JPS59232123A - Production of solution of super-molecular weight polyethylene - Google Patents

Abstract

PURPOSE:To obtain a highly concentrated homogeneous solution of super-MW PE, by heating a specified super-MW PE and a solvent under agitation to wet the PE with the solvent and further heating the mixture under agitation. CONSTITUTION:100ptswt. super-MW PE (A) of an intrinsic viscosity of 5-30dl/g and 25-2,000ptswt. solvent (B) in which component A is soluble (e.g., n-nonane) are mixed together for at least 5min while the mixture is being heated so that it falls within a temperature range of from the lowest wetting temperature of the mixed system of components A and B to the m.p. of component A to wet component A with component B, and the mixture is heated under agitation to a temperature higher than the m.p. of component A to form a solution. EFFECT:It is possible to obtain a super-MW PE solution excellent in storage stability and moldability. USE:Filaments, tapes, and films.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a homogeneously dissolved ultra-high molecular weight polyethylene solution.

Ultra-high molecular weight polyethylene is superior to general-purpose polyethylene in impact resistance, abrasion resistance, chemical resistance, σ1 tensile strength, etc., and its use as an engineering plastic is expanding.

And since ultra-high molecular weight polyethylene has a much higher molecular weight than general-purpose polyethylene, (if it can be highly oriented, it may be possible to obtain a stretched product with higher strength and higher elasticity than ever before, However, since ultra-high molecular weight polyethylene has an extremely high melt viscosity compared to general-purpose polyethylene, it is almost impossible to extrude it using normal methods, and it is also difficult to make it highly oriented by stretching it. The current situation is that this is not possible.

On the other hand, as a method for drawing high-density polyethylene monofilaments at a high magnification, an additive with a high boiling point higher than the melting point of polyethylene is added at 20 to 15
The fluidity is improved by coexisting within a range of 0%, and a primary fibrous material is formed from the obtained high concentration dispersion, and then an amount equivalent to 5 to 20% of additives is added to the spun yarn. 3~3 to the original length with improved stretchability while retaining
A method of hot stretching 15 times (Japanese Patent Publication No. 37-9765) is known, but even if such a method is applied to ultra-high molecular weight polyethylene, as mentioned above, the molecular weight is much higher than that of general-purpose polyethylene. It is extremely poorly soluble in solvents, and even if ultra-high molecular weight polyethylene is simply added to a solvent and heated to raise the temperature, a uniform solution cannot be obtained because some portions are partially dissolved. Perhaps for this reason, as seen in the method of JP-A-56-15408, which proposes a method for producing high-elasticity and high-strength filaments from ultra-high molecular weight polyethylene solutions, it is generally stated that 1 to 50% by weight of Although it is said that a solution is used, in the example, only a method using a solution with a very low concentration of about 8% by weight at most, and 3% by weight for those with a molecular weight of 1 million or more is disclosed, and it is difficult to put it into practical use. In the treatment of large amounts of solvent,
Because of problems such as productivity, it is desired to obtain a highly concentrated solution of ultra-high molecular weight polyethylene'.

From this point of view, the present inventors have discovered that uniformly dissolved 1
As a result of various studies to develop a method for producing a highly concentrated solution of ultra-high molecular weight polyethylene, we found that by using a solvent that can dissolve ultra-high molecular weight polyethylene, heating and mixing the polyethylene with such a solvent, and increasing the melting point of the polyethylene. It has been found that a highly concentrated and uniform ultra-high molecular weight polyethylene solution can be produced by further heating and stirring after wetting at a specific temperature below 100 mL, and has led to the completion of the present invention.

That is, in the present invention, the intrinsic viscosity [η] is at least 5 dl.
/g or more ultra-high molecular weight polyethylene (4:+o.

Parts by weight and the polyethylene (solvent (B) capable of dissolving N:
After heating while mixing 25 parts by weight or more of ultra-high molecular weight polyethylene (Al and solvent (B)) at a temperature above the low-temperature wet treatment temperature of the mixed system of ultra-high molecular weight polyethylene (Al and solvent (B)) and below the melting point of the ultra-high molecular weight polyethylene, The present invention provides a method for producing a highly concentrated and uniform ultra-high molecular weight polyethylene solution, which is characterized by heating and stirring.

