JP3439794B2 - Polyethylene composition and tube made thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene composition having excellent moldability, flexibility and durability, and a tube comprising the same.

[0002]

2. Description of the Related Art Conventionally, soft vinyl chloride resins and olefin thermoplastic elastomers obtained by blending rubber with polyolefin have been mainly used for flexible pipes, especially hoses. However, the vinyl chloride resin has a problem in recyclability and waste incineration, and the olefin-based thermoplastic elastomer has a problem that the cost is high because an expensive rubber is used. On the other hand, some attempts have been made to use linear low-density polyethylene that is inexpensive and has excellent chemical resistance, but hoses for washing machines and vending machines, in particular, have insufficient flexibility, moldability, and durability. The point is not satisfactory.

[0003]

Particularly, in the case of a hose for a washing machine, in particular, the hose is not only flexible, but also when the hose is molded, a drawdown resistance so that the resin does not drip and become unmoldable, and From the aesthetic viewpoint of the product, it is necessary to have moldability such that the outer surface of the hose is smooth. In addition, recently, there are many cases where a washing machine is installed on the veranda of a condominium such as an apartment, and there are also cases where hot water is used to improve the washing effect. Therefore, durability such as weather resistance and chemical resistance over a long period of time is provided. is necessary. Therefore, the present inventors have found that the linear low density polyethylene has the drawbacks of flexibility, moldability,
It aims to solve the lack of durability by an inexpensive method.

[0004]

Means for Solving the Problems [Outline of the Invention] As a result of various studies on the improvement of the above-mentioned problems, the present inventors have found that a specific polyethylene that may contain a specific ethylene / vinyl acetate copolymer is used. In addition, by adding a specific phenolic antioxidant and a hindered amine compound, a polyethylene composition excellent in flexibility, moldability, and durability, and a tube comprising the same were obtained, and the present invention was completed. It is a thing. That is, the present invention comprises the following components (A) and (B) in a total amount of 100 parts by weight, and components (C) and (D), and has a melt tension of 3 g or more and an Orsen bending rigidity of 3. A polyethylene composition characterized by being 200 kg / cm ² or less, and a tube comprising the same. Component (A): Linear low density polyethylene having a MFR of 0.2 to 1 g / 10 minutes, a density of 0.930 g / cm ³ or less, and a melt tension of 4 g or more 100 to 50 parts by weight (B) Component: MFR is 0.3 to 5 g / 10 minutes, ethylene / vinyl acetate copolymer having a vinyl acetate content of 10% by weight or more 0 to 50 parts by weight (C) component: a phenolic antioxidant having a molecular weight of 650 or more 0.03 to 1 part by weight (D) component: hindered amine compound having a molecular weight of 2,000 or more 0.03 to 1 part by weight

[Detailed Description of the Invention] [I] Polyethylene composition (1) Constituent component (a) Linear low-density polyethylene The linear low-density polyethylene used as the component (A) in the polyethylene composition of the present invention is It is an ethylene / α-olefin copolymer obtained by copolymerizing ethylene and α-olefin using an ionic polymerization catalyst. As the α-olefin as a comonomer,
An α-olefin having about 3 to 20 carbon atoms may be mentioned. Preferred α-olefins are butene-1, hexene-
These are 1,4-methylpentene-1 and octene-1. The copolymerization of ethylene with these α-olefins can be carried out by a gas phase method, a solution method, a slurry method, a high pressure method or the like using a single tank or two or more reaction tanks continuously.

A preferable ionic polymerization catalyst for this linear low-density polyethylene is one obtained by supporting chromium oxide on an inorganic carrier such as silica / alumina or the like, which gives a broad molecular weight distribution even by single tank polymerization, that is, a chromium oxide type. It is a Phillips type catalyst. The linear low density polyethylene used here has an MFR of 0.2 to 1 g / 10 minutes, preferably 0.4 to 0.8 g / 10 minutes. If the MFR is lower than the above range, there is a drawback that the outer surface of the hose is poor in smoothness. On the other hand, if the MFR is higher than the above range, when the hose is molded, the melt tension, which is a measure of drawdown property, becomes low and the durability becomes poor. Density is 0.930g / c
m ³ or less, preferably 0.925 g / cm ³ or less, and the lower limit of the current technology is 0.88 g / cm ³ from the viewpoint of manufacturing. If the density is higher than the above range, there is a drawback that flexibility is poor. The melt tension is 4 g or more, preferably 5 g or more, but the upper limit is about 15 g in terms of balance with MFR. If the melt tension is lower than the above range, there is a drawback that the resin drips when molding the hose and molding becomes difficult.

