JPS58136639A - Polyolefin composition - Google Patents

Abstract

PURPOSE:To provide the titled compsn. which has excellent moldability and does not undergo discoloration, by blending a uniform mixture of a higher fatty acid and its alkali metal salt with a polyolefin. CONSTITUTION:A polyolefin compsn. is obtd. by blending a uniform mixture consisting of a higher fatty acid such as lauric acid or palmitic acid and its alkali metal salt such as sodium laurate or potassium palmitate with a polyolefin such as PE. Even when this compsn. is molded into a thin film by inflation, the film little suffers bursting at its expanded part and a stable continuous operation is possible. Even when high-speed melt spinning is conducted to produce a monofilament, thread breakage does not occur. With regard to the possibility of discoloration caused by the use of potassium salt of a higher fatty acid, a sufficient discoloration preventing effect can be obtd. by mixing a powdered higher fatty acid.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to polyolefin compositions. More specifically, the present invention relates to a polyolefin composition with excellent moldability and no coloration.

It is a well-known technique to blend higher fatty acid metal salts into polyolefins produced using Chiigutai catalysts, such as polyethylene and polypropylene, for the purpose of imparting rust prevention properties and increasing the discharge amount during melt extrusion. Calcium stearate is commonly used as a higher fatty acid salt. By the way, if an alkali metal salt, typified by calcium stearate, is used instead of an alkaline earth metal salt of a higher fatty acid, the discharge volume during melt extrusion becomes even larger; When used in combination with a 7-enol stabilizer, there is a drawback that the hue deteriorates.

Furthermore, polyethylene blended with higher fatty acid metal salts, whether alkali metal salts or alkaline earth metal salts, can be formed into films, especially thinner films, by melt extrusion, inflation molding, etc., or blow molding. When bottles are molded by this method, the appearance of the molded film is greatly deteriorated by the agglomerates of higher fatty acid metal salts formed therein.
When a thin film is made by inflation molding,
Due to the presence of such agglomerates, the conical part, which should be stretched by air pressure and form a stable cylinder, suddenly splits, making it possible to continuously and stably produce a thin film. There is a serious problem of not being able to do so.

As a result of extensive research into a polyolefin composition that can maintain a good discharge rate during melt extrusion without having to overcome these drawbacks, the present inventors have found that a homogeneous mixture of higher fatty acids and their alkali metal salts is blended into polyolefin. It is important to note that everything can achieve the desired goal.

The polyolefin to be modified is polyethylene, polypropylene, poly(4-methyl-1-pentene), etc., preferably polyethylene61), KFi for producing ultrathin films by inflation molding method,
Its melt index (190℃) is approximately QOa ~
CL(15, density fil about α95~49611A- is desirable.

The higher fatty acids used in the form of alkali metal salts and free acids, respectively, have 10 or more carbon atoms, preferably 1
Examples of higher fatty acids 4 to 24 include capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and lignoceric acid. Examples of alkali gold maple salts include sodium salts, potassium salts, lithium salts, etc. of these higher fatty acids, such as steari/11111 lithium, sodium palmitate, sodium stearate, sodium laurate,
Valmitine potassium stirrup, potassium stearate, potassium Araki/II, etc. are used.

When only these higher fatty acid alkali metal salts are blended into polyolefin and the granules are molded, aggregates of higher fatty acid alkali metal salts are likely to be formed in the molded product, and the formation of aggregates depends on the blending ratio. However, if the higher fatty acid is mixed at a ratio of about 0.1 to 400%, preferably about 1 to 100%, more preferably 5 to 30% by weight, the higher fatty acid alkali metal salt is mixed. At this mixing ratio, it is not possible to suppress the formation of aggregates, and on the other hand, at higher mixing ratios, the rust prevention properties of the alkali metal salts are reduced, leading to a deterioration of the working environment such as bad odors during good molding). On the other hand, the weight is about αos
-g%, preferably about αOδ to 1%, and when granulated, it exhibits good formability and anti-corrosion properties, and is free of higher fatty acid alkali metal salts in the articles molded from it. Aggregate formation is also effectively suppressed.

The effect of suppressing aggregate formation greatly depends on the mixing state of the higher fatty acid and its alkali metal salt, and the more uniform the mixing state, the greater the suppressing effect. These methods can be mixed by tri-blending using a tumbler mixer, Henschel mixer, etc., by melt-mixing the tri-blend while stirring, cooling after cooling, and pulverizing the tri-blend. This is done by dissolving and mixing in a solvent such as alcohol, removing the solvent, and pulverizing. In this order, a uniformly mixed state is formed.

