JPH0661898B2 - Evaporated film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vapor-deposited film applied to general packaging materials, various industrial materials and the like.

[Prior Art] Conventionally, a film obtained by subjecting a polypropylene biaxially stretched film to a surface treatment and vapor-depositing a metal such as aluminum has been widely used for general packaging applications and the like.

[Problems to be Solved by the Invention] However, the vapor-deposited film obtained by the conventional method, that is, only the surface treatment, has insufficient vapor-deposition adhesive strength, and the vapor-deposited film is easily scratched and peeled due to abrasion. If the vapor deposition adhesive strength is not sufficient, the vapor deposition film may be peeled off by blocking under high temperature and high humidity (especially in summer).

Especially with vapor-deposited films that have excellent gloss and reflectivity,
Such a phenomenon was more prominent.

On the other hand, as disclosed in JP-B-58-50592, it is known to use a composite film of a polypropylene film and an ethylene-propylene copolymer so that metal deposition can be performed without anchor coating. However, this technique has a drawback in that a metal-deposited film having excellent gloss cannot be obtained even if metal deposition can be performed without anchor coating.

In view of such circumstances, the object of the present invention is that the adhesive strength of the vapor deposition film is tough, and in the manufacturing process or after being a product, sufficiently wear and abrasion resistant, and excellent processing characteristics,
It is intended to provide a vapor-deposited film having gloss and reflectivity.

[Means for Solving Problems] The present invention comprises a polypropylene biaxial film (A), a film (B) made of an ethylene-propylene random copolymer having an ethylene component of 1 to 15 wt%, and a metal vapor deposition layer (C). (A), (B), and (C) are laminated in this order, the film (A) has a surface roughness R.
a is 0.15 μm or more, the film (B) has an orientation coefficient in the length direction and the width direction of 7.0 or less, and is 20% by weight.
The following polypropylene is added or a nucleating agent is added and the time to the peak of the DSC isothermal crystallization curve at 120 ° C. is 9 minutes or less, and the metal vapor deposition layer (C) has a surface glossiness of 600 or more. It is a vapor deposition film.

Biaxially oriented polypropylene (hereinafter referred to as "OP
The film (A) is a biaxially stretched film stretched by a well-known stretching method such as simultaneous biaxial or sequential biaxial, and is a polypropylene homopolymer usually used as polypropylene. And ethylene in it,
The homopolymer or copolymer of α-olefin represented by Buden-1 is blended with polypropylene within a range not exceeding 50% by weight. OP
The thickness of the P film is not particularly limited, but is 3 to
120μ is preferable.

The surface roughness Ra of the OPP film (A) should be 0.15 μ or more, preferably 0.2 to 2.0 μ.
If Ra is less than 0.15 μ, blocking is likely to occur,
When rewinding from a metal vapor deposition film wound into a roll, the vapor deposition film is easily stripped off. Further, since the slipperiness is deteriorated, wrinkles are liable to be formed during processing, and the processing speed must be kept low. The surface roughness R
“A” means the center line average roughness (cutoff value 0.25 mm), which is based on JIS B 0601.

As a method for roughening the surface of the OPP film (A), any method such as an embossing method, a method of adding inorganic particles, or a method of utilizing a difference in melting point between α crystal and β crystal may be used. Also,
A roughened resin film layer may be provided on the surface of the OPP film (A). As the surface-roughened resin film layer, a thermoplastic resin containing inorganic particles, one obtained by laminating a low melting point resin having excellent embossability by coextrusion, or a polyester containing an inorganic particle dissolved in an organic solvent, a polyamide And the like.

The ethylene-propylene random copolymer (B) having an ethylene component of 1 to 15 wt% in the present invention (hereinafter referred to as "REP
The film consisting of "C" is a polymer in which ethylene is randomly copolymerized with propylene, and the ethylene content is 1 to 15 wt%, preferably 2 to 10 wt%. In the REPC film, α-polyolefin such as polyethylene and polypropylene, ethylene-propylene block copolymer, etc. may be blended in the range of 30 wt% or less. When polyethylene or the like is blended, the ethylene component means all ethylene components including polyethylene.

When the ethylene component is less than 1 wt%, it is difficult to obtain the adhesive strength of the vapor deposition film according to the present invention, and the ethylene component is 15% by weight.
If it exceeds wt%, it is difficult to maintain the surface glossiness of the vapor deposition surface according to the present invention, or it is not possible to form a uniform composite during composite, and so-called laminate omission occurs.

