JPS58120654A - Ethylene-alpha-olefin copolymer composition - Google Patents

Abstract

PURPOSE:A composition having improved hot tack tear strength, transparency, impact strength resistance, etc., obtained by adding an ethlylene vinyl acetate copolymer with high content of vinyl acetate to a specific ethylene alpha-olefin copolymer. CONSTITUTION:(A) 95-60pts.wt. copolymer of ethylene and 4-20C alpha-olefin, having 0.1-20g/10min melt flow rate, 0.91-0.94g/cm<3> density, and 115-130 deg.C melting point is blended with (B) 5-40pts.wt. ehtylene-vinyl acetate copolymer 0.1-50g/10min flow rate, 0.92-0.98g/cm<3> density, 40-100 deg.C melting point and 10-50wt% vinyl acetate content. Preferably the amount of the component A blended is 90-70pts.wt. and that of the component B is 10-30pts.wt. >=6C alpha-olefin is preferable as the alpha-olefin of the component A. USE:Useful as a packaging film, and a packaging bag in the field of packed frozen food, for moist food, paste food, and oily food.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ethylene/α-olefin copolymer composition having excellent hot tack properties.

Low-melting point polyethylene resins such as ethylene/vinyl acetate copolymer and high-pressure low-density polyethylene have low-temperature sealing properties,
Because of its transparency, it is used in large quantities as a sealing material for films. However, such resins have poor hot tack properties (resistance when peeling force is applied to the sealed portion immediately after heat sealing or during temperature), so when used for automatic filling packaging, packaging speed and appropriate temperature must be controlled. It was necessary to pay sufficient attention to this. On the other hand, ionomers are known as one of the resins with excellent hot tack properties, but although such films have excellent hot tack properties, they have drawbacks such as poor tear strength and hygroscopicity, which may cause foaming during molding. was there. In view of the current situation, the present inventors investigated the development of a resin with excellent hot tack properties to replace ionomers, and found that a specific ethylene-α
-A composition made by adding an ethylene/vinyl acetate copolymer with a high vinyl acetate content to an olefin copolymer has excellent hot tack properties, as well as tear strength, transparency, impact strength, mechanical strength, and moldability. It was found that the present invention is excellent.

That is, the present invention has a melt flow rate of 0.1 to 20.
g/10mtn, density 0.910 to 0.940g/
Copolymer (A) of ethylene and α-olefin having 4 to 20 carbon atoms and having aI3 and a melting point of 115 to 130°C
:95 to 60 parts by weight and melt flow rate 0.1
to 50 g/10 min% density 0.92
0 to 0.980g/33, melting point 100 to 40°
Ethylene/vinyl acetate copolymer (B) with C and vinyl acetate content of 10 to 50% by weight: 5 to 40 parts by weight (
However, A) 100% = I 00 parts by weight. ) to provide an ethylene/α-olefin copolymer composition comprising:

The ethylene-α-olefin copolymer used in the composition of the present invention has a melt flow rate (ASTMD123B:
E) is 0.1 to 20 g/10 min s
Preferably 0.5 to 5 g710 min % density 0.910 to 0.940 g/(7)3, preferably 0.915 to 0.935 g/(7)3 and melting point 1
15 to 130°C1 preferably 118 to 125
It is a copolymer of ethylene and an α-olefin having 4 to 20 carbon atoms, preferably 6 to 18 carbon atoms.

