JP3112239B2 - Polyolefin laminated film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin-based laminated film having excellent moisture-proof properties and gas barrier properties and suitable for packaging.

[0002]

2. Description of the Related Art Conventionally, polyolefins, for example,
It is known that the addition of petroleum resin and terpene resin to polypropylene can improve Young's modulus and moisture resistance (Japanese Patent Publication No. 1-25033, Japanese Patent Publication No.
No. 31347). It is also known that a metal vapor deposition and a polyvinylidene chloride-based resin are laminated on a film obtained by adding a petroleum resin and a terpene resin to polypropylene to further improve the moisture proof property (Japanese Patent Publication No. 2-27).
No. 940, Japanese Patent Publication No. 5-1138).

[0003]

However, simply adding a petroleum resin and a terpene resin to polypropylene improves the Young's modulus and moisture resistance, but the petroleum resin and the terpene resin have low softening points. The added film is inferior in dimensional stability, and when the film is wound into a roll, the film is tightened to deteriorate the flatness. In addition, there is a problem that the process stability during processing is inferior due to a large heat shrinkage.

Further, when a metal is vapor-deposited on the film to give it a further moisture-proof property, the film is shrunk by heat at the time of vapor deposition, cracks are formed on the metal-deposited surface, and the moisture-proof property is not improved. was there.

[0005] Further, in the case of coating a polyvinylidene chloride-based resin to further impart moisture-proof properties, the film shrinks due to heat during drying after coating, causing cracks in the coating resin layer or polypropylene. There was a problem that the interfacial adhesive strength with the film was lowered and the moisture resistance was not improved.

An object of the present invention is to provide a polyolefin-based laminated film capable of improving the moisture-proof property and the gas barrier property without causing inconvenience in view of the above-mentioned state of the art.

[0007]

According to the present invention, there is provided a polyolefin laminate film according to the present invention comprising a three-layer laminate film.
A polyolefin-based film with a thickness of 10 to 20 μm
The polar group is not substantially contained as one surface layer on the
Terpene tree containing virtually no petroleum resin and polar groups
0.1 to 5% by weight of at least one fat mixed
A layer having a thickness of about 5.0 μm, and
The surface of the other is a heat seal layer
Consisting of those wherein there.

[0008] The discharge treatment is carried out in a CO ₂ and / or N ₂ atmosphere, that is, in an atmosphere in which the concentration of CO ₂ and / or N ₂ is higher than a predetermined concentration, rather than simply performed in air. What is performed is preferred.

[0009]

In the heat seal layer, an inorganic lubricant, for example, a lubricant such as silica particles, alumina particles, and calcium carbonate particles is preferably used only in the heat seal layer.
05 to 5% by weight, more preferably 0.07 to 2% by weight,
It is particularly desirable that the content be 0.1 to 0.5% by weight.

In such a polyolefin-based laminated film, the main component is, for example, polypropylene. That is, it is a polypropylene-based laminated film. The stretching form of the film is not particularly limited, and may be unstretched (unoriented) or uniaxially stretched (uniaxially oriented).
Particularly preferred for packaging and the like is the form of a biaxially stretched film (biaxially oriented film).

Further, in the present invention, the surface of the one surface layer of any one of the above-mentioned polyolefin-based laminated films is subjected to aluminum vapor deposition, and a polyethylene-based film layer is formed on the vapor-deposited surface. A polyolefin-based laminated film characterized in that a biaxially oriented polypropylene-based film layer is laminated on the layer. In the polyolefin-based laminated film of this embodiment, printing can be performed on one surface of the biaxially oriented polypropylene-based film layer, particularly on the surface on the side of the polyethylene-based film layer.

