Double-layer polyolefin heat shrink tubing and preparation method thereof

Abstract

The present invention relates to the technical field of heat shrinkable tube preparation, and in particular to a method for preparing a double-layer polyolefin heat shrinkable tube, comprising: preparing a first mixed stock solution using a first mass ratio; preparing a second mixture stock solution using a second mass ratio, and preparing a heat shrinkable outer layer masterbatch; preparing a third mixture stock solution using a third mass ratio; determining the actual color value of the heat shrinkable outer layer masterbatch, and adjusting and correcting the second mass ratio according to the result; determining the actual viscosity of the third mixture stock solution, and adjusting and correcting the third mass ratio according to the result; preparing a preset experimental double-layer polyolefin heat shrinkable tube, and determining its actual tensile strength change rate, and obtaining and calculating a correction coefficient according to the result. The present invention calculates the correction coefficient in the current preparation process so that the final prepared finished product can achieve the required antioxidant properties while avoiding the influence of other properties of the finished product due to excessive addition of materials.

Description

Technical Field

[0001] The invention relates to the technical field of heat shrinkable tube preparation, and in particular to a double-layer polyolefin heat shrinkable tube and a preparation method thereof. Background Art

[0002] Heat shrink tubing is a plastic tubing with good flexibility and temperature resistance. It can shrink when heated, so that it can tightly wrap around pipes, cables or other round objects to play a role in sealing, protection and insulation. In the preparation process of double-layer polyolefin heat shrink tubing, oxidation resistance is an important consideration. Traditional polyolefin materials are prone to oxidation during high-temperature processing and long-term outdoor use, resulting in reduced product performance and greatly shortened service life. In existing technologies, antioxidants are usually added to improve the oxidation resistance of polyolefin materials. However, traditional antioxidants have some problems, such as poor stability, strong migration and high toxicity.

[0003] In order to solve the above problems, researchers have proposed a possible solution. By adopting nanotechnology, nanofillers are added to the polyolefin matrix, or specific olefins are used to form olefin copolymers with better oxidation resistance to improve the oxidation resistance of polyolefin materials, so as to more effectively hinder the oxidation reaction of polyolefin molecules and improve the mechanical properties and thermal stability of the materials. How to add such polyolefin materials to achieve the required oxidation resistance of the desired double-layer polyolefin heat shrinkable tubing while avoiding excessive addition of materials to affect other properties of the desired double-layer polyolefin heat shrinkable tubing is a problem that needs to be urgently solved in the present invention.

[0004] Chinese Patent Publication No.: CN117467216A discloses a flame-retardant MPP power cable sheath and a preparation method thereof, which improves the oxidation resistance of the power cable sheath to be prepared and reduces its aging rate by adding antioxidant 1010 antioxidant 1098 and controlling the addition amount; it can be seen that in the preparation process of the double-layer polyolefin heat shrinkable tube, it is necessary to add an oxidant to improve the oxidation resistance of the prepared heat shrinkable tube. Therefore, there is a problem of how to add materials that can improve the oxidation resistance of the double-layer polyolefin heat shrinkable tube to achieve the oxidation resistance required for the required double-layer polyolefin heat shrinkable tube. Summary of the invention

[0005] To this end, the present invention provides a double-layer polyolefin heat shrinkable tube and a preparation method thereof, so as to overcome the problem in the prior art of achieving the desired anti-oxidation property of the double-layer polyolefin heat shrinkable tube while avoiding excessive addition of materials affecting other properties of the double-layer polyolefin heat shrinkable tube.

[0006] To achieve the above object, the present invention provides a method for preparing a double-layer polyolefin heat shrinkable tube, comprising:

[0007] Step S1, in a first preparation cycle, a first mixed stock solution is prepared by mixing an alpha olefin copolymer and a composite elastomer in a first mass ratio;

[0008] Step S2, mixing a lubricant and a colorant with the first mixed stock solution to obtain a second mixed stock solution, and using the obtained second mixed stock solution to prepare a heat shrinkable outer layer masterbatch, wherein the mass ratio of the colorant to the α-olefin copolymer is a second mass ratio;

[0009] The hot melt adhesive and the tackifying resin are mixed with the first mixed stock solution to obtain a third mixed stock solution, and a hot melt adhesive inner layer masterbatch is prepared using the third mixed stock solution, wherein the mass ratio of the tackifying resin to the α-olefin copolymer is a third mass ratio;

[0010] Step S3, obtaining the actual color value of the obtained heat shrinkable outer layer masterbatch, comparing and determining the actual color value of the heat shrinkable outer layer masterbatch using the preset standard color value and the preset standard color value fluctuation difference, and adjusting and correcting the second mass ratio according to the determination result;

[0011] Obtaining the actual viscosity of the third mixture stock solution, comparing and determining the actual viscosity of the third mixture stock solution using the preset standard viscosity and the preset standard viscosity fluctuation difference, and adjusting and correcting the third mass ratio according to the determination result;

[0012] Step S4, using the obtained heat shrinkable outer layer masterbatch and the obtained hot melt adhesive inner layer masterbatch to prepare a preset experimental double-layer polyolefin heat shrinkable sleeve, detecting and obtaining the actual tensile strength change rate of the obtained preset experimental double-layer polyolefin heat shrinkable sleeve, using the preset tensile strength change rate to compare and determine the actual tensile strength change rate, and obtaining and calculating the correction coefficient for the next preparation cycle according to the determination result;

[0013] Step S5, the next preparation cycle, using the correction coefficient of the next preparation cycle, the first mass ratio, the corrected second mass ratio and the corrected third mass ratio to calculate to obtain the actual first mass ratio, the actual second mass ratio and the actual third mass ratio, and using the actual first mass ratio, the actual second mass ratio and the actual third mass ratio to prepare the required target double-layer polyolefin heat shrinkable tubing.

