TWI447165B - Material for tube molding and thermal-shrinking film - Google Patents

Description

Tubular forming material and heat shrinkable film

The present invention relates to a material for tubular molding and a heat shrinkable film formed using the same.

In the heat-shrinkable film used for the shrink wrap or the like, vinyl chloride has been used in the past, but in recent years, a block copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene or a resin composition thereof has been used. There are several types of methods for producing the heat-shrinkable film, and the most convenient method is a method called a tubular method.

It is difficult to produce a heat-shrinkable film by a tubular method using the above-described block copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene or a resin composition thereof, and Patent Document 1 discloses that the stretching step is strictly performed. Temperature control for forming stability. Further, Patent Document 2 discloses that when a block copolymer composed of a certain vinyl aromatic hydrocarbon and a conjugated diene is used, the tubular method is suitable.

[Patent Document 1] JP-A-50-6673

[Patent Document 2] Japanese Patent Publication No. 07-216186

The tubular method extrudes the molten resin from a ring-shaped extrusion die, controls the tube to an appropriate temperature, and injects a gas into the tube to expand it (hereinafter referred to as "bubble formation"). A method of manufacturing a heat shrinkable film by extending in a direction perpendicular to the film. The tube is formed so that the necessary force for extending the film is obtained by injecting gas into the tube by the difference between the gas pressure in the tube and the gas pressure outside the tube.

In the tubular film forming method, since the film which is tubularly extruded from the die is folded by a pinch roll before being cooled to room temperature, there is a problem that adhesion occurs between the inner faces of the film. Therefore, it is difficult to peel off between the films again, so that a stable film cannot be produced, and when the film forming machine is folded in the form of a pinch roll at or near the softening temperature of the resin, There are situations where it is even more difficult to manufacture.

The tubular film forming method has a case where the expanded tube is brought into contact with the cooling ring to fix the width of the film, and the previous resin composition composed of the vinyl aromatic hydrocarbon and the conjugated diene is inferior in sliding property to the cooling ring. For other reasons, there may be cases where a stable film cannot be produced.

Therefore, in order to produce a stable film, a resin composition containing a block copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene is desired, and it is desired to develop a material for tubular molding which has both adhesive resistance and slidability.

The present invention provides a tubular molding material having a vinyl aromatic hydrocarbon and a conjugated diene as a main component and a heat shrinkable film using the molding material, which is excellent in bubble formation stability when a heat-shrinkable film is produced. purpose.

That is, the present invention has the following gist.

(1) A material for tubular molding comprising a block forming copolymer comprising a block copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene as a main component, and containing (I) a melting point according to JIS K2235 The average degree of polymerization of the glycerin skeleton of the microcrystalline wax of 75 ° C to 98 ° C and the glyceride of (II) is 1 to 10, and the carbon number of R of the fatty acid ester group represented by the formula R-COO- is 11 ~21 glyceride.

(2) The tubular molding material according to (1), which contains 0.01 to 3 parts by mass of the microcrystalline wax (I) and 0.01 to 3 parts by mass of the glyceride (II).

(3) A heat-shrinkable film obtained by using a material for tubular molding as in (1) or (2).

(4) A coating material for a PET bottle, which is obtained by using a heat shrinkable film of (3).

By using the tubular molding material of the present invention, the adhesion resistance and the slidability are improved, and when the film is produced by the tubular method, the adhesion between the films due to physical factors such as the pressure of the pinch rolls can be eliminated. .

Further, it is possible to reduce the frictional resistance caused by the contact between the equipment such as the cooling ring and the film, and to stably produce a heat-shrinkable film having a good appearance.

The material for tubular molding of the present invention is a block copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene as a main component, and it is necessary to contain (I) a microcrystalline wax and (II) a glyceride.

In the tubular method, most of the steps of folding the tubular film using a pinch roller are due to the physical pressing between the films, when the softening point of the tubular forming material used is low, or the film temperature is high. When the state is folded by the pinch roller, the film is melted to cause bonding, and there is a case where a favorable film cannot be stably produced.

The adhesion can be alleviated by increasing the glass transition temperature of the tubular molding material, but on the other hand, the elongation is deteriorated and the shrinkage at low temperatures is impaired. Therefore, in order to exhibit good adhesion prevention performance without increasing the glass transition temperature of the tubular molding material, it is necessary to add a filler or an additive having anti-blocking properties.

