JPS59176339A - Method for molding polyolefin - Google Patents

Abstract

PURPOSE:To produce a molding having good appearance and surface profile with a high extrusion rate while extruding at a high temp. region (230 deg.C or above), by using a polyolefin compsn. contg. a specified fluorine compd. CONSTITUTION:0.001-2pts.wt. potassium fluoroalkylsulfonate (e.g. potassium perfluorobutylsulfonate) is blended with 100pts.wt. polyolefin (pref. polyethylene having a weight-average MW of 70,000 or above and the ratio of weight-average MW to number-average MW of 7 or below). The resulting resin compsn. is extruded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for extruding polyolefins. More specifically, the present invention relates to a molding method that improves the extrusion moldability of polyolefin in a high temperature range.

When extrusion molding a polyolefin, if the fluidity during melt-kneading is poor, that is, if the melt viscosity is high, the extrusion rate will be low or the polyolefin will deteriorate due to the generation of frictional heat, making it impossible to obtain a suitable molded product. For example, when molding monofilament using a die with a very small extrusion nozzle compared to other extrusion molds, in order to prevent the filament extruded from the nozzle from causing melt fracture, the resin is It is necessary to sufficiently knead the materials, raise the extrusion temperature, and lower the melt viscosity before extrusion. However, many monofilament brands have narrower molecular weight distributions or higher molecular weights than regular brands in order to enhance linear strength and knot strength. Such a narrow molecular weight distribution or high molecular weight improves the properties mentioned above, but on the other hand, it causes an increase in melt viscosity, resulting in a decrease in molding processability, a decrease in extrusion rate, and a change in the surface of the molded product. This will deteriorate the appearance such as smoothness. It is possible to improve moldability, that is, increase the extrusion rate, by increasing the extruder's screw rotation speed or raising the molding temperature, but the former does not change the melt viscosity of the resin itself. As a result, the resin pressure increases, the motor load on the extruder increases, and more frictional heat is generated, causing resin deterioration.Furthermore, as a result of insufficient kneading, the appearance is poor and the stretching breakage occurs. A filament that is easy to raise is obtained. In the case of the latter, if the temperature is too high, the resin will deteriorate and a good molded product will not be obtained. The above-mentioned problems are not limited to monofilament molding, but apply to all narrow molecular weight distribution or high molecular weight polyolefins.

In order to solve the above problems, a lubricant is added to reduce the apparent melt viscosity of the resin and improve melt fluidity.
It has been widely practiced to improve moldability. However, among the various known lubricants, there are only a limited number of them that have good effects on polyolefins, and many of them require a large amount to be added in order to produce the effect as a lubricant, or they decompose in high temperature ranges. or volatilize, making it impossible to exert sufficient lubricant effect. For this reason, there is a desire for a lubricant compound for polyolefins that can sufficiently exhibit its lubricant effect even in high-temperature ranges even when incorporated in a small amount.

The present inventors have already discovered that certain fluorine compounds are effective as lubricants for polyolefins, and have filed an application for the same. This was achieved by discovering that it provides excellent melt fluidity in the above high temperature range.

That is, the present invention provides a method for molding polyolefin, which comprises blending 0.001 to 2 parts by weight of a potassium fluoroalkyl sulfonate salt with 100 parts by weight of polyolefin, and melt-extruding the mixture at a temperature of 230°C or higher. It is.

The fluoroalkylsulfonic acid potassium salt used in the present invention is represented by the general formula RfS O3K, and R
f is a chain or cyclic alkyl group in which at least one hydrogen atom is substituted with a fluorine atom (branches may exist), and the number of carbon atoms is 2 or more, particularly 4 to 1.
A range of 8 is preferred. If the number of carbon atoms is less than 4, it will easily volatilize during molding.

