JPH07126447A - Polyethylene resin composition - Google Patents

Abstract

PURPOSE:To obtain a polyethylene resin composition improved in transparency, hardly causing clogging and enabling long-term continuous operation when the resin composition is molded or stretched, excellent in surface smoothness of extrusion moldings, having more uniform whiteness, having vivid color when colored and hardly causing the change in color tone. CONSTITUTION:This polyethylene resin composition contains 100 pts.wt. of polyethylene having 0.01-100g/10min melt index and 0.940-0.970 density and 0.01-1 pt.wt. of a mixture of a magnesium basic 12-hydroxystearate and zinc 12-hydroxystearate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene resin composition mainly composed of high-density polyethylene and having improved transparency.

[0002]

2. Description of the Related Art High density polyethylene is obtained by polymerizing ethylene and the like using a Ziegler type catalyst. Suitable catalysts for the polymerization include halogen compounds of transition metals such as titanium, and various methods for preparing the transition metal halogen compounds are known.

The resin composition containing high-density polyethylene as a main component is used for extrusion molded products such as films and sheets, and stretch molded products such as flat yarns, tapes and monofilaments. The stretch-molded product is obtained by melting and kneading the resin composition, then extrusion-molding and further stretching.
These extrusion-molded products and stretch-molded products are widely used for various bags, cloth sheets, ropes, nets, binding materials, non-woven fabrics, packaging materials such as films, industrial materials and the like.

[0004]

In some cases, the transparency of a resin composition containing high-density polyethylene as a main component and containing an additive, particularly a stretch-molded product, is insufficient. If the transparency was not sufficient, the whiteness of some areas was different from the whiteness of other areas, and some areas may appear more transparent than others. Further, if the transparency is not sufficient, it becomes difficult for the color to become vivid when colored. Further, depending on the additive, the color of the resin composition may change from white to yellow during storage of the resin composition (for example, pellets), and such prevention of yellowing has been demanded.

Japanese Patent Laid-Open No. 4-119170 discloses a high-density polyethylene resin composition containing calcium stearate and zinc stearate in order to improve the transparency of the monofilament. However, although transparency is improved with this resin composition, the filter may be clogged when melt-kneaded and extruded into a filament shape, and the filter may be replaced continuously for many days. It was difficult to operate. Further, according to the research conducted by the present inventors, the transparency was improved and the clogging of the filter was also eliminated by adding the fatty acid amide. However, the color of the resin composition changed from white to white by long-term storage. There was a problem of turning yellow.

[0006]

Therefore, the present inventor further improved the transparency of the high-density polyethylene resin composition,
At the same time, in order to improve the moldability, it was found that it was effective to blend a mixture of basic 12-hydroxystearate and zinc 12-hydroxystearate, and the present invention was completed.

According to the present invention, 100 parts by weight of polyethylene having a melt index of 0.01 to 100 g / 10 min. And a density of 0.940 to 0.970 g / cm ³ and basic 12-hydroxy are used. Provided is a polyethylene resin composition comprising 0.01 to 1 part by weight of a mixture of magnesium stearate and zinc 12-hydroxystearate. Further, in the present invention, the mixture is 70 to 90% by weight of the basic magnesium 12-hydroxystearate and 30% by weight.
It is preferably composed of 10% by weight of the above zinc 12-hydroxystearate. It is further preferred that the mixture was obtained by coprecipitation.

Further, in the present invention, the above polyethylene 1
It is preferable that 0.03 to 1 part by weight of the above mixture is contained with respect to 00 parts by weight. Furthermore, the above polyethylene 1
You may contain 0.01-1 weight part calcium stearate or 12-hydroxy calcium stearate with respect to 00 weight part.

