti-aging properties. For example, UV absorbers can absorb some UV radiation and convert it into heat energy, while hindered amine light stabilizers can capture free radicals generated during photo-oxidative aging, thereby slowing down the degradation process. However, single or simply compounded stabilizer systems still struggle to provide sufficient protection under long-term strong UV conditions, especially in colored systems lacking carbon black shielding, resulting in inadequate weather resistance. Furthermore, existing polyethylene sheath materials often employ single high-density polyethylene or simple blends of high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE), whose resistance to environmental stress cracking and low-temperature impact still requires further improvement. Under complex environmental conditions, the material may experience stress concentration under long-term external forces and temperature changes, leading to microcracks that gradually propagate and ultimately cause sheath material failure.

[0005] Therefore, how to improve the long-term weather resistance of colored polyethylene sheath materials under strong ultraviolet radiation, high temperature and complex climatic conditions while maintaining good mechanical and processing properties, and improve their resistance to environmental stress cracking so that the weather resistance of the sheath material can reach 4000 hours, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to overcome at least one defect in the prior art and provide a colored high-density polyethylene sheath material with ideal weather resistance and aging resistance, and its preparation method, so that it has the advantages of excellent mechanical properties, excellent processability, and strong weather resistance, improves the long-term weather resistance of colored polyethylene sheath material under strong ultraviolet, high temperature and complex climatic conditions, and improves its resistance to environmental stress cracking, so that the weather resistance time of the sheath material can reach 4000 hours.

[0007] To achieve the above-mentioned objective, the present invention provides a colored weather-resistant 4000h high-density polyethylene sheath material, which comprises the following components by weight percentage: 90-95wt% colored weather-resistant polyethylene sheath material base material and 5-10wt% other auxiliary materials;

[0008] The colored weather-resistant polyethylene sheath material base material includes 40-45wt% polyethylene resin A, 30-35wt% polyethylene resin B, and 20-25wt% polyethylene resin C.

[0009] The other excipients include 1-3 wt% POE elastomer, 1-5 wt% anti-aging masterbatch, 0.2-0.6 wt% nano TiO2, 0.4-0.9 wt% light stabilizer, 0.4-0.8 wt% antioxidant, 0.1-0.2 wt% nucleating agent, 0.1-0.3 wt% lubricant, and 0.5-1.5 wt% acid absorbent.

[0010] Further, the polyethylene resin A is a high-density polyethylene resin with a density of 0.95±0.01g / cm³, a melt flow rate of 0.05-0.3g / 10min, a tensile strength ≥30MPa, an elongation at break ≥800%, and a yield strength ≥22MPa.

[0011] Further, the polyethylene resin B is a linear low-density polyethylene resin with a density of 0.92±0.005 g / cm³, a melt flow rate of 2.0±0.5 g / 10 min, a tensile strength ≥20 MPa, an elongation at break ≥800%, and a yield strength ≥8 MPa.

[0012] Further, the polyethylene resin C is a high-density polyethylene resin with a density of 0.95±0.01g / cm³, a melt flow rate of 0.35±0.1g / 10min, a tensile strength ≥30MPa, an elongation at break ≥800%, and a yield strength ≥26MPa.

[0013] Furthermore, the melt flow rate of the polyethylene resin A is lower than that of the polyethylene resin C.

[0014] Furthermore, the POE elastomer is an ethylene-octene copolymer elastomer;

[0015] The antioxidant masterbatch is a PE carrier with an antioxidant content of 45±0.5%.

[0016] The light stabilizer is a mixture of light stabilizer UV-531 and light stabilizer UV-770 in a 1:3 ratio;

[0017] The antioxidant is a 1:1 mixture of antioxidant AO-1010 and antioxidant AO-168.

[0018] The nucleating agent is a PE nucleating agent;

[0019] The lubricant is zinc stearate with a zinc oxide content of 12%;

[0020] The acid absorbent is a hydrotalcite-like substance.

[0021] This invention also provides a method for preparing the above-mentioned colored, weather-resistant 4000h high-density polyethylene sheath material, specifically including the following steps:

[0022] 1) By weight percentage, add 40-45wt% polyethylene resin A, 30-35wt% polyethylene resin B, and 20-25wt% polyethylene resin C into the mixer;

[0023] Simultaneously, 1-3 wt% POE elastomer, 1-5 wt% anti-aging masterbatch, 0.2-0.6 wt% nano TiO2, 0.4-0.9 wt% light stabilizer, 0.4-0.8 wt% antioxidant, 0.1-0.2 wt% nucleating agent, 0.1-0.3 wt% lubricant, and 0.5-1.5 wt% hydrotalcite are added to a mixer for premixing for 4-5 minutes to obtain a uniform premix.

[0024] 2) The premix obtained in step 1) is extruded through a twin-screw extruder. The screw speed of the twin-screw extruder is 300-380 rpm, and the temperature of the twin-screw extruder is set as follows: feeding section 180℃-200℃, plasticizing section 200℃-210℃, homogenizing section 190℃-210℃.

