JPH0227940B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a moisture-proof polypropylene film having a metal vapor-deposited layer having a low water vapor permeability, that is, an excellent water vapor barrier property. [Conventional technology and problems] Polypropylene is said to have excellent moisture resistance, but its water vapor transmission rate is 10 (g/m ² days/15μ).
2 (g/m ² days/15 μm) or less, preferably 1
(g/m ² days/15 μm) or less. For this reason, attempts have been made to provide a metal vapor deposited layer such as Al on a biaxially oriented polypropylene film (hereinafter abbreviated as OPF), but a thin metal vapor deposited layer of approximately 50 to 100 Å cannot provide high moisture resistance.
Providing a thick metal deposition layer of 200-1800 Å was considered. However, the film provided with such a metal vapor deposited layer had the following serious drawbacks. Because metal is deposited thickly on the OPF, the dimensions of some parts of the OPF change due to the heat of the deposited metal, resulting in poor flatness of the film. The adhesion between the vapor-deposited metal and OPF is weak, and the metal easily peels off even in a peel test using cellophane tape. For this reason, other materials such as other films, cloth, and paper cannot be laminated on top of the vapor-deposited metal. When the thickness of the deposited metal is greater than 500 Å, blocking occurs when the deposited surfaces come into contact with each other or when the deposited surface and the film surface come into contact with each other, making it virtually impossible to unroll the metal. The present invention solves the above-mentioned drawbacks, and provides a vapor-deposited metal that has high moisture resistance, has a strong adhesion force of the vapor-deposited metal, and does not block even when the metal-deposited surfaces come into contact with each other or the metal-deposited surface and the polypropylene film surface. The purpose is to provide a polypropylene film. [Means for Solving the Problems] The present invention provides that 100 parts by weight of polypropylene contains 1 of a resin selected from petroleum resins that do not substantially contain polar groups and terpene resins that do not substantially contain polar groups.
A metal vapor-deposited layer is provided on a polypropylene film containing 5 to 100 parts by weight, preferably 10 to 29 parts by weight, of at least 1 species, and the glass transition temperature of the polypropylene film is 10 to 50°C; At least on the metal-deposited side of the film, imino-type and/or amino-type nitrogen atoms are added to the surface layer up to 100 Å from the surface.
The present invention relates to a polypropylene film having excellent water vapor barrier properties, characterized in that each film has two or more films. The polypropylene used in the film of the present invention is not particularly limited, but has an isotactic index () of 93% or more and an intrinsic viscosity [η] of 0.8 to 4 (dl/g) as measured in tetralin. ,
In particular, a range of 1.0 to 2.2 (dl/g) is desirable.
A second component other than propylene, such as ethylene, butene, hexene, maleic anhydride, etc., may be copolymerized in random, block or graft copolymerization, but a homopolymer is preferred from the perspective of the present invention. Note that polypropylene may contain known additives such as crystal nucleating agents, antioxidants, heat stabilizers, slip agents, antistatic agents, antiblocking agents, fillers, viscosity modifiers, and color inhibitors. good. Petroleum resins that do not substantially contain polar groups include hydroxyl groups (-OH), carboxyl groups (-COOH), halogen groups (-X), sulfonic groups (-SO ₃ Y, but
Y is H, Na, 1/2Mg, etc.) and modified products thereof. Petroleum resins without polar groups,
That is, it is a resin whose main raw material is a cyclopentadiene-based hydrocarbon made directly from a petroleum-based unsaturated hydrocarbon, or a higher olefin-based hydrocarbon. Furthermore, the glass transition temperature (hereinafter abbreviated as Tg) of the petroleum resin is preferably 50°C or higher, preferably 76°C or higher for the polypropylene film of the present invention. Note that the upper limit of Tg is not particularly limited, but is usually about 120°C or less. Further, it is particularly preferable that the polypropylene film of the present invention is a hydrogenated petroleum resin in which hydrogen is added to the petroleum resin so that the hydrogenation rate is 80% or more, preferably 95% or more. As a typical resin, a high Tg fully hydrogenated alicyclic petroleum resin such as polydicyclopentadiene having a Tg of 76° C. or higher and a hydrogenation rate of 95% or higher is particularly suitable for the present invention. In addition, terpene resin that does not substantially contain polar groups refers to terpene resin that does not have polar groups that are composed of hydroxyl groups, aldehyde groups, ketone groups, carboxyl groups, halogen groups, sulfonic groups, etc., and modified products thereof. , that is, hydrocarbons with a composition of (C ₅ H ₈ ) _o and modified compounds derived therefrom. n is a natural number of about 2 to 20. Terpene resins are also sometimes called terpenoids. Typical compound names include pinene, dipentene, carene, myrcene, ocimene, limonene, terpinolene, terpinene, sabinene, tricyclene, bisabolene, zingiberene, santarene, campholene, mylene, and totalene, and in the case of the film of the present invention. , hydrogen is added, and the hydrogenation rate is 80% or more, preferably
It is desirable that the content be 90% or more, and hydrogenated β-pinene, hydrogenated dipentene, etc. are particularly preferred. In the case of the present invention, it is important to use a hydrogenated resin as described above, and the bromine number is 10 or less, preferably 5.
