JPH10219044A - Polyolefin resin composition for vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition giving excellent mold release effect in injection molding without lowering of resistance to stress cracking by containing a specific high-density polyethylene resin and aliphatic acid dialkanolamides in a specific ratio. SOLUTION: This composition contains (A) 100 pts.wt. of a high-density polyethylene resin having 3-50g/10min melt flow rate (at 190 deg.C, under 21.18N) and (B) 0.05-1.00 pt.wt. of aliphatic acid dialkanolamides. The component A is, e.g. a crystalline ethylene homopolymer, a crystalline ethylenic copolymer of ethylene and propylene or ethylene and butene-1 or their mixture in using ethylene as a main component (containing >=50wt.% of ethylene unit) and preferably has 0.941-0.970g/cm<3> density. Preferably, the component B is diethanolamide laurate, etc. The composition can comfortably be applied to an injection molded product for a vessel of pickles of vegetable, meat or fish, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin resin composition for containers suitable for injection molding with improved stress cracking properties. More specifically, the present invention relates to a polyolefin resin composition for a container, which is obtained by blending a specific amount of a fatty acid dialkanolamide with a high-density polyethylene resin having a specific melt flow rate and molding the mixture by an injection molding method. The present invention relates to a polyolefin resin composition for containers suitable for injection molding, which has a shape effect and improves cracking by preventing stress crack reduction.

[0002]

2. Description of the Related Art As a method for obtaining a molded article having a good mold releasing effect at the time of molding by injection molding using a polyolefin-based resin, a polypropylene resin or a high-density polyethylene resin is added to an antistatic agent, glycerin monoester. A method of adding a stearate type or an alkylamine type is known.

However, when a container composition in which a glycerin monostearate or an alkylamine as an antistatic agent is added to a known high-density polyethylene resin is used, molding is possible and a good mold release effect is obtained at the time of molding. However, there is a disadvantage that cracking of the molded article due to stress cracks is remarkably reduced and the product life is shortened. And the technique which can improve this defect is not disclosed as far as the present inventor knows.

[0004]

DISCLOSURE OF THE INVENTION The present inventors have intensively studied to obtain an excellent high-density polyethylene resin for containers which has a good mold releasing effect at the time of molding and does not reduce stress cracks. As a result, when molded with a composition obtained by adding a fatty acid dialkanolamide to a high-density polyethylene resin having a specific melt flow rate, a good mold release effect is obtained at the time of molding, and the stress cracking property is not significantly reduced. A stable polyolefin resin composition for containers was found, and the present invention was completed based on this finding. As is apparent from the above description, an object of the present invention is to provide a polyolefin resin composition for containers which has a good mold releasing effect by injection molding and does not reduce stress cracking properties, and is made of vegetables, fruits, It can be suitably used for injection molded articles such as containers for pickles such as meat and fish, and miso containers.

[0005]

The present invention has the following arrangement.

(1) Melt flow rate (190 ° C. 2
1.18N) 100 parts by weight of a high-density polyethylene resin of 3 to 50 g / 10 min.
A polyolefin resin composition for containers comprising from 0.05 to 1.00 parts by weight.

(2) The high-density polyethylene resin is an ethylene homopolymer or a copolymer composed of either propylene or butene-1 containing ethylene as a main component and having a density of 0.941 to 0.970 g / The polyolefin resin composition for containers according to the above (1), wherein the composition is cm ³ .

(3) The polyolefin resin composition for containers according to the above (1) or (2), which is for injection molding.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The high-density polyethylene resin used in the present invention has a melt flow rate (190 ° C. 21.18 N) of 3 to 50 g in view of fluidity and molding stability.
/ 10 minutes, preferably 5 to 20 g / 10 minutes, a high-density polyethylene resin, for example, crystalline ethylene homopolymer, ethylene as a main component (ethylene unit 50% by weight or more,
(Preferably 70% by weight or more), a crystalline ethylene-based copolymer of ethylene and propylene or ethylene and butene-1, and a mixture thereof. In addition, the fatty acid dialkanolamides used in the present invention are 0.05 to 1.
00 parts by weight, preferably 0.20 to 0.60 parts by weight. If the amount used is less than 0.05 parts by weight, the effect is poor,
Even if the amount exceeds 1.00 part by weight, there is no particular increase in the effect.

