JP2542330B2 - Highly transparent ethylene resin film - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a highly transparent ethylene resin film. The film of the present invention is used for packaging articles such as foods, clothing, vegetables, fruits, flowers, miscellaneous goods, stationery, household items, machine parts, electronic parts, toys, pharmaceuticals, agricultural chemicals, coins, batteries, cards, and plastic envelope tapes. It is preferably used in the field of displays, displays and the like.

[0002]

2. Description of the Related Art Conventionally, as transparent films, polyester, nylon, polycarbonate, vinylon, polystyrene, cellophane, polypropylene, polyvinyl chloride,
Although there are those made of polyethylene etc., among these, polyethylene-based film is excellent in flexibility, tensile strength, transparency, water resistance, processability, etc., and is the cheapest,
Most used as various packaging materials. Among the polyethylene film materials, polyethylene produced by the high-pressure radical polymerization method is used in large amounts because it has relatively high transparency and good processability, but it is mainly used for light packaging because of its poor mechanical strength. It is used. In recent years, due to advances in polymerization catalysts and polymerization methods, ethylene can be produced by low-pressure gas phase method, liquid phase method or solution method in the presence of chromium-based catalysts, vanadium-based catalysts, titanium-based catalysts, Ziegler-based catalysts, and Phillips-based catalysts. Butene-1, pentene-1, hexene-1, heptene-1, octene-as the main component
1, nonene-1, decene-1, 4-methyl-pentene-
Density obtained by copolymerizing 1 to 2% by weight of 0.910
A linear low-density ethylene-α-olefin copolymer (hereinafter, also referred to as LLDPE) of 0.940 g / ml has come to be produced. These are superior in tensile strength, impact strength, rigidity, heat seal strength, etc. compared to conventional long-chain branched ethylene polymers produced by the high-pressure radical polymerization method, so fertilizers such as ammonium sulfate and urea, caprolactam and surfactants are used. It is used as a heavy packaging bag for industrial chemicals such as rice, rice grains such as rice, wheat, corn and soybeans, or as a light packaging bag for foods, sundries and the like in the form of a thin film. However, the LLDPE is slightly inferior in transparency to a long-chain branched ethylene polymer produced by a high-pressure radical polymerization method, and thus has not been used in a field of application where high transparency is required.

[0003]

Recently, in each industrial field, high-quality and low-priced packaging materials are required, and polyethylene films are also required to have high strength, high transparency and low price. However, in order to satisfy this requirement, a long-chain branched ethylene polymer cannot cope with high strength and a high-density polyethylene cannot cope with transparency, so it has high strength. L, which is slightly less transparent
It is desirable to improve the transparency of LDPE in some way and significantly. Therefore, the present invention relates to LLDPE.
, Whose transparency is comparable to that of a water-cooled film, and has excellent processability, mechanical strength, impact resistance, heat resistance, low temperature resistance, chemical resistance, flexibility and handleability. The problem was to provide an ethylene resin film.

[0004]

The present inventors have found that the LLDP
In order to improve the transparency of E, when a film was produced from a kneaded product in which a long-chain branched ethylene copolymer having better transparency than LLDPE was blended with LLDPE, it was found that the transparency was increased, and this was used as a commercial product. Turned into However, demands from customers for further transparency are strict, and in order to meet such demands, a compound selected from a large number of polymers, organic compounds and inorganic compounds is used as the resin component of LLDPE and a long-chain branched ethylene-based copolymer. As a result of blending to produce a film and examining its transparency, it was found that good results were obtained when a specific amount of a specific inorganic compound was compounded, and further studies were conducted to complete the present invention.