[0025] During the extrusion process, a vacuum exhaust system is used to evacuate the system, maintaining the pressure of the vacuum exhaust system between -0.07 and -0.095 MPa.

[0026] 3) After the extruded material is cooled by a water bath at a temperature of 50-60℃, it is fed into a pelletizer to granulate, thereby obtaining colored, weather-resistant 4000h high-density polyethylene sheathing material granules.

[0027] The components of the high-density polyethylene sheath material are weighed according to their weight percentages. The weighing accuracy of the colored weather-resistant polyethylene sheath material base is ±0.1kg, and the weighing accuracy of other auxiliary materials is ±0.01kg.

[0028] Step 3) also includes sieving to remove particles that do not meet the shape and size requirements.

[0029] In step 3), the particles must be of uniform size and there should be no long strips or clumped particles.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] The colored weather-resistant high-density polyethylene (HDPE) sheathing material of this invention exhibits significantly superior weather resistance and aging resistance compared to ordinary colored HDPE sheathing materials. In this colored weather-resistant HDPE sheathing material, the resin matrix utilizes high-density polyethylene (HDPE) with excellent processing performance and good overall properties, while a certain amount of linear low-density polyethylene (LLDPE) is added to improve the poor environmental stress cracking resistance of HDPE. Therefore, with these three resins as the matrix, the finished product possesses relatively stable mechanical properties and good processing performance. The combination of polyethylene resin A, polyethylene resin B, and polyethylene resin C is not merely a physical mixture, but rather utilizes molecular weight differences to provide excellent environmental stress cracking resistance through long-chain molecules and processing fluidity through short-chain molecules. This specific "high-low-medium" melt index combination forms an interpenetrating crystalline network structure during extrusion, thus maintaining structural stability for 4000 hours even without carbon black masking. This invention constructs a multi-peak system with a gradient molecular weight distribution within the matrix by precisely controlling the mass ratio of polyethylene resin A, polyethylene resin B, and polyethylene resin C. This multi-peak system features high-density polyethylene resin A with an extremely low melt flow rate (0.05-0.3 g / 10 min), which acts as the material's rigid framework. Its extremely long molecular chains span multiple crystal regions during crystallization, forming numerous bonded molecules and endowing the sheath material with extremely high tensile strength and elongation at break (≥800%). The introduction of linear low-density polyethylene resin B (LLDPE), utilizing its branched structure to act as a "flexible link" between long-chain molecules, significantly improves the stress cracking defect of high-density polyethylene. Combined with the use of a PE nucleating agent, the three resins with different molecular weight distributions induce the formation of a large number of fine and regular spherulites under an extrusion temperature gradient of 180-210℃. This microscopic interpenetrating network structure allows the material to effectively resist the attack of ultraviolet rays on the amorphous region even without carbon black shielding, ensuring that the mechanical properties retained after 4000 hours of xenon lamp aging are significantly better than those of traditional single-peak or bi-peak formulations.

[0032] Among the added excipients, a UV stabilization system was first constructed. This invention establishes a multi-level UV-resistant system consisting of nano-TiO2 + UV absorber + free radical scavenging system. The nano-TiO2 forms a UV reflective layer, compensating for the lack of carbon black's light-shielding ability in colored materials. UV-531, a commonly used UV absorber, absorbs UV light, preventing the generation of free radicals and thus inhibiting photo-oxidative aging. UV-770, a free radical scavenger, preferentially reacts with free radicals generated in the chain segments, thereby preventing further initiation of free radicals on the molecular chain. The synergistic stabilization system formed by the UV absorber and the hindered amine light stabilizer improves the long-term weather resistance of the material.

[0033] By introducing ethylene-octene copolymer elastomer as the POE elastomer, a typical "island structure" is constructed, with POE acting as the dispersed phase (islands) uniformly distributed within the continuous HDPE phase (sea). When the material is subjected to external impact or internal stress due to extreme temperature differences, the POE particles act as stress concentration points, inducing a large number of microcracks and shear bands in the HDPE matrix. The elastomer particles, spanning the crack walls, absorb energy through their own deformation, effectively preventing microcracks from evolving into macroscopic fracture, thereby improving the material's low-temperature impact performance.

[0034] The presence of long branches in the POE molecular chain allows it to form deep intermolecular entanglements with the amorphous regions of HDPE. In harsh environments with alternating wet and dry seasons, POE can absorb and relax internal stresses caused by environmental changes, preventing the molecular chains from breaking too quickly under chemical or physical stress. This ensures the material maintains structural integrity even after 4000 hours of extreme testing. Finally, one of the biggest challenges in colored sheathing materials is the dispersion of pigments and antioxidants. POE, with its low crystallinity, can better wet and encapsulate pigment particles (such as masterbatches) and light stabilizers. The elastomer segments provide more free volume space for antioxidant molecules, acting like a "warehouse" to lock in the additives and prevent them from migrating to the surface (blooming). This is crucial for maintaining the long-lasting aesthetics and weather resistance of colored sheathing.

