JPS5933307B2 - Packaging material with good adhesion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a packaging material with good adhesion, particularly a packaging material with excellent packaging properties for obtaining a package in which a single item or a set of items packaged once housed in a box or the like is tightly packaged. The purpose of the present invention is to provide a packaging material having the following properties.

Furthermore, the present invention has excellent low-temperature thermal adhesion properties, sliding smoothness in a wide temperature range, hot plate releasability, etc., which are required when packaging products using automatic packaging machines, and excellent transparency and gloss. The present invention relates to a packaging material for obtaining a close-fitting package having the following properties. In recent years, sophisticated demands have been placed on the exteriors of foods, tobacco, industrial goods, daily necessities, etc.

For example, in food packaging, in addition to the characteristics of the exterior material such as moisture resistance, aroma retention, insect repellency, and oxygen barrier properties, sealed packaging also prevents tearing, improves appearance, insufficient sealing of thermally bonded parts during packaging, and insufficient adhesive strength. Problems such as poor airtightness from folded parts due to wrinkles in packaging materials are becoming more important. Furthermore, the odor of packaging materials is also a hygiene problem, and efforts are being made in the industry to reduce residual solvents. On the other hand, as automatic packaging machines have become increasingly faster and more efficient, the following characteristics are required for use in automatic packaging machines. In other words, in addition to the low-temperature thermal adhesion, the sliding property between the packaging material and the metal guide of the automatic packaging machine, the separability and sliding property between the packaging material and the hot plate, and the sliding property between the packaging material and the automatic packaging machine. These include the ability to prevent scratches and the ability to automatically feed packaging materials to automatic packaging machines. However, this alone cannot be said to be a complete close-tight packaging, and a gap is created between the packaged item and the packaging film. For this reason, some external force may catch on the sagging portion of the film and cause it to tear, making it one step more effective in enhancing the appearance. Packaging materials with heat-sealing properties include a coating film manufactured by dissolving a low-melting point substance in an organic solvent and coating it on a base film, and a coating film manufactured by dissolving a low-melting point substance in an organic solvent and coating it on a base film, and a coating film manufactured by laminating a low-melting point polymer on a base film and applying the low-melting point substance to the heat-sealing surface. A laminated film in which the melting point polymerized laminated surface is facing upward, or a single film made of polypropylene mixed with a low molecular weight thermoplastic resin, etc., have been proposed.

However, the film obtained by the coating method has a weak sealing strength at high temperatures and is not only unsuitable for the sealed package of the present invention, but also tends to cause the heat-sealed portion to separate or move (slip) due to the shrinkage stress during the heat-shrinking treatment. This not only impairs tight packaging but also prevents a perfect package. This means that the cohesive force of the sealing polymer is weak due to the use of a relatively low molecular weight polymer that can be dissolved in a solvent.
Another disadvantage is that it is difficult to completely eliminate residual solvent on the coating surface. A film obtained by mixing a low melting point polymer with polypropylene or the like has poor low-temperature sealing properties and may have poor transparency. Furthermore, since the film is flexible, its stiffness and rigidity are low, and automatic feeding becomes unstable, making it difficult to continuously wrap the film using an automatic packaging machine. Furthermore, although films mixed with low-molecular-weight thermoplastic resins exhibit sealing strength even at low temperatures, they have the disadvantage that their strength decreases as they are heated, making it difficult to obtain packaging with excellent sealing. . This is because the film is at a high temperature immediately after heat sealing, so the sealing strength in this state is weak, making it difficult to seal tightly and to package tightly. A force method in which a low melting point polymer is laminated on a base film has also been attempted, but as with the case of mixing low melting point polymers, when performing sequential biaxial stretching, in many cases, during stretching with heated rolls, Fused to the roll. For this reason, cold stretching is practically necessary, and a transparent film cannot be obtained under such conditions. For example, Tokuko Sho 41-4338
As seen in the publication, stretching in a low-temperature, high-stress field produces a large number of boards inside the film, resulting in a film with pearl-like luster. In addition, there is also a force method in which the base film is stretched with a heated roller, a low melting point polymer is laminated on one or both sides, and then stretched again with a tenter. However, none of these materials has been found to allow for complete tight packaging, which is the first objective of the present invention. The packaging material of the present invention with good adhesion has the feature that it can be produced by a sequential biaxial stretching method with high productivity and high thickness accuracy. In response to these demands, we have arrived at the present invention as a result of intensive research in order to provide a sealed package on the market.