[0014] Furthermore, in the step S3, the preset standard color value and the preset standard color value fluctuation difference are set, and the actual color determination interval is calculated and obtained according to the preset standard color value and the preset standard color value fluctuation difference;

[0015] In step S3, the actual color values ​​of several heat-shrinkable outer layer masterbatches are obtained and their average color value is calculated as the judgment color value, and the judgment color value is compared with the actual color judgment interval.

[0016] If the determined color value is within the actual color determination interval, directly taking the current second mass ratio as the corrected second mass ratio and continuing to execute;

[0017] in, Fp is the determined color value, xi is the actual color value of the ith heat-shrinkable outer layer masterbatch, and n is the number of actual color values ​​of the heat-shrinkable outer layer masterbatch obtained.

[0018] Furthermore, in step S3, if the determined color value is not within the actual color determination interval, the current second mass ratio is adjusted and corrected according to the determined color value and the preset standard color value;

[0019] Wherein, M2′=M2×[1-(Fp-Fb) / Fb], M2′ is the corrected second mass ratio, M2 is the current second mass ratio, Fp is the determined color value, and Fb is the preset standard color value.

[0020] Furthermore, in step S3, the preset standard viscosity and the preset standard viscosity fluctuation difference are further provided, and the maximum preset viscosity and the minimum preset viscosity are calculated according to the preset standard viscosity and the preset standard viscosity fluctuation difference, and the actual viscosity of the third mixture stock solution is compared with the maximum preset viscosity and the minimum preset viscosity, respectively.

[0021] If the actual viscosity is greater than or equal to the minimum preset viscosity and less than or equal to the maximum preset viscosity, directly taking the current third mass ratio as the corrected third mass ratio and continuing to execute;

[0022] Among them, η1=ηc-Δη, η2=ηc+Δη, η1 is the minimum preset viscosity, η2 is the maximum preset viscosity, ηc is the preset standard viscosity, and Δη is the preset standard viscosity fluctuation difference.

[0023] Furthermore, in step S3, if the actual viscosity is less than the minimum preset viscosity, the increased third mass ratio is obtained by calculation based on the actual viscosity and the preset standard viscosity as the corrected third mass ratio;

[0024] If the actual viscosity is greater than the maximum preset viscosity, a reduced third mass ratio is obtained by calculation based on the actual viscosity and the preset standard viscosity as the corrected third mass ratio;

[0025] Among them, M3'=M3+M3×(ηc-ηs) / ηc, M3″=M3-M3×(ηs-ηc) / ηc,

[0026] M3' is the third mass ratio after increasing, M3" is the third mass ratio after decreasing, M3 is the current third mass ratio, and ηs is the actual viscosity.

[0027] Further, in the step S4, the tensile strength before oxidation and the tensile strength after oxidation of the preset experimental double-layer polyolefin heat shrinkable tube prepared in the first preparation cycle are calculated and obtained respectively, and the actual tensile strength change rate of the preset experimental double-layer polyolefin heat shrinkable tube is obtained according to the obtained tensile strength before oxidation and the tensile strength after oxidation.

[0028] Among them, σs = (σ1-σ2) / σ1, σs is the actual tensile strength change rate, σ1 is the tensile strength before oxidation, and σ2 is the tensile strength after oxidation.

[0029] Furthermore, in step S4, the preset tensile strength change rate is set, and the obtained actual tensile strength change rate is compared with the preset tensile strength change rate.

[0030] If the actual tensile strength change rate is less than or equal to the preset tensile strength change rate, the correction coefficient of the next preparation cycle is corrected to 1;

[0031] If the actual tensile strength change rate is greater than the preset tensile strength change rate, a correction coefficient for the next preparation cycle is calculated according to the actual tensile strength change rate and the preset tensile strength change rate.

[0032] Further, in the step S4, if the actual tensile strength change rate is greater than the preset tensile strength change rate, a correction coefficient for the next preparation cycle is obtained based on the calculated actual tensile strength change rate and the preset tensile strength change rate.

[0033] Wherein, K=σs / σc×100%, K is the correction coefficient of the next preparation cycle, σs is the actual tensile strength change rate, and σc is the preset tensile strength change rate.

[0034] Further, in the step S5, the actual first mass ratio, the actual second mass ratio and the actual third mass ratio are calculated according to the obtained correction coefficient of the next preparation cycle to prepare the desired target double-layer polyolefin heat shrinkable tubing;

[0035] Among them, M1s=M1×K, M2s=M2'×K, M3s=M3'×K or M3s=M3"×K, M1s is the actual first mass ratio, M2s is the actual second mass ratio, and M3s is the actual third mass ratio.