That is, the present invention has a density of 0.910.
0.940 g / ml, melt index 0.5-5 g
Short chain branched linear low density ethylene-α-olefin copolymer 50 to 95 parts by weight for 10 minutes and a density of 0.915 to 0.942 g / ml produced by a high pressure radical polymerization method,
100 parts by weight of a resin component consisting of 50 to 5 parts by weight of a long-chain branched ethylene polymer having a melt index of 0.5 to 10 g / 10 min, an average secondary particle diameter of about 5 μm or less, and a BET specific surface area of The following formula I is about 30 m ² / g or less: (M ²⁺ ) _1-x Al _x (OH) ₂ (A ^n- ) _{x / n} · mH ₂ O (I) (wherein, M ²⁺ is Mg Or represents a divalent metal ion of Zn, A ⁿ⁻ represents an n-valent anion, and x and m represent the following conditions: 0 <x <0.5, and 0 ≦ m ≦ 2. The present invention relates to a highly transparent ethylene resin film produced from a resin composition containing 0.05 to 1 part by weight of hydrotalcite.

Density in the present invention 0.910 to 0.94
The short-chain branched linear low-density ethylene-α-olefin copolymer (LLDPE) having a melt index of 0 g / ml and a melt index of 0.5 to 5 g / 10 min is a known method, that is, a transition metal compound as a main catalyst. (Eg compounds such as titanium and vanadium), organometallic compounds (eg organoaluminum) as co-catalysts, Ziegler type catalysts comprising carriers (eg oxides or chlorides of silicon, titanium, magnesium etc.), chromium type catalysts, etc. It is obtained by polymerizing ethylene and α-olefin in the presence of medium pressure or low pressure. α-olefins are propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-
1, nonene-1, decene-1, 4-methylpentene-1
Etc. are suitable. The polymerization is carried out by various methods such as slurry polymerization, gas phase polymerization and high temperature dissolution polymerization. The LLDPE used in the present invention has a density of 0.910.
0.940 g / ml, which is 0.910 g / m
If it is less than 1, blocking of the film will occur and 0.94
When it exceeds 0 g / ml, transparency and flexibility are deteriorated, which is not desirable. The melt index of LLDPE is 0.5 to 5 g / 10 minutes, which is 0.5 g /
If it is less than 10 minutes, the processability of the film is poor, and if it exceeds 5 g / 10 minutes, the mechanical properties of the film are deteriorated, which is not desirable.

The long-chain branched ethylene polymer produced by the high-pressure radical polymerization method in the present invention has a density of 0.915 to 0.942 g / ml and a melt index of 0.5 to 10 g / 10 min. Ethylene and other α
-Olefins such as propylene, butene-1, 4-methylpentene-1, hexene-1, octene-1, nonene-1, decene-1, tetradecene-1, octadecene-1 etc., or other unsaturated group-containing monovalent Polymers such as styrene, α-methylstyrene, p-methylstyrene, tert-butylstyrene, allylbenzene, butadiene, isoprene, chloroprene, vinyl fluoride, vinyl chloride, vinyl bromide, vinylidene fluoride, vinylidene chloride, bromide Vinylidene, tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, dichlorodifluoroethylene, vinyl acetate, vinyl propionate, methyl acrylate, ethyl acrylate, butyl acrylate, octyl acrylate, stearyl acrylate, methacrylic acid Methyl, octyl methacrylate Stearyl methacrylate, methacrylic acid, itaconic acid, methylene glutaric acid, itaconic anhydride, methyl vinyl ketone, phenyl vinyl ketone, ethyl vinyl ketone, methyl isopropenyl ketone, methyl vinyl ether, ethyl vinyl ether, phenyl vinyl ether, vinyl thioether, acrylonitrile,
Acrylamide, acryldimethylamide, dimethylaminoethyl methacrylate, 2-hydroxyethyl acrylate, glycerin methacrylate, glycidyl acrylate, glycidyl methacrylate, allyl acrylate,
Allyl methacrylate, ethylene glycol diacrylate, divinyl ether, N-vinylpyrrolidone, N-vinylimidazole, ethylmaleimide, N-vinylphthalimide, vinylpyridine, N-vinylcarbazole,
N-vinyl-N-methylacetamide, N, N-dimethylaminoethyl acrylate, tert-butyl acrylamide, methacrylamide, tert-butyl aminoethyl methacrylate, vinyl sulfide, trimethoxy vinyl silane, triethoxy vinyl silane, γ-methacrylopropyl trimethoxy It is a resin obtained by copolymerizing silane, vinyltrichlorosilane, diphenylmethylvinylsilane, etc., and is typically a high pressure polyethylene, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer. Examples thereof include a combination (EEA), an ionomer, and an ethylene-methyl methacrylate copolymer (EMMA). The long-chain branched ethylene polymer used in the present invention has a density of 0.915 to 0.942 g / m.
However, if it is less than 0.915 g / ml, mechanical strength and heat seal strength are deteriorated, film blocking occurs, and in the case of ethylene homopolymer, less than 0.93 g / ml can be produced. In the case of a copolymer of ethylene and another monomer, it is possible to manufacture a copolymer having a high density, but a copolymer having a density of more than 0.942 g / ml has a large comonomer content and causes blocking, which is not desirable. Further, the melt index of this polymer is 0.5 to 10 g / 10 minutes, which is 0.5
If it is less than 10 minutes, the workability and the transparency will be deteriorated.
When the amount is more than ml, the mechanical strength of the film, the heat seal strength and the like are lowered, and further blocking occurs, which is not desirable.

