JP2000191803A - Adhesive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film excellent for use in food packaging or the like. SOLUTION: This film is obtd. from a resin compsn. comprising (A) 100 pts.wt. of a polypropylene resin, (B) 3-40 pts.wt. of an org. compd. having a viscosity of 3,000-90,000 mPa.s at 25 deg.C and a solubility, parameter of 7.0-9.0 cal/cc, and (C) 0.3-20 pts.wt. of an org. compd. having a viscosity of 20-2,000 mPa.s at 25 deg.C and a solubility parameter of 9.0-16.0 cal/cc, wherein the ratio of materials existing on the film surface as measured by the photoelectron spectroscopy is: A:(B+C)=85:15 to 30:70; and B:C=75:25 to 30:70.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive film used for food packaging and the like. More specifically, the present invention relates to a pressure-sensitive adhesive film excellent in feedability, transparency, heat resistance, food safety, and the like, in addition to the pressure-sensitive adhesiveness.

[0002]

2. Description of the Related Art Adhesive films are widely used for hermetically packaging foods and the like. In particular, in the spread of microwave ovens, microwave ovens are used to prevent drying during heating and prevent the flavor of food from being impaired. A wrap film for packaging in such an application is required to have adhesiveness to a container or adhesiveness between films.

[0003] Conventionally, as a wrap film used for food packaging, a film mainly composed of polyvinylidene chloride, polyethylene and polyvinyl chloride is known. However, polyvinylidene chloride-based films have a disadvantage that shrinkage upon heating is large. Polyethylene-based films are in contact with oily substances (for example, meat or tempura) and when the temperature becomes high, the film becomes There is a disadvantage that the film is melted. Further, the polyvinyl chloride film has a problem that a whitening phenomenon occurs when the film is brought into contact with boiling hot water. Further, the chlorine-based film has a problem that toxic gas is generated at the time of incineration treatment, and is not sufficiently environmentally friendly.
In order to solve such a problem, a large number of adhesive films made of a polypropylene resin have been proposed (for example,
JP-A-4-328144, JP-A-6-238748
JP-A-7-3089, JP-A-10-212361
Issue).

[0004]

However, the pressure-sensitive adhesive film made of such a polypropylene-based resin is still inferior in the pressure-sensitive adhesiveness as compared with a film that has been practically used in the past, or has an adhesiveness, a drawability, or the like. Each performance such as transparency and heat resistance cannot be achieved in a well-balanced manner, and has not yet been sufficiently commercialized.

[0005]

Means for Solving the Problems The present inventors diligently studied a method for imparting a practically sufficient tackiness as a wrap film for packaging to a film made of a polypropylene resin, and as a result, a predetermined viscosity and a polypropylene resin were obtained. The present inventors have found that an optimal adhesive film as a packaging wrap film can be obtained from a polypropylene resin containing at least two or more types of additives having a predetermined compatibility with the present invention, and completed the present invention.

That is, the gist of the present invention is that (A) 100 parts by weight of a polypropylene resin, (B) an organic resin having a viscosity at 25 ° C. of 3000 to 90000 mPa · s and a solubility parameter of 7.0 to 9.0 cal / cc. Compounds 3-4
0 parts by weight, and (C) a viscosity at 25 ° C of 20 to 20.
00 mPa · s, solubility parameter is 9.0-16.
A film obtained from a resin composition comprising 0.3 to 20 parts by weight of an organic compound having 0 cal / cc,
The abundance ratio on the film surface measured by photoelectron spectroscopy is A: (B + C) = 85: 15 to 30: 7
0 and B: C = 75: 25 to 30:70.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The pressure-sensitive adhesive film of the present invention can be obtained using the polypropylene resin composition comprising the components A, B, and C as a raw material. Further, this adhesive film can be used as an adhesive laminated film having a surface layer and another resin as an intermediate layer.

The type of the polypropylene resin as the component A is not particularly limited, and may be a propylene homopolymer or a copolymer of propylene with a small amount of another copolymer component (eg, ethylene, butene, etc.). Isotactic polypropylene as propylene homopolymer,
Syndiotactic polypropylene or atactic polypropylene can be mentioned, but isotactic polypropylene is preferable for film formation. The copolymer of polypropylene and another copolymer component such as ethylene may be a random copolymer or a block copolymer.

The physical properties of the above polypropylene resin may be appropriately selected according to various uses and conditions, and the melt flow rate (MFR) is usually 0.5 to 30 g / 10 min.
Preferably it is 2 to 15 g / 10 min, and the density is 0.89
It is preferably from 0.91 g / cm3 to 0.91 g / cm3. The melt flow rate is 230 in accordance with JIS K6758.
Means a value measured at 2.degree.

