JPH0277450A - Molecule orientated molded article of ultra-high-molecular-weight polyolefin base resin - Google Patents

Abstract

PURPOSE:To obtain the title molded article having excellent long-term heat stability and weather resistance without damaging tensile strength, etc., by blending an ultra-high-molecular-weight polyolefin with a specific amount of a metallic salt of higher fatty acid. CONSTITUTION:(A) 100 pts.wt. ultra-high-molecular-weight polyolefin having >=5dl/g, preferably 5-40dl/g intrinsic viscosity is blended with (B) 0.005-5 pts. wt., preferably 0.01-0.5 pt.wt. metallic salt of higher fatty acid (magnesium stearate), molded and drawn.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an ultra-high molecular weight polyolefin-based molecularly oriented molded article having excellent long-term heat resistance stability.

Technical background of the invention and its problems It is already known that a molecularly oriented molded article having high tensile strength and high tensile modulus can be obtained by forming an ultra-high molecular weight polyolefin into a fiber, tape, etc. and then stretching it. ing. For example, JP-A-56-15408 discloses a method of spinning a dilute solution of ultra-high molecular weight polyethylene and then drawing the resulting filament.

Further, JP-A-59-130313 discloses a method in which ultra-high molecular weight polyethylene and wax are melt-kneaded, a mixed material is extruded, the kneaded material is then cooled and solidified, and then stretched. Furthermore, JP-A-59-187614
The publication discloses a method in which the molten mixture is extruded and then passed through a draft, and then the molten mixture is cooled, solidified, and stretched.

Molecularly oriented molded products such as fibers and tapes made of ultra-high molecular weight polyolefins have high tensile strength and high tensile modulus, so they are used in applications that require particularly high quality. It may be used for long periods under atmospheric conditions. However, since molecularly oriented molded products made of ultra-high molecular weight polyolefins are essentially polyolefins, they easily deteriorate at high temperatures and have problems with long-term heat resistance stability, such as reduced tensile strength and tensile modulus. Ta. As a method for preventing such thermal deterioration of the ultra-high molecular weight polyolefin molecularly oriented molded article, there is a method of adding a heat-resistant stabilizer to the ultra-high molecular weight polyolefin. However, since ultra-high molecular weight polyolefin molecular alignment products are manufactured through a process in which the diluent is eluted using a solvent such as decalin as a heating medium during stretching of the ultra-high molecular weight polyolefin, ordinary heat-resistant stabilizers cannot be used together with the diluent. Since this stabilizer was eluted into the solvent, thermal deterioration of the ultra-high molecular weight polyolefin molecularly oriented molded article could not be sufficiently prevented.

Purpose of the Invention The present invention aims to solve the above-mentioned problems, and aims to provide ultra-high molecular weight polyolefin with long-term heat resistance stability that does not impair the inherent tensile strength, tensile modulus, etc. The purpose of the present invention is to provide an ultra-high molecular weight polyolefin-based molecularly oriented molded article with excellent properties.

Summary of the Invention The ultra-high molecular weight polyolefin-based molecularly oriented molded article according to the present invention contains (A) ultra-high molecular weight polyolefin, (B) metal salt of higher fatty acid = (A) 0 parts by weight of ultra-high molecular weight polyolefin. .005 to 5 parts by weight.

Since the ultra-high molecular weight polyolefin-based molecularly oriented molded article according to the present invention is composed of an ultra-high molecular weight polyolefin (A) and a specific amount of the stabilizer (B), it has long-term heat resistance stability. Excellent, maintains high tensile strength and high tensile modulus.

DETAILED DESCRIPTION OF THE INVENTION The ultra-high molecular weight polyolefin-based molecularly oriented molded article according to the present invention will be specifically described below.

The ultra-high molecular weight polyolefin-based molecularly oriented molded article according to the present invention contains an ultra-high molecular weight polyolefin (A) and a specific amount of the stabilizer (B).

The ultra-high molecular weight polyolefin-based molecularly oriented molded article according to the present invention can be produced by adding a diluent to the ultra-high molecular weight polyolefin composition containing the components (A) and (B).

First, the components constituting this ultra-high molecular weight polyolefin composition will be explained.