The number below is more preferably 1 or less. The polypropylene film of the present invention is a film in which 100 parts by weight of the polypropylene is mixed with 5 to 100 parts by weight, preferably 10 to 29 parts by weight of one or more of the petroleum resins or terpene resins that do not contain polar groups. The film has a glass transition temperature Tg of 10 to 50°C, preferably 20 to 40°C, and at least the metal-deposited side of the film has an imino-type and/or amino-type surface layer up to 100 Å from the surface. 2 nitrogen atoms per 100 carbon atoms
It has more than one. If the amount of the above-mentioned resin containing no polar groups is 100 parts by weight or more, preferably 29 parts by weight or more, the mechanical, thermal, and chemical properties of the film will not only be poor, but even the polypropylene film of the present invention will have poor mechanical, thermal, and chemical properties. Even if the surface layer is specially treated, the above-mentioned mixed resin bleeds out onto the film surface, worsening the adhesion, especially the adhesion to vapor-deposited metals, transparency, and appearance, and also impairs the permeability of oils such as vegetable oil and mineral oil. This causes serious problems such as oil seeping onto the film surface and printing ink on the film surface eluting, resulting in poor appearance. In addition, when the amount of the resin mixed is less than 5 parts by weight, preferably less than 10 parts by weight, the glass transition temperature
Regardless of the Tg value, the presence of metal vapor deposition hardly improves the water vapor barrier properties. As described above, the effects of the present invention are particularly significant when the amount added is as small as 10 to 29 parts by weight. In addition, if the Tg value is less than 10°C, preferably less than 20°C, even if the metal is deposited to the upper limit thickness at which the film does not deform, the water vapor permeability, which is the objective of the present invention, will be 2 (g/m ² days/ 15μm) or less, preferably 1
(g/m ² days/15μm) or less, and
No improvement in mechanical properties was observed either. On the other hand, if the Tg value exceeds 50°C, preferably 40°C, the mechanical properties of the polypropylene film of the present invention will be significantly deteriorated, and the vapor deposition and
Problems occur during processes such as lamination and printing. In addition, the polypropylene film is subjected to a special surface treatment, and at least 2 or more, preferably 4 or more imino-type and/or amino-type nitrogen atoms are added per 100 carbon atoms in the surface layer at 100 Å from the surface of at least one side. Must have. this is,
Although the film of the present invention contains petroleum resin or terpene resin, it not only has excellent oil resistance, adhesion/printability, bleed-out prevention property, and surface hardening property, but also has excellent oil resistance, adhesiveness/printability, bleed-out prevention property, and surface hardening property. This is because it is necessary to provide water vapor barrier properties that are better than those provided by water. Of course, in the known corona discharge treatment in air where the number of nitrogen atoms per 100 carbon atoms is less than 2, the excellent moisture resistance, adhesion, printability, blocking resistance, etc. that are the objectives of the present invention cannot be achieved. cannot be granted. The upper limit of the number of nitrogen atoms per 100 carbon atoms (hereinafter abbreviated as Nc) is not particularly limited, but is preferably 20 or less,
More preferably 15 or less. In the case of the polypropylene film of the present invention, the molecular chains may or may not be oriented, but it is possible to increase the Tg value by reducing the amount added,
Furthermore, from the viewpoint of mechanical properties, optical properties, thermal properties, etc., it is preferable that the molecular chains are oriented. In particular, it must be biaxially oriented and balanced within the film plane, that is, the birefringence is an absolute value.