That is, the present invention contains 5 to 70% by weight of the following component A and 5 to 70% by weight of the following component B.
95 to 30 ingredients by weight? A film made of a polymer mixture contained in each is adhered to one side of a base film mainly composed of a polypropylene polymer as a surface layer on both sides, and the thickness of the laminated film is 5 to 200μ,
It is an adhesive laminated packaging material in which the individual thickness of the surface layer is 0.2 to 10μ, the total thickness of the surface layer accounts for 0.5 to 50% of the thickness of the entire packaging material, and the shrinkability satisfies the following. .

Component A: A copolymer of butene and an α-olefin other than butene, the copolymerization ratio of butene being 70 to 99% by weight.

Component B: A copolymer of propylene and α-olefin having 4 to 10 carbon atoms, with a propylene copolymerization ratio of 70 to 95% by weight.

The polypropylene polymer forming the base film layer is a polymer mainly composed of propylene with a melting point of 140° C. or higher, preferably 150° C. or higher, such as isotactic polypropylene with an isotactic index of 85 (heavy O? , ethylene/propylene copolymer with an ethylene content of 7% (by weight) or less, propylene being 90% (by weight)
% or more of propylene and α-olefin having 4 to 6 carbon atoms, or a mixture of these polymers.

The polypropylene polymer preferably has an intrinsic viscosity (tetralin solution at 135° C.) of 1.6 to 3.0 d1/fl. In particular, it is preferably 1.6 to 2.5 d1/fl. If the intrinsic viscosity is less than 1.6 d1/9, it is difficult to obtain a transparent packaging material, and if it exceeds 3.0 d1/9, the extrudability decreases, making it particularly difficult to obtain a packaging material for the exterior of a package suitable for the present invention. This results in a packaging material that has a poor appearance, poor gloss, and reduces the internal product value. In the present invention, a low molecular weight thermoplastic resin may be blended into the base film, but the low molecular weight thermoplastic resin used here forms a mixture with good miscibility with the polypropylene polymer mixed together, and softens the base film. point (as measured by ASTM-D36-26) is in the range of 70 C to 150 C, and is thermally stable above 150 C, preferably about 20 C at 20 C.
Refers to a resin having a melt viscosity of 0,000 centipoise or less.

The term "miscible" herein means that no layer separation occurs when polypropylene and the above-mentioned low molecular weight thermoplastic resin are mixed. Also, “thermally stable” means that in the presence of air,
This means that no permanent change occurs in the properties of the resin even after heating for one hour at a given temperature. Additionally, the melt viscosity was measured using a Bruckfield viscometer heated to the indicated elevated temperature according to ASTM test method Dl 824-66. Examples of low molecular weight thermoplastic resins include natural and synthetic waxes, hydrocarbon resins, rosins, dammars, phenolic resins, chlorinated aliphatic hydrocarbon waxes, and chlorinated polyaromatic hydrocarbons. Natural waxes include wood wax, beeswax, spermaceti wax, etc., and synthetic waxes include those made by thermal cracking of high molecular weight polymers, or those made by known polymerization methods starting from monomers such as ethylene and propylene. means a synthetic wax etc. made of a low molecular weight polymer.

"Hydrocarbon resin" refers to hydrocarbon polymers derived from coke oven gas, coal tar fractions, cracked and deep-cracked petroleum feedstocks, essentially pure hydrocarbon feedstocks or turpentine, typically Examples of hydrocarbon resins include coumaron-indene resin, petroleum resin, styrene resin,
Examples include cyclopentadiene resin and terpene resin.

These resins are described in Kirk Osma's Encyclopedia of Chemical Technology, 2nd edition, Volume 11, 2.
42-255 (1966). "Coumaron-indene resin" refers to hydrocarbon resins recovered from coke oven gas or obtained by polymerization of resin formations present in coal tar distillates, phenol-modified coumaron-indene resins, or derivatives thereof. good,
These resins are described in the above literature, 2nd edition, Vol. 11, 243-247.
It is written on the page.