Ultra-high molecular weight polyethylene (10) used in the method of the present invention has an intrinsic viscosity [η] of 5 at 135°C in decalin solvent.
d#/g or more, preferably in the range of 7 to 30 dA/g. [η] is 5dj? If it is less than /g, it is easy to dissolve, but there is a tendency that a drawn product with excellent tensile strength cannot be obtained even if it is stretched. On the other hand, the upper limit of [η] is not particularly limited, but if it exceeds 30 dl/g, it is necessary to make an extremely thin solution in order to obtain a low viscosity solution, and there are few practical advantages. Such ultra-high molecular weight polyethylene is
Ethylene or ethylene and small amounts of other α-olefins, such as propylene, 1-butene, 4-methy)v-1-
Among the polyethylenes obtained by polymerizing pentene\1-hexene etc. by so-called Ziegler polymerization, it has a much higher molecular weight.

The melting point of the ultra-high molecular weight polyethylene in the present invention is AS
According to TM D 3417, Differential Scanning Calorimeter (DSC)
) is the value measured by

The solvent CB) used in the method of the present invention is a solvent that can dissolve the ultra-high molecular weight polyethylene (A), and preferably has a boiling point higher than the melting point of the polyethylene (A), more preferably higher than the melting point +20°C. It is a solvent with

Specifically, such solvent (B) includes n-nonane,
n-decane, n-undecane, n-dodecane, n-tetradecane, n-octadecane, liquid paraffin, aliphatic hydrocarbon solvents such as kerosene, xylene, naphthalene, tetralin, butylbenzene, p-cymene, cyclohexylbenzene, Diethylbenzene, pentylbenzene, dodecylbenzene-bicyclohexyl, decalin,
Aromatic hydrocarbon solvents such as methylnaphthalene and ethylnaphthalene or their hydrogenated derivatives, Ll, 2,2-te)-7chloroethane, pentachloroethane, hexachloroethane, 1,213-)dichloropropane, dichlorobenzene, +, Examples include 2.4-trichlorobenzene, bromobenzene, and other non-rogenated hydrocarbon solvents, paraffinic process oils, naphthenic process oils, aromatic process oils, and other mineral oils.

The method of the present invention comprises the ultra-high molecular weight polyethylene (~:1
00 parts by weight and 725 parts by weight or more, preferably 30 to 2000 parts by weight, of the solvent (B) are mixed and heated to a temperature higher than or equal to the low-temperature wet treatment temperature of the mixed system of ultra-high molecular weight polyethylene (A) and the solvent (13+). This is a method of producing a highly concentrated and uniform solution by moistening ultra-high molecular weight polyethylene at a temperature below the melting point of polyethylene (10%) and then heating and stirring.

Even if the amount of the solvent (B) is less than 25 parts by weight, it is possible to produce a solution by this method, but the resulting solution has a high viscosity and has little effect on improving extrusion moldability or stretchability. On the other hand, although the upper limit is not particularly limited, if it exceeds 2000 parts by weight, the concentration is too low to be practical.

Heating is performed while mixing ultra-high molecular weight polyethylene (7111) and solvent (B) within the above range, but when heating, be careful of the temperature of the mixing system and be sure to
and solvent (l) in a low temperature wet treatment temperature range or higher than the melting point of ultra-high molecular weight polyethylene (chrysanthemum),
Ultra-high molecular weight polyethylene (Ultra-high molecular weight polyethylene (A) powder or particles must be moistened. If the heating rate is increased during melting and heated above the melting point without waiting for the ultra-high molecular weight polyethylene (A) to become wet, it will not dissolve in the mixed system. Furthermore, it is not possible to obtain a homogeneous solution because the undissolved portion once formed does not disappear even after long-term heating and stirring.The mixing system can be heated using various known methods such as electric heating, oil, steam, and dielectric heating. It can be done.