[0036] Another aspect of the present invention provides a double-layer polyolefin heat shrinkable tube prepared based on any one of the above-mentioned methods for preparing a double-layer polyolefin heat shrinkable tube, comprising a heat shrinkable outer layer and a hot melt adhesive inner layer.

[0037] The heat shrinkable outer layer is prepared by mixing alpha olefin copolymer, composite elastomer, lubricant and colorant;

[0038] The hot melt adhesive inner layer is prepared by mixing alpha olefin copolymer, composite elastomer, hot melt adhesive and tackifying resin.

[0039] Compared with the prior art, the beneficial effects of the present invention are that, by adopting α-olefin copolymer as polyolefin material, the oxidation resistance of the double-layer polyolefin heat shrinkable tube to be prepared is improved, by comparing and judging the actual color value of the prepared heat shrink outer layer masterbatch, it is quickly determined whether it is necessary to adjust and correct the actual added mass of the lubricant in the current preparation process, by comparing and judging the actual viscosity of the prepared third mixture stock solution, it is quickly determined whether it is necessary to adjust and correct the actual added mass of the hot melt adhesive in the current preparation process, and by comparing and judging the actual tensile strength change rate of the prepared preset experimental double-layer polyolefin heat shrinkable tube, it is determined whether it is necessary to calculate the correction coefficient in the current preparation process, and calculate and obtain the required correction coefficient for the next preparation cycle according to the judgment result, and calculate the actual first mass ratio, the actual second mass ratio and the actual third mass ratio required in the preparation process of the next cycle through the obtained correction coefficient of the next preparation cycle, so that the double-layer polyolefin heat shrinkable tube finally prepared can achieve the required oxidation resistance while avoiding the excessive addition of materials affecting other properties of the double-layer polyolefin heat shrinkable tube.

[0040] Furthermore, by obtaining the actual color values ​​of multiple heat-shrinkable outer layer masterbatches and calculating the average value thereof as the judgment color value thereof, the actual color of the currently obtained heat-shrinkable outer layer masterbatch can be more accurately represented, and by setting the preset standard color value fluctuation difference, the actual color judgment interval thereof is calculated to expand the judgment range thereof, increase the error tolerance thereof, thereby reducing human errors and improving the consistency of judgment;

[0041] In particular, the color of the heat-shrinkable outer layer masterbatch obtained after adding the colorant is determined to reflect the actual amount of lubricant added in the current preparation process, so as to help production personnel observe and determine the actual amount of lubricant added in the current preparation process, and adjust the second mass ratio to adjust and correct the actual amount of lubricant added in the current preparation process, so as to achieve the purpose of controlling the actual amount of lubricant added, so that the actual amount of lubricant added can be within the required lubricant addition range, so as to ensure the actual production quality of the obtained heat-shrinkable outer layer masterbatch;

[0042] Further, the determination range of the actual viscosity of the obtained third mixture stock solution is determined by calculating the maximum preset viscosity and the minimum preset viscosity, and the actual viscosity of the obtained third mixture stock solution is determined to determine whether it is necessary to adjust and correct the actual ratio of the third mass ratio in the current preparation process;

[0043] In particular, the actual viscosity of the obtained third mixture stock solution is determined to reflect the actual amount of hot melt adhesive added in the current preparation process, and the actual amount of hot melt adhesive added in the current preparation process is adjusted and corrected by adjusting the third mass ratio so that the actual amount of hot melt adhesive added can be within the required hot melt adhesive addition range, thereby ensuring the performance stability of the obtained hot melt adhesive inner layer masterbatch;

[0044] Furthermore, by calculating the actual tensile strength change rate of the preset experimental double-layer polyolefin heat shrinkable tubing prepared in the first preparation cycle, and comparing it with the preset tensile strength change rate, it is determined whether the oxidation resistance of the preset experimental double-layer polyolefin heat shrinkable tubing prepared in the current preparation process meets the oxidation resistance of the double-layer polyolefin heat shrinkable tubing to be prepared, thereby determining whether it is necessary to adjust and correct the first mass ratio in the current preparation process;

[0045] In particular, the correction coefficient for the next preparation cycle is calculated by the actual tensile strength change rate of the preset experimental double-layer polyolefin heat shrinkable tubing obtained and the preset tensile strength change rate, and the actual first mass ratio, the actual second mass ratio and the actual third mass ratio of the double-layer polyolefin heat shrinkable tubing to be prepared are calculated and corrected to optimize the actual usage of the material, while ensuring that the double-layer polyolefin heat shrinkable tubing prepared in the next preparation cycle can achieve the required oxidation resistance, while avoiding excessive addition of materials to ensure balanced product performance;

[0046] Furthermore, by using α-olefin copolymers to increase the antioxidant properties of the polyolefin materials involved in the preparation, the antioxidant properties of the prepared double-layer polyolefin heat shrinkable tubing are improved, and by adjusting the weight ratio of the α-olefin copolymers involved in the preparation to control their antioxidant properties, it is avoided that the excessively high weight ratio affects other properties of the prepared double-layer polyolefin heat shrinkable tubing. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Flow chart of the preparation method of the double-layer polyolefin heat shrink tubing of this embodiment;

[0048] Figure 2 A decision logic diagram for adjusting and correcting the actual second mass ratio in this embodiment;

[0049] Figure 3The decision logic diagram for adjusting and correcting the third mass ratio in this embodiment;