"Petroleum resin" refers to a hydrocarbon resin obtained by catalytic polymerization of deeply cracked petroleum raw materials, and these petroleum raw materials generally include styrene, methylstyrene, vinyltoluene, indene, methylindene, butadiene, isoprene, and piperylene. , containing a mixture of resin formers such as pentylene.

This resin is described in the above-mentioned document, 2nd edition, volume 11, pages 248-250. The term "1-styrene polymer" refers to a low molecular weight homopolymer of styrene, or a copolymer containing styrene and, for example, α-methylstyrene, vinyltoluene, butadiene, or the like.

6-cyclopentadiene resin refers to cyclopentadiene homopolymers and copolymers derived from coal tar fractions or separated petroleum gas.

These resins are produced by holding cyclopentadiene-containing raw materials at elevated temperatures for considerable periods of time. Depending on the temperature maintained, either dimers, trimers or high polymers are obtained. These resins are described in the above literature, 2nd edition, Volume 11, 25.
It is described on pages 0-251. The term "terpene resin" refers to polymers of terpenes, which are hydrocarbons with the general formula ClOHl6, present in most essential oils and plant oleoresins, and phenol-modified terpene resins.

Suitable terpenes include, for example, α-pinene, β-pinene, dipendene, limonene, myrcene, bornylene, gamphene and similar terpenes. This resin is described in the above-mentioned document, 2nd edition, volume 11, pages 252-254. "Rosin" refers to resinous substances naturally occurring in pine tree oleoresins and rosin esters, modified rosins such as fractional distillation, hydrogenation, dehydrogenation, or the like.

These substances are described in the above-mentioned literature, Vol. 17, pp. 475-505. "Danmaru" refers to a colorless to yellow substance or its analogues that naturally exist in plants such as Futabaceae and Orchidaceae. (published in 1962).

0 Phenol resin refers to a reaction product of phenols and aldehydes.

In addition to phenol itself, cresol, xylenol, p
-Tert-butylphenol, P-phenylphenol or analogs thereof are mentioned as the phenolic component,
Formaldehyde is the most common aldehyde, but aldehydes include acetaldehyde, furfuraldehyde, and the like. These resins are described in the above-mentioned Encyclopedia, Vol. 15, pp. 176-207.
``Chlorinated aliphatic hydrocarbon wax'' refers to something like chlorinated paraffin wax, which is usually called ``chlorinated wax,'' and a typical wax contains about 30 to 70% by weight of chlorine.

"Chlorinated polynuclear aromatic hydrocarbon" refers to a chlorinated hydrocarbon having two or more aromatic rings, such as two or more chlorinated biphenyl, terphenyl, etc., or a mixture thereof.

Typical ones contain about 30-70% chlorine by weight. The properties of the base film layer in the present invention are as follows. The packaging material may contain other polymers in amounts that do not reduce the packaging material, and by containing antistatic agents, lubricants, anti-locking agents, etc., it is possible to obtain packaging materials with improved automatic packaging properties.

In order to obtain a sealed package, the film is attracted by static electricity in the packaging material supply section of an automatic packaging machine, is wrapped around the blade of a cutter, or is pulled by electrostatic attraction to a guide plate, and the packaging material is It must be avoided that the supply does not reach the packaged item in a constant and direct manner.

Regarding this point, the present inventors discovered the following new fact. That is, the phenomenon of static electricity generated by automatic packaging machines can be significantly improved by incorporating an antistatic agent into the base film layer of the film. In particular, there is an acceleration phenomenon when a low molecular weight thermoplastic resin is mixed, and by acceleration, a more remarkable effect is exhibited and the film supplyability is improved. In the present invention, at least one side of the base film layer contains 5 to 70% by weight of the following component A and 95% by weight of component B.
~30 weight? A film consisting of a polymer mixture containing each is adhered.

Component A: A copolymer of butene and an α-olefin other than butene, the copolymerization ratio of butene being 70 to 99% by weight.

Component B: A copolymer of propylene and α-olefin having 4 to 10 carbon atoms, with a propylene copolymerization ratio of 70 to 95% by weight.

The component A polymer is a copolymer of butene and an α-olefin other than butene, with a butene copolymerization ratio of 70 to 99% by weight.