[0035] Under high temperature and strong ultraviolet radiation, polyethylene substrates inevitably undergo photo-oxidative degradation, producing hydroperoxides and further decomposition into carboxylic acids, aldehydes, and ketones. Furthermore, trace amounts of catalyst residues such as magnesium chloride remaining from the polymerization process can release acidic substances in humid environments. Hydrotalcite-like compounds possess a unique layered double hydroxide structure, with positively charged layers and exchangeable anions between them. They can actively capture and adsorb acidic ions (such as Cl-) generated during degradation, acting like a "chemical sponge." -1 COO -1The layered double hydroxide (LDH) is fixed between the layers. By removing these acidic catalysts in time, the LDH interrupts the acid-catalyzed self-accelerating pathway of polyethylene degradation, thus slowing down the micro-cracking of the material at its source. Simultaneously, the synergistic effect of "activity preservation" with hindered amines (light stabilizer UV-770) is a key factor in extending the weather resistance from 2000h to 4000h. The light stabilizer UV-770 used in this invention belongs to the hindered amine class (HALS), and its effectiveness depends on maintaining an alkaline environment. If acidic substances accumulate in the system, HALS will undergo an acid-base neutralization reaction, generating inactive ammonium salts, leading to the complete loss of its free radical scavenging function. The LDH, as a highly efficient "acid scavenger," preferentially absorbs the attack of acidic substances for HALS, maintaining the acid-base balance within the matrix. This ensures that HALS can remain in an active state, efficiently cyclically capturing free radicals generated by chain segment degradation, extending the effective working life of HALS. Furthermore, the layered structure of the LDH also provides a certain degree of physical shielding at the microscopic level, slowing down the oxygen permeation rate. This combination of "hydrotalcite-like neutralizing acid protective layer + HALS dynamic free radical repair" allows the colored sheath material to retain tensile strength and elongation at break of over 68% even in the absence of carbon black protection, with the optimal solution reaching over 75%, significantly better than imported similar products (such as HE6068's 45%-53%).

[0036] Anti-aging masterbatch is a PE carrier masterbatch containing 45±0.5% antioxidant, primarily serving to block direct contact of ultraviolet light with the molecular chain, preventing breakage and the generation of free radicals. Addressing the extreme high temperatures and strong ultraviolet radiation of tropical regions, this invention designs an anti-aging system with internal and external dual-layer synergistic anchoring, solving the industry problem of easy migration and blooming of additives in colored sheathing materials. The anti-aging masterbatch selected in this invention uses PE as a carrier, forming an "additive micro-reservoir" through a high loading of 45±0.5%. Among them, the high molecular weight hindered phenolic antioxidant 1010, due to its large molecular volume and low volatility, has an excellent physical anchoring effect within the polyethylene matrix, making it difficult to migrate to the surface even during long-term oven aging at 110℃ for 240 hours. The light stabilizer UV-531 (ultraviolet absorber) and the light stabilizer UV-770 (free radical scavenger) are compounded in a specific ratio of 1:3 to construct a dynamic protective chain from "photon shielding" to "free radical termination." Simultaneously, UV-770, as a hindered amine stabilizer, can capture free radicals generated by molecular chain breakage, while UV-531 is responsible for absorbing harmful photons in the superficial layer. This compounding ratio ensures that, during 4000 hours of long-term exposure, the active ingredients diffuse from the "micro-reservoir" to the aging interface at a constant rate, maintaining the long-lasting stability of the sheath's surface color and tensile strength retention, thus solving the problem of later embrittlement caused by the loss of additives in conventional colored sheaths.

[0037] Zinc stearate with a zinc oxide content of 12% acts as a lubricant and stabilizer, ensuring good processing performance and improving product stability. Zinc stearate is a commonly used metal soap additive that provides both lubrication and auxiliary stabilization in polyethylene material systems. The zinc stearate molecule, composed of long-chain fatty acid structures and metal ions, exhibits significant hydrophobicity and low surface energy. During polyethylene melt processing, its molecules can form a low-friction interface between polymer chains, thereby reducing frictional resistance and improving material flowability, thus enhancing processing stability in extrusion granulation and sheath extrusion processes. In formulations, zinc stearate not only acts as a lubricant but also ensures initial thermal stability.

[0038] PE nucleating agents facilitate the faster formation of more and finer spherulites with regular structure and high crystal density during the production process, thereby improving the material's mechanical properties. They are primarily used to regulate the crystallization behavior and microstructure of the material. During the cooling process of molten polyethylene, nucleating agents provide numerous heterogeneous nucleation sites, making it easier for polyethylene molecular chains to form crystal structures, thus increasing the crystallization rate and shortening the crystallization time. Due to the increased number of nucleation sites, the size of the spherulites formed in polyethylene is significantly reduced, resulting in a more uniform crystal structure. This structural change improves the material's tensile strength, impact resistance, and dimensional stability. Simultaneously, the smaller spherulite structure reduces internal stress concentration, thereby improving the material's resistance to environmental stress cracking.