Among these, perfluoroalkylsulfonic acid potassium salts in which all hydrogen atoms are replaced with fluorine atoms are preferred because they suitably exhibit the effects of the present invention. Specifically, general formula CnF2n+1S03K (here preferably n
is an integer from 2 to 1 day), for example, potassium perfluorobutyl sulfonate (
C4F9SO3K), potassium perfluoropentyl sulfonate (05F11SO3K), potassium perfluorohexyl sulfonate (06F13SO3K), potassium perfluorohebutyl sulfonate (07F15
S03K), potassium perfluorooctyl sulfonate (08F17S03K), potassium perfluorononyl sulfonate (09F 19 S O3K ), potassium perfluorodecyl sulfonate (C1oH2o
S03K), potassium perfluoroundecylsulfonate (C11F23803K), potassium perfluorododecylsulfonate (012F25S03K), potassium perfluorotridecylsulfonate ((! 13 F
27 S O3K ) % Potassium perfluorotetradecyl sulfonate (014F29S06K), Potassium perfluorooctadecylsulfonate (c 1s
F37 S 03 x ) etc.

Fluoroalkylsulfonate potassium salt ＼Compared with other fluoroalkylsulfonates such as fluoroalkylsulfonate sodium salt, fluoroalkylsulfonate calcium salt, fluoroalkylsulfonate lithium salt, fluoroalkylsulfonate ammonium salt, etc. When mixed with polyolefin, 23
When the temperature reaches a high temperature range of 0° C. or higher, the melting lubricity effect rapidly increases, which is a temperature-dependent effect. Therefore, a sufficient lubricating effect can be imparted to the polyolefin with a small amount of blending, and it is possible to improve the extrusion rate and the surface condition of the molded product without impairing the properties of the polyolefin. This also applies to other fluoroalkyl group-containing compounds,
For example, this is a unique effect that is not seen even with fluoroalkylcarboxylic acids and their salts.

Another effect is that when polyolefin containing potassium fluoroalkyl sulfonate is extruded,
At the same screw rotation speed, the extrusion amount increases compared to polyolefin without additives.

This is unexpected since when a lubricant is added, the amount of extrusion decreases compared to a product without additives at the same screw rotation speed (resin pressure also decreases, and the amount of extrusion increases at the same resin pressure). As a result, according to the method of the present invention, the extrusion amount can be increased at low resin pressure without increasing the motor load of the extruder.

The polyolefin used in the present invention is a homopolymer of α-olefins such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, and 16-methyl-1-butene. or a copolymer consisting of two or more comonomers, or a copolymer of α-olefin and other copolymerizable monomers, such as styrene, acrylonitrile, vinyl chloride, vinyl acetate, acrylic ester, methacrylic ester, etc. Alternatively, any polyolefin may be used, such as the above-mentioned polyolefins or blends with other thermoplastic resins, block copolymers, and graft copolymers. Among these, polyolefins with narrow molecular weight distribution and high molecular weight, which are molded in a high temperature range of 230° C. or higher, are particularly suitable. Such narrow molecular weight distribution and high molecular weight polyolefins include, for example, weight average molecular weight (Mw
) is 70,000 or more, and the ratio of weight average molecular weight to number average molecular weight (
Mw/Mn) is 7 or less polyethylene, 1Avi is 5
Polypropylene with a MW of 1,000,000 or more and a Mw/Mll of 10 or less, a MW of 1,000,000 or more and a Kl w / Mn of 20
Examples include the following polybutene-1. In addition, MW here.

M'it/Mn can be easily measured by gel permeation chromatography at 165°C using 0-dichlorobenzene as a solvent and standard substances with known molecular weights (monodisperse polystyrene and polyethylene).

In the molding method of the present invention, 0.001 to 2 parts by weight, particularly 0.5 to 1.5 parts by weight of CLO05 to 1.5 parts by weight of the potassium fluoroalkyl sulfonate salt is blended when polyolefin is melt-extruded in a high temperature range of 260°C or higher. By doing so, the apparent melt viscosity of the polyolefin is lowered, resulting in an increase in extrusion rate and an improvement in the surface condition of the molded product. If the blending amount is less than o or ooi parts by weight, the lubricity effect cannot be imparted, and if the blending amount is more than 2 parts by weight, the lubricity effect becomes too large, increasing the slip property at some parts of the extruder screw, and improving the molding processability. In addition to causing a decrease in the temperature, bleed-out also occurs.