The viscosity of the component B (25 ° C.) is 3000 to 90
Organic compounds having a solubility parameter (25 ° C.) of 7.0 to 9.0 cal / cc have high compatibility with polypropylene and are highly viscous liquid additives at room temperature. The excess that could not be compatibilized oozes slightly on the surface of the film,
When a slight pressure is applied to the film, a so-called adhesive property is provided so that an object adheres. Note that
The bleeding of the components onto the film surface in this way is called bleeding. The viscosity of component B (25 ° C.) is 3000
90000 mPa · s, preferably 3000 to 3000
Although it is 0 mPa · s, if the viscosity is less than 3000 Pa · s, it is not preferable because the adhesive force to the object is insufficient. On the other hand, if the viscosity exceeds 90000 mPa · s, it is not preferable because it exhibits an unnecessarily high adhesive force and is hardly peeled off after being brought into close contact with the object, and the transparency tends to decrease. On the other hand, if the solubility parameter is out of the above range, the compatibility with the polypropylene becomes poor, so that the B component excessively bleeds on the film surface, which is not preferable.

The amount of the component B is 3 to 40 parts by weight, preferably 5 to 25 parts by weight, per 100 parts by weight of the polypropylene resin as the component A. When the amount is less than 3 parts by weight, sufficient tackiness is not exhibited. On the other hand, when the amount exceeds 40 parts by weight, stickiness due to a large amount of bleeding occurs and heat resistance tends to decrease, which is not preferable. The type of the organic compound corresponding to the component B is not particularly limited, and examples thereof include polybutene, polyisobutylene, and the like included in the above physical property ranges.

The viscosity (25 ° C.) of the component C is from 20 to 2000.
mPa · s, solubility parameter (25 ° C.) 9.0 to 9.0
An organic compound of 16.0 cal / cc can further increase the adhesiveness of the film when used in combination with the component (B). The component C imparts physical properties such that an object can be easily attached without applying much pressure, and is easily bleeding on the film surface. The C component has low compatibility with polypropylene and has sufficient fluidity to increase the contact area with the adherend with a small load.

[0013] In addition, a wrap film is usually produced as a product wound on a paper core, and it is also an important quality item that the film can be easily unwound at the time of use. Calling. With respect to this dispensing property, if only the component B is used, the adhesive property increases but the dispensing property deteriorates. However, by using the component C together, it is possible to further increase the adhesive property while improving the dispensing property. it can.

The viscosity of the component C (25 ° C.) is from 20 to 2000.
mPa · s, preferably 20 to 2000 mPa · s, 2
It is 0 to 1200 mPa · s. 20-1200 viscosity
When the viscosity is less than mPa · s, the adhesion to the object is insufficient, which is not preferable. On the other hand, if the viscosity exceeds 2,000 mPa · s, there is not enough fluidity to increase the contact area with the adherend, so that the effects of improving the adhesiveness and the dispensing property are small, which is not preferable. In addition, it is also desirable that the component C has an antifogging function. The amount of the component C is 0.3 to 20 parts by weight, preferably 2 to 11 parts by weight, based on 100 parts by weight of the polypropylene resin of the component A. When the amount is less than 0.3 part by weight, sufficient tackiness is not exhibited. On the other hand, when the amount exceeds 20 parts by weight, stickiness due to a large amount of bleeding occurs and heat resistance is lowered, which is not preferable. The type of the organic compound corresponding to the component C is not particularly limited, and examples thereof include glycerin fatty acid esters, polyglycerin fatty acid esters, and sorbitan fatty acid esters which are included in the above-mentioned physical property ranges.

In the polypropylene resin composition comprising the above components A, B, and C, other components may be contained as long as the properties of the composition are not impaired.
So-called heat stabilizers, weather stabilizers, lubricants, antistatic agents,
Additives such as a nucleating agent, a filler, a pigment, a dye, a flame retardant, and an antiblocking agent may be contained in an amount of about 0.005 to 3% by weight.