α-olefins other than butene include ethylene, propylene, benzene, hexene, 4-methyl, benzene-1
Examples include, but are not limited to, 1 octene, decene, etc. This copolymer has a melting index of 0.
．． Preferably it is 5 to 159/10 minutes. The B component polymer is propylene and α-olefin having 4 to 10 carbon atoms, with a copolymerization ratio of 70 to 95% by weight. Examples of the α-olefin having 4 to 10 carbon atoms include, but are not limited to, benzene, hexane, 4-methylbenzene-1, octene, decene, etc. In such a copolymer, the propylene content is 70% by weight. If it is less than that, transparency and gloss will deteriorate, and the coefficient of friction at high temperatures will be high, resulting in poor slippage during heat sealing, which will cause stutters and wrinkles on the film or sheet, making it difficult to obtain a sealed package using an automatic packaging machine. In addition, when the sequential biaxial stretching is carried out, it is easy to adhere or fuse to the heated stretching rolls, and it is difficult to obtain a packaging material made of a film or sheet that is commercially smooth and has an excellent appearance without scratches. In addition, if the propylene content is 95% (by weight) or more, the heat sealing properties will deteriorate and it will be difficult to heat seal at low temperatures and at high speeds, and the heat seal temperature will have to be high, making the heat sealing part The film is damaged by heat and a beautiful package cannot be obtained.The mixing ratio of the A-component polymer and B-component polymer is 5 to 70% by weight for the former and 95 to 30% by weight for the latter.
It is.

In the present invention, it is preferable to mix 0.1 to 0.15 parts by weight of silicone oil with respect to 100 parts by weight of the above polymer mixture.

Silicone oils that can be used in the present invention include polydimethylsiloxane, polymethylphenylsiloxane, olefin-modified silicone, polyether-modified silicone modified with polyethylene glycol or polypropylene glycol, olefin/polyether-modified silicone, epoxy-modified silicone, and amino-modified silicone. , is a silicone oil containing modified siloxaquine bonds such as alcohol-modified silicone. Among these silicone oils, olefin-modified silicone, polyether-modified silicone, olefin/polyether-modified silicone, etc. are particularly excellent. The silicone oil improves the coefficient of friction of the film when heated, reduces the sliding resistance that occurs during hot plate sealing in automatic packaging machines, and prevents wrinkles, resulting in a beautiful appearance and high sealing performance. The basis for obtaining a film that maintains the performance of adhesion to the packaged object without sagging can be created. A beautiful seal can be obtained by preventing the gloss from decreasing due to sliding. In the present invention when silicone oil is used in combination, the high temperature friction coefficient is reduced to 1 when performing sliding heat sealing.
．． It can be reduced to 4 or less. The silicon oil, which is an important requirement to achieve the above object, preferably has a viscosity in the range of 50 to 10,000 centistokes at room temperature, and more preferably a low viscosity of 50 to 300 centistokes. Things are good. In addition to the silicone oil, ethylene oxide adducts of star oil with a softening point of 70°C to 140°C, oxidized synthetic waxes, higher fatty acid alkyl esters, polyhydric alcohol alkylate ethylene oxide adducts, fatty acid amide, etc. are used in combination. By doing so, the effect can be further enhanced. The mixture of these is 1 to 300 parts, especially 5 parts to 100 parts of silicone oil.
It is desirable to use it in a range of 0 to 300 parts. By using this additive in combination with silicone oil, it prevents the state slip that tends to occur when using only silicone oil at room temperature to 100℃ or less, and smoothes the sliding on various metal guide plates of automatic packaging machines. This can prevent packaging defects. Furthermore, it improves slippage under high temperature and pressure, which is extremely important for obtaining the sealed package of the present invention. This specific value is a high temperature friction coefficient of 1.4 or less, preferably 1.0 or less. The silicone oil and the above-mentioned additives are not only good, but the film tends to reduce the heat sealability of the sheet and also tends to reduce the transparency.
Therefore, simply adding it tends to reduce the low-temperature heat-sealability, so heat-sealing must be performed at a slightly higher temperature. The mixing range of the present invention indicates a preferable mixing amount that satisfies this point. Generally, when heat sealing is performed at high speed and high temperature using an automatic packaging system, the film forms gaps on the surface of the sheet and heat shrinks, making it impossible to obtain a smooth sealing surface.

