KR19990081461A - Manufacturing process of high strength, high elasticity polyethylene material - Google Patents

Abstract

The present invention relates to a process for producing a high strength, high-elasticity polyethylene material by processing ultra high molecular weight polyethylene (UHMWPE) at a temperature not higher than the melting point, And feeding the resultant to a formed roller so as to perform compression transfer; Passing the compressed resin through a plurality of heated rollers and firstly stretching at a temperature of 110 to 140 캜 at a stretching ratio of 1.1 to 10; Secondarily stretching the primary stretched resin at a stretching ratio of 1.1 to 15 using at least one heated plate maintained at 115 to 150 캜; And a step of winding up the secondary stretched resin. The present invention also relates to a process for producing a high-strength and highly elastic polyethylene material.

Description

Manufacturing process of high strength, high elasticity polyethylene material

The present invention relates to a process for producing a high strength, high-elasticity polyethylene material by processing an ultrahigh molecular weight polyethylene (UHMWPE) at a melting point or lower. More particularly, the present invention relates to an apparatus using polyethylene resin Stretchable polyethylene fibers, films, sheets and the like by continuously advancing the stretchable polypropylene fibers through the continuous stretching process.

Generally, ultrahigh molecular weight polyethylene refers to polyethylene having a molecular weight of 10 ⁶ or more. Its major application is high-strength polyethylene fiber in which ultrahigh molecular weight polyethylene is highly oriented. It is excellent in absorbing impact energy, Also, since the density is very low, the non-elasticity and the non-elasticity ratio are excellent and the weight can be reduced.

At present, a high strength, high-elasticity polyethylene product manufactured by gel-spinning method in which a small amount of ultrahigh molecular weight polyethylene is put in an organic solvent such as decalin or paraffin, and the polymer solution is extruded and stretched and then the organic solvent is removed .

However, since the gel spinning method involves a complicated process of spinning and stretching a high-temperature low-concentration polyethylene solution, it has a high production cost and inherently contains environmental harmful factors related to the recovery of the organic solvent, Though its application is fairly limited.

Therefore, a solid-phase process in which only ultra-high-molecular-weight polyethylene is compressed and stretched at a temperature not higher than the melting point without using an organic solvent has been proposed and developed as a method for producing environmentally friendly and inexpensive ultrahigh molecular weight polyethylene products.

European Patent Publication No. EP253513A2 discloses a method of processing ultrahigh molecular weight polyethylene without using an organic solvent by extruding powdery polyethylene into a cylinder at a melting point or lower and then stretching it. However, in the two-step process in which the solid-state extrusion process and the stretching process are separated as described above, it is impossible to continuously produce a fiber or tape-like product, and the solid-state extrusion rate is too low at 0.24 cm / I can not.

European Patent Publication No. EP 374785A1 also discloses a device comprising two belts which are driven and circulated by interconnecting rollers in such a way that ultra-high molecular weight polyethylene is processed without using organic solvents, and a powdery polyethylene And then extruding the ultra high molecular weight polyethylene by compression molding at a melting point or lower. However, this method also has a problem that an installation cost is excessively required because a complicated and large circulating belt is used for simple pressing of the resin.

Accordingly, it is an object of the present invention to provide an eco-friendly manufacturing process for solving the above-mentioned problems, in which a powdery ultra-high molecular weight polyethylene is processed through a simple apparatus at a melting point or lower without using an organic solvent, A high-strength, high-elasticity polyethylene material.

In order to accomplish the above object, the present invention provides a process for producing a high-molecular-weight polyethylene powder, which comprises feeding a ultra-high molecular weight polyethylene powder into a roller having a stepped groove maintained at a pressure of 200 to 1000 MPa and 80 to 135 캜, Passing the compressed resin through a plurality of heated rollers and firstly stretching at a temperature of 110 to 140 캜 at a stretching ratio of 1.1 to 10; Secondarily stretching the primary stretched resin at a stretching ratio of 1.1 to 15 using at least one heated plate maintained at 115 to 150 캜; And winding the secondary elongated resin.

