JPH0834862A - Thermally shrinkable film - Google Patents

Abstract

PURPOSE:To provide a thermally shrinkable film which is free from plasticizer blooming on the surface, a sweat-out phenomenone, loss of clarity, clouding, etc. CONSTITUTION:A thermally shrinkable film is formed from a resin compsn. obtd. by compounding 100 pts.wt. polypropylene resin with 5-60 pts.wt. plasticizer. The resin used has a wt. average mol.wt. of 80,000-500,000 and amts. of resin dissolution by the cross-fractionation method at 0-20 deg.C. at 20-70 deg.C, and at 70-110 deg.C of lower than 5 wt.%. 8-30 wt.%. and 70-95wt.%, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-shrinkable film containing a plasticizer, and more specifically, bleeding (leaching) of the plasticizer on the film surface, a sweaty phenomenon (sweat), and loss of transparency. The present invention relates to a heat-shrinkable film that does not cause a phenomenon (devitrification) or cloudiness. More specifically, the present invention provides 80
The present invention relates to a heat-shrinkable film which can be heat-shrinked by 20% or more at around 0 ° C and can be sterilized at 85 ° C or more. The present invention also relates to a heat-shrinkable film which has a small specific gravity and is easy to separate and collect from a container when used as a shrink-wrapping material for a container and has no environmental problem and is safe.

[0002]

2. Description of the Related Art In recent years, polyvinyl chloride film, polystyrene film, polyester film and the like have been used as shrink labels for shrink-wrapping beverage containers.

Polyvinyl chloride resin has good compatibility with a plasticizer and therefore has good thermoformability, and a film obtained from polyvinyl chloride has excellent transparency and gloss. Polyvinyl chloride film is suitable for shrink wrapping of containers, but has environmental problems such as generation of toxic gas when incinerated. Further, since the polyvinyl chloride film has a large specific gravity, it has a drawback that it is difficult to separate and collect it from the container.

Polystyrene film is suitable for shrink wrapping of containers, but its heat resistance is 80 ° C. or lower, so
It is not suitable for sterilization with hot water above ℃ or sterilization during the production of retort pouch foods.

Polyester films can be used for shrink wrapping of containers, but have a disadvantage that they are difficult to separate and collect from containers like polyvinyl chloride because of their large specific gravity.

Polyolefins such as polyethylene and polypropylene generally have poor compatibility with plasticizers, and for example, 5 to 10 parts by weight of a plasticizer (for example, tri-n-butyl citrate) is added to 100 parts by weight of a polyethylene resin. When added in a small amount, the two are not compatible, so in the film formed using this, all the plasticizer migrates to the film surface, and the film surface is covered with the plasticizer and sticky. Becomes

Actually, 100 parts by weight of low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene block copolymer, ethylene-propylene random copolymer alone or a blend of these resins are mixed with various plastics. 5 to 5
A film was molded with 60 parts by weight added, but the film could not be molded due to fluctuations during extrusion, and leaching of the plasticizer on the film surface, cloudiness, etc. occurred, and a satisfactory film could not be obtained. It was

The polypropylene resin film is excellent in transparency, gloss, heat resistance, rigidity, low specific gravity and the like, and is suitable for use as a packaging material. However, the polypropylene-based resin film is heat-shrinkable at a temperature of 100 ° C. or higher, but hardly shrinks in a low temperature range of 70 to 80 ° C., and thus is not suitable as a shrink-wrapping material. Therefore, various studies have been conducted in order to use a polypropylene resin film as a shrink wrapping material having low temperature heat shrinkability (heat shrinkage at 80 ° C. is 20% or more in the stretching direction). To achieve low temperature heat shrinkability, 60
It is necessary that the film can be stably stretched about 3 to 4 times without being whitened in a stretching region of 70 ° C. Therefore, attempts have been made to use a propylene-ethylene random copolymer in a proportion of 2 to 10% by weight or to add an ethylene-α-olefin copolymer or a petroleum resin to the propylene-ethylene random copolymer. There is.
By these means, the stretching temperature of the polypropylene resin film of 110 to 120 ° C. is usually lowered to about 80 to 90 ° C., but it is still insufficient.

By the way, the conventional polypropylene resin 1
By adding 10 to 60 parts by weight, preferably 20 to 30 parts by weight, to 00 parts by weight, the obtained film can be satisfactorily stretched without whitening even in the stretching region of 60 to 70 ° C. However, bleeding out of the plasticizer, plasticization, and loss of gloss occurred, which was not practical.

