JP2002240212A - Packaging material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light shielding packaging material capable of maintaining a mechanical strength such as a tensile strength, a tearing strength together with a conventional impact resistance even by thinning for reducing its cost. SOLUTION: The packaging material comprises a multilayer film obtained by sequentially laminating a heat sealing inner layer, a light shielding intermediate layer and an outer layer. In this case, the intermediate layer and the outer layer each is formed of a resin containing an ethylene-1-hexene copolymer having a 1-hexene structural unit content superposed by using a single site catalyst of 3 to 15 wt.%, a melt flow rate of 0.3 to 5 g/10 min, a density of a range of 0.89 to 0.94 g/cm3 as a main component. The inner layer is formed of a resin composition containing the ethylene-1-hexene copolymer of 25 to 50 pts.wt. and a high pressure method low-density polyethylene of 75 to 50 pts.wt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-shielding packaging material, and more particularly to a packaging material suitable for packaging photosensitive materials such as photographic photosensitive materials.

[0002]

BACKGROUND OF THE INVENTION Conventionally, light-shielding packaging materials have been used for packaging to prevent the contents of foods, pharmaceuticals, beverages, photosensitive materials and the like from being altered by the influence of light. I have. The main characteristics required for such packaging materials include, in addition to light-shielding properties, mechanical properties such as moisture proof, rigidity, tear resistance, and impact resistance, gas barrier properties, heat sealing properties, and antistatic properties. .

[0003] As an example, in the case of a packaging material of a photosensitive material such as a photographic photosensitive material, it is stored in a state where light is completely shielded.
The packaging material is required to have mechanical strength, particularly impact resistance, during handling such as storage.

When a film is used as a packaging material, a photosensitive material or the like is usually placed in a bag whose film is cut and heat-sealed at its end, and the mouth of the bag is heat-sealed and sealed. Therefore, it is required to be excellent in heat sealability and heat seal strength.

[0005] As such a packaging material, a packaging material comprising a polyethylene-based single-layer or multilayer film blended with carbon black as a light-shielding substance is generally known. For example, there is known a packaging material in which kraft paper coated on one side with low-density polyethylene containing carbon black and a polyethylene-based film containing carbon black are point-adhered. Japanese Patent Publication No. 2-2700 proposes a packaging film having at least one polyethylene film containing a light-shielding substance.

For the purpose of improving heat sealability and film formability, an ethylene / α-olefin copolymer polymerized using a single-site catalyst is used for a light-shielding photographic photosensitive material packaging material. It has also been suggested. (For example, JP-A-8-179473, JP-A-1
0-333281)

[0007] In recent years, demands for improving physical properties such as mechanical strength (particularly impact resistance) required for packaging materials have become more and more severe, and there has also been a demand for cost reduction by thinning.

[0008]

SUMMARY OF THE INVENTION The present invention provides a light-shielding wrapping material which can maintain mechanical strength such as tensile strength and tear strength, as well as conventional impact resistance, even if the thickness is reduced to reduce cost. The purpose is to provide.

[0009]

According to the present invention, there is provided a packaging material comprising:
Heat seal inner layer, light shielding intermediate layer, consisting of a multilayer film laminated in the order of the outer layer, the light shielding intermediate layer and the outer layer,
The 1-hexene structural unit content is 3 to 15% by weight, the melt flow rate is 0.3 to 5 g / 10 min, and the density is 0.89 to 0.94, which is polymerized by using a single-site catalyst.
g / cm ³ , which is formed of a resin containing an ethylene / 1-hexene copolymer as a main component, and the heat seal inner layer is formed of the ethylene / 1-hexene copolymer 25 to 50.
It is characterized by being formed from a resin composition containing, by weight, 75 to 50 parts by weight of a high-pressure low-density polyethylene.