The process for producing a high-strength and high-elastic polyethylene material according to the present invention as described above eliminates many problems in the conventional problems, that is, productivity and production costs due to the production technique of compressing and stretching the polyethylene resin below the melting point. In addition, the compression and stretching equipment is simplified so that compression and stretching of the resin can be effected effectively, and high strength and high-elasticity polyethylene materials can be produced in an environmentally friendly manner by using no organic solvent.

1 is a perspective view schematically showing a roller of a compression part used in a process for manufacturing a high strength and high elasticity polyethylene material according to the present invention,

FIG. 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 showing a state in which a bobbin holder according to an embodiment of the present invention is added.

[Description of Reference Numerals]

1: raw material input part 2: compression part

3: The slitting part 4: The first finishing part

5: preheating part 6: secondary finishing part

7: winding section 8: bobbin holder

9: Extrusion roller

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

1 is a perspective view schematically showing a roller of a compression part of an apparatus for producing a high strength and high elasticity polyethylene material according to the present invention and FIG. 2 is a schematic view showing a process of manufacturing a high strength, high elasticity polyethylene material according to the present invention 3 is a process diagram schematically showing a state in which a bobbin holder according to an embodiment of the present invention is added.

In the drawing, reference numeral 1 denotes a raw material input portion, 2 denotes a compression portion, 3 denotes a slitting portion, 4 denotes a primary stretching portion, 5 denotes a preheating portion, 6 denotes a secondary stretching portion, 7 denotes a winding portion, 8 denotes a bobbin holder, Fig.

As shown in Fig. 1, the compression section 2 is constituted by two rollers 9 having stepped grooves formed so as to be engaged with each other. The inside of each of the rollers 9 can be heated to a predetermined temperature using an electric or thermal oil, and the driving speed of the roller 9 can be adjusted. The polyethylene resin in the powder state is passed between the two rollers 9 at a temperature not higher than the melting point, and at the same time, it is continuously compressed and stretched. Therefore, by adjusting the amount of resin to be injected, the pressure applied to the stepped groove portion of the roller, and the driving speed of the roller 9, the thickness and the degree of compression of the compressed product can be adjusted.

In general, the roller apparatus for plastic working is configured such that the two rollers 9 are rotated while being spaced apart from each other at a predetermined interval to obtain a compact having a constant thickness at a processing temperature equal to or higher than the melting point, A step groove is formed in each of the rollers to be engaged with each other at the time of rotation and the resin is allowed to pass through the resin at a temperature below the melting point so that the resin is stretched in the rotating direction while being compressed.

As shown in Fig. 2, the width and the number of strands are adjusted in the slitting portion 3 of the compact which has passed through the charging portion 1 and the compression portion 2 for supplying the resin. The compressed product that has passed through the slitting portion is subjected to initial stretching through a first stretching portion 4 composed of three or more compression rollers. Since each roller of the primary stretching section can adjust the rotational speed and temperature, the degree of stretching at the melting point or less can be controlled. The primary stretching part 4 includes a preheating part for the second elongation and a pressing roller for preventing slippage in the second elongation part. Is preheated in the preheating section (5), and then transferred to the second elongating section (6) which is a heated plate. The secondary stretching part (6) keeps the stretched product at a constant temperature through surface contact with the stretched product. The secondary stretching plate preferably has a somewhat convex surface in order to improve contact with the polyethylene material. Further, in the second elongation process, the surface temperature of the three or more portions can be independently controlled. The secondary stretching ratio can be adjusted as a ratio of the roller rotational speed of the preheating portion 5 with the pressing roller attached before and after the heated plate and the drawn product that has been drawn by the winding portion 7 is wound.