That is, biaxially stretched films such as polypropylene have high crystallinity and melting point, and cannot achieve uniform shrinkage like polyvinyl chloride and the like. In the case of biaxially stretched polypropylene film, the portion that comes into contact with the hot plate contracts, and depending on the contact conditions, a sealing surface that is extremely uneven can be obtained. This phenomenon causes a partial seal failure due to the occurrence of unevenness in the tightly sealed package which is the object of the present invention, and a highly airtight package cannot be expected. In order to obtain these close-fitting and sealed packages, it is of course possible to perform low-temperature heat sealing as described above.
It is necessary that the sealing strength of the heat-sealed part is strong even in the heated state, and that the coefficient of friction in the heated state is low. Specifically, it is desirable that the heat seal strength at 120°C is 409/CTIl or more. The heat-sealed package is then heat-shrinked using a heat-shrinker such as a heat-shrink tunnel. However, if the heat-sealing strength decreases after heat-shrinking, the seal part may come off or shift due to shrinkage stress, resulting in loss of adhesion. It will get wet, and of course the sealing performance will deteriorate. The heat-sealing strength retention rate of the heat-shrinkable packaging material of the present invention is 60% or more, preferably 80% or more. Further, it is desirable that the friction coefficient at high temperature is, for example, 1.4 or less at 120°C. Furthermore, in order to heat-shrink the article after packaging to obtain a completely adhesive package, the present invention requires not only the above-mentioned properties but also the following shrinkage properties. SFm≧3.5% By having SF (SFm and SFt) of 3.5% or more, when automatically packaged, there is no gap between the packaged object and the packaging material over a wide heat shrinkage temperature range. It is possible.

Further, by satisfying ISl-Sml≧1.5%, it is possible to avoid wrinkles remaining at the corners of the package when the article is packaged and then heat-treated to form a shrink-tight package.

The state of occurrence of wrinkles is shown in FIG. Also, 1St-Sml
Figure 2 shows the value of and the state of wrinkles. If each is not 1.15% or more, relatively large wrinkles will remain in the form of folds when the article is packaged and then heat-shrinked.

If wrinkles or folds remain, it will not only give a poor appearance but also cause damage due to snagging during transportation or handling. The heating method of the heat shrinker (heat shrink oven) includes infrared heating, electric heating, flame heating, hot air heating, and hot water heating.

As for the method of manufacturing the packaging material of the present invention, layers A and B can be bonded together using an adhesive, but layers A and B are extruded from separate extruders, and the composite flow is carried out in a melt-down state. The co-extrusion method involves making and extruding the film, or the laminating method, which involves melt-extruding it separately and then cooling and solidifying it before laminating it into a ml film. A composite film sheet can be obtained by bonding the film or by continuously stretching the film.

These force methods may be applied to either a flat film or an annular film, and although the present invention can be used with an unstretched film, it is preferable to use a film that has been at least uniaxially stretched. Particularly preferably, biaxial stretching provides a more effective sealing material. A feature of the packaging material of the present invention is that it can be manufactured by a sequential biaxial stretching method in which heated rolls are used during longitudinal stretching, and of course simultaneous stretching is even easier.

The laminated film of the present invention is advantageous because sequential biaxial stretching can obtain a packaging material with good heat-sealing strength by obtaining a strong composite layer bonding force between layers, and can economically produce a laminate. The significance is extremely high. Suitable conditions for stretching will be described below.

In case of uniaxial stretching, 3.5~
Stretch 10 times.

The stretching temperature is usually 100 to 160°C in the case of roll stretching, and 140 to 165°C in the case of tenter stretching. In the present invention, when the film is sequentially stretched biaxially, the longitudinal force is 3.5 to 10 times, preferably 3.8 to 7 times
．． Stretched 5 times, 4 to 12 times in the transverse direction, preferably 6 to 9 times. When simultaneous biaxial stretching is carried out, it is carried out at 140 to 165 C. In the case of sequential biaxial stretching, the first stage is 1000C~
160°C, preferably Step 10 is C to 130°C, second stage is 1400C to 165°C, preferably 145°C to 160°C
It is. It is not necessary to carry out heat treatment after stretching, but it may be carried out within a range that does not cause loss of the heat shrinkage properties due to changes in the film over time, reduction in winding tightness of the product roll, etc. Generally, it is 3 to 60 seconds at 500C to 135C. In order to obtain a close-fitting, sealed package, when the object to be packaged is immediately tightly and hermetically packaged with the packaging material of the present invention, or the object to be packaged is first shrunk into a box by a certain number and then the box is wrapped in one or more boxes. A large number of products may be hermetically packaged using the laminated packaging material of the present invention. In either case, it is sufficient that the adhesive is thermally melted and bonded in close contact with the packaged item. The thickness range of the laminated packaging material used in the present invention is determined depending on its use as a close-contact packaging body, and is in the range of 5 to 200 μm.