The low-temperature wet treatment temperature in the present invention is to mix ultra-high molecular weight polyethylene (~IOg and 100 ml of solvent (B),
80.90.100.110.After stirring for 15 minutes at each treatment temperature of 120 and 130 °C, it was allowed to cool to room temperature, and then solid-liquid separation was performed by decantation, and the weight of the solid material (WE) is measured, and the solvent content fraction (
8%), S (%) = CVJ -10)/WX +'OO Next, from the relationship between the solvent content fraction and the processing temperature, find the temperature at which the solvent content fraction becomes 70%, and calculate that temperature. The temperature was set as a low-temperature wet treatment temperature.

The completion of wetting of ultra-high molecular weight polyethylene (A) is usually determined by visual inspection, since once the ultra-high molecular weight polyethylene (At) powder or particles become wet, the morphology of the mixture with the solvent changes significantly. It can be determined by observing.The change in morphology that indicates the end of wetting differs slightly depending on the concentration.For example, at a concentration of about 5 to 20%, the whole becomes gruel-like, the viscosity increases suddenly, and the concentration changes slightly. If it exceeds 30%, most of the solvent CB) will be contained in the powder or particles of the ultra-high molecular weight polyethylene (A), resulting in a fried egg-like appearance. The completion time of wetting differs somewhat depending on the type of solvent (B) used, but complete wetting can be achieved by keeping the temperature at a predetermined temperature above the low temperature wetting treatment temperature or below the melting point for at least 5 minutes, preferably for 10 minutes or more. In practice, a uniform solution can be obtained by controlling the temperature of the mixed system without observing the state of the mixed system of ultra-high molecular weight polyethylene (A) and solvent (B) one by one. However, the mixing tank is not necessarily limited to a mixing tank made of glass or a mixing tank provided with a viewing window, etc., and various mixing tanks such as metal and ceramic can be used.

÷ Ultra-high molecular weight Borie ≠ Ren (Once wetting of 70 is completed,
A homogeneous solution can be obtained by heating and stirring. The heating temperature after the completion of the wetting is higher than the melting point of the ultra-high molecular weight polyethylene (~, but when the ultra-high molecular weight polyethylene is wetted with the solvent (B), the melting point decreases, so
Actually, it is sufficient to heat the mixture to a temperature higher than the melting point of the solvent/ultra-high molecular weight polyethylene mixed system.

Further, the heating after the completion of the wetting may be continued after the completion of the wetting, but once the ultra-high molecular weight polyethylene is moistened with the solvent, it may be cooled to room temperature and solidified while still containing the solvent. A homogeneous solution can be obtained by heating and stirring to a temperature above the melting point of the solvent-ultra-high molecular weight polyethylene mixed system, so during heating, the solution is again allowed to stay at a temperature above the low-temperature wet treatment temperature or below the melting point of the ultra-high molecular weight polyethylene. It is not necessary, and the mixture can be immediately heated to a temperature higher than the melting point of the mixed system.

The ultra-high molecular weight polyethylene used in the present invention (N includes heat-resistant stabilizers, weather-resistant stabilizers,
Various additives, such as pigments, dyes, lubricants, gelling agents, and inorganic fillers, which are usually added to polyolefins, may be blended.

The solution of ultra-high molecular weight polyethylene obtained by the method of the present invention has a higher concentration than the solution obtained by the conventional method, so the amount of solvent used can be reduced, productivity is improved, and Since the viscosity is not extremely low,
It also has the advantage that the solution can be sufficiently transported using a common screw extruder or the like, and continuous extrusion using the solution is extremely easy.

As mentioned above, the solution of ultra-high molecular weight polyethylene obtained by the method of the present invention has good storage stability and good moldability once moistened, so it can be extruded into filaments, tapes, or films. By stretching, it can be used as a high-elasticity, high-strength filament, tape, or film in addition to the conventional fields of drawn yarn, tape, or film, and also as a reinforcing material.

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples as long as the gist of the present invention is not exceeded.