The preheating unit and the secondary stretching unit for the secondary stretching in the apparatus may be composed of a plurality of units as required. When the secondary stretching material is to be subjected to further stretching without addition of equipment, Further stretching can be performed by positioning the holder 8 before the preheating section 5 and repeating the stretching process.

A process for producing a high-strength and high-elasticity polyethylene material using the manufacturing apparatus of the present invention will now be described.

The ultrahigh molecular weight polyethylene resin used in the present invention is a polyolefin resin having a molecular weight of from 0 to 90 in a hydrocarbon solvent in the presence of a homogeneous catalyst composed of a liquid component containing titanium, an organoaluminum compound, a halogenated organoaluminum compound, an ether organic compound and a magnesium component. Lt; 0 > C and an atmospheric pressure (atm) of 0.7 to 3. The above-mentioned method was filed by the same applicant as " Method for producing ultrahigh molecular weight polyethylene " When ethylene gas is synthesized at room temperature by the above method, powdery polyethylene having an intrinsic viscosity of 10 to 40 dl / g can be obtained in a decalin solution at 135 ° C. The polyethylene powder obtained by the above method has a low specific gravity and a fine structure suitable for compression and stretching at a low temperature.

According to the present invention, the polyethylene powder is continuously compressed and stretched while passing through the rollers of the compression section 2 heated at a pressure of 200 to 1000 MPa and at 80 to 135 캜. At this time, if it is less than 200 MPa, compression is inadequate and stretching is difficult, and if it exceeds 1000 MPa, compression becomes uneven and defects in the compressed product increase. If the temperature is lower than 80 캜, the compressed product tends to be broken, so that the possibility of disconnection at the time of stretching is high. When the temperature exceeds 135 캜, melting of the resin occurs and solid-state processing becomes difficult.

This compact is initially drawn in the primary stretching part 4 composed of a plurality of heated rollers and is secondarily stretched in the plate of the heated secondary stretching part 6. The temperatures of the rollers of the first stretching portion and the plates of the second stretching portion are maintained at the melting point of the resin at about 110 to 140 DEG C and about 115 to 150 DEG C respectively and the stretching ratio is increased by slightly increasing the processing temperature as the stretching progresses, Thereby producing a highly elastic polyethylene material. Further, the stretching ratio can be performed to a desired extent by repeating the first stretching step and the second stretching step. The stretching ratio in the first and second stretching is preferably 1.1 to 10. When the stretching ratio is less than 1.1, the stretching is not performed and the strength is not increased. When the stretching ratio exceeds 10, the stretching is difficult in the second stretching. The stretching ratio is preferably from 1.1 to 15, but if the stretching ratio is less than 1.1, the stretching is insufficient. If the stretching ratio is more than 15, the stretching of the fibers is difficult. The total grain size ratio is preferably from 10 to 150, and if it is less than 10, the fiber strength is low due to insufficient stretching, and if it exceeds 150, the possibility of cutting the fiber is high, and continuous operation is difficult.

The shape of the material thus produced may be a fibrous shape, a film shape, or a sheet shape, and when it is fibrous, its thickness is 0.2 mm or less and its 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 component containing magnesium

15 g of metal-magnesium, 60 ml of n-heptane, 5 ml of 1-chlorobutane, and 6 mmol of triethyl aluminum are mixed in a glass flask vessel under a nitrogen atmosphere. The temperature is raised above 98 ° C (boiling point of heptane) and stirred for 20 minutes. Thereafter, a solution of 54 g of 1-chlorobutane dissolved in normal-heptane (440 ml) in a dropwise manner is added for 1 hour. After maintaining the temperature for 2 hours, 0.159 mol of triethylaluminum is added. Thereafter, it is heated for 1 hour. After filtering the precipitate, the remaining solution will contain approximately 7.4 g / l of magnesium, which is used for ethylene synthesis.