[0039] Antioxidant AO-1010 is a high-molecular-weight hindered phenolic antioxidant with low volatility and poor migration, effectively preventing thermal oxidative degradation of materials during long-term aging. Antioxidant AO-168 is a high-performance phosphite antioxidant; when used in combination with the main antioxidant AO-1010, it achieves a good synergistic effect, better ensuring that the performance of materials does not significantly decline under harsh environments.

[0040] By combining a reasonable polyethylene substrate with various functional additives, the colored weather-resistant 4000h high-density polyethylene sheath material of this invention can have good mechanical properties, processing technology, and excellent weather resistance and anti-aging properties. Attached Figure Description

[0041] Figure 1 These are the sheath material particles of the present invention; Figure 2 This invention relates to a finished sheathed wire. Detailed Implementation

[0042] To make the objectives, technical solutions, and effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described in this specification are merely for explaining the invention and are not intended to limit the invention.

[0043] Example 1

[0044] This embodiment provides a colored weather-resistant 4000h high-density polyethylene sheath material, which comprises the following components by weight percentage: 90wt% colored weather-resistant polyethylene sheath material base material and 10wt% other auxiliary materials;

[0045] The base material of the colored weather-resistant polyethylene sheath includes 40wt% polyethylene resin A, 30wt% polyethylene resin B, and 20wt% polyethylene resin C.

[0046] The other excipients include 3wt% POE elastomer, 5wt% anti-aging masterbatch, 0.5wt% nano TiO2, 0.4wt% light stabilizer, 0.4wt% antioxidant, 0.1wt% nucleating agent, 0.1wt% lubricant, and 0.5wt% acid absorbent.

[0047] Polyethylene resin A is a high-density polyethylene resin with a density of 0.94 g / cm³, a melt flow rate of 0.05 g / 10 min, a tensile strength of 30 MPa, an elongation at break of ≥800%, and a yield strength of 22 MPa.

[0048] Polyethylene resin B is a linear low-density polyethylene resin with a density of 0.915 g / cm³, a melt flow rate of 2.0 g / 10 min, a tensile strength of 20 MPa, an elongation at break of ≥800%, and a yield strength of 8 MPa.

[0049] Polyethylene resin C is a high-density polyethylene resin with a density of 0.94 g / cm³, a melt flow rate of 0.35 g / 10 min, a tensile strength of 30 MPa, an elongation at break of ≥800%, and a yield strength of 26 MPa.

[0050] POE elastomer is an ethylene-octene copolymer elastomer;

[0051] The antioxidant masterbatch uses a PE carrier and contains 45% antioxidant.

[0052] The light stabilizer is a mixture of light stabilizer UV-531 and light stabilizer UV-770 in a 1:3 ratio;

[0053] The antioxidant is a 1:1 mixture of antioxidant AO-1010 and antioxidant AO-168;

[0054] The nucleating agent is a PE nucleating agent;

[0055] The lubricant is zinc stearate with a zinc oxide content of 12%;

[0056] The acid absorbent is a hydrotalcite-like substance.

[0057] The relevant performance of Example 1 was tested according to national standards, and the relevant test results are shown in Table 1.

[0058] Table 1 Performance test results of Example 1

[0059]

[0060] Example 2

[0061] This embodiment provides a colored weather-resistant 4000h high-density polyethylene sheath material, which comprises the following components by weight percentage: 95wt% colored weather-resistant polyethylene sheath material base material and 5wt% other auxiliary materials;

[0062] The base material of the colored weather-resistant polyethylene sheath includes 45wt% polyethylene resin A, 30wt% polyethylene resin B, and 20wt% polyethylene resin C.

[0063] The other excipients include 1 wt% POE elastomer, 1 wt% anti-aging masterbatch, 0.3 wt% nano TiO2, 0.9 wt% light stabilizer, 0.8 wt% antioxidant, 0.2 wt% nucleating agent, 0.3 wt% lubricant, and 0.5 wt% acid absorbent.

[0064] Polyethylene resin A is a high-density polyethylene resin with a density of 0.96 g / cm³, a melt flow rate of 0.3 g / 10 min, a tensile strength of 35 MPa, an elongation at break of ≥800%, and a yield strength of 25 MPa.

[0065] Polyethylene resin B is a linear low-density polyethylene resin with a density of 0.925 g / cm³, a melt flow rate of 2.5 g / 10 min, a tensile strength of 25 MPa, an elongation at break of ≥800%, and a yield strength of 10 MPa.

[0066] Polyethylene resin C is a high-density polyethylene resin with a density of 0.96 g / cm³, a melt flow rate of 0.34 g / 10 min, a tensile strength of 35 MPa, an elongation at break of ≥800%, and a yield strength of 30 MPa.

