JPS59129241A - Novel polyethylene composition - Google Patents

Abstract

PURPOSE:To provide a polyethylene compsn. having excellent long-term continuous processability and pigment-colorability, by incorporating specified quantities of two higher fatty acid metal salts. CONSTITUTION:Calcium salt of a higher fatty acid (A) (10C or higher), such as calcium stearate, and zinc salt of a higher fatty acid (B), such as zinc stearate, are used togeher. 500-4,000ppm of component A and 200-3,000ppm of component B are added to polyethylene having a melt index (ASTM-D1238, at 190 deg.C, load 2.16kg) of 10 or above in a combined quantity of components A and B of 1,000-6,000ppm. The mixture is kneaded with heating at 130-330 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyethylene composition having excellent long-term continuous processability and excellent pigment colorability.

Polyethylene is produced by extrusion molding into ξiso, notebook, etc.
It is formed into a film by methods such as ml tor, hollow molded product, T-die, and inflation method by blow molding, and monofilament, stretched tape, etc. by stretch molding. These molding methods reduce the raw material polyethylene to the melting temperature (
The essential step is to melt the resin at a temperature above the melting point (melting point) and continuously extrude the molten resin through a narrow slit, gouer, nozzle, etc. In such a continuous extrusion processing method, as the continuous extrusion processing time becomes longer, sticky deposits accumulate inside the slit, gou, nozzle, etc. and around the exit. The amount of such deposits increases as the processing time increases, and eventually the product no longer causes various problems such as scratches on the surface of the molded product, abnormal dimensions of the molded product, and holes and cuts in the molded product. . When this happens, it is no longer possible to continue manufacturing molded products, so the machine must be temporarily stopped and the slits, gouers, nozzles, etc., must be cleaned. Temporarily stopping production for such reasons is undesirable because it causes a decrease in productivity. That is, the less frequently the machine is stopped for cleaning, in other words, the longer the time for continuous extrusion processing, the better the productivity will be. The occurrence and growth of such deposits is particularly remarkable when colored molded articles are manufactured by adding pigments. The greater the amount of pigment added, the more the generation and growth of deposits will be promoted.

Therefore, by adding metal salts of fatty acids to polyethylene, it is possible to improve extrudability, lubricity with metals, etc. Handbook).

- Polyethylene compositions to which calcium or zinc salts of fatty acids have been added are still commercially available. However, even with such polyethylene compositions, fully satisfactory results have not been obtained.

As a result of repeated research on improving the continuous extrusion process for polyethylene, the present inventors discovered that by adding two types of metal salts of higher fatty acids, calcium salts and zinc salts, to polyethylene in specific amounts and ratios. It was discovered that the continuous extrusion processability was improved by a synergistic effect, and the present invention was achieved.

That is, the present invention provides calcium salts of higher fatty acids (A)
Polyethylene with a melt index of 10 or less and containing zinc salts of higher fatty acids (I3), and the amount of calcium salts of higher fatty acids (A) is 500% relative to polyethylene.
ppm to 4000 ppm, higher fatty acid zinc salt (B) to polyethylene 200 ppm to 30
00 ppm or less, the amount of i + (B) of (A, ) is 100
This is a polyethylene composition characterized in that the content is 0 ppm or more and 6000 ppm or less.

The effects of the composition of the present invention are specifically listed below.

(1) During extrusion molding, there is less deposits on the goo, slit, nozzle, etc., and the continuous extrusion time is extended several to several tens of times compared to conventional polyethylene.

(2) Good coloring properties when pigments are added, allowing for deep coloring with a small amount of pigments.

(3) Mechanical properties such as strength, elongation, impact resistance, heat resistance,
Thermal properties such as dimensional stability are superior to those of conventional polyethylene.

(4) Excellent moldability.

(5) The composition is extremely easy to manufacture.