Production Example 2

In a 300 ml reactor, 200 ml of normal-heptane, 0.12 ml of triethylaluminum (1M heptane solution), 1.76 ml of the magnesium-organic solution prepared in Preparation Example 1, 1.8 mg of tetrahydrofuran, 0.128 g Of diethyl aluminum chloride, and 0.58 mg of titanium tetrachloride, and the pressure of the ethylene gas is set to 1 atm. The reaction is carried out for 1 hour while maintaining the temperature at 25 캜 and the gas pressure at 1 atm to synthesize ultrahigh molecular weight ethylene having a viscosity of 15.4 (decalin at 135 캜). At this time, the catalytic activity is 120 kg-polyethylene / (gTi / h / ethylene pressure (atm)).

Comparative Examples 1 to 6

Manufacture of tapes by non-continuous method

Table 1 shows the maximum draw ratio and tensile strength obtained by compression, roller drawing and subsequent drawing of the ultrahigh molecular weight polyethylene powder obtained in Production Example 2. Compression was carried out at a pressure of about 400 MPa in a 100 mm x 100 mm sized plate.

In Comparative Example 1, stretching was attempted without roller elongation after compression at 25 DEG C, but elongation was impossible. In Comparative Example 2, a part of the compressed product of Comparative Example 1 was cut to a width of 10 mm and then compressed (under shear compression) under a pressure of 400 MPa and stretched, and Comparative Example 3 was obtained after compression at 125 ° C. In Comparative Example 4, the compact in Comparative Example 1 was stretched by repeated rollers under a roller composed of two rollers, followed by stretching. In Comparative Example 5, the compact obtained by shear compression in Comparative Example 2 was rolled and then drawn. In Comparative Example 6, the compact in Comparative Example 3 was rolled and then drawn.

The effective elongation ratios in the roller elongation in Comparative Examples 4 to 6 are the length change ratios before and after roller elongation. Comparative Examples 1 to 6 were all methods for obtaining a high-strength material in a discontinuous process, but the effects of compression temperature and repetition were small, and roller stretching plays a very important role in improving the stretching ratio and physical properties.

Maximum stretch ratio and strength according to compression and stretching method (non-continuous process) Compression and stretching methods Compression temperature (℃) Effective stretching ratio at roller stretching Maximum draw ratio (at 125 占 폚) Tensile Strength (GPa) lowest Best Comparative Example 1 Cold compression 25 Comparative Example 2 Cold compression + shear compression 25 24 0.81 0.91 Comparative Example 3 High temperature compression 125 45 0.94 1.12 Comparative Example 4 Cold Compression + Roller Stretch 25 5.6 24 1.75 1.88 Comparative Example 5 Cold Compression + Shear Compression + Roller Stretching 25 3.4 22 1.70 1.99 Comparative Example 6 High temperature compression + roller stretching 125 3.9 20 1.27 1.69

Example 1

Tape production by continuous roller rolling

According to the present invention, the ultrahigh molecular weight polyethylene obtained in Production Example 2 was simultaneously subjected to compression and roller stretching in the powdery ultra-high molecular weight polyethylene by a production apparatus using a pressing force of a roller to produce a tape having a width of 20 mm and a thickness of 0.13 mm .

The temperature of the roller was maintained at 125 DEG C, and the applied pressure to the roller was 400 MPa, and the effective stretching ratio was about 2.0. The resulting tape was cut to a width of 4 mm, and 20 specimens were stretched at 125 ° C. As shown in Table 2, the average maximum stretching ratio was 25, the final stretched tape was 19.8 tex (178.2 denier), tensile strength was 2.3 GPa, Tensile modulus of 120 GPa.

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

Comparative Examples 7 to 9

Change of Tape Production Conditions by Continuous Roller Rolling

In Comparative Examples 7 to 9, the temperature and pressure at the time of roller stretching were changed in the case of Example 1. When the roller temperature was increased or the pressure was changed, the maximum draw ratio was decreased or the cutting occurred. The maximum draw ratio refers to the maximum value that can appear depending on the initial temperature and pressure change.