[0050] Figure 4 A logic diagram for calculating the correction factor for the next preparation cycle for this embodiment;

[0051] Figure 5 Schematic diagram of the structure of the double-layer polyolefin heat shrink tubing of this embodiment. DETAILED DESCRIPTION

[0052] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0053] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0054] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0055] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0056] See also Figure 1 As shown, it is a flow chart of the method for preparing the double-layer polyolefin heat shrinkable tubing of this embodiment;

[0057] Specifically, this embodiment provides a method for preparing a double-layer polyolefin heat shrinkable tube, comprising:

[0058] Step S1, in a first preparation cycle, a first mixed stock solution is prepared by mixing an alpha olefin copolymer and a composite elastomer in a first mass ratio;

[0059] Step S2, mixing the lubricant and the colorant with the first mixed stock solution to obtain a second mixed stock solution, and using the obtained second mixed stock solution to prepare a heat shrinkable outer layer masterbatch, wherein the mass ratio of the colorant to the α-olefin copolymer is a second mass ratio;

[0060] The hot melt adhesive and the tackifying resin are mixed with the first mixed stock solution to prepare a third mixed stock solution, and a hot melt adhesive inner layer masterbatch is prepared using the third mixed stock solution, wherein the mass ratio of the tackifying resin to the alpha olefin copolymer is a third mass ratio;

[0061] Step S3, obtaining the actual color value of the obtained heat shrinkable outer layer masterbatch, comparing and judging the actual color value of the heat shrinkable outer layer masterbatch using the preset standard color value and the preset standard color value fluctuation difference, and adjusting and correcting the second mass ratio according to the judgment result;

[0062] Obtaining the actual viscosity of the third mixture stock solution, comparing and determining the actual viscosity of the third mixture stock solution using the preset standard viscosity and the preset standard viscosity fluctuation difference, and adjusting and correcting the third mass ratio according to the determination result;

[0063] Step S4, using the obtained heat shrink outer layer masterbatch and the obtained hot melt adhesive inner layer masterbatch to prepare a preset experimental double-layer polyolefin heat shrinkable tube, detecting and obtaining the actual tensile strength change rate of the obtained preset experimental double-layer polyolefin heat shrinkable tube, using the preset tensile strength change rate to compare and determine the actual tensile strength change rate, and obtaining and calculating the correction coefficient for the next preparation cycle according to the determination result;

[0064] Step S5, the next preparation cycle, using the correction coefficient of the next preparation cycle, the first mass ratio, the corrected second mass ratio and the corrected third mass ratio to calculate to obtain the actual first mass ratio, the actual second mass ratio and the actual third mass ratio, and using the actual first mass ratio, the actual second mass ratio and the actual third mass ratio to prepare the required target double-layer polyolefin heat shrinkable tubing.

[0065] In this embodiment, the first mass ratio is the mixing mass ratio of the α-olefin copolymer and the composite elastomer, the second mass ratio is the mixing mass ratio of the colorant in the added lubricant and colorant to the α-olefin copolymer added under the current first mass ratio, and the third mass ratio is the mixing mass ratio of the tackifying resin in the added hot melt adhesive and tackifying resin to the α-olefin copolymer added under the current first mass ratio, wherein the second mass ratio and the third mass ratio should be set according to the current addition ratio of the colorant and tackifying resin to the corresponding lubricant and hot melt adhesive, respectively. For example, if the addition ratio of the colorant to the lubricant in this embodiment is 1:1, that is, when M2=1, the second mass ratio used is the mass ratio of the lubricant required to be added to the second mixture stock solution obtained under the current first mass ratio when the desired lubrication degree is reached;

[0066] In the embodiment of the present invention, α-olefin copolymer is used as the polyolefin material to improve the oxidation resistance of the double-layer polyolefin heat shrinkable tube to be prepared, and the actual color value of the prepared heat shrink outer layer masterbatch is compared and determined to quickly determine whether it is necessary to adjust and correct the actual added mass of the lubricant in the current preparation process, and the actual viscosity of the prepared third mixture stock solution is compared and determined to quickly determine whether it is necessary to adjust and correct the actual added mass of the hot melt adhesive in the current preparation process, and the actual tensile strength change rate of the prepared preset experimental double-layer polyolefin heat shrinkable tube is compared and determined to determine whether it is necessary to calculate the correction coefficient in the current preparation process, and the correction coefficient of the next preparation cycle is calculated according to the judgment result, and the actual first mass ratio, the actual second mass ratio and the actual third mass ratio required in the preparation process of the next cycle are calculated by the obtained correction coefficient of the next preparation cycle, so that the double-layer polyolefin heat shrinkable tube finally prepared can achieve the required oxidation resistance while avoiding the excessive addition of materials affecting other properties of the double-layer polyolefin heat shrinkable tube.

[0067] Please continue to read Figure 2 As shown, it is a decision logic diagram for adjusting and correcting the actual second mass ratio in this embodiment;

[0068] Specifically, in step S3, a preset standard color value and a preset standard color value fluctuation difference are set, and the actual color determination interval is calculated and obtained according to the preset standard color value and the preset standard color value fluctuation difference;

[0069] In step S3, the actual color values ​​of several heat-shrinkable outer layer masterbatches are obtained and their average color value is calculated as the judgment color value, and the judgment color value is compared with the actual color judgment interval.