In a preferred embodiment of the present invention, the multilayer film comprises a heat-sealable inner layer (A) having a thickness in the range of 25 to 200 μm and a light-shielding composition having a thickness in the range of 50 to 300 μm. Light-shielding intermediate layer (B) containing an agent
And a packaging material comprising an outer layer (C) containing a white or gray-based compounding agent having a thickness in the range of 25 to 200 µm.

Further, the content of the light-shielding compound in the heat seal inner layer (A) is in the range of 1 to 10% by weight, and the content of the antistatic agent is in the range of 1.0 to 7.0% by weight. In
When the content of the light-blocking compound in the light-shielding intermediate layer (B) is 1
It is preferable that the packaging material is in the range of 10 to 10% by weight, and the content of the white or gray compound in the outer layer (C) is in the range of 1 to 7% by weight.

[0012] The packaging material of the present invention is an inflation film obtained by molding the heat-seal inner layer (A), the light-shielding intermediate layer (B), and the outer layer (C) in this order by three-layer blown film molding. Is preferred.

According to the present invention, a packaging material suitable as a packaging material for a photosensitive material is provided.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A packaging material according to the present invention will be specifically described below.

The ethylene / 1-hexene copolymer used in the present invention is a copolymer polymerized in a catalyst system containing a so-called single-site catalyst as a main component. The single-site catalyst refers to a catalyst such as a geometrically constrained catalyst, a metallocene catalyst, or the like, which is compared with a so-called multi-site catalyst in which titanium tetrachloride or the like is supported on magnesium chloride or the like. Specifically, for example, JP-A-60-35007, JP-A-60-35008,
Catalysts described in JP-A-5009, JP-A-3-207703, JP-A-3-234711, JP-A-4-300887 and the like can be mentioned. Examples of the polymerization method include solution polymerization, slurry polymerization, and gas phase polymerization.

And an ethylene / 1-hexene copolymer
1-hexene structural unit content in the ¹³C-NMR spec
3 to 15% by weight, preferably 3 to 15% by weight.
7% by weight, more preferably in the range of 4-6% by weight.
Melt flow rate (according to ASTM D1238; temperature 190 ° C, load
(Measured with a weight of 2.16 kg) is 0.3 to 5 g / 10 min, preferably
0.5 to 2 g / 10 min, more preferably 1.0 to 1.5
g / 10 min, and the density (by the density gradient tube method).
Measurement) 0.89 to 0.94 g / cm^Three,Preferably
0.910 to 0.940 g / cm^Three, More preferably
0.920 to 0.930 g / cm^ThreeIs within the range. Ma
The molecular weight distribution measured by GPC (Mw / Mn;
Mw: weight average molecular weight, Mn: number average molecular weight)
Or 3.0 to 2.0, more preferably 2.5 to 2.
It is in the range of 0.

The packaging material of the present invention comprises an outer layer and a light-shielding intermediate layer composed of a resin containing the ethylene / 1-hexene copolymer as a main component, and 25 to 50 parts by weight of the ethylene / 1-hexene copolymer. Low-density polyethylene 75
To 50 parts by weight, preferably 25 to 48 parts by weight of ethylene / 1-hexene copolymer and high-pressure low-density polyethylene 75
And a multilayer film obtained by laminating a heat seal inner layer made of a resin composition containing up to 52 parts by weight. The content of the ethylene / 1-hexene copolymer contained in the outer layer and the light-shielding intermediate layer may be the same or different for each layer, but is preferably 50 to 100% by weight. -It may consist only of 1-hexene copolymer.

The other resin component contained in each resin layer is preferably a polyolefin resin, and more preferably a polyethylene resin, and is preferably a high-density polyethylene, a high-pressure low-density polyethylene, a medium-density polyethylene, ethylene and an α-olefin. Are exemplified. Specifically, a homopolymer of ethylene, ethylene and other carbon atoms of 3 to
A copolymer with 20 α-olefins (excluding 1-hexene);
1-butene, 1-pentene, 4-methyl-1-pentene, 1
-Octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene and the like.