Ultra-high molecular weight polyolefin (A) Ultra-high molecular weight polyolefin (A), which is one component of the ultra-high molecular weight polyolefin composition, includes, for example, ethylene, propylene, 1-butene, ■-pentene, 1-hexene, ■
-octene, ■-decene, ■-dodecene, 4-methyl-
It consists of a homopolymer or copolymer of α-olefins such as 1-pentene and 3-methyl-1-pentene. Among these, ethylene homopolymers or ethylene and other α
-Olefins such as l-butene, l-pentene, -
Consists of octene, 4-methyl-1-pentene, etc.
Particularly preferred are copolymers containing ethylene as a main component.

135 of the ultra-high molecular weight polyolefin (A) as described above
The intrinsic viscosity [η] measured in °C decalin solvent is at least 5 dff/g, preferably from 5 to 40 dD/g. If the intrinsic viscosity [η] is less than 5 dfl/g, the resulting molecularly oriented molded product will not have sufficient tensile strength, while if it exceeds 40 dj7/g, it will tend to be difficult to mold the molecularly oriented molded product. I don't like it because of this.

Metal salt of higher fatty acid (B) The ultra-high molecular weight polyolefin composition, in addition to the above-mentioned ultra-high molecular weight polyolefin (A), is difficult to be eluted by the solvent used as a heating medium when stretching the ultra-high molecular weight polyolefin. It may also contain a metal salt (B) of a higher fatty acid.

Examples of metal salts of higher fatty acids include magnesium salts and calcium salts of higher fatty acids such as stearic acid, oleic acid, lauric acid, capric acid, arachidonic acid, palmitic acid, behenic acid, 12-hydroxystearic acid, ricinoleic acid, and montanic acid. , alkaline earth metal salts such as barium salts, alkali metal salts such as cadmium salts, zinc salts, lead salts, sodium salts, potassium salts, and lithium salts. Specifically, the following compounds are preferably used in terms of compatibility with ultra-high molecular weight polyolefins and elution resistance to the solvents listed in 1 above.

Magnesium stearate, magnesium laurate,
Magnesium palmitate, calcium stearate,
Calcium oleate, calcium laurate, barium stearate, barium oleate, barium laurate, barium arachidonate, barium behenate, zinc stearate, zinc oleate, zinc laurate, stearate, sodium stearate, valmitic acid Sodium, sodium laurate, potassium stearate, potassium laurate, calcium 12-hydroxystearate, calcium montanate, etc.

These metal salts of higher fatty acids may be used alone or in combination.

The higher fatty acid metal salt (B) as described above is 0.005 to 5 parts by weight, preferably 0.01 parts by weight, based on 100 parts by weight of the total weight of the ultra-high molecular weight polyolefin (A) and the diluent.
~0.5 parts by weight, more preferably 0.5 parts by weight. ．． 05-0.5
Used in parts by weight.

If the amount of the higher fatty acid metal salt (B) is less than 0.005 parts by weight based on 100 parts by weight of the total weight of the ultra-high molecular weight polyolefin (A) and the diluent, the residual amount in the polymer derived from the catalyst will be reduced. This is not preferable because chlorine absorption is insufficient and causes resin deterioration.On the other hand, if it exceeds 5 parts by weight,
This is undesirable because not only the cost of the stabilizer increases, but also the properties of the resin, such as tensile elongation, may be impaired.

Metal salts of higher fatty acids as described above have effects as lubricants, moldability improvers, and protective agents, so ultra-high molecular weight polyolefin compositions containing these metal salts have excellent moldability and are easy to use in molding machines, etc. Effective in preventing rust.

The ultra-high molecular weight polyolefin composition contains the above components (A
) and (B), additives that are usually added to polyolefins, such as heat stabilizers, weather stabilizers, pigments, dyes, lubricants, antistatic agents, etc., may be added within a range that does not impair the purpose of the present invention. It can be added with

Next, a method for producing an ultra-high molecular weight polyolefin-based molecularly oriented molded article according to the present invention will be explained.

When producing a molecularly oriented molded article from the above-mentioned ultra-high molecular weight polyolefin composition, a diluent is added to the composition.

As the diluent, a solvent for ultra-high molecular weight polyolefin or various waxes having dispersibility for ultra-high molecular weight polyolefin are used.

The solvent used as a diluent preferably has a boiling point higher than the melting point of the ultra-high molecular weight polyolefin, more preferably higher than the melting point +20°C.