[0010]

SUMMARY OF THE INVENTION The present invention overcomes the above-mentioned drawbacks of the prior art. By using a specific polypropylene resin, plastic film bleeding (leaching) or sweating on the film surface may occur. An object of the present invention is to provide a heat-shrinkable film that does not cause a phenomenon (perspiration), a phenomenon that transparency is lost (devitrification), or cloudiness. The present invention also provides
It is an object of the present invention to provide a heat-shrinkable film capable of 20% or more heat shrinkage at around 0 ° C and sterilizable at 85 ° C or more. A further object of the present invention is to provide a heat-shrinkable film which has a low specific gravity and is easy to separate and collect from a container when used as a shrink-wrapping material for a container and has no environmental problems and is safe.

[0011]

Means for Solving the Problems As a result of intensive studies, the inventors of the present invention have selected, as a resin component, a polypropylene resin having a specific weight average molecular weight and having a resin elution amount in a certain range at a specific temperature. It was found that the above object can be achieved by forming a film and using it in the heat-shrinkable film, and the present invention has been completed based on the finding.

The heat-shrinkable film of the present invention is a polypropylene resin having a weight average molecular weight in the range of 80,000 to 500,000, and has a resin elution amount at 0 ° C. or higher and 20 ° C. or lower by the cross fractionation method. It is less than 5% by weight of the total polypropylene-based resin amount, the resin elution amount at a temperature of more than 20 and 70 ° C. is 8 to 30% by weight of the total polypropylene-based resin amount, and the resin elution amount at a temperature of more than 70 and 110 ° C. is less than The resin composition is formed by adding 5 to 60 parts by weight of a plasticizer to 100 parts by weight of a polypropylene resin having a composition in the range of 70 to 95% by weight based on the total amount of the polypropylene resin.

In a preferred embodiment, the plasticizer is tri-n-butyl citrate, diisodecyl phthalate, diisodecyl adipate, dioctyl sebacate,
It is selected from the group consisting of trioctyl phosphate, -n-butyl oleate and diisobutyl adipate.

In a preferred embodiment, the heat-shrinkable film is stretched at least twice in at least one direction at a temperature of 80 ° C. or lower.

In a preferred embodiment, the polypropylene resin is a propylene-ethylene copolymer or a propylene-α-olefin copolymer. In the presence of a titanium compound catalyst and an aluminum compound catalyst, these resins are prepared by first polymerizing the first propylene-based resin in the first step, and then in the second and subsequent steps, the produced titanium-containing propylene-based resin and the above It can be obtained by copolymerizing propylene and ethylene, or propylene and α-olefin in the presence of a compound catalyst, and then crosslinking these copolymers.

In a further preferred embodiment, the titanium-containing propylene resin produced in the first step is a propylene homopolymer, a propylene-ethylene copolymer, or a propylene-α-olefin copolymer.

The present invention will be described in detail below.

The weight average molecular weight of the polypropylene resin used in the present invention is, for example, High Temperature G manufactured by WATERS.
It can be measured on a PC (150 CV). The weight average molecular weight of the polypropylene resin used in the present invention is 80,000.
0 to 500,000, preferably 80,000 to
450,000, and more preferably 100,0
It is 00 to 400,000. Weight average molecular weight of 80,
If it is less than 000, stretching of the film becomes difficult, and 500,
If it exceeds 000, sufficient flexibility cannot be obtained. The amount of resin eluted by the cross fractionation method used in the present invention is measured as follows. Polypropylene resin is 140 ℃ first
Alternatively, the polypropylene resin is dissolved in o-dichlorobenzene at a temperature at which the polypropylene resin is completely dissolved and cooled at a constant rate to form a thin polymer layer on the surface of an inert carrier prepared in advance in the order of increasing crystallinity and increasing molecular weight. Next, the temperature of the generated polymer layer is continuously or stepwise increased, the concentrations of the components eluted in sequence are detected, and the composition distribution (crystallinity distribution) is measured <temperature rising elution fractionation>. At the same time, the molecular weight and molecular weight distribution of the component are measured by high temperature GPC. For example, the temperature rising elution fractionation (TR
EF = Temperature Rising Elution Fractionation part and high temperature GPC (SEC = Size Exclution Chromatogra)
A cross fractionation chromatograph <CFC-T150A type: manufactured by Mitsubishi Petrochemical Co., Ltd.> that includes a ph) part as a system can be used.