Example 1 <Determination of low-temperature wet treatment temperature> Powder of ultra-high molecular weight polyethylene with an intrinsic viscosity [η] of 171/g and a melting point of 142°C (trade name: Hi-Zex Mi IJ-ON 240M manufactured by Mitsui Petrochemical Industries, Ltd.) ) 10 each
g and decalin (boiling point: 190°C) each +00m6, 80.90.100, 140.120 and 150
After stirring for 15 minutes at each treatment temperature of 'C, let it cool to room temperature, then remove decalin by decantation, measure the weight (wg) of each solid, and use the following formula to calculate the solvent content. The fraction (S%) was calculated.

S (%) = (w -10)/WX I 00 Next, the relationship between the solvent content fraction at each processing temperature and each processing temperature is
A graph was drawn as shown in the figure, and the temperature at which the solvent content fraction became 70% was determined to be 105°C, and this temperature was taken as the low-temperature wet treatment temperature for the ultra-high molecular weight polyethylene-decalin system.

<Production of ultra-high molecular weight polyethylene solution> After putting 10 g of the ultra-high molecular weight polyethylene and decalin: IDD++J into a glass beaker, press a to raise the temperature of the system to 110°.
The ultra-high molecular weight polyethylene powder was heated to C and kept at that temperature to moisten the ultra-high molecular weight polyethylene powder.

As we continued to observe the situation in the prefecture, we found that after about 6 minutes at 110°C, it turned into a viscous slurry-like suspension and wetting was completed. Then, the temperature of the system was heated to +60°C and stirring was continued, and after about 5 minutes, a transparent solution was obtained, and an ultra-high molecular weight polyethylene solution was obtained.Example 2 Amount of ultra-high molecular weight polyethylene of Example 1 When the temperature of the system was maintained at 100°C and stirring was continued in the same manner as in Example 1 using 100 g of The wetting process was completed. Then the temperature of the system was increased to 16
When heated to 0°C and continued stirring, the solution became transparent and homogeneous after about 6 minutes, and an ultra-high molecular weight polyethylene solution was obtained.

Comparative Example 1 After putting 10 g of ultra-high molecular weight polyethylene used in Example 1 and 100 mA of decalin into a glass container, they were rapidly heated to 160°C while stirring. and continued stirring. However, even after 6 minutes had passed after reaching this temperature, a solution portion with a dilute concentration than the predetermined concentration and a molten mass of undissolved polyethylene powder were observed in the system. Even if stirring was continued for an additional 60 minutes, no homogenization due to dissolution of the molten polyethylene mass occurred.

Example 3.4 After putting 100 g of the ultra-high molecular weight polyethylene used in Example 1 and 200 ml of decalin into a glass container, the temperature of the system was heated to 110 °C while stirring, and the temperature was maintained at Wetting of high molecular weight polyethylene powder was carried out. The condition inside the system was continuously observed, and after about 10 minutes at 110°C, it changed to a fried egg shape and the moistening was completed. Next, after cooling the system to room temperature, remove the sample from the system by about 5 m.
The melting point of the ultra-high molecular weight polyethylene-decalin system was measured using DSC and found to be 120°C.

The yarn sample was then divided into two parts and one system was stirred for 16 hours.
When rapidly heated to 0°C, it took about 2 hours to reach that temperature.
After a few minutes, the system turned into a clear, homogeneous solution.

When the remaining system was rapidly heated to 135° C. in the same manner, it turned into a transparent and homogeneous solution after about 10 minutes.

<Evaluation of moldability> In order to evaluate the fluidity of the solutions obtained in Examples 1 to 3, melt flow rate) (MFR: ASTM D123
8, but the load was 20 kg and the temperature was 160°C)
The MF of ultra-high molecular weight polyethylene powder was measured.
R is less than iX+Og/+0m1n, whereas Example 1: 5oog/l[]min, Example 2:
0.05g/iDmin, Example 3: 2g/
A value of I Qmin was obtained, indicating that the solution had good fluidity.

