CN116690963A - Preparation method of heat shrinkage tube - Google Patents
Preparation method of heat shrinkage tube Download PDFInfo
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- CN116690963A CN116690963A CN202210182060.4A CN202210182060A CN116690963A CN 116690963 A CN116690963 A CN 116690963A CN 202210182060 A CN202210182060 A CN 202210182060A CN 116690963 A CN116690963 A CN 116690963A
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- 238000002360 preparation method Methods 0.000 title claims abstract description 23
- 229920001169 thermoplastic Polymers 0.000 claims abstract description 72
- 239000004416 thermosoftening plastic Substances 0.000 claims abstract description 70
- 238000001816 cooling Methods 0.000 claims abstract description 28
- 238000010438 heat treatment Methods 0.000 claims abstract description 9
- 230000008859 change Effects 0.000 claims description 34
- 239000000463 material Substances 0.000 claims description 30
- 238000000034 method Methods 0.000 claims description 29
- 238000004519 manufacturing process Methods 0.000 claims description 22
- 230000004323 axial length Effects 0.000 claims description 21
- 239000012530 fluid Substances 0.000 claims description 9
- 238000000465 moulding Methods 0.000 claims description 8
- 239000007788 liquid Substances 0.000 claims description 6
- 230000001050 lubricating effect Effects 0.000 claims description 5
- 229920000728 polyester Polymers 0.000 claims description 5
- 229920002313 fluoropolymer Polymers 0.000 claims description 4
- 125000003118 aryl group Chemical group 0.000 claims description 3
- 239000011261 inert gas Substances 0.000 claims description 3
- 229920001643 poly(ether ketone) Polymers 0.000 claims description 3
- 229920000098 polyolefin Polymers 0.000 claims description 3
- 230000008569 process Effects 0.000 description 19
- 238000004904 shortening Methods 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 7
- 238000001125 extrusion Methods 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- 230000008602 contraction Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 230000009477 glass transition Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 239000002861 polymer material Substances 0.000 description 2
- 239000012815 thermoplastic material Substances 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C61/00—Shaping by liberation of internal stresses; Making preforms having internal stresses; Apparatus therefor
- B29C61/02—Thermal shrinking
- B29C61/025—Thermal shrinking for the production of hollow or tubular articles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C61/00—Shaping by liberation of internal stresses; Making preforms having internal stresses; Apparatus therefor
- B29C61/02—Thermal shrinking
Abstract
The invention relates to a preparation method of a heat shrinkage tube, which comprises the following steps: heating the thermoplastic pipe to a high-elastic state for expansion, and cooling and forming to obtain a heat shrinkage pipe; the controls a and b satisfy the following conditions: ab >1, and controlling the pushed speed v' and the pulled speed v of the thermoplastic pipe during the expansion to meet the following conditions: Δs=v'/v-1>1% such that the resulting heat shrink tube is radially expanded and axially contracted compared to the thermoplastic tubing; wherein a is the ratio of the inner diameter of the heat shrinkage tube after expansion to the inner diameter of the thermoplastic tube before expansion, b is the ratio of the wall thickness of the heat shrinkage tube after expansion to the wall thickness of the thermoplastic tube before expansion, and deltas is the traction speed difference rate during expansion. The preparation method provides a brand new preparation method for the heat-shrinkable tube which can be axially stretched after being heated in use, and the prepared heat-shrinkable tube has wide application prospect.
Description
Technical Field
The invention relates to the technical field of medical equipment, in particular to a preparation method of a heat shrinkage tube.
Background
The thermoplastic material used for the heat shrink tube is in a glass state at room temperature, becomes a high-elastic state after being heated, has the functions of high-temperature shrinkage, softness, flame retardance, insulation and corrosion resistance, is coated on parts needing protection such as wires and cables, electronic parts, assembled medical accessories and the like, and has wide application in the fields of industry, electronics, medical treatment and the like.
In the production process of the traditional heat-shrinkable tube, the thermoplastic tube is heated to a high-elastic state, and is subjected to radial expansion by applying a load, and is rapidly cooled in the state of maintaining the radial expansion, so that the thermoplastic tube enters a glassy state. When the heat-shrinkable tube is used, the heat-shrinkable tube is heated to be in a high-elastic state, no load is applied at the moment, the heat-shrinkable tube is radially shrunk, and the heat-shrinkable tube is tightly covered on a part to be protected through the radial shrinkage of the heat-shrinkable tube.
However, during application, the heat shrink tube will not only shrink radially after being heated, but in most cases will also change length in the axial direction, for example shrink in the axial direction will be shorter. Heat shrink tubing that shrinks to shorten after being heated can cause various problems. For example, if the heat shrinkage tube is wrinkled in the process of shrinking and shortening, defects such as surface relief and bulge can be caused; the folds of the heat shrinkage tube can even cause folds on the surface of the material covered by the heat shrinkage tube, so that the flatness of the surface of the covered material is reduced, and the reworking difficulty is increased. In addition, the part originally covered with the heat shrink tube may be exposed to the heat source due to the shortening of the shrinkage of the heat shrink tube, and the exposed part may be melted and deformed. In order to avoid the defect caused by shrinkage and shortening of the heat shrinkage tube after heating, the heat shrinkage tube is sometimes stretched while heating so as to prevent the shrinkage and shortening of the axial length of the heat shrinkage tube after heating. However, this method tends to stretch the heat shrinkable tube and even damage the material of the part covered by the heat shrinkable tube.