The high-pressure low-density polyethylene used in the inner layer of the heat seal of the present invention is an ethylene homopolymer. And melt flow rate (according to ASTM D1238, temperature
0.1 ° -3.0g / 1)
0 minutes, preferably in the range of 0.15 to 0.5 g / 10 minutes, and the density in the range of 0.910 to 0.930 g / cm ³ , preferably 0.915 to 0.920 g / cm ³ . The density is measured by a density gradient tube after heat-treating the strand obtained at the time of measuring the melt flow rate at 120 ° C. for 1 hour, gradually cooling it to room temperature over 1 hour.

The preferable swell ratio of the high-pressure low-density polyethylene is 50% or less, more preferably 40%.
It is as follows. The swell ratio is obtained as follows. The diameter at a position 5 mm from the tip of the strand obtained at the time of melt flow rate measurement is measured with a micrometer as the diameter of the sample. Then, it is calculated by the following equation. Swell ratio (%) = {(L ₁ / L ₀ ) −1} × 100 (where L ₁ : sample diameter (mm), L ₀ : orifice diameter (mm))

The high-pressure-process low-density polyethylene as described above is, for example, 1,000 to 2,000 atm, 200 to 30 atm.
It can be produced by a so-called high-pressure method of synthesizing by radical polymerization at 0 ° C.

The multilayer film used for the packaging material of the present invention has at least a heat seal inner layer (A), a light shielding intermediate layer (B), and an outer layer (C). The heat seal layer is
In the case of a bag-shaped packaging material, the edge of the cut film is heat-sealed and bonded, and is usually provided on the innermost layer of the packaging material. Therefore, a light-blocking compound may be added to enhance the light-blocking effect, or an antistatic agent may be added to prevent dust or the like from adhering. The amount of the compound is preferably 1 to 10% by weight. And more preferably 5.0 to 1
0.0% by weight, and the amount of the antistatic agent is preferably 1.0%.
To 7.0% by weight, more preferably 2.5 to 5.0% by weight. The heat seal inner layer is preferably a resin layer having excellent heat sealability, comprising a resin composition containing the ethylene / 1-hexene copolymer and a high-pressure low-density polyethylene.

Here, examples of the light-shielding compounding agent used include metal powders such as carbon black and aluminum, inorganic pigments having a refractive index of 1.5 or more, and powders such as titanium oxide. These light-shielding compounding agents are preferably in the form of fine powder, and are desirably uniformly dispersed in the resin material.

Examples of the antistatic agent include commonly used anionic, cationic and nonionic types.
Surfactant types classified into amphoteric types can be mentioned. As anionic antistatic agents, specifically, fatty acid salts, sulfated oils, sulfated ester oils, sulfated amide oils, olefin sulfates, aliphatic alcohol sulfates, alkyl sulfates,
Aliphatic ethyl sulfonate, alkyl sulfonate, alkyl naphthalene sulfonate,
Examples thereof include alkylbenzene sulfonates.

Specific examples of the cationic antistatic agent include aliphatic amine salts, quaternary amine salts, alkylamine sulfates, quaternary ammonium salts, quaternary ammonium resins, alkylpyridium salts, and morpholine. Derivatives and the like can be exemplified.

Specific examples of nonionic antistatic agents include sorbitan type represented by polyoxyethylene sorbitan monostearate and partial fatty acid esters of polyhydric alcohols such as pentaerythritol and ethylene oxide adducts thereof. , An ethylene oxide adduct of an aliphatic alcohol, an ethylene oxide adduct of a fatty acid, an ethylene oxide adduct of an alkyl phenol,
Examples include polyethylene glycol, an alkylamine, or an ethylene oxide adduct of an aliphatic amide.

Specific examples of the amphoteric antistatic agent include:
Examples thereof include alkylaminocarboxylic acid betaine compounds, alkylimidazoline derivatives, and N-alkyl β-alanines.