The above MFR is JIS-K7210.
Temperature 1 according to (flow test method for thermoplastics)
It is a value measured at 90 ° C. The above density is JIS-
It is a value measured by K6760 (polyethylene test method). Further, the melt tension is M of JIS-K7210.
Using a furnace and nozzle used in the FR measurement method, a temperature of 19
When the resin in the furnace is extruded in a strand shape at 0 ° C and a speed of 1 cm / min and passed through a pulley for tension detection and pulled at a speed of 4 m / min, the force applied to the pulley is measured. is there.

(B) Ethylene / Vinyl Acetate Copolymer The ethylene / vinyl acetate copolymer used as the component (B) in the polyethylene composition of the present invention has a pressure of 500 to 5,000 kg / cm ² , and a temperature of 100 to 100. 35
A normal high-pressure ethylene / vinyl acetate copolymer obtained by copolymerizing ethylene and vinyl acetate at 0 ° C. with a radical generator such as oxygen or organic peroxide is used. The ethylene / vinyl acetate copolymer used here has an MFR of 0.3 to 5 g / 10 min, preferably 1 to 3
g / 10 minutes. If this MFR is lower than the above range, there is a drawback that the outer surface of the hose is inferior in smoothness. On the other hand, if the MFR is higher than the above range, when the hose is molded, the melt tension, which is a measure of drawdown property, becomes low and the durability becomes poor. Vinyl acetate content is 10% by weight
The above is preferably 15% by weight or more, but the upper limit is about 40% by weight from the viewpoint of manufacturing, which is the limit of the current technology. If the vinyl acetate content is too low, there is a drawback that flexibility and durability are poor. The mixing ratio of the ethylene / vinyl acetate copolymer is 0 to 50 parts by weight, preferably 1 to 50 parts by weight, and particularly preferably 10 parts by weight based on 100 parts by weight of the linear low density polyethylene and the total thereof. ~ 40 parts by weight. If the blending ratio is too large, there is a problem that durability is deteriorated. The vinyl acetate content is JIS-K6730.
It is a value measured by (Ethylene / vinyl acetate resin test method).

(C) Phenolic Antioxidant The phenolic antioxidant used as the component (C) in the polyethylene composition of the present invention has a molecular weight of 65.
0 or more is used. Specifically, pentaerythyl-tetrakis [3- (3,5-di-t-butyl-4]
-Hydroxyphenyl) propionate], 1,3,5
-Trimethyl-2,4,6-tris (3,5-di-t-
Butyl-4-hydroxybenzyl) benzene, bis (3,5-di-t-butyl-4-hydroxybenzylphosphonate ethyl) calcium, tris- (3,5-di-
t-butyl-4-hydroxybenzyl) -isocyanurate and the like. The preferred phenolic antioxidant is 1,3,5-trimethyl-2,
Mention may be made of 4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene. It is considered that the reason is that it has no ester structure and therefore does not hydrolyze even when it comes into contact with hot wastewater. The preferred molecular weight of the phenolic antioxidant used here is 700 or more. If the molecular weight is lower than the above range, there is a problem that the antioxidant is extracted into water and the antioxidant effect is poor. The blending ratio of the phenolic antioxidant is 0.03 to 1 part by weight, preferably 0.05 to 0. 0, based on 100 parts by weight of the total of the linear low density polyethylene and the ethylene / vinyl acetate copolymer. 3 parts by weight. If this blending ratio is too small, there is a problem that durability is poor. On the other hand, if the amount is too large, the effect is saturated and the cost increases.