Specifically, such solvents include n-nonane, n-
-dodecane, n-undecane, n-tetradecane, n-
Octadecane or liquid paraffin, aliphatic hydrocarbon solvents such as kerosene, xylene, naphthalene, tetralin,
Aromatic hydrocarbon solvents such as butylbenzene, p-cymene, cyclohexylbenzene, diethylbenzene, pentylbenzene, dodecylbenzene, bicyclohexyl, decalin, methylnaphthalene, ethylnaphthalene or their hydrogenated derivatives, 1,1,2.2- Tetrachloroethane, pentachloroethane, hexachloroethane, 1.2
．． 3-) 1 Chloropropane, dichlorobenzene, 1
, 2.4-Trichlorobenzene, halogenated hydrocarbon solvents such as bromobenzene, paraffinic process oil,
Examples include mineral oils such as naphthenic process oils and aromatic process oils.

Further, as the wax used as a diluent, an aliphatic hydrocarbon compound or a derivative thereof is used.

The aliphatic hydrocarbon compound is a paraffin wax mainly composed of a saturated aliphatic hydrocarbon compound, and usually has a molecular weight of 2,000 or less, preferably i,ooo or less, and more preferably 800 or less. Specifically, the following aliphatic hydrocarbon compounds are used.

N-alkanes with 22 or more carbon atoms such as tocosan, tricosane, tetracosane, and triacontane, or mixtures of these with lower n-alkanes as main components, so-called paraffin wax separated and refined from petroleum, ethylene or ethylene and other Heat-degraded polyethylene such as medium/low pressure polyethylene wax, high pressure polyethylene wax, ethylene copolymer wax, medium/low pressure polyethylene, high pressure polyethylene, etc., which are low molecular weight FFI polymers obtained by copolymerizing with α-olefin. Waxes whose molecular weight has been lowered by methods such as waxes and oxides of these waxes, oxidized waxes modified with maleic acid, waxes modified with maleic acid, etc.

Examples of aliphatic hydrocarbon compound derivatives include one or more, preferably one to two, particularly preferably one, carboxyl group or hydroxyl group at the terminal or inside of an aliphatic hydrocarbon group (alkyl group, alkenyl group). , a compound having a functional group such as a carbamoyl group, an ester group, a mercapto group, or a carbonyl group having 8 or more carbon atoms, preferably 12 to 50 carbon atoms, or a molecular weight of 130 to 2,000, preferably 200 to 800 fatty acids, fats family alcohol,
Fatty acid amides, fatty acid esters, aliphatic mercaptans,
Aliphatic aldehydes, aliphatic ketones, etc. are used. Specifically, the following compounds are used.

Fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and oleic acid, fatty alcohols such as lauryl alcohol, myristyl alcohol, cetyl alcohol, and stearyl alcohol, caprinamide, lauramide, palmitinamide, stearylamide, etc. fatty acid amides, fatty acid esters such as stearyl acetate, etc.

The diluent as described above is an ultra-high molecular weight polyolefin (A
) and in an amount such that it accounts for 97 to 20% by weight, preferably 85 to 40% by weight, based on the total weight of the diluent. If the amount of the diluent is less than 20% by weight, the melt viscosity will become too high, making melt mixing or melt molding difficult, and the surface of the molded product will be noticeably rough.
Moreover, it is not preferable because it tends to cause stretching breakage, etc.
If it exceeds % by weight, it is not preferable because it becomes difficult to cross-wire the melt and the molded product tends to have poor stretchability.

Melting crosstalk is generally 150~300℃, especially 170~2
It is carried out at a temperature of 70°C. If the temperature is lower than the above range, the melt viscosity will be too high, making melt molding difficult, and if the temperature is higher than the above range, the molecular weight of the ultra-high molecular weight polyolefin will decrease due to thermal degradation, resulting in an excellent high modulus. And it becomes difficult to obtain a molded article with high strength. The blending may be carried out by dry blending using a Henschel mixer, a V-type blender, or the like, or may be carried out using a single-screw extruder or a multi-screw extruder.

Dope consisting of ultra-high molecular weight polyolefin and diluent (
Melt molding of the spinning dope) is generally performed by melt extrusion molding. Specifically, filaments for drawing are obtained by melt extruding the dope through a spinneret.