Disclosure of Invention
Based on this, it is necessary to provide a method for producing a heat shrinkable tube which can be axially elongated after being heated at the time of use.
The invention is realized by the following technical scheme.
The invention provides a preparation method of a heat shrinkage tube, which comprises the following steps:
heating the thermoplastic pipe to a high-elastic state for expansion, and cooling and forming to obtain a heat shrinkage pipe;
the controls a and b satisfy the following conditions: ab >1, and controlling the pushed speed v' and the pulled speed v of the thermoplastic pipe during the expansion to meet the following conditions: Δs=v'/v-1>1% such that the resulting heat shrink tube is radially expanded and axially contracted compared to the thermoplastic tubing;
wherein a is the ratio of the inner diameter of the heat shrinkage tube after expansion to the inner diameter of the thermoplastic tube before expansion, b is the ratio of the wall thickness of the heat shrinkage tube after expansion to the wall thickness of the thermoplastic tube before expansion, and deltas is the traction speed difference rate during expansion.
In some of these embodiments, the controls a and b satisfy the following conditions:
wherein d is the original inner diameter of the thermoplastic pipe before expansion, and w is the original wall thickness of the thermoplastic pipe before expansion.
In some of these embodiments, the expanding is performed in a mold;
the die is an inner supporting die, and the material of the thermoplastic pipe, the outer diameter of the inner supporting die and the inner diameter of the thermoplastic pipe are controlled so as to control a and b to meet the conditions;
or the die is an outer support die, and the material of the thermoplastic pipe, the inner diameter of the outer support die and the outer diameter of the thermoplastic pipe are controlled so as to control a and b to meet the conditions.
In some of these embodiments, the ratio a of the inner diameter of the heat shrink tubing after expansion to the inner diameter of the thermoplastic tubing prior to expansion is greater than or equal to 1.2; and/or the number of the groups of groups,
when the material of the heat shrinkage tube is selected from aromatic polyether ketone, a is less than or equal to 1.5; when the material of the heat shrinkage tube is selected from fluoroplastic, a is less than or equal to 4.0; when the material of the heat shrinkage tube is selected from polyester, a is less than or equal to 7.5; when the material of the heat shrinkage tube is selected from polyolefin, a is less than or equal to 10.
In some of these embodiments, a fluid is filled between the thermoplastic tubing and the mold upon the expanding, the fluid being an inert gas or a lubricating liquid.
In some of these embodiments, the fluidThe kinematic viscosity at 40 ℃ is more than or equal to 17mm 2 /s。
In some of these embodiments, the traction speed differential rate Δs experienced at the expansion is controlled to be >4.5%.
In some of these embodiments, the traction speed differential rate Δs experienced at the expansion is controlled to be >10%.
In some of these embodiments, controlling the traction speed difference rate Δs that is experienced at the expansion to be less than or equal to e/(e+1); wherein,
d is the inner diameter of the thermoplastic pipe before expansion, w is the wall thickness of the thermoplastic pipe before expansion, and e is the axial length change rate of the heat shrinkage pipe before and after shrinkage in a use state.
In some embodiments, the cooling rate of the cooling profile is 60 ℃/s or less.
In some of these embodiments, the cooling rate of the cooling profile is <3 ℃/s.
According to the preparation method of the heat-shrinkable tube, the ratio a of the inner diameter of the heat-shrinkable tube to the inner diameter of the thermoplastic tube and the ratio b of the wall thickness of the heat-shrinkable tube to the wall thickness of the thermoplastic tube are controlled to meet specific conditions, and meanwhile, the traction speed difference rate delta s during expansion is controlled to meet specific conditions, so that the prepared heat-shrinkable tube is radially expanded and axially contracted compared with the thermoplastic tube. Thus, after the heat shrinkage tube is heated again and fully shrunk, the heat shrinkage tube can realize axial elongation while being radially shrunk. The preparation method provides a brand new preparation method for the heat-shrinkable tube which can be axially stretched after being heated in use, and the prepared heat-shrinkable tube has wide application prospect.
Detailed Description
The present invention will be described more fully hereinafter in order to facilitate an understanding of the present invention, and preferred embodiments of the present invention are set forth. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It should be understood that these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
Aiming at the technical problems of the heat-shrinkable tube which is axially contracted and shortened after being heated in the application process, the traditional solution is to stretch the heat-shrinkable tube while heating so as to prevent the axial length of the heat-shrinkable tube from being contracted and shortened after being heated. However, this method tends to stretch the heat shrinkable tube and even damage the material of the part covered by the heat shrinkable tube. This method is only adequate for operators with high skill, and has extremely high demands on the operators. Based on a great deal of research, the technical personnel of the invention deeply analyze the preparation principle of the heat shrinkage tube, and provide a preparation method of the heat shrinkage tube which can axially stretch after being heated during use.