In the present invention, the above LLDPEs 50 to 9 are used.
5 parts by weight and 50 to 5 parts by weight of the long-chain branched ethylene polymer are blended so that the total amount becomes 100 parts by weight to obtain a resin component. When the LLDPE is less than 50 parts by weight, the mechanical strength of the film, the impact resistance, the waist of the film, etc.
The preferable performance of LDPE was not obtained, and 95% by weight
If it exceeds, the transparency and processability of the film are not improved, which is not desirable.

In the present invention, hydrotalcite means
The following formula I having an average secondary particle diameter of about 5 μm or less and a BET specific surface area of about 30 m ² / g or less: (M ²⁺ ) _1-x Al _x (OH) ₂ (A ^n- ) _{x / n} MH ₂ O (I) (wherein, M ²⁺ represents a divalent metal ion of Mg or Zn, A ⁿ⁻ represents an n-valent anion, and x and m represent the following conditions: 0 <x < 0.5, 0 ≦ m ≦ 2 is represented). In the above formula I, A
the following compounds can be given as a n-valent anion represented by ^{n-: Cl -, Br -,} I -, NO 3 -, ClO 4 -,
SO ₄ ²⁻ , CO ₃ ²⁻ , SiO ₃ ²⁻ , HPO ₄ ²⁻ , HBO
₃ ²⁻ , PO ₄ ³⁻ , Fe (CN) ₆ ³⁻ , Fe (C
_{^{N) 4 4-, CH 3 COO}} -, C 6 H 4 (OH) CO
O ^-, The above-mentioned hydrotalcite has an average secondary particle diameter of about 5 μm.
Hereinafter, for example, about 0.1 μm to about 5 μm, preferably about 4
μm or less, more preferably about 3 μm or less, especially about 2 μm
And a BET specific surface area of about 30 m ² / g or less, for example about 1 to about 30 m ² / g, preferably about 25 m ²
/ G or less. These average secondary particle size conditions and B
The use of hydrotalcite that deviates from the ET specific surface area condition is accompanied by a substantial deterioration in the transmittance of visible light, and tends to adversely affect the moldability and physical properties of the film. Particle size conditions and BE
Those represented by Formula I that satisfy the T specific surface area condition are used. In the present invention, the average secondary particle diameter is determined by the following measuring method. A sample of about 2-3 mg was collected on a glass plate, and then an appropriate amount of dispersion medium (trade name:
Add Dythrite) and knead both thoroughly with a spatula. Then, a small amount of cyclohexanol is added to this system to dilute it. One drop of this diluted solution is collected on a slide glass, and the top of the slide is covered with a cover glass. The sample thus obtained is placed in a microscope, the image is transferred to a television image and the number of particles per maximum diameter is automatically counted. 20 different visual fields are selected for each sample and the same operation is repeated, and the average thereof is taken as the average secondary particle diameter of the sample. In the present invention, hydrotalcite is blended in an amount of 0.05 to 1 part by weight based on 100 parts by weight of a resin component composed of LLDPE and a long-chain branched ethylene polymer, which is less than 0.05 part by weight. When the amount exceeds 1 part by weight, the transparency of the film is adversely affected.