A commonly used range is 15-60μ. The thickness of the inner surface layer of the packaging material of the present invention is 0.2 of the total thickness of the packaging material.
~50% range. The packaging material of the present invention may have a metal vapor deposited layer formed on a portion of the surface layer. Furthermore, the surface layer can be printed, and a metal vapor deposited layer can also be formed after printing. It is also possible to perform an anchor coating using a conventional anchor coating agent before metal vapor deposition. Examples of anchor coating agents include thermosetting types such as polyisocyanate, urethane, and melamine, polyethyleneimine, titanium, acrylic ester, ethylene vinyl acetate, vinylidene chloride, chlorinated polyolefin, and linear. Various types such as copolyester types can be used alone or in combination. When the packaging material of the present invention is used to tightly package an article using an automatic packaging machine and then pass it through a heat shrinker to form a tightly packaged product, the thickness of each surface layer is 0 within the above thickness ratio range. .2 to 10μ, particularly preferably about 0.2 to 3μ.

Before describing the embodiments of the present invention, the sinusho force method will be described.

1) Base: In accordance with JIS-K-6714, the base was selected using a "Base Tester" manufactured by Toyo Seiki Co., Ltd.

2) Automatic feeding ability: The packaging material was automatically fed and evaluated using a W-37 model packaging machine manufactured by Tokyo Automatic Machinery Co., Ltd.

O No problem △ Supply was sometimes unavailable

O No problem △ Noticeable wrinkles The peel strength was measured at a speed of 1/min.

5) Adhesive packaging properties: Appearance of the packaged product after being packaged with the automatic packaging machine used in 2) above and passed through a heating oven to cause heat shrinkage.

◎ It was completely adhered, there were no wrinkles, and it was possible to wrap it under tension.

○ Although it is in close contact, there are some wrinkles.

I was able to wrap it under tension. △ There are parts that are in close contact with each other and parts that are not in close contact with each other, and wrinkles are present.

X There are many wrinkles.

6) Free heat shrinkage factor SF: Cut the film into pieces of 15m1L width and 300mm length, mark the length between gauges of 2007nm, leave the sample in a free state and heat shrink at 12"C to shrink. It was calculated using the following formula from the front and rear lengths L and L'.

7) Heat shrinkage rate under restraint s: 110m1L x 70m7! Fix the film to a pair of parallel sides of the long length frame L, leave the other pair of parallel sides unfixed, heat shrink it at 12'C, and use the following formula from the lengths L and L'' before and after shrinkage. I asked for it.

Example 1 Isotactic polypropylene 1 with an intrinsic viscosity of 2.0 d1/9 (using a tetralin solution at 135°C) as the base layer 1
The composition was prepared by mixing 1.0 part (by weight) of an alkylamine ethylene oxide adduct and 0.50 part by weight of glycerin stearate with respect to 00 parts by weight.