If the melt flow rate is less than 0-1 g/l 0mtn, the melt viscosity is high and the moldability is poor, and the melt flow rate is less than 20 g/10 mtn.
Those exceeding m1n have low melt viscosity, poor moldability, and low mechanical strength. Density is 0.910g/crIt3
If the value is less than 0.940g/c7N5, the surface will be sticky when made into a film, and the oil resistance and heat resistance will be poor. sex is not improved. melting point is 1
If the temperature is less than 15°C, the heat resistance is poor, and if the temperature exceeds 130°C, the hot tack property will not be improved even if the ethylene/vinyl acetate copolymer (B) is added. The melting point in the present invention refers to the highest temperature at a point showing an endothermic peak determined from an endothermic curve measured by a differential scanning calorimeter (DSO) at a heating rate of 10°C/min. The ethylene/α-olefin copolymer (A) used in the present invention has one or more endothermic peaks, often two or three. Specifically, the α-olefin having 4 to 20 carbon atoms to be copolymerized with ethylene includes 1-butene, 1-pentene, 1-
hexene, 4-methyl-1-pentene, 1-octene,
1-decene, 1-tetradecene, 1-octadecene or a mixture thereof. Those copolymerized with propylene are not preferred because they have poor mechanical strength and heat seal strength. In particular, copolymers with α-olefins having 6 or more carbon atoms are preferred because they have excellent impact resistance.

Further, if the ethylene/α-olefin copolymer (A) in the above range used in the present invention is one with a molecular weight distribution (weight average molecular weight/number average molecular weight) of 6 or less, a film with even better transparency can be obtained. This is preferable because it allows The molecular weight distribution values were determined using gel permeation chromatography (
This is a value obtained by obtaining a molecular weight distribution curve by the apc) method and calculating the weight average molecular weight and number average molecular weight.

Ethylene/α-olefin copolymer (A
) The ethylene/vinyl acetate copolymer (B) to be added to the melt 70-rate (ASTMD 125B:E)
is 0.1 to 50 g/10 min s, preferably 0.5 to 30 g710 min, and the density is 0.920
to 0.980 g/α3, preferably 0.930 to 0.960 g/ax', melting point 100 to 40°
C1 preferably at 95 to 55°C and with a vinyl acetate content in the range of 10 to 50% by weight, preferably 10 to 35% by weight. Melt flow rate is O-1
g/ less than 10 min, the moldability is poor < , 5
If it exceeds 0 g/10 m1n, mechanical strength will be low and hot linkability will not be improved. Density is 0.92
If it is less than 0 g/ff13, the effect of improving hot tack properties is poor, and if it is more than 0.980 g/(7)3, there is a problem in moldability. Those with a melting point of less than 40'C are
It has poor heat resistance and oil resistance, and hot tack properties cannot be improved if the temperature exceeds 100°C. Vinyl acetate content is 10
If it is less than 5% by weight, the effect of improving hot tack properties is small;
If it exceeds 0% by weight, the mechanical strength is low.

The composition of the present invention contains the ethylene/α-olefin copolymer (A) and the ethylene/vinyl acetate copolymer (B) at 9%
515 to 60/40 (parts by weight), preferably 90/
It is a mixture in a range of 10 to 70/30 (parts by weight). If the amount of the ethylene/vinyl acetate copolymer (B) is less than 5 parts by weight, the hot tack properties will not be improved, and if it exceeds 40 parts by weight, the mechanical strength will be significantly reduced.

In order to obtain the ethylene/a-olefin copolymer composition of the present invention, the ethylene/α-olefin copolymer (A) and the ethylene/vinyl acetate copolymer (g)) are mixed in various known manners within the above-mentioned ranges. Examples of methods include mixing with a V-blender, ribbon Bremburg Henschel mixer, tumbler blender, etc., granulating with an extruder after mixing, or kneading and granulating with an extruder, Banbury mixer, etc. can be taken.

The ethylene/a-olefin copolymer composition of the present invention itself as a film has excellent hot tack properties, tear strength, transparency, low temperature heat sealability, impact strength,
Since it has an appropriate film stiffness, it can be used alone as a packaging film, agricultural film, or protective film, but it is suitable for various heavy speeds by taking advantage of its hot tack properties and laminating it with various base materials. A packaging film is obtained.