The traditional preparation method of the heat shrinkage tube is that a thermoplastic tube is heated to a temperature lower than the melting point of the thermoplastic polymer tube and higher than the glass transition temperature of the thermoplastic polymer tube to form a high-elastic state, a load is applied to the tube to enable the tube to radially expand, and the tube is cooled to a temperature lower than the glass transition temperature of the tube in the radially expanded state and enters the glass state. So far, the heat shrinkage tube is manufactured. The skilled person analyses that the essence of the method of manufacturing a heat shrink tube is to store the radially expanding stress applied to the tube in its polymer chain. And the tube is shrunk again by heat, because this stress is released when the tube is heated again, so that radial shrinkage of the tube occurs. In fact, the heat shrink tubing will not only shrink radially after being heated, but will in most cases also change length in the axial direction, including shortening or lengthening the axial shrinkage. Compared with a heat-shrinkable tube which is axially contracted and shortened after being heated in use, the heat-shrinkable tube which is axially stretched after being heated in use is a more economical and more convenient choice. The technical staff of the invention provides an innovation of a preparation process, if radial expansion and axial shortening of the pipe can be realized through the preparation process of the heat shrinkage pipe according to a similar principle, the stress of radial expansion and the stress of axial extrusion can be stored in a polymer chain of the heat shrinkage pipe at the same time. These stresses will be relieved when the tubing is heated again, causing simultaneous radial contraction and axial elongation of the tubing.
In order to realize the axial shortening of the pipe by the manufacturing process of the heat shrinkage pipe, the proper pipe size needs to be designed first. The length of the pipe before the heat shrinkage pipe is manufactured (namely before expansion) is set to be L, the inner diameter is d, the wall thickness is w, and the units are the same. If the inner diameter expansion ratio during expansion is a and the wall thickness thinning ratio is b, the tube having the original inner diameter d, the original wall thickness w and the original length L is expanded to become a heat shrinkable tube having the inner diameter ad, the wall thickness bw and the length L'. In other words, the inner diameter expansion ratio is the ratio of the inner diameter of the heat shrinkage tube to the inner diameter of the thermoplastic tube; the wall thickness thinning ratio is the ratio of the wall thickness of the heat shrinkage tube to the wall thickness of the thermoplastic tube.
When in use, the heat shrinkage tube is shrunk after being heated, and the heat shrinkage tube is restored to the heat shrinkage tube with the length of L, the inner diameter of d and the wall thickness of w, namely the state of the heat shrinkage tube is the same as that before expansion. The lengths, inner diameters and wall thicknesses of the tubes in the three states before expansion, after expansion and after contraction are shown in table 1 below. The heat pipe is manufactured by the heat pipe and the original pipe before the heat pipe is manufactured by the heat pipe before the heat pipe is expanded, the pipe is formed after the heat pipe is manufactured after the heat pipe is expanded, and the pipe is manufactured after the heat pipe is contracted.
TABLE 1
| Status of | Length of | Inner diameter of | Wall thickness |
| Before expansion | L | d | w |
| After expansion | L’ | ad | bw |
| After shrinkage | L | d | w |
After expansion, the molecular chain segments of the pipe material move, and the pipe shows great deformation in a dimension of a certain size, but the whole expansion process does not involve the processes of crosslinking, polymerization and the like of the pipe material, which affect the density of the high polymer material of the pipe, and in addition, the length, the inner diameter and the wall thickness in the table 1 are parameters in a room temperature state, and the process of temperature on the density of the high polymer material does not exist. Thus, the density change of the tubing material before and after expansion is small and negligible in the system. So, according to mass conservation, it can be seen that:
[(d+2w) 2 -d 2 ]·L＝[(ad+2bw) 2 -(ad) 2 )]·L’ (1)
the axial length change rate of the heat shrinkage tube before and after expansion is the ratio of the length L' after expansion to the length L before expansion minus 1. If the manufacturing process of the heat shrinkage tube is used for realizing the axial shortening of the tube, namely: the axial length change rate of the heat shrinkage tube before and after expansion is less than 0. In other words, it is necessary to: the length change rate of the axial direction of the heat shrinkage tube before and after use is more than 0, wherein the length change rate of the axial direction of the heat shrinkage tube before and after use is the ratio of the length L of the heat shrinkage tube after shrinkage to the length L' of the heat shrinkage tube before use (i.e. after expansion) minus 1. If the length change rate of the heat shrinkage tube in the axial direction before and after use is e
e＝L/L’-1 (2)
From the above formula (1) and formula (2), the following formula (3) can be seen:
if the tubular product is axially elongated when the heat shrink tube is heated, e >0 is a necessary condition. The condition that e >0 is the following formula (4):
the original inner diameter d and the original wall thickness w of the pipe before expansion are positive numbers, namely w/d is more than 0; and because the wall thickness thinning proportion b is less than 1, the necessary conditions for realizing the length change rate e >0 of the heat shrinkage tube in the axial direction before and after use are as follows: ab >1. I.e. the product of the inner diameter expansion ratio a and the wall thickness thinning ratio b is controlled to be more than 1.
