KR100274792B1 - Continuous production process of high strength and high-modulus polyethylene materials - Google Patents

Abstract

PURPOSE: A producing process for a polyethylene material having high strength and flexibility is provided to improve producing property and reduce producing cost through processing polyethylene by using a simple device under a melting point. CONSTITUTION: A material passes through an input unit(1) and a compressing unit(2). Width and string number of the material are decided in a slitting unit(3). Then, the material passes through a first drawing unit(4) formed by compressing rollers. Herein, rotating speeds and temperatures of the rollers are adjusted for controlling drawing temperature to be under a melting point. The material is pre-heated in a pre-heating unit(5) having compressing rollers to be transferred to a second drawing unit(6) formed by heated plates. Herein, the plates are in a convex state for improving contact with the material. Then, the material is wound up in a winding unit(7).

Description

Manufacturing process of high strength, high elastic polyethylene material

The present invention relates to a process for manufacturing a high strength, high elastic polyethylene material by processing ultra high molecular weight polyethylene (UHMWPE) at a melting point, in particular a device employing a plurality of rollers of polyethylene resin at a melting point without using an organic solvent. By proceeding sequentially through so that the stretching is carried out continuously at the same time relates to a process for producing a material, such as high strength, high elastic polyethylene fiber, film, sheet.

Generally, ultra high molecular weight polyethylene refers to polyethylene having a molecular weight of 10 ⁶ or more, and its largest use is a high strength polyethylene fiber highly oriented ultra high molecular weight polyethylene, which has a very good absorption of impact energy, and thus is widely used in the field of strong impact. In addition, since the density is very low, the specific strength, inelasticity is excellent, and the weight can be reduced.

Currently, high-strength, high-elasticity polyethylene products manufactured by using a gel spinning method in which a small amount of ultra high molecular weight polyethylene is added to an organic solvent such as decarin or paraffin, and then the polymer solution is extruded and stretched and then the organic solvent is removed are commercialized. .

However, since the gel spinning method involves a difficult process of preparing, spinning, and stretching a high-temperature, low-concentration polyethylene solution, the cost of production is high, and inherently environmentally harmful factors related to the recovery of the organic solvent are inherent. Nevertheless, its application is quite limited.

Therefore, a solid phase process in which only ultra-high molecular weight polyethylene is compressed and stretched under a melting point without using an organic solvent has been proposed and developed as a method for producing an environment-friendly and low-cost ultra high molecular weight polyethylene product.

European Patent Publication No. EP253513A2 discloses a method of processing ultra-high molecular weight polyethylene without using an organic solvent and extruding powdered polyethylene under a melting point into a cylinder and drawing it. However, the two-step method in which the solid-state extrusion process and the stretching process are separated from each other makes it impossible to continuously manufacture the product in the form of fibers or tapes, and the solid-state extrusion rate is too low at 0.24 CM / min to obtain commercial productivity. Can't.

In addition, European Patent Publication No. EP374785A1 constitutes an apparatus including two belts driven and circulated by rollers connected to each other by a method of processing ultra high molecular weight polyethylene without using an organic solvent, and powdered polyethylene between the belts. The present invention discloses a method of compressing and molding ultra high molecular weight polyethylene under melting point by injecting and compressing the same. However, this method also has a problem that excessive installation cost is required because a complicated and huge endless belt is used for simple pressing of the resin.

Accordingly, an object of the present invention is to improve the processability and reduce the manufacturing cost by processing the powdery ultra high molecular weight polyethylene through a simple device at the melting point without using an organic solvent as an environmentally friendly manufacturing process to solve the above problems. The present invention provides a process for producing a high strength, high elastic polyethylene material.

In order to achieve the object as described above, the process of the present invention comprises the step of compressing the ultra-high molecular weight polyethylene powder into a roller formed with a stepped groove maintained at a pressure of 200 ~ 1000MPa and 80 ~ 135 ℃; Passing the compressed resin through a plurality of heated rollers to first draw at a draw ratio of 1.1 to 10 at 110 to 140 ° C., wherein the at least one heated plate is maintained at 115 to 150 ° C. Second drawing using a drawing ratio of 1.1 to 15; And winding the secondary stretched resin.

The manufacturing process of the high strength, high elastic polyethylene material according to the present invention as described above solves the conventional problems, that is, many problems in productivity and manufacturing cost according to the manufacturing technology for compressing and stretching the polyethylene resin under the melting point. In addition, it is possible to manufacture a high-strength, high-elastic polyethylene material in an environmentally friendly way by simplifying the compression and stretching facilities to effectively compress and stretch the resin and without using an organic solvent.