The polypropylene resin used in the present invention is
The resin elution amount at 0 ° C. or higher and 20 ° C. or lower by the cross fractionation method is less than 5% by weight, preferably 2 to 3% by weight, based on the total amount of polypropylene resin. This elution amount is 5
When the content is more than 5% by weight, the transparency and gloss of the film deteriorate.

This resin is 20% by the above-mentioned cross fractionation method.
The resin elution amount at a temperature higher than 70 ° C and lower than 70 ° C is 8 to 30% by weight, preferably 10 to 20% by weight, based on the total amount of polypropylene resin. If it is less than 8% by weight, the film lacks flexibility, and if it exceeds 30% by weight, the transparency and gloss of the film are deteriorated and the stretchability is deteriorated.

Finally, the resin elution amount by the above cross fractionation method at a temperature higher than 70 ° C. and lower than 110 ° C. is 70 to 95% by weight, preferably 80 to 90% by weight of the total amount of polypropylene resin. If it is less than 70% by weight, the rigidity of the film is lost, and if it exceeds 95% by weight, the compatibility with the plasticizer is lowered and the film is easily torn.

The polypropylene resin used in the present invention is 20 ° C. or more and 20 ° C. or less by the above cross fractionation method.
The weight average molecular weight of each elution resin at temperatures above 70 ° C and below 70 ° C and above 110 ° C and below 25,000 to 30,000.
0, 30,000 to 90,000, 100,000 to 4
It is preferably in the range of 0,000.

In the polypropylene resin used in the present invention, the elution amount and the weight average molecular weight in each temperature range being within the above ranges indicate that the elastic modulus, strength, ductility, heat shrinkability and heat resistance of the film are high. It is very important for controlling physical properties.

The polypropylene resin used in the present invention is produced, for example, by the following multistage polymerization method.
First, as a first step, polymerization is carried out in the presence of a titanium compound catalyst and an aluminum compound catalyst using a propylene monomer and optionally an α-olefin monomer other than propylene to obtain a first polypropylene resin. This polypropylene resin is a propylene homopolymer, a propylene-ethylene copolymer, a propylene-
It may be an α-olefin copolymer or the like. In the second step, the first polypropylene-based resin containing the titanium compound catalyst and the aluminum compound catalyst is copolymerized with an olefin monomer (for example, ethylene, propylene, or α-olefin), A polypropylene resin of 2 is obtained. The second polypropylene resin obtained by this two-step reaction may be a propylene-ethylene copolymer or a propylene-α-olefin copolymer. Similarly, a multi-step copolymerization reaction can be performed depending on the purpose. The feature of this production method is that the polymerization is not completed in one step, but multi-step polymerization of two or more steps is performed. This allows multiple types of polymers to be built up in succession, producing blend-type copolymers at the molecular level, which is quite different from conventional polymer blends.

Generally, in the case of polymer blending, one method is to increase the molecular weight of the rubber component to be blended in order to improve appropriate flexibility and elasticity. In the case of the polypropylene resin used in the present invention, the rubber component corresponds to the component (α-
(Olefin-propylene, ethylene-propylene), and this component has a high molecular weight, and therefore has a high melt viscosity. This rubber component can be finely dispersed in the polypropylene resin by using the above-mentioned multistage polymerization method. However, in a blending method using an ordinary extruder or the like, when a rubber component having such a high molecular weight is used, the melt viscosity is high. Therefore, a resin having a finely dispersed morphology like the polypropylene resin used in the present invention is It cannot be made. Therefore, even if the above-mentioned plasticizer is mixed, it is incompatible and cannot be applied. A polypropylene resin having a finely dispersed morphology of the polypropylene resin used in the present invention can obtain a polypropylene resin capable of containing a plasticizer, similar to PVC.