(6) The composition has a wide range of applications. In particular, the seat,
It is particularly effective in extrusion molding of pipes, blow molding, film molding, and stretching molding of monofilaments, stretched tapes, etc. It is also possible to perform injection molding, thermoforming, rotational molding, etc.

Hereinafter, the content of the present invention will be explained in detail.

In the composition of the present invention, it refers to a composition mainly composed of polyethylene, a homopolymer of ethylene, and a copolymer of ethylene and a small amount of other olefin. Examples include high-density polyethylene, medium-density polyethylene, low-density polyethylene, and mixtures thereof. Furthermore, the polyethylene used in the present invention has a melt index of ASTM D1238, a temperature of 190°C, and a load of 2.
．． At 16KS', it is less than 1O. When the melt index (hereinafter referred to as M and I) exceeds 10, the composition of the present invention loses its characteristics because the effect of inhibiting the generation and growth of the deposit is low.

The calcium and zinc salts of higher fatty acids used in the present invention refer to higher fatty acids having 10 or more carbon atoms, such as stearic acid, lauric acid, myristic acid, nomilmitic acid, lignoceric acid, cerotic acid, and montanic acid. , calcium salts (A) and zinc salts (B) of higher fatty acids such as ricinoleic acid, laurolenic acid, behenic acid, oleic acid, or linoleic acid. The amount and proportion of the higher fatty acid salt used in the present invention may be within the following range. Amount of (A): 50 for polyethylene
0 ppm or more and 4-000 ppm or less, the amount of (B);
200 ppm or more 3000 p for polyethylene
pm or less, amount of (A) + amount of (B): 1000 pp
m or more and 6000 ppm or less. Amount of (A), (B
) and amount of (A,) -1 - amount of (B), if any one of them is out of the above range, the occurrence and growth of the deposit will be the same as in conventionally known polyethylene compositions. Yes, there are no features of the present invention.

More preferable amounts and proportions are as follows; in this case, the effect of suppressing the occurrence and growth of deposits is outstanding, and in addition, the pigment color development of molded products such as monofilaments, stretched tapes, thin films, etc. due to stretching orientation is extremely high. In good condition. That is, the amount of (A) is 800 ppm or more and 3500 ppm or less based on polyethylene. Amount of (B): 400 ppm or more and 2500 ppm or less based on polyethylene. (A)
amount + amount of (B); 1500 ppm or more 45001)
I) m or less. Note that the term "stretch-oriented molded product" as used herein means that the polyethylene composition is once melted at a temperature higher than the melting temperature and lower than the thermal decomposition temperature, then cooled and solidified, and then the solidified product is further melted at a temperature lower than the melting temperature. - Molded products stretched in the axial direction or biaxial direction at a stretching ratio of 2 times or more, such as the above-mentioned monofilaments, stretched tapes, and uniaxially and biaxially stretched films.

The method for producing the polyethylene composition of the present invention includes a method of heating and kneading polyethylene, (A) and CB) at the same time, or a method of heating and kneading polyethylene, (A) and polyethylene and (B) in advance. , a method of adding the remaining ingredients and kneading with heat, and a method of heat-kneading (A) or (B), Master S Nochi containing Bota (A) and (B) with polyethylene, etc. As the heating and kneading device, commonly used mixers such as various extruders, non-tanley mixers, Ni-goo mixers, mixing rolls, etc. can be used. Alternatively, heating and kneading can be carried out simultaneously with molding in an extruder or the like for molding. In fact, it is recommended to premix before heating and kneading, but as a premixing device, commonly used mixers such as drum cylinder type blender, ribbon blender, Henschel mixer, etc. Other mixers can be used. The heating cross-wire temperature is in the range from the melting and softening temperature of polyethylene to the thermal decomposition temperature, and is usually carried out at 130°C to 330°C.

In addition to the above essential components, the IJ ethylene composition of the present invention contains heat stabilizers, ultraviolet absorbers, plasticizers, pigments, antistatic agents, thickeners, foaming agents, flame retardants, rubber component polymers, and other polyolefins. , and may contain small amounts of other additives.