The light-shielding intermediate layer preferably contains a light-shielding compounding agent, and is usually provided outside the heat seal layer to block light. Examples of the light-shielding compounding agent include the same as those described above. These light-shielding compounding agents are preferably in the form of fine powder, and are desirably uniformly dispersed in the resin material containing the ethylene / 1-hexene copolymer as a main component.

The content of the light-blocking compound in the light-shielding intermediate layer is as follows:
It is selected depending on the layer thickness and application, but is preferably 1 to 10% by weight, more preferably 5 to 10% by weight. This range is preferable in terms of mechanical strength, economy, and moldability.

The outer layer is preferably laminated outside the light-shielding intermediate layer and contains a white or gray compounding agent. This outer layer is provided, for example, to facilitate confirmation of the location of the packaging material in a dark room or the like, or to reduce light transmittance by reflecting light to further enhance the light blocking effect. As white or gray-based compounding agents, titanium white,
Examples include white pigments and gray pigments.

The content of the white or gray compound in the outer layer is selected depending on the layer thickness and the intended use, but is preferably 1 to 7
%, More preferably 3 to 5% by weight. This range is preferable in terms of mechanical strength, economy, and moldability.

In a preferred embodiment of the packaging material of the present invention,
The multilayer film has the heat seal layer as an inner layer and has a thickness of 25 to 200 μm, preferably 50 to 100 μm.
A heat seal inner layer (A) having a thickness of 50 μm, and a light shielding layer as an intermediate layer having a thickness of 50 to 300 μm, preferably 75 to 300 μm.
Light-shielding intermediate layer (B) containing 200 μm light-shielding compounding agent
Is laminated on the outside of the light-shielding intermediate layer, and has a thickness of 25 to 200.
The outer layer (C) containing a white or gray-based compounding agent having a thickness of 50 µm, preferably 50 to 100 µm, is preferred.

In the present invention, an antioxidant, a weathering stabilizer, a radical absorber, a nucleating agent, etc., which are usually added to the ethylene-based polymer film, may be added to the resin material forming each layer, if necessary. Is added.

The thickness of the entire multilayer film is usually
150 to 700 μm, preferably 180 to 400 μm in terms of mechanical strength and economy, more preferably 190 to 30 μm.
0 μm is preferred.

The packaging material of the present invention is obtained by molding a heat-sealable inner layer (A), a light-shielding intermediate layer (B), and an outer layer (C) into a laminated film in this order. Examples of a method for forming a laminated film include a laminating method, a co-extrusion method, and a multilayer inflation method. Among them, the three-layer inflation method of forming the three-layer laminated film by the multilayer inflation method is preferable because a wide multilayer film can be formed at low cost.

The multilayer film obtained as described above is
A highly useful packaging material having the following physical properties can be obtained. Tear strength 125 g or more Impact strength 20 Kg · cm or more Falling ball impact strength (Method B) 1000 g or more Apparent Young's modulus 2400 Kg / cm ² or more This packaging material has a high light-shielding property and is a photosensitive material such as a photosensitive material. It is suitably used as a packaging material.

[0037]

EXAMPLES (Examples 1 to 6) Using the following resin and compounding agent, a three-layer film having the constitution shown in Table 1 was applied to a resin temperature of 200 using an upper blown die (300 mm in diameter). Molded at ℃ by the multilayer inflation method.

Resin a Ethylene / 1-hexene copolymer polymerized using a sing site catalyst 1-hexene structural unit content 5.0% by weight Melt flow rate 1.0 g / 10 min Density 0.925 g / cm ³ Resin b Ethylene / 1-hexene copolymer polymerized using single-site catalyst 1-hexene structural unit content 5.0% by weight Melt flow rate 1.0 g / 10 min Density 0.930 g / cm ³

The resin c high-pressure low-density polyethylene melt flow rate 0.35 g / 10 min Density 0.919 g / cm ³ light-blocking formulations carbon black Tokyo Ink Co., Ltd. Black # 40 white or grayish formulations Gray Tokyo 8AA066 GRAY manufactured by Ink Corporation

