CN115182060A

CN115182060A - Ultra-high molecular weight polyethylene fiber and preparation method and application thereof

Info

Publication number: CN115182060A
Application number: CN202210907648.1A
Authority: CN
Inventors: 许海霞; 黄金元; 王新威; 孙勇飞; 郑晗; 王萍; 黄周雨
Original assignee: Shanghai Research Institute of Chemical Industry SRICI
Current assignee: Shanghai Research Institute of Chemical Industry SRICI
Priority date: 2022-07-29
Filing date: 2022-07-29
Publication date: 2022-10-14
Anticipated expiration: 2042-07-29
Also published as: CN115182060B

Abstract

The invention relates to an ultra-high molecular weight polyethylene fiber and a preparation method and application thereof. Mixing the ultrahigh molecular weight polyethylene resin powder, a solvent and an auxiliary agent, and swelling, dissolving, spinning and stretching to obtain a dry semi-finished fiber of ultrahigh molecular weight polyethylene; the semi-finished fiber enters a washing device after being subjected to hot drawing; and (3) carrying out heat setting on the fiber after washing to obtain the ultrahigh molecular weight polyethylene fiber. Compared with the prior art, in the scheme provided by the invention, the fiber is sequentially subjected to specific washing and heat setting processes before being wound so as to release internal stress, so that the mechanical property of the fiber is improved, and the variation rate of the fiber is improved.

Description

Ultra-high molecular weight polyethylene fiber and preparation method and application thereof

Technical Field

The invention belongs to the technical field of high polymer materials, and particularly relates to an ultrahigh molecular weight polyethylene fiber, and a preparation method and application thereof.

Background

Due to their high specific strength and high specific modulus, ultra-high molecular weight polyethylene fibers are widely used in ballistic articles, military equipment, armor, and the like. However, in the production process of the ultra-high molecular weight polyethylene fiber, internal stress is easily formed due to continuous orientation and crystallization of macromolecular chains, and if the internal stress is not eliminated, the surface of a product is not flat and the performance is not uniform in the post-processing process.

The nature of the internal stresses is the unbalanced conformation formed by the macromolecular chains during processing, which upon shaping cannot immediately return to the equilibrium conformation compatible with the environmental conditions. The unbalanced conformation is essentially a reversible high elastic deformation, while the frozen high elastic deformation is stored in the finished product in a potential energy form, and under proper conditions, the forced unstable conformation is converted into a free stable conformation, and the potential energy is converted into kinetic energy to be released. When the forces between the macromolecular chains and the entanglements cannot withstand this kinetic energy, the internal stress balance is disrupted and the article will undergo stress deformation. Therefore, a method is needed to reduce the internal stress of the fiber to the maximum extent, avoid stress concentration and improve the performance stability of the product.

Patent CN101629330A discloses that a negative draft less than 1 time is applied at 120-150 ℃ between two levels of positive drafts of gel precursor, which can effectively release the internal stress of the fiber, improve the mechanical properties of the fiber, and reduce the variation coefficient of the fiber. Patent CN106544747A discloses a method for producing ultra-high molecular weight polyethylene colored fiber, which adds a relaxation step after the hot drawing step, wherein the relaxation temperature is within ± 5 ℃ of the drawing temperature, and the relaxation draw ratio is not more than 1.00. Patent CN102433597A also discloses that the internal stress can be effectively released by applying negative draft with draft magnification of 0.7-0.9 at 90-120 ℃ to the fiber after positive draft.

The above techniques release internal stress of the fiber by heating and negative drawing, but the stress release time is limited because the length of the hot box is limited. Patent CN101684573A discloses that before stretching, the original filament is subjected to standing treatment at 1-25 ℃ to shrink the original filament, so that the internal stress of the original filament can be effectively removed, and the original filament has better tensile property. Although the method has enough time, the internal stress generated by the subsequent hot drawing cannot be released. The UD cloth and the composite material prepared by the fiber have uneven surfaces after hot pressing, are easy to bubble and have large fluctuation of V50 value.

Disclosure of Invention

Based on the problem of limited stress release of the high molecular fibers prepared in the prior art, the invention provides the ultra-high molecular weight polyethylene fiber and the preparation method and the application thereof.

According to the scheme provided by the invention, the fiber is sequentially subjected to specific washing and heat setting processes before being rolled so as to release internal stress, so that the mechanical property of the fiber is improved, the variation rate of the fiber is improved, and a product with stable performance is further prepared.

