CN107988632B

CN107988632B - UHMWPE fiber production and batching method capable of realizing continuous and uniform feeding

Info

Publication number: CN107988632B
Application number: CN201711195547.1A
Authority: CN
Inventors: 姚湘江; 陈宏�
Original assignee: Longyou Longxian New Material Co ltd
Current assignee: Longyou Longxian New Material Co ltd
Priority date: 2017-11-24
Filing date: 2017-11-24
Publication date: 2020-04-24
Anticipated expiration: 2037-11-24
Also published as: CN107988632A

Abstract

The invention provides a novel UHMWPE fiber production and batching method capable of realizing automatic continuous uniform feeding, which comprises the following steps: step 1) preparing 0.1-1% UHMWPE solution; step 2) placing the small materials into a strong shearing and bulk dispersing device for shearing and dispersing until the small materials are uniform and stable; step 3) feeding UHMWPE powder, the UHMWPE solution prepared in the step 1) and the small material obtained in the step 2) respectively through a weightless scale; the weightlessness scale is provided with an automatic feeding device. The loss control of a weightless scale is adopted, the feeding is automatic, continuous and uniform, and the batching error is less than 0.1%; the batching precision is improved to 0.097% from 1.2%, under the same production condition, the titer CV value of the UHMWPE fiber is reduced to 0.52% from 3.1%, the achievable super-power stretching proportion of the fiber is improved by 3-10%, and the strength, the modulus, the wear resistance, the thermal conductivity, the creep resistance and the like of the fiber are improved; the strength of the product is more than 42g/d, and the modulus is more than 1650 g/d.

Description

UHMWPE fiber production and batching method capable of realizing continuous and uniform feeding

Technical Field

The invention belongs to the field of UHMWPE fiber production, and particularly relates to a UHMWPE fiber production batching method for realizing continuous and uniform feeding.

Background

UHMWPE (ultra-high molecular weight polyethylene) is thermoplastic engineering plastic with linear structure molecules and excellent comprehensive performance, and the molecular weight is up to more than 150 ten thousand. The UHMWPE fiber is a flexible chain high molecular polymer with high strength and high modulus, and the molecular microstructure is extremely regular. Because of the inertia of the chemical structure and the highly oriented and highly crystallized structure, the fiber has excellent performance in both chemical performance and physical performance, has mechanical properties which cannot be compared with other high-performance fibers, and becomes a third-generation high-performance fiber which appears after carbon fiber and aramid fiber. Low density, high antiwear performance, self-lubricating performance, impact resistance, corrosion resistance, etc.

The main steps of the ultra-high molecular weight polyethylene gel spinning wet spinning method at the present stage of China are briefly described as follows: adding ultrahigh molecular weight polyethylene into a proper solvent, stirring and dissolving to prepare a suspension, extruding the suspension by a screw extruder, extruding and molding through a spinneret orifice, cooling, extracting, drying and stretching to obtain the finished fiber.

The preparation of the uniform solution of the ultra-high molecular weight polyethylene is one of the key processes of the polyethylene gel spinning, and the preparation directly influences the mechanical property, the production cost, the efficiency, the equipment investment and other important factors of the obtained fiber. It is known that polyethylene lacks good solvents, its solubility in solvents decreases significantly with increasing molecular weight of the polyethylene, the concentration of soluble components decreases and can be achieved by heating at high temperatures for a long time, and thermo-oxidative degradation of polyethylene during dissolution is unavoidable, leading to a broadening of the molecular weight distribution, thereby compromising the mechanical properties of the resulting fibers. The existing ingredients are all reaction kettle type intermittent ingredients, UHMWPE powder and white oil are added into a kettle at one time, UHMWPE powder/white oil suspension is formed under the condition of a certain temperature and stirring rate, and the suspension is pumped into a feeding kettle through a pump to complete the ingredient feeding process. The batching mode has large deviation between batches, the density difference between white oil and UHMWPE powder exists, the density of the white oil is about 0.78, the density of the UHMWPE is about 0.95, the concentration gradient of the UHMWPE powder in the vertical direction cannot be completely eliminated under the condition that kettle-type batching is fully stirred, the stirring dead angle exists in a reaction kettle, stirring cannot be realized in a feeding pipeline, and the batching difference is more obvious. The difference is reflected in production, the melt viscosity and the nose pressure have periodic fluctuation, the deviation can reach 10%, and further the titer of the product and the molecular conformation of UHMWPE are influenced, and finally the performance of the product is caused.