[0070] If the color value is determined to be within the actual color determination interval, the current second mass ratio is directly used as the corrected second mass ratio to continue execution;

[0071] in, Fp is the determined color value, xi is the actual color value of the ith heat-shrinkable outer layer masterbatch, and n is the number of actual color values ​​of the heat-shrinkable outer layer masterbatch obtained.

[0072] By obtaining the actual color values ​​of multiple heat-shrinkable outer layer masterbatches and calculating the average value thereof as the judgment color value thereof, the actual color of the currently obtained heat-shrinkable outer layer masterbatches can be represented more accurately, and the actual color judgment interval thereof can be calculated by setting the fluctuation difference of the preset standard color value, so as to expand the judgment range thereof, increase the error tolerance thereof, reduce human errors, and improve the consistency of judgment;

[0073] In this embodiment, the preset standard color value should be selected according to the color of the colorant used. For example, when the colorant used is carbon black, the sum of the three values ​​in the RGB value (0, 0, 0) of carbon black is taken as the preset standard color value selected at this time, that is, the preset standard color value in this embodiment is 0+0+0=0, and the fluctuation difference of the preset standard color value is affected by factors such as site lighting, dyeing impurities and the color of the additive itself. Therefore, it should also be selected in combination with the actual preparation process, but generally speaking, the value of the fluctuation difference of the preset standard color value should not be greater than 40.

[0074] Specifically, in step S3, if the determined color value is not within the actual color determination interval, the current second mass ratio is adjusted and corrected according to the determined color value and the preset standard color value;

[0075] Wherein, M2′=M2×[1-(Fp-Fb) / Fb], M2′ is the corrected second mass ratio, M2 is the current second mass ratio, Fp is the determined color value, and Fb is the preset standard color value.

[0076] By judging the color of the heat-shrinkable outer layer masterbatch obtained after adding the colorant, the actual amount of lubricant added in the current preparation process can be reflected, so as to help production personnel observe and judge the actual amount of lubricant added in the current preparation process, and by adjusting the second mass ratio, the actual amount of lubricant added in the current preparation process can be adjusted and corrected, so as to achieve the purpose of controlling the actual amount of lubricant added, so that the actual amount of lubricant added can be within the required lubricant addition range, so as to ensure the actual production quality of the obtained heat-shrinkable outer layer masterbatch;

[0077] That is, when the color value is determined to be not within the actual color determination range, it means that the actual amount of lubricant added under the current second mass ratio M2 is less than or more than the normal amount of lubricant added under the current first mass ratio M1. Therefore, the current second mass ratio M2 is adjusted and corrected to obtain a second mass ratio M2 that can meet the normal amount of lubricant added under the current first mass ratio M1, that is, a corrected second mass ratio M2'.

[0078] Please continue to read Figure 3 As shown, it is a decision logic diagram for adjusting and correcting the third mass ratio in this embodiment;

[0079] Specifically, in step S3, a preset standard viscosity and a preset standard viscosity fluctuation difference are further provided, and a maximum preset viscosity and a minimum preset viscosity are calculated according to the preset standard viscosity and the preset standard viscosity fluctuation difference, and the actual viscosity of the third mixture stock solution is compared with the maximum preset viscosity and the minimum preset viscosity, respectively.

[0080] If the actual viscosity is greater than or equal to the minimum preset viscosity and less than or equal to the maximum preset viscosity, the current third mass ratio is directly used as the corrected third mass ratio to continue execution;

[0081] Among them, η1=ηc-Δη, η2=ηc+Δη, η1 is the minimum preset viscosity, η2 is the maximum preset viscosity, ηc is the preset standard viscosity, and Δη is the preset standard viscosity fluctuation difference.

[0082] Determining the determination range of the actual viscosity of the obtained third mixture stock solution by calculating the maximum preset viscosity and the minimum preset viscosity, and determining whether it is necessary to adjust and correct the actual ratio of the third mass ratio in the current preparation process by determining the actual viscosity of the obtained third mixture stock solution;

[0083] In this embodiment, the preset standard viscosity should be selected accordingly according to the type of thickening resin used. For example, if the thickening resin used in this embodiment is a polyester resin, in order to meet the bonding strength and heat resistance of the hot melt adhesive in the prepared third mixed stock solution, the selected preset standard viscosity should not be less than 1000 centipoise. The fluctuation difference of the preset standard viscosity is affected by factors such as the preparation process, the heat resistance of the hot melt adhesive inner layer and the viscosity of the hot melt adhesive itself. Therefore, it should also be selected in combination with the actual preparation process. However, in order to meet the normal bonding strength and heat resistance required for the final hot melt adhesive inner layer, the selected preset standard viscosity fluctuation difference should not be greater than 500 centipoise.

[0084] Specifically, in step S3, if the actual viscosity is less than the minimum preset viscosity, the increased third mass ratio is obtained as the corrected third mass ratio according to the actual viscosity and the preset standard viscosity;

[0085] If the actual viscosity is greater than the maximum preset viscosity, the reduced third mass ratio is obtained as the corrected third mass ratio based on the actual viscosity and the preset standard viscosity;

[0086] Among them, M3'=M3+M3×(ηc-ηs) / ηc, M3″=M3-M3×(ηs-ηc) / ηc,

[0087] M3' is the third mass ratio after increasing, M3" is the third mass ratio after decreasing, M3 is the current third mass ratio, and ηs is the actual viscosity.