Reference Example Using the same polyethylene and solvent as in Example 1, an ultra-high molecular weight polyethylene solution having a polymer concentration of 10% by weight was obtained in the same manner as in Example 1. Next, this solution was spun at 130°C using a spinning die with a spinning diameter of 1-0 mm,
The wet fibers were passed through an acetone bath maintained at 20°C and cooled to solidify. The cooled wet fibers, which had a gel appearance and a thickness of 1.8 mm, were then passed through a tubular open tube heated to 120° C. and drawn with a pair of godet rolls at various draw ratios. The table shows the elastic modulus and strength at each stretching ratio.

It is clear from the table that drawn fibers with high elasticity and high strength can be easily produced from the solutions of the present invention.

In the table, the elastic modulus and strength are measured using Instron universal testing machine 112.
Measurement was performed at room temperature (23°C) using Model 3 (manufactured by Instron). At this time, the sample length between the clamps is 100m.
m and σ [Tensioning speed was 100 mm/min.

However, the elastic modulus was calculated using stress at 2% strain.

The fiber cross-sectional area required for calculation is the density of polyethylene, Q,
It was determined by measuring the weight and length of the fiber as 96g/Qn'.

[Brief explanation of the drawing]

FIG. 1 shows the relationship between the solvent content fraction of the ultra-high molecular weight polyethylene-decalin system and the treatment temperature. Applicant: Director of the Agency of Industrial Science and Technology Hirobu Kawata Applicant: Mitsui Petrochemical Industries Co., Ltd. Agent: Kazutaka Yamaguchi 1. Amendment to Figure Processing Temperature Procedures February 4, 1980 Commissioner of the Japan Patent Office Manabu Shiga 1. Indication of the case 1988 Patent Application No. 106637 2, Title of the invention: Process for producing ultra-high molecular weight polyethylene solution 3, Relationship to the amended case Patent applicant: 3-1 (114) Kasumigaseki-chome, Chiyoda-ku, Tokyo Director of the Agency of Industrial Science and Technology Hirobe Kawata 3-2-5 Kasumigaseki, Chiyoda-ku, Tokyo (588) Mitsui Petrochemical Industries Co., Ltd. Representative: Seiki Nakano 4, Designated Agent: 1-4 Higashi-chome, Yatabe-cho, Tsukuba-gun, Ibaraki Prefecture, Institute of Industrial Science and Technology, Textile and Polymer Materials Research Director Taisho Oka 15, sub-agent (designated agent) 3-2-5-6 Kasumigaseki, Chiyoda-ku, Tokyo; agent (for Mitsui Petrochemical Industries, Ltd.) 3-chome Kasumigaseki, Chiyoda-ku, Tokyo. No. 2-5 Mitsui Petrochemical Industries Co., Ltd. (7049) Yamaguchi Japanese Telephone
Tokyo 580-2019 7, Date of amendment order (i) Voluntary amendment 8, Detailed description of the invention column 9 of the specification subject to amendment, Contents of amendment (1) “Heating and stirring” on page 4, line 12 of the specification There is, ``
``Heating and stirring'' is corrected. (2) On page 5, line 12 of the specification, rD 3417J is corrected to rD 3418J. (3) On page 9, line 1 of the specification, it says “r30%” is 120%.
” he corrected. (4) On page 11, line 19 of the specification, "142°C" should be amended to "134°C." (5) On page 13 of the specification, line 9, “100°C” and Al,
Correct it to "120℃". (6) On page 14, line 17 of the specification, "120°C" is amended to "112°C."that's all

Claims (1)

[Claims] (1) While mixing 400 parts by weight of ultra-high molecular weight polyethylene (A) having an intrinsic viscosity [η] of at least 5 de/g and 25 parts by weight or more of a solvent (B) capable of dissolving the polyethylene (υ), Heating, ultra-high molecular weight polyethylene (~
A method for producing an ultra-high molecular weight polyethylene solution, which comprises moistening a mixed system of and a solvent (B) at a temperature above the low-temperature wet treatment temperature and below the melting point of the ultra-high molecular weight polyethylene (A), and then further heating and stirring. .