The polyolefin resin composition for containers of the present invention contains linear low-density polyethylene and ethylene-propylene rubber in a range that does not impair the effects of the present invention, that is, in a range of less than 50% by weight, preferably 30% by weight or less. , Styrene-butadiene rubber, polyvinyl acetate, ethylene-
Vinyl acetate copolymer and its partially saponified products, inorganic fillers (talc, mica, glass fiber, wollastonite, zeolite, calcium carbonate, magnesium hydroxide, etc.),
Light stabilizers, phenolic, phosphorus and sulfur antioxidants, neutralizing agents such as higher fatty acid calcium, antiblocking agents, clarifying agents, nucleating agents, radical generators and various coupling agents (silanes, titanates System, boron system, aluminate system) can be used in combination.

The polyolefin resin composition for containers of the present invention has a melt flow rate (190 ° C. 21.18 N) of 3
A predetermined mixing amount of the high-density polyethylene resin, fatty acid dialkanolamides and the above-mentioned various additives of ５０50 g / 10 min. , Etc., and the mixture is melt-kneaded at a temperature of 160 to 300 ° C., preferably 180 to 250 ° C. using a single-screw or twin-screw extruder or roll.
And melt-kneading pelletizing.

The fatty acid dialkanolamides used in the composition of the present invention include behenic acid diethanolamide, oleic acid diethanolamide, stearic acid diethanolamide, myristic acid diethanolamide, lauric acid diethanolamide, capric acid diethanolamide, and caprylic acid. Acid diethanolamide and the like,
Particularly, lauric acid diethanolamide is preferred. The compounding ratio of the fatty acid dialkanolamide is 0.05 to 1.00 parts by weight, more preferably 0.20 to 1.00 part by weight, based on the composition.
It is 0.60 parts by weight, and two or more fatty acid dialkanolamides can be used alone or in combination. If the amount is less than 0.05 part by weight, the mold releasing effect at the time of molding is small, and if it exceeds 1.00 part by weight, the mold releasing effect is saturated and the stress cracking property is undesirably reduced.

[0013]

EXAMPLES The present invention will now be described specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. The evaluation method used in the examples and comparative examples was based on the following method. 1) Melt flow rate (190 ° C. 21.18N):
Conforms to JIS K6760. 2) Mold release effect: A box-shaped molded product having a width of 115 mm, a length of 230 mm, a height of 120 mm, a thickness of 2 mm and a draft angle of 0.5 ° is formed by an air ejection method, and an air pressure of 2 kg.
Good when released at less than / cm ² , air pressure 2kg
When the mold was released at a rate of / cm ² or more, it was indicated as defective. 3) Stress cracking: constant strain environment stress crack test,
In accordance with JIS K6760, the surfactant solution was a commercially available 2% solution of mama lemon (trade name), and the determination was made based on the retention of stress cracking property, and the glycerin monostearate, alkylamine or fatty acid dialkanolamide of the base material was used. Stress cracking time of non-added products is 10
0%, the retention rate of 60% or more was indicated as good, and the retention rate of less than 60% was indicated as defective.