1 is a perspective view schematically showing the ruler of the compression section used in the manufacturing process of the high strength, high elastic polyethylene material according to the present invention,

2 is a process diagram schematically showing a manufacturing process of a high strength, high elastic polyethylene material according to the present invention,

3 is a process diagram schematically illustrating a state in which a bobbin holder is added according to an embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

1: Raw material input part 2: Compression part

3: splitting part 4: primary drawing part

5: preheating part 6: secondary drawing part

7: winding unit 8: bobbin holder

9: extrusion roller

Hereinafter, the configuration of the present invention will be described in more detail with reference to the accompanying drawings.

In the accompanying drawings, Figure 1 is a perspective view schematically showing the roller of the compression unit of the high-strength, high-elasticity polyethylene material manufacturing apparatus according to the present invention, Figure 2 is a process diagram schematically showing a manufacturing process of a high-strength, high-elasticity polyethylene material according to the present invention 3 is a process diagram schematically illustrating a state in which a bobbin holder is added according to an embodiment of the present invention.

In the drawings, reference numeral 1 denotes a raw material input part, 2 a compression part, 3 a splitting part, 4 a primary drawing part, 5 a preheating part, 6 a secondary drawing part, 7 a winding part, 8 a bobbin holder and 9 The compression roller is shown.

As shown in FIG. 1, the compression unit 2 is composed of two rollers 9 having stepped grooves to be engaged with each other. Each of the rollers 9 may be heated to a predetermined temperature electrically or by using heat oil, and the driving speed of the rollers 9 may be adjusted. A powdery polyethylene resin is passed between the two rollers 9 at a temperature below the melting point and is continuously compressed and stretched at the same time. Therefore, by adjusting the amount of resin to be injected, the pressure applied to the step groove portion of the roller, and the driving speed of the roller 9, the thickness and the degree of compression of the compact can be adjusted.

The roller apparatus for plastic processing generally used is configured to obtain an extruded material having a constant thickness at a processing temperature above the melting point of the resin injected while the two rollers 9 rotate at predetermined intervals, whereas the compression roller of the present invention is used. At the same time, the step is formed in each roller to be engaged with each other during rotation, and the resin passes through the resin at a melting point or less therebetween, thereby being stretched in the rotational direction simultaneously with compression.

As shown in FIG. 2, the compressed material that has passed through the injection unit 1 and the compression unit 2 for supplying the resin has a width and the number of strands adjusted in the splitting unit 3. The compressed product passing through the splitting portion is initially drawn through the primary stretching portion 4 composed of three or more compression rollers. Each roller of the primary stretching portion can adjust the degree of stretching below the melting point because the rotational speed and temperature can be adjusted. The primary stretching portion 4 includes a compression roller for preheating for the secondary stretching and to prevent slipping during the secondary stretching, and the stretched material passing through the primary stretching portion 4 is also equipped with a compression roller. After being preheated in the preheating unit 5, it is transferred to the secondary stretching unit 6, which is a heated plate. The secondary stretched portion 6 maintains a constant temperature of the stretched article through surface contact with the stretched article. In the secondary drawing, the plate preferably has a somewhat convex surface in order to improve contact with the polyethylene material. In addition, during secondary drawing, the plate uses one or more, preferably one to eight heated plates, and the surface temperature of three or more parts, preferably 3 to 8 parts, can be adjusted independently. Before and after the heated plate, the secondary draw ratio can be adjusted as the roller rotational speed ratio of the preheater 5 to which the compression roller is attached, and winding of the stretched article finished in the winding section 7 is performed.

In the apparatus, the preheating unit and the secondary stretching unit for the secondary stretching may be configured in plural as necessary, and the bobbin as shown in FIG. 3 when additional stretching of the secondary stretched material without addition of equipment is required. Further stretching may be achieved by placing the holder 8 before the preheating section 5 and repeating the stretching process.

Referring to the process of producing a high-strength, high-elasticity polyethylene material using the manufacturing apparatus of the present invention described above is as follows.