On the other hand, the surface layer 2 was made of butene-1/ethylene copolymer containing 4.5% (by weight) of ethylene (melt index: 2.5%).
9/10 minutes) 50 (weight)% and propylene content 80 (
(wt)% propylene/butene-1 copolymer 100 (wt.) parts of a 50 (wt.)% polymer mixture, 0.4 (wt.) parts of glycerin fatty acid ester, and hydroxystearamide (manufactured by Nippon Kasei Co., Ltd., Diamid KH). 0.5 (weight) part,
A composition in which 0.1 part (by weight) of polyethylene wax (molecular weight 2000) was mixed was used.These compositions were melt-extruded from two extruders to obtain a three-layer unstretched film of 2/1/2. The unstretched film has a thickness of 1000μ and is stretched 5 times in the machine direction at 130°C, then 8.0 times in the transverse direction at 160°C, and then 4 times at 100°C.
After passing through a temperature-controlled oven for 8 seconds while giving a relaxation rate of
A biaxially stretched film was obtained. This film has a surface tension of 4
0 dyne/CI! corona discharge treatment on the surface and printing (
Printing ink: NPA manufactured by Toyo Ink Co., Ltd.) (1
), and those with metal vapor deposition after printing (printing ink is the same as above) (
) were prepared and packaged into drug cases using an overlap machine. After packaging, the heated air shown in Table 1 was blown from above and below, and the product was passed through an oven for the time shown in Table 1 to shrink the outer film to obtain a tight package. Comparative Example 1 Biaxial stretching was carried out in the same manner as in Example 1, and then 15
The product was subjected to 5% relaxing heat fixation at 5° C., treated in the same manner as in Example 1, and packaged in the same manner.

Comparative Example 2 Composite biaxial stretching was carried out in the same manner as in Comparative Example 1, except that a propylene/ethylene copolymer (ML 2.59/10 min) with an ethylene content of 3.4% (by weight) was used as the constituent polymer of the surface layer 2. It was made into a film.

The obtained film was packaged using an automatic packaging machine in the same manner as in Example 1, and passed through a shrink oven under the same conditions. Comparative example 3 Isotactic polypropylene (intrinsic viscosity 12.0
d1/9) 60% (by weight) and polybutene-140% (by weight) was mixed with the same additive content as in the base layer of Example 1, and the mixture was melt-extruded to obtain a thickness, 1
An unstretched film of 000μ was obtained and stretched at 110°C for 5
．． The film was stretched 0 times, then stretched 8.0 times in the transverse direction at 145° C., and heat-set under the same conditions as in Comparative Example 1 to obtain a biaxially stretched film with a thickness of 25 μm.

The biaxially stretched film was automatically packaged in the same manner as in Example 1 and passed through a heat shrink oven. In the packaging material of the present invention, the base value was low, the packaged items looked beautiful, there were few wrinkles in the heat-sealed portion of the package, and the package was packaged extremely tightly after passing through the shrink oven. The extent of this can be judged from the length of the residual slack. In Comparative Example 2, since automatic feeding was not possible, packaging was performed intermittently and then shrink-wrapped. However, tight packaging was difficult. Next, Table 2 shows the changes in the packaging material after close-contact packaging. In addition, in Comparative Examples 1 to 3, the shrinkage conditions were set to 150° C. for 0.5 minutes since tight packaging did not occur even at 130° C. for 0.5 minutes. Example
2 90% polypropylene forming the base layer of Example 1 and 10% petroleum resin (argon Pll5 manufactured by Arakawa Forestry Chemical Co., Ltd.)
% (by weight) of an alkylamine ethylene oxide adduct, 0.2% (by weight) of a fatty acid monoglyceride, and 0.6% (by weight) of an erucic acid amide.
1% (by weight) was used.

The mixed composition was previously made into a master patch and diluted to give the final strength as described above. The mixed composition was melt-extruded at 27'C, cooled on one side with a cooling roll at 250°C while water-cooled at 25'C, and then stretched 5.0 times in the machine direction at 13'C. On both surfaces of the uniaxially stretched film, a butene-1/hexene copolymer (butene content of 97 (weight) %) and 20 (weight) % of propylene and a propylene-1/hexene copolymer (butene content of 97 (weight) %) and propylene-propylene content of 75 (weight) % are formed on both surfaces of the uniaxially stretched film. A mixture of 80% (by weight) of butene-1 copolymer, 0.3% (by weight) of hydroxystearamide, 0.6% (by weight) of calcium carbonate, and 2 (by weight) of polyethylene wax based on 100 parts by weight of the mixture. % was mixed. This mixture was melted at 265°C, extrusion laminated on both sides of the axially stretched film of the base layer, and then stretched 8.5 times in the transverse force direction at 155°C to obtain a composite stretched film. After stretching, heat setting was performed at 105° C. for 5 seconds. Both sides of the film are subjected to corona discharge treatment, and one side has a wet tension of 34 dynes/CT! L, one side obtained 42 dynes/CTn. After printing and drying the surface of this 42 dynes/Cln, anchor coating was applied with an isocyanate adhesive, and then aluminum was metal-evaporated to a thickness of 400 mμ. However, metal vapor deposition on the heat-sealed part was avoided.