It is desirable that it be 0.025 or less, preferably 0.015 or less. In addition, the value obtained by subtracting the refractive index in the thickness direction from 1/2 of the sum of the refractive index in the longitudinal direction and the refractive index in the lateral direction, which is a guideline for film surface orientation, is in the range of 0.006 to 0.012. This is preferable in terms of cleavage and oil resistance. Furthermore, the polypropylene film of the present invention
It is desirable that the degree of crystallinity is 50% or more, preferably 60 to 80%, and the thickness is 0.5 to 1000 μm, preferably 4 to 250 μm, and more preferably 8 to 60 μm.
It is desirable to have a range of . As described above, the polypropylene film of the present invention is made by mixing polypropylene with one or more resins selected from petroleum resins that do not contain polar groups and terpene resins that do not contain polar groups. If a resin is added, the amount should be less than 30 parts, preferably less than 20 parts. Other resins include polyolefins other than polypropylene, petroleum resins containing polar groups, and terpene resins containing polar groups. The metal vapor deposition layer of the present invention is a metal layer formed by a known metal vapor deposition method, such as a vacuum vapor deposition method or a sputtering method. The metal in this layer may be a single substance or an alloy of Al, Zn, Ni, Cr, Co, Fe, Au, Pa, etc.
Al, Zn, and Ni are preferred. Further, the thickness of the metal vapor deposition layer is not particularly limited, but it is preferably 100 to 2000 Å, particularly 200 to 1000 Å per side of the film. The moisture-proof film of the present invention is obtained by forming a metal vapor deposited layer on the surface of the polypropylene film of the present invention having a specific value of Nc, and the vapor deposited layer may be formed on one side of the film, or on both sides. It may be. The moisture-proof film of the present invention is suitable for applications where it is desired to avoid the transmission of water vapor, especially when the water vapor transmission rate is 2 (g/m ² days/
15 μm) or less, such as packaging for pharmaceuticals, foods, industrial products, etc. In addition, in order to impart heat-sealing properties to the moisture-proof polypropylene film of the present invention, other polymers such as polypropylene and polyethylene may be laminated, and in particular, polypropylene, ethylene-propylene copolymers, ionomers, etc. preferable. Next, a method for manufacturing the moisture-proof film of the present invention will be explained. The above-mentioned specific petroleum resin or terpene resin is added to polypropylene, melted at a resin temperature not exceeding 240°C, preferably at a maximum temperature of 180 to 220°C, mixed uniformly, and then discharged from a nozzle,
An unstretched film is obtained by casting on a cooling drum. In addition, at this time, the resin temperature is 240℃, preferably
If the temperature exceeds 220°C, not only will it not be possible to obtain a film with the excellent properties aimed at by the present invention, but the resin will thermally decompose or scatter. Further, the surface temperature of the cooling drum varies depending on the relationship with subsequent steps, but it is preferably in the range of 60 to 120°C, preferably 95 to 110°C. Subsequently, the cast film described above can be made into an oriented film by uniaxially, biaxially, or multiaxially oriented, or heat-treated to bring the Tg within a specific range. In this case, any known method can be used to provide orientation, such as roll stretching, rolling, tenter stretching, disk stretching, belt stretching, and combinations thereof. At this time, it is necessary to orient so that the Tg value falls within the above specified range. For example, in the case of sequential biaxial stretching, the initial longitudinal stretching ratio is 6 to 10.
The transverse stretching ratio is preferably about 6 to 12 times. Furthermore, the above film is subjected to corona discharge treatment or plasma treatment in the presence of carbon dioxide gas, nitrogen gas, etc. and in an atmosphere substantially free of oxygen, so that the imino type and/or amino type is formed in the extreme surface layer up to 100 Å from the surface. This introduces nitrogen atoms. As a typical surface treatment method, for example,
Essentially nitrogen N ₂ as shown in No. 30854 etc.
and carbon dioxide CO ₂ mixed gas (N ₂ /CO ₂ = 100/
0 to 50/50 volume ratio) atmosphere, and oxygen concentration
Corona discharge treatment is performed in an atmosphere of 0.1vol% or less.