The purpose of the invention can be realized by the following technical scheme:

the invention firstly provides a preparation method of ultra-high molecular weight polyethylene fiber, which comprises the following steps:

1) Preparing ultra-high molecular weight polyethylene dry semi-finished fiber;

2) The semi-finished fiber enters a water washing device after being subjected to hot drawing;

3) And (3) carrying out heat setting on the washed fiber to obtain the ultra-high molecular weight polyethylene fiber.

In one embodiment of the present invention, in step 1), the ultra-high molecular weight polyethylene dry-state semi-finished fiber can be prepared by a conventional preparation method of ultra-high molecular weight fiber, for example, ultra-high molecular weight polyethylene resin powder, a solvent and a proper amount of auxiliary agent are fully mixed, and the mixture is swelled, dissolved, spun, stretched and the like to obtain the ultra-high molecular weight polyethylene dry-state semi-finished fiber.

In one embodiment of the present invention, in step 1), the ultra-high molecular weight polyethylene resin powder has a molecular weight of 400 to 600 ten thousand, a ratio Mw/Mn of weight average molecular weight Mw to number average molecular weight Mn of 3 to 7, preferably 3 to 5, and a proportion of particles of the ultra-high molecular weight polyethylene resin powder having a particle size of 120 to 220 μm of 50% or more, preferably 70% or more.

In one embodiment of the invention, in step 1), the solvent is selected from one or more of halogenated hydrocarbons, mineral oil, decalin, tetrahydronaphthalene, naphthalene, xylene, toluene, dodecane, undecane, decane, nonane, octene, chlorobenzene, petroleum ether or low molecular weight polyethylene wax in combination.

In one embodiment of the invention, in step 1), the auxiliary agent is selected from one or more of an antioxidant, a flow promoter, a heat stabilizer, a colorant or a combination of functional powders.

In an embodiment of the present invention, in step 1), when the ultra-high molecular weight polyethylene dry-state semi-finished fiber is prepared, the addition amounts of the ultra-high molecular weight polyethylene resin powder, the solvent and the auxiliary agent are adjusted according to the preparation method thereof, and no matter which method is selected, the quantitative relationship between the total solute and the solvent is related to the selection of the ultra-high molecular weight polyethylene resin powder, and can be determined by those skilled in the art according to the selection of the ultra-high molecular weight polyethylene resin powder.

In one embodiment of the present invention, in step 1), when preparing the ultra-high molecular weight polyethylene dry semi-finished fiber, the processes of swelling, dissolving, spinning, stretching, etc. are all conventional technical means of those skilled in the art.

In one embodiment of the present invention, in step 2), the hot drawing is selected to be one, two or more stages.

In one embodiment of the invention, in the step 2), the water washing device is composed of one or more connected tank bodies, the form of the tank bodies can be a horizontal tank, a vertical tank or other forms of shells, and the liquid flowing mode between the tank bodies is that the liquid overflows from back to front and is opposite to the running direction of the fibers.

In one embodiment of the invention, in step 2), the water washing device is provided with a plurality of active stretching rollers and passive stretching rollers, and the stretching tension control of the fiber is realized by adjusting the speed of the active stretching rollers, wherein the stretching tension control interval is 0.2-1.2CN/dtex, preferably 0.3-1.0CN/dtex. After the fiber is thermally drawn, cooling shrinkage occurs due to a thermal hysteresis effect, and the fiber is deformed due to stress release. Too much tensile tension will limit the shrinkage of the fibers and result in insufficient stress relief. The stretching tension is too small, and the running direction of the fiber is unstable under the vibration action of ultrasonic waves.

In one embodiment of the invention, in step 2), a water-absorbing felt is arranged at the outlet of the water washing device to reduce the liquid carrying amount of the fiber before heat setting as much as possible.

In one embodiment of the present invention, in step 2), the water washing device comprises a plurality of coils, and a heating or cooling medium can be introduced to control the water washing temperature. The temperature is related to product specifications, with a particular temperature being selected for a particular specification.

In one embodiment of the present invention, in step 2), the water washing device comprises an ultrasonic wave generating device, wherein the ultrasonic wave power is adjustable.

In one embodiment of the invention, in step 2), the soaking length of the water washing device is more than or equal to 10 meters, and more preferably more than or equal to 20 meters.

In one embodiment of the invention, in step 3), the heat-setting tensile force is less than or equal to 0.8CN/dtex, and the setting temperature is 120-135 ℃.