Quantitative determination of the ethylene component is usually carried out by infrared absorption spectrum using 1170 cm ^-1 due to polypropylene and 715 to 725 cm ^-1 or 7 due to copolymerized ethylene.
It can be determined by the calibration curve method from the absorbance ratio of 30 to 735 cm ^-1 . The ethylene component referred to in the present invention can be identified by the presence or absence of absorption at 730 to 735 cm ^-1 in the infrared absorption spectrum.

Although it can be determined by the presence or absence of absorption at 715 to 725 cm ^-1 , this absorption band cannot be used when REPC is contained because this absorption disappears in REPC. The thickness of the layer having this composition is not particularly limited, but is preferably 20% or less of the thickness of the polypropylene film layer (A).

The orientation coefficient of the REPC film (B) of the present invention is
Both the length direction (abbreviated as MD) and the width direction (abbreviated as TD) must be 7.0 or less, preferably 2.5 or less in MD and 6.0 or less in TD. The orientation coefficient was calculated from the ATR spectrum using polarized light rays parallel to the plane of incidence. The outline of the measurement conditions is shown below.

Apparatus: FT-IR apparatus FTS-15E / D (DIGILAB INC.) Incident angle: 60 ° In the measured spectrum, bands attributable to ethylene and propylene are observed. Further, because of the measurement using polarized light, the band intensities attributed to π in MD and δ in TD of the film are strongly opposite to each other. The orientation coefficient was calculated as the integrated intensity ratio of the polypropylene peak 842 cm ⁻¹ (π) and 808 cm ⁻¹ (δ).

If the orientation coefficient exceeds 7.0, a satisfactory adhesion strength of the deposited film cannot be obtained. As a factor that determines this orientation coefficient, not only the draw ratio, but also the film temperature during drawing and the characteristics of the raw materials are important. That is, the orientation temperature of the REPC film (B) is remarkably increased by increasing the film temperature during stretching to the melting point of the laminated polymer (B) (generally 110 to 140 ° C. for ethylene-propylene copolymer or ethylene) as much as possible. descend. Therefore, in order to obtain the orientation coefficient of the present invention, the melting point of polypropylene used in the OPP film (A) (about 161 ° C. for crystalline polypropylene)
It is necessary to draw at a temperature close to the above, that is, a film temperature of 150 to 160 ° C. This requirement may be satisfied in the heating section for transverse stretching in the longitudinal and transverse biaxial stretching, and in the heating section for simultaneous biaxial stretching.

In addition, the REP may also differ depending on the raw material characteristics of the REPC film (B), particularly the melt index and the ethylene content ratio.
The degree of orientation of the C film (B) changes greatly. That is, in order to reduce the degree of orientation, it is preferable to increase the melt index and the ethylene component ratio.

The REPC forming the REPC film (B) is 120
The time to the peak of the DSC isothermal crystallization curve at 0 ° C must be 9 minutes or less, preferably 7 minutes or less, more preferably 5 minutes or less. If the time to the peak exceeds 9 minutes, the metal vapor deposition layer (C) having sufficient surface gloss cannot be obtained on the surface of the film (B) while maintaining the adhesive strength. In addition, the surface glossiness of the metal vapor deposition layer (C) depends on the surface glossiness of the REPC film (B), and it is improved by making the film temperature at the time of stretching as low as possible, but the orientation degree is also increased. It is difficult to maintain the value of the orientation coefficient. The surface glossiness of the film (B) depends on the crystallization process until the film discharged from the tenter is wound in the air while being cooled, and the higher the stretching temperature, the lower the surface glossiness. However, when the crystallization rate at 120 ° C. is increased, the size of the generated crystals becomes finer and the surface glossiness is improved regardless of the stretching temperature. In the present invention, 20% by weight or less of polypropylene or a nucleating agent needs to be added to the REPC film (B) in order to increase the crystallization rate at 120 ° C. That is, in order to increase the adhesive strength of the vapor deposition curtain, the stretching temperature is increased and the raw material characteristics are selected to set the orientation coefficient to 7.0.
Although it is necessary to make it below, the surface gloss of the film (B) surface decreases and the surface gloss of the metal vapor deposition surface decreases when the stretching temperature is increased. Therefore, 20% by weight or less of polypropylene is added to the REPC film (B) or a nucleating agent is added to accelerate crystallization, and the crystal size generated is miniaturized to reduce light scattering on the film surface. Thus, a film having excellent surface gloss can be obtained.

When polypropylene is blended, it is recommended that the orientation coefficient be 20 or less with respect to the REPC film (B).
It should be less than or equal to weight%.