Examples of the filler having anti-blocking properties include cross-linked beads of high impact polystyrene (HIPS), vinyl aromatic hydrocarbon-(meth)acrylate and/or (meth)acrylic copolymer, and ethylene. Inorganic beads of crosslinked beads, ceria beads, quartz beads, etc. of the aromatic hydrocarbon copolymer.

When a film having a good transparency is required, a crosslinked bead of a HIPS, a vinyl aromatic hydrocarbon-(meth)acrylate and/or a (meth)acrylic copolymer, or a vinyl aromatic hydrocarbon copolymer is used. Lianzhu is preferred. The compounding ratio of the fillers is 10 parts by mass or less, preferably 0.05 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, per 100 parts by mass of the composition of the block copolymer.

Examples of the additive having anti-blocking properties include a slip agent, an antifogging agent, and an antistatic agent. In particular, a general agent is used as a lubricant. Examples of the slip agent include a fatty acid, a fatty acid ester, a fatty acid decylamine, a glycerin fatty acid ester (glyceride), a sorbitan fatty acid ester, a neopentyl glycol fatty acid ester, a sucrose fatty acid ester, and a propylene glycol fatty acid. Polyester wax, paraffin wax, microcrystalline wax, petrolatum, etc., such as esters and the like.

In the tubular method, after the resin melted by using the extrusion die is tubularly discharged, since it is folded by the pinch roller in a state of not being sufficiently completely cooled, it is necessary to immediately exhibit anti-adhesive properties after extrusion, and then The step of folding, because of the folding of the pinch rolls in the hot water tank set to the extension temperature, must exhibit anti-adhesive properties at a higher temperature.

In order to exhibit anti-adhesive properties at high temperatures, in addition to the filler having the aforementioned anti-blocking properties, higher melting hydrocarbon waxes such as polyethylene wax, polypropylene wax, microcrystalline wax, paraffin wax, petrolatum, etc. are used. good. It is more preferable to use polyethylene wax, polypropylene wax or microcrystalline wax, and microcrystalline wax is preferred.

The melting point of the microcrystalline wax is preferably 75 ° C to 98 ° C according to the method of JIS K 2235-5.3.2. When the melting point of the microcrystalline wax is less than 75 ° C, the microcrystalline wax tends to excessively migrate to the surface of the film, and in addition to the deterioration of the appearance of the film, there is a case where the printability to the film is deteriorated. On the other hand, when the melting point of the microcrystalline wax is higher than 98 ° C, the speed of migration to the surface of the film is insufficient, and there is a case where the immediate anti-adhesive property cannot be obtained. In order to ensure a sufficient transfer speed, although there is a method of increasing the temperature of the film, it may be difficult to form a stable tube.

Here, the specification of the above JIS K2235-5.3.2 corresponds to the ASTM D1321 specification.

The melting point of the microcrystalline wax of the present invention is measured by the following method. Device name: melting point tester (manufactured by MEITEC Co., Ltd., trade name: automatic wax melting point tester WMP-104 type) Test method: According to J IS K2235-5.3.2, the molten sample is adhered and solidified to the mercury ball of the melting point measurement thermometer. The part is heated under predetermined conditions, and the temperature at which the first drop falls from the thermometer is measured.

The amount of the microcrystalline wax added is 0.01 to 3 parts by mass, preferably 0.03 to 1 part by mass, more preferably 0.1 to 0.3 part by mass, per 100 parts by mass of the block copolymer. When the microcrystalline wax is less than 0.01 parts by mass, it may be difficult to exhibit anti-adhesive properties. On the other hand, when the microcrystalline wax is more than 3 parts by mass, there is a case where it is unstable when it is extruded by an extruder.

When a hydrocarbon wax having a high melting point is used as a monomer, the transition speed to the surface of the film is not sufficient, and the anti-bonding property excellent in immediate effect cannot be obtained. In order to achieve the anti-adhesive property at a high temperature, it is preferably used immediately after the molten resin is discharged, and it is preferably used in combination with a lubricant having a high mobility.