The film was used to package cases of thiokolate. After packaging the Chiyokolate, heat the air at 185°C for 2.
The package was heat-shrinked for 5 seconds to obtain a tightly sealed package, which was immediately cooled in a cooling chamber to obtain an externally and tightly sealed package. Both the ink layer and the metal vapor deposited layer had good gloss and no discoloration.

An unstretched film with a thickness of 1000μ was obtained using the same composition and force method as in Example 3, Comparative Example 4, and Example 1, and the unstretched film was subjected to longitudinal force direction and transverse force direction at the temperature and magnification shown in the table below. A film was obtained by sequentially stretching and heat treatment, followed by relaxation and cooling in the same manner, and was packaged into a drug case using the same overlap machine.

The results are shown below. Adhesive packaging property is 12'C×
This is the data after passing through the oven for 1 minute. A, B,
F, G, K, L, and M are comparative examples.

Example 4, Comparative Example 5 Films were formed and stretched using the same composition and force method as in Example 1, varying the thickness of the surface layer (the overall thickness was the same), and a packaging test was conducted in the same manner.

The results are shown below. The thickness of the surface layer is O. If it is less than 2μ, not only will the sealing strength be insufficient, but the automatic feeding performance will also deteriorate.
Static electricity is also likely to occur. Heat-sealability deteriorates, so the sealing temperature also needs to be high, and wrinkles are more likely to occur.
When the force exceeds 10μ, the heat sealability improves, but the frictional resistance of the sealing portion becomes high and wrinkles are likely to occur. Example 5 In Example 1, the polymers constituting the surface layer were a butene-ethylene-propylene copolymer (copolymerization ratio 90:5:5 weight ratio) and a propylene-butene-hexene copolymer (copolymerization ratio 78: 17:5 weight ratio) and 50:50 (weight ratio)
Packaging materials were obtained under the same conditions except that the film tension heat treatment temperature and time were as follows.

E and F are comparative examples.

[Brief explanation of the drawing]

Figure 1 shows the shape of the package when wrinkles occur at the corners.

Claims (1)

[Scope of Claims] 1 5 to 70% by weight of the following component A, and 95 to 95% of the following component B
A film made of a polymer mixture containing 30% by weight each is adhered as a surface layer to one or both sides of a base film mainly composed of a polypropylene polymer, and the thickness of the laminated film is 5 to 200μ, and the surface layer The individual thickness of the surface layer is 0.2 to 10 μ, the total thickness of the surface layer accounts for 0.5 to 50% of the total thickness of the packaging material, and the shrinkage property is SFm≧3.5% SFt≧3.5% |St-Sm|≧1.5% Formula 1 SFt-St≧1.15% Formula 2 SFm-Sm≧1.15% Formula 3 SF: Free heat shrinkage rate at 120°C S: Restrained heat shrinkage at 120°C Ratio m: An auxiliary symbol indicating the longitudinal direction t: An adhesive laminated packaging material that satisfies the horizontal direction Polymer. Component B: A copolymer of propylene and an α-olefin having 4 to 10 carbon atoms, with a propylene copolymerization ratio of 70 to 95% by weight. 2. An adhesive metal vapor-deposited laminated packaging material, wherein a metal vapor-deposited layer is formed on a portion of the surface layer of the adhesive laminated packaging material according to claim 1. 3. The surface layer of the adhesive laminated packaging material according to claim 1 or 2 contains 0.01 parts by weight of silicone oil per 100 parts by weight of a polymer mixture containing a component A polymer and a component B polymer, respectively. An adhesive laminated packaging material formed from a composition containing ~0.15 parts by weight. 4. The base film of the adhesive laminated packaging material according to claim 1, 2, or 3 comprises 80 to 98% by weight of a polypropylene polymer and 20 to 98% by weight of a low molecular weight thermoplastic resin.
An adhesive laminated packaging material which is a film containing 2% by weight. 5 Claims 1, 2, 3, or 4
The adhesive laminated packaging material according to item 1, wherein the base film of the adhesive laminated packaging material is a film containing an antistatic agent in its constituent polymer.