[0067] POE elastomer is an ethylene-octene copolymer elastomer;

[0068] The antioxidant masterbatch uses a PE carrier and contains 45% antioxidant.

[0069] The light stabilizer is a mixture of light stabilizer UV-531 and light stabilizer UV-770 in a 1:3 ratio;

[0070] The antioxidant is a 1:1 mixture of antioxidant AO-1010 and antioxidant AO-168;

[0071] The nucleating agent is a PE nucleating agent;

[0072] The lubricant is zinc stearate with a zinc oxide content of 12%;

[0073] The acid absorbent is a hydrotalcite-like substance.

[0074] The relevant performance of Example 2 was tested according to national standards, and the relevant test results are shown in Table 2.

[0075] Table 2 Performance test results of Example 2

[0076]

[0077] Example 3

[0078] This embodiment provides a colored weather-resistant 4000h high-density polyethylene sheath material, which comprises the following components by weight percentage: 95wt% colored weather-resistant polyethylene sheath material base material and 5wt% other auxiliary materials;

[0079] The base material of the colored weather-resistant polyethylene sheath includes 40wt% polyethylene resin A, 35wt% polyethylene resin B, and 20wt% polyethylene resin C.

[0080] The other excipients include 1 wt% POE elastomer, 1 wt% anti-aging masterbatch, 0.2 wt% nano TiO2, 0.4 wt% light stabilizer, 0.6 wt% antioxidant, 0.1 wt% nucleating agent, 0.2 wt% lubricant, and 1.5 wt% acid absorbent.

[0081] Polyethylene resin A is a high-density polyethylene resin with a density of 0.95 g / cm³, a melt flow rate of 0.2 g / 10 min, a tensile strength of 40 MPa, an elongation at break of ≥800%, and a yield strength of 30 MPa.

[0082] Polyethylene resin B is a linear low-density polyethylene resin with a density of 0.92 g / cm³, a melt flow rate of 2.5 g / 10 min, a tensile strength of 30 MPa, an elongation at break of ≥800%, and a yield strength of 12 MPa.

[0083] Polyethylene resin C is a high-density polyethylene resin with a density of 0.95 g / cm³, a melt flow rate of 0.45 g / 10 min, a tensile strength of 40 MPa, an elongation at break of ≥800%, and a yield strength of 33 MPa.

[0084] POE elastomer is an ethylene-octene copolymer elastomer;

[0085] The antioxidant masterbatch uses a PE carrier and contains 45% antioxidant.

[0086] The light stabilizer is a mixture of light stabilizer UV-531 and light stabilizer UV-770 in a 1:3 ratio;

[0087] The antioxidant is a 1:1 mixture of antioxidant AO-1010 and antioxidant AO-168;

[0088] The nucleating agent is a PE nucleating agent;

[0089] The lubricant is zinc stearate with a zinc oxide content of 12%;

[0090] The acid absorbent is a hydrotalcite-like substance.

[0091] The relevant performance of Example 3 was tested according to national standards, and the relevant test results are shown in Table 3.

[0092] Table 3 Performance test results of Example 3

[0093]

[0094] Example 4

[0095] This embodiment provides a colored weather-resistant 4000h high-density polyethylene sheath material, which comprises the following components by weight percentage: 95wt% colored weather-resistant polyethylene sheath material base material and 5wt% other auxiliary materials;

[0096] The base material of the colored weather-resistant polyethylene sheath includes 40wt% polyethylene resin A, 30wt% polyethylene resin B, and 25wt% polyethylene resin C.

[0097] The other excipients include 1 wt% POE elastomer, 1 wt% anti-aging masterbatch, 0.6 wt% nano TiO2, 0.5 wt% light stabilizer, 0.4 wt% antioxidant, 0.2 wt% nucleating agent, 0.3 wt% lubricant, and 1 wt% acid absorbent.

[0098] Polyethylene resin A is a high-density polyethylene resin with a density of 0.95 g / cm³, a melt flow rate of 0.1 g / 10 min, a tensile strength of 50 MPa, an elongation at break of ≥800%, and a yield strength of 38 MPa.

[0099] Polyethylene resin B is a linear low-density polyethylene resin with a density of 0.92 g / cm³, a melt flow rate of 2.0 g / 10 min, a tensile strength of 45 MPa, an elongation at break of ≥800%, and a yield strength of 24 MPa.

[0100] Polyethylene resin C is a high-density polyethylene resin with a density of 0.95 g / cm³, a melt flow rate of 0.35 g / 10 min, a tensile strength of 45 MPa, an elongation at break of ≥800%, and a yield strength of 38 MPa.

[0101] POE elastomer is an ethylene-octene copolymer elastomer;

[0102] The antioxidant masterbatch uses a PE carrier and contains 45% antioxidant.