The ultrahigh molecular weight polyethylene resin used in the present invention is a liquid component containing titanium (Ti (OR) _n X _4-n ), wherein R is an alkyl group, an aryl group or an alalkyl group having 1 to 20 carbon atoms , X is halogen, n is an integer from 0 to 4), organoaluminum compound (R ₃ AL or R ₂ ALOR, where R is an alkyl group, aryl group or alalkyl group of 1 to 20 carbon atoms), halogenated organoaluminum compound (R ₃ ALX, RALX ₂ , RAL (OR) X, or R ₃ AL ₂ X ₃ , wherein R is an alkyl group having 1 to 20 carbon atoms, an aryl group or an alalkyl group, X is a halogen), an ether organic compound (R'OR ', Where R 'is an alkyl group having 2 to 7 carbon atoms and a metal catalyst obtained by reacting a metal-magnesium with an organoaluminum compound and a halogenated hydrocarbon. It is prepared by polymerizing ethylene gas at a temperature and atm of 0.7 to 3. The method has been filed by the present applicant under the same name as the present invention, "the manufacturing method of ultra high molecular weight polyethylene", the contents of which are all included in the present invention. When ethylene gas is synthesized at room temperature by the above method, it is possible to obtain a powdery polyethylene having an intrinsic viscosity of 10 to 40 dl / g under a 135 ° C decalin solution. The polyethylene powder obtained by the above method has a low apparent specific gravity and has a microstructure suitable for compression and stretching at low temperature.

According to the present invention, the polyethylene powder is continuously compressed and stretched while passing through the roller of the compression unit 2 heated to a pressure of 200 to 1000 MPa and 80 to 135 ° C. At this time, if it is less than 200 MPa, the compression is insufficient and stretching is difficult, and if it exceeds 1000 MPa, the compression is uneven and the defect of the compressed product increases. In addition, if the temperature is less than 80 ° C, the compressed product is brittle, and there is a high possibility of cutting at the time of stretching.

This compact is initially drawn in the primary drawing section 4 consisting of a plurality of heated rollers and secondly drawn in the plate of the heated secondary drawing section 6. The temperature of the roller of the primary stretching section and the plate of the secondary stretching section is maintained below the melting point of the resin at about 110 to 140 ° C. and 115 to 150 ° C., respectively. Highly elastic polyethylene materials are produced. In addition, the stretching ratio can be performed to a desired degree by repeatedly performing the primary stretching step and the secondary stretching step. In the first and second calculations, the draw ratio is preferably 1.1 to 10. If the draw ratio is less than 1.1, the drawing does not occur and the strength does not increase. If the draw ratio exceeds 10, the draw ratio is difficult to draw during the second drawing. The draw ratio is preferably from 1.1 to 15. If the draw ratio is less than 1.1, the draw is paralyzed. If the draw ratio is greater than 15, the fibers are frequently cut, which makes continuous drawing difficult. In addition, the total draw ratio is 10 to 150 is preferred, less than 10, the draw is insufficient, the fiber strength is low, and if it exceeds 150 it is difficult to continuous work because of the high possibility of cutting the fiber.

The shape of the material thus prepared may be fibrous, film, or sheet, and in the case of fibrous, its thickness is 0.2 mm or less and width is 2.5 mm or less.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the scope of the present invention is not limited to the following Examples.

[Production Example 1]

Preparation of Liquid Containing Magnesium

15 g of metal-magnesium, 60 ml of normal-heptane, 5 ml of 1-chlorobutane, and 6 mmol of triethylaluminum are mixed in a glass flask container under a nitrogen atmosphere. Raise the temperature above 98 ° C. (boiling point of heptane) and stir for 20 minutes. Then, a solution containing 54 g of 1-chlorobutane dissolved in normal-heptane (440 mL) was added dropwise for 1 hour. After the temperature was maintained for 2 hours, 0.159 mol of triethylaluminum was added thereto. After that, it is heated for 1 hour. After filtering out the precipitate, the remaining solution will contain approximately 7.4 g / l of magnesium, which is used for ethylene synthesis.

[Production Example 2]

200 ml of normal-heptane, 0.12 ml of triethylaluminum (1M heptane solution), 1.76 ml of magnesium-organic solution prepared in Preparation Example 1 above, 1.8 mg of tetrahytrofuran, 0.128 in a 300 ml reactor under nitrogen atmosphere. g of diethylaluminum chloride, 0.58 mg of titanium tetra chloride, and the like are added thereto, and the ethylene gas pressure is 1 atm. When the reaction is carried out for 1 hour while maintaining the temperature at 25 ° C. and the gas pressure at 1 atmosphere, ultrahigh molecular weight ethylene having a viscosity of 15.4 (decalin, at 135 ° C.) is synthesized. At this time, the catalytic activity is 120 kg-polyethylene / (gTi / h / ethylene pressure (atm)).

[Comparative Examples 1-6]

Tape Making by Discontinuous Method

The ultra-high molecular weight polyethylene powder obtained in Preparation Example 2 is shown in Table 1 below the maximum draw ratio and tensile strength obtained by compression, roller stretching and subsequent stretching. Compression was performed at a pressure of about 400 MPa on a 100 mm × 100 mm size plate.