In order to ensure that the heat shrinkable tube can be easily sleeved outside other objects when in use, a is generally more than or equal to 1.2. Based on the above analysis, a is larger as the inner diameter or outer diameter of the die used for expansion is larger. However, according to the mechanical properties of the thermoplastic material of the pipe, there is an upper limit on the value of a: for example, the aromatic polyether ketone heat shrink tube has a value of generally equal to or less than 1.5, the fluoroplastic heat shrink tube has a value of generally equal to or less than 4.0, the polyester heat shrink tube has a value of generally equal to or less than 7.5, and the polyolefin heat shrink tube has a value of generally equal to or less than 10.
On the basis of the material determination of the thermoplastic pipe, the upper limit of the value of the inner diameter expansion ratio a is determined. Within this upper limit, a mold of an appropriate size is selected. In the case that the inner diameter and the outer diameter of the thermoplastic pipe are determined, the inner diameter expansion ratio a can be determined by the die size control of the heat shrinkage pipe manufacturing process, because the heat shrinkage pipe manufacturing process usually uses an inner support die with a fixed outer diameter to expand the pipe from the inside so as to fix the inner diameter of the expanded pipe; or wrapping the outer part of the pipe by using an outer support die with a fixed inner diameter so as to fix the outer diameter of the expanded pipe.
For the inner support die, the outer diameter of the inner support die is larger than the inner diameter of the thermoplastic pipe, the outer diameter of the inner support die is the inner diameter of the thermoplastic pipe after expansion, and the ratio of the outer diameter of the inner support die to the inner diameter of the thermoplastic pipe is the preset inner diameter expansion ratio of the inner support die.
For the outer support die, the inner diameter of the outer support die is larger than the outer diameter of the thermoplastic pipe, the inner diameter of the outer support die is the outer diameter of the thermoplastic pipe after expansion, and the preset inner diameter expansion ratio of the outer support die can be accurately estimated through the inner diameter of the outer support die, the inner diameter and the wall thickness of the thermoplastic pipe.
In summary, the inner diameter expansion ratio a is determined by the outer diameter of the inner support die and the inner diameter of the thermoplastic pipe, or by the inner diameter of the outer support die and the inner diameter and wall thickness of the thermoplastic pipe.
While the wall thickness reduction ratio b can generally be determined by the common control of the inner diameter expansion ratio a and the material of the thermoplastic tubing. Generally, the larger the upper limit value of a of the heat shrinkable tube material or the larger a obtained at the time of expansion, the smaller b. For example, the upper limit value of a of the fluoroplastic heat shrink tube is 4.0, and b is generally in the range of 0.25-0.85; the upper limit value of a of the polyester heat shrink tube is 7.5, and b is generally in the range of 0.02 to 0.2. Therefore, by adopting a mould with proper size and selecting the materials of the thermoplastic pipe, the manufacturing process of the heat shrinkage pipe can theoretically realize the axial shortening of the pipe, and the heat shrinkage pipe with the axial length change rate of more than 0% after complete shrinkage is manufactured.
In the case where the material of the thermoplastic pipe is determined, the mold is an inner support mold, and the material of the thermoplastic pipe, the outer diameter of the inner support mold, and the inner diameter of the thermoplastic pipe may be controlled to control a and b to satisfy the above conditions.
In the case of determining the material of the thermoplastic pipe, the mold is an outer support mold, and the material of the thermoplastic pipe, the inner diameter of the outer support mold, and the inner diameter and wall thickness of the thermoplastic pipe are controlled so that a and b are controlled to satisfy the above conditions.
Furthermore, in order to realize the axial shortening of the pipe by the manufacturing process of the heat shrinkage pipe, the manufacturing process needs to be controlled in addition to the axial shortening of the pipe in the manufacturing process caused by the selection of the mold with proper size and the material of the thermoplastic pipe, and the axial shortening of the pipe is mainly avoided by the axial stretching induced by the process.
On the basis of the method, in combination with the actual situation, in order to carry out mass production of the heat shrinkage tube in a limited space, the tube and the die inevitably perform relative movement during expansion. In the moving process, the pipe is axially stretched by axial traction force and the like, so that the tendency of axial shortening of the pipe is counteracted. To avoid such axial stretching introduced by the process, the push speed v' of the thermoplastic tubing can be controlled to be greater than the pull speed v. If the traction speed difference rate deltas is used to quantify the axial stretching degree to which the pipe is subjected, wherein the traction speed difference rate deltas=v '/v-1, it is verified by experiments that the pushed speed v' and the pulled speed v of the thermoplastic pipe at the time of expansion need to be controlled to satisfy the following conditions: Δs=v'/v-1>1%.