As such a manufacturing method, for example, there is a method described in JP-A-4-224809. In this method, as a titanium compound, for example, titanium trichloride and magnesium chloride are co-ground, and this is orthotitanic acid n
A spherical solid titanium catalyst having an average particle diameter of 15 μm, which is obtained by treating with —butyl, 2-ethyl-1-hexanol, ethyl p-toluate, silicon tetrachloride, diisobutyl phthalate, or the like, is used. In this method, a silicon compound, especially diphenyldimethoxysilane, is added as an electron donor to the polymerization tank, and ethyl iodide is further added. Further, JP-A-3-97747 discloses that a titanium compound obtained by treating an adduct of magnesium chloride and alcohol with titanium tetrachloride and an electron donor is used. In addition to these methods, for example, JP-A-4-96912, JP-A-4-96907, JP-A-3-174410, and JP-A-2-170803.
No. 2, 170, 802 and No. 3, 20543.
No. 9, JP-A No. 4-153203, and JP-A-6-63
Such a manufacturing method is described in, for example, Japanese Patent Publication No. 1-42553. In producing the polypropylene resin forming the heat-shrinkable film of the present invention, any known method as described above can be used. Examples of actual resins obtained by such a production method include "PER" manufactured by Tokuyama Soda Co., Ltd. and "Cataloy" manufactured by Highmont Co., Ltd.
Any of these can be used in the present invention.

The resin composition used for molding the heat-shrinkable film of the present invention contains 5 to 60 parts by weight of a plasticizer, preferably 2 to 100 parts by weight of the polypropylene resin.
It is obtained by containing 0 to 30 parts by weight.

As the plasticizer, tri-n-citrate is used.
Butyl (ATBC), Diisodecyl phthalate (DID
P), diisodecyl adipate (DIDA), dioctyl sebacate (DOS), trioctyl phosphate (TO)
P), -n-butyl oleate (Bu-OL), diisobutyl adipate (DIBA) and the like.

When the content of the plasticizer is less than 5 parts by weight based on 100 parts by weight of the polypropylene resin,
Stable stretching cannot be obtained in the stretching region of 60 to 70 ° C. On the contrary, when it exceeds 60 parts by weight, the gloss of the obtained film is lowered and the commercial value is impaired.

In the present invention, the resin composition may further include a stabilizer such as an antioxidant and an ultraviolet absorber, a filler such as precipitated barium sulfate, talc, calcium carbonate, mica and titanium oxide, a colorant and the like. Can be added.

The heat-shrinkable film of the present invention can be obtained, for example, by a method of molding the above resin composition to a predetermined thickness by a usual T-die method, inflation method, calender method or the like.

The heat-shrinkable film of the present invention has a thickness of 30.
˜70 μm can be applied.

The heat-shrinkable film of the present invention can be used by stretching it at least 80 ° C. or less and at least 2 times or more in one direction. It is considered that the low temperature shrinkage of the obtained heat shrinkable film is further improved by the low temperature stretching.

The film may be a colorless and transparent film, a colored and transparent film, or a colored and nontransparent film.

[0035]

In the heat-shrinkable film of the present invention, due to the use of a specific polypropylene resin, plasticizer bleeding (leaching) on the film surface, a sweaty phenomenon (sweating), transparency It is possible to provide a heat-shrinkable film that does not cause the phenomenon (devitrification) or white turbidity. The heat-shrinkable film of the present invention can also have a heat shrinkage of 20% or more near 80 ° C and can be sterilized at 85 ° C or more. Further, since the heat-shrinkable film of the present invention has a relatively small specific gravity, when it is used as a shrink-wrapping material for a container, it can be easily separated and collected from the container and there is no environmental problem.

The reason why the heat-shrinkable film of the present invention has an excellent feature that leaching, perspiration, devitrification, cloudiness and the like do not occur is presumed as follows. It is considered that the polypropylene resin used in the present invention is alloyed by introducing a large amount of an amorphous polymer represented by ethylene-propylene copolymer into the polypropylene resin during the polymerization. The use of titanium-based catalysts, which are very active and have a long life, appears to have enabled some manufacturers to make resins of this type. There are several kinds of copolymers having different molecular structures in the polymer obtained by such polymerization, and therefore it is considered that a characteristic morphology is expressed in the alloy of the ordinary resin part such as polypropylene and these copolymer parts. . As a result, it is considered that the heat-shrinkable film of the present invention can contain a plasticizer.

[0037]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples.