[0040]

[Table 1]

The methods for measuring various physical properties are described below. (1) 1-Hexene structural unit content Measured by ¹³ C-NMR spectrum. (2) Melt flow rate (MFR) Measured according to ASTM D1238. (Temperature 190
(° C) (3) Density Measured according to ASTM D1505. (4) Tensile strength, elongation at break, apparent Young's modulus Measured according to JIS K-6781. (5) Tear strength Measured according to ASTM D1922. (6) Impact strength A film of 100 mm x 100 mm was used as a test piece, which was fixed on a sample table at normal temperature, and used as a pendulum type tester (film impact tester manufactured by Toyo Seiki Co., Ltd., capacity: 30 kg · cm, impact head: 1 / It was determined from the impact fracture energy when the ball was broken at 2 inches (φ). (7) Falling ball impact strength (method B) Measured according to ASTM D1709.

[0042]

The packaging material of the present invention has high light-shielding properties,
Since it has excellent mechanical strength such as impact resistance, tensile strength and tear strength, it can be preferably used as a packaging material for protecting contents affected by light. Above all,
It is suitable for packaging materials for photosensitive materials such as photographic photosensitive materials.
In addition, the cost can be reduced by reducing the thickness, so that the economy is excellent.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 3/22 C08K 3/22 C08L 23/08 C08L 23/08 (72) Inventor Osamu Ishiguro Yokkaichi, Mie Prefecture No. 1 Asahi-cho Mitsui Chemicals Co., Ltd. (72) Inventor Tetsuya Saito 3 Chigusa Kaigan, Ichihara-shi, Chiba Mitsui Chemicals, Inc. In-house F-term (Reference) 3E086 AA01 AB01 BA04 BA15 BB22 BB23 BB85 CA40 4F100 AA37H AK06A AK62A AK05BAK62AL BA03 BA07 BA10A BA10C CA22 CA30 EH20 EH202 GB15 HB00C JA06B JA06C JA13B JA13C JD06 JD06B JL10C JL12A YY00A YY00B YY00C 4J002 BB051 DA036 DA096 DE136 FD100 FD206 GF00 GG00

Claims (5)

[Claims] 1. A multilayer film comprising a heat-seal inner layer, a light-shielding intermediate layer, and an outer layer laminated in this order, wherein the light-shielding intermediate layer and the outer layer are polymerized using a single-site catalyst.
A hexene structural unit content of 3 to 15% by weight, a melt flow rate of 0.3 to 5 g / 10 min, and a density of 0.89 to
0.94 g / cm ³ of a resin containing an ethylene / 1-hexene copolymer as a main component, wherein the inner layer of the heat seal is 25 to 50 parts by weight of the ethylene / 1-hexene copolymer and a high-pressure low-density polyethylene 75 A packaging material comprising a resin composition containing up to 50 parts by weight. 2. The multilayer film according to claim 1, wherein (A) a thickness of 25 to
200 μm heat seal inner layer, (B) thickness 50-30
The packaging material according to claim 1, comprising a light-shielding intermediate layer containing a light-shielding compound of 0 µm, and (C) an outer layer containing a white or gray-based compound having a thickness of 25 to 200 µm. 3. The heat seal inner layer (A) contains 1 to 10% by weight of a light-shielding compounding agent and 1.0 to 7.0 of an antistatic agent.
%, The light-shielding intermediate layer (B) contains 1 to 10% by weight of a light-shielding compounding agent, and the outer layer (C) contains 1 to 7% by weight of a white or gray-type compounding agent. The packaging material according to claim 2, characterized in that: 4. The heat-sealing inner layer (A), the light-shielding intermediate layer (B), and the outer layer (C) are obtained by molding a three-layer blown film in this order. The packaging material described in. 5. A packaging material for a photosensitive material, comprising the packaging material according to claim 1.