In the resin composition used in the present invention, other known additives such as weather resistance improver, antioxidant, processability improver, antistatic agent, antifogging agent, slip agent, lubricant,
Release agents, anti-blocking agents, freshness-retaining agents, dyes, pigments, flame retardants, fragrances, antifungal agents, etc. may be added.

The resin composition of the present invention is LLDP.
E, a long-chain branched type ethylene polymer and hydrotalcite, and optionally other additives are sufficiently kneaded by an extruder, a kneader, a Banbury mixer or a Busco kneader. Further, as a method for producing the highly transparent film of the present invention, the resin composition obtained as described above is melted by an extruder, and after extrusion from a die,
The inflation method by air cooling or water cooling or the T die casting method using a cooling roll can be mentioned. The thickness of the highly transparent film of the present invention is not particularly limited, but 5-100 μm is suitable. This is because if it is less than 5 μm, the strength tends to be insufficient, and if it exceeds 100 μm, the transparency tends to deteriorate.

[0012]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited thereto. Example 1 a. Preparation of raw material resin composition Density 0.923 g / ml, melt index 0.8 g
/ 10 min LLDPE (manufactured by Nippon Unicar, manufactured by Unipol method) 70 parts by weight, density 0.923 g / ml, melt index 0.8 g / 10 min long chain branched ethylene polymer (manufactured by Nippon Unicar, high pressure radical) Manufactured by polymerization method)
30 parts by weight, average secondary particle size 0.4 μm, BET specific surface area 15 m ² / g, chemical composition Mg _0.66 Al _0.34 (OH) ₂
(SiO ₃ ²⁻ ) _0.17 · 0.52H ₂ O hydrotalcite (manufactured by Kyowa Kagaku) 0.4 part by weight, erucic acid amide 0.07 part by weight, stearic acid amide 0.03 part by weight,
Hindered phenolic antioxidant (trade name: Irganox
1010) 0.05 part by weight and 0.05 part by weight of a phosphorus-based antioxidant (trade name: Sandstab P-EPQ) were kneaded with a Banbury mixer at 160 ° C for 10 minutes, and then granulated with a diameter of 3 mm and a length of 3 mm. A cylindrical pellet of was obtained. b. Manufacture of blown film 30 μm thick by air cooling method under the following equipment and processing conditions
Was manufactured. (1) Extrusion device: φ40 mm blown film manufacturing device (manufactured by Placo Co., Ltd.) (2) Die: φ75 mm die (die gap = 2.5)
mm, extrusion temperature = 180-220 ° C., manufactured by Modern Machinery Co., Ltd.) (3) Cooling device: with single lip straight and conical color (4) Discharge rate: 15 kg / hour (5) Frost line: 200 mm (6) Expansion ratio : 2.0 c. Evaluation of Film (1) Workability: Good. It has bubble stability and constant film thickness accuracy. (2) Haze (according to ASTM D1003): 2.8
% (Very good) (3) Gloss (according to ASTM D2457): Incident angle 4
In the case of 5 °, 85 (good) (4) Tensile strength (according to ASTM D882): longitudinal direction 360 kg / cm ² , lateral direction 305 kg / cm ² (5) elongation (according to ASTM D882): longitudinal direction 64
0%, transverse 860% (6) (according to ASTM D882) yield strength: machine direction 155 kg / cm ^2, lateral ^{120kg / cm 2 (7) 1} % Sea Kant modulus (waist strength, ASTM
Compliant D882): longitudinal 1700 kg / cm ^2, conforms to the transverse direction 2150kg / cm ² (8) Tear strength (ASTM D 1004): longitudinal 89 kg / cm, lateral 195kg / cm (9) FAR (film appearance, NUC According to the method: The number (X) of fish eyes or lenses in a film area of 1.8 m ² is measured, and (100−X) is taken as a FAR value: 6
0 (Good) (10) Puncture resistance (according to NUC method: using an Instron type extrusion tester, punctured by pushing with a 1 mm needle, and measuring the load when broken): 180 g (11) Antiblocking property: 20 g / 100cm ² (12) Heat seal strength (140 ° C, seal width 5m
m, load 1 kg, sealing time 1 second): 1400 g / 15
mm