Disclosure of Invention

In order to solve the above problems, the present invention provides a novel UHMWPE fiber production and compounding method capable of achieving automatic continuous uniform feeding, comprising the steps of: step 1) preparing 0.1-1% UHMWPE solution; step 2) placing the small materials into a strong shearing and bulk dispersing device for shearing and dispersing until the small materials are uniform and stable; step 3) feeding UHMWPE powder, the UHMWPE solution prepared in the step 1) and the small material obtained in the step 2) respectively through a weightless scale; the weightlessness scale is provided with an automatic feeding device.

The preparation method of the 0.1-1% UHMWPE solution in the step 1) comprises the following steps: putting a polyolefin antioxidant, UHMWPE powder and a solvent into a reaction kettle; wherein the mass of the polyolefin antioxidant accounts for 5-10% of that of the UHMWPE powder; gradually heating and stirring to dissolve. The solvent is one or more of white oil, paraffin oil, decalin and mineral oil. The polyolefin antioxidant is selected from common antioxidants produced by UHMWPE in the prior art, and comprises a main antioxidant, such as a hindered phenol antioxidant, and a secondary antioxidant, such as a phosphite ester/phosphate ester compound, a thioether compound and the like, and the composite use effect is better, but the main antioxidant and the secondary antioxidant can be independently used.

Preferably, the small materials in the step 2) are selected from one or more of antioxidants, dispersing agents or nano-to micron-sized fine particles.

Preferably, the strong shear dispersing device in the step 2) is selected from a shear kettle, a shear emulsifying machine or a shear emulsifying pump.

Preferably, the weight loss scales in the step 3) are three scales, namely an UHMWPE powder scale, an UHMWPE solution scale and a small material scale, and each scale is provided with a plurality of scales, wherein the UHMWPE powder scale, the UHMWPE solution and the small material scale are respectively used for realizing the UHMWPE powder, the UHMWPE solution prepared in the step 1), and the small material obtained by shearing and dispersing in the step 2) is fed in a metering manner.

Preferably, the automatic feeding devices of the UHMWPE powder scale and the UHMWPE solution scale are hoppers.

Preferably, the automatic material supplementing device of the small material scale is an intermediate kettle with a stirring and constant temperature device.

Preferably, the automatic feeding device is provided with a bridge breaking device selected from a bridge breaking oscillator, a bridge breaking stirrer or a gas flow bridge breaking.

Preferably, the method comprises the steps of:

1) preparing an UHMWPE solution with the concentration of 0.1-1%, and adding a polyolefin antioxidant, UHMWPE and white oil which are accurately metered into a reaction kettle, wherein the mass of the polyolefin antioxidant accounts for 0.5-5% of that of UHMWPE powder;

gradually raising the temperature to 140-180 ℃ under stirring, wherein the stirring time is 0.5-2 h; adding a certain amount of cold white oil to lower the temperature of UHMWPE/white oil to below 120 deg.C for use

2) Putting the small materials into a strong shearing and bulk dispersing device with the stirring speed of 2000-10000 r/min, and shearing and dispersing the small materials to be uniform and stable at the temperature of 25-120 ℃;

3) the weightlessness scale is used for realizing continuous and uniform feeding: setting three weight loss scales, wherein each weight loss scale comprises a plurality of UHMWPE powder scales, an UHMWPE solution scale and a small material scale which are respectively used for realizing the powder, and the UHMWPE solution in the step 1) and the small material in the step 2) are metered and fed;

4) automatic material supplementing: the hopper is used as a powder scale or an UHMWPE solution scale for automatic material supplementing, and the hopper is provided with a bridge breaking device to prevent the UHMWPE powder from bridging; feeding UHMWPE solution, and carrying out external heat preservation treatment on the liquid scale; the middle kettle with stirring and constant temperature device is supplemented with small material scale with stirring and external constant temperature device.