Alternatively, methods of chemically modifying the film surface by placing various gases in a plasma state, such as JP-A-59-
There are issues such as No. 98140. A metal layer is formed on the surface of the polypropylene film of the present invention having two or more Nc values by a known vapor deposition method to obtain the moisture-proof film of the present invention. [Function] Although the function of the present invention has not been clearly elucidated, as mentioned above, a specific resin is added to polypropylene to form a polypropylene film having a specific Tg, and the surface is further subjected to a special surface treatment. By forming a layer in which specific atoms are bonded on the film surface, and forming a metal vapor deposition layer on top of that layer, the above layer exists like a uniform barrier film on the surface layer like the film surface. It is thought that this increases the adhesion of the vapor-deposited metal. [Effects of the Invention] The present invention mixes polypropylene with a specific resin, increases the glass transition temperature Tg of 10 to 50°C, which is much higher than the Tg of ordinary polypropylene (0°C), and Since specific atoms are added to the extreme surface layer of the mixed film and a metal vapor deposition layer is provided on that surface, the following excellent effects are achieved. That is, (1) It exhibits excellent barrier properties with a water vapor permeability of 2 (g/m ² days/15 μm) or less. (2) Since the organic compound added as an additive to the polypropylene film of the present invention does not substantially bleed out onto the film surface even after surface activation treatment, strong adhesion to the deposited metal can be obtained. (3) There is excellent slipperiness between vapor-deposited metal surfaces or between vapor-deposited metal surfaces and other materials, and blocking does not occur. (4) Excellent oil resistance and cleavage resistance, making it easy to print and
It has excellent lamination suitability and is an excellent gas barrier material for multilayer laminated packaging of oily products. (5) Even after the polypropylene film of the present invention is oriented and left at room temperature, the film hardly shrinks over time. This not only eliminates the need for an aging step immediately after film formation, but also eliminates the tightening of the film on the roll, which significantly improves productivity. Next, definitions of terms used in the present invention and measurement methods will be explained. (1) Water vapor transmission rate is 40℃ according to JIS Z-0208.
The value is measured at 90% RH and is expressed in units of [g/ ^m2・day/film thickness]. However, if it has a vapor deposited layer like the moisture-proof film of the present invention, the film thickness includes the vapor deposited layer.) (2) Intrinsic viscosity [η] is measured in tetralin according to ASTM D 1601. It is expressed in dl/g. (3) For the isotactic index (), cut the sample film into approximately 1 cm square pieces, place them in a Soxhlet extractor, and extract with boiling methyl alcohol for 6 hours. Extracted sample at 60℃
Vacuum dry for 6 hours. Weight W (mg)
A sample of the sample was taken and put back into the Soxhlet extractor and extracted with boiling N-heptane for 6 hours. Next, this sample is taken out, thoroughly washed with acetone, dried under vacuum at 60°C for 6 hours, and then weighed. If its weight is W' (mg), the isotactic index is calculated by the following formula. Isotactic index (%) = 100 x W'/W (4) Glass transition temperature (Tg) was determined by measuring 10 mg of the sample using a scanning calorimeter DSC-type (manufactured by Perkin Elmer).
The thermograph was set to 40°C/min under a nitrogen flow, starting at -20°C, and the arithmetic mean value of the temperature at which the endothermic peak deviated from the baseline and the temperature at which it returned was calculated. Let the temperature at which the temperature rises be Tg. Of course, this method may be used even if the sample is a composite film. (5) Bromine number is measured according to JIS K-2543-1979. This refers to the number of grams of bromine added to unsaturated components in 100 grams of sample oil. (6) To determine the refractive index N, use an Abbe refractometer with Na-D rays as the light source, use methyl salicylate as the mounting liquid, change the direction of the polarizing plate in the eyepiece, and measure the refractive index in a specific direction using the total internal reflection method. Measured by (7) Imino type and/or amino type nitrogen atoms are directly bonded to the carbon atoms of the polypropylene polymer chain, and the amount thereof is measured using the ESCA method. ESCA is an abbreviation for soft X-ray excitation photoelectron spectroscopy, which determines the type and chemistry of elements near the surface of a sample from the spectra of photoelectrons ejected from atoms in sample compounds by soft X-ray irradiation. This is a method to analyze the bond state. In the ESCA method, photoelectron transmission ability is small for hydrocarbon-based polymeric substances, and ESCA measurements of such polymeric substances have the characteristic that relatively strong information can be obtained within 100 Å of the surface, particularly in the extreme surface layer. The amino-type and/or imino-type nitrogen referred to in the present invention is a bonded nitrogen identified by the ESCA method, and is represented by an amino group or an imino group.
