JPS58171424A - Ethylene-alpha-olefin copolymer composition for molding blown film by water cooling - Google Patents

Abstract

PURPOSE:A copolymer composition useful for molding a blown film by water cooling, having improved blocking resistance and transparency, obtained by adding a specific high-density polyethylene to an ethylene.alpha-olefin copolymer. CONSTITUTION:A composition comprising (A) 60-95wt% copolymer and ethylene and 4-20C alpha-olefin having 0.5-3(g/10min) melt flow rate MFR2 by 2,160g weight, 0.910-9.940(g/cm<3>) density, 40-70% crystallinity by X-ray, and 115- 130 deg.C melting point and (B) 5-30wt% high-density polyethylene having 0.1- 32MFR2 by 2,160g weight, a ratio of MFR10 by 10kg weight to MFR2 of 5- 18MFR10/MFR2 and 0.945-0.970 density.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention c) Ethylene α, which is suitable for water-cooled blown film molding, has excellent blocking resistance, and has transparency.
-Relating to an olefin copolymer composition.

A copolymer of ethylene and α-olefin, called linear low-density polyethylene (L-I, DPI), has a higher mechanical strength (tensile strength) than conventional high-pressure low-density polyethylene (HPPE). It has excellent strength, tear strength, impact strength, etc.), heat resistance, stress crack resistance, optical properties, and heat sealability, and is suitable as a material for blown films.

On the other hand, as means for improving the transparency of blown films, two-stage cooling methods using air cooling, water cooling methods, etc. are known. However, in general, when the transparency of a film is improved by the above-mentioned molding method, the blocking resistance tends to decrease, and particularly in the case of blown film molding, there is a risk that the film after molding may become dry in the sun. Therefore, in general, metal soaps such as calcium stearate and zinc stearate, fatty acids such as stearic acid and palmitic acid, acid amides such as stearylamide, oleylamide, and palmitylamide, oleic acid monoglyceride, butyl stearate, and smearic acid monoglyceride are used. Various lubricants such as fatty acid esters, other higher alcohols, liquid paraffin, wax, and silicone, and inorganic substances such as silica are added to prevent blocking. However, conventional additives mainly exert their anti-blocking effect by oozing out onto the resin surface, so if they are used in large quantities, they tend to contaminate the packaged object, make the film surface cloudy, and reduce transparency. Ta.

The present inventors investigated the prevention of blocking in ethylene/α-olefin copolymer films and found that by adding a specific high-density polyethylene, it was possible to prevent blocking without impairing transparency. It was found that there was no leakage of the agent, and the present invention was achieved.

That is, the present invention melts at a load of 216'Og.

-Rate string FR2 is 0.5 to 3 g710 min
, density is 0.91.0 or L94067an3,
xMniJ: ;6 Copolymer (A) of ethylene and α-olefin having 4 to 20 carbon atoms having a crystallinity of 40 to 70% and a melting point of 115 to 130'C: 60 to 95% by weight , melt flow rate at a load of 2160 g) MFR2 is 0.1 to 32 g 710 m 'r
Melt flow rate MFR1 at n% load 10 to 9
The ratio MFR between o and the MFR2, o/MFR2 is 5 to 18 and the density is 0.945 to 0.970 g/l
- High density polyethylene (B): 5 to 40% by weight, with excellent blocking resistance, characterized by comprising:
The present invention also provides an ethylene/α-olefin copolymer composition for forming a water-cooled blown film that has transparency.

Ethylene/α-olefin copolymer used in the present invention (in Shu, carbon number 4 to 20 copolymerized with ethylene)
Examples of α-olefins include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-
Octene, 1-decene, 1-tetradecene, 1-octadecene, or a mixture of at least two thereof can be mentioned. Among these, copolymers using α-olefins having 6 to 18 carbon atoms have particularly high impact resistance and
It is preferable because it has excellent tear resistance and the like.

The MFR2 of the ethylene/α-olefin copolymer (A) is in the range of 0.5 to 3 g/10 m1n.

If the MFR2 is less than 0-5 g710mln, the melt viscosity is high and the moldability is poor, and the MFR2 is less than 3.0g7'1
If it exceeds 0 m1n, the melt tension is so small that it is impossible to form a water-cooled blown film. Note that MFR2 in the present invention is a value measured by the method of ASTM Di21;H;.

The density of the ethylene/α-olefin copolymer (A) is 0
．． There are also notes in the range of 910 to 0.94 og/cM3.

If the density is less than 0.910 g/an3, the film will be too soft and sticky, and the blocking resistance will not be improved even if high-density polyethylene ω) described below is added.