As the lubricant having high mobility, it is preferred to select a lubricant which is suitably low in solubility in the tubular molding material. A material for tubular molding having a block copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene as a main component, a lubricant having a relatively high hydrophilicity, for example, a glycerin fatty acid ester (glyceride), A fatty acid ester of a polyhydric alcohol such as a sorbitan fatty acid, a neopentyl glycol fatty acid ester or a sucrose fatty acid ester is preferred, and a glyceride is more preferred.

The amount of the glyceride to be added is 0.01 to 3 parts by mass, preferably 0.03 to 1 part by mass, more preferably 0.1 to 0.5 part by mass, per 100 parts by mass of the block copolymer. When the amount of the glycerin is less than 0.01 part by mass, the slidability with the sizing ring may not be sufficiently exhibited. On the other hand, when the glyceride is more than 3 parts by mass, there is a case where it is unstable during extrusion.

The glyceride is preferably a glyceride having a carbon number of R of 11 to 21 in the fatty acid ester group represented by the formula R-COO-, more preferably 17 to 21.

When the carbon number of R of the glyceride is less than 11, the decrease in the compatibility with the hydrocarbon-based wax causes a decrease in the rate of development of the anti-adhesive property from the hydrocarbon-based wax, and it is also difficult to impart appropriate solubility to the tubular molding material. When it is 23 or more, the hydrophilicity is lowered too much, and it may become difficult to exhibit sufficient slidability with a cooling ring.

Further, the average degree of polymerization of the glyceride-based glycerin skeleton is preferably from 1 to 10, more preferably from 1 to 4.

When the average degree of polymerization of the glycerin skeleton is more than 10, the hydrophilicity is increased too much, and it is difficult to impart appropriate solubility to a tubular molding material containing a block copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene as a main component. . The index indicating the hydrophilicity of the glyceride is usually an HLB value, and the preferred glyceride used for the tubular molding material of the present invention has an HLB value of from 3 to 16, more preferably from 4 to 12. When the HLB value of the glyceride is less than 3, the hydrophilicity is lowered too much, and the slidability with the cooling ring may not be sufficiently obtained. On the other hand, when the HLB value of the glyceride is more than 16, the compatibility with the tubular molding material is too much lowered, and it may be difficult to disperse it in the resin.

Examples of the vinyl aromatic hydrocarbon used for producing the block copolymer of the present invention include styrene, o-methyl styrene, p-methyl styrene, p-tert-butyl styrene, and 2,4-di. Methylstyrene, 2,5-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinyl anthracene, etc., of which styrene is preferred.

Examples of the conjugated diene used in the production of the block copolymer of the present invention include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), and 2,3. - dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, etc., of which 1,3-butadiene and isoprene are preferred.

The block copolymer used in the present invention can be a vinyl aromatic hydrocarbon and a conjugated diene by using an organolithium compound as an initiator in a dehydrated organic solvent and, if necessary, allowing a randomizer to coexist. The monomers are copolymerized to make. As the organic solvent, an aliphatic hydrocarbon such as butane, pentane, hexane, isopentane, heptane, octane or isooctane, or a fat such as cyclohexane, methylcyclohexane or ethylcyclohexane can be used. A cyclocarbon or an aromatic hydrocarbon such as benzene, toluene, ethylbenzene or xylene.

The organolithium compound is a compound in which one or more lithium atoms are bonded to each other in the molecule, and for example, a single such as ethyllithium, n-propyllithium, n-butyllithium, t-butyllithium or t-butyllithium can be used. In addition to the functional organolithium compound, a polyfunctional organolithium compound such as hexamethylenedilithium, butadienyldilithium or isoprenyldilithium may also be used.

As the randomizer, tetrahydrofuran (THF) is mainly used, and ethers, amines, thioethers, phosphoniumamines, alkylbenzenesulfonates, alkoxides of lithium and sodium, and the like can also be used.

Examples of the ethers include dimethyl ether, diethyl ether, diphenyl ether, diethylene glycol dimethyl ether, and diethylene glycol dibutyl ether. In addition to the tertiary amine, for example, trimethylamine, triethylamine or tetramethylethylenediamine, an internal cyclic amine or the like can be used. Further, triphenylphosphine, hexamethylphosphoniumamine, potassium alkylphenylsulfonate or sodium, potassium or sodium butoxide may be used as the randomizer.