1S orbital of bonded nitrogen (N _1s ) measured by ESCA
Spectral binding energy is 397.0~402.5eV
(hereinafter simply referred to as _amino type nitrogen and/or imino type nitrogen). Specifically, using an ESCA spectrometer EG-200 manufactured by Kokusai Electric Co., Ltd., the N _1s spectrum and C _1s spectrum of the treated surface of the treated film were measured, and the amino type and/or imino type of the N _1s spectrum was measured. The ratio of the integrated intensity of the peak corresponding to the binding energy of nitrogen and the integrated intensity of the C _1s spectrum was calculated. (8) The depth of the modified surface layer was measured using a transmission electron microscope model HU-12 manufactured by Hitachi, Ltd.
A cross section of the surface layer of the surface-treated film was observed using an osmic acid staining method. Osmic acid stains the modified layer, and the reductively bound osmium forms image contrast in an electron microscope, allowing the depth of the modified layer to be determined. (9) For adhesion, Al is deposited on the film to a thickness of approximately 600 Å using a Bergier type high vacuum evaporation device at a vacuum level of approximately 1×10 ⁻⁵ mmHg. and,
A cellophane adhesive tape (Nichiban's "Cello Tape" is used) is attached to the vapor-deposited surface, the cellophane tape is rapidly peeled off, and the state of peeling of the Al vapor-deposited film is evaluated. 〇: Peeling area of Al vapor deposited film is 90% or more △: 〃 is 50% or more and less than 90% ×: 〃 is less than 50% (10) Form into a bag, seal 10 c.c. of Nisshin Salad Oil (manufactured by Nisshin Oil Co., Ltd.) in the bag, and leave the bag in a constant temperature bath at 40°C to observe oil seepage. When oil seeps onto the surface of the film, the film's gloss changes suddenly and can be measured with the naked eye. ○: Exudation exceeds 30 days △: 1 to 30 days ×: Less than 1 day [Examples] Embodiments of the present invention will be described based on Examples. Examples 1, 2, Comparative Examples 1 to 3 As polypropylene, Mitsui "Noblen" JS1429 manufactured by Mitsui Toatsu Co., Ltd. (measured limiting viscosity in tetralin [η] = 2.25 dl/g, isotactic index = 98%), and as a specific hydrogenated petroleum resin, Etsuso Chemical Co., Ltd.'s "Escoretsu" 5320, whose main component is nonpolar polydicyclopentadiene, is used.
was used. A raw material made by uniformly blending 25 parts by weight of "Escolets" 5320 with 100 parts by weight of the polypropylene resin was supplied to an extruder, and the melting temperature was adjusted to 220 parts by weight.
After extrusion at 85°C, the film was cast onto a casting drum kept at 85°C to obtain an unstretched film. The film was immediately introduced into a hot-air oven-heated longitudinal stretching roll kept at 135°C, stretched 7 times in the longitudinal direction, and then stretched 10 times in the transverse direction in a tenter heated to 158°C. ℃ for 10 seconds,
Heat treatment was performed while allowing 5% relaxation in the lateral direction, and then corona discharge treatment was performed on one side of the film in various atmospheres to obtain a biaxially oriented polypropylene film with a thickness of 15 μm. Al was deposited on the corona discharge treated surface of the film thus obtained to a thickness of 500 Å under a vacuum of 10 ⁻⁴ mmHg, and the film was wound up. The thus obtained moisture-proof polypropylene film Tg,
Various properties such as Nc, moisture resistance, and adhesiveness were measured and shown in Table 1. From Table 1, even if the same A original fabric is used, its moisture resistance, i.e., depending on the method of surface treatment, that is, the value of Nc,
It can be seen that the water vapor permeability, the adhesion strength of the Al deposited film, and the blocking property differ greatly, and the value of Nc must be 2 or more. Furthermore, even if the value of Nc is 2 or more, it can be seen that the moisture proofing properties will be significantly inferior unless the original fabric is added with a specific petroleum resin. 【table】

Claims (1)

[Claims] 1 A polypropylene film in which 100 parts by weight of polypropylene is mixed with 5 to 100 parts by weight of one or more resins selected from petroleum resins that do not substantially contain polar groups and terpene resins that do not substantially contain polar groups, is mixed with metal. A vapor deposited layer is provided, and the glass transition temperature of the polypropylene film is 10 to 50°C.
A moisture-proofing polypropylene which is characterized in that at least the metal-deposited side of the polypropylene film has two or more imino-type and/or amino-type nitrogen atoms per 100 carbon atoms in the surface layer within 100 Å from the surface. film.