[0103] The light stabilizer is a mixture of light stabilizer UV-531 and light stabilizer UV-770 in a 1:3 ratio;

[0104] The antioxidant is a 1:1 mixture of antioxidant AO-1010 and antioxidant AO-168;

[0105] The nucleating agent is a PE nucleating agent;

[0106] The lubricant is zinc stearate with a zinc oxide content of 12%;

[0107] The acid absorbent is a hydrotalcite-like substance.

[0108] The relevant performance of Example 4 was tested according to national standards, and the relevant test results are shown in Table 4.

[0109] Table 4 Performance test results of Example 4

[0110]

[0111] Example 5

[0112] The present invention also provides a method for preparing the colored weather-resistant 4000h high-density polyethylene sheath material in the above embodiments, specifically including the following steps:

[0113] 1) By weight percentage, add 45wt% polyethylene resin A, 30wt% polyethylene resin B, and 20wt% polyethylene resin C into the mixer;

[0114] Simultaneously, 1wt% POE elastomer, 1wt% anti-aging masterbatch, 0.3wt% nano TiO2, 0.9wt% light stabilizer, 0.8wt% antioxidant, 0.2wt% nucleating agent, 0.3wt% lubricant, and 0.5wt% hydrotalcite-like material are added to the mixer for premixing for 5 minutes to obtain a uniform premix.

[0115] 2) The premix obtained in step 1) is extruded through a twin-screw extruder. The screw speed of the twin-screw extruder is 300 rpm, and the temperature of the twin-screw extruder is set as follows: feeding section 180℃, plasticizing section 200℃, homogenizing section 190℃.

[0116] During the extrusion process, a vacuum exhaust system is used to maintain a pressure of -0.07 MPa.

[0117] 3) After the extruded material is cooled by a water bath at 50°C, it is fed into a pelletizer to obtain colored, weather-resistant 4000h high-density polyethylene sheathing material granules.

[0118] Step 1) further includes weighing each component of the high-density polyethylene sheath material according to the weight percentage, wherein the weighing accuracy of the colored weather-resistant polyethylene sheath material base material is ±0.1kg, and the weighing accuracy of other auxiliary materials is ±0.01kg.

[0119] Step 3) also includes sieving to remove particles that do not meet the shape and size requirements.

[0120] Step 3) requires uniform particle size, avoiding elongated or clumped particles, and removing particles that do not meet the shape and size requirements. The product is then mixed in a large silo to improve material uniformity. Finally, it is packaged in 12-mil PE plastic bags. Figure 1 The image shown is of the finished sheath material granules of the present invention. Figure 2 The finished sheathed wire is made from the sheathing material particles of the present invention.

[0121] Example 6

[0122] To verify the impact of the selection of each raw material on the performance of the sheath material, a formula screening and verification test was carried out during the formula development stage. The components and basic performance test results of the test formulas 1#-5# are shown in Table 5.

[0123] Table 5. Formulations (wt%, based on 180kg / batch) and basic performance test results from the formulation screening and validation test.

[0124]

[0125] In formulations 1# to 4#, the polyethylene resins A, B, and C used are the same as in Example 1, namely: polyethylene resin A is a high-density polyethylene resin with a density of 0.94 g / cm³, a melt flow rate of 0.05 g / 10 min, a tensile strength of 30 MPa, an elongation at break ≥800%, and a yield strength of 22 MPa; polyethylene resin B is a linear low-density polyethylene resin with a density of 0.915 g / cm³, a melt flow rate of 2.0 g / 10 min, a tensile strength of 20 MPa, an elongation at break ≥800%, and a yield strength of 8 MPa; and polyethylene resin C is a high-density polyethylene resin with a density of 0.94 g / cm³, a melt flow rate of 0.35 g / 10 min, a tensile strength of 30 MPa, an elongation at break ≥800%, and a yield strength of 26 MPa. The resins used in formulation #5 are the same as those in Example 2: Polyethylene resin A is a high-density polyethylene resin with a density of 0.96 g / cm³, a melt flow rate of 0.3 g / 10 min, a tensile strength of 35 MPa, an elongation at break ≥800%, and a yield strength of 25 MPa; Polyethylene resin B is a linear low-density polyethylene resin with a density of 0.925 g / cm³, a melt flow rate of 2.5 g / 10 min, a tensile strength of 25 MPa, an elongation at break ≥800%, and a yield strength of 10 MPa; Polyethylene resin C is a high-density polyethylene resin with a density of 0.96 g / cm³, a melt flow rate of 0.34 g / 10 min, a tensile strength of 35 MPa, an elongation at break ≥800%, and a yield strength of 30 MPa.