[0009]

In the resin composition of the present invention, polyethylene is not limited to a polymer of ethylene alone, and ethylene and other α-olefins such as 1-butene, 1-pentene, 1-hexene and 4-methyl-olefin can be used. Includes copolymers with 1-pentene, 1-octene, or any mixture thereof. The method for synthesizing high-density polyethylene that can be used in the present invention is disclosed in, for example, JP-A-49-133488, JP-B-52-13232, and JP-B-62-54326.

The melt index of polyethylene is 0.
It is 01 to 100 g / 10 min. This is JIS K
7210 1976, 190 ° C. under the conditions of Table 4,
It is a value measured under a load of 2.16 kgf. When the melt index is less than 0.01g / 10min.
The melt viscosity is so high that extrusion molding and stretch molding become difficult. On the other hand, when the melt index is more than 100 g / 10 min., The mechanical strength of the stretch-molded product is poor, and when it is molded into fibers, the melt tension during draft spinning is insufficient, and high-speed spinning becomes difficult.

The density of polyethylene is 0.940-
It is 0.970 g / cm ³ . Density is 0.94g / cm ³
When it is less than the above range, the rigidity of the resin composition is insufficient, and the stretchability and strength are poor. On the other hand, when the density exceeds 0.970 g / cm ³ , the stretched material lacks the degree of stretching, and particularly when it is made into a flat yarn, it tends to crack.

In the resin composition of the present invention, 0.01 to 1 part by weight of a mixture of basic magnesium 12-hydroxystearate and zinc 12-hydroxystearate is added to 100 parts by weight of this high-density polyethylene. It By blending this mixture, the transparency of the resin composition can be improved and color unevenness can be prevented. Moreover, 0.03-0.5 parts by weight to 100 parts by weight of this high-density polyethylene,
More preferably, 0.03 to 0.3 parts by weight of the above mixture may be blended.

[0013] Magnesium 12-hydroxystearic acid means a _{(C 17 H 35 (OH)} COO) 2 Mg, also 12-hydroxystearic acid zinc (C ₁₇ H
₃₅ (OH) COO) ₂ Zn. By basic it is meant that in the salt of 12-hydroxystearic acid, which is a carboxylic acid, and magnesium or zinc, which is a metal, the equivalent amount of metal is slightly in excess of the equivalent amount of carboxylic acid. This excess metal is preferably in the oxide or hydroxide form.

The ratio of this mixture in the present invention is 70.
Preferably from 90 to 90% by weight basic magnesium 12-hydroxystearate and 30 to 10% by weight zinc 12-hydroxystearate, 75 to 85% by weight basic 12-hydroxystearate and 25 to 15%. More preferably, it consists of wt% zinc 12-hydroxystearate. This mixture can be coprecipitated from solution to give a precipitate. For example, a solution containing magnesium hydroxide containing 70 to 90% by weight of magnesium atoms and 30 to 10% by weight of zinc atoms and a solution containing zinc hydroxide is suitable for a solution consisting of a suitable solvent and 12-hydroxystearic acid. Any amount can be added, dissolved and then co-precipitated. Also,
An oxide may be used instead of the hydroxide.

Further, with respect to the above high density polyethylene,
Furthermore, it is preferable to contain 0.01 to 1 part by weight of calcium stearate or 12-hydroxy calcium stearate. This is to neutralize chlorine contained in the catalyst residue of high-density polyethylene and to improve slippage when molding the resin composition.

The polyethylene resin composition of the present invention may contain additives such as a resin stabilizer, an antioxidant and an ultraviolet absorber, or a colorant. These additives or colorants may be those usually used in the resin composition for monofilaments. Examples of the resin stabilizer include butylhydroxytoluene (BHT), octadecyl β- (3,5-ditertiarybutyl-4-hydroxy-phenyl) propionate (for example, trade name, IRGANOX 1076 manufactured by Ciba-Geigy Co., Ltd.). Stabilizers such as phenol, or tris (2,4-ditertiarybutyl-
Phenyl) phosphite (for example, Asahi Denka Co., Ltd.)
A phosphorus-based stabilizer such as a trade name of ADK STAB 2112 manufactured by Ciba Geigy Co., Ltd., IRGAFOS 168) manufactured by Ciba-Geigy Co., Ltd. can be used.