In the present invention, the base material of the film layer in which the petroleum resin and / or terpene resin is mixed is preferably, for example, crystalline polypropylene. Such a crystalline polypropylene has an isothermal crystallization time at 125 ° C. (hereinafter sometimes abbreviated as t-1 / 2) of 6.0 minutes or less and an isotactic index (hereinafter II).
May be abbreviated. ) Is preferably 94.5% or more. t-1 / 2 exceeded 6.0 minutes, II was 9
If it is less than 4.5%, the crystallinity of the film does not increase, and
Heating at 0 ° C. for 15 minutes increases the thermal shrinkage in the longitudinal direction, which is not preferable, and also deteriorates the organic solvent resistance, which is not preferable. In addition, the melt flow index (MFI) is set to 1
When the content is in the range of ／ 4 g / 10 minutes, the dispersibility of the petroleum resin and / or the terpene resin is improved, and the film-forming property and the moisture-proof property are also improved. In addition, a small amount of a second component other than propylene, for example, ethylene, butene, hexene, or the like may be randomly copolymerized. In addition, known additives such as a crystal nucleating agent, an antioxidant, a heat stabilizer, a slipping agent, an antistatic agent, an antiblocking agent, a filler, a viscosity modifier, and a coloring inhibitor may be contained in appropriate amounts.

[0014] In the present invention, the base material of the film layer,
For example, a petroleum resin substantially free of a polar group, which is mixed with crystalline polypropylene, is a petroleum resin having no polar group consisting of a hydroxyl group, a carboxyl group, a halogen group, a sulfone group and a modified form thereof, that is, Cyclopentadiene-based resin directly derived from petroleum unsaturated hydrocarbons or resin derived from higher olefinic hydrocarbons as the main raw material.

The petroleum resin substantially free of such a polar group has a glass transition temperature (hereinafter, abbreviated as Tg) of 60.
It is preferable that the temperature is not lower than ° C. When Tg is less than 60 ° C,
The effect of improving the moisture resistance is small.

A hydrogenated petroleum resin obtained by adding hydrogen to such a petroleum resin and having a hydrogenation rate of 90% or more, preferably 99% or more, is particularly desirable for the polyolefin-based laminated film of the present invention. Representative hydrogenated petroleum resins include, for example, high Tg completely hydrogenated alicyclic petroleum resins such as polydicyclopentadiene having a Tg of 70 ° C. or more and a hydrogenation ratio of 99% or more.

A terpene resin substantially free of a polar group refers to a terpene resin having no polar group such as a hydroxyl group, an aldehyde group, a ketone group, a carboxyl group, a halogen group, a sulfone group, and a modified product thereof. , Ie (C
₅ H ₈₎ is a hydrocarbon and now modified compound derived composition of n. n is a natural number of about 2 to 20.

The terpene resin is sometimes called a terpenoid, and typical compounds include pinene, dipentene, kalen, myrcene, ocimene, limonene, terpinolene, terpinene, sabinene, tricyclene, bisabolene, zingiperene, santalen, camphorene, There are millen and totalene, and in the case of the film of the present invention, hydrogen is added and the hydrogenation rate is 90% or more, preferably 9%.
9% or more, particularly β-pinene, hydrogen β
-Pinene, hydrogenated β-dipentene and the like are preferred.

As described above, the use of at least one of a petroleum resin substantially free of a polar group and a terpene resin substantially free of a polar group is important in the present invention, and the bromine value is preferably 10 or less, more preferably 10 or less. Is preferably 5 or less, more preferably 1 or less.

The mixing amount of at least one of the petroleum resin substantially free of the polar group and the terpene resin substantially free of the polar group contained in the film of the present invention is 70 to 95% by weight of the film base resin. % To 5% by weight. In particular, it is preferably from 10 to 20% by weight. If the mixing amount of the resin is less than 5% by weight, the moisture-proof property is not improved, and if it exceeds 30% by weight, the heat resistance deteriorates, which is not preferable. Further, when the content is close to 40% by weight, film formation becomes impossible due to extrusion trouble.