<Example 1> Weight average molecular weight 260,00
0, the elution amount at each temperature by the cross fractionation method is 0 ° C or more 2
2.5% by weight below 0 ° C., 11% by weight above 20 ° C. and below 70 ° C., 86.5% by weight above 70 ° C. and below 110 ° C.,
Polypropylene resin (manufactured by Highmont, Catalloy K
T-011P, MFR5.0, density 0.900g / cm
³ ) To 100 parts by weight, 20 parts by weight of diisobutyl adipate (D14A manufactured by Sanken Kako Co., Ltd.) as a plasticizer was added to obtain a resin composition, and then 50 mm was prepared using this resin composition.
A film having a thickness of 50 μm was prepared using an inflation extrusion facility.

With respect to the obtained resin composition or film, the presence or absence of clouding phenomenon and perspiration phenomenon of the plasticizer, transparency, tensile strength, elongation and tear strength were evaluated by the following methods.

(White turbidity phenomenon) The appearance of the obtained film was visually evaluated.

(Sweating phenomenon) The appearance of the obtained film was visually evaluated.

(Transparency) Using an integrating sphere type light transmittance measuring device, haze (cloudiness value) was evaluated according to JIS K 7105.

(Tensile Strength and Elongation) JIS Z 17
It measured based on 02.

(Tear strength) Measured in accordance with JIS P 8116.

The results obtained are shown in Table 1. The results of Example 2 and Comparative Examples 1 to 4 below are also shown in Table 1.

Example 2 A film having a thickness of 50 μm was prepared in the same manner as in Example 1 except that the amount of diisobutyl adipate added was changed to 40 parts by weight.
The same test was performed.

Comparative Example 1 A film having a thickness of 50 μm was prepared in the same manner as in Example 1 except that diisobutyl adipate was not added, and the same test as in Example 1 was conducted.

<Comparative Example 2> Polypropylene resin was used as low density polyethylene (Yukaron ZE41, MF manufactured by Mitsubishi Petrochemical Co., Ltd.).
A film having a thickness of 50 μm was produced in the same manner as in Example 1 except that the R was 0.5 and the density was 0.922 g / cm ³ ), and the same test was performed.

<Comparative Example 3> Polypropylene resin is a random copolymer polypropylene resin containing 6% of ethylene (Showaroma FD332 MFR5.
0, except that the density was 0.90 g / cm ³ )
A film having a thickness of 50 μm was produced in the same manner as in Example 1, and the same test as in Example 1 was performed.

<Comparative Example 4> Polypropylene resin was replaced with polypropylene resin (Showaroma FD33 manufactured by Showa Denko KK).
2) 100 parts by weight of an ethylene- [alpha] -olefin copolymer (Mitsui Petrochemical Co., Ltd. Tuffmer P-0280, MFR2.
9, a density of 0.87 g / cm ³ ) was changed to a blend of 20 parts by weight, and a film having a thickness of 50 μm was produced in the same manner as in Example 1, and the same test as in Example 1 was performed. .

[0051]

[Table 1]

According to Table 1, in the films obtained in Examples 1 and 2, no leaching phenomenon, white turbidity phenomenon and perspiration phenomenon were observed, and there was no significant change in physical properties, and the plasticizer was dissolved in the resin. It is clear that The films obtained in Comparative Examples 2 and 3 were not practical because they had a clouding phenomenon and a sweating phenomenon.

Example 3 20 parts by weight of diisobutyl adipate (D14A manufactured by Sanken Kako Co., Ltd.) as a plasticizer was added to 100 parts by weight of the polypropylene resin used in Example 1 and kneaded with a biaxial kneader, A pelletized mixture was obtained. This mixture was extruded into a sheet with a T die kept at 220 ° C. and cooled to 30 ° C. with a cooling roll. Thickness 16
This unstretched sheet of 0 μm was stretched 4 times in the machine direction by a roll stretching machine heated to 65 ° C. Then, this stretched film was annealed for 5 seconds through a 60 ° C. hot roll to prepare a film having a thickness of 43 μm.

The obtained film was labeled by the following method, and the resulting package was evaluated for adhesiveness in appearance, shrinkage back after cooling, boil characteristic and retort characteristic.

(Labeling method) The film is set to 117 mm in length (direction perpendicular to the stretching direction) and 223 mm in width (stretching direction).
After excision, the ends parallel to the longitudinal direction were made to overlap each other by impulse sealing so that the ends overlap each other by 5 mm to produce a cylindrical article. This cylindrical object is a bottle of a 300 ml glass bottle with a height of 140 mm, a body diameter of 68.5 mm, and a height of 117 mm from the bottom, the diameter of the shoulder is about 55 mm. The bottle is protected from the shoulder to the bottom. After mounting on 200 ℃
It was left in the oven for 10 seconds, and the stretched film was heat-shrinked to obtain a labeled glass bottle package.