The pressure-sensitive adhesive film of the present invention is obtained by molding the polypropylene resin composition having the above composition by an extrusion molding method or the like. As the extrusion molding, a T-die molding method and a water-cooled inflation molding method are usually employed. That is, by quenching the melt-extruded resin sheet by the above-mentioned molding method, a film having more excellent transparency can be obtained as compared with an air-cooled inflation molding method which is usually often used. Further, in the pressure-sensitive adhesive film, uniaxial stretching or biaxial stretching may be performed to improve cutability. The thickness of such an adhesive stretched film is usually 40 μm or less, preferably 2 to 30 μm.
μm, particularly preferably 5 to 20 μm. If the thickness of the film is larger than 40 μm, the tear strength at the time of cutting the film becomes too large, which is not very suitable for use as a wrap film.

The pressure-sensitive adhesive film of the present invention further comprises:
Photoelectron spectroscopy (X-ray Photo electron Spectoroscopy,
The abundance ratio on the film surface measured by XPS is as follows: polypropylene (A): additive (B + C) = 85:
15 to 30:70, and B: C = 75: 25 to 30:70. If the abundance ratio is out of the above range, it is not preferable because an appropriate adhesive force is not exhibited as an adhesive film. The abundance ratio does not always fall within the above range as long as the amount of additive components B and C is within the above range. For example, after forming into a film,
For wrap film applications, it is commercialized as wound on a paper core, and the surface abundance ratio is within the specified range at normal temperature atmosphere, but it may be out of the specified range if left in a high temperature atmosphere is there. That is, it is necessary that the abundance ratio of the additive on the film surface when the film is used is within the above range.

On the other hand, the pressure-sensitive adhesive film of the present invention can be a pressure-sensitive adhesive laminated film having a pressure-sensitive adhesive film portion as a surface layer and another heat-resistant resin as a resin as an intermediate layer. As this intermediate layer, any of polyamide resin, ethylene-vinyl alcohol copolymer resin, 4-methyl-pentene resin, and polyester resin is particularly preferable. In such an adhesive adhesive film, the adhesive layer is usually used as a surface layer, and another resin is used as an intermediate layer. Further, the adhesive layer and the intermediate layer may be directly laminated, or may be laminated with an adhesive layer of an adhesive interposed therebetween. When the above-mentioned adhesive laminated film is obtained, it is preferable to carry out the same molding method by a co-extrusion molding method.

The total thickness of the adhesive laminated film is preferably 40 μm or less, and the thickness of the intermediate layer is 10 to 90%, preferably 10 to 50% of the total thickness of the film. If the thickness of the central layer is smaller than 10% of the whole, the characteristics of the resin used as the central layer are hardly exhibited. For example, when the heat resistance is less than 10%, it becomes difficult to improve the heat resistance.
%, The thickness of the polypropylene layer becomes thin, and it becomes difficult to exhibit adhesiveness. In addition, even in the case of an adhesive laminated film, the definition of the abundance ratio on the film surface measured by the photoelectron spectroscopy described above is applied, but the target surface is not a contact surface between the intermediate layer and the adhesive layer, The opposite outer surface.

[0020]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples unless it exceeds the gist thereof. The measurement in the examples was performed by the following method.

(1) Film surface abundance ratio The valence band spectrum of each compound present on the film surface was measured using a photoelectron spectrometer under the following conditions. The ratio of each component was calculated by applying fitting calculation by the least square method using the reference spectrum to the spectrum.・ X-ray condition Mg8kev30mA ・ Measurement range 0-35eV ・ Measurement area 6mmφ

(2) Peel strength Lightly superimpose two films, and apply 25
mmφ, linear pressure 0.3kg / c with roll of 150mm width
m, three times, and the force required when the two films were peeled off within 5 minutes and when peeled in the 180 ° direction were measured with an instro type tensile tester. Table 1 shows the measurement conditions. In this test, the larger the value of the shear peel strength, the better the adhesiveness, and the smaller the value of 180 ° peel strength, the better the dispensing property.

[0023]

[Table 1]

(3) Transparency The transparency was measured using a transparency measuring device manufactured by Murakami Color Research Laboratory. There are three types of measured values: a MAX value, a MIN value, and an AVE value. The measured value is indicated by the MAX value that most closely corresponds to the visual perception.

(4) Heat-resistant temperature A paper is placed on top and bottom 25 mm of a strip film sample having a width of 30 mm and a length of 140 mm, and a weight of 10 g is lowered. The maximum ambient temperature that could not be cut in one hour was measured at 10 ° C intervals.