(D) Hindered amine compound The hindered amine compound used as the component (D) in the polyethylene composition of the present invention has a molecular weight of 2,
000 or more is used. Specifically, dimethyl succinate-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, poly [{6- (1,1,3,3 -Tetramethylbutyl) imino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6 6-Tetramethyl-4-piperidyl) imino}], N, N'-bis (3-aminopropyl) ethylenediamine-2,4-
Bis [N-butyl-N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,
3,5-triazine condensate and the like can be mentioned. The preferred hindered amine compound is poly [{6
-(1,1,3,3-tetramethylbutyl) imino-
1,3,5-triazine-2,4-diyl} {(2,
2,6,6-Tetramethyl-4-piperidyl) imino}
Hexamethylene {(2,2,6,6-tetramethyl-4
-Piperidyl) imino}]. The preferred molecular weight of the hindered amine compound used here is 2,500 or more. If the molecular weight of this hindered amine compound is lower than the above range, there is a problem that the hindered amine compound is extracted into water and the ultraviolet ray prevention effect and the antioxidant effect are poor. The blending ratio of the hindered amine compound is 0.03 to 1 part by weight, preferably 0.05 to 0.3 part by weight based on 100 parts by weight of the total of the linear low density polyethylene and the ethylene / vinyl acetate copolymer.
Parts by weight. If this blending ratio is too small, there is a problem that durability is poor. On the contrary, if the mixing ratio is too large, the effect is saturated and the cost becomes high.

(2) Production of polyethylene composition (a) Blending and kneading The above-mentioned linear low density polyethylene (A) component, ethylene / vinyl acetate copolymer (B) component, and phenolic (C) component The method of blending the antioxidant and the hindered amine compound of the component (D) to obtain a polyethylene composition is a method of kneading with a kneader such as a roll, a Banbury mixer, a kneader, an extruder, a Henschel type mixer, a V blender. Ordinary methods such as dry blending with a dry blender such as a tumbler can be applied. To this composition, further additives such as other antioxidants, neutralizing agents, lubricants, anti-blocking agents, antistatic agents, ultraviolet absorbers, etc., carbon black, organic pigments, inorganic pigments, etc. If necessary, a small amount of resin for adding a colorant and these additives, a colorant and the like as a masterbatch can be blended. Alternatively, another resin or rubber may be contained within a range that does not significantly impair the effects of the present invention.

(B) Physical Properties of Polyethylene Composition The melt tension of this polyethylene composition is 3 g or more, preferably 4 g or more, but the upper limit is about 15 g in view of balance with MFR. If this melt tension is lower than the above range, there is a problem that the resin forming the hose hangs and molding becomes difficult. The polyethylene composition has an Orzen flexural rigidity of 3,200 kg / cm ² or less, preferably 2,000 kg / cm ² or less, but if it is too low, the tube itself loses its self-sustaining property, and therefore 1,000 kg / c.
The limit is about m ² .

[II] Pipe Made of Polyethylene Composition (1) Molding The above-mentioned polyethylene composition is subjected to a conventional molding method to manufacture a pipe. (2) Examples of shaped pipes include pipes such as water supply pipes, water distribution pipes, and chemical transfer pipes, and hose-shaped pipes, but any pipe that allows passage of fluid can be applied. Especially, the effect is greatly exerted for outdoor use. A preferable example of the polyethylene composition pipe is a hose for a washing machine. The reason for this is that the hose of the washing machine is not only flexible, but also has a draw-down property that prevents the resin from dripping when molding the hose, and the outer surface of the hose is smooth in terms of product aesthetics. Moldability is required. In addition, recently, there are many cases where a washing machine is installed on the veranda of a condominium such as an apartment, and there are also cases where hot water is used to improve the washing effect. Therefore, durability such as weather resistance and chemical resistance for a long time is provided. This is because it is necessary.