The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited only to the scope of the examples.

Example I M, I is 1.5, density is 0.948, zoropyrene is 0.
4 mot% copolymerized high density, t91) ethylene powder, butylated hydroxytoluene 11l 100pp calcium stearate 2500 as a heat stabilizer
ppm and 1200 ppm of zinc stearate were added, mixed well in a drum cylinder, and then heated in an extruder with a screw diameter of 651 run at a temperature of 250 °C at 40 °C.
Kneading extrusion and pelletizing were performed at an extrusion speed of Ky/1-ir to produce pellets f of a high density polyethylene composition containing butylated hydroxytoluene, calcium stearate, and zinc stearate.

Monofilament I was made from the pellet of this high-density polyethylene composition using the following machine and under the following conditions.

(1) Machine; a. Extruder; screw diameter 401 mm, die; nozzle diameter 0.8 wn, 40 holes C
5 Cooling tank, water cooling type, effective length 501 near 71d, stretching tank, hot water type, effective length 1.5m e, stretching machine: 1 stage stretching system f8 winder with 1 stage of low speed roll and 1 stage of high speed roll, Zevin winding method with torque motor (2) Monofilament manufacturing conditions a, extrusion temperature, 270℃ b, die-cooling water surface distance: 30 degrees C0 cooling water temperature: 30℃ d, hot water temperature in drawing tank; 98℃ e, Stretching ratio: 12 times f1 Winding speed i 150771/min, monofilament Dale: 3007' Neil (3) Pigment Master Patch manufactured by Tokyo Ink 540323 Blue This master patch was added to 1.5 parts by weight of the above high density polyethylene. Parts by weight were mixed and charged into the above extruder for spinning. In addition, the pigment master patch was added to
This is to promote the generation and growth of deposits on the exit surface of the nozzle.

(4) Determination of continuous monofilament production time Monofilaments were produced continuously using the method and conditions described above. When the winding dubbin is full, is there an empty S? Switch to bin,
Continuous production was carried out. If the yarn was cut in the drawing tank or the like during the process, it was returned to its original state and continuous production was performed.

Production continued continuously as long as the thread cutting frequency was no more than two threads per hour. The time when the thread cutting frequency exceeds 2 threads per hour is determined as the time when continuous production is impossible,
The time up to this point was determined to be the continuous manufacturing time. We simultaneously observed the formation and growth of deposits on the surface of the trench. As a quantitative expression of the deposits, the number of deposits having one length or more was counted.

(5) Evaluation of colorability of monofilament using the above method,
Quantitative expression of pigment colorability of monofilament produced under the following conditions is...A light source is irradiated onto the monofilament wound under certain conditions using a lid method color machine (7, the value of 1 measured thereby). The smaller the L value, the darker the monofilament appears to the naked eye. Conversely, the larger the I value, the lighter the monofilament appears to the naked eye.

(6) Test results Continuous production of monofilament was possible even after 4 days (96 hours) had passed, and there was no breakage of the yarn during spinning. Moreover, the number of deposits after 4 days was 2. The L value, which indicates the colorability of the pigment, was 24. These results are summarized in Table 1.

Examples 2 to 5 and Comparative Examples 1 to 7 Polyethylene compositions were prepared in the same manner as in Example 1 except that the high density polyethylene used in Example 1 was used and the additive compositions were as shown in Table 1. We investigated its construction and performance. The results are shown in Table 1.

As shown in Table 1, in Examples 1 to 5 according to the present invention, the occurrence of deposits under the nozzle was small, the continuous production time was long,
Low L value (good colorability with pigments). -Comparative Examples 1 to 7, which are not based on the strength wood invention, may have low L values, but all have a short continuous production time and often generate deposits under the nozzle.

