JPS6228172B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an ethylene-α film for film forming that has excellent blocking resistance, heat resistance, and transparency.
- Regarding an olefin copolymer composition. A copolymer of ethylene and α-olefin called linear low-density polyethylene (L-LDPE) is different from conventional high-pressure low-density polyethylene (HPPE).
It has excellent mechanical strength (tensile strength, tear strength, impact strength, etc.), heat resistance, stress crack resistance, optical properties, and heat sealability as a film, and is suitable for various packaging materials, agricultural materials, etc. It is suitable as a base film. As a means for improving the transparency of a film, there are known methods of rapidly cooling a blown film using a two-stage air cooling method, a water cooling method, a T-die molding method, or the like. However, generally L-
LDPE films are prone to blocking, and when the transparency is improved by the above-mentioned molding method, the blocking resistance tends to drop markedly.Especially in inflation film molding,
There was a risk that the film would become unopenable after molding. On the other hand, when thermoplastic resins such as polyolefins, including L-LDPE, are molded at high temperatures of 200 to 300°C, a heat stabilizer is always used in combination. Tetrakis [methylene-3-(3,5-di-
Although t-butyl-4-hydroxy-phenyl)propionate]methane is known, it has surprisingly been found that when this heat stabilizer is used in combination, the blocking resistance is significantly reduced. Therefore, the present inventor has developed a method that has heat resistance, blocking resistance,
As a result of studies aimed at obtaining an ethylene/α-olefin copolymer for film molding with excellent transparency, the present invention was achieved. That is, the present invention has a melt flow rate (MFR) of 0.5 to 20g/10min and a density of 0.915.
to 0.940 g/cm ³ , a copolymer of ethylene and α-olefin having 4 to 20 carbon atoms () having a crystallinity of 40 to 65% by X-rays and a melting point of 115 to 130°C: per 100 parts by weight (A) n-octadecyl-3-(4'-hydroxy-
(3', 5'-di-t-butylphenol) propionate: 0.01 to 1 part by weight, (B) Silica: 0.01 to 0.5 part by weight, and optionally further (C) Vitamin E: 0.01 to 0.2 part by weight, or (D) 2,6-di-t-butyl-p-cresol:
The object of the present invention is to provide an ethylene/α-olefin copolymer composition for film molding, which is characterized by containing 0.01 to 0.5 parts by weight of the copolymer and has excellent blocking resistance, heat resistance, and transparency. In the ethylene/α-olefin copolymer () used in the present invention, examples of α-olefins having 4 to 20 carbon atoms copolymerized with ethylene include:
1-butene, 1-pentene, 1-hexene, 4-
Examples include methyl-1-pentene, 1-octene, 1-decene, 1-tetradecene, 1-octadecene, or a mixture of at least two thereof. Ethylene/α-olefin copolymer ()
The MFR is in the range of 0.5 to 20 g/10 min, preferably 0.7 to 10 g/10 min. MFR
If it is less than 0.5 g/10 min, the melt viscosity is high and the moldability is poor, and if it is more than 20 g/10 min, the melt viscosity and melt tension are low and film molding is impossible. The MFR in this invention is ASTM D
1238, the value measured by the method of E. The density of the ethylene/α-olefin copolymer () is 0.915 to 0.940 g/cm ³ , preferably 0.925
and 0.935 g/cm ³ . Density is 0.915
If it is less than g/cm ³ , the film will be too soft and sticky, and the blocking resistance will not be improved even if the additives described below are added. If the weight exceeds 0.940 g/cm ³ , the rigidity becomes large and the transparency decreases, which is not preferable. In addition, the density in this invention is ASTM D
This is the value measured using the 1505 method. Ethylene α-
The X-ray crystallinity of the olefin copolymer () is correlated with the density, but it is 40 to 65%, especially 45%.