[0126] The antioxidant masterbatch is a PE carrier with an antioxidant content of 45%; the POE elastomer is an ethylene-octene copolymer elastomer (brand name J-2200, 39001); the antioxidant AO-1010 is a hindered phenolic main antioxidant (brand name KF-01); the nano-TiO2 and PE nucleating agent are consistent with the raw materials used in each example. Formulas 1# and 2# use calcium masterbatch of equal mass to replace the antioxidant masterbatch as a filler control formula without an antioxidant system; the only difference between 1# and 2# is the POE elastomer brand. A positive oven aging change rate indicates improved performance compared to before aging, caused by post-crystallization during oven aging. During oven aging at 110℃ for 240h, the material exhibits two competing effects: post-crystallization (secondary crystallization) and thermo-oxidative degradation. Post-crystallization increases crystallinity and tensile strength, and the relaxation of processing internal stress also facilitates the recovery of elongation at break; thermo-oxidative degradation, on the other hand, causes molecular chain breakage and performance degradation. In formulations 1#-3#, post-crystallization and internal stress relaxation effects dominate, resulting in positive changes in tensile strength and elongation at break. In formulations 4# and 5#, inorganic particles such as hydrotalcite play a heterogeneous nucleation role during extrusion granulation, leading to more complete crystallization during the molding stage. This reduces the contribution of post-crystallization, and the thermo-oxidative degradation effect becomes relatively dominant, resulting in slightly negative changes in the rates of change. However, the absolute values ​​of these changes are all less than 15%, meeting the relevant standard requirements.

[0127] Formulas #4 and #5 correspond to Example 1 and Example 2, respectively. Formulas #1-#3 were previously screened and eliminated, and were not subjected to the 4000-hour xenon lamp aging test.

[0128] As shown in Table 5, the only difference between formulations #1 and #2 is the POE elastomer grade. The environmental stress cracking time of #2 (679h) is significantly higher than that of #1 (428h), indicating that the selection of the POE elastomer grade has a significant impact on environmental stress cracking performance. Therefore, formulations #3-#5 all use grade 39001. The only difference between formulations #2 and #3 is that #3 uses anti-aging masterbatch instead of calcium masterbatch in #2 as a control. After 1008h xenon lamp aging, the tensile strength retention rate and elongation at break retention rate of #3 (84% / 83%) are significantly higher than those of #2 (75% / 72%), indicating that the anti-aging masterbatch... The addition of [the substance] plays a decisive role in improving the long-term weather resistance of the sheath material. Compared with #3, #4 further added hydrotalcite-like material and adjusted the compounding ratio of UV-531 and UV-770 from 1:1 to 1:3 (the total amount of light stabilizer remains unchanged). The retention rate after 1008h xenon lamp aging was further increased from 84% / 83% to 85% / 85%, indicating that the combination of hydrotalcite-like material and the light stabilizer system compounded in a 1:3 ratio is beneficial to maintaining the long-term weather resistance of the sheath material. The formulations of #4 and #5 correspond to Example 1 and Example 2, respectively, and the corresponding formulations all passed the 4000h xenon lamp aging test (see Table 1 and Table 2).

[0129] Comparative Example 1

[0130] This comparative example uses imported brand new high-density polyethylene sheath material HE6068, and its performance was tested using the same method. The performance test results of Examples 1 to 4 and the comparative example are shown in Table 6.

[0131] Table 6 Performance test results of the examples and comparative examples

[0132]

[0133] Product extrusion process performance verification: Based on the above experimental data, Example 2 showed the best overall performance and the data was relatively stable. Therefore, Example 2 was ultimately selected to be compared with imported new high-density polyethylene sheath material HE6068 for optical cable extrusion. The extruder model was SJ90×25 (screw diameter 90mm, length-to-diameter ratio 25:1), and the equipment manufacturer was Zhejiang Jinhu Plastic Machinery Co., Ltd. The optical cable model selected for the trial extrusion was ordinary steel tape optical cable with an outer diameter of 8.0-9.0mm. The normal production speed was 100m / min. The high-density polyethylene sheath material of this invention and the imported new high-density polyethylene sheath material HE6068 were extruded at normal extrusion temperatures of 160-180-200-220-240-240-245-245-245. The results showed that the processing temperature of this product needs to be slightly higher than that of HE6068. The extruded surface was also smooth and delicate, and the appearance met the process requirements.

[0134] Cable performance verification: Since the properties of the sheath material particles and the processing performance both met the requirements, further cable-making experiments were conducted. The test results are shown in Table 7.

[0135] Table 7 Cable performance testing of Example 2 and Comparative Example 1

[0136]

[0137] Based on the above experimental data, the tensile strength and elongation at break of the HDPE product granules and cables of this invention are slightly better than HE6068. However, during the cable aging performance test, the change rate of tensile strength after aging is significantly greater than that of HE6068. In the 4000h xenon lamp aging test, the mechanical property retention rate of this invention is significantly better than that of HE6068, which meets the requirements. The main reason for this is that the sheath material is subjected to high temperature and traction during the cable formation process, which causes the material to undergo orientation, resulting in a higher crystallinity compared to the granules. Therefore, both materials showed increased strength in the cable formation test. However, during the aging process, the orientation behavior disappears, leading to a slight decrease in tensile strength. The synthetically produced polyethylene resin still has better resistance to heat aging than modified resin. However, in the 4000h weathering test, HE6068's retention rate decreased significantly due to the lack of anti-aging components and resistance to long-term photo-oxidative aging. This invention, through the structure of anti-aging masterbatch and light stabilizer, successfully achieves a higher retention rate in long-term weathering tests.