Preferably, in the step 3): based on the mass sum of the UHMWPE powder, the UHMWPE/white oil uniform dilute solution and the small material, the mass fraction of the UHMWPE powder is 10-15%; the mass fraction of the small materials is 1-15%; wherein, UHMWPE powder is fed into the double screw at the speed of 42 kg/h-842 kg/h, and the feeding speed of UHMWPE/white oil even dilute solution and small material is set according to the mass proportion.

By adopting the technical scheme, compared with the prior art, the invention has the following beneficial effects:

the UHMWPE/dilute solution feeding is adopted, so that the conveying capacity of the double screw can be improved; the output precision of the liquid weightless scale can be improved, and the actual measurement result shows that the white oil is directly fed, the precision of the scale is higher than 0.2 percent, the UHMWPE/white oil dilute solution is used for feeding, and the output precision of the weightless scale can be reduced to be below 0.1 percent; 0.1 to 1 percent of UHMWPE powder is dissolved before double-screw feeding, and the total yield can be improved by 2 to 10 percent.

Compared with the traditional kettle type intermittent batching mode, the loss control of the weightless scale is adopted, the feeding is automatic, continuous and uniform, and the batching error is less than 0.1%; the batching precision is improved to 0.097% from 1.2%, under the same production condition, the titer CV value of the UHMWPE fiber is reduced to 0.52% from 3.1%, the achievable super-power stretching proportion of the fiber is improved by 3-10%, and the strength, the modulus, the wear resistance, the thermal conductivity, the creep resistance and the like of the fiber are improved; the strength of the product is more than 42g/d, and the modulus is more than 1650 g/d.

Detailed Description

Example 1

1) Preparing a uniform solution of UHMWPE/white oil with the concentration of 0.1-1%; adding accurately metered polyolefin antioxidant, UHMWPE and white oil into UHMWPE powder, the polyolefin antioxidant and the white oil in a reaction kettle, wherein the mass of the polyolefin antioxidant accounts for 5-10% of that of the UHMWPE powder;

gradually raising the temperature to 140 ℃ while stirring, stirring for 10-30 min, continuously raising the temperature to 160 ℃, stirring for 10-30 min, and continuously raising the temperature to 180 ℃. Obvious pole climbing effect can occur in the dissolution process of UHMWPE, and the stirring rotating speed can be properly reduced when the pole climbing effect occurs according to the production condition. Keeping the temperature and stirring for 30min after the temperature reaches 180 ℃. Adding a certain amount of cold white oil to reduce the temperature of UHMWPE/white oil to below 120 ℃ for standby. The UHMWPE/white oil dilute solution to be used.

The purpose of feeding with a dilute UHMWPE/white oil solution, rather than a pure white oil feed, is: (1) the double screws have weak capacity of conveying low-viscosity liquid, the viscosity of the liquid inlet is improved, and the conveying capacity of the double screws can be improved; (2) the UHMWPE/white oil homogeneous dilute solution is prepared, the output precision of the liquid weightlessness scale can be improved, the actual measurement result shows that the white oil is directly fed, the precision of the scale is higher than 0.2 percent, the UHMWPE/white oil dilute solution is fed, and the output precision of the weightlessness scale can be reduced to be lower than 0.1 percent; (3) 0.1 to 1 percent of UHMWPE powder is dissolved before double-screw feeding, and the total yield can be improved by 2 to 10 percent.