Where Δs is the traction speed difference rate.
According to the preparation method of the heat-shrinkable tube, the ratio a of the inner diameter of the heat-shrinkable tube to the inner diameter of the thermoplastic tube and the ratio b of the wall thickness of the heat-shrinkable tube to the wall thickness of the thermoplastic tube are controlled to meet specific conditions, and meanwhile, the traction speed difference rate delta s during expansion is controlled to meet specific conditions, so that the prepared heat-shrinkable tube is radially expanded and axially contracted compared with the thermoplastic tube. Thus, after the heat shrinkage tube is heated again and fully shrunk, the heat shrinkage tube can realize axial elongation while being radially shrunk. The preparation method provides a brand new preparation method for the heat-shrinkable tube which can be axially stretched after being heated in use, and the prepared heat-shrinkable tube has wide application prospect.
In order to avoid deviation between theory and practice, the axial length change rate of the heat-shrinkable tube after complete shrinkage is ensured as far as possible, that is, the axial length change rate e of the heat-shrinkable tube before and after shrinkage is more than 0 in the use state, the theoretical value of e can be specified to be more than 5%. According to the formula (1), the pipe size design of the heat shrinkable pipe needs to control a and b to meet the following conditions:
wherein, the original inner diameter d and the original wall thickness w of the pipe can be determined by the previous working procedure before the heat-shrinkable tube is manufactured. Therefore, preferably, the original inner diameter d and the original wall thickness w of the pipe are combined, and a mold with proper size and the material selection of the thermoplastic pipe are adopted, so that the control a and the control b meet the formula (5), and the length change rate e of the prepared heat shrinkage pipe in the axial direction of the heat shrinkage pipe before and after shrinkage in the use state can be improved. Specifically, before the finished heat shrinkage tube is manufactured, the value of a, b, d, w is obtained through the size of the thermoplastic tube and the design of materials and the selection of an expansion die, and the theoretical value of e is calculated in advance according to a formula (3). Considering that there may be a deviation between the theoretical value and the actual value, the e value needs to be left with a margin, so the combination selection of a, b, d, w values needs to satisfy the formula (5). In the actual manufacturing process, the actual value and the theoretical value of e are more approximate to each other as much as possible through the regulation and control of the technological parameters.
It can be understood that the pipe needs to be heated in the preparation process of the heat-shrinkable pipe, so that the selected mold is a mold with a heating function, which is called a heating mold. During expansion, the tubing and the die will inevitably undergo relative movement. During this movement, the friction between the tube and the heated die also causes the tube to be axially stretched, counteracting its own tendency to axially shorten. To avoid such axial stretching introduced by the process, lubrication between the tubing and the heated die may be used to reduce the friction. Further, the fluid is an inert gas or a lubricating liquid; further, the lubricating liquid therein is preferably a high-temperature resistant lubricating liquid.
At present, no method for quantifying friction is directly found, but the friction can be indirectly quantified by using the kinematic viscosity of fluid (fluid refers to the sum of gas and liquid) between a pipe and a die. Preferably, the kinematic viscosity of the fluid between the pipe and the die is controlled within a range of 17mm or more 2 /s(40℃)。
In some embodiments, controlling the traction speed difference rate deltas to be more than 4.5%, more preferably more than 10%, can enable the manufacturing process of the heat-shrinkable tube to better realize the axial shortening of the tube after expansion, and can obtain the heat-shrinkable tube with the axial length change rate of more than 0% after complete shrinkage.
Further, there is an upper limit to Δs, otherwise in the case where the pushed speed v' of the pipe is too fast but the pulled speed v is too slow, the pipe may be piled up at the die, and the continuity of production is easily broken, which is called "piling up. In order to avoid the occurrence of "piling", it is required that the amount of accumulation of the pipe caused by the difference in pushing and pulling speeds in the whole expanding process cannot exceed the amount of shortening of the pipe itself, i.e., the following conditions are satisfied:
v't-vt≤L-L’ (6)
where t is the total time of the tubing expansion process, i.e., L/v. Substituting the relation of t=l/v into the above formula (6) makes it possible to obtain: v 'L/v-L is less than or equal to L-L';
namely: v '/v-1 is less than or equal to 1-L'/L.