A polyolefin-based film layer, for example, a polypropylene-based film layer is laminated on such a film layer containing a petroleum resin and / or a terpene resin substantially free of a polar group. The polypropylene-based film layer is not particularly limited, and may be a layer containing polypropylene as a main component and a layer having general dimensional stability. Since this film layer has thermal dimensional stability of the entire laminated film, a film layer containing petroleum resin and / or terpene resin as described above on the surface layer or a thin layer such as a heat seal layer described later is used. Even if you provide
Desirable heat shrinkage and the like can be achieved as a whole of the laminated film. In the present invention, the thickness of the polypropylene-based film layer (hereinafter, also referred to as B layer) is in the range of 10 to 20 μm , and the layer containing petroleum resin and / or terpene resin (hereinafter, referred to as C layer). May be in the range of 0.1 to 5.0 μm.
You.

The surface of the C layer is subjected to a discharge treatment. As described above, the discharge treatment may be a mere discharge treatment in the air. However, from the viewpoint of improving the adhesion to the metal deposition layer provided on the surface, the discharge treatment is performed in an atmosphere of CO ₂ and / or N ₂ . Discharge treatment is more preferred. Where CO ₂
And / or N ₂ atmosphere is, for example, an atmosphere containing CO ₂ or N ₂ singly or more at a certain concentration or more.
_An atmosphere containing a mixed gas of ₂ and N ₂ at a certain concentration or more, and a mixed gas of CO ₂ and Ar, a mixed gas of N ₂ and Ar, or a mixed gas of CO ₂ , N ₂ and Ar at a certain concentration This is the atmosphere that includes the above.

By subjecting the surface of the C layer to such a discharge treatment, the adhesive strength (deposition strength) with a metal vapor deposited layer, for example, an Al vapor deposited layer is significantly increased. Al deposition is performed in a usual manner, for example, in a vacuum vessel (for example, 10 ⁻⁴ to 10 ⁻⁵ T).
orr vacuum container) purity 99.9-99.999%
Al may be deposited.

This metal deposited layer (for example, Al deposited layer)
By providing the film, the gas barrier properties of the laminated film are remarkably enhanced, and the film becomes suitable for packaging of dry matter, potato chips and the like in combination with the moisture-proof property. The gas barrier property is an oxygen permeability (hereinafter, also referred to as O ₂ TR).
O ₂ TR is preferably ² cc / 100 in ² / day or less, more preferably 1.5 cc / 100 in
² / day or less.

In the present invention, a heat seal layer (hereinafter sometimes referred to as an A layer) often provided for packaging and the like is provided on the side opposite to the C layer of the above two-layer laminated film. It provided Ru. That is, it is a three-layer laminated film of A / B / C. The thickness of the layer A is not particularly limited, but may be 0.5-5.
About 0 μm is appropriate. The layer A can be composed of a binary or terpolymer of polypropylene and another polymer, for example, a terpolymer of ethylene-propylene-butene. A suitable temperature for starting the heat sealing is about 90 to 125 ° C.

[0027] Lamination of the heat seal layer in this manner is a method that has been frequently performed in the past. However, in the case of a conventional laminated film having the heat seal layer, a base film is required to improve the slipperiness. Material layer (B layer) and base material layer (B
Layer) and the heat seal layer (A layer) often contain an organic lubricant.

However, when an organic lubricant is contained, a part of the lubricant bleeds out to the surface of the heat seal layer, and is applied to the surface opposite to the heat seal layer surface by blocking when the laminated film is wound into a roll. In some cases, the properties that exert the effect of the improved adhesion property (for example, discharge treatment for improving the Al deposition strength) may be peeled off. Therefore, as a result, the Al deposition strength may be reduced. Also, when the organic lubricant bleeds out to the deposition surface side, the lubricant bleed out at the time of deposition evaporates and Al
There is also a possibility that a pinhole or the like is generated in the deposited film.

Therefore, in the present invention, when a three-layer laminated film having a heat seal layer is used, it is preferable that the heat seal layer contains not an organic lubricant but an inorganic lubricant which does not easily bleed out. That is, an inorganic lubricant is used as an anti-blocking agent. The inorganic lubricant as an anti-blocking agent is contained only in the heat seal layer (A layer), and the base layer (B layer)
It is preferable not to bleed out to the vapor deposition surface side of the C layer through.