[0088] The actual viscosity of the obtained third mixture stock solution is determined to reflect the actual amount of hot melt adhesive added in the current preparation process, and the actual amount of hot melt adhesive added in the current preparation process is adjusted and corrected by adjusting the third mass ratio so that the actual amount of hot melt adhesive added can be within the required hot melt adhesive addition range, thereby ensuring the performance stability of the obtained hot melt adhesive inner layer masterbatch;

[0089] That is, when ηs<η1, it means that the actual viscosity of the third mixture stock solution currently obtained is seriously lower than the normal viscosity of the third mixture stock solution required to be obtained under the current first mass ratio M1, wherein the actual amount of hot melt adhesive added cannot meet the actual amount of hot melt adhesive added under the current first mass ratio M1, and the current second mass ratio M3 should be increased and corrected to obtain a third mass ratio M3 that can meet the normal amount of hot melt adhesive added under the current first mass ratio M1, that is, to obtain the increased third mass ratio M3';

[0090] When ηs>η2, it means that the actual viscosity of the third mixture stock solution currently obtained has seriously exceeded the normal viscosity of the third mixture stock solution required to be obtained under the current first mass ratio M1, wherein the actual amount of hot melt adhesive added exceeds the actual amount of hot melt adhesive added under the current first mass ratio M1, and the current second mass ratio M3 should be reduced and corrected to obtain a third mass ratio M3 that can meet the normal amount of hot melt adhesive added under the current first mass ratio M1, that is, to obtain a reduced third mass ratio M3".

[0091] Please continue to read Figure 4 As shown, it is a logic diagram for calculating the correction coefficient of the next preparation cycle in this embodiment;

[0092] Specifically, in step S4, the tensile strength before oxidation and the tensile strength after oxidation of the preset experimental double-layer polyolefin heat shrinkable tubing prepared in the first preparation cycle are calculated and obtained respectively, and the actual tensile strength change rate of the preset experimental double-layer polyolefin heat shrinkable tubing is obtained according to the obtained tensile strength before oxidation and the tensile strength after oxidation.

[0093] Among them, σs = (σ1-σ2) / σ1, σs is the actual tensile strength change rate, σ1 is the tensile strength before oxidation, and σ2 is the tensile strength after oxidation.

[0094] By calculating the actual tensile strength change rate of the preset experimental double-layer polyolefin heat shrinkable tubing obtained in the first preparation cycle and comparing it with the preset tensile strength change rate, it is determined whether the oxidation resistance of the preset experimental double-layer polyolefin heat shrinkable tubing prepared in the current preparation process meets the oxidation resistance of the double-layer polyolefin heat shrinkable tubing to be prepared, thereby determining whether it is necessary to adjust and correct the first mass ratio in the current preparation process.

[0095] Specifically, in step S4, a preset tensile strength change rate is set, and the actual tensile strength change rate obtained is compared with the preset tensile strength change rate.

[0096] If the actual tensile strength change rate is less than or equal to the preset tensile strength change rate, the correction coefficient of the next preparation cycle is corrected to 1;

[0097] If the actual tensile strength change rate is greater than the preset tensile strength change rate, a correction factor for the next preparation cycle is calculated based on the actual tensile strength change rate and the preset tensile strength change rate.

[0098] In this embodiment, the test and calculation methods of the tensile strength of the obtained preset experimental double-layer polyolefin heat shrinkable tubing before and after oxidation are existing technologies that can be implemented by implementers according to national standards and will not be described in detail here. The preset tensile strength change rate set in this embodiment should also be selected according to the selected test method, but generally speaking, the selected preset tensile strength change rate should not be greater than 0.15.

[0099] Specifically, in step S4, if the actual tensile strength change rate is greater than the preset tensile strength change rate, the correction coefficient for the next preparation cycle is obtained based on the calculated actual tensile strength change rate and the preset tensile strength change rate;

[0100] Wherein, K=σs / σc×100%, K is the correction coefficient of the next preparation cycle, σs is the actual tensile strength change rate, and σc is the preset tensile strength change rate.

[0101] That is, when σs≤σc, it means that the oxidation resistance of the preset experimental double-layer polyolefin heat shrinkable tubing prepared under the current first mass ratio has met the oxidation resistance required for formal production and preparation, that is, the actual added mass of the α-olefin copolymer and the α-olefin copolymer in the composite elastomer added at this time can meet the production requirements, and no adjustment or correction is required, so the correction coefficient K of the next preparation cycle is corrected to 1;

[0102] When σs>σc, it means that the oxidation resistance of the preset experimental double-layer polyolefin heat shrinkable tubing prepared under the current first mass ratio cannot meet the oxidation resistance required in the formal production preparation, and the oxidation resistance of the preset experimental double-layer polyolefin heat shrinkable tubing prepared is weak, that is, the actual added mass of the α-olefin copolymer and the α-olefin copolymer in the composite elastomer added at this time is less than the normal required addition amount, and the actual proportion of the α-olefin copolymer is small. The actual proportion of the α-olefin copolymer as a molecule in the first mass ratio M1 should be increased, that is, the actual first mass ratio M1s should be calculated according to the correction coefficient K of the next preparation cycle obtained by calculation. In order to avoid the change of the actual first mass ratio M1s, which leads to the increase of its proportion and affects other properties of the prepared double-layer polyolefin heat shrinkable tubing, the second mass ratio M2' and the third mass ratio M3' or M3" after correction are calculated and adjusted according to the correction coefficient K of the next preparation cycle obtained by calculation, and the actual second mass ratio M2s and the actual third mass ratio M2s corresponding to the actual first mass ratio M1s are obtained.