Aluminum benzoate or the like is suitable as the nucleating agent, but the amount of the nucleating agent added is preferably about 0.1% by weight based on the REPC film (B).

The surface of the REPC film (B) should be activated by surface treatment such as corona discharge treatment, acid treatment, and flame treatment. At that time, in the nitrogen gas or the nitrogen-carbon dioxide mixed gas, the corona Discharge treatment is preferred.

The metal vapor deposition layer (C) is applied on the surface of the REPC film (B). The metal to be vapor-deposited is not particularly limited, but aluminum and zinc are usually preferably used. The vapor deposition method is also not particularly limited, and known methods such as electrothermal heating and melting vapor deposition method, ion beam vapor deposition method, sputtering method, or ion plating method can be used. The thickness of the vapor deposited film is preferably in the range of 100 to 5000Å.

The surface glossiness of the metal vapor deposition layer (C) is JIS-Z-8741.
It is represented by GS (60 °) based on Method 2,
The higher this value, the better the gloss.

The surface roughness Ra of the REPC film (B) is preferably 0.15 or less so that the surface glossiness of the metal vapor deposition layer (C) is 600 or more. Such a surface gloss can be obtained by keeping the ethylene component and the crystallization rate within the above range.

The vapor-deposited film of the present invention includes OPP film (A), RE
A PC film (B) metal vapor deposition layer (C) is provided, and the laminated structure is (A) / (B) / (C).

Next, a method for producing the film of the present invention will be described.
Polypropylene to which inorganic particles are added and REPC are simultaneously melt extruded into a sheet, cooled and solidified, and further heated and stretched in the longitudinal and transverse directions. The lamination of REPC is not limited to the above-mentioned co-pressing, and may be before uniaxial stretching, before biaxial stretching or after. As a method of roughening, instead of adding inorganic particles to polypropylene, instead of adding inorganic particles before or after stretching,
It may be embossed before or after stretching, or polypropylene, polypropylene, and REPC containing inorganic particles may be coextruded to form a three-layer film.

In this manner, the REPC film (B) surface of the obtained film is subjected to corona discharge treatment, and aluminum or the like is vapor-deposited on the surface by a vacuum vapor deposition device.

In the present invention, an antioxidant, a heat stabilizer, an ultraviolet absorber, a lubricant, a pigment, an antistatic agent or the like is usually added to either or both of the OPP film (A) and the REPC film (B), if necessary. It may be added within a range that does not impair the characteristics of the present invention.

[Evaluation Method, Measurement Method] The characteristics or effects of the present invention are based on the following criteria.

(1) Peak of DSC isothermal crystallization curve Using a differential scanning calorimeter Model DSC-2 manufactured by Perkin-Elmer, 5 mg sample was heated at 320 ° C./min at 280 ° C.
After heating up to 5 minutes and holding for 5 minutes, it is cooled at the same speed and an isothermal crystallization curve is taken at 120 ° C.

The peak is the inflection point of this curve.

It should be noted that the time until the peak is 120 during the cooling process of the sample.
It refers to the time from when the temperature reaches ° C to when the peak occurs.

(2) Crystallization temperature Using a differential scanning calorimeter Model DSC-2 manufactured by Perkin-Elmer, a 5 mg sample was heated to 280 ° C. at a temperature rising rate of 20 ° C./minute and held for 5 minutes, and then at the same speed. Cool and take the cooling curve. Crystallization temperature refers to the temperature at the inflection point of this curve.

(2) Blocking A sample film with a width of 3 cm and a length of 10 cm is overlapped over a length of 4 cm, and 3 kg is placed in an atmosphere of 40 ° C. and 85% RH.
After standing for 5 days under a load of 1, the force required for shear peeling is measured by a tensile tester. The smaller the number, the less blocking.

(3) Adhesion strength of vapor-deposited film A commercially available cellophane adhesive tape (manufactured by Nichiban Co., Ltd.) was attached to the vapor-deposited surface, and the adhesion area of the vapor-deposited metal after 180 ° peeling was evaluated based on the six grades (index) in Table 1. did.

(4) Glossiness GS (60 °) based on JIS-Z-8471 Method 2 is expressed in%, and the higher the value, the better the glossiness and the reflection.

[Embodiment] Next, the effect of the present invention will be described based on an embodiment.