2) A strong shearing small material batching device; stirring at 2000-10000 rpm, cutting into bulk, adding antioxidant, dispersant and nanometer to micron level fine grains, and shearing at 25-120 deg.c to disperse homogeneously and stably; the strong shearing dispersion device is mature industrial equipment and is widely applied to the fields of paint, coating, cosmetics and the like, such as a shearing kettle, a shearing emulsifying machine, a shearing emulsifying pump and the like.

The antioxidant comprises a primary antioxidant, such as hindered phenol antioxidant, and a secondary antioxidant, such as phosphite ester/phosphate ester compound and thioether compound, and the compound effect is better, but the primary antioxidant and the secondary antioxidant can be used independently.

The dispersing agent can be one or more of polyoxyethylene, fatty alcohol polyoxyethylene ether methylsilane, oleic acid polyoxyethylene ester, sodium carboxymethylcellulose, sodium alkyl diphenyl ether sulfonate, alkylphenol polyoxyethylene ether phosphate, octadecyl amine, methylcellulose, tween-80, tween-60, sodium pyrophosphate, sodium hexametaphosphate and the like.

3) Realizing UHMWPE powder, UHMWPE/white oil uniform dilute solution or continuous uniform feeding by a weightless scale; setting three weightless scales, namely a plurality of UHMWPE powder scales, a liquid scale and a small material scale; the UHMWPE powder scale, the liquid scale and the small material scale are respectively used for realizing the metering feeding of UHMWPE powder, UHMWPE solution in the step 1) and small material obtained in the step 2); wherein, the UHMWPE powder scale can be used for feeding in a single screw or double screw mode, and the UHMWPE solution scale and the small material scale can be used for feeding in a gear pump, a plunger pump or a diaphragm pump and the like; adding the UHMWPE/white oil dilute solution to be used into a weightlessness balance stock bin.

In a preferred embodiment of the invention, the mass fraction of the UHMWPE powder is 10-15% calculated by the sum of the mass of the UHMWPE powder, the UHMWPE/white oil homogeneous dilute solution and the small material; the mass fraction of the small materials is 1-15%; wherein UHMWPE powder is fed into a double screw or a single screw at a certain speed, preferably the speed of 42 kg/h-842 kg/h is set to be fed into the double screw, and the feeding speed of UHMWPE/white oil uniform dilute solution and small material is set according to the mass ratio.

Feeding UHMWPE powder and an UHMWPE/white oil homogeneous dilute solution by adopting a hopper respectively, wherein in order to ensure smooth feeding, the powder hopper is provided with a bridge breaking device to prevent the UHMWPE powder from bridging; when the feeding material is UHMWPE solution, the oil weigher needs to be subjected to external heat preservation treatment, so that the working precision of the weightless weigher is prevented from being reduced due to temperature reduction and viscosity increase of the dilute solution. The bridge breaking device can be a bridge breaking oscillator, a bridge breaking stirrer, an airflow bridge breaking device and the like.

The ingredients enter an intermediate kettle with a stirring and constant temperature device, and the intermediate kettle supplements the ingredients for the small material scale, and the small material scale also needs to be provided with a stirring and external constant temperature device to avoid the separation or agglomeration of small material components.

Example 2

Calculating the difference value between the actual feeding speed and the set value in the embodiment 1 by using the working curve of the weightlessness scale, and calculating the batching error; the results demonstrate dosing error < 0.1%.

By detecting the change of the on-line viscosity of the screw discharging, the change of the melt viscosity within a period of time is tested because the feeding deviation is in direct proportion to the change of the screw discharging viscosity, and the result proves that the batching precision is improved to 0.097% from 1.2%.

By adopting the batching method obtained in the embodiment 1, (1) the batching precision is higher, the unevenness is less than 0.1 percent, and the influence of the unevenness in batching on the product quality is reduced; (2) the product performance is improved by improving the consistency of the product; (3) various inorganic particles are added, so that different functions of the UHMWPE fiber are realized, wherein the functions are as shown in the table 1; (4) switching product specifications produces less waste than kettle-type compounding.