According to the foregoing formula (2) e=l/L' -1, the following formula is obtained:
Δs＝v'/v-1≤e/(e+1) (7)
according to the foregoing formula (3), wherein:
in some embodiments, the cooling rate of the cooling profile is less than or equal to 60 ℃/s, such as 60 ℃/s, 59 ℃/s, 58 ℃/s, 57 ℃/s, 56 ℃/s, 55 ℃/s, 50 ℃/s, 40 ℃/s, 30 ℃/s, 20 ℃/s, 18 ℃/s, 16 ℃/s, 14 ℃/s, 12 ℃/s, 10 ℃/s, 8 ℃/s, 6 ℃/s, 5 ℃/s, 4.5 ℃/s, 4 ℃/s, 3 ℃/s, 2 ℃/s, 1 ℃/s. Further, as an optional condition for promoting the heat shrinkage tube to store the axial extrusion stress, so that the preparation process of the heat shrinkage tube achieves a better axial shrinkage effect, the cooling speed dT can be slowly cooled at a speed of <3 ℃/s after the heat shrinkage tube is formed, so that the too fast cooling is prevented, the axial extrusion stress is not well stored by the heat shrinkage tube, and the axial length change rate of the heat shrinkage tube is prevented from being lower than an expected level after the heat shrinkage tube is completely shrunk.
In order to make the objects, technical solutions and advantages of the present invention more concise, the present invention will be described in the following specific examples, but the present invention is by no means limited to these examples. The following examples are only preferred embodiments of the present invention, which can be used to describe the present invention, and should not be construed as limiting the scope of the invention. It should be noted that any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
In order to better illustrate the present invention, the following description of the present invention will be given with reference to examples. The following are specific examples.
The preparation of the heat shrinkage pipe in the following comparative examples and examples is performed in an outer support mold, and the preset inner diameter expansion ratio a of the outer support mold can be accurately estimated by the inner diameter of the outer support mold, the inner diameter and the wall thickness of the thermoplastic pipe.
Comparative example 1:
using an outer support die with an inner diameter of 8.5mm, a polyester pipe with an original inner diameter of 5.08mm and an original wall thickness of 0.32mm was expanded to a heat shrink pipe with an inner diameter of 8.35mm (a=1.64) and a wall thickness of 0.05mm (b=0.16).
Wherein the expansion temperature used is 130 ℃, the traction speed difference rate delta s is 0.0%, and the cooling speed dT of cooling molding after expansion is 2.4 ℃/s.
The length change rate of the prepared heat-shrinkable tube in the axial direction after being heated at 240 ℃ is-82.6 percent after the heat-shrinkable tube is completely shrunk.
Example 1:
using an outer support die with an inner diameter of 8.5mm, a fluororesin tube with an original inner diameter of 5.08mm and an original wall thickness of 0.32mm was expanded to a heat shrinkable tube with an inner diameter of 7.95mm (a=1.56) and a wall thickness of 0.23mm (b=0.72).
Wherein the expansion temperature used in the process is 180 ℃, the traction speed difference rate delta s is 1.2%, and the cooling speed dT of cooling molding after expansion is 2.4 ℃/s.
The average value of the axial length change rate of the prepared heat-shrinkable tube after being heated at the temperature of 240 ℃ is 2.3 percent.
Example 2:
example 2 is essentially the same as example 1 except that the process of example 2 uses a cooling rate dT of 56.7 ℃/s.
The length change rate of the prepared heat-shrinkable tube in the axial direction after being heated at the temperature of 240 ℃ is 0.7 percent in average value after being completely shrunk.
Example 3:
using an outer support die having an inner diameter of 5.9mm, a fluororesin tube having an original inner diameter of 3.20mm and an original wall thickness of 0.38mm was expanded to a heat shrinkable tube having an inner diameter of 5.28mm (a=1.65) and a wall thickness of 0.29mm (b=0.76).
Wherein the expansion temperature used in the process is 180 ℃, and the traction speed difference rate delta s is 6.4%; the cooling rate dT of the cooling molding after expansion was 56.7 ℃/s.
The average value of the axial length change rate of the prepared heat-shrinkable tube after being heated at the temperature of 240 ℃ is 5.2 percent.
Comparative example 2:
comparative example 2 is substantially the same as example 3 except that: the process uses a traction speed differential rate deltas of 0.2%.
The length change rate of the prepared heat-shrinkable tube in the axial direction after being heated at 240 ℃ is-1.4% in average value.
Example 4:
using an outer support die having an inner diameter of 1.3mm, a fluororesin tube having an original inner diameter of 0.39mm and an original wall thickness of 0.32mm was expanded to a heat shrinkable tube having an inner diameter of 0.79mm (a=2.03) and a wall thickness of 0.25mm (b=0.78).
Wherein the expansion temperature used in the process is 180 ℃, the traction speed difference rate delta s is 11.1%, and the cooling speed dT of cooling molding after expansion is 0.4 ℃/s.
The average value of the axial length change rate of the prepared heat-shrinkable tube after being heated at the temperature of 240 ℃ is 10.4 percent.
Example 5:
example 5 is substantially identical to example 4, except that: the process uses a traction speed differential rate deltas of 4.5%.
The average value of the axial length change rate of the prepared heat-shrinkable tube after being heated at the temperature of 240 ℃ is 3.8 percent.
Example 6:
using an outer support die having an inner diameter of 10.4mm, a fluororesin tube having an original inner diameter of 5.50mm and an original wall thickness of 0.50mm was expanded to a heat shrinkable tube having an inner diameter of 9.73mm (a=1.77) and a wall thickness of 0.31mm (b=0.62).