[0103] Specifically, in step S5, the actual first mass ratio, the actual second mass ratio and the actual third mass ratio are calculated according to the correction coefficient of the next preparation cycle obtained to prepare the desired target double-layer polyolefin heat shrinkable tubing;

[0104] Among them, M1s=M1×K, M2s=M2'×K, M3s=M3'×K or M3s=M3"×K, M1s is the actual first mass ratio, M2s is the actual second mass ratio, and M3s is the actual third mass ratio.

[0105] Similarly, the present embodiment can also obtain the tensile strength of the preset experimental double-layer polyolefin heat shrinkable tubing in the room temperature environment and the tensile strength in the high temperature environment obtained in the first preparation cycle by calculation, and according to the obtained tensile strength of the preset experimental double-layer polyolefin heat shrinkable tubing in the room temperature environment and the tensile strength in the high temperature environment, calculate and obtain the actual tensile strength change rate of the preset experimental double-layer polyolefin heat shrinkable tubing in the high temperature environment, so as to detect, compare and adjust its high temperature resistance performance, which will not be repeated here.

[0106] Please continue to read Figure 5 As shown, it is a schematic diagram of the structure of the double-layer polyolefin heat shrinkable sleeve of this embodiment, which includes a heat shrinkable outer layer 1 and a hot melt adhesive inner layer 2;

[0107] Specifically, the present embodiment provides a double-layer polyolefin heat shrinkable tube prepared based on the above-mentioned preparation method of the double-layer polyolefin heat shrinkable tube, comprising a heat shrinkable outer layer 1 and a hot melt adhesive inner layer 2.

[0108] The heat shrinkable outer layer 1 is prepared by mixing alpha olefin copolymer, composite elastomer, lubricant and colorant;

[0109] The hot melt adhesive inner layer 2 is prepared by mixing alpha olefin copolymer, composite elastomer, hot melt adhesive and tackifying resin.

[0110] In this embodiment, the α-olefin copolymer used should also be selected according to the antioxidant properties of the finished double-layer polyolefin heat shrink tubing required in the specific application. For example, a lighter molecular weight ethylene-propylene copolymer can be selected as the added α-olefin copolymer, so that the finished product has excellent anti-aging properties while having good chemical stability and good flexibility and impact resistance, making it more suitable for outdoor use.

[0111] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

[0112] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a double-layer polyolefin heat shrinkable tubing, characterized in that: include, Step S1, in a first preparation cycle, a first mixed stock solution is prepared by mixing an alpha olefin copolymer and a composite elastomer in a first mass ratio; Step S2, mixing a lubricant and a colorant with the first mixed stock solution to obtain a second mixed stock solution, and using the obtained second mixed stock solution to prepare a heat shrinkable outer layer masterbatch, wherein the mass ratio of the colorant to the α-olefin copolymer is a second mass ratio; The hot melt adhesive and the tackifying resin are mixed with the first mixed stock solution to obtain a third mixed stock solution, and a hot melt adhesive inner layer masterbatch is prepared using the third mixed stock solution, wherein the mass ratio of the tackifying resin to the α-olefin copolymer is a third mass ratio; Step S3, obtaining the actual color value of the obtained heat shrinkable outer layer masterbatch, comparing and determining the actual color value of the heat shrinkable outer layer masterbatch using the preset standard color value and the preset standard color value fluctuation difference, and adjusting and correcting the second mass ratio according to the determination result; Obtaining the actual viscosity of the third mixture stock solution, comparing and determining the actual viscosity of the third mixture stock solution using the preset standard viscosity and the preset standard viscosity fluctuation difference, and adjusting and correcting the third mass ratio according to the determination result; Step S4, using the obtained heat shrinkable outer layer masterbatch and the obtained hot melt adhesive inner layer masterbatch to prepare a preset experimental double-layer polyolefin heat shrinkable sleeve, detecting and obtaining the actual tensile strength change rate of the obtained preset experimental double-layer polyolefin heat shrinkable sleeve, using the preset tensile strength change rate to compare and determine the actual tensile strength change rate, and obtaining and calculating the correction coefficient for the next preparation cycle according to the determination result; Step S5, in the next preparation cycle, the correction coefficient of the next preparation cycle, the first mass ratio, the corrected second mass ratio and the corrected third mass ratio are used to calculate to obtain the actual first mass ratio, the actual second mass ratio and the actual third mass ratio, and the actual first mass ratio, the actual second mass ratio and the actual third mass ratio are used to prepare the desired target double-layer polyolefin heat shrinkable tubing; In the step S4, the tensile strength before oxidation and the tensile strength after oxidation of the preset experimental double-layer polyolefin heat shrinkable tube prepared in the first preparation cycle are respectively calculated and obtained, and the actual tensile strength change rate of the preset experimental double-layer polyolefin heat shrinkable tube is calculated based on the obtained tensile strength before oxidation and the tensile strength after oxidation, Among them, σs=(σ1-σ2) / σ1, σs is the actual tensile strength change rate, σ1 is the tensile strength before oxidation, and σ2 is the tensile strength after oxidation.