The strength of the obtained final ultra-high molecular weight polyethylene fiber product is more than 42g/d, and the modulus is more than 1650 g/d.

After a weightless scale type alternative kettle type batching mode is adopted, the batching precision is improved from 1.2% to 0.097%, under the same production condition, the titer CV value of the UHMWPE fiber is reduced from 3.1% to 0.52%, the achievable over-doubling tensile ratio of the fiber is improved by 3-10%, and the strength, the modulus, the wear resistance, the thermal conductivity, the creep resistance and the like of the fiber are improved.

From the foregoing, it will be appreciated that, although specific embodiments have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention.

Claims

1. A UHMWPE fiber production batching method for realizing continuous and uniform feeding is characterized in that: the method comprises the following steps: step 1) preparing 0.1-1% UHMWPE solution; step 2) placing the small materials into a strong shearing and bulk dispersing device for shearing and dispersing until the small materials are uniform and stable; step 3) feeding UHMWPE powder, the UHMWPE solution prepared in the step 1) and the small material obtained in the step 2) respectively through a weightlessness scale, wherein the weightlessness scale is provided with an automatic feeding device;

the small materials are selected from one or a mixture of an antioxidant and a dispersant.

2. The UHMWPE fiber production batching process achieving continuous uniform feeding according to claim 1, characterized in that: the preparation method of the 0.1-1% UHMWPE solution in the step 1) comprises the following steps: putting a polyolefin antioxidant, UHMWPE powder and a solvent into a reaction kettle; wherein the mass of the polyolefin antioxidant accounts for 5-10% of that of the UHMWPE powder; gradually heating and stirring to dissolve.

3. The UHMWPE fiber production batching process achieving continuous uniform feeding according to claim 1, characterized in that: the strong shear dispersing device in the step 2) is selected from a shear kettle, a shear emulsifying machine or a shear emulsifying pump.

4. The UHMWPE fiber production batching process achieving continuous uniform feeding according to claim 1, characterized in that: the weight loss scale in the step 3) is divided into an UHMWPE powder scale, an UHMWPE solution scale and a small material scale, wherein each of the UHMWPE powder scale, the UHMWPE solution scale and the small material scale is provided with a plurality of scales, and the UHMWPE powder scale, the UHMWPE solution and the small material scale are respectively used for realizing UHMWPE powder, UHMWPE solution prepared in the step 1) and small material metering feeding of small materials obtained by shearing and dispersing in the step 2).

5. The UHMWPE fiber production compounding process achieving continuous homogeneous feeding according to claim 4 characterized in that: the automatic feeding device of the UHMWPE powder scale and the UHMWPE solution scale is a hopper.

6. The UHMWPE fiber production compounding process achieving continuous homogeneous feeding according to claim 4 characterized in that: the automatic material supplementing device of the small material scale is an intermediate kettle with a stirring and constant temperature device.

7. The UHMWPE fiber production batching process achieving continuous uniform feeding according to claim 1, characterized in that: the automatic feeding device is provided with a bridge breaking device, and the bridge breaking device is selected from a bridge breaking oscillator, a bridge breaking stirrer or an airflow bridge breaking device.

8. The UHMWPE fiber production batching method achieving continuous and uniform feeding according to any one of claims 1 to 7, characterized in that: the method comprises the following steps:

9. The UHMWPE fiber production compounding process achieving continuous homogeneous feeding according to claim 8 characterized in that: in the step 3): based on the mass sum of the UHMWPE powder, the UHMWPE/white oil uniform dilute solution and the small material, the mass fraction of the UHMWPE powder is 10-15%; the mass fraction of the small materials is 1-15%; wherein, UHMWPE powder is fed into the double screw at the speed of 42 kg/h-842 kg/h, and the feeding speed of UHMWPE/white oil even dilute solution and small material is set according to the mass proportion.