It is preferably in the range of 60% to 60%. If the degree of crystallinity exceeds 65%, transparency will decrease, if it is less than 40%, mechanical strength will be poor, and blocking resistance will not be improved even if the additives described below are added. The melting point of the ethylene/α-olefin copolymer () is one or more, in most cases two or three, determined from the endothermic curve of a differential scanning calorimeter (DSC) at a heating rate of 10°C/min. This is the highest temperature among the sharp endothermic peaks that exist. And copolymer (A) has a melting point of 115℃ to 130℃, especially 115℃
The temperature range is preferably from 125°C to 125°C. Melting point is 115
Those below 130°C have poor heat resistance, and those above 130°C have poor transparency and low-temperature heat sealability. If the ethylene/α-olefin copolymer () used in the present invention is a copolymer with the above properties, a blown film with excellent mechanical properties such as impact resistance and tear resistance can be obtained. Those having a molecular weight distribution (weight average molecular weight/number average molecular weight) of preferably 6 or less, particularly preferably 4 or less, are preferable because a blown film with further excellent transparency can be obtained. The molecular weight distribution is a value obtained by obtaining a molecular weight distribution curve using a gel permeation chromatograph, and calculating the weight average molecular weight and number average molecular weight by the universal calibration method using polystyrene as a standard. The copolymer (A) having the above properties used in the present invention is produced by using a transition metal catalyst, for example, a catalyst consisting of a highly active titanium catalyst component formed from a magnesium compound and a titanium compound, and an organoaluminium compound, using a so-called medium and low pressure method. Therefore, it can be obtained by polymerizing ethylene and α-olefin in a ratio that provides the required density. In order to obtain the desired melt flow rate, a molecular weight regulator such as hydrogen may be used. Polymerization is slurry polymerization, gas phase polymerization,
It can be carried out by various methods such as high temperature solution polymerization. The composition of the present invention has ethylene α-
(A) n-octadecyl-3-(4'-hydroxy-
0.01 to 1 part by weight, preferably 0.05 to 0.5 part by weight of 3',5'-di-t-butylphenol) propionate (hereinafter abbreviated as ODP), and (B) 0.01 to 0.5 part by weight, preferably silica.
0.05 to 0.2 parts by weight, and further as necessary, (C) Vitamin E: 0.01 to 0.2 parts by weight, or (D) 2,6-di-t-butyl-p-cresol:
0.01 to 0.5 part by weight is added. If the amount of ODP added is less than 0.01 part by weight, there is a risk that the ethylene/α-olefin copolymer () will undergo thermal deterioration during film forming, and if it exceeds 1 part by weight, the film will cause blocking. If the amount of silica added is less than 0.01 part by weight, the blocking resistance of the film will not be improved, and if it exceeds 0.5 part by weight, the transparency of the film will decrease. Furthermore, heat resistance can be improved by adding vitamin E or 2,6-di-t-butyl-p-cresol to the composition of the present invention. Further, by adding 0.3 parts by weight or less of a lubricant, the slip properties of the film can be improved, but if the amount added exceeds 0.3 parts by weight, the blocking resistance decreases. Specific examples of the lubricant include metal soaps such as calcium stearate and zinc stearate, higher fatty acids such as stearic acid and palmitic acid, stearamide, oleic acid amide,
Examples include higher fatty acid amides such as palmitic acid amide and erucic acid amide, and higher fatty acid esters such as oleic acid monoglyceride, butyl stearate and stearic acid monoglyceride.Among them, higher fatty acid amides have a small rate of decrease in blocking resistance, and in particular, Erucic acid amide is preferred because it can impart slip properties without substantially reducing blocking resistance. In order to obtain the ethylene/α-olefin copolymer composition of the present invention, the ethylene/α-olefin copolymer (), each additive (A), (B), and (C) or (D) within the above-mentioned range, such as a method of mixing with a V-blender, tumbler blender, Henschel mixer, ribbon blender, etc., and then melt-kneading with a single-screw extruder, multi-screw extruder, etc. A method of granulating, or a method of melt-kneading and granulating using a kneader, Banbury mixer, etc. can be adopted. The composition of the present invention further contains various additives that are usually added to polyolefins, such as weathering stabilizers, rust preventives, antifogging agents, pigments, dyes, nucleating agents, and antistatic agents. They may be blended within a range that does not impair the purpose. In addition, high-pressure low-density polyethylene, ethylene/vinyl acetate copolymer, high-density polyethylene, amorphous or low-crystalline ethylene and propylene, or 1-
A copolymer with butene or the like may be added. The ethylene/α-olefin copolymer composition for film molding of the present invention can be applied not only to ordinary inflation film molding and T-die film molding, but also to air-cooled two-stage cooling inflation film molding, and water-cooled two-stage cooling inflation film molding. By rapid cooling methods such as inflation film molding, it is possible to obtain a film that does not cause blocking and has excellent opening properties even when used for molding to impart transparency, and even when the molding speed is increased, transparency and It has suitability such as not impairing blocking resistance. The film obtained from the ethylene/α-olefin copolymer composition for film forming of the present invention has excellent transparency, impact strength, tear strength, and low temperature properties, which are the characteristics of the ethylene/α-olefin copolymer (). It has heat-sealing properties, hot-tack properties, and heat resistance, so it can be used as a single film for sugar bags, cleaning packaging bags, water packaging bags, fruit and vegetable packaging bags, standard bags, powder packaging bags, oil packaging bags, etc. It is suitable for various packaging films, and furthermore, a film made of the composition is used as an inner layer and an outer layer is made of polypropylene, high-density polyethylene, nylon, polyester, cellophane, ethylene/vinyl alcohol copolymer, polypynylidene chloride, etc. The various films described above can be used as a layer or a multilayer film of three or more layers. 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 it goes beyond the gist thereof. Example 1 MFR: 1.2g/10min, density: 0.930g/cm ³ , X
100 parts by weight of ethylene/4-methyl-1-pentene copolymer (hereinafter abbreviated as EMP-) with linear crystallinity of 57.5%, melting point of 124°C, and molecular weight distribution of 4.1 and ODP (trade name: Irganox-1076 Musashino Geigy) ) 0.05 parts by weight, silica (product name: Daicalite)
A composition () was obtained by mixing 0.10 parts by weight of WF) and a rust preventive agent in a Henschel mixer and then granulating it in an extruder. Next, the composition () was supplied to an air-cooled two-stage cooling inflation film molding machine equipped with a 50 mmφ extruder (set temperature: 180°C), and
mmφ circular die (die lip: 1.2mm,
Extruded from (setting temperature: 170℃), fold width 230mm x thickness
A 30μ film was obtained. Next, the performance of the film was evaluated by the following method. Haze (%): ASTM D 1003 Blocking power (BL: g/cm): ASTM D
1893, however, as a film adjustment, a load of 10 kg/10 cm ² was applied at a temperature of 50°C for 1 day.