(Appearance of appearance) The appearance of the obtained package was visually evaluated. The evaluation criteria are as follows. ○ ・ ・ ・ It was completely attached to the bottle. ×: The bottle did not completely adhere to the bottle and the shrinkage was insufficient.

(Reduction of shrinkage after cooling) After leaving the obtained package for 24 hours at room temperature, the appearance of the package was visually evaluated. The evaluation criteria are as follows. O: The film did not separate from the bottle shoulder even after being cooled after shrink-wrapping. ×: The film separated from the bottle at the bottle shoulder by cooling after shrink-wrapping.

(Boiled property) The obtained package was heated at 90 ° C.
After being immersed in hot water for 20 minutes, the appearance when taken out was evaluated. The evaluation criteria are as follows. ○: There was no change from before treatment. ×: Partial loosening or clouding occurred.

(Retort characteristics)
After steam treatment at 0 ° C. for 40 minutes, the appearance when taken out was evaluated. ○: There was no change from before treatment. ×: Partial loosening or clouding occurred.

The results obtained are shown in Table 2. The results of Example 4 and Comparative Examples 5 to 7 below are also shown in Table 2.

Example 4 A film was prepared in the same manner as in Example 3 except that the amount of the plasticizer added was 40 parts by weight, and the same test as in Example 3 was performed.

Comparative Example 5 A film was prepared in the same manner as in Example 3 except that no plasticizer was added and the draw ratio was set to 2. The same test as in Example 3 was performed.

Comparative Example 6 A film was prepared in the same manner as in Example 3 except that the plasticizing agent was not added and the stretching temperature was 90 ° C., and the same test as in Example 3 was conducted.

Comparative Example 7 A film was prepared in the same manner as in Example 3 except that the stretching temperature was 80 ° C., and the same test as in Example 3 was conducted.

[0065]

[Table 2]

According to Table 2, the heat-shrinkable films obtained in Examples 3 and 4 were sufficiently heat-shrinked even at a low stretching temperature of 65 ° C., and the appearance adhesion of the heat-shrinkable films obtained was It can be seen that the shrinkage return after cooling, the boil characteristics and the retort characteristics are excellent. The heat-shrinkable films obtained in Comparative Examples 5 to 7 are not suitable for practical use because they have insufficient heat shrinkage, appearance adhesion, shrinkage reversion after cooling, boil characteristics and retort characteristics.

[0067]

EFFECTS OF THE INVENTION According to the present invention, heat shrinkage that does not cause bleeding of plasticizer (leaching), sweating phenomenon (sweat), loss of transparency (devitrification), white turbidity, etc. according to the present invention A transparent film can be obtained. According to the present invention, a heat shrinkage of 20% or more can be achieved at around 80 ° C and at 85 ° C.
A heat-shrinkable film that can be sterilized as described above can be obtained. The heat-shrinkable film of the present invention has a small specific gravity, and when it is used as a shrink-wrapping material for a container, it can be easily separated and collected from the container and is safe without environmental problems.

Claims (3)

[Claims] 1. A weight average molecular weight of 80,000 to 50.
The polypropylene resin is in the range of 10,000, and the resin elution amount at 0 ° C or more and 20 ° C or less by the cross fractionation method is less than 5% by weight of the total polypropylene resin amount, and at 20 ° C or more and 70 ° C or less. The resin elution amount is 8 to 30% by weight of the total polypropylene resin amount, and is more than 70 11
Resin composition in which 5 to 60 parts by weight of a plasticizer is added to 100 parts by weight of a polypropylene resin having a composition in which the amount of resin eluted at 0 ° C. or less is 70 to 95% by weight of the total amount of polypropylene resin. A heat-shrinkable film molded from a material. 2. The plasticizer is tri-n-butyl citrate, diisodecyl phthalate, diisodecyl adipate,
The heat-shrinkable film according to claim 1, which is selected from the group consisting of dioctyl sebacate, trioctyl phosphate, -n-butyl oleate and diisobutyl adipate. 3. The heat-shrinkable film according to claim 1, which is stretched at least twice in at least one direction at a temperature of 80 ° C. or lower.