If it exceeds 0.940 gA-, the rigidity will be large and the transparency will also be reduced, which is not preferable. Note that the density in the present invention is a value measured by the method of ASTM D 1505. The X-ray crystallinity of the ethylene/α-olefin copolymer (A) is correlated with the density, but is 40 to 70%.
, particularly preferably in the range of 45 to 60%. When the crystallinity exceeds 70%, the transparency decreases, and the crystallinity increases by 40%.
Anything less than that has poor mechanical strength.

The melting point of the ethylene/α-olefin copolymer (A) is defined as the temperature increase rate of 10°C/10°C on a differential scanning calorimeter (DSO).
It is the highest temperature among one or more, often two to six, sharp endothermic peaks found from an endothermic curve where m>n. The copolymer (A) preferably has a melting point in the range of 115°C to 130°C, particularly 115°C to 125°C. Those with a melting point of less than 115°C have poor heat resistance, and those with a melting point of more than 130°C have poor transparency and low-temperature heat sealability.

Ethylene/α-olefin copolymer (A
) is a copolymer with the above-mentioned properties, a blown film with excellent mechanical properties such as impact resistance and tear resistance can be obtained. Below, those with a molecular weight of 4 or less are particularly preferable because a blown film with even better transparency can be obtained. The molecular weight distribution is determined by determining the molecular weight distribution curve using gempermeation chromatography.
This is a value obtained by calculating the weight average molecular weight and number average molecular weight by the universal calibration method using polystyrene as a standard.

The copolymer with the above properties used in the present invention (Kiku is a transition metal catalyst, for example, a highly active titanium catalyst component formed from a magnesium compound and a titanium compound, and a catalyst consisting of an organoaluminium compound, and an α-olefin at a ratio that gives the required density.In order to obtain the desired melt flow rate, a molecular weight regulator such as hydrogen may be used.The polymerization is carried out by slurry polymerization. The polymerization can be carried out by various methods such as , gas phase polymerization, and high-temperature solution polymerization.

In the present invention, the ethylene/α-olefin copolymer (high-density polyethylene (9) to be mixed with chrysanthemum) is MFR
2 is 0.1 to 32g/iomin, preferably L, <
Hao, s or 20g/I'lI+3, MFR1o/
M, FR2 is in the range of 5 to 18, preferably 7 to 15 and the density is in the range of 0.945 to 0.970 g,/an'. If the MFR2 is less than 0.1 g/10 m1n, when the composition is made into a film, fish eyes will occur in the film and the moldability will be poor. MFR2
If it exceeds 32 g/10 m1n, the moldability is poor and the impact resistance of the composition is reduced. Mv R+ 0 /M
If p R2 is less than 5, the moldability of the composition decreases,
If it exceeds 18, the transparency of the film decreases. If the density is less than 0.945 g//cIII3, there is no anti-blocking effect.

The ethylene/α-olefin copolymer composition (hereinafter sometimes abbreviated as “composition”) for forming a water-cooled blown film of the present invention comprises the ethylene/α-olefin copolymer (gradient) and high-density polyethylene (B). 9515 to 60/40 (wt%), preferably 90/10 to 7
It is a mixture of 0/30 (weight%). If the amount of high-density polyethylene CB) added is less than 5% by weight, there will be no blocking prevention effect, and if it exceeds 40% by weight, transparency will decrease, and low-temperature heat sealing, which is a characteristic of ethylene/a-olefin copolymer, will occur. There is a risk that heat sealing performance such as adhesive properties and hot tack properties may be impaired.

To obtain the ethylene/α-olefin copolymer composition, the ethylene/α-olefin copolymer (A) and high-density polyethylene (B) are mixed in the following ranges using various known methods,
For example, mixing with a V-blender, tumbler blender, Henschel mixer, ribbon blender, etc., kneading and granulating with a single-screw extruder, multi-screw extruder, etc. after mixing, or melt-kneading with a kneader, Banbury mixer, etc. A method of post-granulation can be adopted.

The composition of the present invention may contain conventional additives such as weathering stabilizers, heat stabilizers, antistatic agents, antifogging agents, pigments, dyes, nucleating agents, rust preventives, antiblocking agents, and small amounts of lubricants and antiblocking agents. Various compounding agents used in addition to the polyolefin may be blended within a range that does not impair the purpose of the present invention. In addition, high-pressure low-density polyethylene, ethylene/vinyl acetate copolymer, non-quality or low crystallinity ethylene/propylene or ethylene/1.
-Butene copolymers and the like may be added.

Since the composition of the present invention has excellent blocking resistance, it is suitable for a method of imparting transparency by a rapid cooling method such as water-cooled blown film forming.