By including an inorganic lubricant in the heat seal layer as described above, the rejection rate of the product due to blocking can be reduced. The occurrence of defects can be prevented.

In particular, in order to suppress blocking, the slip coefficient μs / μd (static friction coefficient / dynamic friction coefficient) of the film surface is calculated as ((0.4-0.9) / (0.3-0.8)).
It is preferable to keep

In the present invention, a metal vapor-deposited film (for example, an Al vapor-deposited film) is provided on the surface of the C layer of the two-layer (B / C) or three-layer (A / B / C) laminated film as described above. In addition, a polyethylene film layer is laminated on the metal vapor-deposited film, and a biaxially oriented polypropylene film layer is further provided thereon, so that a laminated film form suitable for packaging can be adopted. The surface of the biaxially oriented polypropylene film layer on the side of the polyethylene film layer can be printed.

The biaxially oriented polypropylene film is not particularly limited, and has a slip coefficient μs / μd of ((0.
15-0.5) / (0.15-0.5)). Further, for the polyethylene film layer, for example, polyethylene or a mixture of polyethylene and ethylene methacrylate or ethylene methacrylate can be applied.

Further, in this kind of laminated film, when the heat-sealing layer is provided as the outermost layer on the opposite side to the biaxially oriented polypropylene-based film layer, the heat-sealing layer has a thickness of 0.5 to 3. About 0 μm,
A suitable temperature for starting the heat sealing is about 90 to 125 ° C.

Next, an example of the method for producing the heat and moisture resistant film of the present invention will be described. For example, t-1 at 125C
/ 2 is 6.0 minutes or less, II is 94.5% or more, and
An extruder is used to extrude a C-layer resin comprising a mixture of a specific range of a petroleum resin substantially free of polar groups and a terpene resin substantially free of polar groups in crystalline polypropylene having a melt flow index of 1 to 4 g / 10 minutes. C, and the resin temperature is 200 ° C. or higher, preferably 220 ° C. to 29 ° C.
The resin is melt-extruded at a temperature of 0 ° C., the B-layer resin is supplied to an extruder B and extruded at a resin temperature of 240 ° C. to 320 ° C., and a resin obtained by adding a predetermined amount of an inorganic lubricant to the A-layer resin or the A-layer resin is extruded by an extruder A
And extruded at a resin temperature of 240 ° C to 300 ° C.
It is discharged as a three-layer laminated sheet of C layers. This molten laminated sheet is cast on a cooling drum controlled to a surface temperature of 20 to 60 ° C. and solidified by cooling to produce an unstretched laminated film.

The unstretched film is heated at 135 to 165 ° C.
Stretched 4.0 to 5.0 times in the longitudinal direction, and 15 to
It is cooled at 50 ° C. to obtain a uniaxially stretched laminated film. Subsequently, the uniaxially stretched film was guided to a tenter,
It is preheated to 180 ° C., stretched 7 to 12 times in the width direction, and heat-treated after stretching. The surface of layer C of the obtained biaxially stretched laminated film is subjected to corona discharge treatment in an atmosphere of, for example, CO ₂ , N ₂ , or a mixed gas of CO ₂ and N _2, and is wound up after the treatment. After winding, an aging process is performed as necessary, and the product is slit into a product having a predetermined width. Then, metal evaporation, for example, aluminum evaporation is performed on the surface of the C layer as necessary.