[0014]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples below. The additives and evaluation methods used in the following Examples and Comparative Examples are as shown below. [I] Additive (1) Phenolic antioxidant * 1: 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl)
Benzene * 3: Pentaerythyl-tetrakis [3- (3,5
-Di-t-butyl-4-hydroxyphenyl) propionate] * 4: Bis (3,5-di-t-butyl-4-hydroxybenzylphosphonate ethyl) calcium * 5: Tris- (3,5-di- t-butyl-4-hydroxybenzyl) -isocyanurate * 8: octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate

(2) Hindered amine compound * 2: poly [{6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diyl} {(2,2 , 6,6-Tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}] * 6: Dimethyl-1- (2-hydroxyethyl succinate) ) -4-Hydroxy-2,2,6,6-tetramethylpiperidine polycondensate * 7: N, N'-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- ( 1,
2,2,6,6-Pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate * 9: bis (2,2,6,6-tetramethyl-4-piperidyl) Sebacate

[II] Experimental Examples Examples 1 to 18 and Comparative Examples 1 to 12 (1) Composition Additives were added to the resins shown in Tables 1 to 5, and the temperature was measured with a single screw extruder having a screw diameter of 50 mm. 200 ° C, rotation speed 80
The resin was kneaded under the conditions of rpm to obtain pellets.

(2) Molding The above-mentioned compound is put in a tube forming machine having a screw diameter of 40 mm,
While inflating the tube with air pressure so that the outer diameter was 15 mm and the inner diameter was 14 mm, the tube was molded at a rate of an extrusion rate of 12 kg / hr.

(3) Evaluation (a) Dripping property The dripping condition of the molten resin during the molding was visually observed and judged. The criteria for judgment are as follows. ◎: Very good (no dripping) ○: Good (slightly dripping but no problem in molding) ×: Bad (dripping)

(B) Appearance The irregularities on the outer surface of the tube obtained by the above molding were visually observed and judged. The criteria for judgment are as follows. ◎: Very good (very smooth) ○: Good (smooth) ×: Poor (having irregularities)

(C) Flexibility A pellet having a thickness of 2 mm was produced from the pellet obtained by the above single-screw extruder with a compression molding machine heated to 160 ° C., and the Olsen bending rigidity was measured by ASTM-D747. .

(D) Durability acceleration test The tube obtained by the above molding was irradiated with a carbon arc sunshine weather meter at 73 ° C. for 1,000 hours,
Take out this tube and run it under hot water at 60 ° C on both the inside and outside surfaces.
After immersing for 000 hours, the tube was returned to the sunshine weather meter again, and irradiation of the sunshine weather meter was repeated 3 times in total, and immersion in warm water was repeated 2 times in total. After these treatments, the deterioration state of the tube was visually observed and judged. The criteria for judgment are as follows. ◎: Very good (no deterioration at all) ○ ⁺ : Quite good (almost no deterioration) ○: Good (no problem) △: Somewhat bad (somewhat deteriorated) ×: Bad (degraded) × ×: Very bad (very Deterioration)

(E) ESCR (Environmental Stress Cracking Time with Constant Strain) Pellets obtained by the above-mentioned single-screw extruder were heated to 160 ° C. to form a press sheet having a thickness of 2 mm by a compression molding machine, and JIS- The constant stress environmental stress cracking time was measured by K6760. The evaluation results of the obtained tubes are shown in Tables 1-5.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

[Table 4]

[0027]

[Table 5]

[0028]

INDUSTRIAL APPLICABILITY According to the present invention, a polyethylene composition which is extremely excellent in flexibility, moldability and durability than conventional polyethylene is obtained by blending a specific phenolic antioxidant and a specific hindered amine compound with a specific polyethylene. It is possible to obtain an object and a tube made of it.