At this time, the molten material extruded from the spinneret may be drafted, that is, drawn in the molten state. Extrusion speed V of the molten resin within the Daiken orifice. The ratio of the winding speed V of the cooled and solidified undrawn material can be defined as a draft ratio by the following formula.

Draft ratio -V/Vo (2) Such a draft ratio varies depending on the temperature of the mixture, the molecular weight of the ultra-high molecular weight polyolefin, etc., but can usually be 3 or more, preferably 6 or more.

Next, the unstretched molded ultra-high molecular weight polyrefine thus obtained is subjected to a stretching treatment. Stretching is carried out so as to effectively impart at least uniaxial molecular orientation to the unstretched molded article obtained from the ultra-high molecular weight polyolefin.

Stretching of unstretched molded bodies obtained from ultra-high molecular weight polyolefins is generally carried out at a temperature of 40 to 160°C, particularly 80 to 145°C. As the heat medium for heating and maintaining the unstretched molded body at the above temperature, air, steam, or a liquid medium can be used. However, as a heat medium, a liquid medium that is a solvent capable of eluting and removing the aforementioned diluent and whose boiling point is higher than the ridge point of the molded article composition, specifically, decalin, decane, kerosene, etc. is used. It is preferable to carry out the stretching operation in such a manner that the diluent described above can be removed, uneven stretching will not occur during stretching, and a high stretching ratio can be achieved.

The means for removing the diluent from the ultra-high molecular weight polyolefin is not limited to the above-mentioned method.
By removing the diluent in the molded product, there are methods in which the stretched product is treated with a solvent such as hot ethanol, chloroform, or benzene, and then stretched. , a stretched product with high elastic modulus and high strength can be obtained.・
The stretching operation can be performed in one stage or in multiple stages of two or more stages. The stretching ratio depends on the desired molecular orientation and the associated effect of increasing the melting temperature, but is generally between 5 and 5.
80 times, preferably 10 to 50 times.

In general, it is preferable to carry out the stretching operation in two or more stages, and in the -th stage, the stretching operation is carried out while extracting the diluent in the extrudate at a relatively low temperature of 80 to 120°C. From the second stage onward, it is preferable to stretch the molded body at a temperature of 120 to 160°C, and at a temperature higher than the first stage stretching temperature.

In the case of a uniaxial stretching operation, tension stretching may be performed between rollers having different circumferential speeds.

In the case of a biaxially stretched film, it is sufficient to perform tensile stretching in the longitudinal direction between rollers with different circumferential speeds, and also to perform tensile stretching in the transverse direction using a tenter, etc. Biaxially stretching using an inflation method is also possible. It is possible. Furthermore, in the case of a three-dimensional molded product such as a container, a biaxially stretched molded product can be obtained by a combination of axial stretching and expansion stretching in the circumferential direction.

The molecularly oriented molded product thus obtained can be heat-treated under restrictive conditions if desired.

This heat treatment is generally carried out at 140-180°C, preferably at 15°C.
At a temperature of 0 to 175°C for 1 to 20 minutes, preferably 3 to 1
It can be done for 0 minutes. The heat treatment further advances the crystallization of the oriented crystal parts, shifts the crystal melting temperature to a higher temperature side, improves the strength and elastic modulus, and further improves the creep resistance at high temperatures.

Effects of the Invention Since the ultra-high molecular weight polyolefin-based molecularly oriented molded article according to the present invention is composed of an ultra-high molecular weight polyolefin (A) and a specific amount of the stabilizer (B), it has long-term heat resistance. Excellent stability, maintains high tensile strength and high tensile modulus.

EXAMPLES Hereinafter, the present invention will be explained with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Ultra-high molecular weight polyethylene (intrinsic viscosity [η] -8,94d
A higher fatty acid metal salt was added to a mixture of 20 parts by weight of powder (measured in decalin solvent at 135°C) and 80 parts by weight of paraffin wax (manufactured by Nihon Seijun Co., Ltd., trade name Nilpax, melting point = 69°C) as a diluent. 0.3 parts by weight of calcium stearate (manufactured by Mitsui Organic Co., Ltd.) was added thereto, and melt-spun was carried out under the following conditions.