The amount of the randomizer to be added is 10 parts by mass or less, preferably 0.001 to 8 parts by mass, per 100 parts by mass of the total monomer to be added. The addition period may be before the start of the polymerization reaction or during the polymerization. Also, it can be added as necessary.

The block copolymer solution thus obtained is inertized by adding a sufficient amount of a polymerization stopper such as carbon dioxide to inactivate the active terminal. As a method of recovering a block copolymer from the block copolymer solution, a method of depositing the solution by using a weak solvent such as methanol can be used, and a method of evaporating and evaporating the solvent using a heating roll (drum dryer method) A method in which a solution is concentrated by a concentrator, a solvent is removed by using a vented extruder, and a method of dispersing the solution in water and blowing water vapor to heat the solvent (vapor stripping method) is arbitrarily used.

The material for tubular molding of the present invention can be used alone or in combination with a plurality of block copolymers. Further, it is also possible to further copolymerize with different polymers such as a vinyl aromatic hydrocarbon polymer, a copolymer of a vinyl aromatic hydrocarbon polymer and a conjugated diene, and a copolymer of a vinyl aromatic hydrocarbon and a (meth) acrylate. The compound, the polyhydrocarbon or the like is used in combination, and the compounding ratio is preferably 30 parts by mass or less based on 100 parts by mass of the composition of the block copolymer. The mixing system mainly uses a method in which the extruder is mixed while being melted, and a method in which the solution of each component is blended, and the solvent is removed by the above method.

The additive is mainly a thermal stabilizer, a weather resistance enhancer, etc., in addition to the above-mentioned slip agent, antifogging agent, antistatic agent, and the like. As the thermal stabilizer, for example, 2-tert-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, 2-[1- (2-hydroxy-3,5-di-t-pentylphenyl)ethyl]-4,6-di-p-pentyl phenyl acrylate, n-octadecyl-3-(4-hydroxy-3, a phenolic antioxidant such as 5-di-tert-butylphenyl)propionate, or 2,2'-methylenebis(4,6-di-t-butylphenyl)octyl phosphite, ginseng ( A phosphorus-based antioxidant such as 2,4-di-tert-butylphenylphosphite.

Examples of the weather resistance improving agent include a benzotriazole-based ultraviolet absorber such as 2-(2-hydroxy-3-t-butyl-5-methylphenyl)-5-chlorobenzotriazole or A hindered amine type weathering enhancer such as bismuth (2,2,6,6-tetramethyl-4-piperidinyl)-1,2,3,4-butanetetracarboxylate. It is also possible to add white oil, eucalyptus oil, and the like.

These additives are preferably contained in the block copolymer composition in an amount of 5 parts by mass or less.

The heat-shrinkable film obtained by using the tubular molding material of the present invention is particularly preferably used for a heat-shrinkable label, a heat-shrinkable lid seal, or the like, and may be suitably used in a packaging film or the like.

The tubular molding material of the present invention and the heat-shrinkable film using the same are described above, but the present invention is not limited to the one embodiment of the present invention.

[Examples]

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to the examples.

[Reference Example 1]

(1) 490 kg of cyclohexane was added to the reaction vessel.

(2) 35.7 kg of styrene monomer was added, and 1600 ml of n-butyllithium (10 mass% cyclohexane solution) was added at an internal temperature of 30 ° C while stirring to polymerize.

(3) The internal temperature was lowered to 40 ° C, and 69.3 kg of styrene monomer and 8.9 kg of butadiene monomer were added in batches, and then fully polymerized.

(4) The internal temperature was set to 60 ° C, and 69.3 kg of styrene and 26.8 kg of butadiene were added in batches, and the polymerization was completed.

[Reference Example 2]

(1) 500 kg of cyclohexane was added to the reaction vessel.

(2) 8.0 kg of styrene monomer was added, and 1280 ml of n-butyllithium (10 mass% cyclohexane solution) was added at 30 ° C while stirring to polymerize.

(3) While maintaining the internal temperature at 80 ° C, a total of 110.0 kg of styrene monomer and a total of 13.4 kg of butadiene monomer are each 87.8 kg / h, 10.7 kg / h. The speed is added and both are added at the same time, and after the end of the addition, the state is maintained for a sufficient period of time.