Wherein the expansion temperature used in the process is 180 ℃, the traction speed difference rate delta s is 1.7%, and the cooling speed dT of cooling molding after expansion is 6.0 ℃/s.
The average value of the axial length change rate of the prepared heat-shrinkable tube after being heated at 240 ℃ is 0.1%, and the maximum value in the test data is 0.4% and the minimum value is-0.8%.
Some of the parameters for each example are shown in Table 2:
wherein the theoretical value of e is (abd+b) 2 w)/(d+w)-1。
Δs=push speed of pipe/pull speed of pipe-1.
The axial length change rate average value (N) is the average value of the length change rates measured by taking 10 parallel samples. The theoretical and mean values of e are positive values, indicating that the length change is an elongation trend; negative values indicate that the length change is a shrinkage trend.
TABLE 2
From the above embodiment, by using the above preparation process, the heat-shrinkable tube which is axially elongated after complete shrinkage can be obtained, and the axial length change rate of the heat-shrinkable tube after complete shrinkage, that is, the axial length change rate e of the heat-shrinkable tube before and after use is as high as 10.4%.
The theoretical value of e of ab < 1 controlled in comparative example 1 is negative, and the average value of the heat shrinkage tube actually prepared is also negative, which indicates that the axial direction of the heat shrinkage tube prepared is shortened after the heat shrinkage tube is heated again and completely shrunk. The reason for this is that the shrinkage of the heat shrinkable tube product takes place in the axial direction after complete shrinkage, since the relation ab >1 is not satisfied.
Comparative example 2 was substantially the same as example 3, except that ab >1 was controlled, however, the traction speed difference rate Δs < 1% was controlled in comparative example 2, the theoretical value of e was positive, the average value of the heat shrinkage tube actually produced was negative, and the produced heat shrinkage tube was shortened in the axial direction after being heated again to shrink completely.
As is clear from comparison of example 1 and example 2, example 1 is beneficial to improving the axial length change rate of the prepared heat-shrinkable tube after complete shrinkage by controlling the cooling rate of cooling molding to be less than 3 ℃/s.
As is clear from examples 4 and 5, in example 4, the traction speed difference rate Deltas >4.5% is controlled as compared with example 5, which is advantageous for improving the axial length change rate of the heat shrinkable tube after complete shrinkage.
The theoretical value of e for ab >1 controlled in example 6 is positive, and the mean value of the heat shrink tube actually produced is also positive (but close to 0). The length change rate e of the heat shrinkage tube prepared in the embodiment 6 in the axial direction is smaller than that of the heat shrinkage tube prepared in other embodiments before and after the heat shrinkage tube is used. The reason for this is that the relationship described in the above formula (5) (i.e., theoretical value of e > 5%) is not satisfied, and the theoretical value of e in example 6 is 5% or less, and the actual value of e deviates from the theoretical value due to dimensional tolerance of the mold and the pipe, fluctuation of the process parameters, and the like.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. The scope of the invention is, therefore, indicated by the appended claims, and the description may be intended to interpret the contents of the claims.
Claims (11)
1. The preparation method of the heat shrinkage tube is characterized by comprising the following steps:
heating the thermoplastic pipe to a high-elastic state for expansion, and cooling and forming to obtain a heat shrinkage pipe;
the controls a and b satisfy the following conditions: ab >1, and controlling the pushed speed v' and pulled speed v of the thermoplastic pipe during the expansion to satisfy the following conditions: Δs=v'/v-1>1% such that the resulting heat shrink tube is radially expanded and axially contracted compared to the thermoplastic tubing;
wherein a is the ratio of the inner diameter of the heat shrinkage tube after expansion to the inner diameter of the thermoplastic tube before expansion, b is the ratio of the wall thickness of the heat shrinkage tube after expansion to the wall thickness of the thermoplastic tube before expansion, and deltas is the traction speed difference rate during expansion.
2. The method for manufacturing a heat shrinkable tube as defined in claim 1, wherein a and b are controlled to satisfy the following conditions:
wherein d is the inner diameter of the thermoplastic pipe before expansion, and w is the wall thickness of the thermoplastic pipe before expansion.
3. A method of producing a heat shrinkable tube according to any one of claims 1 to 2, wherein the expansion is performed in a mold;
the die is an inner supporting die, and the material of the thermoplastic pipe, the outer diameter of the inner supporting die and the inner diameter of the thermoplastic pipe are controlled so as to control a and b to meet the conditions;
or the die is an outer support die, and the material of the thermoplastic pipe, the inner diameter of the outer support die and the outer diameter of the thermoplastic pipe are controlled so as to control a and b to meet the conditions.