[0138] By rationally selecting resin substrates and combining various additives with different functions, the high-density polyethylene sheath material of this invention has good mechanical properties, processing performance, and excellent anti-aging and weather resistance.

[0139] Based on 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 protection scope of the claims of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. A colored, weather-resistant, 4000h high-density polyethylene sheathing material, characterized in that, By weight percentage, it comprises the following components: 90-95 wt% colored weather-resistant polyethylene sheathing material base and 5-10 wt% other auxiliary materials; The colored weather-resistant polyethylene sheath material base material includes 40-45wt% polyethylene resin A, 30-35wt% polyethylene resin B, and 20-25wt% polyethylene resin C. The other excipients include 1-3 wt% POE elastomer, 1-5 wt% anti-aging masterbatch, 0.2-0.6 wt% nano TiO2, 0.4-0.9 wt% light stabilizer, 0.4-0.8 wt% antioxidant, 0.1-0.2 wt% nucleating agent, 0.1-0.3 wt% lubricant, and 0.5-1.5 wt% acid absorbent. The polyethylene resin A is a high-density polyethylene resin with a density of 0.95±0.01g / cm³, a melt flow rate of 0.05-0.3g / 10min, a tensile strength ≥30MPa, an elongation at break ≥800%, and a yield strength ≥22MPa. The polyethylene resin B is a linear low-density polyethylene resin with a density of 0.92±0.005 g / cm³, a melt flow rate of 2.0±0.5 g / 10 min, a tensile strength ≥20 MPa, an elongation at break ≥800%, and a yield strength ≥8 MPa. The polyethylene resin C is a high-density polyethylene resin with a density of 0.95±0.01g / cm³, a melt flow rate of 0.35±0.1g / 10min, a tensile strength ≥30MPa, an elongation at break ≥800%, and a yield strength ≥26MPa. Furthermore, the melt flow rate of the polyethylene resin A is lower than that of the polyethylene resin C. The POE elastomer is an ethylene-octene copolymer elastomer; The antioxidant masterbatch is a PE carrier with an antioxidant content of 45±0.5%. The light stabilizer is a mixture of light stabilizer UV-531 and light stabilizer UV-770 in a 1:3 ratio; The antioxidant is a 1:1 mixture of antioxidant AO-1010 and antioxidant AO-168. The nucleating agent is a PE nucleating agent; The lubricant is zinc stearate with a zinc oxide content of 12%; The acid absorbent is a hydrotalcite-like substance.

2. A method for preparing the colored, weather-resistant 4000h high-density polyethylene sheath material according to claim 1, characterized in that, Includes the following steps: 1) By weight percentage, add 40-45wt% polyethylene resin A, 30-35wt% polyethylene resin B, and 20-25wt% polyethylene resin C into the mixer; Simultaneously, 1-3 wt% POE elastomer, 1-5 wt% anti-aging masterbatch, 0.2-0.6 wt% nano TiO2, 0.4-0.9 wt% light stabilizer, 0.4-0.8 wt% antioxidant, 0.1-0.2 wt% nucleating agent, 0.1-0.3 wt% lubricant, and 0.5-1.5 wt% hydrotalcite are added to a mixer for premixing for 4-5 minutes to obtain a uniform premix. 2) The premix obtained in step 1) is extruded through a twin-screw extruder. The screw speed of the twin-screw extruder is 300-380 rpm, and the temperature of the twin-screw extruder is set as follows: feeding section 180℃-200℃, plasticizing section 200℃-210℃, homogenizing section 190℃-210℃. During the extrusion process, a vacuum exhaust system is used to evacuate the system, maintaining the pressure of the vacuum exhaust system between -0.07 and -0.095 MPa. 3) After the extruded material is cooled by a water bath at a temperature of 50-60℃, it is fed into a pelletizer to granulate, thereby obtaining colored, weather-resistant 4000h high-density polyethylene sheathing material granules.

3. A method for preparing the colored, weather-resistant 4000h high-density polyethylene sheath material according to claim 2, characterized in that, Step 1) further includes weighing each component of the high-density polyethylene sheath material according to the weight percentage, wherein the weighing accuracy of the colored weather-resistant polyethylene sheath material base material is ±0.1kg, and the weighing accuracy of other auxiliary materials is ±0.01kg.

4. A method for preparing the colored, weather-resistant 4000h high-density polyethylene sheath material according to claim 2, characterized in that, Step 3) also includes sieving to remove particles that do not meet the shape and size requirements, requiring that the particles be of uniform size and that there be no long strips or clumped particles.

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