In Comparative Example 1, after stretching at 25 ° C., the drawing was attempted without the roller drawing, but the drawing was impossible. In Comparative Example 2, a part of the compressed material in Comparative Example 1 was cut into a width of 10 mm and compressed (shear compression occurred) under a 400 MPa pressure, followed by stretching. In Comparative Example 3, the result was obtained by compressing at 125 ° C. In the comparative example 4, the compressed object in the comparative example 1 was extended after repeating roller stretching under the roller which consisted of two rollers. In Comparative Example 5, the compressed product obtained by shear compression in Comparative Example 2 was stretched after roller stretching. In Comparative Example 6, the compressed product in Comparative Example 3 was stretched after roller stretching.

The effective draw ratio at the time of roller stretching in Comparative Examples 4 to 6 is the length change ratio before and after roller stretching. In comparison, 1 to 6 were all discontinuous processes for obtaining high strength materials, but the effect of compression temperature and repetition was negligible, and it was found that roller drawing played an important role in improving draw ratio and physical properties.

TABLE 1

Maximum draw ratio and strength according to compression and drawing method (discontinuous process)

Example 1

Tape production by continuous roller rolling

In the present embodiment, the ultra-high molecular weight polyethylene powder obtained in Preparation Example 2 was subjected to compression and roller stretching of powdery ultra-high molecular weight polyethylene at the same time using a compression device of the roller according to the present invention, and tape having a width of 20 mm and a thickness of 0.13 mm. Got it.

The temperature of the roller was maintained at 125 ° C., the pressure applied to the roller was 400 MPa, and the effective draw ratio was about 2.0. The obtained tape was cut to 4 mm width, and 20 specimens were drawn at 125 ° C .. As shown in Table 2 below, the average maximum draw ratio was 25. The final stretched tape was 19.8 tex (178.2 denier), tensile strength 2.3 GPa, It showed excellent physical properties of tensile modulus 120 GPa.

Tensile strength and tensile modulus were measured using an "Instron" tensile test instrument at a tensile rate of 50mm / min at 25 ℃. Tensile modulus was obtained using stress at 0.1% strain, and the cross-sectional area of each specimen was calculated by measuring the length and weight of the specimen and assuming density of 1g / cm ³ .

[Comparative Examples 7-9]

Change of Tape Manufacturing Conditions by Continuous Roller Rolling

In Comparative Examples 7-9, the temperature and the pressure at the time of roller drawing were changed in the case of Example 1. Increasing the roller temperature or changing the pressure both reduced the maximum draw ratio or caused cutting. Maximum draw ratio refers to the maximum value that can occur with initial temperature and pressure changes.

TABLE 2

Maximum draw ratio and physical property change with temperature and pressure change

[Comparative Examples 10-11]

Width change when cutting roller drawn tape

In Comparative Examples 10 and 11, the roller-stretched tapes were cut into widths of 15 mm and 1 mm as in Example 1, and 20 specimens were stretched at 125 ° C. As a result, in the case of wide width, the maximum draw ratio was reduced to 12 ~ 15, and some of the tapes were cut first (fibrillation) .In the case of narrow width of 1mm, the maximum draw ratio increased to 30. The variation in the maximum draw ratio of the three specimens was about 15.

EXAMPLES 2-5

Preparation of High Strength, High Elastic Polyethylene Materials

In Examples 2 to 5, tape-shaped ultrahigh molecular weight polyethylene having a width of 4 mm and a thickness of 0.13 mm obtained in Example 1 was compressed and stretched using a production apparatus according to the present invention to obtain a high strength, high elastic polyethylene material.

In Examples 2 to 5, in all cases, after the initial drawing by the roller at the primary drawing part, the secondary drawing was performed at the secondary drawing part consisting of two heated plates, and after winding the material thus drawn secondly The extension was repeated twice on two heated plates again hanging on the bobbin holder. Therefore, the final draw ratio is the product of the draw ratio at the time of primary drawing, the draw ratio at the time of second drawing, the draw ratio at the time of additional drawing, the draw ratio at the time of second additional drawing (total drawing ratio), and the effective draw ratio at the time of roller rolling (double). Obtained by multiplying, the temperature, draw ratio and final draw ratio, and tensile strength and tensile modulus of the final drawn material at each step are listed in Table 3 below.

TABLE 3

Final draw ratio and physical properties according to the change of drawing conditions

In Example 2, when the initial roller speed was 5 m / min, no breakage occurred and a final draw ratio of 60 was obtained. The tensile strength and modulus of the final stretched material were 3GPa and 130 GPa, respectively.

In Example 3, the initial roller speed was 1 m / min, and in this case, the final draw ratio and physical properties were slightly increased.