(4) After the butadiene was completely consumed, the internal temperature was 75 ° C and 18.6 kg of butadiene monomer was added in batches, followed by polymerization.

(5) Further adding 50.0 kg of styrene monomer in batches and allowing it to complete polymerization.

[Reference Example 3]

(1) 500 kg of cyclohexane was added to the reaction vessel.

(2) 4.0 kg of a styrene monomer was added, and 1950 ml of n-butyllithium (10 mass% cyclohexane solution) was added at an internal temperature of 30 ° C while stirring to polymerize.

(3) While maintaining the internal temperature at 80 ° C, a total of 119.0 kg of styrene monomer and a total of 11.8 kg of butadiene monomer are each 100.8 kg / h, 10.0 kg / h. The speed is added and both are added at the same time, and after the addition is completed, the state is maintained for a sufficient period of time.

(4) After the butadiene was completely consumed, the internal temperature was 70 ° C and 36.4 kg of butadiene monomer was added in batches, followed by polymerization.

(5) Further adding 28.8 kg of styrene monomer in batches and allowing it to complete polymerization.

The characteristics of the block copolymers of Reference Examples 1 to 3 thus obtained are shown in Table 1. Further, in the table, A represents a polystyrene block, a B-based polybutadiene block, a C-based random block, and a D-based tapered block.

The block copolymers of Reference Examples 1 to 3 were mixed and mixed as Reference Compound 1 / Reference Example 2 / Reference Example 3 = 33.3 mass% / 33.3 mass% / 33.4 mass% as a mixed resin composition. Further, for each of the mixed resin compositions of 100 parts by mass, various slip agents were further added in the amounts shown in Tables 2 to 4. Further, the materials for tubular molding of Examples 1 to 11 and Comparative Examples 1 to 8 were obtained by melt-kneading at 200 ° C using a uniaxial extruder. Further, the melting point of the microcrystalline wax is measured in accordance with the method described in JIS K2235-5.3.2.

The tubular molding materials of the examples and the comparative examples shown in Tables 5 and 6 were used in a tubular film forming machine (manufactured by YI-CHEN Co., Ltd., model: MCE-50) which is a conventional water tank extension preheating method, and The film formation test was carried out by the following method, and the state thereof was observed, and the obtained heat shrinkable film was evaluated in accordance with the method described later. The results are shown in Tables 5 and 6.

(1) The materials for forming the tubular molding shown in Tables 5 and 6 were placed in an extruder, melt-kneaded at 200 ° C, and sufficiently plasticized, and then discharged in a tubular manner. Subsequently, a gas is injected into the pipe, and an arbitrary pipe diameter is formed by cooling the pipe from the outside of the pipe in a manner that the pipe is stably expanded.

(2) using a pinch roller located at an arbitrary height than the extrusion die, folding the tube, and adjusting the gap interval of the extrusion die, the number of screw revolutions, as necessary, in such a manner that the average thickness of the obtained film is about 0.1 mm. Clamping roller speed. Further, the pressing force of the pinch roller is adjusted to minimize the force required for the gas in the pipe of the first stage to leak to the pinch roller.

(3) The film folded using the pinch roller was taken, and the adhesion between the films was evaluated in accordance with the following criteria.

(A) Peel strength test between the inner faces of the tubes.

The pipe to be taken is based on the direction in which the pipe flows (hereinafter referred to as "MD direction") and the direction orthogonal to the pipe (hereinafter referred to as "TD direction"), and has a length of 15 mm in the MD direction and a length of 15 in the TD direction. Remove the millimeter and take it out to take the test piece. Draw a marking line at a position of 4 cm from the end of the test piece in the TD direction, set it as a boundary line and peel off the film on the shorter side, and peel the peeled film on the respective marking 90 The °C is bent to form a T-shaped test piece. This was carried out using a universal tensile tester (TENSILON) RTC-1210 manufactured by A&D Co., Ltd., and the ends of the respective films on the peeling side were fixed using a chuck, and the peel strength at the stretching speed of 200 mm/min was measured [ N]. The measured value was averaged from the measurement values of 15 seconds to 60 seconds after the start of stretching, and the same operation was repeated 10 times to calculate the average value Z[N].