Comparative Example 1 Example 1 was repeated except that the long-chain branched ethylene polymer and hydrotalcite were not used in Example 1 and 0.4 part by weight of talc was added as an antiblocking agent.
When the same operation as above was performed, the haze was 8.0% and the transparency was poor. Also, anti-blocking agent (talc)
Although it was blended in the same amount as the hydrotalcite in Example 1, the antiblocking property was still insufficient. Further, when the antiblocking agent was not added, the transparency was slightly improved, but blocking was caused and the film had no commercial value.

Comparative Example 2 The same operation as in Example 1 was carried out except that hydrotalcite was not used and 0.4 part by weight of talc was blended as an antiblocking agent, and the haze was 4 At 0.5%, the transparency was improved over that of Comparative Example 1, but the level was not reached because the conventional polypropylene film was about 3%. Although transparency was slightly improved when no anti-blocking agent was added,
It caused blocking and had no commercial value as a film.

Example 2 a. Preparation of raw material resin composition Density 0.921 g / ml, melt index 0.8 g
/ 10 min LLDPE (manufactured by Nippon Unicar, manufactured by Unipol method) 80 parts by weight, density 0.923 g / ml, melt index 3.2 g / 10 min long-chain branched ethylene polymer (manufactured by Nippon Unicar, high-pressure radical) Manufactured by polymerization method)
20 parts by weight, average secondary particle diameter 3.7 μm, BET specific surface area 4.3 m ² / g, chemical composition Mg _0.66 Al _0.34 (OH)
₂ (CO ₃ ²⁻ ) _0.17 · 0.52H ₂ O hydrotalcite (manufactured by Kyowa Chemical Co., Ltd.) 0.3 part by weight, erucic acid amide 0.
15 parts by weight, 0.03 parts by weight of stearic acid amide, hindered phenolic antioxidant (trade name: Irganox 101
0) 0.05 parts by weight and phosphorus antioxidant (trade name: S
andstab P-EPQ) (0.05 parts by weight) was kneaded with a Banbury mixer at 160 ° C. for 10 minutes, and then with a granulator, cylindrical pellets having a diameter of 3 mm and a length of 3 mm were obtained. b. Manufacture of blown film A blower film manufacturing apparatus having a diameter of 40 mm was used as in Example 1 to manufacture a film having a thickness of 30 μm under the same processing conditions. c. Evaluation of film (1) Workability: good (2) Haze (according to ASTM D1003): 2.3
% (Very good) (3) Gloss (according to ASTM D2457): Incident angle 4
For 5 °, (conforming to ASTM D882) 80 (excellent) (4) Tensile strength: machine direction 525 kg / cm ^2, (conforming to ASTM D882) lateral 295 kg / cm ² (5) Elongation: longitudinal 49
0%, transverse 820% (6) (according to ASTM D882) yield strength: machine direction 160 kg / cm ^2, lateral ^{125kg / cm 2 (7) 1} % Sea Kant modulus (waist strength, ASTM
Compliant D882): longitudinal 2440kg / cm ^2, conforms to the transverse direction 3090kg / cm ² (8) Tear strength (ASTM D 1004): longitudinal 7 kg / cm, lateral 305kg / cm (9) FAR (film appearance, NUC According to the method: The number (X) of fish eyes or lenses in a film area of 1.8 m ² is measured, and (100−X) is taken as a FAR value: 6
0 (Good) (10) Puncture resistance (according to NUC method: using an Instron type extrusion tester, punctured by pushing with a 1 mm needle, and measuring the load when ruptured): 150 g (11) Antiblocking property: 15 g / 100cm ² (12) Heat seal strength (140 ° C, seal width 5m
m, load 1 kg, sealing time 1 second): 1300 g / 15
mm

Comparative Example 3 The same operation as in Example 2 was carried out except that hydrotalcite was not used in Example 2 and 0.3 part by weight of talc was blended as an anti-blocking agent. It reached a transparency level of a conventional polypropylene film of 0.6%, a gloss of 72 and a haze of about 3%.