The mixture was extruded using a screw extruder (screw diameter 25 mm, L
/D-25, manufactured by Thermoplastics Co., Ltd.) at a set temperature of 190° C., and then the melt was melt-spun using a spinning die with an orifice diameter of 2 mm attached to an extruder. Next, the extruded melt was taken under the conditions of an air gap of 180 and a draft ratio of 35 times, and was cooled and solidified in air to obtain an undrawn fiber.

Furthermore, the undrawn fibers were drawn under the following conditions to obtain molecularly oriented fibers.

Two-stage stretching was performed using a Godetstrol made by Ohdai. At this time, the heating medium in the first drawing tank was n-decane at a temperature of 110°C, and the heating medium in the second drawing tank was triethylene glycol at a temperature of 145°C. The effective length of each tank was 50 cm. During the stretching, the rotational speed of the first godet roll was 0.5/min, and the rotational speed of the third godetroll was 12.5/min (stretching ratio: 25 times).

The rotational speed of the second godet roll was appropriately selected within a range that allowed stable operation. Almost all of the initially mixed paraffin wax was extracted into n-decane during stretching. Next, the obtained molecularly oriented fibers were washed with water and dried in a vacuum chamber for a day and a night.

The long-term heat resistance of the obtained molecularly oriented fibers is determined by the oxygen absorption rate,
Evaluation was made based on changes in intrinsic viscosity [η] and changes in tensile properties due to heat aging.

n1 constant of oxygen absorption rate> Molecularly oriented fibers were left in an oxygen atmosphere at 130°C using a CBP-4 UV type polymer material deterioration measurement device manufactured by Tsukiyama Scientific Instruments Manufacturing Co., Ltd., and the standard value per gram of molecularly oriented fibers was measured after 20 hours. The amount of oxygen absorbed in terms of state was measured. The smaller the amount of oxygen absorbed, the better the stability against oxidation.

Heat Aging Test> After the molecularly oriented fibers were left in a gear oven (Perfect Oven manufactured by Tabai Seisakusho) in an air atmosphere set at 100° C. for 500 hours, physical properties were measured. The smaller the decrease in the intrinsic viscosity [η] due to aging, the better the heat resistance stability.

(aP1 constant of tensile properties)
It was measured at room temperature (23°C) using a 0M type tensile tester. The test length between the clamps at this time was 100 m, and the tensile rate was 100+a+s/min (100% strain rate). The elastic modulus was calculated using the slope of the tangent at the initial elastic modulus. The fiber cross-sectional area required for calculation is density 0.960g/c
c was calculated from the weight.

The smaller the decrease in tensile strength, the better the heat resistance stability.

The results are shown in Table 1.

Example 2 In Example 1, magnesium stearate (NOF ■) was used instead of 0.3 parts by weight of calcium stearate.
Molecularly oriented fibers were obtained in the same manner as in Example 1, except that 0.3 parts by weight of 0.3 parts by weight of the following products were used, and the above-mentioned measurements were performed.

The results are shown in Table 1.

Example 3 The molecule was prepared in the same manner as in Example 1, except that 0.3 parts by weight of calcium 12-hydroxystearate (manufactured by NOF ■) was used instead of 0.3 parts by weight of calcium stearate. Oriented fibers were obtained and the n1 constant was performed.

The results are shown in Table 1.

Example 4 Molecularly oriented fibers were prepared in the same manner as in Example 1, except that 0.3 parts by weight of lithium stearate (manufactured by Sakai Kagaku ■) was used instead of 0.3 parts by weight of calcium stearate. was obtained and the above measurements were performed.

The results are shown in Table 1.

Example 5 Example 1 except that 0.3 parts by weight of lithium I2-hydro-bovine distearate (manufactured by Sakai Kagaku ■) was used instead of 0.3 parts by weight of calcium stearate.
Molecularly oriented fibers were obtained in the same manner as above, and the #J determination described above was performed.

The results are shown in Table 1.

Comparative Example 1 Molecularly oriented fibers were obtained in the same manner as in Example 1, except that the higher fatty acid metal salt was not used.
The above measurements were carried out.

The results are shown in Table 1.

Claims (1)

[Scope of Claims] 1) Contains (A) ultra-high molecular weight polyolefin, and (B) metal salt of higher fatty acid: 0.005 to 5 parts by weight per 100 parts by weight of (A) ultra-high molecular weight polyolefin. An ultra-high molecular weight polyolefin-based molecularly oriented molded product characterized by: