JPH0940815A - Polyethylene resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition composed of a polyethylene resin, a resin produced by the irradiation of a polyethylene resin with ionizing radiation and a nucleation agent, etc., having excellent transparency and good moldability and appearance and useful as a packaging material, etc. SOLUTION: The objective composition is produced by compounding (A) 100 pts.wt. of a resin composed of (a) 50-99wt.% of a polyethylene resin and (b) 1-50wt.% of a treated resin produced by irradiating a polyethylene resin with ionizing radiation with (B) one or more components selected from (i) 0.05-0.7 pts.wt. of a nucleation agent, (ii) 0.01-0.5 pts.wt. of lithium carbonate and (iii) 0.1-50 pts.wt. of an ethylene-acrylamide resin. Preferably, the component (ii) is an alkali metal phosphate [e.g. sodium-2,2-methylene-bis(4,6-di-t-butylphenyl) phosphate] and the component (iii) contains ethylene units and 0.01-50wt.% of an acrylamide compound.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyethylene resin composition having excellent transparency and good appearance.

[0002]

2. Description of the Related Art Polyethylene resins are generally inexpensive and take advantage of mechanical strength, heat resistance, surface gloss, chemical resistance, oil resistance, rigidity, bending fatigue resistance, etc.
It is molded by injection molding and is widely used in the industrial field. However, the polyethylene-based resin has a drawback that it is inferior in transparency as compared with other resins, such as polypropylene, and is often limited to applications in which transparency is required. As a method for improving this, for example, a method of adding a dibenzylidene sorbitol derivative (JP-A-53-117044, JP-A-58-85632, etc.) or a method of adding the sorbitol and an aliphatic amine (special JP-A-58-180542 and U.S. Pat. No. 4,410,649) have been proposed.

[0003]

However, although the above method can improve the transparency to some extent, it is still insufficient, and it may cause burns or kogation of the molded product depending on the molding conditions, resulting in a remarkable appearance. Often damages. The present invention has been made in view of such circumstances,
It is an object of the present invention to provide a polyethylene resin having excellent transparency and a good appearance.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have blended a polyethylene resin and a polyethylene resin with a resin treated by ionizing radiation and a nucleating agent or an ethylene-acrylamide resin. By
It has been found that the above object can be achieved, and the present invention has been completed based on this finding.

That is, the present invention relates to (C) with respect to 100 parts by weight of a resin component consisting of (A) 50 to 99% by weight of a polyethylene resin and (B) 1 to 50% by weight of a resin obtained by irradiating a polyethylene resin with ionizing radiation. It is intended to provide a polyethylene-based resin composition containing at least one selected from the group consisting of a nucleating agent, lithium carbonate and an ethylene-acrylamide resin.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The polyethylene resin (A) in the present invention includes high density polyethylene, medium / low density polyethylene, linear low density polyethylene, ethylene and α-olefin having 3 to 20 carbon atoms. And a copolymer thereof. Specific examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 4-methylpentene-1, vinylcyclopentane and vinylcyclohexane. The copolymerization ratio with these α-olefins is at most 10% by weight.
And preferably 6% by weight or less. These α-
The olefin may be one kind or a mixture of two or more kinds. Melt Fluorate (Measured under Table 1, Condition 4 according to JIS K7210, "hereinafter referred to as MFR")
Is usually from 0.05 to 150 g / 10 minutes, from 0.1 to
100 g / 10 min is preferred.