4. The method for producing a heat shrinkable tube according to any one of claims 1 to 2, wherein a ratio a of an inner diameter of the heat shrinkable tube after expansion to an inner diameter of the thermoplastic tube before expansion is not less than 1.2; and/or the number of the groups of groups,
when the material of the heat shrinkage tube is selected from aromatic polyether ketone, a is less than or equal to 1.5; when the material of the heat shrinkage tube is selected from fluoroplastic, a is less than or equal to 4.0; when the material of the heat shrinkage tube is selected from polyester, a is less than or equal to 7.5; when the material of the heat shrinkage tube is selected from polyolefin, a is less than or equal to 10.
5. A method of manufacturing a heat shrink tube as set forth in claim 3, wherein a fluid is filled between the thermoplastic tube and the mold during the expansion, the fluid being an inert gas or a lubricating liquid.
6. The method for preparing a heat shrinkable tube as defined in claim 5, wherein the kinematic viscosity of the fluid at 40 ℃ is more than or equal to 17mm 2 /s。
7. A method of manufacturing a heat shrink tube as set forth in claim 1, wherein a traction speed difference rate Δs received at the time of the expansion is controlled to be >4.5%.
8. The method of manufacturing a heat shrinkable tube of claim 7, wherein a drawing speed difference rate Δs received at the time of the expansion is controlled to be >10%.
9. A method for producing a heat shrinkable tube according to any one of claims 1 to 2, 5 to 8, wherein a drawing speed difference ratio Δs.ltoreq.e/(e+1) to be applied at the time of the expansion is controlled;
wherein ,
d is the inner diameter of the thermoplastic pipe before expansion, w is the wall thickness of the thermoplastic pipe before expansion, and e is the axial length change rate of the heat shrinkage pipe before and after shrinkage in a use state.
10. The method of producing a heat shrinkable tube according to any one of claims 1 to 2 and 5 to 8, wherein the cooling rate of the cooling molding is 60 ℃/s or less.
11. The method of manufacturing a heat shrink tube as set forth in claim 10, wherein the cooling rate of the cooling molding is <3 ℃/s.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210182060.4A CN116690963A (en) | 2022-02-25 | 2022-02-25 | Preparation method of heat shrinkage tube |
| PCT/CN2023/076112 WO2023160440A1 (en) | 2022-02-25 | 2023-02-15 | Preparation method for heat-shrinkable tube |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210182060.4A CN116690963A (en) | 2022-02-25 | 2022-02-25 | Preparation method of heat shrinkage tube |
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| CN116690963A true CN116690963A (en) | 2023-09-05 |
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| CN202210182060.4A Pending CN116690963A (en) | 2022-02-25 | 2022-02-25 | Preparation method of heat shrinkage tube |
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| WO (1) | WO2023160440A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04358823A (en) * | 1991-06-06 | 1992-12-11 | Sumitomo Electric Ind Ltd | Method and apparatus for manufacture of heat-shrinkable tube |
| JP2005016602A (en) * | 2003-06-25 | 2005-01-20 | Mitsui Chemicals Inc | Heat shrinkable pipe joint and pipe jointing part |
| NL2003666C2 (en) * | 2009-10-19 | 2011-04-20 | Rollepaal Holding B V | Methods and devices for manufacturing biaxially oriented tubing. |
| CN102429749A (en) * | 2011-07-27 | 2012-05-02 | 微创医疗器械(上海)有限公司 | Novel processing method for biodegradable stent |
| CN104017310B (en) * | 2014-06-20 | 2016-08-24 | 福建博大塑业新材料有限公司 | A kind of biaxially orienting polyvinyl chloride pipe and preparation method thereof |
| CN104146755B (en) * | 2014-08-28 | 2016-06-01 | 华东理工大学 | A kind of miniature sacculus of self-enhancement thin-walled and preparation method thereof |
| CN108814780A (en) * | 2015-02-16 | 2018-11-16 | 上海微创医疗器械（集团）有限公司 | Biodegradable stent and preparation method thereof |
| JP6613147B2 (en) * | 2016-01-14 | 2019-11-27 | 住友電気工業株式会社 | Heat recovery component, wire bundle, and insulated wire coating method |
| US11186753B2 (en) * | 2016-09-23 | 2021-11-30 | Exxonmobil Chemical Patents Inc. | Shrinkable thermoplastic vulcanizate and method and article |
| CN108017825A (en) * | 2017-12-27 | 2018-05-11 | 上海长园电子材料有限公司 | A kind of ultra-thin high power shrinks heat-shrinkable T bush and preparation method thereof |
| CN110370609A (en) * | 2019-06-28 | 2019-10-25 | 大连联合高分子材料有限公司 | A kind of preparation method of high convergency multiplying power high temperature resistant perfluoroethylenepropylene heat-shrinkable T bush |
| CN110625905A (en) * | 2019-10-15 | 2019-12-31 | 吕延泉 | High-temperature low-expansion-ratio online axial-orientation-reinforced toughened PVC-C pipe extrusion device and method |
| CN112759895A (en) * | 2021-01-20 | 2021-05-07 | 昶力管业(常州)有限公司 | Polyamide elastomer modified heat-shrinkable protective sleeve and preparation method thereof |
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