Further preferably, the heat-setting tensile force is less than or equal to 0.5CN/dtex. If the tension is higher than the above range, the resulting fiber will have large residual stress inside the fiber, large shrinkage deformation after winding, and dimensional change and mechanical property change after production of the bulletproof article, which is not preferable.

Further preferably, the setting temperature is 120-130 ℃. The heat-setting treatment can reduce internal stress, but the temperature is too high, which may cause rearrangement of molecular chains, and therefore, the temperature is selected to be far from the melting point. The effect of this heat treatment: firstly, remove the surplus moisture on the fibre surface, secondly improve the temperature, further promote the release of internal stress.

In one embodiment of the present invention, in step 3), the heat-setting time is 8 to 60s, more preferably 10 to 55s.

The invention also provides the ultrahigh molecular weight polyethylene fiber prepared based on the preparation method.

The invention also provides the application of the ultra-high molecular weight polyethylene fiber in preparing a bulletproof product.

In one embodiment of the invention, the ultra-high molecular weight polyethylene fiber is sequentially warped, spread, gummed, dried and rolled to obtain ultra-high molecular weight polyethylene single-layer UD cloth, and then the ultra-high molecular weight polyethylene single-layer UD cloth is compounded at 0/90 degrees to obtain fiber composite cloth, and the fiber composite cloth is made into soft bulletproof clothes or hard bulletproof armors.

According to the invention, before the fiber is rolled, the slow release of the internal stress of the fiber is promoted by a washing relaxation mode, and the fiber after washing is subjected to heat setting processing, so that the obtained fiber has smaller internal stress, better performance and better processing stability, and can be used for bulletproof products after being prepared into UD cloth and composite materials, the surface flatness is good, and the fluctuation of a V50 value is smaller.

The method for eliminating the internal stress can not only carry out heat treatment on the fiber, but also prolong the aging to eliminate the internal stress. The invention selects the water washing mode, not only fully considers the natural aging of the internal stress release, but also considers the surface cleaning of the fiber and fully purifies the surface of the fiber. Therefore, the fiber has better interlayer adhesion during subsequent processing, and the bulletproof product is not easy to delaminate and crack under the impact of bullets, thereby having better performance. The washing device is assisted with ultrasonic vibration, and the mode can optimize stress or change the direction of the stress, so that the residual stress of the fiber is smaller.

Compared with the prior art, the invention has the following technical advantages:

1) According to the technical scheme, a proper process is selected, the internal stress of the fiber is effectively removed, the performance of the fiber is improved, and the variation rate of the fiber is reduced.

2) UD and compound cloth that fibre processing among the technical scheme of this application made, the surfacing, the tympanic bulla is few, and the interlaminar adhesive force is strong moreover, and the product bulletproof performance is high, and the V50 value change is also little.

3) The composite cloth processing obtained product in the technical scheme of the application has light weight and thin thickness on the premise of ensuring the same protection grade.

4) After the technical scheme of this application is adopted, fibre residual stress is few, stable in structure, and hot drafting efficiency promotes, and whole simple operation has reduced manufacturing cost.

Detailed Description

The present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the scope of the invention. The characteristic values of the ultrahigh-molecular-weight polyethylene fibers obtained in the present invention were measured and evaluated as follows.

(1) Weight average molecular weight Mw, number average molecular weight Mn and Mw/Mn of the raw resin

The weight average molecular weight Mw, the number average molecular weight Mn and Mw/Mn are determined by Gel Permeation Chromatography (GPC). The measurement solvent used was o-dichlorobenzene, and the column temperature was set to 145 ℃. The sample concentration was set to 1.0mg/ml, and 200. Mu.l was injected for measurement. The calibration curve of the molecular weight was prepared by a universal calibration method using a polystyrene sample having a known molecular weight.

(2) Fiber denier, breaking Strength, elongation at Break, and modulus testing

The fineness of the fiber is measured according to GB/T14343-2008 chemical fiber filament linear density test method, and the breaking strength, the breaking elongation and the modulus of the fiber are measured according to GB/T19975-2005 high-strength fiber filament tensile property test method.