Example 6 Tetrakis[methylene-3-(3',5'-di-t-butyl-4 '-Hydroxyphenyl)propiomate]methane 11000p
P, 2500 ppm of calcium stearate, and 500 ppm of zinc stearate were added, mixed well in a drum blender, and then extruded in a 65-diameter extruder with a gormage at a temperature of 250 °C and an extrusion speed of 30 Ky/Hr. Kneading and extrusion and berequiz were performed to produce pellets of the high density polyethylene composition containing the above heat stabilizer, calcium stearate and zinc stearate. A blown film was made from this pellet using the following machine and conditions.

(1) Machine a, extruder; screw diameter 50 mm 1), die; spiral tie, lip gap I W
rm.

Diameter: 50mm (2) Conditions a, extrusion temperature: 200°C b, blow ratio: 1゛3 C2 film thickness: 16 microns d, take-up speed: B □ m/m1n (3) Pigment Master ζ Tsuchi, manufactured by Dainippon Ink UF 7185 White This Master 7'! 5 parts by weight of Sochi was mixed with 100 parts by weight of the above-mentioned high-density polyethylene, and the mixture was charged into the above-mentioned machine to form a film. The reason why Pigment Master and S Sochi were added was to promote the generation and growth of deposits on the exit surface of the Guilip.

(4) The above method for determining the continuous production time of the film;
Films were produced continuously under the following conditions.

If the film was cut during production, it was returned to its original state and continuous production was performed. Cutting frequency of film is 1
Production continued continuously as long as it was no more than twice an hour. The time when the frequency of cutting the film decreased by one hour and exceeded twice was determined to be the time when continuous production was impossible, and the time up to that point was determined to be the time during which continuous production was possible.

In addition, the occurrence and growth of deposits on the Guylip surface were simultaneously observed with the naked eye. As a quantitative expression of the sediment, we measured the height of the sediment around Gwilyp.

(5) Test results Continuous production of the film was possible even after 3 days (72 hours) had passed, and there was no cutting of the film.

The height of the deposit after 3 days was 1 to 2 tran. These results are summarized in Table 2.

Examples γ to 9 and Comparative Examples 8 to 11 Polyethylene compositions were prepared in the same manner as in Example 6 except that the high density polyethylene used in Example 2 was used and the additive compositions were as shown in Table 2. We investigated its construction and performance. The results are shown in Table 2. As shown in Table 2, in Examples 6 to 9 according to the present invention, the occurrence and growth of deposits around the grip was small, and the continuous production OJ waiting time was long. - In Comparative Examples 8 to 11, which are not based on the present invention, the continuous production time is short, and deposits around the grips often occur and grow.

(Hereinafter referred to as Ij, -color) As explained above, the polyethylene composition according to the present invention has the following properties compared to conventionally known polyethylene compositions:
In the melt extrusion process, the generation and growth of deposits inside slits, dies, nozzles, etc. and near the exit are small, the continuous production time is long, the productivity is significantly the same as above, and the pigment colorability of the stretched molded product is excellent. Since the amount of pigment added can be reduced, costs can be reduced, making it extremely useful in practice.

Patent applicant Asahi Kasei Industries, Ltd.

Claims (2)

[Claims] (1) Melt index is 10 or less, higher fatty acid calcilyl, salt (A) and higher fatty acid zinc salt (B
) in the following amounts and proportions: 500 ppm relative to I'lyethylene
4000 ppm or more (I amount, 200 ppm or more and 3000 ppm or less (A) + (rl) amount; 1000 ppm or more6)
000 ppm or less (2) The polyethylene composition according to claim 1, wherein the amounts of the calcium salt of higher fatty acid (A) and the zinc salt of higher fatty acid (13) and their ratios are as shown below, respectively ( A) No, 11 + A? Boo for polyethylene
Amount of ppm or more and 3500ppH+ or less (B); 400ppm or more2 for polyethylene
500 ppm or less (A,) amount + (B) amount; 1500 pprn or more and 45009 pm or less