Change of maximum draw ratio and physical properties according to temperature and pressure change Roll temperature (캜) Roll pressure (MPa) Maximum draw ratio (at 125 占 폚) Tensile Strength (GPa) Modulus (GPa) Example 1 125 400 25 2.3 120 Comparative Example 7 140 400 2.3 0.7 15 Comparative Example 8 125 1000 Cutting occurrence Comparative Example 9 125 200 Cutting occurrence

Comparative Examples 10 to 11

Width change when cutting roller-stretched tape

In Comparative Examples 10 and 11, as in Example 1, the roller-stretched tapes were cut into widths of 15 mm and 1 mm, respectively, and twenty specimens were stretched at 125 ° C. As a result, when the width is wide, the maximum draw ratio is reduced to 12 to 15, and some of the tapes are first cut (fibrillated). When the width is narrowed to 1 mm, the maximum draw ratio is increased to 30, The maximum stretching ratio of three specimens was about 15, and the deviation increased.

Examples 2 to 5

Manufacture of high strength, high elasticity polyethylene materials

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

In all of Examples 2 to 5, after the initial stretching by the roller in the primary stretching portion, the secondary stretching was performed in the secondary stretching portion composed of the two heated plates, and after the secondary stretching material was wound The additional stretching was repeated twice on two heated plates by hanging on a bobbin holder. Therefore, the final stretching ratio is determined by multiplying the effective stretching ratio (twice) at the time of roller rolling by the product of the stretching ratio at the first stretching, the stretching ratio at the second stretching, the stretching ratio at the additional stretching, And the temperature at each step, the draw ratio and the final draw ratio, and the tensile strength and tensile modulus of the finally drawn material are shown in Table 3 below.

Final Drawing Ratio and Properties Based on Stretching Condition Change Examples and Comparative Examples Stretching step Initial roller speed (m / min) Stretching temperature (캜) Step-by-step stretching Final draw ratio Strength (GPa) Modulus (GPa) Roller device (first elongation) Plate 1 Plate 2 Roller device (first elongation) Plate 1 Plate 2 Room 2 1st and 2nd elongation 5 130 135 137 2.4 2.0 1.6 60 3.0 130 Additional stretching - - 140 143 - 1.7 1.45 2nd additional extension - - 148 150 - 1.4 1.13 Room 3 1st and 2nd elongation One 130 135 137 2.5 2.1 1.7 63.2 3.1 135 Additional stretching - - 140 143 - 1.6 1.4 2nd additional extension - - 148 150 - 1.4 1.3 Room 4 1st and 2nd elongation 10 130 135 137 2.3 1.9 1.55 30 2.0 121 Additional stretching - - 140 143 - 1.4 1.2 2nd additional extension - - 148 150 - 1.2 1.1 Room 5 1st and 2nd elongation 5 130 135 137 2.4 2.0 1.6 24 2.0 120 Additional stretching - - 140 143 - 1.2 1.1 2nd additional extension - - 148 150 - 1.1 1.1 Rain 12 1st and 2nd elongation 5 130 130 130 2.4 1.5 1.1 8 Additional stretching - - - - - cut - Rain 13 1st and 2nd elongation 5 130 135 137 2.4 2.0 1.6 17 Additional stretching - - 137 - - 1.1 cut Rain 14 1st and 2nd elongation 5 130 135 137 2.4 2.0 1.6 151.5 0.8 60 Additional stretching - - 140 143 - 1.7 1.45 2nd additional extension - - 150 152 - 2.0 2.0 Rain 15 1st and 2nd elongation 5 130 - - 4 cut - 8 Rain 16 1st and 2nd elongation 5 135 - - cut - - -

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

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

In Example 4, the initial roller speed was set to 10 m / min. In this case, the stretching ratio in each step was lower than that in Example 2, the final stretching ratio was 30, the tensile strength and modulus were 2 GPa and 121 GPa Respectively.