(4) The film which has passed through the pinch roller is passed through a warm water tank of 85 ° C to carry out extension preheating, and injects gas so as to become an arbitrary pipe diameter to expand to a size sufficient to contact the pipe diameter direction. A cooling ring for fixing (hereinafter, this ring is referred to as a sizing ring) is formed to form a bubble (this operation is hereinafter referred to as sizing). Moreover, the bubble formation stability system was evaluated based on the following criteria.

(B) Gas injection

The "gas injection property" was a visual observation of the surface state between the inner surfaces of the tubes by the injection of gas, and was evaluated based on the following evaluation criteria. Good: Due to the injection of gas, the inner faces of the tubes are easily peeled off. Yes: Due to the injection of gas, although the inner surfaces of the tubes can be peeled off, they are resistant, and when the inner surfaces of the tubes are open, they emit sound or are accompanied by unstable vibrations. Poor: There is a bond between the inner faces of the tubes, causing film breakage or complete bonding during opening to allow gas injection.

(C) slidability with the sizing ring

"Slidability of the sizing ring" is a visual observation of the slidability of the film and the sizing ring when the gas is injected into the outside of the tube to sufficiently contact the sizing ring, and is evaluated according to the following evaluation criteria. Good: The slidability of the film and the sizing ring does not produce a sound from the dead pull and is stable. Yes: The slidability of the film and the sizing ring produces a sound from the dead pull and is slightly unstable. Poor: The pipe is hung on the sizing ring, and the pipe is significantly deformed or accompanied by cracking.

(5) The film after the formation of the bubble is taken to obtain a heat shrinkable film.

(D) Measurement of heat shrinkage rate.

The heat shrinkage ratio of the heat shrinkable film was measured by the following method.

(1) From the stretched film, a test piece having a length of 100 mm in the MD direction and a length of 100 mm in the TD direction was cut out.

(2) The test piece was immersed in warm water of 100 ° C for 10 seconds, taken out, and immediately water-cooled and wiped with water, and then the length L (mm) of MD and TD of the test piece was measured.

(3) The heat shrinkage rate was calculated from the following formula.

Heat shrinkage rate (%) = {(100.0-L)/100.0} × 100

From the results of Tables 5 and 6, it is found that the material for tubular molding of the present invention can be easily opened by laminating between the films even when the film is pressed between the films at a high temperature, and the film can be easily formed by the tubular film. The method can obtain a heat-shrinkable film in which bubbles are formed stably and heat shrinkability is excellent.

On the other hand, Comparative Examples 1 to 4 in which microcrystalline wax and glycerin other than the structure of the present invention were contained, and Comparative Examples 5 to 8 containing a different kind of slip agent were not able to sufficiently exhibit between the films. The anti-adhesion property and the slidability of the sizing ring cause the bubble formation to be unstable and cannot take a good film.

Further, if the content of the microcrystalline wax or the glycerin exceeds the predetermined range, the extrusion stability is remarkably lacking, and the smaller than the predetermined range is also because the anti-adhesive effect and the slidability of the sizing ring are hardly exhibited, and Unable to provide stable film formation.

[Industry use possibility]

As described above, the material for tubular molding of the present invention is suitable for a material for producing a heat-shrinkable film by a tubular method, and a film using the material can be suitably applied to a bottle label, a lid seal or the like. Further, the material for tubular molding of the present invention is also suitably used for various applications other than the tubular film forming method which are required to have high-temperature anti-blocking properties.

Claims (3)

A tubular molding material comprising a tubular molding material comprising a block copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene as a main component, and comprising: (I) a melting point of 75 in accordance with JIS K2235 The average degree of polymerization of the microcrystalline wax of °C~98°C and the glycerol skeleton of (II) glyceride is 1~10, and the carbon number of R in the fatty acid ester group represented by the general formula R-COO- is 11~ A glyceride of 21; which contains 0.01 to 3 parts by mass of the microcrystalline wax (I) and 0.01 to 3 parts by mass of the glyceride (II). A heat-shrinkable film obtained by using a material for tubular molding according to item 1 of the patent application. A coating material for a PET bottle, which is obtained by using a heat shrinkable film as in the second item of the patent application.