Claims (8)

(57) [Claims] 1. The total of the following components (A) and (B) is 1
00 parts by weight and (C) component and (D) component, and has a melt tension of 3 g or more and an Orsen flexural rigidity of 3.
A polyethylene composition, which is 200 kg / cm ² or less. Component (A): Linear low density polyethylene having a MFR of 0.2 to 1 g / 10 minutes, a density of 0.930 g / cm ³ or less, and a melt tension of 4 g or more 100 to 50 parts by weight (B) Component: MFR is 0.3 to 5 g / 10 minutes, ethylene / vinyl acetate copolymer having a vinyl acetate content of 10% by weight or more 0 to 50 parts by weight (C) component: a phenolic antioxidant having a molecular weight of 650 or more 0.03 to 1 part by weight (D) component: hindered amine compound having a molecular weight of 2,000 or more 0.03 to 1 part by weight [here, melt tension is measured by MFR of JIS-K7210]
Using a furnace and nozzle used in the conventional method, a temperature of 190
℃, strike the piston rod at a speed of 1 cm / min
Push it out like a land and pass it through a pulley for tension detection.
When pulling at a speed of 4 m / min, add it to the pulley.
The force for measuring the Orsen bending rigidity is 2 mm
Measured by TM-D747, MFR is JIS-K7210 (thermoplastic
Flow test method) at a temperature of 190 ° C.
The density is according to JIS-K6760 (polyethylene test method).
The vinyl acetate content was measured according to JIS-K6730 (ethylene / vinegar).
Vinyl acetate resin test method)
It ] 2. The polyethylene composition according to claim 1, wherein the linear low density polyethylene as the component (A) is a linear low density polyethylene obtained by a chromium oxide type Phillips type catalyst. 3. A phenolic antioxidant as component (C) is 1,3,5-trimethyl-2,4,6-tris (3,5).
A polyethylene composition according to claim 1 or 2, which is -di-t-butyl-4-hydroxybenzyl) benzene. 4. A hindered amine compound as the component (D) is dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate and / or poly [{ 6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-
2,4-diyl} {(2,2,6,6-tetramethyl-
4-piperidyl) imino} hexamethylene {(2,2,
6,6-Tetramethyl-4-piperidyl) imino}], The polyethylene composition according to any one of claims 1 to 3. 5. The total of the following components (A) and (B) is 1
00 parts by weight and (C) component and (D) component, and has a melt tension of 3 g or more and an Orsen flexural rigidity of 3.
A tube comprising a polyethylene composition having a weight of 200 kg / cm ² or less. Component (A): Linear low density polyethylene having a MFR of 0.2 to 1 g / 10 minutes, a density of 0.930 g / cm ³ or less, and a melt tension of 4 g or more 100 to 50 parts by weight (B) Component: MFR is 0.3 to 5 g / 10 minutes, ethylene / vinyl acetate copolymer having a vinyl acetate content of 10% by weight or more 0 to 50 parts by weight (C) component: a phenolic antioxidant having a molecular weight of 650 or more 0.03 to 1 part by weight (D) component: hindered amine compound having a molecular weight of 2,000 or more 0.03 to 1 part by weight [here, melt tension is measured by MFR of JIS-K7210]
Using a furnace and nozzle used in the conventional method, a temperature of 190
℃, strike the piston rod at a speed of 1 cm / min
Push it out like a land and pass it through a pulley for tension detection.
When pulling at a speed of 4 m / min, add it to the pulley.
The force for measuring the Orsen bending rigidity is 2 mm
Measured by TM-D747 , MFR is JIS-K7210 (thermoplastic
Flow test method) at a temperature of 190 ° C.
The density is according to JIS-K6760 (polyethylene test method).
The vinyl acetate content was measured according to JIS-K6730 (ethylene / vinegar).
Vinyl acetate resin test method)
It ] 6. The pipe according to claim 5, wherein the linear low density polyethylene as the component (A) is a linear low density polyethylene obtained by a chromium oxide type Phillips type catalyst. 7. The (C) component phenolic antioxidant is 1,3,5-trimethyl-2,4,6-tris (3,5).
A tube according to claim 5 or 6 which is -di-t-butyl-4-hydroxybenzyl) benzene. 8. A hindered amine compound as the component (D) is a polycondensation product of dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine succinate and / or poly [{ 6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-
2,4-diyl} {(2,2,6,6-tetramethyl-
4-piperidyl) imino} hexamethylene {(2,2,
6,6-Tetramethyl-4-piperidyl) imino}], The tube according to any of claims 5-7.