In Example 5, the initial roller speed was made the same as in Example 2, but the elongation speed was increased by two times as compared with Example 2 during the second additional elongation. As a result, the stretching ratio at the time of the secondary additional stretching was decreased, and the final stretching ratio and physical properties were reduced.

In Comparative Example 12, the stretching ratio at the time of the second elongation was decreased and the elongation at the time of the further elongation was cut. In Comparative Example 13, the elongation at the first elongation was 137 Lt; RTI ID = 0.0 > C, < / RTI >

In Comparative Example 14, the temperature for the second additional stretching was set at 150 캜 and 152 캜, respectively. In this case, the stretching ratio increased about four times, but the physical properties were sharply decreased.

In Comparative Examples 15 and 16, as a result of increasing the stretching ratio in the primary stretching, a break occurred immediately.

Finally, Table 4 shows the physical properties of various ultrahigh molecular weight polyethylene fibers produced and commercialized by the gel spinning method described in page 220 of Fiber Reinforcements for Composite Materials (edited by AR Bunsell, Elsevier, 1988) The physical properties of the materials are compared.

As shown in Table 4 below, it can be seen that the tensile strength and modulus of elasticity of the polyethylene fibers produced by the manufacturing process according to the present invention are equal or superior to those obtained by the gel spinning method.

Gel spinning and comparison of physical properties of the polyethylene fibers produced by the present invention Manufacturing method Tensile Strength (GPa) Modulus (GPa) Example 2 Continuous solid phase process 130 3.0 Spectra 900 (Allied) Gel spinning 119 2.6 Spectra 1000 (US Allied) Gel spinning 175 3.0 Dymeema (DSM Corporation) Gel spinning 50 to 125 2 to 3.5 Takmilon (Il Mitsui Oil Company) Gel spinning 60-100 1.5 to 3.5

As described above, the process for producing a high-strength and high-elastic polyethylene material according to the present invention does not use an organic solvent, so that a high-strength and high-elastic polyethylene material which is environmentally friendly and excellent in continuity and physical properties without being cut during a working process is manufactured .

Claims (10)

Feeding the ultrahigh molecular weight polyethylene powder into a stepped groove-forming roller maintained at a pressure of 200 to 1000 MPa and a temperature of 80 to 135 占 폚 to compress and transport; Passing the compressed resin through a plurality of heated rollers and firstly stretching at a temperature of 110 to 140 캜 at a stretching ratio of 1.1 to 10; Secondarily stretching the primary stretched resin at a stretching ratio of 1.1 to 15 using at least one heated plate maintained at 115 to 150 캜; And And a step of winding up the secondary stretched resin. The method of claim 1, wherein the first stretching step and the second stretching step are repeatedly performed. 2. The method of claim 1, wherein the method further comprises forming a bobbin holder after the winding step to further stretch. 2. The method of claim 1, wherein the method further comprises a step of slitting to adjust the width and strand count of the compact after the compacting step. The ultrahigh molecular weight polyethylene according to claim 1, wherein the ultrahigh molecular weight polyethylene comprises ethylene in a ratio of 1) a liquid component containing magnesium and aluminum, 2) a liquid component containing titanium, 3) an ether organic compound, and 4) (UHMWPE) having an intrinsic viscosity of 10 to 40 dl / g in a decalin solution at 135 占 폚 obtained by polymerization in the presence of a catalyst. 2. The method of claim 1, wherein the roller is heated electrically or by heat flow. The method of claim 1, wherein the material is a fiber, a film, or a sheet. The method of claim 1, wherein at least three portions of the surface temperature of the plate are independently controlled. The method of claim 1, wherein the plate has a somewhat convex surface to improve contact with the polyethylene material. The method of claim 1, wherein the total stretching ratio of the polyethylene material is 10 to 150.