[Method of Measuring Characteristics and Method of Evaluating Effect]
The method for measuring the characteristic values and the method for evaluating the effects of the present invention are as follows. (1) Isotactic index (II) In the state of the raw material, it may be measured individually. In the case of a composite film, first, a sample is extracted with n-heptane at a temperature of 60 ° C. or less for 2 hours, and the additive to propylene is added. Is removed.
Thereafter, vacuum drying is performed at 130 ° C. for 2 hours. From now on weight W
Take (mg) sample, place in Soxhlet extractor and extract with boiling n-heptane for 12 hours. Next, the sample is taken out, sufficiently washed with acetone, vacuum-dried at 130 ° C. for 6 hours, and then cooled to room temperature, the weight W ′ (mg) is measured, and it is determined by the following equation. II (%) = (W ′ / W) × 100 For the composite layer, the surface layer may be scraped off and measured by the same method as described above.

(2) Glass transition point temperature (Tg), isothermal crystallization time (t-1 / 2) In the state of the raw material, the temperature may be measured individually. For 2 hours to separate propylene from petroleum resin and terpene resin. Then, propylene is vacuum dried at 130 ° C. and petroleum resin and terpene resin are dried at 60 ° C. for 2 hours. Then, for each sample, a differential scanning calorimeter (DSC-
2 type, manufactured by PerkinElmer Co., Ltd.)
When the temperature was raised from room temperature at a rate of 20 ° C./min, the change in specific heat accompanying the second-order transition type was defined as the glass transition temperature (Tg), and then to the melting holding temperature of 280 ° C. After raising the temperature and holding for 5 minutes, the mixture was cooled at a cooling rate of 20 ° C./min. When the temperature was held at 125 ° C., the start time and end time of the peak of the latent heat accompanying crystallization were recorded. Half the time was taken as the isothermal crystallization time (t-1 / 2). In addition, about a composite layer, what is necessary is just to scrape a surface layer, and to measure by the same method as the above.

(3) Melt flow index (MF)
I) 230 ° C., 2.16 according to ASTM-D-1238
It was measured under the condition of kg.

(4) Bromine value Measured according to JIS-K2543-1979. It is represented by the number of g of bromine added to the unsaturated component in 100 g of the sample oil.

(5) Heat Shrinkage The heat shrinkage is sampled at a test length of 260 mm and a width of 10 mm, and a mark is placed at a position of 200 mm as the original size (L0). A load of 3 g was applied to the lower end of the sample, and 12
Heat treatment is performed in an oven at 0 ° C. for 15 minutes, after which the length (L1) marked on the sample is measured. This heat shrinkage (R) is obtained by the following equation. Heat shrinkage (R) (%) = [(L ₀ −L ₁ ) / L ₀ ] × 1
00

(6) Film thickness The film thickness was measured using a dial gauge type thickness meter (JIS-B7509).

(7) Lamination Thickness The film cross-sectional structure was observed using a field emission scanning electron microscope (FE-SEM), and the thickness was measured.

(8) Slip coefficient μs / μd Measured in accordance with ASTM-D1894-93.

(9) Measurement of Al Deposition Strength Surlyn was heat-sealed on the Al-deposited film surface (1).
At 20 ° C. × 1 second), the vapor-deposited film and the Surlyn layer were pulled apart at a peeling speed of 300 m / min in the opposite direction by 180 ° using a tensile tester (Tensilon), and the peel strength at that time was measured. The unit is g / sample width 1 inch.

(10) Oxygen permeability O ₂ TR Measured using a commercially available oxygen permeability measuring device (unit: c)
c / 100 in ² / day).

(11) Inspection of Blocking The vapor deposition film was rewound from the vapor deposition reel around which the aluminum vapor deposition film was wound, and the size and number of pinholes on the vapor deposition surface were compared with a limited sample (visually), and the pass / fail was measured. The percentage of rejects in all products was expressed as the rejection rate (%) due to blocking.

[0047]

The present invention will be described below based on examples and comparative examples. Examples 1-3 Crystalline polypropylene (PP) (t
-1/2: 4.5 min, II: 95.5%, MFI: 1.
7g / 10min) 1 specific hydrogenated non-polar petroleum resin
Using a resin composition mixed in a ratio of 5% by weight (Examples 1 and 2) and 10% by weight (Example 3), the resin composition was supplied to an extruder C and mixed.
Heat sealing at a temperature of 55 ° C., supplying ordinary PP as a resin for layer B to extruder B and melting at 280 ° C., and adding inorganic particles as a resin for layer A to a PP resin as an antiblocking agent The resin for the layer was supplied to the extruder A and melted at 270 ° C.