Examples 1 to 4 and Comparative Examples 1 to 6 In Examples 1 to 4, a melt flow rate (190 ° C. 21.18 N) 10 g / 1 as a high-density polyethylene resin.
For 0 minutes, 100 parts by weight of ethylene homopolymer pellets (PE resin 1) having a density of 0.961 g / cm ³ were mixed with 0.05, 0.30, 0.60 lauric acid diethanolamide (amide) of fatty acid dialkanolamides. 1.00 parts by weight, and n-octadecyl-β- (4′-
0.03 parts by weight of hydroxy-3 ′, 5′-di-t-butylphenyl) propionate (anti-ferric acid);
10 parts by weight were placed in a tumbler mixer at the mixing ratio shown in Table 1 below and mixed for 10 minutes. Then, the mixture was melted and kneaded at a melt kneading temperature of 2 using a single-screw extruder having a diameter of 45 mm.
Extruded and pelletized at 20 ° C. Comparative Examples 1 to 6
In Comparative Examples 1 to 3, 100 parts by weight of an ethylene homopolymer pellet (PE resin 1) having a melt flow rate (190 ° C. 21.18 N) of 10 g / 10 min and a density of 0.961 g / cm ³ as a high-density polyethylene resin was used. Glycerin monostearate (anti-banding agent A) alone 0.05,
0.30, 0.60 parts by weight, n-octadecyl-β- (4′-hydroxy-3 ′, 5′-di-
t-butylphenyl) propionate (protected from felic acid)
03 parts by weight, a neutralizing agent 0.10 parts by weight, and N, N bis (2-hydroxyethyl) fat (C8-C1
8) 0.05 (0.30) of amine (anti-banding agent B) alone,
0.60 parts by weight, n-octadecyl- as an antioxidant
0.03 parts by weight of β- (4′-hydroxy-3 ′, 5′-di-t-butylphenyl) propionate (anti-ferric acid) and 0.10 parts by weight of the neutralizing agent are shown in Tables 1 and 2 below. The mixture was placed in a tumbler mixer at the mixing ratio described, mixed for 10 minutes, and then melt-kneaded and pelletized according to Examples 1 to 4. Using the pellets obtained in each of the examples and comparative examples, the mold release effect and the stress cracking property were evaluated. The results are summarized in Tables 1 and 2.

[0015]

[Table 1]

[0016]

[Table 2]

Comparative Examples 7 to 10 Comparative examples 7 to 10 were tested to clarify the effect of the embodiment. In Comparative Example 7, as the high-density polyethylene resin, a melt flow rate (190 ° C. 21.18 N) of 10
g / 10 minutes, 100 parts by weight of ethylene homopolymer pellets (PE resin 1) having a density of 0.961 g / cm ³ were added with n-octadecyl-β- (4′-hydroxy-) as an antioxidant.
3 ′, 5′-di-t-butylphenyl) propionate (anti-ferric acid) 0.03 parts by weight and a neutralizing agent 0.10 parts by weight, and Comparative Examples 8 to 10 used as a high-density polyethylene resin as a melt flow rate (190 ° C 21.18N) 10
g / 10 minutes, 100 parts by weight of ethylene homopolymer pellets (PE resin 1) having a density of 0.961 g / cm ³ were lauric acid diethanolamide (amide) alone 0.01,
0.03, 1.50 parts by weight and n-octadecyl-β- (4′-hydroxy-3 ′, 5′-di-
t-butylphenyl) propionate (protected from felic acid)
03 parts by weight and 0.10 parts by weight of the neutralizing agent were placed in a tumbler mixer at the mixing ratio shown in Table 2 below, and mixed for 10 minutes. Then, the mixture was melt-kneaded and pelletized according to Comparative Examples 1 to 6. Using the pellets obtained in Comparative Examples, the mold release effect and the stress cracking property were evaluated. The results are summarized in Table 2.

Example 5 As a high-density polyethylene resin, a melt flow rate (190 ° C., 21.18 N) 3 g / 10 min, density 0.9
To 100 parts by weight of an ethylene homopolymer pellet (PE resin 2) of 61 g / cm ³ , 0.30 parts by weight of lauric acid diethanolamide (amide) and n-octadecyl-β- (4′-hydroxy-3) as an antioxidant were used. ', 5'-Di-t-butylphenyl) propionate
0.03 parts by weight and 0.10 parts by weight of the neutralizing agent were mixed.

Example 6 As a high-density polyethylene resin, a melt flow rate (190 ° C., 21.18 N) 50 g / 10 minutes, and a density of 0.1 were used.
961 g / cm ³ ethylene homopolymer pellets (PE
Resin 3) 0.30 part by weight of lauric acid diethanolamide (amide) per 100 parts by weight of n-octadecyl-β- (4′-hydroxy-3 ′, 5′-di-t-butylphenyl) as an antioxidant Propionate (feic acid protection)
0.03 parts by weight and 0.10 parts by weight of the neutralizing agent were mixed.