The resin-treated product (B) in the present invention is a product obtained by subjecting the polyethylene resin as the component (A) to irradiation treatment with ionizing radiation. The polyethylene resin has an MFR of usually 1 to 300 g / 10 minutes and 2 to 200
g / 10 minutes is preferable, and 3 to 100 g / 10 minutes is particularly preferable. When the MFR is 1 g / 10 min or less, the MFR may be lowered and partly gelled when irradiated with ionizing radiation, and even if it is made into a composition, the moldability is poor and the appearance of the molded article is poor. Even if it is 300 g / 10 minutes or more, there is no particular problem, but the transparency may not be improved so much even when it is made into a composition. The ionizing radiation irradiation treatment can be performed on polyethylene powder or pellets under a vacuum, an inert gas, or an air atmosphere, but it is preferably performed under an inert gas. As the ionizing radiation, X-ray,
Examples thereof include α rays, γ rays, and electron rays, but particularly γ
Rays and electron beams are preferred. The irradiation dose is generally 0.5 to 150 kGy, preferably 1 to 100 k
Gy, especially 2-75 kGy. Irradiation dose is 15
If it exceeds 0 kGy, the MF of the polyethylene resin of (B)
Although it depends on R and density, gelation may occur, causing not only a problem in terms of compatibility, but also making the surface of the molded product uneven, which makes it useless. Therefore, it is necessary to irradiate under conditions that do not cause gelation. The composition ratio of the component (B) in the resin component of the present invention is 1 to 50% by weight, preferably 2 to 45% by weight, and particularly preferably 3 to 40% by weight. If the blending ratio is less than 1% by weight, it will be described below (C).
Even if the components are blended, the synergistic effect of improving the transparency is slight and poor. On the other hand, if it exceeds 50% by weight, not only the effect is saturated but also the mechanical properties are deteriorated, which is not preferable.

Examples of the (C) component (a) nucleating agent include carboxylic acid metal salts, dibenzylidene sorbitol derivatives, and alkali metal salts. Particularly, phosphoric acid alkali metal salts are blended. Is preferred. Specifically, sodium-2,2-methylene-bis (4,6-di-t-butylphenyl) phosphate, sodium-
2,2-Ethylidene-bis (4,6-di-t-butylphenyl) phosphate, sodium-2,2-butylidene-bis (4,6-di-methylphenyl) phosphate, sodium-2,2,- Butylidene-bis (4
6-di-t-butylphenyl) phosphate, sodium-2,2-methylene-bis (4-methyl-6-t-)
Butylphenyl) phosphate, sodium-2,2
-Methylene-bis (4-ethyl-6-t-butylphenyl) phosphate, sodium (4,4-dimethyl-
5,6-di-t-butyl-2,2-biphenyl) phosphate, sodium-2,2-ethylidene-bis-
(4-m-Butyl-6-t-butylphenyl) phosphate, sodium-2,2-methylene-bis (4,6
-Di-methylphenyl) phosphate, sodium-
2,2-methylene-bis- (4,6-di-ethylphenyl) phosphate, potassium-2,2-ethylidene-bis (4,6-di-t-butylphenyl) phosphate, potassium-bis (4,6-di) Examples thereof include -t-butylphenyl) phosphate. These nucleating agents may be used alone or in combination of two or more. Especially sodium-2,2-methylene-bis (4,6-
Di-t-butylphenyl) phosphate, sodium-2,2-ethylidene-bis (4,6-di-t-butylphenyl) phosphate and the like are preferable. The compounding ratio of these nucleating agents is such that the total amount of the components (A) and (B) is 10
It is 0.05 to 0.7 parts by weight, and particularly preferably 0.07 to 0.6 parts by weight, relative to 0 parts by weight. The mixing ratio is 0.
If it is less than 05 parts by weight, the effect of improving transparency is poor. on the other hand,
Even if the amount exceeds 0.7 parts by weight, no further effect can be expected and it is in a saturated state, which is not preferable in terms of cost.

The lithium carbonate (b) in the present invention is a white powder used as a compounding agent for medicines, ceramics, enamel raw materials, heat-resistant glass and the like. The average particle size of the lithium carbonate is usually 50 μm or less, preferably 20 μm or less. The purity of lithium carbonate is not particularly limited, but high purity one should be selected in consideration of the influence of impurities and the like. The blending amount of lithium carbonate is 0.01 to 0.5 part by weight, preferably 0.1 part by weight, based on 100 parts by weight of the total amount of the components (A) and (B).
It is from 03 to 0.45 parts by weight. If the blending amount of lithium carbonate is less than 0.01 part by weight, the transparency is poorly improved. on the other hand,
If it exceeds 0.5 parts by weight, it becomes milky white.

The ethylene-acrylamide resin (c) in the present invention can be obtained by a method of copolymerizing ethylene and an acrylamide compound under high pressure, or a method of graft-polymerizing acrylamide onto a polyethylene resin. These production methods are known to those skilled in the art (for example, JP-B-43-9063, JP-B-44-19537, etc.). As the acrylamide compound, N-alkyl acrylamide, N, N-
Examples thereof include dialkyl acrylamide, N-alkyl methacrylamide and N, N-dialkyl methacrylamide. Specifically, N-ethyl acrylamide,
N-n-propylacrylamide, N-isopropylacrylamide, Nn-butylacrylamide, N-isobutylacrylamide, Nt-butylacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N-ethylmethacrylamide , N
-N-propyl methacrylamide, Nt-butyl methacrylamide, N, N-dimethyl methacrylamide,
N, N-diethylmethacrylamide, N-methyl-N-
Examples thereof include ethyl acrylamide. In the graft reaction, it is preferable to use high-density polyethylene in order to improve the graft ratio. Two or more kinds of these compounds may be mixed. Among the compounds, preferred are N-ethylacrylamide, N-isopropylacrylamide, Nt-butylacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N-methyl-N-ethyl-acrylamide, N-n-propylmethacrylamide, Nt-
Butyl methacrylamide may be mentioned.

Further, when the ethylene-acrylamide resin is produced by the copolymerization method, a third monomer may be contained in addition to ethylene and the acrylamide compound. Examples of the third monomer include unsaturated esters such as vinyl acetate, methyl acrylate and methyl methacrylate, unsaturated carboxylic acids such as acrylic acid, methacrylic acid and maleic acid, and unsaturated vinyl methyl ether, ethyl vinyl ether, butyl vinyl ether and the like. Examples include ether. The content ratio of these third monomers is at most 50 in total with the acrylamide compound.
% By weight, preferably 45% by weight or less. The blending amount of the ethylene-acrylamide resin is 0.1 to 50 parts by weight, preferably 0.15 to 45 parts by weight, and particularly 0.2, based on 100 parts by weight of the total amount of the components (A) and (B). ~ 40 parts by weight. When the blending ratio is less than 0.1 part by weight, the effect of improving transparency is poor. On the other hand, it is not preferable even if it is blended in an amount of more than 50 parts by weight because it is saturated and the physical properties are deteriorated depending on the composition.

The resin composition of the present invention is obtained by mixing the above components using a ribbon blender, a Henschel mixer, and the like, and further melt-kneading them using a kneader, an extruder, a mixing roll, a Banbury mixer, and the like. . Melt flow rate of the resulting resin composition (JIS
According to K7210, measured in Table 1, Condition 4) is usually 0.05 to 100 g / 10 minutes.

[0013]

EXAMPLES The present invention will be described in detail below with reference to examples. In addition, the total light transmittance and haze (cloudiness value) are JIS
It was measured by a haze meter manufactured by Suga Test Instruments Co., Ltd. according to K7105. The appearance was evaluated by visually observing the surface condition of the test piece in the following three stages. ○ ・ ・ ・ ・ No coloring at all. Δ: Some coloring, spots and milky white are seen. × ・ ・ ・ ・ Coloring, spots and milky white are remarkable.

The following was used as the polyethylene resin as the component (A). PE-1: MFR 22 g / 10 min and density 0.9
High density polyethylene PE-2 with 58 g / cm ³ : MFR 19 g / 10 min and density 0.9.
47 g / cm ³ at a high density polyethylene PE-3: MFR is 0.65 g / 10 min and density 0.955 g / cm ³ at a high density polyethylene PE-4: MFR is 6.3 g / 10 min and density 0.
917 g / cm is ³ low-density polyethylene PE-5: MFR there is 3.8 g / 10 min and density 0.
921 g / cm ³ low density polyethylene

The following were used as the polyethylene resin for the component (B). PE-6: MFR 22 g / 10 min, density 0.
High density polyethylene PE-7: MFR of 958 g / cm ³ is 5.2 g / 10 min, high density polyethylene PE-8: MFR of 0.956 g / cm ³ is MFR of 9.2 g / 10 min. And medium density polyethylene PE-9: MFR having a density of 0.935 g / cm ³ of 12 g / 10 min and a density of 0.
Low density polyethylene with 917 g / cm ³

The following nucleating agents were used as the component (C). C-1: sodium-2,2-methylenebis (4,6
-Di-t-butylphenyl) phosphate C-2: sodium-2,2-ethylidene-bis (4
6-Di-t-butylphenyl) phosphate The following was used as the lithium carbonate as the component (C). LC-1: average particle size of 16 μm and purity of 99.1% LC-2: average particle size of 7 μm and purity of 99.1%

The following were used as the ethylene-acrylamide resin as the component (C). DMA-1: ethylene-N, N-dimethylacrylamide copolymer (N, N-dimethylacrylamide content;
18.3 wt%, MFR; 3.5 g / 10 min) DMA-2: ethylene-N, N-dimethylacrylamide copolymer (N, N-dimethylacrylamide content;
37% by weight, MFR; 4.2 g / 10 minutes) DMA-3: ethylene-acrylamide copolymer (acrylamide content; 11.4% by weight, MFR; 4.6 g
/ 10 minutes) g-DMA-1: N, N-dimethylacrylamide grafted high density polyethylene (raw material polyethylene; MFR
8.1 g / 10 min, density 0.954 g / cm ³ , N,
N-dimethylacrylamide 11.2% by weight, MFR
1.2 g / 10 minutes) g-DMA-2: N, N-diethylacrylamide grafted high density polyethylene (raw material polyethylene; MFR
7.6 g / 10 minutes, density 0.946 g / cm ³ , N,
N-diethylacrylamide 10.6% by weight, MFR
0.8 g / 10 minutes) g-DMA-3: N, N-dimethylacrylamide graft linear low-density polyethylene (raw material polyethylene; M
FR 12 g / 10 minutes, density 0.917 g / cm ³ ,
N, N-dimethylacrylamide 4.3 wt%, MF
R 0.8 g / 10 minutes) g-DMA-4: N, N-dimethylacrylamide graft medium density polyethylene (raw material polyethylene; MFR
9.2 g / 10 minutes, density 0.935 g / cm ³ , N,
N-dimethylacrylamide 5.7% by weight, MFR
1.1 g / 10 minutes) The acrylamide content was measured by an infrared spectrophotometer and
It measured using < ¹³ > C-NMR.

Production Examples of Component (B) (XPE-1 to 5) As the component (B), polyethylene shown in the following Table 1 is γ.
The irradiation dose shown in Table 1 was irradiated under a nitrogen atmosphere using a beam irradiation device (manufactured by Koga Isotope Co., Ltd.) or an electron beam irradiation device (manufactured by Nisshin High Voltage Co., Ltd.). Then, MFR was measured and the results are shown in Table 1.

[0019]

[Table 1]

Examples 1 to 22 and Comparative Examples 1 to 10 After mixing the components shown in Tables 2 and 3 in the types and blending amounts of the respective components using a tumbler, an extruder with a coaxial biaxial vent (Kobe Steel Works Ltd. Manufactured by KTX-37). Using the injection molding machine (manufactured by Toshiba Machine Co., Ltd., IS-170II-5A type), test pieces (size 10 × 12 cm, thickness 1.0 mm) were produced from the obtained pellets. The optical properties (total light transmittance and haze) and the appearance of each test piece were measured. The results are shown in Tables 2 and 3.

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

The resin composition of the present invention has excellent transparency,
Moreover, since it has good moldability and appearance, it is useful as various packaging materials, industrial materials, and medical materials.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area C08L 33:26)

Claims (3)

[Claims] 1. (A) Polyethylene resin 50-99
(C) From the following (a), (b) and (c) to 100 parts by weight of a resin component consisting of 1 to 50% by weight of a resin-treated product obtained by subjecting a polyethylene resin to ionizing radiation irradiation (B). A polyethylene resin composition containing at least one selected. (A) Nucleating agent: 0.05 to 0.7 parts by weight (b) Lithium carbonate: 0.01 to 0.5 parts by weight (c) Ethylene-acrylamide resin: 0.1 to 50 parts by weight 2. The polyethylene resin composition according to claim 1, wherein the nucleating agent is an alkali metal salt of phosphoric acid. 3. The polyethylene resin composition according to claim 1, wherein the ethylene-acrylamide resin is an ethylene-acrylamide resin containing 0.01 to 50% by weight of an acrylamide compound unit and an ethylene unit.