Example 1 Commercially available polypropylene pellets (melt index at 230 ° C. 2 g / 10 minutes, isotacticity 97.3)
%) In which 7 wt% of silicon dioxide is added to one extruder, and REPC (melt index at 230 ° C. of 6.5 g / 10 min with 3 wt% of ethylene component and 0.1 wt% of aluminum benzoate as a nucleating agent). Was fed to another extruder and melt-extruded into a sheet at 270 ° C., which was wound around a cooling drum having a surface temperature of 45 ° C. to be cooled and solidified. This laminated sheet was stretched 4.5 times in the longitudinal direction while being heated to 125 ° C. Further, the film is guided to a stenter and stretched 9 times in the width direction at a stretching temperature of 160 ° C., then heat-treated at 160 ° C. while giving 5% relaxation in the width direction, and gradually cooled to a thickness of 20 μ (polypropylene substrate layer). 18 μ) laminated film was prepared. 1 on both sides of this laminated film
Corona discharge treatment with an electric energy amount of 000 to 6000 J / m ² was performed.

Set these films in a vacuum evaporation system and use RE
Aluminum was vapor-deposited on the PC surface so that the vapor-deposited film had a thickness of 600 Å to obtain a vapor-deposited film.

Comparative Example 1 A vapor deposition film was obtained in the same manner as in Example 1 except that the stretching temperature in the width direction was 145 ° C.

Comparative Example 2 A vapor-deposited film was obtained in the same manner as in Example 1 except that REPC containing no nucleating agent was used.

Comparative Example 3 The coextrusion raw material was a REPC containing 6% of an ethylene component (230 ° C.
Melt index 7.0g / 10min) and low density polyethylene (190 ℃ melt index 2.0g / 1
Example 1 in a 4: 1 blend of 0 minutes, density 0.925)
A vapor-deposited film was obtained in the same manner as in Example 1 except that the one to which a nucleating agent was added was used in the same manner as in.

Example 2 Instead of adding a nucleating agent to REPC in Example 1, polypropylene (melt index 3.5 at 230 ° C. 3.5
g / 10 min, isotacticity 98.0) 10 wt%
A vapor-deposited film was obtained in exactly the same manner as in Example 1 except that the blended product was used.

Comparative Example 4 A vapor-deposited film was obtained in exactly the same manner as in Example 1, except that polypropylene to which silicon dioxide was not added was used.

Table 2 summarizes the properties of these vapor-deposited films.

From the table, Examples 1 and 2 are films in which the adhesive strength of the deposited film is strong, have excellent metallic luster and reflectivity, and are easy to process without blocking. 7. The orientation coefficient of the present invention is 7.
When it exceeds 0 (Comparative Example 1), the adhesive strength of the deposited film is low.
When the nucleating agent was not added and the time to the peak of the isothermal crystallization curve exceeded 9 minutes (Comparative Example 2) and the ethylene component exceeded 15 wt% (Comparative Example 3), sufficient metallic luster Was not obtained or was frosted. Further, when the surface roughness of the non-deposited surface was less than 0.15 (Comparative Example 4), blocking was likely to occur, and wrinkles were likely to occur during higher-order processing.

[Advantages of the Invention] The following effects are obtained as a vapor-deposited film: (a) The vapor-deposited film has a strong adhesive strength and excellent abrasion resistance and abrasion resistance. Therefore, even if the vapor deposition surface is exposed on the surface, it can be sufficiently used.

(B) The metal vapor deposition surface has excellent gloss and reflectivity.

(C) The film has good slipperiness, blocking resistance,
Excellent high-order processing characteristics.

Such vapor-deposited films include general packaging materials, paper, laminated materials on metals, industrial materials such as heat insulating agents and wall agents, and high adhesive strength of tough vapor-deposited films such as labels and stickers and high metal vapor deposition surface. It can be widely used in fields requiring glossiness and reflectivity.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-58-1523 (JP, A) JP-A-59-5055 (JP, A) JP-B-58-50592 (JP, B2)

Claims (1)

[Claims] 1. A polypropylene biaxial film (A), a film (B) made of an ethylene-propylene random copolymer having an ethylene component of 1 to 15 wt%, and a metal vapor deposition layer (C) (A) and (B). , (C) are laminated in this order, the film (A) has a surface roughness Ra of 0.15 μm or more, and the film (B) has an orientation coefficient of 7.0 or less in both the length direction and the width direction. If 20% by weight or less of polypropylene is added or a nucleating agent is added, the time to the peak of the DSC isothermal crystallization curve at 120 ° C is 9 minutes or less, and the metal vapor deposition layer (C) has a surface glossiness. Of 600 or more.