Example 7 As a high-density polyethylene resin, a melt flow rate (190 ° C., 21.18 N) of 10 g / 10 minutes and a density of 0.
953 g / cm ³ of ethylene-butene-1 copolymer pellet (PE resin 4) (100 parts by weight), 0.30 part by weight of lauric acid diethanolamide (amide) and n-octadecyl-β- (4 ′) as an antioxidant -Hydroxy-
0.03 parts by weight of 3 ′, 5′-di-t-butylphenyl) propionate (anti-ferric acid) and 0.10 part by weight of a neutralizing agent were mixed.

Example 8 A melt flow rate (1) was used as a high-density polyethylene resin.
90 ° C. 21.18 N) 10 g / 10 min, density 0.96
Melt flow rate (190 ° C. 21.18 N) 1 was added to 100 parts by weight of 1 g / cm ³ ethylene homopolymer pellets.
0 g / 10 min, 0.30 parts by weight of lauric acid diethanolamide (amide) was added to a blend (PE resin 5) of 15 parts by weight of a low density polyethylene resin having a density of 0.920 g / cm ³ and n-octadecyl as an antioxidant -Β- (4 '
-Hydroxy-3 ', 5'-di-t-butylphenyl)
0.03 parts by weight of propionate (ferric acid protection) and 0.10 parts by weight of a neutralizing agent were mixed. Using the pellets obtained in each of the examples, the mold release effect and the stress cracking property were evaluated. The results are shown in Table 2.

As is apparent from Table 1, the molded articles obtained in Examples 1 to 4 using the polyolefin resin composition for containers of the present invention have excellent mold releasing effect and stress cracking property. However, molded articles obtained from the resin compositions of Comparative Examples 1 to 6 in which glycerin monostearate-based or alkylamine-based antistatic agents deviated from the scope of the present invention were used. One of the cracking properties is defective. Further, Comparative Example 7 shown in Table 2 had no mold releasing effect because the lauric acid diethanolamide of the present invention was not added, and Comparative Examples 8 and 9 used the lauric acid diethanolamide (amide) of the present invention. But
Since the compounding amount is less than the range of the present invention, the obtained molded product has good stress cracking property, but has a poor mold releasing effect. Comparative Example 10 uses the lauric acid diethanolamide of the present invention. However, since the compounding amount is out of the range of the present invention, the mold release effect of the obtained molded product is good, but the stress cracking property is low. Getting worse. Examples 5 and 6 in Table 2
As is clear from the figure, the melt flow rate of the high-density polyethylene resin (190 ° C. 21.18 N) was 3 g / 10
Even if the density is 0.961 g / cm ³ , the melt flow rate (190 ° C. 21.18 N) is 50 g / 10 min, and the density is 0.961 g / cm ³ , the compounding amount of lauric acid diethanolamide (amide) is the same as that of this patent. There is no change in the effect within the range. Even if the high-density polyethylene resin ethylene copolymer is used in Example 7, the effect of the present invention is not impaired. Further, it was confirmed in Example 8 that the effects of the present invention were not impaired even if a low-density polyethylene resin was mixed, provided that the compounding amount of lauric acid diethanolamide (amide) was within the range of the present patent. As is clear from the above description, the injection-molded article using the polyolefin resin composition for a container of the present invention is a molded article having a good mold releasing effect and a stress cracking property. Pickled vegetables containers such as Chinese cabbage and Nozawana, fruits,
It is possible to obtain a molded article which gives a container excellent in mold releasing effect and stress cracking property to various injection containers such as a pickle container such as meat and fish and a miso container.

[0023]

As described above, when the polyolefin resin composition for a container of the present invention is injection-molded, an excellent mold releasing effect is obtained, and the obtained molded product is a container with significantly improved stress cracking properties. Therefore, the practical value in a specific application is great.

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI B29L 22:00

Claims (3)

[Claims] 1. Melt flow rate (190 ° C. 21.
18N) 100 parts by weight of high density polyethylene resin of 3 to 50 g / 10 min, fatty acid dialkanolamides 0.05
A polyolefin resin composition for a container comprising from 1.00 to 1.00 parts by weight. 2. The high-density polyethylene resin is an ethylene homopolymer or a copolymer composed of either propylene or butene-1 containing ethylene as a main component, and has a density of 0.941 to 0.970 g / cm. ^{3. The} polyolefin resin composition for containers according to claim 1, which is ³ . 3. The polyolefin resin composition for containers according to claim 1, which is for injection molding.