As these base materials, any polymer having film-forming ability, paper, aluminum foil, cellulose, etc. can be used. Examples of polymers include high-density polyethylene, medium- and low-density polyethylene, and ethylene.
Vinyl acetate copolymer, ethylene/acrylic acid ester copolymer, ionomer, polypropylene, poly-1-butene, olefin polymers such as BoIJ-4-methyl-1-pentene, polyvinyl chloride, polyvinylidene chloride, polystyrene , polyacrylate) vinyl polymers such as polyacrylonitrile, nylon 6S, nylon 66, nylon 7, nylon 10, nylon 11, nylon 12,
Examples include polyamides such as nylon 610 and polymethaxylylene adipamide, polyesters such as polyethylene terephthalate, polyethylene terephthalate/isophthalate, and polybutylene terephthalate, polyvinyl alcohol, ethylene/vinyl alcohol copolymers, and polycarbonates. These base materials can be appropriately selected depending on the purpose and the item to be packaged. For example, if the packaged item is a food that is easily corroded, use materials such as polyamide, polyvinylidene chloride 1 ethylene/vinyl alcohol:l A/copolymer, polyvinyl alcohol 1 polyester, which have excellent transparency, rigidity, and gas permeation resistance. resin is selected. For confectionery, textile packaging, etc., polypropylene or the like having good transparency, rigidity, and moisture permeation resistance can be selected as the outer layer. Further, if the base material is a polymer, it may be uniaxially or biaxially stretched.

Methods for producing a composite film in which a film made of the ethylene/a-olefin copolymer composition of the present invention and the base material are laminated include a dry lamination method, an extrusion lamination method, a sandwich lamination method, a coextrusion method, etc. Various known methods can be employed.

In addition, the ethylene/α-olefin copolymer composition of the present invention includes a weathering stabilizer, a heat stabilizer, an antistatic agent, an antifogging agent,
Various additives such as anti-blocking agents, slip agents, lubricants, pigments, dyes, droplet agents, etc. which are usually added to polyolefins may be added to the extent that the purpose of the present invention is not impaired.

The ethylene/α-olefin copolymer composition of the present invention can be used as a packaging film for packaging various items, but it has excellent hot tack properties, low temperature heat seal properties, tear resistance, and transparency. For example, in the frozen food packaging field, packaging bags for watery foods such as pickles, tofu, konnyaku, etc., packaging bags for oil-based foods such as curry, yakiniku sauce, soup 1 butter, cheese, etc., packaging bags for pasty items such as miso, jam, etc. It can be suitably used for etc.

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples in any way unless the gist of the invention is exceeded.

Example 1 Melt flow rate' 2-5 g/10 min
s density: 0=915, melting point: 124°C (119°0,
There is a peak at 101°C) and molecular weight distribution: 3.6 ethylene/4-methyl-1-pentene copolymer C or lower E
(abbreviated as Ili P-work) Nia 0 parts by weight and Melt 70-
Rate: 2. Og/IQmin, density: 0.95
0 g/cM3, melting point near 8°C and vinyl acetate content: 255 weight of ethylene! Vinyl acetate copolymer (Evaflex P-2505 manufactured by Mitsui Polychemil Co., Ltd.: hereinafter K
VA-1) was mixed with 250 parts by weight in a tumbler blender, melted in an extruder with a diameter of 5°C (temperature set at 180°C), and then put into a circular die with a diameter of iomm diameter (die lip: 1.2mm, set). After extruding the bubble at a temperature of 170° C. and cooling it in air, a blown film with a finger width of 230 mm and a thickness of 30 μm was obtained. Next, physical properties were evaluated by the following method.

Haze (%): ASTM D 1003 Gloss (%):
ASTM D2457 Incident angle: 20 degrees Impact strength (kt
i-Cm10ft): ASTM D 3420 Tear Strength (kg/l): , TIS Z 1702 Bending Stiffness (kQ10112): 140 x 140m
m(7) test piece was prepared, and Han41e-0-Mete
r (manufactured by Thwing Albert, USA), apply bending stress to the test piece with a slit width of 5 mm, calculate the maximum stress, and calculate the bending stiffness (kg/C) by dividing the value by the thickness of the test piece.
IIJ2). The bending rigidity was determined at two points in the longitudinal and lateral directions of the sample.