It was left unloaded for 7 days and 30 days at a temperature of 23°C for 1 day. Slip property: Static friction coefficient μs and dynamic friction coefficient μk were determined in accordance with ASTM D 1894. However, in order to adjust the film, it was left at a temperature of 23°C for 1 day and 7 days, and at a temperature of 40°C for 7 days. Film dart impact (DI: g): ASTM
D 1709 Heat resistance: A 30μ thick air-cooled inflation film is passed through a scanning flaw detector (manufactured by Yaskawa Electric Co., Ltd.) to quantify the number of fretting eyes. At this time, a small flexible eye is 0.1 to 0.2 mm, and a medium is 0.2 to 0.2 mm.
0.3mm, large is defined as 0.3mm or more. Heat resistance is determined to be good if the number of large, medium, or small flexible eyes does not increase when a continuously molded film is sampled every hour and subjected to a scanning flaw detector. Also, observing the side color of the wound film and not seeing any change is proof that the film has good heat resistance. The results are shown in Table 1. Examples 2 and 3 The same procedure as in Example 1 was conducted except that the amounts of ODP used in Example 1 were changed to 0.10 parts by weight and 0.20 parts by weight, respectively. The results are shown in Table 1. Examples 4 and 5 In the formulation of Example 3, as a lubricant,
0.06 oleic acid amide and erucic acid amide each
The same procedure as in Example 1 was carried out except that part by weight was added. The results are shown in Table 1. Comparative Example 1 Instead of ODP used in Example 1, tetrakis[methylene-3-(3,5-di-t-butyl-
The same procedure as in Example 1 was carried out, except that 0.10 parts by weight of 4-hydroxy-phenyl)propionate]methane (trade name: Irganox-1010, manufactured by Masashino Geigy) was added. The results are shown in Table 1. Example 6 Instead of the composition () used in Example 1,
MFR: 2g/10min, density: 0.929g/cm ³ , X-ray crystallinity: 55.2%, melting point 123℃ (120℃ and
100 parts by weight of ethylene/4-methyl-1-pentene copolymer (hereinafter abbreviated as EMP-) with a molecular weight distribution of 2.5, ODP: 0.15 parts by weight, silica: 0.10 parts by weight, Elca Acid amide:
The same procedure as in Example 1 was carried out except for using the composition (2) consisting of 0.05 parts by weight and 0.10 parts by weight of rust preventive. The results are shown in Table 1. Example 7 The same procedure as in Example 1 was carried out except that 0.02 parts by weight of vitamin E was added as a heat stabilizer to the formulation of Example 3. The results are shown in Table 1. Example 8 In the formulation of Example 3, 2,6-di-t-butyl-p-cresol was further added as a heat stabilizer.
The same procedure as in Example 1 was carried out except that 0.1 part by weight was added. The results are shown in Table 1. 【table】

Claims (1)

[Claims] 1. Melt flow rate is 0.5 to 20g/
10 min, a copolymer of ethylene and α-olefin having 4 to 20 carbon atoms () having a density of 0.915 to 0.940 g/cm ³ , a crystallinity of 40 to 65% by X-rays, and a melting point of 115 to 130°C: (A) n-octadecyl-3-(4'-hydroxy-
(3,5'-di-t-butylphenol) propionate: 0.01 to 1 part by weight, (B) Silica: 0.01 to 0.5 part by weight, and further as necessary, (C) Vitamin E: 0.01 to 0.2 part by weight, or , (D) 2,6-di-t-butyl-p-cresol:
An ethylene/α-olefin copolymer composition for film forming, characterized in that it contains 0.01 to 0.5 parts by weight.