[0017]

EXAMPLES The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the following examples.

(Preparation of Solid Catalyst) Methylhydropolysiloxane (40 ml) was gradually added to a tetrahydrafuran solution of n-butylmagnesium chloride (0.670 mol) in a reaction vessel. After adding the whole amount, 7
The mixture was reacted by stirring at 0 ° C for 1 hour. Then, the solution was diluted with toluene and then distilled to remove tetrahydrofuran to obtain a toluene solution of a reaction product.

On the other hand, a reactor equipped with a suitable funnel and a stirrer was prepared, and a solution containing diethylaluminum chloride (45.3 ml) and toluene (815 ml) was kept at 50 ° C. in this reactor. Also, from the appropriate bottom funnel, toluene (153 ml), ethanol (21.0 m
l) and isopropyl alcohol (27.6 ml) were added to the reactor with stirring over 1 hour,
Further, the reaction was carried out at room temperature for 1 hour. Next, toluene (123 ml) and then a toluene solution of the above reaction product (243 ml, containing 0.36 gram atom in terms of magnesium) were added to this reactor, and the mixture was stirred at 60 ° C. for 2 hours. Held in. Next, titanium tetrachloride (198 ml) was put in the reactor for 1 hour, then heated to 95 ° C. and reacted for 2 hours to obtain a slurry. N-Hexane was added to this slurry, and the components dissolved in n-hexane were decanted and filtered to obtain a solid catalyst. 1 g of this solid catalyst contained 66.9 mg of titanium.

(Polymerization of ethylene) Polymerization was carried out using n-hexane as a solvent in the presence of the above solid catalyst and triethylaluminum while continuously introducing ethylene and a small amount of propylene. A high density polyethylene powder having a melt index of 1.0 and a density of 0.950 g / cm ³ was obtained.

Example 1 0.15 parts by weight of an antioxidant, magnesium 12-hydroxystearate (80% by weight) and 12-hydroxystearic acid per 100 parts by weight of this high-density polyethylene powder. 0.05 parts by weight of the coprecipitate with zinc (20% by weight) was blended using a tumbler, and then using a twin-screw granulator (Toshiba Corp., trade name TEM-35B). Granulated at 180 ° C to obtain pellets. As this coprecipitate, the product name EM644Z of Kosei Co., Ltd. was used as it was. EM644Z is
It is a white powder containing about 4.5 wt% Mg, about 2.0 wt% Zn, free 12-hydroxystearic acid up to 2 wt% and water up to 2 wt%. And the melting point is 175 to 185 ° C.

The pellets were press-molded at 180 ° C.,
A test piece was obtained. This test piece was kept in a gear oven at 100 ° C. for 9 days. The color tone (bL) of the test piece was measured before and after holding. As a change in color tone over time, Table 1 summarizes the difference between the color tone before holding and the color tone after holding (ΔbL = bL after holding−bL before holding). The bL value was measured by SM color computer SM-4-CH (manufactured by Suga Test Instruments Co., Ltd.). A large bL value means that the color is more yellow. Further, using a single screw extruder (trade name: TMNH-40-28 manufactured by Tommy Machinery Co., Ltd.), the pellets were dried at a die temperature of 270 ° C. of 16.2 per hour.
Monofilaments were molded with an extrusion rate of kg. The touch of this monofilament was evaluated. Further, this monofilament was drawn 10 times, and the transparency (L) of the drawn yarn was measured. The L value was measured by SM color computer SM-4-CH (manufactured by Suga Test Instruments Co., Ltd.). Note that the smaller the L value, the more transparent. The results are summarized in Table 1. That is, Table 1 summarizes ΔbL indicating the color tone change of the pellet-molded test piece, the feel of the unstretched monofilament, and the transparency (L) of the stretched yarn.