Each molten resin is sent to a three-layer composite die through a filter, laminated and discharged in three layers of A / B / C layers,
It was cooled and molded and solidified on a cooling drum having a surface temperature of 30 ° C. The unstretched film (sheet) was preheated to 150 ° C, stretched 4.3 times in the longitudinal direction, and then cooled at 30 to 40 ° C. Subsequently, the obtained uniaxially stretched film was supplied to a tenter, preheated at 160 ° C., stretched 10 times in the width direction, and then heat treated (heat set). The surface of the C layer of the obtained biaxially stretched laminated film was subjected to corona discharge treatment in a CO ₂ and N ₂ mixed gas atmosphere, and then wound up (however, in Example 2, the corona discharge treatment is usually performed in air). The thickness configuration of each layer of the obtained three-layer laminated biaxially stretched film is as shown in Table 1. Table 1 shows the properties of the obtained film with respect to O ₂ TR, blocking rejection rate, and Al deposition strength.
Shown in

In Example 1, the film was excellent in both O ₂ TR, blocking rejection rate, and Al deposition strength. In Example 2, the corona discharge treatment was usually performed in air, so the blocking rejection rate was slightly reduced. Although it increased and the Al deposition strength decreased slightly, both were satisfactory values. In Example 3, since the proportion of the petroleum resin was reduced, the O ₂ TR and the blocking rejection rate were slightly increased.
(1) Although the deposition strength was slightly reduced, all values were sufficiently satisfactory.

Comparative Examples 1 to 3 In Comparative Examples 1 and 2, a two-layer laminated film having an A / B layer was used, and neither petroleum resin was contained. In Comparative Example 1, since the organic particles were added to the antiblocking agent, the blocking rejection rate was excellent, but the O ₂ TR was greatly increased and the Al deposition strength was greatly reduced. In Comparative Example 2, the blocking rejection rate was significantly increased because no antiblocking agent was contained, and the Al deposition strength was low because no petroleum resin was contained. In Comparative Example 3, since the ratio of the petroleum resin in the C layer was too high at 40% by weight, an extrusion trouble occurred and a film could not be formed.

[0051]

[Table 1]

[0052]

As described above, the polyolefin-based laminate film of the present invention is a discharge-treated laminate film in which a specific amount of a petroleum resin and / or a terpene resin is added to a specific layer and mixed. In addition to having excellent moisture resistance, the metal vapor deposition film has excellent adhesive strength, can exhibit excellent gas barrier properties, and can also minimize the occurrence of rejects due to blocking.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 1/00-35/00

Claims (5)

(57) [Claims] 1. A three-layer laminated film having a thickness of 10 to 10.
On a 20 μm polyolefin-based film layer,
Petroleum resins and poles substantially free of polar groups as surface layers
One or more terpene resins substantially free of a functional group
A layer having a thickness of 0.1 to 5.0 μm mixed with 30% by weight
Provided, and the surface of the layer is subjected to discharge treatment.
Wherein the other surface layer is a heat seal layer . Wherein said inorganic lubricant is contained in the heat-sealing layer, according to claim 1 of the polyolefin-based laminate film. 3. The method according to claim 1, wherein the main component is polypropylene.
1 or 2 polyolefin-based laminated film. 4. The port according to claim 1, wherein
On the surface of the one surface layer of the polyolefin-based laminated film
Aluminum deposited film with aluminum deposited
M 5. The laminated polyolefin film according to claim 1.
Aluminum is deposited on the surface of the one surface layer of the
A polyethylene-based film layer on the deposition surface.
Biaxially oriented polypropylene on polyethylene film
Characterized in that a multi-layer film layer is laminated.
Olefin-based laminated film.