(3) Measurement of shrinkage

The test fiber sample was cut to 70cm and marked at a distance of 10cm from each end, i.e., the sample length was shown to be 50cm. Then, the fiber sample was suspended from the jig without applying a load thereto, and heated at 100 ℃ for 30 minutes in this state using a hot air circulation type heating furnace. Thereafter, the fiber sample was taken out from the heating furnace, sufficiently cooled to room temperature, and then the length of the position marked on the fiber sample was measured. The shrinkage is determined by the following equation. In addition, the average value of the measurement values of a plurality of times is used as the numerical value.

Shrinkage (%) =100 × (fiber sample length before heating-fiber sample length after heating)/(fiber sample length before heating)

(4) Interlaminar peeling test of fiber composite cloth

According to GB/T2791-1995 adhesive T peel strength test method, the peel strength of the composite material interface is tested, the peel strength is large, the interlayer adhesion is strong, otherwise, the interlayer adhesion is weak.

(5) Ballistic performance testing of fiber composite cloth

After the ultra-high molecular weight polyethylene fiber is made into composite cloth, the composite cloth is cut and stacked in multiple layers to obtain the soft bulletproof vest, and secondary bulletproof performance is measured according to the GA141-2010 police bulletproof vest standard, 7.62mm handgun bullets (lead core) in 1951 and the bullet speed of 445 +/-10 m/s. Or pressing the armor by a press to obtain the hard bulletproof armor, and measuring the four-level bulletproof performance according to the GA141-2010 police bullet-proof armor standard, 7.62mm type B pistol ammunition (steel core) in 1951 and the bullet speed of 515 +/-10 m/s.

The present invention will be described in detail with reference to specific examples. In the technical scheme, characteristics such as preparation means, materials, structures or composition ratios and the like which are not explicitly described are all regarded as common technical characteristics disclosed in the prior art.

Example 1:

the ultra-high molecular weight polyethylene resin powder with the molecular weight of 600 ten thousand, the molecular weight distribution range Mw/Mn of 5.5 and the particle size distribution range of 120-220 mu m of 67 percent is uniformly mixed with 0.5 percent of antioxidant IRGAFOS168, and then the mixture is injected into constant temperature mineral oil with the temperature of 45 ℃ according to the proportion of 1. Wherein, the swelling, dissolving, spinning and stretching related to the obtained ultra-high molecular weight polyethylene dry semi-finished fiber all adopt the conventional processes in the field.

After three-stage hot drafting, the semi-finished fiber enters two-stage connected vertical rinsing baths in sequence, and the soaking length of each bath body is 10 meters, which is 20 meters in total. The active draw roll was opened while the ultrasonic vibration generator was turned on and the fiber draw tension was adjusted to 0.5CN/dtex. After the fiber is washed, the fiber enters a heat setting device. The setting temperature was 130 ℃ and the time was 25 seconds, while the speed of the draw rolls was adjusted to a draw tension of 0.5CN/dtex.

After the fiber is heat-set, the fiber is rolled to obtain an ultra-high molecular weight polyethylene fiber finished product, then the ultra-high molecular weight polyethylene single-layer UD cloth is obtained through warping, spreading, gum dipping, drying and rolling, then the fiber composite cloth is obtained through 0 degree/90 degree compounding, and a plurality of layers are superposed after cutting to obtain a soft bulletproof vest, or the hard bulletproof armor is obtained through pressing by a press.

Example 2:

the difference from example 1 is that: the ultra-high molecular weight polyethylene resin powder has a molecular weight distribution range Mw/Mn of 3.0 and a particle size distribution range of 120-220 μm of 84%.

Example 3:

the difference from example 1 is that: the molecular weight of the ultra-high molecular weight polyethylene resin powder is 400 ten thousand, the molecular weight distribution range Mw/Mn is 7.0, and the particle size distribution range is 120-220 mu m, and the proportion is 50%.

Example 4:

the difference from example 1 is that: after the semi-finished fiber is subjected to three-stage hot drafting, the tensile tension of the semi-finished fiber entering a rinsing bath is adjusted to 1.0CN/dtex.

Example 5:

the difference from example 1 is that: and (3) after three-stage hot drawing, the semi-finished fiber enters a first-stage rinsing bath only, and the soaking length is 10 m.

Example 6:

the difference from example 1 is that: and (3) after three-stage hot drafting, sequentially feeding the semi-finished fibers into three-stage connected vertical rinsing tanks, wherein the soaking length of each tank body is 10 meters, and the total length is 30 meters. And opening the driving stretching roller, closing the ultrasonic vibration generator and adjusting the fiber stretching tension to be 0.3CN/dtex.