[0017]

As described in detail above, the present invention provides
LLDP with inferior transparency and anti-blocking property
In order to improve the E film, LLDPE is blended with a long chain branched ethylene polymer and a specific hydrotalcite. A long-chain branched ethylene polymer improves transparency and film-forming property, but this alone does not provide a high level of transparency, and by adding a specific hydrotalcite further, it is comparable to a polypropylene film for the first time. A highly transparent film having a higher transparency can be obtained. The reason why such a highly transparent film can be obtained is not yet known, but at this stage it is considered as follows: (a) Since an LLDPE film has severe blocking, an inorganic antiblocking agent such as talc or silica is blended. It was essential to do so, but these would deteriorate the transparency of the film. However, in the present invention, since hydrotalcite as a catalyst neutralizing agent also plays a role of preventing blocking, it is not necessary to add a generally used blocking inhibitor, and transparency is improved. (B) However, for the reason (a) only, LLDPE
Alternatively, the transparency should be similar to or lower than that of a film produced by adding a long-chain branched ethylene polymer to it, but in the present invention, on the contrary, the transparency is remarkably improved. It is expected that hydrotalcite has some effect on the improvement of transparency in the matrix of LLDPE and long-chain branched ethylene polymer. Although it was known that hydrotalcite does not impair the translucency of a polyethylene film, the present invention not only does not impair the translucency, but also of a film prepared from LLDPE and a long-chain branched ethylene-based polymer. This is a breakthrough improvement in transparency, and such an effect was first confirmed in the present invention. Thus, the ethylene-based resin film of the present invention has significantly improved transparency while maintaining the excellent performance of LLDPE, and thus is inexpensive, has high strength, heat resistance, cold resistance, and water resistance. It has excellent properties such as excellent properties, chemical resistance, impact resistance, puncture resistance, and heat sealability, and the film is flexible and highly transparent. Therefore, the film of the present invention is an article such as food, clothing, vegetables, fruits, flowers, miscellaneous goods, stationery, household items, machine parts, electronic parts, toys, pharmaceuticals, agricultural chemicals, coins, batteries, cards, packaging, plastic envelopes. It can be suitably used in a wide range of fields such as tapes, tapes and displays.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A 64-6041 (JP, A) JP-A 62-10150 (JP, A)

Claims (1)

(57) [Claims] 1. A density of 0.910 to 0.940 g / ml,
Short-chain branched linear low-density ethylene-α-olefin copolymer 50-having a melt index of 0.5 to 5 g / 10 min
From 95 parts by weight and 50 to 5 parts by weight of a long-chain branched ethylene-based polymer having a density of 0.915 to 0.942 g / ml and a melt index of 0.5 to 10 g / 10 min produced by a high pressure radical polymerization method. To 100 parts by weight of the resin component having an average secondary particle diameter of about 5 μm or less and a BET specific surface area of about 30 m ² / g or less, the following formula I: (M ²⁺ ) _1-x Al _x (OH) ₂ (A ⁿ⁻ ) _{x / n} · mH ₂ O (I) (wherein, M ²⁺ represents a divalent metal ion of Mg or Zn, A ⁿ⁻ represents an n-valent anion, and x and m represent High transparency ethylene produced from a resin composition containing 0.05 to 1 part by weight of hydrotalcite represented by the following condition: 0 <x <0.5, which represents a numerical value satisfying 0 ≦ m ≦ 2. Resin film.