Examples 1 to 6, Comparative Examples 1, 2, 4 to 7,
9, 10 (A) Ethylene-propylene random copolymer (ethylene content 2.5%, Novatec PP MG3 manufactured by Nippon Polychem Co., Ltd.) as a polypropylene resin, polybutene shown in Table 2 as a component (B), (C) After mixing a polypropylene resin composition using a mixture of diglycerin monooleate and diacetyl monolauryl glycerin shown in Table 2 as a component with a blender, a diameter of 30 was obtained.
The mixture was pelletized at 220 ° C. using a twin-screw extruder of 2 mm.
The pellets were converted to 25 using a 450 mm wide T-die molding machine.
Extrusion was performed at 0 ° C. to obtain a film having a thickness of 10 μm. Table 2 shows the evaluation results of this film. The parts by weight in the table are the values when (A) the polypropylene resin is 100.

Example 7 The polypropylene resin composition of Example 1 was used for the surface layer, nylon-6 (manufactured by Mitsubishi Engineering-Plastics Co., Ltd., Novamid 1020) for the intermediate layer, and the modified polyolefin (manufactured by Mitsubishi Chemical Corporation) for the adhesive layer. , Modick AP196
As P), three types of extruders were simultaneously extruded from three extruders at a die temperature of 260 ° C. using a 450 mm wide three-layer, five-layer co-extrusion T-die molding machine, and were composed of surface layer / adhesive layer / intermediate layer / adhesive layer / surface layer Seed 5-layer film (thickness 30 μm, layer ratio 3: 1:
2: 1: 3). Next, the film was stretched 3.0 times in the machine direction by roll stretching at a preheating temperature of 60 ° C. and a heat setting temperature of 110 ° C. to obtain a film having a thickness of 10 μm. Table 2 shows the evaluation results of this film.

Comparative Example 3 The procedure of Example 1 was repeated except that diglycerin monooleate shown in Table 2 was used as the component (B). Table 2 shows the results. Comparative example 8 It carried out similarly to Example 1 except having used polybutene shown in Table 2 as (C) component. Table 2 shows the results.

[0029]

[Table 2]

The values measured in the above Examples and Comparative Examples are as follows. From the viewpoint of practicality when used as a wrap film for packaging, the adhesive strength has a shear peel strength of 0.1.
It is considered preferable that the peel strength is 40 kg / cm ² or more, the 180 ° peel strength is 4.0 g / 50 mm or less, the transparency is 80% or more, and the heat resistance temperature is 140 ° C. or more.

[0031]

According to the present invention, a pressure-sensitive adhesive film which maintains excellent heat resistance and food safety inherent to a polypropylene-based resin, and also has good pressure-sensitive adhesiveness, feedability and transparency. Is provided. This adhesive film is
It is not necessary to contain harmful additives and is particularly suitable for wrap films for food packaging.

Continued on the front page F-term (reference) 4F071 AA15X AA20 AA20X AA21 AC10 AE22 AF30 AF45 AF53 AF58 AH04 BC01 BC02 4F100 AH00A AH00C AK02B AK07A AK07C AK09 AK41B AK46B AK64 AK69J13 BA03 BA06B13 J06 BA10 YY00A YY00C

Claims (2)

[Claims] (A) 100 parts by weight of a polypropylene resin, and (B) a viscosity at 25 ° C. of 3000 to 90000.
mPa · s, solubility parameter is 7.0 to 9.0 ca
3 to 40 parts by weight of an organic compound of 1 / cc, and (C)
A film obtained from a resin composition comprising 0.3 to 20 parts by weight of an organic compound having a viscosity at 25 ° C of 20 to 2000 mPa · s and a solubility parameter of 9.0 to 16.0 cal / cc. The abundance ratio on the film surface measured by the following formula is A: (B + C) =
85:15 to 30:70, and B: C = 75: 25
To 30:70. 2. A method according to claim 1, wherein both sides of an intermediate layer comprising a polyamide resin, an ethylene-vinyl alcohol copolymer resin, a 4-methyl-pentene resin, or a polyester resin are coated with (A)
100 parts by weight of a polypropylene resin, (B) 3 to 40 parts by weight of an organic compound having a viscosity at 25 ° C of 3000 to 90000 mPa · s and a solubility parameter of 7.0 to 9.0 cal / cc, and (C) at 25 ° C. Viscosity is 20 to 2000 mPa · s, solubility parameter is 9.
Organic compound 0.3 to 2 at 0 to 16.0 cal / cc
An adhesive layer obtained from a resin composition comprising 0 parts by weight is provided, and the abundance ratio on the outer surface of the adhesive layer measured by photoelectron spectroscopy is A: (B + C) = 85: 15 to 30:70. And B: C = 75: 25 to 30: 7
0. An adhesive laminated film characterized by being 0.