Peel strength of heat-sealed part (g/15mm): Overlapping film surfaces, 100°C, 105°C, 110°C1
The sample was sealed at 120°C, 1130°C, 140°C, and 150°C for 1 second using a seal bar with a width of 5 mm and a pressure of 2 kg/an2, and then allowed to cool. A 15 mm wide test piece was cut from these and the crosshead speed was 200 mm/mi.
The heat-sealed portion was peeled off at n, and the strength at that time was defined as the peel strength.

Hot tack test (mm): length 550mm x width 20m
Layer m test pieces at 105°C and 110°C at 1120°C.
°C, 130°C, 140°C, 150'C temperature, width 5
mm, with a seal bar of length 300 mm, 2 kg/
After sealing at art 2 pressure for 1 second, the sealed portion was forcibly peeled off by applying a load of 43 g to each test piece at the same time as the pressure was removed, and the hot tack property was evaluated based on the peeling distance (mm). That is, the shorter the peeling distance, the better the hot tack properties.

The results are shown in Table 1.

Example 2.3 Example 1 (7) KMP-I/EVA-I = 70
The same procedure as in Example 1 was carried out except that the mixing ratio of 1/50 was changed to 77/25 and 90/10 (parts by weight). The results are shown in Table 1.

Example 4 Instead of Evi-1 used in Example 1, melt flow rate: 2.5 g/l 0 min % density: o,
+; +4 g/cW13, melting point: 85°C, vinyl acetate content: 19% by weight ethylene/vinyl acetate copolymer (Evaflex P-1905 manufactured by Mitsui Polychemical Co., Ltd. 2 hereinafter abbreviated as IVA-1) was used. was carried out in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1 Instead of the EVA coating used in Example 1, Melt 70-
): 1.7 g/10 min, density: 0
．． Using an ethylene/vinyl acetate copolymer (EVAFLEX P-0803 manufactured by Mitsui Polychemical Co., Ltd., hereinafter abbreviated as EVA-1) with a melting point of 98°C and a vinyl acetate content of 8% by weight, the mixing ratio was 93g/cIJI3. The same procedure as in Example 1 was carried out except that the ratio was changed to 80/20. The results are shown in Table 1.

Comparative Example 2 The same procedure as in Example 1 was carried out except that the mixing ratio of EMP-E/EVA-1=70/30 was 50,150 (parts by weight). The results are shown in Table 1.

Example 5 Melt 7 was used instead of EMP-■ used in Example 1.
0-Le): 2.5 g/10 min, density: fl, 923 g/G3, melting point = 126°C (119°
C, there is also a peak at 104°C) and molecular weight distribution: 3.6
The same procedure as in Example 1 was conducted except that the ethylene-4-methyl-1-pentene copolymer (hereinafter abbreviated as EMP-1) was used. The results are shown in Table 1.

Comparative Example 6.4 EMP-■ used in Example 1 and EM used in Example 5
Example 1 except that P-1 was made into a film alone.
I did the same thing. The results are not shown in Table 10 Lazy Example Same as Example 1 except that an ionomer (Himilan ■ 1650, manufactured by Mitsui Polychemical Co., Ltd.; hereinafter abbreviated as 1M) was used instead of the composition used in Example 1. went. The results are shown in Table 1.

Claims (1)

[Claims] (1) Melt flow rate 0.1 to 20 g/
10 min s density 0.910' to 0.940
Copolymer of ethylene and α-olefin having 4 to 20 carbon atoms (g/♂ and melting point of 115°C to 10°C)
A): 95 to 60 parts by weight, melt flow rate 0.1 to 50g/l 0mln
. Density 0.920 to O-980g/ax3, melting point 10
Ethylene-vinyl acetate copolymer (B) with a temperature of 0°C to 40°C and a vinyl acetate content of 10% to 50% by weight
: 5 to 40 parts by weight of an ethylene/α-olefin copolymer composition.