In Example 4, the initial roller speed was 10 m / min. In this case, the draw ratio in each step was lower than in the case of Example 2, the final draw ratio was 30, and the tensile strength and modulus were 2 GPa and 121 GPa, respectively. Decreased.

In Example 5, the initial roller speed was the same as in Example 2, but the drawing speed was increased twice as much as in Example 2 during the second additional stretching. As a result, the draw ratio in the secondary weight and draw was reduced, resulting in a reduction in the final draw ratio and physical properties.

In Comparative Example 12, the drawing temperature was equalized to 130 ° C. during the primary and secondary stretching, and the draw ratio was decreased during the secondary stretching, and breakage occurred during additional stretching. In Comparative Example 13, the stretching temperature was 137, respectively. As a result of being unfamiliar with ℃, breakage occurred.

In Comparative Example 14, the temperature at the time of the second additional stretching was 150 ° C. and 152 ° C., respectively. In this case, the draw ratio increased by about four times, but showed a sharp decrease in physical properties.

In Comparative Examples 15 and 16, as a result of increasing the draw ratio during the primary drawing, breakage occurred immediately.

Finally, Table 4 shows the physical properties of the various ultrahigh molecular weight polyethylene fibers prepared and commercialized by the gel spinning method described on page 220 of the Fiber Reinforcements for Composite Materials (ARBunsell, published by Elsevier, 1988) and obtained in Example 2 of the present invention. The physical properties of the materials are compared.

As shown in Table 4, it can be seen that the tensile strength and elastic modulus of the polyethylene fiber produced by the manufacturing process according to the present invention is equivalent or superior to that obtained by the gel spinning method.

TABLE 4

Comparison of Physical Properties of Polyethylene Fibers Prepared by Gel Spinning Method and the Present Invention

As described above, the high-strength, high-elasticity polyethylene material manufacturing process according to the present invention does not use an organic solvent, so it is environmentally friendly and can produce a high-strength, high-elasticity polyethylene material that is continuous and excellent in physical properties without being cut during the work process. Can be.

Claims (9)

Titanium-containing liquid component (Ti (OR) nX _4-n ), where R is an alkyl, aryl or alalkyl group having 1 to 20 carbon atoms, X is halogen, n is 0-4 Water), an organoaluminum compound (R ₃ Al or R ₂ AlOR, where R is an alkyl group, an aryl group or an alalkyl group having 1 to 20 carbon atoms), a halogenated organoaluminum compound (R ₃ AlX, RAlX ₂ , RAl (OR) X, Or R ₃ Al ₂ X ₃ , wherein R is an alkyl group having 1 to 20 carbon atoms, an aryl group or an alkyl group, X is a halogen), and an ether organic compound (R'OR ', where R' is an alkyl group having 2 to 7 carbon atoms) And a homogeneous catalyst system consisting of a liquid component containing magnesium uniformly obtained by reacting metal-magnesium with an organoaluminum compound and a halogenated hydrocarbon, at a temperature of 0 to 9 ° C. and an atmospheric pressure of 0.7 to 3 in a hydrocarbon solvent. Prepared by polymerizing ethylene gas, the intrinsic viscosity is 10 to 40 dl in 135 ° C decalin solution compressing and stretching the ultra high molecular weight polyethylene powder, which is / g, into a roller having a stepped groove maintained at a pressure of 200 to 1000 MPa and maintained at 80 to 135 ° C., and conveying the same; Passing the compressed and stretched resin through a plurality of heated rollers to first draw at a draw ratio of 1.1 to 10 at 110 to 140 ° C; Secondly stretching the primary stretched resin at a draw ratio of 1.1 to 15 using 1 to 8 heated plates maintained at 115 to 150 ° C; And A process for producing a high strength, high elastic polyethylene material comprising the step of winding a secondary stretched resin. The process of claim 1, wherein the first and second stretching steps are repeated. 2. The process of claim 1, wherein the method further comprises constructing and extending the bobbin holder after the winding step. The process of claim 1, wherein the method further comprises a splitting step for adjusting the width and number of strands of the compact after the compacting step. The process of claim 1, wherein the roller is heated electrically or with fruit oil. The process for producing a high strength, high elastic polyethylene material according to claim 1, wherein the material is fibrous, film, or sheet. The method of claim 1, wherein the surface temperature of the plate is controlled 3 to 8 parts independently. The process of claim 1 wherein the plate has a convex surface to enhance contact with the polyethylene material. The process for producing a high strength, high elastic polyethylene material according to claim 1, wherein the total operation ratio of the polyethylene material is 10 to 150.