Example 2 Pellets, test pieces and monofilaments were produced in the same manner as in Example 1. However, in Example 2, 0.12 parts by weight of coprecipitate (trade name EM644Z manufactured by Kosei Co., Ltd.) was used instead of 0.05 parts by weight based on 100 parts by weight of high-density polyethylene powder. That is different.

Example 3 Pellets, test pieces and monofilaments were produced in the same manner as in Example 1. However, in Example 3, 0.30 parts by weight of coprecipitate (trade name EM644Z manufactured by Kosei Co., Ltd.) was used instead of 0.05 parts by weight with respect to 100 parts by weight of high-density polyethylene powder. That is different.

Example 4 In the same manner as in Example 1, pellets, test pieces and monofilaments were produced. However, in Example 4, with respect to 100 parts by weight of the high-density polyethylene powder, not only 0.05 parts by weight of the coprecipitate (trade name EM644Z manufactured by Kosei Co., Ltd.) but also 0.20 parts by weight of the steered product was used. The difference is that calcium phosphate (abbreviated as Ca-St in Table 1) was also added.

Example 5 Pellets, test pieces and monofilaments were produced in the same manner as in Example 1. However, in Example 5, 0.10 part by weight of a coprecipitate (trade name EM644Z manufactured by Kosei Co., Ltd.) and 0.10 part by weight of calcium stearate were added to 100 parts by weight of the high-density polyethylene powder. What you did is different.

Comparative Example Pellets, test pieces and monofilaments were produced in the same manner as in Example 1. But,
In Comparative Example 1, a coprecipitate (trade name EM644Z of Kosei Co., Ltd.) was used with respect to 100 parts by weight of the high-density polyethylene powder.
The difference is that 0.25 part by weight of calcium stearate is blended without blending.

[0028]

[Table 1]

By blending a coprecipitate of magnesium 12-hydroxystearate (80% by weight) and zinc 12-hydroxystearate (20% by weight), the surface of undrawn monofilament becomes smooth. Also, the transparency of the drawn yarn was improved. When the transparency is improved, the whiteness of a part on the surface of the extruded product or the stretched product is less likely to be different from the whiteness of other parts. The improved transparency results in a brighter color when colored. Furthermore, the change in color tone was similar to that of the comparative example, and all were favorable.

[0030]

According to the present invention, basic 12-hydroxy magnesium stearate and 1 are added to high density polyethylene.
By blending a mixture of zinc 2-hydroxystearate, transparency and color tone change of the resin composition are improved, and at the same time, when the resin composition is molded or stretched, clogging is less likely to occur. Therefore, it can be continuously molded or stretched over a long period of time.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Soichi Komaki 11 11 Goi Minamikaigan, Ichihara-shi, Chiba Maruzen Polymer Co., Ltd.

Claims (5)

[Claims] 1. A melt index of 0.01 to 100.
g / 10 min. and a density of 0.940 to 0.9
100 parts by weight of polyethylene of 70 g / cm ³ , basic 12-hydroxy magnesium stearate and 1
Mixture of zinc 2-hydroxystearate 0.01-1
And a polyethylene resin composition. 2. The mixture according to claim 1, characterized in that it comprises 70-90% by weight of the basic magnesium 12-hydroxystearate and 30-10% by weight of the zinc 12-hydroxystearate. Polyethylene resin composition. 3. The polyethylene resin composition according to claim 2, wherein the mixture is obtained by coprecipitation. 4. The polyethylene resin composition according to claim 1, wherein 0.03 to 1 part by weight of the mixture is contained with respect to 100 parts by weight of the polyethylene. 5. The polyethylene resin composition according to claim 1, which contains 0.01 to 1 part by weight of calcium stearate or 12-hydroxy calcium stearate with respect to 100 parts by weight of the polyethylene. object.