Besides these methods, 41#! cA preferred method is to use a smaller equivalent amount of alkali metal hydroxide to the higher fat IIIK or F! Examples include a method of adding an oxide, neutralizing it in a molten state, and pulverizing it, or a method of neutralizing it in a solvent such as alcohol and removing the solvent.

A polyolefin composition blended with a homogeneous mixture of higher fatty acids and their alkali metal salts in this manner improves moldability and non-coloring properties while maintaining a good discharge rate during melt extrusion. In terms of moldability, the formation of aggregates of higher fatty acid alkali metal salts that spoil the appearance of molded products such as films and bottles is effectively suppressed.
Even when a thin film is formed using the inflation method, there is almost no rupture of the expanded part, and therefore stable continuous operation is possible69. Similarly, when high-speed melt spinning of monofilament etc. is performed, In order to cope with this problem, a large amount of higher fatty acid metal salt is blended to form aggregates and cause thread breakage, and the draw ratio tTotb.
To effectively solve problems such as the failure to improve the strength of a mourning thread that cannot be improved. Furthermore, regarding the coloring property seen in the case of higher fatty acid potassium salts, a sufficient coloring prevention effect can be seen even if the powder is mixed with higher fatty acid III.

Next, the present invention will be explained with reference to examples.

Example 1-4. Comparative Examples 1 to 6 Polyethylene powder (melt index α0415) manufactured by K11ll using a highly active TIG 2-based catalyst without going through a catalyst removal factory, O as a 49ization inhibitor:
2-Methylheptyl ester of S-<4-hydroxy-3,5-di-tert-butylphenyl)propionic acid 0015
Weight% (relative to polyethylene, same below), phosphorus stabilizer (
Adeka Argus product, mark fs29K) 01% by weight
Further, a mixture of stearic acid and its alkali metal salt shown in the table below was heated to 80 to 100°C, and then mixed under a nitrogen atmosphere using a Henschel electric mixer.
The mixture was granulated into pellets using an extruder at a resin temperature of 60°C.

This granulated pellet is fed to an inflation molding machine,
After melting in a cylinder, it was extruded into a tube shape through a ring die. After closing one end of this tube by passing two vinyl rolls through it,
Expand it to a predetermined size by blowing in air, adjust the deposition speed, and make it to a thickness of 6μ (however, only Comparative Example 1 is lOμ).
9. Roll up the tubular film, and perform this operation continuously for two days.

〔Molding condition〕

8 machines: Modern Co., Ltd. 1IK50 inflator/molding machine (cylinder inner diameter 5Qm, screw metal ring VD-26, die 3-line spiral method) 6 diameter XL 2wm) Blow-up ratio: 5 Temperature (resin temperature lj): 21B℃ [Evaluation method] Measured with a pressure gauge attached to the joint between resin pressure crab die and cylinder (uses as a guideline for moldability) Extrusion amount ″: unit time comb film winding weight Rust prevention
: We disassembled the Inflake 8-frame molding machine, inspected each part of the cylinder, die, and screw, and observed the presence or absence of reddish-brown rust. Molding characteristics stability: Constantly monitored the expanding part during film molding,
It is judged to be good when the expansion part is formed stably without abnormality for 2 days. Film color: It is judged to be good if it is translucent white when visually inspected under sunlight. 9. Appearance of the film: During molding The film was monitored and determined just before the winder (Put is a foreign substance thought to be a stearate metal salt aggregate). Preparation was carried out as follows.

A mixture of alkali metal salts of stearin and stearic acid B: Sodium hydroxide 1+ is obtained by melting potassium hydroxide with an excess equivalent ratio of stearic acid, neutralizing a portion of the stearic acid, and pulverizing the mixture. Sodium nistearate and stearic acid were mixed with polyethylene powder in a Henschel mixer and granulated without pre-mixing.

Claims (1)

[Claims] Claim 1, wherein the polyolefin polyolefin prepared by blending a homogeneous mixture of -grade fatty acids and their alkali metal salts is polyethylene.
The polyolefin composition described in IJ. K. The polyolefin composition according to claim 11I or claim 2 used. The polyole and fin set "paraboloid" according to claim 3, which is used for molding the present inflatable N7.