Example 7:

the difference from example 1 is that: the heat setting temperature was 135 ℃ and the time was selected to be 10 seconds, while the speed of the stretching roll was adjusted to a stretching tension of 1.0CN/dtex.

Example 8:

the difference from example 1 is that: the heat setting temperature was 120 ℃ and the time was 55 seconds, while the speed of the stretching roll was adjusted to a stretching tension of 0.3CN/dtex.

Comparative example 1:

the difference from example 1 is that: after the semi-finished fiber is subjected to three-stage hot drawing, the semi-finished fiber does not pass through a washing device, but passes through a hot setting device. The heat setting temperature was 130 ℃ and the time was 25 seconds, while the speed of the drawing roll was adjusted to a drawing tension of 0.5CN/dtex.

Comparative example 2:

the difference from example 1 is that: by adopting the conventional hot drawing process in the industry, a washing device is not needed, the hot setting process of the scheme is not used, the temperature for hot setting is 145 ℃, the time is selected to be 8s, meanwhile, the drawing multiple is adjusted to be 1 time, and the drawing tension is about 1.2CN/dtex.

The raw materials and process parameters of the above examples and comparative examples are shown in table 1, and the performance test results of the ultra-high molecular weight polyethylene fibers, the fiber composite cloth and the products are shown in table 2.

TABLE 1 raw materials and Process parameters for the examples and comparative examples

TABLE 2 results of performance tests on ultra-high molecular weight polyethylene fibers, fiber composite fabrics, and articles prepared therefrom

According to the test results, the fiber product prepared by the method has good performance, low mutation rate, good bonding between fiber composite cloth layers and stable performance of the obtained product.

The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make modifications and alterations without departing from the scope of the present invention.

Claims

1. A preparation method of ultra-high molecular weight polyethylene fiber is characterized by comprising the following steps:

1) Preparing dry semi-finished fiber of ultra-high molecular weight polyethylene;

2) The semi-finished fiber enters a washing device after being subjected to hot drawing;

2. The method for preparing ultra-high molecular weight polyethylene fiber according to claim 1, wherein in step 1), the ultra-high molecular weight polyethylene dry semi-finished fiber is prepared by mixing ultra-high molecular weight polyethylene resin powder, a solvent and an auxiliary agent, and performing swelling, dissolving, spinning and stretching;

the molecular weight of the ultra-high molecular weight polyethylene resin powder is 400-600 ten thousand, the ratio Mw/Mn of the weight average molecular weight Mw to the number average molecular weight Mn is 3-7, preferably 3-5, and the proportion of the ultra-high molecular weight polyethylene resin powder particles with the particle size of 120-220 mu m is more than or equal to 50 percent, preferably more than or equal to 70 percent.

3. The method of claim 1, wherein the heat-drawing step 2) is performed in one, two or more stages.

4. The method for preparing ultra-high molecular weight polyethylene fiber according to claim 1, wherein in the step 2), the water washing device is composed of one or more connected tank bodies, and the liquid flowing mode among the tank bodies is that the liquid overflows from back to front and is opposite to the running direction of the fiber.

5. The method for preparing ultra-high molecular weight polyethylene fiber according to claim 1, wherein in step 2), the water washing device is provided with a plurality of active stretching rollers and passive stretching rollers, the stretching tension control of the fiber is realized by adjusting the speed of the active stretching rollers, and the stretching tension control range is 0.2-1.2CN/dtex, preferably 0.3-1.0CN/dtex.

6. The method for preparing ultra-high molecular weight polyethylene fiber according to claim 1, wherein in step 2), the water washing device comprises an ultrasonic generating device, wherein the ultrasonic power is adjustable.

7. The method for preparing ultra-high molecular weight polyethylene fiber according to claim 1, wherein in step 2), the soaking length of the water washing device is not less than 10 meters, and more preferably not less than 20 meters.

8. The method for preparing ultra-high molecular weight polyethylene fiber according to claim 1, wherein in step 3), the heat setting tensile force is less than or equal to 0.8CN/dtex, the setting temperature is 120-135 ℃, and the heat setting time is 8-60s;

preferably, the heat setting tensile force is less than or equal to 0.5CN/dtex, the setting temperature is 120-130 ℃, and the heat setting time is 10-55s.

9. The ultra-high molecular weight polyethylene fiber produced based on the production method according to any one of claims 1 to 8.

10. Use of the ultra high molecular weight polyethylene fiber according to claim 9 for the preparation of ballistic resistant articles.