2. The method for preparing a double-layer polyolefin heat shrinkable tubing according to claim 1, characterized in that: In the step S3, the preset standard color value and the preset standard color value fluctuation difference are set, and the actual color determination interval is calculated and obtained according to the preset standard color value and the preset standard color value fluctuation difference; In step S3, the actual color values ​​of several heat-shrinkable outer layer masterbatches are obtained and their average color value is calculated as the judgment color value, and the judgment color value is compared with the actual color judgment interval. If the determined color value is within the actual color determination interval, directly taking the current second mass ratio as the corrected second mass ratio and continuing to execute; Where, Fp= , Fp is the determined color value, xi is the actual color value of the i-th heat-shrinkable outer layer masterbatch, and n is the number of actual color values ​​of the heat-shrinkable outer layer masterbatch obtained.

3. The method for preparing a double-layer polyolefin heat shrinkable tubing according to claim 2, characterized in that: In the step S3, if the determined color value is not within the actual color determination interval, the current second mass ratio is adjusted and corrected according to the determined color value and the preset standard color value; Wherein, M2'=M2×[1-(Fp-Fb) / Fb], M2' is the corrected second mass ratio, M2 is the current second mass ratio, Fp is the determined color value, and Fb is the preset standard color value.

4. The method for preparing a double-layer polyolefin heat shrinkable tubing according to claim 3, characterized in that: In step S3, the preset standard viscosity and the preset standard viscosity fluctuation difference are further provided, and the maximum preset viscosity and the minimum preset viscosity are calculated according to the preset standard viscosity and the preset standard viscosity fluctuation difference, and the actual viscosity of the third mixture stock solution is compared with the maximum preset viscosity and the minimum preset viscosity, respectively. If the actual viscosity is greater than or equal to the minimum preset viscosity and less than or equal to the maximum preset viscosity, directly taking the current third mass ratio as the corrected third mass ratio and continuing to execute; Among them, η1=ηc-Δη, η2=ηc+Δη, η1 is the minimum preset viscosity, η2 is the maximum preset viscosity, ηc is the preset standard viscosity, and Δη is the preset standard viscosity fluctuation difference.

5. The method for preparing a double-layer polyolefin heat shrinkable tubing according to claim 4, characterized in that: In the step S3, if the actual viscosity is less than the minimum preset viscosity, the increased third mass ratio is obtained by calculating based on the actual viscosity and the preset standard viscosity as the corrected third mass ratio; If the actual viscosity is greater than the maximum preset viscosity, a reduced third mass ratio is obtained by calculation based on the actual viscosity and the preset standard viscosity as the corrected third mass ratio; Among them, M3'=M3+M3×(ηc-ηs) / ηc, M3''=M3-M3×(ηs-ηc) / ηc, M3' is the third mass ratio after increasing, M3'' is the third mass ratio after decreasing, M3 is the current third mass ratio, and ηs is the actual viscosity.

6. The method for preparing a double-layer polyolefin heat shrinkable tubing according to claim 5, characterized in that: In step S4, the preset tensile strength change rate is set, and the actual tensile strength change rate obtained is compared with the preset tensile strength change rate. If the actual tensile strength change rate is less than or equal to the preset tensile strength change rate, the correction coefficient of the next preparation cycle is corrected to 1; If the actual tensile strength change rate is greater than the preset tensile strength change rate, a correction coefficient for the next preparation cycle is calculated according to the actual tensile strength change rate and the preset tensile strength change rate.

7. The method for preparing a double-layer polyolefin heat shrinkable tube according to claim 6, characterized in that: In step S4, if the actual tensile strength change rate is greater than the preset tensile strength change rate, a correction coefficient for the next preparation cycle is obtained by calculating the calculated actual tensile strength change rate and the preset tensile strength change rate; Wherein, K=σs / σc×100%, K is the correction coefficient of the next preparation cycle, σs is the actual tensile strength change rate, and σc is the preset tensile strength change rate.

8. The method for preparing a double-layer polyolefin heat shrinkable tubing according to claim 7, characterized in that: In the step S5, the actual first mass ratio, the actual second mass ratio and the actual third mass ratio are calculated according to the obtained correction coefficient of the next preparation cycle to prepare the desired target double-layer polyolefin heat shrinkable tubing; Among them, M1s=M1×K, M2s=M2'×K, M3s=M3'×K or M3s=M3''×K, M1s is the actual first mass ratio, M2s is the actual second mass ratio, M3s is the actual third mass ratio, and M1 is the current first mass ratio.

9. A double-layer polyolefin heat shrinkable tube prepared by the method for preparing a double-layer polyolefin heat shrinkable tube according to any one of claims 1 to 8, characterized in that: Including heat shrink outer layer and hot melt adhesive inner layer, The heat shrinkable outer layer is prepared by mixing alpha olefin copolymer, composite elastomer, lubricant and colorant; The hot melt adhesive inner layer is prepared by mixing alpha olefin copolymer, composite elastomer, hot melt adhesive and tackifying resin.

Images