The blown film made from the composition of the present invention has excellent anti-blocking properties, so it has good opening properties and no oozing of the anti-blocking agent, and also has excellent transparency and impact strength, which are characteristics of the ethylene/α-olefin copolymer (A). , tear strength, and heat sealing performance, it is suitable as a single film for various packaging films such as rice snacks, agricultural foods, livestock foods, seafood foods, and textile packaging.
Furthermore, the above-mentioned packaging film can be made into a multilayer film with two or three or more layers using the composition as the inner layer and polypropylene, high-density polyethylene, nylon, polyester, cellophane, ethylene/vinyl alcohol copolymer, polyvinylidene chloride, etc. as the outer layer. Can be used.

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 MPR2: 2-5g/10 m'n% density:
0.953 g/a3, crystallinity by X-ray: 57.
Ethylene 4-methyl-9%, melting point 125°C (with peaks at 122°C and 114°C) and molecular weight distribution: 2.8
1-pentene copolymer (hereinafter abbreviated as E'M P-1) 8
0% by weight, MP'R2: 13.0g/l 0mln,
MFR10/MFR2: 9.6 and density 0.965
gAI++5 high-density polyethylene (hereinafter referred to as HDP'E-
1) and 1% by weight of a masterbatch with a concentration of 10% by weight of silica as an anti-blocking agent were mixed in a Henschel mixer and then mixed in a 40mmφ extruder (set temperature:
The film was extruded from a 100 mmφ circular die (die lip: 0.8 mm, temperature set at 210° C.) to obtain a blown film with a fold width of 160 mm and a thickness of 40 μm. Next, the performance of the film was evaluated by the following method.

Seismic intensity (%): ASTM D 1003 gloss (%)
: ASTM'D 523 Film appearance (visual inspection) Check appearance defects due to frequent occurrence of Nigel and poor compatibility,
Good was rated as 0, and poor was rated as ×.

Blocking (BII: g715mm): ASTM D
893 Impact strength (Fx: kg-an/cytt): AST
MD 3420 results are shown in Table 1.

Examples 2 to 4 MFR2 instead of HDpg-1 used in Example 1:
s, sg/10mi10m1nX. /MFR2: 9.
4 and high-density polyethylene with a density of 0.96867 cm5 (hereinafter abbreviated as HDPIc-1), MFR2: 1.1
g/l 0mtn.

MFRl. /MAR2: 9.3 and density 0.954
High-density polyethylene (hereinafter abbreviated as HDPK-1) of g Shio 3 and MIPR2' 0.9 g / 10 min
Example 1 except that 4 each of high-density polyethylene (hereinafter abbreviated as HDpK-ff) with a density of 0.9 s 4 g/as' and a density of 0.9 s 4 g/as' were used.
I did the same thing. The results are shown in Table 1.

Comparative Examples 1 to 4 MFR2' instead of HDPK-1 used in Example 1
O-4g710 min % M F R1o/M
F R2” 19-0 and density 0.958 g/(- high density polyethylene (hereinafter abbreviated as HD, PIC-V),
MFR2: 0.04g/10mln.

MFR10/MFR2: 28-0 and density o
, 956g/CrR3 high density polyethylene (HD
(abbreviated as PIC-W), Mel F flowray) -8.5g/
1010m1n (AST 1238, L) polypropylene (product name Mikata Petrochemical Polypro@11'63[]
, manufactured by Sansampata Petrochemical Industry K (hereinafter abbreviated as pp) and MF
R2: 3.3g/10m1n high-pressure low-density polyethylene (trade name: Mirason NEO-25H.

The same procedure as in Example 1 was carried out except that LDPK (manufactured by Mikata Polychemical KK, hereinafter abbreviated as LDPK) was used. The results are shown in Table 1.

Reference Example 1.2 IMF-1 used in Example 1 and Comparative Example 3 instead of the composition of ICMP-1 and HDPK-1 used in Example 1
Table 1 shows the results obtained in the same manner as in Example 1 except that each of the PPs used in Example 1 was used alone. However, in EMP-1, silica masterbatch, which is an anti-blocking agent, was not added.

Example 5 The same procedure as in Example 1 was conducted without adding the silica masterbatch as an anti-blocking agent to the composition of mMp-1 and HDPK-1 used in Example 1. The results are shown in Table 1.

Comparative example 5

Claims (1)

[Claims] (1) Melt flow rate MF at a load of 2160g
R2 is 0.5 to 3g/10m1n, density is 0.91
Copolymer of ethylene and a-olefin having 4 to 20 carbon atoms (~:60 -95% by weight and load 2160g
Melt flow rate MPR2 is 0.1 to 32g
/10m1n, melt flow rate M at load 10A9
The ratio MFR between F R1o and the MFR2. /M
P H2 is 5 to 18 and density is 0.945 to 0
．． 9706/C- high density polyethylene (B): 5 to 40% by weight. An ethylene/a-olefin copolymer composition for forming a water-cooled blown film.