Various known methods can be used to blend the fluoroalkylsulfonic acid potassium salt into the polyolefin. For example, mixing both components in a ribbon blender, tumbler blender, Henschel mixer, etc.
Alternatively, after mixing, there is a method of melt-mixing using an extruder, one or two rolls of a Banbury mixer, or a method of dissolving the mixture in a hydrocarbon or aromatic solvent and mixing it into a polymer solution.

In order to extrude the mixture of polyolefin and fluoroalkylsulfonate potassium salt obtained in this way at a molding temperature of 230°C or higher, various known extruders such as a single screw extruder, a vent type extruder, and a double extruder can be used. Main screw extruder, three-screw extruder, conical two-screw extruder, co-negoo, plateificator, mixtruder, twin-screw conical screw extruder, planetary screw extruder, gear extruder, screw We perform heavy bibing molding, inflation molding, sheeting molding, lamination molding, monofilament molding, wire coating molding, etc. using a non-resistance extruder.

By performing high-temperature extrusion molding of polyolefin using the method of the present invention, it is possible to stably increase the amount of extrusion, and also improve the surface condition and appearance of the molded product, which can greatly contribute to mass production and cost reduction. It is.

Examples of the polyolefin molding method according to the method of the present invention will be described below, but the method is not limited to these examples unless the gist of the present invention is exceeded.

Examples 1 to 2 and Comparative Examples 1 to 3 Density 0.954 g/c1n3% 190°C"'C Measurement Sit, =, Ilt Index 0.9 g/10
0.6 parts by weight each of dilauryl thiodipropionate and 3,5-di-t-butyl-4-hydroxytoluene as stabilizers were added to 100 parts by weight of min polyethylene (HIZEX 5000Si Mitsui Petrochemical Industries).
0.1 part by weight was blended, and the fluoroalkyl sulfonic acid compound shown in Table 1 was further blended to give a screw diameter of 2Q mm.
It was granulated at 200°C using an extruder with φ and L/D = 26. Granulated polyethylene with a screw diameter of 20 mmφ,
L/D-20 extruder with nozzle diameter 1mmφ, L/D =
15 nozzles were installed, and extrusion molding was performed using a full-flight type screw while varying the resin temperature from 170'C to 300°C, and the extrusion pressure (250 kg/
The extrusion amount in cm2) was measured. The results are shown in Table 1 and Figure 1.

Example 6 and Comparative Example 4 Melt index measured at 230°C 1.2 g/
Irganox 1010 and 3,5-zyl-t-butyl-4- as stabilizers were added to 100 parts by weight of polypropylene (Mitsui Petrochemical Polypropylene, T-300) of 10 min.
Test Example 4 and Comparative Example 5 were prepared in the same manner as Example 1 by blending 0.1 part by weight of hydroxytoluene and further blending the fluoroalkyl sulfonic acid compounds shown in Table 2.
~7 The polyethylene of Example 1 was blended with the fluoroalkylsulfonic acid compounds shown in Table 6 and granulated. The granulated polyethylene was extruded at 260°C using the same extruder as in Example 1 while changing the screw rotation speed, and the extrusion amount was measured. Conclusion

[Brief explanation of drawings]

Claims (2)

[Claims] (1) A method for molding a polyolefin, which comprises blending 100 parts by weight of a polyolefin with C1, CI 01 to 2 parts by weight of a potassium fluoroalkyl sulfonate salt, and melt-extruding the mixture at a temperature of 230°C or higher. (2) The method for molding a polyolefin according to claim 1, wherein the fluoroalkyl sulfonate potassium salt is a perfluoroalkyl sulfonate potassium salt.